JPS6193474A - Heat fixing device - Google Patents

Abstract

PURPOSE:To minimize the temp. fluctuation on the surface of a heat fixing roller by accumulating once the heat supplied from a heat source in a latent heat accumulating material packed in a rotating body for heat fixing then transferring the same to the surface of the heat fixing roller. CONSTITUTION:A stationary base material cylinder 14 consisting of a metal such as aluminum and a base material cylinder 12 under rotation are concentrically disposed on the inside and outside apart at a prescribed spacing from each other and the latent heat accumulating material 13 is packed into such spacing 15. Pentaerythritol which is the main heat accumulating body absorbs heat via the cylinder 14 heated by a halogen heater 2 provided therein and is accumulated at 188 deg.C. The pentaerythritol in which the heat is accumulated is effectively agitated by fins 16 when the outside cylinder 12 of the heat fixing roller 1 rotates. The cylinder 12 is thus maintained at the extremely stable temp. of 175-178 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Industrial Application Field] The present invention relates to a heat fixing device in a device such as an electrophotographic device or an electrostatic recording device. More specifically, the present invention is applied to a fixing device using a heat fixing rotating body for heat treatment or heat pressure treatment to fix an unfixed image of toner made of resin or the like onto a recording material.

[Conventional technology]

The heat fixing device described in 1U and i, te, f,! Conventionally, a method in which oil paper is sandwiched and conveyed between a heat fixing roller and a pressure roller has been widely used because of its excellent thermal efficiency.

[Problem that the invention seeks to solve]

However, in this type of heat fixing device, in order to maintain the surface temperature of the heat fixing roller at a temperature suitable for the object to be fixed, a temperature detection sensor detects the surface temperature and turns the heat source on and off. In this case, if a large heat source that generates heat is used to eliminate the temperature drop in the heat fixing roller caused by heat absorption by the toner and paper, the surface temperature fluctuation (ripple) due to the on/off of the f'8 source will increase. , the surface temperature may deviate from the appropriate surface temperature. Furthermore, if the amount of heat generated by the heat source is reduced in order to reduce the pull, the heat jlX necessary for continuous paper passing may not be obtained, and the fixing performance may be significantly reduced.

Furthermore, in order to shorten the time it takes for the heating and fixing roller to reach a predetermined temperature, if the heating needle of the heat source is made larger or the heat capacity of the heating and fixing roller is made smaller, ten-pern neat occurs. Laura temporarily becomes Il! There was also the risk of it getting too hot and being damaged. In addition, overheating is likely to occur in the non-sheet passing area, which is inconvenient.

In addition, a high-speed heat fixing device requires a heat source of 100% to compensate for heat dissipation during continuous use, but if a heat source with a large amount of heat generation 4) is used, the above-mentioned overshoot is likely to occur. Considering power supply capacity H and H1. +9. In this case, the maximum power consumption of the heat source is limited, and as a result, the continuous use time (number of copies) is limited,
This is inconvenient because it limits the fixing speed.

It is thought that most of the problems listed in I- are due to the following factors. In other words, the amount of heat removed from the surface of the heat-fixing roller is supplied directly from the heat source one after another. At this time, it takes a certain amount of time for the heat to reach the surface of the heat-fixing roller from the heat source. , the number of sheets that can be used continuously is limited depending on the amount of continuous heat generated.

The uninvented invention is a heat fixing system that eliminates the disadvantages of the conventional example, suppresses ripples and open neatness, keeps the surface temperature of the heat fixing roller constant, and exhibits stable fixing performance even at high speed fixing. The purpose is to provide JAW-ri.

Structure of the invention [L stage for solving the problem] Heat is applied to the heating fixing rotor, which contains a latent heat material that changes the phase change temperature near the optimum fixing temperature, and the latent heat storage material. A heat fixing device comprising a heat source for supplying heat, and a drive source for rotationally driving a rotating body of the heat fixing device and conveying an object to be fixed in contact with or in close proximity to the rotating body.

[For production]

The heat supplied from the heat source is stored in the latent heat storage material filled in the heat-fixing rotating body, and then transferred to the heat-fixing roller surface. Temperature fluctuations (ripples) on the surface of the heat fixing roller can be suppressed to a minimum. In other words, fluctuations in the amount of heat generated by the heat source are absorbed by the latent heat storage material that has a phase change temperature near the fixing n;ta temperature, and the surface +j'+L temperature of the heating and fixing roller is always kept at a predetermined optimum temperature, that is,
It becomes possible to maintain the heat radiation temperature near the same as that of the latent heat storage material, and stable fixing performance can be obtained.

In addition, it has become possible to store a large amount of heat at a predetermined temperature when not fixing, and then radiate the heat at a constant temperature during fixing.
A fixing device that has more stable fixing performance than conventional fixing devices and is capable of faster fixing can be obtained.

〔Example〕

One side is a cross-sectional view of an embodiment showing the basic configuration of the heat fixing device of the present invention. 1 is a hollow heating fixing roller, in which a fixed base cylinder 14 made of metal such as aluminum and a rotating base cylinder 12 are arranged concentrically inside and outside at a predetermined interval, and the interval space l , is filled with latent heat storage material 13. The roller surface is coated with a layer 11 of offset protection 11 made of Teflon or the like to prevent toner adhesion. 2 is the inner cylinder l
, l as a heat source, and is, for example, a halogen lamp. 4 is a thermistor for detecting the temperature on the circumferential surface of the heating and fixing roller 1; 5 is a recording material shadowing claw; 6 is a coating device for supplying offset prevention liquid to the roller surface; 7 is the heating roller 1; This is a pressure roller that rotates in pressure contact with the substrate, and is composed of a base cylinder 72 made of aluminum or the like and a adhesive layer 71 such as silicone rubber. 8 is a paper feed guide, P is recording paper, and T is toner.

The heating and fixing roller 1 is rotationally driven by a drive source (not shown), and the recording material P having the unfixed toner image T that has entered between the heating and fixing roller 1 and the pressurizing port 7 that comes into pressure contact with and follows the heating and fixing roller 1 is rotated between both rollers. The toner image is heated and fixed by being held and conveyed.

Since toner having an optimum fixing temperature of around 176°C is fixed on the wood flow side, a suitable material for the heat storage material 13 is Pentaerythri I.-L (C (CH70H)) disclosed in Japanese Patent Application No. 197356/1983. n). The latent heat due to the crystal transition of this substance is 322 kJ/kg. In other words, at low temperatures below the transition temperature of 188°C, molecules are strongly bound together by hydrogen bonds, whereas at high temperatures, hydrogen bonds are broken due to phase transition.
The degree of freedom of rotation of the carbon atom around the carbon atom occurs, and it has latent heat by causing a large entropy change. Moreover, it is a crystalline powder with a melting point of 262° C. as a pure substance and a specific gravity of 1.399. The thermal conductivity of this material is on the order of 10' W/m, which is 1/1 that of metal.
00 to about 1/1000, the heat transfer area may be increased or the substance may be mixed with a fluid in which it is insoluble, such as a hydrocarbon heat transfer oil.

In the example shown in the figure, a fluid heat storage medium containing oil and pentaerythritol mixed at a ratio of about 50% is applied to a metal base material.
Approximately 20 to 100% (20°
Volume ratio at C) was filled and sealed. The higher the ratio, the larger the heat storage capacity, but it is set in consideration of the stirring of the heat storage material and the internal pressure. 16 is provided on the inner surface of the outer cylinder 12 or has fins for heat radiation and stirring to promote heat transfer.

Gold 1ii heated by internal halogen heater 15
1; Pentaerythritol, which is the main heat storage body, absorbs heat through the inner cylinder 14 and is stored at 188°C. The stored pentaerythritol is effectively stirred by the fins 16 by the rotation of the outer cylinder 12 of the heat fixing roller l, and is moved away from the peripheral wall surface of the metal base inner cylinder l and onto the inner wall of the metal base outer cylinder 12. Moving. At this time, heat accumulated and the temperature reached 188°C. P7 erythritol radiates heat and supplies heat to the metal base outer cylinder 12, and the outer cylinder 12 is kept at an extremely stable temperature of 175 to 178°C (except when rising from a low temperature). In this case, the heat storage capacity ψ is a mixing ratio of 50%
It is about 150kJ/kg.

In an experimental example, in the case of a fixing object on which a resin toner image was formed on paper with an optimum fixing temperature of around 176°C, the temperature at which the heat can be extracted from pentaerythritol was 175°C to 175°C.
Since the temperature is 178° C., temperature control is not necessary except when starting up from a low temperature. After the fixing temperature is reached, it is sufficient to roughly control the heat source by periodically turning it on and off, or by generating heat for a predetermined period of time for - times of fixing.

This is possible because the heat generated from the heat source is not directly reflected in the roller surface temperature as in the conventional method, but instead the heat is stored in the heat storage material and then radiated at a constant temperature. It is also clear that the temperature of the non-sheet passing portion of the heat fixing roller hardly increases. .

Also, when fixing was performed continuously at high speed while not fixing, it was found that when the amount of heat generated by the heat source was the same, a conventional heated fixing roller of the same diameter was kept at 188°C, which is close to the upper limit of the optimum fixing temperature range. Therefore, compared to the number of sheets where the roller surface becomes below the minimum fixing temperature when performing high-speed continuous fixing, the fixing device of this embodiment can continuously fix a larger number of sheets at a stable temperature of 175 to 178°C. Ta. From this, it is clear that the fixing device of the present invention is capable of high-speed continuous fixing of a larger number of sheets than the conventional method without increasing the amount of heat generated by the heat source by storing heat when not fixing.

In the above embodiments, the heat storage material is mixed with oil in order to increase its fluidity, but pentaerythritol powder, which is a heat storage material, may be directly enclosed. However, in that case, it is necessary to strengthen the stirring mechanism.

A surfactant may be added to prevent the pentaerythritol powder from coagulating, and in order to prevent pentaerythritol crystals from adhering to the walls of the inner and outer cylinders 1 and 14, It may be coated with Teflon or the like.

Furthermore, the present invention is basically applicable to the heat-fixing rotating body not only in the roll state as shown in the drawings but also in the form of a belt.

In addition, in this embodiment, the optimum fixing temperature of the toner is 176
Although we have described an example of a latent heat storage material suitable for temperatures around °C, depending on the optimal fixing temperature of the toner, other latent heat storage materials may be used, for example, around 1 °C.
Urea, which undergoes a phase change at 30°C, high-density polyethylene, which undergoes a phase change at approximately 135°C, and N, which undergoes a phase change at approximately 170°C.
Alkali hydroxide eutectic degree l! such as a0H-KOH! etc.

C. As described in detail of the invention, a latent heat storage material that stores heat at a predetermined temperature and radiates heat near the optimum temperature for fixing is interposed between the heat source and the surface layer of the rotating body for heating and fixing, so that the surface of the rotating body is It is now possible to maintain a constant temperature, resulting in stable fixing performance.
1) It is possible to increase the speed. Again 1
It is possible to stir the heat storage material using the rotation of the rotating body.
It is f-noh.

A heat fixing device capable of effectively promoting heat transfer and having high thermal efficiency can be obtained.

[Brief explanation of the drawing]

The drawing is a cross-sectional view of one embodiment of the heat fixing device of the present invention. 1 is a heat-fixing rotating body, 13 is a heat storage material, 2 is a heat source, and 7 is a pressurizing rotating body.

Claims (1)

[Claims] (1) A heating fixing rotor containing a latent heat storage material having a phase change temperature near the optimum fixing temperature, a heat source for supplying heat to the latent heat storage material, and a heating fixing rotor that is rotatably driven. , and a drive source for conveying the object to be fixed in contact with or in close proximity to the surface thereof.