JP4186789B2 - Electrodeless discharge lamp lighting device - Google Patents

Description

  The present invention relates to an electrodeless discharge lamp lighting device that supplies a high frequency output to an induction coil to light an electrodeless discharge lamp.

  Conventionally, an electrodeless discharge lamp lighting device for lighting an electrodeless discharge lamp has been provided. An electrodeless discharge lamp has a transparent spherical glass bulb or a glass bulb with an inner wall coated with a phosphor filled with a discharge gas composed of inert gas such as rare gas or metal vapor such as mercury vapor. The electrodeless discharge lamp lighting device generates a high-frequency electromagnetic field by causing a high-frequency current of several tens of kHz to several hundreds of MHz to flow through an induction coil disposed in the vicinity of the electrodeless discharge lamp. Is supplied with high frequency power to generate high frequency plasma current in a glass bulb of an electrodeless discharge lamp to generate ultraviolet rays or visible light (for example, see Patent Document 1).

  An example of this type of electrodeless discharge lamp lighting device is shown in FIG. This conventional apparatus is arranged in the vicinity of the electrodeless discharge lamp 6 by converting a direct current output of the direct current power supply E into a high frequency output by creating a desired direct current output from an alternating current output of a commercial alternating current power supply AC. And a power conversion circuit 9 to be supplied to the induction coil 5.

  The DC power supply E includes a rectifier circuit 10 that rectifies the AC output of the AC power supply AC and a conventionally known step-up chopper that includes an inductor L10, a diode D10, a switching element Q6, a smoothing capacitor C10, and a driving circuit 2 that drives the switching element Q6. It consists of a circuit.

  The power conversion circuit 9 includes a pair of switching elements Q3 and Q4 connected in series between the output terminals of the DC power supply E, and a resonance circuit including an inductor Ls and capacitors Cp and Cs is connected to the low-side switching element Q4. The above-described resonant circuit is configured by alternately switching a pair of switching elements Q3 and Q4 composed of a so-called half-bridge type inverter circuit and comprising field effect transistors by a drive signal of a rectangular wave pulse output from the drive circuit 11. A high frequency output is supplied to the induction coil 5 via

An example of a lighting fixture using the electrodeless discharge lamp 6 is shown in FIG. This luminaire includes a housing H that houses a DC power source E and a power conversion circuit 9, an induction coil 5, an electrodeless discharge lamp 6, and a reflector 20 that distributes light from the electrodeless discharge lamp 6.
JP 2003-45688 A (page 4-5, FIG. 1)

However, when the reflection plate 20 is made of a material having high conductivity such as metal, when a high frequency current is passed through the induction coil 5, an induction current is generated on the reflection plate 20 as indicated by an arrow A1, and the power conversion circuit 9 loss output power occur, lowering the startability of the electrodeless discharge lamp 6 for power shortage may occur.

  Then, if power is continuously supplied to the induction coil 5 without turning on the electrodeless discharge lamp 6, problems such as generation of radiation noise and wasteful power consumption occur.

The present invention has been made in view of the above reasons, and an object of the present invention is to provide an electrodeless discharge lamp lighting device capable of preventing the generation of radiation noise and power loss due to a decrease in startability of the electrodeless discharge lamp. There is.

According to the first aspect of the present invention, there is provided a DC power supply, a power conversion means for converting a DC output of the DC power supply into a high frequency output and supplying the induction coil disposed in the vicinity of the electrodeless discharge lamp, and an induction by controlling the power conversion means. predetermined and control means for adjusting the high-frequency output supplied to the coil, and a non-lighting detection means for detecting the unlighted electrodeless discharge lamp, the control means, a detected value detects a high-frequency output of the power conversion means a feedback control means for changing the high frequency output of the power conversion means so as to coincide with the reference value, when the non-lighting is detected by the non-lighting detection means after starting power conversion means after a predetermined detection wait time once stopping the power conversion means, repeating the operations such to start again the power conversion means in terms of varying the reference value so as to increase the frequency output of the power conversion means, non-lit Each time non-lighting is detected by the output means, the high frequency output of the power conversion means is gradually increased up to a predetermined upper limit output, and the power conversion means is changed when the high frequency output of the power conversion means becomes the upper limit output. It is characterized by being stopped .

According to this configuration, when the non-lighting of the electrodeless discharge lamp occurs, the high frequency output of the power conversion means is increased, so that the electrodeless discharge lamp can be restarted even in a situation where the startability is reduced. Since it is possible to prevent power from being continuously supplied to the induction coil while the electrode discharge lamp is extinguished, it is possible to prevent the startability of the electrodeless discharge lamp from being reduced and the generation of radiation noise and power loss due to non-lighting . In addition, the feedback control means can keep the high-frequency output of the power conversion means substantially constant, and the feedback control means and the control means can share circuit components to suppress an increase in the number of parts. Furthermore, even if the electrodeless discharge lamp does not light up, the high frequency output of the power conversion means is not increased beyond the upper limit output, so that unnecessary increase of the high frequency output is prevented and power consumption is suppressed, and the circuit components are excessive. A load can be prevented. In addition, if the electrodeless discharge lamp does not light even after restarting, the power conversion means is stopped, so it is possible to reliably reduce the startability of the electrodeless discharge lamp and the generation of radiation noise and power loss due to non-lighting. Can be prevented.

According to the present invention, when the non-lighting of the electrodeless discharge lamp occurs, the high frequency output of the power conversion means is increased and restarted, or the power conversion means is stopped, so the electrodeless discharge lamp is turned off. As a result, it is possible to prevent power from being continuously supplied to the induction coil, and it is possible to prevent generation of radiation noise and power loss due to a decrease in startability of the electrodeless discharge lamp. In addition, the feedback control means can keep the high-frequency output of the power conversion means substantially constant, and the feedback control means and the control means can share circuit components to suppress an increase in the number of parts. Furthermore, even if the electrodeless discharge lamp does not light up, the high frequency output of the power conversion means is not increased beyond the upper limit output, so that unnecessary increase of the high frequency output is prevented and power consumption is suppressed, and the circuit components are excessive. A load can be prevented. In addition, if the electrodeless discharge lamp does not light even after restarting, the power conversion means is stopped, so it is possible to reliably reduce the startability of the electrodeless discharge lamp and the generation of radiation noise and power loss due to non-lighting. Can be prevented.

  Hereinafter, the best mode for carrying out the present invention will be described.

( Reference example )
Before describing embodiments of the present invention, reference examples related to the present invention will be described. Since the basic configuration of this reference example is the same as that of the conventional example, common portions are denoted by the same reference numerals, description thereof is omitted, and only different portions are described.

In this reference example , as shown in FIG. 1, frequency control for inputting to the drive circuit 11 the detection resistor R1 connected to the source terminal of the switching element Q4 and the output voltage Vf corresponding to the voltage across the detection resistor R1. Circuit 12. The frequency control circuit 12 monitors the resonance current flowing in the power conversion circuit 9 with the voltage Vi across the detection resistor R1 (hereinafter referred to as “detection voltage Vi”), and when the detection voltage Vi falls below the threshold value. Detect unlit . That is, since the non-lighting times resonant current (high frequency current) is significantly reduced, the detection voltage Vi corresponding to the resonance current can unlighted is detected by comparing the threshold value corresponding to the current level during unlighted It is. The drive circuit 11 is composed of, for example, a voltage controlled oscillator (VCO), and outputs a drive signal having a lower frequency as the input voltage Vf from the frequency control circuit 12 is higher. When the input voltage Vf becomes 0, both the switching elements Q3 and Q4 are turned off. Thus, the power conversion circuit 9 is stopped. Other configurations are the same as the conventional example. Here, when the electrodeless discharge lamp 6 is started, the frequency of the drive signal of the drive circuit 11 is such that the electrodeless discharge lamp 6 of the resonance circuit including the induction coil 5, the inductor Ls, and the capacitors Cp and Cs is not lit. It is sufficiently higher than the resonance frequency in the (no load state). Therefore, by reducing the frequency of the drive signal of the drive circuit 11 and bringing it closer to the resonance frequency, the voltage Vx across the induction coil 5 can be increased and the high-frequency output of the power conversion circuit 9 can be increased.

The operation of this reference example will be described with reference to FIG. 2A to 2C are time charts in which the horizontal axis represents time t, and the vertical axis represents the voltage Vx across the induction coil 5, the detection voltage Vi, and the frequency f of the drive signal of the drive circuit 11, respectively.

