JPS601981A - Solid state image pickup device - Google Patents

Abstract

PURPOSE:To improve the utilizing factor of a solid-state image pickup device and to attain display without making defect remarkably on a display screen by detecting a defective element and correcting the level to a level closer to a correct signal level so as to form an output signal. CONSTITUTION:Figure shows a circuit block diagram for detecting a defective picture element, a signal photoelectric-converted by a CCD element 1 is amplified by a video amplifier 2 and converted into a TV signal by an encoder 3. The converted signal is inputted to a comparator 4 for detecting white defect level and a comparator 5 for detecting black defect level. If a voltage being very likely a signal from a defective element is inputted in this case, it is detected by the comparator 4 or 5, and a gate signal G1 for correction setting the period of the signal from the defective element is outputted through an OR circuit 6. The video signal is delayed for 4 picture elements' share (6 picture elements' share depanding on the color arrangement of a filter) as the detection of the defective element and each picture element is compared with picture elements at both horizontal sides.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention provides a number of 1! ! ! The present invention relates to a solid-state image pickup device (CCD) using a solid-state image pickup device (CCD) formed with a defective solid-state image pickup device.

<Conventional Techniques> As a next-generation image sensor, CCDs have many advantages over conventional image pickup tubes, so 1) 11 shots are being promoted in the outer mj. However, the CCD used as an image sensor], Q In1
Approximately 200,000 liters on a J-square chip! Since the rl pixels are made up of 1, the yield is extremely low and the cost is high.

<Object of the Invention> The present invention eliminates the drawbacks of the conventional fiVf and adds a simple circuit 411'f, thereby increasing the utilization rate of the solid-state image sensor and making defects less noticeable on a single display screen. A solid-state imaging device capable of displaying images is provided.

<Embodiment> Even if a defective pixel exists in a solid-state image sensor, the present invention makes it less noticeable on the display screen by automatically correcting the signal of the defective pixel using a circuit.

Generally, when a CCD has a defective pixel, a black dot or a white dot appears on the TV screen corresponding to the defective pixel. An attempt is made to repair the defective element by correcting such a black point or white point pixel, coloring it, and making it similar to the surrounding color.

First, a circuit for detecting defective elements from a plurality of CCDs arranged will be described.

If you carefully observe the video output of a CCU with a defective pixel, as shown in Figure 1, in the case of black point A, the synchronization signal level /L'
SL+ (Pedesta) v) In many cases, the stain press-fit is lower, and in the case of white spot B, the normal white stain/l/SL
Many have higher voltage than 2. Therefore, defective pixels can be detected by determining the levels as described above.

Figure 2 is a circuit block diagram for detecting defective pixels.
The signal photoelectrically converted by the D element 1 is amplified by a video amplifier 2, and is input by an encoder 3 to a comparator 4 for TV level detection and a comparator 5 for black defect level detection. If a voltage (A or B in Fig. 1) that seems to be a signal from the defective element is input at this time, it is detected by the comparator 4 or 5, and the period of the signal from the defective element is determined through the OR circuit 6. A correction gate signal G1 to be set is output.

As another circuit for detecting defective elements, FIG. 3 shows a circuit that can easily detect even a halftone defect C without a significant level difference like that shown in FIG. 1A or B. That is, it uses image correlation, and delays the video signal by 4 pixels (61i!!I pixels depending on the color arrangement of the filter) to compare each pixel with the pixels on both sides in the horizontal direction. If the value of the central pixel deviates by a certain amount or more from the values expected from the pixels on both sides, the pixel is determined to be a defective pixel.

In the circuit block diagram of FIG. 3, the video signal v1 from the C and CD elements 1 is input to a 4-bit shift resistor 7 with 2b taps, and the input signal is changed to the output power of the intermediate tap (1) to (2). When the output number is 3, the following relationship holds true for normal output, but this is often the case for defective pixels. Therefore, the video signal v1.

Delayed video signal■2. The window comparator 8 to which V3 is input is connected, and the null level of the comparator 8 is set in advance so that it can be determined as a defective pixel in the case of equation (2). The window comparator 8 outputs the defective pixel signal A from the input signals.

A correction code G2 for setting the periods of B and C is formed and output.

The circuit example in Fig. 3 has a color fill arrangement in the horizontal direction of Fig. 4 (a) Bayer arrangement, Fig. 4 (b) complete green checkered arrangement, and Fig. 4 (c) green checkered field sequential arrangement. Both are color CCs in which the same color is arranged every two pixels.
The image is used for the D element. A color CCD element with a three-color arrangement in the horizontal direction has been proposed as shown in J in Figure 5;
Detection can be made in the same way by constructing a circuit ('f() using one with a t-tap.

Next, a circuit for correcting defective pixels detected as described above will be described.

However, in order to increase the resolution as much as possible with a small number of pixels in a single-plate color CCD element, attempts have been made to create a divine color arrangement as shown in FIG. 4 above. For example, in the Bayer array shown in Fig. 4(a), the G filter letters are arranged in a checkered pattern, so the resolution JIT of the luminance signal is high, and the G signal is divided between adjacent horizontal rows.
When 1jHi Soma Somama is applied, the horizontal resolution is increased to the same extent as in the case of black and white. Furthermore, in order to make effective use of pixels, a complete green checkered arrangement as shown in FIG. 4(1), a green checkered field sequential arrangement as shown in FIG. 4(c), etc. have been proposed. If you look around the entire array, you will see that every other building in the three buildings has the same fill color in the horizontal direction. Therefore, the defect correction data 1 obtained by the detection circuit is used to correct the signal defects. In FIG.
. is immediately applied to the switching circuit 11 and also applied to the 2-bit delay element 10, adding 2 bits to the video signal.
The signal is delayed by bits and output to the switching circuit 11. The switching circuit 11 is normally connected to lead out the video signal vo at the terminal 9 to the output terminal 12, and outputs a signal that does not pass through the delay element. The switching circuit 11 is supplied with a correction gate signal Gl (G2) generated by the defective pixel detection circuit described above, and the connection state is switched by the gate signal Gl, (G2). That is, when the gate signal G r , (G 2) is input, the delay element 10 side is selected and the output terminal 12 receives 2b.
The signal before it is output, and the signal of the defective pixel is 1 bit
A corrected signal is formed by replacing the previous video signal. Figure 4 (a)! In the color fill array shown in l))<c), fills of the same color are arranged every 2 bits in the horizontal direction, so the correction circuit is effective no matter where on the screen there is an element defect. work.

Furthermore, if it is constructed using 4-bit delay elements 140 and 142 with an intermediate tap 13 as shown in FIG. 7, the signal level obtained by the arithmetic mean of the pixels on both sides can be replaced with the defective pixel No. 1H, which is more natural. It is possible to achieve image quality close to that of The correction circuit shown in the above embodiment also uses a delay element of 3 bits or 6 bits even in the case of a three-color arrangement as shown in FIG.
It can be applied by simply changing it to that of it.

Effects> According to the present invention, even if a solid-state imaging device has a defect in a solid-state imaging device, the defective device can be detected and corrected to a level close to a correct signal to form an output signal. No, it is possible to compensate for defects in the solid-state image sensor using a circuit.
The utilization rate of the solid-state image sensor can be increased, and the economical efficiency of applied equipment can be improved.

[Brief explanation of drawings]

Fig. 1 is a diagram showing a video transmission and its defects, Fig. 2 is a grommet diagram showing a defect detection circuit of one embodiment according to the present invention, and Fig. 3 is a diagram showing a defect detection circuit of another embodiment. FIG. 4(a), (b), (c) and FIG. 5 are diagrams showing examples of color fill arrangement, and FIG. 6 is a block diagram showing an example of a correction signal forming circuit according to the present invention. Block Diagram FIG. 7 is a block diagram showing a correction signal forming circuit of another embodiment. 1: CCD, 4.5: Comparator, 7: Delay element, 8: Window comparator, 10: 2-bit delay element, 11 Niswitching circuit, G, , G2: Gate signal for defect correction. Agent: Patent Attorney, Attorney: Aihiko (and 2 others) 2nd BiJ 3111 (o) (b) (C) 4th N1 1 Fig.6

Claims (1)

[Claims] In a solid-state imaging device including a solid-state image sensor (not to mention an image sensor) consisting of one stage of pixels, there is a means for detecting a defective pixel from the arranged pixels, and an output of the detecting means is given. 2. A solid-state imaging device comprising means for supplying an alternative signal while suppressing the output of a signal of one defective pixel to a display device U.2. The solid-state imaging device according to claim 1, characterized in that the defect is detected by comparing the signal level with the signal level of the surrounding element. 2. The same-body imaging device according to claim 1, wherein the detection is performed by comparing with an output level.