JPH11234574A - Method for adjusting mechanical shutter for electronic camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust dispersion in mechanical delay of a mechanical shutter that differs from each camera with high accuracy in an electronic camera that uses both the mechanical shutter and an electronic shutter in order to conduct exposure control. SOLUTION: A deviation from a specified exposure control time due to mechanical delays dispersion of cameras, occurring untill a mechanical shutter 16 is actually closed after application of a mechanical shutter drive pulse instructing a closing operation of the mechanical shutter 16, is adjusted by shifting the application timing of the mechanical shutter drive pulse forward or backward or adjusting a charge storage start timing of an electronic shutter forward or backward. In this case, after the mechanical shutter 16 is assembled with the camera, the adjustment is conducted while evaluating the exposure by using a signal integrated value from an exposure calculation integration circuit 44.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting a mechanical shutter of an electronic camera, and more particularly to an electronic camera for controlling an exposure time by using both a mechanical shutter and an electronic shutter. To a method for correcting

[0002]

2. Description of the Related Art As an electronic camera using both a so-called electronic shutter function for controlling a charge accumulation time of an image pickup device and a mechanical shutter (mechanical shutter), for example,
There is one disclosed in JP-A-9-83875. This type of electronic camera uses only the electronic shutter function when monitoring a preview moving image on a liquid crystal monitor or the like provided in the main body before shooting or when performing exposure calculation (AE) immediately before shooting. The mechanical shutter and the electronic shutter are used together only when shooting (during actual imaging).

[0003]

However, such a conventional electronic camera has the following problems. That is, the mechanical shutter has a mechanical delay from when an electric mechanical shutter drive pulse for instructing the shutter operation is applied to when the shutter actually operates. This delay has a different value one by one, which is a variation as a shutter. This variation will be referred to as a machine difference in this specification.

[0004] Although it is possible to suppress this machine difference within a certain range with high precision, the shutter becomes extremely expensive as a result. Further, even if the above-described machine difference is adjusted by the mechanical shutter alone, there is a problem that after the shutter is actually incorporated into the camera, the unevenness is different due to mechanical stress accompanying assembly. .

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and provides a method for adjusting the mechanical shutter of an electronic camera which can adjust the variation (machine difference) of the mechanical shutter with high accuracy using simple means. The purpose is to provide.

[0006]

According to a first aspect of the present invention, there is provided an electronic shutter for controlling a charge accumulation time of an image pickup device, and a mechanism capable of shielding / opening an optical path incident on the image pickup device. In an electronic camera having both a shutter and a mechanical shutter drive pulse for instructing the closing operation of the mechanical shutter, a mechanical delay until the mechanical shutter actually closes from the specified exposure control time caused by variations among individuals. The displacement is corrected by adjusting the application timing of the mechanical shutter drive pulse.

That is, the exposure time is defined by the start of charge storage by the electronic shutter and the closing operation of the mechanical shutter. In the present invention, the mechanical delay of the mechanical shutters which differ from one another is considered. The timing of applying the mechanical shutter drive pulse is adjusted on the shutter drive control system side. In this way, the shift is substantially corrected by shifting the application timing of the mechanical shutter drive pulse back and forth by the time corresponding to the shift of the actual control time with respect to the specified exposure time. This makes it possible to easily and accurately adjust the mechanical shutter without using a special adjustment jig or the like.

According to a second aspect of the present invention, there is provided an electronic camera wherein the start of exposure at the time of imaging is defined by the start of charge accumulation by an electronic shutter and the end of exposure is defined by a closing operation of the mechanical shutter. Instead of adjusting the drive pulse application timing, adjustment of the charge accumulation start timing by the electronic shutter is performed. As in the present invention, the mechanical closing position of the mechanical shutter is fixed without adjustment, and the control side of the electronic shutter adjusts the exposure start timing (charge accumulation start timing) back and forth to obtain the prescribed exposure. It is possible to correct the variation of the actual control time with respect to time. This makes it possible to easily and accurately adjust the mechanical shutter without using a special adjustment jig or the like.

