JP2008004338A - High-intensity discharge lamp lighting device, and illumination apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-intensity discharge lamp lighting device of half-bridge formation in which increase in component stress, enlargement of components and increase in cost are prevented, unstable lamp gas condition at the time of lamp starting becomes allowable, and stable lighting at the time of lamp lighting becomes possible. <P>SOLUTION: The lighting device has a half-bridge formation, and is equipped with a series circuit consisting of switching elements Q1, Q2 and a series circuit consisting of capacitors C1, C2 wherein both the circuits are connected to a DC power source 1 in parallel. The lighting device is also equipped with the high-intensity discharge lamp DL which is connected between a connection point between the switching elements Q1, Q2, and a connection point between the capacitors C1, C2 through an inductor L3. The lighting device further includes an electric power control means 52 to 54 which control electric power supplied to the high-intensity discharge lamp DL by controlling the switching elements Q1, Q2; and a voltage adjusting means 51 which adjusts voltages between respective both ends of the respective capacitors C1, C2, in such a way that the voltages differ mutually when turning off the high-intensity discharge lamp DL and the voltages become approximately equivalent, when turning on the high-intensity discharge lamp DL. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high pressure discharge lamp lighting device for lighting a high pressure discharge lamp using a switching power supply and a lighting fixture using the same.

  Conventionally, a high-pressure discharge lamp lighting device having a half-bridge configuration as shown in FIG. 11 is known. Generally, electrolytic capacitors having the same capacity are used for the capacitors C1 and C2 having a half bridge configuration. However, in Patent Document 1 (Japanese Patent Laid-Open No. 2004-303789), the capacitors C1 and C2 are set to have different capacities. It has been proposed to do. In this case, when switching elements Q1 and Q2 are controlled as shown in FIG. 12, capacitors C1 and C2 are charged to different voltages as shown by Vc1 and Vc2 in FIG. 12, and when discharge lamp DL is not lit, discharge lamp DL As shown by Vla in FIG. 12, the no-load secondary voltage applied across the two terminals has a waveform with a different voltage value depending on the polarity. When no load is applied, a high voltage pulse voltage generated by an igniter (not shown) is superimposed on the no-load secondary voltage.

In general, in order to start a high pressure discharge lamp, it is necessary to set the no-load secondary voltage to 270 V or more. However, in order to satisfy both polarities of 270 V or more, capacitors C1, C2 and switching elements Q1, Q2 The withstand voltage of the parts constituting the circuit is increased, resulting in an increase in the size and cost of the lighting device. Therefore, the no-load secondary voltage is changed depending on the polarity, and the capacities of the capacitors C1 and C2 are set so that at least one of the voltages is 270V or more.
Japanese Patent Laid-Open No. 2004-303789

  In the circuit of FIG. 11, the lamp voltage Vla and the voltages Vc1 and Vc2 of the capacitors C1 and C2 are detected by the detection circuits 52 and 57, and the switching elements Q1 and Q2 are controlled by the control circuit 50 as shown in FIG. As shown in the waveform diagram of FIG. 12, the voltage values Vc1 and Vc2 of the capacitors C1 and C2 during non-lighting and during lighting are set to be different values.

  Here, in order to light a high-pressure discharge lamp stably in general, a power supply voltage of about 1.5 to 2.0 times the lamp voltage is required. In addition, when the lamp temperature at the start of the lamp is not stable and the gas filled in the arc tube is not completely vaporized, the lamp impedance becomes unstable. It is necessary to set.

  In the circuit of FIG. 11, the power source for supplying power to the lamp corresponds to the capacitors C1 and C2. Therefore, in order to light the lamp stably, it is desirable to set the voltages of the capacitors C1 and C2 as high as possible. However, if the voltage is set too high, the device withstand voltage will increase, leading to an increase in the size and cost of the parts. Therefore, the lamp can be stably lit and the device withstand voltage should not be too high. Necessary.

  With the conventional technology, it is possible to keep the element breakdown voltage low, but there is a problem that lighting cannot be stably maintained with the polarity of the lower capacitor voltage.

  The present invention has been made in view of the above points, and can provide stable lighting at the time of starting the lamp and stable lighting without incurring an increase in component stress, an increase in size of the component, and an increase in cost. It is an object of the present invention to provide a high-pressure discharge lamp lighting device that enables this.

  In the present invention, in order to solve the above-mentioned problem, as shown in FIG. 1, a series circuit of first and second switching elements Q1, Q2 and first and second capacitors C1, C2 are provided. The series circuit is connected in parallel to the DC power source 1 and is connected via an inductor L3 between the connection point of the first and second switching elements Q1, Q2 and the connection point of the first and second capacitors C1, C2. The high-pressure discharge lamp lighting device for lighting the high-pressure discharge lamp DL is a power control means (52) for controlling the power supplied to the high-pressure discharge lamp DL by switching the first and second switching elements Q1, Q2. To 54) and the voltage adjusting means 5 for adjusting the voltage across the first and second capacitors C1, C2 to be different from each other when the high-pressure discharge lamp DL is not lit and to be substantially equal when lit. It is characterized in that it has and.

  According to the present invention, when the high pressure discharge lamp is not lit, the voltages of the two capacitors in the half-bridge configuration are set to different voltages, so that the no-load secondary voltage is increased in one polarity while the other polarity is In this case, the withstand voltage of the capacitor can be lowered, and when the high pressure discharge lamp is lit, the voltages of the two capacitors in the half-bridge configuration are made substantially equal to each other, so that stable lighting can be realized.

(Embodiment 1)
FIG. 1 is a circuit diagram of a high pressure discharge lamp lighting device according to Embodiment 1 of the present invention. Hereinafter, the circuit configuration will be described. The DC power supply 1 detects a diode bridge DB that full-wave rectifies the AC voltage of the commercial AC power supply Vs into a DC voltage, a boost chopper 11 that includes an inductor L11, a switching element (MOSFET in the figure) Q11, and a diode D11, and detects this output. The chopper control circuit 12 performs on / off control of the switching element Q11 so that the output becomes a predetermined voltage value E (for example, 460 V).

  A half bridge circuit 3 is connected to the output of the DC power supply 1. In the half bridge circuit 3, a series circuit of switching elements (MOSFETs in the figure) Q1 and Q2 and a series circuit of capacitors C1 and C2 are connected in parallel, and a connection point between the switching elements Q1 and Q2 and a capacitor C1, Between the connection point of C2, an inductor L3 and a high-pressure discharge lamp DL are connected in series, and a capacitor C3 is connected in parallel with the high-pressure discharge lamp DL. Further, an igniter IGN is interposed in series between the high pressure discharge lamp DL and the inductor L3 so as to form a closed circuit together with the capacitor C3 and the high pressure discharge lamp DL. The igniter IGN includes a pulse generation circuit PG and a pulse transformer PT, and generates a high voltage pulse when there is no load. Note that a low resistance for current detection may be inserted in series with the high-pressure discharge lamp DL.

  A control circuit 5 is connected to the half bridge circuit 3. The control circuit 5 controls the switching elements Q1 and Q2 to step down the output voltage E of the step-up chopper 11 to a predetermined voltage value required by the discharge lamp DL, and the lamp voltage is a rectangular wave voltage having a low frequency. The state of the discharge lamp DL is detected by the Vla detection circuit 52, and the lamp power Wla calculated by the Wla calculation circuit 53 is obtained in accordance with the detected state of the discharge lamp DL. Thus, the target value of the lamp current Ila is set, and the switching circuit Q1, Q2 is controlled by the drive circuit 54. In addition, a voltage adjustment circuit 51 that adjusts the voltage balance of the capacitors C1 and C2 during lighting is provided.

  Differences from the prior art will be described with reference to FIG. The voltage applied to both ends of the lamp is indicated as Vla, the voltages of the capacitors C1 and C2 are indicated as Vc1 and Vc2, and the driving signals of the switching elements Q1 and Q2 are indicated as Q1 and Q2. Note that the switching operation waveforms of the switching elements Q1 and Q2 in FIG. 2 are schematically shown. Actually, the switching frequency of the switching elements Q1 and Q2 is as shown in FIG. It becomes a higher frequency than the schematic diagram.

  When the discharge lamp is not lit, the voltage Vla applied to both ends of the lamp is an unbalanced no-load secondary voltage (for example, 300V and 160V) divided by the capacitance ratio of the capacitors C1 and C2, as in the prior art. It has become. At this time, the voltage adjustment circuit 51 is not operated. On the other hand, when the discharge lamp is turned on, the voltage adjustment circuit 51 is operated to adjust the voltage across the capacitors C1 and C2 to be substantially equal (for example, 230V).

  Whether or not to operate the voltage adjustment circuit 51 is determined, for example, by whether or not the discharge lamp is lit or not based on the output of the Vla detection circuit 52. When the discharge lamp is lit, the voltage adjustment circuit 51 is operated according to a command from the Wla arithmetic circuit 53. The voltage adjustment circuit 51 may be switched so as not to operate when not lit.

  In general, in a high pressure discharge lamp, in the starting process from the start of the lamp to the stabilization of the lamp voltage, the temperature of the arc tube is not stable, the discharge becomes unstable, and the lamp impedance fluctuates. In such a state, if a power supply voltage for supplying power to the lamp is not sufficiently secured, it is impossible to supply a sufficient current to the lamp, and in the worst case, the lamp is extinguished. Therefore, as shown in FIG. 2, after the lamp is lit, the discharge is stabilized by equalizing the voltages of the capacitors C1 and C2.

(Embodiment 1 ')
FIG. 3 shows an example of a specific circuit configuration for realizing the voltage adjustment of the capacitor during lighting according to the first embodiment. The control circuit 5 includes a microcomputer PIC12F675 (manufactured by Microchip). The microcomputer 55 has analog voltage input ports at the 6th and 7th pins, a binary output port at the 3rd and 4th pins, and an analog voltage output port at the 2nd pin. The first and eighth pins of the microcomputer 55 are connected to the control power supply voltage Vcc and the ground line, respectively.

  From the third and fourth pins of the microcomputer 55, as shown in FIG. 4, a low frequency signal of several tens to several hundreds Hz for determining the polarity inversion frequency is always output. This low frequency signal is used as one input of an AND gate for outputting control signals for the switching elements Q1 and Q2.

  Further, the 6th and 7th pins of the microcomputer 55 detect the divided voltages Vla1 and Vla2 from both ends of the high pressure discharge lamp DL, and calculate Vla = | Vla1−Vla2 | The lamp voltage Vla is detected. Thereby, the function of the Vla detection circuit 52 in FIG. 1 is realized.

  The second pin of the microcomputer 55 outputs the target value of the lamp current Ila according to the characteristics shown in FIG. 5 set in advance according to the detected lamp voltage Vla, and the triangular wave generated by the high frequency oscillation circuit 56 and the comparator CP1. As a result, the drive signal for the switching element Q1 is generated as a PWM signal. 5 determines the lamp power Wla corresponding to the lamp voltage Vla by the memory table or the calculation function of the microcomputer 55, thereby realizing the function of the Wla calculation circuit 53 of FIG.

  Next, the drive signal for the switching element Q2 is generated by the high-frequency oscillation circuit 56 and the voltage obtained by dividing the voltage Vc2 of the capacitor C2 by resistance and comparing it with the target value V1 by the operational amplifier OP1 and the error amplified by the operational amplifier OP1. A PWM signal is generated by comparing the triangular wave with the comparator CP1, and this PWM signal is used as the other input of the AND gate for outputting the control signals of the switching elements Q1 and Q2.

  The voltage adjustment circuit 51 compares the voltage of the capacitor C2 with the target value V1, and an operational amplifier OP1 that amplifies the difference, and a MOS switch Qx and a buffer amplifier that detect the drive timing of the switching element Q2 from the low-frequency signal of FIG. A buffer amplifier OP3 is provided which combines OP2 and the outputs of the operational amplifiers OP1 and OP2 with a diode circuit and outputs the output of the operational amplifier OP1 as a reference voltage when the switching element Q2 is turned on.

  The output of the voltage adjustment circuit 51 and the output of the 2nd pin of the microcomputer 55 are synthesized by a diode circuit, the output of the 2nd pin of the microcomputer 55 is selected at the on timing of the switching element Q1, and at the on timing of the switching element Q2. The output of the voltage adjustment circuit 51 is selected and input to the comparator CP1.

  With such a configuration, the switching element Q2 performs a switching operation so that the capacitor C2 has a predetermined voltage, and the switching element Q1 performs a switching operation so as to have a set VI characteristic.

  The illustrated voltage adjustment circuit 51 is merely an example. In short, the voltage that is unbalanced when not lit by the capacitors C1 and C2 having different capacitance ratios is adjusted so as to be substantially equal during lighting. If possible, the specific circuit configuration is not limited.

(Embodiment 2)
A second embodiment of the present invention will be described with reference to FIG. Although the basic circuit configuration may be the same as that of the first embodiment, in the above-described first embodiment, when the lighting of the discharge lamp DL is determined, the voltage adjustment circuit 51 immediately starts to operate, and the voltages of the capacitors C1 and C2 Vc1 and Vc2 are switched so as to be equal immediately after lighting (see FIG. 2), whereas in the second embodiment, the voltage adjustment circuit 51 starts operation by adding a timer circuit or the like. The difference is that the timing to do is delayed.

  For example, the voltage adjustment circuit 51 in FIG. 3 receives the low-frequency signal in FIG. 4 and turns on the MOS switch Qx for a half cycle. If the output of the timer circuit is connected in parallel with the MOS switch Qx, The operation of the voltage adjustment circuit 51 can be prohibited by short-circuiting the output of the timer circuit during a non-lighting time and for a fixed time after starting.

