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Research paper : The aerosol deposition method (J. Akedo et al.)−126 Synthesiology - English edition Vol.1 No.2 (2008) material for the body of MEMS optical scanner shown in Figure 5. The whole scanner structure including mirror and torsion beam was formed by a punching process, and the piezoelectric film was directly formed on the structure using the AD method. As the AD piezoelectric film formed on the substrate undergoes expansion and contraction by external electric field, bending deflection is induced in the entire substrate (function as uni-morph actuator), Lamb wave is produced, mirror is excited by resonance, and laser light reflected by the mirror is scanned at high speed. Figure 7 shows the performance comparison with an optical scanner manufactured by conventional Si-MEMS when same driving voltage has been used. The horizontal axis shows the resonance frequency and the vertical axis shows the mirror size x scanning angle of light beam as standard assessment index for the deflection angle of the mirror. The resonance frequency could be designed at wide range between 100 Hz ~ 90 kHz in air, and maximum 95° was obtained as scanning angle of the light beam. Also, by using stainless steel material that was treated by ultra-precise polishing process, punch processed mirror achieved flatness of about /4 ~ /8 for 1 by 1 mm2 mirror size, making it applicable for this optical scanner. When Si wafer is used, it is impossible to achieve mirror scanning angle at 10 kHz or more, because the torsion beam is damaged when the yield limit is surpassed and resonance frequency decreases. As shown in Figure 8, as a result of continuous motion test at maximum scanning frequency of 61 kHz and at maximum light beam scanning angle of 75° for over one year, there was no decrease of resonance frequency or deterioration of light beam scanning angle, confirming that practical durability was achieved from perspective of metal fatigue. Also, impact resistance was significantly improved by using stainless steel material, making possible its implementation in mobile devices and vehicle-mounted devices. Moreover, the stainless steel structure allowed the scanner itself to be used as a lower electrode, manufacturing process being greatly simplified compared with Si-MEMS or other optical scanners that require the fabrication of lower electrode. Since the initial cost for facility could be kept lower compared to conventional Si microfabrication facility, the cost of a device is expected to be also reduced.These results indicate that, for realizing high-speed optical scanner with large scanning angle, both high performance and cost reduction could be achieved when conventional design philosophy based on silicon micromachining could be exceeded by maximizing the advantage of the AD method which enables direct formation of excellent quality piezoelectric films[9] on metal substrate, and by combining this advantage with conventional mechanical processing technology.4.3 Application to multi-product variable production systemTo investigate the efficiency of the AD method in the above-mentioned optical scanner manufacturing at production level and, as an attempt for application to sensor and actuator parts for custom-made medical micro-devices for which multi-product variable production is required, we developed Fig. 8 Durability of metal-base optical scanner.Fig. 10 AD devices in various scales.Elapsed number of daysResonance frequency (kHz)7060504030201000100200300400500600(2006/3/6~), 61 kHz,33°(2006/12/14~), 30.5 kHz,32°(2006/9/15~), 15.3 kHz,43°(2006/4/3~), 6.4 kHz,75°Four series punch press (formation of scanner structure)Micro AD device (formation of piezoelectric film)Micro electric furnace (heat treatment process)Ink jet device (wiring process)Operation check・Combine basic cells (W500 × D800 × H1200)・Basic cell can be transported ーSmall enough to be moved by one person ーCan be re-assembled easily・Press machine and AD coating are incorporated ーFive units (press, AD, annealing, IJ wiring, and test) for the trial・Runs on AC 100 VFig. 9 On-demand MEMS manufacturing system.Compact desktop deviceGeneral use experimental deviceLarge device for mass productionSmall experimental deviceFreedom of device size is high due to simplicity of the coating method!Zero gravity experiment on aircraft(Size of coating surface:50 cm×50 cm)(Size of coating surface:5 cm×5 cm)(Size of coating surface:1 cm×1 cm)(Size of coating surface:2 cm×2 cm)(54)−

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