US3154713A

US3154713A - High intensity short arc lamp

Info

Publication number: US3154713A
Application number: US180421A
Authority: US
Inventors: Norman C Beese
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-03-15
Filing date: 1962-03-15
Publication date: 1964-10-27
Anticipated expiration: 1981-10-27

Description

Oct. 27, 1964 N. c. BEESE HIGH INTENSITY SHORT ARC LAMP Filed March 15, 1962 INVENTOR. NORMAN C. BEESE g. MM ATTORNEY United States Patent Ofi ice 3,154,713 Patented Oct. 27, 1964 This invention relates to electrical discharge lamps and more particularly to high pressure, high current gas or vapor discharge short are lamps which are constructed to provide desired acoustical resonance properties to be operative in optical communications systems.

Lamps of the short are type are known to the prior art -2ihd in general are constructed of a material capable of withstanding high temperatures and to provide a chamber for gases, such as argon, xenon, neon, etc., with or without mercury or other vapor additives, and within which are located electrodes for forming the arc.

Operation of short arc lamps on AC. power in the audio-frequency range or on D.C. power modulated by AC. currents may be affected by sound vibrations produced within the gas chamber which are caused by thermally induced variations in gas pressure that result from changes in current density in the arc. At certain critical frequencies, acoustical resonance of appreciable intensity may be built up by reflections from the bulb walls causing distortion or instability of the are which often results in extinction of the arc. In lamps of generally cylindrical shape, the critical frequencies are primarily caused by sound energy reflected from the ends of the lamp structure while in lamps of spherical shape, the sound waves spread to the lamp walls and are then focused or directed back upon the arc to produce instability at the electrodes.

The broad object of the invention is to provide a short arc lamp which is constructed in a manner to eliminate or minimize the effect of acoustical resonance on the arc stream when a resonant frequency is used to operate or modulate the arc in order to permit the lamp to be used over extended periods of time.

Another object of the invention is to provide a short are lamp in which provision is made to prevent deleterious acoustical resonance which is developed when the lamp is operated or modulated by a resonant frequency from interfering with the arc stream.

Another object of the invention is to absorb the deleterious acoustic resonance developed when the lamp is operated or modulated by resonant frequencies in order to prevent their interfering with the arc stream.

Another object of the invention is to equip one or both of the electrode structures with a medium for absorbing deleterious acoustical resonance which is developed when the lamp is operated or modulated by a resonant frequency.

Another object of the invention is to modify the lamp structure by the provision of a zone therein for concentrating acoustical energy when the lamp is operated or modulated by resonant frequencies in order to prevent interferences with the arc stream.

Other and more detailed objects of the invention will become apparent from a better understanding of the invention, which may be had from the accompanying drawings and description thereof.

FIG. 1 is a longitudinal sectional view of a short are lamp showing one embodiment of the invention for absorbing acoustical vibrations and preventing them from interfering with the arc stream;

FIG. 2 is a longitudinal sectional View showing a modification of FIG. 1.

Referring to FIG. 1, a gaseous discharge lamp of the short arc type with which the present invention is adapted to be used is generally designated by the reference 10 and is constructed of clear fused quartz and provides strong wall structure for withstanding the high temperatures and pressures encountered during operation. The lamp is shaped to provide a central envelope section 12 and outer sections 14-14 which respectively are equipped to form the anode and cathode structures of the lamp. The components for each of the anode and cathode structures are generally similar and differ only in the particular design of the anode electrode 15 and the design of the cathode electrode 16. Since the components of the anode and cathode structures are generally similar, only the anode section will be described in detail to provide an explanation of the manner of assemblying the components and their positional arrangement within the lamp 10.

The anode electrode 15 is constructed of tungsten and is mounted at the inner end of a tungsten rod 17 while a quartz collar 18 is positioned on the rod adjacent its outer end and the outer end is secured in a quartz coupling block 19. Another tungsten rod 20 has its inner end secured in the opposite end of the coupling block 19 While its outer end extends through a glass closure 21 to receive leads 22 by means of a connector 23. Conductors in the form of thin molybdenum ribbons 24 are suitably secured about the rod 20 and extend along the coupling block 19 and are received between the first tungsten rod 17 and the collar 18. After assembling the anode components, as described, the outer section 14 of the quartz envelope is shrunk on to the coupling block 19 and collar 18 to provide an integral structure; end closure 21 is secured to the section 14 by means of a quartz to glass seal indicated at 25.

The quartz coupling block and quartz collar arrangement for mounting the

tungsten conductors

17 and 20 provide strength to the lamp structure While the conductor ribbons 24 provide for the transmission of heavy current loads from the leads 22 to the anode electrode 15. In the drawing the similar components of the cathode are identified similarly to those of the anode.

In FIGS. 1 and 2, the discharge are between the anode 15 and cathode 16 is shown located ofif the geometric center of the central section 12 of the lamp and toward the cathode section 14 of the lamp. Although this is a preferred lamp construction, it will be understood that the detailed structure of the invention which will now be described has utility with lamps in which the discharge arc has a different location.

According to the present invention, improvement in the performance of the above disclosed lamp can be obtained by the provision of sound absorbing means adjacent the electrode ends of the central section of the lamp and in the provision of an enlarged zone in the central section for eliminating or minimizing acoustical resonant frequency when the lamp is operated or modulated.

In each of FIGS. 1 and 2, the central section 12 of the lamp is provided with an enlarged circumferential bulge or protrusion 29 in general alignment with the tip of cathode electrode 16. This bulge or protrusion is arcuate as shown and forms a zone which is transversely spaced from the discharge are and in which the reflected acoustical energy can become concentrated resulting in effect in the scattering of the primary resonant frequency throughout the envelope and preventing it from being reflected back to the arc stream as an echo phenomenon.

In FIG. 1, in addition to the bulge or protrusion 29 a disk or diaphragm 30 is mounted transversely of the tungsten conductor rod 17 rearwardly of the cathode 16 and adjacent the cathode end of the lamp central section. The diaphragm has its peripheral edge transversely spaced from the wall of the central section and also provides an axial space with the collar 18. The axial space receives means for absorbing acoustical energy in the form of a cylinder 31. Both'the disk or diaphragm 30 and the cylinder 31 are preferably formed of thin material, for example sheet metal, and are united to provide a unit which has apertures 32 in the diaphragm and apertures 33 in the cylinder which admit the energy reflected from the walls of the lamp central section into the space formed by the unit; A lamp incorporating this sound absorbing element gave good results and had only slight acoustical resonance below 12,000 c.p.s. modulation. Although not shown in FIG. 1, the anode 15 of the lamp may be provided with a similar energy absorbing arrangement which would be disposed generally between the bushing 18 and 'the anode 15 of the anode section .14.

In the modification of FIG. 2, both the anode and cathode sections 14 and 14' are shown provided with a somewhat different arrangement for absorbing acoustical energy. A diaphragm or disk 40 which is similar in size and shape to the diaphragm or disk 30 but preferably is formed of quartz is fixedly mounted about each of the tungsten conductors 17 providing axial spaces at both the cathode and anode ends of the central section 12 with the collars 18. The spaces receive an energy absorbing material such as quartz or wire wool 41 while the diaphragm 40 is provided with apertures in a manner similar to that of diaphragm or disk 30 of FIG. 1. The quartz or wire wool being porous provides along with the disk an absorbent structure or unit having openings which permit the passage of energy in a manner similar to that of the apertured disk and cylinder unit of FIG. 1.

'Both the sound wave absorbing constructions of FIGS. 1 and 2 provide arrangements for the absorption of the reflected sound waves which are not concentrated in the circular bulge 29. A lamp constructed as shown in FIG. 1 was operated at high power loading and showed only two feeble resonance frequencies when modulated below 12,000 c.p.s.

It should be understood that the foregoing disclosure shows only preferred embodiments of the invention and that it is intended to cover all modifications of the embodiments herein described which do not depart from the spirit of the invention.

I claim:

1. An electric discharge lamp comprising a light transmissive central chamber disposed between end electrode sections each having mounting structure for a conductor, a first conductor extending axially of one electrode section and positioning an anode electrode within the central chamber, a second conductor extending axially of the other electrode section and positioning a cathode electrode Within the central chamber, said electrodes having their front ends spaced to provide an arcing gap therebetween, a first rear space between the rear endof one electrode and the mounting structure of one electrode section and a second rear space between the rear end of the other electrode and the mounting structure of the other electrode section, means for preventing acousticahenergy which is reflected from the walls of the central chamber" from interfering with said arcing gap which comprises a unit formed of a perforated disk and an absorbing element, said perforated, disk being mounted in one of said rear spaces concentrically of one conductor and said ab-' the absorbing element being formed of a wool-likepack ing material. I

7 References Cited in the file of this patent UNITED STATES PATENTS Kraus et a1. July 8, 1913 Beese Oct. 24, 1961

Claims

1. AN ELECTRIC DISCHARGE LAMP COMPRISING A LIGHT TRANSMISSIVE CENTRAL CHAMBER DISPOSED BETWEEN END ELECTRODE SECTIONS EACH HAVING MOUNTING STRUCTURE FOR A CONDUCTOR, A FIRST CONDUCTOR EXTENDING AXIALLY OF ONE ELECTRODE SECTION AND POSITIONING AN ANODE ELECTRODE WITHIN THE CENTRAL CHAMBER, A SECOND CONDUCTOR EXTENDING AXIALLY OF THE OTHER ELECTRODE SECTION AND POSITIONING A CATHODE ELECTRODE WITHIN THE CENTRAL CHAMBER, SAID ELECTRODES HAVING THEIR FRONT ENDS SPACED TO PROVIDE AN ARCING GAP THEREBETWEEN, A FIRST REAR SPACE BETWEEN THE REAR END OF ONE ELECTRODE AND THE MOUNTING STRUCTURE OF ONE ELECTRODE SECTION AND A SECOND REAR SPACE BETWEEN THE REAR END OF THE OTHER ELECTRODE AND THE MOUNTING STRUCTURE OF THE OTHER ELECTRODE SECTION, MEANS FOR PREVENTING ACOUSTICAL ENERGY WHICH IS REFLECTED FROM THE WALLS OF THE CENTRAL CHAMBER FROM INTERFERING WITH SAID ARCING GAP WHICH COMPRISES A UNIT FORMED OF A PERFORATED DISK AND AN ABSORBING ELEMENT, SAID PERFORATED DISK BEING MOUNTED IN ONE OF SAID REAR SPACES CONCENTRICALLY OF ONE CONDUCTOR AND SAID ABSORBING ELEMENT SURROUNDING THE CONDUCTOR AND EXTENDING FROM THE DISK TO THE MOUNTING STRUCTURE OF THE ELECTRODE SECTION.