JP2010268108A - Imaging device and display control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for an imaging device that improves the convenience in an electronic finder, which can be implemented using different imaging elements. <P>SOLUTION: The imaging device includes an optical finder, a main imaging element 5, a sub imaging element 7, and an electronic finder. The optical finder guides object light passing through a photographic lens to a finder window. The main imaging element 5 receives the object light to generate an image signal. The sub imaging element 7 contains a group of pixels 7g having a photoelectric conversion area Qb smaller than a photoelectric conversion area Qa of each pixel 5g in the main imaging element 5, and receives the object light via an optical path section common to an optical path of the optical finder to generate an image signal. The electronic finder displays a preview for an object before actual imaging, based on the image signal generated sequentially with the main imaging element 5 or the sub imaging element 7. The imaging device switches preview display using the main imaging element 5 or the sub imaging element 7, based on brightness information on the object. Thereby, the convenience can be improved for the electronic finder. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a technique of an imaging device provided with an electronic viewfinder.

  An imaging device such as a digital single-lens reflex camera is equipped with an optical viewfinder that guides the subject light to the viewfinder window using a freely movable mirror mechanism located behind the taking optical system (shooting lens). Some cameras can determine the composition of the subject (framing).

  In such an imaging device, subject light is received by an imaging element for image recording (for recording image acquisition) in a state where the mirror mechanism is retracted, and is sequentially generated by the imaging element. Some cameras have an electronic viewfinder function that allows live view display before actual photographing based on image data to be performed, for example, on a rear monitor. Furthermore, an image pickup device that includes an image display device for image display (only for live view display) that can receive subject light through a part of the optical path in the optical viewfinder, and realizes an electronic viewfinder function using the image pickup device. Is also known.

  On the other hand, taking into account the characteristics of the optical viewfinder, which deteriorates the visibility of the subject in dark places, in the case of a low-luminance subject, an imaging device that can automatically switch from the optical viewfinder to an electronic viewfinder that uses an image recording image sensor Has also been proposed (see, for example, Patent Document 1).

JP 2006-94133 A

  However, in the imaging device of Patent Document 1, although automatic switching between the optical finder and the electronic finder is possible, each live view using different imaging elements for image recording and image display in the electronic finder. Automatic switching of display (preview display) is not assumed, and this automatic switching may not be performed appropriately. That is, since an image pickup device for image display is generally smaller than that for image recording, it is difficult to perform appropriate live view display on a low-luminance subject with relatively low sensitivity. In order to satisfactorily display such a low-luminance subject in live view, it is preferable to automatically switch from an image display image sensor to image recording, but this operation is not provided with an image display image sensor. This is not possible with the imaging device of Patent Document 1. With this, the convenience of the electronic viewfinder cannot be improved.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique of an imaging apparatus that can improve the convenience of an electronic viewfinder that can be realized using different imaging elements.

  A first aspect of the present invention is an imaging apparatus, and includes an optical finder unit that guides subject light that has passed through a photographing optical system to a finder window along a predetermined optical path, and performs photoelectric conversion by receiving the subject light. A plurality of first pixels each having a photoelectric conversion region, and a plurality of first imaging elements each capable of generating an image signal related to a subject, and a plurality of photoelectric conversion regions each having a smaller area than the first image sensor A second imaging element having a second pixel and capable of receiving the subject light and generating the image signal through an optical path section common to the predetermined optical path; and the first imaging element or the second imaging element. Based on sequentially generated image signals, an electronic finder means for performing a preview display of a subject by a predetermined display means before the main photographing, and a luminance information acquisition means for acquiring luminance information related to the subject, The electronic finder means switches between the first preview display using the first image sensor and the second preview display using the second image sensor based on the brightness information acquired by the brightness information acquisition means. Display control means.

  According to a second aspect of the present invention, there is provided an imaging apparatus, comprising: an optical finder unit that guides subject light that has passed through a photographing optical system to a finder window along a predetermined optical path; and a first pixel having a predetermined number of pixels. A first image sensor that can receive the subject light and generate an image signal related to the subject, and a second pixel having a smaller number of pixels than the predetermined number of pixels, and an optical path section that is common to the predetermined optical path A second image sensor capable of receiving the subject light and generating the image signal, and a preview of the object before the main photographing based on the image signal sequentially generated by the first image sensor or the second image sensor. Electronic finder means for performing display by predetermined display means, and luminance information acquisition means for acquiring luminance information related to the subject, wherein the electronic finder means is luminance information acquired by the luminance information acquisition means Based on Can have a display control means for switching performs the second preview display using the first preview display and the second imaging device using the first image sensor.

  According to the present invention, an image signal related to a subject having a plurality of first pixels each having a photoelectric conversion region that receives light of the subject passing through the photographing optical system and performs photoelectric conversion based on luminance information related to the subject. Common to the optical path of the optical viewfinder means, which has a plurality of second pixels each having a photoelectric conversion region having a smaller area than that of the first image sensor. Switching to the second preview display using the second imaging element capable of receiving subject light through the optical path section and generating an image signal is performed. As a result, it is possible to improve the convenience of the electronic viewfinder that can be realized by using different imaging devices.

  In addition, according to the present invention, the first signal that has the first pixel of the predetermined number of pixels and receives the subject light that has passed through the photographing optical system based on the luminance information about the subject and can generate the image signal related to the subject. The first preview display using the image sensor and the second pixel having a smaller number of pixels than the predetermined number of pixels can be used to receive subject light and generate an image signal through an optical path section common to the optical path of the optical viewfinder means. Switching to the second preview display using the second image sensor. As a result, it is possible to improve the convenience of the electronic viewfinder that can be realized by using different imaging devices.

