JPH0589851A - Low pressure discharge lamp - Google Patents

Abstract

PURPOSE:To heighten the illuminance of an effective light emitting surface. CONSTITUTION:A pair of conductors 2, 3 apart in the circumferentially direction are installed at the outer surface of the bulb of a low pressure discharge lamp, and the relation A>B shall be held under the condition that the side face of bulb situated between the conductors 2, 3 is made working as an effective light emitting surface 6, where A is the inter-conductor distance of effective light emitting surface and B is inter-conductor distance on the opposite side 7. This enlarges the open area of the effective light emitting surface, which increases the luminous energy emitted in this direction and heightens the illuminance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low pressure discharge lamp in which a conductor such as an external electrode, an auxiliary electrode or a proximity conductor is formed on the outer surface of a bulb.

[0002]

2. Description of the Related Art For example, in a fluorescent lamp used as a light source of OA equipment, a backlight of a display device, or the like,
There is one in which discharge is maintained by a pair of external electrodes formed on the outer surface of the bulb.

That is, the lamp shown in FIG. 4 is, as shown in FIG. 4 (a), a straight tube type bulb 1 whose both ends are closed.
A pair of external electrodes 2, which are circumferentially spaced from each other on the outer surface of the
3 is provided, and these external electrodes 2 and 3 are connected to a high frequency power source 4. Each of these external electrodes 2 and 3 is formed in a strip shape along the axial direction of the valve by a conductive paint such as silver paste. As shown in FIG. 4B, a phosphor coating 5 is formed on the inner surface of the bulb 1, and a predetermined amount of mercury and a rare gas are enclosed in the bulb 1. The bulb 1 may be a rare gas discharge lamp in which only a rare gas such as xenon is enclosed.

In such a discharge lamp, when a high-frequency current is passed between the high-frequency power source 4 and the external electrodes 2 and 3, a discharge is generated in the bulb 1, and mercury or a rare gas is ionized and excited to emit ultraviolet rays. It is converted into visible light by the phosphor coating 5 and emitted to the outside.

By the way, since the external electrodes 2 and 3 are made of a conductive material, they block light. However, the width W of these external electrodes 2, 3
Is a factor that determines the cross-sectional area of the current path, and it is necessary to have a predetermined width in order to maintain stable discharge in view of the relationship between the applied voltage and the lamp current.

[0006]

However, the recent discharge lamps of this type tend to have a small tube diameter, and therefore the tube diameter is made thin while maintaining the width W of the external electrodes 2 and 3 at a predetermined width. Then, the distances C and C between the external electrodes 2 and 3 along the circumferential direction of the bulb 1 become short, that is, the external electrodes 2 and 3 approach each other along the circumferential direction of the bulb 1, and when these approach too close, these There is a problem that a creeping discharge is generated between the external electrodes 2 and 3.

When the external electrodes 2 and 3 come too close to each other along the circumferential direction of the bulb 1, the area of the light emitting portion formed between the external electrodes 2 and 3 becomes small, so that the light emitting area becomes small. ..

In this case, if the light emitting portion on one side and the light emitting portion on the other side between the external electrodes 2 and 3 have the same dimensions C, C, FIG.
As shown in the light distribution characteristic chart shown in (1), the light distribution is evenly divided into one side and the other side, and the light distribution becomes sharp. In such a case, the illuminance decreases.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a low pressure discharge lamp capable of increasing the illuminance on the effective light emitting surface side.

[0010]

SUMMARY OF THE INVENTION The present invention is a low-pressure discharge lamp having a pair of conductors circumferentially spaced from each other on the outer surface of the bulb, wherein one side surface of the bulb is located between the pair of conductors. In the case of an effective light emitting surface, if the distance between the conductors along the effective light emitting surface is A, and the distance between the conductors along the opposite surface is B, then A> B.

[0011]

According to the present invention, since the light emitting area of the effective light emitting surface is increased, the amount of light emitted in this direction is increased and the illuminance is increased.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in FIGS. In the figure, 1 is a straight tube type valve with both ends closed, and 2 and 3 are a pair of external electrodes 2 and 3 which are provided on the outer surface of the straight tube type valve 1 so as to be circumferentially separated from each other. Each of 2 and 3 is formed in a band shape along the axial direction of the valve by a conductive paint such as silver paste. And these external electrodes 2,
3 has a predetermined width W and is connected to the high frequency power supply 4. As shown in FIG. 1B, a phosphor coating 5 is formed on the inner surface of the bulb 1, and a predetermined amount of mercury and a rare gas are enclosed in the bulb 1.

In such a discharge lamp, when a high-frequency current is passed between the high-frequency power source 4 and the external electrodes 2 and 3, a discharge is generated in the bulb 1, and mercury or a rare gas is ionized and excited to emit ultraviolet rays. It is converted into visible light by the phosphor coating 5 and emitted to the outside.

The external electrodes 2 and 3 are separated by a distance A along the effective light emitting surface, that is, the surface 6 facing upward in FIG.
However, it is formed larger (A> B) than the separation dimension B along the ineffective light emitting surface, that is, the surface 7 facing downward in FIG.

However, the separation dimension B between the external electrodes 2 and 3 on the ineffective light emitting surface 7 is set to have a distance of 1 mm or more per 1 kV of applied voltage. Needless to say, the dimension A on the effective light emitting surface 6 side has an interval of 1 mm or more per 1 kV of applied voltage.

According to this structure, the distance A between the external electrodes 2 and 3 on the effective light emitting surface 6 side is larger than the distance B on the ineffective light emitting surface 7 side (A> B). Therefore, the bulb 1 has an optically large opening area on the effective light emitting surface 6 side, and the amount of light traveling in this direction is larger than in the opposite direction. Therefore, as in the light distribution characteristic diagram shown in FIG. 2, the light distribution on the effective light emitting surface side increases, and the illuminance in this direction increases.

In this type of lamp, a reflecting mirror may be provided behind the ineffective light emitting surface 7 to direct all the light emitted from the lamp toward the effective light emitting surface 6 side. The more light there is, the better the efficiency.

In such a structure, the distance B between the external electrodes 2 and 3 on the side of the ineffective light emitting surface 7 becomes small, but creeping discharge can be prevented if the distance is 1 mm or more per 1 kV of applied voltage.

In the case of the aperture type discharge lamp, as shown in FIG. 3, by forming the phosphor coating 10 or the reflection coating on the inner surface of the bulb 1 leaving a predetermined opening angle θ,
It is known that light is emitted from the optical opening 11.

In the case of such an aperture type discharge lamp,
A pair of external electrodes 2 along the opening edge of the optical opening 11,
If 3 is provided, there is no problem that the opening 11 is shielded by the external electrodes 2 and 3. However, also in this case, it is necessary that the distance between the external electrodes 2 and 3 be 1 mm or more per 1 kV of applied voltage on both the opening 11 side and the opposite side.

In the above embodiment, the case where a pair of conductive bands provided outside the bulb 1 is used as the external electrodes 2 and 3 has been described, but the present invention is not limited to this, and the main discharge is generated inside the bulb. It is also possible to use the internal electrodes provided, and the pair of conductive bands provided outside the valve 1 may be used as electrodes for assisting starting, or may be used as adjacent conductors. The internal electrodes may be cold cathodes or hot cathodes. The present invention is not limited to the fluorescent lamp in which the bulb 1 is filled with mercury and a rare gas for starting, but may be a rare gas discharge lamp in which a rare gas such as xenon is filled.

[0022]

As described above, according to the present invention, the distance between conductors along the effective light emitting surface is A, the distance between conductors along the opposite surface is B, and A> B. Since the open area of the light emitting surface is increased, the amount of light emitted in this direction is increased and the illuminance is increased.

[Brief description of drawings]

1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a perspective view of a low-pressure discharge lamp, and FIG. 1B is a sectional view taken along line XX in FIG.

FIG. 2 is a diagram showing a light distribution distribution characteristic of the same embodiment.

FIG. 3 is a sectional view of an aperture type discharge lamp showing a second embodiment of the present invention.

FIG. 4 shows a conventional structure, in which (a) is a perspective view of a low-pressure discharge lamp, and (b) is a sectional view taken along line XI-XI in (a).

FIG. 5 is a diagram showing a light distribution distribution characteristic of the same example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Glass bulb, 2 ... External electrode, 5 ... Fluorescent film, 6 ... Effective light emitting surface, 7 ... Ineffective light emitting surface.

Claims (3)

[Claims] 1. A low-pressure discharge lamp in which a pair of conductors are provided on the outer surface of the bulb so as to be separated from each other in the circumferential direction, and when one side surface of the bulb located between the pair of conductors is an effective light emitting surface, When the distance between the conductors along the effective light emitting surface is A and the distance between the conductors along the opposite surface is B, A> B. 2. The distance B between the pair of conductors on the opposite surface is 1 with respect to the voltage applied to the conductors.
The low-pressure discharge lamp according to claim 1, wherein the low-pressure discharge lamp has a distance of mm / 1 kV or more. 3. If the lamp has an aperture shape,
The low pressure discharge lamp according to claim 1 or 2, wherein a pair of conductors are provided along the opening edge of the aperture portion.