JP4590718B2 - High pressure discharge lamp lighting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-pressure discharge lamp lighting device, and more particularly to an electronic lighting device capable of dimming and lighting a high-intensity high-pressure discharge lamp (HID lamp).
[0002]
[Prior art]
A block diagram of a conventional high pressure discharge lamp lighting device is shown in FIG. 4, and a specific circuit diagram is shown in FIG. The rectifier circuit 1 is composed of a diode bridge circuit, and full-wave rectifies the AC voltage of the commercial AC power supply Vs. A power supply circuit 2 having a boosting function and a power factor improvement function is connected to the output of the rectifier circuit 1. The power supply circuit 2 is composed of a boost chopper circuit composed of an inductor L1, a switching element Q1, a diode D1, and a smoothing capacitor C1, and boosts the output voltage of the rectifier circuit 1 to convert it into a predetermined DC voltage V1. The control circuit 3 performs on / off control of the switching element Q1 at a high frequency so that the output voltage V1 of the boost chopper circuit becomes a predetermined voltage. A power conversion circuit 4 having a step-down function is connected to the output of the power supply circuit 2. The power conversion circuit 4 includes a step-down chopper circuit including an inductor L2, a switching element Q2, a diode D2, and an output capacitor C2. The power conversion circuit 4 steps down the output voltage V1 of the power supply circuit 2 and converts it to a predetermined DC voltage V2. The control circuit 5 detects the output voltage V2 of the step-down chopper circuit and performs on / off control of the switching element Q2 at a high frequency so as to supply desired power to the discharge lamp La. A polarity inversion circuit 6 is connected to the output of the power conversion circuit 4. The polarity inversion circuit 6 is composed of a full bridge circuit composed of switching elements Q3 to Q6, and converts the output voltage V2 of the power conversion circuit 4 into a low-frequency rectangular wave voltage and applies it to the high-pressure discharge lamp La. The switching elements Q3 to Q6 of the polarity inverting circuit 6 are driven at a low frequency by the output of the driving circuit 7. The igniter circuit 8 connected in series with the discharge lamp La includes a pulse transformer for generating a high voltage to start the discharge lamp La, and the high voltage output from the secondary winding is discharged via the capacitor C3. It is comprised so that it may apply to the both ends of electric lamp La.
[0003]
Next, the operation of the discharge lamp lighting device configured as described above will be outlined. When the power is turned on, the switching element Q1 of the step-up chopper circuit is turned on / off at a frequency of several tens to several hundreds of kHz by a control signal from the control circuit 3, and a predetermined voltage V1 is obtained from the full-wave rectified voltage of the AC power supply Vs. Is generated. Using the voltage V1 as a power source, the switching element Q2 of the step-down chopper circuit is turned on / off at a frequency of several tens to several hundreds of kHz by a signal from the control circuit 5 to generate a predetermined voltage V2 (0 <V2 <V1). At this time, since the discharge lamp La is in a non-lighting state and substantially in a no-load state, V2 is generally substantially equal to V1. In addition, switching elements Q3, Q6 and Q4, Q5 are paired in response to a drive signal from the drive circuit 7 and are alternately turned on / off at several tens to several hundreds of Hz, and the igniter circuit 8 is operated and released. A rectangular wave voltage on which high voltage pulses are superimposed is applied to both ends of the electric lamp La, and the discharge lamp La is started. When the discharge lamp La is started, the step-down chopper circuit 4 operates so that a predetermined voltage Vla and current Ila are applied to the discharge lamp La. As a result, the discharge lamp La is stably lit with a low-frequency rectangular wave. . FIG. 6 shows the above series of operations.
[0004]
[Problems to be solved by the invention]
By the way, when the discharge lamp La is dimmed, the light is generally dimmed by controlling the value of the current Ila flowing through the lamp and reducing the power Wla applied to the discharge lamp La. Also in the configuration shown in FIG. 5, as shown in FIG. 7, the dimming signal LS is given from the dimmer 9 for setting the target dimming power from the outside, and the output of the control circuit 5 of the step-down chopper circuit 4 is provided. Dimming is possible by controlling the output current by controlling the signal and reducing the output power.
[0005]
However, when the light is adjusted by the control circuit 5 from the stable lighting state and shifts to the dimming lighting, the discharge lamp La does not instantaneously follow the dimming control due to the temperature or pressure inside the arc tube. It will go through a transitional state until it reaches a stable state. In this state, when the polarity inversion circuit 6 is operated by the drive signal from the drive circuit 7 and the polarity of the voltage Vla and the current Ila applied to the discharge lamp La is reversed, the discharge becomes unstable and flickers or disappears. Problems arise.
[0006]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-pressure discharge lamp lighting device capable of stably dimming and lighting a discharge lamp.
[0007]
[Means for Solving the Problems]
According to the present invention, in order to solve the above-described problem, as shown in FIG. 1, a DC power source 2, a power converter 4 that converts the output voltage V <b> 1 of the DC power source 2, and an output of the power converter 4 A polarity inversion unit 6 that converts the voltage V2 into a low-frequency rectangular wave voltage, a high-pressure discharge lamp La that is driven by the output voltage of the polarity inversion unit 6, and a start that applies a high-voltage pulse for starting to the high-pressure discharge lamp La In the high pressure discharge lamp lighting device comprising the device 8 and lighting the high pressure discharge lamp La in a rectangular wave, at least when the power changes from full lighting to dimming lighting, the polarity reversing operation of the polarity reversing unit 6 is stopped, The high-pressure discharge lamp La is lit in a DC lighting state .
[0008]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 shows a circuit diagram of Embodiment 1 of the present invention. Components having the same configuration and operation as those of the conventional example (FIG. 7) are denoted by the same reference numerals. The difference from the prior art is the operation during dimming of the control circuit 5A that controls the step-down chopper circuit 4 that is a power conversion circuit and the drive circuit 7A that controls and drives the polarity inversion circuit 6. The control circuit 5A and the drive circuit 7A are the same in basic operation as the control circuit 5 and the drive circuit 7 shown in the conventional example (FIG. 7). The difference is that when the output signal of the control circuit 5A of the step-down chopper circuit 4 is controlled by the dimming signal LS from the dimmer 9, the dimming signal LS from the dimmer 9 is input, As shown in FIG. 2, switching elements Q3 and Q6 of the polarity inversion circuit 6 during a period until the discharge is stabilized after reaching the predetermined dimming power set by the dimming signal LS after the dimming control is performed. Is turned off, Q4 and Q5 are turned on (or Q3 and Q6 are turned on, Q4 and Q5 are turned off), and a drive circuit control signal DS for stopping the polarity inversion operation is supplied to the drive circuit 7A. It is a point to give. In response to this drive circuit control signal DS, the drive circuit 7A stops the polarity reversal operation of the polarity reversal circuit 6, turns on the discharge lamp La in the DC lighting state, and then operates the polarity reversal circuit 6 again to generate a rectangular wave. It controls to perform lighting. The above operation is conceptually shown in FIG.
[0009]
In this way, by controlling so that the operation of the polarity reversal circuit 6 is stopped when the power changes from full lighting to dimming lighting, it is possible to prevent discharge instability in the transient state of the lamp during dimming. The discharge lamp La can be dimmed stably.
[0010]
Note that the present invention is not limited to the configuration shown in the above embodiment, and is effective for all the high-pressure discharge lamp lighting devices that perform rectangular wave lighting of the discharge lamp La and that realize dimming lighting.
[0011]
【The invention's effect】
As described above, according to the present invention, in the high pressure discharge lamp lighting device for lighting the high pressure discharge lamp in the rectangular wave, at least when the lamp power changes from full lighting to dimming lighting, the polarity reversing operation of the polarity reversing unit is performed. Since the high-pressure discharge lamp is turned on in the DC lighting state after being stopped , the high-pressure discharge lamp can be stably dimmed and problems such as flickering and extinction can be solved.
[Brief description of the drawings]
FIG. 1 is a specific circuit diagram of a high pressure discharge lamp lighting device according to a first embodiment of the present invention.
FIG. 2 is a waveform diagram for explaining the operation of the high pressure discharge lamp lighting device according to the first embodiment of the present invention.
FIG. 3 is an explanatory view conceptually showing the operation of the high pressure discharge lamp lighting device of the present invention.
FIG. 4 is a schematic configuration diagram of a conventional high pressure discharge lamp lighting device.
FIG. 5 is a specific circuit diagram of a conventional high pressure discharge lamp lighting device.
FIG. 6 is a waveform diagram for explaining the operation of a conventional high pressure discharge lamp lighting device.
FIG. 7 is a specific circuit diagram of a conventional high pressure discharge lamp lighting device having a dimming function.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rectification circuit 2 Power supply circuit 3 Control circuit 4 Power conversion circuit 5A Control circuit 6 Polarity inversion circuit 7A Drive circuit 8 Igniter circuit 9 Dimmer

Claims (1)

DC power source, power conversion unit for converting the output voltage of the DC power source, polarity inversion unit for converting the output voltage of the power conversion unit to a low-frequency rectangular wave voltage, and a high voltage driven by the output voltage of the polarity inversion unit In a high-pressure discharge lamp lighting device that includes a discharge lamp and a high-voltage discharge lamp that applies a high voltage pulse for starting to the high-pressure discharge lamp, the high-voltage discharge lamp is operated in a rectangular wave. A high pressure discharge lamp lighting device characterized by stopping a polarity reversing operation of a polarity reversing section and lighting a high pressure discharge lamp in a DC lighting state at the time of change.

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