JP3387260B2 - Discharge lamp lighting device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device for lighting a discharge lamp, and more particularly to a discharge lamp lighting device for applying a high frequency electromagnetic field to an electrodeless discharge lamp to emit light.

[0002]

2. Description of the Related Art A circuit diagram of a first conventional example according to the present invention is shown in FIG.
Shown in.

A conventional discharge lamp lighting device of this kind, in which a high frequency electromagnetic field is applied to an electrodeless discharge lamp to emit light, is not provided in a transparent spherical glass bulb or a spherical glass bulb whose inner surface is coated with a phosphor. An electrodeless discharge lamp La filled with a discharge gas (for example, mercury and a rare gas) such as an active gas and a metal vapor, and a high-frequency power supply coil 1 arranged closely along the spherical outer circumference of the electrodeless discharge lamp La. (Hereinafter referred to as the induction coil 1) and an inverter circuit 2 that is connected to the induction coil 1 and supplies high frequency power to the induction coil 1.
And a matching circuit 3 composed of capacitance elements C4 and C5 for matching impedance of both the induction coil 1 and the inverter circuit 2 to eliminate reflection and efficiently transmit high frequency power to the electrodeless discharge lamp La,
A DC power supply E for applying a DC voltage to the inverter circuit 2,
A drive circuit 4 for driving the inverter circuit 2 and a starting circuit 5 for starting the inverter circuit 2 are provided. Then, a high-frequency current of several hundreds of kHz to several hundreds of MHz is passed from the inverter circuit 2 to the induction coil 1 to generate a high-frequency electromagnetic field in the induction coil 1 to supply high-frequency power to the electrodeless discharge lamp La and to generate no electrode. Discharge lamp La
A high-frequency plasma current is generated in the inside to generate ultraviolet rays or visible light.

In the inverter circuit 2, the switching elements Q1 and Q2 are connected in series and the primary winding n of the transformer T is connected.
1 is a self-excited half-bridge inverter circuit composed of an inductance element L1 and a capacitance element C3 connected in series to both ends of a switching element Q2 via a matching circuit 3 and an induction coil 1.
The AC high-frequency power is supplied to the electrodeless discharge lamp La via the resonance circuit X1.

The drive circuit 4 comprises a transformer T having secondary windings n21 and n22, and a resonance matching capacitance element C2 connected to both ends of the secondary winding n22.

The starting circuit 5 includes a resistor R1 and a capacitance element C1 connected in series at both ends of a DC power source E, and
A triac Q3 connected between a resistor R1, a contact point of the capacitance element C1 and a gate of the switching element Q2.
And a resistor R2 connected between the drain and source of the switching element Q1, a resistor R1, and a capacitance element C1.
And a diode D1 having a cathode terminal connected to the source of the switching element Q1 and a cathode terminal connected to the contact of the diode D1, and the capacitance element C1 is charged by the DC power source E via the resistor R1. When the voltage exceeds the breakover voltage of the triac Q3, the triac Q3 is turned on and a trigger voltage is applied to the gate of the switching element Q2 to activate the switching element Q2. The resistor R2
Is a bypass resistor that supplies a current to the inverter circuit 2 at the time of startup, and the diode D1 stops the triac Q3 after the startup of the inverter circuit 2.

Next, the operation will be briefly described. Before the inverter circuit 2 is started, the DC power source E charges the capacitance element C3 through the resistors R1, R2, the diode D1, the inductance element L1, and the primary winding n1 of the transformer T.
Then, when the switching element Q2 is turned on by the starting circuit 5, the inductance element L1 → the switching element Q2 is generated by the electric charge stored in the capacitance element C3.
→ primary winding n1 of transformer T → capacitance element C3
→ A current flows in the closed loop of the inductance element L1 to generate a secondary voltage in the secondary windings n21 and n22 of the transformer T, and between the secondary winding n22 of the transformer T, the capacitance element C2 and the gate / source of the switching element Q2. A second resonance circuit (hereinafter, referred to as a resonance circuit) X2 composed of the parasitic capacitance Cgs of ## EQU1 ## causes the secondary voltage to resonate to alternately turn on / off the switching elements Q1 and Q2.
An oscillating current flows through the resonance circuit X1 and the inverter circuit 2 oscillates. When the inverter circuit 2 oscillates, the electric charge charged in the capacitance element C1 is discharged through the diode D1 and the switching element Q2, and the starting circuit 5 stops its operation.

However, in the above-mentioned first conventional example, the required starting voltage value rises due to the deterioration of the characteristics of the electrodeless discharge lamp La and the mismatching of the matching circuit 3, and the low temperature starting, the dark starting, etc. are sufficient. The first problem arises that a different starting voltage may not be obtained.

As a means for solving the first problem,
There is one disclosed in JP-A-6-188091, and a circuit diagram thereof is shown in FIG. (Second Conventional Example) In this circuit, the DC power supply E is converted into an AC square wave voltage by the inverter circuit A, and high frequency power is supplied to the electrodeless discharge lamp La via the load section B including the resonance circuit X3. In an electrodeless discharge lamp lighting device for lighting an electrodeless discharge lamp La, a driving circuit for a switching element which constitutes an inverter circuit A includes a capacitance element C22, an inductance element L23,
The resonance circuit X4 including the secondary winding n21 of the transformer TR is included and configured to detect an overvoltage / overcurrent generated in the load section B, and the resonance circuit X4 detects the frequency f of the switching element.
To increase the frequency difference between the resonance frequency f0 of the resonance circuit X3 and the frequency f of the switching element to suppress the overvoltage / overcurrent generated in the load part B, and also to reduce the voltage across the induction coil by the timer circuit TC. Is gradually raised to start and light the electrodeless discharge lamp La, thereby suppressing overvoltage and overcurrent from being applied to the load section B. Then, the transistor Q20 is turned on until the electrodeless discharge lamp La is started and turned on to reduce self-induction of the resonance circuit X4, thereby increasing the frequency f of the switching element and turning on the electrodeless discharge lamp La. Transistor Q20
Is turned off to reduce the frequency f of the switching element.

[0010]

However, in the second conventional example, the voltage across the induction coil continues to rise until a voltage sufficient to start the electrodeless discharge lamp is obtained. It takes a long time, the circuit element is stressed for a long time, and the circuit element is deteriorated.
A second problem arises.

The present invention has been made in view of the above problems, and an object of the present invention is to obtain a sufficient starting voltage, to improve the startability, and to reduce the stress applied to a circuit element. It is an object of the present invention to provide a discharge lamp lighting device capable of reducing deterioration of circuit elements.

[0012]

In order to solve the above problems, according to the invention of claim 1, an electrodeless discharge lamp ,
It has at least one switching element, converts DC power into AC high-frequency power, and supplies AC high-frequency power through a first resonant circuit including at least a first inductance element and a first capacitance element.
An inverter circuit for supplying the electrodeless discharge lamp and a second resonance circuit including at least a second inductance element and a second capacitance element are provided, and the switching element is driven by the resonance operation of the second resonance circuit. In a discharge lamp lighting device having a drive circuit, the electrodeless discharge
When the lamp is started, the frequency difference between the resonance frequency of the first resonance circuit and the resonance frequency of the second resonance circuit is reduced,
Increasing the frequency difference when the electrodeless discharge lamp is turned on
A second inductance element or a front
At least one of the second capacitance elements is variable.
Characterized in that a starting aid circuit that

According to the second aspect of the present invention, the starting auxiliary circuit detects the electric power supplied to the electrodeless discharge lamp.
It is characterized in that it operates by.

[0014]

[0015]

[0016]

[0017]

According to the first aspect of the present invention, the second auxiliary element or the second capacitor is provided by the starting auxiliary circuit.
By changing the value of at least one of the stance elements,
The resonance frequency of the resonance circuit and the resonance frequency of the second resonance circuit
The resonance frequency of the second resonance circuit so that the frequency difference between
Change the number to increase the power value supplied to the electrodeless discharge lamp.
And start the electrodeless discharge lamp. Starting the electrodeless discharge lamp
After a certain time has passed from the
Of the inductance element or the second capacitance element
Resonance of the first resonance circuit by changing at least one value
The frequency difference between the frequency and the resonance frequency of the second resonance circuit is large.
The resonance frequency of the second resonance circuit is changed so that
Electrode-free discharge by reducing the power value supplied to the electrode discharge lamp
Maintain stable lighting of the lamp.

According to the invention of claim 2, electrodeless discharge
Detecting that the power supplied to the lamp has dropped below a certain value, increase the frequency difference between the resonant frequency of the first resonant circuit and the resonant frequency of the second resonant circuit, and supply it to the electrodeless discharge lamp . The power value is reduced to maintain stable lighting of the electrodeless discharge lamp .

[0019]

[0020]

[0021]

[0022]

【Example】

(Embodiment 1) A circuit diagram of a first embodiment according to the present invention is shown in FIG.

The difference from the first conventional example shown in FIG. 7 is that a series connection of inductance elements L5 and L6 is newly connected to both ends of the capacitance element C2 as an auxiliary inductor for resonance matching in the resonance circuit X2. The starting auxiliary circuit 6 is newly provided to open both ends of the inductance element L6 when starting the electrode discharge lamp La and short-circuit both ends of the inductance element L6 when starting the electrodeless discharge lamp La.
The same configurations as those of the other first conventional example are denoted by the same reference numerals and the description thereof will be omitted.

Here, in the starting auxiliary circuit 6, the series connection of the resistors R3 and R4 connected to both ends of the DC power source E and the resistor R are connected.
A smoothing capacitance element (hereinafter referred to as a capacitance element) C6 connected to both ends of the DC line 4, and a DC power source E.
A resistor R6 connected to both ends of the relay Ry, an inductor RL of the relay Ry, and a switching element Q4 connected in series, and a resistor R5 connected between the base of the switching element Q4 and the positive terminal of the capacitance element C6, and both ends of the inductor RL. And a switch Rsw of an inductor RL connected to both ends of an inductance element L6. The resistor R6 limits the current flowing through the inductor RL, and the diode D2 functions as the inductor R.
The deterioration of the element due to the back electromotive force generated in L is prevented.

Next, the operation of the starting auxiliary circuit 6 will be briefly described. When the DC power source E is turned on, the capacitance element C
6 is gradually charged from the DC power source E through the resistor R3, and the voltage across the capacitance element C6 (hereinafter referred to as DC voltage) Vc6 is up to the voltage V1 obtained by dividing the DC power source E by the resistors R3 and R4. Gradually rises. When the resonance frequency in the resonance circuit X2 at this time is fX21, the resonance frequency fX21 is the parasitic winding between the secondary winding n22 of the transformer T, the capacitance element C2, the inductance elements L5 and L6, and the gate-source of the switching element Q2. Capacity Cg
and the resonance circuit X in the conventional example shown in FIG.
It becomes smaller than the resonance frequency fX20 of 2.

When the DC voltage Vc6 reaches the ON voltage of the switching element Q4 after a lapse of a certain time after the power is turned on, the switching element Q4 is turned on, and the DC power source E causes a resistance R
6, a current flows through the inductor RL of the relay Ry via the switching element Q4, the switch Rsw is turned on, and both ends of the inductance element L6 are short-circuited. If the resonance frequency of the resonance circuit X2 at this time is fX22, the resonance frequency f
X22 becomes higher than the resonance frequency fX21, the frequency difference from the resonance frequency fX10 of the resonance circuit X1 widens, and the electric power supplied to the induction coil 1 becomes smaller, as described above. That is, since the electric power supplied to the induction coil 1 is larger when the inductance element L6 is open, the electrodeless discharge lamp La is easier to start and light up, and the induction coil 1 is shorter when the inductance element L6 is short-circuited. The supplied electric power is reduced and the electrodeless discharge lamp La is kept lit.

(Second Embodiment) A circuit diagram of a second embodiment according to the present invention is shown in FIG.

The difference from the first embodiment shown in FIG. 1 is that the inductance elements L5 and L6 are omitted, a tap is provided on the inductance element L1, and a switch R is provided between one end of the inductance element L1 and the tap of the inductance element L1.
The resonance frequency fX2 of the resonance circuit X2 is obtained by connecting sw in parallel.
Is fixed to the resonance frequency fX20, and the resonance frequency fX1 of the resonance circuit X1 is varied by the starting auxiliary circuit 6, and the same reference numerals are given to the same components as those of the other first embodiment. Omit it.

Next, the operation of the starting auxiliary circuit 6 will be briefly described. When the DC power source E is turned on, the capacitance element C
6 is gradually charged from the DC power source E via the resistor R3, and the DC voltage Vc6 gradually rises to a voltage V1 obtained by dividing the DC power source E by the resistors R3 and R4. If the resonance frequency of the resonance circuit X1 at this time is fX11, the resonance frequency f
X11 becomes smaller than the resonance frequency fX12 of the resonance circuit X1 when the electrodeless discharge lamp La is lit, and becomes close to the resonance frequency fX20.

When the DC voltage Vc6 reaches the on-voltage of the switching element Q4 after a lapse of a certain time after the power is turned on, the switching element Q4 is turned on and the DC power source E causes the resistance R
6, a current flows through the inductor RL of the relay Ry via the switching element Q4, the switch Rsw is turned on, and one end of the inductance element L1 is short-circuited. If the resonance frequency of the main circuit at this time is fX12, the resonance frequency fX
12 becomes higher than the resonance frequency fX11, the frequency difference from the resonance frequency fX20 in the drive circuit 4 widens, and the electric power supplied to the induction coil 1 decreases as described above.
That is, since the electric power supplied to the induction coil 1 is larger when the inductance element L6 is opened, the induction coil 1
Is easier to start and light up, and when the inductance element L6 is short-circuited, the electric power supplied to the induction coil 1 is smaller, and the induction coil 1 is kept on.

(Third Embodiment) FIG. 3 shows a circuit diagram of a third embodiment according to the present invention.

The difference from the first embodiment shown in FIG. 1 is that the voltage across the induction coil 1 is detected to detect the switching element Q4.
The voltage detection circuit 7 for controlling the above is provided, and the same configurations as those of the other first embodiment are denoted by the same reference numerals and the description thereof will be omitted.

Here, the voltage detection circuit 7 includes a diode D11, resistors R10 and R, which are connected to both ends of the induction coil 1.
11, a series connection of 11, a capacitance element C12 connected to both ends of the resistor R11, a comparator IC1 for comparing and outputting a voltage (hereinafter, referred to as a DC voltage) Vc12 and a reference voltage Vref across the capacitance element C12, and a comparator IC1. I
The diode D10 has an anode terminal connected to the output terminal of C1 and a cathode terminal connected to one end of a resistor R5. Next, the operation will be briefly described.

The voltage generated across the induction coil 1 after the DC power supply E is turned on is rectified by the diode D11, divided by the resistors R10 and R11, and the capacitance element C
Smoothed by 12. At the time of starting the electrodeless discharge lamp La, if the DC voltage Vc12 exceeds the reference voltage Vref,
The comparator IC1 outputs a low level (L level) signal, turns off the switching element Q4 via the diode D10 and the resistor R5, cuts off the current supplied from the DC power source E to the inductor RL, and turns off the switch Rsw. To do. Resonance operation is performed by the capacitance element C2, the secondary winding n22 of the transformer T, and the inductance elements L5 and L6. When the electrodeless discharge lamp La lights up and the voltage across the induction coil 1 drops, the DC voltage Vc12 also drops, and when the DC voltage Vc12 drops below the reference voltage Vref, the comparator I
C1 outputs a high level (H level) signal, turns on the switching element Q4 via the diode D10 and the resistor R5, supplies a current from the DC power source E to the inductor RL, and turns on the switch Rsw. Then, the resonance operation is performed by the capacitance element C2, the secondary winding n22 of the transformer T, and the inductance element L5.

By configuring as in all of the above embodiments, the power supplied to the induction coil 1 can be switched from starting to lighting more smoothly, and the stress applied to the circuit element can be improved. Can be suppressed more reliably.

In the first and third embodiments, the time from turning on the power to turning on the switching element Q4 (= time t0 to t1) is from the turning on the power to the electrodeless discharge lamp L.
It is desirable to set it to be approximately equal to the time required until the lighting of a. From the resonance frequency fX21 to the resonance frequency fX22, as shown in FIG. 4A, when the electrodeless discharge lamp La starts lighting (time t1), 4 and even if it is changed while gently drawing a curve as shown in FIG.
As shown in (c), the resonance frequency fX1 may be changed gently and linearly. The same applies to the resonance frequency fX1 in the second embodiment. Further, in all the above embodiments, the resonance frequency fX1. And fX2 may both be changed.

In the first and third embodiments, instead of the inductance elements L5, L6 and the capacitance element C2, as shown in FIG. 5, a capacitance element C10,
Connect the series connection of C11 to the gate of switching element Q2.
The resonance frequency of the drive circuit 4 may be changed from fX21 to fX by turning on the switch Rsw.
It can be increased to 22. Further, in all the above-mentioned embodiments, the resonance frequencies fX1 and fX2 may be changed by changing the values of other elements.

Further, in all of the above-mentioned embodiments, instead of the inductor RL, for example, a triac Q5 as shown in FIG. 6 or another switching element may be used, and the inverter circuit 2 may be, for example, a separately excited type or a full bridge type. Other inverter methods such as

Here, in all the above-mentioned embodiments, the capacitance element C3 is completely charged, and the current does not flow to the capacitance element C3, or the current is reduced, so that the primary windings n1 and n2 of the transformer T are reduced. Winding n2
There is a risk that the current will stop flowing in 1 and n22, or it will become smaller. In order to solve this problem, there is a method of providing a bypass resistor R8 at both ends of the capacitance element C3 as shown in FIG. 6, and by configuring in this way, the primary elements of the inductance element L1, the capacitance element C3, and the transformer T are formed. It is possible to increase the current flowing through the closed circuit composed of the winding n1. Similarly, as shown in FIG. 6, there is a method of connecting a resistor R7 in parallel to both ends of the capacitance element C4. With this configuration, the current flowing through the induction coil 1 can be increased.

[0040]

According to the first aspect of the present invention, a sufficient starting voltage can be obtained, the startability can be improved, and the stress applied to the circuit element can be reduced to reduce the deterioration of the circuit element. An electric lighting device can be provided.

According to the second aspect of the present invention, the discharge lamp can be switched from starting to lighting more smoothly, and the stress applied to the circuit element can be reduced to reduce the deterioration of the circuit element. A discharge lamp lighting device can be provided.

[0042]

[Brief description of drawings]

FIG. 1 shows a circuit diagram of a first embodiment according to the present invention.

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

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

FIG. 4 is a resonance frequency fX2 of a resonance circuit X2 according to the present invention.
Shows the change of.

FIG. 5 shows another circuit diagram of the first and third embodiments according to the present invention.

FIG. 6 shows another circuit diagram of all the embodiments according to the present invention.

FIG. 7 shows a circuit diagram of a first conventional example according to the present invention.

FIG. 8 shows a circuit diagram of a second conventional example according to the present invention.

[Explanation of symbols]

2 Inverter circuit 4 drive circuit 6 Starting auxiliary circuit C capacitance element f frequency L inductance element La discharge lamp Q switching element X resonance circuit

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) H05B 41/24

Claims (2)

(57) [Claims] 1. A first resonance circuit which has an electrodeless discharge lamp and at least one switching element, converts DC power into AC high frequency power, and comprises at least a first inductance element and a first capacitance element. An inverter circuit for supplying high-frequency AC power to the electrodeless discharge lamp via a second resonance circuit including at least a second inductance element and a second capacitance element, and the second resonance circuit. And a drive circuit for driving the switching element by the resonance operation of 1., the resonance frequency of the first resonance circuit and the resonance of the second resonance circuit at the time of starting the electrodeless discharge lamp. A frequency difference between the second inductor and a second frequency which is increased when the electrodeless discharge lamp is turned on .
At least a second element or the second capacitance element
A discharge lamp lighting device characterized in that a starting auxiliary circuit for changing one of the two is provided. 2. The starting auxiliary circuit includes the electrodeless discharge lamp.
The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device operates by detecting electric power supplied to the device.