Methods for visually inspecting interferometric modulators for defects

• US 8,385,714 B2
• Filed: 06/16/2011
• Issued: 02/26/2013
• Est. Priority Date: 09/27/2004
• Status: Expired due to Fees

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Gally, Brian J, Cummings, William J
• Primary Examiner(s): Connelly, Michelle R
• Application Number:
  US13/162,159
• Publication Number:
  US 20110242529A1
• Time in Patent Office: 621 Days
• Field of Search: None
• US Class Current: 385/147
• 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: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

A method is provided for visual inspection of an array of interferometric modulators in various driven states. This method may include driving multiple columns or rows of interferometric modulators via a single test pad or test lead, such as test pad, and then observing the array for discrepancies between the expected optical output and the actual optical output of the array. This method may particularly include, for example, driving a set of non-adjacent rows or columns to a state different from the intervening rows or columns and then observing the optical output of the array.

Claims

1. A method of testing an array of interferometric modulators, the method comprising:

applying a first signal at least partly contemporaneously to a first plurality of non-adjacent columns of interferometric modulators, the first signal comprising at least one hold time signal portion of a voltage which is less than an actuation voltage and greater than a release voltage and at least one pulse having a voltage greater than the actuation voltage or less than the release voltage; and

inspecting said array of interferometric modulators to identify defects in said array, wherein said inspecting is performed during the hold time signal portion.

2. The method of claim 1, additionally comprising applying a second signal at least partly contemporaneously to a second plurality of columns of interferometric modulators in the array, wherein the second plurality of columns comprises every column in said array of interferometric modulators except for said first plurality of columns.

3. The method of claim 2, wherein the second signal comprises at least one hold time signal portion of a voltage which is less than an actuation voltage and greater than a release voltage and at least one pulse having a voltage greater than the actuation voltage or less than the release voltage.

4. The method of claim 2, wherein said first signal is substantially identical to said second signal.

5. The method of claim 2, additionally comprising applying a third signal at least partly contemporaneously to all columns of interferometric modulators in said array to place all modulators in said array in an unactuated state, wherein said third signal is applied before said first and second signals.

6. The method of claim 1, wherein a diffuser layer is placed between an observer and said array prior to inspecting said array of interferometric modulators.

7. The method of claim 1, wherein inspecting the array of interferometric modulators comprises identifying the locations of any visible defects.

8. A method of testing an array of interferometric modulators, the method comprising:

applying a first waveform at least partly contemporaneously to each of a first plurality of non-adjacent rows of interferometric modulators;

applying a second waveform at least partly contemporaneously to each of a second plurality of non-adjacent rows of interferometric modulators;

applying a third waveform at least partly contemporaneously to each of a first plurality of non-adjacent columns of interferometric modulators;

applying a fourth waveform at least partly contemporaneously to each of a second plurality of non-adjacent columns of interferometric modulators; and

inspecting said array of interferometric modulators to identify defects in the array,

wherein at least one of the first, second, third, or fourth waveforms comprises at least one hold time signal portion of a voltage which is less than an actuation voltage and greater than a release voltage and at least one pulse having a voltage greater than the actuation voltage or less than the release voltage, and

wherein the sum of the first and third waveforms or the sum of the second and fourth waveforms causes an interferometric modulator to actuate.

9. The method of claim 8, wherein said first and second pluralities of non-adjacent columns comprise every column in the array, and wherein said first and second pluralities of non-adjacent rows comprise every row in the array.

10. The method of claim 8, wherein said interferometric modulators in said first plurality of non-adjacent columns comprise interferometric modulators that are larger than said interferometric modulators in said second plurality of non-adjacent columns.

11. The method of claim 10, wherein the interferometric modulators in said first plurality of non-adjacent columns comprise interferometric modulators which have a larger viewable area than the interferometric modulator elements in said second plurality of non-adjacent columns.

12. The method of claim 8, additionally comprising applying a fifth waveform at least partly contemporaneously to each of a third plurality of non-adjacent columns of interferometric modulators.

13. The method of claim 12, wherein each of the modulators in the third plurality of columns of interferometric modulators are configured to reflect light of about the same color.

14. The method of claim 12, wherein said first, second, and third pluralities of non-adjacent columns comprise every column in the array, and wherein said first and second pluralities of non-adjacent rows comprise every row in the array.

15. The method of claim 12, wherein each of the modulators of the first plurality of non-adjacent columns are configured to reflect light of a first color, each of the modulators of the second plurality of non-adjacent columns are configured to reflect light of a second color, and the third plurality of non-adjacent columns are configured to reflect light of a third color.

16. The method of claim 8, additionally comprising placing a diffuser adjacent the array of interferometric modulators.