  In a high pressure discharge lamp, the temperature in the arc tube is not stable immediately after starting, and thus arc discharge may become unstable. In such a case, switching the voltage of the capacitor is not preferable because it promotes instability and causes problems such as turning off.

  Therefore, in the second embodiment, as shown in FIG. 6, the voltage of the capacitor is set at the time when the arc discharge is sufficiently stabilized after the discharge lamp is turned on (for example, between about 10 seconds and 40 seconds after starting). Try to switch. By doing so, it is possible to prevent problems such as turning off due to voltage switching of the capacitors C1 and C2.

  Note that when the lamp is restarted, the timing for switching the capacitor voltage may be set earlier than at the initial start. This is because the temperature in the arc tube is higher at the restart than at the initial start.

  Further, the voltage of the capacitor may be gradually changed by gradually changing the target value V1 of the voltage adjustment of the capacitor C2 by the voltage adjusting circuit 51.

(Embodiment 3)
A third embodiment of the present invention will be described with reference to FIG. FIG. 7 shows the rise characteristic of the lamp voltage Vla and the change of the lamp current Ila when the metal halide lamp CDM-R70W (manufactured by Philips) is turned on.

  In the second embodiment described above, the capacitor voltage switching timing is determined by the timer circuit. However, in the third embodiment, the capacitor voltage switching timing is defined by lamp characteristics (lamp voltage or lamp current). Different.

  Although the basic circuit configuration may be the same as that of the first embodiment, in the above-described first embodiment, when the lighting of the discharge lamp DL is determined, the voltage adjustment circuit 51 immediately starts to operate, and the voltages of the capacitors C1 and C2 Vc1 and Vc2 are switched so as to be equal immediately after lighting, whereas in the third embodiment, when a detection value of the lamp voltage or lamp current is provided and the detection value becomes a predetermined value, The voltage adjustment circuit 51 is configured to start operation.

  For example, the capacitor voltage switching timing is set up to point A in FIG. Up to the point A, the region is mainly mercury luminescence, and after the point A is a region where metal iodide is the main luminescent material. The place where the change of the luminescent material is large is a region where the discharge of the lamp becomes unstable, and the capacitor voltage is switched before the unstable region (for example, the lamp voltage is between about 30 V and 60 V). Therefore, it is possible to more reliably prevent problems such as lamp extinction.

  In the third embodiment, since the characteristics of the lamp itself are detected, there is an advantage that the voltage switching timing of the capacitor is optimally determined according to the state of the lamp.

(Embodiment 4)
Embodiment 4 of the present invention will be described with reference to FIG. The discharge lamp of the present invention is an HID lamp, particularly a metal halide lamp. The metal halide lamp is filled with Hg as a buffer gas and a metal halide for obtaining a desired emission spectrum. In the case of CDM-35 and CDM-70, sodium (Na), thallium (Tl) or the like is enclosed as a metal halide. During a period when the lamp voltage is low immediately after starting the HID lamp, only Hg vapor is emitted. By passing the lamp current, the temperature in the arc tube gradually rises and the metal halide starts to emit light. FIG. 8 shows how the emission spectrum rises, and shows the characteristics of CDM-70 at the initial start. The horizontal axis indicates the elapsed time [seconds] after starting, and the vertical axis indicates the wavelength λ [nm] of the emission spectrum.

  In the fourth embodiment, when the light emission level of Tl or Na exceeds a predetermined value, the voltage adjustment circuit 51 is started to control the voltages of the capacitors C1 and C2 to be substantially equal. Regarding the circuit configuration, in the first embodiment, the spectrum detection unit includes a wavelength detection sensor for detecting 535 nm which is a T1 emission line or 589 nm which is an emission line of Na, and the detection output of the wavelength detection sensor has a predetermined value. When exceeded, the voltage adjustment circuit 51 is started to operate. By doing so, it is possible to more reliably detect the unstable time zone of the lamp discharge and to ensure the timing for switching the voltage of the capacitor.

  The determination that the detection output of the wavelength detection sensor exceeds the predetermined value may be made by comparing with a reference value using a comparator, or the detection output of the sensor may be monitored by an analog input port of the microcomputer. May be.

(Embodiment 5)
Embodiment 5 of the present invention will be described with reference to FIG. FIG. 9 shows the rising characteristics of the illuminance after starting the high-pressure discharge lamp. As a circuit configuration, in the first embodiment, as the illuminance detection means, an optical sensor is provided in the vicinity of the high-pressure discharge lamp, and when the detection output of the optical sensor exceeds a predetermined value, the voltage adjustment circuit 51 is started to operate. By doing so, the voltage of the capacitor can be switched after the arc is reliably stabilized.

  It is also possible to detect the stability of the arc by detecting the time change rate of illuminance. Therefore, it may be configured to detect that the arc has stabilized by detecting that the time change rate of the illuminance is within the fluctuation range during stable lighting, and to switch the voltage of the capacitor. For example, the detection output of the optical sensor is measured at regular time intervals using an analog input port of the microcomputer, and the operation of the voltage adjustment circuit 51 may be started when the fluctuation range of the detection value becomes less than a predetermined value.

(Embodiment 6)
FIG. 10 shows a configuration example of a lighting fixture using the high pressure discharge lamp lighting device according to any one of the first to fifth embodiments. FIG. 10 shows an example applied to a spotlight. In the figure, 21 is an electronic ballast storing a lighting device, 22 is a lamp body equipped with a high pressure discharge lamp, and 23 is a wiring.

It is a circuit diagram which shows the structure of Embodiment 1 of this invention. It is a wave form diagram which shows operation | movement of Embodiment 1 of this invention. It is a circuit diagram which shows the principal part structure of Embodiment 1 of this invention. FIG. 4 is a waveform diagram showing a polarity inversion operation of the circuit of FIG. 3. FIG. 4 is a characteristic diagram showing power control characteristics of the circuit of FIG. 3. It is a wave form diagram which shows operation | movement of Embodiment 2 of this invention. It is explanatory drawing of Embodiment 3 of this invention. It is explanatory drawing of Embodiment 4 of this invention. It is explanatory drawing of Embodiment 5 of this invention. It is a perspective view which shows the external appearance of the lighting fixture of Embodiment 6 of this invention. It is a circuit diagram of a conventional example. It is a wave form diagram which shows operation | movement of a prior art example.

Explanation of symbols

Q1, Q2 Switching element C1, C2 Capacitor L3 Inductor DL High pressure discharge lamp 5 Control circuit 51 Voltage adjustment circuit

Claims (7)

A series circuit of the first and second switching elements and a series circuit of the first and second capacitors are connected in parallel to the DC power supply, and a connection point between the first and second switching elements and the first and second A high pressure discharge lamp lighting device for lighting a high pressure discharge lamp connected via an inductor between connection points of capacitors, wherein the power supplied to the high pressure discharge lamp by switching the first and second switching elements Power control means for controlling the voltage, and voltage adjusting means for adjusting the voltage across the first and second capacitors to be different from each other when the high pressure discharge lamp is not lit and to be substantially equal when lit. High pressure discharge lamp lighting device. In claim 1, the voltage adjusting means adjusts the voltages at both ends of the first and second capacitors to be substantially equal when the high-pressure discharge lamp is lit, for a preset time after the high-pressure discharge lamp is started. A high pressure discharge lamp lighting device characterized by being after the elapse of time. 3. The high pressure discharge lamp lighting device according to claim 2, wherein the preset time is a time required for the discharge of the high pressure discharge lamp to be stabilized. 4. The method according to claim 1, further comprising means for detecting a lamp voltage or a lamp current, wherein the voltage adjusting means is based on the detected output of the lamp voltage or the lamp current after the high pressure discharge lamp is started. 2. A high pressure discharge lamp lighting device that switches from a non-lighting control that adjusts the voltages at both ends of the two capacitors so as to be different from each other to a control during lighting that is adjusted to be substantially equal. 4. The method according to claim 1, further comprising means for detecting an emission spectrum of the high-pressure discharge lamp, wherein the voltage adjusting means includes the first and second voltage adjusting means after the specific emission spectrum of the high-pressure discharge lamp becomes equal to or greater than a predetermined value. The high-pressure discharge lamp lighting device is characterized in that the control at the time of lighting is adjusted so as to be substantially equal to the control at the time of non-lighting, in which the voltages at both ends of the capacitor are adjusted to be different from each other. 4. The light source according to claim 1, further comprising means for detecting the illuminance of the high-pressure discharge lamp, and after the illuminance of the high-pressure discharge lamp exceeds a predetermined illuminance, or the time change rate of the detected illuminance is stable. After being within the time fluctuation range, the voltage adjusting means performs the control at the time of lighting that adjusts the voltages at both ends of the first and second capacitors so as to be substantially equal to the control at the time of non-lighting that is adjusted to be different from each other. A high pressure discharge lamp lighting device characterized by switching. A lighting fixture comprising the high pressure discharge lamp lighting device according to any one of claims 1 to 6.

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