JP2009224080A - Discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable transition to low brightness having a low resonance output voltage without causing lighting failure, and to enable recognition of the brightness level currently used and a brightness level after changing it, when light is controlled. <P>SOLUTION: When changing and controlling the brightness of a discharge lamp from first brightness to second brightness, after making a drive circuit once control the frequency of a high-frequency current so that the output current of a resonance circuit changes into a current higher than a target current by which the second brightness can be obtained, the drive circuit is made to control the frequency of the high-frequency circuit so that the output current changes into a target current. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device capable of switching the output of a discharge lamp, for example.

  A discharge lamp lighting device that performs high-frequency lighting generally uses a high-voltage integrated circuit. The high-voltage integrated circuit is a driver for driving a power switching element that performs high-frequency switching, and can simplify the circuit and save space. The operating frequency of high-frequency switching of the high-voltage integrated circuit is determined in proportion to a time constant determined by the resistance value of the resistor connected to the high-voltage integrated circuit and the capacitance of the capacitor. Therefore, in a discharge lamp lighting device using a high voltage integrated circuit, the operating frequency of the high voltage integrated circuit can be changed by switching a resistor or a capacitor connected to the high voltage integrated circuit. By changing the operating frequency of the high voltage integrated circuit, it is possible to perform a preheating operation, a lamp starting operation, and a lighting operation necessary for controlling the lighting of the discharge lamp.

  Similarly, in a discharge lamp lighting device using a high voltage integrated circuit, the operating frequency of the high voltage integrated circuit is changed by switching a resistor or a capacitor connected to the high voltage integrated circuit, thereby dimming the discharge lamp. It is also possible to control (switching of output).

In addition, there is a discharge lamp lighting device that performs dimming control of the discharge lamp, and performs dimming by turning off / on the power supply.
JP-A-3-269996 JP-A-10-149889

High frequency lighting of a discharge lamp is generally performed by a resonance circuit. The dimming control uses a region where the resonant output voltage is low. For this reason, when the discharge lamp is lit under unstable conditions such as in a low temperature atmosphere, or when the discharge is not stable immediately after lighting, that is, immediately after the breakdown of the discharge, the dimming level (brightness) There is a risk of disappearing when transitioning to S).
In addition, when there are several levels of dimming levels that can be switched, when dimming control is performed by turning the power OFF / ON, what level is the currently used dimming level and the dimming level after dimming control? I don't know.

An object of the present invention is, for example, to enable dimming control to a dimming level with a low resonant output voltage without causing extinction.
It is another object of the present invention to make it possible to recognize the brightness level currently used and the brightness level after the change when the dimming control is performed.

  The discharge lamp lighting device according to the present invention converts, for example, a DC voltage obtained from a commercial power source into a high-frequency current, operates a resonance circuit having a predetermined characteristic by the converted high-frequency current, and outputs an output current of the resonance circuit. Is applied to the discharge lamp, the drive circuit section is configured to control the frequency of the high-frequency current converted by the inverter circuit, and the brightness of the discharge lamp is changed from the first brightness to the second brightness. In this case, after the drive circuit is once controlled to control the frequency of the high-frequency current so that the output current of the resonance circuit is higher than the target current for obtaining the second brightness, the output of the resonance circuit A dimming transition control circuit unit that controls the drive circuit to control the frequency of the high-frequency current so that the current becomes the target current;

  In the discharge lamp lighting device according to the present invention, when the brightness of the discharge lamp is controlled to be changed from the first brightness to the second brightness, the output current of the resonance circuit can obtain the second brightness. It controls once so that it may become a current higher than an electric current. Therefore, according to the discharge lamp lighting device according to the present invention, the resonance output current can transition to a low dimming level without causing extinction.

