JPS60225346A - Low pressure mercury vapor discharge 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 comprises a discharge vessel consisting of at least two parallel tube sections vacuum-sealed, disposed close to each other and in communication with each other near one end; A discharge path is formed within the tube section between the electrodes provided at the other end of the tube section during operation of the lamp, this discharge path being curved in at least one section, and the discharge vessel is arranged between the electrodes provided at the other end of the tube section during operation of the lamp. It concerns a low-pressure mercury vapor discharge lamp formed in such a way that a part of the inner wall has a relatively low temperature in its original location near the communication part of the lamp.

Such a lamp is known from British Patent Specification No. 2,050,046.

This known lamp is relatively compact and is used to replace incandescent lamps for general lighting purposes.

If the electrical energy applied to such a lamp is increased, or if the lamp is operated in a space (e.g. in a small luminaire) at a temperature above normal room temperature, the light output will still remain relatively high. dripping The mercury vapor pressure within the discharge vessel is stabilized at a virtually optimal value (approximately 1 O-2 torr) due to the presence of a cooler section within the discharge vessel near the end of the tube section.

However, it has been found that under normal operating conditions, mercury condensation tends to occur in colder temperature areas within the discharge vessel.

This is particularly disadvantageous if the lamp is arranged in a vertical position with the electrodes at the lower end of the lamp.

In this case, there is a risk that the mercury will fall along the inner wall of the discharge vessel, thereby damaging the phosphor layer on the inner wall of the discharge vessel. This not only results in a loss of light output, but also detracts from the appearance of the lamp. Furthermore, liquid mercury falls in the form of water droplets and impinges on the helical filament of the electrode.

This has a detrimental effect on the operation of the lamp. Moreover, as this phenomenon occurs, the light output fluctuates and the light intensity distribution on the surface of the discharge vessel becomes non-uniform.

The object of the invention is to obtain a lamp which has a high light output and which does not suffer from the disadvantageous phenomena mentioned above.

According to the invention, the low-pressure mercury vapor discharge lamp mentioned at the outset is characterized in that the discharge vessel contains an amalgam therein which controls the mercury vapor pressure in the discharge vessel during operation of the lamp.

In the lamp of the invention, the undesirable phenomena mentioned above do not occur. The mercury vapor pressure is controlled in the discharge vessel by the amalgam under normal operating conditions, so that no mercury condensation occurs in the cooler parts of the discharge vessel. Furthermore,
The mercury vapor pressure during operation of the lamp is stabilized at a value of approximately 1 O-2 Torr over a wide temperature range. In this case, the light output of the lamp is kept as high as possible, even if the lamp is operated in a relatively hot location, such as in a luminaire.

Preferably, the amalgam is in an area behind one of the electrodes. A suitable area is, for example, the so-called base of the given piece. Such a mount is not only provided with an electrode, but also, for example, with a conductor for this electrode as well as with an exhaust pipe behind the electrode, which is used for evacuation of the discharge vessel.

In a preferred embodiment of the invention, the amalgam consists of an alloy of evanidium and mercury or an alloy of indium, bismuth and mercury (for example British Patent Specification No. 15).
0363'6). Favorable results have been obtained with an amalgam consisting of bismuth, lead, tin and mercury (see eg GB 1572657).

The discharge vessel of the lamp according to the invention can have various forms. The discharge vessel is e.g.
It may have two tube sections interconnected by a cross-communication, as described in No. 46. However, it is also possible to alternatively have four tube sections connected in this way. Good results have also been obtained with lamps having a discharge vessel of the type described in DE-A-31 12 878. In this lamp, the low wall temperature portion is obtained by forming the discharge tube, whose curved portion is U-shaped, in such a way that a wall portion whose cross section extends approximately at right angles to the axial direction is obtained.

The invention will now be explained in more detail with reference to the accompanying drawings.

In the figure, the lamp has a vacuum-sealed discharge vessel (filled with mercury and a rare gas such as argon) consisting of two parallel tube sections 1 and 2. Said tube sections are arranged close to each other and communicated with each other by means of cross-connections 3. The inner walls of the tube sections and cross-connections are coated with a fluorescent layer. Said cross-connection may be described, for example, in British Patent Specification No. 204.
8562. This cross-communication is located at one end 4 and 5 of the tube sections 1 and 2.
located at a distance from each other. Said end is arranged in the form of an end face at right angles to the longitudinal axis of the tube section. Electrodes 6 and 7 are respectively arranged next to each other at the other end of each tube section. During operation of the lamp there is a U in the tube section 1 and 2 between said electrodes.
A shaped discharge path is created.

A lamp cap 8 is attached to the ends of the tube sections 1, 2 at the electrodes, and is preferably made of synthetic resin. The lamp cap has a protruding wall portion 9
and a starter is provided within the projecting wall portion.

Connecting pins 0 and 11 are provided on both sides of the protruding wall portion.

During operation of the lamp, the discharge vessel wall section near one end of the tube section (particularly 4.5) is relatively cool. Unless additional measures are taken, condensation of mercury will occur in these areas, with the disadvantages mentioned above, especially if the lamp is placed in a vertical position.

To prevent such phenomena, an amalgam 13, which controls the vapor pressure in the discharge vessel during operation of the lamp, is located in the exhaust pipe 12 behind the electrode 6, which forms part of the mount for the electrode 6. The end opposite to the electrode 6 is sealed. Condensation of mercury at the aforementioned ends is avoided in this case.

Preferably, the amalgam-forming alloy with mercury consists of lead, bismuth and tin.

In the practical example of the lamp described above, the length of the tube section is approximately 1
3cn+, the inner diameter is approximately in the order of 10. The phosphor layer on the inner wall is a mixture of two fluorophores: a green-emitting terbium-activated cerium magnesium aluminate and a red-emitting trivalent europium-activated yttrium oxide. Atomic ratio of lead, bismuth and tin is 16+36.5:4
180 mg of alloy 7.5 is in the exhaust pipe. Additionally, approximately 6 mg of mercury is present. Using an argon filler (3 torr) as the rare gas, the light output was approximately 600 lumens with approximately 9 W of lamp power.

[Brief explanation of the drawing]

The drawing is an elevational view, partially in section, of an embodiment of the low-pressure mercury vapor discharge lamp of the present invention. 1.2... Pipe part 3... Cross communication part 4.5...
End of tube part 6.7... Electrode 8... Lamp cap 9... Wall protruding part 10.11... Connection pin 13
...Amalgamales I, gall, 1

Claims (1)

[Claims] 1. A discharge vessel consisting of at least two parallel tube sections vacuum-sealed and disposed close to each other and in communication with each other near one end; , during operation of the lamp a discharge path is created between the electrodes provided at the other end of the tube sections, this discharge path being curved in at least one area, and the discharge vessel is provided with a communication between the tube sections during operation of the lamp. In low-pressure mercury vapor discharge lamps formed in such a way that part of the inner wall has a relatively low temperature in the original location nearby,
Low-pressure mercury vapor discharge lamp, characterized in that the discharge vessel contains therein an amalgam which controls the mercury vapor pressure within the discharge vessel during operation of the lamp. 2. A low-pressure mercury vapor discharge lamp as claimed in claim 1, wherein the amalgam is in the area behind one of the electrodes. 3. The low-pressure mercury vapor discharge lamp according to claim 2, wherein the amalgam is in an exhaust pipe provided behind the electrode. 4. The low-pressure mercury vapor discharge lamp according to claim 1, 2 or 3, wherein the amalgam is comprised of lead, tin, bismuth and mercury.