JPH08160793A - Fixing device - Google Patents

Abstract

PURPOSE: To provide a fixing device capable of reducing its cost, and improving the operability at the time of assembling its cost, and improving the operability at the time of assembling it by reducing the number of components and preventing the fall-off of a bearing and a gear from the fixing roller. CONSTITUTION: The T-shape locking groove 22 is disposed sideways on the end part of the fixing roller 21. Then, the projecting part 23a fitted into the locking groove is formed on the inner periphery of the driving gear 23. When the gear 23 is rotated in the peripheral direction after inserting the projecting part 23a of the driving gear 23 to the innermost part of the locking groove 22, the projecting part 23a is engaged with the cross bar section of the T-shaped locking groove 22, hence the driving gear 23 is prevented from falling-off out of the fixing roller 21. Thus, the stopper member can be eliminated which is conventionally necessitated for preventing the driving gear and the bearing from falling off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device which is mounted on an image forming apparatus such as a copying machine, a printer or a facsimile and fixes an unfixed image transferred onto a recording medium.

[0002]

2. Description of the Related Art An unfixed image (an image formed by toner made of heat-meltable resin) mounted on an image forming apparatus such as a copying machine, a printer or a facsimile and transferred onto a recording medium such as transfer paper. As a fixing device that heats and fixes a recording medium on a recording medium, a fixing roller (heating roller) having a built-in heater is brought into pressure contact with a pressure roller, and the recording medium is passed between both rollers to generate heat and pressure. A heat roller type fixing device for fixing an unfixed toner image on a recording medium is known.

In a conventional heat roller type fixing device, as shown in FIG. 7, a fixing roller 41 is supported by a frame (not shown) of the fixing device via a bearing 42.
A gear 43 for rotationally driving the fixing roller is fitted from the outside of one bearing 42. These bearings 42
The stopper 44 prevents the drive gear 43 from coming off. In addition, the positioning to the inside is generally performed by a device frame (not shown). Then, a method as shown in FIG. 8 is generally used to prevent the drive gear 43 from slipping in the rotation direction. That is, in FIG. 8 (a),
The fixing roller 41 is provided with a notch 41a at the end thereof, and the drive gear 43 is provided with a convex portion 43a on the inner periphery thereof. By fitting the two together, slip prevention is prevented and driving force is transmitted. Further, in FIG. 8B, a flat portion 51a is provided at the end of the fixing roller 51, and a flat portion 53a is also provided on the inner circumference of the drive gear 53 to prevent slippage by fitting them together. The driving force is transmitted. By the way, recently, the number of cases where a semicircular bearing is used as a bearing for supporting the fixing roller is increasing for the purpose of cost reduction.

[0004]

However, in the conventional fixing device, since the stopper is used to prevent the bearing and the gear from coming off from the fixing roller, the workability at the time of assembling is poor, There is also a problem that the stopper easily comes off. Further, there is a problem that the number of parts increases.

When the semi-circular bearing as described above is used, the semi-circular bearing and the stopper make contact (interference).
Then, there was a problem when the stopper came off easily. When a component such as a spacer is newly added in order to prevent this, there is a problem that the cost is increased and the workability at the time of assembly is reduced.

The present invention solves the above problems in the conventional fixing device, reduces the number of parts, and prevents the bearing and the gear from coming off from the fixing roller, thereby reducing the cost and improving the workability at the time of assembly. An object is to provide a fixing device capable of achieving the above.

[0007]

According to the present invention, a driving gear is fitted to one end of a fixing roller, and a driving force is transmitted to the driving gear to rotate the fixing roller. In the fixing device as described above, a protrusion is formed on the inner peripheral surface of the drive gear, and a horizontal T-shaped locking groove for locking the protrusion is provided at one end of the fixing roller. The problem can be solved by fitting the projection into the axial direction part of the locking groove and fitting into the rear circumferential direction part, and fitting the drive gear into the fixing roller.

In order to solve the above-mentioned problems, the present invention provides a drive transmission gear, which is meshed adjacent to the drive gear, with a flange, and the flange restricts the movement of the drive gear in the axial direction. Suggest to do.

Further, according to the present invention, in order to solve the above-mentioned problems, a driving gear is fitted to one end of the fixing roller, and the fixing roller is rotated by transmitting a driving force to the driving gear. In the fixing device, a flange is provided on the drive transmission gear that is meshed adjacent to the drive gear, a flange is provided on a bearing that supports the fixing roller on the opposite side of the drive gear, and the flange of the bearing is provided. It is proposed to restrict the axial movement of the drive gear and the fixing roller by means of and the flange of the drive transmission gear.

