JPH1175015A - Image sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve picture quality, to improve reading precision, to validly use a light from a light source and to save energy by linearly arranging plural point emitting elements, image-forming a reflected light from an original in a light receiving element, making a light from the point emitting elements incident vertically and introducing a light from the point emitting elements to the original by inside reflection. SOLUTION: A light with which an original 3 is irradiated is reflected according to the concentration of the picture of an original 3, transmitted through a rod lens of a rod lens eye 9, and image-formed at a sensor IC 8. The strength information of the reflected light is outputted from the sensor IC 8 through a sensor board 7. Therefore, when the original 3 is carried on a glass plate 2, the picture information of the whole original 3 is outputted. A light introducing body 21 is provided with a recessed part 21a so that a light outgoing from a light emitting diode 5 can be made incident to the light introducing body 21 vertically without being reflected. Thus, even when a light is converged by the light introducing body 21, the original 3 is uniformly illuminated, and the variation of the output from the image sensor can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image sensor used for an image input unit of a facsimile machine, for example.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a configuration diagram illustrating a main part of a conventional image sensor disclosed in Japanese Patent Application Laid-Open Publication No. HEI 10-115,000. In the figure, a glass plate 2 is fixed to a frame 1 for positioning each component. The glass plate 2 is located on the running surface of the document 3. Also,
An LED substrate 4 is positioned and fixed to the frame 1 obliquely with respect to the glass plate 2. A plurality of light emitting diodes 5 as point light emitting elements are arranged in a straight line on the LED substrate 4, and constitute a line light source as a whole.

A light guide 6 in the form of a rectangular plate is fixed between the light emitting diode 5 and the glass plate 2 to condense the radiated light emitted from the light emitting diode 5 and guide it to the glass plate 2. Further, a plurality of sensor ICs 8 are arranged linearly on the sensor substrate 7 fixedly positioned on the frame 1 in accordance with the reading width of the image sensor. Each image sensor 8 has a length of several mm. Between the glass plate 2 and the sensor IC 8, there is provided a rod lens array 9 for erect equal-magnification imaging. This rod lens array 9 has a plurality of rod lenses (not shown) and is positioned and fixed to the frame 1.

Next, the operation will be described. Light from the light emitting diode 5 is applied to the document 3 through the light guide 6 and the glass plate 2. At this time, the light emitting diode 5
11 and 12, the light is totally reflected in the light guide 6, so that the light is prevented from diffusing, and the illuminance of the light applied to the document 3 is increased. Can be

The light applied to the document 3 is reflected in accordance with the density of the image on the document 3, passes through the rod lenses of the rod lens array 9, and forms an image on the sensor IC 8.
In the sensor IC 8, charges are accumulated according to the intensity of the reflected light, and information on the intensity of the reflected light is output via the sensor substrate 7. Therefore, when the original 3 is sent on the glass plate 2, the image information of the entire original 3 is output.

Next, FIG. 13 shows, for example, Japanese Patent Laid-Open No. 7-1625.
It is a block diagram which shows the principal part of the conventional image sensor shown by 86 gazettes. In the figure, a glass plate 2, a substrate 12, a reflection mirror 13, and a rod lens array 9 are positioned and fixed to a frame 11. A plurality of light emitting diodes 5 and a plurality of sensor ICs 8 are arranged on the substrate 12 in a straight line.

In the image sensor of this example, the light emitting diode 5 is mounted on the same substrate 12 as the sensor IC 8, and the light from the light emitting diode 5 is reflected by the reflection mirror 13 and illuminates the original 3.

Next, FIG. 14 shows, for example, Japanese Patent Application Laid-Open No. 8-1633.
FIG. 2 is a configuration diagram illustrating a main part of a conventional image sensor disclosed in Japanese Patent Application Publication No. 20-No. In the figure, a glass plate 2, a light guide 15 on which a plurality of light emitting diodes 5 are mounted, a rod lens array 9, and a sensor substrate 16 on which a sensor IC 8 is mounted are fixedly positioned on a frame 14. The light guide 15 is covered with a cover 17 except for the light exit surface 15a. Further, a light diffusion layer (not shown) that reflects light in the light guide 15 toward the emission surface 15a is provided on a part of the outer peripheral surface of the light guide 15.

In such an image sensor, the light that has entered the light guide 15 from the light emitting diode 5 is reflected by the light diffusion layer and the cover 17 and is eventually emitted from the emission surface 15a. The light emitted from the light guide 15 is applied to the original 3 through the glass plate 2. Also, manuscript 3
The light reflected by passes through the rod lenses of the rod lens array 9 and forms an image on the sensor IC 8.

[0010]

Among the conventional image sensors configured as described above, in the image sensor shown in FIG. 10, light emitted radially from the light emitting diode 5 as shown in FIG. Is refracted inward when the light enters the light guide 6, the area immediately above each light emitting diode 5 becomes particularly bright, a uniform line light source cannot be obtained, and the light applied to the document 3 is It becomes uniform and the image quality deteriorates.

Also, in the image sensor shown in FIG.
Therefore, the light cannot be condensed and applied to the document 3, and the output from the sensor substrate 12 becomes small, and the image quality deteriorates.

Further, in the image sensor shown in FIGS. 10 and 13, since there is a space between the glass plate 2 and the rod lens array 9, foreign matter may enter the optical path in this space. As described above, when a foreign substance enters the optical path, an error occurs in the density information of the image, and the reading accuracy is reduced and the image quality is reduced.

Further, in the image sensors shown in FIGS. 10 and 14, the light emitted from the light guides 6, 15 spreads the light exit surfaces of the light guides 6, 15 at an angle of 180 °. Therefore, there is a light component traveling toward the frames 1 and 14 in parallel with the glass plate 2 in addition to the light component traveling toward the document 3, and the use efficiency of the light emitted from the light emitting diode 5 is reduced. Here, in the image sensor, since the power consumed by the light emitting diode 5 is larger than that of the sensor IC 8, a decrease in the light use efficiency leads to a waste of power.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and can improve the image quality, can prevent the reading accuracy from being lowered, and can further improve the image quality. It is an object of the present invention to obtain an image sensor that can effectively use light and save energy.

[0015]

According to a first aspect of the present invention, there is provided an image sensor which is arranged linearly, receives a plurality of point light emitting elements for emitting light for irradiating an original, and receives reflected light from the original. A light receiving element, a lens body for forming an image of reflected light from the original on the light receiving element, and a plurality of concave portions having a curved surface such that light from the point light emitting element is vertically incident and covering each point light emitting element are provided. And a light guide for guiding light from the point light emitting element to the document by internal reflection.

An image sensor according to a second aspect of the present invention comprises:
A substrate, a line light source provided on the substrate and emitting light for irradiating the document, a light receiving element provided on the substrate at a distance from the line light source and receiving reflected light from the document, and a document A lens body that forms an image of the reflected light from the light source on the light receiving element, and at least one of the outer peripheral surfaces is formed of a curved surface, and guides light from the line light source to a portion of the document facing the lens body by internal reflection. And a light body.

An image sensor according to a third aspect of the present invention comprises:
A light guide having a first surface that is a plane parallel to light traveling straight from a line light source to a portion facing a lens body of a document and a second surface that is a curved surface facing the first surface is used. is there.

An image sensor according to a fourth aspect of the present invention comprises:
A line light source for emitting light for irradiating the original, a light receiving element for receiving reflected light from the original, a lens body for imaging the reflected light from the original on the light receiving element, and a space between the lens body and the original And a light guide for guiding the light from the line light source to the document by internal reflection.

An image sensor according to a fifth aspect of the present invention comprises:
An inclined surface for reflecting a component of light traveling in the light guide parallel to the document toward the document is formed at an output end.

An image sensor according to a sixth aspect of the present invention comprises:
The light guide is formed of a resin molded product.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 FIG. FIG. 1 is a configuration diagram showing a main part of an image sensor according to Embodiment 1 of the present invention, and FIG. 2 is a front view showing a light guide of FIG. In the figure, a glass plate 2 is fixed to a frame 1 for positioning each component. The glass plate 2 is located on the running surface of the document 3. An LED substrate 4 is positioned and fixed to the frame 1 obliquely with respect to the glass plate 2. LED
A plurality of light emitting diodes 5 as point light emitting elements are arranged on a substrate 4 in a straight line, and constitute a line light source as a whole.

Between the light emitting diode 5 and the glass plate 2, a rectangular plate-like light guide 21 for condensing the radiated light emitted from the light emitting diode 5 and guiding it to the glass plate 2 is fixed. As the light guide 21, for example, a molded product of a transparent resin such as acrylic is used. The light guide 21 is provided with a plurality of recesses (grooves) 21 a having a semicircular cross section that cover the respective light emitting diodes 5, so that light emitted from the light emitting diodes 5 is not refracted by the light guide 21. It is designed to be incident vertically.

Further, a plurality of sensor ICs 8 as light receiving elements are arranged in a straight line on the sensor substrate 7 positioned and fixed to the frame 1 in accordance with the reading width of the image sensor. Each image sensor 8 has a length of several mm. A rod lens array 9 is provided between the glass plate 2 and the sensor IC 8 as a lens body for erect equal-magnification imaging. This rod lens array 9 has a plurality of rod lenses (not shown) and is positioned and fixed to the frame 1.

Next, the operation will be described. Light from the light emitting diode 5 is applied to the document 3 through the light guide 21 and the glass plate 2. At this time, since the light from the light emitting diode 5 is totally reflected in the light guide 21 and travels,
The diffusion of light is prevented, and the illuminance of light applied to the document 3 is increased.

The light applied to the original 3 is reflected in accordance with the density of the image on the original 3, passes through the rod lenses of the rod lens array 9, and forms an image on the sensor IC 8.
In the sensor IC 8, charges are accumulated according to the intensity of the reflected light, and information on the intensity of the reflected light is output via the sensor substrate 7. Therefore, when the original 3 is sent on the glass plate 2, the image information of the entire original 3 is output.

In such an image sensor, the light guide 2
1, the light emitted from the light emitting diode 5 is vertically incident on the light guide 21 without being refracted. Therefore, the light emitting diode 5 is formed by the light guide 21.
Even if light from the light source is condensed, the document 3 is evenly illuminated as in the case where the light guide 21 is not provided, the variation in the output from the image sensor is reduced, and the image quality can be improved. Further, the light from the light emitting diode 5 is refracted in the thickness direction of the light guide 21 when entering the concave portion 21a, but this refraction does not adversely affect a line light source. Therefore, the refraction of the light guide 21 in the thickness direction is ignored.

In the above example, the concave portion 21a is formed in a groove shape extending linearly in the thickness direction of the light guide 21, but the concave portion may be formed as a hemispherical concave portion, for example.

Embodiment 2 Next, FIG. 3 is a configuration diagram showing a main part of an image sensor according to Embodiment 2 of the present invention. In the figure, a glass plate 2, a substrate 12, a light guide 22, and a rod lens array 9 are positioned and fixed to a frame 11. On the substrate 12, a plurality of light-emitting diodes 5 and a plurality of sensor ICs 8 constituting a line light source are arranged linearly at an interval from each other. The light guide 22 is for condensing light from the light emitting diode 5 and guiding the light to the document 3, and the first surface 22a and the second surface 22b of the outer peripheral surface are curved with an appropriate curvature. .

In such an image sensor, by using the curved light guide 22, the direction of the light from the light emitting diode 5 can be changed while being collected.
Therefore, the light emitting diode 5 and the sensor IC 8 can be mounted on the same substrate 12, and the sensor substrate 12
The S / N ratio can be improved by increasing the output from, so that the image quality can be improved. Also,
By mounting the light emitting diode 5 and the sensor IC 8 on the same substrate 12, the number of components is reduced and assembly is facilitated.

