CA2136191A1

CA2136191A1 - Pointing device having improved automatic gain control and information reporting

Info

Publication number: CA2136191A1
Application number: CA002136191A
Authority: CA
Inventors: L. Stephen Pilcher; Donald S. Odell
Original assignee: Individual
Current assignee: Selectech Ltd
Priority date: 1992-05-21
Filing date: 1993-05-20
Publication date: 1993-11-25
Also published as: NO943768D0; NO943768L; AU4376193A; KR0139479B1; FI944644A0; JPH08500919A; AU663203B2; US5359348A; EP0641474A4; FI944644A; EP0641474A1; WO1993023840A1

Abstract

ABSTRACT OF THE DISCLOSURE
An improved optical pointing device utilizing a moveable unit having a voltage-to-frequency converter.
The VFC emits pulses with separation proportional to the angular rotative and/or translational position of the moveable unit which pulses are applied to an LED of the moveable unit. A microcomputer in a base unit measures separation of the pulses received by a photodetector to determine the components of the angular rotative and/or translational position of the moveable unit. In accordance with another aspect, automatic gain control circuitry is located in the moveable unit, thereby eliminating the need for two-way communication to achieve consistency of operation in a prescribed space.

Description

`~o 93/u~o ~ t 3 6 ~ ~ ~ PCl'/VS93/~

~?OI~!ING DEVICE }Il~ NG :I:~PROVED 2~TO~ GAIN CO~:IROI~
~ PORMaTIO~ REPOR~
ESACKGROUND OF q~lE INVE?~lON
The present i~ven~ion rela~es to improvements 5 to a pointing device, suc~ as tha~ disclos~d in co~moxlly assigned U.S. Patent No. 5,045,843, the en~ir~ty o~ which is herei~ inccrporated by reference.
The invention which is the ~ubject of u.s.
Patent No. 5,045,843 sa~is:ies a need îor a system 10 facilitating remote control o~ a cursor on a display screen. Figure 1 illustrates an example OI a ba~;ic block diagram of the pointing device, shown at 40, acc:ording to the prior pz~tent. A ~irs~ unit 41, called a fixed unit or ba~;e w~it, is loca~ed proximat~ the lS display screen and in~erc:onnects 67ith a cursor control circui~ 13 associated with ~:he display screen 15, stls:h as a t~levision or a computer display screenO
The f i3c~d un~t 41 includes a driver 7 and a ~irst LED 9. A microc:ompu1:er ~ controls operat.ior~ of the 20 dri~er 7 as well ~s operation o~ the c:ursor control circuit 13 . The ieixed un it ~ur~er includes a photodetector 43 connected ~o ~:he microc~uter 5 via an analog-tc)-digital co~rerter 16 and a bu~iEer 45.
Th~ ~movab3e or remot~3 unit 4~ includ2s a cam~ra 25 19 having a lens 21, an elongia~ed ~ube ~3 and a pos~tion ~ensing de~ector 25 connec:~ed to opera~iorlal ampli~i~rs 29. The operation~l ampli~Eiers 29 a~pli~y the currents ~ l a ~
i~ 93/238~0 PCI~/U~93/04~05 - t received and translate them into proportic)nal v oltages.
The vc~ltages are digitized by ~he A/D converter 49 and process~d by t:he microcompu~er 51 to control operatiorl o~
the driver 5S which drives a second I ~D 57 .
In order to compensate for ambient light conditions, the sys~tem accordlng 'co the prior paterlt performs active dynamic gain con~rol in the fixed unit by two-way ("closed~ loop") communis~atiorl between the fixed unit and the mo~eable unit. Specifically, t:he int:ensity o~ ~he light ~rans~nitted by the ~ED of ~he ~ixed unit is controlled. This light intensiity is proportional to the ~;quare o~ the dis~ance }~etween the fixec~ unit and the moveable unit. ~he ~ixed unit and mov~able lanit .
communicate wi~:h each other in both directions to establish approprial:e illumina~ion le~els of the IR IED
9 in the fixed unit. ~rhe ampliîi~d output si~nals of ~e op~ratiorlal a~pli~Eiers are the~ digitized by the A~D
corlverter 49 to allow Sor p:roc:escing ~y the microco~nputer 51, 'rh~ step o~ dlg~tizi~g the ampli~i~d signal Por ultimate transmi sion is hereinafter re~erred tc) as "in~ormation reportirlg~lD
While the ~;ystem acc&rding to the prior patent adeguately pe!r~orms iits desired functiolls, there is roo~
~or improvement . Spec:if ieally, it is d~sirable to eli~ma~e the need ~or ~wo way, or c:lo~ed-loop, communication and to ac:complish aukomatic gain ce:3ntrol by ~'7 ~ t~

