SENSING TO DETERMINE PIXEL STATE IN A PASSIVELY ADDRESSED DISPLAY ARRAY

• US 20090201242A1
• Filed: 02/03/2009
• Published: 08/13/2009
• Est. Priority Date: 02/11/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Govil, Alok
• Granted Patent: US 8,466,858 B2
• Time in Patent Office: Days
• US Class Current: 345/98
• CPC Class Codes: G02F 1/133514 Colour filters
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2320/08 Arrangements within a display terminal for setting, manually or automatically, display parameters of the display terminal
• 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 3/346 based on modulation of the reflection angle, e.g. micromirrors micromirrors devices per se G02B26/0833
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

Devices and methods for determining an operational state of a selected display device in an array of display devices. One method includes determining the operational state of a particular display device in the array by measuring an electrical characteristic of a plurality of the display devices, and determining the operational state based at least in part on the three measurements. In some embodiments, the electrical characteristic is capacitance, in other embodiments impedance can be the measured electrical characteristic. Such methods can be applied to IMOD displays and other displays, including LCD displays.

Claims

1. In an array of electrical devices formed in rows and columns, the array coupled to a plurality of row electrodes and a plurality of column electrodes, a method of determining an electrical characteristic of one or more selected electrical devices, each selected electrical device located in a selected row of the array and in a selected column of the array, the method comprising:

measuring or predetermining a first value of the electrical characteristic between selected row electrodes and said plurality of column electrodes, said plurality of column electrodes being driven to a common voltage and at least a portion of non-selected row electrodes being configured in a floating state for the first value measurement;

measuring or predetermining a second value of the electrical characteristic between the selected column electrodes and said plurality of row electrodes, said plurality of row electrodes being driven to a common voltage and at least a portion of non-selected column electrodes being configured in a floating state for the second value measurement;

measuring a third value of an electrical characteristic between selected the row electrodes and the selected column electrodes, the non-selected column and row electrodes being configured in a floating state for the third value measurement; and

determining a resulting electrical characteristic or operational state of the one or more selected electrical devices based at least in part on the first and second measured or predetermined values, and the third measured values of the electrical characteristic.

2. The method of claim 1, wherein the array of electrical devices comprises microelectromechanical electrical devices.

3. The method of claim 2, wherein the microelectromechanical devices comprise at least one interferometric modulator.

4. The method of claim 1, wherein the array of electrical devices comprises liquid crystal display (LCD) devices.

5. The method of claim 1, wherein each of the selected electrical devices are coupled to a selected row electrode and a selected column electrode where they intersect.

6. The method of claim 1, wherein said plurality of row electrodes are driven to a common voltage by commonly connecting the plurality of row electrodes.

7. The method of claim 1, wherein said plurality of column electrodes are driven to a common voltage by commonly connecting the plurality of column electrodes.

8. The method of claim 1, wherein the electrical characteristic comprises capacitance.

9. The method of claim 8, wherein the electrical characteristic is capacitance, and wherein determining capacitance (C_selected—

<sub>display—

device</sub>) of the selected one or more selected electrical devices comprises using the first value (C<sub>first—

value</sub>), the second value (C<sub>second—

value</sub>), and the third value (C<sub>third—

value</sub>) in substantially the following relationship;

$C_{\mathrm{selected}<br><br>\_<br><br>\mathrm{display}<br><br>\_<br><br>\mathrm{device}}=\frac{1}{2}<br><br>\left(C_{s<br><br>\mathrm{econd}<br><br>\_<br><br>\mathrm{value}}+C_{\mathrm{third}<br><br>\_<br><br>\mathrm{value}}-\frac{C_{s<br><br>\mathrm{econd}<br><br>\_<br><br>\mathrm{value}}<br><br>C_{\mathrm{third}<br><br>\_<br><br>\mathrm{value}}}{C_{\mathrm{first}<br><br>\_<br><br>\mathrm{value}}}\right)$

10. The method of claim 1, wherein the electrical characteristic comprises impedance.

11. The method of claim 1, wherein determining an operational state of the one or more selected electrical device comprises comparing the electrical characteristic of said one or more selected electrical devices and a threshold value.

12. A method of determining an operational state of a selected electrical device in a selected row and a selected column of an array, the array comprising a plurality of electrical devices each coupled to a row electrode and a column electrode of a plurality of row electrodes and a plurality of column electrodes of the display, the method comprising:

measuring or predetermining capacitance between the selected row electrode and a plurality of commonly connected column electrodes;

measuring or predetermining capacitance between the selected column electrode and a plurality of commonly connected row electrodes;

measuring capacitance between the selected row electrode and the selected column electrode; and

determining a state of the selected electrical device based at least in part on the measured or predetermined capacitances.

13. The method of claim 12, wherein the array of electrical devices comprises interferometric modulators.

14. A method of estimating capacitance of one or more selected electrical devices in an array having a plurality of rows of electrical devices and a plurality of columns of electrical devices, the method comprising:

measuring or predetermining capacitance C_row between row electrodes coupled to the selected electrical devices and a plurality of column electrodes coupled to the plurality of columns, the plurality of column electrodes driven to a common voltage;

measuring or predetermining capacitance C_column between column electrodes coupled to the selected electrical devices and a plurality of row electrodes coupled plurality of rows, the plurality of row electrodes driven to a common voltage;

measuring capacitance C_effective between the row electrodes and the column electrode coupled to the selected electrical devices; and

estimating capacitance C_P of the selected electrical devices based at least in part on the measured or predetermined capacitances C_row, C_column, and C_column.

