JPS6182468A - Color image sensor - Google Patents

Abstract

PURPOSE:To obtain a color image sensor which has high resolution, increases the wiring density on a substrate and has no irregular photosensitive area by forming at least three rows of photoelectric converter rows for sensing color lights by utilizing both side surfaces of the transparent substrate. CONSTITUTION:The first photoelectric converter row 11 is formed on the first surface 10a of a transparent substrate 10, and made of individual Cr electrodes 14 divided and forming a main scanning direction at every element, an amorphous silicon film 15, and a common ITO transparent electrode 16. Strip color filters 17, 18 are formed at the positions corresponding to the regions of the second and third photoelectric converter rows 12, 13. The rows 12, 13 are formed of individual ITO transparent electrodes 18, 20, an a-Si:Ge:H film 21 and common electrodes 22, 23 on the second surface 10b of the substrate 10. The color separation is performed in the direction perpendicular to the arraying direction of the photoconverter rows, and the resolution is not different from the case of reading out monochromatic image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color image sensor, and particularly to a color image sensor having a structure suitable for use in a long length using an amorphous semiconductor film.

[Technical background of the invention and its problems]

2. Description of the Related Art As a device for reading images on a document, a long image sensor called a contact image sensor using an amorphous silicon film, which can easily be made into a large area, is being actively developed. The typical structure of such an image sensor is
Metal electrodes such as Qr as individual electrodes divided for each element on the substrate.

Hydrogenated amorphous silicon, IT as a common electrode
A photoelectric conversion element array (photodiode array) is formed by sequentially laminating transparent electrodes made of O films, etc., and the structure is such that light enters from the transparent electrode side and photocurrent is extracted through the gold fi electrode. There is.

An image sensor with such a structure is suitable for reading a monochromatic umbrella, but when trying to read a color image, it requires at least three times as many pixels, resulting in a problem that the resolution is reduced by 8 degrees. To solve this problem, color separation should be performed not in the main scanning direction (the direction in which the photoelectric conversion element rows are arranged) but in a direction perpendicular to this direction, that is, in the sub-scanning direction.

However, in order to perform color separation in the sub-scanning direction, it is necessary to form at least three photoelectric conversion element rows close to each other, which increases the convexity of the arrangement of the lead wiring from the metal electrode, making it difficult to manufacture the image sensor. becomes difficult, and a decrease in yield becomes unavoidable. In addition, in the inner photoelectric conversion element array, it is necessary to pass lead wiring for the outer photoelectric conversion element array between adjacent elements, so that the electrode area, that is, the photosensitive area, is smaller than that of the outer photoelectric conversion element array. A problem arises in that it is lower than that of the element array.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a color image sensor that has high resolution and is free from increased wiring density on a substrate and non-uniformity in photosensitive area.

[Summary of the invention]

The color image sensor according to the present invention has a transparent substrate.
At least one row of photoelectric conversion elements sensitive to a predetermined color light is formed on the second surface, and each row of photoelectric conversion elements sensitive to color light different from the color light to which the photoelectric conversion element rows on the first surface are sensitive is formed on the second surface. At least two rows of photoelectric conversion elements are formed adjacent to the row of photoelectric conversion elements on the first surface, and the first and second rows are formed adjacent to the photoelectric conversion element row on the first surface.
It is characterized in that either one of the surfaces is used as a light entrance surface.

Here, the photoelectric conversion element array is constructed by sandwiching, for example, an amorphous semiconductor film between a metal electrode and a transparent electrode. In this case, the amorphous semiconductor films on the first and second surfaces are formed so as to overlap at least at a position corresponding to the photoelectric conversion element array region on the surface opposite to the light incidence surface, and By making the forbidden band width of the amorphous semiconductor film larger than the forbidden band width of the amorphous semiconductor film on the side opposite to the light incidence surface, the light of the wavelength transmitted through the amorphous semiconductor film on the side of the light incidence surface is transferred to the side opposite to the light incidence surface. If the amorphous semiconductor film absorbs the light, it is possible to separate the colored light to which the photoelectric conversion element array on the first surface is sensitive and the colored light to which the second photoelectric conversion element array is sensitive.

Therefore, by adding a color filter that separates the colored light to which at least two rows of photoelectric conversion element rows on the second surface are sensitive, it is possible to separate the color light (both three colors) for reading a color image. It is possible to do so.

〔Effect of the invention〕

According to the present invention, since at least three rows of photoelectric conversion elements sensitive to each color light are formed using both sides of a transparent substrate, color images can be read without the inconveniences of the conventional method. .

That is, in the present invention, since the photoelectric conversion element arrays sensitive to each color light are arranged in parallel, color separation is performed in a direction perpendicular to the arrangement direction of the photoelectric conversion element arrays, and the resolution is higher than that of a monochromatic image. It's no different than when reading. Also,
Since there may be one or two rows of photoelectric conversion element rows on both the first and second surfaces of the substrate, the density of lead wiring from individual electrodes divided for each element of the photoelectric conversion element row does not particularly increase. . Furthermore, since there is no need to run the lead wiring from the individual electrodes between the elements of the photoelectric conversion element array, it is possible to equalize the electrode area of the individual electrodes, that is, the substantial photosensitive area, and as a result, When visual recording or the like is performed on the original image from the image reading output, it is possible to obtain a color image with good color reproducibility.

[Embodiments of the invention]

FIG. 1 shows the configuration of a color image sensor according to the first embodiment of the present invention, in which (a) is a plan view and (b) is a plan view.
-A sectional view.

In the figure, the transparent substrate 10 is, for example, a glass substrate,
A first photoelectric conversion element array 11 is formed on the first surface 10a, and second and third photoelectric conversion element arrays 12, 13 are formed on the second surface 10b.

The first photoelectric conversion element array 11 includes gold R electrodes 14 made of Cr or the like as individual electrodes formed on the first surface 10a of the transparent substrate 10 and divided in the main scanning direction for each element;
Thereon, a hydrogenated amorphous silicon film 15 is uniformly formed at positions corresponding to the regions of the first to third photoelectric conversion element rows 11 to 13, and a first photoelectric conversion element on this amorphous silicon film 15 is formed. It consists of a transparent electrode 16 made of ITO or the like as a common electrode selectively formed in a band shape at a position corresponding to the area of the row 11.

Furthermore, on the amorphous silicon film 14, strip-shaped color filters 17.18 are further disposed adjacent to both sides of the transparent electrode 16, that is, at positions corresponding to the areas of the second and third photoelectric conversion element rows 12.13. It is formed.

On the other hand, the second and third photoelectric conversion element arrays 12°13 are
ITO or the like is used as individual electrodes that are located on both sides of the metal electrodes 14 in the first photoelectric conversion element array 11 on the second surface 10b of the transparent substrate 10 and are formed separately in the main scanning direction for each element. The transparent electrode 19.20, the amorphous silicon film 21 formed thereon, and the amorphous silicon film 121 are selectively formed in a band shape at positions corresponding to the regions of the first and second photoelectric conversion element rows 12.13. Metal electrode 22.2 made of Cr or the like as a common electrode
It consists of 3.

Here, the first surface 10a of the transparent substrate 1o is the incident side of light such as reflected light from the document surface, and the amorphous silicon film 15 on this light incident surface side is made of a-
8i:C:Hli, and on the other hand, the amorphous silicon 11!21 on the opposite side to the light incident surface becomes an a-8i:Ge:)-1 film by mixing Ge, for example. In this case, the forbidden band widths of the a-8i:C:H film 15 and the a-8i:Ge:H film 21 become as shown in FIGS. 2(a) and 2(b), respectively, with the former being larger. That is, from the incident light α shown in FIG. 3(a) to a-3i
:C: Hllll 5 is a relatively high energy photon, that is, light on the short wavelength side (as shown in Figure 3(b)).
absorbs blue light) β and transmits the transmitted light Y to a-8 (:Ge
: Make it absorb with HII21. However, on the light incidence side, the 213rd and third photoelectric conversion element arrays 12.1
Since the color filters 17 and 18 are provided at positions corresponding to the regions 3 and 3, the a-5i:Ge:H 1121 is actually the third region of the transmitted light γ of the a-3i:Q:)l film 15. Green light δ separated by color filters 17 and 18 as shown in Figure (C).

It will absorb red light ε.

In this way, the image output corresponding to blue light is transmitted by the first photoelectric conversion element array 11 to the second photoelectric conversion element array 12.
By this, an image output corresponding to green light can be obtained, and by the third photoelectric conversion element array 13, an image output corresponding to red light can be obtained. Note that these image outputs are produced by the metal electrode 14. It is taken out from the transparent electrode 19.20 via the drawer arrangement 14a (14b), 19a, 20a.

According to this embodiment, as is clear from the figure, the gold jI electrodes 14, which are the individual electrodes in the first photoelectric conversion element array 11,
．． For both of the transparent electrodes 19°2o, which are individual electrodes in the second and third photoelectric conversion element rows 12.13, the arrangement density of the electrodes may be the same as in the case of reading a monochromatic image in which individual electrodes are arranged in one row. There is no deterioration in resolution. Furthermore, the density of the lead wires 14a, 14b, 19a, and 20a is also about the same as in the case of reading a monochrome image, and there is no particular problem in manufacturing even if the density of the individual electrodes is increased. Furthermore, each electrode 1
Since the areas of 4, 19.20 can be made equal,
1m picture with good color balance! 5! output is obtained.

In the above embodiment, the amorphous silicon 1 on the light incident surface side
115 is provided in a range that covers the entire area of the first to third photoelectric conversion element arrays 11 to 13, but the transparent electrode 16 is provided at a position corresponding to the area of the first photoelectric conversion element array 11, that is, in the figure. It may be formed only directly below. but,
Generally, if the amorphous silicon film 15 on the light incident surface side absorbs the necessary and sufficient amount of light, this amorphous silicon ff1l15 will not block the light that enters the amorphous silicon 1II21 on the opposite side to the light irradiation surface. , amorphous silicon [115] may be formed as shown in FIG. 1 without any problem.

FIG. 4 shows a second embodiment of the present invention, in which a color filter 41 (according to the above explanation, a blue light transmitting filter is used) is formed on the transparent electrode 16 in FIG. 1 for color separation. This is done more reliably. Further, in this embodiment, the three gold electrodes 22 and 23 in FIG. 1 are used in common, and a metal electrode 42 made of Cr or the like is formed almost entirely on the amorphous silicon film 21.

In the third embodiment shown in FIG. 5, the second surface 10b side, which is the surface on which the two photoelectric conversion element rows 12 and 13 of the transparent substrate 10 are formed, is used as the light incident surface. . That is, the first layer formed on the first surface 10a of the transparent substrate 10
The individual electrodes in the photoelectric conversion element rows 11 are made of transparent electrodes 51 made of ITO or the like, and the amorphous silicon film 52 is used as the individual electrodes in the second and third photoelectric conversion element rows 1 in the first embodiment.
For example, an a-8i :Qe :)l film having absorption characteristics similar to those used in 2.13 is used, and the common electrode is a metal electrode 53 made of Cr or the like.

On the other hand, in the second and third photoelectric conversion element arrays 12.13 formed on the second surface 10b, the amorphous silicon film 54 is used in the first photoelectric conversion element array 11 in the embodiment of FIG. A transparent electrode 55 made of ITO or the like is formed as a common electrode on almost the entire surface of this amorphous silicon film 54. Then, color filters 56 and 57 are formed on the transparent electrode 55 at positions corresponding to the areas of the second and third photoelectric conversion element rows 12 and 13, and more preferably, in order to ensure color separation,
Photoelectric conversion element array 11. It is clear that similar effects can be obtained in the area of

Note that the amorphous silicon film 52 in FIG. 5 does not need to have a position corresponding to the area of the second and third photoelectric conversion element rows 12.degree. 13, that is, a portion below the color filters 56 and 57.

In the fourth embodiment shown in FIG. 6, a transparent electrode 61 formed on the second surface 10b of a transparent substrate 10 is used as a common electrode, and metal electrodes 62 and 63 are used as individual electrodes. Note that although the transparent electrode 61 is common to the second and third photoelectric conversion element arrays 12 and 13 in the figure, it may be separated between them.

Furthermore, a portion of the amorphous silicon film 21 corresponding to the region of the first photoelectric conversion element 11 may be removed.

These embodiments also provide the same effects as described above.

Although several embodiments of the present invention have been described above, the present invention is not limited thereto, and includes a total of at least three rows of photoelectric conversion elements each sensitive to different colored light arranged close to each other on both sides of a transparent substrate. Various modifications can be made without departing from the gist of the present invention. For example, in addition to the photoelectric conversion element arrays sensitive to three colored lights, a photoelectric conversion element array sensitive to white light may be added to form a total of four photoelectric conversion element arrays, two rows on each side of the transparent substrate. .

Further, in the embodiment, a means (shadow mask) for shielding the non-photosensitive region of the amorphous silicon film (for example, a region facing the lead wiring) from light is omitted, but these can be provided as appropriate. In addition, by devising the shape of the lead wiring of the metal electrode made of Cr or the like in the photoelectric conversion element array formed on the light incidence surface side, for example, the individual electrodes in the photoelectric conversion element array formed on the opposite side to the light incidence surface can be drawn out. The step of forming a shadow mask can be omitted or simplified by forming it so as to overlap with the wiring or by forming it at a position facing another area that cannot be exposed to light.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a plan view and a sectional view taken along line A-A of a color image sensor according to a first embodiment of the present invention, and FIGS. 2(a) and 2(b) are light incident sides of the same embodiment. FIGS. 3(a) to 3(C) are diagrams showing the relationship between the forbidden band width of the amorphous silicon film on the opposite surface and the relationship between the forbidden band width of the amorphous silicon film on the opposite surface. 4(a) and 4(b) are a plan view and a sectional view taken along line 8-8 of a color image sensor according to a second embodiment of the present invention, and FIGS. 4 is a cross-sectional view of a color image sensor according to Example 4. FIG. 10...Transparent substrate, 10a, 10b...1st. Second
11 to 13...first to third photoelectric conversion element rows,
14.22.23.42.53.62.63... Gold a
Electrode, 15.21.52.54...Amorphous silicon film, 16.19,20.52.55.61...Transparent electrode, 17.18.41.56.57゜58...Color filler . Applicant's agent Patent attorney Takehiko Suzue Figure 2 (α) (b) 3rd! ″ Figure 4

Claims (9)