Embodiment 1 FIG.
A discharge lamp lighting device according to this embodiment will be described with reference to the drawings.
FIG. 1 is a circuit diagram of a discharge lamp lighting device. The discharge lamp lighting device shown in FIG. 1 includes a power rectifier circuit unit 1, a DC power circuit unit 2 (active filter circuit unit), an inverter circuit unit 3, a load circuit unit 4 (resonance circuit unit), and a drive circuit unit 5.
The power supply rectifier circuit unit 1 is a circuit that rectifies a power supply voltage and removes noise.
The DC power supply circuit unit 2 is a circuit that boosts the power supply voltage to a predetermined DC voltage and shapes the input current waveform to improve the power factor by switching along the power supply voltage waveform.
The inverter circuit 3 alternately switches FETs (Field Effect Transistors) Q1 and Q2 with the reverse polarity voltage output from the drive circuit 5 from the DC voltage boosted by the DC power supply circuit unit 2 to thereby generate a high-frequency current ( This is a circuit that generates a high-frequency voltage and operates the load circuit unit 4.
The load circuit unit 4 is a circuit that applies an output current to the discharge lamp to make it light using the resonance of the inductor L1 and the capacitor C2.
The drive circuit 5 is a circuit that drives the inverter circuit 3, and is a circuit that controls switching of the FETs Q1 and Q2 by the inverter circuit unit 3.

The drive circuit unit 5 will be described in detail. The drive circuit unit 5 includes a high voltage integrated circuit 6, an all-light command unit 7, a dimming command unit 8, and a resistor R1.
The high voltage integrated circuit 6 is a driver for driving a power switching element that performs high frequency switching. The switching of the FETs Q1 and Q2 by the inverter circuit unit 3 is controlled by the operating frequency of the high frequency switching of the high voltage integrated circuit 6. The operating frequency of high frequency switching of the high voltage integrated circuit 6 is determined in proportion to a time constant determined from the resistance value of the resistor connected to the high voltage integrated circuit and the capacitance of the capacitor. The higher the time constant, the lower the operating frequency of high frequency switching of the high voltage integrated circuit 6.
The all-light command unit 7 is a circuit unit that is energized when the discharge lamp is all-lighted. The all-light command unit 7 includes a capacitor C3 and a switch S1.
The dimming command unit 8 is a circuit unit that is energized when the discharge lamp is dimmed and lit (lighter than the all-light). The dimming command unit 8 includes a capacitor C4 and a switch S2.
That is, when the discharge lamp is turned on all the light, the switch 1 is turned on and the switch 2 is turned off, and the operating frequency of the high voltage integrated circuit 6 is determined by a time constant determined by the capacitance of the capacitor C3 and the resistance value of the resistor R1. Is done. When the discharge lamp is dimmed, the switch 2 is turned on, the switch 1 is turned off, and the operating frequency of the high voltage integrated circuit 6 is determined by a time constant determined from the capacitance of the capacitor C4 and the resistance value of the resistor R1. .

FIG. 2 is a frequency / output characteristic graph of the load circuit unit 4.
The case where the discharge lamp lighting device shown in FIG. 1 operates in a region (voltage delay phase region) delayed with respect to the resonance frequency will be described. Therefore, in FIG. 2, when the points A and B are used as the operating frequencies, the point A is the frequency when all the lights are turned on, and the point B higher than the point A is the frequency when the dimming lights are turned on. .
Therefore, the time constant between the capacitor C3 and the resistor R1 of the all-light command unit 7 is larger than the time constant between the capacitor C4 and the resistor R1 of the dimming command unit 8 (time constant of the all-light command unit 7> dimming). Command unit 8 time constant).

Next, switching of the switch when performing dimming control will be described. Here, the case of switching from all-light lighting to dimming lighting will be described as an example. FIG. 3 is a time chart for switching from all-light lighting to dimming lighting.
As shown in FIG. 3, when all the lights are on, the switch 1 is ON and the switch 2 is OFF.
When switching from all-light lighting to dimming lighting (at the time of dimming transition), both the switch 1 and the switch 2 are once turned ON. Since both the switch 1 and the switch 2 are turned on, the time constant of the high voltage integrated circuit 6 is determined by the time constant determined by the combined capacity of the capacity of the capacitor C3 and the capacity of the capacitor C4 and the resistance value of the resistor R1. The operating frequency is determined. That is, the time constant at the time of dimming transition is higher than the time constant at the time of dimming lighting than the time constant at the time of all light lighting. That is, the current applied to the discharge lamp at the time of dimming transition is higher (larger) than at the time of dimming lighting than at the time of all light lighting. In the frequency / output characteristic graph of the load circuit unit 4 shown in FIG. 2, at the time of dimming transition, the load circuit unit 4 operates at a point C that operates at a frequency lower than the all-light command value, for example. The time for which both the switch 1 and the switch 2 are turned on is, for example, about 50 ms (milliseconds).
Then, after both the switch 1 and the switch 2 are once turned on, the switch 1 is turned off. That is, the switch 2 is turned on, the switch 1 is turned off, and the discharge lamp is dimmed.

