JPS59103486A - Solid-state color image pickup device - Google Patents

Abstract

PURPOSE:To improve the horizontal resolution by arranging the center of sensitivity of picture elements so as to be interleaved in adjacent horizontal picture element trains in a solid-state image pickup device for TV camera and scanning and adding two adjacent horizontal picture elements at the same time, allowing to eliminate the effect of the vertical transfer efficiency on the picture quality. CONSTITUTION:A signal charge is stored in a photo didoe 2(2a, 2b-) by an incident light from an object during one vertical period and a vertical scanning pulse generated from a vertical shift register 5 is applied to a gate of a vertical switch MOS-FET4 to transfer the signal charge onto a signal line 3 and then to a transfer capacitive element 8, the charge is transferred to a horizontal CCD10 and read out to a signal output section 11 at one horizontal scanning period, and two horizontal lines (a and b, c and d etc.) are read out at the same time during one horizontal scanning period. Cyan, yellow and magenta filters 12-14 are sequentially and repetitively arranged corresponding to each photo diode 2, the same chroma signal is obtained at each vertical line and a luminance signal is obtained by reading and adding plural adjacent horizontal lines at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a solid-state color imaging device for a television camera that uses a single solid-state imaging device and a color filter disposed in front of the solid-state imaging device.

Conventional Structures and Problems Various types of single-chip color solid-state imaging devices have been proposed that use a single solid-state imaging device to obtain color images.

As is well known, solid-state imaging devices include charge transfer devices of the C0D (charge coupled device) type or BBD.
(bucket top prigate de/tice) type, MO', S type of x-Y address element, among these, MO8
type solid-state image sensor uses vertical and horizontal shift registers to
Since signals are read out by sequentially switching O8 type transistors, spike noise occurs especially due to switching pulses during horizontal scanning.Moreover, as the number of pixels increases, this spike noise increases with respect to the signal and reduces the S/N ratio of the image quality. is restricted.

However, since X-Y addressing type solid-state image sensors read out signal charges from pixels by addressing them, there is no crosstalk between adjacent signal charges in the vertical direction, resulting in a mosaic pattern as shown in Figure 1. It is suitable for a color one-sided method that uses a color filter and uses vertical correlation to obtain a color signal. In FIG. 1, the part indicated by the dotted line is the photodiode of the light receiving section, and the solid line indicates the color filter/element.

In addition, COD uses a frame transfer method in which the signal charge of the light receiving section is transferred to the storage section at high speed for each frame and sequentially read out from the storage section through a horizontal transfer stage, and the signal charge of the photodiode is transferred every vertical line. There is an interline method in which signal charges are read out onto an independent vertical transfer line, transferred to a horizontal transfer stage every horizontal scanning period, and sequentially taken out as a serial signal from this horizontal transfer stage.In the case of the former frame transfer method, Since the channel stopper exists only in the vertical direction, crosstalk of signal charges occurs in the adjacent vertical direction, and the color one-way method that uses vertical correlation to separate color signals is impossible, as shown in Figure 2. It is necessary to use all of the R, G, and B striped color filters shown in the figure to create a color-only system that does not cause color mixing even if there is crosstalk. However, this method has the disadvantage that a wide band of luminance signals cannot be obtained because the color filters are repeated every three.

In addition, in the case of the interline method, since the photodiodes that are the light receiving sections are located separately, it is also possible to use the mosaic color filter shown in Figure 1.
Since the transfer efficiency of the vertical transfer stage was not 100%, color mixing occurred due to components left behind.

OBJECTS OF THE INVENTION The present invention provides a color solid-state imaging device that eliminates the influence of non-transfer efficiency on image quality in the vertical transfer stage of a solid-state imaging device, and that has a high light utilization rate without causing a decrease in horizontal resolution relative to the number of pixels in the horizontal direction. The purpose is to

Structure of the Invention The present invention has pixels that are arranged so that the imaging center of the pixel is interleaved in adjacent horizontal pixel columns, and a scanning mechanism that simultaneously scans two adjacent horizontal pixel columns. For each pixel on this solid-state image sensor, a cyan filter (filter that blocks red light) that transmits blue light and green light and a yellow filter (filter that blocks red light) that transmits green light and red light are used. A filter that blocks light) and a magenta filter that transmits red and blue light (
Filters of three colors (filters that block green light) are arranged repeatedly in the horizontal direction, and filters of the same color on adjacent horizontal pixel columns are arranged so as to be interleaved.

A luminance signal is obtained by applying low-frequency waves to the signals of the two horizontal pixel rows output from the element configured in this way, and the spatially modulated color signal contained in the previously outputted signal is obtained. Detect and obtain color difference signals.

