Abstract: A liquid crystal display has a plurality of buffers 46 controlling a plurality of column lines. The buffers have a bias current control input 47 which is controlled, in the example by timing circuitry 50, to current during the row period for writing to each row of pixels. In particular, the row period may be divided between a drive period with a high buffer bias current and a voltage maintenance period with a lower buffer bias current.

Abstract: An active matrix electroluminescent display device in which the drive current through an electroluminescent display element (20) in each pixel (10) in a drive period is controlled by a driving device (22) based on a drive signal applied during a preceding address period and stored as a voltage on an associated storage capacitor (36). In order to counteract the effects of display element ageing, through which the light output for a given drive signal level diminishes over time, the pixel includes electro-optic discharging means (40) coupled to the storage capacitor and responsive to the display element's light output to leak stored charge and to control the integrated light output of the display element in the drive period. For improved control, the discharging means is arranged to rapidly discharge the capacitor at a controlled point in the drive period, upon the drive of the display element falling to a low level. A photoresponsive transistor can conveniently be utilised for this purpose.

Abstract: In an active matrix LC display device having an array of display elements (12) addressed via respective transistors (11) connected to sets of row address conductors (14) to which selection pulses are applied in sequence and column address conductors (16) to which data signals are applied, and a storage capacitor (18) connected between each display element and a row conductor adjacent that to which its associated transistor is connected and which is operable in a capacitive coupling drive mode in which a step level in the waveform applied to each row conductor contributes to the final display element voltage, the row drive waveform applied to each row conductor includes a step level both before and after the selection pulse. Through this, the vertical scanning direction used can readily be reversed and an advantageous dot-inversion drive scheme can be employed.

Abstract: A method of driving an active matrix liquid crystal display in a partial display mode is provided, together with a display operable in accordance therewith. A live portion (4) of the display is driven to display image data (6) and a dormant portion (8) is driven to display a substantially constant grey scale level output. The method comprises applying a signal (40) to each of the column address conductors (18) associated with the dormant portion (8) which comprises a combination of a signal substantially the same as the signal (14) applied to the counter electrode and kickback correction, such that the resultant kickback correction applied to each of the picture elements associated with the dormant portion (8) substantially corresponds to the grey scale level of the dormant portion. This serves to reduce the power consumption of the dormant portion (8), whilst avoiding the application of a substantial DC across the picture elements of the dormant portion (8).

Abstract: A data input system is described comprising a surface 10, pen 12 and a plurality of transducers 14. The surface has a structure 10 such that when the pen 12 is moved across the structure 10, vibration is generated. This is detected by the transducers and the position of the pen 12 on the surface 10 is calculated. In the preferred embodiment of the invention the structure of the surface 10 varies across the surface 10. This means vibration signal waveforms may be associated with specific regions of the surface making identification of the pen location easier.

Abstract: An active matrix LC display device comprises an array of display elements (10) driven via sets of row and column address conductors (14, 16) connected respectively to a row drive circuit (30) operable to select each row in turn and a column drive circuit (35) for providing respective data signals for the display elements of a selected row and which comprises a multiplexing circuit arranged to address groups of column address conductors (16) in succession during a row address period. To avoid, or reduce, unwanted display artifacts arising from the use of a multiplexing circuit, the column drive circuit (35) is arranged to charge at least the last column address conductor in a group in at least two separate charging periods with the second charging period occurring after a charging period of the next group in the sequence.

Abstract: An active matrix electroluminescent display device has an array of current-driven electroluminescent display elements (20), for example comprising organic electroluminescent material, whose operations are each controlled by an associated switching means (10) to which a drive signal for determining a desired light output is supplied in a respective address period and which is arranged to drive the display element according to the drive signal following the address period. Each switching means comprises a current mirror circuit (24, 25, 30, 32) which samples and stores the drive signal with one transistor (24) of the circuit controlling the drive current through the display element (20) and having its gate connected to a storage capacitance (30) on which a voltage determined by the drive signal is stored. Through the use of current mirror circuits improved uniformity of light outputs from the display elements in the array is obtained.

Abstract: In an active matrix LC display device comprising a matrix array of display pixels (10) that are addressed via sets of row and column address conductors (14, 16) by row and column drivers (30, 35) operable to select each row of pixels in sequence and apply data signals to the selected row, the column address conductors are divided, preferably around the centre of the array, to define first and second display sub-matrices (50, 51) to which data signals are supplied by first and second column drivers (35A, 35B) respectively that operate substantially alternately. Through division of the column address conductors, each sub-matrix presents a lower capacitive load and consequently less power is consumed in driving the pixel columns.

Abstract: A capacitive sensing array device, particularly a fingerprint sensing array device, includes an array of sense electrodes covered by a layer of dielectric material defining a sensing surface over which, for example, a person's finger is placed in use. Grounding conductors are provided adjacent the sensing surface and extending alongside one or more edges of the sense electrodes. The material of the dielectric layer in the region of the grounding conductors at least has a non-linear I-V characteristic whereby electrostatic charges occurring in the device structure are conducted through this material to the grounding conductors. The grounding conductors may be buried in the dielectric layer and second electrodes provided on the sensing surface overlying respective sense electrodes and overlapping the grounding conductors.

Abstract: An active matrix electroluminescent display device has an array of current-driven electroluminescent display elements (20), for example comprising organic electroluminescent material, whose operations are each controlled by an associated switching means (10) to which a drive signal for determining a desired light output is supplied in a respective address period and which is arranged to drive the display element according to the drive signal following the address period. Each switching means comprises a current mirror circuit (30, 32, 38) in which the same transistor (30) is used to both sense and produce the required drive current for the display element (20) with the gate of the transistor being connected to a storage capacitance (30) on which a voltage determined by the drive signal is stored. This allows variations in transistor characteristics over the array to be compensated and improved uniformity of light outputs from the display elements to be obtained.

Abstract: An active matrix electroluminescent display device has an array of current—driven electroluminescent display elements (20), for example comprising organic electroluminescent material, whose operations are each controlled by an associated switching means (10) to which a drive signal for determining a desired light output is supplied in a respective address period and which is arranged to drive the display element according to the drive signal following the address period. Each switching means comprises a current mirror circuit (24, 25, 30, 32) which samples and stores the drive signal with one transistor (24) of the circuit controlling the drive current through the display element (20) and having its gate connected to a storage capacitance (30) on which a voltage determined by the drive signal is stored. Through the use of current mirror circuits improved uniformity of light outputs from the display elements in the array is obtained.

Abstract: A capacitive sensing array device, particularly a fingerprint sensing array device, includes an array of sense electrodes covered by a dielectric layer defining a sensing surface over which, for example, a person's finger is placed in use. Each sense electrode is associated with an overlying, electrically isolated, second electrode on the sensing surface. One or more adjacent conductor lines at a predetermined potential are also carried on the sensing surface, e.g. in the form of a grid surrounding and spaced from the second electrodes and the second electrode and/or its adjacent conductor line is shaped at a part thereof so as to encourage electrical flash-over at a reduced potential level at that part and prevent damage being caused by electrostatic charges carried by a person's finger.

Abstract: In a display device based on a TFT-matrix with capacitive coupling, the flicker is prevented by providing the selection lines with an auxiliary signal within a short time period before or after selection.

Abstract: A method of driving a matrix display device having an array of electro-optic display elements (12) each of which is connected in series with a two terminal non-linear device (15), such as a MIM, between associated row and column address conductors (16,17), in which the display elements are driven in a reset mode of operation by applying to the column address conductors data signals (D) and to the row address conductors selection signals (Vs) and reset signals (Va) to correct for non-uniformities in the characteristics of the non-linear devices, and in which in a row address period (T1) a data signal (D) applied to a column conductor is preceded by its inverse (D), a reset signal (Va) is applied during the application of the inverse data signal, and a selection signal (Vs+) is applied during the application of the data signal in the latter part of the row address period in order to minimize differences in ageing of the non linear devices.

Abstract: A matrix display device comprising a row and column array of display elements (14), e.g. LC display elements, each of which is connected in series with a two terminal non-linear device (15), such as a MIM, between associated row and column address conductors (16,17) and drive means (20,22,25) for applying drive voltages to the picture elements comprising a scanning signal circuit (20) and a data signal circuit (22) for applying selection signals and data signals respectively to the sets of address conductors, in which a sensing circuit (40) provides a control signal (V.sub.1) indicative of current flowing in one, or more, address conductor (16) of one set during the application of selection signals to that conductor which determines the drive voltages applied to the picture elements, preferably by adjustment of the selection signal level, so as to compensate for changes over time in the threshold characteristics of the non-linear devices. Four or five level scanning signal drive schemes may be used.

Abstract: An optical touch input device comprises an array of actively addressed sensing elements (18) for sensing a light input, e.g. from a light pen, each of which comprises a capacitor (25) which is charged periodically through operation of a switch device (24) and a discharge circuit, including a photosensitive device (28) and a further switch device (27) connected across the capacitor, which circuit in operation demonstrates an optical threshold characteristic whereby the capacitor (25) is discharged in response to the sensing elements being subjected to light which is at or above a predetermined intensity level so as to discriminate from ambient light. Elements written into are determined by detecting the charge stage of their capacitors. The sensing element array can be integrated with a matrix display device with the sensing elements (18) and display elements components (12) provided on a common support using thin film technology.

Abstract: In an active matrix display device having an army of electro-optic, e.g. liquid crystal, display elements (12) which are each connected in series with a two-terminal non-linear device (15), such as a MIM type thin film diode, between associated row and column address conductors (16,17), and are driven by a circuit, (20,22) to produce a display effect by applying a selection signal to each row address conductor in turn and data signals to the column address conductors, a selection signal comprising a voltage pulse signal whose magnitude is increased gradually and in a controlled fashion to a maximum selection voltage amplitude is used so as to reduce the extent of ageing in the non-linear devices and differential ageing effects on display elements driven to different levels over a period of use by reducing peak currents flowing through the non-linear devices. The rising edge of the selection pulse signal is suitably shaped, for example by ramping or stepping, for this purpose.

Abstract: The response rate of a liquid crystal display device is increased in that capacitive variations in the liquid crystal mixture caused by a different drive voltage or varying capacitances in drive transistors are taken into account in advance. If necessary, the required corrections are performed with a microprocessor, but they are preferably stored in advance in a look-up table.

Abstract: An active matrix liquid crystal display device in which an array of picture elements which include respective switching means, e.g. TFTs, are driven a row at a time by drive signals supplied via a set of row and a set of column address conductors. The device also includes an array of active addressed sensing elements each consisting of a photosensitive element, e.g. a thin film photoresistor or photodiode, a charge storage capacitor and a switching device, e.g. a TFT. The sensing element connected to respective row and column address conductors. The charge storage capacitors are periodically charged through operation of their associated switching devices by the drive signals and are selectively discharged via their associated photosensitive element when illuminated by, for example, a light pen.

Abstract: A matrix display device comprises a row and column array of picture elements (12) each of which consists of a display element (14), e.g. a LC display element, connected in series with a two-terminal non-linear device 15, such as a MIM, between associated row and column address conductors (16,17) to which selection and data signals are applied by a scanning signal drive circuit (20) and a data signal drive circuit (22) respectively, and a reference element circuit (34), comprising a non-linear device (35) in series with a capacitor (36), forming part of a feedback arrangement through which picture element drive voltages are controlled (25) so as to compensate for the effects of aging of the non-linear devices. The reference circuit is driven like the picture elements, with a scanning signal waveform and voltage signal (V.sub.A) applied to opposite sides, and the picture element drive voltages are adjusted in accordance with predetermined changes in the voltage across the capacitor (36).