JP2008159502A - Heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heater in which a temperature resistance coefficient of a heating resistor can be made smaller. <P>SOLUTION: The heater A is equipped with a substrate 1 and the heating resistor 2 formed on the substrate 1. The heating resistor 2 contains Ag-Pd and glass, and when the weight ratio of the glass in the heating resistor is made x, the weight ratio y of Pd in the Ag-Pd is made to satisfy an expression of -0.091x+0.50≤y≤-0.091x+0.57. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heater used as means for heating a recording sheet in order to thermally fix toner transferred to the recording sheet in a laser printer, for example.

  This type of heater includes, for example, a substrate and a heating resistor. The substrate has, for example, a long rectangular shape and is made of an insulating material. The heating resistor includes, for example, Ag—Pd and is formed in a strip shape on the substrate. The heating resistor is covered with, for example, a glass protective film. This heater is used to heat-fix the toner on the recording paper. When the heating resistor is supplied with power from an AC power source, the heating resistor generates heat. When the recording paper onto which the toner has been transferred is pressed against the heater in a heat generating state by the platen roller, the toner is fixed to the recording paper.

  However, the resistance value of the heating resistor containing Ag-Pd varies with temperature. The magnitude of the temperature dependence of the resistance value is generally represented by a thermal coefficient of resistance (TCR) which is a rate of change in resistance value per 1 ° C. For example, the resistance temperature coefficient of a conventional heater is about 300 ppm / ° C. The larger the resistance temperature coefficient, the more difficult the current control for keeping the heating resistor of the heater at a constant temperature. When the temperature of the heating resistor varies, it is impeded that the toner is appropriately heat-fixed on the recording paper. In recent years, there has been a strong demand for improving the printing speed of laser printers and increasing the definition of printing, and it has been desired to further reduce the resistance temperature coefficient of the heating resistor.

JP 2004-6289 A

  The present invention has been conceived under the above circumstances, and an object thereof is to provide a heater capable of reducing the temperature resistance coefficient of a heating resistor.

  The heater provided by the present invention is a heater including a substrate and a heating resistor formed on the substrate, and the heating resistor includes Ag-Pd and glass, and the heating resistor. When the weight ratio of the glass in the body is x, the weight ratio y of Pd in the Ag-Pd is -0.091x + 0.50 ≦ y ≦ −0.091x + 0.57. Yes.

  According to such a configuration, the resistance temperature coefficient of the heating resistor can be set to a very small value of 100 ppm / ° C. or less. Thereby, it becomes easy to control the heating resistor to a constant temperature. Therefore, it is possible to stably heat-fix the toner on the recording paper by the heater, and it is possible to improve the printing speed of the laser printer and increase the printing precision.

  In a preferred embodiment of the present invention, the weight ratio of the glass in the heating resistor is 3 to 25%. By blending the glass in such a ratio, it is possible to prevent the glass as an insulator from unduly hindering the conduction of the heating resistor while increasing the bonding force between the heating resistor and the substrate. it can.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

  1 and 2 show an example of a heater according to the present invention. The heater A of this embodiment includes a substrate 1, a heating resistor 2, and a protective film 3. The heater A is used, for example, to thermally fix the toner transferred to the recording paper P in a laser printer. For example, the recording paper P is slid with respect to the heater A by being pressed against the heater A by the rotating platen roller R. As a result, the toner transferred onto the recording paper P is heated and fixed on the recording paper P. In FIG. 1, the protective film 3 is omitted for convenience of understanding.

The substrate 1 has a long rectangular shape and is made of an insulating material. Examples of the insulating material include AlN and Al ₂ O ₃ . The substrate 1 is formed by firing a substrate material containing, for example, AlN or Al ₂ O ₃ .

  The heating resistor 2 is formed on the substrate 1 and has a U-shaped band shape. The heating resistor 2 includes a resistor material and crystallized glass. The resistor material is Ag-Pd. The weight ratio y of Pd in this Ag—Pd is set to −0.091x + 0.50 ≦ y ≦ −0.091x + 0.57. x is the weight ratio of the crystallized glass in the heating resistor 2. For example, when the weight ratio x of the crystallized glass is 10%, the weight ratio y of Pd is 49 to 56%.

The proportion of the crystallized glass in the heating resistor 2 is preferably 3 to 25%. As the crystallized glass, SiO ₂ —B ₂ O ₃ —R, or SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —R (R is any one of ZnO ₂ , Li ₂ O ₃ and TiO ₂ ). Is preferably used. In the present embodiment, SiO ₂ —B ₂ O ₃ —ZnO ₂ is used. In this case, the crystallized glass has a softening point temperature of about 570 ° C. and a crystallization temperature of about 730 ° C. The crystallized glass is contained for the purpose of increasing the bonding force between the heating resistor 2 and the substrate 1 and can prevent the heating resistor 2 from peeling off.

The heating resistor 2 is formed by applying a resistor paste containing Ag—Pd and the crystallized glass including SiO ₂ —B ₂ O ₃ —ZnO ₂ to the substrate 1 and then baking it. In this firing, the firing temperature is gradually raised from about room temperature to about 850 ° C. and then held at 850 ° C. for a certain time. That is, baking is performed at a baking temperature that is 100 ° C. or higher than the crystallization temperature of the crystallized glass.

  The protective film 3 is for protecting the heating resistor 2 and is made of, for example, crystallized glass or amorphous glass. The protective film 3 is formed, for example, by applying a glass paste so as to cover the heating resistor 2 and then baking it.

  Next, the operation of the heater A will be described.

  The inventors have studied the material of the heating resistor 2 for the purpose of dramatically reducing the temperature coefficient of resistance α, which has been about 300 ppm / ° C. in the past. FIG. 3 is an example of the result, and shows the relationship between the weight ratio y of Pd in Ag—Pd and the resistance temperature coefficient α of the heating resistor 2 in which the weight ratio y is varied. The weight ratio x of the crystallized glass in these heating resistors 2 is all 10%. As clearly shown in the figure, the temperature coefficient of resistance α greatly depends on the weight ratio y of Pd.

  When Ag-Pd is used industrially as a general material of the heating resistor 2, it is directed to lower the weight ratio y of Pd. This is because Pd is significantly more expensive than Ag. Conventionally used heaters have a resistance temperature coefficient α of about 300 ppm / ° C. In order to achieve such a temperature coefficient of resistance α, the weight ratio y of Pd may be about 25 to 40%. Further, from the viewpoint of reducing the manufacturing cost of the heater, the weight ratio y of Pd employed is converged to about 25%.

  However, the inventors conducted an experiment in which the weight ratio y of Pd was changed to about 80%, which was a range not conventionally employed, for the purpose of further reducing the temperature coefficient of resistance α. As a result, it was found that when the weight ratio y exceeds 45%, the temperature coefficient of resistance α rapidly decreases. It was also found that the resistance temperature coefficient α takes the minimum value when the weight ratio y is about 52 to 53%, and increases in a region where the weight ratio y is larger than this. Therefore, the temperature coefficient of resistance α is reduced to at least 100 ppm / ° C. or less, specifically about 80 ppm / ° C. by setting the weight ratio y of Pd to 49 to 56%, which has not been conventionally adopted. I was able to. Since the temperature coefficient α of the heat generating resistor 2 is remarkably as small as 1/3 or less of the conventional temperature, the temperature control of the heat generating resistor 2 can be performed more accurately. As described above, according to the heater A, it is possible to stably heat-fix the toner on the recording paper P, and it is possible to improve the printing speed of the laser printer and increase the definition of printing.

Further, the inventors clearly show that the numerical range of the weight ratio y of Pd for suppressing the resistor α to 100 ppm / ° C. or less varies depending on the weight ratio x of the crystallized glass contained in the heating resistor 2. I made it. That is, the relationship between the weight ratio y of Pd and the resistance temperature coefficient α is represented by the graph shown in FIG. However, it has been found that when the weight ratio x of the crystallized glass changes, the graph shown in FIG. 3 slightly shifts. Therefore, the inventors conducted an experiment in the case where the weight ratio x of the crystallized glass in the heating resistor 2 was changed to 3%, 14%, and 25%. Based on this experiment, the maximum value y _max and the minimum value y _min of the weight ratio y of Pd capable of setting the resistor temperature coefficient α to 100 ppm / ° C. or less are shown in FIG. As shown in the figure, the weight ratios y _max and y _min of Pd were found to decrease monotonously with respect to the weight ratio x of the crystallized glass. From the above results, when the weight ratio y of Pd is −0.091x + 0.50 ≦ y ≦ −0.091x + 0.57, the resistance temperature coefficient α of the heating resistor 2 can be set to 100 ppm / ° C. or less. .

  If the ratio of the crystallized glass in the heat generating resistor 2 is 3% or more, the crystallized glass has an effect of firmly bonding the heat generating resistor 2 to the substrate 1. Moreover, if the ratio of the crystallized glass is 25% or less, the crystallized glass that is an insulator does not have a risk of unduly hindering the conduction of the heating resistor 2.

  The heater according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the heater according to the present invention can be varied in design in various ways.

  As the glass referred to in the present invention, it is advantageous to use crystallized glass for preventing exfoliation of the heating resistor, but the present invention is not limited to this, and amorphous glass may be used.

It is a perspective view which shows an example of the heater which concerns on this invention. It is sectional drawing which follows the II-II line | wire of FIG. It is a graph which shows the relationship between resistance temperature coefficient (alpha) and Pd weight ratio y. It is a graph which shows the relationship between Pd weight ratio ymax and ymin and glass weight ratio x.

Explanation of symbols

A Heater P Recording paper R Platen roller x Glass weight ratio y Pd weight ratio 1 Substrate 2 Heating resistor 3 Protective film

Claims (2)

A substrate,
A heating resistor formed on the substrate;
A heater comprising:
The heating resistor includes Ag-Pd and glass,
When the weight ratio of the glass in the heating resistor is x, the weight ratio y of Pd in the Ag-Pd is -0.091x + 0.50 ≦ y ≦ −0.091x + 0.57. Features a heater.   The heater according to claim 1, wherein a weight ratio of the glass in the heating resistor is 3 to 25%.

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