# US 11,308,873 B2 · Redundancy assisted noise control for accumulated iterative compression error

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,308,873 B2
- Document ID: US11308873B2
- Status: Granted
- Kind: B2
- Application number: 16/542,233
- Filed: 2019-08-15
- Published: 2020-11-26
- Granted: 2022-04-19
- Earliest claimed: 2019-05-23
- Assignees: Samsung Display Co., Ltd.
- Applicants: Samsung Display Co., Ltd.
- Inventors: Amin Mobasher; Zehui Chen
- Web page: https://patentgrep.com/patent/US11308873B2

## CPC

- G09G 3/3208: organic, e.g. using organic light-emitting diodes [OLED]
- G09G 3/3225: using an active matrix
- G09G 3/20: for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix {no fixed position being assigned to or needed to be assigned to the individual characters or partial characters}
- G09G 2320/0233: Improving the luminance or brightness uniformity across the screen
- G09G 2320/0257: Reduction of after-image effects
- G09G 2320/0285: using tables for spatial correction of display data
- G09G 2320/029: by monitoring one or more pixels in the display panel, e.g. by monitoring a fixed reference pixel
- G09G 2320/0653: Controlling or limiting the speed of brightness adjustment of the illumination source
- G09G 2330/04: Display protection
- G09G 2330/06: Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
- G09G 2360/16: Calculation or use of calculated indices related to luminance levels in display data
- G09G 2370/04: Exchange of auxiliary data, i.e. other than image data, between monitor and graphics controller
- H03M 7/3059: {Digital compression and data reduction techniques where the original information is represented by a subset or similar information, e.g. lossy compression}
- H03M 7/6041: {Compression optimized for errors}
- H03M 13/1515: {Reed-Solomon codes}
- 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)
- H03M: CODING; DECODING; CODE CONVERSION IN GENERAL (using fluidic means F15C4/00; optical analogue/digital converters G02F7/00; coding, decoding or code conversion, specially adapted for particular applications, see the relevant subclasses, e.g. G01D, G01R, G06F, G06T, G09G, G10L, G11B, G11C, H04B, H04L, H04M, H04N; ciphering or deciphering for cryptography or other purposes involving the need for secrecy G09C)

## Abstract

A method of stress compensation in a display device includes accumulating a brightness value of images displayed by the display device, encoding the accumulated brightness value to preserve a protected portion of the accumulated brightness value, compressing the accumulated brightness value, storing the compressed accumulated brightness value in a memory, retrieving and decompressing the compressed accumulated brightness value to generate a decompressed value, and decoding the decompressed value based on the protected portion to generate a decoded value corresponding to the accumulated brightness value, the decoded value having lower compression noise than the decompressed value.

## Claims

### Claim 1

A method of stress compensation in a display device, the method comprising:
augmenting, by an adding circuit, a brightness value of an image displayed by the display device based on a previous decoded value to generate an accumulated brightness value;
encoding, by an encoder, the accumulated brightness value by selecting, for preservation in a memory, a protected portion of the accumulated brightness value, the protected portion comprising a plurality of bits from among bits of the accumulated brightness value;
compressing, by a compressor, the accumulated brightness value;
storing, by the compressor, the compressed accumulated brightness value in the memory;
retrieving and decompressing, by a decompressor, the compressed accumulated brightness value to generate a decompressed value;
decoding, by a decoder, the decompressed value based on the protected portion to generate a decoded value corresponding to the accumulated brightness value, the decoded value having lower compression noise than the decompressed value;
receiving, by the adding circuit, an output image to be displayed on the display device; and
adding, by the adding circuit, the decoded value to a brightness value of the output image to generate an updated accumulated brightness value.

### Claim 2 (depends on 1)

The method of claim 1, wherein the protected portion comprises k bits of the accumulated brightness value starting from a p-th bit of the accumulated brightness value (both p and k being integers greater than 1), and
wherein p+k−1 is less than a bit length of the accumulated brightness value.

### Claim 3 (depends on 2)

The method of claim 2, wherein the compression noise in the decompressed value is entirely contained within first (p+k−1)-th bits of the decompressed value.

### Claim 4 (depends on 1)

The method of claim 1, further comprising:
discarding, by a truncator, lesser significant bits of the decoded value preceding the protected portion.

### Claim 5 (depends on 1)

The method of claim 1, further comprising:
providing the decoded value to a compensator for compensating an input image for a stress of the display device.

### Claim 6 (depends on 1)

The method of claim 1, wherein the encoding the accumulated brightness value comprises:
identifying, by the encoder, the protected portion of the accumulated brightness value; and
storing, by the encoder, the protected portion in the memory.

### Claim 7 (depends on 6)

The method of claim 6, wherein the protected portion is stored in memory in an uncompressed state.

### Claim 8 (depends on 1)

The method of claim 1, wherein the decoding the decompressed value comprises:
identifying, by the decoder, a decompressed protected portion of the decompressed value;
calculating, by the decoder, a difference between the protected portion and the decompressed protected portion to generate an estimated compression noise; and
calculating, by the decoder, the decoded value based on the decompressed value and the estimated compression noise to mitigate compression noise in the decom pressed value.

