JPH031798B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a high frequency static eliminator that removes static electricity by applying a positive or negative high frequency high voltage to a static neutralizing electrode.

"Prior art and its problems" Conventionally available low-frequency static eliminators cannot extract a sufficient high voltage without using a large transformer, so the transformer takes up most of the space in the power supply section. However, it was not possible to miniaturize the device, and the energy loss was large. In addition, in order to cut off the power supply when an overcurrent flows through the static eliminator, a current detector is installed between the power supply and the static eliminator electrode of the static eliminator.
When a current exceeding a predetermined value flows between the power supply section and the static elimination electrode, the power supply section is cut off via a relay. Therefore, in the static eliminator, even if a short circuit occurs between the static eliminator electrode and the ground electrode due to corona discharge or the like, the current detector often does not operate, posing a safety problem.

An object of the present invention is to provide a high-frequency static eliminator that can be miniaturized and that can accurately cut off the power supply when a short circuit occurs between the static eliminator electrode and the ground electrode due to corona discharge or the like.

"Means for Solving the Problems" The high-frequency static eliminator of the present invention includes a rectifier circuit that rectifies AC power supply current, a high-frequency oscillation circuit driven by the DC output of the rectifier circuit, and a booster of the high-frequency output. A high-frequency transformer, a static eliminator that connects a positive or negative static eliminator electrode to the output terminal of this high-frequency transformer, and a voltage that is connected to the ground electrode of the static eliminator and that occurs between it and the ground are compared with a reference voltage, and the voltage that is higher than the reference voltage is determined. This device includes a comparison circuit whose output changes when the output changes to , and a relay circuit which operates in response to a change in the output of the comparison circuit and stops the high-frequency oscillation circuit.

"Operation" When AC power supply voltage is supplied, a high frequency oscillation circuit is driven by the rectified DC output, and the high frequency output is boosted by the static eliminator transformer and applied to the static eliminator electrode of the static eliminator. . When a current exceeding a certain level flows through the ground electrode of the static eliminator, the output of the comparison circuit changes, the relay circuit stops the oscillation of the high frequency oscillation circuit, and a high frequency high voltage is applied to the static eliminator electrode of the static eliminator. It disappears.

"Example" Hereinafter, an example of the present invention will be described in detail based on the drawings.

This high-frequency static eliminator is broadly divided into a power supply section 1, a static eliminator 2, and a control section 3.

The power supply unit 1 generates high frequency high voltage by connecting to a 100V AC power supply and turning on the power switch 4, and includes a filter circuit 5, a rectifier circuit 6, an input side constant voltage circuit 7, and a high frequency oscillation circuit. It consists of a circuit 8, a high frequency transformer 9, and an output side constant voltage circuit 10. The filter circuit 5 is for preventing the high frequency from the high frequency oscillation circuit 8 from flowing back to the 100V AC power supply side, and is composed of a coil 11 and three capacitors 12, and is equipped with a ground terminal 13. There is. The rectifier circuit 6 includes a bridge rectifier 14, a resistor 15, and a smoothing capacitor 16.
Rectify 100V alternating current to direct current. The input side constant voltage circuit 7 is composed of a Zener diode 17, a resistor 18, and a capacitor 19, and generates a constant DC voltage, which is used to drive some circuits of the control unit 3 as described later. used for. The high frequency oscillation circuit 8 includes a diode 20, a starting transistor 21, a control transistor 22,
It consists of a capacitor 23, three resistors 24, and a high frequency transformer 9, and a starting transistor 2
When a direct current rectified by the rectifier circuit 6 flows through 1 and turns on, it generates a high frequency (e.g.
16KHz) voltage. This high-frequency voltage is stepped up by the high-frequency transformer 9, and a positive or negative high-frequency high voltage (for example, 4 KV) is output to the high-voltage output terminal 25a on the secondary side. The output side voltage constant circuit 10 is composed of a diode 26, a constant voltage integrated circuit 27, and a capacitor 28, and rectifies the low voltage output on the secondary side of the high frequency transformer 9, and converts it into a constant voltage to generate a constant DC voltage (for example, 12 V). )
and supplies it to the control section 3 as a driving voltage.

As shown in FIGS. 1 and 2, the static eliminator 2 has a large number of needle-shaped static eliminator electrodes 30 implanted in a horizontally long insulating base 29, and conductive grounding substrates 31 serving as ground electrodes on both sides of the insulating base 29. The static eliminating electrode 30 is connected to the high voltage output terminal 25a of the high frequency transformer 9, and the grounding board 31 is grounded. Therefore, in the static eliminator 2, a high frequency high voltage of, for example, 16 KHz/4 KV is applied to the static eliminator 30, and static electricity is removed from the object to be neutralized that is opposed to the static eliminator 30 without contact.

The control unit 3 includes a ground current extraction circuit 32, a first comparison circuit 33, a second comparison circuit 34, a light emitting diode 35 for danger display, and a photocoupler 36. The earth current extraction circuit 32 is configured by connecting a capacitor 37, two resistors 38, and a diode 39 between the earth terminal 25b on the secondary side of the high frequency transformer 9 and the earth board 31 of the static eliminator 2, The current flowing from the ground base 31 to the ground is integrated, rectified, and supplied to the first comparator circuit 33. The first comparison circuit 33 includes an operational amplifier 4
0, a resistor 41 connected to its positive input terminal,
Resistor 4 connected between the positive input terminal and output terminal
A reference voltage is input to the negative input terminal of the operational amplifier 40. be done. The output terminal of the operational amplifier 40 is connected to the light emitting element 3 of the photocoupler 36 via a resistor 46.
6a. Also, photocoupler 36
The light receiving element 3 cooperates with the control transistor 22 to form a non-contact relay circuit.
6b is connected to the base of this transistor 22 and further connected to the input side constant voltage circuit 7.

Therefore, in the static eliminator 2, the static eliminator electrode 30
When a short circuit occurs between the ground board 31 and the ground board 31 due to corona discharge, an overcurrent flows between the ground board 31 and the ground, and the resulting voltage exceeds the reference voltage, the output of the operational amplifier 40 changes from HIGH to LOW.
The light emitting element 36a of the photocoupler 36 stops emitting light, and its light receiving element 36b is turned off. Therefore, the control transistor 22 is turned on, and accordingly, the pace of the starting transistor 21 is grounded, and the starting transistor 21 is turned off.
The oscillation operation of the high frequency oscillation circuit 8 automatically stops,
High frequency high voltage is no longer applied to the static elimination electrode 30. At this time, the light emitting diode 35 lights up at the same time.

The second comparator circuit 34 is also shown in a simplified manner, but like the first comparator circuit 33, it includes a resistor etc. in addition to an operational amplifier 48, and the input side of this operational amplifier 48 is connected to the ground terminal 25b of the high frequency transformer 9. When the voltage on the primary side of the high-frequency transformer 9 increases or decreases by, for example, 10% or more, the output of the operational amplifier 48 changes from HIGH to LOW, and the oscillation operation of the high-frequency oscillation circuit 8 is stopped in the same way as above. It is something.

"Effects of the Invention" As detailed above, the present invention has the following effects.

The high frequency oscillation circuit generates high frequency oscillation, the output is boosted by the high frequency transformer, and the high frequency high voltage is applied to the static eliminator electrode of the static eliminator. Compared to those using low-frequency transformers, the overall size can be made smaller, and there is less energy loss.

A current detector is used to extract the current flowing between the ground electrode of the static eliminator and the ground, compare it with a reference value using a comparison circuit, and automatically stop the high frequency oscillation circuit using a relay circuit when the current exceeds a predetermined value. Compared to conventional devices that control the static eliminator by connecting it to a transformer and static eliminator electrode, it is possible to accurately stop the application of high frequency and high voltage when an overcurrent flows in the static eliminator, making it highly safe.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, with FIG. 1 being an electric circuit diagram and FIG. 2 being a front view of a static eliminator. 2... Static eliminator, 6... Rectifier circuit, 8... High frequency oscillation circuit, 9... High frequency transformer, 25a... Output terminal of high frequency transformer, 30... Static elimination electrode, 3
1... Earth board (earth electrode), 33... Comparison circuit, 36... Photocoupler constituting the relay circuit.

Claims (1)

[Claims] 1. A rectifier circuit that rectifies AC power supply current, a high-frequency oscillation circuit driven by the DC output of this rectifier circuit, a high-frequency transformer that boosts the high-frequency output, and a positive or negative static eliminator at the output terminal of this high-frequency transformer. A static eliminator to which the electrode is connected, a comparison circuit that is connected to the ground electrode of the static eliminator and compares the voltage generated between it and the ground with a reference voltage, and whose output changes when the voltage exceeds the reference voltage, and the output of this comparison circuit. A high-frequency static eliminator comprising: a relay circuit that operates in response to a change and stops the high-frequency oscillation circuit.