JPH03278070A - Image reader - Google Patents

Abstract

PURPOSE:To evade the deviation of an exposing distance caused by the floating of an original at an exposing position and to resolve the deviation of focal point in exposure by setting the exposing position where slit-exposing is carried out to the upstream side in the carrying direction of the original compared with a pressing position as for the original carried on a transparent plate. CONSTITUTION:The originals D and Di whose original images are read out are guided along one surface of the transparent plate 64. At this time, a carrier roller 5 presses the original on the surface of the transparent plate 64 and carries it. Exposing means 71 and 72 are stopped and disposed on the other surface side of the transparent plate 64 and expose the original images of the originals D, and Di carried by the carrier roller 5 via the transparent plate 64, to optically read out them. The exposing position is set to the upstream side in the carrying direction of the original compared with the pressing position where the carrier roller 5 presses the originals D and Di on the transparent 64. Thus, a part where so-called floating occurs can not be exposed, so that the deviation of the exposing distance of the original at the exposing position, and further, the deviation of the focal point of a read out original image are resolved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to image reading, which is suitably carried out in, for example, an electrophotographic apparatus, in which an original is pressed against a transparent plate by a roller and conveyed, while an image of the original is read and exposed. between the devices.

2. Description of the Related Art For example, in an electrophotographic apparatus such as a copying machine, an electrostatic latent image and a toner image are formed on a photoreceptor in response to an image optically read from an original, and the toner image is transferred to recording paper. By this, the copying operation is realized. As an example of a configuration for optically reading the document image, a sheet-like document is conveyed while being pressed by a conveyance roller or the like along one surface of a transparent plate such as a hard glass plate, and the sheet-like document is conveyed along one surface of a transparent plate such as a hard glass plate. Light is irradiated from a light source of an exposure means that is disposed at a stop, and the original image is read based on the reflected light that is reflected from the original surface via the transparent plate. In some cases, the original is fixedly placed on one surface of a transparent plate, and the image of the original is read by scanning the exposure means.

FIG. 6 is a sectional view showing a simplified configuration of the vicinity of a transparent plate 150 on which a document is exposed to slit light in the prior art. The transparent plate 150 is disposed at the upper part of the copying machine main body 151, and on the front side there is a document feeder 15 that sequentially conveys sheet-like originals to the transparent plate 150, which is a reading position.
2 is arranged.

In the document supply device 152, a conveyance roller 153 is provided vertically above the transparent plate 150.6 Paper is fed from a document storage section (not shown), and a pair of conveyance rollers 15
4, the original d was transported by transport light I#r155.
passes through the gap between the conveyance roller 153 and the transparent plate 150. The document d is transferred to the transparent plate 15 by the transport roller 153 having an outer surface with a relatively large coefficient of friction.
It is conveyed while being pressed to 0. The document d that has passed over the transparent plate 150 is conveyed along a conveyance path 157 by a pair of conveyance rollers 156 and the like, and is stored again in the document storage section, for example. In this way, the document d is sequentially conveyed along one surface side of the transparent plate 150 so that the document image is read.

Exposure means 15 for exposing the transported document d to slit light
Reference numeral 8 is located on the other surface side of the transparent plate 150 and is disposed on the inner side of the copying machine main body 151. Exposure means 158
, a light source 1 consisting of, for example, a halogen lamp, etc.
From 59, irradiation light is irradiated by a reflecting mirror 161 or the like to an exposure position 160 having a predetermined exposure width A across the transported document d. In this way, the original image of the original d passing above the exposure position 160 is sequentially exposed to slit light. The reflected light from the original d due to the exposure is:
An image is formed on a photoreceptor (not shown) through the reflection R162 and a subsequent optical system such as a zoom lens, thereby forming an electrostatic latent image. In this way, the original image is read.

Problems to be Solved by the Invention In the configuration in which the exposure means is arranged as described above, conventionally, when the transport roller 153 transports the document d, the transparent plate 15
0 and the exposure center 16 of the exposure width A
The exposure value 2160 is set so that the values of 3 and 3 coincide with each other.

FIG. 7 is a cross-sectional view of key points for explaining the shape of the document d conveyed with an exposure value W160. In the configuration of the document feeding device 152 as described above, due to spatial considerations, the document d conveyed toward the transparent plate 150 is
0 from diagonally above (upper right side in FIG. 7), and is conveyed along the conveying direction 164 along the one surface side of the first transparent plate 150, and then the conveying roller 15
3 while being pressed against the transparent plate 150. The document d that has passed through the conveyance roller 153 is again conveyed along a conveyance path 157 that smoothly curves obliquely upward (upper left side in FIG. 7) with respect to one surface of the transparent plate 150 due to spatial considerations.

