JPH04172861A - Color image sensor and color picture reading method - Google Patents

Abstract

PURPOSE:To obtain a color image sensor which is high in reliability and sensitivity by providing plural photodetector and plural wavelength converting members. CONSTITUTION:Wavelength converting members 28a-28c respectively convert R-, G-, and B-wavelength components into components having wavelengths lambda1-lambda3. The R-wavelength component of the signal light 33 reflected by an original after passing through glass substrate 21, transparent insulating layer 27, protective layer 29, and cover glass 30 is converted into a component having a wavelength around lambda1 by means of the member 28a and read our from an individual electrode 22 as R-signals after the component is accumulated in a photodetector 23a through the insulating layer 28 and a transparent electrode 25a. Similarly, G-and B-signals are obtained by respectively converting the G-and B-components of the light 33 into components having wavelengths around lambda2 and lambda3 and supplying the converted components to photodetectors 23b and 23c.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to the structure of a color image sensor for reading color images and the method for reading color images. [Prior Art] Conventionally, color images are read. The color image sensor for this purpose has a configuration in which a transmissive color filter is attached to an image sensor for reading monochrome images, and by receiving the image signal light through the transmissive color filter, it is possible to detect red (R), green, etc. It was separated into three colors: (G) and blue (B).

[Problems to be Solved by the Invention] However, the conventional color image sensor requires a process of bonding the color filter to the image sensor body with high precision. The process of bonding color filters together is carried out manually by an operator while observing through a microscope, which increases costs and reduces yield. This means that the increase in the number of pixels is strong (
In today's world, it cannot be ignored.

Furthermore, in conventional color image sensors, the spectral sensitivity of the light-receiving element is not configured to increase the maximum sensitivity for each color to be separated; for example, R, G, B
When separating the light into the three colors, - boat fishing has low sensitivity to blue, which causes various problems in the circuit configuration or the configuration of the light receiving element.

Furthermore, conventional transmissive color filters suffer from changes over time such as fading and peeling off from the image sensor body, resulting in a decrease in reliability.

The present invention is intended to solve the above-mentioned problems, and aims to provide a color image sensor and a color image reading method that are inexpensive, highly sensitive, and highly reliable.

[Means and effects for solving the problems] FIG. 1 shows the basic configuration of a color image sensor and a color image reading method of the present invention. Note that FIG. 1 is a diagram showing a cross section in the sub-scanning direction, and shows a configuration example in which three rows of sensors are provided along the sub-scanning direction.

As shown in FIG. 1, the color image sensor of the present invention is on the path of the signal light 6 reflected by the original 4,
Further, wavelength conversion members 3a, 3b, and 3c are provided at positions close to the light receiving elements 2a, 2b, and 2c, respectively. Here, the wavelength conversion members 3a, 3b, 3c each have a spectral sensitivity in a specific wavelength range of the signal light 6, and each of these wavelength components is converted into a spectral sensitivity within the spectral sensitivity of the corresponding light receiving element 2a, 2b, 2c. It converts into the wavelength component of the phosphor, 2
It consists of something that can convert one wavelength component into a different wavelength component, such as a photon absorber or nonlinear optical material.

Now, for example, the spectral sensitivities of the light receiving elements 2g, 2b, and 2c are all the same, as shown by 10 in FIG. 2(b),
Assuming that the quantum efficiencies of the wavelength conversion members 3a, 3b, and 3c are as shown by 9a, 9b, and 9c in FIG. 2(a), respectively, the wavelength conversion member 3a is shown by 98 in FIG. 2(a). The wavelength component is converted into a wavelength component indicated by 11 in FIG. 2(b). It is clear that the wavelength component 11 is within the spectral sensitivity of the light receiving element 2a indicated by 10 in FIG. 2(b). The signal light 7a whose wavelength has been converted by the wavelength conversion member 3a enters the light receiving element 2a, and is output as an electrical signal from an extraction electrode (not shown). light receiving element 2b,
The same applies to 2c.

This allows the light receiving elements 2a, 2b, and 2c to be used at maximum sensitivity. Note that the material of the wavelength conversion member to be used is determined by taking into consideration the wavelength component to be obtained and the spectral sensitivity of the light receiving element.

Note that the close position refers to the wavelength conversion members 3a, 3b.
, 3c wavelength-converted signal light 7 m + 7 b +
7c means a position where the light can be incident on the light receiving elements 2m, 2b, 2c, and includes the position where the light is in close contact with the light receiving elements 2a, 2b, 2c, as well as the position where the light is far away as shown in Fig. 1. This also includes the vicinity of the light receiving elements 2a, 2b+2c.

In addition, in FIG. 1, 1 indicates a glass substrate, and 8 indicates a transparent body.

In the above description, the sensor rows are arranged in the sub-scanning direction, but it goes without saying that they may be of a so-called in-line type. Further, although each wavelength conversion member has been described as one that converts the wavelength into the same wavelength component, it is also clear to those skilled in the art that it may convert into different wavelength components.

[Example code] Examples will be described below with reference to the drawings.

FIG. 3 is a sectional view showing the structure of an embodiment in which the color image sensor and color image reading method according to the present invention are applied to a contact type image sensor, in which 21 is a glass substrate, 22 is an individual electrode. , 23g, 23b, 23c
is a light receiving element, 24 is a light shielding insulating layer, 25a, 25b, 25
c is a transparent electrode, 2 f3 a, 26 b, 28 c are common electrodes, 27 is a transparent insulating layer, 28 a, 28 b 128 c
is a wavelength conversion member, 29 is a protective layer, 3o is a cover glass,
31 is a document, 32 is an illumination light, and 33 is a signal light.

In FIG. 3, three light-receiving element rows, an element row of light-receiving elements 23a, an element row of light-receiving elements 23b, and an element row of light-receiving elements 23c, are arranged along the sub-scanning direction of the original 31, and the conventional color An image sensor has spectral sensitivity to specific wavelength components corresponding to each of the light receiving elements 23a, 23b, and 23c, instead of a transmission color filter,
and a wavelength conversion member 28a that converts the wavelength component into a wavelength component within the spectral sensitivity of each corresponding light receiving element;
28b.

It is different in that it is equipped with 28c. That is, for example,
The wavelength conversion member 28a is sensitive to the wavelength component of R and converts the wavelength component into a wavelength component having the wavelength λ as the center wavelength, and similarly the wavelength conversion member 28b.

28c is sensitive to the G and H wavelength components, respectively, and converts the corresponding wavelength components into wavelengths λ2. When converting to a wavelength component with λ2 as the center wavelength, the glass substrate 21, the transparent insulating layer 27,
Among the wavelength components of the signal light 33 obtained by transmitting through the protective layer 29 and the cover glass 30 and being reflected by the original 31, the R wavelength component is converted into a wavelength component with the wavelength λ1 as the center wavelength by the wavelength conversion member 28a. The light is converted, passes through the transparent insulating layer 27 and the transparent electrode 25a, enters the light receiving element 23a, and undergoes photoelectric conversion. The charge stored in the light receiving element 23a is then read out as an electrical signal from the individual electrode 22 and used as an R signal. Similarly, among the wavelength components of the signal light 33, the G and B wavelength components are converted into wavelength components whose center wavelength is λ3 by the wavelength conversion members 28b and 28c, respectively. 27, transparent electrode 25
The light passes through the light receiving elements 23b and 23c and undergoes photoelectric conversion, is read out from the individual electrode 22 as an electrical signal, and is used as a G signal and a B signal.

As described above, three primary color signals of R, G, and H are generated. Note that the center wavelength λ1゜λ2. after wavelength conversion. λ
The light-receiving elements 23a and 2 are usually
Since 3b and 23c are made of the same material, λ1=λ
Wavelength conversion materials 28a, 28b, 2 so that 2=λ3
It is recommended to select 8c. In this case, the wavelength conversion members 28a, 28b, 28c and the transparent electrodes 25a, 25
The insulating layer formed between b and 25c is λ.

It is possible to use a material that is transparent only to nearby wavelengths and opaque to other wavelength components, especially the wavelength component of the illumination light 32. By doing this, unnecessary wavelength components that become noise components can be eliminated. Can be removed.

Furthermore, in the configuration shown in FIG. 3, the wavelength conversion member 28a
, 28b, and 28c can be formed by a well-known photolithography process.

Although one embodiment of the present invention has been described above, it will be appreciated by those skilled in the art that the present invention is not limited to the above embodiment, and that various modifications can be made, and that an in-line color image sensor can also be configured in the same way. it is obvious.

[Effects of the Invention] As is clear from the above description, according to the present invention, transmissive color filters are not pasted together as in conventional color image sensors, so color filter pasting is not a tedious process. Not only can this process be omitted, but it is also possible to avoid deterioration in reliability due to fading, peeling, etc. of the color filter, which has been a problem in the past.

Furthermore, by appropriately selecting the wavelength conversion material, it is possible to use a photodetector with any spectral sensitivity.For example, a photodetector with high sensitivity to near-infrared light using gallium-arsenide can be used to produce highly sensitive color. The degree of freedom in design can be increased, such as by being able to configure an image sensor.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the basic configuration of a color image sensor and color image reading method according to the present invention, FIG. 2 is a diagram for explaining wavelength conversion by a wavelength conversion member, and FIG. 3 is a color image according to the present invention. 1 is a cross-sectional view showing the configuration of an embodiment of a sensor and a color image reading method. DESCRIPTION OF SYMBOLS 1... Glass substrate, 2a, 2b, 2c... Light receiving element, 3m, 3b, 3c... Wavelength conversion member, 4... Original, 5... Illumination light, 6... Signal light 1 7m+7b+7
c...Wavelength converted signal light, 8...Transparent body, 21
... Glass substrate, 22 ... Individual electrode, 23 a +
23 b + 23 c・” Light-receiving element, 24-・Light-shielding insulating layer, 25 a, 25 b, 25 c---Transparent electrode, 26m, 2θb, 26cm--Common electrode, 27-・
・Transparent insulating layer, 28m, 28b, 28c... Wavelength conversion member, 29... Protective layer, 30... Cover glass, 3
1... Original, 32... Illumination light, 33... Signal light. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) Multiple light-receiving elements and light-receiving elements that are placed on the path of the signal light to the light-receiving element and in close proximity to the light-receiving element, and that correspond to a predetermined wavelength component of the signal light, have different spectral sensitivities. A color image sensor comprising a plurality of types of wavelength conversion members that convert into wavelength components. (2) A color device characterized in that a plurality of mutually different wavelength components of signal light obtained by illuminating an image are wavelength-converted into wavelength components within the spectral sensitivity of each light-receiving element, and are made incident on the light-receiving element for reading. Image reading method.