JPH11334930A - Sheet material feeder and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet material feeder which certainly transfers a transfer paper to a nip part of a pair of register rollers and stably transfers it with no increase in load torque during register roller feeding, and to provide an image forming device with this sheet material feeder. SOLUTION: Positions of pre-register upper/lower guides (guide means) 4, 5 can be switched between a first position to guide a transfer paper (a sheet material) S to a nip part between a pair of register rollers (sheet material feeding means) 1 and a second position apart from the sheet material feeding path. When the transfer paper S is nipped between the pair of register rollers 1 so that guidance of the transfer paper S gets unnecessary, the positions of the pre register upper/lower guides 4, 5 are switched from the first position to the second position by solenoids 8, 9 (position changing means).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device in an image forming apparatus such as a copying machine.

[0002]

2. Description of the Related Art A schematic configuration of a conventional image forming apparatus is shown in FIG.
This will be described with reference to FIG. 3, reference numeral 101 denotes an image forming apparatus main body, 102 denotes a transfer paper S storage device, 103 denotes a paper feeding unit, 104 denotes a registration roller, 105 denotes an image forming unit, 106 denotes a conveying unit, 107 denotes a fixing device, and 108 denotes a discharging unit. A paper roller 109 is a loading tray.

The transfer paper S stored in the storage device 102
Is fed by the feeding means 103, and the registration roller pair 1
The sheet is conveyed so as to match the leading end of the image formed on the image forming unit 105 by the step S04.

Next, the formed image is transferred to a transfer sheet S, and guided to a fixing device 107 by a transport unit 106.

Further, the image on the transfer paper S is fixed by the fixing device 107, and is stacked on the stack tray 109 by the discharge roller 108.

FIG. 4 shows details of the configuration near the registration roller pair 104. In FIG. 4, reference numeral 111 denotes an upper guide before registration, 112 denotes a lower guide before registration, 113 denotes a guide before registration, and 114 and 115 denotes a pair of conveying rollers for conveying the transfer sheet S conveyed from the paper feeding unit to the pair of registration rollers 104. , 116 is an upper transfer guide, 117 is a lower transfer guide, 1
Reference numeral 18 denotes a photosensitive drum, 119 denotes a transfer charger, and 120 denotes a separation charger.

As shown in FIG. 4, the transfer paper S transported by the transport roller 115 is transferred to a pair of registration rollers 10.
In order to surely guide the nip of the registration roller pair 104 to the nip of No. 4, the nip is guided by the upper / lower / middle guides 111, 112, 113 before the registration extending to the vicinity of the nip.

Next, rotation starts in accordance with the registration roller pair 104 and the front end of the image formed on the photosensitive drum 118, and the transfer paper S is transported. Registration roller pair 10
The transfer paper S sent to the transfer paper 4
7 to the photosensitive drum 118, and the transfer charger 119
As a result, the image on the photosensitive drum 118 is transferred, and then the transfer paper S is separated from the photosensitive drum 118 by the separation charger 120 and conveyed to the transport unit 106.

[0009]

However, in recent years,
Due to diversification of user preferences, it has become necessary to transport thicker transfer paper (for example, paper (sheet material) of 120 to 250 g / m ² ) than the conventional transfer paper S.

On the other hand, as an apparatus configuration of the image forming apparatus main body 101, front-loading type copying machines capable of performing all operations such as jam processing from the front are increasing in order to improve usability. As a result, the paper path to the registration roller pair 104 must be bent.

In the background described above, in the conventional example, as shown in FIG. 5, the transfer paper S bent and conveyed and the upper / lower / middle guides 111,
112, 113 (in FIG. 5, the guide 11
3 is not shown), and when the transfer paper S is transported by the pair of registration rollers 104, the load (rotation torque) of the pair of registration rollers 104 is increased, and the transportability is stable. There was not. In particular, when the transfer path of the thick transfer paper is greatly bent as described above, it is remarkable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It is an object of the present invention to surely guide a transfer sheet to a nip portion of a pair of registration rollers and to reduce a load torque during conveyance of the registration rollers. It is an object of the present invention to provide a sheet material transporting device that realizes stable transportability without increasing image quality, and an image forming apparatus including the sheet material transporting device.

[0013]

In order to achieve the above object, according to the present invention, there is provided a sheet conveying means for pinching and conveying a sheet, and a guide for guiding the sheet conveyed toward the sheet conveying means. And a guide unit that guides a sheet material to a nip portion of the sheet material transport unit, and a guide unit that guides the sheet material to a nip portion of the sheet material transport unit. The guide member can be changed from the first position when the sheet member is sandwiched by the sheet member conveying means and the guide of the sheet member by the guide member becomes unnecessary. It is characterized by comprising a position change control means for changing to the second position.

The sheet material conveying means is a registration roller, and the position change control means positions the guide means at the first position while the registration roller is stopped, and the guide means during driving of the registration roller. It is also preferred that the means is located in the second position.

Preferably, the position change control means changes the guide means from a first position to a second position in synchronization with the driving of the registration roller.

The guide means is rotated by a rotation shaft to change between the first position and the second position, and the position change control means urges the guide means to the first position. It is also preferable to provide an urging means for driving the guide means and a driving means for rotating the guide means to the second position.

The image forming apparatus includes the above-described sheet material conveying device, and image forming means for forming an image on the sheet material conveyed by the sheet material conveying device.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described with reference to FIG. The image forming apparatus to which the present invention is applied has the same configuration as that of the electrophotographic image forming section described with reference to FIG. 3 with respect to the image forming section. The description here is omitted mutatis mutandis.

In FIG. 1, reference numeral 1 denotes a pair of registration rollers as sheet material transport means for transporting a transfer sheet S as a sheet material to an image forming unit. Is used to correct the posture and position in the middle of conveyance and to convey the transfer paper S in synchronization with the image forming unit. The transfer paper S is nipped and conveyed by two opposing pressure-contact rollers.

Reference numeral 2 denotes a transfer sheet S conveyed along a sheet material conveyance path (a path in which the transfer sheet S is conveyed in FIG. 1) by an upstream conveyance roller (not shown) to a nip portion of the registration roller pair 1. An upper guide before registration as guide means extending to the vicinity of the nip portion to reliably guide, a lower guide before registration as guide means similar to the upper guide 2 before registration,
Reference numerals 4 and 5 denote rotation axes of the upper / lower guides 2 and 3 in front of the cash register.

Reference numerals 6 and 7 denote upper / lower guides 2 and 3 as urging means for urging the transfer paper S to a first position (dotted line in the drawing) for guiding the transfer paper S to the nip portion of the registration roller pair 1. Springs 8 and 9 are solenoids which are drive means for rotating the upper / lower guides 2 and 3 in front of the register to a second position (solid line in the drawing) away from the sheet material conveyance path, and 10 and 11 are resists. An upper transfer guide and a lower transfer guide for guiding the transfer paper S conveyed by the pair of rollers to the photosensitive drum 12 on which an image is formed.

Therefore, the springs 8, 9 and the solenoids, 1
Reference numerals 0 and 11 function as position change control means for the upper / lower guides 2 and 3 before the cash register. The solenoids 10 and 11 are turned on / off.
The off control can be performed by adding a control function to a control unit provided in the image forming apparatus main body.

Next, in the above configuration, when the registration roller pair 1 is stopped, the upper guide 2 before registration and the lower guide 3 before registration are moved to positions indicated by dotted lines in FIG.
Position). Then, the transfer paper S transported by the transport rollers (not shown) is transferred to the upper guide 2 before the registration.
And the lower guide 3 before the registration ensures that the registration roller pair 1 is guided to the nip portion.

Next, when the registration roller pair 1 starts rotating in accordance with the leading end of the image formed on the photosensitive drum 12, the solenoids 8 and 9 are also turned on in synchronization with the signal, and the upper guide 2 before registration and The lower guide 3 before the cash register is rotated about the rotation centers 4 and 5 to the position shown by the solid line in the figure.

In this state, the transfer sheet S is transported by the registration roller pair 1. At this time, the sliding resistance of the upper guide 2 before registration and the lower guide 3 before registration of the transfer paper S is reduced. Particularly strong and thick transfer paper (120-250
g / m ² ), the sheet is conveyed while the sliding resistance is greatly reduced.

When the rotation of the pair of registration rollers 1 stops, the solenoids 8 and 9 are turned off, and the upper guide 2 before registration and the lower guide 3 before registration are positioned as indicated by dotted lines in FIG. Then, the operation is returned by the urging of the springs 6 and 7.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG.

