JPS60101568A - Transfer device of copying machine - Google Patents

Abstract

PURPOSE:To obtain a copy image without any transfer unevenness by providing a detecting means which detects the contacting state of a contacting part between a charge holding drum and a transfer roller near the contacting part. CONSTITUTION:Two detecting means each consisting of a light emitting element 3 and a photodetecting element 4 are arranged at both ends of the contacting part in one-to-one relation. Thus, the two pairs of light emitting and photodetecting elements 3 and 4 are arranged, and consequently a photodetection signal is sent out of either photodetecting element 4 when the photosensitive drum 1 and transfer roller 2 contact each other to the overall width in a balanced state; when the photosensitive drum 1 and transfer roller 2 enters twist relation and become unparallel, gaps are formed at both ends of the contacting part between the both and light from the light emitting elements 3 reach the photodetecting element 4 through those gaps to send out photodetection signal, so that the drum 1 and roller 2 are controlled to the parallel state.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a transfer device for a copying machine.

[Prior art]

Generally, in an electrophotographic copying machine, a photoreceptor drum, for example, is used as a charge holding member, and an electrostatic latent image corresponding to one image of a document is formed on the photoreceptor drum, and this is developed using a dry developer. A toner image is developed by a one-dimensional device, and this toner image is transferred and fixed onto copy paper to obtain a copy image.

As a transfer means for transferring the toner image onto the copy paper during the copying process, a transfer roller to which a bias voltage is applied is known.

However, with a transfer means using a transfer roller, if a jam occurs in the transfer section during use, the transfer roller supported by the spring means will be biased when the jammed paper is removed, resulting in the problem shown in Figure 1 (5). ), (As shown in Bl, a deviation such as twisting occurs between the photosensitive drum 1 and the transfer roller 2, and the two cannot maintain parallelism.

For this reason, the photoreceptor drum 1 and the transfer roller 2 are in contact only at the center, and a gap is created at both ends, resulting in a difference in transfer pressure. However, there was a drawback that there was a difference in image density and uneven transfer occurred.

This deviation between the two occurs not only when jammed paper occurs, but also when copy paper is conveyed unevenly due to the size of the paper.

Further, such a transfer roller shift phenomenon is particularly likely to occur in a device having a two-stage transfer mechanism in which an intermediate transfer roller is interposed between the photoreceptor drum and the transfer roller. In other words, it is difficult to arrange the photoreceptor drum, intermediate transfer roller, and transfer roller in parallel, maintain this state, and apply appropriate pressure between them from the woman. Deviations caused by displacement, etc. are not caused by force or strain, but even if initial settings such as sufficient parallelism are made, deviations such as twisting occur gradually during operation due to force and pressure means such as springs used to apply pressure. occurs.

Conventionally, in order to deal with this, the transfer ink pressure is set high to prevent uneven transfer due to misalignment. However, - obtaining multiple copies by exposure,
When the so-called Lite/-/Yon method is adopted, there is a drawback that when the transfer diameter is increased, charge injection occurs, resulting in image fogging.

[Purpose of the invention]

The present invention detects the contact state at the contact portion between the charge holding drum and the transfer roller, thereby making it possible to maintain parallelism between the two, thereby preventing uneven transfer and obtaining a good copied image. It is an object of the present invention to provide a transfer device as described above.

[Summary of the invention]

In a copying machine transfer device configured to transfer a toner image formed on a charge retention drum onto a recording paper surface using a transfer roller, a contact portion is placed near a contact portion between the charge retention drum and the transfer roller. A detection means is provided to detect the state, and the transfer roller adjustment means can be adjusted manually or automatically based on the detection signal, correcting for twisting between the charge holding drum and the transfer roller, etc., and making accurate adjustments. This is to maintain parallelism.

[Embodiments of the invention]

Next, examples of the present invention will be described. FIG. 2 is a front view of one embodiment of the transfer device according to the present invention, and FIG.
is a side view thereof. In the figure, 3 is a light emitting element such as a light emitting diode, and 4 is a light receiving element such as a phototransistor. The photosensitive drum 1 and the transfer roller 2 are arranged at positions that do not affect the paper conveyance path, and on opposite sides of their contact parts.
The light receiving element 4 is arranged so that the light receiving element 4 can receive the transmitted light from the light emitting element 3 even if there is a gap in the contact portion between the light emitting element 3 and the light emitting element 3.

In this embodiment, two sets of detection means each consisting of the light emitting element 3 and the light receiving element 4 are provided at each end of the contact portion.
They are arranged in groups.

By arranging the two sets of detection means consisting of the light emitting element 3 and the light receiving element 4 in this manner, the photosensitive drum l and the transfer roller 2 are in a parallel state and are in contact with each other over the entire width. 1, the photosensitive drum 1 and the transfer roller 2 are twisted and are no longer parallel to each other, as shown in FIG. 1 (5) (Bl). Since a gap is created at both ends of the contact portion between the two, the light from the light emitting element 3 can be transmitted through the gap directly, reflected from the roller or drum surface, or even narrowly. Due to the diffraction phenomenon caused by passing through the gap,
The light reaches the light receiving element 4 and a light detection signal is transmitted.

By operating the display device using a light detection signal caused by the occurrence of this twist, etc., the adjustment means of the spring support portion of the transfer roller 2 can be manually adjusted to correct the parallelism.
Alternatively, the adjusting means may be configured to automatically adjust according to the amount of received light to maintain parallelism based on the light detection signal.

The detection means consisting of the light-emitting element 3 and the light-receiving element 4 can be used by simply arranging the light-emitting element 3 and the light-receiving element 4 in pairs when a gap due to misalignment between the photoreceptor drum 1 and the transfer roller 2 occurs only at one end. , the deviation can be detected, but in general,
Since a gap occurs at both ends or at one end, it is possible to detect the displacement of the transfer roller 2 by arranging at least two sets.

Detection of displacement between the contact portions between the two may be performed at all times during operation of the copying machine, but if a light weight detection means using light is used as in the above embodiment, detection of displacement between the contact portions of the two may be performed through the transfer portion. If toner adheres to the photoreceptor drum 1 etc., even if there is a gap between the two, it may not be possible to detect the transmitted light, so this detection method may not be able to detect contact. Good results can be obtained by performing the section misalignment detection operation when copying is restarted after a long period of no copying, or when the photosensitive drum is rotated.

FIG. 3 shows a configuration example in which the present invention is applied to a roller transfer device having a two-stage transfer mechanism. In this case as well, a light emitting element 3 and a light receiving element 4 are arranged on both sides of the contact portion between the intermediate transfer roller 5 and the photoreceptor drum 1, so that the photoreceptor drum l
This is to detect the deviation of the contact portion between the intermediate transfer roller 5 and the intermediate transfer roller 5. Note that 6 indicates copy paper.

The present invention is designed to detect the positional relationship such as twisting between the photoreceptor drum and the transfer roller in the transfer device, but the means for detecting such twisting etc. is not suitable as in the case of indaresozoyon development etc. , it can also be applied to a device having a plurality of roller members that are in contact with each other.

〔Effect of the invention〕

The present invention provides a detection means for detecting the contact state of the contact portion near the contact portion between the charge retention drum and the transfer roller, detects a shift or twist between the charge retention drum and the transfer drum, and manually detects the contact state of the contact portion. Alternatively, since the positional relationship between the two can be automatically corrected so that they are always kept parallel, there is no need to increase the transfer bias, and a good copy image without uneven transfer can be obtained.

[Brief explanation of drawings]

Fig. 1 (5) is a front view of the transfer device showing a twisted state of the transfer roller, Fig. 1 CB+ is a view of the device shown in Fig. 1 (5) from below, and Fig. 2 (5) 2 is a front view of one embodiment of the transfer device according to the present invention, FIG. 2 is a side view thereof, and FIG. 3 is a plan view of another embodiment of the present invention. Photosensitive drum, 2 is a transfer roller, 3
4 is a light-emitting element, 4 is a light-receiving element, and 5 is a transfer roller. Patent applicant Orinokus Optical Industry Co., Ltd. (A) (A) 3rd checkpoint + rf! 1 (B) 2nd leap (B)

Claims (1)

[Claims] In a copying machine transfer device configured to transfer a toner image formed on a charge holding drum onto a recording paper surface using a transfer roller, a contact portion is provided near a contact portion between the charge holding drum and the transfer roller. A transfer device characterized in that it is provided with a detection means for detecting a contact state of the.