Display device and method for controlling panel self refresh operation thereof

Patent metadata

Field	Value
Publication number	US-9704215-B2
Application number	US-201213719459-A
Country	US
Kind code	B2
Filing date	Dec 19, 2012
Priority date	Mar 9, 2012
Publication date	Jul 11, 2017
Grant date	Jul 11, 2017

Abstract

A display device includes a source unit; and a sink unit connected with the source unit via an embedded display port interface for signal transmission between the source and sink units and to enable a panel self refresh (PSR) mode for reducing power, wherein, for an input still image, the source unit applies power to a frame buffer of the sink unit and transmits the still image to the sink unit, wherein the sink unit determines whether the still image can be losslessly compressed and stored in the frame buffer, outputs a first control signal if the still image can be losslessly compressed and stored in the frame buffer, and outputs a second control signal if the still image cannot be losslessly compressed and stored, and wherein the source unit activates the PSR mode for the first control signal, and deactivates the PSR mode for the second control signal.

First claim

What is claimed is:

1. A display device, comprising:
a source including an embedded display port (eDP) transmitter; and
a sink including a display portion, the sink operatively connected with the source via an eDP interface to provide signal transmission between the source and the sink and to enable a panel self refresh (PSR) mode for reducing power consumption,
wherein, in response to an input image being a still image, the source applies operating power to a frame buffer of the sink and transmits data of the still image to the sink,
wherein the sink losslessly compresses the data of the still image and determines the size of the compressed data,
wherein the sink:
determines whether or not the compressed data of the still image has a size that can be stored in the frame buffer by comparing the size of the compressed data of the still image with a predetermined size of the frame buffer,
outputs a first control signal to the source if the compressed data of the still image has a size that can be stored in the frame buffer, based on the comparing of the size, and
outputs a second control signal to the source if the compressed data of the still image has a size that cannot be stored in the frame buffer, based on the comparing of the size,
wherein the source:
receives one of the first and second control signals from the sink,
activates the panel self refresh mode in response to the first control signal, and
deactivates the panel self refresh mode in response to the second control signal,
wherein the source activates the panel self refresh mode when the size of the compressed data of the still image is less than or equal to the size of the frame buffer,
wherein the source deactivates the panel self refresh mode when the size of the compressed data of the still image is greater than the size of the frame buffer,
wherein the sink further includes:
a lossless capability determiner to determine whether or not the compressed data can be stored in the frame buffer by comparing a size of an address to store the compressed data with a predetermined maximum address size of the frame buffer;
a compressor to losslessly compress the data of the still image by a lossless compression algorithm; and
a recoverer to be enabled when the panel self refresh mode is activated, and to recover the compressed data stored in the frame buffer, and
wherein, if the panel self refresh mode is deactivated:
the sink turns off the operating power for elements that perform the panel self refresh mode, the elements including the compressor, the frame buffer, and the recoverer.

2. The display device of claim 1 , wherein the frame buffer has a smaller size than a size required to store information of one frame of the still image in an uncompressed format without loss.

3. The display device of claim 1 , wherein:
if the panel self refresh mode is activated, the operating power of the source is turned off; and
the sink stores the compressed data of the still image in the frame buffer, and recovers the compressed data stored in the frame buffer and applies the same to the display portion for image display when the operating power of the source is off.

4. The display device of claim 3 , wherein, if the panel self refresh mode is deactivated:
the sink applies the data of the still image input from the source to the display portion for image display without the compression, storage, and recovery processes; and
the source does not re-try the panel self refresh mode on such data that the sink determines cannot be losslessly compressed and stored.

5. The display device of claim 1 , wherein the sink further comprises:
a PSR controller to control whether to activate the panel self refresh mode or not by comparing the size of the compressed data of the still image, compressed by the lossless compression algorithm, with the predetermined size of the frame buffer.

6. The display device of claim 5 , wherein the PSR controller comprises:
an address generator to generate the address to store the data compressed by the lossless compression algorithm in the frame buffer; and
the lossless capability determiner.

7. A method for controlling a panel self refresh (PSR) operation of a display device which provides signal transmission between a source unit and a sink unit via an embedded display port (eDP) interface and enables a panel self refresh mode for reducing power consumption, the method comprising:
analyzing an input image;
in response to an input image being determined to be a still image in the analysis of the input image, applying operating power to a frame buffer of the sink unit and transmitting data of the still image from the source unit to the sink unit;
losslessly compressing the data of the still image and determining the size of the compressed data;
determining whether or not the compressed data of the still image has a size that can be stored in the frame buffer by comparing the size of the compressed data of the still image with a predetermined size of the frame buffer;
outputting a first control signal to the source unit if the compressed data of the still image has a size that can be stored in the frame buffer, based on the comparing of the size;
outputting a second control signal to the source unit if the compressed data of the still image has a size that cannot be stored in the frame buffer, based on the comparing of the size; and
activating the panel self refresh mode in response to the first control signal from the sink unit; and
deactivating the panel self refresh mode in response to the second control signal,
wherein the source unit activates the panel self refresh mode when the size of the compressed data of the still image is less than or equal to size of the frame buffer,
wherein the determination of whether or not the data of the still image can be losslessly compressed and stored in the frame buffer includes:
generating an address to store the data compressed by the lossless compression algorithm in the frame buffer, and
determining whether or not the compressed data can be stored in the frame buffer by comparing the size of the current generated address with a predetermined maximum address size of the frame buffer, and
wherein, if the panel self refresh mode is deactivated, the sink unit turns off the operating power for elements that perform the panel self refresh mode, the elements including:
the frame buffer;
a compressor to losslessly compress the data of the still image by a lossless compression algorithm; and
a recoverer to be enabled when the panel self refresh mode is activated, and to recover the compressed data stored in the frame buffer.

8. The method of claim 7 , wherein the frame buffer has a smaller size than a size required to store information of one frame of the still image in an uncompressed format without loss.

9. The method of claim 7 , wherein:
if the panel self refresh mode is activated, the operating power of the source unit is turned off; and
the sink unit stores the compressed data of the still image in the frame buffer, and recovers the compressed data stored in the frame buffer and applies the same to the display portion for image display when the operating power of the source unit is off.

10. The method of claim 9 , wherein, if the panel self refresh mode is deactivated, the sink unit applies the data of the still image input from the source unit to the display portion for image display without the compression, storage, and recovery processes, and the source unit does not re-try the panel self refresh mode on such data that the sink unit determines cannot be losslessly compressed and stored.

Assignees

• Lg Display Co Ltd

Inventors

• Kim Jinsung
• Hong Jincheol
• Kim Minki

Classifications

• G09G2360/18

  Use of a frame buffer in a display terminal, inclusive of the display panel · CPC title

• G09G5/006 Primary

  Details of the interface to the display terminal (specific for a display terminal using a CRT G09G1/167; using a flat panel G09G3/2096; circuits for interfacing with colour displays G09G5/04) · CPC title

• G09G2320/103

  Detection of image changes, e.g. determination of an index representative of the image change · CPC title

• G09G2370/045

  using multiple communication channels, e.g. parallel and serial · CPC title

• G09G5/363

  Graphics controllers · CPC title