JP2012008442A - Exposure controller and exposure control method - Google Patents

Abstract

An exposure control apparatus controls a target exposure value with high responsiveness and high accuracy in a wide exposure adjustment range.
An exposure control device controls exposure within an exposure adjustment range ER by a plurality of exposure adjustment units using an exposure evaluation value EV (pv) and an exposure target value EV (sp) based on a luminance signal. A deviation EV (err) between the exposure target value EV (sp) and the exposure evaluation value EV (pv) is obtained, and the exposure is controlled in a steady state where the deviation EV (err) is equal to or less than a predetermined value and within the gain exposure control range ER-g. The gain exposure adjustment unit 62 controls the exposure with the main control amount Ci-m, and the aperture correction amount Ci-s of the aperture exposure adjustment unit 61 is also added.
[Selection] Figure 5

Description

  The present invention relates to a camera exposure control apparatus and exposure control method for automatically adjusting exposure.

  Many still cameras and video cameras have a so-called automatic exposure function that automatically adjusts the exposure. As such an automatic exposure function, for example, by switching a plurality of exposure adjustment units according to the brightness of the subject, it corresponds to a wide exposure adjustment range, and an evaluation value calculated from a luminance value of a photographed image is an exposure target value. A mechanism for feedback control is known (see Patent Documents 1 and 2). As a plurality of exposure adjustment units, there are an aperture exposure adjustment unit that reduces the amount of light passing through the lens, a gain exposure adjustment unit that amplifies the signal from the image sensor, and an electronic shutter adjustment unit that changes the accumulation time of charges accumulated in the image sensor. It is used.

  However, in the configuration using a plurality of conventional exposure adjustment units, the characteristics of each exposure adjustment unit cannot be fully utilized, that is, in a wide exposure adjustment range corresponding to the brightness of the subject, high responsiveness and There was a problem that it was difficult to control the target exposure value with high accuracy.

JP 2004-129025 A JP2003-241248

  In light of solving the above-described problems of the conventional techniques, the present invention provides a simple exposure control apparatus and exposure control method capable of controlling a target exposure value with high responsiveness and high accuracy in a wide exposure adjustment range. The purpose is to provide a simple configuration.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

[Application Example 1]
Application Example 1 is an imaging device that captures an image of a subject and outputs a video signal including a luminance signal, an exposure evaluation value calculated based on the luminance signal, and an exposure target value that is a target exposure for the exposure evaluation value. A first exposure adjustment unit that performs exposure adjustment, and an exposure control unit that controls exposure by a second exposure adjustment unit that performs exposure adjustment at a lower exposure resolution speed and lower resolution than the first exposure adjustment unit. An exposure control device comprising:
The exposure control means includes
An exposure area setting unit that sets an exposure adjustment range in which exposure is adjusted according to the luminance signal divided into a first exposure control range and a second exposure control range;
An exposure control amount setting unit that sets an exposure control amount that can be adjusted by the first exposure adjustment unit to a main adjustment amount and a correction amount;
A deviation between the exposure target value and the exposure evaluation value is obtained, and when the deviation is equal to or less than a predetermined value and exposure control is performed in the second exposure control range, in addition to exposure control by the second exposure adjustment unit An exposure correction control unit in which the first exposure adjustment unit controls exposure with the correction amount;
It is provided with.

  In the exposure control apparatus according to the application example 1, the first exposure adjustment unit and the first exposure adjustment unit are used by using the exposure evaluation value and the exposure target value calculated based on the luminance signal from the imaging element that images the subject. Exposure control is performed by the second exposure adjustment unit having a higher exposure adjustment speed and lower resolution. Such exposure control is performed by the first and second exposure adjustment units by dividing the exposure adjustment range corresponding to the brightness of the subject into a first exposure control range and a second exposure control range. In the first exposure adjustment unit, an exposure adjustment amount that can be adjusted is divided into a main adjustment amount and a correction amount. When the exposure target value is in the second exposure control range and the deviation between the exposure target value and the exposure evaluation value is a steady state equal to or less than a predetermined value, in addition to the exposure control by the second exposure adjustment unit, the first exposure adjustment unit Controls the exposure with the correction amount. Therefore, in the second exposure control range, in addition to the exposure control by the second exposure adjustment unit having a low resolution, the exposure control by the first exposure adjustment unit having a high resolution is also performed. To converge.

[Application Example 2]
The first and second exposure adjustment units of Application Example 2 are stored in the aperture exposure adjustment unit that controls the amount of light to the image sensor, the gain exposure adjustment unit that amplifies the video signal of the image sensor, or the image sensor. A configuration that is one of electronic shutter adjustment units that change the charge accumulation time can be employed.

[Application Example 3]
Application Example 3 uses the exposure evaluation value calculated based on the luminance signal from the image sensor that images the subject and the exposure target value that is the target exposure for the exposure evaluation value to perform the first exposure adjustment. In an exposure control method in which exposure is controlled by an adjustment unit, and a second exposure adjustment unit that performs exposure adjustment at a lower exposure resolution speed and lower resolution than the first exposure adjustment unit,
An exposure adjustment range in which exposure adjustment is performed according to the luminance signal is set separately for a first exposure control range and a second exposure control range,
The exposure control amount that can be adjusted by the second exposure adjustment unit is set separately for the main adjustment amount and the correction amount,
A deviation between the exposure target value and the exposure evaluation value is obtained, and when the deviation is equal to or less than a predetermined value and exposure control is performed in the second exposure control range, in addition to exposure control by the second exposure adjustment unit The exposure control method is characterized in that the first exposure adjustment unit controls the exposure with the correction amount.

It is explanatory drawing which shows schematic structure of the video camera provided with the exposure control apparatus concerning the Example of this invention. It is a block diagram explaining the exposure control apparatus of the video camera with which the microcomputer was equipped. It is explanatory drawing explaining the relationship between the exposure control amount at the time of using a some exposure adjustment part, and an exposure adjustment range. It is explanatory drawing explaining the time change of the exposure value by an exposure adjustment part. It is explanatory drawing explaining an exposure control process. It is a flowchart explaining the response area | region determination process performed with a microcomputer. It is a flowchart explaining a transient state exposure value distribution process. It is a flowchart explaining a steady state exposure value distribution process. It is explanatory drawing explaining the exposure control process in an aperture exposure control range. It is explanatory drawing explaining the exposure control process in a gain exposure control range.

  Hereinafter, in order to further clarify the operations and effects of the present invention described above, embodiments of the present invention will be described based on examples in the following order.

(1) Configuration of video camera:
FIG. 1 is an explanatory diagram showing a schematic configuration of a video camera 10 as an embodiment of the present invention. As shown in the figure, the video camera 10 includes a lens unit 20, an imaging device 30, an AGC circuit 32, an image processing DSP (Digital Signal Processor) 34, and a microcomputer 40.

  The lens unit 20 adjusts the amount of light transmitted through the unit, a first lens 21 fixed in the unit, a zoom lens 22 that moves in the direction of the optical axis and performs a magnification operation, in order from the foreground on the subject side. An iris mechanism 23, a third lens 24 fixed in the unit, and a focus lens 25 that moves in the optical axis direction and adjusts the focal position. In the inner focus type lens unit, the zoom lens may be referred to as a variator lens, and the focus lens may be referred to as a compensator lens.

  Connected to the zoom lens 22 is a zoom motor 22M having a lead screw that moves the zoom lens 22 forward or backward in the optical axis direction. The zoom motor 22M is a stepping motor, and is connected to the microcomputer 40 via a zoom driver 22D that drives the zoom motor 22M. Therefore, the zoom lens 22 can move in the lens unit 20 in the direction of the optical axis in accordance with the number of steps specified by the microcomputer 40, and can perform a zooming operation.

  The focus lens 25 is connected to a focus motor 25M having a lead screw that moves the focus lens 25 forward or backward in the optical axis direction. The focus motor 25M is a stepping motor, and is connected to the microcomputer 40 via a focus driver 25D that drives the focus motor 25M. Therefore, the focus lens 25 can move in the lens unit 20 in the direction of the optical axis in accordance with the number of steps designated by the microcomputer 40 and adjust the focal position.

