JPH041688A - Fusing device - Google Patents

Abstract

PURPOSE:To simplify a driving mechanism and to uniformize the contact pressure of a coating roller uniform in the lengthwise direction by supporting the coating roller by a support member which has high rigidity and driving the support member only on one side. CONSTITUTION:When a solenoid is powered on to press a guide 17 by a lever 18, the guide 17 rotates around 17A as a center and the felt layer 9 of the oil coating roller 3 comes into contact with a fixing roller 1. At this time, a holder 14 rotates on a point 15 formed on a hook part 14-B and the uncut part of the guide 17 as a fulcrum and a leaf spring 20 deforms correspondingly, so that the oil coating roller 3 abuts on the fixing roller 1 with specific pressure. When the solenoid is powered off, the guide 17 rotates clockwise with the energizing force of a tensile spring 21 and the holder 14 and oil coating roller 3 leave the fixing roller 1 to return to their initial stand-by positions. Consequently, the contacting and leaving operation of the coating rotary body is performed by the easy mechanism and the lengthwise abutting pressure can be made uniform.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a fixing device that fixes an unfixed toner image carried on a recording material through a predetermined process as a permanent image on the recording material, and particularly relates to This invention relates to a mold release agent coating member.

[Prior Art] A fixing device for fixing a toner image on a recording material uses a heating roller 1 having a heater 4 inside as shown in FIG. 6, and a pressure roller 2 in pressure contact with the heating roller 1 to support the toner image. A heat roller fixing device that fixes a recording material by nipping and conveying it is popular.

In such a heat roller fixing device, a release agent is applied to the roller in order to prevent toner offset.

The conventional release agent applicator shown in FIG. 6 has a simple structure in which a felt 15 impregnated with silicone oil is supported by a support member 20 so as to be in contact with the fixing roller 1. Tonafutaru. This device is effective because it can apply oil as a mold release agent and clean the surface of the fixing roller 1 at the same time. The part that comes into contact with the fixing roller No. 15 is dirty,
Similarly, there was a drawback that cleaning failure occurred at an early stage and the felt 15 had to be replaced.

In response to this, a mold release 1Ijl coating roller as shown in FIG. 5 has been proposed. For example, there is a silicone rubber layer 8 as an intermediate layer on a core made of stainless steel, and a felt layer 9 made of heat-resistant felt is formed on the surface layer.
0cs of silicone oil is uniformly impregnated in the longitudinal direction of the release agent application roller. This release agent application roller contacts the fixing roller 1 and rotates as a result of the fixing roller 1.
Silicone oil is applied to the surface to prevent offset. However, even in the case of this mold release agent application roller, it must be replaced if the silicone oil impregnated into the felt layer runs out, but the roller has been devised to make the replacement interval as long as possible. As shown in FIG. 6, the release agent application roller 3 is configured to be able to freely come into contact with and separate from the fixing roller 1. As a result, the release agent application roller 3 is separated from the fixing roller 1 during the waiting period for copying or when fixing is not required, such as during pre-rotation of the copying operation. The amount of molding agent dispensed was reduced and the time required for replacement could be extended.

[Problems to be Solved by the Invention] However, although the contact and separation operations of the release agent application roller are driven at two locations at both ends of the application roller, there are problems in that the number of parts for driving increases; There is a problem in that the contact pressure of the application roller is uneven in the longitudinal direction due to the difference in accuracy between the drive parts on the front side and the back side.

[Means for Solving the Problems] The present invention, which solves the above-mentioned problems, includes a fixing rotating body for nipping and conveying a recording material and fixing it, and a releasing agent application device for applying a releasing agent to the fixing rotating body. A fixing device having a rotating body and a means for moving the coating rotating body toward and away from the fixing rotating body, which includes a support member having a large rigidity that rotatably supports the coating rotating body. However, the driving force of the approaching/separating means acts only on one side of the support member in the longitudinal direction of the coating rotor.

[Example] Hereinafter, the present invention will be described in detail based on coating drawings.

1 and 2 show a cross section of the fixing device of this embodiment.

FIG. 3 shows an oil application roller, its holding member (hereinafter referred to as a holder), and a guide member that is rotatably held on the fixing side plate and holds the oil application roller and its holder. .

In FIG. 1, reference numeral 1 denotes a fixing roller formed as a heating roller having a heating source inside, and has a wall thickness of, for example, 2.5 mm.
The roller has a diameter of approximately 32 mm and is made of a hollow cylindrical aluminum alloy whose surface is coated with a fluororesin PTFE (polytetralethylene) layer. The fixing roller 1 includes a pressure roller 2 and a fixing roller 1.
The fixing roller is pressed and rotated by the fixing roller so as to form a nip portion between the fixing roller and the fixing roller. The pressure roller 2 is
For example, as an intermediate layer on the core metal, the thickness is 5. A silicone rubber layer 6 which is an elastic body with a thickness of 0 mm and a tubular fluororesin layer 7 with a thickness of 50 μm are formed on the outer layer, and the outer diameter is 30 m.
m. Reference numeral 3 denotes an oil application roller for applying a release agent to the fixing roller 1, and a silicone rubber layer 8 with a thickness of about 4 mm, for example, and a heat-resistant felt layer are formed on the surface layer, respectively, on a core made of stainless steel. It has an outer diameter of φ21. The heat-resistant felt layer 9 is uniformly impregnated with about 15 g of silicone oil of 10,000 cs as a mold release agent in the longitudinal direction. This oil application roller is rotatably held by a holding member (holder) 14 at shaft portions 9A that protrude from both ends in the longitudinal direction. As shown in Figure 1, one of the bearings on both sides of the holder that holds the core metal of the oil application roller has a slit on the right side of the drawing, and this slit is used to hold the member. It is possible to spread due to the elasticity of
Push in and pull out the shaft 9A.

Therefore, the oil application roller can be attached and detached from this part.

As seen in FIG. 3, the holder is removably attached to a guide 17 having arm portions 17B and 17C at both ends, and when the arm portion 17B rotates about a rotation center 17A, 1° As shown in FIG. 2, it can freely approach and separate from the fixing roller 1.

As shown in FIG. 1, the holder 14 has a hook-shaped protrusion 14B on the opposite side (right side in the drawing) of a handle 14A for attaching and detaching from the main body, and the oil application roller comes into contact with the fixing roller. The structure is such that there is no risk of the oil application roller jumping out of the holder when the oil application roller is removed.

Furthermore, a pressure contact spring 20 is provided between the holder 14 and the guide 17 that holds it, in order to ensure a predetermined contact pressure when they come into contact. The spring 20 is a plate spring bent in the shape of a "<" in order to facilitate the attachment and detachment of the holder 14.

Further, the pressurizing point of the plate spring 20 is located at the midpoint between the hook-shaped protrusion and the contact portion of the oil application roller 3 and the fixing roller 1.

As shown in FIG. 2, the oil application roller receives a reaction force in the direction shown by the arrow a during contact. At this time, the hook 14B is in a state of being pressed against the cut-and-raised portion because a force is applied to the holder from the plate spring 20 at a position closer to the hook side. Therefore, the force acts on the oil application roller 3 including the holder in the direction of the arrow, but in order to prevent this, the holder 14 is provided with two hook-shaped protrusions (14-B). The cut-and-raised portion of the guide member 17 is hooked thereon.

As described above, the guide 17 is rotatable around the guide 17A, but is normally urged in the direction of separation by the spring 21 applied to the guide 17B.

On the other hand, a lever 18 driven by a solenoid comes into contact with the same side as 17B and rotates the guide 17.

Next, an image forming operation when the fixing device of this embodiment is used in an electrophotographic apparatus will be explained in order.

A photosensitive drum (not shown) and a fixing roller rotate simultaneously when a copy signal is turned on by a user. After the pre-rotation is completed, an optical system (not shown) begins to scan the original and exposes an image onto the photoreceptor drum. Thereafter, the developed image is transferred to a transfer material, which is a recording material, conveyed from a cassette or the like. The transfer material carrying the unfixed developed image is then sent to a fixing device by a conveyance system.

At this time, at least at a certain point when the fixing roller starts rotating and the transfer material does not enter the nip formed by the fixing roller and the pressure roller, a signal is sent from the DC controller 12, the solenoid is energized, and the iron core is The lever 18 rotates due to the suction and pushes the end of the guide 17.

When the guide 17 is pushed by the lever 18, the guide 1
7 rotates counterclockwise around 17A until it hits the stopper. Then, the felt layer 9 of the oil application roller 3 comes into contact with the fixing roller 1. At this time, the holder 14 rotates about a point 15 formed by cutting and bending the hook portion 14-B and the guide 17 as a fulcrum. Then, the relative position of the holder 14 with respect to the guide 17 changes, the leaf spring 20 deforms accordingly, and the oil application roller comes into contact with the fixing roller with a predetermined pressure.

After a certain period of time after the oil application roller 3 contacts the fixing roller 1, when the power to the solenoid is turned off, the guide 17 rotates clockwise due to the biasing force of the tension spring 21. The holder 14 and the oil application roller 3 fixed to the guide 17 are the fixing roller 1.
and return to the original standby position.

The above is the movement of the fixing device during the image forming operation.

In this way, according to this embodiment, the coating roller is supported by a highly rigid support member, and by driving this support member only on one side, the coating roller elastically pressed by the support member is transferred to the fixing roller. They are separated from each other.

For this reason, the drive mechanism is simplified and the contact pressure of the coating roller can be obtained uniformly in the longitudinal direction.

Furthermore, since the fixed end of the leaf spring 20 is arranged near the rotation center 17A of the holding guide 17 when viewed in cross section, the reaction force of the force that presses the oil application roller 3 against the fixing roller 1 is applied to this fixed end. However, since the force does not turn the holding guide 17, the pressing force can be further stabilized.

Although the embodiments of the present invention have been described using a roller-shaped rotating body, it can also be applied to a belt-shaped body.

[Effects] As explained above, according to the present invention, it is possible to move the coating rotating body toward and away from the coating member with a simple mechanism, and to apply uniform contact pressure in the longitudinal direction.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of the fixing interior of the embodiment of the present invention, FIG. 3 is a partial perspective view of a fixing device according to an embodiment of the present invention; FIG. 4 and FIG. 5 are sectional views of a conventional fixing device, respectively. FIG. 6(a) is a sectional view showing the contact state of the application roller; FIG. 6 (b is a cross-sectional view showing the state of the application roller between the paths; 1...Heating roller 2...Pressure roller 3... Application roller 14...Holder 17...Holding guide

Claims (3)

[Claims] (1) A fixing rotary body that nip and conveys the recording material and fixes it, a release agent application rotary body that applies a release agent to this fixing rotary body, and a fixing rotary body that applies a release agent to this fixing rotary body. A fixing device having a contact/separation means for bringing the application rotor into and out of contact with the body, the fixing device having a support member having high rigidity that rotatably supports the application rotor, and the driving force of the contact and separation means is applied to the application rotor. A fixing device that acts only on one side of a support member in the longitudinal direction of the fixing device. (2) The fixing device according to claim 1, wherein the driving force when the coating rotary body contacts and the driving force when separating the coating rotary body act on the same side of the support member. (3) The fixing device according to claim 1 or 2, wherein the coating rotor is rotated as a result of the fixing rotor.