Of course, both the adjustment of the application timing of the mechanical shutter drive pulse and the adjustment of the start timing of the charge accumulation time as described in claim 2 may be performed. If the mechanical shutter is adjusted as described above with the mechanical shutter alone, it is expected that another factor of variation will be added due to mechanical stress etc. after the mechanical shutter is actually installed in the camera. Is done. Therefore, it is desirable that the mechanical shutter be adjusted after the mechanical shutter is incorporated in the camera. In this regard, in the mechanical shutter adjustment method of the present invention, since the mechanical difference between the mechanical shutters is adjusted by the timing of the shutter drive control, the mechanical difference can be easily adjusted even after being incorporated in the camera.

As a specific procedure of the shutter adjusting method of the present invention, as described in claim 4, the light amount is grasped in advance by controlling the exposure time using only the electronic shutter so as to obtain a predetermined accumulation time. First, the first integrated data obtained by integrating the output signal read from the image sensor at this time is acquired, and then (or prior to) this, the electronic shutter and the mechanical shutter are used in combination to perform the exposure. The light source is imaged by controlling the time, and at this time, second integrated data obtained by integrating output signals read from the image sensor is obtained. Based on a comparison between the first and second integrated data, a mechanical There is a mode in which the application timing of the shutter drive pulse is adjusted or the charge accumulation start timing by the electronic shutter is adjusted.

In this case, for at least two types of accumulation times corresponding to a plurality of shutter times, the application timing of the mechanical shutter drive pulse is adjusted or the charge accumulation start timing by the electronic shutter is adjusted. By performing the adjustment, more accurate adjustment can be performed. In the case of an electronic camera having a variable aperture,
Since the center of the mechanical shutter may not coincide with the aperture, if the electronic camera has a variable aperture as described in claim 6, at least two types of apertures are changed by changing the F value of the aperture. It is desirable to adjust the application timing of the mechanical shutter drive pulse or the charge accumulation start timing by the electronic shutter for each aperture. This enables more accurate adjustment.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method for adjusting a mechanical shutter of an electronic camera according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing a configuration of an electronic camera to which the present invention is applied. The electronic camera 10 mainly includes a photographing lens 12, an aperture 14, a mechanical shutter 16, a solid-state imaging device 18, an analog signal processing circuit 20, an A / D converter 22, a main signal processing unit 24, a memory 26, and a D / A converter. 28, LCD monitor 30, compression /
It comprises a decompression circuit 32, a memory card 34, a control circuit 36, a central processing unit (CPU) 38 and the like.

Although the photographing lens 12 is shown in a simplified manner in the drawing, the photographing lens 12 is composed of one or a plurality of lenses, and may be a lens having a single focal length (fixed focus), a zoom lens or a step zoom. A variable focal length lens such as a lens may be used. The photographing lens 12 includes a control circuit 36
Is controlled via the. The aperture 14 has, for example, a plurality of aperture holes having different diameters formed in one aperture plate, and the aperture can be switched by an electric driving means (not shown). In the figure, the diaphragm 14 is a diaphragm plate having two types of diaphragm holes. However, the diaphragm 14 is fixed, or the diaphragm is a continuous diaphragm that can be continuously changed. A form in which the diaphragm and the diaphragm are shared is also possible.

The mechanical shutter 16 includes a solid-state image sensor 18
The incident light path of the solid-state imaging device 18 is shielded / opened by a not-shown electric drive unit controlled by a control circuit 36. As the solid-state imaging device 18, a known two-dimensional imaging device (plane imaging device) is used. The imaging device is a CCD
There are various forms such as a type, a MOS type, and a CID type, and any type of imaging device may be adopted. In the present embodiment, photoelectric conversion elements (photosensors) are two-dimensionally arranged. An interline CCD image pickup device in which signal charges accumulated in each sensor are output via a vertical transfer path and a horizontal transfer path is employed.

The solid-state image pickup device 18 is provided with a sweep drain for discharging unnecessary charges, and drives a read gate by a shutter gate pulse to sweep signal charges accumulated in each sensor. ) Can be swept away. That is, this imaging device
It has a so-called electronic shutter function of controlling the accumulation time (shutter speed) of the electric charge accumulated in each sensor by the shutter gate pulse.

The light that has passed through the taking lens 12 is
4 and the mechanical shutter 16, the solid-state imaging device 1
8 is projected onto the image. At this time, the charge accumulation time of the solid-state imaging device 18 is controlled by the electronic shutter function via the control circuit 36. The subject image formed on the light receiving surface of the solid-state imaging device 18 is converted into a signal charge of an amount corresponding to the amount of incident light by each sensor and sequentially read out as an imaging output signal. Supplied to

The analog signal processing circuit 20 includes a CDS clamp circuit, a gain adjustment circuit, and the like.
The image pickup output signal (analog electric signal) input from the controller is appropriately processed based on the control of the control circuit. The signal output from the analog signal processing circuit 20 is converted into a digital signal by the A / D converter 22 and then applied to the main signal processing unit 24.

The main signal processing section 24 includes a gain adjusting section 4
0, an offset circuit 42, an AE integration circuit 44, a histogram generation unit 46, a digital signal processing circuit 48, and the like. The data output from the A / D converter 22 is applied to an AE integration circuit 44, a histogram generation unit 46, and a digital signal processing circuit 48 via a gain adjustment unit 40 and an offset circuit 42.

The AE accumulator circuit 44 includes the A / D converter 22
Are integrated with each other for one screen (R, G, B digital signals). The integrated value thus obtained corresponds to data indicating the brightness of one screen, and exposure control such as control of an electronic shutter is performed based on the integrated value. The histogram generator 46 creates a histogram indicating the distribution of the integrated value of the image sensor signal with respect to the signal level from the data for one screen obtained from the A / D converter 22. Then, a gain value and an offset value are determined based on the histogram calculation, and the gain and the offset are controlled by the CPU 38 via the control circuit 36.

As described above, the signal having passed through the control of the gain and the offset is applied to the digital signal processing circuit 48. The digital signal processing circuit 48 has a luminance (Y)
The signal processing circuit includes a signal generation circuit and a color difference (C) signal generation circuit, and performs Y / C signal processing on a signal input from the offset circuit 42. Then, the image data subjected to the Y / C signal processing by the digital signal processing circuit 48 is temporarily stored in the memory 26.

The image data stored in the memory 26 is decoded, converted into an analog signal by a D / A converter 28, and supplied to a liquid crystal monitor 30 as image display means. Thus, the liquid crystal monitor 30 displays the solid-state image sensor 18
Is displayed. The LCD monitor 30 has
In addition to displaying a still image photographed based on a photographing start signal generated by pressing a shutter button (not shown) or the like, a video (through moving image or intermittent image) before the photographing start signal is input is also displayed. The signal converted into an analog signal by the D / A converter 28 can be extracted as an external video output from a video output terminal or the like.

Further, the image data of the main imaging obtained in response to the input of the photographing start signal is guided from the memory 26 to the compression / decompression circuit 32, where it is given a predetermined format (for example,
After being compressed in accordance with JPEG), it is recorded on a memory card 34 as a recording medium. The recording medium may take various forms such as a smart media and an IC card.

The image data stored in the memory card 34 can be called up through the CPU 38. The called up image data is subjected to decompression / reproduction processing by the compression / decompression circuit 32, and then stored in the memory 26 and the D / A converter 28. The signal is output to the liquid crystal monitor 30 via a video signal output terminal (not shown) or the like, and can be output to another external device. CP
U38 is a control circuit 36, an AE integration circuit 4
4, histogram generation unit 46, digital signal processing circuit 4
8, connected to the memory 26, the memory card 34, etc., performs various calculations such as an exposure value and a focus position according to a predetermined algorithm, and comprehensively controls automatic exposure control, auto focus, auto strobe, auto white balance, and the like. Management. The CPU 38 controls a corresponding circuit based on various input signals input from an operation unit (not shown) such as a release button and a mode setting unit.

The autofocus means can take various forms. For example, a focus evaluation value indicating the sharpness of a subject image is calculated from an image signal, and the focus position is calculated based on the focus evaluation value. . Then, the photographing lens 12 is controlled via a focus drive circuit (not shown) according to the calculated focus position, and the focus position is set. In addition, a known distance measuring unit such as an AF sensor may be used.

On the other hand, the AE integrated value obtained by the AE integrating circuit 44 is notified to the CPU 38, and the CPU 38 calculates an exposure control value indicating an exposure time. Then, the obtained exposure control value is notified from the CPU 38 to the control circuit 36, and controls such as automatic exposure control, auto strobe, and auto white balance are performed through the control circuit 36.

The control circuit 36 controls the drive circuit of the solid-state imaging device 18 based on the exposure control value notified from the CPU 38, and sets the charge accumulation time of the solid-state imaging device 18, that is, the electronic shutter value, and sets the aperture. 14 and the opening / closing timing of the mechanical shutter 16 are controlled. As described above, all the exposure controls of the electronic camera 10 are automatically performed.

In the electronic camera configured as described above, during AE or preview, the mechanical shutter 16 is kept open, and only the electronic shutter is used to reduce the charge accumulation time (that is, the exposure time) of the solid-state imaging device 18. Control is performed, and at the time of actual photographing (at the time of capturing a recorded image), photographing is performed using both the mechanical shutter 16 and the electronic shutter.

FIG. 2 shows a timing chart of a photographing sequence at the time of actual photographing. In the figure, VD is a vertical drive pulse, and HD is a horizontal drive pulse. The cycle of the vertical drive pulse corresponds to a read cycle Tv for reading a signal from the solid-state imaging device 18. On the other hand, the cycle of the horizontal drive pulse corresponds to the horizontal scanning period (1H). As shown in the figure, the mechanical shutter 16 is in the open state before the start of the main imaging, and the accumulation of electric charge is started from the time t1 after the input of the vertical drive pulse. After charge accumulation starts at time t1,
At time t2, the shutter drive pulse goes high (H),
Shutter drive is instructed. Then, after a certain mechanical delay, the mechanical shutter 16 is actually closed to shield the solid-state imaging device 18 from light.

Therefore, the actual exposure time is the time from the start of charge storage by the electronic shutter (time t1) to the time when the mechanical shutter closes (t3). The charge accumulation signal obtained by such exposure is read out during a readout period synchronized with the next vertical drive pulse. Then, at an appropriate time after the reading, the mechanical shutter 16 is returned to the open state.

In the main imaging using both the mechanical shutter 16 and the electronic shutter, the exposure ends when the mechanical shutter 16 is used.
Light is not incident on the solid-state imaging device 18 after the exposure. Therefore, smear does not occur in principle in the main imaging. On the other hand, as shown in FIG. 3, the mechanical shutter 16 remains open during the display of the preview moving image (at the time of monitoring) or at the time of photometry (at the time of AE) performed prior to the main imaging, and the exposure period Is defined only by the electronic shutter. Therefore, light continues to enter the solid-state imaging device 18 even after the end of the charge accumulation time (Te) by the electronic shutter (after the exposure). That is, as shown in FIG. 4, the readout period (T
During v), light continues to hit the solid-state imaging device 18, which leaks into the vertical transfer path (vertical transfer CCD) of the solid-state imaging device 18, causing smear.

As described with reference to FIG. 2, the mechanical shutter 16 receives the electric mechanical shutter drive pulse and
There is a mechanical delay until the mechanical shutter 16 actually starts moving. This delay is a unique value for each mechanical shutter, and there is a difference between individuals. Conventionally, this variation (machine difference) is adjusted in a manufacturing process of the mechanical shutter so as to fall within a predetermined range. However, there is a problem that the cost increases.

Therefore, in the present embodiment, assuming that there is a mechanical difference between mechanical shutters, after assembling the mechanical shutter into a camera, adjustment is made for the entire camera to reduce the cost. Here, a procedure of a method of adjusting the mechanical shutter 16 in the electronic camera 10 will be described.

First, the mechanical shutter 10 is attached to the camera, and as shown in FIG. 5, the mechanical shutter drive pulse is set so as to have the longest shutter time within a range not exceeding the vertical drive cycle (1 V) of the solid-state image sensor 18. Set the position (application timing). The position of the mechanical shutter drive pulse is adjusted based on the vertical drive pulse (VD) by a delay time from the vertical drive pulse (VD). In practice, it is difficult to adjust the shutter time to a point just inside the vertical driving cycle, so that the adjustment is performed with a certain margin.

Since the closing operation of the mechanical shutter 16 actually takes a certain time, an intermediate point between the start time and the end time of closing the shutter is defined as "shutter closing time", and the shutter is closed. (The actual closing operation) is called “optical closing” to distinguish between the two. In general, it is difficult to detect the operation of the mechanical shutter 16 after the mechanical shutter 16 is built in the camera. In this regard, in this example, the operation of the mechanical shutter 16 is detected as follows.

That is, obviously, the control circuit 36 sends a shutter drive pulse so that the optical closing time of the mechanical shutter 16 is later than the readout start timing of the image sensor, and the output of the AE integration circuit 44 is output. obtain. Thereafter, the output of the AE integration circuit 44 is obtained while gradually shifting (shifting) the output timing of the shutter drive pulse forward in time.

FIG. 6 shows a state in which the output of the AE integration circuit 44 is monitored while shifting the timing of the shutter drive pulse. As shown in the figure, the relationship between the movement amount of the timing of the shutter drive pulse and the output (integrated value) of the AE integration circuit 44 is examined. Until the read timing is reached, the AE integration circuit 44
Output shows a substantially constant value. And the mechanical shutter 16
The output of the AE integrating circuit 44 begins to decrease at the point in time when the optical closing time of the AE reaches near the readout timing of the image sensor, and the point in time when the optical closing time of the mechanical shutter 16 comes before the readout timing of the image sensor Thus, the output (integrated value) of the AE integrating circuit 44 decreases in proportion to the amount of movement of the shutter drive pulse of the mechanical shutter 16.

At the time of adjusting the mechanical shutter, there is a margin so that the optical closing of the mechanical shutter 16 is completed before the readout timing of the image sensor based on the change of the integrated value as shown in FIG. adjust. After the mechanical shutter 16 is adjusted, the electronic shutter is adjusted. Hereinafter, the adjustment procedure of the electronic shutter will be described.

The electronic shutter drives the image sensor so as to have an accumulation time corresponding to, for example, 1/512 second (the maximum speed that can be controlled by the camera using the mechanical shutter 16), and a reference luminance box or the like is used. The light source at the base of the light quantity is imaged. Then, an integrated value (reference integrated value) of the output signal read from the image sensor is obtained. Thereafter, while changing the exposure start position (corresponding to the charge accumulation start timing) of the electronic shutter, the same light source is imaged using both the mechanical shutter 16 and the electronic shutter, and the signal integrated value of the image sensor is obtained.

First, the integrated value of the image pickup signal obtained by using only the electronic shutter without using the mechanical shutter 16 (hereinafter referred to as the integrated value)
It is called the reference integrated value. ) Is compared with the signal integrated value obtained by using the mechanical shutter while changing the exposure start position (charge accumulation start timing) of the electronic shutter, and the signal integrated value indicating the value closest to the reference integrated value is obtained. The exposure start position is set as a reference position of the electronic shutter.

After performing such setting, 1/512
When performing an exposure longer than a second, the exposure start position may be shifted forward by an amount of time to lengthen the exposure start position with reference to the reference position of the electronic shutter. By the way, as described with reference to FIGS. 3 and 4, when the mechanical shutter 16 and the electronic shutter are used together, the solid-state imaging device 1
No light is incident on the solid-state image sensor 8, but no smear occurs. However, when the exposure period is controlled only by the electronic shutter, the light is incident on the solid-state imaging device 18 even after the end of the charge accumulation time by the electronic shutter (after the end of exposure). Smearing continues. Therefore, in order to adjust the electronic shutter with higher accuracy, it is desirable to use data from which smear correction has been performed and smear components have been removed.

Next, an example of smear correction will be described. When light is incident on the light receiving surface of the solid-state imaging device 18 through the imaging lens 12, a signal charge is gradually generated in each photoelectric conversion element of the solid-state imaging device in accordance with the intensity of the light incident on that portion. Thus, the signal charges accumulated for a certain period of time are simultaneously transferred to the vertical transfer CCD by the read gate pulse applied from the image pickup drive circuit, and are vertically transferred by application of the vertical transfer pulse. The signal charge transferred to the final stage of the vertical transfer CCD is transferred to the horizontal transfer CCD, and is taken out as a signal voltage via an output unit by applying a horizontal transfer pulse.

