JPH09233268A - Original reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve both accurate shading correction and highly accurate carriage of an original and to perform highly accurate read relating to an original reader for reading images while carrying the original. SOLUTION: This original reader is provided with a carriage part 14 for carrying and passing through the original to a read position on a target glass 15, a read part 16 for reading original images by irradiating the read position with light and fetching the reflected light and a flexible white reference sheet 26 in press contact through the original on the read position. At the time of performing the shading correction by the white surface of the white reference sheet 26, the posture of the read part 16 is changed by swinging a bracket 31 to the carrying direction of the original and the read position of the target glass 15 is covered larger than the time of reading the original by the white reference sheet 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document reading device, and more particularly to a document reading device for reading an image while conveying a document.

[0002]

2. Description of the Related Art Conventionally, there is known a document reading device which reads a document image by irradiating a document passing through a reading position with light and capturing the reflected light. In this document reading device, the document reading device is pressed against the reading position. There is a method in which shading correction is performed by the white surface of a white reference sheet that brings the original into close contact with the reading position.

In this type of document reading apparatus, a pair of rollers, which are pressed against each other and one of which is driven to rotate and the other of which is driven to rotate, are provided on the upstream side and the downstream side of the reading position in the document conveying direction. There is one that clamps and conveys the document, and when closing / opening the document conveyance path, one side of the roller pair is held by a pressure plate rotatably supported by the main body of the device, or a white reference sheet is attached. There is.

[0004]

In order to accurately perform shading correction, such an original reading apparatus prevents the white reference sheet from capturing reflected light from other than the reading position as in the case of the original at the time of reading. There is a need to. However, in the conventional document reading apparatus, since the pair of rollers support both end sides, a pressure distribution in the document width direction is generated in the pressure contact force, and the pressure plate itself bends when held by the pressure plate. For this reason, a part of the white reference sheet floats above the reading position and a gap is formed between the white reference sheet and the reading position, so that the reflected light reflected at a position other than the reading position is captured, and the shading correction can be accurately performed. Without this, the reading accuracy will decrease. Also,
There is also a problem that the original also floats above the reading position.

In order to solve this problem, for example, in the document reading apparatus disclosed in Japanese Patent Laid-Open No. 4-266259, a white reference sheet is provided by providing a sponge material under pressure on the back side of the white reference sheet. Also, the original is pressed against the scanning position and is in close contact. Also, for example,
In the document reading apparatus disclosed in Japanese Patent Laid-Open No. 5-80614, the white reference sheet is folded back to the side opposite to the reading position so that the repulsive force presses the white reference sheet to the reading position so that it can be brought into close contact with the reading position.

However, in the former document reading device,
Since the white reference sheet is pressed against the entire reading position, accurate shading correction can be performed, but when a non-rigid original such as thin paper is conveyed, the load (conveyance resistance) due to the white reference sheet is large, so it is conveyed. There is a problem that the accuracy is reduced and a jam occurs. Note that this problem is not limited to thin paper, and may similarly occur due to an increase in conveyance resistance depending on the use environment.

In the latter document reading apparatus, the pressure applied to the reading position changes depending on the degree of bending of the white reference sheet and the assembly thereof, so that the white reference sheet can be appropriately pressed against the reading position. There are things you can't do. Therefore, there has been a problem that high-precision processing and assembly are required. Further, since the pressure to be pressed against the white reference sheet changes with time, the shading correction cannot be accurately performed if the reading position cannot be covered sufficiently. Further, there is a problem that the original cannot be brought into close contact with the reading position sufficiently, or conversely, the conveyance resistance becomes large.

Therefore, an object of the present invention is to provide an original reading device capable of achieving both accurate shading correction and highly accurate document feeding, and highly accurate reading.

[0009]

To achieve the above object, the invention according to claim 1 conveys an original to a reading position and passes it through, and irradiates the reading position with light to capture the reflected light. A document reading apparatus comprising: a reading unit that reads a document image by means of the document reading apparatus; and a posture control unit that changes a posture of the reading unit.

According to the first aspect of the present invention, the posture of the reading means is changed and the relative position of the reading position (plane) with respect to the apparatus main body is changed. Therefore, it is possible to arbitrarily set the relative positional relationship between the reading position of the reading means and the document or the apparatus main body component according to the reading conditions such as the drive mode and the document type. According to a second aspect of the invention, in addition to the configuration of the first aspect of the invention, a flexible white reference member that is pressed against the reading position of the reading unit via the document, and a white surface of the white reference member are provided. Correction means for performing shading correction by reflected light from the posture control means,
It is characterized in that the posture is changed so as to cover the reading position more largely during shading correction than the press contact area where the white reference member is pressed against the reading position during reading.

According to the second aspect of the present invention, the attitude of the reading means is changed so that the area covering the reading position during shading correction is larger than the pressing area of the white reference member on the reading position during reading. Therefore, at the time of reading, the white reference member does not increase the transport resistance only by adhering the reading area of the original to the reading position. There is no capture.

The invention according to claim 3 is the invention according to claim 1 or 2.
In addition to the configuration of the invention described in (1), the attitude control means changes the attitude of the reading means based on the detection information of the document conveyed by the conveying means. In the invention according to the third aspect, the attitude of the reading means is changed based on the detection information of the original, for example, the position of the original to be conveyed, the type of the original, and the like. Therefore, for example, when the shading correction is performed before the reading mode is executed, the relative position with respect to the white reference member is changed according to the position of the document to perform the highly accurate shading correction in which the reading position is covered with the white reference member. After that, it is possible to carry out document transport without an increase in transport resistance. Further, when reading a strong original, the white reference member may be brought into close contact with the reading position.

According to a fourth aspect of the invention, in addition to the configuration of the invention according to any one of the first to third aspects, a switching means for switching the transmission destination of the driving force according to the driving direction of the driving source of the conveying means. Is provided, the conveying means conveys the document by the driving force of a driving source that drives in one direction of forward and reverse driving, and the attitude control means drives the driving source in the other direction of forward and backward driving, and the driving force transmitted by the switching means. The posture of the reading means is changed by.

According to the fourth aspect of the present invention, the transmission destination of the driving force of the driving source is switched according to the forward / reverse driving, the original is conveyed by one of the normal driving and the reverse driving of the driving force, and the other is driven. The attitude of the reading means is changed. Therefore, the drive source can be commonly used, and it is not necessary to provide a special drive source.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. 1 to 5 show a first image reading apparatus according to the present invention.
It is a figure which shows embodiment, This embodiment respond | corresponds to invention of Claims 1-3. First, the configuration will be described.

In FIG. 1 and FIG. 2, reference numeral 10 denotes an original reading device mounted on a copying machine or a facsimile machine. The original reading device 10 separates the originals stacked on the original table 11 one by one. Separation unit 12 for feeding and feeding (passing) the fed document to the reading position for discharging tray 13
And a reading section (reading section) that irradiates the original passing through the target glass (contact glass) 15 located at the reading position with light and captures the reflected light to read the original image. 16 and a sensor 17 that detects the leading edge of the original on the original table 11 to detect that an unprocessed original remains, and the leading edge of the original before the scanning unit 16 to detect that the original to be read has been conveyed. Sensor
The control unit (not shown) receives sensor information (position detection information and the like) from a sensor group including 18 and controls driving of each unit.

The separating unit 12 is composed of a feed roller 21 that is driven to rotate in the document conveying direction and sends the document to the downstream side, and a separation pad 22 that comes into pressure contact with the feed roller 21 with a predetermined pressure contact force. Are set to be larger between the originals, between the originals and the separation pad 22, and between the originals and the feed roller 21, so that the lowermost original is separated and fed to the conveying unit 14. The separation method by the separation unit 12 is not limited to the separation pad 22, and may be another method such as a separation roller that rotates in the opposite direction.

