JP2004288375A - High pressure discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high pressure discharge lamp lighting device performing sure operation in a low price. <P>SOLUTION: The high pressure discharge lamp lighting device is composed of a DC power source circuit converting an AC power into DC power; an inverter circuit converting the output of the DC power source circuit into a high frequency; a driver circuit driving the inverter circuit; a frequency change-over circuit changing over the output frequency of the driver circuit; a choke coil controlling the high frequency output of an inverter; and a parallel circuit of a high pressure discharge lamp directly connected to the choke coil and a capacitor, and the frequency change-over circuit alternately changes over a first frequency belonging to a frequency band not containing an acoustic resonance frequency inherent to the high pressure discharge lamp and a second frequency higher than the first frequency, and a period of the first frequency is set longer than a period of the second frequency. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a high-pressure discharge lamp lighting device for lighting a high-pressure discharge lamp at a high frequency.
[0002]
[Prior art]
In a conventional high pressure discharge lamp lighting device, after power is turned on, before and after a high pressure discharge lamp (hereinafter, referred to as a "lamp") starts discharging, a starting pulse is generated or the control of the lighting frequency is switched ( For example, see Patent Documents 1 to 4.
[0003]
[Patent Document 1]
JP-A-4-342990
[Patent Document 2]
JP-A-6-243982
[Patent Document 3]
Japanese Patent No. 3279322
[Patent Document 4]
Japanese Patent No. 2946389
[0004]
[Problems to be solved by the invention]
The conventional device is configured as described above, and has the following problems.
[0005]
In order to generate a start pulse before and after the start of discharge and to switch the control of the lighting frequency, a detection circuit for detecting the start of discharge is required. As a result, in addition to the cost of the apparatus, depending on the accuracy of the detection circuit, there have been problems such as shifting to control after the start of discharge even though discharge has not completely started.
[0006]
The present invention has been made in order to solve such problems, and an object of the present invention is to provide a high-pressure discharge lamp lighting device that performs an inexpensive and reliable operation.
[0007]
[Means for Solving the Problems]
A high-pressure discharge lamp lighting device according to the present invention includes a DC power supply circuit for converting an AC power supply to DC, an inverter circuit for converting an output of the DC power supply circuit to a high frequency, a driver circuit for driving the inverter circuit, and an output frequency of the driver circuit. Switching circuit, a choke coil for adjusting the high-frequency output of the inverter, and a parallel circuit of a high-pressure discharge lamp and a capacitor connected in series to the choke coil. A first frequency belonging to a frequency band not including the acoustic resonance frequency and a higher second frequency are alternately switched, and the period of the first frequency is set longer than the period of the second frequency. It is what was constituted.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a circuit configuration of the high pressure discharge lamp lighting device according to the present embodiment.
In the figure, a DC power supply circuit 2 converts an AC voltage from a commercial power supply 1 into DC, and an output of the DC power supply circuit 2 is converted into high-frequency power by an inverter circuit 3.
[0009]
Specifically, the DC power supply circuit 2 employs a voltage doubler rectifier circuit including diodes 2a and 2b and smoothing capacitors 2c and 2d. The inverter circuit 3 includes two MOSFETs 3a and 3b that are turned ON / OFF alternately based on the frequency output from the driver circuit 4, and converts DC power into high-frequency power. The high-frequency power is adjusted in current by a choke coil 6 via a DC cut capacitor 5 and applied to a lamp 7 and a resonance capacitor 8. In the present embodiment, a ceramic metal halide lamp having a rating of 20 W is used as the lamp 7.
[0010]
The frequency switching circuit 9 switches the output frequency f of the driver circuit 4 based on the output of a built-in timer. FIG. 2 shows how the frequency switching circuit 9 according to the present embodiment switches the output frequency of the driver circuit 4. In the figure, the output frequency f is switched periodically and alternately between two different frequencies f1 and f2. In one cycle (T), the period during which the output frequency is f2 is d, and the other period (= T−d) is f1.
[0011]
Here, the output frequency f1 is a frequency suitable for lighting the lamp 7 after the discharge is started, and the output frequency f2 is a voltage for applying a high voltage to break the insulation between the electrodes of the lamp 7 before the discharge is started. It is a suitable frequency. Hereinafter, the setting of the output frequency f1, the output frequency f2, the cycle T, and the period d will be described.
