JP2884714B2 - Image heating device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention introduces a recording material for supporting a visible image on a surface of a heat-resistant film, which is pressed against a heating body and moved and moved, on the side opposite to the heating body side. The present invention relates to an image heating apparatus of a system (film heating system) in which heat of a heating body is applied to an introduced recording material via a film by passing the heating body together with a film through the heating body.

This apparatus is composed of an image heating and fixing device in an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, etc., that is, a resin which can be heated and melted by an appropriate image forming process means such as electrophotography, electrostatic recording and magnetic recording. Recording material (transfer material sheet, electrofax sheet,
An unfixed toner image corresponding to the target image information, formed on the surface of an electrostatic recording sheet, printing paper, etc.) by the indirect (transfer) method or the direct method is permanently attached to the recording material surface carrying the image. The present invention can be used as an image heat fixing device for performing heat fixing processing as a fixed image.

Further, for example, the present invention can be used for an apparatus for improving the surface properties (such as polishing) by heating a recording material carrying an image, and for an apparatus for performing a temporary fixing treatment.

(Background Art) Conventionally, for example, a heating device for a recording material for fixing an image by heating includes a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and pressing against the heating roller. A heat roller method of heating a recording material while nipping and conveying the recording material is often used.

In addition, various methods 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 are known.

On the other hand, the present applicant has disclosed in Japanese Patent Application Laid-Open No. 63-313182, for example, a fixedly supported heating element (hereinafter referred to as a heater).
A heat-resistant film that is conveyed (moved and driven) while being in opposing pressure contact with the heater; and a pressing member that causes the recording material to be in close contact with the heater via the film, and records the heat of the heater through the film. An apparatus having a method and a configuration for heating and fixing an unfixed image formed and carried on a recording material surface to a recording material surface by applying the recording medium to the recording material surface has been proposed and has already been put to practical use.

More specifically, a thin heat-resistant film (or sheet), a means for driving the movement of the film, a heater fixedly supported and disposed on one side with the film in the middle, and a heater disposed on the other side A pressurizing member disposed opposite to the heater to bring a visible image bearing surface of a recording material to be image-fixed through the film into close contact with the heater, wherein the film is at least at the time of performing image fixing; The recording material to be image-fixed conveyed and introduced between the paper and the pressing member, is moved in the forward direction at substantially the same speed, and is formed by pressing the heater and the pressing member with the moving film therebetween. By passing through the nip portion as a part, the developed image carrying surface of the recording material is heated by the heater through the film to apply thermal energy to the developed image (unfixed toner image) to soften and melt the image, Then after passing through the fixing section A heating means or apparatus which is based on that to separate the film and the recording material at the separation point.

In such an apparatus of the film heating system, the use of a heating element and a thin film with a rapid rise in temperature makes it possible to shorten the weight time (quick start).
It has advantages such as being able to solve various disadvantages of the conventional device,
It is effective.

FIG. 13 shows a schematic configuration of an example of this type of image heating and fixing apparatus using an endless film as a heat resistant film.

Reference numeral 51 denotes an endless belt-shaped heat-resistant film (hereinafter, referred to as a fixing film or simply a film), which includes a left driving roller 52, a right driven roller 53, and a lower portion between the driving roller 52 and the driven roller 53. The low-heat-capacity linear heating element 54 is suspended between the three members 52, 53, 54 which are parallel to each other.

The fixing film 51 serves as a heated material carrying an unfixed toner image Ta conveyed from an image forming unit (not shown) on the upper surface at a predetermined peripheral speed in a clockwise direction accompanying the clockwise rotation of the driving roller 52. The recording material sheet P is driven to rotate at a peripheral speed substantially equal to the conveying speed (process speed) of the recording material sheet P.

Reference numeral 55 denotes a pressing roller as a pressing member, which presses the lower end of the endless belt-shaped fixing film 51 against the lower surface of the heating element 54 by pressing means (not shown). Yes, the recording material sheet P rotates counterclockwise in the forward direction in the transport direction.

The heating element 54 is a low-heat-capacity linear heating element whose longitudinal direction is the direction intersecting with the plane movement direction of the film 51 (the width direction of the film), and includes a heater substrate (base material) 56 and a current-generating heating resistor (heating element) 57. -Consists of a surface protective layer 58, a temperature sensor 59, etc.
It is fixed to and supported by a support 61 via a heat insulating material 60.

A recording material sheet P carrying an unfixed toner image Ta conveyed from an image forming unit (not shown) on the upper surface is guided by a guide 62 and is fixed to a fixing film 51 of a pressure contact portion N between a heating element 54 and a pressure roller 55. The non-fixed toner image enters the gap between the pressure roller 55 and the unfixed toner image surface is brought into close contact with the lower surface of the fixing film 51 which is rotationally driven in the same direction at the same speed as the conveyance speed of the recording material sheet P and is together with the film. It passes between the mutual press contact portions N between the heating element 54 and the pressure roller 55 in an overlapping state.

The heating element 54 is energized and heated at a predetermined timing, and the thermal energy of the heating element 54 is transmitted to the recording material sheet P in close contact with the film via the film 51, and a toner image is formed.
Ta is heated and becomes a softened / melted image Tb in the process of passing through the press-contact portion N.

The running direction of the rotatingly driven fixing film 51 is turned at a steep angle at the edge portion S of the heat insulating material 60 where the curvature is large. Accordingly, the recording material sheet P conveyed through the pressure contact portion N in a state where the recording material sheet P overlaps the fixing film 51 is moved to the edge portion S
In the above, the curvature is separated from the fixing film 51 and the paper is discharged. By the time the toner reaches the paper discharge section, the toner is sufficiently cooled and solidified, and is in a state of being completely fixed Tc on the recording material sheet P.

(Problems to be Solved by the Invention) Such a film heating system apparatus has the following problems as problems.

(1) In a system in which the film 51 is constantly tensioned over the entire circumference and the film is stretched and the film is transported, a large driving torque is required for the film transport driving. As a result, it is necessary to upgrade the rigidity and performance of the device components and the driving force transmitting means, etc., to ensure reliability, which contributes to the complexity, size, cost, etc. of the device configuration. .

(2) If the alignment such as the parallelism between the driving roller 52 and the driven roller 53 or the parallelism between the rollers and the heating element 54 is incorrect, the entire circumference of the member 52, 53, 54 is always required. A very large biasing force acts on one end or the other end in the film width direction along the length of the members 52, 53, and 54 on the film 51 which is tensioned and suspended.

100 μm or less, preferably 40 μm, for improving the quick start property by reducing the heat capacity as the film 51
Originally, a thin material having a low rigidity (low stiffness) is used, and the film 51 is stretched between a plurality of bridging members 52, 53, 54, so that the circumferential length of the film is long. As a result, even though the rigidity of the film 51 is low, such a film is subjected to a very large biasing force as described above to move and the film end on the shift side is shifted to the device member on the side. When you hit
The end of the film cannot withstand a large deviation force, resulting in damage such as buckling or breakage.

Further, depending on the position of the film 51, there may be a problem that the balance of the conveying force of the film is lost, the balance of the pressing force at the time of fixing is not uniform, and the balance of the temperature distribution of the heating element 54 is lost. .

The present invention also belongs to a film heating method using an endless heat-resistant film,
It is an object of the present invention to provide an image heating apparatus which can reduce a film shift force and solve the above-mentioned problems.

(Means for Solving the Problems) The present invention provides a heating element, an endless film that slides on the heating element, and a driving rotation that forms a nip with the heating element via the film and drives the film. Member, and a guide member for guiding a film provided inside the film, the film is loosely suspended with respect to the guide member, the guide member is at least the film In an image heating apparatus having a guide portion on the upstream side of the heating body with respect to a moving direction, and nipping and conveying a recording material carrying an image in the nip and heating the image, the film is driven by the guide portion when the film is driven. And a non-guide portion that does not guide the film between the guide portion and the nip. Thermal equipment.

(Operation) (1) In a state where the film is driven and the heating element generates heat, the film in the nip portion formed between the heating element and the pressure contact member (driving rotary member) with the film interposed therebetween and the pressure contact member. When the recording material supporting the developed image is introduced with the developed image carrying surface side in the film side, the recording material adheres to the outer surface of the film and moves through the nip together with the film, and in the process of moving and passing. In the nip portion, the thermal energy of the heating element in contact with the inner surface of the film is applied to the recording material via the film, and the recording material supporting the visible image is heated by a film heating method.

(2) The film shown in FIG. 13 is provided with a structure in which at least a part of the film has a tension-free portion (a state in which tension is not applied) at all times, that is, both when the film is not driven and when the film is driven. It is possible to greatly reduce the driving torque for film driving compared to the configuration (tension type) in which a film with a long perimeter is always tensioned and driven over the entire circumference, such as that of Becomes

Therefore, it is possible to simplify, reduce the size, reduce the cost, and the like of the device configuration and the drive system configuration, and to make the device components and assembly accuracy rough.

(3) Even if the film is shifted to one side or the other side in the film width direction in the process of driving the filter, the shift force is set to a tension corresponding to the entire circumference of the film as in the tension type apparatus of FIG. Is significantly smaller than the one with

Therefore, even if the film shifts and the film end on the shift side comes into contact with the device side member on that side, the film shift force is small, so the film rigidity (strength) against the shift force is small. Is sufficiently overcome to prevent damage to the edge of the film.

Therefore, it is possible to restrict the deviation movement of the film by a simple film end regulating member such as a flange seat (flange member), and a large film deviation movement including a film deviation detection means and a return movement means. There is no need for a control mechanism.
It is possible to reduce the size and cost.

In addition, since the film can be reduced in rigidity as much as the biasing force is reduced, it is possible to improve the quick start property of the apparatus by using a thinner film having a smaller heat capacity.

(4) When the film is not driven, almost the entire circumference of the film except for the portion sandwiched between the nip portion between the heating element and the pressure contact member is tension-free, and when the film is driven. (2) The tension is applied only to the portion between the nip portion and the film inner surface guide portion near the nip portion on the upstream side of the nip portion in the film moving direction and between the nip portion. ) ・
As described in the item (3), the film driving force is small and the film biasing force is also small. At the time of driving the film, at least the film partial surface near the recording material entry side of the nip portion and the film partial surface of the nip portion Is prevented by the action of the tension.

Thereby, the recording material introduced into the nip portion always moves and passes through the nip portion together with the film in close contact with the film surface without wrinkles. Therefore, the occurrence of uneven heating and fixing due to the situation in which the material to be heated adheres to the wrinkled film surface or the occurrence of the situation where the wrinkled film passes through the nip portion, generation of folding lines on the film surface, and the like are prevented. You.

(5) A rotating member that is rotated by a drive source while being pressed against a heating body with the film interposed therebetween, and that drives the film to move at a predetermined speed in the recording material conveying direction while sliding the inner surface of the film against the heating body surface. A roller body or an endless belt body having both functions of pressing and driving the film), it is possible to reduce the biasing force applied to the film and to drive the position of the rotating body and the rotating body. Gear position accuracy can be improved, the device configuration can be simplified, and an inexpensive and highly reliable device can be obtained.
Further, the entire circumference of the endless film used can be reduced.

(Embodiment) The drawings show an apparatus according to an embodiment of the present invention (image heating fixing device 10).
0).

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

Reference numeral 1 denotes a horizontally long apparatus frame (bottom plate) having an upward channel (groove) in cross section made of sheet metal;
The left side wall plate and the right side wall plate integrally provided with the frame 1 at both left and right end portions thereof are upper covers of the apparatus, and are fitted between the upper end portions of the left and right side wall plates 2 and 3 so that the left and right end portions are formed. The left and right side wall plates 2 and 3 are fixed with screws 5 respectively. It can be removed by loosening the screw 5.

Reference numerals 6 and 7 denote longitudinally-notched elongated holes formed symmetrically in the substantially central surfaces of the left and right side wall plates 2 and 3, and 8 and 9 denote respective elongated holes 6.
7 is a pair of left and right bearing members fitted and engaged with the lower end of the bearing 7.

Reference numeral 10 denotes a film pressing roller (pressing roller, backup roller) serving as a rotating body (drive rotating member) that forms a nip portion with a film interposed between the heating body and a heating body, which will be described later. And a roller portion 12 made of a rubber elastic material having good releasability, such as silicone rubber, provided on the shaft. The left and right ends of the central shaft 11 are rotatably mounted on the left and right bearing members 8 and 9 respectively. It is supported.

Reference numeral 13 denotes a horizontally long stay made of sheet metal, and an inner surface guide member of a film 21 described later, a heating body 19 and a heat insulating member described later.
Also serves as 20 supporting and reinforcing members.

The stay 13 has a horizontally long flat bottom portion 14 and this bottom portion.
A front wall plate 15 and a rear wall plate 16 having a cross section outwardly curved arc provided by being sequentially raised from both longitudinal sides of 14 respectively, and a pair of right and left protruding outward from both right and left ends of the bottom portion 14 respectively. It has horizontal overhang lugs 17 and 18.

Reference numeral 19 denotes a horizontally long low-heat-capacity linear heating element having a structure to be described later (FIG. 6), which is attached to and supported by a horizontally long heat-insulating member 20. 13 is attached to and supported by the lower surface of the horizontally long bottom surface portion 14 in parallel.

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

22 and 23 are formed by externally fitting the film 21 to the stay 13 including the heating element 19 and the heat insulating member 20 and then fitting and supporting the horizontally protruding lugs 17 and 18 at the left and right ends of the stay 13 It is a pair of film end regulating flange members. As will be described later, the distance G (FIG. 8) between the inner surfaces 22a and 23a of the flange seats of the pair of left and right flange members 22 and 23 is
Is set slightly larger than the width dimension C (the same).

Reference numerals 24 and 25 denote horizontal overhang lugs protruding outward from the outer surfaces of the pair of left and right flange members 22 and 23, and the outward horizontal overhang lugs 17 and 18 on the stay 13 side are respectively provided by the flange members 22 and 23.・ 23 horizontal overhang lugs 24 ・ 25
It is fully fitted in the insertion hole provided in the wall thickness of the first member, and firmly supports the left and right flange members 22 and 23.

The assembling of the apparatus is carried out by removing the upper cover 4 from the space between the left and right side walls 2 and 3 and setting the left and right bearing members 8 and 9 on the left and right end portions of the shaft 11 in advance. The left and right bearing members 8 and 9 are fitted into the longitudinal notches 6 and 7 of the left and right side wall plates 2.3 and 3 from the upper end open portions, and the pressure roller 10 is inserted between the left and right side wall plates 2 and 3. The bearing members 8 and 9 are lowered to a position where they can be received by the lower ends of the elongated holes 6 and 7 (drop-down type).

Next, a stay 13, a heating body 19, a heat insulating member 20, a film
21, an intermediate assembly in which the left and right flange members 22 and 23 are pre-assembled in the relationship shown in the figure, with the heating body 19 side facing downward, and the left and right outwardly projecting ends of the heat insulating member 20 and the left and right flange members 22. The 23 horizontal overhang lugs 24 and 25 are fitted into the longitudinal cutout slots 6 and 7 of the left and right side wall plates 2.3 and 3 from the upper end open portions, and are inserted between the left and right side wall plates 2 and 3 to face downward. The heating body 19 is lowered until it is received by hitting the upper surface of the pressure roller 10 previously incorporated with the film 21 interposed therebetween (drop-down type).

The lugs 24 of the left and right flange members 22 and 23 protrude outside the left and right side wall plates 2 and 3 through the elongated holes 6 and 7.
・ Coil springs 26 and 27 are positioned vertically on support lugs provided on the upper surface of the lug, and set vertically, and upper cover 4 is provided on the left and right end sides of upper cover 4. Each of the coil springs 26, 27 is attached to the lug 24, with the overhang lugs 28, 29 corresponding to the upper ends of the set coil springs 26, 27, respectively.
While being compressed between 28, 25, and 29, they are fitted to a predetermined position between the upper end portions of the left and right side wall plates 2, 3 and fixed between the left and right side wall plates 2, 3 with screws 5.

