JP2021182693A - Imaging apparatus and method for controlling the same - Google Patents

Abstract

To make the amount of exposure of an image pick-up device uniform with a simple configuration in an imaging apparatus using an electronic front curtain and a mechanical rear curtain.SOLUTION: An imaging apparatus 100 has an image pick-up device 205 that performs an electronic shutter operation as a front curtain, and a mechanical shutter 206 that operates as a rear curtain. The imaging apparatus has vibration detection means 204 that detects the vibration of the imaging apparatus. Control means 201, 601-607 acquire information on the operating characteristics of the mechanical shutter by using information on the detected vibration, and controls the electronic shutter operation by using the information on the operating characteristics of the mechanical shutter.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image pickup apparatus that controls an exposure amount using an electronic front curtain and a mechanical rear curtain.

Some image pickup devices (digital cameras) use an electronic shutter of the image pickup element as a front curtain and a mechanical shutter as a rear curtain to control the exposure amount of the image pickup element. In this way, when the exposure amount is controlled using the electronic front curtain and the mechanical rear curtain, in order to make the exposure amount uniform in the entire area of the image sensor, the operating characteristics (running curve) due to the aged deterioration of the mechanical rear curtain. It is necessary to control the operation start timing of the electronic front curtain according to the change of.

Patent Document 1 discloses an image pickup device that detects a traveling curve of a mechanical rear curtain by a photointerruptor (PI) and feeds back the detection result to the start timing of the electronic front curtain.

Japanese Unexamined Patent Publication No. 2007-28128

However, when the PI is used as in the image pickup apparatus of Patent Document 1, a holding component for holding the PI, a light-shielding component for detecting by the PI, and the like are required, which leads to an increase in the size of the mechanical shutter.

The present invention provides an image pickup apparatus using an electronic front curtain and a mechanical rear curtain, which can make the exposure amount of the image pickup element uniform with a simple configuration.

The image pickup device as one aspect of the present invention has an image pickup element that operates as an electronic shutter as a front curtain and a mechanical shutter that operates as a rear curtain. The image pickup apparatus has a control means for controlling the operation of the electronic shutter and a vibration detection means for detecting the vibration of the image pickup apparatus. The control means is characterized in that it acquires information on the operating characteristics of the mechanical shutter using the information on the detected vibration and controls the electronic shutter operation using the information on the operating characteristics of the mechanical shutter.

Further, the control method as another aspect of the present invention is applied to an image pickup device having an image pickup element that performs an electronic shutter operation as a front curtain and a mechanical shutter that operates as a rear curtain. The control method includes a step of detecting the vibration of the image pickup apparatus, a step of acquiring information on the operating characteristics of the mechanical shutter using the information on the detected vibration, and an electronic shutter operation using the information on the operating characteristics of the mechanical shutter. It is characterized by having a step for controlling. A computer program that causes the computer of the image pickup apparatus to execute a process according to the above control method also constitutes another aspect of the present invention.

According to the present invention, information on the operating characteristics of the mechanical shutter as the rear curtain is acquired with a simple configuration, and the running characteristics of the electronic shutter operation as the front curtain are corrected by using the information, thereby exposing the image sensor. The amount can be uniform.

The external view of the digital camera which is an Example of this invention. The block diagram which shows the structure of the digital camera of an Example. A timing chart showing an imaging sequence in the examples. The figure explaining the occurrence of the exposure unevenness due to the aging deterioration of the mechanical rear curtain. A timing chart showing the drive of the mechanical shutter measured by vibration detection. The flowchart which shows the signal analysis processing in an Example. The flowchart which shows the determination process in an Example. The flowchart which shows the correction process in an Example. The figure explaining the correction of the traveling curve of the electronic front curtain in an Example.

Hereinafter, examples of the present invention will be described with reference to the drawings.

1A and 1B show an interchangeable lens digital camera (hereinafter, simply referred to as a camera) 100 as an image pickup apparatus according to an embodiment of the present invention, and FIG. 1A shows a front side (subject side). ), And FIG. 1B shows the camera 100 seen from the rear side.

An interchangeable lens 102 is detachably attached to a mount portion on the front surface of the camera body 101, which is the main body of the camera 100. A release switch 104 operated by a user to instruct imaging is provided on the upper surface of the camera body 101. When the release switch 104 is half-pressed, an imaging preparation operation such as AF or AE is performed, and when the release switch 104 is fully pressed, a still image imaging operation is performed.

Further, on the back surface of the camera body 101, a display unit 103 for displaying captured images and various information, a moving image switch 105 operated by the user to instruct the start and stop of moving image imaging, and a user for selecting an imaging mode. A mode selection lever 106 to be operated and a menu button 107 for setting the functions of the camera 100 are provided. Further, on the back surface of the camera body 101, an up / down switch 108, 109 and a dial 110 operated by the user to change various setting values, and an image recorded on a recording medium mounted on the camera 100 are displayed on the display unit 103. A reproduction button 111 is provided for the user to select a reproduction mode to be reproduced above.

FIG. 2 shows the internal configuration of the camera 100 and the interchangeable lens 102. An imaging optical system 207 is provided in the interchangeable lens 102. The image pickup optical system 207 forms an image of light from a subject (not shown). The imaging optical system 207 can perform zooming and focusing by moving the lens along the optical axis 208.

The subject image formed by the image pickup optical system 207 is imaged (photoelectrically converted) by an image pickup element 205 such as a CMOS sensor provided in the camera body 101. Image data is generated by performing various image processing on the image pickup signal output from the image pickup element 205 by an image processing unit (not shown). The image data is recorded on a recording medium such as a semiconductor memory. In still image imaging, the image sensor 205 can perform a reset operation that resets the charge of the pixel for each line according to the operation characteristics recorded in advance in response to a command from the camera CPU 201. In this embodiment, this reset operation, that is, the electronic shutter operation is used as a front curtain (hereinafter referred to as an electronic front curtain).

A mechanical shutter 206 is arranged in front of the image sensor 205 in the camera body 101. The mechanical shutter 206 controls the amount of light (exposure amount) incident on the image pickup device 205 from the image pickup optical system 207 by traveling a plurality of light-shielding blades from a superposed state to a deployed state. In this embodiment, this mechanical shutter 206 is used as a rear curtain (hereinafter referred to as a mechanical rear curtain).

The camera CPU 201 provided in the camera body 101 controls various operations of the camera 100 and the interchangeable lens 102 according to the operation of the release button 104 and the like.

The vibration detecting unit (vibration detecting means) 204 provided in the camera body 101 is configured by using an angular velocity sensor or an acceleration sensor, and detects the angular velocity and acceleration of the vibration of the camera body 101. The angular velocity and acceleration detected by the vibration detection unit 204 are used for image shake correction and determination of the posture of the camera 100. The calculation unit 209 integrates signals indicating acceleration and angular velocity detected by the vibration detection unit 204 and converts them into vibration detection signals (information about vibration) indicating displacement and angle. The runout correction control unit 210 controls the drive unit of the runout correction mechanism 202 by using the vibration detection signal obtained by the calculation unit 209. The drive unit of the image stabilization mechanism 202 drives the image pickup device 205 in the direction orthogonal to the optical axis 208 as shown by the arrow 202 (a) in response to the control by the image stabilization control unit 210. As a result, the image shake caused by the shake of the camera 100 is corrected. The runout correction mechanism 202 and the runout correction control unit 210 configure the runout correction means.

Here, the image pickup sequence of the still image in the camera 100 will be described with reference to FIG. In FIG. 3, the RLS is a signal output when the release button 104 is fully pressed. When the user fully presses the release switch 104 at time t1, the RLS signal changes and the camera 100 starts the imaging operation from the imaging standby state.

In the imaging operation, when the front curtain start signal SIG_A is output from the camera CPU 201 at time t2, the electronic front curtain responds to the preset operating characteristics (hereinafter referred to as traveling characteristics), which is a curve A. According to the above, the reset operation (running) is controlled until the time t3. As a result, each line of the pixels of the image sensor 205 is exposed. t_ESH indicates the front curtain running time (operating time) from the running start time t2 at which the electronic front curtain starts running to the running completion time t3 at which the running is completed.

After the running of the electronic front curtain is started, the camera CPU 201 outputs the rear curtain start signal SIG_B at time t4, and the holding by the electromagnet provided in the mechanical shutter 206 is released accordingly. As a result, the mechanical rear curtain urged by the traveling spring (not shown) starts operating (traveling) and shields the light toward the image pickup element 205. The curve B in FIG. 3 is a running curve of the mechanical rear curtain. The running of the mechanical trailing curtain is completed in time t5. t_MSH indicates the rear curtain traveling time (operating time) from the traveling start time t4 at which the mechanical rear curtain starts traveling to the traveling completion time t5 at which the traveling is completed.

Ex_A, Ex_B, and Ex_C in FIG. 3 indicate the exposure time of the image pickup device 205 at the initial exposure stage, the middle exposure stage, and the final exposure stage, which is determined by the curve A and the curve B. When the curve A and the curve B coincide with each other, Ex_A, Ex_B, and Ex_C become equal to each other, and the entire surface of the image pickup device 205 can be exposed with a uniform exposure amount. In this case, t_ESH and t_MSH are equal to each other as shown in the equation (1).
t_ESH = t_MSH (1)
However, in the mechanical rear curtain, the traveling characteristics, which are the operating characteristics, change due to aged deterioration such as wear of the sliding portion of the mechanical shutter 206 and a decrease in the urging force of the traveling spring. FIG. 4 shows the occurrence of exposure unevenness due to aged deterioration of the mechanical rear curtain. In FIG. 4, the same reference numerals as those in FIG. 3 have the same meanings as those in FIG.

In FIG. 4, the curve B2 showing the running characteristics of the mechanical rear curtain that has deteriorated over time is a gentle curve with respect to the curve B shown in FIG. That is, as shown by the equation (2), the rear curtain traveling time t_MSH_2 on the curve B2 is longer than the rear curtain traveling time t_MSH on the curve B by the amount of change Δt_MSH.
t_MSH_2-t_MSH = Δt_MSH (2)
Curve B2 does not match curve A. As a result, the exposure times Ex_A2, Ex_B2, and Ex_C2 at the initial exposure, the middle exposure, and the final exposure of the image sensor 205 are different from each other, and the exposure amount of the image sensor 205 becomes uneven. If a still image is taken in such a state, a low-quality still image may be generated.

The vibration detection unit 204 shown in FIG. 2 also detects vibration generated by driving the mechanical rear curtain. FIG. 5 shows a waveform of a vibration detection signal (hereinafter referred to as a shutter drive waveform) indicating vibration caused by driving the mechanical rear curtain detected by the vibration detection unit 204 in the imaging sequence shown in FIGS. 3 and 4. In FIG. 5, the same reference numerals as those in FIGS. 3 and 4 have the same meanings as those in the drawings.

In FIG. 5, SHOCK_1 shows a shutter drive waveform in a combination of an electronic front curtain and a mechanical rear curtain that has not deteriorated over time as shown in FIG. When the RLS signal is output at time t1, the traveling spring is charged before the mechanical rear curtain is traveled. The waveform appearing from time t1 to time t2 in SHOCK_1 indicates vibration due to this charging operation.

After that, when the front curtain running start signal SIG_A is output at time t3 and the electronic front curtain running is started, the rear curtain running start signal SIG_B is output at a delay time t4 by the target exposure time, and after mechanically. The curtain starts running. The large amplitude waveform appearing in SHOCK_1 at the subsequent time t5 indicates the vibration generated when the mechanical rear curtain that has completed running hits the mechanical end. That is, it indicates that the running of the mechanical rear curtain was completed at time t5.

In this way, the vibration detection unit 204 can be used to accurately detect the vibration generated by driving the mechanical rear curtain in real time.

On the other hand, SHOCK_2 in FIG. 5 shows a shutter drive waveform in a combination of an electronic front curtain and a mechanically deteriorated mechanical rear curtain as shown in FIG. The waveform in SHOCK_1 immediately before time t1 to time t5 is the same as that of SHOCK_1. However, in SHOCK_2, a waveform indicating the completion of running of the mechanical rear curtain appears at a time t6 later than the time t5. That is, it can be detected that the trailing curtain running time t_MSH_2 is longer by Δt_MSH than t_MSH when the mechanical trailing curtain has not deteriorated over time.

In this embodiment, the change amount of the rear curtain running time is acquired by using the shutter drive waveform detected by the vibration detection unit 204 provided in the camera 100 for image shake correction, and the change amount is used. It suppresses the occurrence of uneven exposure due to aging deterioration of the mechanical trailing curtain.

In FIG. 2, the signal detection unit 601 acquires the signal output from the camera CPU 201. When the analysis unit A602 determines that the signal acquired by the signal detection unit 601 is the rear curtain travel start signal SIG_B, the analysis unit A602 sets the time point (or after a predetermined delay time) as the travel start timing of the mechanical rear curtain. The analysis unit B603 detects the travel completion timing of the mechanical rear curtain from the vibration detection signal (shutter drive waveform) output from the vibration detection unit 204.

The SH recording unit 605 records the rear curtain running time t_MSH (first operating time) with respect to the mechanical rear curtain before aging deterioration acquired in the manufacturing process of the camera 100. The SH calculation unit 604 sets the rear curtain travel time (second operating time) t_MSH_2 from the travel start timing of the mechanical rear curtain set by the analysis unit A602 to the travel completion timing of the mechanical rear curtain detected by the analysis unit B603. calculate.

The SH determination unit 606 calculates the amount of change Δt_MSH, which is the difference between the rear curtain travel time t_MSH_2 calculated by the SH calculation unit 604 and the rear curtain travel time t_MSH before aging deterioration recorded in the SH recording unit 605. The SH correction unit 607 corrects the curve A of the electronic front curtain by using the curve correction data (which will be described later) according to the change amount Δt_MSH calculated by the SH determination unit 606. The curve correction data may be recorded in the form of table data for each change amount Δt_MSH, or may be calculated using an arithmetic expression with the change amount Δt_MSH as a variable.

The camera CPU 201, the signal detection unit 601 and the analysis unit A602, the analysis unit B603, the SH calculation unit 604, the SH determination unit 606, and the SH correction unit 607 are composed of a single or a plurality of microcomputers (control means) and are computer programs. Each process is performed according to the above.

The flowchart of FIG. 6A shows the processing performed by the analysis unit A602, and the flowchart of FIG. 6B shows the processing performed by the analysis unit B603. Further, FIG. 6C shows an imaging sequence and a shutter vibration waveform when the processing of each step of both flowcharts is performed. In FIG. 6 (c), the same reference numerals as those in FIG. 5 have the same meanings as those in FIG.

In FIG. 6A, the analysis unit A602, which started the process in step 701, determines SIG_B acquired by the signal detection unit 601 in step 702. Next, in step 703, the analysis unit A602 determines the time t74 when the value of SIG_B changes to TTL_a or less shown in FIG. 6 (c). Then, in the next step 704, the analysis unit A602 sets the time t74 as the travel start time of the mechanical rear curtain and sends it to the SH calculation unit 604.

In FIG. 6B, the analysis unit B603, which started the process in step 706, acquires a vibration detection signal (shutter drive waveform SHOCK in FIG. 6C) from the vibration detection unit 204 in step 707. Next, in step 708, the analysis unit B603 determines the time t75 at which the SHOCK value (amplitude) changes to + SH_a or more or −SH_a or less as shown in FIG. 6 (c). Then, in step 709, the time t75 is sent to the SH calculation unit 604 as the travel completion time of the mechanical rear curtain.

The SH calculation unit 604 calculates the trailing curtain travel time t_MSH_2, which is the difference between the travel start time t74 from the analysis unit A602 and the travel completion time t75 from the analysis unit B603, and sends this to the SH determination unit 606.

The flowchart of FIG. 7 shows a process performed by the SH determination unit 606. The SH determination unit 606, which has received the rear curtain travel time t_MSH_2 from the SH calculation unit 604 in step 801, acquires the rear curtain travel time t_MSH before aging deterioration from the SH recording unit 605 in step 802.

Next, in step 803, the SH determination unit 606 calculates a change amount Δt_MSH which is a difference between the rear curtain travel time t_MSH_2 received from the SH calculation unit 604 and the rear curtain travel time t_MSH acquired from the SH recording unit 605. It is sent to the SH correction unit 607.

The flowchart of FIG. 8 shows the processing performed by the SH correction unit 607. The SH correction unit 607, which has acquired the change amount Δt_MSH from the SH determination unit 606 in step 901, acquires the curve correction data that matches or is closest to the change amount Δt_MSH from the curve correction data data table described later in step 902. Then, in step 903, the SH correction unit 607 corrects the traveling characteristic (curve A) of the electronic front curtain so as to match the curve correction data acquired in step 902.

9 (a) to 9 (c) will be used to describe the correction of the curve A, which is the traveling curve of the electronic front curtain, by the SH correction unit 607. FIG. 9A shows a curve for each operation number (1 time, 100 times, 200 times) of the mechanical shutter (mechanical rear curtain) 202 acquired in the manufacturing process (test process) of the camera 100. FIG. 9B shows the change amount Δt_MSH (Δt_1, Δt_2, ...) Of the rear curtain running time depending on the number of operations of the mechanical rear curtain, and the curve correction data as a polynomial that approximates the running curve for each change amount. There is. FIG. 9C shows curves A and A2 of the electronic front curtain before and after correction, before aging deterioration (number of operations = first number of times: 1 time) and after aging deterioration (number of operations = second number of times). : For example, 100 times) The curves B and B2 of the mechanical rear curtain are shown. The curve B of the mechanical rear curtain before aging deterioration coincides with the curve A of the electronic front curtain before correction.

On the other hand, the curve B2 of the mechanical rear curtain after aging does not match the curve A of the electronic front curtain before correction. As described above, the rear curtain travel time is acquired using the vibration detection signal, and the amount of change Δt_MSH, which is the difference between the rear curtain travel times t_MSH and t_MSH_2 before and after aging deterioration, is calculated. The SH correction unit 607 acquires curve correction data corresponding to the calculated change amount Δt_MSH (that is, for a change amount that matches or is closest to the calculated change amount) from the curve correction data data table, and the electronic front curtain. The curve A of is corrected to the curve A2 represented by the polynomial represented by the acquired curve correction data. This makes it possible to obtain a curve A2 that matches or approximates the curve B2.

Then, by traveling the electronic front curtain according to the curve A2, the entire surface of the image pickup element 205 can be uniformly exposed in combination with the mechanical rear curtain traveling on the curve B2, and imaging with less exposure unevenness becomes possible. ..

As described above, according to this embodiment, the running characteristics of the mechanical rear curtain are detected by using the vibration detection unit 204 used for image shake correction without using the PI for detecting the running characteristics of the mechanical rear curtain. Then, the operation of the electronic shutter operation is controlled so that the traveling characteristic of the electronic shutter operation matches or approaches the traveling characteristic of the detected rear curtain (corrects the traveling characteristic of the electronic shutter operation). As a result, the exposure amount of the image pickup device can be made uniform with a simple configuration.

It is desirable that the vibration detection unit 204 is arranged at a position as close as possible to the mechanical shutter 206, which is the vibration generation source. This is because the vibration from the mechanical shutter 206 can be detected without delay when the mechanical shutter 206 and the vibration detection unit 204 are physically close to each other.

Further, in the present embodiment, the case where the image stabilization mechanism 202 is provided in the camera 100 has been described, but the image stabilization mechanism for driving the lens in the direction orthogonal to the optical axis or the like in the interchangeable lens 102 is provided. The image stabilization mechanism may be provided and controlled based on the vibration detected by the vibration detection unit 204 in the camera 100.
(Other examples)
The present invention supplies a program that realizes one or more functions of the above-described embodiment to a system or device via a network or storage medium, and one or more processors in the computer of the system or device reads and executes the program. It can also be realized by the processing to be performed. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Each of the above-described embodiments is only a representative example, and various modifications and changes can be made to each embodiment when the present invention is implemented.

100 Camera 202 Image stabilization mechanism 204 Vibration detection unit 205 Image sensor 206 Mechanical shutter 601 Signal detection unit 602 Analysis unit A
603 Analysis Department B
604 SH calculation unit 606 SH judgment unit 607 SH correction unit

Claims (9)

An image pickup device having an image pickup element that operates as an electronic shutter as a front curtain and a mechanical shutter that operates as a rear curtain.
A control means for controlling the electronic shutter operation and
It has a vibration detecting means for detecting the vibration of the image pickup apparatus, and has a vibration detecting means.
The control means is
Information on the operating characteristics of the mechanical shutter is acquired using the detected information on the vibration.
An image pickup apparatus characterized in that the electronic shutter operation is controlled by using information on the operation characteristics of the mechanical shutter. The image pickup apparatus according to claim 1, wherein the control means controls the electronic shutter operation so that the operating characteristics of the electronic shutter operation match or approach the operating characteristics of the mechanical shutter. The control means is
The electronic shutter operation is controlled according to the set operating characteristics, and the electronic shutter operation is controlled.
The image pickup apparatus according to claim 1 or 2, wherein the operating characteristics of the electronic shutter operation are corrected by using the information regarding the operating characteristics of the mechanical shutter. The information regarding the operating characteristics of the mechanical shutter includes the first operating time from the start to the completion of the operation of the mechanical shutter when the number of operations of the mechanical shutter is the first number, and the number of operations of the mechanical shutter. Any one of claims 1 to 3, which is a difference from the second operation time from the start to the completion of the operation of the mechanical shutter when the second number of times is larger than the first number of times. The image pickup apparatus according to the above. The control means is
The correction data indicating the operating characteristics of the mechanical shutter corresponding to the difference is acquired, and the correction data is acquired.
The image pickup apparatus according to claim 4, wherein the correction data is used to correct the operation characteristics of the electronic shutter operation. The imaging device according to claim 5, wherein the correction data is polynomial data that approximates the operating characteristics of the mechanical shutter. The invention according to any one of claims 1 to 6, further comprising a vibration correcting means for driving the image pickup element so as to correct image vibration with respect to the vibration detected by the vibration detecting means. Image sensor. It is a control method of an image pickup device having an image pickup element that performs an electronic shutter operation as a front curtain and a mechanical shutter that operates as a rear curtain.
The step of detecting the vibration of the image pickup device and
A step of acquiring information on the operating characteristics of the mechanical shutter using the detected information on the vibration, and
A control method for an image pickup apparatus, comprising: a step of controlling the electronic shutter operation using information on the operation characteristics of the mechanical shutter. A computer program characterized in that a computer of an image pickup apparatus having an image pickup element that performs an electronic shutter operation as a front curtain and a mechanical shutter that operates as a rear curtain is made to execute a process according to the control method according to claim 7.

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