JPS62200379A - Heat roller fixing device - Google Patents

Abstract

PURPOSE:To reduce the power consumption by providing a heat roller provided with a heat insulating layer consisting of a heat insulating material which is formed on the outer peripheral surface of a supporting roller, and a heater film having a small heat capacity formed on the outer peripherals surface of the heat insulating layer. CONSTITUTION:The titled device consists of a heat insulating structure reducing the heat capacity of a heater film 4 and a covered layer 5 in order to shorten the leading time of a heat roller 1. That is to say, their heat capacity is reduced by setting the thickness of the heater film 4 and the thickness of the covered layer 5 to <=20mum and <=10mum, respectively. When power is supplied to the heater film 4 of the heat roller 1, the heater film 4 generates Joule heat. The heat insulating structure is formed by forming the thickness of a heat insulating layer 3 of the heat roller 1 is formed to >=about 1mm, and the leading time for reaching a fixing temperature from a room temperature can be set to <=3sec by setting the power to two times of the power required for the fixation. The temperature rise of the surface layer of the heat roller 1 by the heater film 4 is detected by a temperature sensor 7, and its output is inputted to a temperature control part 8. In accordance with this input signal, the temperature control part 8 controls a power supply to the heater film 4 so that the surface layer part temperature of the heat roller 1 becomes the fixing temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a heat roll fixing device used in electrophotographic devices, etc., and particularly to a heat roll fixing device that has a short startup time and does not require high temperature maintenance during stoppage. .

[Conventional technology]

The heat roll fixing device is a device that melts and fixes unfixed toner on the recording paper, and is mainly composed of two rolls, including a heat rolled backup roll.

Conventionally, such a heat roll has an infrared lamp inside, and this infrared lamp is electrically controlled to maintain the heat roll surface temperature at around 180° C. during a fixing operation.

This heat roll is usually made of a metal with high thermal conductivity, such as aluminum, and is made of a cylinder with a wall thickness of about 3 m+, and its surface layer is made of polytetrafluoroethylene (
The toner is coated with a toner release material such as Teflon. On the other hand, a rubber roll such as silicone rubber is used as the backup roll.

[Problem that the invention seeks to solve]

However, in such a conventional example, since the heat roll and the infrared lamp have a large heat capacity, the rise time is usually about 1 to 5 minutes, and the heat roll and the infrared lamp have a large heat capacity. It is necessary to maintain the temperature of the roll at or near the fixing temperature.

Therefore, there is a problem in that the waiting time after the power is turned on is long and inconvenient, and power loss occurs in order to maintain the heat roll temperature when the toe winding is stopped.

Moreover, when maintaining the heat roll at a high temperature, it is necessary to continue exhausting air outside the apparatus using a fan, etc., in order to prevent the temperature of the photosensitive drum from rising. Since it is necessary to have a distance of 10α or more, there is a problem in that the electrophotographic apparatus and the like become larger.

Another conventional example is a "fixing temperature control device" described in Japanese Patent Laid-Open No. 58-192065. This conventional example has a structure in which a planar heating element is coated on the surface of an insulating fixing roll made of ceramic or the like.

Although the heat capacity of the planar heating element and heat roll shown here is not specified, the heat roll uses an electric insulator with relatively high thermal conductivity such as ceramic, so it is heated during fixing. The entire roll is heated and maintained to the same level as the fixing temperature.

Another conventional example is a "fixing roll" described in Japanese Utility Model Publication No. 58-48680. This conventional example shows a fixing roll, that is, a heat roll, which has a structure in which a heat-resistant insulating film and a heating resistor are provided on the inner surface of a conductor core. This fixing roll needs to be heated and maintained as a whole to the fixing temperature in order to bring its surface to the fixing temperature.

Therefore, in the two conventional examples mentioned above, it is necessary to heat and maintain the entire fuser roll, so the rise time of the fuser roll cannot be shortened, and the rise time that practically does not require temperature control during stoppage, that is, several seconds. There is a problem in that the rise time cannot be reduced within a certain range.

The present invention has been made to solve the above problems, and its purpose is to provide a heat roll fixing device that has a short rise time and does not require high temperature maintenance during stoppage.

[Means for solving problems]

In order to achieve the above object, the present invention provides a heat roll fixing device in which a heated heat roll performs fixing while rotating, and a heat insulating layer made of a heat insulating material formed on the outer peripheral surface of a heat roll and a support roll. and a heater film having a small heat capacity formed on the outer peripheral surface of the thermal insulation layer.

[Effect]

In the present invention having the above characteristics, first, when AC power or DC power is supplied to the heater film of the heat roll, the heater film generates Joule heat. At this time, the surface temperature of the heat roll rises to the fixing temperature in a short time because the heat roll has an adiabatic structure in which a heater film is formed on the outer peripheral surface of a heat insulating layer.

Next, the recording paper is fixed while the heat roll rotates. That is, the unfixed toner on the recording paper is thermally melted and fixed by the heater film.

However, when the fixing operation stops, the power supply to the heater film is cut off, and the surface temperature of the heat roll drops to room temperature level. However, even if the temperature drops to room temperature, the rise time is short as described above, so there is no problem in starting the next operation.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on FIGS. 1, 2, and 3.

FIG. 1 is a longitudinal sectional view showing an embodiment of a heat roll fixing device according to the present invention.

In FIG. 1, the heat roll 1 includes a thermal insulating layer 3 formed on the outer circumferential surface of a support roll 2, a heater film 4 formed on the outer circumferential surface of the thermal insulating layer 3, and a and a coating layer 5 for releasing the toner.

The thermal insulation layer 3 is made of asbestos, polyimide resin, or silicone resin, which has electrical insulation and heat resistance, and has a thermal conductivity of 10-2 J/cm s*K or less, and has a thickness of 1. ■Form as above to create a heat insulating structure.

The heater film 4 is made of NiCr or Ni-W-P.
It is formed by vapor deposition, sputtering, thick film printing, dipping, or plating. The coating layer 5
is made of polytetrafluoroethylene (Teflon), etc., which has good toner pattern properties and prevents toner from sticking.

Further, in the present invention, in order to shorten the rise time of the heat roll 1, the heat capacity of the heater film 4 and the coating layer 5 is reduced to provide a heat insulating structure. That is, in this embodiment, the thickness of the heater film 4 is set to 20 μm or less, and the thickness of the coating layer 5 is set to 10 μm or less, thereby reducing their heat capacity. Joule heat is generated using electric power or DC power, and its resistance value is determined with respect to the supply voltage so that Joule heat can be generated from 1.5 times to twice the amount of heat required for fixing.

A backup roll 6 made of silicone rubber or the like is placed opposite the heat roll 1 to form a contact width necessary for fixing. A temperature sensor γ such as a thermistor detects the surface temperature of the heat roll 1.

The temperature control section 8 controls the power supply to the heater membrane 4 according to the output of the temperature sensor 7. 9 is a recording paper carrying unfixed toner.

FIG. 2 is a diagram showing temporal temperature changes in the surface layer of the heat roll depending on the heat generation state of the heater film, and FIG. 3 is a partial side sectional view showing an embodiment of the heat roll fixing device according to the present invention. In FIG. 3, ring-shaped electrodes 10 are provided at both ends of the heat roll 1 and are in electrical contact with the heater film 4. As shown in FIG.

The sliding electrode 11 is in electrical contact with the rotating electrode 10 while sliding.

Next, the operation of the above configuration will be explained. First, when AC power or DC power is supplied to the heater film 4 of the heat roll 1, the heater film 4 generates Joule heat.

At this time, the thickness of the heat insulating layer 3 of the heat roll 1 is set to IIW.
Since the heat roll fixing device is formed to have a thickness of about 1 or more and has a heat insulating structure, the start-up time is about 1 second as shown in Figure 2, assuming a power of 400 W, even for a heat roll fixing device that is equivalent to the width of A4 paper.
It is. Therefore, the start-up time from room temperature to the fixing temperature can be set to 3 seconds or less by using twice the power required for fixing.

The temperature rise in the surface layer of the heat roll 1 caused by the heater film 4 is detected by a temperature sensor 7, and its output is input to a temperature control section 8. In response to this input signal, the temperature control unit 8 controls the power supply to the heater film 4 so that the temperature of the shallow layer of the heat roll 1 becomes the fixing temperature.

On the other hand, the heat roll 1 is driven by a drive motor (not shown).
It rotates in the direction of arrow A in the figure, and at the same time, the backup roll 6 rotates in the direction of arrow B in FIG. Here, during the fixing operation, the recording paper 9 loaded with unfixed l/toner is inserted between the heat roll 1 and the backup meal 6.

At this time, the unfixed toner on the recording paper 9 described above is thermally melted by the heater film 4 and fixed. Also, during fixing, the temperature difference between the support roll 2 and the surface layer of the heat roll 1 is 5
The temperature is above 0℃.

Similarly, if the support roll is made of a material with high thermal conductivity such as metal as a configuration other than this example, and the thermal insulating layer is formed to be thinner than 1 mm, it is possible to have a heat insulating structure with respect to the heater film. However, the rise time is long and the heat loss due to thermal conduction is also large. Therefore, the support roll may be formed of a material with low thermal conductivity and may be integrated with the thermal insulation layer.

Further, even if the support roll 2 is made of a metal with high thermal conductivity, the temperature difference between the surface layer of the heat roll 1 and the support roll 2 is practically 10% due to the effect of the heat insulation structure described above.
The temperature is 0°C or higher, and there is little heat loss due to thermal conduction. Therefore, the support roll 2 can be directly driven.

〔Effect of the invention〕

As described above, according to the heat roll fixing device according to the present invention, the startup time can be shortened due to the heat insulating structure in which the heater film is formed on the outer peripheral surface of the heat insulating layer, so the waiting time after power is turned on can be shortened. Furthermore, even if the surface temperature of the heat roll is lowered to the room temperature level while the fixing operation is stopped after the power is turned on, there is no problem in starting the next operation. Therefore,
There is an effect that no power is consumed when wading while stopped.

Further, according to the present invention, the power consumed during fixing is reduced to 1.5
Since the heat roll can be raised from room temperature to the fixing temperature with twice to twice as much power, the conventional example consumes three to four times as much power during fixing as the start-up power in order to shorten the start-up time. However, power consumption can be reduced. Therefore, there is an effect that the capacity of the power supply can be reduced.

Moreover, since the thermal isolation structure around the heat roll fixing device can be relaxed, the distance between the heat roll fixing device and the heat roll photosensitive drum can be reduced, and the overall size of the apparatus can be reduced. Furthermore, the present invention has the advantage that it can be applied to uses other than heat roll fixing devices of electrophotographic devices, for example, devices using a thermal transfer method.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, FIG. 2 is a diagram showing temporal temperature changes of the heat roll depending on the heating state of the heater film, and FIG. 3 is an embodiment of the present invention. FIG. 1...Heat roll 2...Support roll 3...
Thermal insulation layer 4... Heater film 5... Covering layer 6...
・Bank up roller 7...Temperature sensor 8...
Temperature control unit 9...for recording, i 10...electrode 1
1... Sliding electrode patent applicant Takashi Kanakura, patent attorney representing Oki Electric Industry Co., Ltd. 2 Longitudinal cross-sectional view showing an embodiment of the present invention @l1m%2[i

Claims (1)

[Claims] In a heat roll fixing device in which a heated heat roll performs fixing while rotating, the heat roll includes a heat insulating layer made of a heat insulating material formed on the outer peripheral surface of a support roll, and a heat insulating layer. A heat roll fixing device characterized by comprising a heater film having a small heat capacity formed on an outer peripheral surface.