Abstract: Liquid crystal display (LCD) devices are becoming more widespread in use because of low power requirements, but such devices are expensive to mount singly at present, being restricted for economy reasons to strips of devices. Elastomeric members are also becoming more widespread in use as a switching member in telephone key pads. The present invention provides a simple and inexpensive mounting of LCD devices individually, in association with switching keys. The key is formed by one protrusion on the elastomeric member. The LCD device is mounted in a recess on the top of another protrusion associated with the key protrusion. Conductive paths through the device mounting protrusion connect at their bottom ends with conductive paths and at the top ends with contacts on the LCD device.

Abstract: A mounting for line cards on circuit boards, as used in telecommunications systems comprises a molded plastic frame having a plurality of mounting positions for ceramic circuit members. Each position comprises two parallel, spaced guide and support members having upper and lower guide formations spaced along each guide and support member. There is a plurality of substrate holders, a holder for each position, each holder having a flat support surface with upstanding projecting members at front and rear ends, with undercuts for reception of a ceramic circuit member or substrate. Each holder has a front member extending normal to the support surface and has a latching and ejecting member at the front end. The frame also has support and guide formations at a rear end for attachment of a circuit board.

Abstract: A line switch assembly for a telephone switch has a unitary switch having a base within which are cantilevered contacts and a cap over the base, the cap having cam formations which actuate the contacts on reciprocal movement of the cap. An actuating member rests on the cap and has an extension with a rib which extends up into a recess in the top housing of the telephone set, the recess being one which accepts one of the handset transducers. Pressure on the rib pivots the actuating member and depresses the cap. The switch is a preassembled unit and is normally mounted on a circuit board carrying other components. A reduced number of components and quicker and easier assembly give a relatively high cost reduction.

Abstract: Communications terminals, such as telephone sets and additional terminals for particular services, are connected together by a connecting member which is attached to each terminal. Conveniently a recess is formed in each side wall of a terminal, the recesses being contiguous when two terminals are positioned side-by-side. A connecting member is positioned in the contiguous recesses, with hook-shaped members extending up through apertures in a top wall of the recesses and extending over, and preferably in close contact with the top wall. The connecting member is attached by pushing the hook-shaped members through the apertures and then sliding it relative to the terminals. The recesses can be wedge-shaped, the connecting member having a similar shape to fit in the recesses.

Abstract: Where several telephone sets are connected to a single telephone line, it would be convenient to have a visual indication that the line is in use, to avoid lifting a handset to see if there is a conversation, for example. A circuit is installed across the telephone line, the circuit having a voltage divider connected between Tip and Ring, a first transistor with its base connected to the center of the voltage divider, a second transistor with its base connected to the collector of the first transistor and a third transistor having its base connected to the emitter of the second transistor, with a light emitting device connected between either Tip or Ring conductor and the collectors of the second and third transistors. The light emitting device can be a light emitting diode. An optical coupler cooperative with the light emitting device can be used to turn on power to light emitting devices in all the telephones, from a separate power source.

Abstract: To obtain acceptable arc percussion welding of tin plated copper pins to thin brass strip members, the tin must be prevented from becoming trapped in the weld zone and gaseous and other forms of material also being trapped. By giving the end of a pin a smooth, hemispherical profile, the plasma arc is initiated at the center of the pin end and progressively moves radially outwards. This melts the tin plate layer and the tin is caused to flow radially outwards from the weld zone. The copper of the pin and brass of the strip then melt slightly and on impact welding is achieved. The outward flow of tin also assists in causing other undesirable elements being removed from the weld zone.

Abstract: A connector has socket-type terminals, each terminal having a main body part from the front end of which two arms project, as cantilevers. The inner part of each arm is curved, generally arcuate, and the outer part of each arm extends generally straight and inclined away from each other. A contact position is formed at the junction between the inner and outer part. Such terminals are housed in slots in a plug and a receptacle has pins which are inserted into the terminals. Cam surfaces on the receptacle engage with the free ends of the arms after partial insertion of the pins and press the arms together, pushing the contact positions into contact with the pins. A low insertion force is obtained.

Abstract: A multiple contact connector having a low profile has a bottom member for attachment to a large circuit board, the bottom member having a plurality of spaced parallel spring cantilever contact members. A top member is attached to an edge of another circuit board, for example a smaller board, the top member having a plurality of spaced parallel contact members having top and bottom legs, the top legs of the contact members making contact with the smaller board circuit pattern and the bottom legs contacting the cantilever contact members of the bottom member. A spring member extends up from the bottom member and snaps over the top member.

Abstract: A dynamic telephone receiver which is capable of being used in association with hearing aids, has a flux coil positioned around the pole piece and magnet assembly. To minimize the strong magnetic leakage field radiated from the air gap, which can attract pins, paper clips and other ferrous metals a shunt can be provided at the face of the receiver. However, this also shunts or at least severely attenuates the AC field produced by the flux coil for inductive coupling to hearing aids. The shunt of this invention shunts only the leakage flux from the air gap with minimal effect on the AC field from the flux coil. The shunt is in the form of a cup, with a central aperture in the front face, surrounded by an annular ring which is connected to the outer wall of the cup by narrow arms. The inner circumference of the ring is formed down towards the magnet to form a lip which attracts stray flux from the air gap. The shunt also acts to hold the receiver assembly together.

Abstract: A multiple contact connector having a low profile has a bottom member for attachment to a large circuit board, the bottom member having a plurality of spaced parallel spring cantilever contact members. A top member is attached to an edge of another circuit board, for example a smaller board, the top member having a plurality of spaced parallel contact members of U shape, the top legs of the contact member making contact with the smaller board circuit pattern and the bottom legs contacting the cantilever contact members of the bottom member. A spring member extends up from the bottom member and snaps over the top member.

Abstract: A modular telephone jack has two parts, top and bottom, which assemble together by relative vertical movement. Flexible members extending down from the main body of the top part pass down over the sides of the bottom part. Inwardly projecting ribs on the flexible members snap over outwardly projecting ribs on the sides of the bottom part. A jack with the minimal vertical profile is provided and enclosing shrouds and sonic welding of joints are avoided.

Abstract: Printed circuit boards have copper contact pads cut from copper foil and bonded to the circuit board, followed by printing circuit patterns of conductive ink on the board, the pattern connecting with the contact pads. The contact pads are cut from a copper foil strip fed with the circuit board beneath a die. Bonding of the contact pads follows, then printing of the circuit patterns. Boards can be formed from strip material in which case the individual boards are cut from the strip material.

Abstract: In an entrance terminal for a telephone cable, each terminal has an integral cable conductor trough at one side, generally closed by a cover. End walls in the troughs have apertures therein the apertures breaking through the edges of the end walls of the troughs, forming gaps of a width less than the diameter of the apertures. Sleeves extend through the appertures in adjacent end walls of adjacent terminals. By axially sliding a sleeve upward, out of the apertures, it is possible to remove a terminal without disturbing the remainder, as conductors can be eased through the gaps.

Abstract: Mounting of leaded components on one side of a PCB and surface mounting components on the other side of the PCB creates problems. The pressure of the lead ends projecting through the PCB prevents the use of a mask for applying solder paste for the mounting of the surface mounting components. Attaching surface mounting components initially by adhesive prior to wave soldering also causes problems. In the present invention leaded components are inserted and the lead ends crimped. The board is then turned over, solder paste applied by individual applicator nozzles to the lead ends and to solder pads on the circuit pattern. The surface mounting components are then positioned with contact areas aligned with the solder pads and the whole reflow soldered. The process can be repeated for surface mounting components on the same side as the original leaded components, with or without the insertion of further leaded components on the same side as the original surface mounting components.

Abstract: Electret transducers, for example microphones, have a backplate which is metallized on one surface, the metallized surface forming one side of a capacitor. A frame sits on the metallized tape to hold the tape taut over the backplate. Metal connections are made to the backplate and frame to complete the circuit. The metallization is conventionally formed by vapor deposition of aluminum. This is a lengthy and relatively expensive process. Also the metallization can give rise to galvanic problems. The invention prints a pattern of conductive ink on the various parts. Good contact is obtained, galvanic action avoided and a reduction in manufacturing costs occurs. Simplified assembly is also obtained.