MEMS scan controller with inherent frequency and method of control thereof

A Micro-Electronic-Mechanical-System (MEMS) scan controller with inherent frequency applied to a laser scanner unit formed by a laser source emitting laser light, a MEMS mirror that drives a reflection mirror by a resonant way to scan the laser light forward/reverse through the object, two photoelectric detectors (PD) that receives scanning light and turns the scanning light into PD signals, a scan lens that turns the scanning light into a linear relationship between angle and time and a laser controller that controls emitting of the laser source with preset frequency and time interval;

• wherein the MEMS scan controller comprising:
• a control logic, a control signal output unit and a bridge circuit;
• wherein the MEMS scan controller adjusts amplitude of the MEMS mirror by using the inherent resonant frequency of the MEMS mirror;
• the control logic receives PD signals from the two PDs, calculates time interval of the two PD signals to generate modulation signal of the MEMS mirror sent to the bridge circuit and amplitude variation signal of the MEMS mirror sent to the control signal output unit;
• the control signal output unit receives the amplitude variation signal from the control logic and turns the amplitude variation signal into stable signal that control the laser controller;
• the bridge circuit receives the modulation signal from the control logic and turns the modulation signal into driving signals that drive the MEMS mirror to oscillate;
• thereby the laser scanner sends scan data string with preset frequency and time interval within effective scan window.

A control method for MEMS scan controllers with inherent frequency applied to a MEMS scan controller with one PD comprising the steps of:

• S1:
• checking whether a laser controller sends enable (ENB) signals or not;
• once the laser controller sends the ENB signal, a MEMS scan controller is turned on and a control logic of the MEMS scan controller sends modulation signals for driving a bridge circuit to make a MEMS mirror start oscillation;
• the control logic also calculates scan frequency and scan amplitude;
• S2:
• sending modulation signals by the control logic of the MEMS scan controller so as to make the MEMS mirror oscillate stably with preset amplitude;
• S3:
• sending stable signals to the laser controller by a control signal output unit of the MEMS scan controller after the MEMS mirror becoming stable.