[Claims] (1) At least one row of photoelectric conversion elements sensitive to predetermined colored light is formed on the first surface of the transparent substrate, and colored light to which the photoelectric conversion element rows on the first surface are sensitive is formed on the second surface. At least two rows of photoelectric conversion elements each sensitive to light of a different color are formed adjacent to the row of photoelectric conversion elements on the first surface, and either one of the first and second surfaces is exposed to light. A color image sensor characterized by having an incident surface. (2) The color image sensor according to claim 1, wherein the photoelectric conversion element array is constructed by sandwiching an amorphous semiconductor film between a metal electrode and a transparent electrode. (3) The amorphous semiconductor films on the first and second surfaces are formed so as to overlap at least at a position corresponding to the photoelectric conversion element array region on the surface opposite to the light incidence surface side, and By making the forbidden band width of the amorphous semiconductor film larger than the forbidden band width of the amorphous semiconductor film on the side opposite to the light incidence surface, the light of the wavelength that has passed through the amorphous semiconductor film on the side of the light incidence surface can be transferred to the side opposite to the light incidence surface. 3. The color image sensor according to claim 2, wherein the color image sensor absorbs the light through an amorphous semiconductor film. (4) A metal electrode selectively formed on the first surface at a position corresponding to the photoelectric conversion element array area on the first surface, corresponding to the photoelectric conversion element array area on the first and second surfaces. an amorphous semiconductor film formed at a position corresponding to the photoelectric conversion element array area on the first surface of the amorphous semiconductor film, a transparent electrode selectively formed at a position corresponding to the photoelectric conversion element array area on the first surface of the amorphous semiconductor film, and a transparent electrode corresponding to the photoelectric conversion element array area on the second surface of the amorphous semiconductor film. color filters that are selectively formed at the respective positions and transmit mutually different color light are sequentially laminated, and transparent electrodes are selectively formed on the second surface at positions corresponding to the photoelectric conversion element array areas on the second surface. , an amorphous semiconductor film formed at a position corresponding to the photoelectric conversion element array region on at least the second surface, and a metal electrode formed at a position corresponding to the photoelectric conversion element array region on at least the first and second surfaces. Claims 1, 2, or 3 are characterized in that they are sequentially laminated, and the first surface side is the light incident surface.
Color image sensor described in section. (5) A color filter is formed on the transparent electrode formed on the first surface to transmit a color light different from that transmitted by the color filter formed on the amorphous semiconductor film on the first surface. A color image sensor according to claim 4, characterized in that: (6) A transparent electrode selectively formed on the first surface at a position corresponding to the photoelectric conversion element array area on the first surface, at least a position corresponding to the photoelectric conversion element array area on the first surface. The amorphous semiconductor film formed on the first surface is sequentially laminated with metal electrodes selectively formed at positions corresponding to the photoelectric conversion element array region on the first surface, and the photoelectric conversion element array region on the second surface is sequentially laminated. a metal electrode selectively formed at a position corresponding to the conversion element array region; an amorphous semiconductor film formed at a position corresponding to the photoelectric conversion element array region on the first and second surfaces; and at least a second semiconductor film of the amorphous semiconductor film. Claims characterized in that color filters formed at positions corresponding to the photoelectric conversion element row regions on the surface and transmitting different colored light are sequentially stacked, and the second surface side is the light incident surface. 1st
2. The color image sensor according to item 2, item 3, or item 3. (7) A metal electrode selectively formed on the first surface at a position corresponding to the photoelectric conversion element array area on the first surface, corresponding to the photoelectric conversion element array area on the first and second surfaces. an amorphous semiconductor film formed at a position corresponding to the photoelectric conversion element array area on the first surface of the amorphous semiconductor film, a transparent electrode selectively formed at a position corresponding to the photoelectric conversion element array area on the first surface of the amorphous semiconductor film, and a transparent electrode corresponding to the photoelectric conversion element array area on the second surface of the amorphous semiconductor film. a transparent electrode formed on the second surface at least at a position corresponding to the photoelectric conversion element array area on the second surface; An amorphous semiconductor film formed at a position corresponding to the photoelectric conversion element array region on at least the second surface and a metal electrode selectively formed at a position corresponding to the photoelectric conversion element array region on the second surface are sequentially laminated. The color image sensor according to claim 1, 2 or 3, wherein the first surface side is a light incident surface. (8) A color filter is formed on the transparent electrode on the first surface to transmit a color light different from that transmitted by the color filter formed on the amorphous semiconductor film on the first surface. A color image sensor according to claim 7. (9) The lead wiring of the metal electrode formed on the light incident side of the first and second surfaces cannot be exposed to the amorphous semiconductor film formed on the surface opposite to the light incident side. Claims 2, 3, 4, 5, 6, and 7 are characterized in that the area is formed to block light.
9. The color image sensor according to item 8.