Capacitance gap calibration

• US 7,242,482 B2
• Filed: 08/30/2005
• Issued: 07/10/2007
• Est. Priority Date: 08/30/2005
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Brown, Matthew, Martin, Eric
• Primary Examiner(s): Toatley, Jr.; Gregory J.
• Assistant Examiner(s): Lyons; Michael A
• Application Number:
  US11/214,698
• Publication Number:
  US 20070046950A1
• Time in Patent Office: 679 Days
• Field of Search: 356/454, 356/505, 356/506, 356/519
• US Class Current: 356/506
• 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 2320/029 by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
• CPC Class Codes: G09G 3/3466 based on interferometric effect

Abstract

A method for calibrating a display device comprises controlling an applied voltage to at least one fabry-perot interferometer pixel through a plurality of switches. The at least one fabry-perot interferometer pixel has a top and a bottom plate defining a gap therebetween wherein the at least one fabry-perot interferometer pixel produces a selected output color in response to the applied voltage. The method further includes controlling a test voltage to the at least one fabry-perot interferometer pixel through the plurality of switches during a calibration sequence to determine a gap capacitance in the at least one fabry-perot interferometer. The gap capacitance represents the relative position of the top plate with respect to the bottom plate.

Claims

1. A method for calibrating a display device, comprising:

controlling an applied voltage to at least one fabry-perot interferometer pixel through a plurality of switches, said at least one fabry-perot interferometer pixel having a top and a bottom plate defining a gap therebetween;

wherein said at least one fabry-perot interferometer pixel produces a selected output color in response to said applied voltage; and

controlling a test voltage to said at least one fabry-perot interferometer pixel through said plurality of switches during a calibration sequence to determine a gap capacitance in said at least one fabry-perot interferometer;

wherein said gap capacitance represents a relative position of said top plate with respect to said bottom plate.

2. The method according to claim 1, further including:

configuring said plurality of switches to cycle on and off according to a predetermined frequency; and

measuring a current in said at least one fabry-perot interferometer pixel through said plurality of switches.

3. The method according to claim 1, further comprising:

applying a DC bias voltage to said at least one fabry-perot interferometer pixel to maintain a predetermined relative position between said top and said bottom plates.

4. The method according to claim 1, further comprising:

comparing said test voltage and said gap capacitance to a previous gap capacitance to determine a change in a relationship between said test voltage and said gap capacitance.

5. The method according to claim 4, further comprising:

adjusting said applied voltage to said at least one fabry-perot interferometer pixel through a plurality of switches based on a change in said relationship between said test voltage and gap capacitance.

6. The method according to claim 1, further comprising:

generating a database containing information relating to a relationship between said test voltage and said gap capacitance.

7. A method for calibrating a display device using a switched capacitor technique, comprising:

controlling an applied voltage to at least one fabry-perot interferometer pixel through a plurality of switches, said at least one fabry-perot interferometer pixel having a top and a bottom plate defining a gap therebetween;

wherein said at least one fabry-perot interferometer pixel produces a selected output color in response to said applied voltage;

controlling a test voltage to said at least one fabry-perot interferometer pixel through said plurality of switches during a calibration sequence by cycling said switches on and off at a predetermined frequency;

measuring a current in said at least one fabry-perot interferometer pixel through said plurality of switches; and

determining a gap capacitance in said at least one fabry-perot interferometer using said test voltage, said predetermined frequency, and said current.

8. The method according to claim 7, wherein said plurality of switches includes at least one pull-up and at least one pull-down switch.

9. The method according to claim 7, further comprising:

applying a DC bias voltage to said at least one fabry-perot interferometer pixel to maintain a predetermined relative position between said top and said bottom plates.

10. The method according to claim 7, wherein said at least one fabry-perot interferometer pixel is an array of fabry-perot interferometer pixels.

11. The method according to claim 10, wherein the step of measuring the current further includes measuring the current in said array of fabry-perot interferometer pixels simultaneously.

12. The method according to claim 7, further comprising:

comparing said test voltage and said gap capacitance to a previous gap capacitance to determine a change in a relationship between said test voltage and said gap capacitance.

13. A display device, comprising:

a means for controlling an applied voltage to at least one fabry-perot interferometer pixel through a plurality of switches, said at least one fabry-perot interferometer pixel having a top and a bottom plate defining a gap therebetween;

wherein said at least one fabry-perot interferometer pixel produces a selected output color in response to said applied voltage;

a means for controlling a test voltage to said at least one fabry-perot interferometer pixel through said plurality of switches during a calibration sequence by cycling said switches on and off at a predetermined frequency;

a means for measuring the current in said at least one fabry-perot interferometer pixel through said plurality of switches; and

a means for determining a gap capacitance in said at least one fabry-perot interferometer using said test voltage, said predetermined frequency, and said current.

14. The display device according to claim 13, further comprising:

a means for applying a DC bias voltage to said at least one fabry-perot interferometer pixel to maintain a predetermined relative position between said top and said bottom plates.

15. A display device, comprising:

at least one fabry-perot interferometer pixel having a top and a bottom plate defining a gap therebetween;

a plurality of switches configured to control a predetermined applied voltage to said at least one fabry-perot interferometer pixel;

wherein said at least one fabry-perot interferometer pixel is configured to produce a selected output color in response to said predetermined applied voltage; and

a test voltage applied through said plurality of switches to said at least one fabry-perot interferometer pixel during a calibration sequence to determine a capacitance in said gap of said at least one fabry-perot interferometer pixel.

16. A display device according to claim 15, wherein said plurality of switches includes at least one pull-up and at least one pull-down switch.

17. A display device according to claim 15, further including a DC bias voltage applied to said at least one fabry-perot interferometer pixel to maintain a predetermined relative position between said top and said bottom plates.

18. A display device according to claim 15, further including:

a closed loop feed back system configured to calibrate said display device by comparing said test voltage and said gap capacitance to a previously determined gap capacitance to detect a change in a relationship between said test voltage and said gap capacitance.

19. An image processing unit having instructions thereon for calibrating a display device, said instructions being configured to instruct said processing unit to perform the steps of:

controlling an applied voltage to at least one fabry-perot interferometer pixel through a plurality of switches, said at least one fabry-perot interferometer pixel having a top and a bottom plate defining a gap therebetween;

wherein said at least one fabry-perot interferometer pixel produces a selected output color in response to said applied voltage;

controlling a test voltage to said at least one fabry-perot interferometer pixel through said plurality of switches during a calibration sequence to determine a gap capacitance in said at least one fabry-perot interferometer;

wherein said gap capacitance represents a relative position of said top plate with respect to said bottom plate.

20. The image processing unit of claim 19, further having instructions thereon for performing the step of:

configuring said plurality of switches to cycle on and off according to a predetermined frequency; and

measuring a current in said at least one fabry-perot interferometer pixel through said plurality of switches.

21. The image processing unit of claim 19, further having instructions thereon for performing the step of:

applying a DC bias voltage to said at least one fabry-perot interferometer pixel to maintain a predetermined relative position between said top and said bottom plates.

22. The image processing unit of claim 19, further having instructions thereon for performing the step of:

comparing said test voltage and said gap capacitance to a previous gap capacitance to determine a change in a relationship between said test voltage and said gap capacitance.

23. The image processing unit of claim 19, further having instructions thereon for performing the step of:

adjusting said applied voltage to said at least one fabry-perot interferometer pixel through a plurality of switches based on a change in said relationship between said test voltage and gap capacitance.

24. The image processing unit of claim 19, further having instructions thereon for performing the step of:

generating a database containing information relating to a relationship between said test voltage and said gap capacitance.

25. A method for calibrating a display device, comprising:

controlling an applied voltage to at least one fabry-perot interferometer pixel through a plurality of switches, said at least one fabry-perot interferometer pixel having a top and a bottom plate defining a gap therebetween;

wherein said at least one fabry-perot interferometer pixel produces a selected output color in response to said applied voltage;

applying a DC bias voltage to said at least one fabry-perot interferometer pixel to maintain a predetermined relative position between said top and said bottom plates;

controlling a test voltage to said at least one fabry-perot interferometer pixel through said plurality of switches during a calibration sequence by cycling said switches on and off at a predetermined frequency;

measuring a current in said at least one fabry-perot interferometer pixel through said plurality of switches;

determining a gap capacitance in said at least one fabry-perot interferometer using said test voltage, said predetermined frequency, and said current;

comparing said test voltage and said gap capacitance to a previous gap capacitance to determine a change in a relationship between said test voltage and said gap capacitance; and

adjusting said applied voltage to said at least one fabry-perot interferometer pixel through a plurality of switches based on a change in said relationship between said test voltage and gap capacitance.