Patent ID: 7510530

Claim:
A pulse wave measuring apparatus comprising: a pressure sensor that is configured to be pressed above an artery of a subject body; a pressing device configured for applying pressure to the pressure sensor; a pulse wave measuring unit configured for measuring pulse wave generated from the artery based on pressure information output from the pressure sensor in a process of changing the level of the pressure applied by the pressing device to the pressure sensor, the pressing device including: a gas container of a constant capacity for adjusting the level of the pressure applied to the pressure sensor using pressure of gas in the gas container, and a state changing unit setting the pressure of the gas container to a gas holding state for holding an amount of the gas, changing the gas holding state to a gas isolating state for isolating a partial amount of the gas held in the gas container in the gas holding state from the remaining amount of the gas, changing the gas isolating state to a gas discharging state for discharging the partial amount of the gas in the gas container that is isolated in the gas isolating state, and changing the gas discharging state to the gas holding state for holding the remaining amount of the gas in the gas container; an isolation unit keeping the partial amount of the isolated gas; a main unit; a gas flow adjustment unit adjusting a gas flow passage between the main unit and the isolation unit, wherein a pressure adjusting unit further includes a supply source for supplying gas to the gas container in a gas supplying state; wherein the state changing unit is configured for setting the pressure adjusting unit to the gas supplying state for supplying gas to the gas container; wherein the state changing unit controls the three-port valve for connecting a main-unit-related port to the isolation-unit-related port in establishing the flow passage, and controls the three-port valve for connecting the main-unit-related port to a supply-related port in shutting off the flow passage and in the gas supplying state; and wherein the gas flow adjustment unit is a three-port valve having a main-unit-related port for input/output of gas from/to the main unit, an isolation-unit-related port for input/output of gas from/to the isolation unit and a supply-related port for input of gas from the supply source.