MEMS scanning mirror and laser projector
A scanning mirror and mirror technology, applied in the field of laser projection, can solve the problems of reduced detection accuracy, impacted actuator accuracy, increased noise, etc.
Active Publication Date: 2021-05-18
GOERTEK INC
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Problems solved by technology
[0006]
In the case of using an external piezoelectric actuator forming a curved cantilever such as
figure 1
In the shown two-dimensional MEMS scanning mirror structure, when using an angle sensor such as a piezoelectric effect to sense the deflection angle of the mirror 10 rotating around the X-axis and / or Y-axis, the signal-to-noise ratio (SNR) of the output signal of the angle sensor Lower, it will cause the reduction of detection accuracy, thus affecting the accuracy of actuator control
For MEMS scanning mirrors of various structures, one of the main reasons for the low signal-to-noise ratio of the output signal of the angle sensor is that the angle sensor of the piezoelectric effect is a variable capacitance element, and the thermal noise is caused by the resistance of the readout circuit connected to it. value, while conventional voltage reading methods usually use high-resistance components, so the noise in the low frequency range increases
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[0024] In order to illustrate the present invention more clearly, the present invention will be further described below in conjunction with preferred embodiments and accompanying drawings. Similar parts in the figures are denoted by the same reference numerals. Those skilled in the art should understand that the content specifically described below is illustrative rather than restrictive, and should not limit the protection scope of the present invention.
[0025] One embodiment of the present invention provides a MEMS scanning mirror, including a mirror, an angle sensor, a control unit, and an actuator used as a cantilever, and the actuator is used to make the mirror Rotate around the first rotation axis, the angle sensor is used to sense the deflection angle of the mirror around the first rotation axis and output a signal to the control unit, the control unit includes a driver and a charge readout circuit, so The charge readout circuit is used to output a constant voltage s...
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The invention discloses an MEMS scanning mirror and a laser projector. According to one specific embodiment, the MEMS scanning mirror comprises a reflecting mirror, an angle sensor, a control unit and an actuator used as a cantilever. The actuator is used for enabling the reflecting mirror to rotate around a first rotating shaft according to the control of the control unit. The angle sensor is used for sensing the deflection angle of the reflecting mirror rotating around the first rotating shaft and outputting a signal to the control unit, the control unit comprises a driver and a charge reading circuit, and the charge reading circuit is used for outputting a constant voltage signal to the driver according to the output from the angle sensor. According to the embodiment, the noise power of the output signal of the angle sensor can be reduced, and a signal-to-noise ratio is improved.
Description
technical field [0001] The invention relates to the technical field of laser projection. More specifically, it relates to a MEMS scanning mirror and a laser projector. Background technique [0002] A laser projector using a MEMS (Micro Electro Mechanical System, Micro Electro Mechanical System) scanning mirror has the advantages of low cost and miniaturization, and has a broad market prospect. [0003] Traditional MEMS scanning mirrors often use torsion bar actuation. The mirror is tilted and twisted by two, three or more torsion bars supporting the mirror to perform optical scanning. Resonant drive is used to achieve large scans. Angle, it is necessary to match the resonant frequency of the tilting motion of the mirror with the driving frequency through structural design. [0004] When driving the MEMS scanning mirror or monitoring the mirror angle, in order to maintain the resonance state, the current method is to set an angle sensor for sensing the deflection angle of t...
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Login to View More IPC IPC(8): G02B26/08G03B21/00
CPCG02B26/0858G03B21/008
Inventor 林育菁畠山庸平
Owner GOERTEK INC