JP2002237926A - Image reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce foreign matters, such as dust deposited on an original, from depositing on the surface of contact glass. SOLUTION: The image reader, provided with a read unit 20 that is placed on an original carrying path between carrying rollers 5 and 6 carrying a sheet original 8 and applies exposure scanning to the carried original 8 to read image information and with a backup roller 4 that carries the original, while depressing the original 8 onto the read unit 20 in a way of close contact, is provided with a guide member 21, made of a dielectric material, that is placed on the upper- stream carrying path with respect to that of the read unit 20 and a part of which is in slide contact with the original 8 to charge electric charges to the original 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus used in a copying machine, a facsimile, a scanner, or the like for reading an image of a document while transporting the document.

[0002]

2. Description of the Related Art An image reading apparatus used in an image forming apparatus such as a copying machine, a facsimile, a scanner or the like irradiates light from a light source onto an image surface of a document, and reflects the reflected light on a CCD.
It is configured to read by a reading unit such as. In such an image reading apparatus, an original is placed on an image mounting table made of contact glass or the like with the image side down, and the image reading unit provided below the image mounting table is moved to move the original. There are a reading format and a reading format in which a document is transported by a document transport unit and the moving document is read by the image reading unit fixed in the transport path.

[0003]

In the latter document reading type image reading apparatus, the document reading section of the image reading unit is provided with a contact glass.
Original paper dust and dust may adhere to the contact glass. If you leave such dirt as it is,
These dirt and dust may be continuously read by the image reading unit. Therefore, if the read information is converted into image data, the image data includes continuous white or black stripe data due to dirt or dust. When reproducing an image from this image data, white or black stripes appear. For example, there is a problem that image quality is deteriorated.

The present invention has been made in view of such a demand, and an object of the present invention is to reduce foreign substances such as dust adhered to an original from adhering to the surface of a contact glass and to prevent the above-mentioned problems. It is to be.

[0005]

In order to achieve the above object, a first means is a conveying means for conveying a sheet-shaped document, and the document which is located in a document conveying path by the conveying means and is conveyed. And a backup roller that conveys the original while pressing the original so that the original comes in close contact with the reading unit. And a guide member made of a dielectric material, which is provided in the transport path on the upstream side in the direction and partially charges the original by slidingly contacting the original.

[0006] To achieve the above object, the second means is as follows:
The first means is characterized by further comprising blowing means for blowing an air current from the guide member toward the reading means.

[0007] To achieve the above object, a third means is as follows.
The first or second means is characterized in that the guide member is formed of a film-like elastic resin member extending in a direction perpendicular to the document conveying direction.

[0008] To achieve the above object, a fourth means is as follows.
In the image reading device based on the same premise as the first means,
A voltage applying means for applying a predetermined voltage to the backup roller, and a rubbing member for removing a substance attached to the surface of the backup roller are provided, and the backup roller is electrically conductive so as to be charged by the voltage applying means. It is characterized by doing.

In order to achieve the above object, a fifth means is as follows.
An image reading apparatus based on the same premise as the first means, further comprising a rubbing member that presses against the backup roller, wherein the backup roller is at least partially provided so that static electricity is generated on the surface thereof by friction with the rubbing member. And an insulating material.

[0010] To achieve the above object, the sixth means comprises:
In the first to fifth means, the transporting means includes transport rollers upstream and downstream in the transport direction with the reading means interposed therebetween, and the transport speed of the upstream transport roller is lower than the transport speed of the downstream transport roller. Is set as follows.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the same reference numbers are assigned to the units that can be regarded as equivalent,
Duplicate description will be omitted as appropriate.

First, a first embodiment of the present invention shown in FIG. 1 will be described. The reading unit 20 includes a light source 2 that irradiates the sheet-shaped original 8 with light through the contact glass 1, a self-focus lens array 3 that collects reflected light when the light from the light source 2 is irradiated, A CCD 7 for imaging light from the self-focus lens array 3. The transport path A of the document 8 is composed of a transport path formed by the guide plates 11 and 15, a transport path between the contact glass 1 and the backup roller 4, and a transport path formed by the guide plates 13 and 16. I have. Guide plate 1
In the middle of the transport path formed by the guide rollers 13 and 16, a document transport means including the transport roller 5 and the driven roller 9 is provided. Document transport means 10 are provided. The transport rollers 5 and 6 are driven to rotate by driving means (not shown). With this configuration, the sheet document 8 is illuminated by the light source 2 while being conveyed at a constant speed by rotating the conveying rollers 5 and 6 in the direction of the arrow by a driving unit (not shown), and the reflected light is transmitted to the selfoc lens. A backup roller 4 that can take out an image signal as an electric signal when formed on the CCD 7 by the array 3 is provided so as to be swingable through an arm around a fulcrum shaft, not shown, and is usually provided on the contact glass 1. It is elastically pressed. The peripheral surface of the backup roller 4 is white, and is driven to rotate in the direction of the arrow by a driving unit (not shown). Further, a flange roller (not shown) having a diameter slightly larger than the diameter of the backup roller 4 shown is provided at both axial ends of the backup roller 4 outside the range in which the original can be passed. 1
A slight gap is provided between the backup roller 4 and the contact glass 1 to prevent the contact between the backup roller 4 and the contact glass 1 to cause damage.

A guide plate 11, which is located on the paper feeding side of the original 8,
A guide member 21 made of a film-like elastic resin member made of a dielectric material is provided at a downstream side of the document 15 so as to be inclined downward toward the downstream direction of the document 8. The downstream end of the guide member 21 projects toward the backup roller 4 with respect to the transport path A, and
The document reading position. The guide member 21 slides the document 8 against the guide member 21 and charges the surface of the document, and then passes through the document reading unit.

According to this configuration, foreign matter such as dust adhering to the reading surface side of the original 8 is attracted to the original 8, and does not adhere to the contact glass 1, and
It is possible to prevent image abnormalities such as white streaks and black streaks that occur when adhering matter stagnates on the reading line. The downstream end of the guide member 21 protrudes toward the backup roller 4 with respect to the transport path A, and guides to a position where the guide member 21 does not touch the document reading position. While being pressed by the guide member 21 and pressed against the backup roller 4, the corrugation or the like of the document is corrected, and the reading surface of the document 8 is stabilized.

The conveying speed of the conveying rollers 5 and 6 is set slightly earlier for the conveying roller 6 on the downstream side so that the original 8 is stretched between the conveying rollers 5 and 6. As a result, the original 8 can be kept in contact with the backup roller 4 at all times.

In the second embodiment of the present invention shown in FIG. 2, the structure is the same as that of the first embodiment except that a blower is provided on the guide member 21. The blower means includes a fan 31, a duct 32 for blowing the exhaust airflow from the fan 31 to the guide member 21, and a dustproof filter 33 provided between the fan 31 and the duct 32. As a result, the exhaust airflow generated by the fan 31 is blown onto the guide member 21 by the duct 32, thereby forcibly blowing off foreign matter adhering to the contact glass 1 such as dust. Note that the exhaust airflow from the fan 31 is sent to the duct 32 via the dustproof filter 33, whereby the cleaned exhaust airflow can be sent to the guide member 21.

In the first and second embodiments described above,
Dust and the like adhering to the original 8 on the surface in contact with the contact glass 1 are removed.
In the fourth embodiment, the foreign matter such as dust adhered to the backup roller is also removed.

That is, in the third embodiment of the present invention shown in FIG. 3, the backup roller 41 is made of a conductive material, is rotatably supported by the insulating bearing 17, and has a voltage application means 42. , A predetermined voltage is applied. The backup roller 41 is provided with a rubbing member 43 so that an upper end thereof comes into contact with the surface of the backup roller 41 in order to scrape off the attached matter 22 attached to the surface of the backup roller 41 from the document 8. The lower end side of the rubbing member 43 is disposed inside the container 44. Similarly to the first embodiment, the backup roller 41 has a white peripheral surface, and has flange rollers at both ends in the axial direction, and is swingable and normally elastically pressed against the contact glass 1. It is provided so that.

By applying a predetermined voltage to the backup roller 41 by the voltage applying means 42, the original 8 in contact with the backup roller 41 is electrostatically charged,
Attachment 22 such as dust attached to the reading surface side of original 8
Is attracted to the original 8 and the contact glass 1
The streaks are prevented from adhering to the image, and the image abnormality of the white stripes and the black stripes caused by the stagnation on the reading line can be prevented. The surface opposite to the reading surface of the original 8 and the guide plate 15
The backup roller 4 adheres to the top and is carried by the original 8.
1 is scraped off by a rubbing member 23 arranged to be in contact with the outer peripheral surface of the backup roller 41, and the scraped-off deposit 22 is removed from the container 24.
Is stored in. Further, since the attached matter 22 dropped from the backup roller 41 by the rubbing member 23 is stored in the container 24, the attached matter 22 does not scatter inside the reading device.

In the fourth embodiment of the present invention shown in FIG. 4, the surface of the backup roller 51 is made of an insulating resin, and the outer surface of the backup roller 51 is pressed by the upper edge to scrape off the deposit 22. Rubbing member 23
Are arranged, and static electricity is generated on the surface of the backup roller 51 by the rubbing between the backup roller 51 and the rubbing member 23. Due to the static electricity, the attached matter 22 attached to the original 8 can be attracted to the original 8, and the attached matter 22 on the original 8 can be prevented from attaching to the contact glass 1. Further, similarly to the above-described third embodiment, the attached matter 22 attached to the backup roller 51 is scraped off by the rubbing member 23 and stored in the container 24.

[0021]

As is apparent from the above description, according to the first aspect of the present invention, the original slides on the guide member and charges the original surface, thereby causing the original to be read on the reading surface side. The attached matter such as the attached dust can be adsorbed on the document. As a result, dust and the like do not adhere to the surface of the reading unit that is in contact with the document, and it is possible to prevent white streaks and black streaks that occur when the stuck matter stagnates on the reading line. Also, by sliding the document on the guide member, the waving of the document is forced by the guide member, so that the out-of-focus state can be improved.

According to the second aspect of the present invention, since the air blowing means for blowing the air current from the guide member toward the reading means is provided, the air flow from the blowing means is blown to the reading means, so that the reading in contact with the original is performed. Dust or the like adhering to the surface of the means can be forcibly blown off, and the occurrence of abnormalities in the image due to white streaks or black streaks caused by the adhering matter can be more reliably prevented.

According to the third aspect of the present invention, since the guide member is formed of a film-like elastic resin member extending in a direction orthogonal to the document conveying direction, it can correspond to the document thickness.

According to the fourth aspect of the present invention, the backup roller is charged by the voltage applying means, so that the adhering matter adhering to the reading surface side of the document is attracted to the document, and the reading means in contact with the document. Is not adhered to the surface, and the image abnormality of the white streak and the black streak caused by the stagnant matter on the reading line can be prevented.

According to the fifth aspect of the present invention, with a very simple structure in which at least a part of the backup roller is made of an insulating material, static electricity is generated on the surface of the backup roller by sliding friction between the backup roller and the sliding member. The attached material is attracted to the document by the static electricity, and the attached material is prevented from adhering to the surface of the reading means in contact with the document, so that an image free from abnormal images is reliably provided by a simple configuration. be able to.

According to the sixth aspect of the present invention, since the linear velocity ratio of the transport roller is higher on the downstream side than on the upstream side, the original can be securely brought into close contact with the backup roller.
The effect due to static electricity can be enhanced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a schematic configuration of an image reading device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a schematic configuration of an image reading device according to a second embodiment of the present invention.

FIG. 3 is a diagram illustrating a schematic configuration of an image reading device according to a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a schematic configuration of an image reading device according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Contact glass 2 Light source 3 Selfoclenth array 4,41,51 Backup roller 5,6 Conveyance roller 7 CCD 8 Document 11,13,15,16 Guide plate 17 Bearing 20 Reading unit 21 Guide member 42 Voltage applying means 43 Scraping Element

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/00 108 H04N 1/12 Z F-term (Reference) 2H076 AA58 BA24 BA27 BA28 BA68 BA97 3F049 AA01 CA01 DA12 EA13 LA02 LB02 3F101 AA09 AB12 FB14 FB15 FC03 FD02 FD04 LA02 LA05 LA11 LB02 5C062 AA05 AB17 AB32 AC02 AD06 5C072 AA01 BA17 NA01

Claims (6)

[Claims] A transport unit configured to transport a sheet-shaped document;
Reading means for reading image information by exposing and scanning the document to be conveyed, which is located in a document conveying path by the conveying means, and a backup for conveying the document while pressing the document so as to come in close contact with the reading means An image reading apparatus comprising: a roller; and a guide member having a dielectric portion that slides on the original and charges the original by charging the original. The guide member is disposed on a transport path upstream of the reading unit in the original transport direction. Image reading device. 2. The image reading apparatus according to claim 1, further comprising a blowing unit that blows an air current from the guide member toward the reading unit. 3. The image reading apparatus according to claim 1, wherein the guide member is formed of a film-shaped elastic resin member extending in a direction perpendicular to a direction in which the document is transported. 4. A conveying means for conveying a sheet-shaped document,
Reading means for reading image information by exposing and scanning the document to be conveyed, which is located in a document conveying path by the conveying means, and a backup for conveying the document while pressing the document so as to come in close contact with the reading means An image reading apparatus comprising: a roller; a voltage application unit configured to apply a predetermined voltage to the backup roller; and a rubbing member configured to remove a substance attached to a surface of the backup roller. An image reading apparatus characterized in that it is made conductive so as to be charged by said voltage applying means. 5. A conveying means for conveying a sheet-shaped document,
Reading means for reading image information by exposing and scanning the document to be conveyed, which is located in a document conveying path by the conveying means, and a backup for conveying the document while pressing the document so as to come in close contact with the reading means An image reading apparatus comprising: a roller; and a rubbing member that presses against the backup roller, wherein the backup roller has an insulating material on at least a part thereof so that static electricity is generated on a surface by friction with the rubbing member. An image reading device comprising: 6. The conveyance means includes conveyance rollers upstream and downstream in the conveyance direction with the reading means interposed therebetween, and is set so that the conveyance speed of the upstream conveyance roller is lower than the conveyance speed of the downstream conveyance roller. The image reading device according to claim 1, wherein the image reading device is configured to: