Background of the Invention It is known in the art to produce patterns or images with special light effects, so as for example by reflection of light from matt surfaces, from glossy surfaces or from objects within a transparent material when light passes through it or by passage of light through a system of transparent layers and optical layers, when the resultant pattern or image is formed which pattern or image depends on the illumination intensity or on the view angle.

In case of the glass plates used to decorate buildings, the decor of such plates is brought about by printing or by spraying ink on such plate, witch ink is then fired to obtain a permanent sun resistant colour decor. Also, it is known to provide the plates with a printed colour decor made of an inorganic material with subsequent tempering, whereby, a decor exhibiting intensive decorative effect is obtained, which decor is abrasion resistant, yields fast colour and is suitable to decorate both the interior and the exterior.

Also, it is known to decorate glass plates by printing with ink on glass, which, ink is then fired and then by sticking glass fragments on the decorated surface and the resultant system is then sintered and annealed to yield a rough surface which surface is then coated with a binder which a binder, which binder is then left to set.

Also, it is known to insert melted metal pattern elements between two endless bands of glass, which bands are formed by rolling.

In case of forming images by means of a system of layers, such layers are appropriately grouped and connected by suitable binders or adhesives.

Another method of producing decor consists in forming glass between rollers, which glass was previously softened by melting, whereby, one of the rollers is provided with convex or concave patterns, which patterns are transferred onto the surface of glass, and the glass is then cooled. Thereby, plates suitable for decoration of kitchens, bathrooms or buildings are obtained.

Also, it is known to produce decors by connecting rasters of images and/or signs, for example of characters, which rasters are put on each other, whereby, the rasters are formed by films provided with systems of printed elements.

However, at a given configuration of the optical environment the above specified solutions do not allow to create exactly defined patterns simply, at an acceptable price, in the required quality and in a number of variations on at least partially transparent and hard materials, for example on glass.

Summary of the Invention The above mentioned drawbacks are removed by a method of producing decor on a glass wall or floor tile used to yield an image provided with special light effects according to the present invention which method consists in that on specified opposite surfaces of the front and the back sides of a glass plate a system of decorative elements of decreased transparency or opacity is produced, which system forms a decor in the shape of at least one segment composed of arranged transparent signs and slots on each side of the plate, whereby the decorative elements of at least the front side are formed by ink and/or by hot rolling glass and/or by grinding glass, whereupon, the used decoration ink is further treated in accordance with the kind of the decoration material to obtain specific mechanical properties, and finally, final formatting and calibrating of the plate is carried out.

According to one preferable embodiment of this invention the decor of the plate back side is produced by fixing a film provided with a system of printed decoration elements to the back side of the plate.

According to another preferable embodiment of the present invention the system of decorative elements of decreased transparency or opacity is determined by finding out light effect deviations of the basic design of the layout of said elements in comparison to the desired resultant light effect and by carrying out a correction of deviations by changing at least one of the characteristics of at least one segment on one of the plate sides, whereby, said characteristics comprise number, size and density of the transparent signs and slots, segment orientation and colour alternative.

Preferably, the decorative elements are produced by applying heat fireable ink, which ink is applied by printing, spraying, putting ink into sunken areas and by using a decal. Glass ink, ceramic ink, metal ink or enamel can be used as the fireable ink.

If the decorative elements are produced by rolling or grinding of the glass surface, it is preferable to fill the sunken areas with heat fireable ink.

According to another preferable embodiment of the method according to this invention, the decorative elements are produced by using non-heat-fireable inks, for example those based on resins, enamels, W-light hardenable inks or chemically crosslinkable inks.

Also, it is preferable to modify the used decorative ink further by firing or by drying or hardening it to obtain specific mechanical properties that are in accordance with the kind of the decorative material.

By the method according to the present invention exactly delimited patterns of a quality superior quality are produced Simply and cost effectively so that they are determined for broad scope of applications. If the fireable inks are used, glass plates exhibiting special mechanical characteristics are obtained, which properties are a prerequisite of their use as the wall or floor plates. According to the method of this invention, patterns and the colour designs can be produced quickly and simply in a number of variations.

Detailed Description of the Invention A glass planar transparent or slightly coloured plate having dimensions up to 4 m x 5 m and thickness 1 to 25 mm is used as the starting blank plate.

At first, it is determined what opposite surface areas of the front and back sides and in what way will use a decor to yield light effects. Such selected surface areas are then decorated according to the respective project by applying a system of decorative elements exhibiting decreased transparency or opacity, whereby, such elements are grouped so as to produce a decor in the form of at least one segment of the arranged, transparent signs and slots on each side of the plate. The slots can also be continuously interconnected with signs, whereby, the segment always has one prevailing orientation or, to put it differently, one direction of slots or signs.

Preferably, the appearance of the resultant light effect is checked and eventually the original design of decorative elements layout is modified to obtain the optimal effect.

It is carried out in such a way that the light effect differences of the basic design of a system of the decreased transparency or opaque decorative elements in comparison to the original project are determined and the respective corrections of differences are carried out by modifying at least one of the characteristics of at least one segment.

To make a correction, changes of individual segment (s) characteristics of only one side of the plate are tested one after the other. The respective characteristics are the slot size, their length or width, further then the angular position of the segment (s), change in orientation of the segment (s), then the number and density of slots in the segment (s) or the size and density of signs and then colour combinations. The corrections can be carried out in a laboratory by means of a film, glass, etc., or directly during a visual evaluation by adjusting the printing machine producing the decor, i. e. by turning the machine into such position when the light effects are produced. For example, if a greater difference in the number of similarly oriented slots in the segments of both plate sides are applied, the light effect is increased. Also, in case of a greater difference in angular position of the segments, the light effect is increased. By a mutual combination of both factors the optimal effect can be obtained. In case, smaller size of the transparent slots and signs is chosen, decomposition and diffusion of light plays a greater role.

After final design of the decor, the method for producing decorative elements on plate sides is determined. The elements can be produced by applying ink, by rolling or by grinding or by combinations of said methods or by means of applying a printed film.

It is possible to produce a decor by the same method on both sides of the plate or a different method on both sides. For example, ink is used on the front plate side and a printed film is applied on the rear plate side, so as it will be described in greater detail below.

If a high hardness, abrasive resistance and chemical stability are required, fireable inks are used to produce the decor. A cheaper production combined but with lower durability in use is obtained if non-fireable inks are used.

The ink can be applied by one of the following methods: A blank glass plate, is formatted to the desired dimensions, e. g. by cutting, grinding, etc., and the plate it is then provided with ink print by screen or rotary printing.

Instead of screen printing, flexography can be used, whereby, the ink is applied on the relief on the surface of a flexible roller and the ink is then transferred to the glass surface. It is necessary to take into account that because of roller flexibility the decorative signs may not be entirely precisely demarked.

The ink can be applied on the blank plate also by spraying using a mask or a masking layer to cause that the ink gets only to the predetermined places for the required decor.

The decorating ink can also be applied on a blank plate by injecting when an programmable injection printer is used to inject the ink on predetermined places to yield the required decor.

Making of decorative elements by ink is a substitution of expensive and for small-series production unsuitable colouring of glass. It is more variable, by providing ink print on both sides the tile becomes coloured. It is preferable to coat at least 30 % of the front side area of the tile with ink.

The ink can also be wiped into the blank plate. A system of decorative elements is ground or hot rolled into the areas of the plate sides (so as it will be specified in detail later).

Then, the whole area is coated with ink and wiped with a blade so that the ink remains only in the sunken areas, whereby, the required decor will be formed.

Finally the decorating ink can be transferred to the blank plate by means of a decal. The respective arrangement of segments is applied by transferable ink on a carrier substrate, e. g. a paper, by a screen printing method and the transferable ink is then transferred to the blank plate.

