JP2000321893A - Heat fixing device and image forming device - Google Patents

Abstract

(57) [Problem] In a film fixing device driven by a pressure roller, it is necessary to strictly control the outer diameter shape standard of the fixing film in order to prevent paper wrinkles, and the yield is reduced and the cost is reduced. There was a problem of going up. SOLUTION: On a support member 12 rotatably supporting a heat-resistant fixing film 11, a rotatable sliding member 22 (23, 24) which rotates following the fixing film is provided on a surface facing the fixing film.
a, 24b, 25).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a heating member comprising a heater, a heat-resistant fixing film which slides on the surface of the heater, and a supporting member which rotatably supports the fixing film, and a fixing member comprising: A recording material for holding an unfixed image formed by an electrophotographic method or an electrostatic recording method, comprising a pressurizing rotating member that presses a heater to form a heating nip portion and rotates the fixing film in a driven manner. The present invention relates to a heat-fixing device that conveys a sheet through a heating nip portion and heats and presses a recording material at the heating nip portion to fix an unfixed image on the recording material as a permanent image, and an image forming apparatus to which the heat-fixing device is applied. It is.

[0002]

2. Description of the Related Art Conventionally, a printer using an electrophotographic system,
As a method of fixing an unfixed image formed on a recording material by a copying machine, a facsimile, or the like, a contact heating type fixing device having good thermal efficiency and safety is widely known. Especially in recent years, from the viewpoint of energy saving promotion, heat transfer efficiency is high,
An energy-saving type film heating type fixing device, which starts up quickly, is often used.

A fixing device of this film heating type is disclosed in, for example, JP-A-63-313182 and JP-A-2-157.
878, JP-A-4-44075 to JP-A-4-44075
44083, JP-A-4-204498
No. 0 to Japanese Patent Application Laid-Open No. 4-2044984, etc., in which a heat-resistant film (fixing film) is brought into close contact with a heater by a pressing rotating member (pressing roller) and is slid and conveyed. A recording material carrying an unfixed image is introduced into a press-contact nip formed by a heater and a pressure roller with the film interposed therebetween, conveyed together with the fixing film, and a heater applied via the fixing film. The unfixed image is fixed as a permanent image on the recording material by the heat from the nip and the pressing force of the pressing nip portion.

The fixing device of the film heating system includes a system in which a fixing film is conveyed between a pressure roller and a tension roller by using a dedicated film conveying roller and a driven roller for conveying the fixing film. There is known a method in which a fixing film is loosely fitted to a supporting member (film guide) and a pressing roller is driven to rotate the fixing film with respect to the pressing roller (pressing roller driving method). However, in recent years, the latter pressure roller driving method, which has a small number of components, can be easily miniaturized, and can be realized at low cost, is often adopted.

[0005]

However, in the film fixing device of the pressure roller drive type, the fixing film is fitted to the supporting member without tension.
In the case of using a film having a so-called middle bulge shape in which the outer diameter at the center of the fixing film is larger than the outer diameter at the end, the recording material is conveyed according to the shape. In this case, in the fixing film, the peripheral speed of the film on the left and right end portions having a small outer diameter is smaller than the peripheral speed of the film on the central portion having a large outer diameter. Therefore, the recording material P is located between the fixing film and the end of the recording material.
(Force in the direction of arrow a in FIG. 8) acts.
At this time, as shown by an arrow b in FIG. 8, a force is applied to the recording material P to move the left and right ends of the recording material toward the center, and paper wrinkles C are generated at the rear end of the recording material.

On the other hand, by fixing the fixing film by the support member 101 and correcting the longitudinal shape of the fixing film immediately before entering the heating nip portion, when the recording material passes through the heating nip portion, the fixing film moves from the fixing film to the recording material. It is conceivable to eliminate such a force and prevent paper wrinkles,
In this case, the frictional resistance between the support member and the fixing film increases, the torque increases, the rotation of the fixing film stops,
The paper will slip. In particular, as the fixing speed increases, it becomes more difficult to balance both the prevention of paper wrinkling and the prevention of slippage.

