Patent US4213005A successfully refreshed from Google Patents.
US4213005A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digitizer tablet
Assignee: Individual
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Filing: 1978-12-13
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Granted: 1980-07-15
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Expires: 1998-12-13
Abstract
Abstract A system for precisely determining the location of a cursor on a work surface with respect to a grid of coordinate conductors. The system is based on the time-distance relationship of current sheets caused to move sequentially along each axis of the work surface, and the detection of each current sheet as it approaches and passes an operator-movable sensor. A number of the grid wires are simultaneously energized with a fixed energization pattern which steps along the conductors, thereby generating the current sheet and consequent magnetic field which translate along the plane of the conductors parallel to the conductors. A preferred means responsive to the time of passage of the current sheet comprises an inductive pickup coil having a diameter approximately equal to the width of the current sheet and means for sensing current induced in the pickup coil. Preferably, the grid conductors are energized with substantially fixed constant currents. Among the important advantages of the invention are enhanced signal levels with improved signal to noise ratios, improved immunity to extraneous noise, relative insensitivity to minor inaccuracies in the placement of the grid wires in the manufacture of the tablet, excellent resolution, and a high degree of stability. Moreover, the system, through several discoveries, is characterized by a relative lack of undue complexity, while serving well its intended function.
Inventors
- 👤 Eugene A. Cameron
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:36
CPC Classifications
G; G06; G06F; G06F3/00; G06F3/01; G06F3/03; G06F3/041; G06F3/046
Claims Analysis
Total Claims: 36
Claim 1
Independent Claim
120 words
A system for locating the position of a cursor along a coordinate axis, said system comprising: a plurality of parallel conductors spaced along the axis and defining a locus; means for sequentially energizing said conductors in simultaneously energized lesser pluralities with a fixed energization pattern which steps along said plurality of conductors, thereby generating a current sheet which translates along the locus of and parallel to said conductors; means for sensing the passage of a particular portion of the current sheet across a reference point carried by the cursor; and means responsive to the time of passage of the particular portion of the current sheet for generating an output signal representing the position of the cursor along the coordinate axis.
Claim 2
Independent Claim
120 words
A system for locating the position of a cursor along a coordinate axis, said system comprising: a plurality of parallel conductors spaced along the axis and defining a locus; means for sequentially energizing said conductors in simultaneously energized lesser pluralities with a fixed energization pattern which steps along said plurality of conductors, thereby generating a current sheet which translates along the locus of and parallel to said conductors; means for sensing the passage of a particular portion of the current sheet across a reference point carried by the cursor; and means responsive to the time of passage of the particular portion of the current sheet for generating an output signal representing the position of the cursor along the coordinate axis.
Claim 3
Dependent Claim
23 words
A system according to claim 1, wherein said conductors are uniformly spaced and wherein the energization pattern steps along at a uniform rate.
Claim 4
Dependent Claim
17 words
A system according to claim 2, which further comprises means for energizing said conductors with constant currents.
Claim 5
Dependent Claim
21 words
A system according to claim 1, wherein the fixed energization pattern comprises all of said lesser plurality of conductors being energized.
Claim 6
Dependent Claim
17 words
A system according to claim 4, which further comprises means for energizing said conductors with constant currents.
Claim 7
Dependent Claim
13 words
A system according to claim 4, wherein said lesser plurality comprises seven conductors.
Claim 8
Dependent Claim
14 words
A system according to claim 1, wherein said cursor carries an inductive pickup coil.
Claim 9
Dependent Claim
29 words
A system according to claim 7, wherein the diameter of said inductive pickup coil is approximately equal to the width of the current sheet along its direction of translation.
Claim 10
Dependent Claim
32 words
A system according to claim 8, wherein said means for sensing the passage of a particular portion of the current sheet includes means for sensing current induced in said inductive pickup coil.
Claim 11
Dependent Claim
32 words
A system according to claim 7, wherein said means for sensing the passage of a particular portion of the current sheet includes means for sensing current induced in said inductive pickup coil.
Claim 12
Dependent Claim
17 words
A system according to claim 10, which further comprises means for energizing said conductors with constant currents.
Claim 13
Dependent Claim
15 words
A system according to claim 10, wherein said current sensing means comprises a current-to-voltage converter.
Claim 14
Dependent Claim
41 words
A system according to claim 10, wherein said means for sensing the passage of a particular portion of the current sheet comprises a low pass frequency filter for generating a waveform envelope representative of current induced in said inductive pickup coil.
Claim 15
Dependent Claim
64 words
A system according to claim 13, wherein said means for sensing the passage of a particular portion of the current sheet further comprises: a first comparator responsive to the waveform envelope crossing a threshold; a second comparator responsive to the waveform envelope crossing another threshold for generating a timing signal; and means for enabling said second comparator only in response to said first comparator.
Claim 16
Dependent Claim
60 words
A system according to claim 14, wherein said second comparator is enabled for a predetermined interval selected to allow response to the waveform crossing the other threshold when the portion of the current sheet actually crosses the reference point and selected to minimize the possibility of response to the waveform crossing the other threshold due to an extraneous noise signal.
Claim 17
Dependent Claim
17 words
A system according to claim 1, which further comprises means for energizing said conductors with constant currents.
Claim 18
Dependent Claim
17 words
A system according to claim 1, wherein said conductors comprise insulated wires bonded to a ferromagnetic substrate.
Claim 19
Dependent Claim
16 words
A system according to claim 1, wherein said conductors comprise wires bonded to a glass substrate.
Claim 20
Dependent Claim
64 words
A system according to claim 1, wherein said means for sequentially energizing said conductors in simultaneously energized lesser pluralities comprises: a serial-in/parrallel-out shift register having outputs connected to energize corresponding ones of said conductors; means for clocking said serial-in/parallel-out shift register; and means synchronized with said clocking means for serially entering data into said serial-in/parallel-out shift register in accordance with the fixed energization pattern.
Claim 21
Dependent Claim
56 words
A system according to claim 19, wherein said means for serially entering data comprises a parallel-in/serial-out shift register having its parallel data inputs connected to fixed logic levels in accordance with the fixed energization pattern and having its serial input connected to a fixed logic level appropriate to establish the trailing edge of the current sheet.
Claim 22
Independent Claim
208 words
A system for locating the position of a cursor on a surface, said system comprising: a conductor grid including a first plurality of parallel conductors spaced along a first axis in a plane parallel to the surface, and including a second plurality of parallel conductors spaced along a second axis perpendicular to said first axis, also in a plane parallel to the surface, such that the conductors of said second plurality are perpendicular to the conductors of said first plurality; means for sequentially energizing the conductors in simultaneously energized lesser pluralities with a fixed energization pattern which steps first along said first plurality of conductors and then along said second plurality of conductors, thereby generating a first current sheet which translates along the plane of and parallel to the conductors of the first plurality followed by a second current sheet which translates along the plane of and parallel to the conductors of the second plurality; means for sensing the passage of a particular portion of each of the current sheets across a reference point carried by the cursor; means responsive to the times of passage of the particular portions of the current sheets for generating an output signal representing the coordinate position of the cursor on the surface.
Claim 23
Independent Claim
208 words
A system for locating the position of a cursor on a surface, said system comprising: a conductor grid including a first plurality of parallel conductors spaced along a first axis in a plane parallel to the surface, and including a second plurality of parallel conductors spaced along a second axis perpendicular to said first axis, also in a plane parallel to the surface, such that the conductors of said second plurality are perpendicular to the conductors of said first plurality; means for sequentially energizing the conductors in simultaneously energized lesser pluralities with a fixed energization pattern which steps first along said first plurality of conductors and then along said second plurality of conductors, thereby generating a first current sheet which translates along the plane of and parallel to the conductors of the first plurality followed by a second current sheet which translates along the plane of and parallel to the conductors of the second plurality; means for sensing the passage of a particular portion of each of the current sheets across a reference point carried by the cursor; means responsive to the times of passage of the particular portions of the current sheets for generating an output signal representing the coordinate position of the cursor on the surface.
Claim 24
Dependent Claim
17 words
A system according to claim 21, which further comprises means for energizing said conductors with constant currents.
Claim 25
Dependent Claim
14 words
A system according to claim 21, wherein said cursor carries an inductive pickup coil.
Claim 26
Dependent Claim
32 words
A system according to claim 23, wherein said means for sensing the passage of the particular portions of the current sheets includes means for sensing current induced in said inductive pickup coil.
Claim 27
Dependent Claim
17 words
A system according to claim 24, wherein said current sensing means comprises a current to voltage converter.
Claim 28
Dependent Claim
25 words
A system according to claim 23, wherein the diameter of said inductive pickup coil is approximately equal to the widths of the generated current sheets.
Claim 29
Dependent Claim
32 words
A system according to claim 26, wherein said means for sensing the passage of the particular portions of the current sheets includes means for sensing current induced in said inductive pickup coil.
Claim 30
Dependent Claim
17 words
A system according to claim 26, which further comprises means for energizing said conductors with constant currents.
Claim 31
Dependent Claim
97 words
A sensing arrangement for use in a system for locating the position of a cursor along a coordinate axis of the type which sequentially energizes a plurality of parallel conductors spaced along the axis to produce a current wave which translates along the axis, and which responds to the time of passage of the current wave across the cursor to generate an output signal representing the position of the cursor along the coordinate axis, said sensing arrangement comprising: an inductive pickup coil carried by the cursor; and means for sensing current induced in said inductive pickup coil.
Claim 32
Dependent Claim
97 words
A sensing arrangement for use in a system for locating the position of a cursor along a coordinate axis of the type which sequentially energizes a plurality of parallel conductors spaced along the axis to produce a current wave which translates along the axis, and which responds to the time of passage of the current wave across the cursor to generate an output signal representing the position of the cursor along the coordinate axis, said sensing arrangement comprising: an inductive pickup coil carried by the cursor; and means for sensing current induced in said inductive pickup coil.
Claim 33
Dependent Claim
15 words
A system according to claim 29, wherein said current sensing means comprises a current-to-voltage converter.
Claim 34
Dependent Claim
169 words
In a system for locating the position of a cursor along a coordinate axis of the general type which sequentially energizes a plurality of parallel conductors spaced along the axis to produce a current wave which translates along the axis, and which includes means responsive to the time of passage of the current wave across the cursor to generate an output signal representing the position of the cursor along the coordinate axis, means for sensing the time of passage of a particular portion of the current sheet across a reference point carried by the cursor, which means for sensing comprises: an inductive pickup coil carried by the cursor; means responsive to a signal induced in said pickup coil as the current wave passes for generating a waveform envelope; a first comparator responsive to the waveform envelope crossing a threshold; a second comparator responsive to the waveform envelope crossing another threshold for generating a timing signal; and means for enabling said second comparator only in response to said first comparator.
Claim 35
Dependent Claim
169 words
In a system for locating the position of a cursor along a coordinate axis of the general type which sequentially energizes a plurality of parallel conductors spaced along the axis to produce a current wave which translates along the axis, and which includes means responsive to the time of passage of the current wave across the cursor to generate an output signal representing the position of the cursor along the coordinate axis, means for sensing the time of passage of a particular portion of the current sheet across a reference point carried by the cursor, which means for sensing comprises: an inductive pickup coil carried by the cursor; means responsive to a signal induced in said pickup coil as the current wave passes for generating a waveform envelope; a first comparator responsive to the waveform envelope crossing a threshold; a second comparator responsive to the waveform envelope crossing another threshold for generating a timing signal; and means for enabling said second comparator only in response to said first comparator.
Claim 36
Dependent Claim
60 words
A system according to claim 31, wherein said second comparator is enabled for a predetermined interval selected to allow response to the waveform crossing the other threshold when the portion of the current sheet actually crosses the reference point and selected to minimize the possibility of response to the waveform crossing the other threshold due to an extraneous noise signal.
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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) | 1983-07-15 | 1984-01-14 | 1984-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-07-15 | 1988-01-14 | 1988-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-07-15 | 1992-01-14 | 1992-07-15 | $7700.00 | Window Closed / Lapsed |