JPS63199590A - Color solid-state image pickup device - Google Patents

Abstract

PURPOSE:To improve resolution and to improve optical utilization efficiency by setting eight picture elements, two in a horizontal direction and four in a vertical direction, as one unit, for the array pattern of color filters provided in front of the solid-state image pickup element, and setting respective color filters constituting one unit to the specific color filters. CONSTITUTION:If the array pattern 1a of the mosaic like filter provided in front of the solid-state image pickup device 2 is constituted by the repeating pattern in which eight picture elements, two in the horizontal direction and four in the vertical direction, are set to be one unit, and the position of the array pattern of one unit is shown as Cij ((i) is the position in the horizontal direction and (j) is that in the vertical direction), a first color filter transmitting all color light beams is arranged in C14, C22, a second color filter transmitting only the color light beams of selected spectrum area in C12, C24, a third filter transmitting either of a couple of complementary color light beams respectively having the color light beams transmitting the second color filter, and having respectively different color light beams in C11, C23, and a fourth color filter transmitting the other complementary color beam in C13, C21.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a color solid-state imaging device equipped with a solid-state imaging device in which a plurality of light-receiving elements are arranged both horizontally and vertically. This relates to the arrangement of mosaic color filters arranged in front of the .

[Prior Art] FIG. 17 shows an array configuration of a mosaic color filter (hereinafter referred to as "filter") (1) of a conventional color solid-state imaging device disclosed in, for example, Japanese Patent Laid-Open No. 51-112228. In this figure, green light transmitting filters (hereinafter referred to as "G filters") are arranged in a checkered pattern every other in both horizontal and vertical directions, and red light transmitting filters (hereinafter referred to as "G filters")
below.

"R filter") and blue light transmitting filter (hereinafter "B filter") are arranged every other row.
It is arranged horizontally between the G filters.

The R-G-B filter that constitutes this filter (1) is:
It is arranged at a position corresponding to each of the light receiving elements arranged in the horizontal and vertical directions, and samples the incident image light with the red, green, and blue color components using the filter (1). The light receiving element is configured to detect one type of color light component.

FIG. 18 is a characteristic diagram of the conventional filter (1) when color light carriers, which will be explained later, are expressed in two-dimensional frequency planes.

[Problems to be Solved by the Invention] In the conventional color solid-state imaging device equipped with the filter (1) configured as described above, since the G filters are arranged in a checkered pattern, The directional resolution is low, and the vertical spacing of the R and B filters is half that of the G filter, so
The resolution for the red light image and the blue light image is also lower than the resolution for the green light image, resulting in a reduction in resolution, which poses a problem in that moiré fringes are likely to occur.

In addition, since only one type of color light component is incident on each light-receiving element, the amount of light that actually enters each light-receiving element out of the amount of light incident from the optical system is small, resulting in poor light utilization.
There was a problem in that the imaging device had low sensitivity.

This invention was made to solve the above-mentioned problems, and aims to provide a color solid-state imaging device with good resolution, less occurrence of moiré, and high sensitivity.

[Means for Solving the Problems] A color solid-state imaging device according to the present invention includes a solid-state imaging device composed of light receiving elements arranged both horizontally and vertically, and a solid-state imaging device arranged in front of the solid-state imaging device. a mosaic color filter, and a signal synthesis processing means for synthesizing the output signal of the solid-state image sensor into a video signal of a predetermined format, and the arrangement pattern of the mosaic color filter is 2 pixels in the horizontal direction and 2 pixels in the vertical direction. When the direction is composed of a repeating pattern in which one unit is eight 4-pixel pixels, and the position of one unit of array pattern is expressed as C11 (i is the horizontal position, j is the vertical position), C14, C22 is a first color filter that transmits all color light, C12°C24 is a second color filter that transmits only color light in a selected spectral region, and C11 and C23 are each the above-mentioned second color filter. CI3 * C21 includes a third filter that transmits one of a pair of complementary color lights that transmits color light that is different from each other, and a fourth filter that transmits the other complementary color light. It is characterized by the fact that filters are arranged respectively.

