Method for Operating a Micromirror Device with Electromechanical Pulse Width Modulation
The present invention is related to a method for operating by pulse width modulation a micromirror device (50) comprising the steps of: - providing a micromirror device comprising at least one micromirror element (10) being electrostatically deflectable around a rotation axis (30) between at least two positions being a first position and a second position, by applying voltage signals to at least four electrodes (21, 22, 23, 24) controlling said micromirror element, the first and second electrodes (21, 22) being located on one side of the rotation axis, and the third and fourth electrodes (23, 24) on the other side; - associating an intermediate value of intensity to said micromirror (10) element during a time frame, said intensity being comprised between a first value and a second value, said first value corresponding to said first position and said second value corresponding to said second position; - switching the micromirror element (10) between the first position and the second position and vice-versa so that the micromirror element (10) is either in the first position or in the second position whereby the intermediate value of intensity between said first value and said second value is obtained, said intermediate value of intensity corresponding to the ratio of the periods of time in a time frame in which the micromirror element is either in the first position or in the second position; characterised in that said switching is obtained by applying fixed voltage signals to the second and third electrodes (22, 23) during the time frame and said fixed voltage signals being kept constant during half of the time frame, and periodic voltage signals having a period equal to the length of the time frame to the first and fourth electrodes (21, 24).
DE SMET HERBERT [BE]; BEERNAERT ROEL [BE]
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