US4054746A
Expired / Lapsed
US
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Electronic coordinate position digitizing system
Assignee: Data Automation Corp
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Filing: 1976-08-20
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Granted: 1977-10-18
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Expires: 1996-08-20
Abstract
Abstract An electronic position measuring system is disclosed for use in a digitizer of the type which converts analog information in graphical form to digital information. The system provides small scale or fine measurement by means of a polyphase grid winding with pulsed polyphase excitation. A cursor is movable over the grid winding and develops a position signal which has a phase angle corresponding to the position within a grid cycle. Phase angle measuring means are provided to derive the position information. The system also includes a large scale or coarse measurement grid comprising plural parallel conductors with at least one conductor per grid cycle. Excitation means are provided for sequentially pulsing the conductors and means connected with the cursor develop a stop signal in response to pulsing of the conductor nearest the cursor. A position counter counts the excitation pulses until the stop signal occurs and thus registers a count corresponding to the position of the cursor. The polyphase grid winding is provided with phase windings having plural distributed conductors per pole to produce an approximately sinusoidal distribution of magnetic flux over each pole of the winding to increase the accuracy of position measurement.
Inventors
- 👤 Vernon C. Kamm
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 00:16
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/046; G01; G01B; G01B7/00; G01B7/004; G01D; G01D5/00; G01D5/12; G01D5/14; G01D5/20; G01D5/204; G01D5/2073; G01D5/208; G01D5/244
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
131 words
Apparatus for measuring the position of a cursor along a coordinate axis on a reference surface comprising: a polyphase grid winding disposed in a plane parallel to said surface with each phase winding having multiple parallel conductors spaced in the direction of said coordinate axis and forming multiple pairs of poles in said grid winding, polyphase excitation means connected with said grid winding for sequentially applying square wave current pulses to the successive phase windings, said cursor including a sensing coil inductively coupled with the polyphase grid winding for producing a position signal having a phase angle corresponding to the position of the cursor within a pole pair of said grid winding, and means connected with the cursor and responsive to said position signal for determining the position of said cursor.
Claim 2
Dependent Claim
131 words
Apparatus for measuring the position of a cursor along a coordinate axis on a reference surface comprising: a polyphase grid winding disposed in a plane parallel to said surface with each phase winding having multiple parallel conductors spaced in the direction of said coordinate axis and forming multiple pairs of poles in said grid winding, polyphase excitation means connected with said grid winding for sequentially applying square wave current pulses to the successive phase windings, said cursor including a sensing coil inductively coupled with the polyphase grid winding for producing a position signal having a phase angle corresponding to the position of the cursor within a pole pair of said grid winding, and means connected with the cursor and responsive to said position signal for determining the position of said cursor.
Claim 3
Dependent Claim
19 words
The invention as defined in claim 1 wherein said pulses have a duration equal to the spacing between pulses.
Claim 4
Dependent Claim
50 words
The invention as defined in claim 1 wherein said last mentioned means comprises a clock pulse generator, a counter connected with said generator, and means for clearing said counter at the beginning of an excitation cycle, and means for stopping said counter when said position signal reaches a predetermined value.
Claim 5
Dependent Claim
35 words
The invention as defined in claim 3 wherein the means for stopping the counter includes an envelope detector connected with said cursor, and a zero crossing detector connected between said envelope detector and said counter.
Claim 6
Dependent Claim
29 words
The invention as defined in claim 1 wherein said polyphase excitation means comprises a set of current switches connected respectively with the phase windings of said polyphase grid winding.
Claim 7
Dependent Claim
43 words
The invention as defined in claim 1 including a coarse measuring means including counting means for counting the number of pole pairs of said grid winding between the origin of said coordinate axis and the poler pair within which the cursor is located.
Claim 8
Dependent Claim
117 words
The invention as defined in claim 6 wherein said counting means comprises a coarse measurement grid with plural parallel conductors disposed in a plane parallel to said surface and spaced in the direction of said coordinate axis with at least one conductor disposed within each pole pair of said polyphase grid winding, a coarse grid excitation means for sequentially applying said excitation pulses to said conductors of the coarse measurement grid, a position counter connected with said source of pulses, means for clearing said position counter at the beginning of the excitation cycle of the coarse measurement grid, stop pulse producing means connected with said cursor and responsive to a coarse excitation pulse for stopping said counter.
Claim 9
Dependent Claim
69 words
The invention as defined in claim 7 including control means connected with said polyphase excitation means and with said coarse grid excitation means for alternately enabling excitation of the polyphase grid winding and the coarse measurement grid whereby said cursor alternately produces a position signal in response to the excitation of the polyphase grid winding and a response pulse in response to the excitation of the coarse measurement grid.
Claim 10
Dependent Claim
36 words
The invention as defined in claim 1 wherein each phase winding includes plural conductors per pole with the conductors being distributed so that a current in the conductors produces an approximately sinusoidal distribution of magnetic flux.
Claim 11
Dependent Claim
27 words
The invention as defined in claim 9 wherein the sensing coil of said cursor is circular and has a diameter less than one-half of a pole length.
Claim 12
Dependent Claim
212 words
Apparatus for measuring the position of a cursor relative to a set of coordinate axes on a reference surface comprising an X-axis polyphase grid winding with each phase winding disposed in a plane parallel to said surface and having conductors spaced in the direction of the X-axis, a Y-axis polyphase grid winding with each phase winding disposed in a plane parallel to said surface and having conductors spaced in the direction of said Y-axis, X-axis switching means connected with said X-axis grid winding, Y-axis switching means connected with said Y-axis grid winding, a clock pulse generator, control means connected with said generator and having a first output and a second output connected respectively with said X-axis switching means and said Y-axis switching means, and producing X-axis and Y-axis enable pulses alternately on said first and second outputs, said cursor including a sensing coil inductively coupled with the X-axis and the Y-axis polyphase grid windings, said enable pulses alternately enabling said X-axis switching means and said Y-axis switching means whereby said X-axis and Y-axis grid windings are alternately excited and whereby said cursor alternately produces an X-axis position signal and a Y-axis position signal, and phase angle measuring means connected with the cursor for measuring the respective phase angles of the position signals.
Claim 13
Dependent Claim
212 words
Apparatus for measuring the position of a cursor relative to a set of coordinate axes on a reference surface comprising an X-axis polyphase grid winding with each phase winding disposed in a plane parallel to said surface and having conductors spaced in the direction of the X-axis, a Y-axis polyphase grid winding with each phase winding disposed in a plane parallel to said surface and having conductors spaced in the direction of said Y-axis, X-axis switching means connected with said X-axis grid winding, Y-axis switching means connected with said Y-axis grid winding, a clock pulse generator, control means connected with said generator and having a first output and a second output connected respectively with said X-axis switching means and said Y-axis switching means, and producing X-axis and Y-axis enable pulses alternately on said first and second outputs, said cursor including a sensing coil inductively coupled with the X-axis and the Y-axis polyphase grid windings, said enable pulses alternately enabling said X-axis switching means and said Y-axis switching means whereby said X-axis and Y-axis grid windings are alternately excited and whereby said cursor alternately produces an X-axis position signal and a Y-axis position signal, and phase angle measuring means connected with the cursor for measuring the respective phase angles of the position signals.
Claim 14
Dependent Claim
50 words
The invention as defined in claim 11 wherein said phase angle measuring means comprises a clock pulse generator, a counter connected with said generator, means for clearing said counter at the beginning of an excitation cycle, and means for stopping said counter when said position signal reaches a predetermined value.
Claim 15
Dependent Claim
143 words
Apparatus for measuring the position of a cursor along a coordinate axis on a reference surface comprising, a measurement grid including multiple parallel conductors spaced in the direction of the coordinate axis, grid excitation means connected with said conductors for sequentially applying current pulses thereto, a counter connected with said excitation means for counting the pulses, means for clearing the counter before the application of a pulse to the first conductor, said cursor including a sensing means coupled with the conductors for producing a cursor signal, stop pulse means connected with the sensing means for producing a stop pulse in response to a cursor signal caused by the excitation pulse applied to the conductor nearest the position of the cursor, said stop pulse means being connected with said counter to stop the counter at a count indicative of the position of the cursor.
Claim 16
Dependent Claim
143 words
Apparatus for measuring the position of a cursor along a coordinate axis on a reference surface comprising, a measurement grid including multiple parallel conductors spaced in the direction of the coordinate axis, grid excitation means connected with said conductors for sequentially applying current pulses thereto, a counter connected with said excitation means for counting the pulses, means for clearing the counter before the application of a pulse to the first conductor, said cursor including a sensing means coupled with the conductors for producing a cursor signal, stop pulse means connected with the sensing means for producing a stop pulse in response to a cursor signal caused by the excitation pulse applied to the conductor nearest the position of the cursor, said stop pulse means being connected with said counter to stop the counter at a count indicative of the position of the cursor.
Claim 17
Dependent Claim
19 words
The invention as defined in claim 13 wherein said sensing means comprises a coil inductively coupled with said conductors.
Claim 18
Dependent Claim
22 words
The invention as defined in claim 14 wherein said stop pulse means comprises a polarity sensitive amplifier having an adjustable threshold level.
Claim 19
Dependent Claim
122 words
The invention as defined in claim 14 including a polyphase grid winding disposed in a plane parallel to said surface with each phase winding having multiple parallel conductors spaced in the direction of said coordinate axis and forming multiple pairs of poles in said polyphase grid winding, at least one of the conductors of said measurement grid disposed within each pair of poles, polyphase excitation means connected with said polyphase grid winding, said cursor being inductively coupled with said polyphase grid winding for producing a position signal having a phase angle corresponding to the position of the cursor within a pair of poles of said grid winding, and means connected with the cursor for measuring the phase angle of said position signal.
Claim 20
Dependent Claim
68 words
The invention as defined in claim 16 including control means connected with said polyphase excitation means and with said grid excitation means for alternately enabling excitation of the polyphase grid winding and the coarse measurement grid whereby said cursor alternately produces a position signal in response to the excitation of the polyphase grid winding and a stop pulse in response to the excitation of the coarse measurement grid.
Claim 21
Dependent Claim
21 words
The invention as defined in claim 16 wherein two conductors of said measurement grid are disposed within each pair of poles.
Claim 22
Dependent Claim
21 words
The invention as defined in claim 18 including ambiguity resolving means connected with said position counter and said coarse excitation means.
Claim 23
Independent Claim
125 words
An apparatus for measuring the position of a cursor along a coordinate axis on a reference surface, said apparatus being of the type comprising a polyphase grid winding disposed in a plane parallel to said surface with each phase winding having multiple parallel conductors spaced in the direction of said axis and forming multiple pairs of poles in said grid winding, said cursor including a winding in coupled relation to said grid winding, excitation means connected with one of said windings, and phase angle measuring means connected with the others of said windings, the improvement comprising plural conductors per pole in each phase winding, the conductors of each pole being spaced apart within the pole length to produce an approximately sinusoidal distribution of magnetic flux.
Claim 24
Independent Claim
125 words
An apparatus for measuring the position of a cursor along a coordinate axis on a reference surface, said apparatus being of the type comprising a polyphase grid winding disposed in a plane parallel to said surface with each phase winding having multiple parallel conductors spaced in the direction of said axis and forming multiple pairs of poles in said grid winding, said cursor including a winding in coupled relation to said grid winding, excitation means connected with one of said windings, and phase angle measuring means connected with the others of said windings, the improvement comprising plural conductors per pole in each phase winding, the conductors of each pole being spaced apart within the pole length to produce an approximately sinusoidal distribution of magnetic flux.
Claim 25
Dependent Claim
21 words
The invention as defined in claim 20 including means to supply equal current to all of the conductors in each pole.
Claim 26
Dependent Claim
16 words
The invention as defined in claim 21 wherein all of the multiple conductors are equally spaced.
Claim 27
Dependent Claim
30 words
The invention as defined in claim 21 wherein said means to supply current is operative to supply current in the same direction through all the conductors in a given pole.
Claim 28
Dependent Claim
20 words
The invention as defined in claim 20 including means to supply unequal currents to the plural conductors in each pole.
Claim 29
Dependent Claim
49 words
The invention as defined in claim 20 including means for supplying current to the conductors in each pole with the value of current in a given conductor being proportional to the value at the position of the conductor of a sine wave distribution of flux over the pole length.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-17 | 1981-04-18 | 1981-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-17 | 1985-04-18 | 1985-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-17 | 1989-04-18 | 1989-10-18 | $7700.00 | Window Closed / Lapsed |