JPH1184923A - Heating device, fixing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make temperature distribution in the width direction of a base plate equal right and left, to reduce thermal stress exerted on the base plate and to reduce damage and fault to surely fix an unfixed toner image with good efficiency in the case of using the base plate in a fixing device by printing and baking a heating resistor positioned at a hole for fitting connector on a heater holder so that it may be symmetric right and left with respect to the center in the width direction of a surface base plate. SOLUTION: The heating resistor 4a is printed and baked symmetrically right and left with respect to the center of the width of the surface base plate so as to equalize the temperature distribution in the width of the surface base plate at a part A where the heating device 50 constituted so that a surface heater 1 is held by the heater holder 13 corresponds to a part of a pressure roller 14. The hole 13a formed on the heater holder 13 is a hole for fitting a connector applying a commercial power source by using an electrode pattern formed on the surface of the heater 1 and an electrode pattern formed on the back surface of the heater 1. Since the width of the resistor 4a is made symmetric right and left, the temperature distribution in the width direction of the base plate is equal right and left and the thermal stress exerted on the base plate 2 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device having a planar heater, a fixing device for melting an unfixed toner image on a material to be heated by using the heating device as a heat source, and a laser beam printer having the fixing device. , Laser beam FAX
And the like.

[0002]

2. Description of the Related Art FIG. 10 is a structural view showing a conventional planar heater, FIG. 10 (a) is a front view, and FIG. 10 (b) is a rear view. In FIG. 10, reference numeral 101 denotes a planar heater;
This planar heater 101 is a planar substrate 10 having good thermal conductivity.
2, a primary-side electrode pattern 103 to which a power supply (not shown) is to be connected, a strip-shaped heating resistor 104 having one end connected to the primary-side electrode pattern 103 and printing and firing on a planar substrate;
One end is connected to the heating resistor 104, and the power supply pattern 105 printed and baked on the planar substrate in parallel with the heating resistor 104, the secondary electrode pattern 107 from which the output of the temperature sensor 106 is to be taken out, the power supply pattern 105, The back surface of the planar substrate 102 is provided with a through hole 108 for connecting an electrode pattern 109 printed and fired, and the secondary electrode pattern 107 is provided with a through hole 110 for connecting an electrode pattern 111 printed and fired on the surface of the planar substrate 102. Reference numeral 112 denotes an insulating protective layer made of glass or the like that covers the heating resistor 104 and the power supply pattern 105.

FIG. 11 is an enlarged view showing the correspondence between a heating device 100 in which the sheet heater 101 of FIG. 10 is held by a heater holder 113 and a part of a pressure roller 114, and FIG. 115 to the pressure roller 11
FIG. 4 is a front view of the fixing device in which the heater holder 113 is pressed against the receiving member 116 while being pressed by 4. Also,
The hole 113a provided in the heater holder 113 is
A connector fitting hole for supplying a commercial power supply using the electrode pattern 103 formed on the front surface of the surface heater 01 and the electrode pattern 9 formed on the back surface of the surface heater.

[0004] The film 115 is grounded. Therefore, the edge of the power supply pattern 105 and the heating resistor 1
04 are creepage distances to the planar substrate edges (in this case, the distances l1, 1 between the primary lines and the FG lines).
12 (see FIG. 13)), the heating resistor printed in parallel with the power supply pattern 105 is formed by printing and firing with a uniform width. Further, the area W where the power supply pattern 105 is not printed, and the connector fitting hole 11 provided in the heater holder 114.
3a (portion B in FIG. 13) is formed with the same width as in the above configuration.

[0005]

However, in the conventional heating device, the heating resistor located in the connector fitting hole provided in the heater holder is compared with the heating resistor located in other than the connector fitting hole. Since the amount of heat transferred to the connector is small, the temperature rise at this connector fitting hole position is high. Further, when a thick paper sheet, which is an image forming sheet as a material to be heated, is conveyed, as shown in FIG. 11, since the heating resistor is longer than the paper width, there is a gap between the opposing pressure roller and the sheet heater. A gap is generated, and the heat generating resistor located outside the thick paper sheet transport area has a small amount of heat conduction to the pressure roller and the image forming paper, and the temperature rise at the connector fitting hole position increases.

For this reason, in a configuration in which the heating resistor and the power supply pattern are present on the same plane of the substrate, if the heating resistor is not located at the center in the width direction of the planar substrate in order to secure a creepage distance. As shown in FIG. 14, the heat distribution becomes unbalanced, the thermal stress applied to the planar heater increases, and the stress applied to the planar substrate near the position of the connector fitting hole increases, thereby damaging the planar substrate. There was a problem that it may lead to.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and prevents the temperature distribution in the width direction of a planar substrate from being unbalanced to equalize the thermal distribution and reduce the thermal stress applied to the planar heater. The purpose is to reduce.

Another object of the present invention is to provide a fixing device that uses the above-described heating device as a heat source and reliably melts and fixes an unfixed toner image on a material to be heated.

Another object of the present invention is to provide an image forming apparatus capable of performing high quality fixing by applying the fixing device.

[0010]

SUMMARY OF THE INVENTION The present invention provides a heating device, a fixing device, and an image forming apparatus having the following features.

(1) A sheet heater in which a heating resistor and a power supply pattern are formed on the surface of a sheet substrate, and an electrode pattern for the heating resistor and the power supply pattern are formed on the front and back surfaces of the sheet substrate, Wherein the heating resistor positioned in the connector fitting hole of the heater holder is printed and fired on the sheet substrate so that the temperature distribution in the width direction of the sheet substrate becomes uniform. Heating equipment.

(2) A sheet heater in which a heating resistor and a feeding pattern are formed on the surface of the sheet substrate, and an electrode pattern for the heating resistor and the feeding pattern are formed on the front and back surfaces of the sheet substrate, Wherein the heating resistor positioned in the connector fitting hole of the heater holder is printed and baked on the sheet substrate so that the temperature distribution in the width direction of the sheet substrate becomes uniform, and the heater holder A heating device characterized in that an electrode pattern on the back surface of the planar substrate located in the connector fitting hole is printed and baked on the planar substrate so that the temperature distribution in the width direction of the planar substrate becomes uniform.

(3) The planar shape so that the resistance value per unit length of the heating resistor located in the connector fitting hole of the heater holder and the heating resistor located in other than the connector fitting hole are equal. The heating device according to claim 1, wherein the substrate is printed and baked on the substrate.

(4) A planar heater in which a heating resistor and a power supply pattern are formed on the surface of the planar substrate, and an electrode pattern for the heating resistor and the power supply pattern are formed on the front and back surfaces of the planar substrate, A heating device provided at the end of the material to be heated, the heating resistor being printed and baked on the sheet substrate so that the temperature distribution in the width direction of the sheet substrate becomes uniform. The heating device according to claim 4, wherein:

(5) A planar heater in which a heating resistor and a power supply pattern are formed on the surface of the planar substrate, and an electrode pattern for the heating resistor and the power supply pattern are formed on the front and rear surfaces of the planar substrate, In the heating device, the heating resistor positioned in the connector fitting hole of the heater holder is printed and baked on the planar substrate so that the temperature distribution in the width direction of the planar substrate is uniform, and A heating apparatus, wherein an electrode pattern on the back surface of a planar substrate located at an end of a heating material is printed and baked on the planar substrate so that a temperature distribution in a width direction of the planar substrate becomes uniform.

(6) The planar substrate such that the resistance value per unit length of the heating resistor located at the end of the material to be heated and the heating resistor located other than the end of the material to be heated are equal. The heating device according to claim 4, further comprising a planar heater printed and baked on the heating device.

(7) The heating device according to any one of claims 1 to 6, and the material to be heated is pressed against a position facing the planar heater to form an unfixed toner image on the material to be heated. A fixing device, comprising: a heat-resistant pressurizing unit for fusing and fixing.

(8) An image forming process means for forming an unfixed toner image on a material to be heated and wherein the unfixed toner image is fused and fixed on the material to be heated. An image forming apparatus comprising: the fixing device according to claim 1.

[0019]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

Embodiment 1 FIG. 1 is a configuration diagram showing a planar heater 1 according to Embodiment 1 of the present invention.
1A is a front view, and FIG. 1B is a back view. In FIG. 1, reference numeral 1 denotes a planar heater. The planar heater 1 has a primary-side electrode pattern 3 to be connected to a power supply (not shown) on a planar substrate 2 having good heat conductivity. A strip-shaped heating resistor 4 connected to the side electrode pattern 3 and printed and fired on a sheet substrate, one end connected to the heating resistor 4 and arranged side by side with the heating resistor and printed and fired on the sheet substrate Pattern 5, secondary electrode pattern 7, from which the output of temperature sensor 6 is to be taken out,
A through hole 8 connecting the power supply pattern 5 and the electrode pattern 9 printed and fired on the back surface of the planar substrate 2, and a through hole 10 connecting the secondary electrode pattern 7 and the electrode pattern 11 printed and fired on the surface of the planar substrate 2. It has. 1
Reference numeral 2 denotes an insulating protective layer such as glass that covers the heating resistor 4 and the power supply pattern 5.

FIG. 2 is an enlarged view showing a part of the correspondence between the heating device 50 holding the sheet heater 1 of FIG. 1 in the heater holder 13 and the pressure roller 14. The heating resistor 4a in the A section is a sheet substrate. In order to equalize the temperature distribution of the width, the printing is performed symmetrically with respect to the center of the width of the planar substrate. FIG. 3 is a front view of the fixing device in which the heat-resistant film 15 is pressed against the sheet heater 1 by the pressing roller 14 and the heater holder 13 is pressed against the receiving member 16. A hole 13a formed in the heater holder 13 is provided with a connector fitting for supplying a commercial power supply using the electrode pattern 3 formed on the surface of the surface heater 1 and the electrode pattern 9 formed on the back surface of the surface heater. It is a hole.

Next, the operation will be described.

When thick paper of A4 size or the like is used as the image forming paper, since the width of the thick paper is shorter than the length of the pressure roller 14, the pressure roller 14 and the sheet heater 1 in the portion A are used.
A gap is formed between the heaters 13 and the connector fitting hole 13a of the heater holder 13 is present on the rear surface of the planar heater. However, since the width of the heating resistor 4a in the A section is symmetrical with respect to the center in the width direction of the planar substrate, the temperature distribution in the width direction of the substrate becomes uniform left and right as shown in FIG. It is possible to reduce the applied thermal stress.

Generally, it is known that thermal stress increases in a range where the temperature gradient is steep in the temperature distribution in the substrate width direction. Further, in order to suppress an increase in the resistance value due to the increase in the width of the heating resistor 4a in the A portion, the resistance value is trimmed by a method such as trimming so that the resistance value per unit length of the relevant portion and other portions becomes the same. Adjust and bake.

Embodiment 2 FIG. 5 is a configuration diagram showing a planar heater 1 according to Embodiment 2 of the present invention.
FIG. 5A is a front view, FIG. 5B is a rear view, and FIG. 6 is a correspondence relationship between a heating device 51 holding the planar heater 1 of FIG. FIG. 4 is an enlarged view showing the same portions as those in the first embodiment, and the same portions are denoted by the same reference numerals, and redundant description is omitted. The difference from the first embodiment is that, as shown in part C of FIG. 6, in order to make the temperature distribution of the substrate width uniform, the heating resistor 4a is printed and fired symmetrically with respect to the center of the substrate width. As shown in FIG. 7, the electrode pattern 9a on the back surface of the substrate is also printed and fired symmetrically with respect to the center of the substrate width.

Next, the operation will be described.

When thick paper of A4 size or the like is used as the image forming paper, since the width of the thick paper is shorter than the length of the pressure roller 14, the pressure roller 14 and the sheet heater 1 in the portion C are used.
A space is formed between the heaters 13 and the connector fitting hole 13a of the heater holder 13 is present on the back surface of the planar heater. However, since the widths of the heating resistor 4a and the electrode pattern 9a in the portion C are symmetric with respect to the center in the width direction of the planar substrate,
As shown in FIG. 7, the temperature distribution in the width direction of the substrate becomes
Thermal stress applied to the substrate can be reduced.

In general, it is known that thermal stress increases in a range where the temperature gradient is steep in the temperature distribution in the substrate width direction. Further, in order to suppress an increase in the resistance value due to an increase in the width of the heating resistor 4a in the C portion, the resistance value is trimmed or the like so that the resistance value per unit length of the relevant portion and other portions becomes the same. Adjust and bake.

Embodiment 3 FIG. 8 shows the heating device 50 described above.
1 is a cross-sectional view illustrating a fixing device according to the present invention to which the present invention is applied.
In the figure, reference numeral 21 denotes a heater holder on a semicircular arc which stores and supports the planar heater 1 in a connector fitting hole 21a on the surface,
Reference numeral 22 denotes a cylindrical fixing film that is rotated and conveyed along the heater holder 21, and reference numeral 23 presses the fixing film 22 to the sheet heater 1 at a total pressure of about 4 to 15 kgf to form a nip portion N with the fixing film. The pressure roller 23 is formed by providing a protective layer 23c on the surface of a roller 23b made of a heat-resistant rubber having a central shaft 23a.

The fixing film 22 has a film pressure of 100 μm in order to reduce the heat capacity and improve the quick start property.
m, more preferably 40 μm or less and 20 μm or more PTEE, PEA, PP having heat resistance, releasability and durability.
S single-layer film or PTFE, P on the film surface such as polyimide, polyamide imide, PEEK, PES, etc.
It is composed of a composite film coated with FA and FEP as a release layer.

Next, the operation will be described. The heated material 25 having the unfixed toner image 24 formed on the surface thereof includes a pressing roller 23 which is rotated in the direction indicated by an arrow by a drive source (not shown) with the unfixed toner image 24 facing the fixing film 22. When the sheet is fed between the fixing film 22 and the passively rotating fixing film 22, the sheet is heated by the sheet heater 1 when passing through the nip while being sandwiched between the two 22 and 23, and the unfixed toner image 24 is melted and heated. It is fixed on the material 25.

Embodiment 4 FIG. FIG. 9 shows the fixing device 36 of FIG.
1 is a schematic diagram showing an image forming apparatus of the present invention to which the present invention is applied. In FIG. 9, reference numeral 31 denotes a photosensitive drum,
A photosensitive material such as amorphous Se or amorphous Si is formed on a substrate on a cylinder such as aluminum or nickel.

The photosensitive drum 31 is driven to rotate in the direction of the arrow, and its surface is first uniformly charged by a charging roller 32 as a charging device. Next, scanning exposure is performed by a laser beam 33 that is ON / OFF controlled according to the image information, and an electrostatic latent image is formed. This electrostatic latent image is developed and visualized by the developing device 34. As a development method, a jumping development method, a two-component development method, an FEED development method, or the like is used, and a combination of image exposure and reversal development is often used.

The visualized toner image 24 is transferred by a transfer roller 35 as a transfer device onto a transfer material 25 as a heated material conveyed at a predetermined timing.
1 is transferred from above. At this time, the transfer material 25 is nipped and conveyed between the photosensitive drum 1 and the transfer roller 35 with a constant pressing force.
The transfer material 25 to which the toner image 24 has been transferred is conveyed to the fixing device 36 shown in FIG. 8, and the toner image 24 is heated and melted and fixed on the transfer material 25 as a permanent image.

On the other hand, the transfer residual toner remaining on the photosensitive drum 31 is removed from the photosensitive drum 31 by the cleaning device 37, and the photosensitive drum 31 is used for the next image formation.

[0036]

As described above, according to the present invention, a heating resistor is formed on the surface of a planar substrate, and a power supply pattern and an electrode pattern for the heating resistor are formed on the front and back surfaces of the planar substrate. In the heating device held in the heater holder, the heating resistor positioned in the connector fitting hole of the heater holder was printed and fired so as to be symmetrical with respect to the center in the width direction of the planar substrate.
There is an effect that the temperature distribution in the substrate width direction can be made uniform left and right, and the thermal stress applied to the substrate can be reduced.

Further, by configuring the fixing device using the above-described heating device as a heat source, there is an effect that the unfixed toner can be efficiently and reliably fixed on the transfer material as the material to be heated with less damage and failure. is there.

Further, by applying this fixing device to an image forming apparatus, there is an effect that high quality fixing can be surely performed.

[Brief description of the drawings]

FIG. 1 is a front view and a back view showing a planar heater according to a first embodiment of the present invention.

FIG. 2 is an enlarged view showing a relationship between a heating device and a pressure roller according to the first embodiment.

FIG. 3 is a front view of a fixing device in which a pressure roller is pressed against a heating device in which a planar heater is supported by a heater holder.

FIG. 4 is a temperature distribution diagram in a width direction of the planar heater according to the first embodiment.

FIG. 5 is a front view and a rear view showing a planar heater according to a second embodiment of the present invention.

FIG. 6 is an enlarged view showing a relationship between a heating device and a pressure roller according to a second embodiment.

FIG. 7 is a temperature distribution diagram in the width direction of the planar heater according to the second embodiment.

FIG. 8 is a schematic diagram of a fixing device according to a third embodiment.

FIG. 9 is a schematic diagram of an image forming apparatus according to a fourth embodiment.

FIG. 10 is a front view and a back view showing a conventional planar heater.

FIG. 11 is an enlarged view showing a relationship between the conventional heating device and a pressure roller.

FIG. 12 is a front view of a fixing device in which a pressure roller is pressed against a heating device in which a planar heater is supported by a heater holder.

FIG. 13 is an enlarged cross-sectional view taken along the line ZZ ′ of FIG. 11;

FIG. 14 is a temperature distribution diagram in the width direction of a planar heater in a conventional heating device.

[Explanation of symbols]

1 planar heater, 2 planar substrate, 4 heating resistor, 4a
Heating resistor located in the connector fitting hole, 5 electrode pattern, 9 electrode pattern, 9a electrode pattern located in the connector fitting hole, 31 photosensitive drum (image forming process means), 32 charging roller (image forming process means), 33 laser beam (image forming process means),
34 Developing device (image forming process means).

Claims (8)

[Claims] 1. A planar heater in which a heating resistor and a power supply pattern are formed on the surface of a planar substrate, and an electrode pattern for the heating resistor and the power supply pattern are formed on the front and back surfaces of the planar substrate. In the held heating device, the heating resistor positioned in the connector fitting hole of the heater holder is printed and fired on the planar substrate so that the temperature distribution in the width direction of the planar substrate becomes uniform. Heating equipment. 2. A heater holder comprising: a heating resistor and a power supply pattern formed on the surface of a sheet substrate; and an electrode pattern for the heating resistor and the power supply pattern formed on the front and back surfaces of the sheet substrate. In the held heating device, the heating resistor positioned in the connector fitting hole of the heater holder is printed and baked on the planar substrate so that the temperature distribution in the width direction of the planar substrate is uniform, and A heating apparatus, wherein an electrode pattern on a back surface of a planar substrate located in a connector fitting hole is printed and baked on the planar substrate so that a temperature distribution in a width direction of the planar substrate becomes uniform. 3. The planar substrate so that a resistance value per unit length of the heating resistor located in a connector fitting hole of the heater holder and the heating resistor located in a position other than the connector fitting hole are equal. The heating device according to claim 1, wherein the heating device is printed and baked. 4. A sheet heater in which a heating resistor and a power supply pattern are formed on the surface of a sheet substrate, and an electrode pattern for the heating resistor and the power supply pattern are formed on the front and back surfaces of the sheet substrate. The holding device may further include a planar heater that prints and heats a heating resistor positioned at an end of the material to be heated on the planar substrate so that a temperature distribution in a width direction of the planar substrate is uniform. The heating device according to claim 4, characterized in that: 5. A sheet heater in which a heating resistor and a power supply pattern are formed on the surface of a sheet substrate, and an electrode pattern for the heating resistor and the power supply pattern are formed on the front and back surfaces of the sheet substrate. In the held heating device, the heating resistor positioned in the connector fitting hole of the heater holder is printed and baked on the planar substrate so that the temperature distribution in the width direction of the planar substrate becomes uniform, and the heating target is heated. A heating apparatus characterized in that an electrode pattern on the back surface of a planar substrate located at an end of a material is printed and baked on the planar substrate so that a temperature distribution in a width direction of the planar substrate becomes uniform. 6. A heat generating resistor located at an end of the material to be heated and a heat generating resistor located at a position other than the end of the material to be heated are formed on a planar substrate such that the resistance value per unit length is equal. 5. The printing device according to claim 4, further comprising a printed heater.
Or the heating device according to claim 5. 7. A heating device according to any one of claims 1 to 6, wherein a material to be heated is brought into pressure contact with a position facing the planar heater to fuse an unfixed toner image on the material to be heated. A fixing device comprising: a heat-resistant pressurizing unit for fixing. 8. An image forming process means for forming an unfixed toner image on a material to be heated, and fusing and fixing the unfixed toner image on the material to be heated. An image forming apparatus comprising the fixing device according to claim 1.