JPH043323Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a fixing device for a copying machine using an electrophotographic process, and particularly to the structure of an interlocking member for driving a ceramic heating roller.

(Prior Art) Generally, a copying machine using an electrophotographic process is provided with a heated roller type fixing device to fix an unfixed toner image on copy paper. An example of this fixing device is as follows. A heat roller type as shown in FIG. 2 is often used.

In the conventional example shown in FIG. 2, the fixing device 1 is
A heating roller 2 having an internal heating element 3 formed therein and a pressure roller 4 whose surface is coated with an elastic body are provided in parallel, and the paper 5 is passed between the pair of rollers 2 and 4. At this time, the paper 5 is heated and pressurized to fix the unfixed toner image 6 formed on the paper 5.

However, in the conventional heating roller 2, a long halogen lamp is used as a heat source installed inside the heating roller 2, and the heating roller is heated from inside. In many cases, when such an internal heating element 3 is used, it is necessary to heat the entire roller in order to raise the temperature of the surface of the roller 2 to a set temperature. Therefore, the heating roller 2 using the internal heating element 3 as shown in FIG. 2 requires a warming-up time of about 1 to 5 minutes after turning on the switch. The operator has to waste time.

In contrast, recently, in order to shorten the warming-up time, a heating layer is formed on the surface of the heating roller to heat only the surface in a short time without heating the entire roller. Copying machines have been developed that allow the copying operation to begin immediately after the copying machine is turned on.

For example, Japanese Unexamined Patent Publication No. 138766/1983,
Publication No. 172952 and the like discloses a heating roller formed by forming a heat generating layer on the surface of a ceramic core and covering the surface with a release layer. In such a conventional example, since only the surface of the roller is heated by the heating member formed on the surface of the heating roller, the warming-up time can be shortened as described above. .

However, roller members made of ceramic are extremely hard due to their nature, and it is extremely difficult to perform mechanical processing such as polishing and drilling after forming and firing them. Precise molding is required before firing.

However, even after firing, ceramic is not finished in its original shape, and it is unavoidable that some unevenness will be formed. It often becomes necessary to do something. Also,
In the conventional example described above, since the shaft passes through the center of the roller, it is relatively easy to attach the shaft, but the ceramic core is formed into a cylindrical shape. However, for rollers whose ends are directly supported by bearings, it is extremely difficult to machine the notches and holes in the rollers for fixing the drive gear of the drive member. Often.

Furthermore, by firing ceramics,
It is unavoidable that some degree of shrinkage will occur, and that the diameter of the roller of the product will vary by about ±0.3 mm from the designed size. Therefore, in order to fix the drive gear to the ceramic core, the outer diameter of the roller must be polished uniformly and then fitted together. Otherwise, the centers of the roller and drive gear will rub against each other, causing rotation. Unevenness will occur. The above-described machining process causes an increase in the price of the ceramic crawler and, by extension, the price of the fixing device.

(Problems to be solved by the invention) The present invention solves the above-mentioned drawbacks of the conventionally used devices.After firing the ceramic core, the surface etc. of the ceramic core is machined. The purpose of the present invention is to provide a connecting member that allows a drive member to be attached to an object in its original state and driven without any need for a drive member.

(Means and effects for solving the problems) The present invention relates to a heating roller type fixing device in which a heat generating layer is formed on the surface of a cylindrical ceramic core. In the heating roller of the present invention, the heating roller and the driving gear are arranged coaxially, with the small diameter portion provided on the shaft of the driving gear being positioned in the hollow part of the core of the heating roller, and the fitting of both members is performed. A gap is formed between the two members, and a spring member is arranged outside both members, and the inner diameter of the spring member is
The diameter is smaller than the outer diameter of the two members, the heating roller and the gear shaft.

The driving gear combined with the ceramic core is fitted into the hollow part provided in the core with a gap between the small diameter part of the gear without directly contacting the ceramic core body, and both members The outside of the coil spring is connected to the coil spring. When the drive gear is rotated, the coil spring is twisted and its inner diameter is reduced.
The ceramic core is strongly tightened, and the driving force is transmitted through this operation. Therefore, in the device of the present invention, even if the ceramic core has slight manufacturing errors and there is a misalignment of the central axis between it and the drive gear, variations in rotation will occur during the drive. This makes it possible to transmit driving force in a stable state.

(Example) The structure of the fixing device of the present invention will be explained according to the illustrated example. A heat generating layer 15 is formed around the ceramic core 11, and a release layer 16 is coated on the surface thereof. It is supported by bearing members provided on the frame at predetermined positions near both ends thereof, and is rotatable.

One end 12 of the ceramic core 11 of the present invention
A driving gear 20 is disposed therein. This driving gear 20 has a circular cross section, and has a gear 21 at the end.
A large diameter part 22 is formed at the center and a small diameter part 24 is formed at the other end, and a jaw part 23 is provided between the large diameter part 22 and the small diameter part 24. There is. Then, the outer diameter of the large diameter portion 22 with the end member 20 is formed to be the same as the outer diameter of the ceramic core 11,
The end portion 12 of the ceramic core 11 is connected to a driving gear 20.
The small diameter portion 24 is inserted into the space 13 of the roller, and the two are connected by a coil spring 25. Note that the core 1
Since the inner diameter of the space 13 is set larger than the outer diameter of the small diameter portion 24 of the gear member, a gap is formed at the fitting portion of both members.

The inner diameter of the coil spring 25 is formed to be slightly smaller than the outer diameter of both members, so that when connected to both members, the engaging portion of both members is tightened by the coil spring 25, and the coil One end of the spring 25 is fixed to the large-diameter portion 22, and the other end is attached to the ceramic core 11 while being lightly tightened.

In the ceramic heating roller 10 of the present invention, when the gear 21 of the drive gear 20 is rotated by the drive device, the coil spring 25 fixed to the large diameter portion 22 is twisted and its diameter becomes smaller. The surface of the ceramic core 11 is strongly tightened and brought into close contact with the ceramic core 11, so that the rotational torque of the drive gear 20 is completely transmitted to the ceramic core 11.

Therefore, the ceramic heating roller 1 of the present invention
0 has a manufacturing error of approximately ±0.3 mm in the outer diameter of the ceramic core 11, and even if both members, including the drive gear 20, are installed eccentrically, the coil spring 25 is interposed between the two members. Therefore, uneven rotation due to eccentricity is prevented, and the ceramic heating roller 10 can be driven accurately.

Next, embodiments of the present invention will be described.

Example 1 Ceramic core 11 has an outer diameter of 20.0 mm and a wall thickness of 2.5 mm.
mm, length 310 mm, and heat generating layer 15 on the surface.
was formed to have a width of 270 mm, and was coated with fluororesin as a release layer 16.

In this case, the time required to input a current of 100V and 800W to the heat generating layer 15 of the ceramic heating roller 10 and raise the temperature from room temperature to a temperature capable of fixing is 18 seconds, and the time required to raise the temperature from room temperature to a temperature that can be fixed is 18 seconds. The warm-up time is reduced compared to a heating roller using a heating element.

In addition, the ceramic core 11 described above has an outer diameter of 20.0 mm.
A driving gear 20 having a large diameter portion 22 of mm was connected so that the jaw portion 23 lightly contacted the end of the ceramic core 11, and both members were connected by a coil spring 25.

The coil spring 25 used for this connection is a rectangular spring wire with a cross section of 1.3 mm in width and 0.8 mm in height, wound with 10 turns without any gaps, and left in a free state. Using a coil spring with an inner diameter of 19.40 mm,
One end thereof was fixed to the large diameter portion 22, and the other end was fastened to the ceramic core.

Therefore, the ceramic heating roller 1 of the present invention
0, the inner diameter of the coil spring 25 is
Since it is configured to be slightly smaller than the outer diameter of the other members, when it is at rest, it is slightly stretched out and comes into contact with the surfaces of both members.

In the above state, drive gear 20 is rotated at 80mm/sec.
When the coil spring 25 is driven at a speed of
At the same time as the is twisted, the ceramic core 11 and
The large diameter portion 22 of the drive gear 20 is strongly tightened to tightly contact both members.

That is, the ceramic core 11 is connected to the driving gear 20 via the coil spring 25, and the rotational torque of the driving gear 20 is transmitted to the ceramic core 11. At this time, even if a load torque of 10 kg cm is applied to the ceramic core 11, the drive gear 20
And, without slipping with ceramic core 11,
It was definitely rotated.

Example 2 A ceramic core 11 and a driving gear 20 were formed in the same manner as in Example 1, but the outer diameter of the ceramic core 11 was different by ±0.3 mm.

In other words, the outer diameter of the ceramic core 11 is 19.7 mm,
Or, it is formed to 20.3mm, and the inner diameter at rest is 19.5mm.
The connection was made using a coil spring 25.

Even in such a configuration, the drive gear 20
The ceramic core 11 was reliably rotated by this drive, and the drive was carried out in a stable state without any unevenness in rotation due to its eccentricity.

As mentioned above, in the ceramic heating roller of the present invention, by using a coil spring to connect both members, the driving gear can be reliably interlocked with the ceramic core, and the ceramic core can be machined without special machining. , making it possible to transmit driving torque.

Unlike conventional interlocking members, there is no need to machine notches or holes in the ceramic core and fix it, so it is possible to prevent the ceramic from chipping during machining. It turns out.

In addition, in the embodiment of the present invention described above, a case was explained in which a driving gear having a gear formed at the end is interlocked with a ceramic core, but the device of the present invention is not limited to the embodiment as described above. The same effect can be achieved even when a driving sprocket or pulley is used in place of the driving gear. Furthermore, in addition to using a ceramic core as a driven member, it can also be applied to simple ceramic rotating members and members whose connecting parts with drive gears are difficult to machine. It goes without saying that it can be easily used as a rotational torque transmission member even for rotating members with relatively large variations in outer diameter.

(Effects of the invention) Since the ceramic heating roller of the present invention has the above-mentioned configuration, its driving member can be connected very easily, and rotational torque can be generated without special machining. This allows for reliable communication.

In addition, the interlocking member of the present invention allows two rotating members to interlock without performing precise machining, making it possible to reduce the processing cost of each of these constituent members. .

Furthermore, with the ceramic heating roller of the present invention, even if there is a slight shift in the center position when it is installed on a frame, etc., the effect of uneven rotation can be prevented, and vibrations can be caused in the roller device of a copying machine, etc. It is possible to reliably prevent such occurrences.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the configuration of the apparatus of the present invention, and FIG. 2 is an explanatory view of a conventionally used fixing device. Symbols in the diagram: 1...Fuser, 2...Heating roller, 3...Internal heating element, 4...Pressure roller, 5
... Paper, 6 ... Unfixed toner image, 10 ... Ceramic heating roller, 11 ... Ceramic core,
12... end, 13... space, 15... heat generating layer,
16... Release layer, 20... Drive gear, 21...
Gear, 22... Large diameter part, 23... Jaw part, 24...
...Small diameter section, 25...Coil spring.

Claims (1)

[Scope of Claim for Utility Model Registration] In a heating roller type fixing device in which a heat generating layer is formed on the surface of a cylindrical ceramic core, a small diameter portion provided on the shaft of a drive gear is located in a hollow portion of the core of the heating roller. In this state, the heating roller and the driving gear are arranged coaxially, a gap is formed at the fitting portion of both members, and a spring member is arranged outside of both members, and the inner diameter of the spring member is A fixing device characterized in that the fixing device is configured to have a smaller diameter than the outer dimensions of the two members, the heating roller and the gear shaft.