CA2168075A1

CA2168075A1 - Led flashing lantern

Info

Publication number: CA2168075A1
Application number: CA002168075A
Authority: CA
Inventors: James T. Hutchisson; David K. Straub
Original assignee: Dominion Automotive Group Inc
Current assignee: Dominion Automotive Group Inc
Priority date: 1995-01-26
Filing date: 1996-01-25
Publication date: 1996-07-27
Also published as: MX9600391A; US5608290A

Abstract

A flashing lantern (11) capable of emitting light through a 360-degree are using LEDs as a light source is disclosed. The lantern comprises an array of LEDs (15) positioned in a substantially horizontal plane. An inverted conical reflector (19) is positioned above the array of LEDs (15) such that the apex of the reflector is pointed toward the array of LEDs (15). A fresnel-type lens (17) is positioned around the array of LEDs (15) and the conical reflector (19).

Description

p~ n ~ 2 1 6 8 0 7 S

LED FLAS~ING LANI ERN
Field of the Invention This invention relates to fl~ching lanterns and, more particularly, to fl~ching lanterns that incorporate light-Pmitting diodes (LEDs) as a light source.
S Baclcground of the Invention Flashing lanterns include both fl~ching beacons and strobe lights. Flashing beacons typically have inr~ntlescPnt or halogen bulbs as their light source, while strobe lights normally incorporate xenon flash tubes. Strobe lights and fl~shingbeacons are used primarily on moving vehicles, such as materials-h~n~ling vehicles, 10 construction vehicles, m~intpn~nee and utility vehicles, and emergency vehicles.
Strobe lights and fl~ching beacons also have stationary applications, such as on road sign~ling stands and warning signs, on the visual part of alarm systems, and on mining equipment. Strobe lights and fl~ching beacons provide visibility, as well as alert people to potentially dangerous situations.
Operationally, fl~ching lanterns require circuitry that will produce a rapid-rise-time light pulse in order for the lantern to be capable of fl~ching frequently and ly in a given time interval. The flash must also be sufficiently intense to meetthe requirements of the int~n~e~ lighting conditions (full daylight to complete darkness). Further, fl~ching l~llellls must be reliable in harsh weather conditions and, 20 when used on moving objects, fl~chinp lanterns must be vibration re~ict~nt Lastly, it is usually bPnpfiri~l if the light emitted by a fl~shin~ lantern is visible from all sides of the lantern.
Conventional fl~ching lanterns comprise a _ash PIPmPnt or light source, a control circuit, a power source, a base, and a housing. The control circuit produces 216807~

-2-the fast-rise-time pulse that con~lols the application of power to the flash el~mPnt The power source may be either internal to the lantern houcing or external to the lantern hol-c;ng The power le~UilCI-l_ ItS can range from 12 to 48 volts DC. Suitable power sources are car batteries and porLable gencla~o, ~.
S The hol~cingc of fl~ching lanLel.. s may include a lens configured to magnify the light ~ OI-C thereLu-n. For e~--rle, some fl~chir~g IA.~ include a L_s -el type lens. While the direction of light emission through the lens is usually outward in a 360-degree arc, some fl~ching lanterns include diverters that direct emissions along a particular e--. C- on path.
In conventional fl~ching lanterns, the flash el~m~nt or light source is typically an inr~ e~nt bulb or a xenon flash tube. Both types of light sources are the plill~ cause of lantern failures. In particular, in~ Pccpnt bulbs have a tçn~len.;y to burn out due to their wires and fil~m~nt~ becoming brittle with age or weak due to external lantern vibrations. Th_.cr~re, inr~nfl~cc~nt bulbs have a relatively short life.
Repl~c~m~nt of inc~n~esc~nt bulbs normally requires some ~ic~csemhly and, thus, is more ~pensi~e and time conc~lming than desirable. Further, inC~n~escent bulbs utilized in fl~ching beacons are normally not as bright as desired.
There are also many disadvantages to strobe lights. Xenon flash tubes require high 0P-~18 voltage, produce W radiation, and have an ope-~ing life of only 2,000 to 3,000 hours. The high voltage requirements make the design of strobe lights more complicated than desired and can create a safety h~7~rd, due to the possibility of an electrical shock during m~int-on~n~e Lastly, with regard to both fl~ching beacons and strobe lights, neither produce monochroll~lic light. Color filters or lenses are required in order to provide colored light emission. Color filters or lenses decrease light tr~ncmicsion and often fade due to weathering and ultraviolet irr~ tion In recent years, a variety of attempts have been made to use LEDs as a light source in fl~ching beacQl-c At least four major types of LEDs are available, two of which are typically used in visible light devices planar and dome LEDs. Due to their structure, the light produced by LEDs çh~ng~s rapidly in intensity in response to a rapid change in current. LEDs are monochro"~ic and available in a variety of colors.
Thus, using LEDs as a light source ~l;.. ;n~es the need for colored filters or lenses, thereby o~ g light tr~ncmi~;o~ while at the same time el;...;n~ g the problem of lens or color fdter fading LEDs require low power to operate and have a long 35 Ope~ali~lg life--over 100,000 hours for some types.