After the AC power supply AC is turned on, the frequency control circuit 12 compares the detection voltage Vi with the starting threshold value Vth1, and the high frequency power supplied to the induction coil 5 when the detected voltage Vi becomes larger than the starting threshold value Vth1. It is detected that the size has reached a level necessary for starting the electrodeless discharge lamp 6 (time t = t1). After a predetermined detection waiting time T from this time t1, the frequency control circuit 12 compares the detection voltage Vi with the unlit threshold value Vth2. Then, when the detection voltage Vi is smaller than the non-lighting threshold value Vth2, non-lighting is detected, the power conversion circuit 9 is once stopped, and then the output voltage Vf to the drive circuit 11 is increased and then the power conversion circuit is again. By operating 9, the frequency f of the drive signal of the drive circuit 11 is lowered and the high frequency output of the power conversion circuit 9 is increased.

Then, the detection voltage Vi is compared again with the unlit threshold Vth2 after the detection waiting time T from the time t1 ′ when the voltage across the detection resistor R1 becomes larger than the starting threshold Vth1, and the detected voltage Vi is compared with the unlit threshold Vth2. If it is smaller, the output voltage Vf to the drive circuit 11 is further increased, and the same operation is repeated until no unlighting is detected (until t1 ″ + T in the figure).

Furthermore, when comparing the detection voltage Vi and unlighted threshold Vth2, the detection voltage Vi if Kere size than unlighted threshold Vth2, to maintain the output voltage Vf to the drive circuit 11.

That is, in this reference example , the frequency control circuit 12 and the detection resistor R1 are unlit detection means, and the frequency control circuit 12 and the drive circuit 11 are control means.

Here, the starting threshold value Vth1 is slightly lower than the voltage Vi across the detection resistor R1 when the magnitude of the high-frequency power supplied to the induction coil 5 reaches the level necessary for starting the electrodeless discharge lamp 6. Yes, the non-lighting threshold value Vth2 is lower than the voltage Vi between both ends of the detection resistor R1 when the electrodeless discharge lamp 6 is rated on and is lower than the voltage Vi between both ends of the detection resistor R1 when the electrodeless discharge lamp 6 is not lit. As a high value. The detection waiting time T is sufficiently longer than the starting time Δt. As shown in FIG. 3, the time required for restarting the electrodeless discharge lamp 6 can be shortened by making the detection waiting time T as close as possible to the starting time Δt.

According to the above configuration, because it increases the high frequency output of the power conversion circuit 9 when the unlighted electrodeless discharge lamp 6 is detected, that the startability can be startup the electrodeless discharge lamp 6 in a degraded state In addition, since it is possible to prevent power from being continuously supplied to the induction coil 5 while the electrodeless discharge lamp 6 is extinguished, radiation noise and wasteful power consumption associated with the non-lighting of the electrodeless discharge lamp 6 and a decrease in startability are possible. Can be prevented.

For example, by setting an upper limit value for the output voltage Vf to the drive circuit 11 of the frequency control circuit 12, the frequency f of the drive signal of the drive circuit 11 does not fall below the lower limit value fth as shown in FIG. An upper limit output may be set for the high frequency output of the power conversion circuit 9. According to this configuration, even if the electrodeless discharge lamp 6 is not lit, a high frequency output equal to or higher than the upper limit output is not output from the power conversion circuit 9, so that the power generated by supplying an excessive high frequency output to the induction coil 5. Waste and load on circuit components can be suppressed. Further, when the high frequency output of the power conversion circuit 9 reaches the upper limit output, that is, when the output voltage Vf from the frequency control circuit 12 to the drive circuit 11 reaches the upper limit value, the drive circuit 11 stops the power conversion circuit 9. You may make it make it. Alternatively, the frequency control circuit 12 counts the number of times that non-lighting is detected, and when the number reaches the predetermined number, the output voltage Vf to the drive circuit 11 is set to 0 and the power conversion circuit 9 is stopped. May be. According to these configurations, even if the electrodeless discharge lamp 6 is not turned on, power is not continuously supplied to the induction coil 5, so that generation of radiation noise and wasteful power consumption can be surely prevented. .

By the way, when the non- lighting of the electrodeless discharge lamp 6 occurs, the load as viewed from the AC power source AC decreases, so the current values of the DC power source E and the power conversion circuit 9 decrease. Therefore, even if the detection resistor R1 is connected to another position of the DC power supply E or the power conversion circuit 9, unlit detection based on the voltage Vi across the detection resistor R1 is possible. For example, the detection resistor R <b> 1 may be connected between the DC power supply E and the power conversion circuit 9. In this case, non-lighting is detected based on the output current of the DC power source E. According to this configuration, since it becomes difficult to be affected by noise from the switching elements Q3 and Q4, it is possible to further improve the accuracy of unlit detection.

