JPH0241640Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a pressure fixing device that fixes toner on a toner support by passing the toner support with a toner image between rolls pressed together. It can be used in electrophotographic printers, copying machines, etc.

[Conventional technology]

A conventional pressure fixing device consists of a fixing roll at the top and a back-up roll at the bottom.
There is a method in which the toner support is held and fed by a pair of rolls, but since both rolls are rigid, it is difficult to apply uniform pressure over the entire length of the rolls.

Therefore, it has been considered to solve the above problem by using an elastic roll as one of the lower back-up rolls, but in this case, there was a problem that the elastic roll deteriorates over time.

To deal with this, two of the three rigid rolls
The books are placed parallel to each other, and one roll is placed so as to intersect with a pair of rolls that are parallel to each other at a small angle. There was a problem in that the width of the toner support with which good fixing properties could be obtained was limited.

Next, as a technique for dealing with these problems, Japanese Patent Application Laid-Open No. 57-200073 by the present applicant will be explained based on the drawings.

FIG. 4 is a side sectional view of the pressure fixing device,
A pair of rolls, a fixing roll 1 and a counter roll 2, are provided, and a sliding member 3 is provided which contacts the pair of rolls above and below, and a pressure bar 4 is provided on the fixing roll 1.
A plurality of load means 5 which are slidable in the axial direction of the roll are arranged on the pressure bar 4 and housed in a frame 6. At least one of the plurality of load means 5 is slid away from the pressure bar 4.

As a result, the plurality of loading means 5 on the pressure bar 4 are moved to necessary positions in accordance with the various widths of the toner support 7 passing between the fixing roll 1 and the opposing roll 2, and the fixing roll 1 is moved to the required position. Since it can be pressurized,
It is possible to change the load distribution on the toner support 7, and the load means 5 can be attached to the pressure bar 4 as needed.
The total load distribution can also be changed by separating the Therefore, the pressure fixing device can accommodate various widths of the toner support 7.

[Problem that the invention attempts to solve]

However, in the above-mentioned Japanese Patent Application Laid-Open No. 57-200073, when a large number of sheets are fixed, the toner is offset to the fixing roll 1 that presses the toner supporting surface side of the toner support, and the toner comes into contact with the fixing roll 1. Problems arise in that they adhere to the sliding material 3, increasing the coefficient of friction between the fixing roll 1 and the sliding material 3, and increasing the torque required to rotate the fixing roll 1.
For this reason, there was a problem that the replacement cycle of the sliding material 3 was also shortened.

[Means for solving problems]

To address the above-mentioned problems, the present invention provides a back-up bar that conveys the toner support under pressure with a fixing roll and a back-up roll that is in pressure contact with the fixing roll, and presses the back-up roll through a sliding material. The backup bar is provided with a plurality of pressure means movable in the axial direction of the roll.

The fixing roll has a rigidity that does not impair fixing performance due to deflection between loads applied by the pressure means, and the sum of the rigidities of the back-up roll and the back-up bar also satisfies the above-mentioned conditions. It's getting old.

[Effect]

According to the above means, the pressure means is moved in the axial direction of the back-up roll to sequentially change the pressure points, and the pressure of the pressure means fixes the back-up roll through the back-up bar and the sliding material. The toner support is conveyed under pressure by a back-up roll and a fixing roll, and the toner on the surface of the toner support is fixed onto the toner support under pressure.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1, which is a front view of the embodiment, and FIG. 2, which is a side sectional view thereof.

1 and 2, 8 is a fixing roll, 9 is a back-up roll that is in pressure contact with the fixing roll 8, 10 is a frame, and 11 is a ball bearing that rotatably supports the fixing roll 8. are fixed to both sides of the frame 10. Reference numeral 12 denotes needle bearings that rotatably support the back-up roll 9. The needle bearings 12 are arranged on both sides of the frame 10 and can be slightly slid in the vertical direction, and their outer rings are regulated by the frame 10. and cannot be rotated. Reference numeral 13 indicates a back-up bar disposed oppositely below the back-up roll 9; 14 indicates a sliding member provided on the back-up bar 13;
4 comes into contact with the backup roll 9. 15
16 is a coil spring compressed and stored in the spring carriers 15a, 15b; 17 is two rollers provided above the spring carriers 15a, 15b; 1
8 is two rollers provided below, and 19 is a guide shaft that supports the movement of the spring carriers 15a, 15b. Spring carrier 15a,
15b moves the roller 17 to the backup bar 1.
3 and the roller 18 is in contact with the guide shaft 19. Therefore, the spring carrier 15
a and 15b are movable in the axial direction of the fixing roll 8 and the backup roll 9. 20a, 2
0b is a synchro belt supporting the spring carriers 15a and 15b, 21 is a synchro belt pulley for supporting the drive of the synchro belts 20a and 20b, and 22 is a pressure force that presses the back up bar 13 without moving at one end of the back up bar 13. A spring device as a pressure means, 23 is a spring thereof, 24 is a gear provided on the fixing roll 8, 2
5 is a gear installed in Backup Prowl 9,
Both gears 24 and 25 are in mesh with each other. Furthermore, 26 is a gear provided on the synchronized belt pulley 21, and the gear 26 is rotated by a reversible motor or the like (not shown). 27 is a toner support that passes between the fixing roll 8 and the back-up roll 9; 28 is the toner offset on the fixing roll 8; 29 is a scraper for scraping off the toner 28; 30 is silicone oil or the like to prevent the toner 28 from being offset. The felt is impregnated with a release agent and is pressed against the fixing roll 8.

Next, the operation of the pressure fixing device having the above configuration will be explained.

First, the spring carriers 15a and 15b are moved to required points according to the various widths of the toner support 27. At this time, the spring carrier 15b can be separated from the backup bar 13 and moved onto the frame 10 if necessary. By the above operation, the pressure point is set according to the width of the toner support 27, and the spring device 22, the spring carrier 15a, and if necessary the spring carrier 15b presses the back up bar 13, and the back up bar 13 is pressed against the sliding member. The backup roll 9 is pressed against the fixing roll 8 via the roller 14.

The toner support 27 is conveyed under pressure between the fixing roll 8 and the backup roll 9. At this time, the toner is fixed on the toner support 27 and a part of the toner 28 is fixed on the fixing roll 8.
offset to the surface of This toner 28 is scraped off from the surface of the fixing roll 8 by a scraper 29, and then a release agent is applied to the surface of the fixing roll 8 by a felt 30 to prevent toner offset. In the above-described embodiment, the spring device 22 is fixed because the reference position of the conveyance system is set at the right end in FIG. 1, and there is no need to move the pressurizing means located nearby. When the fixing roll 8 receives pressure from the back-up roll 9, it needs to have a rigidity that does not impair fixing performance due to deflection between loads. For the same reason, the sum of the rigidities of the backup roll 9 and the backup bar 13 must also satisfy this condition. The required rigidity here can be reduced by dividing the load, compared to the conventional method in which the entire load is applied to both ends of the roll. Further, as described above, the spring carriers 15a and 15b are configured to move and change the pressure point and total load to correspond to various widths of the toner support 27, which will be explained next.

FIG. 3 is a diagram showing the pressure point positions for various toner supports 27, where _X1 is the position of the spring device 22, and _X2 is the position of the spring carrier 15a.
position, X ₃ is the position of spring carrier 15b,
F indicates the position of the frame 10, and W indicates the width of the backup bar 13. A indicates the widest toner support, and B, C, and D indicate narrow toner supports that gradually become narrower.

As shown in FIG. 3, for a wide toner support A, the pressure points X ₁ , X ₂ ,
Set to X ₃ position. On the other hand, for narrow toner supports B, C, and D, the spring carrier 1
5b is positioned on the frame 10 and separated from the backup bar 13, and the backup bar 13 is set at positions X ₂ and X ₁ so that the two pressurizing points of the spring carrier 15a and the spring device 22 are located. In this case, the narrow toner support B,
The position of X ₂ is gradually brought closer to X ₁ so as to correspond to the widths of C and D. The total load applied to the fixing roll 8 at this time is smaller than that in the case of the wide toner support 27 by the amount of force generated by the coil spring 16 of the spring carrier 15b that has moved to the frame 10.

As an example of the above embodiment, the fixing roll 8 has a diameter of 60 mm.
mm, and the back-up roll 9 is φ20 mm. After surface carburization and quenching to hardness H _RC : 60, hard chrome plated steel rolls are used, and the sliding material 14 that presses the back-up roll 9 is a Teflon-based member. was used. Then, each of the three pressure points is
It uses a compression coil spring that provides a restoring force of 240Kg.

In the pressure fixing device of this example described above, by changing the pressure point and the total weight, it was possible to obtain good fixing performance on various toner supports ranging from B4 width to B5 length. .

Further, by reducing the diameter of the back-up roll 9 to the necessary minimum, it is possible to reduce the frictional load torque caused by the sliding member 14, and at the same time, it is possible to promote downsizing of the device.

[Effect of idea]

As explained in detail above, in the present invention, no sliding material is used for the fixing roll, and the sliding material is only on the back-up roll side. Problems such as an increase in the coefficient of friction due to toner adhesion to the sliding material on the side, an increase in the rotational torque of the fixing roll, and an increase in the replacement cycle of the sliding material can be solved. Therefore, the torque required to drive the fixing roll does not increase, and the maintenance cycle of the apparatus can be significantly extended.

[Brief explanation of the drawing]

FIG. 1 is a front view of a pressure fixing device showing an embodiment of the present invention, FIG. 2 is a side sectional view thereof, FIG. 3 is a view showing pressure point positions for various toner supports, and FIG. FIG. 2 is a side sectional view of a pressure fixing device as a conventional example. 8... Fixing roll, 9... Backup roll, 10... Frame, 13... Backup bar, 14... Sliding material, 15a, 15b... Spring carrier, 22... Spring device.

Claims (1)

[Scope of utility model registration request] In a pressure fixing device that fixes a toner image by pressurizing and transporting a toner support between a pair of parallel rolls that are in pressure contact with each other, a sliding member is attached to one of the rolls located on the back surface of the toner support. A pressing member is provided which contacts the pressing member, and a plurality of pressing means for pressing the pressing member and applying a load are provided movably in the axial direction of the roll, and the pressing point is moved in accordance with the width of the toner support. A pressure fixing device characterized by: