JP2005338677A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a temperature rise time of a fixing roller by sufficiently securing a driving force for an endless belt of a driving roller. <P>SOLUTION: A fixing device is provided with a fixing roller 2, a pressure roller 4, belt support rollers 6 and 8, and an endless belt 10. A partial area of the endless belt 10 is brought into pressurized contact with a partial area of the fixing roller 2, and the belt support roller 6 comprises a heat roller heated by a halogen heater 6H having a heat generation part 6HH. The belt support roller 8 comprises the driving roller, and a length 8L of the driving roller and a width 10W of the end less belt 10 are made longer than a length 6HHL of the heat generation part 6HH. Surfaces of end areas 8A and 8B placed on the outside in an axial direction of a middle area 8C having a length equal to or longer than that of the heat generation part 6HH, of the driving roller 8 are coated with silicone rubber. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a fixing device that is mounted on an image forming apparatus such as an electrostatic copying machine, a printer, or a facsimile machine and melts and fixes unfixed toner on a sheet to the sheet.

A fixing device configured to heat the fixing roller not from the inside but from the outside is already known. An example of this type of fixing device includes a fixing roller, a pressure roller that is pressed against the fixing roller, and a plurality of heat rollers that are in pressure contact with the fixing roller and incorporate a heating unit (see Patent Document 1). The fixing roller is composed of a mandrel made of an iron hollow tube and silicon rubber covering the periphery of the mandrel. Each of the heat rollers is constituted by an aluminum hollow tube whose surface is coated with a fluororesin.

Since the fixing device directly heats the surface of the fixing roller, the temperature raising time of the fixing roller can be shortened, and therefore the warm-up time can be shortened. However, since the supply of heat to the fixing roller by the plurality of heat rollers is limited to a slight nip width between each of the heat rollers and the fixing roller, the amount of heat supply is limited. As a result, when it is desired to further shorten the heating time of the fixing roller, it is necessary to widen the nip width. However, when the nip width is widened, a local load on the fixing roller increases, so that fixing is performed. The driving torque of the roller increases, and it becomes necessary to strengthen the driving system. In addition, there is a possibility that the silicon rubber of the fixing roller is damaged early and the durability is impaired.

A fixing device capable of solving the above problems has already been filed by Kyocera Mita Co., Ltd., the present applicant. An example of this fixing device is a winding roller, a pressure roller pressed against the fixing roller from below, two belt support rollers arranged at a distance from each other, and a belt support roller. And an endless belt. A part of the outer peripheral surface of the endless belt is in pressure contact with a part of the outer peripheral surface of the fixing roller. One belt support roller is composed of a heat roller with a built-in heating means. The belt support roller, which is a heat roller, and the other belt support roller are disposed on the outer side of the outer peripheral surface of the fixing roller at an upstream side and a downstream side in the rotation direction of the fixing roller, respectively. In this fixing device, a flexible endless belt is pressed against a part of the outer peripheral surface of the fixing roller to form a nip region, so that the nip width for heating the fixing roller is significantly larger than the conventional one. Can be increased. As a result, it is possible to shorten the warm-up time of the fixing device by increasing the heating time of the fixing roller without increasing the local load on the fixing roller and without impairing the durability of the fixing roller. To do.

