JP2010044978A - High pressure discharge lamp lighting device, and illumination apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device for making a starting pulse voltage in non-load a proper value at a low cost. <P>SOLUTION: The high-pressure discharge lamp lighting device includes a power conversion circuit 1 which supplies a prescribed power to a high pressure discharge lamp La of a load using the output of DC power supply E as a power source, a polar inversion circuit 2 which converts the output of the power conversion circuit 1 into a rectangular wave AC and impresses on the high pressure discharge lamp La, a starting pulse generating circuit 3 which impresses a high voltage pulse voltage for starting in polar inversion of the rectangular wave AC in no load, and a control circuit 5 which controls each circuit. The control circuit 5 detects the output voltage VC1 of the power conversion circuit 1 in no load, and polarity inverts the polar inversion circuit 2 when the detected voltage is in a prescribed range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-pressure discharge lamp lighting device and a lighting fixture using the same.

  High-pressure discharge lamps have a compact shape and can obtain a high luminous flux with a high wattage, and are close to point light sources and easy to control light distribution. Therefore, they have recently been used as an alternative to incandescent lamps and halogen lamps. In general, a high-pressure discharge lamp requires a high-voltage pulse voltage of several kV to start, and a typical circuit configuration as a conventional example is shown in FIG. In the figure, E is a DC power source, 1 is a power conversion circuit, 2 is a polarity inversion circuit, 3 is a start pulse generation circuit, and 4 is a high voltage pulse transformer.

  The power conversion circuit 1 is a general step-down chopper circuit composed of a switching element Q1, a diode D1, an inductor L1, and a smoothing capacitor C1, and since its configuration and operation are well known, description thereof is omitted. The polarity inversion circuit 2 is composed of a full bridge circuit of switching elements Q2 to Q5, and applies a rectangular wave of several tens to several hundreds Hz to the starting pulse generation circuit 3 and the high pressure discharge lamp La. In the polarity inversion circuit 2, the switching elements Q2 and Q5 are on, the switching elements Q3 and Q4 are off, and the switching elements Q2 and Q5 are off and the switching elements Q3 and Q4 are on. It repeats alternately at Hz.

  The starting pulse generation circuit 3 includes a high-pressure pulse transformer 4 having a secondary winding N2 connected in series with the high-pressure discharge lamp La, a capacitor C2 for causing a pulse current to flow through the primary winding N1, and a charging resistance R And a voltage response element Q6 for discharging the capacitor C2. The pulse generation operation is well known. For example, when the switching elements Q2 and Q5 of the polarity inverting circuit 2 are on and the switching elements Q3 and Q4 are off, the primary winding of the switching element Q2 and the pulse transformer 4 from the capacitor C1. A charging current flows to the capacitor C2 via N1, the charging resistor R, the capacitor C2, and the switching element Q5, and the capacitor C2 is charged so that the voltage response element Q6 side becomes +. Thereafter, when the switching elements Q2 and Q5 of the polarity inverting circuit 2 are turned off and the switching elements Q3 and Q4 are turned on, a high voltage obtained by adding the voltage of the capacitor C2 and the voltage of the capacitor C1 is applied to the voltage response element Q6. When the breakover voltage of the element Q6 is exceeded, the charge of the capacitor C2 is abruptly discharged through the voltage response element Q6, and the steep discharge current flows to the primary winding N1 of the high voltage pulse transformer 4, so that the pulse voltage is increased. A high voltage pulse voltage generated and boosted by the pulse transformer 4 is generated in the secondary winding N2, and the high voltage discharge lamp La is broken down.

The discharge lamp lighting device as described above is disclosed in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 11-307295).
JP-A-11-307295

  In the above-described prior art, there is a correlation between the voltage value of the start pulse and the voltage VC1 of the capacitor C1, and in order for the start pulse voltage to be within a predetermined range, the voltage VC1 is in the range from the lower limit voltage VL to the upper limit voltage VH. It is necessary to output a start pulse when it is within.

  In general, a high-pressure discharge lamp has a starting pulse voltage of 3 to 5 kV. Recently, the number of cases in which the tube lamp circuit is extended to about 2 to 5 m is increasing, but in the case of the circuit configuration as described above, the power conversion circuit 1 is configured so that the starting pulse voltage falls within a predetermined range. Generally, the output voltage is controlled within a predetermined range. However, since high accuracy is required, there is a problem that the cost increases due to the use of volume resistors and the complexity of the control circuit. It was.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a high-pressure discharge lamp lighting device capable of setting a start pulse voltage at no load at an appropriate value at a low cost. There is.

  According to the present invention, in order to solve the above-described problem, as shown in FIG. 1, a power conversion circuit 1 that supplies predetermined power to a high-pressure discharge lamp La of a load using an output of a DC power source E as a power source, A polarity reversing circuit 2 that converts the output of the conversion circuit 1 into a rectangular wave alternating current and applies it to the high pressure discharge lamp La, and a high voltage pulse voltage for starting to the high pressure discharge lamp La when the polarity of the rectangular wave alternating current is reversed at no load. In the high pressure discharge lamp lighting device provided with the start pulse generating circuit 3 to be applied and the control circuit 5 for controlling each of the above circuits, the control circuit 5 detects the output voltage VC1 of the power conversion circuit 1 at no load, When the detected voltage is within a predetermined range, the polarity inversion circuit 2 is inverted in polarity.

  As shown in FIGS. 2 and 3, the start pulse generating circuit 3 according to the second aspect of the present invention provides the energy required for dielectric breakdown of at least the high-pressure discharge lamp La from the previous polarity reversal. The polarity is inverted after a time (period α) or more necessary for accumulating in the substrate has elapsed.

  In the invention of claim 3, in the invention of claim 1 or 2, as shown in FIGS. 4 and 5, the polarity inversion interval of the polarity inversion circuit 2 has a maximum value, and the maximum value (period β) is The polarity inversion interval is less than or equal to the pulse width that is thicker than the total time of the high-pressure pulse width per unit time required for starting the high-pressure discharge lamp La.

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, as shown in FIGS. 6 to 8, when the detected voltage VC1 of the power conversion circuit 1 exceeds a predetermined range, the power conversion circuit 1 A circuit (resistor R2) that consumes power is connected to the output unit to reduce the output voltage of the power conversion circuit 1.

  The invention of claim 5 is an illumination fixture comprising the high pressure discharge lamp lighting device according to any one of claims 1 to 4 (FIG. 9).

  According to the present invention, a high voltage pulse voltage within a predetermined range can be applied to a high pressure discharge lamp at no load with a simple circuit configuration, and the high pressure discharge lamp can be started reliably. In addition, since a high-voltage pulse voltage that is too high is not applied, there is no possibility of impairing the insulation of the lamp socket and the wiring.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
(Embodiment 1)
FIG. 1 is a circuit diagram of Embodiment 1 of the present invention. The DC power source E is, for example, a DC voltage obtained by rectifying and smoothing a commercial AC power source. The DC power supply E is generally set to the output voltage (several hundred volts) of the boost chopper circuit.

  The power conversion circuit 1 includes a general step-down chopper circuit, and steps down the DC voltage of the DC power source E to control the power supplied to the high-pressure discharge lamp La, which is a load, to an appropriate value.

  A circuit configuration of the power conversion circuit 1 will be described. The positive electrode of the DC power supply E is connected to the positive electrode of the capacitor C1 via the switching element Q1 and the inductor L1, and the negative electrode of the capacitor C1 is connected to the negative electrode of the DC power supply E. The negative electrode of the capacitor C1 is connected to the anode of a regenerative current conducting diode D1, and the cathode of the diode D1 is connected to the connection point of the switching element Q1 and the inductor L1.

  The circuit operation of the power conversion circuit 1 will be described. The switching element Q1 is turned on / off at a high frequency by a control signal from the control circuit 5. When the switching element Q1 is on, a current flows from the DC power source E via the switching element Q1, the inductor L1, and the capacitor C1. When Q1 is off, a regenerative current flows through inductor L1, capacitor C1, and diode D1. Thereby, the DC voltage obtained by stepping down the DC voltage of the DC power supply E is charged in the capacitor C1. By changing the on-duty (ratio of on-time occupying one cycle) of the switching element Q1 by the control circuit 5, the voltage VC1 obtained in the capacitor C1 can be variably controlled.

  The power conversion circuit 1 has a function as a ballast for supplying target power to the high-pressure discharge lamp La that is a load. In addition, the output voltage is variably controlled so that appropriate power is supplied to the high-pressure discharge lamp La from the start to the arc discharge transition period to the stable lighting period.

  A polarity inversion circuit 2 is connected to the output of the power conversion circuit 1. The polarity inversion circuit 2 is a full bridge circuit composed of switching elements Q2 to Q5, and a pair of switching elements Q2 and Q5 and a pair of switching elements Q3 and Q4 are alternately turned on at a low frequency by a control signal from the control circuit 5. Thus, the output power of the power conversion circuit 1 is converted into rectangular wave AC power and supplied to the high-pressure discharge lamp La.

  The high-pressure discharge lamp La that is a load is a high-intensity high-pressure discharge lamp (HID lamp) such as a metal halide lamp or a high-pressure mercury lamp.

  Since the tube voltage of the high-pressure discharge lamp La is greatly reduced immediately after starting, the control circuit 5 can determine that the high-pressure discharge lamp La has been turned on by detecting a decrease in the output voltage of the power conversion circuit 1. After the lighting of the high-pressure discharge lamp La is determined, the pulse width of the switching element Q1 of the power conversion circuit 1 is controlled to a value suitable for transition to arc discharge, or the switching elements Q2 to Q5 of the polarity inversion circuit 2 The polarity inversion timing can be switched to a cycle suitable for lighting.

  As described above, after starting the high-pressure discharge lamp La, the voltage of the capacitor C1 decreases and the charging voltage of the capacitor C2 also decreases, so that the voltage response element Q6 does not break over and the generation of the start pulse is stopped. To do.

  The difference between the present embodiment and the conventional example (FIG. 10) is that the control circuit 5 detects the charging voltage VC1 of the capacitor C1, and receives the detection result. In other words, the switching operation is controlled and the timing of polarity inversion of the switching elements Q2 to Q5 of the polarity inverting circuit 2 is controlled.

  The circuit operation of FIG. 1 will be described below. When there is no load, the power conversion circuit 1 steps down the voltage of the DC power source E to a voltage of about 300V and outputs the voltage. Here, no load means a state in which the discharge lamp La is not lit or disconnected.

  The polarity inversion circuit 2 receives the signal from the control circuit 5 and is in a state in which the switching elements Q2 and Q5 are on, the switching elements Q3 and Q4 are off, the switching elements Q2 and Q5 are off, and the switching elements Q3 and Q4 are on Are repeated alternately.

  First, when the switching elements Q2 and Q5 are turned on, current flows through the loop of the capacitor C1, the switching element Q2, the primary winding N1 of the pulse transformer T, the charging resistor R, the capacitor C2, and the switching element Q5, and the capacitor C2 is charged. When the time elapses, the battery is charged to substantially the same voltage as the voltage VC1 of the capacitor C1. In this state, when the polarity of the polarity inverting circuit 2 is reversed and the switching elements Q2 and Q5 are turned off and the switching elements Q3 and Q4 are turned on, the voltage response element Q6 has a voltage approximately twice the voltage VC1 of the capacitor C1 at both ends. Is applied and the voltage response element Q6 is turned on to exceed the breakover voltage of the voltage response element Q6. Then, the electric charge accumulated in the capacitor C2 suddenly flows to the primary winding N1 of the transformer 4 via the voltage response element Q6, thereby generating a pulse voltage in the primary winding N1, which is generated by the secondary winding N2. And a start pulse is applied to the discharge lamp La to start the discharge lamp La.

  Here, there is a correlation between the voltage value of the starting pulse and the voltage VC1 of the capacitor C1, and in order for the starting pulse voltage to fall within a predetermined range, the voltage VC1 is within the range from the lower limit voltage VL to the upper limit voltage VH. Sometimes it is necessary to output a starting pulse.

  In the present embodiment, the voltage VC1 of the capacitor C1 is detected by the control circuit 5 so that the discharge lamp applied voltage at no load is not too high while ensuring the startability of the discharge lamp, and the voltage VC1 is When the upper limit voltage VH is exceeded, the switching element Q1 is forcibly turned off, the charge accumulated in the capacitor C1 is discharged, and the voltage VC1 is lowered. When the voltage VC1 drops to the lower limit voltage VL, the switching element Q1 starts the switching operation again. At the time of no load, the switching element Q1 repeats the above operation.

  As a control means, for example, a control flow of the switching elements Q2 to Q5 when a microcomputer is used is shown in FIG.

  In the present embodiment, the polarity inversion circuit 2 is not inverted again even if VL <VC1 <VH only after a predetermined period α has elapsed since the polarity inversion circuit 2 has inverted the polarity. Even if VL <VC1 <VH immediately after polarity reversal, a certain period of time is required to generate a desired start pulse. This period is determined by the energy charged in the capacitor C2, and is specifically determined by the time constant depending on the resistance of the resistor R and the capacitor C2. Let this period be α.

  First, after the switching elements Q2 and Q5 are turned on and the switching elements Q3 and Q4 are turned off in (A), the elapsed time T is counted in (A-1). In (A-2), the elapsed time T is compared with the above-described period α. If the elapsed time T is less than α, the process returns to (A) and repeats until T> α. When the elapsed time T is greater than or equal to α, the voltage VC1 of the capacitor C1 is detected by the control circuit 5, and the microcomputer VC compares the voltage VC1 with the upper limit voltage VH in (B).

  If VC1> VH, it means that the voltage of the capacitor C1 is too high. Therefore, returning to (A), VC1 is detected again, and this is repeated until VC1 <VH. When VC1 <VH, the comparison with the lower limit voltage VL is performed next in (C). If VC1 <VL, the process returns to (A) and the above operation is repeated. This is repeated until VL <VC1 <VH. When VL <VC1 <VH, the counter of the elapsed time T is reset, and the polarity inversion circuit 2 is inverted in (D).

  When the polarity is reversed, the elapsed time T is similarly counted until T> α in (D-1), and the voltage VC1 of the capacitor C1 is detected by the control circuit 5 after T> α in (D-2). In step (E), the microcomputer compares the voltage VC1 with the upper limit voltage VH. If VC1> VH, it means that the voltage of the capacitor C1 is too high. Therefore, returning to (D), VC1 is detected again, and this is repeated until VC1 <VH. When VC1 <VH, the comparison with the lower limit voltage VL is performed next in (F). If VC1 <VL, the process returns to (D) and the above operation is repeated. This is repeated until VL <VC1 <VH. When VL <VC1 <VH, the counter T is reset, and the process returns to (A) to invert the polarity of the polarity inversion circuit 2.

  By repeating such an operation, the polarity inversion circuit 2 inverts the polarity only after a predetermined period α has elapsed from the polarity inversion and when the voltage VC1 of the capacitor C1 is within the predetermined range, and a start pulse is generated. Therefore, the voltage value of the start pulse can be kept in a desired range. Further, since the start pulse is generated only once for each polarity inversion, the stress applied to the switching elements Q2 to Q5 can be reduced.

(Modification 1)
In the first embodiment, the voltage VC1 of the capacitor C1 is detected by the control circuit 5 so that the discharge lamp applied voltage at no load does not become too high. When the voltage VC1 exceeds the upper limit voltage VH, the switching element Q1 is forcibly turned off, and the voltage VC1 is lowered by discharging the electric charge accumulated in the capacitor C1, and when the voltage VC1 drops to the lower limit voltage VL, the switching element Q1 starts the switching operation again. However, as a modification, in order to ensure the startability of the discharge lamp, the switching element Q1 of the step-down chopper circuit performs a constant switching operation at no load regardless of the voltage VC1 of the capacitor C1. It may be configured.

(Modification 2)
In the first embodiment, the polarity inversion circuit 2 is not inverted again even if VL <VC1 <VH unless a predetermined period α has elapsed since the polarity inversion circuit 2 has inverted the polarity. A case where the polarity inversion circuit 2 is inverted without waiting for the elapse of the predetermined period α will be described. Before time T1, VC1> VH, switching element Q1 is off, switching elements Q2 and Q5 are on, and switching elements Q3 and Q4 are off. Since VC1 <VH at time T1, switching element Q1 starts a switching operation. At the same time, switching elements Q2 and Q5 are turned off, switching elements Q3 and Q4 are turned on, and a starting pulse is generated. At this time, if the energy supplied to the capacitor C1 is smaller than the energy required for the start pulse, the voltage VC1 of the capacitor C1 decreases, but since VL <VC1 <VH, the polarity inversion circuit 2 repeats the polarity inversion. In this case, since sufficient energy is not stored in the capacitor C2 of the start pulse generation circuit 3, the voltage of the start pulse after the second time is reduced and the energy consumption is also reduced. Therefore, after the first start pulse is generated, the voltage VC1 is Rise gradually. Thereafter, when VC1> VH, the switching element Q1 stops the switching operation, and at the same time, the polarity inversion operation of the polarity inversion circuit 2 also stops. Since the switching element Q1 stops the switching operation, the voltage VC1 gradually decreases and the above operation is repeated when VC1 <VH.

(Embodiment 2)
The flowchart of the control of this embodiment and the time chart of each part waveform are shown in FIGS. 4 and 5, respectively. Since the circuit configuration is the same as that of the first embodiment, the description is omitted. In the first embodiment, the polarity reversing circuit 2 is not reversed again even if VL <VC1 <VH only after a predetermined period α has passed since the polarity reversing circuit 2 reversed the polarity. The feature is that the polarity is forcibly reversed when a period β of α <β elapses from the previous polarity reversal.

  In the first embodiment, a start pulse is applied to the discharge lamp every time the polarity is reversed, and the electrode is heated during glow discharge. However, the longer the polarity reversal interval, the colder the heated electrode becomes, and the next polarity There is a problem that it becomes difficult to discharge during reversal. The present embodiment has been made to avoid such a phenomenon, and a specific configuration will be described below, but differences from the first embodiment will be described for the sake of simplicity.

  The difference from the first embodiment in the flowchart is the addition of the branches (A-3) and (D-3). After confirming that T> α in (A-2), it is determined whether or not T <β in (A-3). If T> β, the process branches immediately after (C), resets the elapsed time T, and forcibly reverses the polarity. Similarly, (D-3) branches immediately after (F) when T> β and forcibly reverses the polarity.

  The predetermined period β is preferably set to be equal to or less than the polarity inversion interval so that the pulse width is thicker than the total time of the high-pressure pulse width per unit time required for starting the high-pressure discharge lamp.

  Further, the time chart is as shown in FIG. 5, and VC1> VH at the time when the predetermined period β has elapsed, but the polarity inversion circuit 2 forcibly inverts the polarity. By configuring in this way, the fluctuation range of the starting pulse voltage is widened as compared with the first embodiment, but deterioration of starting performance can be prevented.

(Embodiment 3)
FIG. 6 is a circuit diagram of Embodiment 3 of the present invention. The flowchart of the control of this embodiment and the time chart of each part waveform are shown in FIGS. 7 and 8, respectively. The difference from the first and second embodiments is that a series circuit of a resistive load R2 and a switch element Q7 is connected in parallel with the capacitor C1 in this embodiment. A specific configuration will be described below.

  In the first and second embodiments, when VC1> VH, the switching operation of the switching element Q1 is stopped and the polarity inversion circuit 2 stands by without inverting the polarity until VC1 <VH. In this case, since the electric charge of the capacitor C1 is discharged only by natural discharge, it takes about several ms to satisfy VC1 <VH. Since the electrode is cooled during this period, the second embodiment adopts a method of forcibly inverting the polarity of the polarity inverting circuit 2 after a predetermined period β has elapsed. However, in this case, the voltage value of the start pulse may not fall within the predetermined range.

  Therefore, in the present embodiment, when VC1> VH, when branching at (B) or (E) in the flowchart of FIG. 7, for example, a pulse signal of several k to several tens kHz is output from the control circuit 5, and the switching element Q7 is turned on intermittently. When the switching element Q7 is turned on, the resistance load R2 is connected in parallel with the capacitor C1, so that the decrease in the voltage VC1 can be accelerated. This is repeated until VC1 <VH, and the process proceeds to the next process.

  Referring to the time chart of FIG. 8, the polarity inversion circuit 2 first reverses the polarity at time T1, and the voltage VC1 decreases at the same time as the start pulse is generated. Thereafter, after time T2, switching element Q1 starts switching operation, voltage VC1 rises, VC1> VH, and then switching element Q1 stops switching operation at time T3. At the same time, the switching element Q7 is repeatedly turned on and off at, for example, several k to several tens of kHz, and the voltage VC1 decreases again. At time T4, VC1 <VH. At this time, since T <α, the polarity inversion circuit 2 has not yet reversed in polarity, and the switching element Q1 starts the switching operation again. At the same time, the switching element Q7 stops the switching operation. To do. Since VC1> VH immediately after that, the switching element Q1 stops the switching operation, the switching element Q7 starts the switching operation, and the voltage VC1 decreases again. At time T5, VC1 <VH. At this time, since T> α, the polarity inversion circuit 2 inverts the polarity and generates a starting pulse.

  With this configuration, the time until VC1 <VH can be shortened, and the time until polarity reversal can be shortened. Thus, as in the second embodiment, the startability is prevented from being deteriorated, and the start pulse is reliably transmitted. The voltage value can fall within a predetermined range.

(Embodiment 4)
FIG. 9 shows a structural example of a lighting fixture using the high pressure discharge lamp lighting device of the present invention. (A), (b) is an example using an HID lamp as a spotlight, and (c) is an example using an HID lamp as a downlight. In the figure, La is a high pressure discharge lamp, 81 is a high pressure discharge lamp. A mounted lamp body, 82 is a wiring, and 83 is a ballast storing a circuit of a lighting device. A lighting system may be constructed by combining a plurality of these lighting fixtures. By using the high pressure discharge lamp lighting device according to any one of the first to third embodiments as these lighting devices, the peak value of the starting pulse can be optimized.

It is a circuit diagram of Embodiment 1 of the present invention. It is a flowchart which shows operation | movement of Embodiment 1 of this invention. It is an operation | movement waveform diagram of Embodiment 1 of this invention. It is a flowchart which shows operation | movement of Embodiment 2 of this invention. It is an operation | movement waveform diagram of Embodiment 2 of this invention. It is a circuit diagram of Embodiment 3 of the present invention. It is a flowchart which shows operation | movement of Embodiment 3 of this invention. It is an operation | movement waveform diagram of Embodiment 3 of this invention. It is a perspective view which shows the external appearance of the lighting fixture of Embodiment 4 of this invention. It is a circuit diagram of a conventional example.

Explanation of symbols

E DC power source 1 Power conversion circuit 2 Polarity inversion circuit 3 Start pulse generation circuit 5 Control circuit La High pressure discharge lamp

Claims (5)

A power conversion circuit that supplies predetermined power to a high-pressure discharge lamp of a load using an output of a DC power supply as a power supply;
A polarity inversion circuit that converts the output of the power conversion circuit into a rectangular wave alternating current and applies it to the high-pressure discharge lamp;
A start pulse generating circuit for applying a start high voltage pulse voltage to the high pressure discharge lamp at the time of no load when the polarity of the rectangular wave AC is reversed;
In the high pressure discharge lamp lighting device provided with a control circuit for controlling the above circuits,
The control circuit detects the output voltage of the power conversion circuit when there is no load, and reverses the polarity of the polarity inversion circuit when the detected voltage is within a predetermined range. 2. The polarity inversion is performed after at least the time necessary for accumulating at least the energy required for dielectric breakdown of the high-pressure discharge lamp in the starting pulse generation circuit from the previous polarity inversion. High pressure discharge lamp lighting device. The polarity inversion interval of the polarity inversion circuit has a maximum value, and the maximum value is such that the pulse width is larger than the total time of the high-pressure pulse width per unit time required for starting the high-pressure discharge lamp. The high-pressure discharge lamp lighting device according to claim 1, wherein the high-pressure discharge lamp lighting device is less than or equal to the distance between the two. The output voltage of the power conversion circuit is lowered by connecting a circuit that consumes power to the output unit of the power conversion circuit when the detection voltage of the power conversion circuit exceeds a predetermined range. The high pressure discharge lamp lighting device according to any one of? A lighting fixture comprising the high-pressure discharge lamp lighting device according to claim 1.

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