JPH03211579A - Fusing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device for fixing an unfixed developer image onto a transfer material as a permanent image.

[Prior Art] Conventionally, as a method of applying a release agent used in a fixing device, there is, for example, the method shown in FIG. 6(A). In the fixing device shown in FIG. 6(A), a transfer material carrying an unfixed developer image (hereinafter referred to as an unfixed toner image) is brought into pressure contact between a fixing roller l and a pressure roller 2 (hereinafter referred to as a nip part). The image is fixed by being conveyed under pressure. The fixing roller l is provided with a heater 3 serving as a heat source inside, and a fluororesin that is stable even at high temperatures and has high mold release properties is coated around a metal core roller 4 as a release layer 5. A pressure roller 2 is disposed below the fixing roller 1 in pressure contact with the fixing roller 1, and the pressure roller 2 has a silicone rubber layer 6 on its outer layer. The silicone rubber M6 has sufficient elasticity, heat resistance, and durability to form the nip portion between the fixing roller 1 and the pressure roller 2, and has high mold releasability. Further, a release agent coating member 7 is disposed above the fixing roller 1 in contact with the fixing roller l, and a silicone oil reservoir 8 is provided above the release agent coating member 7. There is. Furthermore, a meter link plate 9 is disposed in contact with the fixing roller 1 on the downstream side in the rotational direction of the fixing roller l with respect to the contact portion between the release agent applying member 7 and the fixing roller 1. . When the fixing roller I rotates, silicone oil as a release agent supplied onto the fixing roller l by the release agent application member 7 is spread by the metering blade 9 and the nip portion to form a thin film on the fixing roller 1. This further improves the releasability of the fixing roller 1, thereby reducing offset of the toner image onto the surface of the fixing roller 1.

[Problem to be solved by the invention] However, since the silicone rubber layer 6 on the outer layer of the pressure roller 2 and silicone oil have a high affinity, the above problem occurs if the amount of silicone oil spread on the meter link plate 9 is not sufficient. At the nip portion, the silicone oil on the fixing roller 1 is transferred to the pressure roller 2, and the silicone oil on the fixing roller 1 tends to be insufficient, which tends to cause offset. Therefore, in order to prevent the occurrence of this offset, it is necessary to increase the amount of oil supplied to the fixing roller 1, and for this reason, it is necessary to replenish silicone oil or replace the application member frequently at short intervals. As a result, when the capacity of the oil reservoir 8 is increased or when the metering blade 9 is used for a long period of time, toner accumulates at the metering blade 9, which requires cleaning from time to time. Therefore, the method shown in FIG. 6(B) was proposed.

The application member 7 shown in FIG. 6(B) is composed of a felt 11 in which a support member IO is impregnated with silicone oil, and is used to apply oil and clean the fixing roller 1 at the same time. Although this method is an effective device because it is simple, inexpensive, and allows oil application and cleaning to be performed at the same time, the absolute amount of oil contained in the felt 11 is small, causing an oil shortage at an early stage. In addition, the portion of the felt 11 that comes into contact with the fixing roller becomes dirty, which also causes early cleaning failure.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a fixing device that can be used for a long period of time and performs good fixing without offset.

[Means for Solving the Problems] According to the present invention, the above object is achieved by: a fixing roller having a heat source inside and rotatably disposed; and a pressurizing roller disposed in pressure contact with the fixing roller. The fixing device has a roller, and uses the fixing roller and the pressure roller to convey a transfer material carrying an unfixed developer image under pressure to perform fixing, and the fixing device contacts the fixing roller to release the transfer material. The fixing device includes a release agent application member for applying a release agent, and a drive means that allows the release agent application member to move toward and away from the fixing roller, and a drive means for bringing the release agent application member toward and away from the roller. a control means for the drive means for controlling the operation, when the release agent application member comes into contact with the fixing roller, a surface of the release agent application member facing the fixing roller is exposed; Furthermore, this is achieved by providing a shielding member that opens and closes as the E foot joint type agent applying member approaches and separates so as to cover the surface during separation.

[Function] The present invention provides a drive means for a release agent application member that allows the release agent application member to move toward and away from a fixing roller or a pressure roller, and a means for driving the release agent application member to move the release agent application member toward and away from the fixing roller or pressure roller. and control means for the drive means for controlling the approaching and separating operations. The control means causes the release agent application member to contact one of the rollers to apply the release agent, and after the contact, the release agent application member is brought into contact with one of the rollers.
I: Separate from the roller. In this case, the present invention is provided with a shielding member that can be opened and closed, and the shielding member exposes the surface of the release agent application member facing the fixing roller when they are in contact with each other, and covers the surface when they are separated. Therefore, the release agent of the release agent coating member is consumed only when it comes into contact with the roller, and the release agent is only brought into contact with the roller when fixing is performed. Further, when separating, the surface of the L-legged agent applying member is covered with the shielding member, thereby preventing the release agent from evaporating due to the heat of the fixing roller. As a result, wasteful consumption of mold release agent can be suppressed.

"Embodiment" An embodiment of the present invention will be described with reference to FIGS. 1 to 5 of the accompanying drawings. Note that the same reference numerals are given to the same parts as those of the conventional device shown in FIGS. 6(A) and 6(B), and the explanation thereof will be omitted.

In this embodiment, the fluororesin release layer of the fixing roller l is made of PTFE (polytetrafluoroethylene), and the surface 12 of the silicone rubber layer 6 of the pressure roller 2 is made of PTFE (polytetrafluoroethylene).
The device is different from the conventional device shown in FIGS. 6(A) and 6(B) in that it is coated with a fluororesin to improve mold releasability. Furthermore, in the present embodiment, the release agent application member 7 is a roller body that is in contact with the fixing roller l and is freely rotatable as a result of rotation. It has a felt layer 14 impregnated with a molding agent.

The release agent application roller 7, which is the release agent application member, is rotatably held in a holder 15 having an opening at the bottom, and the contact portion of the release agent application roller 7 with respect to the fixing roller l is located at the opening. It is appearing from. The holder 15 has a guide 17 rotatably arranged around a shaft 16.
When the guide 17 rotates, the releasing agent application roller 7 is brought into contact with and separated from the roller 7. Further, the halter 15 is urged downward by a spring 18 within the guide 17, so that the contact pressure of the release agent application roller 7 against the fixing roller 1 can be adjusted. The shaft 16 side of the guide 17 is urged in the direction of arrow A by a tension spring 19, and moves the release agent application roller 7 to a position where it does not come into contact with the fixing roller 1. An arm portion 20 is formed at the end of the guide 17 opposite to the shaft 16, and the arm portion 20 comes into contact with a lever 22 connected to a solenoid 21 serving as a driving means.
ing. In the state shown in FIG. 1, the lever 22 has a distal end extending in a direction perpendicular to the drawing, and is rotatably disposed about a shaft 23. When the solenoid 21 is energized, the lever 22 rotates, and the tip of the lever 22 pushes down the arm 20 in the direction of arrow B. The energization of the solenoid 21 is controlled by a DC controller 24 serving as a control means. Therefore, by rotating the guide 17, it is possible to control the movement of the release agent application roller 7 towards and away from the fixing roller l. However, the above guide 1
The surface of the contact portion of the release agent application roller 7 that is exposed through the opening of the release agent application roller 7 is covered by a shutter 25 that is a shielding member and is disposed rotatably around the axis of the release agent application roller 7. There is. The shutter Z5 has one end connected to the guide 17.
and is urged in the direction of arrow C by a coil spring 26 whose other end is fixed to the side wall of the shutter 25, so that the releasing agent applying roller 7 is not in contact with the fixing roller l. In some cases, the surface of the contact portion is covered.

However, the arrow B is centered around the guide 17 or the shaft 16.
When it starts to rotate in the direction, as shown in FIG. The surface of the abutting portion of the fixing roller 1 is exposed and can come into contact with the fixing roller l.

As described above, the contact and separation operations of the release agent application roller 7 in the apparatus of this embodiment are controlled by the DC controller 24, and are driven at predetermined timings set in advance. For example, when the device of this embodiment is used in a copying machine, the release agent application roller 7 is used during non-copying operations.
The solenoid 21 is driven so that it does not come into contact with the fixing roller l, and when the solenoid 21 is in contact with the fixing roller l, the release agent applying roller 7 is applied before the transfer material reaches the fixing roller and the pressure roller.
The solenoid 21 is driven so that the release agent coating roller 7 is brought into contact with the fixing roller 1 and the release agent coating is completed outside one rotation of the fixing roller 1, and then the release agent application roller 7 is brought out of contact with the fixing roller 1 again. In other words, only the minimum necessary amount of mold release agent should be applied. Therefore, the mold release agent can be applied over a long period of time without using a container for supplying the mold release agent. moreover.

Since the surface of the release agent application roller 7 is covered by the shutter 25 when the release agent application roller 7 is not in contact, the release agent is prevented from evaporating due to heat from the fixing roller.

(Experimental Example) Next, an experimental example conducted based on this example will be described. This experimental example was conducted under the following conditions.

The metal roller 4 of the fixing roller 1 has a wall thickness t = 2.5 mm.
It is a hollow cylindrical aluminum alloy core metal, and the mold release layer 5
The surface layer of the barrel is coated with a fluororesin PTFE (polytetrafluoroethylene) layer. A diameter of 321 Ill was used. Further, a halogen heater was used as the heater 3 serving as a heat source inside the heater.

The pressure roller 2 has a thickness t=5, Ol as an intermediate layer on the core metal.
silicone rubber layer 6, which is an elastic body, and PF on its surface 12.
A (copolymer of polytetrafluoroethylene resin and perchloroalkoxyethylene resin) with a thickness of 50 g
A tube-shaped fluororesin layer of 30 m in diameter was formed.

The release agent coating roller rough, which is a release agent coating member, has a silicone rubber layer 13 with a thickness t=4■■ as an intermediate layer, that is, an elastic layer, on a core metal, and a heat-resistant felt layer 13 with a thickness t on the surface layer.
A heat-resistant felt layer I4 having a thickness of 1.5 mm and a density of OJg/cm:l is coated and formed, and when the release agent application roller 7 comes into contact with the fixing roller l, it comes into contact with a relatively light load, and the roller is driven to rotate. It was configured to do so. The diameter is 21i
n was used. The heat-resistant felt layer 14 contains silicone oil with a viscosity of 10,000 cs and a release agent of about 11.0 cs.
It is impregnated uniformly in the longitudinal direction. The axial length of this release agent application roller rough is set to be longer than the nip length formed by the fixing roller and the pressure roller. This is because if it is too short, there will be a portion where oil is not supplied to the nip, and the fixing roller and pressure roller will be rotated slidingly without oil, which will easily cause damage to the rollers.

In this experimental example, the above-described fixing device was used in a copying machine. Next, using the timing charts of FIGS. 1 and 3, and FIGS. 4 and 5, control of the release agent application roller will be explained according to the operation of the copying machine during the experiment. Note that the operation shown in FIG. 3 is for continuous copying.

First, when the copying apparatus is stopped or on standby when it is capable of receiving copy signals, the release agent application roller 7 is in the first position.
As shown in the figure, it is in a non-contact state with the fixing roller. Furthermore, the photosensitive drum and fixing roller, which are latent image carriers, and the optical system are also stopped (denoted as off in Figure 3).Next, the photosensitive drum and fixing roller rotate at the same time as the copy signal is turned on (Figure 3). ). The purpose of rotating the fixing roller is to transfer the heat of the fixing roller to the pressure roller, and this is called pre-rotation.

After the previous rotation is completed, the optical system or the document table moves forward to read the document and expose an image signal onto the photosensitive drum. Thereafter, the electrostatic latent image formed by exposure is developed by a developing device and transferred to a transfer material. The transfer material carrying this unfixed visible image is conveyed to a fixing device by a conveyance system. The time point A when the release agent application roller starts contacting the fixing roller is set at least after the fixing roller has rotated.

This is because if it comes into contact with the fixing roller while it is stopped, excess oil will seep out or it will become a load for starting the rotation of the fixing roller. Also,
The above-mentioned contact start point A is a point at which the fixing roller can rotate at least once after the release agent coating roller comes into contact with the fixing roller before the transfer material enters the fixing roller. Such a point A
When a signal is input to the solenoid 21 from the DC controller 24, the iron core of the solenoid is attracted, the lever 22 rotates, and the arm portion 20 of the guide 17 is pushed. Then, the guide 17 begins to rotate counterclockwise as shown in FIG. 4, and the projection 24 comes into contact with the ridge 27 of the shutter 25.