A composite color signal is created using this luminance signal and color difference signal.

DESCRIPTION OF THE EMBODIMENTS FIG. 3 shows the structure of a six-beam priming water transfer type solid-state imaging device, which is one of the components of a color solid-state imaging device according to an embodiment of the present invention. In the figure, 1 is a solid-state image sensor, 2,
(2a, 2b, 2c...) are photodiodes which are light receiving sections. Normally this photodiode? is formed by a PN junction, and the centers of the photodiodes 2 are arranged in a staggered manner so as to be interleaved with respect to the adjacent vertical direction.

3, (3a, 3b, 3C...) are vertical signal lines, and the connection relationship between the photodiode 2 and this vertical signal line 3 is as shown in FIG. Each signal line is connected to alternate vertical signal lines 3. That is, the photodiode 2a of the first horizontal line in FIG. 3 is connected to the vertical signal line 3a, the photodiode 2b of the second horizontal line is connected to the vertical signal line 3b, and so on. ．． (4a, 4
b, 4c...).

5 is a vertical shift register, and this vertical shift register receives vertical scanning pulse φsP and crossf pulse φVl''V.
The output terminal of each stage of the vertical shift register 7 pages 6 is connected to the vertical address lines 6, (6a
, eb, ec...) via MOS-F
It is commonly connected to the gate of one horizontal line of ET4.

Also, one end of the vertical signal line 3 is a transfer 03-FET7,
(7a, 7b, 7c-...-, 7a',
7b', 7c'...-) are connected to the sources. The gates of these MOS-FETs 7 are connected in common.
, becomes the transfer node input line (φTG). Mo5 for transfer
- Transfer capacitive elements 8, (8a, 8b, 8c) whose other ends are common to form a transfer pulse input line (φTC) are installed in the drain part of the FET7.
, 8a', 8b', 8c'...) are not connected. Here, the capacitance of the transfer capacitive element 8 is sufficiently smaller than the capacitance of the vertical signal line 3.

9. Transfer gate adjacent to transfer capacitive element 8). '(9a,
9 b, 9 C----, 9a', 9b',
9c'...) are provided, and their gates are commonly connected to form a transfer gate input line (φTB). Adjacent to this transfer gate 9 is a charge-coupled horizontal shift register (hereinafter abbreviated as horizontal CCD) 10. (10
a, 1oa') are arranged, and one end in the horizontal direction is connected to the signal output section 11° (11a, 11b').

For details of the priming water transfer type solid-state image sensor, please refer to the patent application filed in 1973
Since it is described in No. 135590, a simple explanation will be given here.

During one vertical period, signal charges are accumulated in the photodiode 2 due to the incident light from the subject. The vertical scanning pulse generated from the vertical shift register 6 is sent to the vertical switch MO.
In addition to the gate of the 8-FET 4, the signal charges accumulated in the photodiode 2 are transferred onto the vertical signal line 3. φT in the letter
G, φTCvC voltage is applied and transferred to the vertical signal line 3.
The signal charge is transferred to the transfer capacitive element 8. The signal charge transferred to the transfer capacitive element 8 is transferred to the horizontal CCD 1o by applying a voltage to the transfer gate 9.

Then, the signal charge transferred to the horizontal CCD 10 is transferred to the signal output section 1 during one horizontal scanning period by an appropriate transfer lock.
Transferred to 1 and read out. The clock frequency of this horizontal transfer is determined by the number of photodiodes 2 arranged in one horizontal line, and in the case of 384 photodiodes 2, it is approximately 7.2 times.

The solid-state image sensing device, which is one of the components of this device, is based on the above-mentioned operating principle, and is further characterized in that signals of a plurality of horizontal lines are simultaneously read out during one horizontal scanning period.

That is, in the nHth horizontal scan of the first field, the signals of the two horizontal lines a and b shown in FIG. In the nH-th horizontal scan of the second field, the signals of the two horizontal lines b and C are read out, and the signals of the two horizontal lines b and C are read out in the (n+
In the horizontal scanning of IH), the signals of d and the next horizontal line (not shown) are read out simultaneously.

FIG. 4 is a diagram showing a color filter, which is one of the constituent elements of this device.

In FIG. 4, the rectangle indicated by a dotted line represents the photodiode 2. shown in FIG. (2a, 2b, 2c...) are schematically shown, and corresponding to this photodiode 2, a cyan (CY) filter 12, a yellow (Ye) filter 13, and a magenta (M) filter 14 are installed. They are arranged repeatedly in sequence.

With such an array configuration of the photodiode 2 and the color filter, in the nH-th horizontal scan, the horizontal 〇CD11
From the output terminal of a, there are photodiodes (2a, 2
a', 2a ”...) output signal, that is, C
A signal spatially modulated by the Y, M, Ye filter is obtained, and from the output terminal of the horizontal CD11 a', a photodiode (2b, 2b', 2b''...
. ), that is, a signal spatially modulated by the Ye, Cy, and M filters.

When the configuration of the photodiode and color filter shown in FIG. 4 is applied to the solid-state image sensor shown in FIG. is the horizontal CC via the priming transfer stage.
The signals are transferred to D1oa and D1oa' at the same time, but the two horizontal CODs are operated with a phase difference. That is, the output signals of the horizontal COD appear point-sequentially at the output terminals, but the output signal group of the horizontal CD10a' appears at the output terminals of the horizontal CCD.
By making the phase of the transfer pulse applied to the horizontal COD different so that the phase difference between the output signal group 10a and the output signal group 1800 is obtained, the horizontal COD? Horizontal CCD10 when activated
FIG. 6 shows the relative phases and spectral characteristics of the output signals of a and 10a'.

In FIG. 5, A is the horizontal CG D10a, that is, photodiodes 2a, 2a', 2a''・old・
B is a schematic representation of the output signal of the horizontal CCD 1ob, that is, the photodiodes 2b, 2b', 2b''--group.

In Fig. 5, the time interval between signals is '4 (f: horizontal transfer lock frequency), and by the method described above, A
, E, there is a 180'V phase difference between the signals. Also, if the red signal is R1, the green signal is G, and the green signal is B, then Cy = (G + B), M = (R + B), Ye = (R +
G), the spectral characteristics of the output signals from each photodiode are as shown in FIGS. 6A and 6B.

FIGS. 6A and 6B are diagrams showing spectral distributions of the signal sequences shown in FIGS. 6A and 6B. The frequency f is the horizontal transfer lock frequency, and color carriers due to the modulated color signal are generated near the frequency gf. Further, the phases of the color carriers at this time differ by 1800 as shown in FIGS. 7A and 7B.

Therefore, by adding the output signals of the horizontal CCDs 10a and 10a'O, the color carriers existing near the frequency of if are canceled out. By further adding the signal as shown in Figure 8, the number of photodiodes in the horizontal direction is isometrically doubled, so the sampling frequency in the horizontal direction is essentially doubled. be equal. FIG. 9 shows the spectral distribution of the signal train shown in FIG.

As is clear from FIGS. 8 and 9, the horizontal CCD 10
If the output signals of a and 10a/ are added, the color carrier near Kf of the horizontal transfer lock frequency is canceled out, and the color carrier of the modulated color signal is generated near % of the horizontal transfer lock frequency f, so the actual The band of the luminance signal is limited to %f due to the color carrier. However, this value of %f is different from the conventional luminance signal band hf.
Since the horizontal resolution is twice that of the previous one, the horizontal resolution is significantly improved.
3.

Ru.

The above explanation is for the nHth in FIG. 4, that is, a,
I explained about the horizontal line b, but the (n+1)th line
The same holds true for the H-th horizontal lines, ie, c and d. Furthermore, the same holds true for the fourth horizontal line of the second field, i.e., c.

Next, the electrical signal processing circuit of the solid-state color imaging device will be described with reference to FIG. In FIG. 10, reference numeral 16 denotes a solid-state image sensor, which has the structure described above and has a color filter bonded to it. Reference numeral 16 denotes a synchronizing signal generator, which conveniently uses a frequency four times as high as 3.58M as the original oscillation frequency. This synchronizing signal generator 16 generates pulses φsP, φ
Drive signals for the solid-state image sensor 15 such as V11φV2°φTG=φTc and φTB are generated by the drive circuit 17 and supplied to the solid-state image sensor 16. The two output signals of the solid-state image sensor 16 are supplied to an adder 18 and summed, and the output signal of the adder is supplied to a low-pass filter 19 with a pole frequency of %f to remove unnecessary high-frequency components. After that, it is supplied to En 147, -] and Coorg 20.

On the other hand, regarding the color signal, the output signal of the adder 18 is supplied to a bandpass filter 21 with a center frequency of %f, and a color carrier signal is extracted. The obtained refined color carrier signal is synchronously detected by the synchronous detectors 22 and 23 using different synchronous detection reference signals of 9o phase, and unnecessary high-frequency components are removed by the low-pass filters 24 and 25, and then the encoder 2゜ to obtain a color television signal.

Here, the frequency of the reference signal supplied to the synchronous detectors 22 and 23 is % times the horizontal transfer lock frequency f,
It has a synchronous relationship with the horizontal transfer lock. 26 is a phase shifter for shifting the phase of the reference signal for synchronous detection obtained from the synchronous signal generator by 90 degrees so that the reference signal supplied to the synchronous detectors 22 and 23 has a phase difference of 90 degrees. .

The output signal of the bandpass filter shown in FIG. 10 is S.

As it is clear from Figure 8, the following margins 15° K1〈1. ni2ku1　ω−2π・if becomes.

This signal is converted into CQS2π・−ft and sin 2π・−f
If the high-frequency components are removed by synchronous detection with the reference signal 3 of t, low-pass-M)
A color difference signal is obtained. By modulating these two color difference signals with a color subcarrier and adding the luminance signal, a standard composite color television signal can be obtained.

In the above embodiments, the color filters are arranged in a striped pattern as shown in FIG. 4, but depending on the shape of the photodiode, they can also be arranged in a mosaic pattern as shown in FIG. 11. Furthermore, in the signal processing of the embodiment, color signals were obtained by synchronous detection, but the method of sampling and separating signals through three different filters and the configuration of independently outputting three signals from a solid-state image sensor are also similar. possible.

Effects of the Invention As described above, according to the solid-state color imaging device of the present invention, it is possible to eliminate the influence of vertical transfer efficiency on image quality.
Moreover, the horizontal resolution can be improved by a total of four times compared to the conventional method. Further, since the complementary color combination filter is used, a color solid-state imaging device with a higher light utilization rate can be obtained compared to a system using primary color filters.

[Brief explanation of the drawing]

1 and 2 are front views for explaining color filters in a conventional solid-state color imaging device, and FIG. 3 shows a plurality of horizontal filters used in a solid-state color imaging device according to an embodiment of the present invention. A circuit diagram of a solid-state image sensor configured to simultaneously read out line signals; FIG. 4 is a front view showing the relationship between color filters and photodiodes used in the device; FIG. 6A
, B is a schematic diagram showing refined output signals obtained by horizontal scanning of lines a and b in FIG. 4, FIGS. 6A and B are spectral diagrams of each signal in FIG. 6, and FIG. 7A, B is a vector diagram showing the phase of the color carrier of each signal in Fig. 517;
FIG. 8 is a schematic diagram showing a signal obtained by adding each signal in FIG. 5,
FIG. 9 is a spectrum diagram of the signal shown in FIG. 8, FIG. 10 is a block diagram showing the overall electrical circuit configuration of the same device, and FIG. 11 is a front view showing another example of a color filter that can be used in the same device. be. 1... Solid-state image sensor, 2. (2a, 2b, 2c
......)...Photodiode, 3. C
3a, '3b, 3a...)... Vertical signal line, ' * (4a @ 4b, 4a...)
...MOS-FET, 5... Vertical shift register, 6. (6a, 6b, 6c...)・
...Vertical address line, 7. (Complete a, 7b, ?c・
・・・・・・． 7a', 7b', 7c', , -...-)
・----・MO8-Fl for transfer! :T. 8, (8a, sb, 8cm river, Ba', Bb
', 8c'・-・・・・・・transfer capacitive element,
9e (s a * s bl sa *・・・・・・
, 9a', 9b', 9c'...)...
Transfer gate, IQ. (10a, 10a') ---Horizontal CCD, 1
1, (11a. 11a')...Signal output section, 12...
Cyan filter, 13...Yellow filter, 14.
... Magenta filter, 16 ... Solid-state image sensor, 16 ... Synchronization signal 18. Generator, 17... Drive circuit, 18...
Adder, 19...Low pass filter, 2o...
...Encoder, 21 band pass filter, 22,
23... Synchronous detector, 24.25...
Low-pass filter, 26...900 phase shifter. Name of agent: Patent attorney Toshio Nakao and one other person
ωmin min′″″″
``Extend゛'

Claims (1)

[Claims] A first color filter element that transmits blue light and green light, a second color filter element that transmits red light and blue light, and a third color filter element that transmits green light and red light are arranged horizontally. The color filters are arranged sequentially, and the color components spatially modulated by the color filter elements are inverted by 1800 for each horizontal line, and each vertical signal is obtained from the light receiving section corresponding to each color filter element. The signal line has a solid-state image sensor that obtains the same color signal and simultaneously reads out the signals of the light-receiving elements of adjacent horizontal lines on multiple signal lines, and by adding the signals read out at the same time. A solid-state color imaging device characterized in that it obtains a luminance signal.