EP0047692A2 - Method of generating control signals for a plasma panel, and plasma panel controlled by signals generated according to this method - Google Patents

Abstract

This method consists in: - applying to one of the electrodes of one of the networks of electrodes of the panel a selection voltage (Vx1) and to the other electrodes of this network a voltage of non-selection (Vx2); - to apply simultaneously to each electrode of the other network a writing (Vy1), or erasing (Vy2) voltage. Application to the display of successive images, of television type for example, by plasma panel of alternative type.

Description

The present invention relates to a method for generating the control signals of an alternating type plasma panel. It also relates to plasma panels of the alternative type controlled by signals developed by this process.

Plasma panels of the alternative type are well known in the prior art, in particular by French patent application No. 78.04893, published under No. 2,417,848, in the name of THOMSON-CSF and by the article published in the "THOMSON-CSF Technical Review", June 1978, volume 10, N 2, pages 249 to 275.

These panels include a large number of cells arranged in a matrix form. Each cell is formed by the gas space located at the intersection of two electrodes belonging to two networks of orthogonal electrodes and is subjected to control signals constituted by the difference of the voltages applied to the two electrodes between which it is located.

Among the control signals, mention may be made of the registration signals which cause the cells to ignite, the erasure signals which extinguish the cells and the maintenance signals which keep the cells in their initial state, namely the state off, i.e. the status on.

Unlike the maintenance signals which are applied to all the electrodes of the panel to ensure the visualization of the information entered, the recording and erasing signals are selective signals which must not cause recording and erasure only for the selected cells.

To this end, any cell C _xy is only registered if its two electrodes, x and y, receive adequate voltages, V _x and V, which make it possible to obtain the signal at the terminals of this cell and of it alone. of registration.

It is the same to obtain the erasure of cell C _xy .

According to the prior art, the voltages V _x and V y making it possible to obtain the inscription of the cell C _x y differ from the voltages V 'x and V' y making it possible to obtain its erasure.

It is therefore not possible, according to the prior art, to carry out simultaneously the selective writing and erasing of cells having an electrode in common, that is to say of cells located on the same row or on the same column of the panel.

A problem then arises with plasma panels of the alternative type for displaying successive images, television type images for example.

Indeed, it is not possible to register the images quickly, that is to say with a duration of registration of each line of the order of 20} _l s, and to make the images succeed one another quickly , that is to say practically without interruption.

It should be remembered that the plasma panels of the alternative type keep in memory each recorded image. Since you cannot simultaneously selectively write and erase cells for a given line, you must erase the panel before writing a new image.

• - soit effacer tout le panneau à la fois, puis inscrire une nouvelle image, ligne après ligne. L'inconvénient est que les différentes lignes du panneau n'ont pas le même temps d'affichage. La luminance varie donc d'une ligne à l'autre et ce défaut de l'image est d'autant plus gênant qu'on change d'image plus rapidement ;
• - soit effacer une, ou quelques, lignes du panneau et puis les ré-inscrire ligne après ligne. L'inconvénient est alors que le temps d'inscription d'une image est fortement augmenté, voire doublé dans le cas où on efface une seule ligne avant de la ré-inscrire. Il faut alors 2 x 20 ps environ pour inscrire une ligne.

We can :

• - either erase the whole panel at once, then write a new image, line after line. The disadvantage is that the different lines of the panel do not have the same display time. The luminance therefore varies from one line to another and this defect in the image is all the more annoying when the image changes more quickly;
• - either delete one or a few lines from the panel and then re-register them line after line. The disadvantage is that the registration time of an image is greatly increased, or even doubled in the case where a single line is deleted before re-registering it. It then takes about 2 x 20 ps to register a line.

The present invention makes it possible to solve the problem of displaying images using an alternating plasma panel by eliminating the drawbacks of variable luminance and increased writing time, and this without modifying the memory effect of the panels. plasma of the alternative type.

• - à appliquer à l'une des électrodes de l'un des réseaux une tension dite de sélection et aux autres électrodes de ce réseau une tension dite de non-sélection ;
• - à appliquer simultanément à chaque électrode de l'autre réseau une tension choisie parmi au moins deux tensions dites d'inscription et d'effacement ;

la forme, l'amplitude et la durée de ces diverses tensions étant telles que les cellules recevant sur une électrode la tension de sélection et sur l'autre électrode la tension d'inscription ou d'effacement soient inscrites ou effacées, alors que les cellules recevant sur une électrode la tension de non-sélection soient toutes entretenues dans leur état initial quelle que soit la tension appliquée sur l'autre électrode.The present invention relates to a method for generating the control signals of an alternating type plasma panel which comprises:

• - applying to one of the electrodes of one of the networks a so-called selection voltage and to the other electrodes of this network a so-called non-selection voltage;
• - applying simultaneously to each electrode of the other network a voltage chosen from at least two so-called write and erase voltages;

the form, amplitude and duration of these various voltages being such that the cells receiving on one electrode the selection voltage and on the other electrode the writing or erasing voltage are written or erased, while the cells receiving on one electrode the non-selection voltage are all maintained in their initial state regardless of the voltage applied to the other electrode.

With the present invention, it is possible to carry out for a given row (or column) inscriptions and selective erasures. It is no longer necessary to erase the panel to change the image. We display an image on the panel, line after line (or column after column), and then we display a new image by making selective entries and deletions for each line (or each column). There is no longer any variable luminance of the image and the writing time of a line is only 20 us.

• - Les figures 1 et 4, une représentation schématique de quelques cellules d'un panneau à plasma ;
• - Les figures 2a à 2h et 3a à 3h, les tensions qui, selon l'art antérieur, sont appliquées aux électrodes des cellules de la figure 1, et les signaux de commande reçus par ces cellules , pour provoquer respectivement l'incription et l'effacement de l'une des cellules ;
• - Les figures 5a à 5h, les tensions qui, selon l'invention, sont appliquées aux électrodes des cellules de la figure 4, et les signaux de commande reçus par ces cellules .

Other objects, characteristics and results of the invention will emerge from the following description, given by way of nonlimiting example and illustrated by the appended figures which represent:

• - Figures 1 and 4, a schematic representation of some cells of a plasma panel;
• - Figures 2a to 2h and 3a to 3h, the voltages which, according to the prior art, are applied to the electrodes of the cells of Figure 1, and the control signals received by these cells, to respectively cause the entry and l 'deletion of one of the cells;
• - Figures 5a to 5h, the voltages which, according to the invention, are applied to the electrodes of the cells of Figure 4, and the control signals received by these cells.

In the different figures, the same references designate the same elements, but, for reasons of clarity, the dimensions and proportions of the various elements are not observed.

FIG. 1 schematically represents four cells C ₁₁ , C ₁₂ , ^C ₂₁ and C ₂₂ of a plasma panel which are located at the intersections of two horizontal electrodes x ₁ and x ₂ and two vertical electrodes y ₁ and y2.

• - la tension V_x1 a une amplitude V₁ et une durée t₃ - t₁;
• - la tension V_x2 à la même amplitude V₁ et une durée t₂ - t₁ inférieure à ^t ₃ - t₁;
• - la tension V_y1 a une partie négative d'amplitude V₂ inférieure à V₁ et de durée t₃ - t₂ suivie par une partie positive d'amplitude V₁ et de durée t₅ - ^t ₄ ;
• - enfin, la tension Vy₂ a une amplitude V et une durée t₅ - t₄.

Suppose that we want to enter cell C 11. Figures 2a, b, c, d represent the voltages V _xl , V _{x2 '} V _y1 , Vy _2' which are applied, according to the prior art, to the electrodes x ₁ , x ₂ , y ₁ , _Y2 so that only cell C ₁₁ is entered:

• - the voltage V _x1 has an amplitude V ₁ and a duration t ₃ - t ₁ ;
• - the voltage V _x2 at the same amplitude V ₁ and a duration t ₂ - t ₁ less than ^t ₃ - t ₁ ;
• the voltage V _y1 has a negative part of amplitude V ₂ less than V ₁ and of duration t ₃ - t ₂ followed by a positive part of amplitude V ₁ and of duration t ₅ - ^t ₄ ;
• - finally, the voltage Vy ₂ has an amplitude V and a duration t ₅ - t ₄ .

FIGS. 2e, f, g, h show the control signals applied to cells C ₁₁ , C ₁₂ , ^C _{21 '} ^C ₂₂ and which result from the difference in voltages applied to the two electrodes between which each cell is located. .

We note the appearance at the terminals of cell C ₁₁ of t ₂ to t ₃ of a voltage of amplitude V ₁ + V ₂ sufficient to cause the inclusion of C ₁₁ .

On the contrary on the other cells, the amplitude of the voltage does not exceed V ₁ , which is insufficient to cause their inscription.

Only cell C ₁₁ is therefore entered.

It is noted that for the four signals applied to the cells which are represented in FIGS. 2e at 2 h, there is at time t ₁ a rising edge of amplitude V ₁ and at time t ₄ a falling edge at - V ₁ ce which corresponds to the characteristics of the maintenance signals and therefore allows viewing of the information already entered on the sign.

• - la tension V_x1 varie, à partir de l'instant t₄ sensiblement linéairement en fonction du temps de O à V₁ puis se stabilise à V₁ et redescend à 0 au temps t₅. L'utilisation d'une telle tension pour effacer une cellule a été décrite dans la demande de brevet n° 78.04893 déjà citée ;
• - la tension V_x2 est constamment nulle ;
• - la tension V_y1 a une partie négative d'amplitude Vide t₁ à t₂ suivie par une partie positive d'amplitude Vide t₃ à t₄ ;
• - la tension Vy2, ne diffère de V_y1 que par le fait que sa partie positive est plus longue et dure de t₃ à t₅.

Figures 3a, b, c, d represent the voltages V _x1 , V _x2 , V _y1 , V _y2 which are applied according to the prior art, to the electrodes x ₁ , x ₂ , Y ₁ , y ₂ so that only cell C ₁₁ is deleted. These tensions will be described with reference to the instants t ₁ to t ₅ which follow one another on the time axis, 0 t, in the order of t ₁ to t ₅ :

• - the voltage V _x1 varies, from time t ₄ substantially linearly as a function of time from O to V _1, then stabilizes at V ₁ and drops back to 0 at time t ₅ . The use of such a voltage to erase a cell has been described in patent application No. 78.04893 already cited;
• - the voltage V _x2 is constantly zero;
• - the voltage V _y1 has a negative part of Vac amplitude t ₁ to t ₂ followed by a positive part of Vac amplitude t ₃ to t ₄ ;
• - the voltage Vy2, differs from V _y1 only by the fact that its positive part is longer and lasts from t ₃ to t ₅ .

Figures 3e to 3h show the control signals applied to cells C ₁₁ , C ₁₂ , C ₂₁ , C ₂₂ . Only the signal applied to cell C ₁₁ allows erasure thanks to the linear growth part of the voltage from O to Empty at time t ₄ at time t ₅ .

It is noted that in this case also the four signals applied to the cells carry out the maintenance of the cells because of the rising edge towards V ₁ existing at time t ₁ and the falling edge towards - V ₁ existing at time t ₃ . Only cell C ₁₁ is deleted, the other cells are maintained in their initial state.

It is noted that the voltages V _x1 and V _y1 making it possible to obtain the registration of cell C ₁₁ differ from the voltages V _x1 and V _y1 making it possible to obtain its erasure. To realize this, it suffices to compare Figures 2a and 3a, and 2c and 3c.

In conclusion and as has already been said in the introduction to the description, it is not possible, according to the prior art, to simultaneously carry out selective recording and erasure of cells having an electrode in common. For example, it is not it is possible to write C ₁₁ and simultaneously delete C ₁₂ or C _{21. We} have seen the problem that this entailed for producing the display of successive images with plasma panels of the alternative type.

• Figure 4 schematically represents six cells C ₁₁ , C ₁₂ , C ₁₃ , C _{21 '} C _22' C ₂₃ of a plasma panel which are located at the intersections of two horizontal electrodes x ₁ and x ₂ and three electrodes vertical y ₁ , y ₂ and y ₃ .
• FIGS. 5a to 5e serve to illustrate the method for developing the control signals according to the invention. These figures represent the voltages V _x1 , V _x2 , V _y1, Vy ₂ and Vy ₃ which are applied to the electrodes x ₁ , x ₂ , y ₁ , Y ₂ and y ₃ so as to cause, for example, at both, the registration of C ₁₁ , the deletion of C ₁₂ and the maintenance in its initial state of C13, as well as the maintenance of the other cells C ₂₁ , C ₂₂ and C ₂₃ in their initial state.
• FIGS. 5f to 5k represent the resulting voltages obtained at the terminals of cells C ₁₁ , ^C ₁₂ , ^C _{13 '} ^C _21' C ₂₂ , C ₂₃ .

In FIGS. 5a to 5k, the selective part of the voltages has been shown in broken lines, that is to say that which is not identical for all the electrodes and all the cells of the panel and which extends in the 'example chosen from t ₃ to t ₄ . We have located on the time axis, O t, the instants t ₁ to t ₆ which follow each other in order.

In FIGS. 5a to 5k, the non-selective part of the voltages, which is identical for all the electrodes and all the cells of the panel, and which aims to apply to all the cells a maintenance signal constituted, is shown in solid lines. a positive part of amplitude V ₁ and a negative part of amplitude V ₁ .

In the example shown in FIGS. 5a to 5e, the non-selective part is obtained by providing a positive part of amplitude V ₁ from t, to t ₂ for the voltages Vy ₁ , Vy ₂ and Vy ₃ and by providing a positive part of vacuum amplitude t ₅ to t ₆ for voltages V _x1 and V _x2 .

It would of course be possible to proceed differently, for example, by providing a negative part of amplitude V ₁ from t ₅ to t ₆ for the voltages V _y1 , Vy ₂ and Vy ₃ and by applying a zero voltage between the instants t ₅ and t ₆ for the voltages V _x1 and V _{x2 '}

• - à appliquer à l'électrode x₁ qui correspond à la ligne sur laquelle on veut réaliser, simultanément et sélectivement, une inscription, un effacement et l'entretien d'une cellule dans son état initial, une tension dite de sélection. Sur la figure 3a, cette tension varie à partir de l'instant t₃ sensiblement linéairement en fonction du temps de 0 à V₁ puis se stabilise à V₁ et redescend à 0 au temps ^t ₄ ;
• - à appliquer à l'autre électrode x₂ une tension dite de non-sélection qui sur la figure 5b est nulle de t₃ à t₄ ;
• - à appliquer toujours de ^t ₃ à ^t ₄ ^:
  • . sur l'électrode y₁, une tension dite d'inscription de façon à inscrire la cellule C₁₁. Sur la figure 5c, cette tension est négative et d'amplitude V_I ;
  • . sur l'électrode y₂, une tension dite d'effacement de façon à effacer la cellule C₁₂. Sur la figure 5d, cette tension est nulle ;
  • . sur l'électrode y₃, une tension dite d'entretien pour entretenir la cellule C₁₃ dans son état initial. Sur la figure 5e, cette tension est positive et d'amplitude V₁.

The method according to the invention consists:

• - To apply to the electrode x ₁ which corresponds to the line on which we want to carry out, simultaneously and selectively, an entry, an erasure and the maintenance of a cell in its initial state, a so-called selection voltage. In FIG. 3a, this voltage varies from instant t ₃ substantially linearly as a function of time from 0 to V _1, then stabilizes at V ₁ and drops back to 0 at time ^t ₄ ;
• - applying to the other electrode x ₂ a so-called non-selection voltage which in FIG. 5b is zero from t ₃ to t ₄ ;
• - always apply from ^t ₃ to ^t ₄ ^:
  • . on the electrode y ₁ , a so-called registration voltage so as to register the cell C ₁₁ . In FIG. 5c, this voltage is negative and of amplitude V _I ;
  • . on the electrode y ₂ , a so-called erase voltage so as to erase the cell C ₁₂ . In FIG. 5d, this voltage is zero;
  • . on the electrode y ₃ , a so-called maintenance voltage for maintaining the cell C ₁₃ in its initial state. In FIG. 5e, this voltage is positive and of amplitude V ₁ .

The form, amplitude and duration of the various selection, non-selection, registration, erasure or maintenance voltages are chosen so that the cells receiving the selection voltage on an electrode and the other electrode the voltage of registration, erasure or maintenance are registered, erased or maintained in their initial state. On the contrary, the cells receiving the non-selection voltage on one electrode must be maintained in their initial state whatever the voltage applied to the other electrode of these cells.

This is what happens with the voltages shown in broken lines in FIGS. 5a to 5e and which are given only by way of example.

• - que la cellule C ₁₁ est inscrite, car elle reçoit entre t₃ et t₄ une tension élevée qui atteint 2V ₁ ;
• - que la cellule C₁₂ est effacée, car elle reçoit de t₃ à t₄ une tension qui croît linéairement en fonction du temps de 0 à V_I ;
• - que les autres cellules C13, C_21' C₂₂ et C₂₃ sont entretenues dans leur état initial car elles reçoivent des tensions représentées sur les figures 5h à 5k qui sont successivement négatives, d'amplitude V_I et positives, d'amplitude V_l, mais qui n'atteignent jamais une amplitude suffisante pour permettre l'inscription et ne comportent pas non plus de zone à croissance linéaire de la tension qui permette l'effacement.

We observe indeed by observing Figures 5f to 5k:

• - that cell C ₁₁ is registered, since it receives between t ₃ and t ₄ a high voltage which reaches 2V ₁ ;
• - that cell C ₁₂ is deleted, since it receives from t ₃ to t ₄ a voltage which increases linearly as a function of time from 0 to V _I ;
• - that the other cells C13, C _{21 '} C ₂₂ and C ₂₃ are maintained in their initial state because they receive voltages shown in Figures 5h to 5k which are successively negative, of amplitude V _I and positive, of amplitude V _l , but which never reach a sufficient amplitude to allow the inscription and also do not include a linear growth zone of the tension which allows the erasure.

• - les électrodes d'un réseau reçoivent une tension dite de sélection ou une tension dite de non-sélection ;
• - les électrodes de l'autre réseau reçoivent une tension dite d'inscription, d'effacement, d'entretien ou toute autre tension mettant la cellule dans un état donné.

It can be seen that with the method according to the invention:

• the electrodes of a network receive a so-called selection voltage or a so-called non-selection voltage;
• - The electrodes of the other network receive a voltage called registration, erasure, maintenance or any other voltage putting the cell in a given state.

One carries out, simultaneously and selectively, for a given row or column, the recording, the deletion and the maintenance of the cells.

In the prior art, on the contrary, the various cycles, for writing and erasing for example, are carried out separately. The electrodes of each network receive, during a given cycle, only two types of voltage, selection or non-selection, specific to this cycle.

As seen in the introduction to the description, the method according to the invention makes it possible to solve the problem of displaying successive images by plasma panel.

If from one image to another, there is no area of the image which remains unchanged, it is not necessary to carry out, simultaneously and selectively, inscriptions, erasures and maintenance of cells in their initial state. It suffices to carry out selective registrations and erasures. The electrodes of one of the networks therefore receive a voltage chosen only from the ins voltages cription or erasure.

If, on the other hand, from one image to another, certain image zones remain unchanged, it is useful to simultaneously and selectively carry out inscriptions, erasures and maintenance of cells in their initial state.

As regards the control circuits of the plasma panel allowing the implementation of this process, they follow directly from those described by the patent application No. 78.04893 already cited.

Claims (4)

1. Method for developing the control signals of an alternating type plasma panel, these control signals being applied between two electrodes belonging to two networks of orthogonal electrodes and the gas space located at the intersection of two electrodes belonging to different networks constituting a panel cell, characterized in that it consists: - applying to one of the electrodes of one of the networks a so-called selection voltage (Vxl) and to the other electrodes of this network a so-called non-selection voltage (V _x2 ); - applying simultaneously to each electrode of the other network a voltage chosen from at least two so-called _write (V _y1 ) and erase (V _y2 ) voltages; the form, the amplitude and the duration of these various voltages being such that the cells receiving on one electrode the selection voltage and on the other electrode the writing or erasing voltage are written or erased, while the cells receiving on one electrode the non-selection voltage are all maintained in their initial state regardless of the voltage applied to the other electrode. 2. Method according to claim 1, characterized in that the voltage applied to each electrode of the other network is chosen from three voltages called registration (V _y1 ), erasure (V _y2 ) or maintenance (Vy3 ), the cells receiving the maintenance voltage on one electrode and the selection or non-selection voltage on the other electrode being maintained in their initial state. 3. Method according to one of claims 1 or 2, characterized in that: - the selection voltage (V _x1 ) increases linearly as a function of time from 0 to V ₁ then stabilizes at V _I before returning to O; - the non-selection voltage (V _x2 ) is zero; - the writing voltage (V _y1 ) is negative with amplitude V ₁ ; - the erasing voltage (V _y2 ) is zero; - the maintenance _tention (V _y3 ) is positive with amplitude V ₁ . 4. Plasma panel of alternative type, characterized in that it is controlled by control signals developed by the method according to one of claims 1 to 3.

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