JPH089266A - Solid-state imaging device - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to switch between 8-phase drive for improving saturation characteristics and 5-phase drive for improving smear characteristics at the time of vertical transfer depending on the important characteristic items of the solid-state imaging device. An imaging device is provided. [Structure] The solid-state imaging device 10 is driven by vertical transfer pulses φV1 to φV8 and horizontal transfer pulses φH1 and φH2 output from a driver 11. Vertical transfer pulse φ
V1 to φV8 and horizontal transfer pulses φH1 and φH2 are vertical transfer pulses V1 to V1 output from the pulse generator 12.
8 and horizontal transfer pulses H1 and H2 are voltage-converted by the driver 11. The signal output from the solid-state image sensor 10 is converted into a television signal by the signal processing device 13. When the saturation characteristic is important, 8-phase driving is performed, and when the smear characteristic is important, 5-phase driving is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state image pickup device in which drive timing can be switched according to characteristics of importance.

[0002]

2. Description of the Related Art Currently, a plurality of photoelectric conversion elements are arranged two-dimensionally, and four vertical transfer gates including one read gate for each one of the plurality of photoelectric conversion elements. A vertical transfer unit for reading the signal charges accumulated in the photoelectric conversion unit and transferring the signal charges in the vertical direction; a horizontal transfer unit for transferring the signal charges transferred from the vertical transfer unit in the horizontal direction; A video camera (movie), which is a solid-state imaging device using a solid-state imaging device having a signal charge detection unit that converts the signal charge transferred from the transfer unit into a signal voltage or a signal current and outputs the signal camera, has become widespread. As it spreads, the required properties differ depending on the application.

A conventional example will be described with reference to the drawings. FIG. 2 shows a schematic diagram of a part of the configuration of the solid-state image sensor.
In the solid-state imaging device, photodiodes 1 which are photoelectric conversion elements are arranged two-dimensionally, and a vertical CCD 2 having a 4-phase vertical transfer gate is arranged beside the photodiode 1 with respect to one photodiode 1. . One of the four-phase vertical transfer gates also serves as the read gate 3 for transferring the charges accumulated in the photodiode 1 to the vertical CCD 2. Further, two vertically adjacent photodiodes 1 are set as one set, and eight-phase vertical transfer pulses φV1 to φV8 can be applied as a drive pulse from the outside of the solid-state image pickup device, and the charges are applied on the vertical CCD 2. Transferred toward the horizontal CCD (not shown) side (direction of arrow A in FIG. 2). The horizontal CCD has a structure having two-phase horizontal transfer gates.

FIG. 5 is a block diagram showing the structure of a conventional solid-state image pickup device including the solid-state image pickup device having the structure shown in FIG. In FIG. 5, the solid-state image sensor 4 has vertical transfer pulses φV1 to φV8 and horizontal transfer pulses φ output as drive pulses from the driver 5 that performs voltage conversion.
It is driven by H1 to φH2. Vertical transfer pulse φV1
.About..phi.V8 and horizontal transfer pulses .phi.H1 and .phi.H2 are vertical transfer pulses V1 to V8 output from the pulse generator 6.
The horizontal transfer pulses H1 and H2 are voltage-converted and combined by the driver 5. The vertical transfer pulses V1 to V8 are created by the vertical transfer pulse generator 16.

FIG. 6 shows a pulse generator 6 (MN522X;
Matsushita Electronic Components Co., Ltd.) shows a specific block diagram. Briefly explaining the operation of the pulse generator 6,
A clock having a frequency twice that of the horizontal transfer pulses H1 and H2 (output from the oscillation circuit OSC) and a horizontal synchronizing signal HD
And vertical synchronization signal VD are input, and these are appropriately divided to generate the above vertical transfer pulses V1 to V8 and horizontal transfer pulses H1 and H2, and horizontal transfer pulses H1 and H2 are output from the high-speed pulse decoder, Vertical transfer pulses V1 to V8 are output from the V transfer pulse decoder.

In the driver 5, for example, for the vertical transfer pulse, a binary pulse of 0.5 V or 0.3 V is converted into a ternary pulse of 15 V, 0 V, and -8 V and combined. The horizontal transfer pulse is converted into a pulse having a 5V amplitude, such as when the pulse generator 6 operates at 3V. The signal output from the solid-state image sensor 4 driven by the vertical transfer pulses φV1 to φV8 and the horizontal transfer pulses φH1 and φH2 is subjected to clamp / blanking processing or the like by the signal processing device 7 to be a television signal (TV signal). To be converted.

FIG. 4 shows a time chart of the vertical transfer pulse output from the driver 5 of FIG. 5 when the solid-state image sensor 4 is driven by five phases. FIG. 4 shows the horizontal synchronizing signal HD and the 8-phase vertical transfer pulses φV1 to φV8 in the vertical blanking period of the television signal. First, the read pulse 8 having a voltage of about 15V is applied to the read gate 3 to which the vertical transfer pulses φV3 and φV7 of FIG.
Is applied by shifting the timing, and the photodiode 1
The charges accumulated in the vertical CCD are transferred to the vertical CCD 2. The charges transferred to the vertical CCD 2 in FIG. 2 are transferred twice to the horizontal CCD in one horizontal scanning period as shown in FIG. 4 (refer to the reference numeral 9). In the read period, the charges accumulated in the photodiode 1 are transferred to the vertical CCD through the V3 and V7 gates, and in the transfer period, the charges transferred to the vertical CCD are transferred in the horizontal CCD direction (downward in the figure).

In order to perform the interlacing, the charges of the two photodiodes 1 are mixed in the horizontal CCD by changing the upper and lower pairs depending on the field. Focusing only on the vertical transfer (refer to the reference numeral 9) performed during the horizontal blanking period, the vertical transfer pulses φV1 to φV4 of four types of phases and the vertical transfer pulses φV5 to φV8 of four types of phases have the same phase. It is a 4-phase drive. Considering the read pulse 8, there are five phases. After that, set this drive timing to 5
This is called phase drive. In 5 phase drive, 8 vertical transfer gates
Since it can be driven by the vertical transfer pulse of any kind, the circuit scale of the driver 5 can be reduced. In addition, the smear characteristic is good.

Further, in a four-phase drive having two vertical transfer gates in one photodiode like a normal interline CCD, if the number of horizontal pixels increases when the size of the image pickup surface is fixed, The ratio of the horizontal length to the vertical length of one vertical transfer gate becomes small, that is, the vertical transfer gate becomes thin and it becomes difficult to transfer, and the transfer efficiency is lowered. However, in the case of the combination of the CCD and the 5-phase drive Like 1
5 with 4 vertical transfer gates per photodiode
In the phase drive, the transfer efficiency increases as the number of vertical transfer gates increases.

[0010]

However, in the above-mentioned structure, although the transfer efficiency is higher than that of the four-phase drive in which one photodiode has two vertical transfer gates, the minimum transfer at the time of vertical transfer is required. The gate becomes 2 of the 4 gates, and sufficient transfer efficiency cannot be obtained.
The saturation characteristics of D cannot be obtained sufficiently.

[0011] The transfer operation, as is apparent from the time chart of FIG. 4, for example at a certain time t _1, charges are accumulated in the vertical transfer gate V1, V2, V5, V6, at time of next t _2, Vertical transfer gates V1, V2, V3
V5, V6, V7 charge is accumulated, the next time t _3, by charges to the vertical transfer gate V2, V3, V6, V7 are accumulated, the charge sequentially from the vertical transfer gate V1 of the vertical transfer gate V8 Is transferred in the direction.

Regarding the transfer efficiency, the more the vertical CCD is moved (the shorter the cycle is), the lower the transfer efficiency becomes. The saturation characteristic is proportional to the size of the vertical CCD and is proportional to the minimum transfer gate. The minimum transfer gate is a gate when the CCD capacity becomes the smallest in the vertical CCD when transferring charges, and is, for example, the vertical transfer gates V1 and V2 at time t ₁ .

An object of the present invention is to increase the minimum transfer gate in vertical transfer as compared with that in four-phase driving (five-phase driving when a read pulse is taken into consideration) to improve 8-phase driving for improving saturation characteristics and smear characteristics. It is an object of the present invention to provide a solid-state imaging device capable of switching between phase driving (five-phase driving in consideration of a read pulse) depending on an application method, a usage method, and a characteristic item to be emphasized.

[0014]

A solid-state image pickup device according to the present invention includes a photoelectric conversion section in which a plurality of photoelectric conversion elements are two-dimensionally arranged, and one photoelectric conversion element for each photoelectric conversion element. A vertical transfer unit that has four vertical transfer gates including a read gate and reads out the signal charges accumulated in the photoelectric conversion unit and transfers the signal charges in the vertical direction, and the signal charges transferred from the vertical transfer unit in the horizontal direction. A solid-state imaging device having a horizontal transfer section that transfers the signal charges transferred from the horizontal transfer section and a signal charge detection section that converts the signal charges transferred from the horizontal transfer section into a signal voltage or a signal current and outputs the signal voltage or the signal current; Two photoelectric conversion elements adjacent to each other in the vertical direction are set as one set, respectively, and the photoelectric conversion elements are set to 1 in the horizontal blanking period of the television signal.
Vertical transfer pulses of eight kinds of phases given to eight vertical transfer gates of a pair of photoelectric conversion elements and vertical transfer pulses of four kinds of phases given to four vertical transfer gates of each photoelectric conversion element of the set. And a pulse generator for selectively generating and.

[0015]

With the above configuration, when the saturation characteristics are emphasized during vertical transfer, vertical transfer pulses of eight kinds of phases are applied to eight vertical transfer gates of one photoelectric conversion element, so that the minimum transfer gate has four phases. The number of gates is increased from that during driving (5-phase driving in consideration of a read pulse), and 6 gates out of 8 phases are used for 8-phase driving. Further, when importance is attached to smear characteristics, four-phase driving (reading) for improving smear characteristics is performed by applying vertical transfer pulses of four kinds of phases to the four vertical transfer gates of each photoelectric conversion element of one set. Considering the pulse, it is set to 5 phase drive). In this way, by switching between 8-phase driving and 4-phase driving (5-phase driving in consideration of the read pulse), it can be used in a state most suitable for the application method.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 shows a schematic diagram of a part of the configuration of the solid-state image sensor. In the solid-state imaging device, photodiodes 1 which are photoelectric conversion elements are arranged two-dimensionally, and a vertical CCD 2 having a 4-phase vertical transfer gate is arranged beside the photodiode 1 with respect to one photodiode 1. .
One of the four-phase vertical transfer gates also serves as the read gate 3 for transferring the charges accumulated in the photodiode 1 to the vertical CCD 2. In addition, two photodiodes 1 vertically adjacent to each other are set as one set, and an 8-phase vertical transfer pulse φ is used as a drive pulse from the outside of the solid-state image sensor.
V1 to φV8 can be applied, and charges are transferred on the vertical CCD 2 toward the horizontal CCD (not shown) (in the direction of arrow A in FIG. 2). The horizontal CCD has a structure having two-phase horizontal transfer gates.

FIG. 1 is a block diagram showing the configuration of a solid-state image pickup device of one embodiment of the present invention, which is configured to include the solid-state image pickup device having the configuration shown in FIG. In FIG. 1, the solid-state imaging device 10 is driven by vertical transfer pulses φV1 to φV8 and horizontal transfer pulses φH1 to φH2 output as drive pulses from a driver 11 that performs voltage conversion. Vertical transfer pulses φV1 to φV8 and horizontal transfer pulse φH
1, φH2 are vertical transfer pulses V1 to V8 and horizontal transfer pulses H1 and H2 output from the pulse generator 12.
Are voltage-converted and combined by the driver 11. The vertical transfer pulses V1 to V8 are created by the vertical transfer pulse generator 14.

The pulse generator 12 has the same structure as that of the conventional pulse generator 6 except that the limiting circuit 15 is added. The driver 11 has the same configuration as the driver 5 of the conventional example. The limiting circuit 15 will be described later. Solid-state imaging device 10 driven by vertical transfer pulses φV1 to φV8 and horizontal transfer pulses φH1 and φH2
The output signal is clamped by the signal processor 13.
A television signal (TV
Signal).

FIG. 3 shows a time chart of the vertical transfer pulse output from the driver 11 of FIG. 1 when the solid-state image pickup device 10 is driven by eight phases. FIG. 3 shows the horizontal synchronizing signal HD and the 8-phase vertical transfer pulses φV1 to φV8 in the vertical blanking period of the television signal. First, FIG.
The read pulse 8 having a voltage of about 15V is applied to the read gate 3 to which the vertical transfer pulses φV3 and φV7 are applied at different timings to transfer the charges accumulated in the photodiode 1 to the vertical CCD 2. Figure 2
Two photodiodes 1 transferred to the vertical CCD 2 of
The charges for the minutes are mixed on the vertical CCD 2, and the mixed charges are transferred from the vertical CCD 2 to the horizontal CCD once in one horizontal scanning period as shown in FIG. 3 (see a portion 16). In the read period, the charges accumulated in the photodiode 1 are transferred to the vertical CCD through the V3 and V7 gates, and in the transfer period, the charges transferred to the vertical CCD are transferred in the horizontal CCD direction (downward in the figure).

It is realized by changing the upper and lower pairs of charges of the two photodiodes 1 and mixing them in the vertical CCD 2 depending on the field for interlacing.
Focusing only on the vertical transfer (refer to the part indicated by reference numeral 16) in the horizontal blanking period, the vertical transfer pulses φV1 to φV8 are in different phases, and are 8-phase drive. Hereinafter, this drive timing is referred to as 8-phase drive. With this 8-phase drive,
At the time of vertical transfer, the minimum transfer gate becomes 6 of the 8 gates, which is 1.5 times the transfer gate of 5 phase drive, and sufficient transfer efficiency is obtained, and the saturation characteristic of the vertical CCD is 1.5 of 5 phase drive. A double improvement is seen.

However, in this 8-phase driving, charges are accumulated in 6 gates on the vertical CCD 2 during the image scanning period. At the time of 5-phase driving, there are 4 gates out of 8 gates. Therefore, when light is incident on a portion other than the photodiode, particularly when charges are generated in the lower portion of the vertical CCD 2, smear is accumulated in the vertical CCD 2, but 8-phase driving is more likely to occur 1.5 times than 5-phase driving.

Therefore, when the saturation characteristic is emphasized, the 8-phase drive is performed, and when the smear characteristic is emphasized, the 5-phase drive is performed as described in the conventional example (see the time chart of FIG. 4). As is clear from comparison between FIG. 3 and FIG. 4, the 8-phase driving is achieved by limiting and erasing a part of the pulse timing at the time of 5-phase driving like the vertical transfer timing (see reference numeral 9) in FIG. Easy to achieve. Therefore, as shown in FIG. 1, by adding the limiting circuit 15 to the vertical transfer pulse generating unit 14 and giving a switching command to the limiting circuit 15, the 5-phase driving and the 8-phase driving can be easily performed.
It is possible to switch the phase drive, and it is possible to improve the characteristics of the solid-state imaging device (camera) according to the characteristics to be emphasized.

The limiting circuit 15 uses a normal logic (logical product, logical sum, inversion, etc.) to fix a part of the vertical transfer pulse 9 to the H level or the L level, and the vertical transfer pulse 16 is fixed. To make. Further, the read pulses of V3 and V7 are staggered in timing, but they may be at the same timing. However, if the timing is the same, CCD characteristics may deteriorate.

[0024]

The solid-state image pickup device of the present invention is applied by selecting 8-phase drive when the saturation characteristic is emphasized and 4-phase drive (5-phase drive considering the read pulse) when the smear characteristic is emphasized. The drive timing most suitable for the method can be used.

[Brief description of drawings]

FIG. 1 is a block diagram of a solid-state imaging device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a solid-state image sensor according to an embodiment of the present invention and a conventional example.

FIG. 3 is a time chart showing vertical CCD drive timing in one embodiment of the present invention.

FIG. 4 is a time chart showing vertical CCD drive timing in one embodiment of the present invention.

FIG. 5 is a block diagram of a conventional solid-state imaging device.

FIG. 6 is a block diagram showing a specific circuit configuration of a pulse generator.

[Explanation of symbols]

 1 Photodiode 2 Vertical CCD 3 Readout gate 4,10 Solid-state image sensor 5,11 Driver 6,12 Pulse generator 7,13 Signal processor 8 Readout pulse 9,16 Vertical transfer pulse 14 Vertical transfer pulse generator 15 Limiting circuit

Claims (1)

[Claims] 1. A photoelectric conversion unit in which a plurality of photoelectric conversion elements are two-dimensionally arranged, and four vertical transfer gates including one read gate for each one of the plurality of photoelectric conversion elements. A vertical transfer unit that reads out the signal charge accumulated in the photoelectric conversion unit and transfers it in the vertical direction, a horizontal transfer unit that transfers the signal charge transferred from the vertical transfer unit in the horizontal direction, and the horizontal transfer unit. A solid-state imaging device having a signal charge detection unit that converts the signal charge transferred from the device into a signal voltage or a signal current and outputs the signal voltage, and two photoelectric conversion devices of the vertical transfer unit that are adjacent to each other in the vertical direction. Each as one set, and each of the vertical transfer pulses of eight kinds of phases given to the eight vertical transfer gates of the one set of photoelectric conversion elements during the horizontal blanking period of the television signal and the one set of photoelectric conversion elements. Of 4 The solid-state imaging device having selectively a pulse generator for generating the vertical transfer pulses of the four phases giving to the vertical transfer gate.