JPH03186540A - Image reading-out device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image reading device suitably implemented in, for example, an electrophotographic device, which reads and exposes an image of a document while pressing the document against a transparent plate with a roller and conveying the document.

2. Description of the Related Art In an electrophotographic apparatus such as a copying machine, for example, in order to read an original image and form an electrostatic latent image, the original is exposed to light and the original image is formed on a photoreceptor. At this time, the original is conveyed by pressing it against a transparent plate such as a glass plate using rollers, and the conveyed original is irradiated with light from a light source placed on the other surface side of the transparent plate, and the image of the original is read from the reflected light. .

FIG. 5 is a front view showing the preparation of the exposure conveyance roller 50 and the transparent plate 53 for exposing the original as described above. The conveyance roller 50 is rotatably supported by bearings 54 and 55 and is disposed in close contact with the glass plate 53 over its entire axial length in order to press and convey the document along the transparent plate 53. be done.

The document, which is conveyed as the conveyance roller 50 rotates while being pinched between the conveyance roller 50 and the transparent plate 53, is transported by a light source and a reflection light (not shown) arranged on the opposite side of the conveyance roller 50 with respect to the transparent plate 53. An exposure means including a mirror or the like irradiates light to read and expose the original image.

Problems to be Solved by the Invention The conveying roller 50 can
In order to convey the original in close contact with the transparent plate 53,
The total length WR in the axial direction is the maximum width W of the document to be transported.
□It is set slightly longer than one. Therefore, the maximum width W
, AX, the conveyance roller 50 is driven to rotate while being in direct contact with the transparent plate 53 at both ends in the axial direction, for example.

The transport roller 50 is made of NfJ, which has a high coefficient of friction with the original, such as rubber, so that the original can be transported with sufficient holding force between the transport roller 50 and the transparent plate 53 without slipping on the transport roller 50. Therefore, when such a conveyance roller 50 is rotated while in contact with the transparent plate 53, its driving resistance increases. As a result, most of the power to the conveying roller 50 is consumed to resist the frictional force between the conveying roller 50 and the transparent plate 53. In such a configuration, each time the conveyance roller 50 and the transparent plate 53 slip, the conveyance speed of the document fluctuates and the document is not conveyed at a predetermined speed. Image expansion/contraction occurs along the direction corresponding to .

An object of the present invention is to solve the above-mentioned technical problems, to be able to read an image of a document while transporting the document at a predetermined speed, regardless of the size of the document to be read, and An object of the present invention is to provide an image reading device capable of reading a homogeneous image.

Means for Solving the Problems The present invention comprises: a transparent plate that guides a document along one surface; a conveyance roller that presses and conveys the document against the surface of the transparent plate; In the image reading device, the conveyance roller has an outer diameter larger than the remaining area over an area less than the minimum width of the original to be read. The image reading device is characterized in that it has a large diameter portion formed therein, and an inclined portion whose outer diameter changes to a smaller diameter as it approaches a smaller diameter portion at an axial end of the large diameter portion.

Function: In the image reading device of the present invention, a document whose image is to be read is guided along one surface of a transparent plate. At this time, the conveyance roller presses the document against the surface of the transparent plate and conveys it. A reading means is disposed on the other surface side of the transparent plate, and reads an image of the document conveyed by the conveyance roller through the transparent plate by exposing it to light.

According to the present invention, the transport roller has a large diameter portion for pressing the document to be read against the transparent plate, which extends over an area less than the minimum width of the document and has a larger outer diameter than the remaining area. . Further, a small diameter portion having an outer diameter smaller than the large diameter portion is formed at the axial end of the conveyance roller, and an inclined portion whose outer diameter changes from the large diameter portion to the small diameter portion is provided. As a result, even if the width of the document to be read is a predetermined minimum width, the conveyance roller is pressed against the surface of the transparent plate through the document over its entire width in the axial direction.

In this way, regardless of the size of the document, the conveyance roller is not rotated while being in direct contact with the transparent plate when conveying the document, so the change in friction coefficient between the conveyance roller and the transparent plate This prevents uneven rotation of the conveying roller from occurring, and does not affect the image read by the reading means on the document.

Furthermore, even if the transport roller is not transporting a document, or even if the width of the document to be transported extends between the large diameter part and the small diameter part of the transport roller, there is a gap between the large diameter part and the small diameter part of the transport roller. Since the slanted portion is formed, the light for exposing the original is irradiated onto a portion where the large diameter portion and the small diameter portion suddenly change step-like in the diametrical direction of the conveyance roller, making it difficult to read the document. When the document image is read by the means, it will not be read as a shadow caused by the amount of light reflected by the large diameter portion and the small diameter portion of the conveyance roller.

Embodiment 1 [:A is the document feeding device 4 which is an embodiment of the present invention.
1 is a simplified cross-sectional view showing the basic configuration of 0. The document supply device 40 is used, for example, in a copying machine 42 shown in FIG. 3, which will be described later.

A document feeding device 40 and a pressing plate 49 are provided at the top of the main body 41 of the copying machine 42 . A first transparent plate 64 and a second transparent plate 65 provided in the document supply device 40 constitute a first reading position W61 and a second reading position 62, respectively.

Further, regarding the pressing plate 49, a third transparent plate 66 as a document table is formed on the pressed surface of the main body 41, and a third transparent plate 66 is formed at the third reading position 6.
3. A manuscript image such as a bound book is presented to this third reading position 63 and exposed.

Referring to FIG. 1, a plurality of sheets of originals having the same size and arranged in anti-digital order are placed on the placing member 11 of the original supplying device 40, with the original surface of the first page facing downward. 11 are placed facing the The document stacked on the mounting member 11 has its end surface blown out by the air blowing from the exhaust duct 105 disposed on the right side thereof, and then the paper feeding means disposed above the document tray is blown away. (2) The documents are taken out one by one starting from the topmost document, and are fed to the conveyance path 67 by the feed roller 43.

The paper feeding means 12 includes an endless belt 107 wound around rollers 60a and 60b, and a duct 12a that opens toward the original document on the inner circumference side of the belt 107. A plurality of suction holes are formed in the belt 107 in a scattered manner, and a vacuum suction device (not shown) is connected to the duct 12a. As a result, the document Di can be fed to the conveyance path 67 while being attracted to the outer peripheral surface of the belt 107 as the document Di is rotated by the rollers 60a and 60b. The exhaust duct 105 is connected to, for example, an induction fan, and when paper is fed, air is blown onto the downstream end surface of the original document in the paper feeding direction to prevent double feeding.

The conveyance path 67 consists of a pair of guide members and a plurality of rollers 44, 45, 46, each pair of which is provided along the conveyance direction, and transports the fed document Di between the exposure conveyance roller 5 and the first roller.
and the transparent plate 64. Here, at the exit on the first transparent plate 64 side of the conveyance path 67, a pair of first lugi rollers 4 are provided.
7 is provided. The rotation shaft of the first Lugi roller 47 includes
A power transmission means is connected via a clutch CLTI (not shown). The timing for transporting the original Di to the first transparent plate 64 is controlled by the rotation/stopping control of the first lugi roller 47 based on the connection/disconnection control of the clutch CLTI.

The original Di is transferred to the first transparent plate 6 by the exposure conveyance roller 5.
4, the document image on one surface is presented to the first reading position 61. Next, the conveyance direction of the original Di is reversed by the reversing means 134, and then the document Di is conveyed between the exposure conveyance roller 6 and the second transparent plate 65 by the second registration roller 48.

In the reversing means 106, the document Di from the first reading position 61 is transferred from the conveyance path 108 formed by the pair of guide members and the pair of conveyance rollers 74 and 75 provided along the conveyance direction via the switching claw 103. and is introduced into the conveyance path 68. The conveyance path 68 is provided with a reversing roller 76 that can rotate in forward and reverse directions. The document Di conveyed to the conveyance path 68 is conveyed to the conveyance path 109 by the reversal of the rotational direction of the reversing roller 76 and the IgJ replacement claw 103 . The document Di guided to the conveyance path 109 is conveyed to the second registration roller 48 by the conveyance roller 100.

A power transmission means is connected to the rotating shaft of the second registration roller 48 via a clutch CLT2 (not shown).

The timing for transporting the original Di to the second transparent plate 65 is controlled by controlling the rotation/stopping of the second registration roller 48 through the connection/disconnection control of the clutch CLT2. The document Di pressed against the second transparent plate 65 by the exposure conveyance roller 6 has its conveyance direction reversed in advance by the reversing means 134, and the document image on the other surface is presented to the second reading position 62. be done.

The document Di for which the presentation of the document images on both surfaces has been completed is carried out on a conveyance path 7 formed by a pair of guide members and a pair of conveyance rollers 101 and 102 provided along the conveyance direction.
3 and transported to the mounting member 11. The conveyed document Di is stored at the bottom of the document tray stored on the placement member 11 and returned by a storage conveyance roller 104 provided close to the storage side end of the placement member 11 .

FIG. 2 is a front view of the exposure conveyance roller 5 and the first transparent plate 64. The exposure conveyance roller 5 is connected to the document supply device 4
It is rotatably supported on the body of No. 0 by bearings 58 and 59.

The exposure conveyance roller 5 has a large-diameter portion 37 formed in the center in the axial direction, which extends over an area smaller than the minimum width WMIN of the document to be conveyed and has a larger outer diameter than the remaining area. Small diameter portions 38 are formed at both ends of the large diameter portion 37 in the axial direction.

Further, from the large diameter portion 37 to the small diameter portion 38, a truncated conical inclined portion 39 whose outer diameter continuously changes to a smaller diameter is formed.

The total axial width W, 1 of the exposure conveyance roller 5, which is made up of the large diameter portion 37, the small diameter portion 38, and the inclined portion 39, is set to be greater than or equal to the maximum width WMA8 of the document to be conveyed. Further, the outer circumferential surface of the exposure conveyance roller 5 is selected to have a white color that can sufficiently reflect the light source irradiated during exposure. The structures of the exposure conveyance roller 6 and the second transparent plate 65 are also similar.

The material of the exposure conveyance rollers 5 and 6 has a relatively high coefficient of friction against the document so that the document is conveyed in close contact with the document without slipping, and when the rollers themselves are exposed to light, the material has a relatively high coefficient of friction against the document. A white material that can sufficiently reflect light and whose temperature rises little due to light irradiation, such as room temperature curing silicone rubber (RTV), is selected.

Referring again to FIG. 3, an exposure means 76 is provided inside the copying machine main body 41, and the exposure means 76 is located at the first and second reading positions 61, 62.
．． Alternatively, the document image presented at the third reading position 63 is imaged on a right cylindrical photoreceptor 77 having a horizontal rotation axis and rotationally driven in the direction of arrow R13, and the charging corona discharger 78 An electrostatic latent image corresponding to the original image is formed on the surface of the photoreceptor 77 which has been charged in advance. In the exposure means 76, the first moving body 7 includes six light sources and a reflecting mirror 70.
1 is displaced to the first to third reading positions 61 to 63, respectively, and irradiates the presented document with light, and the reflected light is transmitted to the reflecting mirrors 79, 80, zoom lens 81, and reflecting mirror of the second moving body 72 The image is formed on the photoreceptor 77 via 82.

The electrostatic latent image formed on the photoreceptor 77 is developed into a toner image by a developing device 83, and is transferred onto one surface of the recording paper P by a transfer corona discharger 84. The recording paper P is stored in the paper feed cassette 85 in advance, and
It is transported by a transport means 87 including registration rollers 86 and guided to a transfer area 88 . Third registration roller 86
A power transmission means is connected to the rotating shaft of the engine via a clutch CLT3 (not shown). By performing the connection/disconnection control of the clutch CLT3 in conjunction with the control of the clutches CLTI and CLT2 of the first or second registration rollers 47 and 48, the third registration roller The timing of conveyance of the recording paper P by 86 can be adjusted. The recording paper P onto which the toner image has been transferred by the transfer corona discharger 84 is guided from the conveying means 89 to the fixing device 90 and is fixed thereon.

After fixing, the conveying direction of the recording paper P is reversed by the direction changing means 91, and the recording paper P is temporarily stored in the intermediate storage means 93 via the conveyance path 92. The recording paper P in the intermediate storage means 93 is guided again to the transfer area 88 by the conveyance means 94 and the third registration roller 86, and the toner image is transferred to the other surface of the recording paper P. The recording paper P on which the transfer has been completed is discharged to a tray 96 outside the machine via a conveyance means 89, a fixing device 90, and a conveyance path 95.

Here, when one surface of the document is read and exposed with the photoreceptor 77, the movable body 71 is positioned directly below the first reading position 61, and when the other surface is read and exposed,
Note that in the case of a document such as a book, the first moving body 71 is located directly below the second reading position W62.
is horizontally scanned and exposed. At this time, the second moving body 72 is also driven to run in the same direction as the first moving body 71 at half the scanning speed. In this way, both the front and back sides of the original document are copied onto both the front and back sides of the corresponding recording paper P. For example, recording sheets P having mutually different sizes are selectively conveyed to the transfer area 88 from the paper feed cassettes 85, 97, 98, and 99.

FIG. 4 is a block diagram showing the electrical configuration of the copying machine 42. As shown in FIG. In the configuration of the copying machine 42, the exposure conveyance roller 5
, 6 and other motors M1. M2. ... etc. are connected to the motor drive circuit 110. It is provided between the rollers and the motor, and controls the drive timing thereof to synchronize the timing of conveyance between the document Di conveyed within the document supply device 40 and the recording paper P conveyed within the main body 41. Clutch CLTI, CL
T2. . . . are connected to the clutch drive circuit 111. Electromagnetic solenoid 5OL1 that operates switching claws, etc.
5OL2. . . . are connected to the solenoid drive circuit 112. These drive circuits 110 to 112 are connected to an interface circuit 113.

The interface circuit 113 includes a DC power supply 114, various detectors for detecting the conveyance status of the original and the recording paper P, a drive circuit 115 for driving the exposure means 76, and an input from an operation panel 116 provided on the copying machine main body 41. Operation key 1
19, a display drive circuit 117 for driving display means 118 of operation panel 116, and the like are connected.

The ink face circuit 113 is connected to a processing circuit 120 realized by a microcomputer or the like, and sends a detection signal from the detector to the processing circuit 120, and also controls the various drives according to control signals from the processing circuit 120. Controls circuits 110-112, 115, 117. The processing circuit 120 includes a read-only memory (ROM).
51 is connected to a random access memory (RAM>52), and according to a control program stored in advance in the memory 51, the processing circuit 120 cooperates with the copying If! 42 and document supply device 40 to perform a copying operation. control.

The memory 52 is used, for example, as a calculation area for counters, timers, flags, and the like necessary for controlling copying operations.

The interface circuit 113 also drives the exposure means 76 via the drive circuit 115 to
63 controls the lighting/extinguishing of the light source 69 and the lighting level. Furthermore, the interface circuit 113 sends a signal inputted by the input operation key 119 of the operation panel 116 to the processing circuit 120, and also drives the display means 118 by the display drive circuit 117 to display information regarding the progress of the copying operation and the like. indicate.

Furthermore, the interface circuit 113 includes a selection switch 5SW for selecting a copy mode using the original supply device 40.
I~SSW4 are connected. With this operation,
Make multiple copies from a set of multiple originals! As Mr. r3, we can make single-sided copies from single-sided originals, double-sided copies from single-sided originals,
Various copy modes are selected, such as single-sided copying from a double-sided original, and double-sided copying from a double-sided original.

As explained above, the width W R2 in the axial direction of the large diameter portion 37 that comes into contact with the document, which is divided into the exposure transport rollers 5.6, is
Minimum width W of the document to be transported. 11, the conveyance rollers 5.6 do not come into direct contact with the transparent plates 64.65 during conveyance of the document, regardless of the size of the document.
As a result, the document is conveyed by being pressed against the transparent plate 64.65 by the conveyance rollers 5.6, and the document is conveyed by the conveyance rollers 5.6.
Therefore, the torque applied to the conveying roller 5.6 for conveying the document can be kept constant at a lower level than in the past. In this way, uneven rotation of the conveyance rollers 5 and 6 is suppressed, and the document image is read by conveying the document at a predetermined speed, so that a faithful copy image without expansion or contraction can be formed.

The color tone of the surfaces of the conveyance rollers 5 and 6 is selected to be white enough to reflect light from a light source 69 such as an exposure lamp, and the large diameter portion 37 and the small diameter portion 38 are sloped portions whose diameters continuously change. 39, even if the conveyance rollers 5 and 6 are exposed to light, the conveyance rollers 5 and 6 themselves will not be copied and the three inclined portions will not be formed as shadows on the copied image.

That is, for example, when copying a document having a minimum width W□ onto copy paper P having a maximum width W x s Areas 56, 57 (see FIG. 2) are also exposed. In the background of the document surface to be exposed at this time, the outer diameters of the transport rollers 5 and 6 gradually change continuously from the large diameter portion 37 to the small diameter portion 38 via the three inclined portions. Due to the difference in the amount of reflected light from the portion 39 and the small diameter portion 38, the shadow of the conveyance roller 5.6 may appear on the background at the outer edge in the axial direction of the conveyance rollers 5, 6, and the background at the front and rear edges in the conveyance direction. will not be copied.

In this embodiment, the document is transported by the exposure transport rollers 5 and 6 so that the center line along the widthwise transport direction of the document is aligned with the center position of the exposure transport rollers 5 and 6 in the axial direction. However, one measuring end along the conveyance direction of the document may be aligned with the axial end portions of the exposure conveyance rollers 5 and 6 and conveyed. In such a case, the inclined portion 39 of the exposure conveyance roller 5.6 may be formed at least at the end opposite to the end with which the end of the document is aligned.

In the exposure conveyance rollers 5 and 6 of the above embodiment, the inclined portion 39
was formed into a truncated cone shape in which the outer diameter continuously changes to a small diameter near the axial end, but it is also possible to form it into a step shape with a small diameter change as long as the shadow is not readable during exposure. be.

Further, in the above embodiments, the present invention has been described as the document feeding device 40 provided in the transfer type electrostatic copying machine 42, but the present invention is not limited to an optical system using such an exposure means 76, and for example, a CDD ( The present invention can also be widely applied to a contact type image reading device using a line image sensor consisting of a photoelectric conversion element such as a charge-coupled device.

Effects of the Invention According to the present invention, the conveyance roller that conveys the document whose image is to be read by pressing it against the surface of the transparent plate has a large diameter portion having a width less than the minimum width of the document that comes into contact with the document to be read, and and a small diameter portion at the axial end of the portion, and an inclined portion is formed between the large diameter portion and the small diameter portion.

As a result, when a document to be read is conveyed while being pressed against the transparent plate, the conveying roller does not come into direct contact with the transparent plate without passing through the document. Therefore, expansion and contraction along the conveyance direction in the read image due to a change in the coefficient of friction due to direct contact is prevented.

Furthermore, even if the boundary between the large diameter part and the small diameter part of the conveyance roller is exposed, since the boundary part is formed as an inclined part where the outer diameter changes to a small diameter, shadows may occur due to the difference in the amount of reflected light. This prevents images with .

Therefore, according to the present invention, an image of a document can be read faithfully. In addition, the shadow of the conveyance roller is not read in the background area other than the read document, and the image reading quality is significantly improved.

[Brief explanation of drawings]

FIG. 1 is a simplified sectional view of a document feeding device 40 according to an embodiment of the present invention, FIG. 2 is a front view of an exposure conveyance roller 5, and FIG. A simplified sectional view, FIG. 4 is a block diagram showing the electrical configuration of the copying machine 42, and FIG. 5 is a front view of a conventional exposure conveyance roller 50.

Claims (1)

[Scope of Claims] A transparent plate that guides the document along one surface, a conveyance roller that presses the document against the surface of the transparent plate and conveys it, and a transport roller that is disposed on the other surface of the transparent plate and guides the document through the transparent plate. and a reading means for reading a document image by exposing the document to light, wherein the conveyance roller has a large diameter portion that extends over an area less than the minimum width of the document to be read and has a larger outer diameter than the remaining area. An image reading device characterized by having an inclined portion whose outer diameter changes to a smaller diameter as the large diameter portion becomes a small diameter portion at an axial end thereof.