JP2002232643A - Original feeder and image forming device provided with this feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove dust attached to an image reading position. SOLUTION: An original feeder 2 is provided with a an introduction feeding roller set 6 and an ejection feeding roller pair 10 for feeding the original to the image reading position where the image of an original is read and subsequently ejecting the original, and a reading roller 22 arranged, facing the image reading position 8 across a gap A allowing the original fed by of the introduction feeding roller pair 6 and the ejection feeding roller pair 10 to pass through. The gap A is set about 0.1 mm to about 0.5 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a document feeder for feeding a document to an image reading position for reading an image of the document and discharging the document, and more particularly to a document feeder having a roller for guiding the document so as to face the image reading position. The present invention also relates to an image forming apparatus, such as a copying machine or a printer, which is provided with the document feeder in an apparatus main body and forms an image on a sheet based on image information read by the document feeder.

[0002]

2. Description of the Related Art Conventionally, a document feeder automatically feeds a document to an image reading position of an image reading device for reading an image of the document. The image reading device is often provided on the upper part of the main body of the image forming apparatus.

[0003] The manuscript includes a manuscript in which characters, figures, pictures, and the like are described on a sheet, in addition to a manuscript in which sentences are described. Examples of the sheet include plain paper, cardboard, and a thin resin sheet which is a substitute for plain paper.

The image reading device irradiates a document conveyed on a platen glass with light and reads the document based on reflected light reflected from the document. As an example of a method of reading an image, there is a so-called drift reading method in which a document is read by moving the document over a fixed light source.
Therefore, the document feeder is required to allow the document to pass over the light source, which is the image reading position, in a stable state.

As a method of transporting a document, there is a method of transporting a document by pressing the document against a platen glass with a belt. Further, there is a method in which a roller with a large inertia and having a certain mass, which is charged with static electricity, adsorbs the document by the static electricity and rotates and transports the document. Further, there is a direction in which a roller formed in a hollow shape and having a plurality of holes is sucked by the air in the roller, sucks the document, rotates, and conveys the document.

However, in recent years, with the speeding up of copying by a digital image forming apparatus that combines digital reading and memory storage, a conveyer type document feeder that conveys a document by a belt or a large roller has a belt or the like. The time required to stop a large roller has become long, and it has been difficult to cope with a high-speed copy.

When an image reading device reads an original on which images are formed on both sides, the original feeding device must perform a reverse feeding operation of inverting the original and feeding the original to the image reading position. When performing this reverse feeding operation, the document feeder reverses the document by reversing the belts and rollers, so that it takes time for the belts and rollers and the like to return to a steady conveyance speed after the reverse rotation, and the image It has been difficult to cope with the high-speed formation.

[0008] In addition, the document feeder of the transport system for transporting by the above-mentioned belt or roller is required to be compact as a unit and to reduce the cost.

In addition, when the image reading device is of the flow reading type, it is necessary that the document feeder can stably convey the document without fluttering at the image reading position. For this reason, as shown in FIG.
And a platen guide 24 facing the platen with a gap B therebetween, and a roller 25 rotating in contact with the platen glass 21 as shown in FIG. 9. The original is sent to the platen glass 21 by the pair of introduction rollers 6a and 6b, then the image is read at the image reading position 8, and is discharged by the pair of discharge conveyance rollers 10a and 10b.

[0010]

However, if dust such as paper dust, rubber scum of the conveying roller, or foreign matter adhering to the document adheres or stays on the image reading position 8 of the platen glass 21, the image reading device may Is read as an image, and when the read image is formed on a recording medium by the image forming apparatus, a black stripe is formed on the recording medium, which causes a black stripe problem.

When the platen guide 24 is disposed with a gap B with respect to the platen glass 21 as shown in FIG. 8, the guide 24 is formed of a rigid body, so that the accuracy and warpage of parts may vary. Therefore, it is necessary to widen the gap between the platen glass 21 and the platen guide 24. Therefore, there is a problem that dust easily stays on the platen glass 21.

Further, if the roller 25 is brought into contact with the platen glass 21 as shown in FIG. 9, since there is no gap between the platen glass 21 and the roller 25, dust carried by the document adheres to the platen glass 21. There was something.

An object of the present invention is to provide a document feeder for removing dust attached to an image reading position by using a document to be conveyed, and an image forming apparatus provided with the document feeder in a main body. .

[0014]

In order to achieve the above object, a document feeder according to the present invention comprises: a document feeder / discharge means for feeding the document to an image reading position for reading an image of the document and then discharging the document; Document guide means disposed opposite the image reading position via a gap allowing passage of the document conveyed by the discharge means, wherein the gap is about 0.1 mm to about 0.5 mm.
mm.

The image reading position of the document feeder according to the present invention is a surface of a platen glass through which the document passes by the document feed / discharge means, and the document guide means is provided to the platen via the gap. A rotating member facing the rotating member; and a gap holding member that holds the gap by contacting the platen glass.

The rotator of the document feeder according to the present invention is adapted to rotate at a peripheral speed substantially equal to the transport speed of the document transported by the document feed / discharge means.

According to another aspect of the present invention, there is provided an image forming apparatus comprising: an image reading unit configured to read an image of a document sent by the document feeder; and image information of the document read by the image reading unit. And an image forming means for forming an image on a sheet.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a document feeder according to an embodiment of the present invention and a copying machine provided with this device in a main body will be described with reference to the drawings.

The document feeder can be provided not only in a copying machine but also in a main body of an image forming apparatus such as a printer. Therefore, the equipment provided with the document feeder is not limited to the copying machine. Although the document feeder according to the present embodiment automatically supplies a plurality of documents to the reading position continuously, the document can be supplied one by one by a user. ing. Therefore, the document feeder is not limited to the automatic document feeder.

(Copying Machine) FIG. 1 is a schematic front sectional view of a copying machine (image forming apparatus) 28.

At the upper part of the copying machine main body 1, there is provided a document feeder 2 which conveys a document to an image reading position 8 and discharges the document. The CPU 29 of the control means provided in the main body 1 of the copying machine 28 uses the illumination system 13 according to a control program provided therein to irradiate the mirror 14 with the reflected light obtained by irradiating the original passing through the image reading position 8. By
An image is recorded by projecting the image onto an optical element (CCD or other element) 15 or a photoconductor.

The photosensitive drum (image forming means) 16 includes
Light corresponding to the recorded document image is irradiated to form a latent image. The latent image becomes a toner image by toner supplied from a toner supply device (not shown). Cassette 1
Reference numeral 7 accommodates a recording medium (sheet) S such as paper or a plastic film.

The recording medium S is transferred from the cassette 17 to the photosensitive drum 16 and the transfer device 18 in response to a recording signal from the CPU 29.
Is supplied between The recording medium S is a photosensitive drum 16
Is transferred by the transfer unit 18. Then, the recording medium onto which the toner image has been transferred is
9, the toner image is fixed.

When images are formed on both sides of the recording medium, the recording medium on which one side of the image is fixed by the fixing unit 19 is
After passing through a double-sided path 20 provided on the downstream side of the fixing device 19, it is turned upside down by a switchback conveyance path 32 on the way, and is sent again between the photosensitive drum 16 and the transfer device 18. As a result, the toner image is also transferred to the back surface of the recording medium.
Finally, the toner image is fixed on the recording medium by the fixing device 19 and is discharged to the outside.

(Document Feeding Device) FIG.
FIG. 2 is a schematic front sectional view of FIG. FIG. 3 is a schematic diagram of a main part of the document feeder 2. Referring to FIG.
Represents the original supplied from the original feeder 4 (see FIG. 1).
Introducing / conveying roller pair (document feeding and discharging means) 6a, 6b
Thereby, the guide path is guided in the introduction path (original guide) 7 and is sent to the image reading position 8.

At the image reading position 8, a platen glass 21 is provided. Below the platen glass 21, an image reading unit (image reading means) 33 including the illumination system 13, the mirror 14, and the like is provided.
Above the platen glass 21, a reading roller (document guide means, rotating body) 22 is provided along the direction perpendicular to the document conveyance direction with a gap A between the platen glass 21 and the upper surface. I have.

In FIG. 3, in order to keep the gap A between the platen glass 21 and the reading roller 22 constant, a gap holding ring (document guiding means, a gap holding member) at both ends of the reading roller 22 and in contact with the platen glass 21. 2
6 are provided. The reading roller 22 and the gap holding ring 26 are rotatably connected to the swinging ends of a pair of swinging links 27 (one of which is not shown) rotatably supported at both ends of a shaft 39 of the introduction conveyance driving roller 6a. And coaxially.

The reading roller 22, the gap holding ring 26, the oscillating link 27 and the like constitute a document guide means. The reading roller 22 and the gap holding ring 2
6 may be provided on the fixed member without being provided on the swing link 27. In this case, in order to ensure that the gap holding ring 26 comes into contact with the platen glass 21, it is preferable that the fixing member is provided on the fixing member so as to be able to approach and separate from the platen glass 21 together with the reading roller 22.

On the downstream side of the image reading position 8, there is provided a discharge path 9 bent at a predetermined curvature above the figure, and a jump table 23 positioned at the entrance of the discharge path 9 and guiding the document to the discharge path 9. Is arranged. The discharge path 9 is provided with a pair of discharge conveyance rollers 10a and 10b.

The introduction / conveyance drive roller pair 6 and the discharge / conveyance drive roller pair 10 constitute a document feeding / discharging means.

The drive configuration of each roller of the document feeder 2 will be described with reference to FIGS.

The original feeder 2 drives each roller by an original supply motor M1 and a transport motor M2 which can rotate forward and backward. FIG. 4 is a diagram showing a drive transmission system on the document introduction side of the document supply motor M1. FIG. 5 is a diagram illustrating a drive transmission system on the document discharge side of the transport motor M2.

In FIG. 4, the forward rotation torque of the document supply motor M1 is transmitted from the pulley P1 to the pulley P2 via the timing belt T1 to each roller. The rotational force of the pulley P2 is transmitted in the order of the gear Z1, the gear Z2, and the gear Z3 attached to the drive shaft 34 of the document supply roller 4a. As a result, the document supply roller 4a rotates in a direction for supplying the document.

The drive shaft 34 of the document supply roller 4a is also provided with a pulley P3. The rotational force of the drive shaft 34 is also transmitted to the pickup roller 4b via the timing belt T2 stretched between the pulley P3 and the pulley P4 provided on the shaft 35 of the pickup roller 4b.

One end of a pair of lifting arms 4c, 4c for supporting the pickup roller 4b is attached to the drive shaft 34 of the document supply roller 4a. When the elevation arms 4c, 4c rotate by the rotation of the drive shaft 34 in the direction of supplying the document (forward rotation of the document supply motor M1), the pickup roller 4b descends and comes into contact with the document. When the pickup roller 4b comes in contact with the document, the drive shaft 34 idles with respect to the elevating arm 4c by the spring clutch X and the spring clutch Y.

The registration drive roller 5a has its drive shaft 3
6, a timing belt T3 stretched over a pulley P5 provided on the pulley P6 and a pulley P6 provided coaxially on the pulley P2.
Thus, the motor M1 is not rotated by the action of the one-way clutch OW1 provided in the pulley P5 when the motor M1 is rotating forward.

The reverse rotation force of the document supply motor M1 is transmitted from the pulley P1 to the pulley P2 via the timing belt T1. The rotational force of the pulley P2 is transmitted from a pulley P6 provided coaxially with the pulley P2 to a pulley P5 attached to the drive shaft 36 of the registration drive roller 5a via a timing belt T3. As a result, the registration driving roller 5a rotates in the direction for supplying the original.

At this time, the drive shaft 3 of the original supply roller 4a
4, the reverse rotation force of the document supply motor M1 is also transmitted.
Due to the reverse rotation of the drive shaft 34, the lifting arm 4c rotates counterclockwise to raise the pickup roller 4b. Due to the reverse rotation of the drive shaft 34, the document supply roller 4a also tries to reverse. However, the document supply roller 4a is provided with a one-way clutch OW2 provided inside the document supply roller 4a.
Does not rotate.

The ascending / descending arm 4c comes into contact with a regulating member (not shown) to be restricted in rotation. The drive shaft 34 idles with respect to the lifting arm 4c by the spring clutch Z.

In FIG. 5, the rotational force of the drive motor M2 is controlled by a pulley P provided on a drive shaft 37 of the drive motor M2.
7 to the pulley P8 via the timing belt T4. The rotational force transmitted to the pulley 8 is transmitted from a pulley P9 provided coaxially with the pulley P8 to a timing belt T6.
Is transmitted to the pulley P10 attached to the shaft 38 of the discharge conveyance drive roller 10a. As a result, the discharge conveyance drive roller 10a rotates forward or backward.

Further, the rotational force transmitted to the pulley P10 is transmitted via a timing belt T7 to a pulley P11 attached to the shaft 39 of the introduction / conveyance driving roller 6a. Thereby, the introduction conveyance drive roller 6a also rotates forward or backward.

The rotational force transmitted to the pulley P11 is applied to the pulley P attached to the shaft 39 of the drive roller 6a.
Rotational force is transmitted from 14 via a timing belt T8 to a pulley P15 attached to the shaft 43 of the reading roller 22, so that the reading roller 22 rotates forward or backward.

Further, the rotational force of the transport motor M2 transmitted to the pulley P8 via the timing belt T4 is transmitted from the pulley P12 provided coaxially to the pulley P8 to the shaft 40 of the reversing drive roller 11a via the timing belt T5. Is transmitted to the pulley P13 attached to the pulley. Thus, the reversing drive roller 11a is also rotated forward or backward.

A pressing solenoid 30 is connected to the reversing driven roller 11b as a driving source for separating the reversing roller pair 11 in FIG. The pressure welding solenoid 30 is
When the excitation (ON) is performed, the reversing driven roller 11b is pressed against the reversing drive roller 11a, and when the excitation is released (OFF), the pressing is released. When the excitation of the pressure contact solenoid 30 is released, the reverse driven roller 11b is pulled by a spring (not shown) and separates from the reverse drive roller 11a.

Further, in the transport path for guiding the original,
An empty sensor S1 for detecting that a document is placed on the document placement unit 3, and a registration sensor S for detecting an end of the document conveyed between the feeding unit 4 and the registration roller pair 5;
2. A read sensor S3 provided upstream of the image reading position 8 for detecting the end of the document, and a discharge sensor S4 for detecting the end of the document discharged from the image reading position 8,
Each is provided.

These sensors S1, S2, S3, S4
Is connected to a CPU 29 that controls the driving of the entire apparatus. The CPU 29 controls the rotation of each of the motors M1 and M2 and controls the excitation of the press-contact solenoid 30 based on the detection signals from the sensors.

The document transport operation by the document feeder 2 when an image is formed on one side of the document will be briefly described.

The originals D are placed on the original placing section 3 by the user, separated one by one by the feeding section 4, and sequentially supplied into the original feeder 2. Subsequently, the document D is received by the registration roller pair 5 and temporarily stopped, a loop is formed, and the skew is corrected. The original D whose skew has been corrected is transferred to the introduction path 7 by the start of the registration roller pair 5.
Will be introduced. Then, the original D is transferred to the introduction conveyance roller pair 6.
To the image reading position 8. The manuscript is
By passing through the image reading position 8, an image formed on the surface of the document is read by the image reading unit 33. The document that has passed the image reading position 8 is sent to a discharge path 9 by a pair of discharge conveyance rollers 10 and discharged onto a discharge tray 12.

The operation of transporting a document by the document feeder 2 when an image is formed on both sides of the document will be described briefly.

First, as described above, when the document passes the image reading position 8, an image on one side (front side) is read. Thereafter, the original is conveyed through the discharge path 9 by the discharge conveyance roller pair 10 and is turned upside down by switchback conveyance of the reversing roller pair 11. Then, the inverted document is sent to the registration roller pair 5 again, and the skew is corrected by the registration roller pair 5 in the same manner as when reading the front surface. The skew-corrected manuscript is introduced in the introduction path 7.
Through the image reading position 8 and the front side (in this case, the back side)
The image formed on is read. Finally, the document passes through the discharge path 9 and is discharged onto the discharge tray 12.

As described above, the document feeder 2
Is transported in the direction indicated by arrow C (see FIGS. 6 and 7), and the image reading unit 33
To read the image of the original.

6 and 7, the original D is conveyed in the direction of arrow C to read the image of the original at the reading position 8. As shown in FIG. 22 enters a small gap A between the image reading position 8 and the image reading position 8 on the platen glass 21.
The dust F that has stayed or adhered to the paper is scraped off at the tip and conveyed while being removed from the image reading position 8.

Further, even if the dust adhering to the document itself falls on the platen glass 21, the gap A between the platen glass 21 and the reading roller 22 is narrow as shown in FIG. Contact is carried to the downstream side, and there is almost no stagnation. Thereby, the document feeder 2
Can prevent the platen glass 21 from being stained on the image reading position 8 and reduce the occurrence of black streaks.

In the present invention, the interval of the gap A is from about 0.1 mm to about 0.5 mm. This is because the thickness of the original is about 0.1 mm and the size of ordinary dust is about 0.03 mm to about 0 mm. .4 mm and the original D on the platen glass 21
From about 0.1 mm at which no dust is pressed, to about 0.5 mm (the thickness of the document is about 0.1 mm + the size of the dust is about 0.4 mm) at which the dust F can be carried together with the document.

As a result of experiments conducted by the present inventor, the most preferable gap A is about 0.4 mm (about 0.4 mm in consideration of component tolerance).
3 to about 0.5 mm).

If the gap A is small, the dust D adhered to the original D may adhere to the platen glass 21 on the contrary. Also, a certain gap is required to allow the original to which the dust adheres to pass as it is. Therefore, the above numerical values of about 0.1 mm to about 0.5 mm are optimal numerical values.

Further, at the image reading position 8, the reading roller 22, which does not act as a load when the document enters, can prevent the conveyed document from being lifted up and suppress the fluttering of the document.

As described above, in the document feeder 2 of the present embodiment, the reading roller 22 is disposed at the portion of the image reading section 33 facing the reading side (the platen glass 21), and the platen glass 21 and the reading roller 22 are arranged. Is provided with a gap A, and the gap A is set to about 0.1 mm.
From about 0.5 mm, the reading roller 22
By rotating the document at substantially the same speed as the speed at which the document is transported, the resistance of the document transport is reduced, and the straightness can be controlled with high precision, so that even a small gap can be managed.

Therefore, the document feeder 2 scrapes the dust on the platen glass 21 with the edge of the leading edge of the document D, and makes the reading surface of the document contact the platen glass 21 without fail. Garbage and the like can be eliminated. In addition, since there is a gap, dust can be prevented from adhering to the platen glass 21.

The reading roller 22 is adapted to rotate at the document conveying speed.
It is not necessary to rotate the surface by reducing the friction coefficient of the surface. Further, a circulating belt may be used instead of the reading roller 22. Further, instead of the reading roller 22, a member such as a guide 24 shown in FIG. 7 having a low surface friction coefficient may be provided. Also in this case, the gap between the belt or the guide and the platen glass 21 is about 0.1 mm to about 0.5 mm.
Of course. When the reading roller 22 is not rotated and the guide is provided, the black stripe problem does not occur.

Since the copying machine 28 of the present invention is provided with a document feeder for removing dust adhering to an image reading position, it is possible to obtain accurate image information of a document and to print an accurate image on a recording medium. Can be copied.

[0062]

According to the document feeder of the present invention, the gap between the image reading position and the document guiding means is set to about 0.1 mm to about 0.5 mm. Can be reduced.

Further, since a small gap is formed between the image reading position and the document guiding means, it is possible to suppress fluttering of the document when the document is conveyed, and to reliably pass the document through the image reading device.

[Brief description of the drawings]

FIG. 1 is a schematic front sectional view of a copying machine which is an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic front sectional view of the document feeder according to the embodiment of the present invention.

FIG. 3 is a diagram illustrating a reading roller, which is a main part of the document feeder illustrated in FIG. 2, and a periphery thereof; (A) It is a front view. (B) It is a side view of (a), and is a partially broken view near the end of the reading roller.

FIG. 4 is a diagram illustrating a drive transmission system on a document introduction side of a document supply motor.

FIG. 5 is a diagram illustrating a drive transmission system on a document discharge side of a conveyance motor.

FIG. 6 is a diagram for explaining an operation in a state where dust is removed at the leading end of a document.

FIG. 7 is a diagram for explaining an operation in a state where dust adhering to a document once falls on a platen glass and then adheres to the document again and is discharged.

FIG. 8 is a front view of a main part of a conventional document feeder.

FIG. 9 is a front view of a main part of another conventional document feeder.

[Explanation of symbols]

A gap D document S recording medium (sheet) F dust M1 document supply motor M2 transport motor 1 copier (image forming apparatus) main body 2 document feeder 6 introduction transport roller pair (document feeding and discharging means) 7 introduction path (document guide) Reference numeral 7a Upper guide 7b Lower guide 8 Image reading position 9 Discharge path 10 Discharge / convey roller pair (document feeding and discharging means) 16 Photoconductor drum (image forming means) 21 Platen glass 22 Reading roller (document guiding means, rotating body) 26 Gap holding ring (document guiding means, gap holding member) 27 swing link 28 copier (image forming apparatus) 29 CPU 33 image reading unit (image reading means)

Claims (4)

[Claims] 1. A document feeding / discharging means for feeding the document to an image reading position for reading an image of the document and then discharging the document, and the image passing through a gap allowing passage of the document conveyed by the document feeding / discharging means. A document guiding device disposed opposite to the reading position, wherein the gap is set to about 0.1 mm to about 0.5 mm. 2. The image reading position is a surface of a platen glass through which the document passes by the document feed / discharge unit, and the document guide unit is rotatable to face the platen via the gap. A rotating body,
2. The document feeder according to claim 1, further comprising a gap holding member that holds the gap by contacting the platen glass. 3. 3. The document feeder according to claim 2, wherein the rotating body rotates at a peripheral speed substantially equal to a conveying speed of the document conveyed by the document feed / discharge unit. 4. The document feeder according to claim 1, wherein the document is read by an image reading unit that reads an image of a document sent by the document feeder. An image forming apparatus comprising: an image forming unit that forms an image on a sheet based on image information of a document.