JPH0548205Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE PRESENT DISCLOSURE [Industrial Application Field] The present invention relates to a release oil supply roll in a fixing device used in devices such as copying machines, facsimiles, and printers that utilize the electrophotographic process.

[Prior Art] Conventionally, in copying machines and the like that use an electrophotographic process, it is necessary to fix an unfixed toner image formed on paper to make a permanent image. Fixing methods, heat fixing methods, and the like are known.

However, the above-mentioned solvent fixing method has the disadvantage that solvent vapor is scattered, causing many odor and hygiene problems.On the other hand, the pressure fixing method also has poor fixing performance compared to other fixing methods, and is pressure sensitive. The reality is that both toners have the disadvantage of being expensive and are not widely put into practical use.

Therefore, for fixing unfixed toner images, a heat fixing method is generally used in which the toner is melted by heating and adhered to the paper.

There are various heat fixing methods, such as hot air fixing, oven fixing, and heated roll fixing, but the most popular is the heat fixing roll method, in which paper with an unfixed toner image is held between a pressure roll and a heating roll. Common.

The structure of an electrophotographic copying machine using such a heat fixing roll type fixing device will be explained with reference to the schematic diagram of FIG. 4.

In the copying machine shown in FIG. 4, a charging corotron 34, an exposure lamp 35, and a light focusing optical system 3 are arranged around the photoreceptor drum 33 in a predetermined arrangement.
6, a developing device 37, a transfer corotron 38, a peeling corotron 39, a static eliminator 40, and a cleaning device 41 are provided.

The paper transport system also includes a paper feed cassette 44 that accommodates paper, and a paper feed system that feeds the paper 9 from the paper feed cassette 44 toward the image transfer area in synchronization with the toner image formed on the photoreceptor drum 33. Paper roll 45 and timing roll 46
is provided.

Furthermore, a fixing device 43 equipped with a heat fixing roll 1 is provided after the image transfer process to fix the toner image on the transfer paper, and a discharge tray 31 for storing copies is provided following the fixing device 43.

In the copying machine having the above configuration, the photosensitive drum 33
rotates in the direction of arrow A, and its surface is uniformly charged by a charging corotron 34 before being irradiated with image information. 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. After that, toner is supplied from the developing device 37,
The electrostatic latent image is visualized as a toner image.

The visualized toner image is transferred by the action of the transfer corotron 38 to the paper 9 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 stripper 39 and conveyed toward the fixing device 43 .

The fixing device 43 includes a heating roll 1 and a pressure roll 1 provided opposite to the heating roll.
A sheet of paper is sandwiched between the sheet and the sheet of paper, and heat and pressure are applied to melt the toner and fix the toner to the sheet of paper to obtain a final copy, which is discharged onto the discharge tray 31.

Also, after the image is transferred, the photosensitive drum 3
The residual charge is removed from the toner remaining on the surface of the copying machine 3 by the static eliminator 40, and then the cleaning blade 42 of the cleaning device 41 or the like cleans the toner, and the next copy cycle begins.

As shown in FIG. 5, a fixing device conventionally used in such an electrophotographic copying machine has a heater 6 disposed inside a cylindrical core 4 and a polytetra film on the surface of the core 4. Heat-resistant resin such as tetrafluoroethylene, or HTV silicone rubber (High Temperature Vulcanization Silicone)
Rubber), RTV silicone rubber (Room
Temperature Vulcanization Silicone
The fixing roll 1 has a coating layer 5 formed of a heat-resistant elastic material such as
Temperature Vulcanization Silicone
A pressure roll 10 on which a heat-resistant elastic material layer 8 such as RTV silicone rubber, RTV silicone rubber, or fluorocarbon rubber is formed, and a paper 9 on which an unfixed toner image is formed is inserted between these rolls 1 and 10. A heat roll type device for fusing is known, and compared to other heat fusing devices, this has advantages such as low power consumption and less risk of fire due to paper jams in the fusing section. Most widely used.

However, the biggest drawback of this heat roll method is that the toner surface of the paper 9 is directly applied to the fixing roll 1.
Because of the contact with the surface, some of the unfixed toner on the paper 9 is transferred between the fixing rolls 1, and the toner is retransferred to the trailing edge of the paper 9 or to the next paper 9 passing through, staining the paper 9. The so-called toner offset phenomenon occurs.

Therefore, as shown in FIG.
3 and an oil tank 14, etc., is disposed near the fixing roll 1, and a release agent (dimethyl silicone oil, etc.) is continuously applied to the surface of the fixing roll 1 to release the toner. Methods have been adopted to prevent the offset phenomenon.

However, the oil supply device 15 has the disadvantage that it requires a large number of parts such as the wick 11 and the oil pan 12, which makes the fixing device larger and more complicated, and the cost is relatively high. If too much molding agent is supplied or if the molding agent is spilled due to movement of the machine, the paper 9 passing through the fixing device may be stained by the molding agent. Moreover, if the amount of release agent applied is insufficient, the degree of wear on the surface of the fixing roll 1 will increase.
It is necessary to perform cleaning etc. periodically, which has the disadvantage that maintenance and inspection are complicated.

For this reason, in recent years, as shown in FIG. 6, a cylindrical body 16 having a plurality of small holes on its outer peripheral surface and a porous heat-resistant elastic body 17 such as a silicone sponge covering this outer peripheral surface are used. A supply roll 19 in which a liquid mold release agent 18 is sealed inside the cylindrical body 16
is provided in pressure contact with the outer peripheral surface of the fixing roll 1 or the pressure roll 10, and is driven to rotate to apply the release agent 1.
8 has been proposed.

[Problems to be solved by the invention] In this device, the mold release agent 18 is applied to the cylindrical body 16.
Since the mold release agent 18 is sealed inside the mold release agent 18, it has the advantage of not spilling outside and also prevents the fixing device from becoming larger and more complicated. It is difficult to control the amount of coating, and there is a drawback that the amount of coating on the surface of the fixing roll 1 is not constant.

In particular, when the temperature of the fixing roll rises when using the copier first thing in the morning, or when continuous copying is being performed, the temperature of the supply roll rises rapidly, causing the oil sealed inside the roll to rise. The air expands thermally, increasing the internal pressure of the cylindrical body. For this reason, there were disadvantages in that the amount of oil supplied was extremely large and the elastic body covering the cylindrical body was deformed and peeled off.

In order to solve this problem, opening holes may be provided between the rolls to release the internal pressure, but since the oil supply roll rotates together with the fixing roll, there is a drawback that oil leaks from the opening holes. To prevent oil leakage, it is best to place the opening hole as close to the roll rotation axis as possible, and to limit the amount of oil sealed so that the liquid level of the sealed oil is lower than the opening hole. Only 20 to 40% of the volume of the cylindrical body can be filled with oil, and the oil supply roll must be replaced in a short period of time.

Therefore, the purpose of the present invention is to solve the problem of limited oil supply in oil supply rolls that have openings near the rotating shaft to prevent internal pressure rise, and to provide an oil supply roll that can be used for a long time. Our goal is to provide the following.

[Means for solving the problem] As a result of intensive study, the inventors of the present invention passed the conduit of the sealed mold release agent oil tank through an open hole provided near the center of rotation at the end of the cylindrical body, and the tip of the conduit was The above objective was achieved by introducing the mold release agent below the surface of the oil.

That is, the present invention has a plurality of small holes 20 on the outer peripheral surface and an opening hole 21 near the center of rotation at one end, as shown in a side sectional view of one example in FIG. It consists of a cylindrical body 22 that holds oil 18, a porous elastic body 23 that covers the outer circumferential surface of the cylindrical body, and an external sealed mold release agent oil tank 3 having an oil conduit 25. Opening hole 2
1, the oil supply roll for a fixing device is characterized in that the tip thereof is located below the surface of the release agent oil inside the cylindrical body.

