JP2009070581A - Discharge lamp lighting device and illumination apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can prevent a dying out and a flickering of a discharge lamp by rectifying a light control curve according to an ambient temperature. <P>SOLUTION: In the discharge lamp lighting device having a light adjustment control portion for changing an output of an inverter 3 according to a light adjustment signal, there is provided a light control curve rectifying means 62 which detects characteristics (for example, a discharging lamp voltage) for regulating a movement of a discharge lamp La which changes by an affect of a coldest point temperature of the discharge lamp La by a detecting circuit 8 and which, when a detected signal exceeds a predetermined reference value according to the light adjustment signal, rectifies the light control curve that is a change of a discharge lamp power according to the light adjustment signal. The light control curve rectifying means 62 makes smaller an inclination of the light control curve and rectifies to raise a lamp power when the coldest point temperature of the discharge lamp La is lower than that at room temperature and makes larger the inclination of the light control curve and rectified to lower the lamp power when the coldest point temperature of the discharge lamp La is higher than that at room temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device for lighting and dimming a discharge lamp with high-frequency power.

  Conventionally, there are the following means for preventing the turn-off and flickering at low temperatures even when the discharge lamp is turned on and dimmed and set to a sufficient dimming width.

  In Patent Document 1 (Japanese Patent Laid-Open No. 5-89992), temperature compensation means (diode) is provided as means for changing the inverter output, and the dimming level changes depending on the temperature characteristics of the temperature compensation means, thereby reducing the temperature. At times, the lamp output increases from room temperature, preventing the lights from going out.

In Patent Document 2 (Japanese Patent Laid-Open No. 5-283189), the lamp voltage is detected and compared with a reference voltage. When the lamp voltage is higher than the reference voltage, the lamp output is set so that the lamp voltage does not increase any more. By increasing the number, it disappears at low temperatures.
JP-A-5-89992 JP-A-5-283189

  In Patent Document 1 (Japanese Patent Laid-Open No. 5-89992), a lamp output is increased by changing a signal for determining an inverter frequency at a low temperature by temperature compensation means such as a diode or a thermistor to prevent the lamp from going out. It cannot be said that the coldest spot and the temperature of the temperature compensation means have a certain correlation. For example, when the temperature of the temperature compensation means inside the ballast is sufficiently high and the cooled lamp is turned on and dimmed (for example, when the lamp is replaced), the temperature compensation means does not operate effectively. In addition, the temperature compensation means inside the ballast is different between immediately after lighting and when sufficient time has elapsed since lighting, so even if the ambient temperature of the lamp is not low, the temperature compensating means malfunctions immediately after lighting, When the temperature is low and a sufficient time has elapsed after lighting, the temperature compensation means does not operate. As described above, even when a temperature compensation means such as a diode or a thermistor is used, the correlation between the temperature of the coldest point of the lamp and the temperature compensation means is not always constant. .

  In Patent Document 2 (Japanese Patent Laid-Open No. 5-283189), the lamp voltage is detected, and the lamp output is increased when the lamp voltage becomes higher than the reference voltage during dimming. In the case of light, the operation range of the dimmer becomes narrow. That is, there is a problem that the operation range of the dimmer changes depending on the ambient temperature of the lamp.

  The solid line in FIG. 14 shows the relationship between the dimming signal at normal temperature and the lamp power. The dimming signal is a PWM signal, and the dimming level is changed by changing its duty. The dimming signal duty: 0% is full output, the dimming signal duty: 85% is the dimming lower limit, and if the dimming signal duty further increases, the light is turned off. The dotted line in FIG. 14 shows the relationship between the dimming signal at low temperature and the lamp power. In this case, it is assumed that lamp power feedback is performed for easy understanding. Since the lamp voltage increases during dimming at low temperatures, the lamp voltage operates so as not to exceed the reference voltage, and the lamp power changes only in a narrower range than the original dimming signal as shown by the dotted line in FIG. is there.

