WO2008062247A1

WO2008062247A1 - Display device

Info

Publication number: WO2008062247A1
Application number: PCT/IB2006/003122
Authority: WO
Inventors: Emin Gabrielyan
Original assignee: Emin Gabrielyan
Priority date: 2006-10-27
Filing date: 2006-10-27
Publication date: 2008-05-29

Abstract

The present invention relates to a display device comprising at least two superposed layers. On each layer chosen images are printed. The upper layer is made by a transparent material allowing to achieve optical effects.

Description

DI SPLAY DEVICE

The present invention relates to a display device comprising at least two superposed layers . The present invention is based on the moire effect and may be used in watch industry .

The present invention is related to creation of superposition images or related to creation of special effects thanks to the superposition of several layers .

For example , we can have a layer printed on a transparent material which is superposed on top of a layer printed on a paper . The superposition of these layers creates a visual effect or an optical image . Mechanical movements or rotations of the layers produce modifications of the optical effect . So it is possible to produce a text or pictograms as a result of superposition of two layers . The shapes of images , text or pictograms are embedded in the base layer ( e . g . printed on a paper ) by means of numerous duplications of the deformated versions of the basic shape reduced in si ze . T'hanks to the corresponding matching revealer layer the superposition of two layers make appear an optical effect representing the desired shape . The optical image , achieved due to superposition of layers can be a magni fied version of the shapes embedded in the base layer The movement or rotations of the layers can produce , movements , rotations and deformations of the optical image resulting from the superposition of the layers

The invention will now described in relation to watch dial s .

Design of a moire watch

I. Table of contents

Design of a moire watch 1

I. Table of contents 1

II. Abstract and Introduction 1

III. Superposition of two patterns consisting of periodic straight lines 2

IV. Constructing the contour of a spiral 4

A. A quick draft 4

B. Accurate approximation of a spiral - choosing checkpoints and computing corner points 5

C. Using arcs of a constant radius to connect the corner points 8

D. Using adapted radiuse for smoothing each corner point 8

V. Constructing spiral shapes relying on two spiral contours 9

A. Single spiral shape 9

B. Multiple spiral shapes 11

VI. Moire effects achieved by rotations of spiral based patterns 12

A. Decreasing circles 12

B. Quickly rotating radial ray 13

C. Slowly rotating radial ray 14

VII. Moire effect tuned to 12 hours scale of a watch 15

VIII. Moire watches with dial plates 17

IX. Conclusion and future works 19

X. Links 20

A. Moire watch 20

B. Multi-stripe line moire 20

XI. List of figures 20

XII. Legal 21

II. Abstract and Introduction

We present a design and the development details of a moire watch. The moire watch operates by a slow rotation of a revealer superposed on top of a base layer. The revealer is a pattern which has several spirals printed on a transparent surface (e.g. transparency). The base layer is a similar pattern printed on an opaque surface (e.g. paper). The slow rotation of the revealer corresponds to the rotation of the hour arrow on the watch. The moire effect corresponds to the rotation of the minute arrow of the watch. The moire minute arrow rotates 12 times faster than the revealer representing the hour arrow. The animated image of Figure 1 demonstrates such a watch.

This document presents the design of the spiral with equations for properly computing the related parameters. For all presented examples we provide links to postscript files. All implementation algorithms can be found in postscript files (in text format).

For animated images we provide also multi page PDF files. PDF files typically provide better quality. For viewing the animation through a PDF file, download the file and open it in a full screen mode (press Ctrl-L for full screen mode and Esc to return). Once in the full screen mode you can animate the image by scrolling up and down (using the arrow keys). The dimensions (size and timing) of an animated GIF file are often provided in a text or in a LOG file.

For static images we provide EPS files (Encapsulated Postscript). The EPS files can be included as an image into an MS Word document or can be used by many other applications.

III. Superposition of two patterns consisting of periodic straight lines

First, let us observe moire effect when superposing two layers consisting of periodic parallel lines. Figure 2, Figure 3 and Figure 4 show superposition of the revealer consisting of periodic parallel lines on top of the base layer with a similar pattern. The animation of Figure 2 demonstrates the moire effect obtained due to a rotation of the revealer. Figure 3 demonstrates horizontal movement of a slightly rotated revealer and Figure 4 demonstrates the moire effect achieved due to vertical movement of the rotated revealer.

For an implementation of the moire watch we use a moirέ effect similar to one shown in Figure 4. In a watch model, the revealer proceeds a circular movement and the white moire stripes (representing an arrow of the watch) have radial orientation and proceeds a faster circular movement. In order to meet these objectives we must rely on patterns having a form of spiral. In order to quickly evaluate different variations of pattern parameters we design a lightweight postscript method for constructing a spiral.

IV. Constructing the contour of a spiral

Postscript does not provide a direct functionality for constructing a spiral. Bitmap solutions are not scalable and additionally slow down the development evaluation cycles. We show that accurate spirals can be constructed relying on arcs. Arcs must be connected so as their tangent lines perfectly match at the connection point. The radiuses of the arcs must be also chosen properly.

A. A quick draft

A quick draft approximating a spiral is shown in Figure 5. Refer to the postscript file [gs] for more information on implementation of this algorithm.

B. Accurate approximation of a spiral - choosing checkpoints and computing corner points

An accurate implementation relies on checkpoints (lying on the spiral) interleaved by a constant delta angle. For each pair of checkpoints we find the intermediate corner points. The corner points do not lay on the spiral, they represent (approximately) the intersection of the two tangent lines of the spiral passing through the two adjacent checkpoints respectively.

Figure 6 shows the checkpoints of a spiral (in red) and the corner points (in green and blue).

The black dot in the figure represents the center of the spiral. The coordinates of the red checkpoints are computed according the equations (1) and (2):

X_n = (r + dr • ή) • cos(a + da • ri) (1) and y_n = (r + dr - ή) - sin(α + da - ή) (2)

In equations (1) and (2), x_n and y_n represent the coordinates of the n-th check point, r is the initial radius of the spiral, dr is the increment of the radius per each da increment of the angle, and a is the initial angle of the spiral.

Parameters of the spiral shown in Figure 6 are given by the following equations: dr = 50

Λr -15 r = 50 a = 0

Each red point of Figure 6 is surrounded by two corner points, a small blue and a larger green. For each red point of the spiral, the blue point represents the previous corner point and the green point represents the next corner point. The next (green) corner point of a given (red) checkpoint of the spiral matches with the previous corner point (blue) of the successive (red) checkpoint of the spiral. This matching is demonstrated by the figure.

The coordinates of the previous corner point of check point n are computed as follows:

an

The coordinates of the next comer point of check point n are computed as follows:

and

As we said before about the matching of the checkpoint's next corner point with the successive checkpoint's previous corner point: next _ prev Xn ~ ^Xn+l (8) and next _ prev Jn .> B+1 (9)

The spiral (red) check points are almost (but not exactly) lying on the line connecting its previous and next corner points. Figure 7 shows an image, where the adjacent corner points of a spiral are connected with straight lines.

The parameters of the spiral shown in Figure 7 are defined by the following equations: dr = 50 da = 30

(10) r = 50 α = 0

C. Using arcs of a constant radius to connect the corner points

The image of Figure 7 can be improved if we use arcs for connecting the two straight lines at the corner points. This improvement is shown in Figure 8. Here we use identical arcs at all corner points.

The parameters of the spiral are the same shown in equation (10). The radiuses of arcs, smoothing the corner points of the figure are all equal to 50 points.

D. Using adapted radiuse for smoothing each corner point

When we adapt the radiuses of the arcs for each corner, the spiral appears smooth and continuous (see Figure 1).

F

The smoothing arc radius arcr£^rev at the previous corner point of the n-th checkpoint is computed according the equation (11).

arcr_n ^prev = (r + dr - n)~ — (11)

V. Constructing spiral shapes relying on two spiral contours

A. Single spiral shape

In order to build spiral shapes we must rely on two contours. In Figure 10 we show a shape relying on two contours with identical parameters, except that one of the contours is turned by 15 degree. The full contouring shape can be drawn properly if one of the spiral contours is constructed in the counterclockwise direction and the other one in the opposite clockwise direction. See the postscript file £gs] for the implementation details (on how to construct the spiral path in the reverse order).

In Figure 10 we can visually notice the inaccuracies of the interpolating curves in respect to the red checkpoints. It is sufficient to increase the number of check points to eliminate the inaccuracies and improve the interpolation image (see Figure 11).

In Figure 10 and Figure 11 the difference between the two contouring spirals of the shape is that the inner spiral contours is rotated by 15 degree. We can combine the rotation with expansion (i.e. a shift in the radius). The spiral shape of Figure 12 is constructed by two contours, where the inner one is rotated by 5 degree and the outer contour is additionally expanded by 10 points (i.e. the initial value of the radius of the outer contour is 10 point farther than that of the inner contour). See the postscript file [ΓJS] for more details.

B. Multiple spiral shapes

For producing moire effect we draw multiple spiral shapes in the base layer and revealer layer. In a layer pattern the shapes are all identical and differ only by their angle. Concerning the individual shapes, the inner and the outer contours start at the same angle (no relative rotation between the contours of a single shape) and the contours differ only by the initial radius (defining thus the radial thickness of the shape). Figure 13 shows several spiral shapes, respectively rotated. The checkpoints of the contours are marked by red dots.

VI. Moire effects achieved by rotations of spiral based patterns

A. Decreasing circles

The animated image of Figure 14 shows superposition of two patterns based on multiple spirals. The spirals of the base layer are red. The revealer is black. Each layer has 15 spiral shapes. The radial width of all spiral shapes is 10 points. The delta radial gain per one full rotation of the spiral shapes is equal to 190 points for the base layer spirals and to 180 for the revealer spirals. Check the postscript file for other details [ΓJS].

B. Quickly rotating radial ray

In Figure 15 the base layer (in red) has 29 spiral shapes and the revealer (in black) has 30 spiral shapes. A moire effect produces a white radial ray from the center toward the edge of the circle. One rotation of the revealer causes 30 rotations of tile ray. The radial width of shapes (both in the base layer and revealer) is 5.5 points. The delta radial gain per full rotation is 190 for the

( 29 revealer spirals. For base layer spirals the delta radial gain per full rotation is 184 « 190

The spirals of Figure 15 are quite thin and a side moire effect can be produced with the screen of the computer during the animation of the image.

C. Slowly rotating radial ray

Figure 16 shows an animation with turning black revealer. The base layer (in dark brown) consists of 12 spirals and the revealer consists of 13 spirals. The radial width of the spiral shapes of the revealer is 6.5 points and 6 for the brown spiral shapes of the base layer. The delta radial gain per full rotation is 100 and 92.3 for the revealer and the base layer spirals respectively.

A full rotation of the revealer causes 13 rotations of the moire white radial ray.

VII. Moire effect tuned to 12 hours scale of a watch

The animated images of Figure 17 and Figure 18 show moire watches, where the white ray makes 12 complete turns as the revealer layer makes one complete turn. In both figures the revealer contains 12 equally interleaved spiral shapes (in black) and the base layer contains 11 spiral shapes

(in dark brown). The delta radial gain per complete turn is 200 points for the revealer and 200 — for the base layer (in both figures). The only difference between the two figures is that the radial width of the spiral shapes (of the revealer and the base layer) is 14 points in Figure 17 and is 15 in Figure 18. Therefore the opening in Figure 17 is wider than the opening in Figure 18 which results in a less scattered and more directed ray in Figure 18.

VIII. Moire watches with dial plates

Figure 19 and Figure 20 show animations of moire watches with dial plates. Figure 19 contains a dial plate only for minutes (labeled at 15m, 30m, 45m and 60m). Figure 20 contains a dial plate for minutes (labeled at 5m, 20m, 35m and 50m) and a dial plate for hours (labeled from Ih to 12h). In both figures the radial width is 14.5 points for the spirals of the base layer and of the revealer.

IX. Conclusion and future works

Watchmakers are using mechanical mechanisms for properly accelerated movements of the minutes' and seconds' arrows relatively to the movement of the hours' arrow. In a watch, the mechanically maintained movements of the arrows serve uniquely to visual purposes.

The acceleration of movements obtained with moire is nothing more than a visual effect. Moire acceleration cannot be useful for any mechanical purpose. Since the accelerated movements of watch minutes' and seconds' arrows are dedicated only for visual perception, we can rely on moire acceleration for implementation of these arrows.

Figure 20 demonstrates that a moire effect can replace the mechanical minute arrow of a watch. There is a space for improvements concerning the opening angle of the minute arrow ray and the visibility of smaller and denser labels of the minute dial plate. Moire implementation of the faster moving arrow for seconds should be also attempted (possibly with some compromises).

The functional moire watches may be of interest in the watch making industry, both from the production cost perspective and from the new design approach perspective. Actually, new design features should be of a special interest since the Swiss watch making industry is currently experiencing a noticeable progress. For example during the second quarter of 2006, Bulgari recorded a turnover of 243.9 million euros, an increase of 16.3%. The Swatch Group, the world's leading watch manufacturer, increased its turnover by 13.1% to 2,347 million francs in the first half of 2006 (http://www.fhs.ch/).

