JP3021120B2 - Image sensor - Google Patents

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 a facsimile, an optical character reader and the like.

[0002]

2. Description of the Related Art In a conventional general image sensor, a transparent cover opposed to an object to be imaged is mounted on an upper portion of a frame, and a light emitting element for irradiating light to the object to be imaged, An optical system for converging light reflected from the optical system, a light receiving element for receiving light from the optical system, a light emitting element, and a substrate on which the light receiving element is mounted. The substrate was fixed to a frame, and the surface of the substrate was coated with a green resist.

[0003]

In the conventional image sensor described above, since the surface of the substrate is green, the efficiency of reflection of the light emitted from the light emitting element on the substrate is low, and the amount of light radiated to the object to be imaged is reduced. In order to increase, the current value must be increased or the performance of the light emitting element must be increased.If the current value is increased, the power consumption increases, and if a high performance light emitting element is used, There was a problem of raising the overall cost.

[0004] The present invention has been made in view of the above problems, and has as its object to provide an image sensor which does not increase the cost and has a small light amount loss.

[0005]

According to the image sensor of the present invention, a transparent cover opposed to an object to be imaged is mounted on a frame, and a light emitting element for illuminating the object with light is provided in the frame. , An optical system for collecting the reflected light from the object to be imaged, and an optical system for receiving the light from the optical system
In those of and a light receiving element, the light emitting element and
The light receiving element is mounted on the same substrate placed in the frame.
The peripheral surface of the light emitting element on the substrate is colored with good light reflection efficiency, and the peripheral surface of the light receiving element is colored with low light reflection efficiency.

In the image sensor according to the present invention, even when the light emitted from the light emitting element hits the peripheral surface of the light emitting element on the substrate , the light is reflected in a color having good light reflection efficiency , so that the light is efficiently reflected, and the light amount loss is considerably reduced. Irradiation is performed on the imaging target without any change. Next, the light reflected by the imaging target is received by the light receiving element through the optical system. But the base
Since the peripheral surface of the light receiving element on the plate has a color with low reflection efficiency, it is possible to prevent adverse effects on light receiving characteristics due to the occurrence of irregular reflection and the like.

[0007]

The present invention will be described in more detail with reference to the following examples. FIG. 1 is a cross-sectional view of an image sensor showing one embodiment of the present invention. In this image sensor,
Transparent cover (glass cover) 12 on top of frame 11
Is installed. In a frame 11, a substrate 15 on which a light emitting element (eg, an LED chip) 13 and a light receiving element (eg, a photodiode chip) 14 are mounted, and a glass cover 12
A rod lens array 16 which is an optical system for condensing light reflected from the upper document W is arranged.

The lower surface of the substrate 15 is pressed upward by a U-shaped curved spring 17 as an elastic member provided at the lower portion of the frame 11, and the upper surface is pressed against protruding walls 11 a and 11 b formed on the inner wall of the frame 11. Is fixed by being. Thereby, the upper surface of the substrate 15 having the light receiving element 14 serves as a reference when fixing, and the focusing of the light receiving element 14 on the rod lens array 16 is improved regardless of the accuracy of the frame 11. The curved spring 17 is not provided over the entire length of the image sensor, but a curved spring having a length substantially half of the entire length is inserted from both ends of the frame 11.

The rod lens array 16 is arranged obliquely so that its optical axis has an inclination angle with respect to the surface of the glass cover 12, and is pressed and fixed to the inner wall of the frame 11 by a lens holder 18. A reflector 19 for efficiently guiding the light from the light emitting element 13 to the original W is provided in the frame 11, and the face of the lens holder 18 facing the light reflector 19 also has a function of reflecting light. Have.

The substrate 15 has the light emitting elements 13 and the light receiving elements 14 arranged in a long line, so that the frame 11 is also long and both ends are covered with a cover. Is also provided with a light reflection plate. Therefore, in the image sensor of this embodiment, a light reflecting plate is provided around the optical path from the light emitting element 13 to the glass cover 12. Colors and materials having high reflection efficiency are used for these light reflection plates.

The substrate 15 includes a first substrate 21 and a second substrate 21.
The first substrate has a copper pattern portion 24 formed on a base material 23 as shown in the enlarged view of FIG.
Further, a green resist 2 is formed on the copper pattern portion 24.
5 and a white resist layer 26 on the green resist 25 only in a region surrounded by the reflector of the light emitting section.
Is formed. The light emitting element 13 is mounted with the white resist layer 26 of the first substrate 21 as a background, and the light receiving element 14 is mounted with the green resist layer 25 of the first substrate as a background.

In this image sensor, the light emitting element 13 is located directly below the glass cover 12, and light reflecting plates 18 and 19 are provided around the light path. The surface of the substrate 15 near the light emitting element 13 is white. The light receiving element 14 is located on the optical axis of the rod lens array 16 and the surface of the substrate 15 near the light receiving element 14 is green. Therefore, the light emitted from the light emitting element 13 is reflected by the white resist 26, and is applied to the document reading position of the glass cover 12 while being repeatedly reflected by the light reflecting plates 18, 19 and the like several times.
Thereafter, the light reflected by the original W is transmitted to the rod lens array 1.
6, the light is condensed, received by the light receiving element 14, and converted into an electric signal. At this time, the light irradiated on the green resist 25 other than the light receiving element 14 is absorbed by green,
This prevents the occurrence of irregular reflection from adversely affecting light receiving characteristics.

[0013]

According to the present invention, a light emitting element and a light receiving element
The light-receiving element is mounted on the same substrate, and the surface around the light-emitting element of this substrate is colored with good reflection efficiency (e.g., white).
The surrounding surface as a color with low reflection efficiency (for example, green).
Therefore, the following effects can be obtained. (1) The light emitting element and the light receiving element are mounted on the same substrate
Therefore, the number of parts is reduced, and the cost can be reduced. (2) To reduce light loss from the light emitting element to the imaging target
And the light receiving characteristics
Can be prevented from being adversely affected.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an image sensor according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of a substrate of the image sensor of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Frame 12 Glass cover 13 Light emitting element 14 Light receiving element 15 Substrate 16 Rod lens array 18, 19 Light reflector 25 Green resist 26 White resist

Claims (1)

(57) [Claims] A transparent cover facing a subject to be imaged is attached to a frame, and a light emitting element for irradiating light to the subject to be imaged and a light reflected from the object to be collected are confined in the frame. an optical system, an image sensor and a <br/> light receiving element for receiving light from the optical system, the light emitting element and the light receiving element is disposed in the frame
An image sensor mounted on one substrate, wherein a peripheral surface of a light emitting element on the substrate is colored with good light reflection efficiency, and a peripheral surface of the light receiving element is colored with low light reflection efficiency.