  As described above, in the conventional example of Patent Document 2, the operation range of the dimmer changes depending on the lamp ambient temperature. For example, as shown in FIG. 14, the duty of the dimming signal is 0% to 85% at room temperature. However, the lamp power changes only when the duty of the dimming signal is in the range of 0% to 70% at a low temperature, which makes the user feel uncomfortable.

  Further, in the conventional example of Patent Document 2, since the lamp output is increased after detecting the rise of the lamp voltage before going out, even if the lamp ambient temperature is low before the lamp voltage rises, Does not increase the output. In general, from near the rated output to the middle of dimming, the lamp voltage is lower at low temperatures than at normal temperatures. Therefore, although the illuminance is lower at the low temperature than at the normal temperature, the lamp output is increased just before the extinction in the conventional example of Patent Document 2, so the illuminance from the vicinity of the rated output to the middle of the dimming remains low.

  The present invention has been made to solve the above-described problems, and defines the operation of a lamp that changes due to the influence of the coldest spot temperature of the lamp without using a temperature compensation means such as a diode or a thermistor. By detecting the characteristics of the lamp, the lamp will not turn off or flicker, and the dimming curve will be corrected to reduce the operating range of the dimmer even if the lamp ambient temperature (lamp coldest point temperature) changes. It is an object of the present invention to provide a discharge lamp lighting device without any problem. Further, it is intended to provide a discharge lamp lighting device capable of suppressing a decrease in illuminance at a low temperature by increasing the output even in the middle of dimming from the vicinity of the rated output instead of increasing the lamp output before extinction. Let it be an issue.

  In order to solve the above-described problem, the invention of claim 1 includes an inverter 3 including at least one switching element Q1, Q2 connected to an output terminal of a DC power source E, as shown in FIG. The load circuit 5 that allows the discharge lamp La to be connected to the output terminal of the inverter 3 via the resonance circuit 4, and characteristics that define the operation of the discharge lamp La that changes due to the influence of the coldest spot temperature of the discharge lamp La (for example, , A discharge circuit voltage), and a detection circuit 8 that outputs a detection signal, and a dimming control unit (microcomputer 6) that receives the dimming signal and changes the output of the inverter 3 according to the dimming signal. In the discharge lamp lighting device, the dimming control unit (microcomputer 6) is configured such that when the detection signal exceeds a predetermined reference value set according to the dimming signal, the discharge lamp power according to the dimming signal Dimming curve that is a change of The light control curve correcting means 62 is provided to correct the light control curve, and the light control curve correcting means 62 reduces the slope of the light control curve when the coldest spot temperature of the discharge lamp La is lower than the coldest spot temperature at room temperature. The lamp power is corrected in the direction to increase, and when the coldest spot temperature of the discharge lamp La is higher than the coldest temperature at room temperature, the lamp power is corrected by increasing the slope of the dimming curve. It is characterized by.

  According to a second aspect of the present invention, in the first aspect of the present invention, the dimming curve correction means 62 is configured so that the change width of the dimming signal in which the discharge lamp power changes even after correction is as shown in FIG. It is characterized by correcting the slope of the dimming curve so as to be the same.

  In the invention of claim 3, as shown in FIGS. 5 and 8, the characteristic defining the operation of the discharge lamp La detected in the dimming state is a direct current component of the discharge lamp voltage, and the detection signal is the discharge lamp. A value corresponding to a DC component of the voltage is detected.

  In the invention of claim 4, as shown in FIG. 7, the characteristic that defines the operation of the discharge lamp La is the starting voltage at which the discharge lamp La is lit, and the discharge lamp voltage is gradually increased from the pre-filament preheating to the starting time of the discharge lamp. And a value corresponding to the voltage at which the discharge lamp La starts is detected.

  In the invention of claim 5, as shown in FIGS. 8 to 12, the dimming control unit (microcomputer 6) intermittently adjusts the light from the rated output to the dimming lower limit in a short period that cannot be recognized by human eyes. The light is emitted, and the detection circuit detects a characteristic that defines the operation of the discharge lamp La during the period and outputs a detection signal.

  Invention of Claim 6 is a lighting fixture characterized by including the discharge lamp lighting device in any one of Claims 1-5, and the discharge lamp by which lighting operation is controlled by this discharge lamp lighting device. (FIG. 15).

  The “characteristics defining the operation of the discharge lamp that changes due to the influence of the coldest spot temperature of the discharge lamp” described in the claims generally means the discharge lamp voltage Vla, the discharge lamp current Ila, and the discharge lamp power Wla. And also includes a resonance current that is affected by a change in the discharge lamp current Ila. In addition, when these electrical characteristics are detected and a feedback operation is performed so as to obtain a desired value, the operating frequency of the inverter that controls the lamp output, the power supply voltage of the inverter, etc. It is included in the “characteristics that regulate the operation of the discharge lamp that varies depending on”. For example, when lamp current feedback is performed, the lamp current is constant even if the lamp coldest spot temperature changes, but the operating frequency of the inverter changes.

  The ambient temperature of the lamp can be accurately detected by detecting a factor that changes due to the influence of the above-mentioned lamp coldest spot temperature. The coldest spot of the lamp is a place where the discharge tube is coldest while the lamp is lit. Generally, the temperature at the coldest spot of the lamp has a great influence on the mercury vapor pressure inside the discharge tube. That is, the temperature at the coldest spot of the lamp disappears and becomes a factor governing the occurrence of flicker.

  According to the first aspect of the present invention, it is possible to more accurately detect that the ambient temperature of the lamp is lower than the normal temperature, and to avoid turning off and flickering, rather than using temperature compensation means such as a diode or a thermistor. Further, when the ambient temperature of the lamp is higher than normal temperature, the light can be further adjusted to a deeper level. In addition, the lamp output is not increased before extinction, but the output is increased during the dimming from the vicinity of the rated output, so that it is possible to suppress a decrease in illuminance at low temperatures.

  According to the invention of claim 2, even when correcting the dimming lower limit at a low temperature, the operating range of the dimmer is not narrowed, and the operating range of the dimmer is the same even if the lamp ambient temperature changes. Therefore, the user can use it without feeling uncomfortable.

  According to the invention of claim 3, by detecting the direct current component of the lamp voltage during dimming, it is possible to more accurately detect that the lamp ambient temperature is low in a wide dimming range.

  According to the invention of claim 4, since the light control lower limit can be corrected immediately after lighting, flickering and extinction immediately after lighting can be avoided.

  According to the invention of claim 5, since the lamp voltage or the like can be detected in the entire dimming range including the rated output, it is possible to surely avoid the extinction and to adjust the dimmer without narrowing the operation range. The light can be controlled.

(Embodiment 1)
FIG. 1 is a circuit diagram of a first embodiment of the present invention. The discharge lamp lighting device of the present embodiment includes a DC power supply E having a constant output voltage, an inverter 3 connected to the output terminal of the DC power supply E, a resonance circuit 4 connected to the output terminal of the inverter 3, and a discharge lamp La. Load circuit 5, a control circuit 1 that determines a switching operation of the inverter 3 in response to a control signal from the microcomputer 6, a dimmer 7 that outputs a dimming signal including a duty variable PWM signal, and a lamp voltage Vla And a microcomputer 6 that receives the dimming signal and the detection signal and outputs a control signal to the control circuit 1. The discharge lamp La is a lamp whose light output varies depending on the ambient temperature, for example, a hot cathode fluorescent lamp.

The DC power source E uses a step-up chopper, and the circuit of the step-up chopper includes an AC power source Vs, a diode bridge DB1, an inductor L2, a diode D1, a smoothing capacitor C3, a switching element Q3, as shown in the figure. And a control circuit 2. When this circuit is used, the range of the DC voltage V _DC is constant at a certain value of Vs (peak) ≦ V _DC . Here, Vs (peak) indicates the peak value of the AC power supply Vs. If the AC power supply is 100V, the value is about 282V for the AC power supply of about 141V and 200V. Although the DC voltage V _DC can be made constant or variable by the operation of the chopper circuit, in this embodiment, the DC voltage V _DC operates at a constant regardless of the lamp load.

The inverter 3 has a series circuit of switching elements Q1 and Q2 connected in parallel to the output of the DC power supply E, and a DC cut capacitor _CD is connected between the midpoint of the switching elements Q1 and Q2 and the inductor L1. The switching elements Q1 and Q2 are driven by the control circuit 1 so as to be alternately turned on and off at a high frequency. The control circuit 1 is an IC in which a variable frequency oscillator and a drive circuit are integrated. The switching frequency and on-duty of the switching elements Q1 and Q2 are varied according to a control signal from the microcomputer 6 to control lighting and dimming of the lamp. be able to.

  Hereinafter, the basic operation of this embodiment will be described. FIG. 2 shows changes in the operating frequency of the inverter 3 with respect to the dimming signal in the present embodiment. The solid line is the control characteristic when the lamp ambient temperature is normal temperature (25 ° C.), the alternate long and short dash line A is the control characteristic when the lamp ambient temperature is 0 ° C., and the dotted line B is the control characteristic when the lamp ambient temperature is 50 ° C. .

  FIG. 3 shows the change (dimming curve) of the lamp power with respect to the dimming signal in this embodiment. The solid line is the dimming curve when the lamp ambient temperature is room temperature (25 ° C.), and the alternate long and short dash line A is the dimming curve when driven at the inverter operating frequency (FIG. 2A) at the lamp ambient temperature of 0 ° C. Is a dimming curve when the lamp is driven at an inverter operating frequency (FIG. 2B) at a lamp ambient temperature of 50 ° C.

  FIG. 4 shows changes in the lamp voltage detection signal with respect to the dimming signal at lamp ambient temperatures of 0 ° C., 25 ° C., and 50 ° C. A thick line C is a reference voltage programmed in the microcomputer 6. Here, the lamp output changes when the duty of the dimming signal is in the range of 0% to 85%. In this embodiment, the lamp voltage is always detected, and the microcomputer 6 compares the value of the lamp voltage detection signal with respect to the dimming signal with the reference voltage. For this purpose, the microcomputer 6 includes a dimming signal / detection signal comparison table 61, and compares the level of the thick line C corresponding to the dimming signal with the level of the detection signal. According to the comparison result, the dimming curve correction means 62 corrects the operating frequency of the inverter 3 according to the dimming signal as shown in FIG.

  In FIG. 4, when the duty of the dimming signal is in the range of 0% to 70%, if the detection signal falls below the level of the thick line C, it is determined that the coldest spot temperature of the lamp is lower than that at room temperature. As indicated by the chain line A, the lamp output power is increased by lowering the operating frequency of the inverter 3 with respect to the dimming signal to prevent the light from going out. At the same time, since the change width (inclination) of the operating frequency of the inverter 3 with respect to the dimming signal is also changed, dimming can be performed without changing the dimming range as compared with normal temperature as shown in FIG.

  In FIG. 4, when the duty of the dimming signal is in the range of 70% to 85%, when the dimming signal falls below the level of the thick line C, it is determined that the lamp coldest spot temperature is higher than that at room temperature. As indicated by the dotted line B, the lamp output power can be reduced by increasing the operating frequency of the inverter 3 with respect to the dimming signal, and the dimming can be further deepened. Since the coldest spot temperature of the lamp is high, the lamp impedance is low, and it is possible to adjust the light to a deep level without causing extinction or flickering.

  When the lamp voltage detection signal exceeds the value of the thick line C, which is the reference voltage, during the dimming, the user can make a sudden change in light by gradually changing the dimming curve according to the degree of the excess. It is possible to correct the dimming curve without any sense of incongruity.

In the embodiment circuit of FIG. 1, the control signal of the microcomputer 6 is given to the control circuit 1. However, the control signal may be given to the control circuit 2 or to both the control circuits 1 and 2. In that case, instead of the inverter operating frequency shown in FIG. 2 or together with the inverter operating frequency, the inverter power supply voltage V _DC is variably controlled, so that the lamp power is changed according to the dimming signal as shown in FIG. What is necessary is just to change the control signal of the microcomputer 6 so that it may change like the dashed-dotted line A at the time, and the dotted line B at the time of high temperature. The same applies to the following embodiments.

(Embodiment 2)
FIG. 5 is a circuit diagram of the second embodiment of the present invention. The present embodiment is different from the previous embodiment in that, in addition to the lamp voltage detection circuit 8 that detects the AC component of the lamp voltage, a lamp DC voltage detection circuit 9 that detects the DC voltage component of the lamp voltage is further provided. These outputs are input to the microcomputer 6.

  FIG. 6 shows changes in the lamp DC voltage with respect to the dimming signal at lamp ambient temperatures of 0 ° C., 25 ° C., and 50 ° C. A dotted line D is a reference voltage programmed in the microcomputer 6.

  In general, the lamp DC voltage of a fluorescent lamp has a low lamp impedance in the vicinity of the rated output, so even if the lamp ambient temperature changes, there is almost no difference in the lamp DC voltage. However, since dimming increases the lamp impedance particularly at low temperatures, a difference in lamp DC voltage due to the ambient temperature of the lamp is significantly generated. Therefore, it is effective for detection at low temperature during dimming output.

  In the first embodiment, the AC component of the lamp voltage is detected, and the lamp voltage at the low temperature (0 ° C.) and the lamp voltage at the high temperature (50 ° C.) intersect each other during dimming as shown in FIG. For this reason, it is difficult to detect that the coldest spot temperature of the lamp is low when the duty of the dimming signal is 70% or more.

  Therefore, in this embodiment, when the duty of the dimming signal is in the range of 70% or more, the lamp DC voltage detection signal from the lamp DC voltage detection circuit 9 is compared with the reference voltage, and the lamp DC voltage detection signal is shown by the dotted line in FIG. When it becomes D or more, the dimming curve is changed in the direction of increasing the output to prevent the light from turning off. In the range where the duty of the dimming signal is 70% or less, the lamp voltage detection signal from the lamp voltage detection circuit 8 is compared with the reference voltage in the same manner as in the first embodiment, and the lamp voltage detection signal is less than the thick line C in FIG. If this happens, the dimming curve is changed in the direction of increasing output to prevent the light from turning off.

  Also in the present embodiment, as in the first embodiment, since the slope of the dimming curve is gently changed, the width of the dimming signal in which the lamp power changes at a low temperature is room temperature, as indicated by a dashed line A in FIG. The operation range of the dimmer 7 does not change depending on the ambient temperature.

  As described above, in the present embodiment, both the AC component and the DC component of the lamp voltage with respect to the duty of the dimming signal are detected, and the detection voltage in which the difference due to the coldest spot temperature of the lamp becomes clear according to the duty of the dimming signal Since the microcomputer 6 compares the reference voltage (AC component at high output and DC component at low output) with the microcomputer 6, it can detect that the ambient temperature of the lamp is low in a wide range of light control more accurately. Accordingly, the dimming curve can be changed in the direction of increasing the output to prevent the light from turning off.

  The specific circuit configurations of the lamp voltage detection circuit 8 and the lamp DC voltage detection circuit 9 are not limited to the illustrated embodiment. In short, the amplitude of the AC component of the lamp voltage, the DC component of the lamp voltage. Any configuration can be used as long as each can be detected.

(Embodiment 3)
FIG. 7 is an operation waveform diagram of Embodiment 3 of the present invention, and the circuit diagram of this embodiment is the same as FIG. FIG. 7 shows a lamp secondary voltage waveform at the start from the preceding preheating period. Here, the lamp secondary voltage is a no-load output voltage applied to both ends of the lamp in a state before the discharge lamp La is turned on. The characteristic point of this embodiment is that the operating frequency of the inverter 3 is swept from the filament pre-preheating time to the lamp starting time, the voltage at which the lamp is started is detected by the lamp voltage detecting circuit 8, and compared with the reference voltage inside the microcomputer 6. It is a point to do.

  Although the filament preheating circuit of the discharge lamp La is not particularly illustrated, a known capacitor preheating method, winding preheating method, or the like is used.

  After the preceding preheating period, the operation frequency of the inverter 3 is brought close to the no-load resonance frequency of the resonance circuit 4. A high voltage is applied to both ends of the lamp 5 as the frequency decreases. When the starting voltage is reached, the lamp 5 is turned on. As shown by the solid line and the dotted line in FIG. Thus, since the starting voltage varies depending on the lamp coldest spot temperature, the lamp coldest spot temperature can be detected by detecting the starting voltage.

  When the starting voltage is higher than the reference voltage set inside the microcomputer 6, it is judged that the lamp coldest spot temperature is low, and the microcomputer 6 causes the control circuit 1 to operate the inverter 3 as shown by the one-dot chain line A in FIG. A control signal is output so as to have a frequency. Thus, the light control curve is controlled as indicated by the one-dot chain line A in FIG.

  As described above, in the present embodiment, by detecting the starting voltage, the dimming lower limit can be corrected immediately after lighting, so that flickering and extinction immediately after lighting can be avoided. After starting the discharge lamp, Embodiments 1 and 2 or the following Embodiment 4 may be used in combination.

(Embodiment 4)
FIG. 8 is a circuit diagram of a fourth embodiment according to the present invention. The present embodiment is different from the first embodiment in that a lamp DC voltage detection circuit 9 is provided, and the microcomputer 6 periodically outputs a control signal whose lamp power becomes the dimming lower limit to the control circuit 1 in a pulsed manner. is there.

  FIG. 9 shows a lamp current waveform at the time of Full output in this embodiment. FIG. 10 shows a ramp voltage waveform at the time of Full output in this embodiment.

  The frequency f1 is an inverter operating frequency near the rated output. The frequency f2 is a frequency near the dimming lower limit. Since the period of f2 is about several milliseconds and the alternating frequency for switching between f1 and f2 is also several kHz or more, a change in light is not perceived by human eyes. That is, the characteristic point of this embodiment is that the light is adjusted in a short period (several milliseconds) that cannot be detected by human eyes, and the lamp voltage DC component at that time is detected to detect the coldest spot of the lamp. It is a point to detect temperature.

  11 and 12 show the lamp DC voltage at normal temperature and the lamp DC voltage at low temperature, respectively. Since the frequency f1 is near the rated output, there is not much difference between normal temperature and low temperature as shown in FIG. Since the frequency f2 is a frequency near the lower limit of dimming, there is a difference in lamp DC voltage between normal temperature and low temperature. Accordingly, it is possible to detect that the lamp coldest spot temperature is low by detecting the lamp DC voltage in the period of the frequency f2 by the lamp DC voltage detection circuit 9 and comparing it with the reference voltage by the microcomputer 6.

  Depending on the lamp, the temperature characteristic of the lamp voltage (AC component) near the rated output may be as shown in FIG. The lamp voltage (alternating current component) decreases at substantially the same level at both low and high temperatures compared to normal temperature. In this case, the lamp coldest spot temperature cannot be detected even if the lamp voltage (alternating current component) is detected in the vicinity of the rated output.

  In this embodiment, since the lamp DC voltage near the dimming lower limit is detected, it is possible to accurately detect whether the lamp ambient temperature is low or not, and the period during which the lamp is dimmed is several millimeters. Since it is about 2 seconds, it is not recognized that the lamp is substantially dimmed to the human eye. Therefore, by detecting whether or not the lamp ambient temperature is low in the entire dimming range including the rated output, the dimming curve is corrected as shown in FIGS. 2 and 3 according to the detection result. Thus, it is possible to surely avoid extinction and to perform dimming control without narrowing the operation range of the dimmer.

(Embodiment 5)
A lighting fixture according to Embodiment 5 of the present invention will be described. An example of the external appearance of the lighting fixture of this embodiment is shown in FIG. The illuminating device 30 in this embodiment includes a fluorescent lamp La, a socket 32 that electrically connects and holds the fluorescent lamp to a lighting circuit, and a housing 31 that houses the lighting circuit. As the lighting circuit, the lighting circuit described in the first to fourth embodiments is built in the housing 31 to constitute one lighting fixture. The lighting apparatus is connected to a commercial power supply to be supplied to the lighting circuit, and a dimming signal is given from the outside by means of wired or wireless. By using one or a plurality of such lighting fixtures, it is possible to provide a lighting device that is less likely to disappear than before.

  The fluorescent lamp La is not limited to the illustrated straight tube shape, and may be a ring shape, a double ring shape, a bent shape, or the like.

It is a circuit diagram of Embodiment 1 of the present invention. It is a characteristic view which shows the relationship between the light control signal of Embodiment 1 of this invention, and an inverter operating frequency. It is a characteristic view which shows the relationship between the light control signal of Embodiment 1 of this invention, and lamp | ramp electric power. It is a characteristic view which shows the relationship between the light control signal of Embodiment 1 of this invention, and a lamp voltage detection signal. It is a circuit diagram of Embodiment 2 of the present invention. It is a characteristic view which shows the relationship between the light control signal of Embodiment 2 of this invention, and a lamp DC voltage detection signal. It is a wave form diagram which shows the lamp voltage at the time of the start of Embodiment 3 of this invention. It is a circuit diagram of Embodiment 4 of the present invention. It is a wave form diagram which shows the lamp current of Embodiment 4 of this invention. It is a wave form diagram which shows the lamp voltage of Embodiment 4 of this invention. It is a wave form diagram which shows the lamp DC voltage detection signal at the time of normal temperature of Embodiment 4 of this invention. It is a wave form diagram which shows the lamp DC voltage detection signal at the time of the low temperature of Embodiment 4 of this invention. It is a characteristic view which shows the relationship between the alternating current component of a lamp voltage, and ambient temperature. It is a characteristic view which shows the light control characteristic of a prior art example. It is a perspective view which shows the external appearance of the lighting fixture of Embodiment 5 of this invention.

Explanation of symbols

La lamp 1 control circuit 2 control circuit 3 inverter 4 resonance circuit 5 load circuit 6 microcomputer 7 dimmer 8 lamp voltage detection circuit 9 lamp DC voltage detection circuit 62 dimming curve correction means

Claims (6)

An inverter including at least one switching element connected to an output end of a DC power supply; a load circuit capable of connecting a discharge lamp to the output end of the inverter via a resonance circuit; and a coldest spot of the discharge lamp A detection circuit that detects a characteristic that defines the operation of the discharge lamp that changes due to the influence of temperature and outputs a detection signal, and a dimming control that receives the dimming signal and changes the output of the inverter in accordance with the dimming signal In the discharge lamp lighting device, the dimming control unit, when the detection signal exceeds a predetermined reference value set according to the dimming signal, the discharge lamp power according to the dimming signal A dimming curve correcting means for correcting a dimming curve which is a change, and the dimming curve correcting means has a dimming curve slope when the coldest spot temperature of the discharge lamp is lower than the coldest spot temperature at normal temperature. By reducing The lamp power is corrected in the direction of increasing, and when the coldest spot temperature of the discharge lamp is higher than the coldest spot temperature at normal temperature, the lamp power is corrected by increasing the slope of the dimming curve. A discharge lamp lighting device. The dimming curve correcting means corrects the slope of the dimming curve so that the change width of the dimming signal in which the discharge lamp power changes even after correction is the same as that before the correction. Discharge lamp lighting device. The characteristic that defines the operation of the discharge lamp detected in a dimming state is a DC component of the discharge lamp voltage, and the detection signal detects a value corresponding to the DC component of the discharge lamp voltage. The discharge lamp lighting device according to 1 or 2. The characteristic that regulates the operation of the discharge lamp is the starting voltage at which the discharge lamp is lit. The discharge lamp voltage is gradually increased from the pre-filament preheating to the starting time of the discharge lamp, and a value corresponding to the voltage at which the discharge lamp starts is detected. The discharge lamp lighting device according to any one of claims 1 to 3, wherein: The dimming control unit performs dimming intermittently in a short period of time that cannot be recognized by human eyes from the rated output to the dimming lower limit, and the detection circuit has a characteristic that regulates the operation of the discharge lamp during the period. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device detects and outputs a detection signal. An illumination fixture comprising: the discharge lamp lighting device according to any one of claims 1 to 5; and a discharge lamp whose lighting operation is controlled by the discharge lamp lighting device.

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