JPS59151176A - Heat fixing device - Google Patents

Abstract

PURPOSE:To reduce considerably a preheating time and to prevent the decrease in the surface temp. of a heating roll having a resistance heating element layer in the stage of passing paper by providing a radiation heat source in the roll. CONSTITUTION:A heating roll 1 is formed of a hollow core 5 made of a metal, and a resistance heating layer 8 is formed via a coupling layer 6 and an insulating layer 7 on the outside circumference thereof. A radiation heat source 11 of a nichrome wire is provided in the core 5. The layer 8 is formed of TiO2 ceramics and a voltage is impressed thereon through annular electrodes 9, 9a, by which a surface temp. of 200 deg.C is obtd. in several to several tens seconds. The voltage is impressed on the source 11 as well in the stage of use, so that the roll 1 is heated from the inside, too. The preheating time is thus considerably reduced and the decrease in the surface temp. in the stage of passing paper is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heating chamber @ apparatus, and in particular, toner images formed on a support such as paper in an image forming apparatus such as an electrophotographic copying machine, a NOAXIMILY, and a PRINTER printer. This invention relates to a heat fixing device that fixes images using a heating roll and a pressure roll.

As one of the fixing devices in the image forming apparatus, a heat-resistant elastic material such as silicone rubber is used as a metal core with good thermal conductivity, which has a heat source such as an infrared lamp, a halogen lamp, and a nichrome wire inside. A so-called heat roll type heat fixing device is known, which includes a heat roll and a pressure roll coated with a releasable layer such as body layer or DEFLON (trade name).

In this type of heat fixing device, the heating efficiency is poor because the roll body is indirectly heated through the air by the radiant heat of the heat source inside the heat roll, and the surface of the heat roll is The drawback is that it takes a long time to preheat (about 3 to 5 minutes) to reach the fixing temperature (usually around 150 to 180 degrees Celsius). Therefore, in order to shorten this preheating time, for example, Japanese Patent Laid-Open No. 56-123581 and Japanese Patent Laid-open No. 5
It has been proposed to directly heat the roll body with a resistance heating element such as a ceramic heater as described in Japanese Patent No. 6-'138766.

According to this direct heating type fixing device, the preheating time can be shortened compared to the conventional radiation heating type.
A preheating time of about 2 minutes was required.

Furthermore, as a resistance heating element, a ceramic heating element having a positive temperature coefficient of resistance, or so-called PTC characteristic, is known. Is this PTC characteristic 1'? The Hiramic heating element has a self-temperature control function because it can achieve a predetermined heat generation temperature by selecting the Curie salinity, has a fast temperature rise time, and has a self-temperature control function because the resistance increases rapidly at a constant temperature. There are advantages such as:

However, the generally known [3a TiO3-based ceramic heating element has not been put into practical use because it takes time and effort to manufacture, and it requires extreme rotation to obtain one with high dimensional accuracy. do not have.

Further, improvements to this type of ceramic heating element are also disclosed, for example, in JP-A-55-164.859 and JP-A-56-13876.
Although such methods have been proposed in various publications such as No. 6 and Japanese Patent Laid-Open No. 56-123581, they cannot be said to be sufficient.

The present invention solves the problems of the prior art as described above, and provides a heat fixing device that can significantly shorten the preheating time and prevent the surface temperature of the heating roll from decreasing during paper passing. Its purpose is to provide.

The present invention is characterized in that a fixing device is configured such that a support carrying a 1-toner image is passed between a heating roll having a resistive heating layer and a pressure roll that is in pressure contact with the heating roll. The heat fixing device is provided with a radiant heat source in the part I) of the roll.

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

Here, FIG. 1 is a partially vertical front view of a heat fixing device according to an embodiment, and FIG. 2 is a sectional view taken along the line AA in FIG. 1.

In the figure, 1 is a heating roll, 2 is a pressure roll,
3, 3a and 3b, 30 are bearings, 4.4a respectively
are side plates; the heating roll 1 is rotatably supported by the side plates 4, 4a via bearings 3.degree. 3a, and the pressure roll 2 is rotatably supported by the side plates 4, 4a via bearings 3b, 3C.

5 is the metal hollow that constitutes the heating roll 1 = 17.6
7 is a bonding layer, 7 is a constant R layer, and 8 is a resistance heating layer, which are formed on the outer periphery of the hollow core 5 with a bonding layer 6 and an insulating layer 7 interposed therebetween. Reference numerals 9 and 98 denote ring-shaped electrodes made of a conductive material such as C1,1 alloy, which are attached near both ends of the outer peripheral surface of the resistance heating layer 8 with a gap larger than a predetermined fixing width. Ru. This ring-shaped type 113M9.9a is in contact with a power supply brush (not shown), such as a Nocobon, which is connected to a power source through a wire connection. Reference numeral 10 denotes a releasable layer formed on the outer circumferential surface of the resistance heating element B8 with a length corresponding to the fixing width.

Reference numeral 11 denotes a radiant heat source made of a nichrome wire installed inside the hollow core 5. This radiant heat source 11 may be a halogen lamp, an infrared lamp, or the like.

12 is a metallic hollow core constituting the pressure roll 2;
3 is a heat-resistant elastic body/layer formed to cover the outer peripheral surface of the hollow core 12.

Next, details of each component of the heating roll 1 described above are as follows.

The resistance heating layer 8 can be put to practical use by forming it from TiO2 ceramic. TlO2-based ceramics are expressed by the chemical formula 1゛102-X (0≦×1), and as X becomes larger, the specific resistance becomes smaller. In this case, by controlling the production atmosphere, TlO2-
It is possible to adjust X of x, and for example, culm X, where the reducing nature of the atmosphere becomes stronger, becomes a dog. The characteristics of this TiO2-based ceramic are that it has great corrosion resistance, low power consumption (40V x 5A to 50V In addition to the advantages of 1JJ, it is also possible to easily form a resistive film by plasma spraying using raw material powder. In other words, with the 1-i02 series ceramic, plasma spraying can be applied as a means of forming a resistive film, so the manufacturing cost is significantly reduced compared to the Ba'Fi○3 series ceramic, and it is possible to use conventional radiant heat. It becomes possible to manufacture heating rolls at the same or lower cost than when using a heat source. However, TiO2-based ceramics have a negative temperature coefficient of resistance, meaning that the resistance decreases as the temperature increases. It is necessary to include a control circuit that de-energizes the layer.

The insulating layer 7 is for electrically insulating the hollow 2175 of the resistive heating element layer 8, and various types of abrasive materials can be used. Δ120a ・MgO is suitable.

The bonding layer 6 is a bonding layer for securely fixing the insulating layer 7 to the hollow core 5, and is made of hollow material such as J, 7, etc.
)”-CLJ may be omitted.

- The thickness of the resistance heating element layer, insulating layer and bonding layer as described in
It may be set as appropriate depending on the fixing temperature, material composition) and the ma1 method (length, outer diameter, inner diameter) of the hollow core. for example,
Hollow] A is 270mm (length) x 34.5mmφ, outer diameter is 32mmφ (inner diameter), and ankle temperature is 190-210℃
In the case of , the resistance heating layer (r!02) is 50-70/
About i m, the insulating layer (AlpOH (・M!110) is
about 150 to 200 g1n, and a bonding layer (Ni-Ai
-Mo), 50 um per culm is appropriate.

The radiant heat source 11 may be a normal radiant ray, heat lamp, infrared lamp, or the like.

Next, the fixing operation of the above-mentioned (4-component heat fixing device) will be explained.

First, the heat applied to the 1-ru 1 and the 11-pressure force [1-ru 1 and 11 pressure [l-ru 2] are rotated by a drive mechanism (not shown), and then a heavy load is applied to the power supply brush from a commercial AC power source. 11, a current flows through the ring-shaped electrodes 9 and 9a to the resistance heating layer 8, and the heating roll 1 is heated.

Further, by applying a voltage to the radiant heat source 11, radiant heat is generated, and the heating roll 1 is heated fp 111 from inside.

Now, between heating []-ru 1 and pressure [-1-ru 2] 1~
When the plane passes through the support holding the planer, the temperature of the resistor R heating layer 8 increases, but due to the heat from the radiant heat source 11.J, the surface of the heating roll 1 increases. A decrease in temperature is prevented and a high quality fixed image can be obtained.

In addition, in the heating system 1, a heat-resistant elastic layer such as silicone rubber may be formed on the top of the resistance heating layer 8, and a releasable layer such as deflon may be formed thereon.

On the other hand, in addition to the above, the pressure roll 2 also has a
A heat-resistant elastic layer is formed on a 7-core core and the IQ is 5.

As explained above, the 1"11 thermal shield according to this embodiment has a bonding layer 6 on the outer periphery of the metal hollow core 5.
A -C resistance heating element layer 8 is formed via the insulating layer 7 and radiant heat H! 11 and heated [Ale 1 is depicted.

Therefore, if power is supplied from the power source to the f-ring electrodes 9, 9a via the power supply brush, and at the same time, power is supplied to the radiant heat source 11, the temperature of the resistance heating layer 8 during paper feeding can be prevented from decreasing. Radius q4 Heat source 1'1 generates heat U=J, which prevents the surface temperature of heating roll 1 from decreasing and produces a high-quality fixed image 1q.

As described above, the present invention has the advantage of significantly reducing the preheating time and improving IJll thermal stability by preventing the surface temperature of the heating roll from decreasing during paper passing. It can be said that the invention has excellent practical effects because the device can be used for a long time.

[Brief explanation of drawings]

FIG. 1 is a partial vertical R7i + sectional view of a heating fixing device according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line Δ-A in FIG. DESCRIPTION OF SYMBOLS 1: Heating eye, 2: Pressure roll, 8: Resistance heating element layer, 1'1: Radiant heat source. -46:

Claims (1)

[Claims] In a fixing device configured to pass a support holding a toner image between a heating roll that heats the resistance heating layer and a pressure roll that is in pressure contact with the heating roll, the inside of the heating roll is A heat fixing device characterized in that a radiant heat source is provided.