EP1120772A1 - Regenerierung der Anoden einer flachen Anzeigetafel - Google Patents

Regenerierung der Anoden einer flachen Anzeigetafel Download PDF

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Publication number
EP1120772A1
EP1120772A1 EP01410006A EP01410006A EP1120772A1 EP 1120772 A1 EP1120772 A1 EP 1120772A1 EP 01410006 A EP01410006 A EP 01410006A EP 01410006 A EP01410006 A EP 01410006A EP 1120772 A1 EP1120772 A1 EP 1120772A1
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EP
European Patent Office
Prior art keywords
regeneration
screen
display
anodes
phases
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Withdrawn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
EP01410006A
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English (en)
French (fr)
Inventor
Axel Jäger
Didier Colas
Jean-Francois Peyre
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.)
Pixtech SA
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Pixtech SA
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Publication date
Application filed by Pixtech SA filed Critical Pixtech SA
Publication of EP1120772A1 publication Critical patent/EP1120772A1/de
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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

Definitions

  • the present invention relates to a flat display screen of the type comprising an anode provided with luminescent elements likely to be aroused, for example, by bombardment electronic.
  • This electronic bombardment requires that the elements luminescent are polarized and can come from microtips, layers with low extraction potential or a thermionic source.
  • Figure 1 shows, very schematically, the functional structure of a color microtip flat screen to which the present invention relates.
  • Such a microtip screen essentially consists a cathode 1 with microtips 2 and a grid 3 provided with holes 4 corresponding to the locations of the microtips 2.
  • the cathode 1 is placed opposite a cathodoluminescent anode 5.
  • the cathode associated with the grid is carried by a first plate (not shown), for example glass.
  • the anode is itself carried by a second glass plate or substrate (not shown).
  • the anode or cathode plate is transparent. In the case of a transparent cathode screen, the anode is provided with a reflective surface towards the cathode.
  • Cathode 1 is organized in columns and is made up independently addressable cathode conductors others.
  • Grid 3 is organized into lines and a layer insulator (not shown) is interposed between the conductors cathode and grid. The intersection of a grid line and of a column of the cathode generally defines a pixel.
  • Such a device uses the electric field created between the cathode and the grid so that electrons are extracted from microtips 2 to phosphor elements 6 of anode 5.
  • anode 5 is, for example, provided with alternating bands of phosphor elements 6R, 6G, 6B, each corresponding to a color (blue, red, green). The strips are separated from each other by an insulator (not represented).
  • the phosphor elements 6R, 6G, 6B are deposited on electrodes 9R, 9G, 9B, made up of corresponding bands a conductive layer, for example transparent, such than indium tin oxide (ITO).
  • ITO indium tin oxide
  • One drawback of conventional color screens is that, when polarizing a set of bands of one color given, there is a parasitic emission of the other two colors. Thus, if the lighting set point of a given pixel corresponds, for example, to pure or saturated red, we observe the screen a parasitic emission of blue or green.
  • Figure 1 represents schematically and in section along a row of the grid 3, a pixel of the screen.
  • Figure 1 represents schematically and in section along a row of the grid 3, a pixel of the screen.
  • microtips 2 have been shown for clarity while in practice there are several thousand per screen pixel.
  • the conductive strips 9R carrying the 6R red phosphor elements are addressed by being polarized at a positive potential of several hundred volts per compared to cathode 1, while the conductive strips 9G and 9B carrying, respectively, the green phosphor elements 6G and blue 6B are at rest being at zero potential with respect to the cathode.
  • FIGS. 2 and 3 These figures represent, in the form of chronograms, a classic example of control of a flat display screen.
  • This example of a classic screen control mode color consists of forming several images per second, per example 50 to 60 frames per second, that is to say that we have with a duration of approximately 20 ms to form each image frame. This duration is called frame duration T (FIG. 2).
  • lines L1, ..., Li-1, Li, Li + 1, ..., Ln are sequentially raised to a high potential so that all the pixels of the corresponding line are likely to be excited at some point.
  • the column conductors of the cathodes are placed at potentials which give the corresponding pixel the intensity desired light.
  • the luminescence level is adjusted by width modulation pulse during each line excitation time.
  • the present invention aims to improve regeneration of a flat screen display anode by an excitation of microtips without polarization of the anode.
