JPS5971249A - High pressure sodium vapor lamp - Google Patents

Abstract

PURPOSE:To aim at a distinct improvement in color rendering properties, by increasing the weight ratio of sodium to mercury being sealed in a luminous tube more than the specific value, and raising the sealing pressure of xenon gas up higher than the specific value too. CONSTITUTION:Those of sodium, mercury and xenon gas are all sealed up in a luminous tube 3 carrying electrodes at both end parts to be housed in an outer tube 1 of a high pressure sodium vapor lamp, while the ratio of sodium to mercury (Na/Hg) is increased to more than 3.5 at a weight ratio, and the sealing pressure of the xenon gas is made so as to be raised up to more than 450 torr. Therefore, with the ratio Na:Hg raised, an average color rendering index Ra is enhanced, while the average color rendering index Ra can be increased in proportion to an increase in the xenon gas sealing pressure, setting the Ra down to more than 75, thus a high pressure sodium vapor lamp excellent in color rendering properties can be secured.

Description

[Detailed description of the invention] Field of use for work The present invention relates to high pressure sodium lamps.

Conventional structure and problems High-pressure sodium lamps have electrodes at both ends, and are highly efficient because they have an arc tube that is filled with rare gases such as sodium, mercury, and xenon gas. For this reason, it is attracting attention as a lamp suitable for the energy-saving era.

2/] It is well known that the lamp efficiency of such a high-pressure sodium lamp can be increased by increasing the pressure of the xenon gas sealed in the arc tube, and the Journal of the Institute of Illuminating, Vo7++64, A10.

1980, pp. 61-58, the average color rendering index Ra is
A high-pressure sodium lamp with Ma=60 has been shown to be useful in improving this.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a high-pressure sodium lamp with further improved color rendering properties.

Structure of the Invention The present invention is as follows: Ratio of IJum to mercury (Na/f(g)
The weight ratio of mercury to sodium is significantly increased to 3.5 or more, and the pressure of filling xenon gas is increased to 450.
The color rendering properties are improved by significantly increasing Torr or more.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 1 shows a high-pressure sodium lamp, in which 1 is an outer 3-page tube, 2 is a stem wire, and 3 is an arc tube made of polycrystalline alumina, with an inner diameter of 8.5 ran and a distance between electrodes of 60 mm. is equipped with electrodes, and inside contains 24 mg of sodium, 6 mg of mercury, and xenon glass.
orr is enclosed.

A thermal protection film 4 made of, for example, metal foil is provided on the outer walls of both ends of the arc tube 3 to keep the coldest point warm.The inside of the outer tube 1 is kept in a vacuum by a getter 5. Standing.

In addition, in the figure, 6 is a base.

When this lamp was turned on with an input power of 400 W, it exhibited high color rendering with an average color rendering index IRa of 78 and a color temperature of 2480.

Using an arc tube with the same dimensions as the arc tube shown in the above example, the pressure of xenon gas sealed was 520 Torr, and the ratio of mercury to sodium (Na/Hcr) was varied in five levels as shown in Table 1. When a high-pressure sodium lamp was manufactured and turned on, and the average color rendering index Ra was measured, the results were as shown in the table.

Table 1 (US: Total amount: 30 mg) Next, using an arc tube with the same dimensions as the arc tube shown in the above example, Na / Hg was adjusted to 4. o (total amount 30 mg) constant, and the pressure of xenon gas filled in was changed to four levels as shown in Table 2. High-pressure sodium lamps were manufactured and lit, and the average color rendering index Ra was measured. The results are shown in Table 2. The result was as expected.

From Table 2, it can be seen that the average color rendering index Ra increases monotonically as the pressure of the xenon gas increases.

Effects of the Invention As explained on page 5, the present invention includes filling sodium, mercury, and xenon gas in an arc tube equipped with electrodes at both ends, and adjusting the ratio of sodium to mercury (N a /Hg
) at a weight ratio of 3.6 or more and a xenon gas filling pressure of 450 Torr, it is possible to provide a high-pressure sodium lamp with high color rendering properties and an average color rendering index Ra of 75 or more.

[Brief explanation of drawings]

The figure is a front view of a high-pressure sodium lamp.
... Outer tube, 2 ... Stem wire, 3 ... Arc tube, 4 ... Heat protection film, 5 ... Getter, 6 ...・Cap.

Claims (1)

[Claims] Sodium in an arc tube with electrodes at both ends. A high-pressure sodium lamp characterized in that mercury and xenon gas are sealed, the weight ratio of the sodium to the mercury is 3.5 or more, and the pressure of the xenon gas is 450 Torr or more.