In the above example, the light emitting diodes 5 as point light emitting elements are arranged in a straight line. However, a linear light emitting member may be used as it is as a line light source. In addition, the curved surface of the light guide 22 may be formed in a polygonal shape by combining a plurality of planes forming an obtuse angle with each other. I do.

Embodiment 3 Next, FIG. 4 is a configuration diagram showing a main part of an image sensor according to Embodiment 3 of the present invention. In the figure, an emission side end 23 a of a light guide 23 which collects light from the light emitting diode 5 and guides the light to the document 3 is extended and interposed between the glass plate 2 and the rod lens array 9. The light guide 23 has a first planar surface 23 b inclined with respect to the glass plate 2 and the first surface 23 b.
The second surface 23 facing the surface 23b and curving at the incident end.
c.

In such an image sensor, since the exit side end 23a of the light guide 23 is interposed in the space between the glass plate 2 and the rod lens array 9, entry of foreign matter into this space is prevented. Is done. Therefore, there is no error in the density information of the image, the reading accuracy can be improved, and the image quality can be improved.

The component of the light emitted from the light emitting diode 5 which goes straight to the irradiation part of the original 3 is the first surface 23.
b, the component emitted straight from the light-emitting diode 5 toward the original 3 or toward the side opposite to the illuminated portion is the curved second component.
Since the light is reflected by the surface 23c and travels inside the light guide 23, the entire light emitted from the light emitting diode 5 is reduced in reflection, and the loss due to reflection can be reduced.

Embodiment 4 In the third embodiment, the light emitting diode 5 and the sensor IC 8 are mounted on the same substrate 12.
Although the example in which the light emitting diode 5 is mounted on the LED substrate 4 is shown in FIG. 5, for example, the emission side end 24a of the light guide 24 is extended as shown in FIG. Since it can be interposed between the glass plate 2 and the rod lens array 9, no error occurs in the density information of the image, and the reading accuracy can be improved.

Embodiment 5 FIG. Next, FIG. 6 is a configuration diagram showing a main part of an image sensor according to Embodiment 5 of the present invention,
FIG. 7 is an enlarged view showing the light guide of FIG. In the figure,
The exit side end 25 a of the light guide 25 is interposed between the glass plate 2 and the rod lens array 9. Also,
An inclined surface 25 b that reflects a component of light that travels in the light guide 25 in parallel with the glass plate 2 toward the document 3 is formed at the emission end 25 a.

In such an image sensor, the light guide 2
5 travels in parallel with the glass plate 2 in FIG.
As shown by the arrow, the light from the light emitting diode 5 is efficiently used because the light is reflected toward the document 3 on the inclined surface 25b. Therefore, power consumption of the image sensor can be reduced, and energy saving can be achieved.

Embodiment 6 FIG. FIG. 8 is a configuration diagram showing a main part of an image sensor according to Embodiment 6 of the present invention.
In the figure, light from a light emitting diode 5 is condensed and the original 3
The exit side end 26a of the light guide 26 that guides the light is extended and interposed between the glass plate 2 and the rod lens array 9. The light guide 26 includes a first planar surface 26 b inclined with respect to the glass plate 2 and the first planar surface 26 b.
b and a second surface 26c that is curved at the incident side end. Further, the light guide 2 is provided at the exit side end 26a.
The light component traveling in parallel with the glass plate 2 in the
An inclined surface 26d that reflects light toward is formed.

In such an image sensor, since the emission side end 26a of the light guide 26 is interposed in the space between the glass plate 2 and the rod lens array 9, entry of foreign matter into this space is prevented. Is done. Therefore, no error occurs in the density information of the image, and the reading accuracy can be improved.

The component of the light emitted from the light emitting diode 5 which goes straight to the irradiation portion of the original 3 is the first surface 26.
b, the component emitted straight from the light-emitting diode 5 toward the original 3 or toward the side opposite to the illuminated portion is the curved second component.
Since the light is reflected by the surface 26c and travels inside the light guide 23, the entire light emitted from the light emitting diode 5 can be less reflected, and the loss due to the reflection can be reduced.

Further, the inside of the light guide 26 is covered with the glass plate 2.
Is reflected toward the document 3 by the inclined surface 26d, so that the light from the light emitting diode 5 is used efficiently. Therefore, power consumption of the image sensor can be reduced, and energy saving can be achieved.

Embodiment 7 FIG. Next, FIG. 9 is a configuration diagram showing a main part of an image sensor according to Embodiment 7 of the present invention. In the figure, a glass plate 2, a light guide 27 on which a plurality of light emitting diodes 5 are mounted, a rod lens array 9, and a sensor substrate 16 on which a sensor IC 8 is mounted are fixedly positioned on a frame 14. The light guide 27 is provided on the cover 1 except for the exit side end 27a.
7.

Further, the exit side end 27a of the light guide 27 is
It is interposed between the glass plate 2 and the rod lens array 9. Further, the light guide 2 is provided at the exit side end 27a.
7, the light component traveling in parallel with the glass plate 2
An inclined surface 27b that reflects light toward is formed. Furthermore, a light diffusion layer (not shown) is provided on a part of the outer peripheral surface of the light guide 27 to reflect the light in the light guide 27 toward the emission end 27a.

In such an image sensor, the light that has entered the light guide 15 from the light emitting diode 5 is reflected by the light diffusion layer and the cover 17, and is then emitted from the emission side end 27a. The light emitted from the light guide 27 is applied to the document 3 through the glass plate 2. The light reflected by the original 3 passes through the rod lenses of the rod lens array 9 and forms an image on the sensor IC 8.

At this time, the exit side end 27 of the light guide 27 is placed in the space between the glass plate 2 and the rod lens array 9.
The presence of “a” prevents entry of foreign matter into this space. Therefore, no error occurs in the density information of the image, and the reading accuracy can be improved. In addition, since the light component traveling in the light guide 27 in parallel with the glass plate 2 is reflected toward the document 3 on the inclined surface 27b, the light from the light emitting diode 5 is used efficiently. Therefore, power consumption of the image sensor can be reduced, and energy saving can be achieved.

In the second to seventh embodiments, the light-incident side end face of the light guide is flat, but it is needless to say that a concave portion as shown in the first embodiment may be provided. Further, in the above-described example, the positioning of the original 3 by the glass plate 2 is described, but the glass plate 2 may be omitted. Further, in the above-described example, the light guide is formed of a resin molded product, but may be formed of another material such as glass.

[0046]

As described above, in the image sensor according to the first aspect of the present invention, the concave portion covering the point light emitting element is provided in the light guide, and the light from the point light emitting element is vertically incident on the light guide. Therefore, even if light from the point light emitting element is condensed by the light guide, the document is uniformly illuminated as in the case where there is no light guide, the output variation is reduced, and the image quality is improved. Can be.

According to a second aspect of the present invention, at least one of the outer peripheral surfaces of the light guide is constituted by a curved surface, and the light from the line light source provided on the same substrate as the light receiving element is transmitted by the light guide. As a result, the document is guided to a portion facing the lens body, so that the number of components can be reduced and assembly can be facilitated while improving the S / N ratio and the image quality.

The image sensor according to the third aspect of the present invention has a first surface which is a plane parallel to the light that goes straight from the line light source to a portion facing the lens body of the original, and a curved surface which faces the first surface. Since a light guide having two surfaces is used, of the light emitted from the line light source, a component that goes straight to the original is:
It goes straight to the original along the first surface, and the other components are curved second
Since the light is reflected by the surface and travels in the light guide, the entire light emitted from the line light source can be reduced in reflection, loss due to reflection can be reduced, and the S / N ratio can be improved to improve image quality. Can be.

In the image sensor according to the fourth aspect of the present invention, since the light-emitting end of the light guide is interposed in the space between the lens body and the document, the intrusion of foreign matter into the space is prevented, and It is possible to prevent an error from occurring in the grayscale information, improve the reading accuracy, and improve the image quality.

In the image sensor according to the fifth aspect of the present invention, an inclined surface for reflecting a component of light traveling in the light guide parallel to the original toward the original is formed at the exit side end, so that the light from the line light source is emitted. It can be used efficiently, thereby improving the image quality, reducing power consumption, and saving energy.

In the image sensor according to the sixth aspect of the present invention, since the light guide is formed of a resin molded product, a light guide having a complicated shape can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a main part of an image sensor according to Embodiment 1 of the present invention;

FIG. 2 is a front view showing the light guide of FIG. 1;

FIG. 3 is a configuration diagram illustrating a main part of an image sensor according to a second embodiment of the present invention;

FIG. 4 is a configuration diagram illustrating a main part of an image sensor according to Embodiment 3 of the present invention;

FIG. 5 is a configuration diagram showing a main part of an image sensor according to Embodiment 4 of the present invention.

FIG. 6 is a configuration diagram showing a main part of an image sensor according to a fifth embodiment of the present invention.

FIG. 7 is an enlarged view showing the light guide of FIG. 6;

FIG. 8 is a configuration diagram showing a main part of an image sensor according to a sixth embodiment of the present invention.

FIG. 9 is a configuration diagram showing a main part of an image sensor according to a seventh embodiment of the present invention.

FIG. 10 is a configuration diagram illustrating an example of a conventional image sensor.

FIG. 11 is a front view showing the light guide of FIG. 10;

FIG. 12 is a side view of FIG.

FIG. 13 is a configuration diagram showing another example of a conventional image sensor.

FIG. 14 is a configuration diagram showing still another example of a conventional image sensor.

[Explanation of symbols]

3 original, 5 light emitting diode (point light emitting element), 8 sensor IC (light receiving element), 9 rod lens array (lens body), 21, 22, 23, 24, 25, 26, 27
Light guide, 21a recess, 23a, 24a, 25a, 26
a, 27a Outgoing end, 23b, 26b First surface, 2
3c, 6c Second surface, 25b, 26d, 27b Inclined surface.

Claims (6)

[Claims] 1. A plurality of point light emitting elements which are arranged linearly and emit light for irradiating an original, a light receiving element which receives reflected light from the original, and a light receiving element which receives reflected light from the original And a plurality of concave portions having a curved surface such that light from the point light emitting element is vertically incident thereon and covering each of the point light emitting elements, and light from the point light emitting element is provided. And a light guide for guiding the light to the original by internal reflection. 2. A substrate, a line light source provided on the substrate and emitting light for irradiating a document, and a light reflected from the document provided on the substrate at a distance from the line light source. A light receiving element that receives light from the original, a lens body that forms an image of reflected light from the original on the light receiving element, at least one of the outer peripheral surfaces is formed of a curved surface, and the light from the line light source is reflected internally by the internal reflection. An image sensor comprising: a light guide that guides a document to a portion facing the lens body. 3. The first light guide is a plane parallel to light traveling straight from the line light source to a portion of the document facing the lens body.
3. The image sensor according to claim 2, wherein the image sensor has a surface and a second surface that is a curved surface facing the first surface. 4. A line light source for emitting light for irradiating an original, a light receiving element receiving reflected light from the original, a lens body for forming an image of the reflected light from the original on the light receiving element, A light guide that has an emission side end portion interposed in a space between the lens body and the document and guides light from the line light source to the document by internal reflection. Image sensor. 5. The image sensor according to claim 4, wherein an inclined surface is formed at an output end of the light guide so as to reflect a component of light traveling in the light guide parallel to the document toward the document. . 6. The image sensor according to claim 1, wherein the light guide is formed of a resin molded product.