Methods for visually inspecting interferometric modulators for defects

• US 7,978,953 B2
• Filed: 08/15/2008
• Issued: 07/12/2011
• 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: Cummings, William J, Gally, Brian J
• Primary Examiner(s): CONNELLY, MICHELLE R
• Application Number:
  US12/192,817
• Publication Number:
  US 20080303531A1
• Time in Patent Office: 1,061 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 inspecting an array of interferometric modulators, comprising:

driving each modulator in the array of interferometric modulators to a known first state;

applying a pulse to a subset of columns of the array of interferometric modulators to drive the interferometric modulators within the columns of the array from the known first state to a second state, wherein said second state is the opposite of said first state; and

inspecting said array of interferometric modulators to identify defects in the array after application of the pulse.

2. The method of claim 1, wherein the known first state is a bright state, and wherein the second state is a dark state.

3. The method of claim 1, additionally comprising:

driving each modulator in the array back to said known first state; and

driving a second subset of columns of interferometric modulators within the array from said known first state to said second state.

4. The method of claim 3, additionally comprising:

driving each modulator in the array back to said known first state; and

driving a third subset of columns of interferometric modulators within the array from said known first state to said second state.

5. The method of claim 1, additionally comprising:

driving each modulator in the array to a known third state; and

driving a subset of rows of interferometric modulators within the array to a fourth state, wherein said fourth state is the opposite of said third state.

6. The method of claim 5, wherein said known third state is a bright state, and wherein said fourth state is a dark state.

7. The method of claim 5, additionally comprising:

driving each modulator in the array back to said known third state; and

driving a second subset of rows of interferometric modulators within the array to said known fourth state.

8. The method of claim 1, additionally comprising:

driving each of the modulators in the array to a known fifth state; and

driving each of the modulators in the array to a sixth state, wherein the sixth state is the opposite of the known fifth state.

9. The method of claim 8, wherein the known fifth state is a bright state and wherein the sixth state is a dark state.

10. The method of claim 1, wherein the array is formed on a substrate having a viewer side and a process side, the array being formed on the process side of the substrate.

11. The method of claim 10, additionally comprising placing a diffuser layer adjacent the viewer side of the substrate.

12. The method of claim 10, additionally comprising placing the substrate within a probe mount prior to driving the array.

13. The method of claim 1, additionally comprising determining an intra-column open based on the identified defects.

14. The method of claim 1, additionally comprising determining a row to column short based on the identified defects.

15. The method of claim 1, wherein the subset of columns comprises two non-adjacent columns but does not comprise a particular column between the non-adjacent columns.

16. A system for inspecting an array of interferometric modulators, comprising:

an array driver configured to drive each modulator in the array of interferometric modulators to a known first state and to apply a pulse to a subset of columns of the array of interferometric modulators to drive the interferometric modulators within the columns of the array from the known first state to a second state, wherein said second state is the opposite of said first state;

a camera configured to inspect said array of interferometric modulators; and

a processor configured to identify defects in the array after application of the pulse based on the inspection.

17. A system for inspecting an array of interferometric modulators, comprising:

means for driving each modulator in the array of interferometric modulators to a known first state;

means for applying a pulse to a subset of columns of the array of interferometric modulators to drive the interferometric modulators within the columns of the array from the known first state to a second state, wherein said second state is the opposite of said first state; and

means for inspecting said array of interferometric modulators to identify defects in the array after application of the pulse.