JPS6352583A - Solid-state image pickup device - Google Patents

Abstract

PURPOSE:To attain an optional high speed electronic shutter operation and to improve the sensitivity of a solid-state image pickup by providing a MOS switch whose source is connected to each photoelectric conversion element and controlling a gate potential of the MOS switch so as to control the storage time of the signal charge of a photoelectric conversion element electronically at an optional time. CONSTITUTION:An optical signal through an optical lens 101 is stored in a photoelectric conversion element 201 as a signal charge by allowing a solid-state image pickup element drive circuit 104 to apply normal operation to a solid-state image pickup element 102. Then the charge is transferred sequentially by a vertical transfer stage 202 and a horizontal transfer stage 203. In this case, an undesired charge discharging MOS switch 205 is activated by inputting a gate pulse from a gate pulse input section 207. Then the stored undesired electric charge is discharged from an undesired charge discharge section 206. Moreover, the adverse effect onto the screen is avoided by generating the gate pulse within the horizontal blanking period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a solid-state imaging device that can be used in video cameras and the like.

2. Description of the Related Art In recent years, video tape recorders have adopted functions such as still playback, frame-by-frame forwarding, and slow playback.

However, the NTSC video signal for one field in a video tape recorder is 1/1/2 in a film camera.
Since the signal has a period corresponding to a shutter speed of 60 seconds or 1/30 seconds, if the video tape recorder is kept in a stationary state for a fast-moving subject, a pre-image will occur.

In a video camera using a solid-state imaging device, the photoelectric conversion time, which corresponds to the shutter speed of a film camera, can be electrically controlled to be faster than 1/60 second. (Hereinafter, electrically controlling the photoelectric conversion time of a solid-state imaging device will be abbreviated as an electronic shutter.

) A method of driving a solid-state imaging device for realizing the above-described electronic system J-7 will be described below with reference to the drawings.

The basic structure of the solid-state imaging device is shown in FIG. 4, and consists of a photoelectric conversion section 41, a vertical transfer section 42, a horizontal transfer section 43, and a signal charge detection section 44. The arrow indicates the direction of normal signal charge transfer. In FIG. 4, reference numeral 45 denotes a discharge section provided at one end of the vertical transfer section 42 in the direction opposite to the horizontal transfer section 3 side.

FIG. 5 shows an example of typical drive pulses and outputs of a solid-state imaging device during electronic shutter operation. In Figure 5, (a
) is a composite blanking signal, 0:I) is a transfer pulse (hereinafter abbreviated as charge pulse) that transfers the signal charge of the photoelectric conversion section to the vertical transfer section, and (C) is a transfer pulse that transfers the signal charge of the vertical transfer section to the horizontal transfer section. The transfer pulse (hereinafter abbreviated as vertical transfer pulse) for sequential transfer (hereinafter abbreviated as vertical transfer pulse) (d) is the transfer pulse (hereinafter abbreviated as horizontal transfer pulse) that transfers the signal charge in the horizontal transfer section to the signal charge detection section.Because it is a very high frequency pulse signal, In the figure, the number of pulses is reduced.) (e) is the signal output from the solid-state imaging device.

During the vertical retrace period, the first charge pulse 51 is used to transfer unnecessary signal charges that are not used as a video signal and have been accumulated in the photoelectric conversion section in the period 54 to the vertical transfer section 52 . Next, the vertical transfer section 52 is driven in the direction opposite to the arrow in FIG. Transfer to 45. The discharge section 45 discards all the transferred signal charges.

Thereafter, the charge pulse 52 of the tube 2 transfers the signal charge accumulated in the photoelectric conversion section 41 during the period 63 after the first charge pulse 61 to the vertical transfer section 62 . After this, during the vertical scanning period until the next charge pulse 61, the signal charge for one horizontal line is transferred from the vertical transfer section 42 to the horizontal transfer section 43 by the vertical transfer pulse every horizontal period, as in the case where the electronic shutter is not used. The signals are sequentially transferred, and signals are output in series from the horizontal transfer section 43 through the signal charge detection section 44 in response to horizontal transfer pulses.

As a result, the signal output from the solid-state imaging device during the vertical scanning period is only the signal charge photoelectrically converted during the period 53 in FIG. The period can be from /10 to 1/2 o. In other words, this time corresponds to a shutter speed of 1/600 to 1/1200 seconds of a film camera.

By using the above-mentioned electronic shutter, the sensitivity of the video camera will be reduced by the increase in shutter speed, but even if you freeze, frame advance, slow, etc. during playback on a video tape recorder, the image will not change as compared to the moving image. can be reduced.

Problems to be Solved by the Invention However, in the above configuration, since both the first charge pulse 51 and the second charge pulse 52 exist during the vertical retrace period, the photoelectric conversion period 53 is separated from the vertical retrace period. It cannot be made longer.

That is, in the conventional example, the shutter speed is limited by the vertical retrace period, and there is a drawback that a shutter speed of 1/600 to 1/60 seconds cannot be achieved.

The present invention has focused on the above-mentioned problems, and aims to provide a MOS switch whose source is connected to each photoelectric conversion element, and to arbitrarily change the signal charge accumulation time of the photoelectric conversion element.

Means for Solving the Problems In order to solve the above problems, the present invention provides a solid-state imaging device having two-dimensionally arranged photoelectric conversion elements, including a MOS switch having a source connected to each of the photoelectric conversion elements. A control means is provided for electronically controlling the signal charge accumulation time of the photoelectric conversion element to a desired time by controlling the gate potential of the MOS switch.

Operation The present invention enables arbitrary high-speed electronic shutter operation and improves the sensitivity of the solid-state image sensor with the above configuration.

Embodiments Hereinafter, solid-state imaging devices according to embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an overall block diagram of an embodiment of the present invention. In FIG. 1, 101 is an optical lens, 102 is an interline type COD (charge coupled device), 103 is a signal processing section, and 104 is a solid-state image sensor driving circuit for driving the interline type COD. , 105 is a pulse generation circuit for signal processing.

The operation of the solid-state imaging device using the interline COD configured as described above will be described below with reference to FIGS. 1, 2, and 3.

First, the internal configuration of the solid-state image sensing device (interline type C0D) shown at 102 in FIG. 1 will be briefly explained using FIG. 2. 201 is a photoelectric conversion element (charge storage section), 202 is a vertical transfer section, 203 is a horizontal transfer section, 204 is a signal output section,
205 is a MOS switch for discharging unnecessary charges, 206 is an unnecessary charge discharging section, and 207 is a gate pulse (HG) input section of the MOS switch for discharging unnecessary charges.

The optical signal that has passed through the optical lens 101 in FIG. 1 is transmitted through the solid-state image sensor shown at 102 in FIG. 1 by normally operating the solid-state image sensor drive circuit shown at 104 in FIG.
The signal charges are accumulated in the photoelectric conversion element 201 in FIG. 2, and are sequentially transferred by the vertical transfer stage 202 in FIG. 2 and the horizontal transfer stage 203 in FIG. A TV signal is obtained from the output section shown.

At this time, the unnecessary charge discharge MOS switch shown at 205 in FIG. 2 is operated by inputting the HG1 pulse at the timing shown at 304 in FIG. 3 from the gate pulse input section shown at 207 in FIG. Therefore, 306 in Figure 3
The unnecessary charge accumulated during the period a shown in Fig. 3 is 30 in Fig. 3.
At timing C shown in 6, the unnecessary charge is discharged from the unnecessary charge discharge section 206 in FIG.

Furthermore, by generating the HG1 pulse during the horizontal retrace period as shown at 308 in FIG. 3, it is possible to avoid adverse effects on the screen.

Furthermore, the signal charges accumulated during the period b shown at 306 in FIG.
are read out and sequentially transferred to the vertical transfer stage shown in FIG. 202,
Further, the signal is sequentially transferred by the horizontal transfer stage shown at 203 in FIG. 2, and obtained as a high-speed TV signal from the output section shown at 204 in FIG.

Thereafter, the TV signal is subjected to signal processing in a signal processing unit shown at 103 in FIG. 1 to obtain a high-speed NTSC signal.

By varying the HG1 pulse shown at 304 in FIG. 3 to an arbitrary timing, the accumulation time of the signal charge obtained as a TV signal can be controlled to an arbitrary time, making it easy to perform high-speed imaging with high sensitivity. It will be held on.

In addition, by inputting the HG pulse at the timing of HG2 shown at 305 in FIG. 3, unnecessary charges generated by the photoelectric conversion element are not accumulated during the period a shown at 306 in FIG. The signal charges accumulated in the photoelectric conversion element during the period b shown in FIG. 3 306 are discharged from the unnecessary charge discharge section shown in FIG. A similar effect can be obtained by using the reading means shown in 202 in the vertical transfer stage.

Effects of the Invention As described above, according to the present invention, it is possible to obtain an excellent effect of increasing the sensitivity of a high-speed solid-state imaging device.

[Brief explanation of the drawing]

Fig. 1 is an overall block diagram of an embodiment of the present invention, Fig. 2 is a configuration diagram of a solid-state imaging device of this embodiment, Fig. 3 is a timing diagram of an embodiment of the invention, and Fig. 4 is a conventional solid-state imaging device. FIG. 5, which is a block diagram of the inside of the device, is a timing chart for explaining means for operating a conventional solid-state image pickup device using an electronic shutter. 101... Optical lens, 102... Solid-state image sensor (interline type CCD), 103...
... Signal processing unit, 104 ... Solid-state image sensor drive circuit, 105 ... Pulse generation circuit, 201
...Photoelectric conversion element, 202...Vertical transfer section, 203...Horizontal transfer section, 204...
...Output section, 205...MOS for discharging unnecessary charge
Switch, 208...Unnecessary charge discharge section, 207
...HG wide pulse force section. Name of agent: Patent attorney Toshio Nakao and 1 other person 41
- Charging converter section 42 - - 1 bit r & car 5 transmission 1 voice 43 - Decorating the rotation of the tree 44 = - (ty electric FT detection sister 4 - Ejection part Fig. 4

Claims (3)

[Claims] (1) A solid-state imaging device having photoelectric conversion elements arranged two-dimensionally, wherein a MOS switch is provided with a source connected to each of the photoelectric conversion elements, and the gate potential of the MOS switch is controlled. A solid-state imaging device characterized by having a control means for electronically controlling the accumulation time of signal charges of a photoelectric conversion element to an arbitrary time. (2) The solid-state imaging device according to claim 1, characterized in that the gate potential of the MOS switch is changed within a horizontal retrace period. (3) The MOS switch is cut off during a period in which signal charges are to be accumulated in the photoelectric conversion element, and is made conductive during periods other than the above.
The solid-state imaging device described in .