Visible spectrum modulator arrays

• US 7,126,738 B2
• Filed: 02/25/2002
• Issued: 10/24/2006
• Est. Priority Date: 05/01/1995
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: IDC, LLC
• Inventors: Miles, Mark W.
• Primary Examiner(s): MAI, HUY KIM
• Application Number:
  US10/082,397
• Publication Number:
  US 20030072070A1
• Time in Patent Office: 1,702 Days
• Field of Search: 359245-247, 359/249, 359315-317
• US Class Current: 359/245
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• 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 26/08 for controlling the direction of light in light guides G02B6/35
• CPC Class Codes: G02F 1/19 based on variable-reflection or variable-refraction elements not provided for in groups G02F1/015 - G02F1/169
• CPC Class Codes: G09G 2300/0456 with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/22 using controlled light sources
• CPC Class Codes: G09G 3/34 by control of light from an independent source
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Light in the visible spectrum is modulated using an array of modulation elements, and control circuitry connected to the array for controlling each of the modulation elements independently, each of the modulation elements having a surface which is caused to exhibit a predetermined impedance characteristic to particular frequencies of light. The amplitude of light delivered by each of the modulation elements is controlled independently by pulse code modulation. Each modulation element has a deformable portion held under tensile stress, and the control circuitry controls the deformation of the deformable portion. Each deformable element has a deformation mechanism and an optical portion, the deformation mechanism and the optical portion independently imparting to the element respectively a controlled deformation characteristic and a controlled modulation characteristic. The deformable modulation element may be a non-metal. The elements are made by forming a sandwich of two layers and a sacrificial layer between them, the sacrificial layer having a thickness related to the final cavity dimension, and using chemical (e.g., water) or a plasma based etch process to remove the sacrificial layer.

Claims

1. An interferometric modulator comprising a sandwich of two or more layers, at least one of to layers comprising two or more films, the stress of each film being arranged so that the overall stress of the layer ranges from zero to tensile in magnitude;

wherein the layers of the sandwich are movable relative to each other.

2. The interferometric modulator of claim 1 wherein at least one of the layers comprises a support membrane.

3. The interferometric modulator of claim 2 wherein the support membrane has a tensile residual stress.

4. The interferometric modulator of claim 1 wherein the overall stress of at least one of the layers is zero.

5. The interferometric modulator of claim 1 wherein the overall stress of at least one of to layers is tensile.

6. The interferometric modulator of claim 1 wherein at least one of the layers comprises a mirror.

7. The interferometric modulator of claim 1 wherein at least one of the films comprises a metal.

8. The interferometric modulator of claim 7 wherein the metal comprises aluminum or silver.

9. The interferometric modulator of claim 1 wherein at least one of the films comprises an insulator.

10. The interferometric modulator of claim 9 wherein the insulator comprises silicon oxide or silicon nitride.

11. A method for making an interferometric modulator, comprising:

forming a sandwich of two or more layers, at least one of the layers comprising two or more films;

arranging the stress of each film so that the overall stress of the layer ranges from zero to tensile in magnitude; and

configuring the layers of the sandwich to be movable relative to each other.

12. The method of claim 11 wherein at least one of the layers comprises a support membrane.

13. The method of claim 12 comprising arranging the stress of the support membrane to be a tensile residual stress.

14. The method of claim 11 comprising arranging the stress of each film so that the overall stress of at least one of the layers is zero.

15. The method of claim 11 comprising arranging the stress of each film so that the overall stress of at least one of the layers is tensile.

16. The method of claim 11 wherein at least one of the layers comprises a mirror.

17. The method of claim 11 wherein at least one of the films comprises a metal.

18. The method of claim 17 wherein the metal comprises aluminum or silver.

19. The method of claim 11 wherein at least one of the films comprises an insulator.

20. The method of claim 19 wherein the insulator comprises silicon oxide or silicon nitride.