In this way, the document d conveyed toward the curved conveyance path 157 is conveyed without gradually separating from the transparent plate 150 after the pressing position of the conveyance roller 153. In other words, the downstream side of the document d in the transport direction after the pressing position does not come into close contact with the transparent plate 150, and so-called floating occurs due to the elasticity of the document. That is, manuscript d
The area where is conveyed along one surface of the transparent plate 150 is
Entry position 1 where the transparent plate 150 is entered from the conveyance path 155
65 to the pressing position by the conveyance roller 153.

Therefore, regarding the exposure position 160, half of the exposure width A (A/
In the region 2), the floating occurs, and a difference occurs in the exposure distance between the region and the remaining region of the exposure width A, and as a result, the focus shifts. That is, as a result of copying the exposed original image, image deterioration occurs on the recording paper.

Therefore, the quality of the image reading device and even the copying machine deteriorates.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an image reading apparatus that can avoid defocusing of a document image to be optically read and can significantly improve the quality of the document image.

Means for Solving the Problems The present invention conveys an original by pressing it with a conveyance roller along one surface of a transparent plate, and exposes the transparent plate by an exposure means disposed stopping at the other surface side of the transparent plate. In an image reading device that optically reads a document image by exposing the document through a plate, the exposure position where the document image is read by the exposure means with respect to the conveyed document is such that the conveyance roller presses the document against the transparent plate. The image reading device is characterized in that the position is upstream of the pressing position in the document transport direction.

Operation According to the image reading device of the present invention, the original whose image is to be read is guided along one surface of the transparent plate. At this time, the conveyance roller presses the document against the surface of the transparent plate and conveys it. An exposure means is disposed stationary on the other surface side of the transparent plate, and exposes and optically reads the original image of the document conveyed by the conveyance roller through the transparent plate. Regarding the document, the exposure position is set upstream in the document conveyance direction from a pressing position where the conveyance roller presses the document against the transparent plate. Therefore, on the downstream side of the pressing position in the conveyance direction, there is no need to expose a part where so-called floating occurs, so that the deviation in the exposure distance of the original at the exposure position and the defocus of the original image to be read are eliminated. be done.

Therefore, high quality of the original image read by the exposure can be ensured.

Embodiment FIG. 1 is a simplified sectional view showing the basic configuration of a document feeding device 40 installed in a copying machine 42 which is an embodiment of the present invention, and FIG. FIG. Referring to FIGS. 1 and 2, the copying machine 42 and document supply bag! ! The configuration of 40 will be explained.

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 61 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 original documents having the same size and arranged in the order of page number are placed on the placing member 11 of the document supplying device 40 with the original surface of the first page facing downward. It is placed so that it is facing. 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. 12, 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 blows air at the end surface of the document on the downstream side in the paper feeding direction during paper feeding to prevent duplicate conveyance.

The conveyance path 67 is made up of a pair of guide members and a plurality of rollers 44, 45, 46, each pair of which is provided along the conveyance direction. Transport between. Here, a pair of lugi rollers 47 are provided at the exit of the conveyance path 67 on the first transparent plate 64 side. A power transmission means is connected to the rotating shaft of the first roller 47 via a clutch CLTI (not shown). The document Di
The timing of conveyance to the first transparent plate 64 is controlled.

With respect to one surface of the first transparent plate 64, the document Di smoothly enters from diagonally upward (upper right side in FIG.
On the other hand, the front side document image (the upper surface of the document placed on the placement member 11 ) is presented at the first reading position 61 . The document Di conveyed along one surface of the first transparent plate 64 is transported along a conveyance path 10 formed by a pair of guide members and a pair of conveyance rollers 74 and 75 provided along the conveyance direction.
8, the first transparent plate 64 is moved obliquely upward (upper left side in FIG. 1) with respect to one surface of the first transparent plate 64.
It is conveyed while being smoothly separated from the

Next, the conveying direction of the original Di is reversed by the reversing means 106. In the reversing means 106, the first
The original Di from the reading position 61 first passes through the transport path 10.
8 and is introduced into the conveyance path 68 via the switching claw 103. The conveyance path 68 includes a reversing roller 7 that can rotate in forward and reverse directions.
6 is provided. 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 switching pawl 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 of conveyance of the original Di to the second transparent plate 65 is controlled by controlling the rotation/stopping of the second registration roller 48 by controlling the connection/disconnection of the clutch CLT2.

The document Di that has passed through the second registration roller 48 smoothly enters the second transparent plate 65 from diagonally above, and then passes through the conveyance roller 6.
is pressed against the second transparent plate 65 and conveyed. The conveyance direction of the conveyed document Di has been reversed in advance by the reversing means 106, so that the document image on the other surface (the lower surface of the document placed on the placement member 11) is at the second reading position 62. 6 The presentation of the document image on the other surface is completed, and the conveyance roller 10
6, the document Di is guided obliquely upward from the second transparent plate 65 to a transport path 73 formed by a pair of guide members and each pair of transport rollers 101102 provided along the transport direction, It is conveyed while being smoothly separated from the second transparent plate 65. The document Di guided along the conveyance path 73 passes through a storage conveyance roller 104 and a half-moon roller 1 provided close to the storage side end of the placement member 11.
30, 131, etc., the document is stored at the bottom of the document tray stored on the placement member 11 and returned.

Referring to FIG. 2, an exposure means 7 is provided inside the copying machine main body 41.
6 is provided, and the original image presented at the first and second reading positions 61, 62 or the third reading position 63 is
The image is formed on a right cylindrical photoreceptor 77 having a horizontal axis of rotation and rotationally driven in the direction of arrow R13, and an original image is formed on the surface of the photoreceptor 77, which has been charged in advance by a charging corona discharger 78. A corresponding electrostatic latent image is formed. In the exposure means 76, a first moving body 71 including a light source 69 and reflecting mirrors 69a and 70 is displaced to first to third reading positions 61 to 63, respectively. That is, when one surface of the document is read and exposed to light by the photoreceptor 77, the first moving body 71 is stopped and positioned directly below the first reading position 61, and when the other surface is read and exposed, the first moving body 71 is positioned directly below the first reading position 61. It is stopped and located directly below the reading position 62. In addition, in the case of manuscripts such as books, the third
The reading position 63 is horizontally scanned. Each reading position 61-63
Light is irradiated onto the presented document from a light source 69 located at
The reflecting mirror 7 of the second moving body 72 is driven to travel at a scanning speed of
9 and 80, a zoom lens 81, and a reflecting mirror 82, an image is formed on the photoreceptor 77. In this way, each reading device f61~
At 63, the presented original image is exposed and optically read.

FIG. 3 is a sectional view showing a simplified configuration around the first transparent plate 64, and shows one embodiment in which the arrangement of the exposure means 76 when reading an original image at the first reading position 61 is shown. , the irradiation light from the light source 69 is reflected by the reflecting mirror 69a with respect to the document Di being conveyed along one surface of the first transparent plate 64.
An exposure position 21 where slit exposure is performed with an exposure width AO by concentrated irradiation by a camera, etc. is upstream in the transport direction 24 of the original Di from a pressing position 20 where the original Di is pressed against the first transparent plate 64 by the transport roller 5. Set on the side.

FIG. 4 is a cross-sectional view of key points for explaining the shape of the document Di being conveyed to the exposure position 21. As shown in FIG. As described above, the document Di entering the first transparent plate 64 from diagonally above via the conveyance path 67 is conveyed while being pressed against the first transparent plate 64 by the conveyance rollers 65, and is then conveyed toward the conveyance path 108. transported. Therefore, regarding the downstream side of the document Di in the conveyance direction 24 from the pressing position 20 of the document Di that has passed through the conveyance roller 5, the document Di is conveyed to the conveyance path 108 that curves and extends diagonally upward, and due to the elastic force of the document Di. C) A so-called floating occurs. That is, the document Di is placed on the first transparent plate 64.
The area to be transported along one surface of the transport path 6
7 and enters the first transparent plate 64 from the entry position 23 to the pressing position 20. That is, the pressing position 20
This is a predetermined range on the upstream side in the document conveyance direction 24.

Therefore, in this embodiment, the distance hO is within the range and extends from the pressing position 20 toward the upstream side of the conveyance direction
An exposure position 21 is set with the exposure center 22 being at a separated position. In this way, the area where the lifting does not occur is set at the exposure position 2.
Since the original image passing through the scanner 1 is subjected to slit exposure, the exposure distance shift, that is, the focus shift described in the prior art does not occur, and the high quality of the read original image can be ensured. As a result, the image quality of the recording paper on which the original image read in this way is copied as described later does not deteriorate, and high quality is maintained.

In addition, the distance h from the pressing position 20 to the exposure center 22
O may be appropriately selected so that the exposure position 21 having the exposure width AO falls within the range from the approach position 23 to the pressing position 20.

Furthermore, the configuration of the exposure position described above is based on the transport roller 6 and the second
The same applies to the second reading position 62 made of a transparent plate 65.

