JPH07199701A - Heating device - Google Patents

Abstract

PURPOSE:To prevent local temperature drop in a heating body due to a temperature detecting element for safety measures such as a thermofuse to prevent deficiency in heating at the heating body part and simultaneously to secure the responsiveness of the thermofuse when the heating body runs out in a film heating system heating device. CONSTITUTION:In the heating device in which the heating body 3 and a material to be heated (P) are adhered closely to one surface side and the other side of a heat-resistant film 2 respectively and the heat energy of the heating body 3 is imparted via the heat-resistant film 2 to the material to be heated (P), the temperature detecting element for safety measures 11 is arranged on the surface opposed to and in the position other than that of a heat generating body 4 on the heat generating substrate 6 when the temperature-detecting element for safety measures 11 is arranged via the heat-generating body substrate 6 of the heating body 3 on the surface other than that of the heat-generating body 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention adheres a heating element to one surface of a heat resistant film and a material to be heated to the other surface to apply heat energy to the material to be heated through the heat resistant film. The present invention relates to a system (film heating system) heating device.

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

Further, it can be widely used as a means and a device for heat-treating an image carrier, for example, a device for heating a recording material carrying an image to modify the surface property (gloss etc.), a device for post-treatment and so on.

[0004]

2. Description of the Related Art Conventionally, for example, a recording material heating apparatus for heating and fixing an image includes a heating roller which is maintained at a predetermined temperature and a pressure roller which has an elastic layer and presses against the heating roller. A heat roller method is widely used in which a recording material is nipped and conveyed while being heated. Further, various methods and configurations such as a flash heating method, an open heating method, and a hot plate heating method are known and put into practical use. Further, as disclosed in US Pat. No. 3,578,797, a belt heating type is also known.

Recently, a heating element (thermal heater, hereinafter referred to as a heater) fixed and supported directly to a metal or resin holder, a heat-resistant film (fixing film) conveyed while being pressed against the heater, An unfixed image formed and carried on the surface of the recording material is applied to the surface of the recording material by applying heat from the heater to the recording material through the film. An image heating and fixing device having a film heating method and structure for heating and fixing has been devised.

[0006] For example, Japanese Patent Laid-Open No. Sho 3
The method and apparatus disclosed in Japanese Patent Laid-Open No. 6-313182 belong to this, and a thin heat-resistant film (sheet), a moving drive means for the film, and a fixed support on one side of the film with the film inside. A heater arranged on the other side, and a pressing member arranged on the other surface side so as to closely contact the visible image bearing surface of a recording material to be image-fixed to the heater via the film, The film is moved and moved at the same speed in the forward direction as the recording material to be image-fixed, which is conveyed and introduced between the film and the pressure member at least at the time of image fixing, and the running moving film is sandwiched between the heater and the pressure member. By passing through a fixing nip portion as a fixing point formed by pressure contact with the recording material, the surface of the recording material of the developed image is heated by the heater through the film to heat the developed image (unfixed toner image) with thermal energy. Give Reduction and allowed melt, then a heating means or apparatus which is based on that to separate the recording material and the film after fixing points passed in separation point.

In such a film heating type heating device, a low heat capacity heating element can be used as a heater. Therefore, compared with the conventional contact heating type heat roller type, belt heating type, etc., power saving is achieved. It becomes possible to reduce the wait time (quick start). In addition, it has an advantage that the drawbacks of the conventional heating type device can be solved, and is effective.

[0008]

When a low heat capacity heating element is used as the heater in the film heating type heating apparatus as described above, power consumption and wait time can be reduced, but the heat capacity of the heater is reduced. Since the temperature is small, if a temperature detecting element such as a thermoswitch or a thermofuse for safety measures having a heat capacity is brought into contact with this, heat is taken by these temperature detecting elements and the temperature of the heater part decreases, There arises a problem that the fixing property of the image is deteriorated only in the heater portion.

In order to solve this problem, a method of increasing the heat generation amount of the heating element of the heater at the contact portion of the temperature detecting element is used to compensate for the decrease in the heater temperature at the contact portion of the temperature detecting element. Has been. However, when the temperature detecting element is sufficiently warmed, the temperature of the heater at the contact portion of the temperature detecting element becomes too high, which causes uneven gloss of the image and image offset on the film.

Therefore, the present invention solves the above-mentioned problems in the film heating type heating device, that is, prevents a local temperature drop of the heating body due to a temperature detecting element for safety measures such as a thermofuse, and the heating body The purpose is to prevent insufficient heating in the part and to ensure the responsiveness of the thermofuse during runaway of the heating element.

[0011]

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

(1) In 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. When disposing the temperature detecting element for safety measures on the surface of the heating element other than the same surface as the heating element through the heating element substrate, the temperature detecting element for safety measures is placed on the same surface as the heating element on the heating element substrate. A heating device characterized by being placed in a non-position.

(2) In 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. A heating device characterized in that a heating element substrate of a heating element and a temperature detecting element for safety measures are brought into surface contact with each other.

(3) It is characterized in that a joint member is interposed between the heating element substrate and the safety temperature detecting element in order to bring the heating element substrate of the heating element into surface contact with the safety temperature detecting element ( 2) Heating device.

(4) The heating device according to any one of (1) to (3), wherein the heating device is an image heating device for heating a recording material on which an image is formed and carried.

[0016]

In other words, the temperature detecting element such as a thermoswitch or thermofuse for thermoprotection is brought into contact with the position of the heating element on the rear surface of the heating element forming surface of the heating element so as not to hang on the heating element. It is possible to prevent the local temperature drop of the main part of the heating element without increasing the heat generation amount of As a result, it is possible to prevent the fixing property of the image from being deteriorated. Further, even when the temperature detecting element is sufficiently warmed, problems such as uneven gloss of an image and image offset on a film are eliminated. further,
By bringing the temperature sensing element into surface contact with the heating element, the thermal response of the temperature sensing element for safety measures during the runaway of the heating element can be improved and the safety can be enhanced.

[0017]

【Example】

<Example 1> (Figs. 1 to 3) (1) Example of heating device Fig. 1A is a schematic configuration diagram of an example of a film heating type heating device. The heating device of this example is disclosed in JP-A-4-4407.
This is a tensionless type heating device (image heating and fixing device) disclosed in Japanese Patent Laid-Open No. 5 or the like.

Reference numeral 1 denotes a horizontally long stay made of heat resistant resin, which serves as an inner surface guide member of an endless heat resistant film (fixing film) 2 which will be described later.

Reference numeral 3 is a heater as a heating element, and a heating element (energized heating resistor) 4, eg Ag / Pd, is provided along a substantially central portion of a heater substrate (heating element substrate) 6 made of alumina or the like.
An electrical resistance material such as (silver palladium) having a thickness of about 10 μm,
A width of 1 to 3 mm is applied by screen printing or the like, and glass, a fluororesin or the like is coated thereon as a protective layer 5.

Reference numeral 2 is an endless heat-resistant film, which is fitted onto the stay 1 including the heater 3. The stay 1 including the heater 3 and the inner peripheral length of the endless heat-resistant film 2
The outer peripheral length of the film 2 is larger than that of the film 2 by, for example, 3 mm. Therefore, the film 2 is loosely fitted to the stay 1 including the heater 3 with a sufficient peripheral length.

In order to reduce the heat capacity of the film 2 and improve the quick start property, the film thickness of the film 2 is
A film having a total thickness of 100 μm or less, preferably 40 μm or less and 20 μm or more and having heat resistance, releasability, strength, durability, etc., or a composite layer can be used.

Reference numeral 8 denotes a film pressure roller as a rotating body which drives the film 2 by forming the fixing nip portion N with the film 3 sandwiched between the heater 3 and the core shaft 9. The roller portion 10 is made of a heat-resistant rubber elastic body having good releasability, such as silicon rubber, and is driven by an unillustrated driving means from the end portion of the core shaft 9.

The rotation of the pressure roller 8 causes the film 2 to rotate around the stay 1 while the inner peripheral surface of the heater 3 slides in close contact with the heater 3. The heater 3 is controlled to energize the heating element 4 at a predetermined timing, and becomes a heat generation state at a predetermined temperature. 7
Is a thermistor for temperature control.

The image is transferred from an image forming mechanism (not shown),
A recording material P, which is a material to be heated and carries an unfixed toner image T on its upper surface, is a fixing nip portion N between the heater 3 and the pressure roller 8.
, The toner image surface comes into close contact with the outer surface of the film 2 while passing between the film 2 and the pressure roller 8, and passes through the fixing nip portion N in the overlapping state with the film 2, The heat of the heater 3 is received via the film 2 to heat and fix the toner image T. The heater 3 is energized and controlled to generate heat at a predetermined timing. A is the recording material traveling direction.

(2) Thermofuse 11 In the heating device of this embodiment, the thermofuse 11 as a temperature detecting element for safety measures is as shown in FIG.
The heater 3 is provided on the opposite side of the heater substrate 6 on which the heating element 4 is formed, and further on the downstream side with respect to the sheet passing direction so as not to reach the area directly serving as the back surface of the heating element 4. .

When the thermofuse 11 is installed in this manner, the thermal energy taken from the heating element 4 to the thermofuse 11 is reduced. This is because the heat generation distribution of the heater substrate 6 has a temperature gradient from the central portion where the heating element 4 is formed to the end portion as shown in FIG.

Therefore, the thermofuse 11 is connected to the heating element 4
By moving from the position a corresponding to the position b to the position b deviating from the position a, it is possible to reduce the amount of decrease in thermal energy applied to the recording material P and the toner T through the film 2, and prevent the deterioration of the fixing property. it can.

However, since the thermal energy per unit time obtained by the thermofuse 11 is reduced, there is a concern that the thermal response to the heater runaway may be delayed, but by lowering the rated temperature of the thermofuse 11, a A response speed equivalent to the position can be obtained.

FIG. 3 shows the thermofuse 11 at the time of heater runaway.
3 is a graph showing the temperature rise curve of FIG. X-axis is time, Y-axis is thermofuse 1
1 temperature.

From this graph, the temperature of the thermo fuse 11 when the temperature of the fixing nip portion N reaches the smoke temperature 400 ° C. (the time when the temperature reaches 400 ° C. is t) is a position = 260 ° C. , B position = 235 ° C. Thermofuse 11 with rated temperature 240 ° C at position a
As a result of comparing the time until the thermofuse is blown during a runaway, the response speed of the thermofuse 11 is almost equal when the thermofuse 11 with the rated temperature of 216 ° C is installed at position b. It is possible to prevent the fixing property from deteriorating without slowing down.

The thermo fuse 11 is installed at a position where it does not reach the back surface of the heating element 4 through the heater substrate 6, and the end portion is more effective in preventing the deterioration of fixing property than the center portion. In this embodiment, the thermofuse 11 is installed on the downstream side with respect to the sheet passing direction A of the recording material, but it goes without saying that the same effect can be obtained by installing it on the upstream side.

<Embodiment 2> (FIG. 4) As shown in FIG. 4, in this embodiment, a heat conducting member 12 is interposed between the contact surfaces of the heater substrate 6 and the thermofuses 11, It has the same structure as. The purpose of this is to increase the contact area by making the contact surface of the thermofuse 11 flat, to accelerate the thermal response during runaway, and to improve safety.

As the heat conducting member 12, the higher the heat conductivity is, the better. In this embodiment, Al is used for the heat conducting member 12. As a result of measuring the time until the thermofuse 11 is blown when the heater is out of control, it is blown by about 10% faster than in Example 1, and the thermal response is improved.

Regarding the material of the heat conducting member 12, Al is used in the present embodiment, but a metal or alloy such as Cu or duralumin, a ceramic or carbon graphite having a high heat conductivity is preferable.

The contact surface between the heater substrate 6 and the heat conducting member 12 can be further improved in thermal responsiveness by using heat resistant grease, heat resistant adhesive or the like to improve the adhesion.

With respect to the contact surface between the thermofuse 11 and the heat conducting member 12, the same effect can be obtained by increasing the adhesion by the above-mentioned method or pressure bonding. The point is that the adhesion between the heater substrate 6, the heat conducting member 12 and the thermo fuse 11 should be improved, and the means therefor is not specified.

The purpose of the thermofuse 11 and the heat conducting member 12 is to increase the contact area with the heater substrate 6, and the shape of the thermofuse 11 is such that the thermofuse 11 and the heat conducting member 12 are joined from the beginning. It may be molded in.

<Embodiment 3> (FIG. 5) As shown in FIG. 5, the present embodiment is implemented except that the heat conducting member 13 is provided between the contact surfaces of the heater substrate 6 and the thermofuse 11. The configuration is the same as in Example 2. This is one in which the contact surfaces of the thermofuses 11 are provided on the upstream side and the downstream side in the sheet passing direction A with the position of the heating element 4 interposed therebetween. The purpose is to increase the contact area and accelerate the thermal response during runaway.

In this embodiment, Al is used for the heat conducting member 13. As a result of measuring the time until the thermofuse 11 is blown when the heater runs out of control, it was blown about 15% earlier than in Example 1, and the thermal response was improved.

Regarding the material of the heat conducting member 13, although Al is used in this embodiment, a material having a high heat conductivity such as a metal or alloy such as Cu or duralumin, ceramic, or carbon graphite is preferable.

The contact surface between the heater substrate 6 and the heat conducting member 13 can be further improved in thermal responsiveness by using heat-resistant grease, heat-resistant adhesive or the like to improve the adhesion.

With respect to the contact surface between the thermofuse 11 and the heat transfer member 13, the same effect can be obtained by increasing the adhesiveness by the above method or pressure bonding. The point is that the adhesion between the heater substrate 6, the heat conducting member 13 and the thermofuse 11 should be improved, and the means therefor is not specified.

The thermofuse 11 aims to increase the contact area of the heat conducting member 13 with the heater substrate 6, and the shape of the thermofuse is such that the thermofuse 11 and the heat conducting member 13 are joined from the beginning. It may be molded.

<Embodiment 4> (FIGS. 6 and 7) In this embodiment, as shown in FIG. 6, in order to efficiently transfer heat to the pellet 30 of the thermofuse 14, the thermofuse 14 is pelletized to the heater substrate 6. It is installed so that 30 is on the contact surface side.

FIG. 7 is a vertical cross-sectional view of the thermofuse 14 in which the second lead wire 24 is extended from the side surface of the case 21 so that the pellet 30 comes to the contact surface side.
(A) is a vertical cross-sectional view during normal operation and (B) during operation.

Reference numeral 22 is a first lead wire, which is insulated from the case 21 by attaching an insulating ceramic cylindrical member 23 to the tip thereof and inserting the cylindrical member 23 into one end of the case 21 to crimp the case. I have stopped it.

25, 26, 27, 28, 29 and 30 are arranged in the case 21 in order from the first lead wire 22 side to the second lead wire 24 side, respectively.
It is a temperature-sensitive pellet composed of a movable electrode, a disk, a second spring, a disk, and an organic material which is a temperature-sensitive member.

The first spring 25 is an insulating ceramic 23.
And the movable electrode 26, and the second spring 28 is contracted between the disk 27 and the disk 29.

The spring force of the second spring 28 is made larger than that of the first spring 25. In the normal state (A), the tension force between the discs 27 and 29 of the second spring 28 causes the first spring to move. 25 is compressed between the movable electrode 26 and the insulating ceramic cylindrical member 23,
6 is pressed against the tip portion of the first lead wire 22 to maintain electrical continuity with the first lead wire 22.

The movable electrode 26 has a metal case 2 at its outer peripheral edge.
It is in contact with the inner surface of No. 1 and keeps electrical connection with the case 21, and is free to move in the axial direction in the case.

In this normal state, the electric current to the heating element 4 of the heater 3 is the first lead wire 22, the movable electrode 26 which is in pressure contact with the tip of the first lead wire 22, the metal case 21 which is electrically connected to this. It flows in the path of the second lead wire 24.

In order to maintain the airtightness of the case 21, 31 is a sealing resin which is applied and formed between the end surface of the metal case 21 on the first lead wire mounting side and the first lead wire base in this example. It is a department.

By disposing the thermofuse 14 in contact with the heater 3, the heat of the heater 3 is transferred to the temperature-sensitive pellet 30 inside via the metal case 21 and the like.
As long as the temperature of the temperature-sensitive pellet 30 is below a predetermined operating temperature, the thermofuse 14 is kept in the normal state (A), and the thermofuse 14 supplies the heating element 4 of the heater 3 to the heating element 4. Power is supplied.

On the other hand, if the heater 3 overheats due to runaway and the temperature of the temperature-sensitive pellet 30 exceeds a predetermined operating temperature,
The temperature-sensitive pellets 30 are melted or sublimated and become liquid or disappear as shown in (B), and the temperature-sensitive pellets 30 as a spacer member between the disc 29 and the tip of the second lead wire 24 disappear.

