JPS58111961A - Transfer drum - Google Patents

Abstract

PURPOSE:To obtain a transfer drum whose insulating and elastic threadlike member is not loosened when stress is added to a frame body of a photosensitive body, by extending the threadlike member between both frames of the photosensitive body, in a state that it is stretched in advance against its elasticity. CONSTITUTION:An elastic body which has performed insulation covering to rubber or a coil spring wound comparatively thinly is used for a constituent base material of a transfer paper supporting body, and the transfer paper supporting body 9 is constituted by extending this insulating and elastic threadlike member between both frames 5, 6 in a state that it is stretched in advance against its elasticity. As for the transfer drum, since that elastic force is energized in advance to the insulating threadlike member 8 itself, slackness of the threadlike member 8, which is generated when it is extended between both the frames 5, 6, and when the frame body is distorted is absorbed by its self-elasticity, by which there is no possibility that a function for pringing transfer paper into press-contact with a photosensitive body 1 is not damaged.

Description

[Detailed description of the invention] This invention relates to a transfer drum for a copying machine.

In a copying machine, especially a color electrophotographic copying machine, for example, a photoreceptor drum is rotated three times, during which each latent image of an original document exposed through a color separation filter is sequentially developed with three types of colored toner. A color copy is obtained by sequentially overlapping toner images and transferring them onto the same transfer paper.

Therefore, in order to obtain a high-quality color copy, it is necessary to prevent the transfer paper from being misaligned when the three types of toner images are sequentially transferred onto a single transfer paper.

Therefore, in this type of copying machine, the transfer paper must be repeatedly and accurately conveyed in synchronization with the rotation of the photosensitive drum until one copying process is completed.

As a means for synchronously conveying the transfer paper with respect to the photoreceptor drum, for example, as shown in FIG. The leading end of the transfer paper S is clamped by the clamp claw 3, and the transfer paper S is clamped by the rotation of the photosensitive drum 1.
There is a device that transports synchronously.

By the way, in this type of copying machine, when transferring the toner image formed on the photoreceptor drum 1 onto the transfer paper S, it is necessary to know the back side of the transfer paper S and charge the transfer using the transfer charger 4, as is well known.

Therefore, as shown in FIG. 2, for example, this transfer drum 2 has a pair of ring-shaped frames 5 and 6 fixed to both ends of a stay 7 that is longer than the width of the transfer paper S to form a drum-shaped frame. On the other hand, between each of these ring-shaped frames 5.6,
A large number of insulating thread-like members 8 are stretched along the periphery of both frames 5 and 6 substantially parallel to the stay 7 to constitute a support 9 for the transfer paper S, and the support 9 is wound around the circumferential surface of the support 9. The transfer sheet S is configured so that the back surface thereof can be transferred and charged.

However, in this conventional transfer drum 2, since the insulating thread-like member 8 constituting the support 9 of the transfer paper S is made of a rigid material, the insulating thread-like member 8 is made of a rigid material. Tension becomes uneven. For this reason, this transfer drum has the disadvantage that the pressure of the transfer paper S against the photoreceptor drum 1 is uneven due to the uneven tension of the support 9, resulting in copy defects such as transfer omission.

In addition, this type of transfer drum 2 needs to be formed into a frame as shown in the figure due to its function, and thus has a structure with low rigidity against stress such as torsion. Therefore, if even a slight stress is applied to the transfer drum 2 when it is assembled into a copying machine, the tension of the insulating thread-like member 8 is relaxed due to distortion of the frame due to this stress, and the tension on the photosensitive drum 1 is relaxed. There was a drawback that the pressure contact function of the transfer paper S was impaired, resulting in poor transfer.

This invention was made in view of the above points, and its purpose is to prevent the thread-like member from relaxing when the insulating thread-like member is stretched on the frame of the transfer drum and when stress is applied to the frame. Our objective is to provide a transfer drum without

That is, the transfer drum according to the present invention focuses on the fact that the transfer paper support of the conventional transfer drum is composed of an inelastic thread-like member, and as a first embodiment thereof, the transfer paper support of this transfer paper support is The construction material is rubber or an elastic body made of a relatively thinly wound coil spring with an insulating coating.
Both frames 5 shown in FIG.
, 6 in a pre-stretched state against its elasticity to form a transfer paper support 9.

In the transfer drum of this embodiment, the insulating thread-like member 8 itself shown in FIG. The loosening of the filament member 8 that occurs during transfer is absorbed by its own elasticity, thereby eliminating the possibility that the function of pressing the transfer paper against the photoreceptor 1 will be impaired. Moreover, even if the thread-like member 8 is made into one single component, it will not loosen.

