JP2012113189A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus suitably carrying out exposure control and thus capable of carrying out excellent detection of the focal state of an imaging optical system.SOLUTION: The imaging apparatus includes: focus detection means 25 for detecting the focal state based on a received light signal from a prescribed pixel in imaging elements 22 which are a plurality of pixels arranged two dimensionally; a mirror 21 conducting flux to an observation optical system 24 by reflecting and having one part of the flux transmit in the state of being inserted in an optical path; display means 271 for displaying an imaged image when the mirror 21 is in the detached state from the optical path; and exposure control means 25 for carrying out exposure control so that the signal strength of the received light signal from the pixel used for detection of the focal state is a predetermined threshold or less when the mirror 21 is in the inserted state into the optical path and carrying out exposure control so that the signal strength of the received light signal from the pixel used for display of the imaged image is suitable for displaying the imaged image when the mirror 21 is in the detached state from the optical path.

Description

  The present invention relates to an imaging apparatus.

  Conventionally, an imaging device in which an array of a plurality of focus detection pixels that generate a pair of image signals corresponding to a pair of images formed by a pair of light beams passing through a photographing optical system is mixed in the array of imaging pixels is provided. The focus of the so-called pupil division phase difference detection method that detects the focus state of the photographing optical system based on the deviation amount of the pair of image signals generated by the focus detection pixel while generating the image signal by the output of the imaging pixel An imaging device having a detection function is known (for example, see Patent Document 1). Note that in such an imaging apparatus, a captured image generated based on the output of the imaging pixel is generally displayed as a through image on a display device provided in the imaging apparatus.

JP 2009-75407 A

  However, in the above-mentioned Patent Document 1, since the exposure control of the image sensor is performed in order to properly display the captured image generated based on the output of the imaging pixel, the signal intensity of the focus detection pixel is There were cases where it became inappropriate. Specifically, when exposure control is performed so that the average exposure amount of the entire shooting screen is appropriate, for example, when the main subject is a high-luminance subject, the signal of the focus detection pixel There is a case where the intensity is saturated, which causes a problem that focus detection becomes impossible.

  The problem to be solved by the present invention is to provide an imaging apparatus capable of appropriately performing exposure control and thereby detecting the focus state of the photographing optical system satisfactorily.

  The present invention solves the above problems by the following means.

  [1] An image pickup apparatus according to a first aspect of the present invention includes an image pickup element in which a plurality of pixels that receive a light beam through a photographing optical system and output a light reception signal are arranged two-dimensionally; An observation optical system capable of visually recognizing an image by the photographing optical system, focus detection means for detecting a focus state of the photographing optical system based on a light reception signal from a predetermined pixel among the plurality of pixels, and the photographing optical In the optical path between the system and the image sensor, the optical path is reflected so that the light beam is reflected and guided to the observation optical system, and a part of the light beam is transmitted. And a display means for displaying a captured image based on light reception signals from the plurality of pixels when the mirror is detached from the optical path, and the mirror is inserted in the optical path The focus state is detected. The exposure control is performed so that the signal intensity of the light reception signal from the pixel to be used is equal to or lower than a predetermined threshold, and when the mirror is detached from the optical path, the captured image is displayed. Exposure control means for performing exposure control so that a signal intensity of a light reception signal from a pixel to be used is suitable for displaying the photographed image.

  [2] An image pickup apparatus according to a second aspect of the present invention includes an image pickup element in which a plurality of pixels that receive a light beam through a photographing optical system and output a light reception signal are arranged two-dimensionally; An observation optical system capable of visually recognizing an image by the photographing optical system, focus detection means for detecting a focus state of the photographing optical system based on a light reception signal from a predetermined pixel among the plurality of pixels, and the observation optical An eyepiece detecting means for detecting an eyepiece to the system; a display means for displaying a photographed image based on light reception signals from the plurality of pixels when an eyepiece to the observation optical system is not detected; and the observation optical system When the eyepiece is detected, exposure control is performed so that the signal intensity of the light reception signal from the pixel used for the detection of the focus state is equal to or lower than a predetermined threshold value, and the observation optical system is If no eyepiece is detected, the front Signal intensity of the received signal from the pixels used to display the captured image, such that those suitable for displaying the captured image, characterized in that it comprises an exposure control means for performing exposure control.

  [3] An image pickup apparatus according to a third aspect of the present invention includes an image pickup element in which a plurality of pixels that receive a light beam through a photographing optical system and output a light reception signal are two-dimensionally arranged; An observation optical system capable of visually recognizing an image by the photographing optical system, focus detection means for detecting a focus state of the photographing optical system based on a light reception signal from a predetermined pixel among the plurality of pixels, and the plurality of the plurality of pixels When the observation optical system is used by a user and a display unit for displaying a captured image based on a light reception signal from the pixel, the signal intensity of the light reception signal from the pixel used for detection of the focus state is In addition, when exposure control is performed so that the threshold value is equal to or less than a predetermined threshold and the display unit is used by the user, the signal intensity of the light reception signal from the pixel used for displaying the captured image is the captured image. Suitable for displaying So that things, characterized in that it comprises an exposure control means for performing exposure control.

  [4] In the imaging apparatus of the present invention, the exposure control means may be configured to set the exposure time to be equal to or less than a predetermined time when the mirror is in a state of being detached from the optical path.

  [5] In the image pickup apparatus of the present invention, the exposure control means can be configured to set the exposure time to a predetermined time or less when the eyepiece to the observation optical system is not detected.

  [6] In the imaging apparatus of the present invention, the predetermined time may be configured to be a time determined based on a frame rate when a captured image is displayed by the display means.

  [7] In the imaging apparatus of the present invention, the imaging element outputs a plurality of imaging pixels that output a signal for generating image data corresponding to an image obtained by the imaging optical system, and a plurality of imaging pixels set on the imaging surface. A plurality of focus detection pixels provided corresponding to a focus detection region and outputting a signal for detecting a focus state of the photographing optical system, and the focus detection unit includes, among the plurality of focus detection regions, Based on signals from focus detection pixels constituting one or more focus detection areas, the focus state of the imaging optical system is detected, and the display means is based on signals from the plurality of imaging pixels, It can be configured to display a captured image.

  [8] In the imaging apparatus of the present invention, the exposure control means may be configured such that signal intensity of signals from focus detection pixels constituting all focus detection areas of the plurality of focus detection areas is equal to or less than the threshold value. Further, it can be configured to perform exposure control.

  [9] In the imaging apparatus of the present invention, the focus detection pixel is provided corresponding to the photoelectric conversion unit that receives a pair of light beams that pass through a pair of pupil regions of the imaging optical system, and the photoelectric conversion unit. And the focus detection unit calculates an image shift amount of the pair of images formed by the pair of light beams on the basis of a signal from the focus detection pixel, so that the focus of the photographing optical system is calculated. It can be configured to perform state detection.

  [10] In the imaging apparatus of the present invention, the image pickup apparatus includes a storage unit that stores a plurality of signals output from the focus detection pixels in time series, and the focus detection unit includes the signals output from the focus detection pixels, The signal stored in the storage means can be integrated, and the focus state of the photographing optical system can be detected based on the integrated signal.

  According to the image pickup apparatus of the present invention, exposure control can be performed appropriately, whereby the focus state of the photographing optical system can be detected well.

FIG. 1 is a main part configuration diagram showing a single-lens reflex digital camera according to an embodiment of the present invention. FIG. 2 is a front view showing a focus detection position on the imaging surface of the imaging device shown in FIG. FIG. 3 is a front view schematically showing an array of focus detection pixels by enlarging a part III in FIG. FIG. 4A is an enlarged front view showing one of the imaging pixels of FIG. 4B is an enlarged front view showing one of the focus detection pixels in FIG. 3. FIG. 5 is a spectral sensitivity characteristic diagram showing the relative sensitivity with respect to the wavelength of each of the three imaging pixels RGB shown in FIG. FIG. 6 is a spectral sensitivity characteristic diagram showing the relative sensitivity with respect to the wavelength of the focus detection pixel 222 shown in FIG. 7A is a cross-sectional view taken along line VIIa-VIIa in FIG. 4A. 7B is a cross-sectional view taken along line VIIb-VIIb in FIG. 4B. 8 is a cross-sectional view taken along line VIII-VIII in FIG. FIG. 9 is a front view schematically showing an arrangement of pixels according to another embodiment of the present invention, and is an enlarged front view corresponding to a portion III in FIG. FIG. 10 is an enlarged front view showing the pair of focus detection pixels in FIG. FIG. 11 is a flowchart (part 1) illustrating an operation example of the camera according to the embodiment of the present invention. FIG. 12 is a flowchart (part 2) illustrating an operation example of the camera according to the embodiment of the present invention. FIG. 13 is a diagram showing an example of a scene to which the embodiment of the present invention is applied. FIGS. 14A to 14C are graphs showing the relationship between the position of the focus detection pixels constituting the focus detection areas and the signal intensity of the focus detection pixels in the scene example shown in FIG. It is. 15A to 15C show the exposure conditions of the image sensor so that the signal intensity of the focus detection pixels constituting the focus detection area is not saturated in FIGS. 14A to 14C. It is a graph which shows the signal strength of the focus detection pixel in the case of setting. FIG. 16 is a diagram for explaining the storage processing of the image signal of the focus detection pixel in the embodiment of the present invention. FIGS. 17A to 17C are graphs showing the signal intensity of the focus detection pixels when the signal intensity integration process is performed in FIGS. 15A to 15C. FIG. 18 is a graph for explaining the focus detection calculation (defocus amount calculation) procedure of the camera according to the embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a main part configuration diagram showing a single-lens reflex digital camera 1 according to an embodiment of the present invention. The single-lens reflex digital camera 1 (hereinafter simply referred to as the camera 1) of the present embodiment includes a camera body 2 and a lens barrel 3, and the camera body 2 and the lens barrel 3 are detachably coupled by a mount unit 4. Has been.

  The lens barrel 3 includes a photographic optical system 31 including a lens 311, a diaphragm 312, a zoom lens 313, and a focus lens 314. The focus lens 314 is provided to be movable along the optical axis of the light beam L1 of the lens barrel 3, and its position is adjusted by the focus lens drive motor 35. The focus lens drive motor 35 is driven based on a command signal output from a camera control CPU 25 described later and input to the focus lens drive motor 35 via the lens control CPU 32.

  The camera body 2 includes a half mirror 21 for guiding the light beam L 1 from the subject to the image sensor 22 and the optical finder (observation optical system) 24. The half mirror 21 rotates about the rotation axis O between the observation position and the photographing position of the subject. In FIG. 1, a state where the half mirror 21 is at the observation position of the subject is indicated by a solid line, and a state where the half mirror 21 is at the photographing position of the subject is indicated by a dotted line. The half mirror 21 is inserted on the optical path of the light beam L1 in the state where the subject is in the observation position, and rotates so as to be retracted from the optical path of the light beam L1 in the state where the subject is in the photographing position. Therefore, in the following description, the state where the half mirror 21 is in the observation position is also referred to as an insertion position, and the state where it is in the photographing position is also referred to as a retraction position.

  The half mirror 21 is made of, for example, parallel plane glass of about 1 mm, and a multilayer film that imparts semi-transmission of light flux is formed on the main surface on the subject side. In a state where the subject is at the observation position, a part of the light beam L2 from the subject is reflected by the half mirror 21 and guided to the optical viewfinder 24, and the remaining light beam L3 is transmitted and guided to the image sensor 22. .

  Therefore, when the half mirror 21 is at the observation position, the light beam L1 from the subject is guided to the optical finder 24 and the image sensor 22, and the subject is observed by the user via the eyepiece 243, and the focus lens 314 The focus adjustment state is detected. From this state, when the user presses the release button provided in the operation unit 28, the half mirror 21 is rotated to the photographing position, and all the luminous flux L1 from the subject is guided to the image sensor 22, and the photographed image data is stored in the memory 26. Save to.

  The optical viewfinder 24 includes a screen 241, a pentaprism 242, and an eyepiece lens 243. The screen 241 is disposed on a plane conjugate with the imaging surface of the imaging element 22 in a state where the half mirror 21 is at the observation position. As a result, the user can observe the image formed on the screen 241 through the pentaprism 242 and the eyepiece lens 243.

  The camera body 2 is provided with a camera control CPU 25. The camera control CPU 25 is electrically connected to the lens control CPU 32 through an electrical signal contact 41 provided in the mount unit 4, receives lens information from the lens control CPU 32, and receives a camera such as a defocus amount to the lens control CPU 32. Send body information. In addition, the camera control CPU 25 reads an image signal from the image sensor 22, performs predetermined information processing, and outputs it to the liquid crystal display 27 and the memory 26. The camera control CPU 25 controls the entire camera, such as correction of the image signal, detection of the focus adjustment state, aperture adjustment state, and the like of the interchangeable lens 3.

The liquid crystal display 27 includes, for example, a rear liquid crystal display element 271 provided on the rear surface of the camera body and a drive circuit 272 for driving the element. The drive circuit 272 receives an image signal sent from the camera control CPU 25, and A drive signal corresponding to the image signal is sent to the rear liquid crystal display element 271 to display the captured image.
The memory 26 can be either a removable card type memory or a built-in memory.

  The operation unit 28 is a main power switch for activating the camera 1, a shutter release button, a zoom switch for performing a zoom operation of the zoom lens 313, and a photographer for setting various operation modes of the camera 1. Input switch and observation mode selector switch. The observation mode switching switch is a switch for switching the observation mode of the subject. By operating the observation mode switching switch, an optical finder mode that uses the optical finder 24 for observing the subject image, and a rear surface for observing the subject image. It is possible to switch between the rear liquid crystal mode using the liquid crystal display element 271. In the rear liquid crystal mode, the half mirror 21 is in the retracted position, and the image signal from the image sensor 22 is transmitted to the drive circuit 272 and the rear liquid crystal display element 271 via the camera control CPU 25, and the transmitted image signal is converted into the transmitted image signal. By displaying the captured image based on the rear liquid crystal display element 271, it is possible to observe the subject image using the rear liquid crystal display element 271. On the other hand, in the optical finder mode, the half mirror 21 is set to the insertion position and the subject image is observed using the optical finder 24. Therefore, the photographed image is displayed by the rear liquid crystal display element 271. Does not.

