Northern Telecom Limited

Other

James E Anderson

William P Trumble

Frederick Caldwell Livermore

Jerzy Borkowicz

Robin McIntyre

Leonard J Charlebois

John D Lee

Francis Y Hung

Michael J Coleman

Paul A Taylor

Gerzy Borkowicz

A solid-state surge protection device comprises a semiconductor chip sandwiched between two electrodes. A resilient sealing member or layer comprised of a thermoplastic or thermosetting resin extends around the periphery of the device, adhering to both electrodes, so as to seal the interface region between the chip and each electrode. The resin is a flexible, dielectric material which is not disrupted by heat generated under surge conditions in the device, is environmentally inert, and preferably remains compliant under extremely cold conditions. The electrodes of the device can move together into electric-conductive contact in the event of chip destruction, or can move back into contact with the chip if separated therefrom by an arc.

Packaged solid-state surge protector

An overvoltage protector for protecting equipment, especially telephone equipment, against high voltage surges such as are caused by lightning in the vicinity of the equipment or the cables to which it is connected, comprises one or more overvoltage protectors (42,58) mounted upon one face of an insulating support (18). A generally planar contact member (62) mounted upon the support member has a ground contact member (90) to make contact with a ground electrode (114) in the equipment to be protected and with each overvoltage protector. A spacer (60) of fusible plastics material extending between the contact member (62) and an interconnection (26) to one terminal (42A) of the protector melts when a sustained fault occurs. As the spacer melts, it permits an electrical connection between the contact member and the line to which the overvoltage protector is connected, effectively short-circuiting the line to ground. Overcurrent protection may be provided by means of a resistor (116) disposed in series with the line and located close to the plastics spacer so as to heat the spacer when an overcurrent occurs. In one case, the spacer comprises a film interposed directly between a pair of contacts which serve to short-circuit the protector. In another case, the spacer comprises a limb with relatively thin lateral projections which melt and shear. In both cases, the spacer preferably comprises high density, high molecular weight polyethylene.

Surge protector for telecommunications equipment

A solid-state surge protection device comprises a semiconductor chip sandwiched between two electrodes. A resilient sealing member or layer comprised of a thermoplastic or thermosetting resin extends around the periphery of the device, adhering to both electrodes, so as to seal the interface region between the chip and each electrode. The resin is a flexible, dielectric material which is not disrupted by heat generated under surge conditions in the device, is environmentally inert, and preferably remains compliant under exteremely cold conditions. The electrodes of the device can move together into electric-conductive contact in the event of chip destruction, or can move back into contact with the chip if separated therefrom by an arc.

A solid-state surge protection device comprises two electrodes between which is sandwiched a semiconductor chip. A resilient, annular, sealing member comprised of a thermoplastic resin extends around the periphery of the device and is adhered to both electrodes. The resin is a flexible, dielectric material which is not disrupted by heat generated under surge conditons in the device, and which is environmentally inert. The electrodes can be soldered to opposite surfaces of the chip.

The invention provides accessories for use with a rotary lawn mower in which the conventional bar having oppositely facing cutting edges is replaced with an accessory bar to which a variety of grass grooming accessories can be easily attached. The accessory bar can accommodate replaceable grass cutting elements, grass mulching elements and lawn power raking elements. The elements can be replaced without removing the accessory bar from the mower and are balanced to reduce vibration. Two of the accessories have cutting edges which are factory sharpened on relatively low cost elements, and thus can be discarded when blunt and replaced with new, low cost factory sharpened elements, thus maintaining balance. The rake accessory has a variation which permits a fine adjustment of vertical height of the rake above the lawn, to accommodate lawn mowers having coarse or no height adjustment.

Rotary lawn mower accessories

An overvoltage protection device, especially for telephone equipment and the like, comprises two protectors connected directly in parallel. One protector, for example a back-to-back semiconductor diode, has a breakdown voltage below which it is a high impedance. Between the breakdown voltage and a failure voltage it has a lower impedance. Above the failure voltage it has negligible impedance. The other protector, for example a gas tube, has a range of operating voltages which extends from below the breakdown voltage of the diode, to a voltage between the breakdown voltage and the failure voltage of the diode. In operation the two protectors interact, the diode operating, for example, on faster surges and, in so doing, slowing the surge front so as to increase the likelihood that the gas tube will fire.

Interactive overvoltage protection device

Telecommunications cable with a splice closure covering conductors which have been severed and each having one severed end electrically connected to another cable. The other severed ends of the conductors are placed in series with a coil formed of electrical windings to enable a current to be passed through the coil by passing it through the electrically 'dead' parts of the conductors to create an electromagnetic field around the coil to indicate the splice position. Preferably, the coil is formed by windings passing around the cable and these windings may be embedded in the closure.

Telecommunications cable splice closures

An overvoltage protection device, for protecting communications equipment against hazardous voltages cue to lightning or power surges, comprises a primary protector, for example a gas tube device, and a back-up protector connected in parallel. The back-up protector includes a semiconductor pn junction, and is preferably a pair of diodes back-to-back. The back-up protector has a breakdown voltage slightly higher than that of the primary protector and is arranged to fail short-circuit once it has operated so as to provide an indication that the primary protector failed to operate.

Overvoltage protection device

An overvoltage or surge protector, particularly for telephone lines, has two electrodes in opposition in a housing. The gap between the inner ends of the electrodes is set by a layer of dielectric material on the center portion of one or both end surfaces of the electrodes. Breakdown occurs with assistance from dielectric stimulation of the arc, resulting from an electrical field across the dielectric. The center portions are surrounded by annular grooves, which are also covered with a dielectric layer. The end surfaces external to the center portions can be convex, and also roughened.

Overvoltage protector for telephone lines

A method and apparatus for obtaining a distorted photographic reproduction from a negative photographic image, in which a sheet of photosensitive printing paper is attached to a planar surface of a table, the image negative is placed over the paper and a slitted mask is placed over the image negative. The image negative and the mask are moved laterally relative to one another and to the paper while the mask is exposed to a light source. To obtain a circular reproduction the mask is held stationary and the printing paper is rotated about an axis intersecting the slit while the image negative is moved laterally with respect to the slit.

Growing community of inventors

Almonte, Canada

James E Anderson