JPH04204980A - Heater - Google Patents

Abstract

PURPOSE:To eliminate the disturbance of images on a recording material and to reduce the size of the heater of a film heating type by coating the surface of a heating body for sliding with a heat resistant film with a surface protective layer consisting of a specific resin. CONSTITUTION:The surface of the heating body 19 for sliding with the heat resistant film 21 is coated with the surface protective layer 19c consisting of the resin having good heat resistance and slidability, for example, a fluorinated hydrocarbon resin. The fluorinated hydrocarbon resin has the excellent heat resistance and a small coefft. of surface friction and, therefore, the heat resistant film 21 and the recording material are transported and passed in the stably and integrally tight contact state in the position of the heating body without generating a slip between both. The heating treatment of the recording material is thus executed without generating the disturbance of the images. The sliding resistance between the heating body 19 and the heat resistant film decreases and the driving torque of the device is decreased. The size of the device is thus reduced.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention involves bringing a recording material into close contact with a heating body through a heat-resistant film, moving the heating body and the heat-resistant film relative to each other, and dissipating the heat of the heating body. A method of applying the film to the recording material through the adhesive film (
This invention relates to a heating device using a film heating method.

This device is an image heating fixing device in an image forming apparatus such as an electrophotographic copying machine, a printer, or a fax machine, that is, it is made of heat-meltable resin, etc., by an appropriate image forming process means such as electrophotography, electrostatic recording, or magnetic recording. Unfixed toner that corresponds to the desired image information and is formed using toner on the surface of a recording material (transfer material sheet, electrofax sheet, electrostatic recording sheet, printing paper, etc.) using an indirect (transfer) method or a direct method. An image heat fixing device that heats and fixes an image as a permanently fixed image on the surface of a recording material carrying the image; a device that heats the recording material carrying the image to modify its surface properties (such as gloss); It can be used for devices that perform temporary attachment treatment.

(Background Art) Conventionally, for example, a heating device for a recording material for heat fixing an image uses a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and in pressure contact with the heating roller. ,
A heated roller system is often used, which heats the recording material while nipping and conveying it.

In addition, various other methods are known, such as a flash heating method, an oven heating method, a hot plate heating method, a belt heating method, and a high frequency heating method.

On the other hand, the present applicant has proposed a film heating type heating device as described above in, for example, Japanese Unexamined Patent Publication No. 63-313182.

This consists of a fixedly supported heating body, a heat-resistant film (or sheet) that is conveyed (moving and driven) while being in pressure contact with the heating body, and a pressure member that brings the recording material into close contact with the heating body through the film. This device has a system and structure in which an unfixed image formed and carried on the surface of the recording material is heated and fixed on the surface of the recording material by applying heat from a heating body to the recording material through a film.

More specifically, it includes a thin heat-resistant film, a means for moving the film, a heating element fixedly supported on one side of the film with the film inside, and the heating element on the other side. The pressure member is disposed opposite to the heating member and brings the image-bearing surface of the recording material on which the image is to be fixed into close contact with the heating body through the film, and the film is in contact with the film at least when image fixing is performed. It is formed by pressing the heating body and the pressure member with the traveling film in between by moving the film in the forward direction at substantially the same speed as the recording material on which the image is to be fixed and which is conveyed and introduced between the pressure member and the pressure member. By passing through a nip section serving as a fixing section, the developed image-bearing surface of the recording material is heated by the heating body through the film, and thermal energy is applied to the developed image (unfixed toner image) to soften and melt it. This heating means/device is basically a heating device that separates the film and recording material after passing through the fixing section at a separation point.

This kind of film heating type equipment uses a heating element with a fast temperature rise and a thin film, which makes it possible to shorten wait time (quick start) and solve various drawbacks of conventional equipment. Cultivating advantages.

FIG. 10 shows a schematic configuration of an example of this type of image heat fixing device using an endless film as the heat-resistant film.

Reference numeral 51 denotes an endless belt-shaped heat-resistant film (hereinafter referred to as fixing film or simply film), which includes a driving roller 52 on the left side, a driven roller 53 on the right side, and a lower part between these driving rollers 52 and driven rollers 53. The three members 52 and 52 of the low heat capacity linear heating element 19 arranged in parallel to each other are
The suspension is installed between 53 and 19.

The fixing film 51 rotates clockwise at a predetermined circumferential speed as the drive roller 52 rotates clockwise. The recording material sheet P is rotated at approximately the same peripheral speed as the conveyance speed (process speed) of the recording material sheet P.

Reference numeral 55 designates a pressure roller as a pressure member, which holds the downward film portion of the endless heald fixing film 51 between it and the heating body 19, and attaches an unillustrated attachment to the lower surface of the heating body. The recording material sheet P is rotated in a forward counterclockwise direction in the conveying direction of the recording material sheet P.

The heating body 19 is a low heat capacity linear heating body whose length is in the direction intersecting the plane movement direction of the film 51 (width direction of the film), and includes a heater substrate (base material) 19a and a heating element (current-carrying heating resistor) 19b. It is fixedly supported by being attached to a support body 80 via a heat insulating member 20.

A recording material sheet P carrying an unfixed toner image Ta on its upper surface, conveyed from an image forming section (not shown), is guided by a kite 81 and placed between the fixing film 51 and the fixing film 51 at the pressure contact area N between the heating body 19 and the pressure roller 55. The unfixed toner image surface enters between the pressurizing roller 55 and the unfixed toner image surface is brought into close contact with the lower surface of the fixing film 51 which is being rotated in the same direction at the same speed as the conveyance speed of the recording material sheet P, and the unfixed toner image surface is stuck together with the film. The heating member 19 and the pressure roller 55 pass through the mutual pressure contact portion N in an overlapping state.

The heating element 19 is heated with electricity at a predetermined timing, and the thermal energy on the heating element 19 side is transmitted to the recording material sheet P side that is in close contact with the film via the film 51, and the toner image Ta passes through the pressure contact part N. During this process, it is heated and becomes a softened and melted image Tb.

The rotationally driven fixing film 51 changes its traveling direction at a steep angle θ at an edge portion S of the heat insulating member 20 having a large curvature. Therefore, the recording material sheet P, which is conveyed through the pressure contact part N while overlapping with the fixing film 51, separates from the fixing film 51 by the curvature at the edge part S, and is discharged. By the time the toner reaches the paper discharge section, the toner has been sufficiently cooled and solidified and is completely fixed on the recording material sheet P (Tc).

The fixing film 51 is not limited to an endless belt shape.
As shown in the example in FIG. It is also possible to adopt a configuration (film winding type) in which the sheet travels from the side to the winding shaft 83 at the same speed as the conveyance speed of the recording material sheet P.

(Problems to be Solved by the Invention) In this type of film heating type heating device, it is important that the heat-resistant film and the recording material are conveyed and passed through the heating body position while being in close contact with each other. That is, if there is a difference in the transport speed between the heat-resistant film and the recording material and slippage occurs between the two, the image on the recording material that is in contact with the heat-resistant film will be disturbed.

In addition, the sliding resistance between the heating element and the heat-resistant film can be minimized to reduce the device drive torque, or the device drive system can be simplified to reduce the overall size and cost of the device. This is important for achieving energy efficiency and energy saving.

The object of the present invention is to provide a heating device of this type that satisfies the above requirements.

(Means for Solving the Problems) The present invention involves bringing the recording material into close contact with a heating body through a heat-resistant film, moving the heating body and the heat-resistant film relative to each other, and transferring the heat of the heating body through the heat-resistant film. The heating device is characterized in that at least the sliding surface of the heating body with the heat-resistant film is covered with a surface protective layer made of a resin having good heat resistance and sliding properties, such as a fluororesin. It is a heating device.

Further, in the heating device of the present invention, the coefficient of friction of the surface protective layer surface of the heating body against the inner surface of the film, which is the side facing the heating body of the heat-resistant film, is μm, and the surface of the heat-resistant film facing the recording material is The heating device is characterized in that μm<μ2, where μ2 is the coefficient of friction of the surface of the recording material with respect to the outer surface of the film, which is the surface on which the recording material is exposed.

(Function) If the above relationship between μm and μ2 is μm≧μ2, the heat-resistant film and the recording material may slip (the transport speed of the heat-resistant film is slower than the transport speed of the recording material). It is difficult to ensure that the heat-resistant film and the recording material are in close contact with each other at the heating body position, and the slippage causes disturbances in the image carried on the recording material. Heat resistant and
By coating with a surface protective layer made of a resin with good sliding properties, such as a fluororesin, the fluororesin has excellent heat resistance and a small surface friction coefficient (excellent sliding properties).
μm becomes smaller, μ2 becomes relatively larger, and it is possible to have a relationship of μm <μ2.

As a result, the heat-resistant film and the recording material are conveyed and passed through the heating body position in a stable and integral state with no slippage between them, and the recording material is heated without causing any image disturbance. be done.

Also, by reducing the micrometer size, the sliding resistance between the heating element and the heat-resistant film becomes smaller, which reduces the device drive torque, simplifies the device drive system, and reduces the overall size and cost of the device.・It becomes possible to make energy-saving keys, etc.

(Embodiment) The drawing shows an embodiment of the present invention (image heat fixing device 100).
).

(1) Overall schematic structure of the device 100 FIG. 1 is a cross-sectional view of the device 100, FIG. 2 is a longitudinal sectional view, FIGS. 3 and 4 are right and left side views of the device, and FIG. is an exploded perspective view of main parts.

1 is a horizontally elongated device frame (bottom plate) made of sheet metal and has an upward channel-shaped cross section; 2 and 3 are a left side wall plate and a right side wall provided integrally with the frame 1 at both left and right ends of the device frame 1; A plate 4 is an upper cover of the device, which is fitted between the upper ends of the left and right side wall plates 2 and 3, and its left and right ends are fixed to the left and right side wall plates 2 and 3 with screws 5, respectively. It can be removed by loosening and removing screw 5.

6 and 7 are vertical notched elongated holes formed symmetrically in the approximately central portions of the left and right side wall plates 2 and 3, and 8 and 9 are elongated holes 6 and 7, respectively.
A pair of left and right bearing members are fitted and engaged with the lower end portions of the bearing members.

Reference numeral 10 denotes a film pressure roller (pressure contact roller, backup roller) as a rotating body that sandwiches the film with a heating body to be described later to form a nip portion and drives the film. The left and right ends of the center shaft 11 are connected to the left and right bearing members 8, respectively.
・9 is supported by a bearing so that it can rotate freely.

Reference numeral 13 denotes a laterally elongated stay made of sheet metal, which serves as an inner kite member of the film 21 to be described later, and a supporting/reinforcing member for the heating body 19 and the heat insulating member 20 to be described later.

This stay 13 includes a horizontally long flat bottom part 14, and a front wall plate 15 and a rear wall plate 16 each having an outwardly curved cross section and extending in series from both long sides of the bottom part 14.
It has a pair of left and right horizontally extending lug parts 17 and 18 that project outward from both left and right ends of the bottom part 14, respectively.

Reference numeral 19 denotes a horizontally long low heat capacity linear heating body having a structure (FIG. 8) which will be described later.It is mounted and supported by a horizontally long heat insulating member 20, and the heat insulating member 20 is placed with the heating body 19 side facing downward. The stay 13 is integrally attached and supported in parallel to the lower surface of the oblong bottom surface portion 14.

21 is an endless heat-resistant film;
- It is externally fitted onto the stay 13 including the heat insulating member 20. The inner circumferential length of this endless heat-resistant film 21 and the outer circumferential length of the stay 13 including the heating element 19 and the heat insulating member 20 are larger than that of the film 21 by, for example, 3 mm. The stay 13 including the heat insulating member 20 is loosely fitted around the stay 13 with a margin of circumference.

22 and 23 connect the film 21 to the heating body 19 and heat insulating member 20
These are a pair of left and right film end regulating flange members that are fitted onto the stay 13 containing the stay 13 and then fitted onto and supported by the horizontally projecting lug portions 17 and 18 at the left and right ends of the stay 13.

The distance between the inner surfaces 22a and 23a of the flanges of the left and right pair of flange members 22 and 23 is set to be slightly larger than the width of the film 21.

24 and 25 are the pair of left and right flange members 22 and 23.
This is a horizontally extending lug portion that protrudes outward from the outer surface of the stay 13 side.
The left and right flange members 22 and 18 are fully fitted into insertion holes provided within the wall thickness of the horizontally extending lug portions 24 and 25 of the flange members 22 to 23, respectively.
I firmly support 23.

To assemble the device, remove the upper cover 4 from between the left and right side wall plates 2 and 3, and attach the film pressure roller 10 with the left and right bearing members 8 and 9 fitted in advance to the left and right ends of the shaft 11.
Fit and engage the left and right bearing members 8 and 9 into the vertical notched elongated holes 6 and 7 of the left and right side wall plates 2 and 3 from the open upper end, and insert the pressure roller 10 between the left and right side wall plates 2 and 3. , lower the receiver to the position where it can be stopped at the lower end of the left and right bearing members 8 and 9 or the elongated holes 6 and 7 (drop-in type).

Next, the intermediate assembly, in which the stay 13, the heating body 19, the heat insulating member 20, the film 21, and the left and right flange members 22 and 23 are preassembled in the relationship shown in the figure, is placed with the heating body 19 side facing downward and insulated. The left and right outward protruding ends of the member 20 and the horizontally extending lug portions 2 of the left flange members 22 and 23
4 and 25 are fitted and engaged into the vertical notched elongated holes 6 and 7 of the left and right side wall plates 2 and 3 from the upper end openings, respectively, to form the left and right side wall plates 2 and 3.
Insert the support between the support rollers and lower the support with the downward facing heating element 19 or film 21 in between until it hits the upper surface of the pressure roller 10 installed earlier and is stopped (drop-in type).

Coil springs 26 and 27 are provided on the upper surfaces of the lugs on the lugs 24 and 25 of the left and right flange members 22 and 23, respectively, which protrude through the elongated holes 6 and 7 on the outside of the left and right side wall plates 2 and 3. The ten cover 4 is supported and positioned in a protruding position and set vertically, and the outer projecting lug parts 28 and 29 provided on the left and right end sides of the upper cover 4 are attached to the upper ends of the coil springs 26 and 27 set above. While compressing the coil springs 26 and 27 between the lug parts 24, 28, 25, and 29, respectively, fit them into the specified positions between the upper ends of the left and right side wall plates 2 and 3, and tighten the left and right screws 5. Fix it between the side wall plates 2 and 3.

As a result, the stay 13, heating element 19, heat insulating member 20, film 21,
The entire left and right flange members 22 and 23 are pressed downward, and the heating body 19 and the pressure roller 10 or the film 21 are sandwiched between each longitudinal part thereof, and the longitudinal parts thereof are pressed almost equally with a total contact pressure of 4 to 7 kg, for example. is maintained.

Reference numerals 30 and 31 designate connectors for supplying power to the heating body 19, which are fitted to both left and right ends of the heat insulating member 2o that protrudes from the outside of the left and right side wall plates 2 and 3 through long holes 6 and 7.

Reference numeral 32 denotes a heated intrusion logite installed on the front wall of the apparatus frame 1, and a recording material sheet P (the first one) supporting a visible image (powder toner image) Ta as a heated material introduced into the apparatus. 7) is guided toward the nip portion (heat fixing portion) N between the heating body 19 and the pressure roller 10, which are in pressure contact with each other with the film 21 in between, between the film 21 and the pressure roller IO.

Reference numeral 33 denotes a heated material exit kite (separation kite) installed on the rear wall of the apparatus frame 1, and the recording material sheet that has passed through the nip is sent to the lower ejection roller 34 and the upper groove roller 38. Guide to the nip area.

The discharge roller 34 has both left and right ends of its shaft 35 rotatably supported between bearings 36 and 37 provided on the left and right side wall plates 2 and 3. The hook part 40 of the shaft 38 is formed by bending a part of the rear wall of the upper cover 4 inward.
The receiver is inserted into the container and brought into contact with the upper surface of the discharge roller 34 by its own weight and the pressure spring 41. The pinch roller 38 rotates as the discharge roller 34 rotates.

G1 is a roller shaft 11 that projects outward from the right side wall plate 3.
The first Kia stuck to the right end of the G3 is also the right side wall plate 3
A third gear G2 fixed to the right end of the discharge roller shaft 35 projecting outward from the shaft is a second gear as a relay gear pivotally attached to the outer surface of the right side wall plate 3, and is connected to the first gear described above. G1
It meshes with the third Kia G3.

The first Kia G1 receives a driving force from a drive Kia Go of a drive source mechanism (not shown), and the pressure roller 10 is rotationally driven in the counterclockwise direction in FIG. It is transmitted to the third gear G3 via the second gear G2, and the discharge roller 34 is also rotationally driven in the counterclockwise direction in FIG.

(2) Operation When the endless heat-resistant film 21 is not driven, the remaining part of the endless heat-resistant film 21 except for the part sandwiched between the nip N between the heating body 19 and the pressure roller 10 is shown in the enlarged view of the main part in FIG. Most of the entire circumference is tension-free.

When the drive is transmitted from the drive gear GO of the drive source mechanism to the first Kia G1 and the pressure roller 10 is rotationally driven in the counterclockwise direction in FIG. A feeding movement force is applied due to the frictional force with the pressure roller 10, and the endless heat-resistant film 21 moves clockwise while sliding on the inner surface of the film or the surface of the heating body 19 at approximately the same speed as the peripheral rotational speed of the pressure roller 10. It is driven to rotate and move.

In this driving state of the film 21, a pulling force f acts on a portion of the film upstream of the nip portion N in the film rotation direction, so that the film 21 is moved further than the nip portion N as shown by the solid line in FIG. Contact with the film inner surface kite portion on the upstream side in the film rotation direction and near the nip portion, that is, approximately the lower half surface portion of the outward arc curved front plate 15 as the film inner surface kite of the stay 13 on which the film 21 is externally fitted. It rotates without sliding.

As a result, the rotating film 21 rotates with tension acting on the film portion B from the starting point O of the contact sliding portion with the front plate 15 to the nip N on the downstream side in the film rotation direction. As a result, wrinkles are prevented from occurring on at least the film portion surface, that is, the film portion surface B near the recording material sheet entrance side of the nip portion N, and the film portion of the nip portion N by the action of the tension described above.

Then, while the film is driven and the heating element 19 is energized, the recording material sheet P carrying the unfixed toner image Ta as the material to be heated is rotated through the nip portion N while being guided by the entrance guide 32. Dynamic film 21 and pressure roller 10
When the recording material sheet P is introduced with the image bearing surface facing upward between
is in close contact with the surface of the film 21 and moves through the nip N together with the film 21, and in the process of moving and passing, the thermal energy of the heating element 19 that is in contact with the inner surface of the film at the nip N is transferred through the film. The toner image Ta applied to the recording material sheet P becomes a softened and fused image Tb.

After passing through the nip N, the self-edging material sheet P is separated from the film 21 surface in a state where the toner temperature is higher than the glass transition point, and is guided between the exit roller 34 and the pinch roller 38 through the exit kite 33 and out of the apparatus. Sent out. While the recording material sheet P exits the nip portion N, leaves the surface of the film 21, and reaches the discharge roller 34, the softened/melted toner image Tb is cooled and fixed as a solidified image TCL/.

In the above, the recording material sheet P introduced into the nip part N is under tension as described above, and is always in close contact with the unwrinkled film part surface and moves through the nip part N together with the film 21, so that wrinkles are avoided. To prevent uneven heating and fixing caused by a certain film passing through the nip portion N, and to prevent creases on the film surface.

The film 21 has a part N of its total circumference both when being driven and when being driven.
Or, since tension is applied only to B-N, that is, when not driven (Fig. 6), the film 21 is at the nip portion N.
Almost all of the remaining circumference except for the remaining part is tension-free, and during driving, tension acts only on the nip part N and the film part B near the recording material sheet entrance side of the nip part N, and the remaining part is tension-free. Since almost the entire circumference is tension-free, and a film with a short circumference can be used throughout, the drive torque required to drive the film is small, and the film device configuration, parts, and drive system are The configuration is simplified, smaller, and lower in cost.

Also, when the film 21 is not driven (FIG. 6) and when it is driven (FIG. 7),
(Fig. 2), since tension is applied to the film 21 only at part N or B-H of the entire circumference as described above, when the film is driven, the film 21 is placed on one side Q in the film width direction (Fig. 2). On the other hand, even if a shift toward MLR occurs, the shift force is small.

Therefore, the film 21 is moved Q or R to the left @
The edge is the flange inner surface 22a as a film end regulating surface of the left flange member 22, or the right edge or the right flange member 23.
(f) Even if the film is pressed against the thick inner surface 23a, the film bias force is small, so the rigidity of the film is sufficiently strong against the bias force, and the edge of the film may be buckled or damaged. do not have. In addition, since the means for regulating the deviation of the film only needs to be the simple flange members 22 and 23 as in the device of this embodiment, the device configuration can be simplified, downsized, and lowered in cost, making it inexpensive and highly reliable. Can configure devices.

In addition to the flange members 22 and 23 in the case of the device of this embodiment, for example, a rib made of heat-resistant resin is provided at the end of the film 21 in the circumferential direction of the endless film as the film deviation regulating means, and this rib is regulated. Good too.

Furthermore, the rigidity of the film 21 used can be reduced to compensate for the reduction in the biasing force as described above, so a thinner film with a smaller heat capacity can be used to improve the quick start performance of the device.

(3) Film 21 In order to reduce the heat capacity of the film 21 and improve quick start performance, the film thickness T of the film 21 is set to a total thickness of 10
A single layer or composite layer film having heat resistance, mold releasability, strength, durability, etc. of 0 μm or less, preferably 40 μm or less, and 20 μm or more can be used.

For example, polyimide polyetherimide (PEI)
・Polyether sulfone (PES) ・Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (
PFA)/Polyetheretherketone (PEEK)
・Polyparabanic acid (PPA) or composite layer film, for example, polyimide film with a thickness of 20 μm, at least on the image contact side
A 10 μm releasable coat layer made of fluororesin, silicone resin, etc. such as F-FEP, and additionally conductive materials (carbon black, graphite, conductive whiskers, etc.) added thereto.
It is something that has been applied thickly.

(4) Heating body 19 FIGS. 8(A) and 8(B) are partially cutaway planes of the surface side (the side facing the heat-resistant film 21) of the heating body 19 attached to the heat insulating member 20, respectively. and an enlarged cross-sectional view.

The substrate 19a is a member having heat resistance, electrical insulation, low heat capacity, and high thermal conductivity, and is, for example, an alumina substrate having a thickness of 1 mm, a width of 6 mm, and a length of 240 mm.

The heating element 19b is formed of, for example, Ag/Pd (silver palladium), Ta2 along the longitudinal direction approximately at the center of the surface of the substrate 19a.
Made of electrically resistive material such as N, RuO2, etc., about 10 μm thick and 1 width wide.
It is coated in the form of a line or strip of ~3 mm by screen printing or the like.

Conductive patterns 19d are formed as first and second power feeding electrodes on the surface of the substrate on both longitudinal ends of the heating element 19b.
- 19e are formed to be electrically connected to the ends of the heating elements.

The conductive pattern portions as the first and second power feeding electrode portions 19d and 19e are formed by coating, for example, by a screen printing method, and are made of a material with good conductivity, such as Au (gold).
These are Ag (silver) and Cu (copper).

Then, the heating element 19b, the first and second power feeding electrode parts 1
The surface of the substrate 19a on which the electrodes 9d and 19e are formed is coated with PFA (tetrafluoroethylene-peroxide) as a surface protective layer 19c, except for the surface portions on both ends of the substrate where the first and second power feeding electrode portions 19d are present. A layer of a fluororesin such as PTFE (polytetrafluoroethylene resin) (fluoroalkyl vinyl ether copolymer resin) is formed to a thickness of about 10 μm by coating or baking.

The heating body 19 having the above-mentioned structure is mounted and supported with the front side facing outward via the heat insulating member 2o on the bottom part 14 of the above-mentioned horizontally long stay 13 made of sheet metal as a support body.

In its attachment, in the supported state, the left and right ends of the heat insulating member 2o protrude outward from the left and right ends of the stay 13, and the power supply connectors 30 and 31 are fitted to the left and right outward protrusions.

The power supply connectors 30 and 31 are electrically connected to the first and second power supply electrode portions 19d and 19e, respectively, and are connected to a power supply circuit (not shown) via lead wires 30a and 31a, respectively.

As a result, the power supply circuit→Leet wire 30a→first power supply connector 30→first electrode part 19d of heating element 19→heating element 19b+second electrode part 19e→second power supply connector 31→Leet wire 31a → Heating element 19b in the path of the power supply circuit
Electricity is applied to the heating element 19, causing the heating element 19 to generate heat.

Although not shown in the figure, a temperature measuring element such as a low heat capacity thermistor or a low heat capacity temperature measuring resistor such as a PT film, or a safety element such as a fuse is provided on the back side of the heating body 19.

The heating element 19b of the heating element 19 of this example is energized at a predetermined timing by an image forming start signal.
b generates heat over approximately its entire length. AClooV is used for energization.
The supplied power is controlled by controlling the phase angle of energization by an energization control circuit (not shown) including a triac in accordance with the temperature detected by the thermometer.

The heating element 19 heats the substrate 1 by energizing the heating element 19b.
Since the heat capacity of the entire heating element 9a, heating element 19b, surface protection layer 19c, etc. is small, the temperature of the heating element surface rapidly rises to the required fixing temperature (for example, 140 to 200 DEG C.).

The heat-resistant film 21 in contact with the heating element 19 also has a small heat capacity, and the recording material sheet P is pressed against the film through the film 21 due to thermal energy on the heating element 19 side.
The image is effectively transferred to the side and thermal fixation of the image is performed.

As mentioned above, the surface temperature of the film facing the heating element 19 rises to a high enough temperature relative to the melting point of the toner (or the temperature at which it can be fixed to the recording material sheet P) in a short period of time, resulting in excellent quick start performance. There is no need for so-called standby temperature control, in which the temperature of the heating element 19 is raised in advance, and energy saving can be realized, and temperature rise inside the machine can also be prevented.

The heat insulating member 20 insulates the heating element 19 to make effective use of heat generated, and is made of materials having heat insulating properties and high heat resistance, such as pps (polyphenylene sulfide), PAI (polyamideimide), P (polyimide), etc. PEEK (
Polyetheretherketone), liquid crystal polymer, and other highly heat-resistant resins.

Therefore, as mentioned in the (effect) section above, the heating element 19
At least the sliding surface with the heat-resistant film 21 is covered with a surface protective layer 1 made of a fluororesin having good heat resistance and sliding properties, for example.
9c, the fluororesin surface protective layer 19c, which has a small surface friction coefficient and excellent heat resistance, prevents the heating element from touching the inner surface of the film, which is the surface of the heat-resistant film 21 facing the heating element 19. The coefficient of friction μ on the surface of the surface protective layer becomes smaller, and the coefficient of friction μ2 on the surface of the recording material relative to the outer surface of the film, which is the surface facing the recording material of the heat-resistant film, becomes larger, μm<μ2
The relational structure is as follows. Therefore, the heat-resistant film 21 and the recording material P can be conveyed and passed through the heating body position in a stable integral contact state without any slippage between the two, and the recording material can be heated without causing image holes. Processing is executed.

In addition, by reducing the micrometer, the sliding resistance between the heating element 19 and the heat-resistant film 21 becomes smaller, which reduces the driving torque of the device, which simplifies the drive system of the device and makes the device more compact and economical. It becomes possible to reduce costs and save energy.

The surface protection layer 19c made of fluororesin can also be formed using a heat-shrinkable tube of fluororesin.

FIG. 8(C) shows an example of this, which is a heat-shrinkable fluorine ladle whose inner circumference is appropriately larger than the cross-sectional circumference of a heating element substrate 19a on which a heating element 19b is formed. The heating body substrate 19a described above is inserted into a fat tube (thickness: approximately 20 μm, for example), and the tube is heat-shrinked in a heating furnace, so that the tube is brought into close contact with the entire circumferential surface of the substrate 19a. The sliding surface of the body 19 with the heat-resistant film 21 is covered with a surface protective layer 19c made of fluororesin, and the same effects as those shown in FIGS. 8(A) and 8(B) can be obtained.

(5) Example of Image Forming Apparatus FIG. 9 shows a schematic configuration of an example of an image forming apparatus incorporating the image heating fixing apparatus 100 shown in FIGS. 1 to 8.

The image forming apparatus of this example is a laser beam printer using a transfer type electrophotographic process.

PC is a process cartridge, which includes a rotating tram-type electrophotographic photoreceptor (hereinafter referred to as drum) 61 and a charger 62
- It includes four process devices: a developing device 63 and a cleaning device 64. This process cartridge can be attached to and removed from a predetermined position within the apparatus by opening the opening/closing part 65 of the apparatus and opening the inside of the apparatus.

The tram 61 is driven to rotate in the clockwise direction as indicated by the image forming start signal, and the surface of the rotating drum 61 is connected to the charger 62.
The drum is uniformly charged to a predetermined polarity and potential, and the charged surface of the drum is output from a laser scanner 66 using a laser beam modulated in accordance with time-series electric digital pixel signals of target image information. By performing main scanning exposure by the drum 67, electrostatic latent images corresponding to target image information are sequentially formed on the surface of the drum 61. The latent image is then developed as a toner image by a developing device 63.

On the other hand, the recording material sheets P in the paper feed cassette 68 are separated and fed one by one by the cooperation of the paper feed roller 69 and the separation pad 70, and are synchronized with the rotation of the tram 61 by a pair of registration rollers 71, and then transferred to the tram 61. and a transfer roller 72 that is in opposing pressure contact with the transfer roller 72 and is fed to a pressure nip 73 that is a fixing section,
The toner image on the drum 1 side is sequentially transferred onto the fed recording material sheet 81 side.

The recording material sheet P that has passed through the transfer section 73 is separated from the surface of the drum 61 and introduced into the fixing device 100 via a kite 74.
Through the operations and functions of the apparatus 100 described above, the unfixed toner image is heat-fixed and output from the output lower 5 as an image formed product (print).

The surface of the drum 61 from which the recording material sheet P has been separated through the transfer section 73 is subjected to removal of adhered contaminants such as untransferred toner by a cleaning device 64, and is used repeatedly for image formation.

The heating device of the present invention can be effectively utilized not only as an image heating and fixing device of the image forming apparatus described above, but also as an image surface heating and polishing device, a temporary fixing device, and the like.

It goes without saying that the configuration of the heating body 19 according to the present invention can also be applied to the heating body 19 of the heating device having the configuration shown in FIGS. 10 and 11 described above.

(Effects of the Invention) As described above, according to the present invention, in a film heating type heating device, the heating element is positioned so that the heat-resistant film and the recording material are in stable integral contact with each other without any slippage between the two. The recording material can be heated without causing any image disturbance.

In addition, the sliding resistance between the heating element and the heat-resistant film is reduced, which reduces the drive torque of the device, and simplifies the drive system of the device, resulting in overall downsizing, lower cost, and energy saving of the device. It becomes possible to aim for something, and the intended purpose is achieved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an embodiment of the device. Figure 2 is a longitudinal sectional view. Figure 3 is a right side view. Figure 4 is a left side view. FIG. 5 is an exploded perspective view of the main parts. FIG. 6 is an enlarged cross-sectional view of the main part showing the state of the film when not driven. FIG. 7 is the same diagram as above when driving. Figures 8 (A) and (B) are a partially cutaway plan view and an enlarged cross-sectional view of the surface side of the heating element attached to the heat insulating member, respectively, and Figure 8 (C) is an enlarged cross-sectional view of another configuration example. Surface diagram. FIG. 9 is a schematic configuration diagram of an example of an image forming apparatus. FIGS. 10 and 11 are schematic configuration diagrams of examples of image heating fixing devices using a film heating method, respectively. 19 is a heating element, 19c is a surface protective layer made of fluororesin, 20 is a heat insulating member, 21 and 51 are heat resistant films, 13
1 is a stay, and 10 is a roller as a rotating body. Patent applicant: Canon Co., Ltd. Kaya 6

Claims (3)

[Claims] (1) In a heating device in which a recording material is brought into close contact with a heating body through a heat-resistant film, the heating body and the heat-resistant film are moved relative to each other, and heat from the heating body is applied to the recording material through the heat-resistant film. The heating device is characterized in that at least the sliding surface with the heat-resistant film is coated with a surface protective layer made of a resin with good heat resistance and sliding properties. (2) The heating device according to claim 1, wherein the surface protective layer is made of fluororesin. (3) Let μ_1 be the friction coefficient of the surface of the surface protective layer of the heating body against the inner surface of the film, which is the surface of the heat-resistant film facing the heating body, and the film is the surface of the heat-resistant film facing the recording material. 2. The heating device according to claim 1, wherein μ_1<μ_2, where μ_2 is the coefficient of friction of the surface of the recording material with respect to the outer surface.