JPH0365709B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention provides a unidirectional light-transmitting plate that transmits light from a light source and blocks reflected light from the original, thereby blocking unnecessary reflected light from the original, and providing a photoelectric conversion unit for use in a photoelectric conversion unit. The present invention relates to a document reading device that stabilizes the amount of incident light.

(Prior Art) As a conventional color document reading device with a blinking light source, there is one shown in FIG. 1, for example. This color document reading device has light sources 2a and 2 that illuminate the document 1.
b, 2c (for example, each light source uses a red lamp 2a, a green lamp 2c, and a blue lamp 2c)
, a platen glass 3 that transmits the light source light, and a light source 2
a, 2b, and 2c in the direction of the original 1, and a reflector 4 (having a slit 4) that reflects the light from the original 1 for each raster through a slit 4a and a lens 9.
an image sensor 5 for reading signals through the image sensor 5; a storage section 6 for storing signals read by the image sensor 5; and a storage section 6 for storing signals read by the image sensor 5; , or an encoding unit 7 that performs encoding based on the MR (modified read, two-dimensional band compression) method, and a MODEM 8 that modulates the encoded signal and sends it to the line.

To explain the operation in the above configuration,
When a reading command is output, a plurality of light sources 2a, 2
b, 2c sequentially irradiate the original 1, and the red of the original 1,
The reflected light of each color component of green and blue is received by the image sensor 5 via the lens 9, and the content of the document is read by converting it into an electrical signal. The read signal is once stored in the storage section 6, and then encoded by the encoding section 7 based on the MH method or the MR method, and the encoded signal is modulated by the MODEM 8 and sent to the line.

However, in the conventional color document reading device, the document 1 is scanned by a plurality of light sources 2a at different positions.
2b and 2c, the width of the platen glass 3 is wider than the width required for the image sensor 5 to read the document contents, so the amount of reflected light on the document changes depending on the condition of the document surface. Then, the total amount of light irradiated on the document changes, and as a result, the output of the image sensor may change.

(Objects and Structure of the Invention) The present invention has been made in view of the above, and it is an object of the present invention to keep the amount of light irradiated on the document constant even if the amount of reflected light changes depending on the document, and to obtain stable output from an image sensor. Therefore, a light source that illuminates the document surface,
In a document reading device that reads an image of the reading area and includes an optical system that images a reading area of the document surface and a photoelectric conversion unit disposed on the imaging surface of the optical system,
The light source is disposed between the light source and the document irradiated by the light source, has a width large enough to transmit the reflected light from the reading area, and partially transmits the document irradiation light from the light source. It has a slit section made of a unidirectional translucent plate that blocks light reflected from the document surface, and guides the reflected light from the reading area of the document surface through the slit section to an optical system that images the document surface. The object of the present invention is to provide a document reading device in which light enters and reads a photoelectric conversion section disposed on an image forming surface of the optical system.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

(Embodiment) FIG. 2 shows an embodiment of the present invention. The same parts as in FIG. The slit portion 3a has a width that allows the reflected light to pass through.
It is covered with unidirectional light transmitting plates 10a and 10b, except for. Unidirectional transparent plates 10a, 10b
For example, the mirror may be a so-called magic mirror, and has the property of transmitting light from the light sources 2a, 2b, and 2c with high illuminance, but blocking light from the original side with low illuminance. have

In the above configuration, when the red, green, and blue light sources 2a, 2b, and 2c are sequentially turned on by outputting a reading command, the original 1 is irradiated through the magic mirrors 10a, 10b and the platen glass 3, and the original 1 is illuminated. The reflected light from the reading area is outputted through the slit portion 3a of the platen glass 3 and the slit 4a of the reflector 4, and enters the image sensor 5 via the lens 9. The read signal photoelectrically converted into an electric signal by the image sensor 5 is stored in the storage unit 6, encoded by the encoder 7, modulated by the MODEM 8, and sent out in the same manner.

In the above embodiments, one side of the platen glass is covered with a magic mirror, but it is also possible to leave a slit portion of the platen glass and cover other parts with a magic mirror.

(Effects of the Invention) As described above, according to the present invention, a part of the slit serves as a slit that transmits the reflected light from the reading area of the document surface, and transmits the document irradiation light from the light source, and allows the reflected light from the document surface to pass through. Since a unidirectional light-transmitting plate that blocks light is provided, even if the amount of reflected light changes depending on the original, the amount of light irradiated on the original can be kept constant, and stable output can be obtained from the image sensor.

[Brief explanation of drawings]

FIG. 1 is a structural explanatory diagram of a conventional document reading device, and FIG. 2 is a structural explanatory diagram of a document reading device according to the present invention. Explanation of symbols, 1... Original, 2a, 2b, 2c... Light source, 3... Platen glass, 5... Image sensor,
10a, 10b...unidirectional light transmitting plate (magic mirror).

Claims (1)

[Scope of Claims] 1. A light source that illuminates a document surface, an optical system that captures an image of a reading area on the document surface, and a photoelectric conversion section that is arranged on an imaging surface of the optical system, and that captures an image of the reading area. In the original reading device, the light source is disposed between the light source and the original illuminated by the light source, has a width sufficient to transmit reflected light from the reading area, and a portion of the original is irradiated with the original from the light source. It has a slit portion made of a unidirectional transparent plate that transmits irradiated light and blocks reflected light from the document surface, and directs the reflected light from the reading area of the document surface to the document surface through the slit portion. A document reading device characterized in that the document is guided to an optical system for capturing an image, and enters and reads a photoelectric conversion section disposed on an image forming surface of the optical system.