  • the present invention aims to remedy an aging problem premature of the screen that the inventors suppose to come from regeneration.
  • the inventors consider that only the phosphor elements corresponding to the pixels that were lit during a display of an image need to be refreshed, i.e. require residual charge removal they can contain. They consider that the premature aging of the screen comes from the untimely regeneration of regions of screen that are not activated while viewing an image. In this regard, they consider that when regions which have not anode side or cathode side charge are regenerated, causes local pollution by desorbing species from the layers accessible from the anode and the grid cathode. Side grid cathode, electrons falling on it will make desorb species, resulting in accelerated aging of grid cathode pixels and phosphor elements of the anode.
  • the invention plans to reproduce, during periods of anode regeneration, addressing of the image that has just been displayed, so perform a regeneration of the anode or anodes of the screen by excitation selective microtips without polarization of the anode.
  • a first condition that must be respected is to memorize the displayed images (in fact, the instructions for luminance, if any, for each color) during the different subframes so that you can readjust the screen and, in particular, the cathode-grid in the same way during the regeneration subframe.
  • This constraint can be resolved relatively easily by planning to associate, on the screen, means for temporarily storing the displayed images. Size of such memory is perfectly reasonable as far where its shelf life is low and it can be erased by storing the following images.
  • the present invention aims to propose a new regeneration solution which solves these problems and which allows a selective regeneration of the screen regions to respect, as much as possible, the implementation of a regeneration on the areas used for display.
  • the present invention also aims to ensure that this solution be compatible with a reasonable memory size necessary to temporarily store the images displayed in view of regeneration.
  • the present invention aims, in particular, to propose a solution that respects the duration generally dedicated to the phase of regeneration in a conventional display frame.
  • the present invention provides a method for regenerating a cathodoluminescence screen provided with at least one anode suitable for being excited by bombardment electronic in a line scan, consisting in providing regeneration phases during which the anode is at a rest potential, only part of the lines being addressed in a line scan at each regeneration phase, and cathodes being polarized in a state corresponding to that from a previous image.
  • the method consists in memorizing the addressing instructions of the cathodes for displaying an image, with a corresponding frequency at the regeneration frequency of each line.
  • the regeneration phases are interspersed between phases display.
  • a part at less of the anodes is at rest potential during the phases of regeneration.
  • the display phases correspond to sub-frames respectively assigned to the anodes, a regeneration phase being inserted between each sub-frame.
  • the display phases correspond to display frames grouping sub-frames respectively assigned to the anodes, a regeneration phase being inserted between each frame display.
  • all the anodes are, during the regeneration phases, at resting potential.
  • the screen is a color microtip screen.
  • the screen is a monochrome microtip screen.
  • FIG. 4 very schematically shows a example of image I displayed on a flat display screen of the type to which the present invention applies.
  • this picture taken for example only two zones N and N 'have a brightness not zero, which is to say that in all the rest of image I, the phosphor elements of the anode do not receive of electrons.
  • the display of an image I as illustrated by the FIG. 4 is carried out in a conventional manner in an image frame (T, figure 2). For a color screen, this display is performed, to a complete image, in three color subframes.
  • Figure 5 illustrates the regeneration that will take place by implementing an embodiment of the the invention.
  • the image I displayed during a frame is memorized in order to allow a subsequent re-addressing of the cathode columns with corresponding luminescence guidelines to this image for each color.
  • the invention plans to re-address the columns during the phase screen regeneration.
  • a feature of the invention is, to make compatible with addressing the columns in image reproduction previously displayed with the restricted duration of a regeneration before the duration of a display frame, to split the image (or screen) in groups of lines a, b, c.
  • this division of the screen for regeneration is used to regenerate only one group of lines between two images. So, according to the present invention, the regeneration of the entire screen is not performed between each image but requires several images to run completely for the entire screen.
  • the subdivision carried out for regeneration i.e. the number of groups of lines on the screen, depends on the duration available for the regeneration phase and durations necessary for addressing the columns and scanning the lines of a group during this regeneration phase.