It is a front view showing the appearance composition of the imaging device concerning the embodiment of the present invention. It is a rear view which shows the external appearance structure of an imaging device. It is a block diagram which shows the function structure of an imaging device. It is sectional drawing which shows the composition determination operation | movement using OVF. It is sectional drawing which shows the composition determination operation | movement using EVF. It is sectional drawing which shows the state at the time of exposure operation | movement of the main image pick-up element. It is a conceptual diagram for demonstrating the difference between a main image sensor and a sub image sensor. 3 is a flowchart showing a basic operation of the imaging apparatus 1. It is a flowchart which shows the operation | movement of the live view display by a main image pick-up element. It is a flowchart which shows the operation | movement of the live view display by a sub image pick-up element.

<Embodiment>
[Configuration of main part of imaging device]
1 and 2 are diagrams showing an external configuration of an imaging apparatus 1 according to the embodiment of the present invention. Here, FIG. 1 is a front external view of the image pickup apparatus 1, and FIG. 2 is a rear external view of the image pickup apparatus 1. This imaging device 1 is configured as a lens interchangeable single-lens reflex digital camera.

  As shown in FIG. 1, the imaging device 1 includes a camera body (camera body) 2. An interchangeable photographic lens unit (interchangeable lens) 3 can be attached to and detached from the camera body 2.

  The photographic lens unit 3 mainly includes a lens barrel 36, a lens group 37 (see FIG. 3) provided in the lens barrel 36, a diaphragm, and the like. The lens group 37 serving as a photographing optical system includes a focus lens that changes a focal position by moving in the optical axis direction.

  The camera body 2 includes an annular mount Mt to which the photographing lens unit 3 is attached at the front center, and an attach / detach button 89 for attaching / detaching the photographing lens unit 3 near the annular mount Mt. Yes.

  Further, the camera body 2 is provided with a mode setting dial 82 in the upper left part of the front surface and a control value setting dial 86 in the upper right part of the front surface. By operating the mode setting dial 82, various camera modes (such as various shooting modes (people shooting mode, landscape shooting mode, full-auto shooting mode, etc.), playback modes for playing back captured images, and between external devices It is possible to perform a setting operation (switching operation) including a communication mode for performing data communication. Further, by operating the control value setting dial 86, it is possible to set control values in various shooting modes.

  Further, the camera body 2 includes a grip portion 14 for a photographer to hold at the left end of the front. A release button 11 for instructing the start of exposure is provided on the upper surface of the grip part 14, and a battery storage room and a card storage room are provided inside the grip part 14. In the battery compartment, a secondary battery such as a nickel metal hydride battery or a primary battery such as an alkaline battery is housed as a power source for the camera, and a memory card for recording image data of a photographed image in the card compartment. 90 (refer FIG. 3) is accommodated so that attachment or detachment is possible.

  The release button 11 is a two-stage detection button that can detect two states, a half-pressed state (S1 state) and a fully-pressed state (S2 state). When the release button 11 is half-pressed to enter the S1 state, a preparation operation (for example, an AF control operation and an AE control operation) for acquiring a recording still image (main captured image) related to the subject is performed. When the release button 11 is further pushed into the S2 state, an exposure operation related to a subject image (light image of the subject is performed using the imaging device 5 (described later) using the imaging element 5 (described later), and the exposure operation is performed. A series of operations for applying predetermined image processing to the obtained image signal is performed.

  In FIG. 2, a finder window (eyepiece window) 10 is provided at the upper center of the back surface of the camera body 2. The photographer can determine the composition by viewing the viewfinder window 10 and visually recognizing the light image of the subject guided from the photographing lens unit 3. That is, it is possible to determine the composition using the optical finder 17 (see FIG. 4) (details will be given later).

  In FIG. 2, a rear monitor 12 is provided in the approximate center of the rear surface of the camera body 2. The rear monitor 12 is configured, for example, as a color liquid crystal display (LCD), and displays a menu screen for setting shooting conditions and the like, and plays back and displays the shot image recorded in the memory card 90 in the playback mode. Can do. In addition, when the operator selects composition determination based on live view display (electronic viewfinder) instead of composition determination based on the optical viewfinder, the rear monitor 12 includes a plurality of time-series acquired by the image sensor 7 (described later). An image (that is, a moving image) is displayed as a live view image.

  A main switch 81 is provided at the upper left of the rear monitor 12. The main switch 81 is a two-point slide switch. When the contact is set to the left “OFF” position, the power is turned off. When the contact is set to the right “ON” position, the power is turned on.

  A direction selection key 84 is provided on the right side of the rear monitor 12. This direction selection key 84 has a circular operation button, and it is possible to detect a pressing operation in four directions of up, down, left and right, and a pressing operation in four directions of upper right, upper left, lower right and lower left on this operation button. It has become. In addition, the direction selection key 84 is configured to detect a pressing operation of a push button at the center, in addition to the pressing operations in the eight directions.

  A setting button group 83 including a plurality of buttons for setting a menu screen, deleting an image, and the like is provided on the left side of the rear monitor 12.

  Next, an overview of functions of the imaging apparatus 1 will be described with reference to FIG. FIG. 3 is a block diagram illustrating a functional configuration of the imaging apparatus 1.

  As shown in FIG. 3, the imaging apparatus 1 includes an operation unit 80, an overall control unit 101, a focus control unit 121, a mirror control unit 122, a shutter control unit 123, a timing control circuit 124, a digital signal processing circuit 50, and the like. .

  The operation unit 80 includes various buttons and switches including the release button 11 (see FIG. 1). In response to an operator's input operation on the operation unit 80, the overall control unit 101 implements various operations.

