CA2231649A1 - Product life timer - Google Patents

Abstract

An electrochemical cell is used as a timing mechanism. The cell is sized to supply electrical power to a display for a period of time related to the intended life of a product. The display remains in an active state in response to a level of power output by the cell above a threshold and reverts to a default state in response to a level of power output below the threshold. The cell and the display can be arranged in layers on a common substrate for incorporation into a label or product packaging.

Description

PRODUCT LIFE TIMER

Technical Field The invention relates to the field of electrochemical timing devices, particularly those used for measuring product life.

5 E3ack~round Many manufacturers ea~er to ensure the best performance of their products advise consumers of their products' expected shelf or service lives. For example, the packaging of products that degrade predictably with the passage of time are often imprinted with a date 10 indicatin~ the time of their manufacture or the time within which the products should be sold or used. "Sell by:", "use by:", and "expiration date:" notices are now commonplace on perishable goods.
Sornetimes, tl~e expiration date of a product depends upon when Ihe product is put into service. Some such products degrade 15 preclictably with use, and otl~ers begin to similarly degrade upon exposure to the environment. Examples include air fresheners, pet treatment collars, air and water filters, and cosmetics. Since tlle expiralioll date of sucll pl-oducts is not knowll at the time of theil-mallu~act-lle, mallufact-lrers generally advise only on their intendecl 2 0 length of service and rely on their customel-s to calculate tlle actual expiration date from the date the product is entered into service and the suggestecl length of service.
In place of written notices, timers are l<nown that automatically advise customers of product life. Mecllanical and 25 electronic timing mechanisms are generally too expensive for tllis purpose. Accordingly, much of the attention of this art llas been directed to the development of less expensive chemical or electrochemical timers. Tl~ese latter timers generally rely on slow cllemical reactions or the migration of materials to produce a 3() cumulative change in appearance with the passage of time. None of these timers have enjoyed much commercial success.

Bradley et al. in U.S. Patent ~,292,916 disclose a disl~osal~le ~ el ancl product sloracJe condition inclicator with two alternative lyl~es of tillliny n~ecllallislllc,. An insoluble inl< of one of tlle li~l~ing nlecllallisllls Illiyrales ll)rouyll a barrier layer at a conlrolled rate to 5 l~roduce a color cllange visible tl~roucJh a stencilecl palleln. A solul~le ink of llle olller lillliny mecllanislll dissolves in lhe pl esence of a Illiyl aling nlixlure lo r eveal a similar stencilecl patlel n. Bolll timers are actlvalecl by releasing llleir miyl atiny 111iXIUl es fl olll illlpel vious confillelllellls Also, bolll lillling nlecllallisllls are sensilive lo 10 al~ ienl concliliolls, especially temperatul e. AccorclillcJly, tlle lilners ale irllellded fol use on ploducts wllose selvice lives ale silllilarly affeclecl by lhe sallle concliliolls.
I<ally et al. in U.S. Palelll ~ 0~1,275 use an aclvanciny color cllancJe i~oundary in an electrochl omic strip lo Illarl< llle passacJe of 15 lill-~e. All eleclrocle dissolves irl an acidic electrolyte, injectilly eleclrolls into llle eleclroclll olllic stril~ ancl causincJ a reaclioll lhal cllemicaily alters lhe elecllocllromic sllil~ along tlle color cllange boulldal y. Lil<e tlle above-clescl ibed cllelllical limilly Illecllanisllls of Bradley et al., tlle electrocllelllical timiny mecllanislll of Kall~ et al.
20 is also lemperal~ e sensilive. Aclivalion is also similar by leleasiny llle aciclic electrolyle froln confinelllent. I-lowever, tlle aciclic eleclrolyle is dancJel-ous allcl limits tlle usefullless of lllis linlel .
A Inucll earliel- U.S. Patent 3,0~5,179 lo Maier discloses a solicl 25 stale elapsecl time indicator in whicll an eleclroclllolllic display is powerecl by an external electrical source. Tl~e electrochrolllic disl)lay, wllicll is relcltively insellsitive to lellll)eralul e val iations, yl-aclually cllancJes in color witll tlle flow of cun-ellt. A r esislol-conllectecl in series willl Ille display regulales llle flow of CUI rellt 30 tllrouJIl tlle clisplay. A series switcll activales lhe tilmel. Tlle gradual chelnical challye in the display provicles tlle timiny mecllallislll. Tlle electrical source is requil-ecl to maintaill tlle flow of currenl at a steacly rate until tlle color challJe is complete.
Kuo et al. in U.S. Palent 5,250,905 disclose a batlery tester 35 tllat is conllecled in pal-allel witll a battery to conlllloll exterllal loacls. rlle lestel- is ilself all electlocllelllical cell llavillcJ ollly a tilly flactiol-l of tlle L~attely's cal~acily. Tlle electrocllell~ical cell's voltacJe is also less tl-lall llle volla(~ e of tlle l~allely, so llle cell c~oes llol l~ecJill to cliscllalcJe Lllltil llle t~clttery's volta~e clrol~s; allcl wllell it 5 cloes ciiscllalcJel a Illucll llicJllel inll~ec~allce of tl-~e electlocllelllical cell slows its clisclla~e lale to Illatcll tlle c~iscllarcJe rate of tlle l~allely.
DUIillCJ ils cliscllal~e, all allocie of tlle electlocllelllical cell cJlaclually oxiclizes, I-evea~ a Inessaye.

AccolclillJly~ tlle tilnillcJ f~lllctioll of l<uo eL al.'s L~attel-y testel-10 is also l)er~ol l~lecl liy a ~l acl~lal clletllical cllall~e i~ e clisl~lay. Like all of tlle otllel electlocl~ell~i(,al timillcJ l~ecllallisllls clescril~ecl at~ove, el~eryy is sul~l~liecl to suppol-l all irlevelsilJle cllenlical leaclioll tl~at l~erlllallelllly cl~all~es tl~e clisl~lay's appealal~ce. Tlle amollllt of chall~e is a f~lnctioll of llle cu~ llalive anlount of curl ellL Illat l~asses I '; Illlou~l~ Llle clisl~lay.

S ~ l y o f I ll v~ i o ll OUI il~velltion illclucles a till~illCJ l-llecllcll~islll tllat ol~erates il-lclel~ellclel~tly of visil~le cl~elllical oi- PI1JISjCaI cllal~es ill a clisl~lay of a l~l-oc~ucl life till~el-. Illsleacl o~ s~ orlill~ c~ ilive cllallcJes i~
e clisl~la~, all elecll ocllelllicLIl ceil l~l-efel-al~ slli~ls ll~e clisl)lay ~et~;!eel~l active allcl (lefa~llL slales ill accolclallce '.'!ill~ ils l~ower ~ull~ . Al)ove a Illl-esl~lolcl l~o~vel OUIl~Lltl tlle clispl~y rell~aills ill all aclive state; all~ elov~ le sallle tlll-esllol(~, tlle clisl~lay revel ts lo iLs c~efault stale. ~i~lle cliscllal~e rale of tlle cell i;, ecl~latecl wit 25 l~locluct lile so tllat Ille clispla~/ lelllaills ill its acLive stale llllol~cJlloLlt tl~e il-llellclecl life of tlle l~l-ocl~lcl all(l Ic-~ielts lo ils clefaull slale at tlle exl~ectecl el~cl o~ l~loc~uc,t li~e.

ll-l col~tlast ~iLI~ Ll~e usllal recl~lilell~ellls fol electl-ocl~ell~ica cells, wllicll illvolve Inaxinlizill~ powel cal)acities, tlle 3~) élecll-ocllen~ical cells of oul irlvenlion have only lin~ilecl l~ower capacities. Tl~is enal~les a wicler selectioll of ll~aterials for nlal<illcJ
tl~e cells, incluclin~ safer, ellvirollll~entally Golnpatil~le malerials, as well as less exl~ellsive Inaterials that contl il~ute lo ease of -ll c~ f a c t ~l l e .

I~he eleclrocllelnical cell ralllel- tllan tlle display ullclel goes a cllenlical cllan~e to pl ovicle a liming mecllanislll. Tlle display mel-ely reflecls cliffel-ellt levels of l~ower outl~ul l~y Ille electrocllelllical cell. ~or exanll~le cliffel-ellt states of the clisplay can be tricJ~el ecl l~y 5 cliiferellt levels oF tlle electrocllenlical cell s power output. One of tlle states is plefelal~ly an aclive slate ll-icJgel-ecl by l~ower output above a given tllresllold. Tlle otllel state is pl-efelal~ly a default state trigyerecl by l~ower oulput below the cJiven tllresllold.
l~ile active slate can disl~lay a message affillllillg the plOC~UCt s 10 efficacy and tl~e clefaull state can display a Illessa~e indicalillg tl~e nee~ ~or refull~isllillg or replacilly llle product (or even no Inessage at all). Tlle electrochelllical cell is desiyned to outl~ut a level of power above the tllresllold tllrougllout the expecled life of the product tllereby Inailllaillillg tlle display in the aclive stale tllrougllout the 15 sallle l~eriocl. A dlop in tlle electrochemical cell s power output al llle end of lllis pel iocl allows the display to revel l lo its clefault slale inclicalillcJ Ille encl of pl oduct life.
A cilcuil conlrollecl IJY a switch prefel-ably intelcollllects tlle electlocllelnical cell ancl tlle clisl~lay. Resistance of the cilcLIil '0 inclucles inlel-llal resislallce of tlle eleclrocl-lemical cell ancl tlle clisplay as well as any aclclilional r esistors usecl lo l eJulale Ille rale of discl-larcJe frolll tlle electrocllelllical cell. l~lle switcl-l wllicl~ opetls - ancl closes the CilCUit can be used to start llle tinlill~ Illecllanislll.
OUI new pl ocluct life tilnel can l~e usecl as a stallcl-alolle tinler 5 incorpolcltecl witllin plocluct pacl<aJinJ or macle as a lal~el tllat can be relnoval~ly moulltecl on procluct packagilly. Tlle lal~el version can l~e l elllovecl frolll tlle l~roduct packa(Jillg wllen tlle product is first put into service ancl remounted in a new location where it can l~e more convelliently observed. A switcll for activatiny the timel can be 30 closed aulomatically UpOIl removcll or remoulltillg of tlle label or can l~e closecl nlallually al lhe converlience of the customel-.

Drawin~s FIG. 1 is a circuil diagral11 sl1owing an arlal1cJel11ellt of product life timer willl discreet components.
FIGS. 2A and 2B illustrate two diffel ent states of a display 5 con1t)ol1el1t of tl1e pl-ocJuct life timer of FIG. 1.
FIGS. 3A, 3B, and 3C illustrate three clifferent states of the display compollellt.
FIG. ~l is a cross-sectional view of al1 inte~l atecl version o~ OUI
l~l oclucl Iife timel- incol porated ~vithil1 a label.
-l O FIGS. 5A and 5B illustlate anotl1er integraled version of our procluct life timer incol porated witllin product packa~il1y. A cross-seclional side view is l~rovicled in FIG. 5A, and a cross-secliol1al to view is l~rovidecl L)y FIG. 5B.

Detailecl Descriptiol1 l 5 In a ~asic forl1~, OUI l~rod-lct life tin~el- 10 incl~lcles foul well-I<nown electrical coml~onel1ts: an electrocl1el11ical cell 12, a ~lisplay -I ~I, a resislor -l 6, and a switch -l ~ all joinecl lo~etller within a COIlllllOIl circuit 20. Each of the compol1el1ts can be n1ade in a variety of ways frol11 a variely of n1alelials; l~ut eacll is l~refelably arral1ged 20 in a layerecl forl11 for assen1bly inlo a lal)el, a ploducl l~acl<age, or olller lal-nil1aled slruclule. Examples of sucl1 layered slructures are clescribed in more detail later.
U.',. Palent 5,350,6~5 to Lake et al., whicl1 is l1ereby incori~ol ated by refel ence, discloses a lan1il1ated array structure 25 that includes a numbel- of individllal IJattery cells that can be used as tl~e electrocl1emical cell 12 of our pl-oduct life til11el- 10. Tl1e cells of Lal<e et al. include tlle usual anode, electrolyte, and cathode layers spaced by suitable masl<ir1g. Substrates sul~porling the anocle and catllode layers for m conductive end caps for connecting the cells to 30 external circuits.

Anoll~er exan1l~le of an electrocl1emical cell tl1at can L~e used as llle elecllocl1ell1ical cell 12 Of OUI plodLIcl life limel- 10 is clisclosed in U.S. I~alenl 5,055,9~3 lo Nisl~i el al., wl1icl1 is also incol l~orate~l t~y refel-el1ce. Nishi el al.'s cells are formed l~y an il1-line plocessil1y 5 lecllniclue as a ~all of al~ infolmaliol1 cald. Eleclrocol1~uclive ancl l~allery aclivalor n1alel-ials are applied in pallel ns to adjacel~l surfaces of two webs, ancl an electlolyte impregnalecl sheet is n1ounled 011 one of llle web surfaces prior to laminaliny tl1e two we~s togell1er.
Tl~e display 1 4 pl efel ably l~as at leasl two distincl states for displayincJ one or mole contlastil1y messayes 22 as showl1 in FIGS
2A and 2B. One of the stales, illustlated by FIG. 2A, is an active slale triggel-eul by applicatiol1 of a voltaye (i.e., electrol11o~ive force) above a given tl1resl1old. 1~1-~e otller of tlle states, illustrated by FIG.
15 2B, is a clefa-llt slate (no InessaJe) trigyelecl by a cJrop in ll1e vollage l~elow lI)e tl1l eshol~J l~lle n1essaJes can ~e conveyecl in wol cls, colors, Syllll~OIS, 01' olller Jrapllics.
I~IGS. 3A-3C illustrate an alternative combinatiol1 of tllree distincl states fol the cJisl~lay 14. The first state, showl1 in FIG. 3A, 20 is an inilial state, l~riol- to powel being applied for a first time. Tl1e second al1cl tl1ilcl states, sl1own in FIGS. 3B and 3C, ale active ancl clefaull slales triygered similal- to tlle correspol1dil1g stales of FIGS.
2A and 2B. All tl1ree slales l eveal word n1essacJes 2G, 28, ancl 30.
-ri~e clisl~lay l ~I can inclucle an eleclrocl1rol11ic matel ial tl1a 2 5 I)rocluces a r eversible cl1ange in color in r espol1se to ll1e applicatio of voltaye between OppOSil1CJ electrodes. For example, the messaye 22 of ll-le active slate of FIG. 2A can be procducecl l~y a color cl1ange in ll1e elecll ochromic matel ial from a color matcl~ing a l~acl<grouncJ 2'1 of Ibe dis~lay to a color that conll-asts willl the bacl<yround 2'1. The 30 default slate of FIG. 2B restores the color of the electrocl~romic matel ial to ils initial color matcl1il1g the background 24.
Tl1e inilial state of FIG. 3A can be proclLIced by a removable filnl overlay 32 that covers tlle message 30 conveyecl by the cdefault state. Tl1e active and default messages 28 and 30 of FIGS. 3B ancl 3C
~15 can l~e l~rocluced l~y Wl itincJ thel11 against a baclcgroul1d 34 in colors Illat conll ast witll t~ackground colors assumed by the eleclrochromic mcllel-ial. Tlle active InessacJe 2~3 is written in a color tllat nlatclles tlle initial color oF tlle electroclll-olllic material l:)ut contl asts witl tlle color of llle electroclll-olllic material after voltaye is applied.
5 l~l-le default Illessaye 30 nlatclles tlle color of tlle electroclllolllic matel-ial aftel- voltaye is appliecl but contrasts witll the initial color of tlle eleclrochlolllic material.

U.S. Palent 5 ~113 739 to Coleman wllicll is llereby incorpol-atecl by refel-ellce discloses an electroclll-olllic display tllat can be used -10 as tlle clisplay 14 of our pl-ocluct life timer 10. Coleman s display is also a lamillate made up of various composite layers between eleclrocles. Color cllanye occurs in response lo a voltaye applied across tlle electlocles at an interface between an ionically conductive layer and a layer of electrocllromic nlaterial.
Tlle circuit 20 conl~ects the display 1 ~ in series witll tlle electl-ocllelllical cell 12 anc~ tlle resistor 1 G. A total lesistance of tl-~e circuit 20 whicll limits a cdischal-ge rate of tlle electrocl~elnical cell 12 is a SUIll of tlle resistallce contributed by tlle electrocl-lelllical cell 12 tlle display 14 and the resistor 16.
20 Allerllalively llle resistel l G can l~e conllectecl in l~arallel willl ll-le disl)lay -1 ~ lo inclease tlle discllarye rate. More cells can L)e conllectecl in series to increase the available electromotive folce. A
furtller moclified circuit can be used to conlpensate for resistance flucluatiolls of tlle clisplay 1~1 and to l-naintaill tlle tlll-esllold voltaye 25 acloss the clisplay 1~1 tllrouyllout tl~e expected life of tlle electrocl-lemical cell 12.
Any pOI tiOIl of the Cil CUit 20 can be intel-l-uptecl by tl-~e switcl I 8 includilly intel nal layers oF the electrocllemical cell 12 or tlle display 14. Closing the switch 18 starts the timing mecllanism of ;30 OUI product life timer 10 by completiny the circuit 20 ancl shiftiny tlle display 16 from its default state to its active state. Tlle eleclrocl~elllical cell 12 is sized to supply electrical powel to the clisplay 16 at (at least) tlle thl-esllold voltaye for a period of tinle correspolldiny to an intended life of a product. The switcll 18 can be 35 constructecl in a variety of l<nowll ways such as IJY arranyilly a pair of concluctive layers tllat can be actively moved illtO COIltaCt Ol biased inlo contact UpO11 removal oF an inLel-l11ediate insulatil1~ layer.
A n~LIcll widel- clloice of materials is available for placticin~ o~r invel1tiol1 becaLIse the funcliol1al requil-en1el1ts for each compol1ent 5 are less stringent thal1 the requil-el11ents associatecl witll theil- reyular use. I~or example, maxil11iziny the power capacity of the electrochel11ical cell 12 is generally not necessary, because its capacity for a ~iven clischarye rate is equated with a limited procluct li~e. Reaction time of the display 1~ to shift between clifferent states lo is also less critical. Accordil1gly, otl1er objectives can be oplil11ized by malel-ial selections includil1g cost, safety, ancl ease of anufacLul-e.
Procluct life tin1el- 40 depicled in FIG. 4 is incorpol-ated withil1 a label 42 l1aviny tlle usual layers of a substl-ate ~-~, a pl-essure sensitive aclllesive 46, an~ a release linel- 48. An electrocl1emical cell 52, an electrocl1el11ical clisplay 54, a resistol- 5G, ancl a swilch 5 are assen1bled in layers 011 the substl-ate 44. Tl1e elecLrocl1el11ical cell 52 llas an electl-olyte layer G0 between two electrocles 62 and G4 (anocle and cathode). l~l1e electrocl1el11ical disl~lay 54 has electrolyte ~o ancl electrocl1l-ol11ic layers GG ancl 68 between two electrodes 70 and 72.
Examples of electrolytes for tlle layers 60 and ~G inclucle polyethylel1e oxide, electrolytic adhesive sucl1 as hydrogels, or an1n1ol1iul11 chloricle in a gel. The electrodes 62, G4, ancl 72 can be, 2~5 amol1g other thil1gs, copper, silver, alumil1ul11~ mal1yal1ese dioxide, Zil1C, carbol1, lithiLII11, or sulful-. Tlle electrode 70 can be made o~
sin1ilar materials including alul11inum, zinc, carbol1, lithiul11, ancl sulfur or of indiul11 tin oxide. Electrocl1rol11ic materials, sucl1 tllose listed in the Colemal1 patent, includil1g polyaniline, poly-pyrrole, 30 polytl1iopl1el1e, nicl<el oxide, polyvinylferrocene, polyvioloyen, tungsten oxide, iridiLInl oxide, molybdenun1 oxide, and Prussial1 blue can be used in layer 68.
Pairs of cond-lctol-s 76, 78 and 80, 82, whicl1 can be made fro a carbon-based inlc of higl1 conductivity, straddle the electrodes 62, :35 G4 and 70, 72 of the cell 52 and tl1e display 54. Tl~e conductors 78 ancJ ~2 are conneclecl l~y tlle l esislol 5G, wllich call l~e IllacJe of a lliylr esislance carbol~ asecl illl<. The switch 5~ intel rupts a conllectioll l~etween the conductors 76 ancl 80. A non-cond-lctillg acillesive masl<
~4 olherwise separates the electrochemicai cell 52 from the 5 electrocllemical clisplay 5~, allcl another sul)strate 8G covers both the cell 52 and tlle display 54. The sul~strate 86 is l~referal~ly a trallsparellt polyester ~illn, l~ul pal~er Ol card stock witll an opellillcJ
~or viewing tl~e display 5~ coulci also be used. A grapllics layer call l~e appliecl to tlle substrate 8G ~or colnlllullicatillg inforll-lation 10 allcl ill-lpl oviny al~peal ance Olle tellllinal 90 of tlle swilcll 5~3 al all el-lcl o~ e conclllctol- 7G
is laicl on tlle noll-collductive adllesive maslc ~1, ancl anotller ternlirlal 92 al all ellcl of tlle conduclol û0 is laid in a collal~sil~le clil~ le 9~1 of Ille substl-ate ~G. DeplessincJ tlle climple 9~1 moves the termillal 92 15 irllo conlact witll tlle lerlllillal 90 fol coml~elillg a CilCUit belween llle electlocl~elllical cell 52 allcl tlle eleclrocllelllical disl~lay 5~1, lriggel iny a cllancJe (roln all illilial stale lo all aclive slale ol llle clisplay 5~1. Prefelal~ly, llle clisl~lay 54 relllaills in ll-~is aclive stale ulllil powel capacily of llle cell 52 is nearly exllauste~. A relnovaL~le 20 overlay similar to tllat showll in FIG. 3A call be used to cover the clisl~lay ulltil it is aclivatecl, sucll as by relllovill~ tlle overlay.
Anotiler examl~le of an illteyrated product life tilnel- 100 is ~epicte~ l~y FIGS. 5A and 5B. The procluct life timer 100 is incoll~olatecl into a l~roclllct l~acl<aye 98. Similal- to llle prececlillcJ
~'5 elnboclilnellt, an electrocllelllical cell 102, an electrocllelllical display 10~, a r esistor 106, and a switcll 108 are moullted Oll a sul~stlate 1 10. Materials similal- to tllose listed in the plececlincJ
eln~oclilllelll can l~e usecl to fol ln tllese corllpollellts.
A l-lon-collcl-lctillg aclllesive Inasl< 11 2 sepal-ales tlle cell 1 02 3() alld tlle clisplay 10~ and boncls to a pl-illtable layer 1 1~1, wllicll is ll ansl~al ellt at least in llle ViCillity of tlle display -10~1. A 9l a~llics layer 1 1 G Oll llle pl intal~le layel 1 1~1 allcl tlle sul~stl-ale -1-10 also forln illlegral pOI tiOllS of the pl ocluct packaye 9~3.
In contlast to tlle precedillg embodilllellt~ electrocles 1-lG ancl 3 r; 1 1~ (allocle and catllocle) al e laicl out laterally Oll tlle suL)strate 1 10.

CA 0223l649 l998-03-lO

j 10 An electrolyte layer 120, wl1ich is initially isolated by a breal<able seal 12 1, covers both electrodes 1 16 and 1 18. The breakable seal 121 functiol1s as tlle switch 108. The display 104 includes overlyiny electrolyte and electrocl1l-on1ic layers 122 and 124. A pair of 5 concluctol-s 12G and 128, whicl1 al-e also laid out laterally on tlle subsll-ate 1 10, conl1ect the electrodes 116 and 1 18 to the clisplay 10~. The resistel 106 connected in parallel with the display 10 regulales a rate of dischal-ge from the cell 102. The conductors 12 ancJ 128 are sl~apecd in complemel1tary pattel-l1s ul1clel- tlle 0 electrocl1l~omic layer 12~l lo clisplay a message.
Wl1en tlle cell 102 is activaLed by bl-eal(il1J the seal 121, a pOltiOI1 of tlle electrocl1l-ol11ic layer 124 acljacent to one of tlle concluctol-s 12G lightel1s in color and anotl1er pOltiOI1 of tlle electrocl1lol11ic layer 124 adjacent to the other conductor 128 darl<ens 5 ill color. Col1trast between the diffel-ent color portiol1s of the electl-ocl~lol11ic layer 124 can be used to reveal a message similar to l-IG. 2A.
Alll1ougl1 only two examples l1ave been depicted, those of skill in the art v~/ill appl-eciate tllat the layers of cells and clisplays in our .~o integl-atecl pl-oduct life timel-s can be arranged in a variety of ways, includil1J beil1J stacked one llpon anotl1er. The default state of the display can be the same or clifferel1t from an initial state. For examl~le, the default state can undel-go a chel11ical cl1ange associatecl with tlle drop in voltage withil1 tlle cell. The display could ~, also be dividecl into different portiol1s for clisplayin~ different n1essaJes in tlle difFerent states. In addition to proclucts per se, our lil11er can also be usecl to tin1e events.

Claims (35)

1 1 We claim:
1. A product life timer having a timing mechanism that operates independently of visible changes in a display comprising:
an electrochemical cell that discharges at a controlled rate to provide the timing mechanism;
said display having active and default states and at least one of said states displays information concerning the product life;
said electrochemical cell being electrically related to said display to shift the display between said active and default states in accordance with different levels of power output by said electrochemical cell; and said display remaining in said active state in response to a level of the power output of the electrochemical cell above a threshold and said display reverting to said default state in response to a level of power output of the electrochemical cell below the threshold.

2. The timer of claim 1 in which said electrochemical cell is made in a succession of layers including two electrode layers and an electrolyte layer, and said display is also made in a succession of layers including an electrochromic layer and an electrolyte layer.

3. The timer of claim 2 in which both said electrochemical cell and said display are mounted on a common substrate and interconnected by a pair of conductors.

4. The timer of claim 3 further comprising a switch interrupting one of said pair of conductors for opening and closing a circuit between said electrochemical cell and said display.

5. The timer of claim 3 further comprising a layer of adhesive on said substrate for mounting the timer on another object.

6. The timer of claim 1 in which said electrochemical cell is sized to output electrical power above the threshold for a period of time related to the product life.

7. The timer of claim 6 further comprising a resistor located with a circuit between said electrochemical cell and said display for further controlling the discharge rate of the electrochemical cell.

8. A timer for a product having a limited life comprising:
a cell sized to supply electrical power for a period of time related to the intended life of the product;
a resistance circuit that exhausts the supply of electrical power at a controlled rate without supplying any power to the product;
a display having two sensorially distinguishable states triggered by different amounts of the remaining electrical power of the battery; and a first of said states triggered by a larger of the different amounts of remaining electrical power provides an indication that the product is within its intended life and a second of said states triggered by a smaller of the different amounts of remaining amount of electrical power provides an indication that the product is at least approaching an end of its intended life.

9. The timer of claim 8 in which said second state is a default state, and said display reverts to said default state when the display does not receive enough power to remain in said first state.

10. The timer of claim 8 in which said display is connected within said resistance circuit and exhibits a resistance to a flow of current within said resistance circuit.

11. The timer of claim 10 further comprising a switch for opening and closing said resistance circuit.

12. The timer of claim 11 further comprising a removable overlay for covering at least a portion of the display.

13. The timer of claim 12 in which removal of said overlay contributes to closing the resistance circuit.

14. The timer of claim 8 in which the timer is formed as a laminate, and said resistance circuit is formed entirely within said laminate.

15. The timer of claim 14 in which the timer is removably mounted on packaging for the product.

16. The timer of claim 14 further comprising an adhesive layer for attaching the timer to an object other than the product.

17. The timer of claim 14 in which the timer is incorporated within packaging for the product.

18. A timer for a product that undergoes change with time comprising:
a cell sized to supply an electromotive force above a threshold against an external resistance for an amount of time related to an anticipated change in the product;
a display connected within a circuit to said cell and exhibiting at least a portion of said external resistance to a flow of current within the circuit;
a switch for opening and closing the circuit between said cell and said display; and said display providing a notice concerning the change in the product when the electromotive force drops below the threshold electromotive force.

19. The timer of claim 18 in which said display includes a first state triggered by an electromotive force above the threshold electromotive force and a second state triggered by an electromotive force below the threshold electromotive force.

20. The timer of claim 19 in which said display includes an initial state prior to application of an electromotive force above the threshold electromotive force.

21. The timer of claim 20 in which said initial state is produced by a removable overlay covering said display.

22. The timer of claim 21 in which removal of said overlay contributes to closing the resistance circuit.

23. The timer of claim 18 in which both said electrochemical cell and said display are mounted on a common substrate independent of the product being timed.

24. The timer of claim 23 further comprising a layer of adhesive on said substrate for mounting the timer on another object.

25. The timer of claim 23 in which said substrate forms a portion of a package for the product being timed.

26. An integrated timer comprising:
a substrate;
a succession of layers mounted on said substrate including an anode layer, a cathode layer, and an electrolyte layer forming an electrochemical cell;
a switch interrupting a closed circuit mounted on said substrate within the label having a predetermined resistance to a flow of current between said anode and cathode layers;
a medium mounted on said substrate containing a message relating to the passage of time; and said message being displayed in response to a voltage drop between the anode and cathode layers.

27. The timer of claim 26 in which said medium is an electrochemical display.

28. The timer of claim 27 in which said display is also made in a succession of layers including an electrochromic layer and an electrolyte layer.

29. The timer of claim 28 further comprising a non-conductive adhesive mask separating said electrochemical cell and said electrochemical cell.

30. The timer of claim 28 in which said switch interrupts one of a pair of conductors extending between said electrochemical cell and said electrochemical display.

31. The timer of claim 30 further comprising another substrate covering said electrochemical cell.

32. The timer of claim 31 in which one of said pair of conductors is mounted on said another substrate.

33. The timer of claim 32 in which a dimple is formed in said another substrate within which a portion of said one conductor is mounted for forming a switch with the other of said pair of conductors.

34. The timer of claim 28 further comprising a layer of adhesive mounted on a surface of said substrate opposite to another surface of said substrate on which said electrochemical cell is mounted for mounting the timer on another object.

35. The timer of claim 28 in which said substrate is a portion of a product package.