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Elevator system

  • US 4,503,939 A
  • Filed: 08/19/1983
  • Issued: 03/12/1985
  • Est. Priority Date: 08/19/1983
  • Status: Expired due to Term
First Claim
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1. A speed switch for determining the speed of an elevator car relative to a predetermined speed V, comprising:

  • an oscillator having a predetermined fixed frequency F,a first counter disposed to provide a first count responsive to F,a latch for latching the first count in reponse to a latch signal L,a memory,means for addressing said memory with the latched first count,said memory being programmed to output a first signal when addressed by a count value which is below a predetermined value C, and to otherwise output a second signal,means providing distance pulses at a rate of P pulses per inch of movement of the elevator car,a second counter disposed to provide a second count responsive to said distance pulses,reference means for providing a reference count R which is a function of V, P and the time T for the first counter to count to C,comparator means for providing a latch signal L for said latch each time the second count and the reference count R have a predetermined relationship,and reset means responsive to each latch signal L for resetting said first and second counters,whereby said memory outputs the second signal when the second count reaches the predetermined relationship with the count R in the time T or more, indicating the car speed is V or less, and the first signal in a time less than T, indicating the car speed is greater than V.

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