However, it has been found that the fixing device has the following technical problems to be solved. That is, one belt support roller is composed of a driving roller that transmits rotational driving force to the endless belt, and a partial region in the circumferential direction on the inner peripheral surface of the endless belt is a part in the circumferential direction on the outer peripheral surface of the driving roller. By wrapping around the region, the rotational driving force can be transmitted from the driving roller to the endless belt. In order to efficiently transmit the heat from the heating means transmitted to the endless belt via the heat roller to the fixing roller, the outer peripheral surface of the endless belt is pressed against the fixing roller with a considerably large nip width. As described above, when the endless belt is wound around the heat roller, the belt support roller, the fixing roller, or the like, or is kept in contact with the heat roller for a long time, the heat roller, the belt support roller, or the fixing of the endless belt. There is a risk that slight deformation (with a mold) may occur in the contact portion with the roller. When such deformation occurs in the endless belt, the driving force from the driving roller to the endless belt is not sufficiently transmitted as required, slipping or the like occurs, and the running performance of the endless belt becomes uneven, and the fixing roller The contact time with is not constant. If the contact time between the endless belt and the fixing roller is not constant, heat transfer from the endless belt to the fixing roller is uneven or insufficient, causing problems such as poor fixing or a delay in the heating time of the fixing roller. Will do. As one means for preventing such problems, it is possible to increase the driving force of the driving roller with respect to the endless belt by applying a thin heat-resistant rubber to the inner peripheral surface of the endless belt or the surface of the driving roller. Conceivable. However, this means causes a problem that the heat capacity of the endless belt or the driving roller is increased and the heating time of the fixing roller is delayed. For this reason, there has been a demand for further improvement of the fixing device.
JP 11-84934 A

The object of the present invention is to ensure a sufficient driving force of the driving roller to the endless belt and to make the heat transfer from the endless belt to the fixing roller uniform so as to shorten the heating time of the fixing roller. And providing a novel fixing device.

According to the present invention,
In a fixing device including a fixing roller and a pressure roller pressed against the fixing roller,
A plurality of belt support rollers spaced from each other, and an endless belt wound around each of the belt support rollers;
A partial region of the outer peripheral surface of the endless belt is pressed against a partial region of the outer peripheral surface of the fixing roller, and at least one belt support roller is composed of a heat roller that is heated by heating means having a heat generating portion,
At least one belt support roller other than the heat roller is composed of a drive roller that transmits a rotational driving force to the endless belt, and the length of the drive roller and the width of the endless belt are formed larger than the length of the heat generating portion, Between one or both of the end regions located on the axially outer side of the intermediate region having a length equal to or longer than the heat generating portion of the drive roller and one or both regions of the endless belt corresponding to the one or both The driving force transmitting means for transmitting the driving force with less slippage between the endless belt and the intermediate region is disposed.
A fixing device is provided.
The driving force transmitting means is preferably configured by disposing a member having a friction coefficient higher than that of the surface of the intermediate region of the driving roller on both surfaces of the end region.
The driving force transmitting means reduces the surface roughness of both end regions to a surface of the intermediate region so that the friction coefficient of both surfaces of the end region of the driving roller is higher than the friction coefficient of the surface of the intermediate region. It is preferable to be formed by forming it rougher than the roughness.
It is preferable that the outer diameter of both of the end regions of the driving roller is smaller than the outer diameter of the intermediate region.
Both of the end regions of the drive roller preferably include a region where the outer diameter gradually decreases from the axially inner side to the axially outer end.
The driving force transmission means includes an annular groove formed on both surfaces of the end region of the driving roller, and annular protrusions formed on both sides in the width direction on the inner peripheral surface of the endless belt. It is preferable that a partial region in the circumferential direction of each of the annular protrusions is fitted to a partial region in the circumferential direction of the corresponding annular groove of the drive roller.
The driving force transmission means includes an annular protrusion formed on both surfaces of the end region of the driving roller, and annular grooves formed on both sides in the width direction on the inner peripheral surface of the endless belt. It is preferable that a partial region in the circumferential direction of each of the annular grooves is fitted to a partial region in the circumferential direction of the corresponding annular protrusion of the drive roller.
The driving force transmitting means includes a plurality of locking protrusions arranged at equal intervals in the circumferential direction on one or both surfaces of the end region of the driving roller, and one side portion in the width direction on the inner peripheral surface of the endless belt. Alternatively, it is composed of a plurality of locked holes formed at equal intervals in the circumferential direction on both sides, and some of the locked holes of the endless belt are fitted to the corresponding locking protrusions of the drive roller It is preferable to be locked.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a preferred embodiment of a fixing device configured according to the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIGS. 1 and 2, one embodiment of a fixing device configured according to the present invention is provided with a fixing roller 2 and a pressure roller 4 pressed against the fixing roller 2 from below, spaced apart from each other. A plurality of arranged belt support rollers 6 and 8 and an endless belt 10 wound around each of the belt support rollers 6 and 8 are provided. A part of the outer peripheral surface of the endless belt 10 is in pressure contact with a part of the outer peripheral surface of the fixing roller 2. At least one belt support roller, in the embodiment, one belt support roller 6 is composed of a heat roller heated by a heating means having a heat generating portion 6HH. In the embodiment, the belt support roller 6 is constituted by a heat roller in which a heating means 6H having a heat generating part 6HH is built, and the heating means 6H is constituted by a halogen heater having a heat generating part 6HH. When the heating means 6H is composed of a halogen heater, the heat generating part 6HH is composed of a light emitting part made of a filament.

At least one belt support roller other than the heat roller 6, in the embodiment, one belt support roller 8 is constituted by a drive roller that transmits a rotational driving force to the endless belt 10. The length 8L of the belt support roller 8 serving as a driving roller and the width (width in the left-right direction in FIG. 2) 10W of the endless belt 10 are determined by the heating unit 6HH of the heating means 6H incorporated in the belt support roller 6 serving as a heat roller. The length is larger than 6HHL. One or both of end regions 8A and 8B located on the outer side in the axial direction of the intermediate region 8C having a length equal to or longer than the heat generating portion 6HH of the belt support roller 8 as a driving roller, and an endless belt corresponding to the one or both Between the one side region or both side regions of the ten, a driving force transmitting means for transmitting the driving force with less slip to the endless belt 10 than between the endless belt 10 and the intermediate region 8C is disposed. The driving force transmission means will be described later.

The lengths (axial lengths) of the end regions 8A and 8B of the belt support roller 8 serving as a driving roller are substantially the same. The length (full length) 8L of the belt support roller 8 serving as a driving roller is a total length obtained by adding the lengths of the end regions 8A and 8B to the length of the intermediate region 8C. When the fixing device is viewed from vertically above, the fixing roller 2, the pressure roller 4, the belt support roller 6 that is a heat roller, and the belt support roller 8 that is a drive roller are each on an axis (horizontal axis parallel to each other). The center lines orthogonal to each other and passing through the centers of the endless belts 10 are arranged so as to have a common center line CL with the center line passing through the center in the width direction of the endless belt 10. The lengths of the fixing roller 2 and the pressure roller 4 are substantially the same as each other, and are substantially the same as the length 6HHL of the heat generating portion 6HH, and are slightly shorter in the embodiment. The length 6L of the belt support roller 6 which is a heat roller and the length 8L of the belt support roller 8 which is a drive roller are formed substantially the same.

The fixing device includes a housing including a pair of side walls that are spaced apart from each other in the front and back direction of the paper surface in FIG. 1 (none is shown), and includes a fixing roller 2, a pressure roller 4, and a belt support roller 6. And 8 are rotatably supported between each of the side walls and parallel to each other. One of the belt support rollers 6 and 8, in the embodiment, the belt support roller 8 that is a driving roller is pressed against the fixing roller 2 via an endless belt 10. The belt support roller 8 is formed in a nip region 10N of the endless belt 10 with respect to the fixing roller 2 formed by pressing a partial region of the outer peripheral surface of the endless belt 10 against a partial region of the outer peripheral surface of the fixing roller 2. The fixing roller 2 is disposed at the most downstream position (right end in FIG. 1) in the rotation direction (clockwise in FIG. 1).

When the fixing roller 2 is viewed in the axial direction (in FIG. 1, the paper surface is viewed from the front to the back), the virtual horizontal line passing through the axis of the fixing roller 2 is orthogonal to the x axis through the axis of the fixing roller 2 When the imaginary vertical line is the y-axis, the belt support roller 8 that is a driving roller is arranged so as to be in pressure contact with the outer peripheral surface of the fixing roller 2 through the endless belt 10 substantially in the first quadrant. Yes. On the other hand, the belt support roller 6, which is a heat roller, is located on the upstream side in the rotation direction of the fixing roller 2 with respect to the belt support roller 8 and on the downstream side in the conveyance direction of the paper P (in the second quadrant). It is arranged on the outside of the surface with a gap. The heating means 6H is supported in a stationary state between the side walls in the central region of the belt support roller 6 which is a heat roller.

