CA2062017A1 - Automotive arc headlamp with reduced uv emission - Google Patents
Automotive arc headlamp with reduced uv emissionInfo
- Publication number
- CA2062017A1 CA2062017A1 CA 2062017 CA2062017A CA2062017A1 CA 2062017 A1 CA2062017 A1 CA 2062017A1 CA 2062017 CA2062017 CA 2062017 CA 2062017 A CA2062017 A CA 2062017A CA 2062017 A1 CA2062017 A1 CA 2062017A1
- Authority
- CA
- Canada
- Prior art keywords
- lamp
- assembly
- reflector
- radiation
- lens
- 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.)
- Abandoned
Links
- 238000000576 coating method Methods 0.000 claims abstract description 52
- 230000005855 radiation Effects 0.000 claims abstract description 46
- 239000011248 coating agent Substances 0.000 claims abstract description 41
- 238000010891 electric arc Methods 0.000 claims abstract description 17
- 239000004033 plastic Substances 0.000 claims description 24
- 229920003023 plastic Polymers 0.000 claims description 24
- 229910001507 metal halide Inorganic materials 0.000 claims description 4
- 150000005309 metal halides Chemical class 0.000 claims description 4
- 230000003287 optical effect Effects 0.000 claims description 4
- 239000004417 polycarbonate Substances 0.000 abstract description 7
- 229920000515 polycarbonate Polymers 0.000 abstract description 7
- 230000015556 catabolic process Effects 0.000 abstract description 4
- 238000006731 degradation reaction Methods 0.000 abstract description 4
- 230000000712 assembly Effects 0.000 abstract description 2
- 238000000429 assembly Methods 0.000 abstract description 2
- 229920006238 degradable plastic Polymers 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 9
- 239000000126 substance Substances 0.000 description 6
- 239000006096 absorbing agent Substances 0.000 description 5
- 229920001296 polysiloxane Polymers 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 230000002745 absorbent Effects 0.000 description 3
- 239000002250 absorbent Substances 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 238000005299 abrasion Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 241000905957 Channa melasoma Species 0.000 description 1
- JOYRKODLDBILNP-UHFFFAOYSA-N Ethyl urethane Chemical compound CCOC(N)=O JOYRKODLDBILNP-UHFFFAOYSA-N 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- 239000011358 absorbing material Substances 0.000 description 1
- NIXOWILDQLNWCW-UHFFFAOYSA-N acrylic acid group Chemical group C(C=C)(=O)O NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 230000009982 effect on human Effects 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 238000005286 illumination Methods 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 239000003973 paint Substances 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 239000002966 varnish Substances 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F21—LIGHTING
- F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
- F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
- F21V9/06—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters for filtering out ultraviolet radiation
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Non-Portable Lighting Devices Or Systems Thereof (AREA)
- Discharge Lamps And Accessories Thereof (AREA)
- Vessels And Coating Films For Discharge Lamps (AREA)
Abstract
AUTOMOTIVE ARC HEADLAMP WITH REDUCED UV EMISSION
ABSTRACT OF THE DISCLOSURE
Automotive headlamp assemblies employing an arc discharge lamp which emits both visible and UV
radiation as the light source and which have a UV
degradable plastic lens, such as polycarbonate, have a UV absorbing coating disposed on both the reflecting surface and interior surface of the lens to protect the lens from UV degradation.
ABSTRACT OF THE DISCLOSURE
Automotive headlamp assemblies employing an arc discharge lamp which emits both visible and UV
radiation as the light source and which have a UV
degradable plastic lens, such as polycarbonate, have a UV absorbing coating disposed on both the reflecting surface and interior surface of the lens to protect the lens from UV degradation.
Description
2 ~
AUTONOTIVE .~RC HEADL~MP WITH REDUCED W EMISSION
BACKGROUND OF THE INVENTION
Field of_the Invention This inven ion relates to an automotive arc discharge headlamp having reduced ultraviolet (W) emission. ~ore particularly, this invention relates to an automotive headlamp comprising a forward projecting reflector with a light transmissive lens mounted on the forward end and enclosing an electric arc discharge lamp within as a light source, wherein the reflecting surface of the reflector is coated with a W absorbing coating.
