JPS6332385B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printing device that applies the principle of electrophotographic copying, that is, an electronic printing device, and particularly to a cleaning and developing device.

Printing by electrophotography has been known for a long time. For example, the zero printing method in U.S. Patent No. 2,576,047, or the
43-1554 electronic printing device, etc. This involves forming a powder image on a photoconductive plate and fusing or fixing it by an electrostatographic method to form a non-photosensitive insulating image figure, that is, a printing master, on the photoconductive plate.
Next, this printing master is uniformly charged and further uniformly irradiated with light. Thereby, the charged powder is deposited on the partially charged plate to form a powder image, since the charge is retained only on the non-photosensitive image areas and discharged on the photosensitive areas. The above steps are repeated by transferring onto a suitable image support.

In particular, Japanese Patent Publication No. 43-1554 shows a device as shown in FIG. In FIG. 1, reference numeral 1 denotes a rotating drum, which has retaining claws on its circumferential surface so as to support the photosensitive paper 10.

A cleaning device 8, a charger 4, a uniform exposure lamp 13, a developing device 5, a transfer corotron 6, an infrared fixing device 7 for fixing the toner image on the photosensitive paper 10, etc. are installed surrounding the rotating drum 1. has been done.

To create a print master, after the photosensitive paper 10 is wrapped around the rotating drum 1 and supported, it is charged by the charger 4, and then the document on the document table 3, which is illuminated by the document illumination lamp 14, is exposed through the projection lens 2. photosensitive paper 1
0 to form an electrostatic latent image. Next, the latent image is visualized by a developing device 5, and the toner image is fused and fixed onto photosensitive paper 10 by an infrared fixing device 7, thereby forming a printing master. Ru.

Electrostatic printing of a large number of sheets using the printing master described above is performed in the following manner. A printing master having a toner image on photosensitive paper is charged by a charger 4, and further exposed uniformly over the entire surface by a uniform exposure lamp 13. The charge on the uniformly charged photosensitive paper 10 is washed away by uniform exposure, leaving only the toner image portion of the insensitive and non-photoconductive plate. Therefore, a printing master is formed in which only the toner image portion has an electric charge, and the developing machine 5
It is visualized by. Next, the transfer paper 11 is sent to the transfer section in synchronization with the rotation of the rotary drum 1, and the toner image on the print master is transferred to the transfer paper by the transfer corotron 6, and then becomes a fixed image by the fixing device 9. , and are guided to the paper output tray to obtain copies. On the other hand, the residual toner on the print master after transfer is cleaned by the cleaning device 8, and one printing cycle is completed. after that,
The printing cycle is repeated for as many copies as required.

However, since such electrostatic printing machines make a large number of copies, a large amount of used toner accumulates in the cleaning device that removes residual toner from the print master. Maintenance inspections such as eruption are required. In other conventional techniques, there is a method of providing a cleaning function to the developing machine to eliminate the need for a dedicated cleaning device. When using such a conventional cleaning/developing device, the rotating drum is rotated twice in order to take one copy, and developing and cleaning are performed alternately.
Alternatively, the bias voltage applied to the developing device has been changed between developing and cleaning.

However, this method has disadvantages, such as the need for a complicated apparatus and the fact that only one copy can be obtained in two revolutions, making it unsuitable for high-speed copying.

An object of the present invention is to provide a developing device having the effect of cleaning residual toner on a printing master,
1 revolution, eliminating the need for dedicated cleaning equipment
The object of the present invention is to provide a printing device that can obtain copies, and the present invention is characterized by the fact that the developer on the developing roller of the developing machine has a contact width of 5 mm or more with the photoconductive plate carrying the electrostatic image. It is characterized in that it produces a cleaning effect.

The toner charging state of the photoconductive plate in the present invention will be explained in detail with reference to FIG.

In FIG. 2, a printing master 15 is a toner image 1 fixed to a photoconductive layer 102 on a support 101.
03, and shows the state after charging and uniform exposure. In this figure, since a negatively charged photoconductive plate 10 is used, the fixed toner image 103 is similarly charged negatively. Next, FIG. 2 shows how the fixed toner image 103 is developed by the developing roller 16 carrying positively charged toner.

Next, FIG. 2 shows the transfer of the toner image 17 onto the transfer paper 11 using the transfer corotron 6 and the charging of the next cycle by the charger 4.

Due to the negative charging by the transfer corotron 6 and charger 4, the charged polarity of the residual toner image 18 on the print master changes from positive to negative, and the adhesion of the residual toner image to the print master is weakened.

Next, FIG. 2 shows the state after uniform exposure by the uniform exposure lamp 13 in the next cycle.

Next, FIG. 25 shows the next cycle of development.

The residual toner 18 whose adhesion has weakened due to the process shown in FIG. 2 and 3 is easily removed by the developer ear of the developing roller 16 at the front end of the ear, and new toner of positive polarity is reattached on the rear side. .

In this way, the residual toner image 18 and the new toner image 19
By replacing this, it becomes possible to eliminate the dedicated cleaning device. An embodiment of the present invention will be described below with reference to FIG.

First, to explain how to create a print master,
Insert the photosensitive plate through the insertion slot 29, and press the photosensitive plate support claw 31.
It is also supported on the rotating drum 20. Next, the charger 21 charges the document and exposes the image of the document on the document table 24 to form an electrostatic image on the photosensitive plate. Next, the photosensitive plate is visualized by a developing device 26 , and the photosensitive plate is once peeled off from the rotating drum using a peeling device 28 , and further passed through a pressure fixing device 32 and discharged from a photosensitive plate discharge roller 33 . In this way, a printing master is formed having a toner image fixed on the photosensitive plate.

Next, the print cycle will be explained.

The created print master is passed through the insertion slot 29, and is again wrapped around the rotating drum 20 to support it. Next, the charger 21 is used to charge the print master, and the entire surface is exposed using the uniform exposure lamp 25. After forming the electric image, it is visualized by a developing device 26. Next, transfer the corotron 2 onto the transfer paper 35.
7 and further fixed to obtain a copy.

With this, the first printing cycle ends.

In the second printing cycle, charging is performed by a charger 21, the entire surface is exposed by a uniform exposure lamp 25, and the image is visualized by a developing device 26. At this time, residual toner from the first printing remains on the printing master, but the residual toner is removed and new toner is repositioned by a developing roller that has a contact width of 5 mm or more between the developer and the printing master. A second toner image is formed on the print master. Next, the image is transferred onto the transfer device 35 and fixed, thereby completing the second printing cycle. This printing cycle is repeated repeatedly until the required number of copies are printed.

In the above, in order to achieve a contact width of 5 mm, there are methods such as increasing the diameter of the developing roll, increasing the magnetic force to make the magnetic brush ears higher, or bringing the developing roll and photoreceptor closer together. It may be carried out by one or a combination of these.

A comparative example between the present application and the conventional method is shown below.

In a conventional method in which the cleaning device was simply removed, development was performed with a developing contact width of 3 mm, but the trailing edge portion of the image was blurred and the cleaning effect was poor. Next, when I raised the bristles of the brush to a contact width of 5 mm, the edges did not become blurred and the cleaning effect was achieved. It was found that the effect of replacing old and new toner is not effective unless the developer on the developing roller contacts the printing master 15 with a width of 5 mm or more. Furthermore, the volume resistance of the developer used in the developing machine of the present invention is 1×10 ¹³ Ω·cm or less to increase the efficiency of removing residual toner. Furthermore, if the printing toner gets into the minute recesses of the light guide layer 102 and the fixed toner 103, it becomes difficult to remove the residual toner 18, so a pressure fixing device is used as a toner fixing method when creating a printing master. photoconductive layer 1
It has been found that by improving the surface smoothness of 02 and fixed toner 103, the effect of replacing old and new toner can be promoted.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an electronic printing apparatus, FIG. , 1... Rotating drum, 2... Projection lens,
3... Document table, 4... Charger, 5... Developer, 6... Transfer corotron, 7... Infrared fixing device, 8... Cleaning device, 9... Fixing device, 10... Photoconductive plate, 11...
Transfer paper, 12... Paper discharge tray, 13... Uniform exposure lamp, 14... Original illumination lamp, 15... Print master, 16... Developing roller, 17... Printing toner, 1
8...Residual toner image, 19...New toner, 20...
Rotating drum, 21... Charging corotron, 22... Image exposure lens, 23... Illumination lamp, 24... Document table, 2
5... Uniform exposure lamp, 26... Developing machine, 27... Transfer corotron, 28... Peeling device, 29... Photosensitive plate insertion slot, 30... Register roller, 31... Photosensitive plate support claw, 32... Pressure fixing device, 33... Discharge roller,
101...Support, 102...Photoconductive layer, 103...Fixed toner image.

Claims (1)

[Scope of Claims] 1. A one-rotation, one-copy type cleaning and developing device, characterized in that the contact width between the developer on the developing roller and the printing master carrying an electrostatic image is 5 mm or more. 2. The developing device according to claim 1, wherein the developer has an electrical resistivity of 1×10 ¹³ Ω·cm or less, and is a one-rotation, one-copying, cleaning-combined developing device.