JPS60107257A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To make it possible to light up a lamp with DC current without causing any noticeable color separation and obtain a small-size, light-weight and low cost one by specifying the relation between the ratio of the inter-electrode distance of high-pressure sodium lamp luminescent tube to its inner diameter and the sodium vapor pressure in the luminescent tube when the lamp is lit up. CONSTITUTION:When the inner diameter of a high-pressure sodium lamp luminescent tube 1 is expressed as d(mm.), the distance between electrodes 2, 2' as l(mm.), and the sodium vapor pressure when lit up as Pna (KPa), the shape of the luminescent tube, the enclosed materials, and the lit-up conditions are specified to satisfy the equation Pna>=6.0(l/d-5.8). In this way, the discharge gas will have no part in which an amount of sodium is extremely small, and therefore the sodium luminescence can occur uniformly all through the luminescent tube, causing no noticeable color separation in the luminescent tube.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ignition device for high-pressure sodium lamps.

Prior Art Constructions and Problems Discharge lamps are usually powered through an inductive ballast or ballast. This is because discharge lamps require a current limiting element with negative voltage-current characteristics. However, inductive ballasts are heavy, hindering the path to making ballasts smaller and lighter.

In recent years, progress has been made in making ballasts smaller and lighter by lighting discharge lamps at high frequencies.

However, when a discharge lamp is lit at a high frequency, a phenomenon called acoustic resonance occurs at a frequency unique to the lamp, making the arc unstable. A number of methods have been proposed to prevent acoustic resonance phenomena, but each has its own advantages and disadvantages, and none have yet been put to practical use.

There is also a method of lighting a discharge lamp with direct current, but it has been said that lighting a discharge lamp with direct current causes a cataphoresis phenomenon, which causes color separation within the arc tube.

OBJECTS OF THE INVENTIONObject 1d of the present invention is to provide a compact, lightweight, and inexpensive discharge lamp lighting device that lights a high-pressure sodium lamp with direct current without causing significant color separation.

Constituent Structure of the Invention A discharge lamp lighting device is provided with a DC power source, a safety device connected between the terminals of the DC power source, and a high-pressure sodium lamp, and the arc tube of the high-pressure thorium lamp is connected to the arc tube with a distance between the electrodes of the arc tube. The relationship between the ratio R/d between fl Cnun] and tube inner diameter d [ll1m] and the sodium vapor pressure PnaCKPa] in the arc tube during lamp lighting is PNa≧e, o
(1/d -5,8)/This is characterized in that significant color separation due to the cataphoretic phenomenon in direct current lighting is prevented.

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

FIG. 1 shows an example of the structure of a high-pressure sodium lamp used in the present invention. In FIG. 1, 1 is an alumina ceramic arc tube, and 2' is an electrode.

A predetermined amount of sodium and mercury is contained in the arc tube.

In addition, xenon gas, argon gas, neon gas, etc. are sealed as a starting rare gas.

As another example of an arc tube, metal foil may be wrapped around both ends of the tube near the electrodes in order to increase the sodium vapor pressure during lighting.

FIG. 2 shows a circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention. In Figure 2, 3 is an AC power supply, 4 is a rectifier circuit, 5 is a smoothing capacitor, 6 is a DC power supply, 7 is a lamp current limiting resistor, 8 is a ballast, and 9 is a distance between electrodes 1 [
The high-pressure sodium lamp shown in FIG. 1 has an arc tube with a tube inner diameter of d [+nm].

Inside the high-pressure sodium arc tube, the sodium vapor pressure Pna [: KP a ,] during lighting is P ≧6.0.
(1/d-5,8), sodium mercury; 1.・Inner diameter dCπm of a 3° arc tube filled with xenon, neon, or argon gas as a rare gas for starting, the distance between electrodes 2, and the sodium vapor pressure inside the arc tube during lighting pna[ KP a ]
Explain the relationship between

inner diameter of the arc tube dummy] and electrode ratio 1i:lL'
n C111111] and high-pressure sodium lamps with different rated color temperatures are lit with DC current at various lamp powers.
As shown in Figure 3, the sodium vapor pressure Pn inside the arc tube
a[KPa] is Pna(6,0(ff/d-5,0)
In the region where Pna≧ey, o (R/d −5
, s), no noticeable color separation or cataphoresis phenomenon occurs.

From this, the ratio of the inner diameter d [: mml] of the arc tube of the high-pressure sodium lamp to the interelectrode distance Q [+nm] is 1/d.
and the sodium vapor pressure during lighting PnaCKPa] is Pna≧6. By setting the shape of the arc tube, the filling material, and the lighting condition so that the ratio is ○(3/cl-5,8), the high-pressure sodium lamp can be lit with direct current without any problem of color separation in practical use.

In this way, the reason why remarkable color separation due to the cataphoresis phenomenon does not occur is that the inner diameter d of the arc tube is
Even if diffusion and convection are not easy because π+lI<
d by a predetermined amount or more.

That is, when a high-pressure sodium lamp is lit with direct current, in the discharge electric body, (1) sodium ions are mainly attracted to the cathode by the electric field, and (2)
) Because the sodium ions attracted to the cathode increase the amount of thorium near the cathode, 1(('Jl・'
Diffusion of sodium from the 5f section towards the anode section:
1. - and (3) movement of thorium due to convection within the arc tube, and the above movements of sodium in (1) to (3) are balanced, creating a density gradient in the sodium in the discharge body.

However, in the high-pressure sodium lamp of the present invention, the tube inner diameter d is small relative to the distance 2 between the electrodes of the arc tube, and the above (2)
Even when diffusion and (3) convection are reduced and the density gradient of sodium in the discharge body becomes large, the sodium ion "Na" is changed to "Namie" with respect to the N/d of the arc tube.
o(R/d-6,8) to prevent a portion where thorium becomes extremely low in the discharge body.

Instead, the luminescence can be generated throughout the arc tube, so that no noticeable color separation occurs in the arc tube.

As explained above, for the ratio R/d of the inner diameter d (mm) of the arc tube and the interelectrode distance Q [mm], the sodium vapor pressure during lighting is ``na≧6.○(II/d- 5,8)
By using a high-pressure sodium lamp, it is possible to perform direct current lighting without causing significant color separation due to the cataphoresis phenomenon, and it is possible to provide a small, light, and inexpensive ballast.

However, in high-pressure sodium lamps, if the distance between the electrodes 2 is large relative to the normal inner diameter d of the arc tube, it is necessary to increase the lamp power in order to obtain the sodium vapor pressure necessary to emit the desired light. be.

However, the lamp power is large and '+h 41
W l+','.

If the distance l is large, the tube wall temperature at the center of the arc tube will be high. As a result, the amount of thorium lost from the arc tube increases, which reduces the lamp's lifespan.

becomes worse. In addition, when the tube inner diameter d is small compared to the normal electrode tube distance of the arc tube, in order to obtain the thorium vapor pressure necessary for the specified luminescence, the tube wall load (- lamp power / tube wall surface area) need to be increased. As a result, the tube wall temperature increases, and the lamp life characteristics deteriorate as described above. That is, when the ratio fi/d of the distance 2 between the electrodes of the arc tube and the inner diameter d of the tube increases, there is a problem that the lamp life characteristics deteriorate in order to obtain a predetermined light emission.

However, if μ/d of the arc tube is set to n/d (1o), a lamp with no practical problems can be obtained.

In this embodiment, a rectified AC power source 1 is used as the DC power source 4, but it may be composed of individual sources.
It may simply be a DC power source such as a storage battery, or it may also serve as the stabilizer 6. Unfortunately, the output voltage of the DC power supply 4 may be smoothed or pulsating. It's a size.
Although the resistor 5 is used as the ballast 6, other resistors may be used as long as they limit the lamp current, a light bulb may be used, or a DC
Needless to say, a switching device such as a chopper or an inverter may also be used. Alternatively, a lamp starting device may be connected to the ballast.

1. High-pressure sodium lamps, whether they are efficiency-oriented or color-rendering-improved types, are color-rendering-oriented as long as they are designed to produce a sodium vapor pressure that causes self-absorption and broadening of the sodium D resonance line at rated input. It can also be something shaped.

Effects of the Invention As described above, the discharge lamp lighting device of the present invention is capable of lighting a high-pressure sodium lamp under direct current without causing noticeable color separation due to the catahorence phenomenon, and the ballast can be made compact, lightweight, and inexpensive. I can do it.

[Brief explanation of drawings]

Fig. 1 is a partially sectional front view of a high pressure sodium lamp used in a discharge lamp lighting device according to an embodiment of the present invention, Fig. 2 is a circuit diagram of the same device, and Fig. 3 d is an arc tube in a high pressure sodium lamp of the same device. The ratio f between the interelectrode distance d and the tube inner diameter d
FIG. 3 is a characteristic diagram showing the relationship between l/d and the sulfur/lium vapor pressure Pna during the dogetsu period. 1... AC power supply, 2... Rectifier circuit, 6
... Ballast, 9... High pressure thorium lamp. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2

Claims (2)

[Claims] (1) A DC power supply, a ballast connected to the output terminal of the DC power supply, and a high-pressure sodium lamp connected to the DC power supply via the ballast, and electrodes of the arc tube of the high-pressure sodium lamp. Distance A (mm) and pipe inner diameter d [
] Ratio I1. /d and the sodium vapor pressure inside the arc tube during lighting PnaCKPa], Pna≧e,
A discharge lamp lighting device set to o (fl/d - s, s). (2) Distance between the electrodes of the arc tube 2 [double] and tube inner diameter cl (+n
Ratio with n mouth f! , /d is N/d(1o), the discharge lamp lighting device according to claim 1.