JPH0293574A - Fixation device - Google Patents

Abstract

PURPOSE:To easily adjust a gap at the time of assembling by attaching a supporting member which supports a temperature detector by setting the bearing of a fixing roller as reference. CONSTITUTION:The temperature detector 4 is made to adhere to a holder 5, which is a rigid body and is formed by being concentrically bent with the fixing roller 1 and whose diameter is made to coincide with the diameter of the bearing 7. As to the length of the holder 5, the holder 5 is so long that it is made to butt against the right and left bearings 7 of the fixing roller 1 and fastened to the side plate 6 of a machine with a screw, etc., and the surface of the holder 5 on the fixing roller 1 side is finished to be a mirror surface. Since the bearing 7 is in a narrow tolerance range, the gap between the fixing roller 1 and the temperature detector 4 is adjusted by making both ends of the holder 5 butt against the bearing 7 by utilizing the above-mentioned effect. Thus, the gap between the fixing roller 1 and the temperature detector 4 can be easily adjusted with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device in which a non-contact temperature sensor is disposed near a fixing roller.

Fixing devices of the above type are well known, and include electrophotographic copying machines, -
Used in electrostatic recording equipment such as printers and facsimiles. In this type of fixing device, the surface temperature of the fixing roller is detected, and the heating temperature of a heater or the like is controlled based on the detected surface temperature. Various methods have been proposed for temperature detection at this time, and one known method is to use a non-contact temperature sensor. Although this non-contact temperature detection method has various advantages, it is important to adjust the gap between the fixing roller and the detector during assembly.

A conventional temperature sensor uses a glass-enclosed type thermistor, and the tip of the thermistor is connected through many parts. For this reason, when adjusting the gap, the stacking tolerance is large when the material supporting the temperature sensor is used as a reference.Therefore, this type of gap adjustment cannot be adopted due to the large error. During adjustment, the tip of the detector was brought into contact with the fixing roller and separated from it by a predetermined distance.

However, with this method of obtaining the gap, the tip of the thermistor in the detector is delicate and fragile, which can cause deformation or damage if not handled with sufficient care, making the process extremely difficult.

The present invention aims to solve the above-mentioned conventional problems, and to provide a fixing device in which the gap can be easily adjusted during assembly, and a temperature sensor with good responsiveness can be assembled. There is.

for The structure of the present invention that achieves the above object is as follows.

(1) In a fixing device in which a non-contact temperature sensor is disposed near the fixing roller, a support member is provided to support the temperature sensor, and the support member is attached with reference to the bearing of the fixing roller. A fixing device characterized by:

(2) A thin film thermistor is used in the detection part of the temperature sensor, the supporting member covers the opposite side of the temperature sensor to the side facing the fixing roller, and a hole is formed in a portion corresponding to the thermistor. The fixing device according to (1) above, characterized in that:

(3) The above (1) or (2) characterized in that a cover member that covers the hole is provided on the outside of the support member.
The fixing device described in .

Operation-1- According to the above configuration, by utilizing the fact that the bearing conforms to a very narrow tolerance range, the support member that supports the temperature sensor is abutted against the bearing and fixed. If a thin film thermistor is used in the detection part of the temperature sensor, it can be glued to the support member, but if it is glued to the entire surface of the support member, it will cause problems during startup.

Since the amount of heat is large and the response is poor, a hole is provided in the part where the thermistor is located. The hole is then covered with a thin windshield film to prevent wind from affecting the thermistor.

311 animals Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 is a fixing roller, 2 is a pressure roller, 3 is a heater built into the fixing roller 1, 4 is a temperature sensor that detects the temperature of the fixing roller 1, and 5 is a temperature sensor 4. This is a holder that serves as a support member that supports the. As shown in FIG. 2, the fixing roller 1 is rotatably supported by a machine side plate 6 via a bearing 7, and is rotationally driven by a drive device (not shown) by a gear 8.

The temperature sensor 4 has a three-layer structure including a base 9, a thin film thermistor 10, and a protective film 11, as shown in FIG. is connected.

Since the temperature sensor 4 thus configured is a thin film, it is supported by being adhered to the holder 5. The holder 5 is a rigid body made of sheet metal in this embodiment, and is curved concentrically with the fixing roller 1, as shown in FIGS. It matches the diameter of Further, the length of the holder 5 is long enough to abut against the left and right bearings 7 of the fixing roller 1 and tighten it to the machine side plate 6 with screws, etc. has a mirror finish. This mirror finish improves thermal efficiency and increases the sensitivity of the temperature detector 4.

Since the thermistor 10 of the temperature sensor 4 is in the form of a thin film, it has a small heat capacity and responds in 1/10 of the time compared to a conventional glass-enclosed type thermistor, greatly improving detection accuracy. Furthermore, the temperature sensor 4 can be supported by adhesive along the inner surface of the curved holder 5. It should be noted that good thermal response was obtained when the thickness of the protective film 11 was 50 μm, but if a thinner layer was used, the thermal response would be better, but manufacturing would be difficult, so there is a trade-off. The most effective color may be selected.Although black is the color of the protective film 6, which is excellent in terms of heat absorption and has good efficiency, transparent is also preferable because infrared rays can easily pass through it, directly warming the thermistor.

In the temperature sensor 4 thus constructed, both ends of the holder 5 are brought into contact with the bearing 7 during assembly, and both ends are fastened to the machine side plate 6 with screws, as shown in FIG.

In this manner, the fixing device according to the present invention adjusts the gap between the fixing roller 1 and the temperature sensor 4 by abutting both ends of the holder 5 against the bearing 7 by utilizing the fact that the bearing 7 adheres to a very narrow tolerance range. ing.

Therefore, the gap between the fixing roller 1 and the temperature sensor 4 can be easily adjusted with high accuracy.

By the way, when the temperature sensor 4 is glued to the holder 5,
Since the heat capacity is large, the responsiveness of the temperature sensor 4 may deteriorate.

Therefore, in this embodiment, as shown in FIG.
A hole 13 is provided in a portion facing the thermistor 10 to reduce the heat capacity of the thermistor 10 portion.

However, if only the hole 13 is provided, wind will hit the thermistor 10 and the temperature sensor 4 will become unstable. Therefore, a thin film for a windshield constituted as a cover member 14 is attached to the hole 13 from the outside of the holder 5. ing. This cover member 14 prevents the thermistor 10 from being affected by wind even if the hole 13 is provided.

Effects According to the first aspect of the present invention, since the temperature detector is assembled based on the bearing of the fixing roller, the gap between the fixing roller and the temperature detector can be accurately adjusted.

Further, according to the second aspect, since the hole is provided in the portion of the support member corresponding to the thermistor, the heat capacity of the thermistor portion is reduced and its sensitivity is improved.

Furthermore, according to claim 3, the outside of the hole is covered with a cover member to prevent the influence of wind on the thermistor, thereby stabilizing its response.

[Brief explanation of drawings]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is a sectional view of the fixing roller, FIG. 3 is a sectional view showing the structure of the temperature sensor, and FIG. 4 is a perspective view of the holder. FIG. 5 is a cross-sectional view of the temperature sensor adhered to the holder. 1... Fixing roller 4... Temperature detector 5... Holder 10... Thermistor 13... Hole 14... Cover member

Claims (3)

[Claims] (1) In a fixing device in which a non-contact temperature sensor is arranged near the fixing roller, a support member is provided to support the temperature sensor, and the support member is attached with reference to the bearing of the fixing roller. A fixing device characterized by: (2) A thin film thermistor is used in the detection part of the temperature sensor, the supporting member covers the opposite side of the temperature sensor to the side facing the fixing roller, and a hole is formed in a portion corresponding to the thermistor. The fixing device according to claim 1, further comprising a fixing device. (3) The fixing device according to claim 1 or 2, wherein a cover member that covers the hole is provided on the outside of the support member.