JPS60230276A - Picture reader - Google Patents

Abstract

PURPOSE:To obtain securely a picture signal corresponding to a recorded picture recorded on a blank form by carrying out the correction processing, which removes a picture signal corresponding to a black plate from a blank form picture signal. CONSTITUTION:A black plate is disposed at a prescribed position on a white sheet base beforehand, and base picture signals including the black plate are stored in a memory 14. Then photoelectric conversion part 10 converts pictures recorded on a blank form into electrical signals, which are outputted as address signals to a ROM13 through an amplifier 11 and an A/D convertor 12. The ROM13 stores a table for a correcting picture signals beforehand, and outputs correction picture signals based on base picture signals outputted from the memory 14 and picture signals outputted from the A/D convertor 12. After these correction picture signals are binary-coded by a comparator 15, they are stored in a memory 16.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image reading device used, for example, in an optical reading device.

[Technical background of the invention and its problem] Conventionally, in an optical reading device, etc., a sheet of paper to be read is conveyed to a predetermined reading position, and at this reading position, the sheet is scanned by a photoelectric conversion unit to convert the sheet into a sheet. An image reading device is provided that converts images such as recorded characters into electrical signals. In this image reading device, a sheet of paper set at a reading position is usually held by a black sheet base. If the sheet base is black, there is a problem that when a thin sheet of paper is scanned by the photoelectric conversion section, the black color of the sheet base is detected as an image by the photoelectric conversion section.

In order to solve these problems, it is conceivable to use a white sheet base. However, if the sheet base is white, shadows may occur at both ends of the paper within the scanning area of the photoelectric conversion unit, and these shadows may be read as images.

Such shadows are thought to be caused by the position of the light source of the photoelectric conversion unit, the lifting of the paper from the sheet base, or the like.

[Object of the Invention] The present invention has been made in view of the above points, and its object is to prevent shadows from forming on both ends of the paper in an image reading device that uses a white sheet base for holding the paper at the reading position. An object of the present invention is to provide an image reading device that can reliably read only an image recorded on a sheet of paper even when such an image occurs.

[Summary of the Invention] The present invention is provided with an image signal correction unit that scans a sheet of paper held by a white sheet base with a photoelectric conversion unit and corrects an image signal output from the photoelectric conversion unit.

This image signal correction means has a function of removing image signals corresponding to shadows occurring at both ends of the paper and extracting only image signals corresponding to the images recorded on the paper.

That is, in the present invention, a white sheet base is provided that holds a sheet of paper to be read at a predetermined reading position.

Further, a sheet guide plate is provided that guides the paper with black plates that move according to the width of the paper on the sheet base and contact both ends of the paper. The photoelectric conversion means generates a paper image signal obtained by photoelectrically converting the image recorded on the paper on the sheet base. The memory means temporarily stores the sheet-based image signal output from the photoelectric conversion in a state where the paper is not present at the reading position. The image signal correction means generates an image signal corresponding to the recorded image on the paper from the paper image signal based on the paper image signal output from the photoelectric conversion means and the sheet base image signal output from the memory means. It is configured to generate a corrected image signal from which image signals other than the above are removed.

As a result, the image signal correction means always outputs only the image signal corresponding to the image recorded on the paper.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a block diagram showing the configuration of an image reading device according to an embodiment. In FIG. 1, a photoelectric conversion unit 10 optically scans a sheet of paper at a predetermined reading position and converts an image I recorded on the sheet into an electrical signal. Photoelectric conversion section 10
The electrical signal outputted from the amplifier 11 is amplified by an amplifier 11 and then given to an A/D converter 12 . This A/D converter 12 converts the electrical signal output from the amplifier 11 into a digital signal and outputs it as an address signal for a ROM (read only memory) 13. Further, the A/D converter 12 converts an electric signal given when there is no paper at the reading position into a digital signal and outputs the digital signal to the memory 14 . This memory 14 outputs the stored digital signal (hereinafter referred to as base image signal BI) as an address signal for the RC'M13.

The ROM 13 stores a corrected image signal table in advance,
Based on the image signal output from the A/D converter 12 (hereinafter referred to as paper image signal P) and the base image signal output from the memory 14, a corrected image signal CZ is output from the table. The comparator 15 converts the corrected image signal CI output from the ROM 13 into a binary signal based on a preset slice level signal SL, and outputs the binary signal. The binarized signal output from the comparator 15 is stored in the memory 16. The X-direction address counter 17 generates address signals necessary for the operation of the photoelectric conversion section 10 and memories 14 and 16.

Next, FIGS. 2(a) and 2(b) are diagrams showing the peripheral mechanism of the photoelectric conversion unit 10 of the image reading device, respectively, with FIG. 2(a) being a plan view and FIG. 2(b) being a side view. .

In FIG. 2, a hopper 20 is a holding section that holds a sheet 21 to be fed to a reading position. Paper 21 on hopper 20
is conveyed to the reading position by the drive of the feed belt 22 that constitutes the conveyance mechanism. The paper 21 is conveyed while being guided at both ends by a sheet guide 23 that is movable left and right according to the width of the paper 21. At the reading position, the same figure (b)
As shown in FIG. 2, a light source 24 and a photoelectric conversion element (made of COD or the like) 25 that constitute the photoelectric conversion section 10° are provided. The paper 21 conveyed to the reading position is held by a sheet base 2G having a white surface. Furthermore, both ends of the paper 21 at the reading position are guided by sheet guide levers 27. This seat guide lever 27 is attached to the seat guide 23 and includes black plates 28 of a constant width arranged at both ends of the seat 21 on the seat base 26. This black plate 28 is attached to the sheet guide lever 27 so as to hold the paper 21 at both ends. In addition, in the same figure (b), 2
9 is light! This is a mirror that transmits light generated from the paper 24 and reflected from the paper 21 to the photoelectric conversion element 25.

The operation of an embodiment of the image reading apparatus configured as described above will be described. First, when the paper 21 is set in the hopper 20, the sheet guide 23 is adjusted according to the width of the paper 21. The paper 21 on the hopper 20 is conveyed in the direction of the reading position (arrow 30) by the drive of the feed belt 22. At this time, the sheet guide lever 27 is also set at a position corresponding to the width of the paper 21. As a result, the paper 21 is moved to the sheet guide 23 and the sheet guide lever 27.
The sheet is conveyed to a reading position on the white sheet base 26 while being guided by the sheet.

By the way, before the paper 21 is conveyed to the reading position as described above, the photoelectric conversion section 10 scans the range X as shown in FIG. 2(a). An electrical signal resulting from this scanning is output to the amplifier 11.

This amplifier 11 outputs a white sheet base 26 and a black plate 2 when there is no paper 21 at the reading position.
An image signal corresponding to No. 8 is output in a waveform as shown in FIG. 3(C). In this amplifier output waveform, the black level is set to O■, and the white level is set to minus (-).

The output signal of the amplifier 11 is converted into a digital signal by the A/D converter 12 and then stored in the memory 14 as a base image signal B corresponding to the seat base 26. That is,
In this state, since there is no paper 21 on the sheet base 2G, the base image signal B is a white level signal containing only a black level signal corresponding to the black plate 28.

Note that the base image signal B in the absence of the black plate 28 becomes a digital signal with a white level corresponding to the waveform shown in FIG.

Next, assume that the paper 21 is conveyed to the reading position as shown in FIG. 2(a) as described above. That is, a predetermined portion of the sheet 21 is held on the sheet base 26, and both ends thereof are held by the black plate 28 of the sheet guide lever 27. In this state, the range
An electrical signal scanned by the photoelectric converter 10 and output from the photoelectric converter 10 is given to the amplifier 11 . In this case, photoelectric conversion section 1
If no image is recorded in the portion v521 scanned with 0, the output waveform of the amplifier 11 will be as shown in FIG. 3(C).

That is, an image signal having a black level signal 31 corresponding to 28 is outputted from the amplifier 11 to the black plates 1 disposed at both ends of the paper 21 . Further, if a predetermined image is recorded on the paper 21, the amplifier 11 outputs an image signal including a black level recorded image signal 32 as shown in (1) in the same figure. Assume that the amplifier output signal shown in (d) is converted into a digital signal by the A/0 converter 12 and output as a paper image signal PI.

This paper image signal PI is supplied to the ROM 13 as an address signal for the ROM 13 without being written into the memory 14. The output of such A/D converter 12 is stored in memory 1.
The sub-part of determining whether or not to transfer the image to No. 4 is performed by a control device (not shown) of the image reading device.

The base image signal B is supplied to the ROM 13 as an address signal from the memory 14 together with the paper image signal P. The ROM 13 stores the corrected image signal table in advance as described above, and generates the corrected image signal C corresponding to the address signal. This corrected image signal table is designed to create a corrected image signal C (an image signal with the output waveform of the amplifier 11 as shown in FIG. 2(e)) by removing the base image signal B from the paper image signal PI. It is a configured table. At this time, if no image is recorded on the paper 21, the corrected image signal C is an output waveform of the amplifier 11 and becomes an image signal with a white level as shown in FIG. Then, the corrected image signal C output from the ROM 13 is converted into a binary signal by the comparator 15, and the memory 1
6. A binary image signal is sent from this memory 16 to, for example, a character recognition section of an optical character reading device.

In this way, the black plate 28 is placed in advance at a predetermined position on the white sheet base 26, and the base image signal B including this black plate 28 is stored in the memory 14. Based on this base image signal B, the paper image signal P obtained after the paper is set at the reading position is corrected. The corrected image signal C obtained by this correction is an image signal obtained by removing the black level image signal corresponding to the black plate 28 from the paper image signal PI. Therefore, conventionally, image signals 33 corresponding to the shadows at both ends of the paper as shown in FIG. 3(b) are included in the image signal 31 corresponding to the black plate 28 of the base image signal B process.

Since a correction process is performed to remove the image signal 31 corresponding to the black plate 28 from the paper image signal P, it is possible to reliably obtain only the image signal corresponding to the recorded image recorded on the paper. It will be possible.

[Effects of the Invention] As detailed above, according to the present invention, in an image reading device using a white sheet base, unnecessary image signals generated corresponding to both ends of the paper are removed from the paper image signal PI. can be removed. Therefore, only the image signal corresponding to the image recorded on the paper can be obtained reliably at all times, and highly accurate image reading processing can be executed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the circuit configuration of an image reading device according to an embodiment of the present invention, and FIG. 2(a) is a block diagram showing the circuit configuration of an image reading device according to an embodiment of the present invention. (b) is a diagram showing the structure of the peripheral mechanism of the photoelectric conversion section in FIG. 1, and FIG. 3(a) is a plan view, FIG. 3(b) is a side view, and FIGS. 3(a) to (e). 2 are amplifier output waveform diagrams for explaining the operation of the image reading device shown in FIG. 1, respectively. 10... Photoelectric conversion unit, 11... Amplifier, 13...
ROM, 14°16...Memory, 21...Paper, 2
3... Seat guide, 26... Seat base, 21
... Seat guide lever, 28... Black plate. Figure 1b / Figure 2 (a) (b) Figure 3

Claims (1)

[Claims] A white sheet base that holds the paper to be read at a predetermined reading position, and a black sheet guide that moves according to the width of the paper on this sheet base and contacts both ends of the paper to guide the paper. a plate, a photoelectric conversion means for generating a paper image signal obtained by photoelectrically converting an image recorded on the paper on the sheet base, and output from the charging conversion when the paper is not present at the reading position. memory means for temporarily storing the sheet-based image signal;
Correction in which image signals other than the image signals corresponding to the recorded image on the paper are removed from the paper image signal based on the paper image signal output from the photoelectric conversion means and the sheet base image signal output from the memory means. An image reading device comprising: an image signal correction means for outputting an image signal.