GB2276032A - A Radiation source - Google Patents

A Radiation source Download PDF

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Publication number
GB2276032A
GB2276032A GB9304659A GB9304659A GB2276032A GB 2276032 A GB2276032 A GB 2276032A GB 9304659 A GB9304659 A GB 9304659A GB 9304659 A GB9304659 A GB 9304659A GB 2276032 A GB2276032 A GB 2276032A
Authority
GB
United Kingdom
Prior art keywords
radiation source
array
diodes
light emitting
preceding
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.)
Granted
Application number
GB9304659A
Other versions
GB9304659D0 (en
GB2276032B (en
Inventor
Peter Brian Hart
Geoffrey Lidgard
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Prp Optoelectronics Ltd
Original Assignee
PRP OPTOELECTRONICS Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by PRP OPTOELECTRONICS Ltd filed Critical PRP OPTOELECTRONICS Ltd
Priority to GB9304659A priority Critical patent/GB2276032B/en
Publication of GB9304659D0 publication Critical patent/GB9304659D0/en
Publication of GB2276032A publication Critical patent/GB2276032A/en
Application granted granted Critical
Publication of GB2276032B publication Critical patent/GB2276032B/en
Anticipated expiration legal-status Critical
Application status is Expired - Fee Related legal-status Critical

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L25/00Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
    • H01L25/03Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L51/00, e.g. assemblies of rectifier diodes
    • H01L25/04Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L51/00, e.g. assemblies of rectifier diodes the devices not having separate containers
    • H01L25/075Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L51/00, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
    • H01L25/0753Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L51/00, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21KNON-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
    • F21K9/00Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21WINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO USES OR APPLICATIONS OF LIGHTING DEVICES OR SYSTEMS
    • F21W2111/00Use or application of lighting devices or systems for signalling, marking or indicating, not provided for in codes F21W2102/00 – F21W2107/00
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21YINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2105/00Planar light sources
    • F21Y2105/10Planar light sources comprising a two-dimensional array of point-like light-generating elements
    • F21Y2105/14Planar light sources comprising a two-dimensional array of point-like light-generating elements characterised by the overall shape of the two-dimensional array
    • F21Y2105/16Planar light sources comprising a two-dimensional array of point-like light-generating elements characterised by the overall shape of the two-dimensional array square or rectangular, e.g. for light panels
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21LIGHTING
    • F21YINDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21S and F21V, RELATING TO THE FORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THE LIGHT EMITTED
    • F21Y2115/00Light-generating elements of semiconductor light sources
    • F21Y2115/10Light-emitting diodes [LED]
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/0001Technical content checked by a classifier
    • H01L2924/0002Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/64Heat extraction or cooling elements
    • H01L33/648Heat extraction or cooling elements the elements comprising fluids, e.g. heat-pipes

Abstract

A radiation source for emitting high intensity light close to the emitting surface thereof, includes a thermally conductive substrate (3); a densely packed two dimensional array (1) of light emitting diodes formed on a surface of the substrate, the emission spectrum of the array being matched to that required by a particular application of the radiation source; means for applying relatively high drive currents to each of the diodes; and heat sinking means (8), such as a water cooled heat sink, for dissipating the heat generated by the diodes. <IMAGE>

Description

A RADIATION SOURCE The invention relates to a radiation source for emitting high intensity light close to the emitting surface thereof.

It is known to use various types of laser in applications where high levels of illumination are required at specific wavelengths in the visible, or infra-red, regions of the spectrum. In some of these applications, there are significant disadvantages in the use of lasers because the laser beam produces a very intense local radiation level rather than a more diffuse level over an area of several square centimetres. In addition, lasers for some regions of the spectrum are very expensive and require specialist personnel for there operation and maintenance.

It is an object of the present invention to overcome the foregoing problems by providing a low cost, non-lasing, radiation source including a light emitting diode array for emitting high intensity light close to the emitting surface thereof.

The invention provides a radiation source for emitting high intensity light close to the emitting surface thereof, including a thermally conductive substrate; a densely packed two dimensional array of light emitting diodes formed on a surface of the substrate, the emission spectrum of the array being matched to that required by a particular application of the radiation source; means for applying relatively high drive currents to each of the diodes; and heat sinking means for dissipating the heat generated by the diodes.

In some applications, the radiation levels required are typically in the range 10 to 200 joules/cm2, depending on the particular application, and this needs to be achieved at an intensity in the range from 100 to 200 mW/cm2 for periods between 100 to 1000 seconds. The radiation source according to the present invention is capable of achieving these radiation levels.

The front surface of the LED array is preferably encapsulated with a thin layer of an encapsulant, for example, transparent silicone, to provide mechanical strength, and the array can include optical means, for example, micro-lenses, for increasing the intensity of the local radiation close to the front surface of the array.