'--wb 03~0 2 1 3 6 1 9 1 PCT/US93/~0~ , adjusting the gain o~ the opexatio~al amplifiers in ~he moveable unit. It is also desirable ~o elimina~e the ~/D
co~version in the moveable unit.
S~ Y OF T~E INVEN~
Accordingly, ik is an o~ject o~ ~he pre~ent invention to provid~ for automatic gain control in an optical pointing device without ~he need for closed-loop communication be~ween ~he fixed unit and the moveahle unit thus achieving consistency o opera~ion throughout the prescribed space.
It is another o~ject of ~he present invention to provide a less computa~ionally in~en~iv~, and lower power, method a~d circuit arrangsment for reporting the angular rota~iv~ and/nr ~ra~slational position o~ a re~ote ~ontrol de~ice.
Brie~ly, in accordance-wi~h one aspect o~ th~
presen~ in~ention, ~hQ A/D con~rter in the ~oveable unit ~s replaced wi~h a voltage-~o-~requ~cy co~erter (VFC)o The VFC generates pulses with separa~ion proportional to input v~ltag~0 which pulses ar~ ap~lied to ~he ~ED o~ ~h~
~ov~ahle unit. This m~thod C~n5u~e5 much less power ~o transfflit ~he sa~e amount o~ da~a as ~ransmitking ~he digital ~alues ~rom the ~/D convert~rO T~e microcomputer in the ~ixed unit mea~ures the i~erYal bet~een pulses r~ceived by the photod~ector ~o det~rmine k~e relativ~

~ 2 :1 3 6 ~ 9 ~ p~,"s9~,~60~ -W093/23~0 strength of the voltages output by the operational amplifiers i~ the moveable unit.
In accordance with ano~her aspect o~ ~he present invention, au~omatic gain con~rol circuitry is located in the moveabl~ uni~, ~hereby elimînating the need for closed-loop co~munication to adjust the illumination intensi~y o~ the IR LED's in the fixed u~it as diskance between the ~ixed unik and moveable unit changes during use.
The above and o~her objec~s and advantages o~
~he present inven~ion will become more apparent when re~erence is made to the following description taken in con~unction with the accompanying drawing~O
E~IEF_DESCRIP~ ~
Figure 1 is a block diagram of the poi~ting syste~ according to the prior art described above.
Figure 2 is a block diagram o~ the pol~Sing sy~tem according ~o th~ present invention.
~ igure 3 is a timing dia~ram o~ the ~ignals generated in the moveable unit.
F~qure 4 is a timing diagram illustrating ~he t~chnigue of in~orma~ion reporting a~cording ~o ~he present invention.
Figure 5 is a block diagram of t~e state machine and associated logic circuitry i~ the mov~able unit.

