JPH1187075A - Electrodeless discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To relatively early start an electrodeless discharge lamp while protecting a lighting circuit, so as to make an output of light rise up of the electrodeless discharge lamp relatively early without giving excessive stress even to the circuit, in the case of starting difficult due to a high temperature in the electrodeless discharge lamp. SOLUTION: In an electrodeless discharge lamp lighting device comprising an electrodeless discharge lamp 1, induction coil 2 arranged in the vicinity thereof, high frequency power source 3, DC power source 5 serving as a power source of the high frequency power source 3, and a matching circuit 4 arranged between the high frequency power source 3 and the induction coil 2 to perform impedance matching between the both, the device has a control circuit 7, in the case that the electrodeless discharge lamp 1 is made difficult to be started due to a high temperature, stopping an output from the high frequency power source 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeless discharge lamp lighting device.

[0002]

2. Description of the Related Art A conventional electrodeless discharge lamp lighting apparatus of this type which emits light by applying a high-frequency electromagnetic field to an electrodeless discharge lamp is shown in FIG.
Shown in An electrodeless discharge lamp 1 in which a discharge gas such as an inert gas or a metal vapor is sealed in a translucent glass bulb or a glass bulb coated with a phosphor on the inner surface, and disposed in the vicinity of the electrodeless discharge lamp 1 The induction coil 2 that is connected to the induction coil 2 and supplies a high-frequency power to the induction coil 2 and supplies a high-frequency power to the induction coil 2. It comprises a matching circuit 4 for transmitting electric power, and a DC power supply 5 for converting a commercial power supply AC into a DC power supply and supplying the DC power supply to the high-frequency power supply 3.

Then, a high-frequency current of several MHz to several hundreds of MHz flows from the high-frequency power supply 3 to the induction coil 2 to generate a high-frequency electromagnetic field in the induction coil 2 and supply high-frequency power to the electrodeless discharge lamp 1. A high-frequency plasma current is generated inside to generate ultraviolet light or visible light. The frequency generated by the high-frequency power supply 3 is, for example, 13.56 MHz in the ISM band so as not to interfere with other communication devices.

[0004] By the way, when the circuit operates as described above and the starting of the electrodeless discharge lamp fails for some reason, if the starting fails, excessive stress is applied to the components constituting the circuit and the circuit is destroyed. there's a possibility that. Therefore, a protection means for protecting the circuit element in the case of failure in starting is required.

As an example of the protection means, a current flowing through the high-frequency power supply 3 is detected, and the switching element of the amplifier circuit in the high-frequency power supply 3 is stopped (short-circuiting between the gate and the source of the power MOSFET) to discharge the electrodeless electrode. There is a lamp provided with an intermittent oscillation circuit that prevents high-frequency power from being supplied to the lamp 1 and that operates the switching element intermittently and attempts to start the lamp several times.

[0006]

The reason why the electrodeless discharge lamp 1 could not be started at one time is that the electrodeless discharge lamp 1 has not been started.
In the above-described protection circuit, a high-frequency current flows through the induction coil 2 to generate heat in each of the intermittent oscillations. Therefore, the temperatures of the induction coil 2 and the electrodeless discharge lamp 1 are not easily lowered, and a considerable time is required until starting.

Accordingly, the present invention proposes an electrodeless discharge lamp lighting device in which means for cutting off the supply of high frequency power to the electrodeless discharge lamp and protecting circuit elements can be utilized more effectively. It is. Also, particularly when the electrodeless discharge lamp is a high-intensity discharge lamp, the input power to the electrodeless discharge lamp changes significantly after starting until the lamp is stabilized, and it takes a long time until the light output is stabilized, and Since it may become stable after it becomes too much, a means for making it optimally operate is also proposed.

[0008]

According to the present invention, in order to solve the above-mentioned problems, as shown in FIG. 1, an electrodeless discharge lamp 1 and an induction coil 2 arranged in the vicinity thereof are provided. A high frequency power supply 3 and a DC power supply 5 serving as a power supply for the high frequency power supply 3
And an electrodeless discharge lamp lighting device including a matching circuit 4 disposed between the high-frequency power supply 3 and the induction coil 2 and performing impedance matching between the two. In this case, a control circuit 7 for stopping the output from the high-frequency power supply 3 is provided.

[0009]

FIG. 1 shows a first embodiment of the present invention.
The DC power supply 5 includes a full-wave rectifier DB and a boost chopper circuit including an inductor L, a switching element Q, a diode D, a smoothing capacitor C, and a chopper control circuit 51. The high-frequency power supply 3 includes a pair of switching elements Q1 and Q2 each composed of a power MOSFET, a driving transformer T1, a high-frequency oscillator 31, and an inductor L.
1, the matching circuit 4 includes capacitors C2 and C3.

When the commercial power supply AC is turned on, the DC power supply 5 converts AC 100 V to DC 400 V, and the DC voltage is applied to the high frequency power supply 3. This DC voltage is converted into a high frequency voltage by the high frequency power supply 3 and supplied to the electrodeless discharge lamp 1. Here, when the electrodeless discharge lamp 1 is not started even after supplying high frequency power to the electrodeless discharge lamp 1 for a certain period of time, the temperature of the electrodeless discharge lamp 1 is detected by the temperature detecting means 6, and the cause is that the electrodeless discharge lamp 1 is at a high temperature. If it is determined that the high-frequency power supply 3
By short-circuiting between the gate and the source of the power MOSFET inside, no high-frequency power is supplied to the electrodeless discharge lamp 1. Then, the temperatures of the electrodeless discharge lamp 1 and the induction coil 2 drop relatively quickly, and when the temperature detecting means 6 detects that the temperature has dropped sufficiently, the power MOSFET is again turned on.
Is operated, the electrodeless discharge lamp 1 can be started.