  Next, the image sensor 22 according to the present embodiment will be described.

  FIG. 2 is a front view showing the focus detection position on the imaging surface of the image sensor 22, and FIG. 3 is a front view schematically showing the arrangement of the focus detection pixels 222 by enlarging the III part of FIG. Note that the image sensor 22 is configured by, for example, a CCD image sensor, a CMOS image sensor, or the like.

  In the imaging device 22 of the present embodiment, a plurality of imaging pixels 221 are two-dimensionally arranged on the plane of the imaging surface, and a green pixel G having a color filter that transmits a green wavelength region, and a red wavelength region. A red pixel R having a transmissive color filter and a blue pixel B having a color filter that transmits a blue wavelength region are arranged in a so-called Bayer Arrangement. That is, in four adjacent pixel groups 223 (dense square lattice arrangement), two green pixels are arranged on one diagonal line, and one red pixel and one blue pixel are arranged on the other diagonal line. The image sensor 22 is configured by repeatedly arranging the pixel group 223 on the imaging surface of the image sensor 22 in a two-dimensional manner with the Bayer array pixel group 223 as a unit.

  The unit pixel group 223 may be arranged in a dense hexagonal lattice arrangement other than the dense square lattice arrangement shown in the figure. Further, the configuration and arrangement of the color filters are not limited to this, and an arrangement of complementary color filters (green: G, yellow: Ye, magenta: Mg, cyan: Cy) can also be adopted.

  4A is an enlarged front view showing one of the imaging pixels 221, and FIG. 7A is a cross-sectional view taken along the line VIIa-VIIa in FIG. 4A. One imaging pixel 221 includes a microlens 2211, a photoelectric conversion unit 2212, and a color filter (not shown). As shown in the cross-sectional view of FIG. 7A, the photoelectric conversion unit is formed on the surface of the semiconductor circuit substrate 2213 of the imaging element 22. 2212 is built in and a microlens 2211 is formed on the surface. The photoelectric conversion unit 2212 is configured to receive an imaging light beam passing through an exit pupil (for example, F1.0) of the imaging optical system 31 by the micro lens 2211 and receives the imaging light beam IB.

  The color filter of this embodiment is provided between the microlens 2211 and the photoelectric conversion unit 2212. The spectral sensitivities of the color filters of the green pixel G, the red pixel R, and the blue pixel B are shown in FIG. It is said to be as follows.

  2 and 3, focus detection pixel rows 22a, in which focus detection pixels 222 are arranged in place of the above-described imaging pixels 221 at three positions that are symmetrical to the center of the imaging surface of the imaging element 22 and from the center. 22b and 22c are provided. As shown in FIG. 3, one focus detection pixel row is configured by arranging a plurality of focus detection pixels 222 in a horizontal row, and these form one focus detection area (hereinafter, focus detection is appropriately performed). Pixel rows 22a, 22b, and 22c are designated as focus detection areas 22a, 22b, and 22c). The focus detection pixels 222 of this example are densely arranged without providing a gap at the positions of the green pixels G and blue pixels B of the image pickup pixels 221 arranged in the Bayer array.

  Note that the positions of the focus detection pixel rows 22a, 22b, and 22c shown in FIG. 2, that is, the positions of the focus detection areas 22a, 22b, and 22c are not limited to the positions shown in the figure, and may be either one or two. It is also possible to arrange the image sensor 22 at a symmetrical position from the center of the image sensor 22.

  4B is an enlarged front view showing one of the focus detection pixels 222, and FIG. 7B is a cross-sectional view taken along line VIIb-VIIb in FIG. 4B. As shown in FIG. 4B, the focus detection pixel 222 includes a micro lens 2221 and a pair of photoelectric conversion units 2222 and 2223. As shown in the cross-sectional view of FIG. 7B, the surface of the semiconductor circuit substrate 2213 of the imaging element 22 is formed. The photoelectric conversion parts 2222 and 2223 are built in, and the micro lens 2221 is formed on the surface thereof. The pair of photoelectric conversion units 2222 and 2223 have the same size and are arranged symmetrically with respect to the optical axis of the microlens 2221. The photoelectric conversion units 2222 and 2223 are configured to receive a pair of light beams that pass through a specific exit pupil (for example, F2.8) of the photographing optical system 31 by the micro lens 2221. That is, as shown in FIG. 7B, one photoelectric conversion unit 2222 of the focus detection pixel 222 receives one light beam AB1, while the other photoelectric conversion unit 2223 of the focus detection pixel 222 is an optical axis of the micro lens 2221. In contrast, a light beam AB2 that is symmetrical with the light beam AB1 is received.

  Note that the focus detection pixel 222 is not provided with a color filter, and its spectral characteristics are a combination of the spectral characteristics of a photodiode that performs photoelectric conversion and the spectral characteristics of an infrared cut filter (not shown). . FIG. 6 shows the spectral sensitivity characteristics of the focus detection pixel 222. The relative sensitivity is a spectral sensitivity characteristic obtained by adding the sensitivity of the blue pixel B, the green pixel G, and the red pixel R of the imaging pixel 221 shown in FIG. In addition, the light wavelength region where the sensitivity appears is a region including the light wavelength regions of the sensitivity of the blue pixel B, the green pixel G, and the red pixel R of the imaging pixel 221 shown in FIG. However, it may be configured to include one of the same color filters as the imaging pixel 221, for example, a green filter.

  In addition, although the photoelectric conversion units 2222 and 2223 of the focus detection pixel 222 illustrated in FIG. 4B have a semicircular shape, the shape of the photoelectric conversion units 2222 and 2223 is not limited to this, and other shapes such as an elliptical shape, a rectangular shape, and the like. It can also be a shape or a polygonal shape.

  Here, a so-called pupil division phase difference detection method for adjusting the focus based on the output of the focus detection pixel 222 described above will be described.

  FIG. 8 is a cross-sectional view taken along the line VIII-VIII in FIG. 3, and the focus detection pixel 222-1 disposed on the photographing optical axis L and the focus detection pixel 222-2 adjacent thereto are formed by the exit pupil 34. The light beams AB1-1, AB2-1, AB2-1, AB2-2 irradiated from the distance measuring pupils 341, 342 are received. However, for other focus detection pixels, the pair of photoelectric conversion units receive a pair of light beams emitted from the pair of distance measurement pupils 341 and 342.

  Here, the exit pupil 34 is an image set at a position D in front of the microlens 2221 of the focus detection pixel 222 disposed on the planned focal plane of the interchangeable lens 3. The distance D is a value uniquely determined according to the curvature and refractive index of the microlens, the distance between the microlens and the photoelectric conversion unit, and the distance D is referred to as a distance measurement pupil distance. The distance measurement pupils 341 and 342 are images of the photoelectric conversion units 2222 and 2223 projected by the micro lens 2221 of the focus detection pixel 222.

  In the figure, the arrangement direction of the focus detection pixels 222-1 and 222-2 is coincident with the arrangement direction of the pair of distance measurement pupils 341 and 342.

  The micro lenses 2221-1 and 221-2 of the focus detection pixel 222 are disposed in the vicinity of the planned focal plane of the interchangeable lens 3, and are disposed behind the micro lenses 2221-1 disposed on the optical axis L. The shape of the pair of photoelectric conversion units 2222-1 and 22223-1 is projected on the exit pupil 34 separated by the distance measuring pupil distance D, and the projected shape forms the distance measuring pupils 341 and 342.

  Similarly, the shape of the pair of photoelectric conversion units 2222-2 and 2223-2 arranged behind the microlens 2221-2 arranged away from the optical axis L is separated by the distance measuring pupil distance D. Projected onto the exit pupil 34, the projection shape forms distance measuring pupils 341 and 342.

  That is, on the exit pupil 34 at the distance measurement pupil distance D, the projection direction of each pixel 222 is set so that the projection shapes (distance detection pupils 341 and 342) of the photoelectric conversion units 2222 and 2223 of the focus detection pixels 222 match. It has been decided.

  Note that the photoelectric conversion unit 2222-1 of the focus detection pixel 222-1 is placed on the microlens 2222-1 by one focus detection light beam AB1-1 that passes through one distance measuring pupil 341 and travels toward the microlens 2222-1. A signal corresponding to the intensity of the formed image is output. In contrast, the photoelectric conversion unit 2223-1 has an image formed on the microlens 2221-1 by the other focus detection light beam AB2-1 that passes through the other distance measuring pupil 342 and travels toward the microlens 2222-1. A signal corresponding to the intensity of the signal is output.

  Similarly, the photoelectric conversion unit 2222-2 of the focus detection pixel 222-2 passes through one distance measuring pupil 341 and is focused on the microlens 2221-2 by one focus detection light beam AB1-2 that goes to the microlens 2221-2. A signal corresponding to the intensity of the image formed is output. On the other hand, the photoelectric conversion unit 2223-2 is an image formed on the microlens 221-2 by the other focus detection light beam AB <b> 2-2 passing through the other distance measuring pupil 342 and traveling toward the microlens 221-2. A signal corresponding to the intensity of the signal is output.

  A plurality of the focus detection pixels 222 are arranged in a straight line as shown in FIG. 3, and the outputs of the pair of photoelectric conversion units 2222 and 2223 of each focus detection pixel 222 are respectively output from the distance measurement pupil 341 and the distance measurement pupil 342. Are collected into output groups corresponding to the data, the data on the intensity distribution of a pair of images formed on the focus detection pixel array by the focus detection light beams AB1 and AB2 passing through the distance measurement pupil 341 and the distance measurement pupil 342, respectively, is obtained. . By applying an image shift detection calculation process such as a correlation calculation process or a phase difference detection process to the intensity distribution data, an image shift amount by a so-called pupil division phase difference detection method can be detected.

  Then, a conversion calculation is performed on the obtained image shift amount according to the center-of-gravity interval of the pair of distance measuring pupils, thereby obtaining a current focal plane with respect to the planned focal plane (the focal point corresponding to the position of the microlens array on the planned focal plane) The deviation of the focal plane at the detection position, that is, the defocus amount can be obtained.

  Incidentally, focus detection pixels 222a and 222b shown in FIGS. 9 and 10 can be used in place of the focus detection pixels 222 of the present embodiment shown in FIGS. 3 and 4B. FIG. 9 is a front view schematically showing an arrangement of pixels according to another embodiment of the present invention, an enlarged front view corresponding to the III part of FIG. 2, and FIG. 10 is a pair of focus detection pixels of FIG. It is a front view which expands and shows.

  In the embodiment shown in FIG. 3 and FIG. 4B, the focus detection pixel 222 has a pair of photoelectric conversion units 2222 and 2223, whereas in the embodiment shown in FIG. 9 and FIG. A pixel having photoelectric conversion units 2224 and 2225 paired with the focus detection pixels 222a and 222b is used.

  A focus detection pixel 222a illustrated in FIG. 10 includes a microlens 2221 and a photoelectric conversion unit 2224, and the photoelectric conversion unit 2224 is formed on the surface of the semiconductor circuit substrate 2213 of the image sensor 22 as in the cross-sectional view illustrated in FIG. 7B. The microlens 2221 is formed on the surface. The photoelectric conversion unit 2224 is disposed on the left side of a position symmetrical with respect to the optical axis of the micro lens 2221.

  On the other hand, the focus detection pixel 222b shown in FIG. 10 also includes a microlens 2221 and a photoelectric conversion unit 2225. Like the cross-sectional view shown in FIG. A conversion unit 2225 is built, and a microlens 2221 is formed on the surface thereof. The photoelectric conversion unit 2225 is disposed on the right side of a position symmetrical to the optical axis of the micro lens 2221.

  As shown in FIG. 9, the pair of focus detection pixels 222 a and 222 b are arranged in a line on the left and right from the center of the image sensor 22, and a pair of light fluxes passing through the exit pupil of the photographing optical system 31 are converted into the pair of focus detection pixels. Light is received by the respective photoelectric conversion units 2224 and 2225 of 222a and 222b.

  As described above, even when a pair of focus detection pixels 222a and 222b configured by different pixels is used, the image shift amount by the pupil division phase difference detection method is detected based on the output results of the pair of photoelectric conversion units 2224 and 2225. can do.

  In addition to this, there is an advantage that the configuration of the output readout circuit from the pixels constituting the image sensor 22 is simplified.

  Next, an operation example of the camera according to the present embodiment will be described. 11 and 12 are flowcharts showing the operation of the camera 1 according to this embodiment.

  First, when it is confirmed in step S100 that the camera 1 is powered on, the process proceeds to step S110. In the camera 1 of the present embodiment, when the power is turned on, the imaging element 22 repeatedly receives the imaging light flux and outputs a signal at a predetermined cycle (for example, 60 frames per second). It is set.

  Next, the process proceeds to step S110. In step S110, the optical finder mode (the mode in which the optical finder 24 is used for observing the subject image) is selected via the operation unit 28, or the rear liquid crystal mode (subject image It is determined whether the mode in which the rear liquid crystal display element 271 is used for observation is selected. If the optical finder mode is selected, the process proceeds to step S120. On the other hand, if the rear liquid crystal mode is selected, the process proceeds to step S140.

  If it is determined in step S110 that the optical finder mode is selected, the process proceeds to step S120. In step S120, it is determined whether or not the half mirror 21 is at the insertion position (observation position). If the half mirror 21 is not at the insertion position, the half mirror 21 is moved to the insertion position. On the other hand, when the half mirror 21 is at the insertion position, the insertion position remains unchanged.

  Next, in step S130, the camera control CPU 25 prevents the signal intensity of the focus detection pixel rows 22a, 22b, and 22c shown in FIG. 2, that is, the focus detection pixels 222 that constitute the focus detection areas 22a, 22b, and 22c, from being saturated. Then, the exposure condition of the image sensor 22 is set.

