DE9018143U1 - Electronic display device - Google Patents

Description

SPARING · J=TOtI L riH-E?4S*fe UE
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EUROPEAN patent attorneys

Dipl.-lng. Helmut Marsch (1934-1979) PO Box 140443

Dipl.-lng. Klaus Sparing D-40074 Düsseldorf
Dr. rer. nat Wolf Horst Röhl

Dr. rer. nat. Daniela Henseler Phone: (0211) 671034

Fax: (0211) 663420

SPARING, RÖHL, HENSELER · P.O. BOX 140443 · D-40074 DÜSSELDORF 8582542 SpHD Cl

Asulab S.A. Faubourg du Lac 6, CH-2501 Bienne ELECTRONIC DISPLAY DEVICE

The invention relates to an electronic display device which is intended to visualize certain characters, such as in particular alphanumeric characters.

More specifically, it relates to a display device in which the active display means is formed by one or more elements whose optical characteristics can vary in response to an electrical excitation signal, selectively controlled by an electronic control circuit.

In the description below, reference will be made to an electro-optical cell of the liquid crystal type to designate such an element. As will be understood, the invention can also relate, in certain of its characteristics, for example to a display device comprising a group of electroluminescent diodes, more generally designated by the English acronym "LED", or to any other display device corresponding to the above definition.

It is already known, in particular from patent application FR-A-2 458 857, an electronic display device comprising a group of modules formed either by electrodes of a liquid crystal cell or by electroluminescent diodes and having the shape of straight segments arranged adjacent and abutting one another in rows and columns.

SPARING, RÖHL, HEN6ELER*<RETlHELS&trade;«tSSE &Ggr;23 · S'40237 DÜSSELDORF

From a graphical point of view, this device is not entirely satisfactory since it only allows characters to be displayed "in bars", i.e. in the form of lines joined together.

More importantly, this device is severely limited because the modules do not allow for the option of displaying either lowercase or uppercase letters.

Moreover, patent application EP 0 146 285 describes a display device of a different type, i.e. one structured essentially in the form of a dot matrix with η rows and ρ columns (with η equal to 5 and ρ equal to 3 in this example).

The pixels of this matrix, i.e. the most elementary patterns, each of which forms an individually addressable electrode, have been modified relative to the pixels of more conventional dot matrices, solely with the aim of improving resolution. Thus, the designers of this matrix, while necessarily wanting to maintain the quality of low-order matrices (typically 5x3), have attempted to increase the number of pixels. At the time, they therefore quite naturally started from a conventional matrix shape comprising rectangular pixels and in particular square ones, by definition all identical and distributed in a homogeneous manner. The aim they had set themselves led them to divide the pixels into four, by cutting them almost all in a quasi-identical manner using two diagonals. The resulting structure therefore consists essentially of several repeated groups, each consisting of four isosceles triangles. When considering the contour or the envelope of these groups, one can clearly see the behavior of the original rectangles whose reunification forms the quadrupling or lattice of the matrix.

It can therefore be seen that the structure of this device remains in a very uniform and ordered concept with a strict and almost identical repetition of groups and of pixels according to the definition of matrix type displays.

This particular concept of electro-optical display has major disadvantages. The shape of the displayed characters is determined by

Determined from the outset by the matrix scheme of the electrodes or pixels. Starting from a rigid and imposed scheme, the only option the user has is to select the pixels available to him in this predetermined scheme in order to obtain a letter or a number. It is therefore impossible for him to visualize stylized characters, since the capacity of the device in the square grid division is limited from the outset.

It is therefore understood that the device proposed in this patent application, although it addresses the concerns of increasing the resolution of matrix-type display devices by increasing the number of pixels, is nevertheless very limited. The user, and consequently the purchaser of these devices, is looking for characters that are as aesthetic as possible, close to a particular type or personalized writing.

Patent application EP 0 180 685, in particular in its last embodiment, partially addresses this problem by providing a device of a different design. Since the primary objective is to improve the aesthetics of the characters, the designers of this device no longer started from a forced electrode pattern, but from the result to be obtained, namely the letters and numbers themselves, in order to design the electrodes exclusively accordingly.

For this reason, the resulting pixels are irregularly formed and are arranged in a disordered manner without systematic repetition in rows and columns, whereby these pixels mostly have different contours from each other.

This type of device is called a "mosaic" because of its composite type structure, formed by numerous pixels with heterogeneous contours (rounded, straight, angled,...) but complementary to each other and concordant, superimposing each other. It can be seen that no consideration is given to a logical and uniform distribution of pixels or electrodes over the entire surface of the device, unlike the matrix structures defined above. This type of device seems to be the embodiment of the

formation of colored glass pieces that can be found in old windows of places of worship, especially in the West.

This device has major disadvantages.

First of all, it is observed that the fact of stylizing characters leads, in an irreversible way, to an increase in the number of pixels, which very significantly increases the price of the finished and equipped device, to the extent that more complex and "heavy" electronic circuits must be associated with them.

Moreover, the characters obtained suffer from poor definition and have defects formed by dots, as explained below.

Indeed, as shown very schematically in Fig. 2 of the accompanying drawings, spots or markings (denoted by 10) appear on the reproduced characters, as in the case of the "A" shown, whereby these defects significantly impair the appearance and thus the aesthetic quality of these characters.

In addition, "parasitic" lines, such as those indicated at 11 in Fig. 2, appear on the side or even inside the characters.

Since each elementary motif is formed by an electrode which must be electrically isolated from the neighboring electrodes, it is necessary to connect each motif to the electronic control system by means of a separate electrical connection.

These connections are formed by tracks which, like the electrodes, are formed by a photolithographic process on a substrate covered with a conductive layer and are therefore capable of modifying the optical characteristics of the liquid crystal located between them and part of the counter electrode. It is therefore understandable that these connections can appear on the cell at the same time as the alphanumeric characters displayed, which further contributes to a deterioration in the quality of the display.

To remedy this, it was proposed to install each connection in height

he of its overlap with the counter electrode into several very fine branches 11a, such that they become invisible (Fig. 2a), or to provide an extremely complicated counter electrode that only masks the electrode, but not the electrical connections.

In both cases, the result is devices that are complicated to manufacture and, of course, expensive.

Furthermore, the devices according to this application EP 0 180 685, although providing a significant improvement in terms of the appearance of the characters, are still very limited since they do not allow the display of lowercase letters. They also have the significant disadvantage of having to be dimensioned according to the size of the figures and letters to be displayed. This dimension is therefore mandatory and can only be modified by replacing the device already installed with another of a different size.

Accordingly, the present invention aims to remedy these drawbacks by providing an improved display device capable of displaying many more stylized characters, for example the Helvetica semi-bold font with excellent definition (aesthetics), free from defects of the type mentioned above, but which makes it possible to minimize the number of pixels in order to obtain only a slightly increased price.

The present invention also aims to provide a display device that addresses the problem of letter dimensions at the lowest possible cost.

Accordingly, the invention relates to an electronic display device of the type comprising:

- at least one electro-optical display means,

- Elementary motifs associated with electro-optical display means, which elementary motifs are formed for the most part from a series of alphanumeric stylized and selected characters in the form of a composite mosaic structure, the grid of which is formed by the said motifs, which have heterogeneous and complementary contours, arranged concordantly so as to be in-

to fit together in a manner similar to a puzzle, which elementary motifs form rows and columns delimiting zones of characteristic writing for the display of letters or digits, characterized in that the elementary motifs in the writing zones are formed in separate groups in which these motifs are arranged one below the other at the limit of contact and are separated by a distance provided to ensure the electrical isolation of these motifs from one another, each group of motifs being separated from the adjacent group or groups by optically passive spacer bands having a width which is significantly greater than the distance.

The invention will be better understood by reading the detailed description below taken in conjunction with the accompanying drawings, which are given by way of example only, and in which:

- Figure 1 shows schematically and in cross-section a liquid crystal cell of a conventional type which is, for example, the active display means of the device according to the invention,

- Figure 2 is one of the alphanumeric characters displayed by a known device, which figure illustrates the disadvantages of this type of character,

- Fig. 2a is a greatly enlarged view of the arrangement of elementary motifs at the level of defect 10 of Fig. 2,

- Figure 3 is a plan view of a mosaic according to a first embodiment intended to equip a display device according to the invention, the patterns of this mosaic being formed in this example by electrodes of a cell such as those shown in Figure 3.

1 is reproduced,

- Fig. 3a is an enlarged view of the area IHa of Fig. 3,

- Fig. 3b is a view similar to Fig. 3, but showing different elementary motifs of the mosaic in connection with their electrical connection.

