Multistable cholesteric liquid crystal devices driven by width-dependent voltage pulse

Claim 2

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage, and wherein the driving voltage is a function of the width of a voltage pulse.

Claim 3

The liquid crystal device of claim 1, wherein the first conductive layer is coated with a first amorphous boundary layer.

Claim 4

The liquid crystal device of claim 2, wherein the first amorphous boundary layer comprises a polyimide.

Claim 5

The liquid crystal device of claim 2, wherein the first amorphous boundary layer comprises a silane.

Claim 6

The liquid crystal device of claim 2, wherein the first amorphous boundary layer is in a random relationship with the liquid crystals in a planar direction.

Claim 7

The liquid crystal device of claim 1, wherein the second conductive layer is coated with a second amorphous boundary layer.

Claim 8

The liquid crystal device of claim 6, wherein the second amorphous boundary layer comprises a polyimide.

Claim 9

The liquid crystal device of claim 6, wherein the second amorphous boundary layer comprises a silane.

Claim 10

The liquid crystal device of claim 6, wherein the second amorphous boundary layer is in a random relationship with the liquid crystals in a planar direction.

Claim 11

The liquid crystal device of claim 1, wherein the liquid crystal mix is substantially free of polymer additive.

Claim 12

The liquid crystal device of claim 1, wherein removing the driving voltage across the liquid crystal material whereby the domain orientation is transformed from one state to a different state.

Claim 13

The liquid crystal device of claim 1, wherein the driving voltage is a single voltage pulse.

Claim 14

The liquid crystal device of claim 12, wherein the speed of changing the domain orientation of the liquid crystal material is dependent on both the height of the driving voltage and the width of the voltage pulse.

Claim 15

The liquid crystal device of claim 12, wherein the single voltage pulse allows achievement of an unlimited gray scale capability.

Claim 16

The liquid crystal device of claim 1, wherein the driving voltage is applied by means of a matrix drive method wherein: V.sub.N =(V.sub.R -V.sub.S)/2; and wherein V N is the minimum cross-talk voltage, V R is the voltage pulse required to achieve the maximum zero field stable reflective state, and V S is the driving voltage having a value intermediate between V T and V C , and close to V C , wherein V T is the threshold voltage and V C is the critical voltage required to induce a phase change from cholesteric to nematic.

Claim 17

The liquid crystal device of claim 15, wherein V N is smaller than V T , and wherein V T is the threshold voltage.

Claim 18

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage comprising a succession of pulses.

Claim 19

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage comprising a succession of pulses.

Claim 20

The liquid crystal device of claim 17, wherein the succession of pulses allows an unlimited gray scale capability.

Claim 21

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix being substantially free of polymer additive, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage, and wherein the driving voltage is a function of the width of a voltage pulse.

Claim 22

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix being substantially free of polymer additive, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage, and wherein the driving voltage is a function of the width of a voltage pulse.

Claim 23

The liquid crystal device of claim 19, wherein the first conductive layer is coated with a first amorphous boundary layer.

Claim 24

The liquid crystal device of claim 20, wherein the first amorphous boundary layer comprises a polyimide.

Claim 25

The liquid crystal device of claim 20, wherein the first amorphous boundary layer comprises a silane.

Claim 26

The liquid crystal device of claim 20, wherein the first amorphous boundary layer is in a random relationship with the liquid crystals in a planar direction.

Claim 27

The liquid crystal device of claim 19, wherein the second conductive layer is coated with a second amorphous boundary layer.

Claim 28

The liquid crystal device of claim 24, wherein the second amorphous boundary layer comprises a polyimide.

Claim 29

The liquid crystal device of claim 24, wherein the second amorphous boundary layer comprises a silane.

Claim 30

The liquid crystal device of claim 24, wherein the second amorphous boundary layer is in a random relationship with the liquid crystals in a planar direction.

Claim 31

The liquid crystal device of claim 19, wherein removing the driving voltage across the liquid crystal material causes the domain orientation to transform from one state to a different state.

Claim 32

The liquid crystal device of claim 19, wherein the driving voltage is a single voltage pulse.

Claim 33

The liquid crystal device of claim 29, wherein the single voltage pulse allows achievement of an unlimited gray scale capability.

Claim 34

The liquid crystal device of claim 19, wherein the driving voltage is applied by means of a matrix drive method wherein: V.sub.N =(V.sub.R -V.sub.S)/2; and wherein V N is the minimum cross-talk voltage, V R is the voltage pulse required to achieve the maximum zero field stable reflective state, and V S is the driving voltage having a value intermediate between V T and V C , and close to V C , wherein V T is the threshold voltage and V C is the critical voltage required to induce a phase change from cholesteric to nematic.