[0007] Therefore, in the film fixing device of the pressure roller drive type, it is necessary to strictly control the outer diameter shape standard of the fixing film in order to prevent paper wrinkles, and there is a problem that the yield decreases and the cost increases. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In a film fixing apparatus of a pressure roller drive type, the frictional resistance between the fixing film and a supporting member is reduced to reduce the fixing film. It is an object of the present invention to provide a heat fixing device capable of preventing a rotation failure and a recording material slip caused by the rotation, preventing a paper wrinkle, and preventing a fixing film from being twisted or damaged for a long time.

It is another object of the present invention to provide an image forming apparatus which can apply a heat fixing device to smoothly convey a recording material and form a high quality image.

[0010]

According to the present invention, there is provided a heat fixing apparatus and an image forming apparatus having the following constitution.

(1) A heating member composed of a heater, a heat-resistant fixing film that slides on the heater surface, and a support member that rotatably supports the fixing film, and the fixing film is pressed against the heater. A pressurizing rotating member for forming a heating nip and rotating the fixing film in a driven manner, wherein the recording material holding the unfixed image is conveyed through the heating nip to heat the recording material at the heating nip. In a heat fixing device that pressurizes and fixes an unfixed image on the recording material as a permanent image, a rotating sliding member that is driven to rotate with the fixing film is provided on a surface of the support member that faces the fixing film. Heat fixing device.

(2) The heat fixing device according to (1), wherein the rotary sliding member is disposed at a longitudinal end of the support member.

(3) The rotary sliding member is a cylindrical roller having an outer diameter difference in a longitudinal direction, and is arranged such that the outer diameter increases as it goes outward with respect to the recording material width direction. The heat fixing device according to (1), which is characterized in that:

(4) The rotary sliding member is a cylindrical roller, and the rotation axis of the smooth roller has an angle with respect to the virtual center axis of the fixing film with respect to the recording material passing direction. (1) The heat fixing device according to (1), wherein

(5) Image forming means having image forming means for forming and carrying an unfixed image on a recording material, and heat fixing means for heating and fixing the unfixed image formed and carried on the recording material to the recording material. An image forming apparatus, wherein the heat fixing unit is the heat fixing device according to any one of (1) to (4).

[0016]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a configuration diagram of a heat fixing device 6 according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 10 denotes a pressing roller as a pressing member;
6, an elastic layer 17 formed by foaming heat-resistant rubber such as silicon rubber or fluorine rubber or silicon rubber is provided. Also, PFA, PTF is formed on the elastic layer 17.
A release layer 18 such as E or FEP may be formed.

Reference numeral 9 denotes a heating member, which comprises a heater H, a heat-resistant fixing film 11 sliding on the heater surface, and a heat-insulating supporting member (film guide member) 12 rotatably supporting the fixing film. It is configured. The fixing film 11 is made of polyimide, polyamideimide, PEEK, PES, PPS, heat-resistant, thermoplastic having small heat capacity.
It is a cylindrical film such as PFA, PTFE, and FEP.
Then, in order to prevent offset and ensure the separating property of the recording material, a heat-resistant resin having good releasability such as PFA, PTFE, FEP or the like is mixed or coated alone on the surface layer.

The heater H includes a thermistor 13, a heater substrate 14, and a heating element 15, and includes a fixing film 11;
And heats the heating nip N for melting and fixing the toner image T on the recording material 8.

A heat-insulating support member 12 for holding the heater H and preventing heat radiation in the direction opposite to the heating nip portion N is made of a liquid crystal polymer, phenol resin, PPS, PEEK, or the like. Is a guide G composed of an end support member 20 and a center support member 21 having a shape and a size that can be turned with a margin in the direction of the arrow.

Further, since the fixing film 11 rotates while sliding on the heater H and the support member 12, it is necessary to reduce the frictional resistance between the heater H and the support member 12 and the fixing film 11. Therefore, a small amount of lubricant such as heat-resistant grease is interposed between the surfaces of the heater H and the support member 12. Thus, the fixing film 11 can rotate smoothly.

The recording material 8 having an unfixed image formed by the toner T on the surface thereof is applied to the pressure roller 10 and the fixing film 1.
As the toner T passes through the heating nip portion N, the toner T is heated and pressurized and melted, and is fixed on the recording material 8. The conveying force at this time is limited to only the pressure roller in the case of the fixing film fixing device driven by the pressure roller 10,
The fixing film itself takes a following shape and rotates with the recording material 8.

