JPH11266336A - Image reader and image processor provided with the reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a read sensor of an image reader to be hardly affected by the noise caused by static electricity flowing through the path of earth. SOLUTION: This image reader is provided with a sheet placing base 4 that places sheets and is provided in the reader body, sheet carrying means 6, 12 that carry sheets, an image read means 14 that reads an image of a sheet carried by the sheet carrying means, and an earth path E in contact with the sheet to ground the sheet. The shortest distance between the read means 14 and an outer face of the reader body is selected to be at least a minimum distance by which the image read means 14 is not affected by a noise from a noise generating source and an interval Y between the image read means 14 and the earth path E is selected more than the minimum distance.

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 for reading an image on a sheet, such as a multifunction printer, a facsimile, an image scanner, and an image processing apparatus provided with the apparatus.

[0002]

2. Description of the Related Art Conventionally, an image reading apparatus used for a facsimile, a multi-function printer, a scanner or the like mainly includes a reading sensor 14, a pair of conveying rollers 12, 13 and a pair of discharging rollers, as shown in FIG. 1
6, 17; the paper feed / separation unit 5;
And a transport guide 19.

An original P, which is a sheet set on the original mounting table 204, is fed by a paper feed / separation unit 5 to a lower original PB.
The paper is separated and fed one by one from the feeding roller 19, and is fed between the feeding roller pairs 12 and 13 while being guided by the feeding guide 19. further,
The original is read from a pair of transport rollers 12 and 13 by a reading sensor 1.
The paper passes between the paper discharge roller pair 16 and 17 and is discharged. The image on the manuscript is
The sheet is read by the reading sensor 14 when passing through the reading sensor 14 and the white paper pressing plate 15, and is sent to a personal computer, a telephone line, or the like through a path (not shown).

[0004]

However, in the conventional image reading apparatus 200, when the document P is charged with static electricity in the vicinity of the document loading table 204, the double feeding phenomenon, in which the documents are overlapped and sent by sticking to each other, However, there has been a problem that a feeding failure phenomenon or the like occurs in which the original P is stuck to the transport guide 19 and is not smoothly fed.

Therefore, in order to solve the double feeding phenomenon due to charging and the feeding failure phenomenon, the original P
It is necessary to provide static elimination means for eliminating static electricity.

However, in this case, since the vicinity of the original loading table 204 is a place where the user can easily touch, static electricity of a high voltage is likely to fly from the outside such as in a dry winter season, and the static elimination means in the vicinity of the original loading table 204 is used. May fall. In such a case, if the ground path of the static elimination means is provided near the above-described reading sensor 14, the reading sensor can accurately read an image under the influence of noise generated by excessive static electricity flowing through the ground path. May not be possible. Particularly, a recent reading sensor having good sensitivity is easily affected by noise.

Further, in the above-described image processing apparatus equipped with an image reading apparatus for performing image processing, the image reading may be inaccurate or the sheet may not be fed smoothly. In addition, there is a problem that an image formed on a sheet is distorted or a streak is formed in the image, so that a high-quality image cannot be formed.

The image processing apparatus includes a multifunction printer, a facsimile, an image scanner,
There is a copying machine.

[0009] Accordingly, the present invention prevents the static electricity from being charged on a document, thereby preventing the occurrence of a double feeding phenomenon or a feeding failure phenomenon, and the influence of noise generated by static electricity flowing through a reading sensor through a ground path. It is an object of the present invention to provide an image reading apparatus which is hardly affected by an image, and an image processing apparatus provided with this apparatus and which improves the quality of an image formed on a sheet.

[0010]

The above object can be achieved by the following image reading apparatus.

A sheet loading table provided on the apparatus main body for loading sheets, sheet transport means for transporting the sheet, image reading means for reading an image of the sheet transported by the sheet transport means, A ground path for contacting and grounding the sheet, wherein the shortest distance between the reading means and the outer surface of the apparatus body is at least a minimum at which the image reading means is not affected by noise from a noise source. A distance between the image reading unit and the ground path is set to be equal to or longer than the shortest distance.

Further, a grounded conductor is provided between the image reading means and the ground path.

A sheet loading table provided on the apparatus main body for loading sheets; sheet transport means for transporting the sheets; image reading means for reading an image of the sheets transported by the sheet transport means; A ground path for contacting the sheet and grounding the sheet,
When the image reading means is affected by noise from the ground path, a conductor grounded between the reading means and the ground path is provided.

Further, the sheet stacking table is formed of a conductive material to form a part of a ground path.

[0015] The ground path may include a brush formed of a conductive material and contacting the sheet.

