JP4089217B2 - Discharge lamp lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lighting device that starts a discharge lamp such as a fluorescent lamp, a low-pressure sodium lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal halide lamp, a ceramic metal halide lamp, and a high-pressure sodium lamp and then continuously lights the discharge lamp. .
[0002]
[Prior art]
In order to continue lighting after starting the discharge lamp, in the past, AC constant wave power as shown in FIG. 9A is generated by inverting DC constant power of an arbitrary voltage value at a predetermined cycle. In general, the AC rectangular wave power is supplied to the discharge lamp.
[0003]
This AC rectangular wave power has the advantage of easy waveform control and less light fluctuations within a half cycle. However, according to the inventors' experiment, depending on the type and characteristics of the lamp, the AC rectangular wave may not always be It turns out that it is not an optimal power waveform.
[0004]
For example, when AC square wave power is supplied to a discharge lamp and turned on, a large current fluctuation occurs at the time of reversing positive and negative, so a high voltage is generated even if the stray inductance is small, and the lamp flickers. In an internal starting type lamp having a built-in starter, the capacitor of the starter may be destroyed.
[0005]
In order to prevent this, if AC trapezoidal wave power as shown in FIG. 9B is supplied, the current gradually changes at the time of positive / negative reversal, so that the large voltage fluctuation as described above does not occur.
[0006]
Further, as shown in FIGS. 9C and 9D, a pulse waveform that increases the power value is added immediately before the inversion of the AC rectangular wave power, or gradually from the rise of the AC rectangular wave power to just before the fall. If the sawtooth waveform is used to increase the power value, the hot spots on the electrodes are strongly generated, so that the discharge between the electrodes is stabilized and not only has the effect of preventing flicker, but also an ultra high pressure mercury lamp. When the lamp is supplied and lit, there is an advantage that the metal life generated on the electrode is removed and the lamp life is extended.
[0007]
In particular, in the waveform as shown in FIG. 9 (d), since the power value gradually changes, the brightness of the screen does not partially change even when used in a liquid crystal projector. There is an advantage that can be obtained.
[0008]
[Problems to be solved by the invention]
However, in order to generate an arbitrary power waveform in this way, a function generator that costs one hundred thousand yen is required, and the size is as small as 50 cm × 30 cm × 10 cm. Incorporating this into the lighting device for each discharge lamp is difficult in terms of cost and space, and is not practical at all.
[0009]
Therefore, the present invention generates a lamp lighting AC power having an arbitrary waveform according to the characteristics of the discharge lamp with a very simple configuration, and is small and low cost, and applies this to the discharge lamp so that it can be continuously lit. This is a technical issue.
[0010]
[Means for Solving the Problems]
In order to solve this problem, the invention of claim 1 is a chopper circuit that converts a DC constant voltage output from a power supply circuit into DC rectangular wave power by turning on and off the switching element, and a smoothing that smoothes the DC rectangular wave power. A discharge lamp lighting device comprising: a lamp power adjustment circuit comprising a circuit; and a polarity reversing circuit that inverts the adjusted DC power output from the lamp power adjustment circuit at an arbitrary timing to generate AC power for lamp lighting. And
A power waveform setting means capable of preliminarily setting an arbitrary target AC power waveform to be applied to the discharge lamp,
It is set based on the instantaneous power value in the minute interval of the adjusted DC power output from the lamp power adjustment circuit and the target instantaneous power value of the target DC power obtained by rectifying the waveform of the target AC power in the minute interval corresponding to this. Lamp power control means for turning on and off the switching element of the chopper circuit with a power control pulse signal having a duty ratio of
A timing control means for outputting to the polarity inversion circuit a timing control signal for inverting the regulated DC power output from the lamp power adjustment circuit in synchronization with the target AC power;
The lamp power control means determines the duty ratio of the power control pulse signal for turning on and off the switching element, and the difference between the instantaneous power value of the adjusted DC power output from the smoothing circuit and the target instantaneous power value of the target DC waveform The duty ratio correcting means for performing feedback control based on the above is provided.
[0011]
According to the first aspect of the present invention, the switching element of the chopper circuit is turned on / off according to the duty ratio of the power control pulse signal by the power control pulse signal output from the lamp power control means.
Since this duty ratio is set based on the target DC power obtained by rectifying the target AC power, the DC constant voltage output from the power supply circuit is PWM-controlled by the chopper circuit and converted to DC rectangular wave power, which is smoothed By smoothing with the circuit, adjusted DC power having a waveform equal to the target DC power obtained by rectifying the target AC power can be obtained.
Therefore, if the obtained adjusted DC power is inverted by the polarity inversion circuit in synchronization with the target AC power, lamp lighting AC power having a waveform equal to the target AC power can be obtained.
[0012]
According to another aspect of the present invention, the switching power is applied to the lamp power control unit based on the difference between the instantaneous power value of the adjusted DC power output from the smoothing circuit and the instantaneous power value of the target DC power obtained by rectifying the target AC power. Control pulse generating means for feedback-controlling the duty ratio of the power control pulse signal for turning on / off.
[0013]
Therefore, the duty ratio of the power control pulse signal is feedback controlled based on the difference between the instantaneous power value of the adjusted DC power output from the smoothing circuit and the instantaneous power value of the target DC waveform obtained by rectifying the target AC power. Therefore, smoothing the PWM-controlled DC rectangular wave power provides an adjusted DC power that exactly matches the target DC power. Further, the DC power is accurately synchronized with the target AC power by inverting it in synchronization with the target AC power. AC power for lamp lighting having a waveform that matches the above is obtained.
[0014]
In addition, if a memory chip that records the target AC power to be applied to the discharge lamp is used as the waveform setting means as in the invention of claim 2, the target AC power can be easily set and changed by replacing the memory chip. Can be done.
[0015]
Similarly, if the memory for recording the waveform of the target AC power supplied from the external computer is used as the waveform setting means as in the invention of claim 3 , the target AC power can be easily set and changed by a simple operation. be able to.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
1 is a block diagram showing a discharge lamp lighting device according to the present invention, FIG. 2 is a circuit diagram showing a lamp power adjustment circuit, FIG. 3 is a circuit diagram showing a polarity inversion circuit, and FIG. 4 is each power waveform and each control pulse. FIG. 5 to FIG. 7 are flowcharts showing processing procedures, and FIG. 8 is a waveform diagram for explaining duty ratio correction processing.
[0017]
The discharge lamp lighting device 1 of the present example includes a lighting circuit E that lights the discharge lamp L, and a control unit that controls the lighting circuit E to generate lamp lighting AC power that matches a preset target AC power. C.
[0018]
The lighting circuit E includes a power supply circuit 2 that outputs a DC constant voltage, a lamp power adjustment circuit 3 that steps down the DC constant voltage to obtain adjusted DC power having a desired waveform, and an adjustment output from the lamp power adjustment circuit 3 A polarity inversion circuit 4 that inverts DC power at an arbitrary timing to generate AC power for lamp lighting, and a high-voltage starting voltage of several KV to several tens KV is applied when the starting switch of the discharge lamp L is turned on. A starting circuit 5 is provided.
[0019]
The power supply circuit 2 includes a rectifier circuit 7 that rectifies the sine AC voltage VS ₁ supplied from the AC power supply 6, and a power factor improvement circuit 8 that converts the rectified pulsating voltage VS ₂ into a DC constant voltage VS ₃ . .
[0020]
The lamp power adjustment circuit 3 is a front-stage chopper circuit that converts a DC constant voltage VS ₃ output from the power supply circuit 2 into a DC rectangular wave power WS ₄ by turning on and off an FET (field effect transistor) 9 serving as a switching element. 10 and a subsequent smoothing circuit 11 for smoothing the DC rectangular wave power WS ₄ and outputting the desired adjusted DC power WS ₅ .
[0021]
Specifically, the FET 9 disposed in the chopper circuit 10 is turned on / off by the power control pulse signal PW supplied from the PWM control circuit 22 of the control unit C, which will be described later, via the driver 9a, so that the target AC power WA ₀ is obtained. By outputting the DC rectangular wave power WS ₄ having a corresponding duty ratio and passing through the smoothing circuit 11, the adjusted DC power WS ₅ equal to the target DC power WD ₀ obtained by rectifying the target AC power WA ₀ is obtained.
[0022]
The polarity inversion circuit 4 is formed in a full-bridge type including four FETs (field effect transistors) 12A to 12D serving as switching elements, and the adjustment DC power WS ₅ applied to the input terminal 4in is supplied to the lamp lighting AC. It is converted into electric power WS ₆ to the output terminal 4out.
[0023]
Thus, the polarity control pulse signal supplied from the control unit C to be described later (timing control signal) P _A By to P _D, two FET12A and 12B positioned diagonally, and 12C and 12D as respective pairs, it turned on at a predetermined timing for each pair - has to switch off.
[0024]
Each FET12A~12D the respective polarity control pulse signal _{P A} ~ P _D The polarity control pulse signals P _{A to} P _D are output according to the timing when each FET 12A to 12D is turned on / off.
[0025]
The control unit C includes a single-chip microcomputer 21 and the like, and sensors 14a and 14b for detecting the voltage and current of the adjusted DC power WS ₅ output from the lamp power adjusting circuit 3 are A / D on the input side. The FETs 9 of the chopper circuit 10 are connected to the output side via the PWM control circuit 22 and the driver 9a, and the FET 12A of the polarity inversion circuit 4 is connected to the output side via the drivers 12a to 12d. ~ 12D are connected.
[0026]
Further, the control unit C is provided with a memory 23 serving as power waveform setting means for presetting the waveform of the target AC power WA ₀ to be applied to the discharge lamp L, and the power control pulse signal PW is supplied to the chopper circuit 10. The lamp power control means 24 for making the adjusted DC power WS ₅ coincide with the target DC power WD ₀ by outputting and the adjusted DC power WS ₅ output from the lamp power adjusting circuit 3 are synchronized with the target AC power WA _0. the polarity control pulse signal P _a to P _D to invert Te and a timing control unit 25 to be output to the polarity inversion circuit 4.
[0027]
The memory 23 can adopt any type. For example, a memory chip that records a waveform of a target AC power to be applied to the discharge lamp L is attached to and detached from the control unit C via a connector (not shown). A type or a type that can rewrite, set, or install the waveform of the target AC power from an external computer connected to the control unit C by communication means may be used.
[0028]
When a waveform signal WA having a waveform profile equivalent to the target AC power WA ₀ is stored in the memory 23, a waveform signal WD obtained by rectifying one cycle is registered, and when a preset power coefficient K is applied thereto, A waveform of the target DC power WD ₀ equal to the power value obtained by rectifying the target AC power WA ₀ is obtained.
[0029]
The target DC power WD ₀ is equally divided into n, and a time corresponding to 1 / n period is set as m times (about 1 ≦ m ≦ 1000) of the pulse period PC of the power control pulse signal PW, and the index The duty ratio of each power control pulse signal PWi according to the target instantaneous power Mi according to the waveform height of the target DC power WD ₀ with i = 1 to n and the DC constant voltage VS ₃ output from the power supply circuit 2 DTi is set.
[0030]
5 to 7 are flowcharts showing the processing procedure of the lamp power control means 24.
First, when the discharge lamp L is started, the program shown in FIG. 5 starts to be executed. First, at step STP1, the index i = 1 and the total electric energy TW = 0, the process proceeds to step STP2, and the time of the timer that measures the pulse period is measured. Set T = 0.
[0031]
In step STP3, the duty ratio DTi and the pulse period PC are read, in step STP4, the pulse width PLi = DTi × PC of each pulse PWi is calculated, and in step STP5, the pulse of the pulse width PLi that becomes the power control pulse signal PW is calculated. The PWM control circuit 22 of the control unit C is set so as to output.
[0032]
Next, the system waits for the time T measured by the timer in step STP6 to elapse m times the pulse period PC, and executes the duty ratio correction program (see FIG. 6) in step STP7. Furthermore, the process goes to step STP8 determines whether the process of one cycle of the target AC power WA ₀ is finished.
[0033]
This determination is made by determining whether i = n.
If it is determined that the process has not been completed, the index i = i + 1 is rewritten in step STP9, the process returns to step STP2, and the process of outputting the next power control pulse signal is continued.
If it is determined that the process has been completed, the power coefficient correction program (see FIG. 7) in step STP10 is executed, and then the process returns to step STP1.
[0034]
FIG. 6 shows a specific processing procedure of the duty ratio correction program in step STP7. Every time when the power control pulse signal PW is output by m pulses and the time T has elapsed by m times the pulse period PC, FIG. The feedback control is performed by correcting the duty ratio so that the adjusted DC power WS ₅ output from the lamp power adjusting circuit 3 becomes equal to the target DC power.
[0035]
Here, the voltage Vi and the current Ii detected by the sensors 14a and 14b in step STP11 are taken in, and the waveform shape value Fi and the power coefficient K are read in step STP12. Based on these values, the adjusted DC power is adjusted in step STP13. WS ₅ instantaneous power Wi = Vi × Ii, target instantaneous power Mi = K × Fi, and total power amount TW = TW + Wi are calculated.
At this time, DC constant voltage VS ₃ , adjusted DC power WS ₅ and its instantaneous power Wi, target DC power WD ₀ and its target instantaneous power Mi, waveform signal WD and its waveform shape value Fi, voltage Vi, current Ii, power FIG. 8 shows the relationship between the coefficient K, the pulse width PLi of the power control pulse signal PW, the pulse period PC, and the duty ratio DTi.
[0036]
Next, in step STP14, a difference dW = Wi−Mi between the instantaneous power Wi and the target instantaneous power Mi is calculated.
Here, when dW <0, the instantaneous power Wi is smaller than the target instantaneous power Mi, so that the process proceeds to step STP15 and rewrites by increasing the duty ratio DTi according to the value of dW.
Further, when dW> 0, the instantaneous power Wi is larger than the target instantaneous power Mi. Therefore, the process proceeds to step STP16 and is rewritten by decreasing the duty ratio DTi according to the value of dW.
Further, when dW = 0, since the instantaneous power Wi is equal to the target instantaneous power Mi, the process is terminated without rewriting the duty ratio DTi.
[0037]
Figure 7 shows a concrete processing procedure of the power factor correction program of the step STP10, whenever the processing of one cycle of the target AC power WA ₀ is completed, the total power TW of one period This is for performing feedback control by correcting the power coefficient K so as to be equal to a preset set power amount SW.
[0038]
Here, the total power amount TW calculated in the previous step STP13 and the preset set power amount SW are read in step STP21, and the difference dT = TW−SW is calculated in step STP22.
When dT <0, the total power amount TW is smaller than the set power amount SW, so that the process proceeds to step STP23 where the power coefficient K is increased according to the value of dT and rewritten.
When dT> 0, the total power amount TW is larger than the set power amount SW. Therefore, the process proceeds to step STP24 where the power coefficient K is decreased according to the value of dT and rewritten.
Further, when dT = 0, the total power amount TW is equal to the set power amount SW, and thus the process is terminated without rewriting the power coefficient K.
[0039]
The above is one configuration example of the present invention, and the operation thereof will be described next.
First, when the waveform signal WA of the target AC power WA ₀ that gradually increases from rising to falling is stored in the memory 23 of the control unit C, the waveform signal WD obtained by rectifying the one cycle is registered. Is multiplied by the power coefficient K, a waveform of the target DC power WD ₀ equal to the power value obtained by rectifying the target AC power WA ₀ is obtained.
[0040]
The target DC power WD ₀ is equally divided into n, and a time corresponding to 1 / n period is set as m times (about 1 ≦ m ≦ 1000) of the pulse period PC of the power control pulse signal PW, and the index The duty ratio DTi of each control pulse signal PWi is set according to the target instantaneous power Mi corresponding to each waveform of i = 1 to n and the DC constant voltage VS ₃ output from the power supply circuit 2.
[0041]
Here, when the discharge lamp L is started, the sine wave AC voltage VS ₁ output from the AC power source 6 is rectified by the rectifier circuit 7 to become a pulsating voltage VS ₂ , and is converted to the DC constant voltage VS ₃ by the power factor correction circuit 8. It is converted and supplied to the chopper circuit 10.
On the other hand, the chopper circuit 10 receives the power control pulse signal PW from the control unit C, and the FET 9 is on / off controlled.
Duty ratio DTi of the power control pulse signal PW is set so as to gradually pulse width PLi toward the rising of the target AC power WA ₀ to falling widens, conduction time of FET9 according to the duty ratio DTi Is turned on and off to gradually increase.
[0042]
Therefore, the DC rectangular wave power WS ₄ output from the chopper circuit 10 gradually increases in pulse width from the rising edge to the falling edge of the target AC power WA ₀ , and this is input to the smoothing circuit 11. The smoothed adjusted DC power WS ₅ has a waveform equal to the target DC power WD ₀ and is input to the polarity inversion circuit 4.
[0043]
The polarity inversion circuit 4, polarity control pulse signal P _A By to P _D, since FET12A~12D is turned on and off in synchronization with the inversion timing of the target AC power WA _0, the regulated DC power WS ₅ to the lamp lighting AC power WS ₆ equal waveform to the target AC power WA ₀ conversion Is done.
[0044]
In this manner, since the lamp lighting AC power WS ₆ having a waveform equal to the preset arbitrary target AC power WA ₀ can be generated, the optimum target AC power WA according to the characteristics of the discharge lamp L can be generated. By setting ₀ waveform, it is possible to light up under optimum conditions.
[0045]
Incidentally, each time the individual pulses of the power control pulse signal PW is the m output to the chopper circuit 10 from the control station C, a voltage and current of the regulated DC power WS ₅ with sensors 14a and 14b are detected, based on which Based on the instantaneous power Wi calculated in this way and the target instantaneous power Mi, the duty ratio DTi is corrected according to the processing procedure shown in FIG. 6, and feedback is performed so that the waveform of the adjusted DC power WS ₅ matches the target DC power WD _0. Will be controlled.
[0046]
Further, every time the control for one cycle of the target AC power WA ₀ is completed, the total power amount TW is calculated according to the processing procedure shown in FIG. 7 and compared with the preset set power amount SW. Since the coefficient K is corrected, feedback control is performed so that the total power amount TW matches the set power amount SW.
[0047]
In the above description, the case where the lamp lighting AC power having the waveform of FIG. 9D is supplied has been described. However, the waveform is arbitrary, and the waveforms as shown in FIGS. 9B and 9C are of course. In other words, it may be an asymmetric waveform with different power values and application times on the plus side and the minus side.
Moreover, although the case where electric power is adjusted was demonstrated in the above-mentioned description, you may adjust electric power by controlling one of a voltage or an electric current.
Furthermore, as shown in the waveforms of FIGS. 9B to 9D, when the plus side and the minus side of the lamp lighting AC power WA ₀ are equal, even if one cycle is controlled based on the half cycle waveform. good.
[0048]
【The invention's effect】
As described above, according to the present invention, the duty ratio of the power control pulse signal for turning on / off the switching element of the chopper circuit is set based on the target DC power obtained by rectifying the target AC power. Adjusted DC power having a waveform equal to the target DC power is output, and if this is inverted at a predetermined timing, AC power for lamp lighting having a waveform equal to the target AC power can be easily obtained. Since it can be executed by a simple control device such as a single-chip microcomputer that can be incorporated in the lighting circuit, the overall configuration of the device can be simplified and miniaturized, and it can be manufactured at any cost according to the characteristics of the discharge lamp. There is a very excellent effect that the waveform power can be generated.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a discharge lamp lighting device according to the present invention.
FIG. 2 is a circuit diagram showing a lamp power adjustment circuit.
FIG. 3 is a circuit diagram showing a polarity inverting circuit.
FIG. 4 is a waveform diagram showing each power waveform and each control pulse signal.
FIG. 5 is a flowchart showing a processing procedure.
FIG. 6 is a flowchart illustrating a duty ratio correction procedure.
FIG. 7 is a flowchart showing a power coefficient correction procedure.
FIG. 8 is a waveform diagram illustrating a duty ratio correction process.
FIG. 9 is a waveform diagram showing lamp lighting AC power.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ......... Lighting device L ......... Discharge lamp 2 ......... Power supply circuit 3 ......... Lamp power adjustment circuit 4 ......... Polarity inversion circuit 9 ......... FET (switching element)
10 ......... Chopper circuit 11 ......... Smoothing circuit 23 ......... Power waveform setting means 24 ......... Lamp power control means 25 ......... Timing control means

Claims (3)

A chopper circuit (10) for converting a DC constant voltage output from the power supply circuit (2) into DC rectangular wave power by turning on and off the switching element (9) and a smoothing circuit (11) for smoothing the DC rectangular wave power. A lamp power adjustment circuit (3) and a polarity inverter circuit (4) that inverts the adjusted DC power output from the lamp power adjustment circuit (3) at an arbitrary timing to generate AC power for lamp lighting. A lighting device for an electric light,
Discharge lamp (L) can be set in advance to any target AC power waveform to be applied to the power waveform setting means (23),
Based on the instantaneous power value in the minute section of the adjusted DC power output from the lamp power adjustment circuit (3) and the target instantaneous power value of the target DC power obtained by rectifying the waveform of the target AC power in the corresponding minute section. Lamp power control means (24) for turning on and off the switching element (9) of the chopper circuit (10) with a power control pulse signal having a duty ratio set by
Timing control means (25) for outputting a timing control signal for inverting the adjusted DC power output from the lamp power adjusting circuit (3) in synchronization with the target AC power to the polarity inverting circuit (4). ,
The lamp power control means (24) determines the duty ratio of the power control pulse signal for turning on and off the switching element (9), the instantaneous power value of the adjusted DC power output from the smoothing circuit (11), and the target DC A discharge lamp lighting device comprising duty ratio correction means (STP7) for feedback control based on a difference from a target instantaneous power value of a waveform. The power waveform setting means (23)
A memory chip that records a waveform of a target AC power to be applied to the discharge lamp (L);
The discharge lamp lighting device according to claim 1, wherein the lamp power control means (24) is replaceably mounted via a connector.   The discharge lamp lighting device according to claim 1, wherein the power waveform setting means (23) is a memory for recording a waveform of the target AC power supplied by the communication means for recording the target AC power from an external computer.

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