Thomson Consumer Electronics S.a.

Thomson Multimedia S.a.

Rca Thomson Licensing Corp.

Ruquiya I Huq

Sherman Weisbrod

Andrew G Dingwall

Dora Plus

A bi-directional shift register for scanning a liquid crystal display includes cascaded stages. A given stage includes an output transistor having a clock signal coupled thereto. A first input section is responsive to an output pulse of a second stage for generating a control signal that is coupled to the transistor to condition the output transistor periodically for operation in a conduction state when shifting in a first direction is selected. The input section is responsive to an output pulse of a third stage for periodically conditioning the output transistor to operate in the conduction state, when shifting in the opposite direction is selected. When the clock signal occurs and the transistor is conditioned for the operation in the conduction state, an output pulse is generated at an output of the given stage. A second input section is responsive to a corresponding output pulse of a corresponding stage for varying the control signal to condition periodically the output transistor for operation in a non-conductive state to disable the generation of the given stage output pulse, when the clock signal occurs.

Bi-directional shift register

A shift register for scanning a liquid crystal display includes cascaded stages. A given stage is formed with an input transistor switch that is responsive to an output pulse of a stage upstream in the chain of the cascaded stages. An output pulse of the given stage is produced in a pull-up transistor of a push-pull amplifier. A pull-down transistor is responsive to a control signal that tracks a variation of a threshold voltage of the pull-down transistor. A difference between the control signal and the threshold voltage is maintained small in a manner to reduce a change in a conductivity of the pull-down transistor when a drift in the threshold voltage of the pull-down transistor occurs.

Liquid crystal display driver with threshold voltage drift compensation

A video display driver applies a video signal to column electrodes of a liquid crystal display. The display driver includes a reference ramp generator and column data line drivers. Each data line driver includes a switching arrangement coupled to a first capacitance for storing a portion of the video signal in the first capacitance. A first terminal of the first capacitance is coupled to the reference ramp generator for combining a reference ramp signal with the stored video signal and for applying the combined signal to an input of a comparator. The comparator controls a transistor that couples a data ramp signal to a given column of the pixels. The reference ramp generator is coupled to the input of the comparator in a non-switched manner such that no switching transistor is interposed in a signal path between the reference ramp generator and the input of the comparator.

Data line drivers with common reference ramp display

A shift register for scanning a liquid crystal display includes cascaded stages. A given stage is formed with an input transistor switch that is responsive to an output pulse of a stage upstream in the chain of the cascaded stages. An output pulse of the given stage is produced in a pull-up transistor of a push-pull amplifier. A third transistor responsive to an output signal of a stage downstream of the given stage applies a control signal to a gate electrode of the pull-down transistor to render the pull-down transistor conductive.

Shift register with a transistor operating in a low duty cycle

A shift register for scanning a liquid crystal display includes cascaded stages. A given stage is formed with an input transistor switch that is responsive to an output pulse of a stage upstream in the chain of the cascaded stages. The input transistor switch charges a capacitance associated with a control electrode of a switched pull-up output transistor. The voltage in the capacitance conditions the output transistor for generating an output pulse when subsequently a clock signal occurs to the output transistor. A clamping transistor discharges the capacitance in a manner to prevent further generation of the output pulse when subsequent pulses of the clock signal occur. The clamping transistor is responsive to an output pulse of a stage downstream in the chain. An impedance that is developed at the control electrode is substantially higher after the clamping operation occurs and remain high for most of the vertical interval.

Phase clocked shift register with cross connecting between stages

A select line scanner for a liquid crystal display includes a plurality of cascaded stages each having an input terminal and an output terminal. Each stage includes a push-pull output circuit including pull up and pull down transistors driven with separate control signals. A further transistor has its conduction path coupled between the control electrode and a point of potential of sufficient value to turn the pull up transistor off. The control electrode of the further transistor is coupled to an output of a succeeding one of the cascaded stages to insure that the output of the respective stage cannot drift to an on state.

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Plainsboro, NJ, United States of America

Ruquiya I Huq