JPS63187274A - Heating fixing roller - Google Patents

Abstract

PURPOSE:To prevent the contact failure of a contact, and also, to improve the durability by forming a ring-like electrode for supplying power to the heating layer of the surface of a ceramic core, by a metal coating method. CONSTITUTION:Cylindrical electrodes 5, 5a are formed by applying and contacting a suspension mixing a corpuscular electrode material into an electric insulating medium, to the prescribed position of a ceramic roller base material, applying a high voltage by inserting a pair of ring-shaped electrodes, and coating the electrode material to the ceramic surface part between the pair of electrodes, connected to the heating layer 3 of the periphery of a ceramic core 2 by conductors 6, 6a, and connected to conductors 8, 82 from a power source through sliding bearings 7, 7a. By the formation of these cylindrical electrodes 5, 5a, a firm metal coated film is formed on the ceramic roller core 2, and a heating fixing roller being stable at the lapse of time and having high reliability is obtained.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a heating fixing roll used in equipment using an electrophotographic process such as an electrophotographic copying machine, a facsimile machine, and a printer, in particular a heating layer on the surface of a ceramic core. The present invention relates to an electrode portion that supplies power to a heat generating layer of a heat fixing roll formed with a heat fixing roll.

``Prior Art'' In an electrophotographic process, a toner image formed on a photoreceptor is generally transferred onto a recording support, such as paper, by a transfer device, and then, if necessary, the toner image is fixed on the surface of the paper to create a desired image. Copy etc. (q).

As methods for fixing toner images, heat fixing methods, pressure fixing methods, and solvent fixing methods are known.

The heat fixing method is a method in which toner is melted by heating and adhered to paper, and is widely adopted.

There are various heat fixing methods, such as a hot air fixing method, an oven fixing method, and a heated roll fixing method, but the heated roll fixing method is the most common.

The heating roll method that has been commonly used for a long time
As shown in FIG. 4, the apparatus consists of a heating roll 1a and a pressure roll 10a, and the paper 20 is conveyed while being held between the heating roll 1a, which houses an internal heating element 25 therein, and the pressure roll 10a. At this time, heating and pressure are applied to fix the unfixed toner image 21 on the surface of the paper 20 transferred from the photosensitive drum.

In a heating roll type fixing device using such an internal heating element 25, a lamp such as a halogen lamp is used as the heating element (heat source), but the surface temperature of the roll is kept at a constant temperature necessary for heat fixing. In order to raise the temperature to
It requires about 10 minutes of setup time. Therefore, after the operator turns on the switch, the Δ
- There was a loss of time during which the copy operation could not be performed until the system was updated.

Therefore, as a method to eliminate the drawbacks of the heating roll type fixing device, a heating layer is recently formed on the circumferential surface of the support roll.
A heating roll provided with a release layer on its surface has been proposed (Utility Model Application Publication No. 58-172952, etc.). With this method, it is not necessary to heat the entire roller in order to raise the roll surface temperature to a predetermined temperature, so the warm-up time can be shortened.

Examples of rolls with a heat generating layer include those in which a heat generating layer is provided on the surface of a ceramic roll core, those in which a sheathed heater is wound around a metal core, or those in which a metal core is covered with an insulated thin film heating element. is proposed.

[Problems to be Solved by the Invention] However, in all of these systems, the heating element is integrated with the roll, and the heating element also rotates as the roll rotates. There is. Therefore, it is impossible to directly connect the electric wire that supplies power to the heating element, and it is necessary to supply power using an electrical contact that can tolerate slippage, such as a slip ring or brush electrode. (Unexamined Japanese Patent Publication No. 58-21794, etc.)
.

However, the power supplied to the heating roll of a copying machine is extremely large, at 500 to 1000 watts, even in a small copying machine, and the current flowing through the contacts must be as large as 5 to 10 amperes at a voltage of 100 volts. It is said that

Furthermore, since the surface temperature of the heating roll is as high as 150 to 200 degrees Celsius, if the contact point is placed far away from the heating part, as in the conventional heating method using a lamp, there will be no conduction from the heating part. However, in the above-mentioned devices, where the contacts must be placed close to the heating part, the electrical contacts may be damaged due to the high temperature, or may be damaged due to poor contact or abrasion of the contacts. Sufficient power supply may not be provided.

In addition to the above-mentioned disadvantages, spark discharge and the like may occur, which causes abnormal operation of control devices for other parts of the copying machine, causing malfunctions and failures of other parts.

Conventionally, copper-based alloys are often used as materials for cylindrical electrodes that allow for slippage, but when using a ceramic core, mounting by the shrink fit method is difficult due to the difference in linear expansion coefficient between the two materials. This was not possible due to the strength of the ceramic core. The method of attaching a cylindrical electrode ring using a conductive agent also has the disadvantage that the adhesive strength becomes insufficient over time due to the influence of heat, making it unusable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned disadvantages and to provide a heat fixing roll having a heat generating layer formed on the surface of a ceramic core, in which a ring-shaped electrode for supplying power to the heat generating layer is covered with a strong metal. The objective is to provide a heat fixing roll that is stable over time and has high reliability by forming a coating film using a metal coating method.

[Means for Solving the Problems] The present invention has a heat generating layer on the surface of a support roll whose surface is at least made of a ceramic material, and a ring-shaped electrode electrically connected to both ends of the heat generating layer. In the heating roll provided, a suspension of fine particulate electrode material mixed in an electrically insulating medium is brought into contact with a predetermined position of the ceramic roll, and a ring-shaped electrode pair is inserted into the contact portion, and a high voltage is applied. This heat fixing roll is characterized in that it is constituted by a ring-shaped electrode formed by applying an electric current to a ceramic surface portion between a pair of electrodes and coating an electrode material thereon.

A method of forming a ring-shaped electrode in the heat fixing roll of the present invention will be explained with reference to FIG.

The metal used as the electrode material to be coated (nickel, nickel alloy, copper alloy, etc.) is preferably made into fine particles of 0.5 μm or less. The fine particles are mixed into an electrically insulating medium (white orange oil, transformer oil, etc.) to a volume concentration of about 50% to form a suspension.

The suspension is applied to predetermined positions (two places near both ends) of the heat generating layer of the ceramic roll base material 1 that will become the electrodes by coating or dipping to a thickness of about one shoe. Ring-shaped electrode pairs 44, 44a, and 45.45a having a predetermined shape and clearance are inserted into this contact region.

A voltage higher than DC current [46] is applied to the above electrode (specifically, 2.5 KV when open, about 0.5 KV during continuous discharge) to generate a discharge between the metal fine particles in the coating suspension on the ceramic surface. . At this time, an excessive micro-arc discharge occurs between some of the fine metal particles in the suspension on the ceramic surface, and this arc causes the metal particles and the ceramic surface layer to melt instantaneously. The contact portion between the ceramic layer and the ceramic layer forms a welded layer in which both are mixed. By this method, the ring-shaped electrode pairs 44 and 44a and 45 and 45a
By setting the width of the ring to a desired distance, a ring-shaped power feeding electrode part can be formed.

FIG. 4 also shows an example of the circuit of the power supply device used when using this method, in which 47 is a capacitor, 48.4
9 is a charging resistor and a switch for charging the capacitor 47, respectively, and 50 and 51 are a discharging resistor and a switch for discharging the residual charge of the capacitor 47, respectively.

[Effects of the invention] This method of forming cylindrical electrodes is suitable for forming electrodes on the surface of insulating materials such as ceramics, and the formed metal film has significantly improved adhesive strength and durability. In the heating roll of the present invention, a heat generating layer and a release layer are coated around the support of the ceramic core and formed integrally, and the conductive wires extending from the heat generating layer to both sides are connected to the ceramic core. Connect to ring-shaped electrodes firmly welded to both ends of the

Then, in the bearing housing installed in the frame of the copying machine,
By forming a sliding bearing that also serves as an electrical contact and connecting a conductor from a power source to the sliding bearing, power is supplied to the heat generating layer via the sliding bearing.

Therefore, in the heating roll of the present invention, since power is supplied via a sliding bearing that contacts the surface of the cylindrical electrode,
The area of the contact becomes very large, and it is possible to reliably prevent contact failure and the like from occurring, and furthermore, it is possible to greatly reduce wear on the electrode.

In addition, in the present invention, since the heating roll body is composed of a ceramic core, electrical insulation is achieved in a very good condition, which prevents accidents such as electrical leakage to other members. This eliminates the influence of spark discharge and the like on the control device of the copying machine, and also makes it possible to simplify the configuration of the copying machine.

[Example] The structure of a fixing device using a heat fixing roll of the present invention will be explained with reference to the attached drawings. As shown in FIG. 1 and a pressure roll 10 facing each other.

The heating roll 1 has a cylindrical ceramic core 2 and a
A heat generating layer 3 is coated with a predetermined width, and a release layer 4 is further coated on the surface thereof.

Cylindrical electrodes 5° 5a are provided on both sides of the ceramic core 2, and the cylindrical electrodes and the heat generating layer are connected by conductive wires 6.
, 6a. The cylindrical electrodes 5, 5a are in contact with sliding bearings 7, 7a that support the heating roll 1, and each of the sliding bearings 7.7a is connected to a conductive wire 8 from a power source.
, 8a are connected.

The frames 15 and 158 of the copying machine are each provided with a bearing housing 16.16a formed of an insulating member.
The above-mentioned slide bearings 7, 7a are supported by the bearing housing. The conductive wires 8 and 8a are connected through holes 17 and 178 formed in the bearing housing, and a driving gear 18 is fixed to the outside of the bearing housing 16, and this gear meshes with a motor side gear 19. The heating roll 1 is rotated by rotating the heating roll 1.

As shown in FIGS. 1 and 2, the pressure roll 10 provided opposite the heating roll 1 is formed by covering the surface of a metal core 11 with an elastic body 12, and is supported by a spring or the like. It is brought into contact with the heating roll under a load of approximately ftg, and both sides thereof are supported by bearing members 13 so that it can freely rotate, and rotates in accordance with the rotation of the heating roll 1.

The pressure roll 10 is made of a metal core with a diameter of 15 m, the surface of which is coated with silicone sponge to a thickness of 5 cm, and is brought into contact with the heating roll under a load of 5 kg by a spring or the like.

As shown in FIG.
A paper conveyance path is formed by a guide plate 24 on both sides of the sandwiching portion between the paper 20 and the pressure roll 10, and the toner image @21 formed on the surface of the paper 20 conveyed to the paper conveyance path It is fixed by applying pressure and heating.

Around the heating roll 1, there is a temperature sensor 22 for temperature control, and a peeling claw 2 for peeling off the copy after fixing.
3rd class is provided.

For example, the heating roll 1 has a diameter of 25# and a length of 2.
A ceramic core 2 with a length of 50 m and a wall thickness of 1.5 m is used.
A heat generating layer is formed on its surface, and a fluororesin is roughly coated as a release layer covering the heat generating layer.

The sliding bearings 7 and 7a for supporting the heating roll 1 and supplying power are made of a wear-resistant and conductive member.

An example of this is 100% carbon (manufactured by Opac,
By using the sliding contact GTS-048 (trade name) and connecting it to a 600 watt AC power source through this electrical contact, the temperature up time is approximately 25 seconds, making it a fuser that uses a conventional internal heating element. Compared to , it has become possible to shorten the length considerably.

Next, the structure of an electrophotographic copying machine using a fixing device equipped with a heating roll according to the present invention will be explained with reference to the schematic diagram of FIG.

In the copying machine shown in FIG. 5, charging corotrons 34,
An exposure lamp 35, a light focusing optical system 36, a developing device 37, a transfer corotron 38, a stripping corotron 39, a static eliminator 40, and a cleaning device 41 are provided.

In addition, as a paper conveyance system, a paper feed cassette 27 that stores paper, and a paper feed roll 2 that transports paper 29 from the paper feed cassette 27.
8, and a timing roll 30 for feeding the paper 29 toward the image transfer area in synchronization with the toner image formed on the photosensitive drum 33.

Roughly speaking, a fixing device 26 equipped with the above-described heat fixing roll of the present invention is provided after the image transfer process in order to fix the toner image on the transfer paper, and following the fixing device 26, an ejection tray 31 for storing the copied material is provided. has been established.

In the copying machine having the above configuration, the photosensitive drum 33 is
Before rotating in the direction and irradiating image information, its surface is uniformly charged by a charging corotron 34. Then, the exposure lamp 35 illuminates the image of the document on the document table 32, and the reflected light of the image is illuminated onto the surface of the photoreceptor drum 33 via the light focusing optical system 36 to form an electrostatic latent image. do.

Thereafter, toner is supplied from the developing device 37, and the electrostatic latent image is visualized as a toner image.

The visualized toner image is transferred by the action of the transfer corotron 38 onto a sheet 29 that is fed in time with the image. The paper is then stripped of its charge from the surface of the photoreceptor drum 33 by a stripping corotron 39 and conveyed toward the fixing device 26 .

In the fixing device 26, a sheet of paper is sandwiched between a heating roll 1 and a pressure roll 10 provided opposite to the heating roll, and heat and pressure are applied to melt the toner and apply pressure to the sheet. The final copy is obtained by fixing the toner, and is discharged to the discharge tray 31.

Further, after the image is transferred, residual charges are removed from the toner remaining on the surface of the photoreceptor drum 33 by a static eliminator 40, and then cleaning is performed by a cleaning blade 42 of a cleaning device 41 or the like. Then move on to the next copy cycle.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view in the roll axis direction showing the configuration of a fixing device equipped with the heat-fixing roll of the present invention, FIG. 2 is a side sectional view of the same, and FIG. 3 is the electrode forming force of the heat-fixing roll of the present invention. FIG. 4 is a sectional side view of a conventional heating roll type fixing device, and FIG. 5 is a schematic diagram of an electrophotographic copying machine. Symbols in the figure: 1.1a... Heating roll; 2... Support ceramic roll core; 3... Resistance heating element layer; 4... Release layer; 5,5a... Cylindrical electrode: 6.6a...Conducting wire; 7.7a...Sliding bearing; 8...Conducting wire; 9.
・・Gi V-tub: 10, 10a・・Pressure roll:
11... Metal core: 12... Elastic body; 13,
13a...Bearing: 14.14a...Shaft: 15,
15a... Frame: 16. 16a... Bearing housing: 17, 17a... Hole: 18... Drive gear: 19... Motor side gear: 20... Paper;
21... Toner image; 22... Temperature sensor;
23... Peeling claw; 24... Guide plate; 25...
・Internal heating element: 26...Fixing device; 27...Paper feed cassette: 28...Paper feed roll; 29...Paper; 30...Timing roll; 31...Ejection tray; 32.・・Document stand: 33 ・・Photosensitive drum;
34...Charging corotron; 35...Exposure lamp; 36...Light focusing optical system; 37...Developing device:
38... Transfer corotron; 39... Peeling corotron; 40... Static eliminator; 41... Cleaning device: 42... Cleaning blade; 43.43
a... Electrode forming part: 44, 44a, 45.45a
... Ring-shaped electrode pair: 46 ... DC type source; 47
... Capacitor; 48... Charging resistor; 49...
・Switch: 50...Discharge resistor; 51...Switch. Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] In a heating roll that has a heat generating layer on the surface of a support roll whose surface is made of a ceramic material at least, and a ring-shaped electrode that is electrically connected to both ends of the heat generating layer, a particulate electrode material is electrically heated. A suspension mixed in an insulating medium is applied and brought into contact with a ceramic roll at a predetermined position, a ring-shaped electrode pair is inserted into the applied contact area, and a high voltage is applied to apply the electrode material to the ceramic surface area between the electrode pairs. A heating fixing roll comprising a ring-shaped electrode formed by coating.