  The overall control unit 101 is configured as a microcomputer, and mainly includes a ROM including a CPU, a RAM, and an EEPROM 101a. Note that various adjustment values and setting values of the imaging apparatus 1 are stored in the EEPROM 101a which is a nonvolatile memory.

  The overall control unit 101 implements various functions in software by reading a program stored in the ROM and executing the program by the CPU. For example, the overall control unit 101 performs a focus control operation for controlling the position of the focus lens in cooperation with the AF module 20, the focus control unit 121, and the like. The overall control unit 101 implements an AF operation using the focus control unit 121 according to the focus state of the subject detected by the AF module 20. Note that the AF module 20 can detect the in-focus state of the subject by using the light entering through the mirror mechanism 6 by a phase-difference in-focus state detection method (phase difference AF).

  The overall control unit 101 includes a display control unit 102 and a luminance detection unit 103 that are implemented as software. The display control unit 102 realizes an electronic viewfinder that performs live view display (preview display) of a subject on the rear monitor 12 before actual photographing based on image signals sequentially generated by the image sensor 5 or the image sensor 7. On the other hand, the luminance detection unit 103 acquires information on luminance values related to the subject based on image signals sequentially generated by the image sensor 5 or the image sensor 7 during live view display. In the luminance detection unit 103, for example, an average value of each pixel data in a predetermined image region (for example, the entire region or the central portion) in the live view image is calculated as a luminance value (BV value).

  The focus control unit 121 moves a focus lens included in the lens group 37 of the photographing lens unit 3 by generating a control signal based on a signal input from the overall control unit 101 and driving the motor M1. The position of the focus lens is detected by the lens position detection unit 39 of the photographing lens unit 3, and data indicating the position of the focus lens is sent to the overall control unit 101. As described above, the focus control unit 121, the overall control unit 101, and the like control the movement of the focus lens in the optical axis direction.

  The mirror control unit 122 controls state switching between a state in which the mirror mechanism 6 is retracted from the optical path (mirror up state) and a state in which the mirror mechanism 6 blocks the optical path (mirror down state). The mirror control unit 122 switches between the mirror up state and the mirror down state by generating a control signal based on the signal input from the overall control unit 101 and driving the motor M2.

  The shutter control unit 123 controls the opening and closing of the shutter 4 by generating a control signal based on the signal input from the overall control unit 101 and driving the motor M3.

  The timing control circuit 124 performs timing control for the image sensor 5 and the like.

  The imaging element 5 is configured as a CMOS sensor, for example, and converts a light image of a subject into an electrical signal by a photoelectric conversion action, and generates an image signal (recording image signal) related to the actual captured image. In other words, the image sensor (first image sensor) 5 has a plurality of pixels each having a photoelectric conversion region Qa (see FIG. 7) that receives subject light that has passed through the photographing lens unit 3 and performs photoelectric conversion. Therefore, it is possible to generate an image signal related to the subject. The image pickup device 5 is also expressed as an image pickup device for image recording (recorded image acquisition).

  In response to the drive control signals (accumulation start signal and accumulation end signal) input from the timing control circuit 124, the image sensor 5 performs exposure (charge accumulation by photoelectric conversion) of the subject image formed on the light receiving surface. Then, an image signal related to the subject image is generated. The image sensor 5 outputs the image signal to a signal processing unit 51 including an AGC (Auto Gain Control) circuit in response to the read control signal input from the timing control circuit 124. The timing signal (synchronization signal) from the timing control circuit 124 is also input to the signal processing unit 51 and the A / D (analog / digital) conversion circuit 52.

  The image signal acquired by the image sensor 5 is subjected to predetermined analog signal processing (for example, processing for increasing gain by an AGC circuit to optimize the luminance level of the image) in the signal processing unit 51, and the analog signal processing. The subsequent image signal is converted into digital image data (image data) by the A / D conversion circuit 52. This image data is input to the digital signal processing circuit 50.

  The digital signal processing circuit 50 performs digital signal processing on the image data input from the A / D conversion circuit 52 to generate image data related to the captured image. The digital signal processing circuit 50 includes a black level correction circuit 53, a white balance (WB) circuit 54, a γ correction circuit 55, and an image memory 56.

  The black level correction circuit 53 corrects the black level of each pixel data constituting the image data output from the A / D conversion circuit 52 to a reference black level. The WB circuit 54 performs white balance adjustment of the image. The γ correction circuit 55 performs gradation conversion of the captured image. The image memory 56 is a high-speed accessible image memory for temporarily storing generated image data, and has a capacity capable of storing image data for a plurality of frames.

  At the time of actual photographing, the image data temporarily stored in the image memory 56 is appropriately subjected to image processing (such as compression processing) in the overall control unit 101 and then stored in the memory card 90 via the card I / F 132.

  Further, the image data temporarily stored in the image memory 56 is appropriately transferred to the VRAM 131 by the overall control unit 101, and an image based on the image data is displayed on the rear monitor 12. Thereby, confirmation display (after view) for confirming the captured image, reproduction display for reproducing the captured image, and the like are realized.

  The imaging apparatus 1 further includes an imaging element 7 (see also FIG. 4) that is different from the imaging element 5. The image sensor 7 serves as an image sensor dedicated to so-called live view image acquisition (moving image acquisition). The image sensor 7 also has the same configuration as the image sensor 5. However, the image sensor 7 only needs to have a resolution for generating an image signal (moving image) for live view, and usually has a smaller number of pixels than the image sensor 5 and has low power consumption. Yes.

  The same signal processing as that of the image signal acquired by the image sensor 5 is performed on the image signal acquired by the image sensor 7. That is, the image signal acquired by the image sensor 7 is subjected to predetermined processing by the signal processing unit 51, converted into digital data by the A / D conversion circuit 52, and then subjected to predetermined image processing by the digital signal processing circuit 50. And stored in the image memory 56.

  The time series image data acquired by the image sensor 7 and stored in the image memory 56 is sequentially transferred to the VRAM 131 as appropriate by the overall control unit 101, and an image based on the time series image data is displayed on the rear monitor 12. Is done. As a result, display of a moving image mode (live view display) for composition determination is realized.

  Furthermore, the imaging apparatus 1 has a communication I / F 133 and can perform data communication with a device (for example, a personal computer) to which the interface 133 is connected.

  The imaging device 1 also includes a flash 41, a flash control circuit 42, and an AF auxiliary light emitting unit 43. The flash 41 is a light source used when the luminance of the subject is insufficient. Whether or not the flash is turned on and the lighting time are controlled by the flash control circuit 42, the overall control unit 101, and the like. The AF auxiliary light emitting unit 43 is an auxiliary light source for AF. The presence or absence of lighting of the AF auxiliary light emitting unit 43 and the lighting time are controlled by the overall control unit 101 and the like.

[Shooting Operation of Imaging Device 1]
Next, a photographing operation including a composition determining operation in the imaging apparatus 1 will be described. As described above, in the imaging apparatus 1, it is possible to perform composition determination (framing) using an optical viewfinder (also referred to as an optical viewfinder (OVF)) configured by a viewfinder optical system or the like, and the rear monitor 12. It is also possible to determine the composition using the live view image displayed on the screen. Here, the finder function realized by using the image pickup device 7 and the rear monitor 12 is called an electronic view finder (EVF) because it visualizes the optical image of the subject after converting it into electronic data. . The imaging apparatus 1 selects a mode for realizing an optical viewfinder (hereinafter also referred to as “OVF mode”) and a mode for realizing an electronic viewfinder (electronic viewfinder) (hereinafter also referred to as “EVF mode”). A changeover switch 85 (FIG. 2) is provided.

  4 and 5 are cross-sectional views of the imaging device 1. FIG. 4 shows a composition determination operation using the OVF, and FIG. 5 shows a composition determination operation using the EVF. FIG. 6 is a cross-sectional view showing a state during the exposure operation of the image sensor 5.

  As shown in FIG. 4 and the like, a mirror mechanism 6 is provided on the optical path (imaging optical path) from the imaging lens unit 3 to the image sensor 5. The mirror mechanism 6 has a main mirror 61 (main reflection surface) that reflects light from the photographing optical system upward. For example, a part or all of the main mirror 61 is configured as a half mirror, and transmits a part of light from the photographing optical system. The mirror mechanism 6 also includes a sub mirror 62 (sub reflective surface) that reflects light transmitted through the main mirror 61 downward. The light reflected downward by the sub mirror 62 is guided to the AF module 20 and is incident thereon, and is used for the phase difference type AF operation.

  Until the release button 11 is fully pressed S2 in the photographing mode, in other words, when determining the composition, the mirror mechanism 6 is arranged so as to be in the mirror-down state (see FIGS. 4 and 5). At this time, the subject image from the photographic lens unit 3 is reflected upward by the main mirror 61 and enters the pentamirror 65 as an observation light beam. The pentamirror 65 has a plurality of mirrors (reflection surfaces) and has a function of adjusting the orientation of the subject image. Further, the path of the observation light beam after entering the pentamirror 65 differs depending on which of the above-described two methods (that is, the OVF method and the EVF method) is used for composition determination. This will be described later. The operator can determine the composition according to the selected desired method.

  On the other hand, when the release button 11 is fully pressed S2, the mirror mechanism 6 is driven so as to be in the mirror up state, and an exposure operation is started (see FIG. 6). The operation when acquiring a still image for recording (also referred to as a main image) related to the subject (that is, the operation during exposure) is common to the composition determination by both the above-described methods (that is, the OVF method and the EVF method).

  Specifically, as shown in FIG. 6, at the time of exposure, the mirror mechanism 6 is retracted from the photographing optical path. Specifically, the main mirror 61 and the sub mirror 62 are retracted upward so as not to block the light (subject image) from the photographic optical system, and the light from the photographic lens unit 3 is synchronized with the opening timing of the shutter 4. Reach 5 The imaging element 5 generates an image signal of the subject based on the received light flux by photoelectric conversion. As described above, the light from the subject is guided to the image sensor 5 through the photographing lens unit 3, thereby obtaining a photographed image (photographed image data) relating to the subject.

  Next, each of the above-described two operations when determining the composition will be described.

  First, the composition determination operation of the OVF method will be described.

  As shown in FIG. 4, when the main mirror 61 and the sub mirror 62 of the mirror mechanism 6 are arranged on the optical path of the subject image from the photographing lens unit 3, the subject image is the main mirror 61, the pentamirror 65, and the eyepiece 67. To the viewfinder window 10. Thus, in the optical viewfinder 17 including the main mirror 61, the pentamirror 65, and the eyepiece lens 67, the observation light flux that is subject light that has passed through the photographing optical system and is reflected by the main mirror 61 is It is possible to guide to the finder window 10 along the optical path PA and display the subject in the finder window 10.

  Specifically, the light from the photographic lens unit 3 is reflected by the main mirror 61, changes its path upward, forms an image on the focusing screen 63, and passes through the focusing screen 63. Thereafter, the light passing through the focusing screen 63 is further changed in its path by the pentamirror 65, and then travels through the eyepiece lens 67 to the finder window 10 (see the optical path PA in FIG. 4). In this way, the subject image that has passed through the finder window 10 reaches the eye of the photographer (observer) and is visually recognized. That is, the photographer can confirm the subject image by looking through the finder window 10.

