JPH10212048A - Paper conveyance guide mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide paper conveyance guide mechanism that can dissolve the generation of noise caused by rubbing between paper and a guide sheet, which is a defect liable to generate in case of heightening conveying capability by extending a flexible thin guide sheet close to a nip part at the time of leading the paper to the nip part of a carrier roller pair. SOLUTION: Paper conveyance guide mechanism is provided with upper and lower rigid guide plates 3, 5 positioned on the front side of a pair of carrier rollers 1, 2 so as to guide paper P to a pair of carrier rollers 1, 2 for conveying the paper P by holding the paper P between nip parts, a guide sheet 6 protruded toward the carrier roller pair from the tip part of one guide plate out of the upper and lower guide plates 3, 5, another guide sheet 20 placed in a position of guiding entry of the paper P at the time of the paper entering the nip part of a pair of carrier rollers 1, 2 and retreated into a position of not coming in contact with the paper in conveyance when conveyance of paper held between a pair of carrier rollers 1, 2 is started, and a guide bracket 12 for supporting the guide sheet 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer,
The present invention relates to a paper transport mechanism used in an image forming apparatus such as a facsimile apparatus and a printing apparatus, and more particularly to a paper transport guide mechanism having improved transportability in a paper transport mechanism including a pair of transport rollers.

[0002]

2. Description of the Related Art As an apparatus provided with a paper transport mechanism, an image forming apparatus such as a copying machine, a printer, a facsimile apparatus, and a printing apparatus is representative. The current mainstream of the paper transport mechanism is the transport. This is a transport mechanism using a roller pair. This transport system has the advantage that the configuration is simple and that the paper is fed to the nip portion between the two rollers so that it can be transported reliably. However, in a transport mechanism using a pair of transport rollers, when a guide plate arranged to guide the paper to the nip portion of the two rollers guides the paper, the leading edge of the paper is moved with respect to the nip portion of the transport roller pair. If not guided correctly, the leading edge of the paper may be broken by hitting the roller surface shifted from the nip, and in the worst case, jamming may occur. In order to ensure that the leading edge of the paper is directed toward the nip portion, it is necessary to ensure the positioning accuracy of the guide plate and the rollers, and an adjustment work is required. However, even if the precision adjustment is surely performed, if the front end of the paper has a curl, the paper is likely to be broken, which causes a jam. As a method for solving such a problem, while a driving roller of the transport roller pair is a rubber roller,
The driven roller is a metal or plastic roller whose surface slides easily so that the leading end of the paper is not easily caught, and the guide plate is oriented so that the leading end of the paper faces the slippery surface of the driven roller. Thereby, even if the leading edge of the paper is guided to the driven roller side from the nip portion, troubles such as breakage of the leading edge of the paper do not occur.
In many cases, the guide member near the transport roller pair is formed of a thin plate material such as mylar or a thin metal plate, and the tip of the guide member extends to near the nip portion of the transport roller pair.

FIGS. 4 (a) and 4 (b) are views for further detailing the above-mentioned conventional example and its disadvantages. A paper is provided downstream of a pair of conveying rollers (a driven roller 1 and a driving roller 2). An upper guide plate 5 for guiding P, an upper guide sheet 6 provided at a tip end thereof, a lower guide plate 3, and a lower guide sheet 4 provided at a tip end thereof are arranged. Lower guide sheet 4
Is directed to the surface of the driven-side roller 1 (made of metal or plastic and easily slipped) so that the leading end of the paper P does not face the surface of the drive-side roller 2 (made of rubber). As a result, even if the position of the lower guide sheet 4 varies slightly, and even if there is a curl at the leading end of the paper P, the leading end of the paper does not break, but as shown in FIG. One, two
When the paper P is conveyed, the lower guide sheet 4 and the paper P are rubbed, so that an abnormal noise is generated. As described above, in the above-described conventional paper transport mechanism, the guideability of the paper to the nip portion of the transport roller pair is improved, but abnormal noise is generated because the paper rubs on the guide sheet during the transport of the paper. In recent years, since noise reduction of image forming apparatuses such as copying machines has become important, the problem of abnormal noise has become a very important problem to be solved. The present invention has been made in view of the above, and when guiding paper to a nip portion of a transport roller pair, a flexible thin sheet guide sheet is extended to the vicinity of the nip portion to enhance transportability. An object of the present invention is to provide a paper transport guide mechanism that can eliminate the generation of abnormal noise due to the rubbing between paper and a guide sheet, which is a drawback that is likely to occur in the case where the paper transport guide mechanism is used.
That is, the invention of claim 1 aims at improving the quietness, the invention of claim 2 aims at further improving the reliability, and the invention of claim 3 aims at further improving the reliability.

