JPH079162Y2 - Pressing mechanism of image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a pressing mechanism of an image forming apparatus, and more specifically, a fixing side plate of a fixing device is pressed by an upper pressing means to obtain a predetermined pressure necessary for fixing. The present invention relates to a pressing mechanism of an image forming apparatus.

[Conventional technology]

Generally, in an image forming apparatus, for example, a copying machine, as shown in FIG. 1, a lower frame 1 below a copying paper conveyance path is provided.
Side and the upper frame 2 side above, the upper frame 2 is normally placed in a horizontal position, but when an accident such as a paper jam of the copying machine occurs, the upper frame 2 is placed. The body 2 is inclined upward with its pivotal shaft 3 serving as a fulcrum to release the pressure of the fixing side plate 7 of the fixing device 13 and release the pressure between the upper roller 4 and the lower roller 5, The jammed paper can be easily removed.

The fixing device 13 includes a fixing roller 6 including an upper roller 4 and a lower roller 5, and a fixing side plate 7 that supports the upper roller 4.
And a lower roller support plate 9 for supporting the lower roller 5 and a spring 11 as a drive source of pressure. The tension force of the spring 11 is adjusted by a screw 12.

The lower roller support plate 9 exerts a force to push the lower roller 5 to the upper roller 4 with the pivot shaft 10 serving as a fulcrum.

On the other hand, when the upper frame 2 is closed and pressed downward, the abutting part 2a at the lower end of the upper frame presses the abutting part 7a at the upper end of the fixing side plate 7, and the fixing side plate 7 fulcrums its pivot shaft 8. As a result, the upper roller 4 presses the lower roller 5, and a preset strong constant pressure, that is, a fixing pressure is generated between the upper and lower rollers 4 and 5.

This strong fixed fixing pressure is set to be equal to the pressure between the upper and lower rollers 4 and 5 when the upper frame 2 is pressed and closed.

When the upper frame 2 is pressed downward, the contact portion 2a at the lower end of the upper frame 2 contacts the contact portion 7a at the upper end of the fixing side plate 7, and the contact portion 7a is pressed.

A pressing force not only works between the two contact portions 2a and 7a, but also a force of rubbing against each other works.

Since the upper frame 2 rotates about its pivot 3 as a fulcrum, it has a radius of gyration L ₁ of the contact portion 2a, and the fixing side plate 7 is
Since the pivot shaft 8 rotates about the fulcrum, the contact portion 7a
Since it has a radius of gyration L ₂ , the size of L ₁ and L ₂ are different,
In addition, since the positions of the fulcrums are different, the functions of both contacting parts due to the pressing are different, and the rubbing is caused.

[Problems to be solved by the device]

The abutting portions having such a structure cannot rub the upper and lower rollers 4 and 5 at a certain pressure because the abutting portions are rubbed against each other while being pressed against each other, and are worn and damaged so that the abutting points are retracted. However, fixing failure will occur.

An object of the present invention is to prevent abrasion of the contact portions 2a and 7a between the upper frame body and the fixing side plate of the image forming apparatus and eliminate the occurrence of defective fixing.

[Means for Solving the Problems]

To achieve the above object, the present invention provides the following pressing mechanism for an image forming apparatus. That is, the present invention is directed to a fixing side plate having a turning radius that rotates about a pivot shaft attached to a lower frame and a pivot shaft at a position different from the pivot shaft of the fixing side plate on the lower frame. A pressing mechanism of an image forming apparatus, which is pivotally supported by an upper pressing means having a turning radius larger than a turning radius of the fixing side plate and pivoted up and down with the pivot as a fulcrum. Reinforcing parts are provided at the abutting portions of the upper pressing means and the fixing side plate in order to prevent abrasion of the portions where the upper pressing means and the fixing side plate contact each other when the means is pressed against the fixing side plate. This is a pressing mechanism of the image forming apparatus.

[Action]

In the above-mentioned structure, since the abutting portions of the upper pressing means and the fixing side plate are provided with the reinforcing portions respectively, abrasion damage is prevented and the initial fixing pressure applied by the upper pressing means is kept constant.

〔Example〕

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will now be described with reference to the drawings and how the structure of the present invention is embodied.

FIG. 1 shows an embodiment of the present invention, and a so-called shell type copying machine will be described as an example of the copying machine.

1 is a lower frame body 2 is an upper frame body which constitutes an upper pressing means, 3
Is a pivot shaft thereof, and the upper frame 2 is opened or closed upward with the pivot shaft 3 as a fulcrum.

Reference numeral 4 is an upper roller, 5 is a lower roller, and the upper and lower rollers 4 and 5 constitute a fixing roller 6.

7 is a fixing side plate that supports the upper roller 4, 8 is a pivot shaft thereof, and the fixing side plate 7 transmits a force acting vertically with this as a fulcrum.

Reference numeral 9 is a lower roller support plate, 10 is a pivot shaft thereof, and 11 is a spring, which is a driving source of fixing pressure.

The abutting portion 7a at the upper end of the fixing side plate 7 abuts on the abutting portion 2a at the lower end of the upper frame 2 and is normally in pressure contact with each other, but these operations are described in detail in the conventional example. Therefore, it is omitted here.

FIG. 2 is a perspective view showing each embodiment of the pressing mechanism of the present invention.

In FIG. 2 (A), the abutting portions 2a, 7a of the upper frame 2 and the fixing side plate 7 form a bent plate bent in an L shape, and the abutting portions are in contact with each other. I try to wear it.
That is, the abutting portion of the upper frame body 2 is bent to bend the abutting portions of the bent plate 2a and the fixing side plate to form the bent plate 7a to form the reinforcing portion 15,
Since the bent portion 2a and the bent plate 7a are in surface contact with each other, the pressure is dispersed and the contact portion is protected from damage.

In FIG. 2B, the lower end, which is the contact portion of the upper frame body 2, is fitted with a U-shaped hard synthetic resin reinforcing member 14, and the contact portion of the fixing side plate 7 is used. Since a certain upper end 7a is bent into an L-shape to form a bent plate to form the reinforcing portion 15, a friction reducing effect and a contact portion dispersing effect can be obtained.

In FIG. 2C, the lower end 2a which is the contact portion on the upper frame 2 side is bent into an L shape to form a bent plate, and the contact portion of the fixing side plate 7 is formed. Since a certain upper end 7a is fitted with a U-shaped hard synthetic resin reinforcing member 14 to form the reinforcing portion 15, the combination is the reverse of that shown in FIG. 2 (B). As in the case of (B), the effect is that the friction is reduced and the contact portion is dispersed.

In FIG. 2 (D), the lower end 2a, which is the abutting portion of the upper frame 2, and the upper end 7a of the fixing side plate are fitted with U-shaped hard synthetic resin reinforcing members 14, respectively. Since it is the reinforcing portion 15, it is not strongly damaged by pressure or abrasion.

In the image forming apparatus described above, the upper frame of the copying machine is applied as the upper pressing unit, but the present invention is not limited to this, and the upper pressing unit is separately provided in addition to the upper frame. But it is possible.

[Effect of device]

The present invention provides a reinforcing portion at the contact portion between the upper pressing unit and the fixing device to prevent pressure contact between both contact portions and wear of the contact portion due to friction, so that the strength of the fixing pressure is reduced to the initial value. There are advantages that it can be held for a long time from the time of setting, the pressing mechanism of the image forming apparatus normally functions, and fixing defects can be eliminated.

[Brief description of drawings]

FIG. 1 is a view showing an embodiment of the present invention, and FIGS. 2A to 2D are perspective views showing respective embodiments of a pressing mechanism of the present invention. 2 ... upper frame, 2a ... 2 contact part, 7 ... fixing side plate,
7a ... 7 contact part, 14 ... reinforcing member, 15 ... reinforcing part.

Claims (4)

[Scope of utility model registration request] 1. A fixing side plate having a turning radius which rotates about a pivot shaft attached to a lower frame, and a pivot at a position different from the pivot of the fixing side plate on the lower frame. A pressing mechanism of an image forming apparatus, which is pivotally supported by an upper pressing means having a turning radius larger than a turning radius of the fixing side plate and pivoted up and down with the pivot as a fulcrum. In order to prevent the wear of the portions where the upper pressing means and the fixing side plate contact each other when the means is pressed against the fixing side plate, a reinforcing portion is provided at each contact portion of the upper pressing means and the fixing side plate. A pressing mechanism for an image forming apparatus, characterized in that 2. The image forming apparatus according to claim 1, wherein the reinforcing portion is formed of a bent plate on both the upper pressing means side and the fixing side plate side. Pressing mechanism. 3. The utility model registration claim, wherein one of the upper pressing means and the fixing side plate side is fitted with a hard resin reinforcing member and the other is a bent plate. The pressing mechanism for an image forming apparatus according to item 1 above. 4. The image forming apparatus according to claim 1, wherein the reinforcing portion is fitted with a hard resin reinforcing member on both the upper pressing means side and the fixing side plate. Pressing mechanism.