Interferometric modulation of radiation

• US 6,680,792 B2
• Filed: 10/10/2001
• Issued: 01/20/2004
• Est. Priority Date: 05/05/1994
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Iridigm Display Corporation (Qualcomm, Inc.)
• Inventors: Miles, Mark W.
• Primary Examiner(s): LESTER, EVELYN A
• Application Number:
  US09/974,544
• Publication Number:
  US 20020024711A1
• Time in Patent Office: 832 Days
• Field of Search: 359/578, 359/582, 359/584, 359/586, 359/589, 359/846, 359/848, 359/198, 359/223, 359/290-292, 359/298, 345/85, 345/108, 345/598-600
• US Class Current: 359/291
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 2027/0112 comprising device for genereting colour display
• CPC Class Codes: G02B 2027/0118 comprising devices for improving the contrast of the display / brillance control visibility
• CPC Class Codes: G02B 26/001 based on interference in an adjustable optical cavity interference filters G02B5/28; devices or arrangements using multiple reflections in spectrometry or monochromators G01J3/26
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G02B 26/085 the reflecting means being moved or deformed by electromagnetic means
• CPC Class Codes: G02B 26/0858 the reflecting means being moved or deformed by piezoelectric means
• CPC Class Codes: G02B 27/01 Head-up displays
• CPC Class Codes: G02B 27/0101 characterised by optical features G02B27/0172 takes precedence
• CPC Class Codes: G02B 27/017 Head mounted
• CPC Class Codes: G02B 6/12 of the integrated circuit kind electric integrated circuits H01L27/00
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence
• CPC Class Codes: G02F 1/216 using liquid crystals, e.g. liquid crystal Fabry-Perot filters
• CPC Class Codes: G02F 2203/03 scattering
• CPC Class Codes: G09G 2300/0452 Details of colour pixel setup, e.g. pixel composed of a red, a blue and two green components
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3466 : based on interferometric effect

Abstract

An Interferometric Modulator (IMod) is a microelectromechanical device for modulating light using interference. The colors of these devices may be determined in a spatial fashion, and their inherent color shift may be compensated for using several optical compensation mechanisms. Brightness, addressing, and driving of IMods may be accomplished in a variety of ways with appropriate packaging, and peripheral electronics which can be attached and/or fabricated using one of many techniques. The devices may be used in both embedded and directly perceived applications, the latter providing multiple viewing modes as well as a multitude of product concepts ranging in size from microscopic to architectural in scope.

Claims

1. A modulator of light comprising:

a substrate;

a plurality of modulation elements formed on the substrate each modulation element defining an interference cavity for causing interference modulation of the light to produce a color condition when in a quiescent state, wherein the modulation element is of at least two types each having a different color condition when in the quiescent state, which color condition is a result of a spatial configuration of the modulation element.

2. The modulation element of claim 1, wherein each modulation element further comprises a mirror located within the interference cavity, and a supporting structure holding the mirror, wherein the spatial configuration comprises a configuration of the supporting structure.

3. The modulator of claim 1, wherein each modulation element comprises a mirror located in the interference cavity, wherein the spatial configuration comprises a pattern formed in the mirror.

4. The modulator of claim 1, wherein each modulation element comprises a mirror located in the interference cavity, and a supporting structure holding the mirror, wherein the supporting structure is coupled to a rear surface of the mirror.

5. An interference modulation device, comprising:

a plurality of interference modulation elements fabricated on a substrate, each interference modulation element comprising a primary mirror and a secondary mirror which cooperate to interferometrically modulate incident light to produce a response in a quiescent state which response is determined by a spacing between the mirrors, wherein the interference modulation elements are of at least two types, each producing a different response in the quiescent state; and

a driving mechanism to apply a bias voltage to each interference modulation element to cause the mirrors to be spaced apart the quiescent state, wherein each type of interference modulation element has a configuration that allows it to move to its quiescent state under influence of the same bias voltage.

6. The interference modulation device of claim 5, wherein the configuration comprises support arms supporting the secondary mirror and being shaped and dimensioned to allow the secondary mirror for each type of interference modulation element to be displaced by an amount under influence of the same bias voltage to cause the secondary mirror to be spaced from the primary mirror as in the quiescent state.

7. The interference modulation device of claim 6, wherein the configuration includes patterns formed in at least one of the mirrors so that each type of interference modulation element can be driven to the quiescent state by the same bias voltage.

8. A method for fabricating a modulation device, the method comprising:

fabricating a plurality of interference modulation elements on a substrate, each interference modulation element comprising a primary mirror and a secondary mirror which cooperate to interferometrically modulate incident light to produce a response when in a quiescent state, which response is determined by a size of the a gap between the mirrors, the interference modulation elements being of at least two types, each having a different size gap and hence response when in the quiescent state, the fabricating including;

depositing a uniform thickness sacrificial spacer material to space the primary and secondary mirrors during the fabrication process;

altering a spatial configuration of each type of interference modulation element so that under influence of a uniform bias voltage, the secondary mirror of each type of interference modulation element is displaced to a position corresponding to the quiescent state for that type of interference modulation element; and

removing the sacrificial spacer material.

9. The method of claim 8, wherein the altering comprises altering a mechanical property of support arms supporting the secondary mirror in each interference modulation element so as to change a spring constant thereof.

10. The method of claim 8, wherein the altering comprises patterning at least one of the primary and secondary mirrors so as to alter its optical properties.