In this case, the heat-resistant grease and the supporting member 12 play important roles. The heat-resistant grease is used for lubricity between the fixing film 11 and the support member 12, and the support member 12 has an application in which the heat of the fixing film itself is not released.

In the present invention, as shown in FIGS.
A driven roller 22 made of a resin such as POM and formed into a cylindrical shape is provided at both ends of the support member 12 on the opposite side of the fixing film, and the driven roller 22 applies tension to the fixing film 11 near the heating nip portion N. Since the paper wrinkles are prevented by keeping the longitudinal shape of the fixing film 11 just before the heating nip portion N straight, the driven roller 22 is located near the heating nip portion on the upstream side (the recording material entry side) of the support member 12. It is desirable. Thus, the fixing film 11
Is guided by the driven rollers 22, so that the support member 1 is
The rubbing resistance between the fixing film 2 and the fixing film 11 can be eliminated.

Table 1 shows that the driven roller 22 from the support member 12
Shows the relationship between the protrusion amount x of paper and paper wrinkles and slips. As a comparative example, an example is shown in which the fixing member is taken out of the support member 12 and tension is applied to the fixing film 11.

A film-heating type fixing method in which a polyimide-based fixing film 11 having an outer diameter of Φ25 and a solid silicone rubber roller having a diameter of Φ25 are used as the pressure roller 10 and the pressure roller 10 is pressed against a heater with a total pressure of 9 kgf. As shown in FIG. 3A, a POM roller 22 having a width of 20 mm is provided in the apparatus in a longitudinal direction of 5 to 25 mm from the end of the recording material passage area, and in FIG. As described above, it is placed 3 mm before the heating nip entrance,
Table 1 shows the relationship between the paper wrinkle and the slip when the amount of protrusion X of the driven roller 22 from the support member 12 is changed.

In the first embodiment, the fixing film 11 having an outer diameter difference of 40 μm at the center with respect to the outer diameter at the end is used, and the recording material 8 is a normal temperature and normal humidity environment (20 ° C., 60% R).
H) Using A4 size plain paper left for 3 days,
The table shows the number of paper wrinkles or slips generated when printing 100 sheets.

[0028]

[Table 1]

As shown in Table 1, as the amount of protrusion x of the driven roller 22 from the support member 12 increases, the effect of stretching the fixing film 11 increases, and the frequency of occurrence of paper wrinkles decreases. This is because when the fixing film 11 is stretched by the driven roller 22, the difference in outer diameter of the fixing film is reduced, and FIG.
This is because the fixing film 11 rotates at a substantially uniform outer peripheral speed in the longitudinal direction of the film as shown in FIG.

At this time, the fixing film 11 is
In this case, no sliding resistance is applied to the fixing film 11, so that no slip occurs. On the other hand, when the fixing film 11 is stretched by the fixing member, the effect on wrinkles can be obtained in the same manner as when the fixing film 11 is tensioned by the driven roller 22, but as the protrusion amount of the fixing member increases, the fixing The sliding resistance between the film 11 and the support member 12 increases, and the rotation of the fixing film 11 is inhibited, so that slip occurs. For this reason, when the fixing film 11 is stretched by the fixing member, it is difficult to set both the paper wrinkle prevention and the slip prevention.

As described above, when the driven roller 22 having good slidability is provided on the surface of the support member 12 facing the fixing film as in the present invention, the sliding resistance between the support member 12 and the fixing film 11 is eliminated. Even if tension is applied to the fixing film 11 by the driven roller 22 to prevent paper wrinkles, it is possible to eliminate a recording material slip due to a poor rotation of the fixing film 11.

Embodiment 2 FIG. In the second embodiment, a driven roller 23 is provided on the surface of the support member 12 opposite to the fixing film, and the driven roller 23 applies tension to the fixing film 11 and, at the same time, changes the shape of the driven roller 23 to the recording material 8.
The outer diameter of the portion facing the outside is large, and the outer diameter on the side near the center is small, thereby giving a force to stretch the fixing film 11 outward.

FIG. 4 is a schematic sectional view of a film heating type fixing device to which the second embodiment is applied. Since the basic configuration of the fixing device is the same as that of the first embodiment, the duplicate description will be omitted. The driven rollers 23 having a tapered shape shown in FIG. 4A are arranged so that the diameter increases toward the left and right ends of the fixing film 11.

In the second embodiment, the outer diameter of the center end of the driven roller 23 is φ4 mm, and the left and right ends are φ5 mm.
A 5 mm taper was provided. The width of the driven roller 23 is 20 mm, which is the same as in the first embodiment. As described above, when the supporting member 12 and the driven roller 23 have a shape in which the outer diameter increases toward the left and right ends of the fixing film 11, the fixing film 11 rotates during rotation as shown in FIG. Is generated on the left and right end sides in the longitudinal direction, and a force Fb for extending the recording material 8 in the heating nip N outward is also applied to the recording material 8, thereby obtaining a higher paper wrinkle prevention effect. .

By adopting such a configuration, even if the tension applied to the fixing film 11 is reduced, a high wrinkle prevention effect can be obtained, so that the margin for slip can be widened. Further, by adopting a configuration in which a force for extending the fixing film is applied to the left and right ends of the fixing film 11 as in the second embodiment, when the fixing device is rotated for a long period of time, the fixing film 11 is positioned at the center. The problem of film breakage caused by gradually moving to the portion can also be prevented, and the life of the fixing film 11 can be extended.

In the prior art, the life for film breakage was about 250,000 pages, but in the heating and fixing apparatus to which the second embodiment is applied, even if the printing is 400,000 pages, fixing is performed. Good results were obtained without warping or tearing of the film 11. Further, as shown in FIG. 5, the driven roller 23 is a set of a plurality of rollers 24a and 24b, and the driven roller 23 may be configured such that the outer diameter of the driven roller becomes larger as it goes outside the recording material passing area. It is possible to obtain exactly the same effect as when the tapered driven roller 23 is used.

Embodiment 3 In the third embodiment, a skew feeding roller 25 is disposed on the surface of the support member 12 opposite to the fixing film, and is inclined obliquely with respect to the recording material passing direction. FIG. 6 is a schematic sectional view of a heat fixing device to which the third embodiment is applied. Note that the basic configuration of the fixing device other than the driven rollers is the same as that of the above-described embodiment, and therefore, the description thereof will not be repeated.

In the driven roller 25 shown in FIG. 6, a POM roller formed into a cylindrical shape is disposed on the surface of the film guide facing the fixing film so as to be oblique to the recording material passing direction. The pressure roller 10 is rotated to drive the fixing film 1
When the roller 1 is driven to rotate, the oblique feed driven roller 25 is driven to rotate in the direction of the arrow R shown in FIG. Due to the rotation of the oblique feeding roller 25, a force is applied to the fixing film 11 in the direction of the arrow Fc in FIG. 6, and as a result, a force for extending the fixing film outward is exerted on the entire fixing film during the rotation driving. The effective range of the tilt angle of the driven roller 25 varies depending on the width of the driven roller. For example, when the driven roller 25 having a width of 20 mm is used, a good result is obtained when the driven roller 25 is set to about 10 to 30 °.

According to the third embodiment, the driven roller 2
5 is inclined, so that the inside blister shape of the fixing film 11 is corrected.
Paper wrinkles can be prevented from occurring, and the fixing film can be prevented from being damaged during long-term use.

Embodiment 4 FIG. FIG. 7 is a configuration diagram of an image forming apparatus according to Embodiment 4 of the present invention. In FIG. 7, reference numeral 1 denotes a photosensitive drum, which is OPC, amorphous S
e, a photosensitive material such as amorphous Si is formed on a cylindrical substrate such as aluminum or nickel. The photosensitive drum 1 is driven to rotate in the direction of the arrow, and its surface is first uniformly charged by a charging roller 2 as a charging device.

Next, scanning exposure is performed by a laser beam 3 which is ON / OFF controlled according to image information, and an electrostatic latent image is formed. This electrostatic latent image is developed by the developing device 4,
Be visualized. As the developing method, a jumping developing method, a two-component developing method, an FEED developing method, and the like are used.
Image exposure and reversal development are often used in combination.

