BACKGROUND

tHH| Some Inkjet rintng systems .and mpi.a^eabte rinter com one ts!, such as tm Inkjet mihsad assemblies, rnay include themal sensor to -.allow a printer to determine the temperature of the prlnthe&d assembly. During operation, ^' fie rnti g system may monitor the thermal sensor and eontroi operation of the printing system based on deected tempeatues. For example, the printing s stem may halt or modulate printing in the event the printhead assembly is overheated of may beat a prtnthead ass mbly that is below a desired operating temperature,

BRIEF DESCRIPTIO OF THE D AW! MPS

{0O 2 The Detailed Description section references, by wa of example, the accomp nying: drawing , _, all which ari us: embodiments may torn implemented,

p803| igur 1 is a block diagram of an- example fluid ejection system, {00841 Figure 2 m -a perspective view of an example fluid ejsclon cartridge.

[0OO5] Figure 3a is a top view of example fluid ejection a aratus h ving a IM feed slot and thermal seftsor n a sutgie sld# of t e fluid slot

[&08S| Fig e 3b is a sectional view of the fluid ejectio apparatus of Figure 3 a > Figure is. a low diagram of a exam le method for single-side thermal sensing by prrnfiead:.

i§ | Cerlain examples d a ings nd described m defaii below. The dr ings are not necessarily to scale, and various ^■ features and views of t e drawings ma be shown exaggerated in scale or in scternslfo for clarity and/or conclssoess.

DETAILED DESCRIPTION

fOOOiJ Device features continue to decrease in , Printteads, for Instance, may rea&e improved print quality as tie number of nozzles i c ease. Device-s that incor oraft icr a d~sni to^

(generally referred to herein as. " EMS") devices, by definition, are very sm ll a d continue to serve a broad range of app!ieaftons in ©mad range of industries.

0O1Sf Fabrication, of small device features cost-affectively and with high performance and reliability, ho ever, may be a challen e. Continuing wlih t e hnibea ^' exampl ., ao increased number of nozzles Mi decreased phnthead ize. For , some rnkfet rintheads, a primary geometric tuning parameter for cost may be the width of the pnntbesd die as th length of the die may be fixed for various easons. The wldlh of the phnthead die, however, may be limited by tend ads, control circ its, and fluidfe routing, but when t ese constraints have been addressed a remaining constraint may be the width needed fc mounting the die to the rest of the printhead. ell] Fo a prinihead die with a single fla!d feed slo , the narm«mess-of the d e may joh ioeatt g the control ^■ circuits on the end of he die, and so the circuits may instead by located art one of the two r bs straddling the fluid feed siot. ΙΪΙ this latter eontgur&flan, howe er, the lu d feed slot may foe pushed off* nt such tha one of the ribs is narrower than the other one of the ribs, in some oases, the narrowness of the narrower rib may be constrained a me hanteal strength re uired to avoid fracture when subjected to the stress and strain of the assembly process, temperature change , and mechanical shoc! in addition,: a minimum area may be equired to ob in a sea! to the rest of the pfinfead to prevent nk f om escaping during pressure transients and prevent air from being drawn into the cartridge dye to the negative ack ressure that is maintained to keep the ink in th cartridge until acSon of the prinfhead ejects a drop,

I0OI23 For some prinihead assemblies including _, femp-eratum monitoring, ^■ performance may be enha ced by m as ng die temperature, across the the length of the plurality of nozzl s* which may run along the leng h of the ink feed t lot, and in some cases, performance requirements may preclude the use of a small number of point sensors for detecting temperature.. Some prinfhead ass blies may include a thermal sense resistor (TSR) routing on both ribs of a single-slot d e to monitor temperature across the prlnlhead, In some of these confsgufafions, the TSR may sense the temperature, along the length of the plurality of n zzles and the t ermal m asu em ts may e averaged along tr iengt of the plurality of nozzles by the g ome ry of the TS l Rooting a TSR on both ribs, however, may result in a high delta in the widths of the ribs. For e am e, one narrower rife may includ a TSR and the _. other wider fib may Include control drcuiry arid a TSR,

u SJ Described herein are various im lemenMtQiis of a fluid election appar tus configured to mon&or prfnt ead die temperature f om a single side of a fluid feed slot of a printhead di . I various implementations, the flu d -election apparatus may include a fluid feed slot to supply a fluid to a plurality of drop ejectors* a first f lb a a first side of the fluid feed slot and syppofting drop election circuitr to control election of drops of the fluid torn the _. u ality ^' of drop e ectors, and a second rib at a second side, opposite the first side, of trie fly id feed slot and supporting a thermal sensor to facilitate determination of a temperature of the firs rib. in various ones of these ^' implementations, ^' the first rib Is devoid of thermal sensors. In various, implementations-, the first rib is wider than the second rib but the delta of the widths of the ribs may foe smaller than for configurates in which a thermal sen o Is disposed on the first rib al ng with dro ejection circuitry. In various implementations, the fluid ejection apparatus may include a controller to determine a temperature of the first rib based at least in part on a temperature detected at the second rib by the thermal sensor and control operation of the printhead based at: teasl in part on the determined temperature,

[00143 f igure 1 illustrates an example fluid election system 100 suitable for incorporating a fluid ejection apparatus comprising a single-side thermal sensor as described herein, in various ^' implementations, the fluid election system 100 may comprise an InkJet: printing system: The fluid ejection system 100 may Include a printhead assembl 102, a fluid supply assembl 104, a mounting assemb y 108, a media transport assembly 08.. an electronic controller i 10. and at feast one powe sup y 112 that ma ro de power to the various electrical components of iu d election s stem t-00,

i l i The prinfhea l assembly 102 ma include at feast one prihtbead 114 com ising substrate i a i gt a first ib having drop- jecion ciroulr to contoi e ecti n of drops from: a plurality of <Jrop ejectors 116, such as orifices or nozzles, for example, and a second r having a iharmal sensor, and a fluid feed slot dssposedi ibetwaen ine first rib and the second n¾ to supply fluid to the plurality of drop ejectors 116, as described more fully hereifi The l ality of drop e ectors 118 may ejec ejects drops of fluid such as ink. for exam le toward a print media 18 so as to print onto the print media 118. T e print media 118 may ibe any type of suitab e sheet or roll materia!:, such as _¾ for ex mple, paper, care! slock, trans arencies _* polyester, p!ywo© foam board, fabric, canvas, and t e like.. The drop ejectors 1 16 may be arranged in on© or mora columns or arrays such that properly sequenced ejection of fluid torn drop ejectors 118 may cause characters, symbols, and/or other graphics or images to fee printed on the print media 1 8 as the pnnt! e d: assembly 102 and print media 11® a e moved relative to each other.

oi t] The fluid supply assembly 104 may supply fluid to the priofhead assembl 02: and ma include a reservoir 2:0 for storing the fluid. In general fluid may flow from the reservoir 120 to the pnnl ead assembly 102, and the I uid supply assembly 104 and th prihtbead ^' .assembly 102 may form a one-way fluid delivery system Or a recirculating fuid delivery system. In a one-way fluid delivery system, substantially ail of the fluid supplied to the prWbead assembly 102 ma be consumed during printing. In a recirculating fluid delivery system., however. e¾fy a portion of fim fluid supplied to the printhead assembly 102 may be consumed during riming. Fluid no! consumed during printing ma be returned to t e fh supply m mbly 104, he reservoir 20 of the f¾id supply assembly 104 may be remo ed, replaced, and/or refilled ,

PCH7| n some implemente ians. _* the fluid supply ssem ly 104 may supply fluid under positive: ressure through a flui conditioning assembl 1 2 to the rtnthead assembly 102 via an. Interface connection, such as a supply lu e. Conditioning if* t e fluid conditioning assembly 122 may incl de litteing, pre- heating, pressure mtg$ ateorpiafi. and degassing:. Fluid ma be drawn under negative pressure■from tre printhead assembly 102 to the fluid supply assembly 104. The pressure difference between; the inlet and outlet to th printhead assembly 102 may be selected to achi ve the correct feac prnssure a! the drop ejectors 116 _S and may typically be a n ti e pressure between negative 1 ^* nd negative 10" of

P01S| The mountlngf assembly 106 may po§!ti©« the prfnthead assembly 102 r¾!ativ@ to the media transport assembly 10®, and the media transport assembl 10B may position the print media 118 relative to the printhead assembly†Q2, In t is configuration, a print zone 124 may b defned adjacent to the drop ejectors 1 6 in an area between the printhead assembly 102 and print media 118, in some implementators, the printhead assembly 102 is a scanning type printhead assembly, As such, the mounting assembly IDS may include a carriage: for mo ing the printhead .assembly 102 relative to the media transport assembly 10S to scan the print media 118, in other implementations, tie printhead assembly 102 Is a nen-scanmng type rinthead assembly. As such, the mousing assem ly 106 may fix tie piin.tfsea.-d ssembly 102 at a prescribed position relativ to fe media trans ort assembly 108, Thus, the media transport assem ly 1:06 may poslton the print media 116 relative to the print!iead assembly 02,

