JP2007233032A - Focusing device and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focusing device and an imaging apparatus capable of achieving highly accurate focusing with high responsiveness. <P>SOLUTION: The focusing device is provided with: an imaging and focus detection means 212 picking up an image formed by an imaging optical system 202 and also detecting the focusing state of the imaging optical system 202 on the basis of image deviation of a pair of images formed by a pair of luminous fluxes passing through a pair of pupil areas of the imaging optical system 202; and a focus detection means 207 detecting the focusing state of the imaging optical system 202 or a range-finding means (240) detecting a distance to a subject, and performs the focusing of the imaging optical system on the basis of the result of detection by the imaging and focus detection means 212 and the focus detection means 207 or the range-finding means (240). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus that performs focus adjustment of an imaging optical system and an imaging apparatus that includes the focus adjustment apparatus.

  A phase difference detection type focus detection sensor and an image sensor are provided. Based on the detection result of the focus detection sensor, the imaging optical system is driven near the focus, and then the focus position is detected by the contrast detection method using the output of the image sensor. A digital camera that finely adjusts the in-focus position is known (for example, see Patent Document 1).

Prior art documents related to the invention of this application include the following.
JP 2001-281530 A

  However, in the above-described conventional camera, the contrast detection method and the phase difference detection method are different in compatibility because the principle of focus detection is different, and the matching of the results of focus detection by each method is poor. For example, a subject for which focus detection is possible with the phase difference detection method makes focus detection impossible with the contrast detection method, or a subject for which focus detection can be performed with high accuracy with the phase difference detection method, the focus detection accuracy deteriorates with the contrast detection method. Or Therefore, even if you try to fine-tune the contrast detection method after driving the lens in the vicinity of the focus once with the phase difference detection method, the imaging optical system will not hunt and converge to the focal point, or the imaging optical system will be placed at an outrageous position. The imaging optical system may not move at all.

(1) The invention of claim 1 is based on an image shift amount of a pair of images formed by a pair of light beams passing through a pair of pupil regions of the imaging optical system while capturing an image formed by the imaging optical system. And a focus detection unit for detecting the focus adjustment state of the imaging optical system and a focus detection unit for detecting the focus adjustment state of the imaging optical system, and based on the detection results of the imaging and focus detection unit and the focus detection unit. Adjust the focus of the imaging optical system.
(2) The focus adjusting apparatus according to claim 2 includes a light beam splitting unit that reflects the light beam from the subject that has passed through the imaging optical system to the imaging and focus detection unit and transmits the light beam to the focus detection unit.
(3) A focus adjusting apparatus according to a third aspect includes a light beam splitting unit that transmits a light beam from a subject that has passed through the imaging optical system to the imaging and focus detection unit and reflects the light beam to the focus detection unit.
(4) According to a fourth aspect of the present invention, the focus adjusting apparatus uses a half mirror that prevents back surface reflection as the light beam splitting means.
(5) The focus adjustment apparatus according to claim 5 is an optical path switching unit arranged to be inserted into and retracted from the optical path of the image pickup optical system, and picks up a light beam from a subject transmitted through the image pickup optical system in the retracted state. An optical path switching unit is provided that reflects the light beam from the subject that is guided to the double focus detection unit and transmitted through the imaging optical system in the inserted state to the focus detection unit.
(6) According to a sixth aspect of the present invention, the image pickup and focus detection means includes an image pickup device in which an image pickup pixel and a focus detection pixel are arranged on the same substrate.
(7) The focus detection pixel of the focus adjustment apparatus according to claim 7 includes a pair of photoelectric conversion units for one microlens.
(8) In the focus adjustment device according to the eighth aspect, the focus of the imaging optical system is based on the image shift amount of the pair of images formed by the pair of light beams passing through the pair of pupil regions of the imaging optical system by the focus detection unit. The adjustment state is detected.
(9) According to a ninth aspect of the present invention, the focus adjusting apparatus includes a pair of re-imaging optical systems that re-image the image formed on the planned focal plane of the imaging optical system and a pair of re-imaging optical systems. And an image sensor for detecting a pair of images re-imaged by.
(10) In the focus adjustment apparatus according to claim 10, the focus adjustment unit performs rough adjustment of the imaging optical system based on the detection result of the focus detection unit, and the imaging optical system based on the detection result of the imaging and focus detection unit. This is a fine adjustment.
(11) In the focus adjustment device according to the eleventh aspect, the focus adjustment unit performs focus adjustment of the imaging optical system based on the detection result of the focus detection unit until the shooting operation is started, and after the shooting operation is started. Is to adjust the focus of the imaging optical system based on the detection result of the imaging and focus detection means.
(12) The invention of claim 12 is based on an image shift amount of a pair of images formed by a pair of light beams passing through a pair of pupil regions of the imaging optical system while capturing an image formed by the imaging optical system. An imaging and focus detection means for detecting the focus adjustment state of the imaging optical system and a distance measurement means for detecting the distance to the subject are provided, and the imaging optical system is based on the detection results of the imaging and focus detection means and the distance measurement means. The focus is adjusted.
(13) In the focus adjustment device according to claim 13, the focus adjustment means performs rough adjustment of the imaging optical system based on the detection result of the distance measurement means, and also the imaging optical system based on the detection result of the imaging and focus detection means. This is a fine adjustment.
(14) In the focus adjustment device according to the fourteenth aspect, the focus adjustment unit performs focus adjustment of the imaging optical system based on the detection result of the distance measuring unit until the shooting operation is started, and after the shooting operation is started. Is to adjust the focus of the imaging optical system based on the detection result of the imaging and focus detection means.
(15) The invention of claim 15 is an imaging device including the focus adjustment device according to any one of claims 1 to 14.

  According to the present invention, since the imaging and focus detection unit having the imaging function and the focus detection function of the pupil division phase difference detection method is used, it is possible to realize focus adjustment with high responsiveness and high accuracy.

  A digital still camera will be described as an example of the focus detection apparatus of the present invention and an imaging apparatus equipped with the focus detection apparatus.

  FIG. 1 shows a configuration of a digital still camera according to an embodiment. The digital still camera 201 includes an interchangeable lens 202 and a camera body 203, and the interchangeable lens 202 is attached to the camera body 203 via a mount unit 204.

  The interchangeable lens 202 includes an objective lens 209, a zooming lens 208, a focusing lens 210, a diaphragm 211, and a lens drive control circuit 206. The lens drive control circuit 206 includes a CPU and a drive circuit (not shown), controls the driving of the focusing lens 210 and the aperture 211, detects the states of the zooming lens 208, the focusing lens 210 and the aperture 211, and communicates with a body CPU 214 described later. To transmit / receive lens information and focus adjustment information.

  On the other hand, the camera body 203 includes a half mirror 205, a focus detection sensor 207, an image sensor 212, a body CPU 214, an LCD driver 215, an LCD 216, an eyepiece lens 217, a memory card 219, a drive control circuit 220, an external operation member 221 and the like. .

  The half mirror 205 is disposed on the optical axis of the interchangeable lens 202 and separates the optical path into a reflection side and a transmission side. The half mirror 205 is formed with a reflection film for realizing a half mirror function on the surface of a glass plate having a predetermined thickness, and an antireflection film is formed on the back surface. The focus detection sensor 207 is disposed on the planned focal plane (scheduled imaging plane) of the interchangeable lens 202 on the transmission side of the half mirror 205 and has a focus detection function of the interchangeable lens 202. The focus detection sensor 207 incorporates a plurality of re-imaging type focus detection units (not shown) in order to perform focus detection at a plurality of focus detection positions.

  The imaging element 212 is disposed on the planned focal plane of the interchangeable lens 202 on the reflection side of the half mirror 205, and has a focus detection function and an imaging function of the interchangeable lens 220. Imaging pixels 212 are two-dimensionally arranged in the imaging element 212, and focus detection pixel arrays are incorporated in portions corresponding to a plurality of focus detection positions.

  In this specification, the focus adjustment of the focusing lens 210 based on the focus detection result by the focus detection sensor 207 is referred to as “dedicated AF” or “re-imaging type AF” as focus adjustment by the focus detection dedicated sensor. On the other hand, the focus adjustment of the focusing lens 210 based on the focus detection result by the focus detection pixel array of the image sensor 212 is referred to as “image sensor AF” or “microlens AF” as the focus adjustment by the image sensor.

  The body CPU 214 controls reading of outputs from the image sensor 212 and the focus detection sensor 207, communication with the lens drive control circuit 206 (transmission / reception of lens information / focus adjustment information), and the image sensor 212 during focus adjustment of the interchangeable lens 202. Switching control of the focus detection sensor 207, focus detection and focus adjustment adjustment control of the interchangeable lens 202, imaging control during imaging, operation control of the entire digital still camera, and the like are performed. The body CPU 214 and the lens drive control circuit 206 exchange various information such as lens information and a defocus amount for driving the focusing lens via an electrical contact part 213 provided in the mount part 204.

  The LCD 216 functions as a liquid crystal viewfinder (EVF: electronic viewfinder), and the LCD driver 215 drives the LCD 216 to display various information such as a captured image and imaging conditions. The photographer can visually recognize the information through the eyepiece 217. The memory card 219 is an image storage for storing and storing image signals. The drive control circuit 220 includes a camera control circuit such as a timer, and the external operation member 221 includes operation members used for various operations and settings of the digital camera such as a shutter button.

  The subject image that passes through the interchangeable lens 202 and is reflected by the half mirror 205 and formed on the image sensor 212 is photoelectrically converted by the image sensor 212, and its output is sent to the body CPU 214. On the other hand, the subject image that has passed through the interchangeable lens 202 and further passed through the half mirror 205 and formed on the focus detection sensor 207 is photoelectrically converted by an image sensor built in the focus detection sensor 207, and its output is the body CPU 214. Sent to.

  The body CPU 214 performs focus detection calculation based on the output of the focus detection pixel array of the image sensor 212 and the output of the focus detection sensor 207, and the focus adjustment state of the image formed on the image sensor 212 by the interchangeable lens 202, that is, defocusing. The amount is calculated, and this defocus amount is sent to the lens drive control circuit 206. The body CPU 214 stores the image signal generated based on the output of the imaging pixel in the memory card 219, and performs photometry of the object scene based on the output of the imaging pixel and the focus detection pixel to calculate the luminance. . Further, the body CPU 214 sends an image signal to the LCD driver 215 and causes the LCD 216 to display an image. Furthermore, the body CPU 214 switches and activates various controls in response to signals from the drive control circuit 220, and switches and activates various controls according to the switching of the external operation member 221 and the operation state.

  A CPU (not shown) of the lens drive control circuit 206 changes the lens information according to the focusing state, zooming state, aperture setting state, and the like. Specifically, the positions of the zooming lens 208 and the focusing lens 210 and the position of the stop 211 are monitored, and the lens information is calculated according to the monitor information, or according to the monitor information from a lookup table prepared in advance. Select the lens information. Further, the lens drive control circuit 206 calculates a lens drive amount based on the received defocus amount, and drives the focusing lens 210 to the in-focus point based on the lens drive amount.

  In the configuration of the embodiment shown in FIG. 1, since the image sensor 212 is disposed on the reflection side of the half mirror 205 and the focus detection sensor 207 is disposed on the transmission side, the following effects can be obtained. That is, since it is not necessary to retract the half mirror 205 each time an image is taken, the response in the image pickup is fast, and a photo opportunity can be reliably captured. In addition, there is no aberration deterioration of the captured image due to the transmission of the half mirror 205, and a high-quality image can be captured as compared with the transmission side. Furthermore, it is possible to perform focus adjustment with dedicated AF in parallel with imaging.

  FIG. 2 is a front view showing a detailed configuration of the image sensor 212. As shown in FIG. 2 (a), the imaging device 212 has imaging pixels 310 arranged in a two-dimensional array, and there are focal points at portions corresponding to the five focus detection positions shown in FIG. 11 (b) P11 to P15. The detection pixels 311 are arranged as shown in the figure. The imaging pixel 310 includes a microlens 10 and a photoelectric conversion unit 11 for imaging as shown in FIG. 2B, and the focus detection pixel 311 includes the microlens 10 and focus detection as shown in FIG. A pair of photoelectric conversion units 12 and 13 is provided.

  FIG. 3 is a cross-sectional view of the imaging pixel 310. In the imaging pixel 310, the microlens 10 is disposed in front of the imaging photoelectric conversion unit 11, and the photoelectric conversion unit 11 is projected forward by the microlens 10. The photoelectric conversion unit 11 is formed on the semiconductor circuit substrate 29.

  FIG. 4 is a cross-sectional view of the focus detection pixel 311. In the focus detection pixel 311, the microlens 10 is disposed in front of the focus detection photoelectric conversion units 12 and 13, and the photoelectric conversion units 12 and 13 are projected forward by the microlens 10. The photoelectric conversion units 12 and 13 are formed on the same semiconductor circuit substrate 29. The microlens 10 disposed in front of the imaging pixel 310 and the focus detection pixel 311 is disposed on the planned focal plane of the interchangeable lens 202.

  FIG. 5 is a diagram for explaining a pupil division type phase difference detection method using a microlens method. FIG. 5 shows some focus detection pixels 311 (microlenses 50 and 60 and two pairs of photoelectric conversion units 52, 53, 62, and 63). Reference numeral 90 denotes an exit pupil set at a distance d4 in front of the microlenses 50 and 60 disposed on the planned focal plane of the interchangeable lens 202. The distance d4 is a distance determined according to the curvature, refractive index of the microlens, the distance between the microlens and the photoelectric conversion unit, and the distance between the planned focal plane of the interchangeable lens 202 and the exit pupil. In this specification, it is called a distance measuring pupil distance.

  Reference numeral 91 denotes an optical axis of the interchangeable lens 202. Reference numeral 92 denotes a region (ranging pupil) of the photoelectric conversion units 52 and 62 projected by the microlenses 50 and 60, and 93 denotes a region (ranging pupil) of the photoelectric conversion units 53 and 63 projected by the microlenses 50 and 60. ). Two pairs of focus detection light beams 72, 73, 82, 83 from a subject that has passed through the pair of distance measuring pupil regions 93, 94 are paired with two pairs of photoelectric conversion units 52, 53, 62 via microlenses 50, 60. , 63 is reached.

  In FIG. 5, a focus detection pixel 311 (consisting of a microlens 50 and a pair of photoelectric conversion units 52 and 53) on the optical axis 91 and a focus detection pixel 311 (a pair of microlens 60 and a pair of photoelectric conversion units 52 and 53) are located outside the optical axis. The photoelectric conversion units 62 and 63) are schematically illustrated, but also in the other focus detection pixels 311, the focus detection light fluxes that arrive at the micro lenses from the pair of distance measurement pupils are also paired with the pair of photoelectric conversion units. Receive light respectively. The arrangement direction of the focus detection pixels 311 is made to coincide with the dividing direction of the pair of distance measuring pupils.

  The microlenses 50 and 60 are disposed in the vicinity of the planned focal plane of the optical system 202, and the shape of the pair of photoelectric conversion units 52 and 53 disposed behind the microlens 50 disposed on the optical axis 91 is the microlens. 50 and 60 are projected onto an exit pupil 90 separated by a projection distance d4, and the projection shape forms distance measuring pupils 92 and 93.

  On the other hand, the shape of the pair of photoelectric conversion units 62 and 63 disposed behind the microlens 60 disposed away from the optical axis 91 is projected onto the exit pupil 90 separated by the projection distance d4. Forms distance measuring pupils 92 and 93. That is, the projection direction of each pixel is determined so that the projection shape (ranging pupils 92 and 93) of the photoelectric conversion unit of each pixel matches on the exit pupil 90 at the distance measuring pupil distance d4.

  The photoelectric conversion unit 52 outputs a signal corresponding to the intensity of the image formed on the microlens 50 by the focus detection light beam 72 passing through the distance measuring pupil 92 and directed to the microlens 50. The photoelectric conversion unit 53 outputs a signal corresponding to the intensity of the image formed on the microlens 50 by the focus detection light beam 73 passing through the distance measuring pupil 93 and directed to the microlens 50.

  On the other hand, the photoelectric conversion unit 62 outputs a signal corresponding to the intensity of the image formed on the microlens 60 by the focus detection light beam 82 passing through the distance measuring pupil 92 and directed to the microlens 60. In addition, the photoelectric conversion unit 63 outputs a signal corresponding to the intensity of the image formed on the microlens 60 by the focus detection light beam 83 passing through the distance measuring pupil 93 and directed to the microlens 60.

  A large number of such focus detection pixels 311 are arranged in an array, and the outputs of the pair of photoelectric conversion units 12 and 13 arranged behind the focus detection pixels 311 are collected into an output group corresponding to the distance measurement pupil 92 and the distance measurement pupil 93. Information on the intensity distribution of a pair of images formed on the pixel array by the focus detection light beams passing through the distance measuring pupil 92 and the distance measuring pupil 93 is obtained. Then, by applying image shift detection calculation processing (correlation processing, phase difference detection processing) to be described later to these pieces of information, the amount of image shift between a pair of images by a so-called pupil division type phase difference detection method (microlens method). Can be detected.

  Further, the deviation (defocus amount) of the current imaging plane with respect to the planned focal plane can be calculated by multiplying the image shift amount by a predetermined conversion coefficient. Note that the defocus amount differs for each focus detection position. Further, the detection accuracy of the defocus amount (image shift amount) is determined by the detection pitch of the image shift amount, and in the case of the microlens method, the arrangement pitch of the microlenses.

  FIG. 6 is a front view showing the relationship between the projection areas (ranging pupils) of the pair of photoelectric conversion units 12 and 13 of the focus detection pixel 311 on the exit pupil plane 90. A circumscribed circle 94 of distance measuring pupils 92 and 93 (solid line) obtained by projecting the pair of photoelectric conversion units 12 and 13 of the focus detection pixel 311 onto the exit pupil plane 90 by the microlens 10 is predetermined when viewed from the planned focal plane. Of the aperture F value. In this specification, this aperture F value is referred to as a distance measuring pupil F value. Generally, when the open F value of the aperture opening of the interchangeable lens 202 is brighter than the distance measuring pupil F value, the focus detection light beam is not shielded by the aperture opening of the interchangeable lens 202, so that highly accurate focus detection is possible. become.

  When the distance of the exit pupil corresponding to the aperture opening of the interchangeable lens 202 does not match the distance measuring pupil distance, the open F value of the aperture opening of the interchangeable lens 202 is measured when focus detection is performed at a position around the screen. Even if it is brighter than the distance pupil F value, the focus detection light beam may be partially blocked at the pixels around the screen, and the focus detection accuracy deteriorates. In FIG. 6, points 95 and 96 are barycentric positions in the direction in which the distance measuring pupils 92 and 93 are arranged (x direction), and the size of the opening angle that sandwiches the barycentric positions 95 and 96 from the focus detection position on the planned focal plane. Accordingly, the value of the conversion coefficient used for converting the image shift amount into the defocus amount is determined. The focus detection accuracy increases as the opening angle increases, and the detection range of the defocus amount increases as the opening angle decreases.

  6 shows the distance measurement pupils corresponding to the focus detection positions P11, P12, and P13 in FIG. 11B, the distance measurement pupils corresponding to the focus detection positions P14 and P15 rotate FIG. 6 by 90 degrees. The circumscribed circle (ranging pupil F value) of the distance measuring pupil does not change.

  FIG. 7 shows a circuit configuration of the image sensor 212. The image sensor 212 includes a reading circuit for reading an output signal from the photoelectric conversion unit. 26 is a photoelectric conversion unit (corresponding to 11 in FIGS. 2 and 3) of the imaging pixel 310, and 27 and 28 are a pair of photoelectric conversion units (12 and 13 in FIGS. 2 and 4) of the focus detection pixel 311. Equivalent). The vertical transfer register 20 turns on and off the transfer MOS switch 24 installed corresponding to each of the photoelectric conversion units 26, 27, and 28, and outputs the outputs of the photoelectric conversion units 26 to 28 to the transfer MOS switch 25 for each pixel in one row. Forward.

  The horizontal transfer register 21 sequentially turns on and off the transfer MOS switch 25 and sequentially transfers the output transferred from the transfer MOS switch 24 to the amplification amplifier 23. The amplification amplifier 23 amplifies the output transferred from the transfer MOS switch and outputs the amplified output to the outside of the image sensor 212. These photoelectric conversion units, transfer MOS switches, registers, and amplifiers are formed on the semiconductor substrate 29.

  By configuring the image sensor 212 as a MOS image sensor instead of a CCD image sensor, the manufacturing cost can be reduced. Since the focus detection pixel is also configured as a MOS image sensor, only the focus detection pixel corresponding to the selected focus detection position can be read at high speed.

  FIG. 8 shows a detailed configuration of the focus detection sensor 207 corresponding to FIG. A focus detection method based on the re-imaging method will be described with reference to FIG. In the figure, 91 is the optical axis of the interchangeable lens 202, 110 and 120 are condenser lenses, 111 and 121 are aperture masks, 112, 113, 122 and 123 are aperture openings, 114, 115, 124 and 125 are re-imaging lenses, Reference numerals 116 and 126 denote image sensors (CCD) for focus detection, and 132, 133, 142, and 143 denote focus detection light beams.

  Reference numeral 101 denotes an exit pupil set to a distance d5 in front of the planned focal plane of the interchangeable lens 202. The distance d5 is a distance determined according to the focal lengths of the condenser lenses 110 and 120, the distances between the condenser lenses 110 and 120 and the aperture openings 112, 113, 122, and 123, and is called a distance measuring pupil distance. Reference numeral 102 denotes an area of the aperture openings 112 and 122 projected by the condenser lenses 110 and 120 (range-finding pupil), and reference numeral 103 denotes an area of the aperture openings 113 and 123 projected by the condenser lenses 110 and 120 (range-finding pupil). The condenser lens 110, the diaphragm mask 111, the diaphragm apertures 112 and 113, the re-imaging lenses 114 and 115, and the image sensor 116 constitute a focus detection unit for re-imaging pupil division phase difference detection in which focus detection is performed at one position. To do.

  FIG. 8 schematically illustrates a focus detection unit on the optical axis 91 and a focus detection unit outside the optical axis 91. By combining a plurality of focus detection units, as shown in FIG. 11A, a dedicated AF that performs focus detection by re-imaging pupil division method phase difference detection at five focus detection positions P1 to P5 as shown in FIG. Can do. The focus detection unit on the optical axis 91 is arranged to be arranged between the condenser lens 110 disposed in the vicinity of the planned focal plane of the interchangeable lens 202, the image sensor 116 disposed behind the condenser lens 110, and the condenser lens 110 and the image sensor 116. A pair of re-imaging lenses 114 and 115 for re-imaging the primary image formed in the vicinity of the focal plane on the image sensor 116, and a pair of re-imaging lenses disposed in the vicinity (front surface in the figure). A diaphragm mask 11 having diaphragm openings 112 and 113 is provided.

  The image sensor 116 is a line sensor in which a plurality of photoelectric conversion units are densely arranged along a straight line, and the arrangement direction of the photoelectric conversion units matches the dividing direction of the pair of distance measuring pupils (= the direction in which the aperture openings are arranged). Let Information corresponding to the light intensity distribution of the pair of images re-imaged on the image sensor 116 is output from the image sensor 116, and image shift detection calculation processing (correlation processing, phase difference detection processing) to be described later is performed on this information. By performing the above, it is possible to detect the image shift amount of a pair of images by a so-called pupil division type phase difference detection method (re-imaging method). Then, the deviation (defocus amount) of the current imaging plane with respect to the planned focal plane can be calculated by multiplying the image shift amount by a predetermined conversion coefficient.

  The image sensor 116 is projected onto the planned focal plane by the re-imaging lenses 114 and 115, and the detection accuracy of the defocus amount (image shift amount) is the detection pitch of the image shift amount (scheduled in the case of the re-image formation method). This is determined by the arrangement pitch of the photoelectric conversion units projected on the focal plane. The condenser lens 110 projects the aperture openings 112 and 113 of the aperture mask 111 onto the exit pupil 101 as regions 102 and 103. These areas 102 and 103 are called distance measuring pupils. That is, a pair of images re-imaged on the image sensor 116 is formed by a light beam passing through the pair of distance measuring pupils 102 and 103 on the exit pupil 101. The light beams 132 and 133 that pass through the pair of distance measurement pupils 102 and 103 on the exit pupil 101 are referred to as focus detection light beams.

  FIG. 9 is a diagram showing a distance measuring pupil on the exit pupil plane in the re-imaging method. A circumscribed circle 84 of the distance measurement pupils 102 and 103 (solid line) obtained by projecting a pair of aperture openings onto the exit pupil plane 101 by the condenser lens is a predetermined aperture F value (range measurement pupil F value) when viewed from the planned focal plane. It becomes. The range-finding pupil F value of the re-imaging method is set to be darker (larger as the F value) than the range-finding pupil F value of the microlens method shown in FIG.

  Points 85 and 86 are barycentric positions in the direction in which the distance measuring pupils 102 and 103 are arranged (x direction), and image shift is performed according to the size of the opening angle that sandwiches the barycentric positions 85 and 86 from the focus detection position of the planned focal plane. The value of the conversion coefficient used to convert the amount into a defocus amount is determined. The opening angle of the re-imaging method is set smaller than the opening angle of the microlens method shown in FIG. 6 so that a large defocus amount can be detected. 9 shows the distance measuring pupils corresponding to the focus detection positions P1, P2, and P3 in FIG. 11A, the distance measurement pupils corresponding to the focus detection positions P4 and P5 rotate FIG. 9 by 90 degrees. The circumscribed circle (ranging pupil F value) of the distance measuring pupil does not change.

  FIG. 10 shows a circuit configuration of an image sensor (CCD) of the focus detection sensor 207 used in the dedicated AF. 30 and 31 are an array of a pair of photoelectric conversion units corresponding to one focus detection position, 32 is a CCD transfer register for transferring an output from the pair of photoelectric conversion units 30 and 31, and 33 is a transfer from the CCD transfer register 32 This is an amplifier that amplifies the output and outputs it to the outside. In the CCD image sensor 117, five sets each including an array of a pair of photoelectric conversion units, a CCD transfer register, and an amplification amplifier are formed corresponding to the five focus detection positions in FIG.

  The charge accumulation time control, output transfer, and amplification of each set of photoelectric conversion units can be controlled completely independently. Since the operation control of the photoelectric conversion unit corresponding to a plurality of focus detection positions can be performed independently, even when the brightness of the plurality of focus detection positions is significantly different, by performing charge accumulation time control according to the brightness independently, An appropriate level of output can be obtained, which is suitable for the operation of performing focus detection at all focus detection positions simultaneously.

  FIG. 11 shows the focus detection position in the imaging screen 100 set on the planned focal plane of the interchangeable lens 202. FIG. 11A shows a region (focus detection area) in which an image is sampled in the imaging screen 100 when the focus detection sensor 207 for pupil division type phase difference detection of the re-imaging method performs focus detection. In the re-imaging method, an array of photoelectric conversion units of the image sensor is projected on the screen 100, and the projection area becomes a focus detection area. Accordingly, the length and width of the focus detection area and the sampling pitch are determined by the size of the photoelectric conversion unit, the arrangement length, the arrangement pitch, and the projection magnification of the re-imaging lens.

  FIG. 11B shows an area (focus detection area) where an image is sampled on the imaging screen 100 when focus detection is performed using the microlens method. In the microlens method, the arrangement of microlenses on the screen 100 serves as a focus detection area, and the length and width of the focus detection area and the sampling pitch are determined by the size, arrangement length, and arrangement pitch of the microlenses.

  FIG. 11C shows the focus detection areas of the re-imaging method (dedicated AF) and the microlens method (imaging element AF) superimposed. The five focus detection areas overlap each other. By setting the length of the focus detection area of the re-imaging method to be longer than the length of the focus detection area of the microlens method, it is possible to increase the shift amount in the image shift calculation, and the defocus amount detection range Can be widened. In the case of the microlens method, when the focus detection area is lengthened, it is necessary to increase the number of focus detection pixels, and the image quality at the time of imaging is deteriorated.

  Also, by making the width of the focus detection area of the re-imaging method (dedicated AF) wider than that of the focus detection area of the microlens method (image sensor AF), the output is reduced at low luminance and the charge accumulation time is increased. It is possible to prevent a decrease in response due to. In the case of the microlens method, if the width of the focus detection area is widened, it is necessary to increase the number of focus detection pixels or increase the focus detection pixel size, which degrades the image quality at the time of imaging.

  By making the detection pitch of the focus detection area of the re-imaging method (dedicated AF) finer than the detection pitch of the focus detection area of the microlens method (imaging device AF), the detection accuracy (focus detection accuracy) of the image shift amount is improved. Can be improved. Conversely, by reducing the detection pitch of the focus detection area, it is possible to prevent a decrease in output due to low brightness and a decrease in response due to an increase in charge accumulation time, while reducing the number of outputs and reducing the image shift calculation time. By shortening, it is possible to prevent a decrease in response. In the case of the microlens method (imaging device AF), it is more advantageous to align the pitch of the focus detection pixels with the arrangement pitch of the imaging pixels, and it is difficult to reduce the pitch of the focus detection pixels.

Table 1 summarizes the characteristics of AF (dedicated AF) using the refocusing focus detection sensor 207 and AF (imaging device AF) using the microlens method.

  In the size of the AF unit, the dedicated AF requires a space for re-imaging, and therefore is larger than the image pickup element AF, and particularly requires a thickness in the optical axis direction. On the other hand, the image pickup element AF is smaller than the dedicated AF because the photoelectric conversion unit is arranged immediately after the microlens, and can particularly reduce the thickness in the optical axis direction. In the focus detection luminance range, the dedicated AF can set the size of the photoelectric conversion unit to be large, so that it can cope with low luminance to high luminance. On the other hand, since the image sensor AF cannot be increased in size because it is embedded in the image sensor, it is difficult to cope with low luminance.

  In the defocus amount detection range, the dedicated AF has a long focus detection area length and a small opening angle of the center of gravity of the distance measuring pupil, so that a large defocus amount can be detected and the defocus amount detection range is wide. On the other hand, the image sensor AF has a short focus detection area length and a large opening angle of the center of gravity of the distance measuring pupil, so that the defocus amount detection range is narrow. In focus detection accuracy (defocus amount detection accuracy), the dedicated AF cannot be as accurate as the image sensor AF because the detection pitch on the planned focal plane is rough and the opening angle of the center of gravity of the distance measurement pupil is small. On the other hand, the image sensor AF is highly accurate because the detection pitch on the planned focal plane is fine and the opening angle of the center of gravity of the distance measuring pupil is large.

  In multi-AF area control (independent control of charge accumulation time and independent readout of output of a group of photoelectric conversion units corresponding to a plurality of focus detection positions), the dedicated AF is a group of photoelectric conversion units corresponding to each focus detection position. Since the CCD register for reading out the output is provided independently, independent control of the charge accumulation time and independent reading of the output are easy. On the other hand, the image sensor AF is provided with a group of photoelectric conversion units corresponding to each focus detection position and a readout circuit as a part of the image sensor, so that independent control of the charge accumulation time and independent readout of the output are difficult. .

  In a high-density arrangement of AF areas, the dedicated AF has to be provided with a re-imaging optical system corresponding to each focus detection position, so it is difficult to provide a large number of focus detection positions close to each other. On the other hand, it is easy for the image sensor AF to set an AF area corresponding to a close focus detection position only by arranging focus detection pixels on the image sensor surface.

  In the detection pitch, the dedicated AF increases the size of the photoelectric conversion unit in order to enable focus detection with low luminance, and thus the detection pitch cannot be made as fine as that of the image sensor AF. On the other hand, the imaging element AF can set the focus detection pixel to the same size as the imaging pixel, so that the detection pitch can be made fine.

  In pinpoint detection (focus detection in an extremely small image portion, for example, a human eye portion), the dedicated AF has a large photoelectric conversion unit size and the number of photoelectric conversion units sufficient to detect image misalignment. If secured, an area having a certain size is required, so it is not suitable for pinpoint detection. On the other hand, the image sensor AF is suitable for pinpoint detection because the size of the focus detection pixel is small, and the area can be reduced even if the number of photoelectric conversion units sufficient to detect image shift is secured.

  In conjunction with imaging, the dedicated AF is configured separately from the imaging device, so that relative placement error offset adjustment (mechanical or software) is used to calculate the defocus amount on the imaging device. is required. On the other hand, the image sensor AF does not require offset adjustment because the focus detection pixels are provided on the image sensor.

  In response to movement of the subject, the dedicated AF can perform focus detection independently in a plurality of AF areas at the same time, so it is reliable even for a subject that moves within the imaging screen 100 over time. The focus can be detected. On the other hand, the image sensor AF is not suitable for a moving subject because it is difficult to simultaneously detect the focus of a plurality of AF areas as compared with the dedicated AF.

  FIG. 12 is a flowchart showing the operation of the digital still camera (imaging device) shown in FIG. The body CPU 214 repeatedly executes this operation when the camera is turned on. When the camera is turned on in step 100, the imaging operation is started, and the process proceeds to step 110. In step 110, a focus detection operation is performed in all AF areas of the dedicated AF, and data is read out. In the next step 120, image shift detection calculation processing is performed based on a pair of image data corresponding to each AF area, and the image shift amount is calculated.

  FIG. 13 is a flowchart showing an image shift amount detection operation. In step 300, an image shift amount detection operation is started, and a correlation shift operation is performed on the pair of data within the shift range determined in step 310. In step 320, it is checked whether there is a minimum point to which the three-point interpolation calculation can be applied. If there is no minimum point, it is determined in step 360 that image shift cannot be detected (focus cannot be detected), and the process returns from step 370.

  On the other hand, if there is a minimum point in step 320, the process proceeds to step 330, and the maximum correlation amount is interpolated in the vicinity of the correlation amount having the highest correlation. In step 340, the reliability of the maximum correlation amount is determined. If there is no reliability, it is determined in step 360 that image shift cannot be detected (focus detection is impossible), and the process returns from step 370. If it is determined in step 340 that there is reliability, the process proceeds to step 350, and the process returns from step 370 with the shift amount giving the maximum correlation amount as the image shift amount.

  In step 130 of FIG. 12, the image shift amount corresponding to each AF area is converted into a defocus amount. FIG. 14 is a flowchart showing an operation for converting the image shift amount into the defocus amount. In step 400, the operation of defocus amount conversion is started and the process proceeds to step 410, where it is checked whether the image shift amount is undetectable.

  If it is determined in step 410 that the image shift amount can be detected, the process proceeds to step 420, where the defocus amount is obtained by multiplying the image shift amount by a predetermined conversion coefficient (differing between the re-imaging method and the micro lens method). Is calculated. In step 430, it is determined whether or not the image shift amount is calculated by the dedicated AF. If the image sensor AF is not the dedicated AF, the process returns from step 450. On the other hand, if it is calculated by the dedicated AF, the process proceeds to step 440, the offset amount is added to the calculated defocus amount, and the process returns from step 450.

  Here, the offset amount is the difference between the dedicated AF and the image sensor AF, and is detected by using an offset amount measured and stored in advance or by performing focus detection with the image sensor AF after focusing with the dedicated AF. The defocus amount thus set is used as an offset amount, and is fed back as an offset amount in the subsequent dedicated AF.

  Returning to FIG. 2 again, the explanation will be continued. In step 140, it is determined in which AF area the subject is captured based on the defocus amount of each AF area. For example, since the subject generally has a high probability of becoming the closest object in the imaging screen 100, the AF area in which the defocus amount indicating the closest side is calculated is recognized as the subject capturing area.

Here, an image shift detection calculation process (correlation algorithm) will be described by taking a certain AF area as an example. Assuming that a pair of data corresponding to a certain AF area is ei, fi (where i = 1 to m), first, a correlation amount C (L) is obtained by a differential correlation algorithm expressed by equation (1).
C (L) = Σ | e (i + L) −f (i) | (1)
In the formula (1), L is an integer and is a relative shift amount in units of a pitch of a pair of data. Further, the range of L is Lmin to Lmax (-5 to +5 in the figure). Further, the range of the parameter i is from p to q, and is determined so as to satisfy the condition of 1 ≦ p <q ≦ m. Furthermore, the size of the focus detection area is set by the values of p and q.

As shown in FIG. 16A, the calculation result of the expression (1) indicates that the correlation amount C (L) is high when the shift amount L = kj (kj = 2 in FIG. 16A) with a high correlation between a pair of data. Be minimized. Next, the shift amount x that gives the minimum value C (L) min = C (x) with respect to the continuous correlation amount is obtained by using the three-point interpolation method according to the equations (2) to (5).
x = kj + D / SLOP (2),
C (x) = C (kj) − | D | (3),
D = {C (kj-1) -C (kj + 1)} / 2 (4),
SLOP = MAX {C (kj + 1) -C (kj), C (kj-1) -C (kj)} (5)
Further, the defocus amount DEF with respect to the planned focal plane of the subject image plane can be obtained based on the calculated shift amount x by the equation (6).
DEF = KX · PY · x (6)
In Equation (6), PY is a detection pitch, and KX is a conversion coefficient determined by the size of the opening angle of the center of gravity of the pair of distance measuring pupils.

  Whether the calculated defocus amount DEF is reliable is determined as follows. As shown in FIG. 16B, when the degree of correlation between a pair of data is low, the value of the interpolated minimum amount C (X) of the correlation amount increases. Therefore, when C (X) is equal to or greater than a predetermined value, it is determined that the reliability is low. Alternatively, in order to normalize C (X) with the contrast of data, it is determined that the reliability is low when the value obtained by grading C (X) with SLOP that is proportional to the contrast is equal to or greater than a predetermined value. Alternatively, if SLOP that is proportional to the contrast is equal to or less than a predetermined value, it is determined that the subject has low contrast and the reliability of the calculated defocus amount DEF is low.

  As shown in FIG. 16C, when the correlation between the pair of data is low and there is no drop in the correlation amount C (L) between the shift ranges Lmin to Lmax, the minimum value C (X) is obtained. In such a case, it is determined that the focus cannot be detected.

  FIG. 15 is a flowchart showing the subject capture AF area recognition operation in step 140 of FIG. In step 500, the subject capture AF area recognition operation is started. In step 510, it is checked whether focus detection is impossible in all AF areas. If the focus cannot be detected, it is checked whether the image shift amount is undetectable. If not, in step 530, the central AF area (the central AF area of the imaging screen 100) is conveniently identified as the subject capturing AF area. Return from 540.

  On the other hand, if focus detection is possible in step 510, the process proceeds to step 520. If it is determined that there is at least one AF area, the AF area in which the defocus amount indicating the closest distance is calculated is recognized as the subject capture AF area. Then, the process returns from step 540.

  Returning to FIG. 12, it is checked in step 150 whether the absolute value of the defocus amount in the subject capturing AF area is within a predetermined value. The predetermined value is a value determined in advance for determining whether or not the focus is close to the dedicated AF. If the predetermined value is within the predetermined value, the focus is considered to be close to the focus. If focus detection is not possible (image shift detection is impossible) in all AF areas, the process proceeds to step 170. If it is determined that the lens is not in focus, the process proceeds to step 160, the defocus amount is transmitted to the lens drive control circuit 206, the focusing lens 210 of the interchangeable lens 202 is driven to the focus position, and the process returns to step 110 to return to the above. Repeat the operation.

  On the other hand, if it is determined that it is in the vicinity of the in-focus state, the process proceeds to step 170 to determine whether or not the shutter release has been performed. If it is determined that the shutter release has not been performed, the process returns to step 110 and the above operation is repeated. If it is determined that the shutter release has been performed, the process proceeds to step 180, and data is read from the focus detection pixels of the image sensor AF corresponding to the certified subject capturing AF area. In the next step 190, an image shift detection calculation process is performed based on a pair of image data corresponding to the subject capture AF area, and an image shift amount is calculated.

  In step 200, the image shift amount corresponding to the subject capture AF area is converted into a defocus amount. In the following step 210, it is checked whether the absolute value of the defocus amount in the subject capturing AF area is within a predetermined value. The predetermined value is a value determined to determine whether or not the image sensor AF is in focus (a value smaller than the predetermined value for determining whether or not the focus is in the vicinity of the dedicated AF). If it is within the predetermined value, it is considered that the subject is in focus and the process proceeds to step 230. If focus detection is not possible (image shift detection is impossible) in all subject capture AF areas, the process proceeds to step 230.

  If it is determined that it is not in focus, the process proceeds to step 220, the defocus amount is transmitted to the lens drive control circuit 206, the focusing lens 210 of the interchangeable lens 202 is driven to the focus position, and the process proceeds to step 230. In step 230, the image signal is read from the image pickup pixel of the image sensor, and in the subsequent step 240, the image signal is stored in the memory card 219, and the process returns to step 110 to repeat the above operation.

Table 2 shows a comparison example of the arrangement of the focus detection sensor (dedicated AF) using the re-imaging method in the digital camera and the image sensor (image sensor AF) using the microlens method.

  Arrangement example (1) is the arrangement shown in FIG. 1, in which a fixed half mirror is arranged in the optical path of the imaging optical system, imaging element AF is arranged on the reflection side, and dedicated AF is arranged on the transmission side. The feature of this arrangement example is that the half mirror is fixed and it is not necessary to retract the half mirror at the time of imaging, so imaging with a small release time lag can be performed. Further, since the image pickup device picks up an image with the reflected light of the half mirror, there is no image deterioration due to transmission through the glass constituting the half mirror. Furthermore, the focus adjustment can be performed by operating the dedicated AF in parallel with the imaging operation of the imaging device.

  Arrangement example (2) is an arrangement example shown in FIG. 18, in which a fixed half mirror is arranged in the optical path of the imaging optical system, and in contrast to arrangement example (1), a dedicated AF is arranged on the reflection side, and the transmission side is arranged. The image pickup element AF is arranged in FIG. In FIG. 18, the same components as those shown in FIG. The feature of this arrangement example is that the half mirror is fixed and it is not necessary to retract the half mirror at the time of imaging, so imaging with a small release time lag can be performed. In addition, since the imaging element is arranged in the optical axis direction, the thickness of the camera body 203 in the optical axis direction can be reduced, and a compact camera body 203 can be provided. Furthermore, the focus adjustment can be performed by operating the dedicated AF in parallel with the imaging operation of the imaging device.

  Arrangement example (3) is the arrangement example shown in FIG. 19, in which main mirror 230 (movable half mirror) is arranged in the optical path of the imaging optical system, and pentaprism 232 and eyepiece lens 217 arranged in the reflection-side optical path. The reflected light is guided to the optical viewfinder configured by the following. In FIG. 19, the same components as those shown in FIG.

  The light beam transmitted through the main mirror 230 is reflected by a sub-mirror 231 (movable total reflection mirror) disposed behind, guided to a focus detection dedicated sensor 207 disposed outside the imaging optical path, and focus detection is performed by the focus detection dedicated sensor 207. Is done. When there is an imaging instruction, the main mirror 230 and the sub mirror 231 are withdrawn from the imaging optical path, the imaging element receives the light beam, and focus detection and imaging are performed by the imaging element. The feature of this arrangement example is that the mirror retracts from the imaging optical path during imaging, and the imaging element directly receives the imaging light beam, so that a high-quality image can be obtained. Further, since the luminous flux is not divided into the dedicated AF and the image sensor AF, it is advantageous for securing the light quantity at the time of low luminance.

  Arrangement example (4) is the arrangement example shown in FIG. 20, such as external light rangefinder 240 (reflected light receiving active AF, image shift detection passive AF, TIME OF LIGHT type active AF using ultrasonic waves or light waves, etc. ) Is used as a dedicated AF. In FIG. 20, the same components as those shown in FIG. The image sensor AF 212 always receives the light beam from the interchangeable lens 202.

  Prior to the release, focus adjustment is performed using dedicated AF, and after release, the focus is adjusted using the image sensor AF, and then imaging is performed, so that focus detection can be performed even at low brightness, during large defocusing, and during multi-AF area operation. In addition, high-precision focusing can be achieved during imaging. The feature of this arrangement example is that it is not necessary to retract the half mirror at the time of imaging, and imaging with a small release time lag can be performed. In addition, there is no extra optical element in the imaging optical path during imaging, and the imaging element directly receives the imaging light beam, so that a high quality image can be obtained. Furthermore, since the luminous flux is not divided into the dedicated AF and the image sensor AF, it is advantageous for securing the light quantity at low luminance. Furthermore, the focus adjustment can be performed by operating the dedicated AF in parallel with the imaging operation by the imaging device.

専用ＡＦ（再結像方式）と撮像素子ＡＦ（マイクロレンズ方式）の使用状況を考慮して、適切にそれぞれの仕様を適切に設定することによって、全体としてバランスの取れた焦点調節を達成することができる。 Table 3 is a comparison table of the specification settings of the dedicated AF and the image sensor AF.

Considering the usage status of dedicated AF (re-imaging method) and image sensor AF (microlens method), by appropriately setting each specification appropriately, achieving a balanced focus adjustment as a whole Can do.

  In the distance measuring pupil distance (1), in the case of a long focus lens that generally has a large defocus amount, the exit pupil distance also becomes long. Since it is more advantageous for the vignetting of the focus detection light beam when the exit pupil distance and the distance measurement pupil distance of the interchangeable lens are aligned, the dedicated AF increases the distance detection pupil distance with an emphasis on large defocus detection. The image sensor AF shortens the distance measuring pupil distance for focus detection of a short focus lens with a small defocus amount. Further, by aligning the distance measurement pupil distances of the dedicated AF and the image sensor AF at the distance measurement pupil distance (2), the influence of the difference in distance measurement pupil distance on the focus detection result (focus detection caused by vignetting of the focus detection light beam). The degree of deterioration in accuracy) can be made uniform, and similar results can be obtained using either type of AF.

  In the distance measuring pupil F value (1), the distance measuring pupil F value of the dedicated AF is increased so that it can cope with a dark lens having a large open F value, and is darkened so that a large defocus amount can be detected. On the other hand, the distance-measuring pupil F value of the image sensor AF is reduced to make it brighter for high-precision focus detection of a bright lens having a small open F value, and adapted to detection of a small defocus amount only in the vicinity of the in-focus state.

  Further, by aligning the distance detection pupil F values of the dedicated AF and the image pickup element AF with the distance measurement pupil F value (2), the focus detection position of the dedicated AF and the image pickup element AF from the optical axis of the interchangeable lens 202 on the image pickup screen 100. When the distances to the focal point detection positions are equal, the degree of the influence of the difference in the distance measurement pupil F value on the focal point detection result (deterioration of the focal point detection accuracy caused by the vignetting of the focal point detection light beam) can be made uniform. Similar results can be obtained even if the AF method is used.

  Further, in the distance measurement pupil F value (3), the distance detection pupil F value of the dedicated AF is made smaller and brighter, and the detection capability of low luminance is improved. On the other hand, the distance-measuring pupil F value of the image sensor AF is increased and darkened, and is adapted to the super-high brightness focus detection capability (control of extremely short charge accumulation time).

  In the distance measuring pupil center of gravity (1), the distance AF center of gravity (opening angle) of the dedicated AF is reduced so that a large defocus amount can be detected. The focus detection is performed with high accuracy near the in-focus position. Further, in the distance measurement pupil center of gravity interval (2), the distance detection pupil center of gravity interval (opening angle) of the dedicated AF and the image sensor AF is made uniform so that the difference in distance detection pupil center of gravity (opening angle) is given to the focus detection result. The degree of influence can be made uniform, and the same result can be obtained using either type of AF.

  By aligning the positions of the dedicated AF and the AF area of the image sensor AF at the AF area position (1), it is possible to switch between the two methods depending on the situation for the same AF area. In addition, in the AF area position (2), it is possible to arrange more AF areas in the imaging screen 100 by making the positions of the dedicated AF and the AF area of the image sensor AF different. For example, an AF area is densely set near the center of the imaging screen 100 by the imaging element AF, and AF areas of dedicated AF are sparsely arranged around the imaging screen 100.

  In the number of AF areas (1), by using the dedicated AF and the image sensor AF to align the position of the AF area and the number of AF areas, it is possible to switch between the two methods depending on the situation for all the AF areas. it can. In addition, in the number of AF areas (2), the dedicated AF specializes in the focus detection of the multi-AF area and increases the number of AF areas, and the image sensor AF has a small number of AF areas, and the high precision of one AF area. Specialize in focus detection.

  In the detection pitch (1), the dedicated AF makes the detection pitch (sampling pitch) coarse so that the number of data does not increase even if the AF area length is increased in order to detect a large defocus amount. Prevents an increase and prevents a decrease in response. The image sensor AF makes the detection pitch finer in order to detect image displacement with high accuracy. In addition, in the detection pitch (2), by aligning the detection pitches of the dedicated AF and the image sensor AF, the extent of the influence of the difference in detection pitch on the focus detection result (image shift detection error, subject pattern selectivity, etc.) The same result can be obtained by using either type of AF.

  In the AF area length (1), the dedicated AF increases the length of the AF area to secure an image shift range for detecting a large defocus amount and enhances the capture of the subject. The length of the area is shortened to cope with a situation where the amount of image shift near the in-focus state is small, and pinpoint focus detection is enabled. Further, in the AF area length (2), by adjusting the lengths of the AF areas of the dedicated AF and the image sensor AF, the influence of the difference in the AF area length on the focus detection result (image shift detection error, The degree of selectivity of the subject pattern, etc. can be made uniform, and the same result can be obtained using either type of AF.

  In the AF area width (1), the dedicated AF increases the width of the AF area to secure light intensity at low luminance, and the image sensor AF can detect even finer subject patterns by reducing the width of the AF area. And Further, in the width (2) of the AF area, by aligning the widths of the AF areas of the dedicated AF and the image sensor AF, the influence of the difference in the width of the AF area on the focus detection result (image shift detection error, subject pattern The degree of selectivity and the like can be made uniform, and similar results can be obtained using either type of AF.

  In the color separation filter (1), by not using the color separation filter for the dedicated AF and the image sensor AF, the influence of the color separation filter on the focus detection result (subject pattern selectivity, etc.) can be eliminated. Similar results can be obtained even if the AF of this type is used.

  Further, in the color separation filter (2), a dedicated AF photoelectric conversion unit is not provided with a color separation filter (RGB color filter), and a light quantity at low luminance is secured, and a focus detection pixel of the image sensor AF. The color separation filter is arranged to improve the image quality by using the output of the focus detection pixel with color filter when interpolating the image signal at the position of the focus detection pixel from the output of the surrounding imaging pixels. By performing focus detection for each color, focus detection can be performed even for a subject that has a change in hue but no change in luminance.

  At the infrared cut wavelength (1), by aligning the cut wavelength of the infrared cut filter provided on the incident side of the dedicated AF and the image sensor AF, the influence of the infrared component included in the light beam coming from the subject on the focus detection result (Infrared aberration) can be eliminated, and a similar result can be obtained using either type of AF.

  In the infrared cut wavelength (2), the cut wavelength of the infrared cut filter provided on the incident side of the dedicated AF is irradiated with AF auxiliary light (the subject is irradiated to increase the light amount at low luminance. A long wavelength (red Infrared light is used to ensure focus detection performance at low luminance, and the cut wavelength of the infrared cut filter provided on the incident side of the image sensor AF is the infrared cut of the imaging pixel. In accordance with the characteristics, an error of infrared aberration is prevented, and the output of the focus detection pixel can be used as an image signal.

  FIG. 17 is a flowchart showing the focus detection operation. In the flowchart shown in FIG. 12, the dedicated AF is used in the coarse adjustment of the focus adjustment and the image sensor AF is used in the fine adjustment. Generally, this focus detection operation is a flowchart shown in FIG. In step 900, the power is turned on. In step 910, switching between dedicated AF and image sensor AF is determined according to the situation. If it is determined in step 910 that the dedicated AF is to be used, the process proceeds to step 920, the focus is adjusted using the dedicated AF, and then the process returns to step 910. If it is determined in step 910 that the image sensor AF is to be used, the process proceeds to step 930, focus adjustment is performed using the image sensor AF, and then the process returns to step 910.

専用ＡＦ（再結像方式）と撮像素子ＡＦ（マイクロレンズ方式）を撮像装置の使用状況を考慮して適切に切り換えることによって、全体としてバランスの取れた焦点調節を達成することができる。 The switching determination in step 910 is performed by making use of the characteristics of the dedicated AF (re-imaging method) and the image sensor AF (microlens method) so that the focus adjustment operation of the imaging apparatus is optimally performed as a whole. For example, it is performed based on the determination items (determination conditions) shown in Table 4.

By appropriately switching between the dedicated AF (re-imaging method) and the image sensor AF (microlens method) in consideration of the use state of the image pickup apparatus, it is possible to achieve a balanced focus adjustment as a whole.

  In the presence or absence of shutter release (imaging command), the following requirements are high before the shutter button release operation, so dedicated AF is used. (1) Focus adjustment is also performed on a subject that is greatly blurred due to composition change or the like. (2) Even when there are a plurality of objects in the imaging screen 100, focus adjustment is performed on an object that is likely to be a subject. (3) Focus adjustment is performed with emphasis on response over accuracy. (4) Focus adjustment is possible even at low luminance. On the other hand, after the release operation of the shutter button, there is a high demand for achieving high-precision focus adjustment immediately before imaging, so the imaging element AF is used.

  When the defocus amount is large, when the focus is adjusted to near the focus using the dedicated AF that can detect a large defocus amount. Switching to the image sensor AF capable of accurate focus adjustment.

  In continuous shooting and single shooting (1), the subject is likely to move during continuous shooting (continuous shooting at short intervals). A dedicated AF capable of responsive focus adjustment is used, and there are many situations where a still subject is imaged during single shooting (one shooting is performed by one release operation). An image sensor AF capable of accurate focus adjustment is used.

  In continuous shooting and single shooting (2), when the system of (3) in Table 2 is used, if dedicated AF is used, a mirror must be inserted and retracted in order to perform focus detection and imaging operations. High-speed continuous shooting is not possible. Therefore, an image sensor AF that does not require a mirror operation is used during focus detection and imaging during continuous shooting, and a dedicated AF that is advantageous for low luminance and large defocusing is used during single shooting.

  In moving images and still images (1), when the imaging device is in moving image shooting (video shooting) or in moving image shooting mode, the shooting target is likely to be a moving subject. Using dedicated AF that can be adjusted, and during still image shooting (still shooting) or in the still shooting mode, there is a high possibility that the shooting target is a stationary subject. Possible image sensor AF is used.

  In the case of using the system of (3) in Table 2 for moving images and still images (2), if dedicated AF is used, a mirror must be inserted and retracted in order to perform a focus detection operation and an imaging operation. I cannot shoot movies. Therefore, an image sensor AF that does not require a mirror operation is used during movie shooting (video shooting) or movie shooting mode, and low brightness or high brightness during still image shooting (still shooting) or still shooting mode. A dedicated AF advantageous for defocusing is used.

  When the luminance of the object scene is lower than a predetermined value, the dedicated AF that is strong against low luminance is used, and when the luminance is higher than the predetermined value, the image sensor AF capable of high-precision focus adjustment is used. The luminance of the object scene is calculated by the body CPU 214 based on the output of the image sensor 212. Of course, a dedicated photometry element and a photometry circuit may be provided to detect the luminance of the object scene.

  Whether the subject is moving or stationary can be determined from the time-series change in the focus detection result (defocus amount) in the movement and stationary of the subject. Therefore, when it is determined that the subject is moving, a dedicated AF capable of high-response focus adjustment with respect to the moving subject is used, and when it is determined that the subject is moving, a stationary subject In contrast, an image sensor AF capable of highly accurate focus adjustment is used.

  In the AF area mode, when the multi-AF area mode in which focus detection is performed simultaneously at a plurality of focus detection positions by an AF area mode selection operation member (not shown), focus detection is simultaneously performed at the plurality of focus detection positions. An image sensor capable of high-precision focus adjustment when a single AF area mode that performs focus detection at one focus detection position is selected using a dedicated AF that is easy to perform and has high response focus adjustment Use AF.

  When an AF area around the imaging screen 100 is selected at the AF area position (1), high image quality cannot be expected around the screen due to lens aberration, so focus is placed on response rather than accuracy for focus adjustment. When the dedicated AF is selected and the AF area at the center of the screen is selected, the image sensor AF capable of high-precision focus adjustment is selected to maximize the image quality.

  In the AF area position (2), when the AF area position of the dedicated AF and the AF area position of the image sensor AF are at different positions, the AF that is closest to the position designated by the user in the imaging screen 100 An area AF method (dedicated AF / image sensor AF) is used.

  In the AF mode, when the continuous AF mode in which the focus adjustment operation is continued once after focusing is selected in order to continue focusing on the moving subject by an AF mode selection operation member (not shown), Focus detection performance is stable and stable for stationary subjects by using a dedicated AF that has high focus adjustment performance for moving subjects and enables highly responsive focus adjustment. When the one-shot AF mode for performing the above is selected, an image sensor AF capable of high-precision focus adjustment is used.

  In the presence or absence of AF auxiliary light, when focus detection is performed by irradiating the subject with AF auxiliary light at low luminance, focus detection is performed without irradiating AF auxiliary light using dedicated AF that is stronger in lower luminance. When performing, an image sensor AF capable of highly accurate focus adjustment is used.

  In AF and MF, when an AF mode (automatic focus adjustment mode) in which focus is automatically adjusted by driving a lens according to a focus detection result is selected, a high response to a moving subject is obtained. MF mode (manual focus adjustment mode; automatic focus adjustment) where the focus is adjusted according to the focus detection result of the dedicated AF, and the user manually adjusts the focus of the lens according to the display. When the prohibit mode is selected, an image sensor AF capable of critical and highly accurate focus detection is used.

  In display, when an image is displayed on the electronic viewfinder in parallel with the focus adjustment operation (systems (1), (2), and (4) in Table 2), the focus adjustment is performed when a reduction display magnification is selected. The dedicated AF is used with emphasis on the response of the operation, and when the enlargement display magnification is selected, the imaging element AF is used with emphasis on the focusing accuracy. An operation member for selecting the image display magnification may be provided so that the enlargement or reduction display magnification can be selected.

  In the lens open F value, when the aperture open F value of the mounted interchangeable lens is dark, a dedicated AF with a dark ranging pupil F value is used to prevent the focus detection accuracy from being lowered due to the focus detection light beam being lost. When the aperture F value of the mounted interchangeable lens is bright, the imaging element AF is used that has a bright distance-measuring pupil F value and enables high-precision focus detection. Note that information such as the full aperture F value of the interchangeable lens is transmitted from the lens drive control circuit 206 to the body CPU 214.

  If the focal length of the mounted interchangeable lens is long at the lens focal length, use a dedicated AF with a long distance pupil distance and a wide defocus detection range, and if the mounted interchangeable lens has a short focal length, An image sensor AF having a short distance pupil distance and high focus detection accuracy is used. Information such as the focal length of the interchangeable lens is transmitted from the lens drive control circuit 206 to the body CPU 214.

  In the interchangeable lens aperture control F value, when the aperture F value at the time of imaging (control F value) is dark, high focus adjustment accuracy is unnecessary because the depth of focus is deep. When AF is used and the control F value is bright, the imaging element AF is used because high focus detection accuracy is required. Note that the aperture control F value of the interchangeable lens is obtained by exposure control calculation in the body CPU 214.

  When the shutter speed (exposure time) at the time of imaging is fast (long) at the shutter speed, the subject field is dark, so the dedicated AF is used to ensure the response of the focus adjustment operation, and the shutter speed (exposure at the time of imaging) When the time is slow (short), the image sensor AF is used with emphasis on focus adjustment accuracy. The shutter speed is obtained by the exposure control calculation of the body CPU 214.

  If the sensitivity at the time of imaging (amplification of the imaging pixel output of the imaging device) is high, the subject field is dark, so dedicated AF is used to ensure the response of the focus adjustment operation, and the sensitivity at the time of imaging Is low, the image sensor AF is used with emphasis on focus adjustment accuracy. The imaging sensitivity is set by a sensitivity setting operation member (not shown), and the amplification degree of the imaging pixel output of the imaging device is selected according to the set imaging sensitivity.

  When shooting with a strobe (subject illumination) and using a dedicated AF that is more robust to lower brightness and shooting without illuminating illumination when shooting with a strobe that illuminates the subject with illumination light. Uses an image sensor AF capable of high-precision focus adjustment. Further, when the flash photography is prohibited by the flash photography selection member for setting the permission or prohibition of the flash photography, the image sensor AF is used, and when the flash photography is permitted, the dedicated AF is used.

  In self-timer shooting, if the self-timer shooting mode for executing imaging after a predetermined time from the shooting instruction is selected by a shooting mode selection operation member (not shown), there is a high possibility that the subject is a stationary subject. When the image sensor AF capable of accurate focus adjustment is used and the self-timer shooting mode is not selected, there is a high possibility that the subject is a moving subject, and therefore dedicated AF suitable for focus adjustment of the moving subject is used.

  In hand-held shooting and fixed shooting, it is highly possible that the subject is a stationary subject when using a tripod, etc., so use the image sensor AF that allows highly accurate focus adjustment. Therefore, a dedicated AF suitable for adjusting the focus of the moving subject is used. Note that whether or not the imaging device is fixed is determined according to the attachment of a tripod or the output of an angular velocity sensor or an acceleration sensor built in the imaging device.

  Suitable for shooting moving subjects with a shooting mode selection operation member (not shown) in shooting mode in which shooting conditions (aperture value, shutter speed, sensitivity) are set as a set in the shooting mode. When a sport mode is selected, dedicated AF suitable for adjusting the focus of a moving subject is used. When a portrait mode suitable for capturing a still subject is selected, high-precision focus adjustment is performed. Possible image sensor AF is used.

専用ＡＦと撮像素子ＡＦでは同じ像ズレ検出アルゴリズム（（１）〜（６）式など）を用いているが、パラメータをうまく設定することにより、撮像装置全体としての焦点調節動作のパフォーマンスを向上させることができる。 Table 5 is a comparison table of AF algorithm parameters for the dedicated AF and the image sensor AF.

The same image shift detection algorithm (such as equations (1) to (6)) is used in the dedicated AF and the image sensor AF, but the performance of the focus adjustment operation of the entire image pickup apparatus is improved by setting the parameters well. be able to.

  In the defocus amount detection range, the defocus amount detection range is determined by the image shift limit (p, q) in equation (1). In the dedicated AF, p is made smaller and q is made larger in order to enable detection over a wide range. Since the image sensor AF is used near the in-focus position, p is increased and q is decreased to narrow the image shift range, and the detection range is narrowed to shorten the calculation time.

  When the minimum correlation amount C (x) in (3) is equal to or greater than the threshold value in the threshold value for determining the image displacement detection failure, the threshold value is determined to be unreliable. Set to be more severe. That is, the threshold value for the dedicated AF is set larger than the threshold value for the image sensor AF. In this way, more accurate focus detection can be performed. Since the value of the minimum correlation amount C (x) depends on the number of data used for the correlation calculation, the value of the minimum correlation amount C (x) is normalized by the number of data used for the correlation calculation. Although it is determined that there is no reliability when the parameter SLOP in the equation (5) is less than or equal to the threshold value, this threshold value is set so that the image sensor AF is more severe than the dedicated AF. In this way, more accurate focus detection can be performed. Since the value of the parameter SLOP also depends on the number of data used for the correlation calculation, the value of the parameter SLOP is standardized by the number of data used for the correlation calculation.

  In the in-focus recognition range, the in-focus detection range is a range of defocus amounts that are regarded as in-focus in step 150 and step 210 of the flowchart shown in FIG. 12, and in the case of dedicated AF, this range is set wider. The lens is quickly driven near the in-focus state so that the shutter release can be received. In the case of the image sensor AF, the in-focus recognition width is narrowed so that high-precision in-focus is achieved at the time of imaging.

  In the in-focus area, the in-focus area is recognition of the subject supplement area in step 140 of the flowchart shown in FIG. 12, and in the case of dedicated AF, it is suitable for performing focus detection simultaneously at a plurality of focus detection positions. Therefore, at the initial stage of focus detection, focus detection is performed in a plurality of AF areas by dedicated AF, and a predetermined algorithm is applied to the obtained plurality of defocus amounts to identify an AF area that seems to capture the subject. To do. In the case of the image sensor AF, since it is not suitable for performing focus detection at a plurality of focus detection positions at the same time, highly accurate focus detection is performed in the AF area selected by the dedicated AF.

  In the offset amount, the offset amount is a fine adjustment amount with respect to the calculated defocus amount as described in step 440 shown in FIG. In the case of the image sensor AF, since the focus detection pixel and the image capture pixel are arranged on the same image sensor substrate, the detected defocus amount directly corresponds to the focus adjustment state of the image on the image sensor. ing. In the case of the dedicated AF, since it is incorporated in the camera body as a unit separate from the image sensor, it is necessary to add an offset amount in order to finally achieve focusing on the image sensor.

  If the distance measurement F values of the image sensor AF and the dedicated AF are different, the focusing position of the image sensor AF and the dedicated AF changes depending on the optical characteristics (spherical aberration, etc.) of the photographing optical system, resulting in an offset. The amount also changes. In such a case, the offset amount is changed based on the optical characteristic data included in the lens information.

  Similarly, when the open F value of the interchangeable lens is darker than the distance measurement F value of the image sensor AF or the dedicated AF, vignetting occurs in the focus detection light beam, and the focus position of the image sensor AF and the dedicated AF changes, As a result, the offset amount also changes. In such a case, the offset amount is changed based on the open F value included in the lens information.

  Furthermore, it is also possible to periodically detect the focus on the same subject simultaneously with the dedicated AF and the image sensor AF, and update the calculated difference between the defocus amounts as a new offset amount. In this way, the positions of the image sensor AF and the dedicated AF change according to the environment such as humidity and temperature, or change with time due to mechanical wear of a movable member such as a sub-mirror that is a light beam switching means. Can also handle cases.

  In Table 5, when the dedicated AF is used in the initial stage of focus adjustment and the image sensor AF is used in the final stage of focus adjustment, the dedicated AF and imaging are performed so that the focus adjustment operation is performed with high response and high accuracy as a whole. The AF algorithm parameters of the element AF are made different. When the focus detection positions of the dedicated AF and the image sensor AF are different, the parameters shown in Table 5 are aligned so that the focus detection performance does not change greatly regardless of which focus detection position (AF area) is selected.

  Other modifications will be described. In the half mirror, the half mirror shown in FIG. 1 and FIG. 18 is not limited to a glass plate formed with a semipermeable membrane, and any light splitting means for splitting light may be used. For example, two triangular prism blocks may be bonded to each other at an inclined surface, and a multilayer film having a half mirror function may be formed on the bonded surface. In this way, back surface reflection that occurs in the case of a glass plate can be prevented, and focus detection performance and image quality are improved. Moreover, you may comprise a half mirror by the pellicle mirror on a thin film. In this way, back surface reflection that occurs in the case of a glass plate can be prevented, and focus detection performance and image quality are improved.

  Furthermore, instead of dividing the amount of light, a spectral mirror that performs wavelength division may be employed. For example, a spectroscopic mirror in which the imaging element AF receives visible light and the dedicated AF receives infrared light can be used. In this way, the amount of light during imaging can be earned. A polarizing half mirror may be used in which a circular polarizing filter is disposed for incident light, and light that has been polarized in a specific direction out of light that has passed through the circular polarizing filter is selectively transmitted or reflected. By doing so, it is possible to prevent fluctuations in transmittance and reflectance due to wavelength, which are caused when a half mirror is formed of a multilayer film.

  In the imaging and focus detection apparatus, the imaging and focus detection apparatus is not limited to a digital still camera including an interchangeable lens and a camera body. It can also be applied to lens-integrated digital still cameras and video cameras. The present invention can also be applied to a small camera module built in a mobile phone or the like.

  As described above, according to an embodiment, a pair of images formed by a pair of light fluxes that capture an image formed by the imaging optical system and pass through a pair of pupil regions of the imaging optical system. An imaging and focus detection means for detecting the focus adjustment state of the imaging optical system based on the amount of deviation and a focus detection means for detecting the focus adjustment state of the imaging optical system are provided, and detection by the imaging and focus detection means and the focus detection means Based on the results, the focus of the imaging optical system was adjusted. Since the imaging and focus detection unit has a phase difference type focus detection function, even when the focus detection function of the imaging and focus detection unit is used, highly responsive focus adjustment can be realized, and the moving subject can be controlled. Can adjust the focus with high precision.

  In addition, according to the embodiment, the light beam splitting unit is fixed because the light beam splitting unit that reflects the light beam from the subject that has passed through the imaging optical system to the imaging and focus detection unit and transmits the light beam to the focus detection unit is provided. Thus, it is not necessary to evacuate from the optical path of the photographic optical system at the time of imaging, and imaging with a small release time lag can be performed. Further, since the image pickup and focus detection means picks up an image with the reflected light of the light beam splitting means, there is no image deterioration due to transmission through the light beam splitting means. Further, the focus adjustment can be performed by operating the focus detection means in parallel with the imaging operation of the imaging and focus detection means.

  According to one embodiment, since the light beam from the subject that has passed through the imaging optical system is provided with the light beam splitting unit that transmits to the imaging and focus detection unit and reflects to the focus detection unit, the beam splitting unit is fixed. There is no need to evacuate from the optical path of the imaging optical system during imaging, and imaging with a small release time lag can be performed. Further, since the imaging and focus detection means is arranged in the optical axis direction of the imaging optical system, the thickness of the imaging apparatus in the optical axis direction can be reduced, and a compact camera body can be provided. Further, the focus adjustment can be performed by operating the focus detection means in parallel with the imaging operation of the imaging and focus detection means.

  According to one embodiment, the optical path switching means is disposed so as to be able to be inserted into and retracted from the optical path of the imaging optical system, and the imaging and focus detection means detects the light beam from the subject that has passed through the imaging optical system in the retracted state. And an optical path switching unit that reflects the light beam from the subject that has passed through the imaging optical system in the inserted state to the focus detection unit. At the time of imaging, the optical path switching means is retracted from the imaging optical path, and the imaging and focus detection means directly receives the imaging light flux from the subject, so that a high quality image can be obtained. Further, since the light flux from the subject is not divided into the imaging / focus detection means and the focus detection means, it is advantageous for securing the light quantity at low luminance.

  According to one embodiment, the image pickup and focus detection means includes an image pickup element in which an image pickup pixel and a focus detection pixel are arranged on the same substrate, and the focus detection pixel is a pair for one microlens. It was made to have a photoelectric conversion part. Since the focus detection method of the image pickup and focus detection means is realized by the microlens method, the image pickup and focus detection means can be configured compactly, and finally the focus detection can be performed on the same surface as the image pickup surface. It is possible to perform focus detection with high accuracy after removing an alignment error between the detection means and the focus detection means and an arrangement error of the imaging and focus detection means itself.

According to one embodiment, the focus detection unit detects a focus adjustment state of the imaging optical system based on an image shift amount of the pair of images formed by the pair of light beams passing through the pair of pupil regions of the imaging optical system. The so-called phase difference detection method was adopted. Even when the focus detection function based on the phase difference detection method of the focus detection means and the focus detection function based on the phase difference detection method of the imaging and focus detection means are switched according to the situation, the focus based on the same principle, that is, the phase difference detection method Since detection is performed, there is no significant difference in focus detection results, and smooth and natural switching is possible.
In addition, since the focus detection function of the focus detection means and the focus detection function of the imaging and focus detection means are the same phase difference detection method, the configuration of the phase difference detection method and various parameters of the phase difference detection algorithm are used for each focus detection function. By setting according to the situation in which the lens is used, the performance of the focus detection function can be complemented, and the focus detection function can be switched according to the situation to improve the focus detection performance as a whole.
In addition, since the focus detection function of the focus detection unit and the focus detection function of the imaging and focus detection unit use the same phase difference detection method, the focus difference can be obtained by aligning the configuration of the phase difference detection method and various parameters of the phase difference detection algorithm. It is possible to improve the coincidence of the detection results and prevent an unnatural operation at the time of switching.
Furthermore, the phase difference detection method of the focus detector means is realized by the re-imaging method, and the focus detection method of the imaging and focus detection means is realized by the microlens method, so that the best focus detection as a whole by taking advantage of each method. A system can be realized.

  According to the embodiment, when the focus of the imaging optical system is adjusted, the imaging optical system is roughly adjusted based on the focus detection result of the focus detection unit, and the imaging optical is based on the focus detection result of the imaging and focus detection unit. Since the system is finely adjusted, it is possible to achieve highly responsive focus adjustment based on the detection result of the focus detection means and highly accurate focus adjustment based on the detection result of the imaging and focus detection means. You can focus quickly and accurately.

  According to one embodiment, when adjusting the focus of the imaging optical system, the focus adjustment of the imaging optical system is performed based on the detection result of the focus detection unit until the imaging operation is started, and after the imaging operation is started Since the focus adjustment of the imaging optical system is performed based on the detection result of the imaging and focus detection means, the focus adjustment with high responsiveness based on the detection result of the focus detection means and the detection result of the imaging and focus detection means are used. High-precision focus adjustment can be realized, and the intended subject can be focused quickly and accurately.

  According to one embodiment, an image formed by the imaging optical system is captured and imaged based on an image shift amount of the pair of images formed by the pair of light beams passing through the pair of pupil regions of the imaging optical system. An imaging and focus detection means for detecting the focus adjustment state of the optical system and a distance measuring means for detecting the distance to the subject are provided, and the focus of the imaging optical system is based on the detection results of the imaging and focus detection means and the distance measurement means. Adjustment was made. Since the imaging and focus detection unit has a phase difference type focus detection function, even when the focus detection function of the imaging and focus detection unit is used, highly responsive focus adjustment can be realized, and the moving subject can be controlled. Can adjust the focus with high precision.

  According to an embodiment, when adjusting the focus of the imaging optical system, coarse adjustment of the imaging optical system is performed based on the detection result of the distance measuring unit, and fine adjustment of the imaging optical system is performed based on the detection result of the imaging and focus detection unit. Because adjustment is performed, it is possible to achieve highly responsive focus adjustment based on the detection result of the distance measuring means and high-precision focus adjustment based on the detection result of the imaging and focus detection means, and quickly and accurately on the intended subject. You can focus.

  According to one embodiment, when adjusting the focus of the imaging optical system, the focus adjustment of the imaging optical system is performed based on the detection result of the distance measuring means until the imaging operation is started, and after the imaging operation is started Since the focus adjustment of the imaging optical system is performed based on the detection result of the imaging and focus detection means, the focus adjustment with high responsiveness based on the detection result of the distance measuring means and the detection result of the imaging and focus detection means High-precision focus adjustment can be realized, and the intended subject can be focused quickly and accurately.

The figure which shows the structure of the digital still camera of one embodiment Front view showing detailed configuration of image sensor Cross-sectional view of imaging pixels Cross section of focus detection pixel The figure explaining the pupil division type phase difference detection method by a micro lens system Front view showing the relationship between projection areas (ranging pupils) of a pair of photoelectric conversion units of focus detection pixels on the exit pupil plane The figure which shows the circuit structure of an image sensor The figure which shows the detailed structure of the focus detection sensor corresponding to FIG. The figure which shows the ranging pupil on the exit pupil plane in the re-imaging method The figure which shows the circuit structure of the image sensor of the focus detection sensor used by exclusive AF Diagram showing the focus detection position on the shooting screen 1 is a flowchart showing the operation of the digital still camera (imaging device) shown in FIG. Flow chart showing image shift amount detection operation Flow chart showing operation for converting image shift amount to defocus amount Flowchart showing subject capture AF area recognition operation Diagram showing focus detection calculation algorithm Flow chart showing focus detection operation The figure which shows the other example of arrangement | positioning of a focus detection sensor (dedicated AF) and an image sensor (image sensor AF). The figure which shows the other example of arrangement | positioning of a focus detection sensor (dedicated AF) and an image sensor (image sensor AF). The figure which shows the other example of arrangement | positioning of a focus detection sensor (dedicated AF) and an image sensor (image sensor AF).

Explanation of symbols

10, 50, 60... Micro lens, 12, 13, 52, 53, 62, 63 .. photoelectric conversion unit, 29 .. semiconductor circuit board, 205 .. half mirror, 206 .. lens drive control circuit, 207. ..Focus detection sensor 202 .. Interchangeable lens 210.. Focusing lens 212.. Image sensor 214 214 Body CPU 231 Sub mirror 240 External light range finder 310 311 ..Focus detection pixel

Claims (15)

A focus adjustment state of the imaging optical system based on an image shift amount of a pair of images formed by a pair of light beams passing through a pair of pupil regions of the imaging optical system while capturing an image formed by the imaging optical system Imaging and focus detection means for detecting
Focus detection means for detecting a focus adjustment state of the imaging optical system;
A focus adjustment apparatus comprising: the image pickup and focus detection means; and a focus adjustment means for performing focus adjustment of the image pickup optical system based on a detection result by the focus detection means. The focus adjustment apparatus according to claim 1,
A focus adjusting apparatus comprising: a light beam splitting unit that reflects a light beam from an object that has passed through the imaging optical system to the imaging and focus detection unit and transmits the beam to the focus detection unit. The focus adjustment apparatus according to claim 1,
A focus adjusting apparatus comprising: a light beam splitting unit that transmits a light beam from an object transmitted through the imaging optical system to the imaging and focus detection unit and reflects the beam to the focus detection unit. The focusing apparatus according to claim 2 or 3,
A focus adjusting apparatus using a half mirror that prevents back surface reflection as the light beam splitting means. The focus adjustment apparatus according to claim 1,
An optical path switching unit disposed so as to be able to be inserted into and retracted from the optical path of the imaging optical system, wherein the light beam from the subject that has passed through the imaging optical system in the retracted state is guided to the imaging and focus detection unit, and is inserted And a light path switching means for reflecting the light beam from the subject transmitted through the imaging optical system to the focus detection means. In the focus adjustment apparatus according to any one of claims 1 to 5,
The image pickup and focus detection unit includes an image pickup device in which an image pickup pixel and a focus detection pixel are arranged on the same substrate. The focusing apparatus according to claim 6, wherein
The focus adjustment device, wherein the focus detection pixel has a pair of photoelectric conversion units for one microlens. The focus adjustment apparatus according to any one of claims 1 to 7,
The focus detection unit detects a focus adjustment state of the imaging optical system based on an image shift amount of a pair of images formed by a pair of light beams passing through a pair of pupil regions of the imaging optical system. Focusing device. The focus adjustment device according to claim 8.
The focus detection means includes a pair of re-imaging optical systems that re-image an image formed on a predetermined focal plane of the imaging optical system, and a pair of images re-imaged by the pair of re-imaging optical systems. And an image sensor for detecting a focus adjustment device. The focus adjustment apparatus according to any one of claims 1 to 9,
The focus adjustment unit performs coarse adjustment of the imaging optical system based on the detection result of the focus detection unit, and performs fine adjustment of the imaging optical system based on the detection result of the imaging and focus detection unit. Focus adjustment device characterized. The focus adjustment apparatus according to any one of claims 1 to 9,
The focus adjustment unit performs focus adjustment of the imaging optical system based on the detection result of the focus detection unit until a shooting operation is started, and after the shooting operation is started, detection of the imaging and focus detection unit A focus adjustment apparatus that performs focus adjustment of the imaging optical system based on a result. A focus adjustment state of the imaging optical system based on an image shift amount of a pair of images formed by a pair of light beams passing through a pair of pupil regions of the imaging optical system while capturing an image formed by the imaging optical system Imaging and focus detection means for detecting
Ranging means for detecting the distance to the subject;
A focus adjustment apparatus comprising: the image pickup and focus detection means; and a focus adjustment means for adjusting a focus of the image pickup optical system based on a detection result by the distance measurement means. The focusing device according to claim 12,
The focus adjusting unit performs rough adjustment of the imaging optical system based on the detection result of the distance measuring unit, and performs fine adjustment of the imaging optical system based on the detection result of the imaging and focus detection unit. Focus adjustment device characterized. The focusing device according to claim 12,
The focus adjusting means adjusts the focus of the imaging optical system based on the detection result of the distance measuring means until the photographing operation is started, and the imaging and focus detecting means detects after the photographing operation is started. A focus adjustment apparatus that performs focus adjustment of the imaging optical system based on a result.   An imaging apparatus comprising the focus adjustment apparatus according to claim 1.

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