[0012]
Generally, when a high-pressure discharge lamp is operated at high frequency, it is known that a so-called acoustic resonance phenomenon that causes a discharge arc to bend due to the interference between a traveling wave of a sound wave and a reflected wave in the lamp and causes extinguishing or lamp breakdown is likely to occur. I have. Therefore, particularly at the time of high-frequency lighting of 1 kHz or more, a non-resonant frequency band in which an acoustic resonance phenomenon does not occur is selected for lighting. FIG. 3 shows a distribution of a non-resonant frequency band and a resonance frequency band (frequency band where an acoustic resonance phenomenon occurs) of a ceramic metal halide lamp rated at 20 W used in the present embodiment. The figure also shows the relationship between the frequency f and the admittance Y of the high frequency section in the circuit configuration shown in FIG.
[0013]
Here, the high-frequency section is a section including the DC cut capacitor 5, the choke coil 6, the lamp 7, and the resonance capacitor 8.
In the drawing, Lc and Ls are characteristic curves showing the relationship between the frequency f and the admittance Y before and after the lamp 7 starts discharging, respectively. Rc and Rs are resonance points in the characteristic curves Lc and Ls, respectively, and the resonance point Rs has a lower frequency than the resonance point Rc.
[0014]
As described above, the characteristic curve greatly differs between before and after the start of the discharge, because the impedance of the lamp 7 is infinite before the start of the discharge, but decreases to a low level after the start of the discharge. It depends on.
[0015]
That is, the high-frequency portion before the start of discharge is represented by a series circuit of the DC cut capacitor 5, the choke coil 6, and the resonance capacitor 8, but in an actual circuit configuration, the DC cut capacitor 5 is more sufficient than the resonance capacitor 8. Because of the large capacitance, the characteristic curve Lc shows the characteristic dominated by the choke coil 6 and the resonance capacitor 8.
[0016]
On the other hand, the high-frequency portion after the start of discharge is represented by a circuit in which the DC cut capacitor 5 and the choke coil 6 are connected in series to the parallel connection portion of the lamp 7 and the resonance capacitor 8, but in an actual circuit configuration, The impedance of the lamp 7 is sufficiently smaller than the impedance of the resonance capacitor 8, the impedance of the parallel coupling portion of the lamp 7 and the resonance capacitor 8 is ignored, and the characteristic curve Ls is governed by the DC cut capacitor 5 and the choke coil 6. Is shown.
[0017]
In setting the output frequency f1, it is necessary to set the output frequency f1 to be higher than the resonance point Rs of the curve Ls, in a lag phase region, and to belong to a non-resonance frequency band.
[0018]
In order to obtain the rated lamp power by setting the output frequency f1 to 45 kHz included in the non-resonant frequency band of (42 to 50) kHz, the capacity of the DC cut capacitor 5 is 0.1 μF, and the capacity of the choke coil 6 is 1.3 mH. And The resonance point Rs at this time is about 14 kHz. The output frequency f1 is desirably set to 40 kHz or higher in order to avoid the possibility of overlapping with the operating frequency band of the television remote controller or the like. In the present embodiment, f1 is set to a non-resonant frequency band of (30 to 38) kHz. Was set to avoid.
[0019]
The output frequency f2 is set so that the admittance is large (close to the resonance point Rc of the characteristic curve Lc) and belongs to the non-resonance frequency band in order to apply a high voltage to both ends of the resonance capacitor 8.
In consideration of the distribution of the resonance frequency band and the non-resonance frequency band and the characteristic curve Lc of the 20 W ceramic metal halide lamp, the non-resonance frequency band (79 to 83) is used as a frequency that satisfies both conditions (high admittance and belongs to the non-resonance frequency band). Set 80 kHz belonging to kHz.
[0020]
The period T may be such that the switching operation between the output frequency f1 and the output frequency f2 cannot be visually recognized. However, it is desirable that the period T be 1 second or less in order to expedite the start of discharge.
[0021]
It is sufficient for the period d to have a width of several μsec to several msec. However, it is desirable to set the period d to be as short as possible, since the shorter the period d, the less likely it is for a light step to occur due to the switching operation after the start of discharge.
[0022]
In summary, the output frequency f1 was set to 45 kHz, the output frequency f2 was set to 80 kHz, the cycle T was set to 10 msec, and the period d was set to 1 msec in a 20 W ceramic metal halide lamp. FIG. 4 shows changes in the lamp current iL and the lamp voltage VL with respect to the output frequency f at this time. From the figure, it can be seen that before the lamp starts discharging, a high voltage is applied to the lamp 7 by the action of the output frequency f2, and after starting the discharge, the lamp 7 is lit mainly by the output frequency f1.
[0023]
As described above, since the control circuit of the output frequency is not changed before and after the start of the discharge and the circuit is configured to perform both the discharge start operation and the stable lighting operation, a detection circuit is not required, and an inexpensive and simple lighting device is provided. can do.
[0024]
In addition, even if some kind of discharge instability occurs during stable lighting and the light goes out, the operating state can be the same as the state before the start of discharge without providing a special detection circuit or additional control, and the lighting can be reliably restored. Becomes possible.
