Performance of Tense Thin Film Torsion Bar for Large-Rotation and Low-Voltage Driving of Micromirror

Sasaki, Minoru; Yuki, S.; Hane, Kazuhiro

doi:10.7567/ssdm.2007.d-2-4

Cited by 3 publications

(9 citation statements)

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“…Adding tension in the torsion bar generates non-linear spring property in the torsion bar and makes the micromirror rigid to vertical displacement. Pull-in phenomena is suppressed and range of the mirror rotation is expanded [15,16]. The fabricated micromirror could rotate 7.7 degrees at 12V bias at static condition [17] whereas the conventional micromirror requires about 100 V at the most for its rotation [9].…”

Section: Micromirror Devicementioning

confidence: 91%

“…Whenever fingers are put between the coils, the induced voltage is almost unchanged. Mirror rotation angle is measured by optical lever method [15,16]. …”

Section: Experimental Setup For Wireless Drivingmentioning

confidence: 99%

“…Dimensions of the micromirror were 150µm × 114µm × 10µm. Resonance frequency f of mirror rotation was calculated from [15,16], where k θ is spring constant for torsion, I is inertial moment of micromirror, G is modulus of rigidity (65GPa), w, l, and t are width, length, and thickness of torsion bar, respectively. Using the dimensions of torsion bar and micromirror, the resonance frequency is calculated to 780Hz.…”

Section: Micromirror Devicementioning

confidence: 99%

“…Although piezoelectric driving achieves low power consumption [14], it includes toxic materials such as lead, which is harmful to human body. In terms of low power consumption, electrostatic driving is considered to be a promising method [1,9,[15][16][17]. However, some of the MEMS micromirror requires several tens of voltage for its actuation.…”

Section: Introductionmentioning

confidence: 99%

“…One of the reasons is that conventional micromirror devices require about 100 V at the most for actuation. So far, we have realized low-voltage-driving micromirror by improving the structural design of the micromiror device [15][16][17]. Energy required for the actuation is transferred to the device inside the human body through the skin (sum of the thicknesses of epidermis and dermis: 1-2 mm) [18] and subcutaneous fat (thickness: 20-40 mm) [19,20].…”

Section: Introductionmentioning

confidence: 99%

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Wireless Driving of a Micromirror Device by Electoromagnetic Excitation Tuned to Mechanical Resonance of Rotation

Kumagai

Ohnishi

Sasaki

2012

JAMDSM

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Wireless driving of a micromirror device is achieved by electromagnetic excitation tuned to the mechanical resonance of the mirror rotation. The micromirror used is designed for low-voltage-driving. Static mirror rotation angle is 7.7 deg. at 12 V bias. The micromirror is connected to a coil for receiving the driving energy through electromagnetic induction. Magnetic field of 19.3 mT at the surface of the first coil induces 0.6 V at the second coil that is 24 mm apart from the first coil. An LC resonance circuit is incorporated in the second coil system to enhance the induced voltage. The LC resonance frequency is tuned to induce the mechanical resonance of the micromirror device. When the separation distance between the first and second coils is 24 mm, the voltage induced by the LC resonance is 1.43 V. Mirror rotation angle is 0.3 deg. for half stroke is achieved. It is expected that the rotation angle is expanded by increasing the Q factors of the electrical circuit and mechanical resonance of the micromirror. These will be achieved by reducing the loss in the electrical circuits and packaging the micromirror device in vacuum with hermetic seal.

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Section: Micromirror Devicementioning

confidence: 91%

“…Whenever fingers are put between the coils, the induced voltage is almost unchanged. Mirror rotation angle is measured by optical lever method [15,16]. …”

Section: Experimental Setup For Wireless Drivingmentioning

confidence: 99%

Section: Micromirror Devicementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Wireless Driving of a Micromirror Device by Electoromagnetic Excitation Tuned to Mechanical Resonance of Rotation

Kumagai

Ohnishi

Sasaki

2012

JAMDSM

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A novel infrared detector using highly nonlinear twisting vibration

Yamazaki

Ogawa

Kumagai

et al. 2014

Sensors and Actuators A: Physical

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A new resonant infrared (IR) detector is proposed. The twisting motion of the thin film torsion bar is first used. The resonant frequency gives the information of the temperature change of the moving element caused by IR absorption. The dynamic sensing using the electrostatic force can remove the drift without the heat generation. The large nonlinearity of the thin film torsion bar combined with the frequency measurement increases the advantage of the high sensitivity. The IR detector is fabricated by the surface micromachining using sub-m thick poly-Si film. Its structure consists of two parts. One is the thin film torsion bars and another is the bending center part. They can be basically designed separately. The center part has bi-layer structure to induce bending against the temperature increase caused by the IR absorption. One fabricated IR detector has the resonant frequency of about 35kHz and shows the sensitivity of 30Hz/K and the shifting ratio of 830ppm/K. This sensitivity is larger than the previously reported Si detectors. The shifting ratio is larger than devices including the high-frequency quartz and ZnO detectors.

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Low voltage operation electrostatic comb drive micro-mirror for laser scanning display

Chu¹,

Ngoc²,

Hane³

2012

Vietnam J. Mech.

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Electrostatic comb drive micro-mirror has limitation of high operation voltage, which has limited its practice use. Recent developments in decreasing operation voltage are promising for mobile micro-mirror. Especially, the operation voltage is decreased substantially by removing the air friction of comb-drive micro-mirror at a high resonant frequency when the mirror is operated at low pressure. Removing simultaneously the air friction and anchor loss, electrostatic comb-drive micro-mirror operating at a few voltages at a high resonant frequency becomes possible. This paper presents our recent developments as well as emerging techniques introduced in literature for decreasing the operation voltage of electrostatic comb drive micro-mirror. Methods for decreasing the operation voltage at large rotation angle and high scan frequency for application in the laser scanning display are focused to discuss in this paper.

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Performance of Tense Thin Film Torsion Bar for Large-Rotation and Low-Voltage Driving of Micromirror

Cited by 3 publications

References 0 publications

Wireless Driving of a Micromirror Device by Electoromagnetic Excitation Tuned to Mechanical Resonance of Rotation

Wireless Driving of a Micromirror Device by Electoromagnetic Excitation Tuned to Mechanical Resonance of Rotation

A novel infrared detector using highly nonlinear twisting vibration

Low voltage operation electrostatic comb drive micro-mirror for laser scanning display

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