Method and system for writing data to MEMS display elements
First Claim
Patent Images
1. A method of actuating an electromechanical display element, the display element comprising a portion of an array of display elements, the method comprising:
- writing display data to the display element with a potential difference of a first polarity during a first portion of a display write process;
applying a first bias potential to the display element during a second portion of the display write process, the first bias potential causing a first potential difference across the display element with the first polarity; and
transitioning the potential applied to the display element from the first bias potential to apply a second bias potential polarity to the electromechanical display element during a third portion of the display write process, the second bias potential causing a second potential difference across the display element with a second polarity opposite the first polarity,wherein a transition time between applying the first bias potential and applying the second bias potential is configured such that the display element does not change states as a result of transitioning the voltage from the first bias potential to the second bias potential; and
wherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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Abstract
Charge balanced display data writing methods use write and hold cycles of opposite polarity during selected frame update periods. The transitions between voltages of opposite polarity are sufficiently brief that the display elements do not change state. A release cycle may be provided to reduce the chance that a given display element will become stuck in an actuated state.
435 Citations
33 Claims
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1. A method of actuating an electromechanical display element, the display element comprising a portion of an array of display elements, the method comprising:
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writing display data to the display element with a potential difference of a first polarity during a first portion of a display write process; applying a first bias potential to the display element during a second portion of the display write process, the first bias potential causing a first potential difference across the display element with the first polarity; and
transitioning the potential applied to the display element from the first bias potential to apply a second bias potential polarity to the electromechanical display element during a third portion of the display write process, the second bias potential causing a second potential difference across the display element with a second polarity opposite the first polarity,wherein a transition time between applying the first bias potential and applying the second bias potential is configured such that the display element does not change states as a result of transitioning the voltage from the first bias potential to the second bias potential; and wherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of actuating an electromechanical display element, the display element comprising a portion of an array of display elements, the method comprising:
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writing display data to the display element with a potential difference of a first polarity during a first portion of a display write process; applying a first bias potential having the first polarity to the display element during a second portion of the display write process; and transitioning the potential applied to the display element from the first bias potential to apply a second bias potential having a polarity opposite the first polarity to the electromechanical display element during a third portion of the display write process, wherein a transition time between applying the first bias potential and applying the second bias potential is configured such that the display element does not change states as a result of transitioning the voltage from the first bias potential to the second bias potential, wherein the transition time is less than or equal to τ
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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11. A method of maintaining a frame of display data on an array of electromechanical display elements, the method comprising alternately and sequentially transitioning a voltage applied to the electromechanical display elements between approximately equal bias potentials of opposite polarities so as to maintain a root mean square potential of the bias potentials within a hysteresis window of the electromechanical display elements wherein transitioning the voltage applied causes a potential difference across the display elements to vary between opposite polarities;
- and
wherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
- and
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12. A method of maintaining a frame of display data on an array of electromechanical display elements, the method comprising alternately and sequentially transitioning a voltage applied to the electromechanical display elements between approximately equal bias potentials of opposite polarities so as to maintain a root mean square potential of the bias potentials within a hysteresis window of the electromechanical display elements, wherein a transition time between the bias potentials is less than or equal to τ
-
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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iMoD+τ
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13. A method of writing frames of display data to an array of electromechanical display elements at a rate of one frame per defined frame update period, the method comprising:
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writing display data to the electromechanical display elements, wherein the writing takes less than the frame update period; and after the writing the display data, sequentially transitioning an applied voltage between bias potentials of alternating polarity to the electromechanical display elements for the remainder of the frame update period, wherein a root mean square potential of the applied voltage is within a hysteresis window of the electromechanical display elements, wherein transitioning the voltage applied causes a potential difference across the display elements to vary between opposite polarities; and wherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element. - View Dependent Claims (15)
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14. A method of writing frames of display data to an array of electromechanical display elements at a rate of one frame per defined frame update period, the method comprising:
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writing display data to the electromechanical display elements, wherein the writing takes less than the frame update period; and after the writing the display data, sequentially transitioning an applied voltage between bias potentials of alternating polarity to the electromechanical display elements for the remainder of the frame update period, wherein a root mean square potential of the applied voltage is within a hysteresis window of the electromechanical display elements, wherein a transition time between consecutive bias potentials is less than or equal to τ
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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16. An electromechanical display device, comprising:
- an array of electromechanical display elements; and
a driver configured to;
write display data to the display elements with a potential difference of a first polarity during a first portion of a display write process,apply a first bias potential to the display element during a second portion of the display write process, the first bias potential causing a first potential difference across the display element with the first polarity, and transition the potential applied to the display element from the first bias potential to apply a second bias potential to the electromechanical display element during a third portion of the display write process, the second bias potential causing a second potential difference across the display element with a second polarity opposite the first wherein a transition time between applying the first bias potential and applying the second bias potential is configured such that the display element does not change states as a result of transitioning the voltage from the first bias potential to the second bias potential; and wherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC com rises a constant related to electrical characteristics of the electromechanical display element. - View Dependent Claims (17, 18, 19, 20)
- an array of electromechanical display elements; and
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21. An electromechanical display device, comprising:
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an array of electromechanical display elements; and a driver configured to; write display data to the display elements with a potential difference of a first polarity during a first portion of a display write process, apply a first bias potential having the first polarity to the display element during a second portion of the display write process, and transition the potential applied to the display element from the first bias potential to apply a second bias potential having a polarity opposite the first polarity to the electromechanical display element during a third portion of the display write process, wherein a transition time between applying the first bias potential and applying the second bias potential is configured such that the display element does not change states as a result of transitioning the voltage from the first bias potential to the second bias potential, wherein the transition time is less than or equal to τ
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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22. An electromechanical display device, comprising:
- an array of electromechanical display elements; and
a driver configured to alternately and sequentially transition a voltage applied to the electromechanical display elements between approximately equal bias potentials of opposite polarities so as to maintain a root means square value of the bias potentials within a hysteresis window of the electromechanical display elements, wherein transitioning the voltage applied causes a potential difference across the display elements to vary between opposite polarities; andwherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
- an array of electromechanical display elements; and
-
23. An electromechanical display device, comprising:
-
an array of electromechanical display elements; and a driver configured to alternately and sequentially transition a voltage applied to the electromechanical display elements between approximately equal bias potentials of opposite polarities so as to maintain a root mean square value of the bias potentials within a hysteresis window of the electromechanical display elements, wherein a transition time between the bias potentials is less than or equal to τ
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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24. An electromechanical display device, comprising:
- an array of electromechanical display elements; and
a driver configured to;
write frames of display data to the array at a rate of one frame per defined frame update period, wherein the writing takes less than the frame update period, and after the writing the display data, sequentially transition an applied voltage between bias potentials of alternating polarity to the electromechanical display elements for the remainder of the frame update period, wherein a root mean square potential of the applied voltage is within a hysteresis window of the electromechanical display elements, wherein transitioning the voltage applied causes a potential difference across the display elements to vary between opposite polarities; andwherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element. - View Dependent Claims (26)
- an array of electromechanical display elements; and
-
25. An electromechanical display device, comprising:
-
an array of electromechanical display elements; and a driver configured to; write frames of display data to the array at a rate of one frame per defined frame update period, wherein the writing takes less than the frame update period, and after the writing the display data, sequentially transition an applied voltage between bias potentials of alternating polarity to the electromechanical display elements for the remainder of the frame update period, wherein a root mean square potential of the applied voltage is within a hysteresis window of the electromechanical display elements, wherein a transition time between consecutive bias potentials is less than or equal to τ
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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27. An electromechanical display device, comprising:
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means for writing display data to the display element with a potential difference of a first polarity during a first portion of a display write process; means for applying a first bias potential to the display element during a second portion of the display write process, the first bias potential causing a first potential difference across the display element with the first polarity; and means for transitioning the potential applied to the display element from the first bias potential to apply a second bias to the electromechanical display element during a third portion of the display write process, the second bias potential causing a second potential difference across the display element with a second polarity opposite the first polarity, wherein a transition time between applying the first bias potential and applying the second bias potential is configured such that the display element does not change states as a result of transitioning the voltage from the first bias potential to the second bias potential; and wherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element. - View Dependent Claims (28)
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29. An electromechanical display device, comprising:
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means for writing display data to the display element with a potential difference of a first polarity during a first portion of a display write process; means for applying a first bias potential having the first polarity to the display element during a second portion of the display write process; and means for transitioning the potential applied to the display element from the first bias potential to apply a second bias potential having a polarity opposite the first polarity to the electromechanical display element during a third portion of the display write process, wherein a transition time between applying the first bias potential and applying the second bias potential is configured such that the display element does not change states as a result of transitioning the voltage from the first bias potential to the second bias potential, wherein the transition time is less than or equal to τ
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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30. An electromechanical display device, comprising:
- an array of electromechanical display elements; and
means for alternately and sequentially transitioning a voltage applied to the electromechanical display elements between approximately equal bias potentials of opposite polarities so as to maintain a root mean square potential of the bias potentials within a hysteresis window of the electromechanical display elements, wherein transitioning the voltage applied causes a potential difference across the display elements to vary between opposite polarities; andwherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
- an array of electromechanical display elements; and
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31. An electromechanical display device, comprising:
-
an array of electromechanical display elements; and means for alternately and sequentially transitioning a voltage applied to the electromechanical display elements between approximately equal bias potentials of opposite polarities so as to maintain a root mean square potential of the bias potentials within a hysteresis window of the electromechanical display elements, wherein a transition time between the bias potentials is less than or equal to τ
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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32. An electromechanical display device, comprising:
- an array of electromechanical display elements; and
means for writing frames of display data to the array at a rate of one frame per defined frame update period, wherein the writing takes less than the frame update period, and means for sequentially transitioning an applied voltage between bias potentials of alternating polarity to the electromechanical display elements for the remainder of the frame update period, wherein a root mean square potential of the applied voltage is within a hysteresis window of the electromechanical display elements, wherein transitioning the voltage applied causes a potential difference across the display elements to vary between opposite polarities; andwherein a transition time between the bias potentials is less than or equal to “
τ
iMoD+“
τ
RC, wherein “
τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
- an array of electromechanical display elements; and
-
33. An electromechanical display device, comprising:
-
an array of electromechanical display elements; and means for writing frames of display data to the array at a rate of one frame per defined frame update period, wherein the writing takes less than the frame update period, and means for sequentially transitioning an applied voltage between bias potentials of alternating polarity to the electromechanical display elements for the remainder of the frame update period, wherein a root mean square potential of the applied voltage is within a hysteresis window of the electromechanical display elements, wherein a transition time between consecutive bias potentials is less than or equal to τ
iMoD+τ
RC, wherein τ
iMoD comprises a constant of the electromechanical display element determined with reference to physical characteristics of the electromechanical display element, and wherein τ
RC comprises a constant related to electrical characteristics of the electromechanical display element.
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Specification