US2774905A - Induction lamp - Google Patents
Induction lamp Download PDFInfo
- Publication number
- US2774905A US2774905A US520767A US52076755A US2774905A US 2774905 A US2774905 A US 2774905A US 520767 A US520767 A US 520767A US 52076755 A US52076755 A US 52076755A US 2774905 A US2774905 A US 2774905A
- Authority
- US
- United States
- Prior art keywords
- target
- disc
- opening
- light
- concentrator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/04—Electrodes; Screens; Shields
- H01J61/10—Shields, screens, or guides for influencing the discharge
- H01J61/106—Shields, screens, or guides for influencing the discharge using magnetic means
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01K—ELECTRIC INCANDESCENT LAMPS
- H01K11/00—Lamps having an incandescent body which is not conductively heated, e.g. heated inductively, heated by electronic discharge
Definitions
- This invention relates to electric lamps, and especially to lamps in which light is emitted by an incandescent body.
- Such lamps have previously been either of the pointsource arc-heated type or of the wire filament type, neither of which is satisfactory for use when a uniformly illuminated field is desired for projection devices, iilm printers and the like.
- incandescent lamps are generally used for such purposes, the lamp having a series of parallel filaments arranged side-by-side in a plane.
- the image produced by such a series of filaments is obviously non-uniform in brightness, and in order to reduce the non-uniformity, the system has to be defocussed, that is, the image is focussed at a point other than that at which the light is to be used.
- the socalled hlm gate is the position at which the light is desired, but the image of the filament has to be focussed at a position beyond the gate, so that the image is sufficiently lout of focus at the gate to blue it and give a more uniform light pattern.
- a light source of uniform brightness throughout its frontal luminous surface can be achieved by using as the light source an inductivelyheated body of refractory material, such as, for example hafnium carbide, tantalum carbide or niobium carbide, as shown in a copending application Serial No. 520,718, filed on July 8, 1955, by Sandford Christopher Peek, lr.
- the inductively heated body is referred to as a target
- the target can be heated inductively from a coil placed around it and carrying high frequency current.
- a field concentrator between the coil and the target is very effective in improving the eiciency of energy conversion to the target.
- a concentrator has been used in the form of a metal cylinder closed at one end except for an opening in which the target is placed.
- the cylinder is slotted longitudinally along its side, the slot extending radially into the closed end, in order to eliminate 2,774,905 Patented Dec. 18, 1956 2 any direct loop around the intensifier itself, transverse to the field.
- the frontal surface of the target was set flush with the plane of the frontal surface of the annular concentrator disc, or flush with the frontal edge thereof. I have found, however, that under such a condition, the extreme outside edge of the light pattern is less bright than that from the remainder of the frontal surface. l discovered that the difference in brightness between the extreme outside circumferential edge and the remainder of the face could be eliminated if the target were set so that its frontal surface was a short distance in front of the plane of the concentrator disc, if the latter were flat, or in general a short distance in front of the front edge of the inside opening in the concentrator disc.
- the loss in brightness of the circumferential edge of the target when the latter is not positioned according to my invention appears to be due to the formation of a smooth shiny surface on the cylindrical sides of the target in the neighborhood of the central opening in the concentrator disc.
- the smooth shiny surface has poorer radiating characteristics than the remainder of the target surface, and alters the heat distribution.
- the smooth shiny surface is confined to a region farther from the front circumferential edge of the target, and the radiation characteristics and brightness of the front surface of the target become uniform.
- the target extends into the opening in the concentrator disc, and in general will extend back to the back edge of the annular opening in the concentrator disc.
- Fig. l is a perspective view of one embodiment of the invention
- Fig. 2 is a profile section of the device of Fig. 1
- Fig. 3 is a cross section through the middle of the device.
- the glass envelope 1 includes the plane glass disc 2, of a type generally called an optical at, through which light from the cylindrical target 3 can emerge when the latter is heated by the passage of a high frequency current in coil 4, which is external to the lamp and not an integral part thereof.
- the target 3 is set in the central opening 5 of an annular metal disc 6, and is of smaller diameter than said opening.
- j disc 6 has the radial slot 7 so that there will not be a complete conductive turn in which current can flow by induction.
- the disc 6 acts as a closure member for one end of the cylindrical metal shell 8, which extends longitudinally back in the envelope 1, preferably for a distance equal to the length of the coil 4 and in register therewith.
- the slot 7 extends from disc 6 longitudinally down the wall of cylinder 8, to prevent the cylinders acting as a complete conductive turn, that is, as a so-called shorted turn.
- the disc 6 and shell 8 act to concentrate the magnetic field in the vicinity of the target.
- the ltubes 9, 9 should not extend across the slot 7 at any point, for if they did, they would short circuit it.
- the concentrator disc 6 and shell 8 can be supported in some other manner than by tubes 9,9, for example by being supported from the glass walls of envelope 1.
- the cylinder S is support-ed by the hollow metal tubes 9, 9 which are attached to the copper thimbles 10, 10 at the external ends 11, 11 thereof, said copper thimbles being sealed to the bottom wall 12 of the glass envelope 1 in a manner customary in the art of such seals, which are generally called housekeeper seals.
- the hollow tubes 9,9 terminate in the customary type of metal connectors 13, 13 used for sealing copper tubing together. Inside the envelope 1, the tubes 9, 9 extend around and across the inner Wall 14 of cylinder 7, being attached thereto by soldering or in some other convenient manner. y
- the hollow tubes 9,9 are not electrical lead-in conductors, but are merely conductors for the circulation of a cooling liquid such as water. if the water supply 1s grounded, however, the tubes 9, 9 and the cylinder S and discV 6' to" whichl they are thermally connected, will also be at ground potential.
- the thickness of target 3 is greater than that of the disc 6, and the target is placed so that part of it extends above the plane of the top of said disc.
- the target thickness was about 25132 inch and the disc thickness about 1/16 inch.
- the disc was about 2 inches in diameter. Beyond the :gg inch thickness of the target itself, the target piece was machined down to a diameter of about 1/16 inch to provide a projecting support i5 for the main portion of the' target 3, said supporting extending about 5%; inch back from said target itself.
- the diameter of the target 3 itself was 5/12 inch.
- the bottom end of projecting support i5 is .fitted into u zirconia supporting tube 16 at a considerable distance, about 1A inch in one example, from the main Itarget 3, in order to reduce heat losses.
- the zirconia tube extends downward along the axis of cylinder '7, and its lower end 17 is held in collar 18 by set screws i9, supported from the lower en'd of cylinder 7 in the bracket 2i), shown in Figure 3 held to said cylinder by the screw 25, or in some other convenient manner.
- Other refractory materials than zinconia can be used, the zirconia being given as an example.
- the whole internal unit or mount is thus supported from the Housekeeper seal thimbles l0, liti, set in the glass base of header 2?.
- the seals to the thimbles ifi, l@ can therefore be made before the glass header 21 is sealed to envelope l, the sealing being accomplished in a manner well-known in the art.
- the lamp can be exhausted in a manner usual in the art, through the metal exhaust tube 22 which is brazed to the side of one ofthe thirnbles 10.
- the tube can then be filled with argon at about 11/2 atmospheres absolute pressure, for example, and the exhaust tube 22 then sealed off to complete the lamp.
- the exhaust tube 22 being of metal, for example copper, can be flattened together at one part of its length to seal the lamp from the exhaust system, and then cut off at the flattened part. Such seals are wellknown in the art.
- one of the tubes 9 is connected to a water inlet by connector 13, and the other tube 9 is connected to a Water outlet by its connector. Water, or other cooling iluid, is then circulated through the tubes 9, thereby keeping the disc 6 and shell S cool.
- a high frequency source of say 4 megacycles although other frequencies can be used, is connected to coil 3, through which high frequency current will accordingly flow.
- the magnetic eld inside said coil is concentrated, by disc 6 and shell 8, around the refractory target 3, which is accordingly heated by the currents induced in it.
- the target 3 becomes very hot, its temperature rising to about 3600" i if sufficient energy is supplied.
- the metal carbide targets can be heated by means other than induction if desired.
- An electric induction lamp comprising ⁇ a magnetic field concentrator; a refractory induction target in operative relation therewith to be heated by the magnetic field of said concentrator, the field inthe immediate region of the concentrator deteriorating the surface thereof in said region during operation of the lamp, said target extending away from said yconcentrator for a distance greater than that over which appreciable deterioration occurs.
- An electric induction lamp comprising a magnetic field concentrator; a refractory induction target in operative relation therewith to be heated by said field, said target having a uniformly rough surface and the field in the immediate region of the lconcentrator being such as to smooth the roughene'd surface of the target in said region, said target extending away from said concentra-tor for a distance greater than that over which appreciable smoothing of said target surface occurs.
- An electric induction lamp comprising: a magnetic field concentrator including a disc having an opening therein; and a refractory induction target extending within said opening but spaced therefrom and projecting beyond the rim of the inner opening in the direction of useful light emission from the target.
- An electric induction lamp comprising: a magnetic field concentrator including a at disc having an opening therein; and a refractory induction target extending within said opening but spaced therefrom and projecting beyond the plane of the disc in the direction of light emission from the target.
- An electric induction lamp comprising: a magnetic field concentrator including a disc having an opening therein; and a refractory induction target extending within said opening but spaced therefrom and projecting beyond the rim of the inner opening in the direction of light emission from the target, whereby the apparent brightness of light emission from said target is substantially constunt over the lateral surface of said target on the side from which useful light is emitted.
- An electric ⁇ induction lamp comprising: a magnetic field concentrator including a disc having an opening therein; and a refractory induction target extending Within said opening but spaced therefrom and projecting beyond the rim of the inner opening in the direction of useful light emission from the target, a iight-transmitting envelope enclosing said concentrator and said target, and a filling of gas in said envelope.
- An electric induction lamp comprising: a magnetic field concentrator including a dat disc having an opening therein; and a refractory induction target extending within said opening but spaced therefrom and projecting beyond the plane of the disc in the direction of light emission from the target, a light-transmitting envelope enclosing said concentrator and said target, and a filling of gas in said envelope.
- An electric induction lamp comprising: a magnetic field concentrator including a disc having an opening therein; and an induction target of a refractory material selected from the group consisting of fantalum carbide, zirconium carbide, hafniurn carbide7 said target extending within said opening out spaced therefrom and projecting beyond the rim of the inner opening in the direction of useful light emission fro-m the light.
- An electric induction lamp comprising: a magnetic field concentrator including a fiat disc having an opening therein; and an induction target of a refractory material selected from the group consisting of tantalum carbide7 zirconium carbide, hafniurn carbide, said target extending within said opening but spaced therefrom and projecting beyond the plane of the disc in the direction of light emission from the target.
- An electric induction lamp comprising: a magnetic field concentrator including a disc having an opening therein; and a refractory induction target extending within said opening but spaced thenefrom and projecting beyond the rim of the inner opening in the direction of useful slight emission 'from the target, said target not extending beyond the rim of the inner opening in the direction o pposite to that of useful light emission from the target.
Landscapes
- Physical Or Chemical Processes And Apparatus (AREA)
- Vessels And Coating Films For Discharge Lamps (AREA)
- Magnetic Treatment Devices (AREA)
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
NL208599D NL208599A (fr) | 1955-07-08 | ||
US520718A US2966601A (en) | 1955-07-08 | 1955-07-08 | Induction lamp |
US520767A US2774905A (en) | 1955-07-08 | 1955-07-08 | Induction lamp |
FR1154903D FR1154903A (fr) | 1955-07-08 | 1956-07-03 | Lampe électrique à incandescence |
GB21068/56A GB806518A (en) | 1955-07-08 | 1956-07-06 | Electric induction lamp |
GB21249/56A GB806519A (en) | 1955-07-08 | 1956-07-09 | Electric induction lamp |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US520767A US2774905A (en) | 1955-07-08 | 1955-07-08 | Induction lamp |
Publications (1)
Publication Number | Publication Date |
---|---|
US2774905A true US2774905A (en) | 1956-12-18 |
Family
ID=24073974
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US520767A Expired - Lifetime US2774905A (en) | 1955-07-08 | 1955-07-08 | Induction lamp |
Country Status (4)
Country | Link |
---|---|
US (1) | US2774905A (fr) |
FR (1) | FR1154903A (fr) |
GB (2) | GB806518A (fr) |
NL (1) | NL208599A (fr) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2842698A (en) * | 1956-03-30 | 1958-07-08 | Sylvania Electric Prod | Induction lamp |
US2948826A (en) * | 1956-04-09 | 1960-08-09 | Sylvania Electric Prod | Induction lamp |
US5998914A (en) * | 1998-10-02 | 1999-12-07 | Federal-Mogul World Wide, Inc. | Electrodeless gas discharge lamp assembly and method of manufacture |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2171359A (en) * | 1936-08-03 | 1939-08-29 | Harry I Stein | Glow lamp |
-
0
- NL NL208599D patent/NL208599A/xx unknown
-
1955
- 1955-07-08 US US520767A patent/US2774905A/en not_active Expired - Lifetime
-
1956
- 1956-07-03 FR FR1154903D patent/FR1154903A/fr not_active Expired
- 1956-07-06 GB GB21068/56A patent/GB806518A/en not_active Expired
- 1956-07-09 GB GB21249/56A patent/GB806519A/en not_active Expired
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2171359A (en) * | 1936-08-03 | 1939-08-29 | Harry I Stein | Glow lamp |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2842698A (en) * | 1956-03-30 | 1958-07-08 | Sylvania Electric Prod | Induction lamp |
US2948826A (en) * | 1956-04-09 | 1960-08-09 | Sylvania Electric Prod | Induction lamp |
US5998914A (en) * | 1998-10-02 | 1999-12-07 | Federal-Mogul World Wide, Inc. | Electrodeless gas discharge lamp assembly and method of manufacture |
Also Published As
Publication number | Publication date |
---|---|
GB806518A (en) | 1958-12-23 |
NL208599A (fr) | |
GB806519A (en) | 1958-12-23 |
FR1154903A (fr) | 1958-04-18 |
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