JPH09269696A - Heater device and fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control the temp. of the whole of a ceramic heater, even if the ceramic heater is used as a heating means by making the thickness of the contact part with a temperature detecting means of a glass member larger than that of the other covering part. SOLUTION: The surfaces of heating resistors 2 are covered with a glass member 4 and this glass member 4 is formed so that the contact part 4a with the temperature detecting means 5 is thicker than the other covering part 4b. Thus, the difference between the distances (a) and (b) from the top end of the detecting means 5 to the heating elements 2 and the distance (c) from the top end to e heater substrate 3 can be made smaller than a conventional one and heat can be transferred to the top end of the detecting means 5 at a nearly equal distance in the sectional direction of the ceramic heater 1. Moreover, it is preferable that the shape of the contact part 4a is a symmetric shape with respect to the attachment position of the detecting means 5. Further, positions where the heating elements 2 are printed are set to make the distances from the center of the detecting means 5 equal respectively. Thus, the temperatures at each point of the heater 1 can be accurately detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tape heating device used in a bookbinding apparatus or the like for binding an image-formed sheet to bookbinding, or an unfixed toner image imaged by an electrophotographic technique on a recording material. The present invention relates to a heater device used in a fixing device for fixing and a fixing device including the heater device.

[0002]

2. Description of the Related Art Conventionally, when a plurality of sheets on which an image is formed are glued together and automatically performed continuously, an online apparatus in which a plurality of apparatuses for performing necessary jobs are connected is used. I have.

For example, the above-mentioned on-line apparatus is a reading / feeding apparatus including a document setting unit for setting a document, an optical system for scanning the document, and a sheet feeding unit for storing a large number of sheets and feeding them. A paper device, an image forming device that forms an image of the fed sheet, a bookbinding device that binds the image-formed sheet, and a sorting storage device that sorts and stores the finished bound product or individual sheets It is made up of

In this apparatus, when binding in the bookbinding apparatus, a gluing binder for gluing and binding the aligned sheet bundle in the sheet alignment tray is used. The bind tape used for this is a hot-melt type tape, and is heated by a tape heating device including a heater to glue the sheet bundle.

Further, the sheets are stored in one aligning tray, and the sheets are aligned by abutting the abutting member.
The sheet bundle and the bind tape abutting on the sheet bundle are heated by one tape heating means.

Further, the heater as a heating means accommodates the heating means by a heating wire such as a nichrome wire through an insulator inside a heating medium made of metal such as aluminum having good heat conductivity or stainless steel having good heat storage. Was configured.

However, since such a heating means has a large heat capacity, it is difficult to immediately raise the temperature to the operating temperature, and a so-called wait time is required.

Therefore, in order to eliminate such a wait time, it has been considered to use a ceramic heater which is practically used as a heating means for a fixing device of an image forming apparatus.

This ceramic heater is formed by printing a resistance heating element on a thin plate-shaped ceramic surface.
Due to its extremely small heat capacity and the excellent thermal efficiency peculiar to ceramics, it can generate heat as it is energized and can immediately rise to the operating temperature, making it possible to provide a device without a wait time. In addition, it is not necessary to constantly adjust the temperature to a constant temperature and stand by, so that power saving can be realized.

7 and 8 show a schematic structure of a conventional ceramic heater. As shown in FIG. 8 which is a cross-sectional view taken along the line AA of FIG. 7, the resistance heating element 2 is printed on the surface of a ceramic heater substrate 3 formed in a thin plate shape.
The surface of is coated with the glass member 4. As shown in FIG. 7, a heater terminal 6 is connected to both ends of the resistance heating element 2, and the resistance heating element 2 generates heat when power is supplied through the heater terminal 6. Further, the heater substrate 3 is also heated, the temperature of the entire ceramic heater 1 is rapidly raised, and the heat is given to the outside.

In order to control the temperature of the ceramic heater 1, as shown in FIG. 7, the temperature detecting means 5 is brought into contact with the surface side of the glass member 4 and the temperature information from the temperature detecting means 5 is used to This is performed by controlling the supplied power by the microcomputer of the image forming apparatus main body and the heater driving (energizing heat generation) circuit.

[0012]

However, in the above conventional example, the temperature detecting means 5 cannot be brought into contact with the heating side of the heater substrate 3, and the resistance heating element 2 having the highest temperature on the ceramic heater 1 is provided. Since it is brought into contact with the surface of the glass member 4 close to, the detected temperature is strongly influenced by the heat of the resistance heating element 2, and it may be difficult to accurately detect the temperature.

That is, in the case of the ceramic heater shown in FIGS. 7 and 8, the temperature generated between the surface of the ceramic heater 1 without the resistance heating element 2 and the surface of the ceramic heater 1 where the resistance heating element 2 is present. Since the difference is not taken into consideration, it may be difficult to control the temperature of the entire ceramic heater 1.