Background Of The Disclosure There is much interest in the automobile industry in using arc lamps also known as arc discharge lamps as the light source for automotive headlamps.
Tungsten-halogen lamps are presently used, but arc lamps have potentially longer life, higher light output and much higher source brightness. The small size of the arc lamps and concomitant reflector and lens assembly provide automotive manu~acturers a greater leeway in innovative front end automotive design. Arc discharge lamps useful for automotive applications are .
2 ~
-2~ LD 9990 basically miniature metal halide arc discharge lamps.
One of the disadvantages associated with such lamps for automotive use is that they emit a siynificant amount of W radiation. Emission o~ W radiation by automotive headlamps is undesirable because of its adverse effect on human eyes and skin. Further, miniature automotive headlamps employing arc discharge lamps are often plastic and have plastic lenses.
Plastic lenses are easier to fabricate than glass into more complex shapes for automotive styling. Plastic is more flexible than glass and can possess greater impact resistance. Polycarbonate is the plastic of choice for such lenses because of its clear, visi~le light transmissive properties along with excellent impact and abrasion resistance. Unfortunately, polycarbonate and other plastics turn yellow or brown and/or become hazy when exposed to W radiation.
Accordingly, a need exists for automotive arc headlamps having reduced UV emission, particularly when the headlamps employ plastic reflectors and plastic lenses.
SUMMARY OF THE INVENTION
The present invention relates to a reflector and lamp assembly employing an arc discharge lamp which ~5 emits W radiation as the light source and which has a W absorbing coating on the reflecting surface of the reflector to reduce the amount of W radiation projected forward of the reflector. Such lamp and reflector combinations have been made without the presence of a lens on the open, visible ligh~
projecting end of the re~lector, wherein less ~han 10%
of the W radiation emitted by the lamp is projected forward of the reflector due to absorption of the W by ~fi2~7 -3- LD gsso the coating on the re~lecting surface. In one em~odiment, the lamp will employ a light transmissive lens made of a material which is degraded by UV
radiation. In such an embodiment, it is preferred that the interior surface of the lens also has disposed on it a coating which absorbs W radiation. Thus, another embodiment o the present invention relates to an automotive headlamp assembly comprising an arc discharge lamp which emits both W and visible light radiation enclosed within a forward projecting light reflector which has a light transmissive lens at one end that is degraded by W radiation, with a W
absorbing and visible light transmissive coating on the interior reflecting sur~ace of the reflector and on the interior surface of the lens.
By W radiation is meant radiation having a wavelength generally below about 400 nm. W radiation having a wavelenqth of about 320 nm or less is known to have a detrimental effect on human eyes while that having a wavelength of about 340 nm or less will degrade polycarbonate plastic causing it to turn yellow and/or become hazy, depending on the wavelength.
Accordingly, the W absorbing coating should be selected so as to absorb W radiation having a wavelength equal to or below about 340 nm and at the same time be substantially nonabsorbent and transparent to visible light radiation. The coating must also be somewhat heat resistant due to its presence inside the interior cavity of a sealed automotive headlamp reflector wherein operation of the arc discharge lamp can heat the inside of the reflector to a temperature of 150C and more. Proprietary coatings commercially available on the market comprising one or more silicone resins in which is dissolved or dispersed a W
absorbing material have been found satis~actory for use ~fi%~
AUTONOTIVE .~RC HEADL~MP WITH REDUCED W EMISSION
BACKGROUND OF THE INVENTION
Field of_the Invention This inven ion relates to an automotive arc discharge headlamp having reduced ultraviolet (W) emission. ~ore particularly, this invention relates to an automotive headlamp comprising a forward projecting reflector with a light transmissive lens mounted on the forward end and enclosing an electric arc discharge lamp within as a light source, wherein the reflecting surface of the reflector is coated with a W absorbing coating.
Background Of The Disclosure There is much interest in the automobile industry in using arc lamps also known as arc discharge lamps as the light source for automotive headlamps.
Tungsten-halogen lamps are presently used, but arc lamps have potentially longer life, higher light output and much higher source brightness. The small size of the arc lamps and concomitant reflector and lens assembly provide automotive manu~acturers a greater leeway in innovative front end automotive design. Arc discharge lamps useful for automotive applications are .
2 ~
-2~ LD 9990 basically miniature metal halide arc discharge lamps.
One of the disadvantages associated with such lamps for automotive use is that they emit a siynificant amount of W radiation. Emission o~ W radiation by automotive headlamps is undesirable because of its adverse effect on human eyes and skin. Further, miniature automotive headlamps employing arc discharge lamps are often plastic and have plastic lenses.
Plastic lenses are easier to fabricate than glass into more complex shapes for automotive styling. Plastic is more flexible than glass and can possess greater impact resistance. Polycarbonate is the plastic of choice for such lenses because of its clear, visi~le light transmissive properties along with excellent impact and abrasion resistance. Unfortunately, polycarbonate and other plastics turn yellow or brown and/or become hazy when exposed to W radiation.
Accordingly, a need exists for automotive arc headlamps having reduced UV emission, particularly when the headlamps employ plastic reflectors and plastic lenses.
SUMMARY OF THE INVENTION
The present invention relates to a reflector and lamp assembly employing an arc discharge lamp which ~5 emits W radiation as the light source and which has a W absorbing coating on the reflecting surface of the reflector to reduce the amount of W radiation projected forward of the reflector. Such lamp and reflector combinations have been made without the presence of a lens on the open, visible ligh~
projecting end of the re~lector, wherein less ~han 10%
of the W radiation emitted by the lamp is projected forward of the reflector due to absorption of the W by ~fi2~7 -3- LD gsso the coating on the re~lecting surface. In one em~odiment, the lamp will employ a light transmissive lens made of a material which is degraded by UV
radiation. In such an embodiment, it is preferred that the interior surface of the lens also has disposed on it a coating which absorbs W radiation. Thus, another embodiment o the present invention relates to an automotive headlamp assembly comprising an arc discharge lamp which emits both W and visible light radiation enclosed within a forward projecting light reflector which has a light transmissive lens at one end that is degraded by W radiation, with a W
absorbing and visible light transmissive coating on the interior reflecting sur~ace of the reflector and on the interior surface of the lens.
By W radiation is meant radiation having a wavelength generally below about 400 nm. W radiation having a wavelenqth of about 320 nm or less is known to have a detrimental effect on human eyes while that having a wavelength of about 340 nm or less will degrade polycarbonate plastic causing it to turn yellow and/or become hazy, depending on the wavelength.
Accordingly, the W absorbing coating should be selected so as to absorb W radiation having a wavelength equal to or below about 340 nm and at the same time be substantially nonabsorbent and transparent to visible light radiation. The coating must also be somewhat heat resistant due to its presence inside the interior cavity of a sealed automotive headlamp reflector wherein operation of the arc discharge lamp can heat the inside of the reflector to a temperature of 150C and more. Proprietary coatings commercially available on the market comprising one or more silicone resins in which is dissolved or dispersed a W
absorbing material have been found satis~actory for use ~fi%~
with the present invention.
DETAILED DESCRIPTION OF THE D~WINGS
Figure 1 schematically illus~rates a plastic lens, reflector, and lamp ass~mbly u~eful in the practice of the present invention with the reflecting surface coated with a W absorbing coating.
Figure 2 is a graph illustrating the W attenuation factor as a function of wavelength using a reflector similar to that in Figure 1 containing a W absorbing coating on the interior reflecting surface, but without a lens.
Figure 3 is a graph illustrating the W spectral output of a miniature arc discharge lamp of the type illustrated in Figure 1.
DETAILED DESCRIPTION
Turning to Figure 1 there is shown automotive headlamp reflector assembly 10 comprising all plastic molded reflector 12 consisting of a parabolic or elliptical reflecting portion 14, open at its forward projecting end 18 and terminating at its rear end in an integrally molded base portion 16. The interior sur~ace of reflector 12 is coated with a thin, light reflecting, shiny coating of aluminum 22 over which is disposed W absorbing coating 24. Coating 24 is clear ~5 and is substantially transparent and non-absorbing to radiation in the visible light region~ but absorbs radiation in the W region (i.e., ~ 400 nm). The forward end 18 of reflector 12 is hermetically sealed with plastic lens 26 which is tran~parent to visible light radiation. In an embodiment where lens 26 is 2~2~7 made of a plastic which is degraded by W radiation, such as a polycarbonate which has excellen~ light transmission, strength, impact and abrasion resistance and which is often the plastic of choic~ for such applications, the interior surface 42 of the lens is also coated with UV absorbing coating 24 to insure that little or none of the W radiation emitted by lamp 28 reaches the plastic lens. It should be noted that if lens 26 is glass, then no coating would be necessary since glass is a natural absorber of W radiation and its transparency to visible light radiation is unaffected by exposure to W radiation. Miniature arc discharge lamp 28 is enclosed within assembly 10 with its optical center approximately coinciding with the focal point of reflector 12. Lamp 2~ comprises a synthetic quartz envelope 30 enclosing within electrodes 32 hermetically sealed within arc rhamber 34 as is well known to those skilled in the art. Arc chamber 34 also contains, as is known to those skilled in the art, a small amount of mercury along with one more more metal halides and an inert starting gas, such as xenon. Lamp 28 is connected by means of mount wires 38 and 39 to base portion 16 (by means not shown) and thence to terminal pins 40 for connection to a source of electric current. In automotive applications, a metal shield (not shown) will be employed in front of the forward end of the lamp to insure that all of the light projected forward of the reflector is reflected from reflecting surface 22. Such metal light shields and their uses in association with such lamps are known to those skilled in the art and examples may be found, ~or example, in U.S. Patents 4,795,939 and 4,754,373.
W absorbing coatings for protecting W degradable plastics from W radiation are co~mercially available and may be obtained from coating manufacturers and -6- LD 99~0 suppliers such as the Silicone Division (GE Silicones) of GE Plastics in Waterford, N.Y., Dow Corning, DuPont, Sherwin Williams, Bee Chemical Company and the like.
Such ccatings are clear and absorb little or no light in the visible region of the spactrum (i.e., 400 750 nm). These coating materials contain a W absorber for absorbing radiation in the W portion of the spectrum (i.e., < 400 nm). Heat resistant coatings are preferred for use in the present invention. Xeat resistant coatings and also heat resistant W a~sorbers are generally based on silicone containing compounds or at least contain such compounds. Illustrative, but non-limiting examples of both coatings and W absorbers containing silicone compounds and suitable for use in the present invention are disclosed and claim~d, for example, in U.S. Patent Nos. 4,374,674: 4,278,804;
3,986,997; 4,177,315 and 4,644,077, the disclosures of which are incorporated herein by reference.
Although the examples and disclosure of this invention have been directed mostly to automotive types of applications, the invention is not meant to be so restricted. Thus, the invention may also be used for spotlight and general illumination types of lighting applications, with elliptical or parabolic shaped reflectors, with or without a plastic lens, etc.
~X~MPL~S
In one experiment, reflector and lamp assemblies similar to those illustrated in Figure 1 and described above, (with the exception that the for~ard, light projecting end of the reflector was open and not covered with a lens) were assembled. The re~lector was parabolic having a 7/8 inch ~ocal length and arc lamp 28 was a miniature, 30 watt lamp intended for 2 ~ 1 7 -7- LD 999o automotive applications. The aluminum reflecting surface 22 was coated by the manufactursr with an 8 micron thick coating of a clear, essentially non-UV
absorbent coating material designed to prevent corrosion and dulling of the highly light reflective aluminum coating. This coating material is a proprietary acrylic composition, ET4, obtained from the Red Spot Paint & Varnish Company. Some of the reflectors were th~n top-coated with two different commercially available coating materials used to protect plastics, particularly polycarbonate plastics, from W degradation. These two coating materials, LTC5000 and LS123, were obtained from Bee Chemical Company and are believed to be organic resins containing a W absorber. One of these is based on a urethane/melamine organic rssin, and the other is of unknown composition. The recommended thickness for these coatings are 1.6 mils and 0.20 mils, respectively. The 30 watt miniature metal halide arc lamps were assembled into the reflectors with the arc center at the focal point, and the arc lamp was then energized. An ultraviolet spectral energy distribution was measured in the projected beam, 50 cm from the front of the reflector, with an optronic Laboratories, Inc., Model 742, Spectroradiometer. The results of the measurements are illustrated in Figure 2 as plots of attenuation factor as a function of wavelength. Figure 3 illustrates the W spectrum of the lamp projected forward of the reflector with no W absorbing coating.
Turning to Figure 2, the attenuation factor at each wavelength was computed by taking the ratio of the msasurements for reflectors with organic W absorbent coatings to those without W absorbent coatings. In another experiment, W transparent flat quartæ plates were coated with either ET4, or a clear coating 2 ~ 7 material, AS4000, obtained from GE in Waterford, New York, based on silicones, which contained a UV
absorber. The thicknes~ of this coating was about 0.22 mils. Transmission versus wavelength ~or the sample plates was measured. Also plotted in Figure 2 is the square of the measurements at each wavelength to simulate the attenuation charac~eristics of these two materials on a reflector surface, where radiation from the arc source makss two passes through the coating.
The top curve, curve A, represents a reflector having only the aluminum protective coating ET4, which exhibited little attenuation or absorption of W
radiation above 300 nm. Curves B, C and D represent reflectors having the GE ~S4000, Bee Chemical LS123 and ~ee Chemical LTC5000 W absorbing coatings, respectively, over an ET4 coated reflector. It is immediately obvious from curve B that the GE coating AS4000 absorbed essentially all of the W radiation below about 350 nm, whereas one of the Bee Chemical coatings LS123 repr~sented by curve C, absor~Pd almost all of the W radiation below about 360 nm, and the other Bee Chemical coating LTC5000 represented by curve D, absorbed almost all of the W radiation below about 380 nm. This indicates that a W absorbing coating ~5 system, completely satisfactory for initial performance, can be achieved using any of these three coatings on the reflecting surface and/or on a polycarbonate lens to avoid degradation of the lens.
However, life tests revealed that the LTC5000 coating turned yellow and started to peel off the reflector after 1000 hours of lamp operation. No objectionable degradation of the other two materials was observed in over 2000 hours of life testing.
DETAILED DESCRIPTION OF THE D~WINGS
Figure 1 schematically illus~rates a plastic lens, reflector, and lamp ass~mbly u~eful in the practice of the present invention with the reflecting surface coated with a W absorbing coating.
Figure 2 is a graph illustrating the W attenuation factor as a function of wavelength using a reflector similar to that in Figure 1 containing a W absorbing coating on the interior reflecting surface, but without a lens.
Figure 3 is a graph illustrating the W spectral output of a miniature arc discharge lamp of the type illustrated in Figure 1.
DETAILED DESCRIPTION
Turning to Figure 1 there is shown automotive headlamp reflector assembly 10 comprising all plastic molded reflector 12 consisting of a parabolic or elliptical reflecting portion 14, open at its forward projecting end 18 and terminating at its rear end in an integrally molded base portion 16. The interior sur~ace of reflector 12 is coated with a thin, light reflecting, shiny coating of aluminum 22 over which is disposed W absorbing coating 24. Coating 24 is clear ~5 and is substantially transparent and non-absorbing to radiation in the visible light region~ but absorbs radiation in the W region (i.e., ~ 400 nm). The forward end 18 of reflector 12 is hermetically sealed with plastic lens 26 which is tran~parent to visible light radiation. In an embodiment where lens 26 is 2~2~7 made of a plastic which is degraded by W radiation, such as a polycarbonate which has excellen~ light transmission, strength, impact and abrasion resistance and which is often the plastic of choic~ for such applications, the interior surface 42 of the lens is also coated with UV absorbing coating 24 to insure that little or none of the W radiation emitted by lamp 28 reaches the plastic lens. It should be noted that if lens 26 is glass, then no coating would be necessary since glass is a natural absorber of W radiation and its transparency to visible light radiation is unaffected by exposure to W radiation. Miniature arc discharge lamp 28 is enclosed within assembly 10 with its optical center approximately coinciding with the focal point of reflector 12. Lamp 2~ comprises a synthetic quartz envelope 30 enclosing within electrodes 32 hermetically sealed within arc rhamber 34 as is well known to those skilled in the art. Arc chamber 34 also contains, as is known to those skilled in the art, a small amount of mercury along with one more more metal halides and an inert starting gas, such as xenon. Lamp 28 is connected by means of mount wires 38 and 39 to base portion 16 (by means not shown) and thence to terminal pins 40 for connection to a source of electric current. In automotive applications, a metal shield (not shown) will be employed in front of the forward end of the lamp to insure that all of the light projected forward of the reflector is reflected from reflecting surface 22. Such metal light shields and their uses in association with such lamps are known to those skilled in the art and examples may be found, ~or example, in U.S. Patents 4,795,939 and 4,754,373.
