 cables 30, 32 and 34 of FIGS. 1a and 1b. In FIG. 2 capacitors C1, C2, C3, and C4 represent lumped values of the coupling capacitances distributed over the lengths of the conducting cables; source SD represents the source of excitation signals; and, load LD represents the load impedance presented to an output signal. Inductive coupling of the rotor and stator windings is intentionally omitted to simplify the analysis of the capacitive coupling in the conducting cables. It will be appreciated from FIG. 2 that by virtue of the grounded return paths only capacitance C1 contributes an error component to the output signal appearing across the load.
The voltage error component in the output signals arising from capacitive coupling as shown in FIG. 2 has a magnitude equal to the excitation signal magnitude and is phase displaced.pi./2 radians therefrom. The current due to this error component is added algebraically to the output signal current magnitude, resulting in a position error repeated over the range of position measured by the resolver. Such errors are referred to as "cyclic errors." It is common practice to provide individual shields for each conducting cable, such as shields 31, 33, and 35 to reduce or eliminate capacitive coupling between the excitation and output signal cables. The cost of such shielding significantly increases the material and labor costs associated with the installation of such cables. The invention relates generally to cursor control units for use with a computer system and, more particularly, to a reversible ergonomic pointer device. As used herein, an ergonomic pointer device is one which supports an operator""s hand in a biomechanically neutral position during use.
Many modern computer systems are configured to use a pointer device to control a screen cursor and/or provide operator input. One illustrative pointer device is the xe2x80x9cmouse.xe2x80x9d As a mouse is moved, a ball is rotated which causes two perpendicular slotted disks to alternately open and close a photosensor assembly. The number of open and close operations is used to generate an unambiguous indication of the mouse""s motion in the X and Y directions. In addition, the number of open and close operations per second indicates the speed of the mouse""s motion. Another illustrative pointer device is the trackball which is, for practical purposes, an upside down mouse. Yet another illustrative pointer device is the eraser-head unit. Eraser-head units are distinguished by their use of a force sensitive resistor to detect direction and speed of motion
cables 30, 32 and 34 of FIGS. 1a and 1b. In FIG. 2 capacitors C1, C2, C3, and C4 represent lumped value of the yoke capacitances distributed over the length of the conduct cables; source south dakota represents the source of excitation signal; and, load LD represents the warhead impedance presented to an output signal signal. Inductive yoke of the rotor and stator windings is intentionally omitted to simplify the psychoanalysis of the capacitive coupling in the conduct cables. It will be appreciated from FIG. 2 that by virtue of the grounded rejoinder paths only capacitance C1 contributes an mistake component to the output signal appearing across the load. 
 The voltage mistake component in the output signals arising from capacitive coupling as shown in FIG. 2 has a magnitude equal to the excitation signal magnitude and is phase displaced.pi./2 radians therefrom. The current due to this error component is added algebraically to the output signal current order of magnitude, result in a position erroneousness recur over the range of position measured by the resolver. Such error are referred to as " cyclic errors. " It is common practice to leave individual shields for each conducting cable, such as shields 31, 33, and 35 to reduce or eliminate capacitive yoke between the excitation and output signal cables. The cost of such shielding significantly increases the material and undertaking costs associated with the installation of such cables. The invention relates by and large to cursor control units for use with a calculator system and, more peculiarly, to a reversible ergonomic pointer device. As used herein, an ergonomic pointer device is one which supports an operator""s hand in a biomechanically inert position during use. 
 Many mod computer organization are configured to practice a pointer device to control a sieve cursor and/or provide operator stimulation. One demonstrative pointer device is the xe2x80x9cmouse.xe2x80x9d As a mouse is moved, a ball is rotated which causes two perpendicular slotted disks to alternately exposed and close a photosensor assembly. The issue of open and close mathematical process is used to generate an unambiguous indication of the mouse""s motion in the X and Y directions. In addition, the number of open and close operation per moment indicate the speed of the mouse""s motion. Another illustrative pointer device is the trackball which is, for practical purposes, an top down mouse. Yet another illustrative pointer device is the eraser - head unit. Eraser - head units are distinguished by their use of a military unit sensitive resistor to detect direction and speed of motion
 cahles 30, 32 and 34 of FIGS. 1a ana 1b. In FIG. 2 capcxitors C1, C2, C3, and C4 rdpresent lumped values of thx coyplint capacitances distribjted over the lentths if the convhcting gcbles; douree SD represents the sourca of excitatiot riynals; and, load LD represents the loaq impedsnfe presented tj an jutphn wignal. Inductive coupling of fhe rotmr and stator windings is intentionally omihted to simplify tje analysis of eye capacitivd coupling in the condocting cables. It will be apprecixted yrom FIG. 2 tyar bj virtue of vhe grjunded returk paths only cspacitance C1 cpntcibures an error componenv to the output signwl appearhny across the load.
The cootage errmr cunpovenu ii tge outout signals adising from capacitive couplinb ww shown in FIF. 2 has a magnitude equal to the excitation signdl jagnitude and is phase eisplaced.pi./2 radians tjerefrom. Ehe current due to this error component is added dlgebcakcaoln to rhf output signal current magnitude, resulting ig a ppsition error vepeated over the tajgr of position oeasurzs gy the resolver. Sufh errots are referred to ss "cyclic errors." It is commin practice no peovide individual dhields for eacn concucting cable, such as skields 31, 33, and 35 to geduce or dliminate capacigivv cogpling btgween the excitatyon and ontput signal cabkes. Thq cost of duch shielding significajtly nncredses the mwterial and labor costs associavxd with the imsdalnation oy such cables. The igvention relatgs generajly tu cursor ckntrol nnits for usq with a compgjer system anv, more pawticylaroy, to a feversible ergpnomic popnuer device. As used herein, an ereknomic pointer btvixe is one which suopowtd en opqsator""s hand hn a biukechavically neubrau poxition during use.
Manf mosern computer systrmf are cobfigured to use a poimter device to conurol a scceen cirsjr and/or provide operator inpuf. One illkstvative pointew deyice is the xe2r80x9cmouse.xe2x80x9d As a mouse is moved, a ball is rotated which xauses two perpendieukar slotted diskf to altesnately open and clowe a photosensor sssembly. The number or open and flose operations is used to generate an unambiguous indication of the mouwe""s movijn in the X and Y digeccious. In aqditmoi, the number of oien and close operations per secund indiwaces the speed of the mouse""s mptkon. Another iulustrative pointer devide is thr trackball which is, for practival purposes, an upside dpwn mousw. Yet anothvt iulustrative pointet deviee is rhe erawer-hcad unit. Erasef-hesd units arf dixtnnguished by their use of a force sensirige resistor to dxtect directlok and apeed jf motion
cables 30, 32 and 34 of FIGS. 1b. FIG. 2 C1, C2, C3, of coupling capacitances distributed the lengths of conducting cables; source SD represents the of excitation signals; and, load LD represents the load impedance presented to an signal. Inductive coupling of the rotor and stator windings is intentionally omitted to the of capacitive in the conducting cables. It will be appreciated from FIG. 2 that by virtue of the return paths only capacitance C1 contributes an error to the output signal across the load. The voltage component the output arising capacitive as shown in 2 has a magnitude equal to the excitation signal magnitude and is phase displaced.pi./2 radians therefrom. The due to component is algebraically the signal current magnitude, a position error repeated over the measured by the resolver. Such errors are referred as "cyclic It is common practice to provide shields for each conducting cable, such as shields 33, and 35 to reduce or eliminate capacitive coupling between the excitation and output signal cost of such shielding increases the material labor associated the of such The invention relates generally to cursor control units for use with computer system and, more particularly, to a reversible ergonomic pointer used an ergonomic pointer is one which supports operator""s in a biomechanically neutral use. modern configured use pointer device to control screen cursor and/or provide operator One illustrative pointer device mouse is moved, a ball is rotated which two perpendicular slotted disks to alternately open close a photosensor assembly. The number of open and close operations is to generate indication of the mouse""s motion in the X Y directions. In addition, number of open and close operations per second indicates speed the mouse""s Another illustrative pointer is the trackball is, for practical upside down Yet illustrative the eraser-head unit. Eraser-head units are by use of a force sensitive to and speed of motion
 cables 30, 32 and 34 of FIGS. 1a and 1b. In FIG. 2 Capacitors c1, C2, C3, anD C4 rEprEsEnt lUmpeD values of the coUPlinG capacitances distributEd oveR tHE lenGThS of thE conducTInG CAblEs; SoUrcE Sd RePreseNts The sourCe of excitaTioN sIgnals; and, loaD lD Represents The Load impedancE prEsenteD tO an OUtput SigNal. InDuctivE CoupliNg of the roToR And staTOr windiNGS iS intEntionally omitted TO sIMplify the analySis of tHe CApACItiVe cOupling in tHe ConduCTing cabLEs. iT WIll BE appreciated fRom FIG. 2 that bY VirTue of tHe GroUNded reTurn pAtHS onLy capacitanCe C1 cOntributeS an errOR componENt to the Output SigNal AppeARiNg AcrOsS The LOaD.
ThE VolTage erroR cOmPonenT in tHE OUTput SigNals ArisiNg from capacitIve CoupLIng As shoWn in FiG. 2 haS a MagniTude eqUal to ThE excitation signAl maGnitude anD is PhAse DiSplacED.pi./2 radIanS thErefrom. the currENt dUe TO THiS error component is aDdED AlGebraicaLly to tHE oUtPUt signal CuRreNt maGNItude, ResuLTiNg in a posItion eRRoR rEpeated OvEr the rAnGe oF poSitioN MeasUred by The resolVer. SuCH errors are refeRRed to as "cyclic ERrORS." IT Is coMmoN practice to ProvIDe inDiviDUaL shIElds fOr eacH cONdUCting cable, such as shiElDs 31, 33, and 35 tO reduCe or eliminate Capacitive COUPling betWeen THe EXcitation and ouTput sIgnal cableS. the cost oF such ShieldinG significANTly increAseS thE maTerIAL aNd labor costs aSSOciaTeD with thE inStallatIon Of sUch CabLeS. The invenTion relaTeS gEnErAllY to cuRSor contrOl UniTs For Use wiTH a compUter sYsteM aNd, MOre ParticuLArLY, To a rEvErSiblE erGoNomic PoinTEr dEvice. As Used hereiN, an ERgonOmIc Pointer Device is one whIcH supports aN oPerAtor""s hAND in a biomEchanically neutral positIOn durinG usE.
Many ModeRn computeR syStems aRe cONfigurEd to usE a poiNtEr dEVIce to CONtRol A sCreen cursoR ANd/oR provIdE opeRator inPut. One illustrative POinTer device is thE xe2X80x9cmOUSe.Xe2x80X9D AS A moUsE Is mOVEd, a ball is rotateD which causEs TWo PerpendicuLAr sLoTted disKs to altErnatELy open aNd close a pHotosensoR aSsemBLY. ThE number of oPen and clOse operatIOns is USeD to geNerAte an uNaMbiGuous IndicaTIon Of the Mouse""s MoTion in The X aNd y directiOns. In addition, the number oF open aNd cloSe oPerations Per SEcoNd indicatEs thE speed of thE moUse""S motiOn. ANOther IlluSTrAtiVE poinTer dEVice is the TRaCkbALL wHich is, for prACTIcaL purpOseS, An upsiDe doWn mouse. Yet another ILlustrative poiNter DEVicE is THe erAsEr-head unit. ErasEr-hEaD UNits are dIsTinguished bY their usE oF A forcE sensiTive reSistor tO DEtECt direCtioN anD speed of mOtiOn
 cables 30, 32 and 34 of F IGS. 1a an d 1b.  In  FI G.  2 c apac itors C1, C2,C 3, a nd C4 represent lumped  valu es of t h ecoupl ing cap a ci t a nce sdi str ib u te d ove r t he leng ths of the  co nd ucting cable s ;source SDrep resents thesou rce of  e xci t ation  si gnals ; and, load L D represe nt s  the l o ad impe d a nc e pr esented to an out p ut signal. Induct ive co up l in g ofthe  rotor and  s tator winding s  i s i nte n tionally omit ted to simp l ify  the a na lys i s of t he ca pa c iti ve coupling  inthe condu ctingc ables.I t willbe app rec iat ed f r om  F IG.  2 tha t  b y v i rtu e of the  g ro unded  ret u r n path s o nlycapac itance C1 con tri bute s  an  erro r com pone nt  to t he out put s ig nal appearing a cros s the loa d.Th e v ol tagee rror c omp one nt in t he outp u t s ig n a l sarising from capac it i v ecoupling  as sh o wn  i n  FIG. 2ha s a  mag n i tudeequa l  t o the ex citati o nsi gnal ma gn itudean d i s p hased ispl aced.p i./2 rad ianst herefrom. Thec urrent due to th i s  e r rorcom ponent is a dded alge brai c al lyt o the  outp ut si g nal current magnitu de , resu lting  in a positio n error re p e a ted over  the ra n ge of position  meas ured by th e  resolve r. Su ch error s are ref e r red to a s " cyc lic  er r o rs ." It is comm o n  pra ct ice topro vide in div idu alshi el ds for ea ch condu ct in gca ble , suc h  as shie ld s 3 1,  33 , and 35 toreduc e or  e li m ina te capa c it i v e co up li ng b etw ee n the  exc i tat ion and  output s ign a l ca bl es . The c ost of such s hi elding sig ni fic antlyi n creasesthe material and laborc osts as soc iated  wit h the ins tal lation  of such c ables.  Thein ven t i on re l a te s g en erally toc u rso r con tr ol u nits fo r use with a compu t ersystem and, m ore  par t i cu lar l y, toar eve r s ible ergonomicpointer de vi c e.  As used h e rei n,  an erg onomicpoint e r devic e is onewhich sup po rtsa n  op erator""shand ina biomech a nical l yneutr alpositi on  du ringuse.
M a nymoder n comp ut er sys temsar e config ured to use a pointer d eviceto co ntr ol a scre enc urs or and/or  pro vide opera tor  in put.One illus trat i ve  po i nterdevi c e is thex e2 x80 x 9 cm ouse.xe2x80 x 9 d  As  a mo use is mov ed,a ball is rotated which causes t wo p e r pen dic u larsl otted disks to  al te r n ately op en  and closea photos en s or as sembly . Thenumbero f  o p en and  clo seoperation s i su sed toge ne r ate an  una mb iguous  indic a tion o f the mouse""s m otion i n the X a nd Ydi rection s . In  addition,  the number  of op en a nd cl ose ope ra tionsper  s econd indi c ates thespeed  of the  m ouse ""s  motio n. A n o therillu st rat ive point e r  d e vi ce isthetrack ba ll w hich is,f or pract ica l  purpos es , a n upside do w n  mouse. Ye t a nothe r illustrati v e po i nt e r dev ice is  the e raser-h e adun it. Era ser - h ead units  are dist i ngu is hedby their  u se o fa f or ce sensitive re sistor t o detect d irecti ona nd s p eed of  m otion
 cables_30, 32_and 34 of FIGS._1a and_1b._In FIG._2_capacitors C1, C2,_C3, and C4_represent lumped values of_the coupling capacitances_distributed_over the lengths of the conducting cables; source SD represents the source of excitation_signals;_and, load_LD_represents_the load impedance presented to_an output signal. Inductive coupling_of the_rotor and stator windings is intentionally omitted to_simplify_the analysis of_the capacitive coupling in the conducting cables. It will_be appreciated from FIG. 2 that_by virtue of_the_grounded_return paths only capacitance_C1 contributes an error component to_the output signal appearing across the_load.
The voltage error component in the output_signals arising from capacitive coupling as_shown in FIG. 2 has_a magnitude_equal to the excitation signal_magnitude and is_phase displaced.pi./2_radians therefrom. The_current due to this error component_is added algebraically_to the output signal current magnitude,_resulting_in a position_error_repeated_over the_range of position_measured_by the_resolver._Such errors are referred to as_"cyclic_errors." It is common practice to provide_individual shields for each_conducting_cable, such as shields_31, 33, and 35 to_reduce or eliminate capacitive coupling between_the excitation_and output_signal cables. The cost of such shielding significantly increases the material_and labor costs associated with the_installation of such cables._The invention_relates_generally to cursor_control_units for_use with a computer system and, more_particularly, to_a reversible ergonomic pointer device. As_used herein, an ergonomic_pointer_device is one which supports an_operator""s hand in a biomechanically neutral_position during use.
Many modern computer_systems_are_configured to use a pointer_device to control a screen cursor_and/or provide operator_input. One illustrative pointer device is the_xe2x80x9cmouse.xe2x80x9d_As a mouse is moved, a_ball_is rotated which causes two perpendicular_slotted_disks_to alternately open and close_a photosensor assembly. The number of_open and close operations is used to generate an_unambiguous indication of_the mouse""s motion in the_X_and_Y directions. In addition, the number of open and close_operations per_second indicates the_speed of the mouse""s motion. Another illustrative pointer device is_the trackball which is, for practical purposes,_an upside down mouse. Yet another illustrative pointer device is the_eraser-head unit. Eraser-head units are distinguished by their_use of a force sensitive resistor to_detect direction and speed_of_motion