ANGULAR VELOCITY SENSOR AND MANUFACTURING METHOD THEREFOR

摘要

One or more vibration plate layers of a diaphragm part are formed by a thin film forming technique. When a resonance frequency in a resonance vibration mode calculated from dimensions of a structure of an angular velocity sensor and an elastic parameter of a material thereof is defined as f kilohertz, a mass of a weight part is defined as M milligrams, a circumference of the diaphragm part is defined as r meters, a stress applied to a piezoelectric layer is defined as σp pascals, a thickness thereof is defined as tp meters, a stress applied to an n-th layer from the weight part in a vibration plate portion constituted by a plurality of layers including a lower electrode and the vibration plate layers is defined as τn pascals, and a thickness thereof is defined as tn meters (where n is a natural number), Teff expressed by Teff=r(σptp+Σσntn)/M satisfies {(−0.36f2+210)/33}≦Teff≦{(0.44f2+210)/33}.

主权项

1. An angular velocity sensor comprising:
a flexible diaphragm part including a laminated structure, the laminated structure of the diaphragm part including an upper electrode, a piezoelectric layer, a lower electrode, and one or more vibration plate layers, the upper electrode including a driving electrode part and a detection electrode part, the driving electrode part and the detection electrode part being pattern-arranged; a pedestal section configured to support an outer circumference of the diaphragm part; and a weight section joined to a central part of the diaphragm part, the angular velocity sensor being configured to cause the weight section to vibrate using an inverse piezoelectric effect of a piezoelectric body by applying an electric field to the piezoelectric layer via the driving electrode part, and detect a displacement generated in the weight section based on a Coriolis force, the displacement being detected by a piezoelectric effect from the detection electrode part, the vibration plate layer being formed by a thin film forming technique, and when a resonance frequency in a resonance vibration mode calculated from dimensions of a structural body of the angular velocity sensor and an elastic parameter of a material of the structural body is f kilohertz, a mass of the weight section is M milligrams, a circumferential length of the diaphragm part is r meters, a stress acting on the piezoelectric layer is σP pascals, a film thickness of the piezoelectric layer is tP meters, a stress acting on an n-th layer of a vibration plate portion constituted by a plurality of layers including the lower electrode and the one or more vibration plate layers is σn pascals, the n-th layer being n-th from a side of the weight section, and a film thickness of the n-th layer being tn meters, and when n is a natural number, then, Teff expressed by an expression:Teff=r(σptp+∑nσntn)M[Math1]satisfies:-0.36f2+21033≤Teff≤0.44f2+21033.[Math2]