JPH0983726A - Color image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain color correction without using a color signal correction processing circuit nor giving any change to the color material of the colored film of a color filter and an image sensor. SOLUTION: A colored film 5 is formed on a color filter substrate 9 for dispersion of three colors and then placed on an image sensor substrate 1 against three photodetectors provided on the substrate 1. At the same time, an adhesive 6 is applied between the film 5 of the substrate 9 and the substrate 1. The adhesive 6 contains the pigment grains for color correction. The color balance can be corrected just with adjustment of the color and amount of pigment grains that are mixed into the adhesive 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image sensor used in a reading device applied to a copying machine, an image scanner, a facsimile or the like.

[0002]

2. Description of the Related Art Conventionally, in an image sensor having a color filter attached thereto, is color correction of each color of blue (B), green (G) and red (R) performed by a color signal correction processing circuit of the color image sensor? In many cases, a method such as changing the pigment or dye of the material of the colored film formed on the color filter to be bonded or adjusting the film thickness of the colored film is used.

When performing color correction of a color image sensor by a color signal correction processing circuit, for example, Japanese Patent Laid-Open No. 62-2
As described in the color original image reading apparatus of Japanese Patent No. 93877, color unevenness of the read original is eliminated by providing a color signal correction circuit for each signal output of the color linear image sensor. As a result, it is possible to correct to the desired color correction value. However, the color signal correction circuit is generally provided separately from the color image sensor, and accordingly, the configuration of the color original reading device becomes large.

Further, a method of changing the components or concentrations of pigments or dyes which are materials of the colored film of the color filter, or a method of changing the spectral sensitivity of the color filter by changing the film thickness, the color correction is performed. It is performed by many color filter manufacturers and is already known. However, each time the material composition of the color material used for the color filter or the film thickness of the color material is changed, the production line must be stopped, the color material must be changed, and the manufacturing conditions such as the film thickness must be changed to correct the color. The complication was occurring.

Therefore, for example, Japanese Patent Laid-Open No. 63-42271.
As disclosed in the publication, a method has been used in which the photosensitive pixel is changed in area ratio according to the transmittance of the color filters of blue, green, and red light of the color filter. On the other hand, the same thing can be achieved by changing the color filter area of each color light of blue, green, and red to be attached to the image sensor instead of the pixel area according to the transmittance. Conceivable.

However, a large amount of cost and design time are required for designing the colored film of the color filter and the pixel area of the image sensor, and for making the photomask, and therefore it cannot be easily changed after the designing and making of the photomask. Also, changing the material and film thickness of the colored film of the color filter involves changes in the manufacturing conditions in many manufacturing processes related to film formation of three colors of blue, green, and red, and pattern production. It is necessary to stop the production and prepare for manufacturing, which leads to an increase in cost.

As described above, in the conventional method, the color correction depends on the color signal correction processing circuit, or the spectral transmittance characteristic of the color material of the color filter is changed, the thickness of the color filter is changed, or the color filter is changed. Change of photosensitive film area,
I had to deal with it by changing the pixel area of the image sensor. Therefore, it took a lot of time and a large amount of cost, which was a hindrance.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and in a color image sensor having a color filter provided on a solid-state image sensor, a color signal correction processing circuit is not required, An object of the present invention is to provide a color image sensor capable of color correction without changing the color material of the colored film of the color filter or the image sensor.

[0009]

According to the present invention, in a color image sensor having a color filter provided on a solid-state image sensor, a colored layer different from the colored film of the color filter is provided on the solid-state image sensor. The color balance of each color is adjusted by the colored layer. The colored layer may be an adhesive used when the color filters are attached to each other, as in the invention described in claim 2, and the adhesive may be used in the invention described in claim 3. Those containing pigment particles or dyes for color adjustment can be used. Alternatively, as in the invention according to claim 4, the colored layer can be an overcoat of the color filter, and the overcoat as in the invention according to claim 5 is a pigment for color adjustment. Particles or dyes can be included.

[0010]

1 is a cross-sectional view showing a first embodiment of a color image sensor of the present invention. In the figure,
1 is an image sensor substrate, 2 is an electrode, 3 is an amorphous Si layer, 4 is an ITO layer, 5 is a colored film, 6 is an adhesive, 7 is an Au wire, 8 is a Si resin, 9 is a color filter substrate, and 10 is an IC. Is.

An electrode 2, an amorphous Si layer 3, and an ITO layer 4 are laminated on the image sensor substrate 1 to form individual light receiving elements. In FIG. 1, three light-receiving elements are shown so as to read images of different colors, and the light-receiving elements are arranged in a direction penetrating the figure to form a one-dimensional color image sensor. .

