摘要:
A receiver having an interface arrangement for connection between said television circuit and a conditional access sub- system conveys data via a bus having a four frame bus cycle period with a bit rate corresponding to the line rate. During a first part of the bus cycle period data is conveyed from the receiver to the sub-system sequentially as follows: i. an address block of 1 byte with the unique address of the sub-system with which the receiver is in communication, ii. a status block of 1 byte providing status information for the following blocks in the first part, iii, iv, v. three data blocks each of 93 bytes and each containing an entitlement message, vi. a keying block of 1 byte conveying keyboard or remote control commands, and vii, viii. a further block of either 1 / 2 byte (vii) or 2 1 / 2 bytes (vii + viii) conveying frame count information. During the second and remaining part of the bus cycle period which comprises 30 or 28 bytes, depending on the length of the further block, data is transmitted from the sub-system to the receiver.
摘要:
A thermal imaging device comprising a ferroelectric or pyroelectric slab 1 bearing an infra-red-permeable common electrode 2 on one main surface and a signal electrode structure 3 on the opposite main surface. The signal electrode structure 3 is electrically connected to electrodes 12 of a circuit substrate 13 by means of solder bumps 14 fused to conductors 8 surrounded by a thermally insulating material. A problem in such thermally imaging devices is the heat conducted transverse to the longitudinal axes of the conductors 8 so that cross-talk occurs between adjacent sensing regions. The transverse heat conducting between adjacent conductors is reduced by using conductors which are each in the form of a metal coating 8 on a bore 7 in a respective pillar 10 of thermally insulating material, the pillars 10 being defined by channels 9.
摘要:
An electron beam addressed memory (EBAM) compris ing an envelope (10) within which are provided a source of an electron beam, a microcapacitor target (18) and means (24) for receiving, amplifying and detecting a secondary electron beam produced in response to scanning the target (18) by the electron beam in the read mode. In previous designs of EBAMs tungsten filaments or despenser cathodes have been used for producing the electron beam but if these are replaced by a cold semiconductor cathode (12) it is possible to obtain an electron beam of small cross-sectional size, having a high current density and can be switched on and off at frequencies up to at least 30MHz. The means for receiving, amplifying and detecting the secondary electrons produced in the reading operation comprises in the embodi ment illustrated an annular microchannel plate electron multiplier (24) disposed about, and coplanarly with, the target (18).
摘要:
The invention relates to methods of making colour selection deflection electrode structures for use in colour 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 colour 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. by etching, to define the required deflection electrodes (3) together with margins (7, 8) and interconnecting supporting strips (4, 5), bonding the two sheets together using an insulative bonding glass material with respective electrodes thereof in registration to form an integral assembly, and rotating the electrodes (3) through around 90° with respect to the plane of the sheets. Spacing elements determine spacing between opposed electrodes and margins.
摘要:
A pyroelectric infra-red radiation detector which is particularly suited to automated assembly comprises a pyroelectric detector element (1) mounted in a housing (4) having a window (5) transparent to infra-red radiation. Electrically conductive leads (6,7,8), e.g. in a single-in-line configuration, extend through a base portion (9) of the housing for making external electrical connections to the detector. Lead (8) comprises an extended portion (8b,8c,8d) within the housing providing a cantilever support (8d) to which the detector element (1) is fastened. The leads (6,7,8) may all be formed from portions of a unitary lead frame. A second differentially connected pyroelectric detector element (2) may be fastened to another cantilever support (16b) formed by a portion of the same lead frame. The cantilever supports (8d,16b) preferably extend from an insulating block (11) which encapsulates an associated electrical component (18) and which also provides support for the detector elements.
摘要:
@ An infra-red intruder detection system has two separate channels A and B each having its own pyroelectric detector device (10A, 10B) and threshold level comparators (22A, 23A, 22B, 238) responsive to dual polarity pyroelectric voltage outputs produced by the associated detector device as a result of an intruder-related infra-red image moving thereacross. A logic circuit (25) analyses the comparator outputs and responds to the identification of particular intruder-indicative sequences of comparator outputs in both channels to generate an alarm and/or switching output (27). The logic circuit may also identify shock-induced comparator outputs. The system offers a high intruder detection capabilitiy with immunity from false triggering.
摘要:
In a receiver for a C-or D-MAC Packet television signal the bits of a packet from the first subframe (DATA 'A') are multiplexed with the bits of a correspondingly positioned packet in the second subframe (DATA 'B') and applied to a data line of a packet bus so that the bits from the two packets alternate (DATA).
摘要:
A high mobility p channel semiconductor device (such as a field-effect transistor) is formed suitable for operation at room temperature, for example in a circuit with an n channel device. Whereas hole modulation doping both in single heterojunction and in heterostructure quantum well devices provides a significant increase in hole mobility only at cryogenic temperatures, the present invention employs less than 5nm wide and very deep quantum wells 1 (about 0.4 eV and deeper) to reduce the effective mass of "heavy" conduction holes for motion in the plane of the quantum well 1. Hole mobilities at 300 degrees K are obtained in excess of 2.5 times those in bulk material of the same narrow bandgap semiconductor as used for the quantum well 1. In a particular example such a quantum well 1 is formed of GaAs (or GaInAs) between AlAs barrier layers 2.
摘要:
0 An r.f. power amplifier, typically a high efficiency, class E amplifier in which a reactive load circuit (18) is connected to a semiconductor switching device (10), the load circuit being designed to have the required input load angle and loaded Q so that the voltage across the device (10) goes to zero with zero slope before it switches on and passes current, is provided with a step recovery diode (32) connected to the device (10) to limit the voltage swing across the device (10) with no significant loss of efficiency. This allows the voltage-handling capability required of the device to be reduced or the amplifier output power to be increased by increasing the supply voltage.
摘要:
@ A colour-display picture tube display screen was made by providing a display screen substrate with a layer of a photosensitive composition which becomes sticky upon exposure to light. A black film matrix pattern and patterns of phosphor elements were formed on the photosensitive composition layer by imagewise exposing the layer to light in accordance with respective patterns of the black film matrix and of the respective phosphor elements, dusting the exposed layer with cobalt oxide particles and with particles of the respective phosphors, and blowing off the non-adhering particles. The photosensitive composition layer was then removed from the display screen substrate by condensing vapour of an organic solvent on the display screen structure so as to dissolve the material of the photosensitive composition layer, and continuing condensation of the solvent vapour until pure solvent falls off the substrate. During condensation of the solvent vapour the display screen is disposed so that the condensate falls off the substrate. The photosensitive composition is soluble in the solvent but the light-absorbing material and phosphors are insoluble in the solvent. The black film matrix and patterns of phosphor elements are fixed to the display screen substrate, for example, using an inorganic binder such as potassium metasilicate.