JPH0582240A - Heating device - Google Patents

Abstract

PURPOSE:To remove any over-heating phenomenon and a leg of temperature control caused by a response lag of a temperature detecting element arranged on a heating body so as to enhance safety and reliability, such a heating device that the heating body is brought in close adhesion to one surface side of a heat-resistive film, a material to be heated is brought in close adhesion to the other side, and heat energy in the heating body is given to the material to be heated through the heat-resistive film. CONSTITUTION:A heating body temperature detecting element 23b is brought in contact with the heater substrate 21 of a heating body 20, the temperature detecting element 23b is fitted into a recessed part 21a formed on the heater substrate 21 by approximately following the shape of the temperature detecting element 23b, so as to be brought in close adhesion to the heater substrate 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-resistant film having a heating body adhered to one side thereof and a heat-resistant material to the other side thereof, and the heat energy of the heating body is applied to the heat-resistant material through the heat-resistant film. The present invention relates to a heating device of a giving method (film heating method).

This device is an electrophotographic copying machine, printer,
An image heating and fixing device in an image forming apparatus such as a fax, that is, a recording material (electrofax sheet, toner, etc.) made of a heat-meltable resin by an appropriate image forming process means such as electrophotography, electrostatic recording and magnetic recording.
A recording material carrying an unfixed toner image corresponding to the target image information formed on the surface of an electrostatic recording sheet, transfer material sheet, printing paper, etc. by a direct method or an indirect (transfer) method. It can be used as a device for heat fixing processing as a permanently fixed image on the surface.

Further, for example, it can be widely used as a means for heating a material to be heated, such as an apparatus for heating a recording material carrying an image to modify the surface property (gloss, etc.), an apparatus for presumptive treatment, and the like. ..

[0004]

2. Description of the Related Art Conventionally, as a heating device of a recording material for heating and fixing an image, for example, a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and being in pressure contact with the heating roller. A heat roller method is widely used in which a recording material is nipped and conveyed while being heated. Various methods such as flash heating method, oven heating method, hot plate heating method, etc.
The configuration is known and is in practical use.

A belt heating type is also known, as disclosed in US Pat. No. 3,578,797. this is,. The toner image is contacted with the heating element web and heated to its melting point to melt, After melting, the toner is cooled to a relatively high viscosity ,. In the process of peeling the toner from the heating body web while weakening the tendency of the toner to adhere to the heating body web, a fixing process is performed without causing offset.

Recently, a heating element fixedly supported by a metal or resin holder (thermal heater, hereinafter referred to as heater)
A heat-resistant film (fixing film) that is conveyed while being pressed against the heater, and a pressure member that brings the recording material into close contact with the heater via the film, and the heat of the heater is applied via the film to the recording material. A fixing device (film heating method) has been devised, which has a system and configuration in which an unfixed image formed and carried on the surface of the recording material is heated and fixed on the surface of the recording material by applying it to the recording material surface.

According to the applicant's earlier proposal, for example, Japanese Patent Laid-Open No.
The method and apparatus disclosed in Japanese Patent Laid-Open No. 3-313182 belong to this, and a thin endless or endless heat resistant film (sheet).
A moving drive means for the film, a heater fixedly supported on one side of the film with the film in the middle, and a heater disposed on the other side of the film so as to face the heater. The film has a pressure member for closely contacting the developed image bearing surface of the recording material to be image-fixed, and the film is conveyed and introduced between the film and the pressure member at least during image fixing. A visible image of the recording material by running and moving in the forward direction at the same speed as the recording material and passing through a fixing nip portion as a fixing portion formed by press contact between a heater and a pressing member with the traveling moving film interposed therebetween. The supporting surface is heated by the heater through the film to apply thermal energy to the developed image (unfixed toner image) to soften / melt it, and then the film and recording material after passing through the fixing portion are separated at the separation point. Based on A heating means and equipment.

In such a film heating system,
A low heat capacity heating element can be used as the heater. Therefore, it is possible to save power and shorten the wait time (quick start) as compared with the conventional contact heating method such as a heat roller method and a belt heating method. In addition, it has an advantage that the drawbacks of the conventional heating method can be solved, and is effective.

[0009]

In the film heating system as described above, the heating element is controlled to a predetermined temperature by a temperature adjusting device including a temperature detecting element such as a thermistor for temperature adjustment which is in contact with the heating element. It Further, a temperature detecting element such as a thermo switch or a thermo fuse for safety measures is brought into contact with the heating element to shut off the power supply to the heating element when the temperature of the heating element abnormally rises due to a malfunction of the temperature control device or the like. I have to.

On the other hand, in the film heating type heating device, it is possible to save power and shorten the wait time by using the low heat capacity heating element as the heating element, as described above. When the temperature rises abnormally due to a malfunction of the controller, for example, the temperature rises abruptly compared to the case of a heat roller with a large heat capacity in a heat roller type heating device, and the rapid temperature rise speed causes the thermoswitch, thermofuse, etc. The temperature sensing element for safety measures cannot keep up with the response, and the heating element may rise to a dangerous temperature before the power is cut off due to the operation of the thermoswitch or the like.

An object of the present invention is to solve the above problems in a film heating type heating device.

[0012]

According to the present invention, a heating body is adhered to one surface side of a heat resistant film and a material to be heated is adhered to the other surface side thereof,
In a heating device for applying heat energy of a heating body to a material to be heated through the heat resistant film, a heating body temperature detecting element is in contact with a heater substrate of the heating body, and the temperature detecting element is provided on the heater substrate. The heating device is characterized in that the heating device is fitted in a recess formed so as to substantially conform to the shape of the temperature detecting element and is closely attached to the heater substrate.

[0013]

In other words, the temperature detecting element to be brought into contact with the heating element is fitted into the recess formed in the heater substrate of the heating element so as to substantially conform to the shape of the temperature detecting element and closely arranged on the heater substrate. Since the contact heat-receiving area of the detection element with respect to the heater substrate, that is, the heating body, is increased as compared with the point-shaped or linear contact of the element with the heater substrate when the temperature detection element is brought into contact with the flat surface of the conventional heater substrate. The response of the temperature detecting element to the heating rate of the heating body is enhanced.

Therefore, the above-mentioned overheating phenomenon of the heating element due to the response delay of the temperature detecting element for safety measures such as the thermoswitch and the thermofuse can be eliminated to further enhance the safety.

[0015]

【Example】

<First Embodiment> (FIGS. 1 to 3) This embodiment is a heating device as an image heating and fixing device in an image forming apparatus (not shown). In FIG. 1, reference numeral 24 denotes an endless belt-shaped fixing film, which includes a left driving roller 25, a right driven roller 26, and the driving roller 25.
And the low-heat-capacity linear heating element 20 as a heating element disposed below the driven roller 26, which are parallel to each other.
Suspended on May 26th.

The driven roller 26 also functions as a tension roller for the endless belt-shaped fixing film 24.
The fixing film 24 has a predetermined peripheral speed in the clockwise direction as the driving roller 25 is driven to rotate in the clockwise direction, that is, the unfixed toner image Ta conveyed from the image forming unit (A) side (not shown).
The transfer material sheet (recording material) P having the upper surface thereof is rotatably driven at the same peripheral speed as the conveying speed of the transfer material sheet (recording material) P without wrinkling, meandering, or speed delay.

Reference numeral 28 is a pressure roller having a rubber elastic layer having a good releasing property such as silicon rubber as a pressure member,
The lower side film portion of the endless vest-shaped fixing film 24 is sandwiched and the lower surface of the low heat capacity linear heating body 20 is biased by a biasing means (not shown), for example, a total pressure of 4 to 12
They are pressed against each other with a pressing force of kg, and rotate in the forward counterclockwise direction in the conveying direction of the transfer material sheet P.

Since the endless belt-shaped fixing film 24 which is rotationally driven is repeatedly subjected to heat fixing of the toner image, it has excellent heat resistance, releasability and durability, and is generally 100 μm or less. It is preferable to use a thin film having a thickness of 40 μm or less. For example, a single layer film of a heat-resistant resin such as polyimide, polyether imide, PES, PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin) or a composite layer film, for example, 20
At least on the image contact surface side of the μm thick film, PTFE
(Tetrafluoride ethylene resin) -A resin having a releasable coating layer of a conductive resin added to a fluororesin such as PAF and having a thickness of 10 μm.

The low heat capacity linear heating element 20 as a heating element (heater) in this example is a current-carrying heating element 22 having a longitudinal direction in the transverse direction of the fixing film (direction perpendicular to the running direction of the fixing film 24) and temperature. The heater substrate 21 includes the detection element 23a (23b) and the surface layer 30. The heating body 20 is fixed and supported by a horizontally long heater support 27 having rigidity, high heat resistance, and heat insulation.

The heater support 27 insulates the linear heating element 20 from the heat of the entire machine. For example, PPS (polyphenylene sulfide), PAI (polyamide imide), P
It can be made of high heat resistant resin such as I (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 21 is a member having heat resistance, insulation, low heat capacity, and high heat conductivity, and as an example, the thickness is 1 mm.
It is an alumina substrate having a width of 16 mm and a length of 340 mm.

The heating element 22 is, for example, Ag / Pd (silver palladium) .Ta ₂ along the substantially central portion of the lower surface of the substrate 21.
An electrical resistance material such as N having a thickness of about 10 μm and a width of 1 to 3 mm is applied in a strip shape by screen printing or the like.

On top of that, a surface layer 3 for insulation and protection is provided.
The glass layer as 0 is provided. Furthermore, in order to further reduce the sliding friction with the fixing film 24, PFA / P
A smooth surface layer such as TFE may be coated.

The temperature detecting elements 23a and 23b (FIG. 2) are arranged on the upper surface of the heater substrate 21, that is, on the surface opposite to the side on which the heating element 22 is formed, along the length of the heater substrate 22 as shown in FIG. An element 23a for temperature control and a cylindrical thermofuse 23b for safety measures, which are arranged in contact with each other, are provided.
In the present embodiment, the temperature detecting element 23a for temperature control is a coating temperature measuring resistor having a low heat capacity such as a pt film.

In the heating element 20 of the present embodiment, the heating element 22 in the form of a strip is energized by the energizing electrodes at both ends in the longitudinal direction, and the heating element 22 is caused to generate heat over its entire length. Energization is A
It is C100V, and the energization power is controlled by controlling the energization phase angle of the power supply unit 33 by the energization control circuit 32 including the triac according to the detected temperature of the temperature adjustment temperature detection element 23a.

The image forming section (A) operates in response to the image forming start signal, and the recording material P having the unfixed toner image Ta carried on the upper surface, which is conveyed from the image forming section to the fixing device.
Is guided by the guide to the fixing film 24 and the pressure roller 2 at the pressure contact portion (fixing portion) N between the heating body 20 and the pressure roller 28.
8 and the unfixed toner image surface comes into close contact with the lower surface of the fixing film 24 which is rotated in the same direction as the conveyance speed of the recording material sheet P in the same direction to cause surface deviation or wrinkling. Instead, it passes between the heating member 20 and the pressure roller 28 in the overlapping state together with the fixing film 24 while receiving a clamping pressure. Since the heating element 20 is electrically heated at a predetermined timing in response to the image formation start signal, the toner image Ta is heated at the press contact portion N and becomes the softened / melted image Tb.

At the edge portion S (having a radius of curvature of about 2 mm) of the heater support 27 having a large curvature, the fixing film 24 turns at a steep angle (the bending angle θ is about 45 °) and turns. Therefore, the sheet P conveyed through the pressure contact portion N in a state of being overlapped with the fixing film 24 is curvature-separated from the fixing film 24 at the edge portion S and is discharged. By the time the paper is ejected, the toner is sufficiently cooled and solidified and is in a state of being completely fixed on the sheet P (toner image Tc).

The heating element 20 includes a heating element 22 and a heater substrate 2.
Since the heat capacity of 1 is small and these are adiabatically supported by the support body 27, the surface temperature of the heating body at the press contact portion N is short in relation to the melting point of toner (or the temperature at which the sheet P can be fixed). Since the temperature is raised to a sufficiently high temperature, it is not necessary to raise the temperature of the heating body 20 in advance (so-called standby temperature adjustment), energy can be saved, and the temperature rise inside the machine can be prevented.

In this embodiment, the cylindrical thermofuse 23b as a temperature detecting element for safety measures is such that the thermofuse 23b is semi-embedded in the heater substrate 21 of the heating body 20 as shown in FIGS. A semi-cylindrical concave portion 21a to be fitted is formed, fitted into the concave portion 21a, and closely attached to the heater substrate 21.

With this structure, when the contact heat receiving area of the thermofuse 23b with respect to the heater substrate 21, that is, the heating body 20, is in a point-like or plane-like contact state in which the thermofuse 23b is only in contact with the conventional heater substrate flat portion. In addition to being much wider than the thermo fuse 23b,
2, the heater substrate 21 or the heating element 20
The thermofuse 23b exhibits a very fast response to the abnormal temperature rise and the higher safety can be secured.

<Second Embodiment> (FIG. 4) In this embodiment, the recess 21a in the first embodiment is made into a recess having a large depth, and the thermofuse 23b is fitted into the recess 21a. After that, the effect of the first embodiment is further enhanced by closing the recess with a member 21b having good thermal conductivity such as alumina.

<Third Embodiment> (FIG. 5) In this embodiment, as a temperature detecting element for safety measures, a thermoswitch 23c in which a contact portion with the heater substrate 21 draws a convex curve is used. The arc switch concave portion 21a, which substantially follows the convex curve of the thermoswitch, is fitted into the thermoswitch contact portion 21 of the thermoswitch 21, and the thermoswitch 23c is placed in contact with the heater substrate 21.

Generally, the thermoswitch is inferior in response to the thermofuse, but has an advantage that it can be restored. By disposing the thermoswitch on the heater substrate 21 as in the present embodiment, it is possible to improve the responsiveness and take advantage of the restoration.

In the above embodiments, the temperature detecting element is a thermo fuse or a thermo switch as a safety measure, but when the temperature detecting element for temperature control is a thermistor or thermocouple, the temperature detecting element for temperature control is also By applying the invention, the response of the element is improved, and the effect of reducing the temperature control delay (time lag) can be obtained.

[0035]

As described above, according to the present invention, in the film heating type heating device, the overheating phenomenon and the temperature control delay of the heating body due to the response delay of the temperature detecting element disposed in contact with the heating body are prevented. It can be removed to improve safety and reliability.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an image heating and fixing device as an example of a heating device of the present invention.

FIG. 2 is a perspective view of a heating element.

FIG. 3 is an enlarged cross-sectional model view taken along line (3)-(3) of FIG.

FIG. 4 is an enlarged cross-sectional model view of a heating body of the second embodiment device.

FIG. 5 is an enlarged cross-sectional model view of a heating body of the third embodiment device.

[Explanation of symbols]

24 Heat Resistant Film (Fixing Film) 20 Heater 21 Heater Substrate 22 Heater 23a Temperature Sensing Element (for Temperature Control) 23b Temperature Sensing Element (for Safety Measures) 23c Temperature Sensing Element Insertion Concave Formed on the Heater Substrate P Heated Material (recording material sheet)

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Koichi Okuda 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Junji Araya 3-30-2 Shimomaruko, Ota-ku, Tokyo Kya Non-corporation (72) Inventor Shunji Nakamura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (1)

[Claims] 1. A heating device in which a heating element is adhered to one surface side of a heat resistant film and a material to be heated is adhered to the other surface side, and heat energy of the heating element is applied to the material to be heated through the heat resistant film, The heating element has a heating element temperature detecting element which is in contact with the heater substrate of the heating element, and the temperature detecting element is fitted into a recess formed in the heater substrate so as to substantially conform to the shape of the temperature detecting element and closely arranged on the heater substrate. A heating device characterized in that