JPH0547253Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Technical Field> This invention relates to an opening/closing mechanism that is used in an image forming apparatus configured to be divided into upper and lower units and applies a force in the opening direction to the upper and lower units.

<Prior Art and Its Disadvantages> In an image forming apparatus that requires maintenance of built-in parts, the main body is divided into upper and lower halves, and the upper unit can be opened and closed with respect to the lower unit. Such an image forming apparatus includes an opening/closing mechanism that applies a force in the opening direction to the upper unit in order to facilitate opening/closing operations. This opening/closing mechanism is provided with points of action at both ends in the axial direction of the opening/closing operation in order to prevent the upper unit from shifting its position during the opening/closing operation. Conventionally, for the purpose of simplifying the structure and reducing costs, there has been a mechanism in which the opening/closing mechanism is equipped with a torsion bar having two elastic members to apply a force in the opening direction to both ends of the upper unit.

Normally, in many image forming apparatuses, the weight distribution of the upper unit is not uniform due to the arrangement of parts, and generally the two elastic members constituting a conventional torsion bar have the same elastic force.
The same force acts on both ends of the upper unit, and a torsional force acts on both ends, resulting in uncertain opening/closing operations and early deterioration. In order to prevent this, it is necessary to strengthen the rigidity of the upper unit, which has the disadvantage of increasing costs.

In addition, in the case where one compression spring is provided at each end in the axial direction for opening/closing operation, two compression springs with different elastic forces are provided depending on the weight distribution of the upper unit to prevent torsional force from acting. The thing I made was hot. However, in such an opening/closing mechanism equipped with a compression spring, the space for installing mounting members must be changed due to the change in size due to the change in the elastic force of the compression spring, which has the disadvantage of increasing costs due to an increase in the number of parts. It was hot.

<Purpose of the invention> In view of the above-mentioned drawbacks of the conventional device, the purpose of this invention is to provide a difference in the force acting on both ends in the axial direction during opening/closing operation, so that even when the weight distribution of the upper unit is uneven, the upper An object of the present invention is to provide an opening/closing mechanism that does not apply a force in a torsional direction to a unit and can fully utilize the simple structure and low cost inherent in a torsion bar.

<Structure and Effects of the Invention> The opening/closing mechanism of the image forming apparatus of this invention is such that the main body is divided into two upper and lower units, and the upper unit is configured to be openable and closable with one end as a fulcrum. In the opening/closing mechanism of an image forming apparatus equipped with a torsion bar that applies force, the torsion bar is constituted by two torsion bar springs, and the respective ends of the two torsion bar springs are in contact with each other and the torsion bar is opened and closed within a predetermined range. The upper mounting bracket and the lower mounting bracket are rotatable with respect to each other, and at least one of the upper mounting bracket and the lower mounting bracket includes an adjustment screw that abuts the end of the torsion bar spring in the torsional direction of the torsion bar spring. It is characterized in that it is provided so that the effective length can be changed.

According to the above-mentioned structure, the torsion bar, which is made of two elastic materials having the same elastic force, is attached to both the upper and lower units,
The torsion angle of the elastic material can be changed by changing the effective length of the adjustment screw. This allows the elastic forces of the two elastic materials that make up the torsion bar to be differentiated, and allows the elastic forces corresponding to the weight distribution of the upper unit to act on each of the application points. This means that no torsional force is applied to the upper unit, and the advantages inherent to the torsion bar, such as its simple, compact shape and low cost, can be effectively utilized.

<Embodiment> An embodiment of this invention will be described below using a copying machine as an example. FIG. 2 is an external view of a copying machine equipped with an opening/closing mechanism having a torsion bar, which is an embodiment of this invention, and shows the upper unit opened by the opening/closing mechanism.

The copying machine 1 is divided into upper and lower halves on a surface including a paper conveyance path from a side surface 1a on the paper feed section side to a side surface 1b on the paper discharge section side. This facilitates maintenance of the internal devices and unjamming operations. The upper unit 2 located above the paper transport path is provided with a document table 4 on its upper surface so as to be movable back and forth together with a document cover 4a. Further, inside the upper unit 2, a photoreceptor device 6, a developing device 7, etc. are installed. The photoreceptor device 6 includes a rotatable photoreceptor belt therein. The developing device 7 supplies developer to the surface of this photoreceptor belt.

In addition to these, the upper unit 2 is provided with an optical system device, a drive device, a drive transmission device, etc. (not shown). In particular, heavy items such as a drive device and a drive transmission device are provided at the rear side of the upper unit 2. Therefore, the weight distribution in the upper unit 2 is not uniform, and its rear part is heavier than its front part.

The lower unit 3 is provided with a fixing device 8 and a transport device (not shown). Further, a paper cassette 9 is attached to the side surface 1a of the lower unit 3 on the side of the paper feed section, and a paper discharge tray 10 is similarly attached to the side surface 1b of the paper discharge section. Further, the front cover 3a of the lower unit 3 can be opened toward the front by using a hinge at the lower side. As a result, the photoreceptor device 6, developing device 7, etc. included in the upper unit 2 are exposed.

The upper unit 2 can be opened and closed relative to the lower unit 3 in the direction of the arrow A or B using the side surface 1a on the paper feed section side as a fulcrum relative to the side surface on the paper feed section side. Inside the copying machine 1, a torsion bar 11 is provided near the side surface 1a on the paper feed section side, and applies a force to the upper unit 2 in the opening direction, that is, in the direction of arrow A. A lock lever 2a is provided near the side surface 1b of the upper unit 2 on the side of the paper discharge section. When the upper unit 2 is closed, the closed state is maintained by a lock mechanism (not shown). When opening the upper unit in the direction of arrow A, use the lock lever 2a.
in the direction of arrow C to release this locking mechanism. As a result, the upper unit 2 is opened in the direction of arrow A by the elastic force of the torsion bar 11. The upper unit 2 is closed by pressing it in the direction of arrow B against the elastic force of the torsion bar 11. At this time, the weight of the upper unit 2 acts and it can be closed relatively easily.

FIG. 3 is a schematic front view of a copying machine equipped with an opening/closing mechanism having the torsion bar.

When the upper unit 2 is closed, the interior of the copying machine 1 is constructed as shown in the figure. An image of a document placed on document table 4 is exposed on the surface of photoreceptor belt 6 located approximately in the center. A developer is supplied from the developing device 7 to the electrostatic latent image thus formed, and the image is visualized. Paper is fed from a paper cassette 9 mounted on the lower unit 3 in the direction of arrow E by the rotation of a paper feed roller 9a, and the visualized image on the photoreceptor belt 6 is transferred. After passing through the fixing device 8, this paper is placed in a paper output tray 10.
is discharged.

When the upper unit 2 is opened in the direction of arrow A, a conveyance path through which paper passes inside the copying machine 1 is exposed. The torsion bar 11 provided near the side surface 1a on the side of the paper feed section includes two elastic members (hereinafter referred to as torsion bar springs) 11a and 1.
1b. The torsion bar spring 11a is attached to the front of the upper unit 2 and the rear of the lower unit 3, while the torsion bar spring 11b is attached to the rear of the upper unit 2 and the front of the lower unit 3. .

FIG. 4 is an external view of the torsion bar and its mounting hardware that constitute the opening/closing mechanism.

Two torsion bar springs 11a and 11b constituting the torsion bar 11 intersect in the center and are in contact with each other. As a result, both torsion bar springs 11a and 11b give a torsion angle to each other. Both ends of one torsion bar spring 11a are held by an upper mounting bracket 21 at the front and a lower mounting bracket 22' at the rear, and both ends of the other torsion bar spring 11b are held by a lower mounting bracket at the front. 22 and rear upper mounting bracket 2
1'.

The upper mounting bracket 21 and the lower mounting bracket 22 are formed in a shape such that when a force in the direction of arrow F is applied to the upper mounting bracket 21, the upper mounting bracket 21 stops in the state shown in the figure. This also applies to the rear upper mounting bracket 21' and lower mounting bracket 22'. Therefore, when attaching the torsion bar 11 to the upper unit, the torsion bar springs 11a, 11b are given a torsional angle as shown in the figure using the upper mounting brackets 21, 21' and the lower mounting brackets 22, 22'. After that, attach the upper mounting bracket 2.
1, 21' are fixed to the upper unit.

FIGS. 1A and 1B are a rear view and a side view, respectively, of the opening/closing mechanism.

The upper mounting bracket 21' and the lower mounting bracket 22' are mutually rotatable by a boss 29. The upper mounting bracket 21' is fixed to the upper unit frame 31 with screws 41, and the lower mounting bracket 21' is fixed to the upper unit frame 31 with screws 41.
2' is attached to the lower unit frame 32 with a screw 42.
is fixed. A locking portion 23 is formed on the upper mounting bracket 21' and holds an end portion of the torsion bar spring 11b. A locking portion 24 is formed on the lower mounting bracket 22', and holds an end portion of the torsion bar spring 11a. Furthermore, the protrusion 25 formed on the upper mounting bracket 21' collides with the bent part 26 formed on the lower mounting bracket 22', thereby restricting the rotation of the upper unit frame 31 and the upper mounting bracket 21' in the direction of arrow A. .

An adjustment screw 27 is provided on the upper mounting bracket 21' so that its effective length can be changed. This adjusting screw 27 is secured to the upper mounting bracket 2 by means of a lock nut 28.
1'. The end of the adjustment screw 27 is in contact with the end of the torsion bar spring 11b. This rotates the adjustment screw 27,
When the end portion of the torsion bar spring 11b is moved in the direction of the arrow G, the end portion of the torsion bar spring 11b is moved in the direction of the arrow H. Therefore, torsion bar spring 1
The torsion angle of 1b increases, and the reaction force is arrow A.
The elastic force in the direction also increases.

Thereby, the force acting on the rear of the upper unit can be increased based on the weight distribution, and it is possible to prevent a torsional force from acting on the upper unit.

As described above, according to this embodiment, the torsion angle of one torsion bar spring is increased by the adjustment screw provided on the rear upper mounting bracket, increasing its elastic force, and acting on the heavier end of the upper unit. power can be increased. This allows a force corresponding to the weight distribution of the upper unit to be applied to each point of application, without causing twisting of the upper unit.

Although this embodiment has been described using the opening/closing mechanism in a copying machine as an example, the opening/closing mechanism can also be used in other image forming apparatuses in which the upper unit can be opened and closed with respect to the lower unit. Further, in this embodiment, an adjustment screw is provided on the rear upper mounting bracket, but an adjustment screw may be provided on the front upper mounting bracket, and furthermore, an adjustment screw may be provided on both upper mounting brackets. In addition, depending on the arrangement of other parts, adjustment screws can be attached to the lower mounting bracket, or can be provided on part of the upper and lower unit frames.

[Brief explanation of the drawing]

Figures 1A and B are front and side views, respectively, of an opening/closing mechanism with a torsion bar that is an embodiment of this invention, and Figure 2 is an external view of a copying machine equipped with the same opening/closing mechanism, with the upper unit opened. Indicates the condition. FIG. 3 is a schematic front view showing the configuration of a copying machine equipped with the same opening/closing mechanism. FIG. 4 is an external view of the opening/closing mechanism. 11... Torsion bar, 11a, 11b...
Torsion spring (elastic material), 21'... Upper mounting bracket (mounting position), 22'... Lower mounting bracket (mounting position), 27... Adjustment screw, 31... Upper unit frame, 32... Lower unit frame.

Claims (1)

[Claims for Utility Model Registration] An image forming apparatus that has a main body divided into upper and lower units and is configured to be able to open and close using one end as a fulcrum, and is equipped with a torsion bar that applies a force in the opening direction to the upper unit. In the opening/closing mechanism of the device, the torsion bar is constituted by two torsion bar springs, and an upper mounting bracket and an upper mounting bracket in which respective ends of the two torsion bar springs abut each other and are mutually rotatable within a predetermined range; A lower mounting bracket is provided, and at least one of the upper mounting bracket or the lower mounting bracket is provided with an adjustment screw that abuts the end of the torsion bar spring in the torsional direction of the torsion bar spring and whose effective length can be changed. An opening/closing mechanism for an image forming apparatus, characterized in that: