JPH0944013A - Heater, heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a heater from being cracked because of distortion caused by the difference of a thermal expansion coefficient even in the case of rapid heating by arranging a temperature detecting element for controlling the temperature of the heating body at a position between resistance heating elements on a go-path and a return-path. SOLUTION: This device is provided with a thermistor 12 functioning as the temperature detecting element disposed by conducting between the leading edges of conductive patterns 4d and 4e. The heat of the heating body 1 rises because 1st and 2nd resistance heating element patterns 3a and 3b in two lines forming the go-path and the return-path for energizing generate heat over entire longitudinal length by feeding between feed electrode patterns 5 and 6 from a feed circuit. The temperature rise of the heater is detected by the thermistor 12 functioning as the temperature detecting element on the back surface side of the heater, and the detected temperature information is fed back to a temperature control circuit through the patterns 4d and 4e and electrode patterns 13 and 14, and energizing is controlled so that the temperature of the heater 1 may be kept at specified temperature. Therefore, hot offset is prevented without making the temperature of the heater higher than necessary.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a heating element, a heating device, and an image forming apparatus.

[0002]

2. Description of the Related Art For example, an image heating and fixing device of an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile, etc., that is, an image forming process means such as electrophotography, electrostatic recording, magnetic recording, etc., is used to reveal the heat fixing property. The target image information is formed and carried by the indirect (transfer) method or the direct method on the surface of the recording material (transfer material sheet, printing paper, electro-fax sheet, electrostatic recording sheet, etc.) using an image agent (toner). As a heating device for heating and fixing the corresponding unfixed developer image on the surface of the recording material, a heating roller type device has been generally used.

This heating device of the hot roller type is a pressure contact nip portion between a heating roller (fixing roller) maintained at a predetermined heating temperature by a built-in heat source such as a halogen heater and an elastic pressure roller pressed against the heating roller (fixing roller). The recording material is introduced into the fixing nip portion) and nipped and conveyed to heat and fix the unfixed developer image on the surface of the recording material by the heat of the heating roller.

However, in the heating device as the image heating and fixing device of the heat roller system, the temperature of the heating roller must be constantly maintained at a high temperature so that an image can be output immediately at any time. It consumes a lot of energy, and heat is released into the machine even during standby, causing a problem of temperature rise inside the machine. Further, it takes a considerable waiting time after the power is turned on until the heating roller rises to a predetermined temperature suitable for heating the recording material as the material to be heated.

Recently, a film heating type heating device has been proposed and put into practical use (Japanese Patent Laid-Open No. 63-31318).
No. 2, Japanese Patent Laid-Open No. 1-263679, Japanese Patent Laid-Open No. 2-263679
No. 157878 / JP-A-4-44075-4408
No. 3, JP-A-4-20498-204498).

In this heating apparatus, a material to be heated is brought into close contact with a heating body via a heat resistant film, and the heating body and the heat resistant film are moved relative to each other so that heat of the heating body is applied to the heating material via the heat resistant film. It has a constitution and can be utilized as a means for heating and fixing an unfixed toner image as a permanently fixed image on the surface of a recording material carrying the image.

In addition, for example, it is widely used as a device for heating a recording material carrying an image to improve surface properties such as gloss, a hypothetical adhesion processing device, and other means for heating a sheet-shaped heating material. Can be used.

In such a film heating type heating device, since a heating body having a low heat capacity and a thin film which can quickly rise in temperature can be used, the temperature of the heating body rises in a short time, and the heating body is heated during standby. It is no longer necessary to carry out the energization heating of the recording material, and even if the recording material as the material to be heated is immediately passed, it is possible to sufficiently raise the temperature of the heating element to a predetermined temperature before the recording material reaches the fixing portion. It is possible to save power and shorten the wait time (quick start property), and to lower the temperature rise inside the machine such as the image forming apparatus. .

FIG. 11 (a) shows an enlarged cross-sectional model view of a main part of an example of a film heating type heating device (image heating and fixing device). (B) is a plane model view of the heating element with the middle part omitted and partially cut away.

A heating element (heater) 10 includes a heating element substrate (heater substrate) 2 and a resistance heating element (electric heating element) pattern 3, which is formed and provided on the surface side of the heater substrate 2.
Conductor pattern 4, conductive pattern 4a, two feeding electrode patterns 5 and 6, resistance heating element pattern 3 and conductor pattern 4
It is composed of a surface protective layer 7 and the like covering a portion.

The heater substrate 2 includes a heat resistant film 8 which will be described later, and a conveying / moving direction A of a recording material P as a material to be heated.
It is a ceramic base material with heat resistance, electrical insulation, and low heat capacity, such as alumina, which is horizontally long and thin with the direction orthogonal to the longitudinal direction as the longitudinal direction.

The resistance heating element pattern 3 is formed, for example, by applying an electric resistance material paste (resistive paste) such as silver palladium (Ag / Pb) .Ta ₂ N in a strip shape along the longitudinal direction of the ceramic substrate surface by screen printing or the like. It is formed by working and firing.

