Source: http://www.google.com/patents/US20020031294?dq=7,468,661
Timestamp: 2013-12-05 06:24:35
Document Index: 184200994

Matched Legal Cases: ['art 30', 'art 30', 'art 30', 'arts 62', 'art 30', 'art 30', 'art 40', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 65', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 30', 'art 40', 'art 30', 'art 40']

Patent US20020031294 - Optical switching device and image display device - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Advanced Patent Search | Sign inAdvanced Patent SearchPatentsAn optical switching device comprises: a light guide including a total reflection plane capable of totally reflecting light thereby transmitting the light; a switching part capable of, at a position where its extraction plane is in close contact with the total reflection plane, capturing evanescent light...http://www.google.com/patents/US20020031294?utm_source=gb-gplus-sharePatent US20020031294 - Optical switching device and image display devicePublication numberUS20020031294 A1Publication typeApplicationApplication numberUS 09/991,336Publication dateMar 14, 2002Filing dateNov 14, 2001Priority dateJan 20, 1998Also published asDE69830153D1, DE69830153T2, EP0969306A1, EP0969306A4, EP0969306B1, US6381381, US6438282, WO1999036824A1Publication number09991336, 991336, US 2002/0031294 A1, US 2002/031294 A1, US 20020031294 A1, US 20020031294A1, US 2002031294 A1, US 2002031294A1, US-A1-20020031294, US-A1-2002031294, US2002/0031294A1, US2002/031294A1, US20020031294 A1, US20020031294A1, US2002031294 A1, US2002031294A1InventorsHirokazu Ito, Shunji Kamijima, Takashi Takeda, Masatoshi YonekuboOriginal AssigneeTakashi Takeda, Masatoshi Yonekubo, Hirokazu Ito, Shunji KamijimaReferenced by (19), Classifications (10), Legal Events (2) External Links: USPTO, USPTO Assignment, EspacenetOptical switching device and image display deviceUS 20020031294 A1Abstract An optical switching device comprises: a light guide including a total reflection plane capable of totally reflecting light thereby transmitting the light; a switching part capable of, at a position where its extraction plane is in close contact with the total reflection plane, capturing evanescent light and reflecting the captured light thereby outputting it; and a driving part for driving the optical switching part. The light guide, the switching part, and the driving part are laminated in this order into a multilayer structure. The employment of the multilayer structure makes it possible to optimize the respective layers independently of one another. The extracted light does not pass through the driving part. This allows the driving part to be optimized so as to achieve an optical switching device capable of operating at a high speed with low power consumption. Thus, it is possible to provide a low-loss and high-contrast optical switching device using an evanescent wave, which can respond at a high speed. Images(30) Claims(1)
[0191] In the previous embodiment, an asymmetric electrostatic distribution is obtained by forming the electrode 62 or 60 such that the shape thereof or the distance therebetween becomes asymmetric. A driving force asymmetric about the center of gravitation of the switching part 30 may also be exerted on the switching part 30 by controlling the timing of applying an electrostatic force. [0192]FIG. 35 illustrates an optical switching device 1 in which the electrode 62 of the switching part 30 is divided into two parts 62 a and 62 b so that an electrostatic force may be applied at times different between the regions 12 a and 12 b left and right to the geometric center line 14. In this example, the electrode 62 is divided along the geometric center line 14 into two electrodes 62 a and 62 b which are symmetrical to each other about the geometric center line 14. By supplying electric power to the electrodes 62 a and 42 b at different times, a driving force having a distribution asymmetric about the geometric center line 14 can be exerted on the switching part 30. [0193]FIGS. 36 and 37 schematically represent the operation of the present example of optical switching device 1. FIG. 38 is a timing chart representing the operation (control) of supplying electric power from power supplies 61 a and 61 b to the respective electrodes 62 a and 62 b. When no electric power is supplied from the power supplies 61 a and 61 b to the left and right electrodes 62 a and 62 b, the switching part 30 is urged by the yokes 50 and 52 of the driving part 40 such that the extraction plane 32 is in an on-state (at the first position) in which the extraction plane 32 is in intimate contact with the total reflection plane 22 as shown in FIG. 36(a). [0194] When the power supply 61 a is turned on at time t 31 thereby supplying electric power to the electrode 62 a in the left region 12 a, an electrostatic force is generated in the left region 12 a. When the electrostatic force reaches a certain magnitude at time t 12, the switching part 30 starts to move in a tilted fashion as shown in FIG. 36(b). As a result of the tilting of the extraction plane 32 with respect to the total reflection