The fixing roller 2 is integrally provided with a gear 2G, and the gear 2G is drivingly coupled to an electric motor M as a driving source via a power transmission mechanism (not shown) including other gears. The belt support roller 8 that is a driving roller is integrally provided with a gear 8G, and the gear 8G is engaged with the gear 2G of the fixing roller 2. The belt support roller 6, which is a heat roller, is disposed so as to be driven and rotated via the endless belt 10.

The fixing roller 2 and the pressure roller 4 are made of metal, for example, SUS or iron mandrel, solid silicon rubber or foamed silicon rubber which is an elastic member covering the mandrel, and PFA tube covering the silicon rubber or foamed silicon rubber. It can consist of Instead of the configuration in which the outer peripheral surface of the silicon rubber or the foamed silicon rubber is covered with the PFA tube, the outer peripheral surface of the silicon rubber or the foamed silicon rubber may be coated with a fluororesin that is a toner release layer. The belt support roller 6 that is a heat roller is made of a hollow tube made of metal such as SUS or aluminum, and in the embodiment, made of aluminum. The belt support roller 8 as a driving roller is made of a hollow tube made of metal such as SUS or aluminum, and in the embodiment, made of aluminum.

The driving force transmitting means includes end regions 8A and 8B that are members having a friction coefficient higher than the friction coefficient of the surface of the intermediate region 8C (that is, the surface of the aluminum hollow tube) of the belt support roller 8 as a driving roller. It is comprised by arrange | positioning on both surfaces. In the embodiment, the driving force transmission means is configured by applying or sticking heat-resistant synthetic rubber such as silicon rubber or fluorine rubber to the surfaces of both end regions 8A and 8B. Examples of the other member having a friction coefficient higher than that of the surface of the intermediate region 8C of the belt support roller 8 serving as a driving roller include ceramic powder and metal powder. The ceramic powder can be adhered to the surface in the end regions 8A and 8B of the belt support roller 8 by baking or the like, and the metal powder can be sprayed or the like. The belt support roller 8 that is a driving roller is formed to have a smaller diameter than the belt support roller 6 that is a heat roller. This is because the heat loss due to the belt support roller 8 is reduced. The endless belt 10 can be formed from polyimide resin, Ni, or SUS, but in the embodiment is formed from polyimide resin. The heating means 6H is constituted by a halogen heater, but may be constituted by other heating means, for example, an exciting coil (IH coil) for electromagnetic induction heating. The exciting coil for electromagnetic induction heating is built in the belt support roller 6 or disposed radially outside the belt support roller 6, and the belt support roller 6 is heated from the inside or the outside.

When the fixing roller 2 is rotated clockwise in FIG. 1 by the electric motor M during the fixing operation, the pressure roller 4 is driven counterclockwise. At the same time, the belt support roller 8 as a driving roller is driven to rotate by the fixing roller 4 via the gears 2G and 8G. The belt support roller 6 which is a heat roller is driven to rotate counterclockwise in FIG. When the halogen heater constituting the heating unit 6H is energized and heat generation of the heat generating part 6HH is started, heat from the heat generating part 6HH is transmitted to the endless belt 10 via the belt support roller 6 which is a heat roller. The heat transmitted to the endless belt 10 is transmitted to the fixing roller 2 in the nip region 10N, and the temperature rise of the fixing roller 2 is started. The heat transmitted to the fixing roller 2 is also transmitted to the pressure roller 4. After the surface temperature of the fixing roller 2 reaches a predetermined temperature from room temperature, the sheet P on which the toner is transferred on one side (upper surface) is conveyed substantially horizontally from right to left in FIG. After passing through the nip portion of the roller 4, the unfixed toner transferred to one side of the paper P is melted and fixed on one side of the paper P by the fixing roller 2.

In the fixing device according to the present invention, the length 8L of the belt support roller 8 serving as the driving roller and the width 10W of the endless belt 10 are formed to be larger than the length 6HHL of the heat generating portion 6HH, and the belt supporting roller 8 serving as the driving roller. , Between one or both of the end regions 8A and 8B located on the axially outer side of the intermediate region 8C having a length equal to or longer than the heat generating portion 6HH, and one or both regions of the endless belt 10 corresponding to the one or both The driving force transmitting means transmits the driving force to the endless belt 10 with less sliding than the endless belt 10 (in other words, the driving force is transmitted without substantially slipping). It is arranged.

With such a configuration, even if the endless belt 10 is slightly deformed (with a mold) as described above, the both end regions of the belt support roller 8 serving as a driving roller and the both end regions of the endless belt 10 are Since the driving force transmission means is disposed between them, slip is not substantially generated, and the driving force is sufficiently transmitted from the belt support roller 8 as the driving roller to the endless belt 10 as required. Thus, the running performance of the endless belt 10 becomes uniform, and the contact time with the fixing roller 2 is kept constant. As a result, heat transfer from the endless belt 10 to the fixing roller 2 is uniformly or sufficiently performed, and good fixing and shortening of the heating time of the fixing roller 2 are possible. Further, since it is not necessary to apply heat-resistant rubber to the entire surface of the belt support roller 8 that is a drive roller or the entire inner peripheral surface of the endless belt 10, the heat capacity of the belt support roller 8 and the endless belt 10 that are drive rollers. The problem of excessively increasing the temperature of the fixing roller 2 is also solved. That is, according to the present invention, the driving force of the belt support roller 8, which is a driving roller, to the endless belt 10 is sufficiently secured, and the heat transfer from the endless belt 10 to the fixing roller 2 is made uniform, so that the fixing roller 2. This makes it possible to shorten the heating time.

The driving force transmitting means is a member having a friction coefficient higher than the friction coefficient of the surface of the intermediate region 8C (that is, the surface of the aluminum hollow tube) of the belt support roller 8 which is a driving roller, in the embodiment, heat resistance. A synthetic rubber such as silicon rubber or fluorine rubber is disposed on both surfaces of the end regions 8A and 8B. Such a configuration does not increase the heat capacity of the endless belt 10, and does not excessively increase the heat capacity of the belt support roller 8 that is the driving roller, so that the belt support roller 8 that is the driving roller does not increase with respect to the endless belt 10. It is possible to ensure a sufficient driving force practically. The heat-resistant synthetic rubber is disposed on both surfaces of the end regions 8A and 8B, and these regions exist substantially outside the heat generating region of the heat generating portion 6HH. Therefore, the endless belt 10 and the fixing roller 2 are disposed. It is prevented that the temperature raising time is shortened.

The driving force transmission means is configured so that the friction coefficient on the surfaces of both end regions 8A and 8B of the belt support roller 8 serving as a driving roller is higher than the friction coefficient on the surface of the intermediate region 8C. There are other embodiments configured by forming both surface roughnesses to be rougher than the surface roughness of the intermediate region 8C. Specifically, both the end regions 8A and 8B are subjected to sandblasting, surface treatment with a wire brush, etching, or knurling, so that the surface roughness of both the end regions 8A and 8B is changed to the intermediate region. It can be formed to be rougher than the surface roughness of 8C. Even with this configuration, the above-described effects can be achieved.

In the fixing device, it is preferable that the outer diameters of both end regions 8A and 8B of the belt support roller 8 serving as a driving roller are smaller than the outer diameter of the intermediate region 8C. In this configuration, when a tension is applied to the endless belt 10, a restraining force against horizontal movement (movement in the axial direction that is about to come off from the belt support rollers 6 and 8) acts on both side regions of the endless belt 10. The so-called deviation of the belt 10 is suppressed and held at a stable position.

It is preferable that both end regions 8A and 8B of the belt support roller 8 serving as a driving roller include a region where the outer diameter gradually decreases linearly or in a curved shape from the axially inner side to the axially outer end. . This configuration more effectively achieves the so-called shift suppression of the endless belt 10 described above.

Referring to FIG. 3, the driving force transmission means includes an annular groove 81 formed to extend over the entire circumference of both surfaces of end regions 8A and 8B of belt support roller 8 serving as a driving roller. The annular protrusions 11 of the endless belt 10 are formed on both sides in the width direction of the inner peripheral surface of the endless belt 10 and annular protrusions 11 formed to extend along the corresponding one side over the entire circumference. There is still another embodiment in which the partial region in the circumferential direction in each of the belts is fitted to the partial region in the circumferential direction of the corresponding annular groove 81 of the belt support roller 8 that is a driving roller. In FIG. 3, only the annular groove 81 formed in the end region 8A of the belt support roller 8 that is a driving roller is shown, and the other annular groove 81 formed in the end region 8B is not shown. ing. Similarly, only the annular protrusion 11 formed on one side in the width direction on the inner peripheral surface of the endless belt 10 is shown, and the other annular protrusion 11 formed on the other side is not shown. Yes. According to this configuration, the belt support that is the drive roller is provided between both surfaces of the end regions 8A and 8B of the belt support roller 8 that is the drive roller and both sides in the width direction on the inner peripheral surface of the endless belt 10. Since a portion having a higher frictional force is formed between the intermediate region 8C of the roller 8 and the inner peripheral surface of the endless belt 10 than the corresponding intermediate region, the same as in the driving force transmitting means described above. Can achieve a positive effect.

Referring to FIG. 4, the driving force transmitting means includes an annular protrusion 82 formed on both surfaces of end regions 8A and 8B of belt support roller 8 serving as a driving roller, and an inner peripheral surface of endless belt 10. In the circumferential direction in each of the annular grooves 12 of the endless belt 10 is a corresponding annular protrusion of the belt support roller 8 that is a driving roller. There are still other embodiments that can be fitted to a partial region in the circumferential direction at 82. In FIG. 4, only the annular protrusion 82 formed in the end region 8A of the belt support roller 8 serving as a driving roller is illustrated, and the other annular protrusion 82 formed in the end region 8B is illustrated. It is omitted. Similarly, only the annular groove 12 formed on one side in the width direction on the inner peripheral surface of the endless belt 10 is shown, and the other annular groove 12 formed on the other side is not shown. According to this configuration, the belt support that is the drive roller is provided between both surfaces of the end regions 8A and 8B of the belt support roller 8 that is the drive roller and both sides in the width direction on the inner peripheral surface of the endless belt 10. Since a portion having a higher frictional force is formed between the intermediate region 8C of the roller 8 and the inner peripheral surface of the endless belt 10 than the corresponding intermediate region, the driving force transmitting means described above, particularly FIG. It is possible to achieve the same effect as in the driving force transmission means partially illustrated in FIG.

Referring to FIG. 5, the driving force transmitting means is equally spaced circumferentially on one or both surfaces (both surfaces in the embodiment) of end regions 8A and 8B of belt support roller 8 which is a driving roller. And a plurality of locking projections 83 arranged over the entire circumference, and one side or both sides (both sides in the embodiment) in the width direction on the inner circumferential surface of the endless belt 10 are equally spaced in the circumferential direction. It is composed of a plurality of locked holes 13 formed over the entire circumference, and some of the locked holes 13 of the endless belt 10 are fitted into corresponding locking protrusions 83 of the belt support roller 8 which is a driving roller. There are still other embodiments that can be locked together. In FIG. 5, only the locking protrusion 83 formed in the end region 8A of the belt support roller 8 as a driving roller is shown, and the other locking protrusion 83 formed in the end region 8B is shown. It is omitted. Similarly, only the locked hole 13 formed on one side in the width direction on the inner peripheral surface of the endless belt 10 is shown, and the other locked hole 13 formed on the other side is not shown. Has been. According to this configuration, both of the end regions 8A and 8B of the belt support roller 8 serving as a driving roller and both widthwise side portions of the inner peripheral surface of the endless belt 10 are detachably engaged with each other. Therefore, it is possible to transmit the driving force stronger and more surely than any of the previous embodiments of the driving force transmission means.

The first embodiment of the fixing device according to the present invention is configured as follows. The basic configuration is substantially the same as that of the fixing device described with reference to FIGS.
Fixing roller: An iron mandrel having a diameter of 15.0 mm is covered with a silicon sponge rubber having a thickness of 5.0 mm and an Asker C hardness of 40 °, and the surface is covered with a PFA tube (outer diameter 25.0 mm).
Pressure roller: substantially the same configuration and size as the fixing roller.
Belt support roller (heat roller): An aluminum hollow tube having a diameter of 25.0 mm and a thickness of 0.5 mm.
Heating means: a halogen heater of 1000 W, built in the heat roller.
Belt support roller (drive roller): Aluminum hollow tube having a diameter of 20.0 mm and a thickness of 0.5 mm. Silicon rubber is applied to the surfaces of both end regions.
Endless belt: made of polyimide resin having a thickness of 90 μm. The outer peripheral surface is coated or coated with PFA by a PFA tube.
Referring to FIG.
Length of fixing roller and pressure roller: 310.0 mm. Slightly longer than the maximum sheet passing width.
Length of heating part (light emitting part) of halogen heater: 320.0 mm.
Belt support roller (heat roller) length: 340.0 mm.
Endless belt width: 335.0 mm.
Total length of belt support roller (drive roller): 340.0 mm.
Length of intermediate region of belt support roller (drive roller): 325.0 mm. In this intermediate region, the surface of the aluminum hollow tube is exposed.
Length of each end region of the belt support roller (drive roller): 7.5 mm. Silicon rubber is thinly applied to the surface of each end region.
As is clear from the above-described embodiment, the partial regions in the circumferential direction on the inner peripheral surface of both side regions (each width 5.0 mm) of the endless belt are respectively corresponding end regions of the belt support roller (drive roller). Since it is wound around a partial region in the circumferential direction (the surface of the coated silicon rubber), the driving force from the belt support roller (driving roller) is firmly secured on both sides of the endless belt without substantial slippage. Therefore, the endless belt ensures stable running performance. Each end region of the belt support roller (driving roller) to which the silicone rubber is attached is substantially outside the region of the heating portion (light emitting portion) of the halogen heater. Time is prevented from being shortened.

In the fixing device having substantially the same configuration as that of the first embodiment, the material of the rubber applied to each surface of the end region of the belt support roller (drive roller) is changed to change the corresponding inner peripheral surface of the endless belt. And the driving force for the endless belt when the frictional force μF between the surface of the endless belt and the outer peripheral surface of the fixing roller is changed.
(1) When μF> μT A slip occurs between the belt support roller (drive roller) and the endless belt, the endless belt is not driven, and heat is not transmitted to the fixing roller.
(2) When μF = μT, the running performance of the endless belt is unstable, and a slight slip occasionally occurs. As a result, the temperature distribution in the rotation direction of the endless belt becomes non-uniform, and the temperature distribution in the rotation direction of the fixing roller becomes non-uniform accordingly, and a portion with poor fixability occurs during fixing.
(2) When μF <μT, the running performance of the endless belt was stabilized, and stable performance was obtained for both the temperature increase rate of the fixing roller and the fixing property.

In the above embodiment of the fixing device of the present invention, as shown in FIG. 1, the belt support roller 8 that is a driving roller is pressed against the fixing roller 2 via an endless belt 10. In this state, there is another embodiment in which the belt support roller 6 as a heat roller is pressed against the fixing roller 2 via the endless belt 10. Further, a belt support roller 6 that is a heat roller and a belt support roller 8 that is a drive roller are disposed on the outer side of the outer peripheral surface of the fixing roller 2 at intervals on the upstream side and the downstream side in the rotation direction of the fixing roller 2, respectively. There is still another embodiment in which a part of the outer peripheral surface of the endless belt pressed against a part of the outer peripheral surface of the fixing roller 2 is disposed between the belt support rollers 6 and 8.

1 is a schematic configuration diagram illustrating an embodiment of a fixing device according to the present invention. FIG. 2 is a schematic plan view of the fixing device shown in FIG. 1, and is a schematic plan view showing a heat roller, a fixing roller, and a driving roller separated from each other in a plane for easy understanding. The fragmentary sectional view which shows other embodiment of the driving force transmission means arrange | positioned between a driving roller and an endless belt. The fragmentary sectional view which shows other embodiment of the driving force transmission means arrange | positioned between a driving roller and an endless belt. The partial top view which shows other embodiment of the driving force transmission means arrange | positioned between a driving roller and an endless belt.

Explanation of symbols

2: Fixing roller 2L: Fixing roller length 4: Pressure roller 6: Belt support roller (heat roller)
6L: Belt support roller (heat roller) length 6H: Heating means (halogen heater)
6HH: heating unit 6HHL: heating unit length 8: belt support roller (drive roller)
8A: belt support roller (drive roller) end region 8B: belt support roller (drive roller) end region 8C: belt support roller (drive roller) intermediate region 8L: belt support roller (drive roller) length 10: Endless belt 10N: Nip area 10W: Endless belt width M: Electric motor P: Paper

Claims (8)

In a fixing device including a fixing roller and a pressure roller pressed against the fixing roller,
A plurality of belt support rollers spaced from each other, and an endless belt wound around each of the belt support rollers;
A partial region of the outer peripheral surface of the endless belt is pressed against a partial region of the outer peripheral surface of the fixing roller, and at least one belt support roller is composed of a heat roller that is heated by heating means having a heat generating portion,
At least one belt support roller other than the heat roller is composed of a drive roller that transmits a rotational driving force to the endless belt, and the length of the drive roller and the width of the endless belt are formed larger than the length of the heat generating portion, Between one or both of the end regions located on the axially outer side of the intermediate region having a length equal to or longer than the heat generating portion of the drive roller and one or both regions of the endless belt corresponding to the one or both The driving force transmitting means for transmitting the driving force with less slippage between the endless belt and the intermediate region is disposed.
A fixing device. 2. The fixing according to claim 1, wherein the driving force transmitting means is configured by disposing a member having a friction coefficient higher than that of the surface of the intermediate region of the driving roller on both surfaces of the end region. apparatus. The driving force transmitting means reduces the surface roughness of both end regions to a surface of the intermediate region so that the friction coefficient of both surfaces of the end region of the driving roller is higher than the friction coefficient of the surface of the intermediate region. The fixing device according to claim 1, wherein the fixing device is configured to be rougher than roughness. The fixing device according to claim 2, wherein an outer diameter of both of the end regions of the driving roller is formed smaller than an outer diameter of the intermediate region. The fixing device according to claim 4, wherein both of the end regions of the drive roller include a region where the outer diameter gradually decreases from the inner side in the axial direction to the outer end in the axial direction. The driving force transmission means includes an annular groove formed on both surfaces of the end region of the driving roller, and annular protrusions formed on both sides in the width direction on the inner peripheral surface of the endless belt. The fixing device according to claim 1, wherein a partial region in the circumferential direction of each of the annular protrusions is fitted to a partial region in the circumferential direction of the corresponding annular groove of the driving roller. The driving force transmission means includes an annular protrusion formed on both surfaces of the end region of the driving roller, and annular grooves formed on both sides in the width direction on the inner peripheral surface of the endless belt. The fixing device according to claim 1, wherein a partial region in the circumferential direction of each of the annular grooves is fitted to a partial region in the circumferential direction of the corresponding annular protrusion of the drive roller. The driving force transmitting means includes a plurality of locking protrusions arranged at equal intervals in the circumferential direction on one or both surfaces of the end region of the driving roller, and one side portion in the width direction on the inner peripheral surface of the endless belt. Alternatively, it is composed of a plurality of locked holes formed at equal intervals in the circumferential direction on both sides, and some of the locked holes of the endless belt are fitted to corresponding locking protrusions of the drive roller The fixing device according to claim 1, wherein the fixing device is locked.

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