The conductor pattern 4 is formed in a strip shape along the longitudinal direction of the ceramic substrate substantially parallel to the resistance heating element pattern 3.

The two power supply electrode patterns 5 and 6 are arranged side by side on the surface of the ceramic substrate 2 on one end side.

Then, one end side of the resistance heating element pattern 3 is electrically connected to one of the two feeding electrode patterns 5 and 6 through the conductive pattern 4a. One end of the conductor pattern 4 on the same side is electrically connected to the other power supply electrode pattern 6. The other ends of the resistance heating element pattern 3 and the conductor pattern 4 are electrically connected to each other.

The conductor pattern 4 and the conductive pattern 4 described above.
a, the two power supply electrode patterns 5 and 6 are both formed by pattern-coating a conductive material paste such as Ag on the surface of the ceramic substrate 2 by screen printing or the like and firing.

The resistance heating element pattern 3 and the conductor pattern 4 which are substantially parallel to each other are between the two feeding electrode patterns 5 and 6 provided on one end side in the longitudinal direction of the ceramic base material 2 in the forward and backward paths of energization with respect to the longitudinal direction of the heating element. Is formed.

The heating element 10 is replaced with the resistance heating element pattern 3
The surface on which is formed is exposed downward, and is held and fixed by a heating body holder (stay) 11 having rigidity and heat insulation.

This heating element 10 is composed of the feeding electrode pattern 5
6, the resistance heating element pattern 3 heats up over the entire length by feeding power from a power feeding circuit (not shown), and the temperature rises, and the temperature rise corresponds to the position of the resistance heating element pattern 3 on the rear surface side of the heater substrate. The temperature is detected by a temperature detecting element (thermistor, etc.) 12 disposed in the heating element 1, and the detected temperature information is fed back to a temperature control circuit (not shown) to be heated
Energization to the resistance heating element pattern 3 is controlled so that the temperature of 0 is maintained at a predetermined temperature.

Reference numeral 8 is a heat-resistant film of polyimide or the like having a thickness of, for example, about 40 μm to 100 μm, and 9 is a pressurizing member for pressing the film 8 against the surface protection layer 7 which is the film sliding surface of the heating body 10. It is a pressure roller.

The film 8 is pressed against the heating body 10 by the pressure roller 9 and is driven by a driving means (not shown) or by a rotational driving force of the pressure roller 9 using the pressure roller 9 as a driving means in the direction of arrow A. Then, it moves while contacting and sliding on the surface of the heating element 10 (surface of the surface protective layer 7) at a predetermined speed.

The heating element 10 is formed by sandwiching the film 8 in a state where the heating element 10 is heated to a predetermined temperature by energizing the resistance heating element pattern 3 and the film 8 is slid on the heating element 10. A recording material P to be image-fixed as a material to be heated is introduced between the heat resistant film 8 and the pressure roller 9 in the fixing nip portion (pressure contact nip portion) N with the pressure roller 9 and the heat resistant film. By sandwiching and conveying the fixing nip portion N together with 8, the heat of the heating element 10 is applied to the recording material P via the heat resistant film 8 to form an unfixed visible image (toner image) on the recording material P. T is heated and fixed on the surface of the recording material P. The recording material P passing through the fixing nip portion N is separated from the surface of the film 8 and conveyed.

[0023]

The heating element 10 of the above-described example has a structure in which the two power supply electrode portions 5 and 6 for the resistance heating element pattern 3 are arranged on one longitudinal end side of the heating element substrate 2. , The heating element 1 is a power supply connector for the heating element 10.
However, there is an advantage in that the power supply wiring can be easily routed and the wiring work can be facilitated. However, in the case of the conventional heating element 10, resistance heating The body pattern 3 forms a forward path for energization, and the return path is a conductor pattern 4 which has low resistance and does not generate heat. in this case,
There is a difference in the coefficient of thermal expansion between the heating element parts on the outward path and the return path,
There was a problem that the heating element was easily cracked. Also,
There is also a problem that the width of the resistance heating element pattern 3 is limited by the withstand voltage and a sufficient heating area cannot be obtained.

Further, the resistance heating element pattern 3 of the heating element 10 is formed by printing and firing the resistance paste on the ceramic base material as the heater substrate 2. Change greatly affects the heat generation distribution, and in order to obtain the desired distribution, it is necessary to adjust the width of the pattern while measuring the resistance value of the pattern after firing, resulting in poor yield and completion. The production inconvenience such as the longer time has also occurred.

In addition, in a heating device using such a heating element 10, the accuracy of the mounting position of the heating element 10 is important, and the heating capacity may change greatly with a slight error, making it difficult to handle. became.

Furthermore, in a heating device using such a heating element, the resistance distribution of the heating element may be affected. For example, when such a heating device is used as an image heating device (image heating and fixing device) in an image forming apparatus such as an electrophotographic printer, if uneven heating occurs due to resistance distribution, gloss and wrinkles occur. In some cases, the resistance distribution of the heating element must be controlled to prevent this.

Therefore, the present invention relates to a heating element of this type, a heating device using the heating element, and an image forming apparatus equipped with the heating device as an image heating device, because of the difference in the coefficient of thermal expansion even when heated rapidly. Prevents the heating element from cracking due to strain, enables the heating area or heating time to be increased (enlarged), improves heating efficiency, and separates the heating element from the heated material at the end of heating. The purpose is to prevent complicated temperature control and cost increase thereof, and to enable accurate temperature control.

[0028]

The present invention is a heating body, a heating device, and an image forming apparatus, which are characterized by the following configurations.

(1) It has a plurality of power supply electrodes and a resistance heating element formed on a heating element substrate, and the resistance heating element forms a forward path and a return path between the power feeding electrodes, and is arranged in the longitudinal direction of the resistance heating element. A heating element characterized in that a temperature detecting element for controlling the temperature of the heating element is arranged at a position between the resistance heating elements on the outward path and the return path in the heating element width direction orthogonal to each other.

(2) In the heating element described in (1) above, the temperature of the heating element at the position between the resistance heating elements on the outward path and the return path is the highest in the heating element width direction orthogonal to the longitudinal direction of the resistance heating element. A heating element characterized in that a temperature detecting element for controlling the temperature of the heating element is arranged in a portion.

(3) The heating element as described in (1) or (2) above, wherein the resistance value per unit length of the resistance heating element is different between the forward path and the return path.

(4) The heating element as described in (1) or (2) above, characterized in that the material of the resistance heating element is different between the forward path and the return path.

(5) The heating element as described in (1) or (2) above, wherein the width of the resistance heating element is different between the forward path and the return path.

(6) The heating element described in the heating element described in (1) or (2) above, wherein the resistance heating element has different thicknesses in the forward path and the return path.

(7) A heating device using the heating element described in any one of (1) to (6) as a heating source.

(8) A film having a film, a heating body fixedly supported on one side of the film with the film inside, and a pressure member provided on the other side of the film so as to face the heating body. The material to be heated is introduced between the film and the pressure member in the nip portion formed by the heating body and the pressure member by sandwiching the material, and the nip portion is nipped and conveyed together with the film. Is a heating device for heating with the heat of the heating body through
A heating device, wherein the heating member is the heating member according to any one of claims 1 to 6.

(9) In the heating device described in (8), the material to be heated is a recording material having a toner image, and the device is an image heating device for heating and fixing the toner image on the recording material. Characteristic heating device.

(10) The image forming means for forming an image on the recording material and the heating device described in (7) or (8) heat-process the image on the recording material from the image forming means side. An image forming apparatus provided as an image heating device.

That is, a) By making the resistance heating element of the heating element a reciprocating path, it is possible to increase the heating area or heating time. This makes it possible to improve the heating efficiency for the material to be heated.

B) Further, even if heating is performed rapidly, both the forward path portion and the return path portion of the heating element generate heat, so that the difference in the coefficient of thermal expansion between both heating element portions can be eliminated or reduced. It has become possible to prevent the heating element from cracking due to distortion due to the difference in the rate.

C) The heating efficiency is improved or the heating is completed by changing the amount of heat generation by making the resistance per unit length of the resistance heating elements of the forward path and the return path different from each other in material, width and thickness. It is possible to improve the separation of the material to be heated at this time.

D) When the resistance heating element of the heating element has a reciprocating path structure, the temperature of the heating element is the highest between the resistance heating elements of the forward path and the return path. By accurately detecting and controlling the temperature of this portion, the temperature of the heating body does not rise more than necessary, and the occurrence of hot offset can be prevented in the image heating apparatus.

Further, since proper temperature control can be performed without using a plurality of temperature detecting elements corresponding to the number of resistance heating elements, it is possible to prevent the temperature control from becoming complicated and the cost from increasing. .

That is, when the resistance heating element of the heating element has a reciprocating path structure in order to increase the heating area or heating time, the heating element is formed on the surface opposite to the resistance heating element forming surface of the heating element as in the conventional case. When trying to arrange the temperature sensing element at the position on the back side of the heating element with respect to the position of the resistance heating element in the width direction, is it necessary to have a plurality of temperature sensing elements corresponding to the number of heating elements, or one temperature sensing element? Only the temperature near either side of the outward or return path will be detected. For this reason, the temperature control becomes complicated, the cost increases, and accurate temperature detection cannot be performed, resulting in hot offset or the like.

In the present invention, as described above, the position between the resistance heating elements on the outward path and the return path in the width direction of the heating element orthogonal to the longitudinal direction of the resistance heating element, particularly, the partial position where the temperature of the heating element between them is the highest. By arranging the temperature detecting element in the above, it was possible to prevent complicated temperature control and cost increase, and it was possible to prevent occurrence of hot offset and the like by performing accurate temperature control.

[0046]

BEST MODE FOR CARRYING OUT THE INVENTION

<Embodiment 1> (FIGS. 1 to 6) (1) Heating device example FIG. 1 shows a film heating type heating device 20 according to the present invention.
FIG. 3 is a schematic configuration model diagram of (image heating device, image heating fixing device). The same components and parts as those of the apparatus shown in FIG. 11 are designated by the same reference numerals, and the description thereof will be omitted.