Surto, shutter 25 begins to open. Furthermore lever 2
When the guide 17 is pushed by the roller 2, the release agent application roller 7 moves as shown in FIG. 5, and the shutter 25 is pushed by the protrusion 24 and rotates around the axis of the release agent application roller. The felt ff14 on the surface of the application roller comes into contact with the surface of the fixing roller.

Next, the separation operation start point B may be after the fixing roller has made one revolution from the start point A, or may be a state in which the transfer material has entered between the fixing roller and the pressure roller. This is because it is necessary to supply oil to the fixing roller at least before the transfer material enters to prevent offset.

When the solenoid is turned off at time B, the guide 17 begins to rotate clockwise due to the biasing force of the tension spring 19. Then, in conjunction with this, the shutter 25 rotates counterclockwise around the axis of the release agent application roller by the force of the coil spring 26, and returns to the position where it protects the felt layer on the surface of the release agent application roller. . The following operations are performed in the same manner. However, during the backward movement of the optical system after the final copy and during the backward rotation for cleaning, etc., the release agent application roller remains in non-contact and no oil is supplied. This is to prevent wasteful consumption of oil.

The oil in the felt layer 14 gradually oozes out when the felt layer moves in contact with the felt layer and is supplied to the fixing roller, so that the amount of oil decreases in proportion to the contact movement time (B-A). In other words, the shorter the contact operating time (B-A), the less oil seeps out and the longer the product can be used. Even for the fixing roller, if oil is present on the surface before it comes into contact with the transfer material, offset can be sufficiently prevented.

By controlling the contact and separation operations of the release agent application roller as described above, the life of the release agent application roller could be extended compared to a case where the release agent application roller is in constant contact. Moreover, by covering the surface of the release agent application roller with a shutter when it is not in contact with the roller, it blocks heat from the fixing roller and prevents the release agent from evaporating, so the release agent can be used for a long time without wasting the release agent. You can also use it.

[Effects of the Invention] As explained above, the present invention provides a drive means for a release agent application member that drives the release agent application member so as to be able to move toward and away from a fixing roller or a pressure roller, and a method for driving a release agent application member. a control means for the driving means for controlling the movement of the application member toward and away from the fixing roller or the pressure roller, the control means bringing the release agent application member into contact with the roller;
It is set so that they are then separated. Further, a shielding member is provided, which exposes the surface of the release agent application member when the contact is made, and covers the surface when the release agent is separated. Therefore, the mold release agent is not wasted and can be used for a long period of time. In addition, since the release agent 1m member contacts the roller only when necessary, the life of the release agent application member itself is extended, and toner does not accumulate in the contact area between the release agent application member and the roller. do not have. Furthermore, during the separation, the surface is covered with the shielding member, so that the release agent is not evaporated by the heat from the fixing roller.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a schematic configuration of the apparatus according to the first embodiment of the present invention, FIG. 2 is a perspective view of the area around the release agent coating member of the apparatus shown in FIG. 1, and FIG. A timing chart of the operation of the experimental example device. FIG. 4 is a cross-sectional view showing the state of the release agent applying member of the device shown in FIG. 1 in the middle of the contact operation, and FIG. 6(A) is a sectional view showing a schematic configuration of a conventional device, and FIG. 6(B) is a sectional view showing a schematic configuration of another conventional device. be. l...Fixing roller 2...Pressure roller

Claims (2)

[Claims] (1) It has a fixing roller that has a heat source inside and is rotatably disposed, and a pressure roller that is disposed in pressure contact with the fixing roller, and the fixing roller and the pressure roller fix the unfixed A fixing device that fixes a transfer material carrying a developer image by conveying it under pressure, and is equipped with a release agent applying member that comes into contact with the fixing roller to apply a release agent, the fixing device comprising: comprising a drive means for freely moving the release agent application member toward and away from the fixing roller, and a control means for the drive means for controlling the movement of the release agent application member toward and away from the roller; When the release agent coating member contacts the fixing roller, the surface of the release agent coating member facing the fixing roller is exposed, and when separated, the release agent coating member covers the surface. A fixing device comprising: a shielding member that opens and closes in accordance with the approaching and separating operations of the fixing device. (2) The release agent applying member is a roller body having a felt layer around a core metal, and is arranged to be driven to rotate when it comes into contact with a fixing roller or a pressure roller. The fixing device according to item (1).