EP0553727A2 — Ferroelectric liquid crystal device and treatment…

Claim 1

Independent Claim 98 words

A treatment method for a ferroelectric liquid crystal device, comprising: providing a ferroelectric liquid crystal device comprising a ferroelectric liquid crystal, and a pair of substrates sandwiching the ferroelectric liquid crystal and each having thereon an electrode for applying a voltage to the ferroelectric liquid crystal, the pair of substrates being provided with uniaxial alignment axes in directions which are substantially identical so as to provide a pretilt angle α of at least 10 degrees between a substrate boundary and liquid crystal molecules adjacent to the boundary; and applying an AC electric field to the ferroelectric liquid crystal.

Claim 2

Dependent Claim 49 words

A method according to Claim 1, wherein said ferroelectric liquid crystal is placed in an alignment state providing at least two stable states of optical axes which form an angle 2ϑa therebetween satisfying Ⓗ > ϑa > Ⓗ/2, wherein Ⓗ denotes a cone angle of the ferroelectric liquid crystal.

Claim 3

Dependent Claim 43 words

A method according to Claim 1, wherein said ferroelectric liquid crystal is placed in an alignment state satisfying H⃝ - δ < α , wherein Ⓗ denotes a cone angle and δ denotes a layer inclination angle, respectively, of the ferroelectric liquid crystal.

Claim 4

Dependent Claim 20 words

A method according to Claim 1, wherein the temperature of the device is changed during the AC electric field application.

Claim 5

Dependent Claim 30 words

A method according to Claim 4, wherein the temperature of the device is changed so as to heat and cool the ferroelectric liquid crystal within its smectic phase temperature range.

Claim 6

Dependent Claim 50 words

A method according to Claim 4, wherein said ferroelectric liquid crystal is placed in an alignment state providing at least two stable states of optical axes which form an angle 2ϑa therebetween satisfying H⃝ > ϑa > H⃝/2 , wherein Ⓗ denotes a cone angle of the ferroelectric liquid crystal.

Claim 7

Dependent Claim 43 words

A method according to Claim 4, wherein said ferroelectric liquid crystal is placed in an alignment state satisfying H⃝ - δ < α , wherein Ⓗ denotes a cone angle and δ denotes a layer inclination angle, respectively, of the ferroelectric liquid crystal.

Claim 8

Dependent Claim 100 words

A treatment method for a ferroelectric liquid crystal device, comprising: providing a ferroelectric liquid crystal device comprising a ferroelectric liquid crystal, and a pair of substrates sandwiching the ferroelectric liquid crystal and each having thereon an electrode for applying a voltage to the ferroelectric liquid crystal, the pair of substrates being provided with uniaxial alignment axes in directions which are substantially identical so as to provide a pretilt angle α of at least 10 degrees between a substrate boundary and liquid crystal molecules adjacent to the boundary; and heating and cooling the ferroelectric liquid crystal in its smectic temperature range.

Claim 9

Dependent Claim 33 words

A method according to Claim 8, wherein said uniaxial alignment axes provided to said pair of substrates intersect each other at an intersection angle ϑc satisfying: 20 degrees > ϑc > 0 degree.

Claim 10

Dependent Claim 130 words

A ferroelectric liquid crystal device, comprising: a ferroelectric liquid crystal, and a pair of substrates sandwiching the ferroelectric liquid crystal and each having thereon an electrode for applying a voltage to the ferroelectric liquid crystal, the pair of substrates being provided with uniaxial alignment axes in directions which are substantially identical so as to provide a pretilt angle α of at least 10 degrees between a substrate boundary and liquid crystal molecules adjacent to the boundary; wherein said liquid crystal is provided with a layer structure showing a diffraction peak area which is at least 70 % of that of the liquid crystal contained in a device which is identical to the above-mentioned device except for having an alignment control film comprising a polyimide represented by the following structural formula:

Claim 11

Dependent Claim 268 words

A ferroelectric liquid crystal device, comprising: a ferroelectric liquid crystal, and a pair of substrates sandwiching the ferroelectric liquid crystal and each having thereon an electrode for applying a voltage to the ferroelectric liquid crystal, the pair of substrates being covered with alignment control films of a polymer rubbed in directions which are substantially identical so as to provide a pretilt angle α of at least 10 degrees between a substrate boundary and liquid crystal molecules adjacent to the boundary; wherein said liquid crystal is provided with a layer structure providing a diffraction peak area of at least 9000 cps when measured with respect to a liquid crystal cell prepared in an equivalent manner, i.e., by providing a 80 µm-thick glass plate, coating the glass plate sequentially with a 1500 Å-thick indium tin-oxide film, a 900 Å-thick insulating film and a 200 Å-thick alignment control film of the same polymer and rubbing the alignment control film, applying the thus treated glass plate and another glass plate treated identically to each other to form a cell so as to provide a pretilt angle of at least 10 degrees, and filling the cell with the same ferroelectric liquid crystal in a liquid crystal layer thickness of 1.5 µm, under X-ray diffraction conditions including: X-ray output power: 15 kW (= 50 kV x 30 mA), divergence slit: 0.5 degree, scanning slit: 0.5 degree, light-receiving slit: 0.15 mm, sampling angle: 0.05 degree, scanning speed: 10 deg/min, analyzing rays: copper Kα rays, and irradiation area: 8.0 x 1.8 mm² as measured in case of the X-rays being incident perpendicularly to the glass substrate.

Claim 12

Dependent Claim 53 words

A device according to Claim 10 or 11, wherein said ferroelectric liquid crystal is placed in an alignment state providing at least two stable states of optical axes which form an angle 2ϑa therebetween satisfying H⃝ > ϑa > H⃝ /2 , wherein Ⓗ denotes a cone angle of the ferroelectric liquid crystal.

Claim 13

Dependent Claim 45 words

A device according to Claim 10 or 11, wherein said ferroelectric liquid crystal is placed in an alignment state satisfying H⃝ - δ < α , wherein Ⓗ denotes a cone angle and δ denotes a layer inclination angle, respectively, of the ferroelectric liquid crystal.

Claim 14

Dependent Claim 130 words

A ferroelectric liquid crystal device, comprising: a ferroelectric liquid crystal, and a pair of substrates sandwiching the ferroelectric liquid crystal and each having thereon an electrode for applying a voltage to the ferroelectric liquid crystal, the pair of substrates being provided with uniaxial alignment axes in directions which are substantially identical so as to provide a pretilt angle α of at least 10 degrees between a substrate boundary and liquid crystal molecules adjacent to the boundary; wherein said liquid crystal is provided with a layer structure showing a diffraction peak half-value width which is at most 1.5 times that of the liquid crystal contained in a device which is identical to the above-mentioned device except for having an alignment control film comprising a polyimide represented by the following structural formula:

Claim 15

Dependent Claim 269 words

A ferroelectric liquid crystal device, comprising: a ferroelectric liquid crystal, and a pair of substrates sandwiching the ferroelectric liquid crystal and each having thereon an electrode for applying a voltage to the ferroelectric liquid crystal, the pair of substrates being covered with alignment control films of a polymer rubbed in directions which are substantially identical so as to provide a pretilt angle α of at least 10 degrees between a substrate boundary and liquid crystal molecules adjacent to the boundary; wherein said liquid crystal is provided with a layer structure providing a diffraction peak half-value width of at most 2.5 degrees when measured with respect to a liquid crystal cell prepared in an equivalent manner, i.e., by providing a 80 µm-thick glass plate, coating the glass plate sequentially with a 1500 Å-thick indium tin-oxide film, a 900 Å-thick insulating film and a 200 Å-thick alignment control film of the same polymer and rubbing the alignment control film, applying the thus treated glass plate and another glass plate treated identically to each other to form a cell so as to provide a pretilt angle of at least 10 degrees, and filling the cell with the same ferroelectric liquid crystal in a liquid crystal layer thickness of 1.5 µm, under X-ray diffraction conditions including: X-ray output power: 15 kW (= 50 kV x 30 mA), divergence slit: 0.5 degree, scanning slit: 0.5 degree, light-receiving slit: 0.15 mm, sampling angle: 0.05 degree, scanning speed: 10 deg/min, analyzing rays: copper Kα rays, and irradiation area: 8.0 x 1.8 mm² as measured in case of the X-rays being incident perpendicularly to the glass substrate.

Claim 16

Dependent Claim 53 words

A device according to Claim 14 or 15, wherein said ferroelectric liquid crystal is placed in an alignment state providing at least two stable states of optical axes which form an angle 2ϑa therebetween satisfying H⃝ > ϑa > H⃝ /2 , wherein Ⓗ denotes a cone angle of the ferroelectric liquid crystal.

Claim 17

Dependent Claim 45 words

A device according to Claim 14 or 15, wherein said ferroelectric liquid crystal is placed in an alignment state satisfying H⃝ - δ < α , wherein Ⓗ denotes a cone angle and δ denotes a layer inclination angle, respectively, of the ferroelectric liquid crystal.

Claim 18

Dependent Claim 100 words

A ferroelectric liquid crystal device, comprising: a ferroelectric liquid crystal, and a pair of substrates sandwiching the ferroelectric liquid crystal and each having thereon an electrode for applying a voltage to the ferroelectric liquid crystal, the pair of substrates being provided with uniaxial alignment axes in directions which are substantially identical so as to provide a pretilt angle α of at least 10 degrees between a substrate boundary and liquid crystal molecules adjacent to the boundary; wherein said liquid crystal is provided with a layer structure including smectic layers which are disposed at a constant layer spacing between the substrates.

Claim 19

Dependent Claim 14 words

A device according to Claim 18, wherein said layer structure is a chevron structure.

Claim 20

Dependent Claim 71 words

A ferroelectric liquid crystal device, comprising: a pair of substrates having thereon scanning electrodes and data electrodes, respectively, and respectively provided with uniaxial alignment axes which are mutually parallel or substantially parallel, and a ferroelectric liquid crystal disposed between the substrates so as to provide a pretilt angle of at least 10 degrees and disposed in a layer structure including smectic layers which are disposed at a substantially constant layer spacing.

Claim 21

Dependent Claim 146 words

A ferroelectric liquid crystal device, comprising: a pair of a first substrate and a second substrate having thereon scanning electrodes and data electrodes, respectively, and each provided with a uniaxial alignment axis, and a ferroelectric liquid crystal disposed between the substrates, wherein said ferroelectric liquid crystal is placed in an alignment state such that liquid crystal molecules in the vicinity of a substrate boundary are oriented to have an inward or outward dipole moment depending on an electric field direction applied thereto, liquid crystal molecules in the vicinity of each substrate boundary show a substantially equal pretilt angle regardless of whether they have an inward or outward spontaneous polarization direction, and the liquid crystal molecules in the vicinity of the first substrate and the liquid crystal molecules in the vicinity of the second substrate show a substantially equal pretilt angle regardless of their spontaneous polarization direction.

Claim 22

Dependent Claim 82 words

A device according to Claim 20 or 21, wherein said ferroelectric liquid crystal is placed in a smectic layer structure providing an X-ray diffraction peak in terms of diffraction intensity versus layer inclination angle, which peak shows a half value width Γ h satisfying a relationship of 20 < Γ h /Γ₀ < 50 , wherein Γ₀ denotes a half value width of an X-ray diffraction peak given by the ferroelectric liquid crystal in a bulk state not confined in the device.

Claim 23

Dependent Claim 59 words

A device according to Claim 22, wherein the half-value width Γ h satisfies a relationship of 1 < Γ h /Γ₁ < 2 , wherein Γ₁ denotes half-value width of an X-ray diffraction peak given by the ferroelectric liquid crystal contained in a device of an identical structure except for showing a pretilt angle of at most 5 °C.

Claim 24

Dependent Claim 89 words

A device according to Claim 20 or 21, wherein said ferroelectric liquid crystal is placed in an alignment state satisfying H⃝ - δ < α , wherein Ⓗ denotes a cone angle and δ denotes a layer inclination angle and α denotes a pretilt angle, respectively, of the ferroelectric liquid crystal, and in an alignment state providing at least two stable states of optical axes which form an angle 2ϑa therebetween satisfying H⃝ > ϑa > H⃝/2 , wherein Ⓗ denotes a cone angle of the ferroelectric liquid crystal.

Claim 25

Dependent Claim 36 words

A device according to Claim 20 or 21, wherein the uniaxial alignment axes provided to said pair of substrates are identical in direction and intersect each other at an intersection angle ϑc (ϑc < 90 degrees).

Claim 26

Dependent Claim 36 words

A device according to Claim 20 or 21, wherein the uniaxial alignment axes provided to said pair of substrates are opposite in direction and intersect each other at an intersection angle ϑc (ϑc < 90 degrees).

Claim 27

Dependent Claim 18 words

A device according to Claim 20 or 21, wherein the uniaxial alignment axes have been provided by rubbing.

Claim 28

Dependent Claim 89 words

A device according to Claim 21, wherein said ferroelectric liquid crystal has smectic A phase on a higher temperature side than the chiral smectic phase and provides a pretilt angle α A in the smectic A phase which is substantially equal for liquid crystal molecules in the vicinity of the first substrate and for liquid crystal molecules in the vicinity of the second substrate, and the pretilt angle α A is substantially equal to the pretilt angle α C of the ferroelectric liquid crystal in the chiral smectic phase.

Ferroelectric liquid crystal device and treatment method therefor

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