JP4634846B2 - Fixing device - Google Patents

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. One typical 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 heating means (Patent Document 1). reference). 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 for solving the above technical problem has already been proposed by the present applicant, Kyocera Mita Corporation (see, for example, the specification of Japanese Patent Application No. 2003-400247). The fixing device includes a plurality of belt support rollers arranged at intervals 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 constituted by a heat roller having a built-in heating means. According to this fixing device, it is possible to shorten the heating time of the fixing roller and shorten the warm-up time without increasing the local load on the fixing roller and without impairing the durability of the fixing roller. An excellent effect can be obtained. However, the belt support roller disposed on the downstream side of the fixing roller with respect to the heat roller is rotatably supported by the pair of side walls, but the support mechanism is not specifically disclosed. There remains a technical problem to stabilize the positional relationship between the two. If the positional relationship between the belt support roller and the fixing roller is unstable, the endless belt may meander and the side edge in the width direction of the endless belt may be damaged.
Japanese Patent Laid-Open No. 11-084934

An object of the present invention is to provide a novel fixing device that stabilizes the positional relationship between a belt support roller and a fixing roller, and stabilizes the running performance of an endless belt.
Another object of the present invention is to stabilize the positional relationship between the belt support roller and the fixing roller to stabilize the traveling performance of the endless belt, and to increase the nip width of the endless belt with respect to the fixing roller to raise the fixing roller. It is an object of the present invention to provide a novel fixing device that can shorten the warming time.

According to the present invention,
In a fixing device comprising a fixing roller and a pressure roller pressed against the fixing roller,
A plurality of belt support rollers arranged at intervals from each other, and an endless belt wound around each of the belt support rollers, and one belt support roller via the endless belt with respect to the fixing roller The belt is composed of a heat roller that is pressed and rotated by a fixing roller and heated by a heating unit. The other belt support roller is downstream of the nip position with the heat roller on the outer peripheral surface of the fixing roller. Are arranged on the outer side of the fixing roller and the other belt support rollers, and are located on both outer sides in the width direction of the endless belt. Biasing means is provided for applying tension to the belt and pressing the pressure contact portions of the other belt support rollers to the pressure contact portions of the fixing roller, respectively. A partial region of the outer peripheral surface of the endless belt between the trawler and the other belt support roller is in pressure contact with a partial region of the outer peripheral surface of the fixing roller, and at least each of the pressure contact portions of the fixing roller or the other belt Any one of the press contact portions in the support roller is composed of a rotating body disposed so as to be rotatable relative to the fixing roller or the other belt support roller, respectively.
A fixing device is provided.
A pair of side walls are provided, and both end portions of the shafts of the fixing roller and the heat roller are rotatably supported via bearings between the side walls, and the urging means has one end portion that is a heat roller. A movable frame rotatably supported on each of the side walls via a shaft arranged coaxially at a position between the other belt support rollers, and supported slidably along each of the movable frames. A tension applying spring member disposed between the movable bearing, each of the movable frames, and the corresponding movable bearing to urge the movable bearing toward the other end of the corresponding movable frame, and the other in each of the movable frames A pressing force applying spring member disposed between the end portion and the corresponding side wall and biasing the other end portion of each of the movable frames toward the fixing roller, and the shaft of the other belt supporting roller. Both ends, it The other belt support roller is urged in a direction away from the heat roller by each of the tension applying spring members to apply tension to the endless belt. The pressure contact portion of the belt support roller is preferably brought into pressure contact with the pressure contact portion of the fixing roller by each of the pressure contact force applying spring members.
Each of the pressure contact portions of the fixing roller is disposed at both ends of the fixing roller so as to rotate integrally with the fixing roller, and each of the pressure contact portions of the other belt support roller is disposed at both ends of the other belt support roller. Each of the pressure contact portions in the fixing roller is the same as the diameter of the fixing roller, and the diameter of each of the rotating bodies in the other belt support roller is equal to the diameter of the other belt support roller. It is preferable that it is formed larger.

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.

1 and 2, the fixing device according to the present invention includes a fixing roller 2, a pressure roller 4 that is pressed against the fixing roller 2 from below, and a plurality of belt supports that are spaced apart from each other. A roller, in the embodiment, two belt support rollers 6 and 8 and an endless belt 10 wound around each of the belt support rollers 6 and 8 are provided. One belt support roller 6 is composed of a heat roller that is pressed against the fixing roller 2 via an endless belt 10 and is driven to rotate by the fixing roller 2 and heated by a halogen heater H as a heating means. ing. Hereinafter, the belt support roller 6 is referred to as a heat roller 6. The other belt support roller 8 is disposed outside the outer peripheral surface of the fixing roller 2 at a position downstream of the nip position 6N with the heat roller 6. Hereinafter, the other belt support roller 8 is simply referred to as a belt support roller 8.

