JPH06167856A - Fixing device - Google Patents

Abstract

PURPOSE:To provide the fixing device which can control the temp. of a fixing roller without providing a sensor and control circuit for exclusively use and makes a great contribution to saving of electric power consumption. CONSTITUTION:This fixing device fixes the toner image formed on a recording material 14 by respective means for forming, development and transferring an electrostatic latent image onto this recording material 14 and has a fixing heat source 23 for heating the fixing roller 20, a gas transporting means for introducing the ozone and NOx generated in the electrostatic latent image forming means and/or transferring means into the inside of the fixing roller 20 and a member which is arranged on the inner side of the fixing roller 20 and generates active oxygen and exothermic reaction. The members to be used are exemplified by decomposition accelerators and adsorbents such as, for example, fine powder platinum, manganese oxide, lead oxide, copper oxide and mercury. These members are preferably used by applying and depositing the members on a planar or fabric-like base in the form of increasing the contact area with the gas to be introduced by the gas transporting means.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus such as an electrophotographic copying machine and a printer.

[0002]

2. Description of the Related Art With the development of information processing technology, various image forming apparatuses such as copying machines and printers have been developed and put into practical use, and a typical one of them is an electrophotographic image forming apparatus.

In this electrophotographic system, for example, a photosensitive drum is charged by a corona discharger, and then the photosensitive drum is selectively exposed to form a desired electrostatic latent image. After developing the latent image with toner,
The toner image formed on the recording material is transferred to the recording material and is fixed to the recording material by heat or pressure.

It is known that in such an image forming apparatus, the quality of the finally formed image depends on the control accuracy of the heating temperature in the fixing step. In addition, the power consumed by the fixing device is usually as large as several hundreds of watts, which accounts for about 50% of the total power consumption of the copying machine and printer, so the temperature should be lowered during standby (non-fixing). We are trying to reduce power consumption. For example, in a typical electrophotographic popular printer, the temperature of the fixing roller of the fixing device is set to about 165 ° C during standby, the image signal is transferred, and the image forming process starts. The fixing heat source (heater) of the fixing device is controlled so that the temperature becomes about 185 ° C. That is, in the fixing device of the popular type printer, various sensors, in order to form a highly reliable image while coping with the economical problem of saving power consumption,
It was necessary to achieve proper temperature control of the fixing roller by performing strict timing control using a control circuit or the like.

[0005]

In the conventional fixing device as described above, in order to save power consumption, the temperature of the fixing roller is detected by a temperature sensor, and the electric power supplied to the heater of the fixing device is supplied by this signal. Since the method of controlling is adopted, there is inevitably a time lag. Therefore, it is necessary to control the timing with a time margin so that the recording material to be fixed is set to a required temperature when it is conveyed to the fixing roller. Moreover, since an excessive amount of power is supplied immediately after changing the temperature setting, an overshoot phenomenon occurs in which the temperature of the fixing roller exceeds the set temperature. Then, when the recording material is supplied to the fixing device at this time, there is a problem in that the melted toner remains on the surface of the fixing roller that is excessively heated, and a false image matching the peripheral length of the fixing roller is fixed. It was

Further, in the above-mentioned electrophotographic popular printer, ozone and nitrogen oxides, which have many safety and health problems at the charging stage of the photosensitive drum by a corona discharger, are generated.
So, for example, through a filter with a heater,
Although it adopts a configuration that exhausts air containing ozone and nitrogen oxides, the addition of a heater here leads to further increase in power consumption and excessive heat dissipation, which causes economic or environmental problems. Will be raised.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and it is possible to control the temperature of the fixing roller without providing a sensor and a control circuit.
It is an object of the present invention to provide a fixing device that greatly contributes to the reduction of power consumption.

[0008]

A fixing device according to the present invention is a fixing device for fixing a toner image formed on a recording material by means of electrostatic latent image formation, development and transfer to the recording material. A fixing heat source for heating the fixing roller; a gas transporting means for guiding ozone and nitrogen oxides generated by the electrostatic latent image forming means and / or the transferring means to the inside of the fixing roller; It is characterized in that it has a member that is disposed inside and that causes an exothermic reaction with active oxygen.

Examples of the member used in the present invention include fine powder platinum, manganese oxide, lead oxide, copper oxide, decomposition accelerators such as silver and mercury, and adsorbents.
Further, it is preferable that these members are applied / adhered to a plate-shaped or cloth-shaped support surface and used in a form in which the contact area with the gas guided by the gas transport means is increased.

[0010]

In the fixing device of the present invention, ozone and nitrogen oxides generated in the image forming process are guided to the inside of the fixing roller by the gas transportation means, and the ozone and nitrogen oxides are decomposed by the heat from the fixing heat source. The active oxygen generated by the reaction reacts with the member disposed inside the fixing roller. Since the temperature of the fixing roller rises due to the heat generated by this chemical reaction, the temperature of the fixing roller can be controlled without increasing the electric power supplied to the fixing heat source.

[0011]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

First, the structure of the image forming apparatus will be described with reference to FIG. In FIG. 2, the photoconductor drum 1 is rotatably provided in the direction of arrow A in the substantially central portion of the image forming apparatus. Here, the photoconductor drum 1 is formed of, for example, an organic photoconductor (OPC) -based photoconductive material, and the diameter of the photoconductor drum 1 is, for example, 40 μm.
mm. Further, around the photoconductor drum 1, along with its rotation direction, a charge eliminating unit 2 for removing the charge on the surface of the photoconductor drum 1, and a transfer residual toner remaining on the surface of the photoconductor drum 1 after transfer are agitated. A stirring unit 3, a scorotron charger 4 for charging the surface of the photosensitive drum 1, an electrostatic latent image forming unit 5 for forming a required electrostatic latent image on the surface of the photosensitive drum 1, and a developing device 6 having a cleaning simultaneous cleaning function. A transfer roller 7 that transfers the toner image onto the recording material 14 is sequentially arranged.

In the image forming apparatus, the required recording material 14 is provided in the transfer area between the photosensitive drum 1 and the transfer roller 7.
A paper feed roller 16 is provided as means for conveying and supplying the paper from the paper feed unit 15. That is, the recording material 14 such as plain paper or plastic film is fed from the paper feeding unit 15 to the transfer area in synchronization with the rotation of the photosensitive drum 1. A bias voltage having a positive bias is applied to the back surface of the recording material 14 by the transfer roller 7, and the toner image on the surface of the photosensitive drum 1 is electrostatically attracted to the surface of the recording material 14 and transferred. It has a structure. Then, the recording material 14 to which the toner image is transferred is conveyed along the conveyance guide 17 between the fixing roller 20 of the fixing device 18 and the pressure roller 22, and the toner image is permanently fixed by the fixing device 18 and discharged. It is ejected to the outside of the fixing device 18 by the roller 19.

In the present invention, in the fixing device 18 used in the image forming apparatus having such a basic structure, the fixing roller 20 is formed in a cylindrical shape, and the active oxygen and the exothermic reaction are generated inside the fixing roller 20. While arranging the resulting member, a gas transportation means 21 for conveying the air containing ozone and nitrogen oxides generated by corona discharge in the image forming apparatus to the region where the member is disposed is provided with ozone and nitrogen oxides. The heat of chemical reaction between the active oxygen and the member generated by the thermal decomposition of the is used for controlling the temperature of the fixing roller 20. FIG. 1 is a perspective view showing the configuration of the main part of such a fixing device 18, in which a pressure roller 22 is arranged so as to face the fixing roller 20, and further, the fixing roller 20.
A heater 23 as a heat source for fixing is inserted and disposed inside of the above, and the member (not shown) is arranged.

Next, the operations of the image forming apparatus and the fixing device having the above-mentioned configurations will be described.

First, the negative charging type photosensitive drum 1 is attached to the arrow A.
The peripheral surface of the photoconductor drum 1 is negatively charged by the scorotron charger 4 by rotating in a direction. Then, according to image information, a light beam 8 is emitted from the electrostatic latent image forming means 5 composed of, for example, EEH (EL edge emitter array head) to the charged area on the peripheral surface of the photosensitive drum 1 by the scorotron charger 4. Irradiation and exposure are performed to form a required electrostatic latent image on the surface of the photosensitive drum 1. Although EEH is used as the electrostatic latent image forming means 5 in this embodiment, there is no problem even if a laser, an LED, a liquid crystal shutter or the like is used.

The area on the surface of the photosensitive drum 1 where the electrostatic latent image is formed is conveyed to the developing area facing the developing device 6 and developed by the developing roller 9. At this time, in the developing unit, the triboelectrically-charged so-called one-component toner 11 contained in the hopper 10 moves from the back roller 9 onto the photosensitive drum 1 for development, and at the same time, in the non-image portion. Then, the transfer residual toner remaining on the photosensitive drum 1 is moved to the developing roller 9 side and cleaning is performed.

