JPH04249059A - Fluorescent lamp with three lead system and ground electrode guard - Google Patents

Abstract

PURPOSE: To electrically connect an electrode lead with an electrode guard inexpensively during assembly of a lamp. CONSTITUTION: A metal conductive link 28 between a metal electrode guard 26 of fluorescent lamp and one of lamp pins 40, 42, an electrode 20, and metal electrode guard 26 are really keep at a same voltage to decrease power consumption. The conductive link is a lead line connected from a metal electrode guard 26 to one lamp pin.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to a fluorescent lamp having a metal electrode guard connected to one of the lamp electrodes, and more particularly to a fluorescent lamp which can be manufactured quickly and economically with slight modifications to existing machinery. This type of lamp makes it possible.

0002

BACKGROUND OF THE INVENTION Low pressure mercury vapor discharge lamps with a fluorescent layer for light emission, commonly known as fluorescent lamps, have electrodes generally made of coils of tungsten wire. This electrode is coated with a material that promotes the thermal release of electrons. During operation of the lamp, tungsten and emissive material evaporate or sputter from the electrodes and deposit in the form of tungsten and tungsten products on the lamp wall in the area of the electrodes. This adhesion causes visible blackening.
ening) and has a detrimental effect on lamp operation.

One technique for suppressing blackening from the electrode material is to partially surround the electrode with a guard. This guard is typically in the form of a closed ring made of conductive metal strips and is placed around the sides of the electrode. When the electrode is serving as an anode, it is desirable to use a guard as part of the electrode. This increases the effective area of the anode and thus reduces the anode drop.

No. 4,891,551, a guard is connected to one of the electrode leads via a conductive link at a point between the recessed stem and the guard, thus allowing the guard to connect to the electrode without regard to polarity. A lamp is disclosed having a grounded and fused electrode guard maintained at the same potential. This U.S. patent
Connecting the electrode guard to one of the electrode leads represents an improvement over the prior art because it increases the effective area of the anode, reduces anode drop, and improves lamp efficiency.

However, the aforementioned US patent presents problems in automating the welding of conductive links because the welded joints are located in different geometric planes relative to the electrode and electrode assembly. Moreover, the disclosed spot welding is difficult because the dimensions of the components involved are very small and fragile.
Requires quick and skilled work.

US Patent Application No. 7-456,027 (December 22, 1989), which is a continuation-in-part of US Patent Application No. 7-200382, filed March 31, 1988.
US Pat. No. 5,001,300 discloses an improvement to the spot welding disclosed in the above-mentioned U.S. patent. This US patent application shows the use of a bimetallic strip that connects one of the leads to the guard support at a location between the recessed stem and the guard during operation of the lamp. Upon starting, the heat from the discharge bends the bimetal to connect the lead and the electrode guard, thus maintaining the guard and electrode at the same potential regardless of polarity during operation of the lamp. This bimetallic strip requires only one point welding compared to the line link of the aforementioned US patent which requires two welds. However, the bimetallic strip must be fed, cut and positioned before welding, which requires mechanization after the stem assembly consisting of the recessed stem, electrode lead and guard support has already been formed. Requires.

[0007]

SUMMARY OF THE INVENTION It is an object of the invention to make the connection between the electrode lead and the electrode guard easy to make during lamp assembly in an inexpensive manner, independent of the polarity of the electrode voltage. The object of the present invention is to obtain a fluorescent lamp having an electrode guard which is kept at the same potential as the electrodes.

Another object of the invention is to provide a fluorescent lamp in which the electrical connections described above can be substantially completed during formation of the stem assembly.

A further object of the invention is to reduce the number of parts that must be assembled in such a lamp.

0010

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a lamp vessel, an electrode disposed within the lamp vessel, and an electric current passing through the lamp vessel for applying a voltage to the electrode. an extending conductive element, a metallic electrode guard partially surrounding said electrode, and a conductive link maintaining said electrode guard at substantially the same potential as said electrode regardless of the polarity of the electrode voltage. In the fluorescent lamp, the conductive link is adapted to be connected to the electrode guard, extend through the lamp vessel and connect to the conductive element outside the lamp vessel. be.

In one embodiment of the invention, the conductive link is a conductive lead extending hermetically through the lamp vessel and connected to the rectifying element.
nts) There is no.

In another embodiment of the invention, the conductive link supports an electrode guard within the lamp vessel;
Reduces the number of parts in the stem assembly by eliminating the need for a separate electrode guard support.

In a further embodiment of the invention, said conductive link melts in response to an overcurrent through said conductive link during lamp operation to isolate the electrode guard from one of the conductive elements. Has a fused portion outside the effective lamp vessel.

In yet another embodiment of the invention, the lamp electrode is a filament electrode having respective ends connected to the first and second leads, respectively, and a voltage is applied across the electrode to cause a current to flow through the electrode. to flow. The lamp has first and second leads connected to respective ends of the electrode, and a third lead welded to and supporting the electrode guard support. This configuration has the advantage that the third lead, which maintains the electrode guard at the same potential as the electrode, can be sealed into the recessed stem along with the other two leads using conventional tooling and glass forming techniques. . The third lead is
a fusible portion on the exterior of the lamp vessel; a copper-coated iron-nickel alloy (Dumet) portion extending through the stem; and a length of wire sufficient to support the electrode guard extending from the stem. Preferably, it is a 3-part reed that provides a 3-part reed. These parts are usually butt welded together.

In yet another embodiment of the invention, the third lead is connected to the lamp cap contact with a conductive element or lead providing voltage to the electrode. This contact point is
Preferably, it is a tubular pin having a hole therein, and the third lead is twisted together with the first lead or the second lead, inserted into the hole of the pin, and fixed thereto by clamping, soldering or welding. This connection is preferred because it can be easily made through normal automation.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows, in cross section, the end of a fluorescent lamp with a lamp electrode assembly. The lamp has a lamp vessel 10 of tubular cross-section with a small diameter end 12 closed by a recessed stem 14. The inner surface of this lamp vessel is coated with a fluorescent material 16 that fluoresces under ultraviolet light. The electrodes 20 within the lamp vessel 10 are energized to maintain a discharge through the plasma of mercury atoms within the lamp. The atoms are excited and emit ultraviolet light, which is incident on the coating of fluorescent material 16. The fluorescent material 16 emits light in the visible range and emits light. This condition of the lamp is normal.

[0017] Stem assembly 18 includes first and second
Filament electrode 2 supported by leads 22 and 24
0 and a third lead 28 that supports a short cylindrical guard or shield 26. This electrode guard 26 has a diameter of approximately 20 mm, a height of 6 mm, and partially surrounds the electrode 20. The leads 22, 24 and 28 extend airtightly through the stem.

The lamp end cap 44 is attached to the lamp vessel 10.
and supports two pins 40, 42 which are insulated from each other in the conventional manner. The pin for this contact is tubular and has a hole in it. Leads 22 and 24 are connected to pins 40 and 42, respectively.

The lead 28 has three parts joined by butt welding.
It consists of two line sections. Dumet wire section 28b is a copper-clad iron-nickel alloy that closely approximates the thermal expansion characteristics of the glass of the stem to ensure a hermetic seal. The spud line portion 28c, or support of the electrode guard 26, can be comprised of any conductive material that can be spot welded to the guard and has the requisite strength to serve as an electrode guard support. Typically,
The spud wire is a nickel-plated iron wire with a diameter of 0.6 mm. Fusible link portion 28 of lead 28
a is typically 0.0038 inch stainless steel, but can be any material and size suitable for the particular current limiting requirements of the lamp. Said soluble portion 2
8a is connected to pin 42 together with lead 24. In the lamp of FIG. 1, the fusible portion is twisted together with the outer ends of the leads 24 and inserted into the holes 42a of the pins 42 and secured therein by clamping. Alternatively, the lead 24 and the fusible portion 28a can be secured by soldering or welding.

In operation, the voltage applied to pins 40, 42 heats filament electrode 20 to promote thermal emission of electrons. A potential difference between the other electrode (not shown) at the opposite end of the lamp maintains a discharge between the two electrodes. The conductive connection between electrode guard 26 and filament electrode 20 by lead 28 increases the effective area of the electrode when it acts as a positively biased anode. This reduces anode drop and therefore less power required for lamp operation.

[0021] The stem assembly having the third lead is
The third lead is sealed together with the normal first and second leads during stem formation and replaces the electrode guard support previously embedded within the stem, thereby simplifying lamp construction. Additionally, one skilled in the art would be able to separate the outer ends of leads 22 and 24 from third lead 28, electrically connect leads 24 and 28 by twisting, and then insert the twisted leads into pin 42 and clamp them. You will find that automated manufacturing techniques can be widely used to do this. The use of metal conductive links as described above allows for a faster, more reliable, and also less expensive means of conductively coupling an electrode to an electrode guard with minor modifications to existing manufacturing equipment. This brings about an improvement.

Although the present invention has been described above with reference to preferred embodiments, it will be obvious to those skilled in the art that various modifications can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of the electrode assembly portion of the lamp of the present invention.

FIG. 2 is a plan view of an embodiment of a third lead.

[Explanation of symbols]

12 Small diameter end 14 Recessed stem 18 Stem assembly 20 Electrode 22 1st lead 24 2nd lead 26 Electrode guard 28 3rd lead 40, 42 pin

Claims (16)

[Claims] 1. A lamp vessel, an electrode disposed within the lamp vessel, a conductive element extending through the lamp vessel for applying a voltage to the electrode, and a metal partially surrounding the electrode. and a conductive link that maintains the electrode guard at substantially the same potential as the electrode irrespective of the polarity of the electrode voltage, the conductive link being connected to the electrode guard. a fluorescent lamp, extending through said lamp vessel and connected to said conductive element outside said lamp vessel. 2. The fluorescent lamp of claim 1, wherein said conductive link supports an electrode guard within the lamp envelope. 3. The conductive link includes a molten portion outside the lamp vessel that is effective to melt and disconnect the electrode guard from one of the conductive elements in response to an overcurrent passing through the conductive link during operation of the lamp. 3. A fluorescent lamp according to claim 2. 4. The fluorescent lamp of claim 3, wherein the lamp further comprises a lamp cap having contacts, and one of the conductive elements and the conductive link are connected together to said contacts. 5. The fluorescent lamp of claim 1, wherein the lamp further comprises a lamp cap having contacts, one of the conductive elements and the conductive link being connected together to said contacts. 6. A lamp vessel, an electrode disposed within the lamp vessel, extending through the lamp vessel and connected to both ends of the electrode, the electrode being energized to thereby cause the electrode to be energized. A conductive path without a rectifying element is formed between first and second leads through which a current flows, a metal electrode guard partially surrounding the electrode, and the electrode guard and one of the conductive elements. a fluorescent lamp having a metallic conductive link for maintaining the electrode guard at substantially the same potential as the electrode irrespective of the polarity of the electrode voltage, said conductive link being connected to the electrode guard and extending through the lamp vessel. What is claimed is: 1. A fluorescent lamp, characterized in that the lamp is connected to one of the leads outside the lamp vessel. 7. The fluorescent lamp of claim 6, wherein said conductive link supports an electrode guard within the lamp envelope. 8. The electrically conductive link has a molten portion external to the lamp vessel that is effective to melt and isolate the electrode guard from one of the electrically conductive elements in response to an excessive current passing through the electrically conductive link during lamp operation. A fluorescent lamp according to claim 7. 9. The fluorescent lamp of claim 8, wherein the lamp further comprises a lamp cap having contacts, one of the conductive elements and the conductive link being connected together to said contacts. 10. The contact of the lamp cap is a tubular pin having a hole therein, the conductive link and one conductive element are twisted together outside the lamp vessel, and inserted into the hole, 10. The fluorescent lamp of claim 9, wherein the fluorescent lamp is fixed to a pin. 11. The conductive link includes a first portion extending from the electrode guard and embedded within the lamp vessel to support the electrode guard; and a conductive link extending from the first portion through the lamp vessel. and a second portion having a coefficient of thermal expansion substantially equal to that of the lamp vessel to maintain an airtight seal with the lamp vessel; and a second portion extending outwardly from the second portion and passing through a conductive link during operation of the lamp. 7. The fluorescent lamp of claim 6, further comprising a third melting portion effective to melt and disconnect the electrode guard from one of the conductive elements in response to. 12. A lamp cap having a tubular lamp vessel, a recessed stem assembly hermetically sealing the lamp vessel, and a pair of contacts disposed adjacent the stem assembly; In a fluorescent lamp having an electrode disposed within a container and a metal electrode guard partially surrounding the electrode, the stem assembly has three leads passing through the stem assembly in a gas-tight manner. A first lead and a second lead of the reeds are connected to a respective lamp cap contact and an end of said electrode for supporting said electrode and applying a potential to said electrode, thereby causing a heating current to flow through said electrode. A third lead supports the electrode guard and is connected to the first and second leads.
A fluorescent lamp characterized in that one of the leads is connected externally to the stem assembly. 13. The third lead has a melting point effective to melt and disconnect the electrode guard from one of the first and second leads in response to an overcurrent passing through the third lead during operation of the lamp. Claim 12 comprising a portion outside the lamp vessel.
Fluorescent lamp. 14. The third lead and the first and second leads.
14. The fluorescent lamp of claim 13, wherein one of the leads are connected together to a lamp cap contact. 15. The lamp cap contact is a tubular pin having a hole therein, the third lead and one of the first and second leads being twisted together on the outside of the stem and inserted into the hole. 15. The fluorescent lamp of claim 14, wherein the fluorescent lamp is fixed to said pin. 16. The third lead includes a first portion extending from the electrode guard and embedded in the recessed stem to support the electrode guard, and a stem extending from the first portion. a second portion extending through and having a coefficient of thermal expansion substantially equal to the lamp vessel to maintain a gas-tight seal with the lamp vessel; 16. The fluorescent lamp of claim 15 further comprising a third fused portion effective to disconnect the electrode guard from the pin in response to excessive current through the three leads.