JP2002218179A - Image reader, image read system, image forming system and image read method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image reader that can automatically adjust a regist offset and to provide an image read system, an image forming system and an image read method. SOLUTION: A line image sensor (CCD) 209 sequentially reads a line image of an original. An original carrier roller 75 is colored with density in compliance with a prescribed density standard and when the background color of the original 40 is white in most cases, stored electric charges in each pixel of the CCD209 are suddenly changed at an edge of the original in the main scanning direction. Then the edge at the tip of original in the main scanning direction is detected on the basis of the suddenly changed part of the solid-state image pickup device of the CCD209 and the detected edge part is used for a main scanning synchronizing signal HSYNC after the update. By forming the image on the basis of the main scanning synchronizing signal HSYNC after the update, a resist offset for each original can be automatically adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus, an image reading system, an image forming system, and an image reading method, and particularly to registration adjustment.

[0002]

2. Description of the Related Art Conventionally, when reading a double-sided original, an AD
A document reversing mechanism is provided inside F. First, the surface of the document is read by the image reading device side, and after reading is completed, the document is reversed by the document reversing mechanism inside the ADF, and the image reading device side reads the back surface of the document. The original image was being read.

However, in this configuration, the time for reversing the original becomes a dead time of the reading device, which deteriorates the reading performance and often causes damage to the original for reversing the original.

In view of this problem, a one-pass double-sided image reading apparatus has recently been proposed which is equipped with a reading system inside the ADF and reads a front side image and a back side image by one document feeding operation.

The reading operation of the one-pass double-sided image reading apparatus will be described. FIG. 5 is a diagram showing a schematic configuration of a one-pass double-sided reading device. A plurality of double-sided originals placed on the original placing table 71 of the ADF 70 are transported one by one. Documents are separated and conveyed one by one by separation rollers 72 and 73 in the conveyance path, and the documents are conveyed along conveyance guides 74 and 77 as the conveyance roller 75 rotates in the arrow direction.

By the time the document is conveyed to the reading position, the reading section 200 moves directly below the shading correction plate 211 and performs shading correction. When the shading correction is completed, the reading unit 200 moves to a position immediately below the drift reading window 212, and stands by for reading until a document is conveyed.

When the document is conveyed, the front surface image of the document is read immediately below the conveyance roller 75. That is, the line image of the document image illuminated by the lamp 201 in the image reading device 200 is divided into the first mirror 205 and the second mirror 20.
6, CCD 2 via third mirror 207 and lens 208
The image is formed at 09 and the line image is read.

The transport roller 75 transports the document at a predetermined speed, sequentially reads the document in the sub-scanning direction, and reads the front surface image of the document. As the reading of the front side document image progresses, and when the edge of the document is conveyed immediately below the same size reading box 250, the image on the back side of the document is read by the same size reading box 250. The optical system of the equal-magnification reading box 250 includes a SELFOC lens 251, a contact sensor 252, and a lamp 253. The line image of the back side image of the document illuminated by the lamp 253 is transmitted through the SELFOC lens 251 to the contact sensor 252. Image on top. Contact sensor 252
The line image formed on the image is a 1: 1 image. Since the transport roller 75 transports the document at a predetermined speed,
Reading of the document in the sub-scanning direction is sequentially performed, and reading of the back side image of the document is performed. The double-sided originals for which reading has been completed are sequentially discharged to the discharge tray unit 78.

The image data of the front surface and the back surface thus read are sent to an image processing circuit (not shown), and are sent to a host computer or a printer connected to the image reading device via an appropriate interface. Is reproduced, and an image forming process is performed so as to form an image on a display or print paper.

On the other hand, when reading a book type original such as a spread book, the ADF 70 is opened, the original is placed on the original glass, and the reading unit 200 and the second mirror 206 are read.
The third mirror 207 is scanned rightward in FIG. 5 to read the image of the document.

In such a reading apparatus, registration adjustment of the read image is required. In other words, the assembly of the optical system has some variation in assembly accuracy,
For example, among all the pixels of the CCD 209 in FIG. 5, it must be adjusted for each machine from which pixel is the reading start position of the original image. If the adjustment is not appropriate, the image is shifted, causing unnecessary margins or missing the image.

This registration adjustment must of course be performed in the 1: 1 reading box 250 as well. For example, as described in Japanese Patent Application Laid-Open No. 2000-151910, the registration adjustment is performed by reading a black line in a specific chart using a specific chart and performing registration adjustment according to read position information of the read black line. Has been proposed.

Japanese Patent Application Laid-Open No. Hei 5-328052 describes a method of performing registration adjustment in both the platen mode 1 and the ADF mode 2 using a black original. The platen mode 1 is the reading unit 20 in the example of FIG.
The ADF mode 2 corresponds to the registration adjustment of the reading system read by the equal-magnification reading box 250.

[0014]

However, the ADF
The document placing table 71 in FIG. 70 is as shown in FIG. 6 (FIG. 6 is a view of the ADF 70 viewed from directly above), and the document is placed so as to be sandwiched by the document guide 31. The document guide 31 is operable in the direction of the arrow,
A sensor (not shown) generates a signal in conjunction with the operation of the document guide 31, and the ADF 70 can detect which size document is placed on the document placing table 71. AD
The F70 and the image reading device 200 are connected by an interface (not shown), and the status of each other can be known by a communication protocol provided in the interface. Therefore, the image reading device 200 also has a document placed on the document placing table 71. You can know the size of the.

The registration of the ADF 70 and the image reading apparatus 200 has been adjusted in advance, and the approximate registration has been adjusted. However, at present, the document width set by the document guide 31 is smaller than the actual document width. Is set somewhat wide so that the document can be transported smoothly.
Also, even if the original to be placed is, for example, uniform A4 size, there are many cases where the dimensions are slightly different.
Therefore, there is a problem that the registration shifts for each document even if the registration adjustment is performed.

The present invention has been made under such circumstances, and provides an image reading apparatus, an image reading system, and an image reading method capable of automatically adjusting a registration error for each document. It is the purpose.

[0017]

In order to achieve the above object, according to the present invention, each time an original is read, the position of the original to be read is detected and the registration information is updated, and the setting of the original guide on the original placing table and the like are performed. In this case, the image shift due to a slight difference in the document size is canceled.

More specifically, the image forming apparatus is configured as in the following (1) to (3), the image reading system is configured as in the following (4) to (6), and the image forming system is as follows. The configuration is as described in (7) and (8), and the image reading method is configured as in (9) below.

(1) An image reading apparatus comprising a first line image sensor for reading a line image of a document and outputting a first main scanning synchronization signal synchronized with the line image together with information on the line image. First edge detecting means for detecting an edge portion of the document in the main scanning direction for each document by a line image sensor, and the first main scanning synchronizing signal in accordance with the edge information detected by the first edge detecting means. An image reading apparatus comprising: first timing changing means for changing output timing.

(2) In the image reading device described in (1), the first edge detecting means detects an edge portion in the main scanning direction at a leading end of the document.

(3) In the image reading device according to the above (1) or (2), when the edge cannot be detected by the first edge detecting means, the first timing changing means makes the first timing change means. An image reading apparatus that does not update the output timing of the main scanning synchronization signal.

(4) An automatic document feeder for automatically feeding documents one by one to the image reading apparatus according to any one of the above (1) to (3) and sequentially transporting the documents to a predetermined reading position. Wherein the auto document feeder includes a second line image sensor that reads a line image of the document, and an edge portion in the main scanning direction of the document for each document by the second line image sensor. A second edge detecting means for detecting, and a second timing changing means for changing the output timing of the second main scanning synchronization signal according to the edge information detected by the second edge detecting means,
An image reading system that outputs a second main scanning synchronization signal synchronized with the line image together with the line image information.

(5) In the image reading system described in (4), the second edge detecting means detects an edge portion in the main scanning direction at the leading end of the document.

(6) In the image reading system according to the above (4) or (5), if the edge cannot be detected by the second edge detecting means, the second timing changing means executes the second timing changing means. Image reading and reading system which does not update the output timing of the main scanning synchronization signal of the image reading and reading system.

(7) An image forming system comprising: the image reading device according to any one of (1) to (3); and an external device such as a host computer and a printer connected thereto. The information of the line image generated by the image reading device and the updated first main scanning synchronization signal are supplied to the external device, and the external device converts the image based on the updated first main scanning synchronization signal. Image forming system to form.

(8) An image forming system comprising: the image reading system according to any one of (4) to (6); and an external device such as a host computer and a printer connected thereto. The line image information generated by the image reading device and the updated first main scanning synchronization signal and the line image information generated by the auto document feeder and the updated second main scanning synchronization signal are supplied to the external device. And an image forming system for forming the front and back images of the document based on the updated first main scanning synchronization signal and second main scanning synchronization signal in the external device.

(9) A reading step of reading a line image of a document by a line image sensor, an edge detecting step of detecting an edge portion of the document in the main scanning direction for each document based on a signal read in the reading step, A timing change step of changing the output timing of the main scanning synchronization signal according to the edge information detected by the edge detection step; and information on the line image read in the reading step and the main scanning synchronization signal updated in the timing change step. And an output step of outputting.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples of an image forming apparatus. The present invention is not limited to the form of the device, but is supported by the description of the embodiment,
Can also be implemented in the form of a method

[0029]

(Embodiment 1) FIG. 1 is a diagram showing a main configuration of an "image forming apparatus" according to Embodiment 1. In FIG. This figure is an enlarged view of the arrangement of members around the document conveying roller 75 in FIG. The same reference numerals as in FIG. 5 denote the same members in FIG. Reference numeral 40 denotes a document, and the document feeding state in FIG.
(CCD 209 in FIG. 5) shows a state of being read.

The original conveying roller 75 is colored at a density according to a predetermined density standard. Since the ground color of the document 40 is mostly white, the state of reading by a CCD (not shown) is as shown in FIG. FIG. 2 shows the original 40 and the CCD 209.
And the type of read data of each pixel of the CCD. A pixel represented by black indicates black read data, and a pixel represented by white indicates white read data. As can be seen from the reading state of the CCD 209 in FIG. 2, it can be easily detected that the edge of the document is at the position of the pixel A by image data processing such as general edge enhancement.

As described above, when the edge of the original 40 in the main scanning direction is detected according to the state of reading the leading end of the original by the CCD 209, the main scanning synchronization signal HSYNC is output as shown in FIG.
The output timing of the image data is changed and output together with the read image data to an external device such as a host computer or a printer connected to the image reading device.

The external device which has received the main scanning synchronization signal HSYNC and the image data recognizes the subsequent image data as valid image data at the rising timing of the HSYNC, and reproduces an image in accordance with the valid image data.

This registration adjustment is also performed in the same size reading box 250. That is, the contact sensor 2
52, the reading state of the leading edge of the document is checked, and the image data of the contact sensor 252 and the adjusted HSY
The NC signal is sent to the external device as back side document image data.

When the reading of the original has been completed and the second original has been fed and the state of reading the leading end of the original is as shown in FIG. 4, the timing is adjusted to the pixel A as shown in FIG. The timing of the scan synchronization signal HSYNC is adjusted to the pixel B and sent to the external device.

The meaning of FIG. 4 is that although a document of the same size is fed, there is a shift between the pixels A and B at the reading position of the reading system.
Image data without image shift is always transmitted to an external device.

As described above, according to this embodiment,
When a continuous document is read by the ADF, the registration deviation of each document is automatically adjusted, so that an image without any missing image can be provided for each document.

(Embodiment 2) In the above description of the operation of the embodiment 1, if the background color of the document is a color close to the density of the conveying roller 75 or if an image exists up to the edge of the document, Sometimes the edges of the document cannot be detected. At this time, control is performed so that the output timing of the main scanning synchronization signal HSYNC is not updated, but is output at the timing of the previously updated main scanning synchronization signal HSYNC. Therefore, although accurate registration adjustment is not performed, it can be said that extreme registration deviation rarely occurs because the rough adjustment is performed.

In each of the embodiments described above, the edge of the original in the main scanning direction is detected at the leading end of the original and the main scanning synchronization signal is updated. However, the present invention is not limited to this. At the edge of the document in the main scanning direction,
This can be implemented by updating the main scanning synchronization signal to the leading end of the document.

[0039]

As described above, according to the present invention,
At the time of reading a document, the registration deviation for each document is automatically adjusted, so that an image without image defects can be provided for each document.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a main part of a first embodiment.

FIG. 2 is a diagram showing a relative position between a document and a CCD and a reading state of the CCD.

FIG. 3 is a diagram showing a CCD reading state and HSYNC timing.

FIG. 4 is a diagram showing an example of updating the timing of HSYNC.

FIG. 5 is a diagram showing a configuration of a conventional example.

FIG. 6 is a plan view of the document table.

[Explanation of symbols]

 40 manuscript 70 ADF 209 CCD 250 1: 1 reading box

Claims (9)

[Claims] 1. An image reading apparatus comprising: a first line image sensor for reading a line image of a document; and outputting a first main scanning synchronization signal synchronized with the line image together with the line image information. First edge detecting means for detecting an edge portion of the document in the main scanning direction for each document by the image sensor; and outputting the first main scanning synchronization signal in accordance with the edge information detected by the first edge detecting means. An image reading apparatus comprising: a first timing changing unit that changes a timing. 2. The image reading apparatus according to claim 1, wherein
The image reading apparatus according to claim 1, wherein the first edge detecting means detects an edge portion in a main scanning direction at a leading end of the document. 3. An image reading apparatus according to claim 1, wherein when the first edge detecting means fails to detect an edge, the first timing changing means causes the first main scanning synchronizing signal to be outputted. An image reading apparatus that does not update the output timing of the image reading apparatus. 4. An image reading apparatus according to claim 1, further comprising an automatic document feeder for automatically feeding the originals one by one and sequentially transporting the originals to a predetermined reading position. A reading system, wherein the automatic document feeder includes a second line image sensor that reads a line image of the document, and a second line image sensor that detects an edge portion in the main scanning direction of the document for each document by the second line image sensor. Edge detecting means, and second timing changing means for changing the output timing of the second main scanning synchronization signal according to the edge information detected by the second edge detecting means. An image reading system for outputting a second main scanning synchronization signal synchronized with an image. 5. The image reading system according to claim 4, wherein said second edge detecting means detects an edge portion in a main scanning direction at a leading end of the document. 6. The image reading system according to claim 4, wherein when an edge cannot be detected by said second edge detecting means, said second main scanning synchronization is performed by said second timing changing means. An image reading and reading system, wherein the signal output timing is not updated. 7. An image reading apparatus according to claim 1, further comprising: a host computer connected to the image reading apparatus.
An image forming system comprising an external device such as a printer, wherein the image forming apparatus supplies information on a line image generated by the image reading device and an updated first main scanning synchronization signal to the external device. The image forming system according to claim 1, wherein the image is formed based on the updated first main scanning synchronization signal. 8. An image forming system comprising: the image reading system according to claim 4; and an external device connected to the image reading system, such as a host computer or a printer. The information of the generated line image and the updated first main scanning synchronization signal and the information of the line image generated by the auto document feeder and the updated second main scanning synchronization signal are supplied to the external device. An image forming system, wherein an external device forms front and rear images of a document based on the updated first main scanning synchronization signal and second main scanning synchronization signal. 9. A reading step for reading a line image of a document by a line image sensor, an edge detecting step for detecting an edge portion of the document in the main scanning direction for each document based on a signal read in the reading step, A timing change step of changing the output timing of the main scanning synchronization signal according to the edge information detected by the detection step; and outputting information of the line image read in the reading step and the main scanning synchronization signal updated in the timing change step. An image reading method.