JPS63316576A - Solid-state image pickup element and its driving system - Google Patents

Abstract

PURPOSE:To simultaneously satisfy the expansion of an aperture rate and the expansion of a dynamic range which are opposed to each other by reducing the occupied area of a vertical transfer part in an image pickup part, increasing the aperture rate and rapidly transferring charge to an integrator. CONSTITUTION:An image pickup part 12 sends charge obtained from a photoelectric conversion part 10 to the vertical transfer part 11 by dividing it into plural times based on pulses phiA. The horizontal width of the transfer part 11 is sufficiently narrower than that of the conversion part 10 and its aperture rate is large. An integrator 13 in an integration part 16 temporarily stores charge obtained from each vertical transfer part 11, sweeps the charge rapidly at a 4-phase pulse phiB, and controls a transfer gate 18 at a pulse phiT to transfer and sweep charge to/from each integrator 13. The swept charge is outputted from a terminal 18 as a video signal at pulses phiC, phiH through a register 15 and a horizontal transfer part 14. The sensitivity is improved by increasing the aperture rate of the image pickup element and the dynamic range is sharply expanded by rapidly transferring the small quantity of charge in each time from the vertical transfer part 11 having an area smaller than that of the conversion part 10. The sensitivity can be changed by properly thinning the sweeping charge of the photoelectric conversion part 10.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a solid-state image sensor such as a COD (charge-coupled device) and its driving method, and in particular to improving the dynamic range and aperture ratio of the solid-state image sensor. , the sensitivity can be varied.

(Prior Art) Solid-state image sensors such as COD have been used as photoelectric conversion elements in various television cameras, electronic still cameras, etc., and this type of solid-state image sensor converts the imaging light irradiated onto the imager section into photoelectric converters. The signal charges obtained by conversion are converted into two-phase or four-phase
A video signal corresponding to the imaging light is output by sequentially transferring and reading the signals using phase clock pulses.

For example, as shown in FIG. 6, an interline CCD is composed of an imager section 3 consisting of a photoelectric conversion section 1 and vertical transfer sections 2 arranged alternately, and a horizontal transfer section 4. The signal charge obtained in section 1 is transferred to drive circuit 5.
It is designed to be swept out via the vertical transfer section 2 and the horizontal transfer section 4 by a clock pulse CP supplied from the vertical transfer section 2 and the horizontal transfer section 4.

(Problems to be Solved by the Invention) In the interline type COD as described above, the dynamic range of the COD is limited by the amount of charge transferred by the vertical transfer section 2.

Furthermore, the dynamic range can be increased by increasing the amount of charge transferred by the vertical transfer section 2, but in that case, the area occupied by the vertical transfer section 2 in the imager section 3 increases and the aperture ratio decreases. Sensitivity deteriorates due to storage.

(Means for solving the problems) The present invention has been made in view of the above-mentioned circumstances,
It is an object of the present invention to provide a solid-state imaging device and a driving method thereof that can satisfy the contradictory conditions of expanding the dynamic range and expanding the aperture ratio, and can also vary the sensitivity.

