JP2008067058A - Solid-state imaging apparatus, signal processing method, and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid-state imaging apparatus having color filters for attaining high resolution, and also to provide a camera, and a signal processing method to be used for the solid-state imaging apparatus. <P>SOLUTION: The square array of the color filters for the portion of four pixels are two-dimensionally arrayed concerning the color filters provided in the solid-state imaging apparatus 102. One square array includes: G-filter two pixels for mainly transmitting the light of green; a GB filter one pixel for mainly transmitting light with green and blue; and an RG filter one pixel for mainly transmitting light with red and green. The G filters are arranged for alignment in a diagonal direction in the square array. The intensity IB of a blue component is acquired by subtracting the output of the pixel having the G filter from the output of the pixel having a GB filter. The intensity IR of a red component is acquired by subtracting the output of the pixel having the G filter from the output of the pixel having an RG filter. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a solid-state imaging device, a signal processing method, and a camera, and more particularly to a filter technique that realizes a high resolution.

In recent years, solid-state imaging devices widely applied in various fields such as digital cameras and mobile phones perform color imaging using a color filter.
(First prior art)
FIG. 13 is a diagram illustrating a configuration of a solid-state imaging device according to the first related art. As shown in FIG. 13, the solid-state imaging device 13 includes a plurality of pixels 1301, a vertical shift register 1302, a vertical signal line 1303, a row memory 1304, a horizontal shift register 1305, a horizontal signal line 1306, and an output amplifier 1307.

  When the pixel 1301 is selected by the vertical shift register 1302, it outputs a pixel signal to the vertical signal line 1303. The pixel signal is transferred to the row memory 1304 via the vertical signal line 1303. When the vertical shift register is selected, the row memory 1304 outputs a pixel signal to the horizontal signal line 1306. The pixel signal is output from the output amplifier 1307 via the horizontal signal line 1306.

Each of the plurality of pixels 1 includes a color filter that mainly transmits one of red (R), green (G), and blue (B) light. In this case, the color filters are arranged in a two-dimensional array of square arrays consisting of a total of four pixels, one pixel each for red and blue and two pixels for green.
(Second prior art)
FIG. 14 is a diagram illustrating a configuration of a solid-state imaging device according to the second conventional technique. The main difference from the solid-state imaging device 13 is the color filter color scheme. That is, as shown in FIG. 14, the color filter of the solid-state imaging device 14 is a two-dimensional square array composed of one pixel each of cyan (Cy), magenta (Mg), yellow (Ye), and green, for a total of four pixels. Colored as arranged.

(Third prior art)
FIG. 15 is a diagram illustrating a color filter of four pixels and a color arrangement of a solid-state imaging device according to the third prior art. The color filters of the solid-state imaging device 15 are arranged so that the square array shown in FIG. 15 is two-dimensionally arranged.
As shown in FIG. 15, the color filter included in the pixel 1501 among the four pixels constituting the square array is equally divided into four square regions, and mainly white (W), cyan, yellow, and green light respectively. Make it transparent. Among these, white is arranged diagonally outside the square array, and green is arranged inside. Further, cyan is arranged closer to the pixel 1502, and yellow is arranged closer to the pixel 1503.

Next, the color filter included in the pixel 1502 includes regions that mainly transmit cyan and green light, respectively. Green is a square region arranged diagonally inside the square array and occupies a quarter of the color filter of the pixel 1502.
The color filter included in the pixel 1503 includes regions that mainly transmit yellow and green light, respectively. Green is a square region arranged diagonally inside the square array and occupies a quarter of the color filter of the pixel 1503.

Now, white transmits any light of red, green and blue. Further, cyan mainly transmits green and blue, and yellow mainly transmits red and green.
Using this knowledge, the solid-state imaging device 15 calculates the intensity IR of the red component and the intensity IB of the blue component by the following equations.
IR = (3I1-2-2-I3) / 3 (Formula 1)
IB = (3I1-I2-2I3) / 3 (Formula 2)
Here, I1 to I3 are output values of the pixels 1501 to 1503, respectively (see Patent Document 1).

