JPS582866A - Discharging method for recording body - Google Patents

Abstract

PURPOSE:To obtain a small-sized, lightweight discharger by selectively discharging only the charging part of a recording body which has an uneven surface by bringing a discharging electrode member into contact with the surface of the recording body. CONSTITUTION:Over the entire surface of a recording body belt 1, fine unevenness with about 10mum depth is provided, and consequently when a discharging electrode roller 19 is brought into contact with the surface of the recording body, a fine space is formed between this roller 19 and the recording body surface to allow discharging. A pulse voltage appied to the roller 19 has the opposite polarity to a voltage applied to a stylus electrode 9. Then, the sum of the potential of a dot charging part on the belt 1 and this applied voltage is higher than the voltage of a Paschen's law discharge starting voltage curve shown in the figure, and the sum of the potential of an uncharged part on the belt 1 and the applied voltage is lower than the discharge starting voltage. Further, the pulse width of the applied pulse voltage is less than the value obtained by dividing the contact width between the roller 19 and recording body surface by the linear moving speed on the recording body surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for eliminating charge from a recording medium in an electrostatic recording apparatus.

An electrostatic latent image is created on the surface of a recording medium having a dielectric surface by discharge of a needle electrode to which an image signal voltage is applied, and this is developed with colored fine particles called toner, and the developed image is transferred to transfer paper to form an image. A recording device that obtains the following is known.

In order to be able to repeat images, the toner and charge remaining on the recording medium must be removed each time recording is performed.

One of the conventionally known recording medium neutralization methods is the AC corona method. In this method, an AC high voltage is applied to the corona charger to irradiate the surface of the recording medium with AC corona, but since the bipolar corona is discharged, it takes a long time to decay, and the environment such as humidity etc. Since the positive and negative discharge efficiencies differ, it is necessary to balance the positive and negative discharge currents. Another method is the direct current corona method. This generates a DC corona component by connecting a DC high-voltage power supply to the corona charger, but because the on/off response is slow, overshoot tends to be large, making it difficult to control the static electricity removal convergence set value. There are drawbacks. These corona methods cannot selectively remove charges from charged and non-charged areas on the recording medium, that is, eliminate charges only from the charged areas, so even if the average potential on the surface of the recording medium can be lowered, It is not possible to erase the potential difference with the uncharged part. Yet another static elimination method is a polar solvent coating method. This method removes static electricity by applying a polar neutralized solvent to the surface of the recording medium, but it requires supply and control of the solvent, drying of the solvent, etc., and has the drawback of increasing the size of the apparatus. There are also problems with the surface shape of the recording medium, such as the wetting characteristics between the surface of the recording medium and the solvent, and various other problems such as dust adsorption and water condensation.

The purpose of this invention is to perform two steps to eliminate static electricity from an electrostatic recording medium:
The static eliminator is small and lightweight, selectively neutralizes the charged and non-charged parts of the recording medium, accurately converges the surface potential of the recording medium to zero potential or a predetermined potential, and eliminates electrical, physical, and chemical stress. It is an object of the present invention to provide a method for eliminating static electricity from a recording medium, which can eliminate static electricity from a recording medium so as to prevent the generation of static electricity.

The static electricity removal method according to the present invention is particularly effective in micro-generally covering the entire surface.
In forming a latent image by discharging a needle electrode, an accurate discharge gap must be maintained between the needle electrode and the surface of the recording medium. In order to cause discharge, a voltage higher than Paschen's discharge starting voltage curve is applied to the needle electrode.
If the discharge gap is too small, the discharge starting voltage will rise rapidly, and if the discharge gap is too large, the resolution will not only deteriorate, but also the discharge starting voltage will rise. It is extremely difficult to accurately manage such a discharge gap to the μm order, so by creating irregularities with a depth of around 10 μm on the surface of the recording medium and bringing the needle electrode into contact with this irregular surface, the discharge void can be easily controlled. Moreover, it is easily and stably obtained.

The charge removal method according to the present invention uses a process similar to the latent image forming process for a recording medium having such an uneven surface to selectively remove charge only from a charged portion, or to slightly reverse the charge to the opposite polarity side. It is characterized by. That is, a static elimination electrode member is brought into contact with the surface of the recording medium, a discharge gap is obtained by the contact surface of the static elimination electrode member and the unevenness of the recording medium surface, and the static elimination applied to the charging line potential on the recording medium surface and the static elimination electrode member is The pulse width of the static elimination pulse voltage is set so that the sum with the pulse voltage exceeds the discharge starting voltage.
The width of contact of the static elimination electrode member with the surface of the recording medium is determined to be an integer fraction of the value obtained by dividing the linear velocity of movement of the surface of the recording medium,
As a result, the main feature is that the charged portion on the surface of the recording medium is selectively reversed slightly to the neutralizing portion or to the opposite polarity side. Limiting the time of the pulse voltage applied to the static elimination electrode member is important because if the pulse width is too large, not only will the discharge efficiency decrease,
In addition, when static electricity is removed using a pulse voltage, the overshoot of the discharge is small and there is no large swing to the opposite charge, and the potential after static electricity removal is Large to convergence point? It does not cause any variation.

The present invention will be described below with reference to the accompanying drawings. FIG. 1 schematically shows an example of an electrostatic recording device to which the static elimination method according to the present invention is applied.

The recording medium 1 is formed in the shape of an endless belt: fine irregularities with a depth of about 15 μm are formed on its entire surface. The recording belt 1 is supported by a support roller 2.5,
Driven in a counterclockwise direction. A recording section 4, a developing section 5, a transfer section 6, an IJ-ning section 7, and a static eliminating section 8 are arranged around the recording belt 10 along the rotational direction from the top thereof.

The recording section 4 includes a multi-needle electrode 9 disposed with its tip end in contact with the surface of the recording belt 10. The developer section 5 includes a rotatable non-magnetic sleeve 11 for holding a magnetic toner 10 on its surface, and a magnet stationary therein. The rolling unit 6 includes a conveyance roller 15 for bringing the transfer paper 12 into contact with the belt 1, and a transfer corona charger 14.
, a separated phase corona charger 15 , and a conductive separation belt 16 .

The cleaning section 7 includes a fur brush 17 rotatably disposed in contact with the surface of the belt 1, and an elastic rubber roller 18 rotatably disposed in contact with the back surface of the belt 1 opposite to the fur brush 17. including. The static eliminator 8 includes a static eliminator electrode roller 19 that is rotatably provided in contact with the front surface of the belt 1, and an elastic rubber roller 20 that is rotatably provided in contact with the back surface of the belt 1 opposite thereto. .

First, the surface of the recording belt 1 is connected to the signal controller 2.
The needle electrode 9 is selectively charged by the needle electrode 9 which is connected to 1K and applied with a dot-divided negative image signal voltage, and a dot-divided electrostatic latent image is formed thereon. This negative electrostatic latent image is made visible by being supplied with positively charged toner 1o from the developing section 5, and then this developed image is applied to the transfer paper 1o.
2 are stacked on top of each other, and the transfer corona charger 1 is placed from behind.
The developed image is transferred to the transfer paper 12 by being positively charged by 4Vc. The transfer paper 12 after the transfer is separated from the surface of the recording medium by the separating corona charger 15 and the separation belt 16, and the toner remaining on the surface of the recording medium belt 1 is removed by the cleaning 7 arbrush 17, and the remaining charge is removed by pulse The static electricity is removed by the static elimination electrode roller 19 to which a static elimination pulse voltage is applied from the generator 22 .

In this invention, the entire surface of the recording belt 1 is provided with four minute convexities, so a minute space is created between the recording static elimination electrode roller and the recording body surface, which enables discharge. It becomes a gap.

The pulse voltage applied to the static elimination electrode roller 19 has the opposite polarity to the voltage applied to the needle electrode 9, and the sum of the potential of the dot-charged portion on the belt 1 and this applied potential is the same as that of the static elimination electrode roller 19. The voltage between the belt 1 and the Paschen discharge starting voltage curve as shown in FIG. In addition, the pulse width of the applied pulse voltage is set to be smaller than the pupil obtained by dividing the contact width between the static elimination electrode roller and the surface of the recording medium by the linear velocity of movement of the surface of the recording medium. As a result, a discharge is generated mainly only to the dot-charged portions on the belt in a manner that cancels out the electric charge thereon, and is not discharged to the uncharged portions. By reducing the potential difference between the charged part and the uncharged part without applying physical stress, the charge on the surface of the recording medium can be efficiently removed.

In an actual static eliminator, the static eliminator electrode roller 19 has a diameter of 2011 II and a wall thickness of 1.5 mm. ! Using a stainless steel vibrator with a precision-finished surface, this has a VC of 600μ.
A rectangular pulse voltage with a pulse width of s and a peak voltage of +400 V was applied. Further, an elastic rubber roller 20 disposed opposite to this static elimination electrode roller 19 has a diameter of 40 mm.
- Use a rubber hardness of A65, which is 1009
It was pressed against the recording belt 1 at a pressure of 7 cd.

The recording belt 1, the static elimination electrode roller 19, and the elastic rubber roller 20 were each driven in the same direction at the same linear speed of 10011 sh'S. FIG. 5 shows the transition of the recording medium surface potential in each process when such a static eliminator is applied to the electrostatic recording apparatus shown in FIG. 1 to perform recording. As is clear from this solidification, the effect of the static elimination method based on the trap of this invention is remarkable, and even if the potential of the charged part of the recording medium after transfer is about 1,220 V, after static elimination, this is suppressed to within the range of +10 V to +50 V. be able to.

The static elimination method according to the present invention can be applied to other types of electrostatic recording devices, and all changes within the spirit of the present invention as described in the claims are included in the present invention. .

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an electrostatic recording device to which the static elimination method according to the present invention is applied, and FIG. 2 is a typical Paschen curve (solid line) and typical air gap voltage versus air gap for two Mylar sheets. 5 is a graph showing the width curve (broken line), and the numerical value in the graph shows the sum of the applied voltage and the voltage of the surface charge. FIG. 5 is an image showing the effect of one embodiment of the present invention. FIG. 3 is a diagram showing the transition of the recording medium surface potential during the formation process.

Claims (1)

[Claims] A method for eliminating static electricity from the surface of a recording medium in which a predetermined charge pattern is formed by discharge of a needle electrode and having minute irregularities over the entire surface of the recording medium, the method comprising: bringing a static elimination electrode member into contact with the surface of the recording medium; A discharge gap is obtained by the electrode member and the unevenness on the surface of the recording medium, and the sum of the potential of the charged part on the surface of the recording medium and the static elimination pulse voltage applied to the static elimination electrode member exceeds the discharge starting voltage. and the pulse width of the static elimination pulse voltage is set to one integer of the value obtained by dividing the contact width of the static elimination electrode member with the surface of the recording medium by the linear velocity of movement of the surface of the recording medium. 1. A method for neutralizing static electricity from a recording medium, characterized in that a voltage is determined, thereby selectively neutralizing primarily charged portions on the surface of the recording medium.