JP3526324B2 - Image forming device - Google Patents

Description

Description: 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 a heat roller type fixing device including a fixing roller and a pressure roller. The present invention relates to an image forming apparatus. 2. Description of the Related Art As a fixing device in an image forming apparatus,
There is known a so-called heat roller type fixing device 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, thereby fixing the toner image. Such a device has the advantage that the structure is simple and the heating temperature is relatively low, and the control is easy, as compared with a fixing device having another configuration such as an oven type. It has problems such as transfer omission.
In addition, when the apparatus is shipped with the pressure roller pressed against the fixing roller at the time of shipment, the appropriately adjusted pressing force may change or have an undesirable effect. For this reason, wrinkles can be generated.
Means for adjusting the pressure contact force of the pressure roller with respect to the fixing roller and means for releasing the pressure contact force of the pressure roller with respect to the fixing roller are provided to address the above problem. [0004] By the way, the operating part of such means is conventionally located in the vicinity of the part to be adjusted, for example, in the place directly adjacent to the member such as in the vicinity of the pressure roller, Therefore, to make these adjustments,
For example, maintenance has not been sufficiently simplified, for example, the fixing device unit must be pulled out of the image forming apparatus main body. The present invention has been made in such a situation, and an object of the present invention is to provide a fixing device capable of adjusting and releasing a pressure contact force of a pressure roller with respect to a fixing roller with a simple and convenient configuration. . In order to solve the above-mentioned problems, the present invention conveys a transfer material carrying a toner image along a guide plate between a fixing roller and a pressure roller to form a toner image. In the image forming apparatus performing the fixing of the image forming apparatus, an operation unit that adjusts the pressure contact force of the pressure roller with respect to the fixing roller and releases the pressure contact of the pressure roller with respect to the fixing roller is provided on the opening and closing door side of the image forming apparatus. It is characterized by having a link mechanism for releasing the pressure contact of the pressure roller, and spring means having a dead point set so as to maintain the link mechanism in the released state. [0007] In order to solve the above-mentioned problems, the present invention conveys a transfer material carrying a toner image along a guide plate between a fixing roller and a pressure roller, and transfers the transfer material. In an image forming apparatus for fixing a toner image on a material, the image forming apparatus includes an adjusting unit that adjusts a pressure contact force of a pressure roller with respect to the fixing roller, and a release unit that releases pressure contact of the pressure roller with the fixing roller. The adjusting means includes an adjusting spring that acts to press the pressure roller against the fixing roller, an adjusting member that adjusts a distance between the ends of the adjusting spring (an operating point distance), and an adjustment that adjusts the position of the adjusting member. A screw mechanism, and the release unit has a link mechanism for releasing the pressure roller from being pressed against the fixing roller, and an operation unit that operates the link mechanism, and the operation unit is configured to open and close the image forming apparatus. When the link mechanism is operated to release the pressure contact of the pressure roller by the operation of the operation unit, the operation position of the link mechanism is set to the dead of the adjustment spring. The adjustment spring, the adjustment member, and the link mechanism are provided so as to be a point (dead point). Next, a preferred embodiment of the present invention will 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. The image forming apparatus roughly includes an image forming unit 100, a transfer material feeding unit 200, a document scanning unit 300, and a fixing unit 400. The image forming unit 100 includes a photosensitive drum 101, a corona charger 102 disposed 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. These devices operate according to a well-known xerographic process, and 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 selected size is pulled out and is cut into a predetermined size by a cutter 203. The sheet is cut and transported to the image forming unit 100. The transfer material onto which the toner image formed by the image forming unit 100 has been transferred is sent to a fixing device 400 by a conveyor belt 107, where the toner image is heated and fixed, and a discharge roller pair 401 discharges the toner image. It is discharged out of the machine from 402. 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.
Are basically a fixing roller 1, a pressure roller 2 pressed against the fixing roller 1, a fixing roller 1 and a pressure roller 2
And a guide plate 3 for guiding the transfer material to the nip between the two. These members are integrated with related devices such as a release agent application device, a peeling claw, a cleaner, and a temperature detector disposed around the fixing roller 1 to constitute a fixing device unit. It can be withdrawn from the forming apparatus body. The fixing roller 1 has a heater 1a inside, and is heated and controlled so that the surface thereof has a predetermined fixing temperature. As is well known, the surface of the fixing roller 1 is coated with a toner such as Teflon so as to be releasable. A pressure roller 2 is disposed below and in contact with the fixing roller 1, and a transfer material carrying an unfixed toner image guided along the upper surface of the guide plate 3 is inserted between the rollers 1 and 2. The toner image is fixed when passing between the rollers. The pressure roller 2 is a roller made of an elastic material such as silicon rubber, and both ends thereof are rotatably supported by a pair of left and right support plates 4 (FIGS. 2 and 3) of the fixing device. Each support plate 4 is supported around a shaft by a pivot 6 provided on the side where the transfer material enters, that is, provided inside the apparatus main body, and is provided so as to be pivotable with respect to a side plate 7 of the fixing device. As a result, the pressure roller 2 can be moved about the pivot 6 in a direction in which the pressure roller 2 comes into contact with or separates from the fixing roller 1. In order to enable the pressure roller 2 to adjust the pressure contact with the fixing roller 1, an L-shaped adjusting member 8 bent downward is provided at an upper position opposite to the pivot 6 of both support plates 4. Is provided. The following configuration is provided on each of the left and right sides of the pressure roller 2, but for convenience of description,
Only one side will be described. 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 protrudes from an upper end of the adjusting member 8, and a paper surface is provided on a lower side. It has a flange 12 bent in the vertical direction. A pin 11 on the upper side and a shaft 13 projecting from the support plate 4 at a position below the pin 11
An adjustment spring (tension spring) 14 is hung between the support plate 4 and the support plate 4.
At the center, that is, in the direction of pressing against the fixing roller 1. On the other hand, on the rear side (right side in the drawing) of the flange 12 on the lower side of the adjusting member 8, an adjusting screw 17 screwed to the fixing portion 16 of the fixing device is provided. Adjustment screw 17
Is screwed into the flange 12, and the angular position of the adjusting member 8 is adjusted by the screwing depth. Adjustment screw 1
7 is appropriately provided with a screwing 18. By turning the adjusting screw 17 in such a configuration and changing the degree of screwing, the adjusting member 8 is adjusted.
Is adjusted, thereby adjusting the distance between the ends of the adjusting spring 14 (the distance of the action point), and adjusting the spring pressure, that is, the pressure contact force of the pressure roller against the fixing roller 1 to an optimum value. The tooth-shaped portion 50 formed at the rear end protruding portion (right end in the drawing) of the support plate 4 serves as a measure of the pressing force, and is fixed in parallel with the protruding portion and having the same tooth shape. The adjustment screw 17 is operated as a guide of the pressing force by pressing an appropriate straight rod against the tooth portion, for example, by matching the tooth profile of the member with the tooth step or shifting the tooth step by one step. On the other hand, in order to release the pressure contact force of the pressure roller 2 with respect to the fixing roller 1 at the time of shipping or the like, a pressure releasing means 20 is provided. 2 shows a state in which the release means 20 is operated, and FIG. 3 shows a state in which the release means is not operated. The release means 20 includes a support lever 21 whose upper end is pivotally supported by the pivot 9 of the adjustment member 8 and a connection lever 22 whose lower end is pivotally supported by the shaft 13 of the support plate 4.
Is constituted. . A connection shaft 23 projecting from the upper end of the connection lever 22 is connected to the support lever 21 at substantially the center of the support lever 21. The support lever 21 and the connection lever 22 have flanges 21a and 22a on the back surface thereof, respectively, which are bent in a direction perpendicular to the plane of the drawing. In such a configuration, when the pressing force of the pressure roller 2 is released from the operation position shown in FIG. 3, the back surface 21a of the support lever 21 is pushed to the left as viewed in the figure.
Thereby, the connecting lever 22 is connected to the shaft 13 via the connecting shaft 23.
While pressing down (FIG. 2). The two flanges 21a, 22a are positioned so as to overlap in parallel. In this parallel state,
The pressure roller 2 is located at a position distant from the fixing roller 1, or is set to be in a state where there is almost no load on the fixing roller 1. Note that in the position of FIG. 2, the adjusting spring (tension spring) 14
1 and the connecting lever 22 so as not to pivot them in any direction, that is, to be located at a so-called dead point. Therefore, the distance in the x-axis direction (horizontal direction) from the pin 11 of the adjusting member 8 supporting the end of the adjusting spring to the base 9 thereof, and the connecting lever 22
The distance in the x-axis direction from the shaft 13 to the connection shaft 23 is optimally set to be the shortest. The operating portions 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 and the releasing lever (support lever) 21 are all located on the open / close door side of the image forming apparatus. Therefore, the operator can easily perform the above adjustment simply by opening the door. In this example, referring to FIG. 1 again, the opening / closing door is a unit 61 including a discharge roller 401,
The operation unit of the adjusting means and the releasing means is configured to be operably exposed by pivotally opening the unit 61 clockwise as viewed in FIG. Reference numeral 63 in the figure denotes a clamp for locking the unit 61. As described above, according to the present invention, the necessary adjustment in the fixing device by opening the opening / closing door can be appropriately and simply performed by operating the adjusting screw or the like.

BRIEF DESCRIPTION OF THE 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 shown in FIG. FIG. 3 shows another state of the apparatus of FIG. 2; [Description of Signs] 1 Fixing roller 2 Pressure roller 3 Guide plate 17 Adjusting screw 21 Support lever 38 Adjusting screw

Claims (1)

(57) [Claim 1] A transfer material carrying a toner image is conveyed between a fixing roller and a pressure roller along a guide plate, and the transfer material is
An image forming apparatus for fixing a toner image on, adjusted to adjust the pressure contact force of the pressure roller with respect to the <br/> fixing roller
And settling means, the pressure of the pressure roller against the fixing roller
Releasing means for releasing, wherein the adjusting means includes
An adjustment that acts to press the roller against the fuser roller.
Adjust the adjusting spring and the distance between the ends of the adjusting spring (operating point distance).
Adjusting member for adjusting the position of the adjusting member and adjusting screw for adjusting the position of the adjusting member
And the release unit is configured to fix the fixing of the pressure roller.
Link mechanism for releasing pressure contact with roller, and link mechanism
And an operation unit for operating the image forming apparatus.
It is located on the side of the opening and closing door, and is used for operation of the operation unit.
By operating the link mechanism, the pressure roller
When the pressure contact is released, the operating position of the link mechanism is
Before the dead point of the adjustment spring
An image forming apparatus provided with an adjusting spring, an adjusting member, and a link mechanism .