Patent ID: 9476897
Filing Date: 2016-10-25
CPC Classification: G01C,G01P

Claim Text:
1. An oscillatory type angular velocity sensor applying a physical quantity sensor to angular velocity detection, the physical quantity sensor including: a substrate; a drive weight supported by the substrate via a first spring; a detection weight supported by the drive weight via a second spring, the detection weight including a detection movable electrode; and a detection fixed portion including a detection fixed electrode that is arranged to be opposed to the detection movable electrode, wherein: an application of a physical quantity, while the drive weight is driven and vibrated, displaces the detection movable electrode and the detection weight to change an interval between the detection movable electrode and the detection fixed electrode; the physical quantity is detected based on the changed interval; f1 is defined as a resonance frequency in same-phase mode where the drive weight moves following the application of the physical quantity in a direction identical to a direction in which the detection weight moves; f3 is defined as a resonance frequency in same-phase absorptive mode where the drive weight moves following the application of the physical quantity in a direction opposite to a direction in which the detection weight moves; n is defined as an integer that is equal to or greater than one; the resonance frequency f3 in the same-phase absorptive mode is greater than the resonance frequency f1 in the same-phase mode; Δf3, which is expressed by Δf3=|f3−n·f1|, is defined as an absolute value that is a difference between the resonance frequency f3 in the same-phase absorptive mode and a value that is a product of the resonance frequency f1 in the same-phase mode multiplied by n; D, which is expressed by D=Δf3/(n·f1)=|f3−n·f1|/(n·f1), is defined as an avoidance difference that indicates a degree of deviation of the absolute value Δf3 from the resonance frequency f1 in the same-phase mode; and a relation, which is expressed by Δf3>n·f1·D, is satisfied and, simultaneously, the avoidance difference D is provided to be greater than 0.00, the drive weight of the physical quantity sensor being provided as a pair of inner drive weights, the inner drive weights surrounding the detection weight, the inner drive weights being connected to the detection weight via detection beams corresponding to the second spring, the oscillatory type angular velocity sensor comprising: a pair of outer drive weights located at both outer sides that sandwich the pair of inner drive weights; and a drive fixed portion to generate electrostatic attraction that vibrates the inner drive weights and the outer drive weights in mutually opposite directions, wherein the inner drive weights are connected to the outer drive weights by drive beams while the outer drive weights and the inner drive weights connected to the detection weight are supported to the substrate by support members that include the first spring, wherein: the drive beams are bent based on the electrostatic attraction generated by the drive fixed portion to perform a sensor drive that vibrates the outer drive weights and the inner drive weights; when an angular velocity is applied as the physical quantity during the sensor drive being performed, the detection beams are bent so that the detection weight is moved in a direction orthogonal to an oscillating direction of the inner drive weights to change a capacitance between the detection fixed electrode and the detection movable electrode; and the angular velocity is detected base on the changed capacitance.