Further, the image sensor board 1 has an IC 1
0 is mounted, and is electrically connected to the wiring by bonding with an Au wire 7. This portion is fixed by Si resin 8 or the like.

The color filter substrate 9 is a substrate made of glass, and the colored film 5 is used as a light receiving element so that the colored film 5 for splitting into three colors faces the three light receiving elements of the image sensor substrate 1. It is arranged on the image sensor substrate 1. The color filter substrate 9 and the image sensor substrate 1 are attached to each other with an adhesive 6. Adhesive 6
Is an epoxy adhesive and is applied so as to fill the space between the colored film 5 and the image sensor substrate 1.

As the adhesive 6 to which the color filters are attached, a high transmittance is generally required in the entire visible light region. Epoxy resin is generally used as an adhesive for bonding color filters, but on the other hand, the adhesiveness for fixing chip parts (epoxy thermosetting type) "JU series" sold by Hiroki Co., Ltd. For this reason, an epoxy adhesive containing pigment particles is sold. Thus, it is possible to mix pigment particles into the epoxy component adhesive.

The method for producing a pigment dispersion type color filter is to disperse a colorant such as an organic pigment in a resin such as polyimide,
It is relatively easy to disperse the pigment particles in the epoxy adhesive, as in the case of applying this on a glass substrate.

The three-color spectral characteristics of the color image sensor are
Multiply the spectral sensitivity characteristics of the image sensor substrate, the spectral transmittance of the color filter, and the spectral distribution of the light source at each wavelength, and if there is something that transmits light between the original and the image sensor, then the spectral transmittance. Need to multiply. Further, in the case of a color image sensor of a type in which a color filter is attached to the image sensor as shown in FIG. 1, it is necessary to multiply the spectral transmittance of the adhesive 6 to which the color filter is attached. That is, the adhesive 6 is also related to the three-color spectral characteristic, and normally, the adhesive having a high transmittance in the entire visible light region was used. However, the first aspect of the present invention
In the embodiment, conversely, pigment particles or dyes are mixed with the adhesive agent 6 to adjust the three-color spectral characteristic to a desired value.

FIG. 2 is a graph showing an example of the spectral transmittance curve of the color filter, FIG. 3 is a graph showing an example of the spectral sensitivity characteristic of the light receiving element, and FIG. 4 is a case where an adhesive having a high transmittance is used. 4 is a graph showing an example of light receiving sensitivity in the image sensor of FIG. Now, assume that a color filter having a transmittance curve as shown in FIG. 2 is used. This color filter as a single unit has good transmittance characteristics as shown in FIG. However, when considering the three-color spectral characteristic of the color image sensor, it depends on the spectral sensitivity characteristic of the image sensor and the transmittance of each of the other layers as described above.
Here, each light receiving element is assumed to have a spectral sensitivity characteristic as shown in FIG. Furthermore, the spectral distribution characteristics of the light source that illuminates the original document also have an effect. In FIG. 4, the graph indicated by the alternate long and short dash line is the spectral distribution characteristic of the daylight fluorescent lamp used as the light source. Using such a light source, a color filter having a transmittance characteristic as shown in FIG. 2 is used, and light is received by a light receiving element having a spectral sensitivity characteristic as shown in FIG. 3 through each color filter.

When an adhesive having a high transmittance in the visible light region is used without mixing a pigment or a dye in the adhesive, the light receiving sensitivity when received by each light receiving element and converted into an electric signal is
As shown in FIG. In FIG. 4, the spectral sensitivity of the monochrome sensor when receiving light is shown by a chain double-dashed line. Also,
In color reading, the light receiving sensitivity of each color is shown by the solid line for the light receiving element corresponding to the blue filter.
The case of the light receiving element corresponding to the green filter is indicated by a broken line, and the case of the light receiving element corresponding to the red filter is indicated by a dotted line. At this time, the sensitivity ratio of blue, green, and red is B: G: R =
It is 0.70: 1.00: 0.59, which shows that the color balance is lost. Compared to reading with a monochrome sensor at this time, the ratio is B: G: R = 0.249:
It becomes 0.355: 0.210. When the color balance is broken like this, the conventional design is to remake the color filter or change the pixel area of the image sensor so that the sensitivity ratio of each color of blue, green, and red becomes similar. There was a need for change.

FIG. 5 is a graph showing an example of a spectral curve of a cyan color pigment, and FIG. 6 is a graph showing an example of a spectral transmittance curve when a colored layer mixed with a cyan color pigment is provided. As described above, when the sensitivity of green is strong, it can be corrected by the cyan pigment having the spectral characteristic as shown in FIG. Such a pigment was mixed in the adhesive 6 to bond the color filter having the spectral transmittance characteristic as shown in FIG. When the color filter is bonded by using the adhesive mixed with the cyan pigment in this manner, the spectral transmittance by the adhesive layer and the color filter has a distribution as shown by a thick line in FIG.

FIG. 7 is a graph showing an example of light receiving sensitivity in an image sensor when an adhesive having high transmittance is used. Similar to the above-mentioned case, a fluorescent lamp having a spectral distribution characteristic shown by a chain line in FIG. 7 is used, a color filter having a transmittance characteristic as shown in FIG. 2 and a pigment having a spectral characteristic as shown in FIG. Is used to cause the light receiving element having the spectral sensitivity characteristic as shown in FIG. 3 to receive light through the filter of each color and the adhesive in which the pigment is mixed. In this case, the light receiving sensitivity when the light is received by each light receiving element and converted into an electric signal is as shown in FIG. In FIG. 7, similarly to FIG. 4, the light receiving sensitivity of the light receiving element corresponding to the blue filter is indicated by a solid line, the light receiving sensitivity of the light receiving element corresponding to the green filter is indicated by a broken line, and the light receiving sensitivity of the light receiving element corresponding to the red filter is received. The sensitivity is shown by the dotted line. Furthermore, the spectral sensitivity when receiving a monochrome image is shown by a chain double-dashed line.

When the cyan pigment is mixed in the adhesive as described above, the sensitivity of the color image sensor is lower than that of green, and the sensitivity ratio of blue, green and red is B:
G: R = 0.97: 1.00: 0.92, which is blue,
The sensitivity ratios of green and red are close to each other. in this way,
The color balance of the color image sensor can be adjusted by including pigment particles in the adhesive agent for bonding the color filters. Therefore, there is no need for an output correction processing circuit in the color image sensor unlike the conventional case,
Further, there is no need to remake the color filter or change the design of the image sensor, so that cost reduction and process reduction can be achieved at the same time.

Although the cyan pigment is mixed in the adhesive in the above-mentioned example, the pigment may be mixed in the adhesive in a color and in an amount corresponding to the color balance. Further, a method of dyeing with a dye instead of the pigment particles can be considered. As for the method of dyeing the epoxy adhesive, the adhesive may be dyed with a dye in the same manner as the method of producing the dyed color filter.

Next, a second embodiment of the color image sensor of the present invention will be described. In the above-described first embodiment, the example in which the pigment or dye is contained in the adhesive used for adhering the color filter has been shown. The present invention is not limited to this. The second embodiment shows an example in which a pigment or a dye is contained in the overcoat of the color filter. The configuration of the color image sensor in the second embodiment is the same as that in the first embodiment shown in FIG. 1, and therefore its explanation is omitted here.

FIG. 8 is a sectional view of an example of a color filter. In the figure, 5 is a colored film, 9 is a color filter substrate, and 1 is a color filter substrate.
1 is an overcoat. The color filter overcoat 11 is provided for the purpose of improving moisture resistance and smoothness. Also, this overcoat 1
Since the material of No. 1 is used for color filters,
Generally, high transmittance is required in the entire visible light region.
Generally, an epoxy resin, an acrylic resin, a polyimide resin or the like having the above characteristics is used as an overcoat material for a color filter. It is relatively easy to color these resins by adding pigment particles or dyes to the resin component. Similar to the method for manufacturing a pigment dispersion type color filter, a coloring material such as an organic pigment may be dispersed in these resins. In the second embodiment, the overcoat 11 contains a pigment or a dye to adjust the color balance.

FIG. 9 is a flow chart showing an example of a process for producing a color filter. First, in S21, the color filter substrate 9 made of glass is prepared, and in S22,
A black matrix is formed on the color filter substrate 9 by using the photolithography technique, and then S23 to S4.
In 9, the blue, green, and red colored films 5 are formed. Since the process of forming the colored film 5 of each color is the same, the blue colored film will be described. A blue resist is applied in S23 and dried in S24. Further, an oxygen barrier film is applied in S25, dried in S26, exposed in S27 using a blue mask, developed in S28, washed in S29, and washed in S29.
It is dried at 30 and baked at S31 to form a blue filter portion. Similarly, a green filter portion is formed in steps S32 to S40, and a red filter portion is formed in steps S41 to S49.

After each of the blue, green and red colored films 5 is formed in this way, an overcoat is applied in S50 and baked in S51. Then, in S52, it is cut into a shape to be mounted on the image sensor, and inspected in S53, and a color filter for the image sensor as shown in FIG. 8 is completed. Then, the manufactured color filter is attached to the image sensor with an adhesive to manufacture a color image sensor as shown in FIG.

In the second embodiment, as the overcoat material applied in S50, acrylic, polyimide or epoxy resin mixed with pigment particles or dyes is used to adjust the sensitivity ratio of the color image sensor to a desired value. Are used. As described above, by coloring the overcoat 11 of the color filter, a color image sensor having an adjusted sensitivity ratio can be manufactured.

In the method of changing the design of the pixel area, which is one of the conventional color balance adjusting methods, S22, S
27, S36, S45, and other changes in the mask used, and the amorphous Si layer 3 and ITO 4 in the light receiving element.
Need to be changed, which requires a large amount of creation cost and time. Further, in the method of adjusting the color balance by changing the coloring material and the film thickness of the colored film 5, S23, S24, S27 to S27.
29, S31 to S33, S36 to S38, S40 to S4
2, it is necessary to change the conditions of each step of S45 to S47. Since adjustment of each of these processes must be performed individually, it is costly and time consuming. But,
In the method in which the pigment or dye is contained in the overcoat as in the second embodiment, it is only necessary to change the manufacturing conditions in S50 and S51, and it is possible to minimize the change in the manufacturing process of the color filter. .

As described above, the spectral characteristics of the color image sensor are the spectral sensitivity characteristics of the respective light receiving elements, the spectral transmittance of the color filter, the spectral distribution of the light source, and further between the original and the image sensor. If there is something that transmits light, it is determined by its spectral transmittance. In the second embodiment, since the overcoat 11 contains a pigment or the like, the spectral transmittance of the overcoat 11 also contributes. In addition, it is generally necessary to consider the spectral transmittance of the adhesive to which the color filter is attached, and in particular, when the adhesive contains a pigment or the like as in the above-described first embodiment, the spectral transmittance thereof is increased. Will need to be multiplied.

Similar to the above-described first embodiment, a color filter having a transmittance characteristic as shown in FIG. 2 is produced, and a cyan pigment having a spectral characteristic as shown in FIG. Mixed in. In such a configuration, the colored films 5 of the color filter and the overcoat 11 containing the cyan pigment have a spectral transmittance as shown by a thick line in FIG. Thus, even when the cyan pigment is contained in the overcoat 11, the same spectral transmittance as that in the case where the cyan pigment is contained in the adhesive 6 in the first embodiment described above is obtained. You can

In the second embodiment, the adhesive 6 has a high transmittance in the entire visible light region. For example,
Shin-Etsu Chemical Co., Ltd. Si-based adhesive KJR-9022 is 99% or more of the total visible light region, and Hysole's epoxy adhesive H.
L-8800-33 has a transmittance of 95% or more of the entire visible light region. Here, as an example, the Si-based adhesive KJR- manufactured by Shin-Etsu Chemical Co., Ltd., which has a light transmittance of 99% or more in the visible light region.
Using 9022, a color filter was adhered to manufacture an image sensor.

Similar to the first embodiment, a daylight color fluorescent lamp having the spectral distribution characteristic shown by the alternate long and short dash line in FIGS. 4 and 7 is used, and a light receiving element having the spectral sensitivity characteristic as shown in FIG. 3 is used. Receive light. When no pigment is mixed into the overcoat 11, the photosensitivity is as shown in FIG. 4, and the sensitivity ratio of blue, green and red in this case is B: G: R = 0.
It was 70: 1.00: 0.59. Overcoat 1
By including cyan pigment in No. 1, an image sensor having a light receiving sensitivity as shown in FIG. 7 could be manufactured. As a result, the sensitivity ratio of blue, green, and red is B:
G: R = 0.97: 1.00: 0.92, which is blue,
The sensitivity ratio of green and red has been improved to a value that is approximately similar. In this way, by including pigment particles in the overcoat 11, the color balance of the color image sensor can be adjusted. Therefore, there is no need for an output correction processing circuit in the color image sensor as in the past, and in the color filter, the design of the filter section for each color, the color material, the film thickness, the manufacturing conditions, and the like, and the design of the light receiving element are designed. There is no need to change, and the cost and time required for adjusting the sensitivity ratio can be achieved at the same time.

In the above-mentioned example, the cyan pigment is mixed in the overcoat material 11. However, a pigment having a color and an amount corresponding to the color balance adjustment amount may be mixed in the overcoat material. Further, a method of dyeing with a dye instead of the pigment particles can be considered.