The apparatus of the present embodiment is a pressure roller drive type apparatus, in which a cylindrical heat resistant film 8 (on a base material film such as polyimide) is attached to a heating body holder 11 holding a heating body 1 according to the present invention. A heating member is formed by loosely fitting a film coated with a releasable heat-resistant resin such as PFA or PTFE, and sandwiching the film 8 with a pressure roller 9 and pressing the heating member 1 against the heating member 1 with a predetermined pressing force. A fixing nip portion N is formed by sandwiching the film 8 between the fixing nip portion 1 and the film 1.

The pressure roller 9 is rotationally driven by the driving means M in the counterclockwise direction indicated by the arrow. The rotational force acts on the film 8 due to the frictional force between the roller 9 and the outer surface of the film 8 due to the rotational driving of the pressure roller 9, and the cylindrical film 8 holds the heating body 1 of the heating body holder 11. The outer circumference is rotated in the clockwise direction indicated by arrow A (the width direction of the heating element 1).

The film 8 is rotated by the rotation of the pressure roller 9, and the film 8 and the pressure roller 9 in the fixing nip portion N are kept in a state in which the heater 1 is heated to a predetermined temperature by energizing the heater 1. A recording material P, which is a sheet-shaped material to be heated, carrying an unfixed toner image T is introduced between them, and the material is brought into close contact with the surface of the film 8 and passes through the fixing nip portion N together with the film, thereby heating. The heat of the body 1 is applied to the recording material via the film 8, and the unfixed toner image T is thermally fixed on the surface of the recording material P. The recording material P passing through the fixing nip portion N is separated from the surface of the film 8 by curvature and is conveyed.

(2) Heating body 1 (a) of FIG. 2 is a front side model view of the heating body 1 in the apparatus of the present example, with the middle part omitted and partially cut away, and (b) a back side model view. . 3 is an enlarged cross-sectional view of the heating element 1, FIG. 4 is a temperature distribution diagram in the width direction of the heating element, FIG. 5 is a partially enlarged plan view of the first and second resistance heating element portions, and FIG. 6 is a temperature sensing element portion. It is an enlarged plane model figure of.

First and second two resistance heating element patterns 3
a and 3b are substantially parallel to each other along one surface side of a horizontally long ceramic substrate as a heater substrate 2 having a length in a direction orthogonal to the transporting / moving direction A of the film 8 and the recording material P. Has been formed. The first and second two resistance heating element patterns 3a and 3b are printed at about 800 ° C. after printing a resistance paste in which a metal such as silver and palladium is mixed with a glass paste as a strip-shaped pattern having a predetermined width and thickness. It is formed by firing at.

The two power supply electrode patterns 5 and 6 are provided side by side on the surface on one end side of the heater substrate 2 as in the heating element 10 shown in FIG.

One end of the first resistance heating element pattern 3a is electrically connected to one of the two feeding electrode patterns 5 and 6 through the conductive pattern 4a. Further, one end portion on the same side of the second resistance heating element pattern 3b is electrically connected to the other feeding electrode pattern 6 through the conductive pattern 4b. The other ends of the first and second resistance heating element patterns 3a and 3b have conductive patterns 4
It is conducted with c.

The above conductive patterns 4a, 4b, 4c, 2
Each of the two feeding electrode patterns 5 and 6 is made of a ceramic base material 2 by screen-printing a conductive material paste such as Ag.
It is formed by applying a pattern on the surface of and then firing.

The above-mentioned first and second two resistance heating element patterns 3a and 3b which are substantially parallel to each other are the heating element lengths between the two feeding electrode patterns 5 and 6 provided on one end side in the longitudinal direction of the ceramic base material 2. It forms the forward and return paths for energizing the hand.

13 and 14 are a pair of temperature measuring electrode patterns formed side by side on the other end of the heater substrate 2 on the back side.
Reference numerals d and 4e are parallel two-line conductive patterns formed by extending the electrode patterns 13 and 14 in series, respectively, along the longitudinal direction of the back surface of the ceramic substrate 2 and between the substantially central portions of the longitudinal direction of the substrate 2. . The electrode patterns 13 and 14 and the conductive patterns 4d and 4e are also formed by pattern-coating a conductive material paste such as Ag by screen printing and firing.

Reference numeral 12 is a thermistor as a temperature detecting element, which is provided so as to be electrically connected between the tips of the conductive patterns 4d and 4e.

The heating element 1 is a resistance heating element having the above-mentioned first and second sections, in which the forward and return paths of energization are formed by feeding power from a power feeding circuit (not shown) between the power feeding electrode patterns 5 and 6. The patterns 3a and 3b both generate heat over the entire length in the longitudinal direction to raise the temperature, and the temperature rise of the heating body is detected by the thermistor 12 as a temperature detecting element on the back side of the heating body, and the detected temperature information is the conductive patterns 4d and 4e. Electrode pattern 13
The current is fed back to a temperature control circuit (not shown) via 14 to control energization so that the temperature of the heating element 1 is maintained at a predetermined temperature.

First and second resistance heating element patterns 3a.3
The turn-around point of b is the conductive pattern 4c and has a low resistance to prevent heat generation in this portion.

In this example, both the first and second two resistance heating element patterns 3a and 3b forming the forward and return paths of energization generate the same amount of heat. The amount of heat generated at the forward-path side portion and the amount of heat-return side portion of the heating element 1 are substantially the same, and the thermal expansion amounts at both sides of the heating element are not significantly different. As a result, the heating element 1
The problem of cracks disappears.

By thus forming the resistance heating element of the heating element in the reciprocating path structure 3a, 3b, it is possible to increase the heating area or the heating time, and to obtain a remarkable heating effect as compared with the conventional case.

FIG. 4 is a temperature distribution diagram along the width direction of the heating element 1. With the resistance heating element patterns 3a and 3b as in this example, the temperature distribution of the heating element 1 is such that the temperatures of the forward path and the return path are superimposed.

When the material to be heated moves in the width direction of the heating element 1 (arrow A), the heating time is determined by the width of the resistance heating element pattern. Compared with No. 10, the heating body 1 of this example can obtain a higher heating effect. That is, when the heating body 1 of the present example is used, the high temperature portion of the heating body 1 comes into contact with the material P to be heated through the film 8, so that the heating efficiency is increased.

In the heating body 1 of this example, the heater substrate 2
Has a length a = 270 mm, a width b = 7 mm, and a thickness c = 0.
It is 635 mm.

The width d of each of the first and second resistance heating element patterns 3a and 3b is 1.0 mm, and the distance e between them is 0.5 mm.

The thermistor 12 as a temperature detecting element is
Width f (heating body width direction) = 1.9 mm and length g (heating body length direction) = 1.0 mm.

Conductive patterns 4d and 4e of the thermistor 12
Has a width h of 0.8 mm and a distance i between them.
Is 1.8 mm.

The thermistor 12 as a temperature detecting element is
At the position on the back surface of the heating element corresponding to the position between the resistance heating element patterns 3a and 3b on the outward path and the return path in the heating element width direction,
The longitudinal direction is arranged in the width direction of the heating element.

That is, since the temperature distribution in the width direction of the heating element 1 has a peak temperature in the central portion of the position between the resistance heating element patterns 3a and 3b on the outward path and the return path in the heating element width direction as shown in FIG. In order to prevent complicated temperature control, cost increase, and accurate temperature control for preventing the occurrence of hot offset, the thermistor 12 as the temperature detecting element is set to the heating body peak temperature portion as described above. , The resistance heating element patterns 3a and 3 on the outward and return paths in the width direction of the heating element
It is optimal to dispose at a position on the back surface side of the heating element corresponding to the position between b.

That is, the temperature distribution in the width direction of the heating element 1 of this example is such that the temperatures of the resistance heating element 3a on the outward path and the resistance heating element 3b on the return path are superposed.
The temperature near the center between the resistance heating element patterns 3a and 3b is the highest. In order to prevent hot offset, the temperature of the part where the temperature of the heating element 1 is the highest must be accurately controlled. Therefore, in this example, the temperature detecting element 12 is arranged in the central portion between the resistance heating element patterns 3a and 3b.

As a result, the temperature of the heating element 1 does not rise unnecessarily, and the occurrence of hot offset can be prevented.

Further, since appropriate temperature control can be performed without using a plurality of temperature detecting elements, it is possible to prevent the temperature control from becoming complicated and the cost from increasing.

<Embodiment 2> (FIG. 7) In the present embodiment, the thermistor 12 as the temperature detecting element is provided with the resistance heating element pattern 3a in the forward and backward directions in the width direction of the heating element as in the case of the first embodiment. Is arranged at a position on the back surface side of the heating body corresponding to a position between the positions 3 and 3b. In this case, in the above-described Embodiment 1, the thermistor 12 has its longitudinal direction as the heating body width direction. In the present embodiment, the thermistor 12 is arranged such that its longitudinal direction is the longitudinal direction of the heating body as shown in FIG.

The temperature distribution in the width direction of the heating element has a temperature peak in the central portion between the two resistance heating element patterns 3a and 3b as shown in FIG. 4, and the temperature decreases as the distance from the central portion increases. Therefore, by arranging the thermistor 12 with the longitudinal direction of the thermistor 12 in the longitudinal direction of the heating body as described above, it is possible to detect the temperature of the heating body temperature peak portion substantially in the entire thermistor 12, and It becomes possible to perform more appropriate temperature detection and temperature control as compared with the case where the longitudinal direction is arranged in the heating body width direction.

<Third Embodiment> This embodiment is the same as the first embodiment.
In the heating element 1 of FIG. 1, both the first and second resistance heating element patterns 3a and 3b are printed on the heater substrate 2 in a striped pattern by using a resistance paste in which a metal such as silver and palladium is mixed with a glass paste. It is formed by firing at about 800 ° C. In this case, the first resistance heating element 3a which is the outward path and the second resistance heating element pattern 3b which is the return path.
Are selected such that the resistance paste materials have different resistance values per unit length.

In this embodiment, the resistance value of the first resistance heating element 3a is lower than the resistance value of the second resistance heating element pattern 3b.

The heating element 1 is fed between the feeding electrode patterns 5 and 6 so that the first resistance heating element pattern 3a, which is the forward path of energization, and the second resistance heating element pattern 3b, which is the return path, are energized. It produces a different amount of heat. In the case of the heating element of this example, the forward side was lower than the return side.

As a result, the effect of cracking the heating element 1 due to the difference in thermal expansion between the forward path side portion and the returning path side portion of the heating element 1 is less effective than the heating elements 1 of the first and second embodiments. However, it is still preferable to the conventional heating element 10 of FIG.

When the material to be heated moves in the width direction of the heating element, the resistance value of the second resistance heating element pattern 3b on the downstream side (return path side) is increased and the resistance value on the upstream side (forward path side) is increased. The resistance value of the first resistance heating element pattern 3a in (1) is lowered. As a result, the amount of heat supplied to the heated object per unit time is
Since it will be determined by the temperature difference between the heated body and the heated body,
As the material to be heated warms, the heating element configuration of the present embodiment, which approaches the second resistance heating element 3b on the downstream side having a higher temperature, can obtain a higher heating effect. That is, increasing the amount of heat generation on the downstream side can further increase the heating efficiency.

On the other hand, in some cases, it is better to lower the temperature when separating the heating body and the material to be heated. For example, in a fixing device of an electrophotographic apparatus, it has been found that it is preferable to offset the toner image after the toner image is sufficiently cooled before the toner image is peeled off. That is, when this heating device is used as a fixing device particularly used in an electrophotographic printer, after the toner image on the recording material P is once heated and melted, the temperature is lowered to the melting temperature or lower, and then the film is separated from the film 8. I know that there is less offset when you do,
To such an object, contrary to the above, the resistance value of the first resistance heating element 3a on the upstream side (outward path side) of the heating element 1 is set high and the resistance value of the first resistance heating element 3a on the downstream side (return path side) is increased. By lowering the resistance value of the heating element 3b, the temperature distribution on the forward path side (upstream side) and the return path side (downstream side) along the width direction of the heating element may be set to be lower on the return path side than on the forward path side. In this way, by increasing the heat generation amount on the upstream side, the recording material P when separating on the downstream side is formed.
The temperature can be lowered to improve the separability.

As described above, which of the first and second resistance heating element patterns 3a and 3b is to be increased in resistance (heat generation amount) may be determined as necessary.

Also in the case of the heating body as in this example, the temperature of the heating body at the position between the forward and backward resistance heating element patterns 3a and 3b in the width direction of the heating body By arranging in the highest part, the same effect as in the first and second embodiments can be obtained.

<Embodiment 4> (FIG. 8) This embodiment is the first embodiment of the heating element 1 of Embodiment 1 described above.
The second resistance heating element patterns 3a and 3b are both printed on the heater substrate 2 in the form of a strip using the same resistance paste in which a metal such as silver and palladium is mixed with a glass paste, and then baked at about 800 ° C. In this case, the width of the first resistance heating element 3a which is the outward path and the width of the second resistance heating element pattern 3b which is the return path are different.

In FIG. 8A, the width of the first resistance heating element 3a which is the outward path is set to be larger than the width Wb of the second resistance heating element pattern 3b which is the return path.

In FIG. 9B, conversely, the width of the second resistance heating element 3b, which is the return path, is set to be Wb wider than the width Wa of the first resistance heating element pattern 3a, which is the outward path.

These heating elements 1 are composed of the feeding electrode pattern 5
By supplying power between six, different amounts of heat are generated in both the first resistance heating element pattern 3a, which is the outward path of energization, and the second resistance heating element pattern 3b, which is the return path.

In the case of the heating element 1 of (a), similar to the heating element in which the resistance value of the first resistance heating element 3a of the third embodiment is lower than the resistance value of the second resistance heating element pattern 3b. ,
The temperature distribution on the forward path side (upstream side) and the return path side (downstream side) becomes lower on the forward path side than on the return path side.

In the case of the heating element 1 of (b), conversely, the temperature distribution on the outward path side and the return path side is lower on the return path side than on the outward path side.

Also in the case of this embodiment, the same operation and effect as those of the heating body or the heating device of the third embodiment are provided.

Further, in the case of the present embodiment example, the first and second resistance heating element patterns 3a and 3b can be formed in one printing step in comparison with the third embodiment example, and the productivity is improved. To do.

Also in the case of the heating element as in this example, the temperature of the heating element at the position between the forward and backward resistance heating element patterns 3a and 3b in the heating element width direction is set to the thermistor 12 as a temperature detecting element. By arranging in the highest part, the same effect as in the first and second embodiments can be obtained.

Although the resistance heating element patterns 3a and 3b of the heating element 1 of the above-described first to fourth embodiments have one reciprocating movement, they may be formed in plural reciprocating movements.

It is possible to separately screen-print the resistor patterns 3a and 3b as well, and change the respective resistance values by varying the pattern thickness depending on the viscosity of the printing paste and the squeeze speed.

<Embodiment 5> (FIG. 9) FIGS. 9A, 9B, and 9C are schematic views of other structural examples of the film heating type heating device.

In (a), the endless belt is provided between the first film suspending roller 31, the second film suspending roller 32, and the heating member 1 between the three members 31, 32. -Shaped heat-resistant film 8 is stretched and stretched, and the pressure roller 9 is disposed by pressing the heat-resistant film 8 against the heating body 1 with the film 8 sandwiched between the heat-resistant film 8 and the first film suspension roller 31 or The pressure roller 9 is used as a film driving roller and is rotated and conveyed A. When the first film suspension roller 31 is used as a driving roller, the pressure roller 9 is driven to rotate.

In the case of (b), an endless belt-shaped heat-resistant film 8 is suspended and stretched between the heating member 1 and the two members 1 and 33 of the film suspension roller 33 to form the film 8
The pressure roller 9 is disposed in pressure contact with the heating body 1 with the heat-resistant film 8 being a film suspension roller 33 or the pressure roller 9 being a film driving roller, and is rotationally conveyed A. . When the first film suspension roller 33 is the driving roller, the pressure roller 2 is driven to rotate.

In the case of (c), the heat-resistant film 8 is not an endless belt-shaped one, but a long end film wound in a roll is used.
From the side to the take-up shaft 35 side via the heating body 1, the pressure roller 9 is pressed against the heating body 1 with the film 8 sandwiched therebetween, and the film 8 is run and conveyed to the take-up shaft 35 side. Is. The pressure roller 9 can also be a film drive roller.

<Sixth Embodiment> (FIG. 10) FIG. 10 shows an image forming apparatus incorporating an image heating and fixing device 20 as a film heating type heating device according to the present invention as shown in the first embodiment. The schematic structure of an example is shown. The image forming apparatus of this embodiment is a reciprocating platen type, a rotary drum type, a transfer type, and a process cartridge attaching / detaching type electrophotographic copying apparatus.

Reference numeral 100 denotes an apparatus casing, 101 denotes a reciprocating type document placing table made of a transparent plate member such as a glass plate disposed on an upper surface plate 102 of the apparatus casing.
The upper part is driven to reciprocate to the right a and the left a'in the drawing at a predetermined speed.

Reference numeral G denotes an original, which is placed on the upper surface of the original placing table 101 according to a predetermined placing standard with the image surface side to be copied facing downward, and by pressing the original pressing plate 103 to cover it. Set.

Reference numeral 104 denotes a slit opening serving as a document illuminating section which is opened on the surface of the upper surface plate 102 of the machine casing with a direction perpendicular to the reciprocating direction of the document placing table 101 (direction perpendicular to the paper surface) as a longitudinal direction.

The downward image surface of the document G placed and set on the document placing table 101 sequentially passes through the position of the slit opening 104 from the right side to the left side in the reciprocating process of the document placing table 101 to the right a. In the course of the passage, the light L of the lamp 105 is received through the slit opening 104 and the transparent original placing table 101 to be illuminated and scanned, and the original surface reflected light of the illumination scanning light is reflected by the image element array 106 by the photosensitive drum 107. The image is exposed on the surface.

The photosensitive drum 107 is coated with a photosensitive layer such as a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer, and is rotated in the clockwise direction indicated by the arrow b at a predetermined peripheral speed around the central support shaft 108. During the rotation process, the charging device 109 receives a uniform charging process of positive polarity or non-polarity, and the uniformly charged surface is subjected to the image formation exposure (slit exposure) of the original image, so that the surface of the photosensitive drum 107 is formed. An electrostatic latent image corresponding to the image-exposed original image is sequentially formed.

This electrostatic latent image is visualized in order by the developing device 110 with toner made of resin or the like that is softened and melted by heating, and the toner image as the visualized image is provided with a transfer discharger 111 as a transfer portion. It moves to the part.

Reference numeral S denotes a cassette in which transfer material sheets P as recording materials are stacked and housed, and the sheets in the cassette are fed and fed one by one by the rotation of the feeding roller 112.
Next, when the leading edge of the toner image forming portion on the drum 107 reaches the transfer discharger 111 portion by the registration roller 113, the leading edge of the transfer material sheet P is also transferred.
And the photosensitive drum 107 are just moved to a position between the photosensitive drum 107 and the photosensitive drum 107.

The toner image on the side of the photosensitive drum 107 is sequentially transferred by the transfer discharger 111 onto the surface of the feeding sheet.

The sheet to which the toner image has been transferred at the transfer portion is sequentially separated from the surface of the photosensitive drum 107 by a separating means (not shown), and is guided to the fixing device 20 by the conveying device 114 to carry the unfixed toner. The image is heated and fixed, and is discharged as an image-formed product (copy) onto the discharge tray 117 outside the apparatus through the discharge roller 116.

The surface of the photosensitive drum 107 after the image transfer is subjected to the removal of adhering contaminants such as transfer residual toner by the cleaning device 118, and is repeatedly used for image formation.

The PC is a process cartridge which is attached / detached to / from the cartridge attaching / detaching portion 120 in the apparatus main body 100.
In the case of the present embodiment, the apparatus main body 10 includes four process devices including a photosensitive drum 107 as an image carrier, a charger 109, a developing device 110, and a cleaning device 118.
0 is detachable and exchangeable.

[0110]

As described above, the heating area or the heating time can be increased by forming the resistance heating element of the heating element in the reciprocating pattern.

This makes it possible to improve the heating efficiency for the material to be heated. Further, even when heated rapidly, it is possible to prevent the heating element from cracking due to the strain due to the difference in the coefficient of thermal expansion.

Further, even if the resistance heating element of the heating element is reciprocated, the temperature detecting element is arranged so as to accurately detect the temperature of the heating element, so that optimum temperature control can be performed, and the temperature of the heating element can be controlled. In the image heating apparatus, the occurrence of hot offset can be prevented without increasing the temperature more than necessary.

Further, since proper temperature control can be performed without using a plurality of temperature detecting elements corresponding to the number of resistance heating elements, it is possible to prevent the temperature control from becoming complicated and the cost from increasing. it can.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a film heating type heating device (image heating device, image heating and fixing device) according to a first embodiment.

[FIG. 2] (a) is a front side model view of the heating element with the middle part omitted and partially cut away, (b) is a back side model view

[Fig. 3] Enlarged cross-sectional model view of a heating element

FIG. 4 is a temperature distribution diagram along the width direction of the heating element.

FIG. 5 is a partially enlarged plan view of first and second resistance heating element portions.

FIG. 6 is an enlarged plan view of the temperature sensing element portion.

FIG. 7 is an enlarged plan view of an essential part of the heating body according to the second embodiment.

8 (a) and 8 (b) are plan view model diagrams of the heating element of Embodiment 4 with the middle part omitted and partially cut away, respectively.

FIGS. 9A, 9B, and 9C are schematic diagrams of another configuration example of a film heating type heating device.

FIG. 10 is a schematic configuration diagram of an example of an image forming apparatus.

FIG. 11A is an enlarged cross-sectional model view of a main part of an example of a film heating type heating device (image heating and fixing device);
(B) is a plan view of the heating element with the middle part omitted and partially cut away

[Explanation of symbols]

 1 · 10 heating body 2 heater substrate (ceramic base material) 3 resistance heating element pattern 3a first resistance heating element pattern (outward path) 3b second resistance heating element pattern (return path) 4 conductor pattern 4a to 4c conductive pattern 5 6 Power Supply Electrode Pattern 7 Surface Protective Layer 8 Heat Resistant Film 9 Pressure Roller 11 Heating Body Holder 13 ・ 14 Electrode Pattern for Temperature Measurement P Heated Material (Recorded Material) T Toner Image N Fixing Nip Part (Pressing Nip Part)

Claims (10)

[Claims] 1. A plurality of power supply electrodes and a resistance heating element formed on a heating element substrate, wherein the resistance heating element forms a forward path and a return path between the power feeding electrodes, and is orthogonal to the longitudinal direction of the resistance heating element. A heating element for controlling the temperature of the heating element is arranged at a position between the resistance heating elements on the outward path and the returning path in the width direction of the heating element. 2. The heating element according to claim 1, wherein the portion of the heating element having the highest temperature at a position between the resistance heating elements on the outward path and the return path in the heating element width direction orthogonal to the longitudinal direction of the resistance heating element. A heating element, wherein a temperature detecting element for controlling the temperature of the heating element is arranged. 3. The heating element according to claim 1, wherein the resistance value per unit length of the resistance heating element is different between the forward path and the return path. 4. The heating element according to claim 1 or 2, wherein the resistance heating element is made of a different material for the forward path and the return path. 5. The heating element according to claim 1, wherein the resistance heating element has different widths in the forward path and the return path. 6. The heating element according to claim 1 or 2, wherein the resistance heating element has different thicknesses on the outward path and the return path. 7. A heating device comprising the heating body according to claim 1 as a heating source. 8. A film comprising: a film, a heating body fixedly supported on one surface side of the film, and a pressure member provided on the other surface side so as to face the heating body. The material to be heated is introduced between the film and the pressure member in the nip portion formed by the heating member and the pressure member by sandwiching it, and the nip portion is nipped and conveyed together with the film to transfer the material to be heated to the film. A heating device for heating with heat of a heating body via the heating body, wherein the heating body is the heating body according to any one of claims 1 to 6. 9. The heating device according to claim 8, wherein the material to be heated is a recording material having a toner image, and the apparatus is an image heating device for heating and fixing the toner image on the recording material. Heating device. 10. An image forming means for forming an image on a recording material, and an image heating for heating the image on the recording material from the image forming means side by the heating device according to claim 7 or 8. An image forming apparatus provided as an apparatus.