JPH11327346A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device capable of preventing a web from being carelessly paid out at the time of jamming, and making recording paper possible to be released either on the upstream side or on the downstream side, in a state that the web unit is not mounted. SOLUTION: When the recording paper 4 is pulled in the direction of the arrow K in the state of mounting the web unit, a fixing roller 2 is about to rotate in the direction of the arrow L, however the rotary force in the direction shown by the arrow I is applied to the plate 16 in company with the rotation of a gear 14, the gear 17 is brought into the state of engaging with the gear 13, and the rotation is not permitted. However, in the state of detaching the web unit, the plate 16 is brought into contact with a lever 18 being in a position raised by the elastic force of the spring 19 and stopped, and the gear 17 brought into the position separated from the gear 13, and hence the gear 17 is made possible to be freely rotated. Therefore, the jam of the recording paper 4 is made possible to release toward the upstream side of a transporting path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for a laser printer or the like using a web as a release agent applying member or a roller cleaning member.

[0002]

2. Description of the Related Art In a fixing device using a fixing roller for a laser printer or the like, it is widely used to apply a release agent such as silicone oil to the fixing roller to prevent the toner from being offset to the heat fixing roller. Have been. Especially,
In a full-color image forming apparatus that performs printing by mixing toners of a plurality of colors, the fixing roller needs to have a very high releasability. For this reason, a large amount of release agent is usually applied to the fixing roller.

Hereinafter, a conventional fixing device for a full-color image forming apparatus will be described. Forming a latent image of an image on a photoreceptor belt with each color separation signal of image data, coloring the latent image with a color toner to form a toner image, and transferring the toner image to a recording material is one for each color. By repeating this process, a full-color image is formed on the recording material, and the unfixed toner image formed on the recording material is fixed by a fixing device provided in the image forming apparatus.

FIG. 5 is a schematic sectional view of a conventional fixing device.
The fixing device includes a roller-shaped fixing roller 2 and a fixing roller 2.
A pressure roller 3 that rotates while pinching the recording paper 4;
The fixing roller 2 includes a web unit 5 having a built-in web 6 for applying a silicone oil as a release agent. The web unit 5 cleans toner adhered to the surface of the fixing roller 2 simultaneously with the application of the silicone oil.

[0005] The fixing roller 2 has an elastic layer made of a high-temperature vulcanizing type (hereinafter abbreviated as HTV) silicone rubber, an oil-resistant layer made of fluoro rubber, and an ordinary temperature-applied layer on an aluminum core serving as a base material. An offset prevention layer made of a vulcanization type (hereinafter referred to as RTV) silicone rubber is sequentially formed. The outer diameter of the fixing roller 2 is φ40 mm. On the pressure roller 3, an elastic layer made of HTV silicone rubber and a resin layer made of fluororesin are sequentially formed on an aluminum cored bar.
Like the fixing roller 2, the outer diameter is 40 mm.

A halogen heater is disposed in the core of the fixing roller 2 and the core of the pressure roller 3, and the temperature of the fixing roller 2 is detected by a thermistor in contact with the fixing roller 2.
The halogen heater is controlled to be turned on and off to maintain the temperature of the fixing roller 2 at about 165 ° C.

The web unit 5 includes a web roll 7 on which a web 6 is wound, and a winding roller 8 for winding the web 6.
It is composed of The web 6 is impregnated with a silicone oil having a viscosity of 500 cS, and has a structure in which the pressing roller 9 presses the web 6 against the fixing roller 2. The web 6 is driven by a drive motor to drive the gears 10, 11,
By driving the take-up roller 8 via
The silicone oil that has been fed by a fixed amount and impregnated in the web 6 is applied to the offset prevention layer of the fixing roller 2. The take-up roller 8 is provided with a one-way clutch,
The web 6 is configured to rotate only in the winding direction. The web unit 5 attaches the silicone oil to the fixing roller 2 and removes the toner attached to the offset prevention layer on the fixing roller 2 by attaching the toner to the web 6.

The fixing roller 2 is driven via gears 14 and 15 by a driving gear 13 connected to a driving motor. The chassis 1 holds the fixing roller 2, the pressure roller 3, the gears 10, 11, 14 and 15, and also holds the web unit 5 detachably in the direction indicated by the arrow A.

The operation of the conventional fixing device configured as described above will be described below.

When the drive gear 13 rotates in the direction shown by arrow B, the gear 14 rotates in the direction shown by arrow C,
The fixing roller 2 and the pressure roller 3 rotate in the directions indicated by arrows D and E, respectively, and the recording paper 4 carrying a plurality of toner images formed of toners of a plurality of colors is stacked on the fixing roller 2 and the pressure roller 3. By moving the toner images in the direction indicated by arrow F while holding them together, the stacked toner images are heat-fixed while being mixed on the recording paper 4 to form a full-color image on the recording paper 4. At this time, the toner adhered to the fixing roller 2 from the recording paper 4 adheres to the web 6 wound by the winding roller 8 by a fixed amount in synchronization with the rotation of the fixing roller 2, so that the fixing roller 2 The surface is cleaned.

[0011]

However, in the above-described conventional configuration, when the recording paper 4 is jammed in the transport path, the recording paper 4 is moved in the direction opposite to the direction indicated by the arrow F, that is, from the upstream side of the transport path. When the fixing roller 2 is to be removed, the fixing roller 2 rotates in the direction opposite to the direction indicated by the arrow D,
At this time, the web 6 sandwiched between the fixing roller 2 and the pressing roller 9 follows the rotation of the fixing roller 2 and the web roll 7.
It will be more extended. At this time, the winding roller 8
Has stopped, the web 6 becomes slack between the take-up roller 8 and the web roller 7, and there is a problem that the application and cleaning of the silicone oil may be hindered thereafter. If the slack amount of the web 6 is excessive, the slack portion of the web 6 is caught between the fixing roller 2 and the pressure roller 3, and the web 6 is unwound in large quantities, and the unwound web 6 is wasted without being used. In some cases.

Accordingly, the present invention prevents the web from being carelessly fed out in the event of a jam, and allows the recording paper to be released both upstream and downstream when the web unit is not mounted. It is an object of the present invention to provide a fixing device that performs the fixing.

[0013]

According to the present invention, there is provided a fixing roller, a pressure roller which sandwiches a recording medium between the fixing roller and rotates in conjunction with the fixing roller, a web containing a release agent, A web roll for winding the web, a winding roller for winding the web from the web roll in conjunction with rotation of at least one of the fixing roller or the pressure roller, and holding the web roll and the winding roll. A detachable web unit for bringing the web into close contact with at least one of the fixing roller or the pressure roller; and the fixing roller or the fixing roller when the fixing roller or the pressure roller rotates in a direction opposite to the rotation direction during printing. A clutch for preventing the rotation of the pressure roller, and releasing the blocking operation of the clutch when the web unit is separated. It provided the means.

With this configuration, it is possible to prevent the web from being carelessly fed out in the event of a paper jam, and to release the recording paper both upstream and downstream when the web unit is not mounted. A fixing device can be realized.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a fixing roller, a pressure roller which holds a recording medium between the fixing roller and rotates in conjunction with the fixing roller, a web containing a release agent, and a web. A web roll to be wound, a winding roller for winding the web from the web roll in conjunction with the rotation of at least one of the fixing roller or the pressure roller, and holding the web roll and the winding roll; A detachable web unit for bringing the web into close contact with at least one of the fixing roller and the pressure roller, and the fixing roller or the pressure roller when the fixing roller or the pressure roller rotates in a direction opposite to the rotation direction during printing. A clutch for preventing rotation of the pressure roller, and releasing means for releasing the blocking operation of the clutch when the web unit is separated. Digits.

With this configuration, when the recording paper jams in the transport path, the recording paper can be removed only in the forward direction with the web unit attached, and the recording paper can be removed in the forward direction with the web unit removed. In addition, it can be removed in the opposite direction.

Hereinafter, a fixing device according to an embodiment of the present invention will be described. FIGS. 1, 2, 3 and 4 are schematic sectional views of a fixing device according to an embodiment of the present invention. In FIG. 1, components denoted by the same reference numerals as those of the fixing device of the related art are the same components, and thus description thereof is omitted. In FIG. 1, a chassis 1 holds gears 10 and 11, a fixing roller 2, a pressure roller 3, driving gears 13 and 14, and the like. The chassis 1 is provided with a protrusion 1a. The plate 16 is rotatably held coaxially with the gear 14, and rotatably holds the gear 17 engaged with the gear 14. Further, the chassis 1 holds the lever 18 via a spring 19. Web unit 5 is chassis 1
, The lever 18 is pressed down by the web unit 5.

Next, the operation of the fixing device will be described.
First, when printing is performed, as in the conventional technique, the driving gear 1 is used.
3 rotates in the direction indicated by the arrow B, thereby causing the gear 14 to rotate.
Rotates in the direction indicated by the arrow C, the fixing roller 2 and the pressure roller 3 rotate in the directions indicated by the arrows D and E, respectively, and the recording paper 4 is pinched between the fixing roller 2 and the pressure roller 3 while the arrow By moving the toner image in the direction indicated by F, the toner image is heat-fixed while being mixed on the recording paper 4, and a full-color image is formed on the recording paper 4. At this time, with the rotation of the gear 14, the plate 16 receives a rotational force in the direction shown by the arrow G due to the rotational resistance of the gear 14 and the gear 17, and stops in a state of contact with the projection 1a. For this reason, the gear 17 is rotating freely.

Next, the case where the recording paper 4 is released toward the downstream side when the recording paper 4 is jammed in the fixing device or in a conveying path (not shown) upstream thereof during printing will be described. . By pulling the jammed recording paper 4 in the direction indicated by arrow F, the fixing roller 2 and the pressure roller 3 rotate in the directions indicated by arrows D and E, respectively.
The plate 16 receives a rotational force in the direction shown by the arrow G in accordance with the rotation of the fixing roller 2 and the gear 15, so that the plate 16 stops in a state of contact with the projection 1 a as in the case of printing.
7 can rotate freely. At this time, the rotation of the fixing roller 2 causes the web 6 to receive a force in a direction opposite to that in printing,
Since the winding roller 8 rotates only in the winding direction, the fixing roller 2 rotates while sliding on the web 6.

Next, a case where the recording paper 4 is to be released toward the upstream side of the conveyance path will be described with reference to FIG. When the recording paper 4 is pulled upstream from the fixing device in the direction of arrow K, the fixing roller 2 and the pressure roller 3 try to rotate in the directions indicated by arrows L and M, respectively. Accordingly, the gear 14 tries to rotate in the direction indicated by the arrow N. However, with the rotation of the gear 14, a rotational force is applied to the plate 16 in the direction indicated by the arrow I, and the gear 17 meshes with the gear 13. Stop. Since the gears 13, 16 and 17 are meshed with each other, these gears cannot be rotated. Therefore, the fixing roller 2 and the pressure roller 3 cannot be rotated, and the rotation of the fixing roller 2 prevents the web 6 from being carelessly fed.

Next, a case where the jam of the recording paper 4 is released toward the downstream side with the web unit 5 removed will be described. In FIG. 3, the lever 18 stops at a position raised by the elastic force of the spring 19 due to the separation of the web unit 5 (arrow J). Record paper 4 with arrow F
When the fixing roller 2 and the pressure roller 3 are pulled in the directions indicated by the arrows, the fixing roller 2 and the pressure roller 3 rotate in the directions indicated by arrows D and E, respectively. At this time, since the plate 16 receives a rotational force in the direction shown by the arrow G according to the rotation of the fixing roller 2 and the gear 15, the plate 16 stops in contact with the projection 1a as in the printing, and the gear 17 is free. Can rotate.

Next, a case will be described in which the jam of the recording paper 4 is released toward the upstream side of the transport path with the web unit 5 removed. In FIG. 4, when the recording paper 4 is pulled upstream of the fixing device in the direction of arrow K, the fixing roller 2 and the pressure roller 3 rotate in the directions indicated by arrows L and M, respectively. Accordingly, the gear 14 rotates in the direction indicated by the arrow N. With the rotation of the gear 14, the plate 16
Is subjected to a rotational force in the direction indicated by arrow I,
Stops in contact with the lever 18 at the raised position. At this time, since the gear 17 is separated from the gear 13, the gear 17 can rotate freely. Therefore, with the web unit 5 removed, the jam of the recording paper 4 can be released toward the upstream side of the transport path.

[0023]

As described above, the fixing apparatus according to the present invention prevents the web from being inadvertently fed out by preventing the jammed recording paper from being released upstream when the web unit is mounted. However, when the web unit is not mounted, the recording paper can be released both upstream and downstream.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a fixing device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a fixing device according to an embodiment of the present invention.

FIG. 3 is a schematic sectional view of a fixing device according to an embodiment of the present invention.

FIG. 4 is a schematic sectional view of a fixing device according to an embodiment of the present invention.

FIG. 5 is a schematic sectional view of a conventional fixing device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chassis 2 Fixing roller 3 Pressure roller 4 Recording paper 5 Web unit 6 Web 7 Web roll 8 Take-up roller 9 Press roller 14 Gear 16 Plate 17 Gear 18 Lever 19 Spring

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroyuki Noda 1006 Kadoma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] An image forming apparatus comprising: a fixing roller; a pressure roller that sandwiches a recording medium between the fixing roller and rotates in conjunction with the fixing roller; a web containing a release agent; and a web roll that winds the web. A winding roller that winds the web from the web roll in conjunction with the rotation of at least one of the fixing roller and the pressure roller; and a holding roller that holds the web roll and the winding roll. A detachable web unit for adhering the web to at least one of the pressure rollers, and preventing rotation of the fixing roller or the pressure roller when the fixing roller or the pressure roller rotates in a direction opposite to a rotation direction during printing. And a release means for releasing the blocking operation of the clutch when the web unit is separated. That the fixing device.