W absorbing coatings for protecting W degradable plastics from W radiation are co~mercially available and may be obtained from coating manufacturers and -6- LD 99~0 suppliers such as the Silicone Division (GE Silicones) of GE Plastics in Waterford, N.Y., Dow Corning, DuPont, Sherwin Williams, Bee Chemical Company and the like.
Such ccatings are clear and absorb little or no light in the visible region of the spactrum (i.e., 400 750 nm). These coating materials contain a W absorber for absorbing radiation in the W portion of the spectrum (i.e., < 400 nm). Heat resistant coatings are preferred for use in the present invention. Xeat resistant coatings and also heat resistant W a~sorbers are generally based on silicone containing compounds or at least contain such compounds. Illustrative, but non-limiting examples of both coatings and W absorbers containing silicone compounds and suitable for use in the present invention are disclosed and claim~d, for example, in U.S. Patent Nos. 4,374,674: 4,278,804;
3,986,997; 4,177,315 and 4,644,077, the disclosures of which are incorporated herein by reference.
Although the examples and disclosure of this invention have been directed mostly to automotive types of applications, the invention is not meant to be so restricted. Thus, the invention may also be used for spotlight and general illumination types of lighting applications, with elliptical or parabolic shaped reflectors, with or without a plastic lens, etc.
~X~MPL~S
In one experiment, reflector and lamp assemblies similar to those illustrated in Figure 1 and described above, (with the exception that the for~ard, light projecting end of the reflector was open and not covered with a lens) were assembled. The re~lector was parabolic having a 7/8 inch ~ocal length and arc lamp 28 was a miniature, 30 watt lamp intended for 2 ~ 1 7 -7- LD 999o automotive applications. The aluminum reflecting surface 22 was coated by the manufactursr with an 8 micron thick coating of a clear, essentially non-UV
absorbent coating material designed to prevent corrosion and dulling of the highly light reflective aluminum coating. This coating material is a proprietary acrylic composition, ET4, obtained from the Red Spot Paint & Varnish Company. Some of the reflectors were th~n top-coated with two different commercially available coating materials used to protect plastics, particularly polycarbonate plastics, from W degradation. These two coating materials, LTC5000 and LS123, were obtained from Bee Chemical Company and are believed to be organic resins containing a W absorber. One of these is based on a urethane/melamine organic rssin, and the other is of unknown composition. The recommended thickness for these coatings are 1.6 mils and 0.20 mils, respectively. The 30 watt miniature metal halide arc lamps were assembled into the reflectors with the arc center at the focal point, and the arc lamp was then energized. An ultraviolet spectral energy distribution was measured in the projected beam, 50 cm from the front of the reflector, with an optronic Laboratories, Inc., Model 742, Spectroradiometer. The results of the measurements are illustrated in Figure 2 as plots of attenuation factor as a function of wavelength. Figure 3 illustrates the W spectrum of the lamp projected forward of the reflector with no W absorbing coating.
Turning to Figure 2, the attenuation factor at each wavelength was computed by taking the ratio of the msasurements for reflectors with organic W absorbent coatings to those without W absorbent coatings. In another experiment, W transparent flat quartæ plates were coated with either ET4, or a clear coating 2 ~ 7 material, AS4000, obtained from GE in Waterford, New York, based on silicones, which contained a UV
absorber. The thicknes~ of this coating was about 0.22 mils. Transmission versus wavelength ~or the sample plates was measured. Also plotted in Figure 2 is the square of the measurements at each wavelength to simulate the attenuation charac~eristics of these two materials on a reflector surface, where radiation from the arc source makss two passes through the coating.
The top curve, curve A, represents a reflector having only the aluminum protective coating ET4, which exhibited little attenuation or absorption of W
radiation above 300 nm. Curves B, C and D represent reflectors having the GE ~S4000, Bee Chemical LS123 and ~ee Chemical LTC5000 W absorbing coatings, respectively, over an ET4 coated reflector. It is immediately obvious from curve B that the GE coating AS4000 absorbed essentially all of the W radiation below about 350 nm, whereas one of the Bee Chemical coatings LS123 repr~sented by curve C, absor~Pd almost all of the W radiation below about 360 nm, and the other Bee Chemical coating LTC5000 represented by curve D, absorbed almost all of the W radiation below about 380 nm. This indicates that a W absorbing coating ~5 system, completely satisfactory for initial performance, can be achieved using any of these three coatings on the reflecting surface and/or on a polycarbonate lens to avoid degradation of the lens.
However, life tests revealed that the LTC5000 coating turned yellow and started to peel off the reflector after 1000 hours of lamp operation. No objectionable degradation of the other two materials was observed in over 2000 hours of life testing.
Claims (21)
1. A lamp and reflector assembly wherein said lamp emits both UV and visible radiation and is mounted within said reflector, said reflector having an internal reflecting surface for reflecting said radiation forward of said reflector and having a UV
absorbing coating disposed on said reflecting surface for absorbing UV radiation emitted by said lamp.
absorbing coating disposed on said reflecting surface for absorbing UV radiation emitted by said lamp.
2. The assembly of claim 1 wherein said UV
absorbing coating is substantially nonabsorbent and transparent to visible light radiation.
absorbing coating is substantially nonabsorbent and transparent to visible light radiation.
3. The assembly of claim 2 wherein the optical center of said lamp is located at about the focal point of said reflector.
4. The assembly of claim 3 wherein said lamp is an arc discharge lamp.
5. The assembly of claim 4 wherein said lamp is a miniature arc discharge lamp.
6. A lamp, reflector and plastic lens assembly wherein said lamp emits both UV and visible radiation and is mounted within said reflector, said reflector having a forward light projecting end and an internal reflecting surface for reflecting UV and visible light radiation, said reflecting surface being coated with a UV absorbing coating for absorbing UV radiation emitted by said lamp, and said lens being mounted on said forward end of said reflector and made of a light-transmissive plastic which is degraded by said UV
radiation.
radiation.
7. The assembly of claim 6 wherein said UV
absorbing coating is substantially nonabsorbent and transparent to visible light radiation.
absorbing coating is substantially nonabsorbent and transparent to visible light radiation.
8. The assembly of claim 7 wherein a UV absorbing coating is disposed on that surface of said lens which is interior of said assembly.
9. The assembly of claim 8 wherein said UV
absorbing coating on said lens is substantially nonabsorbent and transparent to visible light radiation.
absorbing coating on said lens is substantially nonabsorbent and transparent to visible light radiation.
10. The assembly of claim 9 wherein the optical center of said lamp is located at about the focal point of said reflector.
11. The assembly of claim 10 wherein said lamp is an arc discharge lamp.
12. The assembly of claim 11 wherein said lamp is a miniature metal halide arc discharge lamp.
13. An automotive lamp, reflector and plastic lens assembly wherein said lamp is an arc discharge lamp which emits both UV and visible radiation and is mounted within said reflector with the optical center of said lamp at about the focal point of said reflector, said reflector having a forward, light projecting end and an internal reflecting surface for reflecting said visible light radiation forward of said reflector, with a UV absorbing coating disposed on said reflecting surface and with lens mounted on said forward end of said reflector and being made of a visible light-transmitting plastic which is degraded by said UV radiation emitted by said lamp.
14. The assembly of claim 13 wherein said UV
absorbing coating is substantially nonabsorbent and transparent to visible light radiation.
absorbing coating is substantially nonabsorbent and transparent to visible light radiation.
15. The assembly of claim 13 wherein a UV
absorbing coating is disposed on that surface of said lens interior of said assembly.
absorbing coating is disposed on that surface of said lens interior of said assembly.
16. The assembly of claim 15 wherein said coating is substantially nonabsorbent and transparent to visible light radiation.
17. The assembly of claim 13 wherein a light shield is disposed between said lamp and said lens to insure that substantially all of said forward projected visible light is projected from said reflecting surface.
18. The assembly of claim 14 wherein a light shield is disposed between said lamp and said lens to insure that substantially all of said forward projected visible light is projected from said reflecting surface.
19. The assembly of claim 16 wherein a light shield is disposed between said lamp and said lens to insure that substantially all of said forward projected visible light is projected from said reflecting surface.
20. The assembly of claim 13 wherein said reflector is made of plastic.
21. The invention as defined in any of the preceding claims including any further features of novelty disclosed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US66982091A | 1991-03-15 | 1991-03-15 | |
| US669,820 | 1991-03-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2062017A1 true CA2062017A1 (en) | 1992-09-16 |
Family
ID=24687880
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2062017 Abandoned CA2062017A1 (en) | 1991-03-15 | 1992-02-27 | Automotive arc headlamp with reduced uv emission |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0503976B1 (en) |
| JP (1) | JP2647595B2 (en) |
| CA (1) | CA2062017A1 (en) |
| DE (1) | DE69205862T2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7124499B2 (en) | 2003-07-29 | 2006-10-24 | Simpler Networks Inc. | Apparatus for installing a length of wire |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5586015A (en) * | 1993-06-18 | 1996-12-17 | General Electric Company | Sports lighting luminaire having low glare characteristics |
| DE19608042A1 (en) * | 1996-03-02 | 1997-09-04 | Imab Stiftung | Simple UV filter lamp |
| DE19907365A1 (en) * | 1999-02-20 | 2001-01-04 | Matthias Rettig | Xenon headlamp for automobile has filters or filter foils used for absorbing selected light components to prevent dazzle of oncoming automobile driver |
| JP4524877B2 (en) * | 2000-07-17 | 2010-08-18 | コニカミノルタホールディングス株式会社 | Eyeglass lenses |
| JP2015133170A (en) * | 2012-04-27 | 2015-07-23 | ヤマハ発動機株式会社 | Vehicle headlight unit and vehicle including the same |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4386292A (en) * | 1980-07-02 | 1983-05-31 | Gte Products Corporation | Projection lamp comprising single ended arc discharge lamp and an interference filter |
| US4524299A (en) * | 1982-04-08 | 1985-06-18 | North American Philips Corporation | Fluorescent sunlamp having controlled ultraviolet output |
| US4604680A (en) * | 1985-04-25 | 1986-08-05 | Gte Products Corporation | Infrared floodlight |
| CA2050179A1 (en) * | 1990-08-31 | 1992-03-01 | Yukio Wakimizu | Vehicular headlamp of the projection type |
-
1992
- 1992-02-27 CA CA 2062017 patent/CA2062017A1/en not_active Abandoned
- 1992-03-10 JP JP4051032A patent/JP2647595B2/en not_active Expired - Lifetime
- 1992-03-13 DE DE1992605862 patent/DE69205862T2/en not_active Expired - Fee Related
- 1992-03-13 EP EP19920302221 patent/EP0503976B1/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7124499B2 (en) | 2003-07-29 | 2006-10-24 | Simpler Networks Inc. | Apparatus for installing a length of wire |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0503976A1 (en) | 1992-09-16 |
| EP0503976B1 (en) | 1995-11-08 |
| DE69205862T2 (en) | 1996-06-20 |
| JPH04355042A (en) | 1992-12-09 |
| DE69205862D1 (en) | 1995-12-14 |
| JP2647595B2 (en) | 1997-08-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |