Abstract: A mirror heating system includes a sheet heater, sized and adapted to cover most of the back of the mirror surface, that can be mounted on the wall or other flat surface before the mirror is put into place. The system is designed so that, despite the needed electrical connections, the front and rear surfaces of the heating system remain essentially planar and parallel.

Abstract: A truck trailer or similar bulk storage area is heated by providing electrical resistance heaters in longitudinally-extending metal ducts extending from and to a short distance below the floor level. Electrical sheet resistance heaters are attached to the underside of the metal plate forming the duct top, each duct is placed between a longitudinally-extending pair of wooden floor boards, and a pair of ducts are placed side-by-side near each edge of the trailer bed or floor of the storage area.

Abstract: An electrical resistance device includes a conductive metal pattern carried on an insulating surface. A portion of the conductive metal pattern includes a two-dimensional array of areas devoid of conductive material ("voids") within a mesh of conductive material. Typically, the voids are hexagonal and are arranged such that the adjacent edges of adjacent hexagons are parallel to each other and spaced apart a distance not more than about 0.10 in. The hexagonal voids typically are arranged so that the centers of sets of three adjacent voids lie on the corners of equilateral triangles.

Abstract: Heating devices, in which a semi-conductor pattern is carried on an insulating surface and a pair of spaced apart electrodes are electrically connected to the semi-conductor pattern, are characterized in that the semi-conductor pattern in at least one heating area of the device defines a two-dimensional array of areas that are devoid of semi-conductor material ("voids") within a continuous "mesh" of semi-conductive material. Preferably, the voids are hexagons arranged with the sides of adjacent hexagons parallel to each other, the centers of adjacent hexagons are at the corners of equilateral triangles, and the overall direction of current flow in the device is not parallel to any of the sides of the triangles.

Abstract: An electrical resistance device includes a conductive metal pattern carried on an insulating surface. A portion of the conductive metal pattern includes a two-dimensional array of areas devoid of conductive material ("voids") within a mesh of conductive material. Typically, the voids are hexagonal and are arranged such that the adjacent edges of adjacent hexagons are parallel to each other and spaced apart a distance not more than about 0.10 in. The hexagonal voids typically are arranged so that the centers of sets of three adjacent voids lie on the corners of equilateral triangles.

Abstract: A flat, multi-cable assembly is provided by laminating a multiplicity of flat tinned-copper strip conductors between a pair of organic plastic insulating sheets, both of which adhere tightly to each other but at least one of which is not adhered to the copper strip conductors. The copper strip conductors are typically parallel to and spaced-apart (not less than about 1/8 inch) from each other, and the distance between adjacent conductors is typically about equal to (or a major fraction of) the width of the conductors. One of the conductors includes a plurality of electrically isolated portions each of which is electrically connected to a respective one of the other conductors. The latter connections are provided by a plurality of conductor connecting patterns carried on one of the plastic insulating sheets (typically printed thereon using a conductive graphite, nickel or silver ink).