&bull; *

- Figures 4a to 4k each show certain alphanumeric characters that can be displayed by means of the mosaic according to the first embodiment, and

- Figure 5 is a plan view of a counter electrode according to the invention,

- Figure 6 is a plan view of a mosaic according to a second embodiment of the invention,

- Fig. 7 is a plan view of a basic grid intended to form a mosaic as shown in Figs. 3 and 6 and corresponding to the first step of the manufacture of this mosaic,

- Fig. 8 is a plan view of a second manufacturing step of the mosaic comprising the basic grid of Fig. 7 in combination with an additional grid,

- Figure 9 shows a third step in the manufacture of the mosaic of Figure 6, in which the blackened areas correspond to continuous separations or cut-outs arranged on the mosaic in order to hatch it,

- Fig. 10 shows the grid obtained after the step shown in Fig. 9, and

- Figures 11 to 38 represent alphanumeric characters which can be displayed in particular thanks to the mosaic of Figure 6.

Referring first to Fig. 1, there is shown a liquid crystal cell constituting the active display means of the device according to the invention, which cell 1 comprises, in a known manner, a transparent front plate 2 and a transparent rear plate 3 connected to one another by a sealing frame 4. The sealing frame 4 delimits a sealed volume in which a mixture 5 composed of a liquid crystal and, for example, dichroic colorants is enclosed. The front and rear plates 2 and 3, which form the substrate, carry on their inner surfaces electrodes 6a and a counter electrode 6b, the latter, which are transparent, being formed, for example, from a mixture of indium oxide and tin oxide. The front and rear plates 2 and 3, respectively, in the same way generally carry a dielectric layer and an outer layer.

alignment layer, which are not shown here.

Moreover, the electrodes 6a and the counter electrode 6b comprise electrical connections which, like the latter, are structured by a photolithographic process on the blades 2 and 3, which electrical connections, not shown here, are connected to an electronic control circuit, not shown. Moreover, in this example, the cell 1 additionally comprises an element 7 of the reflector-diffuser or transflector type, depending on the display mode desired.

The operation of such a cell is currently widely known. It is easy to specify here that when a potential difference is applied between the electrodes 6a and the counter electrode 6b, the portion of the liquid crystal located between this electrode and this counter electrode changes its structure, so that this portion of the display cell changes its optical characteristics, creating a difference in luminosity between active and non-active portions, which creates optically contrasting zones.

As explained above, devices currently available on the market comprise electrodes 6a which are cut out and shaped to be able to display signs of relative aesthetics.

However, and as shown very schematically in Fig. 2, certain alphanumeric characters displayed by these devices have defects marked with 10.
These defects materialize in the form of dots or marks at the level of which the cell does not seem to be active, with the displayed sign having the appearance of being "gnawed".

It is therefore apparent that this type of disadvantage has a particularly detrimental effect on the commercial attractiveness of the device, given that this type of device is intended to enable the display (of destinations, for example) in public spaces such as train stations or airports.

This type of defect creates the illusion of premature wear and tear and gives many users the impression of poor quality.

In addition, one generally recognizes relatively fine lines on the sides or inside of displayed characters, which are visible when one approaches the display device, which lines correspond to the electrical connections designated 11 in Fig. 2a.

To avoid the appearance of such lines, one technique consists in cutting a counter electrode 6b in a special way so that no part of this counter electrode is located opposite an electrical connection 11. However, since each elementary pattern has its own electrical connection consisting of the free space left on the substrate between this pattern and the adjacent pattern, it is easy to see that the design of the counter electrode 6b becomes correspondingly more complicated and that the latter is consequently all the more expensive.

As shown in Fig. 2a, another solution consists in dividing each terminal 11 into several branches 11a, which branches are finer and consequently much less visible, at least from a certain distance.

Here too, it can be seen that the production of these branches by photolithography considerably complicates the manufacture of the display means and does not allow for a reduction in cell costs.

Figures 3 and 6 show a plan view of the two embodiments of the mosaic according to the invention, the patterns of this mosaic, generally referred to as "pixels", being in this case formed by electrodes 6a. Similarly, these patterns can be formed by electroluminescent diodes arranged on a suitable support or by any other display means that can be excited electrically.

The formation of the pixel elementary motifs according to the invention corresponds very well to the definition of mosaic and in particular of composite mosaic, since it is observed that these motifs have heterogeneous and complementary contours, namely rounded, straight or oblique, with indifferent combinations, which motifs are arranged in concordance to fit together in a similar way to a puzzle. It is observed that all these motifs are in an irregular and disordered form

- 10 -

without any systematic repetition of the rows or columns in one direction or the other.

The elementary motifs m^ to m of the mosaics of Fig. 3 and 6 respectively (not all of which are provided with reference symbols) are adapted to one another and associated with one another in such a way that the device according to the invention can display a whole range of alphanumeric characters, such as the letters of the Latin alphabet in upper and lower case, certain letters used in European languages such as Germanic or Nordic, as well as the digits 0 to 9, all of these characters being able to be provided with their associated accentuation, including underlining. Advantageously, each mosaic of these two embodiments is designed to reproduce the characters approximately in the "Helvetica Semibold" font.

Furthermore, the mosaic M of elementary motifs m allows
the display of all punctuation marks so that the combination of several mosaics M with each other, adjacent or superimposed in modules, enables the display of intelligible messages, formed in the form of structured sentences or in the form of groups of coded words.

It can be seen that thanks to a hatching of this mosaic (a process that will be explained later) certain elementary motifs m,
are grouped together in groups G. to G, which elementary motifs in each group are connected in such a way that they are very close to each other, on the limit of contact, leaving a small distance Y between them.

The motif groups G^_ are arranged in rows L1 to L6 and in columns C1 to C5. The isolated elementary motifs m,, m ₂ and nu enable the accentuation of Germanic and Nordic characters. The elementary motifs m ₁ and m^ are aligned and are provided in the extension of columns C1 and C5 respectively. The elementary motif nu, which has the appearance of a roughly rectangular ring, is arranged clearly below the elementary motifs m ₁ and m ₃ and opposite the central column C3.

The rows L1 to L6 of the groups G. to G delimit at least three characteristic zones A, B and C respectively, with a final zone D forming the above-mentioned accentuations.

t ·

&bull; * I

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Zone A is the zone of visualization or materialization of a first size of majuscules, while zone B is the zone of visualization of minuscules. Zone C, for its part, is the zone which makes it possible in particular to indicate the end of feet as well as to indicate underlines, zones A, B and C each comprising five appropriately aligned columns.

Zones A and B advantageously comprise, in the first embodiment of Fig. 3, five and three lines of characteristic groups, respectively, which selection of odd numbers of lines enables the display of letters or numbers such as "B", "3" or "8", the recessed parts 20 of which are centered with respect to a horizontal transverse line 22, as is particularly shown in Figs. 4g to 4j.

Furthermore, the fact that there is an odd number of lines in zone A for uppercase letters and lines in zone B for lowercase letters allows the display of uppercase and lowercase letters which are substantially centered, as shown in Figures 4b, 4d, 4f and 4g to 4k. This particular characteristic of the arrangement of the groups G^ to _Gn relative to one another thus allows the visualization of balanced characters of an aesthetic aspect which is entirely satisfactory.

Moreover, in each separate and characteristic group G _1- the distance Y separating each elementary motif (for example the motif m^) from the neighboring motif or motifs, in this case the motifs &tgr;&eegr;,- to m ₇ , is small, ie in the

fr fi

Order of magnitude from 10.10 m (10 pm) to 50.10 m (50 um). This distance has the essential function of electrically isolating the neighboring motifs and forms the width of the insulating gaps Es on the mosaic that separate the motifs from each other. The motifs in each group are therefore arranged very close to each other and appear to be connected even at a small distance. As can be observed in the letters and numbers of Fig. 4a to 4k, this distance Y does not appear in the characters displayed.

One can define any group G as being formed by at least two elementary motifs, united adjacent to each other and separated from each other.

which is separated, at least partially, by an isolation distance Es.

Preferably, the spacing distance Y is chosen to be as small as possible, taking into account the manufacturing conditions and the selected efficiency.

In the preferred embodiment of the invention, illustrated in Fig. 3, each motif group comprises at least in the zones A and B a spacing interval of rectilinear form.

Furthermore, each characteristic group G 1 to 6 is separated from the adjacent group or groups by spacer bands b _1-n , each spacer band being in fact formed, in the case of a liquid crystal cell, by the absence of the conductive layer on the substrate between the electrodes 6a and the adjacent groups. This substrate is formed by the lamella 2.

The spacer bands b, to b preferably all have the same width X ₅ which width is preferably in the order of magnitude of

3 "3

1.2.10 m (1.2 mm). Typically it is chosen to be 1.5.10 m (1.5 mm).

It can be seen that the value X, i.e. the width of the spacing bands separating the various characteristic groups G. to G, is overall significantly larger than the value Y, which is the width of the intervals or isolation spaces Es left between the neighbouring elementary motifs in the same group. In the present case, the value X is chosen to be between 25 and 125 times the value Y.

It has been estimated that the value R, which defines the ratio between the value of X and the value of Y (R=X/Y), gives satisfactory results when R is at least greater than 15, in other words when the width of the spacing bands is 15 times greater than the distance Y left between the motifs.

Preferably, the value R is chosen equal to 30 or X =

1.5.1O ^-3 m (1.5 mm) and Y = 50.10~ ⁶ m (50 μηη). For this purpose, it should be specified that preferably the distance Y is less than 100.10
m (100 ym) is selected.

In general, in the embodiment of Fig. 3

and 6, the mosaic according to the invention has a hatched structure such that the separating bands provided between two adjacent groups always have a width X greater than the spacing distance Y left between the motifs of these groups.

Furthermore, in this embodiment, all elementary motifs, whether in zone A or in zone B, are organized in groups, namely connected in pairs, at least partially at the limit of contact. In the present case, the mosaic comprises 152 elementary motifs, of which only five are isolated, and it can be seen that in the entire mosaic about 97% of the elementary motifs are organized in groups.

This choice of group-wise organization obviously has important functional consequences, but it also gives the mosaic M, i.e. the display device, the possibility of displaying characters of a very particular style, such as those shown in Fig. 4a to 4k. The spacer bands b1 to b2 form optically passive areas and form, between the groups G1 to G2, preferred passages for electrical connection elements 30 from the elementary motifs m3 towards the periphery of the display means, as shown in Fig. 3b.

These separation bands b, _{j_n} form clearly defined free zones, as appears very clearly in Fig. 3, so that it is quite easy to form the counter electrode 6b shown in Fig. 5 in a corresponding shape, which counter electrode 6b is adapted so that its "cut-out" zones 40 are arranged, corresponding to the absence of the conductive path, opposite the separation bands in which the electrical connections are made. In this way, it is understood that these areas are optically passive and that the electrical connections 30 do not appear on the display device during the visualization of alphanumeric characters.

In addition, the mosaic M, namely the formation of the various elementary motifs m, among each other, is provided in such a way that at most four separating bands b^_ _n intersect each other on or in the active display means. The separating bands b^_ , at least at the level of their intersecting point I (Fig. 3a), are angularly offset from each other by

an angle °t- greater than 60°.

The value of this angle <*- corresponds to that from which the appearance of defects, as defined below, begins to decrease significantly.

Preferably, the angle OC is equal to a maximum of 90°. It should also be specified that in the preferred embodiment, the external contour of each group of motifs G- is substantially rectilinear, which contour is preferably substantially rectangular.

The separation bands b. are in fact formed by continuous or cut-out separations S^ to S _n formed on the larger part of the display means, which continuous separations S ₁ to S traverse the mosaic M from beginning to end to end at its right and left lateral edges and its upper and lower edges respectively. This is particularly true in zones A, B and C for the vertical separations S 1 to S 2 and in zones A and B for the horizontal separations S ₅ to S 6 .

Be that as it may, throughout the mosaic the separation bands b^ to b _n and the continuous or cut-out separations S ₁ to S _n are organized vertically or parallel relative to the reading direction L of the characters on the mosaic.

If one starts from a reading direction which is straight and horizontal, it can be specified that the continuous or cut-out separations S ₁ to S ₇ and the separation bands which they form can be defined as being in directions which are respectively substantially vertical and horizontal.

The display device according to the invention makes it possible in particular to eliminate errors such as the dots or marks 10 that appear in the characters displayed by currently known devices. Reference is made here to Fig. 2a, which represents in detail the design of elementary patterns of a known display device.

The appearance of defects 10 in such a design can be explained by the combination of several phenomena.

First, at a small distance relative to the

* t

· 4

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pointing device, the defects are geometrically represented as an arc or a circle of radius R1, which circle is tangent to the ends or points of various elementary motifs converging towards the intersection point i_ . In the present case, it is observed that the radius R1 is already greater than the spacing distance a_ left between the various elementary motifs. In this way, even at a short distance, the defect 10 already appears dominant over intervals left between the motifs, which defect, moreover, appears in these intervals in the same optical mode, different from that of the characters displayed, that is to say in a way that contrasts with these characters.

With a greater distance, the phenomenon of optical "erosion" occurs at the ends or convergence points of the various elementary motifs, i.e. a loss of definition, whereby the eye has the tendency to no longer distinguish these points, but to recognize rounded edges f_.

In this way, the defect 10 grows considerably at this distance, to materialize in the form of a circle with radius R2, which radius R2 is much larger than radius R1 of the defect, which is visible at a short distance.

In this way, the distance between the interval a_ and the radius R of the defect 10 increases with increasing distance, so that the defect 10 becomes very predominant compared to the interval a_ mentioned previously.

In the mosaic configuration according to the invention, it is observed, as shown in Fig. 3a, that over a short distance the enveloping circle of the intersection point I at the level of the separation bands, for example b13, b18, b19 and b20, has a radius r of a value which is smaller than the width X of the separation bands b, _{3 18} pn·

In this way, the enveloping circle does not appear at short distances and does not form a defect, since it does not predominate over the width of the separation bands b.

In addition, at large distances the optical "erosion"

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less large, since for an equal circular arc f_ this circular arc f_ has the tendency to approach clearly the points or extremities of the groups G,.

In this way, the enveloping circle of the intersection point I has a radius r ₂ with a value substantially equal to the width X of the separation bands b ₁ _ _n . Accordingly, virtually no defect appears in the displayed alphanumeric characters with such a configuration, whether at short or long distances.

Furthermore, it has been observed that the definition of the characters and the readability are improved when the separator bands b.
and in particular the continuous or cut-out separations S. to S , which form the hatching of the mosaic, are oriented parallel and/or perpendicular to the reading direction of the characters displayed, the mosaic M being oriented on a group of display panels in the direction in which it is shown in Fig. 3, namely vertically.

It has also been observed that this arrangement improves the aesthetics of the characters displayed.

It should be noted here that this mosaic M offers an aesthetically pleasing feature thanks to its configuration, in that the accentuation elements of the minuscules (see figures 4d to 4f) are arranged in zone A, where the visualization or materialization of the majuscules takes place. In this way, the accentuation elements of the minuscules are practically attached to these minuscules, as is the case in the various alphabets, such as the Latin alphabet. This possibility is again illustrated by the group-like arrangement of the elementary motifs. Since the attachment of additional elementary motifs within the same group is made possible thanks to the quasi-contiguous arrangement of elementary motifs in this group, the accentuation elements are indistinguishable in the corpus of an alphanumeric majuscule character that this group uses for its visualization, as shown by the characters in figures 4d to 4f.

Furthermore, it should also be specified that the separation bands b,
so that the continuous or cut-out separations S- to S

are arranged in such a way that their intersection points I are located outside regions of materialization of branches of the signs that appear vertically or horizontally.

Referring now to Fig. 6, there is shown a composite display mosaic according to a second embodiment of the invention.

The mosaic according to this embodiment comprises four continuous or cut-out vertical separations oriented perpendicularly to the reading direction L, as well as three continuous or cut-out separations S5 to S7 oriented parallel to the reading direction L, i.e. defined as extending horizontally. In this embodiment, the seven continuous or cut-out separations forming the hatching of the mosaic M have a width X of a value equal to that mentioned above.

Using Figures 7 to 10, we will now explain the process used to create the mosaic grids in Figures 3 and 6 and how the hatching of these mosaics was created with bands, i.e. with separation or optically passive cutouts.

Referring first to Fig. 7, there is shown a basic grid T ₁ , called the first grid, which forms the initial structure of the mosaic according to the invention. This basic grid T ₁ is intended to form the zone B which enables the display of lowercase letters as well as the display of a first set of small digits.

In a very advantageous manner and as can be seen in Fig. 8, this basic grid T^ has been partially reproduced, in particular its upper part, designated T ₂ , has been reproduced. The dot-dash line L _c represents the upper part of the basic grid T. which has been reproduced and then attached to the top of the basic grid T _1. It should be noted that the cutting line L for duplicating the basic grid has been positioned in such a way that, after joining the two grids T ₁ and T~, the oblique isolation spaces are in concordance, which ultimately makes it possible to display characters of different dimensions within the same mosaic.

&bull;t
· · *

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The purpose is the cutting line L in the interface of insulation

L»

It positions the spaces which are oriented at an angle.

After having obtained this duplicated structure of the basic grid, in particular after having obtained an additional grid, called the second grid T ₂ , arranged above the first, T ₁ , one proceeds to hatching the resulting grid T 1 by means of continuous or cut-out separations S 1 to S 2 , arranged in the orientation explained above. As can be seen in Fig. 9, the continuous or cut-out separations cover the entire resulting grid T ₃ , since they penetrate the greater part of the mosaic according to the invention and thus form different groups of elementary motifs in the mosaic. As can be seen in Fig. 9 and in comparison with Fig. 8, the separations or cut-outs S ₁ to S ₇ partially cover certain elementary motifs of the grid T ₃ . Moreover, these separations or optically passive cutouts are arranged in such a way as to cover and mask the elementary patterns of small areas which have been blackened in Fig. 9 for the purpose of better reproduction of the drawings. Since these separations in band or cutout form S 1 to S ₇ are optically passive and correspond to an absence of the electrode surface, the elementary patterns of small area are eliminated and do not need to be assigned to an addressing which poses problems both in terms of electronics and in terms of electrical connections.

Advantageously, the mosaic according to the invention comprises at least two separations or horizontal sections, designated S ₅ and S 6 , which are very advantageously arranged near zones in which the density of elementary motifs is the greatest. These zones are designated 100 and 120 respectively. Preferably, these separations or sections S ^ and S ₆ are located tangentially with respect to these zones 100 and 120 of high density of elementary motifs.

Accordingly, it becomes much easier to control the elementary motifs in pixel form, which are difficult to access and to which an electrical connection must be made. It will be seen that the two separations or horizontal cutouts S ₅ and S _g are on either side of a line

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of pixel groups L· intended to form a horizontal intermediate bar for the formation of lower case letters, as will be seen in the following figures. More precisely, these separations or cutouts S ₅ and S _g are arranged tangentially with respect to this line L. and this intermediate bar.

In addition, this mosaic accordingly comprises a third separation or horizontal section S ₃₅ arranged tangentially with respect to a line L ₃ forming the group of motifs intended in particular to indicate a higher horizontal bar of minuscules. Preferably, this separation or section S ₇ is arranged directly above the line L ₃ .

As regards the vertical division into bands or sections, it should be specified that at least two of them, namely the divisions S. and S, are positioned tangentially with respect to the areas or columns C ₁ and Cr of the mosaic intended to form, in particular, the feet of letters.

Preferably, the device according to the invention comprises four continuous or cut-out separations arranged perpendicular to the reading direction, which four separations or cut-outs delimit between one another the five columns Cj to Cr, of which columns Cj ₅ , C ₃ and C ₅ constitute lateral and central columns respectively for forming feet. It should be specified that this central column C ₃ and lateral columns C 1 , Cr have equal widths. Furthermore, the three columns C ₁ , C ₃ and C ₅ for forming feet are separated in pairs by intermediate columns C ₂ and C ₄ which are of equal width to one another but have a width smaller than that of the three columns C 1 , C ₃ and Cr.

Fig. 10 shows a hatched grid T», which is the result of the operation in Fig. 9 and to which the insulating spaces Es have been added in order to form accents, letter bases or to round off certain alphanumeric characters.

As can be seen more precisely in Fig. 6, the mosaic according to the invention comprises four display zones of alphanumeric characters of different

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rather size.

The mosaic according to the invention comprises a first display zone A which serves to form alphanumeric characters of medium size and in particular to form a first set of capital letters and digits (Figs. 11-18). This first zone A uses all the columns and rows of the mosaic except for the last row L ₅₉ which serves the zone C for forming the end of the feet of large letters and for forming underline bars.

This mosaic includes a second zone E intended to enable the display of alphanumeric characters of larger dimensions, namely capital letters and large digits. The letters displayed are visible in Figures 19 to 26.

It can be seen that zone E uses the entire available surface of the mosaic, and zone A is therefore contained in zone E.

The third characteristic display zone of this mosaic is zone B, which is intended essentially to enable the display of small digits in a first position, as explained below, and of lowercase letters. However, the lowercase letters use a part of zone A and a part of zone C for certain letter heads and footers, respectively. This zone B is therefore located in zone A and is arranged directly above the underline zone C.

The characters that can be displayed thanks to this zone B are shown in Figs. 27 to 34.

The mosaic according to the invention also comprises a fourth zone F which in turn enables small digits to be displayed, but which have a position that differs from that displayed by zone B, namely significantly higher up. Zone F is superimposed on the interior of zone B, which together and superimposedly form zone A. The characters that can be displayed by this zone F are shown in Figs. 35 to 38. It can thus be seen that this mosaic comprises at least two characteristic zones for the formation of characters of the same family (digits, uppercase or lowercase letters), but of different sizes. More precisely, it comprises at least two

characteristic zones A, B for the formation of digits of different sizes. In an even more precise manner, it comprises three characteristic zones A, B ₅ E for the formation of digits comprising three different sizes, namely large, medium and small.

Finally, it comprises a fourth characteristic zone F for the formation of digits, and in particular small digits, at different levels, an upper and a lower one. It will therefore be understood that a mosaic has been created in a very advantageous manner, capable of displaying, with one and the same grid, namely the final hatched grid T5 according to Fig. 6, different sizes of digits (small, medium and large) and different sizes of one and the same family of letters (large and small). In this way, it is possible to meet advantageously the problem of the predetermined size of alphanumeric characters, which possibility of changing the size with one and the same mosaic also makes it possible to eliminate a display cell in the case of, for example, the display of the time.

It turns out that this device and this method enable the realization of an extremely large number of motifs on one and the same mosaic, which makes it possible to stylize the characters without restrictions while maintaining an excellent definition without affecting the manufacturing costs of the device.

It should also be specified that the invention can relate to an electronic display device with a low degree of multiplexing, i.e. in which certain elementary patterns are electrically connected to one another according to the degree of multiplexing. In this case, the counter electrode B6 must comprise regions electrically isolated from one another, provided with their own electrical connections and no longer be in a monoblock (continuous) as is the case for the counter electrode shown in Fig. 5.

Claims (24)

EXPECTATIONS 1. Electronic display device of the type comprising: - at least one electro-optical display means (1), - elementary motifs (m, to m ) associated with the electro-optical display means (1), which elementary motifs (m, to m ) are formed for the most part from a series of alpha-numeric stylized and selected characters in the form of a composite mosaic structure, the grid of which is formed by said motifs having heterogeneous and complementary contours, arranged concordantly to fit together in a manner similar to a puzzle, which elementary motifs form rows (L1 to L6) and columns (C1 to C5) delimiting zones of characteristic writing (A, B) for the display of letters or digits, characterized in that the elementary motifs Cm ₁ to m _n ) are formed in the writing zones (A, B) in separate groups (G ₁ to G ) in which these motifs (m, to m ) are arranged one below the other at the limit of contact and are separated by a distance (Y) provided to ensure the electrical insulation of these motifs from one another, each group of motifs (G, to G) is separated from the adjacent group or groups by optically passive spacing bands (b, to b ) having a width (X) which is significantly greater than the spacing (Y). 2. Device according to claim 1, characterized in that the optically passive bands (b ₁ - b ) have a width (X) which is at least 15 times greater than the distance (Y). 3. Device according to claim 1 or 2, characterized in that the width (X) is typically 30 times greater than the distance (Y). 4. Device according to claim 3, characterized in that the distance (Y) is less than 100.10 m. 5. Device according to claim 4, characterized in that the distance (Y) is chosen to be equal to 50.10" ⁵ m. 2 - 6. Device according to one of claims 1 to 5, characterized in that the optically passive bands are formed and provided on the mosaic in positions such that these bands are able to cover and mask the elementary patterns of the smallest surface in order to eliminate them. 7. Device according to one of claims 1 to 6, characterized in that the bands are straight and are all positioned exclusively perpendicular or parallel to the reading direction of the characters on the device. 8. Device according to claim 7, characterized in that it comprises at least two separations which are tangential to regions of the mosaic intended in particular for the formation of letter bases. 9. Device according to claim 7 or 8, characterized in that it has four continuous separations which run perpendicular to the reading direction, which four separations delimit five columns called verticals, three of which represent lateral or central columns for forming the feet. 10. Device according to claim 9, characterized in that the three vertical columns for forming the feet have the same width. 11. Device according to claim 10, characterized in that the three columns for foot formation are separated in pairs by intermediate columns which have the same width as one another, but whose width is smaller than that of the three columns mentioned. 12. Device according to one of claims 7 to 11, characterized in that the separations extend over the entire mosaic and end at its upper and lower edges. 13. Device according to claim 7, characterized in that it has at least two separations called horizontals, which extend parallel to the reading direction of the characters. 14. Device according to claim 13, characterized in that the two horizontal separations are arranged near the zones in which the density of the elementary motifs is greatest. 15. Device according to claim 14, characterized in that the horizontal separations run tangentially with respect to the zones of high density. 16. Device according to claim 13, characterized in that the two separations are arranged on either side of a horizontal intermediate web intended for the formation of lower case letters and tangential to this web. 17. Device according to claim 16, characterized in that it comprises a third separation which is tangential to an upper horizontal lower case letter web, immediately above the latter. 18. Device according to one of the preceding claims, characterized in that the mosaic is capable of displaying different character sizes for a family of letters and/or digits. 19. Device according to claim 18, characterized in that the mosaic comprises at least two characteristic zones (A,E;A,B,E) for the formation of characters of one and the same family, but in different sizes. 20. Device according to claim 18 or 19, characterized in that the mosaic comprises at least two characteristic zones (A, B) for the formation of digits of different sizes. 21. Device according to claim 20, characterized in that the mosaic comprises three characteristic zones (A ₅ B, E) for the formation of digits of three different sizes. 22. Device according to claim 18, characterized in that the mosaic comprises a characteristic display zone (F) for the formation of digits at an upper or lower level in the device. 23. Device according to claim 18, characterized in that the mosaic comprises at least one basic grid, referred to as the first grid, which is partially duplicated to form display zones of characters of different sizes. 24. Device according to claim 23, characterized in that the first grid is partially duplicated in an additional grid referred to as a second grid, which second grid is arranged above the first.