Therefore, an object of the present invention is to provide a heater device capable of accurately controlling the temperature of the entire ceramic heater even when a ceramic heater is used as the heating means, and a fixing device equipped with this heater device. There is.

[0015]

According to a first invention of the present application, the above object is to provide a ceramic heater substrate,
A resistance heating element printed on the heater substrate, a glass member covering the heater substrate including the resistance heating element, and a temperature detecting means arranged so as to be in contact with the surface of the glass member. In the heater device, the glass member is achieved by the thickness of the portion with which the temperature detecting means is in contact being larger than the thickness of the other coating portions.

According to the second aspect of the present invention,
The above-mentioned object is achieved in the above-mentioned first invention by that the shape of the portion where the heater substrate made of ceramic and the temperature detecting means are in contact with each other is hemispherical.

Further, according to the third invention of the present application, the above object is to provide a ceramic heater substrate, a resistance heating element printed on the heater substrate, and a heater substrate including the resistance heating element. A heat-resistant film having a heater device including a glass member to be covered and a temperature detecting means arranged so as to be in contact with the surface of the glass member, and a film suspension tension member including the heater device. Is suspended and driven to run, and the material to be heated is brought into close contact with the side of the film opposite to the side of the heater device to pass through the position of the heater device, whereby the thermal energy of the heater device is transferred to the film. In the fixing device for applying to the material to be heated via, the glass member of the heater device is achieved in that the thickness of the portion with which the temperature detecting means is abutted is larger than the thickness of the other covering portion. .

According to a fourth aspect of the present invention,
In the third aspect of the invention, the above object is achieved by the shape of the portion with which the temperature detecting means is in contact is hemispherical.

That is, in the first aspect of the present invention, since the glass member for covering the heater substrate including the resistance heating element has a thicker portion at which the temperature detecting means comes into contact with the glass member, the glass member is thicker than the other portions. Accurate temperature detection is performed by detecting heat from an arbitrary point generated from the resistance heating element on the heater substrate at substantially equal distances.

Further, in the second invention of the present application, the portion of the glass member of the first invention which comes into contact with the temperature detecting means has a hemispherical shape with respect to the center of the resistance heating element as a reference. The heat generated from the resistance heating element is transmitted at the hemispherical contact portion so that the temperature change is even, and accurate temperature detection is performed.

Further, according to the third invention of the present application, in the glass member for covering the heater substrate including the resistance heating element in the heater device of the fixing device, the thickness of the portion contacting the temperature detecting means is different from that of the other coating. Since the thickness is thicker than a minute, accurate temperature detection is performed by detecting heat from an arbitrary point generated from the resistance heating element on the heater substrate at substantially equal distances, and good fixing is performed.

Further, in the fourth invention of the present application, the portion of the glass member of the third invention which comes into contact with the temperature detecting means has a hemispherical shape with respect to the center of the resistance heating element as a reference. The heat generated from the resistance heating element is transferred to the hemispherical contact portion so that the temperature change is even, and accurate temperature detection is performed, so that good fixing is performed.

[0023]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

(First Embodiment) First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view best showing the features of a heater device used in a tape heating device or a fixing device according to this embodiment.
2 is a sectional view taken along line AA of FIG.

In FIG. 1, reference numeral 1 is a ceramic heater, and a resistance heating element 2 of the ceramic heater 1 is printed on a ceramic heater substrate 3 as shown in FIG. The surface of the resistance heating element 2 has a glass member 4
In the present embodiment, the glass member 4 is formed so that the contact portion 4a of the temperature detecting means 5 is thicker than the other coating portions 4b. further,
As shown in FIG. 1, heater terminals 6 are connected to both ends of the resistance heating element 2 so that power can be supplied to the resistance heating element 2.

As described above, by increasing the thickness of the contact portion 4a of the temperature detecting means 5 of the glass member 4, the distance a from the tip of the temperature detecting means 5 to the resistance heating element 2 as shown in FIG. The difference between b and the distance c to the heater substrate is shown in FIG.
The size can be made smaller than in the case of the conventional example shown in FIG. 3, and heat can be propagated to the tip of the temperature detecting means 5 at substantially equal distances in the cross-sectional direction of the ceramic heater 1.

It is desirable that the shape of the contact portion 4a be symmetrical with respect to the mounting position of the temperature detecting means 5. In the present embodiment, as shown in FIG. 1, the lengths d, e, from the temperature detecting means 5 to the end of the contact portion 4a,
f and g are set so that d = e and f = g. This makes it possible to detect the temperature evenly on the surface of the ceramic heater.

The printing positions of the resistance heating elements 2 are set so that the distances w from the center of the temperature detecting means 5 are equal to each other.

As described above, according to the present invention, it is possible to accurately detect the temperature of each point of the ceramic heater, and it is possible to perform temperature control with higher accuracy.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The ceramic heater 1 in this embodiment
In the first embodiment, the resistance heating element 2 is not printed separately on both sides of the heater substrate 3 as in the first embodiment, but is printed uniformly over substantially the entire surface of the heater substrate 3. Different from the form.

Also in the ceramic heater 1 having such a configuration, as in the first embodiment, the contact portion 4a of the temperature detecting means 5 of the glass member 4 is formed thicker than the other coating portion 4b. By doing so, heat can be propagated to the tip of the temperature detecting means 5 at substantially equal distances in the cross-sectional direction of the ceramic heater 1. Therefore, it becomes possible to accurately detect the temperature of each point of the ceramic heater,
A more accurate temperature control can be performed.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

FIG. 4 is a perspective view of the ceramic heater of the second embodiment, and FIG. 5 is a sectional view taken along line BB in FIG.

The resistance heating element 2 on the ceramic heater 1 of this embodiment is printed on the central portion of the heater substrate 3,
The contact portion 4a of the temperature detecting means 5 on the glass member 4 that coats the resistance heating element 2 has a circular shape with the center of the resistance heating element 2 as a reference, as shown in FIG.

That is, the distances h and i from the center of the resistance heating element 2 to the surface of the contact portion 4a are equal as shown in FIG. Therefore, the heat generated from the resistance heating element 2 propagates at a uniform speed on the surface of the circular contact portion 4a, which enables stable and accurate temperature control.

(Fourth Embodiment) Next, a fourth embodiment of the present invention will be described with reference to FIG. In addition, the same parts as those of the above-described embodiments are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, the heater device of the present invention as described above is used in a fixing device of an image forming apparatus such as a printer.

In FIG. 6, reference numeral 1 is a ceramic heater, and the ceramic heater 1 has a longitudinal direction in the transverse direction of the fixing film (direction perpendicular to the running direction of the fixing film 7),
A heater substrate 3, a resistance heating element 2, a temperature detecting means 5,
It is provided with a glass member 4 and is fixedly supported by a horizontally long heater support 20 having rigidity, high heat resistance, and heat insulation.

The resistance heating element 2 is formed by coating an electric resistance material such as Ag / Pd (silver palladium) .Ta ₂ N by screen printing along the substantially central portion of the upper surface of the ceramic heater substrate 3. It is a thing.

The surface thereof is coated with the glass member 4, and like the above-mentioned embodiments,
The contact portion 4a of the temperature detecting means 5 is formed thicker than the other covering portions 4b.

As the temperature detecting means 5, a thermistor having a low heat capacity or the like can be used, and the abutting portion 4a can be used.
Is abutted to the central part of.

In the ceramic heater 1 of this embodiment, the resistance heating element 2 is energized from both ends in the longitudinal direction,
The resistance heating element 2 is made to generate heat over substantially the entire length. The energization is AC 100V, and the energization power is controlled by controlling the phase angle of the energization to the resistance heating element 2 by an energization control circuit (not shown) including a triac according to the temperature detected by the temperature detection means 5.

A driving roller 8 and a driven roller 9 are disposed above the ceramic heater 1 substantially in parallel with the ceramic heater 1, and a heater support 20 and a driving roller for supporting the ceramic heater 1 are provided. An endless belt-shaped fixing film 7, which is a heat-resistant film, is stretched and stretched by a film suspension tension member 8 and a driven roller 9.

The driving roller 8 is rotated clockwise by a driving source (not shown), and the driven roller 9 is fixed to the fixing film 7.
Since the fixing film 7 also serves as a tension roller, the fixing film 7 is unfixed as a heated material conveyed from the image forming section (A) side in a clockwise direction at a predetermined peripheral speed as the driving roller 8 is rotationally driven. It is rotationally driven at the same peripheral speed as the conveying speed of the recording material P carrying the toner image Ta on the upper surface.

The endless belt-shaped fixing film 7 which is rotationally driven in this manner is repeatedly used for heat fixing of the toner image, and therefore has excellent heat resistance, releasability and durability, and is generally used. Is 100 μm or less, preferably 40 μm
Use a thin wall with a thickness of m or less. For example, polyimide, polyether imide, PES, PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin)
Single layer film of heat resistant resin such as, or composite layer film,
For example, it is a film having a thickness of 20 μm and a release coating layer having a thickness of 10 μm formed by adding a conductive material to a fluororesin such as PTFE (tetrafluoroethylene resin) / PAF on at least the image contact surface side.

A pressure roller 10 serving as a pressure member is disposed below the ceramic heater 1. The pressure roller 10 has a rubber elastic layer 12 having a good releasability such as silicone rubber. The heating member 1 having the endless belt-shaped fixing film 7 sandwiching the descending film portion.
Is pressed against the lower surface of the sheet by a biasing means (not shown) with a total pressure of 4 to 12 kgf.
The recording material P is rotated about the cored bar 11 in the counterclockwise direction which is the forward direction of the conveyance direction of the recording material P.

In the fixing device as described above, the image forming unit (A) is operated by the image forming start signal and the unfixed toner image T conveyed from the image forming unit to the fixing device.
The recording material P carrying a on the upper surface is guided by the guide 14 and enters between the fixing film 7 and the pressure roller 10 in the pressure contact portion (fixing nip portion) N between the ceramic heater 1 and the pressure roller 10. , The unfixed toner image surface is in close contact with the lower surface of the fixing film 7 which is rotated in the same direction at the same speed as the conveyance speed of the recording material P in the overlapping state with the fixing film 7 and the heating body 1 and the pressure roller 10. The fixed image Tc is formed by passing between the mutual pressure contact parts N and
Fixing takes place.

At this time, stable and accurate temperature control is performed by the heater device according to the present invention, and a good image can be obtained.

In this embodiment, the heater device described in the second embodiment is used, but the heater device described in other embodiments may be used.

[0051]

As described above, the first embodiment according to the present application is described.
According to the invention of claim 1, the glass member for coating the heater substrate including the resistance heating element is generated from the resistance heating element on the heater substrate, because the thickness of the portion in contact with the temperature detecting means is thicker than other coatings. Accurate temperature detection can be performed by detecting heat from an arbitrary point at substantially equal distances.

According to the second invention of the present application,
Since the portion of the glass member according to the first aspect of the present invention that comes into contact with the temperature detecting means has, for example, a hemispherical shape with the center of the resistance heating element as a reference, the heat generated from the resistance heating element has a hemispherical contacting portion. In this case, the temperature change is transmitted so as to be uniform, and accurate temperature detection can be performed.

Further, in the third invention according to the present application, in the glass member for coating the heater substrate including the resistance heating element in the heater device of the fixing device, the thickness of the portion contacting the temperature detecting means is different from that of the other coating. Since the thickness is thicker than that, accurate temperature detection can be performed by detecting heat from an arbitrary point generated from the resistance heating element on the heater substrate at substantially equal distances, and good fixing can be performed.

According to the fourth invention of the present application,
Since the portion of the glass member according to the third aspect of the invention that comes into contact with the temperature detecting means has a hemispherical shape, for example, with the center of the resistance heating element as a reference, the heat generated from the resistance heating element has a hemispherical contacting portion. In this case, the temperature change is transmitted so as to be uniform, and accurate temperature detection is performed, so that good fixing can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view of a heater device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the heater device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view of the heater device according to the first embodiment of the present invention.

FIG. 4 is a perspective view of a heater device according to a second embodiment of the present invention.

FIG. 5 is a sectional view of a heater device according to a second embodiment of the present invention.

FIG. 6 is a sectional view of a fixing device according to a third embodiment of the present invention.

FIG. 7 is a perspective view of a conventional heater device.

FIG. 8 is a cross-sectional view of a conventional heater device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic heater (heater device) 2 Resistance heating element 3 Heater substrate 4 Glass member 4a Contact part (part which temperature detection means contact) 4b Covering part 5 Temperature detection means 7 Fixing film (heat resistant film) 8,9 Drive roller (Suspended member) P Recording material (heated material) Ta Toner (heated material)

Claims (4)

[Claims] 1. A ceramic heater substrate, a resistance heating element printed on the heater substrate, a glass member covering the heater substrate including the resistance heating element, and a surface of the glass member contacting the heater member. In the heater device provided with the temperature detecting means, the glass member is such that the thickness of a portion of the glass member with which the temperature detecting means abuts is larger than the thickness of other coating portions. apparatus. 2. The heater device according to claim 1, wherein the shape of the portion with which the temperature detecting means is in contact is hemispherical. 3. A ceramic heater substrate, a resistance heating element printed on the heater substrate, a glass member for covering the heater substrate including the resistance heating element, and a surface of the glass member so as to come into contact with each other. And a heater device provided with a temperature detecting means, wherein a heat-resistant film is suspended and stretched on a film suspension tension member including the heater device to drive the film. In the fixing device, the heat energy of the heater device is applied to the material to be heated through the film by bringing the material to be heated into close contact with the surface opposite to the device side and passing through the heater device position. The fixing device, wherein the glass member has a thickness of a portion with which the temperature detecting means is brought into contact with is larger than a thickness of other covering portions. 4. The fixing device according to claim 3, wherein the shape of the portion with which the temperature detecting means is in contact is hemispherical.