Abstract: An icing detector is disclosed for detecting presence of ice in static air. An exemplary detector includes an ice collecting surface; a light emitter for emitting a light beam crossing an ice collecting surface, having a prismatic light manipulating window for internally-reflecting the light beam when no ice is present on the ice collecting surfaces, and externally-refracting the light when clear ice is present on the ice collecting surface, wherein the ice collecting surface is oriented to cause standing water to be directed away from the prismatic light manipulating window by gravity; a light sensor in a path of the reflected light; and an annunciator coupled to the light sensor for annunciating the presence of ice when light is sensed by the light sensor.

Abstract: An icing detector is disclosed for detecting presence of ice in static air. An exemplary detector includes an ice collecting surface; a light emitter for emitting a light beam crossing an ice collecting surface, having a prismatic light manipulating window for internally-reflecting the light beam when no ice is present on the ice collecting surfaces, and externally-refracting the light when clear ice is present on the ice collecting surface, wherein the ice collecting surface is oriented to cause standing water to be directed away from the prismatic light manipulating window by gravity; a light sensor in a path of the reflected light; and an annunciator coupled to the light sensor for annunciating the presence of ice when light is sensed by the light sensor.

Abstract: According to the invention, there is provided an icing detector for detecting presence of both rime ice and clear ice in air comprising an ice collecting surface facing an oncoming air stream; light emitting apparatus for emitting a light beam crossing the ice collecting surface, having a prismatic light refracting window for refracting the light beam in a first direction, when no ice is present on the ice collecting surface; light sensing apparatus in a path of the second direction, and annunciating apparatus coupled to the light sensing apparatus for annunciating presence of ice when light is sensed by the light sensing apparatus.

Abstract: A touch-responsive circuit uses an ohmic contact connected via a dc blocking capacitor to the high impedance input of an amplifier. A controllable impedance element shunts the capacitor and amplifier input. When the element is in the high impedance state, a weak voltage induced by touching the ohmic contact causes the amplifier to produce an output signal indicative of such touching. Touch response is disabled when the element is in the low impedance state. Advantageously, the controllable impedance element comprises a series-connected pair of diodes that are selectively forward or reverse biased; the element also may comprise an active electronic device such as a transistor.A data input terminal employs a matrix of ohmic contacts each having an associated touch-responsive circuit. Column scanning is accomplished by conditioning the controllable impedance elements in all but a selected one column to the low impedance state so that touch response is enabled only in that one selected column.