  For example, as shown in FIG. 13, when a high-luminance subject 100a is captured in the focus detection area 22a, a medium-luminance subject 100b is captured in the focus detection area 22b, and a low-luminance subject 100c is captured in the focus detection area 22c. Depending on the exposure conditions, the signal intensities in the focus detection areas 22a, 22b, and 22c are as shown in FIGS. 14 (A) to 14 (C). Here, FIGS. 14A to 14C show the positions of the focus detection pixels 222 constituting the focus detection areas 22a, 22b, and 22c in the example of the scene shown in FIG. FIG. 14A is a graph showing the relationship with the signal intensity of 222, FIG. 14A shows the signal intensity in the focus detection area 22a capturing the high-luminance subject 100a, and FIG. 14B shows the medium-luminance subject 100b. FIG. 14C shows the signal intensity in the focus detection area 22c capturing the low-luminance subject 100c, respectively. 14A to 14C, one signal intensity of the pair of image signals of the focus detection pixel 222 is indicated by a solid line, and the other signal intensity is indicated by a broken line. .

  That is, in such a case, as shown in FIG. 14A, in the focus detection area 22a capturing the high-luminance subject 100a, the pair of signal intensities from the focus detection pixels 222 becomes the saturation signal intensity. Therefore, focus detection becomes impossible in the focus detection area 22a.

  Therefore, in this embodiment, as shown in FIGS. 15A to 15C, the signal intensity of the pair of image signals of the focus detection pixels 222 constituting the focus detection areas 22a, 22b, and 22c is not saturated. In addition, the exposure condition of the image sensor 22 is set. 14A to 14C, the positions of the focus detection pixels 222 constituting the focus detection areas 22a, 22b, and 22c when the exposure conditions are changed, and the positions of the focus detection pixels 222. FIG. 15A is a graph showing the relationship with the signal intensity, and FIG. 15A shows the signal intensity in the focus detection area 22a capturing the high-luminance subject 100a, as in FIGS. 14A to 14C. 15B shows the signal intensity in the focus detection area 22b capturing the medium luminance subject 100b, and FIG. 15C shows the signal intensity in the focus detection area 22c capturing the low luminance subject 100c. , Respectively. As shown in FIGS. 15A to 15C, the signal intensity of the pair of image signals of the focus detection pixels 222 constituting each focus detection area 22a, 22b, 22c does not reach the saturation signal intensity. By setting the exposure condition, the signal intensity of the pair of image signals from the focus detection pixel 222 reaches a predetermined saturation signal intensity in the focus detection area 22a capturing the high brightness subject 100a, and focus detection is performed. It can be effectively prevented from becoming impossible.

  An exposure condition setting method that does not saturate the signal intensity of the focus detection pixels 222 constituting the focus detection areas 22a, 22b, and 22c is not particularly limited. For example, for example, an image of each focus detection pixel 222 acquired during the previous processing. Among the signals, when the signal intensity of the image signal having the highest signal intensity is Fmax and the predetermined threshold value equal to or lower than the saturation signal intensity is Fa, the exposure amount of the image sensor 22 is the exposure amount at the time of the previous processing. In contrast, an exposure condition such that “previous exposure amount × (Fa / Fmax)” can be set. Note that the threshold Fa is set in a range of Fa = 0.5 × Fsat to 0.8 × Fsat, for example, when the saturation signal intensity is Fsat.

  In the present embodiment, the exposure amount of the image sensor 22 includes the charge accumulation time of the image pickup pixel 221 and the focus detection pixel 222 constituting the image pickup element 22 and the signals of the image pickup pixel 221 and the focus detection pixel 222 constituting the image pickup element 22. Can be controlled by adjusting the amplification gain and the aperture diameter of the diaphragm 312. Here, the charge accumulation time of the image pickup pixel 221 and the focus detection pixel 222 constituting the image pickup device 22 is set to a time shorter than the period of light reception of the image pickup light beam and signal output by the image pickup device 22. When the image sensor 22 is a CCD image sensor or a CMOS image sensor, the image pickup pixel 221 and the focus detection pixel 222 are set to have the same charge accumulation time and the same amplification gain.

  On the other hand, if the rear liquid crystal mode is selected in step S110, the process proceeds to step S140. In step S140, it is determined whether or not the half mirror 21 is at the retracted position (shooting position). If the half mirror 21 is not at the retracted position, the half mirror 21 is moved to the retracted position. On the other hand, when the half mirror 21 is in the retracted position, the retracted position remains unchanged.

  Next, in step S150, the exposure condition is set by the camera control CPU 25 so that the signal intensity of the image signal of the imaging pixel 221 becomes a value suitable for generating a display image to be displayed on the rear liquid crystal display element 271. Is done. Note that the exposure condition that provides a value suitable for generating a display image is not particularly limited. For example, the signal intensity of the image signal of the imaging pixel 221 located near the center of the imaging surface is the saturation signal intensity. The exposure condition may not be reached, or the entire image pickup surface may be a portion where the signal intensity of the image signal of the imaging pixel 221 is inappropriate (a portion where the signal strength is too weak or a portion where the saturation signal strength is reached). ) May be the exposure condition that minimizes the exposure. Furthermore, the exposure condition may be such that the average value of the signal intensity of the image signals of all the imaging pixels 221 constituting the imaging element 22 is equal to or greater than a predetermined threshold value.

  In step S150, when determining the exposure condition, the exposure amount of the image sensor 22 may be determined using the signal intensity of the image signal of the imaging pixel 221 at the time of the previous process, or the camera 1 The exposure amount of the image sensor 22 may be determined using photometric data obtained by the photometry means (not shown) provided in the image sensor, and the exposure amount of the image sensor 22 can be controlled in the same manner as in step S130 described above. it can. In step S150, the charge accumulation time of the imaging pixel 221 and the focus detection pixel 222 constituting the imaging element 22 is equal to or less than the frame rate when displaying the display image on the rear liquid crystal display element 271 in step S180 described later. Set to. The frame rate at the time of displaying a display image by the rear liquid crystal display element 271 is normally set in the same manner as the period of light reception of the imaging light flux and signal output by the imaging element 22.

  In step S <b> 160, the camera control CPU 25 reads out an image signal from the imaging pixel 221 that constitutes the imaging element 22 and a pair of image signals from the focus detection pixel 222. In step S160, the image signal and the image signal of the imaging pixel 221 and the focus detection pixel 222 when exposed under the exposure conditions set in step S130 or step S150 are read out.

  In step S170, it is determined whether the optical finder mode is selected or the rear liquid crystal mode is selected via the operation unit 28. If the optical finder mode is selected, the process proceeds to step S190. On the other hand, if the rear liquid crystal mode is selected, the process proceeds to step S180.

  In step S180, the camera control CPU 25 generates a display image to be displayed on the rear liquid crystal display element 271 based on the image signal from the imaging pixel 221 read in step S160. Then, the camera control CPU 25 transmits the generated image signal of the display image to the driving circuit 272, and the driving signal corresponding to the image signal is transmitted to the rear liquid crystal display element 271, so that the rear liquid crystal display element 271 is transmitted. Thus, the display image is displayed. When the rear liquid crystal mode is selected, the display image is displayed on the rear liquid crystal display element 271 until the release light button provided on the operation unit 28 is pressed and the imaging light flux is received. It is repeatedly executed in accordance with the signal output period.

In step S190, the image signal storage processing of each focus detection pixel 221 read in step S160 is performed. FIG. 16 is a diagram for explaining a process for storing a pair of image signals of the focus detection pixel 221 in the present embodiment. In Figure 16, at time t _n, the image signal of each focus detection pixel 221 is read as a focus detection pixel signal n, similarly, the focus detection at time t _n-1 of one period before the time t _n A scene read as a pixel signal n-1, a focus detection pixel signal n-2 at time t _n-2 , and a focus detection pixel signal n-3 at time t _n-3 is shown.