X. Links

A. Moire watch o Formats of this document [htm], [doc], [pdf], [zip] o The address of this web site, http://4z.com/people/emm-gabrielyan/folders/060915-moire- watch/ o Initial experiments related to moire watch, http://4z.com/people/emin- gabrielvan/folders/060912-moire- watch/

B. Multi-stripe line moire o Multi-stripe line moire achieving rotated text images (random short and long stripe periods are used), http://4z.com/people/emin-gabrielvan/folders/060911 -multi-stripe-moire/ o Multi-stripe line moire magnifying horizontal text images (short and long stripe periods), httpyMz.com/people/emin-gabrielyan/folders/OάOgOS-moire-rand-freq/ o Multi-stripe line moire magnifying a simple pictogram (short stripe periods), http://4z.eom/people/emin-gabrielyan/folders/060821-moire-rand-j5:eq/

XI. List of figures

Figure 1. Moire watch [pdf], [ps], [gif], [txt] 2

Figure 2. Rotation of the revealer, two periodic patterns of parallel lines [pdfj, [ps], [gifj, [log] 3

Figure 3. Horizontal movement of the revealer, two periodic patterns of parallel lines [pdf], [ps], [gif] 3

Figure 4. Vertical movement of the revealer, two periodic patterns of parallel lines [pdf], [ps], [gif] 4

Figure 5. A quick approximation of spiral [pdf], [ps], [eps], [doc] 5

Figure 6. Checkpoints and the corner points of the spiral [pdf], [ps], [eps], [doc] 6

Figure 7. Connecting the corner points of a spiral by straight lines [pdf], [ps], [eps], [doc] 7

Figure 8. Using arcs for connecting the corner points [pdfj, [ps], [eps], [doc] 8

Figure 9. Adapting radiuses of the arcs of each corner point [pdfj, [ps], [eps], [doc] 9

Figure 10. Constructing a spiral shape relying on two spiral contours 10

Figure 11. Interpolation of the spiral shape with an increased number of checkpoints [pdfj, [ps], [eps], [doc] 10

Figure 12. The two spiral contours of the spiral shape differ by the rotation angle and the starting radius [pdf], [ps], [eps], [doc] 11

Figure 13. Multiple spiral shapes, respectively rotated [pdfj, [ps], [eps], [doc] 12 Figure 14. Superposition of two spirals resulting into decreasing white moire circles due to rotation of the revealer [pdfj, [ps], [gifj 13

Figure 15. Quickly rotating white radial angular ray [pdfj, [ps], [gifj, [log] 14

Figure 16. Slowly rotating radial moire ray [pdf], [ps], [gif], [txt] 15

Figure 17. Moire watch with 12 hours, a wide angle ray [pdf], [ps], [gifj 16

Figure 18. Moire watch with 12 hours, a narrow angle ray [pdfj, [ps], [gif], [txt] 17

Figure 19. Moirέ watch with the minute dial plate (30 frames) 18

Figure 20. Moire watch with the minute and hour dial plate (360 frames) 19

Moire e-samples

Table of content

Moire e-samples • Section I. Table of content Section II. Brief description Section III. Images

Subsection III.A. Granularity of a mono-ring solution Subsection III.B. The background base layers of the mono-ring and multi-ring solutions

Subsection III.C. Text moire examples Subsection III.D. Animated mono-ring samples Subsection III.E. Simultaneous implementation of the minutes' and seconds' clock-hands

Subsection III.F. Complications with multi-ring patterns Section IV. Links Section V.

Section VI. !/θ!U

Section VII. Vo i b Section VIII. Table of figures.

Brief description

Thanks to our invention, we can achieve a visual acceleration of any slow mechanical rotation. We only need to have a slowly rotating transparent disk and a possibility to print images on that disk. The shapes of figures printed on the disk are computed according to our equations. The visual effect of an accelerated movement depends on the form of the opaque shapes printed on the rotating disk. For example the fast movement of the minutes' (or seconds') clock-hand can be obtained by using only the mechanical movement of the hours' clock-hand. For this purpose a transparent disk can be attached to the axis of the hours' clock-hand. The slow rotation of the disk will produce a visual effect of an accelerated rotation. The hours and the minutes can be simultaneously displayed using only single slow mechanical movement.

We can obtain seconds and tens of seconds from the mechanical rotation of the minutes' clock hand. Similarly, for example for a chronometer, 1/100 fractions of seconds can be obtained by using the mechanical rotation of the seconds' clock hand.

No electronic components are used in this technology. For production, only a possibility of printing on a transparent surface is required (e.g. metallization on a sapphire or on quartz).

Section Hf. Images

The animated images of this section demonstrate the visual effect of the virtual acceleration. In all animations there is a background static layer and there is a foreground rotating transparent layer.

In the examples of this section, we assume that the transparent layer is connected to the axis of the hours' clock-hand. The slow rotation of the transparent layer produces the fast rotations. The hour's clock-hand is printed on the same transparent layer so we can see simultaneously also the slow mechanical rotation.

There are 19 animated images in this section with a total size of about 180 Megabytes. Please wait until all images are completely downloaded. Before viewing make sure that all images are downloaded.

Subsection HLA. Granularity of a mono-ring solution

Figure shows the simple "mono-ring" structure consisting of thick spirals. The spirals can be implemented in metal, without supporting sapphire. The spirals can be kept together thanks to two or more metallic rings. Such a solution without use of sapphire or of any other transparent material can be interesting for design of high end luxury watches.

The granularity of the spirals can be refined as shown in Figure2£lmplementation in metal without support becomes harder when the granularity is extremely fine. Our equations permit to refine the granularity until infinity, such that individual spirals are not visible and the labels appear as if through a semi transparent material.

Subsection HLB. The background base layers of the mono- ring and multi-ring solutions

The background immobile layer contains an image which is computed correspondingly to the shapes printed on the foreground transparent layer. Figure3 shows the image of the background layer for a mono-ring coarse-grained solution shown in Figure &t »

Multi-ring solutions of Figure^ 'and Figure ^f cannot be implemented in metal without a transparent support (such as sapphire).

Subsection ill. C. Text moire examples

Figures of this section show moire effect producing letters and texts. Rotation of the transparent disk produces an accelerated rotation of series of periodic text fragments. It is possible to achieve several simultaneous movements at different speeds and directions with a single mechanical rotation of the transparent disk.

Subsection III.D. Animated mono-ring samples

Subsection ULE. Simultaneous implementation of the minutes' and seconds' clock-hands

The transparent foreground revealer layer rotates at the speed of the hours' clock- hand. The slow mechanical rotation produces two speeds. One corresponds to the minutes' clock-hand speed and the second one corresponds to the seconds' clock-hand speed.

Complications with multi-ring patterns

Figure ^{H τ}. Smooth arrow shaped, fine-grained, scaled, light colors fedfl, [ES], [gifl

Section IV. Links

Experiments with simple patterns: http://4z.com/People/emin-gabrielvan/folders/060912- moire-watch/

Constructing spirals, mono-ring samples: http://4z.com/People/emin- gabrielyan/folders/060915-moire-watch/

Multi-ring samples: http://4z.com/People/emm-gabrielvan/folders/060918-moire- multistripe-watch/

Yellow watch sample: http://4z.com/People/emin-gabrielvan/folders/060919-vellow- moire-watch/

Samples for BNB concept: http ://4z. com/P eople/emin-gabriel v,an/folders/060927 - bnbconcept-samples/

Samples for Alec Avedisyan: http://4z.com/People/emin-gabrielyan/folders/061004- watch-alec-avedisyan/

Records related to contacts with watch makers: http://4z.com/People/emin- gabrielvan/folders/061 OOS-watchmakers-contacts/

Smooth bell shaped moire watches: http://4z.com/People/emin- gabrielyan/folders/061016-moire-watches-bell-shaped/

E-samples for De Bethune: http://4z.com/People/emin-gabrielvan/folders/061016- debethune-esamples/

Section VIlI. Table of figures

Figure 2.1 Coarse grained thick spirals [pdf], [ps], [png] base layer [pdfj, [ps], revealer [pdf], [ps] :

Figure22-Fine grained spirals [pdf], [ps], [png]

Figured Background base layer of a mono-ring solution [pdfj, [ps], [png] base layer [pdf], [ps], revealer [pdf], [ps] :

Figure ^ The visual result (superposition of the transparent layer on top of the background) of a complex multi-ring solution [pdfj, [ps], [png] base layer [pdf], [ps], revealer tpdfj, [ps] .'_

Figure 2-^Background base layer of a complex multi-ring solution shown in Figure 4 [pdfj, [ps], [png] base layer [pdfj, [ps], revealer [pdfj, [ps]

