JPH05165366A - Fixing device for image forming apparatus - Google Patents

Abstract

(57) [Abstract] [Purpose] The teeth of the drive gear and the transmission gear do not wear against each other during the opening / closing operation of the upper body, and the heating roller is easily rotated during the processing of recording paper jams. A fixing device capable of performing the above is provided. [Structure] When the upper main body 9 is closed, the projecting member 26 of the upper main body 9 is brought into contact with the moving member 21 and moved to the heating roller 3 side, and the drive gear is passed through the second compression coil spring 25. 22 is moved to the heating roller 3 side and engaged with the heating roller 3. When the upper main body 9 is opened, the projecting member 26 separates from the moving member 21, so that the first compression coil spring 24 separates the driving member 22 together with the moving member 21 from the heating roller 3. As a result, the recording paper jam processing can be easily performed as in the conventional case, but the transmission gear and the drive gear 22 can be constantly in mesh with each other, and tooth wear is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an image forming apparatus using electrophotography.

[0002]

2. Description of the Related Art In recent years, printers using electrophotography have made remarkable progress. Hereinafter, the configuration of the fixing device of the conventional image forming apparatus using the electrophotographic method will be described with reference to FIG.
Will be described with reference to.

As shown in FIGS. 3A and 3B, the fixing device has a heating roller 3 which has a heating element 1 and is rotated by a drive gear 2, and is in pressure contact with the heating roller 3. The pressure roller 4, the first transmission gear 5 arranged closer to the drive source (not shown) than the drive gear 2, and the swingable swing for rotatably supporting the first transmission gear 5. Dynamic gear frame 6
A second transmission gear 7 which is provided so that its center is the swing center of the first transmission gear 5 and is closer to the drive source than the first transmission gear 5 by one, and a recording paper discharge intermediate gear 8. ing. Reference numerals 9 and 10 denote an upper body and a lower body of the image forming apparatus, 11 denotes a recording sheet, and 12 denotes a protruding member which is provided so as to project downward from the upper body 9.

In the above structure, when the upper main body 9 is closed, as shown in FIG. 3 (b), the projecting member 12 abuts on the swing gear frame 6, and the first transmission gear 5 operates in this manner. Swings to the position where it meshes with the drive gear 2
The power from the drive source is transmitted to the drive gear 2 and thereafter (after the fixing device) via the second transmission gear 7 and the first transmission gear 5.

When the upper main body 9 is opened, as shown in FIG.
As shown in (a), the projecting member 12 separates from the swing gear frame 6, and the first transmission gear 5 swings around the second transmission gear 7 in conjunction with this operation to form the drive gear 2. Do not mesh,
Power is not transmitted to the drive gear 2 and after (after the fixing device).

When the recording paper 11 is jammed in the fixing device by the above-described operation, the drive gear 2 is separated from the drive source by opening the upper main body 9, so that the heating roller 3 can be easily rotated. The jam can be easily removed.

[0007]

By the way, in such a conventional fixing device, the engagement between the drive gear 2 and the first transmission gear 5 is engaged or disengaged in association with the opening / closing operation of the upper main body 9. However, there is a problem that the teeth and teeth (mountains) of the drive gear 2 and the first transmission gear 5 wear each other every time this operation is performed.

The present invention solves the above-mentioned problem, and the teeth of the drive gear and the transmission gear do not wear against each other during the opening / closing operation of the upper main body, and the heating roller is used to jam the recording paper. It is an object of the present invention to provide a fixing device that can be easily rotated at times.

[0009]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a drive gear which is coaxially movable with a heating roller and is movable in the axial direction, and the driving gear is engaged with the heating roller. A disengagement spring that urges the engaging part of the driving gear to disengage from the engaged part of the heating roller, and forms an engaging part that engages with the driving gear. A moving member is provided that is movable in the axial direction coaxially with the heating roller and is moved to the heating roller side by abutting the protruding member of the upper body when the upper body of the image forming apparatus is closed. A pressing spring that is interposed between the moving member and the drive gear and urges the drive gear in a direction to engage the heating roller is provided, and the transmission gear and the drive gear are always in mesh with each other. is there.

[0010]

In the above structure, when the upper body is closed, the moving member is moved to the heating roller side against the releasing spring by the abutment of the projecting member of the upper body. It is moved to the heating roller side and engages with the heating roller. Therefore, the heating roller receives the driving force from the driving gear and is rotated.

On the other hand, when the upper main body is opened, the projecting member separates from the moving member, and therefore the separating spring moves the driving gear together with the moving member in the direction separating from the heating roller, cutting the driving force from the driving gear. To be done. As a result, the recording paper jam processing can be easily performed as in the conventional case.

As described above, since the driving force can be transmitted and cut by engaging and disengaging the moving member with respect to the driving gear so that the transmission gear and the driving gear are constantly in mesh with each other, wear of these teeth is prevented. Decrease.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. It should be noted that those having the same functions as those of the conventional one are designated by the same reference numerals and the description thereof will be omitted.

As shown in FIGS. 1 (a) and 1 (b) and FIGS. 2 (a) and 2 (b), a moving member 21 is disposed adjacently on the same axis as the heating roller 3. A drive gear 22 is externally fitted over the heating roller 3 and the moving member 21.
Here, the moving member 21 and the drive gear 22 are movable in the axial direction of the heating roller 3.

The drive gear 22 has a convex portion 22a as an engaging portion, and the heating roller 3 has the convex portion 22a.
A concave portion 3a is formed as an engaged portion that can be engaged with and disengaged from. Reference numeral 22b denotes a tooth portion of the drive gear 22 that is constantly meshed with the first transmission gear 5, and the first and second transmission gears 5 and 7 are fixed in position and rotatable without swinging. ..

A heating roller bearing 23 for supporting the heating roller 3
A first compression coil spring 24 for urging the drive gear 22 toward the moving member 21 is interposed between the drive gear 22 and the tooth portion 22b of the drive gear 22, and a drive is provided between the moving member 21 and the drive gear 22. A second compression coil spring 25 that urges the gear 22 toward the heating roller 3 is interposed. Here, the second compression coil spring 25 has a spring pressure larger than that of the first compression coil spring 24.

Reference numeral 26 denotes a projecting member projecting downward from the upper body 9, and when the upper body 9 is closed, the projecting member 26 abuts the moving member 21 so that the moving member 21 heats the heating roller. It is adapted to be moved to the 3 side (direction a). Here, 26a and 21a are tapered surfaces formed on the projecting member 26 and the moving member 21, 27 is a heating element electrode, and 28 is an electrode supporting member.

The operation of the above configuration will be described with reference to the drawings. When the upper body 9 is closed, as shown in FIG.
As shown in (b) and FIG. 2 (b), the projecting member 26 contacts the moving member 21 while pushing it from above, and the moving member 21 moves in the direction a. Then, in conjunction with this, the second compression coil spring 25 pushes the drive gear 22 in the a direction. The drive gear 22 pushed in the a direction fits the convex portion 22a against the first compression coil spring 24 into the concave portion 3a provided in the heating roller 3. The heating roller 3 in which the concave portion 3a and the convex portion 22a are bitten is driven by receiving a driving force from the driving gear 22. If the convex portion 22a is the concave portion 3
When it is not bitten by a, the second compression coil spring 25 absorbs the overstroke pushed by the moving member 21,
Since the spring pressure of the second compression coil spring 25 at this time is larger than the spring pressure of the first compression coil spring 24, when the drive gear 22 rotates, the drive gear is at a position where the convex portion 22a and the concave portion 3a are combined.
22 is pushed toward the heating roller 3 side and fitted, and the heating roller 3 is driven by the driving source. At this time, since the drive gear 22 only moves in the axial direction while meshing with the first transmission gear 5, wear between the tooth portion 22b of the drive gear 22 and the teeth of the first transmission gear 5 can be reduced as much as possible.

When the upper body 9 is opened, as shown in FIGS. 1 (a) and 2 (a), the projecting member 26 is removed from the upper body 9.
At the same time, it moves upward and separates from the moving member 21, and the moving member 21 is in a free state up to the electrode supporting member 28.
At this time, the drive gear 22 is pushed to the electrode support member 28 side by the first compression coil spring 24 and moved in the b direction, and the convex portion 22a provided on the drive gear 22 moves from the concave portion 3a provided on the heating roller 3 to the electrode support member 28 side. As a result, the heating roller 3 is released from the drive source as a result, and can be easily rotated. Therefore, the recording paper jam processing can be easily performed as in the conventional case. Further, since the drive gear 22 and the first transmission gear 5 are always in mesh with each other, it is possible to reduce wear of gear teeth and teeth (mountains and peaks) caused by a gear coupling method from one drive source as much as possible. it can.

[0020]

As described above, according to the present invention, while the drive gear and the transmission gear are constantly meshed with each other, the drive gear moves in the axial direction in association with the opening / closing operation of the upper body to drive the heating roller. Since the force is transmitted and cut, even if the main body is opened and closed, the wear of the drive gear of the fixing device and the transmission gear meshing with it can be reduced as much as possible with a simple structure, and the recording paper that occurs in the fixing device. It is possible to easily perform the jam clearing process as in the conventional case.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a drive gear and its vicinity when an upper main body is opened and closed in a fixing device of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view of the identification attachment device when the upper main body is opened and when the upper main body is closed.

FIG. 3 is a cross-sectional view of the conventional fixing device of the image forming apparatus when the upper main body is opened and closed.

[Explanation of symbols]

 1 heating element 3 heating roller 3a concave portion (engaged portion) 4 pressure roller 5 first transmission gear 9 upper body 10 lower body 22 drive gear 22a convex portion (engagement portion) 22b tooth portion 24 first compression coil spring ( Release spring) 25 2nd compression coil spring (pressing spring) 26 Projection member

Claims (1)

[Claims] 1. A heating roller having a heating element, a pressure roller that is in pressure contact with the heating roller, and a drive gear that rotates the heating roller when a driving force from a driving source is transmitted through a transmission gear. A fixing device disposed in the lower main body of the image forming apparatus, wherein the drive gear is disposed so as to be movable in the axial direction coaxially with the heating roller, and the drive gear is engaged with the engaged portion of the heating roller. A disengagement spring that urges the engagement part of the drive gear to disengage from the engaged part of the heating roller, and forms an engagement part that engages with the drive gear to transmit the driving force. A moving member is provided which is movable in the axial direction coaxially with the heating roller and which is moved to the heating roller side by abutting the protruding member of the upper body when the upper body of the image forming apparatus is closed. The drive gear is interposed between the member and the drive gear. The fixing device of the image forming apparatus is provided with a pressing spring for urging the heating roller in a direction to engage the heating roller, and the transmission gear and the driving gear are always in mesh with each other.