JPH0369905A - Image reading element - Google Patents

Abstract

PURPOSE:To improve resolving power and photoelectric current by facing the end face of an optical waveguide opposite to a reading object and providing two core layers having refractive index larger nearer the central part in the optical waveguide. CONSTITUTION:The end face of the optical waveguide of the image reading element in which the optical waveguide is used in the photodetecting system of images faces the reading object 2 and the optical waveguide has at least the two core layers 11a, 11b having the refractive index larger nearer the central part. Namely, more light can be taken into the entire part of the waveguide at the equal resolving power if the prospective angle to an original 2 is decreased by decreasing the ratio of the refractive index of the core layer 11b and the refractive index of the clad layer 12 near the side face at the end face of the optical waveguide and if the prospective angle to the original is widened by increasing the ratio of the refractive indices of the core layer 11a and the clad layer near the center of the waveguide. The end face type sensor which has the excellent stability of the resolving power and is further large in the quantity of the received light is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image reading element, and in detail, a factor).
The present invention relates to an end-illuminated image reading device using an optical waveguide in a light receiving system in an image reading device used in a part of an image scanner such as a digital copying machine.

[Conventional technology]

2. Description of the Related Art An end-illuminated image reading device using an optical waveguide (light guide path) in a light receiving system of an image reading device is known. Image reading elements that use such a light guide path as a light receiving system have a light irradiation system for the original, compared to those that use a reduction optical system or a same-magnification imaging system, which are conventionally used in facsimile machines. It has the advantage of being able to optically separate the light-receiving system for the photoelectric conversion unit and the photoelectric conversion unit, and development is progressing with the aim of applying it to applications that require high resolution such as detailed figures, drawings, and photographs. .

By the way, in an end-face type sensor (edge-illuminated image reading element), the light incident from the end face of the optical waveguide reaches the photoelectric conversion part, but the incident angle of the light at the end face of the optical waveguide at that time is different from the core layer of the optical waveguide. It is uniquely determined by the ratio of the refractive index to that of the cladding layer. That is, when the ratio of the refractive index between the core layer and the cladding layer of the optical waveguide is small, the incident angle of light confined within the optical waveguide and transmitted to the photoelectric conversion section becomes small; When the ratio of the refractive index between the layer and the cladding layer is large, the incident angle of light transmitted to the photoelectric conversion section becomes large. Therefore, in the edge type sensor,
It cannot be unconditionally determined whether the ratio of refractive index between the core layer and the cladding layer is larger or smaller.This can be explained as follows using Figs. 18 and 19. It will be done.

FIG. 18 is an example of a case where the ratio of the refractive index of the core layer 11 <ncore) to the refractive index (nclad) of the cladding layer 12 is small, and in this case, the incident angle of light (represented by a broken line) is small. , in the distance between the document 2 and the sensor (more precisely, the optical waveguide end surface), there is no overlap in the area of the document surface captured (read) by the adjacent leading waveguide end surface, and the resolution of the sensor is high. There is little variation in sensor resolution with respect to distance variations. But on the other hand,
Because the angle of incidence of light is small.

The end face of the optical waveguide takes in the absolute amount of light from the two sides of the original, so it is not possible to obtain a large photocurrent, and the S/N of the sensor is low.
This results in a deterioration of the ratio.

On the other hand, FIG. 19 shows an example in which the ratio (ncore/nclad) of the refractive index between the core Jll and the cladding layer 12 is large. In this case, since the angle of incidence of light is large, the absolute amount of light taken in from the two sides of the document becomes large, but at the same time, the areas of the document surface taken in by the end surfaces of adjacent optical waveguides overlap in the distance between the document and the sensor. The problem is that the resolution of the sensor deteriorates as the distance between the document and the sensor increases, and that the resolution also increases as the distance between the document and the sensor changes.

In other words, with conventional (conventional) image reading elements,
The resolution of the sensor and the stability of the resolution with respect to variations in the distance between the sensor documents and the amount of light received by the sensor are in a contradictory relationship, and the reality is that it is impossible to satisfy both at the same time.

[Problem to be solved by the invention]

It is an object of the present invention to avoid the above-mentioned disadvantages, to have excellent resolution and excellent resolution stability even when the distance between the document and the sensor changes, and to have an edge surface that receives a large amount of light compared to the conventional method. type sensor.