In the present embodiment, the memory 26 provided in the camera body 2 includes a first memory as an area for storing image signals of the focus detection pixels 221 constituting the image sensor 22 as shown in FIG. For example, at time t _n-3 , the focus detection pixel signal read out at time t _n−3 is stored in the first memory area in the memory 26. n-3 is stored, and the focus detection pixel signal n-4 read out from the second memory area to the eighth memory area in the memory 26 one to seven periods before the time t _n-3 ~ Focus detection pixel signal n-10 is stored. That is, in this embodiment, in addition to the image signal read at the time of the current process, the image signal read from one cycle before to seven cycles before is stored in the memory 26.

Then, as shown in FIG. 16, at time t _n−2 , which is the next cycle of time t _n−3 , focus detection read out at time t _n−2 in the first memory area in the memory 26. The pixel signal n-2 is stored, and at time tn _-3 , the focus detection pixel signal n-3 to the focus detection pixel signal n-9 respectively stored in the first memory area to the seventh memory area are respectively The focus detection pixel signal n-10 stored in the eighth memory area is deleted at time tn _-3 while moving from the second memory area to the eighth memory area.

Similarly, at time t _n−1 and time t _n , the focus detection pixel signal n−1 and the focus detection pixel signal n are stored in the first memory area and stored in the first memory area to the seventh memory area, respectively. The focus detection pixel signals stored respectively move to the second memory area to the eighth memory area, and the focus detection pixel signals stored in the eighth memory area are deleted. As described above, in the present embodiment, the image sensor 22 is configured such that the focus detection pixel signal read in the cycle and the focus detection pixel signal read in the latest seven cycles are stored in the memory 26. The image signal of each focus detection pixel 221 is stored. In FIG. 16, the memory 26 has eight areas, that is, a first memory area to an eighth memory area, as areas for storing image signals of the focus detection pixels 221 constituting the image sensor 22. However, the number is not particularly limited and can be set as appropriate.

Next, in step S200, integration processing of focus detection pixel signals stored in the first memory area to the eighth memory area in the memory 26 is performed. For example, at time t _n shown in FIG. 16, the focus detection pixel signal n stored in the first memory area and the focus detection pixel signal n−1 to focus stored in the second to eighth memory areas, respectively. Processing for integrating these signal intensities is performed using the detection pixel signal n-7.

  FIGS. 17B and 17C are graphs showing the signal intensity after the integration process. Here, FIG. 17B is a graph showing the signal intensity after the integration process is performed on the signal intensity shown in FIG. 15B, that is, the focus detection area capturing the medium luminance subject 100b. It is a graph which shows the signal strength after performing an integration process with respect to the signal strength of the image signal in 22b. Similarly, FIG. 17C is a graph showing the signal intensity after the integration process is performed on the signal intensity shown in FIG. 15C, that is, the focus detection area capturing the low-luminance subject 100c. It is a graph which shows the signal strength after performing an integration process with respect to the signal strength of the image signal in 22c.

  According to the present embodiment, in step S130, the exposure condition of the image sensor 22 is set so that the signal intensity of the focus detection pixels 222 constituting the focus detection areas 22a, 22b, and 22c is not saturated. As shown in FIG. 15B and FIG. 15C, even when the signal intensity is not suitable for focus detection, by performing such signal intensity integration processing, FIG. 17B and FIG. As shown in C), it can be suitable for focus detection.

  As shown in FIG. 15A, the signal intensity of the image signal in the focus detection area 22a capturing the high-luminance subject 100a is sufficient to perform focus detection. In such a case, the signal intensity integration process is not necessarily required, and in such a case, the signal intensity integration process is not performed (FIG. 17A). That is, in the present embodiment, it is determined whether or not the signal intensity is suitable for focus detection. As a result, if the signal intensity is not suitable for focus detection, the signal intensity integration process is performed. Do. In addition, the number of image signals (number of integrations) used when performing signal intensity integration processing is not particularly limited. For example, the signal intensity of the image signal stored in the first memory area and the focal point at this time This can be determined based on the difference from the signal strength required to perform the detection. That is, when these differences are large, a large number of image signals are used when performing signal intensity integration processing. On the contrary, when these differences are small, signal intensity integration processing is performed. It is possible to set the number of image signals used for.

  Next, proceeding to FIG. 12, in step S210 shown in FIG. 12, the camera control CPU 25 calculates the defocus amount based on the pair of image signals of the focus detection pixel 222 read in step S160. In the present embodiment, the defocus amount is calculated for each focus detection area 22a, 22b, 22c. In addition, when the signal intensity integration process is performed in step S200 described above, the defocus amount is calculated using the data after the integration process.

  Here, an example of image shift detection calculation processing (correlation calculation processing) based on the read pair of image signals will be briefly described.

  In the pair of images detected by the focus detection pixel 222, the distance measurement pupils 341 and 342 may be shielded by the aperture opening 312 of the interchangeable lens 3, and the light quantity balance may be lost. Therefore, in the present embodiment, a correlation calculation of a type capable of maintaining the image shift detection accuracy is performed with respect to the loss of light amount balance.

First, a data sequence of a pair of image signals read from the focus detection pixel sequence is A1 ₁ to A1 _M and A2 _{1 to} A2 _M (M is the number of data), and the following correlation calculation formula (the following formula (1)) is used. The correlation amount C (k) is calculated.
C (k) = Σ | A1 _n · A2 _{n + 1 + k−} A2 _{n + k} · A1 _{n + 1} | (1)

In the above formula (1), Σ operation indicates a cumulative operation (sum operation) for n, and the range of _n includes data of A1 _n , A1 _{n + 1} , A2 _{n + k} , A2 _{n + 1 + k} according to the image shift amount k. The range is limited. Further, the image shift amount k is an integer, and is a relative shift amount with the data interval of the data string as a unit.

  As shown in FIG. 18A, the calculation result of the above equation (1) shows that the correlation amount C (k) is the amount of shift with high correlation between a pair of data (k = kj = 2 in FIG. 18A). Minimal (the smaller the value, the higher the degree of correlation).

Next, a shift amount x that gives a minimum value C (x) with respect to the continuous correlation amount is obtained by using a three-point interpolation method according to the following equations (2) to (5).
x = kj + D / SLOP (2)
C (x) = C (kj) − | D | (3)
D = {C (kj-1) -C (kj + 1)} / 2 (4)
SLOP = MAX {C (kj + 1) -C (kj), C (kj-1) -C (kj)} (5)

  Then, whether or not the shift amount x calculated by the equation (2) is reliable is determined as follows.

  That is, as shown in FIG. 18B, when the degree of correlation between a pair of data is low, the value of the minimal value C (x) of the interpolated correlation amount increases. Therefore, when C (x) is equal to or greater than a predetermined threshold value, it is determined that the reliability of the calculated shift amount is low, and the calculated shift amount x is canceled.

  Or, in order to normalize C (x) with the contrast of data, when the value obtained by dividing C (x) by SLOP that is proportional to the contrast is equal to or greater than a predetermined threshold, the calculated shift amount And the calculated shift amount x is cancelled.

