Circuits for controlling display apparatus

• US 9,400,382 B2
• Filed: 06/17/2015
• Issued: 07/26/2016
• Est. Priority Date: 01/05/2010
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Pixtronix, Incorporated (Qualcomm, Inc.)
• Inventors: Lewis, Stephen R., English, Stephen, McAllister, Abraham
• Primary Examiner(s): Patel, Kumar
• Assistant Examiner(s): Said, Mansour M
• Application Number:
  US14/741,874
• Publication Number:
  US 20150286047A1
• Time in Patent Office: 405 Days
• US Class Current: 1/1
• CPC Class Codes: G02B 26/04 by periodically varying the intensity of light, e.g. using choppers shutters, diaphragms for cameras G03B9/00; devices for eliminating or reducing the effect of flicker in projection systems G03B21/40
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means
• CPC Class Codes: G09G 2300/0456 with a reflective area and a transmissive area combined in one pixel, such as in transflectance pixels
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2300/0814 used for selection purposes, e.g. logical AND for partial update
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0857 Static memory circuit, e.g. flip-flop
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/0262 The addressing of the pixel, in a display other than an active matrix LCD, involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependent on signals of two data electrodes
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/2074 using sub-pixels
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: G09G 3/3433 using light modulating elements actuated by an electric field and being other than liquid crystal devices and electrochromic devices using liquid crystal devices G09G3/36; using electrochromic devices G09G3/38
• 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: H03K 3/037 Bistable circuits

Abstract

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.

Claims

1. A display apparatus comprising:

at least one actuation line interconnect;

at least one data line interconnect;

an array of pixels, each pixel in the array of pixels comprising;

a Microelectromechanical Systems (MEMS)-based light modulator a first actuator and a second actuator, the first and the second actuators capable of controlling an optical state of the MEMS-based light modulator; and

a dual inverter latch including;

a first inverter including;

a first input electrically coupled to receive a data voltage provided by the at least one data line interconnect, and

a first output electrically coupled with the first actuator, the first output being further coupled to receive an actuation voltage provided by the at least one actuation line interconnect, and

wherein the first inverter is configured to control a logical state on the first actuator based on the data voltage and the actuation voltage; and

a second inverter cross-coupled with the first inverter and including;

a second input electrically coupled with the first output, and

a second output electrically coupled with the second actuator, the second output being further coupled to the first input, and

wherein the second inverter is configured to maintain a logical state on the second actuator at a logical value opposite of a logical value of the logical state on the first actuator.

2. The display apparatus of claim 1, further including a transparent substrate, the array of pixels being on or over the transparent substrate.

3. The display apparatus of claim 1, wherein each pixel further includes a cascode circuit electrically coupled with at least one of the first inverter or the second inverter.

4. The display apparatus of claim 1, wherein each pixel further includes a data store coupled with the first input and capable of storing the data voltage.

5. The display apparatus of claim 4, wherein each pixel further includes an update switch capable of electrically coupling the data store to the first inverter to allow the data voltage to pass from the data store to the first input.

6. The display apparatus of claim 5, further including an update line interconnect capable of supplying a voltage to control the update switches in a plurality of the pixels associated with a plurality of rows and a plurality of columns in the array of pixels.

7. The display apparatus of claim 6, wherein the update switch is capable of electrically decoupling the data store from the first inverter responsive to a voltage supplied by the update line interconnect to prevent current from flowing between the data store and the dual inverter latch.

8. The display apparatus of claim 6, wherein the actuation line interconnect is further capable of providing an intermediate voltage to the first and the second inverters to latch the logical states on the first and the second actuators based on the data voltage.

9. The display apparatus of claim 6, further including

a row line interconnect capable of supplying an enable voltage;

and

a data loading switch capable of passing the data voltage to the data store based on the enable voltage.

10. The display apparatus of claim 9, wherein the data store comprises a capacitor, a first input of the capacitor being electrically coupled to the data loading switch and to the update switch, a second input of the capacitor being electrically coupled to a common line interconnect associated with a plurality of rows of pixels in the array of pixels.

11. The display apparatus of claim 10, wherein to update the logical states of the first and the second actuators of the pixel, the controller is capable of:

causing the common line interconnect to supply a common voltage;

causing the actuation line interconnect to supply a voltage approximately equal to the common voltage supplied by the common line interconnect;

causing the update line interconnect to supply the update voltage while the actuation line interconnect supplies the voltage approximately equal to the common voltage;

causing the actuation line interconnect to supply an intermediate voltage while the update line interconnect supplies the update voltage and

causing the update line interconnect to stop supplying the update voltage after causing the actuation line interconnect to supply the intermediate voltage.

12. The display apparatus of claim 11, wherein the update voltage supplied to the update switch causes the update switch to enable the data voltage to pass

from the data store to the dual inverter latch.

13. The display apparatus of claim 11, wherein to actuate the first or the second actuator, the controller is capable of causing the actuate line interconnect to supply the actuation voltage after causing the update line interconnect to stop supplying the update voltage.

14. The display apparatus of claim 9, further including a controller capable of:

controlling the data voltage supplied by the data line interconnect;

controlling the voltage supplied by the row line interconnect;

controlling the voltage supplied by the update line interconnect; and

controlling the voltage supplied by the actuation line interconnect.

15. The display apparatus of claim 14, wherein the controller is capable of loading data into the data store of a pixel in a particular row and a particular column of the array of pixels by:

causing the row line interconnect associated with the particular row to supply the enable voltage to the data loading switch in the pixel;

determining a next optical state of the MEMS-based light modulator in the pixel; and

causing the data line interconnect associated with the particular column to supply the data voltage corresponding to the next optical state to the data loading switch.

16. The display apparatus of claim 15, the controller further capable of:

updating the logical states of the first and the second actuators of the pixel based at least in part on the loaded data such that a full actuation voltage is applied to only one of the first and the second actuators.

17. The display apparatus of claim 9, wherein the data store comprises a capacitor, a first input of the capacitor being electrically coupled to the data loading switch and to the update switch, a second input of the capacitor being electrically coupled to a row line interconnect associated with a next row in the array of pixels next to the particular row.

18. The display apparatus of claim 9, wherein the data store comprises a capacitor, a first input of the capacitor being electrically coupled to the data loading switch and to the update switch, a second input of the capacitor being electrically coupled to a shutter line interconnect associated with the MEMS-based light modulator.

19. The display apparatus of claim 1, wherein each MEMS-based light modulator includes a movable element capable of movement responsive to actuation of at least one of the first or the second actuators between a first optical state enabling light to pass through the light modulator and a second optical state disabling light from passing through the light modulator.

20. The display apparatus of claim 19, wherein:

the first actuator is capable of moving the movable element to the first optical state when the logical state on the first actuator is a first logical state; and

the second actuator is capable of moving the movable element to the second optical state when the logical state on the second actuator is the first logical state.

21. The display apparatus of claim 20, further including a substrate including an array of apertures, wherein the movable element includes a shutter over at least one aperture in the array of apertures, the shutter capable of transverse movement responsive to the first and the second actuators along a plane parallel to the substrate between the first optical state and the second optical state.