JP2537919Y2 - Ceramic heater - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a ceramic heater in which a resistance heating element layer and an electrode layer are formed on a ceramic substrate, more specifically, for example, used as a fixing heater of a copying machine.
The present invention relates to a long ceramic heater whose temperature is controlled by a temperature detector.

[0002]

2. Description of the Related Art Conventionally, as a ceramic heater used for the above-mentioned purpose, for example, there is a ceramic heater in which a resistance heating element layer and an electrode layer are formed on one surface of an alumina substrate. Since the heating is small and the direct heating is performed by integrating the resistance heating element layer and the ceramic substrate, the rise time of the surface temperature becomes very fast, and the temperature fluctuation of the heater due to the change of the applied voltage becomes large. Therefore, accurate and quick temperature detection is required for controlling the temperature of the heater.

[0003] In response to this request, the present applicant has filed Japanese Utility Model Application
-99338 eliminates the drawbacks such as the deviation of the detection temperature and the delay of the response time caused by the large heat capacity of the temperature detector, and the temperature detection element and the ceramic which becomes a problem in performing more accurate temperature control. Provided is a ceramic heater for preventing generation of a gap or the like between heaters.

[0004] The ceramic heater disclosed in Japanese Utility Model Application No. 2-99338, for example, prints and fires a resistance heating element layer and an electrode layer on a ceramic substrate having a length of 270 mm x a width of 70 mm x a thickness of 1 mm. The thermistor has a structure in which a thermistor is fixed to the center of the surface opposite to the heating element layer with an adhesive.
As a result, it is possible to prevent a temperature difference between the surface temperature of the heater and the detected temperature, a delay in response time, and an inaccurate temperature detection due to the generation of a gap, thereby achieving good thermal response and accurate temperature control.

An example of this structure will be described below with reference to FIG. First, a ceramic substrate 10 made of alumina is used.
The resistance heating element layer 11 is formed on the upper surface of the substrate, and the electrode layers 12 are formed at the electrode extraction portions at both upper ends of the resistance heating element layer 11. Then, a glass-sealed thermistor 13 is bonded with an inorganic adhesive 14 to the center of the surface opposite to the surface on which the resistance heating element layer 11 and the electrode layer 12 are formed. At this time, if the thermistor lead is connected directly to the lead wire to the temperature control circuit, the mechanical shock applied to the lead wire will directly apply to the thermistor lead and damage the thermistor. Further, it is preferable to electrically connect the relay component to a lead wire of the temperature control circuit.

As the relay part, for example, a metal pin 23 is erected on a holder 21 as shown in FIG. The use example of the relay component will be specifically described. First, the thermistor lead 22 of the thermistor 13 for detecting the temperature of the ceramic heater 20 is connected to the metal pin 23 of the holder 21 fixed to the ceramic heater by solder 24.
Further, the metal pin 23 is connected to the lead wire 25 for the temperature control circuit.
Are connected by spot welding.

[0007]

[Problems to be Solved by the Invention] However, since such a relay part is used, complicated operations such as solder connection of the thermistor lead and spot welding connection of the lead wire to the temperature control circuit are required, and the production cost is reduced. Has led to a rise.

[0008] By soldering the thermistor lead to two metal pins having a smaller diameter, caulking a metal terminal for spot welding a lead wire to a temperature control circuit, and spot welding the terminal to the metal pin, etc. Problems such as dropping or cutting of the thermistor leads and breaking of metal pins have occurred.

In the temperature detection capability, the thermistor lead and the metal pin have heat capacity and also have a heat radiation effect, so that the temperature detection shift and the response time delay are slightly generated.

The present invention simplifies a relay mechanism for electrically connecting a thermistor to a temperature control circuit, reduces costs and improves quality by reducing the number of parts and the number of work steps, and further improves the temperature detection capability. An object of the present invention is to provide an intended ceramic heater.

[0011]

According to the present invention, there is provided a ceramic heater having a resistance heating element layer and an electrode layer formed on one surface of a ceramic substrate. The glass-sealed thermistor is fixed by an adhesive, and the thermistor lead of the thermistor is connected to a conductive layer provided on a ceramic substrate.

[0012]

In the ceramic heater according to the present invention, since a conductive layer is printed on the surface of the ceramic substrate to which the thermistor is fixed, relay parts such as metal pins and lead wires are unnecessary, and the process of mounting these parts becomes unnecessary. Work content is simplified.

Further, by forming the conductive layer on both ends of the ceramic substrate, it is possible to simultaneously take out the electrodes for the heater and the electrodes for the sensors at both ends of the ceramic substrate, thereby facilitating connection to the control circuit. Structure.

In addition, the relay part is unnecessary and the thermistor lead is shortened, so that the heat capacity is reduced. In addition, since the conductive layer is formed thin by printing and integrated with the heating section, heat radiation is small, and high-speed and accurate temperature detection is performed. Can be.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the drawings. FIG. 1 is a front view showing an embodiment of a ceramic heater according to the present invention. The ceramic heater 1 includes a ceramic substrate 2 made of alumina, a resistance heating element layer 3, an electrode layer 4, an overcoat layer (not shown), a glass-sealed thermistor 5, an inorganic adhesive 6, and a conductive layer 7. You.

In manufacturing the ceramic heater 1 ,
First, a paste for a resistance heating element was applied on one side of a ceramic substrate 2 having a length of 270 mm, a width of 7 mm and a thickness of 1 mm to a width of 1.5 m.
After printing at 210 m in length and 210 mm in length, it was baked in an electric furnace at 800 ° C. for 10 minutes to form a resistance heating element layer 3 having a resistance value of about 30Ω. Next, an electrode paste was printed on electrode extraction portions on both ends of the resistance heating element layer 3, and then fired in an electric furnace at 800 ° C. for 10 minutes to form an electrode layer 4. After printing the overcoat paste on the upper part of these two layers,
It was baked in an electric furnace for 10 minutes to form an overcoat layer.

The conductor paste is printed at a temperature of 800 ° C. after printing the conductor paste in a shape having a width of 2 mm and a length of 100 mm in the longitudinal direction, respectively, from both ends of the surface opposite to the surface on which these three layers are formed so as not to conduct each other. The conductive layer 7 was formed by firing in an electric furnace for 10 minutes.

Next, in the center of the surface on which the conductive layer 7 is formed, a glass-sealed thermistor 5 having a diameter of a glass portion of about 1 mm.
(B = 3000-5000) is bonded with an inorganic adhesive 6 (Toa Gosei Chemical Co., trade name: Aron Ceramic) having high heat resistance and high adhesive strength, and after 10 hours of air drying, 90 ° C. in a dryer. × 1 hour, fixed at 150 ° C. × 1 hour. Then, the thermistor lead 9 of the thermistor 5 was connected to the conductive layer 7 with a conductive paste 8.

The ceramic heater having the glass-sealed thermistor thus formed can transmit an electric signal from the thermistor to the temperature control circuit without using a relay component as conventionally used.

[0020]

As described above, according to the present invention, a resistance heating element layer, an electrode layer, and an overcoat layer are formed by printing on a ceramic substrate, and a conductive layer is formed by printing on a surface opposite to the three layers. In addition, by connecting the thermistor lead and the conductive layer electrically by fixing the thermistor with an adhesive, relay parts such as metal pins and lead wires become unnecessary, which simplifies the work and leads to cost reduction. . In addition, since the relay parts are no longer required, there is no possibility that the quality is degraded due to breakage of each part.

Further, by forming the conductive layer up to both ends of the ceramic substrate, the sensor electrodes can be taken out at both ends of the ceramic substrate in the same manner as the heater electrodes, and the connection to the temperature control circuit becomes easy.

In the temperature detection capability, the heat capacity of the thermistor lead and the conductive layer is small, and the heat radiation is also small.
High-speed and accurate temperature detection becomes possible.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a ceramic heater according to the present invention.

FIG. 2 is a front view showing an example of a conventional ceramic heater.

FIG. 3 is a partially cutaway sectional view showing a state in which a relay component is attached to the ceramic heater of FIG. 2;

[Description of Signs] 1 ceramic heater 2 ceramic substrate 3 resistance heating element layer 4 electrode layer 5 glass-sealed thermistor 6 inorganic adhesive 7 conductive layer 8 conductive paste 9 thermistor lead 10 ceramic substrate 11 resistance heating element layer 12 electrode layer 13 Glass-sealed thermistor 14 Inorganic adhesive 20 Ceramic heater 21 Holder 22 Thermistor lead 23 Metal pin 24 Solder 25 Lead wire 26 Terminal

Claims (1)

(57) [Scope of request for utility model registration] 1. A ceramic heater in which a resistance heating element layer and an electrode layer are formed on one surface of a ceramic substrate, and a glass-sealed thermistor is fixed on another surface of the ceramic substrate with an adhesive, and the thermistor of the thermistor is provided. A ceramic heater characterized in that leads are connected to a conductive layer provided on a ceramic substrate.