JP5927957B2 - Image generation apparatus and exposure start timing adjustment method - Google Patents

Description

  The present invention relates to an image generation apparatus and an exposure start timing adjustment method.

  Conventionally, it is known that the amount of movement per unit time of a curtain by a mechanical shutter is not constant in photographing using the mechanical shutter. For this reason, the exposure time can be adjusted by adjusting the travel characteristics of the front curtain by the electronic shutter to change in accordance with the travel characteristics of the rear curtain by the mechanical shutter in the photographing device that forms the front curtain by the electronic shutter and the rear curtain by the mechanical shutter. Various technologies have been developed to equalize the temperature. For example, in Patent Document 1, in order to prevent the exposure amount at each position of the light receiving sensor from becoming non-uniform due to a change in the exit pupil distance or the like of the lens, the exit pupil distance of the lens from the lens unit is changed. There is disclosed a technique for acquiring lens information including and adjusting an exposure start timing by an electronic shutter based on the lens information.

JP 2008-294753 A

  In the prior art, it is difficult to appropriately adjust the exposure start timing by the electronic shutter according to various conditions. For example, in the technique of Patent Document 1, since the exposure start timing by the electronic shutter is adjusted based on the lens information, the lens information cannot be acquired (for example, another company's lens is used via a conversion lens). It is difficult to appropriately adjust the exposure start timing by the electronic shutter in the state). The present invention has been made in view of the above problems, and an object of the present invention is to provide a technique capable of making the exposure amount at each position of the light receiving sensor uniform under various conditions.

  The image generating apparatus according to the present invention can end the exposure by starting the exposure by resetting the light receiving sensor at a predetermined exposure start timing and then blocking the received light by the shutter. Then, image data corresponding to the amount of light received by the light receiving sensor between the start and end of exposure is generated. In this configuration, the image generation unit generates a plurality of image data indicating that the shutter blocks light at different positions based on the amount of light received by some of the plurality of light receiving elements on the light receiving sensor. The exposure start timing is determined based on the plurality of image data.

  That is, in the image generating apparatus according to the present invention, the shutter is actually operated, and shooting is performed at different timings in the process of blocking the light so that the shutter blocks the light at different positions. A plurality of image data shown are generated, and an exposure start timing is determined based on the plurality of image data. For this reason, it is possible to adjust the exposure start timing in accordance with the actually measured shutter operation, and the exposure amount for each position of the light receiving sensor can be made uniform accurately.

  Furthermore, in the image generating apparatus according to the present invention, the exposure start timing is determined by a part of the plurality of light receiving elements existing on the light receiving sensor (for example, the plurality of light receiving elements having different positions in the moving direction of the shutter). A plurality of image data is generated. That is, the light shielding by the shutter is generally performed in about several milliseconds (for example, 3 to 4 milliseconds), and the running characteristics of the shutter are measured by generating a plurality of image data indicating the shutter light shielding process in a short period. Therefore, as the period required for acquiring each of the plurality of image data is shorter, a larger number of image data can be generated in a few shutter driving processes.

  Therefore, the exposure start timing is adjusted based on image data generated using a part of the light receiving element included in the light receiving sensor. According to this configuration, it is possible to generate image data for adjusting the exposure start timing at a high speed, and it is possible to easily capture a process in which a shutter operating at a high speed blocks light. For example, it is possible to easily acquire a plurality of image data by performing a plurality of shootings while the operation from the start of the light shielding by the shutter to the completion of the light shielding is performed once.

  Here, the light receiving sensor may be any sensor that receives light and outputs the amount of received light. For example, the light receiving element can be configured by a sensor in which light receiving elements that output information according to the amount of received light are two-dimensionally arranged. The shutter only needs to be able to mechanically switch between a state where the light traveling toward the light receiving sensor is blocked and a state where the light is not blocked. For example, a curtain provided on the subject side of the light receiving sensor moves and the shutter moves from the subject. It is composed of a mechanical shutter that blocks the light.

  The exposure start control unit only needs to start exposure by resetting the light receiving sensor. In order to adjust the running characteristics of the front curtain by controlling the exposure start timing, it is necessary to realize an operation (a rolling shutter in the case of a CMOS sensor) that starts exposure for each line in the light receiving element of the light receiving sensor. However, when taking an image for adjusting the exposure start timing, it is preferable to perform an operation of simultaneously starting exposure in a plurality of light receiving elements.

  The image generation unit only needs to be able to generate image data according to the amount of light received by the light receiving sensor during the exposure period. That is, it is only necessary that the image data can be generated according to the amount of light received by the light receiving sensor during the period from the start of exposure by the exposure start control unit to the end of exposure by the shutter. Of course, various types of image processing may be executed as the image data is generated.

  The exposure start timing control unit only needs to be able to instruct the exposure start control unit to start the exposure of the light receiving sensor at the exposure start timing corresponding to the operation of the shutter blocking the light. That is, a plurality of image data indicating that the shutter is blocking light at different positions are generated with different shutter positions at the timing when each image data is captured. The data shows the operation of the shutter blocking the light. Therefore, by determining the exposure start timing so that the exposure of the light receiving element at each position of the light receiving sensor is started at the timing according to the operation, the shutter of the light receiving sensor is operated when the shutter performs the light blocking operation. It is only necessary that the exposure start timing can be adjusted so that the exposure time for each position is uniform.

  Note that a plurality of image data serving as a basis for determining the exposure start timing is photographed by a part of a plurality of light receiving elements existing on the light receiving sensor, and the part of the elements is determined by a moving direction of the shutter. Are constituted by a plurality of light receiving elements having different positions. That is, in a photographing method using both a mechanical shutter and an electronic shutter, the exposure amount becomes non-uniform along the moving direction of the mechanical shutter, and the degree of non-uniformity varies depending on conditions such as the type and position of the lens. . Therefore, if the configuration is such that a plurality of image data serving as a basis for adjusting the exposure start timing is captured by a plurality of light receiving elements having different positions in the moving direction of the shutter, the traveling characteristics of the shutter along the moving direction of the shutter are reflected. Even with a configuration that can generate a plurality of image data and uses only a part of the light receiving element on the light receiving sensor, an exposure with a uniform exposure amount for each position according to the running characteristics of the shutter It is possible to start exposure of the light receiving sensor at the start timing.

  Furthermore, it is preferable that the plurality of image data serving as the basis for determining the exposure start timing is a plurality of image data having different positions of the shadow edges of the shutter. According to this configuration, by comparing a plurality of image data, it is possible to specify a running characteristic in which the shutter moves in the moving direction of the shutter as a time change characteristic of the shadow edge position of the shutter. Therefore, by adjusting the exposure start timing based on the specified time change characteristic, it is possible to prevent the exposure amount of the light receiving sensor from becoming uneven depending on conditions such as the type and position of the lens.

  Furthermore, the exposure start timing may be adjusted so that the exposure amount at each position is made uniform according to the running characteristics of the shutter. For example, the exposure at which the shadow edge of the shutter reaches each light receiving element on the light receiving sensor. The end timing may be specified based on a plurality of image data, and the exposure of each light receiving element may be started at the exposure start timing that precedes the exposure end timing by a predetermined time. That is, since the shadow of the shutter exists on the light receiving element shielded by the shutter, the exposure on the shadow side light receiving element is completed with the shadow edge of the shutter on the light receiving sensor as a base point. Therefore, the exposure is not completed in the light receiving element opposite to the shadow. Therefore, if the manner in which the position of the shadow edge of the shutter changes with time is specified on the light receiving sensor, the exposure end timing by the shutter is specified. Therefore, if the exposure of each light receiving element is started at an exposure start timing that precedes the exposure end timing by a predetermined time, the exposure can be started at the exposure start timing according to the running characteristics of the shutter. Note that the predetermined time may be any required exposure time, and can be appropriately selected according to user settings and the like.

  Furthermore, the light receiving element for generating a plurality of image data for adjusting the exposure start timing may be a plurality of light receiving elements having different positions in the moving direction of the shutter. It is possible to adopt a configuration in which a plurality of image data indicating a state where the shutter blocks light at different positions by at least one row of light receiving elements arranged in the moving direction can be employed. According to this configuration, it is possible to specify the travel characteristics of the shutter over the entire imaging region of the light receiving sensor at least in the direction of movement of the shutter. If a plurality of light receiving elements are sufficient in one row, image data may be generated by one row of light receiving elements. However, even if image data is generated by a plurality of light receiving elements in order to perform shooting reliably. good. That is, as long as a plurality of image data can be captured at a high speed, a plurality of rows of light receiving elements may be used.

  Furthermore, a plurality of image data may be generated by operating the shutter a plurality of times, a plurality of image data may be generated while the shutter is operated once, or a combination of both. For example, the shutter is operated N times (N is an integer equal to or greater than 2), and a plurality of pieces of image data having different shutter positions are generated each time, and at the Nth time, the position of the shutter is N−1. It is possible to adopt a configuration in which a plurality of image data is generated by the image generation unit so as to be different from the position of the shutter in the second time, and the exposure start timing is determined based on the plurality of image data. That is, the shutter is operated N times, and a plurality of image data is generated each time, and the positions of the shutters are different in all of the plurality of image data generated after the N times of shutter operations. According to this configuration, it is possible to determine the exposure start timing according to the shutter operation with high accuracy based on the image data generated by a few shutter operations.

  Further, as in the present invention, the exposure start timing is based on a plurality of image data photographed by a plurality of light receiving elements that are part of the plurality of light receiving elements existing on the light receiving sensor and have different positions in the moving direction of the shutter. The method of adjusting the method can also be applied as a program or method. In addition, the apparatus, program, and method as described above may be realized as a single apparatus, or may be realized using a shared component in an apparatus having multiple functions. Is included.

It is a block diagram of an imaging device including an image generation device according to an embodiment of the present invention. (2A) is a diagram showing the position of the shutter shading edge of the shutter, the position of the edge of the shadow of the shutter, and the time change characteristics of the exposure start timing, and (2B) is a plurality of light receiving elements used when photographing image data (2C) and (2D) are schematic diagrams for explaining a state in which a plurality of image data are captured. It is a flowchart which shows an imaging | photography process.

Here, embodiments of the present invention will be described in the following order.
(1) Configuration of image generation apparatus:
(2) Shooting process:
(3) Other embodiments:

(1) Configuration of image generation apparatus:
FIG. 1 shows a photographing apparatus 1 including an image generating apparatus according to an embodiment of the present invention. The photographing apparatus 1 includes an optical system 10, a light receiving sensor 14, a storage unit 15, a display unit 20, and a recording unit 30. , An operation unit 40, an aperture adjustment unit 45, a shutter control unit 50, an exposure control unit 60, a CPU 70, and an image generation unit 80 are provided. The CPU 70 controls operations of the aperture adjustment unit 45, the shutter control unit 50, the exposure control unit 60, the storage unit 15, the image generation unit 80, the display unit 20, the recording unit 30, and the operation unit 40 according to a predetermined program.

  The optical system 10 includes a lens 11 that forms a subject image on the light receiving sensor 14, an aperture 12, and a shutter 13. In the present embodiment, the lens 11 and the diaphragm 12 are provided in a lens barrel, and the lens barrel is attached to a housing (not shown) in a replaceable manner. In the present embodiment, the lens 11 includes a plurality of lenses arranged along a direction parallel to the optical axis, but in FIG. 1, only one lens is represented for the sake of simplicity. Each lens is supported at the outer edge, and the focus position can be adjusted by allowing one or all of the lenses to move in the optical axis direction by a focus ring provided in the lens barrel. Further, it is possible to perform an optical zoom operation by making one or all of the lenses movable in the optical axis direction by a zoom ring provided in the lens barrel. That is, in this example, a manual focus lens is attached to the photographing apparatus 1. The configuration of the optical system may adopt other configurations, for example, a configuration in which the lens is configured by a liquid lens, the focal position is adjusted by deforming the lens, and an optical zoom operation is performed. Also good.

  In the present embodiment, the diaphragm 12 is constituted by a plurality of shielding plates that are rotatably supported in a plane perpendicular to the optical axis of the lens 11, and the plurality of shielding plates rotate in conjunction with each other. Thus, it is possible to change the area of the unshielded portion in a plane perpendicular to the optical axis. The aperture diameter of the aperture 12 is configured to be controlled by an aperture adjuster 45. When the aperture adjuster 45 is instructed about the aperture diameter of the aperture 12, the aperture adjuster 45 drives the aperture 12 to Set to the indicated opening diameter.

  The shutter 13 is a mechanical focal plane shutter, and includes a plurality of open / close (foldable) light shielding curtains as planar light shielding portions parallel to the light receiving sensor surface of the light receiving sensor 14. The light-shielding curtain is configured to move in a direction perpendicular to the optical axis in accordance with a control signal from the shutter control unit 50. Normally, the light-shielding curtain does not block the optical path in the direction parallel to the optical axis. Is held by. In addition, in a state where the light shielding curtain is held without blocking the light path, when a predetermined trigger is given, the state where the light shielding curtain is held without blocking the light path is released, and the light shielding curtain is moved with respect to the optical axis. Thus, the blades are driven in the vertical direction, and the plurality of blades block the optical path.

  That is, it is in a non-light-shielding state before the shutter 13 moves, and enters a light-shielding state when the movement of the shutter 13 is completed through a process in which a part of the light reaching the light receiving sensor 14 is blocked by the shutter 13. In this embodiment, after the state where the light shielding curtain of the shutter 13 is held without blocking the optical path, the time required for the light shielding curtain to stop moving after the light shielding by the light shielding curtain is completed is as follows. 3.7 milliseconds. In FIG. 1, the moving direction of the shutter 13 is indicated by a broken arrow Am.

  The light receiving sensor 14 is a CMOS (Complementary Metal Oxide Semiconductor) image sensor that includes a color filter arranged in a Bayer array and a plurality of light receiving elements (photodiodes) that accumulate charges corresponding to the amount of light for each pixel by photoelectric conversion. Of course, the light receiving sensor may be another sensor such as a CCD (Charge Coupled Device) image sensor. In the present embodiment, the light receiving sensor 14 is a sensor in which a plurality of light receiving elements are arranged in a rectangular shape, and is arranged so that the optical axis is positioned at the center of the rectangle, and one side of the rectangle is the shutter 13. Is parallel to the moving direction (Am). The other side of the rectangle is perpendicular to the moving direction (Am) of the shutter 13 and parallel to the leading portion (edge) when the shutter 13 moves.

  The light receiving sensor 14 according to the present embodiment performs a reset operation for resetting the accumulated charge corresponding to the amount of light received by the light receiving element when the exposure control unit 60 issues a reset instruction, and may start exposure at each light receiving element. it can. In addition, the light receiving sensor 14 can end the exposure by reading information indicating the amount of light received by the light receiving element when the exposure control unit 60 issues a reading instruction. Further, in the light receiving sensor 14, the start and end of these exposures can be controlled for each line or for each screen.

  Therefore, when a recording image is captured by the imaging apparatus 1 according to the present embodiment (normal imaging), the exposure time is controlled by a combination of the shutter 13 that is a mechanical shutter and the electronic shutter of the light receiving sensor 14. That is, in the case of normal shooting in the present embodiment, the exposure time is controlled by an electronic front curtain-mechanical rear curtain shutter system in which exposure is started by the electronic shutter in the light receiving sensor 14 and exposure is ended by the shutter 13. Specifically, in the case of normal shooting, exposure is started in a line-sequential manner with an electronic shutter, and the light is shielded by a mechanical shutter so that each line is shielded at the timing at which the exposure time for each line reaches a set shutter speed. Is started. When the exposure time is relatively short, the mechanical shutter operation is started before the electronic shutter operation is started and before the mechanical shutter starts to block the light hitting the light receiving sensor 14 from the start of the mechanical shutter operation. The electronic shutter operation starts. Also, when shooting image data that is the basis for adjusting the exposure start timing, exposure is started simultaneously on a plurality of light receiving elements by an electronic shutter during the light shielding operation by the mechanical shutter, and the electronic shutter is released after a predetermined time has elapsed. To end the exposure. Of course, in addition to these shooting methods, shooting is performed by various methods depending on the application. For example, in the photographing apparatus 1, it is possible to perform live view display on the display unit 20, and when photographing an image for performing the live view display, the exposure time is controlled by an electronic shutter method. That is, both the front curtain and the rear curtain are controlled by the electronic shutter.

  The operation unit 40 includes a shutter button, an operation unit for setting the aperture diameter of the aperture 12, an operation unit for setting the shutter speed, an operation unit for operating various setting menus, and a shooting mode (aperture). An operation unit for setting a priority mode and the like, and the user can give various instructions to the photographing apparatus 1 by operating the operation unit 40. In this embodiment, the stroke amount of the shutter button can be detected in two stages. That is, it is possible to distinguish and detect a state where the shutter button is half-pressed and a state where the shutter button is fully pressed. Further, in this embodiment, when the shutter button is half-pressed, it is considered that an instruction to prepare for shooting is given, and when the shutter button is fully pressed, an instruction to record an image on a recording medium is given. Considered.

  The display unit 20 includes an interface circuit (not shown), a liquid crystal panel driver, a liquid crystal panel, an eyepiece (not shown), and the like. In the present embodiment, the display unit 20 is an EVF (Electronic View Finder) that displays an image showing a subject to be photographed and allows the user to grasp information such as the state of the subject before photographing and photographing conditions. The imaging device 1 according to the embodiment is a mirrorless digital camera provided with an EVF.

  The recording unit 30 can insert a recording medium (not shown), and records information on the recording medium and reads information from the recording medium with the recording medium inserted in the recording unit 30. Can do. That is, the image data indicating the photographed image can be recorded on the recording medium. The storage unit 15 is a memory for temporarily recording image data output from the light receiving sensor 14 (information indicating the amount of light received for each light receiving element).

  The image generation unit 80 is configured by a circuit that executes various processes on image data output from the light receiving sensor 14 according to a predetermined procedure. Specifically, the image generation unit 80 acquires the image data stored in the storage unit 15 by the processing of the CPU 70, performs predetermined image processing such as γ conversion on the image data indicated by the image data, and displays the image data. And a function of generating data indicating a recording image and a recording image. Data indicating the display image is transferred to the display unit 20, and the captured image is displayed on the display unit 20. Data indicating an image for recording is transferred to the recording unit 30, and the data is recorded on a recording medium inserted into the recording unit 30.

  The image processing executed by the image generation unit 80 includes processing for outputting an evaluation value for performing AE (Automatic Exposure) processing. That is, the image generation unit 80 specifies an evaluation value (for example, an average value of luminance) for evaluating the brightness of pixels included in a predetermined photometry area set within the imaging range by the light receiving sensor 14, It is possible to output as an evaluation value for performing AE processing.

  The CPU 70 outputs a control signal to the aperture adjustment unit 45, the shutter control unit 50, and the exposure control unit 60 based on the evaluation value for performing the AE process, and sets the aperture diameter and the shutter speed of the aperture 12 so as to achieve proper exposure. adjust. That is, the CPU 70 has a function of specifying shooting conditions when shooting image data based on an instruction or default setting in the operation unit 40 and setting each unit according to the shooting conditions. Specifically, the CPU 70 specifies shooting conditions necessary for achieving proper exposure based on the evaluation value for performing the above-described AE processing, and the aperture 12 and the shutter speed are set according to the shooting conditions. A control signal is output to the aperture adjustment unit 45, the shutter control unit 50, and the exposure control unit 60. Note that the shooting conditions necessary for achieving proper exposure can be specified under various preconditions (for example, aperture priority, shutter speed priority, etc.).

  Here, the shutter speed indicates the time during which the light receiving sensor 14 is exposed to light, and the CPU 70 exposes the light receiving sensor 14 so that each line of the light receiving sensor 14 is exposed for a time corresponding to the shutter speed. Adjust the start timing. That is, in the shutter 13, which is a mechanical shutter, the running characteristics after the movement of the light-shielding curtain cannot be artificially changed. Therefore, the CPU 70 controls the exposure for each line of the light receiving sensor 14 to be constant by adjusting the exposure start timing in the light receiving sensor 14.

  When a photographing method using both a mechanical shutter and an electronic shutter is employed as in the present embodiment, the exposure amount is generally non-uniform in the moving direction of the mechanical shutter, and the degree of non-uniformity is the lens type, position, etc. It is known that it varies depending on the conditions. In other words, in an imaging method using a mechanical shutter, the optical path shielded by the mechanical shutter changes depending on the lens position (focal position, etc.). As a result, the time change characteristic in which the position of the edge of the shadow (light-shielded portion) of the mechanical shutter changes on the light receiving sensor changes. On the other hand, in the photographing method using the electronic shutter, since it operates on the light receiving sensor, the position of the edge of the light-shielded portion does not change depending on the position of the lens (focus position, etc.).

  FIG. 2A is a diagram showing an example of the time change characteristic of the position of the edge of the light shielding curtain of the shutter 13 and the time change characteristic of the position of the shadow edge of the shutter 13, where the horizontal axis is time and the vertical axis is the moving direction of the shutter. The time change characteristic of the edge position of the light shielding curtain of the shutter 13 by the broken line, the time change characteristic of the position of the shadow edge of the shutter 13 by the solid line, and the time change characteristic of the position where the exposure is started by the electronic shutter by the alternate long and short dash line Is shown. Since the light shielding curtain of the shutter 13 according to the present embodiment is driven by a spring (not shown), when the state where the light shielding curtain is held without blocking the optical path is released, the speed increases with time, and the inclination increases with time. The position of the edge of the light-shielding curtain changes with time change characteristics such as a quadratic curve indicated by a broken line in FIG.

  Comparing the position of the shadow edge of the shutter 13 on the light receiving element on the light receiving sensor 14 with the position of the edge of the light shielding curtain of the shutter 13, as shown in FIG. The position of the edge precedes and the position of the shadow edge of the shutter 13 is delayed, but eventually both are reversed.

  Therefore, in order to control the exposure time for each element of the light receiving sensor 14 to be constant, the exposure start timing is not the edge position of the light shielding curtain of the shutter 13 but the shadow edge of the shutter 13 that ends the exposure. It is necessary to change according to the change of the position. Therefore, in order to control the exposure start timing in accordance with the change in the position of the shadow edge of the shutter 13, the CPU 70 measures the time change characteristic of the position of the shadow edge of the shutter 13 before generating image data for recording. Then, the exposure start timing is adjusted in accordance with the time change characteristic (adjusting the running characteristic of the front curtain).

  In the present embodiment, the CPU 70 captures a plurality of image data indicating that the shutter 13 blocks light at different positions by a part of the light receiving elements included in the light receiving sensor 14 and sets the exposure start timing. The image is used as a basis for adjustment. FIG. 2B is a diagram schematically showing a plurality of light receiving elements used when taking an image as a basis for adjusting the exposure start timing in the present embodiment. In FIG. 2B, a broken-line rectangle indicates a shape when the light receiving sensor 14 is viewed from the optical axis direction, and a solid-line rectangle indicates a plurality of images used when photographing an image serving as a basis for adjusting the exposure start timing. The light receiving element 14a is shown. In the present embodiment, the light receiving sensor 14 is a sensor in which light receiving elements are arranged in a rectangular area, and the plurality of light receiving elements 14a used when taking an image as a basis for adjusting the exposure start timing is a light receiving sensor. It is composed of 14 light receiving elements arranged in the short direction. The plurality of light receiving elements 14 a are disposed at the center in the longitudinal direction of the light receiving sensor 14. In FIG. 2B, it is emphasized that the width of the light receiving element 14a is larger than the actual width. In this embodiment, the light receiving sensor 14 is assembled to the photographing apparatus 1 so that the short direction of the light receiving sensor 14 is parallel to the moving direction of the shutter 13. Accordingly, in the present embodiment, a plurality of light receiving elements 14 a are configured by one row of light receiving elements arranged in the moving direction of the shutter 13.

  After the shutter 13 starts moving from a state where the shutter 13 does not block the light hitting the light receiving sensor 14, the shutter 13 blocks a part of the light hitting the light receiving sensor 14 and does not block a part of the light. When image data is photographed by starting exposure at all the elements of the light receiving sensor 14 and reading out exposure amounts from the plurality of light receiving elements 14a, image data indicating that the shutter 13 blocks light is photographed. That is, in the process of blocking the light hitting the light receiving sensor 14 by the shutter 13, the shadow of the shutter 13 is projected on a part of the plurality of light receiving elements 14a arranged in the moving direction of the shutter 13, and the shadow of the shutter 13 is projected on the remaining part. Is not projected. 2B, the light receiving element on which the shadow of the shutter 13 is projected is colored black, and the light receiving element on which the shadow of the shutter 13 is not projected (the light receiving element on which light from the subject is applied). ) Is colored white. In such a state, when image data is captured, the shadow side light receiving element (the lower light receiving element shown in FIG. 2B) has been exposed with the shadow edge of the shutter 13 as the base point, and the opposite side to the shadow. In this light receiving element (the upper light receiving element shown in FIG. 2B), the exposure is not completed.

  Accordingly, when reading is started for all of the plurality of light receiving elements 14a in this state, the exposure of the plurality of light receiving elements 14a is completed, and one area is brightened with the shadow edge of the shutter 13 as a boundary as shown in FIG. 2B. An image in which the other area is dark is taken. Therefore, in the present embodiment, the CPU 70 captures image data at a plurality of timings at which the positions of the shadow edges of the shutter 13 are different, and the time change of the positions of the shadow edges associated with the operation of the shutter 13 based on the image data. It is estimated that the time change is the exposure end timing for each line in the light receiving sensor 14.

  As described above, in order to specify the temporal change in the position of the shadow edge accompanying the operation of the shutter 13, in the present embodiment, the CPU 70 performs a predetermined period (for example, a plurality of light receiving elements) in the process of operating the shutter 13 once. The process of photographing the image data a plurality of times in the shortest cycle that can be photographed by 14a is repeated N times (N is an integer of 1 or more). In the present embodiment, the description will be made on the assumption that N is 2 or more. However, when N = 1, image data is captured a plurality of times by one operation of the shutter 13, and a plurality of image data is generated. The exposure start timing is adjusted in the same manner as described above. When the operation of blocking light by the shutter 13 is repeated, the CPU 70 adjusts so that the shooting timing in the Nth shutter 13 operation process and the shooting timing in the N-13th shutter 13 operation process are shifted from each other. The shooting timing is controlled so that a plurality of image data are generated in a state where the positions of the shadow edges of the shutter 13 are different in the process of N times.

  Specifically, the CPU 70 outputs a control signal to the aperture adjusting unit 45 so that the aperture 12 is opened (maximum aperture). As a result, the aperture adjustment unit 45 opens the aperture 12. Further, the CPU 70 outputs a control signal to the shutter control unit 50 so as to perform an operation of blocking light by the shutter 13. As a result, the state where the light shielding curtain of the shutter 13 is held without blocking the light path is released, and the light blocking operation by the shutter 13 is started. When a predetermined standby time elapses after the operation of the shutter 13 is started, the CPU 70 causes the exposure control unit 60 to simultaneously use a plurality of light receiving elements 14 a that are some of the light receiving elements on the light receiving sensor 14. A control signal is output so as to start exposure. As a result, the exposure control unit 60 causes the plurality of light receiving elements 14a of the light receiving sensor 14 to perform a reset operation.

  Further, after the reset operation of the plurality of light receiving elements 14a is started and after waiting for a predetermined time, the CPU 70 outputs a control signal to the exposure control unit 60, and causes the plurality of light receiving elements 14a to output image data. Then, the CPU 70 outputs a control signal to the exposure control unit 60 so as to repeat the start of exposure and output of image data in the plurality of light receiving elements 14a at a predetermined cycle. That is, in one operation of the shutter 13, image data is photographed a plurality of times at a predetermined cycle by the plurality of light receiving elements 14a. In the present embodiment, the time required from the start to the end of the light blocking operation by the shutter 13 is longer than the predetermined period described above. Therefore, in the process in which light is blocked by the shutter 13, the generation of image data by the plurality of light receiving elements 14a is performed a plurality of times.

  When the light shielding operation of the shutter 13 is completed, the CPU 70 outputs a control signal to the shutter control unit 50 to hold the light shielding curtain of the shutter 13 again without blocking the light path. Then, a process of generating image data by the plurality of light receiving elements 14a is executed a plurality of times at a predetermined cycle in the process of performing the operation of blocking light by the shutter 13 again. However, the above-described standby time, which is the time from the start of the light shielding operation of the shutter 13 to the start of the reset operation of the plurality of light receiving elements 14a, differs depending on the number of operations of the shutter 13. That is, the standby time when the light blocking operation by the shutter 13 is performed for the first time is the first standby time, and the standby time when it is performed the second time is the second standby time different from the first standby time. The third waiting time after the first time is also set to a time different from the waiting time before that time. Then, the CPU 70 repeats this process until the light shielding operation of the shutter 13 reaches a predetermined number of times.

  As a result of the above processing, a plurality of pieces of image data shot in a state where the positions of the shadow edges of the shutter 13 are different are generated. 2C and 2D are explanatory views for explaining a state in which a plurality of image data are captured by the plurality of light receiving elements 14a so that the positions of the shadow edges of the shutter 13 are different. In FIG. FIG. 2D shows a state in which a plurality of image data is photographed during the second operation of the shutter 13.

  2C and 2D, similarly to FIG. 2B, the light receiving element on which the shadow of the shutter 13 is projected is colored black, and the light receiving element on which the shadow of the shutter 13 is not projected is colored white. . As shown in FIG. 2C and FIG. 2D, in the process in which the shutter 13 is operated once, image data is captured a plurality of times. For example, pixels corresponding to the positions of the white and black edges shown in FIG. When specified, it is possible to specify how the shadow edge of the shutter 13 moves in the moving direction of the shutter 13 over time. In addition, the time when the image data is captured can be specified from, for example, the image data capture cycle. 2C and 2D can be used to interpolate the shadow edge position of the shutter 13 during the time when shooting is not being performed, and to estimate the temporal change characteristic of the shadow edge position of the shutter 13. Note that the first standby time when shooting FIG. 2C is different from the second standby time when shooting FIG. 2D, and the second standby time is longer in the example shown in FIG. The position of the shadow edge of 13 is a position shifted upward (moving direction of the shutter 13) from the position shown in FIG. 2C.

  When a plurality of image data are generated by the above processing, the CPU 70 estimates how the position of the shadow edge of the shutter 13 changes according to time based on the plurality of image data, and receives the light receiving sensor 14. Since the exposure end timing in each element in the line is the same, the time transition of the exposure end timing in each line of the light receiving sensor 14 is estimated. Further, the CPU 70 determines the exposure start timing of each line so that the exposure time is preceded by the time corresponding to the shutter speed in each line.

  Thereafter, the process proceeds to a photographing process for generating image data of the subject. That is, the CPU 70 outputs a control signal to the exposure control unit 60 so that exposure in each line of the light receiving sensor 14 is started at the exposure start timing. As a result, the exposure control unit 60 causes the light receiving elements of each line to perform a reset operation so that the exposure is started at the above-described exposure start timing. Further, the CPU 70 outputs a control signal to the shutter control unit 50, and controls the movement start timing of the shutter 13 so that the exposure in each line ends after the time corresponding to the shutter speed has elapsed. As a result, all the light receiving elements on the light receiving sensor 14 perform photographing with substantially the same exposure time. When the movement of the shutter 13 is completed, an image of the subject is output based on the exposure amount read from the light receiving sensor 14.

  According to the above configuration, exposure is started based on a plurality of image data captured with different shutter positions and showing that the shutter blocks light at different positions. Adjust timing. For this reason, it is possible to adjust the exposure start timing in accordance with the actually measured shutter operation, and the exposure amount at each position of the light receiving sensor can be made uniform almost accurately.

  Further, the plurality of image data described above are photographed by a plurality of light receiving elements (a plurality of light receiving elements 14 a shown in FIG. 2B) configured by one row of light receiving elements arranged in the short direction of the light receiving sensor 14. Therefore, the imaging of the image data is repeated at an extremely fast period compared to the case of taking an image showing that the shutter blocks light at different positions using all the light receiving elements present on the light receiving sensor. be able to. For this reason, even if the light shielding by the shutter 13 is completed in a short period of 3.7 milliseconds as described above, a plurality of image data can be generated during the 3.7 milliseconds.

  Further, as in the present embodiment, the shutter 13 is operated a plurality of times, and a process of generating a plurality of image data in the course of each operation is repeated, thereby generating a large number of image data in a small number of shutter driving processes. be able to. Accordingly, it is possible to generate a sufficient number of image data to define the exposure start timing with high accuracy by driving the shutter 13 a few times. Furthermore, in the present embodiment, when the shutter 13 is operated a plurality of times, only the above-described standby time (first standby time, second standby time, etc.) in each operation is set to a different time, and the shutter position is different. A plurality of image data is generated. Therefore, it is possible to easily generate a plurality of image data indicating that the shutter blocks light at different positions.

  Furthermore, in the present embodiment, the time change characteristic of the position of the shadow edge of the shutter 13 is measured by actually operating the shutter 13, so that it matches the shadow edge of the shutter 13 under any conditions. The exposure start timing can be adjusted. That is, it is not necessary to acquire lens position information or the like from the lens or the like. Therefore, even when a lens or the like that cannot provide lens information to the photographing apparatus 1 is used, the exposure start timing can be adjusted in accordance with the shadow edge of the shutter 13. Further, even if the time change characteristic of the position of the shadow edge of the shutter 13 changes with time or when it changes with the environmental temperature, the time change characteristic of the state after the change is measured to measure the time change characteristic of the shutter 13. It is possible to adjust the exposure start timing in accordance with the temporal change characteristic of the position of the shadow edge.

(2) Shooting process:
Next, a photographing process in the present embodiment will be described in detail with an example. FIG. 3 is a flowchart of the photographing process. The CPU 70 normally executes processing for performing live view display on the display unit 20. That is, the CPU 70 outputs a control signal to the exposure control unit 60 to acquire an evaluation value for performing the AE process generated by the image generation unit 80 in a state where the front curtain and the rear curtain are realized by the electronic shutter. Based on the evaluation value, the aperture diameter of the diaphragm 12 and the shutter speed are controlled so that the exposure at the time of photographing the subject becomes an appropriate exposure. In this state, the CPU 70 displays the image generated by the image generation unit 80 on the display unit 20 so that live view display is performed.

  For example, when the aperture priority is given, the CPU 70 outputs a control signal to the aperture adjustment unit 45 to adjust the aperture diameter so as to be the aperture diameter of the aperture 12 set by the user. Then, the shutter speed necessary for comparing the evaluation value for performing the above-described AE processing acquired in this state with the value of the appropriate exposure range and for the evaluation value for performing the AE processing to be the value of the proper exposure range. Identify the speed. Then, the CPU 70 outputs a control signal to the exposure control unit 60 and controls the front curtain and the rear curtain of the light receiving sensor 14 with the electronic shutter so that the exposure time matches the shutter speed.

  In this state, the user adjusts the orientation of the photographing apparatus 1 so that the subject to be photographed is arranged in the field of view while visually checking the live view display on the display unit 20, and operates the manual focus lens to adjust the focus. Adjust the position and angle of view (zoom level). In the present embodiment, it is configured to instruct to actually measure the temporal change characteristic of the shadow edge of the shutter 13 by half-pressing the shutter button. In the photographing process shown in FIG. It is determined whether or not it has been half-pressed, and waits until it is determined that it has been half-pressed (step S100).

  In the photographing apparatus 1 according to the present embodiment, when the adjusted focal position and angle of view are changed, the temporal change characteristic of the shadow edge of the shutter 13 may change. Further, the shadow edge of the shutter 13 is uniform and can be specified in an image photographed using light from a bright subject. For this reason, in this embodiment, after operating the manual focus lens to adjust the focus position and the angle of view, the photographing apparatus 1 is directed toward a uniform and bright subject (for example, a uniform white subject). Thus, there is a rule for instructing to actually measure the time change characteristic of the shadow edge of the shutter 13. Therefore, the user turns the photographing apparatus 1 toward a uniform and bright subject and presses the shutter button halfway while maintaining the focus position and the angle of view in an adjusted state.

  If it is determined in step S100 that the shutter button is half-pressed, the CPU 70 starts moving the shutter 13 (step S105). That is, the CPU 70 outputs a control signal to the shutter control unit 50 to release the state where the light shielding curtain is held without blocking the light path. Next, after the standby time described above has elapsed, the CPU 70 starts exposure simultaneously with the plurality of light receiving elements 14a (step S110). That is, the CPU 70 outputs a control signal to the exposure control unit 60 to cause the plurality of light receiving elements 14a shown in FIG. 2B to perform a reset operation. As a result, the exposure by the plurality of light receiving elements 14a is started while the shutter 13 is operating.

  The standby time in step S110 is the above-described first standby time, second standby time, and the like. In this embodiment, the length increases as the number of operations of the shutter 13 corresponding to the number of loops in steps S105 to S130 increases. become longer. In the present embodiment, the first standby time is such that the first shooting is performed immediately after the shadow edge of the shutter 13 reaches the lower end of the light receiving sensor 14 (for example, the state shown in the leftmost example of FIG. 2C). It is set to.

  Next, the CPU 70 waits for a predetermined time (step S115). Here, the predetermined time is a fixed time, but the predetermined time is different for each shooting or each time the shutter 13 is operated, and a plurality of image data indicating that the shutter 13 blocks light at different positions. Can also be configured to generate. Next, the CPU 70 generates image data (step S120). That is, the CPU 70 outputs a control signal to the exposure control unit 60 and starts reading simultaneously at the plurality of light receiving elements 14a on the light receiving sensor 14, thereby terminating the exposure. As a result, image data is output from the light receiving sensor 14 to the storage unit 15. For example, in the example shown in FIG. 2C, when image data is first generated by the first shutter 13, the image data shown in the leftmost example of FIG. 2C is generated.

  Next, the CPU 70 determines whether or not the movement of the shutter 13 has been completed (step S125). That is, the CPU 70 determines whether or not the movement of the shutter 13 is stopped after the light shielding by the light shielding curtain is completed after the state where the light shielding curtain of the shutter 13 is held without blocking the light path. The determination may be performed directly or indirectly. As the former, for example, a configuration that determines that the movement of the shutter 13 is stopped by a sensor or the like can be employed. As the latter, for example, it is determined that a predetermined period (for example, a period determined in advance as a period from the start of the movement of the shutter 13 to the completion) has elapsed after the movement of the shutter 13 is started. A configuration or the like can be adopted.

  If it is not determined in step S125 that the movement of the shutter 13 has been completed, the CPU 70 repeats the processing from step S110. As a result, a plurality of image data is generated while the shutter 13 performs the light shielding operation once. On the other hand, when it is determined in step S125 that the movement of the shutter 13 has ended, the CPU 70 determines whether or not the light shielding operation of the shutter 13 has been completed a predetermined number of times (step S130). That is, it is determined whether or not steps S105 to S125 are repeated a predetermined number of times. If it is not determined in step S130 that the predetermined number of times the light shielding operation of the shutter 13 has been completed, the processes in and after step S105 are repeated. That is, the CPU 70 outputs a control signal to the shutter control unit 50, sets again the state in which the light shielding curtain of the shutter 13 is held without blocking the light path, starts the movement of the shutter 13 again, and causes the shadow of the shutter 13 to be shaded. Shoot the edges.

  When it is determined in step S130 that the predetermined number of times the light shielding operation of the shutter 13 has been completed, the CPU 70 records information on the time variation characteristics of the shadow edge of the shutter 13 in the storage unit 15 (step S135). That is, the CPU 70 estimates the movement of the shadow edge of the shutter 13 during the timing of shooting based on the standby time at each time of the repetition process of the light shielding operation by the shutter 13 by interpolation calculation, and the shadow of the shutter 13 Is estimated as a function of time. As a result, the time change characteristic as indicated by the solid line in FIG. 2A is specified. Of course, the position along the moving direction of the shutter may be specified by the coordinates of the pixel on the light receiving sensor 14 or may be a distance from a predetermined reference position (for example, from a frame around the light receiving sensor 14). The distance may be specified, and various configurations can be adopted.

  Next, the CPU 70 outputs a control signal to the display unit 20 to display on the display unit 20 that the measurement of the time change characteristic of the shadow edge of the shutter 13 has been completed (step S140). In the present embodiment, after the measurement of the time change characteristic of the shadow edge of the shutter 13 is completed, the subject is photographed by fully pressing the shutter button. Therefore, when the user recognizes that the measurement of the time change characteristic of the shadow edge of the shutter 13 is completed by the display in step S140, the user again captures the object to be imaged when the focus position and the angle of view are adjusted. The photographing apparatus 1 is pointed at the intended subject and the shutter button is fully pressed.

  The CPU 70 determines whether or not the user operation on the shutter button has changed (step S145). That is, based on the signal from the operation unit 40, the CPU 70 has changed from the state of the shutter button that is determined to be half-pressed in step S100 to the state where the shutter button is fully pressed or the state where the half-press is released. Determine whether. If it is determined in step S145 that the shutter button has changed from the half-pressed state to the released state, the CPU 70 skips the processing from step S150 and ends the shooting process.

  If it is determined in step S145 that the shutter button has changed from the half-pressed state to the fully-pressed state, the CPU 70 starts exposure in accordance with the time change characteristics of the shadow edge of the shutter 13 (step S150). That is, the CPU 70 outputs a control signal indicating the exposure start timing for each line to the exposure control unit 60, and executes a rolling shutter operation in which the light receiving sensor 14 starts exposure for each line. At this time, the CPU 70 moves the exposure start target line in the moving direction of the shutter 13 on the light receiving sensor 14, and information on the time change characteristic of the line position recorded in the storage unit 15 in step S <b> 135. Based on the above, the exposure start timing is controlled so as to coincide with the time change characteristic of the shadow edge of the shutter 13. That is, when the time change characteristic of the shadow edge of the shutter 13 is a characteristic indicated by a solid line in FIG. 2A, the solid line is time-shifted like the one-dot chain line in FIG. Start exposure. Of course, in the exposure for each line, the exposure is simultaneously started in all the pixels (all pixels on one line) arranged in the longitudinal direction of the light receiving sensor 14. Therefore, when exposure on all lines is started, exposure is started on the entire surface of the light receiving sensor 14.

  Next, the CPU 70 starts moving the shutter 13 so that the exposure time becomes the shutter speed (step S155). In other words, an evaluation value for performing the AE process generated by the image generation unit 80 is acquired, and the aperture diameter and shutter speed of the diaphragm 12 are set such that the exposure when photographing the subject is appropriate based on the evaluation value. And decide. Further, the CPU 70 outputs a control signal to the diaphragm adjusting unit 45 to control the diaphragm 12 so that the determined opening diameter is obtained.

The CPU 70 starts the exposure of the first line on the light receiving sensor 14 (T _{1 in the} example shown in FIG. 2A) and the timing at which the shadow edge of the shutter 13 reaches the first line on the light receiving sensor 14 ( In the example shown in FIG. 2A, a control signal is output to the shutter control unit 50 to start the movement of the shutter 13 so that the time between T ₂ ) and the shutter speed coincides. Therefore, when the time from the start of the movement of the shutter 13 to the start of shielding the light hitting the light receiving sensor 14 is longer than the shutter speed, the movement of the shutter 13 is started before the start of exposure. That is, the order of step S150 and step S155 is reversed. As a result, the time change characteristic of the shadow position of the shutter 13 changes as shown by the solid line in FIG. 2A, and the time that each line is exposed by the electronic front curtain by the light receiving sensor 14 and the rear curtain by the shutter 13 is received by the light receiving sensor. It is constant regardless of the position of 14.

  When the movement of the shutter 13 is completed, the CPU 70 records image data (step S160). That is, the CPU 70 outputs a control signal to the exposure control unit 60 and performs reading from all the pixels on the light receiving sensor 14. As a result, the digital value of the exposure amount of all elements of the light receiving sensor 14 is output from the light receiving sensor 14 to the storage unit 15, and the CPU 70 outputs a control signal to the image generation unit 80 and outputs it to the storage unit 15. Predetermined image processing is executed on the digital value thus recorded, and image data indicating the result is recorded on a recording medium inserted in the recording unit 30. According to the above processing, the subject can be photographed with the exposure start timing controlled in accordance with the time change characteristic of the shadow edge of the shutter 13.

(3) Other embodiments:
The above embodiment is an example for carrying out the present invention, and is a part of a plurality of light receiving elements existing on the light receiving sensor and a plurality of images taken by a plurality of light receiving elements having different positions in the moving direction of the shutter. As long as the exposure start timing is adjusted based on the image data, the following modifications may be combined as appropriate, and various other embodiments may be employed.

  For example, in the above-described embodiment, the display unit 20 is an EVF using a liquid crystal panel, but the display unit 20 is a display unit other than the EVF, for example, a display unit using a liquid crystal panel attached to the back of the photographing apparatus 1. It may be, or a system using a system other than the liquid crystal panel may be used. The photographing apparatus 1 may be a single-lens reflex camera provided with a mirror, a movie camera, or a device such as a mobile phone having a photographing function. Further, in the above-described light receiving sensor 14, the color filter is a Bayer array, but the present invention may be applied to an image generation apparatus using a sensor configured with an array other than the Bayer array. For example, the present invention may be applied to an image generation apparatus using a 3CCD or a 3-layer sensor.

  Furthermore, in the above-described embodiment, a manual focus lens is used. However, an autofocus lens is attached to the image capturing apparatus 1 and is a part of a plurality of light receiving elements existing on the light receiving sensor, and also in the moving direction of the shutter. The exposure start timing may be adjusted based on a plurality of image data captured by a plurality of light receiving elements having different positions. For example, after the focus position is automatically adjusted by the autofocus lens, the processing after step S105 shown in FIG. 3 is executed, so that the image data taken by adjusting the exposure start timing in accordance with the operation characteristics of the shutter is obtained. Can be generated.

  Further, in the above-described embodiment, the operation of actually measuring the time change characteristic of the shadow edge of the shutter 13 is started by half-pressing the shutter button, but instead is started by the user operating another button. Alternatively, an actual measurement mode may be prepared, and the user may start by fully pressing the shutter button in that mode.

  In the above-described embodiment, the measurement is performed using a plurality of light receiving elements (a plurality of light receiving elements 14a illustrated in FIG. 2B) configured by a single row of light receiving elements arranged in the short direction of the light receiving sensor 14. However, the present invention is not limited to this, and other light receiving elements such as performing measurement using a plurality of rows of light receiving elements having different positions in the longitudinal direction of the light receiving sensor 14 may be used.

Further, in the above-described embodiment, the actual measurement shooting is performed at a timing different from the actual measurement shooting in the case of the movement of the shutter 13 until the time after the shutter 13 starts moving. In addition, the measurement shooting may be performed at the same timing as the measurement shooting in the case of the movement of the shutter 13 until the time since the start of the movement of the shutter 13.
Further, a plurality of image data may be generated by repeating generation of one image data by one operation of the shutter 13 a plurality of times.

DESCRIPTION OF SYMBOLS 10 ... Optical system, 11 ... Lens, 12 ... Aperture, 13 ... Shutter, 14 ... Light receiving sensor, 14a ... Light receiving element, 15 ... Memory | storage part, 15 ... Memory | storage part, 20 ... Display part, 30 ... Recording part, 40 ... Operation 45, adjustment unit, 50 ... shutter control unit, 60 ... exposure control unit, 80 ... image generation unit

Claims (6)

A light receiving sensor that receives light passing through the lens;
A shutter that blocks the light hitting the light receiving sensor;
An exposure start controller that starts exposure by resetting the light receiving sensor at a predetermined exposure start timing;
An image generating unit that generates image data according to the amount of light received by the light receiving sensor between the start and end of the exposure;
A plurality of the image data indicating that the light is blocking the light at different positions are received by a part of the plurality of light receiving elements existing on the light receiving sensor while the shutter is moving . An exposure start timing control unit that generates the image generation unit based on the amount of light, and determines the exposure start timing based on the plurality of the image data;
An image generation apparatus comprising: The exposure start timing control unit specifies an exposure end timing at which a shadow edge of the shutter reaches each light receiving element on the light receiving sensor based on the plurality of image data, and is a predetermined time from the exposure end timing. Starting the exposure of each light receiving element at the preceding exposure start timing;
The image generation apparatus according to claim 1. The exposure start timing control unit generates a plurality of the image data based on the amount of light received by at least one row of light receiving elements arranged in the moving direction of the shutter.
The image generation apparatus according to claim 1. The exposure start timing control unit operates the shutter N times (N is an integer equal to or greater than 2), causes the image generation unit to generate a plurality of the image data having different shutter positions each time, and Determining the exposure start timing based on the image data of
The image generation apparatus according to claim 1. The exposure start timing control unit
In the Nth time, the image generation unit generates at least one image data different from the shutter position in the N-1th time until the shutter position, and the plurality of images generated by the image generation unit are generated. Determining the exposure start timing based on the data;
The image generation apparatus according to claim 4. A light receiving sensor that receives light passing through the lens;
A shutter that blocks the light hitting the light receiving sensor;
An exposure start controller that starts exposure by resetting the light receiving sensor at a predetermined exposure start timing;
An exposure start timing adjustment method in an image generation apparatus comprising an image generation unit that generates image data according to the amount of light received by the light receiving sensor between the start and end of the exposure,
A plurality of the image data indicating that the light is blocking the light at different positions are received by a part of the plurality of light receiving elements existing on the light receiving sensor while the shutter is moving . Generating the image generation unit based on the amount of light, and determining the exposure start timing based on the plurality of the image data;
Adjustment method of exposure start timing.

Images