FIG. 2 shows a second embodiment of the present invention. Example 1
The same parts as those described above are denoted by the same reference numerals, and redundant description will be omitted.
The difference from the first embodiment is that the DC power supply 5 is a step-down chopper circuit. In the case of this example, the power supply to the high-frequency power supply 3 is stopped by stopping the switching element Q of the DC power supply 5 by a signal from the control circuit 7. Supply is also stopped. Therefore, an effect similar to that obtained by short-circuiting the gate and source of the power MOSFET in the high-frequency power supply 3 in the first embodiment can be obtained. Other operations are the same as in the first embodiment.

FIG. 3 shows a third embodiment of the present invention. Example 1
The same parts as those described above are denoted by the same reference numerals, and redundant description will be omitted.
The difference from the first embodiment is that the temperature detection means 6 is
Is added in the vicinity of. This is to detect the temperature of the induction coil 2 indirectly by detecting the temperature of the induction coil 2 because it is difficult to directly detect the temperature of the electrodeless discharge lamp 1 at a very high temperature. The operation is the same as in the first embodiment.

FIG. 4 shows a fourth embodiment of the present invention. Example 1
The same parts as those described above are denoted by the same reference numerals, and redundant description will be omitted.
In particular, when the electrodeless discharge lamp 1 is a high-intensity discharge lamp, the input power to the electrodeless discharge lamp 1 greatly changes from starting until it is stabilized, and it takes a long time until the light output is stabilized, or conversely, There is a problem that it becomes stable after becoming too much.
In order to solve this, in the present invention, the DC power supply 5 is composed of a constant current power supply 51 and a constant voltage power supply 52. When starting the electrodeless discharge lamp 1, the constant current power supply 51 is selected. Then
For example, if the input current is smaller than the stable state immediately after the start, the control circuit 7 operates to flow a current near the stable state (that is, larger than the current state), and the light output stabilizes quickly. Conversely, when the input current becomes too large, the control circuit 7 operates to flow a current that is close to the stable state (that is, smaller than the current time). Then, when the optical output becomes substantially stable, the mode is switched to the constant voltage power supply 52, and the stable state is maintained. Here, the light output is detected using the photodetector 8, but as an alternative characteristic, control may be performed by detecting, for example, the power output from the high-frequency power supply 3. According to the present invention, the light output of the electrodeless discharge lamp 1 can be started up relatively quickly without applying excessive stress to the circuit.

[0014]

According to the present invention, when it is difficult to start the electrodeless discharge lamp due to its high temperature, the electrodeless discharge lamp can be started relatively quickly while protecting the lighting circuit. Further, the light output of the electrodeless discharge lamp can be started up relatively quickly without applying excessive stress to the circuit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is a circuit diagram according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram according to a third embodiment of the present invention.

FIG. 4 is a circuit diagram of a fourth embodiment of the present invention.

FIG. 5 is a circuit diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrodeless discharge lamp 2 Induction coil 3 High frequency power supply 4 Matching circuit 5 DC power supply 6 Temperature detection means 7 Control circuit

Claims (11)

[Claims] 1. An electrodeless discharge lamp, an induction coil disposed in the vicinity thereof, a high-frequency power supply, a DC power supply serving as a power supply for the high-frequency power supply, and disposed between the high-frequency power supply and the induction coil, In an electrodeless discharge lamp lighting device comprising a matching circuit for performing impedance matching between the two,
An electrodeless discharge lamp lighting device comprising: a control circuit for stopping output from the high-frequency power supply when the electrodeless discharge lamp is difficult to start due to high temperature. 2. The electrodeless discharge lamp lighting device according to claim 1, wherein the control circuit is configured to stop the output from the high frequency power supply and then output the output again. 3. The electrodeless discharge lamp lighting according to claim 1, wherein the high-frequency power supply has at least one switching element, and the control circuit controls the switching element of the high-frequency power supply. apparatus. 4. The high-frequency power supply and the DC power supply each have at least one switching element, and the control circuit controls each switching element of the high-frequency power supply and the DC power supply. 2
2. The electrodeless discharge lamp lighting device according to item 1. 5. The DC power supply according to claim 1, wherein the DC power supply has a switching element in series between an input and an output, and the control circuit controls the switching element of the DC power supply. Electrodeless discharge lamp lighting device. 6. The electrodeless discharge lamp lighting device according to claim 5, wherein said DC power supply is a step-down chopper circuit. 7. The lighting of an electrodeless discharge lamp according to claim 1, wherein means for detecting the temperature of the electrodeless discharge lamp is arranged near the electrodeless discharge lamp. apparatus. 8. The electrodeless discharge lamp lighting device according to claim 1, wherein means for detecting the temperature of the electrodeless discharge lamp is arranged near the induction coil. 9. The electrodeless discharge lamp according to claim 1, wherein the DC power supply functions as a constant current power supply from at least immediately after the start of the operation of the electrodeless discharge lamp until the lamp is almost stably lighted. Lighting device. 10. The high-frequency power supply comprising a constant current power supply and a constant voltage power supply, wherein the high-frequency power supply is operated by a constant current power supply from immediately after starting until substantially stable lighting is performed, and by a constant voltage power supply after substantially stable lighting. The electrodeless discharge lamp lighting device according to any one of claims 1 to 9, characterized in that: 11. The electrodeless discharge lamp lighting device according to claim 1, wherein a lighting frequency for lighting the electrodeless discharge lamp is from several MHz to several hundred MHz.