As a result, the stay 13, the heating element 19, the heat insulating member 20, the film 21, and the entire left and right flange members 22 and 23 are pressed downward by the reaction force of the coil springs 26 and 27, and the heating element 19 is pressed.
The pressure roller 10 and the pressure roller 10 are held in a state in which they are pressed almost uniformly across the film 21 with a contact pressure of, for example, a total pressure of 4 to 7 kg.

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

Reference numeral 32 denotes a heated material entrance guide which is mounted on the front wall of the apparatus frame 1 and supports a visible image (powder toner image) Ta as a heated material introduced into the apparatus. 7) is guided between the film 21 and the pressure roller 10 in the nip portion (heat fixing portion) N between the heating body 19 and the pressure roller 10 which are pressed against each other with the film 21 interposed therebetween.

Reference numeral 33 denotes a heated material exit guide (separation guide) attached to the rear wall of the apparatus frame 1 for discharging the recording sheet passing through the nip portion to a lower discharge roller 34 and an upper pinch roller 38. To the nip.

The discharge roller 34 is rotatably supported at both left and right ends of a shaft 35 between bearings 36 and 37 provided on the left and right side walls 2 and 3. The pinch roller 38 has its shaft 39 received by a hook 40 formed by bending a part of the rear wall of the upper cover 4 inward, and is brought into contact with the upper surface of the discharge roller 34 by its own weight and a pressing spring 41. The pinch roller 38 is driven to rotate by the rotation of the discharge roller 34.

G1 is a first gear fixed to the right end of the roller shaft 11 projecting outward from the right side wall plate 3, and G3 is similarly a first gear fixed to the right end of the discharge roller shaft 35 projecting outward from the right side wall plate 3. 3
The gear G2 is a second gear as a relay gear provided by being pivotally attached to the outer surface of the right side wall plate 3. The first gear G1 and the third gear G2 are provided.
Meshing with G3.

The first gear G1 receives a driving force from a driving gear G0 of a driving source mechanism (not shown), and the pressing roller 10 is driven to rotate counterclockwise in FIG. 1, and in conjunction therewith, the rotating force of the first gear G1 is reduced. The output roller 34 transmitted to the third gear G3 via the second gear G2 is also the first gear G3.
It is driven to rotate counterclockwise in the figure.

(2) Operation When the endless heat-resistant film 21 is not driven, the heating element 19 and the pressure roller as shown in FIG.
Except for the portion sandwiched between the nip portion N and the portion 10, almost the entire circumference of the remaining portion is tension-free.

When the drive is transmitted from the drive gear G0 of the drive source mechanism to the first gear G1 and the pressure roller 10 is driven to rotate in the counterclockwise direction in FIG.
Feed force is applied by the frictional force with the rotating pressure roller 10,
The endless heat-resistant film 21 is rotationally driven in the clockwise direction A while the inner surface of the film slides on the surface of the heating body 19 at substantially the same rotational speed as the rotational speed of the pressure roller 10.

In the driving state of the film 21, the pulling force f acts on the film portion upstream of the nip portion N in the film rotation direction, so that the film 21 is more than the nip portion N as shown by the solid line in FIG. Contacting the film inner surface guide portion near the nip portion on the upstream side in the film rotation direction, that is, the substantially lower half surface portion of the outwardly curved arc front plate 15 as the film inner surface guide of the stay 13 on which the film 21 is fitted. Then, it rotates while sliding.

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

In particular, since there is a non-guide portion that does not guide the film 21 between the front plate 15 and the nip portion N, the film 21 subjected to tension by the front plate 15 can be stretched without any obstacle by the non-guide portion. The wrinkles of the film 21 can be more reliably prevented before entering the nip portion N.

Then, in the state where the above-described film drive and the energization of the heating element 19 are performed, the recording material sheet P carrying the unfixed toner image Ta as the material to be heated is guided by the entrance guide 32.
When the recording material sheet P is introduced between the rotating film 21 of the nip portion N and the pressure roller 10 in an upward direction, the recording material sheet P comes into close contact with the surface of the film 21 and moves along the nip portion N together with the film 21. The heat energy of the heating element 19 that is in contact with the inner surface of the film at the nip portion N is applied to the recording material sheet P via the film in the process of moving and passing the toner image.
Ta becomes a softened and fused image Tb.

The recording material sheet P that has passed through the nip N is separated from the surface of the film 21 with the toner temperature higher than the glass transition point, guided by the exit guide 33 between the discharge roller 34 and the pinch roller 38, and sent out of the apparatus. . The softened / fused toner image Tb is cooled and solidified while the recording material sheet P exits the nip portion N and leaves the film 21 to reach the discharge roller 34.
Tc and fix.

Recording material sheet P introduced into nip N in the above
As described above, the tension acts on the film portion surface without wrinkles, and the nip portion N moves together with the film 21 in close contact with the film portion 21. Therefore, a situation in which the wrinkled film passes through the nip portion N may occur. This causes no uneven heating and uneven fixing, and no breakage of the film surface.

The film 21 has a part N of its entire circumference both when driven and when driven.
Alternatively, since tension is applied only to BN, that is, when the film 21 is not driven (FIG. 6), the film 21 is substantially free of tension over the entire remaining portion except for the nip portion N. The tension acts only on the nip portion N and the film portion B near the recording material sheet entry side of the nip portion N, and almost the entire remaining circumferential portion is tension-free. Since a short film can be used, the driving torque required for driving the film is small, and the film device configuration, components, and drive system configuration are simplified, downsized, and reduced in cost.

When the film 21 is not driven (FIG. 6), it is also driven (FIG. 7).
As shown in the figure, since tension is applied only to a part N or BN of the entire circumferential length of the film 21 as described above, the film 21 is driven on one side Q (second
(See FIG. 2), or even if a shift to the other side R occurs, the shift force is small.

Therefore, the film 21 is shifted Q or R, and the left edge of the film 21 is pressed against the flange seat inner surface 22a as the film end regulating surface of the left flange member 22, or the right edge is pressed against the flange seat inner surface 23a of the right flange member 23. However, since the film deviating force is small, the rigidity of the film sufficiently overcomes the deviating force, and no damage such as buckling or breakage of the film end occurs. Since the simple means for regulating the film deviation is only required by the flange members 22 and 23 as in the apparatus of this embodiment, the apparatus configuration can be simplified, miniaturized and reduced in cost in this respect as well, and the inexpensive and highly reliable apparatus can be used. Can be configured.

As the film deviation regulating means, in addition to the flange members 22 and 23 in the case of the apparatus of the present embodiment, for example, a rib made of a heat-resistant resin is provided at the end of the film 21 in the circumferential direction of the endless film, and the rib is regulated. Is also good.

Further, as the film 21 to be used, the rigidity can be reduced as much as the biasing force is reduced as described above, so that a thinner film having a smaller heat capacity can be used to improve the quick start property of the apparatus.

(3) Film 21

The film 21 has a total thickness of 100 μm in order to reduce the heat capacity and improve the quick start property.
m, preferably 40 μm or less, heat resistance of 20 μm or more.
A single layer or composite layer film having releasability, strength, durability and the like can be used.

For example, polyimide / polyetherimide (PEI)
Polyethersulfone (PES) / tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PF
A)-Polyetheretherketone (PEEK)-Polyparabanic acid (PPA), or PTFE on at least the image contacting surface side of a composite film such as a 20 µm thick polyimide film
(Tetrafluoroethylene resin), fluororesin such as PAF, FEP, etc.
Silicone resin, etc., and a 10 μm thick release coating layer to which conductive materials (carbon black, graphite, conductive whiskers, etc.) are added.

(4) Heating body 19 and heat insulating member 20.

The heating element 19 includes a heater substrate 19a (see FIG. 6), a current-generating heating resistor (heating element) 19b, a surface protection layer 19c, a temperature measuring element 19d, and the like, similarly to the heating element 54 of the apparatus shown in FIG.

The heater substrate 19a is a member having heat resistance, insulation, low heat capacity and high thermal conductivity, for example, a thickness of 1 mm, a width of 10 mm, and a length of 240 mm.
mm alumina substrate.

The heating element 19b is made of an electric resistance material such as Ag / Pd (silver palladium), Ta ₂ N, or RuO ₂ along the length substantially at the center of the lower surface of the heater substrate 19a (facing the filter 21). About 10
It is coated by a screen printing or the like in a linear or narrow band having a width of 1 to 3 mm with a thickness of 1 to 3 mm, and a heat-resistant glass is coated thereon as a surface protective layer 19c by about 10 μm.

The temperature measuring element 19d is, for example, a low-heat-capacity temperature measuring resistor such as a Pt film provided by applying a screen printing or the like to a substantially central portion of the upper surface of the heater substrate 19a (the side opposite to the surface on which the heating element 19b is provided). Body. A thermistor with a low heat capacity can also be used.

In the case of the heating element 19 of the present example, the heating element 19b having a linear or narrow band shape is energized at a predetermined timing by an image forming start signal to cause the heating element 19b to generate heat over substantially the entire length.

The energization is 100 V AC, and the supplied electric power is controlled by controlling the phase angle to be energized by an energization control circuit (not shown) including a triac according to the temperature detected by the temperature detecting element 19c.

The heating element 19 has a small heat capacity of the heater substrate 19a, the heating element 19b, and the surface protection layer 19c due to the current supply to the heating element 19b, so that the temperature of the heating element surface rapidly rises to a required fixing temperature (for example, 140 to 200 ° C.). I do.

The heat capacity of the heat-resistant film 21 in contact with the heating element 19 is also small, and the heat energy of the heating element 19 is
The heat transfer is effectively transmitted to the recording material sheet P side in pressure contact with the film through the film, and the image is heated and fixed.

As described above, the surface temperature of the film facing the heating element 19 rises to a sufficiently high temperature relative to the melting point of the toner (or the temperature at which the toner can be fixed to the recording material sheet P) in a short time, so that quick start performance is excellent. In addition, there is no need to raise the temperature of the heating element 19 in advance, that is, so-called standby temperature control, so that energy can be saved and the temperature inside the apparatus can be prevented.

The heat insulating member 20 insulates the heating element 19 to use heat effectively, and has heat insulating property and high heat resistance, for example, PP
High heat resistant resin such as S (polyphenylene sulfide), PAI (polyamide imide), PI (polyimide), PEEK (polyetheretherketone), liquid crystal polymer, etc.

(5) About film width C and nip length D.

As shown in the dimensional relationship diagram of FIG. 8, the width of the film 21 is C, and the length of the nip formed by pressing the heating member 19 and the pressing roller 10 as a rotating member is D with the film 21 interposed therebetween.
In this case, it is preferable to set a relational configuration of C <D.

That is, when the film 21 is conveyed by the roller 10 in the configuration of C ≧ D, the film conveyance force (pressing force) received by the film portion in the nip length D region and the nip length D out of the nip length D region are reversed. The film transport force received by the film portion of the former is that the inner surface of the former film portion is slid and transported in contact with the surface of the heating body 19, whereas the inner surface of the latter film portion is the material of the surface of the heating body 19 Because it is slid and conveyed in contact with the surface of the heat insulating member 20 of different
There is a possibility that the film 21 may be damaged at the both ends in the width direction, such as wrinkles or breakage during the film transport process.

On the other hand, by setting the relationship of C <D, the inner surface of the entire length region C in the width direction of the film 21 comes into contact with the surface within the length range D of the heating member 19 and slides on the surface of the heating member. Since the film is conveyed, the film conveying force becomes uniform in the entire length region C in the film width direction, so that the above-described trouble of the film end portion damage is avoided.

Further, since the pressure roller 10 used in this embodiment as a rotating body is made of a rubber material having excellent elasticity such as silicon 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 coefficient of friction between the roller 10 and the film 21 at a portion corresponding to the length range E of the heating element 19b and the heating element 19b
The coefficient of friction between the roller 10 and the film 21 in a portion corresponding to the outside of the length range E of the roller 10 is different.

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

As a result, the film 21 can be driven stably by the roller 10, and damage to the edge of the film can be prevented.

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

(6) Pressure roller 10

The nip portion N is formed between the heating member 19 and the film 21. The pressure roller 10 as a rotating member for driving the film is made of, for example, a rubber elastic material having good releasability such as silicon rubber. The shape is an inverted crown shape as shown in an exaggerated model diagram of FIG. 9A or 9B, or an end portion of the inverted crown in an inverted crown shape, in comparison with a straight shape in the longitudinal direction. A substantially inverted crown shape obtained by cutting 12a is preferable.

The effective length H of the roller 10 is, for example, the degree d of the inverted crown.
In the case of 230 mm, it is preferable to set d = 100 to 200 μm.

That is, in the case of a straight-shaped roller, the pressure distribution in the film width direction applied to the film 21 by the roller at the nip portion N with the heating element 19 due to variations in component accuracy or the like is closer to the central portion than to the edge in the width direction of the film. Was sometimes higher. In other words, the transporting force of the film by the rollers is greater at the center than at the ends in the width direction of the film, and a force acts on the film 21 such that the film portion having a smaller transporting force is directed toward the film portion having the greater transporting force. Therefore, the film portion on the side of the film edge may approach the center portion of the film and cause wrinkles in the film. Further, when the recording material sheet P is introduced into the nip portion N, the recording material sheet P In some cases, wrinkles may be generated during the transport passage.

On the other hand, by forming the pressure roller 10 in the shape of an inverted crown, the pressure distribution in the film width direction applied to the film 21 by the roller at the nip portion N with the heating element 19 is opposite to the above case. The widthwise end is larger than the center, whereby a force is applied to the film 21 from the center toward both ends, that is, the film 21 is conveyed while undergoing a wrinkle elongation action, and the film wrinkles are reduced. It is possible to prevent wrinkles from occurring on the introduced recording material sheet P while preventing the occurrence of wrinkles.

The pressurizing roller 10 as a rotating body presses the film 21 against the heating body 19 with the film 21 interposed therebetween with the heating body 19 as in the apparatus of the present embodiment, and drives and moves the film 21 to a predetermined speed, When a recording material sheet P as a material to be heated is introduced between the recording material sheet 21 and the recording material sheet 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 at a predetermined speed together with the film 21. As a member, the biasing force applied to the film can be reduced, and the position of the pressure roller 10 and the position accuracy of the gear for driving the roller can be improved.

That is, the pressurizing function for pressurizing the film 21 or the film 21 and the recording material sheet P against the heating body 19 and the driving function for moving and driving the film 21 are separately provided by a pressurizing function rotating body (necessary (The pressing force is obtained by pressurizing the rotating body) and the film driving function rotating body is used. If the alignment between the heating body 19 and the film driving function rotating body is out of order, the thin film is formed. A large biasing force acts on the film 21 in the width direction, and the end of the film 21 may be damaged or broken.

A heating element is added to the pressure rotating body that also serves as the film driving member.
When the pressing force required for the pressure contact with 19 is applied 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 are difficult.

On the other hand, as described above, the recording material sheet P is brought into pressure contact with the heating member 19 via the film 21 by applying a pressing force required for fixing to the heating member 19 by the pressing roller 10 serving as a rotating member. The above-mentioned effects can be obtained by simultaneously performing the above driving, and the configuration of the device is simplified, so that an inexpensive and highly reliable device can be obtained.

Note that, instead of the roller 10, the rotating body may be an endless belt 10A that is driven to rotate as shown in FIG.

(7) Recording material sheet discharge speed.

The conveying speed of the recording material sheet P introduced into the nip portion N as the material to be heated by the pressing roller 10 (rotary body), that is, the peripheral speed of the roller 10 is V10, and the recording material sheet discharging and conveying speed of the discharging roller 34 That is, the peripheral speed of the discharge roller 34 is V34
, It is preferable to set the speed relationship of V10> V34.
The speed difference may be set at several%, for example, about 1 to 3%.

When the maximum width dimension of the recording material sheet P that can be introduced into the apparatus and used is F (see FIG. 8), V10 ≦ V34 under the condition of F <C in relation to the width dimension C of the film 21. In such a case, the sheet portion of the recording material sheet P which is being conveyed across both the nip portion N and the discharge roller 34 is pulled by the discharge roller 34 while passing through the nip portion N.

