EP2097893A1 - Method for addressing an lcd display in colour sequential mode - Google Patents

Method for addressing an lcd display in colour sequential mode

Info

Publication number
EP2097893A1
EP2097893A1 EP07857922A EP07857922A EP2097893A1 EP 2097893 A1 EP2097893 A1 EP 2097893A1 EP 07857922 A EP07857922 A EP 07857922A EP 07857922 A EP07857922 A EP 07857922A EP 2097893 A1 EP2097893 A1 EP 2097893A1
Authority
EP
European Patent Office
Prior art keywords
color
display
sequence
colored
random
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.)
Granted
Application number
EP07857922A
Other languages
German (de)
French (fr)
Other versions
EP2097893B1 (en
Inventor
Maxime Vaillant
Patrick Rocca
Hugues Lebrun
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
Original Assignee
Thales SA
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Filing date
Publication date
Application filed by Thales SA filed Critical Thales SA
Publication of EP2097893A1 publication Critical patent/EP2097893A1/en
Application granted granted Critical
Publication of EP2097893B1 publication Critical patent/EP2097893B1/en
Not-in-force legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control 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
    • G09G3/34Control 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
    • G09G3/3406Control of illumination source
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00Command of the display device
    • G09G2310/02Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0235Field-sequential colour display
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/0242Compensation of deficiencies in the appearance of colours
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2320/00Control of display operating conditions
    • G09G2320/02Improving the quality of display appearance
    • G09G2320/0261Improving the quality of display appearance in the context of movement of objects on the screen or movement of the observer relative to the screen
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control 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
    • G09G3/34Control 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
    • G09G3/3406Control of illumination source
    • G09G3/3413Details of control of colour illumination sources
    • GPHYSICS
    • G09EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09GARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20Control 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
    • G09G3/34Control 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
    • G09G3/36Control 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 using liquid crystals
    • G09G3/3607Control 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 using liquid crystals for displaying colours or for displaying grey scales with a specific pixel layout, e.g. using sub-pixels

Definitions

  • the present invention relates to a liquid crystal display of the sequential color addressing type, and more particularly to a method of addressing such a display. It is particularly applicable to the full range of direct view displays, ranging from cell phone screens to large screens for television.
  • color sequential displays An interest of color sequential displays is the possibility of producing color display systems for direct vision screens without color filters, that is to say without color information attached to an image point (pixel).
  • image point Each image point is colorless and a light box is used which successively illuminates the display in the three primary colors, typically red, green and blue.
  • the addressing then comprises several color frames per complete video frame. In the time of each color frame, all the pixels of the matrix are addressed to display the video information corresponding to the associated primary color, and the light box illuminates the display in the corresponding primary color.
  • FIG. 1 A corresponding color sequence is illustrated in FIG. 1:
  • F1 for example, there are three colored fields, red, green and blue, in the example fRi, fd and f ⁇ 1, respectively.
  • the red, green, blue color sequence is repeated periodically at the frequency of the complete video frames.
  • the frame rate is 60Hz giving a TO duration of 16.667ms for each video frame.
  • a known problem of these displays is the so-called color break-up problem, due to the stabilization time of the liquid crystal, which results in a noticeable display defect for the eye of an observer. Indeed, because of the ability of the eye to distinguish very fast movements, it is able to distinguish the succession of different colored frames. In particular, an observer perceives Particularly visible color flashes on a white image when the screen is operating at low frequency or when moving the head in front of the screen. While the eye accepts without being too embarrassed a complete refresh of the images at 50Hz, a color change at the frequency of 150Hz can be detected in cases of observation such as those mentioned above.
  • the perception by the eye of this display defect takes the form of a succession of bands or colored fringes, typically the succession of primary colors, as illustrated schematically in Figure 1, with a spatial frequency which depends on the frequency of refresh the image.
  • the eye perceives a periodic succession of a red band, a green band, and a blue band.
  • the invention relates to a method for addressing a color sequential liquid crystal display, from a video sequence of successive color frames, which comprises a step of random or pseudo-random arrangement of said colored fields of said sequence.
  • video for providing a sequence of display of color frames to be applied to said display, said random arrangement comprising a random or pseudo-random arrangement of the display order of said color frames, and / or a random or pseudo-random assignment duration of each of said colored fields.
  • said random arrangement is such that said display sequence comprises a succession of packets of n colored frames, n being at least equal to 3, each packet being associated with a pair of primary colors, comprising a first primary color and a second primary color, the odd-rank colored fields in a packet being color fields corresponding to said first color, the even-rank colored fields in the packet being colored fields corresponding to said second color.
  • the power level of light emitted in the lighting phase of a colored frame is advantageously random.
  • the light power level of each colored frame is such that the light power reconstituted on the display corresponds to an achromatic white.
  • the invention also relates to a liquid crystal display of the sequential color addressing type, comprising an addressing device implementing an addressing method according to the invention.
  • FIG. 1 already described illustrates a colored sequence according to the state of the art
  • FIG. 2 already described illustrates the phenomenon of cleavage of colors as perceived by the eye of an observer
  • FIG. 3 illustrates a sequence of colored frames constituted by a addressing method according to the invention
  • FIG. 4 illustrates a display with an addressing device for implementing a method according to the invention
  • FIG. 5 illustrates a sequence of colored fields according to a first embodiment of the invention
  • FIG. 6 illustrates a sequence of colored fields according to a variant of the first embodiment
  • FIG. 7 illustrates a sequence of colored fields according to a second embodiment of the invention
  • FIG 8 is a general block diagram of a method of addressing an LCD display according to the invention.
  • cyan blue Bc is represented in dark gray, purple M in light gray and yellow Y in medium gray.
  • FIGS. 3 and 4 illustrate an addressing method according to the invention, in which the colored frames of a video sequence SV are arranged randomly or almost randomly to constitute a display sequence SD of colored frames applied to a display 1
  • This random or pseudo-random arrangement according to the invention applies to the order of display of the colored fields on the display 1, and / or to the duration of each of the colored fields.
  • the display sequence SD constituted according to the invention comprises a series of colored frames fRi, fd, fBi, fG2, fB2, fR2, fG3, fR3, fB3, corresponding to a random succession of the primary colors according to the sequence RGBGBRGRB , each corresponding colored frame having a specific duration, chosen randomly, in the example tii, tg1, tb1, tg2, tb2, tr2, tg3, tr3, tb3 ..., respectively.
  • a complete frame of a color video image to be displayed comprises three successive color video frames, always in the same order, typically a red video frame, then green then blue.
  • An addressing device processes the complete video frames with their color video frames presented in order on the display. For each color video frame, the addressing device reads the corresponding data to be displayed to control the pixels of the array in an appropriate write phase, and the array is illuminated in the corresponding primary color.
  • the display device arranges the color video frames of one or more complete video frames to form an SD sequence of color frames in which the primary colors occur in random sequence, and / or which the durations of the colored frames are random.
  • Fk (k integer) the complete video frames transmitted by an input signal of a video sequence SV, containing the images to be displayed.
  • FRk, fGk, fBk are the red, green, blue video frames of a video frame Fk of the video sequence SV.
  • a display device constitutes a display sequence SD applied to the display 1, from the colored fields of the received video sequence.
  • This constitution of an SD display sequence according to the invention consists in presenting the color video frames in a random order and / or in assigning them a frame time, or duration, random.
  • the display sequence SD according to the invention can be performed as described below.
  • a video signal to be displayed is received in the form of an SV video sequence of video frames.
  • the display device 10 comprises means
  • an SD display sequence of colored fields for example the SD sequence described in FIG.
  • k successive video frames F1 to Fk (k nonzero integer) of the sequence are stored for example in a buffer 12 fed by the incoming signal SV, to allow the constitution of a sequence display according to the invention.
  • the buffer memory is fed by 4 successive video frames, F1 to F4, which respectively comprise the following color frames: fRi, fGi, f ⁇ 1 for F1, fR2, fG2, fB2 for F2, fR3, fG3 , fB3 for F3, fR4, fG4, fB4 for F4.
  • the display sequence SD can be constituted as filling of the input buffer 12 by the frames of the video sequence SV, and it can itself be stored as a buffer buffer 13 as illustrated, or supply directly to a control device 14 of the LCD display 1.
  • the colored fields of the display sequence SD are thus successively displayed on the LCD display 1.
  • the light box 2 is controlled synchronously to illuminate the LCD display in correspondence with the display of the current colored frame of the SD sequence, during the frame time allocated to this colored frame, which can be fixed or random according to the implementation of the invention.
  • each packet of three colored fields of the display sequence SD corresponds to the colored fields of a video frame Fk of the video sequence SV, but presented in a random order with respect to their natural order in the sequence original SV video, and / or being each associated with a random frame time.
  • the means 1 1 constituting the display sequence SD take the first complete video frame F1 of the video sequence SV stored in the buffer memory, and constitute a first packet p1 of the SD sequence by drawing a random order of display of the three color frames fRi, fGi, f ⁇ 1 of this video frame F1; then the means 1 1 pass to the next complete video frame F2, to form a second packet p2 with its colored frames fR2, fG2, f ⁇ 2 ... and so on.
  • the display sequence SD thus consists of the sequence of packets p1, p2, ...
  • the invention is not limited to this embodiment of an SD display sequence. More generally, the display sequence SD can be constituted from the colored fields of one or more video frames Fk. Such embodiments of a display sequence SD from the color frames of several frames F1 to Fk of an input video sequence SV are illustrated in particular in FIGS. 5 and 6.
  • the buffer memory input 12 will contain at least k frames from which will be constituted a sequence of packets of the display sequence.
  • the implementation of the invention must meet different constraints, to fully produce all its effects and not degrade the performance of the display. In particular, three constraints must be taken into account:
  • the duration of a colored frame of the display sequence SD must be sufficiently small so as not to mark the eye of an observer in a lasting manner.
  • the duration of a colored frame of the display sequence SD must not be too short to be compatible with the performance of the liquid crystal on the active matrix. In particular, it must be greater than the stabilization time of the liquid crystal, a typical value of which is of the order of a millisecond. the color balance must be preserved to obtain an achromatic white. Typically, this is achieved with a light power reconstituted on the display including 60% green, 20% red and 20% blue.
  • the first two constraints impose an interval of possible values for the colored field times, with a minimum value T m ⁇ n (second constraint) and a maximum value T max (first constraint).
  • T m ⁇ n second constraint
  • T max first constraint
  • the implementation of the invention thus presupposes the implementation of random rules with color selection constraints and / or frame times, which will give the mechanism for arranging the colored frames of the video sequence received SV to form the sequence of SD display according to the invention.
  • the control mode of the level of The luminous power of the light box is such that the luminous power reconstituted on the display corresponds to an achromatric white.
  • Figures 5 to 7 illustrate examples of implementations of pseudo-random arrangements according to the invention, in which a pseudo-random succession of colors is obtained. These examples are not limiting.
  • the SD display sequences given in examples are formed from the SV input video sequence illustrated in FIGS. 1 and 4.
  • the display sequence SD of frames stained according to the invention is constituted in such a way that the color breaks advantageously occur in the secondary colors yellow Y (green + yellow), red magenta M (blue + red), or blue cyan Bc (blue + green) . These breaks in the secondary colors are less noticeable for the eye of an observer than the primary color breaks.
  • FIG. 5 illustrates a corresponding first embodiment.
  • two successive packets are associated with a different pair of primary colors.
  • the color of the n-rank colored frame of a packet of the display sequence SD and the color of the rank 1 colored frame of the next packet of said sequence are different.
  • a succession of 3 color frames is selected on the basis of a pair of first and second primary colors selected from six possible pairs (R 1 G), (G, R), (G 1 B), (B 1 G), (R 1 B) or (B, R).
  • the pair (R, G) is associated with the packet p1, the first color R of the pair giving the color of the first and the third of the three colored fields of the packet p1, and the second color G giving the color of the second colored frame of the packet.
  • the means 11 will then select corresponding color frames in the video sequence SV, according to their order of chronological appearance and according to the desired colors, which gives in the example for the packet p1 for the first colored frame, fRi, for the second colored field, fd, and for the third colored field, fR2.
  • the following packets p2, p3 of the subsequence are constituted according to the same principle: in the example, the second packet p2 corresponds to the selection of the pair of primary colors (B, R) and is constituted with fBi frames, fR3 and fB2 of the SV sequence, associated with this color selection.
  • the third packet p3 corresponds to the selection of the primary color pair (G, B) and is constituted with the frames fG2, fB3 and fG3 of the sequence SV, associated with this selection of colors.
  • the succession of colors imposed by the selection of pairs are constituted according to the same principle: in the example, the second packet p2 corresponds to the selection of the pair of primary colors (B, R) and is constituted with fBi frames, fR3 and fB2 of the SV sequence, associated with this color selection.
  • the third packet p3 corresponds to the selection of the primary color pair (G, B) and is constituted with the frames fG2,
  • the random pattern constituted in the example is the following: RGRGBRBRBGBG.
  • FIGS. 5 and 6 The embodiment of the invention which has just been described in relation to FIGS. 5 and 6 has the advantage of allowing a simple practical implementation, requiring limited memory means.
  • Fig. 7 illustrates another embodiment of a display sequence SD according to the invention from the input video sequence SV.
  • use is advantageously the spatial periodicity of the phenomenon of rupture of the primary colors to remove, an order of magnitude of the spatial frequency to be used is 10 ⁇ eme 100 ⁇ eme, millimeters or centimeters.
  • the colored fields are arranged in such a way that during the time of the colored frame in first position in each packet p1, p2 and p3, there is red for one frame, green for another and blue for another, or globally a white W. This is reproduced for each color frame position of the packets, c ' ie the second positions and the third positions. This removes the effect of spatial periodicity of the colors. In the illustrated example, there are thus in positions 1 st successively red, green and blue, in two positions ⁇ emes, green, blue and red and in positions 3 ⁇ emes, blue, red and green .
  • the display sequence SD may advantageously be formed by repetition of a random pattern, which is here given by the succession of colors on the sequence of the three successive packets p1 to p3, either: RGBGBRBRG. This random pattern is then repeated from one subsequence to another; SD- t, SD 2 , ...
  • Each display sub-sequence can advantageously be constituted from the colored fields of 3 successive complete video frames of the video sequence SV, such as F1, F2, F3.
  • the SD sequence is thus formed by periodic repetition of a random pattern, for example all 9 colored fields (FIGS. 5 and 7) or all 12 colored fields (FIG. 6)
  • a constraint on the frequency of repetition of the random pattern must be applied, in order to avoid flicker or flicker effects: the frequency of repetition of the random pattern must be higher than the frequency for which this flicker appears, a frequency which is noted ff ⁇ c ker-
  • an arrangement of the display sequence SD from the video sequence SV according to the invention comprises an allocation of a random duration (frame time) to each of the colored fields of the sequence.
  • a random duration frame time
  • the colored fields can be chained completely randomly in the SD display sequence.
  • the preceding constraints are written a little differently for the color balance. This is particularly the case in displays whose addressing method is based on a breakdown of the characteristic time of each frame color frame in three periods:
  • FIG. 8 gives a general overview of an addressing method with an arrangement step 100 of the colored frames according to the invention: after a parameterization 100.1 of the formation of the display sequence (type of arrangement (random succession colors and / or random display duration), periodicity of a random pattern, random luminous power), the colored fields of the video sequence SV received at the input are re-arranged in a step 100.2 of forming the sequence of SD display, according to these chosen implementation options, and imposed constraints: an SV display sequence is formed in a step 100.2, if necessary with the concurrence 100.3 of a pseudo-random generator to provide characteristic times colored fields: frequency of repetition of a random pattern, minimum and maximum values of durations, color balance. An SD display sequence is then output, which is applied to the LCD display 1, associated with a corresponding CBAL control mode of the light box 2: color succession, lighting duration, lighting power.
  • a parameterization 100.1 of the formation of the display sequence type of arrangement (random succession colors and / or random display duration), periodicity of a random pattern,
  • the invention which has just been described by means of a few nonlimiting examples makes it possible to improve the display quality of liquid crystal displays of the sequential color addressing type, and is applicable to the whole range of direct vision screens.

Abstract

The invention relates to a method for addressing an LCD display in a colour sequential mode, in which the coloured frames fRk, fGk, fβk of a received video sequence SV are rearranged in order to form a display sequence SV applied on the LCD display 1. The arrangement of the coloured frames in the SD display sequence is such that the colour succession of the coloured frames and/or the duration of the coloured frame is a random one. Application in direct vision screens.

Description

PROCEDE D'ADRESSAGE D1UN AFFICHEUR A CRISTAUX LIQUIDES EN MODE SEQUENTIEL COULEURMETHOD FOR ADDRESSING A 1 LIQUID CRYSTAL DISPLAY MODE SEQUENTIAL COLOR
La présente invention concerne un afficheur à cristaux liquides du type à adressage séquentiel couleur, et plus particulièrement un procédé d'adressage d'un tel afficheur. Elle s'applique plus particulièrement à toute la gamme des écrans à vision directe, allant des écrans de téléphone cellulaire aux écrans de grandes dimensions pour la télévision.The present invention relates to a liquid crystal display of the sequential color addressing type, and more particularly to a method of addressing such a display. It is particularly applicable to the full range of direct view displays, ranging from cell phone screens to large screens for television.
Un intérêt des afficheurs de type séquentiel couleur est la possibilité de réaliser des systèmes d'affichage couleur pour des écrans de vision directe sans filtres colorés, c'est à dire sans information de couleur attachée à un point image (pixel). Chaque point image est incolore et une boîte à lumière est utilisée qui permet successivement d'éclairer l'afficheur dans les trois couleurs primaires, typiquement, en rouge, en vert et en bleu.An interest of color sequential displays is the possibility of producing color display systems for direct vision screens without color filters, that is to say without color information attached to an image point (pixel). Each image point is colorless and a light box is used which successively illuminates the display in the three primary colors, typically red, green and blue.
L'adressage comprend alors plusieurs trames colorées par trame vidéo complète. Dans le temps de chaque trame colorée, tous les pixels de la matrice sont adressés pour afficher l'information vidéo correspondant à la couleur primaire associée, et la boîte à lumière éclaire l'afficheur dans la couleur primaire correspondante.The addressing then comprises several color frames per complete video frame. In the time of each color frame, all the pixels of the matrix are addressed to display the video information corresponding to the associated primary color, and the light box illuminates the display in the corresponding primary color.
Une séquence colorée correspondante est illustrée sur la figure 1 : Dans chaque trame, F1 par exemple, se succèdent trois trames colorées, rouge, vert et bleu, dans l'exemple fRi , fd et fβ1 respectivement. La séquence colorée rouge, vert, bleu se répète périodiquement, à la fréquence des trames vidéo complètes. Dans l'exemple, la fréquence trame est égale à 60Hz donnant une durée TO de 16, 667ms pour chaque trame vidéo.A corresponding color sequence is illustrated in FIG. 1: In each frame, F1, for example, there are three colored fields, red, green and blue, in the example fRi, fd and fβ1, respectively. The red, green, blue color sequence is repeated periodically at the frequency of the complete video frames. In the example, the frame rate is 60Hz giving a TO duration of 16.667ms for each video frame.
Un problème connu de ces afficheurs est le problème dit de rupture des couleurs "Color Break-up", dû au temps de stabilisation du cristal liquide, qui se traduit par un défaut d'affichage perceptible pour l'oeil d'un observateur. En effet, du fait de la capacité de l'œil à distinguer des mouvements très rapides, il est capable de distinguer la succession des différentes trames colorées. Notamment, un observateur perçoit des clignotements de couleurs particulièrement visibles sur une image blanche lorsque l'écran fonctionne à basse fréquence ou lorsqu'il bouge la tête en face de l'écran. Alors que l'œil accepte sans être trop gêné un rafraîchissement complet des images à 50Hz, une modification des couleurs à la fréquence de 150Hz peut être détectée dans les cas d'observation tels que ceux cités ci dessus.A known problem of these displays is the so-called color break-up problem, due to the stabilization time of the liquid crystal, which results in a noticeable display defect for the eye of an observer. Indeed, because of the ability of the eye to distinguish very fast movements, it is able to distinguish the succession of different colored frames. In particular, an observer perceives Particularly visible color flashes on a white image when the screen is operating at low frequency or when moving the head in front of the screen. While the eye accepts without being too embarrassed a complete refresh of the images at 50Hz, a color change at the frequency of 150Hz can be detected in cases of observation such as those mentioned above.
La perception par l'œil de ce défaut d'affichage prend la forme d'une succession de bandes ou franges colorées, typiquement la succession des couleurs primaires, comme illustré schématiquement sur la figure 1 , avec une fréquence spatiale qui dépend de la fréquence de rafraîchissement de l'image. Ainsi, dans l'exemple, l'œil perçoit une succession périodique d'une bande rouge, d'une bande verte, et d'une bande bleue.The perception by the eye of this display defect takes the form of a succession of bands or colored fringes, typically the succession of primary colors, as illustrated schematically in Figure 1, with a spatial frequency which depends on the frequency of refresh the image. Thus, in the example, the eye perceives a periodic succession of a red band, a green band, and a blue band.
On notera ici que l'on a par convention représenté le rouge en pointillé blanc sur fond noir, le vert en traits pointillés noirs obliques sur fond blanc et le bleu par un quadrillé de traits noirs sur fond blanc.We note here that we have conventionally represented the red dashed white on a black background, the green dashed black lines oblique on a white background and the blue by a checkered black lines on a white background.
Pour résoudre ce problème de défaut d'affichage dû à la succession périodique des trames colorées, on cherche habituellement à augmenter la fréquence des trames vidéo, en particulier à la doubler. L'effet de rupture des couleurs est atténué. Néanmoins il reste encore bien visible, car il n'est pas possible de rafraîchir l'image à trop haute fréquence, pour des raisons de compatibilité technologique avec les écrans à matrice active. Aussi la fréquence image reste très en dessous du seuil définissant la limite de perception du phénomène, selon l'acuité visuelle d'un observateur standard. Dans l'invention, on a cherché à résoudre ce problème d'une autre manière, en proposant des arrangements temporels et/ou spatiaux particuliers des trames colorées, pour élaborer des séquences colorées présentées à l'afficheur, qui soient telles que la succession des couleurs selon ces arrangements devient imperceptible, ou quasiment imperceptible à l'œil. Ces arrangements peuvent avantageusement se combiner à des arrangements des puissances lumineuses émises dans les phases d'éclairage successives de l'afficheur. L'invention concerne un procédé d'adressage d'un afficheur à cristaux liquides en séquentiel couleur, à partir d'une séquence vidéo de trames colorées successives, qui comprend une étape d'arrangement aléatoire ou pseudo-aléatoire desdites trames colorées de ladite séquence vidéo, pour fournir une séquence d'affichage de trames colorées à appliquer sur ledit afficheur, ledit arrangement aléatoire comprenant un arrangement aléatoire ou pseudo-aléatoire de l'ordre d'affichage desdites trames colorées, et/ou une attribution aléatoire ou pseudo-aléatoire de durée de chacune desdites trames colorées. Selon l'invention, ledit arrangement aléatoire est tel que ladite séquence d'affichage comprend une succession de paquets de n trames colorées, n entier au moins égal à 3, chaque paquet étant associé à une paire de couleurs primaires, comprenant une première couleur primaire et une deuxième couleur primaire, les trames colorées de rang impair dans un paquet étant des trames colorées correspondant à ladite première couleur, les trames colorées de rang pair dans le paquet étant des trames colorées correspondant à ladite deuxième couleur.To solve this problem of display failure due to the periodic succession of color frames, it is usually sought to increase the frequency of the video frames, in particular to double it. The color break effect is attenuated. Nevertheless, it is still very visible, because it is not possible to refresh the image at too high frequency, for reasons of technological compatibility with active matrix screens. Also the image frequency remains well below the threshold defining the perception limit of the phenomenon, according to the visual acuity of a standard observer. In the invention, an attempt has been made to solve this problem in another way, by proposing particular temporal and / or spatial arrangements of the colored fields, in order to produce colored sequences presented on the display, which are such that the succession of colors according to these arrangements becomes imperceptible, or almost imperceptible to the eye. These arrangements can advantageously be combined with arrangements of the light powers emitted in the successive lighting phases of the display. The invention relates to a method for addressing a color sequential liquid crystal display, from a video sequence of successive color frames, which comprises a step of random or pseudo-random arrangement of said colored fields of said sequence. video, for providing a sequence of display of color frames to be applied to said display, said random arrangement comprising a random or pseudo-random arrangement of the display order of said color frames, and / or a random or pseudo-random assignment duration of each of said colored fields. According to the invention, said random arrangement is such that said display sequence comprises a succession of packets of n colored frames, n being at least equal to 3, each packet being associated with a pair of primary colors, comprising a first primary color and a second primary color, the odd-rank colored fields in a packet being color fields corresponding to said first color, the even-rank colored fields in the packet being colored fields corresponding to said second color.
Le niveau de puissance de lumière émis dans la phase d'éclairage d'une trame colorée est avantageusement aléatoire. Dans une variante, le niveau de puissance de lumière de chaque trame colorée est tel que la puissance lumineuse reconstituée sur l'afficheur, correspond à un blanc achromatique.The power level of light emitted in the lighting phase of a colored frame is advantageously random. In a variant, the light power level of each colored frame is such that the light power reconstituted on the display corresponds to an achromatic white.
L'invention concerne aussi un afficheur à cristaux liquides du type à adressage séquentiel des couleurs, comprenant un dispositif d'adressage mettant en œuvre un procédé d'adressage selon l'invention.The invention also relates to a liquid crystal display of the sequential color addressing type, comprising an addressing device implementing an addressing method according to the invention.
D'autres avantages et caractéristiques de l'invention sont détaillés dans la description suivante en référence aux dessins illustrés donnés à titre d'exemple non limitatif. Dans ces dessins : -la figure 1 déjà décrite illustre une séquence colorée suivant l'état de l'art; -la figure 2 déjà décrite illustre le phénomène de coupure des couleurs tel que perçu par l'œil d'un observateur; -la figure 3 illustre une séquence de trames colorées constituées par un procédé d'adressage selon l'invention;Other advantages and features of the invention are detailed in the following description with reference to the illustrated drawings given by way of non-limiting example. In these drawings: FIG. 1 already described illustrates a colored sequence according to the state of the art; FIG. 2 already described illustrates the phenomenon of cleavage of colors as perceived by the eye of an observer; FIG. 3 illustrates a sequence of colored frames constituted by a addressing method according to the invention;
-la figure 4 illustre un afficheur avec un dispositif d'adressage pour la mise en œuvre d'un procédé selon l'invention;FIG. 4 illustrates a display with an addressing device for implementing a method according to the invention;
-la figure 5 illustre une séquence de trames colorées selon un premier mode de réalisation de l'invention;FIG. 5 illustrates a sequence of colored fields according to a first embodiment of the invention;
-la figure 6 illustre une séquence de trames colorées suivant une variante du premier mode de réalisation;FIG. 6 illustrates a sequence of colored fields according to a variant of the first embodiment;
-la figure 7 illustre une séquence de trames colorées selon un deuxième mode de réalisation de l'invention; -la figure 8 est un synoptique général d'un procédé d'adressage d'un afficheur LCD selon l'invention.FIG. 7 illustrates a sequence of colored fields according to a second embodiment of the invention; FIG 8 is a general block diagram of a method of addressing an LCD display according to the invention.
A titre liminaire, on rappelle que dans les afficheurs LCD, on utilise le système additif de trois faisceaux de couleurs primaires qui sont le rouge vif (ou rouge) noté R, le vert vif (ou vert) noté G, et le bleu foncé (ou bleu) noté B, pour reconstituer une lumière blanche. Ces couleurs primaires sont représentées sur les figures, le rouge R en pointillé blanc sur fond noir, le vert G en traits pointillés noirs obliques sur fond blanc et le bleu B par un quadrillé de traits noirs sur fond blanc.As a preliminary, we recall that in LCD displays, we use the additive system of three primary color beams that are bright red (or red) R, bright green (or green) G, and dark blue ( or blue) noted B, to reconstitute a white light. These primary colors are represented in the figures, the red R in white dotted lines on a black background, the green G in oblique black dotted lines on a white background and the B blue in a checkered pattern of black lines on a white background.
L'addition de deux couleurs primaires donne une couleur secondaire, comme suit :The addition of two primary colors gives a secondary color, as follows:
Couleurs primaires ^ Couleur secondaire obtenuePrimary colors ^ Secondary color obtained
Bleu B + Vert G *. Bleu cyan, noté BcBlue B + Green G *. Cyan blue, noted Bc
Bleu B + Rouge R »- Pourpre ou Rouge Magenta, noté MBlue B + Red R "- Purple or Magenta Red, noted M
Bleu B + Vert G * Jaune, noté Y, et dans les figures, le bleu cyan Bc est représenté en gris foncé, le pourpre M en gris clair et le jaune Y en gris moyen.Blue B + Green G * Yellow, noted Y, and in the figures, cyan blue Bc is represented in dark gray, purple M in light gray and yellow Y in medium gray.
Les figures 3 et 4 illustrent un procédé d'adressage selon l'invention, dans lequel les trames colorées d'une séquence vidéo SV sont arrangées aléatoirement ou quasi aléatoirement, pour constituer une séquence d'affichage SD de trames colorées appliquée à un afficheur 1. Cet arrangement aléatoire ou pseudo-aléatoire selon l'invention s'applique à l'ordre d'affichage des trames colorées sur l'afficheur 1 , et/ou à la durée de chacune des trames colorées.FIGS. 3 and 4 illustrate an addressing method according to the invention, in which the colored frames of a video sequence SV are arranged randomly or almost randomly to constitute a display sequence SD of colored frames applied to a display 1 This random or pseudo-random arrangement according to the invention applies to the order of display of the colored fields on the display 1, and / or to the duration of each of the colored fields.
En exemple, la séquence d'affichage SD constituée selon l'invention comprend une suite de trames colorées fRi , fd , fBi , fG2, fB2, fR2, fG3, fR3, fB3, correspondant à une succession aléatoire des couleurs primaires suivant la séquence R G B G B R G R B, chaque trame colorée correspondante ayant une durée propre, choisie aléatoirement, dans l'exemple tii , tg1 , tb1 , tg2, tb2, tr2, tg3, tr3, tb3... , respectivement.As an example, the display sequence SD constituted according to the invention comprises a series of colored frames fRi, fd, fBi, fG2, fB2, fR2, fG3, fR3, fB3, corresponding to a random succession of the primary colors according to the sequence RGBGBRGRB , each corresponding colored frame having a specific duration, chosen randomly, in the example tii, tg1, tb1, tg2, tb2, tr2, tg3, tr3, tb3 ..., respectively.
De manière connue dans l'état de l'art, une trame complète d'une image vidéo couleur à afficher comprend trois trames vidéo couleur successives, toujours dans le même ordre, typiquement une trame vidéo rouge, puis verte, puis bleue. Un dispositif d'adressage traite les trames vidéo complètes avec leurs trames vidéo couleur présentées dans l'ordre à l'afficheur. Pour chaque trame vidéo couleur, le dispositif d'adressage lit les données correspondantes à afficher pour commander les pixels de la matrice dans une phase d'écriture appropriée, et la matrice est éclairée dans la couleur primaire correspondante.In a manner known in the state of the art, a complete frame of a color video image to be displayed comprises three successive color video frames, always in the same order, typically a red video frame, then green then blue. An addressing device processes the complete video frames with their color video frames presented in order on the display. For each color video frame, the addressing device reads the corresponding data to be displayed to control the pixels of the array in an appropriate write phase, and the array is illuminated in the corresponding primary color.
Dans l'invention, le dispositif d'affichage arrange les trames vidéo couleur d'une ou de plusieurs trames vidéo complètes, pour constituer une séquence SD de trames colorées dans lesquelles les couleurs primaires se présentent en séquence de manière aléatoire, et/ou dans lesquelles les durées des trames colorées sont aléatoires.In the invention, the display device arranges the color video frames of one or more complete video frames to form an SD sequence of color frames in which the primary colors occur in random sequence, and / or which the durations of the colored frames are random.
On note Fk (k entier) les trames vidéo complètes transmises par un signal d'entrée d'une séquence vidéo SV, contenant les images à afficher. On note fRk, fGk, fBk, les trames vidéo couleur rouge, verte, bleue d'une trame vidéo Fk de la séquence vidéo SV.We denote by Fk (k integer) the complete video frames transmitted by an input signal of a video sequence SV, containing the images to be displayed. FRk, fGk, fBk are the red, green, blue video frames of a video frame Fk of the video sequence SV.
Ainsi, comme illustré sur la figure 4 en correspondance avec l'exemple de la séquence d'affichage SD illustrée sur la figure 3, un dispositif d'affichage selon l'invention constitue une séquence d'affichage SD appliquée sur l'afficheur 1 , à partir des trames colorées de la séquence vidéo reçue. Cette constitution d'une séquence d'affichage SD selon l'invention consiste à présenter les trames vidéo couleur dans un ordre aléatoire et/ou à leur attribuer un temps trame, ou durée, aléatoire. Dans l'exemple illustré en relation avec les figures 3 et 4, on a la combinaison des deux processus aléatoires : ordre des trames colorées et temps trame attribué à chaque trame colorée. En référence à cet exemple et à ces figures, la séquence d'affichage SD selon l'invention peut être réalisée comme décrit ci-après.Thus, as illustrated in FIG. 4 in correspondence with the example of the display sequence SD illustrated in FIG. 3, a display device according to the invention constitutes a display sequence SD applied to the display 1, from the colored fields of the received video sequence. This constitution of an SD display sequence according to the invention consists in presenting the color video frames in a random order and / or in assigning them a frame time, or duration, random. In the example illustrated with reference to FIGS. 3 and 4, there is the combination of the two random processes: order of the colored fields and frame time allocated to each color frame. With reference to this example and to these figures, the display sequence SD according to the invention can be performed as described below.
Un signal vidéo à afficher est reçu sous forme d'une séquence vidéo SV de trames vidéo. Le dispositif d'affichage 10 comprend des moyensA video signal to be displayed is received in the form of an SV video sequence of video frames. The display device 10 comprises means
11 pour constituer à partir des trames colorées de cette séquence vidéo SV, une séquence d'affichage SD de trames colorées, par exemple la séquence SD décrite à la figure 3.11 to form from the colored frames of this video sequence SV, an SD display sequence of colored fields, for example the SD sequence described in FIG.
Dans un mode de réalisation de l'invention k trames vidéo successives F1 à Fk (k nombre entier non nul) de la séquence sont mémorisées par exemple dans une mémoire tampon 12 alimentée par le signal entrant SV, pour permettre la constitution d'une séquence d'affichage selon l'invention. Dans l'exemple illustré en figure 4, la mémoire tampon est alimentée par 4 trames vidéo successives, F1 à F4 qui comprennent respectivement les trames colorées suivantes : fRi , fGi , fβ1 pour F1 , fR2, fG2, fB2 pour F2, fR3, fG3, fB3 pour F3, fR4, fG4, fB4 pour F4.In one embodiment of the invention k successive video frames F1 to Fk (k nonzero integer) of the sequence are stored for example in a buffer 12 fed by the incoming signal SV, to allow the constitution of a sequence display according to the invention. In the example illustrated in FIG. 4, the buffer memory is fed by 4 successive video frames, F1 to F4, which respectively comprise the following color frames: fRi, fGi, fβ1 for F1, fR2, fG2, fB2 for F2, fR3, fG3 , fB3 for F3, fR4, fG4, fB4 for F4.
La séquence d'affichage SD peut se constituer au fur et à mesure du remplissage de la mémoire tampon d'entrée 12 par les trames de la séquence vidéo SV, et elle peut elle-même être mémorisée au fur et à mesure dans une mémoire tampon 13 comme illustré, ou alimenter directement un dispositif de commande 14 de l'afficheur LCD 1. Les trames colorées de la séquence d'affichage SD sont ainsi successivement affichées sur l'afficheur LCD 1.The display sequence SD can be constituted as filling of the input buffer 12 by the frames of the video sequence SV, and it can itself be stored as a buffer buffer 13 as illustrated, or supply directly to a control device 14 of the LCD display 1. The colored fields of the display sequence SD are thus successively displayed on the LCD display 1.
En parallèle, la boîte à lumière 2 est pilotée de façon synchrone pour éclairer l'afficheur LCD en correspondance avec l'affichage de la trame colorée courante de la séquence SD, pendant le temps trame alloué à cette trame colorée, qui peut être fixe ou aléatoire selon l'implémentation de l'invention.In parallel, the light box 2 is controlled synchronously to illuminate the LCD display in correspondence with the display of the current colored frame of the SD sequence, during the frame time allocated to this colored frame, which can be fixed or random according to the implementation of the invention.
En ce qui concerne la constitution de la séquence d'affichage des trames colorées, on notera que dans l'exemple illustré sur les figures 3 et 4, l'ordre des trames colorées est aléatoire sur la durée d'une trame complète vidéo Fk. En d'autres termes, chaque paquet de trois trames colorées de la séquence d'affichage SD correspond aux trames colorées d'une trame vidéo Fk de la séquence vidéo SV, mais présentées dans un ordre aléatoire par rapport à leur ordre naturel dans la séquence vidéo SV d'origine, et/ou étant chacune associée à un temps trame aléatoire. Dans cet exemple de mise en œuvre de l'invention, les moyens 1 1 de constitution de la séquence d'affichage SD prennent la première trame vidéo complète F1 de la séquence vidéo SV mémorisée dans la mémoire tampon, et constituent un premier paquet p1 de la séquence SD en tirant un ordre aléatoire d'affichage des trois trames colorées fRi , fGi , fβ1 de cette trame vidéo F1 ; puis les moyens 1 1 passent à la trame complète vidéo suivante F2, pour constituer un deuxième paquet p2 avec ses trames colorées fR2, fG2, fβ2 ... et ainsi de suite. La séquence d'affichage SD est ainsi constituée de la suite des paquets p1 , p2,...With regard to the constitution of the display sequence of the colored fields, it will be noted that in the example illustrated in FIGS. 3 and 4, the order of the colored frames is random over the duration of a full video frame Fk. In other words, each packet of three colored fields of the display sequence SD corresponds to the colored fields of a video frame Fk of the video sequence SV, but presented in a random order with respect to their natural order in the sequence original SV video, and / or being each associated with a random frame time. In this exemplary implementation of the invention, the means 1 1 constituting the display sequence SD take the first complete video frame F1 of the video sequence SV stored in the buffer memory, and constitute a first packet p1 of the SD sequence by drawing a random order of display of the three color frames fRi, fGi, fβ1 of this video frame F1; then the means 1 1 pass to the next complete video frame F2, to form a second packet p2 with its colored frames fR2, fG2, fβ2 ... and so on. The display sequence SD thus consists of the sequence of packets p1, p2, ...
L'invention ne se limite pas à ce mode de réalisation d'une séquence d'affichage SD. Plus généralement, la séquence d'affichage SD peut être constituée à partir des trames colorées d'une ou de plusieurs trames vidéo Fk. De tels modes de réalisation d'une séquence d'affichage SD à partir des trames colorées de plusieurs trames F1 à Fk d'une séquence vidéo d'entrée SV sont notamment illustrés sur les figures 5 et 6. Dans ce cas, la mémoire tampon d'entrée 12 contiendra au moins les k trames à partir desquelles sera constituée une suite de paquets de la séquence d'affichage. En pratique, la mise en oeuvre de l'invention doit satisfaire à différentes contraintes, pour produire pleinement tous ses effets et ne pas dégrader les performances de l'afficheur. Notamment, trois contraintes doivent être prises en compte :The invention is not limited to this embodiment of an SD display sequence. More generally, the display sequence SD can be constituted from the colored fields of one or more video frames Fk. Such embodiments of a display sequence SD from the color frames of several frames F1 to Fk of an input video sequence SV are illustrated in particular in FIGS. 5 and 6. In this case, the buffer memory input 12 will contain at least k frames from which will be constituted a sequence of packets of the display sequence. In practice, the implementation of the invention must meet different constraints, to fully produce all its effects and not degrade the performance of the display. In particular, three constraints must be taken into account:
-la durée d'une trame colorée de la séquence d'affichage SD doit être suffisamment petite pour ne pas marquer l'œil d'un observateur de façon durable.the duration of a colored frame of the display sequence SD must be sufficiently small so as not to mark the eye of an observer in a lasting manner.
-la durée d'une trame colorée de la séquence d'affichage SD ne doit pas être trop courte de façon à être compatible avec les performances du cristal liquide sur la matrice active. Notamment il doit être supérieur au temps de stabilisation du cristal liquide dont une valeur typique est de l'ordre de la milliseconde. -la balance des couleurs doit être préservée, pour obtenir un blanc achromatique. Typiquement, ceci est obtenu avec une puissance lumineuse reconstituée sur l'afficheur comprenant 60% de vert, 20% de rouge et 20% de bleu.the duration of a colored frame of the display sequence SD must not be too short to be compatible with the performance of the liquid crystal on the active matrix. In particular, it must be greater than the stabilization time of the liquid crystal, a typical value of which is of the order of a millisecond. the color balance must be preserved to obtain an achromatic white. Typically, this is achieved with a light power reconstituted on the display including 60% green, 20% red and 20% blue.
Les deux premières contraintes imposent un intervalle de valeurs possibles pour les temps trames colorées, avec une valeur minimum Tmιn (deuxième contrainte) et une valeur maximum Tmax (première contrainte). La dernière contrainte implique de ne pas privilégier pendant un temps trop long (perceptible à l'œil) une couleur primaire par rapport à une autre.The first two constraints impose an interval of possible values for the colored field times, with a minimum value T mιn (second constraint) and a maximum value T max (first constraint). The last constraint implies not to favor for a long time (perceptible to the eye) one primary color compared to another.
Dans la mesure où l'on attribue des temps trames aléatoires et/ou des séquences dans lesquelles les couleurs se présentent dans un ordre aléatoire, il faut ainsi de préférence choisir des implémentations de l'invention comprenant des règles ou contraintes pour constituer la séquence d'affichage SD. En d'autres termes, on préfère en pratique mettre en œuvre un arrangement pseudo-aléatoire, qui permet à la fois de supprimer l'effet de rupture des couleurs ou d'en atténuer la perception de façon très importante, et de conserver par ailleurs des performances optimales pour l'afficheur.Since random frame times and / or sequences in which the colors occur in a random order are assigned, it is thus preferable to choose implementations of the invention comprising rules or constraints for constituting the sequence of FIG. SD display. In other words, it is preferred in practice to implement a pseudo-random arrangement, which makes it possible both to suppress the effect of color failure or to attenuate the perception of it in a very important manner, and to preserve otherwise optimal performance for the display.
L'implémentation de l'invention suppose ainsi la mise en œuvre de règles aléatoires contraintes de sélection des couleurs et/ou des temps trames, qui vont donner le mécanisme d'arrangement des trames colorées de la séquence vidéo reçue SV pour former la séquence d'affichage SD selon l'invention. A ce mécanisme, on peut ajouter de façon avantageuse un mode de commande de la boîte à lumière qui éclaire l'afficheur LCD dans chacune des couleurs en relation avec la trame colorée courante affichée, selon lequel la puissance lumineuse émise par cette boîte à lumière dans chaque phase d'éclairage, c'est à dire pour chaque trame colorée courante, est aléatoire. Dans une variante, le mode de commande du niveau de puissance lumineuse de la boîte à lumière est tel que la puissance lumineuse reconstituée sur l'afficheur correspond à un blanc achromatrique.The implementation of the invention thus presupposes the implementation of random rules with color selection constraints and / or frame times, which will give the mechanism for arranging the colored frames of the video sequence received SV to form the sequence of SD display according to the invention. To this mechanism, it is advantageous to add a control mode of the light box which illuminates the LCD display in each of the colors in relation to the current colored frame displayed, according to which the light power emitted by this light box in each lighting phase, ie for each current color frame, is random. In a variant, the control mode of the level of The luminous power of the light box is such that the luminous power reconstituted on the display corresponds to an achromatric white.
Les figures 5 à 7 illustrent des exemples d'implémentations d'arrangements pseudo-aléatoires conformes à l'invention, dans lesquels une succession pseudo-aléatoire des couleurs est obtenue. Ces exemples ne sont pas limitatifs.Figures 5 to 7 illustrate examples of implementations of pseudo-random arrangements according to the invention, in which a pseudo-random succession of colors is obtained. These examples are not limiting.
Dans ces figures, les séquences d'affichage SD données en exemples sont constituées à partir de la séquence vidéo d'entrée SV illustrée sur les figures 1 et 4. Dans les implémentations des figures 5 et 6, la séquence d'affichage SD de trames colorées selon l'invention est constituée d'une façon telle que les ruptures de couleurs se produisent avantageusement dans les couleurs secondaires jaune Y (vert + jaune), rouge magenta M (bleu + rouge), ou bleu cyan Bc (bleu + vert). Ces ruptures dans les couleurs secondaires sont moins perceptibles pour l'œil d'un observateur que les ruptures de couleurs primaires.In these figures, the SD display sequences given in examples are formed from the SV input video sequence illustrated in FIGS. 1 and 4. In the implementations of FIGS. 5 and 6, the display sequence SD of frames stained according to the invention is constituted in such a way that the color breaks advantageously occur in the secondary colors yellow Y (green + yellow), red magenta M (blue + red), or blue cyan Bc (blue + green) . These breaks in the secondary colors are less noticeable for the eye of an observer than the primary color breaks.
La figure 5 illustre un premier mode de réalisation correspondant. La séquence d'affichage SD est constituée d'une suite de paquets de n=3 trames colorées, chaque paquet étant associé à une paire de couleurs primaires comprenant une première couleur primaire et une deuxième couleur primaire. Dans le paquet considéré, les trames colorées de rang impair, typiquement celles des rangs 1 et 3 (n=3) sont des trames colorées correspondant à la première couleur primaire et les trames colorées de rang pair, typiquement celle de rangs 2 (n=3), sont des trames colorées correspondant à la deuxième couleur primaire.Figure 5 illustrates a corresponding first embodiment. The display sequence SD consists of a series of packets of n = 3 colored fields, each packet being associated with a pair of primary colors comprising a first primary color and a second primary color. In the considered packet, the odd-rank colored frames, typically those of the ranks 1 and 3 (n = 3), are colored fields corresponding to the first primary color and even-rank colored frames, typically those of ranks 2 (n = 3), are colored fields corresponding to the second primary color.
La figure 6 illustre une variante de ce mode de réalisation dans lequel les paquets comprennent n=4 trames colorées : dans un paquet, les trames de rang impair 1 et 3 sont associées à la première couleur primaire et les trames colorées de rang pair 2 et 4 sont associées à la deuxième couleur primaire.FIG. 6 illustrates a variant of this embodiment in which the packets comprise n = 4 color frames: in a packet, the odd-rank 1 and 3 frames are associated with the first primary color and the even-rank 2 color frames and 4 are associated with the second primary color.
Dans ce mode de réalisation (figures 5 et 6), deux paquets successifs sont associés à une paire différente de couleurs primaires. Avantageusement, la couleur de la trame colorée de rang n d'un paquet de la séquence d'affichage SD et la couleur de la trame colorée de rang 1 du paquet suivant de ladite séquence sont différentes.In this embodiment (FIGS. 5 and 6), two successive packets are associated with a different pair of primary colors. Advantageously, the color of the n-rank colored frame of a packet of the display sequence SD and the color of the rank 1 colored frame of the next packet of said sequence are different.
En pratique, et comme illustré sur la figure 5, une séquence d'affichage SD correspondante peut comprendre une succession de sous- séquences SDi, SD2 de même longueur, suivant le même motif aléatoire, chaque sous-séquence étant élaborée à partir de k=3 trames vidéo F1 à Fk successives de la séquence vidéo d'entrée SV, dans l'exemple à partir des trois trames vidéo successives F1 à F3 des figures 1 et 4. Dans cet exemple, chaque sous-séquence comprend trois paquets de n=3 trames. Pour former le premier paquet p1 , une succession de 3 trames colorées est sélectionnée sur la base d'une paire d'une première et d'une deuxième couleurs primaires choisie parmi six paires possibles (R1G), (G, R), (G1B), (B1G), (R1B) ou (B, R). Dans l'exemple, la paire (R, G) est associée au paquet p1 , la première couleur R de la paire donnant la couleur de la première et de la troisième des trois trames colorées du paquet p1 , et la deuxième couleur G donnant la couleur de la deuxième trame colorée du paquet. Les moyens 11 (figure 4) vont alors sélectionner des trames colorées correspondantes dans la séquence vidéo SV, suivant leur ordre d'apparition chronologique et selon les couleurs recherchées, ce qui donne dans l'exemple pour le paquet p1 pour la première trame colorée, fRi , pour la deuxième trame colorée, fd , et pour la troisième trame colorée, fR2. Les paquets suivants p2, p3 de la sous- séquence sont constitués suivant le même principe : dans l'exemple, le deuxième paquet p2 correspond à la sélection de la paire de couleurs primaires (B, R) et est constitué avec les trames fBi , fR3 et fB2 de la séquence SV, associées à cette sélection de couleurs. Le troisième paquet p3 correspond à la sélection de la paire de couleurs primaires (G, B) et est constituée avec les trames fG2, fB3 et fG3 de la séquence SV, associées à cette sélection de couleurs. La succession des couleurs imposée par la sélection des pairesIn practice, and as illustrated in FIG. 5, a corresponding SD display sequence may comprise a succession of sub-sequences SDi, SD 2 of the same length, according to the same random pattern, each subsequence being elaborated from k = 3 successive video frames F1 to Fk of the input video sequence SV, in the example from the three successive video frames F1 to F3 of FIGS. 1 and 4. In this example, each subsequence comprises three packets of n = 3 frames. To form the first packet p1, a succession of 3 color frames is selected on the basis of a pair of first and second primary colors selected from six possible pairs (R 1 G), (G, R), (G 1 B), (B 1 G), (R 1 B) or (B, R). In the example, the pair (R, G) is associated with the packet p1, the first color R of the pair giving the color of the first and the third of the three colored fields of the packet p1, and the second color G giving the color of the second colored frame of the packet. The means 11 (FIG. 4) will then select corresponding color frames in the video sequence SV, according to their order of chronological appearance and according to the desired colors, which gives in the example for the packet p1 for the first colored frame, fRi, for the second colored field, fd, and for the third colored field, fR2. The following packets p2, p3 of the subsequence are constituted according to the same principle: in the example, the second packet p2 corresponds to the selection of the pair of primary colors (B, R) and is constituted with fBi frames, fR3 and fB2 of the SV sequence, associated with this color selection. The third packet p3 corresponds to the selection of the primary color pair (G, B) and is constituted with the frames fG2, fB3 and fG3 of the sequence SV, associated with this selection of colors. The succession of colors imposed by the selection of pairs
(R1G) pour p1 , (B1R) pour p2 et (G1B) pour p3 donne le motif aléatoire de la sous-séquence SDi : RGRBRBGBG. Ce motif est répété pour chaque sous- séquence SDj comme illustré sur la figure 5 pour la séquence SD2.(R 1 G) for p1, (B 1 R) for p2 and (G 1 B) for p3 gives the random pattern of the subsequence SDi: RGRBRBGBG. This pattern is repeated for each sub- SD sequence j as illustrated in Figure 5 for the sequence SD2.
Si on prend l'exemple de la figure 6, dans laquelle les paquets de la séquence colorée comprennent chacun n=4 trames colorées, le motif aléatoire constitué dans l'exemple est le suivant : RGRGBRBRBGBG. Une séquence d'affichage SD correspondante peut être formée à partir des 12 trames colorées de k=4 trames vidéo F1 à Fk successives, dans l'exemple (Figure 4), à partir des trames colorées de F1 à F4.Taking the example of FIG. 6, in which the packets of the colored sequence each comprise n = 4 colored frames, the random pattern constituted in the example is the following: RGRGBRBRBGBG. A corresponding SD display sequence may be formed from the 12 colored fields of k = 4 successive video frames F1 to Fk, in the example (FIG. 4), from the colored fields of F1 to F4.
Le mode de réalisation de l'invention qui vient d'être décrit en relation avec les figures 5 et 6 a l'avantage de permettre une implémentation pratique simple, nécessitant des moyens mémoire limités.The embodiment of the invention which has just been described in relation to FIGS. 5 and 6 has the advantage of allowing a simple practical implementation, requiring limited memory means.
La figure 7 illustre un autre mode de réalisation d'une séquence d'affichage SD selon l'invention à partir de la séquence vidéo d'entrée SV. Dans ce mode de réalisation, on utilise avantageusement la périodicité spatiale du phénomène de rupture des couleurs primaires pour le supprimer, Un ordre de grandeur de la périodicité spatiale à utiliser est le 10ιeme, 100ιeme, de millimètres ou de centimètres.Fig. 7 illustrates another embodiment of a display sequence SD according to the invention from the input video sequence SV. In this embodiment, use is advantageously the spatial periodicity of the phenomenon of rupture of the primary colors to remove, an order of magnitude of the spatial frequency to be used is 10 ιeme 100 ιeme, millimeters or centimeters.
Selon ce principe, et comme illustré, dans une succession de 3 paquets p1 , p2, p3 de 3 trames colorées de la séquence d'affichage SD constituée, les trames colorées sont arrangées de telle façon que pendant le temps de la trame colorée en première position dans chaque paquet p1 , p2 et p3, on retrouve du rouge pour une trame, du vert pour une autre et du bleu pour une autre, soit globalement un blanc W. Ceci est reproduit pour chaque position de trame colorée des paquets, c'est à dire les deuxièmes positions et les troisièmes positions. On efface ainsi l'effet de périodicité spatiale des couleurs. Dans l'exemple illustré, on a ainsi en 1ères positions successivement le rouge, le vert et le bleu, en 2ιemes positions, le vert, le bleu et le rouge et en 3ιemes positions, le bleu, le rouge et le vert.According to this principle, and as illustrated, in a succession of 3 packets p1, p2, p3 of 3 colored fields of the SD display sequence constituted, the colored fields are arranged in such a way that during the time of the colored frame in first position in each packet p1, p2 and p3, there is red for one frame, green for another and blue for another, or globally a white W. This is reproduced for each color frame position of the packets, c ' ie the second positions and the third positions. This removes the effect of spatial periodicity of the colors. In the illustrated example, there are thus in positions 1 st successively red, green and blue, in two positions ιemes, green, blue and red and in positions 3 ιemes, blue, red and green .
Pour des raisons de simplicité de mise en œuvre déjà indiquées, la séquence d'affichage SD peut avantageusement être formée par répétition d'un motif aléatoire, qui est ici donné par la succession des couleurs sur la séquence des trois paquets successifs p1 à p3, soit : RGBGBRBRG. Ce motif aléatoire est alors répété d'une sous-séquence à l'autre ; SD-t, SD2,... Chaque sous-séquence d'affichage peut avantageusement être constituée à partir des trames colorées de 3 trames vidéo complètes successives de la séquence vidéo SV, telles que F1 , F2, F3.For the sake of simplicity of implementation already indicated, the display sequence SD may advantageously be formed by repetition of a random pattern, which is here given by the succession of colors on the sequence of the three successive packets p1 to p3, either: RGBGBRBRG. This random pattern is then repeated from one subsequence to another; SD- t, SD 2 , ... Each display sub-sequence can advantageously be constituted from the colored fields of 3 successive complete video frames of the video sequence SV, such as F1, F2, F3.
Lorsque la séquence SD est ainsi formée par répétition périodique d'un motif aléatoire, par exemple toutes les 9 trames colorées (figures 5 et 7) ou toutes les 12 trames colorées (figure 6), une contrainte sur la fréquence de répétition du motif aléatoire doit être appliquée, afin d'éviter des effets de scintillement ou "flicker" : la fréquence de répétition du motif aléatoire doit être supérieure à la fréquence pour laquelle ce scintillement apparaît, fréquence que l'on note ffϋcker-When the SD sequence is thus formed by periodic repetition of a random pattern, for example all 9 colored fields (FIGS. 5 and 7) or all 12 colored fields (FIG. 6), a constraint on the frequency of repetition of the random pattern must be applied, in order to avoid flicker or flicker effects: the frequency of repetition of the random pattern must be higher than the frequency for which this flicker appears, a frequency which is noted ffϋ c ker-
Selon un autre aspect de l'invention un arrangement de la séquence d'affichage SD à partir de la séquence vidéo SV selon l'invention comprend une attribution d'une durée aléatoire (temps trame) à chacune des trames colorées de la séquence. Dans ce cas, on prévoit de prendre en compte les contraintes suivantes:According to another aspect of the invention, an arrangement of the display sequence SD from the video sequence SV according to the invention comprises an allocation of a random duration (frame time) to each of the colored fields of the sequence. In this case, it is planned to take into account the following constraints:
-la durée minimum Tmjn pour l'affichage d'une trame colorée, permettant la stabilisation du cristal liquide et la charge des pixels de la matrice active de l'afficheur;the minimum duration T m j n for displaying a colored frame, allowing the stabilization of the liquid crystal and the charge of the pixels of the active matrix of the display;
-la durée maximum Tmax pour l'affichage d'une trame colorée, au-delà de laquelle la trame colorée sera perçue par l'observateur, ce qui doit être évité.the maximum duration T max for displaying a colored frame, beyond which the colored frame will be perceived by the observer, which must be avoided.
On note tin, i= 1 à 3 et n= r,g,b, les temps caractéristiques associés aux trames colorées (figures 3 et 4) : soit ti r, t2r, t3r les temps caractéristiques (temps trame) alloués aux trames colorées rouges fRi , fR2 et fR3 ; t1 g, t2g, t3g ceux alloués aux trames colorées vertes fGi , fG2 et fG3 ; et t1 b t2b t3b ceux alloués aux trames colorées bleues fBi , fB2, fB3.We denote tin, i = 1 to 3 and n = r, g, b, the characteristic times associated with the colored fields (figures 3 and 4): let ti r, t2r, t3r the characteristic times (frame time) allocated to the colored fields red fRi, fR2 and fR3; t1 g, t2g, t3g those allocated to the green colored fields fGi, fG2 and fG3; and t1 b t2b t3b those allocated to the blue colored fields fBi, fB2, fB3.
On prend l'exemple d'une séquence d'affichage constituée par répétition d'un motif aléatoire, par exemple un motif aléatoire sur 9 trames colorées.An example of a display sequence consisting of repeating a random pattern, for example a random pattern on 9 colored fields, is taken.
Si pour tout tin attribué à une trame colorée, i= 1 à 3, n=r,v,b, on vérifie Tmjn< tin <TmaXi on est sûr de disposer d'un temps optimum pour l'affichage de la trame.If for any tin assigned to a colored field, i = 1 to 3, n = r, v, b, we check T m j n <tin <T m a Xi we are sure to have an optimum time for the display of the frame.
Si on choisit les temps caractéristiques tin tels que leurs sommes dans chaque couleur sur la durée du motif aléatoire sont égales, soit dans l'exemple, si t1 r+ t2r+ t3r = t1 b+ t2b+ t3b = t1g+ t2g+ t3g, alors on aura une bonne balance des couleurs, avec des systèmes d'éclairement des trois couleurs primaires équilibrés : pour un temps d'allumage identique dans chaque couleur, on obtiendra un blanc achromatique pour chaque sous- séquence répétant le motif aléatoire.If we choose the characteristic times tin such as their sums in each color on the duration of the random pattern are equal, either in the example, if t1 r + t2r + t3r = t1b + t2b + t3b = t1g + t2g + t3g, then we will have a good color balance, with systems of illumination of the three balanced primary colors: for an identical ignition time in each color, an achromatic white will be obtained for each subsequence repeating the random pattern.
Enfin pour qu'un observateur ne perçoive pas d'effet de scintillement des trames colorées sur l'afficheur (flicker), les temps caractéristiques tin sur la durée du motif aléatoire selon de préférenceFinally, so that an observer does not perceive a flicker effect of the colored fields on the display (flicker), the characteristic times end on the duration of the random pattern according to preference
3 choisis tels que l'on vérifie 2-J Z^ ~ flicker , où Tfl,Cker est égal à3 chosen such that we check 2- J Z ^ ~ flicker, where T fl , Ck er is equal to
;=l ιι=r,g,b l'inverse de la fréquence de scintillement.= l ιι = r, g, b the inverse of the flicker frequency.
Si toutes ces contraintes sont respectées, les trames colorées peuvent être enchaînées de façon complètement aléatoire dans la séquence d'affichage SD. Dans le cas où la lumière émise n'est émise par la boîte à lumière pour une trame colorée que pour une fraction du temps trame alloué à cette trame colorée, les contraintes précédentes s'écrivent un peu différemment pour la balance des couleurs. C'est notamment le cas dans les afficheurs dont le procédé d'adressage est basé sur un découpage du temps caractéristique de chaque trame colorée trame en trois périodes :If all these constraints are respected, the colored fields can be chained completely randomly in the SD display sequence. In the case where the light emitted is emitted by the light box for a colored frame only for a fraction of the frame time allocated to this colored frame, the preceding constraints are written a little differently for the color balance. This is particularly the case in displays whose addressing method is based on a breakdown of the characteristic time of each frame color frame in three periods:
Dans ce cas, dans l'équation sur les temps caractéristiques donnée plus haut qui permet d'obtenir une balance équilibrée des couleurs, il faut prendre en compte le temps réel alloué dans chaque trame colorée à Péclairement de la matrice. Si on note tain le temps d'allumage de la boîte à lumière sur le temps trame tin associé à une trame colorée, cette équation devient : ta1 r + ta2r + ta3r = ta1 g + ta2g + ta3g = ta1 b + ta2b + ta3b. Un procédé d'adressage selon l'invention qui vient d'être expliquée et dont des exemples d'implémentation ont été donnés en relation avec les figures 1 à 7, permet donc, en agissant sur la succession des couleurs des trames et/ou leur durée d'affichage, et éventuellement sur la puissance lumineuse émise par la boîte à lumière de l'afficheur, de rendre imperceptible ou quasiment imperceptible la rupture des couleurs.In this case, in the characteristic time equation given above which makes it possible to obtain a balanced balance of the colors, it is necessary to take into account the real time allocated in each colored frame to the brightness of the matrix. If we denote t a in the lighting time of the light box on the weft time tin associated with a colored frame, this equation becomes: t a 1 r + t a 2r + t a 3r = t a 1 g + t a 2g + t a 3g = t a 1b + t a 2b + t a 3b. An addressing method according to the invention which has just been explained and whose implementation examples have been given in relation to FIGS. 1 to 7, thus makes it possible, by acting on the succession of colors of the frames and / or their duration of display, and possibly on the light power emitted by the light box of the display, to make imperceptible or almost imperceptible the color break.
La figure 8 donne un aperçu général d'un procédé d'adressage avec une étape d'arrangement 100 des trames colorées selon l'invention : après un paramétrage 100.1 de la formation de la séquence d'affichage (type d'arrangement (succession aléatoire des couleurs et/ou durée d'affichage aléatoire), périodicité d'un motif aléatoire, puissance lumineuse aléatoire), les trames colorées de la séquence vidéo SV reçue en entrée sont ré-arrangées dans une étape 100.2 de formation de la séquence d'affichage SD, en fonction de ces options d'implémentation choisies, et des contraintes imposées : une séquence d'affichage SV est formée dans une étape 100.2, le cas échéant avec le concours 100.3 d'un générateur pseudo-aléatoire pour fournir des temps caractéristiques des trames colorées : fréquence de répétition d'un motif aléatoire, valeurs minimum et maximum des durées, balance des couleurs. On obtient alors en sortie une séquence d'affichage SD qui est appliquée sur l'afficheur LCD 1 , associée à un mode de commande CBAL correspondant de la boîte à lumière 2 : succession des couleurs, durée d'éclairage, puissance d'éclairage.FIG. 8 gives a general overview of an addressing method with an arrangement step 100 of the colored frames according to the invention: after a parameterization 100.1 of the formation of the display sequence (type of arrangement (random succession colors and / or random display duration), periodicity of a random pattern, random luminous power), the colored fields of the video sequence SV received at the input are re-arranged in a step 100.2 of forming the sequence of SD display, according to these chosen implementation options, and imposed constraints: an SV display sequence is formed in a step 100.2, if necessary with the concurrence 100.3 of a pseudo-random generator to provide characteristic times colored fields: frequency of repetition of a random pattern, minimum and maximum values of durations, color balance. An SD display sequence is then output, which is applied to the LCD display 1, associated with a corresponding CBAL control mode of the light box 2: color succession, lighting duration, lighting power.
L'invention qui vient d'être décrite au moyen de quelques exemples non limitatifs permet d'améliorer la qualité d'affichage des afficheurs à cristaux liquides du type à adressage séquentiel couleur, et est applicable à toute la gamme des écrans à vision directe. The invention which has just been described by means of a few nonlimiting examples makes it possible to improve the display quality of liquid crystal displays of the sequential color addressing type, and is applicable to the whole range of direct vision screens.

