JPS59147374A - Brush cleaning method of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent toner from falling on a photosensitive body during the stop of a copying machine by applying an AC voltage to one flicker bar and grounding the other flicker bar right before the supply of a DC voltage is stopped, and stopping the passage of toner containing air. CONSTITUTION:When the copying machine is stopped, the AC high voltage is applied to one flicker bar, e.g. downstream-side flicker bar 6' and the other upstream-side flicker bar 6 is grounded for about 1-2sec right before the supply of the DC voltage to both flicker bars 6 and 6' is stopped. During this period, AC corona discharge is caused between the flicker bars 6 and 6'. Bipolar internal electrostatic charge is neutralized by recombination with corona ions through the irradiation of the corona discharge. Therefore, a toner layer sticking to and deposited on an suction port 7 between the flicker bars 6 and 6' increases in collapsing or sticking force greatly to scatter toner as cloud, and it is conveyed toward a duct 9, so that the toner is prevented from falling on a photosensitive body.

Description

DETAILED DESCRIPTION OF THE INVENTION In the present invention, two fur brush rolls are used, and a pair of 7-flick covers are in contact with each of the two fur brush rolls, and the fur brush The present invention relates to a brush cleaning method for an electrophotographic copying machine in which a toner cloud scattered by the wiping action of a roll is sucked by a vacuum cleaner.

In the brush cleaning method described above, DC braking voltages with different polarities are constantly applied to the two flicker covers while the copying machine is in operation, so the charged toner particles passing between the flicker covers are applied to the flicker covers by Coulomb force. Easy to adhere.

The air flow path between the two 7-litre bars has a width of 25 to 3 u and is shaped like a slit over almost the entire length of the cleaning device (400 as), and the wind speed inside the slit is approximately 5 m/sec.
It is c.

When a voltage is applied to the flicker bar, the toner charged on the glass is attracted to the flicker bar to which a negative voltage is applied, and the negatively charged toner is attracted to the 01lli+ of the other seven covers by Coulomb force. In this case, a wind speed of 5 ml/sec does not prevent toner from adhering to the toner and deposits S, and once the toner adheres, the strength of the adhesion increases with the passage of time.

- If the applied voltage to the flicker bar is stopped, the adhesion of the accumulated toner due to Coulomb force will weaken, so if the copying machine is stopped with toner still attached to the flicker bar, when the copying machine is stopped, This adhered toner falls onto the photoreceptor due to the movement of the photoreceptor, resulting in smearing of the image quality.

Unexploded uA was developed to improve the drawbacks of the conventional method described above, and it allows the toner layered and accumulated on the flicker bar to collapse and be sucked out before the copying machine is stopped, especially before the vacuum source is stopped. To provide a reliable tubular brush cleaning method which can prevent toner from falling from a flicker bar when the machine is stopped and which does not adversely affect image quality.

Embodiments of the present invention will be described below based on the drawings.

The image bearing member 1 is constructed in the form of a belt and is made of an N-type optical fiber conductor, and this image bearing member is formed by applying -8- to the T/Shimin rolls 2, 2' and the Hiflaten roll 313'. 4,4
′ is a pair of fur brush rolls that are in contact with the image carrier 1 and whose rotating shafts are perpendicular to the moving direction of the image carrier 1. It is made up of approximately 2,000 synthetic fibers implanted on the outer surface, and rotates at approximately 12,007'pm. Note that the rotation directions are opposite to each other, and the image carrier 1
Fur brush roll 4 or image carrier 1 on the upstream side in the moving direction of
The fur brush rolls 4' on the downstream side are rotated so as to perform a wiping action in the same direction as the fur brush rolls 4' on the downstream side. 5 is fur brush roll 4,
A housing 6 and 6' cover the fur brush rolls 4 and 4', and metal housings 6 and 6' have the function of brushing off toner particles adhering to the brush fibers of the fur brush rolls 4 and 4' and imparting a desired polar charge to the brush fibers. It's Ritsukaba. This flicker bar 6.6' is fixed to the housing 5, and a suction lower opening into the housing 5 is provided between the two flicker bars 6.6'. This suction 07 is connected to a duct 9 via a flow path 8. This duct 9
It is connected to a dust collector having a vacuum source through a hose (both not shown). Electric field tone, I + , + +'
is an orifice baffle which forms a slit through which air flows quickly between the image bearing member 1 and both ends of the housing 5 and prevents toner particles within the housing 5 from leaking out of the cleaning device. 12 is a pre-cleaning corotron consisting of a cleaner corotron wire 13 and a corotron shield 14.
4CrO irradiation of 23An-eec/cyd and 0.04
Glass DC corona irradiation is performed at 6 μA-, r t C/cd, so that the residual toner image on the image carrier 1 is processed to be easily cleaned. Of the pair of seven-point flicker covers 6 and 6', the upstream flicker 6, which contacts the fur brush roll 4 located upstream in the moving direction of the image carrier 1, has a minus 3 KV power applied to the downstream. A direct current/voltage of 3 KV is applied to each of the seven power covers 6' according to one rule. Note that the polarity of the applied current is reversed when the image carrier 1 is a PNN calf conductor.

In the above cleaning device, the untransferred toner image remaining on the image carrier 1 is removed by the pre-cleaning corotron 12.
After being processed to be more easily cleaned by receiving corona irradiation, the untransferred toner image is removed in the cleaning device by the wiping action and electric suction of the rotating fur brush rolls 4, 4', that is, by the pre-cleaning roller. Toner charged on the glass by the tron 12 is removed by the negatively charged upstream fur brush roll 6, and toner of opposite polarity that is not removed by the upstream fur brush roll 6 is cleaned by the glass. The fur brush roll 6' on the downstream side is electrically charged. The removed toner is then scattered into the air, passes through the suction lower in the vacuum source, flow path 8, duct 9, and hose, and reaches the Tojin device (not shown), where the toner and air are separated. . At this time, since a voltage is applied to the flicker bar 6.6', toner is adhered and deposited on both side walls of the suction lower 0 mainly due to Coulomb force.

Therefore, in the present invention, when the copying machine is stopped, an AC high voltage is applied to the flicker bar 6' on the downstream side, for example, 1 u before the voltage supply to both flicker bars 6 and 6' is stopped. , and on the other hand, for example, the upstream side cover 6
The ground contact period is approximately 1 to 2 seconds. The voltage supply time chart to the flicker bar 6.6' is shown in Figure 2, and the timing to stop the voltage supply to the flicker bar 6.6' is the same as the time when the power supply to the suction source (prower) is stopped. precede or coincide with the time.

Now, during the period when the 7-piece cover 6 on the upstream side is grounded and the 7-piece cover 6' on the downstream side is applied with the AC amount' city pressure,
An alternating current corona discharge occurs between the flicker bars 6 and 6'. In general, the causes of powder adhesion to objects such as other metals, or of powders adhering to each other, are (1) Coulomb force, (2) Van der Waals force, (31 surface tension,
(4) Although there are chemical bonding forces and the like, it is thought that the cause of toner particles adhering and accumulating between the flicker bars 6 and 6' is due to the above-mentioned cause +I+. In particular, when toner particles are locally charged with positive and negative charges and the particles are bonded together by Coulomb force, this is generally referred to as bipolar internal charging.

This bipolar internal charge is neutralized by angular bonding with corona ions by irradiation with alternating current corona discharge.

Therefore, the layer of toner adhering to and accumulating on the suction lower of the 7 Ritz Cover 6.6' curve will collapse or the adhesion force will be significantly reduced.
The toner forms a cloud and scatters.

Here, the bipolar internal charge amount will be specifically explained.

The bipolar internal charge breakdown of the toner is measured using the measuring device shown in FIG. The measuring device places the toner 20 between two flat electrodes facing each other, covered with dielectric layers 15α and 16α, and arranged at a distance of t, at an angle of +5°16.
An alternating current power source 17 is connected between each of the flat plate electrodes 15 and 16 through a protective resistor 18, and when the alternating voltage is gradually increased from this state, the toner 20 becomes cloud-like at a certain electric field strength. scatter. Police box P11 at this time. Measure the voltage and frequency of source 17. Further, if the frequency at this time is plotted on the horizontal axis and the scattered electric field strength is plotted on the vertical axis, a characteristic curve A shown in the fifth factor is obtained.

From the above, by applying a convection current 1' (71 voltage) to both flicker bars 6.6' and grounding the other, and applying AC corona discharge to both flicker bars 6.6', both flicker It can be seen that the single layer of toner adhering between bars 6 and 6' scatters in a cloud shape.At the time when this condition occurs, the vacuum source (blower) is still operating, and the wind pressure of the air flowing through the suction lower The toner that has been collapsed or whose adhesion force has been reduced due to the force is conveyed in the direction of the duct 9.

If the suction lower between both flicker bars 6.6' is narrow, spark discharge is likely to occur at both flicker bars 6.6', and since the electric field strength at flicker bar 6.6' is small, the coulombs acting on the toner are small. The force also increases the adhesion and deposition of toner. Therefore, as shown in Figure 3, the width of the suction lower is 2.
The above two problems can be solved by keeping the distance between 5 and 3 U and providing insulators t=+q, +q' at the slit opposing parts of both flicker bars 6,6'.

Since the present invention is as described above, the toner that adheres and accumulates between the covers 6 and 6' during operation of the copying machine collapses or scatters due to the weakening of the toner immediately before the copying machine is stopped.
This toner is transported in the direction of the duct 9, thereby preventing the toner from falling onto the photoreceptor while the copying machine is stopped. As a result, it is possible to obtain a fur brush cleaning method that is reliable for pots and has no problems with image quality.

In the present invention, the same effect can be obtained by applying a high voltage with a low frequency pulse such as a rectangular wave or a triangular wave instead of the AC high voltage applied to one of the seven covers.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a cleaning/cleaning device to which the present invention is applied, Fig. 2 is a timing chart, Fig. 3 is a sectional view showing a modified example of a flicker bar, and Fig. 4 is an internal charging of powder. Fig. 5 is a diagram showing the frequency of the internal charge of the powder and the intensity of the scattered electric field. 4.4' is a fur brush roll, 6 and 6' are flicker bars. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Masaaki Yonehara Patent Attorney Tadashi Hamamoto Figure 1

Claims (1)

[Claims] An electrophotographic copying device in which toner-containing air is allowed to pass between a pair of flicker bars 6 and 6' which interfere with the fur brush rolls 4 and 4' and to which direct ηL high voltages of mutually different polarities are applied. In the machine's brush cleaning device, immediately before stopping the supply of DC voltage to both flicker bars 6 and 6', an AC cylinder pressure of a specific frequency is applied to the flicker bar 6 and 6', and the other flicker bar is grounded. A brush cleaning method for an electrophotographic copying machine, characterized in that the brush cleaning method for an electrophotographic copying machine is characterized in that the brush cleaning method for an electrophotographic copying machine is characterized in that the passage of toner-containing air between the flicker bars 6 and 6' is stopped.