JPH04143771A - Electrophotographic image formation device - Google Patents

Abstract

PURPOSE:To eliminate the sudden opening and closure of an upper unit and to improve the safety of operation by providing a gear which meshes a sector gear to the upper unit across an oil damper and making the support force of a spring provided at this end part smaller than the support force of a spring at the other end part. CONSTITUTION:When the upper unit 2 is opened or closed by being hopped up from or down to a lower unit 1, the gear 18 engaging the arcuate sector gear 11 rotates about the upper unit 2, but this gear 18 rotates about the upper unit 2 through the oil damper 17 fixed to the upper unit 2. The oil damper 17 generates a resistance force corresponding to the rotating speed of the gear 18 and this force operates in the direction wherein the gear 18 is inhibited from rotating, so the opening/closing speed is determined corresponding to the opening/closing force of the upper unit 2 and even when the large load of the upper unit 2 is applied on a support part, the upper unit 2 is neither opened nor closed abruptly. Consequently, the operation is performed more safely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an electrophotographic image forming apparatus having a main body divided into upper and lower units which are pivotally connected to each other at one end and can be opened.

Conventional technology In electrophotographic image forming apparatuses such as electrophotographic copying machines, laser printers, and facsimile machines, it is necessary to replace developing devices, photoreceptors, etc.
In order to facilitate maintenance such as replacing consumables or clearing jammed recording paper, the main body of the device is divided into two units, upper and lower, which are pivoted to each other at one end, and the upper unit can be lifted up. So-called clamshell type devices that can be opened and closed are increasingly being adopted, especially in small-sized devices.

As illustrated in FIG. 2, the opening/closing mechanism of this type of image forming apparatus includes torsion springs 4 and 5 near both ends of the pivot shafts 3 of the lower unit 1 and the upper unit 2, which bias both units in the direction of opening.
, which have sufficient elasticity to hold open the upper unit 2, which carries a considerable weight such as an imaging unit.

In the opening/closing mechanism with such a configuration, the torsion spring 4°5 has strong elasticity, so when installing the fairly heavy upper unit by aligning it with the set position of the movable hinge member 6. It was dangerous to perform assembly work while supporting the upper unit. In addition, a strong load is applied to the upper unit, and the strength around the fulcrum must be increased.
There was a drawback that it led to high costs. Furthermore, when the weight of the upper unit is reduced by removing replacement parts from the upper unit 2, the upper unit suddenly jumps up due to the force of the torsion spring 4.5, making it difficult to control the opening/closing speed.

FIG. 3 is a diagram showing one end of a pivoting portion of another example of an opening/closing mechanism for a clamshell type device. This device consists of a hinge part 7 fixed to the lower unit 1 and a hinge member 9 having a boss part 8 that engages with the rotation fulcrum 6 of the lower unit 1 and fixed to the upper unit, instead of a torsion spring. The weight of the upper unit is supported by two torsion bars 10 whose ends are bent in opposite directions. In this case as well, the above-mentioned problems still exist.

Problems to be Solved by the Invention In view of the above-mentioned problems of the conventional clamshell-type image forming device having the opening/closing mechanism configured as described above, the present invention has been made to solve the above-mentioned problems in the conventional clamshell type image forming apparatus having the opening/closing mechanism configured as described above. An object of the present invention is to provide a clamshell type image forming apparatus having an easy opening/closing mechanism.

Means for Solving the Problems In order to solve the above problems, the clamshell type electrophotographic image forming apparatus of the present invention has a structure in which the two units are fixed to the lower unit at one end of the pivoting edges of the two units. A fan-shaped gear having teeth on an arc centered on a pivot axis of the upper unit, and a gear that is rotatable with respect to the upper unit and meshes with the sector-shaped gear via an oil damper fixed to the upper unit. However, it is characterized in that the supporting force of the spring provided at the end is smaller than the supporting force J of the spring provided at the other end.

Function: Since the opening/closing mechanism of the electrophotographic image forming apparatus of the present invention is constructed as described above, when the upper unit is flipped up or down relative to the lower unit to open/close, it engages with the arcuate fan-shaped gear. A gear rotates relative to the upper unit, and this gear rotates relative to the upper unit via an oil damper fixed to the upper unit. The oil damper generates a resistance force that corresponds to the rotational speed of the gear, and this force acts in a direction that prevents the rotation of the gear, so the opening and closing speed is determined according to the force with which the upper unit tries to open and close, and the large load on the upper unit Even if the force is applied to the support part, or if a heavy component is removed from the upper unit, the closing or opening speed will automatically be determined depending on the magnitude of the force in the closing or opening direction, and the upper unit will suddenly move. You can work safely without having to close or open it. Also, since the oil damper bears part of the force in the opening/closing direction, the load applied to the upper and lower units is reduced by that amount. Therefore, the supporting force of the spring on the side where the gear and oil damper are provided can be reduced accordingly.

Embodiments Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a perspective view showing an upper and lower unit opening/closing mechanism of a clamshell type electrophotographic image forming apparatus to which the present invention is applied.

In the figure, the upper unit 2 can be opened and closed by pivoting about an axis 3 relative to the lower unit 1 as shown by double-headed arrows. A fan-shaped gear 11 having teeth cut in an arc centered on the axis 3 is fixed to one end of the pivoting edge of the lower unit 1, and is attached to a support provided on the pivoting shaft of the upper unit 2. A shaft 12 is rotatably supported by a bearing 13 provided on the fan-shaped gear 11. A support shaft 14 provided at the other end of the pivot shaft of the upper unit 2 is rotatably supported by a bearing 6 provided on a bracket 15 fixed to the lower unit 1.

A geared oil damper 17 is fixed to the side surface of the upper unit 1 on which the support shaft 12 is provided, and its gear 18 meshes with the teeth of the sector-shaped gear 11.

Torsion springs 19 and 20 are provided that wind around the support shafts 12 and 14 on both sides and bias the upper and lower units in the direction of opening.One arm of each torsion spring is attached to the upper unit 2 and the other arm is attached to the lower unit 1. is fixed.

When the upper and lower units 1 and 2 are opened and closed, the oil damper 1
7 gear 18 is a fan-shaped gear 11 fixed to the lower unit 1.
Since the upper unit 2 is meshed with the teeth of the upper unit 2, it rotates at a speed corresponding to the rotating speed of the upper unit 2, and at this time, the oil in the oil damper generates a resistance force depending on the flow speed due to the viscosity of the oil.

The upper unit 2 rotates at a speed where this resistance force and the force for rotating the upper unit 2 are balanced. Therefore, in order to rapidly rotate the upper unit 2, a large number J is required.
The rotation in the closing direction due to the weight of the upper unit 2 and the rotation in the opening direction due to the weight reduction of the upper unit when a heavy unit attached to the upper unit is removed are not as fast as on the left due to the resistance of the oil damper. automatically determined,
It is possible to slowly close or open the door at a speed close to a constant speed (although the horizontal position of the center of gravity changes as it rotates, so the speed will not be constant, so the speed will not be constant), allowing you to proceed with the work safely. can.

The force supporting the load of the upper unit 2 when closing the upper unit 2 is supported by the torsion spring 20 at the left end in FIG.
Support with resistance of 7.

Therefore, the supporting force of the torsion spring 19 can be made smaller than the supporting force of the torsion spring 20. By being able to reduce the supporting force of the torsion springs, the structural strength around the support portion can be reduced, which also contributes to cost reduction.

Effects As described above, according to the present invention, in a clamshell type electrophotographic image forming apparatus, it is difficult to assemble the lower unit of the upper unit, which is heavy, and to remove the heavy parts from the lower unit. This prevents the upper unit from suddenly opening when the upper unit is opened, improving work safety, and reducing the structural strength of the support portion, resulting in cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the upper and lower unit opening/closing mechanism of the embodiment of the present invention, FIG. 2 is a perspective view showing the overall schematic configuration of a conventional clamshell electrophotographic image forming apparatus, and FIG. 3 is a perspective view showing the conventional upper and lower unit opening/closing mechanism. FIG. 7 is a perspective view showing another example of the unit opening/closing mechanism. 1 - Lower unit 2 - Upper unit 3 - Upper and lower unit pivot shaft 11... Sector gear 12.14 - Support shaft 13.16 - Bearing 15 Bracket 17 Oil damper 18 - Gear 19.20 - Torsion spring heel Skein

Claims (1)

[Claims] The main body is divided into two upper and lower units, both units are pivotally connected to each other at one end edge, and the upper and lower parts are connected to each other by springs that bias both ends of the pivoting end edge in the direction of opening both units. In an electrophotographic image forming apparatus that supports the weight of the unit, teeth are fixed to the lower unit at one end of the pivoting edges of the two units and arranged on an arc centered on the pivot axis of the two units. a sector-shaped gear, and a gear that is rotatable relative to the upper unit and meshes with the sector-shaped gear via an oil damper fixed to the upper unit, and the supporting force of the spring provided at the end is applied to the other end. An electrophotographic image forming apparatus characterized in that the supporting force is smaller than that of a spring provided at an end.