JP2011090048A - Automatic focus regulator for camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic focus regulator for a camera which is high in accuracy in the prediction of a moving object even if a moving amount of the moving object is abruptly changed immediately before photographing. <P>SOLUTION: An AF/AECPU calculates a predicted target drive position based on a target drive position obtained in the past excepting the obtained last target drive position when not receiving an indication of exposure. That is, the target drive position in time (t)=T0+T1 is predicted based on the target drive position obtained in a period (T0) before a computation time point not using the target drive position obtained in the computation time point in moving object prediction computation (g<SB>4</SB>). On the other hand, the target drive positions in time t= T0+T2 and t=T0+T3 are predicted based on the target drive positions obtained in the past including the target drive position obtained in the computation time point in moving object prediction computation (k<SB>1</SB>) when receiving the indication of exposure. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an automatic focusing apparatus for a camera.

  Many techniques relating to so-called moving object prediction for focusing on a moving object in a camera have been conventionally devised. The technique related to moving object prediction is a technique for detecting the focus of a moving subject, predicting the future image plane position of the moving subject, and driving the lens so as to focus on the predicted image plane position. For example, Patent Document 1 discloses a technique for calculating the image plane position of a future subject based on the current and past defocus amounts while continuously detecting the defocus amount that is a focus shift. . Furthermore, a technology of an automatic focus adjustment device that performs drive control of the focus adjustment lens so as to focus on the calculated image plane position of a future subject is disclosed. In the technique disclosed in Patent Document 1, in order to improve the accuracy of moving object prediction, in the lens driving control executed simultaneously with the moving object prediction calculation at the time of detecting the latest defocus amount, the latest detected defocus amount is The defocus amount detected before the previous time is used instead of the moving object prediction calculation.

JP-A-5-2127

  However, in the technique disclosed in Patent Document 1, since the moving object prediction calculation is performed using the defocus amount detected before the previous time, the moving object prediction is performed when the moving amount of the subject moving immediately before the exposure changes abruptly. Accuracy may be reduced. As a result, there is a problem that an error between the result obtained by the moving object prediction calculation and the actual subject motion becomes large, and the focus adjustment accuracy deteriorates.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an automatic focusing apparatus for a camera having high moving object prediction accuracy even when the amount of movement of a subject moving immediately before exposure changes rapidly.

  In order to achieve the above object, one aspect of an automatic focusing apparatus for a camera according to the present invention includes a focus detection unit that detects a defocus amount that is a focus state of a focus lens, and the defocus amount detected by the focus detection unit. And a position of the focus lens calculated based on the position of the focus lens detected by the position detection unit at the time when the focus detection unit detects the defocus amount. And a target drive position acquisition unit that acquires the defocus amount, and a target drive position acquisition unit that acquires the defocus amount based on a plurality of target drive positions acquired in time series by the target drive position acquisition unit. A moving body predicting means for calculating a predicted target drive position at which the position of the focus lens is an in-focus position; and the focus to the predicted target drive position. Lens moving instruction means for instructing movement of the lens, and the moving object prediction means at the time of the moving object prediction operation for repeatedly calculating the predicted target drive position, if the exposure instruction is not received, The first predicted target drive position is calculated based on the target drive position obtained after the start of the moving body predicting operation except for the target drive position, and if the exposure instruction is received, the latest obtained A second predicted target drive position is calculated based on the target drive position obtained after the start of the moving object prediction operation including the target drive position.

  According to the present invention, it is possible to provide an automatic focusing apparatus for a camera having high moving object prediction accuracy even when the amount of movement of a subject moving immediately before exposure changes rapidly.

Schematic of an example of the single-lens reflex camera as a camera carrying the camera automatic focus adjustment apparatus which concerns on each embodiment of this invention. Schematic which shows an example of the focus detection area displayed in a finder. (A) is a figure which shows an example of a structure of a focus detection optical system concerning the camera in each embodiment, (B) is a front view of an example of a field mask, (C) is an example of a separator aperture mask. It is a front view, (D) is a front view of an example of a separator lens, (E) is a front view of an example of an AF sensor, (F) is a hypothetical | virtual material which combined each lens group in an interchangeable lens part. It is a front view of an example of the taking lens which is a lens. FIG. 2 is a block diagram illustrating an example of an electrical configuration of the camera illustrated in FIG. 1. The flowchart which shows an example of the moving body prediction process at the time of not receiving the instruction | indication of exposure of the camera in each embodiment. The figure which shows an example of the operation | movement sequence of a moving body prediction process of the camera carrying the camera automatic focus adjustment apparatus which concerns on the 1st Embodiment of this invention. The figure explaining an example of the moving body prediction calculation of the camera in each embodiment. 5 is a flowchart illustrating an example of a moving object prediction process when receiving an exposure instruction of the camera according to the first embodiment. The flowchart which shows an example of the moving body prediction process at the time of receiving the instruction | indication of exposure of the camera which mounts the automatic focus adjustment apparatus for cameras which concerns on the 2nd Embodiment of this invention. The figure which shows an example of the operation | movement sequence of the moving body prediction process of the camera in 2nd Embodiment.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. First, FIG. 1 shows an outline of an example of a single-lens reflex camera as a camera according to each embodiment of the present invention. The configuration shown in FIG. 1 and the following description of the present embodiment assume a digital still camera. However, each embodiment of the present invention is of course applicable to a silver salt still camera as well. It is. This camera includes a camera body 100 and an interchangeable lens unit 101 that can be attached to and detached from the camera body 100.

  The interchangeable lens unit 101 includes a focus adjustment lens 102 and a zoom lens 103. The focus adjustment lens 102 is driven in the optical axis direction to adjust the focus state of the interchangeable lens unit 101. The zoom lens 103 is driven in the optical axis direction to change the focal length of the interchangeable lens unit 101.

  On the other hand, the camera body 100 includes a main mirror 104, a sub mirror 105, a focus detection optical system 106, a focus detection sensor (hereinafter referred to as AF sensor) 107, a focal plane shutter 108, an image sensor 109, a screen mat 110, and a viewfinder optical system 111. And an eyepiece 112.

  The main mirror 104 is composed of a half mirror, which partially transmits and partially reflects the light flux from the subject. Further, the main mirror 104 is configured to be rotatable in a direction indicated by an arrow in the drawing so that all light beams are incident on an imaging surface formed by the imaging element 109 during exposure.

  Except at the time of exposure, the light beam from the subject transmitted through the main mirror 104 is reflected by the sub mirror 105 and guided to the focus detection optical system 106. The focus detection optical system 106 includes a lens for focus detection and the like, and guides the light beam reflected by the sub mirror 105 to the AF sensor 107. The detailed configuration of the focus detection optical system 106 will be described in detail later.

  The AF sensor 107 is, for example, a sensor composed of a photodiode array. The AF sensor 107 is configured to be able to detect a plurality of focus points. That is, the AF sensor 107 has a plurality of photodiode arrays corresponding to a plurality of focus detection areas. The detailed configuration of the AF sensor 107 will also be described in detail later.

