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Publication numberCA2171244 A1
Publication typeApplication
Application numberCA 2171244
Publication date9 Sep 1996
Filing date7 Mar 1996
Priority date8 Mar 1995
Also published asDE19608898A1
Publication numberCA 2171244, CA 2171244 A1, CA 2171244A1, CA-A1-2171244, CA2171244 A1, CA2171244A1
InventorsYukio Yamuro
ApplicantYukio Yamuro, Hiyoshi Electric Co., Ltd.
Export CitationBiBTeX, EndNote, RefMan
External Links: CIPO, Espacenet
Variable color led device and led color control device
CA 2171244 A1
Abstract
A variable color LED device emits variations of luminescent colors, and an LED color control device (current control circuit) controls the emission (color and intensity) from the variable color LED device.
Luminescent diodes R, G, and B are provided in a single variable color LED device 10 to emit light of red, green, and blue. The electric current flowing to the luminescent diodes is controlled for each color by a current control circuit 15. The current control circuit 15 comprises, fox example, variable resistances 16r, 16g, and 16b. Optionally controlling the electric current through the variable resistances allows the quantity of light of each of optical three primary colors, thereby emitting a mixed color from the luminescent diodes of the variable color LED
device 10. Thus, variations of luminescent colors can be successfully emitted. The device can be used both indoors and outdoors as a display picture element for a color display device, etc. Its small picture element realizes a precise image.
Claims(6)
1. A variable color LED device, comprising:
luminescent diodes for each of optical three primary colors.
2. The variable color LED device according the Claim 1, further comprising:
a plurality of luminescent diodes for each of the optical three primary colors.
3. A LED color control device comprising a variable resistance circuit having a plurality of variable resistances mounted on a foundation base with luminescent diodes for each of optical three primary colors, wherein said variable resistances are connected to one or more terminals of said luminescent diodes for each of the optical three primary colors to variable control an electric current flowing in one or more luminescent diodes.
4. A LED color control device having a variable resistance circuit having a plurality of variable resistances luminescent assembled in a body with luminescent diodes for each of optical three primary colors, wherein said variable resistances are connected to one or more terminals of the luminescent diodes for each of the optical three primary colors to variably control an electric current flowing in one or more luminescent diodes.
5. A variable color LED device comprising;
one or more luminescent diodes corresponding to each of optical three primary colors, wherein a terminal unit of said luminescent diodes is made of hard metal in a plug shape as being mounted outside.
6. A LED color control device comprising:
a socket for connection to a plug-shaped hard metal terminal unit being mounted outside of a variable color LED device, wherein said socket including a variable resistance circuit for connection to said plug; and said variable resistance controls an electric current flowing in one or more luminescent diodes each of optical three primary colors of a variable color LED device.
Description  (OCR text may contain errors)

'96-03-07 16:35 FR0~ 2Jl`` ~ ~*.~ . 2 i / 1 L 4 4 P.5~42 ~arlable Color LED Device and LED Color Control D-vic~

Ba~hy~ d of the Invention Field of the Invention The present inven~ion relate~ to a variable color LE~ d~vice which emits various coloxs and ~n LED ~olor control de-vlce for controllin~ the emissi~n (vari~tions and in~ensi~y of color~) from the va~iable color ~ED device.
Descri~ion ~f the ~lated Art There have been lu~inescent element~ used conventionally wi~h various colored ligh~s (for ~xample, red, green). Particularly, ~ light emitting ~iode (LED) has be~n ~ell-known as a small a~d power-sa~ing device, ~na is use~ for various d~splay devlce~.
FI~ lA ~hows a top ViQW of a conventional LED
device. FIG. 1~ shows the cur~ent control cir~uit o the L~D d~vice. A~ L~D device 1 shown in FIG. lA
comprises d substr~te 2 provided with a luminescent diode 3. The lurineccent d~ode 3 is covered with a lens-shaped prote~tive transmission oover. A curren~
~ontrol circult is connected to the LE~ deviee 1 as 25 ~hown in FIG. lB. The ~urrent ~ontrol circui~

