JP2009217953A - High pressure discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that since L (coil) and C (capacitor) constituting a resonance circuit part have variations in value, the starting discharge voltage which depends on a resonance frequency varies largely by the value of L and C, thereby, they have an element to make lamp lighting unstable. <P>SOLUTION: The discharge lamp lighting device is provided with a high-pressure discharge lamp 16 and a resonance circuit part 22 which supplies AC lamp voltage to start and discharge the high-pressure discharge lamp 16. The starting discharge voltage of the high-pressure discharge lamp 16 is supplied by the resonance voltage obtained by lowering for every fixed time the frequency of the AC lamp voltage from a starting frequency as the start point higher than the resonance frequency of the resonance circuit part 22, further lowering the frequency when the resonance voltage generated in the resonance circuit part 22 increases with the decrease of the frequency from the starting frequency, and reversing the frequency to increase it to the starting frequency when the resonance voltage generated in the resonance circuit part 22 drops or does not change according to the decrease of the frequency. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lighting device used for various high-pressure discharge lamps.

  Hereinafter, a conventional high pressure discharge lamp lighting device will be described with reference to the drawings. FIG. 8 is a block diagram showing a configuration of a conventional high pressure discharge lamp lighting device. In the high pressure discharge lamp lighting device of FIG. 8, a high pressure discharge lamp (lamp) 4 is connected from a DC power source 1 through a DCDC converter 2 and an AC conversion circuit 3. Here, the DCDC converter 2 converts the voltage of the DC power source 1 into a high frequency voltage of several tens of kHz by the PWM control signal 6 from the control circuit 5, and smoothes the high frequency voltage to obtain a converter output voltage.

  The high pressure discharge lamp (lamp) 4 is turned on by applying the voltage waveform generated by the lighting waveform generation circuit 7 to the inverter unit 9 of the AC conversion circuit 3 through the drive circuit 8 together with the converter output voltage. The output inverter voltage is applied to the high-pressure discharge lamp 4 through the resonance circuit unit 10.

  At this time, the lamp voltage applied to the high-pressure discharge lamp 4 is performed by a discharge step in the lamp as in the routine shown in FIG. In the lamp discharge step, first, a voltage of about 3 kV and about 340 kHz is periodically applied as a starting discharge in the first about 1 second. Then, a voltage of about 50 kHz is applied so that a current of about 2 to 3 A flows for about 0.5 seconds as a leveling discharge. Then, after determining whether or not the lamp is lit, a voltage of about 50 kHz is applied so that a current of about 2 to 3 A flows as a preheat discharge for about 1.5 seconds when the lamp is lit. Thereafter, a voltage of 60 to 120 V and 135 kHz in the steady discharge state is continuously applied, and when the lighting is interrupted, the initial start-up discharge is resumed.

  The high voltage required for the starting discharge is obtained by resonating at 340 kHz of the third harmonic when a voltage waveform of 114 kHz and 150 V is applied to the resonance circuit unit 10 from the inverter unit 9 shown in FIG. That is, the starting voltage of about 3 kV and 340 kHz is obtained by the increase of the voltage obtained by this resonance.

For example, Patent Document 1 is known as prior art document information relating to the invention of this application.
JP 2004-127656 A

  In the conventional high pressure discharge lamp lighting device, the relationship between the boosted voltage and frequency in the resonance circuit section 10 of FIG. 8 is as shown by a resonance curve 11a of FIG. Here, the voltage necessary for the starting discharge is Ve, and the resonance frequency is 340 kHz (the frequency of the inverter voltage is 1/3 of this).

  Here, the voltage Ve required for the start-up discharge is resonance by the coil (L) and the capacitor (C) in the resonance circuit section, and the impedance is very small at the resonance point, so a large current flows and consumes a large amount of power. Will do. Therefore, in order to reduce power consumption as much as possible and make it easy to turn on the high pressure discharge lamp, the starting discharge voltage Ve is periodically generated.

  That is, in order to obtain the starting discharge voltage at the point of Ve, the frequency f of the voltage supplied from the inverter unit 9 is made appropriate by a plurality of analog switch adjusting variable resistors provided in the control circuit of FIG. It was set. Thus, a plurality of analog switches are functioned, and the frequency Ve generated from the inverter unit 9 is switched in the order of f1, f2, f3, f2, and f1 shown in FIG.

  However, since L and C configuring the resonance circuit unit 10 in FIG. 8 have variations in values, the resonance curve 11 a shown in FIG. 10 shifts to the left and right depending on the values of L and C. For this reason, for example, when the resonance curve 11a is shifted as indicated by the broken line 11b, Ve decreases to Ve '. In other words, the voltage supplied for the starting discharge greatly varies depending on the values of L and C, and it is necessary to adjust the variable resistance for each set of completed high pressure discharge lamp lighting devices, In addition, there is a problem that there is an element that makes the lamp lighting unstable because the start-up discharge voltage changes greatly with a small adjustment.

  Therefore, the present invention always obtains a stable starting discharge voltage.

  In order to achieve this object, a high pressure discharge lamp and a resonance circuit for supplying an AC lamp voltage for starting discharge of the high pressure discharge lamp are provided, and the starting discharge voltage of the high pressure discharge lamp is a frequency of the AC lamp voltage. When the resonance voltage generated in the resonance circuit rises as the frequency decreases from the starting frequency, the frequency starts from the starting frequency higher than the resonance frequency of the resonance circuit. When the resonance voltage generated in the resonance circuit decreases or does not change as the frequency decreases, the frequency is inverted and supplied by the resonance voltage obtained when increasing to the starting frequency. It is characterized by doing.

  According to the present invention, it is possible to always supply a peak voltage during start-up discharge, and as a result, to provide a high-pressure discharge lamp lighting device that ensures a stable start-up discharge voltage value regardless of variations in the L and C values of the resonance circuit. It is possible.

  Hereinafter, a high pressure discharge lamp lighting device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is a block diagram showing a configuration of a high pressure discharge lamp lighting device according to a first embodiment of the present invention.

  In the high pressure discharge lamp lighting device of FIG. 1, a high pressure discharge lamp (lamp) 16 is connected from a DC power source 13 through a DCDC converter 14 and an AC conversion circuit 15. Here, the DCDC converter 14 converts the voltage of the DC power supply 13 into a high frequency voltage of several tens of kHz by the PWM control signal 18 from the control circuit 17, and smoothes the high frequency voltage to obtain a converter output voltage.

  When the high pressure discharge lamp (lamp) 16 is turned on, the voltage waveform generated by the lighting waveform generation circuit 19 is applied to the inverter unit 21 of the AC conversion circuit 15 through the drive circuit 20 together with the converter output voltage. The output inverter voltage is boosted through the resonance circuit unit 22 and applied to the high-pressure discharge lamp 16.

  At this time, the lamp voltage applied to the high-pressure discharge lamp 16 is performed by a lamp discharge step such as the routine shown in FIG. In the lamp discharge step, first, a voltage of about 3 kV and about 340 kHz is periodically applied as a starting discharge in the first about 1 second. Then, a voltage of about 50 kHz is applied so that a current of about 2 to 3 A flows for about 0.5 seconds as a leveling discharge. Here, after determining whether or not the lamp is lit, a voltage of about 50 kHz is applied so that a current of about 2 to 3 A flows as a preheat discharge for about 1.5 seconds in the lit state. Thereafter, a voltage of 60 to 120 V and 135 kHz in a steady discharge state is applied. In addition, when the lighting is interrupted before the leveling discharge for about 0.5 seconds, or when the lighting does not occur, the start-up discharge is returned to the first one second.

  Here, the high voltage necessary for the starting discharge is supplied from the AC conversion circuit 15 shown in FIG. 1, and the high voltage necessary for the starting discharge can be obtained as follows. First, a voltage waveform of 114 kHz and 150 V is applied from the inverter unit 21 to the resonance circuit unit 22. The resonance circuit unit 22 determines the constants of the inductance and the capacitor so as to resonate at about 340 kHz which is the third harmonic at the frequency of the voltage waveform. And the high voltage required for starting discharge is obtained with the output voltage from the resonance circuit part 22 in the frequency vicinity of the resonance frequency of the resonance circuit part 22.

  That is, the starting voltage of about 3 kV and 340 kHz is obtained by the increase of the voltage obtained by this resonance.

  Here, the relationship between the ramp voltage, which is the boosted voltage in the resonance circuit unit 22 of FIG. 1, and the frequency of the ramp voltage is as shown by a resonance curve 23a shown in FIG. Here, the voltage required for the starting discharge is Ve1, and the resonance frequency is 340 kHz (the frequency of the voltage generated from the inverter shown in FIG. 1 is 114 kHz, which is about 1/3 of the frequency).

  Further, here, the inverter frequency of the inverter voltage waveform generated from the inverter unit 21 in FIG. 1 is controlled by the microcomputer of the control circuit 17, and as shown in FIG. 4, the inverter frequency is lowered from the starting frequency every certain time Δt. ing. As a result, the boosted voltage obtained by the resonance circuit unit 22 shown in FIG. 1 decreases in the inverter frequency in the frequency range A from the frequency fb that is the starting point of the inverter frequency decrease in FIG. 3 to the resonance frequency fr ( As the time elapses), the resonance voltage, which is the lamp starting voltage, increases from Vb to Vr. In B in the frequency region exceeding the resonance frequency fr, the resonance voltage that is the lamp starting voltage decreases as the inverter frequency decreases. When the resonance voltage detecting circuit 24 and the microcomputer shown in FIG. 5 detect that the resonance voltage has decreased, the inverter frequency stops decreasing at the frequency fv at this time, and then the frequency fb from the frequency fv starts. Raise to.

  Alternatively, in a state where the inverter frequency is lowered, the resonance voltage at the last value of the inverter frequency in the frequency region A in FIG. 3 and the resonance voltage at the first value of the inverter frequency in the frequency region B are: When the same value is detected by the resonance voltage detection circuit 24 and the microcomputer shown in FIG. 5, the inverter frequency stops decreasing at the frequency fv at this time, and then increases from that frequency to the starting frequency fb. .

  Here, the inverter frequency that has started to reverse and rise again returns to the frequency region of A, but if the inverter frequency is a value that can obtain Ve1 that is a voltage necessary for lamp starting discharge or more, the frequency fv. When it reaches, it may be fixed for a certain period. In other words, when the frequency at which the decrease in the resonance voltage, which is the lamp starting voltage, is detected as the inverter frequency decreases, is assumed to be fv, the frequency change is temporarily stopped at this frequency fv, and the inverter frequency is inverted and increased after a specified time has elapsed. Then, the frequency may be returned to the starting frequency fb again.

  Further, the frequency at which the decrease in the resonance voltage, which is the lamp starting voltage, is detected as the inverter frequency decreases is defined as fv, and the frequency is inverted and increased from this fv for a time corresponding to a specified period, whereby the frequency range of A It is also possible to approach the frequency fve to obtain Ve1 or more, which is a voltage necessary for the lamp starting discharge, and then stop the frequency change and then raise it to the starting frequency fb.

  With the above configuration and operation, it is possible to obtain the resonance voltage constantly and stably without depending on the constants of L and C of the resonance circuit unit 22 shown in FIG. In other words, even if the resonance frequency changes, the parameter for obtaining the optimum resonance voltage is the change of the resonance voltage with respect to the increase of the inverter frequency. Even in this case, it can be obtained without problems.

  In other words, even when the resonance curve is shifted due to fluctuations in the constants of L and C as in the curves 23a and 23b shown in FIG. 3, the time required to reach from fb to fv and fve only changes. Yes, Ve1 does not change the voltage required for the starting discharge obtained there. Of course, although it is necessary to determine the constants of L and C so as to have the maximum value Vr of the resonance voltage for obtaining Ve1 which is a voltage necessary for the lamp starting discharge, this Vr is a general value of L and C. A large variation range of 5 to 10% does not cause a large change.

  The above-described supply of the resonance voltage for the lamp starting discharge can be shown as shown in FIGS. 6A to 6D as the relationship between the time and the resonance voltage.

  First, as shown in FIG. 6A or FIG. 6B, the relationship between time and the resonance voltage is taken as an example in which the peak waveform has two peaks as the time changes. As described above, this is because the inverter frequency shown in FIG. 3 falls from the high frequency side to the low frequency side of the starting frequency fb and exceeds the resonance frequency fr, and overruns from the high frequency A region to the low frequency B region. This is due to returning from the shot state to the A region again.

  The resonance voltage shown in FIG. 6A is increased from the inverter frequency fv shown in FIG. 3 by inverting the frequency only for a time corresponding to a specified period, and then fixing the frequency for an arbitrary period. This is when the frequency rises. Further, the resonance voltage shown in FIG. 6B is obtained when the inverter frequency fv shown in FIG. 3 is changed from the inverter frequency inverted at fv to the starting frequency fb again after the frequency change is continued. . Specifically, the time for changing the inverter frequency is set by a change step (for example, Δt = 0.2 (μsec)) as shown in FIG. 4, and the resonance voltage waveform having the above-described peak is a voltage necessary for the starting discharge. By making Ve1 continue for about 1 (msec) or more, the high-pressure discharge lamp (lamp) 16 shown in FIG. 1 can be reliably turned on.

  Further, as the lamp starting voltage follows a change from the starting point to the peak to the starting point, as described above, the power peak can be controlled in a short time of about 1 (msec). Can be suppressed. In addition to this, lighting can be facilitated by instantaneously setting the peak voltage to two points.

  Similarly to the above, the resonance voltage shown in FIG. 6 (c) returns the inverter frequency inverted at fv from the frequency fv to the starting frequency fb again after fixing the frequency at the inverter frequency fv shown in FIG. Is the case. Thereby, after maintaining the voltage Ve1 required for the start-up discharge, it is possible to surely control the period ΔT during which the power is peaked, thereby suppressing power consumption more than necessary. In addition to this, lighting can be facilitated by instantaneously setting the peak voltage to two points.

  In addition, as shown in FIG. 6D, it is possible to perform reliable lighting by having three or more peak voltages. In this case, the inverter frequency can have three peak voltages by changing and controlling in the order of fb → fv → variation stop → fr → fv → variation stop → fb shown in FIG.

  In the high-pressure discharge lamp 16 shown in FIG. 1, the higher the peak voltage waveform to be applied, the more likely the start-up, that is, the lighting, occurs, but the longer the time during which the resonance voltage becomes higher than the voltage Ve1 required for the start-up discharge. However, the power consumption in the discharge lighting device becomes larger than necessary. Therefore, in order to suppress this power consumption, by providing a flat portion between the peak voltage waveform as shown in FIGS. 6C and 6D, the high-pressure discharge lamp of FIG. The (lamp) 16 can be turned on and the power consumption can be reduced.

  Here, Δt in FIG. 4 is a fixed time, but may be changed according to the resonance voltage around Δt. For example, when the inverter frequency approaches the resonance frequency and the increase of the resonance voltage per Δt becomes small, the time of Δt may be shortened accordingly.

  Next, the resonance voltage detection circuit of the resonance circuit unit 22 shown in FIG. 1 will be described. The resonance voltage detection circuit 24 shown in FIG. 5 uses the cross-point voltage of Ca and Cb as a resistance in L and C constituting the resonance circuit unit 22 (C is a series configuration of Ca and Cb to halve the application of a high voltage). The voltage is divided by 25 and the resistor 26. Further, an AC resonant voltage is rectified by the diode 27 and the capacitor 29, and the rectified voltage (vp) is generated through the resistor 30 and the Zener diode 31 to generate a resonance detection voltage (vz). Read by D converter (not shown). Here, the voltage read by the A / D converter (not shown) of the microcomputer (not shown) is also used for detection when the high pressure discharge lamp (lamp) 16 is lit.

  That is, when the resonance detection voltage (vz) = Vb at the frequency fb which is the starting point of the inverter frequency shown in FIG. 7 is turned on, when the high pressure discharge lamp (lamp) 16 in FIG. Therefore, the resonance detection voltage (vz) is close to Vs (approximately 0 V) shown in FIG. If the difference (ΔV) between Vb and Vs is detected, the lighting state of the lamp can be detected. However, there is a large voltage difference between about 5 (V) of the lamp lighting detection voltage and about 3 (kV) of the resonance voltage peak, which is inconvenient for the comparison operation. Therefore, by utilizing the characteristics in the vicinity of a constant voltage in a non-linear element such as the Zener diode 31 shown in FIG. 5, the peak of the resonance voltage is compressed in cooperation with the resistor 30, that is, the vp waveform is compressed into the vz waveform, By detecting the fluctuation of the vz waveform, the lighting of the lamp and the peak of the resonance voltage are detected.

  Further, the vicinity of the peak of the resonance voltage is a high voltage of several (kV), and a large noise is generated at each frequency step. Therefore, during the time change step (Δt = 0.2 μsec) for changing the frequency, The resonance detection voltage (vz) read by the A / D converter is averaged by the microcomputer to stably detect the peak.

  As a result, a stable peak voltage can be obtained while suppressing noise, and power consumption can be suppressed and fluctuations can be reduced, and at the same time, lighting of the lamp can be ensured.

  The high pressure discharge lamp lighting device of the present invention has an effect of stabilizing the discharge voltage during start-up discharge of the high pressure discharge lamp, and is useful in various electronic devices.

1 is a circuit block diagram of a high pressure discharge lamp lighting device according to an embodiment of the present invention. Start-up discharge routine diagram of a high-pressure discharge lamp lighting device according to an embodiment of the present invention The relationship figure of the lamp voltage and lamp voltage frequency of the high pressure discharge lamp lighting device in one embodiment of the present invention The relationship figure of the lamp voltage frequency and time of the high pressure discharge lamp lighting device in one embodiment of the present invention 1 is a circuit diagram of a high pressure discharge lamp lighting device according to an embodiment of the present invention. (A) First relationship diagram of lamp voltage and time of high-pressure discharge lamp lighting device in one embodiment of the present invention, (b) Second relationship diagram, (c) Third relationship diagram, d) Fourth relationship diagram FIG. 3 is a relationship diagram of lamp voltage and time when the high-pressure discharge lamp lighting device according to an embodiment of the present invention is turned on. Circuit block diagram of conventional high pressure discharge lamp lighting device Start-up discharge routine diagram of a conventional high pressure discharge lamp lighting device Relationship diagram between lamp voltage and lamp voltage frequency of a conventional high pressure discharge lamp lighting device

Explanation of symbols

13 DC power supply 14 DCDC converter 15 AC conversion circuit 16 High-pressure discharge lamp (lamp)
17 control circuit 18 PWM control signal 19 lighting waveform generation circuit 20 drive circuit 21 inverter unit 22 resonance circuit unit

Claims (6)

A high pressure discharge lamp,
A resonance circuit for supplying an AC lamp voltage for starting and discharging the high-pressure discharge lamp,
The starting discharge voltage of the high pressure discharge lamp is:
Decreasing the frequency of the AC lamp voltage at regular intervals starting from a starting frequency higher than the resonant frequency of the resonant circuit,
When the resonance voltage generated in the resonance circuit rises as the frequency drops from the starting frequency, the frequency is further lowered,
When the resonance voltage generated in the resonance circuit decreases or does not change as the frequency decreases, the frequency is inverted,
A high pressure discharge lamp lighting device supplied by a resonance voltage obtained when the frequency is raised to the starting frequency. When the resonant voltage generated in the resonant circuit decreases or does not change as the frequency decreases,
The high-pressure discharge lamp lighting device according to claim 1, wherein the frequency is inverted and raised after holding the frequency at that time. The high-pressure discharge lamp lighting device according to claim 1 or 2, wherein the resonance voltage with the passage of time has a peak portion composed of two or more vertices. Resonance voltage with the passage of time is a peak part composed of two or more vertices,
The high pressure discharge lamp lighting device according to claim 1 or 2, comprising a flat portion between the two apexes. By detecting a decrease in the resonance voltage of the resonance circuit with the resonance voltage detection circuit,
The high pressure discharge lamp lighting device according to any one of claims 1 to 4, which detects lighting of the high pressure discharge lamp. Using non-linear elements,
A second resonance voltage is obtained by compressing the resonance voltage of the resonance circuit,
The high pressure discharge lamp lighting device according to claim 5, wherein the peak of the resonance voltage is detected from the peak of the second resonance voltage.

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