JPH046040Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a fixing device used in an image forming apparatus applied to electrophotography.

[Prior art]

Among the so-called heat roll fixing devices used in image forming apparatuses applying electrophotographic technology, there is a fixing device that can freely place a pair of rolls, such as a pressure roll, in either a press-bond state or a detached state from the heat roll. .

FIG. 5 is a cross-sectional view of the conventional fixing device as described above. The heat roll 2 with a built-in heater 2b and the pressure roll 3 with a built-in shaft 3b in the fixing device 1 are pressed together at a predetermined pressure when fixing the unfixed toner 4a on the paper 4 by heat. It is pinched and conveyed according to the rotation of the rolls 2 and 3 in the arrow directions 2a and 3a. During the conveyance, the unfixed toner 4a on the paper 4 is fixed by heat applied by the heat roll 2 whose temperature is set to a predetermined temperature by the thermistor 9, and becomes fixed toner 4b. If the paper 4 becomes jammed for some reason, the rotation of the heat roll 2 is stopped, and the heat roll 2 and pressure roll 3 are moved as shown in the figure by a shell opening operation (not shown) or by operating a pressure release lever (not shown). The paper jam is cleared by separating the paper 4 from the paper discharge rolls 5a and 5b and pulling the paper 4 in the direction of arrow 6.

[Problems with conventional technology]

However, in the conventional fixing device 1, as shown in the figure, when the fixing operation is stopped, the heat roll 2
The pressure roll 3 separates, but the paper 4 and the heat roll 2
remains in contact with. Moreover, since the toner-adhering surface of the paper 4 is in contact with the heat roll 2, a paper jam occurs as described above, and when the jammed paper 4 is pulled out in the direction of arrow 6 and disposed of, the unfixed toner 4a is removed. It adheres to the circumferential surface of the roll 2 at the contact portion 7 between the heat roll 2 and the paper 4.

If the heat roll 2 and the pressure roll 3 are brought into pressure contact again in this state, the toner adhering to the heat roll 2 will also adhere to the circumferential surface of the pressure roll 3 again. Adhesive toner adhering to the heating roll 2 is removed by a cleaning felt 8 disposed on the circumferential surface of the heating roll 2, but adhering toner adhering to the circumferential surface of the pressure roll 3 is not cleaned and is removed next time. This will stain the back side (lower side in the figure) of the paper entering the paper.

[Purpose of invention]

In view of the above-mentioned conventional drawbacks, the present invention aims to provide a fixing device that does not stain the pressure roll or the next sheet of paper even if unfixed toner adheres to the heat roll during paper jam removal. shall be.

[Key points of the idea]

In order to achieve the above object, the present invention includes a first roller that has a built-in heat source and is in contact with the toner image side of the paper, a second roller that is in pressure contact with the first roller, and a cleaning member that cleans the surface of the first roller. The fixing device has a fixing device in which the first roller and the second roller can come into contact with and separate from each other, further comprising a rotation mechanism that rotates the first roller by a predetermined angle when a cover covering the first roller is closed. shall be.

[Example of idea]

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

FIG. 2 is an enlarged perspective view showing the main parts of the fixing device 11 according to the present invention, FIG. 3 is a side view of FIG. 2, and FIG. 1 is a side view of FIG. It is a diagram.

The fixing device 11 includes a lower pressure roll 12, an upper heat roll 13, an uppermost fixing section cover 14 that can be opened and closed, springs 15a and 15b for bringing the pressure roll 12 into pressure contact with the heat roller 13, and It is comprised of lever members 16a, 16b, etc. interposed between the springs 15a, 15b and the fixing section cover 14.

The pressure roll 12 has roll shafts 12a protruding from both end faces, and the roll shafts 12a are movably and rotatably supported by bearings of a main body frame (not shown). Further, both ends of the springs 15a and 15b are hooked into holes 17a of the fixed side cover 17,
The springs 15a, 15b are in contact with the lower surface of the roll shaft 12a, and the urging force of the springs 15a, 15b applies a force to push up the pressure roll 12.

The thermo roll 13 has a heater 13b within a roll shaft 13a protruding from a side end surface, and a thermistor (not shown) detects the surface temperature and performs temperature control. Further, a cleaning felt 28 is disposed at a position where it rubs against the circumferential surface of the heat roll 13.

The fixing section cover 14 is made of a plate-shaped material, and has an upper surface section 14a that covers the heat roll 13 from above, and a handle section 14b whose front and rear ends are bent downward. The side plate 18 is fixed at right angles to the upper surface part 14a,
A shaft hole 1 is bored near the end 18b of this side plate 18.
It is rotatably supported by a cover shaft (not shown) that fits into the cover 8a. The end 18 of this side plate 18
b is the lever member 16a, 1 below the shaft hole 18a.
It is located at a location where it comes into contact with the upper surface 19 of the upper end of the upper portion 6b. Further, when the fixing section cover 14 is in a closed state (FIGS. 2 and 3), the forward-facing lower end surface 18c of the end portion 18b abuts the upper end top surface 19 of the lever member 16, and the fixing section cover 14 is closed. As shown in FIG. 1, when the end portion 18b is in the open state with an angular displacement of approximately 60° relative to the horizontal, the rearward lower end surface 18d of the end portion 18b comes into contact with the top surface 19 of the upper tip of the lever members 16a, 16b.

Further, as shown in FIG.
While the fixing unit cover 14 is in a predetermined position with the fuser cover 14 in an open state at an angle of inclination of approximately 60° with respect to the horizontal, the lever members 16a, 16b have their upper tip top surfaces 19 facing rearward of the end portion 18b of the fixing unit cover 14. lower end surface 18 of
d, the roll shaft 12a of the pressure roll 12, the lever members 16a, 16b, the lever members 16a, 1
The upper end upper surface 19 is urged upward in the direction indicated by arrow b by a support shaft (not shown) provided in the hole 25 of 6b.

On the other hand, inside the fixing device 11, as shown in FIG. 4, there are provided a drive gear 21 for transmitting rotational force to the heat roll 13, a fixing gear 22, and a cover gear 23 that rotates when the fixing section cover 14 is opened and closed. There is. The fixing gear 22 is fixed to the roll shaft 13a described above, and as the fixing gear 22 rotates, the heat roll 13 also rotates. Further, 28 teeth are formed on the circumferential surface of the fixing gear 23.

The cover gear 23 is attached to the cover shaft 23a via a one-way bearing 23b, and 38 teeth are formed on the circumferential surface of the cover gear 23.

The drive gear 21 is attached to the drive shaft 21b via a one-way bearing 21a, and a predetermined number of teeth are formed on the circumferential surface of the drive gear 21. The driving gear 21 and the fixing gear 22, and the fixing gear 22 and the cover gear 23 are respectively disposed at positions where teeth formed on the circumferential surfaces mesh with each other. In addition, one-way bearing 2
1a is configured such that driving force is transmitted to the drive gear 21 only when the drive shaft 21b is rotated in the direction of arrow B, and the drive shaft 21 is driven by a drive device (not shown).
When a driving force is applied to 1b in the direction of arrow B, driving gear 2
1 rotates in the direction of arrow B'. Further, this rotational force is transmitted to the fixing gear 22 and rotates the heat roll 13 in the direction of arrow C via the roll shaft 13a.

The one-way bearing 23b is configured so that rotational force is transmitted to the cover gear 23 only when the cover shaft 23a rotates in the direction of arrow A. Therefore, as described above, the fixing gear 22 rotates in the direction of arrow C,
Even if the cover gear 23 rotates in the direction of arrow A', no drive is transmitted from the cover gear 22 to the cover shaft 23a.

In the fixing device of this embodiment configured as described above, processing operations when a paper jam occurs will be described below.

A paper 26 on which a toner image such as an original is formed by a transfer device (not shown) is transferred to a pressure roller 12 (shown in FIG. 1).
and the heat roll 13 are sent to the pressure contact portion 27, and conveyed by the rotation of the heat roll 13 in the direction of arrow E.
During this conveyance, the unfixed toner on the paper 26 is thermally fixed by the heat of the heater 13b within the heat roll 13.

During the fixing operation described above, for some reason the paper 26
When a paper jam occurs, a mechanism (not shown) stops the rotation of the pressure roll 12 and the heat roll 13.
Here, the operator removes the paper 26 that is jammed in the device.
To remove the fixing unit cover 14, hold the handle 14b and open it in the direction of arrow D (FIG. 1). With this operation, the end portion 18b of the side plate 18 provided on the side surface of the fixing unit cover 14 pushes down the upper end top surface 19 of the lever members 16a, 16b, and the lever members 16a,
The lower end 20 of 16b pushes down the shaft 12a of the pressure roll 12, and the pressure roll 12 and the heat roll 13
and separate them. In this embodiment, the distance t between the pressure roller 12 and the heat roller 13 when the fixing section cover 14 is completely opened (opened by 60 degrees) is 3 mm.

In this way, the pressure roll 12 and the heat roll 13
After separating the jammed paper 26, the operator pulls out the jammed paper 26 in the direction of arrow 29 (FIG. 1) and removes the paper 26 from the fixing device 11. By this pulling out (removal) process of the paper 26, the heat roll 13
Unfixed toner on the paper 26 adheres to the peripheral surface T portion of the paper 26 .

However, when the fixing section cover 14 is closed (rotated in the direction of arrow D') after the paper jam is cleared as described above, the cover shaft 23a fixed to the fixing section cover 14 shown in FIG. 4 moves in the direction of arrow A as described above. The cover gear 2 rotates through the one-way bearing 23b.
3 in the direction of arrow A'. This rotation of the cover gear 23 in the A' direction causes the fixing gear 22 to rotate in the direction of arrow C, and the roll shaft 13 is attached to the fixing gear 22.
The hot roll 13 fixed via a is rotated in the C direction. When the heat roll 13 rotates, the number of teeth of the cover gear 23 and fixing gear is 38 vs. 28, as described above.
For example, when the fixing section cover 14 is closed (rotated) by 30 degrees, the rotation angle α of the heat roll 13 is
is α=38/28×30°≒40°. This state is the first
As shown in the figure, when the fixing section cover 14 is rotated by 30 degrees in the direction of arrow D', the position T on the circumferential surface of the heat roll 13 changes.
When the paper 26 is pulled out, the portion to which the unfixed toner has adhered moves to position T'.

At this point, the heat roll 13 and the pressure roll 12 are in contact with each other, but no toner is attached to the circumferential surface of the heat roll 13 located at the contact portion between the heat roll 13 and the pressure roll 12. Therefore, the toner adhering to the circumferential surface of the heat roll 13 can be prevented from re-adhering to the pressure roll 12.

Further, when the fixing unit cover 14 is further rotated in the direction of 30°D' and the fixing unit cover 14 is completely closed, the position T' where the toner adheres on the circumferential surface of the heat roll 13 is
Move to T″ (β=α=40°).

On the other hand, when the fixing section cover 14 is closed as described above, the drive gear 21 also rotates in the direction B', but due to the action of the one-way bearing 21a, the rotational force is not transmitted to the drive shaft 21b, which may adversely affect the drive system. There isn't.

After removing the paper 26 that caused the paper jam as described above and closing the fixing unit cover 14, the fixing operation is restarted again to clear the thermal roll 13.
The adhering toner adhering to the T″ part is removed from the heat roll 13.
Cleaning felt 28 according to the rotation in the direction of arrow E.
Toner will not adhere to the next sheet of paper that is cleaned and sent to the fixing device 11.

Further, since toner does not adhere to the circumferential surface of the pressure roll 12, toner does not adhere to the back surface of the paper.

As described above, in this embodiment, the fixing section cover 14
By closing, the toner adhering to the circumferential surface of the heat roll 13 is prevented from re-adhering to the circumferential surface of the pressure roll 12. In addition, the fixing section cover 14
Cover gear 23 and fixing gear 2 that move when closing
Of course, the number of teeth in No. 2 is not limited to 38 or 28, and other numbers of teeth may be used.

[Effect of idea]

As explained in detail above, according to the present invention, even if, for example, a paper jam occurs in an image forming apparatus using the fixing device of the present invention, and toner adheres to the heat roll during the paper jam removal, the next Since adhering toner is cleaned before the paper enters the fixing device, toner does not adhere to the next paper and stain the paper.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the fixing device of this embodiment with the fixing section cover opened, FIG. 2 is a perspective view of the fixing device of this embodiment, and FIG. 3 is the fixing section cover of the fixing device of this embodiment. FIG. 4 is a configuration diagram explaining the gear drive of the fixing device of this embodiment, and FIG.
The figure is a sectional view of a conventional fixing device. 11... Fixing device, 12... Pressure roll, 13
... Heat roll, 14 ... Fixing section cover, 15a,
15b... Spring, 16a, 16b... Lever member, 18... Side plate, 21... Drive gear, 21a...
...One-way bearing, 21b... Drive shaft, 23...
Cover, 23a...Cover shaft, 23b...One-way bearing, 28...Cleaning felt.

Claims (1)

[Claims for Utility Model Registration] A first roller that has a built-in heat source and is in contact with the toner image side of the paper; a second roller that is in pressure contact with the first roller;
a cleaning member that cleans the surface of the first roller, and in which the first roller and the second roller are capable of coming into contact with each other, the first roller is moved to a predetermined position during a closing operation of a cover that covers the first roller. A fixing device characterized by being provided with a rotation mechanism for rotating an angle.