JPH02179082A - Solid-state image pickup element driving device - Google Patents

Abstract

PURPOSE:To reduce a residual electric charge by performing the drive of a CCD solid-state image pickup element by setting a mode at a field readout mode, opening all the gates of the CCD solid-state image pickup element, and reading out an unrequired electric charge accumulated in each pixel at the time of sweeping the electric charge. CONSTITUTION:The unrequired electric charge accumulated while a mechanical shutter 2 is closed is transferred, however, all the gates 23 of each pixel of first and second field light receiving parts 21 and 22 are opened since the mode remains while being set as it is at the field readout mode, and all the electric charges are swept. When a frame mode is set after the lapse of first setting time after the shutter 2 is closed, the mode is set at a frame readout mode from the field readout mode, and also, a video signal processing circuit 4 is set at the frame mode. And the shutter 2 is opened only for a decided time synchronizing with a vertical synchronous signal after the lapse of second setting time to sufficiently stabilize the solid-state image pickup element 3 and the circuit 4 for frame recording setting, then, exposure on the element 3 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a solid-state image sensor driving device such as an electronic still camera that captures still images using a solid-state image sensor.

Conventional technology Traditionally, the solid-state image sensor driving device of an electronic still camera reads unnecessary charges accumulated in the solid-state image sensor before actual exposure, and then performs charge conversion and charge accumulation according to the actual exposure. Images are being captured and recorded.

An example of a conventional solid-state image sensor driving device will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of a solid-state image sensor driving device, FIG. 3 is a schematic diagram of a CCD solid-state image sensor, and FIG. 4 is a timing chart during photographing. In FIG. 2, 1 is a lens and 2 is a mechanical shutter, which are driven by a shutter drive circuit 6. 3 is CC
D is a solid-state image sensor and is driven by an image sensor drive circuit 6.

The output is sent to the video signal processing circuit 4. A system control circuit 7 controls the timing of driving the mechanical shutter 2, the timing of driving the CCD solid-state image sensor 3, that is, the timing of charge accumulation and charge transfer, and the operation timing of the video signal processing circuit 4. In FIG. 3, 21 is a first field light receiving section arranged in a matrix pattern corresponding to each picture element of the first field, and 22 is also arranged in a matrix pattern corresponding to each picture element of the second field. This is the second field light receiving section. 23 is the above-mentioned No. 1. A transfer gate is provided for each picture element of the second field light receiving section 21, 22, and is connected to the vertical transfer register 24. 25 is a horizontal transfer register provided at one end of the vertical transfer register 24.

Hereinafter, a conventional solid-state image sensing device driving device will be described with reference to the timing chart shown in FIG.

The CCD solid-state image sensor 3 receives the first field light receiving portion 21 . Charge is accumulated in each picture element of the second field light receiving section 22. Now, when the recording mode is the frame mode, first, in synchronization with the first vertical synchronization signal (FIG. 4a), the transfer gate 23 provided at each pixel of the first field light receiving section 21 is opened, and the data is stored. The signal charges are transferred to the vertical transfer register 24. During this time, the second field light receiving section 22
The charges accumulated in each picture element are not transferred because the transfer gate 23 remains closed. The signal charge transferred to the vertical transfer register 24 is vertically transferred to the horizontal transfer register 25 by one horizontal line every 1H of one horizontal scanning period in synchronization with a horizontal synchronization signal (not shown), and then transferred to the horizontal transfer register 25 by one horizontal line per horizontal scanning period 1H.
are sequentially read out via the . In synchronization with the next vertical synchronization signal, the transfer gate 2 of each picture element of the second field light receiving section 22
3 is opened, and the signal charge accumulated in each picture element is transferred to the vertical transfer gate 24, where it is read out in the same process as in the case of the first field.

When the recording mode is field, the first field light receiving section 21. The charges accumulated in each picture element of the second field light receiving section 22 are synchronized with the vertical synchronization signal, and the charges accumulated in each picture element of the second field light receiving section 22 are transferred to the first field light receiving section 22 in synchronization with the vertical synchronization signal. All transfer gates 23 provided in both picture elements of the second field light receiving section 21 and 22 are opened, and the accumulated signal charges are transferred to the vertical transfer register 24. The signal charges transferred to the vertical transfer register 24 are vertically transferred to the horizontal transfer register 26 by two horizontal lines every 1H of one horizontal scanning period in synchronization with a horizontal synchronization signal (not shown), and
are sequentially read out via the .

When the release switch (not shown) is pressed during shooting,
First, with the mechanical shutter 2 open, photometry is performed using signals from the solid-state image sensor 3 to determine the shutter speed and the like. After completion of photometry, the mechanical shutter 2 is closed and at the same time the frame and field readout modes are set. Then, the unnecessary charges accumulated in the open state are read out in the recording mode set while the device is closed (this is called charge sweep).

After sweeping out the charge for a certain period of time, the mechanical shutter 2 opens for an arbitrarily set period of time in synchronization with the vertical synchronization signal.
The CCD solid-state image sensor 3 is exposed to light.

When the exposure is completed, the signal charge accumulated in the CCD solid-state image sensor 3 is read out in the mode set according to the transfer process described above in synchronization with the vertical synchronization signal, and is transferred to the video signal processing circuit 4 and recorded. be done. This recording period is two vertical synchronization periods in the case of frame recording, and one vertical synchronization period in field recording, and the charge sweep period in each mode also requires at least the same time as each recording period.

Problems to be Solved by the Invention However, in the above configuration, in the case of frame recording, mode C is set to the frame mode before entering the charge sweep period, so the charge sweep period is at least 2
In a solid-state imaging device that requires a vertical phase period and has many afterimages, the charge is not completely swept out and remains as a residual charge. Therefore, the above-mentioned residual charges are added to the signal charges accumulated during the exposure period, which adversely affects the captured image.

In view of the above-mentioned problems, the present invention provides a solid-state imaging device recording method in which the recording mode is set to field mode during the charge sweep-out period to further reduce residual charges.

Means for Solving the Problems In order to solve the above problems, the solid-state image sensor driving device of the present invention includes a solid-state image sensor having a photoelectric conversion means, a charge storage means, and a charge transfer means, and a field-frame of the solid-state image sensor. It has an image sensor drive circuit that can perform charge readout in two ways, and a mechanical shutter. During photographing, after the mechanical shutter is completely closed, the image sensor drive circuit operates the solid-state image sensor for a first set time. After the first set time, the image sensor drive circuit sets the charge readout mode of the solid-state image sensor according to any imaging mode of frame or field, and the mechanical shutter is set in advance. The shutter is opened for a certain period of time, and the exposure to the solid-state image sensor is started.

Effect of the present invention With the above-described configuration, when the mechanical shutter is closed and the charges are swept out, the COD solid-state image sensor is driven in the field readout mode, so all gates of the COD solid-state image sensor are opened, and the first and second gates are opened. The unnecessary charges accumulated in each picture element of the two fields are all read out in a short period of time. As a result, regardless of the desired recording mode for photographing, unnecessary charges are sufficiently swept away, residual charges are also reduced, and flickering is less likely to occur.

EXAMPLE Hereinafter, an electronic still camera according to an example of the present invention will be described with reference to the drawings. FIG. 1 is a timing diagram in one embodiment of the present invention. Figures 1, 2, and 3 below
The operation of this embodiment will be explained using figures.

When the release switch (not shown) is pressed, photometry is performed using the solid-state image sensor with the shutter open. Even if the desired recording mode is frame mode,
Reading continues in the field mode, and the mechanical shutter 1 is completely closed from the open state. While the shutter is closed, unnecessary charges accumulated while the shutter was open are transferred, but since the field readout mode remains set, the first. The transfer gates 23 of each picture element of the second field light receiving section 21, 22 are all opened, and all accumulated charges are discharged. After the mechanical shutter closes and a first set time elapses, in the case of the frame mode, the field readout mode is set to the frame readout mode, and the video signal processing circuit 4 is also set to the frame mode. Then, in synchronization with the vertical synchronization signal after a second set time in order for the solid-state image sensor 3 and the video signal processing circuit 4 to become sufficiently stable with respect to the frame arrangement settings,
The mechanical shutter 2 is opened for a time determined by photometry, etc., and the CCD solid-state image sensor 3 is exposed to light and recorded in the same manner as in the conventional example.

As described above, according to this embodiment, even if the desired recording mode is the frame mode, unnecessary charges are swept out before exposure by transferring the charges in the field mode, so the charges are transferred all at once. More unnecessary charges are transferred in the field mode than in the frame mode, and since residual charges are sufficiently swept away, flickering is less likely to occur.

Further, even if the desired recording mode is the field mode, unnecessary charges are swept out at once before exposure, as in the conventional example, and the present invention does not cause any new problems.

Effects of the Invention As described above, according to the present invention, when sweeping out charges, C
Since the OD solid-state image sensor is driven by field recording readout, unnecessary charges accumulated in each pixel of the first and second field light receiving sections are read out at once, even in a solid-state image sensor with many afterimages. The excellent effect of being able to sufficiently sweep out residual charges and eliminating adverse effects such as flicker can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a timing diagram of a solid-state image sensor driving device according to an embodiment of the present invention, FIG. 2 is a block diagram of the same, FIG. 3 is a schematic diagram of the same solid-state image sensor, and FIG. 4 is a timing diagram of a conventional example. be. 2...Mechanical shutter, 3...CO
D solid-state image sensor, 4...video signal processing circuit, 2
1...First field light receiving section, 22...
・Second field light receiving section, 23...transfer gate, 24...vertical transfer register, 26...
・Horizontal transfer register. Map of low standards

Claims (1)

[Claims] The present invention includes a solid-state image sensor having a photoelectric conversion means, a charge storage means, and a charge transfer means, an image sensor driving circuit capable of performing two types of field-frame charge readout of the solid-state image sensor, and a mechanical shutter. During photographing, after the mechanical shutter is completely closed, the image sensor drive circuit reads charges from the solid-state image sensor in field mode during a first set time, and after the first set time, Depending on the arbitrary shooting mode of frame or field, the image sensor driving circuit sets the charge readout mode of the solid-state image sensor, opens the mechanical shutter for a preset shutter second, and exposes the solid-state image sensor. A solid-state image sensor driving device characterized by: