JPH0478995B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device used in an image forming apparatus.

An explanation will be given below using an electrophotographic copying machine as an example.

[Prior Art and its Problems] As a fixing device for an electrophotographic copying machine, a roll fixing device is well known in which a copy paper is passed between a pair of rolls and a toner image on the copy paper is heated and fixed. As methods for separating the copy paper from the above-mentioned roll, there have been proposed methods such as a method of separating the copy paper by jetting air between the roll and the copy paper, a method of separating the copy paper by suction, or a method of separating the copy paper using a separating claw. has been done. However, among these methods, the method of separating using separation claws has the simplest structure and can reliably separate the copy paper from the roll. By the way, the above-mentioned fixing device is normally located just before the copy paper processed in the electrophotographic copying machine is discharged from the copying machine due to its configuration and usage. Therefore, in addition to paper jams caused by poor separation in the fixing device itself, paper jams in the fixing device can also occur due to troubles in the feeding, transfer, and conveyance paths of the copy paper, or problems with the copy paper. As described above, paper jams often occur in the fixing device, and therefore, the frequency of handling them is also high.

Here, an example of a conventional fixing device is shown in FIG. 1 and will be described.

In the figure, a heating roll 1 is placed on the copy paper conveyance exit side.
A guide 7 is conveyed in close proximity to the separation claw 4 which is in pressure contact with the separation claw 4 and which is rotatable around the fixed shaft 5, and the pressure contact roll 3.
is provided. 2 is an infrared heater that heats the heating roll 1. Furthermore, the separating claw 4 is required to have good heat resistance, abrasion resistance, and sliding properties, and generally, the tip of the claw is thin and sharp in order to separate the copy paper that is trying to adhere to the heating roll. It's summery. Note that 7, 8, and 9 are paper guides, and 10 is a discharge roll.

As described above, in the roller fixing device, although the separation claws for preventing paper jams have been well thought out, little consideration has been given to countermeasures when paper jams occur.

[Object of the Invention] Therefore, an object of the present invention is to provide a roll-type fixing device that facilitates handling of paper jams without deteriorating fixing performance.

[Summary of the Invention] The present invention, which achieves the above object, is an image forming apparatus having a pair of rollers that grips and conveys a sheet material and fixes a toner image thereon. The present invention is characterized in that by opening this cover, the conveyance path behind the roller pair is opened while the roller pair remains in pressure contact with each other.

[Embodiments of the present invention] Examples of the present invention will be described below with reference to FIGS. 2, 3, and 4.

FIG. 2 is a sectional view of a fixing device to which an embodiment of the present invention is applied.

In the figure, an infrared lamp 1 for heating inside
1 and a pressure roller 13, which presses against the roller 12 and forms a nip, rotate in the direction of the arrow to fix the toner image on the copy paper.
A separation claw 1 is provided on the copy paper delivery side of this heating roll 12.
A plurality of rollers 4 are rotatably disposed on a shaft 15 and pressed against the surface of the heating roll 12 by a spring 16. The copy paper separated from the roll by the separation claw 14 passes between the upper and lower conveyance sections 17 and 18, and is transferred to the tray 2.
It is stored in 4. The shaft 15 and the upper conveyance section 17 are fixed to a cover 19 which also serves as heat insulation, and the cover 1
9 is rotatable around a hinge 20.
In addition, in the figure, 18' is a guide.

Further, using FIG. 3, explanation will be given on handling paper jams.

First, when the handle 21 provided on the cover 19 is pulled in the direction of the arrow, the shaft 21 fixed on the cover 19
The handle 21 rotates around . Therefore, the handle 21 is released from the fixing dowel 23 on the fuser main body, and
The cover 19 is rotatable around the hinge 20.

Here, since the handle 21 is connected to the separation claw 14, the rotation of the handle 21 in the direction of the arrow causes the separation claw 14 to rotate around the shaft 15 and separate from the surface of the heating roll 12 as shown in FIG. Separate. Next cover 1
When the cover 19 is rotated around the hinge 20 and opened, the cover 19 supports the shaft 15 that supports the separation claw 14 and the upper conveyance section 17. Cover 19 in the center
Rotate and move with the In other words, as shown in FIG. 4, the separating claw 14 is in contact with the heating roll 12 at a position separated from the separating position where the copy paper is separated from the heating roll 12. This provides sufficient space for clearing paper jams by moving to a position away from the copy paper conveyance position opposite to the copy paper transport position. Therefore, not only is it easy to perform jamming, but also there is no risk of damaging the separating claws during the jamming operation since there are no separation claws in the jamming area.

Further, as described above, when opening the cover 19, the separating claws 14 are rotated around the shaft 15 to separate them from the surface of the heating roll 12, and then the separating claws 14 are moved away from the cover 19.
Since the copy paper is rotated around the hinge 20, the copy paper is separated between the heating roll 12 and the separating claw 1.
Even in a state where the paper is jammed and an excessive force is applied to the separation claw 14, it is easier to separate the paper than when the separation claw 14 is suddenly rotated around the hinge 20 and moved. The load on the claws 14 is reduced, and deformation and damage to the separation claws 14 can be further prevented.

Next, after the jamming process, the cover 19 is returned to its original position, and the handle 21 is rotated in the opposite direction to lock into the dowel 23. Here, when the cover 19 is closed, the separating claw 14 rotates around the hinge 20, and instead of suddenly returning to the position where it contacts the roll 12, it temporarily separates from the roll 12 as shown in FIG. It rotates around the hinge 20 and returns to the position, and then rotates around the shaft 15 in conjunction with the action of locking the handle 21 to the dowel 23 and moves the roll 12
, the separation claw 14 rotates vigorously around the hinge 20 and collides with the roll 12, causing damage.
It can prevent deformation.

In the embodiment described above, the separation claw displacement means rotates the separation claw 14 about the shaft 15 in connection with the opening/closing operation of the cover 19 to contact and separate the separation claw from the heating roll 12. Although this is done in conjunction with the locking mechanism of the cover, it may also be done in conjunction with the opening/closing operation of the cover using a link mechanism, solenoid, or the like.

In the above-mentioned embodiment, as is clear from the drawings, the transport path is opened by opening the cover 19, but this cover does not take part in the pressure contact between the roller pair, and when the cover is opened, the roller pair does not come into pressure contact. It remains retained.

In a roller pair type fixing device, the pressure contact state of the roller pair has a large effect on fixing performance.

Therefore, in the present invention, even when the cover is opened, the pair of rollers remains in pressure contact with each other, so that the state of pressure contact does not change and the fixing performance is not deteriorated.

[Effects of the Invention] As can be seen from the above description, according to the present invention, the operability of jam processing can be improved without deteriorating the fixing performance in a roller pair type fixing device.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional fixing device, and FIGS. 2, 3, and 4 are sectional views of a fixing device according to an embodiment of the present invention. In the figure, 1, 12... heating roll, 2, 1
1... Infrared heater, 3, 13... Pressure roll,
4, 14... Separation claw, 5, 15... Fixed shaft, 6,
16...Spring.

Claims (1)

[Scope of Claims] 1. An image forming apparatus having a pair of rollers for gripping and conveying a sheet material and fixing a toner image, comprising: an openable cover that forms an outer wall of the apparatus main body; and the cover is opened. An image forming apparatus characterized in that a conveyance path behind the roller pair is opened while the roller pair is kept in pressure contact with each other.