JPS58106752A - High voltage sodium 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 The present invention is a high-pressure sodium lamp comprising a sealed discharge (arc) tube made of a ceramic material, preferably polycrystalline alumina, in which sodium vapor in an amalgam with mercury and an inert Starting gas (typically 2 at cold fill pressure)
0 torr of xenon. ) in which a discharge occurs between the electrodes at both ends of the lamp. Specifically, the present invention provides: for improving lamp efficiency;
Concerning the optimization of arc tube diameter and arc length with respect to the sodium mole fraction of the sodium amalgam portion of the filling.

High-pressure sodium lamps (Lamps and lighting)
p and L 1ohtir+a ) J Henderson & Marsden (Henderson &
(Ed.), Arnold Publishing, 2nd edition, pp. 242-249. ) is now quite established. The subject of many studies has helped to understand its physical properties, resulting in significant improvements in luminous efficiency and the development of technology into lamps with lower power consumption. The results of such research are disclosed in U.S. Pat. No. 3,906,277, in which certain criteria are provided which are said to lead to a lamp with increased efficiency compared to the prior art.

Nevertheless, it is believed that it is possible to improve the efficiency of low-power, high-pressure sodium lamps by appropriate selection of arc tube diameter (inner diameter) and j'-k length (between electrode ends). ing. It is an object of the present invention to present a method for determining these dimensions for the purpose of improving lamp design, and to present an improved low power lamp designed in such a manner. In particular, the object of the present invention is to provide lamps whose power and voltage ranges do not specifically fall within the teachings of said US patent without extrapolation, such as 50 watts, 70 watts, etc.
- Contains a 130 volt lamp.

In accordance with certain features of the invention, a power rating of 50 watts and a
A high pressure sodium lamp for operation with lamp voltage drops in the range of 0 to 130 volts is presented, the lamp comprising a substantially cylindrical light emitting arc tube with an internal diameter in the range of 3.0 to 5.0 mm. containing a thermionic electrode sealed at both ends, an inert starting gas, and a 0.63 to 0
．． sodium amalgam with a sodium mole fraction in the range of 80. The arc length ((+Ua) between the electrodes is substantially defined by the following formula.

L= 3,9d +11,76x+ 0.20 V-1
5,2 where d is the internal diameter of the arc tube in m-, X is the mole fraction of sodium, and ■ is the lamp voltage drop in volts.

In accordance with another feature of the invention, a power rating of 50 watts and a
A high pressure sodium lamp for operation at lamp voltages of 0 to 90 volts is presented, the lamp having an internal diameter of 3.0 volts.
comprising a substantially cylindrical light-emitting arc tube in the range of 0.63 to 0.80 m, with a thermionic electrode sealed at both ends thereof, and an inert starting gas in the range of 0.63 to 0.80 m. sodium amalgam with a sodium mole fraction. The arc length between the electrode ends is determined substantially by the intersection of the line for selected arc tube diameter with the line for selected lamp voltage and sodium mole fraction in Figure 3 of the accompanying drawings, or by interpolation in that figure. determined.

The wall load of the arc tube diameter is preferably 20W/CI2
It is suppressed below.

The cool spot temperature of the lamp is preferably optimized by regulating heat losses therefrom.

The expression 50 watt lamp means a nominal 50 watt rated lamp designed to work at 50 watts at a particular voltage, but for various reasons such lamps may be
It is also possible to operate at different voltages with lamp power other than 0 watts.

BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly understand the present invention and achieve its effects, one embodiment of the present invention will be described below with reference to the accompanying drawings.

The early high pressure sodium lamps in common use were 400 watt lamps. The subsequent development is
While aiming to increase the luminous efficiency of these lamps, it was also aimed to provide efficient high pressure sodium lamps with low power ratings, such as the 50 watt lamp proposed by the present invention. In this development orientation, attention has been paid to satisfying three basic conditions: long life, high efficiency and good color.

It is known that the efficiency of a high pressure sodium lamp, along with its color and lifespan, depends on eleven variables. However, B, L, Denby (P.

1, Qenbigh) “Lighting Research and Engineering (
Liohtino Research and
Technolooy) J (Volume 10, No. 1, 1
978, pp. 28-32),
Some of these are specific to economic and other considerations; others may be fixed within at least known ranges during the design process.

The paper by Denby describes an experimental design approach, and many of its considerations remain useful. However, this paper did not consider the effect of amalgam ratio on lamp design, which is known to directly and indirectly affect lamp efficiency.

Therefore, the present invention provides a 50 watt high pressure sodium lamp having a lamp voltage of 70 to 130 volts, which is known to be a preferred range, and which can be specified within a range known to provide improved efficiency. Adopt the conditions,
We also present a lamp with other conditions adjusted to further improve its efficiency.

This voltage range is configured to give maximum efficiency (i.e.
For a 50 watt lamp at optimum cool spot temperature, it has been discovered that efficiency increases as tube diameter decreases, as shown in FIG. FIG. 1 is a plot of efficiency (lumens/watt) versus arc tube diameter (ms) for a 50 watt, 80 volt lamp. This figure is plotted for a sodium mole fraction of 0.686 and for the optimum temperature for maximum efficiency at the cool spot where excess amalgam collects.

The optimum cool spot temperature is obtained by using well-known methods of adjusting the focusing loss within the arc tube for operation at a particular voltage, including thermal screens, appropriate construction, and electrode length adjustment.

As shown in Figure 2, the sodium mole fraction ranges from 1 to 0.
．． It is also known that a reduction to 63 increases efficiency. Figure 2 shows a 50 watt, 80 volt high-pressure sodium ion beam with a four-way arc tube diameter at the optimum cool spot temperature.
FIG. 2 is a diagram of sodium mole fraction versus efficiency for lamps. It should be noted that as the sodium mole fraction approaches 0.6, the color becomes extremely pink and is considered unsuitable for lighting purposes.

With the above in mind, Figure 3 shows the lamp required in accordance with the present invention to achieve maximum efficiency for a lamp adjusted to its optimum cool spot temperature using the prior art. . FIG. 3 shows arc length (II) plotted as a function of arc tube diameter (Qlm) for 50 watt high pressure sodium lamps operated at 70 volts, 80 volts and 90 volts. This is combined with three sodium mole fractions, 0.63, 0.70 and 0.80, which define the range that is considered satisfactory, especially from a color point of view.
Illustrated for each. For reference, the -chamber wall load line is also shown.

From FIG. 1 it can be seen that for higher efficiency the tube diameter must be as small as possible. At the same time, the wall load limit, which is usually set below 20 W/cm2 for long-life lamps, and the arc tube size limit determine the smallest achievable tube diameter. The tube diameter located in the lower left corner of Figure 1 is the actual manufacturing limit (dos
e) Evaporation and arc tube cleanliness are fundamental issues.

)It is in.

For lamps with a sodium mole fraction between 0.63 and 0.80 and a voltage between 70 and 90 volts, the required quantities can be found by interpolation from Figure 3, and these For lamps that fall outside the range, the required amount can be determined by extrapolation.

The use of the graph is illustrated using a preferred 50 watt, 80 volt high pressure sodium lamp as an example.

Taking a satisfactory mid-range sodium mole fraction of 0.686, this lamp has an arc length of 24.51
1, it can be seen that the arc tube diameter should be 4.0 mm. The resulting wall load is 15.2 W/c+a2. The position of this lamp in FIG. 3 is indicated by an asterisk, and is similarly indicated in FIGS. 1 and 2.

The information shown by the graph of FIG. 3 can be expressed in the form of an equation that can be used to provide a lamp containing the area defined by FIG. 3 within the area to which the invention is applied. Can be done.

That is, the arc tube is equipped with sodium amalgam added with a sodium molar fraction x between 0.63 and 0.8, and the arc tube diameter (inner diameter) d is between 3.0 and 5.011.
50 watt high pressure sodium chloride with voltage drop V between 70 volts and 130 volts with optimum cool spot temperature by appropriate adjustment of focal loss.
A discharge can be produced for the lamp to operate at maximum efficiency by selecting an arc length ρ (am) defined by the following equation:

i = 3.9d +11.76x+ 0.20 V-
15,2 This formula can be applied in the following example.

Example 1 For a high pressure sodium lamp of 80 volts and 50 watts, Q = 3.9d + 11.76x + 0.8;
00E) Preferred sodium mole fraction of 8B and 4.
For Oma+ arc tube diameter, the required arc length is 2
4.5 mm, which gives the preferred lamp indicated by the asterisk on FIGS. 1-3.

For a 90-volt, 50-watt high-pressure sodium lamp, Q = 3.96 + 11.76x + 2.8;
Therefore, the preferred sodium mole fraction of 0.686 and 4. For the arc tube diameter of Oll, the required arc length is 26.51-.

For a high pressure sodium lamp of 70 volts and 50 watts, Q = 3. pd +11.76x -1,2,
Therefore, for a preferred sodium mole fraction of 0.686 and an arc tube diameter of 4.011, the required arc length is 22.51-.

These 'formulas are believed to give arc lengths in the range of 0.151 m, and this value of 0.15II1 m is
It is well within the desired manufacturing tolerance, which is typically on the order of ±0.51 Im.

In manufacturing, the arc tube diameter can be finished to tighter tolerances and the sodium mole fraction is inherently more precise. However, as can be seen by studying the drawings, small changes do not significantly affect efficiency.

Therefore, in determining the scope of the present invention, it is not intended to be construed as being limited to the precision within which the formula can be evaluated.

FIG. 4 shows a preferred 50 watt, 80 volt high pressure sodium lamp in accordance with the present invention. The polycrystalline alumina discharge tube 1 has a length of 24.5 mm plus the length of two electrodes (in this example, the total length is 36.3 sm).

The discharge tube has an internal diameter of 4.011 mm and is equipped with an end cap 2 for attaching electrodes (not shown) and an external lead 3. The discharge tube 1 was filled with a xenon starting gas of 20 torr at a cold fill pressure and a sodium mole fraction of 0.686.
Filled with a filling containing amalgam. The assembly is mounted within an outer envelope 4 and a conventional metal frame 5.
supported internally by A typical lamp base 6 is provided with terminals 7.

The preferred 70 volt and 90 volt lamps are substantially identical except that the arc tube lengths are 10% shorter and 10% longer, respectively.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the influence of arc tube diameter on efficiency. FIG. 2 is a graph showing the effect of sodium mole fraction on efficiency. FIG. 3 is a graph giving the arc length required to optimize efficiency as a function of arc tube diameter, lamp voltage and sodium mole fraction. FIG. 4 depicts a preferred 80 volt high pressure sodium lamp constructed in accordance with the present invention. 1...Discharge tube 2...End cap 3...
External lead 4...Outer envelope 5...Metal frame 6
・・・Lamp base

Claims (4)

[Claims] (1) A voltage sodium lamp for operation with a rating of 50 watts and a lamp voltage drop of 70 volts to 130 volts, having an inner diameter of 3.0 to 5.0 volts. Olm comprises a substantially cylindrical light-emitting arc tube with sealed thermionic electrodes at both ends thereof and an inert starting gas and a between the electrodes, where d is the inner diameter of the arc tube, X is the sodium mole fraction, and V is the lamp voltage drop in volts. The arc length Q(II) of is ゛, Q = 3,9d +11.76x+ 0.20 V-
A high-pressure sodium lamp characterized by a 15.2-hour supply. (2) A high-pressure sodium lamp according to claim (1), wherein the arc tube wall load is limited to less than 20 W/cm2. (3) A high pressure sodium lamp according to claim 1 or 2, wherein the sodium mole fraction is on the order of 0.7. (4) Takasho sodium having a sodium molar fraction of 0.686-(-) according to claim (3);
lamp. (2) The Takatsuji sodium lamp according to any one of claims (1) to (4), wherein the arc tube diameter is substantially 4.0 mm. ■ 90 whose arc tube diameter is 26.5±0.5111m
The high-pressure sodium lamp 5 according to any one of claims (3) to (5), which is a volt lamp; A high-pressure sodium lamp according to any one of claims (3) to 0, which is a lamp. ■ Claim No. 3, which is a 70 por 1- lamp with an arc tube and a diameter of 22.5±0.5IIIl.
The high-pressure sodium lamp according to any one of items (5) to (5).