JPH07295429A - Image forming device - Google Patents

Abstract

PURPOSE:To facilitate the roller pressure adjustment and the like of a fixing part in an image forming device of such a constitution that transfer material carrying a toner image is conveyed along a guide plate to reach between a fixing roller and a pressure roller to fix the toner image. CONSTITUTION:An operating part for adjusting the transfer material approach angle of a guide plate to a fixing roller 1, adjusting (17) the pressure contact force of a pressure roller 2 to the fixing roller 1 and releasing the pressure contact of the pressure roller 2 with the fixing roller 1 is provided on the opening/closing door side of the image forming device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine and a printer, and more particularly to an image forming apparatus including a roller type fixing device including a fixing roller and a pressure roller.

[0002]

2. Description of the Related Art As a fixing device in an image forming apparatus,
A so-called roller-type fixing device is known in which a transfer material carrying an unfixed toner image is passed between a fixing roller and a pressure roller pressed against the fixing roller to fix the toner image. Such a device has an advantage that the structure is simple and the heating temperature is relatively low and it is easy to control as compared with a fixing device having another structure such as an oven type.
There are problems such as wrinkling of the transfer material and transfer omission. In addition, when the apparatus is shipped with the pressure roller kept in pressure contact with the fixing roller at the time of shipment, the appropriately adjusted pressure contact force may change or may have an unfavorable effect.

For this reason, means for adjusting the advancing angle of the transfer material into the fixing roller, which may cause wrinkles, means for adjusting the pressure contact force of the pressure roller against the fixing roller, and pressure against the fixing roller. The above problem is dealt with by providing a means for releasing the pressure contact force of the roller.

[0004]

By the way, the operation portion of such means is conventionally located near the portion to be adjusted, for example, near the guide plate of the transfer material or near the pressure roller. To make adjustments,
For example, the fixing device unit must be pulled out from the main body of the image forming apparatus, and the maintenance is not sufficiently simplified.

The present invention has been made in such a situation, and an object thereof is to provide a fixing device capable of adjusting the pressure contact force of a pressure roller to a fixing roller of a guide plate with a simple and convenient structure. To do.

[0006]

In order to solve such a problem, the present invention conveys a transfer material carrying a toner image along a guide plate between a fixing roller and a pressure roller to fix the toner image. In the image forming apparatus, an operation part for adjusting the transfer material entrance angle of the guide plate with respect to the fixing roller, adjusting the pressure contact force of the pressure roller with respect to the fixing roller, and releasing the pressure contact of the pressure roller with respect to the fixing roller is provided as an opening / closing door of the image forming apparatus. It is characterized in that it is provided on the side.

[0007]

With such means, the adjustment of the transfer material advancing angle of the guide plate, the adjustment of the pressure contact force of the pressure roller, and the release of the pressure contact force of the pressure roller are extremely simple in that the operating portion is exposed by opening the opening / closing door. It can be done on one side (opening / closing door side) with only simple work. Therefore, for example,
It is possible to make delicate adjustments of the approach angle of the guide plate and the pressure contact force of the pressure roller from the same direction.

[0008]

The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus to which the present invention can be applied, and is roughly divided into an image forming section 100, a transfer material feeding section 200, a document scanning section 300, and a fixing section 400.

The image forming section 100 includes a photosensitive drum 101, a corona charger 102 arranged around the photosensitive drum 101, and an optical device 1.
03, a developing device 104, a transfer / peeling device 105, and a cleaning device 106, which operate according to a well-known xerographic process to form a copy image of a document conveyed by the document scanning unit 300.

In this example, the transfer material feeding section 200 is loaded with two roll papers 201 and 202 of different sizes, and a roll paper of any one selected size is drawn out and cut into a predetermined size by a cutter 203. It is cut and conveyed to the image forming unit 100.

The transfer material on which the toner image formed by the image forming unit 100 is transferred is sent to the fixing device 400 by the conveyor belt 107, the toner image is heat-fixed there, and the discharge roller 401 discharges the discharge port 402. Is discharged from the aircraft. The fixing device 400 is a main part of the present invention, and the fixing device will be described below.

As shown in the upper right of FIG. 1, the fixing device 400
Is basically a fixing roller 1, a pressure roller 2 that is pressed against the fixing roller 1, a fixing roller 1 and a pressure roller 2.
A guide plate 3 for guiding the transfer material is provided in a nip between the guide plate 3 and. These members are integrated together with related devices such as a release agent applying device, a peeling claw, a cleaner, and a temperature detector arranged around the fixing roller 1 to form a fixing device unit. It can be pulled out from the main body of the image forming apparatus.

The fixing roller 1 has a heater inside, and heating is controlled so that the surface of the fixing roller 1 reaches a predetermined fixing temperature. As is well known, the surface of the fixing roller 1 is coated with a releasing agent for toner such as Teflon. A pressure roller 2 is arranged below the fixing roller 1 in contact therewith, and a transfer material carrying an unfixed toner image is carried between the rollers along the upper surface of the guide plate 3 and passes between the rollers. When this is done, the toner image is fixed.

The pressure roller 2 is a roller made of an elastic material such as silicon rubber, and its both ends are rotatably supported by a pair of left and right support plates 4 (FIGS. 2 and 3). Each support plate 4 is pivotally provided on a side plate 7 of the fixing device by a pivot 6 provided on the transfer material entrance side, that is, on the inner side of the main body of the apparatus, whereby the pressure roller 2 is centered on the pivot shaft 6. Further, the fixing roller 1 can be moved in the direction of coming into contact with and separating from the fixing roller 1.

In order to adjustably press the pressure roller 2 against the fixing roller 1, an L-shaped adjusting member 8 is provided for both supporting plates 4. Although the following configurations are provided on both the left and right sides of the pressure roller 2, only one side will be described for convenience. The adjusting member 8 is provided so as to be pivotable with respect to a shaft 9 fixed to the side plate 7 of the fixing device. A pin 11 is projectingly provided on the upper side of the adjusting member 8 and bent downward in a direction perpendicular to the paper surface of the lower side. It has a flange 12.
The pin 11 on the upper side has a shaft 13 whose one end projects from the support plate 4.
The other end of the adjustment spring (tensile spring) 14 hung on the support plate 4 is hung on the support plate 4 by pulling the adjustment spring.
Is lifted upward about the pivot 6, that is, in the direction in which it is pressed against the fixing roller 1. On the other hand, the tip of the adjusting screw 17 screwed into the fixing portion 16 of the fixing device is positioned in contact with the back surface of the flange 12 on the lower side of the adjusting member 8. Although not shown, the adjusting screw 17 is appropriately provided with a set screw for preventing the screw from loosening.

In such a structure, the adjusting spring 17 is turned and the degree of screwing is changed to adjust the adjusting spring 1.
It is possible to adjust the distance between the end portions (action point distance) of 4 to adjust the spring pressure, and thus the pressure contact force of the pressure roller to the fixing roller 1, to an optimum value. The tooth profile portion 50 formed on the rear end projecting portion (right end in the figure) of the support plate 4 serves as a measure of the pressure contact force, and has a tooth profile of the same shape arranged in parallel with this projecting portion. Match the tooth profile of the member with the tooth step,
Alternatively, an appropriate straight rod is pressed against the tooth portion such as shifting the tooth step by one step, and the adjusting screw 17 is operated as a measure of the pressure contact force.

On the other hand, a pressure contact releasing means 20 is provided to release the pressure contact force of the pressure roller 2 against the fixing roller 1 at the time of shipping and transportation. 2 shows the state in which the releasing means 20 is in operation when the releasing means 20 is not operating. The releasing means 20 includes a latch lever 21 whose upper end is pivotally supported by the pivot 9 of the adjusting member 8 and a connecting lever 22 whose lower end is pivotally supported by the shaft 13 of the support plate 4. . A pin 23 projecting from the upper end of the connecting lever 22 projects into an elongated hole 24 formed substantially in the center of the latch lever 21. The latch lever 21 and the connecting lever 22 have flanges 21a and 22a, respectively, on their back surfaces, which are bent in a direction perpendicular to the plane of the drawing.
In addition, the lower end of the latch lever 21 has an inclined portion 25 and a concave portion 26 that follows the inclined portion 25, as particularly shown in FIG.

In such a structure, when the pressure contact force of the pressure roller 2 is released from the operating state shown in FIG. 2, the back surface 21a of the latch lever 21 is pushed to the left as viewed in the figure. Thereby, the slanted portion 25 at the lower end of the latch lever 21
Is brought into contact with the shaft 13 of the support plate 4 and moves while pushing it down, then the recess 25 is dropped into the shaft 13 (FIG. 3), and the pressure roller 2 is maintained in a state of being separated (or weakened its pressure contact force) from the fixing roller. To do. In the illustrated example, the pressure roller 2 and the fixing roller 1 are set to be in contact with each other with almost no load in this released state, but the present invention is not limited to this.

FIG. 4 further shows a mechanism for adjusting the transfer material advancing angle of the guide plate 3 for guiding the transfer material to the fixing roller 1. As shown in the figure, both sides of the guide plate 3 are fixed to the upper sides of a pair of L-shaped support plates 32 (only one of which is shown in the figure) arranged so as to be pivotable about a shaft 30. The pivot angle of the transfer material with respect to the fixing roller 1 is adjusted as indicated by the chain line in the figure. The lower end of the support plate 32 is connected to a pin 34 protruding from a connecting bar 33 that is guided so as to be movable in the left-right direction in the figure, and is configured to pivot according to the movement of the connecting bar 33. There is. At the right end of the connecting lever 33, there is a bent portion 36 in a direction perpendicular to the plane of the drawing, and with respect to this portion 36, an adjusting screw provided on a fixed portion 37 of the fixing device so as to be rotatable but not axially movable. 38 is provided by screwing. By rotating the adjusting screw 38 left and right, the connecting lever 33 is rotated.
Can be moved to the left and right to adjust the transfer material entrance angle of the support plate 32, and thus the guide plate 3.

The operating parts of the adjusting means and the releasing means described above, that is, the adjusting screw 17 for adjusting the pressure contact force of the pressure roller 2, the releasing lever (latch lever) 21, and the adjusting screw 38 of the guide plate 3 are all images. It is located on the side of the opening / closing door of the forming apparatus, and the operator can easily perform the above adjustment by simply opening the opening / closing door. In this example, referring again to FIG. 1, the opening / closing door is a unit 61 including a discharge roller 401, and the unit 6 is centered around the shaft 60.
1 is pivoted in the clockwise direction as viewed in the drawing to open it, so that the operation portions of the adjusting means and the releasing means described above are operably exposed. Reference numeral 63 in the drawing is a clamp for locking the unit "61.

[0014]

As described above, according to the present invention, the necessary adjustment in the fixing device portion by opening the opening / closing door can be appropriately and easily performed by operating the adjusting screw or the like.

[Brief description of drawings]

FIG. 1 is a schematic side view showing an example of an image forming apparatus according to the present invention.

FIG. 2 is a diagram showing a fixing device of the apparatus of FIG.

FIG. 3 is a diagram showing another state of the apparatus of FIG.

FIG. 4 is a view showing an adjusting means of a guide plate for guiding a transfer material to a fixing device.

[Explanation of symbols]

 1 Fixing Roller 2 Pressure Roller 3 Guide Plate 17 Adjusting Screw 21 Latch Lever 38 Adjusting Screw

Claims (1)

[Claims] 1. An image forming apparatus for fixing a toner image by conveying a transfer material carrying a toner image between a fixing roller and a pressure roller along a guide plate, and entering the transfer material of the guide plate into the fixing roller. An image forming apparatus comprising: an operation unit for adjusting an angle, adjusting a pressure contact force of a pressure roller to a fixing roller, and releasing pressure contact of the pressure roller to a fixing roller, which is provided on an opening / closing door side of the image forming apparatus.