  As described above, at the time of exposure, the main mirror 104 is retracted from the optical axis of the interchangeable lens unit 101, so that the light flux from the subject is incident in the imaging surface direction. At this time, the focal plane shutter 108 is driven and controlled to give an appropriate amount of light to the imaging surface. In the case of a digital still camera, a CCD, a CMOS sensor, or the like is used for the image pickup element 109 that forms the image pickup surface. In the case where the camera is a silver salt camera, a silver salt film is used instead of the image sensor 109. When the above-described focal plane shutter 108 is opened, the light flux from the subject enters the imaging surface formed by the imaging element 109.

  Further, at times other than the exposure time, the light beam from the subject reflected by the main mirror 104 is incident in the finder direction, and an image is formed by the screen mat 110. This image enters the eyepiece 112 through the finder optical system 111. The photographer can know the photographing range, the focused state of the subject, and the like by looking into the eyepiece 112.

  FIG. 2 is a schematic diagram of a focus detection area displayed in the viewfinder. When the photographer looks into the eyepiece 112, focus detection area marks 113 corresponding to the plurality of focus detection areas of the AF sensor 107 are displayed in the viewfinder. Note that the example of FIG. 2 shows an example of multi-AF having 11 distance measuring areas.

  Next, the configurations of the focus detection optical system 106 and the AF sensor 107 will be described in detail with reference to FIGS. As shown in FIG. 3A, the focus detection optical system 106 includes a field mask 120, a condenser lens 121, a total reflection mirror 122, an infrared cut filter 123, a separator diaphragm mask 124, and a separator lens 125. In the drawing, each lens group in the interchangeable lens unit 101, for example, a virtual lens obtained by synthesizing the focus adjustment lens 102 and the zoom lens 103 is illustrated as a photographing lens 126.

  The field mask 120 narrows down the light beam obtained through the sub mirror 105. In order to transmit the light fluxes (dotted lines in the drawing) of the plurality of focus detection areas guided from the sub mirror 105, the field mask 120 has an opening 127 as shown in the front view of FIG.

  The condenser lens 121 is for condensing the light that has passed through the field mask 120. The condenser lens 121 is arranged corresponding to the position of the opening 127 of the field mask 120.

  The total reflection mirror 122 reflects the light beam and guides it in the direction of the separator diaphragm mask 124 via the infrared cut filter 123.

  The infrared cut filter 123 is a filter for cutting an infrared light component harmful to focus detection.

  The separator diaphragm mask 124 is for narrowing the incident light flux. This separator diaphragm mask 124 has four openings 124a, 124b, 124c, as shown in the front view of FIG. 3C, in order to divide the light beam obtained through the condenser lens 121 into four light beams. 124d.

  The separator lens 125 re-images the light beam obtained through the separator diaphragm mask 124 on the AF sensor 107. The separator lens 125 includes four separator lenses 125a, 125b, 125c, and 125d as shown in the front view of FIG.

  The AF sensor 107 described above has four photodiode array sections 128a, 128b, and 128c as shown in the front view of FIG. 3E, which is a photoelectric conversion element array that obtains a light intensity signal corresponding to the light intensity distribution of the received light flux. , 128d. Among these, the photodiode array units 128a and 128b are arranged in a direction corresponding to the horizontal direction of the shooting screen, and the other two photodiode array units 128c and 128d are arranged in a direction corresponding to the vertical direction of the shooting screen. It is arranged and has a so-called cross sensor type configuration capable of detecting a subject pattern in the horizontal and vertical directions within one distance measuring area.

  In the focus detection optical system 106 configured in this way, focus detection that passes through different areas 126a and 126b and areas 126c and 126d on the exit pupil plane of the photographing lens 126 as shown in the front view of FIG. Light beams are received by the photodiode array units 128a, 128b and 128c, 128d, respectively, and converted into electrical signals indicating the light intensity distribution pattern of the image. Using this light intensity signal, focus detection is performed by a TTL phase difference method which is one method of focus detection.

  Note that reference numeral 129 in FIG. 3A indicates a primary imaging plane at a distance equivalent to the imaging element 109 constituting the imaging plane.

  The electrical configuration of the camera as described above will be described with reference to FIG. First, a configuration related to the interchangeable lens unit 101 will be described. A zoom driving rotary ring 130 and a manual focus (MF) rotary ring 131 that are ring-shaped so as to surround the periphery of the interchangeable lens unit 101 are disposed. The photographer can change the focal length of the interchangeable lens unit 101 by driving the zoom lens 103 in the optical axis direction by rotating the zoom driving rotary ring 130 about the optical axis of the interchangeable lens unit 101. .

  When the MF rotating ring 131 is rotated about the optical axis of the interchangeable lens unit 101, the focus adjustment lens 102 is driven in the optical axis direction in conjunction therewith. Thereby, the focus of the interchangeable lens part 101 can be adjusted manually. The MF rotating ring 131 is used when the photographer selects a manual focus mode by operating a changeover switch (not shown) that switches between an autofocus mode and a manual focus mode.

  The interior of the interchangeable lens unit 101 includes a lens CPU (hereinafter referred to as lens drive control, aperture drive control, communication control, etc.) for controlling the focus adjustment lens 102, the zoom lens 103, the diaphragm 132, and the interchangeable lens unit 101. (Referred to as LCPU) 133. The LCPU 133 is connected to a zoom position detection circuit 134, a diaphragm drive circuit 135, a lens drive circuit 136, a lens position detection circuit 137, and a communication circuit 138.

  The position of the zoom lens 103 driven by the zoom driving rotary ring 130 is detected by a zoom position detection circuit 134. The LCPU 133 obtains focal length information of the interchangeable lens unit 101 based on the position of the zoom lens 103 detected by the zoom position detection circuit 134.

  The aperture 132 includes an opening for adjusting the amount of light incident in the direction of the camera body 100. The LCPU 133 changes the size of the opening of the diaphragm 132 by controlling the diaphragm driving circuit 135 so that an appropriate amount of light enters the camera body 100 direction.

  In the autofocus mode, the LCPU 133 calculates the drive amount of the focus adjustment lens 102 and controls the lens drive circuit 136 to drive the focus adjustment lens 102. The position of the focus adjustment lens 102 driven by the lens driving circuit 136 is detected by a lens position detection circuit 137. The lens position detection circuit 137 includes, for example, a photo interrupter (PI) circuit that detects the rotation amount of the drive motor included in the lens drive circuit 136 by converting it into the number of pulses. In this photo interrupter circuit, the absolute position from the focus adjustment lens 102 is represented by the number of pulses from a certain reference position. The LCPU 133 obtains the focus state information of the interchangeable lens unit 101 based on the lens position detected by the lens position detection circuit 137. The LCPU 133 calculates the number of pulses necessary for focusing based on this focus state information and information obtained through communication with the AF / AECPU described later.

  Further, the LCPU 133 communicates information such as the aperture driving amount and the defocus amount of the interchangeable lens unit 101 with the CPU and AF / AECPU of the camera body, which will be described in detail later, via the communication circuit 138. For this reason, the communication connection terminal of the communication circuit 138 is provided outside the interchangeable lens unit 101.

  Next, a configuration related to the camera body 100 will be described. The interior of the camera body 100 is configured to include a body CPU 139 that controls the entire camera. The main body CPU 139 temporarily stores a communication line 140 for communicating with the LCPU 133 via the communication circuit 138, a flash ROM (FROM) 141 in which programs of the main body CPU 139 are stored, and various information of the main body CPU 139. A RAM 142, an image sensor control circuit 143 that controls the image sensor 109 to obtain image data, a strobe control circuit 144 that controls a strobe (not shown), a mirror control circuit 145 that controls up / down of the main mirror 104, and a focal plane shutter 108. A shutter control circuit 146 for controlling, an image processing circuit 147 for image processing of image data obtained by the image sensor control circuit 143, a display circuit 148 for displaying captured images and various types of shooting information on a display unit (not shown), a photographer Various operations operated by Operation switch detecting circuit 149 that the switch is connected, the power supply circuit 150 for supplying power to the camera, and AF / AECPU151 is connected.

  Here, the operation switch detection circuit 149 includes a changeover switch (not shown) that switches the shooting mode of the camera, a release switch that operates by operating a release button, and the like. The release switch in the present embodiment is a general two-stage switch. That is, when the release button is half-pressed, the first release switch 152 (hereinafter referred to as 1R switch) is turned on to perform focus detection and photometry, and the focus adjustment lens 102 is driven to be in focus. Further, when the release button is fully pressed, the second release switch 153 (hereinafter referred to as a 2R switch) is turned on, and the main mirror 104 and the focal plane shutter 108 are driven to perform exposure.

  Further, the power supply circuit 150 performs smoothing or boosting of the voltage of the battery 154 loaded. The AF / AECPU 151 performs automatic focus adjustment (AF) control and photometry (AE) control of the camera. The AF / AECPU 151 performs a moving object prediction calculation of the subject in the continuous AF mode. The AF / AECPU 151 includes a communication line 155 for communicating with the AF / AECPU 151 via the communication circuit 138 of the interchangeable lens unit 101, a communication line 156 for communicating with the AF / AECPU 151 and the main body CPU 139, and AF. A flash ROM (FROM) 157 storing a program of the / AECPU 151, a RAM 158 for temporarily storing various information of the AF / AECPU 151, a photometry circuit 159, a focus detection circuit 160, and an auxiliary light circuit 161 are connected. In the autofocus mode, the AF / AECPU 151 acquires the number of pulses necessary for focusing, calculated by the LCPU 133, via the communication line 155. Further, in the autofocus mode, the AF / AECPU 151 gives an instruction for driving the focus adjustment lens 102 to the LCPU 133 via the communication line 155.

  Here, the photometric circuit 159 is a circuit for obtaining subject luminance information by controlling a photometric element (not shown) that measures the subject luminance. The focus detection circuit 160 is a circuit for performing focus detection calculation based on information obtained by controlling the AF sensor 107 and obtaining focus detection information. Further, the auxiliary light circuit 161 is a circuit for projecting light onto a subject by a light emitting element such as an LED when performing focus detection again when the subject has low brightness and focus detection by the focus detection circuit 160 is impossible. It is.

  In the single-lens reflex camera equipped with the automatic focus adjustment apparatus according to the present embodiment, it is possible to switch between the single AF mode and the continuous AF mode by an AF mode switching switch (not shown) included in the operation switch detection circuit 149. It has become. Here, the single AF mode is an AF mode in which the focus is locked once an in-focus state is detected, and the continuous AF mode is an object that moves by continuously performing focus detection and lens driving. This is an AF mode for performing so-called moving object prediction AF.

  As described above, for example, the AF sensor 107, the AF / AECPU 151, and the focus detection circuit 160 function as a focus detection unit as a whole, and for example, the AF / AECPU 151 and the communication line 155 function as a target drive position acquisition unit and a lens drive instruction unit as a whole. For example, the AF / AECPU 151 functions as a moving body prediction unit, the AF sensor 107 functions as a focus detection sensor, and the mirror control circuit 145 functions as an optical path switching unit, for example.

  Hereinafter, the operation in the continuous AF mode of the automatic focusing apparatus for a camera according to the present embodiment will be described with reference to the drawings. First, FIG. 5 shows an example of a flowchart of the operation when the 1R switch 152 is in the ON state in this embodiment. Note that this operation includes a parallel operation, and in FIG. 5, the branch point immediately before the parallel operation is indicated by a black circle. Further, description will be made with reference to FIG. 6A showing an operation sequence when the 1R switch 152 is in the ON state.

  First, when it is detected that the 1R switch 152 is turned on, in step S101, the main body CPU 139 starts an internal timer (not shown) of the camera main body 100 for measuring a focus detection time interval and the like. As this internal timer, an internal timer provided in the AF / AECPU 151 may be used. In step S102, the AF / AECPU 151 reads the timer count value and stores it in the RAM 158.

In step S103, the AF / AECPU 151 causes the AF sensor 107 to start the accumulation operation via the focus detection circuit 160. When the accumulation level reaches a predetermined level, the AF sensor 107 ends the accumulation operation (FIG. 6A). ) (A ₁ )). When the accumulation operation of the AF sensor 107 is completed, in step S104, the AF / AECPU 151 converts the photoelectric conversion signal (hereinafter referred to as sensor data) detected in the accumulation operation into a digital signal by the A / D conversion circuit in the focus detection circuit 160. Convert to and read. The read digital sensor data is stored in the RAM 158. Further, correction for canceling the fixed pattern noise of the read sensor data, an offset component due to dark current, a predetermined filter calculation, and the like are performed (FIG. 6 (A) (b ₁ )).

  In step S105, the AF / AECPU 151 performs well-known correlation calculation, interpolation calculation, and the like using the sensor data subjected to correction, calculation, etc., and obtains two image interval values in each of the 11 focus detection areas shown in FIG. . The reliability of the obtained two-image interval value is determined by a predetermined method. As a result of the determination, a defocus amount that is a focus shift is calculated from the two image interval values of the focus detection area determined to be reliable. If the focus detection area selection mode of the camera is the spot AF mode, the defocus amount of the designated focus detection area is selected. If the focus detection area selection mode of the camera is the multi-AF mode, the defocus amount of one focus detection area is selected by a predetermined selection method such as closest detection.

  In step S106, the AF / AECPU 151 determines the reliability of the defocus amount. If it is determined in step S106 that the defocus amount reliability of the designated focus detection area in the spot AF mode or the defocus amount reliability of all the focus detection areas in the multi AF mode is not reliable, the step In S107, the LCPU 133 performs a predetermined process such as instructing the lens scan to be executed, or the main body CPU 139 instructs the display circuit 148 to display that focus detection is impossible, and the process proceeds to Step S102.

  When it is determined in step S106 that the defocus amount of the designated focus detection area in the spot AF mode is reliable or the defocus amount of any focus detection area in the multi AF mode is reliable. In step S108, the AF / AECPU 151 associates the obtained defocus amount with the timer count value read in step S102, and stores it in the RAM 158 as defocus amount time-series data.

In step S109, the AF / AECPU 151 outputs the obtained defocus amount to the LCPU 133 via the communication line 155 and the communication circuit 138. LCPU133 includes a defocus amount input from the AF / AECPU151, based on the current position of the focusing lens 102 obtained by the lens position detection circuit 137 determines the target number of pulses (Fig. 6 (A) _{(c 1} )). Under the instruction of the AF / AECPU 151, the LCPU 133 sets the obtained target pulse number as the drive pulse number, controls the lens drive circuit 136 based on the target pulse number, and starts lens driving (FIG. 6A (d ₁ )). Further, the LCPU 133 outputs the obtained target pulse number to the AF / AECPU 151 via the communication line 155 and the communication circuit 138. In step S110, the AF / AECPU 151 associates the target pulse number input from the LCPU 133 with the timer count value read in step S102, and stores it in the RAM 158 as target pulse number time-series data.

In step S111, the AF / AECPU 151 reads the timer count value as in step S102, and stores it in the RAM 158. In step S112, the AF / AECPU 151 instructs the AF sensor 107 to start the accumulation operation as in step S103. Further, when the accumulation level of the sensor data reaches a predetermined level, the AF sensor 107 is instructed to end the accumulation operation (FIG. 6 (A) (e ₁ )). When the accumulation operation of the AF sensor 107 is completed, in step S113, the AF / AECPU 151 reads the accumulated sensor data and stores it in the RAM 158 as in step S104. Further, the read sensor data is corrected (FIG. 6A, (f ₁ )), and the process proceeds to step S116.

  In parallel with steps S112 and S113, main body CPU 139 determines the state of 2R switch 153 in step S114. If it is determined in step S114 that the 2R switch 153 is on, the 2R sequence is started. On the other hand, if the 2R switch 153 is in the OFF state in the determination in step S114, the main body CPU 139 determines the state of the 1R switch 152 in step S115. If it is determined in step S115 that the 1R switch 152 is not in the ON state, the process proceeds to a shooting standby sequence and waits for the next camera operation by the user. On the other hand, if it is determined in step S115 that the 1R switch 152 is on, the process proceeds to step S116.

  In step S116, the AF / AECPU 151 calculates the defocus amount of each focus detection area, as in step S105. In step S117, the AF / AECPU 151 determines the reliability of the defocus amount as in step S106. If it is determined in step S117 that the defocus amount is not reliable, the process proceeds to step S107. If it is determined in step S117 that the defocus amount is reliable, the AF / AECPU 151 in step S118 corresponds to the timer count value read in step S111 in the same manner as in step S108. The defocus amount time series data is stored in the RAM 158.

  In step S <b> 119, the AF / AECPU 151 performs moving body prediction calculation using the target pulse number time-series data stored in the RAM 158. A predicted pulse number P1, which is a predicted value of the target pulse number, is calculated by moving object prediction calculation.

Here, an example of the moving object prediction calculation will be described with reference to FIGS. 6 (A) and 7 (A). Here, it is assumed that the moving object prediction calculation of interest is “(g ₄ ) calculation” represented by shading in FIG. FIG. 7A shows the relationship between the timer count value (t) and the target pulse number (P). Note that the time (t) when the 1R switch 152 is turned on and the first accumulation is started is t = 0. A black dot indicates the target pulse number obtained up to the point of interest. In the example shown in FIGS. 6A and 7A, the target pulse number obtained up to the point of “(g ₄ ) calculation” is “(c ₁ ) calculation” or “(g ₁ ) calculation”. “(G ₂ ) operation” and “(g ₃ ) operation” are the four points obtained. Here, it should be noted that all the timer count values (t) are obtained at the start of sensor data accumulation by the AF sensor 107 immediately before the calculation is performed. That is, the target pulse number obtained by the “(g ₃ ) calculation” is stored in the RAM 158 in association with the timer count value (t) acquired at the start of “(e ₃ ) accumulation”. From these values, a prediction straight line L (P = at + b) is obtained by, for example, the least square method. Elapsed time from t = 0 until the start of accumulation of sensor data ((e ₃ ) accumulation) performed to obtain the latest target pulse number obtained up to the point of interest ((g ₄ ) calculation) Let time be T0. The next drive pulse number is updated from the start of accumulation of sensor data ((e ₃ ) accumulation) performed to obtain the latest target pulse number obtained up to the point of interest ((g ₄ ) calculation) The time until the set time ((g ₅ ) calculation) is T1. The sum of T0 and T1 is substituted into the formula (P = at + b) of the prediction line L to obtain the predicted pulse number P1 that is the predicted value of the target pulse number at the time t = T0 + T1 (FIG. 7A). In addition, although it demonstrated using the prediction straight line L by a linear expression here, it uses the prediction curve by a quadratic expression or a higher order expression, for example according to photography conditions, such as a subject speed and the change tendency of time series data. Also good.

Returning to FIG. In step S120, the AF / AECPU 151 outputs the defocus amount obtained in step S116 to the LCPU 133 via the communication circuit 138. The LCPU 133 obtains the target pulse number in the same manner as in step S109 based on the defocus amount input from the AF / AECPU 151 and the current position of the focus adjustment lens 102 obtained by the lens position detection circuit 137 (FIG. 6 ( A) (g ₁ )). The LCPU 133 outputs the obtained target pulse number to the AF / AECPU 151. On the other hand, the AF / AECPU 151 outputs the predicted pulse number P1 obtained in step S119 and the lens driving instruction to the LCPU 133. The LCPU 133 sets the predicted pulse number P1 input from the AF / AECPU 151 as the drive pulse number, and continues lens driving based on the number (FIG. 6 (A) (h ₁ )). In FIG. 6A (g ₁ ), the number of time-series data for obtaining the predicted pulse number P1 is insufficient, but if time-series data before t = 0 is stored, this time-series data is stored. When calculation is performed using data, and time-series data does not exist or the number is insufficient, another calculation method is used.

  In step S121, the AF / AECPU 151 associates the target pulse number input from the LCPU 133 in step S120 with the timer count value read in S111, stores the target pulse number time series data in the RAM 158, and proceeds to step S111.

As described above, the steps S111 to S121 are repeated while the 2R switch is off and the 1R switch is on. This operation corresponds to the repetition of (e _n ) to (h _n ) in FIG.

  Next, in the present embodiment, an operation when the 2R switch 152 is in the on state will be described with reference to an example of a flowchart shown in FIG. 8 and an operation sequence shown in FIGS. 6B and 7C. Note that the flowchart of FIG. 8 includes a parallel operation. In the figure, the branch point immediately before the parallel operation is indicated by a black circle.

In step S131, the LCPU 133 continues driving the focus adjustment lens 102 based on the predicted number of pulses P1 input from the AF / AECPU 151 from step S120 (FIG. 6B (h _n )).

The AF / AECPU 151 executes Steps S132 to S140 in parallel with Step S131. Steps S132 to S136 are the remaining processes of the 1R sequence, and correspond to steps S112 to S118, respectively. In step S132, the AF / AECPU 151 instructs the AF sensor 107 to start the accumulation operation, similarly to step S112. Further, when the accumulation level of the sensor data reaches a predetermined level, the AF sensor 107 is instructed to end the accumulation operation (FIG. 6B (i ₁ )). When the accumulation operation of the AF sensor 107 is completed, in step S133, the AF / AECPU 151 reads the accumulated sensor data and stores it in the RAM 158 as in step S113. Further, correction of the read sensor data is performed (FIG. 6B (j ₁ )). In step S134, the AF / AECPU 151 calculates the defocus amount of each focus detection area, as in step S116. In step S135, the AF / AECPU 151 determines the reliability of the defocus amount as in step S116. If it is determined in step S135 that the defocus amount is not reliable, the process proceeds to step S140. If it is determined in step S135 that the defocus amount is reliable, in step S136, the AF / AECPU 151 determines the obtained defocus amount and the timer count value read in step S111 in the same manner as in step S118. The association and defocus amount time series data is stored in the RAM 158.

In step S137, the AF / AECPU 151 outputs the defocus amount obtained in step S134 to the LCPU 133 via the communication circuit 138. In step S138, the LCPU 133 obtains the target pulse number based on the defocus amount input from the AF / AECPU 151 and the current position of the focus adjustment lens 102 obtained by the lens position detection circuit 137, as in step S109. (FIG. 6 (B) (k ₁ )). In step S139, the LCPU 133 outputs the target pulse number obtained in step S138 to the AF / AECPU 151. The AF / AECPU 151 associates this latest target pulse number with the timer count value read in S111 and stores it in the RAM 158 as target pulse number time-series data.

In step S140, the AF / AECPU 151 performs moving object prediction using the target pulse number time-series data including the latest target pulse number and stored in the RAM 158, and calculates the predicted pulse number (FIG. 6 (B) (k ₁ )). There are two predicted pulses to be calculated here. One is the predicted number of pulses at the start of exposure. The other is the predicted number of pulses at the time when the first target number of pulses is calculated after mirror down after completion of exposure.

An example of the calculation of the predicted number of pulses will be described with reference to FIGS. 6B and 7B. The moving object prediction calculation of interest here is “(k ₁ ) calculation” in FIG. FIG. 7B shows the relationship between the timer count value (t) and the target pulse number (P) as in FIG. 7A, and the time (t) at which the first accumulation is started is t = 0. . The target number of pulses obtained up to the point of interest and used for the moving object prediction calculation is indicated by black dots. Here, the target number of pulses obtained in the “(k ₁ ) calculation” is used for the moving object prediction calculation. From these values, a prediction straight line L (P = at + b) is obtained by, for example, the least square method. From t = 0 to the start point of accumulation of sensor data ((i ₁ ) accumulation) performed to obtain the latest target pulse number obtained up to the point of interest ((k ₁ ) calculation) Let elapsed time be T0. From the start time of sensor data accumulation ((i ₁ ) accumulation) performed to obtain the latest target pulse number obtained up to the point of interest ((k ₁ ) calculation) to the exposure start time The time is T2, and the time until the time ((v ₁ ) accumulation) at which the first target pulse number is calculated after mirror down after completion of exposure is T3. The sum of T0 and T2 is substituted into the formula (P = at + b) of the prediction line L, and a predicted pulse number P2 that is a predicted value of the target pulse number at the start of exposure is obtained. Also, the sum of T0 and T3 is substituted into the formula (P = at + b) of the prediction line L, and the prediction is a prediction value of the target pulse number at the time when the first target pulse number after mirror down after the exposure is calculated is calculated. The number of pulses P3 is obtained. In addition, although it demonstrated using the prediction straight line L by a linear expression here, it uses the prediction curve by a quadratic expression or a higher order expression, for example according to photography conditions, such as a subject speed and the change tendency of time series data. Also good.

Returning to FIG. In step S141, the AF / AECPU 151 calculates the aperture value based on the subject luminance information acquired by the photometry circuit 159. Then, the AF / AECPU 151 outputs the calculated aperture value and the predicted pulse number P2 obtained by the moving object prediction calculation in step S140 to the LCPU 133 via the communication circuit 138. The LCPU 133 sets the predicted pulse number P2 input from the AF / AECPU 151 as the drive pulse number, and controls the lens drive circuit 136 based on this to drive the focus adjustment lens 102 (FIG. 6B (l ₁ )). Further, the LCPU 133 performs the diaphragm drive control of the diaphragm 132 by the diaphragm drive circuit 135 based on the diaphragm value input from the AF / AECPU 151 (FIG. 6B (m ₁ )). In step S142, the AF / AECPU 151 counts the lens driving time (for example, the time until the bounce of the main mirror 104 and the sub mirror 105 stops after mirror-up driving) by an internal timer. After elapse of the lens driving time counted in step S142, in step S143, the LCPU 133 stops the lens driving when the lens driving for the predicted number of pulses P2 is completed. The AF / AECPU 151 counts the lens drive limit time. When the limit time elapses, the AF / AECPU 151 transmits a lens drive stop signal for stopping the drive of the focus adjustment lens 102 to the LCPU 133 via the communication circuit 138. The lens driving stop signal at this time functions as a lens driving time limiter for preventing the release time lag from becoming longer than necessary, and the lens driving for the predicted number of pulses P2 is intended to be ended before this. Yes. The LCPU 133 stops the driving of the focus adjustment lens 102 based on the lens driving stop signal input from the AF / AECPU 151 (FIG. 6B (n ₁ )).

In step S144, the main body CPU 139 instructs the mirror control circuit 145 to perform mirror-up drive control in parallel with steps S141 to S143. The mirror control circuit 145 performs mirror-up driving based on a command input from the main body CPU 139 (FIG. 6 (B) (o ₁ )).

In step S145, the AF / AECPU 151 performs a photometric calculation based on the subject luminance information acquired by the photometric circuit 159, and calculates a shutter speed. Then, the AF / AECPU 151 outputs the calculated shutter speed to the main body CPU 139. The main body CPU 139 operates the focal plane shutter 108 via the shutter control circuit 146 based on the shutter speed input from the AF / AECPU 151. The main body CPU 139 controls the image sensor 109 via the image sensor control circuit 143 to acquire image data of the subject image (FIG. 6B (p ₁ )). The main body CPU 139 outputs the acquired imaging data to the image processing circuit 147 and causes the image processing circuit 147 to execute predetermined image processing. The main body CPU 139 stores the image data processed by the image processing circuit 147 in an external storage means (not shown) such as the RAM 142 or Compact Flash (registered trademark). Further, the main body CPU 139 outputs the processed image by the display circuit 148 and displays it on a display unit (not shown) such as a TFT monitor.

  In step S146, the main body CPU 139 determines whether or not the shooting mode of the camera is the continuous shooting mode. If the result of this determination is that the shooting mode of the camera is continuous shooting mode, processing proceeds to step S147 and step S148. On the other hand, when the shooting mode of the camera is not the continuous shooting mode but the single shooting mode, the process proceeds to S165 and step S166.

In step S 147, the AF / AECPU 151 outputs an aperture opening signal to the LCPU 133 via the communication circuit 138. Based on the aperture opening signal input from the AF / AECPU 151, the LCPU 133 instructs the aperture driving circuit 135 to open the aperture 132 (FIG. 6B (q ₁ )). In parallel with step S147, in step S148, the main body CPU 139 instructs the mirror control circuit 145 to perform mirror down driving (FIG. 6B (r ₁ )). After the opening of the aperture 132 in step S147 and the mirror-down driving in step S148 are completed, in step 149, the AF / AECPU 151 reads the count value of the operating internal timer from the 1R sequence and stores it in the RAM 158.

In step S150, the AF / AECPU 151 causes the AF sensor 107 to start an accumulation operation as in step S132. Further, when the accumulation level of the sensor data reaches a predetermined level, the accumulation operation is terminated in the AF sensor 107 (FIG. 6B (s ₁ )).

After the accumulation operation of the AF sensor 107 is completed, in step S151, the AF / AECPU 151 outputs the predicted pulse number P3 obtained in step S140 and the lens driving instruction to the LCPU 133 via the communication circuit 138 in the same manner as in step S131. To do. The LCPU 133 sets the predicted pulse number P3 input from the AF / AECPU 151 as the drive pulse number, and controls the lens drive circuit 136 based on this to drive the focus adjustment lens 102 (FIG. 6B (t ₁ )).

