JPH081837B2 - Electrodeless discharge lamp device - Google Patents

Description

TECHNICAL FIELD The present invention applies a high-frequency voltage to an external electrode provided outside a bulb in which a discharge gas is sealed to cause a discharge, and ultraviolet rays generated by the discharge are visible by a phosphor. The present invention relates to an electrodeless discharge lamp device used after being converted into light. BACKGROUND ART FIG. 5 shows a block diagram of an electrodeless discharge lamp device. The configuration is, for example, that a pair of external electrodes 4 made of a metal conductor is arranged near the tube end outside the bulb 3 in which a rare gas such as argon and a metal vapor such as mercury are enclosed as a discharge gas. A high-frequency voltage generated by an oscillating circuit 2 which receives power from a power source 1 is applied between the external electrodes 4 and 4 to generate a discharge in the bulb 3 to excite a metal vapor such as mercury into a metastable state. However, the ultraviolet rays (mainly in the case of mercury, the wavelengths of 253.7 nm and 184.9 nm) emitted when these metal vapors relax to the ground state are visible by the phosphor (not shown) coated inside the bulb 3. It is converted into light and used as a light source for illumination or a light source for display. FIG. 6 shows an example of a specific circuit of the conventional oscillator circuit 2, the basic configuration of which is a clap circuit with a stable oscillation frequency. The operation of the electrodeless discharge lamp device will be described below with reference to FIG. In the oscillator circuit 2 shown in FIG. 6, a bipolar transistor is used as the oscillator circuit Q ₁ , but it goes without saying that another active element such as a MOSFET may be used. Rectification of the AC voltage of the power supply 1 by a diode bridge DB (not shown) to smooth the pulsating voltage
DC power supply E is configured by smoothing with C ₀ , and its terminal voltage is
The voltage is divided by R ₁ and R ₂ and a resistor R _{3 is} added to the base B of the oscillator Q _1.
When an appropriate bias voltage Vb is applied via the collector current I _C , the oscillating element Q ₁ acts as an amplifier. However, since a part of the oscillation output is fed back to the input side by the resonance circuit consisting of the oscillation coil L ₁ and the capacitors C ₁ , C ₂ , and C ₃ , it can be sustained if the value of the above circuit constant is properly selected. Start oscillating. The oscillation output of the oscillation circuit 2 is supplied to the bulb 3 of the electrodeless discharge lamp by connecting the external electrodes 4, 4 to both ends of the oscillation coil L ₁ . Therefore, in the bulb 3 of the electrodeless discharge lamp, the discharge gas starts the discharge to excite the mercury atoms into a metastable state, and the ultraviolet rays emitted when the mercury atoms relax to the ground state are applied to the inner wall surface of the bulb 3. It is converted into visible light by the phosphor coated on. As is clear from the above description, the emission color of the electrodeless discharge lamp is uniquely determined by the kind of the phosphor applied to the inner wall surface of the bulb 3, and in the conventional electrodeless discharge lamp,
Since the phosphor is composed of only one type, the emission color cannot be changed, and there is a problem that a plurality of electrodeless discharge lamps having different emission colors are required to obtain different emission colors. there were. [Object of the Invention] The present invention has been made in view of the above problems,
An object of the present invention is to provide an electrodeless discharge lamp device capable of freely changing the emission color. DISCLOSURE OF THE INVENTION An electrodeless discharge lamp device of the present invention includes an oscillation circuit that receives power from a power source to generate a high-frequency voltage, a valve in which a metal gas such as rare gas or mercury is sealed as a discharge gas, and At least a pair of external electrodes provided externally, the high-frequency voltage is applied between the external electrodes to cause discharge in the bulb, and ultraviolet rays generated by the discharge are applied to the inner wall surface of the bulb. In an electrodeless discharge lamp device that converts visible light with a fluorescent substance, two or more types of fluorescent substances with different emission colors are applied to the inner wall surface of the bulb, and the high frequency potential of each of the pair of external electrodes is relatively The oscillating circuit is provided with a light emission center moving means for changing the position of the light emission center in the bulb.

Embodiment 1 FIG. 1 shows a bulb 3 of an electrodeless discharge lamp according to an embodiment of the present invention.
3A and 3B illustrate the configuration of the external electrodes 4a and 4b. On the inner wall surface of the bulb 3, a phosphor R of red emission color is applied to the right half and a phosphor G of green emission color is applied to the left half. FIG. 2 is a circuit diagram of an oscillator circuit 2 according to an embodiment of the present invention, which is a Clap type oscillator circuit as in the conventional example. However, in an oscillator circuit in a city, for example, a Hartley type or a Colbitts type oscillator circuit. However, the description is omitted because it is the same. The bias circuit of this embodiment is a DC power source E.
Resistor connected to (hereinafter, terminal voltage value is also indicated by E)
The midpoint of the series circuit of R ₁ and R ₂ and the base B of the oscillating element Q _{1 formed} of a bipolar transistor are connected by a resistor R ₃ . The resistor R ₃ supplies the voltage of the DC power source E divided by the resistors R ₁ and R ₂ to the base B of the oscillating element Q ₁ as the bias voltage Vb, and the high frequency current is applied to the resistors R ₁ and R _{2 of the} bias circuit. Is blocked by the resistor R ₃
An inductance may be used instead of. Further, the resonance circuit of the present embodiment has an oscillation coil L ₁ and capacitors C ₂ , C
₃ and oscillation coils L ₁ at both ends are connected in series to the two variable capacitors Ca, it is composed of a Cb, the oscillation coil L ₁
The external electrode 4a is connected to the terminal to which the capacitor Ca of
However, the external electrode 4a is connected to the terminal to which the capacitor Cb is connected. And the variable capacitor C
The capacitances of a and Cb change in conjunction with each other.
If the capacitance of Ca is increased, the capacitance of the variable capacitor Cb is reduced accordingly. Conversely, if the capacitance of the variable capacitor Ca is reduced, the capacitance of the variable capacitor Cb is increased accordingly. It is configured to change with. The variable capacitors Ca and Cb correspond to the light emission center moving means. When the voltage of the power supply 1 is applied and the oscillation circuit 2 starts to oscillate, a discharge is generated inside the bulb 3 of the electrodeless discharge lamp, and the ultraviolet rays are emitted as described above. Half emits red light, and the left half emits green light. However, the relative intensity of the above two emission colors changes depending on the size relationship of the capacitances of the variable capacitors Ca and Cb. The description will be given below. First, the problem is the high-frequency potential, so the discussion is limited to a closed circuit consisting of capacitor C ₂ → variable capacitor Ca → oscillation coil L ₁ → variable capacitor Cb → capacitor C ₃ → capacitor C ₂ . In addition, capacitor C ₂ and capacitor
The value of C ₃ shall be designed so that each order is similar. Now, assuming that the value of the variable capacitor Ca is set smaller than the value of the variable capacitor Cb, the high-frequency impedance of the series circuit of the capacitor C ₂ and the variable capacitor Ca is the series impedance of the capacitor C ₃ and the variable capacitor Cb. Since it becomes larger than the high frequency impedance of the circuit, the high frequency potential of the external electrode 4a becomes higher than the high frequency potential of the external electrode 4b. That is, in this case, since the external electrode 4a is a hot terminal and the external electrode 4b is a cold terminal, the light emitting state of the bulb 3 is brightest in the vicinity of the external electrode 4a which is a hot terminal, and the brightness becomes closer to the external electrode 4b. Decreases, and the vicinity of the external electrode 4b, which serves as a cold terminal, becomes darkest. As described above, the phenomenon that the brightness gradient is generated inside the bulb 3 is caused by a stray capacitance existing between the bulb 3 and the ground and a loop formed by the discharge path inside the bulb 3 from a hot terminal. This is because a part of the high-frequency current flowing in the cold terminal is gradually shunted. Contrary to the above case, change the capacitance of the variable capacitors Ca and Cb to C
When a> Cb, the external electrode 4a serves as a cold terminal and the external electrode 4b serves as a hot terminal, and the above-mentioned light emitting state is also reversed. Further, when the capacitances of the variable capacitors Ca and Cb are made substantially equal, as described above, the capacitors C ₂ and C ₃
Since the capacitance values of are equal to each other in order, the high frequency potential difference between the external electrode 4a and the external electrode 4b almost disappears, and the luminance distribution inside the bulb 3 becomes substantially uniform. As is clear from the above description, in the electrodeless discharge lamp device having the configuration of the present embodiment, the capacitance of the variable capacitors Ca and Cb provided as the light emission center moving means is changed to change the bulb 3 of the electrodeless discharge lamp. The internal brightness distribution is made uniform, or an appropriate brightness gradient is provided between the external electrode 4a and the external electrode 4b. In an extreme case, the external electrode 4a is used.
Alternatively, the position of the light emission center can be variously changed such that only the vicinity of the external electrode 4b can emit light. Therefore, if two or more kinds of phosphors having different emission colors are applied to the inner wall surface of the bulb 3 at different positions, the emission color of the entire bulb 3 is applied by moving the position of the emission center. Any one of the phosphors or a mixed color of several kinds can be used. That is, in the present embodiment, it is possible to obtain light emission of any one of green and red and a mixed color thereof. Although the circuit using the variable capacitors Ca and Cb as the light emission center moving means is shown in this embodiment, any circuit can be used as long as it can relatively change the value of the high frequency potential inside the bulb 3. It doesn't matter.

Second Embodiment FIG. 3 shows an electrodeless discharge lamp device according to another embodiment of the present invention. The oscillator circuit 2 of this embodiment is similar to the circuit of the first embodiment shown in FIG. 1, and the difference from the first embodiment is that the valve 3 is used.
The point is that a diffusion globe 5 that covers the whole is provided, and the structure of the bulb 3 that serves as a light emitting portion. That is, the shape of the bulb 3 of the electrodeless discharge lamp of the present embodiment is not the straight tube shape shown in the first embodiment, but is substantially U-shaped, and the phosphor R having a red emission color is formed in the central portion on the inner wall surface. The green and blue phosphors G and B are applied to both ends sandwiching the phosphor, respectively. Further, the light emitted from the bulb 3 is diffused and mixed by the diffusion globe 5, and the light emitted from the bulb 3 serving as a light source is prevented from directly entering the eyes to reduce glare. The values of the variable capacitors Ca and Cb are obtained by applying the high frequency voltage of the oscillation circuit 2 described in the first embodiment to the external electrodes 4a and 4b (not shown) at both ends of the bulb 3 of the electrodeless discharge lamp having the above configuration. Can be changed in various ways such as blue, green, or yellow, which is a mixed color of these lights.

[Embodiment 3] FIG. 4 shows a block diagram of still another embodiment of the present invention.
The difference from the electrodeless discharge lamp device of the second embodiment shown in FIG. 3 is that the bulb 3 covered by the diffusion globe 5 has phosphors R, G, B of different emission colors on the inner wall surface. The three U-shaped tubes coated with are alternately arranged in the opposite direction, and the starting point and the end point are connected so that they are arranged next to each other.
With the above-mentioned structure, the inner wall surfaces are coated with phosphors of different emission colors, and the three U-shaped tubes are fused together, so that the inner wall surfaces are coated with phosphors of different emission colors. Since one valve 3 can be manufactured, the method for manufacturing the valve 3 is easy. Further, as described in the second embodiment, the effect of the diffusion globe 5 makes it possible to make the above-mentioned respective colors, that is, the brightness of blue, red, and green, substantially the same, and to utilize the same for display illumination and the like. is there. [Advantages of the Invention] In the electrodeless discharge lamp device of the present invention, a high-frequency voltage is applied between the external electrodes to cause discharge in the bulb, and ultraviolet rays generated by the discharge are applied to the inner wall surface of the bulb. In an electrodeless discharge lamp device that converts visible light by the body, two or more types of phosphors having different emission colors are applied to the inner wall surface of the bulb, and the high-frequency potential of each of the pair of external electrodes is relatively Since the oscillation circuit is provided with the light emission center moving means for changing and moving the light emission center position in the bulb, it is possible to change the position of the light emission center to cause the phosphors of different emission colors to emit light. Due to
Since the variable color fluorescent lamp that can change the emission color can be configured with only one bulb, it is possible to provide a compact and lightweight variable color fluorescent lamp at low cost, and there is no electrode inside the bulb. Therefore, not only the electrode is not worn by ions but also has a long flashing life, and the luminous flux is not reduced in the vicinity of the electrode, so that an ideal characteristic as a display device can be provided.

[Brief description of drawings]

FIG. 1 is a side view of the vicinity of the valve according to the first embodiment of the present invention, and FIG.
FIG. 3 is a circuit diagram of the electrodeless discharge lamp device according to the first embodiment of the above, FIG.
FIG. 4 is a block diagram of the second embodiment, and FIG. 4 is a third embodiment of the same.
FIG. 5, FIG. 5 is a block diagram of a conventional example, and FIG. 6 is a circuit diagram of a conventional electrodeless discharge lamp device. 1 is a power supply, 2 is an oscillation circuit, 3 is a bulb, and 4a and 4b are external. Electrodes, 5 are diffusion gloves, Ca and Cb are variable capacitors, R, G and B are red and green respectively.
It is a phosphor of blue emission color.

Claims (1)

[Claims] 1. An oscillating circuit which receives a power supply from a power source to generate a high frequency voltage, a valve in which a metal vapor such as a rare gas or mercury is sealed as a discharge gas, and at least a pair of external electrodes provided outside the valve. And applying the high-frequency voltage between the external electrodes to cause discharge in the bulb, and converting ultraviolet rays generated by the discharge into visible light by the phosphor coated on the inner wall surface of the bulb. In the electrode discharge lamp device, two or more kinds of phosphors having different emission colors are applied to the inner wall surface of the bulb, and the high frequency potential of each of the pair of outer electrodes is relatively changed to cause the light emission in the bulb. An electrodeless discharge lamp device, wherein the oscillation circuit is provided with a light emission center moving means for moving the center position.