JP4168975B2 - Discharge lamp lighting device and lighting fixture - Google Patents

Description

  The present invention relates to a discharge lamp lighting device and a lighting fixture.

  Dimming ballasts (discharge lamp lighting devices) for discharge lamps typified by fluorescent lamps, the discharge lamp is turned on at high frequency using an inverter circuit that converts low-frequency commercial power into high-frequency light, and input light control A dimming electronic ballast for dimming the discharge lamp by controlling the power supplied to the discharge lamp in accordance with a signal has become common. Such a light control electronic ballast is required to have a stable light control performance that does not cause an unstable state such as flicker even to a low luminous flux.

  In addition, when used for production purposes such as stage lighting, it is also required to reduce flashing and extinction due to unstable conditions immediately after the start of the discharge lamp, and dimming performance closer to that of an incandescent lamp is required. .

  In order to meet these demands, dimming electrons that detect the lighting state of a discharge lamp (for example, a fluorescent lamp) and perform feedback control according to an input dimming signal so that the discharge lamp has a predetermined output. Ballasts are common. As a method using such feedback control, a method of detecting output power to the discharge lamp and performing feedback control is generally used.

  For example, as shown in FIG. 18, a configuration example of a dimming electronic ballast using an integrated circuit L6574 manufactured by ST Microelectronics is described in its application note AN993. This dimming electronic ballast rectifies the AC power supply Vs inputted to the rectifier circuit 2 via the low-pass filter circuit 1, and further obtains a direct current of a predetermined voltage by the chopper circuit 3 and the smoothing capacitor C0. The voltage across the smoothing capacitor C0 is supplied to the half-bridge inverter circuit 4 as a DC power supply. The smoothing capacitor C0 has a series of FET switching elements Q1, Q2 and a resistor R1 at both ends. A circuit is connected, and a resonance circuit composed of a resonance inductor L1, a resonance capacitor C1, and a discharge lamp LA connected in parallel to the resonance capacitor C1 is connected to the series circuit of the switching element Q2 on the low side and the resistor R1 to resonate. The voltage across the capacitor C1 is applied to the discharge lamp LA. The output power of the discharge lamp LA is detected by the voltage across the resistor R1, and the voltage across the voltage and the variable reference voltage Vref that determines the dimming level are compared by the error amplifier EA that constitutes the comparator of the feedback circuit 5. A voltage signal based on the difference is output as a feedback signal OP-out, and the feedback signal OP-out and a control signal Vstr consisting of a voltage signal from the pulse signal generator 7 are added by an adder 6 based on the voltage signal. Thus, the frequency finv of the pulse signal from the oscillator 8 is modulated.

  The driver circuit 9 generates a gate signal for alternately turning on / off the switching elements Q1, Q2 based on the oscillation signal of the oscillator 8. The chopper control circuit 10 controls the chopper circuit 3 so that its output voltage becomes a predetermined voltage.

  The capacitor Cfb and the resistor Rfi constitute a delay element of the error amplifier EA.

  FIG. 19 shows signals at various parts in FIG. 18, FIG. 19 (a) shows the control signal Vstr, FIG. 19 (b) shows the feedback signal OP-out, FIG. 19 (c) shows the frequency finv of the oscillator 8, and FIG. ) Shows the lamp voltage Vla, and FIG. 19E shows the light output of the discharge lamp LA.

  By the way, in the method of detecting and feeding back the output power as in this conventional example, the control of the lamp dimming ratio up to several percent is the limit.

  Further, in the case where light control is performed to an extremely low luminous flux region where the light control ratio is, for example, several percent or less, there is a device that performs feedback control by detecting the impedance of the discharge lamp.

  By the way, paying attention to reducing the lamp flash generated when starting the discharge lamp LA, there are problems that a method of applying a DC voltage to the discharge lamp LA and that a strong feedback leads to an increase in the flash. It was.

  That is, in the conventional example shown in FIG. 18, the filament is preheated until the discharge lamp LA is started, and the control signal Vstr is gradually increased after pre-preheating for a predetermined time as shown in FIG. Set the starting period to be raised. The feedback signal OP-out of the feedback circuit 5 is saturated at the maximum output from the preheating period until the discharge lamp LA described later starts.

  As the control signal Vstr increases, the lamp voltage Vla of the discharge lamp LA also increases as shown in FIG. When the lamp voltage Vla reaches the starting voltage of the discharge lamp lA, the discharge lamp LA starts discharging. Immediately after that, the dimming lighting mode period in which the feedback circuit 5 responds and controls the light output of the discharge lamp lA to the target output as shown in FIG. However, the light output increases during the response period of the feedback circuit 4 and flashing occurs during the period X.

  In other words, when the discharge lamp LA is not yet lit, the feedback circuit 5 tries to maximize the output of the inverter circuit 4, and when it is lit, it responds to reduce it to the target output. This is because the above light is generated.

  As a technique for reducing the flash, a method of lighting with a low luminous flux while applying a periodic high voltage pulse voltage to a discharge lamp has been proposed (for example, Patent Document 1).

However, even in the method of applying a periodic high voltage pulse, the start is unstable depending on the lamp condition, and a high pulse voltage is required for a reliable start. Therefore, the illuminance increased at the start and a flash was generated.
JP 2003-327881 A

  The device that detects the output of the discharge lamp and performs feedback control as described in the prior art has the effect of improving the stability of the light, but it has caused flashing at the start.

Even in the method of lighting with a low luminous flux by periodically applying a high voltage pulse, a high starting voltage is required at the time of starting, and thus flashing cannot be avoided.

  The present invention has been made in view of the above points. The object of the present invention is to automatically switch between a condition for starting a discharge lamp and a condition for stable lighting, and at the time of starting. It is an object of the present invention to provide a discharge lamp lighting device and a lighting fixture that eliminate the flash of the discharge lamp.

  In order to achieve the above object, according to the invention of the discharge lamp lighting device of claim 1, an inverter circuit connected to the output of the DC power supply, an LC resonance circuit connected to the output of the inverter circuit, and the LC resonance A discharge lamp connected in parallel to a capacitor of the circuit; a driver circuit for controlling on / off of a switching element of the inverter circuit; and the frequency of the oscillation signal according to the level of the input frequency modulation signal. An oscillator that gives an operation timing to the driver circuit with an oscillation signal, a pulse signal generator that generates a control signal in which a pulse signal is superimposed on a voltage of a non-pulse part, and the emission The signal level of the detection output corresponding to the output of the lamp is compared with the target value, and the feedback signal for correcting the oscillation frequency of the signal level according to the difference is compared. A signal obtained by adding the signal level of the control signal of the pulse signal generator and the signal level of the feedback signal of the feedback circuit as the frequency modulation signal. An adder for supplying to an oscillator; and a pulse control circuit for controlling a pulse signal waveform generated from the pulse signal generator, wherein the pulse control circuit gradually reduces the amplitude of the pulse portion after the discharge lamp is started and lit. The pulse signal generator is controlled so that the feedback circuit performs feedback control so that the output of the discharge lamp is constant.

  According to the invention of the discharge lamp lighting device of the first aspect, by smoothly changing the starting condition for applying the pulse voltage to the discharge lamp to start the lamp and the lighting condition for the pulse voltage sufficient for the discharge lamp to be stably lit. Thus, it is possible to provide a discharge lamp lighting device that can realize stable start of the discharge lamp by reducing the flashing at the start and suppressing the disappearance and the change of the start time due to the change of the discharge lamp discharge characteristics.

  In the invention of the discharge lamp lighting device of claim 2, in the invention of claim 1, the feedback circuit operates when the pre-heating for the filament of the discharge lamp is completed.

  According to the invention of the discharge lamp lighting device of the second aspect, even when the feedback circuit is simplified, the flashing at the start can be reduced.

  According to a third aspect of the present invention, there is provided a discharge lamp lighting device according to the first aspect, further comprising a lighting determination circuit that detects lighting by detecting the output of the discharge lamp, and the pulse control circuit determines lighting of the lighting determination circuit. A control operation for gradually decreasing the amplitude of the pulse portion is started in synchronization with the output of the signal.

  According to the invention of the discharge lamp lighting device of the third aspect, it is possible to shorten the time from the start to the lighting while reducing the flashing at the start of the discharge lamp.

  A discharge lamp lighting device according to a fourth aspect of the present invention includes the lighting determination circuit that determines the lighting by detecting the output of the discharge lamp according to the first aspect of the invention, and the feedback determination circuit includes the discharge determination circuit. The operation is started after the lighting at the start of the electric light is determined.

  According to the invention of the discharge lamp lighting device of the fourth aspect, even if the feedback circuit is simplified, the time from the start to the lighting can be shortened while reducing the flash at the start of the discharge lamp.

  According to a fifth aspect of the invention of the discharge lamp lighting device, in the first aspect of the present invention, the discharge lamp lighting device includes a lighting determination circuit that detects lighting by detecting the output of the discharge lamp, and the pulse control circuit includes a lighting determination circuit that lights up. At the same time as outputting the determination signal, the amplitude of the pulse part or the area per unit time is reduced, and then the control operation is started to gradually reduce the amplitude of the pulse part.

  According to the invention of the discharge lamp lighting device of the fifth aspect, it is possible to reduce the flashing at the start-up even for the discharge lamp in which flashing is easily generated.

  In the invention of the discharge lamp lighting device of claim 6, in the invention of claim 1, a lighting determination circuit for detecting lighting by detecting the output of the discharge lamp, and a lighting detection signal from the lighting determination circuit are input. And a delay circuit that outputs the signal with a delay of a predetermined time, and when the lighting detection signal is output from the delay circuit, the pulse control circuit starts the control operation by reducing the amplitude of the pulse part.

  According to the invention of the discharge lamp lighting device of the sixth aspect, it is possible to suppress the flashing at the start-up even for the discharge lamp that tends to go out.

  In the invention of the discharge lamp lighting device of claim 7, in the invention of claim 3, the time for the pulse control circuit to reduce the amplitude of the pulse part is varied to make the starting period of the discharge lamp constant. It is characterized by.

  According to the discharge lamp lighting device of the seventh aspect of the present invention, it is possible to start stably even by controlling a plurality of discharge lamps by correcting the timing that changes due to variations in startability of the discharge lamp.

In the invention of a discharge lamp lighting device according to claim 8, in any one of the claims 3 to 7, before Symbol lighting determining circuit, a low-pass filter circuit for removing high-frequency component of the output detection signal of said feedback circuit The low-pass filter circuit has a cut-off frequency equal to or lower than the frequency of the pulse signal, and the lighting determination timing is performed immediately before application of the pulse voltage to the discharge lamp in synchronization with the operation of the pulse signal generator. Features.

  According to the discharge lamp lighting device of the eighth aspect, the lighting determination circuit can improve the accuracy of determining whether the discharge lamp is turned on.

  In the invention of the discharge lamp lighting device according to claim 9, in the invention of any one of claims 1 to 8, the feedback circuit includes a low-pass filter circuit having a sufficient attenuation factor with respect to a commercial power supply frequency, and the low-pass filter circuit. A circuit that bypasses the low-pass filter circuit, and a signal that bypasses the low-pass filter circuit at the time of start-up is used as a feedback comparison value that is input to the comparator, and variable control of the amplitude of the pulse unit by the pulse control circuit Is completed, the signal that has passed through the low-pass filter circuit is used as a feedback comparison value.

  According to the discharge lamp lighting device of the ninth aspect, it is possible to shorten the time from the start to the dimming change possible.

  According to a tenth aspect of the present invention, there is provided the discharge lamp lighting device according to any one of the first to ninth aspects.

  According to the lighting device of the tenth aspect, it is possible to provide the lighting device having the effects of the first to ninth aspects of the invention.

  The present invention can reduce the flashing at the time of starting by smoothly changing the starting condition for applying a pulse voltage to the discharge lamp to start the lamp and the lighting condition for the pulse voltage sufficient for the discharge lamp to stably operate. It is possible to provide a discharge lamp lighting device that realizes stable start of a discharge lamp and to provide a lighting fixture by suppressing the disappearance and the change of the start time due to the change in the discharge characteristics of the lamp.

Embodiments of the present invention will be described below.
(Embodiment 1)
FIG. 1 shows a circuit configuration of the present embodiment. In the present embodiment, a chopper circuit 3 is connected to an AC power source Vs through a noise blocking filter circuit 1 and a rectifier circuit 2 as shown in FIG. The chopper circuit 3 obtains a DC power supply having a voltage required for the inverter circuit 4 at the next stage.

  The inverter circuit 4 is constituted by a half-bridge type inverter circuit composed of switching elements Q1, Q2 and the like connected in parallel to the smoothing capacitor C0 connected to the output of the chopper circuit 3, and the switching elements Q1, Q2 Are alternately turned on and off by the driver circuit 9.

  An LC resonance circuit composed of a series circuit of a resonance inductor L1 and a resonance capacitor C1 is connected to the switching element Q1 via a DC cut capacitor C2, and a discharge lamp LA and a resistor RN1 are connected in parallel to the resonance capacitor C1. It is.

  The discharge lamp LA is made of a fluorescent lamp, and has a filament (not shown) at both ends. For example, the filament is connected to a pair of preheating windings (not shown) provided in the resonance inductor L1, and a preheating current is obtained. Is supposed to flow. In this case, the preheating current is limited to a predetermined magnitude by interposing a current limiting capacitor between the preheating winding and the filament.

  An oscillation signal having a frequency finv of the oscillator 8 is input to the driver circuit 9. The frequency control of the oscillator 8 inputs the sum of the voltage levels of the two signals. One signal is a control signal Vstr output from the pulse signal generator 7 and becomes a periodic frequency modulation signal, and the other signal is a feedback signal OP-out output from the feedback circuit 5. The feedback signal OP-out is determined by a feedback circuit 5 including an error amplifier EA including an error amplifier and a network including a series circuit of resistors RN1 to RN3.

  The feedback circuit 5 functions to detect the discharge lamp output and adjust the frequency finv of the oscillator 8 so that the discharge lamp output becomes a constant value. That is, the output voltage of the chopper circuit 3, that is, the voltage obtained by dividing the voltage across the smoothing capacitor C0 by a network composed of a series circuit of resistors RN1 to RN3 is applied to both ends of the discharge lamp LA. Accordingly, a voltage is generated across the resistor RN3.

  If this voltage is controlled to be constant, the impedance of the discharge lamp LA becomes constant, so that the light output of the discharge lamp LA is also constant. In other words, the voltage across the resistor RN3 is detected as the discharge lamp output, and the voltage is controlled to be constant.

  The pulse signal generator 7 is controlled so that the period and amplitude of the pulse part and the voltage level of the non-pulse part are controlled by the pulse control circuit 11, and the inverter frequency and the modulation degree thereof are changed according to the start time or dimming of the discharge lamp LA. The signal Vstr is output.

  FIG. 2A shows the configuration of the pulse signal generator 7. The triangular wave pulse signal A shown in FIG. 2B and the DC signal B shown in FIG. A control signal Vstr is generated.

  That is, the MAX circuit 70 has a function of outputting a high signal among the inputs of the signals A and B as shown in FIG. 2D, and is actually composed of an ideal diode circuit or the like, and the pulse control circuit 11 Thus, the period and height of the triangular wave of signal A and the DC level of signal B are controlled. As a result, the control signal Vstr, which is a combined output, can arbitrarily change the amplitude / period of the pulse part and the voltage level of the non-pulse part.

  When the preheating control in the preheating control (preceding preheating) period in which the filament is heated before starting the discharge lamp LA is completed, the preheating start control circuit 12 generates a signal for causing the pulse control circuit 11 to start the start control. FIG. 3 shows a diagram showing the operation state of the present embodiment.

  3A shows the control signal Vstr, FIG. 3B shows the feedback signal OP-out, FIG. 3C shows the frequency finv of the oscillation signal of the oscillator 8, and FIG. 3D shows the lamp voltage Vla. FIG. 4E shows a timing chart of the light output of the discharge lamp LA.

  Thus, when the AC power source Vs is input to the discharge lamp lighting device and the chopper control circuit 10 and the chopper circuit 3 operate, the preheating start control circuit 12 stops the control operation of the pulse control circuit 11 for a certain time. To.

  In the meantime, the level of the control signal Vstr is low, the frequency finv of the oscillation signal of the oscillator 8 is high as shown in FIG. 3C, and the inverter circuit 4 performs an operation of preheating the filament of the discharge lamp LA. That is, this period is the preceding preheating period T1.

  Eventually, when preheating ends at timing t1 shown in FIG. 3A, a start start signal is input from the preheat start control circuit 12 to the pulse control circuit 11, and start control is started. Upon receiving the start signal, the pulse control circuit 11 controls the pulse signal generator 7 so that the peak of the control signal Vstr becomes large.

  The control operation of the pulse control circuit 11 at this time is performed so that the pulse part gradually increases as shown in FIG. 3A without changing the non-pulse part of the control signal Vstr. Therefore, the oscillation frequency finv of the oscillator 8 controlled by the signal of the level obtained by adding the feedback signal OP-out and the control signal Vstr shown in FIG. 3B by the adder 6 is as shown in FIG. It becomes low at the peak of the pulse part of the control signal Vstr.

  The inverter circuit 4 has a load circuit including an LC resonance circuit composed of an inductor L1 and a capacitor Cf, and operates at a frequency higher than the normal resonance frequency, but corresponds to the peak of the pulse portion of the control signal Vstr as described above. Since the switching elements Q1 and Q2 are driven by the driver circuit 9 in response to an oscillation signal whose frequency finv decreases in a direction approaching the resonance frequency, the resonance voltage increases accordingly, and a pulse voltage due to resonance is generated at both ends of the discharge lamp LA. Is applied as shown in FIG. 3D.

  The control signal Vstr output from the pulse signal generator 7 under the control of the pulse control circuit 11 does not change when the peak value reaches a certain peak level, and maintains the starting state for a certain time. That is, a transition is made from the preceding preheating period T1 to the starting fixed period T3 through the starting period T2.

  At this time, if the discharge lamp LA is not lit, the optical output of the discharge lamp LA is 0. Therefore, the feedback obtained by taking in the voltage across the resistor RN3 corresponding to the discharge lamp output via the resistor Rfi as a delay element. The feedback signal OP-out output from the error amplifier EA of the circuit 5 is saturated to the maximum level.

  When the above-described resonance voltage (pulse voltage) reaches a level at which the discharge lamp LA is started, the discharge lamp LA is turned on. However, since the output level of the discharge lamp LA (the voltage across the resistor RN3 is equal to or lower than the comparison value (target value) Vref of the error amplifier EA of the feedback circuit 5), the feedback signal OP-out is still saturated to the maximum level. is there.

  After the discharge lamp LA is lit, the pulse control circuit 11 performs control to gradually increase the level of the non-pulse part of the control signal Vstr output from the pulse signal generator 7 at timing t2.

  That is, as the level of the non-pulse part of the control signal Vstr increases, the frequency finv of the oscillation signal of the oscillator 8 decreases, so that the output of the discharge lamp LA increases. This period is the transition mode period T4. From this time, the discharge lamp output becomes equal to or higher than the comparison value Vref of the error amplifier EA of the feedback circuit 5, and the feedback circuit 5 sets the level of the feedback signal OP-out so as to increase the frequency finv in order to keep the discharge lamp output constant. Perform the lowering action.

  Here, by making the rate of increase in the level of the non-pulse part of the control signal Vstr slower than the response speed of the feedback circuit 5, the feedback circuit 5 generates a feedback signal OP-out that can keep the output of the discharge lamp LA constant. It can be generated.

  Further, when the frequency finv of the oscillation signal of the oscillator 8 corresponding to the non-pulse part of the control signal Vstr of the pulse signal generator 7 becomes a predetermined level, the feedback signal OP-out of the feedback circuit 5 is also within the control range. Is set.

  Looking at the lamp voltage Vla, the level of the non-pulse part of the control signal Vstr output from the pulse signal generator 7 is changed while keeping the light output of the discharge lamp LA constant as shown in FIG. Then, the peak voltage of the pulse part becomes smaller.

  When the control by the pulse control circuit 11 is finished, the dimming lighting mode period T5 is reached, and the feedback target value (the comparison value Vref of the error amplifier EA) and the level of the non-pulse part of the control signal Vstr are set according to the dimming input signal. Dimming can be performed freely by changing.

  As described above, the present embodiment uses the feedback circuit 5 to determine the conditions necessary for starting the discharge lamp LA and the conditions under which the discharge lamp LA is stably lit while maintaining the light output of the discharge lamp LA constant. The light output of LA can be automatically switched without a seam.

That is, generally, the condition necessary for starting the discharge lamp LA is a high pulse voltage, and the condition for stable lighting is a low pulse voltage compared to that, but in this embodiment, the switching speed of the condition is set as a feedback circuit. 5 is performed in accordance with the response speed determined by the time constant of the resistance Rif and the capacitance Cfb of the delay element, and the starting condition for starting by giving a high pulse voltage to the discharge lamp LA and the pulse voltage applied to the discharge lamp LA are lowered. By smoothly changing the lighting conditions for stable lighting, it is possible to reduce the flashing at the start of the discharge lamp LA and realize stable lighting of the discharge lamp LA at the dimming lower limit.
(Embodiment 2)
The present embodiment is a simplified version of the function of the first embodiment, and FIG. 4 shows the configuration of the present embodiment.

  In other words, in this embodiment, the pulse signal generator 7 controlled by the pulse control circuit 11 is controlled only for the non-pulse part of the control signal Vstr, and the target value change for changing the level of the comparison value (target value) Vref of the feedback circuit 5 is performed. The second embodiment is different from the first embodiment in that the circuit 13 is provided. Since other configurations are the same as those of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted. The target value changing circuit 13 may be constituted by a simple switching element or the like.

  The target value changing circuit 13 and the pulse control circuit 11 start to operate in response to the preheating end timing of the preheating start control circuit 12.

  Next, the operation of this embodiment will be described with reference to FIG.

  Thus, now, the preheating period T1 shown in FIG. 5 (a) for preheating the filament of the discharge lamp LA is completed, and the preheating start control circuit 12 starts to start the pulse control circuit 11 and the target value changing circuit 13. When the signal is given, the start control signal is received, and the pulse control circuit 11 starts the operation of generating the control signal Vstr from the pulse signal generator 7 as shown in FIG.

  Further, the target value changing circuit 13 sets the target value Vref to a low level as shown in FIG. 5B so that the feedback circuit 5 does not operate during the preceding preheating period T1, and the feedback circuit 5 is set with the end of the preceding preheating period T1. Step to a higher level to work.

  As a result, the feedback circuit 5 operates, and the feedback signal OP-out becomes larger as shown in FIG. 5C in response waveforms of the resistor Rfi and the capacitor Cfb which are delay elements.

  For this reason, the signal level output from the adder 6 increases, and therefore the frequency finv of the oscillation signal of the oscillator 8 shifts to a lower frequency as shown in FIG. As the frequency finv of the oscillation signal of the oscillator 8 decreases, the both-ends voltage (lamp voltage) Vla of the discharge lamp LA increases as shown in FIG. Eventually, the discharge lamp LA is turned on, and the feedback signal OP-out of the feedback circuit 5 converges.

  Next, the pulse control circuit 11 controls the level of the non-pulse part of the control signal Vstr to raise it slower than the response speed of the feedback circuit 5. Accordingly, the frequency finv of the oscillation signal of the oscillator 8 is controlled so as to keep the output of the discharge lamp LA constant by the feedback signal OP-out of the feedback circuit 5. As a result, the pulse peak of the voltage Vla across the discharge lamp LA gradually decreases.

  When the non-pulse part of the control signal Vstr reaches a predetermined value and is controlled to stop the increase, the change of the feedback signal OP-out of the feedback circuit 5 also stops.

  As described above, in the present embodiment, it is only necessary to control the level of the non-pulse part of the control signal Vstr for the pulse signal generator 7 of the pulse control circuit 11, which can be simplified. For example, if the pulse peak level and the level of the non-pulse part are variable, two signal variable means are required and a triangular pulse signal is good considering the stress of the inverter circuit 4, so that the peak of the pulse part The variable of requires complicated control. However, in this embodiment, one means for changing the level of the non-pulse part may be used, so that the circuit configuration can be simplified. Moreover, if this embodiment is used, the condition at the time of starting and the condition at the time of the light control lower limit can be switched smoothly, and the flashing at the time of starting of the discharge lamp LA can be reduced.

Note that the periods T4 and T5 in FIG. 5 correspond to the transition mode period T4 and the dimming lighting mode period T5 in FIG.
(Embodiment 3)
FIG. 6 shows this embodiment. In this embodiment, as shown in the figure, a lighting determination circuit 14 for detecting lighting of the discharge lamp LA is provided. The lighting determination circuit 14 takes in, for example, a current change caused by the impedance change of the discharge lamp LA, determines that the discharge lamp LA has started when the current change falls below a certain impedance, and outputs a lighting determination signal. To do.

  In terms of the circuit, a capacitor C3 is connected in parallel to the resistor RN3, the current flowing due to the impedance change of the discharge lamp LA changes, and the voltage across the parallel circuit of the resistor RN3 and the capacitor C3 caused by the current change is taken in. By comparing the voltage with a threshold value, it is detected that the impedance of the discharge lamp LA has become below a certain level, and lighting determination is performed.

  In this embodiment, a start start signal of the preheating start control circuit 12 and a lighting determination signal from the lighting determination circuit 14 are input to the pulse control circuit 11 to control the operation of the pulse control circuit 11.

  Next, the operation of this embodiment will be described.

  Now, when the preceding preheating period T1 shown in FIG. 7A for performing the preheating for the filament of the discharge lamp LA is completed, and the start start signal of the preheating start control circuit 12 is input to the pulse control circuit 11 at the timing t1, The pulse control circuit 11 controls the pulse signal generator 7 so that the peak of the pulse portion of the control signal Vstr gradually rises as shown in FIG.

  Then, as the peak of the pulse portion of the control signal Vstr rises, the frequency of the oscillation signal of the oscillator 8 decreases, so that a pulse voltage is applied to both ends of the discharge lamp LA in the same manner as described above, and the voltage Vla between both ends is shown in FIG. ) Go up as shown. When the voltage Vla applied to the discharge lamp LA becomes the starting voltage of the discharge lamp LA, the discharge lamp LA is turned on.

  When the discharge lamp LA is lit, the voltage Vfb across the capacitor C3 rises as shown in FIG. 7B and exceeds a predetermined threshold value, whereby a lighting determination signal is output from the lighting determination circuit 14 to the pulse control circuit 11. Is done.

  Upon receiving the lighting determination signal, the pulse control circuit 11 controls the pulse signal generator 7 so as to stop the rise of the peak of the pulse part of the control signal Vstr, and the non-pulse part of the control signal Vstr is shown in FIG. The control mode is switched to a control operation that increases slower than the response speed of the feedback signal OP-out of the feed hack circuit 5 shown, and the transition mode period T4 starts. As a result, by increasing the non-pulse part of the control signal Vstr, the peak of the pulse voltage applied to the discharge lamp LA is maintained while keeping the light output of the discharge lamp LA constant as shown in FIG. Can be reduced.

  7D shows the frequency finv of the oscillation signal of the oscillator 8, and T5 in FIG. 7A shows the dimming lighting mode period.

As described above, the present embodiment can shorten the time from start to lighting by using the lighting determination circuit 14. It goes without saying that the same effect can be obtained even if the lighting determination is used in the same configuration as that of the second embodiment.
(Embodiment 4)
FIG. 8 shows the configuration of the present embodiment. In the present embodiment, as shown in the figure, the target value changing circuit 13 used in the second embodiment is added to the configuration of the third embodiment.

  The other configuration is the same as the configuration shown in FIG.

  Next, the operation of this embodiment will be described.

  Now, as shown in FIG. 9 (a), when the preceding preheating period T1 in which the filament of the discharge lamp LA is preheated is completed and the starting period T2 is reached, the preheating start control circuit 12 controls the start start signal at timing t1. Input to the circuit 11. Thereby, the pulse generator 8 is controlled by the pulse control circuit 11, and the peak value of the output control signal Vstr is increased as shown in FIG. As a result, the frequency finv of the oscillation signal of the oscillator 8 corresponding to the peak of the pulse portion of the control signal Vstr decreases as shown in FIG. 9E, and as a result, the resonance voltage of the LC resonance circuit of the inverter circuit 4 increases. Thus, the voltage Vla across the discharge lamp LA rises as shown in FIG.

  When the voltage Vla applied to the discharge lamp LA rises to the starting voltage of the discharge lamp LA, the discharge lamp LA starts, and this start increases the voltage Vfb across the capacitor C3 as shown in FIG. 9B. When this voltage exceeds a threshold value, the lighting determination circuit 14 determines that the discharge lamp LA has been turned on, and outputs a lighting determination signal to the target value changing circuit 13 and the pulse control circuit 11.

  The target value change circuit 13 receives the lighting determination signal from the lighting determination circuit 14 and raises the target value Vref of the feedback circuit 5 as shown in FIG.

  As a result, the feedback signal OP-out of the feedback circuit 5 gradually increases due to the action of increasing the lamp power as shown in FIG. This rising period is the transition mode period T4.

  On the other hand, when receiving the lighting determination signal from the lighting determination circuit 14, the pulse control circuit 11 controls the pulse signal generator 7 so as to lower the peak of the pulse portion of the control signal Vstr. The speed for reducing this peak is slower than the response speed of the feedback circuit 5. As a result, the peak voltage of the voltage Vla applied to the discharge lamp LA can be changed while stabilizing the light output shown in FIG. 9G to the target value.

  T5 indicates the period of the dimming lighting mode.

  As described above, when this embodiment is used, it is possible to perform lighting with reduced flash without changing the level of the non-pulse part of the control signal Vstr at the time of starting. That is, the configuration of the pulse control circuit 11 can be simplified. Further, since the voltage of the non-pulse part can be kept constant in the starting state in which the peak of the starting pulse applied to the discharge lamp LA is gradually increased, the light output at the moment of starting the lamp can be suppressed.

As described above, the present embodiment achieves both simplification of the pulse circuit and start control performance.
(Embodiment 5)
The present embodiment is a further improvement in the configuration of the third embodiment with a discharge lamp LA that is likely to generate flash.

  Since the configuration is the same as that of the third embodiment, the configuration of FIG. 6 is referred to.

  Next, the operation of this embodiment will be described with reference to FIG.

  When the preceding preheating period T1 in which preliminarily preheating the filament of the discharge lamp LA ends as shown in FIG. 10A and the start control is started, a start start signal is input to the pulse control circuit 11 from the preheat start control circuit 12. Then, the pulse control circuit 11 controls the pulse signal generator 7 to gradually increase the peak of the pulse portion of the control signal Vstr shown in FIG.

  Then, in the starting period T2 until the discharge lamp LA is started, the peak voltage of the voltage Vla applied to the discharge lamp LA corresponding to the rise of the peak of the pulse portion of the control signal Vstr is as shown in FIG. As a result, the discharge lamp LA is turned on, and the light output of the discharge lamp LA is as shown in FIG.

  Immediately thereafter, the voltage Vfb of the capacitor C3 rises as shown in FIG. 10B, and the lighting determination circuit 14 determines the lighting of the discharge lamp LA from the increase of the voltage Vfb in the same manner as described above, and generates a lighting determination signal. Output to the pulse control circuit 11.

  Upon receiving the signal, the pulse control circuit 11 controls the pulse signal generator 7 to reduce the peak level of the pulse portion of the control signal Vstr to a predetermined level.

  As a method of reducing the peak level, there is a method of reducing the pulse height as shown in FIG. 11A, but in addition to that, as shown in FIG. As shown in c) and (d), the same effect can be obtained by reducing the area per unit time of the pulse such as the combination of the magnitude of the pulse and the width of the pulse.

  Thereafter, the pulse control circuit 11 controls the pulse signal generator 7 to gradually increase the level of the non-pulse part of the control signal Vstr, and the feedback signal OP− from the feedback circuit 5 shown in FIG. Change according to the response speed of out.

Thus, in the discharge lamp LA having a large difference between the starting voltage and the lighting voltage, there is a problem that the light emission at the time of applying the starting pulse is large. In this embodiment, the level of the pulse voltage applied to the discharge lamp LA immediately after lighting is set. By lowering it, it is possible to switch between the start pulse and the stable lighting while suppressing the flash.
(Embodiment 6)
FIG. 12 shows the configuration of this embodiment. As shown in the figure, this embodiment is different from the configuration of the third embodiment shown in FIG. 6 in that the output of the lighting determination circuit 14 is connected to the pulse amplitude circuit 11 via a delay circuit 15.

  Next, the operation of this embodiment will be described.

  Now, when the preceding preheating period T1 shown in FIG. 13A ends, a start start signal is input from the preheat start control circuit 12 to the pulse control circuit 11 at timing t1, and when the start control is entered, the pulse control circuit 11 The pulse signal generator 11 is controlled to gradually increase the peak of the pulse portion of the control signal Vstr. As a result, a pulse voltage whose peaks gradually increase at both ends of the discharge lamp LA is periodically applied to the discharge lamp LA. When the pulse voltage reaches a level at which the discharge lamp LA is started, the discharge lamp LA is started and lit. To do. Immediately after that, when the lighting determination circuit 14 determines lighting by the rise of the voltage Vfb across the capacitor C3, the lighting determination signal is output to the delay circuit 15. The delay circuit 15 delays the input lighting determination signal for a predetermined time and then sends it to the pulse control circuit 11.

  When this lighting determination signal is input, the pulse control circuit 11 controls the pulse signal generator 7 to gradually increase the signal level of the non-pulse part of the control signal Vstr. That is, a certain time until the lighting determination signal enters the pulse control circuit 11 is a delay period T6 from the start period T2 to the transition mode period T4. Thereafter, the operation proceeds to the transition mode period T4 and the dimming lighting mode period T5 through the same operation as in the third embodiment. 13B shows the feedback signal OP-out, and FIG. 13C shows the optical output.

  When the delay circuit 15 is not provided as in the present embodiment, the control signal Vstr is controlled as shown in FIG. 13 (d) as shown in FIG. 13 (d), and the feedback signal OP-out is shown in FIG. 13 (e). On the other hand, depending on the state and variation of the discharge lamp LA, the state may become unstable immediately after starting. In particular, it has been confirmed that this is likely to occur when the discharge lamp LA is left unlit or left for a long time. Therefore, when the delay circuit 15 is not provided, the light output immediately after lighting may become 0 as shown in FIG.

  In order to light the discharge lamp LA in such a state, it is necessary to continue to provide a high pulse voltage. However, this unstable state is often eliminated in a short time, and the unstable state disappears in a period of about several tens of ms.

On the other hand, in the present embodiment, the delay circuit 15 delays the input of the lighting determination signal to the pulse control circuit 11 for a certain time, thereby providing a period T6 for applying a high pulse voltage to the discharge lamp LA. It is possible to prevent the discharge lamp LA from disappearing by performing control to decrease the pulse voltage after stabilization.
(Embodiment 7)
In the case of the above-described third embodiment, when changing from the end of the preceding preheating period T1 to the starting state, the pulse control circuit 11 controls the pulse signal generator 7 to gradually increase the peak of the pulse portion of the control signal Vstr. As a result, the pulse voltage applied to the discharge lamp LA is increased, and the discharge lamp LA is started and lit. At this time, when the discharge lamp LA is very likely to be lit, the pulse control circuit 11 is lit at an early time from the start of the control for gradually increasing the peak of the pulse portion of the control signal Vstr, and the pulse control circuit 11 controls the control signal by the lighting determination signal corresponding to the lighting. Control for increasing the peak of the pulse portion of Vstr is stopped, and the control shifts to control for gradually increasing the signal of the non-pulse portion. On the other hand, when it is difficult to attach the discharge lamp LA, the discharge lamp LA is lit at the end of the control for gradually increasing the peak of the pulse portion of the control signal Vstr. For this reason, when the light is turned on late, when the period during which the signal level of the non-pulse part of the control signal Vstr is gradually increased (transition mode period T4) is constant, the mode shifts to the dimming lighting mode T5 as compared with the case where the light is turned on early. Becomes slower.

  Therefore, the present embodiment is characterized in that, for example, the control operation of the pulse control circuit 11 of the third embodiment is adjusted as follows. That is, when the discharge lamp LA is lit early as shown in FIG. 14 (a), when it is lit late as shown in FIG. 14 (b), that is, when the starting period T2 is short and long, the control signal Vstr The period for raising the signal level of the non-pulse part is adjusted so that the end timing of the transition mode period T4 for raising the non-pulse part coincides. As a result, the transition delay to the dimming lighting mode period T5 due to the lighting delay can be prevented, and the start period T2 and the transition mode period T4 can be combined to make the period constant.

Since the operation other than the operation of the pulse control circuit 11 is basically the same as that of the third embodiment, the illustration and explanation of the configuration and the explanation of the operation other than the above are omitted. Similarly, it is needless to say that the present invention can be applied to the pulse control circuit 11 of another embodiment that performs control so as to increase the signal level of the non-pulse part of the control signal Vstr after lighting.
(Embodiment 8)
It is important that the lighting determination circuit 14 used in the third embodiment or the like makes a quick and accurate lighting determination in order to suppress flashing at the start of the discharge lamp LA. Therefore, the time constant of the input filter of the lighting determination circuit 14 is made smaller than the cycle Tpls of the pulse voltage applied to the discharge lamp LA as shown in FIG. Further, as shown in FIG. 15B, the lighting determination timing ts is set to be performed before application of the pulse voltage. That is, by making the time constant of the input filter smaller than the pulse period Tpls, high frequency voltage components unnecessary for detection are removed, and both ends of the capacitor C3 which is an impedance change signal of the discharge lamp LA between pulse voltages necessary for detection. The voltage Vfb is extracted. Then, the threshold value determination of the lighting determination circuit 14 is performed at a timing immediately before the application of the pulse voltage, the lighting of the discharge lamp LA is determined, and the lighting determination signal is output to the pulse control circuit 11 to cause the flash. Application of the starting high voltage pulse immediately after starting can be prevented.

In addition, since it can apply to embodiment using the lighting determination circuit 14, illustration and description of another structure and description of operation | movement are abbreviate | omitted.
(Embodiment 9)
By the way, the feedback circuit 5 for keeping the output of the discharge lamp LA used in each embodiment constant keeps the output of the discharge lamp LA constant at the start of the discharge lamp LA, and the amplitude of the pulse voltage applied to the discharge lamp LA. The feedback signal OP-out is output so as to be variable, but the response speed is slow. This is because the feedback circuit 5 operates after removing various noises. For example, a filter circuit (Cfb, Rfi) having sufficient attenuation with respect to noise of the commercial power supply frequency is required. However, such a filter circuit is necessary at the time of stable lighting, but is not necessary in a short period such as at the time of starting. Therefore, the present embodiment is an improvement of the feedback circuit 5, and as shown in FIG. 16, the voltage Vfb across the resistor RN3, which is an output detection signal of the discharge lamp LA, is converted into an error via the low-pass filter circuit 16. The switch element SW1 is used to switch the path that is input to the amplifier EA and the path that is input to the error amplifier EA without passing through the low-pass filter circuit 16. That is, in the transition mode period T4 immediately after start-up, the switch element SW1 is turned on and the low-pass filter circuit 16 is bypassed to design the transition time to be short, so that the start-up time can be shortened. It is to be noted that the same effect can be obtained even when the time constant of the low-pass filter circuit 16 can be freely changed and operated in accordance with the transition time.

Since other configurations may be the configurations of any of the above-described embodiments, illustration and description of other configurations and descriptions of operations are omitted.
(Embodiment 10)
This embodiment relates to a lighting fixture applicable to the first to ninth embodiments, and the discharge lamp lighting device of any of the above-described embodiments is housed in a fixture main body 18 shown in FIG. 17 as a dimming electronic ballast. The lighting fixture is configured to turn on the discharge lamp LA mounted between the sockets 17 and 17 disposed at both ends of the lower surface of the fixture body 18. Of course, in the case of two or more lighting fixtures, the number of discharge lamp lighting devices may correspond to the number of discharge lamps.

1 is a circuit diagram of Embodiment 1. FIG. (A) is a circuit diagram of the pulse signal generator of Embodiment 1, and (b) to (d) are waveform diagrams for explaining the operation of the pulse signal generator. 3 is a timing chart for explaining the operation of the first embodiment. FIG. 6 is a circuit diagram of a second embodiment. 6 is a timing chart for explaining the operation of the second embodiment. FIG. 6 is a circuit diagram of a third embodiment. 10 is a timing chart for explaining the operation of the third embodiment. FIG. 6 is a circuit diagram of a fourth embodiment. 10 is a timing chart for explaining the operation of the fourth embodiment. 10 is a timing chart for explaining the operation of the fifth embodiment. FIG. 10 is an explanatory diagram of a pulse part of a control signal according to the fifth embodiment. FIG. 10 is a circuit diagram of a sixth embodiment. 10 is a timing chart for explaining the operation of the sixth embodiment. 10 is a timing chart for explaining the operation of the seventh embodiment. 10 is a timing chart for explaining the operation of the eighth embodiment. 10 is a circuit diagram of a feedback circuit used in Embodiment 9. FIG. It is a perspective view of Embodiment 10. FIG. It is a circuit diagram of a conventional example. It is a timing chart for operation explanation of a conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Filter circuit 2 Rectifier circuit 3 Chopper circuit 4 Inverter circuit 5 Feedback circuit 6 Adder 7 Pulse signal generator 8 Oscillator 9 Driver circuit 10 Chopper control circuit 11 Pulse control circuit 12 Preheating start control circuit LA Discharge lamps Q1, Q2 Switching element Vstr Control signal OP-out Feedback signal

Claims (10)

An inverter circuit connected to the output of the DC power supply; an LC resonance circuit connected to the output of the inverter circuit; a discharge lamp connected in parallel to the capacitor of the LC resonance circuit; The frequency of the oscillation signal is brought close to and away from the resonance frequency of the LC resonance circuit according to the level of the level of the frequency modulation signal to be input and the driver circuit to be turned off, and the operation timing of the driver circuit is controlled by the oscillation signal. The difference between the signal level of the detected output corresponding to the output of the discharge lamp and the target value, and the difference between the oscillator to be applied, the pulse signal generator for generating the control signal in which the pulse part is superimposed on the voltage of the non-pulse part A feedback circuit having a comparator for generating a feedback signal for correcting the oscillation frequency at a signal level according to An adder for supplying the signal obtained by adding the signal level of the control signal and the signal level of the feedback signal of the feedback circuit to the oscillator as the frequency modulation signal, and the pulse signal generator. A pulse control circuit for controlling a pulse signal waveform, and the pulse control circuit controls the pulse signal generator so that the amplitude of the pulse part gradually decreases after the start-up lighting of the discharge lamp, and the feedback circuit Performs a discharge control so that the output of the discharge lamp is constant. The discharge lamp lighting device according to claim 1, wherein the feedback circuit operates when pre-heating of the filament of the discharge lamp is completed. A lighting operation circuit that detects lighting by detecting the output of the discharge lamp, and the pulse control circuit performs a control operation to gradually reduce the amplitude of the pulse portion in synchronization with the output of the lighting determination signal of the lighting determination circuit The discharge lamp lighting device according to claim 1, wherein: A lighting determination circuit for detecting lighting by detecting an output of the discharge lamp is provided, and the feedback circuit starts operation after the lighting determination circuit determines lighting at the start of the discharge lamp. The discharge lamp lighting device according to claim 1. A lighting determination circuit that detects lighting by detecting the output of the discharge lamp, and the pulse control circuit outputs the lighting determination signal at the same time that the lighting determination circuit outputs the amplitude of the pulse section or the area per unit time. 2. The discharge lamp lighting device according to claim 1, wherein the control operation is started by reducing the amplitude and then gradually decreasing the amplitude of the pulse portion. A lighting determination circuit for detecting lighting by detecting an output of the discharge lamp; and a delay circuit for inputting a lighting detection signal from the lighting determination circuit and delaying and outputting the signal, and the pulse control circuit includes a delay circuit. 2. The discharge lamp lighting device according to claim 1, wherein when a lighting detection signal is output from the control unit, the amplitude of the pulse portion is reduced to start the control operation. The discharge lamp lighting device according to claim 3, wherein the pulse control circuit varies a time during which the amplitude of the pulse portion is decreased to make the start-up period of the discharge lamp constant. Before SL lighting determining circuit comprises a low-pass filter circuit for removing high-frequency component of the output detection signal of the feedback circuit, the cutoff frequency of the low pass filter circuit with less frequency of the pulse signal, the lighting determination timing The discharge lamp lighting device according to any one of claims 3 to 7, wherein the operation is performed immediately before application of a pulse voltage to the discharge lamp in synchronization with the operation of the pulse signal generator. The feedback circuit includes a low-pass filter circuit having a sufficient attenuation rate with respect to a commercial power supply frequency, and a circuit that bypasses the low-pass filter circuit, and a signal that bypasses the low-pass filter circuit at start-up Is a comparison value of feedback input to the comparator, and when the variable control of the amplitude of the pulse part by the pulse control circuit is completed, a signal that has passed through the low-pass filter circuit is used as a comparison value of feedback. The discharge lamp lighting device according to any one of claims 1 to 8. A lighting fixture comprising the discharge lamp lighting device according to claim 1.

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