WO2014191049A1 - Procédé de commande du rétro-éclairage d'un écran lcd - Google Patents

Procédé de commande du rétro-éclairage d'un écran lcd Download PDF

Info

Publication number
WO2014191049A1
WO2014191049A1 PCT/EP2013/061277 EP2013061277W WO2014191049A1 WO 2014191049 A1 WO2014191049 A1 WO 2014191049A1 EP 2013061277 W EP2013061277 W EP 2013061277W WO 2014191049 A1 WO2014191049 A1 WO 2014191049A1
Authority
WO
WIPO (PCT)
Prior art keywords
blue
green
backlight
lcd panel
color red
Prior art date
Application number
PCT/EP2013/061277
Other languages
English (en)
Inventor
Jacob Lerenius
Original Assignee
Huawei Technologies Co., Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Huawei Technologies Co., Ltd. filed Critical Huawei Technologies Co., Ltd.
Priority to PCT/EP2013/061277 priority Critical patent/WO2014191049A1/fr
Publication of WO2014191049A1 publication Critical patent/WO2014191049A1/fr

Links

Classifications

    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes 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 by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/3413—Details of control of colour illumination sources
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/02—Improving the quality of display appearance
    • G09G2320/0271—Adjustment of the gradation levels within the range of the gradation scale, e.g. by redistribution or clipping
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00—Control of display operating conditions
    • G09G2320/06—Adjustment of display parameters
    • G09G2320/0626—Adjustment of display parameters for control of overall brightness
    • G09G2320/0646—Modulation of illumination source brightness and image signal correlated to each other
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2360/00—Aspects of the architecture of display systems
    • G09G2360/16—Calculation or use of calculated indices related to luminance levels in display data

Definitions

  • the present invention relates to a method for controlling the backlight of a LCD panel. Furthermore, the invention also relates to a display device, a computer program, and a computer program product thereof.
  • LCD panels are common in handheld devices, such as mobile phones and tablet devices.
  • electricity to light seen by a user looking onto an LCD panel there are mainly three steps required, i.e.: converting the light from electricity, filtering the colors, and adjusting the intensity of the light in each sub-pixel in the LCD panel.
  • a white light with a broad spectrum is generated from a blueish LED covered with a phosphor layer. This light is then evenly distributed using a light guide and filtered into different intensity blue, red and green sub-pixels on the screen that makes up a pixel. The three sub-pixels are small enough to make the human eyes to see it as one dot with a particular color.
  • RGB red, green, blue
  • the light consists of three narrow peaks in the wavelength spectrum. Each of the three colors is generated by a single LED and no phosphor layer is used. By using narrow peaks, these can be adjusted to match that of the color filters.
  • the difference in efficiency between mentioned two systems is that in the latter system the colors can match the filters better, the conversion efficiency loss in the phosphor layer is not present, and a lower voltage can be used to drive the red LED.
  • CABC Content Adaptive Backlight Control
  • a highest value of the backlight pixel data is found. This highest value is then translated together with all the other pixels to the maximum brightness level.
  • a dynamic compression in the peak values or for the full range may also take place along with other image processing such as enhancement of the contrast.
  • the backlight intensity is translated down equally to compensate for the pixel translation. As pixels in a LCD panel consumes near equal amount of power independently of what is shown, the power saved when lowering the backlight level is significant.
  • An object of the present invention is to provide a solution which mitigates or solves the drawbacks and problems of prior art solutions.
  • Another object of the invention is to provide a backlight solution for LCD panels which reduces power consumption compared to prior art.
  • a method for controlling a backlight of a LCD panel for a display device said LCD panel being arranged to use a RGB backlight system, the method comprising the steps of:
  • CABC Content Adaptation Backlight Control
  • the method according to the present invention may be comprised in computer program having code means which when run by processing means executes the present method.
  • a display device comprising at least one LCD panel and at least one image processing unit, said LCD panel comprising at least one display section and being arranged to use a RGB backlight system, wherein the RGB backlight system is controlled by said image processing unit, wherein said image processing unit is arranged to
  • CABC Content Adaptation Backlight Control
  • Such a display device may be arranged in a mobile unit, such as a mobile phone or a tablet device or any other suitable mobile unit.
  • the device may also be modified according to the different embodiments of the present method. Further applications and advantages of the present invention will be apparent from the following detailed description.
  • Fig. 1 illustrates the present invention
  • Fig. 2 illustrates how the user interface can be adjusted with the use of the present invention
  • Fig. 3 shows a first flow chart according to an embodiment of the invention
  • - Fig. 4 shows a second flow chart according to an embodiment of the invention.
  • the present invention relates to a method for controlling a backlight of a LCD panel for a display device.
  • the LCD panel is arranged to use a RGB backlight system which is well known in the art.
  • the present method comprises the steps of applying the CABC algorithm separately on each of the colors red, green, and blue of the RGB backlight system, and thereafter adjusting the backlight of the LCD panel based on the three separate outputs from the CABC algorithm for each color red, green, and blue.
  • the CABC algorithm is applied simultaneously and in parallel for the three different colors for each frame.
  • RGB backlight and a CABC algorithm for each color channel is therefore proposed.
  • the LCD panel is one of the main consumers of energy in a mobile device
  • RGB backlight as well as implementing the present invention, the total power efficiency will be improved which e.g. means longer user times for the end consumer.
  • the potential power saving is large as the three channels can be optimized independently compared to prior art with the use of the present invention.
  • the image (frame) will be analyzed and adjusted together with the corresponding backlight for each color individually according to the invention.
  • the backlight of the corresponding color backlight contribution may be reduced accordingly.
  • the data from each sub-pixel is used together with the RGB backlight level control.
  • Each frame will analyzed based on the intensity data for each color and adjusted together with the corresponding backlight for each color individually.
  • Fig. 1 illustrates the present invention.
  • the steps of applying the CABC algorithm for each color and each image frame involves the steps of deriving a maximum pixel brightness of each color (red, green, and blue). Increasing a brightness of each color and decreasing the backlight of the LCD panel by the same ratio for each color. This embodiment is illustrated in the flow chart of fig. 3.
  • the step of increasing the brightness may according to another embodiment of the invention involve increasing the brightness of all pixels of each image frame until the brightest pixels has reached a maximum value.
  • the maximum value can be the maximum available brightness level for the used number of bits per color. This means that the LCD sub-pixel is open 100 %.
  • the step of deriving the maximum pixel brightness of each color is preceded by image preprocessing so as making the CABC algorithm as efficient as possible and also to further improving the performance of the present invention.
  • image preprocessing algorithms may in one alternative include dynamic compression.
  • the data is analyzed and the peak value is detected.
  • the peak value is detected.
  • the whole matrix of pixels for this color is translated to the maximum brightness and the backlight is than adjusted to a lower value accordingly.
  • the result is a pixel brightness that is the same as original frame but possibly with some dynamic range losses.
  • the preprocessing may however affect the image quality and may therefore have parameters to control the balance between power saving and quality. It is however possible to save power even without changing the quality. It is possible to increase the brightness of the image and lowering the backlight as long as the brightest pixel on the screen is not fully white.
  • the maximum pixel brightness for each color can be derived either directly or by applying a low-pass filter.
  • the actual maximum value can be used, or a value obtained by low pass filtering where for example the maximum value of the average between two or more adjacent pixels is used. This can be an option so that not only one single bright pixel will impact alone on the algorithm.
  • the above embodiment is illustrated in the flow chart of fig. 4.
  • the individual filtering and processing of the image data for the different colors of each frame is used to adopt the data to be able to save more energy in the system on the expense of dynamic range or contrast.
  • the amount of adjustment done will depend on what information is being shown and a general trade-off between power and quality.
  • anti-flicker compensation for each color is applied between each image frame. This will prevent flickering of the image due to fast changes of the backlight. If this is an optically visible issue when the backlight changes in large steps, an anti flickering function may be used to reduce the change between each frame.
  • UI User Interface
  • a red clock on the screen will only use the red LED backlight, powered at 2 V and matching the red filter exactly resulting in much lower power consumption compared with a solution using a white LED backlight and thus in this case keeping the LEDs at the maximum level set by the system.
  • Saving power in the UI is almost impossible with the while LED content adaptive backlight control as the contrast ratio is most often 100 % on one or more colors. See fig. 2 for an illustration of a UI which uses the present invention. In fig 2 only the green color of the three colors is used in the UI so as to reduce the power consumption. It is therefore realized that the design of the UI can be adjusted so as to take the full advantage of the present invention thereby increasing the power saving even more.
  • the invention may also be used in a system (display) using two or more separate sections where the backlight may be controlled independently for each section. This means that the present method is applied on each display section separately. If only one section displays bright data, the other sections do not have to adjust to the first section but can adjust according to the brightest pixel in its own section which saves power.
  • the present invention also relates to a display device comprising at least one LCD panel and at least one image processing unit.
  • the device comprises the means and is arranged to perform the present method.
  • the device may e.g. have at least one image processing unit arranged to control the RGB backlight system of the LCD panel.
  • the image processing unit is arranged to apply the CABC algorithm separately on each of the colors red, green, and blue of the RGB backlight system.
  • the unit is further arranged to adjust the backlight of the LCD panel based on the three separate outputs from the CABC algorithm for each color.
  • the present device has the same advantages as the present method. It should also be realized that the device can be modified, mutatis mutandis, according to the different embodiments of the present method.
  • the present device is preferably arranged in a mobile unit such as a mobile phone or a tablet device.
  • a mobile unit such as a mobile phone or a tablet device.
  • the method and device of the invention can also be used in stationary devices such as television and computer screens.
  • any method according to the present invention may also be implemented in a computer program, having code means, which when run by processing means causes the processing means to execute the steps of the method.
  • the computer program is included in a computer readable medium of a computer program product.
  • the computer readable medium may comprises of essentially any memory, such as a ROM (Read-Only Memory), a PROM (Programmable Read-Only Memory), an EPROM (Erasable PROM), a Flash memory, an EEPROM (Electrically Erasable PROM), or a hard disk drive. It is however noted that the present invention may also be implemented in dedicated hardware of suitable devices.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Liquid Crystal Display Device Control (AREA)

Abstract

La présente invention concerne un procédé de commande du rétro-éclairage d'un écran LCD destiné à un dispositif d'affichage, ledit écran LCD étant configuré pour utiliser un système de rétro-éclairage RGB, le procédé comportant les étapes consistant à: appliquer un algorithme de commande de rétro-éclairage avec adaptation au contenu, CABC, séparément sur chacune des couleurs rouge, verte et bleue du système de rétro-éclairage RGB; et régler le rétro-éclairage de l'écran LCD sur la base des trois sorties séparées issues de l'algorithme CABC pour chacune des couleurs rouge, verte et bleue. En outre, l'invention concerne également un dispositif d'affichage, un programme informatique et un produit de programme informatique associés.
PCT/EP2013/061277 2013-05-31 2013-05-31 Procédé de commande du rétro-éclairage d'un écran lcd WO2014191049A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
PCT/EP2013/061277 WO2014191049A1 (fr) 2013-05-31 2013-05-31 Procédé de commande du rétro-éclairage d'un écran lcd

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2013/061277 WO2014191049A1 (fr) 2013-05-31 2013-05-31 Procédé de commande du rétro-éclairage d'un écran lcd

Publications (1)

Publication Number Publication Date
WO2014191049A1 true WO2014191049A1 (fr) 2014-12-04

Family

ID=48626004

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2013/061277 WO2014191049A1 (fr) 2013-05-31 2013-05-31 Procédé de commande du rétro-éclairage d'un écran lcd

Country Status (1)

Country Link
WO (1) WO2014191049A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111210777A (zh) * 2018-11-21 2020-05-29 北京小米移动软件有限公司 背光亮度调整方法、装置、电子设备、机器可读存储介质

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1914713A1 (fr) * 2006-10-20 2008-04-23 Hitachi, Ltd. Dispositif d'affichage à cristaux liquides comprenant un éclairage coloré
US20090267926A1 (en) * 2008-04-29 2009-10-29 Samsung Electronics Co., Ltd. Method for driving light source blocks, driving unit for performing the method and display apparatus having the driving unit
US20100013872A1 (en) * 2007-06-11 2010-01-21 Takeshi Masuda Liquid crystal display device
WO2010150299A1 (fr) * 2009-06-22 2010-12-29 株式会社 東芝 Dispositif d'affichage à cristaux liquides
EP2299433A1 (fr) * 2008-07-03 2011-03-23 Sharp Kabushiki Kaisha Dispositif d'affichage d'image et procédé d'affichage d'image

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1914713A1 (fr) * 2006-10-20 2008-04-23 Hitachi, Ltd. Dispositif d'affichage à cristaux liquides comprenant un éclairage coloré
US20100013872A1 (en) * 2007-06-11 2010-01-21 Takeshi Masuda Liquid crystal display device
US20090267926A1 (en) * 2008-04-29 2009-10-29 Samsung Electronics Co., Ltd. Method for driving light source blocks, driving unit for performing the method and display apparatus having the driving unit
EP2299433A1 (fr) * 2008-07-03 2011-03-23 Sharp Kabushiki Kaisha Dispositif d'affichage d'image et procédé d'affichage d'image
WO2010150299A1 (fr) * 2009-06-22 2010-12-29 株式会社 東芝 Dispositif d'affichage à cristaux liquides

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111210777A (zh) * 2018-11-21 2020-05-29 北京小米移动软件有限公司 背光亮度调整方法、装置、电子设备、机器可读存储介质

Similar Documents

Publication Publication Date Title
CN105139809B (zh) 液晶显示亮度控制方法和装置以及液晶显示设备
CN105161064B (zh) 液晶显示亮度控制方法和装置以及液晶显示设备
CN105528994B (zh) 一种降低显示面板功耗的方法及系统
US8860657B2 (en) Liquid crystal display backlight control
CN105118474B (zh) 液晶显示亮度控制方法和装置以及液晶显示设备
CN107103886B (zh) 一种动态背光控制显示方法及装置
KR101093884B1 (ko) 동적인 백라이트 적응
US11335277B2 (en) Method, apparatus, and device for adjusting backlight brightness based on human eye characteristics
CN102122501B (zh) 红绿蓝白光显示系统的背光调整装置及其方法
CN108538260A (zh) 图像显示处理方法及装置、显示装置及存储介质
De Greef et al. 39.1: Adaptive Dimming and Boosting Backlight for LCD‐TV Systems
US9552781B2 (en) Content adaptive LCD backlight control
CN103430230B (zh) 视频显示装置
CN103456265A (zh) 选择性调暗从而减少发光显示装置的功率
KR102060604B1 (ko) 휘도 조절부, 이를 포함하는 표시 장치 및 이를 이용한 휘도 조절 방법
CN102737610A (zh) 一种光源亮度调整方法、装置及显示设备
CN101877208B (zh) 一种led背光源的控制方法
US8704844B2 (en) Power saving field sequential color
WO2013142067A1 (fr) Systèmes et méthodes de réduction de puissance iso-observable pour des affichages
CN104269149A (zh) 控制显示器的方法
CN105513543A (zh) 基于大屏lcm的图像处理方法及装置
CN101937652B (zh) 一种直下式白光led背光源背光计算方法
US9536478B2 (en) Color dependent content adaptive backlight control
WO2014191049A1 (fr) Procédé de commande du rétro-éclairage d'un écran lcd
Asnani et al. Producing green computing images to optimize power consumption in OLED-based displays

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 13728698

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 13728698

Country of ref document: EP

Kind code of ref document: A1