Methods for driving bistable electro-optic displays
AssigneeE Ink Corporation
InventorKarl R. Amundson
Life of this patent
Estimating the term…
Abstract
A bistable electro-optic display having at least one pixel is driven using a waveform V(t) such that: J = ∫ 0 T V ( t ) M ( T - t ) ⅆ t (where T is the length of the waveform, the integral is over the duration of the waveform, V(t) is the waveform voltage as a function of time t, and M(t) is a memory function that characterizes the reduction in efficacy of the remnant voltage to induce dwell-time-dependence arising from a short pulse at time zero) is less than about 1 volt sec.
Claims23
A method of driving a bistable electro-optic display having at least one pixel which comprises applying to the pixel a waveform V(t) such that:
- J
- =
- ∫
- 0
- T
-
- V
-
- (
- t
- )
-
- M
-
- (
- T
- -
- t
- )
-
- ⅆ
- t
- is less than about 1 volt sec,
- where:
- T is the length of the waveform, the integral is over the duration of the waveform, V(t) is the waveform voltage as a function of time t, and M(t) is a memory function that characterizes the reduction in efficacy of the remnant voltage to induce dwell-time-dependence arising from a short pulse at time zero, the waveform comprising a first pulse having a voltage, polarity and duration, and a second pulse having substantially the same voltage magnitude, a polarity opposite to that of the first pulse and a duration substantially less than that of the first pulse.
A method of driving a bistable electro-optic display having at least one pixel which comprises applying to the pixel a waveform V(t) such that:
- J
- =
- ∫
- 0
- T
-
- V
-
- (
- t
- )
-
- exp
-
- (
- -
- T
- -
- t
- τ
- )
-
- ⅆ
- t
- is less than about 1 volt sec,
- where:
- T is the length of the waveform, the integral is over the duration of the waveform, V(t) is the waveform voltage as a function of time t, and M(t) is a memory function that characterizes the reduction in efficacy of the remnant voltage to induce dwell-time-dependence arising from a short pulse at time zero, and τ is a predetermined decay time in the range of from about 0.2 to about 2 seconds.
A method of driving a bistable electro-optic display having at least one pixel which comprises applying to the pixel a waveform V(t) such that:
- J
- =
- ∫
- 0
- T
-
- V
-
- (
- t
- )
-
- M
-
- (
- T
- -
- t
- )
-
- ⅆ
- t
- is less than about 1 volt sec,
- where:
- T is the length of the waveform, the integral is over the duration of the waveform, V(t) is the waveform voltage as a function of time t, and M(t) is a memory function that characterizes the reduction in efficacy of the remnant voltage to induce dwell-time-dependence arising from a short pulse at time zero, wherein the waveform comprises two pairs of pulses, the pulses of each pair having substantially the same voltage magnitude and being of equal duration but opposite in polarity, and the pulses of the second pair having a duration longer than the pulses of the first pair, the two pulse pairs being applied in either of the following orders:
- (a) the first pulse of the first pair;
- the first pulse of the second pair;
- the second pulse of the second pair;
- and the second pulse of the first pair;
- or
- (b) the first pulse of the first pair;
- the second pulse of the first pair. the first pulse of the second pair;
- and the second pulse of the second pair.
A method of driving a bistable electro-optic display having at least one pixel which comprises applying to the pixel a waveform V(t) such that:
- J
- =
- ∫
- 0
- T
-
- V
-
- (
- t
- )
-
- M
-
- (
- T
- -
- t
- )
-
- ⅆ
- t
- is less than about 1 volt sec,
- where:
- T is the length of the waveform, the integral is over the duration of the waveform, V(t) is the waveform voltage as a function of time t, and M(t) is a memory function that characterizes the reduction in efficacy of the remnant voltage to induce dwell-time-dependence arising from a short pulse at time zero, M(t) is a sum of multiple exponential functions, as follows:
- M
-
- (
- t
- )
- =
- ∑
- k
- =
- 1
- N
-
- a
- k
-
- exp
-
- (
- -
- t
- /
- τ
- k
- )
- where each term in the sum of N exponential terms has amplitude αk and decay time τk.
A method of driving a bistable electro-optic display having at least one pixel which comprises applying to the pixel a waveform V(t) such that:
- J
- d
- =
- ∫
- 0
- T
- +
- Δ
-
- V
-
- (
- t
- )
-
- M
-
- (
- T
- +
- Δ
- -
- t
- )
-
- ⅆ
- t
- is less than about 1 volt sec,
- where T is the length of the waveform, the integral is over the duration of the waveform, V(t) is the waveform voltage as a function of time t, M(t) is a memory function that characterizes the reduction in efficacy of the remnant voltage to induce dwell-time-dependence arising from a short pulse at time zero, and Δ is a positive period less than the period T.
A method of driving a bistable electro-optic display having at least one pixel capable of displaying at least three different optical states, which method comprises applying to the pixel a set of waveforms V(t) sufficient to cause the pixel to undergo all possible transitions among its various optical states, the waveforms of the set all being such that:
- J
- d
- =
- ∫
- 0
- T
- +
- Δ
-
- V
-
- (
- t
- )
-
- M
-
- (
- T
- +
- Δ
- -
- t
- )
-
- ⅆ
- t
- is less than about 40 per cent of the transition impulse,
- where T is the length of the waveform, the integral is over the duration of the waveform, V(t) is the waveform voltage as a function of time t, M(t) is a memory function that characterizes the reduction in efficacy of the remnant voltage to induce dwell-time-dependence arising from a short pulse at time zero, and Δ is a positive period less than the period T, or 0.
Dependencies are inferred from the claim text.