초록 ▼

A method of predicting current boost levels and applying them to precharge current-driven elements in a matrix, and a method of manufacturing devices for this purpose. Elements are driven during successive scan cycles, each having a precharge period and an exposure period. One or more conduction vol

A method of predicting current boost levels and applying them to precharge current-driven elements in a matrix, and a method of manufacturing devices for this purpose. Elements are driven during successive scan cycles, each having a precharge period and an exposure period. One or more conduction voltages are sensed while an element conducts a selected current, either during a calibration cycle or during an exposure. A correct boost current is predicted from the conduction voltage(s) based upon other parameters including column capacitance, which may be determined upon manufacture, and the predicted boost current is then applied to matrix elements.

대표청구항 ▼

What is claimed is: 1. A method of adapting a quantity of electrical charge provided to a matrix element during precharge periods, the method comprising: driving a current through a matrix element connected to a matrix sense element; sensing a voltage of a path of the driven current to derive a ref

What is claimed is: 1. A method of adapting a quantity of electrical charge provided to a matrix element during precharge periods, the method comprising: driving a current through a matrix element connected to a matrix sense element; sensing a voltage of a path of the driven current to derive a reference voltage; predicting, based at least in part upon the reference voltage, a charge quantity that precharges the matrix element substantially to an equilibrium voltage value for a selected current; delivering the predicted charge quantity to the matrix element; providing a boost current to the matrix element during a precharge period, wherein said providing of boost current to the matrix element is omitted during said precharge period when said precharge period precedes an exposure period for which a conduction period of zero is assigned to the matrix element. 2. The method of claim 1, further comprising substantially determining a relationship between the reference voltage and an equilibrium value of the voltage of the path of the driven current. 3. The method of claim 2, further comprising determining that the reference voltage substantially equals the equilibrium value. 4. The method of claim 1, wherein sensing the path voltage further comprises charging a sample capacitor to the voltage in the path of the driven current. 5. The method of claim 4, further comprising temporarily coupling the sample capacitor to a hold capacitor. 6. The method of claim 5, further comprising temporarily coupling a plurality of sample capacitors to the hold capacitor. 7. The method of claim 1, further comprising digitizing the reference voltage with an analog/digital converter (ADC). 8. The method of claim 1, further comprising combining path voltages from a plurality of different matrix elements to establish the sense reference voltage. 9. The method of claim 1, further comprising averaging path voltages from a plurality of matrix elements over time to establish the reference voltage. 10. The method of claim 1, wherein the voltage is sensed during a scan cycle of normal operation. 11. The method of claim 1, wherein the voltage is sensed during a calibration exposure period that is distinct from normal operation. 12. The method of claim 1, wherein predicting the charge quantity comprises using a stored value representing an element capacitance. 13. The method of claim 12, further comprising determining a required charge voltage as a difference between the reference voltage and a voltage in the path of the driven current that is expected when the element is discharged. 14. The method of claim 13, further comprising predicting the charge quantity substantially based upon the required charge voltage multiplied by the matrix element capacitance value. 15. The method of claim 14, further comprising determining a desired precharge current from the predicted charge quantity divided by a precharge current delivery duration. 16. The method of claim 14, further comprising determining a desired precharge current duration from the predicted charge quantity divided by a precharge current level. 17. The method of claim 14, wherein the element capacitance value is stored permanently in association with a particular matrix device. 18. The method of claim 14, further comprising effectively determining an element capacitance value by determining a change in the sensed path voltage due to a charge delivered to the element. 19. The method of claim 1, further comprising adjusting a quantity of charge for precharge of particular matrix elements based upon expected conduction by other matrix elements. 20. The method of claim 1, further comprising periodically measuring an element voltage resulting from a precharge charge delivery. 21. The method of claim 20, further comprising adjusting the quantity of charge delivered during precharge in response to discrepancies between the measured element voltage resulting from a precharge charge delivery and an equilibrium value determined for the reference voltage at a present conduction current. 22. The method of claim 20, further comprising measuring the element voltage after an end of a precharge period. 23. The method of claim 1, further comprising discharging a particular matrix to a lower voltage during an exposure period at a termination of a conduction period for the particular matrix. 24. A method of adapting a quantity of electrical charge provided to a matrix element during precharge periods, the method comprising: driving a current through a matrix element connected to a matrix sense element; sensing a voltage of a path of the driven current to derive a reference voltage; predicting, based at least in part upon the reference voltage, a charge quantity that precharges the matrix element substantially to an equilibrium voltage value for a selected current; and delivering the predicted charge quantity to the matrix element; adjusting a quantity of charge for precharge of particular matrix elements based upon expected conduction by other matrix elements; and providing a boost current to a particular matrix element during a particular precharge period only when: (i) the particular matrix element has not conducted current during a conduction period subsequent to a preceding discharge, and (ii) a non-zero conduction is assigned for the particular matrix element during a conduction period immediately subsequent to the particular precharge period. 25. The method of claim 1, further comprising: deriving an estimate for a present exposure current value based upon a difference between the present current value and the sense current; and predicting a subsequent charge quantity for precharge based upon the estimate. 26. A method of adapting a quantity of electrical charge provided to a matrix element during precharge periods, the method comprising: driving a current through a matrix element connected to a matrix sense element; sensing a voltage of a path of the driven current to derive a reference voltage; predicting, based at least in part upon the reference voltage and a stored value representing an element capacitance, a charge quantity that precharges the matrix element substantially to an equilibrium voltage value for a selected current; delivering the predicted charge quantity to the matrix element; adjusting a quantity of charge for precharge of the matrix element based upon expected conduction by other matrix elements; determining a required charge voltage as a difference between the reference voltage and a voltage in the path of the driven current which is expected when the element is discharged; predicting the charge quantity substantially based upon the required charge voltage multiplied by the matrix element capacitance value; and effectively determining an element capacitance value by determining a change in the sensed path voltage due to a charge delivered to the element. 27. The method of claim 26, further comprising periodically measuring an element voltage resulting from a precharge charge delivery. 28. The method of claim 27, further comprising adjusting the quantity of charge delivered during precharge in response to discrepancies between the measured element voltage resulting from a precharge charge delivery and an equilibrium value determined for the reference voltage at a present conduction current. 29. The method of claim 26, further comprising providing a boost current to the matrix element during a precharge period, wherein said providing of boost current to the matrix element is omitted during said precharge period preceding an exposure period for which a conduction period of zero is assigned to the matrix element. 30. A method of adapting a quantity of electrical charge provided to a matrix element during precharge periods, the method comprising: driving a current through a matrix element connected to a matrix sense element; sensing a voltage of a path of the driven current to derive a reference voltage; predicting, based at least in part upon the reference voltage, a charge quantity that precharges the matrix element substantially to an equilibrium voltage value for a selected current; periodically measuring an element voltage resulting from a precharge charge delivery; delivering the predicted charge quantity to the matrix element; and adjusting the quantity of charge delivered during precharge in response to discrepancies between the measured element voltage resulting from a precharge charge delivery and an equilibrium value determined for the reference voltage at a present conduction current. 31. The method of claim 30, further comprising providing a boost current to the matrix element during a precharge period, wherein said providing of boost current to the matrix element is omitted during said precharge period preceding an exposure period for which a conduction period of zero is assigned to the matrix element. 32. A method of adapting a quantity of electrical charge provided to a matrix element during precharge periods, the method comprising: driving a current through a matrix element connected to a matrix sense element; sensing a voltage of a path of the driven current to derive a reference voltage; predicting, based at least in part upon the reference voltage and a stored value representing an element capacitance, a charge quantity that precharges the matrix element substantially to an equilibrium voltage value for a selected current; determining a required charge voltage as a difference between the reference voltage and a voltage in the path of the driven current that is expected when the element is discharged; delivering the predicted charge quantity to the matrix element; predicting the charge quantity substantially based upon the required charge voltage multiplied by the matrix element capacitance value; and determining a desired precharge current from the predicted charge quantity divided by a precharge current delivery duration. 33. The method of claim 32, further comprising periodically measuring an element connection voltage resulting from a precharge charge delivery. 34. The method of claim 33, further comprising adjusting the quantity of charge delivered during precharge in response to discrepancies between the measured element connection voltage resulting from a precharge charge delivery and an equilibrium value determined for the reference voltage at a present conduction current. 35. The method of claim 32, further comprising providing a boost current to the matrix element during a precharge period, wherein said providing of boost current to the matrix element is omitted during said precharge period preceding an exposure period for which a conduction period of zero is assigned to the matrix element. 36. A method of adapting a quantity of electrical charge provided to a matrix element during precharge periods, the method comprising: driving a current through a matrix element connected to a matrix sense element; sensing a voltage of a path of the driven current to derive a reference voltage; predicting, based at least in part upon the reference voltage and a stored value representing an element capacitance, a charge quantity that precharges the matrix element substantially to an equilibrium voltage value for a selected current; determining a required charge voltage as a difference between the reference voltage and a voltage in the path of the driven current that is expected when the element is discharged; delivering the predicted charge quantity to the matrix element; predicting the charge quantity substantially based upon the required charge voltage multiplied by the matrix element capacitance value; and determining a desired precharge current duration from the predicted charge quantity divided by a precharge current level. 37. The method of claim 36, further comprising periodically measuring an element voltage resulting from a precharge charge delivery. 38. The method of claim 37, further comprising adjusting the quantity of charge delivered during precharge in response to discrepancies between the measured element voltage resulting from a precharge charge delivery and an equilibrium value determined for the reference voltage at a present conduction current. 39. The method of claim 36, further comprising providing a boost current to the matrix element during a precharge period, wherein said providing of boost current to the matrix element is omitted during said precharge period preceding an exposure period for which a conduction period of zero is assigned to the matrix element.