Referring again to FIG. 2, the reflected light corresponding to the original image read in high quality as described above forms an image, and the electrostatic latent image formed on the photoreceptor 77 is converted into toner by the developing device 83. The image is visualized and transferred to one surface of the recording paper P by the transfer corona discharger 84. The recording paper P is stored in the paper feed cassette 85 in advance, and is transported by a transport means 87 including a pair of third registration rollers 86 to the transfer area 8.
Guided by 8. The rotation axis of the third registration roller 86 includes
A power transmission means is connected 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 transferred from the conveying means 89 to the fixing device 90.
be guided and established.

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. 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. 5 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, a motor Ml rotationally drives a plurality of rollers including the transport rollers 5 and 6.
, M2. ... etc. are connected to the motor drive circuit 110. A clutch is provided between a roller and a motor and controls the drive timing thereof to synchronize the timing of conveyance of the document Di conveyed within the document supply device 40 and the recording paper P conveyed within the main body 41. CLT1. CLT2°, etc. are connected to the clutch drive circuit 111.

Electromagnetic solenoid SQL 15O that operates switching claws, etc.
L2. . . . are connected to the solenoid drive circuit 112. These drive circuits 110 to 112 are connected to an interface circuit 113.

The ink face 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 for an operation panel 116 provided in 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 interface circuit 113 is connected to a processing circuit 120 realized by a microcomputer or the like, and sends the 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 and a random access memory (RAM) 52 are connected, and according to a control program stored in the memory 51 in advance, the processing circuit 120 cooperates with the copying machine 42 and document supply device 40 to control the copying operation. Take 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. Further, the interface circuit 113 sends a signal inputted by the input operation -8-119 on the operation panel 116 to the processing circuit 120, and also sends information regarding the progress of the copying operation etc. to the display means 118 by the display drive circuit I@117. drive and display.

Furthermore, the ink face circuit 113 includes a selection switch 5SW for selecting a copy mode using the original supply device 40.
I-3SW4 is connected. Through this operation, various copy modes can be used to copy multiple copies from a set of multiple originals, such as single-sided copying from a single-sided original, double-sided copying from a single-sided original, single-sided copying from a double-sided original, and double-sided copying from a double-sided original. is selected.

Therefore, according to the above-described embodiment, when the document is conveyed while being smoothly approached to the transparent plate forming the reading position and being pressed by the conveyance roller, the exposure position where the document is exposed to slit light is Since it is set upstream in the conveyance direction from the pressing position where it is pressed,
There is no shift in exposure distance due to floating of the original at the exposure position, and focus shift during exposure can be eliminated. Therefore, the high quality of the read original image is ensured, and the high quality of the copied image on the recording paper corresponding to the original image is maintained without image quality deterioration. Therefore, the quality of a copying machine or the like equipped with the image reading device of this embodiment is significantly improved.

Although the above embodiment has been described in relation to the configuration of a transfer type electrostatic copying machine, this embodiment is not limited to an optical system using such an exposure means 76, and is applicable to, 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 (charge-coupled device).

Effects of the Invention According to the present invention, the exposure position at which slit exposure is performed for the document being conveyed on the transparent plate is set upstream of the pressing position in the conveyance direction of the document, so that floating of the document at the exposure position, etc. As a result, the focus shift during exposure can be eliminated. Therefore, high quality of the read original image can be ensured, and deterioration in the image quality of an image copied onto recording paper based on the original image can be prevented. In this way, the quality of the image reading device is significantly improved.

[Brief explanation of drawings]

FIG. 1 is a simplified sectional view showing the basic configuration of a document feeding device 40 installed in a copying machine 42 which is an embodiment of the present invention, and FIG. 2 is a sectional view showing the simplified configuration of the copying machine 42. 3 is a cross-sectional view showing the structure around the first transparent plate 64, FIG. FIG. 6 is a block diagram showing the electrical configuration of the transparent plate 1 in the prior art.
A sectional view showing the configuration around 50, FIG. 7 is an exposure position 160
FIG. 3 is a cross-sectional view of key points for explaining the shape of a document d being conveyed. 5.6... Conveyance roller, 20... Pressing position, 21.
...Exposure position, 22...Exposure center, 23...Entry position 1.24...Conveyance direction, 40...Document supply device, 4
2... Copying machine, 64.65... Transparent plate, 76...
Exposure means, AO...exposure width, D, Di...original, P
...recording paper, hO...interval

Claims (1)

[Scope of Claims] A document is pressed and conveyed along one surface of the transparent plate by a conveyance roller, and the document is exposed through the transparent plate by an exposure means that is stopped and disposed on the other surface side of the transparent plate. In an image reading device that optically reads a document image by exposing the document to light, an exposure position where the document image is read by the exposure means with respect to the conveyed document is closer to the document than a pressing position where the conveyance roller presses the document against the transparent plate. An image reading device characterized in that the image reading device is located on the upstream side in the conveyance direction.