JPH057279A - Image sensor - Google Patents

Abstract

PURPOSE:To reduce fabrication processes and to offer a low-cost and small-sized image sensor. CONSTITUTION:A circuit board 2 provided with a light emitting part 4 and a light receiving part 5 and a glass cover 3 are provided on a frame 1. An optical system 6 is pressed/held against/to an optical system mounting wall 1(a) of the frame 1 by means of a lens pressor 7 provided on the frame 1, the light emitting part 4 is arranged so that light from the light emitting part 4 can be made incident to the glass cover approximately vertically and the optical system 6 is arranged so that the optical axis of the optical system 6 can have a tilting angle theta with respect to the face of the glass cover 3. The light emitted from the light emitting part 4 is made incident to an original A on the glass cover 3 approximately vertically, reflected in a diagonal direction at an angle theta, and then passes through the optical system 6, received with the light receiving part 5 and converted into an electric signal.

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 in facsimiles, optical character readers and the like.

[0002]

2. Description of the Related Art A conventional general image sensor is shown in FIG. FIG. 2 is a cross-sectional view of a main part in a plane orthogonal to the scanning direction. In this image sensor, a transparent cover (glass cover) 31 is attached to an upper portion of a frame 30, a substrate 33 for a light emitting portion 32 is attached to a middle portion, and a substrate 35 for a light receiving portion 34 is attached to a lower portion. Further, the optical system (refractive index gradient lens array) 36 is pressed and fixed to the optical system mounting wall 30 a of the frame 30 by the elastic piece 37 provided on the substrate 33. Optical system 3
6 is positioned perpendicular to the glass cover 31 and the substrate 35, and its optical axis is also oriented in the vertical direction. Further, a spherical plastic lens 38 is supported on the light emitting portion 32 by an elastic piece 37.

In such an image sensor, an image pickup object (for example, a document) A is placed on a glass cover 31 for use. The light emitted from the light emitting portion 32 is the plastic lens 3
Then, the original A on the cover 31 is irradiated at an angle of about 45 degrees with respect to the surface of the glass cover 31. The light reflected by the original A perpendicularly to the glass cover 31 is reflected by the optical system 3
After passing through 6, the light is received by the light receiving section 34 located immediately below and converted into an electric signal.

[0004]

In the above conventional image sensor, as can be seen from FIG. 2, the light from the light emitting portion 32 is obliquely incident on the original A, and the reflected light from the original A is incident on the original A. As described above, the optical system 3 is used to move vertically.
Reference numeral 6 is arranged vertically to the glass cover 31 and the substrate 35 (including the light receiving portion 34) which serves as a light receiving surface. With such a configuration, the distance y from the document A to the light receiving surface (to be exact, the light receiving portion 34) is indispensable only for the conjugate length of the optical system 36, which is a main factor that hinders downsizing of the image sensor. .

Further, since the substrate 33 for the light emitting portion 32 must be attached to the frame 30 at an angle to the glass cover 31, and the substrate 35 for the light receiving portion 34 must be attached to the frame 30 in parallel to the glass cover 31, respectively. Unit 32 and light receiving unit 34
Need to be separately manufactured on each of the substrates 33 and 35,
As the number of parts increases, the number of manufacturing steps increases and the cost increases.

Therefore, an object of the present invention is to provide a low-priced and small-sized image sensor while reducing the number of manufacturing steps in order to solve the above problems.

[0007]

In order to achieve the above object, in the image sensor of the present invention, the light emitting portion is arranged in the conventional image sensor so that the light from the light emitting portion enters the transparent cover substantially vertically. The optical system is arranged such that the optical axis of the optical system has an inclination angle with respect to the surface of the transparent cover.

With this configuration, the light from the light emitting portion is incident on the transparent cover almost vertically and is reflected by the object to be imaged on the transparent cover in an oblique direction with respect to the transparent cover, but the optical system is arranged in the reflected light path. Therefore, the reflected light is collected by this optical system, received by the light receiving portion, and converted into an electric signal. Regarding the tilt angle of the optical system, this angle is not specified as long as the optical system can efficiently collect the reflected light from the object to be imaged. This angle is appropriately adjusted so that the optical axis of the optical system is inclined with respect to the surface of the transparent cover according to the application of the image sensor.

[0009]

EXAMPLES The image sensor of the present invention will be described below based on examples. FIG. 1 shows a cross section of a main part of the embodiment. In this image sensor, one substrate 2 is attached to the lower part of an aluminum frame 1, and a glass cover 3 as a transparent cover is attached to the upper part. On the substrate 2, a light emitting portion 4 including an LED chip and the like and a light receiving portion 5 including a photodiode chip and the like are provided in accordance with an appropriate wiring pattern. The optical system (gradient index lens array) 6 is pressed and fixed to the optical system mounting wall 1 a of the frame 1 by a lens holder 7 mounted on the frame 1. In this embodiment, the light emitting section 4 is located vertically below the glass cover 3, and the optical system 6 is oblique so that its optical axis forms an angle θ of about 60 degrees with the surface of the glass cover 3. It is arranged. Further, the light receiving section 5 is located on the optical axis of the optical system 6.

In the image sensor having such a structure, the light emitted from the light emitting portion 4 is the original A which is the object to be imaged on the glass cover 3, as indicated by the alternate long and short dash line in the figure.
To the glass cover 3 in an oblique direction with respect to the glass cover 3, passes through the optical system 6 in the reflected light path, is received by the light receiving section 5, and is converted into an electric signal. It

In the above embodiment, the inclination angle θ of the optical system 6 with respect to the surface of the glass cover 3 is about 60 degrees, but in this case, the substrate serving as the light receiving surface for the reflected light from the original A on the glass cover 3. The distance x to 2 (more precisely, the light receiving section 5) is reduced by about 15% from the conjugate length of the optical system 6, and the image sensor can be reduced accordingly. Further, since the light emitting unit 4 and the light receiving unit 5 are provided on the same substrate 2, the number of substrates to be used can be reduced and the light emitting unit 4 and the light receiving unit 5 can be manufactured at the same time, so that the number of manufacturing steps can be reduced. . When the inclination angle θ is about 60 degrees, the distance x can be shortened by about 15%. However, when the angle θ is other than 60 degrees, the distance x can be shortened with some difference.

[0012]

As described above, in the image sensor of the present invention, the light emitting portion is arranged so that the light from the light emitting portion enters the transparent cover substantially vertically, and the optical axis of the optical system is the transparent cover. Since the optical system is arranged so as to have an inclination angle with respect to the surface, the following effects are obtained. (1) The material size (aluminum) of the frame can be reduced by reducing the frame size based on the downsizing of the image sensor. (2) Since the light emitting unit and the light receiving unit can be provided on the same substrate, the number of substrates to be used is reduced and the number of manufacturing steps is reduced. (3) Due to (1) and (2), cost reduction of the image sensor can be achieved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of an image sensor of the present invention.

FIG. 2 is a cross-sectional view of an essential part showing a conventional image sensor.

[Explanation of symbols]

1 frame 2 substrates 3 glass cover (transparent cover) 4 Light emitting part 5 Light receiving part 6 Optical system (gradient index lens array) A original (imaging target)

Claims (3)

[Claims] 1. A transparent cover on which an object to be imaged is placed, a light emitting unit for irradiating the object to be imaged with light, an optical system for collecting reflected light from the object to be imaged, and light from the optical system. In an image sensor having a light receiving portion for receiving light, the light emitting portion is arranged so that the light from the light emitting portion enters the transparent cover substantially vertically, and the optical axis of the optical system with respect to the surface of the transparent cover. The image sensor is characterized in that the optical system is arranged so as to have a tilt angle. 2. The image sensor according to claim 1, wherein the light emitting portion and the light receiving portion are formed on the same substrate. 3. The image sensor according to claim 1, wherein the light receiving portion is arranged so that the reflected light from the image pickup object is obliquely incident on the light receiving portion.