Patent ID: 11950885
Assignee: MITSUBISHI ELECTRIC CORPORATION
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 0:
1. A biosensor device comprising:
a signal generator to generate a continuous wave signal;
an antenna to emit the continuous wave signal as a radio wave;
a variable matching circuit to perform impedance matching between the signal generator and the antenna;
a detection circuit to output a detection signal on a basis of the continuous wave signal and a reflected signal of the radio wave, reflected by a human body, and incident on the antenna; and
control circuitry to control a capacitance value of a capacitance element in the variable matching circuit from the detection signal in a predetermined period corresponding to one cycle or more time in which heartbeat and respiration waveforms can be measured on a basis of the detection signal,, wherein the detection circuit includes:
a first mixer to multiply the continuous wave signal by the reflected signal;
a phase shifter to convert a phase of the continuous wave signal by 90 degrees; and
a second mixer to multiply output of the phase shifter by the reflected signal, and wherein the control circuitry stores, in advance, a complex number conversion coefficient having amplitude and phase information,
the detection signal includes an I signal output from the first mixer of the detection circuit and a Q signal output from the second mixer, and
when time average values of the respective two signals of I and Q in the detection signal in a predetermined period corresponding to one cycle or more time in which heartbeat and respiration waveforms can be measured are represented by VI and VQ, respectively, a heartbeat waveform signal Vr is represented by Vr=VI−jVQ, and
when a reflection coefficient of the variable matching circuit and the antenna is represented by Γm,
the conversion coefficient is calculated by Γm/Vr obtained by dividing the reflection coefficient Γm by the heartbeat waveform signal Vr.