JP2009289555A - Discharge lamp lighting device, and luminaire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device capable of preventing striation and flickering of light without performing complicated control while avoiding a cataphoresis phenomenon. <P>SOLUTION: An inverter control part 73 operates an inverter circuit 52 at random to change a ripple of an envelope of a lamp current IL of a fluorescent lamp 15 without periodicity. Striation and flickering of light can be prevented without performing complicated control such as changing the direction of a DC voltage or modulating the DC voltage while avoiding the cataphoresis phenomenon without applying the DC voltage to the fluorescent lamp 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device having an inverter circuit for lighting a discharge lamp by converting a DC voltage into a high frequency voltage, and a lighting fixture including the same.

  Conventionally, this type of discharge lamp lighting device includes an inverter circuit that turns on the discharge lamp by converting a DC voltage into a high-frequency voltage, an LC resonance circuit connected between the inverter circuit and the discharge lamp, etc. And. The inverter circuit includes, for example, a half-bridge type having a pair of switching elements, and performs switching operation by duty-controlling the switching elements, and applies a high-frequency voltage of a predetermined frequency to the discharge lamp via the resonance circuit. Is possible.

  In such a discharge lamp lighting device, for example, assuming that the operating frequency of the inverter circuit is constant, a discharge lamp in which an inert gas having a large atomic weight, such as argon, is sealed, appears on the tube wall and moves along the tube. A so-called striation occurs. Since this striation gives an unpleasant feeling such as flickering of light, for example, the on-duty of the paired switching elements is set asymmetrically, and a direct current bias is applied to the discharge lamp, so that the striation on the visual angle cannot be recognized. Such a configuration is known (for example, see Patent Document 1).

In addition, in a discharge lamp lighting device that performs dimming control of a discharge lamp according to a dimming signal from the outside, for example, when deeply dimming a high-frequency discharge lamp, the envelope of the lamp current flowing through the discharge lamp is Despite being flat, the light may flicker. In order to reduce such flickering of light, a configuration is known in which the operating frequency of an inverter is periodically modulated (see, for example, Patent Document 2).
JP-A-6-283286 (page 3-4, FIG. 1) JP-A-8-264295 (page 4-5, FIG. 1)

  However, in the discharge lamp lighting device described in Patent Document 1 described above, there is a possibility that a reduction in brightness due to mercury bias, a so-called catalysis phenomenon may occur due to the applied DC bias.

  Therefore, in order to avoid strata and flickering light while avoiding such cataphoresis phenomenon, it is necessary to change the direction of the DC bias, modulate the DC bias, or turn on the light by frequency control. There is a problem that the lighting control of the lamp becomes complicated.

  In addition, when a DC bias is applied, there is a problem that it becomes difficult to detect the end of the lamp life of the discharge lamp.

  The present invention has been made in view of these points, and provides a discharge lamp lighting device capable of preventing striation and light flicker without complicated control while avoiding a catalysis phenomenon, and a lighting fixture including the same. The purpose is to do.

  The discharge lamp lighting device according to claim 1 is an inverter circuit for lighting a discharge lamp by converting a DC voltage into a high-frequency voltage; the inverter circuit has no periodicity and an envelope ripple of a lamp current of the discharge lamp And a control means that operates to change.

  The discharge lamp is preferably a low-pressure mercury discharge lamp such as a fluorescent lamp, but is not limited thereto.

  As the inverter circuit, for example, a half bridge type including a pair of switching elements is used, but the inverter circuit is not limited thereto.

  The control means can employ, for example, a PWM changing method in which the operating frequency of the inverter circuit is intermittently turned on and off at a frequency lower or higher than a preset high-frequency voltage frequency.

  The predetermined period is, for example, every cycle of the operating frequency of the inverter circuit or every several cycles.

  A discharge lamp lighting device according to a second aspect of the present invention is the discharge lamp lighting device according to the first aspect, further comprising a current detection means for detecting a lamp current flowing through the discharge lamp, and the control means detects the lamp current detected by the current detection means. A target value for operating the inverter circuit at an operating frequency corresponding to the frequency is set so as not to have periodicity, and the inverter circuit is controlled so as to approach the target value.

  The current detection means detects, for example, a lamp current that substantially flows in the discharge lamp.

  A discharge lamp lighting device according to a third aspect is the discharge lamp lighting device according to the second aspect, wherein the control means uses a random number for setting a target value that is varied so as not to have periodicity.

  A discharge lamp lighting device according to a fourth aspect of the present invention is the discharge lamp lighting device according to the first aspect, further comprising a current detection means for detecting a lamp current flowing through the discharge lamp, and the control means is a lamp current detected by the current detection means. Set a target value for operating the inverter circuit at an operating frequency according to the control frequency, and control the inverter circuit by changing the gain of the inverter circuit set so as to approach this target value so as not to have periodicity Is.

  The discharge lamp lighting device according to claim 5 is the discharge lamp lighting device according to claim 4, wherein the control means is a target for flattening the envelope of the lamp current detected by the current detection means with respect to the gain of the inverter circuit. The value is larger than the gain.

  The lighting fixture according to claim 6 comprises: a fixture main body to which the discharge lamp is attached; and the discharge lamp lighting device according to any one of claims 1 to 5 that controls lighting of the discharge lamp.

  According to the discharge lamp lighting device of claim 1, the control means applies the DC voltage by operating the inverter circuit so that the ripple of the envelope of the lamp current of the discharge lamp does not have periodicity and changes. Without causing cataphoresis, it is possible to prevent striation and flickering without complicated control such as changing the direction of the DC voltage or modulating the DC voltage.

  According to the discharge lamp lighting device according to claim 2, in addition to the effect of the discharge lamp lighting device according to claim 1, the control means operates the inverter circuit at the operating frequency corresponding to the lamp current detected by the current detection means. The target value to be changed is set so as not to have periodicity, and the inverter circuit is controlled so as to be close to the target value. It can be easily operated so that the ripple of the current envelope changes.

  According to the discharge lamp lighting device according to claim 3, in addition to the effect of the discharge lamp lighting device according to claim 2, the control means uses a random number for setting the target value to be varied so as not to have periodicity. Thus, the target value can be easily changed.

  According to the discharge lamp lighting device according to claim 4, in addition to the effect of the discharge lamp lighting device according to claim 1, the control means operates the inverter circuit at an operation frequency corresponding to the lamp current detected by the current detection means. By setting the target value to be set to be close to this target value, the inverter circuit is controlled by changing the gain of the inverter circuit so that it does not have periodicity, and thus the inverter circuit is made periodic. It can be easily operated so that the ripple of the envelope of the lamp current of the discharge lamp changes.

  According to the discharge lamp lighting device of the fifth aspect, in addition to the effect of the discharge lamp lighting device according to the fourth aspect, the control means provides the envelope of the lamp current detected by the current detection means with the gain of the inverter circuit. By making the value larger than the target gain for flattening, a gain for operating the inverter circuit so that the ripple of the envelope of the lamp current of the discharge lamp does not have periodicity can be easily obtained. be able to.

  According to the lighting fixture of Claim 6, each effect can be show | played by providing the discharge lamp lighting device as described in any one of Claim 1 thru | or 5.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  1 to 5 show a first embodiment, FIG. 1 is a circuit diagram showing a discharge lamp lighting device, FIG. 2 is an explanatory diagram schematically showing the main part of the discharge lamp lighting device, and FIG. 3 is a discharge lamp. FIG. 4 is a perspective view showing a lighting fixture equipped with a lighting device, FIG. 4 is a graph showing the operation of the power supply unit of the discharge lamp lighting device, and FIG. 5 is a graph showing the lamp current of the discharge lamp lighting device.

  As shown in FIG. 3, the lighting fixture 11 has a fixture main body 12, a reflective surface 13 is formed on the lower surface of the fixture main body 12, and lamp sockets 14, 14, a straight tube type fluorescent lamp 15 as a discharge lamp is electrically and mechanically attached between the lamp sockets 14 and 14. Further, a discharge lamp lighting device 16 (hereinafter simply referred to as a lighting device 16) shown in FIG.

  In the fluorescent lamp 15, filaments FLa and FLb, which are electrodes, are sealed at both ends of a straight tube bulb B.

  The bulb B is a glass tube having a tube diameter of, for example, 25.5 mm, that is, T8 type or less, and a three-wavelength light emitting phosphor (not shown) is coated on the inner surface. Further, in the bulb B, a mixed gas of mercury and a rare gas such as argon and krypton is sealed as a discharge gas.

  As shown in FIG. 1, the lighting device 16 includes an inverter circuit 52 connected to a filter unit 50 and a power source unit 51 that rectifies and smoothes a commercial AC power source e, and an output terminal of the inverter circuit 52 includes a resonance circuit 53. The filaments FLa and FLb of the fluorescent lamp 15 are connected via the. In addition, a preheating circuit 55 for the filaments FLa and FLb of the fluorescent lamp 15 is connected to a connection portion between the inverter circuit 52 and the resonance circuit 53. Further, the power supply unit 51, the inverter circuit 52, and the preheating circuit 55 are connected to an MPU 56 that is a circuit control means as a control device (processing device), and the MPU 56 is supplied with power from the control power supply unit 57. The MPU 56 is connected to a dimming signal unit 58 that outputs a dimming signal DIM according to an external operation or the like. The filter unit 50, the power source unit 51, the inverter circuit 52, the resonance circuit 53, the preheating circuit 55, and the control power source unit 57 constitute a main circuit MC that operates the fluorescent lamp 15.

  The filter unit 50 includes a common mode transformer Tr connected to the commercial AC power source e and a capacitor C1 that cuts off a high frequency component connected to the common mode transformer Tr. The capacitor C1 side is connected to the power source unit 51. Yes.

  The power supply unit 51 is a step-up chopper power supply having a so-called critical mode power factor correction (PFC) function that matches the phase of the input current I0 and the input voltage V0, and a full-wave rectifier REC1 is connected to the filter unit 50 side. A boost chopper circuit 59 is connected to the output side of the full-wave rectifying element REC1. The boost chopper circuit 59 is connected to the output side of the full-wave rectifier element REC1 with a series circuit of a chopper choke L1 as a boosting transformer and a reverse blocking diode D1 between the inverter circuit 52 and the output circuit. A first switching element as a switching element, that is, a field effect transistor (FET) Q1, which is a chopping switching element, is connected in parallel to the connection point between the chopper choke L1 and the anode of the diode D1, and the cathode of the diode D1 The electrolytic capacitor C2, which is a smoothing capacitor, is connected in parallel to the connection point between the inverter circuit 52 and the inverter circuit 52.

  The chopper choke L1 has a primary winding L1a and a secondary winding L1b, and the primary winding L1a is connected between the output side of the full-wave rectifying element REC1 and the anode of the diode D1, and the secondary winding L1a One end of the winding L1b is connected to the ground potential, and the other end is connected to the MPU 56 via the detection resistor R1.

  In the field effect transistor Q1, the drain terminal is connected to the connection point between the chopper choke L1 and the anode of the diode D1, the resistance R2 is connected to the source terminal, and the gate terminal that is the control terminal is connected to the MPU 56. The MPU 56 performs switching driving based on the choke current flowing through the chopper choke L1 and the switching current IQ flowing through the field effect transistor Q1.

  The inverter circuit 52 is a so-called half-bridge type in which field effect transistors Q2 and Q3, which are inverter switching elements as second switching elements, are connected in series to the power supply unit 51.

  The field effect transistors Q2 and Q3 have their gate terminals as control terminals connected to the MPU 56 via a high side driver 65 as a driver unit, and ON / OFF is controlled by a signal supplied from the high side driver 65.

  The high side driver 65 alternately turns on / off the field effect transistors Q2 and Q3 at a frequency of about several tens of kHz to 200 kHz in accordance with the dimming PWM signal P supplied from the MPU 56 (switching driving). A predetermined high-frequency alternating current is generated between the drain and source of the field effect transistor Q3.

  In the resonance circuit 53, a resonance capacitor C4 is connected in parallel between both ends of the field effect transistor Q3 via a capacitor C3 that cuts off a DC component and a resonance winding (resonance inductor) L2 in series.

  The preheating circuit 55 includes a series circuit of a preheating transformer L3, a capacitor C5, a field effect transistor Q4 as a preheating switching element, and a current detection resistor R3, and a connection point between the capacitor C5 and the field effect transistor Q4 and a field effect. A diode D2 is connected between the source terminal of the transistor Q2.

  In the preheating transformer L3, the primary winding L3a, the first secondary winding L3b and the second secondary winding L3c are arranged to face each other, and the primary winding L3a is a connection point between the field effect transistors Q2 and Q3. And the resonance capacitor C4, and the secondary windings L3b and L3c are connected to the filaments FLa and FLb of the fluorescent lamp 15 via the capacitors C6 and C7, respectively.

  In the field effect transistor Q4, a gate terminal as a control terminal is connected to the MPU 56, and switching control is performed by a preheating PWM signal PP supplied from the MPU 56.

  The MPU 56 is a so-called microcomputer or the like that performs digital processing, and has a ROM, a RAM, an I / O port that is an interface, a clock generation unit that generates an operation clock, etc. , A state detector 71 as a current detector for detecting the lighting state of the fluorescent lamp, a chopper controller 72 for controlling the boost chopper circuit 59, an inverter controller 73 as a controller for controlling the high side driver 65, preheating For example, the state detection unit 71, the chopper control unit 72, the inverter control unit 73, and the preheating circuit control unit 74 are integrated with each other by sharing the software processing part. It has become.

  The state detection unit 71 detects the discharge current, that is, the lamp current IL, and the discharge voltage, that is, the lamp voltage VL, at timings synchronized with the peak phase, respectively, and converts them into digital frequency data corresponding to the lamp current IL and the lamp voltage VL. It has the function of an A / D converter which is an arithmetic means, and outputs the A / D converted lamp current IL and lamp voltage VL to the inverter control unit 73 or the preheating circuit control unit 74.

  The chopper control unit 72 generates a switching pulse SP for switching the field effect transistor Q1 for PFC control of the power supply unit 51, and adjusts the phase of the input voltage V0 and the input current I0 to improve the power factor. It is an improvement department.

  The inverter control unit 73 functions as a signal generation unit, that is, a dimming signal generation unit that generates the PWM signal P for controlling the operation of the field effect transistors Q2 and Q3 of the inverter circuit 52 based on the operation state detected by the state detection unit 71. Is a software part.

Here, as schematically shown in FIG. 2, the inverter control unit 73 includes a target value setting unit 81 that sets a set target value IT0 of the lamp current IL according to the lamp voltage VL, the dimming signal DIM, and the like, and a random number A random number generator 82 for generating R, and an adder 83 for adding the set target value IT0 set by the target value setting unit 81 and the random number R generated by the random number generator 82 and outputting the target value IT1 a subtracter 84 for calculating a difference delta ₁ with the lamp current IL detected by the adder output target value by 83 IT1 and state detection unit 71, based on the difference delta ₁ output from the subtracter 84 And an amplifier 85 for setting the PWM signal P corresponding to the operating frequency f for obtaining the gain G corresponding to the difference Δ ₁ . The high side driver 65 is driven by the PWM signal P output from the amplifier 85 so as to operate the inverter circuit 52 at the operating frequency f.

  The random number generation unit 82 can arbitrarily generate a random number R having no periodicity based on, for example, a random number sequence or a predetermined program. At this time, the random number to be generated has an upper limit and a lower limit, respectively, and is controlled by the average value. Any random number distribution can be used as the random number. In addition, the random number generator 82 can be switched, for example, between generating a random number R according to the dimming signal DIM and not generating (operating) the random number R. For example, when the dimming signal DIM is set to a predetermined dimming level or less, in this embodiment, when the dimming level is set to a predetermined dimming level of 60% or less when the fluorescent lamp 15 is fully lit, random numbers are generated. The unit 82 is configured to generate a random number R and arbitrarily set an upper limit and a lower limit of the random number R according to the dimming degree set by the dimming signal DIM.

  The adder 83 adds the random number R generated by the random number generator 82 to the set target value IT0 so that the target value IT1 operates at the original operating frequency corresponding to the lamp current IL. It distorts against the required target value. Therefore, the operation of the inverter circuit 52 is controlled by the inverter control unit 73, so that the lamp current IL is randomly distorted with respect to the target lamp current. That is, the distortion rate of the lamp current IL with respect to the target lamp current is such that the upper and lower limits of the random number R in the random number generator 82 are arbitrarily set according to the dimming degree set by the dimming signal DIM. It can be arbitrarily set according to the dimming degree.

  Further, the inverter control unit 73 sets the duty ratio of the field effect transistors Q2 and Q3 of the inverter circuit 52 to approximately 1: 1, and the voltage output from the inverter circuit 52 has substantially equal positive and negative peak values in one cycle. To be.

  In the ROM, various programs executed by the respective units of the MPU 56 are stored in advance.

  In the RAM, various digital values detected by the state detection unit 71 and the like are stored in areas assigned to them.

  The preheating circuit control unit 74 controls the switching of the field effect transistor Q4 of the preheating circuit 55, and is a preheating state detection unit that detects the preheating current IP of the preheating circuit 55. While monitoring, for example, an optimal preheating condition, that is, a target value is set so as to follow a change in at least one of the lamp current IL and the lamp voltage VL detected by the state detection unit 71 so that the preheating current IP approaches the target value. In addition, a preheating PWM signal PP to be supplied to the gate terminal of the field effect transistor Q4 of the preheating circuit 55 is generated.

The control power supply unit 57 is a part that supplies power for driving the control circuit CC that drives the fluorescent lamp 15 by controlling the MPU 56 and the main circuit MC. For example, the control power supply unit 57 supplies 3.3V or 1.8V from a power supply voltage of 5V. This is a portion that generates a so-called V _DD .

  The dimming signal unit 58 includes a dimming signal unit 91 for outputting a signal corresponding to the dimming signal DIM, and a full-wave rectification of the signal output from the dimming signal unit 91 as the dimming signal DIM. And a full-wave rectifying element REC2 output to the inverter control unit 73.

  Next, the operation of the first embodiment will be described.

  When the field effect transistor Q1 is turned on by a starting circuit (not shown) or the like, a linearly increasing current flows through the chopper choke L1 (diode D1), so that the choke current I flows through the secondary winding L1b of the chopper choke L1. Flows and electromagnetic energy is accumulated in the chopper choke L1. At the same time, when a voltage generated by the resistor R2 due to the switching current IQ when the field effect transistor Q1 is turned on is input to the MPU 56, an off switching pulse SP is supplied from the chopper controller 72 to the gate terminal of the field effect transistor Q1. When the effect transistor Q1 is turned off, the electromagnetic energy accumulated in the chopper choke L1 is released, and a linearly decreasing current flows through the chopper choke L1 (diode D1).

  By repeating this operation, as shown in FIG. 4, an output current I1 is formed by using the waveform of the input voltage V0, that is, the reference waveform SW, which is a sine waveform subjected to full-wave rectification, as an envelope.

  The output voltage V1 generated by the power supply unit 51 is generated by switching the field effect transistors Q2 and Q3 of the inverter circuit 52 on and off with the high-side driver 65 at a predetermined frequency and a predetermined on-duty. Converted to voltage.

  By this high frequency AC voltage, the resonance circuit 53 resonates and a resonance current flows, and the field effect transistor Q4 is switched by the preheating PWM signal PP having a predetermined frequency generated by the preheating circuit control unit 74. A preheating current IP flows through the secondary windings L3b and L3c of the preheating transformer L3 to preheat the filaments FLa and FLb of the fluorescent lamp 15.

  A predetermined starting voltage is applied between the filaments FLa and FLb by preheating the filaments FLa and FLb, the fluorescent lamp 15 is turned on (started), and the fluorescent lamp 15 is steadily lit.

  At this time, the lighting device 16 performs feedback control based on the lamp current IL detected by the state detection unit 71 so that the lamp current IL becomes a predetermined target value IT1.

  When dimming the fluorescent lamp 15 lit as described above, the PWM signal P is input from the inverter control unit 73 to the high side driver 65 of the lighting device 16 to vary the drive frequency of the inverter circuit 52. By increasing or decreasing the drive frequency of the inverter circuit 52, the high frequency power from the inverter circuit 52 is suppressed or increased, the lamp current IL is suppressed or increased, and the fluorescent lamp 15 is dimmed.

  The drive frequency of the inverter circuit 52, that is, the frequency of the PWM signal P is based on the dimming signal DIM output from the dimming signal unit 58 and the lamp current IL detected by the state detection unit 71 in the inverter control unit 73, for example. Is set.

  These controls are switched in accordance with the dimming degree set by the dimming signal DIM.

For example, when the dimming level is set to be greater than 60% by the dimming signal DIM, the random number generation unit 82 does not operate, and the inverter control unit 73 sets the target value according to the lamp voltage VL and the dimming signal DIM. setting the set target value IT0 of the lamp current IL by the setting unit 81, it becomes a target value IT1 is the set target value IT0, and the target value IT1, the difference delta ₁ with the lamp current IL detected by the state detection unit 71 Based on the difference Δ ₁ calculated by the subtractor 84, the amplifier 85 sets the PWM signal P corresponding to the operating frequency f for obtaining the gain G corresponding to the difference Δ ₁ .

On the other hand, when the dimming level is set to 60% or less by the dimming signal DIM, the inverter control unit 73 sets the lamp current IL by the target value setting unit 81 in accordance with the lamp voltage VL and the dimming signal DIM. A target value IT0 is set, and the set target value IT0 and the random number R generated by the random number generator 82 are added by an adder 83 to obtain a target value IT1, which is detected by the target value IT1 and the state detector 71. the difference delta ₁ with the lamp current IL is calculated by the subtractor 84, based on the difference delta _1, in the amplifier 85 a PWM signal P corresponding to the operating frequency f for obtaining a gain G corresponding to the difference delta ₁ Set.

  The frequency control by the PWM signal P is performed every cycle of the operating frequency of the inverter circuit 52 or every several cycles within a predetermined period, and the lighting state of the fluorescent lamp 15 is immediately reflected in the frequency of the PWM signal P. .

  In the preheating circuit 55, the preheating current IP approaches the target value set by the preheating circuit control unit 74 so as to follow the lamp current IL, the lamp voltage VL, or the ambient temperature change detected by the state detection unit 71. The field effect transistor Q4 is switched by the preheating PWM signal PP generated as described above, thereby optimizing the preheating amount during lighting that varies depending on the type of the fluorescent lamp 15 and variations in the manufacturing process.

  As described above, for example, as shown in FIG. 5, the inverter control unit 73 does not have periodicity so that the ripple of the envelope (envelope) of the lamp current IL of the fluorescent lamp 15 changes every predetermined cycle. Random operation of the inverter circuit 52 at a different operating frequency, in other words, an unnatural operating frequency fluctuation having a certain periodicity, and a natural randomly changing operating frequency (a stable operation in which the lamp current IL is intentionally naturally distorted) Lighting operation), avoiding the catalysis phenomenon without applying a DC voltage (DC bias) to the fluorescent lamp 15, while performing complex control such as changing the direction of the DC voltage or modulating the DC voltage. It is possible to prevent striation and light flickering without doing so.

  Specifically, the inverter control unit 73 sets the target value IT1 for operating the inverter circuit 52 at an operating frequency corresponding to the lamp current IL detected by the state detection unit 71 at predetermined intervals so as not to have periodicity. By controlling the inverter circuit 52 so as to be close to the target value IT1, the inverter circuit 52 can be easily operated at a different operating frequency for each predetermined period without having periodicity. .

  In particular, the fluorescent lamp 15 used exclusively for high frequency is likely to cause light flicker, and the fluorescent lamp 15 having a tube diameter of the bulb B of T8 or less is likely to cause a catalysis phenomenon or striation. By setting the inverter circuit 52 to operate randomly as described above, even if the fluorescent lamp 15 is used exclusively for high frequency and is relatively thin, the catalysis phenomenon can be performed without requiring complicated control. It can reliably prevent striations and light flickering.

  Further, by using the random number R for the setting of the target value IT1 to be varied so that the inverter control unit 73 does not have periodicity, the target value IT1 can be easily varied randomly. In particular, in the random number generator 82 of the MPU 56 which is a digital circuit, a pseudo random number can be easily generated compared to an analog circuit by using a program or the like.

  Further, the random number generator 82 can set the upper limit and lower limit of the random number and control the average value thereof to prevent the fluorescent lamp 15 from becoming unsatisfactory or damaged.

  Then, the inverter control unit 73 controls the inverter circuit 52 so that the positive and negative of the peak value of the output voltage from the inverter circuit 52 in one cycle of the operating frequency of the inverter circuit 52 becomes substantially equal, so that the fluorescent lamp 15 A direct voltage is not applied, and a cataphoresis phenomenon of the fluorescent lamp 15 due to the direct voltage, that is, a phenomenon such that one end side of the straight fluorescent lamp 15 becomes bright and the other end side becomes dark due to the bias of mercury can be prevented.

  Further, since no DC voltage is applied to the fluorescent lamp 15, the end of life can be detected via the lamp voltage VL of the fluorescent lamp 15.

  Furthermore, since the above configuration does not require complicated control such as changing the direction of the DC voltage or modulating the DC voltage, the configuration and program of the MPU 56 can be simplified, downsizing and reduction in manufacturing cost. Etc. are also possible.

  Then, the inverter control unit 73 sets the duty ratio of the field effect transistors Q2 and Q3 of the inverter circuit 52 to approximately 1: 1, and the voltage output from the inverter circuit 52 is approximately equal to the positive and negative peak values of one cycle. By doing so, it is possible to reliably suppress the DC voltage from being applied to the fluorescent lamp 15.

  In addition, since the inverter control unit 73 controls the random number generator 82 to generate the random number R and operate the inverter circuit 52 at random when the dimming signal DIM is set to a predetermined dimming degree, particularly during dimming. Cataphoresis phenomenon, striation, and flickering of light that occur easily can be reliably prevented even during dimming.

  Furthermore, by varying the distortion rate of the lamp current IL according to the dimming level set by the dimming signal DIM, even when performing deep dimming, it is possible to reliably prevent cataphoresis, striation, and light flickering. it can.

  By operating the inverter circuit 52 at random, noise generated by switching the field effect transistors Q2 and Q3 of the inverter circuit 52 does not have periodicity and is not concentrated on a specific frequency but distributed over a wide frequency band. As a result, auditory noise can be reduced.

  Next, FIG. 6 shows a second embodiment, and FIG. 6 is an explanatory view schematically showing a main part of the discharge lamp lighting device. In addition, about the structure and effect | action similar to the said 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In the second embodiment, the gain G set by the inverter control unit 73 is randomly changed in the first embodiment.

That is, for example, when the dimming signal is set to 60% or less by the dimming signal DIM, the inverter control unit 73 sets the set target value IT0 set by the target value setting unit 81 and the lamp detected by the state detection unit 71. A difference Δ ₂ with respect to the current IL is calculated by the subtractor 84, and the target PWM signal P 0 corresponding to the target operating frequency f 0 for obtaining the target gain G 0 corresponding to the difference Δ ₂ is generated by the random number generator 82. The random number R is added by the adder 93 so that the PWM signal P, which is a distorted target value with respect to the target PWM signal P0, is output, so that it differs from the target operating frequency f0 via the high side driver 65. The inverter circuit 52 is configured to randomly operate at the operating frequency f.

  Here, the random number R generated by the random number generator 82 is PWM for obtaining a gain G larger than the target gain G0 of the inverter circuit 52 for flattening the envelope of the lamp current IL detected by the state detector 71. The signal P is set to be obtained.

  As a result, the inverter control unit 73 operates the inverter circuit 52 at random so that the ripple of the envelope of the lamp current IL of the fluorescent lamp 15 does not have periodicity, and the like, as in the first embodiment. By having this configuration, the same operational effects as those of the first embodiment can be obtained.

  Specifically, the inverter control unit 73 sets a set target value IT0 for operating the inverter circuit 52 at an operating frequency corresponding to the lamp current IL detected by the state detecting unit 71, and sets the set target value IT0. By controlling the inverter circuit 52 by randomly changing the PWM signal P so as to change the gain G of the inverter circuit 52 set so as to be close so as not to have periodicity, It can be easily operated so that the ripple of the envelope of the lamp current IL of the fluorescent lamp 15 changes.

  Further, the PWM signal P for the inverter control unit 73 to obtain the gain G of the inverter circuit 52 is larger than the target gain G0 for making the envelope of the lamp current IL detected by the state detection unit 71 flat. Thus, the gain G for operating the inverter circuit 52 at random can be easily obtained.

  In each of the above embodiments, the inverter control unit 73 detects, for example, a DC voltage applied to the fluorescent lamp 15, and sets the duty of the field effect transistors Q2 and Q3 so that the DC voltage becomes zero. Also good.

  Various circuits such as the filter unit 50, the power source unit 51, the resonance circuit 53, and the preheating circuit 55 are not limited to the above-described configuration.

  Furthermore, the lighting fixture 11 may not be dimmable by the dimming signal DIM.

It is a circuit diagram which shows the discharge lamp lighting device of the 1st Embodiment of this invention. It is explanatory drawing which shows typically the principal part of a discharge lamp lighting device same as the above. It is a perspective view which shows the lighting fixture provided with the discharge lamp lighting device same as the above. It is a graph which shows operation | movement of the power supply part of a discharge lamp lighting device same as the above. It is a graph which shows the lamp current of a discharge lamp lighting device same as the above. It is explanatory drawing which shows typically the principal part of the 2nd Embodiment of this invention.

Explanation of symbols

11 Lighting equipment
12 Instrument body
15 Fluorescent lamps as discharge lamps
16 Discharge lamp lighting device
52 Inverter circuit
71 State detection unit as current detection means
73 Inverter control unit as control means

Claims (6)

An inverter circuit for turning on a discharge lamp by converting a DC voltage into a high-frequency voltage;
Control means for operating the inverter circuit so that the ripple of the lamp current envelope of the discharge lamp does not have periodicity;
A discharge lamp lighting device comprising: Comprising current detection means for detecting a lamp current flowing in the discharge lamp;
The control means sets the target value for operating the inverter circuit at an operating frequency corresponding to the lamp current detected by the current detecting means so as not to have periodicity, and sets the target value close to the target value. The discharge lamp lighting device according to claim 1, wherein the circuit is controlled. The discharge lamp lighting device according to claim 2, wherein the control means uses a random number for setting a target value to be varied so as not to have periodicity. Comprising current detection means for detecting a lamp current flowing in the discharge lamp;
The control means sets a target value for operating the inverter circuit at an operating frequency corresponding to the lamp current detected by the current detection means, and has a periodicity for the gain of the inverter circuit set so as to be close to the target value. The discharge lamp lighting device according to claim 1, wherein the inverter circuit is controlled so as not to fluctuate. The discharge lamp lighting device according to claim 4, wherein the control means sets the gain of the inverter circuit to a value larger than a target gain for flattening the envelope of the lamp current detected by the current detection means. An instrument body to which a discharge lamp is attached;
A discharge lamp lighting device according to any one of claims 1 to 5, which controls lighting of the discharge lamp;
The lighting fixture characterized by comprising.

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