System and method of sensing actuation and release voltages of an interferometric modulator
View Patent ↗A method for sensing the actuation and/or release voltages of a electromechanical system or a microelectromechanical device include applying a varying voltage to the device and sensing its state and different voltage levels. In one embodiment, the device is part of a system comprising an array of interferometric modulators suitable for a display. The method can be used to compensate for temperature dependent changes in display pixel characteristics.
1. A mirror system comprising:
an interferometric modulator array of mirrors;
a timing control circuit for activating each of the mirrors;
a drive circuit configured to apply one or more test voltages or currents; and
a sensing circuit configured to sense a state of at least one of the mirrors and determine one or both of an actuation voltage and a release voltage based at least in part on the sensed state of the mirrors, wherein the sensing circuit comprises test circuitry configured to compare a sensed voltage of said at least one of the mirrors to a threshold voltage.
2. The mirror system of claim 1 , wherein the sensing circuit include resistive and capacitive elements in parallel.
3. The mirror system of claim 1 , wherein the sensing circuit comprises an integrator with one or more passive feedback components.
4. The mirror system of claim 1 , wherein the timing control circuit and the sensing circuit are embodied in an integrated circuit.
5. The mirror system of claim 1 , wherein the mirror system comprises an electromechanical system (EMS) or a microelectromechanical system (MEMS).
6. The mirror system of claim 1 , wherein the mirrors comprise any reflective surface.
7. The mirror system of claim 1 , wherein the mirrors can be positioned in a reflective position and a non-reflective position.
8. The mirror system of claim 1 , wherein the timing control circuit controls an activation of the mirror.
9. The mirror system of claim 1 , wherein the mirrors are movable.
10. A method of pixel state sensing for modifying a drive voltage of an array of mirrors and a timing control circuit for controlling each of the mirrors, the method comprising:
applying a first test voltage or current to charge a mirror for a predetermined amount of time;
sensing a first state of the mirror to determine a first actuation or release voltage;
applying a second test voltage or current to charge the mirror for the predetermined amount of time;
sensing a second state of the mirror to determine a second actuation or release voltage; and
modifying the drive voltage based on the determined first and second actuation or release voltages to control a voltage at which the mirror is actuated or released.
11. A system for calibrating a drive voltage for an array of mirrors and a timing control circuit for controlling each of the mirrors, the system comprising:
means for applying a first test voltage or current to charge a mirror for a predetermined amount of time;
means for sensing a first state of the mirror to determine a first actuation or release voltage;
means for applying a second test voltage or current to charge the mirror for the predetermined amount of time;
means for sensing a second state of the mirror to determine a second actuation or release voltage; and
means for modifying the drive voltage based on the determined first and second actuation or release voltages to control a voltage at which the mirror is actuated or released.