JPS5853556Y2 - Thermocouple device for temperature control of fuser unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermocouple device for controlling the temperature of a contact heating type roller fixing device used in an electrophotographic apparatus.

For example, a heat fixing device that passes a transfer paper between a pair of pressure rollers (two) and melts the toner made of thermoplastic resin by the heat of the rollers and fixes it on the transfer paper has a high fixing ability, so it is suitable for high-speed copying machines. However, since the temperature of the roller, which is a heating element, determines the quality of fixing, temperature control is an important requirement.

FIG. 1 shows an example of an electrical temperature detection device for the surface of a roller conventionally used for such temperature control, in which a thermocouple 1 is embedded in a carbon brush 3 supported by a support member 4. , thermocouple 1 via this carbon brush 3
By adopting a structure in which the heating roller 2 is brought into sliding contact with the surface of the heating roller 2, control with excellent thermal responsiveness is attempted.

However, in such a device, not only is there a problem with the durability of the carbon brush 3, but also the surface is coated with Teflon, or the heating roller is coated with silicone resin or silicone rubber to improve mold releasability for resin toner. However, there is also the problem that the carbon brush 3 damages their surfaces and cannot be used.

The present invention is intended to provide a simple thermocouple device that has excellent thermal response and does not damage the heating roller, in order to solve the problems of the conventional devices described above.

Hereinafter, details of the present invention will be explained based on the drawings.

Figures 2 and 3 show an embodiment of the present invention, in which 6 is a sliding joint made of a thin stainless steel plate, and the back side is covered with a thin sheet of tetrafluoroethylene resin such as Teflon. A coating 7 is formed, and an electrode constituting a thermocouple 1 is spot welded to the tip surface with its flat surface brought into close contact with the sliding contact 6.

Reference numeral 8 denotes a support member that holds the sliding contact 6 in the direction of rotation of the heating roller 2; The sliding contact 6 is swingably supported on a shaft 9 provided on this member.

In addition, the reference numeral 6a in the figure is a cut and raised piece provided on the sliding contact 6, which holds the lead wire of the thermocouple 1 on the sliding contact, and 10 is a cut-and-raised piece provided on the sliding contact 6 to press the sliding contact 6 onto the surface of the heating roller 2. weak spring, 11
Reference numeral 8a indicates a mounting rod attached to the machine frame, reference numeral 8a indicates a mounting hole drilled in the rear end of the support member 8, and reference numeral 12 indicates a mounting screw.

In the embodiment described above, the spring 10 causes the heating roller 2 to
The sliding contact piece 6 pressed against the surface of the heating roller 2 absorbs the pressing force by the elastic deformation of its own thin stainless steel plate, and in combination with the small friction coefficient of the Teflon coating provided on the back side, it softly contacts the surface of the heating roller 2. The heat is then efficiently transferred to the thermocouple 1.

The one shown in FIG. 4 is another embodiment of the present invention, in which a sliding contact 16 made of a very thin stainless steel plate with a Teflon coating on the back side is configured to be directly attached to the mounting rod, and the tip of the surface A thermocouple 1 is attached by spot welding as in the above-described embodiment.

In addition, the code|symbol 16a is a cut-and-raised piece which holds a lead wire, 1
6b indicates a mounting hole.

As described above, according to the present invention, the temperature control thermocouple of the fuser is in contact with the heating roller through the elastic thin plate that constitutes the sliding contact, so this temperature can be accurately detected and controlled. to ensure that.

Furthermore, the sliding contact facing in the direction of rotation of the heating roller makes moderate contact with the heating roller due to its own elasticity, and also slides into contact with the surface of the heating roller due to the small friction coefficient of the fluororesin formed on its back surface. Therefore, it has excellent effects as a thermocouple device for temperature control of a fixing device, such as not damaging the surface of a heating roller coated with fluorine or a heating roller made of silicone rubber.

[Brief explanation of drawings]

Fig. 1 is a vertical side view of a conventional device, Fig. 2 is a longitudinal side view of a device showing an embodiment of the present invention, Fig. 3 is a perspective view of the same device, and Fig. 4 is another embodiment of the present invention. FIG. 1...Thermocouple, 2...Heating roller, 6
, 16...Sliding joint, 7...Fluororesin coating, 8...Supporting member, 11...Mounting rod.

Claims (1)

[Scope of utility model registration request] A thermocouple is fixed to the tip of the surface of a sliding contact made of a thin elastic plate with a fluororesin coating on the back side, and the tip of the sliding contact is brought into contact with the surface of a heating roller with the tip facing in the direction of rotation. A thermocouple device for temperature control of a fixing device, characterized by: