CIRCUITS FOR CONTROLLING DISPLAY APPARATUS
The invention relates to methods and apparatus for forming images on a display utilizing a control matrix to control the movement of MEMs-based light modulators.
1 . A display apparatus comprising:
a substrate;
an array of pixels, wherein each pixel includes:
at least one actuator; and
at least one MEMS device capable of modulating light, wherein each of the MEMS devices can be driven to at least three states, including: a substantially open state, a substantially closed state, and a partially open state; and
a control matrix for driving each of the MEMS devices in the array of pixels into one of the at least three states.
2 . The display apparatus of claim 1 , wherein the control matrix drives a MEMS device into the substantially open state by applying an actuation voltage across the at least one actuator.
3 . The display apparatus of claim 2 , wherein the control matrix drives a MEMS device into the substantially closed state by applying an actuation voltage across the at least one actuator.
4 . The display apparatus of claim 3 , wherein the control matrix drives a MEMS device into the partially open state by applying an intermediate voltage across the at least one actuator.
5 . The display apparatus of claim 4 , wherein the intermediate voltage is between a ground voltage and the actuation voltage.
6 . The display apparatus of claim 3 , wherein the at least one actuator comprises opposing first and second actuators.
7 . The display apparatus of claim 6 , wherein the control matrix drives a MEMS device into the partially open state by applying a pair of complementary voltages that, when applied simultaneously across the opposing first and second actuators, results in controlled states of partial opening.
8 . The display apparatus of claim 1 , wherein the control matrix includes:
a plurality of scan-line interconnects running in a first direction, each enabling a plurality of pixels along the first direction to respond to data voltages; and
a plurality of data interconnects running in a second direction perpendicular to the first direction, each providing data voltages to a plurality of pixels along the second direction.
9 . The display apparatus of claim 1 , wherein the substrate is transparent.
10 . The display apparatus of claim 1 , wherein the MEMS device modulates light by moving transversely through a path of a propagating ray of light.
11 . The display apparatus of claim 1 , further comprising a restoring spring opposing the at least one actuator.
12 . The display apparatus of claim 1 , wherein the control matrix includes:
an actuation voltage interconnect for applying an actuation voltage to the at least one actuator;
a grayscale switch electrically connected between the actuation voltage interconnect and the at least one actuator; and
a data voltage interconnect coupled to the grayscale switch, wherein a data voltage on the data voltage interconnect controls the grayscale switch.
13 . The display apparatus of claim 12 , wherein the actuation voltage applied to the at least one actuator varies in proportion to the data voltage resulting in an incremental displacement of the MEMS device.
14 . The display apparatus of claim 13 , wherein the controller drives a MEMS device into one of the at least three states based at least in part on the magnitude of the data voltage applied to the data voltage interconnect.
15 . The display apparatus of claim 14 , wherein the controller drives a MEMS device into one of the at least three states based at least in part on the duration of the data voltage applied to the data voltage interconnect.
16 . The display apparatus of claim 12 , further comprising a data store capacitor electrically coupled to the data voltage interconnect for storing the data voltage corresponding to the one of at least three states of the MEMS device.
17 . A method for displaying an image frame, comprising:
applying a write-enabling voltage to a scan-line interconnect in a first row of an array of MEMS devices;
applying a data voltage to at least one data-interconnect for a first MEMS device in the first row of the array; and
actuating the first MEMS device to drive the first MEMS device into the one of at least three states: a substantially open state, a substantially closed state, and a partially open state.
18 . The method of claim 17 , wherein the partially open state includes a range of partially open states between the substantially open state and the substantially closed state.
19 . The method of claim 18 , wherein the range of partially open states includes discrete ranges of partial MEMS device opening.
20 . The method of claim 17 , wherein displacement of the MEMS device is proportional to the data voltage.
21 . The method of claim 17 , wherein the data voltage comprises an analog data voltage.