JP4196059B2 - Discharge lamp lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp lighting device, and more particularly to a control power supply circuit of a discharge lamp lighting device that lights a HID lamp.
[0002]
[Prior art]
As a circuit for lighting a fluorescent lamp, an HID lamp, etc., there are a circuit using a so-called copper iron ballast and a circuit using a discharge lamp lighting device called an electronic ballast. FIG. 12 is a diagram showing a discharge lamp lighting circuit using a copper iron ballast. In this circuit, a copper iron ballast 103 is connected in series between a commercial AC power supply 101 and a lamp 104. The capacitor 102 is for noise prevention.
[0003]
FIG. 13 is a block diagram showing a schematic configuration of the electronic ballast. A DC power supply circuit 2 including a rectifier circuit is connected to a commercial AC power supply 1, and an inverter circuit 3 is connected to the output side of the DC power supply circuit 2. The lamp 4 is connected to the output side of the inverter circuit 3, and the power supplied to the lamp 4 is adjusted and controlled. In recent years, electronic ballast has become the mainstream in place of copper-iron ballasts for the purpose of reducing the weight, size and functionality of ballasts.
[0004]
FIG. 14 shows a specific circuit example of a conventional electronic ballast. The DC power supply circuit 2 includes a rectifier circuit 5, a switching element 6, a diode 7, an inductance 8, a capacitor 9, and a control circuit 10. The step-up chopper circuit is constituted by the switching element 6, the diode 7 and the inductance 8, and this step-up chopper circuit has a function of rectifying and smoothing the AC voltage from the AC power source 1 into a DC voltage.
[0005]
The inverter circuit 3 includes a switching element 11, a diode 12, an inductance 13, a capacitor 14, and a control circuit 15, and the switching element 11, the diode 12 and the inductance 13 constitute a step-down chopper circuit. The control circuit 15 detects the lamp voltage Vla (which may be current or power) supplied to the lamp 4 and performs on / off control of the switching element 11 in accordance with the lamp voltage Vla, thereby supplying the power supplied to the lamp 4. It is adjusted. The frequency of power supplied to the lamp 4 is determined by the polarity inversion circuit 4a, and is usually set to several tens to several hundreds Hz. The transformer 20 supplies the voltage generated by the igniter control circuit 21 to the lamp 4 and starts lighting the lamp.
[0006]
A control power supply circuit 17 including a capacitor 16 is provided as a power supply circuit for the control circuits 10 and 15. The capacitor 16 is charged from the voltage generated in the secondary winding of the inductance 8 through the diode 18 and the resistor 19 and supplies power to the control circuits 10 and 15. A three-terminal regulator may be added to the output side of the capacitor 16 of the control power supply circuit 17. Thus, in order to supply power from the secondary winding of the inductance 8, it is necessary that the DC power supply circuit 2 operates and a predetermined current flows through the inductance 8.
[0007]
In general, a high-pressure discharge lamp tends to increase the lamp voltage as time elapses from the start of lighting. In the case of a lighting circuit using a copper iron ballast, if the lamp voltage increases, the re-ignition voltage of the lamp increases, so that it becomes difficult to maintain the lighting, and so-called extinction may occur. FIG. 15 shows a lamp voltage waveform and a lighting sustain voltage waveform in the copper iron ballast. When the lamp voltage waveform overlaps the sustaining voltage waveform, the lamp goes out.
[0008]
On the other hand, in the electronic ballast, since the re-ignition voltage does not rise compared with the copper iron ballast even at the end of the life, the extinction hardly occurs. Therefore, the life of the lamp is longer in the lighting circuit using the electronic ballast than in the copper-iron ballast. However, in the case of an electronic ballast that does not easily turn off, the load applied to the lamp is greater than that of a copper-iron ballast, and the lamp may be damaged. Therefore, there is also an electronic ballast that executes control for automatically stopping power to the lamp in order to prevent the lamp from being damaged.
[0009]
However, in a room or the like where only one lighting fixture is installed, it is inconvenient to stop the power to the lamp and turn off the lighting fixture. Therefore, there is a lighting device configured to control the power supplied to the lamp when the lamp voltage becomes higher than a predetermined voltage. For example, when the lamp voltage becomes higher than a predetermined voltage, the lamp needs to be replaced while ensuring a certain level of brightness rather than turning off the lamp completely by halving the power supplied to the lamp. The user can be notified of this.