Claims

REVENDICATIONS
1. Procédé d'adressage d'un afficheur à cristaux liquides (1) en séquentiel couleur, à partir d'une séquence vidéo (SV) de trames colorées successives (fRi , fGi f B 1 ,...), comprenant une étape d'arrangement aléatoire ou pseudo-aléatoire (100) desdites trames colorées de ladite séquence vidéo (SV), pour fournir une séquence d'affichage (SD) de trames colorées à appliquer sur ledit afficheur, caractérisé en ce que ledit arrangement aléatoire est tel que ladite séquence d'affichage (SD) comprend une succession de paquets1. A method of addressing a liquid crystal display (1) in color sequential, from a video sequence (SV) of successive color frames (fRi, fGi f B 1, ...), comprising a step random or pseudo-random arrangement (100) of said colored frames of said video sequence (SV), for providing a display sequence (SD) of colored frames to be applied on said display, characterized in that said random arrangement is such that said display sequence (SD) comprises a succession of packets
(p1 , p2,...) de n trames colorées, n entier au moins égal à 3, chaque paquet étant associé à une paire de couleurs primaires, comprenant une première couleur primaire et une deuxième couleur primaire, les trames colorées de rang impair dans un paquet étant des trames colorées correspondant à ladite première couleur, les trames colorées de rang pair dans le paquet étant des trames colorées correspondant à ladite deuxième couleur.(p1, p2, ...) n colored frames, n integer at least 3, each packet being associated with a pair of primary colors, comprising a first primary color and a second primary color, the odd-rank colored frames in a packet being colored fields corresponding to said first color, the even-rank colored fields in the packet being colored fields corresponding to said second color.
2. Procédé d'adressage d'un afficheur selon la revendication 1 , caractérisé en ce que ladite étape d'arrangement aléatoire comprend une attribution aléatoire ou pseudo-aléatoire de durée2. A method of addressing a display according to claim 1, characterized in that said step of random arrangement comprises a random assignment or pseudo-random duration
(trï , tb1 ,... ) de chacune desdites trames colorées.(trï, tb1, ...) of each of said colored fields.
3. Procédé d'adressage d'un afficheur selon la revendication 1 ou 2, chaque trame colorée comprenant une phase d'éclairage de l'afficheur par une boîte à lumière (2) dans une couleur primaire correspondante, caractérisé en ce que le niveau de puissance lumineuse émis par ladite boîte à lumière dans la phase d'éclairage associée à chacune desdites trames colorées de la séquence d'affichage SD est aléatoire ou pseudo-aléatoire.3. A method of addressing a display according to claim 1 or 2, each color frame including a lighting phase of the display by a light box (2) in a corresponding primary color, characterized in that the level the light power emitted by said light box in the lighting phase associated with each of said colored fields of the display sequence SD is random or pseudo-random.
4. Procédé d'adressage d'un afficheur selon la revendication 2, dans lequel le niveau de puissance de lumière de chaque trame colorée est tel que la puissance lumineuse reconstituée sur l'afficheur correspond à un blanc achromatique. 4. A method of addressing a display according to claim 2, wherein the light power level of each color frame is such that the light power reconstituted on the display corresponds to an achromatic white.
5. Procédé d'adressage selon l'une des revendications 1 à 4, caractérisé en ce que la nième trame colorée d'un paquet de la séquence d'affichage et la première trame colorée du paquet suivant de ladite séquence sont associées à des couleurs primaires différentes.5. Addressing method according to one of claims 1 to 4, characterized in that the nth color frame of a packet of the display sequence and the first color frame of the next packet of said sequence are associated with colors. different primary.
6. Procédé d'adressage selon l'une des revendications 1 à 5, dans lequel n égal 3 ou 4.6. Addressing method according to one of claims 1 to 5, wherein n is 3 or 4.
7. Procédé d'adressage selon l'une quelconque des revendications 1 à 6, caractérisé en ce que ladite étape aléatoire comprend la répétition périodique d'un motif aléatoire.7. Addressing method according to any one of claims 1 to 6, characterized in that said random step comprises the periodic repetition of a random pattern.
8. Procédé d'adressage selon la revendication 7, caractérisé en ce que la périodicité du motif aléatoire est telle que la somme des durées des temps des trames colorées dudit motif aléatoire est inférieur ou égal à l'inverse d'une fréquence de scintillement. 8. Addressing method according to claim 7, characterized in that the periodicity of the random pattern is such that the sum of the times of the color frames of said random pattern is less than or equal to the inverse of a flicker frequency.
9. Procédé d'adressage selon la revendication 2, dans lequel la durée de chaque trame colorée est choisie aléatoirement dans un intervalle de valeurs comprises entre une valeur minimum (Tmin) correspondant à un temps de stabilisation minimum du cristal liquide et une valeur maximum prédéterminée (Tmax). 9. Addressing method according to claim 2, wherein the duration of each color frame is randomly selected in a range of values between a minimum value (T min ) corresponding to a minimum stabilization time of the liquid crystal and a maximum value. predetermined (T max ).
10. Procédé d'adressage selon la revendication 9, dans lequel la somme des durées des trames colorées dans chaque couleur primaire d'une séquence de 3 paquets successifs, est égale pour chacune des couleurs primaires.10. Addressing method according to claim 9, wherein the sum of the durations of the colored frames in each primary color of a sequence of 3 successive packets is equal for each of the primary colors.
11. Procédé d'adressage selon la revendication 9, dans lequel la somme des durées d'éclairage de l'afficheur dans chaque couleur primaire d'une séquence de 3 paquets successifs (p1 , p2, p3), est égale pour chacune des couleurs primaires.11. Addressing method according to claim 9, wherein the sum of the illumination duration of the display in each primary color of a sequence of 3 successive packets (p1, p2, p3) is equal for each of the colors. primary.
12. Procédé d'adressage selon la revendication 9, dans lequel les durées (tin) des trames colorées sont telles que sur une séquence périodique de 3 paquets successifs (p1 , p2, p3), la somme totale des durées des trames colorées est inférieure ou égale à une durée prédéterminée correspondant à l'inverse d'une fréquence minimum de scintillement.12. Addressing method according to claim 9, wherein the duration (tin) of the color frames are such that on a periodic sequence of 3 successive packets (p1, p2, p3), the total sum of the durations of the colored fields is less than or equal to a predetermined duration corresponding to the inverse of a frequency minimum of flicker.
13. Afficheur à cristaux liquides du type à adressage séquentiel des couleurs, caractérisé en ce qu'il comprend un dispositif d'adressage mettant en œuvre un procédé selon l'une quelconque des revendications précédentes. 13. A liquid crystal display of the sequential color addressing type, characterized in that it comprises an addressing device implementing a method according to any one of the preceding claims.
EP07857922.4A 2006-12-22 2007-12-20 Method for addressing an lcd display in colour sequential mode Not-in-force EP2097893B1 (en)

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FR0611257A FR2910684B1 (en) 2006-12-22 2006-12-22 METHOD FOR ADDRESSING A LIQUID CRYSTAL DISPLAY IN COLOR SEQUENTIAL MODE.
PCT/EP2007/064301 WO2008077873A1 (en) 2006-12-22 2007-12-20 Method for addressing an lcd display in colour sequential mode

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MX2012012034A (en) 2010-04-16 2013-05-30 Flex Lighting Ii Llc Front illumination device comprising a film-based lightguide.
WO2011130715A2 (en) 2010-04-16 2011-10-20 Flex Lighting Ii, Llc Illumination device comprising a film-based lightguide
US9275585B2 (en) * 2010-12-28 2016-03-01 Semiconductor Energy Laboratory Co., Ltd. Driving method of field sequential liquid crystal display device
WO2016166199A1 (en) * 2015-04-14 2016-10-20 Koninklijke Philips N.V. Device and method for improving medical image quality

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JP4068317B2 (en) * 2001-07-27 2008-03-26 Necディスプレイソリューションズ株式会社 Liquid crystal display
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EP2097893B1 (en) 2018-08-08
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FR2910684B1 (en) 2009-04-17
WO2008077873A1 (en) 2008-07-03
US20100019999A1 (en) 2010-01-28

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