  An iris motor 23M that adjusts the iris of the iris mechanism 23 is connected to the iris mechanism 23. The iris motor 23M is a galvanometer, and is connected to the microcomputer 40 via an iris driver 23D that drives the iris motor 23M. Therefore, the iris mechanism 23 can adjust the amount of light transmitted through the lens unit 20 in accordance with an instruction from the microcomputer 40. In this embodiment, the zoom motor 22M and the focus motor 25M are stepping motors, and the iris motor 23M is a galvanometer. However, other types of motors such as a DC motor may be used.

  As described above, the zoom lens 22 and the focus lens 25 move in the lens unit 20 in the optical axis direction. Therefore, the lens unit 20 includes a first origin sensor 22S and a second origin sensor 25S in order to detect whether or not these lenses have moved to the origin, which is a predetermined reference position. The first origin sensor 22S and the second origin sensor 25S are configured by photo interrupters and are connected to the microcomputer 40. The iris mechanism 23 is driven to adjust the diaphragm by changing the opening area. For this reason, an iris position sensor 23S is provided to detect the aperture amount, and is connected to the microcomputer 40.

  The image sensor 30 is an image sensor that receives light transmitted through the lens unit 20 and converts the light into an electrical signal. The AGC circuit 32 is a circuit that receives an electrical signal output from the image sensor 30 and amplifies the output of the electrical signal to an appropriate output. The image processing DSP 34 receives an electrical signal from the AGC circuit 32 and performs A / D conversion on the signal to generate image data. The image processing DSP 34 converts the image data generated in this way into a composite video signal or an S video signal, and outputs this to an external device such as a television monitor or a recording device via the output terminal 36. Further, the image processing DSP 34 has a function of extracting a luminance signal from the image data generated by A / D conversion and outputting it to the microcomputer 40. In addition, the image processing DSP 34 has a function of performing various image processing such as gamma correction, aperture correction, and white balance adjustment on the image data.

  FIG. 2 is a block diagram for explaining an exposure control device of the video camera 10 provided in the microcomputer 40. The exposure control device uses the exposure evaluation value EV (pv) created based on the luminance signal output from the image processing DSP 34 (FIG. 1), the set value by the user, and the exposure target set by the microcomputer 40. The value EV (sp) is input and feedback control is performed so that those errors are minimized. The exposure value calculation unit 51, the exposure value distribution unit 52, and the aperture exposure adjustment unit 61 (first according to the present invention). An exposure adjustment unit), a gain exposure adjustment unit 62 (second exposure adjustment unit according to the present invention), and an electronic shutter adjustment unit 63.

  The exposure value calculation unit 51 inputs a deviation EV (err) obtained from the difference between the exposure target value EV (sp) and the exposure evaluation value EV (pv), and sets the deviation EV (err) to zero. C is calculated, that is, an exposure control amount C for which the exposure evaluation value EV (pv) converges to the exposure target value EV (sp) is calculated. Based on the exposure control amount C and the exposure evaluation value EV (pv) output from the exposure value calculation unit 51, the exposure value distribution unit 52 sends the aperture exposure control amount Ci and gain exposure adjustment unit 62 to the aperture exposure adjustment unit 61. The gain exposure control amount Cg to be sent to and the shutter exposure control amount Cs to be sent to the electronic shutter adjustment unit 63 are calculated. The aperture exposure adjustment unit 61 is a mechanism configured by the iris driver 23D, the iris motor 23M, and the iris mechanism 23 described above, and opens and closes the aperture of the iris mechanism 23 by the aperture exposure control amount Ci from the exposure value distribution unit 52. Adjust the exposure value. The gain exposure adjustment unit 62 adjusts the exposure value by increasing / decreasing the output level of the image sensor 30 according to the gain exposure control amount Cg from the exposure value distribution unit 52. The electronic shutter adjustment unit 63 adjusts the exposure value by increasing / decreasing the charge accumulation time of the image sensor 30 according to the shutter exposure control amount Cs from the exposure value distribution unit 52.

  FIG. 3 is an explanatory diagram for explaining the relationship between the exposure control amount C and the exposure adjustment range ER when a plurality of exposure adjustment units are used. Here, as shown in FIG. 2, a case where an aperture exposure adjustment unit 61, a gain exposure adjustment unit 62, and an electronic shutter adjustment unit 63 are used as a plurality of exposure adjustment units will be described. The exposure adjustment range ER is divided into four ranges according to the brightness of the subject, that is, the low-speed shutter exposure control range ER-sL, the gain exposure control range ER-g, the aperture exposure control range ER-i, and the high-speed shutter. It is divided into an exposure control range ER-sH.

  The low-speed shutter exposure control range ER-sL is a range in which exposure is adjusted by the electronic shutter adjustment unit 63 when the subject is in the darkest state, and is controlled by the shutter exposure control amount Cs, that is, charge accumulation of the electronic shutter adjustment unit 63. It is adjusted by changing the time longer than the time of one frame. At this time, the gain exposure control amount Cg by the gain exposure adjustment unit 62 is at the maximum value, and the aperture exposure control amount Ci by the aperture exposure adjustment unit 61 is fully open.

  The gain exposure control range ER-g is a range in which the exposure is mainly adjusted by the gain exposure adjustment unit 62 when the subject is relatively dark, and controls the gain exposure control amount Cg, that is, increases or decreases the gain of the video signal. In addition, in a steady state to be described later, the aperture exposure adjustment unit 61 makes a secondary adjustment with the aperture correction amount Ci-s. At this time, in the electronic shutter adjustment unit 63, the shutter exposure control amount Cs is a constant value.

  The aperture exposure control range ER-i is a range in which exposure is mainly adjusted by the aperture exposure adjustment unit 61 in a state where the subject is in normal brightness. Control of the aperture exposure control amount Ci, that is, an optical aperture The gain is adjusted by changing the amount, and is further adjusted by the gain exposure adjustment unit 62 by the gain correction amount Cg-s in a transient state described later. At this time, in the electronic shutter adjustment unit 63, the shutter exposure control amount Cs is a constant value.

  The high-speed shutter exposure control range ER-sH is a range in which exposure is adjusted by the electronic shutter adjustment unit 63 when the subject is in the brightest state, and is controlled by the shutter exposure control amount Cs, that is, charge accumulation of the electronic shutter adjustment unit 63. The time is adjusted by changing the time shorter than the time of one frame. At this time, the gain exposure adjustment unit 62 has a minimum value, and the aperture exposure adjustment unit 61 has a minimum aperture amount.

  FIG. 4 is an explanatory diagram for explaining the temporal change of the exposure value by the exposure adjustment unit, where the solid line indicates the temporal change of the aperture exposure control amount Ci of the aperture exposure adjustment unit 61, and the broken line indicates the gain of the gain exposure adjustment unit 62. The time change of the exposure control amount Cg is shown. Here, if the time until the predetermined exposure value EV0 is reached from the exposure evaluation value EV (pv) is defined by a time constant, the time constants of the aperture exposure adjustment unit 61 and the gain exposure adjustment unit 62 are expressed by Ti and Tg, respectively. Is done. At this time, since Tg <Ti, the gain exposure control amount Cg whose exposure is controlled by the gain exposure adjustment unit 62 is larger than the aperture exposure control amount Ci whose exposure is controlled by the aperture exposure adjustment unit 61. It turns out that it converges quickly. Further, the exposure value EV is controlled by a predetermined control amount for each frame unit, the aperture exposure control amount Ci of the aperture exposure adjustment unit 61 is small and controlled with high resolution, while the gain exposure control amount of the gain exposure adjustment unit 62 is controlled. Cg is a digital quantity and controlled with low resolution. Therefore, when the exposure value EV is controlled toward the exposure target value EV (sp), the final error ΔEVg due to the gain exposure control amount Cg of the gain exposure adjustment unit 62 is obtained. The final error ΔEVi due to the exposure control amount Ci is obtained, and it can be seen that ΔEVg> ΔEVi. That is, the aperture exposure adjustment unit 61 and the gain exposure adjustment unit 62 have different control characteristics depending on the response to the exposure target value EV (sp) and the resolution. Although the characteristics of the electronic shutter adjustment unit 63 are omitted here, the shutter exposure control amount Cs is set to a digital value and a different characteristic, like the gain exposure control amount Cg.

(2) Exposure control processing:
FIG. 5 is an explanatory diagram for explaining the exposure control process. In the exposure adjustment range ER, the aperture exposure adjustment unit 61, the gain exposure adjustment unit 62, and the electronic shutter adjustment unit 63 divide the respective areas in the exposure adjustment range ER, and the exposure evaluation value EV (pv) is the exposure target value EV (sp). In other words, a natural image is created by adjusting the exposure by the aperture exposure adjustment unit 61 that is an optical adjustment means within the aperture exposure control range ER-i that is normal brightness. Then, electrical exposure adjustment is performed by the gain exposure adjustment unit 62 and the electronic shutter adjustment unit 63 in the darker gain exposure control range ER-g and the low-speed shutter exposure control range ER-sL, and the aperture exposure control range ER Electrical exposure adjustment is performed by the electronic shutter adjustment unit 63 in the high-speed shutter exposure control range ER-sH brighter than -i.

  FIG. 6 is a flowchart for explaining the response area determination process executed by the microcomputer 40. As shown in FIG. 6, the response area determination process is executed in the aperture exposure control range ER-i and the gain exposure control range ER-g. That is, a deviation EV (err) from the exposure target value EV (sp) is calculated (step S101), and it is determined whether the deviation EV (err) is greater than or less than a predetermined threshold th (step S102). If the determination is affirmative, a transient state exposure value distribution process is executed (step S110). If the determination is negative, a steady state exposure value distribution process is executed (step S120).

  In the transient state exposure value distribution process shown in FIG. 7, the exposure control amount C is calculated (step S112), and then the exposure adjustment range ER is determined based on the exposure evaluation value EV (pv) (step S114). In subsequent step S116, the exposure correction means is selected. That is, if the exposure evaluation value EV (pv) is within the aperture exposure control range ER-i, the gain exposure adjustment unit 62 is selected as the exposure correction unit. In step S118, a gain correction amount Cg-s of the exposure correction unit is calculated. That is, as shown in FIG. 5, when the deviation EV (err) between the exposure evaluation value EV (pv1) and the exposure target value EV (sp1) is greater than or equal to a predetermined threshold th within the aperture exposure control range ER-i. In addition to the main control amount Ci-m of the aperture exposure control amount Ci, exposure control is performed by the gain exposure adjustment unit 62 with the gain correction amount Cg-s.

  In the steady state exposure value distribution process shown in FIG. 8, the exposure control amount C is calculated (step S122), and then the exposure adjustment range ER is determined based on the exposure evaluation value EV (pv) (step S124). In subsequent step S126, an exposure correction unit is selected. That is, if the exposure adjustment range ER is the gain exposure control range ER-g, the aperture exposure adjustment unit 61 is selected as the exposure correction unit. In step S128, the aperture correction amount Ci-s of the exposure correction unit is calculated. That is, as shown in FIG. 5, when the deviation EV (err) between the exposure evaluation value EV (pv2) and the exposure target value EV (sp2) is equal to or less than a predetermined threshold th within the gain exposure control range ER-g. In addition to the main control amount Cg-m of the gain exposure control amount Cg, the aperture exposure adjustment unit 61 performs exposure control with the aperture correction amount Ci-s.

  FIG. 9 is an explanatory diagram for explaining the exposure control processing in the aperture exposure control range ER-i, where the vertical axis indicates the exposure value and the horizontal axis indicates time. This control process shows a case where the exposure evaluation value EV (pv1) has converged to the exposure target value EV (sp1) from time t1. When it is determined that the deviation EV (err) between the exposure target value EV (sp1) and the exposure evaluation value EV (pv1) exceeds a predetermined threshold th, a transient state exposure value distribution process is executed, that is, aperture exposure control. In addition to the amount Ci, a gain correction amount Cg-s is also added to the exposure control amount C, and the corrected exposure control amount C has a value of (Ci + Cg). Therefore, in addition to the gentle value by the exposure control by the aperture exposure adjustment unit 61, the gain correction amount Cg-s having a large change by the gain exposure adjustment unit 62 is also added, and the exposure evaluation value EV (pv1) is quickly obtained. It approaches the exposure target value EV (sp1). When the deviation EV (err) is determined to be equal to or less than the predetermined threshold th at time t2, steady state exposure value distribution processing is executed, that is, only exposure control based on the aperture exposure control amount Ci is executed, and exposure is performed. It converges to the target value EV (sp1) with a small error value.

  FIG. 10 is an explanatory diagram for explaining the exposure control process in the gain exposure control range ER-g. This control process shows a case where the exposure evaluation value EV (pv2) has converged to the exposure target value EV (sp2) from time t1. That is, when the deviation EV (err) between the exposure target value EV (sp2) and the exposure evaluation value EV (pv2) exceeds the predetermined threshold th and is determined to be in a transient state, the gain exposure adjustment unit 62 with high responsiveness is set. The gain exposure control amount Cg is selected. When the deviation EV (err) is determined to be equal to or less than the threshold th (time t2), steady state exposure value distribution processing is executed. In the steady state exposure value distribution process, in addition to the gain exposure control amount Cg, the aperture correction amount Ci-s is also added to the exposure control amount C, and the corrected exposure control amount C becomes a value of (Ci + Cg). Therefore, in addition to highly responsive exposure control by the gain exposure adjustment unit 62, a high-resolution aperture correction amount Ci-s by the aperture exposure adjustment unit 61 is also added, so that the exposure evaluation value EV (pv2) is quickly obtained as an exposure target value. Converges to EV (sp2).

(3) Operation and effect of embodiment The following operation and effect are exhibited by the configuration of the above embodiment.
(3) -1 As shown in FIG. 9, in the aperture exposure control range ER-i, exposure control is executed with high resolution by the aperture exposure adjustment unit 61. However, in order to compensate for the slow response performance of the exposure adjustment speed Vs. In addition, exposure control by the gain exposure adjustment unit 62 having a high exposure adjustment speed is added, and quick exposure control to the exposure target value EV (sp) can be performed.

(3) -2 As shown in FIG. 10, in the gain exposure control range ER-g, a high exposure adjustment speed is executed by the gain exposure adjustment unit 62. However, in order to compensate for the low resolution characteristics, the resolution is high. Exposure control by the aperture exposure adjustment unit 61 is also added, and it is possible to converge to the exposure target value EV (sp) with high accuracy.

(3) -3 As shown in FIG. 5, by using the respective correction values of the aperture exposure adjustment unit 61 and the gain exposure adjustment unit 62 in a wide range of the exposure adjustment range ER, switching is performed quickly and with high accuracy. Exposure control can be performed.

(3) -4 The aperture exposure adjustment unit 61 and the gain exposure adjustment unit 62 of the present embodiment are general-purpose aperture exposure adjustment means, and it is not necessary to add a special mechanism to the conventional exposure adjustment unit, thereby improving response characteristics. And high exposure adjustment accuracy can be obtained.

(4) Other Embodiments The present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

(4) -1 In the above embodiment, the resolution and responsiveness of the aperture exposure adjustment unit 61 and the gain exposure adjustment unit 62 are compensated for the characteristics of the aperture exposure adjustment unit 61, the gain exposure adjustment unit 62, and the electronic shutter adjustment unit 63. Although it is configured, various methods can be set as long as the method compensates the characteristics of other exposure ranges in accordance with the characteristics of the exposure adjustment unit, and the exposure control range to be corrected may be over a plurality of ranges. Further, the same type of exposure adjusting unit may be applied to the configuration with different resolution and response characteristics. For example, the range of exposure control by the aperture exposure adjusting unit 61 is divided into a plurality of ranges. These resolutions and responsiveness may be changed.