The diodes of the array can be powered by a simple constant current supply connected to a suitably patterned metallisation layer formed on the surface of the substrate and including an anode track and a cathode track. The substrate is preferably of alumina.

According to one aspect of the present invention, the quantum efficiency of the light emitting diodes is in the range 1 to 5 %.

According to another aspect of the present invention the light emitting diodes are in the form of GaAlAs light emitting diode chips, and have a quantum efficiency of the order of 2%.

According to another aspect of the present invention the size of the array is of the order of 1.0 x 1.0 cm2, and each of the chips are 0.3 x 0.3 mm2, and have a pitch of 0.5 mm.

According to another aspect of the invention, the mean drive current of each chip is in the range 50 to 100 mA, and the total array dissipation is in the range 50 to 100 Watts.

According to another aspect of the invention the temperature rise of the array is limited to 200C by the heat sinking means which are preferably in the form of a water cooled heat sink.

According to another aspect of the invention the light emitting diodes are in the form of InGaAlP light emitting diode chips.

The invention also provides a method of irradiating a region of a member with high intensity illumination utilising a radiation source according to the present invention having the front surface thereof situated in close proximity to the said region of the member.

The forgoing and other features according to the present invention will be better understood from the following description with reference to the accompanying drawings, in which: Figure 1 illustrates, in a plan view, a radiation source according to the present invention, and Figure 2 illustrates, in a cross-sectional side elevation, the radiation source illustrated in Figure 1.

It is normally assumed that the levels of radiation referred to above cannot be achieved with non-lasing light emitting diodes (LEDs), because of their relatively low efficiency, i.e. around 1% or less, and the fact that the light emission is over a large solid angle, unless specially encapsulated or lensed.

However, the required intensity levels can be obtained close to the emitting surface of the LED array of the radiation source according to the present invention.

The- radiation source according to the present invention utilises a densely packed LED array that is constructed using LEDs having quantum efficiencies in the range 1 to 5% and that is driven at high current levels. The LED array is provided with adequate heat-sinking in order to prevent overheating. Typically, the heat sinking can be effected by a cooled heat sink, for example a water cooled heat sink.

The radiation source illustrated in a plan view in Figure 1 of the accompanying drawings includes a densely packed two dimensional array of GaAlAs LED chips 1 having a quantum efficiency of the order of 2%. The emission spectrum of the LED chips 1 is closely matched to that which is required for a particular application of the radiation source.

The LED chips 1 are 0.3 x 0.3 mm2, and are assembled in an array with a pitch of 0.5 mm. The overall size of the array is of the order of 1.0 x 1.0 cm2.

As is best illustrated in Figure 2 of the accompanying drawings, the array of LED chips 1 are assembled on the surface 2 of a substrate 3 of good thermal conductivity, for example, alumina.

A suitably patterned metalisation layer formed on the surface 2 and consisting of an anode track 4 and a cathode track 5 provides the required interconnections for the chips 1 so that the mean drive current of each diode can be in the range 50 to 100 mA, and the total array dissipation in the range 50 to 100 Watts.

The comb-like structure of the anode track 4 is such that each of the limbs 6 provides the anode connection for two adjacent rows of the LEDs 1, and the narrower limbs 7 of the comb-like structure of the cathode track 5 are situated, one on each side, of the limbs 7.

The two outer limbs 7 provide the cathode connections for respective ones of the first and last row of LEDs and the other limbs 7 each provide the cathode connections for adjacent rows of LEDs As illustrated in Figure 2 of the accompanying drawings, the radiation source according to the present invention includes a cooled heat sink 8, for example, a water cooled heat sink, secured in thermal contact with the substrate 2. The heat sink 8 is adapted to limit the temperature rise of the LED array to a level of the order of 200C.

As is also illustrated in Figure 2 of the accompanying drawings, the LED array is encapsulated with a thin layer 9 of a suitabie encapsulant, for example, transparent silicone, in order to provide mechanical protection for the LED array, whilst at the same time making it possible to bring the emitting area of the LED array close to the region requiring irradiation.

The LED array of the radiation source according to the present invention can be fabricated from other LED chip materials, for example, InGaAlP could be used to provide effective emission at a selected wavelength.

The radiation source according to the present invention could also use optical techniques, such as micro-lenses, in order to further increase the local radiation intensity close to the surface of the LED array.

The essential aspects of the radiation source according to the present invention is the use of LEDs of adequate efficiency, the careful matching of the LED emission spectrum to that required by the particular application of the radiation source, and the good design of the LED assembly and packaging to ensure that heat is conducted away from the diodes.

The radiation source according to the present invention can used in any application where localised irradiation with a high intensity light of a selected wavelength is required.

