At&t Bell Laboratories

Bbc Brown, Boveri & Company, Limited

Lucent Technologies Inc.

Allan R Kmetz

Robert A Boie

Richard A Gottscho

Dwight W Berreman

John Robert Morris, Jr

Po-Yen Lu

William R Heffner

Richard H Krukar

A unitary display and sensing device integrates liquid crystal display module elements of a liquid crystal display module for detecting input on a flat panel display screen with the capability for digitizing the detected inputs. In accordance with an illustrative embodiment of the present invention, display elements of a liquid crystal display module are modified to sense input on the display screen. An electrical signal is applied to modified display elements of the liquid crystal display module so that contact with a surface portion of the display screen produces an output signal indicative of its location. The integrated display and sensing device is active matrix addressed for finger input, but may also incorporate display systems for active pen input.

Integrated liquid crystal display and digitizer having a black matrix

A matrix addressed, bistable liquid crystal optical display is disclosed. The display includes a liquid crystal twist cell which has at least two states which are stable in the presence of a single given holding voltage. A form of 3:1 matrix addressing is used in the display which enhances operational characteristics.

Matrix addressed bistable liquid crystal display

Liquid crystal elements are interconnected in an array of rows and columns, which are not independent of one another, and are addressed by pulsed signals which together reduce the number of leads N required to operate the display. The interconnection scheme includes connecting together the last column to the second row, the penultimate column to the third row, etc., and the first column to the last row. In one embodiment for randomly accessing the display, the addressing scheme divides a row-select signal and a column-select signal into two time-wise sequential subsets: a first subset which includes pulses of one polarity in the time slots corresponding to the elements in that row, and a second subset which includes pulses of either polarity depending on which elements in that column are to be turned on and which off. The coincidence of two pulses of opposite polarity applied to an element from the row-select and column-select signals in sufficent to turn on that element. Different addressing schemes are utilized in other embodiments for use as pseudo-analog pointer displays and bargraph displays.

Interconnection and addressing scheme for LCDs

A digital voltmeter device is disclosed which displays both the numerical value of a measured voltage and a visual representation of an input waveform. The device includes an electro-optical display matrix utilizing display elements arranged in lines and columns. In order to make maximum use of the display matrix for representing input waveforms, the peak-to-peak voltage of the input waveform is measured and utilized as a reference for an analog to digital converter having output signals which form the address signals for the display matrix. The peak values of the input waveform thus appear at the top and bottom of the display matrix respectively.

Digital voltmeter with electro-optical indication of the waveform

A method for addressing an electro-optical display device having a display comprising display elements which adjoin one another and are arranged in a row, each display element having two electrodes of two different types which are opposite one another and are separated from one another by a liquid crystal. The electrodes of the first type are connected to one another groupwise in an electrically conducting manner and the electrodes of the second types are connected to one another segment-wise in an electrically conducting manner. For pointer-type representation of data on a contrasting background, at least three rectangular signals which are of the same type but out of phase with one another are applied via an adressing circuit to the electrodes of the display elements in such a way that in-phase signals are applied to the group electrode and the segment electrode of at least one data-bearing element and signals which are out of phase with one another are applied to the group electrodes and segment electrodes of the elements forming the background, the signals being such that the voltage between the electrodes of each of the other elements is greater than the threshold voltage of the liquid crystal. Also disclosed are an addressing circuit and a display device for carrying out the abovementioned method.

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Chatham, NJ, United States of America

Allan R Kmetz