Abstract: In operation of an active matrix display device comprising an array of display elements (12), for example liquid crystal elements, each connected in series with an associated two terminal non-linear switching device (30), e.g. a MIM, between row and column address conductors (22,24), and row and column driver circuits (40,43) for applying selection signals to each row conductor in turn and data signals to the column conductors, the data signals are applied for part only of the row address period and a row selection signal commences prior to the data signal and while a reference potential is applied to the column conductors whereby during a row address period a display element is initially charged to a level approaching the lower end of the display element's operational range of voltages and thereafter charged to the required level according to the data signal. Vertical cross-talk is reduced and peak current density through the non-linear devices is kept low, thereby avoiding the risk of damage.

Abstract: The image sensor (1a) has a transparent substrate (2) supporting a two dimensional array (3) of photosensitive and switching elements (4) with switching signal conductors (5) and data signal conductors (6) connected to the photosensitive and switching elements (4) for enabling individual photosensitive elements to be accessed. The photosensitive and switching elements (4) and the conductors (5 and 6) are arranged such that at least half of the area of the image sensor is transparent during operation. Each photosensitive element is electrically coupled to a respective capacitor (7) for storing charge generated as a result of light being incident on the photosensitive element. The capacitors (7) are formed so as to be transparent and so as to occupy a significant part of the entire area of the array (3).

Abstract: A Fingerprint sensing device and a recognition system having a row/column array of sense elements which are coupled to a drive circuit and a sense circuit by sets of row and column conductors, respectively. The sense elements are actively addressable by the drive circuit. Each sense element contains a sense electrode and a switching device (e.g., a TFT) for active addressing of that sense electrode. The sense electrodes of the sense elements are covered by insulating material adapted for receiving, directly thereon or on respective conductive pads overlying the sense electrodes, a finger. Capacitances resulting from individual finger surface portions in combination with sense electrodes are sensed by the sense circuit by applying a potential to the sense electrodes and measuring charging characteristics. In the fingerprint recognition system, an output from the sensing circuit is analyzed and characteristical data is compared with stored characteristical data for identification and verification purposes.

Abstract: A touch sensor array system comprises an array of sensor elements (12) each actively addressable by means of a switch device (16), for example two terminal devices such as diodes or MIMs, or TFTs, controlled by a driver circuit (22) to load a predetermined charge into a capacitor (14) of the element. Touching a sensor element dissipates this charge which is detected during a subsequent addressing stage by sensing particular charging characteristics with a monitoring circuit (24). With a row and column array, the elements (12) are addressed one row at a time at regular intervals using a row conductor (18) common to a row of elements. Each column of elements shares a column conductor (20) connected to the monitoring circuit. Various schemes are described enabling wired or isolated styli or a finger to be used as position designating means. The array is fabricated using thin film deposition techniques and high resolution arrays are easily achieved. The system can be used as a display overlay.

Abstract: In an addressable matrix device, for example an active matrix liquid crystal display device comprising a panel (10) having a row and column array of addressable picture elements (12), in which the elements are addressed via sets of row and column address conductors (14,16) by row and column drive circuits (24,26) providing sequential outputs, at least one of the circuits (24,26) consists of a sequence generator (28,29) comprising an electro-optic switching arrangement having light sensitive means including light sensitive elements (42), e.g. photodiodes, integrated on the panel and controlling the outputs of individual output stages (38) and light emitting means (35) including a plurality of light emitting elements (36) cooperating with the light sensitive elements, the light emitting elements being selectively operable to produce a sequence of outputs from the output stages, for example in order to scan the row address conductors.

Abstract: In a picture display device with pixels (12) which are driven via active elements (15), non-uniformities in the electrical behaviour of the active elements are obviated by driving the device in a reset mode.

Abstract: An active matrix addressed liquid crystal display system suitable for TV purposes, driven by applying to one of the conductors associated with each display element drive signals comprising a selection signal portion for setting a display condition followed by a sustain signal portion for sustaining that condition for an interval prior to receipt of the next selection signal, the magnitude of the sustain signal is decreased over its duration, thereby avoiding vertical cross-talk problems or the need to increase the number of diode structures. The sustain signal is decreased gradually, either continuously or in steps, so as to minimise the mean voltage across the non-linear element, and preferably in accordance with the decay time constant of the liquid crystal material of the display element.

Abstract: An active, matrix addressed display device comprising an array of display elements (37), e.g. liquid crystal display elements, each connected in series with a diode ring type non-linear device (31) between associated row and column address conductors (34, 35). The non-linear device comprises two parallel conduction paths each containing at least three series-connected diode elements (e.g. A1-E1, A2-E2) which permit current flow in a respective direction. The conduction paths share one or more intermediate diode elements (e.g. B1 or B1-D1). The one or more intermediate diode elements may be interconnected, either individually or as a group, in parallel with diode element(s) (e.g. B2 or B2-D2 respectively) of the other conduction path thereby providing alternative branches for fault tolerance but using fewer diode elements than usual for such purposes. Alternatively, the one or more intermediate diode elements (e.g.

Abstract: In order to reduce contrast degradation in an electrostatically scanned flat cathode ray tube having a channel plate electron multiplier, due to back-scattered electrons entering channels remote from their origin, a coating of a material having a low back-scatter coefficient is applied over the input of the electron multiplier between the apertures therein. The surface texture of the material should be microscopically rough. The material can be applied to the first dynode or to an electrode electrically and physically connected to the first dynode. The acceptance angle of the channel plate electron multiplier may also be restricted.

Abstract: In order to reduce contrast degradation in an electrostatically scanned flat cathode ray tube having a channel plate electron multiplier due to back-scattered electrons entering channels remote from their origin, steps are taken to restrict the acceptance angle of the channel plate electron multiplier. In one arrangement means are provided on the input surface to restrict the angle of entry to a range normally associated with the addressing electron beam. In another arrangement the ready emission of secondary electrons is restricted to a predetermined arcuate portion of the input of each channel of the electron multiplier. In either arrangement stray electrons are unable to impinge upon the secondary emitting material in the channels and in consequence produce many fewer back-scattered electrons.

Abstract: A color display tube which has a channel plate electron multiplier for multiplying a low voltage, low current electron beam and thereby obtaining an amplified output beam for producing an image on a screen formed of a plurality of different phosphors arranged as dots, each of which is surrounded by at least one ring. In order to form the output beam into well defined dots and rings to obtain good color purity, the source-to-screen distance of the output beam is varied in a predetermined manner. A means for doing this comprises additional electrodes mounted on the output side of the electron multiplier.

Abstract: In order to prevent the walls of the envelope (10) of a flat panel display tube having a large area screen from imploding, supporting walls (22) are provided to divide the interior of the envelope into a plurality of modules. Each module has its own electron beam generating means (24) for producing a low voltage, low current, intensity modulated electron beam (26) which is directed vertically upwards. A laminated channel plate electron multiplier (28) is disposed across the module and extends substantially parallel to the front and rear walls (12, 14) of the envelope. A single column of channels in the electron multiplier (28) is illustrated. The spacing of the channels determines the vertical resolution of the image produced. In order to deflect the electron beam (26) into a particular channel, a plurality of deflector electrodes (30) are disposed on the rear wall (14).

Abstract: A color display system including a cathode ray display tube (10) of the kind which has an electron multiplier (16) arranged adjacent a luminescent screen (14) comprising a repeating pattern of three different color phosphor elements and pairs of color selection electrodes (38, 40) associated with each channel of the multiplier operable to control the direction of the electron beam from the channels for color selection purposes uses a switching bridge circuit comprising semiconductor switching device (52, 54, 56, 58), e.g. MOSFETs, connected between voltage supplies for switching the voltage applied to each one of the pair of electrodes between three respective levels in synchronism to achieve a predetermined color selection sequence. The semiconductor devices are controlled by synchronized waveforms from a pulse generating circuit (86) via optocouplers (88) enabling the switching bridge circuit to be floated at a high potential.

Abstract: In a display tube a laminated dynode channel plate electron multiplier (16) produces at its channel outputs (50) a current-multiplied beam (34) in response to an electron beam being scanned thereover which is accelerated towards a phosphor screen (14) comprising repeating groups of different color phosphor elements and selectively directed onto particular elements by color selection deflector electrodes (38,40) adjacent the channel outputs. To provide increased horizontal resolution capability the exits (50) of the apertures in the final dynode are elongate in shape, other dynodes having circular apertures, and arranged parallel to one another with their longer axes extending vertically to form a comparatively narrow horizontal width output beam. The final dynode aperture entrances may be similarly elongate or circular with the apertures having a re-entrant profile.

Abstract: The invention relates to methods of making color selection deflection electrode structures for use in color picture display tubes having a channel plate electron multiplier arranged adjacent a screen, the deflection electrode structure being disposed intermediate the multiplier and screen and consisting of pairs of elongate, rectangular electrodes aligned with rows of output apertures of the multiplier and operable to control the direction of an electron beam emanating from those apertures so as to impinge upon a selected one of a plurality of different color phosphors in repeating pattern comprising the screen. The methods involve the steps of forming slits (1) in a pair of thin metal sheets, e.g.

Abstract: A display tube of the kind in which a line-scanned, low-energy electron beam (32) is directed into a space between a planar array of elongate deflection electrodes (42) and the input side of a laminated dynode channel electron multiplier (44). The deflection electrodes are switched sequentially by driving means between two potential levels (V.sub.1, V.sub.2) so as to deflect and scan the incoming beam frame-wise over the multiplier input, the current-multiplied beam emanating from the multiplier being directed onto a screen (16) to produce a display. By ensuring that the beam acceleration voltage, Va, satisfies the relationship 1.3 Vs<Va<2 Vs, where Vs=V.sub.2 -V.sub.1, beam spot size at the multiplier input is maintained and Moiree patterning effects in the display are effectively suppressed. The multiplier input electrode and final anode of the electron gun are advantageously held at the higher (V.sub.2) of the switched potentials.

Abstract: A display apparatus which comprises a display tube having a channel plate electron multiplier and a penetron screen having an electrode (hereinafter termed the screen electrode) thereon by which an accelerating field is provided between the electron multiplier and the screen. In order to obtain rapid switching of the voltage applied to the screen electrode, a high voltage power supply has a thermionic valve included within the display tube envelope to shunt current to ground when switching from a high voltage to a low voltage. The anode and cathode of the valve are connected respectively to the screen electrode and the electron gun cathode. The valve may be a triode or tetrode. A feedback arrangement is provided which causes the voltage on the screen electrode to remain substantially constant in spite of variations in screen current.

Abstract: A deflection color selection system for a single beam channel plate display tube includes, within an envelope 10, a laminated dynode channel plate electron multiplier (16) having channels whose exit apertures are aligned in columns. An apertured extractor electrode (36) is mounted on and electrically insulated from an output face of the electron multiplier (16), the apertures (42) in the extractor electrode (36) being aligned with respective channels. A luminescent screen (14) spaced from the extractor electrode (36) includes patterns of phosphor elements (R, G, B) adapted to luminesce in different colors.

Abstract: In a channel plate electron multiplier having a stack of perforated conducting sheet dynodes insulated from one another, electrons incident on the input face of the stack which do not enter the channels give rise to unwanted secondary electrons which move transverse to the channels in the space in front of the stack. These secondary electrons enter channels remote from the point of incidence and thereby degrade the definition and contrast of an electron image transmitted by the channel plate. A layer of material having a low secondary electron emission, which may be on a sheet carrier, is provided on the stack input face.

Abstract: A method of forming an emissive coating on a dynode substrate. The method comprises the steps of vapor depositing a composite coating consisting of magnesium and aluminum onto the dynode substrate. A 50 to 500 angstrom thick layer of aluminum is vapor deposited over the composite coating and the aluminum layer is oxidized. The coated dynode is then activated by heating it in an oxygen atmosphere at a pressure of at least 5.times.10.sup.-6 Torr oxygen at a temperature between 270.degree. and 400.degree. C. The resulting secondary emissive coating contains from 1.5 to 90% by weight of magnesium. The coated dynodes are used in channel electron multipliers which are suitable for use in electron display tubes such as image intensifiers or color television display tubes.