Optical interruption sensor with opposed light emitting diodes
First Claim
Patent Images
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.
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Abstract
An optical-interrupter provides a mechanically integrated electric light source and electric light sensor positioned across a gap to transmit a light beam across the gap that may be interrupted with an opaque vane. The optical-interrupter uses conventional LEDs for both the light source and a light receiver. An integrated circuit comparator may be used to provide an adjustable threshold for the determination of whether the light beam is blocked.
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Citations
19 Claims
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1. A photosensor-photodetector assembly comprising:
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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; andwherein 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 19)
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17. A photosensor-photodetector assembly comprising:
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a movable light opaque vane; a housing defining a light path through an open space from a first to a second position, the open space sized to permit movement of the vane into the open space in a first state and out of the open space in a second state; 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 light source and light detector fixed with respect to the housing at respective first and second positions so that light from the light source may be received by the light receiver across the open space in the first state and blocked from the light receiver in the second state; a biasing circuit providing an electrical bias to the light source and an electrical bias to the light detector, when a direct current supply voltage and ground voltage are received by the electrical terminals; detection circuitry including a threshold detector connected to the light source to compare a signal from the light detector 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; andwherein both the light source and light detector are light emitting diodes designed to emit light of a same frequency when biased for light emission, the light emitting diodes having direct band open space semiconductor materials forming a PN junction held within a case and supported on an opaque substrate, the case having a non-opaque portion permitting light to pass into and out of the housing; and wherein a substantially continuous electrical bias that is a substantially proportional function of the supply voltage is applied to the solid-state light source. - View Dependent Claims (18)
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Specification