15. The method of claim 14, wherein estimating capacitance C_P comprises using the capacitance C_row, the capacitance C_column, and the capacitance C_effective in substantially the following relationship:

$C_p=\frac{1}{2}<br><br>\left(C_{\mathrm{row}}+C_{\mathrm{column}}-\frac{C_{\mathrm{row}}<br><br>C_{\mathrm{column}}}{C_{\mathrm{effective}}}\right)$

16. The method of claim 14, wherein the plurality of row electrodes are driven to a common voltage by commonly connecting the plurality of row electrodes.

17. The method of claim 14, wherein the plurality of column electrodes are driven to a common voltage by commonly connecting the plurality of column electrodes.

18. The method of claim 14, further comprising estimating the operational state of the selected electrical devices by comparing the capacitance of the selected electrical devices and a threshold value.

19. A device for estimating capacitance of one or more selected electrical devices in an array of electrical devices, comprising:

at least one driving circuit;

an array of electrical devices, each electrical device being coupled to one of a plurality of first electrodes and one of a plurality of second electrodes;

measuring circuitry configured to

measure capacitance C_row between first electrodes coupled to the selected electrical devices and a plurality of second electrodes coupled to the array, the second electrodes driven to a common voltage potential,

measure capacitance C_column between second electrodes coupled to the selected electrical devices and a plurality of first electrodes coupled to the array, the first electrodes driven to a common voltage potential, and

measure capacitance C_effective between the first electrodes and the second electrodes coupled to the selected electrical devices; and

capacitance estimating circuitry configured to estimate capacitance C_p of the selected electrical device based at least in part on the measured capacitances.

20. The device of claim 19, wherein the capacitance estimating circuitry is configured to estimate the capacitance C_p using the capacitance C_row, the capacitance C_column, and the capacitance C_effective in substantially the following relationship:

$C_p=\frac{1}{2}<br><br>\left(C_{\mathrm{row}}+C_{\mathrm{column}}-\frac{C_{\mathrm{row}}<br><br>C_{\mathrm{column}}}{C_{\mathrm{effective}}}\right)$

21. The device of claim 19, further comprising:

a display;

a processor that is configured to communicate with the display, the processor being configured to process image data; and

a memory device that is configured to communicate with the processor.

22. The device of claim 21, further comprising a driver circuit configured to send at least one signal to the display.

23. The device of claim 22, further comprising a controller configured to send at least a portion of the image data to the driver circuit.

24. The device of claim 21, further comprising an image source module configured to send the image data to the processor.

25. The device of claim 24, wherein the image source module comprises at least one of a receiver, transceiver, and transmitter.

26. The device of claim 21, further comprising an input device configured to receive input data and to communicate the input data to the processor.

27. A device for estimating capacitance of one or more selected electrical devices in an array having rows and columns of electrical devices, comprising:

means for displaying data on a plurality of electrical devices, the plurality of electrical devices formed in rows and columns and coupled to a series of row electrodes and a series of column electrodes;

means for driving the data displaying means;

means for measuring or predetermining capacitance C_row between row electrodes coupled to one or more selected electrical devices and a plurality of column electrodes coupled to the displaying means and driven to a common voltage potential, measuring or predetermining capacitance C_column between column electrodes coupled to the one or more selected electrical devices and a plurality of row electrodes coupled to the displaying means and driven to a common voltage potential, and measuring capacitance C_effective between the row electrodes and the column electrodes coupled to the one or more selected electrical devices, and providing signals and indicative of the capacitance measurements; and

means for estimating capacitance C_p of the one or more selected electrical devices based at least on signals received from the measuring means indicative of the capacitance measurements.

28. The device of claim 27, wherein said measuring or predetermining means comprises capacitance measuring circuitry, and wherein said estimating means comprises pixel capacitance compiling logic.

29. The device of claim 27, wherein said displaying means comprises a plurality of interferometric modulators.

30. In an array of electrical devices formed in rows and columns and coupled to a plurality of row electrodes and a plurality of column electrodes, a method of determining an electrical characteristic or operational state of a selected electrical device located in a selected row of the array, in a selected column of the array, the method comprising:

providing a predetermined first value of an electrical characteristic corresponding to a first value of the electrical characteristic between a selected row electrode and a selected column electrode, the plurality of column electrodes being driven to a common voltage and at least a portion of non-selected row electrodes floating, the selected electrical device being coupled to the selected row electrode and the selected column electrode;

providing a predetermined second value of an electrical characteristic corresponding to a second value of the electrical characteristic between the selected row electrode and the selected column electrode, the plurality of row electrodes being driven to a common voltage and at least a portion of non-selected column electrodes floating;

measuring a third value of an electrical characteristic between selected row electrode and the selected column electrode, the non-selected column electrodes and row electrodes floating; and

determining a resulting electrical characteristic or operational state of the selected electrical device based at least in part on the first, second, and third measured values of the electrical characteristic.

31. The method of claim 30, wherein the electrical characteristic is capacitance, and wherein determining capacitance (C_selected—

<sub>display—

device</sub>) of the selected electrical device comprises using the first value (C<sub>first—

value</sub>) the second value (C<sub>second—

value</sub>), and the third value (C<sub>third—

value</sub>) in substantially the following relationship;

$C_{\mathrm{selected}<br><br>\_<br><br>\mathrm{display}<br><br>\_<br><br>\mathrm{device}}=\frac{1}{2}<br><br>\left(C_{s<br><br>\mathrm{econd}<br><br>\_<br><br>\mathrm{value}}+C_{\mathrm{third}<br><br>\_<br><br>\mathrm{value}}-\frac{C_{s<br><br>\mathrm{econd}<br><br>\_<br><br>\mathrm{value}}<br><br>C_{\mathrm{third}<br><br>\_<br><br>\mathrm{value}}}{C_{\mathrm{first}<br><br>\_<br><br>\mathrm{value}}}\right)$