JPS60210867A - Linear image sensor - Google Patents

Abstract

PURPOSE:To obtain the titled device by enabling sifficient enhancement of the luminance on an original writing by a method wherein transparent windows through which illuminating light can pass are formed between a plurality of cells arranged in a dimension. CONSTITUTION:On a transparent substrate 100, a light shield layer 102 common to all the cells produced by coat of a high-insulating material such as SiO2 or Al2O3 on a low-resistant thin film of Cr or Al and a light shield layer 106 positioned below it and having hookform projections 104 at a fixed interval are formed. Next, a photoconductive layer 108 made of an amorphous hydrogenated Si film is provided on the projection 104, and a common electrode 110 is formed from on top of the layer 102 to the end of the layer 108; besides, discrete electrodes 112 are so formed as to extend from the other end of the layer 108 to the layer 106 along the projection 104. A light transmitting window 114 is provided between the electrode 110 and the layer 108, and a light transmitting window 8 between the layers 108 and 106, and the light from a light source is guided to the original writing via windows 114 and 118 from below the substrate 100.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an inear image sensor, and particularly to improvements in contact type and close contact type linear image sensors.

[Background of the invention]

A predetermined document reading device is used in facsimile machines, e-mail machines, copying machines, and the like. This document reading device is a one-dimensional linear image sensor that uses devices such as COD (charge-coupled devices), which is based on IC (integrated circuit) technology that has been developed around MOS devices in response to demands for higher speed and higher reliability. It's used a lot.

However, such a width in the longitudinal direction of the senna has the disadvantage that the optical path length from the paper to the senna increases, leading to an increase in the size of the apparatus. Further, a fine adjustment mechanism for focusing is essential, and the adjustment work is complicated, which is disadvantageous.

In order to improve these disadvantages, a contact plate sensor was devised. The contact type sensor has a sensor width that corresponds to the width of the document, and uses a 1:1 optical system such as a gradient index micro rod lens array (hereinafter simply referred to as a rod lens array) or an optical fiber array. The distance between the document and the sensor is shortened by using the sensor. Such a contact type sensor will be explained with reference to FIGS. 1 to 6.

FIG. 1 schematically shows an example of a document reading device such as a facsimile machine that uses a contact type sensor. In this figure, the document is placed between the roller hand y10°12 and the guide means 1.
4.1+5, the signal is sent from the left to the right in the figure as indicated by the dashed line L1. This document is irradiated with light as indicated by a broken line 12 from a light source 18 . This light is reflected by the surface of the document and further reflected by the mirror 20. Rod lens array 22. mirror 24
The light enters the image sensor 26 via the . This image sensor 26 is driven by a drive IC 28,
A signal corresponding to the image of the original is outputted to the outside from an output terminal 32 via an output circuit 30. As described above, this example requires an optical system consisting of mirrors 20.24 and rod lens array 22.

Next, in FIG. 2, another example of a contact type sensor is shown.9 In this figure, the image sensor 40 is placed entirely on a sandwich 7 eyeper 42. The sandwich fiber 42 is constructed in a sandwich shape by glass 44, 46 and an optical fiber array 48, and the light receiving section 50 of the image sensor 40 is connected to the lens array 4.
It is located on 8. S/German Tefiber 42 is
A part of the contact fiber 52 disposed on the contact fiber 52 has an optical path continuous with the optical fiber array 48 so that the light incident on the fiber 52 reaches the light receiving section 50. There is. Light output from an illumination light source such as a light emitting diode 58 held on a mount 56 is input to the fiber 52 after being reflected by the original 60 as shown by a solid line.

Next, FIG. 3 shows still another example of the contact type sensor. In the example shown in this figure, the rod lens array 70 is arranged differently compared to the example shown in FIG. , are made to enter the image sensor 76 only through the rod lens array 70. The image sensor 76 is a large-sized image sensor that corresponds to the width of the document 74. In this example, mirrors 20.24 are not required compared to the example shown in FIG.

In addition, in an example in which the light source 72 is moved to the back of the image sensor board 76 and a part of the image sensor board 76 is provided with an illumination window through which light can pass, the illumination light flux is more effectively directed toward the document surface.
4 and enters the rod lens array 70.

However, as described above, in the close-contact type sensor, not only must an expensive rod lens array or optical 7-eye array be used, but also some kind of focus adjustment mechanism is required, the length of the optical system must be increased to 100 mm. It is difficult to achieve the following, which hinders the miniaturization of the device.Also, the light transmission rate, defined as (illuminance on the light receiving surface)/(illuminance on the document surface) x 100%, is expressed by the formula 1 It will be reduced to purity.

Therefore, a direct reading sensor (hereinafter referred to as a "contact sensor") that directly reads the data without using a convergent optical system or optical guide system such as an optical fiber (-) has been proposed. The light from the document surface is directly received by the light-receiving surface without using a convergent optical system between the sensor and the light-receiving surface.This contact type sensor is explained with reference to FIGS. 4 to 9. explain.

FIG. 4 shows an example of a contact type sensor as a cross-sectional view, and FIG. 5 shows a part of the sensor as viewed from the arrow 2 in this figure as a plan view. The example shown in FIG. 6 is an improved version of the one shown in FIG. FIGS. 7 to 9 compare the light reflection angles on the document surface in various contact type sensors.

First, in FIGS. 4 and 5, the contact sensor 80 is placed directly under the document 82, and a dimming layer 8B is formed on the transparent substrate 84 except for the transparent window 86. A photoelectric conversion layer 90 is formed at an appropriate position on the photoelectric conversion layer 90, and individual electrodes 96 (not shown in FIG. 4) are formed on the entire transparent protective layer 92.

As shown by arrow LA in FIG. 4, light is irradiated from below the contact sensor 80, a portion of which passes through the transparent window 86, is further reflected by the original 82, and enters the photoelectric conversion layer 90. An outline of this situation is also shown in FIG.

In the example shown in FIG. 6, a light-transmitting window 98 is further provided. That is, the light-transmitting windows 8 are provided on both sides of the photoelectric conversion layer 90.
6.98 are provided respectively.

In this example, as shown in FIG.
The light passes through 6 and 98, is reflected by the original 82, and enters the photoelectric conversion layer 90.

Next, each device will be compared with reference to FIGS. 7 to 9. First, when no light-transmitting window is provided as shown in FIG. 7, the incident angle θC of the light traveling as indicated by the arrow LC is larger than the incident angle θA in the case shown in FIG. When this angle of incidence is large, light is dispersed on the photoelectric conversion layer 90, resulting in a decrease in the amount of light received. Therefore, in order to increase the amount of light received, it is better to have a smaller incident angle. To this end, the light-transmitting windows 86, 98 should be formed as close to the photoelectric conversion layer 90 as possible, and the area of the light-transmitting windows 86, 98 should be as shown in FIG. 8 as well as in FIG. 9. It is preferable to increase it to . Even in this case, the light amount transmission rate is limited to 10 inches.

In this way, for example, in the example shown in FIG. 8, that is, FIGS. 4 and 5, the amount of light reaching the document surface is insufficient, and even if a transparent electrode is used for the common electrode 94, etc. The inconvenience will not go away. Furthermore, the illuminance or amount of light on the photoelectric conversion layer 90 is likely to be affected by variations in the incident angle of the illumination light flux, 0A, and the dimensions of the light-transmitting window 86, which causes the disadvantage that variations in the sensor output become large.

In addition, in the examples shown in FIGS. 6 to 9, although the illuminance on the document surface is improved, this is still not sufficient, even if the common electrode, the electrode 942, and the individual electrode 96 were both transparent electrodes. However, the illuminance on the surface of the document is not satisfactory. Furthermore, the electrical resistance of the transparent electrode is lower than that of metals such as kl, Cr.
, Au, etc., which causes the disadvantage that the response speed decreases.

Although these drawbacks have been explained as occurring when illumination light passes through the contact sensor substrate 88, the contact type sensor in which a rod lens array is arranged instead of the transparent protective layer in FIG. 4 also has exactly the same drawbacks. As described above, the contact type sensor does not require the expensive optical system and complicated focus adjustment required by the close contact type sensor. The invention has been made in view of the above, and an object of the invention is to provide a linear image sensor that can sufficiently increase the illuminance on the surface of a document.

[Summary of the invention]

That is, the present invention attempts to achieve the above object by using an image sensor that forms a transmission window through which illumination light can pass between cells arranged in a plurality of dimensions.

〔Example〕

Since the image sensor structure according to the present invention provides the same effect whether it is used as a contact type or as a contact type, hereinafter, only the case where it is used as a contact type will be described in detail according to the embodiment shown in the accompanying drawings.

FIG. 10 shows a first embodiment of the invention. This figure corresponds to FIG. 5 or 6 described above. In this FIG. 10, on the transparent substrate 100,
First, a luminous layer 102 is formed in common to each cell at the upper part of the figure. Below this shimmering layer 102 is a shimmering layer 106 having hook-shaped protrusions 104 at regular intervals.
is formed. These light shielding layers 102, 10<S
teeth.

5ift on a low resistance thin film layer such as Cr'pk1.
A highly insulating material such as A40a or A40a is used and is formed by a vacuum evaporation method or a sputtering method.

Next, a photoconductive layer 108 is formed on the protrusion 104 of the luminescent layer 106. This photoconductive layer 108 is made of, for example, a film of amorphous silicon containing hydrogen, that is, amorphous hydrogenated silicon (hereinafter simply referred to as RA-8i:HJ), and is formed by vacuum evaporation, sputtering, or ionization.
CVD
position).

Next, a common electrode 110 is formed from above the photoconductive layer 102 to an end of the photoconductive layer 108 , and an individual electrode 112 is formed from the other end of the photoconductive layer 108 along the protrusion 104 to the photoconductive layer 108 . It is formed in such a way that it spans. These common electrodes 1101 and individual electrodes 112 are made of, for example, Al, Au, C.
It is formed using a metal material with low electrical resistance, such as R, by a method such as vacuum evaporation or sputtering. The common electrode 110 is formed in common to the plurality of photoconductive layers 108, whereas the individual electrode 112 is formed in common to the plurality of photoconductive layers 108.
08 respectively.

Further, as shown in the figure, a common electrode 110 and a photoconductive layer 10
A transparent window 114 is formed between the photoconductive layer 108 and the protrusion 104, a transparent window 116 is formed between the adjacent photoconductive layers 108, that is, between the protrusions 104, and a transparent window 116 is formed between the photoconductive layer 108 and the optical layer 106. A transparent window 118 is also formed. In this embodiment, the individual electrodes 112 are masked by the luminous layer 106. This is because when a diode is also created when forming the individual electrodes 112, the phosphorescent layer 106 is used as a mask to prevent the diode from being irradiated with light. Therefore, if this is not necessary, the blocking layer 106 may be replaced with a portion 12 that masks the photoconductive layer 108, as shown in FIG.
0 and a lower part 122 in the figure, and the luminous layer 12
0 may be formed as an isolated island.

In addition, the common electrode 1101 and the individual electrodes 112 are connected to Snug
, In, 0. A transparent electrode may also be used.

However, in this case, as described above, the response speed of each photocell decreases, so this is limited to cases where a very high speed is not required.

Next, the overall operation of the above embodiment will be explained. As explained in FIGS. 7 to 9, light emitted from a predetermined light source (not shown) is transmitted from below the transparent substrate 100 to the document surface (not shown) through the transparent windows 114, 116° 118. ). Therefore, the amount of light reaching the document surface increases, and therefore the signal S/
This results in an improvement in the N ratio.

Next, a second embodiment of the present invention will be described with reference to FIGS. 12 and 13.

FIG. 12 is a diagram corresponding to FIG. 10 or 11, and a cross section taken along the line xm-xm of FIG. 12 is shown in FIG. 13. 12 and 16, a plurality of individual electrodes 202 are formed on a transparent substrate 200 using a highly transparent material such as Or. The individual electrodes 202 are formed so that the cross-sectional area of the rear end is larger than that of the front end.

Next, a-3i:H photoconductive layers 204 are formed on the tips of the individual electrodes 202 by the method described above.

Furthermore, a common electrode 20 is superimposed on these photoconductive layers 204.
6 is formed. This common electrode 206 is formed as a transparent electrode by the method described above. Note that the photoconductive layer 20
The arrangement intervals of 4 are the same as those shown in FIG. 10, and transparent windows 208 are formed in each.

Next, the operation of the second embodiment will be explained.

First, the transparent window 208 formed between the photoconductive layers 204 is
It is sufficiently enlarged compared to what is shown in FIG. 10 or FIG. 11. Therefore, even if the light transmittance of the common electrode 206 is not necessarily high, a sufficient amount of light can be made incident on the document surface. On the other hand, since the area of the photoconductive layer 204 is expanded, the S/N ratio is improved. Furthermore, since the cross-sectional area of the individual electrodes 202 increases at the rear end portion, the resistance value decreases, thereby improving the response speed. Since this individual electrode 202 also functions as a light layer, the structure of the entire cell is simplified and there is no need to provide an insulating layer.

Next, as shown in FIG. 14, when light is irradiated from the light source 604 to the image sensor 300 having the above configuration through the light refracting plate 302 shown enlarged in FIG. The light is refracted by θφ and enters the document surface obliquely, that is, from the direction of angle θψ. According to this method, the document surface directly below each light receiving element can be illuminated, so that resolution can be improved. Note that the light refracting plate 602 can be easily produced in large quantities by etching a glass plate, using a plastic replica, or the like.

In the above embodiments, a-8t:H was used as the photoconductive layer, but the present invention is not limited to this in any way, and the present invention is not limited to this, but can also be used for thin photoelectric conversion type or photovoltaic type elements, PIN photodiodes, etc. etc. may also be used. The shapes of other electrodes and the like can also be changed within a range that provides a predetermined function.

〔Effect of the invention〕

As explained above, according to the image sensor according to the present invention, since a light transmitting window is also provided between the light receiving parts made of photoelectric material arranged in a -dimensional shape, the amount of illumination light reaching the document surface is There is an effect that the illuminance can be sufficiently increased.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway schematic front view showing a conventional example of a document reading device using a contact type sensor, FIG. 2 is a partially broken perspective view showing another conventional example of a contact type sensor, and FIG. The figure is a partially broken perspective view showing still another conventional example of a contact type sensor, Figure 4 is a sectional view showing a conventional example of a contact type sensor, and Figure 5 is a section viewed from arrow V in Figure 4. A plan view, FIG. 6 is a partial plan view showing another conventional example of a contact type sensor, FIG. 11 is a partial plan view showing a modification of the image sensor shown in FIG. 10; FIG. 12 is a partial plan view showing a second embodiment of the present invention; FIG. FIG. 13 is a cross-sectional view taken along the line ■-XI in FIG. 12, FIG. 14 is an explanatory diagram showing one means of light incidence on the image sensor, and FIG. 15 is an explanatory diagram showing an enlarged view of the light refracting plate. . 102.106,120,122... Shiyahikari layer 10
8.204 ... Photoconductive layer 110.206 ... Common electrode 112.202 ... Individual electrodes 114.116, 118, 208 ... Transmission window 302
...Light refracting plate. Agent Patent Attorney Sanro Kimura Figure 1 Figure 2 Figure 5 Figure 6 Figure 12 Figure MLB

Claims (3)

[Claims] (1) A linear image in which a plurality of light-receiving parts made of photoelectric material are arranged one-dimensionally adjacent to each other on a predetermined substrate corresponding to the document width, and this substrate becomes part of the optical path of illumination light. A linear image sensor, wherein a transmitting means through which the illumination light can pass is formed between the adjacent light receiving parts. (2) The linear image sensor according to claim 1, wherein a light refracting means is disposed between the light receiving section and the document to make illumination light from the document obliquely enter the light receiving section. (3) The linear image sensor according to claim 1 or 2, wherein the photoelectric material is made of amorphous hydrogenated silicon;