EP1684258A1 - Procédé et appareil pour afficher des images video sur un un panneau d'affichage à plasma - Google Patents

Procédé et appareil pour afficher des images video sur un un panneau d'affichage à plasma Download PDF

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Publication number
EP1684258A1
EP1684258A1 EP05290170A EP05290170A EP1684258A1 EP 1684258 A1 EP1684258 A1 EP 1684258A1 EP 05290170 A EP05290170 A EP 05290170A EP 05290170 A EP05290170 A EP 05290170A EP 1684258 A1 EP1684258 A1 EP 1684258A1
Authority
EP
European Patent Office
Prior art keywords
sub
fields
phosphor
field
image
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP05290170A
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German (de)
English (en)
Inventor
Didier c/o Thomson Doyen
Emmanuel c/o Thomson Jolly
Jonathan c/o Thomson Kervec
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Thomson Licensing SAS
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Thomson Licensing SAS
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Filing date
Publication date
Application filed by Thomson Licensing SAS filed Critical Thomson Licensing SAS
Priority to EP05290170A priority Critical patent/EP1684258A1/fr
Publication of EP1684258A1 publication Critical patent/EP1684258A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • G09G3/22—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 using controlled light sources
    • G09G3/28—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 using controlled light sources using luminous gas-discharge panels, e.g. plasma panels
    • 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
    • G09G3/2003—Display of colours
    • 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
    • G09G2320/0242—Compensation of deficiencies in the appearance of colours
    • 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
    • G09G2320/0257—Reduction of after-image effects
    • 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
    • G09G3/2007—Display of intermediate tones
    • G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
    • G09G3/2022—Display of intermediate tones by time modulation using two or more time intervals using sub-frames
    • G09G3/2033—Display of intermediate tones by time modulation using two or more time intervals using sub-frames with splitting one or more sub-frames corresponding to the most significant bits into two or more sub-frames