After forming decorative elements, it is proceeded in accordance with the used ink material. This material is either fired using the respective temperature and firing temperature course to obtain minimal or maximal material stress, i. e. the ink is hardened, or the decorative material is left to dry or it is hardened using a source of UV light, eventually, it is hardened chemically.

Also, the front side of the plate can be decorated by hot rolling. This method uses changes in optical boundary and surface transparency in hot rolling. The unrolled part of the plate maintains its original optical characteristics, which characteristics are identical with those of the transparent signs and slots. The rolled part yields optical characteristics that are modified according to the roughness and the depth of the recesses provided. More particularly, a blank plate is rolled at 500 to 800 °C by means of a pressing tool, which tool presses recesses into the glass surface. The recesses have depth 0.001 to 1.0 mm. A system of decorative elements is so formed.

Considering that after cooling the recesses exhibit different optical properties in comparrison to the non press treated surrounding area, the optical boundaries and interference can be used to some extent together with the back side decorated by some of the above mentioned methods of decoration by ink. To increase the colour effect, it can be preferable to fill the recesses obtained by pressing using the above mentioned method of putting ink into the recesses.

Further, it is possible to decorate the front side by grinding.

Again, recesses are formed in the respective part of the surface so as in the previous case. For the grinding, the standard methods of grinding can be used. To modify optical characteristics of the ground plate parts, it is possible to use the same method as in case of rolling.

The rear plate side can be decorated using substantially the same methods as in the case of the front plate side. In case there are no high demands on hardness, it is possible to use sticking a film on it, which film is provided with a printed system of decorative signs. When the above mentioned methods of the plate front side decoration are used to decorate the back side, or their combination, the respective thermal process can be integrated into one operation, whereby, it can be made more rapid and simple.

When both sides of the plate have been decorated, the final formatting and calibrating of the plate is carried out.

Industrial Use The present invention can be used to produce tiles provided with exact and special decor yielding many colour or image combinations by a rapid, easy, cheap and variable method.

Claims 1. A method of producing decor on a glass wall or floor tile used to yield an image provided with special light effects, characterised in that on specified opposite surfaces of the front and the back sides of a glass plate a system of decorative elements of decreased transparency or opacity is produced, which system forms a decor in the shape of at least one segment composed of arranged transparent signs and slots on each side of the plate, whereby the decorative elements of at least the front side are formed by ink and/or by hot rolling glass and/or by grinding glass, whereupon, the used decoration ink is further treated in accordance with the kind of the decoration material to obtain specific mechanical properties, and finally, final formatting and calibrating of the plate is carried out.

2. A method of Claim 1, characterised in that the decor of the plate back side is produced by fixing a film provided with a system of printed decoration elements to the back side of the plate.

3. A method of Claim 1 or Claim 2, characterised in that the system of decorative elements of decreased transparency or opacity is determined by finding out light effect deviations of the basic design of the layout of said elements in comparison to the desired resultant light effect and by carrying out a correction of deviations by changing at least one of the characteristics of at least one segment on one of the plate sides, whereby, said characteristics comprise number, size and density of the transparent signs and. slots, segment orientation and colour alternative.

4. A method of any of the foregoing Claims, characterised in that the decorative elements are produced by applying heat fireable ink, which ink is applied by printing, spraying, putting ink into sunken areas and by using a decal.

5. A method of any of the Claims 1 to 3, characterised in that the decorative elements are produced by filling the sunken areas, having been formed by rolling or grinding, with heat fireable ink.

6. A method of any of the Claims 1 to 3, characterised in that heat fireable ink is used, preferably glass ink, ceramics ink, metal ink or enamel.

7. A method of any of the Claims 1 to 5, characterised in that non-heat-fireable ink, preferably ink based on resins, enamels, W-light hardenable or chemically crosslinkable inks are used.

8. A method of any of the foregoing Claims, characterised in that the used decorative ink is subsequently modified by firing, drying or hardening.