DE60111007T2 - A fixing roller assembly of a heating coil electrophotographic image forming apparatus around a heat transfer roller - Google Patents

Description

The The present invention relates to a fuser roll assembly for one electrophotographic image forming apparatus, and, in particular, on a fixing roller assembly for an electrophotographic image forming apparatus instantaneously can be heated with a low energy consumption.

In a general electrophotographic image forming apparatus, such as a copying machine and a laser beam printer, when an electrostatic roller is placed adjacent to a photoreceptor drum, rotates, a photosensitive material coated on the surface of the PR drum, uniform charged. The charged photosensitive material becomes a Laser beam exposed by a laser scanning unit (LSU) scanned so that a latent, electrostatic image in a predetermined Pattern is formed on the photosensitive material. A developer unit performs toner to the photosensitive material to the latent, electrostatic Image, made on the photosensitive material, into a visible one Develop toner image. A predetermined transfer voltage is applied to a transfer roller applied in contact with the photoreceptor drum under a predetermined force is brought while the photoreceptor drum carries the toner image. In this state, when a printing paper enters the gap between the transfer roller and the photoreceptor medium, the toner image on the photosensitive material, applied to the printing paper. A fuser comprising a fuser roll heats instantly the printing paper to which the toner image is transferred to the toner image melt on the printing paper and fix it. Generally For example, a halogen lamp is used as a heat source for the fixing unit. The halogen lamp is installed inside the melting roll and heated the surface the melting roll to a target temperature with radiant heat.

In a conventional one Fuser roll arrangement of an electrophotographic Image forming device using a halogen lamp as a heat source used, the outer surface of the Melting roll heat produce; the melting roll is therefore from the inside by radiation heat heated by the halogen lamp. A pressure roller is arranged below the melting roll. One Paper carrying a toner image in a powder form passes between the fuser roll and the pressure roller, the paper is at a predetermined Force pressed and the toner image is passed through on the printing paper the heat and the force of the melting roll and the pressure roller melted and fixed.

One Thermistor can detect and convert the surface temperature the melting roll are used in an electrical signal and a thermostat can be used to supply the power to interrupt the halogen lamp.

A conventional Melting roller assembly comprising a halogen lamp as a heat source uses, consumes unnecessarily a big Amount of energy, and needed a considerable one long warm-up period, though the image forming apparatus for an image generation is turned on. In other words, after applying the energy, a standby period until the temperature the melting roll a set temperature, for example, for some ten seconds to a few minutes, reached. It has been found that with a conventional Melting roll arrangement, due to the fact that the melting roll by radiant heat of the heat source heated is the rate of heat transfer is low. In particular, a compensation of temperature variations due to a drop in the temperature of the heating roller, caused by a contact with a printing paper, delayed, making it difficult is, uniform the distribution of temperature along the axial length of the Check the melting roll. Especially in a standby mode, where The operation of the printer is exposed to energy needs periodically supplied to keep the temperature of the melting roll constant, making an unnecessary Energy consumption needed becomes. Also needed it a considerable one Period of time to the fuser roll from their standby mode to a Operating mode for to switch an image output so that the resulting image is not can be printed quickly.

One alternative construction for a conventional one Aufschmelzrollenanordnung sets a hot plate, arranged in a lower portion of a flexible cylindrical film tube, wherein a pressure roller is mounted below the heating plate. The film tube is rotated by a separate turntable and becomes local a part between the heating plate and pressure roller heated and deformed. While this method of locally heating the film tube with a Hotplate has been considered to be advantageous in terms of On a low energy consumption, it is not for a high speed printing suitable.

Japanese Patent Application No. Sho 58-163836 (September 16, 1983); Hei 3-107438 (May 13, 1991); Hei 3-136478 (June 7, 1991), Hei 5-135656 (June 7, 1993); Hei 6-296633 (November 30, 1994); Hei 6-316435 (December 20, 1994); Hei 7-65878 (March 24, 1995); Hei 7-105780 (April 28, 1995); Hei 7-244029 (22 September 1995); Hei 8-110712 (May 1, 1996); Hei 10-27202 (February 9, 1998); Hei 10-84137 (March 30, 1998); and Hei 10-208635 (July 8, 1998) disclose a heat pipe-equipped fuser roll assembly.

A such reflow roller assembly using heat pipes can instantly to be heated whereby energy consumption is reduced. The melting roll arrangement also has a short delay period, when switching between a standby and a print mode becomes. In particular, the fuser roll assemblies set in Japanese Patent Application Nos. Hei 5-135656; Hei 10-84137; Hei 6-296633 and Hei 10-208635, different types of heat sources are disclosed at one end of the fuser rolls positioned over the fuser areas are. The arrangement of the heat source for every these reflow roller assemblies increase the volume of the reflow roller assembly and requires complex structures. As a result, there is a requirement present, the structural complexity of such fuser roll assemblies to improve.

The Fuser roll assemblies disclosed in Japanese Patent Applications No. Sho 58-163836; Hei 3-107438; Hei 3-136478; Hei 6-316435; Hei 7-65878; Hei 7-105780; and Hei 7-244029 are disclosed possess their heat sources arranged within their melting rollers, so there is a problem remains elevated Assign volume of these devices, which are described above is. A plurality of local heat pipes is however for each melting roll installed, eliminating the manufacturing and manufacturing the Aufschmelzrollenanordnung is complicated. The local arrangement the heat pipes causes tempera ture deviations between the contact areas of the heat pipe and the non-contact areas of the heat pipe.

The EP 0 399 376 discloses a heat fixing roller for a copying machine, wherein an insulating layer and a resistance layer are formed on the surface of a hollow metal pipe so that when a current passes through the resistance layer, the outer surface of the fixing roller is heated.

The JP 0 919 7863 discloses a sealed heat pipe which is heated by an external coil winding, the sealed heat pipe containing a heat transfer fluid. This document forms the preamble of the claims appended hereto.

It An object of the present invention is an electrophotographic Image forming apparatus and a method to create that to address these and other problems in the art.

A preferred object is to provide a Aufschmelzrollenanordnung for an electrophotographic Imaging device to provide, in which a local temperature deviation a melting roll is greatly reduced, thereby reducing the total, to improve thermal distribution characteristics.

A Another preferred object of the present invention is to provide a Melting roller arrangement for to provide an electrophotographic image forming apparatus which is easy to manufacture and is designed to be any Magnification of the Size of the melting roll arrangement to minimize.

A another, preferred object is to provide a melting roll, which is capable of from their standby state to their printing state in a shorter time Time period to pass.

A Another, preferred task is a more energy efficient, electrophotolithographic To provide method and a corresponding device.

A Another, preferred task is a fuser roll, a process for building up a melting roll and a method for melting electrostatic images, formed of toner, on a printable Medium, to create, with an arrangement that is capable of Temperature of the melting roll from room temperature to an operating temperature within a shorter time Time period to change.

A Another, preferred task is a fuser roll, a process for building up a melting roll and a method for melting of electrostatic images, formed from toner, on a printable Medium, to create, with an arrangement that is able to enable, that the temperature of the melting roll at room temperature during a Standby operating period remains.

A Another, preferred task is a fuser roll, a process for building up a melting roll and a method for melting of electrostatic images, formed from toner, on a printable Medium, to create, with an arrangement that is an improved, thermal equilibrium and minimal, local, thermal differences on the cylindrical outer surfaces of the Melting roller shows.

According to one The first aspect of the present invention is a fuser roll assembly The invention relates to a cylindrical melting roll comprising provides an axially oriented cavity; a heat pipe, the opposite Having sealed ends, forming an evacuated chamber under the a vacuum is maintained, coaxially positioned within the Aufschmelzrolle; and an electrically conductive coil spirally around a cylindrical outer surface of the heat pipe wrapped around, coaxially interposed between the cylindrical Outside surface of the heat pipe and an inner cylindrical surface of the cavity and these touching.

Prefers will, before the introduction the coil into the cavity, the coil has an outside diameter larger than have the inner diameter of the Aufschmelzrolle, so that at least some turns of the coil an inner, cylindrical wall of the cavity touch with a force.

