JPS6122552A - Electrode disposition in metal halide lamp - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to metal halide discharge lamps, and more particularly to electrode positioning for efficiency improvement in low current metal halide discharge lamps.

BACKGROUND OF THE INVENTION Metal halide discharge lamps in today's market are generally of the medium and high wattage variety. More specifically, readily available known metalnolide discharge lamps have ratings ranging from about 175 to 1500 watts.

It is also known that these metal 71 ride discharge lamps with higher wattage have higher effectiveness. Furthermore, effectiveness is directly related to efficiency, which is conveniently defined as the total lumen output relative to the input power, lumens per watt (lumens/
Watt).

The smallest known metalnolide discharge lamp used for general lighting is a 175 watt lamp. Experiments have shown that such a relatively small lamp has a capacity of about 8
Effectiveness of 0 lumens per watt (LPW) and approximately 14. O
With lumen output of OO lumens and transparent lamp approx.
At 400°, phosphor coated lamps appear to have a color temperature of about 4000°.

However, the conventional wisdom has been that metal noride discharge lamps smaller than about 175 watts are impractical due to their undesirably relatively low effectiveness. It was also expected that the color temperature of about 4400' common in today's lamps would appear in low wattage metal halide discharge lamps as well. Furthermore, a normal incandescent lamp is approximately 2
Having a color temperature of 780@, a color temperature of approximately 4400'' is considered insufficient for general lighting purposes.

OBJECTS OF THE INVENTION An object of the present invention is to provide a metal halide discharge lamp that overcomes the problems of the prior art described above. Another object of the invention is to provide an improved metal halide discharge lamp. Yet another object of the invention is to provide an improved low wattage metal halide discharge lamp with improved effectiveness. Yet another object of the invention is to provide an improved low wattage metal halide discharge lamp having an improved electrode configuration.

SUMMARY OF THE INVENTION These and other objects, advantages and possibilities of the present invention, in one aspect, include an evacuated envelope and a domed quartz dome positioned within the envelope. an arc tube having a sleeve and disposed within the domed quartz sleeve having a pair of spaced apart electrodes sealed within the arc tube, a coil attached to each electrode; is a figure of goodness ( A low wattage metal halide discharge lamp characterized by having a figure op merit) (FM).

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a low wattage metal halide arc discharge lamp 5 is hermetically sealed in a glass stem member 9 and has an evacuated envelope 7 to which an external base member 11 is secured.
It is equipped with A pair of electrical conductors 13 and 15 are enclosed in and extending through the stem member 9, allowing the discharge lamp 5 to be energized by an external power source (not shown).

In the vacuum of the evacuated envelope 7, a support member 7 is fixed to one of the electrical conductors 13, with a t-hill y to the longitudinal axis of the lamp 5.
A circular portion 19 is formed near the top of the envelope 7 by extending in parallel. This circular portion 19 works in conjunction with the top of the envelope 7 to maintain the support member 17 in proper alignment and to resist deformation due to external impacts.

A first strip 21 is welded to the support member 17 and extends therefrom in a direction perpendicular to the longitudinal axis of the support member 17. The heat storage means, such as the domed quartz sleeve 23, has a pair of opposed notches 25 and 27 at the end 28 opposite the domed portion. These notches 25
, 27 are formed so that the first strip member 21, which serves to support the dome-shaped quartz sleeve 26, slides thereon. Further, a circular band 29 surrounds the dome-shaped quartz sleeve 23 near the dome-shaped portion and is attached to the support member 17.

An arc tube 31 is disposed within the dome-shaped quartz sleeve 23. This arc tube 31 has pressure sealing parts, that is, pressure sealing parts 33 and 35 at both ends thereof. Metallic foil members 37 and 39 are enclosed within the pressure seal 33.55, and electrical conductors 41 and 43 are secured to the foil members 37.39 and extend outwardly from the pressure seal 33.35. There is. A flexible support member 45 is secured to one of the electrical conductors 41 and support member 17 . Further, a lead wire 47 is fixed to the other electrical conductor 43 passing through the dome-shaped portion of the dome-shaped quartz sleeve 23.

Additionally, a flexible spring-like member 49 connects lead wire 47 to the other of the pair of electrical conductors 13 and 15.

A pair of getters 51 and 53 connect electrical conductors 13 and 15
and acts to provide and maintain a vacuum within the evacuated envelope 7 and domed quartz sleeve 26. Further, a pair of electrodes 55 and 57 are connected to the arc tube 31.
protruding into both ends.

To explain the arc tube 31 in more detail, the pressure sealing part 3
Each of the ends of the tube immediately adjacent and containing 3 and 35 are coated with white zirconium oxide paint to make the wall temperature more uniform. Also,
The arc tube 51 contains starting gases, mercury and scandium and sodium metal halides. moreover,
Other metal halides are also suitable for the present structure.

Referring to FIG. 2, which shows an enlarged cross-section, electrodes 55.57 and pressure seals 33.35 are shown in detail. Since the ends of this structure are similar, only one end will be illustrated and described. As shown, the electrode 55 is fixed to the foil member 37, and the electrode 55 has a coil 5.
9 is installed. The coil 59 is also positioned on the electrode 55 to provide a certain distance from the pressure seal 63 to the rear of the coil 59, this certain distance is called the backspace (BS'). The electrode 55 also projects a predetermined distance into the arc tube 31, and the distance from this pressure seal 33 to the inner end of the electrode 55 is known as the insertion length (IL).

The important things are backspace (BS) and insert length (IL).
) are critical parameters and their product provides a design criterion called goodness index (FM). That is, the goodness index (FM
) is substantially equal to the product of backspace (BS) and insert length (IL). The figure of merit (FM) therefore makes it possible to obtain specific design parameters with which an optimal discharge lamp can be obtained.

Regarding the goodness factor (FM) mentioned above, for lamps with goodness factor (FM) greater than about tO and less than about t5, backspace (BS) i.e. from the back of the coil above the electrode to the pressure seal. The distance reached is approximately 0.500
．． It has been found that a range of 2 ml is preferred. Also, about Q, (14S 2cIrL (about α0
17 inches), and the distance between the electrodes is approximately t.
Lamps using thorium tungsten electrodes that are 4 cWL are preferred for low wattage lamp configurations.

Referring in detail to the graph in Figure 3, for a 100 watt metal halide discharge lamp,
) with both lamp effectiveness and color temperature. For ease of understanding, approximately 1.0
A 100 watt metal halide discharge lamp with a goodness factor (FM) greater than and less than about 15 is about 9
Effectiveness (LPW) ranging from 8 inches to 93 inches and approximately 2800
It can be seen that lamps are provided having color temperatures (Tc) ranging from about 5200° to about 5200'. It can therefore be seen that a 100 watt metal halide discharge lamp can be designed to have a very satisfactory color temperature for general lighting. Additionally, this design can provide much improved effectiveness over any conventional low wattage structure.

Although presently preferred embodiments of the invention have been illustrated and described, it will be obvious to those skilled in the art that various modifications and changes can be made without departing from the invention as defined in the claims. Aro 5゜

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a low wattage metal halide discharge lamp of the present invention, FIG. 2 is an enlarged cross-sectional view showing one electrode in the arc tube of FIG. 1, and FIG. 3 is a cross-sectional view of a given figure object of the present invention. FIG. 2 is a comparative chart showing effectiveness and color temperature for a given goodness index of low wattage metal halide discharge lamps with advantages; 5: Low wattage metal halide arc discharge lamp 7; Envelope 9; Glass stem member 15.15; Electrical conductor 17: Support member 19: Circular portion 21: Strip member 23: Domed quartz sleeve 25.27: Notch 31 : Arc tube 33.35 : Pressure sealing part 37.39 : Metal foil member 41.46 : Electric conductor 45 : Flexible support member 47 : Lead wire 51.53 Nigeta 55.57 : City 1 pole 59 : Coil

Claims (14)

[Claims] (1) The arc tube includes an evacuated envelope, a dome-shaped quartz sleeve disposed within the envelope, and an arc tube disposed within the dome-shaped quartz sleeve. and a pair of spaced apart electrodes enclosed through a pressure seal of the arc tube, each of the electrodes being spaced apart from the pressure seal and from an end of the electrode within the arc tube. and each of said electrodes has a backspace (BS) and an insertion length (I
L), where BS = distance from the pressure seal to the coil; IL = distance from the pressure seal to the end of the electrode; Low wattage metal halide discharge lamp. 2. The low wattage metal halide discharge lamp of claim 1, wherein the operating voltage of the lamp is approximately 100 volts. (3) said goodness factor (FM) is greater than about 1.0 and less than about 1.5, and said lamp has a color temperature ranging from about 2800 to about 3200 degrees Fahrenheit. Low wattage metal halide discharge lamps as described. (4) the goodness factor (FM) is greater than about 1.0 and less than about 1.5, and the lamp is about 93 to about 98;
A low wattage metal halide discharge lamp as claimed in claim 1 having an efficacy in the range of lumens/watt. 5. The low wattage metal halide discharge lamp of claim 1, wherein the arc tube filling comprises a starting gas, a metal halide of mercury, scandium and sodium. (6) The electrodes are thoriated tungsten rods having a diameter of about 0.017 inches, spaced apart from each other by about 1.4 cm, and the lamp operating voltage is about 100 volts. A low wattage metal halide discharge lamp according to item 1. (7) The backspace (BS) is approximately 0.5±0.2
A low wattage metal halide discharge lamp according to claim 1 in the range of mm. 8. The low wattage metal halide discharge lamp of claim 1, wherein said goodness factor (FM) is greater than about 1.0 and less than about 1.5, and said operating voltage is about 100 volts. (9) A low wattage metal halide discharge lamp having an evacuated envelope, a domed quartz sleeve disposed within the envelope, and an arc tube disposed within the domed quartz sleeve, comprising: The arc tube contains a gas fill therein and includes a pair of spaced apart electrodes encapsulated through a pressure seal, each of the electrodes extending from the pressure seal and from the electrode within the arc tube. having a coil spaced apart from the end of the electrode, each electrode having a distance from the pressure seal to the product of the backspace (BS) and the insertion length (IL), where BS = distance from the pressure seal to the coil; IL = the distance from the pressure seal to the coil; A low wattage metal halide discharge lamp characterized in that it has a goodness factor (FM) substantially equal to the distance to the electrode end. (10) the goodness index is greater than about 1.0 and about 1;
．． 9. A low wattage metal halide discharge lamp according to claim 9. (11) The backspace (BS) is about 0.5±0.
A low wattage metal halide discharge lamp according to claim 9 in the range of 2 mm. 12. The low wattage metal halide discharge lamp of claim 9, wherein said arc tube contains a starting gas, mercury, scandium and sodium halide. (13) the discharge lamp operates at about 100 volts, the arc tube has a goodness factor (FM) greater than about 1.0 and less than about 1.5, and the electrodes have a FM of about 0.0432.
10. The low wattage metal halide discharge lamp of claim 9, wherein the lamp is thoriated tungsten having a diameter of about 0.017 inches (cm), and wherein the electrodes are spaced about 1.4 cm apart from each other. (14) The electrode has a goodness index greater than about 1.0 and less than about 1.5, and the lamp has a color temperature ranging from about 2800 to about 3200 degrees Fahrenheit. A low wattage metal halide discharge lamp according to scope 9.