[0010]
[Problems to be solved by the invention]
In the lighting device as described above, even when the lamp reaches the end of its life and the power supplied to the lamp is reduced to ½, it may go out. In other words, since the lamp itself is at the end of its life, the discharge becomes unstable due to electrode wear and the like, and when the power supplied to the lamp is suddenly reduced, the lamp voltage rises momentarily. As a result, the re-ignition voltage or the like may exceed the lighting maintenance voltage and cause the light to disappear.
[0011]
The present invention solves the above-described conventional problems, includes a DC power supply circuit unit and an inverter circuit unit, and notifies that the lamp is at the end of its life by reducing the power supply to the lamp. It is an object of the present invention to provide a discharge lamp lighting device that does not easily disappear.
[0012]
[Means for Solving the Problems]
A discharge lamp lighting device according to claim 1 of the present invention includes a DC power supply circuit including a rectifier circuit, a lighting circuit having at least one switching element connected to the output side of the DC power supply circuit and lighting a high-pressure discharge lamp. Detecting means for detecting a lamp voltage of the high-pressure discharge lamp; life determining means for determining that the high-pressure discharge lamp has a lifetime based on an output signal of the detection means; and determining that the high-pressure discharge lamp has a lifetime And a control means for reducing power supplied to the high-pressure discharge lamp when the control means determines that the high-pressure discharge lamp is at the end of its life. by increasing the output voltage of the DC power supply circuit, the lamp voltage than reignition voltage reduces the supply power of the high pressure discharge lamp after increasing, then after the lamp of the high pressure discharge lamp is lighted stable Characterized in that to lower the output voltage of the serial DC power supply circuit.
[0015]
In the discharge lamp lighting device according to claim 2 of the present invention, when it is determined that the high-pressure discharge lamp has a life and the output voltage of the DC power supply circuit is increased, the power supplied to the lamp of the high-pressure discharge lamp is Is controlled so as not to exceed a predetermined power.
[0016]
In a discharge lamp lighting device according to a third aspect of the present invention, the lighting circuit includes a switching element and an inductor, the switching element is turned on / off at high frequency, and the switching frequency or duty ratio is controlled to control the high pressure discharge. Equipped with a control circuit that controls the power supplied to the lamp of the lamp, and has a detecting means for detecting the current flowing through the inductor, and the switching means is controlled by the detecting means to set the maximum ON width of the switching element. When the life determining means determines that the lamp is at the end of its life, the control means increases the maximum ON width of the switching element, and then reduces the power supplied to the lamp. And
[0017]
In the discharge lamp lighting device according to claim 4 of the present invention, when the life determining means determines that the lamp of the high-pressure discharge lamp has a life, the control means increases the maximum ON width of the switching element. The power supplied to the lamp is reduced, and the maximum ON width of the switching element is reduced after the lamp is in a stable lighting state.
[0019]
In the discharge lamp lighting device according to claim 5 of the present invention, the control means controls the power supplied to the high pressure discharge lamp so that the voltage of the high pressure discharge lamp does not exceed a predetermined value. The output is gradually decreased with a predetermined time constant.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0021]
(First embodiment)
FIG. 1 is a circuit diagram of an electronic ballast that is a discharge lamp lighting device according to a first embodiment of the present invention. Constituent elements having the same functions as those in the circuit diagram shown in FIG. This electronic ballast includes a step-up chopper circuit 2 connected to an AC power source 1, a step-down chopper circuit 3 connected to the output side thereof, an igniter circuit composed of a transformer 20 and an igniter control circuit 21, a lamp 4, The control circuits 10 and 15 and the control power supply circuit 17 of the step-up chopper circuit 2 and the step-down chopper circuit 3 and the lamp voltage determination circuit 28 are provided.
[0022]
Description of configurations and functions of the step-up chopper circuit 2, the step-down chopper circuit 3, the transformer 20, the igniter control circuit 21, the control circuits 10 and 15, etc. having the same functions as those in the circuit diagram shown in FIG. Will be described. The lamp voltage determination circuit 28 outputs an H signal when the lamp 4 is above a predetermined value, that is, when the lamp is at the end of its life.
[0023]
In FIG. 1, it is assumed that the output voltage Vdc of the step-up chopper circuit 2 and the output voltage Vla of the step-down chopper circuit 3 are substantially equal when the lamp 4 is not lit or connected, that is, in a so-called no-load state. . At this time, the lamp sustaining voltage is Vdc.
[0024]
Next, the case where the lamp 4 has reached the end of its life and the lamp voltage has increased will be described with reference to FIG. FIG. 2 is a time chart showing changes in each voltage signal as the lamp voltage increases in the first embodiment of the present invention. In FIG. 2, when the lamp voltage rises, the output signal of the comparator 26 constituting the lamp voltage determination circuit 28 changes from L level to H level. In response to this output signal, the control circuit 10 changes the output voltage of the step-up chopper circuit 2 from V0 to V1. Here, V0 <V1. Since the output voltage Vla of the step-down chopper circuit 3 is substantially equal to Vdc in the lamp no-load state, the lighting maintenance voltage of the lamp 4 becomes V1. At this time, the control circuit 15 operates so that the lamp power does not increase even if Vdc increases. After the step-up chopper circuit 2 performs the above operation, the control circuit 15 decreases the power supplied to the lamp 4.
[0025]
FIG. 10 is a diagram illustrating a lighting sustain voltage waveform and a lamp voltage waveform. A solid line shows a lighting sustain voltage and a lamp voltage waveform during normal lighting, and a broken line shows a lighting maintenance voltage and a lamp voltage waveform in the present embodiment. By increasing the sustaining voltage waveform as indicated by the broken line, the waveforms do not overlap even if the re-ignition voltage of the lamp voltage waveform increases as indicated by the broken line. Therefore, once the lighting maintenance voltage is increased, the power can be reduced without causing the lamp 4 in the end of life state to go out.
[0026]
(Second Embodiment)
FIG. 3 is a time chart showing changes in each voltage signal as the lamp voltage increases in the second embodiment of the present invention. In this embodiment, the operation of the boost chopper circuit 2 is controlled as shown in FIG. 3 in the circuit diagram of FIG. In the high-pressure discharge lamp, when the supply power is suddenly reduced as described above, the re-ignition voltage and the lamp voltage are remarkably increased, and the lamp voltage becomes constant when the lamp power is stabilized.
[0027]
In the first embodiment, after the lamp life determination circuit 28 outputs the H signal, the output voltage Vdc of the step-up chopper circuit 2 maintains V1 after the lamp power is reduced. In the process of reducing the power, the output voltage Vdc is set to V1, and after stabilization, returned to V0.
[0028]
In this manner, during the period when the lamp power suddenly changes, the lighting sustaining voltage is raised to prevent the lamp 4 from turning off, and when the lamp power becomes stable thereafter, the output voltage Vdc of the boost chopper circuit 2 is returned to V0 again. By doing so, the power loss of the step-up chopper circuit 2 and the step-down chopper circuit 3 can be reduced.
[0029]
(Third embodiment)
FIG. 4 is a circuit diagram of an electronic ballast that is a discharge lamp lighting device according to a third embodiment of the present invention. In FIG. 4, the relationship between the output voltage Vdc of the step-up chopper circuit 2 and the output voltage Vla of the step-down chopper circuit 3 in the lamp no-load state is Vdc> Vla. For example, when Vdc = 400V, the output voltage is lowered such that Vla = 280V from the viewpoint of safety.
[0030]
As shown in FIG. 5, a detected value (for example, a lamp voltage) of a certain lamp is set as a reference value A, and an instantaneous value X when a current flowing through the step-down chopper circuit 3 is detected as a voltage across the resistor 33 is a reference value. When A, the OFF signal is sent to Q3, and when the current instantaneous value X becomes the reference value B or less, the ON signal is sent again to Q3 to control the power supplied to the lamp. In this case, as shown in the time chart of FIG. 6, the maximum value C of the ON width of Q3 when the lamp is lit and when the lamp is not loaded is set so as not to exceed this maximum value in any case. .
[0031]
When the lamp is going to go out, the re-ignition voltage rises as shown in FIG. 11, and the waveform of the lamp current also changes and the overshoot current increases. If the lighting maintenance voltage of the lighting device is equal to or lower than the re-ignition voltage of the lamp, the lamp goes out. The same applies to the lamp current. If the supply from the lighting device is smaller than the overshoot current, the lamp will go out. Therefore, when the extinction is likely to occur, the extinction can be prevented by setting the ON width to be larger than the maximum value normally set for supplying energy to the lamp.
[0032]
The circuit operation of this embodiment will be described. When the lamp life determination circuit 28 determines that the lamp 4 has reached the end of its life, the comparator 26 outputs an H signal. In response to this signal, the value for setting the maximum ON width of the control circuit 15 is changed.
[0033]
For example, as shown in FIG. 6, the maximum value C is set in the normal state, and the set value D is set when the lamp life determination circuit 28 is operated. According to this, the supply capability to the lamp is increased, and it is possible to supply a current even at an instantaneous overshoot current even if the lamp goes out. Thereafter, the control circuit 15 lowers the power supplied to the lamp 4. Thus, the disappearance can be prevented also in this embodiment.
[0034]
(Fourth embodiment)
This embodiment will also be described using the circuit of the third embodiment shown in FIG. Only the parts different from the third embodiment will be described. In the third embodiment, the setting value D is used to change the maximum ON width after the lamp life determination circuit 28 determines that the lamp 4 has reached the end of its life. However, in this embodiment, the power supplied to the lamp is reduced. After the lamp 4 is steadily lit, the maximum ON width setting is returned to the maximum value C again.
[0035]
As a result, the maximum ON width changes only when the power supplied to the lamp 4 is to be reduced. Also in the present embodiment, the lamp power can be reduced without the occurrence of extinction even in the end-of-life state of the lamp 4.
[0036]
(Fifth embodiment)
FIG. 7 is a time chart showing the change of each voltage signal as the lamp voltage increases in the fifth embodiment of the present invention. The circuit configuration of the electronic ballast is the same as that shown in FIG.
[0037]
When the lamp life determination circuit 28 determines that the lamp 4 has reached the end of its life, the comparator 26 outputs an H signal. In response to this, the control circuit 15 decreases the power supplied to the lamp 4, but does not decrease the power supplied suddenly, but instead reduces the lamp power at a predetermined time constant so that the increase in the lamp voltage of the lamp 4 is reduced. Decrease. Also in this embodiment, when the power is reduced at the end of the lamp life, it is possible to prevent the lamp from turning off.
[0038]
In the present embodiment, any one or a plurality of the first to fourth embodiments may be combined.
[0039]
(Sixth embodiment)
FIG. 8 is a circuit diagram of an electronic ballast that is a discharge lamp lighting device according to a sixth embodiment of the present invention. Constituent elements having the same functions as those of the circuit diagram shown in FIG. In the circuit configuration of this embodiment, resistors 29 and 30 are connected in series to the output side of the step-down chopper circuit 3 as a lamp voltage detection circuit, and the voltage at the connection point of both resistors 29 and 30 is input to the control circuit 15.
[0040]
When the lamp life determination circuit 28 determines that the lamp 4 has reached the end of its life, the comparator 26 outputs an H signal. Upon receiving this signal, the control circuit 15 reduces the power supplied to the lamp 4. When the lamp power changes, the voltage of the lamp 4 and the re-ignition voltage increase. When the voltage obtained by dividing this voltage by the resistors 29 and 30 becomes a predetermined value or more, the control circuit 15 reduces the degree of decrease in the lamp power. FIG. 9 is a time chart after the comparator 26 of the lamp life determination circuit 28 outputs the H signal. A portion A in which the lamp voltage is increasing indicates a process in which the supplied voltage is decreased and the lamp voltage is increased. B is a portion that suppresses a decrease in the supplied power because the lamp voltage has reached a predetermined level, and indicates that the lamp voltage has not increased by a predetermined value or more. The portion C indicates that the lamp voltage has become equal to or lower than a predetermined value, so that the supply power is lowered again to shift to stable lighting.
[0041]
That is, when the lamp power is reduced, the lamp voltage or the re-ignition voltage can be set to a voltage higher than a predetermined value as the lighting sustaining voltage in order to reduce the supply power while monitoring the change in the lamp voltage. Can be prevented from disappearing.
[0042]
As described above, in the first to sixth embodiments, the case where the step-up chopper circuit is used as the DC power supply circuit has been described. However, a step-down chopper circuit or a step-up / step-down chopper circuit may be used. In addition, although a circuit in which a step-down chopper circuit and a polarity inversion circuit are connected is used as the lighting circuit, the same effect can be obtained in a lighting device configured with a half-bridge circuit and a full-bridge circuit.
[0043]
Further, in each of the above embodiments, it is determined that the end of life state is reached when the lamp voltage becomes equal to or higher than the predetermined voltage. However, the initial lamp voltage is stored, and the increase amount of the lamp voltage is set to the predetermined value. If it reaches, it may be determined that the end of life is reached. By so doing, it is possible to absorb the variation in the lamp voltage in the initial stage and to make an accurate determination.
[0044]
The present invention is not limited to the specific circuit examples shown in the above embodiments and the drawings, and can be implemented in various forms and circuit configurations.