Prefers is the heat pipe made of copper. Preferably, the fuser roll is formed of aluminum.

Prefers For example, the fuser roll assembly has a working fluid that is within the chamber is included. Suitably, the working fluid is distilled Water. Preferably, an amount of the working fluid is contained within the chamber, in the range of 5-50 vol .-% of the chamber. Ideally is the amount of working fluid contained within the chamber, in the range of 5-15 Vol .-% of the chamber.

Prefers adjacent turns of the coil are axially spaced apart; and a spacer made of a thermally conductive material interposed between the adjacent turns of the coil. Preferably the spacer is in simultaneous, thermal contact with substantially an entire axial length of the cylindrical inner surface of the Cavity and with substantially an entire, axial length of the cylindrical outer surface of the Heat pipe. Suitably, the fuser roll, the spacer and the heat pipe made of aluminum. Ideally, the melting roll made of a thermally conductive material having a first Hardness coefficient has, wherein the spacer part of a thermally conductive material which has a second and lower hardness coefficient owns, and where the heat pipe is made of a thermally conductive material, which is a third and lowest degree of hardness shows.

According to one Second aspect of the present invention is a Aufschmelzrollenanordnung The invention relates to a cylindrical melting roll comprising forms an axial cavity; a heat pipe, the axially opposite Has sealed ends, forming an evacuated, hollow inner chamber, which is durable under a vacuum; an electrically conductive coil, the spiral around an axial length a cylindrical outer surface of the heat pipe is wrapped around; and wherein the heat pipe and the coil are coaxial within the hollow, axial interior with the coil between an inner peripheral surface the melting roll and the cylindrical outer surface of the heat pipe are positioned.

According to one Third aspect of the present invention is a Aufschmelzrollenanordnung The invention relates to a cylindrical melting roll comprising provides an axial cavity; a heat pipe, the axially opposite Ends, sealed, owns, providing an evacuated chamber, which is durable under a vacuum; an electrically conductive coil, the spiral around an axial length a cylindrical outer surface of the heat pipe is wound; a spacer which spirals around the cylindrical outer surface of the heat pipe is wound between successive turns of the coil, with each of the successive turns, axially from each other spaced, held; and wherein the heat pipe, the coil and the Spacer coaxially within the axial hollow space with the coil and the spacer between an inner peripheral surface of the Melting roller and the cylindrical outer surface of the heat pipe are positioned.

According to a fourth aspect of the present invention, there is provided a method of making a fuser roll assembly comprising: forming a cylindrical fuser roll having a central, axially oriented interior cavity; Forming a heat pipe having an inner chamber; Insert the heat pipe into the fuser roll to co-locate the heat pipe coaxially within the interior cavity an electrically conductive heating coil wound in a spiral shape having a plurality of axially spaced turns to place a central axial length of a cylindrical outer surface of the heat pipe; Evacuating the inner chamber; partially filling the inner chamber with an amount of a working fluid; hermetic sealing of the inner chamber; and forming an electrical connection across the heating coil.

Preferably the method further comprises forming the fuser roll with the inner cavity having a first inner diameter; Wrap the heating coil so as to make a second outer diameter larger than to show the first diameter before the heating coil enters the internal cavity is used; Reducing the second diameter during the onset; and releasing the heating coil to the second diameter to accept after insertion.

Preferably the method has an axial spacing between them following turns of the coil; and interposing a spacer a thermally conductive material between the successive ones Turns of the coil; on.

Preferably the method has an axial spacing from each other following turns of the coil; and interposing a spacer a thermally conductive material between the successive ones Windings of the coil, with the spacer in simultaneous, thermal Contact with substantially an entire axial length of one cylindrical inner surface the cavity and with substantially a total axial length of the cylindrical outer surface is; on.

For a better one understanding of the invention, and to show how embodiments thereof are implemented can be Reference will now be made, by way of example, to the accompanying schematic Drawings taken in which:

1 Fig. 12 is a perspective view of a general electrophotographic image forming apparatus;

2 Fig. 10 is a sectional view of a conventional fusing roller assembly of an electrophotographic image forming apparatus;

3 Fig. 12 illustrates the structure of a fixing unit of an electrophotographic image forming apparatus employing a conventional fuser roll assembly;

4 Fig. 12 illustrates the structure of a fixing unit of an electrophotographic image forming apparatus employing a different conventional melting roll arrangement;

5 Fig. 12 is a cross-sectional view of a fixing unit of an electrophotographic image forming apparatus employing a first embodiment of a fuser roll assembly constructed in accordance with the principles of the present invention;

6 shows a partial perspective view of the structure of the Aufschmelzrollenanordnung shown in 5 although without representation of details of the heat pipe;

6A shows a partially cutaway detailed cross-sectional view of a resistance heating coil, shown in FIG 6 ;

6B . 6C and 6D Figures 1-5 illustrate a sequence of steps in the construction of a fuser roll assembly in accordance with the principles of the present invention;

7 shows a cross-sectional view showing the internal structure of the Aufschmelzrollenanordnung shown by the 5 and 6 , shows;

8th FIG. 12 is a cross-sectional view showing in detail an operation mode of the embodiment shown in FIG 7 , shows;

9 Fig. 12 shows a two-coordinate graph illustrating a change in temperature as a function of time;

10 shows a cross-sectional view of a second embodiment of a Aufschmelzrollenanord tion, constructed in accordance with the principles of the present invention;

11 shows a partial longitudinal sectional view illustrating a detail X, the fuser roller assembly, represented by 10 , describes;

12 shows a cross-sectional detail showing an operating mode of the embodiment, represented by 10 , shows;

13 Fig. 12 is a two-coordinate graph showing the change in temperature as a function of time;

14 Fig. 12 is a graph showing the phase change of a working fluid, shown as a function of the temperature rise, and the heat pipe operating period of the heat pipe;

15 represents the internal structure of the heat pipe and the heat transfer indicated so as to indicate the liquid-vapor phase change;

16 Fig. 4 is a graph illustrating saturation pressure variations as a function of saturation temperatures for Fluorinert (TM) Electronic Liquid FC-40 and distilled water used separately as a working fluid;

17 FIG. 11 is a graph of ultimate tensile variations as a function of temperature variations for the heat pipe materials of aluminum, copper and 304 stainless steel; FIG.

18A and 18B show graphs showing the maximum allowable stress and the maximum stress variations on the wall of the heat pipe with respect to temperature variations when FC-40 and distilled water are each used as a working fluid;

19A and 19B Fig. 10 is graphs showing the maximum voltage variations with respect to heat pipe thickness (T) variations when FC-40 and distilled water are each used as a working fluid; and

20 and 21 Figure 12 is a graph showing temperature variations in the center of the fuser roll with respect to time for the first embodiment of the fuser roll assembly described above.

1 Fig. 11 illustrates a general electrophotographic image forming apparatus wherein an electrophotographic image forming apparatus is a paper ejecting apparatus 1 , a keypad 2 , a control panel cover 3 , an opening button 4 for the top cover, a paper display window 5 , a multipurpose paper feeding tray 6 , a paper cassette 7 , an optional cassette 8th and an auxiliary paper carrier 9 includes.

2 Fig. 12 is a cross-sectional view of a conventional fuser roll assembly of an electrophotographic image forming apparatus using a halogen lamp as a heat source. 3 shows a sectional view of the Aufschmelzrolle the 2 with the halogen lamp as a heat source and a pressure roller used in the conventional electrophotographic image forming apparatus. As 2 shows includes the conventional Aufschmelzrollenanordnung 10 a cylindrical melting roll 11 and a heat generator 12 , such as a halogen lamp, within the fuser roll 11 , Because the outer surface of the melting roll 11 Heat must be generated, the melting role 11 from the inside by radiant heat from the heat generator 12 heated.

As 3 shows is a pressure roller 13 below the melting roll 11 arranged, which is a coated layer 11a formed of Teflon. The pressure roller 13 is elastic by a spring arrangement 13a worn to the printing paper 14 that between the melting roll 11 and the pressure roller 13 passes, against the Aufschmelzrolle 11 to press with a predetermined force. When the printing paper 14 a toner image 14a in a powder form between the fuser roll 11 and the pressure roller 13 carries, the printing paper is 14 hot-pressed with the predetermined force. In other words, the toner image becomes 14a on the printing paper 14 by the heat and power of the melting roll 11 and the pressure roller 13 melted and fixed.

