# US 11,955,059 B2 · Apparatuses, systems, and methods for MicroLED (mLED) backplane architectures

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- Number: US 11,955,059 B2
- Document ID: US11955059B2
- Status: Granted
- Kind: B2
- Application number: 17/705,088
- Filed: 2022-03-25
- Published: 2022-10-13
- Granted: 2024-04-09
- Earliest claimed: 2021-03-26
- Assignees: Forth Dimension Display, Ltd
- Applicants: Forth Dimension Displays Ltd.
- Inventors: Christopher Robert Chalmers
- Web page: https://patentgrep.com/patent/US11955059B2

## CPC

- G09G 3/32: semiconductive, e.g. using light-emitting diodes [LED]
- G09G 3/2074: {using sub-pixels}
- G09G 3/2085: {Special arrangements for addressing the individual elements of the matrix, other than by driving respective rows and columns in combination}
- G09G 3/2018: {by time modulation using two or more time intervals}
- G09G 2300/0842: forming a memory circuit, e.g. a dynamic memory with one capacitor
- G09G 2300/0857: Static memory circuit, e.g. flip-flop
- G09G 2300/0861: with additional control of the display period without amending the charge stored in a pixel memory, e.g. by means of additional select electrodes
- G09G 2310/0251: Precharge or discharge of pixel before applying new pixel voltage
- G09G 2310/0259: with use of an analog or digital ramp generator in the column driver or in the pixel circuit
- G09G 2310/027: Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
- G09G 2310/0291: Details of output amplifiers or buffers arranged for use in a driving circuit
- G09G 2310/08: Details of timing specific for flat panels, other than clock recovery
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/0276: for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

Method, apparatuses, and systems are described to display image data to a sub-pixel within a micro-LED (mLED) display. A sub-pixel image data value is stored at the sub-pixel. The sub-pixel is turned to an ON state. A shared row counter value is provided to the sub-pixel. The shared row counter value and the sub-pixel image data value are compared at the sub-pixel. The sub-pixel is turned to an OFF state if the shared row counter value is equal to or greater than the sub-pixel image data value.

## Claims

### Claim 1

A method to drive a sub-pixel micro-light emitting diode (mLED) of a micro-LED (mLED) display, comprising:
driving a damp voltage onto an anode of the sub-pixel mLED only when the sub-pixel LED is in an OFF state; and
initiating an ON state for the sub-pixel mLED, the initiating further comprising:
applying a pre-charge voltage in a form of a pulse to the sub-pixel mLED for a first period of time only during the ON state, wherein the pre-charge voltage is greater than the clamp voltage; and
emitting light from the sub-pixel mLED during the ON state, the emitting continues for a second period of time, wherein the first period of time overlaps with the second period of time and the second period of time is greater than the first period of time.

### Claim 2 (depends on 1)

The method of claim 1, wherein the clamp voltage is derived from a first set of mLEDs, the first set of mLEDs are not in the mLED display.

### Claim 3 (depends on 2)

The method of claim 2, further comprising:
driving the first set of mLEDs with an adjustable current to ascertain a maximum leakage current that does not trigger emission of light from the first set of mLEDs;
storing a first voltage that corresponds to the maximum leakage current; and
using the first voltage to establish the clamp voltage.

### Claim 4 (depends on 1)

The method of claim 1, wherein the pre-charge voltage is derived from a second set of mLEDs, the second set of mLEDs are not in the mLED display.

### Claim 5 (depends on 4)

The method of claim 4, further comprising:
driving the second set of mLEDs with a current source to establish a drive current that triggers emission of light from the second set of mLEDs;
storing a second voltage that corresponds to the drive current; and
using the second voltage to establish the pre-charge voltage.

### Claim 6

A computer-readable storage medium storing program code for causing a data processing system to perform the steps comprising:
driving a clamp voltage onto an anode of a sub-pixel micro-light emitting diode (mLED) of a mLED display only when the sub-pixel mLED is in an OFF state; and
initiating an ON state for the sub-pixel mLED, the initiating further comprising:
applying a pre-charge voltage in a form of a pulse to the sub-pixel mLED for a first period of time only during the ON state, wherein the pre-charge voltage is greater than the clamp voltage; and
emitting light from the sub-pixel mLED during the ON state, the emitting continues for a second period of time, wherein the first period of time overlaps with the second period of time and the second period of time is greater than the first period of time.

### Claim 7 (depends on 6)

The computer-readable storage medium of claim 6, wherein the clamp voltage is derived from a first set of mLEDs, the first set of mLEDs are not in the mLED display.

### Claim 8 (depends on 7)

The computer-readable storage medium of claim 7, the steps further comprising:
driving the first set of mLEDs with an adjustable current to ascertain a maximum leakage current that does not trigger emission of light from the first set of mLEDs;
storing a first voltage that corresponds to the maximum leakage current; and
using the first voltage to establish the clamp voltage.

### Claim 9 (depends on 6)

The computer-readable storage medium of claim 6, wherein the pre-charge voltage is derived from a second set of mLEDs, the second set of mLEDs are not in the mLED display.

### Claim 10 (depends on 9)

The computer-readable storage medium of claim 9, the steps further comprising:
driving the second set of mLEDs with a current source to establish a drive current that triggers emission of light from the second set of mLEDs;
storing a second voltage that corresponds to the drive current; and
using the second voltage to establish the pre-charge voltage.

### Claim 11

A system to drive sub-pixel micro-light emitting diodes (mLEDs) of a micro-LED (mLED) display, comprising:
a sub-pixel mLED having an anode and a cathode;
a sub-pixel mLED current control transistor, configured to output a drive current;
a sub-pixel mLED enable transistor, an input of the sub-pixel mLED enable transistor coupled to an output of the sub-pixel mLED current control transistor and an output of the sub-pixel mLED enable transistor is coupled to the anode of the sub-pixel mLED;
a switchable pre-charge voltage, the switchable pre-charge voltage injectable between the sub-pixel mLED current control transistor and the sub-pixel mLED enable transistor;
a switchable clamp voltage, the switchable clamp voltage injectable between the sub-pixel mLED enable transistor and the anode of the sub-pixel mLED; and
a sub-pixel control module, the sub-pixel control module configured to drive the sub-pixel mLED as follows in order:
A. sub-pixel mLED OFF state, the switchable clamp voltage is switched ON;
B. sub-pixel mLED ON state, the pre-charge voltage is switched ON for a first period of time and the sub-pixel mLED enable transistor passes the drive current to the sub-pixel mLED for a second period of time, where the first period of time overlaps with the second period of time and the second period of time is longer than the first period of time.