JPS6236959A - Picture reader - Google Patents

Abstract

PURPOSE:To attain high speed reading by providing a light selective transmitting thin plate reflecting a visual light and transmitting an infrared ray between a linear light source and an original and making the reflected visual light in the thin plate together with the reflected infrared ray from the original into a graded index fiber array. CONSTITUTION:An optical sensor 1 comprising photoconductive conductors made of such as CdS, CdSe or solid solution CdS-CdSe is formed in the main scanning direction in the density of, e.g., 8 elements/mm by 1728 elements on an A4 size. The slight selective transmitting thin plate 4 reflecting the visual light and transmitting the infrared ray of 1-3mum is placed between the original 6 and the liner light source 5 including a visual light component and consisting essentially of infrared-ray components. A bias light 8 being a part of the visual light reflected in the thin plate 4 and the infrared-ray 3 from the original 6 after the transmission are made incident on the graded index optical fiber array 2, the image of the original is formed on an optical sensor 1 and the steady-state visual light as the bias light is irradiated to the sensor 1. This invention utilizes that the optical current of the photoconductive optical sensor is reduced by the irradiation of infrared-ray and the reading is attained in a remarkably higher speed than a conventional speed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image reading device that is capable of high-speed reading and has the same dimensions as the width of a document used in various office automation equipment such as a facsimile machine.

Conventional technology Conventionally, in this type of image reading device, a sensor using a CdS-CdSe solid solution with a large photocurrent and a simple circuit configuration has been put into practical use. 1 in plate (8 elements/cylinder, 1728 elements)
The disadvantage was that the reading speed was slow at about 0 m sec/71 ine. Therefore, for example,
As shown in No. 181751, an improvement was made to enable high-speed reading by adding bias light to the structure shown in FIG.

That is, the original 6 is irradiated with the linear light source 5, and the reflected light 3
In order to improve the optical response speed of the optical sensor 1, the light from a separately provided linear light source 9 is biased when the image of the image is formed on the optical sensor 1 by the focusing fiber array 2 and the information of the document is read. By directly irradiating the light 8 onto the optical sensor and superimposing it on the reflected light 3 from the original document,
It has a structure that increases the response speed of the optical sensor and enables high-speed image reading.

That is, when a photoconductive thin film such as CdS, CdSe, or solid solution CdS-CdSe is used as the optical sensor 1, the response speed is about 5 m5 ec, and when bias light is added to this sensor, //! The speed can be increased to about ~4.

Problems that the invention aims to solve However, with the conventional method, even when bias light is irradiated, the light response speed is about 1 m5 ec, and the only way to increase it faster is to make the light source brighter. There was a problem.

For example, an expensive yellow-green LED can be used as a biased light source.
There were also problems in terms of cost, as two arrays were used.

An object of the present invention is to provide an image reading device that uses a single linear light source and can easily perform high-speed reading.

Means for Solving the Problems The present invention provides a light-selective thin plate that reflects visible light and transmits infrared light between a linear light source and an original, and transmits light as well as infrared light reflected from the original. This structure enables high-speed reading by allowing visible light reflected from a selectively transmitting thin plate to enter a focusing fiber array.

Function The present invention utilizes the phenomenon in which the photocurrent of a photoconductive optical sensor is reduced by irradiation with infrared light in an appropriate wavelength range, and image signals can be detected at high speed.

Embodiment FIG. 1 is a cross-sectional view in the sub-scanning direction showing an embodiment of the image reading device of the present invention.
The optical sensor 1 made of a photoconductor such as CdSe is formed with 1728 elements in the main scanning direction at a density of, for example, 8 elements/square on an A4 size sheet. A light-selective transmissive thin plate that reflects visible light and transmits infrared light of 1 to 3/1 m is provided between a linear light source 6 containing mainly infrared light components and 5-base visible light components and document 6. Put 4. Bias light 8, which is a part of the visible light reflected by this thin plate 4, and infrared reflected light 3 having a wavelength of about 1 to 3/1 m from the original 6 after passing through, enter the light-focusing fiber array 2, It has a structure in which an image of a document is formed on the optical sensor 1 and constant visible light as bias light is irradiated.

Here, the light intensity of the bias light 8 is 1d, ccis.

In the case of an optical sensor mainly composed of CdSe or solid solution CdS-CdSe, one side of the optical sensor has about 30 to 300 lux. The photocurrent required by the reading circuit can be obtained1
The amount of irradiated infrared light can be smaller if the infrared light is less than oo lux. The amount of infrared light with a wavelength of about 1 to 37 zm from the linear light source 5 is such that the reduction in photocurrent obtained by imaging the reflected light 3 from the white background of the document 6 on the optical sensor 1 is as follows, assuming that the steady photocurrent is 100. 50 or more. This reading device can read the white and black signals of a document at high speed. Conventionally, 5 m
The speed of about sec/7ins is 1/10~1/2o
It can be read with 6 high speeds.

Here, the linear light source may be a W lamp with a high luminous efficiency of about 1 to 3 meters and is inexpensive.

Effects of the Invention As described above, according to the present invention, there is provided an image reading device that can be configured using one linear light source and a selectively transparent thin plate.
Therefore, it is inexpensive and can read images at high speed, making it extremely useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an image reading device according to an embodiment of the present invention, and FIG. 2 is a sectional view of a conventional image reading device. DESCRIPTION OF SYMBOLS 1... Optical sensor, 2... Light focusing fiber array, 3... Reflected light, 4... Light selectively transmitting thin plate, 6... ... Linear light source, 6...
...Original, 8...Bias light, 9...
Bias light source.

Claims (3)

[Claims] (1) It has an optical sensor array formed on a substrate, a linear light source that illuminates the original, and a focusing fiber array that focuses reflected light from the original on the optical sensor array, and the linear light source and the original A light-selective transmissive thin plate that reflects visible light and transmits infrared light is provided between the fiber array, and the reflected infrared light from the document and the visible light reflected from the selectively transmissive thin plate are transmitted to the focusing fiber array. What is claimed is: 1. An image reading device characterized in that the image reading device is configured such that the light is incident on the image reading device. (2) The image reading device according to claim 1, wherein the optical sensor array is composed of optical sensors mainly made of CdS, CdSe, or solid solution CdS-CdSe. (3) On the optical sensor surface, when the photocurrent due to reflected visible light is taken as 100, the reduction in photocurrent due to the maximum intensity of reflected infrared light from the document is 50 or more. The image reading device according to either item 1 or item 2.