l6-03-07 16:35 FROM:~ *.:~4:~. 2 i / P.6~4Z

oomp~ ~e6 tel In~l units 4 an~ 5 an~ a vari~bl~
re~i~tanCQ 6. The termlnal unlts ~ and 5 are - co~na~t~d to a power source with the termin~l unit 4 directly connected to the cathode of the luminescent diode 3, and with the terminal unit 5 connected to the ~node of the 1~ e~cent dlode 3 through the variable resistance 6. The above described term~nal units 4 and 5 ~re connected to th~ extern~l power sourc~ ~not ~hown in ths attached dr~wings). When ~ bias voltage i~ applie~ in the forward directlon with the above descri~ed ocnfiguration, the lum;nescellt diode 3 e~it~
light. The color of the e~itted li~ht depends on the mat~rial of the configuration of the luminescent diode 3. For example, when the con~i~ur~tion refers to Ga-As in the p-n junotion, an i~xaxed light is emitted.
When the configu~ation ~e~ers to G~-P with an 02-dop~d ~miconduc~or, a red light is emitted. When the configuration refers to Ga-P with an Na-doped samiconductor, a g~een co~or is emitted. Furthermore, a luminesGent diode emittin~ a blue light h~s ~cently b~er~ developed for pract~cal use. The qu~ntity of llght emltte~ by a luminescent diode dep~nds on the electric current flowin~ through a bia~ Úlectric voltage. Therefore, ~he quantity ~f lig~t ~an b~
changed by con~rollin~ the re~is~ance value of the ~-03-07 16:35 FRo~ 2~ Y*~ 4~ Ll 7 1 ~ q ~ F.7,'~2 var$able xesi~tance 6.
Such ~n LED device ~s dcsi~ned to emit li~ht of a single color irom a ~in~le unit. For example, even i a plur~lity of l-lr;n~R~ent diodes ~re mounted in a Šinyle LED device, the lumine~cent diodes are to emit light of q single (same) color.
Assumin~ that such LED device~ are incorporated into ~ display device as picture elements, t~e pictu~e elements of a commvn di~lay device should be for lC~ v~ious colors. Therefore, acc:ording to the related a:rts, LED devic;es separ~tely emitting one o~ primdries ~re provided in three devi~e units t~ obtain a desired colo~ by mixing the luminescent c:olor~ from the three LEI;) devices. One LED device i~ ~bc~ut 3 - 5mm in diameter. The~efore, a combination of 3 LED devices fo~ optlcal th~ee primary colors makes a display picture elemen~ as ~ig as a circle circumscribing ths three LED devices. As a result, one ~isplay picture elem~nt iR l~ - 15mm in diameter.
It is 4 times as bl3 as a single L~ device, and is rath~r '~r~e as a display pic~ur~ element. Even if the three L~D devices are mounted closely to ea_h other, the clear~nce ~etween ~he luminescent diodes cann~t ~e small enough to appropriately mix optical three primary colors. ~he~eforOE, ~vsn i~ the mixed ~6-~3-07 16:36 FRo~ 2~ *~ P.8~42 2 ~ 4 ~

color may b~ ~c~eptable when viewed ~ro~ a distan~:e, it has the prob~em when viewed closely t~t op~ical thre~ primary colo~s c~nnot be sufficiently mixed, but are re~gnized separately. Under ~uch conditions, forming a displdy device using con~entional ~
devi~es, each of which cor~e~ponds ~o a di~lay picture e1e~ t, ~akes up ~ ver~ l~rge d1splay device, the~eby un~avorably li~itiny the use ~f the davioe to th~ case ~here the dev~ce is viewed from a dist~nce.
Furthermore, the LE~ devices for ~hs abov~
de~crib~d combin~tion should be pro~ded ~s many ~s the number of re~uested colors for each use.
Therefore, when the ~ deviees are prepared. three types o~ the LED devices should be assigned for optical three prim~ry coloxs. The LED devi~es should ~lso be as~igned to each type o~ light quantity cont~ol corre~ponding to the light mixin~ ratio~
Thus, there have been th~ pro~lems that the LE~
devices give the user~ trouble in appropriately maint~in~'ng the LED devices ~ b~ing classified cor~espondin~ to ea~h type of ~llmi~e.~cent color when they are manufactured and put on sales. The~e is another problem that the ~on~entional devlces require a considerably l~r~e store house to keep them i.n type ~S uni~A. Furthermore, ~n maintaining the dis~lay devi~e ~ 03-07 16:36 FROM:~2J~ $~ J. P.9~42 2 1 7 1 ~4i'1 conta nin~ the LED de~c~s, the lumi~e~cent colors and light ~uantity are lncorrectly managed in the prooe~s of main~aining the display devicQ cont~lning the LED
devices when a new ~ED de~ce i~ 1e~ibly used dep~n~tng on the l~inescent light. Additionall~, troublesome operations are required to prevent the problems f~om occux~ing.

S~mrnary of the Inven~lon The present inventlon aims at solving the above list~d problems associated with the prior ~rt technologies~ According to the pre~ent inventio~, An LED devi~ is provided ~y ~ounting a l.~ esc~nt diode ~it~ln~ each o~ optical th~ee ~rimary colors on a substr~te. This re~ers to ~ v~ria~le color LED
device. Tho varia41e color LED device comprises a current control circuit ~or controlling correspon~n~
to each color an electric c~rrent to be ~acŠed to each 1~ in~CcQnt diode provided on the s~Štrate.
Confl~ured ~ d~cri~ed above iŠ the LE~ color control devi~e~
Thus, the varidble ~olor LE~ devica c~n emit ~ny colors by config~ring the LED color control device ~ith th~ luminesccnt diodo emittiny e~ch color of 2s op~ical throe primary colors on a single substrate, - 36-03-07 16: 36 FROM~ ~ Y$~ J~ P. 10~42 -2i 71~4~

~nd by controlling for e~ch color the ~lectric current to the l~-in~cent diode, Thus, the LED ~evice can ba us~d ~ ~ small-8ize lumlne~nt displ~y picture element for v~ri~u~ color dlsplay devices, si~nal devices, et~.
That lS, the following effects can be ob~ained a~cording to the variabl~ color LE~ dhvic~ and LE~
color control device of the present inve~tion. First, since all co~ors can ba emitted by on~ va~iable color LE~ device, a small-size luminescent ~i~pla~ picture ~lement can be realizod for use outdoors and indoors in various co~or displ~y devlce, si~nal device, eto., there~y obt~inl ng an improved display picture image as Compare~ with the combinatlon of 3 L~D devlces each emlttin~ ~ single color. Second, whe~ the v~ri~ble cDlor LE~ ~evice ls used as a lumlnescent signal devic~ ~mittin~ vari~tions of oolors, the r~umber of ~l~nal lamps can be 1 re~ardles~ of the number of colors to be freely switched, thereby allowing much freedom ln designln~ the 6i~nal lamp ~or it~ lo~ion and arr~n~ement. Third, since ~ single varlable color LED devlce can be used to emit all colors, lt does not require sep~r~tely storing fo~ eac~ color in manu~actuxin~ and ~ale~ proce~ses. ~ven if it is incorpor~ted into ~ di~pl~y device, eto., the LED

l6-03-07 16:~6 FRa~ 2J~ *~ P. 11/42 ~i71244 dcvlce at har~d does not ha~o to be used only ~or a ~pec;~ fled color, thereby removt n~ trouble in storin~
th~ devic~, savin~ sto~age space for the stook, simplifyinš~ th~ assembly l?roces~, and allowin~ easy 5 m~intenance.

~rief Description of the Drawings FIG. lA ls a top view o ~he ~onven~ivnal LED
device;
FI~. lB show~ the cu~re~t con~rol ~ir~it of the LE~ dev~ce;
FI~. 2A iS a top view of the variable color LE~
device a~ording to the first e~boaimen~ of the ~rQsant inVention;

FIG. 2~ is a ~ide view of the variable colo~ LED
devioe acco~ding to ~he firs~ embodim~nt of th~
present in~Qntion:
FIG. 2C lc ~ bottom vi~w ~f th~ ~ariable color LED
device ~cc~rding t~ the ~irst embodiment ~f the 20 pr~sent in~entior~, FIG. 3 shows the variable color LE~ device and the current control circuit for controlling cu~rent of the ~evice accor~lng ~o the ~rst embodiment of ~he pre~nt in~ention;

~5 F~G. 4A ls a top view of the varlable color LED

36-03-07 16:37 FROM:~2~1"1`7*.~ ? ~ P.lZ~az device according to the second e~bodiment;
FIG. 4a s~ows the cirouit of the vaxiable cclo~
LED ~evice and c~rrent control circuit;
FIG. 5A shows the variable color LED device and current control circuit for controllin~ the c~rr~nt of the devlce according to the thtrd embodiment;
FIG. 5~ shows the vari~ble color LE~ device and GUrrent control circult for controlling the current of the device acco~ding to the fourth em~odi~lent;
FIG. 6 shows the variable color LED device and current control ci~cuit ~or controlling tha c~rrent of the device accordin~ ~o the ~i~th embodiment;
FIG, 7~ shows the variable color LE~ devic~ and current control clr~u$t fo~ cont~ollin~ the curren~
of the devi~ according to th~ si~th embodiment;
FIG. 7B shows the varia~l~ color LED device and curre~t ~ontrol circ~it for controll.in~ the current of the devtce accordin~ to the sev~nth ~mbodiment, FIG. 8 shows the variable color ~E~ de~ice configur~d to omit light in various colors limited ~y the seventh embodiment of the present invention: and FIG. 9 s~ows an e~ampl~ o~ the Ópplication of th~
var$able color LED ~evice acco~aing to the preQ~nt invention to ~ si~nal lamp.

~6-0~-07 16:37 FROrl~ 4~ P.1~42 DescriptiOn c t~e Freferred r bo~ s The embodiment accordin~ to the pre~ent in~ention is desc~ibed below by referrin~ to the ~tt~hed drawlngs. FlG. ~A 18 the top view o~ the variable color LE~ device acco~ding to the first e~bodi~,ent of the present inventlon; FIG. 2~ is the Šlde view of the devicÚi ~nd FIG. 2C is the bottcm view of the device.
As shown in FIGs. 2A throll~h 2ó, ~ v~riqble c:ol~r 10 L~ device lO comprises ~ circular sub~trate 12 on a body 11. On the substrate 1~, three i~ in~Scent diodes R, ~, and ~ are mou~ted. A protective covex 13 covers the su~s~rate 12 ~nd ~ll these three luminescent di~des ~, G, and ~. Four tormlnal units 14~, 14g, 14b, and 14 are led from the bottom of the body 11.
The above described red luminescent dlode R em1~s red liyht. ~h~ gr~en luminescQnt diod~ G emits g~e~
light. The blu~ luminesoent diode ~ e~it~ ~lue l~ght.
The5e luminescent diodes R, G, and ~ ara arra~ged at equal intervals along the ~ircumference of the substrat~ 12. In ~IG. 2A, th~ luminescent diodes R, ~, and 3 a~e ax~ange~ s~ch tnat the cathode sides f~ce the center of the substrate 12 while the ~node si~es face ou~slde the substrate 12. ~he cathodes o~ the 96-03-07 16:~7 FRGI`1:~21~ $.j~4~. P.14~42 2~7124~

luminescent diodes R, G, and B are directly ~onne~ted to a common ~ermin~l unit 14 while the anodes ar~
separately connected to terminals 14r, 14g, and 14b through the current control circuit descrihed later.
~he protective cover 13 i~ made of ~ transmissible ~ateri~l. The tran_mission can b~ obt~ined throu~h a tran~parent or semltransparent material. However, it is desired that the ~at~r~al lS sem~transparent and photodlffu~ible so that the mixin~ of optical three primar~ color3 o~n be properly made.
FI~. 3 shows the connaction betw~n th~ vaxiable color LED device 10 and the current control circuit ~LED color control device). As ~hown in FIG. 3, tha c~thode of each of the luminescent diod~s R, G, zn~
~ is connect~d to the term~nal unit 14 while thQ anode of e~ch of the~ i3 connecte~ ~o the terminal units 14r, l~g, and 14~ through th~ vari~ble resiStan~es l~r, 16g, and 1~ ~f the c~rr~r.t control circuit 15.
The terminal unlts 14r, 14g, and 14b ~re ~onneoted to the plu~ terminal of the power source (not shown in th~ attachsd dxa~Jin3s~. ~he common terminql unit 14 i~ connected to the minus termin~l of the power souxce. The current that flows to th~ red luminescent dlode R aan ~e controlled by ad~usting the re~ist~nce v~lue of the v~riable ~esistan~e 16r. T~e size of th~

96-03-07 16: 37 FROM: ~2~ *.J~4~. P. 15~42 ;~ 2 ~ 4 current aontrols the amount of emisslon. Likewise, the a~ount of ~mission ~rom the lumine~cent diode G
can be controlled by adjustlng the resistance o~ the v~riable resist~nce l~g, ~nd the emount of emlsslon from the luminescent diode ~ ca~ be controlled by adjus~in~ the resistance of the v~iable resi~t~nce 16~.
The va~i~ble resista~ces 16r, 16g, ~nd l~b of the current control ci~c~it 15 axe not show~ in the atta~d drawi~gs. They can be pxovided in the body 11 shown in FIG. 2B, and their vaxiable re6i~tance units are interlocked with a sm~ orew th~t o~n ~e tuxned optional d~g~es ~lockwise or ~oun~QrclockwiŠe using ~ driver, etc. externally. Thus, the ~oltage ~cu~rent) of ~he three luminescent diodes R, ~, and ~ for op~ical three primary colors can be f~eely controlled. That i~, th~ quantity of' ligh~ o-f the 11 iney~nt dio~es R, G, or ~ can be optionally cont~olled whi~e tho ~E~ deYice is powered~ ~hus, the desired ll~r1nP-qcent color can be optionally ~et while usin~ the driver ~nd w~tching the en~ire lumiAescent color.
Since the variable color LED device 10 of t~e present invention ls prov~ded wlth the ll-m~n~ent diodes R, G, and a emitting optic~l three primAry 96-03-07 16:38 FRO1~ 2~" I`'Y$~ 2 i 7 l ~ ~ ~ P 16~42 colors, the varl~le color ~ED dev~ce c~n emit any tone of ~olor by ~x~ n~ the there colors.
For ~xa~ple, ~hen red is req~i~ed entir~ly, th~
resistan~e value o~ variab~e ~esistan~e 16r is de~eased to power o~ly t~e red l~minescent diode R, ~he reslstance values o~ ot~er variable re6i~tances 16~ and 16b ~re in~eased to the ~xi~u~ values to power off the lumlnescent dlodes B and G. When green is r~quired entirely, only th~ green luminescen~ diode G is powered whlle the lumine~cent diode~ R and ~ are powe~ed off. Like~se, when blue is requir~d entirely, only th~ blue lumine~oQnt diode ~ i~ powered while othe~ luminescent diodes R and ~ are p~wered of~. When ~he vari~ble col~r LED device tries to emit 15 any o~ the other aolors, the resistance value of each o~ ~he variabl~ re~i~tanoes 16r, 16g, and 16b is adjusted to appropri~tely control the amount of the electric c~rrent flowin~ to the l~min~ent diod~ R, G, or ~ sa that opti~ three prim~y ~o7ors are appropriately mixed to obtai~ a deslred color.
Each of the variable resistances are not provlded in the body 11, but ~an be mounted in ~n external perlpheral dev~oe. For example, the te~minal ur.i~s 14r, 14g, 1~, ~nd 14 ~re formed not as a flexib}e m~tal l~ad1 n~ llne but as a hard metal plug te~ lnŠl 96-~3-07 16:38 FRO11:~ $~:J"4:J. 2 1 7 ~ ~4~ P.17/42 unit to real ize the simllar result b~ setting a varlable ~esi~tance ~etw~en th~ lnput terminal unit and output te~ l unit of the 40cket coupled to the plug terminal units. In this case, the resistance value ean be easily set if the va~iable re~istance ~s llnearly mounted ~long the ~xi~ of the sock~ with th6 ~o~ket shAped longer ~t it9 re~ por~ion. The resi~t~nc~ value can also be set easily ~y leading ~rom the side of the socke~ th~ leadlng li~e con~eo~in~ th~ socket to the pow~x s4urce, and by providing the ~etting unit of the ~ariable resistance with the top o~ a screw arran~ed at the rear portion ~f the soc~et. That ls, the socket can be optionally shaped as long ~s the v~ri~ble resi~t~nce can be properly set.
I~ a current control circuit is provided inside or outside the a~ove described sock~t or the vari~ble colo~ LED de~ioe, and lf the ~urrent control circuit is controlled by the displ~y oontrol cir~uit acco~din~
to a~ image signal, then the ~ariable colo~ ~ED device can also be used as a display pictuxe element of a dyn~mi~ ima~e~ The control b~ the di~play ~ontrol circuit can be made by pre~arin~ a look-up t~blo indišating the relatio~ship between the intensity ~i~nal of the imags signal and ~ach va~ieble '96-03-07 16:38 FROM:~r2~ *.~ . P.18/42 21 11~

~e6i~ta~e of the curra~t con~rol ~irc~it ~rough which the di~pl~y picture element (varlable color LED
device) emit~ ht (colors~. Using tne lookup table, an im~ge sign~ n ~e converted in~o a variable resistanca control si~nal.
Thus, a luminescent pictu~e elemen~ th~t e~its various colors on a single ~ devi~e can be configured ac~ording to the present invention. The size o~ the emi~ting sur~ace of the ~E~ device is ~me millimeters long and is ver~ small. Therefore, very precise i~age c~n b~ o~tain~d wh~n th~ device is ~sed as a display pi~ture element of an outdoor display devica. It i~ obviou~ that a pr~Gise ima~e c~n be obtained when the device is used as a display lS picture element of an indoor displa~ device.
In the ~bove describe~ embodimen~, a total of 3 luminescent diodes, each o~ which is used to emit one of opti~al three prim~ry colors, are provided i~ a single ~ED device. ~wo lu~in~schnt diod~s ccn ~lso be pro~ided for each of opt~cal three primary colors.
Thls a~lication is described b~low ~s the s~cond e.. b~ nt of the present inventio~.
FI~. 4A and 4~ ~ho~ the se~ond embodiment in which two lumlnescent diodes are provided for ea~h of optical t~ree primary colors. FIG. 4A is a top ~iew 96-03-07 16:38 FRO~ 2J~ *~ P. l9i`~Z

~ 1 7 1 ~ Ll 41 of the varia~le c~lor LED de~ice. FIG. 4B sho~ ~h~
vaxi~ble color LE~ devica and th~ curren~ cont~ol circ~it for con~olling the aurrent~ As shown in FIG.
4A, a ~ariAble ~olor LED devic~ 20 i~ pr~vided with a tot~l o six luminescent diodes, that is, two red luminescent diodes Rl and R2, two green lu~ine~cent diodes Gl and G2, ~nd ~wc bl~e lumine~cent diode~
and B2 o~ a sub~trate 22.
Th~ variable color LE~ device 20 shown in FIG. 4A
ls similar, a~art from the n~m~r of terminal units, in sh~pe ~o the body 11 of the variable c~lor LE~
d~vi~e 10 shown in FIGs. 2B and 2C as viewed from the side and bottom (although the si~llarity i5 not shown in the ~tta~hed drawings). Th~ variab}e color L~
device 20 is sm~ller than 5mm in ~ia~eta~ of the emitting suI ~2c~, 4nd i~ very small and covered with a p~otective tr~nsmisslon cover at i~s top.
In thia case, the luminescent diodes Rl, R2, Gl, G~, B1, a~d B~ are arran~ed at equal intervals along the circumferen~e of the su~st~ate ~2. As s~own i~
FIG. 4B, the anodes of the lumlnescent diodes Rl, R2, Gl, G2, ~1, and B2 are connected ~o the terminal u~it 14 whlle the cathodes of them are connected to t~e te~min~l unit~ 14r-1, 14r-2, 14g-1, 14g-2, 14b-1, and l~b-2 throu~h the variable resistances 16r-1, 16r-2, 96-E~3-0~ 16:38 FR011:~2~ $;1~ p.Z0/4~

16~-l, 16g-2, 16b-1, and 16b-2 of a current control cixcuit 25. That ls, a total of 7 te.rminal units ax~
l~d from th~ bottom o the b~dy.
In the case according to the second embodiment, th~ tarm~nal un7ts 14r-l, 14r-2, 14g-l, l4g-2, 14b-l, and 14b-2 are connected to the pl~5 term~nal Gf the po~er source while the ~om~on terminal unit 14 is connected to the ~inus te~m~ nal of tne power source.
The amount of emie~ion from t~e r~d lu~in~cent diod~
Rl an~ R~ is a~usted b~ controlling the current -~ith th~ resistanc~ ~alu~s o~ th~ Ya~iabl~ re~i~tances 16r-l and 16r-2 properly adjusted. Likewise, the amount of ~ission from the green lu~inescent diodes Gl ~nd G2 is adJusted by controll~ng the resistan~e valu~s of the v~riable resistances 16~-1 and 16g-2. The amou~t of emlssion frPm the blue luminescent diodes Bl an~ ~2 ~s adjusted by controllin~ the resist~nce ~alues o the variable reslstances 16b-1 and 16b-2.
Alao in the second embodiment, ~s in the first ~0 embodi~ent, each o~ t~e variable resistances 16r-1 thxough 16b-1 of the c~r~ent contxol clxcuit 25 can be provided in the body unit, and sm~ll screws lntexlockln~ with the vaxlable units of the vaxlable resist~ce~ ~re turned using a driver, etc. to adjust the xesis~nce v~lues. Othexwise, the termlnal units '96-0:3-07 16:39 FRO1~ 2~ *~ Gj~ P.Z1~42 ~1 7 l ~44 14~, 14g, 14b, ~nd 14 are formed BS a hard metal plug term$nal unlt to realize the simllar result by setting va~iable xesistdnces 16r-1 throu~h 16b-2 batwe~n th~
input termin~l unit and output termir.~l unit of ~he S socket coupled to the plug terminal u~its. In thi~
ca~e, each of the varlable resistances 16r-1 through 16b-2 c~n be controlled using a lookup t~ble throu~h an external display cont~o~ clrcuit so that the devi~e can be used as ~ display picture element ~f a dyn~mic image.
Since the second em~odiment is tw~ time~ as many as the abo~e desc~ibed irst embodiment in n~mbe~ of lumines~en~ diodes, the amount of e~isslon from the luminescent diode is two tim~s ~s ~uch from the entire ~ariable color LED device 20. Therefore, even if the devi~e is used outdoors as a display picture el~ment of the di~play device, ~uffi~ient amount ~f emission (intenslty) can be obtained, thereb~ form~ng a precise i~nage .
According to the abDve de~ribed embo~ nt, the variable resistan~e and terminal on the ~no~e si~e are arranged such that t~ey co~respcnds one by one ta each lumine~cent ~lode. However, the axrangement and connection of the variable xesi~tanc~ and terminal on ~5 the anode side to the l~inescent diode are not 96-03-07 16::39 FROM:~2h" ~ ~*.~ . P.2Z/42 ~1712~4 limitcd to this embodiment. ~escribed ~elow as other embodi~ent6 are the arran~ment and connectton of the v~riable resist~n~e and terminal on the ~node side to the lllmine~ent diode.
FIG. SA shows the variable color LED device and the current control circuit for controlling the current according to the third embodiment. As in th~
second ~mbodiment, a va~iable color LE~ devlce 30 is provided with ~ luminescent diodes, ~nd their cathodes are connected to t~e common ~erminal 14. Ac~ordin~
to the emb~diment, on the ~node sides, l~mine~aent diodes Rl and R2 are conne~ted in parallel, ~ ine..scent diodes Gl ~nd G2 a~e connec~ed in parallel, and luminescent diodes Bl ~nd 132 are connected in parallel to the output terminals o the vari~ble re~i~tance~ 36r, 36~, and 36b respectively for each c~lor. The input terminal~ of the varia~le resistan~es 36r, 36g, and 36~ ~re connected to the terminals 34r, 34g, and 34~. This is the only di~ere~ce ~f th~ third embodi~ent fr~m th~ ~e~ond e~ho~ i m~nt . That is, ac~ording to the third embo~;~ent, two l~inesc~nt diodec ~re p~ovided for each color of opt~cal three p~imary colors. ~he curxent fo~ th~ luminescent diodes can be cont~olled ~S not individu~lly a~ in the secand embo~i ~n~, but 96-03-07 16:39 FROI~ 2t~ *,~ P.2~/42 ~171 ~4 collecti~el~ controlled fcr a p~ir of l~mlne5cent diodes fo~ the same col~r. In tht~ ca~e, when the variable color L~D device 30 is combined with ~
current control ctr~uit 3S, a total of ~ tGrminal unlt~ axe led.
FIG. 5B shows the variable color LED d~vic~ ~nd the ~urrent control ~ir~uit for controlling the ~urrent acco~dln~ to the fourth embodime~t. In this am~odiment, a vari~ color L~ device 40 is provided, as ln the s~oond dnd third embodiments, tha luminescen~ diodes Rl, ~2, Gl, G2, ~1, and ~2 with a pair o~ the diodes mount~d for each of optical three p~imary colors. ~owever, ašcording to the fourth ~mbodiment, the luminescent diodes are ~ol~neGte~ in series for each color, end ~ p~ir of lumine~ce~t diodes connected in s~ries for ~ch ~olor (red luminescent dio~es RL an~ R2, green luminescent diodes G1 and ó2; and ~lu~ min~ont diod~s ~1 and B2) ~re respectively connected to the output tel inals of the v~riable rQsistances 46r, 46g, and 46b respectively.
The input ter~inals of the va~iable resistances 46r, 46~, and 46~ are cor~ecte~ to the te~in~l units ~
44g, and 44b respectively. This is the dif~erence b~tween the third ~nd fourth embodiments, In the fouxth embodiment, a total of ~our terminal units a~e '96-03-07 16:39 FROM:~2J~ *.~ - P.24~'4Z

~712~4 led with the coni~ura~10n o~ the variable color LED
device 40 ccmbinad with ~he ~urrent control ~irauit 45.
The vari~ble color L~D device ~nd current control 5 circuit can be conflgured a6 ~ot being ~ombined with e~ch other in the third ~nd fourth embodiments. ~hat is, the current control clrcuit can be connected a~
an external device to the variable eolor LED device through a so~ket, etc. Also the variable resistanc~
can be controlled on the ~ispl~y in real time ~ccor~ing to the l~age sl~nal uslng the ~is~l~y control device ~nd lookup ta~le.
FIG. 6 shows the variable colo~ L~D device according to the fi$th embodiment ~nd tne current lS control circuit for controlling the current. FIG. 7A
show~ th~ vari~ble color LED device accordin~ to the SiXth embodiment and the curre~t control oircuit for controlling the current. FI~. 7~ ~hows the variable oolor LED devioe acc4rdin~ to th~ seventh ~-~o~ent and t~e current ~ontrol circuit for cantrollin~ the current.
A ~ariable color LED devi~e 50 ~hown in FIG. 6 accordtn~ to the fifth emb~di~ent is provided with tot~l of nine luminescent diode~, that is, three red .25 l~ ;nR.qc~nt dioda~ Rl, R2, and R3; three green 96-03-071640 FROM~2~ *.j~4~ 4 4 P.Z5~2 luminescent diodes ~ 2, and G3; ~n~ thre~ blue luminescent diodes ~ 2, an~ ~3 on the su~strate.
The variable color LE~ dovice 50 shown in FIG. 6 is also similar in shapQ, apart from the number of tenminal unlts, to the body 11 of the variable ~olor LED device iO shown in F~Gs. 2~ and 2C ~s bein~ viewed frorn the side and bottom. However, the similari~y i~3 not shown in the ~tached d~win~s. The variable color LED devica 50 can dl~o b~ ~ormed about 7 or ~
mm in diameter of ~he lumineccent surrace, and ~he de~ice ls covered with a transmissible protective cover.
The lu~inescent diodes R1, R2, ..., ~2, ~nd L3 are arranged along the circumference o the substrate ~t lS e~uAl intervals. The anodes are conne~te~ to ~he common terminal unit 14 while ~he oathod~s ~re conneoted to th~ t~rminal ~ni~s 14r-l, 14r-2, 14g-1, 14~-2, 14b-1, and 14b-2 thrcugh the va~iabl~
resl~ta~ces 5~r-l, 56r-2, 56r-~, 56g-l, 56g-2, 56g-3, 56b-1, 56b-2, and 56b-3 of a current control cir~uit 55. That is, if the v~ria~le color L~D d~vice 50 is ~.bineA with the cur~ent cont~ol circ~it 55, ~ total of 10 terminal ¨nits ~r~ le~ fro~ the bottom o~ the body.
In this ~xample, te~min~l unlts 54r-1 through 54b-96-03~7 16:40 FROM:~2~ *.:J~4~ 44 P.~6/12 3 ~re con~ect~d to the plu~ terminal of t~e power so~rce ( not shown in th~ attached drawin~s ), an-l ~he -_ terminal unit 14 i~ connected to the minus terminal o~ the powex source. The amc~unt o~ emission 5 from the red lumine~cent dlodes Rl through R3 is controlled based on the resistance values of the variable resistances 56~ hrough 5~r-3. ~he a~oun~
of emission from the green l~ ne~cent diod~s ~1 ~hrough ~3 i6 controlled ~sed on the resistance valu~s of the ~ariable resistances ~g-l thro~h 5~g-3 T~e amount of emission irom the ~lue luminescent diodes B1 throu~h B3 is controll~d basad on the resistanc~ values of the variable resistances 56b-~through 56g-3.
A vari~ble aolor ~ED devi~e 60 ~ccording to ~he sixth e~bodiment shown in F~. '7~ is, as ln the fifth e~bodim~n~, is provided wit~ ~ total Of 9 lum1nescent diodes. The cathodes are connected to the ~ommon terminal unit 14 while the anodes of th~ three ~0 lumine~cent diodes ~or each color ~re connected to the outS;~ut tl3nninals of variable resist~nces 66r, 66g, and 66b in series. rrhe ln~u~ te~ i n~ of the va~iable resist~nces 66r, 66g, and 66~ are conn~cted to t~rminals 64r, 64g, and 64b. Thi~ is the difference 2S ~etween the fifth ~nd sixth embodlments. Th~

~-03-~7 16:40 FRO~ Y*,~~ 44 P Z7/42 according to the sixth embodimcnt, three l~mines~ent diode~ ar~ pr~vided or e~óh o~ opt~cal three prlmary colors. The current ~hat flows to the luminescent diodes is not individually controlled as in the fifth S ~ ~o~i ent, ~ut a set of three luminescent diodes is aollectively controlled for the same lu~inescent color~ If the varlable color LED device 60 is ~n~ined with a cu~re~t control cir~uit 65, a total o~ ~ t~xminal unlt6 are led f~om the device.
A v~riable color L~ device 70 according to the ~eventh embodiment ~hown in FIG. 7~ is the s~me as the devic~ according to the fifth and sixth embodiments in that the three ra~ lumine~cent diGd~s Rl, R~, and ~, thr~e green luminesšent dio~es Gl, ~2, and G3, ~nd 15 ~hree blue luminescent diodes B1, ~2, a~d ~3 a~e provi~ed for respective ~ol~rs of optical thre~
prim~ry colors. Howe~er, according to the sevšnth ~mbodiment, t~ree luminescent ~iodes are co~ne~ted in series for each color, and a set of three lumineacent diodes con~ected in series (red l-~m1ne6cent diode-q ~l, R2, ~nd R3, ~reen lumine3c~nt diodes Gl, G2, ~nd G3;
and blue l~minP~ent diodes Bl, B~, and B3) ar~
aonnecte~ to the output ~erm~ ,C of variable resi~t~ncP~ 76r, 76~, and '7~ re~pectively. The i~put t~ ;~Als of the vari~b~e res~stAnC~ 7~r, 76g, and ~6-0~3-07 16:4E~ FRO1~ 2J~ *.:~4:~. P.28~42 2 1 1 1 ~4~

76b ar~ connec~ed t4 te~minal units 74rr 74y, ~nd 74b.
This i~ the differ~noe between the fifth and six~h embodiments. In th~ 5 embodiment, if the variable color LED device 70 is combined with a current ~ontrol circuit 75, a total of 4 termlnal units ~re led rom the devi~e.
In the fifth, sixth, an~ seventh embodiments, the variable color LE~ dovi~ is not combined with the current control Gircuit, ~u~ the current control circuit can be co~ne~t~d as an e~tern~l devioe t~ the variable color LED device through a socket, et~. The variable ~sistance c~n be controlled on the display in real time acco~ding to the lma~e signal using the display control device And loo~up ~a~le.
FIG. 8 sho~s ~n e~ample of the vari~bl~ color LE~
de~lce configu~ed ~o emit various lumi~es~ent colors limited by the seventh embodim~nt. Tho v~riable color LED device shown in FI~. 8 is provided with eight chip ~esl~tances 87 having res~ective r~sis~an~e values, two red lumi~sc~nt diodes R, fo~r green luminesc~nt diodes G, and two blue lu~inescent diodes ~ on a sub-~trate 82. Thus, the luminP~cent diodes do not helve to be equal in ~ ~bsr for ~3~ch color. In other w~rds, sin~e the ~uantit~ o~ ht of e~ch of the ~5 optical three prlmar~ ~olor~ ifi prede~ermined ~o emit 96-03-0'7 16:41 FRO1~ 2Jl~ $.~ . 2 1 7 1 ;~ P.29~4Z

a requested colo~, the number o the 1~1 ;n~cent dlodes can ba deteL ;~e~ accordin~ t~ the pre~etermined quantit~ of llght ~or ea~h of the optical three pr~mary colors. Furthermo~e, appropriately ~witchin~ the ~onnect~ons to the chip resistances enabl~fi a desired ~olor to be emitted from ~mong limited v~riations of colors. If ~ tri~ming reslstance (v~riably set ~s a ~esis~nce value by tri~ing ~ resis~ance chlp uslng, for example, a laser light) is used as a chip resist~ce for controlling the current of the ~arLable color LE~ d~vice, th~
re istance ~alue c~n be optionslly v~ried.
As described above, any num~er of l~minescent diodes c~n be used for ea~h of optical three prlm3ry colors in the variable color LED device o~ the pre~ent in~ention. It is obviou~ that the larser ~he number of the l- ~nescent diodes is, the larg~r guantity of light is emitte~. The eonfi~uratio~ of the ~urrent con~rol circuit and the connection to the c~rrent control circuit c~n be cont~olled depending on the confi~uratlon in ~aeh a~bodi~ent. Addition~lly, sin~e a lig~t of ~ny color can be emitted on a sln~le varlable color ~ED devi~e, the funct~ ons ~f plu~lity of ~onventional em$~tin~ devices can be performed by ~ single emitting device (~risble color 96-03~7 16:41 FR01~ $.j~. P.3E~/4Z

LED d~ice).
FI~. 9 sho~s an applic~tion of the variqble ~o]ar LED device fox uRe in th~ traffic signal lamp~. It shows a new variable color LE~ device according to ~he present ~ention ~elow a traffic ~ignAl ld~p shown just $or comparison. The traffic signal lamp shown in FIG. g comprise~ a red signal lamp 84; ~ yellow signal lamp 85. and a ~reen signal lamp 85. It functions ~9 traffic ~i~nal lamps by ~eq~entially e~ltting ~he thr~e colors. That i5, three emitting devices are usea to exclusively e~i~ a specif iod color. On tho other h~nd, using the varicble ~lor LED device according to the present i~vention, the system comprises only one signal lamp 87. qlhe eu~re~t control circuit controls ~or each color the electric current to ~he luminescen~ diode. When the varioble color LED devlce lndlcate~ red, ! t emits r~d light.
~Ih~n th~ variable ~olor LED dev~ce indic~te~ yellow, it emit~ yellow li s~ht . When thQ variable color I,EI~
20 dev~ ce indicates ~reen, it emits gre~rl light .

Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US73855749 Apr 199810 Jun 2008Cree, Inc.True color flat panel display module
US78300951 Jun 20069 Nov 2010Koninklijke Philips Electronics N.V.LED assembly and module
US796909730 May 200728 Jun 2011Cree, Inc.Lighting device with color control, and method of lighting
US799302117 Nov 20069 Aug 2011Cree, Inc.Multiple color lighting element cluster tiles for solid state lighting panels
US868576613 Mar 20121 Apr 2014Toyoda Gosei Co., Ltd.Solid element device and method for manufacturing the same
US87668854 Jun 20081 Jul 2014Cree, Inc.True color flat panel display module
US886641024 Oct 200821 Oct 2014Cree, Inc.Solid state lighting devices and methods of manufacturing the same
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Classifications
International ClassificationH01L25/075, G09G3/14, G09G3/32, H01L25/16, H01L33/48, H01L33/02
Cooperative ClassificationH01L25/0753, G09G3/32, H01L25/167, G09G2300/0452, H01L2924/0002
European ClassificationH01L25/16L, G09G3/32, H01L25/075N
Legal Events
DateCodeEventDescription
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