  Here, the pentamirror 65 includes two mirrors (dach mirrors) 65a and 65b formed in a triangular roof shape, a surface 65c fixed to the roof mirrors (dach surfaces) 65a and 65b, and an actuator (not shown). And a mirror (hereinafter also referred to as “movable mirror”) 65e that can be rotationally driven around the axis AX1 by a motor (for example, a motor). Further, the two mirrors 65a and 65b having a triangular roof shape are formed as an integral part 65d by plastic molding. The light reflected by the main mirror 61 and whose path has been changed upward is reflected by the roof mirrors 65a and 65b and reversed left and right, and further reflected by the movable mirror 65e so that the light is reversed vertically and is reflected by the photographer's eyes. To reach. In this way, the left and right and up and down light images in the interchangeable lens 3 are further reversed by the pentamirror 65 in the left and right and up and down directions. As a result, the photographer can observe the subject image in the optical viewfinder 17 with the top, bottom, left, and right being the same as the actual subject.

  Further, the light that has passed through the main mirror 61 is reflected by the sub mirror 62, changes its path downward, and enters the AF module 20. The AF module 20, the focus control unit 121, and the like implement an AF operation using light that has entered through the main mirror 61 and the sub mirror 62.

  Next, the composition determination operation by the EVF method will be described.

  Also in this case, as shown in FIG. 5, the main mirror 61 and the sub mirror 62 of the mirror mechanism 6 are arranged on the optical path of the subject image from the photographing lens unit 3. Then, the light from the photographic lens unit 3 is reflected by the main mirror 61, changes the course upward, forms an image on the focusing screen 63, and passes through the focusing screen 63.

  However, in the composition determination operation by the EVF method, the light passing through the focusing screen 63 is further changed in its path by the pentamirror 65, and then passes through the imaging lens 69 (imaging optical system) to obtain the image sensor 7. The image is re-imaged on the imaging surface (see the optical path PB in FIG. 5). The light reflected by the main mirror 61 and whose path has been changed upwards is reflected by the roof mirrors 65a and 65b and reversed left and right, and further reflected by the mirror 65e so that it is also vertically reversed. The image is inverted up and down and left and right at 69 and reaches the image sensor 7.

  More specifically, as can be seen from comparison with FIG. 4, the angle of the mirror 65 e (installation angle with respect to the camera body 2) is changed in FIG. 5. Specifically, the mirror 65e is rotated from the state of FIG. 4 by a predetermined angle α around the axis AX1 on the lower end side in the direction of the arrow AR1.

  Then, by changing the angle of the mirror 65e, the reflection angle of the light (observation light beam) reflected by the mirror 65e is changed, and the traveling path of the reflected light by the mirror 65e is changed. Specifically, compared with the state of FIG. 4, the incident angle θ1 to the mirror 65e is relatively small, and the reflection angle θ2 is also relatively small. As a result, the reflected light of the mirror 65e changes its path upward from the optical path toward the eyepiece lens 67 to the optical path near the roof mirrors 65a and 65b, passes through the imaging lens 69, and reaches the image sensor 7. In other words, the image sensor (second image sensor) 7 can receive the subject light through the optical path PB having the optical path section common to the optical path PA of the optical finder 17 and generate an image signal. The imaging lens 69 and the image sensor 7 are disposed above the eyepiece lens 67, and are disposed at positions that do not block the light beam traveling from the mirror 65e to the eyepiece lens 67 during OVF. .

  Further, the path of the light beam reflected by the mirror 65e is changed by an angle β (= 2 × α) that is twice as large as the change angle α of the mirror 65e. In other words, in order to change the traveling angle of the reflected light path by the angle β, the rotation angle of the mirror 65e may be an angle α that is half the angle β. That is, it is possible to change the path of the reflected light of the mirror 65e relatively large with a relatively small rotation angle of the mirror 65e. Further, since the mirror 65e and the image pickup device 7 are disposed relatively apart from each other, the eyepiece lens 67 disposed by separating the two reflected lights from the mirror 65e apart from each other only by changing the rotation angle of the mirror 65e small. Further, it is possible to reliably lead to the image sensor 7. That is, by changing the rotation angle of the mirror 65e to be small, the light beam reflected by the mirror 65e can be selectively advanced to two optical paths. Therefore, an increase in space due to the rotation of the mirror 65e is minimized.

  The image sensor 7 generates a live view image based on the subject image reflected by the mirror 65e, passing through the imaging lens 69, and reaching the image sensor 7. Specifically, a plurality of images are sequentially generated at a minute time interval (for example, 1/60 seconds). The acquired time-series images are sequentially displayed on the rear monitor 12. Thus, the photographer can visually recognize the moving image (live view image) displayed on the rear monitor 12 and determine the composition using the moving image.

  Also in this case, the AF operation is realized using light incident on the AF module 20 via the main mirror 61 and the sub mirror 62, as in the case of composition determination by the OVF (see FIG. 4).

  As described above, the path of the observation light beam after being reflected by the mirror 65e is the optical path PA (FIG. 4) from the mirror 65e toward the eyepiece 67 and the viewfinder window 10 by changing the reflection angle of the mirror 65e, and the mirror 65e. To the imaging lens 69 and the optical path PB (FIG. 5) toward the image sensor 7. In other words, the path of the observation light beam is reflected by the mirror 65e by the change in the reflection angle of the mirror 65e, and is reflected by the mirror 65e and reflected by the mirror 65e toward the image sensor 7. It is switched between the second optical path PB.

  Therefore, in the imaging device 1, the reflection angle of a certain reflecting surface (mirror 65e) among the plurality of mirrors 65a, 65b, 65e constituting the pentamirror 65 is changed, while the other reflecting surface (the roof mirror 65a) is changed. , 65b) are fixed. That is, the path of the observation light beam is changed by driving only one reflection surface 65e among the plurality of reflection surfaces, so that the drive portion can be reduced and the configuration can be made compact.

  In addition, in the imaging device 1, images obtained sequentially by the imaging device 5 for acquiring a recorded image in a state where the mirror mechanism 6 is retracted from the imaging optical path as shown in FIG. It is also possible to perform live view display on the rear monitor 12 based on the data. In this case, contrast focus detection (hereinafter also referred to as “contrast AF”) based on image data generated by the image sensor 5 is performed.

  That is, the imaging device 1 can perform live view display by the imaging device 5 or the imaging device 7 in the EVF mode. In the EVF mode, live view display using the image sensor 7 is set as a default.

  As described above, the imaging apparatus 1 can perform live view display using the image sensor 5 and live view display using the image sensor 7 in the EVF mode. explain.

[Separate use of live view display]
As described above, the imaging apparatus 1 can perform live view display on the rear monitor 12 using the imaging element 5 for recording image acquisition (for image recording) or the imaging element 7 dedicated for live view image acquisition (for image display). Next, the difference in configuration between the image sensor (hereinafter also referred to as “main image sensor”) 5 and the image sensor (hereinafter also referred to as “sub image sensor”) 7 will be described.

  FIG. 7 is a conceptual diagram for explaining the difference between the main image sensor 5 and the sub image sensor 7. FIG. 7A and FIG. 7B show planar images of the main image sensor 5 and the sub image sensor 7 and represent a smaller number of pixels than actual.

  The sub image sensor 7 provided only for obtaining the live view image is not required to have a higher resolution than the main image sensor 5 for image recording, and it is preferable to reduce the occupied space. Therefore, the sub image sensor 7 is smaller than the main image sensor 5, and the following structural differences occur.

(1) Difference in Pixel Pitch The pixel pitch Pb related to the pixel 7g of the sub image sensor 7 is smaller than the pixel pitch Pa related to the pixel 5g of the main image sensor 5. Along with this, the area of the photoelectric conversion region Qb (parallel oblique line portion) composed of photodiodes in the sub image sensor 7 becomes smaller than the area of the photoelectric conversion region Qa (parallel oblique line portion) in the main image sensor 5. In other words, the sub image sensor 7 has a plurality of pixels each including a photoelectric conversion region Qb having a smaller area than the main image sensor 5.

(2) Difference in Number of Pixels Since the sub image sensor 7 allows lower resolution than the main image sensor 5, the number of pixels is smaller than that of the main image sensor 5. That is, the sub image sensor 7 is configured to include a pixel group having a smaller number of pixels than the number of pixels of the main image sensor 5.

  Due to the difference in configuration as described above, the sub imaging device 7 whose sensitivity is lower than that of the main imaging device 5 is not suitable for imaging in a dark environment, that is, imaging a low-luminance subject. Therefore, in the imaging apparatus 1 according to the present embodiment, it is determined whether or not the subject has low brightness. If the subject has low brightness, the display control unit 102 performs live view display using the main image sensor 5 from the sub image sensor 7. To automatically switch to

  Here, if the display screen is still dark even after switching to the live view display by the main image sensor 5, the display control unit 102 executes control to brighten the display screen by performing pixel addition. Specifically, when a low-brightness subject is imaged by the main image sensor 5, the AGC circuit of the signal processing unit 51 increases the gain to optimize the brightness level of the captured image. When it becomes higher, the noise of the display image becomes conspicuous. In this way, when the noise of the display image becomes significant, for example, a pixel addition process of adding four pixels is performed in the imaging device 1 so that the display screen is brightened while suppressing the noise of the display image. It should be noted that the pixel addition process uses a known (well-known) technique, and is not limited to four-pixel addition, and more pixel addition or two-pixel addition may be performed.

  Next, a specific operation of the imaging apparatus 1 that executes the proper use of the live view display as described above will be described.

[Operation of Imaging Device 1]
FIG. 8 is a flowchart showing the basic operation of the imaging apparatus 1. This operation is executed by the overall control unit 101.

  In the imaging apparatus 1 in the power-off state, it is determined whether the power is turned on by a user operation on the main switch 81 (step ST1). Here, when the power is turned on, the process proceeds to step ST2, and when the power is not turned on, the step ST1 is continued.

  In step ST <b> 2, the imaging apparatus 1 is activated in the EVF mode, that is, a mode in which live view display is performed on the rear monitor 12.

  In step ST3, it is determined whether the main image sensor 5 or the sub image sensor 7 has been designated as an image sensor for acquiring a live view image immediately before the main switch 81 is turned off. If any image sensor is designated, the process proceeds to step ST4. If any image sensor is not designated, the process proceeds to step ST5.

  In step ST4, it is determined whether the main image sensor 5 has been designated immediately before the power is turned off. If the main image sensor 5 is designated, the process proceeds to step ST6. If the sub image sensor 7 is designated instead of the main image sensor 5, the process proceeds to step ST7.

  In step ST5, since no image sensor is designated immediately before the power is turned off, the sub image sensor 7 set as a default is designated.

  In step ST6, live view display is performed by the main image sensor 5 (detailed later).

  In step ST7, live view display is performed by the sub image sensor 7 (detailed later).

  FIG. 9 is a flowchart corresponding to the above-described step ST6 and showing the live view display operation by the main image sensor 5.

  In step ST <b> 11, live view display is started on the rear monitor 12 based on the image data acquired by the main image sensor 5.

  In step ST12, the luminance detection unit 103 detects the luminance value (BV value) of the subject based on the image data acquired by the main image sensor 5.

  In step ST13, it is determined whether the BV value detected in step ST12 is equal to or less than a threshold value α (for example, BV value α = 4). If the BV value is less than or equal to the threshold value α, the process proceeds to step ST14. If the BV value is greater than the threshold value α, the process proceeds to step ST23.

  In step ST14, use of the main image sensor 5 is continued. That is, the live view display by the main image sensor 5 is continued.

  In step ST15, it is determined whether the BV value detected in step ST12 is equal to or less than a threshold value β (for example, BV value β = −1). If the BV value is less than or equal to the threshold β, the process proceeds to step ST16. If the BV value is greater than the threshold β, the process proceeds to step ST17.

  In step ST <b> 16, the pixel addition process described above is performed to increase the luminance level of the image acquired by the main image sensor 5. That is, excessive gain increase is performed in the AGC circuit of the signal processing unit 51, and noise is conspicuous in the rear monitor 12, so that, for example, the display screen is brightened by adding four pixels.

  In step ST17, it is determined whether the release button 11 is half-pressed. If it is half-pressed, the process proceeds to step ST18. If it is not half-pressed, step ST17 is continued.

  In step ST18, contrast AF is performed. In other words, the contrast AF is performed based on the image data acquired by the main image sensor 5 to perform focusing.

  In step ST19, it is determined whether the release button 11 is fully pressed. Here, if it is fully pressed, the process proceeds to step ST20. If it is not fully pressed, the process proceeds to step ST22.

  In step ST20, the main image sensor 5 is exposed (main exposure) to perform a photographing operation. Specifically, a subject is imaged, an image signal is generated by the main image sensor 5, and signal processing and image processing are performed on the image signal by the signal processing unit 51 and the digital signal processing circuit 50, and recording is performed. Image data is created.

  In step ST21, the captured image data created in step ST20 is stored in the memory card 90.

  In step ST22, it is determined whether the release button 11 is half pressed. Here, when it is in the half-pressed state, the process returns to step ST19. When it is not in the half-pressed state, that is, when the half-press is released, the process returns to step ST12.

  In step ST23, the sub image pickup device 7 is switched. That is, since the subject has a relatively high luminance, switching from the main image sensor 5 being used as an image sensor for live view display to the sub image sensor 7 is performed. In other words, when the luminance value detected by the luminance detecting unit 103 is larger than the threshold (first threshold) α during live view display (preview display) using the main image sensor 5. The display is switched to the live view display using the sub image sensor 7 having lower power consumption than the main image sensor 5. As a result, power required for live view display can be reduced, and power saving can be achieved.

  FIG. 10 is a flowchart corresponding to the above-described step ST7 and showing the live view display operation by the sub image sensor 7.

  In step ST31, live view display is started on the rear monitor 12 based on the image data acquired by the sub image sensor 7.

  In step ST32, the luminance detection unit 103 detects the luminance value (BV value) of the subject based on the image data acquired by the sub image sensor 7.

  In step ST33, it is determined whether the BV value detected in step ST32 is greater than or equal to a threshold value γ (for example, BV value γ = 2). If the BV value is greater than or equal to the threshold γ, the process proceeds to step ST34. If the BV value is smaller than the threshold γ, the process proceeds to step ST41.

  In step ST34, use of the sub image sensor 7 is continued. That is, live view display is continuously executed by the sub image sensor 7.

  In step ST35, it is determined whether the release button 11 is half-pressed. If half-pressed, the process proceeds to step ST36. If not half-pressed, step ST35 is continued.

  In step ST36, phase difference AF is performed. That is, focus detection is performed by performing phase difference detection type focus detection based on the output from the AF module 20.

  In step ST37, it is determined whether the release button 11 has been fully pressed. Here, when it is fully pressed, the process proceeds to step ST38, and when it is not fully pressed, the process proceeds to step ST40.

  In step ST38, as shown in FIG. 6, the mirror mechanism 6 is retracted from the photographing optical path, and the main image sensor 5 is exposed (main exposure) to perform a photographing operation. Specifically, a subject is imaged, an image signal is generated by the main image sensor 5, and signal processing and image processing are performed on the image signal by the signal processing unit 51 and the digital signal processing circuit 50, and recording is performed. Image data is created.

  In step ST39, the captured image data created in step ST38 is stored in the memory card 90.

  In step ST40, it is determined whether the release button 11 is half pressed. Here, when it is in the half-pressed state, the process returns to step ST37, and when it is not in the half-pressed state, that is, when the half-press is released, the process returns to step ST32.

  In step ST41, the main image pickup device 5 is switched. That is, since the subject has a low luminance, switching from the sub image sensor 7 being used as an image sensor for live view display to the main image sensor 5 is performed. In other words, when the luminance value detected by the luminance detection unit 103 is smaller than the threshold (second threshold) γ during live view display (preview display) using the sub image sensor 7. The display is switched to the live view display using the main image sensor 5.

  With the operation of the imaging device 1 described above, switching between the main imaging device 5 and the sub imaging device 7 is performed using the threshold values α and γ related to the BV value. The threshold values α and γ are described above. For example, it is preferable to provide hysteresis by setting the threshold value α = BV4 and a smaller threshold value γ = BV2, that is, by setting α> γ. Thus, frequent switching between the main image sensor 5 and the sub image sensor 7 can be suppressed when a subject having a BV value within the range of the thresholds α to γ is displayed in live view.

  In the imaging apparatus 1 described above, when using the electronic viewfinder, live view display (first preview display) using the main image sensor 5 for image recording based on the luminance information acquired by the luminance detection unit 103, and Switching to live view display (second preview display) using the sub-image sensor 7 for image display is performed. As a result, it is possible to improve the convenience of an electronic viewfinder that can be realized by using different image sensors 5 and 7.

<Modification>
In the above embodiment, it is not essential to acquire the luminance value (BV value) relating to the subject with the main image sensor 5 and the sub image sensor 7. It is also possible to provide a photometric sensor (photometric element) that acquires the BV value of the subject using this photometric sensor. Thus, even if a photometric sensor provided at a location different from the image pickup devices 5 and 7 is used, the luminance information of the subject can be appropriately acquired.

  Regarding the threshold values α and γ in the above embodiment, it is not essential that α> γ, and α <γ or α = γ may be used.

  Although the present invention has been described in detail, the above description is illustrative in all aspects, and the present invention is not limited thereto. It is understood that countless variations that are not illustrated can be envisaged without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Imaging device 2 Camera body part 3 Shooting lens unit (interchangeable lens)
5 Image sensor (main image sensor)
6 Mirror mechanism 7 Image sensor (sub image sensor)
DESCRIPTION OF SYMBOLS 10 Finder window 12 Liquid crystal monitor 17 Optical finder 20 AF module 65 Penta mirror 101 Whole control part Pa, Pb Pixel pitch Qa, Qb Photoelectric conversion area

Claims (8)

Optical viewfinder means for guiding subject light passing through the photographing optical system to a viewfinder window along a predetermined optical path;
A first imaging element having a plurality of first pixels each having a photoelectric conversion region that receives the subject light and performs photoelectric conversion; and capable of generating an image signal related to the subject;
A plurality of second pixels each having a photoelectric conversion region having a smaller area than the first image sensor, and receiving the subject light through an optical path section common to the predetermined optical path, and generating the image signal A second image sensor,
An electronic viewfinder means for displaying a preview of the subject on a predetermined display means before the actual photographing based on image signals sequentially generated by the first image sensor or the second image sensor;
Luminance information acquisition means for acquiring luminance information relating to the subject;
With
The electronic finder means includes
Display control means for switching between a first preview display using the first image sensor and a second preview display using the second image sensor based on the brightness information acquired by the brightness information acquisition means;
An imaging apparatus having Optical viewfinder means for guiding subject light passing through the photographing optical system to a viewfinder window along a predetermined optical path;
A first imaging element having a first pixel with a predetermined number of pixels and capable of receiving the subject light and generating an image signal related to the subject;
A second imaging element having a second pixel number smaller than the predetermined number of pixels and capable of receiving the subject light and generating the image signal through an optical path section common to the predetermined optical path;
An electronic viewfinder means for displaying a preview of the subject on a predetermined display means before the actual photographing based on image signals sequentially generated by the first image sensor or the second image sensor;
Luminance information acquisition means for acquiring luminance information relating to the subject;
With
The electronic finder means includes
Display control means for switching between a first preview display using the first image sensor and a second preview display using the second image sensor based on the brightness information acquired by the brightness information acquisition means;
An imaging apparatus having The luminance information is information on luminance values related to the subject,
The display control means includes
A first switching unit that switches to the second preview display when the luminance value acquired by the luminance information acquisition unit becomes larger than a first threshold value during the first preview display;
A second switching unit that switches to the first preview display when the luminance value acquired by the luminance information acquisition unit becomes smaller than a second threshold value during the second preview display;
The imaging device according to claim 1, further comprising:   The imaging device according to claim 3, wherein the second threshold value is smaller than the first threshold value. The luminance information acquisition means includes
Means for acquiring the luminance information based on an image signal generated by the first image sensor or the second image sensor;
The imaging device according to claim 1, further comprising: The luminance information acquisition means includes
Means for receiving the subject light by a predetermined photometric sensor and acquiring the luminance information;
The imaging device according to claim 1, further comprising: A first display step of displaying a subject on the finder window by optical finder means for guiding the subject light passing through the photographing optical system to the finder window along a predetermined optical path;
A first image sensor that has a plurality of first pixels each including a photoelectric conversion region that receives the subject light and performs photoelectric conversion, and is capable of generating an image signal related to the subject, or a region area from the first image sensor A plurality of second pixels each having a small photoelectric conversion region, and sequentially receiving by the second imaging element capable of receiving the subject light and generating the image signal through an optical path section common to the predetermined optical path. A second display step of displaying the subject on the predetermined display means by an electronic finder means for performing a preview display of the subject on the predetermined display means based on the generated image signal;
A luminance information acquisition step of acquiring luminance information relating to the subject;
With
The second display step includes
A display control step for switching between a first preview display using the first image sensor and a second preview display using the second image sensor based on the luminance information acquired in the luminance information acquisition step;
A display control method. A first display step of displaying a subject on the finder window by optical finder means for guiding the subject light passing through the photographing optical system to the finder window along a predetermined optical path;
A first imaging element having a first pixel with a predetermined number of pixels and capable of receiving the subject light and generating an image signal related to the subject, or a second pixel having a number of pixels smaller than the predetermined number of pixels Based on the image signals sequentially generated by the second image sensor that can receive the subject light and generate the image signal through an optical path section that is common to the predetermined optical path, a preview display of the subject is displayed before the main photographing. A second display step of displaying the subject on the predetermined display means by an electronic finder means to be performed by the predetermined display means;
A luminance information acquisition step of acquiring luminance information relating to the subject;
With
The second display step includes
A display control step of switching between a first preview display using the first image sensor and a second preview display using the second image sensor based on the brightness information acquired by the brightness information acquisition means;
A display control method.

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