The transport unit 14 is driven to rotate in the document transport direction on the upstream side and the downstream side of the reading unit 16 and transports the document to the downstream side. The transport roller 23 is pressed against each of the transport rollers 23 with a predetermined pressure contact force. Then, the conveying roller 23 and the opposed roller 24 (roller pair) sandwich the original between the pressure contact portions of the conveying roller 23 and the opposed roller 24 and convey the conveyed original to the discharge tray 13.

In the drive system of the separating section 12 and the conveying section 14, the idler gear transmits the driving force of a motor (driving source) (not shown) to the feed roller 21 and the conveying roller 23 to rotate them. Further, the separation pad 22 and the opposed roller 24 define (form) a document transport path together with the target glass 15 and rotatably support one of the left and right outer sides in the drawing so that the transport path can be closed / opened. Is supported by a pressure plate 25, the separation pad 22 is rotatably supported on the upstream side, and is pressed against the feed roller 21 by its own weight.
The opposed roller 24 is supported by the pressure plate 25 so as to be pressed against the transfer roller 23 with a predetermined pressing force when the transfer path is defined.

A white reference sheet (white reference member) 26 having a white surface and flexibility is attached to the pressure plate 25 together with the spacer 27 so as to be in pressure contact with the target glass 15. At the time of reading, the white reference sheet 26 is pressed against the upper surface of the target glass 15 through a document conveyed by the conveyance roller 23 and the opposite roller 24 with a pressure contact force that does not hinder the conveyance so that the document is brought into close contact with the target glass 15 and its floating is prevented. In addition, a white surface that is in contact with the reading position of the target glass 15 is used as a white reference during the shading correction described later. The transport roller 23 and the opposed roller 24 are arranged so that the tangent line of the pressure contact portion is the same as or intersects with the upper surface of the target glass 15 at the time of reading, and the positional relationship of the transported document from the upper surface of the target glass 15 also results. It is set not to float.

The reading unit 16 emits light in the main scanning direction (width direction) of the original or the white reference sheet 26 through the target glass 15, and the main scanning direction in which the reflected light is captured and photoelectrically converted. A plurality of photoelectric conversion elements arranged in the
Is a so-called contact sensor composed of and, the photoelectric conversion element 29 captures the reflected light of the light emitted from the light source 28 or reads the image, and is reflected by the white surface of the white reference sheet 26 before the reading is started. So-called shading correction is performed with the reflected light. In this shading correction, the light source 28 is turned on and the white reference of the white reference sheet 26 is used as a reference when the control section receives the detection information of the document front end by the sensor 18 and the conveyance of the document is temporarily stopped. Reading Computes a correction value for correcting the output at the time of reading. Then, at the time of reading a document, the read output is corrected and calculated, so that even if there are variations in the light source 28 and the photoelectric conversion element 29, deterioration due to changes over time, etc., reading is performed with a constant image (density) according to the reading performance. To be able to That is, the control unit constitutes the correction means.

The reading unit 16 is fixed to the bracket 31 with screws 32 on both sides in the width direction of the document to be conveyed.
The bracket 31 has a rotating shaft 33 supported by the main body of the apparatus and a reading unit 16
Is held so that it can be swung in the document conveying direction. The bracket 31 is pulled by a spring 34 on the upstream side in the document transport direction and is pulled by a solenoid 35 on the downstream side. When the bracket 31 is not pulled by the solenoid 35, the bracket 31 is projected downward as shown in FIG. When the target glass 15 is abutted against the present portion 36 and is held at a position where the target glass 15 substantially coincides with the tangent line of the transport roller 23 and the facing roller 24 (the posture is maintained), and the solenoid 35 pulls the target glass 15, the target glass 15 is moved as shown in FIG.
As shown in FIG.
The target glass 15 that is abutted against and is held at a position that substantially coincides with the attachment surface of the white reference sheet 26 attached to the pressure plate 25.

Here, the white reference sheet 26 originally covers the upper surface of the target glass 15 in a range where the photoelectric conversion element 29 does not take in the reflected light from the portion that does not correspond to the reading position during shading correction, and the original document is read during reading. It suffices to make pressure contact with the reading position via. However, since the pressure plate 25 pivotally supports the opposing roller 24 outward in the width direction of the original so that the pressure contact force with the conveying roller 23 becomes predetermined, a pressure distribution occurs in the width direction and the pressure distribution corresponds to the pressure distribution. The pressure plate 25 itself also bends near the center of the document width. Therefore, the white reference sheet 26 is directly attached to the pressure plate 25,
When the original is brought into close contact with the target glass 15 by utilizing the elasticity of 26, there arises a problem that the degree of close contact becomes uneven. From this, the white reference sheet 26 is replaced by the pressure plate 25.
In general, when it is directly attached to the sheet, the white reference sheet 26 needs to have a large contact area, which increases transport resistance. Therefore, in the present embodiment, as shown in FIG. 3, the white reference sheet 26 corresponds to the bending of the pressure plate 25 (the pressure distribution of the transport roller 23 and the counter roller 24) in the vicinity of the center on the downstream side in the document transport direction. Is attached to the pressure plate 25 via a spacer 27 formed to have a width L as a width L, and the attachment surface (attachment surface) of the pressure plate 25 is formed so as to intersect with the target glass 15 when the white reference sheet 26 is formed. The spacer 27 is bent according to the shape of the spacer 27 so that the boundary contacting the target glass 15 is linearly pressed and brought into uniform contact. The thickness of the spacer 27 may be changed in the width direction of the document in accordance with the bending of the pressure plate 25, or the material may be changed in the width direction. Further, the shape of the mounting surface of the pressure plate 25 may be changed.

Then, when the reading unit 16 is in a position to abut against the lower abutting unit 36 shown in FIG. 4, the white reference sheet 26 is brought into close contact with the target glass 15 in an area necessary for reading, and the reading unit 16 makes The target glass 15 can be largely covered so as not to take in light from the outside in the posture of hitting the upper abutting portion 37 shown in FIG. 5 (when shading is corrected). Therefore, the area pressed against the target glass 15 at the time of reading need not be considered for shading correction, and can be set small.

Next, the operation will be described together with the document reading operation. First, when the sensor 17 detects a document placed on the document table 11 and presses a start key (not shown), when there are a plurality of documents, the bottom document is the feed roller 21 and the separation pad 22. Separated and fed by
It is delivered to the upstream conveying roller 23 and the opposing roller 24. Next, when the sensor 18 detects the leading edge of the document which is conveyed further downstream by the conveyance roller 23 and the opposed roller 24, the conveyance is stopped and the solenoid 35 is turned on.
As a result, the bracket 31 is swung (rotated), the reading unit 16 is placed in the posture shown in FIG. 5, and the white reference sheet 26 is held at a position that also largely covers the upstream side of the reading position of the target glass 15, and shading correction is performed. To be executed.

At this time, since the white reference sheet 26 largely covers the reading position of the target glass 15, the photoelectric conversion element 29 does not take in the reflected light from the white reference sheet 26 or the like other than the reading position. Therefore, there is no difference in the output waveform obtained by reading the white color, accurate shading correction can be performed, and the image quality is not deteriorated.

Next, when the solenoid 34 is turned off and the load is released, the bracket 31 is swung by the spring 34 and the reading unit 16 is placed in the posture shown in FIG. 4 so that the white reference sheet 26 is at the reading position of the target glass 15. Is held in the position where it is pressed. After that, the conveyance of the original by the conveying roller 23 and the opposing roller 24 is restarted, the original is conveyed at a predetermined speed while being pressed against the reading position of the target glass 15 by the white reference sheet 26, and the conveying roller 23 on the downstream side and The paper is delivered to the opposite roller 24 and carried out to the paper discharge tray 13. Simultaneously with the transportation of the document, the reading unit 16 captures the reflected light from the document by the photoelectric conversion element 29 in synchronization with the transportation and converts the document image into an electrical signal (output).

