Infrared proximity detecting apparatus
First Claim
1. Proximity detection apparatus comprising:
- means for generating pulses of infrared radiation at a predetermined frequency along a preselected direction;
infrared detector means positioned with respect to said generating means for producing an analog signal responsive to the detection of infrared radiation;
synchronous monitoring means for receiving said analog signal and generating a first digital signal representative of infrared radiation detected in synchronization with generated infrared radiation, said monitoring means including missing pulse detection means for monitoring said first digital signal with respect to a first predetermined time period for generating a second digital signal representative of the frequency synchronization of detected infrared radiation and generated infrared radiation; and
timer means for receiving said second digital signal and producing a third digital signal representative of said frequency synchronization occurring for at least a second predetermined time period.
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Abstract
A proximity detecting apparatus for generating a beam of infrared light rays in the form of successive radiation pulses occuring at a predetermined frequency for reflection off objects moving within the proximity of the apparatus. A photo-detector device positioned adjacent to the radiation beam senses the reflected rays and responsively produces an output signal. Other light radiation and electrical signal noise sensed by the detector are filtered from the output signal according to the pulse width and frequency of pulse radiation generated by the beam. A detected signal is established as valid only if the signal and the infrared source are in frequency synchronization and if an unbroken pulse train is detected for a predetermined length of time.
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Citations
11 Claims
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1. Proximity detection apparatus comprising:
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means for generating pulses of infrared radiation at a predetermined frequency along a preselected direction; infrared detector means positioned with respect to said generating means for producing an analog signal responsive to the detection of infrared radiation; synchronous monitoring means for receiving said analog signal and generating a first digital signal representative of infrared radiation detected in synchronization with generated infrared radiation, said monitoring means including missing pulse detection means for monitoring said first digital signal with respect to a first predetermined time period for generating a second digital signal representative of the frequency synchronization of detected infrared radiation and generated infrared radiation; and timer means for receiving said second digital signal and producing a third digital signal representative of said frequency synchronization occurring for at least a second predetermined time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. Proximity detection apparatus comprising:
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means for generating pulses of infrared radiation at a predetermined frequency along a preselected direction; infrared detector means positioned with respect to said generating means for producing an analog signal responsive to the detection of infrared radiation; synchronous monitoring means for receiving said analog signal and generating a first digital signal having a first binary state solely when infrared radiation is detected in synchronization with generated infrared radiation, said monitoring means including circuit means for monitoring said first digital signal with respect to a first predetermined time period and generating a second digital signal representative of the frequency synchronization of detected infrared radiation and generated infrared radiation; and timer means for receiving said second digital signal and producing a third digital signal representative of said frequency synchronization occurring for at least a second predetermined time period.
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Specification