Figure ^C χ_ext moire example , , "PA" rotates in one direction and "PH" rotates in opposite direction [pdfj, [ps], jjpg], base layer [pdfj, [ps], revealer [pdf], [ps] ^'

Figure ²^ Text moirέ example . ,, "PATEK" rotates several times faster than the mechanical rotation of the foreground transparent revealer layer [pdfj, [ps], [jpg], base layer [pdfj, [ps] revealer [pdfj, [ps]

Figured Text moirέ example , "CAR" rotates in one direction and "TIER" rotates in opposite direction [pdfj, [ps], [jpg], base layer [pdfj, [ps] revealer [pdf], [ps] ...^" Figure ^ 3 Text moire example , "CA" rotates in one direction and "RT" rotates in opposite direction [pdf], [ps], Qpg] base layer [pdf], [ps], revealer [pdf], [ps]

Figure SO I Text moire example , "TAG" rotates in one direction and "HE" rotates in opposite direction [pdf], [ps], [jpg] base layer [pdf], [ps], revealer [pdf], [ps] ^'

Figure 31 . Coarse-grained mono-ring solution with a dark revealer, completely metallic implementation without a transparent support is possible [pdf], [ps], [gif]

Figure 32. Same as in Figure^! , but using light colors [pdf], [ps], [gif]

Figure ?3. Fine-grained mono-ring solution using dark colors [pdf], [ps], [gif]

Figure ty. Same as in Figure 35_* but using light colors [pdf], [ps], [gif]

Figure t&i Simultaneous implementation of the minutes' clock hand and the seconds' clock hand, the dots on the periphery represent the true mechanical movement [pdf], [ps], [gif]

Figure 36. One mechanical rotation (represented by the speed of the 12 dots on the periphery of the circle) produces two fast rotations, where the first internal moire rotation corresponds to the speed of the minutes' clock-hand and the second moire rotation makes one turn every 5 minutes. The labels represent the minutes [pdf], [ps], [gif]

Figure ^f , Simultaneous implementation of the minutes' and seconds' clock-hands, where the minutes' clock hand acceleration is achieved by using complicated multi-ring solutions. The labels behind the fast acceleration represent the seconds. One turn of the fast moire corresponds to 150 seconds [pdf], [ps], [gif]

Figure DO Same as in Figure %t, but with light colors; the rotating disk contains a clock-hand for hours. The movement of this clock hand represents the true mechanical movement of the disk. The small 12 squares on the periphery also represent the true mechanical rotation. The inner accelerated moirέ represents the minutes and the outer faster moire represents the seconds [pdf], [ps], [gif]

Figure ~>3ι Sharp bell-shaped, dark colors [pdf], [ps], [gif]

Figure^. Sharp bell shaped, black colors [pdf], [ps], [gif] 1 ^~

Figure M j. Sharp bell shaped, light colors [pdf], [ps], [gif]

Figured Straight shape, black colors [pdfj, [ps], [gif]

Figure l\\ Straight shape, light colors [pdf], [ps], [gif]

Figure Ij-tyj. Smooth bell shaped, black color [pdf], [ps], [gif] ^~

Figure^-SΪ. Smooth arrow shaped, black color [pdf], [ps], [gif]

Figure U^. Smooth arrow shaped, light color [pdf], [ps], [gif]

Figure kϊ Smooth arrow shaped, fine-grained, scaled, light colors [pdf], [ps], [gif]

Claims

1. Display device comprising at least two superposed, layers, characterised in that on each layer chosen images are printed, in that the upper layer is made by a transparent material allowing to achieve optical effects.

2. Display device according to claim 1, characterised in that it comprises at least three superposed layers and in that the upper layers are made by a transparent material.

3. Display device according to one of claims 1 or

2, characterised in that one or more of the layers is designed to move in different direction or to rotate .

4. Display device according to one of claims 1 to

3, characterised in that the achieved optical effects are geometrical figures or single or a multiple symbols or texts, or numbers.

5. Display device according to one of claims 1 to

4, characterised in that the achieved optical effects are movement at faster speed than the real mechanical movement or magnification of symbols or deformations of the images at different speeds.

6. Display device according to one of claims 1 to 5, characterised in that it is a watch dial.

7. Display device according to claim 6, characterised in that the images printed on the various layers are designed to fully or partially display time.

8. Display device according to claim 1, characterised in that it is designed to move the different layers in synchronism with the watch mechanism.