JP5446219B2 - Photometric device - Google Patents

Description

The present invention relates to a photometric device .

2. Description of the Related Art Conventionally, as a photometric device for a camera, a technique is known in which a plurality of photoelectric conversion elements included in a photometric sensor are divided into a plurality of groups, and charge accumulation control of the photoelectric conversion elements is performed for each group (for example, Patent Document 1). ).
JP-A-6-288820

  By the way, if camera shake occurs when shooting a high-luminance subject such as a light source, the image of the light source will move in the image plane, which may or may not enter the group of photoelectric conversion elements. May occur.

  In the prior art, if such a state occurs due to camera shake, the accumulation control of the photometric sensor cannot be performed properly, and accurate photometry cannot be performed.

A photometric device as an example of the present invention includes a plurality of first charge storage sensors provided in a region corresponding to a first photometric area, and a region corresponding to a second photometric area different from the first photometric area. A photometric sensor having a plurality of second charge storage sensors, and a predetermined area included in the second photometric area adjacent to the first photometric area corresponds to the predetermined area. The first charge storage type sensor provided in the region corresponding to the first photometry area using the output of the second charge storage type sensor provided in the region and the output of the first charge storage type sensor. A calculation unit that calculates the charge accumulation time of the light, and a photometry calculation unit that calculates a photometric value using the output of the photometric sensor.

The photometric device as an example of the present invention can perform accurate photometry.

  Embodiments of the present invention will be described below. This embodiment is an embodiment of a single-lens reflex electronic camera.

  FIG. 1 is a configuration diagram of the electronic camera of the present embodiment. The electronic camera has a camera body 1 and a lens unit 2 that houses a photographing optical system.

  The camera body 1 and the lens unit 2 are each provided with a pair of mounts 9 and 10 having a male-female relationship. The lens unit 2 is attached to the camera body 1 in a replaceable manner by coupling the mount 9 on the lens unit 2 side to the mount 10 on the camera body 1 side by a bayonet mechanism or the like. The mounts 9 and 10 are each provided with an electrical contact 11. When the camera body 1 and the lens unit 2 are coupled, the electrical connection between the electrical contacts 11 is established.

  First, the configuration of the lens unit 2 will be described. The lens unit 2 includes a photographic lens 3, a lens driving unit 4, a distance detection unit 5, a diaphragm control unit 6, a diaphragm 7, and a lens side microcomputer 8. The lens driving unit 4, the distance detection unit 5, and the aperture control unit 6 are each connected to the lens side microcomputer 8.

  The photographing lens 3 is composed of a plurality of lens groups including a focus lens and a zoom lens. For simplicity, the photographing lens 3 is illustrated as a single lens in FIG.

  The lens driving unit 4 generates a lens driving signal in accordance with an instruction from the lens-side microcomputer 8, moves the photographing lens 3 in the optical axis direction to perform focus adjustment and zoom adjustment, and moves the position of the moved photographing lens 3. Is output to the lens-side microcomputer 8 and the distance detector 5.

  The distance detection unit 5 detects the distance to the subject based on information on the position of the photographing lens 3 in the optical axis direction, and outputs the detected information to the lens-side microcomputer 8.

  The diaphragm 7 adjusts the amount of light incident on the camera body 1 by opening and closing the diaphragm blades. The aperture controller 6 controls the aperture of the aperture 7 in accordance with an instruction from the lens side microcomputer 8.

  The lens side microcomputer 8 communicates with the camera side microcomputer 21 of the camera body 1 through the electrical contact 11 of the mount 9 and executes various controls in the lens unit 2. The lens-side microcomputer 8 transmits lens information (information such as the focal length and brightness (open F value) of the photographing lens 3) recorded in the ROM (not shown) of the lens unit 2 to the camera body 1. .

  Next, the configuration of the camera body 1 will be described. The camera body 1 includes a quick return mirror 12, a finder optical system (13 to 15), a photometric re-imaging lens 16, a photometric image acquisition unit 17, an imaging unit 18, a mechanical shutter 19, and a sub mirror 20. And camera circuits (21 to 32).

  The quick return mirror 12, the mechanical shutter 19, and the imaging unit 18 are arranged along the optical axis of the photographing optical system. The sub mirror 20 is disposed behind the quick return mirror 12. Further, the finder optical system (13 to 15), the photometric re-imaging lens 16, and the photometric image acquisition unit 17 are arranged on the upper part of the camera body 1.

  The quick return mirror 12 is pivotally supported by a rotation shaft (not shown) and can be switched between an observation state and a retracted state.

  The quick return mirror 12 in the observation state is inclined and disposed in front of the mechanical shutter 19 and the imaging unit 18. The quick return mirror 12 in this observation state reflects the light beam that has passed through the photographing optical system upward and guides it to the finder optical system (13 to 15). Further, the central part of the quick return mirror 12 is a half mirror, and a part of the light beam transmitted through the quick return mirror 12 is refracted downward by the sub mirror 20 and guided to the lower part of the camera body 1 for focus detection. It is burned.

  On the other hand, the retracted quick return mirror 12 is flipped upward together with the sub mirror 20 and is at a position off the photographing optical path. When the quick return mirror 12 is in the retracted state, the light beam that has passed through the photographing optical system is guided to the mechanical shutter 19 and the imaging unit 18.

  Note that the quick return mirror 14 is in an observation state at the start of the main photographing.

  The finder optical system (13 to 15) includes a diffusion screen (focus plate) 13, a condenser lens (not shown), a pentaprism 14, and an eyepiece lens 15. Among these, the pentaprism 14 is housed in a protruding portion position on the upper part of the camera body 1.

  The diffusing screen 13 is positioned above the quick return mirror 12, and the light beam reflected by the quick return mirror 12 in the observation state once forms an image. The light beam formed on the diffusing screen 13 passes through a condenser lens (not shown), is reflected inside the pentaprism 14, and is guided to an exit surface having an angle of 90 degrees with respect to the incident surface of the pentaprism 14. . The light flux from the exit surface of the pentaprism 14 reaches the eyes of the photographer through the eyepiece 15.

  The photometric re-imaging lens 16 and the photometric image acquisition unit 17 are arranged in the vicinity of the pentaprism 14. The photometric re-imaging lens 16 re-images a part of the light beam formed on the diffusion screen 13, and the photometric image acquisition unit 17 photoelectrically converts the finder image formed on the light receiving surface by the re-imaging. The analog image signal of the photometric image is generated by conversion. The photometric image acquisition unit 17 has an image sensor composed of a CCD area sensor or a CMOS area sensor.

  Here, an example of an arrangement image of photoelectric conversion elements in a sensor (photometric sensor) included in the photometric image acquisition unit 17 is shown in FIG. On the photometric sensor, a charge storage type photoelectric conversion element indicated by a symbol “e” in FIG. 2 is two-dimensionally arranged. The photometric image acquisition unit 17 can control the charge accumulation time for each photoelectric conversion element arranged on the sensor.

  In the photometric image acquisition unit 17 of the electronic camera according to the present embodiment, the charge accumulation time of the photoelectric conversion element is indicated by reference numerals “A”, “B”, “C”, and “D” in FIG. It can be controlled for each group region (area) of the upper, lower, left, and right photoelectric conversion elements.

  The imaging unit 18 is an imaging element such as a CCD area sensor or a CMOS area sensor, and generates a main captured image that is a recording image. The imaging unit 18 photoelectrically converts the subject image formed on the light receiving surface when the quick return mirror 12 is in the retracted state, and generates an analog image signal of the actual captured image.

  The mechanical shutter 19 adjusts the exposure time of the imaging unit 18 by controlling the opening and closing thereof.

  The camera circuit (21 to 32) includes a camera-side microcomputer 21, a focus detection unit 22, a shutter control unit 23, a ROM 24, a RAM 25, a recording interface (recording I / F) 26, and an A / D conversion unit 27. And an image sensor driving unit 28, an image processing unit 29, an A / D conversion unit 30, an image sensor driving unit 31, and a camera shake sensor 32. Note that these components are connected via a system bus 33. The A / D conversion unit 27 and the image sensor driving unit 28 are connected to the photometric image acquisition unit 17, and the A / D conversion unit 30 and the image sensor driving unit 31 are connected to the imaging unit 18, respectively.

  The focus detection unit 22 is disposed below the camera body 1, generates two subject images from a light beam guided by the sub mirror 20 by a separator lens (not shown), and measures the image interval with a line sensor (not shown). Then, the amount of focus shift is detected for each AF area (so-called phase difference detection method). Then, the focus detection unit 22 outputs information on the detected focus shift amount (defocus amount) to the camera-side microcomputer 21.

  The shutter control unit 23 performs opening / closing control of the mechanical shutter 19 at the time of shooting in accordance with an instruction from the camera-side microcomputer 21.

  The image sensor driving unit 28 drives the photometric image acquisition unit 17 based on an instruction from the camera-side microcomputer 21 to generate an analog image signal of the photometric image.

  Specifically, the image sensor drive unit 28 first sets the charge accumulation time of the photoelectric conversion element of the photometric image acquisition unit 17 based on an instruction (charge accumulation time setting instruction) from the camera-side microcomputer 21. This setting is performed for each of the areas “A”, “B”, “C”, and “D” of the photometric image acquisition unit 17. Next, the image sensor drive unit 28 drives the photometry image acquisition unit 17 to generate an analog image signal of the photometry image based on an instruction from the camera-side microcomputer 21 (an instruction to capture a photometry image). At this time, the photoelectric conversion element of the photometric image acquisition unit 17 outputs the photoelectric conversion charge accumulated based on the set charge accumulation time. Thereby, an analog image signal of the photometric image is generated.

  The A / D conversion unit 27 performs CDS (correlated double sampling), gain adjustment, A / D on the analog image signal of the photometric image generated by the photometric image acquisition unit 17 based on an instruction from the camera-side microcomputer 21. Analog signal processing such as conversion is performed, and the photometric image data after the processing is output to the RAM 25.