In each of the above-described embodiments, an example in which the adhesive 6 or the overcoat 11 contains a pigment or a dye is shown. However, in the present invention, except for the colored film of the color filter which passes through before reaching the light receiving element. The color balance can be adjusted by incorporating pigments or dyes into various layers of the above. Further, not only one layer but also a plurality of layers may contain pigments or dyes to adjust the color balance. For example, the above-mentioned adhesive 6 and overcoat 11
Pigments or dyes can be contained in the two layers. At this time, the colors of the pigments or dyes contained in the respective layers may be different colors, and may be the same color. Further, another layer may be provided for adjusting the color balance.

In each of the above embodiments, blue, green,
An example in which a color image is obtained with three colors of red has been shown, but the present invention is not limited to this, and the same configuration can be made when other input colors are used.

[0036]

As is apparent from the above description, according to the present invention, a layer different from the colored film of the color filter is used as a colored layer on the solid-state image sensor, and the color balance is adjusted by the colored layer. Therefore, the color correction processing circuit is not required and the color balance can be easily adjusted. Further, at least the color correction of the color image sensor can be performed without changing the design of the filter portion of each color, the manufacturing conditions, and the adjustment, the design of the light receiving element, and the manufacturing process. It is possible to realize the associated reduction in time and cost.

In particular, as in the second aspect of the present invention, by using the layer of the adhesive used for bonding the color filters as the coloring layer, there is no need to remake the color filters, and the color filters once made Can be effectively utilized, and the cost and process time for remanufacturing the color filter can be shortened. When coloring the adhesive layer, pigment particles or dyes may be added for color adjustment as in the invention of claim 3, and after the color filter is manufactured, the color is changed to change the characteristics. When a correction process becomes necessary, it can be dealt with by simply changing the pigment or dye in the adhesive.

Further, as in the invention described in claim 4, by using the overcoat of the color filter as the coloring layer, it is possible to change the type, thickness, manufacturing conditions, etc. of the coloring material of each coloring film of the color filter. Therefore, it is possible to produce a color-corrected color filter with a minimum of changes in manufacturing conditions and in almost the standard process. Therefore, the sensitivity ratio can be adjusted with almost no increase in cost. As a result, the color of the color image sensor is corrected without changing the design of the colored film of the color filter or the manufacturing conditions, and the cost and time for adjusting the sensitivity ratio can be reduced. When coloring the overcoat, pigment particles or dyes for color adjustment can be added as in the invention of claim 5, and the sensitivity ratio of each color can be easily adjusted only by adjusting the pigments or dyes to be included. Since it can be adjusted to a desired value, it is possible to reduce the time and cost associated with color correction.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a color image sensor of the present invention.

FIG. 2 is a graph showing an example of a spectral transmittance curve of a color filter.

FIG. 3 is a graph showing an example of spectral sensitivity characteristics of a light receiving element.

FIG. 4 is a graph showing an example of light receiving sensitivity in an image sensor when an adhesive having high transmittance is used.

FIG. 5 is a graph showing an example of a spectral curve of a cyan color pigment.

FIG. 6 is a graph showing an example of a spectral transmittance curve when a colored layer mixed with a cyan pigment is provided.

FIG. 7 is a graph showing an example of light receiving sensitivity in an image sensor when an adhesive having high transmittance is used.

FIG. 8 is a cross-sectional view of an example of a color filter.

FIG. 9 is a flowchart illustrating an example of a color filter creating process.

[Explanation of symbols]

1 ... Image sensor substrate, 2 ... Electrode, 3 ... Amorphous Si layer, 4 ... ITO layer, 5 ... Colored film, 6 ... Adhesive, 7 ...
Au wire, 8 ... Si resin, 9 ... Color filter substrate, 10 ... IC, 11 ... Overcoat.

Claims (5)

[Claims] 1. A color image sensor comprising a color filter provided on a solid-state image sensor, wherein a color layer different from the color film of the color filter is provided on the solid-state image sensor, and the color balance of each color is achieved by the color layer. A color image sensor characterized by adjusting. 2. The color image sensor according to claim 1, wherein the colored layer is an adhesive used when the color filters are attached to each other. 3. The color image sensor according to claim 2, wherein the adhesive contains pigment particles or dyes for color adjustment. 4. The color image sensor according to claim 1, wherein the colored layer is an overcoat of the color filter. 5. The color image sensor according to claim 4, wherein the overcoat contains pigment particles or dyes for color adjustment.