JPH0444076A - Heating device - Google Patents

Abstract

PURPOSE:To prevent a film from wrinkling owing to the displacement of a film part on a film end part side to the center part of the film by forming a pressure roller substantially in an inverted crown shape. CONSTITUTION:The film 21 is sandwiched with a heating body 19 to form a nip part N and the pressure roller 10 as a rotary body for driving the film is so shaped that the roller is not in a straight shape, but in the inverted crown shape in the length direction or substantially in the inverted crown shape having end parts cut 12a. Thus, the pressure roller 10 is formed in the inverted crown shape, so that the distribution of pressure applied to the film 21 by the roller at the nip part N with the heating body 19 is larger at the width-directional end parts of the film then at the center part. Forces from the center part to both end sides operate on the film 21, which is conveyed while unwrinkled. Consequently, the film is prevented from wrinkling and the wrinkling of a recording material sheet P can be prevented.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention introduces a recording material that supports a visible image on 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 heating device of a type (film heating type) in which the heat of the heating element is introduced into the record through the film by passing the heating element together with the film in close contact with the film.

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-melting resin, etc., by an appropriate image forming process means such as electrophotography, electrostatic recording, magnetic recording, etc. 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. It can be utilized as 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.

Further, it can be used, for example, in a device that heats a recording material carrying an image to modify its surface properties (to give it a gloss), and a device that performs a temporary adhesion 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 a bullet layer and pressed against 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, including a flash heating method, an oven heating method, a hot plate heating method, a heald heating method, and a high frequency heating method.

For example, in JP-A No. 63-3]3]82, the present applicant describes a fixedly supported heating body (hereinafter referred to as a heater) and a device that is conveyed (moved and driven) while being in pressure contact with the heater. It has a heat-resistant film and a pressure member that brings the recording material into close contact with the heater through the film. We have proposed a system and configuration for heating and fixing unfixed images on the recorded lunar surface, and have already put it into practical use.

More specifically, a thin heat-resistant film (or sheet)
a means for moving and driving the film; a heater disposed to fixedly support the film on one side of the film; The film has a pressure member that brings the visible image bearing surface of the recording layer into close contact with the recording layer through which the image is fixed. The recording material is moved at a substantially concave speed in the forward direction with respect to the recording layer to be recorded, and is passed through a nip portion as a fixing portion formed by pressure contact between a heater and a pressure member with the traveling film sandwiched therebetween. The developer image-bearing surface is heated by the heater through the film to apply thermal energy to the developer image (unfixed toner image) to soften and melt it, and then the film after passing through the fixing section and the recording layer are separated at a point. This is a heating means/device that is basically separated.

This kind of film heating type equipment uses a heating element with a fast temperature rise and a thin film, so it is possible to shorten wait time (quick start) and solve various drawbacks of conventional equipment. It has the following advantages and is effective.

FIG. 12 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 a fixing film or film), which is arranged below a driving roller 52 on the left side, a driven roller 53 on the right side, and between these driving rollers 52 and driven rollers 53. The three members 52, 53, and 54 of the low heat capacity linear heating body 54 are parallel to each other.
A suspension cable is installed in between.

The fixing film 51 is a heated material that carries on its upper surface an unfixed toner image Ta that is conveyed from the image forming section (not shown) at a predetermined circumferential speed in the opening direction as the drive roller 52 rotates clockwise. The recording layer sheet P is rotated at approximately the same peripheral speed as the conveyance speed (process speed) of the recording layer sheet P.

Reference numeral 55 denotes a pressure roller as a pressure member, which pinches the downward film portion of the endless belt-shaped fixing film 51 and presses it against the lower surface of the heating body 54 by a biasing means (not shown). , and rotates counterclockwise in the forward direction in the conveyance direction of the recording material sheet P.

The heating element 54 is a low heat capacity linear heating element whose length is the direction intersecting the plane movement direction of the film 51 (width direction of the film), and includes a heater substrate (base material) 56 and a current-carrying heating resistor (heating element) 57. - It is composed of a surface protection layer 58, a temperature measuring element 59, etc., and is fixedly supported by being attached to a support body 61 via a heat insulating material 60.

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 the Gytro 2 to the fixing film 51 at the pressure contact area N between the heating body 54 and the pressure roller 55. The unfixed toner enters between the pressure roller 55 and the unfixed toner image surface or 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, so that the unfixed toner is attached together with the film. It passes between the mutual pressure contact portion N between the heating body 54 and the pressure roller 55 in an overlapping state.

The heating body 54 is heated with electricity at a predetermined timing, and the thermal energy on the side of the heating body 54 is transmitted to the recording material sheet portion that is in close contact with the film through the film 51, and the toner image Ta passes through the pressure contact portion N. During this process, it is heated and becomes a softened and melted image Tb.

The rotationally driven fixing film 51 turns its traveling direction at a steep angle at the edge portion S of the heat insulating material 60 having a large curvature. Therefore, the recording sheet P conveyed through the pressure contact part N while overlapping with the fixing film 51 is transported to the edge part S.
The sheet is separated from the fixing film 51 by the curvature 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).

(Problems to be Solved by the Invention) The following problems have been raised with such a film heating type device.

In other words, in such a film heating type device, the film is moved relative to the heating element by being rotated by a drive source while being pressed against the heating element with the film in between, and sliding the inner surface of the film against the surface of the heating element to move the film to a predetermined position. In the case of a roller that is driven to move in the recording material conveyance direction at a speed of The pressure distribution in the direction was sometimes higher at the center than at the edges in the width direction of the film. In other words, the conveying force of the film by the roller is greater at the center than at the edges in the width direction of the film, and as the film is conveyed, a force acts on the film that causes it to stick to the portion of the film where the conveying force is smaller or the portion where the conveying force is greater. , the edge of the film may move toward the center of the film, causing wrinkles in the film.Furthermore, when a recording material sheet is introduced into the nip, the recording material sheet may be wrinkled as it passes through the nip. May cause wrinkles.

An object of the present invention is to provide a heating device that solves the above-mentioned problems regarding a heating device of a film heating type using an endless heat-resistant film.

(Means for Solving the Problems) The present invention provides a fixed heating body, an endless heat-resistant film whose inner surface is pressed against the heating body and is driven to move, and a film between the heating body and the heating body. A nip is formed by sandwiching the film, and a pressure roller is applied to press the recording material that supports the microscope image, which is introduced between the film and the outer surface of the film, to the heating body through the film. The pressure roller is a roller that is in pressure contact with the heating body with the film in between and is rotationally driven by a drive source to slide the inner surface of the film on the surface of the heating body and drive the film to move at a predetermined speed in the recording material conveyance direction, and A heating device characterized in that the roller is substantially in the shape of an inverted crown.

It is.

(Function) (1) When the film is driven and the heating element generates heat, a nip formed between the heating element and the pressure roller with the film sandwiched between the film and the pressure roller. When the recording material is introduced with the image-bearing side facing the film,
The recording material is in close contact with the outer surface of the film and moves through the nip together with the film, and in the process of moving and passing, the thermal energy of the heating element that is in contact with the inner surface of the film at the nip is applied to the recording material through the film. The recording material supporting the visible image is then heat-treated using a film heating method.

(2) The pressure contact member that presses the film against the heating body is rotated by a drive source while holding the film in pressure contact with the heating body, and slides the inner surface of the film against the surface of the heating body while moving the film at a predetermined speed in the recording material conveyance direction. By using a roller body that is driven to move, it is possible to reduce the shifting force applied to the film, and it is also possible to improve the position of the roller body and the positional accuracy of the kia for driving the roller body. Therefore, the device structure can be simplified, the device can be made inexpensive and highly reliable, and the total circumference length of the endless film used can be shortened.

(3) Also, by forming the pressure roller 10 into an inverted crown shape, the pressure distribution in the width direction of the film applied by the roller to the film at the nip with the heating element is distributed between the ends of the film in the width direction and the center of the film. As a result, a force acts on the film from the center toward both ends, that is, the film is conveyed while receiving the effect of smoothing out wrinkles, preventing wrinkles on the film and introducing it into the nip section. It is possible to prevent wrinkles from forming on the recording material sheet P.

(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.

Reference numeral 1 indicates a horizontally elongated device frame (bottom plate) made of sheet metal and has an upward channel (groove) cross section; 2 and 3 indicate a left side wall plate and a right side wall provided on the frame 1 at both left and right ends of the device frame 1; Plate 4 is the upper cover of the device, and left and right side wall plates 2
・Insert between the upper ends of 3 and leave the left and right ends respectively! 〒
It is fixed to the side wall plates 2 and 3 with screws 5. It can be removed by loosening and removing the 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.
These are a pair of left and right bearing members that are fitted into the lower end of the bearing member.

Reference numeral 10 designates 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 horizontally 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 consists of a horizontally long flat bottom part 14, a face wall plate 15 and a rear wall plate 1, each of which stands in series from both longitudinal sides of the bottom part 14 and has an outwardly curved cross section.
6, and a pair of left and right horizontally projecting lug portions 17 and 18 that project outward from both left and right ends of the bottom surface portion 14, respectively.

19 is a horizontally long low heat capacity 1 having the structure described later (Fig. 6).
It is a linear heating element, and is mounted and supported by a horizontally long heat insulating member 20, and this heat insulating member 20 is integrally mounted parallel to the lower surface of the horizontally long bottom surface portion 14 of the stay 13 with the heating body 19 side facing downward. Installation is supported.

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 the 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 such that the film 21 is larger, for example, by 3 mm. Ste including the heat insulating member 20=
Compared to No. 13, the circumferential length is loosely fitted.

22 and 23 connect the film 21 to the heating body 19 and heat insulating member 20
After being fitted onto the stay 13 containing As will be described later, the distance G (FIG. 8) between the inner surfaces 22a and 23a of the concave seats of the pair of left and right flange members 22 and 23 is set slightly larger than the width C (the same) of the film 21. It is.

24 and 25 are the pair of left and right flange members 22 and 23.
The outward horizontally extending lug parts 17 and 18 on the stay 13 side are the horizontally extending lug parts 24 and 18 of the flange members 22 and 23, respectively. It fully fits into the insertion hole provided within the wall thickness of 25, and firmly supports each of the left and right flange members 22 and 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 outwardly projecting ends of the member 20 and the horizontally extending lug portions 2 of the left and right flange members 22 and 23
4 and 25 into the vertical notch slots 6 of the left and right side wall plates 2 and 3, respectively.
・Fit and engage 7 from the upper end open part and insert it between the left and right side wall plates 2 and 3, and the downward heating element 19 hits the upper surface of the pressure roller 10 installed earlier with the film 21 in between, and the receiver stops. (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 upper cover 4 is positioned vertically with support protrusions, and the outer projecting lug parts 28 and 29 provided at the left and right ends 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 predetermined positions between the upper ends of the left and right side wall plates 2 and 3. Fix it between the left and right 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 were pressed downward, and the heating body 19 and the pressure roller 10 were brought into contact with each other approximately equally in the longitudinal direction with the film 21 in between, for example, with a total contact pressure of 4 to 7 kg. held in state.

Reference numerals 30 and 31 designate power supply connectors for supplying power to the heating element 19, which are fitted to both left and right ends of the heat insulating member 20, which protrudes from the outside of the left and right side wall plates 2 and 3 through long holes 6 and 7, respectively.

Reference numeral 32 denotes a heated material artificial kite attached to the front wall of the apparatus frame 1, and a recording material sheet P (the first 7) between the heating body 19 and the pressure roller 10, which are pressed against each other with the film 21 in between (heat fixing section)
It is guided between the N film 21 and the roller 10.

Reference numeral 33 denotes a heated ejection rocker (separator kite) installed on the rear wall of the apparatus frame 1, which collects the recording material sheet that has passed through the nip portion between the lower discharge roller 34 and the upper groove roller 38. guide to the nip part.

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 pinch roller 38 has its shaft 39 connected to the hook portion 4 formed by bending a part of the rear wall of the cover 4 inward.
The receiver is placed in the position 0 and is brought into contact with the upper surface of the discharge roller 34 by its own weight and the push spring 41. This donchikoro 38
is rotated by the rotational drive of the discharge roller 34.

G1 is a roller shaft 11 that projects outward from the right side wall plate 3.
The first gear, G3, is fixed to the right side of 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 serving 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 driving force from the 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 (no tension is applied).

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 the inner surface of the film slides on 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 the portion of the film on the side of the film rotation direction]L than the nip portion N, so that the film 21 is moved to the nip portion N as shown by the solid line in FIG. For the inner surface guide portion of the film located upstream in the film rotation direction and near the nip, that is, approximately the lower half surface portion of the outwardly curved front plate 15 serving as the inner surface guide of the stay 13 on which the film 21 is externally fitted. It contacts and rotates while producing sliding motion.

As a result, the rotating film 21 rotates with tension acting on the film portion B from the starting point 0 of the contact sliding portion with the front plate 15 to the nip portion N on the downstream side in the film rotation direction. In this case, the occurrence of wrinkles at least on the film part surface, that is, the film part surface B near the recording paper sheet entrance side of the nip part N, and the film part in the nip part N is prevented by the action of the above-mentioned tension.

Then, in the state where the film is driven and passed through the heating body 19, the recording material sheet P carrying the unfixed toner image Ta as the material to be heated is guided by the population guide 32 to the nip portion N. rotating film 21 and pressure roller 1
When the recording material sheet P is introduced with the image bearing surface facing upward between the film 21 and the film 21, the recording material sheet P comes into close contact with the surface of the film 21 and moves through the nip part N together with the film 21. The heating element 19 is in contact with the inner surface of the film at
Thermal energy is applied to the recording material sheet P via the film, and the toner image Ta becomes a softened and fused image Tb.

The recording material sheet P that has passed through the nip portion N is removed from the film 21 in a state where the toner temperature is higher than the glass transition point, is guided by the exit kite 33 between the discharge roller 34 and the binge roller 38, and is sent out of the apparatus. It will be done. Recording material sheet P
The softened/melted toner image Tb is cooled, converted into an assimilated image TC, and fixed while leaving the nip portion N, stiffening from the film 21, and reaching the discharge roller 34.

As described above, the recording material sheet P introduced into the nip portion N is under tension and moves in the nip portion N together with the film 21 while always being in close contact with the unwrinkled film surface, thereby eliminating wrinkles. There is no occurrence of heating unevenness/fixing unevenness or creases on the film surface due to a situation where a certain film passes through the nip portion N.

The film 2J 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.
Most of the remaining part, except for the entire circumference, is tension-free, and even during driving, tension acts only on the nip part N and the film part B near the recording material sheet entry point 1 of the nip part N, and the remaining part is tension-free. Since most of 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,
The drive system 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),
2), tension is applied to the film 21 only on part N or B-N of the entire circumference as described above, so when the film is driven, the film 21 is applied to one side Q in the film width direction (Fig. 2) or Even if a shift toward the other side R occurs, the shift force is small.

Therefore, the film 21 shifts Q or R and its left edge becomes the same seat inner surface 22a as the film end regulating surface of the left flange member 22, or the right edge or the right edge of the right flange member 23.
Even if the film comes into contact with the inner surface 23a of the seat, since the film biasing force is small, the rigidity of the film sufficiently overcomes the biasing force and no damage such as buckling or breakage of the film ends occurs. 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 also 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 device of this embodiment, for example, a rib made of heat-resistant resin may be provided at the end of the film 21 in the circumferential direction of the endless film, and this rib may be used as the film deviation regulating means. It's okay.

Furthermore, as the film 21 used, the rigidity can be reduced by the amount of the drop in the biasing force as described above, so it is possible to use a thinner film with a smaller heat capacity to improve the quick start performance of the device. .

(3) Regarding 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)-
Polyetherimide: / (PES) Tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA) ・Polyether ether ketone (PEEK)
) ・Polyparabanic acid (PPA) or PTFE (tetrafluoroethylene resin) at least on the image contact side of a composite layer film such as a 20 μm thick polyimide film
A 10 μm releasable coat layer made of fluororesin, silicone resin, etc. such as PAF-FEP, and a conductive material (carbon black, graphite, conductive whiskers, etc.) added thereto.
It is a thickly applied texture.

(4) Regarding the heating body 19 and heat insulating member 20.

The heating element 19, similar to the heating element 54 of the apparatus shown in FIG. 12, is composed of a heater substrate 19a (see FIG. 6), an energized heating resistor (heating element) 19b, a surface protection layer 19c, a temperature measuring element 19d, and the like.

The heater board 19a is a heat resistant, insulating, low heat capacity, and high thermal conductive member, and has a thickness of 1 mm and an I'110, for example.
It is an alumina substrate with a length of 240 mm.

The heating element 19b is located on the lower surface of the heater board 19a (film 21
For example, Ag
An electrically resistive material such as /Pd (silver palladium), Ta2N, RuO2, etc. is coated with a thickness of approximately 10 μm-1 in the form of a line or strip of 1 to 3 mm by screen printing or the like, and then a heat-resistant layer 19c is applied to the surface protection layer 19c. Approximately 10μ of glass
M coated.

The temperature sensing element 19d is, for example, the upper surface of the heater board 19a (
It is a low heat capacity temperature measuring resistor such as a PT film, which is coated by screen printing or the like on the substantially central part of the surface opposite to the surface on which the heating element 19b is provided. Thermistors with low heat capacity can also be used.

In the case of the heating element 19 of this example, the heating element 19b having a linear or narrow strip shape is energized at a predetermined timing in response to an image formation start signal to cause the heating element 19b to generate heat over substantially its entire length.

The power supply is AClooV, and the supplied power is controlled by controlling the phase angle of the current supply by a power supply control circuit (not shown) including a triac according to the temperature detected by the temperature measuring element 19c.

When the heating element 19 is energized, the surface of the heating element reaches a required fixing temperature (for example, 14
The temperature rises rapidly from 0 to 200°C.

The heat-resistant film 21 in contact with the heating element 19 also has a small heat capacity, and the recording material sheet 2 in pressure contact with the film via the heating element 19 receives thermal energy from 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 heating element 19 is warmed up, 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), FAI (polyamideimide), P■ (polyimide), PEEK (
Polyetheretherketone), liquid crystal polymer, and other highly heat-resistant resins.

(5) Regarding film width C and nip length.

As shown in the dimensional relationship diagram in FIG. 8, when the width of the film 21 is C and the length of the nip formed by pressure contact between the heating body 19 and the pressure roller 10 as a rotating body with the film 21 in between. , C<D.

That is, contrary to the above, when the film 21 is conveyed by the roller 10 with the relational configuration of C20, the film conveying force (pressing force) received by the film portion within the nip length area and the film outside the nip length area are The inner surface of the former film portion is slidably transported in contact with the surface of the heating element 19, while the inner surface of the latter film portion is made of a different material from the surface of the heating element 19. Heat insulation member 20
Since the film 210 is slidably conveyed in contact with the surface thereof, there is a risk that damage such as wrinkles or folds may occur at both ends of the film 210 in the width direction during the film conveyance process.

On the other hand, by setting the relational structure of C<D, the inner surface of the entire length region C in the width direction of the film 21 contacts the surface within the length range of the heating element 19 and slides on the surface of the heating element. Since the film is transported, the film transport force is made uniform over the entire length region C in the width direction of the film, thereby avoiding the problem of film end damage as described above.

Furthermore, since the pressure roller 10 used as a rotating body in this embodiment is made of a rubber material with excellent elasticity such as silicone rubber,
When heated, the coefficient of friction of the surface changes. Therefore, when the length range dimension of the heating element 19b of the heating element 19 is E, the friction coefficient between the roller 10 and the film 21 at the portion corresponding to the length range E of the heating element 19b,
The coefficient of friction between the roller 10 and the film 21 differs in a portion corresponding to the outside of the length range E of the heating element 19b.

However, by setting the dimensional relationship configuration of E<C<D, the difference between the length range E of the heating element 19b and the film width C can be reduced, so that the difference between the length range E of the heating element 19b and the film width C can be reduced. The influence of the difference in friction coefficient between the roller 10 and the film 21 on the transport of the film can be reduced.

Thereby, it becomes possible to stably drive the film 21 by the roller 10, and it becomes possible to prevent damage to the ends of the film.

Flange members 22 and 23 as film end regulating means
The film edge regulating surfaces 22a and 23a are within the length range of the pressure roller 10, and even if the film shifts, the film edges are prevented from being damaged.

(6) Regarding the pressure roller 10.

The pressure roller 10, which forms a nip N with the film 21 sandwiched between it and the heating body 19 and serves as a rotating body for driving the film, is made of a rubber elastic body with good #-shape, such as silicone rubber, for example. 9 (A) or (
It may have an inverted crown shape as shown in the exaggerated model diagram B), or it may have a substantially inverted crown shape with a cut 12a at the end of the inverted crown.

The degree d of the inverted crown is preferably set to d - 100 to 200 μm when the effective length H of the roller 10 is, for example, 230 mm.

In other words, in the case of a straight shape, the pressure distribution in the film width direction applied to the film 21 by the roller at the second lug portion N with the heating body 19 will be more concentrated in the center than in the widthwise ends of the film due to variations in component precision. Sometimes it was higher. In other words, the conveying force of the film by the rollers is greater at the center than at the ends in the width direction of the film, and as the film 21 is conveyed, a force is exerted on the film 21 that causes the portion of the film with a smaller conveying force to approach the portion of the film with a larger conveying force. , the edges of the film may move toward the center of the film, causing wrinkles on the film.
Furthermore, when the recording material sheet P is introduced into the nip portion N, wrinkles may occur in the recording material sheet P during the conveyance process through the nip portion.

On the other hand, by forming the pressure roller 10 into an inverted crown shape, the pressure distribution in the film width direction applied by the roller to the film 21 at the nip N with the heating element 19 is opposite to the above case. The edges in the width direction are larger than the center, and as a result, a force acts on the film 21 from the center toward both ends 1, that is, the film 21 is conveyed while being subjected to a wrinkle smoothing effect, and the wrinkles of the film are removed. In addition, it is possible to prevent wrinkles on the introduced recording material sheet P.

The pressure roller 10 as a rotary body presses the film 21 against the heating body 19 by sandwiching the film 21 between it and the heating body 19 as in the apparatus of this embodiment, and drives the film 21 to move at a predetermined speed to When a recording material sheet P as a heated material is introduced between the film 21 and the film 21, the recording material sheet P is brought into close contact with the surface of the film 21, pressed against the heating body 19, and driven to move together with the film 21 at a predetermined speed. By using it as a member, it is possible to reduce the biasing force applied to the film, and it is also possible to improve the positional accuracy of the roller 10 and the gear for driving the roller.

That is, the film 21 or the film 2
1 and the recording material sheet P, and a drive function to move and drive the film 21, are provided by separate pressurizing rotary bodies (the necessary pressurizing force is obtained by pressurizing these rotary bodies). ) and a film drive function rotating body, if the alignment between the heating body 19 and the film drive function rotary body goes out of alignment, a large biasing force in the width direction will be applied to the thin film 21. As a result, the edges of the film 21 may be damaged, such as folds or wrinkles.

In addition, a heating body 1 is attached to the pressurizing rotary body that also serves as a film drive member.
When applying the pressure necessary for pressure contact with 9 by pressing with a spring or the like, the position of the rotating body and the positional accuracy of the gear for driving the rotating body must be determined.

On the other hand, as described above, a pressure force necessary for fixing is applied to the heating body 19, and the recording material sheet P is pressed against the film 21 by the pressure roller 10, which is a rotating body.
By driving the recording material sheet P and the film 21 at the same time, the above-mentioned effects can be obtained, and the structure of the apparatus can be simplified, making it possible to obtain an inexpensive and highly reliable apparatus.

The configuration in which the roller 10 has the function of pressing the film 21 against the heating body 19 and the function of driving the film 21 is suitable for a film tension-free type device (at least a portion of the film 21 is a non-film device) like the device of this embodiment. A device in which no tension is applied either during the drive or when the film is being driven), a film tension type device (such as the device shown in Fig. 13 above, in which a film with a long circumference is always tensioned all the way around the device) The same action and effect can be achieved by applying the same function and effect to any type of film shift control means, sensor/solenoid method, rib control method, film edge (both sides or one side) control method, etc. However, it is particularly suitable for application to tension-free type devices.

(7) Regarding recording material sheet ejection speed.

The conveyance speed of the recording material sheet P as a heated material introduced into the nip portion N by the pressure roller 10 (rotating body), that is, the circumferential speed of the roller 10 is assumed to be 10, and the recording material sheet υ1 output of the discharge roller 34 is When the conveying speed, that is, the circumferential speed of the discharge roller 34 is VB2, it is better to set the speed relationship to be VIO>VB2. The speed difference may be set to several percentages, for example, about 1 to 3%.

When the maximum width of the recording material sheet P that can be introduced into the apparatus and used is F (see FIG. 8), in relation to the width C of the film 21, under the condition of F<C, VtO≦V3.
4, the recording material sheet P that is being conveyed astride between the nip portion N and the ejection roller 34 has a portion of the sheet that is passing through the nip portion N that is conveyed between the nip portion N and the ejection roller 34.
pulled by.

At this time, the film 21 whose surface is coated with PTFE or the like having good mold releasability is being conveyed at the same speed as the pressure roller 10.

In addition to the conveyance force by the pressure roller 10, a tensile conveyance force by the discharge roller 34 is also applied to the recording paper sheet P.
It is transported at a speed faster than the circumferential speed of the pressure roller 10. In other words, at the nip portion N, the recording material sheet P and the film 21
causes a slipping condition, which causes the recording layer sheet P
During the process of passing through the nip N, there is a possibility that the unfixed toner image Ta (FIG. 7) or the softened and melted toner image Tb on the recording material sheet P is disturbed.

Therefore, as described above, by setting the circumferential speed VIO of the pressure roller 10 and the circumferential speed V34 of the discharge roller 34 in the relationship of VIO>VB2, the recording material sheet P and the film 2
1, since only the conveying force of the pressure roller 10 is applied to the sheet P without the tensile force of the discharge roller 34 acting on the sheet P.
The occurrence of the above-mentioned image disturbance can be easily prevented due to slippage between the sheet P and the film 21.

In this embodiment, the discharge roller 34 is provided on the side of the heating device 100, but it may be provided on the side of the main unit, such as an image forming apparatus into which the heating device 100 is incorporated.

(8) Regarding the film edge regulation flange spacing.

The inner surface 22 of the pair of left and right flange members 22 and 23 as film end regulating means serves as a film end regulating surface.
When the distance between a and 23a is G (FIG. 8), the relationship with the width C of the film 21 may be set such that C<G. For example, when C is set to 230 mm, G is set approximately 1 to 3 mm larger.

That is, the film 2 has a thickness of, for example, 200 mm at the nip portion N.
It expands upon receiving the heat from the heating element 19 at a temperature close to 0.degree. C., and its dimension C increases. Therefore, if the width dimension C of the film 21 and the flange spacing dimension G at room temperature are set to C=G, and both ends of the film 21 are regulated by the flange members 22 and 23, the thermal expansion of the film described above occurs when the device is in operation. By C>
produces the state G. Since the film 21 is a thin film of about 50 μm, for example, in the COG state, the film end regulating surfaces 22a and 23a of the flange members 22 and 23
The film end contact pressure (for the @ part) increases, and the end is not able to withstand it and suffers damage such as bending and buckling. Since the frictional force between the film end regulating surfaces 22a and 23a of the flange members 22 and 23 also increases, the film conveyance force also decreases.

By setting the dimensional relationship C<G, even if the film 21 expands due to heating, the gap (G-C
) is provided between both ends of the film 210 and the film end regulating surfaces 22a and 23a of the flange member, thereby preventing both ends of the film 21 from coming into contact with the film end regulating surfaces 22a and 23a of the flange member at the same time.

Therefore, even if the film 21 expands thermally, the film end pressure contact force does not increase, making it possible to prevent the end portions of the film 21 from being tampered with and also to reduce the film driving force.

(9) Regarding the friction coefficient relationship between each member.

a, roller (rotating body) 1 against the outer peripheral surface of the film 21
0 surface friction coefficient μm, b Friction coefficient of the heating body 19 surface against the inner peripheral surface of the film 21 μ2, Friction coefficient of the roller 10 surface against the C8 heating body 19 surface μ3, d, Recording material as heated material The coefficient of friction of the outer circumferential surface of the film 21 against the surface of the sheet 2 is μ4, e Record old sheet 1
- The coefficient of friction of the surface of the roller 10 with respect to the surface of P is μ5, f, the maximum length in the transport direction of the recording material sheet P introduced into the device is 21, g, and the device is used as an image heat fixing device in a transfer type image forming device. In the case where the recording material sheet (transfer material) P is conveyed from the image transfer means part to the nip part N of the apparatus as an image heat fixing device, it is assumed that the temperature is 2°C.

Therefore, the relationship between μm and μ2 is μm〉μ2 The relationship structure is as follows.

That is, in this type of film heating type device, the relationship between μ4 and μ5 is set as μ4<μ5, and in the image forming device, the relationship between 1 and °C2 is set as I21>f1.
2.

At this time, if μm≦μ2, the film 21 and the recording material sheet P slip in the cross-sectional direction of the heat fixing means (the conveying speed of the film 21 is slower than the circumferential speed of the roller 10).
The toner image on the recording material sheet is disturbed during heat fixing.

In addition, if the recording material sheet P and the film 21 slip together (the transport speed of the film 21 and the recording material sheet P is delayed relative to the peripheral speed of the roller 10), in the case of a transfer type image forming apparatus, the image transfer When the toner image is transferred onto the recording sheet (transfer material) in the means section, the toner image on the recording material is also disturbed.

2, by setting μm>μ2, the film 21 and the recording material sheet P with respect to the roller 10 in the cross-sectional direction
can prevent slipping.

Furthermore, regarding the width C of the film 21, the length H of the roller 10 as a rotating body, and the length H of the heating body 19, under the conditions of C<H and C<D, the relationship configuration is μm>μ3. Make it.

That is, in the relationship of μm≦μ3, in the width direction of the heat fixing means,
The film 21 and the roller 10 slip, and as a result, the film 21 and the recording material sheet P slip, and the toner image on the recording material sheet is disturbed during heat fixing.

By establishing the relationship μm>μ3 as described above, it is possible to prevent the film 21 from slipping against the roller 10 in the width direction, particularly on the outside of the recording material sheet P.

By setting μm>μ2 and μm>μ3 in this way,
The conveyance speed of the film 21 and the recording material sheet P can always be made the same as the peripheral speed of the roller IO, and image holes can be prevented during fixing or transfer, and μm>μ
2. By performing μm>μ3 at the same time, roller i
It becomes possible to always make the peripheral speed (=process speed) of o and the conveying speed of the film 21 and the recording material sheet P the same, and a stable fixed image can be obtained in the transfer type image forming apparatus.

(10) Regarding film shift control.

The film shift control of the embodiment apparatus shown in FIGS. 1 to 9 is carried out by disposing a pair of left and right flange members 22 and 23 on both ends of the film 21 in the width direction for use in controlling the ends of the film. This is to cope with the deviation movement QH of the film (film both-side edge regulation type), but the following configuration is also effective as a film one-side edge regulation type.

In other words, the drive side of the left and right pressure coil springs 26 and 27 is set so that the direction in which the film is shifted in the width direction is always either leftward Q or rightward R. By setting the pressing force f27 of the spring 27 to be higher than the pressing force f26 of the spring 26 on the non-driving side (f27>f26), the film 21 is always moved toward the right side R, which is the driving side. Alternatively, the shape of the heating element 19 and the shape of the roller 10 can be changed on the driving end side and the non-driving end side to control the film conveyance force so that the film always shifts in one direction. The end of the film on the closer side is regulated by means such as a flange member as a regulating member for the film end on that side, a film rib and an engagement guide member, etc. In other words, in the apparatus shown in FIG. By regulating only the end portion of the shifting side (R0') using the regulating member 27, it becomes possible to stably and easily control the shifting of the film. As a result, when the apparatus is an image heat fixing apparatus, a stable and good fixed image can always be obtained.

Furthermore, since the endless film 21 is driven by the pressure roller 10 forming the nip portion N, no special driving roller is required.

These effects can be obtained both in the case of a tension-type device configuration in which the film is driven by applying tension all around it, and in the case of a tension-free type device configuration like the device of this embodiment. However, the means configuration is particularly suitable for tension-free types.

(11) Example of Image Forming Apparatus FIG. 11 shows a schematic configuration of an example of an image forming apparatus incorporating the image heating fixing apparatus 100 shown in FIGS. 1 to 9.

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

60 is a process cartridge, which includes a rotating drum 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 drum 61 is rotationally driven 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.
A laser beam 67 is uniformly charged to a predetermined polarity and potential by a drum, and is outputted from a laser scanner 66 to the charged surface of the drum, and is modulated in accordance with a time-series electric digital pixel signal of target image information. As a result of main scanning exposure, electrostatic latent images corresponding to target image information are sequentially formed on the surface of the drum 61. The latent image is then developed into a toner image by a developing device 63.

On the other hand, the recording material sheet P in the paper feed cassette 68 is fed in sections by the paper feed roller 69 and the dividing pad 70,
The recording material sheet is synchronized with the rotation of the drum 61 by a pair of registration rollers 71, and is fed to a pressure nip portion 73 which is a fixing portion between the tram 61 and a transfer roller 72 that is in pressure contact with the tram 61, and the two sides of the fed recording material sheet are coated with the drum. The toner images on the first side are sequentially transferred.

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 by a guide 74.
The unfixed toner image is heat-fixed by the operation and action of the device 100 described above, and is outputted 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 and a temporary fixing device.

(Effects of the Invention) As described in 1- below, the film heating type heating device of the present invention can prevent the occurrence of wrinkles in the film, resulting in a stable and reliable device. By pressing and moving the film against the heating body using a pressure roller, the configuration of the device can be simplified and downsized, and costs can be reduced.

[Brief explanation of drawings]

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. FIG. 8 is a dimensional relationship diagram of the constituent members. FIGS. 9(A) and 9(B) each show a roller 10 as a rotating body.
An exaggerated shape diagram showing an example of the shape. FIG. 10 is a longitudinal cross-sectional view of an example of a device that regulates one end of the film. FIG. 11 is a schematic configuration diagram of an example of an image forming apparatus. FIG. 12 is a schematic diagram of a known example of a film heating type image heating fixing device. 19 is a heating body, 21 is an endless film, 13 is a stay, and 10 is a roller as a rotating body.

Claims (1)

[Claims] (1) A fixed heating body, an endless 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 to form a nip portion, and the nip portion is formed by sandwiching the film between the heating body and the heating body. A pressure roller is provided between the outside surface of the film and the recording material supporting the visible image, and the pressure roller presses the recording material supporting the visible image against the heating body through the film. A roller that is rotationally driven by a drive source while being in pressure contact to slide the inner surface of the film on the surface of the heating element and drive the film to move at a predetermined speed in the recording material conveying direction,
and the roller has a substantially inverted crown shape.