JPH0744047A - Fixing device - Google Patents

Abstract

PURPOSE:To stably perform power supply to a heating roller provided with an exothermic resistor layer. CONSTITUTION:As to the heating roller 15 in which the exothermic resistor layer 18 is provided on the external periphery of a cylindrical core bar 16 through an insulating layer 17, energizing members 23 are attached to both ends of the core bar 16 through insulating sleeves 22; the exothermic resistor layers 18 are connected to the energizing members 23 through screws 24 and electrodes 26; brushes 31 for the power supply connected to a power source 32 are pressed against the end faces of the energizing members 23 being sliding surfaces 23b for the power supply, so that the heating roller is conducted. By this constitution, relative sliding speed between the sliding surface 23b and the brush 31 becomes small, so that stable power supply can be performed.

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 electrophotographic recording device used in a plain paper facsimile machine, a copying machine or the like.

[0002]

2. Description of the Related Art Heat roll fixing has been a fixing method that has been suitable for low cost and downsizing. As shown in FIGS. 7 and 8, the fixing device for performing the heat roll fixing includes a heating roller 1 and a backup roller 2 that is in pressure contact with the heating roller 1. The heating roller 1 has a roller body 3 having a release layer such as a Teflon film on its surface, and a halogen lamp 4 penetrating the inside of the roller body 3. The heating roller 1 emits heat from the halogen lamp 4 and conducts heat. The roller body 3 is configured to be heated via the air layer. On the other hand, backup roller 2
Has a coating of silicone rubber or the like on its surface. The sheet 5 on which the toner image is to be fixed is conveyed while being pressed against the heating roller 1 by the backup roller 2, and during that time, the toner image is heated and fixed on the sheet by the heat of the heating roller 1.

However, since the conventional heating roller using the halogen lamp is heated by radiation, there is a problem that the heat transfer performance is poor, the temperature rise takes a long time, and the thermal efficiency is poor. Further, there is a limit to reducing the diameter of the heating roller 1 (for example, the diameter is about 20 mm), and thus there is a limit to downsizing the entire fixing device.

In order to solve this drawback, as shown in FIG. 9, an insulating layer 9, a resistor layer 10 and a Teflon layer 11 are provided on the outer peripheral surface of a roll body 8 made of a metal pipe, and both ends of the resistor layer 10 are provided. There is proposed a heating roller 7 having a structure in which electrodes 12a and 12b are provided in a ring shape respectively, and a current is applied from the electrodes 12a and 12b to the resistor layer 10 to heat the resistor layer 10 (see, for example, JP-A-59-67567).

[0005]

However, in the heating roller 7 having the structure shown in FIG. 9, annular electrodes 12a and 12b are provided at both ends of the heating roller 7 in order to energize the resistor layer 10, and the electrodes are provided with a brush for power supply. Although not shown, the relative sliding speed of the brush and the electrode during rotation of the heating roller 7 is high, which causes jumping of the brush to easily cause contact failure. There was a problem that the wear of the electrodes was great.

The present invention has been made in view of the above-mentioned problems, and in a heating roller using a resistor for heat generation, the sliding surface provided on the heating roller side for energizing the resistor is externally connected. It is an object of the present invention to provide a fixing device including a heating roller capable of stably contacting the power supply member and reducing the amount of wear.

[0007]

In order to solve the above-mentioned problems, the invention of claim 1 of the present application is such that an insulating layer, a heating resistor layer, and a mold release are formed on the surface of a cylindrical core metal forming a heating roller. Layers are provided in this order, and in order to energize the heating resistor layer, power feeding members having end faces as sliding surfaces for power feeding are attached in an insulating relationship to the core bar at both ends of the core bar. It is provided with a structure in which conductive means is provided for connecting both ends of the resistor layer to the power supply members in the vicinity thereof.

According to a second aspect of the present invention, in the heating roller having the above structure, an insulating layer is further interposed between the heating resistor layer and the release layer.

According to a third aspect of the present invention, a cylindrical core metal forming the heating roller is used as a first electrode, and a heating resistor layer, a second electrode layer, and a release layer are provided on the surface of the first electrode in this order. In order to energize the heating resistor layer, a first power feeding member having an end face as a sliding face for power feeding is provided in a conductive relationship at one end of the core metal, and an end face is provided at the other end of the core metal for power feeding. The second power feeding member, which is a moving surface, is attached to the core metal in an insulating relationship, and further,
It is provided with a structure in which a conducting means for connecting the second electrode layer to the second power feeding member is provided. Even in this case, an insulating layer may be further interposed between the second electrode layer and the release layer.

[0010]

According to the invention of claim 1, the power feeding brushes connected to the power source are pressed against the power feeding members at both ends of the heating roller to feed power, thereby causing a current to flow through the heating resistor layer in the longitudinal direction to generate heat. Therefore, the surface of the heating roller can be heated to a predetermined temperature necessary for fixing. Here, since the end faces of the power feeding members at both ends of the heating roller are sliding faces for power feeding, and the sliding faces are located in the vicinity of the center of rotation of the heating roller, relative to the brush for power feeding. The sliding speed is extremely low, so that the contact state is stable, reliable energization is possible, and wear can be reduced.

According to the second aspect of the present invention, the insulating layer is arranged between the heat-generating resistor layer below the release layer forming the roller surface, so that the insulation with respect to the release layer surface becomes more reliable.
High safety.

According to the third aspect of the present invention, the power feeding brushes connected to the power source are pressed against the power feeding members at both ends of the heating roller to feed power, so that between the core metal as the first electrode and the second electrode layer. A current can be passed through the heating resistor layer in the direction of thickness to generate heat, and the surface of the heating roller can be heated to a predetermined temperature necessary for fixing. Also in this case,
Since the power feeding sliding surfaces are formed on the end surface portions of both ends of the heating roller and are located near the center of rotation, the relative sliding speed with the power feeding brush is extremely low, and therefore the contact state is maintained. Stable and reliable energization is possible, and wear can be reduced.

[0013]

FIG. 1 is a schematic sectional view showing a heating roller used in a fixing device according to an embodiment of the present invention and means for energizing the heating roller, FIG. 2 is a schematic exploded perspective view of a main portion thereof, and FIG. 3 is a drawing of the heating roller. It is a schematic sectional drawing. 1 to 3, a heating roller indicated by reference numeral 15 as a whole has a cylindrical core metal 16 formed of a metal material such as aluminum, and an insulating layer 17 is formed on the outer peripheral surface of the core metal 16. The heating resistor layer 18, the insulating layer 19, and the release layer 20 are formed in this order. The release layer 20 constitutes the roller surface that contacts the paper to be fixed, and is selected to be larger than the maximum paper width to be handled. As the release layer 20, a release material such as Teflon is used so that the toner does not adhere thereto.
The thickness of the release layer 20 is preferably thin in order to improve the heat transfer from the heating resistor layer 18, and is usually 20 μm or less.

The insulating layer 19 surely insulates the surface of the release layer 20 from the heating resistor layer 18, and is formed to have a width equal to or wider than that of the release layer 20. Since the release layer 20 usually has an insulating property in many cases, the insulating layer 19 may be omitted in some cases. However, for safety and manufacturing reasons, it is most preferable to provide the insulating layer 19 between the release layer 20 and the heating resistor layer 18. For one, the release layer 20 has a thickness of only 20 μm, and if there is a pinhole or abrasion, current will leak from the heating resistor layer 18, which will affect the heat generation characteristics and is not preferable for safety.

Further, conductive powder is mixed in the heating resistor layer 18, and depending on the shape of the powder, the smoothness of the surface is impaired, and variations in the pressing force against the paper surface and toner adhesion can be fixed. There is a nature. As a material of the insulating layer 19,
Insulating resins, ceramics, etc. can be mentioned. Also, the thickness of the insulating layer 19 is preferably thin so that heat transfer to the release layer 20 is good, and is preferably 20 μm or less.

The heating resistor layer 18 is composed of a resistor that generates heat when energized, and various conductive ceramics and conductive resins can be used. This heating resistor layer 18
The resistance value of the resistor composing the
00V) is used to secure a desired calorific value (a calorific value capable of raising the roller surface to 150 to 180 ° C.) when a current is passed in the longitudinal direction of the heating roller, Usually, it is preferable that a 10 ⁰ ~10 ¹ Ω · cm. The heating resistor layer 18 is the insulating layer 1 formed thereon.
It is formed in a width wider than 9 and allows electrodes for energization to be attached to the outer peripheral surfaces of both ends.

The insulating layer 17 includes a cored bar 16 and a heating resistor layer 18
For insulation from the heating resistor layer 18
The width is wider than that. The material of this insulating layer 17 is similar to that of the insulating layer 19. This insulating layer 17 is preferably made thick so that the heat of the heating resistor layer 18 is less likely to be transferred to the core metal 16, and is usually preferably 50 μm or more.

These insulating layer 17, heating resistor layer 18,
The following combinations can be given as specific examples of the release layer 19 and the release layer 20.

[0019]

[Table 1]

The diameter of the cored bar 16 is determined so that the outer diameter of the heating roller 15 (outer diameter of the release layer 20) has a desired value, and usually the overall size is reduced and the heat radiation and heat capacity are reduced. It is preferable to select a small diameter (for example, 10 to 15 mm) in order to reduce the temperature and improve the thermal efficiency and temperature rising characteristics. When the diameter of the portion of the core metal 16 where the release layer 20 is provided is selected to be small, as shown in the drawing, the core metal 1
6 has the same diameter over the entire length, but when the release layer 20 has a large diameter (for example, about 25 mm), the portion supported by bearings (not shown) at both ends of the cored bar 16 has a small diameter. May be

The flanges 2 are provided on both ends of the cored bar 16, respectively.
An insulating bush 22 having 2a is fitted therein, and a power feeding member 23 made of a metal material is inserted into the insulating bush 22. A flange 23a that abuts the insulating bush 22 is formed at the outer end of the power feeding member 23, and the end surface thereof is a power feeding sliding surface 23b.
Further, a screw hole 23c is formed in the vicinity of the end of the power feeding member 23 on the side opposite to the sliding surface 23b. On the other hand, core metal 16
Further, the insulating layer 17 on the surface thereof has a hole 25 through which the screw 24 penetrates, at a position facing the screw hole 23c of the power feeding member 23 attached at a predetermined position with respect to the core metal 16. An electrode 26 is attached to the outer peripheral surface of the end portion of the heating resistor layer 18 by a pressing spring 27.
Is provided with a projecting piece 26a having a hole 26b formed at a position overlapping the hole 25. The screw 24 is made of a conductive material. Thus, the screw 24 is passed through the hole 26b of the electrode 26, the insulating layer 17 and the hole 25 of the cored bar 16 and is screwed into the screw hole 23c of the power supply member 23 located thereunder, whereby the insulating bush 22 and the power supply member 23 are inserted into the cored bar. 16 and the heating resistor layer 18 can be electrically connected to the power feeding member 23. Therefore, screw 2
4. The electrode 26 constitutes a conducting means for connecting the heating resistor layer to the power feeding member.

Power supply brushes 31 attached to the leaf springs 30 are provided at both ends of the mounting position of the heating roller 15.
The power supply brush 31 is pressed against the sliding surface 23 b of the power supply member 23 by the spring force of the leaf spring 30. Further, a power supply (usually an AC power supply) 32 is connected to the leaf springs 30 on both sides. These constitute means for energizing the heating roller 15.

Although not shown in FIG. 1, a backup roller is provided so as to be in pressure contact with the heating roller 15 to form a fixing device.

In the fixing device provided with the heating roller 15 having the above-mentioned structure, the sliding surface 23 between the power feeding brush 31 and the power feeding member 23 is provided.
The power source 32 is connected to both ends of the heating resistor layer 18 by contact with b, and a current flows in the heating resistor layer 18 in its longitudinal direction to generate heat. As a result, the surface of the release layer 20 is heated to a desired temperature, and the paper passing between the release roller 20 and the backup roller can be fixed. FIG. 4 shows characteristics of the electric power temperature rising time until the desired fixing temperature (150 degrees) is reached for the conventional halogen lamp and the heating roller 15 of the present application.
Shown in.

According to this embodiment, the following advantages can be obtained. (1) Since the end faces of the power feeding member 23 at both ends of the heating roller 15 are the power feeding sliding faces 23b, the sliding faces 23b are located in the vicinity of the center of rotation of the heating roller. Even if the peripheral speed is high, the moving speed of the sliding surface 23b is extremely low, and therefore the relative sliding speed with the power supply brush 31 is extremely low. For this reason, the contact state is stable, reliable energization is possible, and the occurrence of wear is small. (2) Since the heat source is located on the outer circumference of the heating roller, there is no need to raise the heat generation temperature as compared with the case of using a conventional halogen lamp, which is safe. (3) As is clear from the experimental result of FIG. 4, the insulating layer 1
Since 7 is thickened to prevent heat conduction to the cored bar 16, the heat capacity is small and the overall diameter is also small. From this point as well, the heat capacity is small and the heat-up time is extremely short. In general, when used for LBP FAX, there is an interval of several tens of seconds from the incoming call to the recording, but when viewed at a practical power of 500 W, the heating roller 15 has 20 seconds.
Since it takes less than a second to start up, it is not necessary to heat up the fixing unit during standby as in the past, and it is sufficient to heat up after receiving a call, so heating of the heating roller is turned off during normal standby The power consumption is low and the safety is high. (4) By reducing the outer diameter of the heating roller, the entire fixing device can be downsized. (5) The heating efficiency is good and the power consumption can be reduced as compared with the conventional halogen lamp.

FIG. 5 is a schematic sectional view showing a second embodiment of the present invention, and FIG. 6 is a schematic sectional view thereof. The same parts as those of the embodiments of FIGS. 1 to 3 are designated by the same reference numerals. There is. A heating roller indicated by reference numeral 35 in its entirety is formed of a metal material such as aluminum and has a cylindrical core metal 36 also serving as a first electrode,
A heating resistor layer 37, a second electrode layer 38 formed of a metal layer, an insulating layer 19, and a release layer 20 are formed in this order on the outer peripheral surface of the cored bar 36. The release layer 20 and the insulating layer 19 used here are also the same as the release layer 20 and the insulating layer 19 of the embodiment of FIG.

The heating resistor layer 37 generates heat when energized, but in this embodiment, a current is made to flow in its thickness direction, and therefore its resistance value is that when a current is made to flow in the thickness direction. Is selected so that the desired heat generation can be obtained. As the material, as in the embodiment of FIG. 1, conductive ceramic, conductive resin, or the like is used.

A first power feeding member 40 is attached to one end of the cored bar 36 so as to establish a conductive relationship with the cored bar 36. The power feeding member 40 has an outer end surface as a power feeding sliding surface 40a. On the other hand, the insulating sleeve 22 is fitted to the opposite end of the cored bar 36, and the second power feeding member 23 is inserted therein. On the outer end surface of the second power supply member 23, a power supply sliding surface 23b is formed.
In addition, a means for connecting the power feeding member 23 to the second electrode layer 38 is provided. This means also has the same configuration as that of the embodiment of FIG. 1, and the electrode 26 attached to the outer periphery of the second electrode layer 38 by the pressing spring 27 and the projecting piece 26a provided on the electrode 26 are provided as the power feeding member. It has a screw 24 for conducting to 23 and fixing the power feeding member 23. An insulating layer 42 for insulating the second electrode layer 38 and the protrusion 26a of the electrode 26 from the cored bar 36 is provided below the second electrode layer 38 where the electrode 26 is attached. .

At both ends of the mounting position of the heating roller 35, as in the embodiment of FIG. 1, a power feeding brush 31 mounted on the leaf spring 30 is provided, and the power feeding brush 31 is fed by the spring force of the leaf spring 30. Sliding surfaces 23b, 4 of the members 23, 40
It is pressed against 0a. Further, a power source 32 is connected to the leaf springs 30 on both sides. These constitute means for energizing the heating roller 35.

Also in the embodiment shown in FIGS. 4 and 5, the power feeding members 23 and 40 at both ends of the cored bar 36 are connected to the power source 32 by the power feeding brushes 31. As a result, the core metal (first electrode) 36 and the second electrode layer 38 located inside and outside the heating resistor layer 37 are connected to the power source 32, and a current flows through the heating resistor layer 3
7 flows in the thickness direction to generate heat. As a result, the surface of the release layer 20 is heated to a desired temperature, and the paper passing between the backup roller (not shown) can be fixed. Also in this embodiment, the same effect as that of the embodiment shown in FIGS. 1 to 3 can be obtained.

[0031]

As is apparent from the above description, according to the first aspect of the present invention, the insulating layer, the heating resistor layer, and the release layer are provided on the surface of the cylindrical core metal forming the heating roller. In order to energize the heating resistor layers, the power feeding members having the sliding surfaces for power feeding are attached to both ends of the core bar in an insulating relationship with the core bar. Since there is provided a configuration in which conductive means for connecting both ends of each of the power supply members in the vicinity thereof are provided, by supplying power to the power supply members at both ends through the power supply brush,
An electric current is passed through the heating resistor layer in the longitudinal direction to generate heat, and the surface of the heating roller can be heated to a predetermined temperature required for fixing. By locating it in the vicinity of, it is possible to reduce the relative sliding speed with the power supply brush, which stabilizes the contact state and enables reliable energization.
It has the effect of reducing wear.

Further, according to the second aspect of the present invention, the insulating layer is arranged between the heat release resistor layer below the release layer forming the roller surface, so that the insulation with respect to the release layer surface becomes more reliable. It has the effect of high safety.

Further, in the invention according to claim 3, the cylindrical core metal forming the heating roller is used as the first electrode, and the heating resistor layer, the second electrode layer, and the release layer are formed on the surface thereof. In order to energize the heating resistor layers provided in this order, a first power feeding member having an end surface as a power feeding sliding surface is provided in a conductive relationship at one end of the core metal, and an end surface is provided at the other end of the core metal. A second power feeding member having a sliding surface for power feeding is attached to the core metal in an insulating relationship, and further, a conductive means for connecting the second electrode layer to the second power feeding member is provided. Therefore, by feeding power to the power feeding members at both ends of the heating roller via the power feeding brush, a current is caused to flow in the thickness direction in the heating resistor layer between the cored bar which is the first electrode and the second electrode layer. To heat the surface of the heating roller to a predetermined temperature required for fixing. At this time, by locating the sliding surface for the power feeding brush in the vicinity of the center of rotation of the heating roller, the relative sliding speed with the power feeding brush can be reduced, and therefore the contact state is stable and reliable. It has an effect that it can be energized for a long time and can reduce wear.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a heating roller used in a fixing device according to an embodiment of the present invention and means for energizing the heating roller.

FIG. 2 is an exploded perspective view of a main part of a heating roller of the present invention.

FIG. 3 is a schematic sectional view of a heating roller of the present invention.

FIG. 4 is a diagram showing temperature rising characteristics of the heating roller of the present invention.

FIG. 5 is a schematic cross-sectional view showing a heating roller used in a fixing device according to a second embodiment of the present invention and means for energizing the heating roller.

FIG. 6 is a schematic sectional view of a heating roller according to a second embodiment of the present invention.

FIG. 7 is a schematic front view showing a roller constituting a conventional fixing device with a part thereof cut away.

FIG. 8 is a schematic cross-sectional view showing a state where a sheet passes through a conventional fixing device.

FIG. 9 is a schematic cross-sectional view showing a heating roller having another configuration used in a conventional fixing device.

[Explanation of symbols]

 15 Heating Roller 16 Core Bar 17 Insulating Layer 18 Heating Resistor Layer 19 Insulating Layer 20 Release Layer 22 Insulating Sleeve 23 Power Supply Member 23b Power Supply Sliding Surface 24 Screw 26 Electrode 27 Presser Spring 35 Heating Roller 36 Core Bar (First Electrode) ) 37 heating resistor layer 38 second electrode layer 40 power feeding member 40a power feeding sliding surface

Claims (3)

[Claims] 1. A heating roller and a backup roller in pressure contact with the heating roller. The heating roller comprises a cylindrical core metal, an insulating layer provided on the surface of the core metal, and a surface of the insulating layer. A heat generating resistor layer provided, a release layer formed on the surface of the heat generating resistor layer, and a power feeding member that is attached to both ends of the core metal in an insulating relationship with the core metal and forms a power feeding sliding surface on the end face. And a conducting means for connecting both ends of the heating resistor layer to power supply members in the vicinity thereof, respectively. 2. The fixing device according to claim 1, further comprising an insulating layer between the heating resistor layer and the release layer. 3. A heating roller and a backup roller in pressure contact with the heating roller, wherein the heating roller has a cylindrical core metal that also functions as a first electrode, and a heating resistor layer provided on the surface of the core metal. A second electrode layer provided thereon, a release layer provided on the surface thereof, and one end of the cored bar provided in conductive relation with the cored bar, the end surface of which is a sliding surface for power feeding. One power feeding member, a second power feeding member that is attached to the other end of the cored bar in an insulating relationship with the cored bar, and forms a power feeding sliding surface on the end face, and the second electrode layer. A fixing device comprising: a conducting means connected to the second power supply member.