Heartbeat detection method and heartbeat detection device

A heartbeat detection device comprising:

• an electrocardiograph having electrodes attached on a surface of a living body, and configured to output a sampling data string obtained by sampling at a predetermined time interval an electrocardiographic waveform of the living body;
• a storage device configured to store the sampling data string output by the electrocardiograph;
• a first FIFO (First-In, First-Out) buffer memory configured to store a first value input for a first delay time L1 before outputting the first value;
• a second FIFO buffer memory configured to store a second value input for a second delay time L2 before outputting the second value;
• a third FIFO buffer memory configured to receive the second value output from the second FIFO buffer memory as a third value input and store the third value for a third delay time L3 before outputting the third value;
• a fourth FIFO buffer memory configured to receive an output from the third FIFO buffer memory as a fourth value input and store the fourth value for a fourth delay time L4 before outputting the fourth value;
• and
• a processing circuit, wherein the processing circuit comprises:
• a time difference value calculation circuit configured to read out the sampling data string, calculate, for each sampling time, a time difference value between consecutive sampling data of the sampling data string, and sequentially input the time difference value to both of the first FIFO buffer memory and the second FIFO buffer memory;
• a minimum value detection circuit configured to detect, for each sampling time, a minimum value M out of a plurality of time difference values stored in the second FIFO buffer memory and the fourth FIFO buffer memory;
• and
• a heartbeat time determination circuit configured to calculate, for each sampling time, a difference value M−a between the minimum value M detected by the minimum value detection circuit and an output value a of the first FIFO buffer memory, compare the difference value M−a to a threshold, and determine, when the difference value M−a is equal to or greater than the threshold, the sampling time associated with the output value a as a heartbeat time,
• wherein each of the first delay time L1, the second delay time L2, the third delay time L3 and the fourth delay time L4 is an integer multiple of the predetermined time interval to produce the sampling data string of the electrocardiographic waveform.