KR940009508B1 - Control circuit for neon lamp - Google Patents

Abstract

The control circuit protects an electronic device from high voltage of a step-up transformer. The circuit includes a switch which rectifies alternating input, an oscillating circuit which generates alternating distorted wave, and a control circuit which outputs step-up alternating distorted wave through the step-up transformer. The circuit includes the 1st and 2nd field effect transistors which alternatively operate on/off, a square wave generator which has charging/ discharging means, and a duty control means which adjusts the charging/ discharging speed of a charger.

Description

Neon tube control circuit

1 is a block diagram of a neon tube control circuit according to the present invention.

2 is a detailed configuration of the neon tube control circuit according to the present invention.

3 is a detailed configuration diagram of the oscillation circuit portion in the neon tube control circuit according to the present invention.

FIG. 4 is an explanatory diagram for explaining waveforms generated in each section in the oscillation circuit section in FIG.

5 is a voltage waveform diagram of each part in the oscillation circuit of FIG. 3 and a final output waveform diagram of the neon tube control circuit according to the present invention.

6 is a configuration diagram for explaining the operation of the switching unit and the boost transformer in the neon tube control circuit according to the present invention.

7 is a schematic configuration diagram of a neon tube for explaining the J.B phenomenon.

8 is a schematic configuration diagram of a neon tube control circuit according to the prior art.

9 is an output waveform diagram of each of the prior art according to FIG.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit of an electronic neon transformer, and more particularly, to a neon tube control circuit capable of eliminating the J.B phenomenon in which light and light are periodically repeated in a neon tube, and the M.M phenomenon in which the ends of the electrode and the neon tube are black.

In general, in neon tubes such as neon gas filling tubes, argon gas filling tubes, and mercury injection tubes controlled by neon transformers, the speed of beam propagation in the neon tubes is considerably higher than the voltage applied between the electric field, that is, the anode of the neon tube. Because of the slowness, when the electric field of the neon tube anode is a fully symmetrical alternating current, the beam progresses in the neon tube, resulting in the contrast of brightness in the neon tube. In other words, the frequency of the AC output of the transformer applied to the neon tube is approximately 20-40 KHz, and the brightness of the light is bright and dark at regular intervals along the neon tube due to the resonance phenomenon caused by the change in the speed of the beam in the neon tube and the electric field intensity in the tube. Losing phenomenon, that is, JELLY BEANING (hereinafter referred to as JB phenomenon) is caused. An explanatory diagram showing this J.B phenomenon in detail is shown in FIG.

As a conventional technique for eliminating the J.B phenomenon in which bright and dark portions appear at regular intervals along the neon tube, there is a configuration in which two diodes connected in series are connected in parallel to the output side of the transformer as shown in FIG.

In addition, as another conventional technique for removing such a JB phenomenon, as shown in FIG. 8B, a parallel-connected diode and capacitor are connected in series to one side of the transformer output side or a parallel-connected diode and capacitor pair is connected to the transformer output side. There is a configuration in which both ends are connected in series.

In addition, as another conventional technique for removing such a JB phenomenon, as shown in FIG. 8C, two series-connected capacitors are connected in parallel to one side of the output side of the transformer, and two diodes connected in series are connected to the output side of the transformer. There is a configuration connected in parallel to the other side.

Therefore, the above-described conventional techniques are configured by combining a diode or a diode and a capacitor on the output side of the transformer, thereby generating a voltage having an asymmetric waveform.

The waveform diagram of the asymmetric voltage occurring at the output side of these prior arts is shown in detail in FIG. In the same figure, a, b, and c are output waveform diagrams respectively corresponding to the configuration diagrams of a, b, and c shown in FIG. 8A, respectively. Therefore, these prior arts remove the J.B phenomenon in which bright and dark portions of light appear at regular intervals along the neon tube by applying a voltage having an asymmetric waveform to the neon tube, as can be clearly seen from the same drawing.

However, these prior arts only focus on eliminating the JB phenomenon. For example, when a voltage having an asymmetric waveform is applied to a neon tube filled with mercury and argon gas, mercury vapor in the tube where -2 is an element is obtained. Is charged By moving to the electrode side, the moved mercury particles The phenomenon in which the end portions of the electrode and the tube are blacked by being deposited on the electrode portion, that is, a phenomenon called MECURY MIGRATION, is not considered at all. Therefore, if a predetermined time passes after the neon tube is installed and operated, the mercury vapor in the tube Is charged By moving to the electrode side, the moved mercury particles The deposition on the electrode portion caused a problem in which mercury micronization (hereinafter referred to as MM phenomenon), in which the end portions of the electrode and the tube were black, was caused.

Therefore, although the prior arts are popular with neon tubes to eliminate the JB phenomenon, a voltage having an asymmetric waveform is applied to the neon tube by applying a voltage having an asymmetric waveform to the neon tube, causing an MM phenomenon to occur. The end of the neon tube is black, which is not only aesthetically pleasing, but also has the disadvantage that the brightness of the neon tube is lowered.

In addition, in the prior art in which a diode or a diode and a capacitor are combined on the output side of the transformer to eliminate the JB phenomenon, a diode having asymmetric waveform is generated by combining the diode or the diode and the capacitor on the output side of the transformer. High pressure is applied to the capacitors and these components may be destroyed.

The present invention has been devised in view of the problems caused by the prior art, and the brightness and darkness are periodically repeated in a neon tube by applying a voltage having an alternating distortion wave whose square wave having different vertical widths varying in a predetermined period to the neon tube. It is an object of the present invention to provide a neon tube control circuit capable of eliminating not only the JB phenomenon but also the MM phenomenon caused by the prior art of applying a voltage having an asymmetrical square wave to remove the JB phenomenon.

In order to achieve the above object, the present invention rectifies an AC input through a rectifying circuit, inputs it to a switching means, presses down a part of the AC input, rectifies it into a half-wave rectified pulse current, and inputs it into an oscillating circuit part. A neon tube control circuit configured to generate an alternating distortion wave based on the half-wave rectified pulse current and input it to the switching means, and output the boosted distortion wave through a boosting transformer connected to an output side of the switching means; The switching means comprises first and second transistors which alternately turn on / off based on an output signal of the oscillation circuit portion; The oscillating circuit section includes a square wave generating means having charge and discharge means for feedback and accumulating and releasing charges by returning a part of its output to generate a square wave signal using the half-wave rectified pulse current as an input signal; Technical means having a duty control means for adjusting the discharge rate.

Therefore, the neon tube control circuit according to the present invention is a rectifier circuit for rectifying the noise-free AC input through the filter circuit, and a half-wave rectified by rectifying through the built-in rectifier by stepping down the AC input from which the noise is removed through the filter circuit A duty control voltage generator for generating a signal, an oscillator circuit part for generating alternating distortion waves in correspondence with an output signal from the duty control voltage generator, and an oscillation circuit part connected to the rectifying circuit and simultaneously connected to the oscillation circuit part And a switching unit configured to alternately operate based on a signal, and a transformer for boosting a voltage having this lateral distortion wave (a waveform in which a square wave having a different vertical width varies in a constant period).

In addition, the switching unit in the neon tube control circuit according to the present invention is composed of two field effect transistors which are turned on / off based on the output signal of the oscillating circuit part, and the oscillating circuit part according to the present invention is an output signal from a duty control voltage generator. RS flip-flop generating square wave by inputting the output signal of the duty control voltage generating unit through two comparators to generate alternating distortion wave based on A capacitor and a resistor for duty control for adjusting the charge / discharge speed of the capacitor are provided.

Therefore, in the neon tube control circuit according to the present invention, the AC current from which noise is removed through the filter circuit is input to the duty control voltage generating unit through the rectifying circuit and the first transformer, respectively. The rectified direct current in the rectifier circuit charges the capacitor and biases the first and second field effect transistors.

In the oscillation circuit section, when the signal input from the duty control voltage generation section is at a high level, a part of the output of the oscillation circuit section is traced so that the capacitor which accumulates and discharges the charge becomes faster, while the discharge rate is relatively Since it is delayed, the voltage waveform at both ends of the capacitor becomes a waveform having a narrow rising width (at the time of charging) and a large falling width (at the time of discharge). Therefore, at the output end of the oscillation circuit portion, a square wave of a period in which the high level state is narrow (at the time of charging) and the low level state is wide (at the time of discharge) is output.

On the other hand, in contrast to the above, when the signal input from the duty control voltage generator is at a low level, the charge speed is slowed down because the duty control resistor and the divided voltages of the two resistors are applied to the capacitor. Since the discharge speed is increased by the duty control resistor connected in parallel to the resistor, the voltage waveform at both ends of the capacitor becomes a waveform having a large rising width (at the time of charging) and a narrow falling width (at the time of discharge). Therefore, at the output end of the oscillation circuit portion, a square wave of a period having a wide high level (at charging) and a narrow low level (at discharge) is output.

This square wave signal is then applied to the primary side coil of the second transformer as an alternating distortion wave of pure alternating component in which the spark component is absorbed through the resistor and the DC component is canceled through the other capacitor.

Therefore, the alternating distortion wave output from the oscillation circuit part alternately turns on / off the first and second field effect transistors in the switching part through the second transformer, thereby causing the distortion distortion through the boosting transformer connected to the output side of the switching part. Output wave

As described above, the neon tube control circuit according to the present invention generates a symmetrical wave in which a square wave having a different vertical width is changed at regular intervals through an oscillation circuit portion, and changes its width, and the voltage in the switching portion is changed to a voltage having the alternating distortion wave. And driving the second field effect transistor and applying a boosted voltage having an alternating distortion wave to the neon tube through a boosting transformer interlocked with the switching unit, thereby eliminating the JB phenomenon as well as the JB phenomenon occurring in the neon tube. It is possible to effectively eliminate even the MM phenomenon caused by the above-described prior art, which generates an asymmetric square wave.

Hereinafter, an operation process of the neon tube control circuit according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a neon tube control circuit according to the present invention, in which the reference numeral 10 is a filter circuit, 20 is a rectifier circuit, 30 is a duty control voltage generator, 40 is an oscillator circuit, 50 is a switching unit, 60 Denotes a boost transformer, respectively.

FIG. 2 is a detailed configuration diagram of the neon tube control circuit according to FIG. 1. Hereinafter, the control operation of the neon tube control circuit will be described with reference to FIGS.

First, when a commercial voltage, for example, 90 to 130 V or 180 to 260 V is applied through an input terminal, through a fuse F1 to a filter circuit 10 composed of a capacitor C1, an inductance L1, and a capacitor C2. Since the AC current is input and noise is removed, the noise is fed back to the line side. The output side of the filter circuit 10 is branched in both directions, and an alternating current, in which the joze is removed, is applied to the rectifier circuit 20 through one side thereof. Therefore, through this rectifier circuit 20, the alternating current is rectified as a pulse current, and the output side thereof is connected to the capacitors C3 and C4 connected in series with each other and at the same time the drain of the first field effect transistor Q1 of the switching section 50 and It is connected to the source of the 2nd field effect transistor Q2, respectively.

Here, when an AC current without noise is applied to the first transformer T1 through another side branched from the output side of the filter circuit 10, the AC current stepped down through the first transformer T1 is a duty control voltage. It is input to the generator 30. Therefore, the stepped down AC current is rectified as a pulse current from the rectifier D2 in the duty control voltage generator 30 and input to the oscillator circuit 40 through its output terminal. At this time, the voltage applied to both ends of the capacitor C6 connected between the output side of the rectifier D2 in the duty control voltage generator 30 and the ground is approximately DC 12V. When this voltage is applied to pin 8 of IC U1 in oscillation circuit section 40, resistor R3, variable resistor R4 and capacitor C _T connected in series through pins 2 and 6 of IC U1. By continuously charging and discharging according to the time constant of), the IC U1 generates a square wave output through pin 3, which is its output pin. The square wave output here is a high frequency component of approximately 30 KHz.

3 is a detailed configuration diagram of the oscillation circuit portion in the neon tube control circuit according to the present invention, in which the oscillation circuit portion 40 has a first comparator 42 having a non-inverting terminal connected to Vc and an inverting terminal connected to Vcc. And a second comparator 43 having a non-inverting terminal connected to Vcc and an inverting terminal connected to Vc, an output of the first comparator 42 being input to an R terminal, and an output of the second comparator 43 An RS flip-flop 41 configured to be inputted to the S terminal and an inverter 44 connected to the output terminal Q of the RS flip-flop 41 are included. Here, the output of the inverter 44 is branched so that one is an output and the other is connected between the Vc terminal and the ground through the variable resistor R4 and the resistor R3 and at the same time, the first comparator 42 is fed back to the capacitor C _T connected to the non-inverting terminal of the second comparator 43 and the inverting terminal of the second comparator 43, and connected in parallel to the variable resistor R4 and resistor R3 between the feedback output terminal of the inverter and ground. And a resistance control resistor (RC) connected to the Vc terminal. In addition, the inverting terminal of the first comparator 42 and the non-inverting terminal of the second comparator 43 are commonly connected to Vcc via the voltage divider R11, R12, and R13.

The capacitor C in the oscillation circuit part 3 and the above-described process for the oscillation circuit part 40 according to the present invention having the above-described configuration to generate an alternating distortion wave by inputting the pulse current generated in the duty control voltage generation part 30 as an input. _It will be described below with reference to FIG. 4 showing the waveform generated at _T ) and the output terminal OUT.

First, the operation of the oscillation circuit section will be described assuming that the duty control resistor RC connected to the Vc terminal side in the same figure is not connected.

When the output of the RS flip-flop 41 is at the low level, the output of this low level is inverted through the inverter 44 connected to the output terminal of the RS flip-flop 41 to be at the high level. A part of the inverted high level signal is fed back through the variable resistor R4 and R3 to charge the capacitor C _T , thereby increasing the voltage at the K point. The above voltage is applied to the inverting terminal of the second comparator 43. Therefore, since the output of the second comparator 43 is at a low level, and the output of the first comparator is at a low level, the RS flip-flop 41 is maintained at the previous state, that is, at the low level, and thus, the inverter 44 is maintained. The final output (OUT) also maintains a high level.

In this oscillation circuit section 40, that is, when the output of the flip-flop 41 is at a low level and the output of the inverter 44 continues at a high level, the voltage across the capacitor C _T is further increased. Whereby the potential at point K Since the output of the first comparator 42 to which the non-inverting terminal is connected through the point K becomes high level, the output of the RS flip-flop 41 becomes high level. As a result, the output of the inverter 44 becomes low level. Therefore, when the output of the inverter 44 is at the low level, the electric charge charged in the capacitor C _T is discharged and the potential at the K point is caused by this discharge. If it is lowered below, the output of the first comparator 42 is converted to the low level, but since the voltage levels of the R and S terminals of the RS flip-flop 41 are all low level, the output of the RS flip-flop 41 is in the entire state. That is, since the high level is maintained, the output of the inverter 44 also maintains the low level, so that the capacitor C _T continues to discharge.

Therefore, the capacitor (C _T ) continues to discharge and the voltage at K point When it falls below, since the output of the 2nd comparator 43 becomes a high level, the output of the RS flip-flop 41 will become a low level, and the output of the inverter 44 will become a high level. As described above, the voltage at the K point is reduced by continuous discharge of the capacitor CT. As described above, as described above, the output of the RS flip-flop 41 is at the low level, the output of the inverter 44 is at the high level, and the capacitor C _T resumes charging again.

As described above, when the duty control resistor RC is not connected to the oscillation circuit portion, the voltage across the capacitor C _T is in Since charging and discharging are continued, the charging and discharging speeds are the same, and as shown in FIG. 4A, the voltage waveforms across the capacitor C _T have the same rising and falling widths, so the output The terminal OUT outputs the pulse waveform of the period T with the same width of the high level state t1 and the low level state t2. Where duty is to be.

In the above description of operation, it is assumed that the duty control resistor RC connected to the oscillation circuit part through the Vc terminal is opened. However, the duty control resistor RC is connected between the Vc terminal and the oscillation circuit part 40. When the pulse generated in the duty control voltage generator 30 of the stage is input to the Vc terminal and its potential level is high, the charging speed of the capacitor C _T is increased while the discharge speed is relatively slow. . Therefore, as shown in FIG. 4B, the voltage waveforms across the capacitor C _T are waveforms of which the rising width is narrow (during charging) and the falling width is large (during discharge). Therefore, the output terminal OUT has a high level state t1. The pulse waveform of the period _T is narrowed (at the time of charging the capacitor C _T ) and wide at the low level state t2 (at the time of discharge of the capacitor C _T ). Duty at this time to be.

On the other hand, in contrast to the above, when the input signal input to the Vc terminal is at a low level, the capacitor C _T is charged with a divided voltage between the duty control resistor RC and the resistors R3 and R4, resulting in a slow charging speed. On the other hand, when the capacitor C _T is discharged, the discharge speed is increased by the duty control resistor RC connected in parallel with the resistors R11 and R12. At this time, the voltage waveform appearing at both ends of the capacitor C _T becomes a waveform having a wide rising width (at the time of charging) and a narrow falling width (at the time of discharge) as shown in FIG. A pulse waveform of a period T having a wide t1 and a wide low level t2 is output. Duty at this time to be.

As described above, the oscillation circuit portion 40 of the neon tube control circuit according to the present invention is to perform the charging and discharging operation continuously by the half-wave rectified pulse current input through the Vc terminal, so as to As shown in the figure, the waveform is output.

5 is a waveform diagram showing the waveform of each part in the oscillation circuit portion employed in the present invention and an output waveform diagram of the neon tube control circuit. Each of Vc, C _T and OUT described in the same drawing is an oscillation circuit portion shown in FIG. Waveforms at the Vc terminal, the capacitor C _T and the output terminal OUT of 40 are shown, and V _OUT represents the final output waveform of the neon tube control circuit according to the present invention, shown in FIG.

Then, as described above, the output waveform generated by the oscillation circuit section 40, that is, the pulse wave output from pin 3 of the IC U1 as the pulse current from the duty control voltage generator 30 as an input, is a resistor R6. The spark component is absorbed through and applied to the primary-side coil NP of the second transformer T2 as an alternating distortion wave of pure AC component in which the DC component is canceled through the capacitor C8. Therefore, since the square wave alternating current is applied to the primary coil NP of the second transformer T2, the induced voltage is maintained in the secondary coils NS ₁ and NS ₂ . At this time, since the winding directions of the secondary coils Ns ₁ and Ns ₂ of the second transformer T2 are wound in the reverse direction, the voltage applied to the gate of the first field effect transistor Q1 and the gate of the second field effect transistor Q2. Are reverse polarity to each other.

That is, when the first field effect transistor Q1 is turned on because the square wave alternating current is applied to the second transformer T2 and the induced voltage is induced in the secondary coil Ns ₁ on one side, the second transformer T2 is turned on. Since the induced voltage is not induced to the other side secondary coil Ns ₂ , the second field effect transistor Q2 is turned off.

On the contrary, when the second field effect transistor Q2 is turned on because the square wave alternating current is applied to the second transformer T2 and the induced voltage is induced in the secondary coil Ns ₂ on the other side, the second transformer T2 is turned on. Since the induced voltage is not induced to the secondary side coil Ns ₁ on one side of the first field effect transistor Q1, the first field effect transistor Q1 is turned off.

Therefore, the two first and second field effect transistors Q1 and Q2 are intermittently applied to the respective gate terminals by an induced voltage induced from the secondary coils Ns ₁ and Ns ₂ of the second transformer T2. Alternately, the on / off operation is repeated.

As described above, the charge and discharge paths of the capacitors C3 and C4 when the first and second field effect transistors Q1 and Q2 alternately perform an on / off operation by the voltage induced by the second transformer T2. Is as follows. That is, when the first field effect transistor Q1 is on and the second field effect transistor Q2 is off, the charge charged in the capacitor C3 is changed from the first field effect transistor to the third transformer via a point. It discharges through the primary coil Np-> b, and charges the capacitor | condenser C4. On the other hand, when the second field effect transistor Q2 is on and the first field effect transistor Q1 is off, the charge charged in the capacitor C4 is changed from the second field effect transistor to the third transformer via point b. Is discharged through the primary coil Np → c of the capacitor, and the capacitor C3 is charged.

Therefore, when the first field effect transistor Q1 is on and the second field effect transistor Q2 is off, the current flowing through the primary coil Np of the third transformer T3 is the second field effect transistor Q2. ) Is on and the first field effect transistor Q1 is off, the current flowing through the primary coil Np of the third transformer T3 is opposite to each other. Therefore, by repeating the above-described operation continuously, the current of the AC square wave flows through the primary coil Np of the third transformer T3.

Even though AC of a square wave is applied to the primary coil Np of the third transformer T3 by the operation described above, in the secondary coil, resonance is caused by the inductance of the secondary coil and the stray capacitance between the coils. Through this output stage, the alternating distortion wave is continuously output. This alternating distortion wave is shown as V _OUT at the bottom of FIG. 5. Here, the alternating distortion wave refers to a waveform in which a square wave having a different vertical width changes its width at a constant period.

The operation of the above-described switching unit 50 and the third transformer T3 which is a boosting transformer will be described in more detail below with reference to FIG. 6.

Here, the boost transformer, which is the third transformer, has a large leakage inductance due to its structural characteristics, and therefore, it is considered that the inductors are connected to each other in series with the primary and secondary coils of the transformer. In the drawing, Llp represents the leakage inductance of the primary coil, Lls represents the leakage inductance of the secondary coil, and Cs represents the stray capacitance of the secondary coil.

In the above circuit configuration, first, when the first field effect transistor Q1 is turned on, between one side terminal of the first field effect transistor Q1 and one side terminal of the primary coil Np of the third transformer T3. Since the Llp connected between the capacitor C3 connected to the other terminal of the first field effect transistor Q1 and the other terminal of the primary coil Np of the third transformer T3 is resonant, the third transformer A waveform resonant current flows in the primary coil Np of T3. Therefore, since the resonant current flows through the primary coil Np of the third transformer T3, the Lls and Cs connected in parallel to the secondary coil Ns of the third transformer T3 again cause secondary resonance, and thus the waveform The secondary voltage of is output.

On the contrary, when the second field effect transistor Q2 is turned on, a capacitor connected between one terminal of the second field effect transistor Q2 and one terminal of the primary coil Np of the third transformer T3. Since the Llp connected between C4 and the other terminal of the second field effect transistor Q2 and the other terminal of the primary coil Np of the third transformer T3 is resonant, the third transformer as described above A waveform resonant current flows in the primary coil Np of T3. Therefore, as described above, the resonant current flows through the secondary coil Np of the third transformer T3, whereby Lls and Cs connected in parallel to the secondary coil Ns of the third transformer T3 are again secondary. The secondary voltage of the sine wave is output by causing resonance.

At this time, when the first field effect transistor Q1 is turned on and the second waveform effect transistor Q2 is turned on when the sign waveform resonant current output from the secondary coil Ns of the third transformer T3 is turned on. The resonant currents of the sine waveforms output from the secondary coil Ns of the three transformers T3 have an antiphase relationship with each other, and the waveforms of these half cycles having an antiphase relationship with each other are combined with each other to form a waveform of a complete cycle.

Therefore, as shown in the lowermost part of FIG. 5, the output terminal V _OUT of the third transformer T3 outputs an alternating distortion wave whose width is changed with a constant period of square waves having different vertical widths.

As described above, the neon tube control circuit according to the present invention generates a voltage having alternating distortion waveforms in which square waves having different vertical widths vary in width by a constant period, and control the neon tube by this control voltage, thereby periodically in the neon tube. Not only can the JB phenomenon in which the contrast is repeated be eliminated, but also the MM phenomenon caused by applying an asymmetrical voltage to the neon tube in order to remove the JB phenomenon in the prior art (the electrode and the end of the neon tube black) is also completely There is a huge effect that can be removed.

In addition, the neon tube control circuit according to the present invention, by eliminating the configuration of generating an asymmetrical voltage by placing electronic elements such as diodes on the output side of the boosting transformer in order to eliminate the JB phenomenon in the prior art, the output side of the boosting transformer This eliminates the concern that the electronic device is destroyed by high pressure.

Claims (3)

The AC input is rectified through the rectifier circuit and input to the switching means, and a part of the AC input is stepped down, rectified into a half-wave rectified pulse current and input to the oscillation circuit part, and the oscillating circuit part alternates based on the half-wave rectified pulse current. A neon tube control circuit configured to generate a distortion wave and input it to the switching means, and output an alternating distortion wave boosted through a boosting transformer connected to an output side of the switching means, wherein the switching means is an output signal of the oscillation circuit portion. A first and second field effect transistors alternately on / off operating based on the " The oscillating circuit section has a square wave generating means having charge and discharge means for accumulating and releasing charges by feeding back part of its output to generate a wave signal by using the half-wave rectified pulse current as an input signal, and charge and discharge of the charge and discharge means. Neon tube control circuit comprising a duty control means for adjusting the speed. The neon tube control circuit according to claim 1, wherein the duty control means for controlling the charge and discharge speed of the charge and discharge means is a resistor connected in parallel between the output terminal of the square wave generating means and the charge and discharge means. The method of claim 1, wherein the charging means has a high charging speed and a low discharge rate when the half-wave rectified pulse wave signal is high level, and a low charging speed and a high discharge rate when the half-wave rectified pulse wave signal is low level. Neon tube control circuit characterized in that.