JPH02230862A - Picture reader - Google Patents

Abstract

PURPOSE:To improve the resolution of picture reading by interposing an insulation member between a photodetector and an original face, forming a transparent part to the insulation member placed on each picture element of the photodetector and forming the transparent part to the insulation member including a face sectioning the transparent part mutually. CONSTITUTION:An insulation member 500 consists of a light transmission part 51 transmitting a light and a light shield part 52 shutting light. The light transmission part 51 is placed in each picture element 101 of a photodetector 100 and formed as a square cylindrical body with equal cross sectional area to that of the picture element 101. The insulation member 500 except the light transmission part 51 forms the light shield part 52. Moreover, each light shield part 52 is formed to shield each light transmission part 51. Thus, only a reflected light from an original face placed just above the photodetector 100 is made incident into each picture element, the reflected light from the other part of the original face is shut by the light shield part 52 and not made incident into the picture element, then the resolution of the photodetector 100 is improved.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to an image reading device used in facsimiles, scanners, etc., and in particular to improving the resolution of a light receiving element constituting the reading section of an image reading device. It is related to the structure of

(Prior Art) Conventionally, contact type image reading devices used in facsimile machines, scanners, etc. have a light source such as a fluorescent lamp, a light receiving element having the width of the document, and an image of reflected light from the document on the light receiving element. It consists of a convergent light guide system that stores optical signals from reflected light from the original according to the density as electrical signals in light receiving elements arranged in an array by electrical scanning, and transmits these electrical signals in time series. It is used to output an image signal. According to this image reading device, the size of the device can be reduced compared to a method using a reduction optical system, but since an expensive rod lens array or the like is used as the convergent light guiding system, There is a drawback that there is a limit to the reduction in price and that it takes time and effort to adjust the focus between the light guide system and the sensor light receiving surface.

Therefore, in order to reduce the size and cost of the device, an image reading device using a so-called full contact type image sensor, in which a converging light guide system is formed on the sensor substrate surface without using a rod lens array, has been proposed. There is.

This image reading device includes a light receiving element 100 formed on an insulating substrate 10, as shown in FIGS. 10 and 11, for example.
and a light source (not shown) such as a fluorescent lamp or an LED array arranged on the back side of the insulating substrate 10. Light receiving element 100
is constructed by sequentially forming individual electrodes 11, a band-shaped photoconductive layer 12, and a band-shaped common electrode 13, which are arranged discretely in the main scanning direction, and the individual electrodes 11. Photoconductive layer 12, common electrode 13
The overlapping portions form pixels 101, which serve as a plurality of photoelectric conversion elements arranged in a line in an array. Further, the light receiving element 100 is covered with a transparent protective layer 14 and a transparent wear-resistant layer 15. A light passage window 16 is formed on the side of the light receiving element 100 in the sub-scanning direction to guide light from a light source placed on the back side of the insulating substrate 10 to the side of the document 200 placed on the light receiving element 100.

According to the image reading device as described above, light emitted from the light source is irradiated onto the document 200 placed on the transparent wear-resistant layer 15 through the light passing window 16, and the reflected light 300 is incident on the pixel 101 of the light receiving element 100. do.

(Problems to be Solved by the Invention) However, the structure of the image reading device described above does not include a light guide system that focuses the light reflected from the document surface onto the light receiving element, so there are the following problems. Ta.

That is, the pixel 101a of the light receiving element 100 has the pixel 1
Not only the reflected light 300 guided from the document surface AO corresponding to one pixel that 01a should be read, but also unnecessary reflected light 400 from the document surface A corresponding to one pixel adjacent thereto is irradiated. Therefore,
In the pixel 101a, charge is accumulated for the total amount of reflected light 300 and unnecessary reflected light 400, so the pixel 101a
The electrical signal outputted from 01a is a combination of image information on document surface AO and image information on document surface A, which overlap each other. The amount of charge accumulated in the pixel 101a due to the irradiation of the unnecessary reflected light 400 is compared to that caused by the reflected light 300 because the optical path length of the reflected light 400 from the document surface A to the pixel 101a is long and the angle of incidence is large. If so, the value is small. However, if the original surface A, is white, the original surface A,
The reflected light 400 from the pixel 101a has a strength that affects the pixel 101a, leading to a decrease in the resolution (MTF) of the light receiving element 100.

In particular, as the original 200 floats from the transparent wear-resistant layer 15, reflected light from a surface other than the original surface that should be read by one pixel is more likely to enter the pixel 101a that reads one pixel of the original surface, resulting in a deeper depth of focus. The problem was that it was structurally difficult.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an image reading device that can improve the resolution of image reading while reducing the size and cost without using a light guide system. (Means for Solving the Problem) In order to solve the problems of the conventional example described above, an image reading device of the present invention has a light receiving element and a light source, and the light source is placed on the document surface located above the light receiving element. In an image reading device that irradiates light from a source and makes the reflected light enter the light receiving element, an insulating member is interposed between the light receiving element and the document surface, and the insulating member is located on each pixel of the light receiving element. The present invention is characterized in that a light-transmitting portion is formed in the member, and a light-blocking portion is formed in the insulating member including a surface that separates the light-transmitting portion from each other.

(Function) According to the present invention, only the reflected light from the document surface located directly above enters each pixel of the light-receiving element, and the reflected light from other parts of the document surface is blocked by the light shielding part, and the pixel There is no incident on the

(Example) An example of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory cross-sectional view of an image reading device according to an embodiment of the present invention, and parts having the same configuration as in FIG. 10 are designated by the same reference numerals.

This image reading device includes a light receiving element 100 on an insulating substrate 10.
An insulating member 500 is disposed on the light receiving element 100, and a transparent wear-resistant layer 15 made of a glass plate or the like is further formed on the insulating member 500.

The light receiving element 100 includes individual electrodes (chrome patterns) 11 formed discretely in the main scanning direction and a band-shaped common electrode (IT
A photoconductive layer (a-Si) 12 is sandwiched between the individual electrodes 11, the photoconductive layer 12. The overlapping portions of the common electrodes 13 form a plurality of sensor pixels 101 having a sandwich structure and serving as photoelectric conversion elements.

The insulating member 500 includes a light transmitting portion 51 that transmits light and a light shielding portion 52 that blocks light. Translucent part 51
As shown in FIG. 2, each pixel 10 of the light receiving element 100
1 and is formed of a rectangular cylindrical body having the same cross-sectional area as this pixel 101. Insulating member 5 other than transparent part 51
00 forms a light shielding part 52. Moreover, the light shielding part 52 is
The light-transmitting portions 51 are formed so as to shield each other from each other. The light-transmitting portion 51 may be formed at least on the pixel 101, and the light-shielding portion 52 may be formed so as to include at least a surface that separates each light-transmitting portion 51 from each other. Therefore, as shown in FIG.
2 may be formed into wall-like bodies and arranged alternately, and the light-transmitting portion 51 may be configured in the form of a slit.

The insulating member 500 is formed by coating polyimide, for example, and forming the transparent portion 51 by patterning using photolithography. Due to the presence of the light shielding part 52, the reflected light 60 in FIG.
The reflected light from the surface of the original 200 on the left side of 0 is the pixel 101a.
In order to prevent the light from entering the document 200, the film thickness P of the insulating member 500 is calculated as P/W, where W is the width of the pixel 101, MS is the distance between the pixels 101, and distance d is the distance from the pixel 101 to the original 200.
>d/(W+S).

Next, the manufacturing process of this example will be explained.

A nichrome (Cr) film is deposited and patterned on a transparent insulating substrate 10 (Corning 7090), and further,
Amorphous silicon (a-Si) and indium tin oxide (ITO) are deposited and patterned to achieve a pixel density of 8 dat/fflI (pixel width t is 125 μm).
m) The light receiving element 100 is formed.

Next, polyimide is applied to a film thickness of 60 μm on the light-receiving element 100, and only the transparent portion 51 is etched by photolithography, so that the transparent portion 51 has a rectangular shape with a side W of 85 μm and a width S in the main scanning direction of 40 μm. An insulating member 500 consisting of a light shielding portion 52 is formed.

Next, a transparent adhesive is filled in the transparent part 51, and the insulating member 5 is attached.
A glass plate having a thickness of 20 μm, which will become the transparent wear-resistant layer 15, is placed and adhered on the 00.

4 and 5 show other embodiments of the present invention, in which the present invention is applied to an ultra-compact image reading device that uses an EL light emitting element as a light source and is integrated with a light receiving element and a light emitting element. It is.

This image reading device includes a light receiving element 100 formed on an insulating substrate 10 and an EL element formed on a transparent glass substrate 70.
A light-emitting element 700 is configured with a translucent insulating member 500 sandwiched therebetween.

The EL light emitting device 700 has a light emitting layer 73 made of ZnS:Mn etc. sandwiched between insulating layers 72 and 74 made of Y20, Si, N, BaTiO, etc.
It is supported by a common electrode 71 made of n, 0, Sn02, etc. and an opaque metal electrode 75 made of metal such as aluminum.

The light emitted from the light emitting layer 73 is applied to the metal electrode 75.
00 and the reflected light enters the light receiving element 100, a rectangular light entrance window 76 having an area smaller than the pixel part 101 of the light receiving element 100 is formed as an opening on each pixel part 101 of the light receiving element 100. .

This EL light emitting element 700 is produced by the following procedure. A transparent electrode 71 is formed by depositing ITO, In20,, SnO2, etc. on a glass substrate 70 by a sputtering method or the like, and Y20, S, i, N, BaTiO. The insulating layer 72 is formed by depositing ZnS:Mn, ZnS; An insulating layer 74 is formed, a metal such as aluminum is deposited on the insulating layer 72, and patterned by photolithography to form a metal electrode 75 having a light incidence window 76.

Further, the resolution (MTF) of the light receiving element 100 is determined by the distance between the light entrance window 76 of the metal electrode 75 and the document 200 (the thickness of the glass substrate 70), if the area of the light entrance window 76 of the metal electrode 75 is within a certain range. ) and the light receiving element 100 and the metal electrode 75
depends largely on the distance between the light incident windows 76 (thickness of the insulating member 500).

Therefore, the insulating member 500 is interposed as a spacer to ensure the distance between the EL light emitting element 700 and the light receiving element 100.

The insulating member 500 includes a light-transmitting portion 5l made of a transparent portion and a light-shielding portion 52. Transparent part 51 and light shielding part 5
2 has the same structure as the first embodiment. That is, if we focus on the pixel 101a and explain it, the original 20
The reflected light from 0 passes through the light incidence window 76a directly above the pixel 101a.
A light shielding portion 52 is formed to prevent light from being guided to the pixel 101a through the light entrance window 76b adjacent to the light incident window 76b. Therefore, the transparent portion 51 may be formed to include a surface that separates the transparent portion 51 from each other.

This image reading device includes a light receiving element 100 on an insulating substrate 10.
An EL light emitting element 700 is prepared on a glass substrate 70, and an insulating member 500 having a light transmitting part 51 and a light shielding part 52 is manufactured.
Finally, a light receiving element 100 and an EL light emitting element 700 are fabricated.
the insulating member 500 so that the metal electrode 75 side of the
It is formed by joining with adhesive 800 with .

Next, a specific method for creating the insulating member 500 will be described.

As a first example, transparent photosensitive glass is used as the insulating member 500.
Each pixel 101 is placed on this insulating member 500.
A rectangular mask (not shown) is placed so as to correspond to the top, and ultraviolet rays are irradiated from above, and then heat treatment is performed to crystallize only the exposed portion and make it opaque, thereby forming a transparent part 51 and a light shielding part 52. form.

As a second example, polyimide sheet is used as the insulating member 500. That is, as shown in FIGS. 7(a) to 7(f), first, a photoresist 53 is spin-coated on the first surface of a polyimide sheet 50 to be processed. Coat by roll coating or printing and bake. Next, a photoresist 5 is applied to the second surface opposite to the first surface.
Coat 4 and bake. Next, a photomask (not shown) is placed on the second surface, and ultraviolet rays are irradiated (exposed).
Develop to form desired pattern. Subsequently, the polyimide sheet 50 is etched, and after cleaning, the resist 50 is etched.
3.54 is removed to form an insulating member 500 having a light-transmitting portion 51 and a light-blocking portion 52.

Further, as shown in FIGS. 8(a) to 8(d), after applying wax 91 on a glass or ceramic substrate 90, a polyimide sheet 50 is attached, and a photoresist 5
Coat 3, bake, and apply a photomask (
(not shown) is placed, exposed to ultraviolet light, and developed to form a desired pattern. Next, polyimide sheet 50
After etching and cleaning, the resist 53 and wax 91 are removed to form an insulating member 500 having a light transmitting portion 51 and a light shielding portion 52. According to this method, the insulating member 500 can be formed on the substrate 90.
Easy to handle.

In the above embodiments, instead of polyimide sheet,
Metal foil can also be used.

Further, as shown in FIGS. 9C to 9C, a negative resist 55 is placed on the insulating substrate 10 on which the light receiving element 100 is formed.
(Manufactured by Tokyo Ohka Kogyo Co., Ltd.: Product name PMER-N-HC4
0), patterned by exposure and development to form a light-transmitting part 51 and a light-blocking part 52, and then coated with E.
The glass substrate 70 on which the L light emitting element 700 is formed may be placed with an adhesive 800 interposed therebetween. In FIG. 10(c), the same components as those in FIG. 4 are designated by the same reference numerals.

In addition, crystallized glass (for example, Photoform, etc. manufactured by Corning Inc.) in which the part corresponding to the transparent part 51 is drilled
This can also be realized by using as the insulating member 500. Also,
A transparent glass plate is used as the insulating member 500, and only predetermined areas of the transparent glass plate are dyed to form the light shielding part 52.
It is also possible to form

In the above-mentioned image reading device integrated with a light receiving element and a light emitting element, a drive signal for emitting light from the EL element is transmitted to the metal electrode 75.
and the transparent electrode 71, the portion of the light emitting layer 73 sandwiched between these two electrodes (the portion of the light emitting layer 73 excluding the portion directly above the light incidence window 76) emits light, and the light emitting layer 73 directly above the pixel 101 emits light. Light is not emitted from the light emitting layer 73 in the portion and directly irradiates the pixel 101 . The light emitted upward is reflected by the original 200, and the reflected light is applied to each pixel 101 through the light entrance window 76, and is converted into an electrical signal corresponding to the density of the original. Further, the light that enters the pixel 101a of the light receiving element 100 is only the reflected light from the document surface directly above the pixel 101a, and the light that enters the adjacent light entrance window 76b can be blocked by the light shielding part 52. It is possible to improve the resolution of Then, by extracting electrical signals in time series from the pixels 101 of the light receiving element 100, an image signal for one line of the document surface can be obtained.

FIG. 6 shows another embodiment of an image reading device integrated with a light receiving element and a light emitting element, in which the light shielding part 52 has already been formed by the method described in the first example of the specific production of the insulating member 500. On an insulating member 500 made of a glass substrate, a metal electrode 75 having a light entrance window 76, an insulating layer 74, a light emitting layer 73,
An insulating layer 72 and a transparent electrode 71 are sequentially formed, and an insulating and transparent passivation film 900 made of polyimide or the like is deposited to cover them, and this insulating member 500 is formed.
The transparent part 51 and the light receiving element 1 manufactured in the same manner as in the above example
The two are bonded via a transparent adhesive 800 so that the pixel 101 portion of pixel 00 corresponds to the pixel 101 portion of pixel 00. In the figure, the fourth
Components that are the same as those in the figures are given the same reference numerals.

According to this embodiment, the bonding process using the transparent adhesive 800 can be completed only once, and the number of manufacturing steps can be reduced.

(Effects of the Invention) According to the present invention, the insulating member interposed between the light-receiving element and the document surface is composed of a light-transmitting part and a light-blocking part, and each pixel of the light-receiving element receives light from the document surface located directly above it. Only the reflected light enters, and the light reflected from other parts of the document surface is blocked by the light shielding part, so unnecessary reflected light does not enter the pixels, improving the resolution of the light receiving element and improving the focus. The depth can be increased.

[Brief explanation of the drawing]

FIG. 1 is an explanatory longitudinal cross-sectional view of an image reading device according to an embodiment of the present invention;
2 and 3 are explanatory plan views of the insulating member of the above embodiment, FIG. 4 is an explanatory cross-sectional view of an image reading device showing another embodiment of the present invention, and FIG. FIG. 6 is a cross-sectional view of an image reading device showing another embodiment of the present invention, and FIGS. 7(a) to (f) show the manufacturing process of an insulating member in this embodiment. Explanatory drawings, Figures 8(a) to (
d) is an explanatory diagram showing the manufacturing process of the insulating member in this embodiment, FIGS. FIG. 11 is an explanatory cross-sectional view of an image reading device using a conventional fully contact type image sensor, and FIG. 11 is an explanatory cross-sectional view taken along the line XI-XI' in FIG. 200...Original 300...Reflected light 500...Insulating member 700...EL light emitting element 0...Insulating substrate 1...Transparent part 2... Light shielding part 00... Light receiving element 01... Pixel Figure (a) Figure

Claims (1)

[Scope of Claims] An image reading device that includes a light receiving element and a light source, irradiates light from the light source onto a document surface located above the light receiving element, and makes the reflected light enter the light receiving element, comprising: an insulating member is interposed between the element and the document surface,
An image reading device characterized in that a light-transmitting portion is formed in the insulating member located on each pixel of a light receiving element, and a light-blocking portion is formed in the insulating member including a surface that separates the light-transmitting portion from each other.