yVO 93~238~0 ~ ~ 3 ~ ~ 9 ~ PCI/US93~0~605 D~3TATI,ED DESCRIPTION QF THE r)RAW~MGS `~
Referring to Figure 2, t~e block diagram o ths3 pointing syst~m according ~o the present in~ention i5 shown at 40~. The systera 40' is similar to system 40 of 5 'che prior paten~ (Figure 1) in some respects and like el~ments are referred to by like prir~ed refer~nce nulDbers .
As in the prior system the f ixed urlit 41 ' includes a driver 7~ and a first IED 9t. A microcQmputer 10 5 ' controls operation oS ~he driver 7 ' as well as op2ration of the cursor control circuit 13 ' ~f the display device 15~. ~ power supply 11' provides power to t.he micros~omputer 5'. The ~ixed u;nit 41' i~urth~r inc:ludes a photo~etector 43 ' connected to th~
5 microcom~uter 5 9 . (~he phc3todetec:tor 4 3 ' may be a type which outputs a digital signal, thu~; eli:2inating th~ need for the ~ circuit and bu~er shown in Figur~
The a~p~ck of the present invention d~aling with the moY~able lmit 100 ~ow will be describ~dO
20 Speci~ically, the m~veable unit 100 inc:ludes arl automatic gain control (A,~;C) cix~i~ 60, whereas in the prior design th~ fixed unit contained the active dynami c gain control circuitry. In addition, a voltage-to-~rç~uenc:y cornrer~er ~VFC) 61 i~ provided whic:h replaces an ar~aîog-25 to-digital con~rerter to produce the infor:natlon transmitted by the dri~rer an~ LED hardware in l;he ~093/23~0 ~ 3 6 ~ ~ ~ PCTIU~93/0~ 7 moveable unit 100. ~nd finally, a stat~ machine 62 is provided to control ~he opera~ion of t~e AGC circuit 6D
and the VFC 61, rather than a ~icrocomputer. The stat~
machi~e provides simple ~iming to manipulate control 5 lines to the AGC circuit 60 and the VCF 61. A
microcomputer is not required since no ac~ual computation is performed.
As in the prior syst~m, the moveable unit 100 includes a camera 19' ha~ing a len~ 21 t and a position 10 se~sing detector 25'. These ele~en~s are co~nectQd to both the AGC circuit 60 and ~o opera~ional ampli~iers 29'. The operational a~pli~iers are controlled by ~he AGC circui~ 60 and amplify the c~rr~nts g~nerated by ~he de~ector 25' in accordance wi~h ~he gain set by the AGC
15 circuit 60, and tra~slate these currents into pxoportional ~oltages a~ de~cribed with re~ren~e ko FigQr~s 1~21 of ~he prior pate~t~ Th~ operational ampli~iers 29' ~urn~sh these a~pli~ied signals to the VFC
61 whi~ gen~rates and s~nds pulses to the driv~x 55t to 20 actiVate a second 3ED 57'. The in~erval bQtwe2n ~hese pulse~ i5 proportional ~o the vol~age supplied by ~he operatio~al a~pli~iers 29'. ~he sta~e machine con~rols :
the AGC circuit 60 and the V~C 610 The moveable unit 100 is pre~erably powered by a battery 53' to allow for 2S porkabili~y.

., , ` '~ W~ 93/2384~ 3 ~ PC~r/US93/0~60s As das ::ribed abov~, there are three maj or improvements to the pointing device: (1) placing the automatic gain con~rol functionali~y in the motreablQ
unit; ( 2 ) using a state machine rather than a 5 mi:roco~puter; and ( 3 ) reporting ~e in~onnation det~c:ted by ~he position detector 25 by way o~ volta~e to-frequency conversion rather than analog-to-digital conversion.
By placing t~e At;C circuit 60 in the moveable 10 unit, c~rtain advantages are achieved over the prior sys~em. Wherea irl the prior sys~em, the ac:tive dynamic gain control circuit alter~3d the current applied to the LE~ 9 (Figure 1), automa~io gain co~rol is per~ormed completely in the ~noveable unit 100 ~us eliminating 15 c:losed-loop comm~rlication nece~sary in ~h~ prior ~ys~emO
The state machine 62 wh lich replaces the microcomputer 51 ~igure 1) re~uir~3s no ~emory and no cals::ula~iorl is p~rformed by t:h~ state machirle 62~, ~ 1 ~FC 61 e~llit5 p~llSÇ~5 wi~h separa~ion

2 0 propoEtion 1 to input voltz~ye . ~hese pulses are sent directly to ~:he IED 57 ' via ~e driv~r 55 ' . ~h~ result iE; that the data stream transmitted to the ~ixed unilt requires less illumination duration ~y the IED; there~ore th~ LED uses less battery Eaower . T~e microt:omputer 5 ' . 25 can measure the time interval be~ween ttQ~se puls~
received by the photodet~ctor 43 t 't O determix~e the ~ ~36~L9~
WO~3/23~0 PCT/~S93/~K05 relativ~ strengths of the vol~ages output by the operational ampli~iers ~9'. It is also possible to convert the voltages output by the operatio~al amplifiers 29' to ratios. The pulses sent by the VFC 61 are ratiometric in ~ha~ case. In any case, a voltage proportional to ~e ~otal gain applied also must be con~erted by the VFC 61 and reported to the fixed unit.
Referring now to Figures 3 and 4 in conjunction wi~h Figure 2, th~ nperation of ~e pointing system 40' will ~e described, first in gen~ral ~er~s, then in more detail. Firs~, in general ter~s, the microcomputer 5' controls ~he driver 7~ ~o cause ~he ~ir~t LED 9 ' to illumînate in a pred~termined manner. Thi~ ~ay be by way o~ signals of any predeter~ined leng~h, ~requency and pattern. ~ovement o~ the ~o~eabl unit 100 causes t~e bea~ o~ light from ~he f~rs~ $ED 9~ to be ~ocused os~ the surface of the positio~ sen~ing detec~or 25' ~n a ~ann2r corresponding to the angular rota~ive and/or tra~slat~o~al rela~ionship be~weeh the orientation of ~he l¢ns 21 and the ~ixed posi~ion of the ~irst LED g t .
Signals are gen~rated ~y ~e posit~on sensing detector 25' and are conveyed ~o ~he AGC circuit 60 which controls ~he gain o~ ~he operakional ~mpli~ers 29 once th~ gain has been determinad, ~he ~tat~ machine 62 causes the siqnals fro~ th~ posi~ion s~nsing de~ectsr ~5' to pa~s through the operat~onal ampli~iers 29' and to ~he ., /~ 9~J-23~40 ~ ~ 3 ~ L ~ 1 p~/Usg,3,04605 , . g VFC 61. The voltage~; ~enerated ~y the operatiorlal a~pliIiers 29' reprPsen~ing each of ~he components of the angular ro~a~ive arldjor ~ransla'cional relationship be~ween the ~ixed unit and the moveable unit and the 5 total gain applied ar~ hereina~ter colle~ti~ely ref erred to by the term "information signal". $he VFC: 61 puls~s t~e s2cond ~:D 5~ ' in a predetermined manner to report t~e in~ormation related to ~he proportioIIal voltages output by the position sensing detector 25 ' to the 10 photod~tec:tor 43' in ~he fixed unit ,l'. Such signals are convey~d via the mic:roc3m~uter ~' which r c~lves such ~;iynals, and in respoIlse, causes the appropriate operation oir ~he cursor coll'crol circ:uit :~3 t to ro.ove the cursor to a po~;itiorl on the screerl.
With r~erence to Figures 2-g, the oE)eration of the system 40' will be described in greatex del:ail. ~he :3tate mac:hiRe 62 controls operations in ~ mo~eable u~it lO0 and has ~wo modes: normal and powerdown, In th~
powerdown mode, ~he state machine in the mov~able ~anit 20 i90 has not rec:e~i~ed a signal ~rom the fixed unit 41' in a predetermilled amoun~ o~ ~i~e . I31 ~he poweædow~ mode ~
the sa~pling rate can be slowed or halted to save t~e battery li~Ee. To ob~ain tha normal processing mode, the select~r button 33 ' mus~ be depres~;ed okher~isa the slow 25 saDD.pl~ng rate will be in e~feck urltil a xemote illumislation pulse is receive~ ~:rom ~h~ f ixed unit .

3~40 ~ ~ 3 ~ 1 9 :i~ PCI'/US93/~5 ~ i _ Communication ~e~ween the ~ixed unit 41 ' and the remote unit 100 is ~ased on timing the intervals betwe2n front edges of in~rared pulses received by the fiaced unit 41~.
Communication may be initiated ~y ei'cher ~e 5 moveable unit lOO or the fixed unit 4~'. In the protc:ool where the moveable unit ini~ia~es, the mc)veable unit starl:s by issuing two he~der pulses 9P 100 mic:roseoonds duration and 1.1 mill~se~:onds separation~ The fixed unit ~1' uses the interval o~ lo 1 milliseconds to detect t~e 10 request. I~ the ~ixed unit ~ t de~ects the header, th~n 2 milliseconds after th2 firs~ pulse of l: he header, the f ixed unit 41 ' emits a 2 O 3cHz modula~ed in:Erared pulse for 9 . 2 millis~conds 1:o il~umi~a1:e ~h~ photodeteetor of the moveable unit lOO.
~eanwhile, in the moveable unit lOû, with 'cha state machine in the normal proc:essing mode, P~Rl a nd PWR2 signals are high for powering the operal;~nal ampli~ier~; 29' (~Ero~t end power) and the ~FC: 61 and ot~er associated circlaits ~rear end power~ O respecti~rely4 C3nc:e 20 an in:~rared pul~;e is recei~ed, the ~tate machine 62 activate~ ~he ~GC circui~ 60 to set ~he gain Or ~
op~ratiorlal ampli~iers 29' so that ~he voltages suppli~d to 'ch~ 61 are wi~hin a predetermin~d rang~
~ ;tate machin~ 62 c:sntrol~; the AGC circ~lit ~0 to ~3e~ ~he 25 galn Qi~ ~h~ op~ra~ic)nal ampli~iers 29'. This is donQ by ~ ~ 3 ~ pCr/U~93/0460 way of AGC, AS~;RST, GNG~ and ~;NCLR pulses and includes selection of one o~ two gain levels.
once the gain o~ tlle operational a~pli~i~rs is set by the AGC cirouit ~0, indlvidual d~tec:tor signals S (X~, X-, Y~, Y-) are gated seque~tially to the opDrational amplifiers 29 ' for generating a voltage.
These voltage~; are stored in capacitors for l::onversion by the VFC 61. Each of the sa~ples X+/ X-~ Y+, and Y- is as~;igned to distinct channels.
Al~ four vol~ages which are sampled are supplied to ~he VFC 61. A VERS~ pulse is generated by the state machine 62 be~ore eac~ of the voltzlges i5 output ~iequentially to the VFC 6~ ~OC0, OCl~ OC:2 and OC3) which in response generates pulses on the tl/F OUT pir 15 s~pzrated ~y time int:ersrals proport:ional to ~h~ ~agnitude o: th~ various voltage~;. In additiorl, ~ogether with the pulses representing ~he posi~:ion de~:ec,~or voltag~s, t~e gain set by t~e AGt: 60, c:alled G~I~, i5 aI50 ~on~ver1:ed by the VFC 61 to a time intenral between succ~ssive pul~es 20 on ~/F OUT, V/F 0~ is supplied to the driver 55' which rn dri~res the I,ED 57 ' to transmi t tlle inrared puls~s repres~ntative of 'V/F O~:IT.
Referring to Figure ~, the signals detec~ed by ~he positiorl de~ector 25' (and con~erted to pU15el5) 25 consists c~f five values: X~ , Y+, Y~ and GAIN. This data is transmil;ted by ~he L}~ 7'~ using the pulse ~3~91 ,iO 93/23840 Pcr/aJ593/Q~6o milliseconds ~rom the first of the header plllses. Th~
mov~able unit lOo will send a 100 microsecs3nd pulse at 14 . 2 milliseconds + (25 microseconds multipli~d by X*~ O
This is called the X+ pul se. The fixed unit 41g determines th~ value for X~ by measuring the differenc:e in tim2 between the f irs~ of the h~ader pulses and the rising edge of the X+ pulse subtracting 140 ~ milli~;econds and d.ividing by 25 ~icroseconds. The value X- is timed based on the X+ pulE;e plus ~he maximum setkle time o~ the photod~tector ~3 ~ which i5 1 ~mi3.1isecond~ X- i5 calculated as the X- pulse separa~ion from ~he X~ pulse less 1 millisecond divi~ed by 25 mic:roseconds. Y~, Y-and GAIN are similarly determined by the fixed lmit. To ensure that stray inrrared pulses dn not inter~Eere wi~h ~S ~he c:ommunication, a TAII, pulse i~ serlit by the moveabl~
u~it 100 1. 2 milli~3econds after khe last pi~ce og d (GAIN). ~rhe mov~ble unit 100 SQnd5 a total of d~ight 100 microsec:ond pul;es 1~ no switch pull~ aLre deteGted and the re~ote ill~irlation pulse is detected.
~rhese pulses are received by t~ p~otodetects~r 43 ' in the ~ixed un:it and supplied to the micro~;:t)mputer 5'. In th~ fix~d unit 41', the raw values X*, X-, Y~, Y-and GAIN are trans~ormed into X and Y coordinates. q~is i~ accomplished by the: mic:rocomputer 5 ' u~;ing a si~ple ratio of ~21e difrerence a~rer the Stl~ ~ultiplied by a constant. The constarit ~ repre~;ents a perf~srmance fac:tor rw093/23~ ~136191 Pcr/US~3/~

ratio o~ the difference over the sum multiplied by a constant. Th~ collstant L represents a per~ormance fa::tor oi~ the lens 219. For example, or an X c:t30rdinate spaee o~E G to 32,768, X = I.t (X~ - X-)/(X~ ~X-) I 16,384 +
5 16,384. The ~icrocomputer 5' is activat:ed to cc3ntrol the cursor control circuit 13 ' t~ move a cursor to a position aligned with the angular rotatiYe and/or translational position of the moveabl2 unitO
Figure 5 iE~ a schemati :: diagram of the state 10 machine, associated decoder and logic circuitry for generatir~g the variou c:on~rol signals ~or controlling the oE~erational amplifiers 2g ', P.GC circuit 60 and ~C:
61. The st2~te al~achine is driven by tk~e ST~T signal which is generated in response to receipt of the remote 15 illumirlatiosl pulse (I?igure 3~
Th~ tec:hnigue of reporting da~a related to the orientation og th~ ~oveable unit relative to the ~x~d unit i~S al~s~ use~ul in pointing devices in whi~

communication is ffl way o~ non-optic:al msza~ his 2 0 regard, the ~s~rQ~ e unit n~d only hav~ some ~ea~!; of determinlng ~he angular xo~ative and/c3r trz~n~;la~ional position o~ the mov~abl~ unit,.
The above description i~; intended by way o~
examplQ on:Ly and is not int~nded lt:G ~ it th~ pres~nt 25 inventi~n in any way ~xcept a~3 ~et ~or~h in th~ followi~g s:laims .

Claims

We claim:

1. An optical pointing device for use within a prescribed space for interconnection with a display device having a display screen, a cursor movable on said display screen and a cursor control circuit for controlling the position of the cursor on said display screen, the optical pointing device comprising:
a first unit including a light source and computer means for controlling the operation of said light source, said first unit being fixedly located relative to said display device with said computer means connected to said cursor control circuit;
a second unit movably contained within said space and comprising light detector means for detecting light emitted form aid light source to generate in response output signals related to the angular rotative and/or translational relationship between said light source and said light detector means, amplifying means connected to said light detector means for amplifying the output signals of said light detector means by an amplification factor to generate an information signal, automatic gain control means for changing the amplification factor of said amplifying means as distance between the first and second unit changes to adjust the level of the output signals of said light detector means which are amplified by said amplifying means and thereby to compensate for movement of the second unit relative to the first unit within said space.

2. The optical pointing device of claim 1, wherein said second unit further comprises transmission means for transmitting the information signal to the computing means of said first unit.

3. The optical pointing device of claim 2, wherein the transmission means of the second unit comprises optical transmission means for transmitting an optical signal, and the first unit further comprises light detection means connected to the computing means for receiving the optical signal transmitted by said optical transmission means.

4. The optical pointing device of claim 3, wherein said second unit further comprises means for controlling the automatic gain control means and the amplifying means.

5. The optical pointing device of claim 4, wherein the means for controlling comprises a state machine.

6. A pointing device for use within a prescribed space and adapted to be interconnected with a display device having a display screen, a cursor movable on said display screen and a cursor control circuit for controlling the position of the cursor on said display screen, the pointing device comprising:
a first unit including computer means connected to said cursor control circuit;
a second unit movably contained within said space and comprising orientation detection means for detecting angular rotative and/or translational and generating an information signal representative of a plurality of components of said angular rotative and/or translational signal to a series of spaced component pulses which are equal in number to the plurality of components, the time spacing between any two consecutive component pulses being proportional to a particular component of the angular rotative and/or translational position.

7. The device of claim 6, wherein the second unit comprises transmission means for transmitting the series of component pulses to the computer means of the first unit, and the computer means of the first unit converts the series of component pulses to cursor control data which is supplied to the cursor control circuit.

8. The device of claim 7, wherein the first unit comprises light detection means connected to said computer means, and the transmission means of the second unit comprises optical transmission means for transmit-ting the series of component pulses as a series of light pulses to the light detection means of said first unit.

9. The device of claim 6, wherein said first unit comprises a fixedly located light source and the orientation detection means of the second unit comprises light detector means for detecting light emitted from said light source and in response generating as output the information signal which represents components of the angular rotative and/or translational relationship between the light source and the light detector means.

10. A method for communicating the angular rotative and/or translational position of a moveable unit within a prescribed space to a receiving unit for inter-connection with a display device having a display screen, a cursor movable on said display screen an a cursor con-trol circuit for controlling the position of the cursor on said display screen, the method comprising the steps of:
detecting the angular rotative and/or translational position of the moveable unit;
generating an information signal which is indicative of a plurality of components of the angular rotative and/or translational position of the moveable unit;
converting the information signal into a series of spaced component pulses which are equal in number to the plurality of components, the time separation between any two consecutive component pulses being representative of a particular component of the angular rotative and/or translational position of the moveable unit; and transmitting the series of component pulses from the moveable unit to the receiving unit.

11. The method of claim 10, wherein the step of transmitting comprises the step of generating a series of light pulses which are transmitted to the receiving unit from the moveable unit.

12. The method of claim 10, and further comprising the steps of converting the series of component pulses received by the receiving unit to cursor control data and supplying the cursor control data to the cursor control circuit.

13. The method of claim 12, wherein the step of transmitting comprises the step of transmitting a series of light pulses to the receiving unit.

14. The method of claim 10, wherein said step of detecting the angular rotative and/or translational position of the moveable unit comprises detecting light emitted from a fixedly located light source at said receiving unit and in response generating as output the information signal which represents components of the angular rotative and/or translational position of the moveable unit.

15. A pointing device for use within a prescribed space for interconnection with a display device having a display screen, a cursor movable on said display screen and a cursor control circuit for controlling the position of the cursor on said display screen, the pointing device comprising:
a first unit including computer means connected to said cursor control circuit, said first unit being fixedly located relative to said display device;
and a second unit movably contained within said space and comprising orientation detection means for detecting angular rotative and/or translational position, amplifying means for amplifying the output signals of said orientation detection means by an amplification factor to generate an information signal, automatic gain control means for changing the amplification factor of said amplifying means as distance between the first and second unit changes to adjust the level of the output signals of said orientation detection means which are amplified by said amplifying means and thereby to allow for movement of the second unit relative to the first unit within said space.

16. A method for communicating the angular rotative and/or translational position of at least one moveable unit within a prescribed space to a receiving unit or to another moveable unit, the method comprising the steps of:
detecting the angular rotative and/or translational position of at least one moveable unit;

generating an information signal which is indicative of a plurality of components of the angular rotative and/or translational position of the at least one moveable unit;
converting the information signal into a series of spaced component pulses which are equal in number to the plurality of components, the time separation between any two consecutive component pulses being representative of a particular component of the angular rotative and/or translational position of the at least one moveable unit; and transmitting the series of pulses from the moveable unit to the receiving unit.

17. The method of claim 16, wherein the step of transmitting comprises the step of generating a series of light pulses which are transmitted from the moveable unit to the receiving unit or to another moveable unit.

18. An improvement to an optical pointing device for use within a prescribed space for interconnection with a display device having a display screen, a cursor movable on said display screen and a cursor control circuit for controlling the position of the cursor on the display screen, the optical pointing device comprising a first unit including computer means connected to said cursor control circuit and being fixedly located relative to said display device; and a second unit movably contained within said space and comprising orientation detection means for detecting angular rotative and/or translational position, amplifying means connected to said orientation detection means for amplifying the output signal of said orientation detection means by an amplification factor to generate an information signal, the improvement comprising:
automatic gain control means in said second unit for changing the amplification factor of said amplifying means as the distance between the first unit and second unit changes to adjust the level of the output signals of said orientation detection means and thereby to compensate for movement of the second unit relative to the first unit relative to the first unit within said space.

19. The improvement of claim 18, wherein said first unit includes a light source controlled by said computer means, and said orientation detection means of said second unit comprises light detector means for detecting light emitted from said light source to generate in response output signal related to the angular rotative and/or translational position between said light source and said light detector means.

20. An improvement to an optical pointing device for use within a prescribed space for interconnection with a display device having a display screen, a cursor movable on said display screen and a cursor control circuit for controlling the position of the cursor on the display screen, the optical pointing device comprising a first unit including computer means connected to said cursor control circuit and being fixedly located relative to said display device; and a second unit movably contained within said space and comprising orientation detection means for detecting angular rotative and/or translational position and to generate an information signal representative of a plurality of components of the angular rotative and/or translational position, the improvement comprising:
means for converting the information signal to a series of spaced component pulses which are equal in number to the plurality of components, the time spacing between any two consecutive component pulses being proportional to a particular component of the angular rotative and/or translational position.

21. The improvement of claim 20, wherein said first unit includes a light source controlled by said computer means, and said orientation detection means of said second unit comprises light detector means for detecting light emitted from said light source to generate as output the information signal which represents components of the angular rotative and/or translational position between said light source and said light detector means.

22. The improvement of claim 21, wherein the second unit further comprises optical transmission means for transmitting the series of component pulses to the computer means of the first unit, and the computer means of the first unit converts the series of component pulses to cursor control data which is supplied to the cursor control circuit.

23. The improvement of claim 21, wherein the means for converting receives as input, the information signal which comprises voltage signals representing spatial coordinates indicating the position on said light detector means of a light beam emitted by said light source of said first unit.

24. The pointing device of claim 6, wherein said means for converting receives as input the information signal in the form of a predetermined number of voltage signals each voltage signal representing one of said components, the series of pulses further comprising a lead pulse, and a tail pulse, the time spacing between a first component pulse and the lead pulse representing a first voltage signal, and the time spacing between succeeding consecutive pairs of said component pulses representing the remaining voltage signal.