Abstract An improved pulse transducer for providing an output signal which varies as a function of the pulse rate of a living body includes a plurality of light emitting diodes from which red light of a wavelength of from 6,000 to 9,000 angstroms is emitted. This red light is transmitted through the skin of a portion of the body to the blood in an artery. The wavelength of this light is such that it is not transmitted through the blood but is reflected to a sensor with an intensity which varies as a function of variations in pulse wave pressure in the artery. The light emitting diodes are relatively cool to minimize changes in the characteristics of the blood vessels during examination. In addition, the use of red light tends to maximize the amount of light reflected back to the sensor from the red blood and to minimize the amount of light reflected by the white skin to thereby minimize the signal-to-noise ratio in the output signal from the sensor.
A method of sensing variations in pulsatile blood in a living body without substantially heating the pulsatile blood or tissue of the living body, said method comprising the steps of providing a plurality of light sources capable of emitting red light of a wavelength between 6,000 and 9,000 angstroms at substantially ambient temperature, positioning the light sources adjacent to the outer surface of the skin of the living body, transmitting red light of a wavelength between 6,000 and 9,000 angstroms from the light sources through the skin of the living body toward a portion of the living body in which pulsatile blood is flowing without heating the living body, reflecting red light from the pulsatile blood of the living body, sensing the intensity of the light reflected from the pulsatile blood of the living body, and providing an output signal in accordance with the intensity of the sensed light.
Claim 2
Independent Claim
149 words
A method of sensing variations in pulsatile blood in a living body without substantially heating the pulsatile blood or tissue of the living body, said method comprising the steps of providing a plurality of light sources capable of emitting red light of a wavelength between 6,000 and 9,000 angstroms at substantially ambient temperature, positioning the light sources adjacent to the outer surface of the skin of the living body, transmitting red light of a wavelength between 6,000 and 9,000 angstroms from the light sources through the skin of the living body toward a portion of the living body in which pulsatile blood is flowing without heating the living body, reflecting red light from the pulsatile blood of the living body, sensing the intensity of the light reflected from the pulsatile blood of the living body, and providing an output signal in accordance with the intensity of the sensed light.
Claim 3
Dependent Claim
45 words
A method as set forth in claim 1 wherein said step of providing a plurality of light sources includes the step of providing a plurality of light emitting diodes and said step of transmitting red light includes the step of energizing the light emitting diodes.