Hand entry position sensing system

Claim 2

A position transducer system comprising: voltage gradient producing means producing a distributed voltage variation as a function of position in the direction of variation; voltage sensing means coupled by admittance to sense voltage at positions along said voltage gradient producing means; means causing said voltage sensing means to sense a first voltage from said voltage gradient producing means which is a composite function of both the position of said sensing means along said voltage gradient producing means and said admittance and a second voltage which is a function of said admittance; and means for determining the ratio to said first and second voltages to provide an output indication which is linearly related to the position of said voltage sensing means and is substantially independent of variation in coupling admittance.

Claim 3

The system as set forth in claim 1 wherein said admittance is capacitive.

Claim 4

In a position conversion system for reproducibly converting position into electrical signal indications including: voltage gradient producing means for producing a spatial voltage variation in at least one direction as a function of position in that direction; voltage sensing means coupled by admittance to said voltage gradient producing means; means for sampling and storing a first output voltage from said voltage sensing means which output voltage is a composite function of both the position of said voltage sensing means an said voltage gradient producing means and said admittance; means for sampling and storing a second output voltage from said voltage sensing means which output voltage is a function of admittance exclusive of position; and means for comparing said first and second stored voltages to provide a ratio thereof which is reproducibly related to positions on said voltage gradient means, independent of admittance.

Claim 5

In a position conversion system for reproducibly converting position into electrical signal indications including: voltage gradient producing means for producing a spatial voltage variation in at least one direction as a function of position in that direction; voltage sensing means coupled by admittance to said voltage gradient producing means; means for sampling and storing a first output voltage from said voltage sensing means which output voltage is a composite function of both the position of said voltage sensing means an said voltage gradient producing means and said admittance; means for sampling and storing a second output voltage from said voltage sensing means which output voltage is a function of admittance exclusive of position; and means for comparing said first and second stored voltages to provide a ratio thereof which is reproducibly related to positions on said voltage gradient means, independent of admittance.

Claim 6

In a handprint data entry transducer terminal system employing an electronic writing tablet and stylus wherein the stylus output voltage is an analog function of the position of the stylus on the tablet writing surface, including conversion means, said conversion means comprising: integration means coupled to said stylus including means for integrating said stylus output voltage over a set interval of time; means including timing means coupled to initiate integration of a reference voltage by said integration means at the beginning of a timing sequence in said timing means; output means coupled to said integration means including means to indicate the time, to, in said timing sequence at which the level of integration of said reference voltage reaches the level of integration reached by said stylus output voltage over said set interval of time.

Claim 7

In a handprint data entry transducer terminal system employing an electronic writing tablet and stylus wherein the stylus output voltage is an analog function of the position of the stylus on the tablet writing surface, including conversion means, said conversion means comprising: integration means coupled to said stylus including means for integrating said stylus output voltage over a set interval of time; means including timing means coupled to initiate integration of a reference voltage by said integration means at the beginning of a timing sequence in said timing means; output means coupled to said integration means including means to indicate the time, to, in said timing sequence at which the level of integration of said reference voltage reaches the level of integration reached by said stylus output voltage over said set interval of time.

Claim 8

The system as set forth in Claim 4 wherein said stylus output voltage over said set interval of time is a function of both the stylus position on said tablet writing surface and the coupling admittance between said stylus and the tablet voltage carrying surface, and said reference voltage is a function of said coupling admittance.

Claim 9

The system as set forth in Claim 5 wherein said system is under control of said timing means and said timing means includes a clock pulse source and a resettable counter with the time required for the clock pulses from said clock pulse sourcE to sequence all stages of said counter being greater than the time, t0.

Claim 10

The system as set forth in Claim 6 wherein said output means includes storage registers coupled to said counter and responsive to said means to indicated to load the count in said counter into said registers.

Claim 11

In the electronic position transducer system including: voltage producing means producing a distributed voltage variation in at least one direction which is a continuous function of distance in that direction; control means coupled to said voltage producing means including means to alternately switch said voltage producing means between a sample interval wherein said voltage variation is produced and a reference interval wherein a reference voltage is produced; voltage pickup means electrically coupled by admittance to a position along said voltage producing means to provide an output voltage, and output voltage, said output voltage being a composite function of both said position and said admittance during said sample interval and a function of said admittance during said reference interval; means for integrating said pickup means output voltage over sample intervals and holding the integrated voltage value at the end of said sample intervals; means for integrating said pickup means output voltage within reference intervals; and comparing means to determine when the value of voltage integrated during said reference intervals reaches said integrated voltage value at the end of said sample intervals.

Claim 12

In the electronic position transducer system including: voltage producing means producing a distributed voltage variation in at least one direction which is a continuous function of distance in that direction; control means coupled to said voltage producing means including means to alternately switch said voltage producing means between a sample interval wherein said voltage variation is produced and a reference interval wherein a reference voltage is produced; voltage pickup means electrically coupled by admittance to a position along said voltage producing means to provide an output voltage, and output voltage, said output voltage being a composite function of both said position and said admittance during said sample interval and a function of said admittance during said reference interval; means for integrating said pickup means output voltage over sample intervals and holding the integrated voltage value at the end of said sample intervals; means for integrating said pickup means output voltage within reference intervals; and comparing means to determine when the value of voltage integrated during said reference intervals reaches said integrated voltage value at the end of said sample intervals.

Claim 13

The system as set forth in Claim 8 wherein said means for integrating over said sample intervals and said means for integrating within said reference intervals respectively integrate on individual alternate sample and reference intervals.

Claim 14

In a conversion system for converting handprinted graphic data into electrical signals comprising: writing tablet means having voltage divider means including X-direction and a Y-direction impedance voltage divider means for providing distributed tablet voltage in the X and Y directions and including means for applying a periodic voltage signal alternately across said X-direction and said Y-direction impedance voltage divider means; stylus voltage pickup means coupled by admittance to said voltage divider means for sensing said tablet voltage as a function of stylus position on said tablet; control circuit means for alternately switching said voltage divider means between a first sample position wherein a first tablet voltage is produced the magnitude of which is a composite function of both said stylus position and said admittance and a second reference position wherein a second tablet voltage is produced the magnitude of which is a function of said admittance; detecting means coupled to said stylus for detecting the envelope of the periodic voltage produced by said tablet; circuit means coupled to said detecting means and including means for causing integration of the envelope of said first tablet voltage to provide a first integrated voltage level; said circuit means including further means for causing integration of the envelope of said second tablet voltage until it reaches said first integrated voltage level; and means coupled to said further means to indicate the period of time required for integration of said envelope of said second tablet voltage to the level of said first integrated voltage whereby said time is linearly related to the position of said stylus, independent of admittance.

Claim 15

In a conversion system for converting handprinted graphic data into electrical signals comprising: writing tablet means having voltage divider means including X-direction and a Y-direction impedance voltage divider means for providing distributed tablet voltage in the X and Y directions and including means for applying a periodic voltage signal alternately across said X-direction and said Y-direction impedance voltage divider means; stylus voltage pickup means coupled by admittance to said voltage divider means for sensing said tablet voltage as a function of stylus position on said tablet; control circuit means for alternately switching said voltage divider means between a first sample position wherein a first tablet voltage is produced the magnitude of which is a composite function of both said stylus position and said admittance and a second reference position wherein a second tablet voltage is produced the magnitude of which is a function of said admittance; detecting means coupled to said stylus for detecting the envelope of the periodic voltage produced by said tablet; circuit means coupled to said detecting means and including means for causing integration of the envelope of said first tablet voltage to provide a first integrated voltage level; said circuit means including further means for causing integration of the envelope of said second tablet voltage until it reaches said first integrated voltage level; and means coupled to said further means to indicate the period of time required for integration of said envelope of said second tablet voltage to the level of said first integrated voltage whereby said time is linearly related to the position of said stylus, independent of admittance.

Claim 16

The system as set forth in claim 10 with output means including digital means to digitally determine said period of time whereby the digitally determined time is indicative of the stylus position coordinates.

Claim 17

In a graphic information to digital data conversion system including a transducer system with electronic writing tablet means and stylus sensing means wherein the stylus output voltage is an analog function of the position of the sTylus on the writing tablet surface; sampling and integrating means coupled to said stylus for integrating said stylus output voltage over a set interval of time; circuit means including counting means and control circuit means to initiate integration of a reference voltage upon initiation of a count sequence in said counting means; comparing means responsive to said sampling and integrating means and to said circuit means for providing an output signal when the level of integration of said reference voltage reaches the level of integration of said voltage integrated within said set interval of time; register means responsive to the output signal of said comparing means for transferring the count on said counting means into said register means to thereby provide digital output coordinates indicative of stylus position.

Claim 18

In a graphic information to digital data conversion system including a transducer system with electronic writing tablet means and stylus sensing means wherein the stylus output voltage is an analog function of the position of the sTylus on the writing tablet surface; sampling and integrating means coupled to said stylus for integrating said stylus output voltage over a set interval of time; circuit means including counting means and control circuit means to initiate integration of a reference voltage upon initiation of a count sequence in said counting means; comparing means responsive to said sampling and integrating means and to said circuit means for providing an output signal when the level of integration of said reference voltage reaches the level of integration of said voltage integrated within said set interval of time; register means responsive to the output signal of said comparing means for transferring the count on said counting means into said register means to thereby provide digital output coordinates indicative of stylus position.

Claim 19

A graphic data entry terminal comprising: voltage gradient producing means for producing a spatial voltage variation in at least one direction as a function of position in that direction; stylus means coupled by admittance to said voltage gradient producing means to sense voltage from said voltage gradient producing means via said admittance coupling; circuit means coupled to said voltage gradient producing means and stylus means for causing integration over a first fixed time interval of a first voltage from said voltage gradient producing means which is a function of both the position of said stylus and said admittance and for causing integration over a second time interval of a second voltage from said voltage gradient producing means which is a function of said admittance exclusive of position; and means to terminate the integration over said second time interval when the level of integration of said second voltage reaches the level of integration of said first voltages, the time required to integrate said second voltage to the level of integration of said first voltage being reproducibly related to the position of said stylus, substantially independent of admittance.

Claim 20

A graphic data entry terminal comprising: voltage gradient producing means for producing a spatial voltage variation in at least one direction as a function of position in that direction; stylus means coupled by admittance to said voltage gradient producing means to sense voltage from said voltage gradient producing means via said admittance coupling; circuit means coupled to said voltage gradient producing means and stylus means for causing integration over a first fixed time interval of a first voltage from said voltage gradient producing means which is a function of both the position of said stylus and said admittance and for causing integration over a second time interval of a second voltage from said voltage gradient producing means which is a function of said admittance exclusive of position; and means to terminate the integration over said second time interval when the level of integration of said second voltage reaches the level of integration of said first voltages, the time required to integrate said second voltage to the level of integration of said first voltage being reproducibly related to the position of said stylus, substantially independent of admittance.

Claim 21

A position transducer arrangement comprising: distributive impedance means for producing a voltage gradient which gradient varies as a function of position along said impedance means; means coupled to said impedance means for energizing said impedance means to provide said voltage gradient across said impedance means over a fixed time interval and for energizing said impedance means to provide a uniform reference voltage across said impedance means over a variable time interval; voltage sensing means variably coupled by admittance to said distributive impedance means to sense voltage over said fixed time interval which is a function of both the position of said sensing means on said distributive impedance means and said admittance and to sense voltage over said variable time interval which is a function of said admittance; integrating means coupled to said sensing means to first integrate the voltage sensed over said fixed time interval and then integrate said reference voltage until the level of integration of said reference voltage equals the level of integration of said voltage integrated over said fixed time interval, the time interval required for the said level of integration of said reference voltage to build to the level of integration of said voltage integrated over said fixed time interval being said variable time and a function of the relative position of said sensing means on said distributive impedance means.

Claim 22

A position transducer arrangement comprising: distributive impedance means for producing a voltage gradient which gradient varies as a function of position along said impedance means; means coupled to said impedance means for energizing said impedance means to provide said voltage gradient across said impedance means over a fixed time interval and for energizing said impedance means to provide a uniform reference voltage across said impedance means over a variable time interval; voltage sensing means variably coupled by admittance to said distributive impedance means to sense voltage over said fixed time interval which is a function of both the position of said sensing means on said distributive impedance means and said admittance and to sense voltage over said variable time interval which is a function of said admittance; integrating means coupled to said sensing means to first integrate the voltage sensed over said fixed time interval and then integrate said reference voltage until the level of integration of said reference voltage equals the level of integration of said voltage integrated over said fixed time interval, the time interval required for the said level of integration of said reference voltage to build to the level of integration of said voltage integrated over said fixed time interval being said variable time and a function of the relative position of said sensing means on said distributive impedance means.

Claim 23

A position transducer arrangement comprising: an electronic writing tablet means including impedance means for alternately producing spatial voltage variations in the X-direction and the Y-direction as a function of position in those directions; means for energizing said writing tablet in said X-direction for a first fixed interval of time including means to energize said impedance means to provide said voltage variation in the x-direction across said impedance means as a functiOn of position for an initial fixed subinterval of said first interval of time and to provide a uniform reference voltage across said impedance means over a variable interval time, said variable interval of time being less than the difference in time between said first fixed interval of time and said subinterval of time, and means for energizing said writing tablet in said Y-direction for a second fixed interval of time including means to energize said impedance means to provide said voltage variation in the Y-direction across said impedance means as a function of position for an initial fixed subinterval of said second fixed interval of time and to provide a uniform reference voltage across said impedance means over a variable interval of time, said variable interval of time being less than the difference in time between said second fixed interval of time and said subinterval of time; voltage sensing means variably coupled by admittance to said writing tablet means to sense voltage from said writing tablet means, the voltage sensed during the subinterval of each of said first and second fixed interval of time being a composite function of both the position of sensing means on said writing tablet means in the respective said x- and y-directions and said admittance and the voltage sensed during the said variable interval of time of each of said first and second fixed interval of time being a function of admittance, exclusive of position; integrating means coupled to said sensing means to alternately integrate the voltage sensed during said first and second fixed intervals of time, said integrating means acting to first integrate the voltage sensed over said fixed subinterval of time and then to integrate said reference voltage until the level of integration of said reference voltage equals the level of integration of said voltage integrated over said fixed subinterval of time, the time interval required for the said level of integration of said reference voltage to build to the level of integration of said voltage integrated over said fixed subinterval of time being said variable interval of time and a function of the relative position of said sensing means on said writing tablet in the respective x and y-directions.

Claim 24

A position transducer arrangement comprising: an electronic writing tablet means including impedance means for alternately producing spatial voltage variations in the X-direction and the Y-direction as a function of position in those directions; means for energizing said writing tablet in said X-direction for a first fixed interval of time including means to energize said impedance means to provide said voltage variation in the x-direction across said impedance means as a functiOn of position for an initial fixed subinterval of said first interval of time and to provide a uniform reference voltage across said impedance means over a variable interval time, said variable interval of time being less than the difference in time between said first fixed interval of time and said subinterval of time, and means for energizing said writing tablet in said Y-direction for a second fixed interval of time including means to energize said impedance means to provide said voltage variation in the Y-direction across said impedance means as a function of position for an initial fixed subinterval of said second fixed interval of time and to provide a uniform reference voltage across said impedance means over a variable interval of time, said variable interval of time being less than the difference in time between said second fixed interval of time and said subinterval of time; voltage sensing means variably coupled by admittance to said writing tablet means to sense voltage from said writing tablet means, the voltage sensed during the subinterval of each of said first and second fixed interval of time being a composite function of both the position of sensing means on said writing tablet means in the respective said x- and y-directions and said admittance and the voltage sensed during the said variable interval of time of each of said first and second fixed interval of time being a function of admittance, exclusive of position; integrating means coupled to said sensing means to alternately integrate the voltage sensed during said first and second fixed intervals of time, said integrating means acting to first integrate the voltage sensed over said fixed subinterval of time and then to integrate said reference voltage until the level of integration of said reference voltage equals the level of integration of said voltage integrated over said fixed subinterval of time, the time interval required for the said level of integration of said reference voltage to build to the level of integration of said voltage integrated over said fixed subinterval of time being said variable interval of time and a function of the relative position of said sensing means on said writing tablet in the respective x and y-directions.