As described above, the solid-state imaging device performs color imaging using various color filters.
JP-A-2-266564

  However, if only light of a specific color is transmitted for each pixel as in the solid-state imaging devices 13 and 14 according to the prior art, the resolution (shading) for each color is lowered. In the solid-state imaging device 13, the number of pixels that receive red and blue is only one of the four pixels, so the resolution is reduced to a quarter. In addition, since the solid-state imaging device 14 receives only the red component of magenta and yellow, the red-related resolution is reduced to two-fourths.

In addition, in the solid-state imaging device 15 according to the related art, all pixels receive the green component, but in order to obtain the intensity IG of the green component, first, the red component IR and the blue color are obtained by (Expression 1) and (Expression 2) The strength with component IB must be determined. That is, in order to obtain the intensity of the green component IG, complicated signal processing must be performed, so that the color S / N deteriorates.
For this reason, when the pixels are miniaturized and the output value for each pixel becomes weak, deterioration in image quality is inevitable. In addition, it is difficult to miniaturize a pixel because it is necessary to arrange four color filters for each pixel. Therefore, there is a limit in improving the resolution in the solid-state imaging device 15 as well.

  The present invention has been made in view of the above-described problems, and is a solid-state imaging device and camera including a color filter that realizes high resolution, and a signal processing method used in such a solid-state imaging device. The purpose is to provide.

  In order to achieve the above object, a solid-state imaging device according to the present invention is a solid-state imaging device in which one group in which pixels including any of a plurality of types of filters are arranged is defined as one unit, and a plurality of the units are arranged. Each pixel of the unit includes only one type of filter, and all the filters transmit visible light in a common wavelength range.

In this way, since any color filter transmits light in the common wavelength range, high resolution can be achieved in the common wavelength range.
The solid-state imaging device according to the present invention subtracts the output of a pixel provided with a filter that transmits only light in the common wavelength range from the output of the pixel provided with a filter that transmits light in the visible wavelength range other than the common wavelength range. Thus, the intensity of light in the visible wavelength region other than the common wavelength region is obtained. In this way, the intensity for each primary color can be calculated by simple subtraction. Therefore, when calculating the intensity for each primary color, the signal processing circuit can be made simple and inexpensive because it does not have complicated signal processing as in the prior art.

The solid-state imaging device according to the present invention is characterized in that the common wavelength region is a green wavelength region. In this way, since the resolution is increased in the green wavelength range where the human visibility is the highest in the visible wavelength range, an image with a high resolution can be taken.
The filter may also transmit invisible light.
The solid-state imaging device according to the present invention is characterized in that the common wavelength range is either red or blue. In this way, since the red and blue wavelength regions are adjacent to the invisible wavelength region, the wavelength region extends to the boundary between the infrared wavelength region and the ultraviolet wavelength region without causing color mixing with the green wavelength region. Can be enlarged. Therefore, high resolution can be realized in a wider wavelength range.

The solid-state imaging device according to the present invention is characterized in that one unit pixel is arranged in a rectangle, and a filter that transmits light in a common wavelength region is arranged on a diagonal line of the rectangle. In this way, it is possible to pick up an image with a high resolution including the non-visible wavelength region.
A solid-state imaging device according to the present invention is a solid-state imaging device in which one group in which pixels each having a plurality of types of filters are two-dimensionally arranged is defined as one unit, and a plurality of the one unit is arranged, A non-visible light filter that mainly transmits invisible light is included, and filters other than the invisible light filter transmit visible light in a common wavelength range. In this way, since a filter that cuts invisible light such as an infrared cut filter is not required, the manufacturing cost can be reduced and the solid-state imaging device can be provided at low cost. Further, a primary color signal can be easily generated by a simple calculation mainly using a difference.

In addition, the common wavelength range may include any one of red, green, and blue wavelength ranges and a non-visible wavelength range.
The solid-state imaging device according to the present invention is characterized in that the filter is a multilayer interference filter. In this way, a high resolution can be realized by a finer color filter.

  The solid-state imaging device according to the present invention is characterized in that the filter that transmits only light in the red or blue wavelength region in the visible wavelength region is composed of a λ / 4 multilayer film. The filter that does not transmit light in the visible wavelength range may be formed by laminating two λ / 4 multilayer films having different center setting wavelengths. In this way, a high resolution can be realized with a color filter having a simpler structure. Also, the apparatus can be reduced in size and cost in the sense that it is not necessary to receive an ultraviolet filter or an infrared filter separately.

  In the signal processing method according to the present invention, one unit is arranged in a group in which pixels each having a plurality of types of filters are two-dimensionally arranged, and the one unit mainly transmits invisible light. A signal processing method executed by a solid-state imaging device that has a filter and filters other than the non-visible light filter are executed by a solid-state imaging device that transmits visible light in a common wavelength range, and a pixel signal output by a pixel including a filter other than the non-visible light filter From this, the intensity of visible light is obtained by subtracting a pixel signal output from a pixel having a non-visible light filter. In this way, high-resolution imaging can be realized with a simpler procedure.

  The camera according to the present invention is characterized by the solid-state imaging device according to the present invention. In this way, high resolution can be realized at low cost.

Hereinafter, embodiments of a solid-state imaging device and a signal processing method according to the present invention will be described with reference to the drawings, taking a digital still camera as an example.
[1] First Embodiment A digital still camera according to the present embodiment performs color imaging using a solid-state imaging device including a color filter. The solid-state imaging device according to the present embodiment has substantially the same configuration as the above-described conventional solid-state imaging device, but differs in the color arrangement of the color filters. Hereinafter, the description will be given focusing on the differences.

(1) Configuration of Digital Still Camera First, the configuration of the digital still camera according to the embodiment of the present invention will be described. FIG. 1 is a block diagram showing the main functional configuration of the digital still camera according to the present embodiment.
As shown in FIG. 1, the digital still camera 1 according to the present embodiment includes an optical system 101, a solid-state imaging device 102, and a video signal creation unit 103. The optical system 101 forms an image of light incident on the digital camera 1 on the imaging region of the solid-state imaging device 102.

The solid-state imaging device 102 photoelectrically converts incident light to generate and output a color signal. The video signal creation unit 103 processes the color signal output from the solid-state imaging device 102 to generate and output a color video signal.
(2) Color filter color scheme First, the color filter color scheme of the solid-state imaging device 102 will be described.

FIG. 2 is a schematic diagram illustrating a configuration of the solid-state imaging device 102. As shown in FIG. 2, the color filter included in the solid-state imaging device 102 is formed by two-dimensionally arranging a square array of color filters for four pixels.
In one square arrangement, a color filter that mainly transmits green light (hereinafter referred to as “G filter”) has two pixels, and a color filter that mainly transmits green and blue light (hereinafter referred to as “GB filter”). ”) And one pixel of a color filter (hereinafter referred to as“ RG filter ”) that mainly transmits red and green light. In this square array, the G filters are arranged in a diagonal direction.

The intensity IB of the blue component can be obtained by subtracting the output of the pixel (hereinafter referred to as “G pixel”) having the G filter from the output of the pixel including the GB filter (hereinafter referred to as “GB pixel”). Further, the intensity IR of the red component can be obtained by subtracting the output of the G pixel from the output of the pixel having the RG filter (hereinafter referred to as “RG pixel”).
Needless to say, the solid-state imaging device 102 includes a larger number of pixels than those shown in FIG. 2, and only a part of them is shown in FIG. The same applies to other embodiments and modifications. What is necessary is just to comprise a color filter, for example using materials, such as a pigment and dye.

(3) Summary According to the present embodiment, unlike the prior art, the GB pixel and the RG pixel also receive green light in addition to blue and red, so the brightness is clear and the resolution is improved. To do.
Further, since the human visibility is the highest in the green wavelength region of the visible wavelength region, the resolution can be further increased by detecting the intensity IG of the green component in all pixels.

Further, unlike the solid-state imaging device 15 according to the prior art, the intensity IR of the red component and the intensity IB of the blue component can be obtained by simple subtraction, thereby simplifying the signal processing circuit and reducing the cost. be able to.
It should be noted that the output of the G pixel is subtracted from the output of the GB pixel or the RG pixel when obtaining the intensity of the blue component or the red component, but in this case, the output of the G pixel may be the output of any G pixel. And it is good also as an average output of two G pixels.

[3] Second Embodiment Next, a second embodiment of the present invention will be described. The digital still camera according to the present embodiment has substantially the same configuration as the digital still camera according to the first embodiment, but is different in the color arrangement of the color filters. Hereinafter, the description will be given focusing on the differences.

(1) Color Filter Color Arrangement FIG. 3 is a diagram illustrating a configuration of a solid-state imaging device included in the digital still camera according to the present embodiment. As shown in FIG. 3, the color filter included in the solid-state imaging device 3 is formed by two-dimensionally arranging a square array of color filters for four pixels.
In one square arrangement, a color filter that mainly transmits light of green and blue (hereinafter referred to as “GB filter”) has two pixels, and a color filter that mainly transmits light of red and blue (hereinafter referred to as “GB filter”). "RB filter") includes one pixel, and a color filter that mainly transmits blue light (hereinafter referred to as "B filter") includes one pixel. In this square array, the GB filters are arranged in a diagonal direction.

The intensity IG of the green component can be obtained by subtracting the output of the pixel having the B filter (hereinafter referred to as “B pixel”) from the output of the GB pixel. Further, the intensity IR of the red component can be obtained by subtracting the output of the B pixel from the output of the pixel having the RB filter (hereinafter referred to as “RB pixel”).
The color filter may be configured using, for example, a material such as a pigment or a dye, or a configuration in which an infrared cut filter, an ultraviolet cut filter, or the like is formed on the color filter described in the third embodiment. You may take.

(3) Spectral Characteristics of Color Filter Next, spectral characteristics of the color filter according to the present embodiment will be described.
FIG. 4 is a graph showing the spectral characteristics of the color filter according to the present embodiment, where (a) shows the spectral characteristics of the B filter, (b) shows the spectral characteristics of the RB filter, and (c) shows the spectral characteristics. The spectral characteristics of the GB filter are shown respectively.

As shown in FIG. 4, each filter transmits light in a blue wavelength range that is a visible light wavelength range shorter than the reflection wavelength range.
In this way, the blue transmission band can be extended to the short wavelength side without causing color mixing between blue and green or color mixing between blue and red. Therefore, the sensitivity of blue can be improved and the resolution can be increased.

(4) Summary As described above, according to the present embodiment, the output of the GB pixel and the RB pixel receives blue light in addition to green and red, so that the resolution is improved.
Since any color filter transmits blue light, the intensity of red and green light can be obtained by simple subtraction. This eliminates the need for complicated filter arrangements and signal processing as in the prior art.

It should be noted that the output of the B pixel is subtracted from the output of the GB pixel and the RB pixel when obtaining the intensity of the green component and the red component, but in this case, the output of the B pixel may be an output of any B pixel. And it is good also as an average output of two B pixels.
[3] Third Embodiment Next, a third embodiment of the present invention will be described. The digital still camera according to the present embodiment has substantially the same configuration as the digital still camera according to the first embodiment, but is different in the color arrangement of the color filters. Hereinafter, the description will be given focusing on the differences.

(1) Color Filter Color Arrangement First, the color filter color arrangement of the solid-state imaging device included in the digital still camera according to the present embodiment will be described.
FIG. 5 is a diagram illustrating a configuration of the solid-state imaging device according to the present embodiment. As shown in FIG. 5, the color filter included in the solid-state imaging device 5 according to the present embodiment is also formed by two-dimensionally arranging a square array of color filters for four pixels.

  In one square arrangement, a color filter (hereinafter referred to as “GBI filter”) that mainly transmits light in green, blue, and invisible wavelength regions has two pixels, and light in red, blue, and invisible regions is mainly used. A color filter that transmits light (hereinafter referred to as “RBI filter”) includes one pixel, and a color filter that transmits light in blue and invisible wavelength regions (hereinafter referred to as “BI filter”) includes one pixel.

Since the solid-state imaging device 5 includes a non-visible light filter (not shown), that is, an infrared filter and an ultraviolet filter, only visible light is incident on the color filter. Therefore, the intensity IB of the blue component is obtained from the output of the BI pixel.
The intensity IG of the green component can be obtained by subtracting the output of a pixel (hereinafter referred to as “BI pixel”) including a BI filter from the output of a pixel including the GBI filter (hereinafter referred to as “GBI pixel”). Further, the intensity IR of the red component can be obtained by subtracting the output of the BI pixel from the output of the pixel having the RBI filter (hereinafter referred to as “RBI pixel”).

(2) Configuration of Color Filter Next, the configuration of the color filter according to the present embodiment will be described.
FIG. 6 is a cross-sectional view schematically showing the configuration of the color filter provided in the solid-state imaging device 102. As shown in FIG. 6, the color filter 6 according to the present embodiment is a multilayer interference filter in which a spacer layer 602 is sandwiched between λ / 4 multilayers 601 and 603. The λ / 4 multilayer film 601 is formed by alternately stacking dielectric layers 601s and 601t, and the λ / 4 multilayer film 603 is formed by stacking dielectric layers 603s and 603t alternately.

The dielectric layers 601s and 603s are both made of silicon dioxide (SiO ₂ ), and the dielectric layers 601t and 603t are both made of titanium dioxide (TiO ₂ ). The spacer layer 602 is made of silicon dioxide. The physical thicknesses of the dielectric layers 601s and 603s are both 103.4 nm, and the physical thicknesses of the dielectric layers 601t and 603t are both 60.0 nm.

The dielectric layers 601s, 601t, 603s, and 603t are all two layers, and the optical film thickness is 150 nm. Here, the optical film thickness means an index obtained by multiplying the physical film thickness by the refractive index.
More specifically, the refractive index 1.45 of silicon dioxide is multiplied by the physical thickness 103.4 nm of the dielectric layers 601s and 603s, and the physical film of the dielectric layers 601t and 603t is multiplied by the refractive index 2.51 of titanium dioxide. When the optical film thickness is obtained by multiplying the thickness of 60.0 nm, it becomes 150 nm.

The λ / 4 multilayer films 601 and 603 have a wavelength region (hereinafter referred to as “center setting wavelength”) corresponding to four times the optical film thickness 150 nm of the dielectric layers 601 s, 601 t, 603 s, and 603 t (hereinafter referred to as “center setting wavelength”). Hereinafter, the light of “reflection wavelength range” is reflected.
The color filter 6 transmits light having a wavelength corresponding to the thickness of the spacer layer 602 within the reflection wavelength range of the λ / 4 multilayer films 601 and 603.

In the present embodiment, the physical thickness of the spacer layer 602 is 5 nm by the BI filter, and has the same optical thickness as the silicon dioxide layer constituting the λ / 4 multilayer film. For this reason, the BI filter is a λ / 4 multilayer as a whole, and does not have a transmission wavelength region within the reflection wavelength region, but transmits blue light because it is outside the reflection wavelength region.
On the other hand, the film thicknesses of the GBI filter and the RBI filter are 30 nm and 130 nm, respectively, and the optical film thickness is different from that of the silicon dioxide layer.

As can be seen from the above, since the physical film thickness and the number of layers of the dielectric layers 601s and 601t are common among the three filters G, GB, and RG, the three filters are formed simultaneously in one semiconductor process. Can do.
(3) Spectral Characteristics of Color Filter Next, spectral characteristics of the color filter according to the present embodiment will be described.

FIG. 7 is a graph showing the spectral characteristics of the color filter according to the present embodiment, where (a) shows the spectral characteristics of the BI filter, (b) shows the spectral characteristics of the RBI filter, and (c) shows the spectral characteristics. The spectral characteristics of the GBI filter are shown respectively.
As shown in FIG. 7, in any of the filters BI, RBI, and GBI, the wavelength range centering on the wavelength of 600 nm is the reflection wavelength range of the λ / 4 multilayer film. Further, both transmit light in a blue wavelength range that is a visible wavelength range shorter than the reflection wavelength range.

In this way, it is possible to extend the blue transmission band without generating a color mixture between blue and green or a color mixture between blue and red. Therefore, the sensitivity of blue can be improved and the resolution can be increased. If the infrared filter or the ultraviolet filter is removed, even the invisible light can be detected and the resolution can be improved.
Also, the resolution is improved in the sense that the GBI pixel and the RBI pixel receive blue and invisible light in addition to green and red.

[4] Fourth Embodiment Next, a digital still camera according to a fourth embodiment of the present invention will be described. The digital still camera according to the present embodiment has substantially the same configuration as the digital still camera according to the first embodiment, but is different in the color arrangement of the color filters. Hereinafter, the description will be given focusing on the differences.

(1) Color Filter Color Arrangement FIG. 8 is a diagram illustrating a main configuration of a solid-state imaging device included in the digital still camera according to the present embodiment. As shown in FIG. 8, the color filter included in the solid-state imaging device 8 according to the present embodiment is also formed by two-dimensionally arranging a square array of color filters for four pixels.
One square array includes one pixel each of a color filter (hereinafter referred to as “I filter”) that mainly transmits light in a non-visible wavelength region, a BI filter, a GBI filter, and an RBI filter.

The intensity IB of the blue component can be obtained by subtracting the output of a pixel having an I filter (hereinafter referred to as “I pixel”) from the output of the BI pixel. The red component intensity IR and the green component intensity IG can be obtained by subtracting the output of the BI pixel from the output of the RBI pixel and the output of the GBI pixel, respectively.
(2) Configuration of Color Filter Since the BI, GBI, and RBI filters are the same as those in the third embodiment, description thereof is omitted. The I filter is formed by laminating a λ / 4 multilayer film having a center setting wavelength of 520 nm on a λ / 4 multilayer film having a center setting wavelength of 600 nm.

(3) Spectral Characteristics of Color Filter Next, spectral characteristics of the color filter according to the present embodiment will be described. FIG. 9 is a graph showing the spectral characteristics of the color filter according to the present embodiment, where (a) shows the spectral characteristics of the RBI filter, (b) shows the spectral characteristics of the GBI filter, and (c) shows the BI filter. (D) shows the spectral characteristics of the I filter.

As shown in FIG. 9, all of the RBI, GBI, and BI filters have a wavelength of 600 nm as a center setting wavelength, the RBI filter transmits red light, and the GBI filter transmits green light. The I filter reflects light in a reflection wavelength region having a center setting wavelength of 520 nm and a center setting wavelength of 600 nm, and transmits only invisible light.
(4) Summary As described above, in this embodiment, an I pixel is provided for each square array of four pixels, so that an ultraviolet filter and an infrared filter are not required as in the third embodiment. The intensity of visible light can be obtained by removing the invisible component by simple subtraction. Therefore, since the number of parts of the digital still camera can be reduced, the parts cost and the manufacturing cost can be reduced, and the digital still camera can be provided at low cost.

Further, since the BI pixel receives invisible light and the GBI pixel and RBI pixel receive blue and invisible light, the resolution is improved.
[5] Modifications Although the present invention has been described based on the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments, and the following modifications can be implemented. .

(1) In the second embodiment, the case where all the four pixels constituting the square array transmit blue light has been described, but it goes without saying that the present invention is not limited to this. It may be as follows.
That is, all four pixels constituting the square array may transmit red light instead of blue. FIG. 10 is a diagram illustrating the color arrangement of the color filters provided in the solid-state imaging device according to this modification.

  As shown in FIG. 10, in the color filter included in the solid-state imaging device 10 according to the present modification, one square array is a color filter that mainly transmits red light (hereinafter referred to as “R filter”). ) Is 2 pixels, the RB filter is 1 pixel, and the RG filter is 1 pixel. In this square array, the R filters are arranged in a diagonal direction.

In this way, the transmission wavelength range of red light can be extended to the long wavelength side until it contacts the infrared wavelength range without causing color mixing with green or blue light. Therefore, high resolution can be realized in a wide wavelength region on the red side.
(2) In the third embodiment, the case where all the four pixels constituting the square array transmit green light has been described, but it goes without saying that the present invention is not limited to this. It may be as follows.

That is, all four pixels constituting the square array may transmit red light instead of blue. FIG. 11 is a diagram illustrating the color arrangement of the color filters provided in the solid-state imaging device according to this modification.
As shown in FIG. 11, in the color filter included in the solid-state imaging device 11 according to the present modification, a color filter (hereinafter referred to as “hereinafter referred to as“ color filter ”) that mainly transmits red, green, and invisible light is included in one square array. RGI filter ”) includes two pixels, one color filter (hereinafter referred to as“ RI filter ”) that mainly transmits red and invisible light, and one RBI filter pixel. In this square array, the RGI filters are arranged in a diagonal direction.

In this way, the transmission wavelength range of red light can be extended to the long wavelength side until it contacts the infrared wavelength range without causing color mixing with green or blue light. Therefore, high resolution can be realized in a wide wavelength region on the red side.
If a non-visible light filter is used, the intensity IR of the red component can be obtained from a pixel having an RI filter (hereinafter referred to as “RI pixel”).

Furthermore, the intensity IG of the green component can be obtained by subtracting the output of the RI pixel from the output of the pixel having the RGI filter (hereinafter referred to as “RGI pixel”), and the output of the RI pixel is subtracted from the output of the RBI pixel. By pulling, the strength IB of the blue component can be obtained.
The color filter according to the present modification is a multilayer interference filter similar to the color filter according to the third embodiment. The λ / 4 multilayer film constituting the color filter according to this modification is composed of a silicon dioxide layer and a titanium dioxide layer, each having four layers.

The dielectric layers constituting the λ / 4 multilayer film all have an optical film thickness of 125 nm, and the λ / 4 multilayer film reflects light in the reflection wavelength region having a center setting wavelength of 500 nm. The silicon dioxide layer has a refractive index of 1.45 and a physical film thickness of 86.2 nm, and the titanium dioxide layer has a refractive index of 2.51 and a physical film thickness of 49.8 nm.
The spacer layers are all made of silicon dioxide, and in the RI filter, the optical thickness of the spacer layer is 125 nm. For this reason, the RI filter is a λ / 4 multilayer as a whole, and reflects light in the reflection wavelength region having a center setting wavelength of 500 nm. Further, the spacer layer of the RGI filter has an optical film thickness of 5 nm, and the RBI filter has a thickness of 130 nm, both of which have a structure different from the silicon dioxide layer forming the λ / 4 multilayer film.

FIG. 12 is a graph showing the spectral characteristics of the color filter according to this modification, where (a) shows the spectral characteristics of the RI filter, (b) shows the spectral characteristics of the RBI filter, and (c) shows the RGI. Each represents the spectral characteristics of the filter.
As shown in FIG. 12, in this modification, since any filter transmits red light, the resolution in the red wavelength region is high. Further, if the invisible light filter is removed, light in the invisible wavelength region can also be imaged.

(3) In the above embodiment, the case where silicon dioxide and titanium dioxide are used as the material of the dielectric layer constituting the multilayer interference filter has been described, but it goes without saying that the present invention is not limited to this. Instead of tantalum oxide (Ta ₂ O ₅ ), zirconium oxide (ZrO ₂ ), silicon nitride (SiN), silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ ), magnesium fluoride (MgF ₂ ) Hafnium oxide (HfO ₃ ) or magnesium oxide (MgO ₂ ) may be used. The effect of the present invention is the same regardless of which material is used.

  (4) In the above embodiment, the case where one of the dielectric layers constituting the λ / 4 multilayer film constituting the multilayer interference filter and the spacer layer are made of the same material has been described, but the present invention is not limited to this. Needless to say, instead of this, the dielectric layer and the spacer layer may be made of different materials. In this case, regardless of the material of the spacer layer, if the optical film thickness is as described above, the spectral characteristics of the multilayer interference filter are the same.

  The solid-state imaging device, the camera, and the signal processing method according to the present invention are useful as a technique for color imaging with high resolution.

It is a block diagram which shows the main function structures of the digital still camera which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the solid-state imaging device 102 which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the structure of the solid-state imaging device which concerns on the 2nd Embodiment of this invention. It is a graph which shows the spectral characteristic of the color filter which concerns on the 2nd Embodiment of this invention, Comprising: (a) is the spectral characteristic of B filter, (b) is the spectral characteristic of RB filter, (c) Indicates the spectral characteristics of the GB filter. It is a schematic diagram which shows the structure of the solid-state imaging device which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows typically the structure of the color filter with which the solid-state imaging device 5 which concerns on the 3rd Embodiment of this invention is provided. 10 is a graph showing spectral characteristics of a color filter according to a third embodiment of the present invention, where (a) shows the spectral characteristics of the BI filter, (b) shows the spectral characteristics of the RBI filter, and (c). Indicates the spectral characteristics of the GBI filter. It is a schematic diagram which shows the structure of the solid-state imaging device which concerns on the 4th Embodiment of this invention. It is a graph which shows the spectral characteristic of the color filter which concerns on the 4th Embodiment of this invention, Comprising: (a) is the spectral characteristic of an RBI filter, (b) is the spectral characteristic of a GBI filter, (c) is BI The spectral characteristics of the filter are shown, and (d) shows the spectral characteristics of the I filter. It is a figure which shows the color scheme of the color filter which concerns on the modification (1) of this invention. It is a figure which shows the color scheme of the color filter which concerns on the modification (2) of this invention. It is a graph which shows the spectral characteristic of the color filter which concerns on the modification (2) of this invention, Comprising: (a) is the spectral characteristic of RI filter, (b) is the spectral characteristic of RBI filter, (c) is Respective spectral characteristics of the RGI filter are represented. It is a figure which shows the structure of the solid-state imaging device which concerns on a 1st prior art. It is a figure which shows the structure of the solid-state imaging device concerning 2nd prior art. It is a figure which shows the structure of the solid-state imaging device which concerns on a 3rd prior art.

Explanation of symbols

1 ………………………………………………… Digital still camera 3 ………………………………………………… Color filters 3, 5, 8 10, 11, 13, 14 ............ Solid-state imaging device 15, 102 …………………………………… Solid-state imaging device 101 ………………………………………… …… Optical system 103 ……………………………………………… Video signal generators 601 and 603... ..Λ / 4 multilayer film 602. ………………………………………… Spacer layers 601 s, 601 t, 603 s, 603 t ... Dielectric layers 1301, 1501, 1502, 1503 ... Pixel 1302 ……………………………… ………… Vertical shift register 1303 …………………………………… Vertical signal line 1304 ………………………………………… Line Memo 1305 ............ ……………………………… Horizontal shift register 1306 ………………………………………… Horizontal signal line 1307 ……………………… ………………… Output Amplifier

Claims (13)

A solid-state imaging device in which one group in which pixels including any of a plurality of types of filters are arranged is defined as one unit, and a plurality of the one unit is arranged,
Each pixel of the unit includes only one type of filter,
A solid-state imaging device characterized in that any filter transmits visible light in a common wavelength region. By subtracting the output of a pixel with a filter that transmits only light in the common wavelength range from the output of the pixel with a filter that transmits light in the visible wavelength range other than the common wavelength range, the visible wavelength outside the common wavelength range The solid-state imaging device according to claim 1, wherein the intensity of light in the region is obtained. The solid-state imaging device according to claim 1, wherein the common wavelength region is a green wavelength region. The solid-state imaging device according to claim 1, wherein the filter also transmits invisible light. The solid-state imaging device according to claim 1, wherein the common wavelength range is either a red wavelength range or a blue wavelength range. One unit pixel is arranged in a rectangle,
The solid-state imaging device according to claim 1, wherein a filter that transmits light in a common wavelength region is arranged on the diagonal of the rectangle. A solid-state imaging device in which one group in which pixels each having a plurality of types of filters are two-dimensionally arranged is defined as one unit, and a plurality of the one unit is arranged,
The unit has a non-visible light filter that mainly transmits invisible light,
A solid-state imaging device, wherein a filter other than the non-visible light filter transmits visible light in a common wavelength range. The solid-state imaging device according to claim 1, wherein the common wavelength range includes any one of red, green, and blue wavelength ranges and a non-visible wavelength range. The solid-state imaging device according to claim 1, wherein the filter is a multilayer interference filter. The solid-state imaging device according to claim 1, wherein the filter that transmits only light in the red or blue wavelength region in the visible wavelength region is formed of a λ / 4 multilayer film. 2. The solid-state imaging device according to claim 1, wherein the filter that does not transmit light in the visible wavelength range is formed by laminating two λ / 4 multilayer films having different center setting wavelengths. A group of one-dimensionally arranged pixels each having a plurality of types of filters is arranged in a plurality of units, and each unit has a non-visible light filter that mainly transmits invisible light. The filter other than is a signal processing method executed by a solid-state imaging device that transmits visible light in a common wavelength range,
A signal processing method characterized in that the intensity of visible light is obtained by subtracting a pixel signal output from a pixel including a non-visible light filter from a pixel signal output from a pixel including a filter other than the non-visible light filter. A camera comprising the solid-state imaging device according to claim 1.

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