### Claim 9 (depends on 8)

The method of claim 8, wherein the decompressed protected portion of the decompressed value corresponds in bit position to the protected portion of the accumulated brightness value.

### Claim 10 (depends on 8)

The method of claim 8, wherein the calculating the difference comprises:
calculating, by the decoder, a first error (E1) and a second error (E2) as:
E1=({tilde over (k)}k−xk)mod 2k, and
E2=(xk−{tilde over (x)}k)mod 2k
where Xk represents the protected portion of the accumulated brightness value, {tilde over (x)}k represents the decompressed protected portion, and mod represents a modulo operation.

### Claim 11 (depends on 10)

The method of claim 10, wherein calculating the decoded value comprises:
determining, by the decoder, that the first error is less than the second error; and
in response to the determination, calculating, by the decoder, the decoded value ({circumflex over (X)}) as
{circumflex over (X)}={tilde over (X)}−E1·2p−1
where {tilde over (X)} represents the decompressed value and p represents a first bit location of the protected portion in the accumulated brightness value.

### Claim 12 (depends on 10)

The method of claim 10, wherein calculating the decoded value comprises:
determining, by the decoder, that the first error is greater than the second error; and
in response to the determination, calculating, by the decoder, the decoded value ({circumflex over (X)}) as
{circumflex over (X)}={tilde over (X)}−E2·2p−1
where {tilde over (X)} represents the decompressed value and p represents a first bit location of the protected portion in the accumulated brightness value.

### Claim 13 (depends on 10)

The method of claim 10, wherein calculating the decoded value comprises:
determining, by the decoder, that the first error is equal to the second error; and
determining, by the decoder, the decoded value as the decompressed value.

### Claim 14 (depends on 1)

The method of claim 1, wherein the encoding the accumulated brightness value comprises:
replicating, by the encoder, the protected portion of a plurality of times to form a binary replica string, and
wherein the method further comprises:
compressing, by the compressor, the binary replica string;
storing, by the compressor, the compressed binary replica string in the memory; and
retrieving and decompressing, by the decompressor, the compressed binary replica string to generate a decompressed binary replica string.

### Claim 15 (depends on 14)

The method of claim 14, wherein the decoding the decompressed value comprises:
calculating, by the decoder, a decoded protected portion to estimate the protected portion by applying a maximum likelihood decoding (MLD) process to the decompressed binary replica string;
calculating, by the decoder, a difference between the decoded protected portion and a decompressed protected portion of the decompressed value to generate an estimated compression noise; and
calculating, by the decoder, the decoded value based on the decompressed value and the estimated compression noise to mitigate compression noise in the decompressed value.

### Claim 16 (depends on 1)

The method of claim 1, wherein the encoding the accumulated brightness value comprises:
coding, by the encoder, the protected portion to generate a plurality of parity bits,
wherein the compressing the accumulated brightness value comprises:
compressing, by the compressor, the parity bits along with the accumulated brightness value, and
wherein the decompressing the compressed accumulated brightness value comprises:
decompressing, by the decompressor, the compressed parity bits together with the compressed accumulated brightness value to generate a decompressed protected portion and decompressed parity bits.

### Claim 17 (depends on 16)

The method of claim 16, wherein the coding of the protected portion is according to a reed-solomon code applied across slices of the accumulated brightness value, and
wherein the parity bits are compressed via a different compression than the accumulated brightness value.

### Claim 18 (depends on 16)

The method of claim 16, wherein the decoding the decompressed value comprises:
calculating, by the decoder, a decoded protected portion to estimate the protected portion based on the decompressed protected portion and decompressed parity bits;
calculating, by the decoder, a difference between the decoded protected portion and the decompressed protected portion to generate an estimated compression noise; and
calculating, by the decoder, the decoded value based on the decompressed value and the estimated compression noise to mitigate compression noise in the decompressed value.

### Claim 19

A system for performing stress compensation in a display device, the system comprising:
a memory; and
a processing circuit comprising an adding circuit, the processing circuit being configured to perform:
augmenting, by an adding circuit, a brightness value of an image displayed by the display device based on a previous decoded value to generate an accumulated brightness value;
encoding the accumulated brightness value by selecting, for preservation in the memory, a protected portion of the accumulated brightness value, the protected portion comprising a plurality of bits from among bits of the accumulated brightness value;
compressing the accumulated brightness value;
storing the compressed accumulated brightness value in the memory;
retrieving and decompressing the compressed accumulated brightness value to generate a decompressed value;
decoding the decompressed value based on the protected portion to generate a decoded value corresponding to the accumulated brightness value, the decoded value having lower compression noise than the decompressed value;
receiving, by the adding circuit, an output image to be displayed on the display device; and
adding, by the adding circuit, the decoded value to a brightness value of the output image to generate an updated accumulated brightness value.