In FIG. 1, reference numeral 1 denotes a pair of registration rollers for transporting the transfer paper S to the image forming unit, and reference numeral 2 denotes a pair for reliably guiding the transfer paper S transported by a transport roller (not shown) to the nip portion of the pair of registration rollers 1. The upper guide before the cash register extended to the vicinity of the nip portion, the lower guide 3 before the cash register similar to the upper guide 2 before the cash register,
Reference numerals 4 and 5 denote rotation axes of the respective guide plates, reference numerals 6 and 7 denote springs for urging the respective guide plates to a first position (dotted line in the drawing), and reference numeral 13 denotes a respective second position of the guide plates. (Solid line in the drawing), a cam M for rotating the motor, a motor 10 serving as a rotary driving means thereof, and a registration roller pair 10 for guiding the transfer paper S conveyed to the photosensitive drum 12 on which an image is formed. , A transfer upper guide and a transfer lower guide.

Next, in the above configuration, when the registration roller pair 1 is stopped, the upper guide 2 before registration and the lower guide 3 before registration are moved to the positions indicated by dotted lines in FIG.
Position). Then, the transfer paper S transported by the transport rollers (not shown) is transferred to the upper guide 2 before the registration.
And the upper guide 3 before the registration ensures that the registration roller pair 1 is guided to the nip portion.

Next, when the registration roller pair 1 starts rotating in accordance with the leading end of the image formed on the photosensitive drum, the motor M rotates in synchronization with the signal, and the cam 13 rotates to the position indicated by the solid line in the figure. The pre-registration upper guide 2 and the pre-registration lower guide 3 are rotated about the rotation centers 4 and 5 to the positions indicated by the solid lines in the drawing. In this state, the transfer sheet S is transported by the registration roller pair 1. At this time, the transfer paper S
The sliding resistance of the upper guide 2 before registration and the lower guide 3 before registration is reduced. Particularly strong thick paper (120-25
0 g / m ³ ) is conveyed in a greatly reduced state.

When the registration roller pair 1 stops rotating, the motor M rotates again, and the cam 13 rotates to the position indicated by the dotted line in the figure. It returns to the position shown by the dotted line by the bias of the springs 6 and 7.

[0032]

According to the present invention, the sliding resistance of the sheet material with the guide means when the sheet material is conveyed by the sheet material conveying means can be reduced, and the load on the sheet material conveying means can be suppressed to reduce the load on the sheet material conveying means. Can be stably conveyed.

[0033] By performing stable conveyance of the sheet material, the image forming quality in the image forming section can be maintained.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration near a pair of registration rollers according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration near a registration roller pair according to a second embodiment of the present invention;

FIG. 3 is a diagram illustrating a cross-sectional configuration of the image forming apparatus.

FIG. 4 is a diagram illustrating a configuration near a registration roller of the conventional image forming apparatus.

FIG. 5 is a diagram illustrating a configuration near a registration roller of the conventional image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Registration roller pair 2 Upper guide before registration 3 Lower guide before registration 4, 5 Rotating shaft 6, 7 Spring (biasing means) 8, 9 Solenoid 10 Transfer upper guide 11 Transfer lower guide 12 Photosensitive drum

Claims (5)

[Claims] 1. A sheet material conveying apparatus in which a sheet material conveying means for pinching and conveying a sheet material and a guide means for guiding a sheet material conveyed toward the sheet material conveying means are arranged in a sheet material conveying path. The guide means can be changed to a first position for guiding the sheet material to a nip portion of the sheet material transport means, and a second position separated from the sheet material transport path; When the sheet material is nipped by the means and the guide of the sheet material by the guide means becomes unnecessary, the apparatus further comprises position change control means for changing the guide means from the first position to the second position. Sheet conveying device. 2. The method according to claim 1, wherein the sheet material conveying unit is a registration roller, and the position change control unit is configured to position the guide unit at a first position while the registration roller is stopped. The sheet conveying apparatus according to claim 1, wherein the guide unit is located at a second position. 3. The apparatus according to claim 2, wherein the position change control means changes the guide means from a first position to a second position in synchronization with the driving of the registration roller.
The sheet material conveying device according to item 1. 4. The guide means is rotated by a rotation shaft to change between the first position and the second position, and the position change control means shifts the guide means to a first position. 4. The sheet conveying apparatus according to claim 1, further comprising: a biasing unit that biases and a driving unit that rotates the guide unit to a second position. 5. 5. A sheet conveying apparatus according to claim 1, further comprising: an image forming unit configured to form an image on the sheet conveyed by the sheet conveying apparatus. Image forming apparatus.