JPH04372973A - Heating device - Google Patents

Abstract

PURPOSE:To simplify the drift control structure of a film in a film heating type heating device. CONSTITUTION:In a heating device having a fixed heating element 14, heat- resistant film 8 pressed with the inner face to the heating element 14 and moved and driven, and a pressing roller 9 forming a nip section N by pinching the film 8 between it and the heating element 14 and pressing a heated material P conveyed between the nip section N and the outer face of the film 8 to the heating element 14 via the film 8; the pressing roller 9 is pressed to the heating element 14 across the film 8 and rotated and driven by a driving source to move the film 8 in the conveyance direction of the heated material P at the preset speed, and it practically has a taper shape.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention involves introducing a material to be heated, such as a recording material that supports a microscopic image, onto the side opposite to the heating body side of a heat-resistant film that is brought into pressure contact with a heating body and driven to move. The present invention relates to a film heating type heating device that applies heat from the heating body to the heated material through the film by passing the heating body together with the film in close contact with the film.

[0002] This device is used in electrophotographic copying machines, printers,
A recording material (transfer material sheet, It can be used as an image heating fixing device that fixes toner images formed on electrofax sheets, electrostatic recording sheets, printing paper, etc.) as permanently fixed images.

Further, it can be used, for example, in a device that heats a recording material carrying an image to modify its surface properties (polishing, etc.), a device that performs temporary adhesion treatment, and the like.

0004

[Prior Art] Conventionally, for example, Japanese Patent Application Laid-Open No. 63-313182
As in the publication, there is a fixedly supported heating body (hereinafter referred to as a heater), a heat-resistant fixing film that is conveyed (moving and driven) while being in pressure contact with the heater, and a recording material is transferred to the heater through this film. It has a pressure member that brings it into close contact with the
2. Description of the Related Art An apparatus has been proposed in which an unfixed image formed and carried on the surface of the recording material is heated and fixed onto the surface of the recording material by applying heat from a heater to the recording material through a fixing film.

FIG. 6 schematically shows the main parts of an example of an image heating fixing device of this main type using an endless belt film as a heat-resistant fixing film.

[0006] Reference numeral 8 denotes a thin heat-resistant fixing film in the form of an endless belt or a long web with ends that is wound on a roll and fed out. The heater 14 is in pressure contact with a pressure roller 9 serving as a pressure member through the fixing film 8 with a predetermined contact pressure, thereby forming a fixing nip N.

[0007] A recording material P as a heated material carrying an unfixed toner image Ta is conveyed from the image forming unit side (C) (not shown) and is brought into close contact with the film 8 and passes through the fixing nip N together with the film. Then, in the process of passing through the fixing nip portion N, it is heated and pressurized. During this process, the toner image is softened, melted, and solidified to form a permanently fixed image Tb.

[0008]

[Problems to be Solved by the Invention] However, such a film heating type device has the following problems. In other words, the film 8 is pressed against the heater 14 with a predetermined contact pressure.
If the pressure roller 9 that presses the heater 1 is of a general straight shape, the heater 1 may
At the nip N with the film 8, the pressure distribution applied to the film 8 by the pressure roller 9 in the film width direction becomes non-uniform. Therefore, the conveying force of the pressure roller 9 against the traveling film 8 becomes non-uniform in the film width direction, causing the fixing film 8 to shift in an undefined direction, making the configuration for controlling this movement complicated.

Furthermore, as shown in FIG. 7, the relationship of the frictional forces among the members 14, 8, 9, and P is as follows: a. Friction coefficient μ1 between the heater 14 and the inner surface of the film 8, b. The coefficient of friction between the outer peripheral surface of the film 8 and the recording material P is μ2, c. If the coefficient of friction between the outer peripheral surface of the film 8 and the pressure roller 9 is μ3, then μ1<
It can be expressed as μ2<μ3, but when the recording material P is conveyed at least within the nip portion N such that the widthwise end of the recording material P overlaps the widthwise end of the film 8 (hereinafter referred to as one-sided reference conveyance). While the recording material P passes through the nip portion N, the film 8 is subjected to different conveying forces in the width direction. In other words, from the above-mentioned friction coefficient relationship (μ2<μ3), the conveying force of the film 8 is greater in the non-sheet passing portion of the film 8 than in the sheet passing portion, and therefore the film 8 is moved toward the non-sheet passing side where the conveying force is greater. Move closer. In the conventional example described above, it is impossible to limit the direction in which the film 8 shifts, so if the film 8 shifts to the non-sheet passing side before the recording material P is conveyed, the shift direction of the recording material P The shifting force of the film 8 further increases due to conveyance, and sometimes it becomes impossible to control the shifting.

The object of the present invention is to simplify the control of the deviation of the film 8.

[0011]

[Means for Solving the Problems] The present invention includes a fixed heating body, a heat-resistant film whose inner surface is pressed against the heating body and is driven to move, and the film is sandwiched between the heating body. In a heating device comprising a pressure roller that forms a nip portion and presses the material to be heated conveyed between the nip portion and the outer surface of the film through the film to the heating body, the pressure roller The roller is in pressure contact with the heating body with the film sandwiched therebetween and is rotationally driven by a drive source to drive the film to move at a predetermined speed in the direction of conveyance of the heated material, and is characterized by having a substantially tapered shape. This is a heating device.

0012

[Operation] That is, according to the present invention, the inner surface of the film is brought into pressure contact with a heating element (heater), and the pressure roller that drives the film is tapered in the width direction of the film, so that the film is moved and driven. The direction in which the film shifts can be limited to one direction on the large diameter side of the pressure roller, making it possible to simplify the shift control.

[0013]

Embodiment Embodiment 1 (FIGS. 1 to 3) (1) Example of image forming apparatus FIG. 3 is a schematic diagram of the configuration of an example of a laser beam printer using a heating device according to the present invention as a fixing device.

Reference numeral 1 denotes an electrophotographic photosensitive drum (hereinafter abbreviated as drum) which is rotated clockwise as indicated by an arrow at a predetermined circumferential speed (process speed). During the rotation process, the drum 1 is uniformly charged to a predetermined positive or negative potential by a primary charger 2, and then scanned and written with target image information by laser scanning exposure L by a laser scanner 3. As a result, an electrostatic latent image corresponding to the target image information is formed on the drum 1.

The surface of the drum on which the latent image has been formed is supplied with toner T by the developing device 4 and is developed as a toner image.

Next, in the process of passing the transfer roller 5, the toner image moves between the transfer roller 5 and the drum 1.
In between, the recording material (transfer paper) fed from a paper feeding section consisting of a paper feed cassette 20, a paper feed roller 21, a separation claw or separation pad 22, a pair of registration rollers 23, etc. is sequentially transferred onto the surface P of the recording material (transfer paper). . The transfer from the drum 1 to the surface of the recording material P is performed by charging the back side of the recording material P surface with a polarity opposite to that of the charging polarity on the transfer roller 5.

The recording material P to which the toner image has been transferred is neutralized by a static eliminating needle 6 to which a voltage of opposite polarity to that of the transfer roller 5 is applied, separated from the drum 1, and conveyed to a fixing device 7 where the toner image is fixed. The paper is received and discharged to the outside of the machine by the paper discharge roller 24.

After the recording material has been separated, the surface of the drum is cleaned by a cleaning device 25 to remove residual deposits such as untransferred toner and is repeatedly used for image formation. (2) Fixing Device 7 In the fixing device 7, the unfixed toner image on the surface of the recording material P is heated and melted, and is fixed on the surface of the recording material P as a permanently fixed image.

FIG. 3 shows a cross section of the fuser 7. 1 and 2 are a longitudinal sectional view of the fixing device 7 and a front view of the pressure roller 9. FIG.

The fixing film 8 has heat resistance, toner releasability,
It is a tough single-layer fixing film or a composite layer film that has been subjected to desired surface treatment or lamination treatment. For example, heat-resistant polyester (PET) of approximately 50 μm
or polyimide (P1) single layer film, or a composite layer film in which the surface of the film is further treated to provide a release layer with tetrafluoroethylene (PTFE).

In the fixing device 7 of this embodiment, the fixing film 8 has an endless cylindrical shape, and there is no tension in the circumferential direction except for the nip portion N, and it rotates only by the frictional force with the pressure roller 9. It is configured to run.

The pressure roller 9 has a tapered shape, and the pressure roller 9 and the heater 14 are in contact with a film guide member 10 that guides the inner surface of the fixing film 8 over the entire longitudinal direction, and the pressure roller 9 presses the fixing film 8 between them. Pressure spring 1
1a and 11b are brought into pressure contact with each other with a predetermined contact pressure (for example, a total pressure of 3 to 6 kg for A4 width).

[0023] On the surface of the heater 14, TaSi is formed by vapor deposition, sputtering, CVD, screen printing, etc.
There are linear or strip-shaped thin film heating resistors made of O2, silver palladium, Ta2N, RuO2, nichrome, etc.

[0024] Tapered pressure roller 9
The fixing film guide member 1 is disposed on the larger diameter side D2 of the fixing film guide member 1.
There is a flange 13 attached at the time of assembly, and the shift of the fixing film 8 that occurs when the fixing device 7 is driven is controlled by regulating the edge of the fixing film 8.

After the recording material P to which the unfixed toner image has been transferred is conveyed to the fixing nip portion N together with the fixing film 8 by the surface friction force of the pressure roller 9 rotated by the drive gear 12, the recording material P is transported to the fixing nip portion N at least. Now, the pressure spring 11
The recording material P is sent in the traveling direction of the recording material P at the same speed as the fixing film 8 and the pressure roller 9 without slipping due to the contact pressure from a and 11b.

The process of passing through the fixing nip N is a heating and pressurizing process, and the heat of the heater 14 is transmitted to the recording material P via the fixing film 8, and the unfixed toner on the recording material P is melted and softened. Pressurized.

After passing through the fixing nip N, the fixing film 8 and the recording material P are conveyed while remaining in close contact with each other due to the adhesive force of the melted and softened toner. This conveyance process is used as a cooling process, and the heat of the melted and softened toner is radiated, the toner is cooled and solidified, and a permanently fixed image is formed on the recording material P.

After the cooling process, the fixing film 8 and the recording material P are easily separated by the toner cooling and solidification, and the recording material P is discharged from the fixing device 7.

Since the pressure roller 9 that rotates and runs the fixing film 8 while pressing the inner surface of the fixing film 8 against the surface of the heater 14 has a tapered shape, the width of the fixing nip formed has a tapered shape. A uniform gradient results. That is, there is a difference in the force that causes the fixing film 8 to run, and a difference occurs in the force that causes the fixing film 8 to run, and the fixing film 8 is moved in the direction A of the side D2 where the pressure roller 9 has a larger diameter.
(Fig. 1) receives a moving force. Furthermore, for example, even if the recording material P is conveyed on a one-sided basis, the resulting shift of the fixing film 8 in the non-sheet-passing side direction B causes the recording material P to be conveyed on the side D2 of the pressure roller 9 with a larger diameter. If conveyed as a reference, due to the tapered shape of the pressure roller 9, A≧
B. That is, regardless of the conveyance standard of the recording material P, the deviation of the fixing film 8 can be limited to one direction.

Therefore, this embodiment has the following effects.

[0031]■. Conventionally, when the direction in which the fixing film 8 shifts cannot be limited, shift regulating members (for example, flanges 13, etc.) are required at both ends of the fixing film 8 in the width direction.
However, the fixing film 8 shifts only on one side in the direction A, which simplifies the shift control of the film 3, reduces the number of parts, and reduces costs.

[0032]■. Since the direction in which the fixing film 8 moves can be limited by the shape of the pressure roller 9, the edges of the fixing film 8, which rotates and travels with its edges regulated, need only be reinforced on one side in the direction of shifting, which reduces the cost of the fixing film itself. It can be reduced.

<Embodiment 2> (FIG. 4) FIG. 4 is a perspective view of the main parts of a fixing device 7 as a second embodiment. Inside the endless fixing film 8, there are a guide member 10 as a travel guide for the fixing film and a heater 14. The fixing film 8 is sandwiched between a tapered pressure roller 9 and a heater 14 , and is rotated by the surface friction force of the pressure roller 9 driven by a drive gear 12 . The shifting direction of the fixing film 8 that occurs during rotation is the A direction of the larger diameter side D2 of the pressure roller 9, and the control is such that the outer circumferential surface of the fixing film 8 on the side opposite to the shifting direction A has a uniform width. ,
This is done by regulating ribs 15 made of heat-resistant resin fixed at a certain height with rib regulating plates 16.

The materials and structure of the fixing film 8 and the guide 10, and the tapered shape of the pressure roller 9, are exactly the same as in Example 1.

Therefore, in the second embodiment, as in the first embodiment, when the recording material P is conveyed, only the tapered shape of the pressure roller 9 is used to control the shifting direction of the fixing film 8, regardless of the conveyance standard.
Since the shifting force can be limited, the rib regulating plate 16 is provided only on the side in the shifting direction of the fixing film 8 with respect to the ribs 15, thereby enabling simplified shifting control.

<Embodiment 3> (FIG. 5) FIG. 5 is a perspective view of the main parts of a fixing device 7 as a third embodiment. Inside the fixing film 8, there are a film transport roller 17, a tension roller 18, and a heater 14, and the fixing film 8 is suspended and stretched between these members 17, 18, and 14.

The pressure roller 9 as a pressure member has a tapered shape, and is rotated by a drive gear 12 while contacting the heater 14 and the fixing film 8 via the fixing film 8. 8 is rotated. The shifting direction A of the rotating fixing film 8 is as follows:
As in Embodiments 1 and 2, the conveyance of the recording material P can be controlled by the tapered shape of the pressure roller 9 regardless of the conveyance standard. This is possible by simply moving up and down at a fixed timing, making it possible to perform simple shift control. S is a solenoid device or the like that moves the shaft of the tension roller 18 up and down.

[0038] The film 8 is not limited to the endless belt shape of the embodiment, but may also be a long film with an end wound into a roll, which is fed out and run.

[0039]

As described above, the film heating type heating device of the present invention has a tapered pressure roller that runs the film while pressing the inner surface of the heat-resistant film against the heating element, thereby reducing the film conveyance force. By making a difference and limiting the direction in which the film shifts, the structure of shift control, which was conventionally complicated, can be simplified, and shift can be managed only by the tapered shape. The uncontrollable deviation that occurred when the recording material was conveyed on one side has been resolved.

[Brief explanation of drawings]

[Figure 1] Longitudinal front view of the fixing device of the first embodiment

[Figure 2]
Front view of pressure roller

[Figure 3] Schematic configuration diagram of an example of a laser beam printer using the fixing device

[Fig. 4] Perspective view of main parts of second embodiment fixing device

[Figure 5]
Perspective view of main parts of third embodiment fixing device

[Figure 6] Schematic diagram of a film heating type heating device

[Figure 7] Friction coefficient relationship diagram between main parts

[Explanation of symbols]

1: Electrophotographic photoreceptor 2: Primary charger 3: Laser scanner 4: Developing device 5: Transfer roller 6: Static elimination needle 7:Fuser 8: Fixing film 9: Pressure roller 10: Guide 11: Pressure spring 12: Drive gear 13: Flange 14: Heater 15: Rib 16: Regulation plate 17: Conveyance roller 18: Tension roller

Claims (1)

[Claims] 1. A nip is formed by sandwiching the film between a fixed heating body, a heat-resistant film whose inner surface is pressed against the heating body and is driven to move, and the heating body. In the heating device, the pressure roller presses the material to be heated, which is conveyed between the outer surface of the film and the heating body through the film, into contact with the heating body, the pressure roller presses the material between the film and the heating body through the film. 1. A heating device characterized in that the roller is a roller that is rotationally driven by a drive source while being in pressure contact with each other to move the film at a predetermined speed in a direction in which the material to be heated is conveyed, and that the roller has a substantially tapered shape.