JPH0446287Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to a copying apparatus that forms an electrostatic latent image on a photoreceptor to copy a predetermined image.

``Prior art'' Copying machines that use the so-called xerography method expose an image on a document onto a photoreceptor to form an electrostatic latent image, which is then developed and transferred to make a copy. .

The method for forming an electrostatic latent image on a photoconductor is as follows:
A common method is to irradiate an image on a document with a light source and guide the reflected light onto a photoreceptor using an optical system using lenses and mirrors.

On the other hand, the image on the document is converted into an electrical image signal, and the image signal is supplied to an LED array in which light emitting elements such as light emitting diodes are arranged in a row, and to a liquid crystal shutter that selectively transmits the light from the light source. Another well-known method is to irradiate the surface of a photoconductor and form an electrostatic latent image while scanning the photoconductor.
60-147725, etc.).

In the present invention, devices for converting an image signal into an optical signal to form an electrostatic latent image on a photoreceptor are collectively referred to as a latent image writing head.

``Problem that the invention attempts to solve'' Here, in the latent image writing head, the LED array is determined by the energy (brightness) of the output light of each light emitting element.
is relatively small, so in order to form an electrostatic latent image with sufficient contrast, an irradiation time longer than a certain level is required, and there is a problem that it is difficult to increase the writing speed.

For example, as shown in FIG. 2, a belt-shaped photoreceptor 1 is charged to -1000V and conveyed in the direction of arrow 2 at a process speed of 200 mm per second, and an electrostatic latent image 4 is formed by a latent image writing head 3. -150V if
Exposure of a so-called white background area, which requires static electricity removal, requires irradiation of 3 to 5 μW of light energy per pixel. For a copying machine set to form an electrostatic latent image under these conditions, if the process speed is increased to 400 mm per second, only about 1.5 μW of light energy will be irradiated to expose the white background, and the photoreceptor will be Static electricity is only removed to about -500V,
The contrast of the copied image becomes insufficient.

For this reason, conventional latent image writing heads of this type have a process speed of up to 250 m/sec.
It was difficult to raise it above mm.

On the other hand, when a liquid crystal shutter is used, it is possible to select a light source with relatively large light energy. However, since the opening and closing speed of the liquid crystal shutter is slow, it has been difficult to increase the process speed.

This invention was developed with the above points in mind.
It is an object of the present invention to provide a copying apparatus capable of increasing the process speed even when using a latent image writing head having a relatively slow writing speed.

``Means for Solving the Problems'' The copying apparatus of the present invention includes a photoconductor, a latent image writing head that forms an electrostatic latent image on the photoconductor, and a photoconductor that conveys the photoconductor in a predetermined direction at a predetermined speed. a photoreceptor conveying means for scanning to form an electrostatic latent image;
The apparatus is characterized by comprising a head conveyance means for conveying the latent image writing head in the same direction as the conveyance direction of the photoreceptor at a relative speed different from the conveyance speed thereof.

``Operation'' As described above, the copying apparatus of the present invention conveys the photoreceptor at high speed, and conveys the latent image writing head for forming an electrostatic latent image thereon in the same direction as the conveyor. Then, scanning for forming an electrostatic latent image is performed based on the difference in relative speed. In this way, the relative speed can be slowed down to allow enough time for writing, while still allowing the process speed to be fast enough.

Embodiment FIG. 1 is a schematic diagram showing an embodiment of a copying apparatus of the present invention.

This copying apparatus uses an endless belt-shaped photoreceptor 1,
Guided by four guide rollers 6a to 6d,
This guide roller 6b is driven by a motor 11 via a transmission belt 11a, and is configured to convey the photoreceptor 1 in the direction of arrow 8 at a constant speed. Here, this motor 11 will be referred to as photoreceptor conveying means in the present invention.

On the other hand, a guide belt 1 is passed around a pair of rollers 7a and 7b over the inner part surrounded by the photoreceptor 1.
3 is provided, and a latent image writing head 3 is fixed on this guide belt 13. This one roller 7b is connected to the motor 1 via a transmission belt 12a.
It is driven by 2. This motor 12 will be referred to as a head conveying means in the present invention.

This head conveying means 12 carries the latent image writing head 3 when forming an electrostatic latent image on the photoreceptor 1.
is conveyed in the direction of the solid arrow 14 at a relative speed different from the conveyance speed of the photoreceptor 1. Note that the latent image writing head 3 is attached to the photoreceptor 1 along the guide rail 15.
conveyed parallel to the This relative speed is precisely matched to the scanning speed for formation of the electrostatic latent image. In order to carry out such highly accurate conveyance, a pulse motor or the like is used for both the photoreceptor conveying means 11 and the head conveying means 12. Further, the head conveying means 12 may be of any type as long as it can reciprocate the latent image writing head 3, and may be one using a linear motor or the like. When the formation of the electrostatic latent image is completed, the head conveying means 12 is reversely rotated to pull the latent image writing head 3 back in the direction of the dashed arrow 15.

Note that a static eliminator 21 , a cleaning device 22 , a charger 23 , a developing device 24 , a transfer device 26 , and a paper peeling device 27 are provided around the outer periphery of the photoreceptor 1 .
The copy paper 25 is transferred from a paper feeder (not shown) to the transfer device 2.
6.

The copying apparatus of the present invention having the above configuration operates as follows.

First, the conveying speed of the photoreceptor conveying means 11 is set to
Select 500mm. Further, the conveying speed of the head conveying means 12 is selected to be 250 msec/sec.

When copying starts, the photoreceptor 1 is neutralized by a static eliminator 21, and unnecessary toner is removed from the cleaning device 22.
, and charged to -1000V in a charger 23, for example. At this point, the head conveying means 12 starts conveying. Next, an image signal corresponding to the copied image is sent from a signal processing device (not shown) to the latent image writing head 3, and the photoreceptor 1
An electrostatic latent image is formed.

The photoreceptor 1 has a structure in which a photosensitive material film is formed on the outer periphery of a transparent endless belt, and not only can static electricity removal and charging be performed on the outer periphery, but also light can be applied from the inside. If static electricity is removed by irradiation, it is possible to form an electrostatic latent image. For this reason, in this embodiment, the latent image writing head 3 and the head conveying means 12 are arranged inside the photoreceptor 1, thereby preventing the apparatus from increasing in size.

The scanning speed for forming this electrostatic latent image is 250 mm per second, which is the relative speed between the photoreceptor 1 and the latent image writing head 3, and even if a latent image writing head such as an LED array is used, the electrostatic latent image can be formed with sufficient contrast. Formation of latent images is possible. In addition, a belt-shaped photoreceptor 1
If there is a risk that slight variations in the distance between the latent image writing head 3 and the photoconductor 1 may occur due to the use of a What is necessary is to form an image on it.

The electrostatic latent image thus formed on the photoreceptor 1 is developed by a developing device 24 and transferred onto a copying paper 25 by a transfer device 26. The copy paper 25 is removed by a paper peeler 27
The photoreceptor is peeled off from the photoreceptor 1 and conveyed to a fixing device (not shown) or the like.

In this way, copying operations can be performed at high process speeds of 500 mm/sec.

"Modified Example" The copying apparatus of the present invention is not limited to the above embodiment.

For example, as for the latent image writing head, it is possible to use a head that forms an electrostatic latent image by irradiating the photoreceptor with an ion current according to an image signal. Further, if there is an installation space, the head conveyance means may be installed outside the photoreceptor conveyance path.

``Effects of the Invention'' According to the copying apparatus of the present invention described above, even if a latent image writing head with a relatively slow writing speed is used, a sufficiently high quality electrostatic latent image can be formed on the photoreceptor at a high process speed. Formation can be performed.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a copying apparatus according to the present invention, and FIG. 2 is a perspective view of main parts of a conventional copying apparatus. 1...Photoreceptor, 3...Latent image writing head, 1
1...Photoreceptor conveyance means, 12...Head conveyance means.

Claims (1)

[Scope of utility model registration request] a photoreceptor, a latent image writing head that forms an electrostatic latent image on the photoreceptor, and a photoreceptor conveyor that transports the photoreceptor in a predetermined direction at a predetermined speed to perform scanning for forming an electrostatic latent image. and a head conveyance means for conveying the latent image writing head in the same direction as the conveyance direction of the photoreceptor at a relative speed different from the conveyance speed thereof.