JPS61141273A - Solid-state image pick-up device - Google Patents

Abstract

PURPOSE:To suppress an error signal of a horizontal profile part by controlling the horizontal aperture compensation degree by a control pulse produced from a defective-picture element position pulse. CONSTITUTION:A horizontal aperture compensation control circuit 7 is provided. The defective-picture element position pulse that is outputted from a defective- picture element position storing circuit 3 is adjusted of its width and phase, and then the degree of horizontal aperture compensation is controlled by a gain control circuit 10. Therefore, the correction error signal in the video signal output caused by the correcting of the defective picture element by means of the signal that precedes by one picture element, can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a solid-state imaging device useful for use in, for example, a video camera.

There are various types of conventional solid-state image sensors, but here MO8 is used.
The occurrence of white spot defects and black spot defects will be described in detail using an example of an imaging element using a photodiode called a type imaging element and an MO8 field effect transistor.

FIG. 3 is an example showing the operating principle of the MO8 type image sensor. A horizontal shift register 20 in which a large number of photodiodes 31, which are photosensitive elements, are arranged in a matrix, and for sequentially reading out signal charges accumulated in the photodiodes. Vertical shift register 30° and horizontal changeover switch 41.42.
43,...4n.

Vertical changeover switches 51, 52, 53.・・・・・・6m
is provided. As is well known, the horizontal shift register 2o is driven by a start pulse synchronized with a horizontal synchronizing signal and a horizontal clock pulse, and is driven by switches 41, 42,
43. . . . 4n is sequentially opened and closed so that all switches are operated in one horizontal scanning period.

On the other hand, the vertical shift register 3o is driven by a start pulse synchronized with the vertical synchronization signal and a clock pulse synchronized with the horizontal synchronization signal, and switches 51, 52, 53, .・・・
...5m are sequentially opened and closed to operate all switches within one vertical scanning period.

By operating these two types of switches, the signal charge accumulated in the food diode is sequentially supplied to a load circuit constituted by a resistor 21 and a power supply 22, and is taken out as a voltage signal.

Here, if the photodiode 31m is destroyed for some reason and the substrate and the carrier are short-circuited, the signal from the photodiode 31m will always reach the signal saturation point. Further, a large signal voltage is also generated when leakage occurs in the photodiode and the dark current of the photodiode is abnormally large. These defects are collectively called white spot defects, and the level of the latter changes depending on the operating temperature, operating voltage, etc. of the image sensor.

Further, in contrast to the above, when the photodiode stops responding to incident light, the signal becomes zero, resulting in a black spot defect.

Figure 4 (IL) shows the black spot defect status of the horizontal line signal.
φ) shows the state of the white spot defect of the horizontal line signal. The diagonal lines in the figure indicate 7 otodiodes 31 depending on the amount of light received.
indicates the amount of signal generated in

As a conventional solid-state imaging device for correcting such black spot defects and white spot defects, there is one shown in FIG. 6, for example. 1 is a solid-state image sensor, 2 is a pulse generator that generates drive pulses and sampling pulses for the solid-state image sensor, 3 is a defective pixel position memory circuit synchronized with the drive pulse, and 4 is a defect in the signal output from the solid-state image sensor. The 117th)-9-77'#$-"de circuit samples pixel signals other than pixels using output pulses from the defective pixel position storage circuit.
6 is a second sample and hold circuit that samples the output signal from the eleventh sample and hold circuit using pulses from the pulse generator 2, and 12 processes the output signal from the second sample and hold circuit and sends it out as a video signal. This is a signal processing circuit for

The operation of the conventional example shown in FIG. 5 will be described below with reference to FIG. 6.

Assuming that there is a defect in the pixel indicated by D as shown in FIG. The sampling pulse of the part corresponding to the defective pixel is stopped as shown in (b) of the same figure, and the output of the first sample hold circuit is The signal in front of the pixel is held as is. By sample-holding this signal with the second sample-hold pulse shown in (d), the defective pixel is replaced by the signal C of one pixel before, thereby correcting the defective pixel.

Problems to be Solved by the Invention However, in a solid-state imaging device configured as described above, if the brightness level of the subject has a relationship with the pixels of the solid-state imaging device as shown in FIG. 7, that is, a defective pixel occurs. , when there is no correlation between the brightness level of the previous pixel and 0, an error signal is generated due to defective pixel correction. In FIG. 7, assuming that the shaded areas are low brightness levels and the rest are high brightness levels, each horizontal scanning line (n)H, (n+1)H, (n+2)! ! The output signals of are shown in FIGS. 8(IL), (b), and (0), respectively. Horizontal scan line (n
+1) In H, the defective pixel is replaced by signal C from one pixel before, so even though the brightness level of the subject changes between pixel C and 0, the video signal output does not change. become. As described above, the solid-state imaging device having the conventional defective pixel correction circuit shown in FIG. 6 has the problem that defective pixels are not sufficiently corrected in horizontal contours that have no correlation with the subject, and an error signal is generated. was.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a solid-state imaging device that suppresses error signals at horizontal contours caused by a defective pixel correction circuit.

Means for Solving the Problems In order to solve the above problems, the solid-state imaging device of the present invention includes:
A defective pixel position storage circuit synchronized with the drive pulse of the solid-state image sensor, and a sample hold circuit that samples the pixel output signal excluding the defective pixel from the output signal of the solid-state image sensor driven by the output pulse from the defective pixel position storage circuit. and a control circuit for controlling the frequency band of a luminance signal obtained from the output signal of the defective pixel correction circuit using the defective pixel position pulse output from the defective pixel position storage circuit, It is configured to suppress the frequency band of the luminance signal.

