Abstract: A semiconductor magnetic field sensor has a base region, an emitter which injects minority carriers into the base region along an injection axis, and a collector intersected by the injection axis which collects minority carrier flows. An additional pair of collectors are laterally spaced from the emitter and the injection axis to receive lateral current components arising in the base region from the injected minority carriers. Magnetic fields applied to the base cause a redistribution of the minority carriers between the lateral current components and the strength of the magnetic field can be measured by comparing the magnitudes of the resulting collector currents. Base strips on laterally opposing sides of the emitter form junctions that suppress parasitic lateral injection. Reverse biasing the junctions focuses the injected minority carriers to a greater degree along the injection axis thereby markedly enhancing device sensitivity.

Abstract: A security blank includes a sheet, and an elongated security thread connected to the sheet. The security thread may be identified upon being irradiated by electromagnetic radiation by a recognizable signature from radiation scattered therefrom; the cross-section of the security thread is other than circular or rectangular and is substantially constant over a prearranged portion of the length thereof.

Abstract: A magnetic field sensor having a lateral bipolar magnetotransistor incorporating only a single emitter region and whose base region is incorporated as a well in the surface of a silicon substrate of the reverse material conduction type. The P/N junction of the base region with the silicon substrate is reverse biased by means of at least one secondary collector contact. The emitter region must be kept as shallow than 0.5 .mu.m or be so lowly doped with impurity atoms that its resistivity is greater than 100 ohms per square or both. The sensitivity of the magnetic field sensor is approximately 100%/Tesla.

Abstract: A magnetic field sensor having two component layer transistors of opposite polarities are cross connected together and give a higher degree of sensitivity, by virtue of that feedback effect. The magnetic field sensor serves for measuring a magnetic field and is supplied by way of a costant current source from a d.c. voltage supply. In an alternative embodiment, it has a working point adjusting circuit, a change-over contact circuit, and a voltage regulator for nullifying the offset voltage.

Abstract: The magnetic field sensor is composed of a semiconductor magnetic field sensor, for example a magnetotransistor, and at least one NiFe or NiCo film disposed upon its surface. This film functions as a zero-crossing switch utilizing its magnetic induction/magnetic field-reversal hysteresis properties. The film is deposited immediately above the field sensitive zone of the magnetic field sensor with its easy axis oriented perpendicularly to the direction of current flow of the sensor. The semiconductor magnetic field sensor detects the magnetic induction generated by the film.

Abstract: A security blank is formed with a light-redirecting spatial structure including a deterministic component establishing at least one authenticating feature, and a stochastic component superimposed on the deterministic component, and sufficiently obscuring the deterministic component so as largely to frustrate recognition of the function of the authenticating feature by intensity measurement of light reflected therefrom. Recognition of the function of the authenticating feature is made possible by a method and an apparatus measuring the degree of coherence of two narrow bundles of light rays obtained from light reflected from the spatial structure upon its illumination by light of a selected wavelength.

Abstract: A cell which is arranged to allow the transfer of charges between two electrodes, includes two electrically conducting electrodes spaced apart from one another, and a solid dielectric material disposed between the electrodes, and including a certain quantity of carriers of a positive charge trapped therein.