JPH04311146A - Thin contact image sensor - Google Patents

Abstract

PURPOSE:To offer a thin contact image sensor capable of obtaining a stable image whose shading distortion is reduced by making it possible to reduce the thickness of the sensor even in the case of using a convergent light transmitter array having deep focal depth and long conjugate length. CONSTITUTION:At least one of optical paths in the incident substance distance range of the original (7) side or the image face distance range of the image sensor (1) side is bent by a mirror 5 or 6. The original 7 is irradiated with light from a light source from a position just above the original 7 through the half mirror 5, the reflected light is reflected by the mirror 5 and made incident upon the convergent light transmitter array 4. The direction of an optical path from the light source up to the mirror 5 is allowed to alight with that of the optical path of light projected from the array up to the sensor 1.

Description

[Detailed description of the invention]

0001

[Industrial Field of Application] The present invention relates to an image reading device.
In particular, it relates to the optical system of a contact image sensor.

0002

2. Description of the Related Art Conventionally, a contact image sensor using an LED array, a one-dimensional image sensor, and a convergent light transmitter array has a one-dimensional image sensor 1, a convergent light transmitter array 4, and a convergent light transmitter array, as shown in FIG. The originals 7 to be read were arranged in a vertical line, and the optical axis of the LED array light source 2 was directed obliquely to the optical axis of the sensor.

0003

[Problems to be Solved by the Invention] In the optical system of this conventional contact image sensor, the total height of the device is required to be greater than the focal length of the convergent light transmitter array, and a convergent light transmitter with a long focal length is used. This results in a problem in that the distance in the object image plane increases and the overall size of the device increases.

Furthermore, since the optical axis of the light source is arranged diagonally with respect to the optical axis of the sensor, the optical axes of the two may become misaligned due to the fluttering of the document to be read, and the more the light beam of the light source is narrowed down, the more the light intensity will decrease. The problem was that it changed drastically.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thin contact image sensor that solves the above-mentioned problems.

[0006]

[Means for Solving the Problems] The thin close-contact image sensor of the present invention includes a one-dimensional image sensor, an LED array light source, a circuit board for fixing both, a convergent light transmitting body array, an LED array light source, a half mirror, and a reflecting mirror. It is equipped with

[0007] Then, the incident object distance range on the document side or
It consists of means for bending at least one optical path in the output image plane distance range on the image sensor side using a mirror.

Furthermore, in the present invention, light from a light source is transmitted through a half mirror and irradiated onto an object such as a document from directly above, and the reflected light that is reflected via the same optical path is split by the half mirror to improve focusing. It consists of a means for making the light incident on the light transmitting body array.

The present invention also provides an optical path from a light source to an object such as a document, an optical path until the reflected light from the object such as a document is reflected on a half mirror, and a light path emitted from the half mirror.
It consists of a means for matching the direction of the optical path that is reflected by the reflecting mirror and reaches the image plane on the image sensor.

0010

[Embodiment] Next, an embodiment of the thin contact image sensor of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of an embodiment of the invention. The image of the read document 7 is first bent by 90 degrees by the half mirror 5, and the light beam travels inside the document in a sine curve, and when it is cut to an appropriate length, it enters the convergent light transmitter array 4 where it forms an image. The light emitted from the convergent light transmitter array 4 is bent by 90 degrees again by the reflecting mirror 6 and is erected onto the surface of the one-dimensional image sensor 1 at a position optically equidistant from the original to be read and the convergent light transmitter. Forms a double real image. Further, the illumination of the original to be read 7 is performed by the LED array light source 2 directly above the half mirror 5.

[0011]

[Effects of the Invention] As explained above, the present invention uses a reflecting mirror to bend the imaging optical path in a straight horizontal line.
The use of a converging specular light transmitter array in which the imaging conjugate length becomes longer in order to increase the depth of focus has the effect of obtaining a thin contact image sensor.

[0012] Also, by using a half mirror as one of the reflecting mirrors and illuminating it from directly above, the directions of the optical axis of the sensor and the optical axis of the light source are made to coincide, and the directions of the two optical axes may be changed due to flapping, wrinkles, etc. of the original to be read. This has the effect of obtaining a stable image with less shading distortion than when they do not match.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a thin contact image sensor according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of a conventional contact image sensor.

[Explanation of symbols]

1 One-dimensional image sensor 2 LED array light source 3 Circuit board 4 Focusing optical transmitter array 5 Half mirror 6 Reflector 7　Reading manuscript

Claims (3)

[Claims] 1. A close-contact image sensor using a convergent light transmission array, characterized in that an optical path in at least one of an object distance range on a document side or an image plane distance range on an image sensor side is bent by a mirror. sensor. 2. Light from a light source is transmitted through a half mirror to irradiate an object such as a document from directly above, and the reflected light that is reflected via the same optical path is reflected by the half mirror so as to separate the optical paths, The thin contact image sensor according to claim 1, wherein the light is incident on the convergent light transmitting body array. 3. An optical path from a light source to an object such as a document, an optical path until the reflected light from the object such as the document is reflected on the half mirror, and a light path emitted from the half mirror is reflected by the reflecting mirror. 2. The thin contact image sensor according to claim 1, wherein the direction of the optical path to the image sensor is made to coincide with that of the optical path.