(4) -2 In the above embodiment, a case has been described in which the correction amount for correcting the exposure adjustment range is constant. However, the correction amount is changed according to the magnitude of the deviation, or an intermediate value is set for the correction amount itself. You may set suitably.

(4) -3 In the above embodiment, the aperture exposure adjustment unit, the gain exposure adjustment unit, and the electronic shutter adjustment unit have been described as the exposure adjustment unit. However, the present invention is not limited to this, and a neutral density filter, a mechanical shutter, a liquid crystal shutter, etc. There is no particular limitation as long as the exposure can be adjusted.

DESCRIPTION OF SYMBOLS 10 ... Video camera 20 ... Lens unit 21 ... 1st lens 22 ... Zoom lens 22D ... Zoom driver 22M ... Zoom motor 22S ... First origin sensor 23 ... Iris mechanism 23D ... Iris driver 23M ... Iris motor 23S ... Iris position sensor 24 ... third lens 25 ... focus lens 25D ... focus driver 25M ... focus motor 25S ... second origin sensor 30 ... imaging device 34 ... image processing DSP
36 ... Output terminal 40 ... Microcomputer 51 ... Exposure value calculation unit 52 ... Exposure value distribution unit 61 ... Aperture exposure adjustment unit 62 ... Gain exposure adjustment unit 63 ... Electronic shutter adjustment unit Cg ... Gain exposure control amount Cg-s ... Gain correction Amount Ci ... Aperture exposure control amount Ci-m ... Main control amount Ci-s ... Aperture correction amount Cs ... Shutter exposure control amount ER ... Exposure adjustment range ER-g ... Gain exposure control range ER-i ... Aperture exposure control range ER- sH: High-speed shutter exposure control range ER-sL: Low-speed shutter exposure control range

Claims (3)

Using an imaging device that images a subject and outputs a video signal including a luminance signal, an exposure evaluation value calculated based on the luminance signal, and an exposure target value that is a target exposure for the exposure evaluation value, An exposure control apparatus comprising: a first exposure adjustment unit that performs exposure adjustment; and an exposure control unit that performs exposure control with a second exposure adjustment unit that performs exposure adjustment at a lower exposure resolution than the first exposure adjustment unit at a lower exposure adjustment speed. Because
The exposure control means includes
An exposure area setting unit that sets an exposure adjustment range in which exposure is adjusted according to the luminance signal divided into a first exposure control range and a second exposure control range;
An exposure control amount setting unit that sets an exposure control amount that can be adjusted by the first exposure adjustment unit to a main adjustment amount and a correction amount;
A deviation between the exposure target value and the exposure evaluation value is obtained, and when the deviation is equal to or less than a predetermined value and exposure control is performed in the second exposure control range, in addition to exposure control by the second exposure adjustment unit An exposure correction control unit in which the first exposure adjustment unit controls exposure with the correction amount;
An exposure control device comprising: The exposure control device according to claim 1,
The first and second exposure adjustment units are a diaphragm exposure adjustment unit that controls the amount of light to the image sensor, a gain exposure adjustment unit that amplifies the video signal of the image sensor, or an accumulation of charges accumulated in the image sensor. An exposure control device that is one of electronic shutter adjustment units that change time. A first exposure adjustment unit that performs exposure adjustment using an exposure evaluation value calculated based on a luminance signal from an image sensor that images a subject and an exposure target value that is a target exposure with respect to the exposure evaluation value; and In an exposure control method in which exposure control is performed by a second exposure adjustment unit that performs exposure adjustment at a lower exposure resolution than the first exposure adjustment unit and at a lower resolution,
An exposure adjustment range in which exposure adjustment is performed according to the luminance signal is set separately for a first exposure control range and a second exposure control range,
The exposure control amount that can be adjusted by the second exposure adjustment unit is set separately for the main adjustment amount and the correction amount,
A deviation between the exposure target value and the exposure evaluation value is obtained, and when the deviation is equal to or less than a predetermined value and exposure control is performed in the second exposure control range, in addition to exposure control by the second exposure adjustment unit The exposure control method, wherein the first exposure adjustment unit performs exposure control with the correction amount.

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