JPH10198207A - Recording material carrying roller device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simple recording material carrying roller device which is reducible in size and capable of smoothly receiving and ejecting a fed recording material, without damaging it. SOLUTION: This device is provided with a driving roller 51 and a driven roller 52 which faces it and carries the fed recording material S, while holding it between the driving roller 51 and the driven roller 52. In such a case, the driven roller 52 is freely rotatably supported by a holding member 53 and this holding member 53 includes a guiding part 530 for leading the recording material S into the gap between the driving roller 51 and the driven roller 52. Then, the guiding part 530 includes a a curved surface 531a facing the driving roller 51 and having a small-diameter circular shape, when viewed from the side surface and a slope 531b extended to the upstream side in the carrying direction of the recording material, to be continuous to the curved surface 531a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material transport roller device for transporting a recording material such as paper in an image forming apparatus such as an electrophotographic copying machine or a printer.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic printer or copier, the surface of an electrostatic latent image carrier is usually charged by a charging device, and an image exposure corresponding to a document image is performed in the charged area. Is applied to form an electrostatic latent image. The latent image is developed by a developing device into a visible toner image, and the toner image is transferred to a recording material as it is or further transferred to an intermediate image carrier. Is fixed on the recording material in a fixing device. Thereafter, the recording material is discharged.

In such an image forming process,
Usually, the recording material is conveyed at a predetermined timing, and the toner image is transferred, fixed and discharged thereon as described above. During that time, the recording material may curl (warp or bend). As a result, the recording material may be clogged, or the leading end of the recording material may be bent or broken. Also, if the finally discharged recording material has a curl, the discharging of the recording material to the discharge tray itself may not be performed smoothly, or the consistency of the recording material on the discharge tray may be affected. I do.

[0004] Such curling is particularly likely to occur in a fixing device for fixing an unfixed toner image to a recording material. This is because a fixing device usually fixes an unfixed toner image on a recording material under heat and pressure by a fixing roller pair including a heating roller and a pressure roller. It's easy to do. If the recording material conveying roller device on the downstream side of the fixing roller is taken as an example, the recording material that has passed through the fixing roller pair is easily curled toward the heating roller, so that the conveying roller device fixes the roller nip portion. It is arranged so as to be shifted with respect to the recording material passing direction in the roller nip portion, and further, the roller or roller on the heating roller side of the conveying roller device is shifted downstream in the recording material conveying direction with respect to the other roller or roller. It is devised such as arranging.

[0005]

However, even with the above arrangement, when the recording material exiting the fixing roller pair enters the downstream conveying roller device due to the curl, the recording material in the conveying roller device may be disturbed due to the curl. When the recording material gets on one roller or the roller or collides with the supporting member of the roller or the roller, the leading edge of the recording material may be bent or broken. Particularly, today, in order to respond to the demand for downsizing of the image forming apparatus and the demand for reducing the heat capacity of the fixing roller for shortening the so-called warming-up time required for increasing the temperature from the start of energization to a predetermined fixing temperature, a heating roller and a heating roller are required. As the diameter of the pressure roller is reduced, the amount of curl of the recording material is further increased, and such inconvenience is likely to occur.

To solve such a problem, for example,
Japanese Utility Model Application Laid-Open No. 62-120755 and Japanese Utility Model Application Laid-Open No.
It is conceivable to employ a recording material guiding means taught by Japanese Patent Publication No. 72-72, but such a guiding means is provided between a fixing roller pair and a recording material conveying roller device on the downstream side of the fixing roller pair. In addition, it hinders downsizing and downsizing, and the provision of such a guide means increases costs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a simple and compact recording material transport roller device capable of smoothly receiving and discharging a recording material without being damaged.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention comprises a driving roller and a driven roller facing the driving roller, and feeds a recording material between the driving roller and the driven roller. A recording material conveying roller device for nipping and conveying, wherein the driven roller is rotatably supported by a holding member, and the holding member includes a guide portion for guiding the recording material between the driving roller and the driven roller. The guide portion includes a curved surface facing the drive roller and having an arc shape smaller in diameter than the driven roller in side view, and a slope extending continuously upstream from the curved surface in the recording material conveyance direction. And a recording material conveying roller device characterized by the following.

