JPH0640486B2 - Electrodeless discharge lamp device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention encloses a gas body such as a rare gas or a metal vapor in a translucent valve, and applies a high frequency voltage to a coil wound outside the valve. To discharge the gas inside the valve,
The present invention relates to a so-called electrodeless discharge lamp device, which uses the emitted light or the generated ultraviolet light after being converted into visible light by a fluorescent substance applied to the inner wall of the bulb.

[Prior Art] The applicant of the present application has previously applied for an electrodeless discharge lamp device for the purpose of uniform light emission over the entire area of the lamp (Japanese Patent Application No. 62-12).
7601).

FIG. 3 shows an example of the electrodeless discharge lamp device according to FIG.
In the lamp 1, two straight tubes 2 and 2 are arranged in parallel with each other, and both ends of each straight tube 2 are connected via a bridge 3 to form one orbiting discharge path as a space inside the lamp. An induction coil 4 is arranged outside the lamp 1 and along the circulating discharge path. The lamp 1 is filled with a rare gas such as argon or a metal such as mercury in addition to the rare gas as a gas body.

With this configuration, when a high-frequency current flows through the coil 4 in the direction of the arrow in the drawing, the induced current Ia that flows in the lamp 1 due to the high-frequency current flows so as to form a loop in the lamp 1. Even if the voltage is lowered, the induced current does not form another short-circuited loop, but continuously maintains the loop along the coil 4, and uniform light emission is maintained throughout the lamp.

However, such an electrodeless discharge lamp device still has a problem. FIG. 4 is a view of FIG. 3 seen from the upper side. When the lamp 1 is turned on in such a device, a so-called blackening phenomenon occurs on the inner surface of the lamp 1. This is mainly due to the formation of a compound of mercury enclosed in the lamp 1 and impurities remaining in the lamp 1, and such a phenomenon is caused by the discharge plasma in the lamp 1 and the induction coil 4. It is considered that this is due to the electric field coupling through the lamp bulb 2. Since such a blackening phenomenon naturally blocks the light emitted to the outside, it causes a large decrease in the amount of light and shortens the lamp life.

As a means for preventing such blackening, a device as shown in FIG. 5 can be considered. That is, the valve 2 and the coil 4
And an electrostatic shield body 5 made of a dielectric material is disposed between and. When the electrostatic shield body 5 is provided in an endless belt shape over the entire circumference of the lamp 1, a current flows by electromagnetic induction along the circumferential direction of the induction coil 4, and electromagnetic induction does not occur in the bulb 2. Electrical insulation must be provided in at least one of the locations. In this example, the electrostatic shield body 5 is insulated by providing a cut portion 6 in a part thereof. Further, it is desirable that the electrostatic shield body 5 be grounded at any one place. It is considered that by providing the electrostatic shield body 5 in this way, the electric field coupling between the induction coil 4 and the lamp 1 is weakened, and the blackening due to this is reduced.

However, according to such a device, although blackening that occurs in the lamp 1 is prevented and the lamp life is improved, the presence of the electrostatic shield 5 causes the induction coil 4 to supply high-frequency energy to the lamp 1. Becomes insufficient,
There arises a new problem that the initial light amount is reduced.

[Problems to be Solved by the Invention] The present invention has been made in view of the above problems, and an object of the present invention is to uniformly emit light over the entire area of a lamp and prevent a decrease in light amount due to blackening of the lamp. An object of the present invention is to provide an electrodeless discharge lamp device capable of preventing a decrease in light quantity.

[Means for Solving the Problems] The present invention relates to an electrodeless discharge in which a gas body enclosed in the bulb is discharged and emits light by applying a high-frequency voltage to a coil wound outside the translucent bulb. In the electric light device, the bulb is constituted by a bulb having at least two straight pipe portions that are parallel to each other, and communicating with each other near both ends of the straight pipe portion to form a circulating discharge path. Is disposed along the orbiting discharge path, and between the outer circumference of the valve forming the orbiting discharge path and the coil, and in a substantially half-circumferential area centered around the feeding point of the coil, It is characterized in that an electrostatic shield body composed of a body is provided.

Hereinafter, the present invention will be described based on examples. FIG. 1 shows an embodiment of the present invention. The difference from the configuration shown in FIG. 5 is that the electrostatic shield body 5 is limited to a region relatively close to the feeding points a and h of the induction coil 4. Since the other configurations are the same as those of the conventional example by providing the same, the description thereof will be omitted by assigning the same reference numerals to the same configurations.

The reason why the region where the electrostatic shield body 5 is provided is limited is as follows. The present inventors have made various studies on the blackening that occurs in such a device, and have found a certain relationship between the blackening occurrence point in the lamp 1 and the induction coil 4. That is, it was found that the blackening occurred mainly in the vicinity of the feeding point of the induction coil 4 and the intensity of the blackening gradually decreased as the distance from the blackening point increased.

The cause is considered as follows. That is, the ground potential at each point on the circulating induction coil 4 causes a potential difference due to the impedance of the induction coil 4 itself. Therefore, on the outer circumference of the valve 2, reference characters b and g in FIG.
The potentials at the two points shown by are maximized, and the potentials become lower as the distance from the feeding points a and h increases, such as points b → c → d and points h → f → e. The degree of occurrence of blackening at each position of the lamp 1 affects the height of the electric potential at each point of the induction coil 4 corresponding to that position, and therefore the position corresponding to the points b and g having the highest electric potential. Blackening is most noticeable. Actually, the blackening hardly occurs on the entire circumference of the lamp 1, and is concentrated near the feeding point of the induction coil 4.

On the other hand, the addition of the electrostatic shield body 5 causes a decrease in the initial light amount of the lamp, but is rapidly improved as the non-installed region of the shield body 5 is increased, and the length of the shield body 5 is reduced by the lamp 1.
If it is shortened to about half of the total circumference, the initial light intensity will be 5
It has been confirmed by the experiments by the present inventors that the level of recovery is almost the same as in the case of not applying the method.

Therefore, according to the present invention, since the electrostatic shield body 5 is installed only in the region where blackening is likely to occur, the initial light amount does not decrease due to the installation of the shield body 5, and
It is possible to provide an electrodeless discharge lamp device in which the life of the lamp is improved because the decrease in the amount of light due to blackening is small.

In the present invention, the position of the feeding point of the induction coil 4 is not limited to the above embodiment, but may be set to another position depending on the design of the device, for example, as shown in FIG. It may be configured as follows. In this case, of course,
Since the region where blackening is likely to occur also changes, the electrostatic shield body 5 may be installed in a region corresponding to this. Further, the coil 4 is not limited to the linear shape having a circular cross section, and may be, for example, a tape shape.

Further, generally, in the lighting system in which the induction coil 4 is circulated around the outer periphery of the lamp 1 to discharge, which is the basis of the present invention, the inductance L of the coil 4 is reduced.
And a resonance frequency determined by the capacitance C _{1 of} a capacitor (not shown) connected to the coil 4. However, as in the present invention, the lamp 1
When the electrostatic shield body 5 made of a conductor is provided between the coil 4 and the coil 4, a capacitor having a capacitance C ₂ is equivalently formed between the coil 4 and the electrostatic shield body 5 in parallel with the capacitor C _1. To be done. Therefore, the capacitor of the capacitance C ₁ is
Since C ₁ ′ = C ₁ −C ₂ (C ₁ > C ₂ ), the capacitance of the capacitor to be connected can be reduced.

[Advantages of the Invention] As described above, according to the present invention, by applying a high-frequency voltage to a coil wound outside the translucent bulb, the gas body enclosed in the bulb is discharged and emits no electrode. In the electric light device, the bulb is constituted by a bulb having at least two straight pipe portions that are parallel to each other, and communicating with each other near both ends of the straight pipe portion to form a circulating discharge path. Is disposed along the circulating discharge path, and when such a discharge lamp device is lit, a region where most of the blackening products generated on the inner surface of the bulb are concentrated, that is, the coil The electrostatic shield body made of a conductor is provided between the outer circumference of the bulb and the coil, and the light is emitted uniformly over the entire area of the lamp. In addition, it was possible to provide an electrodeless discharge lamp device capable of preventing a decrease in light amount due to blackening of the lamp and further preventing a decrease in initial light amount due to addition of a shield body.

[Brief description of drawings]

1 is a top view showing an embodiment of the present invention, FIG. 2 is a top view showing another embodiment of the present invention, FIG. 3 is a perspective view showing a conventional example, FIG. 4 is a top view showing the same, FIG. 5 is a top view showing a different conventional example. 1 ... Lamp, 2 ... Bulb, 4 ... Coil, 5 ... Electrostatic shield.

Claims (1)

[Claims] 1. An electrodeless discharge lamp device in which a gas body enclosed in the bulb is discharged and emits light by applying a high-frequency voltage to a coil wound outside the translucent bulb. The valve has at least two straight pipe portions that are parallel to each other, and is formed of a valve that communicates near both ends of the straight pipe portion to form a circulating discharge path, and the coil is provided along the circulating discharge path. An electrostatic shield body made of a conductor is provided between the outer circumference of the bulb which forms the circulating discharge path and the coil, and a substantially half-circumference centered around the feeding point of the coil. An electrodeless discharge lamp device characterized by being provided.