At this time, since the original document is only pressed against the reading position on the target glass 15 by the white reference sheet 26 and is brought into close contact therewith, the conveyance resistance is not increased (the spacer 27
(Transfer resistance is smaller than when not using) Even if the paper is weak, the tip is the target glass 15 and white reference sheet.
There is no possibility that a jam will occur without being inserted between 26 and 26, and even if the jam does not occur, the read image will not be stretched without the predetermined transport speed.

As described above, in this embodiment, when the shading correction is performed, the posture of the reading unit 16 is swung (changed) in the document conveyance direction, and the white reference sheet 26 causes the reading position on the target glass 15 to be larger than that at the time of reading the document. Since it covers a large area (up to the outside of the reading position that captures the reflected light during reading),
The photoelectric conversion element 29 does not capture the reflected light from other than the portion corresponding to the reading position of the white reference sheet 26 or the like, and the shading correction can be accurately performed.
When the original after the shading correction is conveyed, the reading unit 16 is swung in the opposite direction so that the white reference sheet 26 presses the reading position on the target glass 15 so that the original is conveyed with a small conveying resistance. Therefore, the document can be conveyed with high accuracy. As a result, the original can be conveyed regardless of the paper quality and the image can be read with high image quality.

Further, since the reading section 16 is swung based on the sensor information of the sensor 18 for detecting the position of the document, the shading correction can be performed for each reading. next,
6 and 7 are views showing a second embodiment of the image reading apparatus according to the present invention, and this embodiment corresponds to the invention described in claim 4. Since the present embodiment has substantially the same configuration as the above-described embodiment, the same reference numerals are given to the same configurations and only the characteristic portions will be described.

In both figures, reference numeral 40 denotes a driving force transmitting mechanism, and the transmitting mechanism 40 swings a bracket 41 for supporting the reading section 16 and a conveying system for conveying the originals of the separating section 14 and the conveying section 16. A motor (driving source) (not shown) can be commonly used as a driving source of the system. The transmission mechanism 40 includes a rotating shaft 42 of the motor and an oscillating gear (switching means) 43.
Meshes with each other and swings in response to the forward and reverse rotations to switch the drive force transmission path.
While engaging the idler gear 44 that meshes with the 21 to transmit the driving force to drive the transport system, the bracket is used during reverse rotation.
The idler gear train 46, which meshes with the sector gear 41a of 41, meshes with the idler gear train 46 to transmit the driving force and change the posture of the reading unit 16.
The driving force from the feed roller 21 to the driving roller 23 is transmitted via the idler gear 45.

The bracket 41 is pulled leftward in the figure by a spring 47, and the feed roller 21 is read during reading.
Further, the idler gear train 46 becomes free to transmit the driving force of the motor to the transport roller 23 to transport the document, and the idler gear train 46 swings due to the elastic force of the spring 47 to move the reading unit 16 to the state described in the above embodiment. While holding against the lower abutting portion 36 at the position shown in the figure, at the time of shading correction, the reading portion 16 is moved to the posture shown in FIG. The upper abutting portion 37 is abutted and held at the position. At this time, since the bracket 41 is biased by the spring 46, the sector gear 41a can be meshed with the idler gear train 46 again. To swing the bracket 41, the motor may be rotated in the reverse direction at the timing when the solenoid 35 is driven in the above embodiment.

The transmission mechanism 40 may be mounted between opposing side plates provided on one side of the pressure plate 25, or a transport system and a swing system may be separately mounted on both side plates.
When it is attached to the side plates on both sides, it is sufficient to form a gear portion on both sides of the feed roller 21 to transmit the driving force. Also,
Not only the rocking gear 43, but a one-way clutch may be interposed in each of the transport system and the rocking system to transmit the driving force in accordance with the driving direction.

As described above, in the present embodiment, the bracket for changing the posture of the reading unit 16 by commonly using the motor for driving the conveying system of the separating unit 14 and the conveying unit 16 and reversely driving the same.
Since 41 is swung, it is not necessary to specially provide a drive source for swinging bracket 41, and this embodiment can be configured without increasing the cost.