Here, when there is no high output period of about 50 ms shown in the time chart of FIG. 3, the switch elements 1 and 2 are switched simultaneously when dimming control is performed. As a result, the operating frequency of the high voltage integrated circuit 6 becomes unstable, and the discharge lamp may be extinguished.
On the other hand, as shown in FIG. 3, if the switch 1 is turned off after a high output period of about 50 ms, the operating frequency does not become unstable and the disappearance does not occur.

In the above description, the process of switching from all-light lighting to dimming lighting has been described. However, the process of switching from dimming lighting to all-light lighting is also prevented from disappearing by switching over the high output period. can do.
In addition, in the case of a discharge lamp lighting device that can be switched to a plurality of brightness levels, when switching to each brightness level, it is possible to prevent the lights from disappearing by switching similarly through a high output period.

  In the above description, since the purpose is to prevent the discharge lamp from extinguishing, the high output period is set to about 50 ms, for example. However, in a discharge lamp lighting device that can be switched to a plurality of brightness levels, if it is possible to recognize the brightness level of the current discharge lamp (or after switching), for example, high output The period may be as long as about 500 ms. That is, at the time of dimming control, the current (or after switching) discharge lamp is switched by temporarily switching to a level brighter than the total light output (for example, the highest output) and visually observing the brightness at a level brighter than the total light output. It is possible to recognize how much brightness is.

FIG. 4 is a circuit diagram of a discharge lamp lighting device that detects a predetermined commercial power OFF / ON operation and performs dimming control. The discharge lamp lighting device shown in FIG. 4 includes a dimming transition control circuit unit 9 in addition to the discharge lamp lighting device shown in FIG.
The dimming transition control circuit unit 9 detects a predetermined OFF / ON operation of the commercial power supply and outputs a dimming command to the drive circuit unit 5. The dimming command is a command that prompts dimming control.
When the drive circuit unit 5 receives the dimming command from the dimming transition control circuit unit 9, the drive circuit unit 5 performs dimming control as described above in accordance with the dimming command. That is, in the above description, the drive circuit unit 5 switches from all-light lighting to dimming lighting through a high output period.
The drive circuit unit 5 may be an IC circuit.

  FIG. 5 is a circuit diagram of the discharge lamp lighting device that outputs the dimming command of the dimming transition control circuit unit 9 of the discharge lamp lighting device shown in FIG. 4 to the drive circuit unit 5 by the microcomputer 10. In the discharge lamp lighting device shown in FIG. 6, the above functions can be realized easily and with a small number of components by performing the dimming control by the microcomputer 10.

FIG. 6 is a time chart when detecting a predetermined commercial power OFF / ON operation and switching from all-light lighting to dimming lighting.
In FIG. 6, the dimming transition control circuit unit 9 detects two consecutive OFF / ON operations of the commercial power supply, outputs a dimming command, and performs dimming control. The two continuous OFF / ON operations are operations that are turned on within a predetermined time after the commercial power supply is turned off, further turned off within a predetermined time, and further turned on within a predetermined time. That is, when the dimming transition control circuit unit 9 detects two consecutive OFF / ON operations of the commercial power supply in a state where all the lights are lit, a dimming command is output to the drive circuit unit 5. The drive circuit unit 5 that has received the dimming command switches to dimming lighting after a high output period. In FIG. 6, the high output period is set to 50 ms, but as described above, in the discharge lamp lighting device that can be switched to a plurality of brightness levels, what is the brightness of the current discharge lamp (or after switching)? In the case where it is possible to recognize whether it is brightness, a visible period (for example, about 500 ms) may be used.

  As described above, according to the discharge lamp lighting device according to this embodiment, it is possible to prevent the light from turning off when the light control is performed. Further, when the dimming transition is performed, it is possible to recognize how bright the current (or after switching) discharge lamp is.

The circuit diagram of a discharge lamp lighting device. A frequency / output characteristic graph of the load circuit section 4. The time chart figure in the case of switching from all-light lighting to dimming lighting. The circuit diagram of the discharge lamp lighting device which detects predetermined commercial power supply OFF / ON operation, and performs light control. The circuit diagram of the discharge lamp lighting device which outputs the dimming instruction | command of the dimming transition control circuit part 9 to the drive circuit part 5 by the microcomputer 10. FIG. The time chart figure in the case of detecting predetermined commercial power supply OFF / ON operation and switching from all-light lighting to dimming lighting.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Power supply rectifier circuit part, 2 DC power supply circuit part, 3 Inverter circuit part, 4 Load circuit part, 5 Drive circuit part, 6 High voltage integrated circuit, 7 All light command part, 8 Dimming command part, 9 Dimming transition control Circuit part, 10 microcomputer.

Claims (5)

An inverter circuit unit that converts a DC voltage obtained from a commercial power source into a high-frequency current, operates a resonance circuit having a predetermined characteristic by the converted high-frequency current, and applies an output current of the resonance circuit to a discharge lamp;
A drive circuit unit for controlling the frequency of the high-frequency current converted by the inverter circuit;
When the brightness of the discharge lamp is controlled to be changed from the first brightness to the second brightness, the output current of the resonance circuit is set to be higher than the target current for obtaining the second brightness. A dimming transition control circuit unit for controlling the frequency of the high-frequency current so that the drive circuit controls the frequency of the high-frequency current so that the drive circuit once controls the frequency of the high-frequency current and the output current of the resonance circuit becomes the target current. A discharge lamp lighting device comprising: The inverter circuit unit includes a switching element, and converts the DC voltage into a high-frequency current by switching the switching element.
The drive circuit section is
An RC circuit having a first capacitor and a second capacitor;
An integrated circuit that is connected to the RC circuit, operates at an operating frequency corresponding to the time constant of the RC circuit, and controls the frequency of the high-frequency current by switching the switching element of the inverter circuit unit by the operating frequency. With circuit,
The dimming transition control circuit unit operates the integrated circuit based on the capacitance of the first capacitor included in the RC circuit to light the discharge lamp with the first brightness, and controls the brightness of the discharge lamp. In the case of controlling the change from the first brightness to the second brightness, the integrated circuit is once operated based on the combined capacitance of the first capacitor and the second capacitor, and then the second brightness. 2. The discharge lamp lighting device according to claim 1, wherein the integrated circuit is operated based on a capacity of the capacitor to light the discharge lamp with the second brightness. 3. The RC circuit further includes a first switch connected to the first capacitor, and a second switch connected to the second capacitor,
The dimming transition control circuit unit turns on the first switch to operate the integrated circuit based on the capacitance of the first capacitor to light the discharge lamp with the first brightness. Is controlled to change from the first brightness to the second brightness, the second switch is turned on while the first switch is turned on, and the first capacitor and the second The integrated circuit is once operated based on the combined capacity with the second capacitor, and then the first switch is turned off while the second switch is turned on, and the integrated circuit is based on the capacity of the second capacitor. The discharge lamp lighting device according to claim 1, wherein a circuit is operated to light the discharge lamp with the second brightness. The dimming transition control circuit unit detects the brightness of the discharge lamp from the first brightness when detecting a predetermined operation of a power switch that controls the supply of voltage from the commercial power source to the inverter circuit unit. The discharge lamp lighting device according to any one of claims 1 to 3, wherein the change control is performed to the second brightness. 5. The dimming transition control circuit unit controls to change the brightness of the discharge lamp from the first brightness to the second brightness by using a microcomputer. The discharge lamp lighting device according to 1.

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