JPS6025390A - Image pickup system in electronic camera device - Google Patents

Abstract

PURPOSE:To convert a dark object into a sharp and bright picture without flicker by lighting a flashing device in interlocking with a shutter button so as to sensitize all picture elements in response to the object image thereby obtaining a still picture signal. CONSTITUTION:In depressing a shutter button 5, a pulse signal is generated and given to a control circuit 6, from which various control pulses are outputted. A drive circuit 8 obtaining this control pulse gives a high frequency drive pulse to a solid-state image pickup element 4 so as to zero residual electric charges remained on the photosensitive face. The control pulse is fed to a shutter 3 to open the shutter 3 and also fed to a flashing device 7, which is lighted to make an object image 1 bright so as to sensitize the photosensitive face of the image pickup element 4 via an image pickup lens 2. The picture output is extracted at an output terminal 11 via an amplifier 9 and a frame memory 10.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention is directed to a 1πi method in an electronic camera device that captures 1q still images using a solid-state imaging element.

[Technical background of the invention and its problems] Recently, solid-state image sensors such as COD and MOS have been used to record still images on frame memories such as magnetic disks and semiconductor media, and then reproduce them on television. Research and development of electronic cameras '41 that display images by John N, etc., is being actively conducted.

In such an electronic camera device, the same solid-state imaging device as in a normal home video camera can be used in principle.

However, if you use the same camera system as a normal home video camera, the image of the subject will be continuously formed on the photosensitive surface of the solid-state image sensor, making it difficult to obtain a still image. The practice is to extract and record only one stroke of one field. However, with this method, it is difficult to capture the subject image at an arbitrary time, and with normal television scanning,
' A shutter time of 60 seconds was required, making it impossible to capture the instantaneous image of the subject. Furthermore, it is difficult to use a flash device like that used in photographic cameras, and even when used in a single flash, it does not synchronize with television scanning, so it has the disadvantage that it is only possible to produce images with uniform brightness.

On the other hand, in a normal television system, one frame image is formed by two fields of images, and by performing interlacing, the number of scanning lines is doubled to 525, improving vertical resolution. Therefore, if one field of image is extracted as described above, the vertical resolution is reduced to 1772, and there is a problem that a clear image cannot be obtained.

Furthermore, when attempting to form a still image using one frame of image, there is a drawback that flicker occurs when the subject is moving, making the still image extremely difficult to see. In other words, if the subject is moving, the first. Since the pixels in the second field are slightly different, flicker occurs in the still image, making it difficult to see as a still image.

When a solid-state image sensor is used, the charge accumulation time due to light incident on each pixel on the photosensitive surface is divided into field accumulation equivalent to one field (^) and l norm accumulation corresponding to two fields. There are two methods, but in either case, ff11. Since light at different times enters the field of wS2, when the subject is moving, the signals received by 1q will differ, making the above-mentioned drawback unavoidable.

[Objective of the Invention] The object of the present invention is to be able to take a clear still image using a flash device and with sufficient brightness even for a dark subject, and to be able to capture a still image without flicker even when a single frame still image is obtained by interlacing. An object of the present invention is to provide an imaging method for an electronic camera device that can obtain good images.

[Summary of the Invention] The present invention erases residual charges accumulated in all pixels on the photosensitive surface of a solid-state image carrier in conjunction with the shutter button, and then turns off the flash device to display the object image for a certain period of time. Then, signal charges corresponding to the subject image are read out from these pixels to remove the still image signal. In this way, the exposure time is substantially determined by the light emission time of the flash device, and since this time is generally very short, 1q of clear still images with sufficient brightness can be obtained even for fast-moving subjects. Furthermore, when interlacing, the first Since images at the same time point are obtained in the second field, no flicker occurs.

[Embodiment of the Invention] FIG. 1 shows the configuration of an electronic camera device according to an embodiment of the invention. In the figure, the solid-state image sensor 4 is, for example, a COD, and a shutter 3 is provided in front of its photosensitive surface. A subject image 1 is formed on a CCD 4 via an imaging lens 2 when the shutter 3 is activated. The shutter 3 is activated by the control circuit 6 by pressing the shutter button 5.
Opening/closing is controlled by control signals generated from the

On the other hand, a flash device [7 (for example, an electronic flash device) for illuminating the subject is provided, and this flash device 7 also operates based on a control signal from the control circuit 6.

The electrical operation of the CCD 4 is performed by a driving pulse Σ generated by the driving circuit F88, and the output horn of the image 19 is connected to the output terminal 1 via the amplifier 9J5 and the frame memory 10.
It is taken out at 1.

Photographing of the subject 1 elephant 1 is carried out by aiming at the subject and pressing the button 5 in the same way as with a normal still camera using a frame. When the shutter button 5 is pressed, pulse signals are generated, each of which is applied to the control circuit 6.

The control circuit 6 uses this pulse signal to control various VIs.
Generates pulses, one of which is the extrusion control signal 1
It is also added to the drive circuit 8. The drive circuit 8 outputs high-frequency drive pulses to the CCD during this exposure control signal input period.
Supply to 4. As a result, the residual charge remaining on the photosensitive surface of C0D4 is removed all at once, and each pixel on the photosensitive surface becomes
The charge becomes zero. Next, a shutter control signal is generated from the control circuit 6 and supplied to the shutter 3. During this shutter control I signal period, the shutter 3 is opened and the object image 1 is focused on the photosensitive surface of the CCD 4 by the imaging lens 2. In this state, a pulse is given from the control circuit 6 to the flash device 7. The flash device 17 emits light, thereby exposing the photosensitive surface to the subject image 1.

As shown in FIG. 2, the CCD 4 has a large number of pixels arranged two-dimensionally to form a photosensitive surface. Each pixel PIJ (+-
1-400. j-1 to 500) are usually formed by photoelectric conversion elements such as photodiodes, and 4 in the horizontal direction.
00 pixels, and 500 pixels are arranged in the vertical direction.

Further, a vertical transfer section CVi is provided adjacent to each row of pixels Plj. Further, a horizontal transfer section CH1fiu is provided adjacent to the lower end of the vertical transfer section CVi, and an output section 21 and an output terminal 22 are provided at the left end thereof.

Signal charges corresponding to the brightness and darkness of the subject image 1 are simultaneously accumulated in all pixels PtJ by the light emission of the flash device 7, and then, when the shutter 3 is closed, light to the photosensitive surface of the CCD 4 is blocked, so that the signal of each pixel P+J is Charge accumulation ends. The signal charges accumulated in each pixel Pij are transferred to the vertical transfer section CV i at every other pixel in the vertical direction, that is, first, the signal charges of odd-numbered pixels are transferred to the vertical transfer section CV i by a transfer pulse from the drive circuit 8, and the signal charges are transferred to the vertical transfer section CV i for one line. The data are sequentially sent to the horizontal transfer unit CH.

The signal charge sent to the horizontal transfer section CH is transferred in the horizontal direction by a transfer pulse from the drive circuit 8, and is taken out from the output terminal 22 via the output section 21. Both f! of the odd field due to C! The signal will be 19 times.

When all the signals of the odd-numbered pixels are read out from the output terminal 22, the remaining signals of every other pixel in the vertical direction,
That is, even-numbered pixel signals are sent all at once to the vertical transfer unit CVI. Then, as before, the horizontal transfer section (H) is taken out from the output terminal 22 via the output section 21. This results in the image signal of the field being obtained. That is, the signal stored in each pixel is The charges are extracted by so-called interlaced scanning to obtain one frame of still image signal.

In this way, the static 1 rain signal 19 output from COD 4 is guided to amplifier 9, amplified, and then supplied to frame memory 10. The frame memory 1o enters the recording mode by a control signal from the control circuit 6, and records the aforementioned two frames of image signals. The signals recorded in the frame memory 10 are read out continuously and taken out to the output terminal 11 as still image signals.

FIG. 3 shows a time chart 1 showing the previous operation. When the pulse signal shown in FIG. 5(a) is obtained by the shutter button 5, the pulse signal shown in FIG. The discharge pulse shown in b) is applied, and the signal charges remaining in all pixels PIJ are simultaneously transferred to the vertical transfer section OVi and discharged. Next, Figure 5 (C)
A shutter control signal having a pulse width of, for example, 1/60 seconds is supplied to the shutter 3, and the shutter 3 is opened.

Next, while the shutter 3 is open, a trigger pulse shown in FIG. 3 ((1)) is supplied to the flash device 7, the flash device 7 emits light, and all pixels PIJ of 500×400 are exposed to light at the same time.

After the flash device 7 finishes emitting light and the shutter 3 closes, the signal charge accumulated in each pixel Plj is read out by interlacing, and as shown in FIG. A video signal of one field and a video signal of a second field consisting of even-numbered pixels are obtained.

The output of the CCD 4 is amplified by an amplifier 9 and then applied to a frame memory 70. At this time, the frame memory 10 enters the recording mode by a control signal from the control circuit 6, and records the above-mentioned one frame video signal. The signals recorded in the frame memory 10 are read out continuously, and 1q still image signals are sent to the output terminal 11. Note that a normal magnetic disk, semiconductor memory, etc. are used as the frame memory 10, but the description will be omitted here.

As explained above, according to the present invention, the residual charge on the photosensitive surface of the solid-state image sensor is erased, and then the flash device is caused to emit light.
A clear still image can then be obtained by reading out the signal charges.

In other words, all the pixels PIJ formed on the photosensitive surface of the solid-state image sensor are simultaneously exposed to light for a short period of time, and one frame of image can be made up to 1q by interlacing, so it is possible to image fast-moving subjects or dark subjects well. It becomes like this. In this case, since the image does not move between the first field and the 27th field, unsightly flicker does not occur, and a high-quality signal can be obtained.

Furthermore, since one field is scanned at 59.94 Hz and a still image of one frame can be obtained by interlacing, it is possible to obtain a still image of one frame with a one-day delay line and without using a special television receiver. The advantage is that high-resolution still images can be easily enjoyed even when using a home television receiver.

In addition, when the pixels are arranged in an analog manner and there are no clear divisions, such as in an image pickup tube, there will be differences in level in each field, which causes flicker, but in this invention, all pixels Pij Since they are formed independently, there is an advantage that the same signal can be obtained with no difference in output level for a plurality of field images.

This invention can be implemented with various modifications; for example, in the above explanation, the shutter opens and the flash device emits light after the residual charge is erased; however, this order is not limited to this. , the residual charge may be erased immediately before the flash device emits light. In this way, the shutter time can be set accurately purely electronically, regardless of whether the mechanical shutter is opened or closed.

Furthermore, although the above embodiments have been described using a COD as the solid-state image sensor, it goes without saying that a CPD, O, ID, etc. may also be used.

It is also possible to obtain high-resolution color still images by providing a color filter array on a solid-state image sensor and utilizing the principle of a single-chip color camera.

Furthermore, when using a magnetic disk as a frame memory, if the magnetic disk is turned so that one frame of image is recorded per rotation of the magnetic disk, 525 horizontal synchronization pulses can be continuously recorded at equal intervals on one rotation of the magnetic disk. There is an advantage. When conventionally recording one field over one rotation of a magnetic disk, five horizontal sync pulses are lined up at 262 degrees per rotation, resulting in a 0.5H discontinuity that cannot be displayed on a normal television receiver. In this case, it is necessary to perform corrections such as switching using a 0.5H delay line (), which has the disadvantage of complicating the device, but if the above method is used, such corrections can be made. Unnecessary yelling.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing an example of a solid-state tllfil element used in the invention, and FIG. 3 is a waveform diagram for explaining the operation of the embodiment. It is. DESCRIPTION OF SYMBOLS 1... Subject image, 2... Imaging lens, 3... Shutter, 4... Solid-state image device (COD), 5... Shutter button, 6... Control circuit, 7... Flash device, 8
...Drive circuit, 9...Amplifier, 10...Frame memory. Applicant's agent Patent attorney Takehiko Suzue

Claims (2)

[Claims] (1) An electronic camera that obtains still images using a solid-state image element that has a photosensitive surface made of a two-dimensional array of many pixels.
In Zlt, a flash device is provided to illuminate the subject, and after erasing residual charges accumulated in all pixels on the photosensitive surface by operating the shutter button, the flash device is activated to illuminate all pixels on the photosensitive surface. An imaging system for an electronic camera device, characterized in that a still image signal is obtained by exposing a subject to light according to the subject, and then reading out signal charges corresponding to the subject image from all pixels on the photosensitive surface. (2) The first aspect of the present invention is characterized in that the signal charge is read out from the photosensitive surface by dividing it into a plurality of fields by interlacing to obtain a still image signal of one frame.
Imaging method in the electronic camera device described in .