[0035]

According to the invention described in claim 1, since the position of the reading position (face) relative to the apparatus main body can be changed by changing the posture of the reading means, the reading of the driving mode, the document type, etc. It is possible to arbitrarily change the relative positional relationship with respect to the document or the apparatus main body parts according to the conditions. According to the second aspect of the invention, since the positional relationship of the reading means with respect to the white reference member can be changed at the time of shading correction and the reading position can be largely covered by the white reference member, the original document is read by the white reference member during reading. The conveyance resistance can be closely attached to the reading position without increasing the conveyance resistance, and the white reference member can largely cover the reading position during shading correction to prevent extra light from being taken in. According to the third aspect of the present invention,
Since the posture of the reading unit is changed based on the position of the document being conveyed, the type of the document, and the like, the posture of the reading unit is changed at the time of shading correction immediately before the start of reading the document, and the reading position is largely covered by the white reference member. It is possible,
It is also possible to change the degree of contact between the white reference member and the reading position depending on the original.

Therefore, at the time of reading, the white reference member allows the area required for reading the original to be brought into close contact with the reading position and at the same time the original can be conveyed without increasing the conveyance resistance. During the correction, the white reference member largely covers the reading position to prevent extra light from being taken in, and the correction can be performed with high accuracy. As a result, the original can be conveyed regardless of the paper quality and the image can be read with high image quality.

Further, the positional relationship with the reading position of the reading means can be adjusted according to the reading conditions such as the driving mode and the document type, and the degree of contact can be changed. According to the invention described in claim 4, the original is conveyed by the driving force of one of the driving sources according to the forward and reverse driving of the driving source, and the posture of the reading unit is changed by the driving force of the other side. It does not need to be specially provided for common use, and the cost does not increase.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic overall configuration of a first embodiment of a document reading apparatus according to the present invention, and is a partially sectional conceptual diagram thereof.

FIG. 2 is a partially enlarged view showing a main part thereof.

FIG. 3 is a plan view showing a member to be attached together with the white reference member.

FIG. 4 is a state diagram showing a posture of the reading means at the time of reading a document.

FIG. 5 is a state diagram showing a posture of the reading unit at the time of shading correction.

FIG. 6 is a diagram showing a configuration of a main part of a second embodiment of a document reading apparatus according to the present invention, which is a partially enlarged cross-sectional view thereof.

FIG. 7 is a conceptual configuration diagram showing a mechanism for switching the transmission destination of the driving force.

[Explanation of symbols]

 10 Image reading device 12 Separation unit 14 Conveying unit (conveying unit) 15 Target glass (Reading position) 16 Reading unit (Reading unit) 26 White reference sheet (White reference member) 27 Spacer 28 Light source 29 Photoelectric conversion element 31, 41 Bracket 33 Rotating shafts 34, 46 Spring 35 Solenoid 40 Transmission mechanism 41a Sector gear 42 Swing gear (switching means)

Claims (4)

[Claims] 1. A document reading apparatus comprising: a feeding unit that feeds a document to a reading position and passes the reading unit; and a reading unit that reads a document image by irradiating the reading position with light and capturing the reflected light. A document reading apparatus comprising a posture control unit that changes a posture of the reading unit. 2. A flexible white reference member that comes into pressure contact with the reading position of the reading unit through a document, and a correction unit that performs shading correction by light reflected from the white surface of the white reference member. 2. The original document according to claim 1, wherein the attitude control unit changes the attitude so as to cover the reading position when shading correction is larger than a press contact area where the white reference member is pressed against the reading position during reading. Reader. 3. The document reading apparatus according to claim 1, wherein the attitude control unit changes the attitude of the reading unit based on detection information of the document conveyed by the conveying unit. 4. A switching means is provided for switching the transmission destination of the driving force according to the driving direction of the driving source of the conveying means, and the conveying means is configured to drive the original by the driving force of the driving source which drives in one direction of forward and reverse driving. 2. The carrying means, wherein the attitude control means drives the drive source in the other direction of forward and reverse driving to change the attitude of the reading means by the driving force transmitted by the switching means.
4. The document reading device according to any one of 3 to 3.