JP4536887B2 - Heating element, fixing device using the same, and method of manufacturing heating element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a heating element provided in a fixing device such as a printer.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a printer or the like is provided with a fixing device for fixing toner on a sheet by heat, and this fixing device is provided with a heating element for supplying heat. FIG. 3 is a schematic cross-sectional view showing an example of the heating element. The heating element includes, for example, a substrate 1 made of aluminum nitride ceramics, a resistor 2 made of, for example, silver / palladium formed on the substrate 1 in a thick film shape, and the resistor 2 to protect it. The crystallized glass layer 3 thus formed and the amorphous glass layer 4 having insulating properties and smoothness formed on the upper surface of the crystallized glass layer 3 are roughly constituted. Although not shown in FIG. 3, an electrode layer for supplying power to the resistor 2 is formed on the substrate 1.
[0003]
In the heating element having such a configuration, when electric power is supplied to the resistor 2 through an electrode layer (not shown), the resistor 2 generates heat with a predetermined heat generation amount. In this heating element, since aluminum nitride ceramics having excellent thermal response is used as the substrate material, heat spreads over the entire substrate. Therefore, the entire substrate can be used as a heating element in a fixing device such as a printer. For example, an alumina-based ceramic substrate used for a thermal print head, for example, generates heat only at the portion of the heating resistor, and the substrate may crack due to poor heat distribution. However, the heating element has an advantage that the substrate is not easily cracked because heat spreads over the entire substrate.
[0004]
[Problems to be solved by the invention]
On the other hand, in the heating element, since the aluminum nitride ceramic is used for the substrate 1, the following inconvenience occurs. That is, in this heating element, the amorphous glass layer 4 is formed as the uppermost layer. When the glass paste as the material of the amorphous glass layer 4 is printed and fired on the substrate 1, oxygen in the glass is formed. May react and foam. And in this foaming part, a water | moisture content becomes easy to pass, for example, an appropriate layer is not formed, and the amorphous glass layer 4 will impair the insulation.
[0005]
Therefore, normally, as shown in FIG. 3, a crystallized glass layer 3 is interposed between the amorphous glass layer 4 and the substrate 1 so as to prevent such foaming, and these are viewed in a plan view. It is formed so as to overlap almost the same size. In this way, the amorphous glass layer 4 does not contact the substrate 1 and can maintain its insulating properties.
[0006]
However, when the amorphous glass layer 4 and the crystallized glass layer 3 are formed in substantially the same size in plan view, the side surface 3a portion of the crystallized glass layer 3 is exposed to the outside. In the crystallized glass layer 3, if there is a portion exposed to the outside, moisture may invade from the exposed portion, and the crystallized glass layer 3 is generally porous, so that moisture gradually enters the crystallized glass layer 3. There is a case where it penetrates and reaches the resistor 2. If it does so, the whole crystallized glass layer 3 will be in a conduction | electrical_connection state, a proof pressure may fall, and it may become a cause of destruction. In particular, as shown in FIG. 4, when printing misalignment occurs during printing of the amorphous glass layer 4, the exposed portion also spreads on the upper surface 3 b of the crystallized glass layer 3, and moisture is absorbed by the crystallized glass layer 3. Is likely to be.
[0007]
DISCLOSURE OF THE INVENTION
The present invention has been conceived under the circumstances described above, and it is intended to provide a heating element that can prevent moisture from entering from the outside and maintain good insulation. Let that be the issue.
[0008]
In order to solve the above problems, the present invention takes the following technical means.
[0009]
According to the heating element to a first aspect of the present invention, the substrate ing from aluminum nitride-based ceramic, a resistor formed on the substrate, which is formed so as to cover the resistor crystals a glass layer, and the exuded portion formed around the crystallized glass layer on the substrate by glass paste of the crystallized glass layer is printed and baked, the crystallized glass of the above crystallized glass layer They cover it so as not to layer is exposed to the outside, and the peripheral portion is characterized by comprising, an amorphous glass layer formed in contact with the exudate unit.
[0010]
According to the configuration of the present invention, since the amorphous glass layer formed on the upper surface of the crystallized glass layer is formed so as to cover the crystallized glass layer, the crystallized glass layer is not exposed to the outside. . Therefore, in the crystallized glass layer, it is possible to prevent moisture from entering from the outside, and it is possible to suppress a decrease in pressure resistance in the crystallized glass layer.
[0012]
Furthermore , as described in the section of the prior art, in this heating element, when the glass paste of the amorphous glass layer is printed and fired on the substrate, it may react with oxygen in the glass and foam. The insulating properties of the amorphous glass layer may be impaired. However, when the glass paste used as the material of the crystallized glass layer is printed and fired on the substrate, the glass paste at the time of firing oozes out on the substrate around the printed and fired region, and an exuded portion is formed. This exudation portion has a thin film-like region formed on the substrate. In the present invention, this exudation portion is used, that is, the peripheral portion of the amorphous glass layer is formed on the exudation portion. To. If it does in this way, it can prevent that the glass paste of an amorphous glass layer is printed and baked on a board | substrate, and it will be suppressed that the insulation property of an amorphous glass layer is impaired.
[0013]
The fixing device provided by the second aspect of the present invention is characterized by using the heating element provided by the first aspect of the present invention. Thus, for example, a highly reliable fixing device can be obtained by using a heating element that maintains good insulation as described above for a fixing device that is provided in a printer or the like and that fixes toner on paper by heat. Can be provided.
[0014]
In addition, according to the method for manufacturing a heating element provided by the third aspect of the present invention, a step of forming a resistor on a substrate made of an aluminum nitride ceramic , and a glass paste so as to cover the resistor A step of forming a crystallized glass layer by printing and baking so that an exudation part is formed around the crystallized glass layer on the substrate, and the crystallized glass layer is formed on the crystallized glass layer. And a step of forming an amorphous glass layer so as to cover it so as not to be exposed to the outside and so that a peripheral portion is in contact with the exudation portion .
[0015]
According to the method for manufacturing a heating element according to the third aspect of the present invention, the heating element provided by the first aspect of the present invention can be manufactured, and the effects obtained by the first aspect can be obtained. The same effect can be obtained.
[0016]
Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings.
[0018]
FIG. 1 is a schematic cross-sectional view showing an example of a heating element according to the present invention. This heating element is provided in a fixing device provided in a printer or the like for fixing toner onto a sheet by heat, and supplies heat to the sheet. The heating element includes a substantially flat substrate 1 made of, for example, an aluminum nitride ceramic. Aluminum nitride ceramics are excellent in thermal responsiveness, so that heat can be spread over the entire substrate 1. For this reason, this heating element has an advantage that it is possible to suppress the occurrence of substrate cracking that may occur in comparison with alumina-based ceramics or the like having poor heat distribution.
[0019]
A resistor 2 made of, for example, silver / palladium is formed on the substrate 1 so as to extend in a direction perpendicular to the paper surface in FIG. The resistor 2 has a predetermined width and is formed in a thick film shape. Although omitted in FIG. 1, an electrode layer for supplying power to the resistor 2 is formed on the substrate 1. When electric power is supplied to the electrode layer from a driving device (not shown), the resistor 2 generates heat with a predetermined heat generation amount. And in this heat generating body, since the aluminum nitride ceramics excellent in thermal responsiveness are used for the board | substrate 1, heat spreads to the board | substrate 1 whole. Therefore, if this heating element is used in a fixing device such as a printer, for example, the toner can be satisfactorily fixed on the paper surface using the entire substrate 1.
[0020]
On the upper surface of the resistor 2, the crystallized glass layer 3 is formed to have a predetermined area with respect to the substrate 1 so as to cover the upper surface of the resistor 2. The crystallized glass layer 3 is formed by printing and baking a glass paste which is a material of this layer. The crystallized glass layer 3 is formed for the purpose of preventing foaming in the amorphous glass layer 4 described later. That is, the amorphous glass layer 4 is formed for the purpose of protecting the resistor 2, but when printed and fired on the substrate 1, it may react with oxygen in the glass and foam. In some cases, moisture penetrates from the foamed portion and impairs its insulating properties. Therefore, the crystallized glass layer 3 is formed to be interposed between the amorphous glass layer 4 and the substrate 1 so as to prevent the amorphous glass layer 4 from foaming.
[0021]
An amorphous glass layer 4 is laminated on the crystallized glass layer 3. The amorphous glass layer 4 is made of, for example, a Pb—Si—B—Al—Ca—Ba—Mg system and has insulating properties and smoothness. The amorphous glass layer 4 is formed by printing and baking a glass paste which is a material of this layer.
[0022]
The amorphous glass layer 4 is formed so as to cover all of the upper surface 3b and the side surfaces 3a of the crystallized glass layer 3, that is, the crystallized glass layer 3 is not exposed to the outside. As a result, since moisture does not enter the crystallized glass layer 3 from the outside, as described in the section of the prior art, moisture enters from the part exposed to the outside, and the entire crystallized glass layer 3 becomes conductive. It can be prevented by the configuration according to the present embodiment that it breaks into a state. Accordingly, it is possible to prevent a decrease in pressure resistance in the crystallized glass layer 3, and to provide a highly reliable heating element and a fixing device including the heating element.
[0023]
Incidentally, as described above, when the amorphous glass layer 4 is formed so as to cover the crystallized glass layer 3, the peripheral edge 4 a of the amorphous glass layer 4 comes into contact with the substrate 1. When the amorphous glass layer 4 is in contact with the substrate 1, there arises a problem that the amorphous glass layer 4 is foamed as described above. Therefore, in the present embodiment, as a countermeasure, foaming of the amorphous glass layer 4 is prevented by the following method.
[0024]
That is, when the glass paste used as the material of the crystallized glass layer 3 is printed and fired on the substrate 1 made of aluminum nitride ceramics, as shown in FIG. 2, the area around the substrate 1 on which the glass paste is printed and fired is formed. In addition, the exuded portion 5 is formed in which the glass paste at the time of firing exudes onto the substrate 1. That is, the exuding part 5 is formed in a thin film shape spreading on the substrate 1, and the width L of the exuding part 5 is about 0.5 to 0.9 mm toward the outside.
[0025]
When the amorphous glass layer 4 is formed, the peripheral edge 4 a of the amorphous glass layer 4 is formed on the exuded portion 5. That is, the peripheral edge portion 4 a of the amorphous glass layer 4 is formed so as not to extend outside the width L of the exudation portion 5, in other words, not in contact with the substrate 1. Thus, by utilizing the exuded portion 5 formed when the glass paste of the crystallized glass layer 3 is printed and fired, the amorphous glass layer 4 can be prevented from coming into direct contact with the substrate 1. The insulating property of the amorphous glass layer 4 can be maintained well.
[0026]
The width L of the exuded portion 5 is not limited to the above-described value. For example, when the glass paste of the amorphous glass layer 4 is printed and fired in the same manner as the glass paste of the crystallized glass layer 3, In consideration of oozing on 1, it may be formed slightly longer.
[0027]
Next, the manufacturing method of this heat generating body is demonstrated. First, an aluminum nitride ceramic material is formed into a green sheet by, for example, extrusion molding. Then, after firing, the substrate 1 is formed by cutting into a predetermined shape.
[0028]
Next, a strip-shaped resistor 2 is formed on the substrate 1. That is, a resistor paste 2 is formed by applying a silver / palladium resistor paste to a predetermined position on the substrate 1 in a band shape, then drying for a predetermined time and baking at a predetermined baking temperature.
[0029]
Subsequently, a glass paste as a material for the crystallized glass layer 3 is printed on the substrate 1 so as to cover the resistor 2, dried, and fired at a predetermined firing temperature. Form. In this case, on the substrate 1, around the region where the glass paste of the crystallized glass layer 3 is printed and baked, the glass paste at the time of baking oozes out on the surface of the substrate 1 to form an exuded portion 5 ( (See FIG. 2).
[0030]
Then, the amorphous glass layer 4 is formed so as to cover the upper surface 3b and the side surface 3a of the crystallized glass layer 3, that is, so as not to expose the crystallized glass layer 3 to the outside. That is, the glass paste used as the material of the amorphous glass layer 4 is printed, then dried, and fired at a predetermined firing temperature to form the amorphous glass layer 4.
[0031]
Here, when the glass paste of the amorphous glass layer 4 is printed and fired on the surface of the substrate 1 made of an aluminum nitride ceramic, foaming occurs in the amorphous glass layer 4, and the amorphous glass layer 4 is appropriate. No longer formed. However, as described above, since the exuded portion 5 is formed around the crystallized glass layer 3 where the glass paste is printed and fired, the glass paste for the amorphous glass layer 4 is placed on the exuded portion 5. The amorphous glass layer 4 is formed by printing. Due to the exuded portion 5, the amorphous glass layer 4 is not brought into contact with the surface of the substrate 1, the occurrence of foaming is suppressed, and the amorphous glass layer 4 is appropriately formed.
[0032]
Of course, the scope of the present invention is not limited to the embodiment described above. For example, the present invention may be applied not only to a fixing device such as a printer but also to other electronic components such as a thermal print head. The materials, shapes, etc., of the substrate 1, resistor 2, crystallized glass layer 3, and amorphous glass layer 4 are not limited to those described above.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a main part of a heating element according to the present invention.
2 is a detailed cross-sectional view of a main part of the heating element shown in FIG.
FIG. 3 is a cross-sectional view of a main part of a conventional heating element.
FIG. 4 is a cross-sectional view of a main part of a conventional heating element when printing misalignment occurs.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Substrate 2 Resistor 3 Crystallized glass layer 4 Amorphous glass layer 4a Peripheral part 5 Exuded part

Claims (3)

A substrate ing from aluminum nitride-based ceramics,
A resistor formed on said substrate,
And the formed crystallized glass layer so as to cover the resistor,
An exuded portion formed around the crystallized glass layer on the substrate by printing and baking the glass paste of the crystallized glass layer;
An amorphous glass layer formed on the crystallized glass layer so as to cover the crystallized glass layer so that the crystallized glass layer is not exposed to the outside, and so that a peripheral part is in contact with the exuded part ;
A heating element, comprising: A fixing device using the heating element according to claim 1 . Forming a resistor on a substrate made of an aluminum nitride ceramic ,
Forming a crystallized glass layer so as to form an exudation part around the crystallized glass layer on the substrate by printing and baking a glass paste so as to cover the resistor;
Covering the crystallized glass layer on the crystallized glass layer so that the crystallized glass layer is not exposed to the outside, and forming an amorphous glass layer so that the peripheral part is in contact with the exuded part;
The manufacturing method of the heat generating body characterized by including.

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