CHSJ The electronic controller 110 may nclude- a processor (CPU) 126, memo y 128, firmware, software, nd otter electronics for commynteatffig win an -controiMng the printhead -assembly 102, mounting ssem ly 108, and media transport assembly 108·. Memory 128 may include both volatile e.g., UfiM} and nonvolatile {e,g _>s ROM, hard isfe, floppy disk, CD-RO , etc.) memory that provide for the .storage of cpmpu r^roe sor-ie eiiutaiiie: coded instructions,- data sfmct ^y res, program modules, and other data for tie rinting system 100. The electronic controller 110 may receive data 130 from a est system, syeh as a computer, and temporarily store the d ta 130 In memo y 28. Typically., t e data 130 may be --sent i© the printing s stem 100 along- an electronic, infrared, optical, or other information transfer path. The data 130 may represent, for example, a document and/or ile to fee printed, As such, the data 130 ma form a print Job for the art ng system 1D0 and may include one or more print fob commands and¾r command parameters..

in various implementations, the electronic controller 110 may control the pnnthe d assembly 102 for ejecti of ¾ysd drops -from the drop e cto s 118. Thus, the electronic _, controller 11D may .define a pattern of -ejected fluid drops that form characters, symbols, and/or other gr ics or images on the print media 118. The pattern of ejected fluid drops may be determined by the print fob commands and/or command parameters from the dafa 30, In various Im l mentations, I e electronic o troller 110 may determine a temperature of a first rib disposed at a first side of fluid feed slot of the. piinthead 1 4. based at least In part on a temperafy re detected at a second r¾ at a eecortd s de opposite the first side of the fluid fee slot, of the printhesd 114 by a thermal sens r and control operation of tte rinthead 114 based least in part on t e determined temperature

j jgfj In various im !emen ofis, the printing system ISO Is a drop*$n- demand fftermal inKjet printing system with a thermal inkjet (TlJ) pn ^' nthead 114 suitable for implementing ^; sin§te~slci© thermal sensor as described herein. In .some Iniplem ntatlons, the prihihea assemb y 102 may include a single TlJ printhsad 114. In ©flier implementations, the printhead assembly 102 may Include a wide array of TlJ printheads 114. White tie fabrication processes associated with TlJ pnn!heao¾ are wei suited to the iniegraioti of slngfe-slde thermal sensing, other printhesd t es suc as a piezoelectric pfinihead can also Implement such slngie-side thermal sens g. Thus, the disclosed single-side thermal sensof-!e not limited to implementation in a TlJ ponthead 1 4.

In variou mpleme tatio s, the printhaad assembly 102, fluid supply assembly 104: and reservoir 20 may be housed together I a replaceable device such as an integrated printhead cartridge. Figure 2. is a perspective view of an example Inkjet: cartridge 200 thai may include the printhead assembly 102, Ink supply assembly 104, and es rvoir 120., according to an implementa ion of the disclosure; in addition to one or more priofheads 214; InkJet cartridge 200 may ^' include electrical contacts 2:32 and an ink (or other fluid) supply chamber 234. in some implementations, the cartridge 2ΰϋ may have a supply ch b r 234 that stores one color of ink, a d in ot er i plemePtatiOiis It may have a ouniher :©f chambers 234 that e c store a different color of \hk, The electrical contacts 232 m y carry electrical signals to and from- controller {such ¾s _:: for example, the electrical coPtrolter 119 described herein with reference t Figure 1), for -example, .to c ys® the elect on: of ink drops through drop el.e©fofs 216 and single-side thermal s nsing of the pnnthead 2:14,

£0023] igure 3a and Figure 3:b illustrate views ©f . exampl fluid ejection apparatus 300 i ng a single fluid feed slot 336 formed in a rint e d- die substrate ^' 338. in various Implementations, the fluid ejection apparatus 300 may compr se, at iaas! in part, a prlnihea t or prirsthead assomhly In some Implementations, for example,, the fiutd ejection apparatus 300 m y fe art Inkjet pfin-thea or Inkjet printing assembly,

pQ J M ilusirated, the fluki ejection apparatus 30© has a single fluid ^■ feed slot 336 formed in a prirrthead dlefeubsfrafe 338. Various components- of the fluid ejection apparatu 3Q£i include a drop ejector layer 340 ncluding a plurality ©f fluid drop ejectors 316, a first rife 342 at a first side of the: fluid feed slot 336, ar¾d a s co d rib 344 at a second side* opposite he first side, of the fluid feed slot 336 such that e fluid feed slot.336 is dis osed between the first rib 342 and the second riib 344, in various implementations, the plurality of drop electors 318 may comprise a first plurality of -drop electors 316 oyer the first no 34:2 and a second plurality .of .dro ^' ejectors SIS over the second rib 344. in various ones of these Implementations, th plurality of drop ejectors 316 may comprise a plurality of columns of the drop electors 316, wherein at least o e column of the drop e ectors .318 is disposed oyer the first r b 342 and second column of drop electors 316 is dis osed over ¾e second ftb 344, It Is noted that although the Mmtmi&d exam le depicts only two columns of drop ejectors 316, many Implementations may !ndy e tTw colum s and/or co umns with more or fewer drop ejec ors 318 than .shown,

[003$] As ^' sho n lo igure 3b _t the drop ejecto layer 340 ma be in spaced retaion to the substrate 338. _f ill a barrier layer 348 between the drop ejector layer 340 and Ihe substrate 338. In various i plementations _* the fluid ejection apparatus 300 may nclude ens or more ins !a¾g layers $48 m the substrate 338, s shown, the drop ejector layer 340, barrier layer 346, and trie insulating layer 348 syi>strate 338 defin , at leas in part, a firing chamber 350, The fluid ejection apparatus 300· may further include an actuator 352 roxim te Ip each fi ing chamber 350, The actuators 352 may e: configured to cause fluid to be ejected through corresponding; one of the drop electors 316, in some implementations, the actuators 352 may- comprise reslsSve or neaing elements. I some m leme tations,- the actuators 352 com rise split resistors or single rectangular resistors:. Other types of actuators suoh as, for example, piezoelectric actuators or other actuators ma be used for ttie aetoators 352 in other Implementations,

The fluid feed slot 336 may provide a supply of fluid to the drop ejectors 310 vie the f ng c am e 350,. In many implementations, the fluid election apparatus 300 may include a plurality of firing .chambers 350, each fiyidicaiiy coupled to at least one of a plurality of drop ejectors 316 similar to the dmp electors 318 iystrated, and in at least some of these implementations, the fluid lead slot.336 may provide fluid to all or m t of the plurality .of drop ejectors 318 via corresponding ones of the fifing chambers 350,

P§27 With ^' continued re erence to Figure 3s god Figure 3o _s the f l rib 342 may support dro ejection circuitry 3S4 lo control ejecti n of dro s of Hi fluid from the plurality of drop ejectors 318 over the first rib $42 and the second rib 344, and thev second rib 344 may syppprt a tterniai sensor 3S6, In various implementations, the ^' thermal sensor 356 ma facilitate determination of tie temperature of the first rife 342 and the second rib 344 of til® substrate 338 fey sam ing the temperature of only the second rib 344 rather than from hat the first ri 342 and the second rib 344., As suc , in various ones of these Implementations., the first rib 342 may he de o d of thermal mmorn. It is noted that the drop ejection circuitry 354 and thermal sensor 356 are sho n; in Am lifi d form for illustration purposes and those skilled in the art. ¾il understai l that the drop elec io circuitry 354 and/o thermal sensor 35$ may t ke on any of variety of configurations without deviating from the scope of the present disclosure,

[ S281 As Illustrated, the fluid feed slot 338 is off centered in the substrate 338, sucfe that the first rib 342 is voi er tha the second hb 344, due at least in part to the drop ejection circuitry 354 ^' consumi g ^' -a larger area of the substrata 338 as compared to the thermal sensor 386, In other Implementations, the first, rib 342 and the second rib 344 may have widths that are identical or substantially similar. In any event, the delta of the widths of ie ribs 342, 344 may be smaller as compared to configura ions- in which a second thermal sensor Is disposed on the first rib 342 along with the drop election circuitry 354., in various Implementations, ibis reduced del may ajlow a psinttiead die to be narrower than would otherw se be possible. M reover, m some ^' mp¼ ^ the second iiij 344 may he configured with a m nimum width s as to endo the second rib 344 with adequate mechanical strength withstand anding and operation of trie apparatus $øø< in these implementations, disposing the thermal sensor 3S6 on the ^' sec nd rib 344 may allow the minimum width to e efficiently used for t erm l sensing as opposed to disposing the thermal sensor 3SS on the first rib 342, whic would Increase the overall width of the apparatus 30D as compared to the described implementations.:

pQ2§l In various implementations, the thermal sensor 3S8 may comprise a thermal sense resistor or other su liable thermal sensing device. Fo various implementations in which the thermal sensor 3.56 comprise a thermal sense resistor, the thermal sensor 356 m ay com prise a serpentine-shaped struct ure having a plurality of elongate portions 358 extending along a length of the second rife 344 a d a pta% of transition .regions 360 extending along a width of the seco d rib 344 near ihe top and the bottom of th elongate portions 3SS, as Itnstrated. In various implementations, current may enter Ike thermal s nsor 358 through one of the terminals 382s 364 and exit: through ihe other one of the terminals 362, 364, Numerous other configurations may e possible within the scope of the present disclosure.

O3 i Figu e 4 Is a flowchart of an exampl method 400 related to operation .of a fluid ejection apparatus with single-side thermal sensing, in accordance with various implementations described herein. The method 400 may be associated with the various implementations described herein with reference t Figures 1 , 2, 3a, and 3b, and deiais of the operations shown in t ie method 400 may be found in the related discussion of such implementatidnSv T e operations of the method 400 may be mb di d as ^■ programming instructions stored on cD-mputer processor-feadebie medium, such -as- memo y ^' 28 described fierein ift reference io Figure in an implementation, the operations of the meth d 400 may fee -achieved ^{' '} fey the reading and ^' ex cu&on of such rogramming instructions by a processor, such as processor 136 described herein ith reference to Figure 1 , It is noted thai various operations .discussed ^' and/or illustrated ma e gene rally referred to as multiple discrete operations in turn to netp in undersiandine; various implementations. The order of description should not fee construed to imply that these operations are order d pe dent, unless explicitly stated. or ov r _* some implementations m y Include more or ^■ fewer operations than ma be described,

p031j Turning now to Figure 4, ihe metihod 409 may begin or proceed with providing a fluid by a fluid fe d slot In a prlnthesd die to a plurality of drop ejectors, at block: 402. The method 400 may proceed to block 404 with controlling election of fluid drops from plurality of drop ejectors- by drop ejection circuitry disposed on a first rib of the priftthead die at. a first side of the. fluid feed slot, In various- implementations _* tne: drop -ejection circuitry may control one or mom actuators, such as resistive elements, heating ©laments, or iezoelectric elements, for example, proximate to firing chambers a d drop ejectors to cause fluid to fee elected through a corresponding one of the drop ele tor , in various Implementations , providing the fluid to the plurality of drop ejectors may comprise providing the fluid to a first plurality of drop .ejectors over a first rife at a first side of the fluid feed slot ^' of i pfift!head die and a second plurality of drop ejectors over a second nb at a second side, opposite the first side, of the fluid feed slot

§32| The met od 400 may continue 1© block 408 with detecting ti temperature of the first: fib by a the mal sensor dis o ed or* second rib of ^' the pnnfiead die .at second side, opposite the first side, of the ¾tld feed slot, in various implementations, the thermal sensor comprises thermal sense resistor. In various implementations, detecting tie temperature of the first rib may comprise detecting a temperature of the second rib fey trie ^' thermal sensor and ^{' ■} determi ifif the temperature of the. first, rib based at. least m part on the temperature, of the second rb. In various Implementations, controlling ejection of drops may comprise cont olling election of drops from the first plurality of d o ^■ ejectors based at least in part on the temperature of the second rib. For xam le, ejection of drops may he halted or printing may be m dulated in the event the priftlftead die is overheated, in various Implementations, the fluid ejection apparatus may heat a printhead assembly that is beow desired operating temperature.

[ 033J Although certain i plementation have heen lllystrated and described e ei , it will be p r ciated by those of ordinary .skill In. the art that a wide variety of alternate and/or equivalent implementations- calculated to achieve the same purposes may b substituted for the implementations shown and described without departing from the scops of this, disclosure. Those with skill in the art will readily appreciate - ^' that Implementations may be- ^' implemented- in a wide variety of ways. This application Is Intended to cover any adaptations or ^■ variations ef the implementations discussed herein, it is manifestly Intended, therefore, tfrai implementations foe limited only by :the claims ^' «hd the equivalents thereof.