Pulse transit time measurement device and blood pressure measurement device

A pulse transit time measurement device comprising:

• a belt unit configured to be wound around a target measurement site of a user;
• a plurality of first electrodes provided on an inner circumferential surface of the belt unit;
• a second electrode provided on the inner circumferential surface of the belt unit;
• a third electrode provided on an outer circumferential surface of the belt unit;
• a first electrocardiographic signal measurement circuit configured to measure a first electrocardiographic signal of the user based on a potential difference between two first electrodes selected from the plurality of first electrodes;
• a second electrocardiographic signal measurement circuit configured to measure a second electrocardiographic signal of the user based on a potential difference between the second electrode and the third electrode;
• a pulse wave signal acquisition circuit including a pulse wave sensor provided in the belt unit and configured to acquire a pulse wave signal representing a pulse wave of the user using the pulse wave sensor;
• and
• a processor coupled to the first electrocardiographic signal measurement circuit and the second electrocardiographic signal measurement circuit, the processor being configured to:
• simultaneously receive the first and second electrocardiographic signals measured respectively by the first and second electrocardiographic signal measurement circuits;
• detect a waveform feature point of the second electrocardiographic signal in a predetermined time period;
• determine a time range including a time of the waveform feature point of the second electrocardiographic signal, the time of the waveform feature point of the second electrocardiographic signal being at a center of the time range;
• detect a waveform feature point of the first electrocardiographic signal in the time range;
• calculate a feature amount parameter based upon the waveform feature point of the first electrocardiographic signal;
• and
• calculate a pulse transit time based on a time difference between the detected waveform feature point of the first electrocardiographic signal and a waveform feature point of the pulse wave signal.