[Function] In the mosaic color filter of the present invention, the first color filter transmits all color light, the second color filter transmits only color light in a specified spectral region, and the third and fourth color filters transmit all color light. each includes color light that passes through the second color filter, and transmits either one of a pair of complementary color light that includes mutually different color light.

Therefore, the colored light that passes through the second color filter passes through all the other color filters and is detected by all the pixels (light receiving elements). Further, the colored light that does not pass through the second color filter passes through either the first and third color filters or a combination of the first and fourth color filters, and is detected by the corresponding light receiving element. Therefore, even for colored light that does not pass through the second color filter, it is equivalent to being detected by all pixels in both the horizontal and vertical directions.
As the resolution improves, the efficiency of light utilization also increases, so the sensitivity also improves.

[Embodiments of the invention] An embodiment of this invention will be described below.

FIG. 1 is a block circuit diagram of this embodiment.

In the figure, (18) is an optical system, (1a) is a mosaic color filter (hereinafter referred to as "filter"), (2)
are solid-state image sensors, (3), (4), (5)
is an IH delay element that delays the signal by l horizontal scanning time,
(8).

(7), (8) are arithmetic units, (9), (10
) is a bypass filter, (11) is a low-pass filter,
(12), (13) are modulators, (14), (1
5) is an interlocking switch circuit, (!8) is an encoder that outputs a video signal of a predetermined television system, and (17)
is the output terminal.

FIG. 2 is a diagram showing the arrangement pattern of the filter (1a),
8 with 2 pixels in the horizontal direction and 4 pixels in the vertical direction surrounded by a solid line
An array pattern is formed in which the arrays of two color filters are arranged as one unit and are repeatedly arranged in both the horizontal and vertical directions. The effect of this arrangement pattern will be explained below with reference to FIGS. 3 to 5.

FIG. 3 is a diagram showing one unit of the array pattern shown in FIG. 2.

First of all, let's explain how excellent the color filter array shown in Figure 3 is.The light that passes through the 0-color filter is photoelectrically converted by a light receiving element, and an electrical signal is output according to the amount of light. Therefore, the incident light image is two-dimensionally sampled by this array of color filters.

Ye filter transmits red light component and green light component, and C
Since the V filter transmits blue light components and green light components,
The green light component is sampled by the color filter of the incident light.
When looking at the red light component and the blue light component, in Figure 0, which looks like Figure 4, G.

R and B indicate that green, red, and blue light components are sampled, respectively, and 0 indicates that they are not sampled.

In this way, by obtaining the Fourier transform of the sampling performed on the vertical plane (xy plane), we can obtain the two-dimensional frequency plane (fx fy plane) in the horizontal and vertical directions.
In Figure 5, the arrows represent the carriers of each color light component, and the length of the arrow represents the size of the carrier.

The orientation indicates the phase relationship. The carrier G of green light (hereinafter referred to as "G carrier") is 0 < f X ≦ π,
For 0≦f, ≦π, Cfx, fv )=(0,0
), and it can be seen that it has the highest resolution. Red light carrier R (hereinafter referred to as “R carrier”)
).

Carrier B of blue light (hereinafter referred to as "B carrier") is fx on the axis of the ring, and there are no carriers on the axis other than 0%2π, and the horizontal and vertical resolution is as high as that of green light. have And also for the diagonal direction (fx
, fy ) = Since there is a sufficient distance from (0, 0), there is no significant deterioration in resolution compared to the horizontal and vertical directions.The conventional mosaic color filter (1) shown in Fig. 17
This becomes clearer when compared with FIG. 18, which shows the arrangement of optical carriers of each color.

The processing content of color solid-state imaging devices differs depending on the system used, but in this embodiment, interlaced scanning is performed, and the solid-state imaging device (2) independently processes l-frame signals in two rows at a time. It shall be read within the field.

Next, the operation of this embodiment will be explained.

Figure 6 is a diagram showing the signals of each part in the field,
In the m-th scanning line, the signals of the pixels in the n-th and n+1-th rows are simultaneously read out from the signal line S2*St. At this time, the output of the arithmetic unit (6) is a blue light component signal (hereinafter referred to as "B signal") whose sign is inverted for each pixel, as shown in FIG. The frequency at which the sign is reversed for each pixel corresponds to the π frequency. Therefore, the bypass filter (9) following the arithmetic unit (6) is π
Using the frequency with which the response is maximum, the B signal that has passed through this bypass filter (9) is sent to the modulator (12).
) and becomes a baseband B signal.

Next, looking at the output of the arithmetic unit (7), we see that the red light component signal (hereinafter referred to as the "R signal") has its sign reversed for each pixel, similar to the case of the B signal above. is modulated at the π frequency.

Therefore, the bypass filter (10) following the arithmetic unit (7)
) is used that has a maximum response at the π frequency, and the R signal that has passed through this bypass filter (lO) is demodulated by the modulator (13) and becomes a baseband R signal.

Next, the output of the arithmetic unit (8) is 2G+R and 2G+R+2
B appears alternately, and this signal is then smoothed by a unified low-pass filter (11) to form 2G+B+R.
It becomes a signal.

The two switch circuits (la) and (t5) are switched in conjunction with each other for each field, and if the state shown in FIG. 1 corresponds to the field in FIG. ) provides the output of the modulator (12), ie, the B signal, and the other switch circuit (15) provides the output of the modulator (13), ie, the R signal. Then, the encoder (18) outputs the video signal in a predetermined format from the output terminal (17).

FIG. 7 is a chart showing the signals of each part in the other field. In this field, when the scanning line is m-th, the signals of the pixels in the (n-1)th and n-th rows are simultaneously output from the S2*S1 signal line. The arithmetic unit (8) outputs an R signal modulated at a π frequency, the arithmetic unit (7) outputs a B signal modulated at a π frequency, and the arithmetic unit (8) outputs 2G+B and 2G+B+2.
R is output alternately. The modulator (12) outputs a baseband R signal, and the modulator (13) outputs a baseband B signal. Two switch circuits (1
4) and (15) are switched from the state shown in FIG.
), ie, the B signal, is obtained, and the output of the modulator (12), ie, the R signal, is obtained from the other switch circuit (15). From the low pass filter (lO), 2G
+B and 2G+B+2R are smoothed to obtain a 2G+B+R signal, which is output from an output terminal (17) as a predetermined video signal by an encoder (IB).

Note that there is a color filter array shown in FIG. 8 that has the same performance as the color filter array shown in FIG. 3, but this is the same as the part surrounded by the broken line in FIG.
After all, the color filter array in FIG. 3 and the color filter array in FIG. 8 are the same. Such a color filter array is
In FIG. 2, there are two other ways if the way of division is changed, but if you consider the repetition, they are all the same as the color filter arrangement in FIG. 3.

FIG. 9 is a diagram showing another example of color filter arrangement.
Of the color filter array shown in FIG. 3, the ye filter and the Cy filter are interchanged. If this color filter array is represented as sampling for each color component as in FIG. 4, it will be as shown in FIG. 10. Figures 4 and 10
As is clear from comparing the figures, the sample positions of H and B have been swapped.

Therefore, when the mosaic filter having the color filter arrangement shown in FIG. 9 is applied to the system shown in FIG. Although the B signals are respectively output, the characteristics such as resolution and sensitivity are the same.

FIG. 11 shows a block of an imaging device using two solid-state imaging devices in which filters (1a) having the color filter arrangement shown in FIG. It is a circuit diagram.

In the figure, (lb) and (lc) are horizontal stripe color filters, (22) is a half mirror that divides the incident light from the optical system (18) into two, and (23) is a mirror.
, (2b) is a solid-state image sensor, which is a half mirror (
22), two solid-state image sensors (2
The same optical image is incident on a) and (2b). (20
(25) is a signal synthesis processing circuit that combines the outputs of the two solid-state image sensors (2a) and (2b) into a video signal in a predetermined format;
b) A drive signal generator that generates drive pulses.

In the solid-state imaging device configured as described above, when the positional relationship of the two solid-state imaging elements (2a) and (2b) is relatively shifted in the horizontal direction by a horizontal pixel pitch Pi ( (hereinafter referred to as "horizontal pixel shift")
, two solid-state image sensors (2a
The light receiving elements (pixels) of ) and (2b) are arranged in the horizontal direction, with different pixels of the solid-state image sensors (2a) and (2b) arranged for each pixel, as shown in Fig. 12. In the middle, the shaded pixels are pixels of the solid-state image sensor (2b), and the non-shaded pixels are the pixels of the solid-state image sensor (2b).
The pixel in a) is shown.

In this case, to apply the color filter array shown in FIG. 3, horizontal stripe color filters (lb) having the color filter arrays shown in 131f4 (A) and (B) are used.

(1c) are respectively solid-state image sensors (2a) and (2b
) horizontal stripe color filter (lb)
, (lc) are obtained by vertically dividing the color filter array shown in FIG. 3 into two and arranging them both horizontally and vertically.

And these horizontal stripe color filters (lb),
(lc) is only shifted by two lines in the vertical direction and has the same color filter arrangement, so it has the advantage that it can be manufactured by the same process. Also, the first
Using two solid-state image sensors with horizontal stripe color filters (1b) shown in Figure 3 (A), their positional relationship with each other is shifted horizontally by a horizontal pixel pitch Ph, and vertically by a vertical pixel pitch. As shown in FIG. 14, the color filter arrangement /'1 seen from the incident light image side becomes the same as the color filter arrangement shown in FIG. 3. In this case, either the drive timings of the two solid-state image sensors are shifted by the amount of the shift in the vertical direction, or the fourteenth
By delaying the output signals of the solid-state image sensor having the color filter array shown by the broken line in the figure by the amount of vertical shift, the signals corresponding to the color filters in the same row shown in FIG. 14 will be at the same timing. Because you can get
There is no need to manufacture two types of solid-state image sensing devices, which has the effect of making the device cheaper. This is exactly the same even when two solid-state image sensors having horizontal stripe color filters (Ic) shown in FIG. 13(B) are used.

In addition, when the positional relationship between the two solid-state image sensors (2a) and (2b) is relatively shifted in the vertical direction by the vertical pixel pitch PV, when viewed from the incident light image side, two solid-state image sensors (2a).

As shown in FIG. 15, the light-receiving pixels (2b) are pixels of different solid-state image sensors arranged in the vertical direction. In this case, to apply the filter with the color filter array shown in FIG. 3, the filter shown in FIG. 16(A),
Filter (ld) with the color filter arrangement shown in (B)
, (le) are arranged on each solid-state image sensor, and the color filter arrays shown in FIGS.
E, G, and W are arranged in a checkered pattern, which has the effect of providing a filter with less variation in spectral characteristics.

In the above, a case has been described in which filters using the color filter array shown in FIG. 3 are arranged in a staggered manner on a plurality of solid-state image sensors and applied to an image pickup apparatus.

It is clear that even when a filter using the color filter array shown in FIG. 9 is applied, the same structure can be achieved and the same effect can be obtained.

[Effects of the Invention] As described above, according to the present invention, the arrangement pattern of the color filters disposed in front of the solid-state image sensor has eight pixels (two pixels in the horizontal direction and four pixels in the vertical direction) as one unit, The position of each color filter constituting this one unit is C1J (f=1~2.j
= 1 to 4), a W filter that transmits all color light is used for Cl41C22, a second color filter is used for C12 and C24, and CII.

C23 and Cl3. Since filters of different complementary colors are disposed in C21, optical carriers of each color are generated at wide intervals except on the horizontal and vertical frequency axes, so moire fringes are less likely to occur and resolution is improved.