  • FIG. 6 represents, in the form of chronograms, line scanning performed during display frames and regeneration phases.
  • each line Ll, L2, L3, L4, L5, L6, L7, L8, L9 was addressed only one times per image frame T1, T2, T3, T4, which corresponds to the case a monochrome screen whose anode has only one plane of elements phosphors.
  • the invention applies also a color screen (or a monochrome screen provided at least two alternating sets of phosphor elements of same color) and that, in this case, each line is in practice addressed, for example for a color screen, three times per frame color, i.e. once per subframe of each color.
  • the embodiment illustrated in FIG. 6 could however match, for a color screen, a variant bet implementation of the invention which would consist in carrying out a period regeneration Td between each color subframe.
  • Tda, Tdb, Tdc regeneration phase is planned, which concerns that a group a, b, c of lines.
  • Each group includes here three lines so each line is addressed for regeneration once in three.
  • all anodes are at rest potential, for example, mass.
  • this contributes to the optimization of regeneration targeted by the invention by allowing targeted regeneration with low energy electrons.
  • the bands of phosphor elements which are addressed accumulate a positive charge which they do not evacuate. Therefore, during a regeneration phase, the electrons emitted by the cathode are attracted by this strip (this anode) who, if she is the only one to have participated in the display, found to have a more positive potential than bands of other colors who are next to him.
  • the other bands if they don't have no positive charge, do not receive (or little by relative to the positively charged band) of regeneration electrons. We therefore obtain a preferential regeneration effect towards the bands addressed during the display phases.
  • An advantage of the present invention is that it allows optimize regeneration phases by avoiding aging premature screens.
  • Another advantage of the present invention is that it does not require any modification of the display itself. Indeed, the invention is implemented during conventional durations allocated to regeneration phases. So the setting work of the present invention is perfectly compatible with compliance with conventional display constraints.
  • the frequency of repetition of the phases of regeneration can be adapted according to screens and applications.
  • the regeneration phases may be spaced, that is to say reproduced at a different frequency that of the images, or close together, that is to say reproduced at the frequency of the color subframes. In each case, this change will lead to a change in the frequency of regeneration of lines according to the invention without necessarily being necessary to modify their distribution by groups.
  • an advantage of this invention is that it minimizes the memory required for the storage of data necessary for regeneration.
  • the present invention is capable of various variants and modifications which will appear to the man of art.
  • the choice of the number of lines per group of regeneration and frequency of regeneration phases depend on the screen and the application.
  • the implementation work of the present invention by program modification display is within the reach of ordinary skill in the art from functional indications given above, using the means conventionally used for addressing screens.
  • each group of lines may include non-successive lines, provided that their respective addresses be modified accordingly.
  • the luminance setpoint is provided by the grid lines and not by the cathode columns, which amounts to making a column scanning, the present invention could easily be transposed.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • General Physics & Mathematics (AREA)
  • Theoretical Computer Science (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
EP01410006A 2000-01-25 2001-01-24 Regenerierung der Anoden einer flachen Anzeigetafel Withdrawn EP1120772A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0000932 2000-01-25
FR0000932A FR2804243B1 (fr) 2000-01-25 2000-01-25 Regeneration d'anodes d'ecran plat de visualisation

Publications (1)

Publication Number Publication Date
EP1120772A1 true EP1120772A1 (de) 2001-08-01

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EP01410006A Withdrawn EP1120772A1 (de) 2000-01-25 2001-01-24 Regenerierung der Anoden einer flachen Anzeigetafel

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US (1) US20010026133A1 (de)
EP (1) EP1120772A1 (de)
JP (1) JP2001242821A (de)
FR (1) FR2804243B1 (de)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0747875A1 (de) * 1995-06-08 1996-12-11 Pixtech S.A. Steuerverfahren für eine flache Anzeigetafel

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0747875A1 (de) * 1995-06-08 1996-12-11 Pixtech S.A. Steuerverfahren für eine flache Anzeigetafel

Also Published As

Publication number Publication date
FR2804243B1 (fr) 2002-04-12
JP2001242821A (ja) 2001-09-07
US20010026133A1 (en) 2001-10-04
FR2804243A1 (fr) 2001-07-27

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