To achieve this object, the present invention provides a photoelectric conversion section 10 that photoelectrically converts imaging light corresponding to each pixel, and a vertical transfer section that transfers charges from these photoelectric conversion sections 10, as shown in FIG. 11, and each photoelectric conversion unit 10 transferred from the imager unit 12.
an integrator 13 that temporarily accumulates the charge from the integrator 1;
The imager section 12 includes a vertical register 15 and a horizontal transfer section 14 for outputting charges swept out from the imager section 12 as a video signal, and the area occupied by the vertical transfer section 11 in the imager section 12 is compared with the area occupied by the photoelectric conversion section 1o. At the same time, the storage capacity of each integrator 13 is made larger than the amount of charge obtained in each photoelectric conversion unit 10 by one exposure, and the charges obtained in each photoelectric conversion unit 10 are A solid-state image pickup device characterized in that the image is transferred to the vertical transfer section 11 in batches and transferred from the vertical transfer section 11 to each integrator 13 at high speed in time for the transfer from the horizontal transfer section 14. , and an imager section 12 having a photoelectric conversion section 10 that photoelectrically converts imaging light corresponding to each pixel, and a vertical transfer section 11 that transfers charges from these photoelectric conversion sections 10, and transfer from this imager section 12. Each photoelectric conversion unit 10
an integrator 13 that temporarily accumulates the charge from the integrator 1;
A vertical register 5 and a horizontal transfer section 14 are provided for outputting charges swept out from the imager section 3 as a video signal, and the area occupied by the vertical transfer section 11 in the imager section 12 is compared with the area occupied by the photoelectric conversion section 10. At the same time, the storage capacity of each integrator 13 is made larger than the amount of charge obtained in each photoelectric conversion unit 10 by one exposure, and the charges obtained in each photoelectric conversion unit 10 are This is a driving method for a solid-state image sensor, in which the image is swept to the vertical transfer section 11 in batches and transferred at high speed to the integrator 13 of the vertical transfer section 11i in time for the sweep from the horizontal transfer section 14. , provides a driving method for a solid-state image pickup device characterized in that the sensitivity can be varied by arbitrarily thinning out the charges swept out in multiple steps from each of the photoelectric conversion units 10.

(Function) In the solid-state image sensor configured as described above, by reducing the area occupied by the vertical transfer section 11 in the imager section 12, the aperture ratio of this type of solid-state image sensor can be increased (and the sensitivity can be improved). can be achieved.

Furthermore, by providing an integrator 13 and transferring the charge obtained in the photoelectric conversion section 10 from the vertical transfer section 11 to the integrator 13 at high speed, the amount of charge transferred per unit time of the vertical transfer section 11 can be reduced. can be significantly increased.

As a result, the charges obtained in the photoelectric conversion section 10 are divided into multiple times and swept out to the vertical transfer section 11, and the swept out charges are transferred at high speed, thereby greatly increasing the dynamic range of this type of solid-state image sensor. Can be expanded.

Furthermore, the charges swept out from the photoelectric conversion section 10 are
By appropriately thinning out the pixels as shown in FIG. 2(B) or (C), the sensitivity of this type of solid-state imaging device can be varied.

(Example) Hereinafter, a first preferred example of the solid-state image sensor according to the present invention will be described.
This will be explained in detail with reference to FIGS.

FIG. 1 shows an application of the present invention to a frame interline type COD, which includes an imager section 12, an integrator section 16, a storage section 17 consisting of a vertical register 15, and a horizontal transfer section 14. It is configured.

The imager section 12 includes a plurality of photoelectric conversion sections 10 arranged in the vertical direction corresponding to each pixel, and each photoelectric conversion section 10.
The vertical transfer section 11 provided between the photoelectric converters 10 and The data is swept out and transferred to the vertical transfer unit 11 in batches.

Further, the horizontal width dimension of the vertical transfer section 11 is formed narrower than the width dimension of the photoelectric conversion section 10, so that the area occupied by the vertical transfer section 11 in the imager section 12 is smaller than that of the photoelectric conversion section 10. It is sufficiently smaller than the occupied area.

Therefore, the aperture ratio in this COD is extremely large compared to the conventional one.

The integrator section 16 is configured to include a plurality of integrators 13 corresponding to each of the photoelectric conversion sections 10, and these integrators 13 temporarily accumulate charges transferred from each of the vertical transfer sections 11. Thereafter, the liquid is swept out at high speed using a four-phase clock pulse φ8.

Note that the transfer or sweeping out of charges to each integrator 13 is controlled by a transfer gate 18 controlled by a clock pulse φ.

The charge swept out from each integrator 13 of the integrator section 16 is a four-phase clock pulse φ. .

The signal is output from an output terminal 18 as a video signal via a vertical register 15 and a horizontal transfer section 14, each driven by φ8.

In the COD configured as described above, the charges obtained by photoelectrically converting the imaging light in each photoelectric conversion unit 10 are divided into multiple times by a predetermined sweeping method as shown in FIG. It is swept out to the transfer section 11.

Note that this sweeping method is not only possible by mixing the upper and lower pixel forces and then sweeping, but also by sweeping all pixels as is, as described later, and by changing the combination of the upper and lower pixels, increment sweeping is also possible. be.