[0045]
【The invention's effect】
As described above, according to the discharge lamp lighting device of the present invention, in the discharge lamp lighting device including the DC power supply circuit unit, the inverter circuit unit, and the lamp life determination circuit, the output is performed in the end of life state where the lamp voltage increases. Therefore, the power supplied to the lamp can be reduced without causing the lamp to turn off.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an electronic ballast that is a discharge lamp lighting device according to a first embodiment of the present invention.
FIG. 2 is a time chart showing changes in each voltage signal as the lamp voltage increases in the first embodiment of the present invention.
FIG. 3 is a time chart showing changes in each voltage signal accompanying an increase in lamp voltage in the second embodiment of the present invention.
FIG. 4 is a circuit diagram of an electronic ballast that is a discharge lamp lighting device according to a third embodiment of the present invention.
FIG. 5 is a time chart showing the relationship between a current detection value and a control signal in the third embodiment.
FIG. 6 is a time chart showing a relationship between a current detection value and a control signal in the third embodiment.
FIG. 7 is a time chart showing changes in each voltage signal accompanying an increase in lamp voltage in the fifth embodiment of the present invention.
FIG. 8 is a circuit diagram of an electronic ballast that is a discharge lamp lighting device according to a sixth embodiment of the present invention.
FIG. 9 is a time chart after the comparator of the lamp life determination circuit according to the sixth embodiment of the present invention outputs an H signal.
FIG. 10 is a diagram showing a lighting sustain voltage waveform and a lamp voltage waveform according to the first embodiment of the present invention.
FIG. 11 is a time chart showing the relationship between a current detection value and a control signal in the third embodiment.
FIG. 12 is a diagram showing a discharge lamp lighting circuit using a copper-iron ballast.
FIG. 13 is a block diagram showing a schematic configuration of an electronic ballast.
FIG. 14 is a diagram illustrating a specific circuit example of a conventional electronic ballast.
FIG. 15 is a diagram showing a lamp voltage waveform and a lighting sustain voltage waveform in a copper-iron ballast.
[Explanation of symbols]
5 rectifier circuit 2 DC power supply circuit 4 high-pressure discharge lamp 3 lighting circuits 24 and 25 detection means 28 life determination means 10 and 15 control means

Claims (5)

A direct current power supply circuit including a rectifier circuit; a lighting circuit connected to an output side of the direct current power supply circuit and having at least one switching element for lighting the high pressure discharge lamp; and a detecting means for detecting a lamp voltage of the high pressure discharge lamp; A life discriminating means for discriminating that the high pressure discharge lamp is at the end of its life based on an output signal of the detecting means; and a reduction in power supplied to the high pressure discharge lamp when it is determined that the high pressure discharge lamp is at the end of its life A discharge lamp lighting device comprising: a control means for causing a lamp voltage to increase by increasing an output voltage of the DC power supply circuit when it is determined that the high-pressure discharge lamp has a lifetime. the than reignition voltage reduces the supply power of the high pressure discharge lamp after increasing, then the after the lamp of the high pressure discharge lamp is lit stably lowering the output voltage of the DC power supply circuit The discharge lamp lighting device according to symptoms. The control means determines that the power supplied to the lamp of the high pressure discharge lamp does not exceed a predetermined power when it is determined that the high pressure discharge lamp has a life and the output voltage of the DC power supply circuit is increased. The discharge lamp lighting device according to claim 1 , wherein the discharge lamp lighting device is controlled. The lighting circuit includes a switching element and an inductor, and the switching element is turned on / off at a high frequency, and includes a control circuit that controls power supplied to the lamp of the high-pressure discharge lamp by controlling a switching frequency or a duty ratio. , Having a detecting means for detecting the current flowing through the inductor, controlling the on / off of the switching element by the detecting means, having a set value for setting the maximum on-width of the switching element, and that the lamp has a lifetime 3. The discharge lamp lighting device according to claim 1, wherein when the life determination unit determines, the control unit increases the maximum ON width of the switching element, and then decreases the power supplied to the lamp . When the life discriminating means discriminates that the lamp of the high-pressure discharge lamp is at the end of its life, the control means reduces the power supplied to the lamp after widening the maximum ON width of the switching element, so that the lamp is stable. 4. The discharge lamp lighting device according to claim 3, wherein the maximum ON width of the switching element is reduced after being turned on . The control means gradually decreases the output of the high pressure discharge lamp with a predetermined time constant while controlling the power supplied to the high pressure discharge lamp so that the voltage of the high pressure discharge lamp does not exceed a predetermined value. The discharge lamp lighting device according to claim 3 .

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