Imaging device and ranging device

Abstract

This imaging device is provided with an imaging element that captures an image caused by an optical system and a control unit that controls, on the basis of information pertaining to the optical system, exposure conditions of a light-receiving unit of a ranging device having: a light-emitting unit that emits light; the light-receiving unit that receives light resulting from the light emitted by the light-emitting unit and then reflected by an object; a generation unit that generates information for calculating the distance to the object on the basis of the light-receiving result of the light-receiving unit.

Description

Imaging device and distance measuring device

[0001] The present invention relates to an imaging device and a distance measuring device.

[0002] 2. Description of the Related Art There has been proposed an imaging apparatus that uses a distance measuring device that measures the distance to a subject to improve focusing accuracy and reduce focusing time (see, for example, Japanese Patent Application Laid-Open No. 2003-144998).

[0003] Japanese Patent Application Laid-Open No. 2003-29135

[0004] According to a first aspect of the disclosure, an imaging device includes an imaging element that captures an image using an optical system, a light-emitting unit that emits light, a light-receiving unit that receives light that is reflected by an object from the light-emitting unit, and a generation unit that generates information for calculating the distance to the object based on the light-receiving result of the light-receiving unit, and a control unit that controls the exposure conditions of the light-receiving unit of a distance measuring device based on information related to the optical system.

[0005] According to the second aspect of the disclosure, the distance measuring device includes an emitting unit that emits light, a light receiving unit that receives light that is reflected by an object from the light emitting unit, a generating unit that generates information for calculating the distance to the object based on the light receiving result of the light receiving unit, and a transmitting unit that transmits information of a portion of the information generated by the generating unit that corresponds to the imaging range of the imaging device to the imaging device.

[0006] The configurations of the embodiments described below may be modified as appropriate, and at least a portion of the configuration may be replaced with other components. Furthermore, components that are not particularly limited in terms of their placement may be placed in any position that can achieve their function, not limited to the placement disclosed in the embodiments.

[0007] FIG. 1 is a diagram showing the configuration of a camera system including a camera according to a first embodiment. FIG. 2 is a flowchart showing an example of processing executed by the body control unit. FIG. 3 is a flowchart showing an example of processing executed by the control unit of a distance measuring device. FIG. 4A is a diagram showing the relationship between exposure time and distance measurement results when an 18% gray chart is placed 2 m from the distance measuring device. FIG. 4B is a diagram showing the relationship between exposure time and distance measurement results when an 18% gray chart is placed 5 m from the distance measuring device. FIG. 4C is a diagram showing the relationship between the distance measurable by the distance measuring device and the exposure time of the distance measuring device. FIG. 5A is a diagram showing an example of the imaging range of a digital camera at a certain point in time. FIG. 5B is a diagram showing an example of a distance image generated based on a signal output from a light receiving unit of the distance measuring device at a certain point in time. FIG. 6 is a sequence diagram for explaining the processing shown in FIGS. 2 and 3. FIG. 7 is a flowchart showing an example of focus adjustment processing executed by the body control unit. FIG. 8 is a diagram showing the relationship between exposure time and distance measurement results when an 18% gray chart is placed 2 m from the distance measuring device. Fig. 9 is a flowchart showing an example of processing executed by the body control unit according to the second embodiment, and Fig. 10 is a sequence diagram for explaining the processing of Figs.

[0008] First Embodiment A digital camera 1 (hereinafter referred to as camera 1) as an example of an imaging device according to a first embodiment will be described below with reference to FIGS. 1 to 7. FIG.

[0009] 1 is a diagram showing the configuration of a camera system 100 including a camera 1 according to the first embodiment. The camera system 100 includes a distance measuring device 50 and the camera 1. The camera 1 includes a camera body 2 and an interchangeable lens 3. In this embodiment, the camera 1 is an interchangeable lens camera, but the camera 1 may also be configured as an integrated lens camera rather than an interchangeable lens camera.

[0010] (Range Measuring Device 50) The range finding device 50 is, for example, a range finding device that uses LiDAR (Light Detection and Ranging) to irradiate a laser beam and measure the distance to an object, the shape of the object, etc. based on information on the reflected light. The range finding device 50 includes a light emitting unit 501, a light receiving unit 502, a control unit 503, and a connector 504.

[0011] The connector 504 is a mechanism for attaching the distance measuring device 50 to the camera body 2. When the connector 504 is inserted into the accessory shoe 26 of the camera body 2 (described later), the connector 504 is fixed to the accessory shoe 26, and the distance measuring device 50 is attached to the camera body 2. When the distance measuring device 50 is attached to the camera body 2, electrical contacts on the connector 504 come into physical contact with electrical contacts on the accessory shoe 26, and are electrically connected. This enables communication between the distance measuring device 50 (control unit 503) and the camera body 2 (body control unit 21).

[0012] The light-emitting unit 501 is, for example, a vertical-cavity surface-emitting laser (VCSEL), and emits laser light such as near-infrared light toward a target area. Here, the target area is an area that corresponds to the imaging range of the distance measuring device 50 and is an area that corresponds to the angle of view of the distance measuring device 50.

[0013] The light receiving unit 502 detects light from the target area. Specifically, the light receiving unit 502 is an imaging element that detects light emitted from the light emitting unit 501 and reflected by an object (target) within the target area. The light receiving unit 502 includes a light receiving pixel unit 502a and a light receiving pixel control unit 502b. In the following description, light reflected by an object within the target area will be referred to as reflected light.

[0014] The light-receiving pixel unit 502a has a plurality of pixels, each having a photoelectric conversion unit. The plurality of pixels are arranged two-dimensionally (in the row and column directions). The photoelectric conversion unit is configured by a photodiode (PD) or a SPAD (Single Photon Avalanche Diode), which has higher sensitivity than a photodiode. In this embodiment, the description will proceed assuming that the photoelectric conversion unit is a photodiode.

[0015] The photoelectric conversion unit of each pixel of the light-receiving pixel unit 502a receives reflected light emitted by the light-emitting unit 501 and accumulates electric charges corresponding to the amount of reflected light. More specifically, the photoelectric conversion unit of each pixel accumulates electric charges corresponding to the amount of reflected light received within a predetermined exposure time. Then, in accordance with a control signal from the light-receiving pixel control unit 502b, the light-receiving pixel unit 502a outputs a signal corresponding to the electric charges accumulated in the photoelectric conversion unit from each pixel to the control unit 503.

[0016] The light-receiving pixel control unit 502b causes each pixel of the light-receiving pixel unit 502a to accumulate charge based on an instruction signal from the control unit 503, and causes each pixel to output a signal based on the accumulated charge.

[0017] The control unit 503 uses the signals output from each pixel of the light-receiving pixel unit 502a to calculate the time Δt from when the light-emitting unit 501 emits light to when the reflected light of the emitted light is received by the light-receiving unit 502, and calculates the distance to an object within the target area based on the time Δt and the speed of light.

[0018] Specifically, the control unit 503 includes a generation unit 505 that calculates the distance to an object for each pixel of the light-receiving pixel unit 502a and generates an image in which the pixel value is (a value corresponding to) that distance, and an image in which the pixel value is information based on the intensity of reflected light (hereinafter, these will be collectively referred to as a distance image). The control unit 503 outputs the generated distance image to a body control unit 21 of the camera body 2, which will be described later. In this embodiment, the control unit 503 outputs to the body control unit 21, of the generated distance images, a distance image that corresponds to the imaging range of the camera 1. Note that instead of a distance image, the control unit 503 may generate data from which the distance to an object can be calculated (for example, data including the time Δt for each pixel) and output this to the body control unit 21.

[0019] (Interchangeable Lens 3) The interchangeable lens 3 includes a lens-side mount unit 301, a photographing optical system (imaging optical system) 31, a lens control unit 32, and a lens memory 33. The lens-side mount unit 301 includes a lens-side connection unit 302. The lens-side connection unit 302 has multiple terminals, such as a terminal for a clock signal, a terminal for a data signal, and a terminal for power supply. The interchangeable lens 3 is detachably attached to the camera body 2 by the lens-side mount unit 301 and a body-side mount unit 201, which will be described later.

[0020] The photographing optical system 31 includes a plurality of lenses, including a zoom lens (variable magnification lens) 31 a that changes the focal length and a focus lens (focus adjustment lens) 31 b, and an aperture 31 c, and forms a subject image on the imaging surface 22 a of the imaging element 22.

[0021] The lens control unit 32 is composed of a processor such as a CPU, FPGA, or ASIC, and memories such as ROM and RAM, and controls each component of the interchangeable lens 3 based on a control program. The lens control unit 32 controls the position of the zoom lens 31a, the position of the focus lens 31b, and the drive of the aperture 31c based on signals output from the body control unit 21 of the camera body 2. When a signal indicating the direction and amount of movement of the focus lens 31b is input from the body control unit 21, the lens control unit 32 adjusts the focal position of the photographic optical system 31 by moving the focus lens 31b back and forth along the optical axis OA1 based on the signal. The lens control unit 32 also controls the position of the zoom lens 31a and the aperture diameter of the aperture 31c based on signals output from the body control unit 21 of the camera body 2. The lens control unit 32 may also control the position of the zoom lens 31a in response to operation of a zoom ring (not shown) provided on the interchangeable lens 3.

[0022] The lens memory 33 is configured, for example, by a non-volatile storage medium. Information related to the interchangeable lens 3 is stored (recorded) in the lens memory 33 as lens information. The lens information includes data on the optical characteristics (exit pupil distance and F-number) of the photographic optical system 31, data on the shortest shooting distance of the photographic optical system 31, and the like. The lens information differs depending on the type of interchangeable lens 3. The lens information may also be stored in an internal memory of the lens control unit 32. The lens information may also be stored in a body memory 23 provided in the camera body 2, which will be described later. In this case, the body memory 23 stores lens information for multiple interchangeable lenses 3.

[0023] Reading of data from the lens memory 33 is controlled by the lens control unit 32. When the interchangeable lens 3 is attached to the camera body 2, the lens control unit 32 transmits lens information to the body control unit 21 via the terminals of the lens side connection unit 302 and the body side connection unit 202. The lens control unit 32 also transmits to the body control unit 21 position information (focal length information) of the controlled zoom lens 31a, position information of the controlled focus lens 31b, information on the controlled aperture value (F-number) of the photographic optical system 31, and the like.

[0024] The lens control unit 32 communicates by sending and receiving information bidirectionally between the camera body 2 and the interchangeable lens 3 via the terminals of the lens side connection unit 302 and the body side connection unit 202. When the zoom lens 31a moves and the focal length of the photographic optical system 31 changes, the lens control unit 32 may send information about the focal length of the photographic optical system 31 and information about the aperture value of the photographic optical system 31 to the body control unit 21, or may periodically send information about the focal length of the photographic optical system 31 and information about the aperture value of the photographic optical system 31 to the body control unit 21.

[0025] (Camera Body 2) The camera body 2 includes a body-side mount unit 201, an image sensor 22, a body memory 23, a display unit 24, an operation unit 25, an accessory shoe 26, and a body control unit 21.

[0026] The body side mount section 201 includes a body side connection section 202. The body side connection section 202 has a plurality of terminals, such as a terminal for a clock signal, a terminal for a data signal, and a terminal for power supply.

[0027] When the interchangeable lens 3 is attached to the camera body 2, a terminal provided on the body-side connector 202 is electrically connected to a terminal provided on the lens-side connector 302. This enables power to be supplied from the camera body 2 to the interchangeable lens 3 and communication between the camera body 2 and the interchangeable lens 3.

[0028] The image sensor 22 is a CMOS image sensor or a CCD image sensor. The image sensor 22 captures an image of a subject formed by the photographing optical system 31. The image sensor 22 includes a pixel unit 221 in which a plurality of pixels each having a photoelectric conversion unit are arranged two-dimensionally (in the row and column directions), and a control unit 222 that controls the pixel unit 221. The photoelectric conversion unit is composed of a photodiode.

[0029] The pixel section 221 has imaging pixels that photoelectrically convert received light in a photoelectric conversion section and output signals used for image generation, and focus detection pixels that photoelectrically convert received light in a photoelectric conversion section and output signals used for focus detection.

[0030] The control unit 222 causes the focus detection pixels to output signals based on instruction signals from the body control unit 21. The control unit 222 also causes the imaging pixels to output signals based on instruction signals from the body control unit 21.

[0031] The body memory 23 is composed of, for example, a non-volatile storage medium, etc. Image data, control programs, etc. are recorded in the body memory 23. Writing data to the body memory 23 and reading data from the body memory 23 are controlled by the body control unit 21. The display unit 24 displays an image based on the image data, an image showing a focus detection area (AF area) such as an AF frame, information related to shooting such as the shutter speed and F-number, a menu screen, etc.

[0032] The operation unit 25 includes various setting switches such as a release button, a power switch, and switches for switching between various modes, and outputs operation signals corresponding to the respective operations to the body control unit 21 .

[0033] The accessory shoe 26 has electrical contacts that connect with electrical contacts of the connector 504 of the distance measuring device 50. The distance measuring device 50 is detachably attached to the accessory shoe 26.

[0034] The body control unit 21 is configured with a processor such as a CPU, FPGA, or ASIC, and memories such as ROM and RAM, and controls each unit of the camera 1 based on a control program. The body control unit 21 also determines the drive position of the focus lens 31b provided in the interchangeable lens 3 based on signals from the focus detection pixels, and transmits drive instructions for the focus lens 31b and the like to the lens control unit 32. The body control unit 21 also determines the drive position of the focus lens 31b provided in the interchangeable lens 3 based on distance images and the like output from the distance measuring device 50, and transmits drive instructions for the focus lens 31b and the like to the lens control unit 32.

[0035] The body control unit 21 also controls the exposure conditions (for example, exposure time) of the image sensor 22. For example, the body control unit 21 controls the exposure time of the image sensor 22 based on the aperture value of the photographing optical system 31.

[0036] In addition, the body control unit 21 determines the exposure time of the light-receiving pixel unit 502a of the light-receiving unit 502 of the distance measuring device 50 based on information about the photographing optical system 31, and outputs the determined exposure time to the control unit 503 of the distance measuring device 50.

[0037] In this embodiment, for example, when the camera body 2 is powered on and communication with the distance measuring device 50 becomes possible, or when the release button (operation unit 25) is half-pressed, i.e., when an instruction to perform focus detection (hereinafter referred to as an AF instruction) is received, the body control unit 21 determines the exposure time for the initial exposure process of the light receiving pixel unit 502a according to the focal length of the photographing optical system 31. The exposure time for the initial exposure process of the light receiving pixel unit 502a is the exposure time for the first exposure process executed by the light receiving pixel unit 502a after receiving the AF instruction. This process will be described in detail below.

[0038] FIG. 2 is a flowchart showing an example of processing executed by the body control unit 21, and FIG. 3 is a flowchart showing an example of processing executed by the control unit 503 of the distance measuring device 50.

[0039] 2 starts, for example, when the power to the camera body 2 is turned on and it is confirmed that the distance measuring device 50 is attached to the camera body 2. When the processing in Fig. 2 starts, the body control unit 21 waits until it receives an AF command (the release button is half-pressed) (step S11 / NO).

[0040] When the body control unit 21 receives an AF instruction (step S11 / YES), it acquires the current focal length of the photographing optical system 31 from the lens control unit 32 of the interchangeable lens 3 (step S13).

[0041] Here, we will explain why the body control unit 21 acquires the current focal length of the photographic optical system 31. Figures 4A and 4B are diagrams showing the relationship between exposure time and distance measurement results in the distance measurement device 50. Figure 4A is a diagram showing the relationship between exposure time and distance measurement results when an 18% gray chart is placed 2 m from the distance measurement device 50, and Figure 4B is a diagram showing the relationship between exposure time and distance measurement results when an 18% gray chart is placed 5 m from the distance measurement device 50. In Figures 4A and 4B, the horizontal axis represents exposure time, and the vertical axis represents distance measurement results.

[0042] 4A, when an 18% gray chart is placed 2 m from the distance measuring device 50, distance measurement results cannot be obtained (the distance to the 18% gray chart cannot be measured) if the exposure time is 400 μsec or less, but distance measurement results can be obtained if the exposure time is 800 μsec or more. Furthermore, the longer the exposure time, the smaller the variation in distance measurement results and the higher the distance measurement accuracy.

[0043] 4B, when an 18% gray chart is placed 5 m from the distance measuring device 50, distance measurement results cannot be obtained (the distance to the 18% gray chart cannot be measured) if the exposure time is 1600 μsec or less, but distance measurement results can be obtained if the exposure time is 3200 μsec or more. Furthermore, the longer the exposure time, the smaller the variation in distance measurement results and the higher the distance measurement accuracy.

[0044] 4C, the distance that can be measured by the distance measuring device 50 is proportional to the exposure time of the distance measuring device 50. In other words, if the distance to the subject increases, the exposure time must be increased in order to measure the distance to the subject.

[0045] When distance images generated by the distance measuring device 50 are used in the camera 1, it is preferable that the distance images be sent to the camera 1 frequently. In other words, it is preferable that the distance measuring device 50 has a short generation cycle for distance images. The generation cycle for distance images can be shortened by shortening the exposure time of the light receiving pixel unit 502a. On the other hand, if the distance to an object in the target area is long, the exposure time must be lengthened to obtain an accurate distance to the object. Therefore, in this embodiment, the body control unit 21 determines the exposure time for the first exposure process of the distance measuring device 50 based on the focal length of the photographing optical system 31, thereby ensuring distance measurement accuracy and shortening the generation cycle for distance images.

[0046] 2 , when the body control unit 21 acquires the focal length of the photographing optical system 31 (step S13), it determines whether the focal length is equal to or less than a first threshold value (step S15). The first threshold value is a focal length corresponding to a distance that the distance measuring device 50 cannot measure no matter how long the exposure time of the light receiving pixel unit 502a is extended. In other words, if the focal length is equal to or greater than the first threshold value, the shooting distance estimated from the focal length is a distance that the distance measuring device 50 cannot measure. That is, in step S15, it is determined whether the distance from the distance measuring device 50 to the subject is equal to or less than a distance that the distance measuring device 50 can measure.

[0047] If the focal length is greater than the first threshold value (step S15 / NO), the distance measuring device 50 cannot measure the distance no matter how long the exposure time of the light receiving pixel unit 502a is extended, and therefore the process proceeds to step S25.

[0048] On the other hand, if the focal length is equal to or less than the first threshold (step S15 / YES), the body control unit 21 determines the exposure time of the light-receiving pixel unit 502a of the distance measuring device 50 based on the focal length of the photographic optical system 31 (step S17). For example, the body control unit 21 estimates the distance to the subject based on the focal length of the photographic optical system 31 and the size of the subject detection frame corresponding to the shooting mode set in the camera body 2. The body control unit 21 determines the exposure time based on, for example, the estimated distance to the subject and the graph of FIG. 4C. For example, if the estimated distance to the subject is D1, the body control unit 21 determines the exposure time to be the exposure time T1 corresponding to the measurable distance D1 in FIG. 4C. Note that the body control unit 21 may determine the exposure time based on, for example, a graph or a formula that defines the relationship between the focal length of the photographic optical system 31 and the exposure time. Note that if the camera body 2 is not set to detect a subject, the body control unit 21 may select the distance to the subject with the highest probability based on an analysis of past shooting data, or may determine the distance to the subject by multiplying the focal length by a predetermined factor.

[0049] Next, the body control unit 21 outputs a distance measurement process start instruction and the exposure time determined in step S17 to the control unit 503 of the distance measurement device 50 (step S19).

[0050] Meanwhile, the control unit 503 of the distance measuring device 50 waits until it receives a distance measurement process start instruction and an exposure time from the body control unit 21 (FIG. 3: step S101 / NO). When the control unit 503 receives the distance measurement process start instruction and the exposure time (step S101 / YES), it executes a first exposure process (step S103). The first exposure process is an exposure process in which the exposure time of the light receiving pixel unit 502a is the exposure time received from the body control unit 21.

[0051] Next, when the first exposure process is completed, the control unit 503 generates a distance image based on information corresponding to the intensity of the reflected light (step S105) and transfers the generated distance image to the body control unit 21 (step S107). At this time, the control unit 503 transfers to the body control unit 21 a portion of the generated distance image that corresponds to the imaging range of the camera 1. Note that the control unit 503 may transfer the entire generated distance image to the body control unit 21.

[0052] Figure 5(A) is a diagram showing an example of the imaging range of camera 1 at a certain point in time, and Figure 5(B) is a diagram showing an example of a distance image generated based on a signal output from the light receiving unit 502 of the distance measuring device 50 at a certain point in time.

[0053] As shown in FIG. 5B, the imaging range of the distance measuring device 50 at a given time is larger than the imaging range of the camera 1 at a given time shown in FIG. 5A. In this embodiment, the body control unit 21 controls the camera body 2 and the interchangeable lens 3, for example, using information about the distance to the subject. Therefore, it is sufficient for the body control unit 21 to acquire a distance image of a portion corresponding to the imaging range of the camera 1, rather than a distance image corresponding to the entire surface of the light receiving pixel unit 502a. Furthermore, transmitting a distance image corresponding to the entire surface of the light receiving pixel unit 502a as is would increase the data volume and lengthen communication time. Therefore, in this embodiment, the control unit 503 acquires information about the imaging range of the camera 1 and transfers to the body control unit 21 a distance image of a portion of the generated distance image that corresponds to the imaging range of the camera 1. That is, in the example of FIG. 5B, the control unit 503 transfers to the body control unit 21 a distance image of the portion indicated by the dotted line, which corresponds to the imaging range of the camera 1 shown in FIG. 5A.

[0054] For example, the control unit 503 obtains the current focal length of the photographing optical system 31 from the body control unit 21 and calculates the angle of view of the camera 1. Then, the control unit 503 determines the portion of the generated distance image that corresponds to the imaging range of the camera 1 based on the pre-registered relationship between the angle of view of the distance measuring device 50 and the angle of view of the camera 1. The control unit 503 then extracts the distance image of the portion that corresponds to the imaging range of the camera 1 and transfers it to the body control unit 21.

[0055] Alternatively, the control unit 503 may determine the portion of the distance image that corresponds to the imaging range of the camera 1 based on a defocus amount calculated based on signals output from focus detection pixels of the image sensor 22 included in the camera body 2. Specifically, the body control unit 21 calculates the defocus amount based on signals output from the focus detection pixels of the image sensor 22, and generates an image (hereinafter referred to as a reference image) whose pixel values ​​are the defocus amount (or a value corresponding to that defocus amount). The body control unit 21 transmits the generated reference image to the control unit 503. Meanwhile, the control unit 503 performs pattern matching between the received reference image and the generated distance image, and extracts a distance image of the portion of the distance image that corresponds to the reference image from the result. The control unit 503 then transfers the extracted distance image to the body control unit 21.

[0056] In this way, by transferring the distance image of the portion corresponding to the imaging range of the camera 1, the transmission time of the distance image can be shortened.

[0057] Returning to FIG. 3, when the process of step S107 is completed, the control unit 503 determines the exposure time of the light-receiving pixel unit 502a based on the signal output from the light-receiving pixel unit 502a in step S105 (step S109).

[0058] Next, the control unit 503 executes a second exposure process (step S111). The second exposure process is an exposure process in which the exposure time of the light-receiving pixel unit 502a is determined based on the signal output from the light-receiving pixel unit 502a. That is, after the first exposure process is completed, the distance measuring device 50 executes an automatic exposure process.

[0059] When the second exposure process is completed, the control unit 503 generates a distance image based on the intensity of the reflected light (step S113) and transfers the distance image of the portion corresponding to the imaging range of the camera 1 to the body control unit 21 (step S115).

[0060] 2 , the body control unit 21 of the camera body 2 outputs a distance measurement process start command and an exposure time (step S19), and then determines whether the focal length of the photographic optical system 31 has been changed (step S21). The focal length of the photographic optical system 31 is changed, for example, by the user rotating a zoom ring provided on the interchangeable lens 3 or by operating the operation unit 25 of the camera body 2. Note that the focal length of the photographic optical system 31 may be periodically transmitted from the lens control unit 32 to the body control unit 21, or may be transmitted from the lens control unit 32 to the body control unit 21 when the focal length of the photographic optical system 31 is changed.

[0061] If the focal length of the photographing optical system 31 has not changed (step S21 / NO), the process proceeds to step S25. On the other hand, if the focal length has been changed (step S21 / YES), it is determined whether the amount of change in the focal length of the photographing optical system 31 is equal to or greater than a second threshold (step S23). Generally, when the distance between the object and the distance measuring device 50 changes, the focal length of the photographing optical system 31 is changed. If the amount of change in the distance between the object and the distance measuring device 50 is large, the current exposure time may be insufficient, resulting in a decrease in distance measurement accuracy, or conversely, the exposure time may be too long, resulting in a long cycle of acquiring distance images. Therefore, the amount of change in the focal length of the photographing optical system 31 corresponding to the amount of change in the distance between the object and the distance measuring device 50, which is thought to affect the exposure time, is set as the second threshold.