  The imaging element driving unit 31 drives the imaging unit 18 based on an instruction from the camera-side microcomputer 21 to generate an analog image signal of the actual captured image.

  The A / D conversion unit 30 performs CDS (correlated double sampling), gain adjustment, A / D conversion, and the like on the analog image signal of the actual captured image generated by the imaging unit 18 based on an instruction from the camera-side microcomputer 21. The analog signal processing is performed, and the data of the captured image after the processing is output to the RAM 25. In addition, the A / D conversion unit 30 sets an adjustment amount for gain adjustment based on an instruction from the camera-side microcomputer 21, and thereby adjusts photographing sensitivity corresponding to ISO sensitivity.

  The image processing unit 29 performs image processing such as white balance adjustment, interpolation, edge enhancement, and gamma correction on the actual captured image in the RAM 25 in accordance with an instruction from the camera-side microcomputer 21. The image processing unit 29 is configured as an ASIC or the like.

  The camera shake sensor 32 detects shaking generated in the electronic camera due to camera shake, and outputs information on the magnitude (handshake amount) and direction (handshake direction) of the shake to the camera-side microcomputer 21. Note that the camera shake sensor 32 includes an angular velocity sensor or the like.

  The RAM 25 is used and used for photometric image data output from the A / D converter 27, actual captured image data output from the A / D converter 30, and various processes executed by the camera-side microcomputer 21. Temporarily store generated data and the like.

  A connector for connecting the recording medium 34 is formed in the recording I / F 26. The recording I / F 26 accesses the recording medium 34 connected to the connector, and writes and reads image data of the actual captured image. The camera-side microcomputer 21 records the data of the captured image that has been compressed by the compression / decoding unit (not shown) or the camera-side microcomputer 21 itself on the recording medium 34 via the recording I / F 26. The recording medium 34 is a memory card incorporating a semiconductor memory, a small hard disk, or the like. The compression process is performed in JPEG (Joint Photographic Experts Group) format or the like.

  The ROM 24 stores various programs executed by the camera-side microcomputer 21 and various data necessary for the execution.

  The camera-side microcomputer 21 performs overall control of each part of the electronic camera in accordance with the content of the photographer operating an operation member (not shown). For example, when the photographer presses the release button halfway, the camera-side microcomputer 21 communicates with the lens-side microcomputer 8 so as to drive the lens drive unit 4, the distance detection unit 5, and the aperture control unit 6 of the lens unit 2. At the same time, the focus detection unit 22, the image sensor drive unit 28, and the A / D conversion unit 27 are driven via the system bus 33 to start focus detection and photometry.

  At this time, the light beam from the object field that has passed through the lens unit 2 is reflected upward by the quick return mirror 12, and passes through the diffusion screen 13, the pentaprism 14, and the photometric re-imaging lens 16 to obtain a photometric image acquisition unit. Then, a finder image that is an image of the object field is formed on the light receiving surface. Further, when a part of the light beam from the object field that has passed through the lens unit 2 is transmitted through the central portion of the quick return mirror 12 that is a half mirror, it is refracted downward by the sub mirror 20 and is focused on the lower part of the camera body 1. Guided to the detector 22.

  The focus detection unit 22 detects the defocus amount for each AF area based on the light flux from the object field guided by the sub mirror, and outputs the detected information to the camera side microcomputer 21 via the system bus 33. To do. The camera-side microcomputer 21 cooperates with the lens driving unit 4 until the focus of the AF area (selected AF area) selected by the photographer is determined based on the defocus amount information. Focus adjustment control (AF) is performed.

  The photometric image acquisition unit 17 driven via the image sensor driving unit 28 photoelectrically converts a finder image formed on the light receiving surface to generate an analog image signal of the photometric image. The A / D converter 27 performs analog signal processing on the generated image signal, and outputs the photometric image data after the processing to the RAM 25. The camera-side microcomputer 21 determines exposure conditions (shutter speed, aperture value, ISO sensitivity) based on the evaluation value calculated based on the photometric image data in the RAM 25. The evaluation value is a value indicating the brightness of the subject or the entire shooting scene and the brightness distribution of the shooting scene.

  When the photographer fully presses the release button, the camera-side microcomputer 21 performs the actual photographing by performing the exposure control of the electronic camera based on the previously determined exposure condition.

  Specifically, the camera-side microcomputer 21 drives the aperture control unit 6 through the lens-side microcomputer 8 and also flips the quick return mirror 12 in the observation state to the retracted state, and the shutter control unit 23 and the image sensor driving unit. 31, The A / D conversion unit 30 is driven to capture the actual captured image. At this time, the imaging unit 18 driven via the imaging element driving unit 31 photoelectrically converts the subject image formed on the light receiving surface to generate an analog image signal of the actual captured image. Then, the A / D conversion unit 30 performs analog signal processing on the generated image signal, and outputs data of the captured image after the processing to the RAM 25. In this way, the captured actual captured image is recorded in the RAM 25.

  When the main photographing is finished, the camera-side microcomputer 21 returns the quick return mirror 12 to the observation state again.

  Next, the camera-side microcomputer 21 drives the image processing unit 29 to perform image processing on the actual captured image in the RAM 25. The camera-side microcomputer 21 then compresses the actual captured image after the image processing, and records the compressed image on the storage medium 34 via the recording I / F 26.

  When the release button is fully pressed all at once, the camera-side microcomputer 21 performs the operation when the release button is half-pressed and the operation when the release button is fully pressed at once.

  Hereinafter, the photographing operation of the electronic camera of this embodiment will be described in detail with reference to the flowchart of FIG. 3 is executed when the release button is half-pressed by the photographer.

  Step 101: When the release button is pressed halfway by the photographer, the camera-side microcomputer 21 that has detected this operation performs the focus adjustment control (AF) operation of the photographing lens 3 described above.

  Further, the camera-side microcomputer 21 instructs the image sensor drive unit 28 to set the charge accumulation time, and each of the areas “A”, “B”, “C”, and “D” of the photometric image acquisition unit 17 Is set to the initial value.

  Step 102: The camera-side microcomputer 21 instructs the image sensor driving unit 28 to take a photometric image and takes a photometric image. Note that the photometric image generated by the photometric image acquisition unit 17 in this imaging is stored in the RAM 25.

  Step 103: The camera side microcomputer 21 calculates an evaluation value based on the photometric image data stored in the RAM 25. Then, the camera-side microcomputer 21 determines an exposure condition (shutter speed, aperture value, ISO sensitivity) based on the calculated evaluation value. The evaluation value is calculated by a known photometry method such as multi-division photometry (multi-pattern photometry), center-weighted photometry, spot photometry.

Step 104: The camera side microcomputer 21 determines whether or not the release button has been fully pressed. If the release button is not fully pressed, the camera-side microcomputer 21 proceeds to step 105 (No side), while if the release button is fully pressed, the process proceeds to step 107 (Yes side).

  Step 105: The camera-side microcomputer 21 acquires information on the amount of camera shake output from the camera shake sensor 32.

  The camera-side microcomputer 21 communicates with the lens-side microcomputer 8 to acquire information on the focal length of the photographing lens 3 recorded in the ROM (not shown) of the lens unit 2.

  Then, the camera-side microcomputer 21 determines the charge accumulation time in each area of “A”, “B”, “C”, and “D” of the photometric image acquisition unit 17, and thus the acquired camera shake amount information and focus The area expansion width is calculated based on the distance information.

  Here, the area expansion width will be described.

  If camera shake occurs when a high-luminance point light source is present near an area boundary in the object scene, the output of the photometric image acquisition unit 17 may become unstable as described above.

  For example, as shown in FIG. 4, when the charge accumulation time of each area of the photometric image acquisition unit 17 is set last time, it is assumed that the high luminance point light source exists at the “L1” position of the area “B”.

  Then, this time, when trying to determine the charge accumulation time of each area, it is assumed that camera shake occurs and the high-luminance point light source suddenly moves to the “L2” position of area “A”.

  Here, the charge accumulation time of the area “A” is set when the high brightness point light source is present at the “L1” position of the area “B”. That is, the charge accumulation time of the area “A” is set so that an optimal image signal is output on the assumption that a high-luminance point light source does not exist in the area. The charge accumulation time of area “B” is set to an appropriate value so that an optimal image signal is output in consideration of the high-intensity point light source existing at the “L1” position. Yes.

  As described above, the charge accumulation time of each area to be set this time is determined based on the output of the photoelectric conversion element in the area according to the previously set charge accumulation time. For this reason, in the area “A”, when the high-luminance point light source moves to the “L2” position due to camera shake, the output of the photoelectric conversion element corresponding to that position is saturated. Due to this saturation, even if it is attempted to determine the charge accumulation time of the area “A” this time, the appropriate value cannot be determined.

  The saturation of the output continues until the charge accumulation time of the area “A” is set to an appropriate value in consideration of the high-intensity point light source existing at the “L2” position. The output of the image acquisition unit 17 becomes unstable.

  Therefore, in order to cope with this problem, for example, when the high-intensity point light source moves as shown in FIG. 4 described above, the charge accumulation time of the area “A” is converted into, for example, the photoelectric conversion of the portion indicated by the oblique lines in FIG. The determination is made in consideration of the output of the element, that is, the sensor around the area “A”.

  In this way, in the previous setting of the charge accumulation time, the charge accumulation time of the area “A” corresponds to the position before the movement of the high luminance point light source, that is, the “L1” position of the area “B”. It is set in consideration of the output of the photoelectric conversion element.

  Therefore, in the area “A”, even if the high-luminance point light source moves to the “L2” position due to camera shake, the output of the photoelectric conversion element corresponding to the position does not saturate. This is because the charge accumulation time of the area “A” is set to an appropriate value so that an optimum image signal is output in consideration of the high luminance point light source existing at the “L1” position of the area “B”. This is because the value is set.

  Therefore, since the charge accumulation time of the current area “A” can be determined to an appropriate value, the output of the photometric image acquisition unit 17 does not become unstable.

  When the amount of camera shake is large, or when the focal length of the lens is long like a telephoto lens, the amount of movement due to camera shake of the high-luminance point light source in the object field increases. Therefore, in such a case, it is necessary to widen the range of peripheral sensors to be taken into consideration when determining the charge accumulation time of the area. In other words, a high-intensity point light source is treated as a specific photometric object, and photoelectric conversion elements that receive a light beam from the specific photometric object are included as much as possible in the range of the peripheral sensor to be considered. The range of the sensor needs to be determined.

  Thus, the area expansion width is taken into consideration when determining the charge accumulation time of each area (first charge accumulation sensor) of “A”, “B”, “C”, and “D”. It shows the range of peripheral sensors (second charge storage sensor adjacent to the first charge storage sensor).

  The area expansion width is calculated as follows based on the information on the amount of camera shake and the information on the focal length of the lens.

  When the camera shake amount is VR and the area expansion width based on the camera shake amount is ExH, ExH can be obtained by, for example, (Equation 1).

なお、（式１）中のＨｔｈ１とＨｔｈ２は、所定の閾値である。

Note that Hth1 and Hth2 in (Expression 1) are predetermined threshold values.

  As can be seen from (Expression 1), the value of ExH increases as the value of VR increases. That is, if the camera shake amount is large, the area expansion width based on the camera shake amount is widened.

  Further, assuming that the focal length of the lens is Fc and the area expansion width based on the focal length is ExF, ExF can be obtained by, for example, (Expression 2).

なお、（式２）中のＦｔｈは、所定の閾値である。

Note that Fth in (Expression 2) is a predetermined threshold value.

  As can be seen from (Expression 2), when the value of Fc is large, the value of ExF also increases. That is, if the focal length of the lens is long, the area expansion width based on the focal length is widened.

  Then, based on ExH and ExF obtained in (Expression 1) and (Expression 2), the area expansion width (Exp) is calculated by, for example, (Expression 3).

なお、Ｅｘｐ（エリア拡張幅）の単位は画素である。

Note that the unit of Exp (area expansion width) is a pixel.

  In this way, the camera side microcomputer 21 calculates the area expansion width.

  Step 106: The camera-side microcomputer 21 sets the charge accumulation time set this time for each of the areas “A”, “B”, “C”, and “D” of the photometric image acquisition unit 17 in the vicinity of the area. This is determined in consideration of the output of the photoelectric conversion element existing in the range of the sensor, that is, the calculated area expansion width.

  Specifically, the camera-side microcomputer 21 expands the range of each area of “A”, “B”, “C”, “D” of the photometric image acquisition unit 17 by the calculated area expansion width, The expanded areas are treated as “A ′”, “B ′”, “C ′”, and “D ′”, respectively.

  Here, with regard to the areas “A” and “B” of the photometric image acquisition unit 17, the image of the area “A ′” and the area “B ′” after expansion when the area expansion width is 0 to 2 pixels. Is shown in FIG.

  (A-1) in FIG. 6 shows the range of the area “A ′” after expansion when the area expansion width is 0 pixel for the area “A”. Further, (a-2) and (a-3) in FIG. 6 show the range of the area “A ′” after expansion when the area expansion width is 1 pixel and 2 pixels, respectively, for the area “A”. Yes.

  FIG. 6B-1 shows the range of the area “B ′” after expansion when the area expansion width is 0 pixel for the area “B”. Also, (b-2) and (b-3) in FIG. 6 show the range of the area “B ′” after expansion when the area expansion width is 1 pixel and 2 pixels, respectively, for the area “B”. Yes.

  Based on the output of the photoelectric conversion element in each of the areas “A ′”, “B ′”, “C ′”, and “D ′” after the expansion, the camera side microcomputer 21 performs “A”, “B”, The charge accumulation time set this time is determined for each of the areas “C” and “D”.

  At this time, in each of the expanded “A ′”, “B ′”, “C ′”, and “D ′” areas, the output of the photoelectric conversion element corresponding to the brightest part in the area is not saturated. For example, the charge accumulation time is determined so as to be 80% of the saturation output level of the photoelectric conversion element.

  That is, the output 80% of the saturation output level of the photoelectric conversion element is set as the target output V0.

  Here, the output of each photoelectric conversion element is V1 [h, v], and the charge accumulation time when obtaining the photoelectric conversion element output is T1 [h, v]. Then, the output (S1 [h, v]) per unit time of charge accumulation of the photoelectric conversion element can be obtained by, for example, (Expression 4). Note that h and v are pixel addresses.

そして、拡張後のエリア［ｉ’］（ｉ’＝Ａ’〜Ｄ’）内において最大となるＳ１［ｈ，ｖ］をＰ１［ｉ’］とすると、今回設定する電荷蓄積時間（Ｔ２［ｉ］）は、例えば（式５）によって求めることができる。

Then, assuming that S1 [h, v] that is maximum in the expanded area [i ′] (i ′ = A ′ to D ′) is P1 [i ′], the charge accumulation time (T2 [i] set this time). ]) Can be obtained by, for example, (Equation 5).

カメラ側マイコン２１は、このようにして求めた値（Ｔ２［ｉ］）を、今回設定する電荷蓄積時間として決定する。

The camera-side microcomputer 21 determines the value (T2 [i]) thus obtained as the charge accumulation time set this time.

  The camera-side microcomputer 21 instructs the image sensor drive unit 28 to set the charge accumulation time, and determines the charge accumulation times for the areas “A” to “D” of the photometric image acquisition unit 17 as described above. According to the obtained value, that is, (Equation 4), T2 [A] to T2 [D] are set.

  After setting the charge accumulation time for all areas, the camera-side microcomputer 21 proceeds to Step 102. As a result, each of the areas “A”, “B”, “C”, and “D” of the photometric image acquisition unit 17 takes into account the charge accumulation time set this time, that is, the output of sensors around the area. Thus, charge accumulation control is performed based on the determined charge accumulation time.

  Step 107: The camera side microcomputer 21 performs exposure control by controlling the exposure of the electronic camera under the exposure condition determined in Step 103.

  When the main photographing is finished, the camera-side microcomputer 21 finishes the processing of this flow.

(Supplementary items of this embodiment)
In step 105, information on the amount of camera shake and information on the focal length of the photographing lens 3 are acquired in order to calculate the area expansion width. However, when information cannot be acquired, predetermined values may be used as the information.

  In the above description, the area expansion width is calculated according to (Expression 1) to (Expression 3). However, the calculation method is not limited to this.

  For example, the relationship between the amount of camera shake, the focal length of the lens, and the area expansion width that is optimal for them is obtained in advance by experiments or the like, and the obtained relationship information is stored in a memory such as the ROM 24 as a table or the like. Keep it. Then, the area expansion width may be calculated using the table. Alternatively, the relationship obtained in advance by experiments or the like may be stored as a function in a memory such as the ROM 24, and the area expansion width may be calculated using the function.

  Further, in the above, the area expansion width is calculated based on the information on the camera shake amount and the information on the focal length of the lens, and “A”, “B”, The range of each area of “C” and “D” was expanded. However, when extending the range of each area, information on the camera shake direction output from the camera shake sensor 32 may be considered.

  In this case, if it can be determined from the information on the camera shake direction that the camera shake in the vertical direction has occurred, for example, as shown in FIG. The sensor range is expanded by the calculated area expansion width. Further, as shown in FIG. 7B, in the area “C”, the range of the upper sensor among the surrounding sensors is expanded by the calculated area expansion width.

  On the other hand, when it can be determined from the information on the camera shake direction that the camera shake in the left-right direction has occurred, for example, as shown in FIG. The range is expanded by the calculated area extension width. Further, as shown in FIG. 7 (4), in the area “D”, the range of the right sensor among the surrounding sensors is expanded by the calculated area expansion width.

  In the above description, the calculation is based on the information on the amount of camera shake and the information on the focal length of the lens regardless of the position on the sensor (photometric sensor) of the photometric image acquisition unit 17. The area expansion width thus applied is uniformly applied to all areas “A”, “B”, “C”, and “D” of the photometric image acquisition unit 17 to expand the range of each area.

  However, the position of the high brightness point light source on the photometric sensor is detected, and the information on the detected position and the information on the direction and amount of camera shake output from the camera shake sensor 32 are used. The moving range of the high-luminance point light source may be obtained, and the area expansion width calculated only for the area corresponding to the moving range portion may be applied.

  For example, as shown in FIG. 4, when the high brightness point light source moves from the “L1” position of the area “B” to the “L2” position of the area “A”, the area “A” and the area “B” are high. It is obtained as the moving range of the luminance point light source. Therefore, in this case, the area expansion width is applied to the areas “A” and “B”.

  In addition, you may make it obtain | require the information of the movement range of a high-intensity point light source on a photometry sensor using the conventional movement prediction technique.

  In addition, the information on the area extension width is not used, and the position of the high brightness point light source on the photometric sensor is detected so that the detected position is adjacent to the area to which the detected position belongs and from the position of the high brightness point light source. You may make it expand the range of the other area where distance is near to the area containing the present position where a high-intensity point light source exists. Note that whether or not the distance between the high-luminance point light source and another area is close is determined based on a predetermined threshold.

  In addition, according to the prediction using the conventional movement prediction technique, for example, it is expected that the high-intensity point light source existing in the area “B” has moved to the area “A” when the next charge accumulation time is determined. In this case, only the range of the area “A” may be expanded to include the current position where the high brightness point light source of the area “B” exists. However, the expansion of this range is performed based on the range of the area “A” and the current position where the high-intensity point light source of the area “B” exists without using the information of the area expansion width. . Then, the charge accumulation time determined based on the output of the photoelectric conversion element in the expanded area “A ′” is set as the charge accumulation time of the current area “A”. As a result, even when a high-intensity point light source exists in the area “A” when the next charge accumulation time is determined, the output of the photoelectric conversion element corresponding to the high-intensity point light source in the area “A” is saturated. There is no.

  In the above description, the areas of the sensors (photometric sensors) included in the photometric image acquisition unit 17 are described as four areas “A”, “B”, “C”, and “D”. It is not limited to.

  In the above, the exposure value is calculated based on the photometric image generated by the photometric image acquisition unit 17 and the exposure conditions (shutter speed, aperture value, ISO sensitivity) are determined based on the evaluation value. Control was performed. The photometric image is an image generated by the photometric image acquisition unit 17 by the charge accumulation control based on the charge accumulation time determined in consideration of the outputs of the surrounding sensors.

  However, the photometric image generated by the photometric image acquisition unit 17 by the above processing can be used not only for exposure control but also for example in white balance processing and focus detection calculation.

  For example, when used in white balance processing, the color temperature of the ambient light of the object scene is calculated based on the photometric image, and white balance processing is performed on the actual captured image based on the color temperature. . In this case, the photoelectric conversion element of the sensor (photometric sensor) included in the photometric image acquisition unit 17 is configured to be able to output an image signal including three color components of RGB, and thereby the object field. It is desirable to handle color information as well as luminance information.

  When used in the focus detection calculation, the focus detection calculation is performed by detecting the position of the main subject in the shooting screen based on the photometric image.

  Then, even when the high-luminance point light source moves between areas of the photometric sensor due to camera shake, white balance processing and focus detection calculation can be performed accurately.

(Operational effect of this embodiment)
As described above, in the electronic camera according to the present embodiment, the area expansion width is calculated based on the information on the amount of camera shake acquired from the camera shake sensor and the information on the focal length of the lens acquired from the lens unit. Here, the area expansion width indicates a range of peripheral sensors to be considered when determining the charge accumulation time of each area “A” to “D” of the photometric sensor. When the amount of camera shake is large or when the focal length of the lens is long, the area expansion width, that is, the range of surrounding sensors becomes wider.

  Further, the range of each area “A” to “D” of the photometric sensor is expanded by the calculated area expansion width, and the photoelectric conversion elements in the respective areas “A ′” to “D ′” after expansion are expanded. Based on the output, the charge accumulation time set for each of the areas “A” to “D” is determined.

  The charge accumulation time determined in this way is present in the range of the area extension width calculated based on the sensors around each of the areas “A” to “D”, that is, the information on the shake amount and the information on the focal length. This is determined in consideration of the output of the photoelectric conversion element.

  Then, the charge accumulation time in each of the areas “A” to “D” of the photometric sensor is set to the value determined as described above. With this setting, charge accumulation control is performed on each of the areas “A” to “D” of the photometric sensor based on the charge accumulation time determined in consideration of the outputs of the sensors around the area. .

  For example, it is assumed that a high-luminance point light source existing in the area “B” suddenly moves into the area “A” due to camera shake when determining the current charge accumulation time.

  However, since the charge accumulation time of the area “A” is set in consideration of the output of the photoelectric conversion element when the high brightness point light source exists in the area “B”, the area of the area “A” is moved by the movement of the high brightness point light source. The output of the photoelectric conversion element “A” is never saturated.

  Therefore, since the charge accumulation time of the current area “A” can be determined to an appropriate value, the output of the photometric sensor does not become unstable.

  Therefore, in the electronic camera of this embodiment, accurate photometry can be performed even when the high-luminance point light source moves between areas of the photometric sensor due to camera shake.

  In the electronic camera of the present embodiment, the calculated area extension width is a small value when the camera shake amount acquired from the camera shake sensor is small, and the calculated area extension width when the acquired camera shake amount is large. Is a large value. That is, the range of peripheral sensors to be taken into account when determining the charge accumulation time of each area “A” to “D” of the photometric sensor is changed according to the acquired amount of camera shake.

  Therefore, in the electronic camera of this embodiment, accurate photometry can be performed even when the amount of movement between areas of the high brightness point light source varies depending on the degree of camera shake.

  Further, in the electronic camera of the present embodiment, when the focal length of the lens acquired from the lens unit is short, the calculated area extension width is a small value, and when the acquired focal length of the lens is long, it is calculated. The area expansion width is large. That is, the range of peripheral sensors to be taken into account when determining the charge accumulation time of each area “A” to “D” of the photometric sensor is changed according to the focal length of the lens.

  Therefore, the electronic camera of this embodiment can perform accurate photometry even when the focal length of the lens changes.

  Further, in the electronic camera of the present embodiment, when the information on the direction of camera shake acquired from the camera shake sensor indicates the vertical direction, when determining the charge accumulation time of each area “A” to “D” of the photometric sensor The range of surrounding sensors to be added to is expanded in the vertical direction. On the other hand, when the acquired information on the camera shake direction indicates horizontal, the range of peripheral sensors to be taken into account when determining the charge accumulation time of each area “A” to “D” of the photometric sensor Is spread laterally.

  Therefore, in the electronic camera of this embodiment, accurate photometry can be performed even if the moving direction between areas of the high-intensity point light source due to camera shake changes.

  Further, in the electronic camera of the present embodiment, the position of the high brightness point light source on the photometric sensor is detected, and based on the information on the detected position and the information on the shake direction and the shake amount output from the shake sensor. A moving range of the high-intensity point light source on the photometric sensor is obtained. Then, the area expansion width calculated only for the area corresponding to the moving range portion is applied. In this case, the area range is expanded only to the area corresponding to the moving range portion.

  Further, in the electronic camera of the present embodiment, the position of the high brightness point light source on the photometric sensor is detected, and the distance from the position of the high brightness point light source is adjacent to the area to which the detected position belongs. The range of the area is expanded to include the current position where the high-intensity point light source exists. In this case, the range of the area is expanded only in the area where the distance from the position where the high luminance point light source is present is short.

  Further, in the electronic camera of the present embodiment, when it is predicted that a high-intensity point light source existing in a certain area is moving to another area when determining the next charge accumulation time, the other Only the area of this area is expanded to include a position in the current area where the high-luminance point light source exists. In this case, the area range is expanded only to the area where the high-luminance point light source is expected to be moved.

  As described above, in the electronic camera of this embodiment, only the area related to the movement of the high brightness point light source is expanded, so that accurate photometry can be performed.

It is a block diagram of a single-lens reflex type electronic camera in which the photometric device of the present invention is incorporated. It is a figure which shows the example of the arrangement image of the photoelectric conversion element in a photometry sensor. It is a flowchart which shows operation | movement of imaging | photography of an electronic camera. It is a figure explaining the movement between areas by hand-shake of a high-intensity point light source. It is a figure explaining the sensor around area "A". It is a figure which shows the range of area "A '" and area "B'" after expansion. It is a figure explaining the sensor of the periphery of each area in the case of considering the information on a camera shake direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Camera body, 2 ... Lens unit, 3 ... Shooting lens, 4 ... Lens drive part, 5 ... Distance detection part, 6 ... Aperture control part, 7 ... Aperture, 8 ... Lens side microcomputer, 9 ... Mount, 10 ... Mount 11 ... Electric contact, 12 ... Quick return mirror, 13 ... Diffusion screen (focal plate), 14 ... Pental prism, 15 ... Eyepiece lens, 16 ... Reimaging lens for photometry, 17 ... Image acquisition unit for photometry, 18 ... Image pickup unit, 19 ... mechanical shutter, 20 ... sub mirror, 21 ... camera side microcomputer, 22 ... focus detection unit, 23 ... shutter control unit, 24 ... ROM, 25 ... RAM, 26 ... recording interface (recording I / F), 27 A / D converter, 28 ... Image sensor drive unit, 29 ... Image processor, 30 ... A / D converter, 31 ... Image sensor drive unit, 32 ... Camera shake sensor, 33 ... System bus, 4 ... recording medium

Claims (7)

A plurality of first charge storage sensors provided in a region corresponding to the first photometry area, and a plurality of second charge storage sensors provided in a region corresponding to a second photometry area different from the first photometry area. A photometric sensor having
An output of the second charge storage sensor provided in a region corresponding to the predetermined area when a high-luminance subject is included in a predetermined area close to the first photometric area and included in the second photometric area; and A calculation unit for calculating a charge accumulation time of the first charge accumulation type sensor provided in an area corresponding to the first photometry area using an output of the first charge accumulation type sensor;
A photometric calculator that calculates a photometric value using the output of the photometric sensor;
A photometric device comprising: The photometric device according to claim 1,
The calculation unit is configured to prevent the output of the second charge storage sensor provided in a region corresponding to the predetermined area and the output of the first charge storage sensor from being saturated. A photometric device characterized by calculating a charge accumulation time . In the photometric device according to claim 1 or 2,
The arithmetic unit does not use the output of the second charge storage type sensor provided in a region corresponding to the outside of the predetermined area, and the first charge storage type provided in a region corresponding to the first photometry area. A photometric device characterized by calculating a charge accumulation time of a sensor . In the photometry apparatus as described in any one of Claims 1-3,
A shake detection unit for detecting the shake of the device;
And a setting unit configured to set the predetermined area so that the predetermined area becomes wider as the shake detected by the shake detection unit is larger . In the photometry apparatus as described in any one of Claims 1-3,
A focal length detection unit for detecting a focal length;
And a setting unit that sets the predetermined area so that the predetermined area becomes wider as the focal length detected by the focal length detection unit is longer. The photometric device according to claim 4,
A focal length detection unit for detecting the focal length;
The photometric device according to claim 1, wherein the setting unit sets the predetermined area so that the predetermined area becomes wider as the focal length detected by the focal length detection unit is longer. In the photometry apparatus as described in any one of Claims 1-6,
The photometric device according to claim 1, wherein the high brightness subject has higher brightness than the subject included in the first photometry area.

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