JP3026813B2 - Metal halide lamp - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a metal halide lamp in which a luminescent metal is sealed in the form of a halide.

[Conventional technology]

In the metal halide lamp, a luminous metal is enclosed in the arc tube in the form of a halide in addition to mercury and a rare gas, and the starting operation is as follows.

First, a rare gas discharge occurs, and the heat causes the vapor pressure of mercury to increase, causing a transition to mercury discharge. The metal halide also vaporizes as the temperature of the lamp increases, and is excited by mercury discharge to produce a spectrum unique to the metal halide.
Thereby, luminous efficiency and color rendering are improved.

However, when a low-pressure rare gas is sealed, the luminous flux at the time of rare gas discharge is small as shown in FIG. 2, and the time until a sufficient luminous flux is obtained becomes long.

For this reason, a rare gas is sealed at a high pressure so that a sufficient luminous flux can be obtained instantaneously (see FIG. 3).

[Problems to be solved by the invention]

However, conventionally, since a bromide or iodide such as Na, Tl, Sc, or Dy is encapsulated, the melting point is relatively high, the vapor pressure is low, and the light emission during rare gas discharge is not significantly contributed. Further, even if the rare gas is sealed at a high pressure, the luminous efficiency is poor due to the relatively high excitation voltage of the rare gas. To obtain a sufficient luminous flux, (a) the pressure of the rare gas is further increased. (B)
Take measures such as increasing the lamp input,
In the case of (a), there is a disadvantage that the starting voltage is increased, and in the case of (b), the life is shortened. Further, mercury has a slight vapor pressure even at room temperature, and contributes to light emission during discharge of a rare gas. However, there is a problem that it is difficult to obtain sufficient light emission due to a relatively high excitation voltage.

An object of the present invention is to provide a metal halide lamp capable of obtaining a sufficient luminous flux without deteriorating other characteristics.

[Means for solving the problem]

The present invention uses one or more of Ar, Kr, and Xe as a rare gas to be sealed in an arc tube together with mercury, and seals them at a gas pressure of 4 atm or more, and one or more kinds of iodides and bromides of Cr or Ti. As a metal halide in the arc tube.

〔Example〕

 Hereinafter, the present invention will be described in detail based on examples.

In this embodiment, mercury and a rare gas are sealed in the arc tube, and CrI ₂ is sealed as a metal halide. Xe gas is used as the rare gas, and the pressure is 4 atm or more.

When the pressure of the Xe gas is set to 4 atm or more, a sufficient luminous flux can be obtained from the initial stage of the start. This is confirmed from the test results (Table 1) of prototypes (Xe gas pressures are different and CrI ₂ is sealed and not sealed at the same pressure).

The conditions other than Table 1 (bulb shape, internal volume, electrode diameter, material, amount of mercury, distance between electrodes, etc.) were all the same.
As shown in FIG. ₁ , the maximum luminous flux at the time of stable discharge is h ₁ ,
The maximum luminous flux at the time of Xe gas discharge was defined as h ₂ and h = h ₂ / h ₁ × 100 (%), and h> 80% was used as a criterion for evaluation.

In the above example, Cr iodide was used, but when a prototype using another metal halide was tested,
Similar effects were obtained with Ti iodide.

The same effect can be obtained with bromide, and the rare gas
The same effect was obtained when changing to r.

Cr and Ti iodides and bromides have relatively low melting points,
Since the vapor pressure is high and the spectrum of the excitation voltage is relatively low in the visible region, very high light emission is performed at a low temperature. Therefore, it is considered that a desired luminous flux can be obtained without increasing the pressure of the Xe (or Ar, Kr) gas so much.

The reason that no significant effect could be obtained when the pressure of the rare gas was 3 atm or less was that sufficient thermal excitation and thermal ionization were unlikely to occur because the gas pressure was relatively low, so that Cr and Ti iodides This is probably because bromide cannot be excited sufficiently.

The reason why the iodide / bromide of In had little effect is considered to be that the melting point is relatively higher than that of Cr and Tr, and that the wavelength is shifted to a lower wavelength side.

〔The invention's effect〕

As described above, according to the present invention, while the pressure of the rare gas sealed in the arc tube together with mercury is set to 4 atm or more, iodide / bromide of Cr or Ti is sealed in the arc tube, so that the starting voltage and the service life are increased. Sufficient luminous flux can be obtained from the initial stage without affecting other characteristics.

[Brief description of the drawings]

FIGS. 1 to 3 are characteristic diagrams showing the relationship between the lighting time of the metal halide lamp and the luminous flux. h ₁ …… Maximum luminous flux during stable discharge h ₂ …… Maximum luminous flux during Xe gas discharge

Claims (1)

(57) [Claims] 1. Use of one or more of Ar, Kr, and Xe as a rare gas to be sealed in an arc tube together with mercury, and sealed at a gas pressure of 4 atm or more, and one or more of iodides and bromides of Cr or Ti. A metal halide lamp characterized in that seeds are enclosed in an arc tube as metal halide.