[0062] If the change in the focal length of the photographic optical system 31 is equal to or greater than the second threshold value (step S23 / YES), the body control unit 21 determines the exposure time (step S33) in the same manner as in step S17, based on the current focal length of the photographic optical system 31. Thereafter, the body control unit 21 outputs the determined exposure time to the control unit 503 of the distance measuring device 50 (step S35).

[0063] If the focal length is greater than the first threshold value (step S15 / NO), if the focal length has not been changed (step S21 / NO), if the amount of change in focal length is less than the second threshold value (step S23 / NO), or after outputting the exposure time (step S35), the body control unit 21 determines whether or not a shooting instruction has been received (step S25). For example, the body control unit 21 determines that a shooting instruction has been received when the release button has been fully pressed.

[0064] If a shooting instruction has been received (step S25 / YES), the body control unit 21 executes shooting processing (step S31).

[0065] After the photographing process (step S31) is completed, or if a photographing instruction has not been received (step S25 / NO), the body control unit 21 determines whether the AF instruction has been released (step S27). For example, the body control unit 21 determines that the AF instruction has been released when the half-press of the release button has been released.

[0066] If the AF instruction has been cancelled (step S27 / YES), the body control unit 21 outputs a distance measurement processing end instruction to the control unit 503 (step S29), and the process returns to step S11. On the other hand, if the AF instruction has not been cancelled (step S27 / NO), the process returns to step S21.

[0067] 3, after transferring the distance image obtained by the second exposure process to the body control unit 21 (step S115), the control unit 503 determines whether a new exposure time has been received from the body control unit 21 (step S117). The exposure time received in step S117 is the exposure time that is determined when the focal length of the photographic optical system 31 has changed by more than the second threshold value.

[0068] If a new exposure time has been received from the body control unit 21 (YES in step S117), the process returns to step S103. That is, if a new exposure time has been received from the body control unit 21, the control unit 503 executes a first exposure process in which the exposure time received from the body control unit 21 is set as the exposure time of the light receiving pixel unit 502a (step S103).

[0069] On the other hand, if a new exposure time has not been received from the body control unit 21 (step S117 / NO), it is determined whether or not an instruction to end the ranging process has been received (step S119). If an instruction to end the ranging process has not been received (step S119 / NO), the process returns to step S109. In other words, if a new exposure time has not been received from the body control unit 21 and an instruction to end the ranging process has not been received, the second exposure process is executed again using the exposure time determined based on the signal output from the light receiving pixel unit 502a.

[0070] On the other hand, if the distance measurement process end instruction is received (step S119 / YES), the control unit 503 ends the process of FIG.

[0071] The processing of FIGS. 2 and 3 will be described with reference to the sequence diagram of FIG.

[0072] 6 , assume that the body control unit 21 receives an AF command at time t1. In this case, the body control unit 21 acquires the focal length of the photographic optical system 31 at time t1 from the lens control unit 32 of the interchangeable lens 3 (ST1). Assume that the acquired focal length is equal to or less than a first threshold value. In this case, the body control unit 21 determines the exposure time of the light-receiving pixel unit 502a of the rangefinder device 50 based on the acquired focal length of the photographic optical system 31, and outputs a distance measurement process start command and the determined exposure time to the control unit 503 of the rangefinder device 50 (ST2). Alternatively, the body control unit 21 may periodically acquire the focal length of the photographic optical system 31 and determine the exposure time of the light-receiving pixel unit 502a of the rangefinder device 50 based on the most recent focal length among the acquired focal lengths.

[0073] The control unit 503 of the distance measuring device 50 starts distance measurement processing when it receives a distance measurement processing start instruction at time t3, for example. At this time, in the exposure processing for the first distance measurement processing (distance measurement 1), the light receiving pixel unit 502a is exposed for an exposure time determined by the body control unit 21. In Figure 6, the exposure processing in which the light receiving pixel unit 502a is exposed for an exposure time determined by the body control unit 21 is shown as "Exposure A."

[0074] In distance measurement 1, when the exposure process (exposure A) is completed, a signal is output from the light receiving pixel unit 502a under the control of the control unit 503, and the control unit 503 transfers a distance image, etc. created based on the signal to the body control unit 21.

[0075] When the signal output from the light-receiving pixel unit 502a is completed, the next distance measurement process (distance measurement 2) is started in the distance measuring device 50. At this time, in distance measurement 2, an exposure process is executed to expose the light-receiving pixel unit 502a for an exposure time determined based on the signal output from the light-receiving pixel unit 502a. In Fig. 6, the exposure process to expose the light-receiving pixel unit 502a for an exposure time determined based on the signal output from the light-receiving pixel unit 502a is indicated as "exposure B."

[0076] In distance measurement 2, when exposure B is completed, a signal is output from the light receiving pixel unit 502a under the control of the control unit 503, and the control unit 503 transfers a distance image and the like created based on the signal to the body control unit 21. When signal output from the light receiving pixel unit 502a is completed, distance measurement 3 is started.

[0077] For example, suppose that the focal length is changed by more than the second threshold at time t4. In this case, the body control unit 21 determines the exposure time based on the focal length of the photographic optical system 31 at time t4 and outputs the determined exposure time to the control unit 503 of the distance measuring device 50 (ST3). Having received the exposure time from the body control unit 21, the control unit 503 exposes the light-receiving pixel unit 502a for the exposure time determined by the body control unit 21 in the exposure process of the distance measurement process (distance measurement 5 in FIG. 6 ), which is the first process performed after receiving the exposure time. Therefore, in FIG. 6 , the exposure process of distance measurement 5 is exposure A. Then, in distance measurement 6, which is performed after distance measurement 5, exposure B is performed, which exposes the light-receiving pixel unit 502a for the exposure time determined based on the signal output from the light-receiving pixel unit 502a.

[0078] Thereafter, for example, when the body control unit 21 outputs a distance measurement process end instruction at time t5 (ST4), the control unit 503 of the distance measuring device 50 ends the distance measurement process and does not perform new distance measurement process after time t5.

[0079] The distance image transferred from the distance measuring device 50 is used, for example, to calculate the in-focus position of the focus lens 31b. FIG.

[0080] 7 starts, for example, when the power is turned on to the camera body 2. The body control unit 21 determines whether or not a signal (focus detection signal) has been acquired (received) from a focus detection pixel of the image sensor 22 (step S201).

[0081] If a focus detection signal is acquired (step S201 / YES), the body control unit 21 executes focus adjustment processing to focus the subject image on the imaging surface 22a of the image sensor 22 based on the focus detection signal (step S205). Specifically, the body control unit 21 calculates the amount of deviation between the image plane of the image captured by the photographing optical system 31 and the imaging surface 22a of the image sensor 22 based on the focus detection signal. The body control unit 21 converts this deviation into a defocus amount using a predetermined conversion formula. Based on the calculated defocus amount, the body control unit 21 calculates the focus position of the focus lens 31b (the amount of movement of the focus lens 31b to the in-focus position) for the image captured by the photographing optical system 31 to be focused (formed) on the imaging surface 22a of the image sensor 22. Specifically, the body control unit 21 determines whether the defocus amount is within a permissible value. If the defocus amount is within the permissible value, the body control unit 21 determines that the subject image is in focus. On the other hand, if the defocus amount exceeds the allowable value, the body control unit 21 determines that the image is not in focus, and sends a signal to the lens control unit 32 of the interchangeable lens 3 indicating the amount of movement of the focus lens 31b and an instruction to move the lens. The lens control unit 32 moves the focus lens 31b according to the amount of movement, thereby automatically performing focus adjustment. After the processing of step S205 is completed, the process returns to step S201.

[0082] If a focus detection signal has not been acquired (step S201 / NO), the body control unit 21 determines whether a distance image has been acquired (received) from the distance measuring device 50 (step S203).

[0083] If a distance image is acquired from the distance measuring device 50 (step S203 / YES), focus adjustment processing is performed to focus the subject image on the imaging surface 22a of the image sensor 22 based on the distance image (step S207). Specifically, the body control unit 21 acquires the distance to the subject from the distance image. Based on the acquired distance to the subject and the current focal length of the imaging optical system 31, the body control unit 21 calculates the focus position of the focus lens 31b (the amount of movement of the focus lens 31b to the focus position) for the image captured by the imaging optical system 31 to be focused (formed) on the imaging surface 22a of the image sensor 22. The body control unit 21 transmits the amount of movement of the focus lens 31b and a signal instructing lens movement to the lens control unit 32 of the interchangeable lens 3. The lens control unit 32 moves the focus lens 31b according to the amount of movement, thereby automatically performing focus adjustment.

[0084] If a distance image has not been acquired from the distance measuring device 50 (step S203 / NO), or when the processing of step S207 is completed, the process returns to step S201. In this way, the body control unit 21 performs focus adjustment processing based on signals from the focus detection pixels and the distance image, thereby shortening the execution cycle of the focus adjustment processing and improving focusing accuracy.

[0085] As described above in detail, according to the first embodiment, the camera 1 includes an image sensor 22 that captures an image through the photographic optical system 31, a light-emitting unit 501 that emits light, a light-receiving unit 502 that receives light that is emitted by the light-emitting unit 501 and reflected by an object, and a control unit 503 that generates information for calculating the distance to the object based on the light-receiving result of the light-receiving unit 502, and a body control unit 21 that controls the exposure time of the light-receiving unit 502 based on information related to the focal length of the photographic optical system 31. By determining the exposure time in accordance with the focal length of the photographic optical system 31, it is possible to ensure distance measurement accuracy and, in some cases, to set an exposure time that is shorter than a fixed exposure time, thereby shortening the cycle of acquiring distance images.

[0086] Furthermore, in the first embodiment, the distance measuring device 50 is detachable from the camera 1, and the body control unit 21 of the camera 1 outputs the exposure time of the light receiving unit 502 to the distance measuring device 50. This allows the control unit 503 of the distance measuring device 50 to control the exposure time of the light receiving unit 502 based on the exposure time received from the body control unit 21.

[0087] Furthermore, in the first embodiment, when the focal length of the photographic optical system 31 is changed by a value equal to or greater than the second threshold, the body control unit 21 controls the exposure time of the light receiving unit 502 in the first exposure process (for example, distance measurement 5 in FIG. 6 ) after the focal length of the photographic optical system 31 is changed by a value equal to or greater than the second threshold, based on the focal length of the photographic optical system 31. This makes it possible to prevent, for example, an insufficient exposure time from reducing distance measurement accuracy, or, conversely, an excessively long exposure time from lengthening the cycle for acquiring distance images.

[0088] Furthermore, according to the first embodiment, the distance measuring device 50 includes a light emitting unit 501 that emits light, a light receiving unit 502 that receives light that is reflected by an object and that is emitted by the light emitting unit 501, and a control unit 503 that generates a distance image based on the light reception result of the light receiving unit 502 and transmits to the camera 1 a distance image of a portion of the generated distance image that corresponds to the imaging range of the camera 1. This makes it possible to reduce the time required to transmit the distance image compared to transmitting a distance image that corresponds to the entire surface of the light receiving unit 502.

[0089] In the first embodiment, the body control unit 21 determines the exposure time of the light receiving pixel unit 502a based on the focal length, but for example, the body control unit 21 may determine the exposure time based on the shortest shooting distance of the photographic optical system 31. In this case, the body control unit 21 may determine the exposure time based on the shortest shooting distance of the photographic optical system 31 acquired through communication with the interchangeable lens 3 when the camera body 2 is powered on.

[0090] Second Embodiment In the first embodiment, the body control unit 21 determines the exposure time of the light receiving pixel unit 502 a based on the focal length of the photographic optical system 31. However, this is not limited to this. In the second embodiment, the body control unit 21 determines the exposure time of the light receiving pixel unit 502 a based on the aperture value of the photographic optical system 31.

[0091] Here, a method for determining the exposure time of the light-receiving pixel unit 502a based on the aperture value of the photographing optical system 31 will be described.

[0092] FIG. 8 shows the relationship between the exposure time and the distance measurement result when an 18% gray chart is placed at a position 2 m from the distance measuring device 50.

[0093] As explained in FIG. 4A, the longer the exposure time, the smaller the variation in the distance measurement results and the more accurate the distance measurement.

[0094] 8 shows a range RNG1 in which the image appears to be in focus when the aperture value is V1, and a range RNG2 in which the image appears to be in focus when the aperture value is V2, which is greater than V1. The smaller the aperture value of the photographing optical system 31, the shallower the depth of field, and the larger the aperture value, the deeper the depth of field. The deeper the depth of field, the wider the range in which the image appears to be in focus, so range RNG2 is wider than range RNG1.

[0095] When the aperture value is V1, if the distance between the object and the distance measuring device 50 is within range RNG1, the object appears to be in focus, and when the aperture value is V2 (>V1), which is larger than V1, if the distance between the object and the distance measuring device 50 is within range RNG2, the object appears to be in focus. Therefore, for example, when the aperture value is V2, even if the distance measurement results vary, as long as the distance measurement results are within range RNG2, it is thought that the object (subject) will be in focus even if the focus lens 31b of the photographing optical system 31 is driven based on the distance measurement results of the distance measuring device 50.

[0096] Therefore, in the second embodiment, when the aperture value is V2, for example, the body control unit 21 determines the shortest exposure time among the exposure times whose ranging results fall within range RNG2 as the exposure time for the light receiving pixel unit 502a. In the example of Fig. 8, when the exposure time is 600 [μsec], there is a large variation in the ranging results, but because the ranging results fall within range RNG2, 600 [μsec] is determined as the exposure time for the light receiving pixel unit 502a.

[0097] On the other hand, when the aperture value is V1, the body control unit 21 determines the shortest exposure time among the exposure times for which the distance measurement results fall within range RNG1 as the exposure time for the light-receiving pixel unit 502a. In the case of FIG. 8, even if the exposure time is 3200 [μsec], there are distance measurement results that fall outside range RNG1. When the exposure time becomes 4800 [μsec], the distance measurement results fall within range RNG1. Therefore, when the aperture value is V1, the body control unit 21 determines 4800 [μsec] as the exposure time for the light-receiving pixel unit 502a.

[0098] Fig. 9 is a flowchart showing an example of processing executed by the body control unit 21 according to the second embodiment. In Fig. 9, processing that is the same as the processing in Fig. 2 is given the same reference numerals, and detailed description thereof will be omitted. Note that processing executed by the control unit 503 of the distance measuring device 50 is the same as in Fig. 3, and detailed description thereof will be omitted.

[0099] 9 starts, for example, when the power is turned on to the camera body 2. When the body control unit 21 receives an AF instruction (step S11 / YES), it acquires the current aperture value of the photographic optical system 31 from the lens control unit 32 of the interchangeable lens 3 (step S41).

[0100] Next, the body control unit 21 determines the exposure time of the light receiving pixel unit 502a based on the aperture value of the photographic optical system 31 (step S43). The body control unit 21 determines the exposure time using, for example, a table in which the exposure time of the light receiving pixel unit 502a is set for each aperture value of the photographic optical system 31. This table is created, for example, based on the relationship between the distance measurement results and the depth of field shown in FIG. 8. The body control unit 21 may determine the exposure time based, for example, on a predetermined calculation formula.

[0101] Next, the body control unit 21 outputs a distance measurement process start instruction and the determined exposure time to the control unit 503 of the distance measuring device 50 (step S19). After outputting the distance measurement process start instruction and the exposure time, the body control unit 21 determines whether the aperture value of the photographic optical system 31 has been changed (step S45).

[0102] If the aperture value of the photographic optical system 31 has been changed (step S45 / YES), the body control unit 21 determines the exposure time (step S47) in the same manner as in step S43, based on the current aperture value of the photographic optical system 31. Thereafter, the body control unit 21 outputs the determined exposure time to the control unit 503 of the distance measuring device 50 (step S35).

[0103] On the other hand, if the aperture value of the photographing optical system 31 has not been changed (step S45 / NO), the body control unit 21 determines whether or not a photographing instruction has been received (step S25). The subsequent processing is the same as in FIG. 2, and therefore a detailed description thereof will be omitted.

[0104] The processing of FIGS. 9 and 3 will be described with reference to the sequence diagram of FIG.

[0105] 10, it is assumed that the body control unit 21 receives an AF command at time t11. In this case, the body control unit 21 acquires the aperture value of the photographic optical system 31 at time t11 from the lens control unit 32 of the interchangeable lens 3 (ST11).

[0106] The body control unit 21 determines the exposure time of the light receiving pixel unit 502a of the distance measuring device 50 based on the acquired aperture value, and outputs a distance measurement process start instruction and the determined exposure time to the control unit 503 of the distance measuring device 50 (ST12). Note that the body control unit 21 may periodically acquire the aperture value of the photographing optical system 31, and use the most recent aperture value from the acquired aperture values ​​to determine the exposure time of the light receiving pixel unit 502a.

[0107] The control unit 503 of the distance measuring device 50 starts distance measurement processing when it receives a distance measurement processing start instruction and an exposure time at time t13, for example. At this time, in the exposure processing for the first distance measurement processing (distance measurement 1), the light receiving pixel unit 502a is exposed for the exposure time determined by the body control unit 21.

[0108] In distance measurement 1, when the exposure process (exposure A) is completed, a signal is output from the light receiving pixel unit 502a under the control of the control unit 503, and the control unit 503 transfers a distance image, etc. created based on the signal to the body control unit 21.

[0109] When the signal output from the light-receiving pixel unit 502a is completed, the next distance measurement process (distance measurement 2) is started in the distance measuring device 50. At this time, in distance measurement 2, an exposure process is executed to expose the light-receiving pixel unit 502a for an exposure time determined based on the signal output from the light-receiving pixel unit 502a.

[0110] In distance measurement 2, when exposure B is completed, a signal is output from the light-receiving pixel unit 502a under the control of the control unit 503, and the control unit 503 transfers a distance image created based on the signal to the body control unit 21. When the signal output from the light-receiving pixel unit 502a is completed, distance measurement 3 is started.

[0111] For example, suppose the aperture value is changed at time t14. In this case, the body control unit 21 determines the exposure time based on the aperture value of the photographing optical system 31 at time t14 and outputs the determined exposure time to the control unit 503 of the distance measuring device 50 (ST13). For example, if the aperture value changed at time t14 is larger than the aperture value acquired at time t11, the exposure time for distance measuring 5 will be shorter than the exposure time for distance measuring 1. On the other hand, if the aperture value changed at time t14 is smaller than the aperture value acquired at time t11, the exposure time for distance measuring 5 will be longer than the exposure time for distance measuring 1. In this way, by determining the exposure time based on the aperture value, it may be possible to set an exposure time shorter than the exposure time determined based on the output from the light receiving pixel unit 502a or a fixed exposure time, thereby shortening the cycle for acquiring distance images.

[0112] Thereafter, for example, when the body control unit 21 outputs an instruction to end the distance measurement process at time t15 (ST14), the control unit 503 of the distance measuring device 50 ends the distance measurement process and does not perform new distance measurement process after time t15.

[0113] As in the second embodiment, the body control unit 21 may determine the exposure time of the light receiving unit 502 of the distance measuring device 50 based on the aperture value of the photographing optical system 31 .

[0114] In the first and second embodiments, the distance measuring device 50 is detachable from the camera 1, but the camera 1 may be provided with the distance measuring device 50. In this case, when the power of the camera body 2 is turned on, the process of Fig. 2, for example, is started.

[0115] In the first and second embodiments, the body control unit 21 of the camera body 2 determines the exposure time of the light receiving pixel unit 502a based on the focal length or aperture value of the photographing optical system 31. However, this is not limiting. For example, the control unit 503 of the distance measuring device 50 may determine the exposure time of the light receiving pixel unit 502a based on the focal length or aperture value of the photographing optical system 31.

[0116] Furthermore, in the first and second embodiments described above, the exposure time of the light receiving pixel unit 502a was determined based on the focal length or aperture value of the photographic optical system 31, but the sensitivity of the light receiving pixel unit 502a may also be determined based on the focal length or aperture value of the photographic optical system 31. In other words, the body control unit 21 may determine, based on the focal length or aperture value of the photographic optical system 31, exposure conditions for the light receiving pixel unit 502a that can shorten the cycle of acquiring distance images while ensuring distance measurement accuracy.

[0117] Furthermore, in the first and second embodiments, the interchangeable lens 3 was a zoom lens with a variable focal length, but the interchangeable lens 3 may be a fixed focal length lens. Furthermore, in the first and second embodiments, the focal length was changed by changing the position of the zoom lens 31 a by rotating a zoom ring provided on the interchangeable lens 3, but the position of the zoom lens 31 a may be changed mechanically (for example, via a cam barrel, etc.) in response to the rotation of the zoom ring, or may be electrically driven and controlled by the lens control unit 32. Furthermore, in the first and second embodiments, the interchangeable lens 3 was detachable from the camera body 2, but this is not limited thereto, and the interchangeable lens 3 and the camera body 2 may be integrated.

[0118] Furthermore, by combining the first and second embodiments described above, the body control unit 21 of the camera body 2 may determine the exposure time of the light receiving pixel unit 502a based on both the focal length of the photographing optical system 31 and the aperture value of the photographing optical system 31.

[0119] Furthermore, in the first and second embodiments, the body control unit 21 determines whether an AF instruction has been received (FIGS. 2 and 9), but it may also determine whether a video shooting instruction has been received in addition to whether an AF instruction has been received. In other words, the first and second embodiments can also be applied to video shooting.

[0120] The above-described embodiment is not limited to this, and various modifications can be made without departing from the spirit and scope of the invention.

[0121] REFERENCE SIGNS LIST 1 camera 2 camera body 3 interchangeable lens 21 body control unit 22 imaging element 31 photographing optical system 50 distance measuring device 501 light emitting unit 502 light receiving unit 503 control unit

Claims

1. An imaging device including an imaging element that images an image by an optical system, a light emitting unit that emits light, a light receiving unit that receives light reflected by an object from the light emitted by the light emitting unit, and a generation unit that generates information for calculating the distance to the object based on the light receiving result of the light receiving unit, and a control unit that controls the exposure condition of the light receiving unit of the distance measuring device based on information regarding the optical system.

2. The distance measuring device is detachable from the imaging device, and the control unit outputs the exposure condition of the light receiving unit to the distance measuring device when the distance measuring device is attached to the imaging device. The imaging device according to claim 1.

3. The information regarding the optical system includes at least one of information on the shortest shooting distance of the optical system, information on the focal length of the optical system, and information on the aperture value of the optical system. The imaging device according to claim 1 or claim 2.

4. The control unit shortens the exposure time of the light receiving unit as the aperture value of the optical system increases. The imaging device according to any one of claims 1 to 3.

5. When the control unit receives an instruction to focus an image of a subject on the imaging element, the control unit controls the exposure condition of the light receiving unit for the first time after receiving the instruction based on the information regarding the optical system. The imaging device according to any one of claims 1 to 4.

6. When the focal length of the optical system is changed by a predetermined value or more, the control unit controls the exposure condition of the light receiving unit for the first time after the focal length of the optical system is changed by the predetermined value or more based on the focal length of the optical system. The imaging device according to claim 5.

7. When the aperture value of the optical system is changed, the control unit controls the exposure time of the light receiving unit for the first time after the aperture value of the optical system is changed based on the aperture value of the optical system. The imaging device according to claim 5 or claim 6.

8. The optical system is included in an interchangeable lens attached to the imaging device. The imaging device according to any one of claims 1 to 7.

9. The control unit controls the exposure condition of the imaging element. The imaging device according to any one of claims 1 to 8.

10. A distance measuring device comprising: a light emitting unit that emits light; a light receiving unit that receives light reflected by an object from the light emitted by the light emitting unit; a generating unit that generates information for calculating the distance to the object based on the light receiving result of the light receiving unit; and a transmitting unit that transmits information on a portion corresponding to the imaging range of the imaging device among the information generated by the generating unit to the imaging device.

11. The distance measuring device according to claim 10, wherein the imaging range of the imaging device is determined based on information on the focal length of an optical system detachable from the imaging device.

12. The imaging device includes an imaging element that images an image formed by an optical system, and the imaging range of the imaging device is determined based on information on the focal length of the optical system based on a signal output from the imaging element. The distance measuring device according to claim 10.

13. The distance measuring device according to claim 11 or claim 12, further comprising a control unit that controls the exposure condition of the light receiving unit based on information on the optical system.

14. The information on the optical system includes at least one of information on the shortest shooting distance of the optical system, information on the focal length of the optical system, and information on the aperture value of the optical system. The distance measuring device according to claim 13.

15. The distance measuring device according to claim 14, wherein the control unit shortens the exposure time of the light receiving unit as the aperture value of the optical system increases.

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