JP2007200781A - High-pressure discharge lamp lighting device and lighting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To adjust a lamp power, as well as to achieve low withstand voltage and reduced size of circuit components to be used. <P>SOLUTION: A high-pressure discharge lamp lighting device includes an inverter circuit 16 which performs a high-frequency lighting operation for a high-pressure discharge lamp 18 by applying a DC voltage from a DC power supply circuit 12 and driving two switch elements Q2 and Q3 for switching on/off alternately, a lamp voltage detector circuit 20 for detecting a lamp voltage of the high-pressure discharge lamp, an acoustic resonance determination means 151 which determines the presence or absence of the acoustic resonance using the lamp voltage detected by the lamp voltage detector circuit 20, a frequency control means 152 which controls a switching frequency of the inverter circuit 16 to be a non-acoustic resonance frequency in accordance with a result of determination for the presence or absence of the acoustic resonance from the acoustic resonance determination means, and a lamp power adjustment means 153 which adjusts the lamp power by changing the on-duty of the elements Q2 and Q3 at a cycle longer than a switching cycle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high-pressure discharge lamp lighting device for lighting a high-pressure discharge lamp at a high frequency, and an illumination device using the high-pressure discharge lamp lighting device.

  When a high pressure discharge lamp is turned on at high frequency, an acoustic resonance phenomenon occurs and the lighting state becomes unstable. Therefore, in a high pressure discharge lamp lighting device that outputs high frequency power using an inverter circuit, the switching frequency of the switch element is set to the non-resonant frequency. The stable lighting state of the high-pressure discharge lamp is secured by adjusting to the belt.

In a high pressure discharge lamp lighting device that performs such control, since the switching frequency of the inverter circuit is determined, the lamp power cannot be adjusted by changing the switching frequency. In view of this, there is one that adjusts the lamp power by controlling the output voltage of the DC power supply in a state where the switching frequency of the inverter circuit is adjusted to the non-resonant frequency band (see, for example, Patent Document 1).
JP 2004-235033 A

  However, in the case of adjusting the lamp power by controlling the output voltage of the DC power supply, the withstand voltage of each circuit component must be set in accordance with the state in which the output voltage is the highest, and thus the circuit component to be used There is a problem that the pressure is increased, resulting in an increase in size of the device and an increase in cost.

  The present invention enables high-voltage lighting of a high-pressure discharge lamp with the switching frequency of the inverter means set to a non-resonant frequency band, and can adjust the lamp power and reduce the withstand voltage of the circuit components to be used. There are provided a high pressure discharge lamp lighting device and an illuminating device that can be reduced in size and cost.

  According to the first aspect of the present invention, a DC voltage is inputted from the DC power supply means, and at least two switch elements are alternately turned on / off to drive the inverter means for high-frequency lighting of the high pressure discharge lamp, and the lamp voltage of the high pressure discharge lamp is detected. A ramp voltage detecting means for determining the presence or absence of acoustic resonance using the lamp voltage detected by the lamp voltage detecting means, and an inverter based on the determination of the presence or absence of acoustic resonance by the acoustic resonance determining means A frequency control means for controlling the switching frequency of the means to be a non-acoustic resonance frequency, and a lamp power adjusting means for adjusting the lamp power by changing the on-duty of switching of the switch element in a cycle longer than the switching cycle. It is in the high pressure discharge lamp lighting device.

  As the high-pressure discharge lamp, a mercury lamp, a metal halide lamp, a high-pressure sodium lamp, or the like is used. A ceramic discharge lamp using an alumina tube as the arc tube is also used.

  As the DC power supply means, for example, a full-wave rectifier circuit that rectifies an AC power supply voltage and a boost chopper circuit that generates a DC voltage boosted by inputting an output voltage of the rectifier circuit is used. Note that other boosting methods may be used.

  There are various types of inverter means such as a half bridge type and a full bridge type. For example, a half-bridge type high-frequency inverter circuit having two switching elements that are connected in series and alternately turned on and off and an LC resonance circuit controls the switching frequency of the inverter circuit by the control means, and the high-frequency output from the inverter circuit is high-voltage By applying the voltage to both ends of the discharge lamp, the high pressure discharge lamp is turned on at high frequency.

  The lamp voltage detecting means detects a high-frequency voltage at both ends of the high-pressure discharge lamp, and is used for detecting the lamp voltage in a stable lighting state after starting the lamp. Moreover, since the lamp voltage fluctuates when an acoustic resonance phenomenon occurs, it is also used for determining whether or not acoustic resonance has occurred.

  Further, the lamp power adjusting means of the invention according to claim 2 is configured to continuously change the on-duty.

  According to a third aspect of the present invention, there is provided a high-pressure discharge lamp lighting device according to the first or second aspect, a high-pressure discharge lamp that is lit by the high-pressure discharge lamp lighting device, and an instrument body equipped with the high-pressure discharge lamp. It is in the provided lighting device.

According to the present invention, the lamp power is adjusted by changing the on-duty of the switching of the switching element at a cycle longer than the switching cycle in the high-frequency discharge lamp that operates at a high frequency with the switching frequency of the inverter means set to the non-resonant frequency band. Therefore, it is possible to adjust the lamp power and to reduce the withstand voltage of the circuit components to be used, thereby reducing the size and cost of the device, and the high pressure discharge lamp lighting device and lighting device. Can be provided.
In addition, according to the present invention, it is possible to provide a high pressure discharge lamp lighting device and a lighting device that can adjust the lamp power more accurately.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a diagram showing a circuit configuration of a high pressure discharge lamp lighting device. This high pressure discharge lamp lighting device is connected to an AC power source AC as a DC power source means via a noise filter circuit 11 comprising capacitors C1, C2 and a transformer T1. A DC power supply circuit 12 is connected.

  The DC power supply circuit 12 includes a full-wave rectifier circuit 13 composed of a diode bridge and a step-up chopper circuit 14, and the full-wave rectification is performed on the alternating current from the noise filter circuit 11 by the full-wave rectifier circuit 13. A high frequency component is removed by a high frequency component removing capacitor C 3 connected in parallel to the output terminal of the rectifier circuit 13, and then supplied to the step-up chopper circuit 14. A control circuit 15 is connected to the output terminal of the full-wave rectifier circuit 13.

  The step-up chopper circuit 14 is provided with a transformer T2, a switching element Q1 made of a MOS FET, and a smoothing capacitor C4. The positive terminal of the capacitor C3 is connected to the switching element Q1 via the primary winding T2p of the transformer T2. In addition to being connected to the drain terminal, the diode D1 is connected to one end of the smoothing capacitor C4 via the forward polarity direction, the negative terminal of the capacitor C3 is connected to the other end of the smoothing capacitor C4, and a resistor R1 is connected in series to the source terminal of the switch element Q1.

  The secondary winding T2s of the transformer T2 has one end connected to the negative terminal of the capacitor C3, the other end connected to the control circuit 15, and the diode D2 connected to one end of the smoothing capacitor C5 via the forward polarity direction. is doing. The other end of the smoothing capacitor C5 is connected to the negative terminal of the capacitor C3. The connection point between the diode D2 and the smoothing capacitor C5 is connected to the positive side of the output terminal of the full-wave rectifier circuit 13 through a resistor R2 in series.

The control circuit 15 receives a voltage value output to the smoothing capacitor C5, a current value flowing from the switch element Q1 to the resistor R1, and a voltage value output to the smoothing capacitor C4.
The step-up chopper circuit 14 outputs a DC voltage VDC boosted across the smoothing capacitor C4 and supplies it to an inverter circuit 16 as inverter means.

  The inverter circuit 16 includes a switch element Q2, Q3 composed of a pair of MOS FETs connected in series, a resistor R3 connected in series to the source terminal of the switch element Q3, and a series of the switch element Q3 and the resistor R3. The circuit is composed of an LC resonance circuit 17 in which a DC cut capacitor C6 is connected in parallel to the circuit in series. The LC resonance circuit 17 is formed by a series circuit of a resonance inductor L1 and a resonance capacitor C7.

  A high pressure discharge lamp 18 is connected to both ends of a resonance capacitor C7 which is an output end of the inverter circuit 16. The current flowing through the switching element Q3 of the inverter circuit 16 is detected by the current detection circuit 19, and the detection signal is supplied to the control circuit 15. The current detection circuit 19 connects a capacitor C8 in parallel to the resistor R3 through a resistor R4 in series, and outputs a detection signal from both ends of the capacitor C8.

  The lamp voltage of the high-pressure discharge lamp 18 is detected by a lamp voltage detection circuit 20 which is lamp voltage detection means. The lamp voltage detection circuit 20 has a series circuit of resistors R5 and R6 connected in parallel between both ends of the high-pressure discharge lamp 18, and a connection point between the resistors R5 and R6 is connected to a diode via a capacitor C9. The cathode terminal of D3 and the anode terminal of diode D4 are connected. The cathode terminal of the diode D4 is connected to one end of a capacitor C10, and the anode terminal of the diode D3 and the other end of the capacitor C10 are connected to the other end of the resistor R6. The capacitors C9 and C10 and the diodes D3 and D4 form a voltage doubler rectifier circuit, and a lamp voltage detection signal is extracted from both ends of the capacitor C10 and supplied to the control circuit 15.

  The control circuit 15 boosts the input voltage to the DC voltage VDC by controlling the switching frequency and on-duty of the switch element Q1 of the boost chopper circuit 14. The step-up chopper circuit 14 stores energy in the primary winding T2p of the transformer T2 when the switch element Q1 is on, and supplies the diode D1 with energy stored in the primary winding T2p when the switch element Q1 is off. Is discharged to the smoothing capacitor C4, and the boosted voltage is charged to the smoothing capacitor C4.

  In addition, the control circuit 15 uses the lamp voltage detected by the lamp voltage detection circuit 20 to determine the presence or absence of acoustic resonance. The acoustic resonance determination means 151 determines whether or not acoustic resonance exists. Based on the frequency control means 152 for controlling the switching frequency of the inverter circuit 16 to a non-acoustic resonance frequency and the lamp power adjusting means for adjusting the lamp power by controlling the on-duty of switching of the switching elements Q2 and Q3 of the inverter circuit 16. 153 is provided.

  That is, the control circuit 15 alternately drives the pair of switch elements Q2 and Q3 of the inverter circuit 16 with a short period of high frequency by the frequency control means 152, and sets the switch elements Q2 and Q3 by the lamp power adjustment means 153. The on-duty is fixed to 50% at the time of starting the lamp, is changed at a low frequency with a long period when the lamp is lit, and the on-duty of each of the switching elements Q2 and Q3 is controlled to be inverted. The high frequency in this field indicates a frequency exceeding 1 kHz, and is usually driven at a frequency in the range of 40 kHz to 50 kHz. The low frequency in this case indicates a frequency of 1 kHz or less, and the on-duty is changed at a low frequency of about 100 Hz here.

  When the acoustic resonance phenomenon occurs, the lamp voltage rises as compared with non-acoustic resonance. Therefore, the acoustic resonance determining means 151 of the control circuit 15 sets a reference voltage V1 for determining acoustic resonance, as shown in FIG. In step S1, it is determined whether or not the detected lamp voltage is equal to or higher than the reference voltage V1, and if it is equal to or higher than the reference voltage V1, occurrence of an acoustic resonance phenomenon is determined in step S2, and less than the reference voltage V1. If so, the non-occurrence of the acoustic resonance phenomenon is determined in step S3.

  Further, when the acoustic resonance determination unit 151 determines acoustic resonance, the frequency control unit 152 of the control circuit 15 changes the switching frequency of the inverter circuit 16 to the non-acoustic resonance frequency in step S4 as shown in FIG. Control to change.

  In such a configuration, when the AC power supply AC is turned on, the control circuit 15 operates, and the control circuit 15 performs switching control of the switch element Q1 of the boost chopper circuit 14. Thus, the DC power supply circuit 12 starts operating, and the boosted DC voltage VDC is applied to the inverter circuit 16.

  The control circuit 15 also starts switching control of the switch elements Q2 and Q3 of the inverter circuit 16 by the frequency control means 152. At the time of starting the lamp, as shown in FIG. 3, the switching elements Q2 and Q3 are switched and driven at a relatively high frequency and the on-duty is controlled at 50%. When the high-pressure discharge lamp 18 shifts to the lighting state, the frequency control means 152 controls the switching frequency of each switch element Q2, Q3 to be low. For example, if the frequency at the start is approximately half and the frequency at the start is 80 kHz, the frequency is reduced to approximately 40 kHz.

  In this state, the acoustic resonance determination means 151 of the control circuit 15 takes in the lamp voltage detection signal from the lamp voltage detection circuit 20, and determines whether or not the detected lamp voltage is equal to or higher than the reference voltage V1. If the detected lamp voltage does not reach the reference voltage V1, the acoustic resonance determination unit 151 determines the absence of the acoustic resonance phenomenon. At this time, the frequency control means 152 maintains the switching frequency at the time of lighting as it is. If the detected lamp voltage is equal to or higher than the reference voltage V1, the acoustic resonance determination unit 151 determines the occurrence of the acoustic resonance phenomenon. At this time, the frequency control means 152 changes the switching frequency of each switch element Q2, Q3 to a frequency that can avoid the occurrence of the acoustic resonance phenomenon.

  Further, the control circuit 15 varies the output power of the inverter circuit 16 by varying the on-duty of the switch elements Q2 and Q3 by the lamp power adjusting means 153 at the time of lighting. That is, as shown in FIG. 4, the output power of the inverter circuit 16 is highest when the on-duty of each switch element Q2, Q3 is 50% or 50%, and the on-duty of each switch element Q2, Q3 is 40%. , 60% → 30%, 70% → 20%, and 80%, which decrease as the mutual duty difference increases. Therefore, the lamp power adjusting means 153 varies the output power of the inverter circuit 16 by varying the on-duty of each switch element Q2, Q3, and adjusts the lamp power to the rated power of the high-pressure discharge lamp 18.

  In this way, the lamp power can be adjusted by varying the on-duty of each of the switch elements Q2 and Q3 of the inverter circuit 16, so that the output voltage becomes the highest as in the case of controlling the output voltage of the DC power supply. Therefore, it is not necessary to set the withstand voltage of each circuit component in accordance with the above, and the circuit component to be used can be reduced in size and withstand voltage. Thereby, size reduction and cost reduction of an apparatus can be achieved.

  The on-duties of the switch elements Q2 and Q3 are in an inverted relationship with each other. For example, FIG. 5 shows the on / off timing and the current waveform flowing through each switch element Q2 and Q3 when the on-duty of the switch element Q2 is 70% and the on-duty of the switch element Q3 is 30%. FIG. 6 shows the on / off timing and the waveform of current flowing through each of the switch elements Q2 and Q3 when the on-duty of the switch element Q2 is 30% and the on-duty of the switch element Q3 is 70%.

  The lamp power adjusting means 153 drives the switching elements Q2 and Q3 at a high frequency of about 40 kHz. When the on-duty of the switching element Q2 is 70% and the on-duty of the switching element Q3 is 30%, The lamp current flowing in the high pressure discharge lamp 18 is biased.

  For this reason, the lamp power adjusting means 153 switches the on-duty state of the switch elements Q2 and Q3 in FIG. 5 and the on-duty state of the switch elements Q2 and Q3 in FIG. 6 at a long cycle of 100 Hz. That is, the on-duty 70% of the switch element Q2 and the on-duty 30% of the switch element Q3 are continued for 10 msec. When 10 msec elapses, the on-duty 30% of the switching element Q2 and the on-duty 70% of the switching element Q3 are switched at a high frequency of about 40 kHz, and this is continued for 10 msec. When 10 msec elapses, the switching is again made to the on-duty 70% of the switching element Q2 and the on-duty 30% of the switching element Q3.

  By performing such control, a lamp current as shown in FIG. 7 flows in the high-pressure discharge lamp 18, and the unevenness of the lamp current is eliminated. Further, a low frequency power component can be applied to the high pressure discharge lamp 18. As a result, it is possible to light the lamp designed for low frequency without significantly impairing the performance.

  Further, when switching driving is performed with the on-duty of each of the switching elements Q2 and Q3 being 50%, a lamp current as shown in FIG. At this time, the lamp current flowing through the high-pressure discharge lamp 18 is averaged without being biased.

In this embodiment, the on-duty state of each switching element Q2, Q3 is discontinuous from, for example, 70%, 30% to 30%, 70%, or from 30%, 70% to 70%, 30%. However, the present invention is not limited to this. For example, the on-duty state of each switch element Q2, Q3 is changed from 70%, 30% to 30%, 70%, or 30%, 70%. It is also possible to continuously change from 70% to 30%.
By performing such control, the lamp current of the high-pressure discharge lamp 18 changes smoothly as shown in FIG. 9, and the lamp power can be adjusted more accurately. In addition, it can be expected to reduce the noise of winding parts and the like due to a rapid change in lamp power.

(Second Embodiment)
FIG. 10 is a perspective view showing a configuration of a lighting apparatus according to the second embodiment of the present invention. In the figure, reference numeral 100 denotes the high-pressure discharge lamp lighting device according to the first embodiment. The high-pressure discharge lamp lighting device 100 is provided separately from the instrument main body 101. The instrument main body 101 is loaded with a high pressure discharge lamp 18.
In the illuminating device having such a configuration, an illuminating device having the effect of the high-pressure discharge lamp lighting device 100 in the first embodiment can be obtained.

The figure which shows the circuit structure of the high pressure discharge lamp lighting device which concerns on the 1st Embodiment of this invention. The flowchart which shows the determination process of the acoustic resonance phenomenon by the control circuit in the same embodiment, and the variable process of a frequency. The figure which shows the on-off timing and current waveform of each switch element of the inverter circuit at the time of the lamp start in the embodiment. The graph which shows the relationship between the ON duty ratio change of each switch element of the inverter circuit in the same embodiment, and output electric power. The figure which shows the on-off timing and current waveform when the on-duty of each switch element of an inverter circuit is 70% / 30% at the time of the lamp lighting of the embodiment. The figure which shows the on-off timing and current waveform when the on-duty of each switch element of the inverter circuit at the time of lamp lighting in the embodiment is 30% / 70%. The figure which shows the lamp current waveform which flows into a high pressure discharge lamp when the on-duty of each switch element is 70% / 30% and 30% / 70% at the time of the lamp lighting of the embodiment. The figure which shows the lamp current waveform which flows into the high pressure discharge lamp when the on-duty of each switch element is 50% and 50% at the time of the lamp lighting of the embodiment. The figure which shows the lamp current waveform which flows into a high pressure discharge lamp when the on-duty of each switch element changes continuously between 70% / 30% and 30% / 70% at the time of the lamp lighting of the embodiment. The perspective view which shows the illuminating device which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 12 ... DC power supply circuit (DC power supply means), 15 ... Control circuit, 151 ... Acoustic resonance determination means, 152 ... Frequency control means, 153 ... Lamp power adjustment means, 16 ... Inverter circuit (inverter means), 18 ... High pressure discharge lamp DESCRIPTION OF SYMBOLS 19 ... Current detection circuit, 20 ... Lamp voltage detection circuit (lamp voltage detection means), 100 ... High pressure discharge lamp lighting device, 101 ... Instrument main body.

Claims (3)

DC power supply means;
Inverter means for inputting a DC voltage from the DC power supply means and alternately driving on / off switching of at least two switch elements to turn on the high pressure discharge lamp at high frequency;
Lamp voltage detecting means for detecting a lamp voltage of the high pressure discharge lamp;
Acoustic resonance determination means for determining the presence or absence of acoustic resonance using the lamp voltage detected by the lamp voltage detection means;
Frequency control means for controlling the switching frequency of the inverter means to be a non-acoustic resonance frequency based on the determination of the presence or absence of acoustic resonance by the acoustic resonance determination means;
Lamp power adjusting means for adjusting lamp power by changing an on-duty of switching of the switch element in a cycle longer than a switching cycle;
A high pressure discharge lamp lighting device comprising:   2. The high pressure discharge lamp lighting device according to claim 1, wherein the lamp power adjusting means continuously changes the on-duty. A high pressure discharge lamp lighting device according to claim 1 or 2;
A high pressure discharge lamp to be lit by the high pressure discharge lamp lighting device;
An instrument body equipped with the high-pressure discharge lamp;
An illumination device comprising:

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