Definitions

  • the present invention relates to a method and an apparatus for displaying on a plasma display panel. This method is particularly adapted for compensating the phosphor lag.
  • the plasma display technology makes it possible now to achieve flat colour displays of large size with limited depth.
  • This technology gives the possibility of "unlimited” screen size with limited thickness, but generates new kinds of artifacts.
  • One of these artifacts called “phosphor lag" is due to the difference of time responses of the different phosphors used in the plasma display panels (PDPs) for producing colored light (Red, Green, Blue).
  • PDPs plasma display panels
  • Each of the three colored lights is generated by the same electrical excitation of a gas.
  • This excitation provides some UV rays, which will strike the front plate where a layer of phosphor has been deposited.
  • Figure 1 shows the time response of the three phosphors after switching on and off one pixel.
  • the first diagram of figure 1 represents the drive voltage applied to three cells with different phosphors (blue, red, green) and the second diagram shows the light response of these cells.
  • the blue cell the rising and especially falling times of light emission of the red cell and the green cell are much longer, which results in the emission of blue light before red and green lights. Due to the integration ability of the human eye, this effect will be masked if the picture is stationary and the perceived color is only white. In case of a moving object like a white rectangle on a black background, the phosphor lag becomes visible and a blue and a yellow-green edge appears.
  • the gravity center of the red, green and blue curves of the figure 1 can be moved in order to be at the same temporal place. Such an operation is shown at figure 2.
  • the gravity center of a curve means the time where half of the light energy is emitted.
  • the blue curve is shifted so that its gravity center matches the gravity centers of the two others.
  • the invention proposes another solution for phosphor lag compensation.
  • the invention concerns a method for displaying a sequence of video images on a plasma display panel comprising a plurality of elementary cells each including one type of phosphor from among at least two types of phosphors (blue, green, red) homogeneously distributed in the display panel, the display of a video image taking place for a display period divided by a plurality of sub-fields during which each elementary cell emits or does not emit coloured light according to the type of phosphor with which it is associated, characterized in that different groups of sub-fields are used for displaying a video image for at least two types of phosphor.
  • At least one sub-field of the plurality of sub-fields of the display period of a video image is used by only one type of phosphor.
  • this (these) sub-field(s) is (are) the one(s) with the highest durations of the display period. If the phosphor using this (these) sub-field(s) is the phosphor having the highest time response, this (these) sub-fields(s) is (are) placed at the end of the display period. For example, if the blue phosphor is the type of phosphor having the highest time response, at least one of the last sub-fields in the display period will be used only by this phosphor.
  • the sub-fields used for displaying a current video image are, for a first part, sub-fields used by the other types of phosphor for displaying the current image and, for a second part, sub-fields used by the other types of phosphor for displaying the image preceding or following the current image.
  • the sub-fields of the second part are sub-fields with the highest durations of the display period. If the type of phosphor having said first and second parts of sub-fields is the type of phosphor having the highest time response, the sub-fields of the second part are the sub-fields of the display period of the video image following the current image which are placed at the end of this display period.
  • the invention also relates to a plasma display panel for displaying a sequence of video images comprising :
  • the image processing means comprise sub-field encoding means for encoding a current video image into sub-field code and time shifting means for shifting a part of the sub-field code of at least one color component of the image associated to one type of phosphor and activating dedicated sub-fields of the plurality of sub-fields of the display period, said dedicated sub-field being used only by said color component.
  • the image processing means comprise sub-field encoding means for encoding a current video image into sub-field code, a sub-field memory for storing a part of the sub-field code of at least one color component of the current image associated to one type of phosphor and time shifting means for reintroducing it in the sub-field code of the next picture.
  • the invention concerns also a device implementing the above-mentioned method.
  • the best way to superpose the gravity center of the three color components of the video signal is to apply a delay to the component(s) with the highest time response compared with the other color component(s).
  • the invention will be described for a panel where green and red phosphors have similar temporal characteristics and where blue has a higher time response compared with the red and green color components.
  • the principle of the invention is to use different sub-field coding schemes for the color components.
  • the invention takes into account the fact that the phosphor lag is due for a big part to the position of the high level sub-fields (high duration sub-fields). These sub-fields are the ones, which are "shifted" according to the invention.
  • some specific sub-fields are added in the video frame (display period) and are dedicated to phosphor lag compensation.
  • a new coding scheme using these specific sub-fields is defined.
  • the number of the added sub-fields depends on the delay to be applied. In reference to Figure 3B to be compared to Figure 3A, 3 specific sub-fields are added. This number of sub-fields seems to be the minimum for the actual panels.
  • the 3 color components are coded with a classical 12 sub-fields code.
  • the sub-fields have the following weights: 1 2 4 8 16 32 32 32 32 32 32 32 32 32
  • the red and green components are also coded with this classical 12 sub-fields code and the blue component is coded on 15 sub-fields : the 12 sub-fields of the classical code and 3 specific 32 weighted sub-fields dedicated to phosphor lag compensation and placed at the end of the frame.
  • the three first 32 weighted sub-fields are always off for the blue component and the three final 32 weighted sub-fields are always off for the two other colour components.
  • Simulations show that there is no additional false contour due to the "holes" created in the blue coding scheme by the 3 first weighted sub-fields OFF.
  • Another advantage of this method is that it is possible to shift one or more colour components of the video signal and, if several components are shifted, to shift them differently.
  • FIG 4 shows the block diagram of a plasma display panel implementing the method illustrated by Figure 3B.
  • a 8-bit video signal (one for each colour) is inputted to image processing means 10. It includes a sub-field encoding block 11 for coding the 8-bit video signal into a 12-bit video signal (one bit for each sub-field) and a time shifting block 12 for converting the 12-bit signal into 15-bit video signal so as to shift the blue component (more particularly the highly weighted sub-fields of the blue component) as shown by figure 3B.
  • This signal is then transmitted to the drivers13 of the display panel. Then the drivers 13 generate control signals for driving the state of the cells of the cells 14 of the PDP.
  • This method does not need motion estimator or additional memory. Furthermore, it can be possible to use the specific sub-fields for increasing the luminance of the display panel for the static images.
  • a classical coding scheme is used for all color components but the video information of the blue component is spread on two successive frames.
  • Figures 5A and 5B show a transition for all color components between a video level 255 and a video level 61 on two successive frames N and N+1. These two levels are coded with a classical 12-sub-fields code. The sub-fields used have the same weights as those given in figure 3A. In figure 5B, these levels are coded with this classical 12-sub-fields code using a split coding.
  • the sub-fields used for displaying a current video image are, for a first part, sub-fields used by the red and green components for displaying the current image and, for a second part, sub-fields used by the red and green components for displaying the next image in the image sequence to be displayed.
  • some sub-fields used for displaying red and green video information of frame N+1 are used for displaying blue video information of the frame N.
  • the sub-fields of the frame N are used for displaying the level 255 and the sub-fields of the frame N+1 are used for displaying the level 61.
  • some sub-fields (32-weighted sub-fields) of frame N+1 are used for displaying the level 255. Consequently, the level 255 is displayed for a part (sub-fields with weights 1, 2, 4, 8, 16 and four 32-weighted sub-fields) during the frame N and for a second part (three 32-weighted sub-fields) during the frame N+1.
  • the three first 32-weighted sub-fields of the frame N are used for displaying a part of the blue video information of the frame N-1.
  • the displaying of the blue video information associated to the 32-weighted sub-fields is shifted three 32-weighted sub-fields forward.
  • the first 32-weighted sub-field for displaying the level 61 is shifted three 32-weighted sub-fields forward.
  • This split coding scheme is applied on the high level sub-fields. That means that a sub-field bit plan memory should be provided in the display panel for storing the second part of the sub-field codes of the current video image.
  • a sub-field bit plan memory should be provided in the display panel for storing the second part of the sub-field codes of the current video image.
  • the code of the three last 32 weighted sub-fields are stored to be used as the three first 32-weighted sub-fields of the frame N+1.
  • the depth of this extra memory depends on the delay to apply to the blue component (3 sub-fields seems to be the minimum).
  • 3-bit data should be stored for each pixel of the picture to be displayed.
  • One critical case, illustrated by figure 6, could be the case of a 255 to 0 transition where there is no activated 32 weighted sub-fields for the green and red components in the next frame and no activated low weighted sub-fields for the blue component. There is a "hole" in the blue light emission between the last 32-weighted subfield of frame N and the first 32-weighted subfield of frame N+1 but it creates few false contours. But, in most cases, this high transition is quite unusual in video domain and at least one low weighted sub-field in the frame N+1 is activated.
  • FIG. 7 shows a block diagram of a plasma display panel implementing the method illustrated by Figure 5B.
  • a 8-bit video signal (one for each colour) is inputted to image processing means 20. It includes a sub-field encoding block 21 for coding it into a 12-bit video signal (one bit for each sub-field), a . sub-field memory 23 and a time shifting block 22.
  • the bit associated to the three last 32-weighted sub-field in the 12-bit video signal of the current image are stored in the sub-field memory 23 and introduced in the next image as shown in figure 5B by the time shifting block 22.
  • the video signal thus processed is then transmitted to the drivers 24 of the display panel for controlling the cells 25 of the panel.
  • This second embodiment does not need motion estimator or specific sub-fields for compensating the phosphor lag.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
EP05290170A 2005-01-25 2005-01-25 Procédé et appareil pour afficher des images video sur un un panneau d'affichage à plasma Withdrawn EP1684258A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP05290170A EP1684258A1 (fr) 2005-01-25 2005-01-25 Procédé et appareil pour afficher des images video sur un un panneau d'affichage à plasma

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Application Number Priority Date Filing Date Title
EP05290170A EP1684258A1 (fr) 2005-01-25 2005-01-25 Procédé et appareil pour afficher des images video sur un un panneau d'affichage à plasma

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EP1684258A1 true EP1684258A1 (fr) 2006-07-26

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EP05290170A Withdrawn EP1684258A1 (fr) 2005-01-25 2005-01-25 Procédé et appareil pour afficher des images video sur un un panneau d'affichage à plasma

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2242035A1 (fr) * 2009-04-17 2010-10-20 Thomson Licensing Réduction des artéfacts de délai du phosphore sur des dispositifs d'affichage

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002014647A (ja) * 2000-06-28 2002-01-18 Fujitsu Hitachi Plasma Display Ltd 表示パネルの駆動方法および駆動装置
EP1288899A1 (fr) * 2001-08-23 2003-03-05 Thomson Licensing S.A. Procédé et appareil pour le traitement d'images vidéo
EP1291835A1 (fr) * 2001-08-23 2003-03-12 Deutsche Thomson-Brandt Gmbh Procédé et appareil pour le traitement d'images vidéo
EP1361558A1 (fr) * 2002-05-07 2003-11-12 Deutsche Thomson Brandt Réduction des artefacts des images le temps de réponse des phosphores d'un dispositif d'affichage
EP1361559A1 (fr) * 2002-05-07 2003-11-12 Thomson Licensing S.A. Réduction des artefacts des images d'un dispositif d'affichage causé par le temps de réponse des phosphores
JP2004138940A (ja) * 2002-10-21 2004-05-13 Matsushita Electric Ind Co Ltd 画像信号処理装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2002014647A (ja) * 2000-06-28 2002-01-18 Fujitsu Hitachi Plasma Display Ltd 表示パネルの駆動方法および駆動装置
EP1288899A1 (fr) * 2001-08-23 2003-03-05 Thomson Licensing S.A. Procédé et appareil pour le traitement d'images vidéo
EP1291835A1 (fr) * 2001-08-23 2003-03-12 Deutsche Thomson-Brandt Gmbh Procédé et appareil pour le traitement d'images vidéo
EP1361558A1 (fr) * 2002-05-07 2003-11-12 Deutsche Thomson Brandt Réduction des artefacts des images le temps de réponse des phosphores d'un dispositif d'affichage
EP1361559A1 (fr) * 2002-05-07 2003-11-12 Thomson Licensing S.A. Réduction des artefacts des images d'un dispositif d'affichage causé par le temps de réponse des phosphores
JP2004138940A (ja) * 2002-10-21 2004-05-13 Matsushita Electric Ind Co Ltd 画像信号処理装置

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 2002, no. 05 3 May 2002 (2002-05-03) *
PATENT ABSTRACTS OF JAPAN vol. 2003, no. 12 5 December 2003 (2003-12-05) *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2242035A1 (fr) * 2009-04-17 2010-10-20 Thomson Licensing Réduction des artéfacts de délai du phosphore sur des dispositifs d'affichage
US8520151B2 (en) 2009-04-17 2013-08-27 Thomson Licensing Reduction of phosphor lag artifacts on display devices

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