[0010]

A protrusion is formed on the inner peripheral surface of the drive gear, and a fixing groove having a T-shape for retaining the protrusion is provided at one end of the fixing roller. When fitting the drive gear to the fixing roller, first the projection of the drive gear is fitted into the axial portion of the locking groove, that is, the vertical bar portion of the T-shape, and then the circumferential portion of the locking groove, that is, T. The drive gear is prevented from coming off from the fixing roller by inserting it into the horizontal bar portion of the letter.

Other functions will be apparent from the description of the embodiments below.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing the overall structure of a laser printer to which an embodiment of the fixing device of the present invention is mounted. In this figure, the photoconductor 2 is installed at a position slightly to the right of the center of the main body of the laser printer 1. Around the photoconductor 2, a charger 3, a developing device 4, a transfer device 5, a cleaning device 6 and the like are arranged. Further, a paper feed cassette 8 is attached to the lower part of the apparatus, a paper feed roller 9 for feeding the recording papers 7 stacked in the cassette one by one, and the fed recording papers at a predetermined timing. A registration roller 10 and the like for sending out to are provided. Further, the heat roller type fixing device 1 is provided above the photoconductor 2.
1 is arranged, and a paper discharge roller pair 12 is provided on the upper left side thereof.

Although the image forming operation by the electrophotographic process is well known, its explanation is omitted. However, the toner image formed on the photoconductor 2 is transferred by the transfer device 5 onto the recording paper fed from the paper feeding cassette 8. To be done. The unfixed toner image transferred onto the recording paper is heated and fixed by the fixing roller 21 when the recording paper passes through the fixing device 11. After that, the recording paper is discharged by the paper discharge roller pair 12 to the paper discharge stacker unit 13 formed on the upper surface of the printer body cover 1a.

Inside the printer below the paper discharge stacker unit 13, an electric component unit 15 housed in a metal case 14 is provided. The electrical component section 15 includes a controller board 1
6 and various adjustment switches and control units (not shown) mounted thereon. Under the electrical component section 15, a case 19 accommodating a power source 17 and an electrical component board 18 is housed.
Is provided, and the optical device 20 is installed further below.

FIG. 2 shows a fitting portion of the fixing roller 21 of the fixing device 11 and its drive gear 23. As shown in this drawing, a notch (locking groove) 22 having a T-shape lying on its side is provided at one end of the fixing roller 21.
Further, a convex portion 23a that can be fitted into the locking groove is formed on the inner circumference of the drive gear 23. Fix the drive gear 23
When engaging with the rotor 21, first, the convex portion 23 of the drive gear 23
Align a with the T-shaped vertical rod position of the locking groove 22 and insert it in the roller axial direction. When the gear 23 is inserted into the locking groove 22 and then rotated in the circumferential direction, the convex portion 23a fits into the T-shaped horizontal bar portion of the locking groove 22, and the drive gear 23
Is prevented from coming off from the fixing roller 21. Therefore, it is possible to omit the stopper member that has been conventionally required to prevent the drive gear and the bearing from coming off.

Since the fixing roller 21 rotates in one direction during the fixing operation, the fixing groove of the fixing roller 21 can be L-shaped, but in that case. Is
When the fixing roller 21 is reversely rotated at the time of jam processing or the like, it is not prevented from coming off. However, when the T-shaped locking groove 22 is provided as in this embodiment, the retaining roller 21 is prevented from coming off even when the fixing roller 21 is reversed.

FIG. 3 shows a semi-circular bearing for supporting the fixing roller 21 on the apparatus frame. The bearing 26 shown in this figure rotatably supports the fixing roller 21 by means of a bearing (not shown) provided on the inner peripheral portion thereof. Further, a groove 27 is provided along the outer circumference of the bearing. The groove 27 is provided to prevent the bearing 26 from falling off the device frame. That is, as shown in FIG. 4, the grooves 27 of the bearing 26 are fitted into both ends of the U-shaped fixing device frame 25, and the fixing roller 21 is placed and supported on the bearing 26. Then, on one side of the fixing roller 21, the drive gear 23 is formed as described with reference to FIG.
Is fitted. Further, in this embodiment, the flange 24a is provided outside the intermediate gear 24 (outside the fixing device) for transmitting the driving force from the motor (not shown) to the driving gear 23.
Is provided. Therefore, the fixing roller 21 and the drive gear 23 are prevented from coming off from the fixing roller 21 as shown in FIG.
In FIG. 4, the fixing roller 21 cannot be moved to the right, and cannot be moved to the left in FIG. 4 by being pressed by the flange 24a of the intermediate gear 24, so that the fixing roller 21 is axially positioned. . Therefore, not only the conventional stopper on the drive gear side as described in FIG. 7 but also the stopper on the side opposite to the drive gear can be omitted.

Next, another embodiment of the present invention will be described.

In the fixing device of this embodiment, the fixing roller is
The engagement between the drive gear and the drive gear is made to prevent slippage only in the rotational direction as in the conventional example described with reference to FIG. In this embodiment, the intermediate gear adjacent to the drive gear has a flange as in the above embodiment, and the bearing on the side opposite to the drive gear has a flange as shown in FIG. To use. The bearing 36 shown in FIG. 5 is a semi-circular bearing, and a flange 36b is provided on the inner peripheral portion on the roller end side thereof. A groove 36a is provided on the outer circumference of the bearing to prevent the bearing from falling off the frame.

FIG. 6 illustrates the positioning of the fixing roller in this embodiment. As shown in this figure, a drive gear 43 or 53 is fitted to the fixing roller 41 or 51. The fixing roller 41 (51) is rotatably supported by bearings 26 and 36. Drive gear 43
The intermediate gear 24 adjacent to (53) is provided with a flange 24a, and the flange 24a allows the drive gear 43 to move.
(53) is prohibited from moving to the left. The drive gear 43 (53) is prohibited from moving to the right by the bearing 26. The fixing roller 41 (51) is shown in FIG.
Due to the configuration shown in Fig. 5, movement to the left is prohibited and the bearing 36
The rightward movement is prohibited by the flange 36b. Therefore, the fixing roller 41 (51) and the drive gear 43
(53) is prohibited from moving in the axial direction and positioned. Therefore, the stopper for preventing the drive gear and the bearing from coming off can be omitted. It should be noted that the bearings 26 and 36 are positioned and prevented from falling by inserting grooves into the tip of the frame 25.

[0022]

As described above, according to the fixing device of the present invention, since the fixing roller and the drive gear are prevented from coming off by themselves, the stopper for preventing the drive gear from coming off is omitted. It is possible to reduce costs and improve workability during assembly.

According to the structure of claim 2, since the flange is provided on the gear adjacent to the drive gear, the drive gear and the fixing roller are provided.
The movement of the drive gear to the outside is restricted, and the stopper on the side opposite to the drive gear can be omitted.

According to the third aspect of the present invention, since the drive gear can be prevented from coming off and the fixing roller can be axially positioned while the fitting portion between the drive gear and the fixing roller is the same as the conventional one. By omitting the stoppers on both sides of the fixing roller, it is possible to reduce the cost of parts and improve workability during assembly.

[Brief description of drawings]

FIG. 1 is a sectional view showing the overall structure of a laser printer equipped with an embodiment of a fixing device of the present invention.

FIG. 2 is a partial perspective view showing a fitting portion between a fixing roller and a drive gear of the fixing device.

FIG. 3 is a perspective view showing a bearing of a fixing roller of the fixing device.

FIG. 4 is a front view showing a state in which a fixing roller of the fixing device is supported.

FIG. 5 is a fixing roller according to another embodiment of the present invention.
It is a perspective view which shows the bearing of La.

FIG. 6 is a front view showing a state in which a fixing roller in the embodiment is supported.

FIG. 7 is a perspective view for explaining retaining of a fixing roller and a drive gear in a conventional fixing device.

FIG. 8 is a partial perspective view showing a fitting portion between the fixing roller and the drive gear, FIG. 8A is an example in which a locking groove is provided in the fixing roller, and FIG. Shows an example in which a flat portion is provided on the fixing roller.

[Explanation of symbols]

 1 Laser Printer 11 Fixing Device 21 Fixing Roller 22 Locking Groove 23 Drive Gear 24 Intermediate Gear 24a Flange 25 Fixing Device Frame 26,36 Bearing 36b Flange 41,51 Fixing Roller 42 Bearing 43,53 Drive Gear

Claims (3)

[Claims] 1. A fixing device in which a driving gear is fitted to one end of the fixing roller and the fixing roller is rotated by transmitting a driving force to the driving gear, the inner circumference of the driving gear. A protrusion is formed on the surface, and a horizontal T-shaped locking groove for locking the protrusion is provided at one end of the fixing roller.
The protrusion of the drive gear is fitted in the rear circumferential direction portion which is fitted in the axial direction portion of the locking groove to fix the drive gear in the fixing roller.
A fixing device characterized in that it is fitted to a la. 2. The drive transmission gear, which is meshed adjacent to the drive gear, is provided with a flange, and the flange limits the movement of the drive gear in the axial direction. Fixing device. 3. A fixing device in which a driving gear is fitted to one end of the fixing roller and the fixing roller is rotated by transmitting a driving force to the driving gear, the fixing device being adjacent to the driving gear. A flange is provided on the drive transmission gear that is meshed with each other, and a flange is provided on a bearing that supports the fixing roller on the side opposite to the drive gear. The flange of the bearing and the flange of the drive transmission gear form the drive gear and A fixing device which regulates the axial movement of the fixing roller.