Crystal oscillator compensated against frequency shift due to acceleration

Claim 2

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the resonator frequency which is connected in series with said resonator, said adjusting capacitance being formed of at least one variable capacitor; and means sensitive and responsive to acceleration imposed on said oscillator for controlling said variable capacitor whereby the frequency shift caused by said variable capacitor is opposed and substantially equal to the frequency shift of said resonator caused by the acceleration imposed on said oscillator.

Claim 3

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal and an adjusting capacitance for adjusting the frequency which is connected in series with said resonator; said adjusting capacitance being formed of at least one variable capacitor; said variable capacitor comprising a stationary electrode and a massive movable electrode having one degree of translational freedom whereby the movement of said electrode provides the variation in the capacitance of said variable capacitor; and a resilient return member operatively connected to said movable electrode, said return member being sensitive to acceleration imposed on said oscillator thereby controlling said variable capacitor so that the frequency shift caused by said variable capacitor is opposed and substantially equal to the frequency shift of said resonator caused by said acceleration.

Claim 4

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal and an adjusting capacitance for adjusting the frequency which is connected in series with said resonator; said adjusting capacitance being formed of at least one variable capacitor; said variable capacitor comprising a stationary electrode and a massive movable electrode having one degree of translational freedom whereby the movement of said electrode provides the variation in the capacitance of said variable capacitor; and a resilient return member operatively connected to said movable electrode, said return member being sensitive to acceleration imposed on said oscillator thereby controlling said variable capacitor so that the frequency shift caused by said variable capacitor is opposed and substantially equal to the frequency shift of said resonator caused by said acceleration.

Claim 5

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the resonator frequency which is connected in series with said resonator; said adjusting capacitance being formed of at least one variable capacitor; said variable capacitor comprising a stationary electrode and a massive movable electrode, the distance between the stationary and movable electrodes being variable; a resilient return member sensitive to acceleration imposed on said oscillator which consists of flexible blades fixed to said movable electrode; and means for maintaining said movable electrode parallelly to said stationary electrode whereby the frequency shift caused by the movement of said moveable electrode is opposed and substantially equal to the frequency shift of said resonator caused by said acceleration.

Claim 6

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the resonator frequency which is connected in series with said resonator; said adjusting capacitance being formed of at least one variable capacitor; said variable capacitor comprising a stationary electrode and a massive movable electrode, the distance between the stationary and movable electrodes being variable; a resilient return member sensitive to acceleration imposed on said oscillator which consists of flexible blades fixed to said movable electrode; and means for maintaining said movable electrode parallelly to said stationary electrode whereby the frequency shift caused by the movement of said moveable electrode is opposed and substantially equal to the frequency shift of said resonator caused by said acceleration.

Claim 7

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the frequency which is connected in series with said resonator; said adjusting capacitance being formed of at least one variable capacitor; said variable capacitor comprising a stationary plane electrode and a movable plane electrode having overlapping surfaces of said electrodes, the overlapping surfaces of said electrodes being variable; a resilient return member sensitive to acceleration imposed on said oscillator which consists of flexible blades fixed to said movable electrode; and means for maintaining said movable electrode at a constant distance from and parallel to said stationary electrode whereby variation of capacitance compensates for variation in frequency of said resonator caused by said acceleration.

Claim 8

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the frequency which is connected in series with said resonator; said adjusting capacitance being formed of at least one variable capacitor; said variable capacitor comprising a stationary plane electrode and a movable plane electrode having overlapping surfaces of said electrodes, the overlapping surfaces of said electrodes being variable; a resilient return member sensitive to acceleration imposed on said oscillator which consists of flexible blades fixed to said movable electrode; and means for maintaining said movable electrode at a constant distance from and parallel to said stationary electrode whereby variation of capacitance compensates for variation in frequency of said resonator caused by said acceleration.

Claim 9

An electrical oscillator as claimed in claim 4 wherein one of said electrodes of said variable capacitor has a rectangular surface and the other electrode has symmetrical profiled edges with respect to the middle plane of said rectangular electrode parallel to the direction of the translational movement, the profile of said profiled edges being expressed by the function of the displacement (u) of the electrode: P(u) = 1/(A(u-K).sup.2) where A is a constant dependent on the mechanical and geometric parameters of said return member and of said variable capacitor and K is a constant dependent on said geometric and mechanical parameters and also on said overlapping surface of said electrodes under zero acceleration of said oscillator.

Claim 10

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the frequency which is connected in series with said resonator; said adjusting capacitance being formed of at least one variable capacitor; said variable capacitor comprising a stationary electrode and a massive movable electrode having one degree of translational freedom for which the movement provides the variation in the capacitance of said variable capacitor; a resilient return member operatively connected to said movable electrode sensitive to acceleration imposed on said oscillator thereby controlling said variable capacitor so that the frequency shift caused by said variable capacitor is opposed and substantially equal to the frequency shift of said resonator caused by said acceleration; and said variable capacitor and said resilient return member being oriented such that said translational movement of said movable electrode is parallel to the vector of sensitivity to the acceleration of said piezoelectric crystal of said resonator.

Claim 11

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the frequency which is connected in series with said resonator; said adjusting capacitance being formed of at least one variable capacitor; said variable capacitor comprising a stationary electrode and a massive movable electrode having one degree of translational freedom for which the movement provides the variation in the capacitance of said variable capacitor; a resilient return member operatively connected to said movable electrode sensitive to acceleration imposed on said oscillator thereby controlling said variable capacitor so that the frequency shift caused by said variable capacitor is opposed and substantially equal to the frequency shift of said resonator caused by said acceleration; and said variable capacitor and said resilient return member being oriented such that said translational movement of said movable electrode is parallel to the vector of sensitivity to the acceleration of said piezoelectric crystal of said resonator.

Claim 12

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the frequency which is connected in series with said resonator; said adjusting capacitance being formed of three variable capacitors which are connected in parallel with each other and in series with said resonator; each of said variable capacitors comprising a stationary electrode and a massive movable electrode; and three means associated with respective ones of said three movable electrodes and each sensitive to acceleration imposed along a respective one of three crystal axes of said piezoelectric crystal for respectively controlling the movement of said movable electrodes so that the frequency shift caused by said variable capacitors is opposed and substantially equal to the frequency shift of said resonator caused by said acceleration.

Claim 13

In an oscillation sustaining loop of an electrical oscillator, that improvement comprising: a resonator having a piezoelectric crystal; an adjusting capacitance for adjusting the frequency which is connected in series with said resonator; said adjusting capacitance being formed of three variable capacitors which are connected in parallel with each other and in series with said resonator; each of said variable capacitors comprising a stationary electrode and a massive movable electrode; and three means associated with respective ones of said three movable electrodes and each sensitive to acceleration imposed along a respective one of three crystal axes of said piezoelectric crystal for respectively controlling the movement of said movable electrodes so that the frequency shift caused by said variable capacitors is opposed and substantially equal to the frequency shift of said resonator caused by said acceleration.