Claims
- 1. A method for driving a column of display elements having a parasitic capacitance, the method comprising:
(a) during a pre-charge phase within a first row time period, pre-charging the column of display elements; (b) following the pre-charge phase, during a light emitting phase within the first row time period, applying a light emitting current to the column of display elements; (c) following the light emitting phase, during a partial-discharge phase within the first row time period, partially discharging the column of display elements; and (d) during an initial phase within a second row time period immediately following the first row time period, pre-charging the column of display elements if a light emitting phase is to be performed within the second row time period, otherwise further discharging the column of display elements if a light emitting phase is not to be performed within the second row time period.
- 2. The method of claim 1, wherein the initial phase within the second row time period immediately follows the partial-discharge phase within the first row time period.
- 3. The method of claim 1, wherein a tri-state phase occurs between the partial-discharge phase within the first row time period and the initial phase within the second row-time period, the tri-state phase being within the first row time period.
- 4. The method of claim 1, wherein:
step (a) includes applying a pre-charge current or a pre-charge voltage source to a node that is common to an anode of each display element in the column of display elements, to thereby produce a pre-charge voltage (Vpre) at the node; step (b) includes applying a light emitting current to the node, thereby producing a light emitting voltage (Vle) at the node; step (c) includes applying a partial-discharge current or a partial-discharge voltage source to the node, the thereby produce a partial-discharge voltage (Vpdis) at the node, the partial-discharge voltage (Vpdis) being less than the light emitting voltage (Vle); and step (d) includes:
applying the pre-charge current or the pre-charge voltage source to the node if a light emitting phase is to be performed within the second row time period, to thereby produce the pre-charge voltage (Vpre) at the node, the pre-charge voltage (Vpre) being greater than the partial discharge voltage (Vpdis); otherwise applying a discharge current or a discharge voltage source to the node if a light emitting phase is not to be performed within the second row time period, to thereby produce a discharge voltage (Vdis) at the node, the discharge voltage (Vdis) being less then the partial discharge voltage (Vpdis).
- 5. The method of claim 4, further comprising: between steps (c) and (d), during a tri-state phase within the first row time period, following the partial-discharge phase within the first row time period, applying no current from a column driver to the node.
- 6. The method of claim 4, wherein step (d) includes applying a discharge voltage source to the node if a light emitting phase is not to be performed within the second row time period, the discharge voltage being selected from a group consisting of:
ground; a voltage supply level slightly above ground; and a voltage supply level slightly below ground.
- 7. A method for driving a column of display elements having a parasitic capacitance, comprising:
(a) following a light emitting phase, where a display element in the column is selected to emit light, partially discharging the column; and (b) after the column is partially discharged, either further discharging the column or pre-charging the column, depending on whether a display element in the column is to be selected to emit light during a next row time period.
- 8. The method of claim 7, wherein step (b) includes:
(b.1) if a display element in the column is not to be selected to emit light during the next row time period, further discharging the column; otherwise (b.2) if a display element in the column is to be selected to emit light during the next row time period, pre-charging the column from a partial-discharge voltage (Vpdis) to a pre-charge voltage (Vpre), thereby preparing for a further light emitting phase during the next time period.
- 9. A method for driving a column of display elements having a parasitic capacitance, comprising:
(a) following a light emitting phase, where a display element in the column has been selected to emit light, partially discharging the column; and (b) after the column is partially discharged, further discharging the column during a next row time period if a display element in the column is not to be selected to emit light during the next row time period.
- 10. The method of claim 9, wherein step (b) includes, if a display element in the column is to be selected to emit light during the next row time period, applying a light emitting current to the column during the next row time period.
- 11. In a system including a column driver having an output connected to a column of display elements having a parasitic capacitance, a method for driving the column of display elements, comprising:
(a) following a light emitting phase within a row time period, where the column driver provided a light emitting current to the column, providing a partial-discharge current or a partial-discharge voltage from the column driver to the column during a partial-discharge phase within the row time period; (b) if the partial-discharge phase ends prior to an end of the row time period, applying no current from the column driver to the column during a tri-state phase that comprises a remainder of the row time period; and (c) after the row time period, either applying a discharge current or voltage, or a pre-charge current or voltage, from the column driver to the column, depending on whether the column driver is to provide the light emitting current to the column during a next row time period.
- 12. The method of claim 11, wherein step (c) includes:
(c.1) if the column driver is not to provide the light emitting current to the column during the next row time period, applying the discharge current or voltage; otherwise (c.2) if the column driver is to provide the light emitting current to the column during the next row time period, applying the pre-charge current or voltage.
- 13. A column driver adapted to drive a column of display elements having a parasitic capacitance, comprising:
a first switch adapted to provide a light emitting current to an output of the column driver, when the first switch is selected to be closed; a second switch adapted to provide a pre-charge current or voltage to the output of the column driver, when the second switch is selected to be closed; a third switch adapted to provide a partial-discharge current or voltage to the output of the column driver, when the third switch is selected to be closed; and a fourth switch adapted to selectively provide a discharge current or voltage to the output of the column driver, when the fourth switch is selected to be closed.
- 14. The column driver of claim 13, wherein the third switch and the fourth switch comprise a single switch that is coupled between a discharging current source and the output of the column driver, the partial-discharge current being provided to the output of the column driver when the single switch is closed for only a first time period, the discharge current being provided to the output of the column driver when the single switch is closed for at least a second time period.
- 15. The column driver of claim 13, wherein:
the first switch is coupled between a light emitting current source and the output of the column driver; the second switch is coupled between a pre-charge current or voltage source and the output of the column driver; the third switch is coupled between a partial-discharge current or voltage source and the output of the column driver; and the fourth switch is coupled between a discharge current source or discharge potential and the output of the column driver.
- 16. The column driver of claim 15, wherein the fourth switch is coupled between a discharge potential and the output of the column driver, and wherein the discharge potential is less than a voltage generated at the output of the column driver when the third switch is selected to provide the partial-discharge current or voltage source to the output of the column driver.
- 17. The column driver of claim 15, wherein the fourth switch is coupled between a discharge current source and the output of the column driver, and wherein a voltage produced at the output of the column driver when the fourth switch is selected to provide the discharge current source to the output of the column driver for a predetermined amount of time is less than a voltage generated at the output of the column driver when the third switch is selected to provide the partial-discharge current or voltage source to the output of the column driver.
- 18. The column driver of claim 13, wherein each switch is adapted to be selectively closed in response to a corresponding signal received by a finite state machine.
- 19. The column driver of claim 13, wherein the output of the column driver is adapted to be coupled to a node that is common to each display element in the column.
- 20. The column driver of claim 13, wherein each switch includes at least one transistor.
- 21. The column driver of claim 13, wherein each current source includes at least one transistor.
- 22. A column driver adapted to drive a column of display elements having a parasitic capacitance, comprising:
a first switch adapted to selectively provide a light emitting signal to an output of the column driver; a second switch adapted to selectively provide a partial-discharge signal to the output of the column driver; and a third switch adapted to selectively provide a discharge signal to the output of the column driver.
- 23. The column driver of claim 22, wherein:
the first switch is coupled between a light emitting current source and the output of the column driver; the second switch is coupled between a partial-discharge current or voltage source and the output of the column driver; and the third switch is coupled between a discharge current or potential and the output of the column driver.
- 24. The column driver of claim 23, wherein the third switch is coupled between a discharge potential and the output of the column driver, and wherein the discharge potential is less than a voltage generated at the output of the column driver when the second switch is selected to provide the partial-discharge current or voltage source to the output of the column driver.
- 25. The column driver of claim 23, wherein the third switch is coupled between a discharge current source and the output of the column driver, and wherein a voltage produced at the output of the column driver when the third switch is selected to provide the discharge current to the output of the column driver is less than a voltage generated at the output of the column driver when the second switch is selected to provide the partial-discharge current or voltage source to the output of the column driver.
- 26. The column driver of claim 22, wherein each switch is adapted to be selectively closed in response to a corresponding signal received by a finite state machine.
- 27. The column driver of claim 22, wherein the output of the column driver is adapted to be coupled to a node that is common to each display element in the column.
- 28. The column driver of claim 22, wherein each switch includes at least one transistor.
- 29. The column driver of claim 22, wherein current source includes at least one transistor.
- 30. A column driver adapted to drive a column of display elements having a parasitic capacitance, comprising:
a first switch coupled between a first current source and the column, the first switch adapted to provide a light emitting current to the column during a light emitting phase; a second switch coupled between a second current source and the column, the second switch adapted to cause a partial-discharge of the column during a partial discharge phase; and the second switch further adapted to cause a further discharge of the column during a discharge phase.
- 31. The column driver of claim 30, further comprising:
a third switch coupled between a third current source and the column, the third switch adapted to cause a pre-charge of the column during a pre-charge phase.
- 32. The column driver of claim 30, further comprising:
a third switch coupled between a voltage source and the column, the third switch adapted to cause a pre-charge of the column during a pre-charge phase.
- 33. A method for driving a row of display elements having a parasitic capacitance, the method comprising:
(a) during a pre-charge phase within a first column time period, pre-charging the row of display elements; (b) following the pre-charge phase, during a light emitting phase within the first column time period, applying a light emitting current to the row of display elements; (c) following the light emitting phase, during a partial-discharge phase within the first column time period, partially discharging the row of display elements; and (d) during an initial phase within a second column time period immediately following the first column time period, pre-charging the row of display elements if a light emitting phase is to be performed within the second column time period, otherwise further discharging the row of display elements if a light emitting phase is not to be performed within the second column time period.
PRIORITY CLAIM
[0001] This application claims priority to U.S. Provisional Patent Application No. 60/447,419, entitled “Methods and Systems for Driving OLED Displays,” which was filed on Feb. 14, 2003.
Provisional Applications (1)
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Number |
Date |
Country |
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60447419 |
Feb 2003 |
US |