United States Patent (19)
`Jiang et al.
`
`USOO5946 121A
`Patent Number:
`11
`(45) Date of Patent:
`
`5,946,121
`Aug. 31, 1999
`
`54) IRDA DATA LINK WITH VCSEL LIGHT
`SOURCE
`
`75 Inventors: Wenbin Jiang, Phoenix; Michael S.
`Lebby, Apache Junction, both of Ariz.
`
`73 Assignee: Motorola, Inc., Schaumburg, Ill.
`
`5,138,489 8/1992 Paek .......................................... 359/29
`5,483,511
`1/1996 Jewell et al. ............................ 369/112
`5,526,182 6/1996 Jewell et al. ............................ 359/455
`5,557,693 9/1996 Stevens et al. ......................... 359/173
`5,652,813 7/1997 Wilson ...................................... 385/24
`5,668,826 9/1997 Bezinge et al. ......................... 359/18O
`5,761,364 6/1998 Knapp et al. ............................. 385/43
`
`21 Appl. No.: 08/674,377
`22 Filed:
`Jul. 2, 1996
`(51) Int. Cl." ..................................................... H04B 10/00
`52 U.S. Cl. .......................... 359/172; 35.9/173; 359/180;
`359/29; 359/455; 369/112; 385/24; S.
`
`Primary Examiner Jeffrey A. Hofsass
`ASSistant Examiner John Tweel, Jr.
`Attorney, Agent, or Firm Eugene A. Parsons; William E.
`Koch
`57
`
`ABSTRACT
`
`58 Field of Search ..................................... 359/172, 173, A light Source for use in an infra-red data association data
`359/152, 180, 124, 29, 215,455; 385/88,
`link device including a vertical cavity Surface emitting laser
`24, 33,43; 369/112
`for emitting a beam of light along a path, and a diverger
`References Cited
`positioned in the path for diverging the emitted beam of
`light.
`
`56)
`
`U.S. PATENT DOCUMENTS
`5,073,041 12/1991 Rastani ...................................... 385/33
`
`18 Claims, 1 Drawing Sheet
`
`
`
`Exhibit 1014
`Page 1 of 4
`
`

`

`U.S. Patent
`US. Patent
`
`Aug. 31, 1999
`Aug. 31, 1999
`
`5,946,121
`5,946,121
`
`
`
`
`
`Exhibit 1014
`
`Page 2 of 4
`
`Exhibit 1014
`Page 2 of 4
`
`

`

`1
`IRDA DATA LINK WITH WCSEL LIGHT
`SOURCE
`
`5,946,121
`
`2
`several views, attention is first directed to FIG. 1 which
`illustrates a simplified diagram of a data link generally
`designated 10. Data link 10 includes a light transmitting
`device 12 and a light receiving device 13 coupled by a
`transmission medium Such as an optical fiber 14. Light is
`emitted from light transmitting device 12 along a path into
`optical fiber 14 and thence toward light receiving device 13.
`In most instances, these devices are transceivers capable of
`both receiving and Sending light signals thereby providing
`two way communication. Specifically, these devices are
`typically infra-red data association (IrDA) data link devices
`that work in a free Space medium and which utilize a light
`Source for generating light signals. In the ensuing descrip
`tion the light source for a data link device will be described.
`Turning now to FIG. 2, a perspective View illustrating a
`light Source generally designated 20 is illustrated. Light
`Source 20 includes a vertical cavity Surface emitting laser
`(VCSEL) 22 which generates the light signal in the form of
`a laser beam designated 23. The use of a VCSEL greatly
`reduces power consumption while enhancing the ability to
`increase transmission Speeds. This will be discussed in
`greater detail presently. VCSEL 22, in this embodiment, is
`carried by a conventional TO-head 24 having a base 25 and
`sidewalls 27. Further description of To-head 24 is omitted as
`it is well known in the art. VCSEL 22 is mounted on base
`25 and enclosed by sidewall 27.
`VCSELS typically generate a beam of light having a very
`Small divergence angle which is unsuitable as the light
`Signals for data linkS. A divergence device is used to diverge
`the emitted light so that it is readily receivable by the
`downstream element Such as a free Space medium. The
`diverger is positioned in the path of the beam, diverging the
`beam of light as much as 45 degreeS. Lesser divergence is
`readily obtainable.
`A lid 28 is positioned on sidewalls 27 enclosing VCSEL
`22. VCSEL22 is oriented to emit a beam of light (laser beam
`23) along a path generally vertically upward, through lid 28
`which is positioned in the path of the beam of light. Laser
`beams, as emitted by VCSEL22, provide sufficient light for
`Signals, but, as discussed previously, are much too narrowly
`collimated to cover the area necessary. Light Source 20
`includes a diverger to increase the divergence angle of the
`beam of light. In this embodiment, the diverger is a lens 30
`carried by lid 28. Lens 30 can actually be molded as a
`portion of lid 28. As illustrated, lens 30 is a negative lens.
`Specifically, lens 30 is a concave lens. As laser beam 23
`passes through lens 30, its divergence angle is increased as
`to as much as 45 degrees to provide a light beam 29 having
`the desired divergence angle. While the diverger is illus
`trated as a concave or negative lens, a holographic-unit
`diffuser can also be employed as lid 28. A holographic
`diffuser will adequately diverge the beam of light as
`required. It should also be noted here that packaging other
`than a TO-head can be employed for housing VCSEL22 and
`carrying a diverger power increasing the divergence angle of
`the beam of light.
`Referring now to FIG. 3, light source 20 is illustrated with
`an alternate diverger. In this specific instance, the diverger is
`a positive lens 32 positioned extremely close to VCSEL22,
`resulting in an over-convergence of the light beam. An
`over-convergence of the light beam is as effective as a
`divergence of the beam, resulting in an increase in the
`divergence angle. AS laser beam 23 passes through positive
`lens 32, it is converged to a point 33, after which the beam
`over converges with the net result of a beam 34 having an
`increased divergence angle.
`By employing a VCSEL as a light Source in a data link
`device, energy consumption is greatly reduced. This is
`
`5
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`25
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`35
`
`15
`
`FIELD OF THE INVENTION
`This invention relates to photonic devices employing a
`light Source. More particularly, the present invention per
`tains to light Sources for IrDA data linkS.
`BACKGROUND OF THE INVENTION
`In many electronic devices great amounts of data need to
`be transmitted, Such as between a computer and peripheral
`devices. A very efficient means of transmitting data is by
`using photonic devices. Currently, infra-red data association
`(IrDA) data link devices are used, generally in the form of
`transceivers. The transceivers employ light emitting diodes
`(LED) as the light generating Source. These devices are
`highly effective, as an LED will generate Sufficient light over
`a Sufficiently large area to be easily received by a transmis
`Sion medium Such as an optical fiber.
`While using an LED as a light source is effective, an LED
`is not energy efficient, requiring Substantial current for
`operation. Large power consumption is highly undesirable
`for portable applications which are becoming increasingly
`more prevalent. Typically, an LED requires approximately
`250 mA pulsed at 30 degree viewing angle. Furthermore, as
`data becomes more complex and therefore grows in size
`correspondingly, higher transmissions Speeds are required.
`Currently LED devices transmit at approximately 115.2
`kbits/sec.
`It would be highly advantageous, therefore, to remedy the
`foregoing and other deficiencies inherent in the prior art.
`Accordingly, it is an object of the present invention to
`provide a new and improved light Source for a data link
`device.
`Another object of the invention is to provide a new light
`Source for a data link device, capable of higher transmission
`Speeds.
`And another object of the invention is to provide a new
`data link light Source having low power consumption mak
`40
`ing it ideal for portable use.
`SUMMARY OF THE INVENTION
`Briefly, to achieve the desired objects of the instant
`invention in accordance with a preferred embodiment
`thereof, provided is a light Source for use in an infra-red data
`asSociation data link device. The light Source includes a
`Vertical cavity Surface emitting laser for emitting a beam of
`light along a path, and a diverger positioned in the path for
`diverging the emitted beam of light.
`BRIEF DESCRIPTION OF THE DRAWINGS
`The foregoing and further and more Specific objects and
`advantages of the instant invention will become readily
`apparent to those skilled in the art from the following
`detailed description of a preferred embodiment thereof taken
`in conjunction with the drawings, in which:
`FIG. 1 is a simplified diagram of a data link,
`FIG. 2 is an isometric view of a light Source used in an
`IrDA in accordance with the present invention; and
`FIG. 3 is an isometric view of light source of FIG. 2
`having a positive lens.
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`Turning now to the drawings in which like reference
`characters indicate corresponding elements throughout the
`
`45
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`50
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`55
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`60
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`65
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`Exhibit 1014
`Page 3 of 4
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`

`

`5,946,121
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`5
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`15
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`35
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`40
`
`45
`
`3
`eXtremely important for portable applications. AS an
`example, employing a VCSEL in a light Source resulting in
`a 45 degree viewing angle requires approximately 48 mA
`assuming slope efficiency of 0.4 W/A. This is a great
`improvement over the 250 mA pulsed at 30 degree viewing
`angle for a conventional LED. Furthermore, using a VCSEL
`in a light Source can provide data transmission Speeds of 10
`Mbit/sec and 100 Mbits/sec.
`Thus, a new and improved light Source for a data link
`device is provided. Further provided is a new light source for
`a data link device capable of higher transmission Speeds and
`having low power consumption making it ideal for portable
`Sc.
`Various changes and modifications to the embodiments
`herein chosen for purposes of illustration will readily occur
`to those skilled in the art. To the extent that Such modifica
`tions and variations do not depart from the Spirit of the
`invention, they are intended to be included within the Scope
`thereof which is assessed only by a fair interpretation of the
`following claims.
`Having fully described the invention in Such clear and
`concise terms as to enable those skilled in the art to
`understand and practice the same.
`What we claim is:
`1. A photonic data link comprising:
`a free Space data transmitting device including a vertical
`cavity Surface emitting laser for emitting a beam of
`light and a Spacial diverger including a lens positioned
`in the path for diverging the emitted beam of light; and
`a data receiving device Spaced from the data transmitting
`device for receiving transmitted light.
`2. A data link as claimed in claim 1 wherein the lens
`includes a negative lens.
`3. A data link as claimed in claim 2 wherein the negative
`lens further includes a concave lens.
`4. A photonic data link comprising:
`a free Space data transmitting device including a vertical
`cavity Surface emitting laser for emitting a beam of
`light and a Spacial diverger including a holographic
`unit diffuser positioned in the path for diverging the
`emitted beam of light; and
`a data receiving device Spaced from the data transmitting
`device for receiving transmitted light.
`5. A data link as claimed in claim 1 wherein the lens is a
`positive lens positioned in the path proximate the Vertical
`cavity Surface emitting laser to over converge the emitted
`beam of light.
`6. A data link as claimed in claim 1 wherein the VCSEL
`50
`is mounted in a TO-head, the To-head including a lid
`carrying the diverger.
`
`25
`
`4
`7. Alight Source for use in a infra-red data association data
`link device comprising:
`a vertical cavity Surface emitting in free Space laser for
`emitting a beam of light along a path; and
`a spacial diverger including a lens positioned in the path
`for diverging the emitted beam of light.
`8. A light source as claimed in claim 7 wherein the lens
`is a negative lens.
`9. A light source as claimed in claim 8 wherein the
`negative lens includes a concave lens.
`10. A light Source for use in a infra-red data association
`data link device comprising:
`a vertical cavity Surface emitting laser for emitting in free
`Space a beam of light along a path; and
`a spacial diverger including a holographic-unit diffuser
`positioned in the path for diverging the emitted beam of
`light.
`11. A light source as claimed in claim 7 wherein the lens
`is a positive lens positioned along the path to over converge
`the emitted beam of light.
`12. A light source as claimed in claim 7 wherein the
`Vertical cavity Surface emitting laser is mounted in a
`TO-head, the To-head including a lid carrying the diverger.
`13. A light Source for use in an infra-red data association
`data link device comprising:
`a vertical cavity Surface emitting in free Space laser for
`emitting a beam of light along a path; and
`a spacial diverger including a lens positioned in the path
`for diverging the emitted beam of light up to approxi
`mately a 45 degree angle of divergence.
`14. A light source as claimed in claim 13 wherein the lens
`includes a negative lens.
`15. A light Source as claimed in claim 14 wherein the
`negative lens includes a concave lens.
`16. A light Source for use in an infra-red data association
`data link device comprising:
`a vertical cavity Surface emitting laser for emitting in free
`Space a beam of light along a path; and
`a spacial diverger including a holographic-unit diffuser
`positioned in the path for diverging the emitted beam of
`light up to approximately a 45 degree angle of diver
`gence.
`17. A light source as claimed in claim 13 wherein the lens
`includes a positive lens positioned along the path proximate
`the vertical cavity Surface emitting laser, to over converge
`the emitted beam of light.
`18. A light source as claimed in claim 13 wherein the
`Vertical cavity Surface emitting laser is mounted in a
`TO-head, the To-head including a lid carrying the diverger.
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`k
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`k
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`k
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`k
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`k
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`Exhibit 1014
`Page 4 of 4
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