An elastic blade 12 is pressed against the developing roller 9, and the toner 11 passing through the developing roller 9 is negatively triboelectrically charged with the same polarity as that of the photosensitive drum 1, and the first to third layers.
A toner layer having a layer thickness is formed on the surface of the developing roller 9. Further, the developing roller 9 has a bias power source (not shown).
Is connected, which constitutes a structure for applying a predetermined developing bias at the time of simultaneous developing cleaning.
Further, a toner conveying roller 13 is provided in the hopper 10 to prevent aggregation of the toner 11 in the hopper 10 and
Plays the role of transportation supply. Then, the toner 11 is sent out from the developing roller 9 of the developing device 6, and comes into contact with the electrostatic latent image formed on the surface of the photosensitive drum 1 elastically and with a nip width by deformation, Toner 11
Is attached to the surface of the photosensitive drum 1 on which the electrostatic latent image is formed to form a toner image. In this case, the toner 11 adheres to the light irradiation area and undergoes reversal development. That is, the toner 11 is
Due to friction between the elastic blade 12 and the developing roller 9, the developing roller 9 is charged to about −5 to −30 μc / g, and a developing bias is applied to the developing roller 9 to perform required reversal development.
The surface of the photosensitive drum 1 on which the toner image is formed by such reversal development is then conveyed to the transfer area facing the transfer roller 7. A recording material 16 such as plain paper or a plastic film is sent from the paper feeding unit 15 to the transfer area by the rotation of the paper feeding roller 14 in synchronization with the rotation of the photosensitive drum 1. Here, a bias voltage biased to the positive polarity is applied to the back surface of the recording material 16 by the transfer roller 7, and the toner image on the surface of the photosensitive drum 1 is
It is electrostatically attracted to the surface of the recording material 16 and transferred. The recording material 16 on which the toner image has been transferred is conveyed along a conveyance guide 17, and the toner image is permanently fixed by a fixing device 18,
The sheet is discharged to the outside of the fixing device 18 by the discharge roller 19. on the other hand,
After the transfer of the toner image to the recording material 16, the photosensitive drum 1 passes through the discharging unit 2 with the transfer residual toner remaining on the surface thereof, and the electrostatic latent image on the surface of the photosensitive drum 1 is mostly discharged. It Further, the conductive brush 3a provided in the agent stirring means 3
However, the photosensitive drum 1 is rubbed with the rotation of the photosensitive drum 1 to sufficiently stir and unpattern the untransferred toner. in this way,
After the electrostatic latent image is erased and the untransferred toner is unpatterned, the surface of the photosensitive drum 1 is charged to a predetermined potential by the scorotron charger 4. At this time, the untransferred toner that has not been patterned on the surface of the photosensitive drum 1 and is uniformly scattered is also charged, and is cleaned in the developing device 6 at the time of development, and the above steps are repeated.

On the other hand, in the fixing device 18, the heater 23 is inserted and fixed to the cylindrical fixing roller 20.
The fixing roller 20 and the pressure roller 22 rotate in the direction shown by the arrow in FIG. 1, and the toner image transferred onto the recording material 14 conveyed in the direction of arrow B in the figure along the conveying guide 17 as described above. To be permanently fixed. Here, the air containing ozone and nitrogen oxides generated in the vicinity of the scorotron charger 4 of the image forming apparatus is guided to the inside of the fixing roller 20 via the gas transporting means 21, and enters the inside of the fixing roller 20. After gathering around the heaters 23 fixed by insertion and finishing a desired reaction, they are discharged to the outside of the housing through an air blower and a filter. At this time, inside the fixing roller 20, active oxygen generated by decomposition of ozone and nitrogen oxides due to the heat of the heater 23 reacts with a member arranged inside the fixing roller 20 to generate heat. That is, the air containing ozone and nitrogen oxides generated from the scorotron charger 4 used in the electrophotographic image forming process is introduced into the fixing roller 20 by the gas transporting means 21. At this time, in the fixing roller 20, the heating heater 23 is used as the fixing heat source and 400 ° C to 450 ° C when the temperature is controlled at 160 ° C during the print standby.
The radiant heat from the tube wall of the heater 23 at ℃
Conducted on the inner surface of 20. As a result, ozone and nitrogen oxides in the air, which have been induced inside the fixing roller 20, pass through the space between the heater 23 and the fixing roller 20 and are instantaneously heated by high heat of 400 ° C. or more (0.1 sec. (It is known that more than 99% of ozone decomposes in 0.1 sec at 300 ° C). Therefore, for example, in the ozone, air containing oxygen molecules and active oxygen or ozone products is decomposed into oxygen molecules and active oxygen. Among them, the active oxygen is the air of the fixing heater 23 and the inner surface of the fixing roller 20. Floating in the space, in particular, active oxygen, together with the active oxygen generated by the decomposition of nitrogen oxides, is applied to the inner surface of the fixing roller 20 and easily reacts with a member that causes an exothermic reaction to generate reaction heat. Then, the fixing roller 20 is heated. In this way, the air containing ozone and nitrogen oxides generated from the scorotron charger 4 and the like is surely rendered harmless, and is discharged to the outside of the housing by the air blower, while the fixing device is operated during the image forming process. The temperature of the fixing roller 20 of 18 rises. In this example, when the inner surface of the fixing roller 20 was coated with, for example, a silver-palladium alloy-based adsorbent as the member, the temperature rise due to the exothermic reaction between active oxygen and the member was about 20 ° C.

In the above embodiments, a silver-palladium alloy is used as a member that causes an exothermic reaction with active oxygen. However, in the present invention, such a member should be appropriately selected according to target values such as the amount of heat generated and the life. When decomposing the ozone and nitrogen oxides, an electrostatic decomposing means can be used in addition to the thermal decomposition shown in the examples.

Further, in the above-described embodiment, the structure in which the air containing ozone and nitrogen oxides generated at the time of charging the photoconductor drum 1 is guided to the inside of the fixing roller 20 has been described. When ozone or nitrogen oxides are generated by corona discharge in the transfer process in the configuration using the transfer device, the air containing the ozone or nitrogen oxides generated here is used in the fixing roller 20 in the same manner as in the case of the above example. Just lead it inside.

The fixing device according to the present invention is not limited to the above-mentioned constitution, but may be appropriately modified without departing from the gist of the invention. For example, the arrangement of the gas transportation means, the arrangement state of the members, the combined use of two or more kinds of the members, and the like can be appropriately selected and set according to the design of the fixing device or the image forming apparatus and the use conditions.

[0023]

As described above, according to the fixing device of the present invention, ozone and nitrogen oxides generated in the image forming process are guided to the inside of the cylindrical fixing roller to remove ozone and nitrogen oxides. The active oxygen generated by the decomposition reacts with the member arranged inside the fixing roller, and the reaction heat generated at this time is effectively used. Therefore, without increasing the electric power supplied to the heater, the temperature of the fixing roller is controlled by the heat generated by the reaction so that the temperature of the fixing roller is raised and the desired fixing temperature can be maintained and exhibited. You can

As described above, in the fixing device according to the present invention, it is not necessary to increase the electric power supplied to the heater when the image forming process is in operation, which greatly contributes to the reduction of the electric power consumption. Moreover, it is possible to easily bring the fixing roller to the desired temperature in synchronization with the image forming process of the image forming apparatus without timing control using a dedicated control circuit and sensor.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration example of a main part of a fixing device according to the present invention applied to an image forming apparatus.

FIG. 2 is a cross-sectional view showing a schematic configuration example of an image forming apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Static elimination means 3 ... Stirring means
3a ... Conductive brush 4 ... Scorotron charger 5 ... Electrostatic latent image forming means
6 ... Developing device 7 ... Transfer roller 8 ... Light beam
9 ... Developing roller 10 ... Hopper 11 ... Toner 12 ...
Elastic blade 13 ... Toner conveying means 14 ... Recording material
15 ... Paper feeding unit 16 ... Paper feeding roller 17 ... Conveying guide 18 ... Fixing device 19 ... Discharging roller 20 ... Fixing roller 21 ... Gas transporting means 22 ... Pressure roller 23
… Heating heater

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kenichi Mori, 1 Komukai Toshiba-cho, Sachi-ku, Kawasaki-shi, Kanagawa, Ltd. Within Toshiba Research Laboratories, Inc. (72) Inventor Mitsunori Saito, Komukai Toshiba Town No. 1 Incorporated company Toshiba Research Institute (72) Inventor Norihiro Osugi 6-78 Minamimachi, Mishima City, Shizuoka Prefecture

Claims (1)

[Claims] 1. A fixing device for fixing a toner image formed on a recording material by means of electrostatic latent image formation, development and transfer to the recording material, and a fixing heat source for heating the fixing roller. A gas transporting means for guiding ozone and nitrogen oxides generated in the electrostatic latent image forming means and / or the transferring means to the inside of the fixing roller, and a member arranged inside the fixing roller to generate an exothermic reaction with active oxygen. And a fixing device.