(12) United States Patent
`Golz et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,670,763 B2
`Dec. 30, 2003
`
`US006670763B2
`
`DISPLAY LAMP WITH REFLECTOR
`HAVING IR-REFLECTIVE COATING
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`(54)
`
`(75)
`
`Inventors: Thomas M. Golz, Willoughby Hills,
`OH (US); Denis A. Lynch, South
`Euclid, OH (US)
`
`(73)
`
`Assignee: General Electric Company,
`Schenectady, NY (US)
`
`(*)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`
`(21)
`(22)
`(65)
`
`(51)
`(52)
`(58)
`
`Appl. No.: 09/858,062
`Filed:
`May 15, 2001
`
`Prior Publication Data
`
`US 2002/0171364 A1 Nov. 21, 2002
`
`Int. Cl.7 ............................................... .. H01J 13/46
`US. Cl. .............. ..
`315/56; 313/324; 362/347
`Field of Search ............................ .. 315/56, 57, 58,
`315/326, 363; 313/312, 324, 325, 113;
`362/341, 347, 296
`
`4,707,632 A 11/1987 Walsh ...................... .. 313/112
`
`4,780,799 A 10/1988 Groh . . . . . . . . . . . . . .
`
`. . . .. 362/294
`
`4,885,668 A 12/1989 Maglica et a1. . . . . .
`
`. . . .. 362/315
`
`5,177,396 A * 1/1993 Gielen et a1. . . . . . . .
`
`. . . .. 313/113
`
`5,680,000 A 10/1997 Zuk et a1. . . . . . . .
`
`. . . . . .. 313/25
`
`5,757,134 A
`
`5/1998 Williamson . . . . .
`
`. . . .. 313/613
`
`6,111,359 A * 8/2000 Work 6161. . . . . .
`. . . . . .. 313/25
`6,281,620 B1 * 8/2001 Yeh .......................... .. 313/113
`* cited by examiner
`Primary Examiner—Don Wong
`Assistant Examiner—Thuy Vinh Tran
`(74) Attorney, Agent, or Firm—Pearne & Gordon LLP
`(57)
`ABSTRACT
`
`A loW voltage display lamp is provided for use in standard
`threaded lamp sockets. The lamp has an IR-re?ective layer,
`preferably gold, coated on the convex side of the re?ector to
`re?ect infrared radiation (IR) aWay from the ballast to
`reduce the ballast’s operating temperature. The IR-re?ective
`coating is effective to re?ect IR radiation aWay from the
`lamp housing.
`20 Claims, 1 Drawing Sheet
`
`
`
`Page 1 of 5
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`PHILIPS EXHIBIT 2005
`WAC v. PHILIPS
`IPR2016-01455
`
`

`
`U.S. Patent
`
`Dec. 30, 2003
`
`US 6,670,763 B2
`
`1 [50
`
`~18
`
`F_lE.1
`PRIUR ART
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`
`
`Page 2 of 5
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`

`
`1
`DISPLAY LAMP WITH REFLECTOR
`HAVING IR-REFLECTIVE COATING
`
`2
`outer surface, and an IR-re?ective layer is disposed on the
`convex outer surface.
`
`US 6,670,763 B2
`
`BACKGROUND OF THE INVENTION
`
`This invention relates to display lamps. More particularly,
`it relates to loW voltage display lamps having a gold-coated
`re?ector to reduce heat radiation and transmittance.
`LoW voltage display lamps are knoWn in the art. LoW
`voltage display lamps for use in standard lamp sockets
`having line-voltage, such as, e.g., the Well knoWn MR16
`lamps, comprise a re?ector assembly that Works in conjunc
`tion With a voltage converter such as a solid state electronic
`ballast. The ballast is contained Within a lamp housing
`together With, disposed in close proximity to and directly
`behind the re?ector assembly. Consequently, it is important
`to minimize radiant heat from the re?ector assembly to the
`ballast in order to ensure proper operation and a long service
`life.
`Current display lamp designs employ a ?at circular heat
`shield or plate Which is disposed behind the elliptical
`re?ector of the re?ector assembly and in front of the ballast.
`This heat shield serves to protect the ballast by re?ecting
`infrared radiation (IR) generated by the ?lament and trans
`mitted through the re?ector, thereby reducing the ballast’s
`operating temperature. HoWever, a signi?cant portion of the
`re?ected IR is directed at the interior surface of the lamp
`housing. Consequently, the lamp housing, Which is already
`subject to direct IR energy from the ?lament, noW absorbs
`roughly tWice the IR compared to that radiated directly from
`the ?lament to the housing.
`The result is that the housing is more susceptible to
`melting from absorbed IR, and also that the absorbed IR Will
`be conducted as heat through the housing material to the
`ballast, thereby raising the ballast operating temperature and
`shortening its service life.
`Existing means for solving the problem of ballast heating
`include multi-layer coatings applied to the concave re?ector
`surface that are designed to re?ect IR instead of transmit it
`through the re?ector toWard the ballast.
`HoWever, such coatings are difficult to apply correctly and
`often are very expensive. Most such coatings involve apply
`ing a discrete IR-re?ective coating layer separately from and
`beneath a visible light-re?ective coating layer, thereby con
`tributing an additional coating process. It has been further
`suggested that a broad-band dichroic coating that Would
`re?ect in both the visible and IR spectra could be used.
`HoWever, such coatings Would be dif?cult to apply correctly,
`and could adversely affect the lumen ef?ciency of the lamp.
`There is a need in the art for a loW voltage display lamp
`for use in standard line-voltage electric lamp sockets, com
`prising an effective IR-re?ective coating that can be applied
`to the re?ector, Without adversely affecting the lumen ef?
`ciency or light-re?ective characteristics of the lamp. Such a
`coating Would effectively re?ect IR aWay from the ballast,
`and from the lamp housing. Such a coating Will effectively
`reduce the ballast operating temperature.
`
`15
`
`25
`
`35
`
`45
`
`55
`
`SUMMARY OF THE INVENTION
`A loW voltage display lamp is provided having a lamp
`housing, a re?ector assembly, and a solid state electronic
`ballast. The re?ector assembly has a light source therein, and
`is located Within the lamp housing, With the ballast located
`behind the re?ector assembly. The re?ector assembly also
`has a re?ector With a concave inner surface and a convex
`
`65
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is a schematic side vieW of a loW voltage display
`lamp having a ?at circular heat shield characteristic of the
`prior art.
`FIG. 2 is a partially schematic side vieW of a loW voltage
`display lamp having an IR-re?ective coating layer according
`to the present invention.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS OF THE
`INVENTION
`
`In the description that folloWs, When a preferred range,
`such as 5 to 25 (or 5—25) is given, this means preferably at
`least 5, and separately and independently, preferably not
`more than 25.
`As used herein, “MR16” means a loW voltage display
`lamp as is generally knoWn in the art, having a nominal
`diameter of tWo inches.
`With reference to FIG. 1, pictured is a characteristic or
`conventional loW voltage display lamp 10. The lamp 10
`comprises a solid state ballast 30 and a re?ector assembly
`50, both contained Within a lamp housing 40. Lamp 10
`further comprises socket coupling means (preferably
`threaded) for electrically coupling the electronic ballast 30
`to a lamp socket (not shoWn). The ballast 30 is disposed in
`the throat 42 of the housing 40 directly behind the re?ector
`assembly 50. The re?ector assembly 50 preferably com
`prises a curved re?ector 12, preferably ranging from sub
`stantially elliptical to substantially parabolic in shape, a
`?lament or light source 16, and a transparent cover plate 18.
`The re?ector 12 has a concave inner surface 13 and a convex
`outer surface 15, and is preferably substantially parabolic in
`shape. A light-re?ective coating layer (not shoWn) is coated
`onto concave surface 13. The re?ector 12 typically com
`prises a borosilicate glass material. The light source 16 is
`disposed Within the re?ector 12, facing concave surface 13.
`During operation, light source 16 of re?ector assembly 50 is
`electrically coupled to ballast 30 via metal pins, Wires, or
`some other knoWn means (not shoWn). The re?ector 12
`terminates in a rim 11 forming the entire perimeter of the
`open end of the re?ector 12.
`The lamp 10 may optionally comprise a nose or boss 14
`formed integrally With and extending outWardly from the
`outer surface of the base 17 of the re?ector 12. The boss 14
`preferably has a rectangular cross-section, though cross
`sections of other shapes are possible and can be used.
`Preferably, the re?ector 12 and the boss 14 are integrally
`formed from glass, preferably borosilicate glass. The lamp
`of FIG. 2 is of this same general construction.
`With reference to FIG. 1, a conventional lamp 10 com
`prises a conventional or knoWn heat shield 20. The heat
`shield 20 is positioned betWeen base 17 of re?ector 12 and
`ballast 30 in order that the heat shield re?ects IR transmitted
`through the re?ector 12 aWay from the ballast 30. As can be
`seen in FIG. 1, a heat shield 20 as described above re?ects
`incident radiation 2, and directs it as re?ected radiation 4
`toWard a point 8 along the interior surface of the lamp
`housing 40. In addition to the re?ected radiation 4, point 8
`also receives direct radiation 6 from light source 16. Hence
`the re?ected radiation 4 effectively doubles or increases the
`absorbed IR load at point 8, thereby signi?cantly increasing
`the localiZed housing temperature around point 8. It Will be
`
`
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`Page 3 of 5
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`

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`US 6,670,763 B2
`
`3
`understood that such double or enhanced absorption is not a
`discretiZed effect around a single point 8 as portrayed in
`FIG. 1. Discrete point 8 is pictured merely for illustration.
`This double absorption phenomenon occurs along the inte
`rior surface of housing 40, thereby signi?cantly increasing
`its temperature.
`Increased housing temperature increases the danger of
`housing meltdown, requiring that housing materials having
`high softening or melting points must be used. In addition,
`absorbed IR is conducted as heat through the housing back
`to the throat portion 42 Which encloses the ballast 30. The
`conducted energy is then transferred to the ballast via
`conduction through the physical pathWays betWeen the
`ballast 30 and the housing 40, and via radiation from the
`housing 40 to the ballast 30. Additionally, thermal currents
`transfer thermal energy to the ballast via convection as
`knoWn in the art. Thermal energy transferred to the ballast
`30 via the above mechanisms raises the ballast’s operating
`temperature thereby reducing its service life.
`NoW referring to FIG. 2, convex surface 15 of re?ector 12
`is coated With an IR-re?ective layer 35 effective to re?ect
`transmitted IR back through re?ector 12 to exit lamp 10
`through clear cover 18. IR-re?ective layer 35 is made from
`a material capable of Withstanding operating temperatures in
`excess of 200, preferably 250, preferably 300, preferably
`350, preferably 400, ° C., Without tarnishing, becoming
`oxidiZed, or otherWise being affected in a manner adverse to
`its IR-re?ectivity. IR-re?ective layer 35 is or comprises
`preferably a gold, less preferably silver, less preferably
`aluminum, less preferably nickel, less preferably titanium,
`less preferably chromium layer, less preferably some other
`metal layer, less preferably a metal alloy layer, less prefer
`ably some other material knoWn in the art. Preferably, the
`re?ective layer 35 is 50—200, preferably 60—180, preferably
`75—160, preferably 90—140, preferably 100—130, preferably
`110—125, preferably about 120, nm thick.
