JPH11127459A - Method for inspecting solid-state image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deterioration of the waveform of transfer leaving signal of signal charge appearing on the first picture element of an OB(optical black) part area, and to precisely measure the waveform. SOLUTION: A clamp pulse is applied to a signal waveform outputted for each picture element by a clamp circuit 5, and a sample/hold(S/H) pulse is applied by an S/H circuit 6. In sampling, the S/H pulse is stopped before several picture elements from the first picture element of an OB part 11 so that the effect of the time constant of the clamp circuit 5 can be prevented, and the S/H pulse is applied again after being made close to a low level. Thus, the deterioration of the waveform after S/H can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting a solid-state imaging device as an image sensor applied to a facsimile, an image scanner, or the like, or a solid-state imaging device of an integrated video camera.

[0002]

2. Description of the Related Art In recent years, solid-state image pickup devices have been widely used as image pickup units of integrated video cameras and image recognition sensors of facsimile and image scanners. In particular, CCD type solid-state image pickup devices (CCD: Charge Cou
pled Device) is most often used. In addition, high accuracy of inspection is strongly desired.

FIG. 3 shows a method for inspecting the transfer deterioration (hereinafter referred to as transfer efficiency) of a charge transfer section of a conventional solid-state imaging device.

In FIG. 3, reference numeral 21 denotes a light receiving area of the image sensor. The signal charges generated by the photoelectric conversion by the photodiode 22 are transferred by the charge transfer unit 23, converted into a signal voltage by the output unit 24, and output. A clamp pulse is applied to the signal output waveform output for each pixel by a clamp circuit 25, an S / H pulse is applied by an S / H (sample hold) circuit 26, and an A / D converter 28
, And stored in the frame memory 29. Based on the pixel information, the arithmetic processing unit 30 converts the digital data into a non-light receiving area OB 3
The transfer efficiency was calculated by measuring the first pixel of No. 1 as the transfer residue.

[0005]

However, the S / H
When S / H pulses are applied to the signal output waveform by the circuit, if pulses are applied to all the signal output waveforms, OBs in the non-light receiving area are held compared with the signal output, but are held between pulses.
Since the transfer residual signal of the first pixel in the portion is a small signal, there is a problem that the signal waveform is deteriorated by the influence of the time constant (CR) of the clamp circuit.

[0006]

According to the present invention, there is provided a method for inspecting a solid-state imaging device, comprising: a light receiving section; a charge transfer section for transferring signal charges generated in the light receiving section; and a charge transferred from the charge transfer section. A method for inspecting a solid-state imaging device including a charge detection unit, wherein when sampling a waveform output from the charge detection unit, the S / H pulse is stopped for a certain period to prevent the OB unit, which is a non-light receiving region, from sampling. The transfer of the pixel is left, and the signal is S / H.
The pulse is applied again.

[0007]

Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic plan view showing a method for inspecting a solid-state imaging device according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a light receiving area of the image sensor. The signal charges generated by the photoelectric conversion by the photodiode 2 are transferred by the charge transfer unit 3, converted into a signal voltage by the output unit 4, and output. The clamp circuit 5 applies a clamp pulse to the signal output waveform output for each pixel,
An S / H pulse is applied by an H (sample and hold) circuit 6, digitized by an A / D converter 8 via an amplifier 7, stored in a frame memory 9, and processed in a non-light receiving area by an arithmetic processing unit 10 based on pixel information. Then, the first pixel of the OB unit 11 is measured as the transfer remaining, and the transfer efficiency is calculated.

Here, when a pulse is applied and sampled like an S / H pulse waveform, one of the OB sections 11 which is a non-light receiving area is controlled so as not to be affected by the time constant (CR) of the clamp circuit 5. The S / H pulse is stopped several pixels before the pixel, and the S / H pulse is applied again to the remaining transfer signal of the first pixel of the OB unit 11 by approaching the low level, thereby deteriorating the waveform after the S / H. Can be eliminated.

[0011]

As described above, according to the inspection method for a solid-state imaging device of the present invention, the horizontal charge transfer efficiency of the horizontal charge transfer unit is measured with high precision by stopping the S / H pulse for a certain period. be able to. Of course, it is needless to say that the present invention can be applied to a two-dimensional solid-state imaging device.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing an inspection method of a solid-state imaging device according to an embodiment of the present invention.

FIG. 2 is a view for explaining signal processing timing of the inspection method of the solid-state imaging device according to one embodiment of the present invention;

FIG. 3 is a schematic plan view showing a conventional solid-state imaging device inspection method.

FIG. 4 is a view for explaining signal processing timing in a conventional method of inspecting a solid-state imaging device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light receiving area of image sensor 2 photodiode 3 charge transfer section 4 output section 5 clamp circuit 6 S / H (sample / hold) circuit 7 amplifier 8 A / D converter 9 frame memory 10 arithmetic processing section 11 OB section

Claims (1)

[Claims] A light-receiving unit arranged one-dimensionally or two-dimensionally; a charge transfer unit for transferring a signal charge generated in the light-receiving unit; and a charge detection unit for detecting a charge transferred from the charge transfer unit. A method for inspecting a solid-state imaging device, comprising: when sampling an output of the charge detection unit, stopping a pulse for a certain period of time and measuring transfer deterioration of the charge transfer unit. Inspection method.