  Alternatively, when SLOP that is proportional to the contrast is equal to or less than a predetermined threshold, it is determined that the subject has low contrast and the reliability of the calculated shift amount is low, and the calculated shift amount x is canceled. To do.

  As shown in FIG. 18C, when the correlation between the pair of data is low and there is no drop in the correlation amount C (k) between the shift ranges kmin to kmax, the minimum value C (x) is obtained. In such a case, it is determined that the focus cannot be detected.

  The correlation calculation formula is not limited to the above formula (1), and other known correlation formulas can also be used.

When it is determined that the calculated shift amount x is reliable, the image shift amount shft is obtained by the following equation (6).
shft = PY · x (6)
In the above formula (6), PY is a detection pitch (pitch of focus detection pixels).

Finally, the defocus amount def is obtained by multiplying the image shift amount shft calculated by the above equation (6) by a predetermined conversion coefficient k.
def = k · shft (7)

  In step S220, the camera control CPU 25 sets the closest defocus amount among the defocus amounts calculated in step S210 as the focus adjustment defocus amount. In the present embodiment, the case where the closest defocus amount is set as the focus adjustment defocus amount is exemplified, but the present invention is not particularly limited. For example, the defocus amount corresponding to a specific subject is set as the focus adjustment defocus amount. The amount of focus may be used.

  Next, in step S230, the camera control CPU 25 determines whether or not the absolute value of the focus adjustment defocus amount set in step S220 is within a predetermined threshold. When the absolute value of the defocus amount for focus adjustment is within a predetermined threshold value, it is assumed that the in-focus state is achieved, and the process proceeds to step S250. On the other hand, when the absolute value of the defocus amount for focus adjustment is not within the predetermined threshold value, it is determined that the in-focus state is not achieved, and the process proceeds to step S240.

  If it is determined in step S230 that the subject is not in focus, the process proceeds to step S240. In step S230, the camera control CPU 25 sets the defocus amount for focus adjustment set in step S220 to the lens control CPU 32. Sent. Then, the lens control CPU 32 drives the focus lens 314 to the in-focus position by the focus lens drive motor 35 based on the defocus amount for focus adjustment, returns to step S110, and again in steps S110 to S230 described above. Execute the process. If the defocus amount for focus adjustment set in step S220 is not reliable, or if the defocus amount cannot be calculated in step S210, the camera control CPU 25 cannot obtain the defocus amount. Is sent to the lens control CPU 32, and the control returns to step S110 without causing the lens control CPU 32 to update the control of the focus lens drive motor 35. That is, in such a case, the driving of the focus lens 314 based on the defocus amount calculated before the previous processing is continued.

  On the other hand, if it is determined in step S230 that the subject is in focus, the process proceeds to step S250. In step S250, it is determined whether or not a release button (not shown) provided on the operation unit 28 is pressed. If the release button has been pressed, the process proceeds to step S260. If the release button has not been pressed, the process returns to step S110, and the processes of steps S110 to S230 described above are executed again.

  In step S260, it is determined whether the optical finder mode is selected or the rear liquid crystal mode is selected via the operation unit 28. If the optical finder mode is selected, the process proceeds to step S270. On the other hand, if the rear liquid crystal mode is selected, the process proceeds to step S280.

  In step S270, since it is determined in step S260 that the optical finder mode is selected, the half mirror 21 is moved to the retracted position in order to guide all the light flux L1 from the subject to the image sensor 22.

  In step S280, the exposure control of the image sensor 22 is performed by the camera control CPU 25 so as to obtain an appropriate exposure amount for photographing. Next, in step S290, the camera control CPU 25 performs the imaging pixel 221 constituting the image sensor 22. And the image signal from the focus detection pixel 222 are read out.

  Here, since the image data of the focus detection pixel 222 read in step S290 is monochrome data, in step S300, the pixel data in which the focus detection pixel 222 is located is captured around these focus detection pixels 222. Pixel interpolation is performed based on the image data of the pixel 221. Thereby, color image data at the position of the focus detection pixel 222 can be obtained.

  Finally, in step S300, the image data of the imaging pixel 221 and the interpolated image data are stored in the memory 26. At this time, the obtained image data can be thinned and displayed on the rear liquid crystal display element 271.

  The camera 1 of this embodiment operates as described above.

  In the present embodiment, as the mode for observing the subject, the optical finder mode using the optical finder 24 for observing the subject image is selected, and when the half mirror 21 is at the insertion position, the focus is set. The exposure conditions of the image sensor 22 are controlled so that the signal intensities of the pair of image signals of the focus detection pixels 222 constituting the detection areas 22a, 22b, and 22c are not saturated. Thereby, according to the present embodiment, it is possible to effectively prevent a problem that the focus detection cannot be performed because the signal intensity of the pair of image signals of the focus detection pixel 222 is saturated. The focus state of the photographing optical system can be detected satisfactorily. In particular, in the present embodiment, when the optical finder mode is selected and the half mirror 21 is set to the insertion position, the subject using the rear liquid crystal display element 271 is not observed. In such a case, the exposure condition of the image pickup device 22 is controlled so as not to be suitable for a display image to be displayed on the rear liquid crystal display element 271 as described above. Is.

  The embodiment described above is described for facilitating the understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, in the above-described embodiment, the photographer operates the operation unit 28 to switch between the optical viewfinder mode and the rear liquid crystal mode. However, the optical viewfinder is automatically and independently operated by the photographer. The mode and the rear liquid crystal mode may be switched. For example, an eyepiece detection device that detects an eyepiece to the eyepiece lens 243 when a photographer looks into the optical viewfinder 24 is provided in the vicinity of the eyepiece lens 243 constituting the optical viewfinder 24 shown in FIG. Thus, it is possible to switch to the optical finder mode when the photographer's eye is detected, and to switch to the rear liquid crystal mode when the photographer's eye is not detected. As such an eyepiece detection device, for example, a light emitting element and a light receiving element are provided, and when the photographer looks into the optical viewfinder 24, the infrared light emitted from the light emitting element is the eyeball of the photographer. A device that can detect the eyepiece by receiving the reflected light generated by the reflection by the light receiving element can be used.

  Also in this case, when the optical finder mode is selected, a pair of image signal signals of the focus detection pixels 222 constituting the focus detection areas 22a, 22b, and 22c, as in the above-described embodiment. The exposure condition of the image sensor 22 is set so as not to saturate the intensity. On the other hand, when the rear liquid crystal mode is selected, the signal of the image signal of the image pickup pixel 221 is the same as in the above-described embodiment. The exposure conditions are set so that the intensity becomes a value suitable for generating a display image to be displayed on the rear liquid crystal display element 271.

  In the above-described embodiment, when the optical finder mode is selected, the half mirror 21 is set to the insertion position, and when the rear liquid crystal mode is selected, the half mirror 21 is moved to the retracted position. However, when the rear liquid crystal mode is selected, the half mirror 21 may be left in the insertion position without being moved to the retracted position. Alternatively, in the above-described embodiment, the half mirror 21 is configured to be movable between the insertion position and the retracted position. However, for example, the half mirror 21 may be configured with a pellicle mirror and fixed at the insertion position. . With such a configuration, the moving mechanism of the half mirror 21 is not required, and thus the camera 1 can be reduced in weight and size, and the moving operation of the half mirror 21 is not required. Is possible.

