JPH02108363A - Picture reader - Google Patents

Abstract

PURPOSE:To process with a light-receiving element, to minimize the space necessary for a signal transmission, to miniaturize a device, to make immune to a noise and to prevent the deterioration of a signal characteristic by moving the original in the width scanning direction of the original with a contact type image sensor, digitizing a reading signal and sending with a pulse wave by a laser light emitting element. CONSTITUTION:An original 4 placed on an original platen glass 2 of a picture reader is optically read while a contact type image sensor 3 is moved with speed V in a width scanning direction A of the original 4. The read picture information is A/D-converted 10, a digital signal is sent to a laser light-emitting element 11 and a laser pulse wave is outputted from the element 11. The outputted laser light is synthesized with speed 1/2V in the same direction as that of the sensor 3, reflected by a pair of moving mirrors 13 and 14, the light path is converted and a laser light is light-received by a laser light-receiving element 15. The space necessary for signal transmission is minimized, the pulse wave of the laser light received by the element 15 is converted to the digital signal and transmitted to the external part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an image reading device, and particularly to the structure of a document-fixed type image reading device.

[Prior Art] FIG. 2 is a block diagram schematically showing a conventional image reading device. In the figure, 1 is a reading device casing, 2 is a document platen glass provided on the top surface of the reader casing 1, and 3 is a document platen glass provided in the reader casing 1, with the document platen glass 2 placed directly below the document platen glass 2. A contact type image sensor moves in the sub-scanning direction of the document 4 placed on the screen, and 5 is a signal cable that also serves as a power supply cable for transmitting image information of the document 4 obtained by the contact type image sensor 3. Reference numeral 6 designates a signal processing unit disposed within the reader casing 1, which takes in image information transmitted through the signal cable 5 and converts it into an appropriate signal format, and 7 designates a power supply unit for the contact type image sensor 3.

The conventional image reading device is configured as described above, and when the contact type image sensor 3 optically reads the document 4 placed on the document platen glass 2 while moving in the sub-scanning direction A of the document 4, the contact type image sensor 3 optically reads the document 4 placed on the document table glass 2. Image information of the document 4 read by the image sensor 3 is output as an analog signal of voltage strength. The analog signal is transmitted by a signal cable 5 and sent to a signal processing section 6.

[Problems to be Solved by the Invention] However, in the image reading device having the above configuration, the analog signal based on the voltage strength of the image information of the document 4 obtained by the contact type image sensor 3 is transmitted to the signal processing unit 6 via the signal cable 5. Therefore, as the reading speed and resolution of the contact image sensor 3 increases, the number of signal cables 5 that transmit image information from the contact image sensor 3 increases. There was a problem in that the mounting space for routing the 5 was large, and the device could not be made smaller. Further, noise is easily induced through the signal cable 5, and as the signal cable 5 becomes longer, the characteristics of the rising and falling portions of the analog signal output from the contact image sensor 3 deteriorate. Furthermore, there is a problem in that the signal cable 5 may be coated or its core wire may be broken due to the signal cable 5 sliding as the contact image sensor 3 moves.

This invention eliminates the problems of not being able to miniaturize the device, easily inducing noise, degrading the characteristics of analog signals, and causing disconnection accidents, and reducing the space required for signal transmission, thereby making the device more compact. It is an object of the present invention to provide an excellent image reading device that is resistant to noise, eliminates deterioration of analog signal characteristics, and is free from disconnection accidents.

[Means for Solving the Problems] The present invention provides an image reading device that includes a contact type image sensor that optically reads a document, and an A/D converter that converts an analog signal output of the image information read by the contact type image sensor into a digital signal. With D converter.

an image reading section that includes a laser light emitting element that emits a digital signal output by the A/D converter as a pulse wave of laser light, and scans the document in the sub-scanning direction; and a path of the laser light emitted from the laser light emitting element. a mirror that converts the optical path of the laser beam, a laser light receiving element that receives the laser light whose optical path has been changed by the mirror and converts the pulse wave of the laser light into a digital signal, and a laser light receiving element that transmits the digital signal output from the laser light receiving element to an external circuit. A signal processing section having functions is provided.

[Operation] In this invention, when a contact type image sensor optically reads a document on the document platen glass while moving in the sub-scanning direction of the document, the analog signal output of the image information read by the contact type image sensor is A /D converter converts it into a digital signal, and the laser light emitting element sends it out as a pulse wave of laser light.

The optical path of the laser beam is changed by a mirror, received by a laser light receiving element, converted into a digital signal, and sent to a signal processing section.

[Example] FIG. 1 is a block diagram showing an outline of an embodiment of the present invention.

In the figure, the same components as those in the conventional example are given the same reference numerals as those in the conventional example, and the explanation of the redundant components will be omitted. IO is an A/D converter that converts the analog signal output of the image information read by the contact image sensor 3 into a digital signal, and 11 is ^
A laser light emitting element 12 emits the digital signal outputted by the /D converter IO as a pulse wave of laser light, and 12 is formed by integrating the contact type image sensor 3, the A/D converter 10, and the laser light emitting element 11. The image reading unit is disposed within the reading device casing 1 and moves at a speed V in the sub-scanning direction A of the original 4 when reading the original.

Reference numerals 13 and 14 denote a pair of mirrors that change the path of the laser beam emitted from the laser emitting cable 11, and are disposed inside the reader casing 1. The pair of mirrors 13 and 14 move synchronously in the same direction as the image reading section 12 at a speed of 1/2 V. Reference numeral 15 denotes a laser light receiving element fixedly disposed within the reader casing 1, which converts a pulse wave of laser light into a digital signal. te is a power supply cable for the image reading section 12;

In the image reading apparatus configured as described above, the contact image sensor 3 optically reads the original 4 placed on the original platen glass 2 while moving at a speed V in the sub-scanning direction A of the original 4. The analog signal output of the image information read by the contact image sensor 3 is converted into a digital signal by the A/D converter 1O, and the digital signal is sent to the laser light emitting element 11. The laser light emitting element 11 outputs a pulse wave of laser light. The laser light output from the laser light emitting element 11 is reflected by a pair of mirrors 13 and 14 that move synchronously at a speed of 1/2 V in the same direction as the contact image sensor 3, and the optical path is changed, and then the laser light is sent to the laser light receiving element. It is received at 15. The reason why the pair of mirrors 13 and 14 are moved at a speed of 1/2 V in this way is to keep the optical path length of the laser beam constant and prevent attenuation due to diffusion of the laser beam. The laser light receiving element 15 converts the received pulse wave of the laser light into a digital signal and sends it to the signal processing section 6 which processes the digital signal into a signal in the form necessary for transmission to an external circuit (not shown).

In this way, the analog signal output of the image information read by the contact image sensor 3 is transmitted to the signal processing unit 6 using a laser beam, so that reading by the contact image sensor 3 can be performed at high speed and with high resolution. However, since the number of signal cables does not increase as in the past, the space required for signal transmission is reduced and the device can be made smaller.

In addition, signal transmission using laser light tends to induce the noise that occurs when signal transmission is performed using signal cables, and the characteristics of the rising and falling portions of analog signals deteriorate.
Problems such as wire breakage accidents due to peeling of the insulation no longer occur.

FIG. 3 is an explanatory diagram showing the power supply to the contact type image sensor of the present invention. Power is supplied to the image reading section 12 from the power supply section 7 through the power supply cable 10 as in the conventional case.

[Effects of the Invention] As described in detail above, according to the present invention, the analog signal output of the image information read by the contact type image sensor is sent to the signal processing section, and the A/D is used in addition to the contact type image sensor.
Since signals are transmitted using laser light between the image reading unit having a converter and laser emitting element, the mirror, and the laser receiving element, the space required for signal transmission is reduced, making the device more compact and reducing noise. This has the effect of eliminating characteristic deterioration in the rising and falling portions of the analog signal, and eliminating disconnection accidents caused by peeling of the coating.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing an embodiment of the present invention, FIG. 2 is a block diagram schematically showing a conventional image reading device, and FIG. 3 is an explanation showing power supply to the contact type image sensor of the present invention. It is a diagram. 3...Contact image sensor, 4...Document, 6...
- Signal processing unit, 10... A/D converter, 11... Laser emitting element, 12... Image reading unit, 13.14...
-Mirror, 15...Laser light receiving element. Diagram

Claims (1)

[Claims] In an image reading device that reads a document by scanning the document placed on a platen glass with a contact image sensor, there is provided a contact image sensor that optically reads the document, and a contact image sensor that reads the document optically. An A/D converter that converts the analog signal output of image information read by the sensor into a digital signal;
It has a laser light emitting element that emits the digital signal output by the D converter as a pulse wave of laser light, and an image reading section that scans the document in the sub-scanning direction, and converts the path of the laser light emitted from the laser light emitting element. a laser light receiving element for receiving the laser light whose path has been changed by the mirror and converting the pulse wave of the laser light into a digital signal; and a laser light receiving element for transmitting the digital signal output from the laser light receiving element to an external circuit. An image reading device comprising: a signal processing section having the functions of: