Blood pressure meter and pump driving system

A blood pressure meter, comprising:

• a piezoelectric pump configured to send a fluid to a blood pressure measurement cuff;
• a pump driving circuit for driving the piezoelectric pump;
• and
• a processor configured to control the pump driving circuit in order to measure blood pressure, wherein
• the pump driving circuit includes:
• a step-up unit that steps up a first DC voltage from a power supply and outputs it as a second DC voltage according to a step-up control signal from the processor, and
• an H bridge unit including first and second series circuits that each include two switching elements that are connected in series between a high potential corresponding to the second DC voltage and a reference potential that is lower than the high potential,
• the two switching elements of the first series circuit are switched on and off in a complementary manner according to bridge control signals from the processor, and the two switching elements of the second series circuit are switched on and off in a complementary manner with a phase that is an inverse of that of the switching on and off of the two switching elements of the first series circuit,
• a voltage that is generated between a first contact point between the two switching elements of the first series circuit and a second contact point between the two switching elements of the second series circuit is used as a driving voltage for driving the piezoelectric pump, and
• the processor is configured to cause the switching elements of the first and second series circuits to transition from an off state to an on state and from the on state to the off state over finite transition periods.

A pump driving system, comprising:

• a piezoelectric pump;
• a pump driving circuit for driving the piezoelectric pump;
• and
• a processor configured to control the pump driving circuit, wherein
• the pump driving circuit includes:
• a step-up unit that steps up a first DC voltage from a power supply and outputs it as a second DC voltage according to a step-up control signal from the processor, and
• an H bridge unit including first and second series circuits that each include two switching elements that are connected in series between a high potential corresponding to the second DC voltage and a reference potential that is lower than the high potential,
• the step-up control signal from the processor is a pulse width modulation signal,
• the step-up unit is a step-up regulator that includes a first resistance unit that includes a resistor and a FET and varies the resistance value according to the pulse width of the pulse width modulation signal, and a second resistance unit, and can vary and output the second DC voltage by dividing the second DC voltage between the first resistance unit and the second resistance unit and causing it to be fed back,
• the two switching elements of the first series circuit are switched on and off in a complementary manner according to bridge control signals from the processor, and the two switching elements of the second series circuit are switched on and off in a complementary manner with a phase that is an inverse of that of the switching on and off of the two switching elements of the first series circuit,
• a voltage that is generated between a first contact point between the two switching elements of the first series circuit and a second contact point between the two switching elements of the second series circuit is used as a driving voltage for driving the piezoelectric pump, and
• the processor configured to set a rest period in which all switching elements are off between an on period of a switching element in each of the first and second series circuits and an on period of another switching element that follows the on period.