In the oil supply roll of the present invention, the tip 26 of the oil conduit extends to near the bottom of the cylindrical body and is normally below the oil surface. If the oil conduit is below the oil level, the oil in the oil tank will not be replenished, but when the oil is consumed and the oil level drops and the oil conduit comes out below the oil level, the oil will become cylindrical. It is designed to be replenished into the body.

[Effect of the invention] Therefore, a certain amount of mold release agent oil in the cylindrical body always exists at the bottom of the cylindrical body.

In conventional oil supply rolls, the supply roll had to be replaced when the oil inside the cylindrical body was consumed, but in the present invention, the supply roll is replenished with oil from the external oil tank 3, so the supply roll This has the advantage that the life of the feed roll can be significantly increased while at the same time the size of the feed roll can be reduced.

In addition, since the inside of the cylindrical body is connected to the atmosphere through the opening hole 21, the pressure inside the cylindrical body is always equal to atmospheric pressure even when the supply roll is heated, so the amount of oil supplied may increase or the oil may squirt out. Also, the elastic body covering the cylindrical body will not peel off.

Note that when using particularly highly viscous oil, when the supply roll begins to rotate, the oil that has accumulated at the bottom tends to adhere to the entire inner surface of the cylindrical body, and the tip of the oil conduit is close to the oil level. It will be more exposed and oil will be replenished more easily. If the rotation of the supply roll is stopped in this state, excessively supplied oil may overflow from the opening hole 21. In order to prevent this, the tip of the oil conduit should be brought as close to the bottom of the cylindrical body as possible so that the tip is not exposed to the oil during rotation, or a valve should be provided in a part of the conduit so that when the supply roll is rotated, All you have to do is try not to replenish the oil.

Note that the supply roll is not limited to one that is disposed on the fixing roll side, but may be one that is disposed on the pressure roll side.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 2 is a side sectional view of the oil supply roll of the present invention (oil tank portion omitted) installed in a fixing device, and FIG. 3 is a partially cutaway perspective view of the supply roll.

That is, the fixing device incorporating the oil supply roll of the present invention is comprised of a fixing roll 1, a pressure roll 10, and a supply roll 2, as shown in FIG.

First, the fixing roll 1 is moved by a power (not shown).
An aluminum cylindrical core 4 with a diameter of 40 mm and a length of 340 mm is rotatably supported in the direction of arrow A at a speed of 150 mm/sec, and the surface of this core 4 is
It consists of a heat-resistant elastic layer 5 of RTV silicone rubber coated with a thickness of 300 μm, and a 1000 W halogen lamp 6 for heating the surface of the fixing roll 1 to 180° C. is disposed within the core metal 4.

On the other hand, the pressure roll 10 is provided below the fixing roll 1, and like the fixing roll 1, the pressure roll 10 has a diameter of
It consists of an iron cylindrical core bar 7 with a length of 30 mm and a length of 340 mm, and a heat-resistant elastic layer 8 of HTV silicone rubber that covers the surface of the core bar 7 with a thickness of 5 mm.
is rotatably supported in the direction of arrow B as the fixing roll 1 rotates, and an appropriate pressure is applied between the fixing roll 1 and the pressure roll 10 by a mechanism not shown. As a result, a nip width of 5 mm is formed between both rolls 1 and 10.

On the paper 9 input side of the fixing roll 1,
A cylindrical supply roll 2 of the present invention, which is in pressure contact with the surface and rotates in the direction of arrow C as the fixing roll 1 rotates, and which has release agent oil sealed inside, is disposed. The release agent is leached from the peripheral wall of the roll 2 and applied to the surface of the fixing roll 1 to prevent the above-mentioned offset phenomenon and the like.

As shown in FIGS. 1 and 3, the supply roll 2 is made of a suitable metal, has a diameter of 20 mm, and has 48 small holes 20 of 3 mm in diameter on its outer peripheral surface.
A cylindrical core bar 22 with a length of 300 mm and a heat-resistant felt with a thickness of 3 mm that covers this core bar 22 (manufactured by Chiyoda Felt Co., Ltd., trade name Nomex, density 0.28) 23
and an oil permeation control layer 24 made of a polytetrafluoroethylene porous sheet (manufactured by Japan Gore-Tex Co., Ltd., trade name Gore-Tex) impregnated with silicone rubber and having a thickness of 0.05 mm and a galley number of 5 seconds, and openings at both ends of the core bar 22. It consists of circular lids 27 and 28 that close the area, and the lid 28 is provided with a through hole 21 having a diameter of 5 mm at a position whose center coincides with the roll rotation axis. Further, an oil conduit 25 from an externally provided sealed oil tank 3 is guided to the inside of the cylindrical body through the center of the opening hole 21 so as not to come into contact with the side wall of the opening hole, and its tip 26 has a cylindrical shape. It exists below the oil level 29 inside the body.

From the nozzle opening hole on the supply roll with the above configuration.
Approximately 50 c.c. of 250 cs silicone oil was injected, and oil with a viscosity of 250 cs was also injected into the external oil tank, both ends of the roll were supported by ball bearings 30, and pressed against the fixing roll with a load of 3 kg. There is.

The toner image is fixed using the fixing device equipped with the supply roll of the present invention, as shown in FIG. The toner was inserted through the fixing roll 1, and the toner was melted by heat transfer from the fixing roll 1, poured into the fibers of the paper 9, and cooled.

At this time, since the release agent oil 18 is supplied from the supply roll 2 to the surface of the fixing roll 1, unfixed toner on the paper 9 does not adhere to the surface of the fixing roll 1, and the above-described toner offset is prevented. We were able to prevent the phenomenon.

Since the supply roll 2 was connected to the atmosphere through the opening holes 21, the pressure inside the supply roll was always equal to the atmospheric pressure and there was almost no change in the amount of oil supplied even under sudden temperature changes.

Furthermore, when we conducted a fusing experiment on 10,000 sheets of A4 size copy paper at a speed of 20 sheets per minute using this fusing device, the oil consumption per sheet was 2 to 3 x 10 ^-6 liters. It was also confirmed that it was almost constant.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of an example of the oil supply roll of the present invention, FIG. 2 is a side sectional view of the oil supply roll of the present invention installed in a fixing device, and FIG. 3 is a side sectional view of an example of the oil supply roll of the present invention. 4 is a schematic diagram showing the configuration of an electrophotographic copying machine using a heat fixing roll type fixing device, and FIG. 5 is a side view of a heat fixing device equipped with a conventional oil supply device. 6 is a side sectional view of an example of a conventional heat fixing device equipped with an oil supply roll. Codes in the figure: 1... Fixing roll, 2... Oil supply roll, 3... Release agent oil tank, 4, 7...
... Core metal, 5, 8 ... Heat-resistant elastic layer, 6 ... Heater, 9 ... Paper, 10 ... Pressure roll, 11 ...
12... Oil pan, 13... Blade, 14... Oil tank, 15... Oil supply device, 16... Cylindrical body, 17... Heat-resistant elastic material layer,
18...Mold release agent oil, 19...Supply roll, 2
0... Small hole, 21... Open hole, 22... Cylindrical body,
23... Heat-resistant elastic body, 24... Oil permeation control layer, 25... Oil conduit, 26... Conduit tip,
27, 28...Lid body, 29...Oil liquid level, 30
... Ball bearing, 31 ... Ejection tray, 3
2... Document table, 33... Photosensitive drum, 34...
Charged 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...Fixing device, 44...
...Paper feed cassette, 45...Paper feed roll, 46...
timing roll.

Claims (1)

[Scope of utility model registration request] A cylindrical body that has a plurality of small holes on its outer circumferential surface and an open hole near the center of rotation at one end thereof and holds a release agent oil therein, a porous elastic body that covers the outer circumferential surface of the cylindrical body, and oil. It consists of an externally installed sealed mold release agent oil tank having a conduit, the oil conduit passing through the opening hole and disposed such that its tip is below the mold release agent oil liquid level inside the cylindrical body. An oil supply roll for a fixing device characterized by: