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1. EP0941694 - Method for configuring a reflected light sensor

Note: Text based on automatic Optical Character Recognition processes. Please use the PDF version for legal matters
Claims

1. A method for configuring a reflected light sensor, said sensor being for irradiating light to a detection region of a living body by means of a light-emitting device and for detecting the intensity of reflected light of irradiated light of the light-emitting device, said reflected light being reflected from the detection region, the method comprising the steps of:

providing said light-emitting device for emitting said irradiated light

providing first and second photoelectric conversion devices (32, 33) for receiving light and for converting the received light into respective first and second output signals;

providing a difference-detection section (34, 35) for detecting a difference of the first and second output signals to output a difference signal, said difference signal being an indication of said intensity of reflected light; and

providing a belt-shaped fixing device (40) for preventing outside light from being directly incident on the light-emitting device (31) and on the first and second photoelectric conversion devices (32, 33) and for fixing the light-emitting device (31) and the first and second photoelectric conversion devices (32, 33) to the living body;

the method further comprising the steps of:

determining a distance (L2) from a light-reception center position of the second photoelectric conversion device (33) to a light-emission center position of the light-emitting device (31), whereby a sufficiently large absorption by the living body of the light from the light-emitting device (31) can take place, such that substantially no reflected light reaches the second photoelectric conversion device (33);

determining a distance (L1) from a light-reception center position of the first photoelectric conversion device (32) to a light-emission center position of the light-emitting device (31), whereby little absorption by the living body of the light from the light-emitting device (31) can take place, relative to the absorption associated with the second photoelectric conversion device (33), such that more reflected light reaches the first photoelectric conversion device (33) than reaches the second photoelectric conversion device (33); and

positioning the light-emitting device (31) and the first photoelectric conversion devices (32) and the light-emitting device (31) and the second photoelectric conversion device (33) at respective said distances (L1, L2) from each other, while also positioning the light-emitting device (31) and the first and second photoelectric conversion devices (32, 33) so that outside light, which passes on a skin surface of the living body, reaches both the first and second photoelectric conversion devices (32, 33) with substantially equal intensity.


  2. A method according to claim 1, wherein:

the difference-detection section (34, 35) generates a difference signal for detecting pulsation in blood flow, and

based on the difference signal, biological information indicative of a body condition is measured.


  3. A method according to claim 1, wherein the difference-detection section (34, 35) generates a difference signal for the measurement of a pulse.