Normally, the image pickup driving circuit outputs a readout gate pulse synchronized with the vertical drive pulse (VD), and reads out an image pickup output signal every readout cycle Tv. In this case, if the electronic shutter value (Te) is set faster than the read cycle Tv in accordance with the calculation of the exposure value, a shutter gate pulse for discharging unnecessary charges is read out before the application of the read gate pulse. Unnecessary charges are applied to the gate and are swept away by the CCD substrate. Then, the signal charges accumulated during the predetermined charge accumulation time Te indicated by the electronic shutter value are read by the read gate pulse.
In this way, the read data is integrated for all pixels to obtain light amount data for one screen.

On the other hand, when measuring smear, the read gate pulse output every read cycle Tv is forcibly turned off, and the signal charge of the photoelectric conversion element is transferred to the vertical transfer CCD (transfer path). Without shifting, only the vertical transfer CCD and the horizontal transfer CCD are driven to take out output signals from the output unit. As described above, the imaging output signal obtained with the read gate pulse turned off does not include the component of the signal charge accumulated in the photoelectric conversion element, but includes only the smear component leaked into the vertical transfer CCD. In this way, the read data is integrated for all pixels, and smear for one screen is measured.

As described above, after the read gate pulse is stopped and smear data is obtained, an image is taken using an electronic shutter as usual, and the obtained integrated data (data including smear) is obtained from the obtained smear data. By subtracting the integrated value (smear data), an integrated value from which the smear component has been removed can be obtained. As described above, by performing the adjustment of the electronic shutter using the data from which the smear component has been removed, the adjustment can be performed with higher accuracy.

According to the method of adjusting the mechanical shutter of an electronic camera according to the present embodiment, it is possible to perform adjustment so as to surely close the mechanical shutter in the vicinity immediately before the readout timing of the image pickup device. The time during which unnecessary charges are accumulated is short, and generation of smear (noise) can be suppressed. Further, once the application timing of the shutter drive pulse is determined, there is an advantage that the accumulation time of the image sensor can be controlled only by the exposure start timing of the electronic shutter.

Next, another embodiment of the present invention will be described. Even if the mechanical delay of the mechanical shutter 16 has a mechanical difference, the mechanical difference should fall within a certain range. Therefore, as shown in FIG. 7, the mechanical delay of the mechanical shutter falls within a range defined by the shortest and the longest, assuming the shortest and the longest mechanical delay of the mechanical shutter that varies between individuals. Based on this assumption, the shutter drive pulse application timing (shutter drive start position) is set to a timing at which it is estimated that the shutter will be optically closed before the readout timing of the image sensor.

After this setting, the electronic shutter is adjusted in the same procedure as the method described above. At this time, the same applies to the use of data from which smear components have been removed.
According to such a method, there is an advantage that a fine adjustment step of the mechanical shutter can be omitted, and the adjustment operation is simplified. It is desirable that the adjustment of the electronic shutter in each of the above-described embodiments is performed not only for one shutter time but also for a plurality of different shutter times. This is because the adjustment of the electronic shutter can be performed only at certain limited time steps (for example, in units of one horizontal drive cycle), and there is a possibility that an error may occur if only one point is adjusted. Therefore, if the adjustment is performed at two or more points, the error can be reduced and the adjustment can be performed with higher accuracy.

When a variable aperture is used in the electronic camera 10 like the aperture 14 in FIG. 1, it is desirable to adjust the aperture by changing the aperture. This is because the center of the stop does not always coincide with the center of the optical axis, and depending on the system, the stop may be located at a position shifted from the center of the optical axis, and the stop may be located due to an assembly error. This is because the shutter may not always be located at the center of the optical axis, and the shutter may not always be symmetrical about the center.

[0049]

As described above, according to the method for adjusting the mechanical shutter of an electronic camera according to the present invention, the variation of the exposure control time caused by the mechanical delay of each mechanical shutter is controlled by applying the mechanical shutter drive pulse. The timing or the charge accumulation start timing of the electronic shutter is adjusted by shifting the timing back and forth as appropriate, so that the adjustment jig for the mechanical shutter, which was conventionally required, becomes unnecessary, and the function of the camera is eliminated. The mechanical shutter can be adjusted easily and with high accuracy by utilizing.

Further, according to the present invention, it is possible to provide an electronic camera capable of performing high-precision AE and photographing without increasing the accuracy of the mechanical shutter more than necessary.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electronic camera to which the present invention is applied.

FIG. 2 is a timing chart showing a photographing sequence at the time of actual photographing;

FIG. 3 is a timing chart showing a sequence at the time of preview and at the time of AE.

FIG. 4 is a timing chart showing a relationship between an exposure time and a readout period when an electronic shutter is used, which is used to explain the cause of smearing.

FIG. 5 is a timing chart showing how to set a shutter time that does not exceed a vertical drive cycle.

FIG. 6 is a graph showing a relationship between application timing of a mechanical shutter drive pulse and a signal integrated value of an image sensor.

FIG. 7 is a timing chart used to describe another embodiment of the shutter adjustment method for an electronic camera according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Electronic camera 12 ... Photographing lens 14 ... Aperture 16 ... Mechanical shutter 18 ... Solid-state image sensor 20 ... Analog signal processing circuit 22 ... A / D converter 28 ... D / A converter 30 ... Liquid crystal monitor 36 ... Control circuit 38 ... Central processing unit (CPU) 44 ... AE integrating circuit 46 ... Histogram generator 48 ... Digital signal processing circuit

Claims (6)

[Claims] A mechanism for instructing a closing operation of a mechanical shutter in an electronic camera having both an electronic shutter for controlling a charge accumulation time of an image sensor and a mechanical shutter capable of blocking / opening an optical path incident on the image sensor. After applying the shutter drive pulse, the deviation from the specified exposure time caused by the variation between the mechanical delays until the mechanical shutter actually closes is corrected by adjusting the application timing of the mechanical shutter drive pulse. How to adjust the mechanical shutter of an electronic camera. 2. An electronic shutter for controlling a charge accumulation time of an image pickup device, and a mechanical shutter capable of blocking / opening an optical path incident on the image pickup device. In an electronic camera that defines the start of exposure and the end of exposure by closing the mechanical shutter, the mechanical delay from the application of the mechanical shutter drive pulse that instructs the closing of the mechanical shutter until the mechanical shutter actually closes A mechanical shutter adjustment method for an electronic camera, wherein deviation from a specified exposure time caused by variation between individuals is corrected by adjusting charge accumulation start timing by an electronic shutter. 3. The adjustment of the application timing of the mechanical shutter drive pulse according to claim 1 or the adjustment of the charge accumulation start timing by the electronic shutter according to claim 2 is performed after the mechanical shutter is incorporated in the camera. To adjust the mechanical shutter of the electronic shutter. The adjustment of the application timing of the mechanical shutter drive pulse in claim 1 or the adjustment of the charge accumulation start timing by the electronic shutter in claim 2 is performed by using only the electronic shutter so that the exposure time is adjusted to a predetermined accumulation time. Controlling an image of a light source whose light amount is known in advance, and integrating output signals read out from the image sensor at this time to obtain first integrated data; and exposing using an electronic shutter and a mechanical shutter together. Controlling the time to image the light source, integrating the output signal read from the image sensor at this time to obtain second integrated data, and comparing the first and second integrated data. Adjustment of the application timing of the mechanical shutter drive pulse or adjustment of the charge accumulation start timing by the electronic shutter Electronic camera mechanical shutter adjustment method, wherein the dividing. 5. The method according to claim 1, wherein at least two or more types of accumulation times corresponding to a plurality of shutter times are adjusted in application timing of the mechanical shutter drive pulse or adjustment of charge accumulation start timing by the electronic shutter. The method for adjusting a mechanical shutter of an electronic camera according to claim 4. 6. When the electronic camera has a variable aperture, the F-number of the aperture is changed to adjust the application timing of the mechanical shutter drive pulse for each of the at least two or more apertures, 5. The method according to claim 4, wherein the timing of starting charge accumulation is adjusted.