JPH02288147A - Low pressure discharge lamp - Google Patents

Abstract

PURPOSE:To enhance the brightness of one of the bulb ends and the starting characteristic by bending one end of the bulb, and leading the outer lead, which is connected with an electrode mounted sealdedly in this bent end, to the other end of bulb along its outer surface. CONSTITUTION:The tip of a bulb 2 is bent approx. in U-form, and a cold cathode 6 is mounted sealded at the tip this bent part 3, so that the Farady darkness generated in the neighborhood of this cold cathode 6 during glow discharge will be generated in the L zone below the bent top, with no such darkness generated in the upper straight portion functioning as the pointer. Therefore, a slit 13 for light penetration is extended till the top of the bent part 3 to enable up to the top to perform light emission. The cathode 6 mounted sealedly at the tip of the bent part 3 is connected with an outer lead 8, which leads in the axial direction along the outer surface of the bulb 2 so as to play the role of a proximity conductor having an opposite potential to the electrode on the base end side. This enhances the brightness of the bulb tip and also the starting characteristic.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a low-pressure discharge lamp such as a cold cathode discharge lamp, a xenon glow discharge lamp, etc. formed by a thin hollow bulb. .

(Prior Art) Recently, low-pressure discharge lamps have been used as direct display points on the display panels of automobile instruments and electrical equipment.

That is, a low-pressure discharge lamp, such as a xenon glow discharge tube, is made into an extremely thin hollow needle-shaped bulb with an inner diameter of about 2 mm to 3 mm, and one end of this discharge lamp is attached to the rotating pointer shaft of a meter. When the pointer shaft rotates, the discharge lamp also rotates integrally, so that the discharge lamp functions as a pointer, and when the discharge lamp is turned on, it emits light itself and illuminates the display scale. Therefore, it has the advantage of not requiring special lighting.

A discharge lamp used as a pointer for such a meter is equipped with an internal electrode inside a bulb in the shape of a long, slender hollow rod, and a band-shaped external electrode is provided along the axial direction on the outer surface of this bulb. The bulb is configured to apply high frequency power between the bulb and the external electrode to generate glow discharge within the bulb.

In addition, this discharge lamp has a light-shielding coating made of synthetic resin formed on the outer surface of the bulb, which is shaped like an elongated hollow rod. The light is emitted from this elongated strip-shaped light transmission slit. Therefore, this type of discharge lamp is an aperture-shaped lamp, and therefore, the light emitting part that serves as a pointer is shaped like an extremely thin needle.

Generally, in order to quickly and accurately read the scale displayed on the meter panel, it is desirable that the tip of the pointer be close to the scale.

When using the above discharge lamp as a meter pointer, it is desirable that the tip of the light emitting part be as close to the scale as possible, and for this purpose the discharge lamp must emit light with sufficient brightness all the way to the tip of the bulb. be done.

(Problems to be Solved by the Invention) However, [2] In the conventional pointer discharge lamp, an external electrode is arranged up to the tip of the bulb, and a discharge is generated between this external electrode and an internal electrode provided at the other end. Since it was designed to emit light by emitting light, the distance from the internal electrode was the farthest position.
There is a problem that the potential difference becomes smaller than in other parts, and the emission intensity tends to decrease, resulting in a lower amount of light at the tip.

For this reason, it is being considered to eliminate the external electrode and provide internal electrodes at both ends of the bulb.

However, if an internal electrode is placed at one end of the bulb, which is the tip of the pointer, the area closer to the tip of the bulb than this internal electrode will not emit light, and a Faraday dark area will occur in the area closer to the electrode, and this dark area will effectively emit light. Therefore, when used as a guideline for the meta, there is a problem that the brightness at the tip is insufficient.

In the present invention, the brightness at one end of the bulb is improved,
The present invention aims to provide a low-pressure discharge lamp that also improves starting performance.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, one end of the bulb is bent, an internal electrode is sealed in this bent end, and an outer lead connected to this electrode is placed along the outer surface of the bulb. The other end of the bulb is connected to a power source together with the other electrode.

(Function) According to the present invention, since one end of the bulb that seals the internal electrode is bent, this bending start part becomes the substantial tip of the bulb, and a Faraday dark part is formed from this bending part to the electrode side. can improve the brightness of the bulb tip. Moreover, since the outer lead connected to this electrode is guided to the other end of the bulb along the outer surface of the bulb, this outer lead acts as a proximal conductor, improving starting performance.

(Example) The present invention will be described below based on an example shown in FIGS. 1 to 5.

In the figure, reference numeral 1 indicates a low-pressure discharge lamp used as a pointer for automobile speedometers, etc. The discharge lamp of this embodiment is a cold cathode discharge lamp, and this discharge lamp 1 is equipped with a glass bulb 2 in the shape of an elongated hollow rod. ing.

For example, the glass bulb 2 has an outer diameter of 2.5+am and a total length of 60mm.
It has a IIIs culm and is approximately needle-shaped.

The tip of the bulb 2 is bent, for example, into a substantially U-shape, and this bent portion 3 is bent downward. Therefore, this valve 2 is formed into a substantially J-shape as a whole.

A phosphor wave film 4 is formed on the inner surface of the bulb 2.
Moreover, in this bulb 2, a discharge gas consisting of at least one of xenon and krypton is present at a rate of 5 to 90 Lor.
r, preferably about 20 torr.

Cold cathodes 5 and 6 are sealed as internal electrodes at the base end and bent end of the bulb 2, respectively, and these cold cathodes 5 and 6 are connected to lead wires that are passed through the sealed end of the bulb 2 in an airtight manner. It is connected to 7,7.

The cold cathode 6 sealed on the side end of the bent portion 3 has a lead wire 7 connected to an outer lead 8 provided along the outer surface of the bulb 2 . In this embodiment, the outer lead 8 is constructed by applying a paste such as carbon phenol or silver epoxy in the form of a band in the axial direction along the outer surface of the bulb 2, and then firing the paste.

In this case, the outer lead 8 is located inside the valve 2 in the bending direction and is provided along the axial direction.

On the outer surface of the base end of the bulb 2, a first power receiving terminal 10 made of a conductive paste such as silver epoxy is formed in the form of a film. This first power receiving terminal 10 is connected to the cold cathode 5 via the lead wire 7 mentioned above.

Further, on the outer surface of the bulb 2, the first power receiving terminal IO is provided.
A second power receiving terminal 11 is formed at a position spaced apart from each other in the axial direction. The second power receiving terminal 11 is also made of conductive paste such as silver epoxy, and is similar to the first power receiving terminal lO.
They are formed in the circumferential direction with a predetermined width spaced apart from each other in the axial direction. The second power receiving terminal 11 is formed so as to avoid the slit portion 8 of the light shielding film 7, which will be described later, and is connected to the outer lead 8.

A light shielding film 12 is formed on the outer surface of the bulb 2.

The light-shielding film 12 is made of carbon, epoxy resin, and adhesive, and is formed on the surface of the bulb 2 on which the outer lead 8 is provided, covering the outer lead 8, and on the surface on which the outer lead 8 is provided. On the opposite surface, a light transmitting rib I portion 13 extending in the axial direction and not forming the light shielding wave film 12 is formed. That is, valve 2
As shown in cross section in FIG. 5, an outer lead 8 is provided on one side of the outer surface of the outer lead 8.
A light-transmitting slit portion 13 on which the light-shielding wave film 12 is not formed is formed on the other side 180 degrees opposite to the light-transmitting slit portion 13 . Therefore, the light within the bulb 2 is emitted to the outside only through the light transmission slit section 13, and therefore the cold cathode fluorescent lamp 1 has an aperture shape.

Note that the light transmission slit portion 13 extends to the bending top of the bending portion 3 .

The light-shielding wave film 12 also includes the light-transmitting slit portion 1
3, a first power receiving terminal 10 and a second power receiving terminal 1
The first power receiving terminal lO and the second power receiving terminal 11 are exposed on the outer surface of the lamp l.

The cold cathode discharge lamp 1 configured in this way has a lamp holder 2.
Attached to 0.

The lamp holder 20 is made of an electrically insulating material and has a U-shaped cross section, and has first and second power supply terminal tongues 21 and 22 fixed thereto at a distance from each other in the longitudinal direction. These power supply terminal tongue pieces 21 and 22 are formed by bending conductive leaf springs such as phosphor bronze into a substantially U shape, and the holding pieces 23a are opposed to each other as shown by the imaginary lines in FIG.

The valve 2 is held between the valves 23b and 23b.

The lamp holder 20 is fixed to a pointer shaft 25 of the meter, and rotates integrally with the pointer shaft 25 when the pointer shaft 25 rotates.

Note that the pointer shaft 25 of this embodiment is constituted by a hollow shaft (not shown), and two covered cords (not shown) are inserted into this hollow pointer 1d125, and one end of each of these covered cords is connected to the first end. and second power supply terminal tongue piece 21.
22, and the other end is connected to a high frequency power source.

1-2 The base end of the cold cathode discharge lamp 1 is attached to a lamp holder 20. That is, the first power receiving terminal IO and the second power receiving terminal film 11 formed on the outer surface of the bulb 2 are opposed to the first power feeding terminal tongue piece 21 and the second power feeding terminal tongue piece 22 on the lamp holder 20 side. When the lamp 1 is pushed in from the opening side of the lamp holder 20, the first and second power supply terminal tongue pieces 21 and 22
Each of the clamping pieces 23a.

23b is the first power receiving terminal lO and the second power receiving terminal 11
The valve 2 is mechanically supported by sandwiching the parts.

Therefore, the cold cathode discharge lamp 1 is fixed to the lamp holder 2o. In this case, the first and second power supply terminal tongue pieces 21.
22 are the first power receiving terminal 10 and the second power receiving terminal 1, respectively.
1, so these power supply terminal tongues 21.
The inner electrode 3 and the outer electrode 6 are connected to a high frequency power source by means of a covered cord connected to 22.

The cold cathode discharge lamp 1 attached to such a lamp holder 20 is attached with the bent portion 3 formed at the tip of the bulb facing downward, and the light transmission slit portion 13 is positioned on the upper surface. It is something.

According to such a configuration, the base end side of the cold cathode discharge lamp I is supported by the lamp holder 20, and in this case, the first power supply terminal tongue pieces 21 and TX2 are located at two locations spaced apart in the axial direction.
Since it is held between the power supply terminal tongues 22, the strength of the bulb supported by the lamp is high even though the base end is supported.

Further, high frequency power is supplied to the cold cathodes 5 and 6 installed at both ends from the first power feeding terminal tongue piece 21 and the second power feeding terminal tongue piece 22 via the first power receiving terminal 10 and the second power receiving terminal 11. Therefore, a glow discharge is generated between these cold cathodes 5 and 6 in the bulb 2.

This glow discharge excites the phosphor wave film 4 to promote light emission, and this light emission is emitted to the outside from the slit portion I3.

Therefore, in addition to the fact that the bulb 2 is originally thin, the slit portion 13 exhibits an even narrower band of light, making the discharge lamp 1 suitable for indicating a display scale as a pointer. Moreover, since it shines by itself, there is no need for any other special light source.

The lamp holder 20 is fixed to a pointer shaft 25, and when the pointer shaft 25 rotates, the lamp holder 20 is also rotated, so the discharge lamp 1 attached to the lamp holder 20 is also rotated together. Since the vehicle is rotated and moved to a position according to the vehicle speed, the speed scale can be indicated.

In this embodiment, the tip of the bulb 2 is bent into a substantially U-shape, and the cold cathode 6 is sealed at the tip of this bent portion 3, so that the Faraday dark area generated near the cold cathode 6 during glow discharge is at the top of the bend. It occurs closer to the tip, that is, in the lower L region, and does not occur in the upper straight part that functions as a pointer. Therefore, the light transmitting slit section 13 can be extended to the tip of the upper straight section, that is, to the top of the bent section 3, and the light can be emitted up to this top.

In other words, in the conventional case, the region g in FIGS. 3 and 4 did not emit light or had a low luminous intensity, but by adopting the bent structure as in this embodiment, the region g in FIGS. The region g in Fig. 4 can also be emitted with sufficient brightness, so that when used as a pointer, the indication on the scale becomes clear.

The cathode B sealed at the tip of the bent portion 3 is connected to the outer lead 8, and since the outer lead 8 is guided in the axial direction along the outer surface of the bulb 2, the outer lead 8 is connected to the proximal end. It plays the role of a proximate conductor having a potential opposite to that of the electrode 5. That is, at the time of starting, electrons are attracted to promote starting, thereby making it possible to start quickly and reliably.

Since the outer lead 8 is arranged along the axial direction on the surface opposite to the light transmission slit section 13, it does not become an obstacle to light emission.

Note that the present invention is not limited to the configuration of the above embodiment.

That is, in the above embodiment, the bent portion 3 is formed in a substantially U-shape, but as shown in another embodiment in FIG. 6, the bent portion 3 may be formed in a substantially U-shape.

Furthermore, the outer lead 8 is not limited to being formed by applying a paste such as carbon phenol or silver epoxy; for example, as shown by the imaginary line in FIG. It may be guided toward the proximal end along the outer surface of the. In this case, the covering cord 30 may be fixed to the bulb 2 using adhesive, adhesive tape, or a heat-shrinkable tube.

Furthermore, in Example 2, the case where the discharge lamp of the present invention is used as a pointer of a meter has been described, but the present invention is not limited to this. Good too.

Further, the electrode is not limited to a cold cathode type, but may be a hot cathode type, and at least one of xenon, krypton, neon, argon, etc., or mercury may be sealed inside.

[Effects of the Invention] As explained below, according to the present invention, one end of the bulb that seals the internal electrode is bent, so this bending start part becomes the substantial tip of the bulb, and the electrode can be connected from this bent part. A Faraday dark area is formed near the bulb, and the brightness of the substantial tip of the bulb can be improved. Moreover, since the outer lead connected to this electrode is guided to the other end of the bulb along the outer surface of the bulb, this outer lead acts as a proximal conductor, improving starting performance.

[Brief explanation of the drawing]

1 to 5 show one embodiment of the present invention, in which FIG. 1 is an exploded perspective view of a discharge lamp and lamp holder used as a meter pointer, FIG. 2 is a plan view thereof, and FIG. The figure is an enlarged cross-sectional view of the part ■ in Figure 1, Figure 4 is a plan view of that part, Figure 5 is a cross-sectional view taken along line V-v in Figure 2, and Figure 6 is another embodiment of the present invention. FIG. 3 is a sectional view of main parts showing an example. ■... Cold cathode discharge lamp, 2... Bulb, 3... Bent part, 4... Fluorescent coating, 5.6... Cold cathode 8...
- Outer lead, 12... Light-shielding coating, 13... Light transmission slit portion, 20... Lamp holder. Applicant's Representative Patent Attorney Takehiko Suzue

Claims (1)

[Claims] In a low-pressure discharge lamp in which internal electrodes are sealed at both ends of an arc tube bulb, one end of the bulb is bent, and an outer lead connected to the electrode sealed at the bent end is attached to the outer surface of the bulb. A low-pressure discharge lamp characterized in that the lamp is led along the other end of the bulb, and the other end of the bulb is connected to a power source together with the other electrode.