# US 2019/0244556 A1 · Display device performing clock modulation and method of operating the display device

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- Number: US 2019/0244556 A1
- Document ID: US20190244556A1
- Status: Published application
- Kind: A1
- Application number: 16/268,066
- Filed: 2019-02-05
- Published: 2019-08-08
- Earliest claimed: 2018-02-06
- Assignees: Samsung Display Co., Ltd.
- Applicants: Samsung Display Co., Ltd.
- Inventors: Hyun-Sik YOON; Daeho HWANG; Jeong-Hyun KIM; Junpyo LEE; Sungsoo CHOI
- Web page: https://patentgrep.com/patent/US20190244556A1

## CPC

- 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 3/2096: {Details of the interface to the display terminal specific for a flat panel (suitable for both CRT and flat panel G09G5/006; specific for a CRT G09G1/167)}
- G09G 3/3225: using an active matrix
- G09G 3/3648: {using an active matrix (G09G3/367 - G09G3/3696 take precedence)}
- G09G 2310/0213: controlling the sequence of the scanning lines with respect to the patterns to be displayed, e.g. to save power
- G09G 2310/06: Details of flat display driving waveforms
- G09G 2310/067: Special waveforms for scanning, where no circuit details of the gate driver are given
- G09G 2310/08: Details of timing specific for flat panels, other than clock recovery
- G09G 2330/06: Handling electromagnetic interferences [EMI], covering emitted as well as received electromagnetic radiation
- G09G 2340/0435: Change or adaptation of the frame rate of the video stream
- 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

A method of operating a display device includes: receiving image data at an input frame frequency; generating a modulated clock signal by modulating an input clock signal according to a modulation frequency; randomly selecting an output frame frequency within a data frequency selection range, the input frame frequency being within the data frequency selection range; determining an output start timing of the image data based on the output frame frequency; initiating, at the output start timing, output of the image data in synchronization with the modulated clock signal; and displaying an image based on the outputted image data.

## Claims

### Claim 1

A method of operating a display device, the method comprising:
receiving image data at an input frame frequency;
generating a modulated clock signal by modulating an input clock signal according to a modulation frequency;
randomly selecting an output frame frequency within a data frequency selection range, the input frame frequency being within the data frequency selection range;
determining an output start timing of the image data based on the output frame frequency;
initiating, at the output start timing, output of the image data in synchronization with the modulated clock signal; and
displaying an image based on the outputted image data.

### Claim 2 (depends on 1)

The method of claim 1, wherein the randomly selecting the output frame frequency comprises randomly selecting a number of total vertical lines of frame data.

### Claim 3 (depends on 2)

The method of claim 2, wherein the randomly selecting the number of the total vertical lines of the frame data comprises:
randomly selecting a number of vertical lines to be added to or subtracted from a reference total vertical line number corresponding to the input frame frequency within a vertical line change range; and
determining the number of the total vertical lines by adding or subtracting the randomly selected number of the vertical lines to or from the reference total vertical line number.

### Claim 4 (depends on 2)

The method of claim 2, wherein the determining the output start timing of the image data comprises:
adjusting a vertical synchronization signal based on the randomly selected number of the total vertical lines; and
determining the output start timing of the image data based on the adjusted vertical synchronization signal.

### Claim 5 (depends on 1)

The method of claim 1, wherein the randomly selecting the output frame frequency comprises randomly selecting a number of total horizontal lines of frame data.

### Claim 6 (depends on 5)

The method of claim 5, wherein the randomly selecting the number of the total horizontal lines of the frame data comprises:
randomly selecting a number of horizontal lines to be added to or subtracted from a reference total horizontal line number corresponding to the input frame frequency within a horizontal line change range; and
determining the number of the total horizontal lines by adding or subtracting the randomly selected number of the horizontal lines to or from the reference total horizontal line number.

### Claim 7 (depends on 5)

The method of claim 5, wherein the determining the output start timing of the image data comprises:
adjusting a horizontal synchronization signal based on the randomly selected number of the total horizontal lines; and
determining the output start timing of the image data based on the adjusted horizontal synchronization signal.

### Claim 8

A method of operating a display device, the method comprising:
receiving image data at an input frame frequency;
randomly selecting a modulation frequency within a modulation frequency selection range, a reference modulation frequency being within the modulation frequency selection range;
generating a modulated clock signal by modulating an input clock signal with the randomly selected modulation frequency;
determining an output start timing of the image data based on the input frame frequency;
initiating, at the output start timing, output of the image data in synchronization with the modulated clock signal; and
displaying an image based on the outputted image data.

### Claim 9 (depends on 8)

The method of claim 8, wherein the randomly selecting the modulation frequency comprises:
randomly selecting a frequency to be added to or subtracted from the reference modulation frequency within a modulation frequency change range; and
determining the modulation frequency by adding or subtracting the randomly selected frequency to or from the reference modulation frequency.

### Claim 10

A display device comprising:
a display panel comprising a plurality of pixels;
a gate driver configured to provide gate signals to the plurality of pixels;
a data driver configured to provide data signals to the plurality of pixels; and
a timing controller configured to receive image data at an input frame frequency and to control the gate driver and the data driver, the timing controller comprising:
a clock modulation block configured to generate a modulated clock signal by modulating an input clock signal according to a modulation frequency; and
a frequency randomizer configured to randomly select an output frame frequency or the modulation frequency and to adjust an output timing of the image data based on the randomly selected output frame frequency or the modulated clock signal modulated according to the randomly selected modulation frequency.

### Claim 11 (depends on 10)

The display device of claim 10, wherein the frequency randomizer is configured to randomly select the output frame frequency within a data frequency selection range, the input frame frequency being within the data frequency selection range, and to determine an output start timing of the image data based on the randomly selected output frame frequency.

### Claim 12 (depends on 11)

The display device of claim 11, wherein the frequency randomizer comprises a total vertical line randomizer configured to randomly select a number of total vertical lines of frame data to randomly select the output frame frequency.

### Claim 13 (depends on 12)

The display device of claim 12, wherein the total vertical line randomizer is configured to receive a signal representing a vertical line change range, to randomly select a number of vertical lines to be added to or subtracted from a reference total vertical line number corresponding to the input frame frequency within the vertical line change range, to determine the number of the total vertical lines by adding or subtracting the randomly selected number of the vertical lines to or from the reference total vertical line number, and to adjust a vertical synchronization signal based on the randomly selected number of the total vertical lines.

### Claim 14 (depends on 13)

The display device of claim 13, wherein the frequency randomizer further comprises a synchronization circuit configured to determine the output start timing of the image data based on the adjusted vertical synchronization signal.

### Claim 15 (depends on 12)

The display device of claim 12, wherein the frequency randomizer further comprises a line buffer configured to temporarily store the image data in a unit of an active horizontal line.

### Claim 16 (depends on 11)

The display device of claim 11, wherein the frequency randomizer comprises a total horizontal line randomizer configured to randomly select a number of total horizontal lines of frame data to randomly select the output frame frequency.

### Claim 17 (depends on 16)

The display device of claim 16, wherein the total horizontal line randomizer is configured to receive a signal representing a horizontal line change range, to randomly select a number of horizontal lines to be added to or subtracted from a reference total horizontal line number corresponding to the input frame frequency within the horizontal line change range, to determine the number of the total horizontal lines by adding or subtracting the randomly selected number of the horizontal lines to or from the reference total horizontal line number, and to adjust a horizontal synchronization signal based on the randomly selected number of the total horizontal lines.

### Claim 18 (depends on 17)

The display device of claim 17, wherein the frequency randomizer further comprises a synchronization circuit configured to determine the output start timing of the image data based on the adjusted horizontal synchronization signal.

### Claim 19 (depends on 10)

The display device of claim 10, wherein the frequency randomizer comprises a modulation frequency randomizer configured to randomly select the modulation frequency within a modulation frequency selection range, a reference modulation frequency being within the modulation frequency selection range.

### Claim 20 (depends on 10)

The display device of claim 10, wherein the frequency randomizer comprises:
a total vertical line randomizer configured to randomly select a number of total vertical lines of frame data;
a total horizontal line randomizer configured to randomly select a number of total horizontal lines of frame data; and
a modulation frequency randomizer configured to randomly select the modulation frequency within a modulation frequency selection range, a reference modulation frequency being within the modulation frequency selection range.