Furthermore, assuming that the sweep speed from the horizontal transfer section 14 is 1/60 second, the vertical transfer section 11 performs transfer at a high speed of about 100 times (60 kHz).

As a result, the area of this vertical transfer section 11 becomes smaller than that of the photoelectric conversion section 1.
Even if the area is smaller than the area of Since all the charges can be sufficiently transferred and the amount of charges transferred in the - times is reduced, the vertical transfer section 11 is controlled by the two-phase clock pulse φ as described above. It can be driven by.

While charges are being transferred from the vertical transfer section 11, the transfer gate 18 is opened and each integrator 13 is placed in the hold mode, and the transferred charges are temporarily stored in each integrator 13. be done.

This integrator section 16 continues this for 1/60 seconds (one field period), and after the charge accumulation for one frame obtained in the photoelectric conversion section 10 is completed, the transfer gate The charges accumulated through 18 are transferred to the clock pulse φ
The data is swept out in an interlaced manner one field at a time at a fast transfer rate and transferred to each vertical register 15 of the storage section 17.

Then, the transferred charge is generated by the above-mentioned O-sock pulse φ. ,
The data is transferred to the vertical register 15 and the horizontal transfer IIJ 14 at φ, and output one field at a time from the output terminal 19.

As described above, in the COD according to this embodiment, since the area occupied by the vertical transfer section 11 can be made sufficiently small, the aperture ratio of this COD can be increased.

Furthermore, by increasing the transfer speed from the vertical transfer section 11 to each integrator 13, the amount of charge transferred by the vertical transfer section 11 can be increased, so the dynamic range of this COD can also be expanded. .

On the other hand, while charges are being transferred from the vertical transfer section 11, each of the integrators 13 is placed in a hold mode, and the transfer gate 18 is opened and closed at a predetermined timing, so that the transfer gate 18 is closed. By discarding the charges transferred in between through an overflow train (not shown), the charges obtained by one exposure can be thinned out, and thereby the sensitivity of this COD can be arbitrarily varied.

For example, see Figure 2 (B) for this thinning method.
Among the charges swept out from the photoelectric conversion unit 10, as shown in FIG. Just make sure to thin it out evenly.

By the way, in the above-described embodiment, the charges of each photoelectric conversion unit 10 are mixed and then swept out, but as shown in FIG. 3, the charges may be swept out without being mixed.

In this case, the integrator in the integrator section 16 is
It is divided into a part 130 that stores charges for odd fields and a part 13e that stores charges for even fields, and each photoelectric transformer is connected to these integrators 130 and 138 by transfer 1 gates 18o and 18e, which are driven and controlled by clock pulse φT1. J1! In addition, vertical registers 15o, 15e and horizontal transfer unit 140 are configured to selectively transfer charges from section 10, and further, corresponding to each integrator 13o, 13e, vertical registers 15o, 15e and horizontal transfer section 140
14e are each made into two channels, and the charge transfer path is controlled by transfer gates 20 and 21 which are driven and controlled by clock pulses φV and φT2, respectively.

Next, another embodiment according to the present invention will be described.

As shown in FIG. 4, the frame incline type COD according to this embodiment includes an imager section 12, an integrator 16, a storage section 17, and a horizontal transfer section 14 similar to those of the previous embodiment, and the integrator 16 A horizontal register 23 is provided between the storage unit 17 and the storage unit 17.

Charges swept out from the horizontal transfer section 14 are transferred to the horizontal register 23 via a switch 24.

As a result, the COD according to this embodiment circulates the charge obtained by one exposure a plurality of times at a predetermined period, and outputs the same charge from the output terminal 19 for each cycle.

Therefore, for example, one exposure time is one field period (1
/60 seconds), by setting the cycle period to 1/60 seconds as described above, it is possible to obtain a video signal for each field, and the exposure time is especially short when photographing subjects with low illumination. Since the length can be increased, the sensitivity can be significantly improved.

In addition, regardless of the exposure time, the charge obtained by one exposure can be output multiple times, making it easy to obtain video signals for frame still playback or strobe playback, especially for fast-moving subjects. When performing frame still playback, it is possible to obtain a reproduced image that is free from blur and clearer than field still playback.