' . ~PDOC

-3-~ lthollgh the above cl~a~lelialics are adv-q-ntageolls con~ y, early versions of T Fns had low light ~ g energy and l~...;nAn~, which made them difficult to see. LEDs have also been ~iffiallt to utilize in flqching lanterns due to their inh~ structure. More ~pel-ifi~qlly~ since the light emicsiQn path of a n~ch.l~g 5 lantern optima~ly covers an arc of 360 degrees, it is desirable to use an omnidir~ ~r-' light source placed in the center of the lantern. Bulbs are omnidil~ n~l; LEDs are not. In this regard, LEDs are typically created using flat se niconductor materials, reslllting in a light ~miC~ion path that radiates outwardly from a _at semicon~ c~tor plane. It is easier to see an I Fn looking at it straight on 10 than looking at it from an angle. There~ore, prior art lanterns using LEDs o~en place the LEDs in a circle, so that the LED light will project outward in a 360-degree range.
One example of such a lantern is ~ osPd in U.S. Patent No. 5,224,773 (Arimura) ~ os-ps a flq~hing lantern desigred to co.l~pe ~te for the low 1ll ~
and poor side visibility of LEDs. Arimura uses a mllltihlde of LEDs a~ ged about a 15 cylindrical support member. The LEDs project radially from the periphery of the support. This arrqngemPnt compPn~q~tp~s for the low side visibility of LEDs. Theentire support is housed within a ma~.;l'jing Leanel type lens that further disllibuLes the light emitted by the LEDs. In order to increase the l~..l.;nqnce of the lantern, alternative Pmbo~limpntc are shown that contain mllltiple layers of LED rings. The 20 result is a compleY lantern configuration cQn~ ;ng a mllltih)de of LEDs. In ~d~ition~
the light produced in any one direction is only produced by a few LEDs and, therefore, is not very bright.
Recent improve...~lls in LED technology have resulted in the creation of LEDs having signifi~ntly increased ln.l~ Ance The increased LED lllminqnce decreases the need for a large number of LEDs to produce the high amount of light required of a fl~shing lantern. ~ltho--~ even modern LEDs do not produce enough light for a sir.gle LED to be used in a flqching lantern, it is now possible to produce fl~hing lanterns with fewer LEDs than in the past. The present invention is directed to providing such a flqching lantern.
Summqry ofthe Invention The present invention is a flq~hin~ lantern that inrludes an array of LEDs posiflon~ in a plane so as to emit light in a direction ~,c.~rn~ic~lqr to the plane. A
reflector is positiorled above the plane of the LED array. The reflector is position~d so as to l~lil~;l the light produced by the LED array in a particular desired direction.
The array of ~ FDs and the reflector are surrounded by a h~lspare.ll or opaque ma~i~g-type lens that con~ es the light produced by the planar array of T Fns ~ 16~07~

4-in a 360-degree arc. A power source and control circuit are provided to ~ 'e the LEDs.
In accor~ce with further aspects of this invention, the reflector is in the formof an inverted cone centrally aligned with the planar LFn array.
In acco.dance with other aspects of this invention, the LED array is circular and the lllagr~ying lens has a cylindrical con~ ration.
In a~ d~ue with still further aspects of this invention, the magnifying lens is a L~ el type lens.
In acco~ance with yet other aspects of this invention, the fl~hing lantern in~ln~çs a relatively rigid base. The array of LEDs is mollnsed atop the base. In addition, the base supports the magn;ryi,~g lens. ~efelably, the control circuit for controlling the fls~ g of the LED array is housed in the base. The power source may be housed in the base or may be eytern~l to the lantern.
In accordance with still other aspects of this invention, the LED fl~chir~g control circuit in~ dçs an electronic switch, preferably in the form of a metal oxide silicon field-effect transistor (MOSFET), a timer, and an onJoff switch. The MOSFET is co--l-P~led in series be~ the power source and the array of T T;ns.
When the MOSFET is con~u~ing current is supplied to the array of LEDs causing light to be produc~d From the foregoh-g description, it will be appreciated that the present invention provides a new and improved fl~hing lantern. The invention provides a sirnple lantern configuration spe~ific~lly desi~P~ for use with LEDs. The present invention's simplifie~ configuration does not re~uire the n~llltit~de of LEDs incorporated in previous lanterns, res~lting in a lantern that is easier to assemble and install. The present invention Pffi~iPntly solves the problem of poor side visibility by incorporating an inverted conical reflector that reflects LED light emissions in a full 360-degree arc. The present invention also enjoys a longer life than in~n~esc~ntlanterns and has improved vibration-re~i~t~nce characteristics.
De3~ ion of the Drawings The foregoil g aspeets and many of the ~tten(1~nt adv~nt~gPs of this invention will become more readily appr~;a~ed as the same be~ es better understood by ~,rere~ce to the following de~t~il~ de~li~ion, when taken in conj~n~tion with the acc~,~.p~ ing &~willgs, WllCre~
FIGURE 1 is a side elevational view of the pre~rllly prefelled embo~impnt Of the present invention;

s FIGURE 2 is a plan view of an array of LEDs inrl~lded in the embodiment of the invention illustrated in FIGURE 1 taken along line 2--2; and FIGURE 3 is a srhemq~iC diagram of a control circuit that causes the LEDs to ~ash periodically.
Detailed Desc~ ion ofthe Flerellcd Embodiment FIGIJRE 1 is a side elevational view of the pl~llly p,ere"ed embo-lim~nt of the invention. More sperific-q-lly, FIGURE 1 illustrates a flqching lantern 11 that co,llpl;aes a cylindrical base 13, an array of light-~mittin~ diodes (LEDs) 15, a ll~Spatl.-l. Iens 17, and a conical refiector l9. As is best seen in FIGU~E 2, the rray of LEDs 15 is arranged ullir~ lly in a subst~nti~lly hol~olllal plane atop the base 13. There are thirty-six LEDs in the array of LEDs 15 of the present embodiment of the invention. Six sets of LEDs are co~-~-ec~ed in parallel. Within each set, there are six LEDs conn~ led in series.
The l~anat)~.ll lens 17 is cylindrical in shape and in~ludes a fresnel-type lensconfi~tration around its cylindrical periphery. The Lla~l,dre.ll lens 17 in the prer~lled embodiment is ll~1spale.ll. In a second embodiment, the ll~nsp~en~
lens 17 is opaque. The ll~nsp;~ nl lens 17 in the prcrt;lled embodiment is also a magnif~ring-type lens. The ~ spare. 1 lens 17 is mol~ntecl atop the base 13 such that the lower end of the lens surrounds the array of LEDs 15. ~ollnted within the ll~sl,arent lens 17, preferably integral to the upper end of the transparent lens 17, is the conical reflector 19. The conical reflector 19 is inverted and positioned such that the tip of the reflector is centered above the array of LEDs 15. The conical reflector 19 is preferably made of plastic coated with a reflective layer.
Housed in the base 13 is the control circuit 23 that controls the application ofpower to the array of LEDs 15. The power source 31 may be mounted in the base 13or may be external to the base 13. In any event, the control circuit 23 and the power source 31 are sc~ ally illustrated in FIGURE 3 and described below.
FIGI~RE 2 is a plan view taken along line 2 2 of an array of LEDs 15 sllitable for use in the embodiment of the invention shown in ~IGURE 1. The illustrated array of LEDs 15 comprises two orthogonal lines of LEDs that intersect at their centers, plus a plurality of LEDs located in each quadrant created by the intersecting Lines.
Obviously, other arrays can be chosen, if desired. There are currently thirty-six LEDs in the present embodiment of the invention. The precise nun~bcr and orientation of the array of LEDs 15 will, to some extent, depend on the desired direction of light 35 emicsion The precise pl~c~ of the LEDs on the subst~nti~lly ho,~onLal plane ~.. ,~ 2168075 can also vary. Further, various shapes, sizes, colors, and ;..le~-C;l;eS of LEDs can be used.
In operation, when the array of LEDs 15 is e. clg;~d, the light emitted by the LEDs h~ gf5 on the outer surface of the conical reflector 19. The conical

5 reflector 19 is posifionP~d so as to reflect im~ng light outwardly, through the ll~is~,are.lL lens 17. An exemplary ~micsjon path is shown as item 21. The conical nature ofthe refiector 19 causes reflecte~ light to be dir~iled o~ ~dly along a 360-degree arcuate path. Obviously, refiectors of other shapes could be chosen, de~en~ g upon the desired light emicrion path.
FIGllRE3 is a ~,r.hPm~tic diagram of a control circuit23 and a power source 31 suitable for use in the embodiment of the invention shown in FIGURE 1.The array of LEDs 15 inr~ several sets of LEDs c~nnP~cte~ back to back in series, with the sets co~ eled in parallel, thereby c,ea~ing a matrix of LEDs. FIGURE 3 also inr~ les a DC power source 31, a timer 33, an onloff switch 35, and a metal15 oxide field-effect transistor (MOSFET) 37. The source terrninal (S) of the MOSFET 37 is connp~cte~ to the anode end of the array of LEDs 15. The c~thode end of the array of T FnS 15 is connPcted to the negative terminal of the DC power source 31. The positive terminal of the DC power source 31 is co~-n~cle~ to the d~n terminal (D) of the MOSFET 37. Thus, the MOSFET forms a power switch 20 connPcte~ in series with the power source 31 and the array of LEDs 15. The output of the timer 33 is connected to the gate (G) terminal of the MOSFET 37. Power issupplied to the timer 33 from the positive terminal of the DC power source 31 via the on/offswitch 35.
In operation, the timer 33 is started by closing the s~vitch 35. The timer 33 25 supplies a series of pulses to the gate terminal (G) of the MOSFET 37. Each time the timer33 applies a pulse to the gate(G) of the MOSFET37, the MOSFET37 becomes con.1uc~ive, whereby current flows between the drain (D) and source (S) terminals of the MOSFET 37, el~r~ g the array of LEDs 15. Because LEDs have only a very low voltage drop across them when forward biased, the large currents30 passing through forward-biased LEDs cause high-intensity light to be emiKed by the LEDs. Thus, the pulses produced by the timer 33 cause the array of LEDs 15 to flash brightly on and off. The prefell~d timer rate lies b.,.-.~n 20 and 80 pulses persecond.
The fl~ching lantern 11 is ~ hP~ to a stationary or moving object via the 35 base 13. When the on/off switch 35 is in the "on" position (i.e., closed) as noted above, the array of LEDs 15 are f~lward biased by the current _ow through the MOS~ET 37, causing the diodes to esnit light. When the on/off switch 35 is in the "off" positi~n (i.e., open), the current through the MOSFET 37 is ~ y zero, wLer~ the array of LFDs 15 no longer provides ill~..,.;.,~l;orl The timer 33 controls the s~il.,l~irg on and offofthe MOS~ET37. When the array of TF.ns 15 produce S illll.,.;n l;on the majority of the emitted light radiates away from the individual I Fns toward the inverted conical reflector 19. The T Fn light is reflecte~ by the i conical reflector 19 ou~war~lly through the lens 17 along a 360-degree arc.
While the presel-lly prefell ~d PmhodimPnt of the invention has been illu~llaL~tand d~lil.ed, it will be applcciated that various çh~g~s can be made therein wilLoul 10 dep~ling from the spirit and scope of the invention.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A flashing lantern comprising:
(a) an array of light-emitting diodes mounted in a plane for emitting light in a direction perpendicular to the plane;
(b) a reflector positioned to intersect the light emitted by said array of light-emitting diodes and redirect the light outwardly through a predetermined arc;
(c) a magnifying lens surrounding said reflector, and (d) a control circuit for controlling the application of power to said array of light-emitting diodes such that said array of light-emitting diodes flashes on and off.

2. A flashing lantern as claimed in Claim 1, wherein said predetermined arc is a 360-degree arc.

3. A flashing lantern as claimed in Claim 2, wherein said reflector is a conical reflector positioned such that the apex of said conical reflector points toward said plane in which said array of light-emitting diodes is mounted.

4. A flashing lantern as claimed in Claim 3, wherein said array of light-emitting diodes includes a plurality of sets of light-emitting diodes, said sets being connected in series, said sets including a plurality of light-emitting diodes connected in parallel.

5. A flashing lantern as claimed in Claim 4, wherein said control circuit comprises: a metal oxide silicon field-effect transistor (MOSFET) connected in series with said array of light-emitting diodes; a power source connected to said MOSFET
and said array of light-emitting diodes to supply power to said array of light-emitting diodes when said MOSFET is conducting; and a timer for supplying pulses to the gate of said MOSFET that cause said MOSFET to become conducting

6. A flashing lantern as claimed in Claim 1, wherein said array of light-emitting diodes includes a plurality of sets of light-emitting diodes, said sets being connected in series, said sets including a plurality of light-emitting diodes connected in parallel.

7. A flashing lantern as claimed in Claim 6, wherein said control circuit comprises: a metal oxide silicon field-effect transistor (MOSFET) connected in series with said array of light-emitting diodes; a power source connected to said MOSFET
and said array of light-emitting diodes to supply power to said array of light-emitting diodes when said MOSFET is conducting; and a timer for supplying pulses to the gate of said MOSFET that cause said MOSFET to become conducting.