At this time, the film 21 whose surface is coated with PTFE or the like having good releasability is conveyed at the same speed as the pressure roller 10. On the other hand, the recording material sheet P is conveyed at a speed higher than the peripheral speed of the pressure roller 10 because a pulling conveyance force by the discharge roller 34 is applied in addition to the conveyance force by the roller 10. That is, in the nip portion N, the recording material sheet P and the film 21 slip, so that the unfixed toner image Ta (the seventh image) on the recording material sheet P while the recording material sheet P passes through the nip portion N is generated. There is a possibility that the toner image Tb in the softened / melted state may be disturbed.

Therefore, as described above, by setting the peripheral speed V10 of the pressure roller 10 and the peripheral speed V34 of the discharge roller 34 in a relationship of V10> V34, the recording material sheet P and the film 21
Since the pulling force of the discharge roller 34 does not act on the sheet P and only the conveying force of the pressure roller 10 is applied to the sheet P, it is possible to prevent the occurrence of the above-described image disorder based on the slip between the sheet P and the film 21. Can be.

In this embodiment, the discharge roller 34 is provided on the image heating apparatus 100 side, but may be provided on the main body side such as an image forming apparatus in which the image heating apparatus 100 is incorporated.

(8) Regarding the film end regulating flange interval.

A pair of left and right flanges as film edge regulating means
Inner surface 22a / 23a of flange seat as film end regulating surface of 22/23
Assuming that the distance between the gaps is G (FIG. 8), the relationship with the width C of the film 21 is preferably set to C <G. For example, when C is set to 230 mm, G is set to be larger by about 1 to 3 mm.

That is, the film 21 is, for example, 200 ° C. in the nip portion N.
The dimension C increases due to expansion due to the heat of the nearby heating element 19.
Therefore, if the width C and the distance G between the flanges of the film 21 at normal temperature are set to C = G and both ends of the film 21 are regulated by the flange members 22 and 23, the above-mentioned thermal expansion of the film during the operation of the apparatus. Produces a state of C> G. Since the film 21 is, for example, a thin film having a thickness of about 50 μm, in the state of C> G, the contact pressure (end pressure) of the flange members 22 and 23 against the film end regulating surfaces 22 a and 23 a increases. The end breaks without being able to endure it
In addition to being damaged by buckling and the like, the end of the film 21 and the flange member 22
The frictional force between the film end regulating surfaces 22a and 23a of the film 23 also increases, so that the film conveying force is reduced.

By setting the dimensional relationship of C <G, even if the film 21 expands due to heating, the gap (G−
C) is provided between both ends of the film 21 and the film end regulating surfaces 22a and 23a of the flange member so that both ends of the film 21 are simultaneously formed on the film end regulating surfaces 22a and 2a of the flange member.
No contact with 3a.

Therefore, even if the film 21 thermally expands, the end contact pressure of the film 21 does not increase, so that the end of the film 21 can be prevented from being damaged, and the driving force of the film 21 can be reduced.

(9) Relationship of friction coefficient between each member.

a. The friction coefficient of the surface of the roller (rotary body) 10 against the outer peripheral surface of the film 21 is μ1, b. The friction coefficient of the surface of the heater 19 against the inner peripheral surface of the film 21 is μ2, c. Coefficient of friction μ
3. d. The coefficient of friction of the outer peripheral surface of the film 21 against the surface of the recording material sheet P as the material to be heated is μ4, e. The friction coefficient of the surface of the roller 10 against the surface of the recording material sheet P is μ5, and f. The maximum length dimension of the recording material sheet P in the transport direction is 1, g. When the apparatus is incorporated in a transfer type image forming apparatus as an image heating and fixing apparatus, the image transfer means unit transfers the image from the image transfer unit to the image heating and fixing apparatus. The transport path length of the recording material sheet (transfer material) P up to the nip portion N is l2.

 Thus, the relationship between μ1 and μ2 has a relationship of μ1> μ2.

That is, in this type of film heating system, the μ4
Is set to μ4 <μ5, and in the image forming apparatus, the relationship between 1 and l2 is 1> l2.

At this time, when μ1 ≦ μ2, the film 21 and the recording material sheet P slip in the cross-sectional direction of the heat fixing means (the conveyance speed of the film 21 is delayed with respect to the peripheral speed of the roller 10), and the recording material sheet Is disturbed.

Further, the recording material sheet P and the film 21 slip together (the film 21 and the recording material sheet P with respect to the peripheral speed of the roller 10).
In the case of a transfer type image forming apparatus, when the toner image is transferred onto the recording material sheet (transfer material) in the image transfer unit, the toner image on the recording material is also transferred. It will be disturbed.

By setting μ1> μ2 as described above, it is possible to prevent the film 21 and the recording material sheet P from slipping on the roller 10 in the cross-sectional direction.

Further, regarding the width dimension C of the film 21, the length dimension H of the roller 10 as a rotating body, and the length dimension D of the heating body 19,
Under the conditions of C <H and C <D, the relational configuration of μ1> μ3 is established.

That is, in the relationship of μ1 ≦ μ3, the film 21 and the roller 10 slip in the width direction of the heat fixing unit, 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 the heat fixing. Will be done.

With the relation of μ1> μ3 as described above, it is possible to prevent the film 21 from slipping with respect to the roller 10 in the width direction, particularly, outside the recording material sheet P.

By setting μ1> μ2 and μ1> μ3 in this manner, the transport speed of the film 21 and the recording material sheet P can always be made equal to the peripheral speed of the roller 10, and image disturbance during fixing or transfer can be prevented. Μ1> μ
2. By simultaneously executing μ1> μ3, the roller 10
And the transport speed of the film 21 and the recording material sheet P can always be the same, and a stable fixed image can be obtained in the transfer type image forming apparatus.

(10) About the film shift control.

In the apparatus for controlling the film shift of the embodiment shown in FIGS. 1 to 10, a pair of left and right flange members 22 and 23 for regulating the film end is disposed at both ends in the width direction with the film 21 as the center.
The following configuration is also effective as a film one-side end regulation type, in which the shift movement QR in both the left and right directions is dealt with.

That is, the drive direction of the left and right pressure coil springs 26 and 27 as shown in the apparatus of FIG. Spring
By setting the pressing force f27 of the film 27 to be higher than the pressing force f26 of the spring 26 on the non-drive side (f27> f26), the film 21
To control the film transport force by always moving to the right side R, which is the driving side, and by changing the shape of the heating element 19 and the shape of the roller 10 between the driving end side and the non-driving end side. The direction of the shift of the film is always in one direction, and the end of the film on the shift side is a flange member as a regulating member for the end of the film on that side, or a means such as a film rib and an engagement guide member. Regulation, that is,
In the apparatus shown in FIG. 11, by restricting only the end portion on the side R of the film 21 by the restricting member 27, the film can be controlled stably and easily. Thereby, when the apparatus is an image heating and fixing apparatus, a stable and good fixed image can be always obtained.

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

The same effect can be obtained even in the case of a tension type device configuration in which the film is tensioned and driven around the entire circumference, or in the case of a tension free type device configuration as in the present embodiment. Although possible, the arrangement is particularly suitable for tension-free types.

(11) Example of Image Forming Apparatus FIG. 12 shows a schematic configuration of an example of an image forming apparatus incorporating the image heating / fixing apparatus 100 of FIGS.

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

Reference numeral 60 denotes a process cartridge, which includes four process devices of a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a drum) 61, a charger 62, a developing device 63, and a cleaning device 64. The process cartridge is detachably attached to and removed from a predetermined position in the apparatus by opening the opening / closing section 65 of the apparatus and opening the inside of the apparatus.

The drum 61 is rotated in the clockwise direction indicated by the arrow in response to the image formation start signal, and the surface of the rotating drum 61 is uniformly charged to a predetermined polarity and potential by the charger 62. The main scanning exposure with the laser beam 67 modulated according to the time-series electric digital pixel signal of the target image information output from the target image information is performed on the surface of the drum 61 by the electrostatic force corresponding to the target image information. Latent images are sequentially formed. The latent image is then developed 63
Is visualized as a toner image.

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

The recording material sheet P that has passed through the transfer unit 73 is separated from the surface of the drum 61 and introduced into the fixing device 100 by the guide 74, and the unfixed toner image is heated and fixed by the operation and operation of the device 100 described above. The image is output from the outlet 75 as an image formed product (print).

Drum from which recording material sheet P is separated through transfer unit 73
The surface 61 is repeatedly used for image formation after the removal of contaminants such as transfer residual toner by a cleaning device 64.

The image heating apparatus of the present invention can be effectively used not only as the image heat fixing apparatus of the image forming apparatus of the above-described example but also as an image surface heating polisher, a hypothetical wearing apparatus, and the like.

(Effect of the Invention) As described above, since the film heating type image heating apparatus of the present invention has a tension-free type configuration for the film, it is possible to reduce the driving force of the film and to shift the film. The force can be reduced to prevent damage to the edge of the film, and the equipment parts and assembly accuracy can be roughened.
A device that can be reduced in cost and that is stable and reliable.

Driving the film by the pressurizing rotating body (driving rotating member) further simplifies the configuration of the apparatus and reduces costs.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an apparatus according to one embodiment. FIG. 2 is a longitudinal sectional view. FIG. 3 is a right side view. FIG. 4 is a left side view. FIG. 5 is an exploded perspective view of a main part. FIG. 6 is an enlarged cross-sectional view of a waist showing a film state when not driven. FIG. 7 is the same as above during driving. FIG. 8 is a dimensional relation diagram of constituent members. 9 (A) and 9 (B) are exaggerated shapes showing examples of the shape of the roller 10 as a rotating body. FIG. 10 is a diagram showing an example in which a rotating belt is used as a rotating body. FIG. 11 is a longitudinal sectional view of an example of an apparatus of a film one side end regulating type. FIG. 12 is a schematic configuration diagram of an example of an image forming apparatus. FIG. 13 is a schematic configuration diagram of a known example of a film heating type image heating fixing device. 19 is a heating element, 21 is an endless film, 13 is a stay, 10
Is a roller as a rotating body.

Claims (1)

(57) [Claims] 1. A heating element, an endless film that slides on the heating element, a driving rotating member that forms a nip with the heating element via the film and drives the film, and is provided inside the film. A guide member for guiding the film, wherein the film is loosely suspended with respect to the guide member, and the guide member is at least upstream of the heating body with respect to a moving direction of the film. An image heating apparatus that has a guide portion, and heats an image by nipping and conveying a recording material carrying an image in the nip, wherein when the film is driven, the film acts on the guide portion and the nip in tension. An image heating apparatus having a non-guide portion that does not guide the film between the guide portion and the nip.