Claim 35

The liquid crystal device of claim 31, wherein V N is smaller than V T , and wherein V T is the threshold voltage.

Claim 36

The liquid crystal device of claim 29, wherein the speed of changing the domain orientation of the liquid crystal material is dependent on both the height of the driving voltage and the width of the voltage pulse.

Claim 37

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix being substantially free of polymer additive, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage comprising a succession of pulses.

Claim 38

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix being substantially free of polymer additive, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage comprising a succession of pulses.

Claim 39

The liquid crystal device of claim 34, wherein the succession of pulses allows an unlimited gray scale capability.

Claim 40

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage, and wherein the driving voltage is a function of the width of a voltage pulse, wherein the driving voltage is applied by means of a matrix drive method wherein: V.sub.N =(V.sub.R -V.sub.S)/2; and wherein V N is the minimum cross-talk voltage, V R is the voltage pulse required to achieve the maximum zero field stable reflective state, and V S is the driving voltage having a value intermediate between V T and V C , and close to V C , wherein V T is the threshold voltage and V C is the critical voltage required to induce a phase change from cholesteric to nematic.

Claim 41

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit, wherein an orientation of each of the multiple cholesteric domains can be changed by application of a driving voltage, and wherein the driving voltage is a function of the width of a voltage pulse, wherein the driving voltage is applied by means of a matrix drive method wherein: V.sub.N =(V.sub.R -V.sub.S)/2; and wherein V N is the minimum cross-talk voltage, V R is the voltage pulse required to achieve the maximum zero field stable reflective state, and V S is the driving voltage having a value intermediate between V T and V C , and close to V C , wherein V T is the threshold voltage and V C is the critical voltage required to induce a phase change from cholesteric to nematic.

Claim 42

The liquid crystal device of claim 36, wherein V N is smaller than V T , and wherein V T is the threshold voltage.

Claim 43

The liquid crystal device of claim 37, wherein the liquid crystal mix is substantially free of polymer additive.

Claim 46

The method of claim 39, wherein the combinations are achieved by subtraction.

Claim 47

The method of claim 40, wherein the subtraction results in alternating voltage.

Claim 48

The method of claim 39, wherein the first scan waveform comprises a polar square pulse having a first stage voltage of zero and a second stage voltage of V R , wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state.

Claim 49

The method of claim 39, wherein the second scan waveform comprises a polar square pulse having a first stage voltage of V R -V N and a second stage voltage of V N , wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state and V N is the minimum cross-talk voltage.

Claim 50

The method of claim 39, wherein the first data line waveform comprises a polar square pulse having a first stage voltage of V R and a second stage voltage of zero, wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state.

Claim 51

The method of claim 39, wherein the second data line waveform comprises a polar square pulse having a first stage voltage of V S and a second stage voltage of V R -V S , wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state and V S is the driving voltage having a value intermediate between V T and V C , and close to V C , wherein V T is the threshold voltage and V C is the critical voltage required to induce a phase change from cholesteric to nematic.

Claim 52

The method of claim 39, wherein the combinations result in alternating voltage.

Claim 53

The method of claim 39, wherein the first data line waveform, or the second data line waveform, or both the first data line waveform and the second data line waveform are applied to all pixels of the plurality of columns.

Claim 54

The method of claim 39, wherein the method comprises a series of repeatedly addressing successive scan lines.

Claim 55

The method of claim 39, wherein the method comprises a single relatively long voltage pulse.

Claim 56

The method of claim 39, wherein the method comprises a succession of shorter voltage pulses.

Claim 59

The method of claim 51, wherein the method comprises a series of repeatedly addressing successive scan lines.

Claim 60

The method of claim 51, wherein the method comprises a single relatively long voltage pulse.

Claim 61

The method of claim 51, wherein the method comprises a succession of shorter voltage pulses.

Claim 62

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit; and means to change the orientation of each of the multiple cholesteric domains, the means comprising: applying a first data line waveform or a second data line waveform to all pixels in at least one column of the plurality of columns; applying a first scan waveform to a row of pixels to be addressed; applying a second scan waveform to a remainder of the plurality of rows of pixels not to be addressed; and a combination of the first data line waveform and the first scan waveform causing the pixel to be addressed to achieve a reflecting state; a combination of the second data line waveform and the first scan waveform causing the pixel to be addressed to achieve a scattering state; either a combination of the first data line waveform and the second scan waveform, or a combination of the second data line waveform and the second scan waveform being ineffective to cause the remainder of the plurality of pixels to achieve either the reflecting state or the scattering state.

Claim 63

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; and a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit; and means to change the orientation of each of the multiple cholesteric domains, the means comprising: applying a first data line waveform or a second data line waveform to all pixels in at least one column of the plurality of columns; applying a first scan waveform to a row of pixels to be addressed; applying a second scan waveform to a remainder of the plurality of rows of pixels not to be addressed; and a combination of the first data line waveform and the first scan waveform causing the pixel to be addressed to achieve a reflecting state; a combination of the second data line waveform and the first scan waveform causing the pixel to be addressed to achieve a scattering state; either a combination of the first data line waveform and the second scan waveform, or a combination of the second data line waveform and the second scan waveform being ineffective to cause the remainder of the plurality of pixels to achieve either the reflecting state or the scattering state.

Claim 64

The liquid crystal device of claim 55, wherein the first conductive layer is coated with a first amorphous boundary layer.

Claim 65

The liquid crystal device of claim 56, wherein the first amorphous boundary layer comprises a polyimide.

Claim 66

The liquid crystal device of claim 56, wherein the first amorphous boundary layer comprises a silane.

Claim 67

The liquid crystal device of claim 56, wherein the first amorphous boundary layer is in a random relationship with the liquid crystals in a planar direction.

Claim 68

The liquid crystal device of claim 55, wherein the second conductive layer is coated with a second amorphous boundary layer.

Claim 69

The liquid crystal device of claim 60, wherein the second amorphous boundary layer comprises a polyimide.

Claim 70

The liquid crystal device of claim 60, wherein the second amorphous boundary layer comprises a silane.

Claim 71

The liquid crystal device of claim 60, wherein the second amorphous boundary layer is in a random relationship with the liquid crystals in a planar direction.

Claim 72

The liquid crystal device of claim 55, wherein the liquid crystal mix is substantially free of polymer additive.

Claim 73

The liquid crystal device of claim 55, wherein the combinations are achieved by subtraction.

Claim 74

The liquid crystal device of claim 65, wherein the subtraction results in an alternating voltage.

Claim 75

The liquid crystal device of claim 55, wherein the first scan waveform comprises a polar square pulse having a first stage voltage of zero and a second stage voltage of V R , wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state.

Claim 76

The liquid crystal device of claim 55, wherein the second scan waveform comprises a polar square pulse having a first stage voltage of V R -V N and a second stage voltage of V N , wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state and V N is the minimum cross-talk voltage.

Claim 77

The liquid crystal device of claim 55, wherein the first data line waveform comprises a polar square pulse having a first stage voltage of V R and a second stage voltage of zero, wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state.

Claim 78

The liquid crystal device of claim 55, wherein the second data line waveform comprises a polar square pulse having a first stage voltage of V S and a second stage voltage of V R -V S , wherein V S is the driving voltage having a value intermediate between V T and V C , and close to V C , wherein V T is the threshold voltage and V C , is the critical voltage required to induce a phase change from cholesteric to nematic and V R is the voltage pulse required to achieve the maximum zero field stable reflective state.

Claim 79

The liquid crystal device of claim 55, wherein the combinations result in alternating voltage.

Claim 80

The liquid crystal device of claim 55, wherein the means comprises a series of repeatedly addressing successive scan lines.

Claim 81

The liquid crystal device of claim 55, wherein the means comprises a single relatively long voltage pulse.

Claim 82

The liquid crystal device of claim 55, wherein the means comprises a succession of shorter voltage pulses.

Claim 83

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit; means to change the orientation of each of the multiple cholesteric domains, the means comprising: applying a first data line waveform or a second date line waveform to all pixels in at least one column of the plurality of columns, wherein the first data line waveform comprises a first polar square pulse having a first stage voltage of V R and a second stage voltage of zero, wherein the second data line waveform comprises a second polar square pulse having a first stage voltage of V S and a second stage voltage of V R -V S wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state; and V S is the driving voltage having a value intermediate between V T and V C , and close to V C , wherein V T is the threshold voltage and V C is the critical voltage required to induce a phase change from cholesteric to nematic; applying a first scan waveform to a row or pixels to be addressed, wherein the first scan waveform comprises a third polar square pulse having a first stage voltage of zero and a second stage voltage of V R , wherein V R is as above defined; applying a second scan waveform to a remainder of the plurality of rows of pixels not to be addressed, wherein the second scan waveform comprises a fourth polar square pulse having a first stage voltage of V R -V N and a second stage voltage of V N , wherein V N is a minimum cross-talk voltage; V T is as above defined; V N is lower than V T and being determined by subtracting a scan line voltage from a corresponding data line voltage; and wherein subtracting the first scan waveform from the first data line waveform causes the pixel to be addressed to achieve a reflecting state with an alternating voltage; subtracting the first scan waveform from the second data line waveform causes the pixel to be addressed to achieve a scattering state with an alternating voltage; and either subtracting the second scan waveform from the first data line waveform or subtracting the second scan waveform from the second data line waveform is ineffective to cause the remainder of the plurality of pixels to achieve either the reflecting state with an alternating voltage or the scattering state with an alternating voltage.

Claim 84

A liquid crystal device comprising: a first solid substrate having a first inner surface coated with a first conductive layer; a second solid substrate having a second inner surface coated with a second conductive layer; a substantially indefinite zero field multistable cholesteric liquid crystal mix located in a space between the first inner surface of the first solid substrate and the second inner surface of the second solid substrate, the liquid crystal mix comprising at least one liquid crystal and at least one twist agent forming multiple cholesteric domains, wherein each of the multiple cholesteric domains is a visible or near-visible reflective unit; means to change the orientation of each of the multiple cholesteric domains, the means comprising: applying a first data line waveform or a second date line waveform to all pixels in at least one column of the plurality of columns, wherein the first data line waveform comprises a first polar square pulse having a first stage voltage of V R and a second stage voltage of zero, wherein the second data line waveform comprises a second polar square pulse having a first stage voltage of V S and a second stage voltage of V R -V S wherein V R is the voltage pulse required to achieve the maximum zero field stable reflective state; and V S is the driving voltage having a value intermediate between V T and V C , and close to V C , wherein V T is the threshold voltage and V C is the critical voltage required to induce a phase change from cholesteric to nematic; applying a first scan waveform to a row or pixels to be addressed, wherein the first scan waveform comprises a third polar square pulse having a first stage voltage of zero and a second stage voltage of V R , wherein V R is as above defined; applying a second scan waveform to a remainder of the plurality of rows of pixels not to be addressed, wherein the second scan waveform comprises a fourth polar square pulse having a first stage voltage of V R -V N and a second stage voltage of V N , wherein V N is a minimum cross-talk voltage; V T is as above defined; V N is lower than V T and being determined by subtracting a scan line voltage from a corresponding data line voltage; and wherein subtracting the first scan waveform from the first data line waveform causes the pixel to be addressed to achieve a reflecting state with an alternating voltage; subtracting the first scan waveform from the second data line waveform causes the pixel to be addressed to achieve a scattering state with an alternating voltage; and either subtracting the second scan waveform from the first data line waveform or subtracting the second scan waveform from the second data line waveform is ineffective to cause the remainder of the plurality of pixels to achieve either the reflecting state with an alternating voltage or the scattering state with an alternating voltage.

Claim 85

The liquid crystal device of claim 75, wherein the first conductive layer is coated with a first amorphous boundary layer.

Claim 86

The liquid crystal device of claim 76, wherein the first amorphous boundary layer comprises a polyimide.

Claim 87

The liquid crystal device of claim 76, wherein the first amorphous boundary layer comprises a silane.

Claim 88

The liquid crystal device of claim 76, wherein the first amorphous boundary layer is in a random relationship with the liquid crystals in a planar direction.

Claim 89

The liquid crystal device of claim 75, wherein the second conductive layer is coated with a second amorphous boundary layer.

Claim 90

The liquid crystal device of claim 80, wherein the second amorphous boundary layer comprises a polyimide.

Claim 91

The liquid crystal device of claim 80, wherein the second amorphous boundary layer comprises a silane.

Claim 92

The liquid crystal device of claim 80, wherein the second amorphous boundary layer is in a random relationship with the liquid crystals in a planar direction.

Claim 93

The liquid crystal device of claim 75, wherein the liquid crystal mix is substantially free of polymer additive.

Claim 94

The liquid crystal device of claim 75, wherein the means comprises a series of repeatedly addressing successive scan lines.

Claim 95

The liquid crystal device of claim 75, wherein the means comprises a single relatively long voltage pulse.

Claim 96

The liquid crystal device of claim 75, wherein the means comprises a succession of shorter voltage pulses.