JPH0450960A - Electrostatic printer - Google Patents

Abstract

PURPOSE:To miniaturize a printer by performing copying in a state where the speed of a developing process and the speed of a transfer process are made different. CONSTITUTION:In the case of performing trial copying previous to printing, the speeds of the developing process and the transfer process are made different. Namely, when an unfixed process is formed by performing electrostatic charging, exposure and development to a photosensitive body 2, a speed switching means 100 switches the speed of a main motor 101 to a high speed side to make the speed of the photosensitive drum 2 nearly same as that of a fixing device 5. A paper feeding speed is also set the same speed so as to perform transfer at a high speed. As a result, the irregularity in an image is not caused, because a paper is not stretched even when a gap D between the drum 2 and the fixing device 5 is <= about 300 mm, for example, and even when the paper is laid between the drum 2 and the fixing device 5. Thus, the printer is miniaturized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electrostatic printing device having a test printing mode and a printing mode.

[Conventional technology]

A conventional electrostatic printing device will be described with reference to FIGS. 6 and 7.

As shown in FIG. 6, a photosensitive member 2, an exposure optical system 3, a paper feed mechanism 4, a fixing device 5, etc. are arranged within the electrostatic printing apparatus main body l. As shown in FIG. 7, the photosensitive member 2 is provided with a roll-shaped master 7 and a take-up roll 8 in the scroll drum 6, and the master 7 is inserted into the surface of the scroll drum 6 through a slit-shaped opening 9 of the scroll tram 6. The master 7 is wound on the scroll drum 6, and the master 7 is wound on the take-up roll 8 through the slit opening 9, and the master 7 is unwound by rotating the take-up roll 8, and a new master 7 is wound on the surface of the scroll drum 6. ing. Around this photosensitive member 2, a charging corotron 10, a static elimination lamp +1, a flash fixing device 12, a developing device 13, a transfer corotron 14, a paper peeling section 15, etc. are arranged in order, and the exposure optical system 3 includes a lamp 16, lens 17, mirror 18
The original image on the platen glass 19 is exposed to light onto a photosensitive member to form an electrostatic latent image.

The paper feeding mechanism 4 includes an upper tray 20 and a lower tray 21,
The paper is sent from one of these trays through the paper transport path 22 onto the photosensitive member 2, and the paper transport path 22
As shown in FIG. 7, a feed roll 23 is provided,
The paper 24 sent by this feed roll 23 is
It passes between the chute 25 and the second chute 26, and is sent between the photosensitive member 2 and the transfer corotron 14 via the upper chute 28 by the feed roll 27.

This paper is charged by corona discharge from the transfer corotron 14, and is electrostatically attracted to the surface of the photosensitive member 2.

The paper peeling unit 15 includes a peeling belt 15a, and the photosensitive member 2
Peel off the paper adsorbed to the surface of the paper conveyor belt 2.
9, and the sheet conveying belt 29 sends the sheet to the fixing device 5.

When performing a copying operation in an electrostatic printing device such as No. 2, the surface of the photosensitive member 2 is charged with a charging corotron 10, as in a normal electrophotographic copying machine, and then the exposure optical system 3 is used to transfer a document image. An electrostatic latent image is formed by irradiation exposure, and this electrostatic latent image is developed with toner by a developing device 13, and then the toner image is transferred to a paper 24 by a transfer corotron 14, and the paper 24 is sent to a fixing device 5 to be fixed. After that, the paper is discharged to the paper tray 30.

In the print mode, the toner image formed as described above is flash-fixed by the flash fixing device 12, and the toner image is fixed on the photosensitive member to form a print master, and then the print master is charged with an electrostatic corotron. Then, the entire surface is exposed with a static elimination lamp 11, leaving only the toner image part charged, and the developing machine 13 develops it again to form an unfixed toner image.
This unfixed toner image is transferred to the paper 24 using the transfer corotron I4.
After the paper 24 is transferred to the fixing device 5, the paper 24 is transferred to the fixing device 5 and fixed. Thereafter, by repeating this operation, a large number of copies can be obtained using the toner image as a print master.

[Invention or problem to be solved]

By the way, in conventional electrostatic printing devices, the process speed (drum circumferential speed) is, for example, 150 mm/sec to move the optical system in the copy mode, and 437 mm/sec, for example, in the print mode. The speed of the fixing device is approximately the same as the process speed in the print mode, for example, 440 mm/sec. In addition, in the flash fixing process of the plate making process, the toner image is sequentially fixed in a fixed width, so at that time, 23w
n/secC.

In this way, in copy mode, the process speed is
Since the speed is as slow as 50 mm/see, if the leading edge of the paper reaches the fuser while the paper is still wrapped around the drum, the paper will be pulled by the fuser and the paper will rub against the drum, resulting in the image being distorted. Therefore, as shown in FIG. 6, the gap between the fixing device and the drum is made larger than the maximum paper size to prevent the paper from being pulled by the fixing device. As a result, the size of the device becomes extremely large, causing problems such as the fact that the device cannot be accommodated in a narrow elevator or the like. In addition, before printing, a test print may be performed to check whether the original position and magnification are set correctly, but if you are not satisfied with the test print after creating the plate-making master, the master There was a problem in that the master had to be rolled up, wasting the master, and in addition, when creating the master plate, there was a problem in that it took a very long time to perform flash fixing. Furthermore, if the result of the preparation is unsatisfactory, operations such as winding up the plate-making master must be performed, resulting in poor operability.

The present invention is intended to solve the above-mentioned problems, and in addition to downsizing the device, it saves on the master making plate for trial printing, and it is also possible to perform only high-quality trial printing, thereby reducing time and improving operability. An object of the present invention is to provide an electrostatic printing device that can achieve the following.

[Means and effects for solving the problem] The present invention provides an electrostatic printing device in which a copy mode and a print mode can be selected, and copies are made by changing the speeds of the development process and the transfer process (hereinafter referred to as trial printing). In the test printing mode, after creating an unfixed plate image by charging, exposing, and developing, the speed of the main motor is changed to match the speed of the fuser. Combine,
It is designed to transfer and fix images by rotating the drum and feeding the paper at high speed. In this way, in the test printing mode, by making the speeds of the development process and the transfer process different, it is possible to prevent image distortion even if the distance between the drum and the fixing device is shortened, making the device more compact. I can do something. In addition, if you are not satisfied with the result, you can use the same photosensitive material to make a test print with the unfixed plate making state, so there is no need to wind up the photosensitive material, which saves on the master. At the same time,
It is possible to improve operability.

Furthermore, since there is no need to perform flash fixing, time can be shortened, and test printing can be performed as many times as desired without winding up the master.

〔Example〕

Examples will be described below with reference to the drawings.

FIG. 1 is a diagram for explaining the present invention in detail, FIG. 2 is a diagram for explaining the features of the electrostatic printing apparatus of the present invention, and FIG. 3 is a diagram showing a test printing sequence. In the figure, 100 is a speed period changing means, and 101 is a main motor.

In the present invention, when trial copying is performed prior to printing, the speeds of the development process and the transfer process are made different. That is, when an unfixed plate is created by charging, exposing and developing the photoreceptor, the speed period changing means 100 shown in FIG. 1(a) changes the speed of the main motor 101 as shown in FIG. 1(b). The speed is switched to the high speed side to make the photosensitive drum speed almost the same as that of the fixing device, and the paper conveyance speed is also set to the same speed to perform high speed transfer. As a result, as shown in FIG.
Even if it is less than 0 mm, the speed of the drum and fuser will be the same, so even if the paper straddles the gap between the drum and fuser, the paper will not be pulled and the image will not be distorted. , the fruiting device can be downsized.

FIG. 3 is a diagram showing the sequence of speed switching according to the present invention, in which the horizontal axis represents the number of drum rotations (clock count value).

To explain the outline of the sequence, first, when the switch is turned on, the main motor rotates, and at the home position, the exposure lamp, IS [, (lamp for erasing unnecessary image areas)]
, the developing bias, and the developing motor are turned on. Then, at the specified timing, charge corotron (CC) is turned on.
At the same time, the carriage motor or O
N, the optical system is driven, and exposure is performed. The figure shows the timings of the exposure lamp, fixing lamp, carriage motor, transfer corotron (TC), and -corotron (EC) depending on the paper size. When the development is completed, the development motor is reversely rotated to eliminate spikes of toner and prevent the unfixed toner image from being disturbed. Then, at the same time as the developing machine is turned off, the speed of the main motor is changed from 150 fps/sec to a high speed of 437 f/sec to match almost the same speed as the fixing device. Then, the registration roll is turned ON to feed the paper at a timing such that the paper is aligned with the leading edge of the toner image, and the TC is turned ON at the same time as the paper to perform transfer.

After the transfer is completed, the main motor is switched to 150 mm/sec, the EC is turned on to make it easier to remove the toner remaining on the photoreceptor, and the developing motor is rotated to scrape off the toner with its spikes to perform cleaning.

In this case, by turning on the erase lamp, the potential of the photoreceptor is set to approximately 0, and the developing bias is increased to attract the toner, thereby making it easier to scrape off the toner.

By the way, in such a test printing mode, the transfer process speed can be increased from 150 mm/sec to 437 mm/sec.
When the speed is changed to mm/see, the transfer efficiency (the ratio of the amount of transferred toner to the total amount of toner used for development) inevitably decreases, and the image quality deteriorates due to insufficient density.

Therefore, as shown in Figure 4, by providing a Bri Transfer Corotron (PTC) +03 to lower the potential of the toner image before transfer, it is possible to increase the transfer efficiency, and as a result, the image quality is poor due to insufficient density. Deterioration can be prevented. Note that installing a PTC will increase costs, so the PTC function can be implemented using the existing charge-eliminating corotron (EC) 104 installed in the existing charging device 10, and the image potential can be set using the ONL after unfixed plate making is completed. A similar effect can be obtained by lowering the amount and then turning on TCI4 to perform transcription. However, when using EC, it is necessary to rotate the drum an additional rotation.

FIG. 5 is a diagram showing the relationship between EC current value and transfer efficiency.
It can be seen that a transfer efficiency of 80% or more can be obtained by setting the EC current value to an appropriate value.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to downsize the device, save on masters, shorten the time for test printing, improve operability, and improve transfer efficiency by using PTC or EC. It is also possible to improve the image quality by increasing the

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the present invention in detail, FIG. 2 is a diagram for explaining the features of the electrostatic printing apparatus of the present invention, FIG. 3 is a diagram for explaining the test printing sequence, and FIG. FIG. 4 is a diagram showing another embodiment of the present invention, FIG. 5 is a diagram showing the relationship between the current value of the static eliminating corotron and transfer efficiency, and FIGS.
The figure shows a conventional electrostatic printing device. 100...Speed period changing means, 101 is a main motor. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Masanobu Hirukawa (7 others) Figure 1 Figure 2 Private copy ('/,)

Claims (2)

[Claims] (1) A test printing mode in which an unfixed plate-making master created by charging, exposing, and developing a photoreceptor that is wound in a roll inside a scroll drum and fed out along the outer circumferential surface of the drum is transferred and fixed; This is an electrostatic printing device that can select a printing mode in which a plate-making master created by charging, exposing, developing, transferring, and fixing a master plate created by charging, exposing, developing, and then flash-fixing the plate, and in which it is possible to perform development in the trial printing mode. An electrostatic printing device characterized in that a process speed and a transfer process speed of an unfixed plate-making master are made different. (2) The electrostatic printing apparatus according to claim 1, wherein the pre-transfer image potential of the unfixed plate-making master is lowered by a pre-transfer corotron or a static elimination corotron.