Method and apparatus of generating drive signal for light emitting element

Patent metadata

Field	Value
Publication number	US-12494151-B2
Application number	US-202218559247-A
Country	US
Kind code	B2
Filing date	May 24, 2022
Priority date	May 27, 2021
Publication date	Dec 9, 2025
Grant date	Dec 9, 2025

Abstract

A method for generating a drive signal for driving a light emitting element of a display. The method includes: dividing the M bits into M−N1+1 data ranges, each including N1 consecutive bits of the M bits; determining N2 bits for uniquely identifying the M−N1+1 data ranges; generating a coded signal of N1+N2 bits for representing the M bits of the input signal; based on the coded signal, generating the drive signal comprising a sequence of N1 bits, each bit of said sequence of N1 bits controlling a current through the light emitting element or a voltage across the light emitting element, during a time interval, one bit at a time.

First claim

The invention claimed is:

1 . A method for generating a drive signal for driving a light emitting element of a display, the method comprising:
receiving an input data comprising M bits, b 0 , b 1 , . . . , b M−1 , for driving the light emitting element, wherein each bit has a value of 0 or 1; grouping the M bits into M−N1+1 data ranges, each of the M−N1+1 data ranges comprising N1 consecutive bits of the M bits that are partially overlapping with N1 consecutive bits of another one of the M−N1+1 data ranges, wherein N1<M; determining a number of N2 bits for uniquely identifying the M−N1+1 data ranges; generating a coded signal for representing the M bits of the input signal, wherein the coded signal comprises N2+N1 bits,
a first part of the coded signal comprising N2 bits for identifying one of the M−N1+1 data ranges, wherein the N2 bits are a combination of 0 or 1 and each unique combination of N2 bits identifies one of the M−N1+1 data ranges, and
a second part of the coded signal comprising N1 bits being the N1 consecutive bits b i , . . . , b i+N1−1 , of the M bits corresponding to said identified one of the M−N1+1 data ranges, wherein N1+N2<M, i>=0, i+N1−1<=M−1;
based on the coded signal, generating the drive signal comprising a sequence of N1 bits, each bit of the sequence of N1 bits maintaining a respective bit position in the M bits, each bit of said sequence of N1 bits, having a corresponding value according to the bit position, controlling a current through the light emitting element or a voltage across the light emitting element, during a time interval, one bit at a time; wherein M, N1, N2 and i are natural numbers.

2 . The method of claim 1 , wherein the step of generating a coded signal comprises:
selecting N1 consecutive bits, b i , . . . , b i+N1−1 , of the M bits to be the second part of the coded signal, comprising: determining a most significant bit of the M bits having a value of 1, to be a most significant bit, b i+N−1 , of the selected N1 consecutive bits, such that the selected N1 consecutive bits are determined to be b i , . . . , b i+N1−1 ; if said most significant bit, b i+N1−1 , is less significant than b N1−1 , or if none of the M bits has a value of 1, the selected N1 consecutive bits are determined to be the least significant N1 bits, b 0 , . . . , b N1−1 , of the M bits.

3 . The method of claim 1 , wherein the step of determining N2 bits for uniquely identifying the M−N1+1 data ranges comprises:
calculating N2 by performing a ceiling function on log 2 (M−N1+1).

4 . The method of claim 1 , wherein the step of generating the drive signal comprises:
determining the time interval for each bit of said sequence of N1 bits.

5 . The method of claim 4 , wherein the step of determining the time interval, comprises:
selecting a pointer bit b x among the M bits, and determining its time interval T x to be T 0 ; for a more significant bit b x+j of the pointer bit b x , determining its time interval T x+j to be 2 j *T 0 ; and for a less significant bit b x−j of the pointer bit b x , determining its time interval T x−j to be 2 −j *T 0 ; wherein x and j are natural numbers, x+j<=M−1, and x−j>=0.

6 . The method of claim 1 , wherein said sequence of N1 bits controls the current through the light emitting element or the voltage across the light emitting element, for a fixed time period T.

7 . The method of claim 6 , wherein the fixed time period T is determined based on the time intervals of the most significant N1 consecutive bits, b M−N1 , . . . b M−1 , of the M bits;
wherein the fixed time period T is determined by summing the time intervals of the most significant N1 consecutive bits, b M−N1 , . . . , M−1, of the M bits, comprising: for each bit b x+j of the most significant N1 consecutive bits being more significant than the pointer bit b x , adding its timer interval T x+j , for the pointer bit b x , adding its timer interval T 0 , and for each bit b x−j of the most significant N1 consecutive bits being less significant than the pointer bit b x , adding one time interval T 0 .

8 . The method of claim 7 , wherein the fixed time period T is an integer multiple of T 0 , i.e. T=(2 M−x −1+x−M+N1)*T 0 ;
wherein a first 2 M−1−x of T 0 of the fixed time period T is reserved for the most significant bit, b M−1 , for controlling the current through the light emitting element or the voltage across the light emitting element;
a next 2 M−2−x of T 0 of the fixed time period T is reserved for the second most significant bit, b M−2 , for controlling the current through the light emitting element or the voltage across the light emitting element; and
a last T 0 is reserved for the least significant bit, b M−N1 , for controlling the current through the light emitting element or the voltage across the light emitting element.

9 . The method of claim 8 , wherein the step of generating the drive signal based on the coded signal comprises:
each bit of said N1 bits of the coded signal belonging to the most significant N1 consecutive bits, b M−N1 , . . . , b M−1 , controlling the current through the light emitting element or the voltage across the light emitting element for a period of a number of T 0 within the fixed timer period T reserved for this bit, and each bit of said N1 bits of the coded signal not belonging to the most significant N1 consecutive bits, b M−N1 , . . . , b M−1 , controlling the current through the light emitting element or the voltage across the light emitting element for a period of one T 0 within the fixed timer period T reserved for one of the most significant N1 consecutive bits which is not a part of said N1 bits.

10 . The method of claim 1 , comprising:
providing a reset signal to override the drive signal to force a bit of said sequence of the N1 bits to stop controlling the current or the voltage before an end of its time interval.

11 . The method of claim 10 , wherein the reset signal overrides a bit having a time interval shorter than T 0 and/or comprising providing a reset flag to enable or to disable the reset signal for each bit of said sequence of N1 bits.

12 . The method of claim 1 , wherein M is larger or equal to 16; and/or wherein N1 is equal to any of 8, 9, 10.

13 . The method of claim 1 , wherein the light emitting element is a pixel, or a sub-pixel.

14 . The method of claim 1 , wherein the drive signal is a Pulse-width Modulation, PWM, signal.

15 . The method of claim 14 , wherein a period of the PWM signal is the fixed time period T.

16 . An apparatus for generating a drive signal for driving a light emitting element of a display, the apparatus comprising:
a processing circuit configured to: group an input data comprising M bits, b 0 , b 1 , . . . , b M−1 , for driving the light emitting element into M−N1+1 data ranges, each of the M−N1+1 data ranges comprising N1 consecutive bits of the M bits that are partially overlapping with N1 consecutive bits of another one of the M−N1+1 data ranges, wherein N1<M, wherein each bit has a value of 0 or 1; determine a number of N2 bits for uniquely identifying the M−N1+1 data ranges; generate a coded signal for representing the M bits of the input signal, wherein the coded signal comprises N2+N1 bits,
a first part of the coded signal comprising N2 bits for identifying one of the M−N1+1 data ranges, wherein the N2 bits are a combination of 0 or 1 and each unique combination of N2 bits identifies one of the M−N1+1 data ranges, and
a second part of the coded signal comprising N1 bits being the N1 consecutive bits b i , . . . , b i+N1−1 ,

Assignees

• Barco Nv

Inventors

• Willem Patrick Albin
• Van Eessen Wim

Classifications

• G09G2300/0842

  forming a memory circuit, e.g. a dynamic memory with one capacitor · CPC title

• G09G3/3225

  using an active matrix · CPC title

• G09G3/2037

  with specific control of sub-frames corresponding to the least significant bits · CPC title

• G09G3/3216

  using a passive matrix · CPC title

• G09G2300/0876

  Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes · CPC title