JPH06175511A - Toner fixing device for electrophotography and the like - Google Patents

Abstract

PURPOSE:To ensure fixing, to carry out the transfer speedily and to shorten warm-up time. CONSTITUTION:A PTC ceramic heater 1 for heating toner, which is in the form of a plate in order to reduce heat capacity to the lowest degree possible, is held on a heat-resistant support in order to suppress heat loss, and it is provided with a heat transfer plate serving also as an electrode, which is made of a material with good thermal conductivity, such as Al. An endless belt sheet 2 is provided on the heater 1, and means 3 and 4 for carrying a recording material 5 running on the endless belt sheet 2 are further provided. A toner image transferred to the surface of the recording material 5 is melted and fixed by being heated from the back of the recording material 5. The endless belt sheet 2 is in contact with the top of the heater 1 in such a manner that tension is not applied thereto, and can move in the direction in which the recording material 5 advances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner fixing device for electrostatic printing, electrophotography and the like.

[0002]

2. Description of the Related Art In conventional processes such as electrostatic printing and electrophotography, toner is finally fixed and fixed on a print medium such as paper in the order of development, transfer and fixing. In the heat fixing roller in this fixing device, a halogen lamp is used as a toner heating source, and a temperature control circuit using a thermistor or the like is provided to control the temperature at a constant level. More recently, for example, in Japanese Unexamined Patent Publication No. 1-21078 (known example A), the toner heating and fixing roller main body itself is formed of a ceramic infrared heater or the like, Japanese Patent Publication No. 64-417.
Japanese Unexamined Patent Publication No. 6 (Publication B) discloses a PTC ceramic dispersed in a binder such as glass for facilitating the processing.

[0003]

However, the above-mentioned conventional fixing device has the following problems. (A) In the fixing device having the process of fixing the toner on the recording material in the order of development, transfer and fixing, there is a space limit in achieving miniaturization. (B) In the case of using a halogen lamp as a toner heating source, heat radiation efficiency is poor because heat radiation is used as a means for transmitting heat to the toner heating and fixing roller main body, so that the toner is heated after the power of the fixing device is turned on. There is a problem that the time required for the surface of the fixing roller main body to reach a predetermined temperature (hereinafter referred to as warm-up time) is long, resulting in a large power loss. (C) Further, in the above-mentioned known example A, precision processing such as crown processing on the surface of the fixing roller is difficult, dimension control is difficult, and the processing cost is high. (D) In the above-mentioned known example B, since the binder is used, PT
The fixing property of the toner may be deteriorated due to the deterioration of the C characteristic or the like.

The object of the present invention is to solve the above problems.
It is an object of the present invention to provide a new process for simultaneously performing the transfer and fixing processes and a fixing device capable of significantly reducing the warm-up time.

[0005]

In order to achieve the above object, a first invention of the present invention is to provide a toner fixing device equipped with electrophotographic, electrostatic printing and other developing, transferring and fixing means.
Provide an endless belt-like sheet on the heater for heating the toner,
A means for transporting the recording material running on the endless belt-shaped sheet is provided, and the toner image transferred on the recording material is heated and fixed by the toner heating heater via the endless belt-shaped sheet. The belt-shaped sheet is a toner fixing device for electrophotography or the like, which is in contact with the heater for heating the toner so as not to apply tension, and is movable in the traveling direction of the recording material. In a toner fixing device equipped with printing, development, transfer, and fixing means, an endless belt-shaped sheet is provided on a heater for heating toner, and a transfer means for a recording material running on the endless belt-shaped sheet is provided. Toner fixing for electrophotography, etc., in which a drum-shaped photosensitive member with toner developed is provided at a position facing the heater for heating the toner through a sheet and a recording material. A third aspect of the invention is a toner fixing device for electrophotography, in which a heater for heating a toner and a drum-shaped photoreceptor are in contact with each other via an endless belt-shaped sheet and a recording material, and a fourth invention. Is a toner fixing device for electrophotography or the like in which a gap is provided between the endless belt-shaped sheet and the drum-shaped photosensitive member.

The fifth invention is a fixing device in which the heater for heating the toner is a plate heater made of a PTC material (a material having a positive temperature coefficient) having a self-temperature control function at a predetermined temperature.

[0007]

In the first aspect of the present invention, unlike the conventional heat fixing roller, the toner heating heater is provided below the running recording material, and the endless belt-like sheet is provided on the toner heating heater. The heat is transferred from the back surface side of the recording material via the endless belt-like sheet, and the transferred toner image can be reliably fused and fixed. The endless belt-shaped sheet comes into contact with the toner heating heater without tension and is movable in the moving direction of the recording material.When the recording material is transferred by the transfer means, the endless belt-shaped sheet advances. As the recording material moves in the direction, the recording material slides on the surface of the heater for heating the toner, and the fixing and fixing to the recording material due to the rush into the fixing device and the heating and melting of the toner are stably performed.

The second invention, the third invention and the fourth invention are
Since the drum-shaped photoconductor in which the toner is developed is provided through the endless belt-shaped sheet and the recording material at a position facing the heater for heating the toner, the transfer and the fixing of the toner image to the recording material are simultaneously performed at the same position. I was able to do it. Therefore, when the recording material is transferred by the transfer means, the drum-shaped photoconductor transfers the toner onto the surface of the recording material, and at the same time, the toner heating heater transfers heat from the back surface of the recording material to heat the toner. Fix it. Since the endless belt-shaped sheet on the heater for heating the toner moves in the traveling direction of the recording material, the heat fixing of the toner on the recording material can be stably performed as in the first invention.

According to the third aspect of the invention, since the heater for heating the toner and the drum-shaped photosensitive member are brought into contact with each other via the endless belt-shaped sheet and the recording material, the heat of the heater for heating the toner is efficiently transferred to the toner of the recording material. The toner can be accurately transferred onto the recording material from the drum-shaped photosensitive member. In the fourth aspect of the invention, the drum-shaped photoconductor is separated from the endless belt-shaped sheet, but the transfer of the toner from the drum-shaped photoconductor to the recording material, the movement of the recording material, and the heat fixing by the toner heating heater are synchronized. As a result, accurate transfer and fixing are stably performed.

In the fifth aspect of the invention, since the heater for heating the toner is a plate heater made of PTC material, the heat capacity can be reduced, and as a result, the surface of the heater for heating the toner can be brought to a predetermined temperature in a short time. In addition, the temperature can be maintained without the temperature control circuit.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A toner fixing device for electrophotography and the like shown as an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, 1 is a heater for heating toner, 2 is an endless belt-shaped sheet, and the shape thereof is cylindrical, and contact is made on the heater for heating toner 1 so that tension is not applied,
It is provided so as to be movable in the traveling direction of the recording material. The endless belt-shaped sheet 2 is made of a fluorine resin such as PFA or PTFE, an organic material such as polyamide or polyimide, or a heat-resistant material such as metal.

Reference numerals 3 and 4 are tension rollers as a transfer means, and 5 is a recording material.
Thus, the toner is heated on the heater 1 for heating the toner. Reference numeral 6 denotes a drum-shaped photosensitive member on which toner has been developed, which is provided at a position facing the heater 1 for heating the toner, with the endless belt-shaped sheet 2 and the recording material 5 interposed therebetween. Further, 7 is a charger, which is fixed to the toner heating heater side in the drum-shaped photoreceptor 6. The drum-shaped photoconductor 6 forms a closed circuit for passing a photocurrent at the time of exposure, but in order to form a potential difference on the inner surface of the drum-shaped photoconductor 6 by giving an electric charge from the charger 7, the transfer corotron. At the time of operation, a circuit that cuts the closed circuit is set. Reference numeral 8 denotes a toner. Regarding this toner property, the surface energy at the time of melting may be adjusted so that the viscoelastic property of the binder is adjusted so that the binder is melted and fixed on the recording material and fixed.

In the toner fixing device of this embodiment, the recording material 5
Since the endless belt-shaped sheet 2 is allowed to move in the traveling direction of the recording material when traveling on the heater 1 for heating the toner by the tension rollers 3 and 4, the stable traveling of the recording material 5 can be obtained. Therefore, there is no drum-shaped photoconductor 6 at a position facing the toner heating heater 1, and when the toner image is separately transferred onto the recording material 5, or the drum-shaped photoconductor 6 faces the toner heating heater 1. Even if they are far apart, stable running of the recording material 5 and fixing by heating and melting the toner can be realized.

When the heater 1 for heating the toner is in contact with the endless belt-shaped sheet 2 and the recording material 5, the friction coefficient μ1 between the heater 1 for heating the toner and the endless belt-shaped sheet 2 is 2 and the recording material 5 friction coefficient μ2, and the drum-shaped photoconductor 6 and the recording material 5 friction coefficient μ3
If it is set to be smaller than that, stable running of the recording material 5 can be obtained.

Specifically, the lubricant on the surface of the heater 1 for heating the toner, the surface smoothness of the front and back surfaces of the endless belt-shaped sheet 2, and the surface material of the drum-shaped photosensitive member 6 have a relationship of μ3>μ2> μ1. Is set to. Therefore, by setting the friction coefficient in this way, stable running of the recording material 5 can be ensured, and good fixing can be performed without rubbing the toner surface. The material of the endless belt-shaped sheet is not particularly limited, such as a metal foil or a film, and may be any material that satisfies the above conditions.

In the embodiment shown in FIG. 1, the toner heating heater 1 and the drum-shaped photosensitive member 6 are in contact with each other via the endless belt-shaped sheet 2 and the recording material 5. Therefore, when the recording material 5 is transferred by the tension rollers 3 and 4, the charger 7 fixed in the drum-shaped photoconductor 6 gives a charge of the same polarity as the toner 8 to separate the toner 8, and the recording is performed. Accurately transfer to the surface of the material 5. At the same time, the toner heating heater 1 efficiently transfers heat from the back surface of the recording material 5 to the toner 8 via the endless belt-shaped sheet 2, and the toner 8
Is melted by heating and fixed on the surface of the recording material 5.

FIG. 2 shows another embodiment, in which a gap is provided between the endless belt-shaped sheet 2 and the drum-shaped photosensitive member 6. FIG. 3 is an enlarged cross-sectional view of the toner heating heater 1 used in the fixing device shown in FIGS. 1 and 2. The toner heating heater 1 has a plate-shaped PTC ceramic heater. Reference numeral 9 is a support for the heater for heating the toner, and the support 9 is made of a heat-resistant resin such as PPS (polyphenylene sulfite) or a metal. 10 is a PTC ceramic heater. 11 and 12 are electrodes, P
The electrodes 11 and 12 are provided above and below the TC ceramic heater 10, respectively, and are made of a conductive material having good thermal conductivity such as Al. Further, the PTC ceramic heater 10 and the electrode 11 and the PTC ceramic heater 10 and the electrode 12 are joined by a conductive adhesive 13.

The surface of the electrode 11 is made of PFA (tetrafluoroethylene resin) in order to improve the sliding property with the endless belt-like sheet.
Such as lubricant 14 is coated. Also, the electrodes 11, 12
The material, method of taking, etc. are not limited to this example. Furthermore, when the PTC ceramic heater 10 is represented by a chemical formula,
Ba1-XPbXTiO3 (X = 0.01 to 0.3), and the PTC characteristic is adjusted so that the surface temperature of the heater 1 for heating the toner becomes 180 ° C. ± 5 ° C. when a voltage is applied. Further, the PTC ceramic heater 10 and the supporting base 9 are fixed to each other by using a non-heat conductive heat resistant adhesive. Incidentally, PT
The heat generation temperature of the C ceramic heater 10 may be adjusted by adjusting the PTC characteristic according to the melting temperature of the toner.

Using the PTC ceramic heater 10 shown in FIG. 3, the temperature control circuit was removed, and the warm-up time and the surface temperature distribution of the toner heating heater 1 were tested. As a test method, as shown in FIG. 4, a thermocouple 15 is provided at five points A to E of the toner heating heater 1.
Attach A to 15E, power supply for PTC ceramic heater 16
(AC100V) was turned on and the time-dependent change in the temperature of each part was recorded by a recorder. This record is shown in Table 1.

[0020]

[Table 1]

As can be seen from Table 1 above, since the PTC ceramic heater 10 has a heat capacity as small as possible, the warm-up time is about 4 seconds as compared with the conventional fixing device using a xenon lamp, which is greatly reduced. ing. In addition, the temperature of the surface of the heater for heating the toner is uniformly maintained at a predetermined temperature without unevenness.

Further, the toner fixing device for electrophotography shown in FIG. 1 is mounted on a laser beam printer (KX-P4450 manufactured by Matsushita Electric Industrial Co., Ltd.) with some modifications such as the temperature control circuit removed for continuous printing. The test was conducted. The test is low temperature / low humidity (10 ℃ / 20% RH), normal temperature / normal humidity (20 ℃)
/ 60% RH), high temperature / high humidity (32.5 ° C / 80% R)
Under each environment of H), the process was repeated up to 100,000 sheets, but in all cases, phenomena such as hot offset, cold offset, and uneven fixing were not observed, and good fixability was exhibited.

As described above, according to the present embodiment, the warm-up time can be greatly shortened as is apparent from Table 1. Further, the surface of the heater for heating the toner can be uniformly maintained at a desired temperature without using a temperature control circuit. In addition, the temperature hardly changes with time, and good fixability can be obtained even in the continuous printing test. Furthermore, since the PTC ceramic heater has a great degree of freedom in dimensional accuracy, the processing cost can be reduced.

[0024]

As described above, according to the first aspect of the present invention, since the endless belt-shaped sheet which is in contact with the heater for heating the toner so as not to apply tension and is movable in the traveling direction of the recording material is provided, the transfer is performed. The stable running of the recording material by the means and the heat from the heater for heating the toner can be reliably transmitted from the back side of the recording material through the endless belt-like sheet, and the toner can be melted and fixed reliably and quickly. It has also become possible to shorten the uptime.

The second invention, the third invention and the fourth invention are
Since the drum-shaped photosensitive member on which the toner is developed is provided at a position facing the heater for heating the toner via the endless belt-shaped sheet and the recording material, the phenomenon, transfer, and fixing, which are processes of the conventional electrophotography, can be performed. Instead of a step-by-step process,
It has become possible to provide a new process in which transfer and fixing are performed simultaneously, and as a result, it has become possible to realize downsizing of the toner fixing device.

In the third aspect of the invention, since the heater for heating the toner and the drum-shaped photoconductor are brought into contact with each other through the endless belt-shaped sheet and the recording material, the toner can be accurately transferred from the drum-shaped photoconductor. The heat of the heater for heating the toner was efficiently transferred to the toner on the recording material, and the fixing time of the toner could be further shortened. Furthermore, in the fifth aspect of the invention, the heater for heating the toner is a plate heater made of a PTC material, and the heat capacity is made as small as possible, so that the warm-up time can be greatly shortened compared to the conventional one. Moreover, the surface of the heater for heating the toner can be uniformly maintained at a desired temperature without using a temperature control circuit, and even in continuous printing, good fixing property without fixing unevenness can be obtained. A toner fixing device could be provided.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a toner fixing device for electrophotography showing an embodiment of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the toner fixing device.

FIG. 3 is an enlarged sectional view of a toner heating heater used in a toner fixing device.

FIG. 4 is an explanatory view of a main part of an apparatus for performing a temperature rising characteristic test of a heater for heating a toner.

[Explanation of symbols]

 1 Heater for heating toner 2 Endless belt-shaped sheet 3, 4 Transfer means 5 Recording material 6 Drum-shaped photoconductor 8 Toner

Claims (5)

[Claims] 1. Electrophotography, electrostatic printing and other development, transfer,
In a toner fixing device having a fixing means, an endless belt-shaped sheet is provided on a heater for heating a toner, and a recording material transfer means for traveling on the endless belt-shaped sheet is provided, and a toner image transferred onto the recording material is provided. Through the endless belt-shaped sheet is heated and fixed by the heater for heating the toner, the endless belt-shaped sheet is contacted without tension on the heater for heating the toner,
A toner fixing device for electrophotography or the like, which is movable in the traveling direction of the recording material. 2. Electrophotography, electrostatic printing and other development, transfer,
In a toner fixing device provided with a fixing means, an endless belt-shaped sheet is provided on a heater for heating toner, and a recording material transfer means for traveling on the endless belt-shaped sheet is provided, and the endless belt-shaped sheet and the recording material are interposed. A toner fixing device for electrophotography or the like, wherein a drum-shaped photosensitive member on which toner is developed is provided at a position facing the heater for heating the toner. 3. The toner fixing device for electrophotography according to claim 2, wherein the heater for heating the toner and the drum-shaped photosensitive member are in contact with each other via the endless belt-shaped sheet and the recording material. 4. The toner fixing device for electrophotography according to claim 2, wherein a gap is provided between the endless belt-shaped sheet and the drum-shaped photosensitive member. 5. A PTC in which the heater for heating the toner has a self-temperature control function at a predetermined temperature according to the melting temperature of the toner.
The toner fixing device for electrophotography according to claim 3 or 4, which is a plate heater made of a material (a material having a positive temperature coefficient).