The fixing roller 2 and the belt support roller 8 at the outer side positions in the width direction of the endless belt 10 (both positions in the left and right direction in FIG. 2) are pressed against each other and can be rotated relative to each other. (Each has a circular outer peripheral surface). At least one of the pressure contact portions 12 of the fixing roller 2 or each of the pressure contact portions 14 of the belt support roller 8 is disposed so as to be rotatable relative to the fixing roller 2 or the belt support roller 8, respectively. It consists of a rotating body. In the embodiment, each of the pressure contact portions 12 in the fixing roller 2 is disposed on both ends of the fixing roller 2 and is disposed on the shaft 16 so as to be able to rotate integrally with the fixing roller 2 and the shaft 16. 2 has the same diameter. Each of the pressure contact portions 14 in the belt support roller 8 is composed of a roller which is a rotating body, and each of the rollers is disposed at both ends of the belt support roller 8 and rotates relative to the belt support roller 8 and the shaft 18. It is supported freely. The diameters of the rollers supported rotatably at both ends of the belt support roller 8 are the same as each other and are larger than the diameter of the belt support roller 8. In FIG. 2, a symbol W indicates a width corresponding to the paper passing area in the endless belt 10.

The fixing device includes a housing (not shown) including a pair of side walls 20 that are spaced apart from each other in FIG. Both ends of each of the shaft 16 of the fixing roller 2 and the shaft 24 of the heat roller 6 are rotatably supported by bearings 26 and 28 on the respective side walls 20. A gear 29 is disposed at one end of the shaft 16 of the fixing roller 2 so as to be able to rotate integrally. The gear 29 is drivingly coupled to an electric motor, which is a driving source, via a power transmission mechanism (both shown in FIG. Not shown).

1 to 4, in the fixing device, tension is applied to the endless belt 10 with respect to the belt support roller 8, and the pressure contact portions 14 of the belt support roller 8 are respectively connected to the pressure contact portions 12 of the fixing roller 2. An urging means 30 is provided to press-contact each of them. The partial area of the outer peripheral surface of the endless belt 10 between the heat roller 6 and the belt support roller 8 is pressed against the partial area of the outer peripheral surface of the fixing roller 2 by the urging means 30.

As shown in FIGS. 3 and 4, the urging means 30 includes a pair of a movable frame 32, a movable bearing 34, a compression coil spring 36 that is a tension applying spring member, and a pressure contact force applying spring member. The compression coil spring 38 is provided. Each of the movable frames 32 has one end (the left end in FIGS. 3 and 4) arranged coaxially at a position between the heat roller 6 and the belt support roller 8 inside each side wall 20. The shaft 20 is rotatably supported on each of the side walls 20 and extends in a direction substantially tangential to the fixing roller 2 and away from the heat roller 6 along the corresponding side wall 20. .

More specifically, each of the movable frames 32 is made of sheet metal, and has a substantially rectangular main body portion 42, an upper wall portion 44 bent at a right angle from the upper end of the main body portion 42, and the upper wall portion 44. A flange portion 46 that is bent at a right angle from the tip at the one end portion and faces the main body portion 42 in parallel with a gap is provided. In each of the movable frames 32, one end of the main body portion 42 and the flange portion 46 is rotatably supported by the corresponding side wall 20 via the shaft 40. Each of the main body portions 42 is elongated in the tangential direction in parallel to the corresponding side wall 20 at a distance. A rectangular support hole 48 is formed in each main body portion 42 of the movable frame 32 so as to extend in the longitudinal direction of the main body portion 42 (left-right direction in FIGS. 3 and 4).

The movable bearing 34 is supported in each support hole 48 of the movable frame 32 so as to be slidable in the longitudinal direction of the main body 42. Each of the movable bearings 34 has a U shape opened in the other end direction of the main body 42 (the right end direction in FIGS. 3 and 4), and guided grooves (not shown) formed in the upper and lower ends thereof correspond to the corresponding support. By being fitted to the upper and lower edges of the hole 48, the hole 48 is slidably supported. Both end portions of the shaft 18 in the belt support roller 8 are rotatably supported by the U-shaped portions of the corresponding movable bearings 34, respectively. A compression coil spring 36 is provided between one end edge (left end edge in FIG. 3) of each support hole 48 of the movable frame 32 and a U-shaped bottom side rear surface (left end face in FIG. 3) of the movable bearing 34. It is arranged. Each of the movable bearings 34 is urged toward the other end of the corresponding movable frame 32 by a compression coil spring 36 (see arrow A in FIG. 3). With this configuration, the belt support roller 8 is biased in a direction away from the heat roller 6 by each of the compression coil springs 36, and tension is applied to the endless belt 10.

Each of the compression coil springs 38 is disposed between the upper surface of the upper wall portion 44 at the other end portion of the corresponding movable frame 32 and the corresponding side wall 20, and each other end portion of the movable frame 32 is attached to It urges | biases toward the fixing roller 2 so that it may rotate clockwise in FIG. 3 around the axis | shaft 40 (refer arrow B in FIG. 3). Each side wall 20 is formed with a through-hole (not shown) for receiving each of the compression coil springs 38 and a partial region of the upper wall portion 44 at the other end of the movable frame 32. With such a configuration, each of the pressure contact portions 14 (each of the rollers 14) of the belt support roller 8 is brought into pressure contact with each of the pressure contact portions 12 of the fixing roller 2 by each of the compression coil springs 38.

In the illustrated embodiment, the diameter of the heat roller 6 is smaller than the diameter of the fixing roller 2. The diameter of the belt support roller 8 is smaller than the diameter of the heat roller 6. The diameter of each pressure contact portion 12 of the fixing roller 2 is the same as the diameter of the fixing roller 2. Further, the diameter of each pressure contact portion 14 (roller 14) of the belt support roller 8 is larger than the diameter of the belt support roller 8.

When the fixing roller 2 is driven to rotate clockwise in FIG. 1 by an electric motor (not shown), the pressure roller 4 is driven counterclockwise. At the same time, the heat roller 6 is driven to rotate counterclockwise in FIG. 1 by the fixing roller 2 via the endless belt 10. As a result, the endless belt 10 is rotated following the same counterclockwise direction. In the belt support roller 8, each of the pressure contact portions 14 (rollers 14) of the belt support roller 8 is in pressure contact with each of the pressure contact portions 12 of the fixing roller 2, but each of the pressure contact portions 14 (rollers 14). Since the belt support roller 8 is rotatable relative to the belt support roller 8, the belt support roller 8 is not driven (driven) from each of the pressure contact portions 12 of the fixing roller 2. When the halogen heater H is energized and heat generation is started, heat from the halogen heater H is transmitted from both the heat roller 6 and the endless belt 10 to the fixing roller 2, 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, a sheet (not shown) having toner transferred on one side (upper surface) is conveyed substantially horizontally from right to left in FIG. After passing through the nip portion of the pressure roller 4, the unfixed toner transferred to one side of the paper is melted and fixed on one side of the paper by the fixing roller 2.

In the fixing device according to the present invention, pressure contact portions 12 and 14 that are in pressure contact with each other and can rotate relative to each other in the width direction outer side position of the endless belt 10 in the belt support roller 8 with the fixing roller 2 are disposed. In addition, biasing means 30 is provided that applies tension to the endless belt 10 and presses each of the pressure contact portions 14 of the belt support roller 8 to each of the pressure contact portions 12 of the fixing roller 2. A partial region of the outer peripheral surface of the endless belt 10 between the heat roller 6 and the belt support roller 8 is pressed against a partial region of the outer peripheral surface of the fixing roller 2. At least one of the pressure contact portions 12 of the fixing roller 2 or each of the pressure contact portions 14 of the belt support roller 8 is disposed so as to be rotatable relative to the fixing roller 2 or the belt support roller 8, respectively. It consists of a rotating body. In the embodiment, each of the pressure contact portions 14 of the belt support roller 8 is formed of a roller that is a rotating body that is disposed so as to be rotatable relative to the belt support roller 8. The belt support roller 8 is urged in a direction away from the heat roller 6 by the compression coil springs 36 of the urging means 30, and the belt support roller 8 is urged by the compression coil springs 38 of the urging means 30. Each of the pressure contact portions 14 is configured to be brought into pressure contact with each of the pressure contact portions 12 of the fixing roller 2. As a result, tension is constantly applied to the endless belt 10 and the position of the belt support roller 8 with respect to the fixing roller 2 is always kept constant, so that sagging is effectively prevented and the endless belt 10 meanders. Is prevented and the running performance is stabilized. By stabilizing the running performance of the endless belt 10, the heat is stably supplied to the fixing roller 2. Furthermore, each of the pressure contact portions 12 in the fixing roller 2 is the same as the diameter of the fixing roller 2, and each diameter of the rotating body (roller) that is the pressure contact portion 14 in the belt support roller 8 is the belt support roller 8 Therefore, by adjusting the diameter of each rotating body (roller) that is the pressure contact portion 14 in the reduction direction, a nip region (nip nip) of the endless belt 10 with respect to the outer peripheral surface of the fixing roller 2 is formed. Width) can be expanded to the maximum, and the temperature raising time of the fixing roller 2 can be shortened.

In the above-described embodiment, each of the movable frames 32 is configured to extend linearly in a tangential direction with respect to the fixing roller 2, but extends in a substantially arc shape along the outer peripheral surface of the fixing roller 2. There are other embodiments. Further, the urging means includes a compression coil spring 36 for applying tension to the endless belt 10 and a pressure contact portion 14 of the belt support roller 8 in each of the movable frames 32, and a pressure contact portion 12 of the fixing roller 2. And a compression coil spring 38 for pressure-contacting each of them, and in each of the movable frames 32, one compression coil spring is arranged so that the spring force acts on the movable bearing 34. There is another embodiment in which tension is applied to the endless belt 10 by the resultant force, and each of the pressure contact portions 14 of the belt support roller 8 is brought into pressure contact with each of the pressure contact portions 12 of the fixing roller 2. In any of the embodiments, there is another embodiment in which a tension coil spring is used instead of the compression coil spring.

1 is a schematic configuration diagram illustrating an embodiment of a fixing device configured according to the present invention, and is a schematic configuration diagram illustrating an urging unit omitted. FIG. FIG. 2 is a schematic configuration diagram showing the fixing device shown in FIG. 1 in a developed state. FIG. 2 is a schematic configuration diagram illustrating an urging unit omitted in the fixing device illustrated in FIG. 1. FIG. 4 is a plan view of the fixing device shown in FIG. 3.

Explanation of symbols

2: Fixing roller 4: Pressure roller 6: Heat roller (belt support roller)
8: Other belt support roller 10: Endless belt 12: Press contact portion 14 of fixing roller 14: Press contact portion of other belt support roller 18: Shaft 20 of other belt support roller: Side wall 30: Energizing means 32: Movable frame 34 : Movable bearing 36: Tension applying spring member (compression coil spring)
38: Pressurizing force applying spring member (compression coil spring)
40: axis

Claims (3)

In a fixing device comprising a fixing roller and a pressure roller pressed against the fixing roller,
A plurality of belt support rollers arranged at intervals from each other, and an endless belt wound around each of the belt support rollers, and one belt support roller via the endless belt with respect to the fixing roller The belt is composed of a heat roller that is pressed and rotated by a fixing roller and heated by a heating unit. The other belt support roller is downstream of the nip position with the heat roller on the outer peripheral surface of the fixing roller. Are arranged on the outer side of the fixing roller and the other belt support rollers, and are located on both outer sides in the width direction of the endless belt. Biasing means is provided for applying tension to the belt and pressing the pressure contact portions of the other belt support rollers to the pressure contact portions of the fixing roller, respectively. A partial region of the outer peripheral surface of the endless belt between the trawler and the other belt support roller is in pressure contact with a partial region of the outer peripheral surface of the fixing roller, and at least each of the pressure contact portions of the fixing roller or the other belt Any one of the press contact portions in the support roller is composed of a rotating body disposed so as to be rotatable relative to the fixing roller or the other belt support roller, respectively.
A fixing device. A pair of side walls are provided, and both end portions of the shafts of the fixing roller and the heat roller are rotatably supported via bearings between the side walls, and the urging means has one end portion that is a heat roller. A movable frame rotatably supported on each of the side walls via a shaft arranged coaxially at a position between the other belt support rollers, and supported slidably along each of the movable frames. A tension applying spring member disposed between the movable bearing, each of the movable frames, and the corresponding movable bearing to urge the movable bearing toward the other end of the corresponding movable frame, and the other in each of the movable frames A pressing force applying spring member disposed between the end portion and the corresponding side wall and biasing the other end portion of each of the movable frames toward the fixing roller, and the shaft of the other belt supporting roller. Both ends, it The other belt support roller is urged in a direction away from the heat roller by each of the tension applying spring members to apply tension to the endless belt. The fixing device according to claim 1, wherein the pressure contact portion of the belt support roller is pressed against the pressure contact portion of the fixing roller by each of the pressure contact force applying spring members. Each of the pressure contact portions of the fixing roller is disposed at both ends of the fixing roller so as to rotate integrally with the fixing roller, and each of the pressure contact portions of the other belt support roller is disposed at both ends of the other belt support roller. Each of the pressure contact portions in the fixing roller is the same as the diameter of the fixing roller, and the diameter of each of the rotating bodies in the other belt support roller is equal to the diameter of the other belt support roller. The fixing device according to claim 1, wherein the fixing device is formed larger than the fixing device.

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