JPS631278A - Color solid-state image pickup device - Google Patents

Abstract

PURPOSE:To secure satisfactory color picture quality free from frame afterimage without deteriorating vertical image resolution, by switching the element drive pulses with an electrical switch by using only one color filter for division of one picture element into 2 parts. CONSTITUTION:Photodiodes 1 and 1' give photoelectric conversion to incident light sent from an object via an optical lens and a color filter to obtain the signal charge. This signal charge is read into vertical transfer gates 3-6 forming a vertical transfer register 2 via a signal reading gate 7 when the charge reading pulses are supplied to terminals 8a-8d. Then the signal charge is successively transferred to the vertical direction, i.e., toward a horizontal transfer register 9 by those vertical transfer pulses supplied from terminals 8a-8d. The signal charge is sent successively to a charge detecting part 13 from the register 9 by the horizontal transfer pulses H1 and H2 supplied from terminals 12a and 12b. The part 13 converts the signal charge into the voltage and it through an output terminal 14 as spot sequential picture signals.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color solid-state imaging device, and in particular, it uses a single solid-state imaging device and color filters matched to its light-receiving pixels to perform color imaging using a color-difference sequential method. The present invention provides a color solid-state imaging device that can switch between frame readout and field readout by switching the pulses that drive the solid-state imaging device.

2. Description of the Related Art A method of receiving a color television signal by arranging a color filter corresponding to one solid-state image sensor and its light-receiving pixels will be explained using FIGS. 4 to 6. First, frame readout will be explained. . In FIG. 4, corresponding to the two-dimensionally arranged light-receiving pixels 30, a divided filter consisting of a yellow Ye filter 31 and a magenta Mq filter 32 is arranged at the first light-receiving pixel in the a-line, and the horizontal direction For the next light-receiving pixel, a /An Cy filter 33 and a green G filter 340 dividing filter are arranged, and the color filter rows are arranged alternately in sequence. The first light receiving element has a yellow Ye filter 31 and a green G filter 340.
A dividing filter is arranged, and a cyan Cy filter 33 and a magenta Mq filter 32 are placed at the next light-receiving pixel in the horizontal direction.
The d line has color filter rows arranged sequentially in the same way as the C line, and the e and f lines have color filter rows arranged sequentially in the same way as the a and b lines. Hereinafter, the color filter rows of lines a, b, C, and d are repeated, and the color filter rows are sequentially arranged in all pixels of the solid-state image sensor. Also, in the figure, n
(C) indicates an odd field, and n (C) indicates an even field.

A method of receiving a color television signal using a combination of an image sensor and a color filter configured as described above will be explained with reference to FIGS. 4 and 5.

In FIG. 4, the first field n (c) reads out the photodiode in the horizontal line a. The signal Sn is 5n-J(Ye+Mg)+(Cy+G)((Ye+M
g)-(Cy+G)) sinωt=(2R+3G+
2B)-(G-2R) sinc, +t-=・(i
), and the first field n+1 (c) reads out the photodiode of the horizontal line of C, so the signal Sn
+1 is S n+ 1= ((Ye +G)+(Cy +Mg
) de((Ys+G)-(Cy+Mg)) sinωt=
(2R thousand 3G + 2B) + (G-2B) sin ωt ・
- Similarly to equation (2), the signal Sn' of the second field n()I)' is calculated as follows: Sn=(2R+3G+2B)-(G-
2R) sinω in the second field n+1(H) The signal Sn+1' is Sn+1'= (2R+3G+2B)
+(G-2B) sin ωt.

As is clear from equations (1) and (2), S n +
The low frequency signal component SY of both S n + 1 is 5y
=2R+3G+3B, and the color signal component is (G-2R) sinωt from Sn and (G-2R) from Sn+1.
2B) A color signal component represented by sinωt is obtained.

FIG. 5 shows an outline of a signal processing section for obtaining a color television signal from the output signal of the solid-state image sensor. In FIG. 5, 35 is the solid-state image sensor, 36 is a low-pass filter, 37 is a band-pass filter, 38 is a synchronous detection circuit, 39 is a 1-horizontal period delay circuit, 4o is a 1-horizontal period switch circuit, and 41 is a 1-horizontal period switch circuit. Modulation circuit, 42 is an adder, 4
3 is an output terminal, and 44 is a pulse generator.

Next, the operation will be explained. The signal obtained from the solid-state image sensor 35 is supplied to a low-pass filter 36 to remove harmonic components and separate only low-frequency components to obtain the above-mentioned SY acid component. This low frequency component is treated as a luminance signal and supplied to the adder 42. −
On the other hand, the output signal of the solid-state image sensor 35 is passed through a bandpass filter 3 whose center passband is the repetition frequency of the color filter.
7 and separates the color signal components modulated by the color filter. In other words, from the Sn signal (G-2R
)sinωt from the signal of Sn+, (G
-2B) Separate the components of ginωt. The modulated color signal (color carrier) separated by the bandpass filter is supplied to a synchronous detector 38. The synchronous detector 38 is supplied with an index signal equal to the repetition frequency of the color filter from the pulse generator 44, and the modulated color signal is synchronously detected. The synchronously detected signal becomes a low-frequency color difference signal by removing its harmonic components using a low-pass filter (not shown). f, that is, from the signal Sn (
G-2R) and (G-2B) color difference signals can be obtained from Sn+1.

The color difference signal obtained in this way is transferred to the delay line 3 for one horizontal period.
9, the delayed signal and the non-delayed signal are supplied to the switch circuit 40, and the switch circuit 40 is switched for each horizontal scan using 3'2 pulses of the horizontal scanning e number supplied from the pulse generator. From the output end of 40 (
Two types of color difference signals, G-2R) and (G-2B), are obtained simultaneously. These two types of color difference signals are modulated by a color subcarrier by a modulator 41 to obtain a color signal. This color signal is added to the adder 42.
A color television signal can be obtained from the output terminal 43 by supplying the signal to the output terminal 43 and adding it to the luminance signal described above.

Here, several types of pulses necessary for driving the device are supplied from the pulse generator 44 to the solid-state imaging device 36, and it goes without saying that the driving pulses, index pulses, etc. are in a synchronous relationship.

Next, field reading will be explained. In FIG. 6, corresponding to the light receiving pixels 30 arranged two-dimensionally, in the a line, a yellow Ye filter 31 is applied to the first light receiving pixel, and a cyan AY filter 33 is alternately applied to the next light receiving pixel in the horizontal direction. In the b line, the first light-receiving pixel is a magenta dog filter 32, and the next light-receiving pixel in the horizontal direction is a color filter row in which a green G filter is alternately arranged in sequence. Each odd-numbered horizontal line has the same color filter row as the a-line, and for even-numbered horizontal lines, the b-line color filter and the color filter row that is the reverse of the b-line and color filter rows are alternately arranged. It is located in In the figure, n (c) indicates an odd field and n (c) indicates an even field. In the case of field readout, a scanning method is used in which two adjacent horizontal lines are simultaneously scanned horizontally, and the signal accumulation time to the photodiode is made equal to the vertical scanning time.

A method for obtaining a color television signal from the signal obtained by mixing the signal charges of the photodiodes of two vertically adjacent horizontal lines and then performing horizontal scanning using the combination of the image sensor and color filter configured as described above is described. This will be explained using FIGS. 6 and 6.

In FIG. 6, the first field n (c) is a.

The photodiodes in the horizontal line b are mixed and read out. The signal Sn is Sn=((Ye +Mg)+(Cy+G))+
((Ye+Mg)-(Cy+G))s inωt=
(2R+3G+2B)-(G-2R)s 1nco
t, which is the same as equation (1).

Similarly, the first field n+1 (c) mixes and reads out the photodiodes of the horizontal lines c and d, so the signal Sn+1 is Sn+, = ((Ye+G) + (Cy+Mg)) + ((Y
e+G)-(Cy-+Mq))Iiinωt=(2R+
3G+2B)+(G-2B) sin (,
1t, which is the same as equation (2). Therefore, the signal processing for creating a color television signal may be the same processing as for frame readout, as shown in FIG.

In the case of frame readout, since the signal is created using one horizontal line alone, the vertical resolution has the advantage of being high depending on the number of vertical pixels of the solid-state image sensor and the number of horizontal scanning lines of the television signal. Since the signal accumulation time of the image pickup device photodiode is one frame period, it has the disadvantage that frame afterimage occurs.

In addition, in the case of field readout, since the signal accumulation time of the photodiode is one field, there is an advantage that frame afterimage does not occur, but after mixing the signal charges of the photodiodes of two vertically adjacent horizontal lines, Since horizontal scanning is performed, vertical resolution is reduced.

Problems to be Solved by the Invention As mentioned above, frame readout and field readout have contradictory advantages and disadvantages, and in order to bring out only the advantages of each other, two readout electrical Even if a switch was used, the different color filters shown in FIGS. 4 and 6 had to be replaced, and switching was impossible due to the structure.

In view of the above points, the present invention provides a color solid-state imaging device using a color difference sequential method that can switch between frame readout and field readout using only an electrical switch without replacing color filters. The purpose is to provide.

Means for Solving the Problems In order to solve the above problems, the present invention has two light receiving pixels.
A solid-state image sensor arranged in three dimensions and a two-color color filter divided for one light-receiving pixel of the solid-state image sensor are arranged so that color difference signals are sequentially output, and photoelectric conversion of the solid-state image sensor is performed. A first function in which the signal accumulation time of the photodiode as an element is one frame period, and a signal sequence on one horizontal line of the solid-state image sensor becomes a signal on one horizontal scanning line; The accumulation time is defined as one field period, and in the odd field, the signal on the scanning line is formed by the signal train of the odd (or even) line of the solid-state image sensor, and in the even field, the signal on the scanning line is formed by the signal train of the odd (or even) line of the solid-state image sensor. or a second function of forming a signal on a scanning line using a signal train of an odd-numbered line.

Function: With the above configuration, the present invention basically performs a frame readout method that is advantageous for vertical resolution, even though it is equipped with only one filter, and is particularly suitable for camera photography in a place with sufficient light. In this case, by electrically switching to field readout, it is possible to obtain good color image quality without frame afterimages without deteriorating vertical resolution.

Example Hereinafter, the present invention will be explained based on illustrated embodiments.

FIG. 1 shows an interline charge-coupled solid-state image sensor (hereinafter referred to as "IL-CCDJ") constructed as an embodiment of the present invention.
) is shown.

Reference numerals 1 and 1' denote a large number of photodiodes as photoelectric conversion elements, and 2 a vertical transfer register. The vertical transfer register 2 is composed of vertical transfer gates 3 to 6. 7 is a signal readout gate, isometrically common to vertical transfer gates 3 and 5. 8a to 8d are terminals to which CCDCD drive signals -1 to v4 including charge read pulses and vertical transfer pulses (all described later) are supplied; 9 is a horizontal transfer register; It is configured including game) 10.11. 12a and 12b are horizontal transfer pulses H;

The terminal to which H2 is supplied is a 13-transition charge detection section, and constitutes an output section that converts the transferred signal charge into a signal voltage. This charge detection section 13 is usually composed of a floating diffusion amplifier. 14 is an output terminal. 16 is an overflow drain of the vertical transfer register 30, and 16 is a terminal for supplying a control voltage to the overflow drain 16. 17 is an overflow drain of the vertical transfer register 6, and 18 is a terminal for supplying a control voltage to the overflow drain 17.

19 is a solid-state image sensor.

Photodiodes 1 and 1 are connected to an optical lens,
The incident light that has passed through the color filter shown in FIG. 4 is photoelectrically converted to obtain signal charges. The signal charge obtained by photoelectric conversion is read into the vertical transfer gates 3 to 6 forming the vertical transfer register 2 via the signal readout gate 7 by inputting a charge readout pulse to the terminals 8a to 8d. Thereafter, the data is sequentially transferred in the vertical direction, that is, in the direction of the horizontal transfer register 9, by vertical transfer pulses supplied from the terminals 8a to 8d, and read into the horizontal transfer register 9 every -horizontal line. The signal charges read into the horizontal transfer register 9 are horizontal transfer pulses H1 and H1 supplied from terminals 12a and 12b.
The signal is sequentially transferred to the charge detection section 13 by H2, converted into a voltage by the charge detection section 13, and obtained as a dot-sequential image signal from the output terminal 14. A television signal is obtained by subjecting the dot-sequential image signal thus obtained to the signal processing shown in FIG.

Figures 2 (a), (b), (c), and (cl) are timing charts of CCDCD drive signals -1 to v4 supplied to terminals 8a to ad of IL-CCD 1s during frame readout, and 20 to 23 are photoelectronic timing charts. The signal charges accumulated in the photodiodes 1 and 1 as conversion elements are transferred to the vertical transfer register 2.
24 is a charge read pulse for reading the signal charge into the vertical transfer register 2 to the horizontal transfer register 9.
This is a vertical transfer pulse that sequentially transfers in the direction of . The signal charge accumulated in the photodiode 1 from the charge readout pulse 2o to the charge readout pulse 22 is transferred to the IL-CCD1.
The signal charge accumulated in the photodiode 1 from the charge readout pulse 22 to the charge readout pulse 23 becomes the first field signal based on the operation of XL-CC.
An image signal of the second field is generated based on the operation of D19. At this time, the terminal voltage 16.18 is set so that the overflow drain 15.17 operates only when charge overflows.

Next, in FIG. 6, the IL when the frame readout field readout switch 46 is set to the field readout side.
-CC supplied to terminals 8 a to 8 d of CCD 19
The DCD drive signal -1 to v4 timing chart is shown in Figure 3 (
Shown in a), (b), (C), and (d). 2
5 to 28 are charge read pulses for reading the signal charges accumulated in the photodiodes 1 and 1 as photoelectric conversion elements into the vertical transfer register 2; 29 is a charge read pulse for reading the signal charges read into the vertical transfer register 2 into the horizontal transfer register 9; This is a vertical transfer pulse that sequentially transfers data in the direction of . The signal charge accumulated in the photodiode 1 from the charge readout pulse 26 to the charge readout pulse 26 becomes the signal 4 of the second field based on the operation of the IL-CCD 19, and the signal charge accumulated in the photodiode 1 from the charge readout pulse 26 to the charge readout pulse 27 becomes the signal charge 4 of the second field. During this period, the signal charge accumulated in photodiode 1 is transferred to IL-CCD.
The signal (B) of the first field is generated based on the operation of step 19. The signal (q) accumulated in the photodiode 1 between the charge readout pulse 26 and the charge readout pulse 25 and the signal p accumulated in the photodiode 1 between the charge readout pulse 27 and the charge readout pulse 28 are , the signal (q
is mixed with the signal (to), and the signal port is mixed with the signal ■.Since the color difference sequential output cannot be obtained by the signal processing shown in FIG. Sweeped out to the overflow drain 16, the signal q is
A control signal is given to the terminal 1e, and the overflow drain 1
Sweep out at 7. A video signal is formed by the signal (to) and the signal (to), and since the photodiode 1 is in field readout at this time, no frame afterimage occurs.

As described in detail, the color solid-state imaging device of the present invention uses only one color filter that divides each pixel into two, and can switch element drive pulses using an electrical switch, and is basically capable of switching between frames. When operating the camera in readout mode and taking pictures in a place with sufficient light, switching to field readout mode will not degrade the vertical resolution and eliminate frame afterimages, so depending on the situation, This has the excellent effect of being able to obtain the best color image quality.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an IL-COD according to an embodiment of the present invention, FIG. 2 is a timing chart of a COD drive signal during frame readout of this embodiment, and FIG. 3 is an OCD during field readout of this embodiment. Timing chart of drive signals, Figure 4 is a layout diagram of color filters used for frame readout, Figure 6 is a block diagram of a signal processing unit that converts the signal obtained from the solid-state image sensor into a color television signal, Figure 6 1 is a layout diagram of color filters used in conventional field readout. 1.1...Photodiode, 2...
Vertical transfer register, 9...Horizontal transfer register,
15.18...to overflow drain, 19...
...IL-CCD 12Q~23.26~28
...Charge readout pulse, 30 ... Light receiving pixel, 44 ... Pulse generator, 45 ... Frame readout field readout switch 0

Claims (1)

[Claims] A solid-state image sensor in which light-receiving pixels are arranged two-dimensionally, and a two-color color filter divided for one light-receiving pixel of the solid-state image sensor are arranged so that color difference signals are sequentially output, a first function in which a signal accumulation time of a photodiode as a photoelectric conversion element of the element is set as one frame period, and a signal sequence on one horizontal line of the solid-state image sensor becomes a signal on one horizontal scanning line; The signal accumulation time of the photodiode is set as one field period, and in the odd field, the signal on the scanning line is formed by the signal train of the odd (or even) line of the solid-state imaging device, and in the even field, the solid-state imaging 1. A color solid-state imaging device, characterized in that the color solid-state imaging device has a configuration in which a second function of forming a signal on a scanning line is electrically switched between a signal train of an even-numbered (or an odd-numbered) line of an element and a second function of forming a signal on a scanning line.