JPH114384A - Solid-state image pickup element and its drive method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent adverse effect due to a change in an output from an output section during blanking period by keeping the output section to a reset state with a reset means for a horizontal and/or vertical blanking period so as to prevent the change in the output of the output section. SOLUTION: A detected light by each pixel 1 is subject to photoelectric conversion and amplified and given to a vertical signal line 3 via a transistor(TR) 2 that is switched through vertical scanning of each pixel 1. A TR 5 is used to give a signal stored in a signal storage capacitor (ca) to a horizontal signal line 6. An output section 7 receives a voltage VB at a noninverting input terminal and receives a signal from the horizontal signal line 6 at an inverting input terminal and provides an output of an output signal of a solid-state image pickup element from its output terminal. Then a reset means 8 repeats resetting the output section 7 naturally for a valid period every time a signal by one pixel finishes its output for a prescribed period and is made conductive for an invalid period (for a horizontal and/or vertical blanking period) to keep the output section 7 to a reset state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid-state imaging device, and more particularly to a photoelectric conversion and amplification of light detected by each pixel, reading out the signal in the form of an electric signal to a vertical signal line, and outputting a signal comprising, for example, a capacitor. Temporarily store (hold) in holding means
Further, the present invention relates to an amplification type solid-state imaging device which transmits a signal stored (held) to a horizontal signal line via a switching unit switched by a horizontal scanning operation and outputs the signal via an output unit, and a driving method thereof.

[0002]

2. Description of the Related Art As a solid-state imaging device, light detected by each pixel is photoelectrically converted and amplified by the pixel, read out to a vertical signal line in the form of an electric signal, and temporarily stored in a signal holding means such as a capacitor. Accumulate (hold) and accumulate (hold)
There is a so-called amplification type solid-state imaging device that transmits the output signal to a horizontal signal line through a switching unit that is switched by a horizontal scanning operation, and outputs the output signal through an output unit. Is, for example, Japanese Patent Application No. 2
-278415 (Japanese Patent Application Laid-Open No. 4-154281) and various other proposals.

[0003] Such a solid-state imaging device converts light detected by each pixel into signal charges, and then transfers the signal charges as they are by vertical and horizontal transfer by a vertical transfer register and a horizontal transfer register, and conveys them to an output amplifier. So-called CCD
Unlike solid-state imaging devices of the type, the charge is not transferred from each pixel to the output section as it is, so the adverse effect that noise enters during charge transfer by the CCD is small, and the noise can be easily reduced. Having.

FIGS. 2A to 2C are diagrams for explaining an example of such an amplification type solid-state imaging device.
(A) is a configuration diagram showing a schematic configuration of a solid-state imaging device, (B)
3 is a circuit diagram showing a reset unit, and FIG. 3C is a timing chart showing driving of the reset unit. In the drawing,
Reference numeral 1 denotes each pixel (pixel 1 pixel), which includes a photoelectric conversion element, a current collecting region, a reset MOS transistor, an amplification transistor, and the like, but details thereof are not directly related to the problem to be solved by the present invention, and will not be described. Omitted. (1,
4), (2, 4), etc. indicate x, y coordinates of each pixel 1. The detection light of each pixel 1 is photoelectrically converted and amplified, and transmitted to a vertical signal line 3 via a transistor 2 that is switched by vertical scanning of each pixel 1.

[0005] Ca is a signal holding capacitor, two capacitors are provided corresponding to each vertical signal line 3. In the example shown in FIG. 2, two signals corresponding to each vertical signal line 3 are provided so that the signal of the even line and the signal of the odd line can be held in different signal holding capacitors so that all pixels can be read out. In the case of a solid-state imaging device that does not need to read out all pixels, one signal holding capacitor ca is provided for each vertical signal line 3. I just need. Reference numeral 4 denotes a switching transistor for transmitting a signal from each vertical signal line 3 to the signal holding capacitor ca.
1, SH2 (SH2 is unnecessary if all pixels are not read out). Reference numeral 5 denotes a switching transistor that is provided corresponding to each signal holding capacitor ca and transmits a signal held by the signal holding capacitor ca to the horizontal signal line 6, and is switched by a horizontal scanning operation.

Reference numeral 7 denotes an amplifier serving as an output unit. The amplifier 7 receives a voltage VB at a non-inverting input terminal and receives the horizontal signal line 6 at an inverting input terminal.
And outputs the signal from the output terminal as an output signal of the solid-state imaging device. Reference numeral 8 denotes reset means.
As shown in (B), the switching element is formed by a CMOS transistor, is switching-controlled by signals RN and RP, and is connected between the inverting input terminal and the output terminal of the amplifier 7.

The reset means 8 sets the signal RN to "high".
Then, when RP becomes "low", it conducts and resets the output of the amplifier 7 to a level equal to the level VB of its non-inverting input terminal. Conversely, when the signal RN is “low”
Then, when RP becomes "high", the state becomes non-conductive, and the amplifier 7 outputs a signal of a level corresponding to the signal input to its inverting input terminal. The reset means 8 is turned on each time the amplifier 7 outputs a signal of one pixel, and plays a role of resetting the amplifier 7.

Conventionally, the reset means 8
As shown in FIG. 2C, the ON / OFF control is always performed at a constant period during the operation of the solid-state imaging device regardless of the valid period or the invalid period.

[0009]

In the prior art, as described above, the reset means 8 is always turned on and off at a constant cycle during the operation of the solid-state imaging device regardless of the valid period or the invalid period. Therefore, a change in the output of the solid-state imaging device during the ineffective period due to the on / off control often affects the original signal of the solid-state imaging device or adversely affects signal processing in a subsequent stage. Further, during the minute ranking period, there is a large change in the substrate voltage and a vertical scanning operation, so that the output of the output amplifier 7 is affected and becomes unstable, which adversely affects others.

The present invention has been made to solve such a problem. Light detected by each pixel is photoelectrically converted and amplified by each pixel, and read out to a vertical signal line in the form of an electric signal. Amplifying type solid-state, which temporarily stores signal holding means composed of, for example, a capacitor, transmits the stored signal to a horizontal signal line via switching means switched by horizontal scanning, and outputs the output signal via an output unit. It is an object of the present invention to prevent a change in output of an output unit during a blanking period in an image sensor, thereby preventing an adverse effect due to the change.

[0011]

SUMMARY OF THE INVENTION The present invention is characterized in that the output unit is or is held in a reset state by reset means during horizontal and / or vertical blanking periods.

Therefore, according to the present invention, the output section is held in the reset state by the reset means during the horizontal and / or vertical blanking periods, so that the output is stable and does not change during the invalid period. Therefore, it is possible to prevent the output change of the output unit during the invalid period from adversely affecting others.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is configured such that the output section is held in a reset state by reset means during a horizontal and / or vertical blanking period. The present invention can be applied to a mode in which the reset state is maintained only during the horizontal blanking period, a mode in which the reset state is maintained only during the vertical blanking period, and a method in which both the vertical blanking period and the horizontal blanking period are reset. The present invention can also be implemented in a form in which the state is maintained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the illustrated embodiments. FIGS. 1A to 1C are diagrams for explaining such a first embodiment of the solid-state imaging device of the present invention.
(A) is a configuration diagram showing a schematic configuration of a solid-state imaging device, (B)
3 is a circuit diagram showing a reset unit, and FIG. 3C is a timing chart showing driving of the reset unit. In the drawing,
Reference numeral 1 denotes each pixel (pixel 1 pixel), which includes a photoelectric conversion element, a current collecting region, a reset MOS transistor, an amplification transistor, and the like, but details thereof are not directly related to the essence of the present invention, and thus description thereof is omitted. I do. (1,4),
(2, 4) and the like indicate the x and y coordinates of each pixel 1. Each pixel 1
The detection light is photoelectrically converted and amplified, and transmitted to the vertical signal line 3 via the transistor 2 that is switched by the vertical scanning of each pixel 1.

Reference numeral ca denotes a signal holding capacitor, two capacitors corresponding to each vertical signal line 3. In this example, two signals are held in correspondence with each vertical signal line 3 so that even-line signals and odd-line signals can be held in different signal holding capacitors so that all pixels can be read out. Although a capacitor is provided, in the case of a solid-state imaging device that does not need to read out all pixels, a signal holding capacitor ca may be provided for each vertical signal line 3. In this embodiment,
Since two signal holding capacitors Ca are provided corresponding to each vertical signal line, all pixels can be read. In this case, one pixel (pixel) is output. A switching transistor 4 transmits a signal from each vertical signal line 3 to a signal holding capacitor ca.
H1, SH2 (SH2 when all pixels are not read out)
Is unnecessary. ). Reference numeral 5 denotes a switching transistor that is provided corresponding to each signal holding capacitor ca and transmits a signal held by the signal holding capacitor ca to the horizontal signal line 6, and is switched by a horizontal scanning operation.

Reference numeral 7 denotes an amplifier which constitutes an output unit.
And outputs the signal from the output terminal as an output signal of the solid-state imaging device. Reference numeral 8 denotes reset means.
As shown in (B), the switching element is formed by a CMOS transistor, is switching-controlled by signals RN and RP, and is connected between the inverting input terminal and the output terminal of the amplifier 7.

The reset means 8 sets the signal RN to "high".
Then, when RP becomes "low", it conducts and resets the output of the amplifier 7 to a level equal to the level VB of its non-inverting input terminal. Conversely, when the signal RN is “low”
Then, when RP becomes "high", the state becomes non-conductive, and the amplifier 7 outputs a signal of a level corresponding to the signal input to its inverting input terminal. The reset means 8 is turned on each time the amplifier 7 outputs a signal of one pixel, and plays a role of resetting the amplifier 7.

The resetting means 8 of this embodiment keeps repeating the operation of resetting the output unit 7 every time the signal of one pixel is output for a valid period at a constant period.
As shown in (C), during the invalid period (during the horizontal and / or vertical blanking period), the output section 8 is kept in the reset state by being made conductive. That is, during that ineffective period,
Since the signal RN is kept at "high" and the RP is kept at "low", the reset means 8 keeps conducting.
Therefore, during the invalid period, the output of the output unit 7 is kept at the same level as the VB level received at the inverting input terminal, and the output level is stabilized.

Therefore, according to the present embodiment, it is possible to prevent a change in the output of the output unit during the invalid period from adversely affecting others.

[0020]

According to the present invention, since the output section is held in the reset state by the reset means during the horizontal and / or vertical blanking periods, the output is stabilized during the invalid period,
It does not change. Therefore, it is possible to prevent the output change of the output unit during the invalid period from adversely affecting others.

[Brief description of the drawings]

FIGS. 1A to 1C are diagrams for explaining a first embodiment of a solid-state imaging device according to the present invention; FIG. 1A is a configuration diagram illustrating a schematic configuration of the solid-state imaging device; 3 is a circuit diagram showing a reset unit, and FIG. 3C is a timing chart showing driving of the reset unit.

FIGS. 2A to 2C are diagrams for explaining a conventional example of an amplification type solid-state imaging device, wherein FIG. 2A is a configuration diagram illustrating a schematic configuration of the solid-state imaging device, and FIG. FIG. 3C is a timing chart showing the operation of the reset means.

[Explanation of symbols]

1 ... pixel, 3 ... vertical signal line, ca ... signal holding means (signal holding capacitor), 6 ... horizontal signal line, 7 ... output unit, 8 ... reset means.

Claims (2)

[Claims] 1. A plurality of photoelectric conversion elements and a plurality of transistors that amplify signal charges stored therein and convert the signal charges into electric signals, are arranged two-dimensionally in a vertical direction and a horizontal direction, and are vertically scanned to output the electric signals. Pixel, a vertical signal line provided corresponding to each vertical column of the pixel, and transmitting an electric signal output from the pixel, and a vertical signal line provided corresponding to each vertical signal line, and transmitted through the vertical signal line. A signal holding means for temporarily holding the obtained electric signal, a horizontal signal line, and a signal holding means provided in correspondence with each of the signal holding means, which are switched by a horizontal scanning operation and temporarily held in the signal holding means. Switching means for transmitting the electric signal transmitted to the horizontal signal line, an output unit for outputting the electric signal transmitted to the horizontal signal line, and resetting the output unit every time the transmission of the signal from each pixel is completed. And a reset means for holding the output section in a reset state by the reset means during a horizontal and / or vertical blanking period. A solid-state imaging device characterized by the above-mentioned. 2. A plurality of photoelectric conversion elements and a plurality of transistors which amplify signal charges stored therein and convert the signal charges into electric signals, and which are two-dimensionally arranged in the vertical and horizontal directions and vertically scanned to output the electric signals. A pixel, a vertical signal line provided corresponding to each vertical column of the pixel, and transmitting an electric signal output from the pixel, and a vertical signal line provided corresponding to each vertical signal line and transmitted through the vertical signal line. Signal holding means for temporarily holding the electric signal, a horizontal signal line,
A switching unit that is provided corresponding to each of the signal holding units and that transmits an electrical signal that is switched by a horizontal scanning operation and temporarily held by the signal holding unit to the horizontal signal line; A method for driving a solid-state imaging device, comprising: an output unit that outputs an electric signal; and a reset unit that resets the output unit each time transmission of a signal from each pixel is completed. Holds the output section in a reset state by the reset means. A method for driving a solid-state imaging device, comprising: