JPH07203124A - Close contact type image sensor - Google Patents

Abstract

PURPOSE:To reduce number of boards and to make the mounting operation efficient by mounting an LED array light source and a sensor element onto a common board. CONSTITUTION:An LED array light source 22 is mounted on a board on which a sensor element 36 is mounted, and an optical guide plate 24(40) to guide a light emitted from the LED array light source 22 is arranged so that its one terminal comes in the vicinity of the LED array light source 22 and the other terminal comes in the vicinity of an original read position P. The optical guide plate 24 is simply obtained by processing an acrylic resin and the middle of the plate 24 is folded at, e.g. an angle of 90 deg.. The LED array light source 22 and the optical guide 24 are sealed by a UV curing resin. The light emitted from the LED array light source 22 is made incident onto one terminal of the optical guide and led in the vicinity of the original read position while being reflected in the inside of the guide.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type image sensor used as a document reading device in a small facsimile, a copying machine or the like.

[0002]

2. Description of the Related Art FIG. 3 is a schematic sectional view of a conventional contact image sensor. FIG. 3 shows a cross section of the contact image sensor taken along a plane perpendicular to the longitudinal direction (main scanning direction). The contact image sensor includes a frame 52, a document surface glass 54, an LED array light source 56, a SELFOC lens array 58, a mounting substrate 62, and a photoelectric conversion unit 64. The photoelectric conversion means 64 includes a sensor substrate 64b on which a large number of sensor elements 64a are formed.

The frame 52 holds the respective constituent members in a fixed positional relationship. The document surface glass 54 is provided above the frame 52, and the document slides on the document surface glass 54.

The light source 56 irradiates the original with light, and is provided at the center of the frame 52. The light source 56 is
It has a substrate 56a and a large number of light emitting elements 56b formed of LEDs. For example, for A4 size, 3
Two light emitting elements 56b are arranged on the substrate 56a along the main scanning direction.
Implemented on. The light source 56 is arranged such that the substrate 56a is tilted by approximately 45 ° with respect to the original surface glass 54, and the light emitting element 56b is kept at a constant distance from the original reading position P. The reason why the light emitting element 56b has a certain distance is that if the light emitting element 56b is too close to the document surface glass 54, the uniformity of the illuminance at the document reading position P deteriorates, and only just above the light emitting element 56b becomes extremely bright. Because it will be. The light emitting element 56b is resin-sealed by potting in order to improve environment resistance such as humidity resistance and to protect the bonding wire 56c. The resin 56d has a lens effect to improve the directivity of light.

Further, the SELFOC lens array 58 is
The light source 56 emits light, and the reflected light reflected by the document at the document reading position P is focused on the sensor element 64a, and is provided at a substantially central portion of the frame body 52. The mounting board 62 is provided below the frame body 52.
A sensor substrate 64b on which a large number of sensor elements 64a are formed along the main scanning direction is arranged on the upper side. Incidentally, FIG.
In, 66 is a spacer.

To read a document placed on the document surface glass 54, first, the light emitting element 56b of the light source 56 is caused to emit light, and the light is applied to the document reading position P. Then, the reflected light reflected by the document at the document reading position P is focused on the sensor element 64a by the SELFOC lens array 58. The sensor element 64a reads an image for one line from the reflected light, converts it into an electric signal, and outputs it. Then, as the document slides in the sub-scanning direction, the sensor element 64a reads an image line by line, and the entire image of the document is captured as an electric signal.

[0007]

As shown in FIG. 3, in the conventional contact image sensor, in order to make the illuminance of light at the document reading position P appropriate and uniform, a light source 56 is used.
A substrate 56a for mounting the above is disposed under the document surface glass 54 with an inclination of about 45 °. Separately from this, a substrate 62 on which the photoelectric conversion means 64 is mounted is provided below the SELFOC lens array 58. As described above, since the two substrates 56a and 62 are required in one frame, the cost is increased, and the mounting process of the elements on each substrate is performed separately, which complicates the manufacturing process. There's a problem. The present invention has been made based on the above circumstances, and an object of the present invention is to provide a contact-type image sensor capable of simplifying the mounting process.

[0008]

The invention according to claim 1 is
A light source in which a plurality of light emitting elements are arranged along the main scanning direction,
A contact type image sensor having an optical system for converging light from the light source reflected by a document and a photoelectric conversion means for converting the light condensed by the optical system into an electric signal, wherein the light source and the photoelectric conversion means are provided. Is provided on the same substrate, and light guide means for guiding the light emitted from the light source to the vicinity of the reading position of the document is provided.

According to a second aspect of the invention, in the first aspect of the invention, the light guide means is made of a transparent resin.

According to a third aspect of the invention, in the second aspect of the invention, the transparent resin is acrylic.

According to a fourth aspect of the present invention, in the first, second or third aspect of the invention, the light guide means has a bent shape in a cross section perpendicular to the main scanning direction. .

[0012]

According to the invention described in claim 1, since the light source is provided on the same substrate as the substrate on which the sensor element is mounted, the distance between the light source and the document reading position becomes longer than the conventional one. However, since the newly provided light guide means guides the light emitted from the light source to the vicinity of the original without waste,
Sufficient illuminance can be obtained at the original reading position.

According to a second aspect of the present invention, by the above configuration,
By configuring the light guide means from a transparent resin, the light emitted from the light source and incident on one end of the light guide means reaches the other end without waste while reflecting inside the resin due to the high refractive index of the resin.

According to a third aspect of the present invention, according to the above configuration,
By forming the light guide means from acrylic which is a transparent resin, the light guide means can be easily processed into a desired shape, and the overall cost can be kept low.

According to a fourth aspect of the present invention, according to the above configuration,
Since the light entering the inside of the resin travels while being reflected by the surface of the resin, the light can be guided from one end to the other end even if the resin is bent. By being able to bend the resin in this way, the degree of freedom in arranging the components is increased.

[0016]

EXAMPLES Examples will be described below with reference to the drawings. FIG. 1 is a schematic sectional view of a contact image sensor according to a first embodiment of the present invention, and FIG. 2 is a schematic sectional view of a contact image sensor according to a second embodiment of the present invention. 1 and 2
Shows a cross section perpendicular to the longitudinal direction (main scanning direction) of the contact image sensor.

The contact type image sensor of FIG.
A document surface glass 14, an LED array light source 22 serving as a light source, a light guide plate 24 for guiding light from the LED array light source 22 to a document reading position, a SELFOC lens 32 as an optical system, and a mounting substrate 34. And the sensor element 3
6a is formed on the sensor substrate 36. This contact image sensor is for A4 size and has a length of about 230 mm in the main scanning direction.

The frame 12 holds the respective constituent members in a fixed positional relationship. The frame 12 is obtained by extruding a metal such as aluminum or stainless steel. The document surface glass 14 is provided on the upper portion of the frame body 12, and the document slides on the document surface glass 14.

The LED array light source 22 includes 16 light emitting elements 22a made of LEDs and bonding wires 22 for the light emitting elements 22a.
b, these light emitting elements 22a are
Are mounted in a line on the same substrate 34 on which is mounted at about 14 mm intervals in the main scanning direction.

The light guide plate 24 includes 16 light emitting elements 22.
The light emitted by a is guided, one end thereof faces the light emitting element 22a, and the end on the light extraction side is arranged near the SELFOC lens array 32. As a material for the light guide plate 24, a transparent resin such as an acrylic resin is used. Acrylic resin has good workability,
It is very inexpensive. The processing of the light guide plate 24 is performed by molding or cutting, and the light guide plate 2 is processed.
4 does not need to be subjected to any special end surface treatment. The light guide plate 24 of the present embodiment includes a substrate 34 arranged below the frame body 12.
In order to guide the light from the light source 22 mounted above to the reading position P of the original, as shown in FIG.
It is bent at an angle of 0 °.

The optical coupling resin 26 is used for the light emitting element 22.
a and the light guide plate 24 so that the coupling loss of light is reduced, that is, the light emitted by the light emitting element 22a is efficiently incident on the light guide plate 24. It is for sealing the gap with the plate 24. As the optical coupling resin 26, for example, a transparent UV curing resin is used. The UV curable resin is characterized in that it can be easily cured by irradiating it with ultraviolet rays.

The SELFOC lens array 32 is a frame body 12.
The light emitting element 22 of the light source 22 is provided substantially at the center of the
The reflected light reflected by the document at the document reading position P is focused on the sensor element 36a. The SELFOC lens array 32 is configured by bundling a large number of optical fibers. As the SELFOC lens array 32, SLA20D manufactured by Nippon Sheet Glass Co., Ltd. having a fiber diameter w of 0.6 mm and a focal length (TC (total conjugate) length) of 9.1 mm is used. The TC length corresponds to the distance from the document reading position P to the sensor element 36a. In FIG. 1, 38 is a spacer.

The sensor element 36a formed on the sensor substrate 36 is composed of a photodiode and a blocking diode. The photodiode is for converting the reflected light from the document that enters through the SELFOC lens array 32 into an electric signal, and the blocking diode is a switching element for taking out electric charges corresponding to image information from each photodiode. It functions as.

As described above, in this embodiment, by providing the bent light guide plate 24, the light source 22 and the sensor substrate 36 can be mounted on the common substrate 34. As a result, the substrate dedicated to the light source, which is required in the conventional contact-type image sensor, becomes unnecessary, and the cost can be reduced accordingly. Further, since the steps such as bare chip die bonding, wire bonding, and resin potting can be collectively performed on the light emitting element 22a and the sensor substrate 36, there is an advantage that the steps can be simplified and the production efficiency can be improved. Further, the substrate 34
By patterning the leads of the light source 22 in advance, there is also an advantage that it is not necessary to take out the leads of the light source.

Next, the operation of the contact image sensor of this embodiment will be described. First, the document is placed on the document surface glass 14 with the document surface facing down, and the LED array light source 22
When the light emitting element 22a of No. 2 is made to emit light, the light efficiently enters the light guide plate 24 via the optical coupling resin 26.
The light travels along the path indicated by the dotted line in FIG. 1 while being repeatedly reflected inside the light guide plate 24, and is efficiently guided to the vicinity of the SELFOC lens array 32 by the light guide plate 24. Of the light extracted from the end surface of the light guide plate 24, a part of the light directly illuminates the original reading position P on the original surface glass 14, and the other part thereof illuminates the frame 12.
It is reflected by and irradiates the reading position P of the document. It should be noted that sufficient light intensity can be obtained at the reading position P of the document only by the light directly radiating the document from the end surface of the light guide plate 24.

The reflected light reflected by the document at the document reading position P is focused on the sensor element 36a on the sensor substrate 36 by the SELFOC lens array 32. The sensor element 36a reads an image for one line from the reflected light, converts it into an electric signal, and outputs it. And
As the document slides in the sub-scanning direction, the sensor element 36a reads an image line by line, and the entire image of the document is captured as an electric signal.

In the contact image sensor of this embodiment, the light guide plate for guiding the light emitted from the light emitting element of the light source is provided, and the space between the light emitting element and the light guide plate is sealed with the optical coupling resin. Since the light emitted from the light emitting elements can be guided to the vicinity of the SELFOC lens array without waste, even if the number of light emitting elements is reduced to about half compared to the conventional one, the same illuminance can be obtained at the document reading position. be able to. Therefore, by reducing the number of light emitting elements as compared with the conventional one, it is possible to reduce the cost without degrading the performance. Incidentally, in the contact type image sensor of the present embodiment, since a light guide plate is newly provided, there is a concern about the cost of this light guide plate.
For example, if a material such as acrylic is used, the cost of the light guide plate is not a problem.

By the way, conventionally, it has been necessary for the light emitting element to be resin-sealed by potting in order to improve the environment resistance and protect the bonding wire. But,
In this embodiment, since the space between the light emitting element and the light guide plate is sealed with the coupling resin, the optical coupling resin has the functions of improving the environmental resistance and protecting the bonding wires as described above. Therefore, it is not necessary to perform resin sealing of the light emitting element by potting as in the related art.

Further, in this embodiment, the LED array light source 2 is used.
2 is provided on the same substrate 34 as the sensor substrate 36, and its light is guided by the light guide plate 24, so that the light source is tilted at an angle of about 45 ° with respect to the document surface glass and is constant from the document reading position. It is possible to reduce the height of the contact-type image sensor as compared with the conventional one in which the distance is maintained. For example, as a SELFOC lens array, the conventional fiber diameter w is 0.9 mm and TC
Although SLA20B manufactured by Nippon Sheet Glass having a length of 14.4 mm was used, in this example, the fiber diameter w was 0.6.
mm Sla2 made by Nippon Sheet Glass with TC length of 9.1 mm
By using 0D, the distance from the document reading position to the sensor element is shortened, and the contact-type image sensor can be made thinner and more compact. Further, the selfoc lens array is cheaper as the diameter of the optical fiber is smaller, so that the cost can be further reduced.

FIG. 2 is a schematic sectional view of the second embodiment of the present invention. In the figure, the same parts as those of the contact image sensor of FIG. The second embodiment differs from the first embodiment in FIG. 1 in that the light guide plate 40 has a substantially flat cross section.

The present invention is not limited to the above embodiments, but various modifications can be made within the scope of the gist thereof.

[0032]

As described above, according to the present invention, the light emitting element which is the light source and the sensor substrate which is the photoelectric conversion means are provided on the same substrate, which is required in the conventional contact type image sensor. The board dedicated to the light source is not required, and the cost can be reduced, and the mounting work of the light emitting element and the sensor board can be performed collectively, so that the production efficiency can be improved, and by providing the light guide plate, the light source is provided. Since the light emitted from the can be effectively guided to the original, it is possible to provide a contact-type image sensor that requires a small number of light emitting elements.

Further, by forming the light guide plate from a transparent resin such as acrylic resin, the shape of the light guide plate can be easily processed into, for example, a shape in which the cross-sectional shape is bent at a substantially right angle, and the degree of freedom in its arrangement is high. It is possible to provide a contact image sensor in which

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a contact image sensor according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a contact image sensor according to a second embodiment of the present invention.

FIG. 3 is a schematic sectional view of a conventional contact image sensor.

[Explanation of symbols]

 12, 52 Frame 14, 54 Original surface glass 34, 56a, 62 Substrate 22a, 56b Light emitting element 24, 40 Light guide plate 26 Optical coupling resin 32, 58 Selfoc lens array 36a, 64a Sensor element

Claims (4)

[Claims] 1. A light source in which a plurality of light emitting elements are arranged along a main scanning direction, an optical system for focusing light from the light source reflected by a document, and light focused by the optical system into an electric signal. In a contact image sensor having photoelectric conversion means for converting, the light source and the photoelectric conversion means are provided on the same substrate, and light guide means for guiding the light emitted by the light source to the vicinity of the reading position of the document is provided. A contact image sensor characterized in that 2. The contact type image sensor according to claim 1, wherein the light guide means is made of a transparent resin. 3. The contact type image sensor according to claim 2, wherein the transparent resin is acrylic. 4. The contact type image sensor according to claim 1, wherein the light guide unit has a bent shape in a cross section perpendicular to the main scanning direction.