Therefore, the spring force of the first spring 25 pushes the second spring 28 toward the second lead wire 24 side to move the movable electrode 26 away from the tip of the first lead wire 22, and the heating element of the heater 3 is released. The power supply to 4 is cut off.

By disposing the pellet 30 of the thermofuse 14 on the heater substrate 6 so as to be on the contact surface side, heat transfer to the pellet 30 at the time of heater runaway can be improved, and the longitudinal direction of the heater can be improved. Since the contact length with respect to can be shortened, the contact area can be reduced as a result, and there is an advantage that the influence on the fixing property can be reduced.

The contact surface between the heater substrate 6 and the thermofuse 14 can be further improved in thermal response by using a heat-resistant grease, a heat-resistant adhesive or the like to improve the adhesion. The point is that the adhesion between the heater substrate 6 and the thermo fuse 14 should be improved, and the means therefor is not specified.

[0058]

As described above, according to the present invention, in a film heating type heating device, a temperature detecting element such as a thermoswitch or thermofuse for thermoprotection is used as a heating element on the rear surface of the heating element forming surface of the heating element. By abutting so that the position does not overlap, the amount of heat generated at the abutting portion of the temperature sensing element is not increased, that is, local temperature drop of the main part of the heating body is prevented, and Insufficient heating can be prevented, and in the image heating apparatus, deterioration of image fixing property can be prevented. Further, even when the temperature detecting element is sufficiently warmed, problems such as uneven gloss of an image and image offset on a film are eliminated. Further, by bringing the temperature detection element into surface contact, the thermal response at the time of runaway of the heating element can be improved and the safety can be improved.

[Brief description of drawings]

FIG. 1A is a schematic configuration diagram of a film heating type heating apparatus according to a first embodiment, and FIG. 1B is a diagram showing an arrangement position of a thermofuse with respect to a heating body.

[Fig. 2] Heat distribution map of heater

[Fig. 3] Temperature rise characteristic diagram of a thermofuse when a heating element (heater) runs out of control

FIG. 4 is a view showing the arrangement position of a thermofuse with respect to a heating body in the device of the second embodiment.

FIG. 5 is a diagram showing the arrangement position of a thermofuse with respect to a heating body in the device of the third embodiment.

FIG. 6 is a view showing the arrangement position of a thermofuse with respect to a heating body in the device of the fourth embodiment.

7A and 7B are vertical cross-sectional views of a temperature-sensitive pellet type thermal fuse in normal operation and in operation, respectively.

[Explanation of symbols]

1 ... Stay, 2 ... Fixing film, 3 ... Heater, 4 ... Heating element, 5 ... Protective layer, 6 ... Heater substrate, 7 ... Temperature detecting element,
8 ... Pressure roller, 9 ... Pressure roller center shaft, 10 ... Pressure roller roller portion, 11 ... Thermofuse, 12 ... Thermal conductive member, 13 ... Thermal conductive member, 14 ... Thermofuse, 21
... case, 22 ... first lead wire, 23 ... insulating ceramic cylindrical member, 24 ... second lead wire, 25 ... first spring, 26 ... movable electrode, 27 ... disk, 28 ... second spring, 29 ... disk , 30 ... Pellet, P ... Recording material, T ... Toner, N ... Fixing nip, A ... Film (recording material) traveling direction

Claims (4)

[Claims] 1. A heating device for closely contacting a heating body on one surface side of a heat resistant film and a heating target material on the other surface side, and applying heat energy of the heating body to the heating target material through the heat resistant film, When arranging the temperature detecting element for safety measures on a surface other than the same surface as the heating element through the heating element substrate of the heating element, the temperature detecting element for safety measures is placed on the same surface of the heating element substrate on the surface opposite to the heating element. A heating device characterized by being placed in a place other than the above. 2. 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 the heat energy of the heating element is applied to the material to be heated through the heat resistant film, A heating device in which a heating element substrate of a heating element and a temperature detecting element for safety measures are brought into surface contact with each other. 3. A joining member is interposed between the heating element substrate and the safety temperature detecting element to bring the heating element substrate of the heating element into surface contact with the safety temperature detecting element. 2 heating devices. 4. The heating device according to claim 1, wherein the heating device is an image heating device that heats a recording material on which an image is formed and carried.