JPS59136767A - Manufacture of cylindrical heating element of constant temperature - Google Patents

Abstract

PURPOSE:To obtain a titled heating element which has a fast temperature rising speed, superior temperature stability, and excellent toner fixability by providing plural recessed grooves on the internal wall side of a cylindrical metallic body and adhering thermistors with positive characteristics in those recessed grooves. CONSTITUTION:The positive-characteristic thermistors 7 (6: common electrode) are arranged with adhesives in said recessed grooves of the cylindrical metallic body 5 which is cylindrical outwardly and has the plural recessed grooves tapered at edge parts. Then, a presser 8 made of a rubber bag with heat resistance and elasticity is put in the cavity part of the cylindrical metallic body 5, and while the thermistors 7 are pressed in the internal wall of the cylindrical metallic body 5 by pressing air, water 9, etc., into the presser 8 and expanding the presser 8, the adhesives are cured by being heated to adhere the thermistors 7 in the cylindrical metallic body 5; and then the presser 8 is removed to obtain the heating body.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method of manufacturing a cylindrical constant temperature heating element, which is used for constant toner use in copying machines, facsimile machines, etc., among other constant temperature heating elements. .

Conventional structure and problems Conventionally, heaters used for constant toner use in copiers and facsimile machines include infrared lamps, halogen lamps,
Xenon lamp, sheathed heater.

Nichrome wire heaters are known. Its structure is the first
As shown in the figure, a rod-shaped heater (
For example, an infrared lamp, a halogen lamp, a xenon lamp, a sheathed heater, a nichrome wire heater, etc.) 2 are disposed, and a temperature sensor 3 installed near the external surface of the heat dissipation roller 1 detects the surface temperature of the heat dissipation roller 1. Based on this detected temperature, the voltage or current applied to the rod-shaped heater 2 is controlled via the temperature control circuit 4 so that the surface temperature of the heat radiation roller 1 approaches a predetermined temperature.

However, in this kind of toner fixing heater, the heater 2 itself has a large heat capacity, and the heating speed of the heater surface is slow because it does not heat indirectly through an air layer, so it does not reach the temperature that can be copied after turning on the power. It takes a considerable amount of time to wait.

However, temperature control by the temperature sensor 3 does not allow for changes in the surface temperature of the heat dissipation roller 1 due to rapid heat dissipation, for example, when a copy sheet comes into contact with the heat dissipation roller 1.

On the other hand, the quick response is poor and the temperature is unstable, which tends to cause poor toner adhesion. Furthermore, since the heat dissipation roller 1, the rod-shaped heater 2, the temperature sensor 3, and the temperature control circuit 4 are required, the configuration is complicated and therefore expensive and large.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of the conventional toner constant wear heater as described above, has a fast heating rate, short waiting time until it reaches a temperature that can be copied, has good temperature stability, and eliminates toner fixation unevenness. It is an object of the present invention to provide a method for manufacturing a cylindrical constant-temperature heating element used as a toner constant-wear heater, which is easy to manufacture, extensible, inexpensive, and small in size and free from heat generation.

Structure of the Invention Therefore, in the method for manufacturing a cylindrical constant temperature heating element of the present invention, the groove portion of a cylindrical metal body having a circular outer shape and having a plurality of concave grooves each having a tapered edge cut into the inner periphery. , a positive temperature coefficient thermistor having electrodes on a surface in contact with the cylindrical metal body and a surface facing the cylindrical metal body, and a common electrode formed on the electrode on the opposite surface side is disposed through an adhesive, and the cylindrical metal body The positive temperature coefficient thermistor is pressed with uniform force from the inside to the outside in the hollow part of the body, and then the adhesive is heated and cured to integrate it.

This configuration has the following advantages.

■ By placing a positive temperature coefficient thermistor directly on a cylindrical metal body via adhesive, the cylindrical metal body is directly heated, which has much better thermal efficiency than conventional heating through an air layer. Since the temperature rise rate of the external surface of the cylindrical metal body is faster, the waiting time from turning on the power until the temperature reaches the point at which copying can be made can be shortened.

■ By using a positive temperature coefficient thermistor as a heat source,
The self-control function of the positive temperature coefficient thermistor automatically controls the temperature to a constant temperature, making it unnecessary to use a temperature sensor as in the past. The structure is simple, highly safe, inexpensive, and compact.

■ The heat generation efficiency of a cylindrical constant temperature heating element is determined by how much heat generated from the PTC thermistor can be transferred to the cylindrical metal body. By curing the adhesive while applying pressure, the heat generated from the PTC thermistor can be evenly transmitted and the thermal resistance can be small, so a cylindrical constant temperature heating element with good thermal efficiency can be constructed.

■ Furthermore, when placing a positive temperature coefficient thermistor on a cylindrical metal body, by applying even pressure from the inside of the cylindrical metal body to the outside, a large number of elements can be placed on multiple surfaces simultaneously and uniformly. It is easy to manufacture, and the characteristics can be made uniform.

■ By creating a tapered cut on the edge of the concave groove on the inner periphery of the cylindrical metal body, the creepage distance and spatial distance between the electrode provided on one side of the PTC thermistor and the cylindrical metal body can be increased. Therefore, electrical reliability can be improved.

■ Also, by providing a tapered cut,
Since the volume of the metal is reduced by the amount of the cut, the heat capacity becomes smaller and the temperature increase characteristics are further improved.

Description of examples EXAMPLES The present invention will be described in detail below using examples.

FIG. 2, FIG. 3A, and FIG. 3B are diagrams showing a cross section of a cylindrical constant temperature heating element in an embodiment of the present invention and a method of manufacturing the same.

The cylindrical metal body 5 is made of a metal such as aluminum and has a circular outer periphery and a plurality of concave grooves (four in the embodiment) each having a tapered edge cut into the inner periphery. A positive temperature coefficient thermistor having electrodes (not shown) made of a conductive material such as silver on the surface in contact with the shaped metal body 5 and the opposite surface, and a common electrode 6 formed on the electrode on the opposite surface. Adhesives such as silicone resin (
(not shown), and the hollow portion of the cylindrical metal body 5 is made of heat-resistant, elastic, and stretchable rubber, etc., and has a substantially cylindrical outer shape and a bag-like shape with only one end open. Insert the pressurizer 8. The inside of the pressurizer 8 is filled with a Q gas such as air or a liquid 9 such as oil or water, and pressure is applied to the portion of the pressurizer 8 that is not inserted into the cylindrical metal body 5. The pressurizer 8 is expanded by increasing the internal pressure, and the PTC thermistor 7 is placed in, for example, a dryer while being pressed uniformly from the inside to the outside of the cylindrical metal body 6. Alternatively, the adhesive is thermally cured by heat-treating the positive temperature coefficient thermistor 7 by applying electricity to the positive temperature coefficient thermistor 7 to cause it to self-generate heat. Thereafter, the pressure applied to the pressurizer 8 is removed, the pressurizer 8 is returned to its original state, and then taken out from the cylindrical metal body 5.

Next, at one end of the cylindrical metal body 5, the cylindrical metal body 5 is
A first plate made of metal such as aluminum so as to be in contact with
For example, the rotation support shaft 9 is glued.

Integrate by appropriate means such as brazing or bath welding. Next, a spacer 11 having a through hole concentric with the cylindrical metal body 5 made of an electrically insulating material such as pps is inserted into a through hole provided in the second rotation support shaft 10 made of a metal such as aluminum; Further, a third rotation support shaft 12 made of metal such as aluminum is inserted into the through hole of the spacer 1o, and the common electrode 6 of the PTC thermistor 7 provided on the cylindrical metal body 5 and the third rotation support shaft 12 are inserted into the through hole of the spacer 1o. Support shaft 1
2 to be in contact with each other, for example by adhering or fitting.

It is integrated with the cylindrical metal body 5 by suitable means such as brazing or welding. This completes the manufacturing process.

Note that the pressure applied by the pressurizer 8 is applied to the positive temperature coefficient thermistor 7.
It may be selected appropriately depending on the size of the adhesive, the characteristics of the adhesive, etc.

Moreover, any method and structure for electrically extracting the terminal from the positive temperature coefficient thermistor 7 may be used.

10 between the first rotation support shaft 9 and the third rotation support shaft 11 at both ends of the cylindrical constant temperature heating element configured in this way.
When a voltage of 0 VAC was applied, the positive characteristic thermistor 7
generates heat by itself and heats the cylindrical metal body 5, and the temperature becomes constant due to the self-control function of the positive temperature coefficient thermistor 7.

Effects of the Invention According to the present invention configured as described above, a temperature sensor is provided by the self-control function of a positive temperature coefficient thermistor.

Since there is no need for a temperature control circuit and also no overheating prevention device, the structure is simple, highly safe, inexpensive, and can be downsized.

However, by directly disposing a positive temperature coefficient thermistor on a cylindrical metal body via an adhesive, the cylindrical metal body is directly heated, resulting in very high thermal efficiency, a fast temperature rise rate, and a temperature that can be copied. The waiting time until moreover,
Since the thermal efficiency is improved, toner can be sufficiently fixed with a small amount of electric power, resulting in energy savings.

By arranging the positive temperature coefficient thermistor under uniform pressure, it is possible to reduce the thermal resistance and reduce the variation in the thermal resistance in each part, thereby obtaining a uniform cylindrical constant temperature heating element as a whole. I can do it.

Furthermore, since a large number of positive temperature coefficient thermistors can be disposed at the same time, manufacturing is greatly facilitated.

Furthermore, by providing a tapered cut at the edge of the concave groove on the inner circumference of the cylindrical metal body, the creepage distance and spatial distance between the electrode provided on one surface of the positive temperature coefficient thermistor and the cylindrical metal body 5 are increased. “It is possible to improve electrical reliability.

Further, by providing a tapered cut, the volume of the metal is reduced by the amount of the cut, so the heat capacity becomes smaller, and the temperature increase characteristics are further improved.

As described above, according to the method for manufacturing a cylindrical constant temperature heating element according to the present invention, a cylindrical constant temperature heating element that is easy to manufacture and has excellent performance can be obtained, and its practical effects are extremely large.

[Brief explanation of drawings]

Fig. 1 is a cross-sectional view showing a conventional toner constant wear heater, Fig. 2 is a cross-sectional view showing a cylindrical constant temperature heating element according to the method of the present invention, Fig. 3 (c), and Fig. 3 (B) are sectional views of the present invention. FIG. 3 is a cross-sectional view of a cylindrical constant temperature heating element, seen from the front and side, for explaining the manufacturing method of the invention. 5...Cylindrical metal body 1.6...Common electrode, 7...Positive characteristic thermistor. Name of agent: Patent attorney Toshio Nakao and 1 other person @
1 Figure 2 @ Figure 3

Claims (1)

[Claims] A cylindrical metal body having a circular outer periphery and a plurality of concave grooves each having a tapered edge cut into the inner periphery. A positive temperature coefficient thermistor having an electrode and a common electrode formed on the electrode on the opposite side is respectively arranged via an adhesive,
A cylindrical constant-temperature device characterized in that it is formed by heating and curing an adhesive while pressing each of the positive temperature coefficient thermistors with uniform force from the inside to the outside in a hollow portion of the cylindrical metal body. Method of manufacturing a heating element.