Wafer-level vacuum packaged resonant micro-scanning mirrors for compact laser projection displays

Abstract

Scanning laser projection using resonant actuated MEMS scanning mirrors is expected to overcome the current limitation of small display size of mobile devices like cell phones, digital cameras and PDAs. Recent progress in the development of compact modulated RGB laser sources enables to set up very small laser projection systems that become attractive not only for consumer products but also for automotive applications like head-up and dash-board displays. Within the last years continuous progress was made in increasing MEMS scanner performance. However, only little is reported on how mass-produceability of these devices and stable functionality even under harsh environmental conditions can be guaranteed. Automotive application requires stable MEMS scanner operation over a wide temperature range from -40° to +85°Celsius. Therefore, hermetic packaging of electrostatically actuated MEMS scanning mirrors becomes essential to protect the sensitive device against particle contamination and condensing moisture. This paper reports on design, fabrication and test of a resonant actuated two-dimensional micro scanning mirror that is hermetically sealed on wafer level. With resonant frequencies of 30kHz and 1kHz, an achievable Theta-D-product of 13mm.deg and low dynamic deformation <20nm RMS it targets Lissajous projection with SVGA-resolution. Inevitable reflexes at the vacuum package surface can be seperated from the projection field by permanent inclination of the micromirror

MEMS Mirror for Low Cost Laser Scanners

“…MEMS scanning mirrors have been used in many different applications as for instance barcode scanners, laser printers, endoscopes, laser scanning microscopes or laser projection displays [1]. Typically MEMS mirrors have a mirror aperture size within the range of 0.5 to 2 millimetres.…”

High-level modeling of resistor string based digital-to-analog converters

“…The DAC is used in an integrated laser projection system [17] that can be used in high volume applications such as automotive head-up display, display projection of handheld devices (mobile phones, PDA) and projection of virtual keyboards. The converter is used to drive a high voltage fully-differential amplifier [18].…”

Wafer level vacuum packaging of scanning micro-mirrors using glass-frit and anodic bonding methods

“…Taking into account that micro-mirrors are prospective candidates to be integrated also in mobile devices, such as smart phones, e.g. as a microbeamer [3,4] the high driving voltage is certainly a big disadvantage for mobile applications due to high power consumption. The high power consumption does not come directly from the electrostatic actuator itself, but mainly from the electrical circuits, like voltage pumps, required to generate the high driving voltage on a mobile platform.…”