JP2011112731A - Image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image pickup device capable of performing focus detection in a wider range by using a pixel for the focus detection of an imaging device. <P>SOLUTION: A digital camera includes: the imaging device 30 that has the pixel 31 for focus detection; an image display section 46 that inputs a focus detection target position P; an imaging device drive part 29 that drives the imaging device 30 in a direction vertical to the optical axis; a system control part 20 that controls the drive of the imaging device by the imaging device drive part so that the focus detection target position may overlap the pixel for focus detection; and a focus detecting part 35 in the imaging device to which the focus detection at the focus detection target position is performed by the pixel for focus detection after the focus detection target position overlap the pixel for focus detection. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an imaging apparatus.

  In Patent Documents 1 and 2, focus detection pixels having a pupil division function are provided in part of the pixel array of the image sensor, and phase difference focus detection on the imaging surface is possible.

JP 2000-156823 A JP 2000-292686 A

  However, the ratio of focus detection pixels in the pixel array is limited in order to maintain the imaging performance of the imaging device. For this reason, in both Patent Documents 1 and 2, the target position (hereinafter referred to as “focus detection target position”) for performing focus detection set on the imaging surface (pixel array) of the image sensor deviates from the focus detection pixels. In other words, there was a problem that focus detection could not be performed.

  An object of the present invention is to provide an imaging device capable of focus detection in a wider range by using focus detection pixels of an image sensor.

  An imaging apparatus according to an aspect of the present invention includes an imaging element that includes an imaging pixel that photoelectrically converts an optical image and a focus detection pixel that performs phase difference focus detection, and a target that performs focus detection on the imaging surface of the imaging element. An input unit for inputting a position, an image sensor driving unit for driving the image sensor in a direction perpendicular to the optical axis, and driving of the image sensor by the image sensor driving unit so that the target position overlaps the focus detection pixel. And a focus detection unit that performs focus detection of the target position by the focus detection pixel after the target position overlaps the focus detection pixel. Instead of driving the image sensor by the image sensor driver, the optical camera shake correction lens may be driven.

  ADVANTAGE OF THE INVENTION According to this invention, the imaging device which can detect a focus in a wider range using the focus detection pixel of an image pick-up element by providing the means to move the position of a focus detection pixel can be provided.

It is a block diagram of the single-lens reflex digital camera (imaging device) common to Examples 1-3. It is a schematic diagram of the imaging surface of the imaging device shown in FIG. 6 is a flowchart for explaining an operation from when the camera according to the first embodiment enters live view mode until shooting is performed. It is a figure explaining the effect of the movement of the correction lens of the camera-shake correction lens unit shown in FIG. 1, and the movement of an image sensor. It is a figure which shows the range which can detect the focus of the image pick-up element shown in FIG. 6 is a flowchart from when the camera according to the second embodiment enters live view mode to when shooting is performed. 10 is a flowchart from the start of moving image shooting to the end of moving image shooting by the camera of the third embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram of a single-lens reflex digital camera (imaging device) common to the first to third embodiments. The single-lens reflex digital camera is configured such that the lens unit 10 indicated by a dotted line can be attached to and detached from (replaceable with) a camera body including other components. However, the imaging apparatus of the present invention is not limited to a single-lens reflex digital camera, and can be widely applied to imaging apparatuses (digital cameras and digital video cameras) including an imaging element having focus detection pixels.

  The lens unit 10 includes a photographing lens (not shown) that forms a subject image, a lens control unit 11, a camera shake correction lens unit 12, an aperture unit 13, and a focus lens unit 14.

  The lens control unit 11 includes a processor such as a CPU or MPU, and controls the operation of each unit of the lens unit 10. The lens control unit 11 communicates with the system control unit 20 to control the camera shake correction lens unit 12, the aperture unit 13, and the focus lens unit 14.

  The camera shake correction lens unit 12 is an optical camera shake correction unit that corrects the optical axis by moving a correction lens equipped with a vibration gyroscope in a direction to cancel the shake (lens shift method).

  The aperture unit 13 has an aperture that adjusts the amount of light by changing the aperture value.

  The focus lens unit 14 has a focus lens that moves in the optical axis direction and performs automatic focus adjustment (AF). In AF, the lens control unit 11 receives a drive command including the drive direction, drive amount, and drive speed of the focus lens from the system control unit 20, and drives the focus lens in the optical axis direction to perform focus control. Thereby, a subject image is formed on the image sensor 30.