A thermistor 15 is used to determine the surface temperature of the melting roll 11 to seize and to convert it into an electrical signal, and a thermostat 16 for interrupting the power supply to the heat generator 12 , such as a halogen lamp, are adjacent to the fuser roll 11 Installed. When the surface temperature of the melting roll 11 exceeds a predetermined threshold, the thermostat interrupts 16 the electrical energy to the heat generator 12 , The thermistor 15 detects the surface temperature of the melting roll 11 and transmits the result of the detection to a control unit (not shown) for the printer. The control unit controls the energy supply to the halogen lamp of the heat generator 12 corresponding to the detected surface temperature of the melting roll 11 to keep the surface temperature within a given range. The thermostat 16 serves as a thermal protector for the fuser roll 11 and the neighboring elements, which then works when the thermistor 15 and the control unit fail to match the temperature of the fuser roll 11 to control.

A conventional refining roller assembly which uses the halogen lamp as a heat source unnecessarily consumes a large amount of power and requires a very long warm-up period when the image forming apparatus is turned on for image formation. In other words, after the application of energy, a standby period follows until the temperature of the melting roll 11 reaches a set temperature for a few tens of seconds to a few minutes. For the conventional fuser roll assembly, since the fuser roll is heated by radiant heat from the heat source, the heat transfer rate is low. In particular, compensation for temperature variations due to a drop in the temperature of the heating roller caused by contact with the printing paper is delayed so that it is difficult to uniformly distribute the temperature of the fusing roller 11 to control. Especially in a standby mode where the operation of the printer is suspended, power must be applied periodically to keep the temperature of the fuser roll constant, thereby causing unnecessary power consumption. Also, it takes a considerable amount of time to switch the standby mode to an operation mode for image output, so that the resulting image can not be outputted quickly.

4 Fig. 11 is a sectional view of a conventional fuser roll assembly used in an electrophotographic image forming apparatus. A hotplate 22 is in a lower portion of a flexible, cylindrical film tube 21 arranged, and a pressure roller 23 is below the heating plate 22 attached. The film tube 21 is rotated by a separate turntable and is local to a part between the heating plate 22 and the pressure roller 23 heated and deformed. This method of locally heating the film tube 21 through the heating plate 22 is advantageous in terms of low energy consumption. However, the local heating method is unsuitable for high-speed printing.

A fixing unit of an electrophotographic image forming apparatus employing a first embodiment of a fuser roll assembly according to the present invention is disclosed in U.S.P. 5 shown while 6 a perspective view of 5 showing the structure of the Aufschmelzrollenanordnung in more detail, and 7 shows a longitudinal sectional view of the Aufschmelzrollenanordnungen the 5 and 6 ,

As the 5 . 6 and 6A show together, includes the fuser 200 a melting roll arrangement 210 , which turns in one direction, in which a printing paper 250 that is a toner image 251 carries, is ejected, ie in a clockwise direction, seen from the point of view of 5 , and a pressure roller 220 in the counterclockwise direction in contact with the Aufschmelzrollenanordnung 210 rotates. The melting roll arrangement 210 comprises a cylindrical melting roll 212 which has an outer, cylindrical protective layer 211 which is formed on the surface thereof by coating with Teflon, and a heat generator 260 who is in the meltdown role 212 is installed. A thermistor 230 for detecting the surface temperature of the melting roll 212 is at the top of the melting roll 212 attached.

The heat generator 260 is within the melting roll 212 installed to generate heat using energy supplied from an external power supply unit (not shown). The heat generator 260 has an inner heat pipe 262 that within the multiple coils of the heating unit 213 installed, both ends 264 of the heat pipe 262 hermetically sealed to maintain a predetermined pressure. The inner heat pipe 262 takes a working fluid 214 under a predetermined volume amount.

The thermistor 230 for detecting the surface temperature of the melting roll 212 and the protective layer 211 is above the melting roll 212 in contact with the protective layer 211 Installed. A thermostat 240 for interrupting the power of a power supply unit when the surface areas temperature of the melting roll 212 and the protective layer 211 is rising fast, is also above the melting roll 212 Installed.

The heating unit 213 is supplied with power from the external power supply unit to generate heat. The heating unit 213 is made of a spiral resistance heating coil, which is the inside of the melting roll and the outside of the inner heat pipe 262 touched, built up.

A thermistor 230 is in direct, physical contact with the protective layer 211 and detects the temperature of the protective layer 211 , The inner space formed by the inner, cylindrical cavity 242 the melting roll 212 , is through the heat generator 260 busy. The heating unit 213 For example, a spiral winding of a plurality of turns made of a spiral resistance heating coil installed along the inner cavity 242 in direct, physical contact with the inner, cylindrical wall of the fuser roll 212 , be. The heating unit 213 includes a heat-generating wire 213a formed of an electrical resistance material, such as an iron-chromium (Fe-Cr) or nickel-chromium (Ni-Cr) coil, and an electrically insulating cover layer 213c formed of an electric dielectric material such as magnesium oxide (MgO) protects the heat generating wire 213a , An insulating cover layer 213b the heating unit 213 prevents deformation or characteristic changes in the heat generating wire 213a that occur easily over time or due to temperature variations in a working fluid 214 caused, which will be described later. An outer layer 213b made of a relatively inert material, such as stainless steel, forms a protective layer around the insulating layer 213c around. Both ends of the heating unit 213a are not through the cover layer 213b covered to electrical contacts 215 at both ends of the melting roll 212 to build. Each end of the cover layer 213b is through a seal 213d completed to prevent the dielectric layer 213c , formed from MgO, is exposed to air. Preferably, the seal 213d is formed of a zirconia (ZrO ₂ ) ceramic to improve heat resistance, corrosion resistance and durability. Preferably, the resistance of the heating unit 213 25-40 Ω with respect to 220 V AC and 5-20 Ω with respect to 110 V AC.

As in the 6B . 6C and 6D is shown, the distance between diametrically opposed inner walls of the inner cylindrical surface 246 the melting roll 214 d ₁ , while the outer, cylindrical surface of the multiple turns of the heating unit 213 has a diameter of d ₂ . How through 6B is shown, is the heating unit 213 spirally in multiple turns of a helix about substantially the entire axial length of the outer cylindrical surface of the heat pipe 262 wound. The average outer cylindrical diameter of the multiple turns of the heating unit 213 is d ₂ , which is slightly larger than d ₁ . As in 6C are shown, opposing, axially directed forces F to electrodes 215 at axially opposite ends of the coil 213 Applied to the diameter of the coil 213 to decrease to a value that is less than d ₁ while the heat pipe 262 together with the heating unit 213 coaxial with the internal cavity 242 the melting roll 212 is used. As in 6D With the force F removed, the outer surfaces of each loop of the coil stand 213 in direct, physical and thermal contact with the outer peripheral surface 246 the melting roll 212 ; thereby allowing the removal of the force F of the coil 213 in that it defines the outer, cylindrical diameter d ₁ , equal to the inner diameter of the melting roll 212 , assumes. The divisions x ₁ , x ₂ between adjacent loops of the coil 213 are not necessarily the same. The one important thing, though, is that most or all of the outer surface of each loop of the coil 213 in direct, physical and thermal contact with the cylindrical inner surface 246 the melting roll 212 lies.

Then, as by the transition between the 6C and the 6D is shown, if once the heat generator 260 inside the inner cavity 242 the melting roll 212 is installed, air pressure to the inside of the heat pipe 262 applied to the cylindrical wall of the heat pipe 262 expand radially outward until the inner surfaces of the heating unit 213 essentially in direct, physical contact with the cylindrical outer surface of the heat pipe 262 and simultaneously in direct, physical and thermal contact with the inner cylindrical surface 246 the melting roll stand. The inner cavity of the heat pipe 262 is then with a predetermined amount of a working fluid 214 filled and the heat pipe 262 is hermetically sealed under a predetermined pressure.

The working fluid 214 is in a sealed, inner space of the heat pipe 262 contained, wherein the heat generator is installed around the cylindrical outer side thereof. The working fluid 214 is in an amount of 5-50% by volume, and preferably 5-15% by volume based on the internal volume 268 of the heat pipe 262 contain. The working fluid 214 prevents local variations in surface temperature rotating melting roll 212 otherwise due to the presence of the heating unit 213 may occur based on the principles of a heat pipe, and serves as a thermal medium capable of uniformly heating the entire cylindrical volume of the heat pipe 262 , and at the same time the melting roll 212 within a shorter period of time than is currently possible with conventional devices. If the amount of working fluid 214 less than about 5% by volume based on the volume of the fuser roll 212 is a dehydration phenomenon easily occurs in which the working fluid is not completely evaporated, and liquefaction immediately after evaporation should otherwise have occurred.

The heat pipe 262 can be made of stainless steel (such as Allegheny Ludlum Stainless Steel Chromium-Nickel 304SS), or copper (Cu). If the heat pipe 262 is made of stainless steel, most known working fluids except for water (distilled water) can be used. Fluorinert (TM) Electronic Liquid FC-40 (available from 3M Corporation) is the most preferred alternative to water as a working fluid 214 and is referred to here as FC-40. It can, if the heat pipe 262 is formed of copper, almost all known working fluids are used. Water (eg, distilled water) is the most preferred working fluid for the heat pipe 262 made of copper.

As 7 shows are end caps 264 with both axially opposite ends of the heat pipe 262 connected to the inner, cylindrical cavity of the heat pipe 262 seal and thereby a vacuum tight sealed interior 268 to build. The axially opposite terminal ends of the coil 213 form electrodes 215 that extends axially across the heat pipe 262 extend to operatively engage electrical contacts, such as slip rings (not shown), which in turn conduct electrical current through the coil 213 to lead. Non-conductive bushes and gear hub caps may also be attached to the outer cylindrical surface of the fuser rollers. The electrodes 215 are electrically with electrically conductive end wires of the heating coil 213 the heat megenerators 260 connected. Although the electrical connection, the structure of the heating coil 213 and the electrodes 215 Connected to a source of electrical energy, not shown in greater detail, this structure can be easily performed.

During operational use, the fuser roll assembly becomes 210 having the structure as described above, rotated by a separate rotary unit. Additional parts may be installed for this purpose. For example, a gear connecting cap is an additional part to be connected to a rotating spur gear required for the refining roller assembly 210 to turn.

In a fuser unit 200 The electrophotographic image forming apparatus constructed in accordance with the principles of the present invention generates when an electric current enters the heating coil 213 over the electrodes 215 flows, ie from an electrical power supply, the heating coil 213 Heat due to resistance heating when the electric current through the spiral coil 213 of the heat generator 260 flows, and the melting roll 212 is heated from the inside by the resulting heat. At the same time the working fluid 214 that in the heat pipe 262 is contained, evaporated by the heat. The heat generated by the spiral coil 213 , is applied to the cylindrical wall of the melting roll 212 transferred, and at the same time the body of the melting roll 212 uniformly heated by the vaporized working fluid. As a result, the surface temperature of the melting roll reaches 212 a desired reflow temperature within a much shorter period of time.

A wick 244 made of a perforated layer or a sieve of metal made of copper or stainless steel is formed in a cylindrical shape to serve as a capillary; the wick 244 can along the inner peripheral surface 266 of the heat pipe 262 to be placed. Suitable materials for the heat pipe 262 are listed in Table 2. FC-40 or water (distilled water) previously described or the materials listed in Table 3 may be used as the working fluid 214 be used. If water (distilled water) as working fluid 214 is selected, the Aufschmelzrollenanordnung can be performed at low cost without environmental problems. When the temperature of the melting roll 212 reaches a target reflow temperature at which the toner image is melted, the toner image is transferred to the printable paper (permanently applied thereto). If the printable paper to which the toner image has been transferred, the heat from the Aufschmelzrolle 212 absorbed, the vaporized working fluid goes back to its liquid phase within the cavity 268 of the heat pipe 262 above. The liquefied working fluid can then be redone by the heat generator 260 heated to evaporate, allowing the temperature of the melting roll 212 can be maintained at a predetermined temperature.

If the melting temperature of the toner is in the range of 160-180 ° C, the fuser roll assembly constructed according to the present invention can reach the target temperature within about ten seconds. Then, the surface temperature of the melting roll becomes 212 by intermittently applying an electric current to the heating unit 213 within a predetermined temperature range through the thermistor 230 depending on the surface temperature of the melting roll 212 detected by the thermistor 230 , maintained. If the thermistor 230 and a controller fail to control the surface temperature so that the surface temperature of the fuser roll 212 suddenly rises, a thermostat detects 240 disposed in close operative proximity to the cylindrical surface of the fuser roll 212 , the surface temperature of the melting roller 212 and stops the supply of electric current to the coil 213 to prevent overheating. The energy supply process can be varied depending on the target temperature. It will be appreciated that the power supply operation is controlled by such control techniques as periodic on / off or clock cycle ratio.

• (a) Präparieren eines Metallrohrs als ein Material für die Aufschmelzrolle;
• (b) Präparieren eines Metallrohrs als die Struktur für ein Wärmerohr;
• (c) Reinigen der freiliegenden Oberflächen des Metallrohrs und der Metallröhre durch Waschen des Metallrohrs und der Metallröhre mit destilliertem Wasser oder einer flüchtigen Flüssigkeit;
• (d) Reinigen der freiliegenden Oberflächen einer spiralförmigen Widerstandsheizspule durch Waschen der spiralförmigen Widerstandsheizspule mit destilliertem Wasser oder einer flüchtigen Flüssigkeit;
• (e) Wickeln der spiralförmigen Widerstandsheizspule als eine spiralförmige Wicklung mit einem Außendurchmesser, der gleich zu oder geringfügig größer als der Innendurchmesser des Metallrohrs ist, in ein ringförmiges, äußeres, zylindrisches Volumen des Wärmerohrs;
• (f) Optional Einsetzen eines Dochts, gebildet als ein Zylinder, um die innere, zylindrische Fläche des Wärmerohrs auszukleiden;
• (g) Abdichten gegenüberliegender Basisenden des Wärmerohrs mit Endkappen, so dass ein Einlass für ein Arbeitsfluid verbleibt, während beide Endleitungen der Widerstandsheizwicklung, spiralförmig gewickelt um das Wärmerohr, als elektrische Leitungen dienen;
• (h) Einsetzen des Wärmerohrs, das die spiralförmig gewickelte Heizspule trägt, koaxial in den Innenraum des Metallrohrs;
• (i) Befüllen des abgedichteten Wärmerohrs mit einem inerten Gas unter hohem Druck, um schnell den zylindrischen Mantel des Wärmerohrs zu erweitern, bis entweder die Wicklungen der Heizspule einen direkten, physikalischen und thermischen Kontakt gleichzeitig mit sowohl der inneren, zylindrischen Oberfläche der Aufschmelzrolle als auch der äußeren, zylindrischen Oberfläche des Wärmerohrs vornehmen, oder, alternativ, die Trennung über den radialen Luftzwischenraum zwischen der äußeren, zylindrischen Oberfläche des Wärmerohrs und der inneren, zylindrischen Oberfläche der Aufschmelzrolle minimiert wird;
• (j) Einfüllen von Fremdgasen von dem Innenvolumen des Wärmerohrs durch Evakuieren, Heizen und Kühlen des Wärmerohrs, um Gase von dem Innenvolumen des Rohrs abzulassen, um ein Vakuum innerhalb des Innenvolumens zu erzeugen;
• (k) Einfüllen mit 5–50 Vol.-% eines Arbeitsfluids (wie beispielsweise entweder FC-40 oder destilliertes Wasser) durch einen Einlass für Arbeitsfluid in den Innenhohlraum des Wärmerohrs;
• (l) Abdichten des Einlasses für das Arbeitsfluid des Wärmerohrs;
• (m) Sprühbeschichtung der Oberfläche des Metallrohrs mit Teflon, und Trocknen und Polieren des Metallrohrs, um eine Schutzbeschichtung auf der Aufschmelzrolle zu bilden;
• (n) Einsetzen einer nicht leitenden Buchse als ein Lager in ein Ende der Aufschmelzrolle; und
• (o) Befestigen einer Zahnradbefestigungskappe, hergestellt aus Metall, wärmebeständigem Kunststoff oder Epoxidharz an einem Ende der Aufschmelzrollenanordnung.

A fuser roll assembly having the structure described in the preceding paragraphs can be made by the steps of:

• (a) preparing a metal tube as a material for the fuser roll;
• (b) preparing a metal pipe as the structure for a heat pipe;
• (c) cleaning the exposed surfaces of the metal tube and the metal tube by washing the metal tube and metal tube with distilled water or a volatile liquid;
• (d) cleaning the exposed surfaces of a spiral resistance heating coil by washing the spiral resistance heating coil with distilled water or a volatile liquid;
• (e) winding the spiral resistance heating coil as a helical coil having an outer diameter equal to or slightly greater than the inner diameter of the metal tube into an annular outer cylindrical volume of the heat pipe;
• (f) optionally, inserting a wick formed as a cylinder to line the inner cylindrical surface of the heat pipe;
• (g) sealing opposing base ends of the heat pipe with end caps so that an inlet for a working fluid remains while both end lines of the resistance heating coil spirally wound around the heat pipe serve as electrical leads;
• (h) inserting the heat pipe carrying the spirally wound heating coil coaxially into the interior of the metal pipe;
• (i) filling the sealed heat pipe with an inert gas under high pressure to rapidly expand the cylindrical jacket of the heat pipe until either the coils of the heating coil make direct, physical and thermal contact simultaneously with both the inner cylindrical surface of the fuser roll and the outer, cylindrical surface of the heat pipe, or, alternatively, the separation across the radial air gap between the outer cylindrical surface of the heat pipe and the inner cylindrical surface of the Aufschmelzrolle is minimized;
• (j) introducing foreign gases from the interior volume of the heat pipe by evacuating, heating and cooling the heat pipe to vent gases from the interior volume of the tube to create a vacuum within the interior volume;
• (k) charging 5-50 vol% of a working fluid (such as either FC-40 or distilled water) through an inlet for working fluid into the interior cavity of the heat pipe;
• (l) sealing the inlet for the working fluid of the heat pipe;
• (m) spray coating the surface of the metal tube with teflon, and drying and polishing the metal tube to form a protective coating on the fuser roll;
• (n) inserting a non-conductive bushing as a bearing into one end of the fuser roll; and
• (o) attaching a gear mounting cap made of metal, heat-resistant plastic, or epoxy resin to one end of the fuser roll assembly.

During manufacture of the fuser roll assembly, when the metallic tube is endcapped 264 at axially opposite base ends after insertion of a wick 214 If a wick is to be used, welded argon gas into the interior cavity 268 of the metal pipe is filled via the working fluid inlet for the purpose of preventing oxidation of the heat pipe. Before filling the working fluid in the heat pipe foreign gases from the internal volume 268 and the internal volume is evacuated and repeatedly heated and cooled under a vacuum so as to discharge all the gases from the inner volume of the heat pipe to thereby substantially remove any foreign substances adhering to the inner wall of the heat pipe. For example, in a method of evacuating the internal cavity 268 , the heat pipe heated to a temperature of 250 ° C with an internal pressure of forty (40) atmospheres. At room temperature, the internal cavity should be 268 a perfect print that means there should be no molecules inside the cavity 268 to be available.

The 8th and 9 illustrate the thermal mode of operation of the embodiment shown in FIG 7 , The individual turns of the heating unit 213 either heat directly the heat-melting roll 212 or the heat pipe 262 by thermal conduction, as indicated by arrows K, or indirectly heat the air space, represented by a gap A, between adjacent turns of the heating unit 213 as indicated by arrows L. Depending on the radial arrangement of the individual turns of the heating unit 213 these turns also indirectly heat either the working fluid 214 or the melting roll 212 by radiant heat, as indicated by arrows M. A temperature T ₁ , T ₃ , taken in a radial orientation to two adjacent turns of the heating unit 213 , provides a substantially identical rise time and temperature profile as this 9 is shown over both the transitional time t ₁ and the transitional time t ₂ . The temperature T ₂ measured within the gap A between these adjacent turns of the heating unit 213 , takes place at the beginning of the temperature T ₁ , T ₃ , but then delay these temperatures with a lower temperature measurement, on the transition temperature rise time t ₁ . Subsequently, during the rest period t ₂ , all three temperatures are substantially identical.

As the 10 to 13 can show an intermediate area, or a spacer 213 ' , between the heat pipe 262 and the melting roll 212 for transferring heat from the heating unit 213 and the heat pipe 262 on the melting roll 212 in a gap A between adjacent spirals of a resistance heating unit 213 , are used. Preferably, the height t _{1 * of} the spacer 213 ' equal to the height t _{2 * of} the heating unit 213 or greater to make a space E as large as the difference between the height t ₁ of 213 ' and the height t _{2 of} the heating unit 213 to build. The room E contains air, allowing heat generated by the heating unit 213 , on the melting roll 212 is transmitted as radiant heat through the air.

By using the spacer 213 ' that fills the gap A, and transferring heat from a heating coil and the heat pipe 262 on the melting roll 212 , heat conduction may be essential with the construction being carried out by the 10 . 11 and 12 as compared with a structure using only one heating coil for heat transfer, and the temperature of the entire melting roll 212 is uniformly increased to a target temperature. Accordingly, it is preferable to use a material having excellent heat conduction, especially with a group 10 On material, such as aluminum (Al), used to the spacer 213 ' to build.

The heat pipe 262 has a precisely cylindrical tube shape and is hermetically sealed at both ends. A predetermined amount of the working fluid 214 is in the inner cavity 268 of the heat pipe 262 contain. Preferably, a net-like wick structure 244 on the inside of the heat pipe 262 provided so that heat from the heating unit 213 uniform over the interior of the heat pipe 262 can be transmitted within a short time. It can be seen that various modifications for uniform heat transfer across the heat pipe 262 can be made.

The working fluid 214 is due to heat, generated and transmitted by the heating unit 213 , evaporates, and transfers heat to the melting roll 212 to thereby operate as a thermal medium, which causes a substantial difference in surface temperature across the axial length of the fuser roll 212 prevents, and the entire Aufmmelzrolle 212 warmed up in a very short time. For this operation has the working fluid 214 a volume rate of 5-50%, preferably 5-15%, with respect to the volume of the internal cavity 268 , When the volume rate of the working fluid 214 is not greater than about 5%, a probability of dehydration phenomenon is very high. Accordingly, it is preferable to avoid a structure of the working fluid 214 not exceeding 5% of the volume capacity of the cavity 268 is.

The working fluid 214 becomes according to the material of the heat pipe 262 selected. In other words, it is when the heat pipe 262 is made of stainless steel, not preferable to use water, that is, distilled water, as the working fluid 214 , With the exception of distilled water, most of the working fluids known to date can be used. It is most preferred to use FC-40 manufactured by 3M Corporation.

The 12 and 13 illustrate the thermal mode of operation of the embodiment illustrated 10 As indicated by whistle K, adjacent turns of the heating unit may 213 , depending on their radial arrangement, either the Aufschmelzrolle 212 or the heat pipe 262 and the working fluid 214 heat by direct, thermal lines. The adjacent turns can due to their close proximity to an interposed spacer 213 ' , also directly the spacer 213 ' heat as indicated by arrows L. The spacer 213 ' can also directly the melting roll 212 heat by thermal conduction. These turns of the heating unit 213 also heat, and in turn, depending on their radial arrangement, indirectly the Aufschmelzrolle 212 and the working fluid 214 as indicated by arrows M. Measurements of temperatures T ₄ , T ₅ on the surfaces of the Teflon coating 211 on the melting roll 212 , in a radial orientation in each case to a turn of the heating unit 213 and the spacer 213 ' between two adjacent turns of the heating unit 213 , are identical during both a transition period and a rest period, as determined by 13 is shown. As a result, the spacers provide nearly identical, but certainly a uniform, outer temperature of the fuser roll along its entire axial length. It should be noted that the diameter of each turn of the heating unit 213 should be about the same; however, it is likely to be slightly smaller in value than the radial cross-sectional dimension of the intermediate spacer 213 ' be.

