JPH0527631A - Heating device - Google Patents

Abstract

PURPOSE:To suppress the occurrence of the unstabilization, etc., of the travelling properties of a film caused by the lowering of the temp. of the paper nonpassing part of a heating body, in a film heating system heating device adopting branching energizing structure on the electrically heating element of a heating body. CONSTITUTION:This heating device imparts heat energy to a material to be heated from the heating body 12 via the film 9 in such a manner that the film 9 is brought into contact with the heating body 12 to move and drive, the member to be heated 16 is adhered to the surface opposite to the heating body side, of the film and the position of the heating body is moved together with the film; the heating body 12 has an energizing heating layer 14 whose longitudinal direction crosses with a direction where the member to be heated 16 is moved to pass, and which is energized from both end parts, and branching cable runs 14b, 14e, and 14c branching from, at least, one prescribed position of the half-way part along the longitudinal direction of the electrically heating layer, and selectively energize-controlled, and a resistance value for the unit length of the branching cable run is different from that of the electrically heating layer, as a characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device of a system (film heating system) for applying heat energy to a material to be heated through a film.

More specifically, the film is brought into contact with the heating body and driven to move, the material to be heated is brought into close contact with the surface of the film opposite to the heating body side, and the film is moved and passed through the heating body position together with the film. The present invention relates to a heating device of a type that applies heat energy to a material to be heated through a film.

This apparatus is suitable for electrophotography, electrostatic recording, magnetic recording, etc. in image forming apparatuses such as copiers, laser beam printers, facsimiles, microfilm reader printers, image display (display) devices and recorders. Recording material (electrofax sheet, electrostatic recording sheet, transfer material sheet, printing paper, etc.) using toner made of heat-meltable resin by image forming process means
Image (unfixed toner image) corresponding to the target image information formed on the surface of the paper by direct method or indirect (transfer) method
Can be utilized as an image fixing device for performing heat fixing processing as a permanently fixed image on the surface of a recording material carrying the image.

Further, it can be used, for example, as a device for heating a material to be heated carrying an image so as to modify the surface properties of gloss and the like, and a device for post-treatment.

[0005]

BACKGROUND OF THE INVENTION With respect to a film heating type heating device of this type, the applicant has a heating body having an electric heating layer whose length is in a direction intersecting with a moving and passing direction of a material to be heated and which is energized from both ends. A structure having a branch electric path branched from at least one predetermined position in the middle of the energization heat generating layer and selectively energized is first proposed (Japanese Patent Application No. 1-282574). No.)

That is, the effective total length area between one end and the other end in the longitudinal direction of the energization heat generating layer corresponds to the width of the largest size heated material (hereinafter referred to as recording material) that can be supplied to the apparatus and used. And the length dimension. Further, a branch electric path is provided at an intermediate position in the effective full-length area of the electric heating layer, which corresponds to the position of the boundary between the paper passing portion and the non-paper passing portion of the heating element when a certain small-sized recording material is supplied.

[0007]. During the image fixing process by supplying the maximum size recording material, the free end side of the branch electric circuit is controlled to be in an open state, and a predetermined voltage is applied between one end and the other end of the energization heat generating layer to energize it. By energizing the heat generating layer, each part of the effective heat generating layer generates heat with a predetermined heat generation amount per unit length, and the image fixing process for the maximum size recording material is executed without any trouble.

[0008] During the image fixing process by supplying a small-sized recording material, when a voltage is applied to one end of the energizing heat generating layer and the other end and the free end of the branch electric circuit to energize the energizing heat generating layer, the paper is passed. The portion of the energizing heat generating layer corresponding to the section (the section from one end of the energizing heat generating layer to the branch point of the branch electric path) generates heat with a predetermined heat generation amount per unit length, and image fixing processing is performed on a small-sized recording material. Is executed.

In this case, the energizing heat generating layer portion (the section from the branch point of the branching electric path to the other end of the energizing heating layer) corresponding to the non-sheet passing portion is a conducting circuit in which the energizing heating layer portion and the branching electric path are in parallel. And the current is shunted to both.

As a result, the heat generation amount per unit length of individual and sum of the current-carrying heat generating layer portion and the branch electric circuit portion corresponding to the non-paper passing portion is lower than that of the current passing heat generating layer portion of the paper passing portion. . Therefore, the excessive temperature rise of the non-sheet passing portion of the heating element is suppressed,
Inconvenience such as illegal running of the film due to excessive temperature rise is eliminated.

As described above, a plurality of branch electric circuits corresponding to the widths of recording materials of various sizes smaller than the maximum size recording material are provided at required positions in the middle of the energization heat generating layer, and the size width of the supplied recording material is increased. According to the above, by selectively energizing the corresponding branch electric circuits, it is possible to suppress the excessive temperature rise of the non-sheet passing portion of the heating body for recording materials of various sizes.

[0012]

However, in the case of the above-mentioned heating body structure capable of branching energization, when conducting branching energization corresponding to the size of the paper (recording material) used during fixing, the energization heat generating layer of the paper passing portion In comparison with the heat generation amount per unit length of the heating element, the heating layer in the non-paper-passing part tends to be too small, and the temperature distribution in the effective length area of the heating element is extremely different between the paper-passing part and the non-paper-passing part. Will end up. That is, contrary to the above-mentioned "non-sheet passing portion excessive temperature rise" phenomenon, a "non-sheet passing portion temperature drop" phenomenon in which the temperature of the non-sheet passing portion is too low with respect to the temperature of the sheet passing portion of the heating element It has been found that, due to this, the runnability of the film is destabilized (deviation of the film, wrinkles, etc.).

Therefore, the present invention relates to a film heating type heating device in which the current-carrying heat generating layer of the heating element has a branched current-flowing structure as described above, and the running property of the film due to the temperature decrease phenomenon of the non-sheet passing portion of the heating element. The purpose is to suppress the occurrence of destabilization.

[0014]

The present invention is a heating device characterized by the following constitutions.

(1) The film is brought into contact with the heating body and driven to move, the material to be heated is brought into close contact with the surface of the film opposite to the heating body side, and the film is moved through the heating body position together with the film to move from the heating body. A heating device for applying heat energy to a material to be heated through a film, wherein the heating body has an energization heating layer which is energized from both ends with a direction intersecting a moving passage direction of the material to be heated being a longitudinal direction, The energization heat generating layer has a branch electric path branched from at least one predetermined position in the middle of the energization exothermic layer and selectively energized, and the resistance value per unit length of the branch electric path and that of the energization heat generating layer are A heating device characterized by being different.

(2) The heating device according to (1), wherein the resistance value per unit length of the branch circuit is larger than that of the energization heat generating layer.

[0017]

[Function] When the resistance value of the branch circuit is increased, the heat generation amount of the energization heat generation layer of the non-sheet passing portion increases (the heat generation amount of the branch electrical path decreases) during branch energization, and the heating element branches in the non-sheet passing portion. The sum of the calorific values of the electric circuit and the energization heat generating layer is increased, and the temperature of the heating body of the non-paper passing portion can be maintained almost equal to the temperature of the heating body of the paper passing portion, and the paper passing portion and the non-paper passing portion are included. It is possible to make the effective full-length region of the heating element have the same temperature distribution state, and it is possible to suppress instability of the running property of the film due to the temperature decrease phenomenon in the non-sheet passing portion.

[0018]

【Example】

(1) Heating Device (FIG. 1) FIG. 1 is a schematic configuration diagram of an example of a film heating type heating device according to the present invention. This example is an image heating and fixing device of an image forming apparatus.

Reference numeral 9 denotes an endless belt-shaped fixing film (heat-resistant film), which is fixedly supported below the drive roller 8 on the left side, the driven roller 11 on the right side, and both rollers 8 and 11. The low heat capacity linear heating element 12 as a heating element and the three members 8/11/12 parallel to each other
It is suspended between them.

The driven roller 11 also serves as a tension roller for the endless belt-shaped fixing film 9, and the fixing film 9 is rotationally driven at a predetermined peripheral speed in the clockwise direction as the driving roller 8 is rotationally driven in the clockwise direction. It

Reference numeral 17 denotes a pressure roller having a rubber elastic layer having good releasability such as silicon rubber as a pressure member.
The endless belt-shaped fixing film 9 is sandwiched by the descending film portion and is pressed against the lower surface of the heating body 12 by a biasing means with a contact pressure of, for example, a total pressure of 4 to 7 kg. It rotates in the counterclockwise direction, which is the forward direction of the transport direction.

Since the endless belt-shaped fixing film 9 which is rotationally driven is repeatedly subjected to heat fixing of the toner image, it is excellent in heat resistance, releasing property, and durability, and generally 1
A thin film having a thickness of 00 μm or less, preferably 50 μm or less is used. For example, polyimide, polyetherimide, P
A single layer film of a heat-resistant resin such as ES / PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin) or a composite layer film, for example, PTFE (tetrafluoroethylene resin) on at least the image contact surface side of a 20 μm thick film. ) · A release coating layer having a conductive material added to a fluororesin such as PAF and having a thickness of 10 μm.

The low heat capacity linear heating element 12 as a heating element is a laterally long member having a longitudinal direction in the transverse direction of the fixing film (direction perpendicular to the running direction of the fixing film 9), and as shown in FIG. The heater substrate 13, the energization heat generation layer 14, the branch electric paths 14b, 14c, 14e for limiting the heat generation range with respect to the length of the energization heat generation layer 14, the energization electrodes 18a to 18e, and the temperature sensor (temperature detection element) 10.
And the like, and is held and fixedly supported by the heater support 15.

The heater support 15 serves to secure the overall strength of the heating element 12 and to insulate the heating element from the fixing device and the image forming apparatus. For example, PPS (polyphenylene sulfide), PAI (polyamide imide), It can be made of high heat resistant resin such as PI (polyimide), PEEK (polyether ether ketone), liquid crystal polymer, or a composite material of these resins and ceramics, metal, glass or the like.

The heater substrate 13 has heat resistance and electric insulation, and as an example, the thickness is 1.0 mm and the width is 10 m.
It is an alumina substrate with m and a length of 240 mm.

The heating layer 14 is, for example, the heater substrate 1
An electric resistance material such as Ta ₂ N / silver-palladium having a width of 1.
It is a linear or band-shaped low-heat-capacity energization heating layer provided by coating (screen printing, etc.) on 5 mm.

The temperature sensor 10 is arranged on the surface of the heater substrate 13 opposite to the side on which the electric heating layer 14 is provided.
In this example, the temperature of the heater substrate 13 is detected by the temperature sensor 10 as the temperature of the heating body 12.

In the case of the present embodiment, the linear or strip-shaped energization heat generating layer 14 is energized from both longitudinal ends thereof. The energization is, for example, a pulsed waveform of a DC power supply, and the temperature sensor 1
0 and a pulse (driving pulse) according to a desired temperature and energy release amount controlled by the microcomputer MPU 19 (FIG. 2) are provided by changing the pulse width thereof.

(2) Fixing Execution Operation The unfixed toner image T _a conveyed from the image forming unit side (F) to the fixing device by the image forming unit (not shown) performing an image forming operation by the image forming start signal The recording material 16 carried on the upper surface is guided by the guide to guide the heating body 12 and the pressure roller 17 to each other.
When the unfixed toner image surface comes into close contact with the lower surface of the fixing film 9 in the surface moving state, the moving fixing film 9 enters the fixing film 9 in the pressure contact portion N (fixing nip portion) with the pressure roller 17. While passing through the fixing nip portion N between the heating body 12 and the pressure roller 17 in the overlapping state, the heating body 12 and the pressure roller 17 are subjected to a nipping pressure.

The toner image bearing surface of the recording material 16 receives the heat of the heating body 12 through the fixing film 9 while passing through the fixing nip portion N in a pressing contact state with the fixing film 9, and the toner image T _a There soften the adhesive of T _b to the recording material 16 surface is hot melt.

In the case of the apparatus of this embodiment, the recording material 16 and the fixing film 9 are separated from each other when the recording material 16 passes through the fixing nip portion N and comes out. The recording material 16 separated from the fixing film 9 is guided by a guide, and the temperature of the toner T _b higher than the glass transition point is lowered (naturally cooled or forcedly cooled) while reaching a sheet discharge roller (not shown). The temperature becomes equal to or lower than the point, solidifies _Tc, and the recording material 16 on which the image is fixed is output.

(3) Control of heating range of heating element 12 (FIG. 2) FIG. 2 is a block diagram of an energization circuit for the energization heating layer 14 of the heating element 12. 14 ・ 14b ・ 14e ・ 14c are heating elements 1
An electric heating layer formed on the lower surface, which is the film sliding surface side of the second substrate 13, and three branch electric paths of first, second, and third branches branched from predetermined positions in the middle of the heating layer. . These first, second and third branch electric circuits 14b, 14
e · 14c has a resistance value per unit length larger than that of the electric heating layer 14 by changing the material of the electric heating layer 14.

The energization heat generating layer 14 is formed in a straight line along the length of the substrate at the substantially central portion of the lower surface of the substrate 13. 18a
Reference numerals 18d denote current-carrying electrodes made of a good conductive material such as silver, which are provided at the left and right ends of the current-generating heating layer 14.

K is the effective total length area of the electric heating layer 14 between the electrodes 18a and 18d. In the case of this example, the maximum size recording material 16 which can be supplied to the apparatus and used is the A3 size, and its sheet width is It is set to the corresponding length dimension.

Further, in the case of this example, recording materials of various sizes are supplied on the basis of the so-called one-sided reference based on the base line a on the left end side of the electric heating layer 14, and the first branch electric path 14b and the second branched electric path 14b.
The branch electric circuit 14e and the third branch electric circuit 14c are respectively connected to the energization heat generating layer 14 at a position of distance h.i.j from the base line a.
It is formed by branching from the portion and each free end is extended to a position corresponding to the right end of the electric heating layer 14 or an outer position thereof.

Here, each distance h.i.j is set to a length corresponding to the width of the B5 plate, A4 plate and B4 plate in the case of this example.

18b, 18e, and 18c are branch electric lines 14
It is an energizing electrode made of a good conductive material such as silver provided on the free ends of b, 14e and 14c.

Electric heating layer 14, branch electrodes 14b and 14e
14c, energizing electrodes 18a, 18d, 18b, 18e
Since the lower surface of the heater substrate 13 a · 18c, etc. to form comprises a sliding surface of the film 9, for example, it is preferable to form a Ta ₂ 0 sliding protective layer, such as ₅ to face protection.

In this example, the temperature sensor 10 is the substrate 1
3 is disposed on the upper surface side, that is, on the side opposite to the side on which the electric heating layer 14 and the like are provided, and in the area h which is the minimum paper passing area.

Reference numeral 22 denotes an operation panel of the image forming apparatus,
The recording material size information selected and designated by the size selection key of this panel is taken into the microcomputer MPU19. The MPU 19 sends a decode signal corresponding to the designated recording material size width to the decoder 20, and the decoded signal selectively drives the heating element drive circuits A to D corresponding to the designated size width. Each of the heating element drive circuits A to D has its one terminal connected to the energizing electrodes 18d, 18c, 18e, 18 described above.
The other terminal of each circuit is connected in common and connected to the energization electrode 18a (common electrode) on the left side of the energization heating element 14 via the power supply E. Reference numeral 21 is a memory circuit.

.. When the A3 size sheet having the maximum size width is selected and designated as the recording material to be used, only the heating element drive circuit A is driven, and the voltage E is applied only between the electrodes 18a and 18d at both ends of the electric heating layer 14. Applied, first to third
Each of the branch electric circuits 14b, 14e, and 14c is kept in an open state without voltage application / energization, and only the energizing heat generating layer 14 is energized, and the effective total length region k of the energizing heat generating layer 14 is per unit length. Heat is generated with a predetermined amount of heat, and image fixing of the A3 size sheet supplied to the apparatus is executed without any trouble.

.. When the B5 plate is selected and designated as the recording material to be used, the heating element drive circuits A and D are driven to apply the voltage E between the electrode 18a and the electrodes 18d and 18b. That is, the energization system for the energization heat generating layer 14 is closed, and the energization system for the first branch electric path 14b is also closed.

As a result, the heating layer portion in the area h corresponding to the sheet passing portion of the B5 size sheet, that is, the heating layer portion from the electrode 18a on one end side of the energization heating layer 14 to the branch point of the first branch electric path 14b is a unit. Heat is generated with a predetermined heat generation amount per length, and image fixing of the B5 plate sheet supplied to the apparatus is executed without any trouble.

On the other hand, the heat generating layer portion corresponding to the non-sheet passing portion (kh), that is, the heat generating layer portion from the branch point of the first branch electric circuit 14b to the electrode 18d on the other end side of the energizing heat generating layer 14 is the first. 1
The branching circuit 14b is connected in parallel with the energizing circuit, and
Since the current is shunted to 4.14b, the calorific value of the branch circuit decreases, but the sum of the calorific values of the branch circuit + the energized heat generating layer in the non-sheet passing part increases, and the non-sheet passing part of the heating element rises in temperature. As a result, a temperature state substantially equal to that of the heating body portion corresponding to the sheet passing portion h is maintained, and the occurrence of the "non-sheet passing portion temperature decrease" phenomenon is suppressed.

.. When the A4 size sheet is selected and designated as the recording material to be used, the heating element drive circuits A and C are driven, so that the energization heat generation layer 14 and the second branch electric path 14e.
The energization system is closed, and the heat generating layer portion of the area i corresponding to the sheet passing portion of the A4 size sheet generates heat with a predetermined heat generation amount per unit length, and the image fixing of the A4 size sheet supplied to the apparatus is performed. Is executed without any trouble. The heating element portion corresponding to the non-sheet passing portion (ki) corresponds to the sheet passing portion i by the sum of the heat generation amounts of the heat generating layer portion and the second branch electric line 14e in the same reason as described above. The temperature substantially the same as that of the heating body portion is maintained, and the occurrence of the temperature decrease phenomenon of the non-sheet passing portion is suppressed.

.. When the B4 version sheet is selected and designated as the recording material to be used, the heating element drive circuits A and B are driven to close the energization system for the energization heating layer 14 and the third branch electrical path 14c, and the B4 version sheet is closed. The heat generating layer portion of the heating element region j corresponding to the sheet passing portion of the sheet generates heat with a predetermined heat generation amount per unit length, and the image fixing of the B4 plate sheet supplied to the apparatus is executed without any trouble. Non-sheet passing part (k-j)
According to the same reasoning as in the above case, the heating element portion corresponding to No. 1 has a temperature substantially equal to that of the heating element portion corresponding to the sheet passing portion j due to the sum of the heat generation amounts of the heating layer portion and the third branch circuit 14c. As a result, the temperature decrease phenomenon of the non-sheet passing portion is suppressed.

(4) Another example of the structure of the branch circuit (FIGS. 3 and 4) As a structure in which the resistance value per unit length of each branch circuit 14b, 14e, 14c is made larger than that of the energization heat generating layer 14, As shown in FIG. 3, the energization heat generating layer 14 and each branch electric line 14b
The material and layer width (for example, 1.5 mm) of 14e and 14c are the same, and the layer thickness of each branch electric circuit 14b, 14e, and 14c is set to be small, for example, 5 μm, while the layer thickness is set to 10 μm, for example, of the electric heating layer 14. Can also be

Further, as shown in FIG. 4, each branch electric line 14b.1
External variable resistors Rb, Re, and Rc are connected to the electrode portions 18b, 18e, and 18c of 4e and 14c, respectively, and the resistance value per unit of the branch circuit is generated by energizing heat generation by arbitrarily selecting the value of these external variable resistors. It is also possible to make it larger than that of the layers.

FIG. 5 shows an example of the configuration of the branch circuit in the case of supplying the recording material by the central reference conveyance.

The film 9 is not limited to the endless belt-like one, but may be a long end film wound in a roll and configured so that the film is fed out and run.

[0051]

As described above, according to the present invention, in the film heating type heating device, the heating member portion corresponding to the non-sheet passing portion when the energization heating layer of the heating member is branched and energized The temperature distribution along the length of the heating element can be suppressed and the temperature distribution along the length of the heating element can be maintained at almost the same temperature distribution state in both the paper-passing portion and the non-paper-passing portion (heater effective total length area). It is possible to suppress instability of the running property of the film (occurrence of film offset, wrinkles, etc.) due to the temperature decrease phenomenon of the non-sheet passing portion.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a heating device (image heating and fixing device) according to an embodiment.

FIG. 2 is a schematic diagram of a branch energization system for an energization heating layer of a heating element.

FIG. 3 is a cross-sectional view of a heating body showing another configuration example of the branch electric circuit.

FIG. 4 is a main part diagram of still another configuration example of the branch circuit.

FIG. 5 is a configuration example of a branch circuit in the case of recording material central reference conveyance.

[Explanation of symbols]

9 Heat resistant film 12 heating body 14 Electric heating layer 14b, 14c, 14e First to third branch electric circuits 16 Recording material Rb / Rc / Re External variable resistor

Claims (2)

[Claims] 1. A film is brought into contact with a heating body and is driven to move, a material to be heated is brought into close contact with the surface of the film opposite to the heating body side, and the film is moved through the heating body position together with the film to move from the heating body to the film. Is a heating device for applying heat energy to a material to be heated via, the heating body has an energization heat generation layer which is energized from both ends with a direction intersecting the moving passage direction of the material to be heated being a longitudinal direction. It has a branch electric circuit branched from at least one predetermined position in the middle of the length of the heat generating layer and selectively energized, and the resistance value per unit length of the branch electric path is different from that of the electric heat generating layer. A heating device characterized by the above. 2. The heating device according to claim 1, wherein the resistance value per unit length of the branch circuit is larger than that of the energization heat generating layer.