Further, according to the present invention, as described above, the aperture ratio of the imager section 12 can be increased to improve the sensitivity, so even when the exposure time is extremely short, sufficient charge can be obtained. , this makes the COD according to this example
By using this, the image quality of frame still playback can be further improved.

Also, since the dynamic range of this COD is large,
Even when photographing a bright subject with a long exposure time, it is possible to prevent smearing and blooming and take clear photographs.

Note that the transfer and sweeping of charges to the horizontal register 23 in this COD is controlled by transfer gates 25 and 26 which are driven and controlled by clock pulses φT and φ■.

Further, in this embodiment, the charges of each photoelectric conversion unit 10 are mixed and then swept out, but the arrangement may be such that the charges are swept out without being mixed, as shown in FIG.

In this case, integrators 13o, 13e, vertical register 15
o, i 5e , horizontal transfer units 14o, 14e and horizontal registers 230.23e! are configured into two channels each, and clock pulses φ'rl+φT2 . φv9+
φVL1. φVL2. Transfer gates 180°18e, 27, 28, 29 each driven and controlled by φ■4
．． The charge transfer path may be controlled in 30.31.

(Effects of the Invention) As is clear from the above description, according to the first invention, the aperture ratio of the imager section can be increased and the dynamic range can be expanded.

Furthermore, since the amount of charge transferred per transfer by the vertical transfer section is reduced, this vertical transfer section can be driven with two-phase clocks.

Furthermore, according to the second invention, the sensitivity of the solid-state image sensor can be varied by appropriately thinning out the charges swept out from the photoelectric conversion section.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing an embodiment of the solid-state image sensor according to the present invention, FIG. 2 is a diagram schematically showing charge sweeping, and FIG. 3 is a diagram schematically showing another embodiment. , FIG. 4 is a diagram schematically showing another embodiment, FIG. 5 is a diagram schematically showing still another embodiment, and FIG. 6 is a diagram schematically showing a conventional example. 10... Photoelectric conversion section, 11... Vertical transfer section, 12.
...imager section, 13...integrator, 14...horizontal transfer section, 15...vertical register. Figure 4 5y: J

Claims (2)

[Claims] (1) An imager section that has a photoelectric conversion section that photoelectrically converts imaging light corresponding to each pixel and a vertical transfer section that transfers charges from the photoelectric conversion section to this, and each photoelectric conversion that is transferred from this imager section. It is equipped with an integrator for temporarily accumulating the charge from the integrator, a vertical register and a horizontal transfer section for outputting the charge swept out from the integrator as a video signal, and the area occupied by the vertical transfer section in the imager section is Each photoelectric conversion section is formed sufficiently small compared to the area occupied by the conversion section, and the storage capacity of each of the integrators is made larger than the amount of charge obtained in each photoelectric conversion section by one exposure. The charge obtained in is swept out to the vertical transfer section in multiple steps, and is also transferred at high speed from the vertical transfer section to each integrator in time for the charge to be swept out from the horizontal transfer section. solid-state image sensor. (2) An imager section having a photoelectric conversion section that photoelectrically converts imaging light corresponding to each pixel and a vertical transfer section that transfers charges from the photoelectric conversion section to the photoelectric conversion section, and each photoelectric conversion section transferred from this imager section. It is equipped with an integrator for temporarily accumulating the charge from the integrator, a vertical register and a horizontal transfer section for outputting the charge swept out from the integrator as a video signal, and the area occupied by the vertical transfer section in the imager section is Each photoelectric conversion section is formed sufficiently small compared to the area occupied by the conversion section, and the storage capacity of each of the integrators is made larger than the amount of charge obtained in each photoelectric conversion section by one exposure. The solid-state image sensing device is configured to sweep out the charge obtained in the step to the vertical transfer section in a plurality of times and transfer it from the vertical transfer section to each integrator at high speed in time for the charge to be swept out from the horizontal transfer section. What is claimed is: 1. A driving method for a solid-state image sensor, characterized in that the sensitivity can be varied by arbitrarily thinning out charges swept out in multiple steps from each of the photoelectric conversion sections.