JPH03211581A - Fixing device - Google Patents

Abstract

PURPOSE:To make the distribution of releasing agent discharge in the axial (longitudinal) direction of a fixing roller uniform by allowing a releasing agent applying member to abut on the fixing roller by gravity in a fixing device where the releasing agent applying member freely contacts with and separates from the fixing roller. CONSTITUTION:When a guide 17 is turned by an arm part 17B, the releasing agent applying member 9 whose shaft part exists on the bottom of a long hole by gravity moves and the relative position between the releasing agent applying roller 9 and a holder 14 is changed as soon as it starts to contact with the fixing roller 1. The center of the roller 9 moves along the axial line of the oval hole of the holder 14 and is positioned near the center of the hole. Since the long hole 16A of a bearing part 16 coincides with the moving direction of the shaft part of the roller 9, in such a case, the shaft part smoothly acts with almost no friction between the shaft part and the side of the long hole. Therefore, the contact of the roller 9 with the roller 1 is completed in a uniform state in the axial direction. Thus, the contact or non-contact action is executed while the distribution of the releasing agent discharge is kept 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 The present invention relates to the release agent coating member.

[Prior Art] A heat roller fixing device, which is a typical example of a conventional fixing device having a release agent applying means, will be described.

Such a heat roller fixing device has a configuration shown in FIG. 3(A). That is, the recording material carrying the unfixed toner image T formed through a predetermined process is fixed by passing through the pressure contact portion between the fixing roller 1 and the pressure roller 2 (the tab portion).

The fixing roller 1 is provided with a heating source 4 inside the metal roller, and the periphery of the metal roller is coated with a fluororesin that is stable even at high temperatures and has high mold releasability as a release layer. On the other hand, the pressure roller has an outer layer made of a silicone rubber layer that has sufficient elasticity, heat resistance, and durability to form the nip portion, and also has high mold releasability. The fixing roller 1 is configured to be supplied with silicone oil. The heat roller fixing device shown in FIG. 3(A) is configured such that silicone oil is constantly supplied only to the fixing roller 1, and a silicone oil reservoir 19 is provided at the L portion, and a release agent coating member 18 is provided. Fixing roller i-H
As the fixing roller l rotates, the silicone oil supplied to the fixing roller l is spread at the metering flade 13 and the nip portion arranged in contact with the fixing roller l, forming a thin film of the release agent on the fixing roller l. do. This further improves the releasability of the fixing roller 1, thereby preventing the toner image from being offset on the surface of the fixing roller 1.

However, since the silicone rubber of the outer layer of the pressure roller 2 used in this heat roller fixing device has a high affinity with silicone oil, if the amount of silicone oil spread by the meter link flade 13 is not sufficient, the nip At this point, 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 offset in this device, it is necessary to increase the amount of oil supplied to the fixing roller l, and for this purpose, it is necessary to replenish silicone oil or replace the application member frequently by shortening the interval. No. As a result, the oil tank capacity, etc. must be increased, and when used for a long time, the metering rate 1
Toner accumulated in the contact area of No. 3, and I had to clean it from time to time.

The device shown in FIG. 3(B) simultaneously applies oil and cleans the fixing roller l, and the applicator member 14
is composed of a support member 20 and a felt 15 impregnated with silicone oil. Although this device is effective because it is simple, inexpensive, and can perform oil application and cleaning at the same time, the absolute amount of oil contained in the felt 15 is small, causing an oil shortage at an early stage. Also,
The disadvantage is that the portion of the felt I5 that comes into contact with the fixing roller gets dirty, leading to early cleaning failures.

In contrast to the type that is in constant contact with the fixing roller, a release agent application member disposed near the fixing roller or pressure roller as shown in FIGS. 4(A) and 4(B) is used.
Immediately before the recording material carrying the unfixed toner image passes between the rotating fixing roller and the pressure roller, a release agent coating member is brought into contact with the fixing roller or the pressure roller for a predetermined period of time, and then separated. Measures are also being taken.

By carrying out the contact/non-contact operation in this way, the life of the release agent coating roller was extended compared to the type of roller that is in constant contact as shown in FIG.

U Problems to be Solved by the Invention] As described above, a longer life has been achieved by causing the release agent application member to perform contact/non-contact operations. However, since the conventional contact #1 mechanism of the release agent applying member has a structure as shown in FIGS. 5 and 6, it has the following drawbacks.

In FIGS. 5 and 6, 9 is a release agent application roller, 14
is a holder that holds the release agent application roller 9. The holder 14 can be attached to the guide 17 with one touch while keeping the release agent application roller 9 rotatable. The guide 17 has arm portions 17B at both ends, and a shaft 17.
It can be rotated freely around A. A compression spring 10 is inserted between the guide 17 and the holder 14, and constantly applies a downward force to the holder 14. A tension spring is attached to the opposite side of the guide across the shaft 17A, and applies a moment in the direction of arrow P about the shaft 17A to the guide.

When the above-mentioned release agent application roller 9 is not in contact with the fixing roller, the solenoid is in the state of leaf F, so arrow A
The fixing roller 1 and the release agent application roller 9 are biased by the moment in the direction, and are in the particular positional relationship shown in FIG.

When the solenoid is turned on from this state, the iron core of the solenoid is attracted and pushes the lever 18 or the upper surface of the guide 17 downward. Then, the kite 17 rotates counterclockwise about the shaft 17A, and the release agent application roller 9 comes into contact with the fixing roller 1. Even after contact, the guide is pushed by the lever 18 and the spring 10 is deformed. The contact between the fixing roller and the release agent coating roller is completed when a certain amount of pressure is applied due to the deformation of the spring.

However, in the above conventional example, ■ the guide 17 or the lever 18
Since the guide 17 is pressed by the fuser roller or the end point in the axial direction parallel to the axis of the fixing roller, the pressure balance at both ends is not equal due to deformation such as twisting around the axis of the guide 17. The release agent discharging part may not be uniform on the left and right sides at both ends, and the dimensional error of the spring or the guide attached to the spring or the pressure fluctuation of the release agent application member may be affected, etc. It is not easy to create a structure that applies pressure evenly to the holder. Therefore, if the release agent is not stably supplied and the pressure is too strong, the release agent may be discharged in a large amount and the roller may not be able to function as a release agent application roller until the number of sheets reaches a predetermined number. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that solves the problems of the conventional device described above and makes the release agent discharge amount distribution uniform in the axial (longitudinal) direction of the fixing roller.

Means for Solving the Problem] According to the present invention, the above object is as follows: A fixing roller for fixing an unfixed toner image on a recording material, and a pressure roller that is paired with the fixing roller and rotates following pressure contact. and a release agent application member that contacts the fixing roller to apply a release agent to the fixing roller, and the release agent application member can freely come into contact with and separate from the fixing roller. In the apparatus, this is achieved by the release agent application member coming into contact with the fixing roller due to its own weight.

[Function] In the present invention described below, the release agent coating member contacts the fixing roller due to its own weight. Since there is no problem of deformation, the precision of contact in the longitudinal direction only depends on the manufacturing precision of the release agent application member in the longitudinal direction, and is fairly uniform.

[Example] Hereinafter, the present invention will be described in detail based on FIGS. 1 and 2 of the accompanying drawings.

FIG. 1 is a schematic diagram of an apparatus according to an embodiment of the present invention. In this embodiment, parts common to the conventional apparatus shown in FIGS. 5 and 6 are given the same reference numerals.

In FIG. 1, 1 is a fixing roller formed as a heating roller having a heater 4 therein as a heating source, and 2 is a pressure roller which is in pressure contact with the fixing roller and rotates as a result of the fixing roller. The fixing roller 1 and the pressure roller 2 form a tab at the pressure contact portion, and the recording paper carrying the unfixed toner image, which is carried into the pressure contact portion, is heated and pressurized to perform fixing. .

The surface of the fixing roller l is made of fluororesin (PTFE in this example).
(Polydorafluoroethylene)) 5 is formed, and the pressure roller 2 has a fluororesin film layer 7 formed on the surface of silicone rubber N6 as an elastic layer to improve mold releasability.

Above the fixing roller 1, there is a release agent application roller 3 that supplies and applies a release agent to the fixing roller 1.
It is provided so that it can be freely approached and separated from the The release agent application roller 3 has a felt layer 9 impregnated with a release agent on the surface of a silicone rubber layer 8 having a uniform elasticity. A solenoid 11 is connected to the release agent application roller 3 and receives an operation command from a DC controller 12, and the contact and separation operations are performed by the operation of the solenoid 11.

The release agent application roller 9 is rotatably held by a holder 14 at shaft portions 9^ that protrude from both ends in the longitudinal direction. The holder 14, like the conventional one shown in FIG. 9A
It has a bearing part 16 that supports.

The halter 14 has a guide 1 having arm portions 17B at both ends.
The fixing roller 1 is detachably attached to the fixing roller 1, and can be moved toward and away from the fixing roller 1 by rotating the arm section 17B about the pin 17A.

The holder 14 can also be seen in FIG.

The support center of the bearing portion 16 or the line A connecting the center of the shaft portion 9A of the release agent and the center of the pin 17A is perpendicular to the line B connecting the center of the shaft portion 9A and the center of the fixing roller l. The elongated hole 1 is located as shown in FIG.
6A is formed so that its long sleeves almost coincide with line B of the latter.

Furthermore, a compression spring 2 is installed between the holter 14 and the guide 17 that holds it in order to stabilize the installation state.
A is provided. The spring 20 is a leaf spring bent in the shape of a "<" in order to facilitate attachment and detachment of the holder 14.

Next, the operation in this embodiment will be explained.

4) When the main body of the copying apparatus is stopped or in a standby state where copying signals can be accepted, the release agent applying roller 3 is in a non-contact state with the fixing roller 1 as shown in FIG.

Shun) A photosensitive drum (not shown) and a fixing roller rotate simultaneously with a copy command signal from a user.

(2) After the end of the previous rotation γ, the optical system or document table (both not shown) moves forward and exposes the image signal onto the photoreceptor drum. Thereafter, it is developed and the visible image is transferred to a transfer material.

■ The transfer material carrying the unfixed visible image enters the fixing section by the conveyance system. The release agent application roller 9 comes into contact with the fixing roller l after at least the fixing roller l 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. The release agent applying roller comes into contact with the fixing roller at a timing such that oil is supplied for at least one rotation of the fixing roller l before the recording material enters the nip formed by the fixing roller 1 and the pressure roller.

(2) After oil has been supplied to the fixing roller for at least one rotation, the release agent applying roller 9 is separated from the fixing roller l. This separating operation may be performed while the recording material is being conveyed at the nip portion.

Fixing is carried out as described above. Next, the operation of bringing the release agent application roller into contact with and away from the fixing roller will be explained.

When the fixing roller is brought into contact with and separated from (L), the solenoid 11 is turned on by receiving a signal from the DC controller 12. In conjunction with this, the iron core of solenoid +1 is attracted, the lever 18 rotates, and the end of the guide 17 is pushed. Then, the guide 17 begins to rotate counterclockwise. Accordingly, the holder 14 fixed to the guide and the release agent application roller 9 movably supported by the holder 14 rotate together, and the release agent application roller 9 comes into contact with the fixing roller l. . At this time, as shown in FIG. 2, the long axis direction of the long holes forming the bearing parts 16 at both ends of the holder I4 is
The fixing roller 1 is formed to substantially coincide with a straight line connecting the center of the fixing roller 1 and the center of the shaft portion of the release agent application roller 9. Further, the long axis direction is perpendicular to a line segment connecting the center of the long hole and the rotation center (pin 17A) of the guide 17. therefore,
When the guide 17 is rotated by the arm portion 17B, the release agent application member 9 whose shaft portion was initially at the bottom of the elongated hole due to its own weight is moved between the release agent application roller 9 and the holster 14 as the fixing roller 1 starts to come into contact with the release agent application member 9. The relative position changes, and the center of the release agent application roller 9 moves along the axis of the round elongated hole of the holder 14 and is located near the center. At that time, the bearing part 16
Since the elongated hole 16A coincides with the moving direction of the shaft portion of the release agent application roller 9, the shaft portion operates smoothly with almost no friction between the elongated hole and the side portions of the elongated hole. In this way, the contact between the release agent application roller 9 and the fixing roller I is completed in a uniform state in the axial direction (the state indicated by the two-dot chain line in FIG. 1).

In this state, the release agent applying roller 9 rotates following the fixing roller l, and applies the release agent to the fixing roller 1 for a predetermined period of time.

Next, when the solenoid is turned off after application for a predetermined period of time, the guide 17 begins to rotate clockwise due to the biasing force of the tension spring 19. Along with this, Guide 17
The holder 14 fixed to the fixing roller 1 moves, and the release agent applying roller 9 separates from the fixing roller 1 and returns to the initial standby position.

In the present invention, in order to obtain an appropriate contact pressure of the release agent application roller, it is necessary to change the outer diameter of the metal supporting member of the release agent application roller, so-called core metal, or to make it into a hollow vibrator shape. This can be easily achieved through treatment.

[Effects of the Invention] As explained above, in the present invention, in the contact/non-contact operation of the release agent application roller, the five contacts at the time of contact are performed only by the weight of the release agent application roller, so it is very simple. While maintaining a uniform balance of contact pressure in the axial direction,
This has the effect of enabling contact and non-contact movements.

[Brief explanation of drawings]

FIG. 1 shows a device according to an embodiment of the present invention. Essential configuration diagram, 2nd
The figure shows the relative dynamic relationship of the release agent coating device of the device shown in FIG. 1 with respect to the fixing device. B) shows another conventional device I! E Required configuration diagram, Figure 5 is Figure 4 (A), (B)
FIG. 6 is a front view of the device shown in FIG. 5. FIG. 6 is a front view of the device shown in FIG. 1... Fixing roller 2... Pressure roller 9... Release agent application member (release agent application roller) 9
A...Shaft part 16...Bearing part

Claims (3)

[Claims] (1) A fixing roller for fixing an unfixed toner image on a recording material, a pressure roller that is paired with the fixing roller and rotates under pressure, and a release agent that comes into contact with the fixing roller and is applied to the fixing roller. In a fixing device that has a release agent application member that applies a release agent, and the release agent application member can freely contact and separate from the fixing roller, the release agent application member contacts the fixing roller due to its own weight. A fixing device characterized by: (2) The fixing device according to claim 1, wherein the release agent applying member is a roller having a felt layer around a core metal, and is driven to rotate when it comes into contact with the fixing roller. (3) The release agent application member is formed as a release agent application roller having a shaft portion at both ends, and the shaft portion is supported by a bearing portion of a relatively rotatable guide, and the shaft support portion of the bearing portion is formed to extend almost in line with a line connecting the center of the release agent application roller and the center of the fixing roller, and this line is a line connecting the center of the release agent application roller and the center of rotation of the guide. The fixing device according to claim 1, wherein the fixing device is substantially orthogonal to the fixing device.