According to the above-described configuration, the present invention corrects a correction error signal in the video signal output by correcting the defective pixel with the signal of one pixel before when the defective pixel comes to the horizontal contour part with no correlation of the object. This can be suppressed by reducing the horizontal aberration compensation amount at the defective pixel position.

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings.

FIG. 1 shows a block diagram of a solid-state imaging device according to an embodiment of the present invention. In FIG. 1, 1 to 6 are the same as those in the conventional example, so their explanation will be omitted.

6 is a low-pass F wave device C which removes the sampling pulse included in the signal output from the sample-and-hold circuit and obtains a luminance signal (hereinafter abbreviated as LPF), 7 is a horizontal avertia compensation circuit, and 8 is a defective pixel position. A control pulse adjustment circuit for adjusting the width and phase of the defective pixel position pulse output from the memory circuit to control the amount of horizontal abutment compensation; 9 is a horizontal abutment compensation signal generating circuit; 1o is a horizontal abutment compensation signal generating circuit; A gain control circuit 11 controls the amount of the Avertia compensation signal, and an addition circuit 11 adds the gain-controlled horizontal Avertia compensation signal to the luminance signal.

Embodiment 0 Solid-state imaging device configured as E″015
The operation of the first position will be explained based on the signal waveform example shown in FIG.

When the brightness level changes in the horizontal direction shown in Figure 7 (
The luminance signal obtained by removing the leakage component of the sampling pulse in the output signal from each horizontal scanning line at n)H, (n+1)H, and (n+2)H by LPFa is
They are shown in Figures (&), (b), and (0), respectively. L, P
The luminance signal outputted from F6 has its frequency characteristics improved by a horizontal Avthia compensation circuit 7, thereby compensating for the reduction in horizontal resolution due to Avachia distortion in the cathode ray tube of the television receiver. Figures 2(d) and (6) show the output of the horizontal averthere compensation circuit when ordinary horizontal avertear compensation is applied to the output signals at the horizontal scanning lines y(n)H and (n+1)H. Shows the signal waveform. (It is assumed that the peak of the compensation frequency in the horizontal avertia compensation circuit is selected at a frequency corresponding to one pixel.) (d
) and (6), it is clear that the error caused by defective pixel correction using the horizontal aberration compensation signal spreads to the three pixels C, D, and IC in the horizontal scanning line, as shown in (e). The signal will be emphasized by the horizontal avertia compensation circuit. For this reason, in the horizontal abutment compensation circuit of the present invention, the horizontal abutment compensation signal generated by the horizontal abutment compensation signal generation circuit 9 is converted from the defective pixel position pulse shown in FIG. 2(f) to the pulse adjustment circuit. By suppressing the control pulse (-) in the gain control circuit 1o with the pulse width and phase adjusted by 8, the horizontal scanning line (n+
1) H output signal is false) As shown in (1) H output signal is false, it is possible to prevent an increase in the defective pixel correction error signal due to horizontal avertia compensation.

As described in detail, according to the present invention, a gain control circuit is provided to control the amount of horizontal aperture compensation signal, and a control pulse generated from a defective pixel position pulse output from a defective pixel position storage circuit is provided. By controlling the amount of horizontal avertia compensation, it is possible to suppress the error signal of the horizontal contour portion of the defective pixel correction circuit using horizontal correlation, and the effect is extremely large.

[Brief explanation 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 an operational diagram of the same embodiment, Fig. 3 is a diagram showing the operating principle of the solid-state imaging device, and Fig. 4 is a diagram showing defective pixels. FIG. 6 is a block diagram showing a solid-state imaging device that performs conventional defective pixel correction.
7 is a schematic diagram showing the relationship between the pixels of the image sensor and the subject, and FIG. 8 is an operational waveform diagram of the conventional example at the time of FIG. 5. DESCRIPTION OF SYMBOLS 1... Solid-state image sensor, 2... Pulse generation circuit, 3... Defective pixel position memory circuit, 4, 6
...Sample hold circuit, 6...L
PF, 7...Horizontal avertia compensation circuit, e...
...Horizontal avertia compensation signal generation circuit, 1o...
...gain control circuit, 11...addition circuit, 8.
...Pulse adjustment circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 3 Figure 4 Figure 1A Figure 5 Figure 6 Figure 7 I-Baku 4 Akira/I High 14 Figure 8

Claims (2)

[Claims] (1) A defective pixel position memory circuit synchronized with the drive pulse of the solid-state image sensor, and a pixel output signal excluding defective pixels from the output signal of the solid-state image sensor driven by the output pulse from the defective pixel position memory circuit is sampled. A defective pixel correction circuit having a sample and hold circuit, and a control circuit that controls a frequency band of a luminance signal obtained from an output signal of the defective pixel correction circuit using a defective pixel position pulse output from the defective pixel position storage circuit, A solid-state imaging device characterized by suppressing a frequency band of a luminance signal at a defective pixel position. (2) A gain control circuit that controls the horizontal aperture compensation amount of the luminance signal obtained from the output signal of the defective pixel correction circuit is used to suppress the horizontal aperture compensation signal at the defective pixel position. A solid-state imaging device according to scope 1.