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Pulse detector with unworn-state detection

  • US 9,402,551 B2
  • Filed: 02/09/2012
  • Issued: 08/02/2016
  • Est. Priority Date: 02/23/2011
  • Status: Active Grant
First Claim
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1. A pulse detector that detects a pulse signal originating from a pulse of a subject and an unworn state of the pulse detector, the unworn state being a state in which the pulse detector has been removed from the subject, the pulse detector comprising:

  • a pulse wave sensor outputting a pulse wave signal that includes the pulse signal;

    an amplifier amplifying the pulse signal;

    a pulse wave sensor sensitivity adjustment section that adjusts a sensitivity of the pulse wave sensor based on an input signal to the pulse wave sensor or an intensity of the pulse wave signal, the sensitivity being a gain of the amplifier;

    a body movement sensor that detects body movement of the subject and outputs a body movement sensor signal originating from the body movement;

    an unworn-state detector that detects, at predetermined time intervals, an unworn state;

    wherein to detect the unworn state at a current timing, which is subsequent to a previous timing with one of the predetermined time intervals between the previous timing and current timing, the unworn state detector;

    obtains the sensitivity,determines whether or not the unworn state has been detected at the previous timing,wherein in response to determining that the unworn-state detector has detected the unworn state at the previous timing, setting a first level as a sensitivity threshold,wherein in response to determining that the unworn-state detector has not detected the unworn state at the previous timing, setting a second level, which is greater than the first level, as the sensitivity threshold; and

    wherein the unworn-state detector detects the unworn state at the current timing in response to determining that the sensitivity is greater than the sensitivity threshold, and determining that a level of the body movement sensor signal outputted from the body movement sensor is less than a predetermined movement threshold value.

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