US3654463A - Phosphorescent devices - Google Patents

Phosphorescent devices Download PDF

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Publication number
US3654463A
US3654463A US4006A US3654463DA US3654463A US 3654463 A US3654463 A US 3654463A US 4006 A US4006 A US 4006A US 3654463D A US3654463D A US 3654463DA US 3654463 A US3654463 A US 3654463A
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United States
Prior art keywords
phosphor
emission
pump
wavelength
wavelengths
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Expired - Lifetime
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US4006A
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English (en)
Inventor
Joseph Edward Geusic
Frederick William J Ostermayer
Le Grand Gerard Van Uitert
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AT&T Corp
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Bell Telephone Laboratories Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
    • F21K2/00—Non-electric light sources using luminescence; Light sources using electrochemiluminescence
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K11/00—Luminescent materials, e.g. electroluminescent or chemiluminescent
    • C09K11/02—Use of particular materials as binders, particle coatings or suspension media therefor
    • C09K11/025—Use of particular materials as binders, particle coatings or suspension media therefor non-luminescent particle coatings or suspension media

Definitions

  • ABSTRACT Incoherent light sources depending on phosphors which may simultaneously emit at more than one wavelength are provided with multiple dielectric coatings to suppress a portion of the emission and thereby enhance the remainder.
  • the use of such coatings with frequency up-converting phosphors as well as down-converting phosphors is described.
  • Incoherent light sources based on phosphor emission are already in prevalent use and many new uses are contemplated. Such sources depend upon a variety of pump means as, for example, electron bombardment in cathode ray tubes; d.c. electric biasing in junction devices, such as those using gallium arsenide; and light pumping as in a variety of display devices.
  • the latter category includes higher frequency pumping in most common devices and lower frequency pumping as in second photon devices. See Bulletin of the American Physical Society, Series ll, Vol. 13, No.4, p. 687, Paper I-IK7.
  • Phosphor materials are of many types, some inorganic, some organic; some emit over rather narrow bandwidths, some over broad bandwidths.
  • a situation may arise in which part of the pump energy is converted to undesired emission.
  • This undesired emission may be within or without the visible spectrum.
  • a specific example of recent concern has to do with second photon sources utilizing long wavelength pumps.
  • a forward biased GaAs diode is used to pump a rare earth-containing, second photon phosphor to produce visible emission.
  • Such devices operate efficiently at green and red wavelengths, difficulty has been encountered in fabricating an efficient blue source.
  • a blue source is desired for the construction of a three-color display system.
  • thulium-containing materials (the initial absorption function being performed by ytterbium) emit blue light when pumped by the infrared emission from the diode, a significant part of the pump energy is converted to a different wavelength of near infrared emission. As a result, the efficiency of conversion to blue is diminished. Many other similar examples exist.
  • a further complication resulting in inefficiency in phosphorescent devices is concerned with inefficient utilization of pump energy.
  • absorption coefficients for different involved wavelengths may dictate different optimum thicknesses for emission and for pump energy.
  • dimension optimization for emission may result in inefficient absorption of pump energy.
  • multilayered coatings of transparent materials of critical thickness and refractive indices partially or totally encompassing phosphor materials result in suppression of energy of one or more wavelengths while permitting transmission of energy of one or more other wavelengths.
  • This is a general solution which results in improvement of efficiency of incoherent phosphorescent devices in any of the classes set forth above.
  • pumping efficiency is improved by preventing escape of part of the pump energy or even by creating resonant conditions for such pump energy.
  • significant improvement in emission is brought about by suppression of one or more emission wavelengths to enhance at least one other wavelength in phosphors having relevant emission spectra.
  • FIG. 1 is an energy level diagram in ordinate units of wavenumbers for an appropriate second-photon phosphor system illustrative of systems suitable for improvement in accordance with the inventive principles;
  • FIG. 2 is a sectional view of a structure showing improved emission efficiency in accordance with the invention
  • FIG. 3 on coordinates of transmittance in percent, and wavelength in microns illustrates the relationship of these coordinates for a particular layered structure
  • FIG. 4 in ordinate units of wavenumbers is an energy diagram illustrating a down-converting phosphor system with multiple emission lines, the efficiency of which may be improved in accordance with the invention
  • FIG. 5 is a sectional view of a phosphor layer dielectrically coated in accordance with the invention.
  • FIG. 6 is a sectional view of a portion of a structure alternative to that of FIG. 5.
  • the ytterbium-thulium, second-photon phosphor For illustrative purposes, a detailed description is set forth in terms of the ytterbium-thulium, second-photon phosphor.
  • This particular system is of interest as a blue light source, for example, as an indicator light or a portion of a display screen with light pumping at a suitable infrared wavelength. Since absorption is relatively narrow, this material is particularly suitable for use with a narrow band emitting pump such as a laser or a forward biased incoherent diode. The prime example of the latter at this writing is the gallium arsenide diode.
  • FIG. 1 In the ytterbium-thulium system (suitable hosts include yttrium fluoride), infrared excited blue emission is produced by a three-step sequential excitation.
  • the efficiency of the infrared excited blue emission from level 3 is approximately 0.1 percent blue power out intrared power in At present, the blue emission is limited to this low value because significant emission at 8,000 A. from level 2 occurs. In fact, the emission from 8,000 A. is from 4 to 10 percent efficient. A technique to improve the blue emission at the expense ofthe 8,000 A.
  • emission is to provide a reflective coating on the phosphor so as to effectively increase the radiative lifetime of level 2, thus increasing the probability of excitation of atoms to level 3 as compared to the probability of the 8,000 A. radiative transition.
  • Tm the 8,000 A. transition occurs to the ground state; and in this case, if a coating of reflectivity R is used, the effective radiative lifetime can be increased to where -r is the normal radiative lifetime of the Tm "2 level. Since with multilayer coatings a reflectivity of greater than percent is easily achievable, emission at 4,800 A. (blue) is increased by at least a factor of 10.
  • FIGS. 2 and 3 Several methods of entrapping the 8,000 A. radiation to improve the blue emission are discussed in FIGS. 2 and 3. In FIG.
  • YF zYbjlm is in the form of a thin transparent coating on the diode 2 which may be Si-GaAs.
  • the dome surface 3 of the diode and the outer surface 4 of the phosphor have been coated with a multilayer coating which is reflective at 8,000 A. and transparent at 4,800 A.
  • a fifteen-layer coating which can be-used is represented in FIG. 3.
  • the coating consists of a thirteen-layer, l/4 0.57 1,), high and low index stack in which the high index layer H ZnS and the low index layer L MgF On either end, a 56). layer (H/2) of the high index material is used.
  • the general characteristic of such a coating is also shown. If also the coatings are partially reflective at the pump frequency (093p for GaAs diodes) one can get an even further enhancement because the intensity of the 0.93 p. radiation in the phosphor is effectively increased by a factor proportional to the number of internal reflections.
  • Enhancement at 8,000 A is discussed.
  • the coating is highly reflecting at 4,880 A if the layers of the same dielectric structure described above are VAX at 2,800 A. or 700 A. thick. Such a coating reflects 4,800 A. and transmits 8,000 A. and 0.93u.
  • the Tm phosphor can be used to pump YAG:Nd which absorbs at 8,000 A. without undue loss as blue emission (4,880 A.). Normal operation is 300 Amperes/cm in a GaAs diode.
  • Host materials may be simple fluorides or more complex media shown to enhance operation inaccordance with a variety of mechanisms.
  • the pump may be a conventional Hg-Arc source.
  • FIG. 5 depicts a phosphor layer 10 covered by coatings 11 and 12. Coating materials are selected in accordance with the considerations set forth above.
  • the phosphor material 15 is particulate and each particle is coated with multiple layers 16 to accomplish the end described. While present techniques do not produce coatings of the thickness uniformity which may be accomplished on massive smooth surfaces, procedures are available for producing coatings which, while they may not optimize, nevertheless improve emission efficiency. Such techniques include evaporation, sputtering and various other deposition techniques.
  • the general requirement of the invention is that at least one emitting surface of a phosphor be contacted by at least two layers of materials of differing refractive indices so chosen as to unequally suppress a portion of the spectrum relative to another such portion. Suitable materials are necessarily transparent to all concerned wavelengths, it being considered that an absorption of 5 percent at any concerned wavelength is the maximum permitted. The number of layers, their indices and thickness, all depend on the particular circumstances involved.
  • Incoherent phosphorescent emission source comprising a phosphor adapted to at least partially transmit electromagnetic radiation of different wavelengths, characterized in that said phosphor is provided with a medium at least partially encompassing said phosphor, said medium consisting essentially of at least two successive layers, said layers being of such thicknesses and having such refractive indices as to suppress one of the said wavelengths relative to the other in which said phosphor is of such nature as to produce at least one wavelength which is shorter that that of a pump.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • General Engineering & Computer Science (AREA)
  • Luminescent Compositions (AREA)
US4006A 1970-01-19 1970-01-19 Phosphorescent devices Expired - Lifetime US3654463A (en)

Applications Claiming Priority (1)

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US400670A 1970-01-19 1970-01-19

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US (1) US3654463A (fr)
BE (1) BE761638A (fr)
CA (1) CA924818A (fr)
DE (1) DE2102120A1 (fr)
FR (1) FR2075671A5 (fr)
NL (1) NL7100573A (fr)

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849628A (en) * 1973-07-25 1974-11-19 Xerox Corp Non-contact temperature sensor for a roll fuser of a xerographic reproduction apparatus
US3946203A (en) * 1974-06-26 1976-03-23 Recognition Equipment Incorporated Optical reader fluorescence control
US3959655A (en) * 1975-02-06 1976-05-25 Eastman Kodak Company Light source for optical sound recording and reproduction apparatus
US4047033A (en) * 1974-10-25 1977-09-06 Ab Id-Kort Checking an identity, authority or check document or the like
US4061578A (en) * 1976-04-05 1977-12-06 Marcos Kleinerman Infrared detection and imaging, method and apparatus
JPS57166529A (en) * 1981-04-07 1982-10-14 Omron Tateisi Electronics Co Method and device for measuring temperature
US4442170A (en) * 1980-05-30 1984-04-10 Gao Gesellschaft Fur Automation Und Organisation Mbh. Security document with security features in the form of luminescing substances
US4451530A (en) * 1980-05-30 1984-05-29 Gao Gesellschaft Fur Automation Und Organisation Mbh. Security paper with authenticity features in the form of luminescing substances
US4598205A (en) * 1980-05-30 1986-07-01 Gao Gesellschaft Fur Automation Und Organisation Mbh Security paper with authenticity features in the form of substances luminescing only in the invisible region of the optical spectrum and process for testing the same
US4947850A (en) * 1988-03-11 1990-08-14 Trustees Of The University Of Pennsylvania Method and apparatus for imaging an internal body portion of a host animal
US5166948A (en) * 1991-06-19 1992-11-24 Polaroid Corporation Optically pumped up converting light source
US6091563A (en) * 1997-09-26 2000-07-18 Iomega Corporation Latent illuminance discrimination marker system for data storage cartridges
US6181662B1 (en) 1997-09-26 2001-01-30 Iomega Corporation Latent irradiance discrimination method and marker system for cartridgeless data storage disks
US6201662B1 (en) 1998-09-25 2001-03-13 Iomega Corporation Latent illuminance discrimination marker with reflective layer for data storage cartridges
US6245259B1 (en) 1996-09-20 2001-06-12 Osram Opto Semiconductors, Gmbh & Co. Ohg Wavelength-converting casting composition and light-emitting semiconductor component
US6264107B1 (en) 1997-09-26 2001-07-24 Iomega Corporation Latent illuminance discrimination marker system for authenticating articles
US6354501B1 (en) 1998-11-18 2002-03-12 Crossoff Incorporated Composite authentication mark and system and method for reading the same
US6359745B1 (en) 1997-09-26 2002-03-19 Iomega Corporation Latent illuminance discrimination marker system for data storage cartridges
US6536672B1 (en) * 1998-11-18 2003-03-25 Dna Technologies, Inc. Product authentication system and method
US6613247B1 (en) 1996-09-20 2003-09-02 Osram Opto Semiconductors Gmbh Wavelength-converting casting composition and white light-emitting semiconductor component
US20050127385A1 (en) * 1996-06-26 2005-06-16 Osram Opto Semiconductors Gmbh & Co., Ohg, A Germany Corporation Light-radiating semiconductor component with a luminescence conversion element
EP1425772A4 (fr) * 2001-03-30 2007-04-04 Canon Kk Structure et fabrication d'un dispositif electroluminescent comprenant des particules electroluminescentes partiellement revetues

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5372669A (en) 1985-02-05 1994-12-13 Avery Dennison Corporation Composite facestocks and liners

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2904689A (en) * 1956-06-01 1959-09-15 United States Radium Corp Fluorescent x-ray screens
US3484606A (en) * 1967-07-13 1969-12-16 Mid Continent Mfg Co Radiation responsive electrical device having an extended spectral response characteristic

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2904689A (en) * 1956-06-01 1959-09-15 United States Radium Corp Fluorescent x-ray screens
US3484606A (en) * 1967-07-13 1969-12-16 Mid Continent Mfg Co Radiation responsive electrical device having an extended spectral response characteristic

Cited By (42)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3849628A (en) * 1973-07-25 1974-11-19 Xerox Corp Non-contact temperature sensor for a roll fuser of a xerographic reproduction apparatus
US3946203A (en) * 1974-06-26 1976-03-23 Recognition Equipment Incorporated Optical reader fluorescence control
US4047033A (en) * 1974-10-25 1977-09-06 Ab Id-Kort Checking an identity, authority or check document or the like
US3959655A (en) * 1975-02-06 1976-05-25 Eastman Kodak Company Light source for optical sound recording and reproduction apparatus
US4061578A (en) * 1976-04-05 1977-12-06 Marcos Kleinerman Infrared detection and imaging, method and apparatus
US4442170A (en) * 1980-05-30 1984-04-10 Gao Gesellschaft Fur Automation Und Organisation Mbh. Security document with security features in the form of luminescing substances
US4451530A (en) * 1980-05-30 1984-05-29 Gao Gesellschaft Fur Automation Und Organisation Mbh. Security paper with authenticity features in the form of luminescing substances
US4598205A (en) * 1980-05-30 1986-07-01 Gao Gesellschaft Fur Automation Und Organisation Mbh Security paper with authenticity features in the form of substances luminescing only in the invisible region of the optical spectrum and process for testing the same
JPS57166529A (en) * 1981-04-07 1982-10-14 Omron Tateisi Electronics Co Method and device for measuring temperature
US4710033A (en) * 1981-04-07 1987-12-01 Omron Tateisi Electronics Co. Temperature measurement system
US4947850A (en) * 1988-03-11 1990-08-14 Trustees Of The University Of Pennsylvania Method and apparatus for imaging an internal body portion of a host animal
US5166948A (en) * 1991-06-19 1992-11-24 Polaroid Corporation Optically pumped up converting light source
US7151283B2 (en) 1996-06-26 2006-12-19 Osram Gmbh Light-radiating semiconductor component with a luminescence conversion element
US20050127385A1 (en) * 1996-06-26 2005-06-16 Osram Opto Semiconductors Gmbh & Co., Ohg, A Germany Corporation Light-radiating semiconductor component with a luminescence conversion element
US9196800B2 (en) 1996-06-26 2015-11-24 Osram Gmbh Light-radiating semiconductor component with a luminescence conversion element
US7629621B2 (en) 1996-06-26 2009-12-08 Osram Gmbh Light-radiating semiconductor component with a luminescence conversion element
US20080149958A1 (en) * 1996-06-26 2008-06-26 Ulrike Reeh Light-Radiating Semiconductor Component with a Luminescence Conversion Element
US7345317B2 (en) 1996-06-26 2008-03-18 Osram Gmbh Light-radiating semiconductor component with a luminescene conversion element
US7126162B2 (en) 1996-06-26 2006-10-24 Osram Gmbh Light-radiating semiconductor component with a luminescence conversion element
US7078732B1 (en) 1996-06-26 2006-07-18 Osram Gmbh Light-radiating semiconductor component with a luminescence conversion element
US20050231953A1 (en) * 1996-06-26 2005-10-20 Osram Gmbh Light-radiating semiconductor component with a luminescence conversion element
US20050161694A1 (en) * 1996-06-26 2005-07-28 Osram Gmbh Light-radiating semiconductor component with a luminescence conversion element
US7276736B2 (en) 1996-09-20 2007-10-02 Osram Gmbh Wavelength-converting casting composition and white light-emitting semiconductor component
US8071996B2 (en) 1996-09-20 2011-12-06 Osram Gmbh Wavelength-converting casting composition and light-emitting semiconductor component
US20040084687A1 (en) * 1996-09-20 2004-05-06 Osram Opto Semiconductors Gmbh Wavelength-converting casting composition and white light-emitting semiconductor component
US6613247B1 (en) 1996-09-20 2003-09-02 Osram Opto Semiconductors Gmbh Wavelength-converting casting composition and white light-emitting semiconductor component
US6592780B2 (en) 1996-09-20 2003-07-15 Osram Opto Semiconductors Gmbh Wavelength-converting casting composition and white light-emitting semiconductor component
US20040016908A1 (en) * 1996-09-20 2004-01-29 Klaus Hohn Wavelength-converting casting composition and white light-emitting semiconductor component
US7709852B2 (en) 1996-09-20 2010-05-04 Osram Gmbh Wavelength-converting casting composition and light-emitting semiconductor component
US6245259B1 (en) 1996-09-20 2001-06-12 Osram Opto Semiconductors, Gmbh & Co. Ohg Wavelength-converting casting composition and light-emitting semiconductor component
US6277301B1 (en) 1996-09-20 2001-08-21 Osram Opto Semiconductor, Gmbh & Co. Ohg Method of producing a wavelength-converting casting composition
US20100176344A1 (en) * 1996-09-20 2010-07-15 Hoehn Klaus Wavelength-converting casting composition and light-emitting semiconductor component
US7235189B2 (en) 1996-09-20 2007-06-26 Osram Gmbh Method of producing a wavelength-converting casting composition
US20070216281A1 (en) * 1996-09-20 2007-09-20 Klaus Hohn Wavelength-converting casting composition and light-emitting semiconductor component
US6181662B1 (en) 1997-09-26 2001-01-30 Iomega Corporation Latent irradiance discrimination method and marker system for cartridgeless data storage disks
US6091563A (en) * 1997-09-26 2000-07-18 Iomega Corporation Latent illuminance discrimination marker system for data storage cartridges
US6264107B1 (en) 1997-09-26 2001-07-24 Iomega Corporation Latent illuminance discrimination marker system for authenticating articles
US6359745B1 (en) 1997-09-26 2002-03-19 Iomega Corporation Latent illuminance discrimination marker system for data storage cartridges
US6201662B1 (en) 1998-09-25 2001-03-13 Iomega Corporation Latent illuminance discrimination marker with reflective layer for data storage cartridges
US6536672B1 (en) * 1998-11-18 2003-03-25 Dna Technologies, Inc. Product authentication system and method
US6354501B1 (en) 1998-11-18 2002-03-12 Crossoff Incorporated Composite authentication mark and system and method for reading the same
EP1425772A4 (fr) * 2001-03-30 2007-04-04 Canon Kk Structure et fabrication d'un dispositif electroluminescent comprenant des particules electroluminescentes partiellement revetues

Also Published As

Publication number Publication date
FR2075671A5 (fr) 1971-10-08
BE761638A (fr) 1971-06-16
CA924818A (en) 1973-04-17
NL7100573A (fr) 1971-07-21
DE2102120A1 (de) 1971-07-29

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