An electrostatic 1 dimensionally (1D) scanning mirror for HD resolution display is introduced. Vertical comb drive was
used to tilt the micro mirror. To minimize the moment of inertia and maximize the tilting angle of the mirror having the
diameter of 1.6 mm, the rib was patterned on the backside of the mirror surface and optimized. Via the finite element
simulation, the dynamic deformation of 45nm was achieved within the reflecting area in operating resonant mode thanks
to the optimized rib structure. The actuating part of scanner was also optimized manipulating with several design
variables to get maximum tilting angle. As the fabrication result, mechanical tilting angle of ±12.0 degree was achieved
with the resonant frequency of 24.75kHz and the sinusoidal driving voltage of 280Vpp. For stable resonant motion of the
scanner, the feedback control algorithm was realized in the driving circuit. Rigorous reliability characterization was
carried out using statistical analysis on the fabricated samples. As a result, HD-resolution image with 720 progressive
horizontal lines was demonstrated.
Since lasers have the most saturated colors, laser display can express the natural color excellently. Laser scanning display has merits of simple structure and high optical efficiency. We designed a new scanning mirror which has a circular mirror plate with an elliptical outer frame and is electrostatically driven by vertical combs arranged at the outer frame. This eye-type mirror showed a larger deflection angle compared to the rectangular and the elliptical mirrors. To increase the driving force twice, stationary comb electrodes are arranged at the upper and lower sides of the moving comb fingers, together. The diameter of the mirror plate is 1.0 mm, and the lengths of the major and minor axes of the outer frame are 2.5 mm and 1.0 mm, respectively. Using this scanning mirror, we obtained an optical scanning angle of 32 degrees when driven by the ac control voltage of the resonant frequency in the range of 22.1 ~ 24.5 kHz with the 100 V dc bias voltages. We demonstrated the full color XGA-resolution video image with the size over 30 inches using an eye-type scanning mirror. The successful development of compact laser TV will open a new area of home application of the laser light.
The laser TV using blue, green diode-pumped solid state lasers and a red diode laser is developed. The wavelengths of the blue, green and red are 457 nm, 532 nm and 648 nm, and the output powers are 350 mW, 700 mW and 500 mW, respectively. The power levels of lasers are adjusted for white color balance. The polygon mirror and the galvanometer are used for horizontal scanning and vertical scanning, respectively. The image size of 80 inches with high-brightness and VGA resolution (640 X 480 Progressive scanning) is obtained. The acousto-optic modulator (AOM) is fabricated for laser beam modulation, for which the carrier frequency of 350 MHz for XGA resolution is applied. TeO2 crystal, which is cut at Brewster angle, is used as an optical medium and LiNbO3 is attached as a transducer. In order to get a compact size, low cost, low-power consumption and lightweight, a scanning mirror using MEMS technology is fabricated by the size of 1500 micrometers X 1200 micrometers . This scanning mirror can be used as a galvanometric vertical scanner for laser TV.
A 1500 micrometers X 1200 micrometers silicon scanning mirror for laser display has been fabricated. This scanning mirror is mainly composed of two structures having vertical comb fingers. By anodic bonding of the silicon wafer and the Pyrex glass substrate, and followed deep ICPRIE (Inductively Coupled Plasma Reactive Ion Etching), isolated comb electrodes were fabricated at the lower structure. But in this anodic bonding, gold signal lines for electrical connection to the electrodes, which were inserted between silicon and Pyrex glass, were cut off by mechanical pressure or damaged to agglomerate by diffusion. To remove these phenomena, Pyrex glass was trenched about 2000 Angstroms in depth in the shape of signal lines, and Cr/Au signal lines were formed along the etched grooves about 500 Angstroms/3500 Angstroms in depth, and then annealed at 400 degree(s)C, N2 atmosphere, for 1 hour before anodic bonding. As a result, gold signal lines were successfully fabricated and the contact resistance was acquired below several tens ohms. By flip chip bonding, the upper and lower structure having vertical comb fingers were assembled. Vertical comb fingers of two structures were aligned with a microscope and the frames of two structures were bonded at 300 degree(s)C for 20 sec. using the eutectic bonding material, electroplated AuSn. Using these bonding technologies, the scanning mirror was successfully fabricated and it could be used for laser display as a galvanometric vertical scanner.