Furthermore, since the light utilization rate is increased, there is an effect that an imaging device with high sensitivity can be obtained. Furthermore, when the present invention is applied to a solid-state imaging device using two solid-state imaging devices with pixel shifting, when horizontal pixel shifting is performed, the color filters attached to the two solid-state imaging devices should be formed into horizontal stripe filters in the same arrangement. This makes it possible to manufacture filters in the same process, and in the case of vertical pixel shifting, the color filters attached to the two solid-state image sensors each have a checkerboard arrangement of two types of color filters. This has the effect of providing a filter that can be configured easily and has less variation in spectral characteristics.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of an embodiment of the present invention, FIG. 2 is a diagram showing a mosaic color filter which is the main part of this embodiment, and FIG. 3 is a diagram showing the color filter arrangement pattern of this mosaic color filter. Figure 4 is a diagram showing the array configuration of transmitted color light in this array unit, Figure 5 is a diagram showing the size and phase relationship of each color light carrier in this array unit on a two-dimensional frequency plane, and Figure 6 is a diagram showing one unit. 7 and 7 are diagrams showing the signals of each part of the embodiment shown in FIG. 1, FIG. 8 is a diagram showing another arrangement unit of color filters, and FIG. 9 is a diagram showing another arrangement example of the color filter arrangement unit. 10 is a diagram showing the arrangement configuration of transmitted color light in this arrangement example, FIG. 11 is a block circuit diagram of another embodiment of the present invention, and FIG. 12 is a diagram showing the arrangement of two solid-state image sensors in this embodiment. Figures 13(A) and 13(B) are diagrams showing the color filter arrangement pattern of two filters in this embodiment, and Figure 14 is a diagram showing the positional relationship of pixels that receive light when shifted in the direction. FIG. 15 is a diagram for explaining the scanning method of two solid-state image sensors in the embodiment shown in FIG.
A diagram showing the positional relationship of pixels that receive light when shifted by V/2, Figures 16 (A) and (B) are diagrams showing the color filter arrangement pattern of the two filters in this embodiment, and Figure 17 is a diagram showing the conventional color filter arrangement pattern. FIG. 18, a diagram showing an example of the arrangement of color filters in a color solid-state imaging device, is a diagram showing, on a two-dimensional frequency plane, the size and phase relationship of carriers of each color detected by this conventional solid-state imaging device. (la), (ld), (le)-"mosaic color filter, (lb), (lc)...horizontal stripe color filter, (2). (2a), (2b)...solid-state image sensor ,(3)
, (4), (5) ...IH delay element, (
8), (7), (8)...Arithmetic unit, (9)
, (10)...Bypass filter, (11)
...Low pass filter, (12), (13)...
・Modulator, (14), (15)...Switch circuit, (16)...Encoder, (20...Signal synthesis processing circuit, G...Green light transmission filter, Cy...Cyan color light Transmission filter, Ye...yellow light transmission filter,
W...Full color light transmission filter. In each figure, the same reference numerals indicate the same or corresponding parts.

Claims (3)

[Claims] (1) A solid-state image sensor in which a plurality of light-receiving elements each constituting one pixel are arranged in both horizontal and vertical directions, and a color filter disposed in front of the solid-state image sensor and transmitting different colored light as described above. A mosaic color filter arranged in a fixed pattern at a position facing each pixel, and a signal synthesis processing means that scans and extracts the optical image signal of the solid-state image sensor and synthesizes it into a video signal of a predetermined format. The arrangement pattern of the mosaic color filters is arranged in two horizontal directions.
When 8 color filters each having 4 pixels in the vertical direction are considered to be one unit, and the array position of this unit is expressed as C_i_j (i is the horizontal position, j is the vertical position), C_1_4 and C_2_2 are as follows. The first color filters that transmit all color light are C_1_2 and C_2_
4 is a second color filter that transmits only the color light in the selected spectral region, and C_1_1 and C_2_3 are respectively the color light that passes through the second color filter and a pair of complementary color lights that include mutually different color lights. A third color filter that transmits one complementary color light is provided to C_1_3 and C_2_1, and a fourth color filter that transmits the other complementary color light of the pair of complementary color lights is provided to C_1_3 and C_2_1.
A color solid-state imaging device characterized in that it has an array pattern in which color filters are arranged respectively. (2) the second color filter is a green light transmission filter;
2. The color solid-state imaging device according to claim 1, wherein the third color filter is a cyan light transmission filter, and the fourth color filter is a yellow light transmission filter. (3) the second color filter is a green light transmission filter;
2. The color solid-state imaging device according to claim 1, wherein the third color filter is a yellow light transmission filter, and the fourth color filter is a cyan color light transmission filter.