Blood pressure measuring apparatus

Claim 1

A blood pressure measuring apparatus comprising: a housing detachably set on a body surface of a subject; a cylindrical member accommodated in said housing; a pressure sensor secured to one of axial ends of said cylindrical member, said pressure sensor being opposed to said body surface when said housing is set on said body surface, said pressure sensor being pressed against said body surface so as to detect pulse wave produced from an arterial vessel of said subject, said pressure sensor generating a pulse wave signal representing the detected pulse wave; pressing means for pressing said pressure sensor against said body surface by moving said cylindrical member toward said body surface, said pressing means comprising (a) an externally threaded member secured to said housing and having an axis, said axis being substantially perpendicular to said body surface when said housing is set on said body surface, (b) an internally threaded member engaged with said externally threaded member and having a multiplicity of outer teeth formed in an outer circumference thereof, (c) a motor having an output shaft, and (d) a pinion secured to said output shaft of said motor and engaged with said outer teeth of said internally threaded member, the other axial end of said cylindrical member being fitted on said externally threaded member and engaged with said internally threaded member such that said cylindrical member is coaxial with said externally and internally threaded members, said pressing means further comprising (e) a means for guiding said cylindrical member along said axis of said externally threaded member without causing rotation of said cylindrical member about said axis, and (f) a means for permitting said internally threaded member to be rotated relative to said cylindrical member on said externally threaded member and thereby be moved together with said cylindrical member along said axis, whereby said pressure sensor secured to said cylindrical member is moved along said axis toward or away from said body surface without rotation of said pressure sensor about said axis when said motor is operated and consequently said internally threaded member is rotated on said externally threaded member and thereby is moved along said axis; control means for determining an optimum pressing force of said pressing means based on said pulse wave signal, and controlling said pressing means to press said pressure sensor against said body surface with said optimum pressing force, said controlling means determining a blood pressure in said arterial vessel based on the pulse wave signal supplied from said pressure sensor pressed with said optimum pressing force; and said pressing means and said control means being accommodated in said housing.