KR100585956B1 - A dimming device for the discharge lamp - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminance control device for a discharge lamp, and more particularly, to an illuminance control device for a discharge lamp that can reduce harmonics and eliminate flicker.

The illuminance control device 1 according to the present invention includes a frequency filter unit 20 for filtering only a signal of AC 60 Hz which is more accurate from a signal of AC 60 Hz, and a signal crossing a zero potential point at a frequency on the filtered AC power source. Zero point detection unit 30 for detection, and offset point output unit 40 for generating a signal at a level required by the microprocessor 50 by cutting the state signal from the zero potential detection unit 30 to a predetermined level width ), A microprocessor 50 which receives the constant voltage and zero potential offset points, and performs a frequency width modulation, and receives the frequency width modulated signal from the microprocessor 50 and returns the first feedback amplified signal to a predetermined level. The internal output control unit 60 for processing the control signal and through the internal output control unit 60 through the first feedback amplification signal An external output control unit 70 for supplying a signal of the controlled level, and a low frequency filter unit 80 for removing noise of the signal of the illuminance controlled level output from the external output control unit 70, the zero potential The detector 30 is characterized in that it is composed of optical couplers (PC1, PC2) for detecting the zero potential point receives the AC signal filtered frequency from the frequency filter unit (20).

Illuminance control unit, frequency filter unit, zero potential detection unit, offset point output unit, microprocessor, internal output control unit, external output control unit, low frequency filter unit

Description

Illumination control device for discharge lamps {A DIMMING DEVICE FOR THE DISCHARGE LAMP}

1 shows an application configuration diagram of an illuminance control device for a discharge lamp according to the present invention;

2 shows a block diagram of an illuminance control device for a discharge lamp according to the present invention;

3 shows a circuit diagram of an illuminance control device for a discharge lamp according to the present invention;

4A to 4C show output signal waveforms for voltage frequency response control of the illuminance control device for discharge lamp according to the present invention;

5A and 5D show output signal waveforms according to the prior art.

Explanation of symbols on the main parts of the drawings

One; Illuminance control device 3; ballast

5; Discharge lamp 10; Power supply

20; A frequency filter unit 30; Zero potential detector

40; Offset point output unit 50; Microprocessor

60; An internal output controller 70; External output control unit

80; Low frequency filter unit 90; Data processing unit

100; Display unit / audible unit 110; Fault handling unit

120; Microprocessor protector 130; Remote controller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminance control device for a discharge lamp, and more particularly, to an illuminance control device for a discharge lamp that can reduce harmonics and eliminate flicker.

Conventional illumination control for a lamp uses a voltage current control, that is, a control according to the change in the lamp load. However, the illuminance control of the discharge lamp, due to the characteristics of the discharge lamp, burns the gas in the discharge lamp to emit hot electrons to indicate the brightness of the light. Since the load change has a negative resistance characteristic, the load change cannot be easily changed during illumination control. It was not easy to control the power supply so that the tube voltage current was kept constant.

Therefore, when controlling the illuminance of the discharge lamp, a separate illuminance control device is required, and various illuminance control techniques have been developed. Illuminance control technology of such a discharge lamp can be classified as follows. First, the illuminance control was performed by converting the AC power supplied to the ballast necessary for lighting the discharge lamp by converting the DC signal level at the FET oscillator inside the ballast. Secondly, while the conventional ballast is used as it is, the rated voltage input to the ballast is controlled by varying the supply input voltage at the ballast using a slick or the like to perform illuminance control. Third, the illumination control method by the microprocessor is to use the zero-crossing method, which uses the zero-crossing pointer to modify the AC signal waveform by PWM modulation or the like in the microprocessor to convert this signal. Various methods such as voltage control, current control, and phase control were used. In this case, the first and second methods may have a narrow width of the illuminance control, whereas the third method may realize a wide range of the illuminance control. In particular, the chopping function by the high-speed switching of the input waveform is performed during the voltage current control through the phase control, wherein the analog signal using the chopping function is controlled. However, harmonics are inevitably generated based on the control point of the signal when controlling the illuminance by the chopping function.

Such harmonics can seriously impair existing ballasts and discharge lamps. In particular, discharge lamps may cause malfunctions due to the change of phase angle, which causes problems such as power factor drop, noise generation of harmonic filters, and radio interference. Is generated from In addition, this harmonic causes problems such as insulation breakdown of the power factor correction capacitor used in the ballast and overheating of the choke coil, which affects the lifespan and stability of the ballast. There is a problem of generating noise due to electromagnetic induction obstacles when operating a communication device (see FIGS. 5A to 5D).

Figure 5a is applied to a method of turning on / off the output voltage / current by making the input AC signal constant in a general phase control method, the signal flow is not easy in the control interval when controlling the voltage / current, the voltage control point There is a problem with serious harmonics.

5B to 5D show that the intensity of the illuminance control is widened by gradually increasing the signal phase angle of the output through the pulse width modulation control of the phase of the input signal in the above-described control scheme. There is a problem in that harmonics accompany the flicker phenomenon such as discharge.

Accordingly, it is an object of the present invention to provide an illuminance control device for a discharge lamp that can reduce harmonics of waveforms generated during phase control.

Another object of the present invention is to provide an illuminance control device for a discharge lamp that does not affect the life and stability of a ballast by reducing harmonics of waveforms generated during phase control.

Still another object of the present invention is to provide an illuminance control device for a discharge lamp that can solve a flicker phenomenon such as a discharge lamp caused by voltage / current instability.

Illumination control device according to the present invention for achieving the above object

A frequency filter unit for filtering only a more accurate AC 60 Hz signal from an AC 60 Hz signal, a zero potential detector for detecting a signal crossing a zero potential point at a frequency on the filtered AC power source, and a zero potential detector. An offset point output unit for generating a signal at a level required by the microprocessor by cutting a state signal into a width of a predetermined level, a microprocessor which receives a constant voltage and a zero potential offset point and performs frequency width modulation, and from the microprocessor An internal output control unit for receiving a frequency width modulated signal and processing the first feedback amplified signal back to a predetermined level, and a signal having an illuminance controlled level to the output side using the primary feedback amplified signal through the internal output control unit. An external output control unit for supplying the above A low frequency filter unit for removing noise of the signal of the illuminance controlled level output from the sub output control unit, wherein the zero potential detection unit is composed of an optical coupler for receiving a frequency filtered AC signal from the frequency filter unit to detect the zero potential point It features.

In addition, the collector of the optocoupler is connected to the VCC generated by the constant voltage generator, the emitter of the optocoupler is characterized in that connected by a wire-OR (Wire-OR).

Hereinafter, the most preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the technical idea of the present invention. .

1 shows an application configuration diagram of an illuminance control device for a discharge lamp according to the present invention, which is composed of an illuminance control device 1, a ballast 3, and a discharge lamp 5. Here, the illuminance control device 1 is described in detail below, and the ballast 3 and the discharge lamp 5 are generally well known techniques and will be omitted below.

2 shows a block diagram of an illuminance control device for a discharge lamp according to the present invention, and FIG. 3 shows a circuit diagram of an illuminance control device for a discharge lamp according to the present invention.

2 and 3, the illumination control device 1 according to the present invention includes a power supply unit 10, a frequency filter unit 20, a zero potential detection unit 30, an offset point output unit 40, and a microcontroller. Processor 50, internal output control unit 60, external output control unit 70, low frequency filter unit 80, data processing unit 90, failure processing unit 100, display unit / audible unit 110, microprocessor protection unit 120 and remote controller 130.

The power supply unit 10 includes a power input unit 12 for converting an AC voltage 220V applied from the input ports IN1 and IN2 into an AC voltage 9V, and an AC voltage 9V converted by the power input unit 12 to a DC voltage 9V. And a constant voltage generator 16 for generating the DC voltage 9V converted by the voltage converter 14 into a DC voltage VCC at a constant voltage level.

The power input unit 12 includes a thermistor D1, capacitors C1 and C10, an inductor L1, and a transformer T1. The power input unit 12 protects the illuminance control device 1 from the input power through the lightning protection thermistor D1 for the power supplied from the input ports IN1 and IN2 to the ballast 3 and the discharge lamp 5. It also receives power protected from the input power and filters the noise (C1 and C10 are connected in parallel and C10 and L1 are connected in series to act as a noise filter) and generates power for the internal circuit of the illumination control device (1). Means.

The voltage converter 14 is constituted by a bridge circuit having diodes D2-D5 connected to the output side of the transformer T1.

The constant voltage generator 16 includes a constant voltage regulator U1 for generating a constant voltage / current and capacitors C6 to C9 connected to the regulator. The constant voltage generator 16 uses a DC power supply through a bridge circuit having diodes D2 to D5 to convert the DC constant voltage to the zero potential detector 30 and the offset point output unit 40 regardless of the ripple and noise of the input power. ), The microprocessor 50, the internal / external output control units 60 and 70, the data processing unit 90, and the display unit / audible unit 110. The constant voltage generator 16 provides a constant voltage to reduce harmonics and remove flicker. Here, since the device configuration of the power supply unit 10 is generally known, some descriptions thereof will be omitted.

The frequency filter unit 20 is composed of a resistor (R1) and capacitors (C2 to C4). The resistor R1 and the capacitors C2 to C4 are connected in series and parallel. The output side of the transformer T1 of the power input unit 12 and the capacitors C2 and C3 are connected in series, the capacitors C4 and C5 are connected in series, and the frequency filter unit 20 connected in parallel with the resistor R1 is an external power input. This is for detecting the frequency state (in phase) of the power supply synchronized with the AC power supply unit 12 and is a means for obtaining an accurate AC 60hz frequency using the power converted into AC 9V through the transformer T1 of the power input unit 12. In addition, the frequency filter unit 20 is capable of detecting the zero potential in the in-phase frequency state with the AC 60hz power supplied from the input ports IN1 and IN2.

The zero potential detection unit 30 is composed of optical couplers (PC1, PC2) for detecting the zero potential point receives an AC signal filtered frequency from the frequency filter unit (20). A signal connected to the other end of the resistor R1 of the frequency filter unit 20 is connected to the anode of the optical coupler PC1 and the cathode of the optical coupler PC2, and the collector C of the optical couplers PC1 and PC2 is a constant voltage. It is connected to the VCC generated by the generation unit 16 and the emitter (E) of the optical coupler (PC1, PC2) is connected by a wire-OR (Wire-OR). Further, the emitter E of the optocoupler PC1 is connected to the other end of the resistor R2 of the offset point detector 40, and the emitter E of the optocoupler PC2 is the resistance of the offset point detector 40. It is connected to the other end of (R3). The zero potential detector 30 controls the + -side waveform on the frequency figure of the input power at the in-phase frequency of the frequency-filtered AC power by the optical coupler PC1 and the -side waveform by the optical coupler PC2. A zero-phase waveform is detected by extracting a signal based on a voltage point coinciding with a voltage point of 0V of a voltage.

The offset point output unit 40 is composed of a transistor Q1 and resistors R2 to R4. The offset point output unit 40 performs a function of detecting an offset point signal for creating a signal level and width required by the microprocessor 50 for the zero potential signal level detected from the zero potential detection unit 30. Referring to the connection relationship between the offset point output unit 40, the collector C of the transistor Q1 is grounded through the resistor R4, and the image of the zero potential detector 30 is already grounded through the ground and the resistor R3. Is connected to the other end of the resistor R2 which is wire-ORed to the rotor E. Base B is connected to one end of resistor R2 and emitter E is connected to VCC. The resistor R2 and the resistor R3 serve to hold the bias level of the transistor Q1, and the resistor R4 is used to determine the output level of the offset point detector 40. The offset point output unit 40 generates the offset pointer pulse signal at a level required by the microprocessor 50 by cutting the signal of the state level emitted from the zero potential detection unit 30 in the above configuration to a predetermined width. It is connected to the input / output signal connection CON6 of the processor 50 and provides an input signal of the microprocessor 50.

The microprocessor 50 receives the above-described constant voltage and zero potential offset point, performs frequency-width pulse modulation (FWM), and desired illumination control, fault status display, and circuit operation by manual / remote control. It is a means to instruct audible hearing about the disability. The microprocessor 50 also includes a microprocessor protector 120 that protects the instantaneous voltage / current of the microprocessor 50.

In addition, the microprocessor 50 controls the flicker phenomenon through the pulse width modulation using the power source frequency. The microprocessor 50 is programmed to actively respond to sudden changes in illuminance by receiving the output signal of the internal output controller 60, and reflects the load resistance value of the discharge lamp, which is the biggest problem of the flicker phenomenon, in the program. By performing FWM on user command execution, a function of eliminating the flicker phenomenon that is often generated during low-level illumination control is performed.

The internal output controller 60 is composed of a transistor Q2 connected to the output side of the microprocessor 50. The collector C of the transistor Q2 is grounded, the base B is connected to the input / output signal connection CON6 of the microprocessor 50 and connected to the output signal of the microprocessor 50, and the emitter E ) Is connected to the external output control unit 70. The internal output controller 60 receives a pulse width modulated (FWM) signal applied with a frequency from the microprocessor 50, amplifies and inverts the signal to a predetermined level, and outputs a signal required by the external output controller 70. And provide the result to the microprocessor 50.

The external output control unit 70 is composed of optical isolators (MOC1, MOC2), resistors (R5, R6, R7, R8, R9, R10), capacitors (C11, C12), diodes (D6) and triacs (DB1). do. The optical isolators MOC1 and MOC2 are connected in series, and the optical isolator MOC1 is connected in parallel with the resistor R6, which is connected to one end of the resistor R8 to the anode A1 of the triac DB1 and the resistor ( Is connected to the other end of R8). The optical isolator MOC2 is connected in parallel with the resistor R7, which is connected to one end of the resistor R10 and connected to the anode A2 of the triac DB1 and the other end of the resistor R10. The signal processed by the internal output controller 60 is connected to the cathode of the optical isolator MOC2, which is connected to the anode of the diode D6, and the cathode of the diode D6 is connected to the VCC through a resistor R5, It is connected to the anode of the optical isolator MOC1. The resistor R5 is used as a bias value of the optical isolator MOC1. The gate of the triac DB1 is connected to the optical isolator MOC2 and one end of the parallel connection resistor R7, and the anode A2 of the triac DB1 is connected to the other end of the resistor R10 to connect the capacitor C11. Is connected in series with one end of the resistor R9 connected in series with the capacitor C12, the other end of the capacitor C12 and the other end of the capacitor C11 are connected with the anode A1 of the triac DB1, The other end of the resistor R8 is connected to the optical isolator (MOC1). This is connected to the other end of the capacitor C13 constituting the low frequency filter portion 80 of the output ports OUT1 and OUT2, and becomes one output signal of the illuminance control device.

In addition, the external output control unit 70 is a means for supplying a smooth illumination control output power to the output side by using the inverted and amplified signal through the internal output control unit 60 by feedback. The external output control unit 70 inputs a level-converted amplified signal from the internal output control unit 60 to the input signal of the external output control unit 70 to the input side cathodes of the two irregular phase optical isolators MOC2, and the diode ( D3) is input to the anode of the optical isolator MOC1 for level processing of the + side signal waveform of the AC power frequency signal, and is operated in series with the cathode of the optical isolator MOC1 and the optical isolator MOC2 and the anode. Illuminance control is possible for the signal of the whole frequency range of AC 60Hz. In this case, the bias resistors R6 and R7 are connected in parallel to the main signal output side of the light receiving unit of the light isolators MOC1 and MOC2 to control the start and end points of the positive and negative waveforms of the AC 60 Hz frequency signal. do.

The controlled signal delivers the appropriate voltage through the resistors R8 and R10 to the anodes A1 and A2 of the triac DB1 of the external output control unit 70. In addition, the light receiver main signal output signal for the final signal of the optical isolator (MOC2) is a gate of the triac DB1 is directly connected to facilitate the current / voltage control for the harmonic removal of the illumination control device (1). The output controlled signal is connected between the two anodes of the triac DB1 and the resistor R9 in series with the capacitor C11 before going to the final output voltage through the anode A1 of the triac DB1. Is connected in parallel to remove the breakage of the current at the time of on / off of the digital signal due to the chopping phenomenon generated when the frequency width modulation to the digital signal from the microprocessor 50 according to the current control of the triac DB1, It acts as a harmonic filter that blocks the harmonics of the final output voltage.

The signal of the width modulation of the frequency controlled by the microprocessor 50 facilitates the control of the waveform +/- both side bands of the AC signal simultaneously through the optical isolators MOC1 and MOC2, and this is the gate input of the triac DB1. By controlling the voltage and current, the AC 60hz signal, which is an analog signal, is continuously controlled. Therefore, serious harmonic problems caused by discharge lamps do not occur when the microprocessor 50 controls the illuminance. In addition, since the discharge lamp is controlled so that the minimum tube voltage current required for gas activation of the discharge lamp is not changed rapidly, the flicker phenomenon of the discharge lamp does not occur.

The low frequency filter unit 80 includes an inductor L2 and a capacitor C13. The inductor L2 and the capacitor C13 are connected in series. This configuration eliminates the low and high frequencies generated from the final output voltage signal sent to the ballast 3 through the output ports OUT1 and OUT2 from the illuminance controlled level signal from the external output controller 70, and harmonics. It serves as a second noise filter to eliminate the occurrence of. In addition, the low frequency filter unit 80 is not shown in Figures 2 and 3, but is connected to the ballast (3).

The data processor 90 is a means for allowing the microprocessor 50 to perform a state of illuminance desired by the user manually or by the remote controller 130. Here, since the remote controller is a general configuration, description thereof will be omitted.

The failure processing unit 100 serves to directly supply external input power to the external control output unit 70, for example, when a component of the illumination control device 1 has failed.

The display / audible part 110 represents a state of illuminance manually or remotely required by the microprocessor 50 and occurs in a self failure state of the microprocessor 50 or a peripheral circuit controlled by the microprocessor 50. It is a means of indicating the status of the fault and inform the buzzer (not shown).

Here, the circuit configurations of the microprocessor 50, the data processor 90, the fault processor 110, the display / audible part 100, and the microprocessor protector 120 are well known, and thus the circuit configurations of FIG. Not shown.

4A to 4C show output signal waveforms for voltage frequency response control of the illuminance control device for discharge lamp according to the present invention. 4A is an output waveform of a state before illuminance control under a rated voltage / frequency state. 4B and 4C are a technique of distributing a voltage level to a control frequency change width of a 60 Hz signal, and showing an amplitude of change of 2 n steps based on n volts per step of an illuminance control command, and clearly showing an effect of illuminance control. to be. The illumination control device 1 according to the present invention can solve the problem that harmonics are generated by distorting the waveform of the input frequency in the conventional phase control, as shown in FIGS. Solving the harmonic problem without damaging the input voltage waveform in performing the control, and by the characteristics of the discharge lamp, the ballast initially uses a high-voltage discharge voltage and maintains the tube voltage current of the discharge lamp, preheating in the condition that the illumination control is performed Illumination control of the actual discharge lamp by voltage / current can be effectively implemented by gradually lowering the voltage provided to the ballast or raising the maximum rated voltage while maintaining the minimum tube current of the discharge lamp.

In addition, FIG. 4B shows an internal output controller while the microprocessor 50 receives the 30% illuminance control from the data processor 90 and outputs a control signal for a frequency range modulation using a zero potential offset signal. At 60, the inverted amplification is transferred to the external output controller 70 and the microprocessor 50 is fed back to reflect the state of the external output control point, thereby lowering the voltage level by 30% and maintaining the current. The width of the upper and lower bands of the 60 Hz signal is gradually controlled and output. In this figure, the level control of the voltage current is made without interruption of the signal flow until the control point is completed.

In addition, FIG. 4C shows that when 70% of illuminance control is requested from the data processing unit 90, the microprocessor 50 receives the same and outputs a control signal of a frequency width modulation as much as a control range by using a zero potential offset signal. At 60, the inverted amplification is transmitted to the external output controller 70, and the microprocessor 50 feedbacks and outputs the state of the external output control point, thereby lowering the level of the voltage by 70% and maintaining the current. The width of the upper and lower bands of the 60 Hz signal is gradually controlled and output. In this figure, the level control of the voltage current is made without interruption of the signal flow until the control point is completed.

The operation of the illuminance control device 1 having the above structure will be described in detail as follows.

2 and 3, the illuminance control device 1 according to the present invention receives the AC 60hz phase power supplied from the outside from the input port (IN1, IN2) and passes through the thermistor (D1).

Then, the inductor L1 connected in series with the capacitor C10 to the signal passing through the thermistor D1 is connected in parallel with the capacitor C2 to become the noise filter circuit of the AC 60 Hz signal, and the signal passed through the noise filter circuit. Passes through the transformer T1. The AC 220V 60Hz signal is converted into an AC 9V 60Hz signal through the transformer T1, and the diodes D2 to D5 convert the AC 9V 60Hz signal into a DC signal to rectify the AC signal.

Then, the constant voltage regulator U1 generates the rectified signal as a constant voltage VCC power source using the ripple cancellation capacitors C6 and C7 and the constant voltage filter capacitors C8 and C9. At this time, the generated constant voltage is provided to the constant voltage VCC power supply required by the microprocessor 50, and also to the zero potential detection unit 30, the offset point output unit 40, the internal output control unit 60 and the external output control unit 70. Supplied.

In addition, the AC 9V 60Hz signal generated through the transformer T1 is a frequency filtered signal using the resistor R1 and the capacitors C2 to C5 and is corrected by the optocouplers PC1 and PC2 of the zero potential detection unit 30. Allow zero potential detection. At this time, the frequency filtered signal is provided at the same level in phase to the cathode of the optical coupler PC1 and the anode of the optical coupler PC2 of the zero potential detection unit. Through this signal, the optocouplers PC1 and PC2 find the zero potential point by judging the state of the AC 60Hz signal crest. The resistors R2 to R4 and the transistor Q1 convert the zero potential signal into an offset point signal so that the microprocessor 50 easily processes the detected zero potential signal. The generated offset point signal is provided as an input signal of the micro process.

The microprocessor 50 receives constant voltage power supply through the constant voltage generation unit 16 and information about the offset point signal of the zero potential point through the offset point detection unit 40, and is requested from the data processing unit 90. According to the control signal, the illumination control is easily processed through the FWM modulation, and control is performed to display / hear the failure or program error.

In addition, the microprocessor 50 connects the output signal performed according to the request of the data processor 90 through the base of the transistor Q2 and inverts and amplifies it through the emitter signal of the transistor Q2 to provide the optical isolator MOC2. The upper band signal of the alternating current frequency is connected to the cathode, and connected to the anode of the optical isolator MOC1 through the diode D6 to process the lower band signal of the alternating frequency to simultaneously control the AC 60 Hz full-band signal. At this time, the internal output control unit 60 feeds back the emitter output signal of the transistor Q2 to the microprocessor 50 to prevent a sudden change in the control signal flow.

In addition, by parallelly connecting bias resistors R6 and R7 to the main signal outputs of the light receiving sections of the two optical isolators MOC1 and MOC2, the start point and the end point of the upper or lower band signal level of the AC 60 Hz signal are equally controlled. do. This signal is then connected via the resistors R8 and R10 to the anodes A1 and A2 of the triac DB1, which controls the value of the current, so as to control the voltage level. Is controlled by controlling the flow of current and controlling the voltage / current level of the output frequency control signal.

In addition, the capacitor C11 between the anodes A1 and A2 of the triac DB1 and the capacitor C12 connected in series with the resistor R9 are connected in parallel to perform a first order high frequency filter function. Likewise, the flicker phenomenon was eliminated by preventing sudden changes in harmonics and tube voltage currents, and a low frequency filter in which an inductor (L2) and a capacitor (C13) were connected in series at both ends of the final output ports (OUT1, OUT2). Parallel connection achieves harmonic control with no harmonics. With this configuration, the illuminance controlled signal is provided to the power supply of the ballast 3 through the output ports OUT1 and OUT2.

The present invention described above is capable of various substitutions, modifications, and changes without departing from the technical spirit of the present invention for those skilled in the art to which the present invention pertains. It is not limited.

The illuminance control device for discharge lamp according to the present invention as described above reduces the harmonics of the waveform generated during phase control without affecting the life and stability of the ballast, and also prevents flicker of discharge lamps due to voltage / current instability. It can work.

Claims (3)

A frequency filter unit 20 for filtering only a more accurate AC 60Hz signal from the AC 60Hz signal, A zero potential detection unit 30 for detecting a signal crossing a zero potential point at the frequency of the filtered AC power source; An offset point output unit 40 for generating a signal at a level required by the microprocessor 50 by cutting the state signal from the zero potential detection unit 30 to a predetermined level width; A microprocessor 50 receiving the constant voltage and zero potential offset points and performing frequency width modulation; An internal output controller 60 for receiving the frequency-modulated signal from the microprocessor 50 and processing the first feedback amplified signal back to a predetermined level; An external output control unit 70 for supplying a signal having an illuminance controlled level to the output side by using the first feedback amplification signal through the internal output control unit 60; It includes a low frequency filter unit 80 for removing noise of the signal of the illuminance controlled level output from the external output control unit 70,  The zero potential detection unit 30 is an illumination light intensity control device for a discharge lamp, characterized in that consisting of optical couplers (PC1, PC2) for receiving a frequency-filtered AC signal from the frequency filter unit 20 to detect the zero potential point. The method of claim 1, The collector C of the optocouplers PC1 and PC2 is connected to the VCC generated by the constant voltage generator 16 and the emitter E of the optocouplers PC1 and PC2 is connected by wire-OR. Illumination control device for discharge lamps. The method of claim 1, The external output control unit 70 is composed of optical isolators (MOC1, MOC2), resistors (R5, R6, R7, R8, R9, R10), capacitors (C11, C12), diodes (D6) and triacs (DB1). Wherein the optical isolators MOC1 and MOC2 are connected in series, and the optical isolator MOC1 is connected in parallel with the resistor R6, which is connected with one end of the resistor R8 to the anode A1 of the triac DB1. And the other end of the resistor R8, and the optical isolator MOC2 is connected in parallel with the resistor R7, which is connected to one end of the resistor R10 to the anode A2 and the resistor R10 of the triac DB1. Connected to the other end of the signal, and the signal processed by the internal output controller 60 is connected to the cathode of the optical isolator (MOC2), which is connected to the anode of the diode (D6) and the cathode of the diode (D6) is connected to the resistor (R5) It is connected to the VCC through, and connected to the anode of the optical isolator (MOC1), the resistor (R5) is the anode of the optical isolator (MOC1) The node of the triac DB1 is connected to the optical isolator MOC2 and one end of the parallel connection resistor R7, and the anode A2 of the triac DB1 is connected to the other end of the resistor R10. And connected in series with the capacitor (C11), connected to one end of the resistor (R9) connected in series with the capacitor (C12), the other end of the capacitor (C12) and the anode (A1) of the triac DB1, Illumination control device for discharge lamp, characterized in that connected to the other end of the resistor (R8) connected to the optical isolator (MOC1).

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