Translated article from EDN Taiwan

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MEMS scanning mirror mini projectors, advanced technology vehicles with HUD
In the months before the United States held in 2016-MEMS and sensors Summit (MEMS &Sensors Executive Congress), there are many new MEMS technology and applications are introduced to the participants, now let us take a look at the latest MEMS technology can be used in those applications ...

In the months before the United States held in 2016-MEMS and sensors Summit (MEMS &Sensors Executive Congress), the author met with MicroVision's Director of systems engineering and the application of advanced Jari Honkanen, he showed the company's stunning technology of MEMS micro scanning mirror (Figure 1).

Figure 1 miniature MEMS scanning mirror is smaller than your thumb.

MicroVision and meaning method semiconductor (ST) in November early on announced will in laser beam scan (LBS) technology field for products development, and sales and promotion of cooperation, now this two home company focuses on Yu LBS solution programme in micro projector and looked up display (HUD) application market of promotion, also for March including virtual/spread increased real border (VR/AR), and 3D sense measuring and advanced driving auxiliary system (ADAS), emerging application very interested in.

In addition, MicroVision and ST is also looking forward to the future possibility of seeking cooperation in technology development, including common LBS product development blueprint, combined with ST's strengths in design and manufacturing, as well as the MicroVison development solutions expertise.

Industry is actively into the field of laser technology, Infineon (Infineon), achieved in October through the acquisition of Innoluce light (LIDAR) technology expertise ADI announced the acquisition of Vescent LBS of Photonics technologies in mid-November, the goal is to let the vehicle became the mainstream application of the LIDAR system. I expect the company to continue into the field of laser technology.

MicroVision's MEMS scanning mirror design (Figure 2) key features is that there is only one driver signal input to the MEMS; in order to produce the two-axis motion (biaxial motion), horizontal and vertical movement of the wave just to be overlapping (Figure 3).

Figure 2 MicroVision MEM DMD module contains a suspension containing a micro-electronic coil gimbal (gimbal frame) mirror MEMS chip installed around a permanent magnet to provide magnetic; through the MEMS coil provides current, universal bracket will have a magnetic moment, and have a component along the axis of rotation you want. (Source: MicroVision)

One of the magnetic component of Figure 3, universal support around the Flex suspension (flexure suspension) rotation (left), another component is used to influence the scanning mirror resonant mode of vibration, reflector can rotate the BRACKET around the Flex suspension, Vientiane. (Source: MicroVision)

Composite micro-mirror driving waveform, 60Hz vertical zigzag function (sawtooth function) as well as horizontal scanning resonant high frequency sine wave (sinewave) stack (Figure 4).

Figure 4 composite waveforms. (Source: MicroVision)

Two of the desired scanning angle position feedback using piezoelectric (piezo-resistive,PZR) stress; the sensors produced in micro-technology, Flex mirror suspended gimbal deflection on the suspension (Figure 5).

Figure 5 from the piezoelectric strain sensor on MEMS scanning mirror feature to generate vertical scan position feedback; the position feedback system can improve the projector display time and environmental conditions of stability. (Source: MicroVision)

Integrated in the MEMS scanning mirror Red, blue and green lasers diode, to form a compact color display engine (Figure 6); using MEMS technology to combine small lasers, the scan mirror the system volume contains the light source is less than 5 cubic centimeters (cm), height of only 6 mm (mm).

Figure 6 the overall MEMS scanning mirror and laser light system structure (source: MicroVision)

Applications in Pico-projectors, MEMS scanning mirror combined with laser light source projector technology can achieve smaller than a coin, and can provide any projection no distortion on the surface of 1,280x720 picture quality, brightness up to 25 lumens, projection distance of 1.1 meters can produce a diagonal image size of about 1 meter.

MicroVision in the MEMS and sensors at the Summit, introduced the company's MEMS scanning mirror technology application in automotive heads-up display; on the driver through the windscreen will be able to see information such as traffic projections, without leaving the front sight. In addition, the Honanen also introduced the company to match the near-infrared laser beam scanning technology (IR) laser and IR detectors, MEMS scanning mirror technology built LIDAR systems.

The advantage of MEMS scanning LIDAR system, is able to provide a high resolution of horizontal and vertical scan, resolution and frame rate, and can dynamically change the purpose; in addition, the same scanning LIDAR technology, also depending on the application or its driver, supports low-speed, high resolution and high speed and lower resolution video capture.