`
`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`
`In re Patent of:
`
`Lebens et al.
`
`U.S. Patent No.:
`
`6,095,661
`
`
`
`Issue Date:
`
`August 1, 2000
`
`Appl. Serial No.:
`
`09/044,559
`
`Filing Date:
`
`March 19, 1998
`
`Title:
`
`METHOD AND APPARATUS FOR AN L.E.D.
`
`FLASHLIGHT
`
`
`PETITION FOR INTER PARTES REVIEW OF UNITED STATES PATENT
`NO. 6,095,661 PURSUANT TO 35 U.S.C. §§ 311–319, 37 C.F.R. § 42
`
`Exhibit LG-1001
`U.S. Patent No. 6,095,661 to Lebens, et al. (“’661 Patent”)
`
`
`

`

`Ulllted States Patent [19]
`Lebens et al.
`
`US006095661A
`[11] Patent Number:
`[45] Date of Patent:
`
`6,095,661
`Aug. 1, 2000
`
`[54] METHOD AND APPARATUS FOR AN L,E_I)_
`
`5,424,927
`
`6/1995 Schaller et al. ....................... .. 362/157
`
`FLASHLIGHT
`
`[75] Inventors: Gary A. Lebens, Chaska; Charles T.
`?ounl’ Mgmeltotilja? challlllesfli/l'.
`emalre’ pp 6 a 6y’ a O
`Inn’
`[73] Assignee: PPT Vision, Inc., Eden Prairie, Minn.
`
`[21] Appl. No.: 09/044,559
`[22] Filed:
`Mar. 19, 1998
`
`7
`[51] Int. Cl. ................................................... .. H04B 10/04
`U-S. Cl. ........................ ..
`362/249; 362/157; 362/208; 362/800; 315/224;
`315/307; 315/291; 315/312; 315/360; 315/362
`[58] Field Of Search ................................... .. 362/157, 183,
`362/159> 184> 208> 800> 249; 315/224>
`307> 291> 312> 360> 362
`_
`References Clted
`U_S_ PATENT DOCUMENTS
`
`[56]
`
`4,208,579
`432903095
`
`6/1980 Scrivo ................................... .. 250/227
`9/1981 schmldt
`362/191
`
`4j592:147
`
`6/1986 Herman
`
`4’820’229
`4,831,504
`
`4/1989 spraggins _ _ _ _ _ _ _ _ _ _ _ _ _
`5/1989 Nishizawa et a1_ __
`
`4,893,815
`1/1990 Rowan _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
`4,962,347 10/1990 Burroughs et al. ..
`4,964,023 10/1990 NiShiZaWa et al- -
`479787857 12/1990 Juengel ~~~~~~~~~~~~~~ -~
`530153918
`5/1991 Copeland '
`5’O65’035 11/1991 Juengel
`
`5,179,335
`
`1/1993 Nor . . . . . . . . . .
`
`~~~~ " 33/366
`
`_ _ _ _ __ 446/26
`__ 362/100
`
`_ _ _ _ __ 273/84
`320/48
`362/100
`-~ 250/551
`"" " 315/76
`" 250/551
`
`. . . . .. 320/21
`
`5,838,247 11/1998 Bladowski . . . . .
`. . . .. 340/815
`5,890,794
`4/1999 Abtahi et al. ......................... .. 362/184
`Primary Examiner_sandra O.Shea
`Assistant Examiner—Bertrand Zeade
`Attorney, Agent,
`or Firm—SchWegman, Lundberg,
`Woessner & Kluth’ PA‘
`[57]
`ABSTRACT
`
`Improved method and apparatus for hand-held portable
`illumination. A ?ashlight and corresponding method are
`described. The ?ashli ht includes a housin , a luralit of
`LEDs’ and an electric 51 Circuit that selectivelgy apghespozver
`from the
`Voltage Source to the
`units, wherein the
`?ashlight is suitable for handheld portable operation by a
`user. In one embodiment, the ?rst electrical circuit further
`includes a Control Circuit for maintaining a predetermined
`light output level of the LED units as a charge on a battery
`varies. In another embodiment, the control circuit maintains
`an average predetermined light output level of the LED units
`as the charge on the battery cell varies by changing a pulse
`Width or frequency as the charge on the battery cell varies to
`maintain a given average light output. Another aspect pro
`Vides an illumination Source that includes a 1ight_emimng
`diode (LED) housing including one or more LEDs, and a
`control circuit that selectively applies power 'from a source
`of electric povver to the LEDs, the control circuit substan
`
`tially maintaining a light output characteristic of the LEDs
`as a voltage of the voltage source varies over a range that
`
`Would otherwise vary the light output characteristic. Still
`another aspect provides an illumination source including a
`light-emitting diode (LED) housing including one or more
`LEDs; and a control circuit that selectively applies poWer
`from a source of electric poWer to the LEDs, thus maintain
`ing or controlling a light output color spectrum of the LEDs.
`
`5,279,513
`5,299,227
`
`446/219
`1/1994 Connelly ..
`3/1994 Rose .......................................... .. 375/1
`
`52 Claims, 11 Drawing Sheets
`
`xPULSE SYNC. SIGNAL—
`
`POWER SUPPLY
`AND CONTROL
`
`FEEDBACK
`
`Exhibit LG-1001 Page 1
`
`

`

`US. Patent
`
`Aug. 1, 2000
`
`Sheet 1 0f 11
`
`6,095,661
`
`._o~_._.zoooz<
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`EmnSmE26;
`
`Exhibit LG—1001 Page 2
`
`Exhibit LG-1001 Page 2
`
`

`

`US. Patent
`
`Aug. 1, 2000
`
`Sheet 2 0f 11
`
`6,095,661
`
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`Exhibit LG—1001 Page 3
`
`Exhibit LG-1001 Page 3
`
`
`
`

`

`US. Patent
`
`Aug. 1, 2000
`
`Sheet 3 0f 11
`
`6,095,661
`
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`Exhibit LG—1001 Page 4
`
`Exhibit LG-1001 Page 4
`
`
`
`

`

`U.S. Patent
`
`Aug. 1,2000
`
`Sheet 4 0f 11
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`6,095,661
`
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`Exhibit LG-1001 Page 5
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`U.S. Patent
`
`Aug. 1,2000
`
`Sheet 5 0f 11
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`6,095,661
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`Exhibit LG-1001 Page 6
`
`

`

`U.S. Patent
`
`Aug. 1,2000
`
`Sheet 6 0f 11
`
`6,095,661
`
`PHOTON ENERGY (eV)
`
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`Exhibit LG-1001 Page 7
`
`

`

`U.S. Patent
`
`Aug. 1,2000
`
`Sheet 7 0f 11
`
`6,095,661
`
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`Exhibit LG-1001 Page 8
`
`

`

`U.S. Patent
`
`Aug. 1,2000
`
`Sheet 8 0f 11
`
`6,095,661
`
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`Exhibit LG-1001 Page 9
`
`

`

`U.S. Patent
`
`Aug. 1,2000
`
`Sheet 9 0f 11
`
`6,095,661
`
`
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`
`3.55
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`
`PHOTON ENERGY (eV)
`
`Exhibit LG-1001 Page 10
`
`

`

`US. Patent
`
`Aug. 1, 2000
`
`Sheet 10 0f 11
`
`6,095,661
`
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`Exhibit LG—1001 Page 11
`
`Exhibit LG-1001 Page 11
`
`
`
`

`

`US. Patent
`
`Aug. 1, 2000
`
`Sheet 11 0f 11
`
`6,095,661
`
`ZIFKIa.
`
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`Exhibit LG—1001 Page 12
`
`Exhibit LG-1001 Page 12
`
`
`

`

`1
`METHOD AND APPARATUS FOR AN L.E.D.
`FLASHLIGHT
`
`FIELD OF THE INVENTION
`
`This invention relates to the ?eld of lighting, and more
`speci?cally to a method and apparatus of controlling and
`poWering a solid-state light source such as a light-emitting
`diode or LED, for a portable battery-poWered ?ashlight.
`
`BACKGROUND OF THE INVENTION
`
`1O
`
`There is a Widespread need for hand-held ?ashlights and
`lanterns. One common ?ashlight includes a tWo-cell battery
`for poWer, an incandescent lamp to emit light, and a simple
`single-pole sWitch to connect and disconnect the battery to
`the lamp. Other ?ashlights use other numbers of battery cells
`in order to provide a voltage suitable for various particular
`conditions. Lanterns often use a ?uorescent tube to emit
`light. Certain keychain fobs use a pair of hearing-aid cells
`and a red-light light-emitting diode (LED) in order to
`provide short-range lighting such as might be -needed to ?nd
`a keyhole in the dark.
`Battery technology is such that as electrical poWer is
`WithdraWn from a battery cell, the voltage available across
`a given current load Will decrease. This decreased available
`voltage across the given load causes reduced light output,
`gradually dimming the light as the battery charge depletes.
`Further, LEDs have voltage, current, and poWer param
`eters that must be controlled in order to maximize device
`life. Commonly, a current-limiting resistor is placed in series
`With an LED in order that only a portion of the voltage drop
`from the battery is across the LED and the rest of the voltage
`drop is across the resistor. This voltage drop and correspond
`ing poWer loss in the resistor is dissipated as Waste heat,
`Which is inef?cient for a ?ashlight Which should be designed
`to emit light.
`In addition, it is aWkWard or difficult to determine the
`amount of remaining charge in a battery cell, generally
`requiring removal of the battery from the ?ashlight in order
`to measure the remaining charge. In addition, the cost of a
`separate measurement device can be a negative for this
`market. Some battery cells today include a built-in liquid
`crystal indicator for the charge in the cell, but such a solution
`requires a separate measurement device/indicator for each
`battery, and requires removal of the battery from the ?ash
`light in order to perform the measurement and observe the
`indication of remaining poWer.
`
`SUMMARY OF THE INVENTION
`The present invention provides a method and apparatus
`for an LED. ?ashlight or other LED illumination source. In
`one embodiment, a ?ashlight is described. The ?ashlight
`includes a ?ashlight housing suitable for receiving therein
`and/or mounting thereon at least one DC voltage source such
`as a battery. The ?ashlight also includes a light-emitting
`diode (LED) housing connected to the ?ashlight housing,
`the LED housing including a ?rst plurality of LED units that
`each emit light and have a re?ector for collimating the
`emitted light forWardly therefrom generally along an LED
`optical axis, the ?rst plurality of LED units including at least
`seven individual LED units. The ?ashlight also includes a
`?rst electrical circuit that selectively applies poWer from the
`DC voltage source to the LED units, Wherein the ?ashlight
`is of such compact siZe and loW Weight as to be suitable for
`single-handed portable operation by a user, the ?ashlight
`further having a purpose of providing general-purpose illu
`mination.
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`6,095,661
`
`2
`In one embodiment, the LED optical axes of the ?rst
`plurality of LED units in the ?ashlight are substantially
`parallel to one another. In one such embodiment, the ?ash
`light further includes a second plurality of LED units that
`each emit light and have a re?ector for collimating the
`emitted light forWardly therefrom generally along an LED
`optical axis, Wherein the LED optical axes of the second
`plurality of LED units converge or diverge from one another
`forWardly from the housing.
`In another embodiment, an optical spread angle of the ?rst
`plurality of LED units in the ?ashlight are substantially
`equal to one another. In one such embodiment, the ?ashlight
`further includes a second plurality of LED units that each
`emit light and have a re?ector for collimating the emitted
`light forWardly therefrom generally along an LED optical
`axis, Wherein an optical spread angle of the second plurality
`of LED units are substantially equal to one another, and
`different than the optical spread angle of the ?rst plurality of
`LED units.
`In yet another embodiment, the LED units are connected
`in a parallel-series con?guration With at least tWo LED units
`coupled in parallel to one another and in series With at least
`one other LED unit, and the DC voltage source includes at
`least three battery cells connected in series.
`In still another embodiment, the ?rst electrical circuit
`further includes a control circuit for maintaining a prede
`termined light output level of the LED units as a charge on
`the battery cell varies. In one such embodiment, the control
`circuit maintains an average predetermined light output level
`of the LED units as the charge on the battery cell varies by
`increasing a pulse Width or a pulse frequency as the charge
`on the battery cell decreases. In another such embodiment,
`the control circuit maintains an average predetermined light
`output level of the LED units by measuring a battery voltage
`and adjusting a pulse Width or a pulse frequency or both to
`maintain the average light output at the predetermined level.
`In still another such embodiment, the control circuit main
`tains an average predetermined light output level of the LED
`units by measuring an average light output and adjusting a
`pulse Width or a pulse frequency or both to maintain the
`measured average light output at the predetermined level.
`Another aspect of the present invention provides a ?ash
`light including: (a) a ?ashlight housing, the housing being
`suitable for at least one of receiving therein and mounting
`thereon at least one DC voltage source that includes at least
`one battery cell; (b) a light-emitting diode (LED) housing
`connected to the ?ashlight housing, the LED housing includ
`ing one or more ?rst LED units that each emit light and have
`a re?ector for collimating the emitted light forWardly there
`from generally along an LED optical axis; and (c) a ?rst
`electrical circuit that selectively applies poWer from the DC
`voltage source to the LED units, the ?rst electrical circuit
`further including a control circuit for maintaining a prede
`termined light output level of the LED units as a charge on
`the battery cell varies; Wherein the ?ashlight is of such
`compact siZe and loW Weight as to be suitable for single
`handed portable operation by a user, the ?ashlight further
`having a purpose of providing general-purpose illumination.
`In one such embodiment, the ?rst LED units being a ?rst
`plurality of LED units, Wherein the LED optical axes of the
`?rst plurality of LED units are substantially parallel to one
`another. In another such embodiment, the ?ashlight further
`includes a second plurality of LED units that each emit light
`and have a re?ector for collimating the emitted light for
`Wardly therefrom generally along an LED optical axis,
`Wherein the LED optical axes of the second plurality of LED
`units converge or diverge from one another forWardly from
`the housing.
`
`Exhibit LG-1001 Page 13
`
`

`

`6,095,661
`
`3
`In another such embodiment, the ?rst LED units are a ?rst
`plurality of LED units, Wherein an optical spread angle of
`the ?rst plurality of LED units are substantially equal to one
`another. In yet another such embodiment, the ?ashlight
`further includes a second plurality of LED units that each
`emit light and have a re?ector for collimating the emitted
`light forWardly therefrom generally along an LED optical
`axis, Wherein an optical spread angle of the second plurality
`of LED units are substantially equal to one another, and
`different than the optical spread angle of the ?rst plurality of
`LED units.
`Another aspect of the present invention provides a method
`of providing general-purpose illumination of such compact
`siZe and loW Weight as to be suitable for single-handed
`portable operation by a user, including the steps of: (a)
`providing one or more ?rst LED units that each emit light
`and have a re?ector for collimating the emitted light for
`Wardly therefrom generally along an LED optical axis; (b)
`selectively applying poWer from a DC voltage source to the
`LED units; and (c) maintaining a predetermined light output
`level of the LED units as a charge on the battery cell varies
`by controlling the step
`In one embodiment, the step of maintaining maintains an
`average predetermined light output level of the LED units as
`the charge on the battery cell, varies by increasing a pulse
`energy or a pulse frequency as the charge on the battery cell
`decreases. In another embodiment, the step of maintaining
`maintains an average predetermined light output level of the
`LED units by measuring a battery voltage and adjusting a
`pulse Width or a pulse frequency or both to maintain the
`average light output at the predetermined level. In still
`another embodiment, the step of maintaining maintains an
`average predetermined light output level of the LED units by
`measuring a light output and adjusting a pulse energy or a
`pulse frequency or both to maintain an average light output
`at the predetermined level.
`Yet another aspect of the present invention provides an
`illumination source, that includes (a) a light-emitting diode
`(LED) housing including one or more LEDs; and (b) a
`control circuit that selectively applies poWer from a source
`of electric poWer to the LEDs, the control circuit substan
`tially maintaining a light output characteristic of the LEDs
`as a voltage of the voltage source varies over a range that
`Would otherWise vary the light output characteristic. In one
`such embodiment, the light output characteristic that is
`maintained is light output intensity. In another such
`embodiment, the control circuit maintains the light output
`intensity of the LED units as the voltage of the DC voltage
`source varies by increasing a pulse Width, a pulse energy, or
`a pulse frequency as the voltage of the DC voltage source
`decreases. In another such embodiment, the control circuit
`maintains an average predetermined light output level of the
`LED units by measuring a voltage and adjusting a pulse
`energy or a pulse frequency or both to maintain the average
`light output at the predetermined level. In yet another such
`embodiment, the control circuit maintains an average pre
`determined light output level of the LED units by measuring
`an average light output and adjusting a pulse Width or a pulse
`frequency or both to maintain the measured average light
`output at the predetermined level.
`Another aspect of the present invention provides a
`battery-poWered portable ?ashlight (100) including: a casing
`(110) suitable to hold a battery; one or more light-emitting
`devices (LEDs) (150) mounted to the casing; a sWitch (140)
`mounted to the casing; and a control circuit (130) coupled to
`the battery, the LEDs, and the sWitch, Wherein the control
`circuit drives the LEDs With electrical pulses at a frequency
`
`10
`
`15
`
`25
`
`35
`
`45
`
`55
`
`65
`
`4
`high enough that light produced by the LEDs has an appear
`ance to a human user of being continuous rather than pulsed,
`and Wherein the LEDs have proportion of on-time that
`increases as remaining battery poWer decreases. One such
`embodiment further includes a feedback circuit that controls
`the pulses so that light intensity produced by the LEDs, as
`perceived by the human user, is substantially constant across
`a greater range of battery poWer or voltage than a corre
`sponding range for Which light intensity is equally constant
`Without the feedback circuit. In one such embodiment, the
`feedback circuit measures a light output of the LEDs.
`Another such embodiment further includes a battery
`voltage-measuring circuit coupled to the control circuit.
`Yet another aspect of the present invention provides a
`method for driving battery-poWered portable ?ashlight (100)
`having a casing (110), a DC poWer source mounted to the
`casing, one or more solid-state light-emitting device (LEDs)
`(150) mounted to the casing, the method including the steps
`of: receiving input from a user; and based on the received
`input, generating a series of pulses to drive the LEDs such
`that the LEDs have proportion of on-time that increases as
`remaining battery poWer decreases.
`Still another aspect of the present invention provides an
`illumination source including (a) a light-emitting diode
`(LED) housing including one or more LEDs; and (b) a
`control circuit that selectively applies poWer from a source
`of electric poWer to the one or more LEDs, the control circuit
`maintaining a predetermined light output color spectrum of
`the one or more LEDs as a voltage of the source of electric
`poWer varies. In one such embodiment, the one or more
`LEDs comprise one or more LEDs having a ?rst character
`istic color spectrum output and one or more LEDs having a
`second characteristic color spectrum output, the ?rst char
`acteristic color spectrum output different from the second
`characteristic color spectrum output, and the control circuit
`controls a pulse characteristic in order to control the pro
`portion of light output having the ?rst characteristic color
`spectrum output to that having the second characteristic
`color spectrum output. In another such embodiment, the one
`or more LEDs comprise one or more LEDs having a
`characteristic color spectrum output that varies based on
`applied current, and the control circuit controls a pulse
`current in order to control the characteristic color spectrum
`output.
`Yet another aspect of the present invention provides an
`illumination source that includes (a) a light-emitting diode
`(LED) housing including one or more LEDs; and (b) a
`control circuit that selectively applies poWer from a source
`of electric poWer to the LEDs to adjust a light output color
`spectrum of the one or more LEDs.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 shoWs one embodiment of the present invention, a
`schematic representation of a handheld LED ?ashlight 100.
`FIG. 2 is a circuit block diagram of an LED ?ashlight
`circuit 200, Which circuit is used in some embodiments of
`LED ?ashlight 100 of FIG. 1 or LED light source in
`camcorder 500 of FIG. 5 or other devices such as machine
`vision systems.
`FIG. 3 a circuit block diagram of an LED ?ashlight circuit
`300, Which circuit is used in some embodiments of LED
`?ashlight 100 of FIG. 1 or LED light source in camcorder
`500 of FIG. 5 or other devices such as machine-vision
`systems.
`FIG. 4 a circuit block diagram of an LED ?ashlight circuit
`400, Which circuit is used in some embodiments of LED
`
`Exhibit LG-1001 Page 14
`
`

`

`6,095,661
`
`5
`?ashlight 100 of FIG. 1 or LED light source in camcorder
`500 of FIG. 5 or other devices such as machine-vision
`systems.
`FIG. 5 is a diagram showing a controlled LED light
`source is integrated into a handheld camcorder 500.
`FIG. 6 is a graph of color spectrum versus current for an
`LED to be used in one embodiment of the present invention
`FIG. 7 is circuit block diagram of an LED illumination
`device circuit 700, Which circuit is used in some embodi
`ments of LED ?ashlight 100 of FIG. 1 or LED light source
`in camcorder 500 of FIG. 5 or other devices such as
`machine-vision systems.
`FIG. 8 is circuit block diagram of an LED illumination
`device circuit 700 that uses a current mirror.
`FIG. 9 is a graph of color spectrum (photoluminescence)
`versus temperature for an LED to be used in one embodi
`ment of the present invention.
`FIG. 10 is circuit block diagram of a machine vision
`system using an LED illumination device according to the
`present invention.
`FIG. 11 is circuit block diagram of an LED illumination
`device according to the present invention.
`
`10
`
`15
`
`DESCRIPTION OF PREFERRED
`EMBODIMENTS
`In the folloWing de tailed description of the preferred
`embodiments, reference is made to the accompanying draW
`ings that form a part hereof and in Which are shoWn by Way
`of illustration speci?c embodiments in Which the invention
`may be practiced. It is understood that o the r embodiments
`may be utiliZed and structural changes may be made Without
`departing from the scope of the present invention.
`The present invention takes advantage of the ef?ciency of
`high-intensity, light-emitting diodes (LEDs) in the visible
`spectrum and/or infra-red (IR) or ultra-violet (UV), arranged
`in various patterns, the loW-voltage properties of CMOS
`integrated circuits and components, and the ef?ciency
`derived from sWitching the current to and limiting the
`duration of current to the LEDs to project light ef?ciently
`and With constant brightness even as the battery supply
`voltage decays over time. The invention takes advantage of
`the dynamic impedance of the LEDs Which causes the
`voltage across the LED to rise rapidly relative to the current
`?oW through the LED to limit the initial current ?oW to the
`LED, When battery voltage is highest, to prevent Wire bond
`heating from causing premature failure of the LEDs. The
`present invention controls the current ?oW duration (pulse
`Width) to limit poWer dissipation in the LEDs during the
`LEDs’ on state, and increasing the pulse Width as the battery
`voltage decreases over time to maintain substantially con
`stant perceived or average LED intensity over the course of
`the battery’s life. The invention controls the sWitching
`frequency of the pulse Width to further control the LED
`intensity and poWer dissipation While maintaining a constant
`light output from the LEDs as perceived or visible to the
`human eye, or a light-sensing device, e.g., camera, night
`vision scope, CMOS and CCD sensor and piXel arrays. The
`present invention provides a compact, portable light source,
`preferably siZed to be readily hand-held, for illuminating an
`object, several objects, or areas for human use and/or
`machine operation. In one embodiment, the invention mea
`sures battery voltage and in turn regulates the LED intensity.
`In another embodiment, the present invention uses a light
`sensing device such as a light-sensing transistor or light
`detecting diode (LDD) in proximity to the output LED(s) to
`measure the average brightness and further regulate the
`LEDs’ output.
`
`25
`
`35
`
`45
`
`55
`
`65
`
`6
`Another embodiment of the present invention provides
`operator-selectable control of the pulse frequency and/or the
`pulse Width to provide a reduced apparent brightness in
`order to increase battery life in situations When maXimum
`brightness is not required. In one such pulse-frequency
`embodiment, the apparent (visible) pulse frequency Would
`provide a stroboscope effect for safety or entertainment. In
`this embodiment, the visibly interrupted or pulsed pulse
`train may include repetitive pulses or a coded sequence as in
`Morse code “SOS” or a predetermined passWord or security
`string of pulses that may then be used as a key or identi?er.
`A further re?nement of this embodiment Would provide the
`user With a method for strobing out a message. It is under
`stood that What appears to be a single visible pulse may
`actually include a high-frequency series of pulses in order to
`increase the apparent brightness of a single pulse While also
`protecting the LEDs from excessive poWer dissipation. In
`yet another pulse-frequency embodiment of the invention, a
`variable or adjustable constant sequence pulse train is estab
`lished for the accurate measurement of the velocity or
`frequency of an object in motion or vibration.
`Another embodiment of the present invention uses vari
`ous colored LEDs for specialiZed purposes. In one such
`embodiment, long-Wavelength LEDs, 660 nm or longer, are
`used to provide underWater divers or aquarium enthusiasts a
`light source for observing undersea life at night Without
`adversely affecting the nocturnal activities of such Wildlife.
`This functionality is also useful for tropical aquarium oWn
`ers Who also Wish to observe the nocturnal activities of the
`occupants of their aquariums. In another such embodiment,
`short-Wavelength blue LEDs are used With a UV ?lter to
`vieW ?uorescing materials, including but not limited to:
`taggants, stamps, security codes and security seals. As UV
`LEDs become readily available (such as those announced as
`made by IBM Corporation in the Mar. 9, 1998 issue of
`Electronic Engineering Times, page 39), these could be used
`in place of the blue LEDs. In other embodiments, a suitable
`LED normally emitting in the blue spectrum, for eXample
`made from GaN (gallium nitride) or InGaN (indium gallium
`nitride), is pulsed by pulses of suf?ciently high current to
`blue-shift the output and suf?ciently short duration to not
`destroy the LED in order to maintain a constant light
`intensity While shifting the color spectrum from blue to
`ultraviolet. Other embodiments include IR LEDs for mili
`tary or police use to enhance the usefulness of night-vision
`equipment and for friend-or-foe identi?cation, multiple
`color LEDs to produce a White light source, and combina
`tions of colored LEDs to enhance the ability of color-blind
`individuals to perceive colors. Other uses include LEDs
`chosen for use in photographic darkrooms Wherein the LED
`Wavelength is chosen to prevent undesired eXposure of
`light-sensitive materials.
`Another embodiment of the present invention uses LEDs
`of various “vieWing” angles to achieve Wide-angle vieWing
`versus narroW-angle, long-range vieWing and combinations
`thereof. A further re?nement of this embodiment utiliZes a
`Fresnel lens (or other lens or re?ector arrangement) to
`provide a focusable light source. Another embodiment uses
`polariZers to reduce specular re?ections for enhanced vieW
`ing or for use in machine-vision applications. Another
`embodiment utiliZes quickly and easily pluggable/
`replaceable LED arrays or heads of various shapes, colors,
`and/or vieWing angles for different applications.
`In yet another embodiment, the light output is momen
`tarily interrupted repetitively, or strobed, to indicate loW
`battery condition With some estimation of time to battery
`failure, e.g., the number of pulses could indicate the esti
`
`Exhibit LG-1001 Page 15
`
`

`

`6,095,661
`
`7
`mated number of minutes of battery time. As the estimation
`of time to battery failure changes, the repetition rate is varied
`to indicate impending battery failure. It is understood that
`this operational mode is easily distinguished from other
`operational modes by the duration of on time versus off time.
`In strobe mode, loW battery condition is indicated by drop
`ping pulses; e.g., every fourth output pulse is dropped, or
`three of four pulses is dropped creating an easily distin
`guishable variance in visible output of the invention.
`In another embodiment of the invention, a sWitch is
`utiliZed to control the functions (and/or brightness) of the
`invention. A variance of this embodiment uses a thumb
`Wheel, or rotary sWitch to vary the sWitching characteristics
`to produce a variable light output.
`In another embodiment, a programmable microprocessor
`is utiliZed to provide control functionality.
`FIG. 1 shoWs one embodiment of the present invention (a
`schematic representation of a LED ?ashlight 100) having a
`case 110, a battery 120 or other portable DC poWer supply,
`a poWer supply and control circuit 130, a sWitch circuit 140,
`a plurality of LEDs 150, and optionally a feedback circuit
`160.
`In various embodiments of the present invention, feed
`back circuit 160 (and similarly the other feedback circuits
`described herein) controls pulse Width and/or frequency as a
`function of parameters such as battery voltage, LED light
`output intensity, poWer dissipation or device temperature, or
`LED color spectrum output.
`Case 110 is any convenient siZe and shape, and is typi
`cally designed to hold the battery, provide a suitable grip to
`be handheld, and provide a housing for the circuitry and
`LEDs. In one embodiment, battery 120 includes one or more
`cells Which can be any suitable technology such as alkaline
`dry cells or rechargeable cells. Alternatively, other portable
`DC electrical poWer sources can be used as desired in place
`of battery 120. PoWer supply and control circuit (PSCC) 130
`responds to sWitch circuit to apply electrical poWer from
`battery 120 to LEDs 150, controlled in order to prevent
`overloading and premature destruction of LEDs 150 While
`minimiZing poWer dissipation Within PSCC 130, thus maxi
`miZing battery life, providing the desired accuracy or level
`of the amount of light emitted at different battery voltages or
`other environmental conditions that Would otherWise vary
`the light output. SWitch circuit 140 alloWs the user to control
`various ?ashlight functions such as, for example, on/off,
`setting light level, setting light color, setting pulse or strobe
`frequency, and checking battery voltage or remaining poWer.
`In one embodiment, PSCC 130 provides a pulse train, in
`Which pulse frequency, pulse Width, or pulse shape/height,
`and/or the number of LEDs that are driven, is controlled in
`order to provide a relatively constant light output level even
`as battery voltage declines and poWer is drained. In one
`embodiment, feedback 160 measures the light output of
`LEDs 150 (e.g., using a photo diode or other suitable light
`detecting device) and provides a signal that alloWs PSCC
`130 to adjust the light output to a desired level (typically
`providing a constant light output even as battery voltage
`declines as poWer is drained). In one such embodiment, the
`Width of each pulse is adjusted to keep a con