JPH0623908B2 - Liquid-wicking wick for fixing device - Google Patents

Description

Description: FIELD OF THE INVENTION This invention relates generally to electrophotographic copiers, and more specifically, to the separation of toner onto the surface of a fuser member used to permanently affix it to a copy sheet. The present invention relates to a liquid-applying wick for applying a substance.

Problems to be Solved by the Invention A typical electrophotographic copying machine has a photoconductive member, the surface of which is charged to a substantially uniform potential for sensitization.
The charged photoconductive surface is exposed to selectively erase the charge on the surface within the illuminated area. As a result, an electrostatic latent image is recorded on the photoconductive member corresponding to the information in the area contained in the document. After the electrostatic latent image is recorded on the photoconductive surface, the latent image is developed by contact with a developer. Generally, the developer consists of toner particles triboelectrically attached to carrier particles. Toner particles
The carrier particles are attracted to the latent image to form a toner powder image on the photoconductive member. The toner powder image is then transferred from the photoconductive member to a copy sheet. The toner particles are then heated to permanently fix the powder image to the copy sheet.

To fix the toner particles to the copy sheet, it is necessary to raise the temperature of the toner material to the point that its constituents melt and become tacky. By this operation, the toner particles flow to some extent between the fibers of the copy sheet, that is, the pores. Then, when the toner material cools, the toner material solidifies and bonds firmly to the copy sheet.

Heretofore, toner particles are permanently affixed to a copy sheet by the simultaneous application of heat and pressure with a pair of rollers. The rollers are in pressure contact with each other and one roller is heated. Toner particle fusing occurs when a suitable combination of heat and contact pressure is applied. In operation of the fuser, toner particles sometimes set off from the copy sheet to the fuser roll when the copy sheet has an opposing powder image. These particles then transfer to the surface of the backup roll, which is in pressure contact with the fuser roll while there are no copy sheets passing through the nip. When the next copy sheet is fed and passes through the nip, these residual toner particles adhering to the backup roll and fixing roll may adhere to the copy sheet and impair the image quality. One way to solve this problem is to provide an outer layer on the fuser roll made from polytetrafluoroethylene, known under the trade name Teflon under the trade name EIdupout. Oxidize,
That is, various liquid polymer separation materials containing functional groups can be used to prevent settling of the toner particles onto the fuser roll. In this type of device, the separated liquid is
It is applied to the fixing roll by the wick. Suction wicks are commonly used to dispense silicone oil, functional siloxane fluids, mineral oils, and many other separation fluids to the outer surface of a fuser member. As an example, the fuser wick may be a pad placed in contact on a heated fuser roll. Generally, the wick is made up of two different layers, one layer in contact with the surface of the fuser roll to accurately meter the liquid volume thereon. The upper layer, which is in contact with the first layer, has a high separation liquid holding capacity because it supplies the liquid to the first layer. Various wicks have been devised to measure the separated liquid on the surface of the fixing roll. The following patent documents, namely, U.S. Pat. No. 3,745,972 (issued July 17, 1973), No. 4,083,322 (issued April 11, 1978), No. 4,309,957 (issued January 12, 1982),
And No. 4,336,766 (issued June 29, 1982) appear to be related.

The relevant parts of the above patent documents can be briefly summarized as follows.

U.S. Pat. No. 3,745,972 describes a fusing device having a heated fusing roller and a backup roller. The coating roll conveys a thin film of silicon oil from the container dish to the wick. The wick is composed of a Teflon layer in contact with the heated fixing roller and a Nomex layer in contact with the coating roll.

U.S. Pat. No. 4,083,322 discloses a fusing device having a heated fusing roller and a backup roller. The wicking core assembly consists of a Nomex layer, a wool layer, and a porous wiper pad. The wiper pad is in contact with the fuser roll and the Nomex roller is in contact with both the wiper pad and the coating roll. The coating roll rotates in the oil sump. The wool layer is in contact with the surface of the Nomex layer facing the wiper pad. Both the Nomex layer and the wool layer meter the oil to the wiper pad, which applies the oil to the fuser roll.

U.S. Pat. No. 4,309,957 discloses a wick for applying a separating liquid to a fixing roller. The wicking core consists of a fibrous Teflon layer pierced through the Nomex layer. The Teflon layer is in contact with the surface of the fixing roller, and the Nomex layer is in contact with the coating roll placed in the oil sump.

U.S. Pat. No. 4,336,766 discloses a two-layer wicking core consisting of a relatively thick layer and a relatively thin layer. The thick layer feeds the thin layer in contact with the fuser roll. Both layers are made of Nomex.

SUMMARY OF THE INVENTION The present invention provides an apparatus for substantially permanently fixing a toner image to a sheet. The backup roll forms a nip operatively associated with the fuser roll through which the toner image is fused to the sheet as the sheet having the unfused toner image passes therethrough. The suction core measures oil from the oil sump onto the fixing roll. The wick has an oil retaining material in communication with the oil sump. One side of the coating material contacts at least one side of the oil retaining material and the other side contacts the fuser roll to meter the oil thereon. The coating material has at least a first fibrous layer, a second fibrous layer, and a thin, loosely woven material layer sandwiched therebetween. At least a portion of the fibers of the first and second layers are intertwined with the layer of material woven between and in between.

Other features of the present invention will be apparent when referring to the drawings and reading the following description.

EXAMPLES Hereinafter, the present invention will be described with reference to preferred examples, but it will be understood that the present invention is not limited to the examples. Rather, all alternatives, modifications, equivalents, etc. included within the scope and spirit of the invention as claimed are considered to be covered by the invention.

Since electrophotographic printing technology is well known, the following is a brief description of the various processing stations used in copiers and their operation.

A typical electrophotographic copier has a belt having a photoconductive surface deposited on a conductive substrate. The belt advances a continuous portion of the photoconductive surface to various processing stations located around its path of travel. First, a portion of the belt passes through the charging station. At the charging station, a corona generator charges the photoconductive surface of the belt to a relatively high and approximately uniform potential. The charged portion of the photoconductive surface then passes through the imaging station. At the imaging station, the original document is placed on a transparent platen. The lamp flashes the document. The light beam reflected from the original passes through the lens and forms the optical image. The lens images the light image onto the charged portion of the photoconductive surface and selectively dissipates the charge thereon. As a result, an electrostatic latent image is recorded on the photoconductive surface corresponding to the informational areas contained in the original document placed on the platen. The belt then advances the electrostatic latent image recorded on the photoconductive surface to a development station. At the development station, a magnetic brush development system conveys a mixed developer of carrier particles and toner particles to contact the electrostatic latent image recorded on the photoconductive surface. Toner particles are attracted from the carrier particles to the electrostatic latent image to form a toner powder image on the photoconductive surface of the belt. After development, the toner powder image is advanced to the transfer station. At the transfer station, the copy sheet moves and contacts the toner powder image. The corona generator irradiates the back side of the copy sheet with ions,
Aspirate toner powder image to copy sheet. After transcription,
The copy sheet proceeds to the fusing station. At the fusing station, the toner powder image contacts the heated fusing roll as the copy sheet passes between the heated fusing roll and the backup roll. In this way, the toner powder image is permanently fixed to the copy sheet. The detailed structure of the fixing device used in the fixing station will be described later with reference to FIGS. 1 to 3. After exiting the fusing station, the copy sheet advances to the catch tray where the operator removes the completed copy.

For general understanding of the features of the present invention, FIGS. 1-3 are described, wherein like reference numerals are used throughout to refer to like components. FIG. 1 schematically shows the fixing device of the present invention. It will be apparent from the following discussion that the fuser is equally well suited for use in a wide variety of copiers, and its use is not necessarily limited to the particular embodiment described.

Referring to FIG. 1, the fixing device includes a heated fixing roll 10 and a backup roll 12. The temperature sensor 14 is in contact with the outer peripheral surface of the fixing roll 10. The temperature sensor 14 is preferably a thermistor whose resistance changes as a function of the sensed temperature. The fuser roll 10 is made of a hollow tube 16 having a thin cover layer 18. A heat source 20 is arranged inside the tube 16. The tube 16 is made of a metallic material that has the necessary heat transfer properties. As an example, aluminum with a high thermal conductivity,
Copper and other metals are suitable for use as tubes. The cover layer 18 is preferably made of silicone rubber. The heating element 20 is preferably a halogen lamp. The backup roller 12 has a relatively thick silicone rubber layer 22 on a metal tube 24. The backup roller 12 is rotatably mounted on a bracket 26. The bracket 26 is swung by the control device to press the backup roller 12 against the fixing roller 10 and form a nip through which the copy sheet passes. The switch 28 detects the presence / absence of a copy sheet in the fixing device and instructs the control device on the situation. Rollers 10 and 12 are separated from each other whenever a fusing operation is not being performed. When the fixing operation is being performed, the roller 12 turns to press the fixing roller 10. Backup roller 12 and fuser roller 10 are adapted to rotate to feed copy sheets therethrough during the fusing operation. The heat source 20, which should especially be a halogen lamp or an infrared lamp, is located inside the fuser roller 10. The lubrication assembly 32 applies a thin layer of silicone oil to the coating layer 18 of the fixing roller 10 to prevent toner particles from settling to the fixing roller. The lubrication assembly 32 includes a liquid-wicking wick 34, a portion of which is in a sump 36 for wicking silicone oil. The liquid-applied suction core 34 has a coating material 46 in contact with the liquid holding material 48. One side of the coating material is in contact with the fuser roller 10 to meter silicone oil on the roller. It is preferable that the coating material for the liquid-applied wicking core has the characteristics of low friction and resistance to abrasion, has almost no tendency for molten toner to be deposited, and has thermal stability at high temperatures.
The frame 44 holds the liquid holding material 48 and the coating material 46 of the liquid coating suction core 34 at their respective operating positions. The coating material 46 is designed as a compatible component as it is exposed to dirt, buildup and wear. It has been found that the factors limiting the life of the coating material are degradation and wear caused by contact with the rotating fuser roll. As the coating material wears away, fibers escape from the surface and deposit on backup rollers and downstream copy sheets. Finally, wear of this coating material can cause fluff to extend from its surface, sometimes sticking out into the entrance passage of the copy sheet. Prolonging the life of the coating material requires solving the above wear problems.

Next, FIG. 2 shows an enlarged partial sectional view of the liquid-applying suction core 34. The liquid-applied suction core 34 has a coating material 46 in contact with the liquid holding material 48. The covering material 46 is a composite material,
A detailed description will be given later with reference to FIG. As an example,
The liquid holding material 48 is polyester, Teflon,
And can be made from Nomex. Teflon and Nomex are trademarks of E Idupout. Nomex is a highly aromatic amine fiber, such as aramid, a copolymer of metaphenylin diamine and isophaloid chloride. It will be appreciated by those skilled in the art that other suitable materials may be used which hold the required amount of oil inside.

Next, the detailed structure of the coating material 46 will be described with reference to FIG. The coating material 46 consists of three relatively thick layers of fibrous batt 50, 52, 54 and a thin, loosely woven gauze cloth 56, 58 sandwiched between each fibrous batt layer. The cloths 56, 58 are known as scrim cloth. A thin, loosely woven gauze cloth layer 56 is sandwiched between the fiber batt layer 50 and the fiber batt layer 52. Similarly, a gauze-like cloth layer 58 that is roughly woven is sandwiched between the fiber batt layer 52 and the fiber batt layer 54. After the layers have been assembled against each other, the entire coating material is needle punched so that the fibers of the fiber batt layer are entangled in the loosely woven fabric layer sandwiched therebetween. US Pat. No. 3,112,552 (1
Published December 3, 963), a conventional typical needle processing device is disclosed. The needle processing device comprises a plurality of barbed needles adapted to pierce the composite coating material and then withdraw it therefrom. Barbed needles are designed so that the fibers are alternately pulled up and pushed in so that they intertwine with each other. Similarly, the needle process causes the fibers of the fiber batts 52, 54 to become entangled in the loosely woven fabric layer 58 sandwiched therebetween. Fiber batt layer 5
0, 52, 54 include polyester, Teflon (ie polytetrafluoroethylene), Nomex, any suitable synthetic material, or natural fibers such as wool, or any other suitable for metering silicone oils. It can be made from fibers or mixtures thereof. Similarly, scrim cloth sandwiched between the fiber batts 50 and 52, 52 and 54, respectively, ie, the loosely woven gauze cloth layers 56 and 58, are also made of polyester, Teflon (ie, polytetrafluoroethylene). it can be made from natural fibers or any other fibers or mixtures thereof, such as any suitable synthetic fibers or wool, including Nomex. It has been found that the coating materials of the present invention meter a precise amount of silicone oil from the liquid retaining material to the fuser roll while at the same time having significantly improved wear resistance and extended life. A coating material having a fibrous batt layer made of Nomex and a thin, coarsely woven fabric layer sandwiched between them provides a life approximately twice that of a conventional coating material, ie electrophotographic copying. When used in a machine, it is believed to have a life of about 250 million copies.

Effects In summary, the improved coating material consists of multiple fiber batt layers and a thin, loosely woven gauze-like fabric layer sandwiched between each fiber batt layer, which is produced by fiber needle processing of the fiber batt layers. It can be seen that they are entangled in a layer of rough woven fabric sandwiched between them. The coating material produced in this way has better abrasion resistance than the coating materials used hitherto.

From the above description, it is apparent that the present invention provides a liquid-coated wick which completely fulfills the objects and advantages described above. Having described that particular embodiment of the invention, it will be apparent to one of ordinary skill in the art that alternatives, modifications and equivalents are readily envisioned. Accordingly, all alternatives, modifications and equivalents falling within the spirit and broad scope of the claims are considered to be included in the present invention.

[Brief description of drawings]

FIG. 1 is a schematic front view showing a fixing device incorporating the features of the present invention, FIG. 2 is an enlarged partial sectional view showing a liquid-coated suction core used in the fixing device of FIG. FIG. 3 is an enlarged partial sectional view showing the coating material for the coated suction core of FIG. 10 ... Heated fixing roll, 12 ... Backup roll, 14 ... Temperature sensor, 16 ... Hollow tube, 18
...... Thin coating layer, 20 ...... Heat source, 22 ...... Thin layer of silicone rubber, 24 ...... Metal tube, 26 ...... Bracket, 28
...... Switch, 32 ...... Lubrication assembly, 34 ...... Liquid application suction core, 36 ...... Oil sump, 44 ...... Frame, 46 ......
Coating material, 48 ... Liquid holding material, 50, 52, 54 ...
Fiber batt layers, 56, 58 ... Thin, loosely woven material layers.

Continuation of the front page (56) References JP-A-58-111963 (JP, A) Actually opened 59-30158 (JP, U) Actually opened 58-47866 (JP, U) Actually opened 57-175162 (JP , U) US Patent 3745972 (US, A) US Patent 4083322 (US, A) US Patent 4309957 (US, A) US Patent 4336766 (US, A) US Patent 4407219 (US, A)

Claims (9)

[Claims] 1. A fuser roll, a backup roll cooperating with the fuser roll to form a nip in which the toner image is fused to the sheet as the sheet having the unfixed toner image passes therethrough, and an oil sump. A suction core for measuring and applying oil onto the fixing roll, the suction core being in contact with at least one surface of the oil holding material communicating with the oil sump and one surface of the oil holding material. And a coating material whose other surface is in contact with the fixing roll to measure oil, the coating material being at least a first fiber layer, a second fiber layer, the first fiber layer and the A thin, loosely woven material layer sandwiched between second fibrous layers, wherein at least some of the fibers of the first and second fibrous layers are in the rough weave between both layers. A toner image characterized by being entangled with the material layer Apparatus for permanently fixing the over and. 2. The wicking core coating material comprises a third fibrous layer and a second thin, loosely woven material layer sandwiched between the second and third fibrous layers. And has the second
A fiber layer and at least a part of fiber of a 3rd fiber layer are intertwined with the said 2nd rough woven material layer pinched | interposed between both layers, Claim 1 characterized by the above-mentioned. apparatus. 3. A first fibrous layer of coating material for the wicking core,
A device according to claim 2 comprising fibers selected from the group of polyester, polytetrafluoroethylene, aramid, and wool fibers. 4. The second fiber layer of the coating material for the wicking core comprises polyester, polytetrafluoroethylene, aramid,
A device according to claim 2, characterized in that it contains fibers selected from the group of wool fibers. 5. The third fiber layer of the wicking core coating material comprises polyester, polytetrafluoroethylene, aramid,
A device according to claim 2, characterized in that it contains fibers selected from the group of wool fibers. 6. The first rough weave material layer of the wicking core coating material is polyester, polytetrafluoroethylene,
A device according to claim 2, characterized in that it comprises fibers selected from the group of fibers of aramid and wool. 7. The second rough weave material layer of the wicking core coating material is polyester, polytetrafluoroethylene,
A device according to claim 2, characterized in that it comprises fibers selected from the group of fibers of aramid and wool. 8. The fibers of at least a part of the first fiber layer and the second fiber layer of the coating material for the wicking core are entangled with the first rough weave material layer by needle processing. The apparatus according to claim 2, wherein 9. The wicking core coating material at least part of the fibers of the second fiber layer and the third fiber layer are entangled with the second rough weave material layer by needle processing. The device according to claim 2.