JPS59176761A - Corona discharging device - Google Patents

Abstract

PURPOSE:To eliminate the need for periodic cleaning operation by allowing oscillations of an ultrasonic oscillator to operate on a corona discharge line or grid line. CONSTITUTION:A shield plate 10 which has U-shaped cross section, insulating support bases 11 provided integrally to both its end parts, the ultrasonic oscillator 12 fitted to one insulating support base 11, and a connector 13 for external electric path connection to the other insulating support base 11 are provided in one body respectively. One terminal is fitted to the insulating base by a fixing pin 15, and the other terminal is fitted to the connector 13 while pressed against the ultrasonic oscillator 12 through an insulating member 16 to extend the corona discharge line 14 between the left and right insulating support bases 1, and the discharge line 14 is oscillated by the vibrator 12 in a diameter direction. Oscillation circuits 18a and 18b which differ in oscillation frequency and peak value of oscillation output are connected to the ultrasonic vibrator 12, and the oscillation circuits 18a and 18b and a high voltage transformer 19 are controlled by a timing signal circuit 20.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a corona discharge device, for example, a corona discharge device used in an electrophotographic copying machine or the like to uniformly charge or eliminate static electricity on the surface of a photoreceptor.

Conventionally, this type of corona discharge device is a corotron device consisting of a discharge wire connected to a high-voltage power source and a shield plate surrounding the discharge wire, or a corotron device with a discharge current control member (hereinafter referred to as a grid wire). A scorotron equipped with a scorotron is known.

Since these devices use corona discharge due to the application of high voltage, the dust collection effect is unavoidable and may cause foreign matter to adhere to the discharge wires, grid lines, shield plates, etc., such as developer, oxides from the discharge, dust in the air, etc. It has the disadvantage that it is prone to staining and causes uneven static elimination characteristics during charging. Therefore, regular cleaning work is required to maintain stable charging characteristics, which causes inconvenience in electrophotographic copying machines and the like.

The present invention has been proposed in view of the above, and has excellent durability such that stable discharge characteristics are maintained for a long period of time without requiring periodic cleaning work. The object of the present invention is to obtain a corona discharge device that can efficiently remove foreign matter having a diameter of submicrometers of 4 microns in a short time.

FIG. 1 is a diagram schematically showing an electrophotographic copying machine to which the corona discharge device of the present invention is applied. A photoreceptor 1 is supported rotatably in the direction of the arrow, and around the photoreceptor there is a light image reflected from an original 4 illuminated by a charger 2 and a lamp 3 that uniformly charge the surface of the photoreceptor. A short focus lens array 5 that forms a latent image by forming an image on the surface of the photoreceptor, 2. A developer 6 that develops the latent image, and 2. A developing device 6 that is fed in synchronization with the rotation of the photoreceptor l. Electrophotographic process equipment such as a transfer material 7, a transfer charger 8 for transferring the visible image on the photoreceptor to the transfer material, and a through cleaning blade 9 for removing residual toner on the photoreceptor are sequentially arranged. -) 2. The transfer material 7 is fed through a fixing device (not shown), and the transferred image is fixed on its surface.

FIG. 2 is a longitudinal cross-sectional view showing an embodiment of the corona discharge device of the present invention used as the charger 2 and the transfer charger 8, and FIG. 3 is a cross-sectional view taken along line 2--2 in FIG. In Figures 2 and 3, 10 is a shield plate having a U-shaped cross section, and 11 is an insulating support stand integrally provided at both ends of the shield plate. Connectors 13 for connecting external electric circuits are integrally provided on each of the support stands. The - end of 14 is attached to an insulating support with a fixing pin 15, and the other end is attached to the ultrasonic transducer 12 through an insulating member 16. This is the connector Rona discharge wire. The vibrator vibrates in the direction of the arrow in the figure, and therefore the discharge wire 1
4 is subjected to vibration in its diametrical direction (lateral direction). Reference numeral 17 denotes a lid made of insulating resin attached to the insulating support surface facing the opening of the shield plate IO. 18a and 18b are oscillation circuits connected to the ultrasonic transducer 12, and have different oscillation frequencies, peak values of oscillation output, etc. 19 is a high voltage transformer connected to the connector 13; 20 is a timing signal circuit for controlling the oscillation circuits 18a, 18b and the high voltage transformer 19; Note that although two oscillation circuits are provided in this embodiment, the present invention is not limited to this.

For example, as shown in FIG. 4, the timing signal circuit 20 includes variable resistors Ra to Re that set the operating time of the A-C mode and variable resistors that set the stop time of the A-C mode on the input side of the microcomputer MC. This configuration includes Ra-Re and operates oscillation circuits 18a to 18c connected to the output side of microcomputer MC.

As the ultrasonic transducer 12, materials exhibiting piezoelectric properties such as barium titanate, lead zirconate titanate (PZT), lead-lanthanum, zircon-titanium oxide mixture (PLZT), and organic materials are used. It will be done. Further, a single plate may be used as the vibrator, or it is also possible to use a double laminated plate.

The oscillation circuits 18a to 18c (18c is shown only in FIG. 4) may apply an alternating electric field or an electric field close to it to the ultrasonic transducer 12. The direction of vibration of the ultrasonic vibrator may be in the horizontal direction of the arrow (direction perpendicular to the discharge line), but
The direction of vibration is not particularly limited as long as the vibration can be transmitted to the corona discharge wire 14, and it may be perpendicular to the corona discharge wire 14, parallel to it, or diagonal to the corona discharge wire 14.

The amplitude of the corona discharge wire is about several gm, and its frequency is effectively several tens of KHz, but is not limited to this, and can be used in the range from several KHz to several MHz.

The operation of the corona discharge device of the present invention will be explained below with reference to the timing chart shown in FIG. When a copy signal is input by the user (point t1 in FIG. 5), the photoreceptor l starts rotating, and at the same time the timing signal S1 from the timing signal circuit 20 is input.
for several seconds (Ta time in Figure 5 set by variable resistor Ra)
The oscillation circuit 18a is activated and the oscillation output of this oscillation circuit is supplied to the ultrasonic transducer 12. When the ultrasonic vibrator 12 receives an oscillation output, it vibrates in A mode due to its piezoelectric characteristics.
The corona discharge wire 14 is vibrated in the direction of the arrow in FIG. 2 to shake off and remove foreign matter that has adhered to the corona discharge wire while it is left standing.

The oscillation circuit 18a becomes inactive after a time period L Ta has elapsed, and stops the vibration of the ultrasonic transducer 12 in the A mode.

Next, the oscillation circuit 18b is activated with the next timing signal S2 from the timing signal circuit 20 after 1 hour set by the variable resistor Ra, and the oscillation output of this oscillation circuit causes the ultrasonic transducer 12 to vibrate in B mode. The corona discharge wire 14 is operated for several seconds (time Tb in FIG. 4 set by the variable resistor Rh), and the corona discharge wire 14 is vibrated by this B-mode vibration to remove foreign matter that could not be removed by the A-mode vibration. Remove. A flowchart of the above cleaning operation (including the C mode using the oscillation circuit 18c shown in FIG. 4) is shown in FIG.

Note that the above-mentioned A-mode vibration is a vibration that can be generated by an alternating electric field of several KHz, and B-mode vibration is a vibration of several tens of kilohertz.
This is a vibration that can be generated by an alternating electric field of KHz. In other words, A
The low frequency vibration of the moat can remove relatively large foreign particles, while the high frequency vibration of the B mode can remove the foreign matter mentioned above.
It has strong adsorption power and can remove foreign matter with a particle size of submicron to several microns that could not be removed by mode vibration.

Thereafter, the high voltage transformer 19 is activated by the next timing signal S.5 output from the timing signal circuit 20, and the high voltage output of this high voltage transformer is applied to the corona discharge wire 14 via the connector 13, and the corona discharge wire A corona discharge is generated to uniformly charge the surface of the rotating photoreceptor. As a result, the photoreceptor 1 completes a pre-levelling rotation called a pre-rotation, and then enters a copy rotation after γ to perform a copying operation. After this, a post-run-in rotation or post-rotation begins, and at the same time as the post-run-in rotation ends, the high pressure is turned off to 0FFe.

After a few seconds, the oscillation circuits 18a and 18b operate in response to the timing signals S, S2 from the timing signal circuit 20, and the output of each oscillation circuit operates the vibrator in A mode for several seconds (Ta). The corona discharge wire is excited and vibrated in B mode for several seconds (Tb) to remove large and small foreign matter that adhered to the corona discharge wire during copying rotation very efficiently, and is left alone.

The vibration times of the A mode and B mode may be the same time or may be different times. In addition, it is possible to combine not only the two types of motes A and B, but also the vibrations of various modes of light of the oscillation frequency and the peak value of the oscillation output (drive voltage of the ultrasonic vibrator).

The manner in which the corona discharge wire 14 is vibrated is not limited to the above-mentioned embodiment, and may be performed during the forward rotation and rear rotation of the photoreceptor, as well as during the copy rotation. In other words, even if the corona discharge wire 14 is vibrated when a high voltage is applied, the amplitude has little effect on the charging characteristics, etc., and it is possible to vibrate for an arbitrary period of time or for a fixed period of time depending on the timing signal from the timing signal circuit 20. It is.

The oscillation circuits 18a-18c receive timing signals s1 and S2.
A single oscillation circuit may be used as long as it can automatically vary the oscillation frequency or the peak value of the oscillation output by receiving . Furthermore, the control of the oscillation circuits 18a to 18c may be performed by detecting, for example, the number of copies made or the cumulative value of one hour of copying, and using a signal when this detected value reaches a predetermined value, without depending on the timing signal. Alternatively, a signal emitted when a user detects dirt on an image or operates a switch, etc. on the control section of the copying machine at any time for regular maintenance may be used. . Furthermore, it is also possible to keep the ultrasonic transducer in operation at all times during the operation of the copying machine.

FIG. 7 is a longitudinal cross-sectional view showing another embodiment, in which another ultrasonic vibrator 21 is provided in addition to the ultrasonic vibrator 12 on an insulating support 11, and the ultrasonic vibration Attach one end of the corona discharge wire 14 to -f 21 with a fixing pin 23 via an insulating member 22, and attach the oscillation circuit 1 to the ultrasonic vibrator 21.
This is a configuration in which the output ends of 8b are connected.

The ultrasonic vibrator 21 vibrates in the illustrated direction different from that of the ultrasonic vibrator 12, that is, vibrates the discharge wire 14 in a direction that strengthens or weakens its vibration +1, and cannot be removed by the vibration by the ultrasonic vibrator 12. This removes foreign matter. In other words, the vibration of the ultrasonic transducer 12 in the illustrated direction removes foreign substances with small particle diameters, and the large vibration of the ultrasonic transducer 21 in the tensile direction removes foreign substances with large particle diameters. By efficiently combining different vibrations, corona discharge can be maintained evenly and stably.

Fig. fiS8 shows a grid stretched on the discharged surface side of the corona discharge wire 14! This is an example in which the fixed bottle 25 is attached to a plurality of holes while the I24 is pressed against the ultrasonic vibrator 26 provided on the lid 17 via the insulating member 27. In this embodiment, the grid line 24 is vibrated in the direction of the arrow shown in the figure by the vibration of the ultrasonic transducer to remove foreign matter attached to the grid line. In this example, the configurations shown in FIGS. 2 and 7 of the nIJ description are added to make it possible to vibrate the corona discharge wire 14 at the same time. In FIG. 8, 18a' and l8b' are oscillation circuits, and 20 is a timing signal circuit.

The corona discharge device of the present invention can be applied not only to various chargers used in copying machines, such as negative chargers, secondary chargers, post chargers, and transfer chargers, but also as pre-neutralization chargers.

As described above, the present invention causes the corona discharge wire or the Grinod wire to vibrate in different modes at any time or for a certain period of time, and by this vibration, foreign matter attached to these wires is effectively shaken off. The amount of adhesion is extremely reduced, and a stable discharge state, that is, uniform discharge characteristics, can be maintained for a long period of time without the need for regular cleaning work, and foreign matter is less likely to be baked into the corona discharge wire due to the heat during discharge. This has the effect of improving the life of the corona discharge wire itself, that is, the durability of the corona discharge device itself.

[Brief explanation of the drawing]

Figure 1 shows a very schematic diagram of an electrophotographic copying machine.
3 is a longitudinal sectional view showing an embodiment of the corona discharge device of the present invention.
The figures are a cross-sectional view along the line ■-■ in Figure 2, Figure 4 is a timing signal circuit diagram, Figure 5 is a timing diagram, Figure 6 is a flowchart, and Figures 7 and 8 are corona discharge according to the present invention. FIG. 7 is a partial vertical cross-sectional view showing another embodiment of the device. 12, 21, 26 are ultrasonic transducers, 14 is a corona discharge wire, 18a-18c, 18a'*18b are oscillation circuits, 19
is a high voltage transformer, and 2o and 20' are timing signal circuits.

Claims (1)

[Claims] (1) A configuration in which the vibration of an ultrasonic transducer is applied to a corona discharge line or a grid line, and -1- The corona discharge is caused to cause vibrations in different modes in the line or grid line at any time or for a fixed time. Characteristic corona discharge device.