JPH0619367A - Temperature detecting device for fixing device - Google Patents

Abstract

PURPOSE:To obtain the noncontact type temperature detecting device which is inexpensive and makes a good thermal response by coating the surface of a temperature detecting element with a heat collector at least on the side facing a fixing roll. CONSTITUTION:The thermistor element 14 which is arranged opposite the surface of the fixing roll across a specific gap is coated with the heat collector 20 made of aluminum foil. This heat collector 20 is provided in such a folded state that the top and reverse surface of the thermistor element 14 are coated. This heat collector 20 is fitted to the thermistor element 14 as it is so that the thermistor element 14 is held or by being adhered with an adhesive having excellent heat conductivity at need. Further, the heat collector 20 may have the surface colored in black, etc., on the side facing the surface of a heat roll to increase the heat collecting performance and the reverse surface of the heat collector 20 is not colored in this case to maintain its heat radiating performance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature detecting device for detecting the temperature of a heating roll or the like of a fixing device used in an image forming apparatus such as an electrophotographic copying machine or a printer, and particularly to a heating roll or the like. The present invention relates to a non-contact type temperature detecting device capable of detecting temperature without contacting the surface.

[0002]

2. Description of the Related Art Conventionally, as a non-contact type temperature detecting device for detecting the surface temperature of a heating roll of the above fixing device, there is a device using an infrared temperature sensor, or a device using a thermistor or a thermostat.

As the non-contact temperature detecting device, a temperature sensor as disclosed in Japanese Utility Model Laid-Open No. 2-14043 has already been proposed.

The temperature sensor disclosed in Japanese Utility Model Laid-Open No. 2-14043 is constructed such that a print pattern is attached on a heat-resistant resin substrate and a thin film thermistor is mounted on the print pattern.

[0005]

However, the above-mentioned prior art has the following problems. That is, in the case of the temperature detecting device using the infrared temperature sensor, the infrared temperature sensor is expensive, and thus the cost of the fixing device is significantly increased. Further, in the case of a temperature detecting device using a thermistor, a thermostat, etc., it is relatively inexpensive, but the response is poor, and when these are used in the fixing device, the surface of the heating roll generated immediately after the start of the fixing process. Detecting a temperature drop is delayed, causing a drastic temperature drop called droop, or detecting a rise in the surface temperature of the heating roll that occurs after the completion of fixing processing, causing a rapid temperature rise called an overshoot. There was a problem that I was afraid.

The temperature sensor according to the above-mentioned proposal also provides a temperature detecting device which is easy to manufacture and inexpensive, but it also uses a thermistor element and the responsiveness is taken into consideration. Therefore, sufficient responsiveness cannot be expected.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an inexpensive non-contact temperature detecting device having good thermal response. It is in.

[0008]

The above-mentioned technical problems are as follows.
In the temperature detecting device for a fixing device according to the present invention, in a temperature detecting device for a fixing device, at least one of which has a pair of fixing rolls internally having a heating source in pressure contact with each other to fix an unfixed image, This is achieved by arranging a temperature detecting element so as to face the surface of the sheet with a predetermined gap and at least covering the surface of the temperature detecting element facing the fixing roll with a heat collector. . As the heat collector, it is desirable to use a material having a small heat capacity.

[0009]

In the present invention, the temperature detecting element is arranged so as to face the surface of the fixing roll with a predetermined gap,
Since at least the surface of the temperature detecting element on the side facing the fixing roll is configured to be covered with the heat collecting body, the heat collecting body covering the surface of the temperature detecting element prevents radiation heat radiated from the surface of the fixing roll. Heat is collected, and the collected radiant heat can be detected by the temperature detecting element,
The detection accuracy can be improved. In addition, when a material having a small heat capacity is used as the heat collector, the temperature change on the surface of the fixing roll can be immediately detected without accumulating heat, and the non-contact type temperature with good thermal response can be obtained. A detection device can be provided.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to illustrated embodiments.

FIG. 2 shows an embodiment of a fixing device to which the temperature detecting device according to the present invention is applied.

In the figure, reference numeral 1 is a heating roll, and this heating roll 1 is constructed by coating a metal roll 2 with a relatively thin elastic layer 3 made of silicon rubber or the like having heat resistance. . A halogen lamp 4 as a heating source is housed inside the heating roll 1, and the surface of the heating roll 1 is heated from the inside to a predetermined temperature. A pressure roll 5 is pressed against the heating roll 1, and the pressure roll 5 has a relatively thick elastic layer 7 made of silicon rubber or the like having heat resistance on the surface of the metal roll 6. It is configured by coating.

In this fixing device, the heating roll 1 and the pressure roll 5 are kept in pressure contact with both rolls 1,
5 is rotationally driven, and the heating roll 1 is internally heated by the halogen lamp 4. Then, in the nip portion between the heating roll 1 and the pressure roll 5, as shown in FIG.
The toner image is fixed on the transfer paper 8 by heat and pressure by passing the transfer paper 8 carrying the unfixed toner image.

By the way, the temperature detecting device according to this embodiment is arranged with a predetermined gap so as to face the surface of the heating roll.

As shown in FIG. 1, the temperature detecting device 10 has a printed board 11 having a substantially quadrangular plane.
A rectangular opening 1 is formed in the center of the printed circuit board 11.
Two are provided. Further, on the surface of the printed circuit board 11, two printed wirings 13, 13 are formed symmetrically so as to surround the opening 12 from one end side thereof toward the central part. Two terminals 15 and 15 of the thermistor element 14 are fixed to the tips of the printed wirings 13 and 13 by soldering or the like.

As shown in FIG. 3, the thermistor element 14 has lead wires 16 and 16 called dimet wires connected to opposite electrodes of the semiconductor element 15 of the thermistor, and the semiconductor element 15 of the thermistor is made of glass or the like. The lead wires 16 and 16 are coated with a material 17 having good thermal conductivity.
Is covered with insulating tubes 18, 18.

The thermistor element 14 is covered with a heat collector 20 made of aluminum foil, as shown in FIG. The heat collector 20 is provided in a folded state so as to cover the front surface and the back surface of the thermistor element 14. Further, the heat collector 20 is the thermistor element 1
The thermistor element 14 may be sandwiched between the four thermistor elements 14 as they are, or may be attached with an adhesive having good thermal conductivity, if necessary. Further, the heat collector 20 may be colored in a black color or the like with the surface of the heating roll 1 facing the surface to enhance the heat collecting property. In this case, the back surface of the heat collector 20 may be colored. Instead, it is desirable to maintain heat dissipation.

As the heat collector 20, other than an aluminum foil, a copper foil, a copper plate, or a silicon rubber having a high thermal conductivity may be used.

At this time, the heat collector 20 may have a considerably large area in order to improve the heat collecting property.

The temperature detecting device 10 constructed as described above.
As shown in FIG. 5, a predetermined size is set so as to face the surface of the heating roll 1 in a state where the heating roll 1 is mounted on a mounting member 18 having a U-shaped cross section and arranged along the axial direction of the heating roll 1. It is arranged with a gap of.

The printed circuit board 1 is mounted on the mounting member 18.
Groove 18a into which the convex portion 11a protruding from the tip of the No. 1 is fitted
Is provided, and the base end portion 11b of the printed board 11 is fixed to the flange portion 18b of the mounting member 18 by screwing or the like with the convex portion 11a of the printed circuit board 11 fitted in the groove 18a of the mounting member 18. Installed by doing.

With the above arrangement, the temperature detecting device for the fixing device according to this embodiment detects the surface temperature of the heating roll of the fixing device as follows. That is, in the fixing device, both rolls 1 and 5 are rotationally driven while the pressure roll 5 is pressed against the heating roll 1, and the heating roll 1 is heated from the inside by the halogen lamp 4. Then, as shown in FIG. 2, the transfer sheet 8 carrying the unfixed toner image is passed through the nip portion between the heating roll 1 and the pressure roll 5 to heat the toner image on the transfer sheet 8 by heat and pressure. It has become established.

At this time, the surface temperature of the heating roll 1 is
It is detected by the temperature detection device 10. The temperature detecting device 10 includes a thermistor element 14 which is arranged with a predetermined gap so as to face the surface of the heating roll 1, and the thermistor element 14 is covered with a heat collecting body 20. . Therefore, the radiant heat radiated from the heating roll 1 is collected by the heat collector 20, and the radiant heat is collected by the heat collector 2.
Radiation collected by 0 is detected by the thermistor element 14.

As described above, the thermistor element 14 is arranged so as to face the surface of the heating roll 1 with a predetermined gap, and both the front and back surfaces of the thermistor element 14 are covered with the heat collector 20 having a small heat capacity. Since it is configured, by the heat collector 20 that covers the surface of the thermistor element 14,
Radiant heat radiated from the surface of the heating roll 1 can be collected, and the collected radiant heat can be detected by the thermistor element 14, so that detection accuracy can be improved and the heat collector 20 has a small heat capacity. Therefore, it is possible to immediately detect a temperature change on the surface of the heating roll 1 without accumulating heat, and it is possible to provide a non-contact type temperature detection device having good thermal response.

FIG. 6 shows another embodiment of the present invention. The same parts as those in the above-mentioned embodiment are designated by the same reference numerals. In this embodiment, the thermistor element 14 is covered with aluminum. The heat collector 20 made of foil is provided only on the side facing the surface of the heating roll 1.
No. 0 is attached in a state of being adhered by an adhesive 25 having good thermal conductivity.

The planar shape of the heat collecting body 20 does not necessarily have to be a rectangular shape, and is appropriately set in consideration of heat collecting characteristics and thermal response.

The other structure and operation are the same as those of the above-mentioned embodiment, and the explanation thereof will be omitted.

[0028]

According to the present invention, which has the above-described structure and operation, it is possible to provide a non-contact temperature detecting device which is inexpensive and has a good thermal response.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a temperature detecting device according to the present invention.

FIG. 2 is a block diagram showing a fixing device to which an embodiment of a temperature detecting device according to the present invention is applied.

FIG. 3 is a configuration diagram showing a thermistor element.

4A and 4B are a side view and a plan view, respectively, showing a state in which a thermistor element is covered with a heat collector.

FIG. 5 is a configuration diagram showing a mounting state of the temperature detecting device.

FIG. 6 is a side view showing another embodiment of the present invention.

[Explanation of symbols]

1 heating roll, 4 halogen lamps, 14 thermistor elements, 20 heat collectors.

Claims (1)

[Claims] 1. A temperature detecting device for a fixing device for fixing an unfixed image by pressing a pair of fixing rolls, at least one of which has a heating source therein, to form a predetermined gap on the surface of the fixing roll. And a temperature detecting element is disposed so as to face each other, and at least the surface of the temperature detecting element facing the fixing roll is covered with a heat collecting body.