The spacer 213 ' can be made of a type 10 of an aluminum while the melting roll 212 is made of a type 60 of an aluminum. Type 10 aluminum is more easily deformable, thus resulting in the spacer 213 ' is more flexible. If the heat pipe 262 is made of either copper or aluminum, when inflated with a high air pressure, the cylindrical shell of the heat pipe 262 be distorted and the distance part 213 ' will be deformed to the point that both the radially inner and the radially outer surface of the spacer 213 ' 10 series aluminum provides a direct, physical thermal contact simultaneously with both the outer diameter of the heat pipe 262 as well as the inner diameter of the melting roll 212 made of aluminum type 60; however, the type 60 aluminum fuser roll will not be deformed. The hardness of Type 50 aluminum is greater than that of Type 60 series aluminum, and the hardness of Type 50 and Type 60 aluminum is greater than the Type 10 aluminum hardness. The heat transfer characteristics Type 50, Type 60, and Type 10 series aluminum are essentially the same, and the electrical conductivity of Type 50, Type 60, and Type 10 aluminum are essentially identical.

• (a) Präparieren eines Metallrohrs als ein Material für die Aufschmelzrolle;
• (b) Präparieren eines Metallrohrs als die Struktur für ein Wärmerohr;
• (c) Reinigen der freiliegenden Oberflächen des Metallrohrs und der Metallröhre durch Waschen des Metallrohrs und der Metallröhre mit destilliertem Wasser oder einer flüchtigen Flüssigkeit;
• (d) Reinigen der freiliegenden Oberflächen einer spiralförmigen Widerstandsheizspule durch Waschen der spiralförmigen Widerstandsheizspule mit destilliertem Wasser oder einer flüchtigen Flüssigkeit;
• (e) Optional Einsetzen eines Dochts, gebildet als ein Zylinder, um die innere, zylindrische Oberfläche des Wärmerohrs auszukleiden;
• (f) Wickeln der spiralförmigen Widerstandsheizspule als eine spiralförmige Wicklung mit einem Außendurchmesser, der gleich zu oder geringfügig größer als der Innendurchmesser des Metallrohrs ist, in ein ringförmiges, äußeres, zylindrisches Volumen des Wärmerohrs hinein mit einem kontinuierlichen Abstandsteil aus einem thermisch leitenden Material (wie beispielsweise Aluminium vom Typ 10), das einzelne Windungen der spiralförmigen Heizwicklung trennt, zwischengefügt zwischen der äußeren, zylindrischen Oberfläche des Wärmerohrs und der inneren, zylindrischen Oberfläche der Aufschmelzrolle;
• (g) Abdichten gegenüberliegender Basisenden des Wärmerohrs mit Endkappen, so dass ein Einlass für ein Arbeitsfluid verbleibt, während beide Endleitungen der Widerstandsheizwicklung, spiralförmig gewickelt um das Wärmerohr, als elektrische Leitungen dienen;
• (h) Einsetzen des Wärmerohrs, das die spiralförmig gewickelte Heizspule trägt, koaxial in den Innenraum des Metallrohrs;
• (i) Befüllen des abgedichteten Wärmerohrs mit einem inerten Gas unter hohem Druck, um schnell den zylindrischen Mantel des Wärmerohrs zu erweitern, bis die Wicklungen des Abstandsteils einen direkten, physikalischen und thermischen Kontakt gleichzeitig mit sowohl der inneren, zylindrischen Oberfläche der Aufschmelzrolle als auch der äußeren, zylindrischen Oberfläche des Wärmerohrs vornehmen;
• (j) Einfüllen von Fremdgasen von dem Innenvolumen des Wärmerohrs durch Evakuieren, Heizen und Kühlen des Wärmerohrs, um Gase von dem Innenvolumen des Rohrs abzulassen, um ein Vakuum innerhalb des Innenvolumens zu erzeugen;
• (k) Einfüllen mit 5–50 Vol.-% eines Arbeitsfluids (wie beispielsweise entweder FC-40 oder destilliertes Wasser) durch einen Einlass für Arbeitsfluid in den Innenhohlraum des Wärmerohrs;
• (l) Abdichten des Einlasses für das Arbeitsfluid des Wärmerohrs;
• (m) Sprühbeschichtung der Oberfläche des Metallrohrs mit Teflon, und Trocknen und Polieren des Metallrohrs, um eine Schutzbeschichtung auf der Aufschmelzrolle zu bilden;
• (n) Einsetzen einer nicht leitenden Buchse als ein Lager in ein Ende der Aufschmelzrolle; und
• (o) Befestigen einer Zahnradbefestigungskappe, hergestellt aus Metall, wärmebeständigem Kunststoff oder Epoxidharz an einem Ende der Aufschmelzrollenanordnung.

A fuser roller assembly having the structure for the second embodiment described in the preceding paragraphs can be produced by the steps of:

• (a) preparing a metal tube as a material for the fuser roll;
• (b) preparing a metal pipe as the structure for a heat pipe;
• (c) cleaning the exposed surfaces of the metal tube and the metal tube by washing the metal tube and metal tube with distilled water or a volatile liquid;
• (d) cleaning the exposed surfaces of a spiral resistance heating coil by washing the spiral resistance heating coil with distilled water or a volatile liquid;
• (e) optionally inserting a wick formed as a cylinder to line the inner, cylindrical surface of the heat pipe;
• (f) winding the helical resistance heating coil as a helical winding having an outer diameter equal to or slightly greater than the inner diameter of the metal tube into an annular outer cylindrical volume of the heat pipe with a continuous spacer made of a thermally conductive material (e.g. 10) aluminum, separating individual turns of the helical heating coil, interposed between the outer cylindrical surface of the heat pipe and the inner cylindrical surface of the fuser roll;
• (g) sealing opposing base ends of the heat pipe with end caps so that an inlet for a working fluid remains while both end lines of the resistance heating coil spirally wound around the heat pipe serve as electrical leads;
• (h) inserting the heat pipe carrying the spirally wound heating coil coaxially into the interior of the metal pipe;
• (i) filling the sealed heat pipe with an inert gas under high pressure to rapidly expand the cylindrical jacket of the heat pipe until the windings of the spacer make direct, physical and thermal contact simultaneously with both the inner, cylindrical surface of the fuser roll; make outer, cylindrical surface of the heat pipe;
• (j) introducing foreign gases from the interior volume of the heat pipe by evacuating, heating and cooling the heat pipe to vent gases from the interior volume of the tube to create a vacuum within the interior volume;
• (k) charging 5-50 vol% of a working fluid (such as either FC-40 or distilled water) through an inlet for working fluid into the interior cavity of the heat pipe;
• (l) sealing the inlet for the working fluid of the heat pipe;
• (m) spray coating the surface of the metal tube with teflon, and drying and polishing the metal tube to form a protective coating on the fuser roll;
• (n) inserting a non-conductive bushing as a bearing into one end of the fuser roll; and
• (o) attaching a gear mounting cap made of metal, heat-resistant plastic, or epoxy resin to one end of the fuser roll assembly.

For a lighter one understanding the operation of the Aufschmelzrollenanardnung the present Invention becomes the heat pipe, that is assigned to the present invention. Of the Term "heat pipe" refers to a heat transfer device, the heat from a high-heat-resistant Condition to a low-heat-resistant State using the latent heat transferred to the phase change of the working fluid from its liquid Phase to its gaseous Phase is required. Because the heat pipe the phase change property of the working fluid is used, its heat conduction coefficient higher than that of any known metal. The thermal heat transfer coefficient a heat pipe, working at room temperature is a couple hundred times larger than that of either silver or copper, with a coefficient of thermal conductivity, k, from 400 W / mk.

14 Figure 4 is a graph illustrating the phase change of a working fluid as a function of a temperature rise and heat pipe operating period. Table 1 illustrates the effective heat conductivity of the heat pipe and other heat transfer materials.

Table 1

4.18 KJ of energy are required to raise the temperature of 1 kg of water from 25 ° C to 26 ° C. If the phase of the water changes from liquid to vapor without a temperature change, then 2,442 KJ of energy is required. The heat pipe transmits about 584 times more latent heat through the liquid-vapor phase change. For a heat pipe operating at room temperature, the coefficient of thermal conductivity a few hundred may be greater than that of either silver or copper, which are known as excellent thermal conductors. The thermal conductivity of a heat pipe using a liquid metal as a working fluid operates at a high temperature, which is up to 10 ⁸ W / mK.

15 FIG. 12 illustrates the internal structure of a heat pipe that employs a wick to achieve a capillary structure within the interior of the heat pipe, and illustrates its heat transfer operation in accordance with changes in liquid-to-vapor and vapor-to-liquid phases. The resistance heating coil (not separately in 15 shown) and the wick are arranged in a cylindrical shape, and are each directly fixed against the outer, cylindrical surface and directly against the inner, circumferential surface of the heat pipe. Table 2 illustrates the recommended and not recommended materials for the heat pipe for a variety of working fluids.

Table 2

table Figure 3 illustrates a variety of suitable working fluids for different ones Working temperature ranges.

Table 3

• 1) Kompatibilität mit dem Material des Wärmerohrs, das verwendet wird;
• 2) ein Arbeitsfluid, das eine geeignete Arbeitstemperatur innerhalb des Wärmerohrs besitzt; und
• 3) thermische Leitfähigkeit des Arbeitsfluids.

It has been discovered that there are several things to consider when choosing a working fluid:

• 1) compatibility with the material of the heat pipe that is used;
• 2) a working fluid having a suitable working temperature within the heat pipe; and
• 3) thermal conductivity of the working fluid.

If a heat roll type stainless steel heat roll (SUS) or copper (Cu) are suitable working fluids in terms of compatibility with the material of the heat pipe and limited to the working temperature. FC-40 has an atmosphere or a low saturation pressure at a working temperature of 165 ° C and is considered to that it is a relatively suitable material.

wobei A = 8,2594, und B = 2310, und die Temperatur T ist in Grad Celsius gemessen.FC-40 is known to be non-toxic, non-flammable and compatible with most metals. FC-40 also has zero ozone depletion potential. Accordingly, the thermodynamics of FC-40 as a working fluid, the relationship between the saturation temperature and the pressure, are expressed by Formula (1):

where A = 8.2594, and B = 2310, and the temperature T is measured in degrees Celsius.

16 Fig. 10 is a graph showing the variations of the saturation pressure with respect to the saturation temperature for FC-40 and water as a working fluid. Table 4 shows the saturation pressures of FC-40 at certain saturation temperatures obtained from 14 , dar.

Table 4

wobei ΔP die Differenz im Druck zwischen der Innenseite und der Außenseite des Wärmerohrs ist, d₀ der Außendurchmesser des Wärmerohrs ist, t₁ die Dicke des Wärmerohrs ist und t₂ die Dicke der Endkappe ist.With regard to safe operation of the heat pipe, suitable materials for the heat pipe and the thickness of its end cap are determined according to the code of the American Society of Mechanical Engineers (ie ASME), which is a safety measurement standard for pressure vessels. For example, if the thickness of a cylindrical heat pipe is within 10% of its diameter, maximum stresses applied to the wall (σ _{max (1)} ) and the semi-spherical end cap (σ _{max (2)} ) of the heat pipe are expressed as:

where ΔP is the difference in pressure between the inside and outside of the heat pipe, d _{0 is} the outside diameter of the heat pipe, t _{1 is} the thickness of the heat pipe, and t _{2 is} the thickness of the end cap.

According to the ASME code is the maximum, allowed Voltage at any temperature equal to 0.25 times the maximum ultimate tensile strength at this temperature. If the vapor pressure working fluid in the area of the heat pipe is the Temperature equal to the saturation vapor pressure of the working fluid, the difference in pressure (ΔP) being equal to the difference between the vapor pressure and atmospheric pressure is.

17 Figure 10 is a graph of final tensile strength variations for a variety of materials for the heat pipe as a function of temperature variations for three different superstructure assemblies made from aluminum (Al), copper (Cu), and 304 stainless steel (SS304) heat pipes taken through one Temperature range extending between about 0 ° C and about 500 ° C. 18A Fig. 14 is a graph showing the maximum allowable voltage and variations of the maximum stress acting on the wall of the heat pipe with respect to temperature variations when FC-40 is used as a working fluid for heat pipes made of aluminum, copper and 304 stainless steel Steel are made. 18B FIG. 12 is a graph of variations in the maximum stress acting on a wall of copper of a heat pipe with respect to temperature variations when distilled water is used as a working fluid over a temperature range that is between about 0 ° C and about. FIG 300 ° C, for heat pipes made of aluminum, copper and 304 rust free steel are constructed. As in 18A is shown, the maximum allowable stress of the stainless steel (SS304) is much greater than that of either copper or aluminum. Safe operation without working leakage of the fluid is ensured for a heat pipe and end caps constructed of stainless steel (SS304) up to a working temperature of about 400 ° C.

The 19A and 19B Figure 4 is a graph showing variations in the maximum stress acting on a copper heat pipe with respect to variations in the thickness of the pipe when FC-10 and distilled water are used as a working fluid over a temperature range different from those of greater than 150 ° C to less than 500 ° C. As in the 19A and 19B Although the thickness of the heat pipe varies from 0.8 mm to 1.5 mm for FC-10 used as a working fluid and from 1.0 mm to 1.8 mm for distilled water, though a working fluid, respectively, vary, the maximum stress acting on the heat pipe, not very much at a working temperature greater than about 165 ° C, but less than 200 ° C.

The 20 and 21 Figure 4 shows plots of temperature variations (over a range between 0 ° C and 400 ° C) measured in the center of the fuser roll with respect to time (over a period between zero and sixty-five seconds) for the first embodiment of the fuser roll assembly described above is described. The fuser roll assembly had a fuser roll made of copper and contained distilled water as a working fluid. The melting roll had a thickness of 1.0 mm, an outer diameter of 17.85 mm and a length of 258 mm. This test was conducted at a revolving rate of the 47 rpm reflow roll with a 32 Ω resistance heating coil resistance, a voltage of 200 V and a maximum power consumption of approximately 1.5 kW. The spiral resistance heating coil was in direct contact with the inner cylindrical surface of the fuser roll.

20 presents measurements of a fuser roll assembly containing distilled water as a working fluid occupying 10% of the internal volume of the fuser roll. 21 provides measurements for a fuser roll assembly containing distilled water occupying 30% of the volume of the fuser roll. As 20 For example, this prototype requires about 8 to 12 seconds to raise the temperature of the fuser roll from room temperature of about 22 ° C to a working temperature of about 125 ° C, and less than 14 seconds to reach 200 ° C. As 21 It takes about 13 seconds to raise the temperature of the fuser roll from room temperature from about 22 ° C to 175 ° C, and only about 22 seconds to reach 200 ° C.

By comparing the results of 20 and 21 It can be seen that the rate of temperature increase varies depending on the volume ratio of the working fluid contained in the sealed interior of the fuser roll. According to the results of experiments carried out under different conditions, the fuser roll is operable with an amount of working fluid occupying 5-50% of the interior of the fuser roll. The rate of temperature increase is high with only 5-15% of the volume of the reflow roll filled with the working fluid.

Compared with a conventional one Image forming apparatus with respect to the rate of temperature increase, for one Image forming device, one of the various possible Arrangements for a Melting roller assembly according to the present invention Invention, no requirement for a continuous power supply the Aufschmelzrollenanordnung during standby state. Although the energy is then supplied when the formation of an image begins, the fuser roll assembly, constructed according to the present Invention to form an image, d. H. can still melt a toner image, at a high speed, faster than today's Arrangement.

If the volume of the working fluid is more than 50% by volume the rate of a temperature increase impractically slow. This occurs if the volume of the working fluid is less than 5 vol.%, a dehydration phenomenon either on, or it will likely happen, and although due to the insufficient supply of the working fluid, so that the melting roll either does not work well or not altogether as a heat pipe works.

In a fuser roll assembly constructed in accordance with the principles of the present invention Invention, can generate electrical energy at a voltage of 90-240 volts and a frequency of 50-70 Hz, as well as higher ones Frequencies are created.

As described above, the fuser roller assembly constructed according to the present invention comprises The present invention, a heating coil and a working fluid in the body of the metallic fuser roll, which has excellent conductivity, so that the surface of the fuser roll can be heated instantaneously to a desired reflow temperature to fix toner images that have been transferred to a printing paper. As compared with a conventional fusing roller assembly of a halogen lamp type or a direct surface heating type using a palladium (Pd), ruthenium (Ru) or carbon (C) based heating unit, the fuser roll of the present invention can attain a target reflow temperature within a range achieve a shorter time period with a reduced energy consumption, and the surface temperature of the fuser roll can be uniformly maintained. The fuser roll assembly of the present invention requires neither a warm-up nor a standby period, and accordingly, any image forming apparatus such as a printer, a copying machine, or a facsimile equipped with the fuser roll assembly of the present invention does not require power supply to the fuser roll for a print ready to be. As a result, the total energy consumption of the image forming apparatus is reduced. In addition, the fuser roll assembly of the present invention is based on the principle of a heat pipe so that the temperature distribution in the longitudinal direction of the fuser roll can be uniformly controlled, thereby optimally improving the toner fusing characteristics.

In addition, can the fuser roll assembly of the present invention is simple produced on a large scale and can ensure safe operation. The parts the fuser roll assembly are available with other, commercially available Share compatible. The quality the melting roll arrangement can be easily controlled. A high-speed printer can work with the fuser roll assembly according to the present Invention executed become.

The A fuser roll assembly and the method of making the fuser roll assembly according to the present invention Invention leads to the following advantages.

First For example, the fuser roll assembly can be simple, automated operations getting produced.

Secondly are the temperature variations in the axial or longitudinal direction of the heat pipe small (within the range of ± 1 °).

thirdly For example, a high-speed printer can easily work with the fuser roll assembly accomplished become.

Fourth can the heat source and the heat pipe, which are the main elements of the Aufschmelzrollenanordnung, as a separate Units are formed so that the Aufschmelzrollenanordnung easy in big scale can be manufactured and guarantees safe operation. The Parts of the fuser roll assembly are commercial with others available Share compatible. The quality the melting roll arrangement can be easily controlled.

Fifth, is due to continuous evaporation and condensation cycles the working fluid contained in the sealed heat pipe, although the pressure inside the heat pipe is at a high temperature (an atmosphere or lower at 165 ° C for FC-40) elevated, the risk of explosion or serious deformation very much low.

While these Invention in particular with reference to preferred embodiments which has been illustrated and described will be understood by those skilled in the art It can be seen in the relevant field that various changes in the form and in details can be made in it, without the scope of the invention as defined by the appended claims is to leave.

Claims (20)

Melting roll assembly comprising: a cylindrical melting roll ( 212 ) having an axially oriented cavity ( 242 ) provides; a heat pipe ( 262 ) having opposite ends sealed forming an evacuated chamber which is durable under a vacuum coaxially positioned within the fuser roll and characterized by: an electrically conductive heating coil (10); 213 , helically wound around a cylindrical outer surface of the heat pipe, coaxially interposed between and contacting the outer cylindrical surface of the heat pipe and an inner cylindrical surface of the cavity. Melting roller assembly according to claim 1, wherein, before the introduction of the coil ( 213 ) in the cavity ( 242 ), the coil having an outer diameter greater than the inner diameter of the Aufschmelzrolle, so that at least some turns of the coil an inner cylindrical wall of the cavity with a force. Melting roller assembly according to claim 1 or 2, wherein the heat pipe 262 made of copper. Melting roll arrangement according to claim 1, 2 or 3, wherein the melting roll ( 212 ) is formed of aluminum. A reflow roller assembly according to any preceding claim, which is a working fluid ( 214 ) contained within the chamber. Melting roller assembly according to claim 5, wherein the working fluid ( 214 ) is distilled water. Melting roller assembly according to claim 5 or 6, wherein an amount of the working fluid ( 214 ) contained within the chamber is in the range of 5-50% by volume of the chamber. Melting roller assembly according to claim 5 or 6, wherein an amount of the working fluid ( 214 ) contained within the chamber is in the range of 5-15% by volume of the chamber. A reflow roller assembly according to any preceding claim, wherein: adjacent turns of the spool ( 213 ) are axially spaced from each other; and a spacer ( 213 ' ) is interposed between a thermally conductive material between the adjacent turns of the coil. A reflow roller assembly according to any preceding claim, wherein: adjacent turns of the spool ( 213 ) are axially spaced from each other; and a spacer ( 213 ' ) is interposed between a thermally conductive material between the adjacent turns of the coil, the spacer being in simultaneous thermal contact with substantially a total axial length of the inner cylindrical surface of the cavity and substantially a total axial length of the cylindrical outer surface of the heat pipe stands. Melting roller assembly according to claim 9 or 10, wherein the melting roll ( 212 ), the spacer ( 213 ' ) and the heat pipe ( 262 ) are made of aluminum. Melting roll arrangement according to claim 9, 10 or 11, wherein the melting roll ( 212 ) is made of a thermally conductive material showing a first hardness coefficient, wherein the spacer part ( 213 ' ) is made of a thermally conductive material exhibiting a second and lower hardness coefficient, and wherein the heat pipe ( 262 ) is made of a thermally conductive material showing a third and lowest degree of hardness. A method of making a fuser roll assembly, comprising: forming a cylindrical fuser roll ( 212 ) with a central, axially oriented internal cavity; Forming a heat pipe ( 262 ) having an inner chamber; and characterized by insertion of the heat pipe ( 262 ) in the melting roll ( 213 ) to heat the heat pipe coaxially inside the inner cavity with an electrically conductive heating coil ( 213 ), wound in a spiral shape, with a plurality of axially spaced turns to place a central axial length of a cylindrical outer surface of the heat pipe; Evacuating the inner chamber; partially filling the inner chamber with an amount of a working fluid ( 214 ); hermetic sealing of the inner chamber; and forming an electrical connection via the heating coil ( 213 ). The method of claim 13, further comprising: forming the fuser roll ( 212 ) with the inner cavity having a first inner diameter; Winding the heating coil ( 213 ) so as to have a second outer diameter greater than the first diameter prior to insertion of the heating coil into the inner cavity; Reducing the second diameter during insertion; and releasing the heating coil ( 213 ) to accept the second diameter after insertion. A method according to claim 13 or 14, wherein the amount of a working fluid ( 214 ), contained within the heat pipe, in the range of 5-50% by volume of the inner chamber. A method according to claim 13 or 14, wherein the amount of a working fluid ( 214 ), contained within the heat pipe, in the range of 5-15% by volume of the inner chamber. A method according to any one of claims 13 to 16, further comprising: axial spacing of successive turns of the coil ( 213 ); and interposing a spacer ( 213 ' ) of a thermally conductive material between the successive turns of the coil. A method according to any one of claims 13 to 16, further comprising: axial spacing of successive turns of the coil ( 213 ); and interposing a spacer ( 213 ' of a thermally conductive material between the successive turns of the coil, the spacer being in simultaneous thermal contact with substantially a total axial length of a cylindrical inner surface of the cavity and with substantially a total axial length of the cylindrical outer surface. A method according to claim 17 or 18, wherein the melting roll ( 212 ) and the spacer ( 213 ' ) are made of aluminum. Process according to claim 17, 18 or 19, wherein the melting roll ( 212 ) is made of a thermally conductive material showing a first hardness coefficient, and wherein the spacer part ( 213 ' ) is made of a thermally conductive material exhibiting a second and lower hardness coefficient, wherein the heat pipe ( 262 ) is made of a thermally conductive material showing a third and lowest degree of hardness.