Abstract

Provided is a method for driving a dot-matrix display using a bistable nematic liquid crystal. At a low temperature, a negative side drive mode (Mode-G) is selected to perform a drive control with a higher voltage efficiency, and at room temperature or a high temperature, a positive side drive mode (Mode-E) is selected to perform a drive with a lower current consumption. When driving at a small amplitude at a high temperature, modes (Mode-F, Mode-H) in which the output voltages of common terminals and segment terminals change at a small amplitude are selected to minimize an increase of the resistance in saturation of the output transistor. The selective use of the drive modes makes it possible to carry out rational drive in accordance with the characteristics of a bistable manetic liquid crystal panel.

IPC Classes  ?

• G02F 1/133 - Constructional arrangementsOperation of liquid crystal cellsCircuit arrangements
• G02F 1/139 - Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulatingNon-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent
• G09G 3/20 - Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix
• G09G 3/36 - Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix by control of light from an independent source using liquid crystals

Abstract

The present invention relates to a method of addressing a bistable matrix screen, in which the following two steps are repeated iteratively: A. a perturbation signal (Sp = VL - VC) is applied to each pixel of a marking zone for a time t1, said perturbation signal being greater than a threshold signal so that each pixel of the zone exits its initial stable state, said perturbation signal being less than a switching signal so that each pixel of the zone having one of the stable states as initial state does not flip into the other stable state, each pixel of the zone then being in a perturbed state intermediate between the two stable states, and then B. no signal is applied to each pixel of the zone for a time t2 so as to allow each pixel of the zone to return to its initial stable state.

IPC Classes  ?

• G09G 3/36 - Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix by control of light from an independent source using liquid crystals

Abstract

The invention relates to a method for making bistable nematic liquid-crystal devices including a nematic liquid-crystal layer (30) provided between two plates (20, 10), each plate including a blade (21, 11), an electrode (22, 12) and a nematic liquid-crystal alignment layer (24, 14), wherein at least one of the alignment layers has low zenith anchoring for said liquid crystal, a low pretilt and an average or strong azimuth anchoring, and wherein said at least one of said alignment layers (24, 14) is obtained by depositing a solution containing a polymer, said polymer being a copolymer or a terpolymer derived from vinyl chloride and vinyl ethers, the solution further including an additive selected from the group consisting of aromatic polyimides, precursors of the aromatic polyamic acid type, or a mixture of these compounds.

IPC Classes  ?

• G02F 1/1337 - Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers

Abstract

The present invention provides a nematic liquid crystal composition suitable for a bistable nematic liquid crystal display. A bistable nematic liquid crystal display having a wide nematic phase temperature range and operating temperature range can be obtained by using a nematic liquid crystal composition comprising at least 20% by weight of a specific liquid crystal compound (A) having a polar group and 5 to 50% by weight of a specific liquid crystal compound (B) not having a polar group, along with comprising, in the compound (B), at least 3% by weight of a specific liquid crystal compound having a alkenyl group.

IPC Classes  ?

• C09K 19/42 - Mixtures of liquid crystal compounds covered by two or more of the preceding groups

Abstract

A nematic liquid crystal composition of the present invention includes at least 20% by weight of one, or two or more compounds selected from compound group A; and 5 to 50% by weight of one, or two or more compounds selected from compound group B, wherein the relative proportions of the above-mentioned compounds used in the nematic liquid crystal composition is determined to simultaneously obtain the specific physical characteristics for the composition, and an anchoring breaking voltage U阳/4 is less than or equal to 25 V when the product (ﶴn ⋅ d) of the refractive index anisotropy (ﶴn) at 20° and the thickness (d) is 140 nm and the liquid crystal composition is confined between two substrates for a bistable nematic liquid crystal display in which at least one of the substrates have a weak zenithal anchoring force.

IPC Classes  ?

• C09K 19/42 - Mixtures of liquid crystal compounds covered by two or more of the preceding groups
• C09K 19/44 - Mixtures of liquid crystal compounds covered by two or more of the preceding groups containing compounds with benzene rings directly linked
• C09K 19/46 - Mixtures of liquid crystal compounds covered by two or more of the preceding groups containing esters

Abstract

The invention relates to a method for controlling a liquid crystal display, comprising a matrix of pixels arranged in crossed lines and columns and in which a switch in the state of the liquid crystal molecules, controlled by application of an electric control signal between two electrodes (50, 52) enclosing each pixel, which brings about a flow in a given direction (18), the pixel addressing being carried out by a line by line addressing either in a single step or in two steps, the first step comprising a collective addressing of at least a part of the screen in a given single texture, followed by a second step of line by line addressing, characterised in comprising, for controlling the switching of at least some of the pixels (P), a step for application to at least one adjacent pixel (58) of auxiliary electric signals wherein, depending on the direction of flow of the pixel (P) the switching of which is to be controlled, the rising or falling fronts of the auxiliary signals are temporally advanced in relation to or simultaneous with the active falling front of the electric control signal with a time offset of between 0 and several tens of microseconds at ambient temperature, such as to promote the switching of said pixel (P) for control, said auxiliary electric signals being applied in the second step when the addressing is in two steps. The invention further relates to a display.

IPC Classes  ?

• G09G 3/36 - Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix by control of light from an independent source using liquid crystals
• G02F 1/139 - Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulatingNon-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent

Abstract

The invention relates to a method for controlling a liquid crystal display, comprising a matrix of pixels arranged in crossed lines and columns and in which a switching of the state of the molecules of liquid crystals, controlled by application of an electric control signal between two electrodes (50, 52) enclosing each pixel which brings about a flow in a given direction (18), characterised in comprising, for controlling the switching of at least some of the pixels (P), a step of applying to at least one adjacent pixel (58), according to the direction of flow in a pixel (P) the switching of which is to be controlled by the electric control signal, auxiliary electric control signals, the amplitude of which are less than the anchoring break voltage, the rising or falling fronts of which are temporally in advance of or coincident with the falling active front of the electric control signal, such as to promote the switching of said pixel (P) for control. The invention further relates to a display.

IPC Classes  ?

• G09G 3/36 - Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix by control of light from an independent source using liquid crystals
• G02F 1/139 - Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulatingNon-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on orientation effects in which the liquid crystal remains transparent