JPH09163090A - Image reading device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To perform a plurality of reading operations on the same original without bothering the user, and even when originals having different attributes are mixedly set on the original tray. It is an object of the present invention to provide an image reading device that does not require a user's advance setting. A transport roller 19 and a guide roller 20,
In the first reading mode, the transporting unit 21 transports the document 36 on the document tray 13 in the forward direction and guides it to the reading position. After the reading is completed, the document 36 is further transported in the forward direction and discharged to the paper discharge tray 14. Then, in the second reading mode, the document 36 is conveyed in the forward direction and guided to the reading position, and after the reading is completed, the document 36 is conveyed in the reverse direction and stored in the document storage section 35. In the third reading mode,
Document attribute determination is performed based on the read image data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device equipped with an automatic document feeder.

[0002]

2. Description of the Related Art In recent years, workstations, personal computers, and the like have been enhanced in function so that full-color image editing, character input by electronic filing, OCR (optical character reader), etc., can be processed at high speed. Along with this, flatbed type color scanners that can easily input images have become popular.
Further, in order to speed up and simplify image input, a color scanner is provided with an automatic document feeder (hereinafter referred to as an ADF).
Opportunity to install is increasing.

A conventional image reading apparatus will be described below with reference to the drawings. FIG. 16 is a schematic diagram of a conventional image reading apparatus. In FIG. 16, a document glass 2a on which the user manually sets a document without using the ADF is arranged on the upper surface of the image reading apparatus main body 1. In addition, on the upper surface of the image reading apparatus main body 1, A
A glass window 2b is arranged at the document reading position when the DF is used. A supporting member 4 having a bearing and the like is fixed inside a carriage 3 that scans and reads a document. The carriage 3 is supported by a shaft 5 via a support member 4, and its movement is restricted only in the sub-scanning direction.

A drive wire 6 for transmitting a drive force to the carriage 3 is connected to the carriage 3, and the drive wire 6 is engaged with a drive pulley 7 and a driven pool 8. The drive pulley 7 is connected to the drive motor 9 by a connecting shaft and a reduction mechanism (both not shown), and drives the carriage 3 by rotating the drive motor 9. The driven pulley 8 is biased by the biasing means 11 via the driven pulley support member 10 to apply tension to the drive wire 6.

The ADF unit 12 continuously conveys a document to a reading position. Documents are set on the document tray 13. Documents that have been read are stacked on the discharge tray 14.

FIG. 17 is an enlarged view of the ADF unit 12 in the conventional image reading apparatus. Next, in FIG.
The DF unit 12 will be described. The document detection sensor 15 detects the presence or absence of a document set on the document tray 13. The documents set on the document tray 13 are fed one by one by the paper feed roller 16 and the reverse roller 17. The transport roller 19 and the guide rollers 20 and 21 are arranged to face each other. The originals fed by the paper feed roller 16 and the reverse roller 17 are conveyed one by one to the glass window 2b through the conveyance passage by the conveyance roller 19 and the guide roller 20. The document edge detection sensor 18 detects the leading edge and the trailing edge of the document. The original document conveyed to the glass window 2b is conveyed by the conveying roller 19 and the guide roller 21, and is further discharged by the discharge roller 23.
Is discharged to The document discharge detection sensor 22 detects the leading edge and the trailing edge of the document conveyed to the discharge tray 14.

FIG. 18 is a schematic diagram of an optical system of a conventional image reading apparatus. In FIG. 18, a lamp 24 irradiates a document with light. The aperture 25 substantially specifies the document reading position. The reflection mirror 26 reflects the reflected light from the document. The imaging lens 28 receives the image of the light reflected by the reflection mirror 26 from the color image sensor 2
Image on 5. The color image sensor 27 converts optical information into an electric signal.

The operation of the image reading apparatus configured as described above will be described below.

When the power of the image reading device is turned on,
Carriage 3 is no matter where the initial position is
The home position p1 is restored. Further, a black and white level correction (shading correction) is performed electrically using a reference calibration plate (not shown) provided near the home position p1. After that, the carriage 3 is returned to the home position p1 again to enter the standby state.

First, the operation of reading a document without using the ADF unit 12 will be described. This is an operation in which the user places an original on the original glass 2a and reads the original.

After setting the reading resolution, reading range and the like from an external host (not shown), a manuscript reading command is issued, and no manuscript is set on the manuscript tray 13 of the ADF unit 12, Document detection sensor 15
If the document is not detected, the lamp 24 is turned on and the drive motor 9 of the image reading apparatus main body 1 is rotated to transmit the drive force to the carriage 3 via the drive pulley 7, the drive wire 6 and the driven pulley 8. 3 is moved in the direction d1 from an external host (not shown) at a speed corresponding to a predetermined reading resolution. When the carriage 3 reaches the head of the area corresponding to the reading range set by an external host (not shown), the reading of the original placed on the original glass 2a is started. The original is illuminated by the lamp 24 through the original glass 2a. The reflected light from the document is reflected by the reflection mirror 26, is imaged on the color image sensor 27 by the imaging lens 28, and is converted into an electric signal. When the reading is completed in the designated reading range, the carriage 3 is then moved in the direction opposite to the direction d1 to return to the home position p1.

Next, the operation of reading a document using the ADF unit 12 will be described.

After setting the reading resolution, reading range and the like from an external host (not shown), an original reading command is issued, and the original is set on the original tray 13 of the ADF unit 12 to detect the original detection sensor. When 15 detects a document, the drive motor 9 of the image reading apparatus main body 1 is rotated, the drive force is transmitted to the carriage 3 via the drive pulley 7, the drive wire 6 and the driven pool 8, and the aperture 25 of the carriage 3 is made of glass. The position of the carriage 3 is controlled so as to be a predetermined position directly below the window 2b.
In this conventional example, the position of the carriage 3 is fixed, and a document is conveyed by the ADF to read an image.

Further, while turning on the lamp 24,
A drive motor (not shown) independently provided in the ADF unit 12 is rotated. The transport roller 19 is coupled to an ADF drive motor (not shown) via a speed reduction mechanism (not shown), and the transport roller 19 and the guide roller 20 facing the transport roller 19 are rotated together with the rotation of the ADF drive motor (not shown). , 21 starts rotating. When the rotation of the ADF drive motor (not shown) reaches a certain speed, the clutch mechanism (not shown) is controlled to rotate the paper feed roller 16 and the reverse roller 17 to convey the document set on the document tray 13. To start. The reverse roller 16 suppresses so-called double feeding, in which a plurality of documents are simultaneously conveyed, by utilizing the difference in friction between the roller and the document surface.

When the leading edge of the conveyed document is detected by the document edge detecting sensor 18, a clutch mechanism (not shown) is controlled to feed the paper feed roller 16 and the reverse roller 1.
The drive transmission to 7 is stopped. At this point, the document is reliably sandwiched between the transport roller 19 and the guide roller 20 facing the transport roller 19, and subsequent document transport is performed by the transport roller 19, and the paper feed roller 16 acts as a tension roller.

Further, at the time when the leading edge of the document is detected by the document edge detection sensor 18, the document is conveyed at a constant speed, and therefore the output of the document edge detection sensor 18 is used to start the image reading timing. Can be generated.

The transported original is illuminated by the lamp 24 through the glass window 2b, the reflected light from the original is reflected by the reflection mirror 26, and is imaged on the color image sensor 27 by the imaging lens 28 to generate an electrical signal. Is converted to.

When the image reading within the reading range designated by the external host (not shown) is completed, the original is conveyed as it is at the speed at which the original was read, and the leading edge of the original is conveyed to the conveying roller 19 and the roller. It is sandwiched between the guide roller 21 and the discharge roller 23.
As a result, the original is discharged to the discharge tray 14.

On the other hand, the trailing edge of the document is the document edge detection sensor 1
8 and when the document detection sensor 15 detects a document, the clutch mechanism (not shown) is controlled again to rotate the paper feed roller 16 and the reverse roller 17,
The conveyance of the document set on the document tray 13 is started.

By repeating the above operation, the originals stacked on the original tray 13 are sequentially conveyed onto the glass window 2b and the image is read.

The ADF described in the conventional example is applied to, for example, a filing device, an OCR, etc., and a document after scanning is discharged because it is unnecessary. For document transportation,
It is always done in the same direction and at the same speed.

[0022]

However, the conventional image reading apparatus described below has the following problems.

It is possible to edit a color image even at an individual level by connecting an image reading device and a personal computer. Recently, a document is once pre-scanned (all pixels are roughly read), and then a pre-scan is performed. There are increasing usages in which an area is designated according to image information obtained by scanning, a plurality of different areas of the same document are rescanned, or the same area is scanned a plurality of times by changing resolution parameters.

In the conventional image reading apparatus equipped with the ADF, the document fed by using the ADF is once discharged and then immediately ejected, so that it is not possible to cope with the above-mentioned work involving prescan. . If the user intends to use the ADF for these operations, the discharged document must be set again on the document tray every time the reading operation is performed, and there is a problem that the use efficiency is significantly reduced.

Generally, in image reading involving pre-scan, the original is manually placed on the original glass,
There is no choice but to read the original by moving the carriage in the sub-scanning direction. However, for example, when there are many originals to be processed, the user must rearrange the originals one by one on the original glass, and there is a problem that the advantage of mounting the ADF is lost.

Further, there are the following problems regarding the convenience of filing and the like. Recently, in filing work, there are increasing opportunities to handle mixed color / monochrome originals for each original.

Generally, reading a color original requires more time than reading in a monochrome, and the amount of data also increases significantly. If a document original (binary image) is read as a color original (multivalued image), the reading time will increase and the data amount will be 24 times (3 RGB colors * 8 bits). There is a lot of waste. Therefore, the user presets the attributes of the original document, that is, one of the color original document (multivalued image), the monochrome original document (multivalued image), and the monochrome original document (binary image) according to the purpose of use.

However, when a document originally having a plurality of attributes is mixed in a document that should be continuously read using the ADF, the user frequently resets the document attributes and executes image reading. Therefore, there is a problem that work efficiency is significantly reduced.

According to the present invention, the same original can be read a plurality of times without bothering the user, and even if originals having different attributes are mixedly set on the original tray, the user can read the same. It is an object of the present invention to provide an image reading device that does not require advance setting.

[0030]

An image reading apparatus according to the present invention comprises a document tray on which a document is placed, a reading unit for reading the document, and a conveying unit for conveying the document in the forward and reverse directions. It is a thing. In the first reading mode, the conveying unit conveys the document on the document tray in the forward direction and guides it to the reading unit, further conveys the document in the forward direction after the reading by the reading unit is completed, and discharges the document. At times, the document is conveyed in the forward direction and guided to the reading unit, and after the reading by the reading unit is completed, the document is conveyed in the reverse direction.

In the image reading apparatus according to the present invention, in the first reading mode, the document on the document tray is conveyed in the forward direction and guided to the reading unit, and the document is further read after the document is read by the reading unit. It is transported in the forward direction and discharged. On the other hand, in the second reading mode, the document is conveyed in the forward direction and guided to the reading unit,
After the document is read by the reading means, the document is conveyed in the reverse direction. As a result, the same document supplied from the document tray can be read multiple times. Therefore, it is possible to deal with a usage pattern in which the main scan is executed after the pre-scan.

Further, before the prescan operation, the original is conveyed from the original tray in the forward direction, the original is read by the reading means to determine the attribute of the original, and the original is conveyed in the reverse direction to be stored again in a readable position. It becomes possible. Therefore, even when documents having different attributes are mixedly set in the document tray during filing work, the user does not need to set the attributes of the documents.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION An image reading apparatus according to the first invention comprises a document tray on which a document is placed, a reading unit for reading the document, and a conveying unit for conveying the document in a forward direction and a reverse direction. The transport means transports the document in the forward direction and guides it to the reading means in the first reading mode, further transports the document in the forward direction after the reading by the reading means and discharges it, and in the second reading mode, Is conveyed in the forward direction to the reading means, and the document is conveyed in the reverse direction after the reading by the reading means is completed.

In this way, since the original read by the reading means can be conveyed in the opposite direction, the same original supplied from the original tray can be read a plurality of times. In addition, before the prescan operation, the document on the document tray can be transported in the forward direction, the document can be read by the reading unit to determine the attributes of the document, and the document can be transported in the reverse direction and stored again in a readable position. Becomes

An image reading apparatus according to a second aspect of the invention is the image reading apparatus according to the first aspect of the invention, in which the document is stored in the document storing means for storing a document and is conveyed in the opposite direction by the conveying means in the second reading mode. And a conveyance path switching means for guiding the original to the original storing means.

This makes it possible to smoothly store the original conveyed in the reverse direction in the second reading mode at a position where it can be read again.

An image reading apparatus according to a third aspect of the present invention is the image reading apparatus according to the second aspect of the invention, in which the conveyance path switching means does not hinder the conveyance of the original when the conveyance means conveys the document in the forward direction, The document transport direction is restricted when the document is transported in the opposite direction by the transport means.

As a result, the document can be smoothly conveyed in the forward direction, and the document can be reliably guided to the document storing means.

An image reading apparatus according to a fourth aspect of the present invention is the image reading apparatus according to the second or third aspect of the present invention, in which the conveyance path from the document tray to the reading unit and the conveyance path from the document storage unit to the reading unit. Has a common portion, and is further provided with a first document detecting unit arranged in the common portion and detecting a document.

This makes it possible to accurately control the conveyance of the document based on the output of the first document detecting means.

An image reading apparatus according to a fifth aspect of the present invention is the image reading apparatus according to the fourth aspect, wherein
Document detecting means detects the leading edge of the document conveyed in the forward direction by the conveying means in the first and second reading modes to generate the document reading start timing. When the document is stored in the storage means, the state of the document is output.

As a result, the reading of the original can be started accurately at a predetermined position, and the fact that the original is stored in the original storing means can be easily grasped.

An image reading apparatus according to a sixth aspect of the present invention is, in the configuration of the reading apparatus according to the fourth or fifth aspect, a reading start instructing means for instructing the start of reading an original, and the presence or absence of the original in the original tray. The apparatus further comprises a second document detecting means for detecting and a selecting means for selecting one of the originals of the original tray and the original storing means, and when the selecting means gives an instruction to start reading the original by the reading start instructing means. When both the first and second document detecting means detect the presence of a document, the document stored in the document storing means is selected, and the conveying means conveys the document selected by the selecting means to the reading means. Is.

As a result, the document stored in the document storing means can be read a plurality of times.

An image reading apparatus according to a seventh aspect of the present invention is the image reading apparatus according to the sixth aspect of the invention, wherein when the conveying means selects the original in the original storing means by the selecting means, the original is temporarily The document is conveyed in the reverse direction, and when the first document detecting unit detects the state of no document, the document is conveyed in the forward direction and guided to the reading unit.

As a result, the original stored in the original storing means can be read reliably.

An image reading apparatus according to an eighth aspect of the present invention is the image reading apparatus according to any one of the first to eighth aspects of the invention, in which a plurality of document guide members arranged near the reading unit and a document by the conveying unit are provided. The apparatus further includes a displacement unit that displaces the plurality of document guide members according to the transport direction.

As a result, the document can be smoothly conveyed to the reading means. An image reading apparatus according to a ninth aspect of the present invention is the image reading apparatus according to any one of the first to eighth aspects of the present invention, wherein designation means for designating a reading range and reading resolution for the original document and reading start for instructing the reading start of the original document are provided. Further comprising an indicating means,
When the reading start instructing means instructs the conveying means to start reading the original, the conveying means conveys the original at the maximum speed until the beginning of the reading range designated by the designating means reaches a predetermined position, and thereafter, the designating means. The original is conveyed at a speed that is set according to the reading resolution designated by.

As a result, the original can be guided to the reading means at high speed and the original can be read at a desired resolution.

An image reading apparatus according to the tenth invention is
In the configuration of the image reading device according to the first to eighth inventions, further, there is further provided a designating unit for designating a reading range for the document, and the transporting unit reads the reading range designated by the designating unit in the first reading mode. The document that has been completed is conveyed in the forward direction at the maximum speed and discharged.

As a result, the document read by the reading means can be discharged at high speed.

An image reading apparatus according to the eleventh invention is
In the configuration of the image reading device according to the first to eighth inventions, further, there is further provided a designating unit for designating a reading range of the original document, and the transporting unit, in the second reading mode,
The document whose reading range designated by the designation means has been read is conveyed in the reverse direction at the maximum speed.

Thus, the document read by the reading means can be stored at a position where it can be read again at high speed.

An image reading apparatus according to the twelfth invention is
In the configuration of the image reading apparatus according to the first to eighth inventions, in the third reading mode, the transporting unit transports the document on the document tray in the forward direction and guides it to the reading unit, and after the reading by the reading unit is completed, the document is read. Is further conveyed and stored in the document storing means in the reverse direction, and the determining means further determines the attribute of the document based on the output of the reading means in the third reading mode.

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus of FIG. 1 differs from the conventional image reading apparatus of FIG. 16 in that the configuration of the ADF unit 12 is different from the configuration of the ADF unit 12 of FIG. The configuration of the image reading apparatus main body 1 and the configuration of the optical system are the same as the configuration of the image reading apparatus main body 1 and the configuration of the optical system in the image reading apparatus in FIG. 16, and thus description thereof will be omitted.

FIG. 2 is an enlarged view of the ADF unit 12 of FIG. In FIG. 2, a document 36 is set on the document tray 13. The conveyance path switching unit 29 is arranged so as to be rotatable around the shaft 30, and switches the conveyance path of the document. The transport passage switching means 29 is biased in the direction d2 by its own weight when the document is not present in the transport passage. The first document guide member 31 and the second document guide member 32 are displaced around respective shafts 33 and 34 as rotation centers according to the document conveyance direction. The document storage section 35 is
The document conveyed in the reverse direction is temporarily stored. First
The stepped portion 37 and the second stepped portion 38 are located in front of and behind the glass window 2b, and become a factor that obstructs the conveyance depending on the conveyance direction of the document.

In this embodiment, the carrying roller 19 and the guide rollers 20, 21 constitute a carrying means, the carriage 3 constitutes a reading means, and the document storing section 35 constitutes a document storing means. Further, the document edge detection sensor 18 constitutes the first document detection means, and the document detection sensor 15 is the second document detection means.
Of the original document detecting means. Further, a control system (not shown) constitutes a selection means, and the first document guide member 31 and the second document guide member 32 constitute a plurality of document guide members. Further, the image data processing unit, which will be described later, constitutes the determining means.

The operation of the image reading apparatus configured as described above will be described below.

When the power of the image reading device is turned on,
Carriage 3 is no matter where the initial position is
The home position p1 is restored. Further, a black and white level correction (shading correction) is performed electrically using a reference calibration plate (not shown) provided near the home position p1. After that, the carriage 3 is returned to the home position p1 again, and enters the standby state. The operation of reading the document 36 without using the ADF unit 12 is the same as that of the conventional example, and thus the description thereof is omitted.

The operation of reading the original 36 using the ADF unit 12 will be described below.

First, the first reading mode in which the document 36 set on the document tray 13 is read and then discharged to the discharge tray 14 will be described.

After setting the reading resolution, reading range, etc. from an external host (not shown), an original reading command is issued, and the original 36 is set on the original tray 13 of the ADF unit 12 to detect the original. When the sensor 15 detects the document 36, the drive motor 9 of the image reading apparatus main body 1 is rotated, and the drive force is transmitted to the carriage 3 via the drive pulley 7, the drive wire 6 and the driven pulley 8, and the aperture 25 of the carriage 3 is transmitted. The position of the carriage 3 is controlled so that is at a predetermined position directly below the glass window 2b. In the present embodiment, the position of the carriage 3 is fixed, and the document 36 is conveyed by the ADF to read the image.

Further, the lamp 24 is turned on and A
The rotation of an ADF drive motor (not shown) independently provided in the DF unit 12 is started. At this point, ADF
The rotation target speed of the drive motor (not shown) corresponds to the minimum resolution supported by the image reading device, and the maximum speed of the device corresponds to this. Also,
The direction of rotation of the ADF drive motor (not shown) is the original 36
Is conveyed from the document tray 13 to the glass window 2b, and hereinafter, the document conveyance in this direction is defined as the forward direction. In addition, the glass window 2b, that is, the direction in which the original 36 is conveyed in the opposite direction to the reading position is defined as the reverse direction.

The carrying roller 19 is coupled to an ADF drive motor (not shown) via a speed reducing mechanism (not shown), and faces the carrying roller 19 as the ADF drive motor (not shown) rotates. The guide rollers 20 and 21 start rotating. When the rotation of the ADF drive motor (not shown) reaches the target speed, the clutch mechanism (not shown) is controlled to rotate the paper feed roller 16 and the reverse roller 17, and the original 36 set on the original tray 13 Start transportation. The reverse roller 17 suppresses so-called double feeding, in which a plurality of originals are simultaneously conveyed, by utilizing the difference in friction between the roller and the original surface.

FIG. 3 is a view showing a state in which the document 36 is sandwiched between the transport roller 19 and the guide roller 20 after reaching the position of the transport path switching means 29. Hereinafter, the description will be continued with reference to FIG.

When the document 36 reaches the position of the transport path switching means 29, the transport path switching means 29 is rotated in the direction d3 by the driving force applied to the document 36, so that the document 36 is moved.
Can pass through the transport path switching means 29 without being obstructed in transport.

When the leading edge of the transported document 36 is detected by the document edge detection sensor 18, the clutch mechanism (not shown) is controlled to stop the drive transmission to the paper feed roller 16 and the reverse roller 17. At this point, the document 36 is reliably sandwiched between the transport roller 19 and the guide roller 20 facing the transport roller 19, and subsequent document transport is performed by the transport roller 19, and the paper feed roller 16 acts as a tension roller.

Next, the process of detecting the leading edge of the document 36 by the document edge detection sensor 18 and generating the timing to start reading will be described. In order to simplify the following description, it is assumed that the ADF drive motor (not shown) is a stepping motor, and the control system (not shown) of the image reading apparatus is a means for switching the excitation signal of the stepping motor and the excitation signal And a means for counting the number of times of switching.

Since the aperture 25 of the carriage 3 arranged immediately below the glass window 2b is always present in a predetermined position, the aperture 2 is detected from the document edge detecting sensor 18.
5, that is, the distance to the image reading position is fixed. Further, since the reading range of the original is specified by an external host (not shown), the control system (not shown) of the image reading apparatus detects when the original edge detection sensor 18 detects the leading edge of the original 36. Then, it is calculated how many more times the excitation signal for the ADF drive motor (not shown) is switched to reach the top of the document reading range on the aperture 25. In the following description, this timing is referred to as the image reading start timing.

Further, since the current original document conveyance speed (maximum speed of the apparatus) and the original document conveyance speed corresponding to the image reading resolution (set by the external host) are known, the number of times the excitation signal can be changed to change the original document. Calculates whether to reach the position where the document transport speed starts to decrease. In the following description, this timing is referred to as deceleration start timing.

Document 3 that has passed the document edge detection sensor 18
6 is conveyed at the maximum speed of the apparatus until the deceleration start timing. Image reading device control system (not shown)
Counts the number of times the excitation signal is switched, and starts decelerating an ADF drive motor (not shown) when the deceleration start timing is reached.

Every time the output of the excitation signal is switched, the generation period of the excitation signal is increased by a specified ratio,
ADF drive motor (not shown) linearly decelerates
The drive speed of the F drive motor (not shown) corresponds to the scanning resolution of the image.
When deceleration is reached, deceleration is stopped, and thereafter, the vehicle is driven at a constant speed.

Next, when the image reading start timing is reached, reading of the original image is started. The transported original 36 is illuminated by the lamp 24 through the glass window 2b, the reflected light from the original 36 is reflected by the reflection mirror 26, and is imaged on the color image sensor 27 by the imaging lens 28 to be an electric signal. To be converted.

FIG. 4 is a view showing the situation when the original 36 reaches the vicinity of the glass window 2b. Hereinafter, the description will be continued with reference to FIG.

When the document 36 is conveyed in the forward direction, if the document 36 projects into the first step portion 37 in the vicinity of the glass window 2b, the document 36 will not be conveyed any more and a so-called jam will occur. However, by rotating the ADF drive motor (not shown) in the forward direction, the first document guide member 31 moves to the shaft 33.
Since the document 36 is configured to be displaced in the direction d4 around the center, the transport direction of the leading edge of the document 36 is biased toward the center of the glass window 2b rather than the first step portion 37, and the first step portion 3
Pass 7 smoothly. Further, since the second document guide member 32 is configured to be displaced in the direction d5 about the shaft 34, the transport passage is opened widely, and the document 36 is moved.
After passing through the glass window 2b, is reliably transported in the direction of the transport roller 19 and the guide roller 21.

When the image reading in the reading range designated by the external host (not shown) is completed, the feeding speed of the original 36 is accelerated to the maximum speed of the apparatus while keeping the same feeding direction. Eventually, the leading edge of the document 36 is nipped by the transport roller 19 and the guide roller 21 facing the transport roller 19, and the document 36 is discharged by the discharge roller 23 to the discharge tray 14.

On the other hand, after the trailing edge of the document 36 is detected by the document edge detection sensor 18, an external host (not shown)
When the original detection sensor 15 detects the original at this time, the clutch mechanism (not shown) is controlled again to rotate the paper feed roller 16 and the reverse roller 17, and the original is read. The conveyance of the original document 36 set on the tray 13 is started.

By repeating the above operation, the originals 36 stacked on the original tray 13 are sequentially conveyed onto the glass window 2b and the image is read.

Next, a second reading mode in which the original 36 set on the original tray 13 is read and then conveyed in the reverse direction without discharging to the paper discharge tray 14 to prepare for re-reading will be described.

When an external host (not shown) outputs a command for instructing the original 36 to be taken into the machine, the ADF unit 12 conveys the original 36 to a predetermined position in the forward direction and then in the reverse direction. The document is conveyed to the document storage unit 35 and stored in the document storage unit 35. An instruction issued from an external host (not shown) to instruct the in-machine capture of a document is, for example, SCSI (Small Computer).
OBJECT POSITION specified for the scanner device by the System Interface standard
The paper feed parameters and the like of the command correspond.

First, the paper feeding operation will be described with reference to FIGS. A paper feed is instructed from an external host (not shown), and the original 3 is placed on the original tray 13 of the ADF unit 12.
When 6 is set and the document detection sensor 15 detects the document 36, the ADF drive motor (not shown) starts rotating. At this point, the rotation target speed of the ADF drive motor (not shown) corresponds to the minimum resolution supported by the image reading apparatus, and the maximum speed of the apparatus corresponds to this. Also, an ADF drive motor (not shown)
The rotation direction of is set to the forward direction in which the document 36 is conveyed from the document tray 13 to the glass window 2b.

The carrying roller 19 is a speed reducing mechanism (not shown).
Is connected to an ADF drive motor (not shown) via the ADF drive motor (not shown), and as the ADF drive motor (not shown) rotates, the transport roller 19 and the guide rollers 20, 21 facing the transport roller 19 start rotating. When the rotation of the ADF drive motor (not shown) reaches the target speed, the clutch mechanism (not shown) is controlled to rotate the paper feed roller 16 and the reverse roller 17, and the original 36 set on the original tray 13 Start transportation. The reverse roller 17 suppresses so-called double feeding, in which a plurality of originals are simultaneously conveyed, by utilizing the difference in friction between the roller and the original surface.

FIG. 3 is a view showing a situation in which the document 36 is nipped by the transport roller 19 and the guide roller 20 after reaching the position of the transport path switching means 29. Hereinafter, the description will be continued with reference to FIG.

When the document 36 reaches the position of the transport path switching means 29, the transport path switching means 29 is rotated in the direction d3 by the driving force applied to the document 36, so that the document 36 is moved.
Can pass through the transport path switching means 29 without being obstructed in transport.

When the leading edge of the conveyed document 36 is detected by the document edge detecting sensor 18, the clutch mechanism (not shown) is controlled to stop the drive transmission to the paper feed roller 16 and the reverse roller 17. At this point, the document 36 is reliably sandwiched between the transport roller 19 and the guide roller 20 facing the transport roller 19, and subsequent document transport is performed by the transport roller 19, and the paper feed roller 16 acts as a tension roller.

FIG. 4 is a diagram showing the situation when the original 36 reaches the vicinity of the glass window 2b. Hereinafter, the description will be continued with reference to FIG.

When the document 36 is conveyed in the forward direction, if the document 36 projects into the first step portion 37 in the vicinity of the glass window 2b, the document 36 is not conveyed any more, and a so-called jam occurs. However, by rotating the ADF drive motor (not shown) in the forward direction, the first document guide member 31 moves to the shaft 33.
Since the document 36 is configured to be displaced in the direction d4 around the center, the transport direction of the leading edge of the document 36 is biased toward the center of the glass window 2b rather than the first step portion 37, and the first step portion 3
Pass 7 smoothly. Further, since the second document guide member 32 is configured to be displaced in the direction d5 about the shaft 34, the transport passage is opened widely, and the document 36 is moved.
After passing through the glass window 2b, is reliably transported in the direction of the transport roller 19 and the guide roller 21.

FIG. 5 is a diagram showing the situation when the trailing edge of the conveyed document 36 is detected by the document edge detecting sensor 18. Hereinafter, the description will be continued with reference to FIG.

When the trailing edge of the original 36 passes through the transport path switching means 29, the transport path switching means 29 is urged by its own weight in the direction d2.

When the document is further conveyed and the trailing edge of the document 36 is detected by the document edge detection sensor 18, a control system (not shown) of the image reading apparatus is operated by an ADF drive motor (not shown). ), How many more times the excitation signal is switched to reach the rear end of the document 36 on the glass window 2b. In the following description, this timing will be referred to as the reverse conveyance start timing.

When the reverse conveyance start timing is reached, the ADF drive motor (not shown), which has been conveying the document 36 in the forward direction until now, is once stopped, and then the document 36 is conveyed in the reverse direction. The transport speed of the original document 36 at this time is set to the maximum speed of the apparatus.

FIG. 6 is a diagram showing the situation at the time when the conveyance of the original document 36 in the reverse direction is started. Hereinafter, the description will be continued with reference to FIG.

By rotating an ADF drive motor (not shown) in the opposite direction, the second document guide member 32 is moved to the shaft 34.
The original 36 is biased toward the center of the glass window 2b.
Further, the first document guide member 31 is configured to be displaced in the direction d6 about the shaft 33, the transport passage is opened widely, and the document 36 passes through the glass window 2b,
The document is reliably conveyed toward the document edge detection sensor 18. Even if the original 36 is conveyed in the forward direction over the glass window 2b and the second step 38, the second original guide member 32 causes the original 36 to move the original 36 in the glass window 2b during the reverse conveyance.
Since the document 36 is urged toward the center of the document, the document 36 is easily transported over the second step 38.

FIG. 7 is a diagram showing the situation at the time when the document edge detection sensor 18 detects the leading edge of the document 36 conveyed in the reverse direction. Here, the leading edge of the document refers to an end portion first detected by the document edge detection sensor 18 when the document is transported from the document tray 13 in the forward direction regardless of the document transport direction. Further, the rear end means an end portion in the direction opposite to the front end. Hereinafter, the description will be continued with reference to FIG. 7.

The original document 36 will eventually have the first original document guide member 31.
And reaches the document edge detection sensor 18, and the trailing edge of the document 36 is detected by the document edge detection sensor 18. The output of the document edge detection sensor 18 indicates that “document is present” while the document 36 is passing the sensor position. A control system (not shown) of the image reading apparatus further conveys the document 36 in the reverse direction, and continues the conveyance until the leading edge of the document 36 is detected by the document edge detection sensor 18. After the leading edge of the document 36 is detected by the document edge detection sensor 18, the output of the document edge detection sensor 18 indicates "no document". When the document edge detection sensor 18 detects "no document", the control system (not shown) of the image reading apparatus temporarily stops the conveyance of the document 36. Then, the document 36 is conveyed in the forward direction again, this time with respect to the front end of the document 36 until the document edge detection sensor 18 detects "document present". Original document 36 at this time
The transport speed of is at least a predetermined speed lower than the maximum speed of the apparatus.

FIG. 8 is a view showing the re-readable state of the original document in the above-mentioned second reading mode.
In this state, the document edge detection sensor 18 indicates "document present".
When a document reading command is issued from an external host (not shown), it can be determined whether or not the document exists inside the image reading apparatus.

Next, the operations of the first document guide member 31 and the second document guide member 32, which are generally described in the first reading mode and the second reading mode, will be described below.

FIG. 9 shows the first original guide member 31 and the second original guide member 31.
FIG. 6 is a diagram showing a configuration in the vicinity of a document guide member 32.
The guide position when the F drive motor (not shown) is rotated in the forward direction is shown.

In FIG. 9, the power transmission member 39 rotates together with the shaft 40 to transmit the power of the transport roller 19. The cam 41 is the same shaft 4 as the power transmission member 39.
0. The spring clutch 42 is connected to the cam 41 and wound around the shaft 40. The power transmission lever 43 is provided on the first document guide member 31.
To transmit power. The biasing member 44 is composed of a spring or the like, and biases the power transmission lever 43 upward. The joint member 45 transmits the displacement of the first document guide member 31 to the second document guide member 32. Power transmission lever 4
A stopper 46 is provided at the end of 3.

In this embodiment, the power transmission member 39, the shaft 40, the cam 41, the spring clutch 42, the power transmission lever 43, the urging member 44 and the joint member 45 constitute a displacement means.

When the ADF drive motor (not shown) is rotated in the forward direction, the carry roller 19 rotates in the direction d8. The rotation of the transport roller 19 is transmitted to the shaft 40 by the power transmission member 39 composed of a gear or the like, and the power transmission member 39 and the shaft 40 rotate in the direction d9.
Although the spring clutch 42 is wound around the shaft 40, the spring clutch 42 does not transmit the driving force to the cam 41 when the shaft 40 is rotating in the direction d9 because the spring is released. When the cam 41 is at the position shown in FIG. 9, the first document guide member 31 moves toward the shaft 3
It will be fixed in the direction d4 with 3 as the center.

When the first document guide member 31 is displaced in the direction d4, the leading edge of the transported document 36 is moved to the first step 3
It is biased closer to the center of the glass window 2b than 7 and smoothly passes through the first step portion 37. Further, since the second document guide member 32 is fixed in the direction d5 about the shaft 34 by the first document guide member 31 and the joint member 45, the transport passage is largely opened on the downstream side in the transport direction of the document 36. Then, after the original 36 passes through the glass window 2b,
It is reliably transported in the direction of the transport roller 19 and the guide roller 21.

FIG. 10 is a view showing the structure in the vicinity of the first original guide member 31 and the second original guide member 32, where A
The guide position when the DF drive motor (not shown) is rotated in the reverse direction is shown. Since the configuration in FIG. 10 is the same as that in FIG. 9, description thereof will be omitted.

When the ADF drive motor (not shown) is rotated in the reverse direction, the carry roller 19 rotates in the direction d10. The rotation of the transport roller 19 is transmitted to the shaft 40 by the power transmission member 39 composed of a gear or the like, and the power transmission member 39 and the shaft 40 rotate in the direction d11. A spring clutch 42 is wound around the shaft 40.
Is rotating in the direction d11, the spring wraps around the shaft 40 and transmits the driving force to the cam 41. Therefore, the cam 41 rotates in the direction d11 together with the shaft 40 against the tension of the biasing member 44, and the power transmission lever 43 is displaced downward as the cam 41 rotates. Eventually, as the cam 41 rotates, the pawl formed at the tip of the spring clutch 42 engages the stopper 46, and the pawl of the spring clutch 42 is biased in the direction opposite to the direction d11. Due to this biasing pressure, the spring of the spring clutch 42 is loosened, and no more rotational force is applied to the cam 41. Therefore, the displacement of the power transmission lever 43 is stopped when the claw of the spring clutch 42 is engaged with the stopper 46. On the other hand, the first document guide member 31 is displaced in the direction d6 as the power transmission lever 43 is displaced. Further, the displacement of the first document guide member 31 is transmitted to the second document guide member 32 by the joint member 45, and the second document guide member 32 is displaced in the direction d7.

When the second document guide member 32 is located at the position of the direction d7, the end of the document 36 conveyed in the opposite direction is biased toward the center of the glass window 2b rather than the second step 38. It smoothly passes through the second step portion 38. Further, when the first document guide member 31 is present at the position of the direction d6, the transport passage is largely opened on the downstream side in the transport direction of the document 36, and the document 36 is reliably transported in the opposite direction after passing through the glass window 2b. To be done.

Next, in the second reading mode, when the manuscript 36 is in a re-readable state and a manuscript read command is issued from an external host (not shown), FIG. And FIG. 18 will be described.

At the time when the paper feeding operation is completed, the status of the apparatus is as shown in FIG. After setting the reading resolution, reading range, etc., if a document reading command is issued, the document 36 does not exist in the document tray 13 of the ADF unit 12, and the document edge detection sensor 18 detects the document, The lamp 24 is turned on and the rotation of an ADF drive motor (not shown) independently provided in the ADF unit 12 is started. At this point, the target rotation speed of the ADF drive motor (not shown) is at least a predetermined speed lower than the maximum speed of the device,
The rotation direction of the ADF drive motor (not shown) is opposite.

The document transportation in the reverse direction is continued until the leading edge of the document 36 is detected by the document edge detecting sensor 18. After the leading edge of the document 36 is detected by the document edge detection sensor 18, the output of the document edge detection sensor 18 indicates "no document". When the document edge detection sensor 18 detects "no document", the control system (not shown) of the image reading apparatus temporarily stops the conveyance of the document 36. This situation is shown in Figure 7.
Since the state is completely different from the state described above, the description will be continued below with reference to FIG. 7.

After the conveyance of the document 36 is stopped, the document 36 is conveyed again in the forward direction at the maximum speed of the apparatus.

After the document 36 is taken into the machine by the paper feeding operation in the second reading mode, the document 36 in the machine is conveyed by rotating the ADF drive motor (not shown). The control of the clutch mechanism (not shown) performed when the document 36 is conveyed is unnecessary.

Next, the process of detecting the leading edge of the document 36 by the document edge detection sensor 18 and generating the timing for starting reading will be described. To simplify the following explanation,
The ADF drive motor (not shown) is a stepping motor, and the control system (not shown) of the image reading device has means for switching the excitation signal of the stepping motor and means for counting the number of times the excitation signal is switched. And

Since the aperture 25 of the carriage 3 arranged immediately below the glass window 2b is always present at a prescribed position, the distance from the document edge detecting sensor 18 to the aperture 25, that is, the image reading position is fixed. Further, since the reading range of the original is instructed from an external host (not shown), the control system (not shown) of the image reading apparatus causes the original end detection sensor 18 to detect the original 36.
When the leading edge of the document is detected, how many times the excitation signal for the ADF drive motor (not shown) is switched, the document 36
It is calculated whether or not the beginning of the reading range of 1 reaches the aperture 25. In the following description, this timing is referred to as the image reading start timing.

Further, since the current original document conveyance speed (maximum speed of the apparatus) and the original document conveyance speed corresponding to the image reading resolution (set by the external host) are known, the number of times the excitation signal can be changed to change the original document. Calculate whether to reach the position to start decelerating the transport speed. In the following description, this timing is referred to as deceleration start timing.

Document 3 that has passed the document edge detection sensor 18
6 is conveyed at the maximum speed of the apparatus until the deceleration start timing. Image reading device control system (not shown)
Counts the number of times the excitation signal is switched, and starts decelerating an ADF drive motor (not shown) when the deceleration start timing is reached.

Each time the output of the excitation signal is switched, the generation period of the excitation signal is increased by a specified ratio,
ADF drive motor (not shown) linearly decelerates
The drive speed of the F drive motor (not shown) corresponds to the scanning resolution of the image.
When it reaches, the deceleration is stopped, and thereafter, it is driven at a constant speed.

Next, when the image reading start timing is reached, reading of the original image is started. The transported original 36 is illuminated by the lamp 24 through the glass window 2b, the reflected light from the original 36 is reflected by the reflection mirror 26, and is imaged on the color image sensor 27 by the imaging lens 28 to be an electric signal. To be converted.

FIG. 11 is a diagram showing the situation when the original 36 once taken into the apparatus reaches the vicinity of the glass window 2b in the above-mentioned second reading mode. Hereinafter, the description will be continued with reference to FIG.

When the document 36 is transported in the forward direction, if the document 36 projects into the first step portion 37 near the glass window 2b, the document 36 is not transported any more, and a so-called jam occurs. However, by rotating the ADF drive motor (not shown) in the forward direction, the first document guide member 31 moves to the shaft 33.
Since the document 36 is configured to be displaced in the direction d4 around the center, the transport direction of the leading edge of the document 36 is biased toward the center of the glass window 2b rather than the first step portion 37, and the first step portion 3
Pass 7 smoothly. Further, since the second document guide member 32 is configured to be displaced in the direction d5 about the shaft 34, the transport passage is opened widely, and the document 36 is moved.
After passing through the glass window 2b, is reliably transported in the direction of the transport roller 19 and the guide roller 21. For example, the manuscript 36
It is assumed that the reading range up to the rear end of is specified by an external host (not shown). When the image reading in the reading range is completed, the control system of the image reading device is set to AD.
The F drive motor (both not shown) is once stopped.

Next, the original 36 is conveyed in the reverse direction. The conveyance speed of the original document 36 at this time is set to the maximum speed of the apparatus.

Since this situation is equivalent to the case shown in FIG. 6, the description will be continued below with reference to FIG.

The transport path switching means 29 is driven by its own weight in the direction d2,
That is, the document 36 conveyed in the opposite direction is loaded with the document storage section 35.
It is urged in the guiding direction.

By rotating an ADF drive motor (not shown) in the opposite direction, the second document guide member 32 is rotated by the shaft 34.
The original 36 is biased toward the center of the glass window 2b.
Further, the first document guide member 31 is configured to be displaced in the direction d6 about the shaft 33, the transport passage is opened widely, and the document 36 passes through the glass window 2b,
The document is reliably conveyed toward the document edge detection sensor 18. Even if the original 36 is conveyed in the forward direction over the glass window 2b and the second step 38, the second original guide member 32 causes the original 36 to move the original 36 in the glass window 2b during the reverse conveyance.
Since the document 36 is urged toward the center of the document, the document 36 is easily transported over the second step 38.

FIG. 7 is a diagram showing a situation at the time when the document edge detecting sensor 18 detects the leading edge of the document 36 conveyed in the reverse direction. Here, the leading edge of the document refers to an end portion first detected by the document edge detection sensor 18 when the document is transported from the document tray 13 in the forward direction regardless of the document transport direction. Further, the rear end means an end portion in the direction opposite to the front end. Hereinafter, the description will be continued with reference to FIG. 7.

The original document 36 will soon have the first original document guide member 31.
And reaches the document edge detection sensor 18, and the trailing edge of the document 36 is detected by the document edge detection sensor 18. The output of the document edge detection sensor 18 indicates that “document is present” while the document 36 is passing the sensor position. A control system (not shown) of the image reading apparatus further conveys the document 36 in the reverse direction, and continues the conveyance until the leading edge of the document 36 is detected by the document edge detection sensor 18. After the leading edge of the document 36 is detected by the document edge detection sensor 18, the output of the document edge detection sensor 18 indicates "no document". When the document edge detection sensor 18 detects "no document", the control system (not shown) of the image reading apparatus temporarily stops the conveyance of the document 36. Then, the document 36 is conveyed in the forward direction again, this time with respect to the front end of the document 36 until the document edge detection sensor 18 detects "document present". Original document 36 at this time
The transport speed of is at least a predetermined speed lower than the maximum speed of the apparatus.

In this state, the document edge detecting sensor 18 detects "document present", and when a document reading command is issued from an external host (not shown), the document exists inside the image reading apparatus. It can be determined whether or not to do.

As described above, once the original 3
After capturing 6, the document 36 is stored in the re-readable position, that is, the document storage unit 35 every time the image is read, so that the same document can be read a plurality of times.

FIG. 12 is a view showing a case where the original is stored in the original storage section 35 and the original is set on the original tray 13.

Next, referring to FIG. 12, the operation when an original reading command is issued from an external host (not shown) when the originals are set in both the original storage section 35 and the original tray 13 will be described. Explain. In FIG. 12, the second document 47 is set on the document tray 13. Hereinafter, the original document 36 stored in the original document storage unit 35 will be referred to as a first original document for distinction.

After setting the reading resolution, the reading range, etc., an instruction to read the original is issued, and the first original 3 stored in the original storage unit 35 by the original edge detection sensor 18 is read.
6 is detected, and the second document 47 set on the document tray 13 is detected by the document detection sensor 15,
The lamp 24 is turned on and the rotation of an ADF drive motor (not shown) independently provided in the ADF unit 12 is started. At this point, the target rotation speed of the ADF drive motor (not shown) is at least a predetermined speed lower than the maximum speed of the device, and
The drive motor (not shown) rotates in the opposite direction. At this point, the clutch mechanism (not shown) does not control the connected state. Therefore, only the first original 36 is conveyed thereafter.

That is, the document edge detection sensor 18 detects the first document 36 stored in the document storage section 35, and the document detection sensor 15 detects the second document 47 set on the document tray 13. Document storage unit 35
The first original 36 stored in
The conveyance of the second document 47 set on the document tray 13 is prohibited.

The document conveyance in the reverse direction is continued until the leading edge of the first document 36 is detected by the document edge detecting sensor 18. The leading edge of the first document 36 is the document edge detection sensor 18
After being detected by (1), the output of the document edge detection sensor 18 indicates "no document". When the document edge detection sensor 18 detects "no document", a control system (not shown) of the image reading apparatus temporarily stops the conveyance of the first document 36.

After stopping the conveyance of the first original 36,
The original 36 is again conveyed in the forward direction at the maximum speed of the apparatus.

By prohibiting the operation of the clutch mechanism (not shown) as described above, even if there are a plurality of originals (second originals 47) in the original tray 13, the originals (first If the first document 36) exists, the reading of the first document 36 can be executed.

The subsequent operation is completely the same as the operation when an original reading command is issued from an external host (not shown) when the original 36 is ready to be read again in the above-mentioned second reading mode. Since they are equivalent, description will be omitted.

Next, the process of ejecting the original document 36 once stored in the original document storage section 35 once taken into the machine will be described. 1 and 12 are used for the description. When the manuscript 36 is stored in the position shown in FIG. 12, that is, in the re-readable position, when an external host (not shown) outputs an instruction to discharge the manuscript, the AD
The F unit 12 discharges the document 36 to the paper discharge tray 14. The command issued from an external host (not shown) to instruct the ejection of the in-machine document is, for example, SCS.
I (Small Computer System I
The paper ejection parameters and the like of the OBJECT POSITION command specified for the scanner device by the interface standard are applicable.

When the external host (not shown) issues a sheet discharge instruction, the ADF drive motor (not shown) starts rotating. The rotation speed of the ADF drive motor (not shown) is the maximum speed that the device has. The rotation direction of the ADF drive motor (not shown) is the forward direction. The conveyance of the document is continuously detected by the document discharge detection sensor 22 in the “document present” state for a predetermined period, then detected as “no document”, and the predetermined period elapses.
Is carried out until the sheet is completely conveyed to the discharge tray 14.

As described above, as the operation of the second reading mode, the process of taking in (feeding) a document, reading it, and discharging it to the outside of the device (paper ejection) have been described in detail.

Next, the document attribute determining function will be described in detail. First, it demonstrates using FIG. The document attribute determination is processed in the above-described process of taking in (feeding) a document. In the paper feeding operation, the document 36 is conveyed in the forward direction at the maximum speed of the apparatus, the stop timing is generated by the document edge detection sensor 18, and after the stop, the document 36 is conveyed in the reverse direction at the maximum speed of the apparatus to convey the document 36. This is executed in the sequence of storing in the document storage section 35, but during the process of transporting the document 36, almost all the image area of the document 36 is in the glass window 2.
Pass over b. Therefore, at this time, the original 36 can be illuminated by the lamp 24 to read the image.

FIG. 13 is a block diagram of the image data processing unit of the image reading apparatus. In FIG. 13, the color image sensor 27 outputs analog image information for each R, G, B color unit. The amplifier 48 amplifies the analog image information output from the color image sensor 27. A /
The D converter 49 converts the output of the amplifier 48 into a digital signal. The shading calculation unit 50 normalizes the digital image signal with respect to the dynamic range of white and black.
The resolution conversion unit 51 converts the resolution of the color image sensor 27 in the main scanning direction (the direction in which the pixels of the image sensor are arranged) to the resolution designated by an external host (not shown).
The image memory 52 functions as a buffer that temporarily stores image data. CPU (Central Processing Unit) 53
Manages image data processing hardware. CP
The peripheral circuit of U53 is configured so that the contents of the image memory 52 can be read / written. DMA54
DMAs the image data stored in the image memory 52.
The data is transferred to the interface unit 55 by (Direct Memory Access) transfer. Further, the interface unit 55 is connected to, for example, an external host (not shown).

When executing the document attribute determination, the CPU 53 sets a parameter for the resolution conversion unit 51 so as to convert the image data into, for example, 60 dpi (dot per inch). For example, the basic resolution of the color image sensor 27 in the main scanning direction is 600, for example.
If it is dpi, the image data in the main scanning direction is decimated to 1/10.

In the case of this image reading apparatus, since the image reading in the sub-scanning direction orthogonal to the main scanning direction is performed in a predetermined line cycle, the resolution in the sub-scanning direction is completely equal to the document conveying speed. Dependent. That is, if the document is conveyed at a high speed, the resolution in the sub-scanning direction is lowered, and conversely, if the document is conveyed at a low speed, the resolution in the sub-scanning direction is increased.

When the original attribute determination is executed, the original conveying speed is set so that the resolution in the sub-scanning direction is read at, for example, 30 dpi.

As described above, the main scanning direction is 60 dp.
i, the image reading condition of 30 dpi in the sub-scanning direction is set, the document is conveyed, and the image data processing unit is operated at a predetermined timing. Then, the image read by the color image sensor 27 is stored in the image memory 52. Data is stored in a so-called dot-sequential order in the order of R, G, and B for each pixel, for example.

This image reading apparatus is mainly an apparatus for reading a letter size color original document, but when the reading conditions are set to 60 dpi in the main scanning direction and 30 dpi in the sub scanning direction, each bit is 8 bits / When the image of the entire letter size is read with the data amount of pixels, the total data amount becomes about 504 kbytes. In this image reading device, the image memory 52 is equipped with 512 kbytes,
With the above-mentioned reading resolution, it is possible to store all the read contents for one original in the image memory 52. In a normal reading operation, the image memory 52 is used as a buffer, and the image data input to the image memory 52 is immediately transferred to the interface unit 55 by the DMA 54.
The image data is stored in the image memory 52 and is not output to the outside when the document attribute determination is performed. Hereinafter, a mode for document attribute determination that does not output image data to the outside will be referred to as a third reading mode.

The processing for the image data stored in the image memory 52 will be described below. FIG. 14 is a flowchart showing the document attribute determination process. Original attribute determination process is C
This is performed by the PU 53 accessing the image data on the image memory 52.

In step S1, R image data in the main scanning direction, G data for the image data stored in the image memory 52 are read.
Data and B data are averaged every two pixels. The document is read in advance at 60 dpi in the main scanning direction, but the main scanning direction is also converted to 30 dpi by performing this scanning.

The read pixels in the main scanning direction are obtained by simply thinning out the output of the color image sensor 27.
Depending on the structural accuracy of the color image sensor 27 and the reading condition, for example, a chromatic component may appear in a portion where an edge of a character or a line drawing is originally achromatic. here,
In this image reading apparatus, when the document attribute is determined, the main scanning direction is read in advance with a resolution higher than that in the sub scanning direction, and the resolution is converted to be equal to the resolution in the sub scanning direction by software processing to reduce the appearance of colored portions. . On the other hand, in the sub-scanning direction, the reading cycle of each line is determined only by the moving speed of the document, and the image information during the reading period of one line is integrated, so that the color component is emphasized at the edge portion. There is no such thing.

In step S2, YC separation is performed on the image data converted to 30 dpi in both the main scanning direction and the sub scanning direction. By this processing, the image data is separated into the luminance component Y and the hue components I and Q. Generally, conversion from RGB data to YIQ data by digital calculation is performed by the matrix calculation of (Equation 1).

[0149]

[Equation 1]

However, since multiplication has a speed limit in the processing capacity of the CPU, each element of the operation matrix is multiplied by 1000 with respect to the operation matrix of (Equation 1) as shown in (Equation 2), and the accuracy is increased. If the image data is 8 bits per pixel, a value obtained by multiplying each element of the operation matrix by 0 to 255 is created as a LUT (lookup table).

[0151]

(Equation 2)

At the time of actual calculation, RGB data is converted into YIQ data only by memory access and addition. FIG. 15 is a diagram showing an LUT created for the element [1, 1] = 299 of the operation matrix shown in (Equation 2). The values of the hue components I and Q calculated by the above method are between -127000 and +18000. Further, the value of the brightness component Y is 0 to 255000.

In step S3, the appearance distribution of the hue components I and Q in the main scanning direction is checked. If the image data of the achromatic component is converted to YIQ data, 2
The values of the hue components I and Q are near 0 regardless of the value image and the multivalued image. In the present embodiment, the hue components I and Q are
Is within ± 1280, the corresponding pixel is determined to be an achromatic pixel, and the other pixels are determined to be chromatic pixels. Since a color image such as a photograph has a continuous colored region, the hue components I and Q are checked pixel by pixel for each line. For example, if the colored pixel is detected 10 times in a row, the target pixel is the colored pixel. To judge. The number of times of 10 times corresponds to about 8.5 mm at 30 dpi. Therefore, in this embodiment, a color image is determined when the original has a color image area exceeding 8.5 mm. Further, in the present determination processing, if it is determined that even one line is a color image during the checking of each line, the process proceeds to step S4, and the determination ends. If it is not judged as a color image even if all the lines are checked, the process proceeds to step S5.

At step S3, the hue components I and Q are checked, but at step S5 and thereafter,
On the assumption that the target image is a monochrome image, the luminance component Y is processed to determine whether the target image is a binary image (character or line drawing) or a multivalued image.

First, in step S5, the luminance component Y of the image data is targeted for binarization by the first threshold value, and the number of pixels determined to be black is counted. Then, the number N1 thereof is stored. For example, if the value 0 of 8-bit image data indicates black and 255 indicates white, the first
The threshold value of is set to a value at which the appearance frequency of black becomes relatively high, for example, about 200.

Next, in step S6, the luminance component Y of the image data is again targeted, and a binary value is set using the second threshold value set so that the frequency of appearance of black is reduced by the first threshold value. Then, the number of pixels determined to be black is counted. Then, the number N2 thereof is stored. For example, 8
If the value 0 of the bit image data indicates black and 255 indicates white, the first threshold value is set to a value at which the appearance frequency of black is relatively low, for example, about 50.

By the way, in the above embodiment, step S
Although the processing steps of 5 and S6 are separated, two threshold values may be held in advance and the number of blacks corresponding to the two threshold values may be simultaneously counted in one memory search.

In step S7, the numbers N1 and N2 of black pixels calculated in steps S5 and S6 are compared. If the original is a photograph original (multivalue original), the ratio between the number N1 and the number N2, that is, N1 / N2 <10 or so. This is because in an image composed of continuous gradations, the number of black pixels does not change dramatically even if the threshold value is changed. However, in the case of a manuscript (binary manuscript) whose entire surface is characters or line drawings, the value of the number N2 becomes extremely small, and the ratio of the number N1 and the number N2, that is, N
1 / N2 ≧ 1000. This is because the resolution of the image data read at the time of document attribute determination is low, and because the image data for normal size characters and the like are all at an intermediate level due to the averaging process performed in step S1, depending on the document, This is because even if black is not counted at all. Further, there are cases where a multi-valued image and a binary image are mixed in the original, and in that case, the ratio of the number N1 and the number N2 varies between 10 and 1000. In the present embodiment, the number N1 and the number N that distinguish a binary image from a multi-valued image.
The ratio with 2 is 100.

In the embodiment, two threshold values are used, the number of black pixels is counted for each threshold value, and the two count values are compared to generate a multi-valued image and a binary image. Although it is determined, the determination accuracy can be improved by, for example, having a threshold value of 3 to 4 or more and tracking the change in the number of black pixels in detail. Also, the number N1 and the number N2
It is conceivable to improve accuracy by not only referring to the ratio of the number of black pixels to the two threshold values, that is, referring to the difference in the number of black pixels.

As described above, in the third reading mode, the document attribute determination can be executed by utilizing the sequence of the paper feeding operation. At the time when the document is designated to be fed and the document is stored in the document storage unit 35, the external host (not shown) may send, for example, a SCSI command (eg, mode).
It is possible to know the document attribute determination result by using (sense etc.). Then, when the next document is read, the scanning operation based on the document attribute determination result can be executed.

As described above, in the above-described embodiment, the ADF unit 12 is used to convey the once read document at a high speed in the reverse direction and store it again in a readable position. It becomes possible to read. Therefore, it is possible to deal with a usage pattern in which the main scan is executed after the pre-scan without any problem. The user only needs to set the document 36 on the document tray 13 for substantially all the operations, which improves the work efficiency and improves the ADF.
You will be able to make full use of the benefits of wearing.

Also, the attribute of the original is determined at any time,
Even when a multi-valued image color original document, a multi-valued image monochrome original document, and a binary image monochrome original document are set together in the ADF, the user does not need to make any pre-settings, and the work such as filing is extremely efficient. You can do it well.

[0163]

As described above, according to the present invention, a document that has been read once can be conveyed in the reverse direction and stored at a position where it can be read again. Can be read multiple times.
Therefore, it is possible to deal with a usage pattern in which the main scan is executed after the pre-scan without any problem. Further, since the user only has to set the document on the document tray for substantially all the work, the work efficiency is improved and the ADF
You can take advantage of wearing.

Before the prescan operation, the original is conveyed from the original tray in the forward direction, the attribute of the original read by the reading means is determined, the original is conveyed in the reverse direction, and the original is stored in a rereadable position. Is possible. Therefore, even when documents having various attributes are mixedly set on the document tray, the user does not need to make any setting in advance.
Work such as filing can be performed extremely efficiently.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an image reading apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the ADF unit shown in FIG.

FIG. 3 is a diagram showing a situation where a document is nipped by a transport roller and a guide roller after reaching a position of a transport path switching unit.

FIG. 4 is a diagram showing a situation when a document reaches near a glass window.

FIG. 5 is a diagram showing a situation where a trailing edge of a conveyed document is detected by a document edge detection sensor.

FIG. 6 is a diagram showing a situation at the time when the conveyance of a document in the reverse direction is started.

FIG. 7 is a diagram showing a situation at the time when a document edge detection sensor detects the leading edge of a document conveyed in the reverse direction.

FIG. 8 is a diagram showing a state in which a document can be read again in a second reading mode.

FIG. 9 is a diagram showing a configuration in the vicinity of a first document guide member and a second document guide member when an ADF drive motor is rotated in a forward direction.

FIG. 10 is a diagram showing a configuration in the vicinity of a first document guide member and a second document guide member when an ADF drive motor is rotated in a reverse direction.

FIG. 11 is a diagram showing a situation in which a document once taken into the apparatus in the second reading mode reaches the vicinity of a glass window.

FIG. 12 is a diagram showing a case where a document is stored in a document storage unit and also set on a document tray.

FIG. 13 is a block diagram showing a configuration of an image data processing unit of the image reading device.

FIG. 14 is a flowchart showing a document attribute determination process.

FIG. 15 is a diagram showing a lookup table created for an element [1,1] = 299 of an arithmetic matrix.

FIG. 16 is a schematic diagram of a conventional image reading device.

FIG. 17 is an enlarged view of an ADF unit of a conventional image reading device.

FIG. 18 is a schematic diagram of an optical system of a conventional image reading device.

[Explanation of symbols]

 1 Image Reading Device Main Body 2a Original Glass 2b Glass Window 3 Carriage 4 Supporting Member 5 Shaft 6 Drive Wire 7 Drive Pulley 8 Driven Pulley 9 Drive Motor 10 Driven Pulley Supporting Member 11 Energizing Means 12 ADF Unit 13 Original Tray 14 Discharge Tray 15 Document detection sensor 16 Paper feed roller 17 Reverse roller 18 Document edge detection sensor 19 Conveyance roller 20 Guide roller 21 Guide roller 22 Document ejection detection sensor 23 Ejection roller 24 Lamp 25 Aperture 26 Reflection mirror 27 Color image sensor 28 Imaging lens 29 Conveyance Passage switching means 30 Shaft 31 First original guide member 32 Second original guide member 33, 34 Shaft 35 Original storage section 36 Original (first original) 37 First step 38 Second step 39 Power transmission member 40 Sha Shift 41 Cam 42 Spring clutch 43 Power transmission lever 44 Energizing member 45 Joint member 46 Stopper 47 Second manuscript 48 Amplifier 49 A / D converter 50 Shading calculator 51 Image degree converter 52 Image memory 53 CPU 54 DMA 55 Interface Department

Claims (12)

[Claims] 1. A document tray on which a document is placed, a reading unit for reading the document, and a conveying unit for conveying the document in a forward direction and a reverse direction, the conveying unit in the first reading mode. The document on the document tray is conveyed in the forward direction and guided to the reading unit, and after the reading by the reading unit is finished, the document is further conveyed in the forward direction and discharged,
An image reading apparatus which conveys a document in a forward direction and guides it to the reading unit in the second reading mode, and conveys the document in a reverse direction after the reading by the reading unit is completed. 2. An original storing means for storing an original, and the second
2. The image reading apparatus according to claim 1, further comprising a conveyance path switching unit that guides a document conveyed in the opposite direction by the conveyance unit to the document storage unit in the reading mode. 3. The conveyance path switching means does not prevent the conveyance of the original when the conveyance is performed in the forward direction, and regulates the conveyance direction of the original when the conveyance is performed in the reverse direction. The image reading device according to claim 2, wherein 4. A conveyance path from the document tray to the reading means and a conveyance path from the document storage means to the reading means have a common portion, and are arranged in the common portion to detect a document. 4. The image reading apparatus according to claim 2, further comprising a document detecting unit. 5. The first original detecting means detects the leading edge of the original conveyed in the forward direction by the conveying means in the first and second reading modes to generate the original reading start timing. 5. The image reading apparatus according to claim 4, wherein in the second reading mode, a state that there is a document is output when the document is stored in the document storing means. 6. A reading start instructing means for instructing the start of reading of an original, a second original detecting means for detecting the presence or absence of an original in the original tray, and an original in one of the original tray and the original storing means. The selecting means further includes a selecting means for selecting, and the selecting means detects the state of the presence of the original by both the first and second original detecting means when the reading start instructing means gives an instruction to start reading the original. 6. The image reading apparatus according to claim 4, wherein, in this case, the original in the original storing means is selected, and the conveying means conveys the original selected by the selecting means. 7. The conveying means conveys an original once in the reverse direction when the original in the original storing means is selected by the selecting means, and the first original detecting means sets the state of no original. 7. The image reading apparatus according to claim 6, wherein the document is conveyed in the forward direction and guided to the reading unit when detected. 8. The apparatus further comprises a plurality of document guide members arranged in the vicinity of the reading means, and a displacement means for displacing the plurality of guide members in accordance with a document transport direction by the transport means. The image reading device according to any one of claims 1 to 7. 9. The apparatus further comprises designation means for designating a reading range and reading resolution for the original, and reading start instructing means for instructing to start reading the original, and the conveying means is instructed to start reading by the reading start instructing means. Then, the document is conveyed at the maximum speed until the beginning of the reading range designated by the designating means reaches a predetermined position, and thereafter, at the speed set according to the reading resolution designated by the designating means. 9. The image reading apparatus according to claim 1, wherein the original is conveyed at a reduced speed. 10. The apparatus further comprises designating means for designating a reading range for the original, and the conveying means, at the maximum speed, reads the original which has finished reading the reading range designated by the designating means in the first reading mode. The image reading apparatus according to claim 1, wherein the image reading apparatus conveys the sheet in a forward direction and discharges it. 11. The apparatus further comprises designating means for designating a reading range for the original, and the conveying means, at the maximum speed, of the original which has finished reading the reading range designated by the designating means in the second reading mode. The image reading apparatus according to claim 1, wherein the image reading apparatus conveys the image in a reverse direction. 12. In the third reading mode, the conveying means conveys the original on the original tray in the forward direction and guides it to the reading means, and after the reading by the reading means, conveys the original in the reverse direction. Stored in the document storage means,
3. The image reading apparatus according to claim 2, further comprising a determination unit that determines the attribute of the document based on the output of the reading unit in the third reading mode.