`Gold is most preferred because it is highly impervious to
`adverse temperature effects, and does not tarnish, melt,
`oxidiZe, or otherWise deform under operating temperatures
`up to and in excess of 400° C. In addition, gold exhibits a
`substantially ?at re?ectivity pro?le throughout the relevant
`IR spectrum (about 0.7—4.0p Wavelength), at about 99%
`re?ectivity. (The glass in re?ector 12 is essentially fully
`absorbent of IR radiation beyond 4.0 p, transmitting none
`through to the re?ective layer 35). When gold is used in
`re?ective layer 35, a base layer 36 is preferably deposited on
`convex surface 15 betWeen convex surface 15 and re?ective
`layer 35, preferably by vacuum vapor deposition. Base layer
`36 is as thin as possible to effectively serve its adhesive
`purpose. Base layer 36 is preferably less than 20, more
`preferably 16, more preferably 12, more preferably 10, more
`preferably 8, more preferably 6, more preferably 5, more
`preferably 4, nm thick. Base layer 36 is most preferably pure
`titanium or titanium, less preferably chromium, less prefer
`ably any other material (preferably metallic) having good
`adhesion to both surface 15 and the gold re?ective layer.
`It should be noted that gold can be deposited directly onto
`a glass surface. HoWever gold exhibits very poor adhesion
`to glass, and thus immediately ?akes off upon even the
`slightest contact. Nevertheless, because the gold layer in the
`?nished lamp 10 is totally enclosed, it is possible to provide
`a gold re?ective layer according to the present invention
`Without a base layer 36, so long as the lamp is manufactured
`in such a Way as to ensure no contact With the gold-deposited
`convex surface of re?ector 12 once the gold has been
`deposited thereon. It is probable that such a manufacturing
`process Would introduce excessive cost and Would be quite
`
`10
`
`15
`
`20
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`25
`
`30
`
`35
`
`40
`
`45
`
`50
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`55
`
`60
`
`65
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`4
`cumbersome; accordingly it is preferable to provide the base
`layer 36 When a gold layer is used.
`In a less preferred embodiment, use of some materials
`other than gold in re?ective layer 35, for example silver or
`aluminum, Will obviate the need for base layer 36 because
`such materials are suf?ciently adherent to glass (borosilicate
`glass) to effectively adhere directly to convex surface 15 of
`re?ector 12. Though silver has a substantially uniform
`re?ectivity pro?le in the IR-spectrum, and similarly to gold
`is further about 99% re?ective of IR radiation, silver suffers
`from the limitation that it tarnishes easily via oxidation at
`high temperature. Thus, When silver is used in re?ective
`layer 35, the silver layer should be suf?ciently thick such
`that tarnish cannot penetrate through the silver layer to the
`silver surface immediately adjacent convex surface 15.
`Alternatively, When silver is used in re?ective layer 35, a
`protective coating layer, e.g. silica, can be deposited over the
`silver re?ective layer to prevent silver tarnishing or oxida
`tion. Providing such a thick silver layer Will yield a silver
`re?ective surface adjacent convex surface 15 that is sub
`stantially unaffected by tarnish from the opposite side of the
`silver layer. Thus re?ective layer 35 may be disposed on
`convex outer surface 15 With or Without the presence of base
`layer 36.
`In addition to preventing direct IR radiation to ballast 30,
`and to preventing re?ected IR from being directed toWard
`housing 40 (see reference numeral 4 in FIG. 1), the re?ective
`layer 35 also substantially prevents direct radiation to hous
`ing 40 from light source 16 (see reference numeral 6 in FIG.
`1). As can be seen in FIG. 2, incident radiation 2 is directed
`forWard through re?ector 12 as re?ected radiation 9, to exit
`the lamp. The transparent cover 18 transmits nearly 100% of
`the re?ected IR, absorbing almost none. Consequently, the
`re?ected IR substantially escapes the lamp, and therefore is
`not absorbed by the lamp housing 40 to raise its temperature.
`Optionally, a heat shield 20 can be disposed betWeen re?ec
`tor 12 and ballast 30 as shoWn in FIG. 1.
`It is believed that invented re?ective layer 35 Will
`decrease the ballast temperature by 5—10° C. Current MR16
`display lamps operate in the range of 20—71 Watts
`The
`higher the Wattage, the greater the light output of the lamp.
`Ballasts used in conjunction, and in close proximity, With 20
`W MR16 lamps operate near threshold temperature due to
`the transfer of heat from the light source 16 to the ballast 30
`via the various mechanisms described above. The invented
`re?ective layer 35 alloWs a ballast to be incorporated into a
`housing in close proximity With a higher Wattage MR16
`lamp, (eg at least or about 35 W, 45 W, 55 W, 65 W, or 71
`W), and to operate suf?ciently beloW threshold temperature
`to ensure long life, preferably rated at more than 3000,
`preferably 3500, preferably 4000, preferably 4500, prefer
`ably 5000, hours.
`Though the above-described preferred embodiment has
`been described With regard to an MR16 lamp, it Will be
`understood that the invention could be applied to display
`lamps of different shapes and siZes Without departing from
`the scope of the invention. For example, the invented
`re?ective layer 35 can be utiliZed in MR8, MR11, MR20,
`MR30, MR38, PAR16, PAR20, PAR30, and PAR38 display
`lamps, as Well as any other re?ector lamp knoWn in the art,
`and Would be similarly provided and comprised as described
`above.
`While the invention has been described With reference to
`a preferred embodiment, it Will be understood by those
`skilled in the art that various changes may be made and
`equivalents may be substituted for elements thereof Without
`
`
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`Page 4 of 5
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`

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`US 6,670,763 B2
`
`5
`departing from the scope of the invention. In addition, many
`modi?cations may be made to adapt a particular situation or
`material to the teachings of the invention Without departing
`from the essential scope thereof. Therefore, it is intended
`that the invention not be limited to the particular embodi
`ment disclosed as the best mode contemplated for carrying
`out this invention, but that the invention Will include all
`embodiments falling Within the scope of the appended
`claims.
`What is claimed is:
`1. AloW voltage display lamp comprising a lamp housing,
`a re?ector assembly, and a solid state electronic ballast, said
`re?ector assembly comprising a light source, said re?ector
`assembly being disposed Within said housing, said ballast
`being disposed behind said re?ector assembly, said re?ector
`assembly further comprising a re?ector having a concave
`inner surface and a conveX outer surface, and an
`IR-re?ective layer disposed on said conveX outer surface.
`2. A lamp according to claim 1, said lamp further com
`prising a base layer disposed on said conveX outer surface
`betWeen said outer surface and said IR-re?ective layer.
`3. Alamp according to claim 2, Wherein said base layer is
`titanium.
`4. Alamp according to claim 2, Wherein said base layer is
`chromium.
`5. Alamp according to claim 2, Wherein said base layer is
`less than 20 nm thick.
`6. A lamp according to claim 2, Wherein said IR-re?ective
`layer is gold.
`7. A lamp according to claim 1, Wherein said IR-re?ective
`layer is gold.
`8. A lamp according to claim 1, Wherein said IR-re?ective
`layer is silver.
`
`10
`
`20
`
`25
`
`30
`
`6
`9. A lamp according to claim 8, further comprising a
`protective layer deposited over said silver IR-re?ective
`layer.
`10. A lamp according to claim 9, said protective layer
`being silica.
`11. A lamp according to claim 1, Wherein said
`IR-re?ective layer is selected from the group consisting of
`titanium, chromium, nickel and aluminum.
`12. A lamp according to claim 1, Wherein said
`IR-re?ective layer is 50—200 nm thick.
`13. Alamp according to claim 1, further comprising a heat
`shield disposed betWeen said re?ector and said ballast.
`14. Alamp according to claim 1, said lamp having a rated
`life longer than 3000 hours.
`15. Alamp according to claim 1, further comprising a heat
`shield disposed betWeen said re?ector assembly and said
`ballast.
`16. A lamp according to claim 1, Wherein said re?ector is
`substantially parabolic in shape.
`17. A lamp according to claim 1, Wherein said re?ector is
`substantially elliptical in shape.
`18. A lamp according to claim 1, said re?ector comprising
`a glass material.
`19. A lamp according to claim 1, said re?ector comprising
`borosilicate glass.
`20. A lamp according to claim 1, said re?ector comprising
`a glass material, said IR-re?ective layer that is disposed on
`said conveX outer surface of said re?ector being a metallic
`layer.
`
`
`
`Page 5 of 5