Claims (16)

1. A radiation source for emitting high intensity light close to the emitting surface thereof,, including a thermally conductive substrate; a densely packed two dimensional array of light emitting diodes formed on a surface of the substrate, the emission spectrum of the array being matched to that required by a particular application of the radiation source; means for applying relatively high drive currents to each of the diodes; and heat sinking means for dissipating the heat generated by the diodes.
2. A radiation source as claimed in claim 1 wherein the quantum efficiency of the light emitting diodes is in the range 1 to 5 %.
3. A radiation source as claimed in claim 1 or claim 2 wherein the light emitting diodes are in the form of GaAlAs light emitting diode chips, and wherein the quantum efficiency of the chips is of the order of 2%.
4. A radiation source as claimed in claim 3 wherein the size of the array is of the order of 1.0 x 1.0 cm2, and wherein each of the chips are 0.3 x 0.3 mm2, and have a pitch of 0.5 mm.
5. A radiation source as claimed in claim 3 or claim 4 wherein the mean drive current of each chip is in the range 50 to 100 mA, and wherein the total array dissipation is in the range 50 to 100 Watts.
6. A radiation source as claimed in any one of the claims 3 to 5 wherein the temperature rise of the array is limited to 20 C by the heat sinking means.
7. A radiation source as claimed in claim 1 or claim 2 wherein the light emitting diodes are in the form of InGaAlP light emitting diode chips.
8. radiation source as claimed in any one of the preceding claims wherein the front surface of the array is encapsulated with a thin layer of encapsulant to provide mechanical strength.
9. A radiation source as claimed in claim 8 wherein the encapsulant is transparent silicone.
10. A radiation source as claimed in any one of the preceding claims wherein the thermally conductive substrate is an alumina substrate.
11. A radiation source as claimed in any one of the preceding claims including optical means for increasing the intensity of the local radiation close to the front surface of the array.
12. A radiation source as claimed in claim 11 wherein the optical means include micro-lenses.
13. A radiation source as claimed in any one of the preceding claims wherein the diodes of the array are powered by a constant current supply.
14. A radiation source as claimed in any one of the preceding claims wherein the heat sinking means include a water cooled heat sink secured in thermal contact with the substrate.
15. A radiation source for emitting high intensity light close to the emitting surface thereof substantially as hereinbefore described with reference to the accompanying drawings.
16. A method of irradiating a region of a member with high intensity illumination utilising a radiation source as claimed in any one of the preceding claims having the front surface thereof situated in close proximity to the said region of the member.
GB9304659A 1993-03-08 1993-03-08 High intensity light source Expired - Fee Related GB2276032B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB9304659A GB2276032B (en) 1993-03-08 1993-03-08 High intensity light source

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB9304659A GB2276032B (en) 1993-03-08 1993-03-08 High intensity light source

Publications (3)

Publication Number Publication Date
GB9304659D0 GB9304659D0 (en) 1993-04-28
GB2276032A true GB2276032A (en) 1994-09-14
GB2276032B GB2276032B (en) 1997-04-16

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Family Applications (1)

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GB9304659A Expired - Fee Related GB2276032B (en) 1993-03-08 1993-03-08 High intensity light source

Country Status (1)

Country Link
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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2331399A (en) * 1997-11-14 1999-05-19 Prp Optoelectronics Limited High intensity light source
WO2001049164A1 (en) * 1999-12-29 2001-07-12 Keymed (Medical & Industrial Equipment) Ltd Light source for borescopes and endoscopes
WO2002005351A1 (en) * 2000-07-12 2002-01-17 Tridonic Optoelectronics Gmbh Led light source
WO2002005350A1 (en) * 2000-07-12 2002-01-17 Tridonic Optoelectronics Gmbh Method for producing an led light source
WO2002005357A1 (en) * 2000-07-10 2002-01-17 Osram Opto Semiconductors Gmbh Led module, method for producing the same and the use thereof
GB2370992A (en) * 2000-03-23 2002-07-17 Photo Therapeutics Ltd A therapeutic light source
WO2002086972A1 (en) * 2001-04-23 2002-10-31 Plasma Ireland Limited Illuminator
EP1523041A1 (en) * 2004-12-08 2005-04-13 Jeffrey Chen Light emitting diode assembly having high-performance heat dissipation means
DE102005036275A1 (en) * 2005-08-02 2007-02-08 Berchtold Holding Gmbh surgical light
WO2008141500A1 (en) * 2007-05-18 2008-11-27 Hujun Huang A circuit board for heat dispersion
WO2009082865A1 (en) * 2007-12-30 2009-07-09 Foshan Nationstar Optoelectronics Limited Liability Company Led plane light source for universial illumination
EP2337077A1 (en) * 2000-10-16 2011-06-22 OSRAM Opto Semiconductors GmbH LED Module
WO2013035024A1 (en) * 2011-09-06 2013-03-14 Koninklijke Philips Electronics N.V. Topology of distributing and connecting leds in a large area matrix

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4394600A (en) * 1981-01-29 1983-07-19 Litton Systems, Inc. Light emitting diode matrix
EP0202335B1 (en) * 1984-11-15 1989-10-25 Japan Traffic Management Technology Association Signal light unit having heat dissipating function
JPH02252273A (en) * 1989-03-27 1990-10-11 Furukawa Electric Co Ltd:The Junction of led array chip and heat sink base
GB2246471A (en) * 1988-08-23 1992-01-29 Nobuo Mikoshiba Cooling semiconductor devices
JPH04245684A (en) * 1991-01-31 1992-09-02 Iwasaki Electric Co Ltd Light emitting diode lamp
JPH10154542A (en) * 1996-11-22 1998-06-09 Nec Corp Electric connector

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4394600A (en) * 1981-01-29 1983-07-19 Litton Systems, Inc. Light emitting diode matrix
EP0202335B1 (en) * 1984-11-15 1989-10-25 Japan Traffic Management Technology Association Signal light unit having heat dissipating function
GB2246471A (en) * 1988-08-23 1992-01-29 Nobuo Mikoshiba Cooling semiconductor devices
JPH02252273A (en) * 1989-03-27 1990-10-11 Furukawa Electric Co Ltd:The Junction of led array chip and heat sink base
JPH04245684A (en) * 1991-01-31 1992-09-02 Iwasaki Electric Co Ltd Light emitting diode lamp
JPH10154542A (en) * 1996-11-22 1998-06-09 Nec Corp Electric connector

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2331399B (en) * 1997-11-14 1999-12-01 Prp Optoelectronics Limited High intensity light source
GB2331399A (en) * 1997-11-14 1999-05-19 Prp Optoelectronics Limited High intensity light source
WO2001049164A1 (en) * 1999-12-29 2001-07-12 Keymed (Medical & Industrial Equipment) Ltd Light source for borescopes and endoscopes
US6814699B2 (en) 1999-12-29 2004-11-09 Keymed (Medical & Industrial Equipment) Ltd. Light source for borescopes and endoscopes
GB2370992B (en) * 2000-03-23 2002-11-20 Photo Therapeutics Ltd Therapeutic light source and method
GB2370992A (en) * 2000-03-23 2002-07-17 Photo Therapeutics Ltd A therapeutic light source
GB2360459B (en) * 2000-03-23 2002-08-07 Photo Therapeutics Ltd Therapeutic light source and method
WO2002005357A1 (en) * 2000-07-10 2002-01-17 Osram Opto Semiconductors Gmbh Led module, method for producing the same and the use thereof
US6860621B2 (en) 2000-07-10 2005-03-01 Osram Opto Semiconductors Gmbh LED module and methods for producing and using the module
WO2002005350A1 (en) * 2000-07-12 2002-01-17 Tridonic Optoelectronics Gmbh Method for producing an led light source
WO2002005351A1 (en) * 2000-07-12 2002-01-17 Tridonic Optoelectronics Gmbh Led light source
US8511855B2 (en) 2000-10-16 2013-08-20 Osram Gmbh Configuration of multiple LED module
US8113688B2 (en) 2000-10-16 2012-02-14 Osram Ag Configuration of multiple LED module
EP2337077A1 (en) * 2000-10-16 2011-06-22 OSRAM Opto Semiconductors GmbH LED Module
US6995405B2 (en) 2001-04-23 2006-02-07 Plasma Ireland Limited Illuminator
WO2002086972A1 (en) * 2001-04-23 2002-10-31 Plasma Ireland Limited Illuminator
EP1523041A1 (en) * 2004-12-08 2005-04-13 Jeffrey Chen Light emitting diode assembly having high-performance heat dissipation means
DE102005036275A1 (en) * 2005-08-02 2007-02-08 Berchtold Holding Gmbh surgical light
WO2008141500A1 (en) * 2007-05-18 2008-11-27 Hujun Huang A circuit board for heat dispersion
WO2009082865A1 (en) * 2007-12-30 2009-07-09 Foshan Nationstar Optoelectronics Limited Liability Company Led plane light source for universial illumination
WO2013035024A1 (en) * 2011-09-06 2013-03-14 Koninklijke Philips Electronics N.V. Topology of distributing and connecting leds in a large area matrix
CN103765496A (en) * 2011-09-06 2014-04-30 皇家飞利浦有限公司 Topology of distributing and connecting LEDs in a large area matrix
US9655183B2 (en) 2011-09-06 2017-05-16 Philips Lighting Holding B.V. Topology of distributing and connecting LEDs in a large area matrix

Also Published As

Publication number Publication date
GB9304659D0 (en) 1993-04-28
GB2276032B (en) 1997-04-16

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PCNP Patent ceased through non-payment of renewal fee

Effective date: 20050308