KR100347303B1 - Device Reducing Acoustic Resonance Phenomena in Metal Halide Lamp - Google Patents

Abstract

Disclosed is an acoustic resonance phenomenon of a metal halide lamp for reducing acoustic resonance occurring when the metal halide lamp is turned on by adding a sinusoidal frequency component to a spherical low frequency to stably light the metal halide lamp. A reduction device.

The device of the present invention accumulates energy in response to the turn-on signal input from the outside, discharges the accumulated energy in response to the turn-off signal input from the outside, and synthesizes a signal of the sinusoidal frequency component with the signal of the spherical low frequency component to produce a metal halide. A lighting signal generating means for outputting a lighting signal of the lamp; a ripple component limiting means for limiting the ripple component of the lighting signal output from the lighting signal generating means; and a lighting signal output from the ripple component limiting means for lighting the metal halide lamp. Checks the energy charged and discharged on the transformer secondary side of the square wave signal generating means and the inverter for generating the current waveform under the condition, and generates a control signal for eliminating the phase difference between the voltage and current on the secondary side of the transformer according to the check result. And control means for controlling the operation state of the lighting signal generating means by using the control signal. As such, to keep the pressure in the discharge tube is constant, the temperature of the electrode end portion is kept constant, the acoustic resonance phenomenon is reduced, and the flicker disappears is possible to prevent the shortening of lamp life.

Description

Device Reducing Acoustic Resonance Phenomena in Metal Halide Lamp

The present invention relates to an apparatus for reducing acoustic resonance of a metal halide lamp.

More specifically, the acoustic resonance phenomenon of the metal halide lamp to reduce the acoustic resonance phenomenon when the metal halide lamp is turned on by adding a sinusoidal frequency component to the spherical low frequency to stably light the metal halide lamp. A reduction device.

In general, metal halide lamps are widely used as illumination lamps in places where color rendering is important because of their excellent color rendering in electrode mode.

When the above-described metal halide lamp is supplied with power for lighting, and a high pressure discharge occurs in the discharge tube of the metal halide lamp, the metal halide lamp generates a natural frequency that may cause resonance with the lamp power frequency.

The above-mentioned natural frequency is generated in the length (Longitudial), radial direction of the radial, azimuthal direction of the diagonal line, the natural frequency is present as a single and complex natural frequency.

When power is supplied to the above-described discharge tube, the gas in the discharge tube is heated by the electric power, and the heated gas is ionized to bring about a change in pressure. At this time, since the gas pressure fluctuates periodically by the square of the input current, that is, the frequency of the electric power, it forms a constant frequency, and the frequency hits the wall surface of the discharge tube.

That is, when the frequency hits the discharge tube wall, a standing wave may occur. When the above-mentioned standing wave coincides with one or more frequencies of the natural frequencies of the discharge tube, the magnitude of the wavelength increases.

As described above, when the size of the wavelength is increased, there is a problem in that the pressure change in the discharge tube is severe and an acoustic resonance which causes the flow of the gas which is an elastic body to be unstable occurs.

Therefore, in order to prevent acoustic resonance occurring when the metal halide lamp is turned on, an acoustic resonance reduction device as shown in FIG. 2 is applied to the lighting device portion of the metal halide lamp.

1 is to implement a lighting device of the metal halide lamp described above, and is configured as a type half bridge inverter. That is, in the lighting device of the metal halide lamp, a rectangular low frequency is generated according to the switching operation of the transistors Q3 and Q4. This spherical low frequency has a problem that it does not completely remove the acoustic resonance phenomenon when the metal halide lamp is turned on.

An object of the present invention is to reduce the acoustic resonance phenomenon generated when the metal halide lamp is turned on by using a method of adding a sinusoidal frequency component to the spherical low frequency to stably light the metal halide lamp to solve the above problems. The present invention provides a device for reducing acoustic resonance of a metal halide lamp.

1 is a circuit diagram for turning on a metal halide lamp according to the prior art;

2 is a circuit diagram for explaining a concept for implementing an apparatus for reducing acoustic resonance when lighting a metal halide lamp according to the present invention;

3 is a circuit diagram embodying an apparatus for reducing acoustic resonance when the metal halide lamp of the present invention is turned on;

4 to 8 are waveform diagrams applied to the present invention.

* Description of Signs of Main Parts of Drawings *

10: lighting signal generating means

20: ripple component limiting means

30: inverter

40: control means

The apparatus of the present invention for achieving the above object accumulates energy in response to the turn-on signal input from the outside, and discharges the accumulated energy in response to the turn-off signal input from the outside to the sinusoidal high frequency component Lighting signal generating means for synthesizing the signal and outputting a lighting signal of the metal halide lamp, ripple component limiting means for limiting the ripple component of the lighting signal output from the lighting signal generating means, and lighting signal output from the ripple component limiting means; Inverter for generating the current waveform under the lighting condition of the metal halide lamp, and the energy charged and discharged on the transformer secondary side of the lighting signal generating means, and the phase difference between the voltage and current on the transformer secondary side is eliminated according to the check result. Generates a control signal for the cycle, the operation state of the lighting signal generating means using the control signal And a control means for control.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a circuit diagram illustrating an apparatus for reducing acoustic resonance when a metal halide lamp is turned on, and FIG. 3 is a circuit diagram illustrating the details of FIG. 2.

As shown, the lighting signal generating means 10 includes a flyback DC-DC converter, accumulates energy in response to the turn-on signal input from the control means 40, and turns the input from the control means 40. A process of discharging the accumulated energy in response to the OFF signal is repeatedly performed to generate and output a lighting signal of the metal halide lamp in which the high frequency ripple component is added to the half-wave rectified DC component.

The ripple component limiting means 20 is composed of a plurality of capacitors, and limits the ripple level of the signal from the above-described lighting signal generating means 10 to a predetermined value or less.

The inverter 30 generates a current waveform based on the lighting condition of the metal halide lamp with the lighting signal output from the ripple component limiting means 20 described above.

The control means 40 checks the energy charged and discharged on the transformer secondary side of the lighting signal generating means 10 described above, and generates a control signal for eliminating the phase difference between the voltage and current on the transformer secondary side according to the check result. By using the control signal described above, the operation state of the lighting signal generating means 10 is controlled.

The operation of the apparatus for reducing acoustic resonance of the metal halide lamp according to the present invention configured as described above will be described in more detail with reference to the accompanying drawings.

4 to 8 are waveform diagrams applied to the present invention.

First, when the transistor Q2 of the lighting signal generating means 10 is turned on in response to the turn-on signal of the control means 40, a voltage having a polarity opposite to that of the primary side is induced on the secondary side of the flyback converter. . Therefore, the voltage induced on the secondary side is cut off by diodes D6 and D7.

As a result, no current flows in the secondary winding of the flyback converter, only current flows in the primary winding, and energy is accumulated in the inductor, and energy charged in the capacitors C5 and C6 is discharged to the load side.

That is, in the above-described state, power is not transferred into the transformer, and all energy supplied to the primary winding is accumulated.

At this time, if the inductance of the transformer primary winding is L _P and the conduction time of the transistor Q2 is t _on , the current flowing through the primary winding is linearly increased to a maximum value at time t = t _on . do.

Therefore, the maximum value i _1P of the primary side current is calculated by the following equation.

Therefore, energy such as Equation 2 is stored in the transformer.

Since the value calculated by Equation 2 is the energy per pulse, the energy as shown in Equation 3 is calculated when f is the frequency per unit time.

On the other hand, when the transistor Q2 is turned off in response to the turn-off control signal of the control means 40, a voltage of opposite polarity is induced in the secondary winding of the transformer than when the transistor Q2 is turned on and conducting. By conducting (D6) and (D7), the energy stored in the transformer is discharged to the output side, and the capacitors C5 and C6 are charged.

As described above, while the conduction and blocking operations of the transistor Q2 are repeatedly performed, the high frequency ripple component is added to the half-wave rectified DC component.

At this time, the size of the high frequency ripple component synthesized to the half-wave rectified DC component as described above is limited by the capacitors C5 and C6, so that the size of the above-described ripple component can be maintained at 10%. ) Is determined.

In addition, when the switch duty ratio of the above-described transistor Q2 is referred to as D, the magnitude of the output voltage is expressed by Equation (4).

In addition, since the transformer provided in the square wave signal generating means 10 can generate not only a unique role such as isolation between input and output, but also a role of an inductor as a filter and a chopped current waveform, the driving current of the metal halide lamp is increased. Converted to square wave in inverter.

As described above, since the square wave signal generating means 10 using the transformer for energy conversion has one switching transistor Q2 and power conversion means having one upper limit output, the BH curve of the transcore is shown in FIG. As described above, when the transistor Q2 is turned on and the transistor Q2 is turned on, the excitation current flows, and the magnetic flux density rises by ΔB as shown in Equation 5 to reach B2.

Here, Ae (cm 2) is the effective cross-sectional area of the core.

In FIG. 4, the B-H curve biased to the maximum magnetic flux density Bm is called a major loop, and the dashed line curve of the actual operating state is called a minor loop.

That is, when the transistor Q2 is turned off, it returns to the point B1 while releasing the accumulated energy. Since the current i ₁ of the primary winding N _P of the transformer is a sawtooth wave, the peak value i _1P at this time is four times the average value of the input current.

At this time, if the power conversion efficiency is η, the peak value i _1P is expressed by Equation 6.

Where V _in is the input voltage and P _o is the output power.

At this time, the inductor L _P of N _P is as shown in Equation 7, and the primary number of turns N _P of the transformer is as shown in Equation 8.

Here, a drawing of the output voltage Vo to the accompanying Figure 2, the current I _O and, when the voltage drop of the diode (D6) (D7) in each of V _F, equal to the size of L and _S Equation (9).

As described above, in order to start the metal halide lamp and reduce the acoustic resonance phenomenon in the lit state, the spherical low frequency generator circuit is implemented as a type half bridge inverter as shown in FIG. 3 to add a sinusoidal frequency component to the spherical low frequency. The back converter can be designed, and the operating principle is a square wave is realized by PWM control of the current source by the switching of transistor Q2 in the flyback DC-DC converter and sent to the half-bridge inverter, and the capacitors C5 and C6. Since the ripple of the power supply is about 10%, the signal of the sinusoidal high frequency component can be synthesized with the signal of the spherical low frequency component.

Referring now to the flyback converter with reference to the waveform diagrams shown in Figures 5-8 of the accompanying drawings, first, as shown in Figure 5A of the accompanying drawings, the current flowing through the primary coil of the transformer is a reference line. This flows up and down, and the reverse electromotive current flows according to the turn-on / turn-off of transistor Q2. FIG. 5B is a waveform diagram of a voltage measured between point D of FIG. 2 and ground.

As a result of the foregoing, when the transistor Q2 shown in FIG. 2 is turned on, a voltage having a polarity opposite to that of the secondary side is induced on the secondary side, so that no current flows in the secondary winding, and only current flows in the primary winding. Energy is stored in the inductor.

On the other hand, the voltage and current waveform of the secondary winding of the transformer provided in the square wave generating means 10, as shown in Figure 6 (A) of the accompanying drawings, the current flows intermittently at point A of Figure 2 of the accompanying drawings As can be seen, when the transistor Q2 of the primary winding is turned off, the current flowing through the two secondary windings alternately knows the flow.

That is, as the transistor Q2 is switched as described above, as shown in FIG. 6B, the tip component and the effective component appear.

As shown in FIG. 2, the energy of the primary coil is transferred to the secondary winding when the transistor Q2 is turned off, and the current of the secondary winding is chopped at a high frequency to the inverter. By sending, the square wave power is supplied to the metal halide lamp.

On the other hand, Figure 7 is a result of measuring the voltage between the points A and C in Figure 2 of the accompanying drawings, (A) is a voltage waveform containing a sinusoidal frequency component in a square wave, (B) is an enlarged sinusoidal frequency component One waveform.

The voltage waveform of FIG. 7A is 120 HZ, the magnitude of the voltage is 76.2V, and the magnitude of the ripple voltage of (B) is 8V.

As described above, it can be seen that the sine frequency component is added to the square wave voltage of 120 Hz at both ends of the capacitor C5, and the size thereof is about 10%.

Finally, Figure 8 shows that the secondary winding of the transformer provided in the square wave signal generating means 10 is divided into two parts, so that the current flows alternately.

As described above, it can be seen that the current waveform in which the current alternately flows is generated by the switching of the transistors Q3 and Q4 of the inverter, and FIG. 8B of FIG. It is a square wave with a frequency of 120HZ as a voltage, a sinusoidal high frequency component is added, and is equal to the voltage between both ends in the capacitor C6.

As a result of the foregoing, when the transistor Q2 included in the primary winding of FIG. 2 is turned off, current flows sequentially in the two secondary windings according to the inverter operation.

As described above, the first embodiment of the present invention selects the metal halide lamp driving frequency as the low frequency band rather than the acoustic resonance frequency band because the acoustic resonance frequency band of the low power lamp having the small discharge tube is biased in the high frequency band, and the low power metal Hal in the second plasma mode. The acoustic resonance phenomenon is reduced by driving the ride lamp with square wave and stable arc discharge. Therefore, it is designed as a type of half-bridge inverter to realize square wave. In the mode of the third electrode, the low-power lamp is added to the square low frequency. The temperature distribution of the electrode is evenly distributed by the skin effect, so that the pressure change in the discharge tube is small, so that the acoustic resonance phenomenon is reduced and the cause of shortening the life of the electrode can be eliminated, thereby extending the life of the metal halide lamp. Provide effect.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below It will be appreciated.

Claims (3)

Energy is accumulated in response to the turn-on signal input from the outside, and the accumulated energy is discharged in response to the turn-off signal input from the outside, and the signal of the sine-frequency component is synthesized by the signal of the spherical low-frequency component to generate the lighting signal of the metal halide lamp. Output signal generating means; Ripple component limiting means for limiting the ripple component of the lighting signal output from the lighting signal generating means; An inverter for generating a current waveform based on a lighting condition of a metal halide lamp from the lighting signal output from the ripple component limiting means; Checking the energy charged and discharged on the transformer secondary side of the lighting signal generating means, and generates a control signal for eliminating the phase difference of the voltage and current of the transformer secondary side in accordance with the check result, and the lighting signal generating means using the control signal Apparatus for reducing the acoustic resonance phenomenon of the metal halide lamp, characterized in that it comprises a control means for controlling the operating state of the. The method of claim 1, wherein the control means, And dividing the lighting signal into N equal parts by the current waveform sensed by the square wave signal generating means, and generating and outputting a control signal corresponding to the N equal parts. According to claim 1, wherein the ripple component limiting means, And the ripple component of the lighting signal output from the lighting signal generating means is limited to within 10%.