[Means to solve the problem]

The first aspect of the present invention is that in an image reading element in which an optical waveguide is used in the light receiving system for one image, the end face of the optical waveguide faces the object to be read, and the leading waveguide has a refractive index closer to the center. It is characterized by having at least two core layers with a large .

The second aspect of the present invention is that in an image reading element in which an optical waveguide is used in the image receiving system, the end face of the optical waveguide faces the object to be read, and the end face becomes larger as it moves away from the center. has an inclination angle, or
The end face is characterized by having an inclination angle with respect to the object to be read at a position away from the center.

A third aspect of the present invention is an image reading element in which an optical waveguide is used in the image receiving system, in which the end face of the optical waveguide faces the object to be read.

The end face of the leading waveguide is bowl-shaped and has a lens function.

Incidentally, the inventors of the present invention have conducted studies from various angles in order to achieve the above-mentioned problem, and in any case, the most important question is how to selectively read only the document area that the sensor actually requests as image information. It has been confirmed that image reading can be solved by devising the end face of the optical waveguide, and furthermore, the vicinity of the end face.The present invention has been made based on this finding.

The present invention will be described in more detail below with reference to the accompanying drawings, but prior to that, let us once again understand the positional relationship between the original and the end face of the optical waveguide.

Now, consider a case where the end face of the optical waveguide of the sensor faces the original at a certain distance. What one sensor actually needs as image information (the area where you want to capture light) is the first
In the figure, N indicates an area in which light is not desired to be taken in, and this is where the resolution of the sensor is degraded. Note that this area N is originally an area for another adjacent sensor.

Therefore, in FIG. 1, the maximum angle of view that does not degrade the resolution of the sensor is the angle shown by the solid line near the side of the optical waveguide M (core layer 11), and the angle shown by the broken line at the center of the optical waveguide. It's an angle. Near the side surface of the optical waveguide end face, the angle of view with respect to the original 2 is reduced by reducing the ratio of the refractive index of the core layer to the refractive index of the cladding layer, and near the center of the optical waveguide, the angle of view between the core layer and the cladding layer is reduced. By increasing the ratio of refractive indexes, the angle of view relative to the original can be widened, covering the entire light guide path.
Compared to a structure in which the ratio of the refractive index between the core layer and the cladding layer is reduced, more light can be taken in with the same resolution.

Based on this recognition, the present invention provides the first image reading element of the three aspects that are common in the main parts.

FIG. 2 schematically shows an example of the tip (end face) of the optical waveguide according to the first invention, and the core layer of the optical waveguide has two core layers: a first core layer 11a and a second core layer 12b. layer, and the refractive index (n) of the first core layer 11a is set to the second core layer 11.
Example where the refractive index of b is larger than (n2) (nt>n2)
If the refractive index of the cladding layer 12 is 00, then ni > n, > n. Figure 3 shows the end face of the light guide shown in Figure 2 viewed from the front. can be.

3 in the figure indicates a substrate. In addition, in Fig. 2, the core layer is made of two layers, the first and second layers, but the core layer is divided into three layers, the first, second, and third, and the first core layer is placed in the center of the optical waveguide, and the core layer is placed in the center of the optical waveguide. When two core layers are provided around the first core layer and a third core layer is provided around the second core layer, and the refractive indices of the first, second, and third core layers are n, n2, and n, respectively. , nU>fi, and>n□, the same effect as in FIG. 2 can be obtained. A similar effect can also be obtained by increasing the number of core layers and decreasing their refractive index continuously from the center toward the cladding layer.

In addition, the first core layer 11a and the second core layer 1 in FIG.
The refractive index ratio (n, >n□) with 2b is preferably 1<
n, /n, (1,5, more preferably !<nt/ns
<1.2.

In the case of n1/n, ≦1, the angle of view of the first core layer 11a is smaller than the angle of view of the second core layer 11b, so the effect of having two core layers is poor, and the photocurrent increases. If n1/n≧1.5, and if the refractive index of the cladding layer 12 is no, then ni >n.

Therefore, at least n, /n is >1.5, and on the other hand, the critical angle θ of light incident on the first core layer 3.1a is 0 =
5in-' 1 , but the refractive index (no) of the cladding layer is usually 1
Since 1- exceeds 1, the critical angle θ no longer exists, and therefore, for n, /n, ≦1°5,
In this case, the critical angle is constant at 90°, and even if the value of nl is increased, only the surface reflection in the core layer increases, which is contrary to the intended effect of the present invention and decreases.

As shown in FIGS. 2 and 3, there are several ways to give the core layer a refractive index distribution. For example, as shown in FIG.
After sequentially laminating the second core layer 11b and the first core layer 11a thereon, (b) the second core layer 11 is etched.
Remove up to position b. (c) Form the second core layer 11b again. (d) Next, the cladding layer is removed by etching again, and (e) the cladding layer 12 is finally deposited again. In addition, in the example shown in FIG. 5, (a) the substrate 3
On top, a cladding layer (for example soda glass) 12, a second core layer (for example +ion glass) 11b, a first core layer (
For example, TQ + ion glass) lla are sequentially laminated and (b) formed into a rectangular shape by etching. (c) Next, the refractive index around the first core layer 11a is lowered by an ion exchange method to make it equal to the refractive index of the second core layer 11b. (
d) Finally, the refractive index of the surrounding surface is further lowered to be equal to the refractive index of the cladding layer 12. Figure 6 is the 4th
By a method combining the methods shown in FIG. 5 and FIG. 5, (a) the cladding layer 12 and the second core layer 11b are formed on the substrate 3; (c) forming a second core layer (llb); (d) etching; and (e) forming a cladding layer 12.

Other methods for changing the refractive index of a part of the optical waveguide include metal diffusion, laser annealing, and the like.

Next, another optical waveguide configuration will be described that increases the amount of light received without deteriorating the sensor's excellent resolution and resolution stability without using two or more core layers.

The embodiment herein schematically shows an example of the optical waveguide according to the second invention.

As shown in FIG. 7, α is the taper angle in FIG. 0, which considers the case where a part of the end face of the light guide or the side surface of the light guide is tapered with respect to the original 2. At this time, manuscript 2
At the end surface parallel to the document 2, the viewing angle with respect to the document 2 is symmetrical as shown by the broken line. However, for an end surface that is inclined with respect to the document 2, the angle of view shown by the solid line in the figure is shown, and the angle of view to the right side of the end surface is shallower than the broken line, and the angle of view to the left side is deeper than the broken line. By utilizing this fact, as shown in FIG. 8, by tapering both end surfaces near the side surfaces of the light guide, it is possible to exclude light from areas other than the area where the sensor faces the document. Note that the same effect can be obtained even if the taper on the side surface of the optical waveguide is formed in two or more stages as shown in Figure 9, and the slope can be continuously changed as shown in Figure 10. The same effect can be obtained by doing so.

FIG. 11 is a front view of the end face of the optical waveguide shown in FIG. 8.

If the angle of the taper on the side surface of the light guide is α, then O.

(α(8v, preferably Q@<α<60°. α≦
In the case of 0°, the taper on the side surface of the light guide means that light from the outer area of the facing document 2 is taken in, so the resolution deteriorates and the intended effect of the present invention cannot be obtained. , and if the taper angle is α≧80@,
The field of view toward the center of the light guide path is limited by the presence of the tapered portion, and the amount of light received at the tapered portion is reduced, so that the intended effect of the present invention cannot be expected either.

FIG. 12 shows a perspective view of the tip of an optical waveguide that combines the means described so far, and the improvement of the characteristics in the direction perpendicular to the three surfaces of the substrate is achieved by changing the refractive index of the core layer and By making the refractive index (n, ) of the core layer 11a larger than the refractive index (layer 8) of the second core layer 11b, the characteristics in the direction parallel to the cross section of the substrate 3 can be improved. This can be achieved by creating a taper in the vicinity.

Next, a description will be given of yet another optical waveguide configuration that increases the amount of light received without deteriorating the sensor's excellent resolution and resolution stability without using the two or more core layers mentioned above. The embodiment herein schematically shows an example of the guiding waveguide according to the third invention.

In FIG. 13, the end surface of the light guide is made convex (bowl-shaped) so that the light from the position of the document 2 is focused on the focal plane.

At this time, the distance between the document and the sensor and the focal length of the optical waveguide are set so that the area (L) of the document from which light is to be captured is imaged on the focal plane to have the same size as the cross section of the optical waveguide. With this setting, the light from the area where you want to take in the light will not be reflected at the side of the light guide path while it reaches the focal plane F, as shown by the solid line in the figure. The light from the area takes the optical path shown by the broken line to form an image at the focal plane F, but since the imaging position is outside the light guide core layer, the light travels along the side of the light guide before reaching the focal plane. Therefore, a layer 4 that absorbs light is provided on the side surface of the light guide core layer on the side of the document 2 from the focal plane F, and a cladding layer 12 is provided on the side surface of the core layer on the side of the photoelectric conversion section from the focal plane. It is desirable to improve the resolution of the sensor by providing a black dye, a polymer film, a metal film, etc. as the light absorption layer 4.

Preferably, 0°3≦na, where the length of the light absorption layer is a, the distance between the original and the end surface of the light guide is n, and the refractive index of the core layer is n.
/b≦2. This preferable range of na/b is based on the following reasons. That is, if the area of the document surface that the sensor expects is S and the cross-sectional area of the core layer is 82, then S, / S,
= n"a"/b". Therefore, in the case of na/b<0.3, the cross-sectional area of the core needs to be 1710 or less of the area of the facing original, and a sufficient photocurrent can be obtained. When na/b > 2, the area of the document that captures light is 1/1 compared to the cross-sectional area of the core.
4 or less, and a sufficient photocurrent cannot be obtained.

FIG. 14 shows an example in which a light scattering region 5 is provided instead of the light absorption layer. The light scattering region 5 can be formed by forming fine irregularities on the surface of the core layer.

FIGS. 15 and 16 show the light absorption layer 4. 12 is a diagram showing that the light scattering region 5 may also be formed in the optical waveguides shown in FIGS. 2, 9, 10, and 12. FIG.

Examples of the optical waveguide material in the image reading element of the present invention include silica glass, boric acid glass, chalcogenide glass, lithium oxide, and various polymers of ZnO1. In addition, examples of the thin film forming method for forming the light guide include sputtering method, plasma CVD method, MOCVD method, sol-gel method, EB evaporation method, etc. Furthermore, ion exchange method, metal diffusion method, etc. are also used.

When creating a quartz-based waveguide using the plasma CVD method, methods for forming plasma include ECR plasma method, RF plasma method, thermionic plasma method, cold cathode plasma method, and the like. In the plasma CVD method, raw material gases for creating a quartz-based light guide include silane, disilane, oxygen, nitrogen, carbon dioxide, methane, and N20.
, tetraethoxysilane, tetraethoxysilane, ozone, etc.

Examples of the substrate material for producing the sensor of the present invention include borosilicate glass, quartz glass, pyrex glass, alumina, aluminide, boron nitride, and the like.

The light source for document illumination used in the present invention includes a fluorescent lamp,
Examples include tungsten lamps, halogen lamps, LEDs, laser diodes, EL lamps, etc. In addition, for the purpose of concentrating the light from the light sources, these light sources are combined with cylindrical lenses, microlens arrays, fluorescent films, and optical fiber arrays. In some cases, combinations with thin glass, polymer films, etc. are used.

In the edge-type sensor according to the present invention, when the film thickness of the light guide is shorter than the width of the cross section of the light guide, the resolution characteristic of the sensor is mainly in the sensor main scanning direction (the main axis of the light guide and the direction of the substrate surface). In many cases, the resolution is determined by the resolution (direction perpendicular to the linear direction), and in that case, the shapes shown in Figures 2, 8.13, 14.15, and 16 should be formed only on the side surface of the light guide. The same effect can be obtained by

In addition, instead of forming the optical waveguide using a thin film process,
The present invention can also be realized when formed using glass optical fiber, plastic fiber, thin glass, or the like.

Furthermore, the method described in the present invention can also be applied to image guides using optical fibers such as endoscopes to improve resolution.

〔Example〕

Next, examples and comparative examples will be shown.

Examples 1 to 6 and Comparative Examples Pyrex glass (approximately 1 piece thick) was used as a substrate for forming the end-face type sensor.

First, a Cr light-shielding layer was formed on the substrate by sputtering in order to prevent stray light from entering the photoelectric conversion section from the substrate side. The substrate temperature was 80°C, the Ar gas partial pressure was 5+aTorr,
Oxygen gas partial pressure is 2+mToor, RF power is 2v/a
It was set as d. The film thickness is approximately 1000 people.

Furthermore, a chromium oxide film was formed on the Cr surface by the same sputtering method. Substrate temperature is 80°C, Ar gas partial pressure is 5 mToor, oxygen gas partial pressure is 2 mToor, RF
The power was 2W/cd. The film thickness is approximately 300 people.

The purpose of forming a chromium oxide film on this Cr film is to reduce the reflectance of the light-shielding layer for the radiation mode emitted from the light guide path through the cladding layer. This is to prevent stray light.

Next, a 5iON film for a light guide was formed by RF plasma CVD. First, silane, nitrogen, and carbon dioxide gas were used as 0M material gases to form a cladding layer approximately 5μ thick.

The respective gas flow ratios were 1:20:40. The substrate temperature was 200° C., the RF power was 100 mW/aJ, and the gas pressure was ITorr. The refractive index (n) of the film was 1.46.

Subsequently, a second core layer was formed with a raw material gas composition ratio of 1:40:40. Substrate temperature is 200℃, RF power is 1
00+wW/af, and the gas pressure was ITorr. The refractive index (n) of the film was 1.47. The film thickness is 5 μm.

Furthermore, by changing the composition ratio of the raw material gas while keeping the film formation conditions the same,
Six types of first core layers were formed. The film thickness was kept constant at about 10 μm. If the composition ratio of the raw material gas is l:X:40,
Samples with x=45.50.70.80, 110, and 120 were created. The refractive index (n,) of each is 1.47
5.1.50.1.76.1.8.2.0.2.2.

ITO films were formed by sputtering as individual electrodes of photoelectric conversion elements. The substrate temperature was 150° C., the Ar gas partial pressure was 2 mToor, the oxygen gas partial pressure was 3 mToor, and the RF power was 111/d. The film thickness is approximately 1800 people.
After patterning the fabricated 0 film into the shape of individual electrodes, 5iONlpJ was formed to a thickness of about 5000λ as an insulating film between the eyebrows. The film formation conditions are exactly the same as those for the cladding layer.

Next, a contact hole with IτO is formed in a part of the glabella insulating film, and a
-3i photoelectric conversion section was formed. The conditions here are: substrate temperature 250℃, pressure ITorr, RF power 100++
+W/j, and silane and hydrogen were used as source gases. The composition ratio of silane:hydrogen was 1:4. Film thickness is approximately 1μ
It is m.

After patterning the a-3i layer, a contact hole with the a-5J9 was formed in a part of the interlayer insulating film again under the same conditions as before. Substrate temperature is 80℃, Ar gas pressure is 5mTo
rr, RF power was 2ra'4/aj. The film thickness is approximately 2000 mm to ensure reliability of the primary wiring.

An AM film with a theoretical thickness of approximately 1μ was formed on the Cr film by vacuum heating evaporation (substrate temperature 120°C).
As shown in FIG. 17, the M common electrode is formed to cover the entire surface of the a-3i photoelectric conversion section, thereby also serving to prevent stray light from coming from above the sensor.

The first core layer was etched to the interface with the second 37 layer using the ECR etching method. Etching gas: CHF3, μ wave power 500v, grid acceleration voltage 5
After setting the temperature to 00V, a second core layer was formed again according to the procedure shown in FIG. 4, and after etching was performed again to the cladding layer interface, a cladding layer was formed.

The thickness of the second core layer and the cladding layer are both 5μ, and the shapes of the first core layer and the second core layer are etched so that they are 10μ- and 20μ-, respectively, when viewed from the end surface of the light guide. I did it. Each light guide path was formed to have a depth pitch of approximately 30 μm.

Finally, after cutting the end face of the light guide using a dicing saw,
The end face was polished using a cerium pad so that the end face of the light guide became a mirror surface, and the sensor shown in FIG. 17 was manufactured.

For comparison, an image reading element was produced in the same manner as in Example 1 except that only the second core layer was formed.

However, the refractive index (n3) of the core layer here is 1.47. The area of the core layer is 20 μmO (Comparative Example 1).

The evaluation of these seven types is as shown in Table-1.

As can be seen from Table ■, good resolution and large photocurrent can be achieved by using the first and second core layers and making the refractive index of the first core layer larger than the refractive index of the second core layer. can get.

Table-1 (Note) The evaluation in Table 1 was performed as follows.

A black and white stripe pattern with approximately 30 μm line and space was used as a manuscript for evaluating the resolution of the sensor. Light is irradiated onto the original using a cylindrical lens (CL-1 manufactured by Sigma Koki Co., Ltd.) using a cylindrical lens (CL-1 manufactured by Sigma Koki Co., Ltd.).
070-15PM).

The distance between the document and the sensor was set to approximately 30 μm, and the zero resolution was set so that the centers of the white stripe pattern and black stripe pattern of the document coincided with the center of the end surface of the end sensor light guide path.
The sensor document was positioned, and the photocurrent flowing through the sensor facing the white stripe was Iv, the photocurrent flowing through the sensor facing the black stripe was IB, and the resolution R was defined as Iw+IB. A value of H close to 1 means that the partial resolution is high, and a larger Iw means a larger amount of light received.

The evaluation standard is R≧0.85. If Iw≧0.5nA is satisfied...OR≧0.80. When Iw≧0.5nA is satisfied・When none of the conditions above 0 are satisfied...Δ
And so.

Examples 7 to 12 and Comparative Example 2 In Example 1, a single core layer was formed by plasma CVD without dividing the core layer into first and second core layers.

The gas flow ratio of silane, nitrogen, and oxygen was 1:50:40, and the other film forming conditions were the same as in Example 1.

The refractive index (n) of the core layer was 1.50.

Further, a part of the taper shown in FIG. 11 was formed by etching in a portion of the core layer close to the cladding layer side. The etching conditions are also the same as in Example 1.

Taper angles are 5@, 20', 60°, 65°, 75
There were six samples: @, 85@. The non-tapered core layer portion had a volume of 10 μl110 when viewed from the end face of the leading waveguide.

The manufacturing method other than the light guide path portion is completely the same as in Example 1. For comparison, a case without a taper angle (Comparative Example 2) was also evaluated. The results are shown in Table-2.

Table-2 (Comparative Example 3) was also evaluated.

Table 3 Examples 13 to 19 and Comparative Example 3 In Example 1, a lens was formed by shaping the core layer without dividing it into a first and second layer, and adding curvature to the end face of the core layer. The refractive index (n) of the core layer was 1.50. The core layer shape, focal point distance f, etc. are as shown in Table 3.

Further, a light absorption layer as shown in FIG. 13 was formed by the length of the side surface a of the core layer. The light absorption layer was made of graphite carbon and was created by sputtering. The film thickness was approximately 1 μm under the conditions of Ar gas pressure of 5 mm Torr, RF power of 1 w/aJ, and substrate temperature of 250° C.

For comparison, the case where no curvature is provided on the end face of the light guide [Effects of the invention] As is clear from the description of the embodiments, the present invention achieves excellent resolution and improved photocurrent, and allows for detailed drawings and figures. It is effective for image input devices such as digital copying machines and facsimile machines that require high resolution such as photos and digital copying machines.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which the end face of the optical waveguide of the sensor faces a document at a certain distance. FIG. 2 is a schematic diagram of an example of an optical waveguide according to the present invention, and FIG. 3 is a front view of the end face of this optical waveguide. 4, 5 and 6 illustrate two sides of the method of manufacturing the light guide shown in FIG. FIG. 7 is an explanatory diagram of a case where the light guide path and its side surface are tapered relative to the original. FIG. 8, FIG. 9, and FIG. 10 are diagrams in which the optical waveguide and its side surfaces are continuously tapered or inclined. FIG. 11 is a front view of the end face of the light guide shown in FIG. 9. FIG. 12 is a perspective view of a device having two or more core layers and provided with a taper. FIG. 13 is a diagram showing an optical waveguide in which the end face of the core layer is formed into a convex shape (bowl shape). FIGS. 14, 15, and 16 are diagrams in which a light absorption layer or a light scattering region is formed on the outer surface of the core layer. FIG. 17 is a schematic diagram of the sensor of the present invention. FIGS. 18 and 19 are diagrams for examining the resolution of the sensor in terms of the ratio of the refractive index between the core layer and the cladding layer and the relationship between the document and the sensor. 2... Original document 3... Substrate 4... Light absorption layer 5... Light scattering region 6... Photoelectric conversion section 7... Light shielding layer 8... ITO individual electrode
9... Common electrode 11a... First core layer 11b...
・Second core layer 12... cladding layer

Claims (3)

[Claims] (1) In an image reading device in which an optical waveguide is used in the image receiving system, the end face of the optical waveguide faces the object to be read, and the optical waveguide has at least two layers having a larger refractive index toward the center. An image reading element characterized by having a core layer. (2) In an image reading device in which an optical waveguide is used in the image receiving system, the end face of the optical waveguide faces the object to be read, and the end face has a larger inclination angle as it moves away from the center. An image reading element characterized in that the end face has an inclined angle with respect to the object to be read at a position away from the center of the end face. (3) In an image reading device in which an optical waveguide is used in the image receiving system, the end face of the optical waveguide faces the object to be read, and the end face of the optical waveguide is bowl-shaped and has a lens function. An image reading element characterized by: