JPH02174473A - Solid-state image pickup element - Google Patents

Abstract

PURPOSE:To suppress the deterioration in the after-image characteristic at low illuminance pickup by arranging a readout gate to a part as close as possible in the center of a side on which a photo sensor and a vertical shift register are located adjacently. CONSTITUTION:A readout gate 5 from a photo sensor 1 to a vertical transfer section 2 is arranged to the center of the side where the photo sensor 1 and the vertical transfer section 2 are adjacent to each other to short the longest distance from the readout gate 5 to the photo sensor 1 as short as possible. Thus, the incomplete transfer to the vertical transfer section 2 due to a stall is hardly occurred and the deterioration in the after-image characteristic is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a solid-state image sensor, and more particularly to the structure of a readout gate that transfers signal charges from a photosensor to a vertical transfer section.

Conventional technologySolid-state image sensors are lighter, more durable, and have lower afterimages than image pickup tubes.
It is excellent in terms of burn-in, comet tail, etc., and is expected to replace the currently used shooting tubes.

An example of a conventional interline type solid-state image sensor, which is an example of this type of solid-state image sensor, is shown in FIG. 3, and a plan view of the cell section is shown in FIG. 4.
1) Readout signal charge from 1) 2nd which also serves as 15
An example of the clock pulse applied to the gate 18 of the fifth
As shown in the figure.

From FIGS. 3 and 4, the light incident on the photosensor 11 forms a signal charge according to the amount of light, and is transferred via the readout gate 15 within the vertical blanking period by the readout pulse vH of FIG. The signal is transferred to the vertical transfer section 12 composed of a first gate 17 and a second gate 18. The entire charge pattern of the vertical transfer section 12 is transferred in parallel row by row to the horizontal transfer section 13 for each horizontal scanning line, and is sequentially outputted from the signal output section 14 as a video signal.

Problems to be Solved by the Invention However, in the solid-state device 1 as described above, the readout gate 15 for reading signals from the photosensor 11 to the vertical transfer section 12 is connected to the photosensor 11 as shown in FIG. If the peak value V of the read pulse shown in FIG. 5 is low, if the waveform is dulled by the load, or if the pulse width Vw is short, In this case, the sensor 1 is far away from the readout gate 15 shown in FIG.
The signal charges excited during MW 1 stall and become incompletely transferred to the vertical transfer section 2 within the readout period, resulting in an afterimage characteristic due to some of the signal charges being left behind in the photosensor 11. There was a drawback that the image quality was poor, especially the afterimage characteristics at low illuminance.

The present invention has been made in view of the above-mentioned conventional situation,
Therefore, an object of the present invention is to provide a novel solid-state image sensor that can overcome the above-mentioned drawbacks inherent in the conventional technology.

Differences between the invention and the prior art In contrast to the conventional solid-state image sensing device described above, the present invention has the advantage that the readout gate 5 for reading the signal charge of the vertical transfer section 2 from the photosensor 1 is connected to the adjacent side of the photosensor 1 and the vertical transfer section 2. The difference is that the readout gate 5 is arranged at or near the center of the photo sensor 1, and the longest distance between the readout gate 5 and the photosensor 1 is made as short as possible.

Means for Solving the Problems In order to achieve the above object, the solid-state imaging device according to the present invention includes a plurality of photosensors 1 that accumulate signal charges according to the amount of incident light, and a signal charge that is read out from the photosensors 1. The vertical transfer section 2 is composed of a first gate 7 and a second gate 8 that transfer signal charges, and the vertical transfer section 2 is located at or near the center of the adjacent side of the photosensor 1 and the vertical transfer section 2. Second
a readout gate 5 which reads signal charges from the photosensor l to the vertical transfer section 2 during the vertical blanking period; The structure includes a horizontal transfer section 3 that sequentially transfers signal charges to a signal output section and a signal output section 4, and the readout gate 5 is connected to a photo sensor l.
Embodiments 6. Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a plan structural diagram of a cell section showing a first embodiment of the present invention, which is adapted to the plan structural diagram of the cell section of FIG. 4, which is an example of the prior art.

Referring to FIG. 1, the first embodiment of the present invention includes a plurality of photosensors 1 that accumulate signal charges according to the amount of incident light, and a plurality of photosensors 1 that transfer signal charges read out from the photosensors 1. A vertical transfer section 2 consisting of a first gate 7 and a second gate 8 is located at the center of the adjacent side of the photosensor 1 and the vertical transfer section 2, and is located at the center of the adjacent side of the photosensor 1 and the vertical transfer section 2. The readout gate 5 includes the second gate 8 that reads signal charges to the transfer section 2.

When the peak value of the read pulse vH shown in FIG. 5 is low, when the waveform is dulled by the load, or when the pulse width
When is short, light enters the photosensor 11 in FIG. 4, and the signal charge excited and accumulated in the photosensor 11, which is far from the readout gate 15, stalls and is not vertically transferred within the readout period. This results in incomplete transfer in which the signal charges are not transferred to the photo sensor 12, and some of the signal charges are left behind in the photosensor 11, resulting in poor afterimage characteristics, and the deterioration of the afterimage characteristics becomes even worse at low illuminance.

In contrast to the conventional solid-state image sensor described above, in the first embodiment of the solid-state image sensor according to the present invention, as shown in FIG. 1 and the center of the adjacent sides of the vertical transfer section 2, and are configured so that the longest distance from the readout gate 5 within the photosensor becomes the shortest. When the peak value vH of the readout pulse is low,
If the waveform is distorted due to load, or the pulse width Vw
Even when the signal charge is short, signal charges excited and accumulated in the photosensor 1 that is far away from the readout gate 5 are less likely to be incompletely transferred to the vertical transfer unit 2 due to stalling during the readout period compared to the conventional example. Due to the incomplete transfer of the signal charges excited and accumulated in the photosensor 1 to the vertical transfer section 2, it is possible to reduce the deterioration of the afterimage characteristics caused by the signal charges left behind in the photosensor 1, especially in low-light imaging. In some cases, poor afterimage characteristics can be significantly suppressed.

2nd Q? 1 is a plan structural diagram of a cell section showing a second embodiment of the present invention, and similarly to the first embodiment of the present invention, it is similar to the plan structural diagram of a cell section in FIG. 4, which is an example of the prior art. It was adapted.

As shown in FIG. 2, the solid-state LFI image element according to the second embodiment of the present invention has a readout gate 5 from the photosensor 1 to the vertical transfer section 2 compared to the conventional example. Since the vertical transfer section 2 is arranged close to the center of the adjacent sides, for the same reason as the first embodiment of the present invention described above,
It goes without saying that the deterioration of the afterimage characteristics can be reduced compared to the conventional example, and the deterioration of the afterimage characteristics can be significantly suppressed, especially during low-illuminance imaging.

As described in detail, according to the present invention, the readout gate for reading signal charges from the photosensor 1 to the vertical transfer section 2 is located at the center of the adjacent side of the photosensor 1 and the vertical transfer section 2, or near the center. By configuring so that the longest distance between the readout gate 5 and the photosensor 1 is as short as possible, it is possible to detect when the wave height 1iaVo of the readout pulse is low, when the waveform is blunted by the load, or when the pulse gvw is short. However, compared to the conventional example, the readout game 1-
Incomplete transfer to the vertical transfer section 2 due to stalling during the readout period of the signal charges excited and accumulated in the photosensor 1 which is distanced from the photosensor 5 is less likely to occur, and the signal charges excited and accumulated in the photosensor 1 are It is possible to reduce the deterioration of the afterimage characteristics caused by signal charges left behind in the photosensor 1 due to incomplete transfer of the signals to the vertical transfer section 2. In particular,
During low-light imaging, it is possible to significantly suppress poor aCS characteristics.

[Brief explanation of the drawing]

121 is a plan structural diagram of a cell portion showing a first embodiment of the solid-state image sensor according to the present invention, and FIG. 2 is a plan view of a cell portion showing a second embodiment of the solid-state image sensor according to the present invention. Fig. 3 is a conceptual diagram of an interline type solid-state LFI image element, which is an example of the conventional technology, Fig. 4 is a planar structural diagram of its cell section, and Fig. 5 is a vertical transfer section and signals from the photosensor. FIG. 7 is a diagram showing an example of a clock pulse applied to a second gate that also serves as a charge readout gate. 1.11...Photo sensor, 2,12...Vertical transfer unit, 3.13...Horizontal transfer unit, 4.14...Signal output unit, 5°15...Reading gate, 6. 16...
Channelst whelk, 7.17...first gate, 8
, 18...Second Gate Figure 3 Patent Applicant NEC Co., Ltd. Agent Patent Attorney Yutabe Kumagai

Claims (1)

[Claims] a vertical transfer section comprising a plurality of photosensors that accumulate signal charges according to the amount of incident light; a first gate and a second gate that transfer signal charges read from the photosensors; a readout gate located at the center of the adjacent side of the sensor and the vertical transfer section and configured with the second gate and configured to read signal charges from the photosensor to the vertical transfer section within the vertical blanking period; A solid-state imaging device comprising: a horizontal transfer section that sequentially transfers signal charges transferred from the vertical transfer section for each horizontal scanning line to a signal output section; and a signal output section.