Abstract:
Disclosed is a micromirror actuator with the degrees of freedom of two axes operated by an electrostatic force. The micromirror actuator comprises: a substrate provided with an insulating layer formed thereon; two lower columns spaced from each other by a designated distance, and formed on the insulating layer; a first torsion bar extending over upper surfaces of the lower columns; a second torsion bar formed so that the first and second torsion bars are orthogonal to each other; four electrodes, each disposed in four areas formed by the orthogonal crossing of the first and second torsion bars, formed on the insulating layer; two upper columns formed on an upper surface of the second torsion bar so that upper surfaces of the upper columns are located at higher positions than upper surfaces of the electrodes; and a micromirror located on the upper surfaces of the upper columns so that the micromirror is supported by the upper columns. In the micromirror actuator, the micromirror is elevated to a desired height by means of two upper columns, and the dimensions of its structure are reduced by locating torsion bars under the micromirror. Further, the micromirror actuator allows the micromirror to be selectively tilted centering on two torsion bars depending on electrodes to which voltage is applied, thus being used as a three-dimensional optical switch.
Abstract:
Disclosed are a micromirror device made in a simple structure using interdigitated cantilevers and having two stable rotational states, and applications thereof. The micromirror device comprises: (a) a substrate; (b) at least two protruded support posts arranged protrudedly in two columns of left and right sides on the substrate and apart by a predetermined interval from each other; (c) multiple cantilevers formed in parallel with the substrate, each having one end attached at the upper end portion of the respective protruded support posts and made in a thin strip having an elastic restoring force, wherein the cantilevers adjacent to each other are arranged to be parallel and interdigitated; (d) mirror support posts coupled to upper portions of the other ends of the cantilevers; (e) a mirror attached on upper portions of the whole mirror support posts and supported by the mirror support posts; and (f) two electrodes formed at left and right sides on the substrate, for providing an electrostatic force to the mirror, wherein the micromirror device reflects light incident into the mirror in different directions from each other by using an electrostatic force due to a voltage applied between the electrodes and the mirror, and the elastic restoring force of the cantilevers. The micromirror device can drive the mirror in two directions and adjust a rotational angle of the mirror using the electrostatic force due to a potential difference between the electrodes and the mirror for reflecting incident light, and the elastic restoring force of the cantilevers.
Abstract:
Disclosed is an electrostatic actuator. A multi-layered auxiliary electrode is further arranged between main electrode and actuating body, and positive charge or negative charge is applied to main electrode, respective auxiliary electrodes, and actuating body such that electrostatic attractive force is generated between auxiliary electrodes adjacent to the main electrode, between adjacent auxiliary electrodes, and between auxiliary electrodes adjacent to the actuating body. According to the invention, distance between the induced charges is shortened, so that electrostatic attractive force therebetween increases, thereby capable of maintaining an actuating range equal to or larger than the conventional electrostatic actuator. The electrostatic actuator according to the present invention can be applied to various MEMS devices, such as an optical switch in which a mirror is formed in the actuator, a radio frequency (RF) switch, or a variable electrostatic capacitor, or the like.