Alternatively, the frequency control means 12 is connected to one end of the induction coil 5 as shown in FIG. 5, and when the voltage Vx across the induction coil 5 exceeds the start threshold Vth3 as shown in FIG. The frequency control circuit 12 may detect that the supplied high frequency power has reached a level necessary for starting the electrodeless discharge lamp 6. According to this configuration, noise is relatively difficult to mix into the voltage Vx across the induction coil 5, so that the detection accuracy can be further improved. In this case, the frequency control circuit 12 detects that the high-frequency power supplied to the induction coil 5 has reached a level necessary for starting the electrodeless discharge lamp 6, and then instead of timing the detection waiting time T, the induction coil 5 is monitored, and when a decrease in the voltage Vx across the induction coil 5 is detected, the detection voltage Vi may be compared with the unlit threshold Vth2.

In the above configuration, the power conversion circuit 9 is temporarily stopped when it is not lit , but it is not always necessary to stop the power conversion circuit 9, and the high-frequency output of the power conversion circuit 9 can be kept operating. May be increased. In this case, for example, as shown in FIG. 7, the detection voltage Vi is compared with the unlit detection threshold value Vth2 every detection waiting time T, and the high frequency output is increased stepwise each time unlit is detected. According to this configuration, the time required for restarting the electrodeless discharge lamp 6 can be further shortened. Further, as shown in FIG. 8, the detection voltage Vi and the non-lighting detection threshold value Vth2 are always compared, and until the non-lighting is detected, that is, until the electrodeless discharge lamp 6 is lit (t = t2). If the high frequency output is continuously increased, the time required for restarting the electrodeless discharge lamp 6 can be further shortened.

In the configuration described so far, when the non-lighting is detected, the high-frequency output of the power conversion circuit 9 is increased to attempt to restart the electrodeless discharge lamp 6. However, the non-lighting is detected once. In this case, the frequency control circuit 12 may cause the drive circuit 11 to stop the power conversion circuit 9 without attempting to restart the electrodeless discharge lamp 6. In this case, the frequency control circuit 12 and the drive circuit 11 serve as stopping means. According to this configuration, since power is not continuously supplied to the induction coil 5 with the electrodeless discharge lamp 6 turned off, generation of radiation noise due to a decrease in startability of the electrodeless discharge lamp 6 and wasteful power consumption. Can be surely prevented.

(Working-shaped state)
Since the basic configuration of this embodiment is the same as that of the reference example , common portions are denoted by the same reference numerals, description thereof is omitted, and only different portions are described.

In this embodiment, as shown in FIG. 9, instead of the frequency control circuit 12 of the reference example , the drive circuit 11 is controlled to keep the high frequency output of the power conversion circuit 9 constant, and the electrodeless discharge lamp 6 A feedback circuit 14 having a function of detecting non-lighting and controlling the drive circuit 11 to prevent generation of radiation noise or the like is provided. That is, in the present embodiment, the feedback circuit 14 and the drive circuit 11 are control means.

  More specifically, in the feedback circuit 14, the detection voltage Vi is input to the inverting input terminal via the resistor R3, the reference voltage Vref is input to the non-inverting input terminal via the diode D13, and the output terminal is driven. An operational amplifier OP connected to the circuit 11 is provided. A parallel circuit of a resistor R4 and a capacitor C5 is connected between the inverting input terminal and the output terminal of the operational amplifier OP, and an error amplifying circuit is configured by the resistors R3 and R4, the capacitor C5, and the operational amplifier OP. .

  When the detection voltage Vi is small, that is, when the high-frequency output of the power conversion circuit 9 is small, the difference between the input voltage to the inverting input terminal and the reference voltage Vref is large, and the output voltage Vf of the operational amplifier OP is large. Therefore, the frequency f of the drive signal of the drive circuit 11 is lowered, and the high frequency output of the power conversion circuit 9 is increased. When the detection voltage Vi is large, that is, when the high-frequency output of the power conversion circuit 9 is large, the high-frequency output of the power conversion circuit 9 is reduced by the reverse operation to the above. As described above, the feedback circuit 14 has a function of maintaining the high-frequency output of the power conversion circuit 9 at a substantially constant magnitude according to the reference voltage Vref. In addition, the magnitude | size of the reference voltage Vref is set to the magnitude | size corresponding to the magnitude | size of the high frequency output of the power converter circuit 9 of a grade required for carrying out the rated lighting of the electrodeless discharge lamp 6. FIG.

In addition to the reference voltage Vref, a capacitor C6 that is charged by the DC power source E through the resistor R5 and the diode D11 is connected to the non-inverting input terminal of the operational amplifier OP. Further, a series circuit of the diode D12 and the switching element Q7 and a resistor R6 for charging the capacitor C6 are connected in parallel to the series circuit of the capacitor C6 and the diode D11, respectively. Further, the feedback circuit 14 includes a reference voltage changing unit 13 that turns on and off the switching element Q7 in accordance with the detection voltage Vi. The reference voltage changing unit 13 turns on the switching element Q7 during a period in which the detection voltage Vi is higher than the unlighted threshold value Vth2, that is, a period in which unlit is not detected. During this time, the current flowing through the resistor R5 flows to the switching element Q7, and therefore the capacitor C6 is not charged, and the input voltage to the non-inverting input terminal of the operational amplifier OP becomes equal to the reference voltage Vref. Then, the reference voltage changing unit 13 turns off the switching element Q7 for a predetermined time from when the detection voltage Vi becomes lower than the unlighted threshold value Vth2, that is, when unlit is detected. During this time, the switching element Q7 is turned off and the capacitor C6 is charged, so that the input voltage to the non-inverting input terminal of the operational amplifier OP becomes larger than the reference voltage Vref. As a result, the output voltage Vf of the operational amplifier OP increases and the frequency f of the drive signal of the drive circuit 11 decreases, and therefore the high frequency output of the power conversion circuit 9 increases. Other configurations are the same as those in the reference example .

According to the above configuration, in addition to the same effects as in the reference example , the feedback circuit 14 can keep the high-frequency output of the power conversion circuit 9 substantially constant, and the feedback circuit 14 functions as the frequency control circuit 12 of the reference example. By also having, the increase in the number of parts can be suppressed.

It is a circuit diagram which shows the reference example of this invention. It is operation | movement explanatory drawing same as the above, (a) shows the time change of the both-ends voltage of an induction coil, (b) shows the time change of a detection voltage, (c) shows the time change of the frequency of the drive signal of a drive circuit. Show. It is operation | movement explanatory drawing which shows another form same as the above, (a) shows the time change of the both-ends voltage of an induction coil, (b) shows the time change of a detection voltage, (c) is the drive signal of a drive circuit. It shows the time change of frequency. It is operation | movement explanatory drawing which shows another form same as the above, (a) shows the time change of the both-ends voltage of an induction coil, (b) shows the time change of the frequency of the drive signal of a drive circuit. It is a circuit diagram which shows another form same as the above. It is operation | movement explanatory drawing which shows the same as the above, (a) shows the time change of the both-ends voltage of an induction coil, (b) shows the time change of a detection voltage, (c) is the time change of the frequency of the drive signal of a drive circuit. Indicates. It is operation | movement explanatory drawing which shows another form same as the above, (a) shows the time change of the both-ends voltage of an induction coil, (b) shows the time change of the frequency of the drive signal of a drive circuit. It is operation | movement explanatory drawing which shows another form same as the above, (a) shows the time change of the both-ends voltage of an induction coil, (b) shows the time change of the frequency of the drive signal of a drive circuit. Is a circuit diagram showing an embodiment of the present invention. It is a circuit diagram which shows a prior art example. It is a figure which shows an example of the illuminating device using an electrodeless discharge lamp.

Explanation of symbols

5 induction coil 6 electrodeless discharge lamp 9 power conversion circuit 11 drive circuit 12 frequency control circuit 14 feedback circuit E DC power supply

Claims (1)

DC power supply, power conversion means for converting the DC output of the DC power supply into high frequency output and supplying it to the induction coil disposed in the vicinity of the electrodeless discharge lamp, and high frequency output supplied to the induction coil by controlling the power conversion means And a non- lighting detection means for detecting non-lighting of the electrodeless discharge lamp. The control means detects the high-frequency output of the power conversion means and matches the detected value with a predetermined reference value. a feedback control means for changing the high frequency output of the power conversion means to temporarily stop the power conversion means when the unlighted is detected by the non-lighting detection means after starting power conversion means after a predetermined detection wait time Then, after changing the reference value so as to increase the high-frequency output of the power conversion means, the operation of starting the power conversion means again is repeated. Gradually with increasing the high frequency output of the power converter as a limit to a predetermined upper limit output each time the lamp is detected, halting the power conversion means when the high frequency output of the power conversion unit becomes the upper limit output An electrodeless discharge lamp lighting device .

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