JPH09163237A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image with proper exposure even after the change of driving speed in an imaging device by estimating the electronic shutter value of the imaging device after the change of the driving speed of the imaging device and setting it. SOLUTION: At first, the electronic shutter value Sf of CCD by finder display at present is obtained (step 11). Then, CCD driving speed is changed (step 12) from driving speed in a finder to the one in a still image. Moreover, the proper electronic shutter value Sx at the time of picking-up a still image is estimated by the electronic shutter value Sf obtained in the step 11, CCD driving speed A in the finder and CCD driving speed B in still image pickup. The electronic shutter value Sx at this time is estimated by Sx=Sf×B/A×P1 where P1 is a certain specified positive number. Then, the electronic shutter value of CAD is set (step 14) to Sx which is obtained in the step 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device capable of changing a driving speed of an image pickup device, and more particularly to electronic shutter value control of an image pickup device in an image pickup device including a computer and an image pickup unit connected thereto.

[0002]

2. Description of the Related Art When a computer has a connection terminal that conforms to the PCMCIA standard, the PCMCI is connected to this connection terminal.
It is common to insert and use a card-shaped unit having various functions such as a fax card and a memory card having a connection terminal conforming to the A standard. On the contrary, a card having a connection terminal conforming to the PCMCIA standard can be used by connecting to various computers having the connection terminal.

Since the PCMCIA standard connection terminal transfers data at high speed, it is effective as an input means to a computer for an image requiring a large amount of data.

FIG. 4 shows an example of an image pickup system including an image pickup unit having a PCMCIA standard connection terminal and a computer having the same standard connection terminal.

In FIG. 4, 41 is an image pickup unit having a PCMCIA standard connection terminal, 42 is a computer, 4
Reference numeral 3 denotes a PCMCIA standard connection terminal of the computer 42, and 44 denotes a display device such as a liquid crystal display of the computer 42.

In the image pickup unit 41, 401 is a lens unit, 402 is a CCD (image pickup element), 403 is an A / D converter, and 404 is digital signal processing (DS).
P), 405 is a FIFO (first in, first out) memory,
406 is a timing generator (TG), 407 is a control unit of the imaging unit, 408 is automatic exposure (AE)
The control unit 409 is an automatic white balance (AW
B) Control unit, 410 indicates a connection terminal of PCMCIA standard.

The procedure for performing imaging with the imaging system of FIG. 4 is as follows. The imaging unit 41 is a computer 42
In the case where the image pickup unit 41 is connected to, the image pickup instruction is given from the computer 42, and then the image pickup is performed by the lens unit 401 and the CCD 402 incorporated in the image pickup unit 41. At this point in time, the captured image is accumulated in the CCD 402 as electric charges. Next, the picked-up image is taken out from the CCD 402 for each pixel and is sequentially converted into digital data by the A / D converter 403. The data converted to digital data is
At the same time, the DSP 404 uses the luminance signal and the color difference signal
The image signals are converted into image signals of various formats such as GB signals, and are sequentially stored in the FIFO memory 405. CC
The picked-up image is taken out from the D402 and is stored in the FIFO memory 4
The timing of accumulation in 05 is controlled by the timing generator 406. The exposure value of the captured image and the data for white balance are acquired when passing through the DSP 404, and are taken into the AE control unit 408 and the AWB control unit 409, respectively.

The exposure value and the white lance data taken into the AE control unit 408 and the AWB control unit 409 are taken into the computer 42 through the connection terminals 410 and 43, and in the computer 42, the electronic shutter value of the CCD 402 and the white balance. Calculate the parameters of. By sending these data as an instruction to the AE control unit 408 and the AWB control unit 409, the AE control unit 408 can generate C
The electronic shutter value of the CD 402 is controlled so that the captured image has an appropriate exposure, and the AWB control unit 409
Controls the captured image to have an appropriate color. CC
Electronic shutter value of D402 and timing generator 4
The exposure time of the CCD 402 is obtained by multiplying the unit width of the specific clock generated by 06.

On the other hand, on the computer 42 side, a FIFO
The image data stored in 405 is connected to the connection terminals 410, 43.
Take in through. By storing the image data captured at this time in the memory in the computer 42, a still image can be saved. On the other hand, by sequentially displaying the images captured from the imaging unit 41 on the liquid crystal display 44 on the computer 42,
The computer 42 can also be used as a finder. The user can pick up an appropriate still image by confirming the composition and size of the object to be picked up with the finder and giving an instruction to pick up an image with a keyboard or mouse of the computer at a favorite pattern.

By the way, since the liquid crystal display of a computer generally has a low resolution, it is often possible to display only a limited number of colors. Further, in order to use the computer 42 of FIG. 4 as a finder, it is desirable to display as many images as possible per unit time. Therefore, the images captured by the computer 42 from the imaging unit 41 may have a slightly lower resolution. , The amount of data per image should be as small as possible.

On the other hand, when a still image is picked up by the image pickup system of FIG. 4, it may be considered that the picked-up image is finally viewed on a display having a higher resolution, so that the image having the highest possible resolution is obtained. It is better to be asked.

Therefore, in the image pickup system of FIG.
When capturing a still image, an image signal having a higher resolution than that used when using as a finder is fetched from the image capturing unit 41 to the computer 42. For example, when the liquid crystal display 44 of the computer is in the 256-color palette mode, the image data to be captured has a data amount of 8 bits per pixel. On the other hand, when capturing a full-color still image, the captured image data is 16 bits per pixel, or 24 bits per pixel.
It is the amount of data in bits.

Here, the computer 42 is connected to the connection terminal 41.
Since the amount of data taken in through 0, 43 per unit time is constant, when capturing a still image as compared with the case of using it as a finder, the image stored in the FIFO memory 405 will not overflow. To C
The captured image is taken out from the CD 402 and the FIFO memory 4
It is necessary to slow down the clock speed of the timing generator 406 that controls the timing of accumulation in 05.

That is, in the above example, if the amount of data taken in from the image pickup unit by the computer per unit time through the connection terminal is made constant, the timing generator 406 of the timing generator 406 can be used when taking a still image as compared with the case of displaying the viewfinder. The clock needs to be half or one third as fast.

[0015]

In the above-mentioned image pickup system, when the picked-up images are successively displayed on the liquid crystal display 44 in the viewfinder, the AE control section uses the AE data to read the CCD image so that the picked-up images are properly exposed. The shutter value is calculated and set sequentially.

However, when the user gives an instruction to pick up a still image in this state, the speed of the clock of the timing generator 406 is slowed down, so that the CCD as it is.
At the electronic shutter value of 402, the captured image is overexposed.

The present invention has been made under such circumstances, and an object of the present invention is to provide an image pickup apparatus capable of obtaining an image with proper exposure after changing the driving speed of the image pickup element.

[0018]

In order to achieve the above object, in the present invention, an image pickup device is constructed as in the following (1) to (5).

(1) An image pickup apparatus capable of changing the driving speed of an image pickup element, wherein the electronic shutter value deciding means decides an electronic shutter value of the image pickup element before changing the driving speed of the image pickup element; Electronic shutter value estimating means for estimating the electronic shutter value of the image sensor after changing the drive speed of the element, and setting for setting the electronic shutter value estimated by the electronic shutter value estimating means after changing the drive speed of the image sensor And an image pickup apparatus including.

(2) The electronic shutter value estimation means is based on the ratio of the electronic shutter value determined by the electronic shutter value determination means to the drive speed of the image sensor before and after the drive speed of the image sensor is changed. The image pickup apparatus according to (1) above, which estimates the electronic shutter value of.

(3) The electronic shutter value estimation means uses the exposure value of the image sensor before changing the drive speed of the image sensor and the exposure value of any two or more points before changing the drive speed of the image sensor. The image pickup apparatus according to (1), wherein the electronic shutter value of the image pickup element is estimated based on an appropriate electronic shutter value after the drive speed of the element is changed.

(4) The image pickup for electronic viewfinder display is performed before the drive speed of the image pickup device is changed, and the still image is taken after the drive speed of the image pickup device is changed. The image pickup device according to any one of claims.

(5) The image pickup device includes an image pickup unit,
The image pickup apparatus according to any one of (1) to (4) above, further comprising a computer connected to the computer via a PCMCIA standard connection terminal.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to an embodiment of a still image pickup device. The present invention can be implemented not only in the still image capturing device but also in an appropriate image capturing device having a variable image sensor driving speed.

[0025]

[Embodiment 1] (Embodiment 1) Since the still image capturing apparatus of this embodiment has the same hardware configuration as that of FIG. 4, its description is omitted.

FIG. 1 shows an electronic shutter value estimating method and a method for estimating a still image when a user gives an image capturing instruction while a captured image is displayed in the viewfinder on the liquid crystal display in this embodiment. 6 is a flowchart showing a method of setting a value.

First, at step 11, the electronic shutter value Sf of the CCD in the current finder display is obtained. In the present embodiment, if the exposure value is within a certain range, the electronic shutter value Sf takes an appropriate value by the AE control unit included in the imaging system, so that the captured image in the finder display has an appropriate exposure. In the present embodiment, the electronic shutter value takes an integer value of 1 to S, and the electronic shutter value multiplied by the unit width of the specific clock generated by the timing generator becomes the exposure time. When the electronic shutter value is 1, The exposure time is the shortest, and the exposure time is the longest for S.

Next, in step 12, the CCD drive speed is changed from AHz, which is the drive speed in the finder, to BHz, which is the drive speed in the still image. In this embodiment, the still image has a higher resolution than the finder image, so A> B
Becomes

Next, in step 13, from the electronic shutter value Sf obtained in step 11, the CCD drive speed A in the viewfinder, and the CCD drive speed B in still image pickup, an appropriate electronic shutter value for still image pickup is obtained. Guess Sx.

The electronic shutter value at the time of capturing a still image is estimated by the following equation (1).

Sx = Sf × B / A × P1 (1) where P1 is a specific positive value.

When Sx = 0 as a result of the equation (1), Sx =
Let it be 1.

Next, in step 14, the electronic shutter value of the CCD is set to Sx obtained in step 13. Next, in step 15, a still image is captured. Then in step 16 C
The electronic shutter value of the CD is returned to Sf which is the electronic shutter value in the viewfinder display. Finally, in step 17, the CCD drive speed is changed to AHz which is the drive speed in the finder, and the process ends.

As described above, according to this embodiment,
It is possible to obtain a still image with proper exposure regardless of the change in CCD driving speed.

(Embodiment 2) The still image pickup apparatus of this embodiment also uses the same hardware configuration as that shown in FIG.
This embodiment will be described below with reference to FIGS. 2 and 3.

In the first embodiment, if P1 is set to a value not higher than A / B, there is a relation of A> B in CCD driving speeds A and B. Therefore, the electronic shutter value Sf in the finder display and step 13 in FIG. There is a relationship of Sf> Sx between the obtained electronic shutter value Sx in still image capturing.

Since the electronic shutter value Sf can be controlled only up to the maximum value S, the exposure control is disabled when the exposure value is below a certain value in the finder display.

However, even when the exposure control is not possible in the viewfinder display, the exposure may be properly adjusted in the still image pickup.

However, in the first embodiment, since the electronic shutter value in the finder display takes a value of 1 to S,
The maximum value of the electronic shutter value in still image capturing is smaller than S, and the exposure range of the captured image controllable by the electronic shutter is narrowed.

Therefore, in the present embodiment, when the exposure control in the finder display is impossible, an electronic shutter capable of capturing a still image with an appropriate exposure when the exposure value of the captured image in the finder display is a certain value or more. The method of guessing the value is shown.

2 is similar to FIG. 1, in the image pickup system of FIG. 4, an electronic image when a still image is picked up by a user giving an image pickup instruction from a state in which the imaged image is displayed in the viewfinder on the liquid crystal display. 6 is a flowchart showing a method of estimating a shutter value and a method of setting the estimated value.

First, at step 21, the electronic shutter value Sf of the CCD in the current finder display is obtained. The electronic shutter Sf has the same characteristics as those in the first embodiment.

Next, at step 22, it is judged from the electronic shutter value Sf in the finder display whether or not the exposure control is impossible in the finder display. When the electronic shutter value Sf obtained in step 21 is not S (that is, Sf
Since the exposure range is controllable by the method of the first embodiment (<S), the process proceeds to step 29, and the electronic shutter value Sx for still image capturing is obtained according to the method of the first embodiment. When the electronic shutter value Sf obtained in step 21 is S, it means that the exposure range cannot be controlled by the method of the first embodiment. Therefore, the electronic shutter value Sx is obtained by the following method.

First, at step 23, the exposure value Ex of the captured image in the finder display state is obtained. Next, step 24
And the CCD drive speed is A which is the drive speed in the viewfinder.
Change from Hz to BHz, which is the driving speed for a still image. Next, in step 25, an appropriate electronic shutter value Sx for capturing a still image by the method described below is estimated from Ex obtained in step 23.

First, when the exposure value Ex is below a certain value, C
Since the exposure range of the captured image cannot be controlled after the CD drive speed is changed, the electronic shutter value Sx is set to the maximum value S.
And When the exposure value Ex is a certain value or more, the following procedure is followed. FIG. 3 shows a method for estimating an appropriate electronic shutter value Sx when capturing a still image in this embodiment. In FIG. 3, E1 and E2 are exposure values at arbitrary two points in the finder display before changing the CCD drive speed, and
1 and S2 are electronic shutter values with which a captured image with an appropriate exposure can be obtained when a still image is captured by changing the CCD drive speed slowly when the exposure values in the finder display are E1 and E2, respectively.

At this time, the appropriate electronic shutter value Sx for capturing a still image is the exposure value in the viewfinder display in the horizontal axis direction in FIG. 3, and the electronic shutter value for obtaining an appropriately exposed image in the vertical axis direction. In the space where
It is on a straight line passing through 1) and (E2, S2), and the exposure value in the finder display is set to Ex.

The formula is as follows.

Sx = (S1−S2) × (Ex−E1) / (E2−E1) + S2 (2) In the present embodiment, the exposure value in the finder display of arbitrary two points and the appropriateness of each exposure value. Although the electronic shutter value at which various exposures are obtained is the sample point, the electronic shutter value Sx in the still image capturing can be obtained by the same method even when the sample points are three or more.

For example, the sample points are (E1, S1), (E2,
If the three points S2) and (E3, S3) (E1 <E2 <E3) are set, the exposure value Ex in the finder display is first E.
When x <E2, (E1, S1), (E2, S2) are used to make the estimation, and when the exposure value Ex is Ex> E2, (E2, S2), (E3, S3) are used. You can guess. If the number of sample points is increased, it is possible to more accurately estimate the electronic shutter value.

Steps 26 to 29 are the same as steps 14 to 17 of the first embodiment.

As described above, according to this embodiment,
It is possible to more accurately estimate the electronic shutter value in still image capturing.

In the embodiment, the image pickup unit and the external device are connected by wire for communication, but the present invention is not limited to this, and may include wireless communication of image signals and commands.

Further, in this embodiment, the electronic shutter value estimating means estimates the electronic shutter value by calculation, but it may be realized by using a ROM or the like.

[0054]

As described above, according to the present invention,
The electronic shutter value of the image sensor after changing the image sensor drive speed can be set so that the captured image has an appropriate exposure.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the operation of the first embodiment.

FIG. 2 is a flowchart showing the operation of the second embodiment.

FIG. 3 is an explanatory diagram of an electronic shutter value estimation method according to the second embodiment.

FIG. 4 is an explanatory view of a conventional example.

[Explanation of symbols]

 41 imaging unit 42 computer 43 PCMCIA standard connection terminal 402 CCD 407 control unit 408 automatic exposure control unit 410 external connection interface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Sono 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masayoshi Sekine 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation

Claims (5)

[Claims] 1. An image pickup apparatus capable of changing a driving speed of an image pickup element, wherein the electronic shutter value deciding means decides an electronic shutter value of the image pickup element before changing the driving speed of the image pickup element, and the image pickup element. Electronic shutter value estimating means for estimating the electronic shutter value of the image sensor after the change of the driving speed of the image pickup device, and setting means for setting the electronic shutter value estimated by the electronic shutter value estimating means after the change of the drive speed of the image sensor. An imaging device comprising: 2. The electronic shutter value estimation means of the image pickup device is based on the electronic shutter value determined by the electronic shutter value decision means and the ratio of the drive speed of the image pickup device before and after the change of the drive speed of the image pickup device. The image pickup apparatus according to claim 1, wherein the electronic shutter value is estimated. 3. An electronic shutter value estimating means for the image pickup device with respect to an exposure value of the image pickup device before changing the drive speed of the image pickup device and an arbitrary exposure value of two or more points before changing the drive speed of the image pickup device. The image pickup apparatus according to claim 1, wherein the electronic shutter value of the image pickup device is estimated based on an appropriate electronic shutter value after the change of the driving speed of the image pickup device. 4. The method according to claim 1, wherein an image for electronic viewfinder display is taken before changing the driving speed of the image pickup device, and a still image is taken after changing the driving speed of the image pickup device. Item 4. The imaging device according to any one of items 3. 5. The image pickup apparatus according to claim 1, further comprising an image pickup unit and a computer connected to the image pickup unit via a PCMCIA standard connection terminal. Imaging device.