JPS6311259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a static eliminator that is disposed in a paper transport path of, for example, an electrophotographic copying machine or printer, and removes static electricity from the paper that passes through the transport path.

[Prior art]

Generally, in the above-mentioned electrophotographic copying machines and the like, paper is often unnecessarily charged due to friction caused by rubber rollers, heating during fixing, and the like. This kind of unnecessary charging of paper can cause the machine to malfunction, and can significantly impair the operability of the operator when organizing paper.In order to prevent this, the development of static eliminators has been progressing for some time. I've been exposed to it.

One of the devices currently in practical use is a so-called self-discharge promoting type static eliminator that discharges electrical charges on paper through electrodes made of a large number of thin fibrous conductors. Such a static eliminator has a simple configuration and is advantageous in terms of cost, so it is currently used in many copying machines and printers.

However, not all problems have been solved with the advent of the above-mentioned static eliminator.

In other words, in the case of the static eliminator, when the charged potential on the surface of the paper is high, it exhibits a good static neutralizing effect, but when the charged potential is low, it exhibits almost no effect. It was necessary to bring the conductor into contact with the surface of the paper, and to discharge the electrical charge through this contact leakage. As a result, the fibrous conductor is subject to severe wear, and the conductor may become detached or broken, making it unavoidable to use the fibrous conductor for a long period of time. Furthermore, new problems have arisen, such as the fact that the fibrous conductors that have fallen out or broken adhere to electrical circuits in the machine, interfering with the normal operation of the machine.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a static eliminator that can effectively eliminate static electricity from any sheet of paper with a surface charge potential, and that can be used for a long period of time while maintaining safety.

[Structure of the invention]

In this invention, focusing on the fact that the static elimination effect of the static eliminating device is proportional to the electric field strength between the electrodes and the paper, another second electrode is provided at a position facing the electrodes while sandwiching the paper. A probe is provided to apply a DC voltage that increases the electric field strength to the second electrode, and a probe is provided to detect the surface charge potential of the paper, and the voltage is applied to the second electrode based on the detected value. to control the value of the DC voltage. As a result, the electrical charges on the surface of the paper can be easily transferred to the electrode made of the many thin fibrous conductors mentioned above, that is, the first electrode, and even if this potential is low, the charges can be easily transferred to the first electrode. In addition to being effectively discharged, it is also possible to remove static electricity from various types of paper whose charged amounts are not necessarily constant, with an efficiency commensurate with the respective charged amounts. Although the shape of the second electrode is arbitrary, it is preferable that the second electrode has a plate shape in this device in which paper is the object of static elimination.

〔Effect of the invention〕

As described above, according to the static eliminator of the present invention, the static elimination efficiency is significantly improved, and for this reason, it is possible to realize effective static elimination without bringing the first electrode into contact with the paper surface. Become.
Therefore, the above-described wear, detachment, and breakage of the first electrode can be avoided, and the static eliminator can be used safely and over a long period of time. Furthermore, due to the above-mentioned improvement in static elimination efficiency, it is possible to use a material with a high resistance value as the fibrous conductor used as the first electrode. Even if something happens, the risk of it becoming serious is low. In addition, it is possible to effectively eliminate charges on any paper with an amount of charge at an efficiency commensurate with the amount of charge on each paper, so that it is possible to always eliminate charges on these various papers to a surface potential below a certain level.

〔Example〕

First, the principle of this invention will be explained with reference to FIGS. 1, 2, and 3.

FIG. 1 shows that, like a conventional device, only the first electrode 1 consisting of a large number of thin fibrous conductors is connected to the arrow F in the figure.
This figure schematically shows the structure and operation of a static eliminator that discharges the electrical charges on paper PA moving in direction 1, and V→ in the figure
The surface charge potential of PA is E→, which is the same paper PA and the first one above.
d indicates the electric field strength between the paper PA and the first electrode 1, and d indicates the distance between the paper PA and the first electrode 1, respectively.

Therefore, in the case of this device, the electric field strength E→ is expressed as E→=V→/d, and since the static elimination effect in this device is proportional to this electric field strength E, the static elimination effect of the device is ultimately , and if this is A _p , it will be expressed as A _p =kE→=kV→/d (k is a proportionality constant). That is, as the charging potential V→ becomes higher or the distance d becomes shorter, the electric field strength E→ increases, and the static elimination effect A _p also improves.

On the other hand, in FIG. 2, a second electrode 2 is further provided at a position facing the above-mentioned first electrode 1 while sandwiching the paper PA, and a DC power source 3a is connected to the second electrode 2. This figure schematically shows the structure and operation of a static eliminator that applies a bias potential V→ _p in the same direction as the surface charged potential V→ to discharge the electrical charges on the paper PA moving in the direction of the arrow F1 in the figure as above. This is shown in .

Therefore, in the case of this device, the electric field strength E→ is expressed as E→=(V→+V→ _p )/d, and the static elimination effect of the device A _p
Also, A _p =kE→=k(V→+V→ _p )/d (k is a proportionality constant). That is, in the case of this device, compared to the device shown in FIG. 1, the static elimination effect is increased by the bias potential V→ _p applied via the second electrode 2. Depending on the level of this bias potential V→ _p , it goes without saying that it is possible to eliminate static electricity from any sheet of paper with a surface charge potential, but it does not necessarily mean that the fibrous conductor constituting the first electrode 1 can be removed from the paper PA.
This means that effective static elimination is possible even if the fibrous conductor is not in contact with the surface of the conductor, and even if the fibrous conductor is made of a material with a high resistance value.

Furthermore, Fig. 3 shows the paper sheet of the apparatus shown in Fig. 2.
A probe for detecting the charged potential on the surface of the paper PA is provided at a position facing PA, and a bias potential V is applied from the DC power supply 3b to the second electrode 2 based on the detected value of the charged potential on the paper surface by this probe. 1 schematically shows the structure and operation of a static eliminator according to the present invention in which the value of _p is changed.

In the case of this device, as well as the device shown in Fig. 2,
The electric field strength E→ between the paper PA and the first electrode 1 is expressed as E→=(V→+V→ _p )/d, and the static elimination effect A _p is also expressed as A _p =kE→=k(V→ +V→ _p )/d (k is a proportionality constant). However, in this device, the value of the bias voltage V→ _p can be arbitrarily changed according to the value of the surface charge potential V→ of the paper PA, so the charging In other words, it is now possible to set the static elimination effect A _p commensurate with the value of the same potential V → for any sheet of paper with a surface charge potential V →, and as a result, it is possible to always eliminate static electricity on these papers to a surface potential below a certain level. become able to.

FIG. 4 shows, as an embodiment of the static eliminator according to the present invention, a configuration in which the static eliminator is applied to a paper ejection section of an electrophotographic copying machine.

In FIG. 4, the copying machine 100 includes a photoconductor drum 101, a charging corotron 102 for charging the photoconductor drum 101, a lamp 103 for irradiating and scanning a placed document OR, and a lamp 103 for scanning and irradiating a placed document OR, and directing this reflected light to the photoconductor drum. Optical systems 104a, 104b, and 104c expose the surface of photoreceptor drum 101 to light, a developing device 105 develops an electrostatic latent image formed on the surface of photoreceptor drum 101 by the exposure, and the developed image is transferred to various conveyance rollers. A transfer corotron 106 that transfers the image onto the conveyed paper PA, a static eliminating corotron 107 that neutralizes the surface of the photosensitive drum 101 after the transfer, and a static neutralizing corotron 107 that neutralizes the surface of the photosensitive drum 1 after the static neutralization.
A cleaning device 108 that cleans the surface of the paper PA, a fixing device 109 that fixes the transferred image by heating the transferred paper PA, and each of the above-mentioned devices to ensure that these operations related to copying are executed smoothly. This is a well-known electrophotographic copying machine equipped with a controller 110 for general control, and a first electrode 1 made of a large number of thin fibrous conductors.
0, a second electrode 20 made of a plate-shaped conductor, a DC power supply 30 for applying a DC voltage to the second electrode 20, a resistor 31 for dividing the DC voltage, and a relay coil. When a corresponding coil among A to D is excited, a contact piece corresponding to the coil is closed to apply a predetermined divided voltage by the resistor 31 to the second electrode 20. Relay circuit 3
2, a probe 40 that detects the surface charge potential of the paper PA passing through the paper transport path PAL, and a reference value preset in four stages, for example, by using an appropriate comparator or the like to set the potential level detected by the probe 40 to a reference value. Compare, and the detected potential level is
Based on the level determination circuit 41 that determines which of the level areas divided into stages it belongs to, and the determination result by the level determination circuit 41, the paper is treated as having a surface below a certain level, regardless of the amount of charge. DC voltage (divided voltage) that eliminates static potential
The static eliminator of the present invention includes a relay selection circuit 42 that selectively excites the relay coils A to D of the relay circuit 32 so that the voltage is applied to the second electrode 20, and performs static neutralization based on the above-described principle. Same 4th
As shown in the figure, the first and second electrodes are connected to the paper discharge section of the copying machine 100 so that the charges on the paper PA charged by the fixing can be effectively discharged through the first electrode 10. In such a manner that the electrodes 10 and 20 respectively sandwich the conveyance path PAL of the paper PA, and in such a manner that the surface charge potential of the paper PA passing through the conveyance path PAL can be detected in advance by the probe 40. It is arranged. However, in the static eliminator of this embodiment, the above-described controller 110 controls the excitation timing of the relay coils A to D by the relay selection circuit 42, that is, the DC voltage application timing to the second electrode 20, as well as the above-described series of copying operations. The charge removal based on the above-mentioned principle is performed only when the paper PA passes between the first and second electrodes 10 and 20. ing. In addition, as an enable signal for this relay selection circuit 42, for example, the probe 4
Of course, it is also possible to use a zero detection signal, a power-on signal, or the like. Furthermore, in this embodiment, for safety reasons, the second electrode 20 to which a high voltage is applied is covered with an insulator 21 such as plastic.

By providing the static eliminator according to the present invention in the manner described above, it is possible to effectively and reliably eliminate static electricity from the paper PA discharged from the copying machine 100, and furthermore, the paper PA discharged by the operator thereafter can be effectively and reliably neutralized. It can bring great convenience to the organization.

If the above-mentioned copying machine is a double-sided copying machine, the static eliminator of this embodiment can be further provided in front of the paper reversing mechanism to eliminate unnecessary charging of the paper. Malfunctions and paper jams can be effectively avoided.

Furthermore, in the above embodiment, the second electrode 2
Although the configuration is such that the DC voltage applied to 0 is changed in stages using the voltage dividing resistor 31 and the relay circuit 32, the point is that the value of the DC voltage is changed based on the potential level detected by the probe 40. Any configuration may be used as long as it can be controlled; other configurations, such as a configuration in which the DC voltage is changed in an analog manner based on the detected potential level, may also be adopted depending on the actual situation. can do.

Furthermore, the use of the static eliminator according to the present invention is as follows:
It is not limited to copying machines as described above, but can also be used as an output device or an internal processing device of other printers that have a structure in which paper is easily charged.
Furthermore, it can be widely applied as a portable stand-alone device.

[Brief explanation of the drawing]

1, 2, and 3 are explanatory diagrams showing the principle of the static eliminator according to the present invention, and FIG. 4 shows an embodiment of the static eliminator according to the present invention. It is a schematic diagram showing a configuration when applied to a discharge section. 1, 10... fibrous conductor which is the first electrode,
2, 20... A plate-shaped conductor that is a second electrode,
21...Insulator, 3a, 3b, 30...DC power supply, 31...Resistor, 32...Relay circuit, 4,
40...Probe, 41...Level judgment circuit, 4
2... Relay selection circuit, 100... Copying machine, 10
1... Photosensitive drum, 102... Charging corotron, 103... Lamp, 104... Optical system, 10
5...Developing device, 106...Corotron for transfer,
107... Corotron for static elimination, 108... Cleaning device, 109... Fixing device, 110... Controller, PA... Paper, PAL... Paper transport path,
OR... Manuscript.

Claims (1)

[Scope of Claims] 1. A static eliminator that discharges electrical charges on a sheet of paper via a first electrode, comprising a probe that detects a surface charge potential of the sheet of paper, and a probe that holds the sheet of paper between the first electrode and a second electrode disposed at an opposing position; a power supply circuit that applies a DC voltage to the second electrode to increase the electric field strength between the sheet of paper and the first electrode; and the probe. A static eliminator comprising: a voltage control circuit that controls the value of the DC voltage based on the detected value. 2. The static eliminator according to claim 1, wherein the first electrode is made of a large number of thin fibrous conductors, and the second electrode is made of a plate-like conductor.