Hall effect contactless switch with prebiased schmitt trigger

Claim 1

A monolithic integrated circuit contactless switch element comprising: a. a body of silicon semiconductor material of P-type conductivity having a generally N-type surface region of epitaxial silicon of about 0.3 mil thickness, said N-type surface region having an impurity concentration of less than about 2 X 1016 atoms per cc., said epitaxial silicon having extending therethrough P-type regions in a pattern to provide a multiple number of N-type zones electrically isolated from one another by at least two PN junctions, b. a first of said N-type zones defining a all element with first and second ohmic electrodes spaced at remote points thereof and arranged to pass an electric current along a first axis of said Hall element, c. first and second Hall probe electrodes asymmetrically located along the second axis of said Hall element, said first Hall probe being located nearer said first ohmic electrode, d. second and third of said N-type zones including therein respectively first and second NPN transistors of closely matching VBE. e. a fourth of said N-type zones having a generally elongated configuration defining a first resistor with remotely located electrodes thereon, f. a fifth of said N-type zones having a generally elongated configuration defining a second resistor with remotely located electrodes thereon, g. lead means adapted to supply positive voltages to said first ohmic electrode and to a first electrode of said second resistor and a negative voltage to the second of said ohmic electrodes and to a first electrode of said first resistor, h. the first Hall probe electrically connected to the base of said second transistor and to the collector of said first transistor, i. the second Hall probe electrically connected to the base of said first transistor, j. the emitters of said transistors being electrically connected to a second electrode of said first resistor, k. the collector of said second transistor being electrically connected to a second electrode of said second resistor, and also connected to an output electrode, l. the ratio of said first resistor to the resistance of the collector of said first transistor through said Hall element to the voltage source being of a value to provide a latching mode operation of said switch upon activation and deactivation by a magnetic source.