JPS58161587A - Still image shooting system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that captures still images and electrically records and reproduces them.

As a device for taking still images, a so-called photograph, which is an optical image printed on a film, is generally used, but in recent years, this has been taken with an electric imaging device. In the imaging and recording system, 1 is the lens.

2 is a shutter, 3 is an image sensor, 4 is a scanning circuit, 5 is a signal processing circuit, 6 is a magnetic recording head, 7 is a magnetic tape, the image sensor 3 is similar to that for a television camera, 6.7 are similar to those of audio cassette tape recorders. The imaging and recording operations are as follows:
The shutter is opened for a certain period of time (about the same time as an optical camera) to expose an optical image on the surface of the image sensor, and a surface charge corresponding to the optical image is accumulated. After the shutter closes, it scans at a slow speed (approximately 1/100th that of a television camera) commensurate with the speed that the recording thread can follow, and the obtained Eirin signal is converted into an analog signal or converted into a digital signal and then used as a magnetic signal. Record on tape.

Next, in the reproduction system, 8 is a reproduction head.

9 is a signal processing circuit, 10 is a buffer memory, and 11 is a picture monitor. During playback, the magnetic tape is read out at the same slow speed as during recording, and the obtained signal is
transfer to buffer memory. After all the image signals for one frame have been transferred to the buffer memory, this buffer memory is repeatedly read out at the normal television signal speed to create a television still image signal, which is displayed on a picture monitor.

This method is attractive because it does not require film development or printing, and allows you to easily enjoy images on your home TV receiver at a low second printing cost. There is a next problem that must be solved.

The first problem is that it takes a long time (approximately 100 times as long as a television camera) to scan the surface charge of the image sensor, which increases dark current. Dark current is a type of leakage current inside the image sensor that is unrelated to the optical system, and is converted into charge in the storage capacitor in proportion to time and is read out together with the signal charge during scanning. Since the amount of accumulated charge is proportional to time, the dark current is relatively small at the top of the screen, which is scanned for a short period of time, and is large at the bottom, where it is scanned last. As described above, since the dark current is not uniform within the screen, a brightness gradient or a color gap occurs in the reproduced image*, or in the case of a color image.

The second problem, which is also common to television cameras, is that unnecessary fixed signals unrelated to the image signal are likely to be mixed into the output signal of the image sensor. They are,
For example, various pulse components jump in the scanning circuit, shading, or especially when using a solid-state image sensor, vertical stripe noise called fixed bang noise, countdown noise generated in the process of creating clock pulses, etc. It is. These unnecessary fixed signals may be suppressed by various methods, but in order to replace the conventional camera, compactness is an essential condition, and redundant devices must be eliminated as much as possible.

The purpose of the present invention is to solve the problems of dark current and dark current slope due to the above-mentioned low-speed scanning and other unnecessary fixed signal problems. After the recording is completed, the image sensor is read out and scanned again at the same speed without exposure, and the dark current and other unnecessary fixed signals obtained at that time are recorded. During playback, the true video signal is obtained by subtracting the dark current and unnecessary fixed signals read from the tape from the video signal read from the tape and stored in the buffer memory, and then stored back into the buffer memory. The purpose is to display the correct image on a picture monitor by repeatedly reading out images at the speed of a television signal.

More specifically, it is preferable that dark current and unnecessary fixed signals be read out from the image sensor and scanned at the same speed and in the same order as the readout scan of the video signal. If you do this,
Both dark current and other unnecessary fixed signals can be completely canceled. Furthermore, if it is sufficient to cancel even other unnecessary fixed signals other than dark current, the readout scanning speed and order may be different from the signal readout.

This is because nothing other than dark current is time-dependent.

Further, reading out the dark current and unnecessary fixed signals may be performed prior to reading out the exposure and image signals. It should be noted that an IC memory (RAM) or a magnetic disk memory is suitable as the /<rough memory.

As described above, according to the present invention, both the problem of dark current and its gradient due to low-speed readout scanning and the problem of other unnecessary fixed signals are eliminated, and a still image photographing system can be realized.

It is an explanatory view showing raw silk.

1...Lens 2...Shutter 3...Photographing element 4...Scanning circuit 5...Signal processing circuit 9...Signal circuit 11...Picture monitor piece 1 concave Key 2 Criminal 4

Claims (1)

[Claims] t The image gI (i! After the readout scan, the dark current and unnecessary fixed signal obtained by the second readout scan without exposure are recorded on a second low-speed recording medium, and the second After storing the video signal obtained by subtracting the dark current and unnecessary fixed signals recorded on the low-speed recording medium in the buffer memory, the buffer memory is read out at high speed to obtain the TV video signal, which is then displayed on the TV screen. Still image shooting system.