[0025]
Embodiment 2 FIG.
In the first embodiment, the case where the output frequency f2 is set in the non-resonant frequency band has been described. In the present embodiment, the case where the output frequency f2 is set in the resonance frequency band will be described.
FIG. 5 shows the distribution of the resonance frequency band and the non-resonance frequency band, the relationship between the frequency f and the admittance Y of the high frequency part, and the setting of the output frequency f2 according to the present embodiment, similarly to FIG. It is shown.
The circuit configuration and operation are the same as those in the first embodiment, and a description thereof will be omitted. The difference from the first embodiment lies in the setting of the output frequency f2 and the period d.
[0026]
Generally, when a high-pressure discharge lamp is turned on at a high frequency, it is known that it takes about 1 msec from when the output frequency is shifted from the non-resonant frequency band to the resonant frequency band until the acoustic resonance phenomenon occurs. Therefore, conversely, even if the frequency f2 belongs to the resonance frequency band, if the frequency f1 is switched to the frequency f1 belonging to the non-resonance frequency band within the period d within 1 msec, the acoustic resonance phenomenon does not occur and the switching operation is performed stably. It is expected to continue.
The present embodiment is based on such consideration, in which the output frequency f2 is set to an arbitrary frequency near the resonance point Rc, and the period d is set within 1 msec.
[0027]
With the above configuration, the setting range of the output frequency f2 is extended to the resonance frequency band. As a result, the degree of freedom in design is increased. In particular, by setting the output frequency f2 to be high, the capacitance of the resonance capacitor 8 can be reduced and the size can be further reduced.
[0028]
Embodiment 3 FIG.
In the first and second embodiments, the case where the output frequency f2 is a single frequency has been described. In the present embodiment, a case where the output frequency f2 is not a single frequency will be described.
FIG. 6 is a block diagram showing a circuit configuration of the high pressure discharge lamp lighting device according to the present embodiment.
In the figure, 1 to 9 are the same as those shown in the first embodiment, and therefore the description is omitted. In the present embodiment, a timer circuit 10 is newly provided in addition to the timer built in the frequency switching circuit 9.
[0029]
Next, the operation will be described.
Generally, electronic components such as coils and capacitors have variations in their characteristic values (capacities), and the resonance points Rs and Rc shown in FIG. 3 deviate due to the variations. Since the output frequency f1 is set at a gentle place away from the resonance point Rs, even if the resonance point Rs is slightly shifted, the admittance hardly changes and does not pose a problem.
[0030]
On the other hand, the output frequency f2 needs to be set near the resonance point Rc having a large admittance in order to generate a high voltage. As a result, if the resonance point Rc deviates even a little, the admittance greatly changes, and the voltage applied to the lamp greatly changes before the start of discharge. In particular, when the resonance point Rc shifts in the direction in which the applied voltage decreases, it is assumed that discharge cannot be started.
[0031]
In order to avoid such a situation, for example, as shown in FIG. 7, the frequency f2 is alternately switched to two different frequencies f21 and f22 at a cycle determined by the timer circuit 10.
Here, the frequencies f21 and f22 are both selected from the vicinity of the resonance point Rc, and the admittance of one of the frequencies is set to be a predetermined value or more even if the resonance point Rc is slightly shifted.
[0032]
Hereinafter, this point will be described in detail.
FIG. 8 shows the relationship between the frequency f and the voltage applied to the lamp 7 before starting the discharge.
Since the voltage applied to the lamp 7 is substantially proportional to the admittance Y of the high-frequency part, the characteristic curve shown in FIG. 8 is substantially similar to the characteristic curve Lc showing the relationship between the frequency f and the admittance Y shown in FIG. It becomes.
In the figure, LVc indicates a characteristic curve when the characteristic value of each component is at the center of the variation (center value). LVc 'indicates a characteristic curve when the characteristic value (capacitance value) of the choke coil 6 is larger than the center value by several percent, for example. Vig indicates the minimum applied voltage required for the lamp to start discharging.
[0033]
As shown in the drawing, if the voltages of the characteristic curves LVc and LVc '(the voltages corresponding to the points A and B) with respect to the frequency f2 are VA and VB, respectively, VA>Vig> VB, and in the characteristic curve LVc based on the center value, Even if the minimum voltage Vig is cleared, if the parts have a variation of several percent, the resonance point Rc shifts, and the applied voltage greatly decreases, and it can be seen that the voltage does not reach the minimum voltage Vig. Conversely, if the frequency f2 'is selected such that the voltage of the curve LVc' (the voltage corresponding to the point C) reaches the minimum voltage Vig, the voltage (the voltage corresponding to the point D) for the frequency f2 'of the curve LVc becomes minimum. It can be seen that the voltage does not reach Vig.
When the output frequency f2 is a single frequency in this way, it is difficult to secure the minimum applied voltage Vig even when parts vary. Therefore, in this case, it is necessary to switch the output frequency f2 to a plurality of values.
[0034]
FIG. 9 shows a possible range of the characteristic curve LVc when component variations are considered.
Here, LVmin and LVmax are characteristic curves LVc when the resonance point RVc varies from the lowest to the highest, respectively. As shown in the figure, a frequency fmin corresponding to a point E at which a voltage [Vig + α] (where α> 0) is provided on the characteristic curve LVmin is defined as a frequency f21, and a point F at which a voltage [Vig + α] is provided on the characteristic curve LVmax. The corresponding frequency fmax is defined as a frequency f22. If these are switched periodically, one of the frequencies f21 and f22 always becomes a frequency that gives a voltage exceeding the voltage Vig, regardless of the position of the curve LVc, and the discharge is started reliably. be able to.
[0035]
When the frequency fmin and the frequency fmax are far apart from each other, as shown in FIG. 10, fmin = f21 and fmax = f2n to divide f21 and f2n into n frequencies (f21, f22,...). f2n) may be set so that the frequency is sequentially switched, and the operation of sequentially switching may be periodically repeated.
[0036]
In this manner, by setting a plurality of frequencies as the output frequency f2 and periodically repeating the operation of sequentially switching these, it is possible to reliably obtain a lamp voltage for starting discharge even when the characteristic values of the circuit components vary. it can.
[0037]
Embodiment 4 FIG.
In the third embodiment, a case has been described in which a plurality of frequencies are set as the output frequency f2, and the operation of sequentially switching these is periodically repeated, but in the present embodiment, the output frequency f2 is smoothly and continuously lowered. The case will be described.
FIG. 11 is a block diagram showing a circuit configuration of the high pressure discharge lamp lighting device according to the present embodiment. In the figure, 1 to 9 are the same as those shown in the first embodiment, and therefore the description is omitted. In the present embodiment, a sweep circuit 11 is newly added. The sweep circuit 11 operates so as to gradually lower the output frequency of the frequency switching circuit 9 over a predetermined time from when the commercial power supply 1 is turned on.
[0038]
FIG. 12 shows the output frequency f of the driver circuit 4 with respect to the elapsed time from when the commercial power is turned on. The output frequency f2 is gradually lowered while the output frequency f1 is kept constant. The lower limit of the output frequency f2 is equal to or lower than the output frequency fmin in the third embodiment.
As a result, the discharge is started at the moment when the lamp applied voltage before the start of the discharge exceeds a predetermined value, so that the discharge can be started irrespective of the variation of the components constituting the circuit.
[0039]
As described above, since the output frequency f2 is continuously and gradually decreased, the lamp voltage for starting the discharge can be reliably ensured regardless of the variation of the components. Conversely, the same effect can be obtained even if the output frequency f2 is continuously and gradually increased.
Further, since the output frequency f2 can be delayed in all periods, the stress on the MOSFETs 3a and 3b constituting the inverter circuit 3 can be reduced, and the reliability of the circuit can be further improved. .
[0040]
Embodiment 5 FIG.
In the first to fourth embodiments, the case where the output frequency is alternately switched between f1 and f2 by the timer built in the frequency switching circuit 9 has been described. In the present embodiment, the output frequency is synchronized with the cycle of the commercial power supply 1. The case where the switching is performed will be described.
FIG. 13 is a block diagram showing a circuit configuration of the high pressure discharge lamp lighting device according to the present embodiment.
In the figure, 1 to 9 are the same as those shown in the first embodiment, so that the description thereof will be omitted and different points will be described. In the present embodiment, a power supply voltage detection circuit 12 is newly added. The power supply voltage detection circuit 12 monitors the output voltage Vdc of the DC power supply circuit 2 and acts on the frequency switching circuit 9 according to the value of the output voltage Vdc.
[0041]
Next, the operation will be described.
FIG. 14 shows the relationship between the output voltage Vdc and the output frequency f. The output of the DC power supply circuit 2 is generally a substantially DC voltage having a ripple synchronized with the commercial power supply 1. The power supply voltage detection circuit 12 acts on the frequency switching circuit 9 so as to output the output frequency f2 at the moment when the output voltage Vdc exceeds a predetermined value.
[0042]
As a result, the frequency switching circuit 9 can always output the output frequency f2 at the peak of the output of the DC power supply circuit 2, and can reliably secure the lamp voltage for starting discharge.
Although the output voltage of the commercial power supply usually has a variation of about ± several%, a constant discharge start voltage can be always obtained even if the output of the commercial power supply 1 varies.
[0043]
In the present embodiment, a configuration is described in which a voltage at which discharge is started is obtained by the resonance voltage of the choke coil 6 and the resonance capacitor 8. However, as shown in FIG. The same effect can be obtained even by using the pulse superposition type starting circuit 13 used.
[0044]
Embodiment 6 FIG.
In the first to fifth embodiments, the configuration is such that the output frequency f1 is not changed. However, in the present embodiment, a configuration in which the output frequency f1 is increased as the voltage of the lamp 7 is increased will be described.
FIG. 16 is a block diagram showing a circuit configuration of the high pressure discharge lamp lighting device according to the present embodiment.
In the figure, the settings of 1 to 9 and the output frequency f2 are the same as those described in the first and second embodiments, and thus the description is omitted. In the present embodiment, a lamp voltage detection circuit 14 is newly added.
[0045]
Next, the operation will be described.
The lamp voltage detection circuit 14 detects the effective value of the lamp voltage, and inputs this to the frequency switching circuit 9. The frequency switching circuit 9 outputs f11 as the output frequency f1 when the detected effective value is equal to or lower than the predetermined value, and outputs f12 when the detected effective value is equal to or higher than the predetermined value. Here, as shown in FIG. 17, the frequencies f11 and f12 both belong to the non-resonant frequency band (30 to 38 KHz) and satisfy the relationship of (frequency f11) <(frequency f12). In this non-resonant frequency band (30 to 38 KHz), the admittance monotonically decreases as the frequency increases, so that the lamp applied voltage proportional to the admittance is higher at the frequency f11 than at f12. As a result, a high voltage is applied to the lamp when the voltage is equal to or less than a predetermined value, and a low voltage is applied to the lamp when the voltage is equal to or more than the predetermined value.
[0046]
In general, high-pressure discharge lamps have a lamp impedance that increases in accordance with the cumulative lighting time, but the lamp voltage increases slightly more than the lamp current decreases due to the progress of the life. It is known that the lamp power is increased by about 10% from that at the beginning of the life.
In the present embodiment, control is performed to keep the power constant based on the deterioration of the lamp, in which the lamp power increases with such a temporal change.
[0047]
As described above, when the lamp voltage at the beginning of the life is low, f11 is output as the output frequency f1 to set a relatively large lamp current, and when the lamp voltage at the end of the life is high, f12 is output as the output frequency f1. Thus, the lamp current is set to be low to keep the lamp power almost constant.
[0048]
In this embodiment, the output frequency f1 has two values. However, the output frequency f1 may have a plurality of values, or may be monotonically increased with respect to the lamp voltage. However, also in this case, the range that the output frequency f1 can take needs to belong to the non-resonant frequency band.
Also, the frequency f2 has been described as a fixed value, but it is also possible to follow the fluctuation of the output frequency f12 and the output frequency f11.
[0049]
As described above, the value of the output frequency f1 is varied by the lamp voltage, so that the lamp power can be appropriately maintained while achieving the effects described in the first to fifth embodiments.
[0050]
In the first to sixth embodiments, a half-bridge type circuit is shown as a means for applying high-frequency power to the lamp 7, but a push-pull type, a single-pole voltage resonance type or the like may be used.
Further, although the voltage doubler rectifier circuit is used as the DC power supply circuit 2, a full-wave rectifier circuit, a boost converter, or the like may be used.
[0051]
Further, in the first to sixth embodiments, the output frequency f1 is set to a non-resonant frequency band around the output frequency of 45 kHz, but the lighting can be performed in the same manner even when the output frequency f1 is set to another non-resonant frequency band.
Furthermore, in the above-described first to sixth embodiments, a metal halide lamp having a rated power of 20 W having a ceramic arc tube is used, but an arc tube of another material or a lamp having another rated power has the same circuit configuration and The lamp can be turned on using the control method.
[0052]
Embodiment 7 FIG.
In the first to sixth embodiments, the case where the illuminable lamp is mounted has been described. In the present embodiment, protection in a case where the lamp cannot be turned on immediately after the lamp is turned off or a case where the lamp is not mounted will be described. FIG. 18 is a block diagram showing a circuit configuration of the high-pressure discharge lamp lighting device according to the present embodiment. In the figure, 1 to 9 are the same as those shown in the first embodiment, and therefore the description is omitted. In the present embodiment, a thermistor 15 for detecting the temperature of the mold of the MOSFET 3b is newly added. As shown in FIG. 19, the thermistor 15 controls so that the output of the inverter circuit 3 is stopped when the temperature of the MOSFET 3b becomes higher than a predetermined value, and is restarted when the temperature becomes lower than the predetermined value.
[0053]
Generally, a high-pressure discharge lamp cannot be re-lit for several minutes after the light is turned off due to a high gas pressure inside the arc tube.
It is known that in the case of the lamp of the rated 20 W class taken up in the present embodiment, it cannot be turned on again for about 2 to 5 minutes after the light is turned off. During this time, the operation of the inverter circuit 3 continues the state of the first half shown in FIG. 4 for several minutes. At this time, during the period when the output frequency is f1, the MOSFETs 3a and 3b operate in the advanced phase state, so that the temperature rise of these MOSFETs is larger than that during normal lighting. Also, when the commercial power supply 1 is turned on with the lamp not mounted (not mounted), the state in the first half of FIG. 4 is continued.
[0054]
Therefore, with the above-described configuration using the thermistor 15, if the lamp is turned off, the operation in FIG. 19 is repeated for several minutes and then turned on again. If the lamp is not mounted, the operation in FIG. 19 is continued. In any case, since the temperature of the MOSFET 3b or 3a is controlled so as not to become a predetermined value or more, heat generation of the circuit can be prevented.
[0055]
In any of the above cases, a heat radiation fin may be attached to the MOSFETs 3a and 3b, or may be brought into contact with a metal case that covers the device to dissipate heat, and the time required to reach a predetermined temperature may be adjusted.
That is, the temperature may not reach the predetermined temperature for several minutes in the case of relighting, and may be adjusted so as to reach the predetermined temperature only when the operation without the lamp is continued for several tens of minutes.
[0056]
Further, in the case of the setting for distinguishing between the time of re-lighting and the time of non-mounting of the lamp as described above, as shown in FIG. 20, once the temperature reaches a predetermined temperature, the light may be kept off. .
[0057]
Embodiment 8 FIG.
This embodiment shows another configuration example for realizing protection in a case where the lamp described in Embodiment 7 cannot be turned on immediately after turning off or a case where the lamp is not mounted.
FIG. 21 is a block diagram showing a circuit configuration of the high pressure discharge lamp lighting device according to the present embodiment. In the figure, reference numerals 1 to 9 are the same as those shown in the seventh embodiment, and therefore description thereof is omitted.
[0058]
In the figure, a smoothed voltage smoothed by a DC power supply circuit 2 is divided by a resistor 16 and a thermistor 15 and input to a base of a transistor 17. Here, a PTC thermistor having a positive temperature characteristic is used as the thermistor 15, and a transistor with a built-in resistor is used as the transistor 17. The terminal 18 is a shutdown terminal when a driver IC or the like is used for the driver circuit 4. When the transistor 17 is off, the driver circuit 4 is driven. When the transistor 17 is on, the driver circuit 4 stops outputting. The output of the inverter circuit 3 is stopped.
[0059]
During normal lighting, the temperature of the MOSFET 3b is low and the resistance value of the PTC thermistor is small, so that the transistor 17 maintains the OFF state. However, when the state of the first half shown in FIG. 4 continues and the temperature of the MOSFET 3b exceeds a predetermined value, the resistance value of the PTC thermistor 15 increases, the transistor 17 turns on, and the driver circuit 4 stops. Since the transistor 17 is a transistor with a built-in resistor, it is turned on / off according to the base voltage. However, since the turn-off voltage is higher than the turn-on voltage, a certain degree of hysteresis can be provided and the non-operating state is maintained. be able to.
[0060]
In an actual circuit configuration, a device having a turn-on voltage of 3 V and a turn-off voltage of 0.5 V is used. A capacitor 19 is connected to stabilize the operation of the transistor 17.
As described above, by using the PTC thermistor as the thermistor 15, it is possible to perform control when the lamp is not turned on with a simple configuration.
[0061]
The driver circuit 4 may be stopped once and then restarted according to the temperature of the thermistor 15 as shown in FIG. 19, or may be stopped regardless of the temperature as shown in FIG. good.
In the seventh or eighth embodiment, the portion where the thermistor 15 is brought into contact is not necessarily the MOSFET 3b, and the same effect can be obtained even with the MOSFET 3a, the choke coil 6, and the like.
[0062]
Embodiment 9 FIG.
In the seventh and eighth embodiments, the case where the lamp 7 can be attached to and detached from the lighting circuit has been described. In the present embodiment, the case where the lighting circuit and the lamp are integrated will be described.
FIG. 22 is a block diagram showing a circuit configuration of the high pressure discharge lamp lighting device according to the present embodiment.
In the figure, 1 to 9 are the same as those shown in the first embodiment, and the description thereof will be omitted, and different points will be described. In the present embodiment, a thermal fuse 20 is newly added. The thermal fuse 20 is inserted into the gate of the MOSFET 3a and is mounted in contact with the main body mold portion.
When the temperature of the MOSFET 3a rises as the first half shown in FIG. 4 continues, the gate signal of the MOSFET 3a is cut off and the operation of the inverter circuit 3 is stopped.
[0063]
FIG. 23 is a cross-sectional view of a light bulb-shaped lighting device in which the lamp 7 and the lighting circuit are integrated.
The commercial power supply 1 is turned on from the base 21, and the portion excluding the commercial power supply 1 and the lamp 7 in FIG. 22 is mounted on the lighting circuit board 22 and connected to the lamp 7. The partition plate 23 separates the lamp 7 from the lighting circuit board 22, and the cover 24 and the globe 25 cover the lamp 7, the lighting circuit board 22 and the partition plate 23, and have a shape similar to an incandescent lamp as a whole.
[0064]
The operating temperature of the thermal fuse 20 is selected such that it does not operate in the non-lighting state for several minutes immediately after the lamp is turned off, and operates only when the non-lighting state continues longer than that.
As described above, in a device in which the lamp and the lighting circuit are integrated and the lamp cannot be replaced, if the lamp cannot be turned on, the lighting circuit cannot be restarted so that unnecessary power is not consumed. .
[0065]
In this embodiment, the temperature fuse 20 is connected to the gate terminal of the MOSFET 3a. However, if the lighting circuit cannot function, the drain terminal of the MOSFET 3a, the constant voltage source of the driver circuit 4, the DC power supply circuit 2 May be inserted into other parts such as the output point of Further, the parts to be brought into contact are not limited to those shown in FIG. 22, but may be any parts where the temperature rises significantly when the lamp is not lit.
【The invention's effect】
A high-pressure discharge lamp lighting device according to the present invention includes a DC power supply circuit for converting an AC power supply to DC, an inverter circuit for converting an output of the DC power supply circuit to a high frequency, a driver circuit for driving the inverter circuit, and an output frequency of the driver circuit. Switching circuit, a choke coil for adjusting the high-frequency output of the inverter, and a parallel circuit of a high-pressure discharge lamp and a capacitor connected in series to the choke coil. A first frequency belonging to a frequency band not including the acoustic resonance frequency and a higher second frequency are alternately switched, and the period of the first frequency is set longer than the period of the second frequency. With this configuration, a circuit for detecting the start of discharge is not required, the discharge can be started reliably, and the apparatus can be reduced in size and cost.
ADVANTAGE OF THE INVENTION The high pressure discharge lamp lighting device which concerns on this invention does not need a starting part and the power supply line and signal line for drive-controlling this, it can start discharge reliably, and the size reduction of a device and cost reduction Can be achieved.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing how the frequency switching circuit according to Embodiment 1 of the present invention switches the output frequency of a driver circuit.
FIG. 3 is a diagram illustrating a distribution of a resonance frequency band and a non-resonance frequency band, and a relationship between an output frequency and admittance in a 20W ceramic metal halide lamp according to the first embodiment of the present invention.
FIG. 4 is a diagram illustrating a relationship between an output frequency, a lamp current, and a lamp voltage in the 20W ceramic metal halide lamp according to the first embodiment of the present invention.
FIG. 5 is a diagram illustrating a distribution of a resonance frequency band and a non-resonance frequency band and a relationship between an output frequency and admittance in a 20W ceramic metal halide lamp according to a second embodiment of the present invention.
FIG. 6 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to Embodiment 3 of the present invention.
FIG. 7 is a diagram showing a state where a frequency switching circuit according to a third embodiment of the present invention switches an output frequency of a driver circuit.
FIG. 8 is a diagram illustrating a distribution of a resonance frequency band and a non-resonance frequency band, and a relationship between an output frequency and admittance, in a 20W ceramic metal halide lamp according to a third embodiment of the present invention.
FIG. 9 is a diagram illustrating the distribution of the resonance frequency band and the non-resonance frequency band and the relationship between the output frequency and the admittance in the 20W ceramic metal halide lamp according to the third embodiment of the present invention.
FIG. 10 is a diagram showing a state where a frequency switching circuit according to a third embodiment of the present invention switches an output frequency of a driver circuit.
FIG. 11 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to a fourth embodiment of the present invention.
FIG. 12 is a diagram showing a state where a frequency switching circuit according to a fifth embodiment of the present invention switches an output frequency of a driver circuit.
FIG. 13 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to Embodiment 5 of the present invention.
FIG. 14 is a diagram showing a state where a frequency switching circuit according to a fifth embodiment of the present invention switches an output frequency of a driver circuit.
FIG. 15 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to Embodiment 5 of the present invention.
FIG. 16 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to Embodiment 6 of the present invention.
FIG. 17 is a diagram illustrating a distribution of a resonance frequency band and a non-resonance frequency band, and a relationship between an output frequency and admittance in a 20W ceramic metal halide lamp according to a sixth embodiment of the present invention.
FIG. 18 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to Embodiment 7 of the present invention.
FIG. 19 is a diagram illustrating the relationship between the temperature of the MOSFET and the operation of the inverter circuit according to the seventh embodiment of the present invention.
FIG. 20 is a diagram illustrating the relationship between the temperature of the MOSFET and the operation of the inverter circuit according to the seventh embodiment of the present invention.
FIG. 21 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to Embodiment 8 of the present invention.
FIG. 22 is a block diagram showing a circuit configuration of a high pressure discharge lamp lighting device according to Embodiment 9 of the present invention.
FIG. 23 is a cross-sectional view of a light bulb-shaped lighting device in which a lamp and a lighting circuit according to Embodiment 9 of the present invention are integrated.
[Explanation of symbols]
1 Commercial power supply
2 DC power supply circuit
2a, 2b diode
2c, 2d Smoothing capacitor
3 Inverter circuit
3a, 3b MOSFET
4 Driver circuit
5 DC cut capacitor
6 choke coil
7 lamp
8 Resonant capacitor
9 Frequency switching circuit
10 Timer circuit
11 Sweep circuit
12 Power supply voltage detection circuit
13 Starting circuit
14. Lamp voltage detection circuit
15 Thermistor
20 Thermal fuse

Claims (12)

A DC power supply circuit for converting the AC power supply to DC;
An inverter circuit for converting the output of the DC power supply circuit to a high frequency;
A driver circuit for driving the inverter circuit;
A frequency switching circuit for switching an output frequency of the driver circuit;
A choke coil for adjusting a high-frequency output of the inverter;
A parallel circuit of a high-pressure discharge lamp and a capacitor connected in series to the choke coil,
The frequency switching circuit,
A first frequency belonging to a frequency band not including an acoustic resonance frequency unique to the high-pressure discharge lamp and a second frequency higher than this are alternately switched,
A high pressure discharge lamp lighting device, wherein the period of the first frequency is set longer than the period of the second frequency. A DC voltage detection circuit for extracting a synchronization signal synchronized with the AC power supply from an output voltage of the DC power supply circuit,
The high pressure discharge lamp lighting device according to claim 1, wherein the first frequency and the second frequency are alternately switched by using the synchronization signal as a trigger. The second frequency is
The high pressure discharge lamp lighting device according to claim 1, wherein the high pressure discharge lamp belongs to a frequency band that does not include an acoustic resonance frequency unique to the high pressure discharge lamp. The second frequency is
4. The high pressure discharge lamp lighting device according to claim 1, wherein the high frequency discharge lamp lighting device is set near a resonance frequency determined by the choke coil and the capacitor. The period of the second frequency is
The high pressure discharge lamp lighting device according to any one of claims 1 to 4, wherein the time is set to be equal to or less than a time required for causing an acoustic resonance phenomenon. The second frequency is
The high pressure discharge lamp lighting device according to any one of claims 1 to 5, wherein the high pressure discharge lamp lighting device is periodically changed. The high pressure discharge lamp lighting device according to any one of claims 1 to 5, wherein the second frequency is monotonously decreased. A high-frequency voltage detection circuit for detecting the voltage between both ends of the high-pressure discharge lamp is provided,
8. The high pressure discharge lamp lighting device according to claim 1, wherein the first frequency is increased in response to an increase in the output of the high frequency voltage detection circuit. 9. The high pressure discharge lamp lighting device according to claim 8, wherein the variation range of the first frequency is set within a frequency band not including an acoustic resonance frequency unique to the high pressure discharge lamp. Temperature detecting means for detecting a temperature by contacting a circuit component constituting the high pressure discharge lamp lighting device is provided, and when detecting that the temperature of the circuit component has reached a predetermined temperature or higher, the output of the inverter circuit is detected. Stop it,
The high pressure discharge lamp lighting device according to any one of claims 1 to 9, wherein the inverter circuit is restarted when the temperature of the circuit component falls below a predetermined value. Temperature detecting means for detecting the temperature by contacting the circuit components constituting the high pressure discharge lamp lighting device, and thereby detecting when the temperature of the circuit components reaches a predetermined temperature or higher, a circuit connection constituting the device; The high-pressure discharge lamp lighting device according to any one of claims 1 to 10, wherein a part of the device is disconnected to stop the output of the inverter circuit. The circuit component is:
The high-pressure discharge lamp lighting device according to any one of claims 10 to 11, wherein the switching device is a switching element included in the inverter circuit.

Images