JPS6239984A - Electronic still camera system - Google Patents

Abstract

PURPOSE:To obtain a picture signal of one frame by exposing after an electric charge in a photodetective part and an exposure part emptied by idly reading a CCD. CONSTITUTION:All electric charge in a photodetecting part and an accumulating part is emptied by idly reading a CCD before an exposure and then the exposure is performed. At that time, at a central time in an exposure time fed by a shutter, within a negligible short period with respect to the exposure period, a signal electric charge is transferred from the photodetective part to the accumulating part. The negligible short period with respect to the exposure period is almost 1/100 of the exposure period. The exposure period is 1/500-1sec according to a purpose of a photographing, preferably 1/200-1/10sec, and especially preferably 1/125-1/15sec for an ordinary purpose. Thereby, a picture signal of one frame can be obtained.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an electronic still camera system using a field transfer type CCD, and more specifically, it is possible to read signal charges of two fields from a field transfer type CCD. This paper relates to an electronic still camera system.

(Prior art) Field transfer type C0D (hereinafter referred to as F'TCCD)
Television cameras using .

In the FTCCD, signal charges formed corresponding to the image formed on the light receiving section are transferred in parallel to the storage section for each field of view, and are successively outputted from the storage section in the scanning order. At this time, the transfer of signal charges from the light receiving section to the storage section is performed alternately with respect to the first field 9 and the second field 9.

(Problem to be Solved by the Invention) Therefore, when such an rTccD is used in a still camera, even if image signal charges for one frame are formed as it is, only one frame's worth of image signal charges are transmitted to the outside. Only signal charges can be extracted.

As a result, the vertical resolution is reduced to half that when used as a television camera.

This is extremely disadvantageous, especially in still cameras where image defects tend to be noticeable.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electronic still camera system that uses FTCCD and does not reduce resolution.

(Means and operations for solving the problem) According to the present invention, this object is achieved as follows. That is, first, before exposure, a blank reading of the CCD is carried out, thereby emptying all charges in the light receiving section and the storage section. Then do the exposure. At this time, at the center of the exposure period given by the shutter, signal charges are transferred from the light receiving section to the storage section within a period so short as to be negligible with respect to the exposure period.

In that case, a period that is negligibly short compared to the exposure period is
1 at approximately 1/100 of the exposure period, and it was found that if the exposure period is below this period, there will be no adverse effect on the image. The transfer of signal charges performed within this period relates to the first field, so to speak, and since exposure continues, signal charges that enter the light receiving section at this time will be formed in the second field. The first one that exists in the storage section after the end of no light.
The signal charges of the fields are read out in accordance with the scanning order, and at the same time, the signal charges of the second field existing in the light receiving section are transferred to the storage section and read out similarly to those of the first field 9 between them.

Therefore, all the signal charges for one frame are effectively used for image formation.

The exposure period is 11,500 to 1 second, preferably 17,200 to 1,710 seconds, and particularly preferably 1/125 to 1/15 seconds for normal purposes, depending on the purpose of photography.

If the exposure period is, for example, 1/100 seconds, the signal charge transfer period during exposure can be 1/10000 seconds.

For an exposure period of 11,500 to 1 second, the signal charge transfer period is 1,150,000 seconds, or 20 microseconds, even at the highest speed, and this time is shorter than the current CCD.
It's not particularly difficult for the technology.

(Example) An embodiment of the present invention will be described below with reference to the drawings.

The figure is a time diagram for explaining the operation of a camera controlled by the method of the present invention. The line shown at the top of the figure represents the operation of the camera shutter. At time to, the shutter opens and closes the period days after this point. Shown below is fCIIi! indicates the control timing of the CCD. Before the point in time, that is, immediately after the shutter button of the camera is operated by the photographer, the CCD is first calibrated. At this time CC
The charge that may remain in the light receiving part and storage part of D is
Everything is ejected and the CCD becomes empty. The period of this readout is about x/3o seconds commuting to school, and the actual exposure starts after this period, but during this period,
In other words, 1/30 second is not so long that the photographer perceives it as an exposure delay. After the blank sequence is completed, the CCD is in an empty state, and this state is schematically shown below the line by indicating the correspondence with the relevant time point with an arrow.

When exposure is started at time to, charges are formed in the CCD light receiving section according to the image. When half of the exposure period tθ has elapsed, approximately the desired charge is formed in the CCD light receiving section. The state of the CCD at this time is also illustrated corresponding to this point. At this time, no signal charge exists in the CCD storage section yet.

Immediately after this, at time ta, the signal charges just formed are transferred from the light receiving section to the storage section. Of course, exposure is also performed during this transfer period, so signal charges newly generated by exposure are dynamically superimposed on the signal charges being transferred, but since the signal transfer period 11 is sufficiently short, , the adverse effect on image quality due to the superimposed signal charges is negligible. CCD during charge transfer
The state of is also as schematically shown in the figure.

This transfer period t1. At the end of the process, the CCD light-receiving section becomes almost empty, and signal charges exist almost exclusively in the CCD storage section. After that, the exposure is continued again for a period of t s /2, so at the end of the exposure period ts, there is a signal charge corresponding to the first field in the CCD storage section, and a signal charge corresponding to the second field in the CCD light receiving section. There is a signal charge that This is also the case as shown in the figure.

Thereafter, the CCD is read out in the usual manner, and an image signal corresponding to one frame is formed.

(Effects of the Invention) As described above, in the electronic still camera system of the present invention, the charge corresponding to the image is F'TCC during the first half of the exposure period.
At the same time as the charge is formed on the light receiving section of D, this charge is transferred to the storage section, and furthermore, in the second half of the exposure period, the charge corresponding to the image is formed on the light receiving section again. Corresponding signals exist in the light receiving section and the storage section, and by reading them out, image signals for 1 frame can be obtained without reducing vertical resolution.

[Brief explanation of the drawing]

The figure is a time diagram illustrating the operation of the system according to the invention. to...Exposure start point, ta...Transfer point, ts
...Exposure period, 11...Transfer period. (2 others) −

Claims (4)

[Claims] (1) In an electronic still camera system consisting of a dark box, an imaging optical system, a shutter, and a solid-state image sensor, the solid-state image sensor consists of a field transfer type CCD, and before exposure, blank reading of the CCD is performed, and then exposure is performed. At this time, at the center of the exposure period given by the shutter, signal charges are transferred from the light receiving section to the storage section within a period that is negligibly short with respect to the exposure period, and after the exposure is completed, the signal charges are transferred from the storage section and the light receiving section in order. An electronic still camera system characterized by reading out signal charges. (2) The method according to claim 1, wherein the period of signal charge transfer from the light receiving section to the storage section during the exposure period is 1/100 or less of the exposure period. (3) The exposure period is 1/500 to 1 second, preferably 1/500 to 1 second.
200 to 1/10 seconds, particularly preferably 1/125 to 1/10 seconds
The method according to claim 2, wherein the time is 15 seconds. (3) The exposure period is 1/500 to 1 second, preferably 1/500 to 1 second.
200 to 1/10 seconds, particularly preferably 1/125 to 1/10 seconds
The method according to claim 2, wherein the time is 15 seconds. (4) The method according to claim 2, wherein the exposure period is 1/100 seconds and the signal transfer period is 1/10000 seconds.