The AF / AECPU 151 executes steps S152 to S159 in parallel with step S151. In step S152, the AF / AECPU 151 reads the accumulated sensor data and stores it in the RAM 158 as in step S133. Further, correction of the read sensor data is performed (FIG. 6B (u ₁ )). In step S153, the AF / AECPU 151 calculates the defocus amount of each focus detection area, as in step S134. In step S154, the AF / AECPU 151 determines the reliability of the defocus amount as in step S135. If it is determined in step S154 that the defocus amount is not reliable, the process proceeds to step S159.

  If it is determined in step S154 that the defocus amount is reliable, the AF / AECPU 151 in step S155 determines the obtained defocus amount and the timer count value read in step S149 in the same manner as in step S136. The association and defocus amount time series data is stored in the RAM 158.

In step S156, the AF / AECPU 151 outputs the defocus amount obtained in step S153 to the LCPU 133 via the communication circuit 138, similarly to step S137. In step S157, the LCPU 133 obtains the target pulse number based on the defocus amount input from the AF / AECPU 151 and the current position of the focus adjustment lens 102 obtained by the lens position detection circuit 137, as in step S138. (FIG. 6 (B) (v ₁ )).

  In step S158, the LCPU 133 outputs the obtained target pulse number to the AF / AECPU 151 in the same manner as in step S139. The AF / AECPU 151 associates this latest target pulse number with the timer count value read in S149 and stores it in the RAM 158 as target pulse number time-series data.

In step S159, the AF / AECPU 151 performs a moving object prediction calculation using the target pulse number time-series data stored in the RAM 158 (FIG. 6B (v ₁ )). The moving object prediction calculation performed here is the same as the moving object prediction calculation (FIG. 6B (k ₁ )) performed in step S140. That is, a prediction pulse P2 that is a predicted value of the target pulse number at the next exposure start time and a prediction value that is a predicted value of the target pulse number at the time when the first target pulse number after mirror down after the exposure is calculated is calculated. The pulse P3 is calculated.

In step S160, the AF / AECPU 151 calculates the aperture value based on the subject luminance information acquired by the photometry circuit 159, as in step S141. Then, the AF / AECPU 151 outputs the calculated aperture value, the predicted pulse number P2 obtained by the moving object prediction calculation in step S157, and the lens driving instruction to the LCPU 133 via the communication circuit 138. The LCPU 133 sets the predicted number of pulses P2 input from the AF / AECPU 151 as the number of driving pulses, and controls the lens driving circuit 136 based on this to drive the focus adjustment lens 102 (FIG. 6B (l ₂ )). Further, the LCPU 133 performs the diaphragm drive control of the diaphragm 132 by the diaphragm drive circuit 135 based on the diaphragm value input from the AF / AECPU 151 (FIG. 6B (m ₂ )). In step S161, the AF / AECPU 151 counts the lens driving time (for example, the time until the bounce of the main mirror 104 and the sub mirror 105 stops after the mirror-up driving) by the internal timer. After the elapse of the lens driving time counted in step S161, in step S162, the LCPU 133 stops the lens driving when the lens driving for the predicted number of pulses P2 is completed. The AF / AECPU 151 transmits a lens drive stop signal for stopping the drive of the focus adjustment lens 102 to the LCPU 133 via the communication circuit 138. The lens driving stop signal at this time functions as a lens driving time limiter for preventing the release time lag from becoming longer than necessary. The LCPU 133 stops the driving of the focus adjustment lens 102 based on the lens driving stop signal input from the AF / AECPU 151 (FIG. 6B (n ₂ )).

In step S163, the main body CPU 139 instructs the mirror control circuit 145 to perform mirror-up drive control in parallel with steps S160 to S162. The mirror control circuit 145 performs mirror-up driving based on a command input from the main body CPU 139. (FIG. 6 (B) (o ₂ ))
In step S164, the AF / AECPU 151 calculates a shutter speed by performing a photometric calculation based on the subject brightness information acquired by the photometric circuit 159. Then, the AF / AECPU 151 outputs the calculated shutter speed to the main body CPU 139. The main body CPU 139 drives the focal plane shutter 108 via the shutter control circuit 146 based on the shutter speed input from the AF / AECPU 151. The main body CPU 139 controls the image sensor 109 via the image sensor control circuit 143, and acquires image data of the subject image (FIG. 6B (p ₂ )). The main body CPU 139 outputs the acquired imaging data to the image processing circuit 147 and causes the image processing circuit 147 to execute predetermined image processing. The main body CPU 139 stores the image data processed by the image processing circuit 147 in an external storage means (not shown) such as the RAM 142 or a compact flash. Further, the main body CPU 139 outputs the processed image by the display circuit 148 and displays it on a display unit (not shown) such as a TFT monitor. Thereafter, the process proceeds to step S147 and step S148. As described above, when the 2R switch continues to be on in the continuous shooting mode, steps S147 to S164 are repeated. This corresponds to repeating (q _n ) to (v _n ) and (l _{n + 1} ) to (p _{n + 1} ) in FIG.

Next, the operation when the result of determination in step S146 is not continuous shooting mode will be described with reference to FIG. FIG. 7C shows an operation sequence when the 1R switch 152 is on instead of the continuous shooting mode. If the result of determination in step S146 is not continuous shooting mode, in step S165, the AF / AECPU 151 outputs an aperture opening signal to the LCPU 133 via the communication circuit 138 in the same manner as in step S147. Based on the aperture opening signal input from the AF / AECPU 151, the LCPU 133 instructs the aperture driving circuit 135 to drive the aperture 132 to open (FIG. 7C (q ₁ )). In parallel with step S165, in step S166, the main body CPU 139 instructs the mirror control circuit 145 to perform mirror-down driving as in step S148 (FIG. 7C (r ₁ )).

Subsequently, in step S167, the main body CPU 139 determines the state of the 1R switch 152. If it is determined in step S167 that the 1R switch 152 is not on, the process proceeds to a shooting standby sequence and waits for the next camera operation by the user. On the other hand, if it is determined in step S167 that the 1R switch 152 is on, the process proceeds to step S102 of the 1R sequence. However, in this case, the AF / AECPU 151 outputs the predicted pulse number P3 calculated in step S140 to the LCPU 133 via the communication circuit 138. The LCPU 133 sets the predicted pulse number P3 input from the AF / AECPU 151 as the drive pulse number, and controls the lens drive circuit 136 based on this to drive the focus adjusting lens 102 (FIG. 7C (t ₁ )). In parallel with this, steps 1102 to S109 of the 1R sequence are performed (FIG. 7C (f _{n + 1} ) and (g _{n + 1} )), and lens driving is continued (FIG. 7C (h _{n + 1} )).

  In parallel with step S150 and step S152, main body CPU 139 determines the state of 2R switch 153 in step S168. If it is determined in step S168 that the 2R switch 153 is on, the process proceeds to step S153. On the other hand, if the 2R switch 153 is not in the ON state in the determination in step S168, the process proceeds to step S167.

As described above, according to the present embodiment, when the 1R switch is on and the 2R switch is off (except during exposure), in the moving object prediction calculation, the latest defocus amount obtained during the moving object prediction calculation is obtained. The moving object prediction is performed using the target pulse number obtained before that without including the latest target pulse number. That is, Stated example of FIG. 6 (A), when the object movement presumption calculation in "(g ₄₎ operation" is the target number of pulses calculated in "(g ₄₎ calculation" performs calculation without using. Then, the lens is driven based on the obtained result. On the other hand, at the time of exposure when the 2R switch is turned on, in the moving object prediction calculation, the latest target pulse number obtained from the latest defocus amount obtained at the time of the moving object prediction calculation is obtained before that. The moving object is predicted using the target pulse number. That is, Stated example of FIG. 6 (B), when the object movement presumption calculation in "(k ₁₎ operation" is the target number of pulses calculated in "(k ₁₎ calculation" performs computation using. Then, the lens is driven based on the obtained result. As a result, in the continuous AF mode using the moving object prediction, the moving object prediction calculation is performed without including the latest target pulse number obtained from the latest defocus amount except during exposure, so that the followability does not deteriorate. In addition, since the moving object prediction calculation is performed including the latest target pulse number obtained from the latest defocus amount during exposure, it can cope with a sudden change in subject speed immediately before shooting compared to the conventional continuous AF mode. Can do. Therefore, the automatic focusing apparatus for a camera according to the present embodiment can realize highly accurate moving object prediction control.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Here, in the description of the second embodiment, the description is limited to the differences from the first embodiment. In the present embodiment, in a single-lens reflex camera equipped with the automatic focus adjustment apparatus according to the present invention, operation is performed so that a mirror driving period and a lens driving period that consume a large current do not overlap each other. This embodiment is suitable when a small battery having a low current supply capability is used. The operation of the continuous AF mode of such a camera will be described. The 1R sequence operation of the present embodiment is the same as the 1R sequence operation of the first embodiment. The 2R sequence operation of the present embodiment will be described with reference to the flowchart shown in FIG. 9 and the operation sequence shown in FIG. In addition, the same code | symbol is attached | subjected about the part same as 1st Embodiment, and the description is abbreviate | omitted.

Steps S131 to S139 are the same as those in the first embodiment. In step S201, the AF / AECPU 151 performs a moving object prediction calculation in the same manner as in step S140 of the first embodiment. That is, the moving object prediction is performed using the target pulse number time-series data including the latest target pulse number and stored in the RAM 158, and the predicted pulse number is calculated (FIG. 10A (k ₁ )). There are two predicted pulses to be calculated here. One is the predicted number of pulses at the start of exposure. The other is the predicted number of pulses at the time when the first target number of pulses is calculated after mirror down after completion of exposure. As in the case of the first embodiment, the prediction formula used for the moving object prediction calculation may be a primary expression, a secondary expression, or a higher order expression.

In step S202, the AF / AECPU 151 counts a predetermined lens driving time using an internal timer. During this time, the lens is driven (FIG. 10A (h _n )). Here, the predetermined lens driving time is, for example, the longest time required for the remaining processing of the 1R sequence in steps S132 to S201, acquisition of the target pulse number, and moving object prediction.

When the counting of the lens driving time in step S202 is completed, in step S203, the AF / AECPU 151 transmits a lens driving stop signal to the LCPU 133 via the communication circuit 138. Based on the lens drive stop signal input from the AF / AECPU 151, the LCPU 133 controls the lens drive circuit 136 to stop driving the focus adjustment lens 102 (FIG. 10A (w ₁ )).

In step S204, the main body CPU 139 instructs the mirror control circuit 145 to perform mirror-up drive control. The mirror control circuit 145 performs mirror-up driving based on a command input from the main body CPU 139 (FIG. 10 (A) (o ₁ )).

  In parallel with step S204, steps S205 to S143 are performed. In step S205, the AF / AECPU 151 counts the time until the mirror-up drive current in step S204 decreases to a predetermined level using an internal timer. As a result, as shown in FIG. 10A, the lens drive and the narrow-down drive are not executed during the period when the inrush current at the start of the mirror up drive is generated.

In step S206, the AF / AECPU 151 calculates the aperture value based on the subject luminance information acquired by the photometry circuit 159. Then, the AF / AECPU 151 outputs the calculated aperture value, the predicted pulse number P2 obtained by the moving object prediction calculation in step S201, and the lens driving instruction to the LCPU 133 via the communication circuit 138. The LCPU 133 sets the predicted pulse number P2 input from the AF / AECPU 151 as the drive pulse number, and controls the lens drive circuit 136 based on this to drive the focus adjustment lens 102 (FIG. 10A (l ₁ )). Further, the LCPU 133 performs the diaphragm drive control of the diaphragm 132 by the diaphragm drive circuit 135 based on the diaphragm value input from the AF / AECPU 151 (FIG. 10A (m ₁ )). Hereinafter, as in the case of the first embodiment, in step S142, the AF / AECPU 151 causes the internal timer to drive the lens (for example, the time until the bounce of the main mirror 104 and the sub mirror 105 stops after the mirror up drive). Count. After the elapse of the lens driving time counted in step S142, in step S143, the AF / AECPU 151 transmits a lens driving stop signal for stopping the driving of the focus adjustment lens 102 to the LCPU 133 via the communication circuit 138. The LCPU 133 stops driving the focus adjustment lens 102 based on the lens drive stop signal input from the AF / AECPU 151 (FIG. 10A (n ₁ )). Steps S145 to S158 are the same as those in the first embodiment.

In step S207, the AF / AECPU 151 outputs the predicted number of pulses P3 obtained in step S201 to the LCPU 133 via the communication circuit 138, as in step S151. The LCPU 133 uses the predicted pulse number P3 input from the AF / AECPU 151 as the drive pulse number, and controls the lens drive circuit 136 based on this to drive the focus adjustment lens 102 (FIG. 10A (t ₁ )).

In step S208, the AF / AECPU 151 performs the moving object prediction calculation using the target pulse number time-series data stored in the RAM 158, as in step S201 (FIG. 10A (v ₁ )). That is, a prediction pulse P2 that is a predicted value of the target pulse number at the next exposure start time and a prediction value that is a predicted value of the target pulse number at the time when the first target pulse number after mirror down after the exposure is calculated is calculated. The pulse P3 is calculated.

In step S209, the AF / AECPU 151 counts a predetermined lens driving time using an internal timer, as in step S202. During this time, the lens is driven (FIG. 10A (t ₁ )).

When the counting of the lens driving time in step S209 is completed, in step S210, the AF / AECPU 151 transmits a lens driving stop signal to the LCPU 133 via the communication circuit 138, similarly to step S203. Based on the lens drive stop signal input from the F / AECPU 151, the LCPU 133 controls the lens drive circuit 136 to stop driving the focus adjustment lens 102 (FIG. 10A (w ₂ )).

In step S211, the main body CPU 139 instructs the mirror control circuit 145 to perform mirror-up drive control, as in step S204. The mirror control circuit 145 performs mirror-up driving based on a command input from the main body CPU 139 (FIG. 10 (A) (o ₂ )).

  In parallel with step S211, steps S212 to S162 are performed. In step S212, the AF / AECPU 151 counts the time until the mirror-up drive current in step S211 drops to a predetermined level, using an internal timer, as in step S205. As a result, as shown in FIG. 10A, the lens drive and the narrow-down drive are not executed during the period when the inrush current at the start of the mirror up drive is generated.

In step S213, the AF / AECPU 151 calculates the aperture value based on the subject luminance information acquired by the photometry circuit 159, as in step S206. Then, the AF / AECPU 151 outputs the calculated aperture value, the predicted pulse number P2 obtained by the moving object prediction calculation in step S208, and the lens driving instruction to the LCPU 133 via the communication circuit 138. The LCPU 133 sets the predicted pulse number P2 input from the AF / AECPU 151 as the drive pulse number, and controls the lens drive circuit 136 based on this to drive the focus adjustment lens 102 (FIG. 10A (l ₂ )). Further, the LCPU 133 performs the diaphragm drive control of the diaphragm 132 by the diaphragm drive circuit 135 based on the diaphragm value input from the AF / AECPU 151 (FIG. 10A (m ₂ )). Thereafter, as in step S142 and step S143, in step S161, the AF / AECPU 151 counts the lens driving time with an internal timer. After the elapse of the lens driving time counted in step S161, in step S162, the AF / AECPU 151 transmits a lens driving stop signal for stopping the driving of the focus adjustment lens 102 to the LCPU 133 via the communication circuit 138. The LCPU 133 stops the driving of the focus adjustment lens 102 based on the lens driving stop signal input from the AF / AECPU 151 (FIG. 10A (n ₂ )).

Steps S164 to S168 are the same as those in the first embodiment. Therefore, if the 2R switch is kept on in the continuous shooting mode, steps S147 to S164 are repeated. This corresponds to repeating (q _n ) to (v _n ) and (l _{n + 1} ) to (p _{n + 1} ) in FIG. When not in the continuous shooting mode, as shown in FIG. 10B, the lens drive and the narrow-down drive are performed during the period when the inrush current is generated at the start of the “(o ₁ ) mirror up” drive. Is not executed. Further, after “(t ₁ ) lens driving”, the lens driving is continued in accordance with the 1R sequence (FIG. 10B (h _{n + 1} )).

  As described above, according to the present embodiment, even when the lens drive needs to be temporarily stopped at the start of mirror-up and mirror-down drive due to insufficient current supply capability of the battery, the same as in the first embodiment. The effect of can be obtained. That is, as in the first embodiment, in the continuous AF mode using the moving object prediction, the follow-up performance is not deteriorated and the subject speed immediately before shooting is abrupt as compared with the conventional continuous AF mode. It is possible to realize highly accurate moving object prediction control that can cope with changes.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiment, the problem described in the column of problems to be solved by the invention can be solved and the effect of the invention can be obtained. The configuration in which this component is deleted can also be extracted as an invention. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 100 ... Camera body, 101 ... Interchangeable lens part, 102 ... Focus adjustment lens, 103 ... Zoom lens, 104 ... Main mirror, 105 ... Sub mirror, 106 ... Focus detection optical system, 107 ... Focus detection sensor (AF sensor), 108 ... Focal plane shutter, 109 ... imaging device, 110 ... screen mat, 111 ... finder optical system, 112 ... eyepiece lens, 113 ... focus detection area mark, 120 ... field mask, 121 ... condenser lens, 122 ... total reflection mirror, 123 ... Infrared cut filter, 124: Separator aperture mask, 125 ... Separator lens, 126 ... Photography lens, 127 ... Opening, 124a, 124b, 124c, 124d ... Four openings, 125a, 125b, 125c, 125d ... Four separators Lens, 128a, 12 b, 128c, 128d... Four photodiode array units, 129... Primary imaging plane at a distance equivalent to the image sensor 109, 130... Zoom drive rotation ring, 131. Manual focus (MF) rotation ring, 133. Lens CPU (LCPU), 134: Zoom position detection circuit, 135: Aperture drive circuit, 136 ... Lens drive circuit, 137 ... Lens position detection circuit, 138 ... Communication circuit, 139 ... Main body CPU, 140 ... Communication line, 141 ... Flash ROM (FROM), 142 ... RAM, 143 ... image sensor control circuit, 144 ... strobe control circuit, 145 ... mirror control circuit, 146 ... shutter control circuit, 147 ... image processing circuit, 148 ... display circuit, 149 ... operation switch detection Circuit 150 ... Power supply circuit 151 ... AF / AECPU 152 ... First release Switch (1R switch), 153 ... Second release switch (2R switch), 154 ... Battery, 155 ... Communication line, 156 ... Communication line, 157 ... Flash ROM (FROM), 158 ... RAM, 159 ... Photometry circuit, 160 ... Focus detection circuit 161... Auxiliary light circuit.

Claims (3)

Focus detection means for detecting the focus state of the focus lens;
The position of the focus lens calculated based on the focus state detected by the focus detection unit and the position of the focus lens at the time of focus detection when the focus detection unit detected the focus state is the in-focus position. Target drive position acquisition means for acquiring a target drive position,
Based on a plurality of target drive positions acquired in time series by the target drive position acquisition means, a moving object prediction that calculates a predicted target drive position at which the position of the focus lens at a time point after the focus detection time point becomes a focus position Means,
Lens drive means for moving the position of the focus lens to the predicted target drive position calculated by the moving object prediction means;
Comprising
The moving object predicting means, as the predicted target drive position, during a moving object prediction operation that repeatedly calculates the predicted target drive position,
If the exposure instruction has not been received, the first predicted target drive position is calculated based on the target drive position obtained after the start of the moving object prediction operation except for the latest obtained target drive position;
When the exposure instruction is received, a second predicted target drive position is calculated based on the target drive position obtained after the start of the moving object predicting operation including the latest obtained target drive position. To
An automatic focusing device for a camera. The focus detection means has a focus detection sensor,
The focus state detection operation by the focus detection means includes an accumulation operation of the focus detection sensor, a read operation for reading a signal from the focus detection sensor, and a calculation operation of the focus state based on the read signal. Including,
The moving object predicting means is based on the target drive position obtained after the start of the moving object predicting operation including the most recently obtained target drive position at the time of calculating the second predicted target drive position. Calculating a third predicted target drive position that is a predicted target drive position at the time of calculation of the first predicted target drive position after the exposure ends;
When the lens driving instruction means receives the exposure instruction,
Instructing the movement of the focus lens to the second predicted target drive position, and instructing to stop the movement of the focus lens at the exposure time when actual exposure is performed,
In the case of instructing the movement of the focus lens to the predicted target position even after the exposure ends, the third predicted target drive position is reached at the end of the accumulation operation in the first focus detection means after the exposure ends. Instruct to move the focus lens
During the movement of the focus lens to the third predicted target drive position,
The readout operation and the computation operation in the focus detection means;
An operation of acquiring a target drive position by the target drive position acquisition means;
A calculation operation of a predicted target drive position by the moving body prediction means;
Carry out the
The automatic focusing apparatus for a camera according to claim 1, wherein: A focus detection sensor in the focus detection means;
An optical path switching means for switching the optical path of the subject luminous flux so as to guide the subject luminous flux to the focus detection sensor except during the exposure to actually perform exposure, and to guide the subject luminous flux to the imaging surface during the exposure;
Further comprising
The moving object predicting unit calculates the second predicted target drive position at a time immediately before the switching operation for switching the optical path so that the optical path switching unit guides the subject light flux to the imaging surface. The automatic focusing device for a camera according to claim 1.

Images