JPH11305495A - Automatic document feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a black stripe from appearing on a read image by preventing a foreign matter such as roller powder, dust or dirt from being retained at an image reading position. SOLUTION: Relating to this automatic document feeder equipped with a paper supply tray 5 on which a document is placed, a paper supply roller 30 feeding out the document on the tray 5, a feeding roller 22 guiding the fed-out document to an image reading part 24 along a paper supply path 23, and a paper ejection means guiding the read document to a paper ejection tray 6 along a paper ejection path 25, a guide plate 14 consisting of a dielectric is provided on the path 23 so that a document surface is brought into slidable contact with the projecting curved surface 40 of the guide plate 14 in the case of guiding the document to the reading part 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder used for an image reading apparatus such as a copying machine or a facsimile.

[0002]

2. Description of the Related Art Conventionally, an automatic document feeder installed on a copying machine main body generally automatically sends out originals stacked on a paper feed tray one by one, conveys them to an image reading position, and performs copying. The document is discharged onto an output tray after being read by an optical system in the main body of the apparatus.

In these automatic document feeders, a paper feed roller or a transport roller is used as a means for transporting a document on a paper feed tray to an image reading position. Is being transported. However, since the above-described paper feed roller and transport roller are generally made of a soft rubber material to secure a transport force, roller powder is generated due to friction when the document is transported, and the image is left attached to the document surface. There was a risk of being transported to the reading position. Then, the dust that has intruded into the conveyance path from the supply port of the roller powder or the document attached to the document surface,
Foreign matter G such as dust drops at the image reading position and stagnates on the platen of the copying machine main body, causing black streaks or so-called black streaks to appear on the image reading surface. Conventionally, as a measure against the black streak, a brush is arranged in front of the document reading position, and the brush is slid on the document surface to remove foreign matter G attached to the document surface (
).

[0004]

However, in the case where the brush is used as described above, the foreign matter G attached to the original surface can be removed at first. There is a problem that the foreign matter G removed from the sheet accumulates on the brush, and the accumulated foreign matter G adheres to the original surface. Further, with this brush, the foreign matter G that has fallen on the platen at the image reading position cannot be removed, so that the black streak of the original image due to the foreign matter G cannot be eliminated.

Accordingly, the present invention prevents foreign matter G such as roller powder, dust, and dust from staying at the image reading position,
An object of the present invention is to provide an automatic document feeder that prevents black streaks from appearing in a read image.

[0006]

In order to solve the above-mentioned problems, a paper feed tray on which a document is placed, paper feed means for feeding out the document on the paper feed tray, and a feed path for feeding the fed document are provided. An automatic document feeder having a transport means for guiding the read document along the paper path to the document reading section and a paper discharge means for guiding the read document along the paper discharge path to the paper discharge tray. A document is slid in contact with the guide section, and the surface of the document is charged, and then passed through the document reading section.

According to a second aspect of the present invention, there is provided an automatic document feeder, comprising: a first paper feed roller disposed upstream of the paper feed path; and a second paper feed roller disposed downstream thereof. Rollers, and the guide portion is provided between the first and second paper feed rollers, and the guide portion is located on a straight line connecting the respective document nip points of the first and second paper feed rollers. It is characterized by projecting toward the paper feed path.

The automatic document feeder according to a third aspect of the present invention is characterized in that the guide has a gentle projecting curved surface.

In the automatic document feeder according to a fourth aspect of the present invention, when the document is fed while being nipped by the first and second paper feed rollers, The document feed speed of the first and second paper feed rollers is controlled so that slippage occurs between the first paper feed roller and the document.

The automatic document feeder according to claim 5 of the present invention is characterized in that the guide portion is formed of resin.

According to a sixth aspect of the present invention, there is provided an automatic document feeder, comprising: a paper feed tray on which an original is placed; a paper feeding means for feeding out the original on the paper feed tray; In an automatic document feeder comprising a transport unit for guiding a document along a paper path to a document reading unit, and a paper discharge unit for guiding a read document to a paper discharge tray along a paper discharge path, the transport unit is made of a dielectric material. An elastic guide portion is disposed so as to be in contact therewith, and a document guided from the paper feed path is slid into contact with the elastic guide portion to charge the surface of the document and then pass through the document reading portion. I do.

In the automatic document feeder according to a seventh aspect of the present invention, the elastic guide portion is formed of a film member extending in the width direction of the document such that the elastic guide portion comes into contact with the conveying means in front of the document reading portion. It is characterized by the following.

In the automatic document feeder according to an eighth aspect of the present invention, a document fed while slidingly contacting the guide portion or the elastic guide portion does not contact a platen in the document reading portion. .

According to a ninth aspect of the present invention, there is provided an automatic document feeder, wherein a discharging member is provided at a downstream end of the paper discharge path to be in sliding contact with an image forming surface of the document.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an automatic document feeder according to the present invention will be described below in detail with reference to the accompanying drawings. In the automatic document feeder 1 shown in FIGS. 1 and 2, reference numeral 2 denotes a copying machine main body, reference numeral 3 denotes a platen provided on the copying machine main body 2, and reference numeral 4 denotes a document reading means arranged on the back side of the platen 3. In the automatic document feed, the position is fixed at the illustrated position.

The automatic document feeder 1 has a paper feed tray 5 on which a document is placed, a paper discharge tray 6 located above the paper feed tray 5, and an openable / closable cover which covers the entire transport section from above. It has a cover 8 and a number of ribs 9 protruding from the inner wall surface of the cover 8. A slide-type side guide member 10 for pressing both widths of the document is disposed on the paper feed tray 5, and a document width detection sensor (not shown) for detecting the width of the document based on the position of the side guide member 10. And a plurality of document length detection sensors (not shown) for detecting the length of the document placed on the paper feed tray 5 detect the size of the document. The original is placed on the paper feed tray 5 with the front side facing downward, and is sequentially sent out to the transport unit from the lowermost original.

The transport section includes a guide plate 14 formed by resin molding and a plurality of guide members 15, 16, and 17.
The guide plate 14 and the leading end of the discharge tray 6 form a paper feed port 19 facing the leading end of the document placed on the paper feed tray 5, and the guide member 17 and the discharge tray 6.
A first discharge port 20 is formed by the rear end, and a second discharge port 21 is formed by the guide member 17 and the rib 9.

A transport roller 22 is provided in the transport section at a position facing the document reading means 4.
The first sheet feed path 23 is formed between the sheet feeding roller 22 and the conveyance roller 22 via the guide plate 14. Also, the lip 9 inside the cover 8 and the transport roller 22, the guide members 16, 17, 1
5, a first paper discharge path 25 is formed, and a second paper discharge path 26 branched from the first paper discharge path 25 is formed by the rib 9 and the guide member 17. On the other hand, the guide member 1
The first paper discharge path 25 is conveyed by the conveying roller
The second paper feed path 27 branches from the middle of the path, and a re-sending path 28 is formed at a branch portion of the first paper discharge path 25, the second paper discharge path 26, and the second paper feed path 27.

The first paper feed path 23 communicates the paper feed port 19 with the original reading section 24, and the first paper discharge path 25 is connected to the original reading section 24.
The second paper discharge path 26 communicates with the middle part of the first paper discharge path 25 and the second paper discharge port 21, and the second paper supply path 27 communicates with the first paper discharge port 20. The middle part of the paper path 25 communicates with the first paper supply path 23, and the retransmission path 28 is connected to the second paper discharge path 26 and the first paper discharge path 2.
The second paper feed path 27 is communicated in five lines. Also, the second
The mylar 18 disposed at the branch position between the paper discharge path 26 and the re-sending path 28 is pushed down by the pressure when the document passes, and returns naturally as shown in FIG. When the document is retransmitted, the document is guided to the retransmission path 28 below the drawing.

On the other hand, the paper discharge tray 6 is formed above the paper supply port 19, receives originals discharged from the first and second paper discharge ports 20 and 21, and has a paper discharge rear end. Is supported to separate the original on the paper feed side from the original on the paper discharge side, so that the discharged original is not unexpectedly fed from the paper feed port 19. Further, a vertical wall portion 31 erected upward is integrally formed at the discharge side end of the discharge tray 6. The vertical wall portion 31 feeds the original discharged from the first and second discharge ports 20 and 21 such that the leading end of the discharged paper is higher than the trailing end of the discharged paper on the discharge tray 6. By inclining the tray 5, the original discharged from the first and second discharge outlets 20 and 21 is kept in alignment by contacting the trailing edge of the discharged original slipped by its own weight. .

In the first paper feed path 23, a paper feed port 19 is provided.
Rotating weight piece 2 that makes elastic contact with the top surface of the document near
9 and a substantially half-moon-shaped feed roller 30 located immediately below the feed roller 9
A separation roller 32 and a separation pad 33 for separating and feeding out the lowermost document are provided in the vicinity of the downstream of the paper feed roller 30. Further, near the downstream side of the separation roller 32, registration rollers 34 and 35 for abutting the leading end of the fed-out original to perform alignment are provided. First paper feed path 23
And at the position where the second sheet feed path 27 intersects, the sheet is brought into contact with the peripheral surface of the conveying roller 22 to be guided to the document reading section 24, and
A pinch roller 38 for registering a document fed from the paper feed path 27 is provided. The registration rollers 34,
Guide plate 14 from 35 toward pinch roller 38
1 to 3, the downstream side of the registration rollers 34 and 35 is slightly inclined upward as shown in FIG. 1 to FIG.
0 is formed. The projecting curved surface 40 projects above a straight line 41 connecting the original nip points of the registration rollers 34 and 35 and the pinch roller 38.

As shown in FIG. 3, a band-shaped mylar 42 is disposed near the document reading section 24 so as to be in contact with the transport roller 22. This Myra 42
It extends in a belt shape in a direction orthogonal to the document transport direction, and is supported by a support member 43 disposed below the guide plate 14.

In the course of the first paper discharge path 25, the outer peripheral surfaces of the guide belt 44 and the transport roller 22 which promote bending of the paper discharge front end and reduce the impact of the paper feed front end are provided. A contacting guide roller 47 is provided.
Forward and reverse rotation rollers 48 are provided at the exit ends of the paper discharge ports 20 and 21 for discharging the document or temporarily sending the document in the discharge direction, and then re-transmitting the document. The rollers 52 and 53 are in pressure contact. Further, intermediate drive rollers 49 and 50 for document conveyance are disposed at a branch portion between the first paper discharge path 25 and the second paper supply path 27, and a flapper 51 for switching document conveyance is disposed near the rollers. ing.

Next, a description will be given of the document conveying means of the automatic document feeder having the above-described configuration. The document placed on the paper feed tray 5 is fed out to the first paper feed path 23 by the paper feed roller 30, and only one sheet is separated by the separation roller 32 and the separation pad 33. Registration roller 34,
The leading edge of the document abuts on the document 35 and is aligned, and is guided to the rear end of the first sheet feeding path 23 by the registration rollers 34 and 35 rotating again. As shown in FIG. 4, the leading end of the document is guided to the pinch roller 38 while wrapping around the projecting curved surface 40 formed on the guide plate 14. At this time, the original is nipped at the leading end by the transport roller 22 and the pinch roller 38 and nipped at the rear by the registration rollers 34 and 35. Therefore, the rotation speed of the registration rollers 34 and 35 is reduced or stopped. Then, the document is sent to the document reading unit 24 in a state where the document is pulled by the conveyance force of the conveyance roller 22.
Since the original surface is rubbed and rubbed by the protruding curved surface 40, static electricity is easily charged on the original surface.

Further, the original is rubbed by the mylar 42 even immediately before the original reading section 24, so that the static electricity is further easily charged, and the roller which stays near the original conveying path and the original reading section 24 by the action of the static electricity. Foreign matter G such as powder, paper powder, dust, and dust is electrostatically attracted to the document surface. The read document is guided to the second paper discharge path 26 by the guide belt 44 and the transport roller 22 with the roller powder and dust adhered thereto.
It is discharged while being guided by the ribs 9 provided on the inner side surface of the sheet. When exposing the leading end side of the document from the second paper exit 21, the static electricity charged on the surface of the document was removed by the neutralization brush 54 provided near the forward / reverse rotation roller 48, and at the same time, adhered to the surface. Roller dust, paper dust, dust, dust, etc. fall from the document surface. In the case of single-sided reading of an original, the original is re-transmitted by rotating the forward / reverse rotation roller 48 in the reverse direction to reversely feed the second discharge path 26 and simultaneously switching the flapper 51 to shut off the second paper supply path 27. The paper is guided to the first paper discharge path 25 via the path 28, and is discharged from the first paper discharge port 20 onto the paper discharge tray 6. At this time, the surface of the document is discharged again by the discharging brush 55 provided at the exit end of the first paper discharge port 20 so that the documents are not brought close to each other on the paper discharge tray 6.

On the other hand, when reading both sides of the original, the original which has been read from the front side of the original and once discharged to the second paper output path 26 is re-rotated by the forward / reverse rotation roller 48 in the re-feed path 28.
And the flapper 51 is switched to shut off the first paper discharge path 25 side. Then, the document is guided from the re-feeding path 28 to the second sheet feeding path 27, and the back side of the document is read again by the document reading unit 4. At this time, static electricity is charged on the back side of the document mainly by the mylar 42 arranged below the transport roller 22, and thereby foreign matters G such as roller powder and dust staying in the document reading unit 24 are printed on the paper surface as described above. Attach. The document whose back side has been read is guided to the second paper discharge path 26, and is discharged onto the paper discharge tray 6 from the second paper discharge port 21 by the forward / reverse rotation roller 48. At this time, the back side of the document is neutralized by the neutralization brush 54 provided near the forward / reverse rotation roller 48.

The charging operation will be described in more detail. When the guide plate 14 is formed of polystyrene resin, the original surface is positively charged because the original is made of cellulose (FIG. 5, (A)). The original conveyed to the original reading unit 24 has a positively charged original surface, so that the neutralized roller powder, paper powder, dust, dust, and other foreign substances G staying in the original reading unit 24 are removed. Attracts negative charges. As a result, the foreign matter G is attracted to the original surface (FIG. 5,
(B)).

When the original reading section 24 is made of platen glass, the platen glass and the foreign matter G are negatively charged by passing the positively charged original surface over the platen glass, and the foreign matter G is attracted. Although the effect is also reduced, the negative charge spontaneously discharges and returns to the neutralized state after a predetermined time has elapsed after the document is conveyed. That is, since the next document is placed in the neutralization state before being placed on the paper feed tray 5 and conveyed to the reading unit, when the first document is conveyed to the document reading unit 24, The effect of adsorbing the foreign matter G is reliably performed. Of course, the document reading unit 24
If you want to make all of the documents conveyed to
What is necessary is just to apply a conductive coating agent to the surface of the platen glass and ground it, and keep the platen glass and the foreign matter G in a neutralized state.

Next, regarding the charging of the original surface by the Mylar 42, for example, when the Mylar 42 is formed of polyethylene resin, the original surface is positively charged because the original is cellulose. The original conveyed to the original reading unit 24 attracts the negative charge of the neutralized foreign matter G staying in the original reading unit 24 because the original surface is positively charged. G is adsorbed.

