Source: http://www.google.com/patents/US7907320?dq=U.S.+Patent+%23+5,723,324
Timestamp: 2014-07-11 15:01:28
Document Index: 21952210

Matched Legal Cases: ['art 33', 'art 33', 'art 33', 'art 33', 'art 33', 'art 33']

Patent US7907320 - Micromirror device with a single address electrode - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign in<nobr>Advanced Patent Search</nobr>PatentsA micromirror device comprises a plurality of mirrors arranged on a substrate, an elastic hinge for supporting each mirror to be deflectable, an address electrode having first and second regions arranged across the deflection axis of each mirror, a driving circuit for controlling a deflection of the...http://www.google.com/patents/US7907320?utm_source=gb-gplus-sharePatent US7907320 - Micromirror device with a single address electrodeAdvanced Patent SearchPublication numberUS7907320 B2Publication typeGrantApplication numberUS 12/072,450Publication dateMar 15, 2011Filing dateFeb 25, 2008Priority dateFeb 26, 2007Also published asUS7649673, US7839561, US7907325, US20080204845, US20080218830, US20080218831, US20090174926, WO2008106141A2, WO2008106141A3, WO2008106180A1Publication number072450, 12072450, US 7907320 B2, US 7907320B2, US-B2-7907320, US7907320 B2, US7907320B2InventorsYoshihiro Maeda, Fusao Ishii, Hirokazu Nishino, Kazuma AraiOriginal AssigneeSilicon Quest Kabushiki-Kaisha, Olympus CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (15), Classifications (4), Legal Events (1) External Links: USPTO, USPTO Assignment, EspacenetMicromirror device with a single address electrodeUS 7907320 B2Abstract A micromirror device comprises a plurality of mirrors arranged on a substrate, an elastic hinge for supporting each mirror to be deflectable, an address electrode having first and second regions arranged across the deflection axis of each mirror, a driving circuit for controlling a deflection of the mirror, and a stopper provided in a position of making contact with the mirror in a deflected state of the mirror. When the mirror makes contact with the stopper, the potential of the mirror or the stopper changes.
a plurality of mirrors each supported on an elastic hinge disposed on a substrate for deflecting each of the mirrors to different deflection angles;
an electrode disposed on the substrate and connected to a driving circuit wherein said driving circuit applies a voltage to said electrode to deflect said mirror to said different deflection angles; and
a stopper is disposed on said substrate at a position for contacting and stopping said mirror when said mirror is deflected to a maximum deflection angle, and wherein said driving circuit changes a potential of said mirror or said stopper when said mirror is deflected to said maximum deflection angle and contacts with said stopper.
said driving circuit is further electrically connected to said mirrors via said elastic hinge.
each of said mirrors further has a plurality of said electrodes connected to said drive circuit for driving and deflecting each of said mirrors.
said elastic hinge is composed of a material having a predetermined resistance.
said stopper is composed of a first material and said mirror is composed of a second material wherein when said mirror is deflected to said maximum deflecting angle to contact said stopper thus having a predetermined resistance between said stopper and said mirror.
said drive circuit controls said mirror and said electrode to decrease a coulomb force between said mirror and said electrode when said mirror contacts with said stopper.
7. A micromirror device, comprising:
an electrode disposed on the substrate and connected to a driving circuit wherein said electrode is disposed at a position on said substrate for contacting and stopping said mirror when said mirror is deflected to a maximum deflection angle, and
said driving circuit changes a potential of said mirror when said mirror is deflected to said maximum deflection angle and contacts with said electrode.
8. The micromirror device according to claim 7, wherein
9. The micromirror device according to claim 7, wherein
each of said mirrors further has a plurality of said electrodes connected to said drive circuit for deflecting and stopping each of said mirrors.
10. The micromirror device according to claim 7, wherein
said driving circuit deflects said mirror to contact with said electrode when said mirror is deflected to a nearly horizontal deflection angle substantially in parallel to said substrate.
11. The micromirror device according to claim 7, wherein
said mirror is composed of a conductive material for transferring electric charges between said mirror said electrode when said mirror is deflected to contact and stopped by the electrode.
12. The micromirror device according to claim 7, wherein
said driving circuit changes a coulomb force applied between said mirrors and said electrode while the mirror is moving toward the electrode.
13. A micromirror device, comprising:
an address electrode disposed on the substrate for each of said mirrors;
a driving circuit connected to at least one of said address electrodes, and to said mirror via said elastic hinge;
a potential change electrode disposed on the substrate for each of said mirrors, wherein said potential change electrode is disposed at a position on said substrate for contacting and stopping said mirror when said mirror is deflected to a maximum deflection angle; and
said driving circuit changes a potential of at least one of said potential change electrodes and said mirror, and said address electrode in one of said mirrors of said potential change electrode when said mirror makes contact with said potential change electrode.
A micromirror is a microscopic mirror used in reflecting light. A deflectable micromirror device (DMD), that is, one composed of display elements implemented with a micro electromechanical system (MEMS) device configuration where an electric circuit is integrated on a silicon substrate and many micromirrors are arranged on the flat surface of the substrate, is generally known as a device using micromirrors. One can change the deflection angle of a micromirror surface on a conventional DMD by applying a voltage to two address electrodes positioned below each micromirror to generate a coulomb force F. Note that �deflection� referred to in this specification indicates the tilt of a micromirror surface. FIG. 1 is a circuit diagram that shows two driving circuits configured with memory cells with an SRAM configuration, which are connected to two address electrodes according to the conventional method.
As described in these patents above, in a DMD where two electrodes are provided on a substrate in one mirror element, the two driving circuits required for each of the two address electrodes occupy a large area on the substrate because the configuration of the two driving circuits corresponding to the two address electrodes is required. This imposes a severe restriction on the arrangement of a larger number of mirror elements on the substrate. Additionally, previous to this invention, there have been no methods for controlling one mirror element with a single address electrode in a micromirror device. Furthermore, there have been no methods disclosed for controlling a mirror element to deflect in two directions with high precision.
SUMMARY OF THE INVENTION A micromirror device according to a first preferred embodiment of the present invention is a micromirror device configured by arranging on a substrate a plurality of mirror elements each comprising a mirror, an elastic hinge for supporting the mirror to be deflectable, an address electrode having first and second regions arranged across the deflection axis of the mirror, a driving circuit that is connected to the address electrode and controls a deflection of the mirror, and a stopper provided in a position of making contact with the mirror in a deflected state of the mirror, wherein the potential of the mirror or the stopper changes when the mirror makes contact with the stopper.
The change of the potential of the mirror or the stopper is used as a timing signal for controlling a pulse signal, or as a reference signal such as a reset signal, etc. of the device.
A micromirror device according to a second preferred embodiment of the present invention is a micromirror device configured by arranging on a substrate a plurality of mirror elements each comprising a mirror deflectable with respect to the substrate, an elastic hinge, a potential change electrode which is provided in a position of making contact with the mirror, and the potential of which changes along with the mirror when making contact with the mirror, and a driving circuit that is connected to the potential change electrode, and controls the mirror.
Also in this case, the change of the potential of the potential change electrode or the mirror is used as a timing signal for controlling a pulse signal, or as a reference signal such as a reset signal, etc. of the device.
A micromirror device according to a third preferred embodiment of the present invention is a micromirror device configured by arranging on a substrate a plurality of mirror elements each comprising a mirror, an elastic hinge for supporting the mirror to be deflectable, an address electrode arranged between the mirror and the substrate, a driving circuit connected to the address electrode and to the mirror via the elastic hinge, and a potential change electrode arranged between the mirror and the substrate, wherein the voltage of any of the potential change electrode, the mirror, and the address electrode changes when the mirror makes contact with the potential change electrode.
In this case, the change of the voltage of any of the potential change electrode, the mirror, and the address electrode is used, whereby the change of the voltage can be used as a reference signal for various types of controls performed in the micromirror device.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram that shows two driving circuits configured with memory cells with an SRAM configuration, which are connected to two address electrodes according to the conventional method;
FIGS. 15D and 15E are charts that exemplifies a method for controlling the micromirror to change from the ON light state to the OFF light state by applying a multilevel voltage to the address electrode and/or the micromirror of a mirror element in the micromirror device, according to the present invention;
DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention discloses micromirror devices that include a plurality of mirror elements, with each mirror element controlled by a single address electrode and one driving circuit connected to the address electrode on a substrate.
First Preferred Embodiment FIG. 4A is a cross-sectional view of the mirror element 38 held in the initial state taken along the line IV-IV of FIG. 3 in the micromirror device according to the present invention. The configuration and the initial state of one mirror element in the micromirror device according to the present invention are described below with reference to FIG. 4A. In this configuration of one mirror element in the micromirror device according to the present invention, an insulation layer 40 is provided on a substrate 32. The mirror element also includes one driving circuit 37, for driving the micromirror, and one elastic hinge 36, which is situated on the insulation layer 40. The elastic hinge 36 supports one micromirror 31, and an address electrode 33 connected to the driving circuit 37 is situated below the micromirror 31. The address electrode 33 and the driving circuit 37, which is connected to the address electrode 33, electrically control the micromirror 31. The elastic hinge 36 is connected to a hinge electrode 34 through an opening (not shown) in the insulation layer 40. The hinge electrode 34 is grounded or held at a predetermined voltage. One mirror element of the micromirror device, according to the present invention, is configured as described above. Arranging multiple mirror elements 38, as described above, on the substrate 32, as shown in FIG. 3, can configure a micromirror device.
In this invention, the right and the left regions of the single address electrode, which protrude from the substrate and are positioned on both sides of the elastic hinge or the deflection axis of the micromirror, are referred to as first and second electrode parts, respectively, unless otherwise noted, and a coulomb force is generated between the first or the second electrode part and the micromirror by applying a voltage to the address electrode 33. The use of the term, �applying a voltage�, referred to in this specification, is a paraphrase of changing a potential to a predetermined waveform.
Second Preferred Embodiment According to the second preferred embodiment, the ON or the OFF light state can be implemented by tilting the micromirror with mutually different coulomb forces generated respectively between the micromirror and the first electrode part, and between the micromirror and the second electrode part by applying a voltage to the single address electrode based on the assumption that the initial state is the intermediate light state.
In FIG. 6A, the position of the micromirror 31 is held in the initial state, that is, the intermediate light state up to a time t1, and the voltage is not applied to the address electrode 33 during this time period. When the micromirror 31 is deflected from the initial state to the OFF light state, the micromirror 31 is tilted toward the first electrode part 33 a (of FIG. 5A) or 33 c (of FIG. 5C) of the address electrode 33 by applying the voltage to the address electrode 33 as indicated by the time t1 to a time t2. As a result, the micromirror 31 can be controlled to deflect to the OFF light state. This can be understood according to the principle that the coulomb force F represented by the following equations (1) and (2) is more intensified and applied between the first electrode part 33 a or 33 c with the larger area of the address electrode 33 and the micromirror 31, since the electrode part 33 a or 33 c with the larger area can store a larger amount of charge, than the electrode part 33 b (of FIG. 5A) or 33 d (of FIG. 5D) with the smaller area when the distance r between the micromirror 31 and the first electrode part 33 a or 33 c on the OFF light side of the address electrode 33 is the same as that between the micromirror 31 and the second electrode part 33 b or 33 d on the ON light side of the address electrode 33 in the initial state. [[NOTE: please re-read this paragraph as I'm not sure what it's saying]]
F = 1 4 ⁢ π ⁢ ⁢ r 2 � 1 ɛ ⁢ q 1 ⁢ q 2 ( 1 ) Where r is the distance between the address electrode 33 and the micromirror 31, ∈ is permittivity, and q1 and q2 are the amounts of charge stored.
F=k′eSV 2/2h 2 (2)
The series of operations for causing the micromirror 31 to freely oscillate by tilting the micromirror 31 in the initial state, namely, the operations for causing the micromirror 31 to freely oscillate after tilting the micromirror 31 from the state horizontal to the substrate 32 is hereinafter referred to as �initial operations� in this specification.
Third Preferred Embodiment The third preferred embodiment discloses the micromirror device that includes a plurality of mirror elements in each of which the micromirror can be controlled to deflect to the ON and the OFF light states by making the right and the left regions of the address electrode with different heights. The address electrode is formed as one piece and arranged across the elastic hinge or the deflection axis of the micromirror.
Fourth Preferred Embodiment The fourth preferred embodiment discloses the configuration to control the micromirror to deflect to the ON or the OFF light state with a coulomb force. The top surfaces of the right and the left regions of the single address electrode formed as one piece and arranged across the elastic hinge 36 or the deflection axis of the micromirror have layers with different permittivities in one mirror element in the micromirror device according to the fourth preferred embodiment of the present invention.
Fifth Preferred Embodiment The fifth preferred embodiment discloses the micromirror device where the micromirror is controlled to deflect to the ON and the OFF light states with a coulomb force. The regions of the micromirror respectively face and correspond to the first and the second electrode parts of the single address electrode across the elastic hinge or the deflection axis of the micromirror are formed with materials with different permittivities.
Sixth Preferred Embodiment The sixth preferred embodiment discloses the micromirror device including a plurality of mirror elements in each of which the micromirror can be controlled to deflect to the ON or the OFF light state with a coulomb force. The Coulomb force is generated by connecting an electrode to which a predetermined voltage is applicable to either of the regions of the micromirror. The regions of the electrode respectively face and correspond to the first and the second electrode parts that are respectively positioned on the right and the left sides of the deflection axis in the single address electrode disposed across the elastic hinge or the deflection axis of the micromirror.
Seventh Preferred Embodiment The seven preferred embodiment according to the present invention discloses the micromirror device that can control the micromirror to deflect to the ON or the OFF light state with a coulomb force by forming an address electrode as one piece in one mirror element. The micromirror has flat surface for reflecting incident light. The regions of the micromirror respectively face and correspond to the first and the second electrode parts of the single address electrode across the elastic hinge or the deflection axis of the micromirror have different thickness.
Eighth Preferred Embodiment The eighth preferred embodiment discloses the micromirror device where the micromirror can be controlled to deflect to the ON or the OFF light state. A coulomb force is combined with the elasticity of elastic hinges by using elastic members with different elasticity coefficients respectively for the deflection directions of the micromirror. The address electrode across the elastic hinge or the deflection axis of the micromirror is formed as one piece in one mirror element.
Ninth Preferred Embodiment The ninth preferred embodiment discloses the micromirror device where the address electrode is formed as one piece, The micromirror is controlled to deflect to the ON or the OFF light state with a coulomb force by arranging an elastic hinge for supporting the micromirror in a position away from the gravity center of the micromirror.
Tenth Preferred Embodiment The tenth preferred embodiment discloses the configuration implemented by adding in the first to the ninth preferred embodiments an electrode for detecting the position of the micromirror or for determining the timing to change the operation of the micromirror when the micromirror makes contact with the electrode and further describes the principle for detecting the position of the micromirror. The detection of the position of the micromirror referred to in this invention is to detect that the micromirror is tilted to the ON or OFF light side, or neither of the sides, or to determine the timing for the micromirror in changing from the deflected state to another state.
Eleventh Preferred Embodiment The eleventh preferred embodiment discloses the micromirror device where the micromirror is controlled to tilt with the coulomb force generated between the first or the second electrode part of the single address electrode to which the voltage is applied. The micromirror is controlled to always tilt to a particular ON or OFF light state regardless of the current state of the micromirror.
FIGS. 15A to 15E assume that the address electrode or the micromirror is configured so that the coulomb force applied between the electrode part on the ON light side of the address electrode and the micromirror becomes higher than that applied between the electrode part on the OFF light side of the address electrode and the micromirror. In order to apply the multilevel voltage to the micromirror, the address electrode may be grounded.
This specification has disclosed the exemplary embodiments of the micromirror devices with detail descriptions. However, it is evident that various modifications and changes may be made to these embodiments without departing from the spirit and the scope of the present invention. Accordingly, this specification and the drawings are not to be taken in a limiting sense but to be regarded as specific embodiments.
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