Abstract
A mechanical trigger inertial micro-switch with spring stationary electrode is proposed and fabricated by surface micromachining. The elastic contact process and stability performance are evaluated through experimental tests performed using a drop hammer. The test results show that the contact time is about 110 μs and 100 μs when the threshold acceleration is 480 g and the overload acceleration is 602 g, respectively. The vibration process of the electrodes is explained through an established physical mode. The elastic contact process is analyzed and discussed by Finite Element Analysis (FEA) simulations, which indicated that the contact time is about 65 μs when the threshold acceleration is 600 g. At the same time, this result also proved that the contact time could be extended effectively by the designed spring stationary electrode. The overload acceleration (800 g) has been applied to the Finite-Element model in ANSYS, the contact process indicated that the proof mass contacted with stationary electrode three times, and there was no bounce phenomenon during contact process, which fully proved that the stable contact process can be realized at high acceleration owing to the designed elastic stationary electrode.
Highlights
Inertial micro-switches are threshold accelerometers which can be used to realize the on-off state of a signal electrode when the moving electrode contacts the stationary electrode
It is required that the frequency of the trigger signal be small enough to distinguish the trigger signal from the noise signal, so as to avoid system misjudgments
The dynamicinertial contactmicro-switch process indicates that simulation results the threshold acceleration of designed is about the contact time can be prolonged owing to the elastic deformation of the stationary electrode spring
Summary
Inertial micro-switches are threshold accelerometers which can be used to realize the on-off state of a signal electrode when the moving electrode contacts the stationary electrode. The trigger signal of an inertia switch needs to be collected and processed by a pre-circuit before entering the drivers. It is required that the frequency of the trigger signal be small (large pulse width) enough to distinguish the trigger signal from the noise signal, so as to avoid system misjudgments. A stable and low-frequency trigger signal is conducive to signal processing by the pre-circuit. When the comparator in the pre-circuit is used to capture the trigger signal and output a signal with equal pulse width, unstable signals can cause the signal to be ignored, and cause system misjudgments. To achievestable stableand and frequency trigger signals, two inertial structure design. To achieve lowlow frequency trigger signals, two inertial switch switch structure design schemes schemes are proposed.
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