JPH05199529A - Color imaging device - Google Patents

Abstract

(57) [Summary] [Purpose] The sensitivity of each color in a color linear sensor, etc.
Equalize. [Structure] Color fill on the upper surface of the sensor units 3R, 3G, 3B.
Color linear sensor with 1R, 1G, 1B
The thickness t of the color filters 1R, 1G, 1B._G, T _R, T
_BDepending on each color (t_G> T_R> T_B), Or color
Density ρ of the dye or pigment contained in the filter_G, Ρ_R, Ρ
_BChange (ρ_G> Ρ_R> Ρ_B) To equalize the sensitivity of each color
It

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image pickup device such as a color linear sensor.

[0002]

2. Description of the Related Art Conventionally, a color linear sensor includes, for example, a blue sensor array including a plurality of light receiving elements having a blue filter on the upper surface, and a red sensor array including a plurality of light receiving elements having a red filter on the upper surface. , A green sensor array including a plurality of light receiving elements having a green filter on the upper surface is arranged in parallel to each other, and a plurality of blue, red and green CCD structures corresponding to one side of each sensor array are arranged. It is configured to have a charge transfer register unit.

[0003]

In a conventional color linear sensor or the like, the sensitivities (output voltages) of red, green, and blue colors are different due to the difference in spectral characteristics of each color filter. Conventionally, the device has a spectral characteristic as shown in FIG. 5, and the sensitivity increases in the order of green (G), red (R), and blue (B). In FIG. 5, red (R) looks like the maximum, but in reality, since the infrared cut filter is inserted, green (G) becomes the maximum. Therefore, the saturated light amount is limited by the color signal having the highest sensitivity, and other color signals are disadvantageous in terms of S / N.

That is, for example, when green has the highest sensitivity and is used up to the saturation output voltage, more light cannot be used and blue, which is the least sensitive, can use only about 1/4 of the saturation output voltage. A very bad image quality is reproduced in terms of / N.

On the other hand, as a conventional method for equalizing the sensitivity differences of red, green, and blue caused by the spectral characteristics of each color filter, for example, there is a method of changing the area of the light receiving element of each color, that is, the sensor row, according to the sensitivity difference. is there.

However, in this method, the resolution in the sub-scanning direction (direction orthogonal to the direction of the sensor array) differs for each color, which causes deterioration of image quality.

In view of the above points, the present invention provides a color image pickup device in which the sensitivities of red, green and blue colors are equalized.

[0008]

According to the present invention, a sensor unit 3 is provided.
In the color image pickup device having the color filters 1B, 1R, 1G on the upper surfaces of B, 3R, 3G, the color filters 1B, 1
The film thickness of R and 1G is changed according to each color, and the sensitivity of each color is equalized.

Further, according to the present invention, the sensor portions 3B, 3R, 3
In a color imaging device having color filters 1B, 1R, 1G on the upper surface of G, the density of dyes or pigments included in the color filters 1B, 1R, 1G is changed according to each color, and the sensitivity of each color is equalized. To do.

[0010]

In the present invention, each color filter 1B, 1R,
The film thickness of 1G is changed according to each color, that is, the film thickness of the conventional color filter 1G having high sensitivity is set larger than the film thickness of the color filters 1R and 1B having low sensitivity.
By adjusting the spectral characteristics of R and 1G, the sensitivities (that is, output voltages) of the respective colors can be equalized. Therefore, each color signal output can be used up to around the saturated output voltage.

Further, in the present invention, each color filter 1
The density of the dye or pigment contained in B, 1R, and 1G is changed according to each color, that is, the conventional color filter 1G having high sensitivity.
The density of the dye or pigment of the color filter 1
Color filters 1B, 1R are made darker than those of R, 1B,
The sensitivity of each color can be equalized by adjusting the spectral characteristics of 1G. Therefore, also in this case, each color signal output can be used up to around the saturated output voltage.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case in which an embodiment of the present invention is applied to a color linear sensor will be described below with reference to the drawings.

In the present embodiment, in the color linear sensor, red, green, and
The sensitivity difference of each color of blue is equalized by the configuration of the color filter.

That is, in this example, as shown in FIG. 1, a blue sensor portion (that is, a sensor array) 3B including a plurality of light receiving elements 2B having a blue filter 1B on the upper surface and a red filter 1R are provided on the upper surface. A red sensor unit (that is, a sensor array) 3R including a plurality of light receiving elements 2R and a green filter 1G
A green sensor portion (that is, a sensor row) 3G including a plurality of light-receiving elements 2G each having an upper surface, and a sensor row 3B for each color,
Charge transfer register units 4B, 4R and 4G having a CCD structure corresponding to respective colors are arranged on one side of 3R and 3G.

Further, the charge transfer register sections 4B, 4
Output circuits 6B, 6R and 6G are connected to the final stages of R and 4G via floating diffusion portions 5B, 5R and 5G for converting signal charges into voltages, respectively.

However, in this example, each color filter 1B,
Regarding 1R and 1G, the film thickness of each color filter is increased in the order of higher sensitivity, and the higher sensitivity is controlled to equalize the sensitivity of each color.

That is, when the sensitivity is high in the order of green, red and blue,
As shown in FIG. 2, the film thickness t _G of the green filter 1G on the sensor unit 3G and the film thickness t of the red filter 1R on the sensor unit 3R have the spectral characteristics of the device as shown in FIG.
_R , the film thickness t _B of the blue filter 1B on the sensor unit 3B,
Set t _G > t _R > t _B.

According to this structure, the blue filter 1B,
The film thickness t _{B of} the red filter 1R and the green filter 1B,
By controlling each light transmittance by changing t _R and t _G so as to obtain the spectral characteristics of the device shown in FIG. 4, the sensitivity ratio of red and blue to green can be increased, and the sensitivity of each color can be increased. Can be equalized.

As a result, the saturated light amount of each color in the color linear sensor is equalized, each color signal output can be used up to near the saturated output voltage, and the image quality with good S / N can be reproduced.

Further, the light receiving elements 2R of red, green and blue are
Since the areas of 2G and 2B do not change, the resolution in the sub-scanning direction is the same for each color, and image quality does not deteriorate.

Further, as another embodiment, each color filter 1
Regarding B, 1R, and 1G, the densities of the dyes or pigments included in each filter are increased in order of the color having the highest sensitivity, and the sensitivities of the respective colors are equalized.

That is, when the sensitivity is higher in the order of green, red and blue,
As shown in FIG. 3, the thickness of each filter 1B, 1R, 1G is made constant so that the spectral characteristics of FIG. 4 are obtained, and the density ρ _G of the dye or pigment of the green filter 1G and the dye or pigment of the red filter 1R of The density ρ _R and the density ρ _B of the dye or pigment of the blue filter 1B are set to ρ _G > ρ _R > ρ _B.

According to this structure, the blue filter 1B,
By changing the densities ρ _B , ρ _R , and ρ _G of the dyes or pigments of the red filter 1R and the green filter 1G to control the respective light transmittances, the spectral characteristics of the device of FIG. 4 can be obtained. Similar to the case, the sensitivity of each color can be equalized. Therefore, the saturated light amount of each color in the color linear sensor is equalized, each color signal output can be used up to near the saturated output voltage, and the image quality with good S / N can be reproduced. Further, the resolution in the sub-scanning direction is also the same for each color, and good image quality can be obtained.

In FIG. 1, the sensor rows 3B, 3R, and
Although it is applied to a color linear sensor provided with 3G, although not shown in the figure, three charge transfer units 4R, 4R, are provided for one sensor row in which red, green, and blue light receiving elements are arranged in a dot-sequential manner.
It can also be applied to a color linear sensor of a system in which 4G and 4B are arranged.

Furthermore, the present invention is not limited to the linear sensor and can be applied to other color image pickup devices.

[0026]

According to the color image pickup apparatus of the present invention, the sensitivity of each color is made uniform by changing the thickness of each color filter according to the sensitivity difference of each color or by changing the density of the dye or pigment contained in each color filter. Can be converted. Therefore, each color signal output can be used up to around the saturated output voltage, and an image quality with good S / N can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color linear sensor according to the present invention.

FIG. 2 is a sectional view of an essential part showing an example of the present invention.

FIG. 3 is a cross-sectional view of a main part showing another example of the present invention.

FIG. 4 is a spectral characteristic diagram of a device obtained by the color linear sensor of the present invention.

FIG. 5 is a spectral characteristic diagram of a device obtained by a conventional color linear sensor.

[Explanation of symbols]

 1R, 1G, 1B Color filter 2R, 2G, 2B Light receiving element 3R, 3G, 3B Sensor section 4R, 4G, 4B Charge transfer register section 5R, 5G, 5B Floating diffusion section 6R, 6G, 6B Output circuit

Claims (2)

[Claims] 1. A color imaging device having a color filter on the upper surface of a sensor section, wherein the film thickness of the color filter is changed according to each color to equalize the sensitivity of each color. 2. A color image pickup device having a color filter on the upper surface of a sensor section, wherein the density of dyes or pigments contained in the color filter is changed according to each color to equalize the sensitivity of each color.