JPH0622093A - Original reader - Google Patents

Abstract

PURPOSE:To miniaturize the device by detecting the head and width of an original with an image sensor for reading. CONSTITUTION:When an original 1 is not set at a read position, the surface of a platen roller 8 with optical images made incident on a bonding type image sensor 6 is formed with three black lines at the center and both of edges on a white base. At the timing corresponding to the positions of three black lines and white base near the respective black lines, it is judged whether the output signal of the image sensor 6 is white or black and the head and width (size) of the original can be detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading apparatus such as a facsimile or OCR, and more particularly to a mechanism for detecting the leading edge and width (size) of a document.

[0002]

2. Description of the Related Art A conventional document reading apparatus is shown in FIG.
It shows in (c). FIG. 4A is a sectional view of the reading unit in the main scanning direction. In FIG. 4A, the illumination light of the fluorescent lamp 4 is reflected by the original 1, and an optical image corresponding to the original 1 is made incident on a one-dimensional image sensor (hereinafter, CCD) 3 such as a charge coupled device by a lens 2.

FIG. 4B shows the CCD 3 when there is no original 1.
Surface part 2 of the paper guide 15 on which the optical image is incident
2 is shown, and the entire surface is white to be used as a reference for signal correction of the light amount of the fluorescent lamp 4, the shading of the lens 2, and the deviation (shading) of the sensitivity of the CCD 3 in the main scanning direction.

FIG. 4C shows the CC when the original 1 is not present.
The output signal 37 for one line of D3 is shown.

The document reading device is provided with a cam 9 and a photo interrupter 10 shown in FIG. 4A in order to detect the start and end of document reading in the sub-scanning direction. The cam 9, which was pressed in the direction a by a spring (not shown) when the document 1 was not present, rotates in the direction b at the tip of the document 1 and enters between the light emitting element and the light receiving element of the photo interrupter 10, and the photo interrupter. The leading edge of the document 1 is detected by the output signal of 10.

Further, since it is necessary to change the transmission signal according to the width (size) of the original in a facsimile or the like, the skew detection in the sub-scanning direction of the original and the interval between the inexpensive paper guides are detected by the switch. ing.

[0007]

However, in this conventional document reading apparatus, since the cam and the photo interrupter are arranged on the traveling path of the document to detect the leading edge of the document, the paper guide is about 15 mm in the sub-scanning direction. There is a problem that it becomes longer and the device becomes larger.

There is also a problem that a switch for detecting the width (size) of the document is required.

The present invention has been made in view of the above-mentioned conventional circumstances, and therefore an object of the present invention is to provide a novel original reading apparatus capable of solving the above-mentioned problems inherent in the conventional art. To do.

[0010]

In order to achieve the above object, a document reading apparatus according to the present invention deals with an optical image incident on the image sensor when the document is not placed at the reading position of the image sensor. The part inside the device is provided with a surface which is a single and a plurality of black lines in the sub-scanning direction on a white background, and the level of the output signal of the image sensor is the black line and the position of the white background in the vicinity thereof. And a means for determining white or black at a timing corresponding to.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will now be specifically described with reference to the drawings for each of its preferred embodiments.

FIGS. 1A to 1C are schematic views showing a first embodiment according to the present invention.

FIG. 1A is a sectional view of the reading unit in the main scanning direction. Compared to the conventional device of FIG. 4A, there is no cam and photo interrupter, and the length of the paper guide in the sub scanning direction is smaller than that of the conventional device. It is about 15 mm short.

FIG. 1B shows a CCD when there is no original 1.
3 shows the surface portion of the paper guide 5 on which the optical image is incident. This is different from the conventional device of FIG. 4B in that a black line 21 is located at the center in the main scanning direction.

FIG. 1C shows the CCD 3 when there is no original 1.
3 is a time chart of the output signal 31 for one line and the digital signal 32 showing the timing for determining the level of the output signal 31.

In the determination circuit not shown in FIG. 1A, the level of the output signal 31 of the CCD 3 is determined at the center of the main scanning effective period in which the digital signal 32 is level "1" and timings before and after that. To be done. If it is determined that the center of the effective period of the main scanning is black and the areas before and after it are white, the document is not at the reading position in the sub-scanning direction, and in other cases, the leading edge of the document is detected. It

As a reference for shading signal correction, the portion of the output signal 31 of the CCD 3 corresponding to the black line 21 is interpolated from the white background portions before and after.

2A to 2C are schematic diagrams showing a second embodiment according to the present invention.

FIG. 2A is a sectional view of the reading section in the main scanning direction, in which reading is performed by the contact image sensor 6.
The original 1 is brought into close contact with the contact image sensor 6 by the film 7.

FIG. 2B shows the surface portion of the film 7 on which the optical image is incident on the contact type image sensor 6 when the original 1 is not present, and black lines are arranged at regular intervals in the main scanning direction. There is.

FIG. 2C is a time chart of the output signal 33 for one line of the contact image sensor 6 when there is no original 1 and the digital signal 34 showing the timing for judging the level of the output signal 33. .

A determination circuit not shown in FIG. 2A determines the level of the output signal 33 of the contact image sensor 6 at the timing when the digital signal 34 is at the level "1".

If the judgment is different from the surface portion of the film 7 shown in FIG. 2B, it is detected as the leading edge of the original,
Further, the width (size) of the document is detected depending on at which timing in the main scanning direction different judgments are made.

FIGS. 3A to 3C are schematic views showing a third embodiment according to the present invention.

FIG. 3A is a cross-sectional view of the reading unit in the main scanning direction. Reading is performed by the contact image sensor 6,
The original 1 is brought into close contact with the contact-type image sensor 6 by the platen roller 8.

FIG. 3B shows a platen roller 8 on which an optical image is incident on the contact image sensor 6 when there is no original 1.
Shows the surface part of the main scanning direction, one center and A4
There are a total of three black lines, one at each end, at an interval of an intermediate value of about 234 mm between a size document width of 210 mm and a B4 size document width of 257 mm.

FIG. 3C is a time chart of the output signal 35 of one line of the contact image sensor 6 when there is no original 1 and the digital signal 36 showing the timing for judging the level of the output signal 35. .

In a determination circuit not shown in FIG. 3A, the level of the output signal 35 of the contact image sensor 6 is determined at the timing when the digital signal 36 is at level "1". The leading edge of the document 1 is determined and detected by the level of the output signal 35 corresponding to the central black line in the main scanning direction and the left and right white backgrounds nearby. The width (size) of the document 1 is such that the level of the output signal 35 corresponding to the black lines at both ends and the white backgrounds on the left and right near each black line is the same as the output signal corresponding to the platen roller 8 shown in FIG. 3C. Is detected as A4 or smaller, and other than B4 or larger.

As a reference for shading signal correction, a portion corresponding to a black line is interpolated from neighboring left and right white background portions.

[0030]

As described above, according to the present invention,
Since the leading edge and the width (size) of the document are detected by the image sensor for reading and the determination circuit of the output signal of the image sensor, there is no need for a detection switch, and the size of the apparatus can be reduced.

[Brief description of drawings]

1A and 1B show a first embodiment according to the present invention, in which FIG. 1A is a schematic sectional view, FIG. 1B is a front view of a reading portion of a paper guide, and FIG. 1C is a time chart.

FIG. 2 shows a second embodiment according to the present invention, (a) is a schematic sectional view, (b) is a surface view of a film, and (c) is a time chart.

FIG. 3 shows a third embodiment according to the present invention, (a) is a schematic sectional view, (b) is a surface view of a platen roller, and (c) is a time chart.

FIG. 4 is a conventional document reading device, (a) is a sectional view, (b) is a front view of a reading portion of a paper guide,
(C) is a time chart.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Original document 2 ... Lens 3 ... CCD 4 ... Fluorescent lamp 5, 15 ... Paper guide 6 ... Contact image sensor 7 ... Film 8 ... Platen roller 9 ... Cam 10 ... Photo interrupter 31, 33, 35, 37 ... Image sensor Output signal waveforms 32, 34, 36 ... Digital signals indicating the timing of determining the level of the image sensor output signal

Claims (1)

[Claims] 1. A document reading apparatus comprising at least a one-dimensional image sensor, a drive circuit for the image sensor, and means for making an optical image of the document incident on the image sensor, wherein the document is read by the image sensor. A portion inside the device corresponding to the optical image that is incident on the image sensor when not placed in position, comprises a white substrate with a surface which is one or more black lines in the sub-scanning direction,
An original reading apparatus further comprising at least a unit for determining whether the level of the output signal of the image sensor is white or black at a timing corresponding to the position of the black line and the position of the white background in the vicinity thereof.