JPS6262372A - Positioning device for image and transfer paper of copying machine - Google Patents

Abstract

PURPOSE:To position exactly an image on the sensitive body and transfer paper in the transfer section even when an operation speed of a copying machine is changed by so constituting that a gate means sends out transfer paper to a transfer section simultaneously with a detecting means detects an opening provided on the edge of a sensitive body. CONSTITUTION:Transfer paper 28 sent out from a paper feeding tray 26 is stopped at the position of a gate roll 32. Simultaneously with detection of an opening provided on the side edge of a beltlike sensitive body 10 by a photosensor 40, the roll 32 is driven, and the paper 28 is carried to a transfer section 34, and a toner image is transferred. As the transfer paper is carried to the transfer position in conforming timing with detection, the transfer paper can be positioned accurately even when speed of operation of the copying machine is changed by change of temperature in the machine or wear of the sensitive body driving roll etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a device for aligning a toner image on a photoreceptor with a transfer sheet in a copying machine.

Conventional technology In medium-sized and small-sized electrophotographic copying machines, a cylindrical photosensitive drum is used as a photosensitive member, and an electrostatic latent image formed on the photosensitive drum is developed by a developing device as a toner image. A common method is to transfer the image onto a transfer sheet made of plain paper. As described above, electrophotographic copying machines using drum-shaped photoreceptors have become the mainstream among medium-sized and small-sized copying machines because the entire copying machine can be constructed compactly.

When a drum-shaped photoreceptor is used, the photoreceptor drum itself has a rigid structure and the distance between the electrostatic latent image formation position on the photoreceptor drum and the transfer position is relatively small, so the photoreceptor drum at the transfer position Registration between the upper toner image and the transfer paper can be achieved relatively accurately, and is not significantly affected by changes in internal temperature or aging.

Recently, copying machines using belt-shaped photoreceptors have been proposed and put into practical use, particularly in the field of high-speed copying machines. When such a belt-shaped photoreceptor is used, the photoreceptor at the position where the electrostatic latent image is formed can be kept flat and flat, making it possible to use flash exposure, making it particularly suitable for high-speed copying machines. It can be said that

Problems to be Solved by the Invention However, in a copying machine using such a belt-shaped photoreceptor, it is generally difficult to determine the position at which an electrostatic latent image is formed on the photoreceptor and the position at which this electrostatic latent image is developed with toner. The position where the toner image is then transferred to the transfer paper is relatively far away. Therefore, if the moving distance of the photoconductor per unit time (process speed) changes due to a change in the diameter of the belt-shaped photoconductor driving roll due to a change in the internal temperature of the machine, or due to wear of the belt-shaped photoconductor driving roll, etc. , the time it takes for the image formed on the photoreceptor to arrive at the transfer section changes.

On the other hand, in conventional copying machines, the transfer paper is fed by a paper feeder based on the electrostatic latent image forming position on the photoreceptor, and the timing between the toner image on the photoreceptor and the transfer paper is determined in the transfer section. As mentioned above, if the time for the image on the photoconductor to arrive at the transfer section changes, the photoconductor will move by the distance that the transfer paper moves within the changed time.
There was a problem that the image of F was misaligned with the transfer paper.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to overcome the above-mentioned drawbacks of the prior art and to provide an image in a copying machine in which the position of the image on the photoreceptor and the transfer paper do not shift in the transfer section even if the process speed of the copying machine changes. An object of the present invention is to provide a transfer paper alignment device.

Means for Solving the Problems In order to solve the problems of the prior art described above, the present invention forms a toner image corresponding to an original to be copied on a photoreceptor, and transfers this toner image to a transfer sheet. In a type of copying machine, at least one notch or opening is provided in the side edge of the photoreceptor, and a detection means for detecting the notch or opening is provided near the upstream side of the transfer portion of the photoreceptor, and the photoreceptor is A gate means is provided to temporarily stop the transfer paper conveyed by the conveyance means in order to align the upper toner image and the transfer paper, and the detection means detects the notch or opening on the photoreceptor and the timing is determined. A device for aligning an image and a transfer sheet of a copying machine is provided, characterized in that a control means is provided for driving the gate means and sending out the transfer sheet to a transfer section.

The gate means is driven at the same time as or after a predetermined period of time when a notch or opening provided on the photoreceptor is detected by a detection means such as a transmission type food sensor. As a result, the transfer paper that has been temporarily stopped by the gate means is sent out to the transfer section, and the toner image on the photoreceptor can be accurately transferred onto the transfer paper at the transfer section.

In other words, in the present invention, since the image on the photoreceptor and the transfer paper are aligned using the position of the detection means provided near the upstream of the transfer section as a reference point, even if the temperature changes or the drive roll Even if the time from when an image is formed on the photoreceptor to when it arrives at the transfer section changes due to wear or the like, highly accurate alignment between the image on the photoreceptor and the transfer paper can be achieved.

Embodiments of the present invention will be described in detail below with reference to the drawings.

衷-ULJ! 1 FIG. 1 shows a schematic configuration diagram in which the present invention is applied to a copying machine employing a belt-shaped photoreceptor. The belt-shaped photoreceptor 10 is endlessly wound around a drive roll 12 and idler rolls 14 and 16, and is rotated in the direction of the arrow by rotationally driving the drive roll 12. Charged corotron 1
8, a charge of a predetermined polarity is uniformly applied to the belt-shaped photoreceptor 10, and then an image exposure bag @20 applies an electric charge to the original 22.
An electrostatic latent image corresponding to is formed on the photoreceptor 10.

The image exposure device 20 can almost instantaneously form an electrostatic latent image corresponding to the original 22 on the belt-shaped photoreceptor 10 by employing flash exposure, for example.

However, the electrostatic latent image of the document 22 may be formed on the photoreceptor 10 by conventionally known scanning exposure.

The electrostatic latent image on the photoreceptor 10 is then developed into a visible image by a developing device 24 such as a magnetic brush developing device.

Reference numeral 26 denotes a paper feed tray, in which transfer papers 28 are stacked and stored. The transfer paper 28 is sent out from the paper feed tray 26 by rotating the feed roll 30, and after being timed with the toner image on the photoreceptor 10 by the gate roll 32, the transfer paper 28 is sent to the transfer position.

At the transfer position, the toner image on the photoreceptor is transferred onto the transfer paper 28 by the transfer corotron 34, and the toner image on the transfer paper is fixed by a fixing device (not shown) to obtain a permanent copy image. - The residual toner image on the photoconductor is removed by a cleaning device such as a fur brush cleaning device.
6, and one copy cycle is completed.

Reference numeral 38 denotes openings provided at the side edges of the belt-shaped photoreceptor 10, and in this embodiment, two openings are provided. However, the number of openings 38 is not limited to two, and may be provided with only one, or approximately three or more. In addition, instead of the opening, there is a hole at the side edge of the belt-like photoreceptor 10.
One or more notches may be provided. 4
0 is a photosensor provided near the upstream side of the transfer corotron 34, and is composed of a light emitting element 42 and a light receiving element 44.

The feed roll 30 and the gate roll 32 are each connected to a driving means, and are configured to be driven by a control means (not shown) in synchronization with the image formed on the photoreceptor 10.

The electrostatic latent image formed on the belt-like photoreceptor 10 is developed into a visible image by the developing device wi24, and then sent to the transfer section. On the other hand, the transfer paper 28 sent out from the paper feed tray 26 by the feed roll 30 is conveyed to the position of the gate roll 32. At this time, the gate roll 32 rotates and the transfer paper 28 is kept at the position of the gate roll 32. It will stop.

At the same time that the photosensor 40 detects the opening 38 on the photoreceptor 10, the gate roll 32 is rotationally driven by a signal from a control means (not shown). As a result, the transfer paper 28
is conveyed to the transfer position, and the toner image on the photoreceptor 10 is transferred onto the transfer paper 28 by the transfer corotron 34.

In the embodiment described above, the gate roll 32 is driven at the same time as the photo sensor 40 detects the opening 38 on the photoreceptor 10, but the gate roll 32 is driven at a certain predetermined time after the photo sensor 40 detects the opening 38. Even after hours. In this case, the gate roll 32 will be placed closer to the transfer corotron 34.

Furthermore, in the present invention, the closer the photosensor 40 is placed to the transfer corotron 34, the more the photoreceptor 10
The alignment between the upper image and the transfer paper 28 can be achieved with higher precision.

Referring to FIG. 2, it is easy to understand the relationship between the image on the photoreceptor, the drive of the gate roll, and the paper feed from the time the image is created on the photoreceptor until it is transferred to a transfer sheet.

That is, as long as the transfer paper is stopped by the gate roll, according to the present invention, accurate alignment between the image on the photoreceptor and the transfer paper can be achieved.

As detailed above, the present invention provides one or more notches or openings in the side edge of a photoreceptor, and detects the notches or openings by a detection means disposed near the upstream side of the transfer position. Since the transfer paper is conveyed to the transfer position in synchronization with this detection, the process speed of the copying machine does not change due to changes in the internal temperature of the machine or wear of the photoconductor drive. Even in this case, the effect of always achieving accurate alignment between the image on the photoreceptor and the transfer paper is achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a copying machine employing the alignment device of the present invention, and FIG. 2 is a time chart showing the relationship between the photoreceptor, gate roll, and paper feeding from image creation to transfer. DESCRIPTION OF SYMBOLS 10... Belt-shaped photoreceptor, 18... Charging corotron, 20... Image exposure device, 24... Developing device, 3
2... Gutrol, 34... Transcription corotron,
36...Cleaning III, 38...Opening,
40...Photo sensor.

Claims (1)

[Claims] In a type of copying machine that forms a toner image corresponding to a document to be copied on a photoreceptor and transfers this toner image to a transfer sheet, at least one notch or opening is provided at the side edge of the photoreceptor, and the toner image is transferred to a transfer sheet. A detection means for detecting the notch or opening is provided near the upstream side of the transfer section of the photoconductor, and once the transfer paper conveyed by the conveyance means is provided in order to align the toner image on the photoconductor and the transfer paper at the transfer section. A control means is provided to stop the transfer sheet, and to drive the gate means in synchronization with the detection of the notch or opening on the photoreceptor by the detection means to send the transfer sheet to the transfer section. Copying machine image and transfer paper alignment device