JPH11297278A - Rare gas discharge lamp and lighting device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rare gas discharge lamp capable of easily and surely performing dimming stepwise and reducing the lighting voltage, and a lighting device thereof. SOLUTION: This lighting device is provided with a rare gas discharge lamp 1 comprising a cylindrical envelop 2 having a rare gas sealed therein, a light emitting layer 3 formed on the inner surface of the envelope 2, a bar-like internal electrode 5 fixed and arranged in the internal center of the envelop 2 extending over the whole length of the envelop 2, and a plurality of external electrodes 6a-6b fixed and arranged in a plurality of positions on the circumferential surface of the envelop 2 at equal intervals; and a high frequency voltage generating circuit 7 for generating a high frequency voltage. The high frequency voltage generated in the high frequency voltage generating circuit 7 is applied to the internal electrode 5 and one selected from the external electrodes of the rare gas discharge lamp to light the rare gas discharge lamp.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rare gas discharge lamp and a lighting device therefor, and more particularly to a dimmable lamp by selectively applying a high-frequency voltage to a plurality of external electrodes provided on the outer surface of an envelope. To improved rare gas discharge lamps and their lighting devices.

[0002]

2. Description of the Related Art In a conventional rare gas discharge lamp of this type, for example, a rare gas is sealed in a straight tubular envelope in which a light emitting layer having an aperture portion (a portion where no light emitting layer is formed) is formed on the inner surface. At the same time, a pair of band-shaped external electrodes are formed on the outer peripheral surface of the envelope so as to be separated from each other over the longitudinal direction of the envelope.

In this rare gas discharge lamp, a high-frequency high voltage (for example, a frequency of 30 KHz and a voltage of 25
00V _OP ). That is, when a high-frequency high voltage is applied, countless discharge paths are formed in the envelope between the pair of external electrodes in a direction substantially perpendicular to the longitudinal direction of the envelope, and the rare gas is excited by this discharge. The light emitting layer is excited by the line (ultraviolet light), and visible light is emitted from the light emitting layer. Light from the light emitting layer is projected to the outside from an aperture portion provided over the entire length of the envelope.

The rare gas discharge lamp has a feature that it is suitable as a light source for reading originals of OA equipment such as a copying machine and an image scanner because the light amount reaches almost 100% at the same time as the lighting. In recent years, in OA equipment and other applications, there has been a demand for varying the amount of light, but it is difficult to achieve satisfactory dimming due to a unique discharge.

[0005]

In order to solve such a problem, for example, Japanese Patent Application Laid-Open No. Hei 5-242870 discloses that a plurality of pairs of external electrodes are formed on an outer peripheral surface of an envelope in which a rare gas is sealed. There is disclosed a rare gas discharge lamp configured to selectively apply a high frequency and high voltage to a plurality of pairs of external electrodes. A specific example is shown in FIG. 6 and described.

The rare gas discharge lamp 11 shown in FIG. 6 has, for example, an aperture in which three pairs of strip-shaped external electrodes 15a to 15f are formed on the outer peripheral surface of a straight tubular envelope 12 which is hermetically sealed by a glass bulb. Type discharge lamp. A light-emitting layer 13 made of a phosphor such as a rare-earth phosphor having an aperture portion 14 is formed on the inner peripheral surface of the envelope 12, and a rare gas mainly composed of xenon is sealed in the enclosed space of the envelope 12. Have been. On the outer peripheral surface of the envelope 12, strip-shaped external electrodes 15 a to 15 f having the same length as the entire length of the envelope 12 are formed apart from each other, except for the aperture portion 14. The external electrodes 15a to 15f are connected to a high-frequency power supply 16 for generating a high-frequency high voltage via switches 17a to 17f.

The rare gas discharge lamp 11 includes a high frequency power supply 16
Lights up as follows. When the light is turned on at 100% of the rated light, all the switches 17a to 17f are turned on and all three pairs of external electrodes 15a and 15f, 15b and 15
e, 15c and 15d to a high-frequency high voltage (several 10~50KH _Z, 500~1000V) of the high frequency power source 16 applies a. By applying the high frequency high voltage, the envelope 1 which is a dielectric
A discharge path is formed in almost the entire region of the rare gas space of the envelope 12 via the glass wall of No. 2, and the light emitting layer 13 is excited by the excitation line of the rare gas due to the discharge, thereby emitting visible light. Light from 13 is intensively projected from the aperture section 14 to the outside.

In the case where the rare gas discharge lamp 11 is illuminated by dimming the amount of light to １ ／, for example, a pair of switches 1
Only 7c and 17d are turned on and a pair of external electrodes 15c and 1
When a high-frequency high voltage is applied only to 5d, a discharge is generated only in approximately one third of the lower part of the envelope 12, and light that has been dimmed to one third from the light emitting layer 13 in this portion is transmitted to the aperture part 14.
Is released to the outside.

However, this rare gas discharge lamp 11
By selectively applying a high-frequency high voltage to a plurality of pairs of external electrodes formed on the outer peripheral surface of the envelope, dimming can be performed step by step, but for the purpose of securing predetermined starting characteristics, Since a high-frequency high voltage must be applied to any of the external electrodes, there is a problem in that the apparatus becomes expensive because lighting circuit elements such as a transformer in the high-frequency power supply 16 require high withstand voltage measures.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a rare gas discharge lamp capable of performing dimming in a simple and reliable manner in a stepwise manner and capable of lowering a lighting voltage, and a lighting device therefor.

[0011]

According to the present invention, there is provided a rare gas discharge lamp for achieving the above object, comprising a cylindrical envelope in which a rare gas is sealed, and a light emitting layer formed on the inner surface of the envelope. A rod-shaped internal electrode fixedly arranged over the entire length of the envelope at the center of the interior of the envelope, and a plurality of external electrodes fixedly arranged at a plurality of locations on the outer peripheral surface of the envelope. It is characterized in that it has a structured structure.

Here, the internal electrode disposed in the envelope is a single rod-shaped electrode common to a plurality of external electrodes formed on the outer periphery of the envelope, and both ends thereof are cylindrical envelopes. Is sealed and fixed to both ends. Further, the plurality of external electrodes are separated from each other in the circumferential direction of the outer peripheral surface of the cylindrical envelope, or are separated from each other in the longitudinal direction of the outer peripheral surface of the cylindrical envelope. It is formed. By applying a high-frequency voltage to such a common internal electrode and a selected external electrode among a plurality of external electrodes, the rare gas discharge lamp is lit and lit. This lighting is performed by a discharge of a short rare gas space between the inner electrode located at the center in the envelope and the outer electrode on the outer peripheral surface of the envelope (between the radius of the envelope). Reduced.

A second invention of the present invention is directed to a cylindrical envelope enclosing a rare gas, a light-emitting layer formed on the inner surface of the envelope, and an envelope at the center of the interior of the envelope. A rare gas discharge lamp having a rod-shaped internal electrode fixedly arranged over the entire length, a plurality of external electrodes fixedly arranged at a plurality of locations on the outer peripheral surface of the envelope, and a high-frequency voltage for generating a high-frequency voltage And a high-frequency voltage generated by the high-frequency voltage generation circuit is applied to an internal electrode of the rare gas discharge lamp and a selected external electrode among the plurality of external electrodes to light the rare gas discharge lamp. It is characterized by the following.

According to a third aspect of the present invention, the internal electrode of the rare gas discharge lamp is grounded.
A fourth invention is characterized in that the high-frequency voltage generation circuit is a pulse generation circuit that generates a high-frequency pulse. As described above, the efficiency is improved by lighting the rare gas discharge lamp with the high frequency pulse of the pulse generation circuit.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rare gas discharge lamp and a lighting device thereof according to the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of a rare gas discharge lamp 1 according to an embodiment of the present invention, and a block diagram of a high-frequency voltage generating circuit 7 for lighting the rare gas discharge lamp 1. Rare gas discharge lamp 1
Comprises a cylindrical envelope 2 made of a glass bulb filled with a rare gas. A light emitting layer 3 made of a phosphor such as a rare earth phosphor is formed on the inner surface of the envelope 2, and a part of the envelope 2 in the longitudinal direction where the light emitting layer 3 is not formed is formed as an aperture portion 4. A single rod-shaped internal electrode 5 is fixed along the inner center line of the envelope 2, and a plurality of external electrodes 6 a to 6 e are formed at a plurality of positions in the circumferential direction of the outer peripheral surface of the envelope 2 so as to be separated from each other. Is done. A single rare gas such as xenon, krypton, or neon, which does not contain metal vapor, is contained in the enclosed space in the envelope 2.
Alternatively, they are mixed and sealed.

The single rod-shaped internal electrode 5 has a length equal to or longer than the entire length of the cylindrical envelope 2, for example, and is disposed substantially at the center of the interior of the envelope 2 as shown in FIG. Both ends are sealed and fixed at the center of both end walls of the envelope 2. The plurality of external electrodes 6 a to 6 e are, for example, as shown in FIG. 3A, band-shaped electrodes elongated in the longitudinal direction of the envelope 2 and have the same width,
Those having a length are fixed to the outer peripheral surface of the envelope 2 except for the aperture section 4 at equal intervals so as to be spaced apart from each other in the circumferential direction. The number of the external electrodes 6a to 6e shown in FIG. 1 is 5, and hereinafter, the first external electrodes 6a to 6e are only used for distinguishing the five external electrodes 6a to 6e.
An external electrode 6a, a second external electrode 6b, a third external electrode 6c,
They are referred to as a fourth external electrode 6d and a fifth external electrode 6e.

One internal electrode 5 is commonly used for each of the external electrodes (6a to 6e), and this common internal electrode 5 is connected to the high-frequency voltage generating circuit 7, and each of the external electrodes (6a to 6e) is used.
e) is connected to the high-frequency voltage generating circuit 7 via the switches 8a to 8e. The high-frequency voltage generation circuit 7 generates a high-frequency voltage for lighting the rare gas discharge lamp 1 with a desired brightness. The high-frequency voltage generated here is applied to the selected one of the internal electrode 5 and the plurality of external electrodes 6a to 6e by turning on and off the switches 8a to 8e, and the rare gas discharge lamp 1 is adjusted as follows. It is lit and lit.

When the rare gas discharge lamp 1 is lit in the all-light state (100% light amount), all the switches 8a to 8f are turned on and the high frequency voltage is applied to the internal electrode 5 and all the external electrodes (6a to 6e). The high frequency voltage of the generating circuit 7 is applied. At this time, discharge occurs in the rare gas space between the internal electrode 5 and the first external electrode 6a, and similarly, discharge occurs in each rare gas space between the internal electrode 5 and the second to fifth external electrodes 6b to 6e. The light-emitting layer 3 emits light as a result and discharges in the entire inner space of the envelope 2 as a result. Light from the light emitting layer 3 is emitted to the outside from the aperture section 4 in an all-light state.

Here, the discharge distance between the internal electrode 5 and the first external electrode 6a is half the diameter of the cylindrical envelope 2, and the internal electrode 5 and the first external electrode 6a In between,
Since there is only one glass wall of the glass bulb to which the first outer electrode 6a is fixed, the inner electrode 5 and the first
The distribution voltage of the glass wall occupying the applied voltage of the external electrode 6a is almost half that in the case of FIG. Therefore, the lighting voltage for generating a discharge between the internal electrode 5 and the first external electrode 6a is significantly lower than that of the rare gas discharge lamp shown in FIG. This lowering of the lighting voltage is the same between the common internal electrode 5 and the other second to fifth external electrodes 6b to 6e. Such lowering of the lighting voltage makes it possible to simplify the circuit configuration of the high-frequency voltage generating circuit 7, measures against high breakdown voltage, and the like, and to reduce the cost of the apparatus.

In the case where the rare gas discharge lamp 1 is illuminated by dimming the light amount to 1/5 of the total light, for example, the first external electrode 6
Only the switch 8a is turned on, and a high-frequency voltage is applied only to the internal electrode 5 and the first external electrode 6a. Then, a discharge is generated only in the rare gas space between the internal electrode 5 and the first external electrode 6a, and the rare gas discharge lamp 1 is turned on with approximately 1/5 of the total light.

When the rare gas discharge lamp 1 is to be lit by dimming to a light amount of 4/5, for example, only the switch 8a of the first external electrode 6a is turned off, and the other switches 8b to 8e are turned on. Internal electrode 5 and second to fifth external electrodes 6b to 6e
Is applied with a high-frequency voltage. Then, the internal electrode 5 and the second to second
A discharge is generated in the rare gas space between the fifth external electrodes 6b to 6e, and the rare gas discharge lamp 1 is turned on with approximately 4/5 of the total light.

In the rare gas discharge lamp 1 described above, the common one
It is desirable to ground the internal electrodes 5 of the book. That is, by grounding the internal electrode 5, the discharge is stabilized and flicker can be suppressed.

The high-frequency voltage generating circuit 7 can turn on the rare gas discharge lamp 1 even with a sine-wave high-frequency voltage. In this case, the lamp current flows in a pulsed manner at the peak value of the sine-wave to light the lamp. Power is wasted. Therefore,
The high-frequency voltage generation circuit 7 is preferably a pulse generation circuit for lighting the rare gas discharge lamp 1 with high-frequency pulses, and specific examples will be described with reference to the pulse generation circuit 7 in FIG. 4 and the waveform diagrams in FIG.

The pulse generation circuit 7 shown in FIG. 4 includes an inverter circuit H for generating a high-frequency voltage, an oscillation transformer TRA having a primary coil TRa and a secondary coil TRb, and a capacitor C.
And the switching element Q, and operates as follows. First, a DC power supply that is full-wave rectified from a commercial power supply is connected to terminals T ₁ and T ₂ at both ends of the capacitor C, and the capacitor C is charged with the DC power supply. By turning on the switching element Q by a drive signal from the terminal T ₃ in this state, the charge stored in the capacitor C of the oscillating transformer TRA primary coil TRa
Release. Next, when the switching element Q is turned off, the secondary coil TRb of the oscillation transformer TRA is placed in FIG.
A high-frequency pulse PA as shown in FIG. 5A is generated and applied to the rare gas discharge lamp 1, and the rare-gas discharge lamp 1 has an oscillating pulse shape as shown in FIG. The lamp current LA flows to light the lamp. Such a lamp current LA is also generated when the rare gas discharge lamp 1 is turned on with a sine-wave high-frequency voltage. This is desirable because efficiency can be improved.

Next, another embodiment in which the form of the external electrode of the rare gas discharge lamp of the present invention is changed is shown in FIGS. 3 (B) and 3 (C).
It will be described based on.

FIG. 3B shows that each of a plurality of external electrodes 6a... Formed on the outer peripheral surface of the cylindrical envelope 2 is divided into a plurality in the longitudinal direction of the envelope 2 (in FIG. 4). For example, one external electrode 6 shown in FIG.
a is divided into four parts: a left end electrode part 6a-1, a left center electrode part 6a-2, a right center electrode part 6a-3, and a right end electrode part 6a-4. It is arranged in a straight line with a distance in the direction. Similarly, the other external electrode 6b is divided into four parts: a left end electrode part 6b-1, a left center electrode part 6b-2, a right center electrode part 6b-3, and a right end electrode part 6b-4. , Are arranged linearly at a distance from each other in the longitudinal direction of the envelope 2.

The rare gas discharge lamp 1 shown in FIG.
When used as a document reading light source of the A-device, an external electrode to which a high-frequency voltage is applied can be selected according to the width of the document to be used. That is, when the width of the document is changed from A4 to B5, for example, one external electrode 6a
Without applying a high-frequency voltage to the left end electrode portion 6a-1, the left center electrode portion 6a-2, the right center electrode portion 6a-3, and the right end electrode portion 6a
By controlling so that a high-frequency voltage is applied only to a-4, the rare gas discharge lamp 1 can be efficiently lit with a lighting length corresponding to the width of the document.

FIG. 3 (C) shows a triangular wave shaped irregular portion 9 having a periodicity on the longitudinal edges of a plurality of external electrodes 6a, 6b... Formed on the outer peripheral surface of the cylindrical envelope 2. Is formed. In the rare gas discharge lamp 1 shown in FIG. 3C, when a high frequency voltage is applied to the external electrodes 6a, 6b,... As a result, the lighting voltage can be further reduced. The shape of such a deformed portion 9 is not limited to a triangular wave, but may be a rectangular wave or an arc wave. Also, in FIG. 3 (C), the peripheral edge on one side of each of the external electrodes 6a, 6b... Is irregular, but both sides may be irregular.

[0030]

As described above, according to the present invention, the inner electrode is formed at the center of the inside of the envelope, and the plurality of external electrodes are formed on the outer peripheral surface of the envelope at a distance. When a high frequency voltage is applied to the internal electrode and the external electrode for lighting, the discharge distance between the internal electrode and the external electrode is shortened, and the envelope part interposed therebetween becomes one place. From
Even if the high-frequency voltage applied between the electrodes is reduced in voltage, the lighting can be reliably performed, and the cost of the lighting device can be reduced.

If the rod-shaped internal electrode is grounded, generation of flicker can be suppressed, and stable discharge can be expected.

If the high-frequency voltage generating circuit for lighting the rare gas discharge lamp is constituted by a pulse generating circuit, the luminous efficiency of the rare gas discharge lamp can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a rare gas discharge lamp and a block diagram of a lighting device showing an embodiment of the present invention.

FIG. 2 is a side view including a partial cross section showing an outline of the rare gas discharge lamp of FIG. 1;

3A is a perspective view of the rare gas discharge lamp of FIG. 1, and FIG. 3B is a perspective view of the rare gas discharge lamp of FIG. 1 when an arrangement pattern of external electrodes is changed. (C) is a perspective view when the external electrode shape of the rare gas discharge lamp of FIG. 1 is changed.

FIG. 4 is a circuit diagram of a pulse generation circuit as a specific example of a high-frequency voltage generation circuit in the lighting device of FIG. 1;

FIG. 5 is a waveform chart showing a relationship between a high-frequency pulse and a lamp current of the pulse generation circuit of FIG. 4;

FIG. 6 is a sectional view of a conventional rare gas discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rare gas discharge lamp 2 Enclosure 3 Light emitting layer 4 Aperture part 5 Internal electrode 6a-6e External electrode 7 High frequency voltage generation circuit H (7) Pulse generation circuit

Claims (4)

[Claims] 1. A cylindrical envelope filled with a rare gas,
A light-emitting layer formed on the inner surface of the envelope, a rod-shaped internal electrode fixedly arranged over the entire length of the envelope in the center of the interior of the envelope, and a plurality of portions on the outer peripheral surface of the envelope. A rare gas discharge lamp comprising: a plurality of external electrodes fixedly arranged to be separated from each other. 2. A cylindrical envelope enclosing a rare gas, a light-emitting layer formed on the inner surface of the envelope, and a rod-shaped member fixedly arranged over the entire length of the envelope in the center of the interior of the envelope. A rare gas discharge lamp having a plurality of external electrodes fixedly spaced apart from each other at a plurality of locations on the outer peripheral surface of the envelope, and a high-frequency voltage generating circuit for generating a high-frequency voltage; Applying a high-frequency voltage generated by the high-frequency voltage generation circuit to an internal electrode of the gas discharge lamp and a selected external electrode of the plurality of external electrodes to turn on the rare gas discharge lamp. Lighting device. 3. The rare gas discharge lamp lighting device according to claim 2, wherein an internal electrode of the rare gas discharge lamp is grounded. 4. The rare gas discharge lamp lighting device according to claim 2, wherein said high frequency voltage generating circuit is a pulse generating circuit for generating a high frequency pulse.