Therefore, according to the transfer drum of the present invention, it is possible to obtain high-quality copies without transfer omissions.

In the first embodiment, the stated purpose is achieved by constructing the insulating thread-like member itself from an elastic body such as rubber. The conventional thread-like member 8 may be biased with elasticity by linking the insulating thread-like member with an elastic body such as rubber or a spring at a suitable location at or near the end of each frame.

That is, for example, as shown in FIG.
．． When a non-elastic insulating thread-like member 8 is stretched between 6 and 6, one end (in the illustrated embodiment, the end closer to the frame 5) is stretched through an elastic body 10 made of rubber or a coil spring, etc. At this time, the elastic body lO is fixed to the frame in a state in which it has been stretched in advance against the tension force. Transfer drum 2 configured in this way
In addition to obtaining the same effects as the transfer drum of the first embodiment, since the thread-like member 8 is not limited to an elastic body, the material can be selected relatively freely. In addition, as the material for the insulating thread-like member, in general, an elastic material such as rubber or an inelastic material is often superior in durability, so the second embodiment shown in Fig. 3 is preferable. Its maintainability is also improved, as functional recovery can be achieved simply by replacing the elastic body 10.

The insulating thread-like member 8 in the second embodiment may be stretched in any of the ways shown in FIG. 4 (4) to (g).

However, in Fig. 4, the X mark at the end means that it is fixed with respect to the frame, and the ○ mark means that it is movable with respect to the frame, and the symbol 1
0 indicates an elastic body such as rubber or a coil spring.

Further, the elastic body 10 does not necessarily need to have one end fixed to the frame, and may be connected to the intermediate portion of the thread-like member 8, for example, as shown in FIG.

Note that the elastic body 10 in the second embodiment described above has the following characteristics when considering uniform pressure contact of the transfer paper S to the photoreceptor drum 1.
It is preferable that the arrangement location be removed from the transport area of the transfer paper S.

However, in order to apply sufficient tightening elasticity to the thread-like member 8, the length of the elastic body 10 cannot be made too short. Therefore, if this elastic body 10 is disposed outside the transfer area of the transfer paper S, the width of one transfer drum increases by the length thereof, resulting in a problem of increasing the size of the copying machine.

The transfer drum shown in Fig. 6 has a third type that eliminates this problem.
FIG. 2 is a partial perspective view showing an embodiment of the invention.

That is, in this third embodiment, the elastic body 10 is made of a plate spring, and this plate spring is fixed to a frame, and a thread-like member 8 is stretched on the free end of the transfer drum to constitute a transfer paper support. It is. In order to solve the above-mentioned problems using the elastic body 10 in the second embodiment, for example, as shown in FIG. A groove 6α (5α) to be inserted is formed, and the elastic body 1 is inserted into this groove 6α (5α).
A structure may be used in which the 0 is buried and prevented from protruding into the transfer paper transport color gamut.

As described above, according to the present invention, a transfer drum is provided in which the insulating thread-like member constituting the transfer paper support does not loosen during assembly.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a copying machine to which the transfer drum of the present invention is applied, FIG. 2 is a perspective view of the transfer drum of the copying machine, and FIG. 3 is a schematic diagram showing an embodiment of the present invention. , 4th
5 and 5 are explanatory diagrams illustrating how to tension the thread-like member in the above embodiment, FIG. 6 is a partial perspective view of another embodiment of the present invention, and FIG. 7 is a further embodiment of the present invention. FIG. 1... Photosensitive drum, 2... Transfer drum, 5.
6... Frame, 7... Stay, 8... Insulating thread-like member, 9... Transfer paper support, 10... Elastic body.

Claims (1)

[Claims] 1. A drum-shaped frame is formed by fixing a pair of ring-shaped frames to both ends of a stay that is longer than the width of the transfer paper, and between each of the ring-shaped frames, A transfer drum of a copying machine in which a transfer paper support is constructed by stretching a large number of insulating thread-like members along the periphery substantially parallel to the stay, characterized in that the insulating thread-like members are biased with elasticity. transfer drum. 2. The transfer drum according to claim 1, wherein the insulating thread-like member itself is a stretchable elastic body. 3. The transfer drum according to claim 1, wherein the end of the rigid insulating filament member close to the frame or a suitable position in the vicinity thereof is connected by an elastic body.