JP5169541B2 - Imaging device - Google Patents

Description

The present invention relates to an imaging apparatus including an imaging device.

  Conventionally, in order to perform contrast-based autofocus at a fast cycle, there is known a solid-state image sensor that reads only the output of a pixel in a predetermined area as information for autofocus among pixels arranged in a two-dimensional shape in the image sensor. (See Patent Document 1). There is also known an imaging device in which a focus detection pixel that outputs a focus detection signal based on a phase difference method is disposed in an image sensor, and phase difference autofocus is performed based on the output of the focus detection pixel ( Patent Document 2).

JP 2007-150643 A JP 2007-282109 A

  The pixel output readout method disclosed in Patent Document 1 is applied to an imaging apparatus that performs contrast autofocus. Therefore, even if this is applied to an imaging apparatus that performs phase-difference autofocus based on the output of focus detection pixels arranged in an imaging element, such as the imaging apparatus disclosed in Patent Document 2. Therefore, it is impossible to read out an appropriate pixel output corresponding to the photographing sequence.

An imaging apparatus according to the present invention includes a first pixel column having a first pixel group that is a plurality of focus detection pixels, a second pixel column having a plurality of second pixel groups different from the first pixel group, an imaging element and a third pixel row having a plurality of different third pixel group and the pixel group and second pixel group, the focus detection of the phase difference method using a first signal output from the first pixel group A focus detection unit to perform, a photometry unit that performs photometry using the second signal output from the second pixel group, a third signal output from the third pixel group, and a second signal output from the second pixel group Display control unit for controlling live view display using the first mode, focus detection by the focus detection unit, photometry by the photometry unit, and first mode for performing live view display by the display control unit, photometry by the photometry unit, and display A second mode for performing live view display by the control unit; and A selection unit that selects any one of the third modes in which photometry is performed by the photometry unit, and when the first mode is selected by the selection unit, the first pixel column, the second pixel column, and the third pixel First decimation control is performed so that a column is selected, and when the second mode is selected by the selection unit, second decimation control is performed so that the second pixel column and the third pixel column are selected, and the selection unit And a thinning control unit that performs third thinning control so that the second pixel column is selected when the third mode is selected.

  ADVANTAGE OF THE INVENTION According to this invention, in the imaging device which performs a phase difference type autofocus based on the output of the focus detection pixel arrange | positioned in an image pick-up element, the suitable pixel output according to an imaging | photography sequence can be read. .

  FIG. 1 is a block diagram showing a configuration of a camera to which an image sensor according to an embodiment of the present invention is applied. The camera shown in FIG. 1 includes a camera body 1 and a lens unit 2. The lens unit 2 includes photographing optical systems 3 and 5, a lens driving mechanism 4, and a diaphragm 6. The lens 3 constituting the photographing optical systems 3 and 5 functions as a focus adjustment lens.

  The camera body 1 includes a main mirror 7, a sub mirror 8, a focus detection device 9, a finder screen 10, a pentaprism 11, an eyepiece 12, an eyepiece 13, a photometric lens 14, a photometric sensor 15, a liquid crystal display 16, an image sensor 17, It has a shutter 18, a live view changeover switch 19, an image processing unit 21, a CPU 22, and a memory 23. The shutter 18 is provided with a front curtain 18a and a rear curtain 18b.

  The lens driving mechanism 4 moves the focus adjustment lens 3 in the optical axis direction under the control of the CPU 22. As the focus adjustment lens 3 moves, the focus adjustment state of the photographing optical system changes. A light beam from the subject is guided into the camera body 1 through the focus optical systems 3 and 5. A part of this light beam is reflected by the main mirror 7 which is a half mirror, and the rest is transmitted through the main mirror 7.

  The light beam reflected by the main mirror 7 projects a subject image on the finder screen 10. This subject image is reflected by the pentaprism 11 and then guided to the eyepiece 13 through the eyepiece 12. A user who is a photographer can view the subject image as an optical viewfinder image by looking into the eyepiece 13.

  The subject image projected on the finder screen 10 is reflected by the pentaprism 11 and then guided to the photometric sensor 15 via the photometric lens 14. The photometric sensor 15 outputs a photometric signal corresponding to the brightness of the subject image to the CPU 22. The CPU 22 obtains the brightness of the subject image, that is, the brightness of light passing through the photographing optical systems 3 and 5 based on the photometric signal output from the photometric sensor 15.

  On the other hand, the light beam transmitted through the main mirror 7 is reflected by the sub mirror 8 and guided to the focus detection device 9. The focus detection device 9 detects the focus adjustment state of the photographing optical systems 3 and 5 by a known phase difference detection method using pupil division. That is, the focus detection device 9 detects the shift amount of the pair of images due to the light beams passing through different areas of the exit pupils of the photographing optical systems 3 and 5. The detection result of the deviation amount is output from the focus detection device 9 to the CPU 22 as a focus detection signal. The CPU 22 calculates the defocus amount based on the focus detection signal output from the focus detection device 9 and controls the lens driving mechanism 4 to adjust the position of the focus adjustment lens 3.

  At the time of shooting, the aperture 6 is adjusted to a predetermined aperture value, and the main mirror 7 and the sub mirror 8 are flipped upward and retracted from the imaging optical path. In this state, when the shutter 18 is opened for a predetermined exposure time, the light flux through the photographing optical systems 3 and 5 is guided to the image sensor 17 and a subject image is formed on the image sensor 17. The image sensor 17 captures the subject image and outputs an image signal to the image processing unit 21. The operations of the diaphragm 6 and the shutter 18 are controlled by the CPU 22.

  The image processing unit 21 performs predetermined image processing based on the image signal output from the image sensor 17 and generates a captured image. This captured image is output to the CPU 22 and displayed on the liquid crystal display 16 and recorded on a recording medium (not shown) under the control of the CPU 22.

  The CPU 22 executes various controls as described above. The memory 23 is used as a work area for processing and control performed by the image processing unit 21 and the CPU 22, and temporarily stores various information according to the contents of the processing and control.

  The live view selector switch 19 is a switch for switching between a normal shooting mode and a live view mode. When the live view changeover switch 19 is set to the “OFF” side by a user operation, a normal shooting mode is set for the camera body 1. At this time, the photographing operation as described above is performed in the camera body 1. That is, before the user gives a shooting instruction by operating a shutter button (release button) (not shown), the main mirror 7 and the sub mirror 8 are arranged on the shooting optical path. In this state, an optical viewfinder image based on the subject image projected on the viewfinder screen 10 is provided to the user, and focus adjustment of the photographing optical system is performed based on the focus detection signal output from the focus detection device 9. When the user gives a shooting instruction by operating the shutter button, the main mirror 7 and the sub mirror 8 are retracted from the shooting optical path, and a captured image generated based on an image signal output from the image sensor 17 is recorded on a recording medium. .

  On the other hand, when the live view switch 19 is set to the “ON” side, the live view mode is set for the camera body 1. This live view mode is a shooting mode for displaying an image of a subject on the liquid crystal display 16 in real time before shooting. That is, before the user gives a shooting instruction by operating the shutter button, the main mirror 7 and the sub mirror 8 are retracted from the shooting optical path and the shutter 18 is opened. In this state, based on the image signal output from the image sensor 17, a captured image is generated in real time by the image processing unit 21 and displayed on the liquid crystal display 16 under the control of the CPU 22. The image displayed at this time is hereinafter referred to as a live view image. Note that when a live view image is displayed on the liquid crystal display 16, the optical viewfinder image cannot be seen. When the user gives a shooting instruction by operating the shutter button, the captured image is recorded on the recording medium.

  FIG. 2 is a diagram illustrating a state when the live view mode is set. In this figure, the main mirror 7 and the sub mirror 8 are retracted from the photographing optical path, and the shutter 18 is opened. Therefore, the light beam guided into the camera body 1 via the photographing optical system reaches the image sensor 17 without being reflected by the main mirror 7 and the sub mirror 8 or blocked by the shutter 18. A subject image is picked up by the image pickup device 17 based on the luminous flux, and the generated picked-up image is displayed on the liquid crystal display 16 in real time as a live view image.

  In the live view mode described above, the focus adjustment state cannot be detected by the focus detection device 9 because the sub mirror 8 is retracted from the photographing optical path. Therefore, in this embodiment, in addition to the imaging pixels for outputting the image signal, focus detection pixels for performing focus detection by the phase difference method are arranged in the imaging element 17. Focus adjustment in the live view mode is realized by outputting a focus detection signal from the focus detection pixels.

  In the live view mode, since the main mirror 7 is retracted from the photographing optical path, the photometric sensor 15 cannot output a photometric signal. Therefore, the CPU 22 detects the brightness of the subject image based on the image signal output from the image sensor 17. At this time, an image signal is output only from a part of the imaging pixels without using all of the imaging pixels arranged in the imaging element 17.

  FIG. 3 is a diagram illustrating a configuration of a control system in the camera body 1. In this control system, the CPU 22 includes a shooting mode setting unit 22a, a signal readout mode setting unit 22b, a focus adjustment calculation unit 22c, a photometry calculation unit 22d, a lens drive control unit 22e, a shutter drive control unit 22f, an aperture drive control unit 22g, Each of the functional blocks of the photographed image recording control unit 22h, the LCD driving unit 22i, and the operation detection unit 22j is virtually included.

  The shooting mode setting unit 22 a is a functional block that sets a shooting mode for the camera body 1. That is, the shooting mode setting unit 22 a sets either a normal shooting mode or a live view mode according to the state of the live view changeover switch 19, and performs an operation corresponding to the setting on each unit of the camera body 1. Instruct.

  The signal readout mode setting unit 22 b is a functional block that sets a mode for reading signals from the image sensor 17. As described above, the imaging element 17 includes the imaging pixels and the focus detection pixels. The signal readout mode setting unit 22b sets a signal readout mode for the image sensor 17 according to the operation state of the camera body 1. As a result, the image sensor 17 determines which of the plurality of pixels of the image sensor 17 is to output a signal. The specific contents of this signal readout mode setting will be described later in detail.

  The focus adjustment calculation unit 22c calculates a defocus amount indicating the focus adjustment state of the imaging optical systems 3 and 5 based on the focus detection signal output from the focus detection device 9 or the focus detection pixel of the image sensor 17. . As described above, when the normal shooting mode is set, a focus detection signal is output from the focus detection device 9, and when the live view mode is set, the focus detection pixel of the image sensor 17 is used. A focus detection signal is output.

  Based on the photometric signal output from the photometric sensor 15 or the image signal output from the imaging pixel of the image sensor 17, the photometric calculator 22 d passes through the brightness of the subject image, that is, through the imaging optical systems 3 and 5. Calculate the brightness of light. As described above, when the normal photographing mode is set, a photometric signal is output from the photometric sensor 15, and when the live view mode is set, the photometric calculation is performed from the imaging pixel of the image sensor 17. Are output.

  The lens drive control unit 22e controls the operation of the lens drive mechanism 4 based on the defocus amount calculated by the focus adjustment calculation unit 22c. Thereby, the focus adjustment lens 3 is moved to an appropriate position by the lens driving mechanism 4, and the focus of the photographing optical systems 3 and 5 is adjusted according to the subject.

  The shutter drive control unit 22f controls the operation of the shutter 18 based on the brightness of the subject image calculated by the photometry calculation unit 22d. The aperture drive control unit 22g controls the operation of the aperture 6 based on the brightness of the subject image calculated by the photometry calculation unit 22d. With these operations, exposure control during shooting is performed. When the live view mode is set, the shutter 18 is opened.

  The captured image recording control unit 22h performs control when recording a captured image acquired by capturing on a recording medium. Further, the captured image recorded on the recording medium is also read out by the captured image recording control unit 22h.

  The LCD drive unit 22 i performs image display control on the liquid crystal display 16. That is, when the live view mode is set, the live view image generated by the image processing unit 21 is displayed on the liquid crystal display 16 by the image display control performed by the LCD driving unit 22i. Note that the LCD drive unit 22i is also used when displaying an image other than the live view image on the liquid crystal display 16, for example, when displaying a captured image recorded on a recording medium or displaying a menu screen.

  The operation detection unit 22j detects operation states of various operation members including the live view changeover switch 19, for example, an operation state of a shutter button. Note that the shutter button can take two types of operation states, half-press and full-press. Half-press is an operation state corresponding to a focus adjustment instruction operation, and full-press is an operation state corresponding to a shooting instruction operation. That is, when the operation detection unit 22j detects that the shutter button is half-pressed, the defocus amount is calculated by the focus adjustment calculation unit 22c. Then, the lens drive control unit 22e controls the operation of the lens drive mechanism 4, whereby the focus adjustment of the photographing optical systems 3 and 5 is performed. When the operation detection unit 22j detects that the shutter button is fully pressed, the shooting mode setting unit 22a instructs the respective units of the camera body 1 to perform a shooting operation according to the shooting mode setting state. The The acquired captured image is recorded on the recording medium by the captured image recording control unit 22h.

  Next, the signal readout mode set for the image sensor 17 will be described. FIG. 4 is a diagram illustrating a correspondence relationship between an arrangement example of pixels in the image sensor 17 and a row of an image read in each signal readout mode. FIG. 4 illustrates only a part of the pixels in the image sensor 17.

  As shown in FIG. 4, imaging pixels corresponding to each color of R (red), G (green), and B (blue) are alternately arranged in the imaging element 17 according to the Bayer array. Each of these imaging pixels is provided with a corresponding color filter and a photodiode. Light from the photographing optical systems 3 and 5 that has passed through the color filter is photoelectrically converted by a photodiode and output as an image signal corresponding to the light intensity. In this way, each imaging pixel outputs an image signal based on the light that has passed through the imaging optical systems 3 and 5.

  In addition to the above-described imaging pixels, focus detection pixels indicated by symbols FG1 and FG2 are also arranged in the row indicated by the symbol F1. The focus detection pixels FG1 and FG2 have openings at positions deviated in the left and right directions from the center of the pixel, and photodiodes are provided corresponding to the openings. With such a structure, the photodiodes of the focus detection pixels FG1 and FG2 receive a pair of light beams that have passed through different portions of the pupils of the photographing optical systems 3 and 5, and a signal corresponding to the light intensity is phase-difference type. Can be output as a focus detection signal. Thus, the focus detection pixels FG1 and FG2 output a focus detection signal based on the phase difference method based on the light passing through the photographing optical systems 3 and 5. Unlike the imaging pixels, the focus detection pixels FG1 and FG2 are not provided with a color filter. That is, the focus detection pixel has sensitivity to any of R, G, and B colors.

  For the image sensor 17 having the pixel arrangement as described above, the CPU 22 selects one of a plurality of signal readout modes according to the operation state of the camera body 1 by the function of the signal readout mode setting unit 22b described above. Select alternatively. The image sensor 17 switches the row of pixels from which signals are read out in each readout cycle in accordance with the set signal readout mode.

  For example, when the live view mode is set as the shooting mode of the camera body 1, the CPU 22 sets one of the three signal readout modes of mode 1, mode 2, and mode 3 for the image sensor 17. In FIG. 4, the rows of pixels to be read in modes 1 to 3 are denoted by reference symbols E1B, E1R, F1, L1B, and L1R. Note that FIG. 4 shows a part of the image sensor 17 (upper left) for the sake of simplicity. The entire image sensor has an element structure in which the arrangement as shown in FIG. 4 is repeated. In the following description, focus detection pixels FG1 and FG2 belonging to the row F1 are referred to as a first pixel group. The imaging pixels belonging to the rows E1B and E1R are referred to as a second pixel group, and the imaging pixels belonging to the rows E1B, E1R, L1B, and L1R are referred to as a third pixel group. That is, the third pixel group includes the second pixel group, and further includes a plurality of imaging pixels that do not constitute the second pixel group.

  Mode 1 is a signal readout mode for performing AF processing, AE processing, and live view image display. When mode 1 is set, the image sensor 17 outputs only the signals of the pixels belonging to the rows E1B, E1R, F1, L1B, and L1R among the pixels in FIG. That is, in mode 1, the focus detection signals output from the focus detection pixels FG1 and FG2 constituting the first pixel group and the image signals output from the image pickup pixels constituting the third pixel group are image sensors. 17 is read out. In the live view image display, the pixels in the two rows between the rows E1R and F1, the pixels in the rows between the rows F1 and L1B, and the pixels in the rows below the row L1R are not read out. This is because thinning readout is performed by thinning readout rows at a ratio. A similar readout operation is also performed in a pixel portion not shown in FIG.

  In mode 1, the CPU 22 calculates the defocus amount by the function of the focus adjustment calculation unit 22c based on the focus detection signals output from the focus detection pixels FG1 and FG2 constituting the first pixel group. Based on this defocus amount, the operation of the lens drive mechanism 4 is controlled by the function of the lens drive control unit 22e, whereby the focus adjustment lens 3 is moved to an appropriate position to perform AF processing. Further, the CPU 22 adjusts the brightness of the subject image by the function of the photometric calculation unit 22d based on the image signals output from the imaging pixels constituting the second pixel group, that is, the imaging pixels belonging to the rows E1B and E1R. Calculate. Based on this brightness, the operations of the shutter 18 and the aperture 6 are controlled by the functions of the shutter drive control unit 22f and the aperture drive control unit 22g to perform AE processing. In mode 1, the image processing unit 21 performs a live view image based on image signals output from the imaging pixels constituting the third pixel group, that is, the imaging pixels belonging to the rows E1B, E1R, L1B, and L1R. Is generated.

  Mode 2 is a signal readout mode for performing AE processing and live view image display. When mode 2 is set, the image sensor 17 outputs only the signals of the pixels belonging to the rows E1B, E1R, L1B, and L1R among the pixels in FIG. That is, in mode 2, only the image signal output from the imaging pixels that constitute the third pixel group is read out from the imaging element 17. In other words, the rows other than the rows E1B, E1R, L1B, and L1R in FIG. A similar readout operation is performed in the same manner for pixel portions not shown in FIG.

  In mode 2, the CPU 22 performs the above-described processing based on the image signals output from the imaging pixels constituting the second pixel group in the third pixel group, that is, the imaging pixels belonging to the rows E1B and E1R. Such AE processing is performed. In mode 2, the image processing unit 21 performs live view based on the image signals output from the imaging pixels constituting the third pixel group, that is, the imaging pixels belonging to the rows E1B, E1R, L1B, and L1R. Generate an image. At this time, the AF processing is not performed in the CPU 22.

  Mode 3 is a signal readout mode for performing AE processing. When mode 3 is set, the image sensor 17 outputs only the signals of the pixels belonging to the rows E1B and E1R among the pixels in FIG. That is, in mode 3, only the image signal output from the imaging pixels constituting the second pixel group is read from the imaging element 17. A similar readout operation is performed in the same manner for pixel portions not shown in FIG.

  In mode 3, the CPU 22 performs the above-described AE processing based on the image signals output from the imaging pixels constituting the second pixel group, that is, the imaging pixels belonging to the rows E1B and E1R. At this time, the AF processing is not performed in the CPU 22. Further, the live view image is not generated by the image processing unit 21.

  Note that the modes 1 to 3 described above are all set as a signal readout mode in units of frames. The frame here is an update cycle of the live view image, and corresponds to a signal read cycle from the image sensor 17 when the live view image is displayed. That is, switching of each signal reading mode of modes 1 to 3 is performed in units of frames.

  Switching of the signal readout mode in the image sensor 17 is performed by the operation of a scanning circuit provided in the image sensor 17. This scanning circuit has a vertical scanning circuit that scans each pixel of the image sensor 17 in the vertical direction and a horizontal scanning circuit that scans each pixel of the image sensor 17 in the horizontal direction. That is, switching of the signal readout mode is realized by switching the row of pixels selected by the vertical scanning circuit.

  In the image sensor 17, the arrangement of pixels as shown in FIG. 4 is repeated. That is, a plurality of focus detection pixels belonging to the first pixel group are arranged at positions corresponding to a preset focus detection area. In addition, a plurality of imaging pixel rows belonging to the third pixel group are arranged at a predetermined interval, and some of the rows function as the second pixel group. Since the pixel arrangement shown in FIG. 4 is an example, another arrangement may be used.

  FIG. 5 is a diagram showing the relationship between the operation of the camera body 1 and the switching timing of the signal readout mode. This figure will be described below.

  When the power is turned on, the camera body 1 starts to accumulate charges in the photometric sensor 15 at time T1. After a predetermined time has elapsed, a photometric signal corresponding to the accumulated charge is read from the photometric sensor 15 under the control of the CPU 22. The CPU 22 performs photometry calculation based on the read photometry signal by the function of the photometry calculation unit 22d, and calculates the brightness of the subject image. The AE process is performed by repeating such a process at a predetermined cycle.

  When the user switches the live view changeover switch 19 from “OFF” to “ON” at time T2, the CPU 22 switches the shooting mode to the live view mode by the function of the shooting mode setting unit 22a. At this time, the CPU 22 retracts the main mirror 7 and the sub mirror 8 from the photographing optical path and opens the front curtain 18a of the shutter 18. Thereafter, at time T3, charge accumulation in the image sensor 17 is started. At this time, the CPU 22 sets mode 2 of the above-described three types of signal readout modes for the image sensor 17 by the function of the signal readout mode setting unit 22b.

  When mode 2 is set, the image sensor 17 outputs only the image signals from the third pixel group, that is, the imaging pixels belonging to the rows E1B, E1R, L1B, and L1R after a predetermined accumulation time has elapsed. The image processing unit 21 reads out the image signal from the image sensor 17 and performs predetermined image processing to generate data for photometric calculation and data for live view images. Note that the data for photometric calculation is created based on image signals from the imaging pixels constituting the second pixel group in the third pixel group, that is, the imaging pixels belonging to the rows E1B and E1R. . On the other hand, the data for the live view image is created based on the image signals from the imaging pixels constituting the third pixel group, that is, the imaging pixels belonging to the rows E1B, E1R, L1B, and L1R. The created data is stored in the memory 23.

  Based on the data for photometry calculation stored in the memory 23, the CPU 22 performs photometry calculation by the function of the photometry calculation unit 22d, and executes the AE process as described above. Further, the CPU 22 displays the live view image on the liquid crystal display 16 by the function of the LCD drive unit 22 i based on the data for the live view image stored in the memory 23.

  Mode 2 is set for the image sensor 17 until the user operates the shutter button after the user switches the shooting mode to the live view mode, and the above operation is repeated.

  When the user half-presses the shutter button at time T4, from the next frame, the CPU 22 switches the setting of the signal reading mode of the image sensor 17 from mode 2 to mode 1 by the function of the signal reading mode setting unit 22b. When mode 1 is set, the image sensor 17 configures the focus detection signals from the focus detection pixels FG1 and FG2 constituting the first pixel group and the third pixel group after a predetermined accumulation time has elapsed. An image signal from the imaging pixel is output. The image processing unit 21 reads out these signals from the image sensor 17 and performs predetermined image processing to generate data for defocus amount calculation, data for photometry calculation, and data for live view images. Note that the defocus amount calculation data is generated based on focus detection signals from the focus detection pixels FG1 and FG2 constituting the first pixel group. In addition, the data for photometry calculation and the data for live view image are the image signal from the imaging pixels constituting the second pixel group and the imaging constituting the third pixel group, as in mode 2 described above. Each is created based on the image signal from the pixel for use. The created data is stored in the memory 23.

  The CPU 22 calculates the defocus amount by the function of the focus adjustment calculation unit 22c based on the defocus amount calculation data stored in the memory 23, and drives the focus adjustment lens 3 to perform the AF processing as described above. Execute. Similarly to the above-described mode 2, the CPU 22 performs AE processing based on the data for photometry calculation and displays the live view image on the liquid crystal display 16 based on the data for live view image.

  While the user presses the shutter button halfway, the mode 2 is set for the image sensor 17 and the above operation is repeated.

  When the user fully presses the shutter button at time T5, the CPU 22 switches the signal readout mode setting for the image sensor 17 from mode 1 to mode 3 by the function of the signal readout mode setting unit 22b. When mode 3 is set, the image sensor 17 outputs only the image signals from the second pixel group, that is, the imaging pixels belonging to the rows E1B and E1R after a predetermined accumulation time has elapsed. The image processing unit 21 reads out the image signal from the image sensor 17 and performs predetermined image processing to generate data for photometric calculation. The created data is stored in the memory 23. At this time, since the photographing optical system is considered to be in focus with respect to the subject by the operation in the mode 1, the AF process is not performed. In addition, since the shooting instruction is issued from the user by the full pressing operation of the shutter button, the live view image is not updated.

  The CPU 22 performs the photometry calculation by the function of the photometry calculation unit 22d based on the photometry calculation data stored in the memory 23, and executes the AE process, similarly to the above-described modes 2 and 1.

  After the user fully presses the shutter button, mode 3 is set for the image sensor 17 and the above operation is performed.

  It should be noted that after the user fully presses the shutter button, it is desirable to perform a plurality of AE processes in order to obtain an accurate exposure of an image acquired at the time of shooting. However, it is preferable that the release time lag from the full pressing of the shutter button to the photographing is as small as possible. Therefore, by setting mode 3 for the image sensor 17 as described above, the image pickup pixels to be read out in the image sensor 17 are thinned out, and only the image signals from the image pickup pixels belonging to the second pixel group are used. It is effective to perform AE processing based on this.

  After the execution of the AE process, the CPU 22 starts a photographing operation at time T6, and therefore first closes the rear curtain 18b of the shutter 18 by the function of the shutter drive control unit 22f. Thereafter, the shutter 18 is charged, and the front curtain 18a is closed and the rear curtain 18b is opened. At time T7, the CPU 22 adjusts the aperture 6 according to the result of the photometric calculation by the function of the aperture drive control unit 22g.

  When the preparation for photographing is completed, the CPU 22 starts accumulation of the image sensor 17 and starts the travel of the front curtain 18a with respect to the shutter 18 at time T8. When a predetermined exposure time has elapsed from time T8, the CPU 22 causes the shutter 18 to start running the rear curtain 18b at time T9. When the trailing curtain 18b is completely closed, the accumulation of the image sensor 17 is stopped and the reading of the image signal is started. In this case, it is preferable to read out image signals from all the imaging pixels without thinning out the imaging pixels to be read out in the imaging element 17, unlike when the above-described modes 1 to 3 are set.

  The image processing unit 21 performs predetermined image processing on the image signal read from the image sensor 17 and generates captured image data. At this time, since an image signal cannot be obtained for the focus detection pixel portion, it is preferable to perform interpolation based on information on surrounding imaging pixels. The created captured image data is stored in the memory 23. The CPU 22 records the captured image data stored in the memory 23 on a recording medium by the function of the captured image recording control unit 22h.

  When the running of the rear curtain 18b is completed, the CPU 22 immediately charges the shutter 18 so that the front curtain 18a is closed and the rear curtain 18b is opened. Thereafter, the front curtain 18a is opened at time T10 so that the live view image can be displayed again. When the front curtain 18a is opened, charge accumulation in the image sensor 17 is started at time T11, and mode 2 is set for the image sensor 17 from the CPU 22. Thereafter, the same operation as after time T3 is repeated.

  In the embodiment described above, the mode 1, mode 2 and mode 3 can be set for the image sensor 17 as the signal readout mode of the image sensor 17. However, any one or two of these modes can be set. May be set. For example, when the AE process performed after the shutter button is fully pressed is omitted, only mode 1 and mode 2 may be set except for mode 3. Alternatively, other signal readout modes may be settable. For example, in order to execute the AF process, a mode in which only the focus detection signal from the focus detection pixels belonging to the first pixel group may be set.

  In the above embodiment, an example in which pixels to be read out are thinned out in the row direction in the image sensor 17 has been described, but thinning out may be performed in the column direction. Alternatively, thinning may be performed for both the row direction and the column direction.

According to the embodiment and various modifications described above, the following operational effects are obtained.
(1) The imaging device 17 includes a first pixel group including focus detection pixels FG1 and FG2 belonging to the row F1, a second pixel group including a plurality of imaging pixels belonging to the rows E1B and E1R, and a row. A third pixel group including a plurality of imaging pixels belonging to E1B, E1R, L1B, and L1R is disposed. The imaging element 17 reads a focus detection signal output from the focus detection pixels FG1 and FG2 constituting the first pixel group and an image signal output from the imaging pixel constituting the third pixel group. 1, mode 2 for reading out only image signals output from imaging pixels constituting the third pixel group, and mode 3 for reading out only image signals output from imaging pixels constituting the second pixel group; At least one of these modes can be set as a signal readout mode in units of frames. Since it did in this way, in the camera main body 1 which performs a phase difference type autofocus based on the output of the focus detection pixel arrange | positioned in the image pick-up element 17, the suitable pixel output according to an imaging | photography sequence is read. Can do.

(2) The CPU 22 sets one of mode 1, mode 2 and mode 3 for the image sensor 17 by the signal readout mode setting unit 22b. When mode 1 is set for the image sensor 17, the CPU 22 performs shooting based on the focus detection signals output from the focus detection pixels FG1 and FG2 constituting the first pixel group by the focus adjustment calculation unit 22c. The defocus amount indicating the focus adjustment state of the optical systems 3 and 5 is calculated, and the photographic optical system 3 is calculated based on the image signal output from the imaging pixels constituting the second pixel group by the photometric calculator 22d. , 5 to calculate the brightness of light. In addition, the image processing unit 21 generates a live view image based on the image signal output from the imaging pixels constituting the third pixel group. Since it did in this way, in live view mode, AF processing, AE processing, and the display of a live view image can be performed in parallel.

(3) When the mode 2 is set for the image sensor 17, the CPU 22 uses the photometry calculation unit 22d based on the image signal output from the imaging pixels constituting the second pixel group, and the imaging optics. The brightness of light through the systems 3 and 5 is calculated. At this time, the image processing unit 21 generates a live view image based on the image signal output from the imaging pixels constituting the third pixel group. As described above, in the live view mode, the AE process and the live view image can be displayed at high speed in parallel.

(4) Further, when the mode 3 is set for the image sensor 17, the CPU 22 uses the photometry calculation unit 22d based on the image signal output from the imaging pixels constituting the second pixel group, and the imaging optics. The brightness of light through the systems 3 and 5 is calculated. Since it did in this way, AE processing can be performed at high speed in live view mode.

(5) The signal readout mode setting unit 22b selectively switches and sets mode 1, mode 2 or mode 3 according to the operating state of the camera body 1. That is, when the live view mode is set in the camera body 1 by the shooting mode setting unit 22 a, the signal readout mode setting unit 22 b sets mode 2 for the image sensor 17. When the operation detection unit 22j detects that the shutter button is half-pressed as a focus adjustment instruction operation from the user, the signal readout mode setting unit 22b sets mode 1 for the image sensor 17. Further, when the operation detection unit 22j detects that the shutter button is fully pressed as a photographing instruction operation from the user, the signal readout mode setting unit 22b sets mode 3 for the image sensor 17. Thus, by switching the signal readout mode according to the imaging sequence, an optimal signal output can be obtained from the image sensor 17.

  The embodiment and the modification described above are merely examples, and the present invention is not limited to these contents as long as the features of the invention are not impaired. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

It is a block diagram which shows the structure of the camera to which the image pick-up element by one embodiment of this invention is applied. It is a figure which shows a mode when live view mode is set. It is a figure which shows the structure of the control system in a camera main body. It is a figure which shows the correspondence of the example of pixel arrangement | positioning in an image pick-up element, and the row | line | column of the image read in each signal read-out mode. It is a figure which shows the relationship between the operation | movement of a camera main body, and the switching timing of signal reading mode.

Explanation of symbols

1: Camera body 2: Lens unit 3, 5: Shooting optical system 15: Photometric sensor 16: Liquid crystal display 17: Image sensor 21: Image processing unit 22: CPU

Claims (5)

A first pixel column having a first pixel group as a plurality of focus detection pixels; a second pixel column having a plurality of second pixel groups different from the first pixel group; the first pixel group and the first pixel group; an imaging element and a third pixel row having a plurality of different third pixel group and second pixel group,
A focus detection unit that performs phase detection based focus detection using the first signal output from the first pixel group;
A photometric unit that performs photometry using the second signal output from the second pixel group;
A display control unit that controls live view display using the third signal output from the third pixel group and the second signal output from the second pixel group;
A first mode in which focus detection by the focus detection unit, photometry by the photometry unit, and live view display by the display control unit are performed, photometry by the photometry unit, and second view that performs live view display by the display control unit A selection unit for selecting any one of the mode and a third mode for performing photometry by the photometry unit;
When the selection unit selects the first mode, first thinning control is performed so that the first pixel column, the second pixel column, and the third pixel column are selected, and the selection unit performs the first thinning control. When the second mode is selected, second thinning control is performed so that the second pixel column and the third pixel column are selected, and when the third mode is selected by the selection unit, the second pixel An image pickup apparatus comprising: a thinning control unit that performs third thinning control so that a column is selected. The imaging device according to claim 1,
When the first mode is selected by the selection unit, based on the first thinning control performed by the thinning control unit,
The focus detection unit uses an optical system based on a phase difference method using the first signals output from the plurality of focus detection pixels that are the first pixel columns of the image sensor that constitutes the first pixel group. Focus detection ,
The photometry unit detects the brightness of light through the optical system using a second signal output from a second pixel column of the image sensor that constitutes the second pixel group,
The display control unit outputs a third signal output from a third pixel column of the image sensor that constitutes the third pixel group , and a second pixel column of the image sensor that constitutes the second pixel group. An image pickup apparatus that performs live view display using the output second signal . The imaging device according to claim 1 ,
When the second mode is selected by the selection unit , based on the second thinning control performed by the thinning control unit,
The photometry unit detects the brightness of light via an optical system using a second signal output from a second pixel column of the image sensor that constitutes the second pixel group,
The display control unit outputs a third signal output from a third pixel column of the image sensor that constitutes the third pixel group , and a second pixel column of the image sensor that constitutes the second pixel group. An image pickup apparatus that performs live view display using the output second signal . The imaging device according to claim 1 ,
When the third mode is selected by the selection unit , based on the third thinning control performed by the thinning control unit,
The photometric unit detects brightness of light through an optical system using a second signal output from a second pixel column of the image sensor that constitutes the second pixel group. apparatus. In the imaging device according to any one of claims 1 to 4 ,
A live view setting unit for setting a live view mode for displaying an image on the image display unit in real time by the display control unit before shooting;
An operation detection unit that detects a focus adjustment instruction operation and a shooting instruction operation from a user;
The selection unit includes:
When the live view mode is set by the live view setting unit , the second mode is selected for the image sensor,
When the focus adjustment instruction operation is detected by the operation detection unit , the first mode is selected for the image sensor,
The imaging apparatus, wherein when the shooting instruction operation is detected by the operation detection unit , the third mode is selected for the imaging device.

Images