  Furthermore, in the above-described embodiment, the charge accumulation time of the imaging pixel 221 and the focus detection pixel 222 constituting the imaging device 22 in the optical finder mode is equal to or less than the cycle of receiving the imaging light flux and outputting the signal by the imaging device 22. However, when the luminance is low, the charge accumulation time may be set longer than the cycle of receiving the imaging light beam and outputting the signal. In other words, the period of receiving the imaging light beam and outputting the signal may be set longer according to the charge accumulation time. In particular, in the present embodiment, when the optical finder mode is selected, the captured image is not displayed on the rear liquid crystal display element 271. Thus, the light reception period of the imaging light beam and the signal output period are as described above. Can be set longer depending on the charge accumulation time.

  In the above-described embodiment, the focus detection areas 22a, 22b, and 22c provided in the image sensor 22 are exemplified to perform focus detection at the same time. However, the photographer manually operates each focus detection area 22a, A configuration may be adopted in which a focus detection area for performing focus detection is selected from 22b and 22c, and focus detection is performed in the selected focus detection area. Furthermore, in the above-described embodiment, the configuration having the plurality of focus detection areas is exemplified in the image sensor 22, but a configuration having a single focus detection area may be used, and in this case, the above-described effects can be obtained. Of course you can play.

  Furthermore, in the above-described embodiment, the configuration in which the image sensor 22 includes the focus detection pixel 222 for pupil division type phase difference detection is illustrated, but the present invention is not particularly limited to such a configuration. The present invention can also be applied when the configuration 22 includes a focus detection pixel used for so-called contrast detection.

  Note that the imaging apparatus 1 of the present embodiment is not limited to the single-lens reflex digital camera described above, and can also be applied to a lens-integrated digital still camera and video camera. Further, the present invention can also be applied to a small camera module, a surveillance camera, a robot visual recognition device, and the like built in a mobile phone.

DESCRIPTION OF SYMBOLS 1 ... Single-lens reflex digital camera 2 ... Camera body 21 ... Half mirror 22 ... Imaging device 221 ... Imaging pixel 222, 222a, 222b ... Focus detection pixel 2221 ... Micro lens 2222-2225 ... Photoelectric conversion part 24 ... Optical finder (observation optical system) )
25 ... Camera control CPU
271: Rear liquid crystal display element 3 ... Interchangeable lens 32 ... Lens control CPU
33 ... Distance indicator 314 ... Focus lens

Claims (10)

An image pickup device in which a plurality of pixels that receive a light beam through an imaging optical system and output a light reception signal are two-dimensionally arranged;
An observation optical system capable of visually recognizing an image by the photographing optical system;
A focus detection unit that detects a focus state of the photographing optical system based on a light reception signal from a predetermined pixel among the plurality of pixels;
The optical path between the imaging optical system and the imaging device is detachably provided. When the optical path is inserted into the optical path, the optical path reflects and guides the light beam to the observation optical system. A mirror that passes through the part,
When the mirror is in a state of being detached from the optical path, display means for displaying a captured image based on light reception signals from the plurality of pixels;
When the mirror is inserted in the optical path, exposure control is performed so that the signal intensity of the light reception signal from the pixel used for detecting the focus state is equal to or lower than a predetermined threshold, and When the mirror is detached from the optical path, exposure control is performed so that the signal intensity of the light reception signal from the pixel used for displaying the captured image is suitable for displaying the captured image. An image pickup apparatus comprising: an exposure control means for performing An image pickup device in which a plurality of pixels that receive a light beam through an imaging optical system and output a light reception signal are two-dimensionally arranged;
An observation optical system capable of visually recognizing an image by the photographing optical system;
A focus detection unit that detects a focus state of the photographing optical system based on a light reception signal from a predetermined pixel among the plurality of pixels;
Eyepiece detecting means for detecting an eyepiece to the observation optical system;
Display means for displaying a photographed image based on light reception signals from the plurality of pixels when an eyepiece to the observation optical system is not detected;
When an eyepiece to the observation optical system is detected, exposure control is performed so that a signal intensity of a light reception signal from a pixel used for detection of the focus state is equal to or lower than a predetermined threshold, and When an eyepiece to the observation optical system is not detected, exposure control is performed so that a signal intensity of a light reception signal from a pixel used for displaying the photographed image is suitable for displaying the photographed image. An image pickup apparatus comprising: an exposure control unit. An image pickup device in which a plurality of pixels that receive a light beam through an imaging optical system and output a light reception signal are two-dimensionally arranged;
An observation optical system capable of visually recognizing an image by the photographing optical system;
A focus detection unit that detects a focus state of the photographing optical system based on a light reception signal from a predetermined pixel among the plurality of pixels;
Display means for displaying a captured image based on light reception signals from the plurality of pixels;
When the observation optical system is used by the user, the exposure control is performed so that the signal intensity of the light reception signal from the pixel used for detection of the focus state is equal to or lower than a predetermined threshold, and the user When a display unit is used, an exposure control unit that performs exposure control so that a signal intensity of a light reception signal from a pixel used for displaying the captured image is suitable for displaying the captured image. An imaging apparatus comprising: The imaging device according to claim 1,
The exposure apparatus is configured to set the exposure time to a predetermined time or less when the mirror is detached from the optical path. The imaging device according to claim 2,
The exposure apparatus is configured to set the exposure time to a predetermined time or less when an eyepiece to the observation optical system is not detected. In the imaging device according to claim 4 or 5,
The imaging apparatus according to claim 1, wherein the predetermined time is a time determined based on a frame rate when a captured image is displayed by the display means. In the imaging device according to any one of claims 1 to 6,
The imaging element is provided corresponding to a plurality of imaging pixels that output a signal for generating image data corresponding to an image by the imaging optical system, and a plurality of focus detection areas set on the imaging surface, A plurality of focus detection pixels for outputting a signal for detecting a focus state of the photographing optical system,
The focus detection means detects a focus state of the photographing optical system based on a signal from a focus detection pixel constituting one or more focus detection areas among the plurality of focus detection areas,
The image pickup apparatus, wherein the display means displays a captured image based on signals from the plurality of image pickup pixels. The imaging apparatus according to claim 7,
The exposure control means performs exposure control so that signal intensity of signals from focus detection pixels constituting all focus detection areas out of the plurality of focus detection areas is equal to or less than the threshold value. An imaging device. The imaging apparatus according to claim 7 or 8,
The focus detection pixel includes a photoelectric conversion unit that receives a pair of light beams that pass through a pair of pupil regions of the imaging optical system, and a microlens provided corresponding to the photoelectric conversion unit,
The focus detection unit detects a focus state of the photographing optical system by calculating an image shift amount of a pair of images formed by the pair of light beams based on a signal from the focus detection pixel. An imaging apparatus characterized by the above. In the imaging device according to any one of claims 7 to 9,
Storage means for storing a plurality of signals output from the focus detection pixels in chronological order;
The focus detection unit integrates the signal output from the focus detection pixel and the signal stored in the storage unit, and detects the focus state of the photographing optical system based on the integrated signal. An imaging device that is characterized.

Images