plane 22, a gap (space) 17 is created and thus the switching part 30 comes into an off-state. As the space 17 gradually increases in volume, air 16 smoothly flows into the space 17, and thus the switching part 30 quickly moves without encountering a large air resistance. [0195] When the power supply 61 b is turned on to supply electric power to the electrode 62 b in the right region 12 b at time t 33 after time T 10 has elapsed since time t 31, an electrostatic force is exerted on the switching part 30 also in the right region 12 b. As a result, the switching part 30 tilted at a certain angle further receives a separation force in the right region and moves toward the second position while maintaining the angle as shown in FIG. 37(a). Because the tilted angle of the switching part 30 with respect to the moving direction is maintained during the movement, the air resistance becomes small and thus the switching part 30 can move at a high speed. This allows the switching part 30 to respond at a required speed with reduced electrostatic force. That is, the optical switching device 1 can be driven with less electric power consumption. [0196] When the switching part 30 approaches the electrode 60 toward the second stopping position as shown in FIG. 37(b), the switching part 30 comes into a substantially parallel state from the tilted state in the final stage of the movement from FIG. 37(a) to FIG. 37(b). Thus, during this final stage of the movement, air between the electrode 60 and the electrode 62 is smoothly transferred to the outside thereof. Therefore, also in this example of optical switching device 1, as described above, the switching part 30 is in the tilted state in the early, intermediate, and final stages of the movement, and thus the response speed can be further improved and the driving power of the optical switching device can be reduced. [0197] In the process of moving the switching part 30 from the second position to the first position, if electric power to the electrode 62 b in the right region 12 b is turned off at time t 14, the electrostatic force in the right regions 12 b is eliminated and the switching part 30 is tilted by the elastic force provided by the yoke 52 and the switching part 30 starts to move. When the electric power to the electrode 62 a in the left region 12 a is turned off at time t 35 after time T 11 has elapsed since t 14, the switching part 30 moves from the second position toward the first position while maintaining the properly tilted angle. When the switching part 30 reaches the first position at time t 36, the extraction plane 32 becomes parallel to the total reflection plane 22 and comes into intimate contact with the total reflection plane 22. Thus, the optical switching device 1 in the present example comes into the on-state in which incident light is modulated and output as output light. [0198] In the optical switching device 1 in the present example and also in those according to the previous embodiments, as described above, the switching part 30 can be moved at a high speed from the on-position to the off-position and from the off-position to the on-position within a fluid ambient such as air or inert gas thereby achieving a spatial optical modulation device capable of responding at a high speed with low power consumption without needing a vacuum ambient. [0199]FIGS. 39 and 40 illustrate an example in which the electrode 60 on the substrate is divided into left and right portions. FIG. 41 is a timing chart representing the process of supplying voltages to the electrodes 60 a and 60 b in the left and right regions wherein the voltages are varied in magnitude with time. In the present example of the optical switching device 1, as shown in FIG. 30(a), the electrode 60 is divided into electrically isolated electrodes 60 a and 46 b in the left and right regions 12 a and 12 b left and right to the geometric center line 14, so that electrostatic forces generated in the regions 12 a and 121 b can be controlled by separately controlling electric power supplied from the power supply 61 to the respective electrodes. To this end, the power supply 61 includes a power supply unit 61 a connected to the left electrode 60 a and a power supply unit 61 b connected to the right electrode 60 b. Furthermore, there is provided a control unit 61 c for controlling the voltages supplied from the respective power supply units 61 a and 61 b to the electrodes 60 a and 60 b. Also in the present optical switching device 1 as in the previous example, when no electric power is supplied to the electrodes 62 and 60, the switching part 30 is maintained in the off-state at the first position by the elastic force provided by the yokes 50 and 52. [0200] At time t 41, a voltage Vb 1 is supplied from the power supply unit 61 a to the left electrode 60 a thereby supplying electric power thereto, and a voltage V 2 is supplied from the power supply unit 61 b to the right electrode 60 b thereby supplying electric power thereto, wherein the voltage V 1 supplied to the left electrode 60 a is set to a value greater than the voltage V 2 supplied to the right electrode 60 b so that a greater electrostatic force is exerted on the switching part 30 in the left region 12 a than in the right region 12 b. As a result, the driving force becomes asymmetric in the left-to-right direction about the center of gravitation 14 b of the switching part 30. Thus, the switching part 30 starts to tilt and move as shown in FIG. 39(b). That is, the extraction plane 32 separates starting from the left region 12 a and thus it tilts. Thus, also in the present optical switching device 1 as in the previous embodiments, the switching part 30 can be moved smoothly without encountering a large air resistance. [0201] Furthermore, at time t 42, substantially equal voltages V 3 are supplied to the left and right electrodes 60 a and 60 b from the power supply unit 61 a and 61 b under the control of the control unit 61 c, thereby moving the switching part 30 to the second position while maintaining the properly tilted angle, as shown in FIG. 40(a). When the electrode 62 collides with a stopper 65 e, the switching part 30 stops at the second position as shown in FIG. 40(b). In this final stage of the movement, the switching part 30 comes into a parallel state from the tilted state in a similar manner as in the previous embodiments, and air is quickly removed from the space and the switching part 30 finally comes to rest. In the present optical switching device 1, the electrodes 60 a and 60 b on the substrate are formed in a non-flat shape having a protruding part 65 e serving as the stopper thereby preventing the electrode 62 of the switching part from coming into intimate contact with the electrode 60 a or 60 b on the substrate. [0202] When the switching part 30 is moved from the second position to the first position, the electric power to the right base electrode 60 b is turned off at time t 43 and the electric power to the left base electrode 60 a may be gradually reduced as shown in FIG. 41 so that the right part of the switching part 30 in the region 12 b immediately starts to move by means of the elastic force provided by the yoke 52 whereas the electrostatic force generated between the base electrode 60 a and the electrode 62 and exerted on the left part of the switching part 30 in the region 12 a gradually decreases. Therefore, also when the switching part 30 starts to move from the second position, the switching part 30 is first tilted to a proper angle, and then it is moved toward the first position while maintaining the tilted state. Thus, also in the movement from the second position to the first position, a reduction in air resistance is achieved and the switching part 30 can be moved at a high speed. [0203] The optical switching devices 1 described above operate as a spatial optical modulation device capable of turning on and off incident light. A single optical switching device 1 may be utilized in a separate fashion, or a plurality of optical switching devices may be disposed in an array fashion so as to obtain various devices such as an image display device for use in various applications such as an optical communication, optical operation, optical recording, etc. By tilting the switching part from the orientation in the on-state at the start of the moving process, it is possible to greatly reduce the resistance of the fluid present around the switching part. This allows the spatial optical modulation device according to the present invention to be used in air or an inert gas ambient such as a nitrogen ambient. Thus, the spatial optical modulation device can operate at a high speed and respond at a high speed in a highly reliable fashion. The reduction in the fluid resistance allows a reduction in electric power required to drive the spatial optical modulation device. [0204] The method of controlling the attitude disclosed herein may be applied not only to optical switching devices using an evanescent wave but also to various types of spatial optical modulation devices in which incident light is modulated by moving a flat plane element corresponding to the extraction plane of the switching part so as to vary the interference characteristics, or by varying the polarization direction or the phase of reflected light. [0205] Although in the above-described embodiments, the yokes formed of the thin film are used as the elastic member, an elastic member in another form such as a coil spring may also be employed. Furthermore, also in the above-described embodiments, the driving part is realized in the form of a combination of the supporting member (yoke or spring member) for the elastic support and the electrostatic driving means. A piezoelectric device may also be employed as a driving source for driving the switching part. FIG. 42 illustrates an example in which a piezoelectric element 99 is employed. In this optical switching device 1, instead of a microprism, a reflective type light outputting member 36 including a plurality of reflecting elements is employed as the optical switching part 30. In this optical switching device 1, therefore, evanescent light captured by the extraction plane 32 in the on-state is scattered by the light outputting member 36 at proper angles toward the light guide 20. This makes it possible to form an image which can be seen from a wide range of viewing angles. [0206] In the present optical switching device 1, the driving source for driving the switching part 30 uses electrostriction produced by the piezoelectric element 99 instead of electrostatic force. The piezoelectric element 99 employed in the present example is of the bimorph type including two layers which have different polarization directions and which are disposed in the form of a two-layer structure. When electric power is applied to the piezoelectric element 99, it stretches into a straight form from a bent state, and thus the yoke or the spring member 50 is drawn by the piezoelectric element 99. As a result, the optical switching device 1 is turned off. If the electric power is turned off, the piezoelectric element 99 goes into the bent state in which an elastic force is generated by the piezoelectric element 99. In this state, the optical switching part 30 is urged by the elastic force provided by the piezoelectric element 99 and the yoke 50 toward the light guide 20. Thus, an optical switching device with a high contrast can be obtained. [0207] Because the optical switching device 1 according to the present invention is formed in the multilayer structure consisting of the layer of the light guide 20, the layer of the switching part 30, and the layer of the driving part 40, it is possible to flexibly combine an optical switching part 30 and a driving part 40 according to any of embodiment disclosed above so as to realize an optical switching device suitable for use in a particular application. The application of the optical switching device according to the present invention is not limited to image display devices but may be applied to a wide variety of applications such as a line-shaped light valve for use in an optical printer, an optical spatial modulator for use in a three-dimensional hologram memory, and applications in which conventional optical switching devices using a liquid crystal are currently employed. In particular, the optical switching device according to the present invention is suitable for use in devices which require an optical switching device capable of operating at a higher speed and capable of outputting a higher intensity of light than can be achieved by conventional optical switches using a liquid crystal. The optical switching device according to the present invention may be produced by a microfabrication technique into a form smaller in size and thickness and higher in integration density than can be achieved in the conventional optical switching devices using a liquid crystal. [0208] In the optical switching device according to the present invention, as described above, the extraction plane is brought into contact with the light guide having the total reflection plane capable of totally reflecting light thereby transmitting the light, so that evanescent light leaking through the total reflection plane is captured thereby forming an image. The light guide, the reflective type optical switching part, and the driving part are laminated in this order so as to realize an optical switching device capable of reflecting the extracted light by the optical switching part in a substantially vertical direction toward the light guide thereby outputting high intensity light without creating a loss in the driving part. The employment of the multilayer structure allows the respective layers of the light guide, the optical switching part, and the driving part to be separately designed into optimum forms. Furthermore, layers having various different functions and structures may be arbitrarily combined into the multilayer structure. In particular, by positioning the optical switching part the driving part and forming a space in which the elastic spring member is disposed, it becomes possible to form the light guide into a flat shape and it also becomes possible to increase the area of the extraction plane of the optical switching part. This makes it possible to provide a high-brightness and high-contrast optical switching device with a large aperture ratio. Using such an optical switching device according to the present invention, it is possible to provide an image display device capable of forming a high-quality image. [0209] Furthermore, by applying a bias voltage with a value within a proper range which allows the switching part to be held at the on-position, the driving voltage can be reduced without causing degradation in the characteristics of the switching part. Furthermore, by forming a two pairs of electrodes for creating electrostatic force, the driving voltage can be further reduced by several-tenths or one order of magnitude. This allows the switching part to be moved at a high speed. Thus, it is possible to provide a spatial optical modulation device which can be driven by a low voltage and which can respond in a short time, that is, can respond at a high speed. [0210] Such a great reduction in the driving voltage allows the switching device or the image display device to be directly driven by a semiconductor controlling device. [0211] As a result, the cost of the switching device and the image display device can be greatly reduced. Furthermore, the reduction in the driving voltage allows a great reduction in the power consumption of the switching device and the image display device. Therefore, it becomes possible to employ a power source having a limitation in output power such as a battery to drive the high-speed switching device using an evanescent wave and the image display device. Thus, the optical switching device capable of extracting an evanescent wave by moving the switching part thereby modulating light according to the present invention is very useful in various applications. [0212] Furthermore, by tilting the orientation of the extraction plane or the flat plane element at the first position from the first direction, it is possible to reduce the resistance of air or fluid such as an inert gas present around the switching part. [0213] This allows a reduction in the force required to move the switching part against the resistance. Therefore, it becomes possible to move the switching part at a still higher speed using electrostatic force or the like. Thus, it is possible to provide a spatial optical modulation device capable of responding at a high speed. The reduction in the force required to move the switching part against the resistance also allows a reduction in the power consumption. As a result, it is possible to provide an optical switching device capable of responding at a high speed under common environmental conditions such as in air. Industrial Applicability [0214] The optical switching device according to the present invention is capable of operating at a high speed and providing a high contrast. This allows the optical switching device according to the present invention to be used in a wide variety of applications such as an image display device, a line-shaped light valve for use in an optical printer, an optical spatial modulator for use in a three-dimensional hologram memory, etc. The optical switching device according to the present invention is not only applicable to applications in which conventional optical switching devices using a liquid crystal are currently employed, but also advantageously applicable in particular to devices which require a higher speed and a higher intensity of light than can be achieved by conventional optical switches using a liquid crystal. Referenced byCiting PatentFiling datePublication dateApplicantTitleUS6542653 *Mar 12, 2001Apr 1, 2003Integrated Micromachines, Inc.Latching mechanism for optical switchesUS7465104 *Apr 28, 2004Dec 16, 2008Sharp Kabushiki KaishaDisplayUS7880565Sep 28, 2009Feb 1, 2011Kolo Technologies, Inc.Micro-electro-mechanical transducer having a surface plateUS8004373Oct 6, 2009Aug 23, 2011Kolo Technologies, Inc.MEMS ultrasonic device having a PZT and cMUTUS8008105May 18, 2006Aug 30, 2011Kolo Technologies, Inc.Methods for fabricating micro-electro-mechanical devicesUS8018301Jan 31, 2011Sep 13, 2011Kolo Technologies, Inc.Micro-electro-mechanical transducer having a surface plateUS8105941May 18, 2006Jan 31, 2012Kolo Technologies, Inc.Through-wafer interconnectionUS8120229May 18, 2006Feb 21, 2012Kolo Technologies, Inc.Middle spring supported micro-electro-mechanical transducersUS8152318Jun 11, 2009Apr 10, 2012Rambus International Ltd.Optical system for a light emitting diode with collection, conduction, phosphor directing, and output meansUS8152352Jan 2, 2009Apr 10, 2012Rambus International Ltd.Optic system for light guide with controlled outputUS8247945May 18, 2006Aug 21, 2012Kolo Technologies, Inc.Micro-electro-mechanical transducersUS8272770Jan 2, 2009Sep 25, 2012Rambus International Ltd.TIR switched flat panel displayUS8292445Jan 27, 2012Oct 23, 2012Rambus Inc.Optical system for a light emitting diode with collection, conduction, phosphor directing, and output meansUS8297818Jun 11, 2009Oct 30, 2012Rambus International Ltd.Optical system with reflectors and light pipesUS20100221846 *Oct 7, 2008Sep 2, 2010Nxp B.V.Sensor, a sensor array, and a method of operating a sensorWO2004107015A1 *May 27, 2004Dec 9, 2004Anthonie H BergmanDisplay device with multiple channel wave guideWO2006123300A2 *May 18, 2006Nov 23, 2006Yongli HuangMicro-electro-mechanical transducersWO2006123301A2 *May 18, 2006Nov 23, 2006Yongli HuangMicro-electro-mechanical transducersWO2010077363A1 *Dec 31, 2009Jul 8, 2010Richardson, Brian EdwardTotal internal reflection switched flat panel display* Cited by examinerClassifications U.S. Classification385/16International ClassificationG02B26/08, G09G3/34Cooperative ClassificationY10S385/901, G02B26/0816, G09G3/3473, G09G2300/06, G09G2310/06European ClassificationG02B26/08M, G09G3/34E10Legal EventsDateCodeEventDescriptionJan 29, 2010FPAYFee paymentYear of fee payment: 8Jan 27, 2006FPAYFee paymentYear of fee payment: 4RotateOriginal ImageGoogle Home - Sitemap - USPTO Bulk Downloads - Privacy Policy - Terms of Service - About Google Patents - Send FeedbackData provided by IFI CLAIMS Patent Services©2012 Google