Liquid crystal driving and switching apparatus utilizing multivibrators and bidirectional switches

Claim 2

Apparatus as claimed in claim 2 further including in said circuit means at least one active circuit element in a circuit forming a clock signal generator of substantially constant frequency connected to control the reversing of connections from said power terminals to be synchronized with said clock signal.

Claim 3

Apparatus as claimed in claim 1 wherein said circuit connected to reversibly establish connection between said power terminals and said drive current bus and said current conductor causes the bidirectionality of current to be symmetrical within about 10 percent.

Claim 4

In a display device wherein a display cell has discrete portions which are rendered less transparent to generate an image which is a function of a plurality of input signals, the combination comprising a cell containing a liquid crystal material, a first electrode unit in said cell, a second electrode unit consisting of a plurality of electrode segments in said cell, and at least one integrated circuit device having a plurality of active circuit elements integrated therein and including a drive current bus, a plurality of bidirectional current switches responsive to said input signals each connected in series between a respective one of said electrode segments and said drive current bus, a current conductor connected to said first electrode unit, two low voltage DC primary power terminals and a plurality of current switches in a circuit connected to sequentially establish two different current connections from said power terminals to said drive current bus and said current conductor, the first of said connections connecting the first power terminal to said drive current bus and the second power terminal to said current conductor, the second of said connections connecting the first power terminal to said current conductor and the second power terminal to said drive current bus.

Claim 5

Apparatus as claimed in claim 5 further including in said integrated circuit device a plurality of active circuit elements forming a circuit having as inputs the control inputs for said display device and with outputs connected respectively to control said bidirectional current switches, said circuit thereby defining the functional relation between said display inputs and the reflective image.

Claim 6

Apparatus as claimed in claim 6 further including in said integrated circuit device at least one active circuit element in a circuit forming a clock signal genErator of substantially constant frequency connected to control the reversing of connections from said power terminals to be synchronized with said clock signal.

Claim 7

Apparatus as claimed in claim 5 wherein said circuit connected to sequentially establish two different current connections from said power terminals sequences the connections so that their time duration is about equal.

Claim 8

In a display device wherein a display cell has discrete portions which are rendered less transparent to generate an image which is a function of a plurality of input signals, the combination comprising a cell containing a liquid crystal material, a first electrode unit in said cell, a second electrode unit consisting of a plurality of electrode segments in said cell, a drive current bus, a plurality of current switches responsive to said input signals each connected in series between a respective one of said electrode segments and said drive current bus, a current conductor connected to said first electrode unit, two DC primary power terminals, and a circuit including a plurality of current switches connected to reversibly establish a current connection between respective ones of said power terminals and said drive current bus and said current conductor.

Claim 9

In a liquid crystal display of the type including a common electrode, a plurality of electrode segments and a layer of a liquid crystal material interposed between said common electrode and said electrode segments, said layer being capable of changing its response to light upon activation by a current, the improvement therewith of apparatus for activating said liquid crystal with a bidirectional current, comprising: a. a multivibrator circuit including first and second active devices each having a common electrode, an input electrode and an output electrode and feedback means coupling the output electrode of said first device to the input electrode of said second device and the output electrode of said second device to the input electrode of said first device, to enable said circuit to be selectively activated to any one of two states wherein the first state said first device is biased on and said second device is biased off and in a second state, said first device is biased off and said second device is biased on, b. first means coupled to at least one input electrode of said first and second active devices to selectively alternate said states at a desired rate, and c. second means for coupling one of said output electrodes of said first and second devices to said common electrode of said liquid crystal, and said other output electrode to at least one of said electrode segments to bidirectionally activate said liquid crystal according to said desired rate.

Claim 10

The apparatus according to claim 10 wherein said multivibrator circuit is a bistable multivibrator curcuit.

Claim 11

The apparatus according to claim 10 wherein said multivibrator circuit is an astable multivibrator circuit.

Claim 12

In a liquid crystal display of the type including a common electrode, a plurality of electrode segments and a layer of a liquid crystal material interposed between said common electrode and said electrode segments, said layer being capable of changing its response to light upon activation by a current, the improvement therewith of apparatus for activating said liquid crystal with a bidirectional current, comprising: a. a multivibrator circuit having a first and second output terminal of the type providing a first given rectangular waveshape at said first output terminal of an amplitude varying between a first DC level and a second DC level which second level is relatively at reference potential, and at second output terminal providing an analagous waveform of an amplitude at said second DC level when said first waveshape is at said first level and at a said first DC level when said first waveshape is at said second DC level, and b. means coupling said first output terminal to said common electrode of said liquid crystal and said second output terminal to at least one of said electrode segments to cause a bidirectional current to flow through said liquid crystal according to said first and second waveshapes.

Claim 13

In a display of the type utilizing a liquid crystal having a common electrode, a plurality of segment electrodes and a liquid crystal material located between said common electrode and said segment electrodes, the improvement in combination therewith of apparatus for providing a bidirectional current flow through said liquid crystal to activate the same, comprising: a. a multivibrator circuit having a first and second output terminal for providing a first waveform at said first terminal of an amplitude alternately varying between a first DC level and a second DC level, which second level is relatively at reference potential, and a second waveform at said second terminal which alternately varies opposite to said first waveform whereby when said first waveform is at said first DC level, said second waveform is at said second DC level, b. means coupling said first output terminal of said multivibrator to said common electrode of said liquid crystal, c. means including a bidirectional current switch of the type exhibiting a low impedance in a first state upon activation of said switch by a control signal, and a high impedance in a second state, said switch coupled in series between at least one of said segment electrodes and a point of reference potential, and d. control means coupled to said switch for providing said control signal to cause said switch to exhibit said low impedance state to provide a bidirectional current return for said segment electrode.

Claim 14

Apparatus for driving a display of the type including a liquid crystal having at least two electrodes and a liquid crystal material between said electrodes, said apparatus comprising: a. first and second active devices, each having an input, output and common electrode, b. means coupling said common electrode to a point of reference potential, c. first feedback means coupling said output electrode of said first device to said control electrode of said second device, and second feedback means coupling said output electrode of said second device to said control electrode of said first device to cause said active devices to form a composite multivibrator circuit wherein alternately when one of said first and second devices is biased on, said other of said first or second devices is biased off, d. means coupling said output electrode of said first device to one of said electrodes of said liquid crystal and said output electrode of said second device to said other electrode of said liquid crystal to cause a signal to be developed across said liquid crystal according to the states of said active devices, and e. means coupled to at least one of said control electrodes of said active devices to determine the rate at which said devices are biased on and off.