Patent ID: 8981280
Filing Date: 2015-03-17
Classification: G01D,G01J,H01L

Abstract:
1. A photosensor-photodetector assembly comprising: a support defining an unobstructed light path through a gap from a first to a second position; electrical terminals adapted to receive a direct current supply voltage and ground voltage for the photosensor-photodetector assembly and to provide an electrical output from the photosensor-photodetector assembly; a solid-state light transmitter and solid-state light receiver attached to the support in the first and second positions so that light from the solid-state light transmitter may be received by the solid-state light receiver, the gap sized to permit an optical blocking element to pass into and out of the gap to block the light from the solid-state light transmitter to the solid-state light receiver; a biasing circuit providing an electrical bias to the solid-state light transmitter and an electrical bias to the solid-state light receiver, when a direct current supply voltage and ground voltage are received by the electrical terminals; detection circuitry including a threshold detector connected to the solid-state light receiver to compare a signal from the solid-state light receiver to a threshold signal to provide the electrical output; wherein the threshold signal varies with the supply voltage to compensate for changes in the illumination of the solid-state light transmitter with changes in supply voltage; and wherein the solid-state light transmitter and solid-state light receiver are both light emitting diodes; and wherein a substantially continuous electrical bias that is a substantially proportional function of the supply voltage is applied to the solid-state light transmitter.