The visualized image of the toner T is transferred from the photosensitive drum 1 onto the recording material 8 conveyed at a predetermined timing by a transfer roller 5 as a transfer device.
At this time, the recording material 8 is nipped and conveyed between the photosensitive drum 1 and the transfer roller 5 with a constant pressing force. The recording material 8 to which the image of the toner T is transferred is conveyed to the fixing device 6 and fixed as a permanent image. On the other hand, the transfer residual toner remaining on the photosensitive drum 1 is removed from the surface of the photosensitive drum 1 by the cleaning device 7.

According to the fourth embodiment, since the heat fixing apparatus of the present invention is applied, the recording material can be smoothly conveyed, and a high-quality image can be formed without fixing trouble.

[0044]

As described above, according to the present invention,
In a pressure roller driving type film fixing device, a driven roller that rotates following the fixing film is provided on a surface of the supporting member opposite to the fixing film, and a sliding resistance between the fixing film and the supporting member is reduced, so that a fixing film is formed. In addition to preventing the rotation failure and the recording material slip caused by the rotation, the driven roller stretches the fixing film and corrects the film shape immediately before entering the fixing unit, thereby preventing paper wrinkles.

The diameter of the driven roller increases as it goes outward in the longitudinal direction of the recording material passing area. Alternatively, by making the driven rollers obliquely fed, a force is applied to extend the fixing film outward when the fixing film is rotationally driven to obtain a higher paper wrinkle prevention effect, and the fixing film distortion generated when the fixing film is used for a long period of time. And a heat fixing device capable of preventing damage.

Further, by applying this heat fixing device, it is possible to obtain an image forming apparatus capable of smoothly conveying a recording material and forming a high quality image.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a heat fixing device according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a supporting state of a fixing film to which the present invention is applied.

FIG. 3 is a diagram illustrating Embodiment 1 of the present invention.

FIG. 4 is a diagram illustrating a second embodiment of the present invention.

FIG. 5 is a diagram illustrating a third embodiment of the present invention.

FIG. 6 is a diagram illustrating a fourth embodiment of the present invention.

FIG. 7 is a schematic sectional view of an image forming apparatus to which the present invention is applied.

FIG. 8 is a diagram illustrating the principle of generation of wrinkles in a film fixing device driven by a pressure roller.

[Explanation of symbols]

Reference Signs List 1 photosensitive drum, 6 heat fixing device, 11 fixing film, 21 film guide (support member), 22, 23,
24a, 24b, 25 Followed rollers.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Junji Naito 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 2H033 AA31 BA11 BE03

Claims (5)

[Claims] 1. A heating member comprising a heater, a heat-resistant fixing film that slides on the heater surface, and a supporting member that rotatably supports the fixing film, and the fixing film is heated by pressing the fixing film against the heater. A pressurizing rotating member for forming a nip portion and rotating the fixing film by rotation, and conveying the recording material holding the unfixed image through the heating nip portion to heat the recording material at the heating nip portion. In a heat fixing device for pressing and fixing an unfixed image on a recording material as a permanent image, a rotating sliding member that is driven to rotate with the fixing film is provided on a surface of the support member facing the fixing film. Heat fixing device. 2. The heat fixing device according to claim 1, wherein the rotary sliding member is disposed at a longitudinal end of the support member. 3. The rotary sliding member is a cylindrical roller having a difference in outer diameter in a longitudinal direction, and is arranged such that the outer diameter increases as it goes outward with respect to the recording material width direction. 2. The heat fixing device according to claim 1, wherein: 4. The rotary sliding member is a cylindrical roller, and the rotation axis of the cylindrical roller is set at an angle to the virtual center axis of the fixing film with respect to the recording material passing direction. The heat fixing device according to claim 1, wherein the heat fixing device is disposed. 5. An image forming apparatus comprising: an image forming unit for forming and carrying an unfixed image on a recording material; and a heat fixing unit for heating and fixing the unfixed image formed and carried on the recording material to the recording material. 5. The image forming apparatus according to claim 1, wherein the heat fixing unit is the heat fixing device according to claim 1. 6.