[0004]

In order to achieve the above object,
The invention according to claim 1 is an upper and lower guide plate having rigidity for guiding the paper to the pair of transport rollers that is located in front of the pair of transport rollers that transports the paper by sandwiching the paper in the nip portion,
A guide sheet protruding from the tip end of one of the upper and lower guide plates toward the pair of transport rollers, and guiding the paper when entering the nip portion of the pair of transport rollers. And the other guide sheet retracts to a position where it does not come into contact with the paper being conveyed when the paper is held by the conveying roller pair and is conveyed, and a guide bracket for supporting the guide sheet. It is characterized by the following. The invention according to claim 2 is such that when the other guide sheet is at a position for guiding the paper entering the nip portion of the transport roller pair, the guide bracket is not moved by the pressing force from the entered paper. The guide bracket is configured to be pressed against the stopper portion by a component force of the pressing force. According to a third aspect of the present invention, the guide bracket is rotatably supported by an outer periphery of a bearing that supports a shaft of one of the transport rollers of the transport roller pair, and the other guide supported by the guide bracket. The stopper for supporting the guide bracket when the sheet is located at a position for guiding the paper entering the nip portion is a bearing of the other transport roller.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. 1A and 1B are front views showing the configuration and operation of a paper transport guide mechanism according to an embodiment of the present invention, and FIG. 2 is a right side view thereof. The transport roller pairs 1 and 2, the lower guide plate 3, the upper guide plate 5, and the upper guide sheet (one guide sheet) 6 shown in FIG. This paper transport guide mechanism is characterized in that it can be improved by adding components such as the lower guide bracket 12 and the solenoid 13 to the existing transport roller pairs 1 and 2. That is, the characteristic configuration of this paper transport guide mechanism is that the paper transport guide mechanism slides on the outer periphery of the bearing 10 (supported by the side plate 16) that supports the outer peripheral surfaces of the two rotating shafts 2 a of the driving roller 2, and turns. The lower guide bracket 12 is rotated by the driving force of the solenoid 13 and one end of the lower guide sheet 20 is fixed to an appropriate position of the lower guide bracket. That is, as shown in FIG. 2, the lower guide bracket 12 has a C-shaped engaging portion 12 a rotatably attached to the outer periphery of the drive-side bearing 10, and a solenoid connected via a link 14. Spring 15 when 13 is OFF
, So as to rotate in the counterclockwise direction (paper entry guide position). Further, positioning is performed by the engaging portion 12b of the lower guide bracket 12 abutting on the outer peripheral surface of the driven bearing 11 that supports the shaft 1a of the driven roller. That is, the state of (a) in which the engaging portion 12b is in contact with the driven-side bearing (stopper portion) 11 is when the paper enters, and the lower guide sheet (the other end) supported by the lower guide bracket 12 at this time. Guide sheet) 20 is paper P
Of the driven roller 1 is guided toward the outer peripheral surface (above the nip portion) of the driven roller 1 into the paper movement area. The lower guide member 3 and the upper guide member 5
Is made of a plate having a relatively high rigidity, and the upper and lower guide sheets 6 and 20 are made of a thin plate such as a mylar or a thin metal plate.

FIG. 1B shows a state in which the lower guide bracket 12 rotates clockwise (retreating direction) against the spring 15 when the solenoid 13 is turned on. In other words, when the paper is held at the nip portion of the pair of transport rollers 1 and 2 and the paper can be transported, FIG.
As shown in (b), when the pair of conveying rollers 1 and 2 starts to convey the paper, a control unit (CPU, ROM, RAM, etc.) (not shown) turns on the solenoid 13 and pulls the link 14 to lower the lower guide. Since the sheet 20 is retracted from the area where the paper P is present to eliminate the rubbing with the paper, no abnormal noise is generated. The detection of the transport start timing is performed by a paper detection sensor (not shown) disposed downstream of the transport roller pairs 1 and 2. Further, the movement of the lower guide bracket 12 is a rotational movement about the drive roller bearing 10 of the transport roller pair as a fulcrum,
By using the bearing 11 of the driven roller as a stopper when the lower guide bracket 12 is positioned to guide the paper inflow (the state shown in FIG. 1A), the pair of transport rollers 1 and 2 and the guide are used. Position accuracy with the lower guide bracket 12 (guide sheet 20) when the position is in a position where the paper is broken, a paper jam that occurs when the position accuracy of the two is poor, and a gap between the conveying roller pair and the guide bracket 12 are generated. The generation of abnormal noise due to a hit and the displacement of the lower guide sheet 20 can be prevented, and the reliability can be improved.

Next, FIG. 3 is a front view for explaining the configuration of another embodiment of the present invention, and the same parts as those in FIG. 1 are denoted by the same reference numerals, and duplicate description will be omitted. A characteristic configuration of this embodiment is that the leading end of the paper P, which is guided by the guide plates 3 and 5 toward the nip portion of the conveying roller pair 1 and 2, is located at the illustrated paper entry guide position. The component force Fa of the pressing force F generated at the time of contact with the seat 20 is at the point where the engaging portion 12b of the lower guide bracket 12 comes into contact with the outer peripheral surface of the driven bearing 11 (stopper). As a result, the lower guide bracket 12 can be securely pressed against the driven bearing 11, and the lower guide bracket 12 does not rattle when paper enters, thereby improving reliability. This embodiment is particularly effective when passing thick paper. That is, the force F received when the leading edge of the paper P that has entered the lower guide sheet 20 is applied is F
a (force acting in the direction of rotating the lower guide bracket 12 in the counterclockwise direction) and Fb (force acting on the rotation fulcrum of the lower guide bracket 12). Fa acts on the stopper side (in the direction of the driven-side bearing 11) at the time of paper entry, thereby preventing the lower guide bracket 12 from moving due to the force applied by the paper. In the above embodiment, the guide bracket is rotatably supported by the lower drive bearing while the upper transport roller is the driven roller, but this is merely an example, and the upper bracket may be reversed. That is, the guide bracket may be rotatably supported by the upper drive bearing while the lower transport roller is the driven roller.

[0008]

As described above, according to the first aspect of the present invention,
Since the lower guide sheet 20 moves to a position where the lower guide sheet 20 does not come into contact with the paper after the paper is nipped by the transport rollers 1 and 2, the noise of rubbing between the paper and the lower guide sheet is eliminated, and the quietness is improved. According to the second aspect of the invention, the pressing force generated when the entering paper comes into contact with the lower guide sheet is applied to the stopper at the position where the lower guide bracket is guided. The lower guide bracket does not rattle when the vehicle enters, and the reliability is improved. In particular, rattling can be effectively prevented when a thick paper having a strong waist is passed. According to the third aspect of the present invention, the movement of the lower guide bracket 12 is a rotational movement about the drive roller bearing 10 of the transport roller pair as a fulcrum, and the position at which the lower guide bracket 12 guides paper entry. By using the bearing portion 11 of the driven roller as a stopper when the lower side comes to the side, the accuracy of the position of the lower guide bracket 12 when it is in the position to guide the pair of conveying rollers 1 and 2 is improved, and the position of both the rollers is improved. It also prevents paper breakage and paper jams that occur when accuracy is poor, abnormal noise caused by contact between the pair of transport rollers and the lower guide bracket, and slippage of the lower guide sheet, thereby improving reliability. .

[Brief description of the drawings]

FIGS. 1A and 1B are front views showing the configuration and operation of a paper transport guide mechanism according to an embodiment of the present invention.

FIG. 2 is a right side view of FIG.

FIG. 3 is a configuration diagram of another embodiment of the present invention.

FIGS. 4A and 4B are explanatory diagrams of a configuration of a conventional example.

[Explanation of symbols]

1, 2 transport rollers, 3 lower guide plates, 4 lower guide sheets, 5 upper guide plates, 6 upper guide sheets,
10 bearings, 11 bearings, 12 lower guide brackets, 13 solenoids, 20 lower guide sheets.

Claims (3)

[Claims] An upper and lower guide plate having rigidity for guiding paper to a pair of transport rollers, which is located in front of a pair of transport rollers for transporting the paper by sandwiching the paper in a nip portion, and And a guide sheet protruding from the leading end of one of the guide plates toward the pair of transport rollers, wherein the guide sheet is located at a position for guiding the entry when paper enters the nip portion of the pair of transport rollers. When the paper is added to the transport roller pair and the paper is started to be transported, the other guide sheet is retracted to a position where the paper is not in contact with the paper being transported, and a guide bracket that supports the guide sheet and moves forward and backward is provided. Paper transport guide mechanism. 2. When the other guide sheet is at a position for guiding paper entering the nip portion of the transport roller pair, the guide bracket is not moved by a pressing force from the entered paper. 2. The paper transport guide mechanism according to claim 1, wherein said guide bracket is pressed against said stopper portion by a force component of pressure. 3. The guide bracket is rotatably supported by an outer periphery of a bearing that supports a shaft of one of the transport rollers of the transport roller pair, and the other guide sheet supported by the guide bracket is supported by the guide bracket. 3. The paper transport guide mechanism according to claim 1, wherein the stopper portion that supports the guide bracket when it is located at a position guiding the paper entering the nip portion is a bearing of the other transport roller.