Further, the conductor is a metal body to which driving means for operating the sheet conveying means is attached.

The above problem is solved by the following image forming apparatus.

An image reading apparatus according to any one of the above, and an image forming apparatus for forming an image read by the image reading apparatus.

[Operation] When the ground path is provided, the distance between the reading means and the outer surface of the apparatus main body is used as a guide, and the ground path is provided at a distance more than the distance from the image reading means. , And is not affected by noise generated by static electricity flowing through the ground path.

Further, the static electricity charged on the original is grounded by a ground path.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS.

[First Embodiment] An image reading apparatus according to a first embodiment will be described with reference to FIGS.

FIG. 1 is a cross-sectional view of a multi-function printer M which is an example of an image processing apparatus having an image reading section 2 as the image reading apparatus of the first embodiment.

FIG. 2 is a view of the image reading unit shown by a dotted line in FIG.

FIG. 3 is an enlarged view of the image reading section 2 of the multifunction printer of FIG.

A multifunction printer M shown in FIG. 1 includes an image forming unit 1 for forming an image on a print sheet S as a sheet, an image reading unit 2 for reading an image of a document P, and an operation panel for performing a facsimile operation and a copy operation. It is composed of a part 3 and the like.

The configuration of the image forming section 1 as an image forming apparatus will be described.

A plurality of print sheets S can be stacked on the feed tray 301. Feeding unit 3
02 is a feeding tray 301 by a feeding roller 303 or the like.
This unit separates and feeds the upper printing paper S one by one. The process cartridge 304 includes the photosensitive drum 30
5 and process means (charging means, developing means, cleaning means) acting thereon are integrally provided, and are detachable from the printer main body.

The transfer roller 306 transfers the toner image formed on the photosensitive drum 305 to the print paper S passing between the transfer roller 306 and the photosensitive drum 305 facing the transfer roller 306. The fixing unit 307 semi-permanently fixes the toner image on the print paper S to which the toner image has been transferred. The laser scanner unit 308 supplies the photosensitive drum 305 with image information read by the image reading unit 2 or laser light, which is image information sent from a connected computer (not shown) or another multifunction printer. Irradiation forms a latent image. Paper discharge unit 309
Are a discharge roller 310 and a discharge roller 311 facing each other.
And constitutes the discharging means. Discharge paper loading table 31
Reference numeral 2 denotes a stand for receiving the print sheet S discharged by the discharge roller 310 and the discharge rollers 311.

The operation of the image forming section 1 will be described.

When the image forming unit 1 receives a print command, the print sheets S stacked on the feed tray 301 are separated and fed one by one by a feed roller 303, and are separated from the photosensitive drum 305 in the process cartridge 304. The sheet is sent between the transfer roller 306 (nip). The print command is generated, for example, when image information is sent from a personal computer (not shown) or when image information is received via a telephone line as a facsimile. A pit image of image information (laser light) is emitted from the laser scanner unit 308 together with the print command onto the photosensitive drum 305, and a toner image is formed on the photosensitive drum 305 according to the pit image.

The toner image formed on the photosensitive drum 305 is transferred to the printing paper S at the nip between the photosensitive drum 305 and the transfer roller 306. Then, the print paper S to which the toner image has been transferred is sent to the fixing unit 307, and is heated and pressed by the fixing unit 307. As a result, the toner image is semi-permanently fixed on the print sheet S.

The print paper S on which the image has been fixed is sent to a paper discharge unit 309 via a paper inversion guide 313.
The print paper S is supplied to the discharge roller 310 and the discharge rollers 31.
1 and is discharged onto a discharge paper stacking table 312.

Next, the image reading section 2 will be described.

In FIG. 3, the document loading table 4 is capable of loading a plurality of document sheets P. As shown in FIG. 2, the document loading table 4 is formed, for example, in a U-shape by bending a wire, and both ends of the U are inserted into the document loading table holding holes 26 of the main body B. Thereby, it can be attached to and detached from the main body. A leaf spring member 20 is provided in the portion B, and is in contact with the document loading table 4 at a predetermined pressure.
The leaf spring member 20 passes through the back side of the document conveying surface and is connected to a sheet metal member 21 disposed on a side surface of the image reading unit 2. The sheet metal member 21 is connected to a ground G via an earth cord 27. The leaf spring member 20, the sheet metal member 21, and the ground cord 27 form a ground path E of the wire document mounting table 4.

The reading sensor 14 is, for example, a contact sensor or a CCD sensor, and has an approximately rectangular parallelepiped shape having two long sides and two short sides. Here, the long side is in the paper width direction (left-right direction in FIG. 2), and the length is slightly larger than the paper width.

The above-mentioned ground path E is set so as to keep a certain distance from the reading sensor 14. This distance will be described later in detail.

The paper feed / separation unit 5 shown in FIG. 3 includes a paper feed roller 6 made of an elastic member having a high friction coefficient, and a separation friction piece 7 made of an elastic member for separating a plurality of original sheets P one by one. Separation friction piece holding member 8, separation friction piece holding member 8,
Frictional piece urging means 9 for urging the toner in the direction of paper feed roller 6
An arm member 10 for transporting the original P to a nip portion composed of a paper feed roller 6 and a separation friction piece 7;
And an arm member urging means 11 for urging the sheet in the direction of the paper feed roller. The transport rollers 12 and the transport rollers 13
Nips are formed facing each other. A white paper pressing plate 15 is provided at a position facing the reading sensor 14. The discharge roller 16 and the discharge roller 17 face each other to form a nip. The transport roller 13 and the paper discharge roller 17 are urged by roller biasing means 18 in the direction of the opposing transport roller 12 and paper discharge roller 16, respectively. The transport guide 19 serves to introduce the leading end of the document P that has passed through the paper feed / separation unit 5 into the nip of the pair of transport rollers 12 and 13, and reads the leading end of the document P that has passed through the pair of transport rollers 12 and 13 by a sensor 14. And a role of introducing the nip into the nip between the paper holding plate 15 and the white paper holding plate 15.

The operation of the image reading section 2 will be described.

A plurality of originals P loaded on the original loading table 4
Is conveyed by the arm member 10 and the paper feed roller 6, and is formed into a bundle formed in a wedge shape with a tip end projecting downward, and formed by the paper feed roller 6 and the separation friction piece 7. The paper is fed to the nip of the paper / separation unit 5. Of the plurality of original sheets P, those other than the lowermost original sheet PB are blocked by the friction separating pieces 7. As a result,
Only the lowermost document PB is separated by the separating friction piece 7,
The paper is fed downstream by the conveyance force of the paper feed roller 6.

At this time, if there is no charge removing means in the vicinity of the document loading table 4, the documents adhere to each other due to static electricity generated by sliding of the document on the transport path, and a double feeding phenomenon occurs in which the documents are overlapped and fed. . In addition, due to the static electricity, the document P sticks to the document loading table 4, and a paper feeding failure phenomenon in which the document is not fed smoothly occurs. Therefore, by providing the static elimination means, the static electricity can be released to the ground G, and the sticking of the documents and the sticking of the documents to the document loading table 4 can be prevented. As a result, the double feeding phenomenon and the paper feeding failure phenomenon do not occur. In the first embodiment,
The static elimination means is a wire original mounting table itself.

On the other hand, since the vicinity of the document loading table 4 is a place where the user can easily touch, high-voltage static electricity is likely to fly from outside such as in a dry winter season. May fall on a wire platen). Since the static electricity generates noise from the ground path E of the static elimination means, if the ground path E is near the reading sensor 14, the reading sensor 14
Malfunction such as poor image reading. Therefore, it is necessary to keep a certain distance between the ground path E and the reading sensor 14. As shown in FIG.
The distance between the reading sensor 14 and the reading sensor 14 (hereinafter, this distance is referred to as “Y”) is the shortest distance between the reading sensor 14 and the main body outer surface 28 shown in FIG. 1 (hereinafter, this shortest distance is “X”).
) Is set longer. However, a region that is particularly enhanced against noise is excluded from the range of the shortest distance X.

In a general image reading apparatus including the first embodiment, the position of the reading sensor 14 is set so as not to be affected by an external noise source (other than noise from the ground path E). You have set. That is, in the image reading apparatus, even if there is an external noise source at a position apart from the reading sensor 14 by a distance X, the reading sensor 14 does not malfunction. When the external noise is replaced with the noise from the ground path E, the ground path E is located at a position more than the distance X from the reading sensor.
If there is.

When the earth path E is provided, the distance between the reading sensor 14 and the outer surface 28 of the apparatus main body is used as a guide. It is provided at a position where the reading sensor 14 is not affected by noise.

In FIG. 2, the reading sensor 14
Is shorter than the shortest distance X.
Although the side wall appears to be shorter, the side wall seen in the figure is located closer to the right end of the reading sensor 14, and the side wall facing the right end protrudes to the right, and the distance from the right end is the shortest distance X. It is longer.

The image reading apparatus according to the first embodiment includes a sheet feeding / separating unit 5 having a separating function for separating a plurality of originals one by one. Even in an image reading apparatus into which a user inserts a document, a reading sensor may malfunction due to a ground path for discharging static electricity generated when the user continuously inserts a document. Also in this case, the reading sensor can be prevented from malfunctioning by providing the ground path at a position satisfying the above set conditions.

[Advantages of the First Embodiment] Therefore, according to the image reading unit (image reading device) 2 of the first embodiment, when the earth path E is provided, the reading sensor (image reading means) 14 and the device When the ground path is provided at a distance equal to or longer than the reading sensor 14 based on the distance between the outer surface 28 of the main body and the guide, the ground path may naturally be provided at a position where the reading sensor 14 is not affected by noise. it can.

Further, the ground path is connected to the reading sensor 14.
If the sensor is provided at a position where noise is not affected, the reading sensor 14 can accurately read an image without malfunction.

Further, the static electricity charged on the document loading table (sheet loading table) and the document (sheet) is grounded through the ground path, so that the occurrence of the double feeding phenomenon or the feeding failure phenomenon can be prevented.

[Second Embodiment] An image reading section which is an image reading apparatus according to a second embodiment will be described with reference to FIG.

In FIG. 4, the same portions as those in FIGS. 1 to 3 or portions having the same functions are denoted by the same reference numerals as those in FIGS. 1 to 3, and description thereof is omitted. .

The drive motor 22 is a motor for driving the paper feed roller 6, the transport roller 12, the paper discharge roller 16 and the like via a drive gear (not shown), and is mounted on the main body of the image reading section 2 by a mounting plate 23. Have been.

The image reading unit 2A of the second embodiment is
The configuration is characterized in that the earth path E passes through the opposite side of the reading sensor 14 with respect to the motor 22 and the motor mounting plate 23. Ground path E and reading sensor 14
By arranging the motor mounting plate 23 in the vicinity of the portion where the distance is the shortest and providing the auxiliary ground path F, the reading sensor 14 can be more effectively protected from noise.

The reading sensor 14 and the ground path E
By arranging a grounded metal plate in a region where the shortest distance X cannot be obtained between the reading sensor 14 and the outer surface of the main body between the reading sensor 14 and the reading sensor 14, the reading sensor 14 can be protected from noise from the ground path E.

From the opposite viewpoint, the reading sensor 14 can be protected by the sheet metal 23, the distance Y can be reduced, and the image reading section 2A can be downsized.

In FIG. 4, the sheet metal member 21 is farther from the reading sensor 14 than the shortest distance X, but is separated for clarity in the drawing. .

[Advantages of the Second Embodiment] The image reading unit (image reading device) 2A of the second embodiment also prevents malfunction of the reading sensor (image reading means) 14 due to static electricity and charges the original. This can prevent the occurrence of a double feed phenomenon or a paper feeding failure phenomenon.

Further, since a grounded mounting plate (conductor) 21 is provided between the reading sensor 14 and the ground path E, the ground path is provided at a position shorter than the shortest distance X with respect to the reading sensor 14. However, the reading sensor 14 is not adversely affected by noise in the ground path.

Further, the mounting plate 21 allows the ground path to be provided at a position shorter than the shortest distance X with respect to the reading sensor 14, so that the image reading section can be downsized.

[Third Embodiment] An image reading section which is an image reading apparatus according to a third embodiment will be described with reference to FIG.

In the image reading unit 2B, a plurality of originals P are stacked on the original stacking table 104. The paper feed / separation unit 105 includes a paper feed roller 106 made of an elastic member having a high friction coefficient, a separation friction piece 107 made of, for example, an elastic member for separating a plurality of original sheets P one by one, a separation friction piece holding member 108, and , Separation friction piece holding member 1
08 in the direction of the paper feed roller 106. The reading sensor 114 is
The urging means 124 is disposed so as to face the white roller 125.
Is biased toward the white roller 125.

The transport guide 119 has a role to introduce the leading end of the document P that has passed through the paper separating section 105 into a nip formed by the reading sensor 114 and the white roller 125. The plurality of originals P loaded on the original loading table 104 are
Only the uppermost document PT is sent to the downstream side by the feed force of the feed roller 106 by the feed separation unit 105.

The static elimination means in the third embodiment is a static elimination brush 120, which is grounded to the ground G through the conductive member 121 and the earth cord 27. Therefore, the neutralizing brush 120, the conductive member 121, and the ground cord 27 form a ground path E.

When the neutralizing brush 120 contacts and slides on the uppermost document PT, static electricity flows to the ground G,
The amount of static electricity on the document is reduced, so that the double feeding phenomenon and the feeding failure can be prevented.

The ground path E is connected to the read sensor 1
4 is at least the shortest distance X or more. This can prevent malfunction of the reading sensor due to noise.

The image reading apparatus according to the third embodiment has a separating / feeding function for separating a plurality of documents one by one.
An image reading apparatus that has the separation unit 105 but does not have such a mechanism and allows a user to insert a document one by one, even in an image reading apparatus that releases static electricity generated when a user continuously inserts a document, is a ground path. May cause the reading sensor to malfunction. Also in this case, the reading sensor can be prevented from malfunctioning by providing the ground path at a position satisfying the above set conditions.

[Advantage of Third Embodiment] According to the image reading apparatus 200 of the third embodiment, an accurate image reading can be performed while minimizing the malfunction of the reading sensor (image reading means) 114 due to static electricity. As a result, the original can be fed smoothly without static electricity.

Since the multi-function printer M, which is an image processing apparatus, includes the image reading units 2, 2A, and 2B in which the reading sensor does not malfunction due to static electricity, a high-quality image is printed on the printing paper (sheet) S. Can be formed.

[0069]

According to the image reading apparatus of the present invention, when the ground path is provided, the ground path is read by using the distance between the image reading means and the outer surface of the apparatus body as a guide and the distance from the image reading means to the distance or more. If it is provided separately, the ground path can naturally be provided at a position where the image reading means is not affected by noise.

Further, by providing the ground path at a position where the image reading means is not affected by noise, the image reading means can read the image accurately without malfunction.

Furthermore, the static electricity charged on the sheet stacking table and the sheet is grounded through the ground path, so that the occurrence of the double feeding phenomenon or the feeding failure phenomenon can be prevented.

Further, according to the image reading apparatus of the present invention, since the conductor is provided between the image reading means and the earth path, the earth path is provided at a position shorter than the shortest distance from the image reading means. Even reading sensor 1
4 is not adversely affected by noise in the ground path.

Further, the ground path can be provided at a position shorter than the shortest distance X with respect to the image reading means by the conductor, so that the image reading apparatus can be downsized.

Further, since the image processing apparatus is provided with an image reading device in which the reading sensor does not malfunction due to static electricity, a high quality image can be formed on the sheet.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multifunction printer that is an example of an image processing apparatus including an image reading unit that is an image reading apparatus according to a first embodiment.

FIG. 2 is a view of the image reading unit shown by a dotted line in FIG.

FIG. 3 is an enlarged view of the image reading unit of FIG. 1;

FIG. 4 is a diagram illustrating a ground path of an image reading apparatus according to a second embodiment, which corresponds to FIG. 2;

FIG. 5 is a diagram illustrating a ground path of an image reading apparatus according to a third embodiment.

FIG. 6 is a diagram illustrating a conventional image reading apparatus.

[Explanation of symbols]

P Document (sheet) E Ground path F Auxiliary ground path M Multi-function printer (image processing device) S Print paper (sheet) 2, 2A Reading unit (image reading device) 2B Image reading device 4, 104 Metal document loading table ( Sheet loading table, ground path) 5,105 Paper feed / separation unit (sheet conveying means) 14, 114 Reading sensor (image reading means) 21 Sheet metal member (ground path) 22 Drive motor (drive means) 23 Mounting metal plate for drive motor (Electric conductor, metal body) 27 Earth cord (Earth path) 120 Static elimination brush

Claims (7)

[Claims] An image reading unit configured to read an image of a sheet conveyed by the sheet conveying unit; A ground path for contacting a sheet and grounding the sheet, wherein the shortest distance between the reading means and the outer surface of the apparatus body is such that the image reading means is not affected by noise from a noise source. An image reading apparatus wherein at least a minimum distance is set, and an interval between the image reading means and the ground path is set to be equal to or longer than the shortest distance. 2. The image reading apparatus according to claim 1, further comprising a grounded conductor between said image reading means and said ground path. 3. A sheet stacking table provided on an apparatus body by stacking sheets, a sheet conveying unit for conveying the sheet, an image reading unit for reading an image of the sheet conveyed by the sheet conveying unit, A ground path for contacting a sheet to ground the sheet, wherein when the image reading means is affected by noise from the ground path, a conductor grounded between the reading means and the ground path. An image reading device comprising: 4. The image reading apparatus according to claim 1, wherein the sheet stacking table is formed of a conductive material to form a part of a ground path. 5. The image reading apparatus according to claim 1, wherein the ground path includes a brush formed of a conductive material and contacting the sheet. 6. The image reading apparatus according to claim 1, wherein the conductor is a metal body to which a driving unit for operating the sheet conveying unit is attached. 7. An image processing apparatus, comprising: the image reading apparatus according to claim 1; and an image forming apparatus that forms an image read by the image reading apparatus. .