In the recording material conveying roller device according to the present invention, even if the leading end of the fed recording material is curled, the recording material is guided in the direction in which the curl is bent back by contacting the guide portion. By arranging and using it so as to be guided to the nip portion between the driving roller and the driven roller, it is possible to smoothly receive and discharge the sent recording material. Further, in the recording material conveying roller device according to the present invention, the guide portion is not provided separately, but utilizes a driven roller holding member,
Since it is provided there, the device can be simplified, miniaturized, and compact.

The holding member is not limited to this, but can be formed from a sheet metal in consideration of the fact that it is easy to manufacture inexpensively and compactly. In this case, the guide portion may be formed by an edge portion of the holding member facing the drive roller and subjected to bending drawing. Further, the holding member may use a main body formed of a sheet metal, and the guide portion may be formed separately from the main body with a synthetic resin or the like and mounted on the main body.

The driven roller may be brought into pressure contact with the drive roller by a spring. In this case, the driven roller is brought into pressure contact with a plate spring, and the plate spring is formed integrally with the holding member from the sheet metal. be able to. In any case, the recording material transport roller device according to the present invention can be adopted as a recording material transport roller device disposed downstream of the fixing roller pair in the fixing device in the recording material transport direction. Even the curled recording material that has come out of the pair can be smoothly received and discharged.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic cross-sectional view (a schematic cross-sectional view crossing a rotation center axis of a roller) of a fixing device in an electrophotographic image forming apparatus, more specifically, a fixing device including a recording material conveying roller device 5 according to the present invention. Yes, Figure 2
FIG. 3 is another schematic cross-sectional view of the fixing device (a schematic cross-sectional view along a rotation center axis of a roller).

The fixing device shown in FIGS. 1 and 2 includes a heating roller 1 and a pressure roller 2 opposed thereto. Further, the recording material transport roller device 5 is provided downstream of these rollers in the recording material transport direction α. FIG.
G1 and G2 are guide plates for guiding the recording material. As shown in detail in FIG. 2, the heating roller 1 is rotatably supported at both ends by bearings 31. The left and right bearings 31 are supported by the fixing device housing H.

A ring gear 14 is provided on the outer peripheral surface of one end (the right end in FIG. 1) of the heating roller 1, and the gear 14 is provided via a gear train GT1 (see FIG. 1). Can be driven by a motor M.
Are driven to rotate clockwise in FIG. Pressure roller 2
The shaft 21 provided at both ends thereof is rotatably supported by a support member 32, and is pressed toward the heating roller 1 by a spring 321 contacting the support member 32 from one direction. The pressure roller 2 rotates following the rotation of the heating roller 1 or following the movement of the recording material passed between the rollers.

The heating roller 1 has a core roller 10 (although the invention is not limited thereto, a hollow cylindrical aluminum alloy is used here), and an insulating layer 11 and a layered resistance are formed on the inner peripheral surface of the core roller 10. Heating element (hereinafter referred to as resistance heating layer)
12 are sequentially formed, and the release layer 1 is formed on the outer peripheral surface.
3 are formed. The insulating layer 11 is formed between the resistance heating layer 12 and the core roller 10 in order to maintain electrical insulation between them. In this example, the insulating layer 11 is made of a heat-resistant insulating resin polyimide.

The resistance heating layer 12 itself generates Joule heat by energization, and in this embodiment is made of barium titanate ceramic. When the recording material holding the unfixed toner image passes while being held between the heating roller 1 and the pressure roller 2 opposed thereto, the release layer 13 removes the heated toner image from the heating roller 1. It is formed so as to be easily peeled off, and in this example, is made of polytetrafluoroethylene.

The insulating layer 11, the resistance heating layer 12, and the release layer 13 rotate integrally with the core roller 10. Power receiving members 15 are attached to both ends of the heating roller 1 in the rotation center axis direction. Although not limited to this, it is fitted on the inner peripheral surface side of the core roller 10 here. Each power receiving member 15 is a cap-shaped member having a flat circular top surface 151 whose center line coincides with the rotation center axis of the roller 1 and is made of a conductive material, for example, brass or the like. Is connected and fixed to the resistance heating layer 12 by a conductive adhesive, and is electrically connected to the resistance heating layer 12. The power receiving member 15 rotates integrally with the heating roller 1.

A power supply member 16 made of a conductive material, for example, copper-based carbon or the like, is in surface contact with the flat top surface 151 of each power receiving member 15 from the outside in the rotation center axis direction of the heating roller 1. The power feeding member 16 on the left side in FIG.
The spring 161 fitted in the recess 411 partially protrudes from the hole 411 a provided on the roller 1 side and faces the power receiving member 15.
Contacts the power receiving member 15 under an appropriate pressure. The right power supply member 16 is also fitted into the recess 421 of the right holder 42, partially protrudes from the holder hole 421 a and faces the right power receiving member 15, and the spring 161 fitted in the recess 421.
Contacts the right power receiving member 15 under an appropriate pressure. The outer end of each spring 161 is supported by a terminal plate 33 screwed to the outer end of the holder. Thus, even if the power receiving member 15 rotates integrally with the heating roller 1, the electrical connection between the two can be maintained.

The holders 41 and 42 are screwed to the housing. Each power supply member 16 has a lead wire 162
Are electrically connected to the terminal plate 33 respectively.
On one terminal plate 33 (the one on the left side in FIG. 1), an electric wire 34 connected to the power source 8 (see FIG. 5) is connected to a crimp terminal 34.
1 and the other terminal plate 33 (the one on the right side in FIG. 1) has a solid state relay S
An electric wire 34 connected to the other end of the power supply 8 via the SR (see FIG. 5) is connected by a crimp terminal 341.

FIG. 5 shows a schematic diagram of a circuit for energizing the resistance heating layer 12, together with a control section for controlling the energization. In addition,
In FIG. 5, the power receiving member 15 and the power supply member 16 are not shown. Electric power can be supplied to the resistance heating layer 12 from the power supply 8 by closing the relay SSR. A control unit CTR including a central processing unit (CPU) for controlling the operation of the entire fixing device is connected to the relay SSR.
The relay SSR is opened and closed by the control unit CTR. The control unit CTR is based on the temperature of the heating roller 1 detected by a thermistor TH (not shown in FIG. 1) which is a temperature detecting element abutting on the outer peripheral surface of the release layer 13 of the heating roller 1. Open and close the relay SSR. That is, based on the temperature of the heating roller 1 detected by the thermistor TH, the control unit CTR controls the energization of the resistance heating layer 12 and controls the heating roller 1 to a predetermined temperature.

In addition to the thermistor TH for controlling the temperature of the heating roller 1, a temperature detecting element for preventing abnormal heating of the heating roller 1 may be provided. If a safety switch that opens and closes based on the temperature detected by the temperature detecting element is connected in series with the power supply circuit 8 and the relay SSR to the power supply circuit to the resistance heating layer 12 shown in FIG. Does not work properly and the heating roller 1
Even when the temperature rises abnormally, the safety switch can shut off the power supply circuit before the heating roller 1 and its peripheral parts are thermally damaged. The temperature detecting element may be provided in contact with the outer peripheral surface of the heating roller 1. As the temperature detecting element, for example, a thermistor or a thermocouple can be adopted, and as a safety switch having a temperature detecting function, for example, a temperature fuse or a thermostat can be adopted.

As shown in FIG. 1, a release agent applying device 17 for preventing the toner from adhering to the surface of the heating roller 1 is disposed on the heating roller 1. A separation claw 6 is provided for separating the recording material to be wound around the heating roller 1 from the roller. The recording material conveying roller device 5 includes a driving roller 51 and a driven roller 52.

As partially shown in FIG.
A plurality of rollers 1 and driven rollers 52 are provided at predetermined intervals in a direction parallel to the rotation center axis of the heating roller 1, and the corresponding driving roller 51 and driven roller 52 are in contact with each other. Further, the lower guide plate G2 facing the drive roller 52
Is provided with a notch recess g2 in which the plurality of drive rollers 51 are loosely fitted, corresponding to each drive roller.

The plurality of drive rollers 51 are supported by a common shaft 511 and, as shown in FIG. 1, are driven to rotate counterclockwise in the figure by a motor M via a gear train GT2. Each of the driven rollers 52 is rotatably supported by a holding member 53 on a shaft 521, and is in contact with the driving roller 51 under pressure by a plate spring 54 formed integrally with the holding member 52. It follows and rotates.

The nip 50 between the driving roller 51 and the driven roller 52 is connected to the nip 10 between the heating roller 1 and the pressure roller 2.
0, that is, at a position higher than the nip portion 100 in this case, and the driven roller 52 is slightly shifted from the drive roller 51 in the recording material conveyance direction α. It is located in the position.
Due to such an arrangement relationship, the recording material S that has passed through the nip portion 100 between the heating roller 1 and the pressure roller 2 and curled upward (here, so-called face curled) with the heating roller 1 is driven by the driving roller 51. The sheet can be conveyed so as to be bent back to the opposite side (lower side) at the nip portion 50 with the roller 52.

A holding member 53 for holding each driven roller 52
Is formed integrally with a leaf spring 54 by punching and bending a sheet metal having spring elasticity. Each holding member 53 has an inverted U shape as shown in FIGS.
There is a pair of portions 53a which are shaped like a letter and descend along both side surfaces of the driven roller 52, and the driven roller 52 is supported on the shaft 521 there. Each lower portion 53a has a recording material guide 530 at the lower end. Each guide section 53
0 is formed by an edge 531 obtained by bending the lower end of the descending portion 53a outward and drawing. The guide portion 530 faces the drive roller 51 and has a curved surface 5 having a smaller diameter than the driven roller 52 when viewed from the side (as viewed from the side).
31a and an inclined surface 531b extending to the upstream side in the recording material conveyance direction continuously from the curved surface.

A leaf spring 54 extending integrally from the holding member 53 extends toward the release material applying device 17 and is cantilevered at a spring end 541 (see FIG. 3).
According to the fixing device described above, the fixing of the toner image on the recording material holding the unfixed toner image is performed as follows. That is, the relay SSR is closed by the control unit CTR, and power is supplied to the resistance heating layer 12 from the power supply 8 via the power supply member 16 and the power reception member 15 and the like. Is heated from the inner peripheral surface side. By using a resistance heating element as a heating source of the heating roller 1, the temperature of the heating roller 1 quickly rises. At this time, energization control is performed based on the temperature of the heating roller 1 detected by the thermistor TH, and the heating roller 1 is maintained at a predetermined fixing temperature. Then, the heating roller 1 is rotated in a predetermined direction by the motor M via the gear train GT1, and the recording material is passed between the heating roller 1 having the fixing temperature and the pressing roller 2 pressed toward the fixing roller. Thereby, the unfixed toner image on the recording material is fixed under heat and pressure.

In the recording material conveying roller device 5, the driving roller 51 is also driven to rotate by the motor M, and the roller 53 rotates following the driving roller 51. Recording material S exiting from nip 100 between heating roller 1 and pressure roller 2
Is that even if the leading end S1 is face-curled, the leading end S1 of the recording material contacts the guide portion 530 of the driven roller holding member 53 and is guided in a direction in which the curl is bent back while the recording material is bent. The roller is smoothly guided to the nip portion 50 of the driving roller 51 and the driven roller 52 without being broken, and is smoothly discharged by the rotation of the roller and the roller.

In the recording material conveying roller device 5, the guide portion 530 is not provided separately from the device 5,
Since the driven roller holding member 53 is used and provided there, the device 5, and thus the entire fixing device, can be simplified, reduced in size, and made compact. FIG. 6 shows another example of a driven roller holding member provided with a guide portion.

The holding member 55 shown in FIG. 6 comprises a main body 55A and a guide 550. The main body 55A is formed integrally with the leaf spring 54 by punching and bending a sheet metal having spring elasticity. The main body 55A is shown in FIG.
And the like, but the guide portion 550 is formed separately from the main body, and the main body 55A
The driven roller 52 is engaged with a lower end portion of a portion descending along each side surface of the driven roller 52. The guide portion 550 also faces the drive roller 51, and the driven roller 52 is viewed from the side (when viewed from the side).
A curved surface 551 having a smaller diameter arc shape and a slope 552 extending to the upstream side in the recording material conveyance direction continuously from the curved surface are included.

Although the example in which the recording material conveying roller device 5 is employed in the fixing device has been described above, the recording material conveying roller device of the present invention can be applied to other portions.

[0032]

According to the present invention, it is possible to provide a simple and compact recording material conveying roller device capable of smoothly receiving and discharging the fed recording material without damaging it.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view (a schematic cross-sectional view taken along a rotation center axis of a roller) of a fixing device employing a recording material conveying roller device according to an embodiment of the present invention.

FIG. 2 is another schematic cross-sectional view of the fixing device shown in FIG. 1 (a schematic cross-sectional view along a roller rotation center axis direction).

FIG. 3 is a schematic perspective view of a part of the recording material conveying roller device shown in FIG.

FIG. 4 is a side view of a main part of the recording material conveying roller device.

FIG. 5 is a schematic diagram of an energization circuit for a resistance heating layer and a control circuit for performing energization control.

FIG. 6A is a side view of another example of a driven roller and its holding member in a recording material conveying roller device, and FIG.
FIG.

[Explanation of symbols]

5 Recording Material Conveying Roller Device 51 Driving Roller 52 Followed Roller 53, 55 Followed Roller Holding Member 530, 550 Guide 531 Edge 531a, 551 Curved Surface 531b, 552 Guide Side Curved Surface 531b, 552 Slope of Guide

Claims (5)

[Claims] 1. A recording material transport roller device comprising a driving roller and a driven roller facing the driving roller, the recording material transporting roller device for transporting a fed recording material while nipping the recording material between the driving roller and the driven roller. The roller is rotatably supported by a holding member, and the holding member includes a guide portion that guides the recording material between the drive roller and the driven roller, and the guide portion faces the drive roller. A recording material transport roller device comprising: a curved surface having an arc shape smaller in diameter than the driven roller; and a slope extending to the upstream side in the recording material transport direction continuously from the curved surface. 2. The holding member is formed of a sheet metal.
The guide portion faces the drive roller of the holding member,
2. The recording material transporting roller device according to claim 1, wherein the recording material transporting roller device is formed at an edge portion subjected to bending drawing. 3. The recording material conveying roller device according to claim 1, wherein said holding member includes a main body formed of sheet metal, and said guide formed separately from said main body and mounted on said main body. 4. The driven roller is pressed against the drive roller by a leaf spring, and the leaf spring is formed integrally with the holding member from the sheet metal.
A recording material conveying roller device according to claim 1. 5. The recording material conveying roller device according to claim 1, wherein the recording material conveying roller device is disposed downstream of the fixing roller pair in the fixing device in the recording material conveying direction.