JPS5951674A - Electrophotographic camera - Google Patents

Abstract

PURPOSE:To attain excellent still picture, by opening a shutter in synchronizing with a vertical synchronizing signal so as to obtain a image pickup signal of a correct still picture independently of a type of the image pickup element to be employed. CONSTITUTION:A two-dimensional image pickup element 103 is driven in synchronizing with a television synchronizing signal generated from a synchronizing signal generator 107 and an object image is formed on the pickup element 103 via a lens system 101. A shutter device 201 is arranged between the lens 101 and the pickup element 103 and the shutter device 210 is opened with a command of the release switch 203. In recording a still picture, the shutter device 210 is opened in synchronizing with a vertical synchronizing signal of a television synchronizing signal and the reading is stopped at the same time and the stop state is held until the next vertical synchronizing signal. Further, the reading and writing of signal is attained in synchronizing with the vertical synchronizing signal.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic camera that takes still images using a two-dimensional photoelectric conversion element.

Conventional configuration and its problems In conventional photographic devices, the shutter opening time (generally referred to as shutter speed) is controlled in order to record the instantaneous state of the subject and adjust the exposure amount. has been done. The timing of opening the shutter is uniquely controlled only by human control, and there is no time limit.

In addition, electronic devices for recording still images have the function of converting an optical image of a subject into an electrical signal using an image pickup tube or MOS-CCD solid-state imaging plate, and recording this electrical signal on a storage medium such as a magnetic disk or magnetic bubble memory. In a photographic camera, a shutter provides a similar function as in the case of the above-mentioned photographic device. However, in some electrophotographic cameras, depending on the imaging device used, if the shutter opening timing is arbitrarily controlled, the following inconvenience may occur.

FIG. 1 is a basic configuration diagram of a conventional electrophotographic camera. A subject (not shown) is imaged by the lens 101 on the imaging surface of the image sensor 103, but normally the shutter 10
2 blocks the incident light. The image sensor 103 is driven by a drive circuit 106 for charge accumulation, signal reading, etc. in synchronization with a synchronization signal generated by a synchronization signal generator 107.

The output signal from this image sensor 103 is transmitted to the signal processing circuit 10.
4, the signal is processed into a signal format suitable for recording, and then guided to the recording device 105.

Note that in the normal state (when not photographing a subject image), incident light from the subject is blocked by the shutter 1o2, but dark charges are generated, so the image sensor 103 is driven normally to remove this charge. The action is taking place,
A signal corresponding to this dark charge is also guided to the recording device 105, but this signal is not recorded.

When capturing an image of a subject, when the release switch 108 is pressed, the shutter 102 is opened for a time Ts set by the shutter speed setting device 109, and the subject image is incident on the image sensor 103. Note that this shutter may be one in which the transition from the closed state to the open state is performed by mechanical force or by an electric signal. Then, the shutter state detection circuit 110 generates a shutter opening pulse as shown in FIG. Here, a high level represents an open state, and a low level represents a closed state. This pulse b is guided to the drive circuit 106 so that the charge reading operation of the image sensor 103 is stopped and the charge accumulation operation is performed during this period. However, in the trench where the next vertical synchronizing signal Vs is generated as shown in FIG.
When using an element in which it is difficult to change the operating conditions of step 3, for example, an MO3 type solid-state image sensor, which has a configuration in which charges are sequentially read from light receiving elements arranged within the image sensor, FIGS. 2C and 2C' are waveform diagrams showing the operating states of the parsodial field and even field elements, respectively. A high level indicates a reading operation, and a low level indicates an accumulation operation, and the shutter release pulse bKl, as shown by the dotted line of the waveform C', shows the solid line when the normal state should be a reading operation. As shown in , the reading is stopped as an accumulation operation.

Therefore, as the output signal of the image sensor 103, the second
In the normal state, the image sensor 103 outputs a dark current Id due to dark charges, as shown in the output of the element for the parsimonious field shown in Figure d and the output of the element for the even field shown in Figure 2 d'. . After the shutter is opened, the dark current components Id and Id' (indicated by dotted lines in the waveform diagram of d and d') are supplied with a signal current 1s1 corresponding to the accumulated charge caused by the incident light.
and I61 are added together, and the current is output. During the period from time t1 when the shutter 102 is opened to time t2 when the next vertical synchronization signal Vs is generated, charge accumulation by incident light and charge readout are performed simultaneously in the image sensor 103. Each light-receiving element constituting a unit pixel inside the unit outputs a signal current corresponding to the charge accumulated before the reading operation, and the waveform for the period from time t1 to t2 in Fig. 2d is shown. As shown, a signal output proportional to the passage of time after the camera is opened is obtained (in this explanation, the subject is assumed to be uniform throughout the screen). Then, the next time this light receiving element 103 performs a reading operation, it outputs a signal current corresponding to the charge accumulated after the previous reading operation, and the waveform shown from time t4 to t5 in FIG. The signal will be as follows.

On the other hand, the image sensor 1 is used for the even field during the period t1 to t3 when the shutter 102 is open.
Since the storage operation state was uniform throughout the entire screen of 03, the output signal during the reading operation is a uniform signal Is over the entire screen, such as the waveform shown from time t5 to t6 in Fig. 2 d'.
' becomes.

The signals shown at d and d' are added together and guided to the signal processing circuit 104, where the dark current component is calculated based on the output signal from the light-receiving element that corresponds to the optically black area provided in the image sensor 103. After being removed and subjected to other signal processing, the signal is guided to the recording device 105.

The shutter opening pulse shown in FIG. A pulse (FIG. 2e) that goes high for two vertical scanning periods from the signal Vs is generated and guided to the recording device 105 as a recording control signal, and the signal current being guided to the recording device 105 at that time is The process of recording a series of still images is completed.

It goes without saying that a synchronization signal is also sent to the signal processing circuit 104 and the recording device 106 from the synchronization signal generator to maintain synchronization of the entire system.

However, in an electrophotographic camera with such a configuration, the recorded image signals are different between odd and even fields, as shown in Figure 2 f, making it difficult to accurately record the subject image. It doesn't matter. For example, when this recorded signal is reproduced on a television monitor, flicker occurs due to differences in the signals, and when output as a hard copy using a printer, shading occurs between lines.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of conventional electrophotographic cameras as described above, and makes it possible to accurately record still images in which odd field signals and even field signals match, regardless of the type of image sensor used. The purpose of the present invention is to provide an electronic photographic camera capable of realizing the following.

Structure of the Invention In the present invention, first, a two-dimensional image sensor is driven in synchronization with a television synchronization signal generated by a synchronization signal generator, and a subject image is formed on this image sensor via a lens system. image. A shutter device is disposed between the lens and the image sensor, and a release switch is provided for instructing the shutter device to open. When recording a still image, the shutter device is opened in synchronization with the vertical synchronization signal of the television synchronization signals, and at the same time the reading operation of the image sensor is stopped. After the shutter closes, it is held for at least the period of the next vertical synchronization signal 1. The present invention is characterized in that signals are read from the image sensor and recorded and written to the recording device in synchronization with this vertical synchronization signal.

Description of examples An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a basic configuration diagram of an embodiment of the present invention, in which the same parts as in the prior art are denoted by the same reference numerals as in FIG. 1. Since the operation of this device in its normal state (when not photographing or recording a subject image) is the same as that of the conventional device described above, a description of this normal state will be omitted. Note that the shutter 201 used in this device is different from the conventional shutter 102 in that it is operated from the closed state to the open state by an electric signal, but its function in the closed state is the same as that of the conventional shutter. .

When photographing a subject image, when the release switch 203 is pressed, a pulse as shown in FIG. 4 is generated. Is this Nokurusu b a shutter? IttI wander + synchronization signal generation η=i:;1 guided by signal generator 204
It is used for control together with the vertical synchronizing signal Vs as shown in FIG. A shutter control signal as shown in FIG. 4C, which is at a high level for a set time period Ts, is generated. This shutter control signal C controls the shutter 201 to open. However, it is assumed that the shutter 201 is controlled so that the shutter 201 is opened only during the high level period of this shutter control signal C, and the shutter 201 is closed during the low level period.

When the shutter 201 is opened, a subject image is incident on the crab image sensor 103. The shutter control signal as shown in FIG.
5, the shutter control signal C is used together with the vertical synchronization signal Vs and rises from a low level to a high level at time t7 at the same time as the rise of the shutter control signal C.
Vertical synchronization signal V after changes from high level to low level
In synchronization with s , a read stop signal as shown in the fourth diagram that falls from high level to low level at time t 2 (reading stops when at high level) is generated.

This read stop signal is guided to the drive circuit 206,
Reading out the charges from the image sensor 103 is stopped to maintain the accumulation state. In other words, FIG.
As shown in the waveform diagram of d/ (here, a high level indicates the reading operation and a low level indicates the state of storage operation), the read stop signal is activated as shown by the dotted line in the waveform diagram of d/. In the normal state, when the reading operation should be started, the reading is stopped and the storage operation is started as shown by the solid line.

Therefore, the shutter 201 is opened and the image sensor 1
The subject image incident on 03 is uniformly accumulated over the entire screen in both the odd field element and the even field element, and the fourth image obtained by the reading operation immediately after opening the shutter 201. The output of the element for the odd field shown in the signal number form from time t8 to t9 of the waveform shown in FIG.

The output of the even field element shown in the signal waveforms up to is a signal current T s 2 depending on the amount of incident light.

I 8'2 will be the same. At this time, the dark current components included in this signal are Id and I'd as shown by dotted lines.

The signals shown in Figures f, e and e' in Figure 4 are added together and guided to the signal processing circuit 104, where the dark current component is removed in the same manner as in the prior art, and after being subjected to other signal processing, the signals are sent to the recording device 106. be guided. On the other hand, the shutter control signal shown in FIG. Then, a recording control signal as shown in FIG. 4 is generated which rises from a low level to a high level at time t8 and remains at a high level for two vertical scanning periods up to time t1.

This recording control signal is guided to the recording device 105, and the recording device 105 is controlled to record the imaging signal that is being guided from the signal processing circuit 104 at that time, and recording of the still image is completed. Note that the signal processing circuit 104 and the recording device 10
5 is also supplied with a synchronizing signal from the synchronizing signal generator 107, and the synchronization of the entire system is maintained as in the conventional case.

According to the above configuration, the image signal recorded in the recording device 105 accurately represents the input image in both the odd field signal and the even field signal, as shown in the figure 4, and produces a correct still image. It will be possible to record. Therefore, when this recorded signal is reproduced to the television motor, a good still image without flicker can be reproduced, and even when a hard copy is made, no shading occurs between lines.

Effects of the Invention As described above, according to the present invention, by opening the shutter in synchronization with the vertical synchronization signal, correct stopping can be achieved in both odd and even fields, regardless of the type of image sensor used. It is possible to obtain an imaging signal of an image, and to obtain a good still image that is accurate and does not cause flicker or line-to-line shading during reproduction.

[Brief explanation of the drawing]

FIG. 1 is a basic configuration diagram of an electrophotographic camera as an example of the conventional technology, FIG. 2 is a signal waveform diagram of each part thereof, FIG. 3 is a basic configuration diagram of an electrophotographic camera according to an embodiment of the present invention, and FIG. 4 is a signal waveform diagram of each part. 101...Lens, 103...Image sensor, 1o 201...Shutter, 104...
... Signal processing circuit, 105 ... Recording device,
107... Synchronization signal generator, 111...
・Recording control signal generator, 201... Nyatter, 2o2... Shutter speed setting device, 20
3...Release switch, 2o4...
Shutter control signal generator, 206... Read stop signal generator, 206... Drive circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
0 1 01 Paper afternoon

Claims (1)

[Claims] A television synchronization signal generator, a two-dimensional photoelectric conversion element driven in synchronization with the television synchronization signal generated by the television synchronization signal generator, and a lens for forming a subject image on the photoelectric conversion element. a shutter device disposed between the photoelectric conversion element and the lens; a release switch for instructing opening of the shutter device; and a vertical scanning system in which there is at least a period in which the shutter device is kept open. means for stopping signal reading of the photoelectric conversion element during the period; and means for stopping the signal reading of the photoelectric conversion element in the first half; and a means for stopping the reading of the signal from the photoelectric conversion element in the preceding period; An electronic photographic camera comprising: means for operating the camera from a closed state to an open state.