As described above, in the automatic document feeder of the present invention, the roller powder, paper powder, dust, dust, etc. remaining in the paper feed path during the document transport are positively adhered to the document transport surface. Since the foreign matter G is removed from the sheet feeding path, the foreign matter G does not stay in the image reading unit, and the printing surface is not stained with black stripes.

Further, since the adhesion of the foreign matter G due to static electricity can be achieved only by transporting the document while rubbing the original on the projecting curved surface provided in the paper feed path, roller dust and dust can be removed from the paper feed path without providing any special removing means. Foreign matter G such as can be removed.

[0032]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the entire configuration of an automatic document feeder according to the present invention.

[0033]

FIG. 2 is an enlarged sectional view of a main part of the automatic document feeder.

FIG. 3 is a perspective view illustrating a structure near a first sheet feeding unit and a conveyance roller.

[0034]

FIG. 4 is an explanatory view showing a document feeding state in the automatic document feeder.

[0035]

FIG. 5 is an explanatory view showing a state in which a sheet charged with static electricity adsorbs foreign matter.

[0036]

[Explanation of symbols]

 Reference Signs List 1 automatic document feeder 5 paper feed tray 14 guide plate 22 transport roller 23 first paper feed path 24 document reading unit 25 first paper discharge path 26 second paper discharge path 27 second paper feed path 34, 35 1 sheet feeding roller) 38 pinch roller (second sheet feeding roller) 40 projecting curved surface (guide section) 41 straight line 42 mylar (elastic guide section) -4-

Claims (9)

[Claims] A sheet feeding tray on which a document is placed; sheet feeding means for feeding the document on the sheet feeding tray; conveying means for guiding the fed document along a sheet feeding path to a document reading unit; An automatic document feeder having a paper discharge means for guiding a read document along a paper discharge path to a paper discharge tray, wherein a guide portion made of a dielectric material is provided in the paper feed path, and the document slides on the guide portion. An automatic document feeder, wherein the document is passed through the document reading section after the surface of the document is charged. 2. A sheet feeding apparatus comprising: a first sheet feeding roller disposed upstream of the sheet feeding path; and a second sheet feeding roller disposed downstream of the first sheet feeding roller. The guide portion is provided between rollers, and the guide portion protrudes toward a paper feed path from a straight line connecting the respective document nip points of the first and second paper feed rollers. 1. The automatic document feeder according to 1. 3. The automatic document feeder according to claim 2, wherein said guide portion has a gentle projecting curved surface. 4. When a document is fed in a state where the document is nipped by each of the first paper feed roller and the second paper feed roller, slippage occurs between the first paper feed roller and the document. 3. The automatic document feeder according to claim 2, wherein the document feed speeds of said first and second paper feed rollers are controlled so as to generate the document. 5. The automatic document feeder according to claim 1, wherein said guide portion is formed of resin. 6. A paper feed tray on which a document is placed, paper feed means for feeding out the document on the paper feed tray, transport means for guiding the fed document along a paper feed path to a document reading unit, An automatic document feeder having a paper discharge means for guiding the read document along a paper discharge path to a paper discharge tray, wherein an elastic guide portion made of a dielectric material is disposed in contact with the transport means, An automatic document feeder, wherein a document guided from the document is slid in contact with the elastic guide portion to charge the surface of the document, and then passes through the document reading portion. 7. The automatic document feeder according to claim 6, wherein the elastic guide portion is formed of a film member extending in a document width direction so as to be in contact with a conveying unit before the document reading portion. apparatus. 8. The automatic document feeder according to claim 1, wherein the document fed while slidingly contacting the guide section or the elastic guide section does not contact the platen in the document reading section. 9. The image forming apparatus according to claim 1, further comprising: a discharging member provided at a downstream end of the paper discharge path to be in sliding contact with an image forming surface of the document.
Or the automatic document feeder according to 6.