JPS6031385A - Single board color camera - Google Patents

Abstract

PURPOSE:To compensate electrically the drift of transfer efficiency by providing a sample hold circuit between an image pickup element and an amplifier. CONSTITUTION:The sample hold circuits 14, 15 are provided between the image pickup element 1 and the amplifiers 2, 3. The sampling position of the circuits 14, 15 is selected as a position SP in Fig. A. Thus, the output waveform of the circuits 14, 15 is as shown in Fig. B. In Fig. A, b1 is the 1st read signal and b2 is a read signal close to the end. Further, b1' and b2' are the output signals of the circuits 14, 15, and especially the b2' is a signal adding the signal and an idle bit signal [leak signal (c)] so as to correct the reduction in the read signal of the image pickup element due to incomplete transfer during a horizontal period.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a single-chip color camera using a solid-state image sensor.

Conventional configurations and their problems Regarding this type of camera, for example, NATION
KCHNIC person 1. RKPORT VOL, 28.
It is introduced in detail on pages 33 to 42 of No. 2 (APR01982). The configuration of the CPD image sensor 1 will be explained below using FIG. 1. The CPD image sensor 1 has two output terminals tj
, t2, and the relationship with the pixels is such that 1 is read into the upper and lower horizontal registers u, c c n every other pixel in the horizontal direction. Here, Cy+Ye+
Mq+σ is a color filter arranged in the light receiving section of the GPD image sensor 1. Therefore, two output terminals 1+.

From t2, the amplified signals are added through amplifiers 2 and 3, respectively.
6 to obtain the luminance signal. In addition, the color difference signal is
two output terminals t1. From t2, the signals passed through amplifiers 2 and 3 are input to LPF 6 with a J-off frequency of 500 kHz.
．． By subtracting with subtractor 8 through 7, Cy-Y
The color difference signals of e and Mq-G are sequentially banded every horizontal period.These signals are basically connected to the IH period delay line (I
IH5W circuit 1 composed of Sui Nochi with HDL) 9
o, and are separated into Gy-Yem L and Mq-G color difference signals, which are then sent to N by the encoder 11 together with the luminance signal.
It is converted into a TSC signal. Here, 12 is a luminance signal correction circuit, 13 is a white balance correction circuit, FDA is a reading portion of the horizontal register JCCD, and CPT is a priming transfer portion.

In this way, for each pixel, the upper and lower horizontal registers H, COD
When the transfer efficiency of the horizontal registers H, GCD is incomplete, that is, when the transfer efficiency is not 100%, a signal leaks to the empty bits. The amount increases as it approaches the final stage of the IH period.

For example, project a uniform white pattern, horizontally 7 stars H, CO
The output signal when the reading peak part FDA on the output side of D is driven with a reset pulse for each bit is as shown in FIG. In the figure, a is a reset noise, b is a signal valve, and C is a leakage signal to an empty bit.

Therefore, luminance shading occurs in the luminance signal. Furthermore, when the transfer efficiency of the upper and lower horizontal registers H9COD is the same, the color signal amounts will be different on the left and right sides of the screen, and when they are different, color shading will occur.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks and provides a single-chip color camera that electrically compensates for drift in transfer efficiency.

Structure of the Invention In order to achieve the above object, the present invention provides a sample and hold circuit between an image sensor and an amplifier.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will now be described with reference to FIG. In the figure, 1, 2.3 corresponds to 1.2.3 in FIG. Therefore, the output terminals tj and t2 output a signal with a leakage C in the empty bits as in the conventional example, as shown in FIG. 4(a). 14 and 15 are sample and hold circuits. Here, the sampling position of the hold circuits 14 and 15 is set to the sp position shown in 4th v (a). Therefore, with respect to the output of the image sensor 1 shown in FIG.
It will look like figure (b). Here sample hold circuit 1
Figure 4 (
A) and (o) will be mainly explained. bl is the first read signal, and bl is the near final read signal. Also b
l.

bl is the output signal of the sample-and-hold circuit 14.15. In particular, bl is a signal obtained by adding the main signal and an empty bit signal (leakage signal), and corrects the drop in the readout signal due to incomplete transfer of the image sensor 1 during the horizontal period. can.

Effects of the Invention As explained above with reference to the embodiments, according to the present invention, the image sensor can be made into a form of perfect transfer, so good image quality can be obtained, while the amplitude of the transfer pulse of the image sensor can be adjusted by one phase, etc. The degree of freedom increases.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional single-chip color camera, Fig. 2 is an output waveform diagram of an image sensor, Fig. 3 is a block diagram of main parts of a single-chip color camera according to an embodiment of the present invention, and Fig. 4 is a block diagram of a conventional single-chip color camera. It is an output waveform diagram. 1... Image sensor, 2, 3... Magnifier,
14. IEy...Sample fist hold circuit.

Claims (2)

[Claims] (1) An image sensor in which a color filter is arranged on a light receiving part and a signal from the light receiving part is read every other bit in a horizontal scanning direction into a different horizontal register for every other pixel; A single-chip color camera consisting of a sample and hold circuit. (2) A single-chip color camera according to claim 1, wherein the sample-and-hold circuit is connected to each of the two output terminals of the image sensor and amplifies the output thereof.