JP4702038B2 - High intensity discharge lamp lighting device and projector - Google Patents

Description

  The present invention relates to a high-intensity discharge lamp lighting device and a projector for starting and lighting a high-intensity discharge lamp such as a metal halide lamp.

  High-intensity discharge lamps such as metal halide lamps and ultra-high pressure mercury lamps have good luminous efficiency and can be miniaturized, so in addition to general lighting equipment, in-vehicle lamps such as headlamps It is increasingly used as a light source for projector television receivers.

  Since a high voltage is required to start this type of discharge lamp, an igniter circuit that generates a high-voltage pulse starting voltage is generally provided in a high-intensity discharge lamp lighting device.

  This high-intensity discharge lamp lighting device includes, for example, a polarity inversion circuit that converts a DC voltage into a rectangular wave AC voltage, a resonance circuit (for example, an LC series resonance circuit) to which a rectangular wave AC voltage is applied, and a capacitor in parallel. Using the connected high-intensity discharge lamp and the resonance voltage of the resonance circuit, a pulse starting voltage having a peak value of several kV and a width of several tens to several thousand nsec is generated and applied to the high-intensity discharge lamp. It consists of an igniter circuit.

  This igniter circuit includes, for example, a pulse transformer that boosts a primary voltage to a secondary voltage as a pulse starting voltage and applies it to a high-intensity discharge lamp, a capacitor for generating the primary voltage, and a resonance voltage applied to the capacitor. And a switch element that applies the primary voltage to the pulse transformer (its primary winding) when the primary voltage generated by the capacitor reaches the trigger voltage. As the switch element, for example, a bidirectional two-terminal element such as a discharge gap or a triac having a predetermined on-voltage (breakdown threshold level) is used as the trigger voltage. A high-intensity discharge lamp is started by generating glow discharge by applying the above pulse starting voltage, and AC power is supplied from the polarity inversion circuit while glow discharge is being generated. Transition to lighting (leads to a steady lighting state).

  In such a high-intensity discharge lamp lighting device, a primary voltage and a no-load voltage sufficient to start the high-intensity discharge lamp are obtained by resonating the resonance circuit, so that driving corresponding to the resonance frequency of the resonance circuit is performed. Each switch element of the polarity inversion circuit must be turned on and off at a frequency. For this reason, first, the resonance condition (value of each element) of the resonance circuit is set so as to obtain the primary voltage and the no-load voltage, and then the drive frequency is for operating the resonance circuit under the resonance condition. The frequency will be set.

In Patent Document 1, the frequency of the output voltage of the inverter circuit is gradually increased, and the frequency of the output voltage of the inverter circuit when the amplitude of the oscillating voltage of the resonant circuit becomes equal to or greater than a predetermined value. A lamp lighting device for setting the frequency is described. In one embodiment, if the oscillation voltage of the resonance circuit becomes equal to or higher than a predetermined value, it is determined that the resonance point has been entered, and the frequency of the output voltage of the inverter circuit is fixed at the frequency at that time, or more than the detected frequency. Fix to a slightly higher frequency. In another embodiment, the frequency of the output voltage of the inverter circuit is set to a frequency lower than 1 / N times the resonant frequency of the resonant circuit, and then the frequency is gradually increased so that the switch element of the igniter circuit breaks. The frequency of the output voltage of the inverter circuit is fixed to the frequency when it goes down. In this case, because of the variation of about ± 15% of the discharge voltage of the switch element, the frequency of the output voltage of the inverter circuit is fixed to a frequency several percent higher than the frequency at the time of breakdown.
JP 2004-127656 A (Claim 1, paragraphs 0038, 0074, 0075)

  However, in the configuration in which the drive frequency is set based on the resonance condition, it is necessary to suppress the tolerance of the value of each element in the resonance circuit, so a component with extremely small variation must be used for the resonance circuit. It was a factor of cost increase.

  For this reason, if the drive frequency is adjusted and set so as to satisfy the resonance condition at the time of manufacture or shipment, it is possible to eliminate the necessity of extremely reducing the tolerance of the value of each element in the resonance circuit. However, such manual adjustment has a problem that man-hours and costs increase.

  In addition, since the invention described in Patent Document 1 is controlled by a phase advance current, there is a problem that a large stress is applied to the switch element.

  The present invention has been made in view of the above circumstances, eliminates the need for manual circuit adjustment, eliminates the need to extremely reduce the tolerance of the value of each element in a resonant circuit, and eliminates the need for circuit switch elements. An object of the present invention is to provide a high-intensity discharge lamp lighting device and a projector that can reduce stress.

  The high-intensity discharge lamp lighting device according to the first aspect of the present invention for solving the above-described problem is a DC conversion circuit for obtaining a variable DC voltage from an input voltage of a power source, and inverting the polarity of the DC voltage at a variable frequency. A polarity inverting circuit for obtaining an AC voltage, a resonance circuit to which the AC voltage is applied, a resonance voltage corresponding to the frequency of the AC voltage is generated and applied to the high-intensity discharge lamp, and the resonance voltage is applied. When a level corresponding to a trigger voltage is reached, an igniter circuit that generates a pulse start voltage and applies the pulse start voltage to the high-intensity discharge lamp, a resonance voltage detection circuit that detects the resonance voltage, and the resonance voltage includes the trigger voltage A second voltage level higher than a level corresponding to an upper limit value of the trigger voltage variation range from a first voltage level lower than a level corresponding to a lower limit value of the voltage variation range. A frequency control circuit for adjusting the variable frequency so as to increase stepwise or continuously, the frequency control circuit stepwise or from the first voltage level to the second voltage level. Based on a value obtained from the resonance voltage detected by the resonance voltage detection circuit by decreasing the variable frequency stepwise or continuously from the first frequency to a second frequency lower than the first frequency so as to continuously increase. Determining whether or not the resonance voltage has reached the second voltage level, and after obtaining a determination result indicating that the resonance voltage has reached the second voltage level, the resonance voltage is set to the second voltage level. The variable frequency is fixed so as to be maintained at two voltage levels.

  With this configuration, the trigger voltage variation range can be designed to fall between the first voltage level and the second voltage level without making the tolerance of the value of each element in the resonance circuit very small. This eliminates the need for manual circuit adjustment and eliminates the need for very small tolerances for the values of the elements in the resonant circuit. In addition, since the control is performed with the slow phase current, it is possible to reduce the stress on the switch element of the circuit.

  According to a second aspect of the present invention, in the high-intensity discharge lamp lighting device, the frequency control circuit includes the variable frequency so that the resonance voltage increases stepwise from the first voltage level to the second voltage level. Stepwise from a first frequency to a lower second frequency, wherein the first frequency and the second frequency are higher than a resonance frequency of the resonance circuit, and the second frequency is near the resonance frequency. It is characterized by being set. In this configuration, the resonance voltage can be increased stepwise from the first voltage level to the second voltage level, and the second voltage level corresponds to the upper limit value of the variation range of the trigger voltage for reliably moving the igniter circuit. Can be higher than level.

  According to a third aspect of the present invention, in the high-intensity discharge lamp lighting device, the first frequency and the second frequency are higher than an odd number of the resonance frequency, and the second frequency is equal to the resonance frequency. It is set in the vicinity of an odd number. In this configuration, the resonance voltage can be increased stepwise from the first voltage level to the second voltage level by the harmonic component of the AC voltage obtained by the polarity inverting circuit, and the igniter circuit can be reliably connected to the second voltage level. The level can be higher than the level corresponding to the upper limit value of the variation range of the trigger voltage for movement.

  According to a fourth aspect of the present invention, in the high-intensity discharge lamp lighting device, the resonance voltage detection circuit applies a voltage whose level changes every time the igniter circuit generates the pulse starting voltage when applied to the igniter circuit. And detecting the generation interval time of the pulse starting voltage based on the detected voltage, and the frequency control circuit determines that the resonance voltage is the second based on the value of the generation interval time of the pulse starting voltage. After determining whether or not a voltage level has been reached and obtaining a determination result indicating that the resonance voltage has reached the second voltage level, the resonance voltage is maintained at the second voltage level. The variable frequency is fixed. This configuration also eliminates the need for manual circuit adjustment, eliminates the need for extremely small tolerances for the values of the elements in the resonant circuit, and reduces stress on the switch elements of the circuit.

  According to a fifth aspect of the invention, the projector includes the high-intensity discharge lamp lighting device and the high-intensity discharge lamp.

  According to the present invention, manual circuit adjustment is not required, the necessity of extremely reducing the tolerance of the value of each element in the resonance circuit can be eliminated, and the stress on the switch element of the circuit can be reduced.

  FIG. 1 shows a high-intensity discharge lamp lighting device according to a first embodiment of the present invention. As shown in FIG. 2, the high-intensity discharge lamp lighting device 10 according to the first embodiment includes, for example, a projector together with a discharge lamp 2, an optical system 3, an external signal input unit 4, a plurality of cooling fans 5, a power supply unit 6, and the like. 1 is mounted. The discharge lamp 2 is, for example, a high-intensity discharge lamp such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a sodium lamp, or a metal halide lamp. The power source unit 6 is configured to supply various power sources from a commercial power source to each unit of the projector 1, and includes a DC power source 7 for the high-intensity discharge lamp lighting device 10.

  As shown in FIG. 1, the high-intensity discharge lamp lighting device 10 is configured to start and light the discharge lamp 2, and includes, for example, a DC-DC conversion circuit (DC conversion circuit) 11, a polarity inversion circuit 12, and a resonance circuit. 13 includes an igniter circuit 14, a resonance voltage detection circuit 15, and a frequency control circuit 16.

  The DC-DC conversion circuit 11 is configured to obtain a variable DC voltage V11 from the input voltage Vin of the DC power supply 7. For example, the DC-DC conversion circuit 11 includes a diode D11 connected in reverse parallel to the DC power supply 7, and a switch element (eg, FET) Q11 inserted between the cathode and one end (positive terminal) of the DC power supply 7. A capacitor C11 connected in parallel with the diode D11, an inductor (choke coil) L11 inserted between this end and the cathode of the diode D11, a detection circuit 111, a lamp power control circuit 112, and a drive circuit 113. The detection circuit 111 detects the voltage of the capacitor C11 that is the output voltage of the DC-DC conversion circuit 11 and the current flowing through the inductor L11. Based on the detected voltage and current, the lamp power control circuit 112 generates a control signal for setting the voltage of the capacitor C11 to a voltage for starting or lighting the discharge lamp 2. In accordance with this control signal, the drive circuit 113 adjusts the duty and frequency of the drive signal of several tens kHz to the switch element Q11. Thereby, the switch element Q11 is turned on and off at a high frequency according to the adjusted drive signal, and the voltage of the capacitor C11 is transformed (stepped up or stepped down) according to the state of the load (discharge lamp 2).

  The polarity inversion circuit 12 is configured to invert the polarity of the DC voltage V11 at a variable frequency to obtain a rectangular wave AC voltage. For example, the polarity inversion circuit 12 includes a bridge circuit and drive circuits 121 and 122. The bridge circuit is configured by connecting switch elements Q1 and Q2 connected in series and switch elements Q3 and Q4 connected in series to the output (capacitor C11) of the DC-DC conversion circuit 11 in parallel. . For each switch element of the bridge circuit, an FET can be used, and for example, a bipolar transistor and a diode connected in reverse parallel thereto can be used. The drive circuits 121 and 122 turn on and off the switch elements Q1 and Q4 and the switch elements Q2 and Q3 alternately at a variable frequency according to the control of the frequency control circuit 16. As a result, a rectangular wave AC voltage is generated between the connection point of the switch elements Q1 and Q2 and the connection point of the switch elements Q3 and Q4 (hereinafter referred to as “output of the polarity inverting circuit 12”).

  The resonance circuit 13 is configured to be applied with a rectangular wave AC voltage, generate a resonance voltage corresponding to the frequency of the AC voltage (the frequency of the fundamental wave in the first embodiment), and apply it to the discharge lamp 2. . For example, the resonance circuit 13 includes an inductor L13 and a capacitor C13 connected in series, and is connected to the output of the polarity inverting circuit 12. The discharge lamp 2 and a part of the igniter circuit 14 (secondary winding of the pulse transformer) are connected in parallel to the capacitor C13 through a socket.

  The igniter circuit 14 is configured to generate a pulse starting voltage and apply it to the discharge lamp 2 when a resonant voltage is applied and reaches a level corresponding to the trigger voltage. For example, the igniter circuit 14 includes a resistor R14, a diode D14 to which an anode (a connection point of L13 and C13) and an anode are connected via a resistor R14, and a cathode and the other end of the capacitor C13. A capacitor C14, a switch element Q14, and a pulse transformer PT14 connected between the capacitors are provided. The switch element Q14 is a discharge gap, a triac, a thyristor or the like, and has an on-voltage (breakdown threshold level) within a predetermined variation range as a trigger voltage. The pulse transformer PT14 has a primary winding and a pair of secondary windings, and the primary winding is connected in series with the switch element Q14, while the primary winding and the switch element Q14 in the series set. Is connected in parallel with the capacitor C14. The pair of secondary windings are respectively connected in series with both ends of the discharge lamp 2, while the secondary winding, the discharge lamp 2 and the secondary winding of the series set are connected in parallel with the capacitor C13. . In this configuration, the resonant voltage generated across the capacitor C13 is rectified by the diode D14 and applied to the capacitor C14. When the voltage of the capacitor C14 reaches the trigger voltage, the switch element Q14 is turned on. As a result, the pulse transformer PT14 receives the discharge voltage from the capacitor C14, generates a pulse starting voltage having a peak value of several kV and a width of several tens to several thousand nsec according to the turns ratio, and applies it to the discharge lamp 2.

  The resonance voltage detection circuit 15 is configured to detect a resonance voltage. For example, the resonance voltage detection circuit 15 includes a diode D15 to which the anode and the connection point of the inductor L13 and the capacitor C13 are connected, a resistor R151 to which the cathode and one end are connected, and the other end to the DC-DC conversion circuit 11. The resistor R152 and the capacitor C15 are connected in parallel with the negative terminal of the output. In this configuration, the resonance voltage at the connection point of the inductor L13 and the capacitor C13 is rectified, divided and smoothed to obtain the detection voltage V15.

  The frequency control circuit 16 has a start control mode and a lighting control mode, and is configured by, for example, a microcomputer and a program so as to control the switching frequency of each switch element of the polarity inversion circuit 16. The frequency control circuit 16 controls the switching timing so that each pair of diagonal switch elements is not turned on at the same time.

  In the start control mode, the frequency control circuit 16 corresponds to the upper limit value of the trigger voltage variation range from the first voltage level whose resonance voltage is lower than the level corresponding to the lower limit value of the trigger voltage variation range of the switch element Q14. The variable frequency for inverting the polarity of the DC voltage V11 is adjusted so as to increase stepwise or continuously (stepwise in the first embodiment) to a second voltage level higher than the level to be applied. The

  Specifically, as shown in FIG. 3, the frequency control circuit 16 increases the resonance voltage stepwise from the level of the voltage Vs as the first voltage level to the level of the voltage Ve as the second voltage level. In addition, the variable frequency is lowered stepwise from the frequency fs to the lower frequency fe. The frequencies fs and fe are set to frequencies in the range of several tens of kHz to several hundreds of kHz higher than the resonance frequency f0 of the resonance circuit 13, and the frequency fe is set in the vicinity of the resonance frequency f0.

  Further, the frequency control circuit 16 determines whether or not the resonance voltage has reached the level of the voltage Ve based on the value obtained from the resonance voltage detected by the resonance voltage detection circuit 15 (A / D conversion value of V15). After the determination and the determination result that the resonance voltage has reached the level of the voltage Ve is obtained, the variable frequency is fixed so as to maintain the resonance voltage at the level of the voltage Ve.

  Furthermore, the frequency control circuit 16 stops the start-up and lighting processes when the determination result is obtained a specified number of times. This specified number of times is for preventing the discharge lamp 2 from entering the infinite loop without being lit due to a failure.

  Next, the transition to the lighting control mode will be described. The frequency control circuit 16 determines whether or not the discharge lamp 2 is started and lit based on the digital value of the detection voltage V15. When the discharge lamp 2 is lit, the frequency control circuit 16 shifts to the lighting control mode. When the discharge lamp 2 starts and lights up, the load state of the polarity inverting circuit 12 changes from the high impedance state to the low impedance state, and the voltage of the capacitor C13 changes (decreases). It can be determined whether or not the discharge lamp 2 has been lit by determining whether or not the threshold level has been exceeded.

  When the mode is switched to the lighting control mode, the frequency control circuit 16 supplies power to the discharge lamp 2 by turning on and off each switch element of the polarity inversion circuit 12 at a high frequency for a predetermined time (several seconds). The frequency is changed to a low frequency within a range of several tens Hz to several hundreds Hz, and the duty and switching frequency of the switch element Q11 of the DC-DC conversion circuit 11 are controlled, so that the amount of power supplied to the discharge lamp 2 is changed to the discharge lamp. 2 is adjusted to the amount of power for steady lighting.

  Next, the operation of the first embodiment will be described with reference to FIGS. When the power is turned on and the high-intensity discharge lamp lighting device 10 is started (S11), the start control mode is entered, and the frequency control circuit 16 initializes each part of the high-intensity discharge lamp lighting device 10 (the number of loops). (Including initialization to zero) (S12), and a variable frequency f for inverting the polarity of the DC voltage V11 is set to a command value (in this case, the frequency fs) (S13). As a result, each switch element of the polarity inverting circuit 12 is turned on and off at the frequency fs, and a starting voltage Vs is generated in the capacitor C13 of the resonance circuit 13 and applied to the discharge lamp 2 and the igniter circuit 14.

  Subsequently, the frequency control circuit 16 determines whether or not the discharge lamp 2 is started and lit based on the detected voltage V15 (S14). If the discharge lamp 2 is lit (YES in S14), the lighting control is performed. The mode is switched to the above-described lighting control (S15). On the other hand, if the discharge lamp 2 is not lit (NO in S14), the frequency control circuit 16 determines whether or not the number of loops is a specified number (S16), and if the number of loops is a specified number (in S16). YES), the start-up and lighting processes are stopped (END).

  If the number of loops is not the specified number (NO in S16), the frequency control circuit 16 detects the resonance voltage with the resonance voltage detection circuit 15 (S17), and the detection value (V15) obtained from this resonance voltage is the specified value ( It is determined whether or not the voltage Ve) has been reached (S18). If the detected value does not reach the specified value (NO in S18), the frequency control circuit 16 subtracts a predetermined frequency Δf from the current variable frequency f to obtain a command value (S19), and the process goes to step S13. return. Accordingly, since the variable frequency f is set to f−Δf, each operation waveform of the high-intensity discharge lamp lighting device changes every time step S19 is entered as shown in FIG. For example, the igniter circuit 14 applies a pulse starting voltage to the discharge lamp 2 when the detection voltage V15 and the voltage of the capacitor C14 rise and the voltage of the capacitor C14 reaches the trigger voltage Vbd. As a result, when the discharge lamp 2 is turned on, the process branches to step S15 in step S14. Although the drive signals for Q2 and Q3 are not shown in FIG. 5, their waveforms are opposite to those for Q1 and Q4.

  If the detected value reaches the specified value (YES in S18), the frequency control circuit 16 increments the number of loops by 1, and fixes the command value (variable frequency f) to the current frequency (fe) (S20). The process returns to step S13. Thereby, the igniter circuit 14 to which the voltage Ve corresponding to the frequency fe is applied generates the pulse starting voltage surely and quickly until the discharge lamp 2 starts and lights up or the number of loops reaches the prescribed number of S16. Therefore, the discharge lamp 1 can be started reliably and quickly.

  In one variant embodiment, the variable frequencies f corresponding to the levels of the voltages Vs and Ve are frequencies fs and fe higher than f0 / n, respectively, as shown in FIGS. 6 and 7, where n is It is an odd number (3 in the example of FIG. 7). The frequency fe is set in the vicinity of f0 / n. The resonance uses an n-order harmonic of a variable frequency f, and the resonance frequency is decremented by a predetermined frequency from n times the frequency fs to n times the frequency fe. Even in this configuration, since the resonance voltage rises from the level of the voltage Vs to the level of the voltage Ve, the resonance circuit and the igniter circuit operate in the same manner as those in the first embodiment. In particular, when the duty of polarity inversion is about 50%, it is effective to use strong resonance with harmonics at odd numbers. Thus, by using the higher harmonics and increasing the resonance frequency f0 of the resonance circuit 13, the constants of the inductor L13 and the capacitor C13 of the resonance circuit 13 can be further reduced, and the high-intensity discharge lamp lighting device 10 can be reduced in size. For example, in the case of the third harmonic, L13 × C13 is 1/9 from the following equation, and the size can be reduced.

f0 = 1 / (2π × √ (L13 × C13))
f0 ′ = 3 × f0
(L13 × C13) ′ = (L13 × C13) / 9
FIG. 8 shows a high-intensity discharge lamp lighting device according to a second embodiment of the present invention. As shown in FIG. 8, the high-intensity discharge lamp lighting device 20 according to the second embodiment includes a DC-DC conversion circuit 11, a polarity inversion circuit 12, a resonance circuit 13, and an igniter circuit 14 in the same manner as in the modified embodiment. As a feature of the second embodiment, a resonance voltage detection circuit 25 and a frequency control circuit 26 are provided.

  The resonance voltage detection circuit 25 detects a voltage that is applied to the igniter circuit 14 and changes in level each time the igniter circuit 14 generates a pulse starting voltage, and based on the detected voltage, the generation interval time of the pulse starting voltage is detected. Configured to measure. For example, the resonance voltage detection circuit 25 includes a voltage detection unit such as a differential amplifier circuit (not shown) and a timer for measuring time, and detects the voltage of the capacitor C14 of the igniter circuit 14 to generate a pulse starting voltage generation time. Measure the interval. The timer is reset when the pulse starting voltage is generated.

  The frequency control circuit 26 determines whether or not the resonance voltage has reached the level of the voltage Ve based on the generation interval time of the pulse starting voltage, and the determination result that the resonance voltage has reached the level of the voltage Ve is obtained. After being obtained, the variable frequency f is fixed so as to maintain the resonance voltage at the level of the voltage Ve. More specifically, the frequency control circuit 26 determines whether or not the generation interval time is equal to or less than a predetermined specified time (tr). If the generation interval time is equal to or less than the predetermined time, the frequency control circuit 26 f is fixed to the frequency fe. Except this, it is the same as the above-mentioned embodiment.

  Next, the operation of the second embodiment will be described with reference to FIGS. Steps S11 to S16 are the same as in the first embodiment. If the number of loops is not the specified number (NO in S16), the frequency control circuit 26 measures the generation time (measured value) of the pulse starting voltage with the resonance voltage detection circuit 25 (S27), and the measured value is the specified value ( It is determined whether or not the predetermined time tr) is reached (S28). If the measured value does not fall below the specified value (NO in S28), the frequency control circuit 26 subtracts a predetermined frequency Δf from the current variable frequency f to obtain a command value (S19), and the process is step S13. Return to. As shown in FIG. 10, every time step S19 is entered, the voltage of the capacitor C13 increases stepwise and the measured value decreases stepwise (see t0, t1, t2 in FIG. 10).

  If the measured value is less than or equal to the specified value (YES in S28), the frequency control circuit 26 increments the number of loops by 1, and fixes the command value (variable frequency f) to the current frequency (fe) (S20). The process returns to step S13.

1 is a circuit diagram of a high-intensity discharge lamp lighting device according to a first embodiment of the present invention. It is a schematic block diagram of the projector of FIG. It is explanatory drawing of the resonance operation | movement of the high-intensity discharge lamp lighting device of FIG. It is an operation | movement flowchart of the high-intensity discharge lamp lighting device of FIG. It is an operation | movement waveform diagram of the high-intensity discharge lamp lighting device of FIG. It is explanatory drawing of the resonance operation | movement of one deformation | transformation embodiment. It is an operation | movement waveform diagram of the deformation | transformation embodiment. It is a circuit diagram of the high-intensity discharge lamp lighting device of 2nd Embodiment by this invention. It is an operation | movement flowchart of the high-intensity discharge lamp lighting device of FIG. It is an operation | movement waveform diagram of the high-intensity discharge lamp lighting device of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Projector 2 Discharge lamp 7 DC power supply 10,20 High-intensity discharge lamp lighting device 11 DC-DC conversion circuit 12 Polarity inversion circuit 13 Resonance circuit 14 Igniter circuit 15, 25 Resonance voltage detection circuit 16, 26 Frequency control circuit

Claims (5)

A DC conversion circuit that obtains a variable DC voltage from the input voltage of the power supply;
A polarity inverting circuit for inverting the polarity of the DC voltage at a variable frequency to obtain an AC voltage;
A resonance circuit that is applied with the AC voltage, generates a resonance voltage corresponding to the frequency of the AC voltage, and applies the resonance voltage to the high-intensity discharge lamp;
An igniter circuit that generates a pulse starting voltage and applies it to the high-intensity discharge lamp when the resonant voltage is applied and reaches a level corresponding to a trigger voltage;
A resonance voltage detection circuit for detecting the resonance voltage;
The resonant voltage is stepped from a first voltage level lower than a level corresponding to the lower limit value of the trigger voltage variation range to a second voltage level higher than a level corresponding to the upper limit value of the trigger voltage variation range. A frequency control circuit for adjusting the variable frequency so as to continuously increase, and
The frequency control circuit includes:
The variable frequency is stepped or continuously from the first frequency to a lower second frequency so that the resonant voltage increases stepwise or continuously from the first voltage level to the second voltage level. To
Based on a value obtained from the resonance voltage detected by the resonance voltage detection circuit, it is determined whether or not the resonance voltage has reached the second voltage level,
After the determination result that the resonance voltage has reached the second voltage level is obtained, the variable frequency is fixed so as to maintain the resonance voltage at the second voltage level. Brightness discharge lamp lighting device. The frequency control circuit reduces the variable frequency stepwise from the first frequency to a lower second frequency so that the resonance voltage stepwise increases from the first voltage level to the second voltage level. ,
The first frequency and the second frequency are higher than a resonance frequency of the resonance circuit,
The high-intensity discharge lamp lighting device according to claim 1, wherein the second frequency is set in the vicinity of the resonance frequency. The first frequency and the second frequency are higher than an odd number of the resonance frequency;
The high-intensity discharge lamp lighting device according to claim 1, wherein the second frequency is set in the vicinity of an odd number of the resonance frequency. The resonant voltage detection circuit detects a voltage that is applied to the igniter circuit and changes in level each time the igniter circuit generates the pulse starting voltage, and generates the pulse starting voltage based on the detected voltage. Measure the interval time,
The frequency control circuit determines whether the resonance voltage has reached the second voltage level based on a value of the generation interval time of the pulse starting voltage, and the resonance voltage has reached the second voltage level. 2. The high-intensity discharge lamp lighting device according to claim 1, wherein the variable frequency is fixed so that the resonance voltage is maintained at the second voltage level after the determination result indicating that the determination has been made. A high-intensity discharge lamp lighting device according to any one of claims 1 to 4,
A projector comprising: the high-intensity discharge lamp.

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