# US 12,518,677 B1 · Apparatuses, systems, and methods for MicroLED (mLED) backplane architectures

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- Number: US 12,518,677 B1
- Document ID: US12518677B1
- Status: Granted
- Kind: B1
- Application number: 18/628,546
- Filed: 2024-04-05
- Granted: 2026-01-06
- Earliest claimed: 2021-03-26
- Assignees: Forth Dimension Display, Ltd
- Applicants: Forth Dimension Displays Ltd.
- Inventors: Christopher Robert Chalmers; Mladen Panovic; Debra Jane Lefley; Jason Darren Drew; Jedrzej Nowakowski; Mark Newsam; Neil Mallory; Robert Charles Beat; Ruiyan Zhao
- Web page: https://patentgrep.com/patent/US12518677B1

## 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 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 enable transistor is coupled to the anode of the sub-pixel mLED, wherein a switchable pre-charge voltage is injectable between the sub-pixel mLED current control transistor and the sub-pixel mLED enable transistor and a switchable clamp voltage is 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, the sub-pixel control module comprising:
placing the sub-pixel mLED in an OFF state when the switchable clamp voltage is switched ON; and
placing the sub-pixel mLED in an ON state when the pre-charge voltage is switched ON for a first period of time, the sub-pixel mLED enable transistor to pass 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, wherein the clamp voltage is derived from a first set of mLEDs, the first set of mLEDs are not in the mLED display.

### Claim 2 (depends on 1)

The system of claim 1, 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 value, the first value is representative of a first voltage that corresponds to the maximum leakage current; and
using the first value to establish the clamp voltage.

### Claim 3 (depends on 2)

The system of claim 2, wherein the first value is the first voltage.

### Claim 4

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 enable transistor is coupled to the anode of the sub-pixel mLED, wherein a switchable pre-charge voltage is injectable between the sub-pixel mLED current control transistor and the sub-pixel mLED enable transistor and a switchable clamp voltage is 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, the sub-pixel control module comprising:
placing the sub-pixel mLED in an OFF state when the switchable clamp voltage is switched ON; and
placing the sub-pixel mLED in an ON state when the pre-charge voltage is switched ON for a first period of time, the sub-pixel mLED enable transistor to pass 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, 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 system 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 value, the second value is representative of a second voltage that corresponds to the drive current; and
using the second value to establish the pre-charge voltage.

### Claim 6 (depends on 5)

The system of claim 5, wherein the second value is the second voltage.

### Claim 7

A method to drive a sub-pixel micro-light emitting diode (mLED) of a micro-LED (mLED) display, comprising:
placing the sub-pixel mLED in an OFF state when a switchable clamp voltage is switched ON; and
placing the sub-pixel mLED in an ON state, wherein a pre-charge voltage is switched ON for a first period of time and a sub-pixel mLED enable transistor passes a 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, 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 method of claim 7, 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 value, the first value is representative of a first voltage that corresponds to the maximum leakage current; and
using the first value to establish the clamp voltage.

### Claim 9 (depends on 8)

The method of claim 8, wherein the second value is the second voltage.

### Claim 10

A method to drive a sub-pixel micro-light emitting diode (mLED) of a micro-LED (mLED) display, comprising:
placing the sub-pixel mLED in an OFF state when a switchable clamp voltage is switched ON; and
placing the sub-pixel mLED in an ON state, wherein a pre-charge voltage is switched ON for a first period of time and a sub-pixel mLED enable transistor passes a 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, 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 11 (depends on 10)

The method of claim 10, 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 value, the second value is representative of a second voltage that corresponds to the drive current; and
using the second value to establish the pre-charge voltage.

### Claim 12 (depends on 11)

The method of claim 11, wherein the second value is the second voltage.

### Claim 13

A method to drive a sub-pixel micro-light emitting diode (mLED) of a micro-LED (mLED) display, comprising:
driving a clamp voltage onto an anode of the sub-pixel mLED; and
initiating an ON state for the sub-pixel mLED, the initiating further comprising:
applying a pre-charge voltage to the sub-pixel mLED for a first period of time, wherein the pre-charge voltage is greater than the clamp voltage; and
emitting light from the sub-pixel mLED during the ON state, wherein the clamp voltage is derived from a first set of mLEDs, the first set of mLEDs are not in the mLED display, 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 value, the first value is representative of a first voltage that corresponds to the maximum leakage current; and
using the first value to establish the clamp voltage, wherein the first value is the first voltage.

### Claim 14

A method to drive a sub-pixel micro-light emitting diode (mLED) of a micro-LED (mLED) display, comprising:
driving a clamp voltage onto an anode of the sub-pixel mLED; and
initiating an ON state for the sub-pixel mLED, the initiating further comprising:
applying a pre-charge voltage to the sub-pixel mLED for a first period of time, wherein the pre-charge voltage is greater than the clamp voltage; and
emitting light from the sub-pixel mLED during the ON state, wherein the pre-charge voltage is derived from a second set of mLEDs, the second set of mLEDs are not in the mLED display, 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 value, the second value is representative of a second voltage that corresponds to the drive current; and
using the second value to establish the pre-charge voltage, wherein the second value is the second voltage.

### Claim 15

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 mLED of a micro-LED (mLED) display; and
initiating an ON state for the sub-pixel mLED, the initiating further comprising:
applying a pre-charge voltage to the sub-pixel mLED for a first period of time, wherein the pre-charge voltage is greater than the clamp voltage; and
emitting light from the sub-pixel mLED during the ON state, wherein the clamp voltage is derived from a first set of mLEDs, the first set of mLEDs are not in the mLED display, 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 value, the first value is representative of a first voltage that corresponds to the maximum leakage current; and
using the first value to establish the clamp voltage, wherein the first value is the first voltage.

### Claim 16

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 mLED of a micro-LED (mLED) display; and
initiating an ON state for the sub-pixel mLED, the initiating further comprising:
applying a pre-charge voltage to the sub-pixel mLED for a first period of time, wherein the pre-charge voltage is greater than the clamp voltage; and
emitting light from the sub-pixel mLED during the ON state, wherein the pre-charge voltage is derived from a second set of mLEDs, the second set of mLEDs are not in the mLED display, 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 value, the second value is representative of a second voltage that corresponds to the drive current; and
using the second value to establish the pre-charge voltage, wherein the second value is the second voltage.