  The camera body includes a system control unit 20, a quick return mirror 21, a penta roof prism 22, a photometry unit 23, a focus detection unit 24, an acceleration sensor 25, a shift amount storage memory 26, and a release button 27. The camera body includes an image sensor driving unit 29, an image sensor 30, an in-image sensor focus detection unit 35, a timing generation circuit (TG) 40, an A / D conversion unit 41, an image processing unit 42, a memory control unit 44, and a display. A control unit 45 and an image display unit 46 are provided.

  The system control unit 20 is a processor such as a CPU or MPU that controls the entire camera. The system control unit 20 sends to the lens control unit 11 a correction amount for the camera shake correction lens unit 12, a drive amount for the aperture unit 13, a drive command for the focus lens unit 14, a stop command, a drive amount, a required drive speed, and various lens-side values. Send a data transmission request. The lens control unit 11 transmits to the system control unit 20 status information of each part of the lens unit 10 and various parameters on the lens side such as an open F value and a focal length. Further, the system control unit 20 fixes the display content of the image display unit 46 during driving of the image sensor 30 or the correction lens (fixed to another image or stops the display itself).

  The quick return mirror 21 is disposed obliquely with respect to the optical axis in the photographing optical path, and retracts to the mirror down position (first position) shown in FIG. 1 for guiding the light beam from the subject to the viewfinder optical system and out of the photographing optical path. It is possible to move between the mirror up position (second position).

  The light beam reflected by the quick return mirror 21 at the first position reaches the eyes of the photographer through the finder optical system including the penta roof prism 22 and is measured by the light meter 23 by the light beam guided to the penta roof prism 22. Done. Further, the light beam that has passed through the semi-transmissive portion of the quick return mirror 21 is guided to the focus detection unit 24.

  When the quick return mirror 21 is in the second position during live view display or moving image shooting, the light flux from the lens unit 10 reaches the image sensor 30 via a shutter (focal plane shutter) (not shown) and an optical filter. . At this time, the focus detector 35 in the image sensor performs focus detection. The live view mode is a mode that allows the photographer to check the optical image formed by the photographing lens on the image display unit 46, and can be set from a mode setting unit (not shown).

  The acceleration sensor 25 detects camera shake. The shift amount storage memory 26 is used to store the shift amount of the image sensor 30 or the shift amount of the camera shake correction lens unit 12.

  The release button 27 is a two-stage switch for instructing photometry, start of focus detection, and photographing. The state where the release button 27 is lightly pushed down to the first level is called “half-press” (SW1). In this state, photometry and focus detection are performed. Pressing halfway down to the second level is called “full press” (SW2), and shooting is performed by pressing fully.

  The AF start button 28 is an AE lock / FE lock button for performing AE (automatic exposure) / FE lock shooting during normal shooting, performs AF during live view, and reduces the captured image and indexes during playback. Is displayed. Accordingly, different functions are executed during shooting and playback.

  The image sensor driving unit 29 horizontally and vertically drives each imaging pixel of the image sensor 30 based on a signal from the TG 40 that determines the overall drive timing. Thereby, the subject image is photoelectrically converted to generate and output an image. The image sensor driving unit 29 performs optical camera shake correction by driving the image sensor 30 (image sensor) in a direction perpendicular to the optical axis (image sensor shift method).

  The image sensor 30 is composed of a CCD or a CMOS, and has a pixel array composed of a plurality of imaging pixels that photoelectrically convert an optical image and a plurality of focus detection pixels that perform phase difference type focus detection on the imaging surface. The image pickup device 30 is configured so that, for example, a two-dimensional single-plate color sensor in which a Bayer array primary color mosaic filter is formed on-chip can be used for independent output of all pixels. Each imaging pixel receives a light beam passing through the entire exit pupil of the imaging lens, photoelectrically converts it, and outputs a signal charge for imaging.

  Each focus detection pixel receives light passing through a partial region of the exit pupil of the photographing lens. The plurality of focus detection pixels as a whole can receive light passing through the entire exit pupil of the photographing lens. The focus detection pixels are discretely arranged in the imaging region, but the ratio in the pixel array is limited. When the focus detection pixels are arranged, a pair of G pixels arranged diagonally out of the pixels in 2 rows × 2 columns are left as photographing pixels, and a pair of focus detections in which the R pixel and the B pixel are divided into pupils. Replace with a pixel.

  The imaging element focus detection unit 35 has focus detection pixels, and detects the phase difference between the two light beams divided by the microlens and the wiring layer as disclosed in Patent Document 1 (that is, the position is detected). Perform focus detection (by phase difference method). In this case, photometry is performed on the imaging surface of the image sensor 30.

  The TG 40 supplies a clock signal and a control signal to the image sensor 30 and the A / D converter 41 and is controlled by the system controller 20. The A / D conversion unit 41 converts the optical image into an electrical signal.

  The image processing unit 42 performs predetermined image processing such as pixel interpolation processing and color conversion processing on the image data from the A / D conversion unit 41 or the memory control unit 44. The sound processing unit 43 performs predetermined sound processing such as A / D conversion, gain adjustment, noise adjustment, and impact sound detection on sound data from a microphone (not shown) or the memory control unit 44.

  The memory control unit 44 controls the TG 40, the A / D conversion unit 41, the image processing unit 42, and the display control unit 45. Data output from the A / D conversion unit 41 is written into a memory (not shown) via the image processing unit 42, the memory control unit 44, or directly from the data of the A / D conversion unit 41 via the memory control unit 44. It is.

  The image display unit 46 is a touch panel image display unit (liquid crystal panel) that functions as an input unit for confirming and selecting a captured image, selecting / setting a menu function, and inputting a focus detection target position during live view. However, a target position for focus detection may be input and set on another imaging unit (dial, button, etc.) (not shown) on the imaging surface (pixel array) of the imaging device.

  FIG. 2 is a schematic diagram illustrating an array of focus detection pixels 31 of the image sensor 30. In FIG. 2, fifteen focus detection pixels 31 are schematically provided, and imaging pixels are omitted. In the present embodiment, in the live view mode, when the focus detection target position P that the photographer desires to detect focus is shifted from any of the positions of the plurality of focus detection pixels 31, the shift is eliminated. The correction lens of the shake correction lens unit 12 is moved.

  FIG. 3 is a flowchart for explaining an operation from when the system control unit 20 enters the live view mode to when shooting is performed. In FIG. 3, “S” stands for a step. In the live view mode, AF is activated when the image display unit 46 is touched or when the AF start button 28 is operated.

  When the live view starts (S101), the system control unit 20 determines whether SW2 of the release button 27 is ON (S102). If it is determined that SW2 is ON (Yes in S102), the system The control unit 20 performs imaging (S117).

  On the other hand, when the system control unit 20 determines that SW2 is OFF (No in S102), the system control unit 20 determines whether or not the focus detection target position P is input to the image display unit 46 (S103). .

  When the system control unit 20 determines that the focus detection target position P has been input (Yes in S103), the system control unit 20 selects the focus detection pixel 31 closest to the focus detection target position P, and The amount of deviation from the focus detection target position P is calculated (acquired) (S104). The reason why the focus detection pixel 31 closest to the focus detection target position P is used is that the moving distance of the image sensor 30 is short, so that the focus detection time is shortened. The system control unit 20 calculates the correction movement (shift) direction and the correction movement amount of the camera shake correction lens unit 12 from this shift amount (S104), and stores them in the shift amount recording memory 26.

  Next, the system control unit 20 turns off the image display unit 46 (S105). Since the blurred image is not displayed when the correction lens is moved, it is possible to eliminate the discomfort given to the photographer. However, instead of turning off the image display unit 46, the immediately preceding image may be displayed, or the display may be continued if the amount of blur is small (that is, if the amount is less than the threshold).

  Next, the system control unit 20 drives the correction lens of the camera shake correction lens unit 12 vertically and horizontally so that the focus detection target position P overlaps the focus detection pixel 31 by the correction movement amount acquired in step S104. (S106). As a result, as shown in FIG. 4A, the image circle C moves from the dotted line to the solid line, and the focus detection target position P overlaps with one of the focus detection pixels 31 of the image sensor 30.

  Next, the system control unit 20 controls the focus detector 35 in the image sensor to perform focus detection using the focus detection pixel 31 of the image sensor 30 (S107). Next, the system control unit 20 returns the correction lens of the camera shake correction lens unit 12 to the original position via the lens control unit 11 (S108). As a result, before focus adjustment after focus detection, the focus detection target position P and the focus detection pixel 31 return to the state before the optical image stabilization lens is driven.

  Next, the system control unit 20 turns on the image display unit 46 (S109). When the image display unit 46 displays an image while the correction lens of the camera shake correction lens unit 12 is moving, the correction lens moves in accordance with normal camera shake correction control and correction movement in S106. It is only necessary to add the movements.

  Next, the system control unit 20 drives the focus lens unit 14 based on the focus detection result in S107 (S110).

  Next, the system control unit 20 determines whether SW2 of the release button 27 is ON (S111). If the system control unit 20 determines that SW2 is ON (Yes in S111), the system control unit 20 performs imaging (S117). On the other hand, when the system control unit 20 determines that SW2 is not ON (No in S111), the flow returns to S103.

  On the other hand, when the system control unit 20 determines that the focus detection target position P has not been input (No in S103), the system control unit 20 determines whether the AF start button 28 has been operated (S112).

  If the system control unit 20 determines that the AF start button 28 has not been operated (No in S112), the flow proceeds to S102. If the system control unit 20 determines that the AF start button 28 has been operated (Yes in S112), the focus detection target position P is automatically selected (S513).

  Next, the system control unit 20 controls the in-image sensor focus detection unit 35 to perform focus detection using the focus detection pixels 31 of the image sensor 30 at the selected focus detection target position P. (S114).

  Next, the system control unit 20 drives the focus lens unit 14 based on the focus detection result in S114 (S115). Next, the system control unit 20 determines whether SW2 of the release button 27 is ON (S116).

  When the system control unit 20 determines that SW2 is ON (Yes in S116), the system control unit 20 performs imaging (S117). When the system control unit 20 determines that SW2 is not ON (No in S116), the flow returns to S103.

  When there is a restriction on the focus detection target position P that can be selected by the image display unit 46 because there is a restriction on the correction movement amount of the camera shake correction lens unit 12, as shown by a circle D in FIG. A selectable range centered on the position of the focus detection pixel 31 may be displayed.

  According to the present embodiment, focus detection can be performed in a range exceeding the position of the focus detection pixel of the image sensor 30 by moving the correction lens before and after focus detection during live view.

  The configuration of the camera of the second embodiment is the same as that of the first embodiment. In the present embodiment, when the focus detection target position P desired by the photographer and the position of the focus detection pixel 31 are shifted in the live view mode, the image sensor 30 is moved by the amount of deviation. In the present embodiment, the influence of blur due to the movement of the image sensor 30 is reduced or eliminated by shifting the cutout range of the video in the image sensor 30.

  FIG. 6 is a flowchart for explaining the operation from when the system control unit 20 enters the live view mode to when shooting is performed. In FIG. 6, “S” stands for a step. The same steps as those in FIG. 3 are denoted by the same reference numerals.

  After performing S101 to S104 as in FIG. 3, the system control unit 20 moves the image sensor 30 by the amount of deviation calculated in S104 and also the image sensor 30 as shown in FIG. 4B. The image cutout range from is moved (S120). As a result, the focus detection target position P overlaps the focus detection pixel 31.

  The system control unit 20 controls the moving amount of the image sensor 30 and the moving amount of the image cutout range to be the same amount at the same time. Accordingly, the system control unit 20 can reduce or eliminate the display change of the image display unit 46 due to the movement of the image sensor 30. In addition, the image pickup device 30 is configured to be sufficiently large with respect to the image pickup range, so that the image pickup range is sufficiently accommodated in the image pickup device even when moved. As a result, the focus detection pixels 31 on the image sensor substantially coincide with the image for focus detection.

  Next, S107 is performed. Next, the system control unit 20 moves the image sensor 30 to the original position, and simultaneously moves the cutout range of the image from the image sensor 30 to the original position (S121). Also at this time, the system control unit 20 is controlled so that the moving amount of the image sensor 30 and the moving amount of the image clipping range are the same at the same time, and the display change of the image display unit 46 due to the movement of the image sensor 30 is controlled. Is reduced or eliminated. As a result, the focus detection target position P and the focus detection pixel 31 return to the state before the image sensor 30 is driven before the focus adjustment after focus detection.

  After S121, S110, S111, and S117 are performed. When S103 is No, S112 to S116 are performed.

  According to the present embodiment, the focus detection can be performed in a wider range than the position of the focus detection pixel on the existing imaging surface by correcting and moving the image sensor 30 before and after focus detection during live view shooting. .

  The configuration of the camera of the third embodiment is the same as that of the first embodiment. In this embodiment, when the focus detection target position P desired by the photographer and the position of the focus detection pixel 31 are deviated at the time of moving image shooting, the image sensor 30 is moved by the shift amount, and the photographer desires Focus detection is performed at the focus detection target position. Further, in this embodiment, the influence of blur due to the movement of the image sensor 30 is reduced or eliminated by moving the image cutout range in the image sensor.

  FIG. 7 is a flowchart for explaining the operation of the system control unit 20 from the start of moving image shooting by the operation of the moving image recording button 6 to the end of moving image shooting. In FIG. 7, “S” stands for a step. The same steps as those in FIG. 6 are denoted by the same reference numerals.

  When the moving image shooting starts (S130), the system control unit 20 uses the output of the image processing unit 42 and the output of the audio processing unit 43 to start recording a moving image and audio (S131). After S131, S103 to S110 are performed as in FIG.

  After S110, the system control unit 20 determines whether the moving image recording is finished (S132). If the system control unit 20 determines that the moving image recording has been completed (Yes in S132), it ends the recording of the moving image and the sound (S133), and ends the moving image recording (S134).

  On the other hand, in the case of No in S103, the system control unit 20 automatically selects the focus detection pixel 31 for predicting the position of the main subject and tracking the main subject (S135). After S135, S114 and S115 are performed, and after S115, the flow proceeds to S132.

  According to the present embodiment, the focus detection can be performed in a wider range than the focus detection pixels on the existing imaging surface by moving the image sensor 30 before and after focus detection during moving image shooting.

  Further, when the focus detection target position P is not input, it is not always necessary to automatically select a focus detection pixel or select a focus detection pixel for subject tracking.

  The focus detection method or focus adjustment method shown in FIGS. 3, 6, and 7 can be realized by a program as a method performed by the processor.

  The imaging device can be applied to imaging a subject.

12 image stabilization lens unit 20 system control unit 29 image sensor drive unit 30 image sensor 31 focus detection pixel 35 image sensor focus detection unit 46 image display unit

Claims (7)

An image pickup device having an image pickup pixel that photoelectrically converts an optical image and a focus detection pixel that performs phase difference focus detection;
An input unit for inputting a target position for focus detection;
An image sensor driving unit for driving the image sensor in a direction perpendicular to the optical axis;
A control unit that controls driving of the image sensor by the image sensor driving unit so that the target position overlaps the focus detection pixel;
A focus detection unit that performs focus detection of the target position by the focus detection pixel after the target position overlaps the focus detection pixel;
An imaging device comprising:   The control unit is configured to return the target position and the focus detection pixel to a state before the image sensor is driven before focus adjustment after focus detection by the focus detection unit. The image pickup apparatus according to claim 1, wherein the driving of the image pickup element is controlled. An image display unit that displays an optical image formed by the photographic lens;
The control unit is configured to change the image cutout range of the image pickup device and reduce the display change of the image display unit due to the drive of the image pickup device while the image pickup device drive unit drives the image pickup device. The imaging apparatus according to claim 1 or 2, wherein An image pickup device having an image pickup pixel that photoelectrically converts an optical image and a focus detection pixel that performs phase difference focus detection;
An input unit for inputting a target position for focus detection;
An image sensor driving unit for driving the image sensor in a direction perpendicular to the optical axis;
A control unit that controls driving of the optical image stabilization lens so that the target position overlaps the focus detection pixel;
A focus detection unit that performs focus detection of the target position by the focus detection pixel after the target position overlaps the focus detection pixel;
An imaging device comprising:   The control unit is configured so that the target position and the focus detection pixel return to a state before the optical image stabilization lens is driven before focus adjustment after focus detection by the focus detection unit. The imaging apparatus according to claim 4, wherein the driving of the optical camera shake correction lens is controlled. An image display unit that displays an optical image formed by the photographic lens;
The imaging apparatus according to claim 4, wherein the control unit fixes display contents of the image display unit while driving the optical camera shake correction lens.   The control unit selects one of a plurality of focus detection pixels closest to the target position as the focus detection pixel with which the target position overlaps. The imaging device according to item.