FR2950980A1 - PROCESS FOR OBTAINING A CATADIOPTRIC PANEL - Google Patents

Abstract

Device for printing a relief on a plate element, characterized in that the device comprises a non-planar printing surface and at least a part of this surface comprises a relief complementary to a retro-reflective relief.

Description

The present invention is in the field of reflective plates for supporting information. Said reflective plate may include panels for road signs, highway and urban, but also signs or advertising signs, decorative plates, ... In this area, a major problem is the visualization of these panels in the dark or by lack of ambient or natural light (night, thunderstorm, ...) Different types of solutions are known according to the needs, in particular the plates 10 may be illuminated by an activated light device in case of insufficient brightness. Alternatively, these plates are coated with reflective materials, referred to as "retroreflective materials", whose function is to make them visible at night in the light of an external source such as headlights of vehicles. These retroreflective coatings generally give satisfaction in terms of visualization in low ambient or natural light, but the operations required for their placement on support panels considerably increase the cost price of the reflective panels. In addition, in order to produce reflective panels of different size, a large stock of reflective coatings having different characteristics of color and brightness is required, which poses problems related to the management of a large stock of raw material. as well as increased complexity related to adhesion problems of the coating on a support surface. Reflex reflectors are also known which are reflective pieces whose principle is to return the light towards the source, or thanks to a specifically arranged reflective surface having microprisms known as "retro-reflectors".

With reference to FIG. 1, the operating principle of a retro-reflector is the arrangement of reflecting surfaces 10 and 12 at right angles. Thus, when a radius 2a is sent to a retro-reflector, the perpendicularity of the mirrors allows the compensation of the successive reflection angles so as to return, in the end, a radius 2b parallel to the incident ray 2a with a negligible shift. This principle, called the "principle of total reflection", works regardless of the angle of the incident ray (see rays 3a and 3b). A reflex reflector therefore sends light back to the source that sent the incident ray, regardless of its location.

The principle presented in Figure 1, can be quite generalized in 3 dimensions using three reflective surfaces parallel in pairs and having for intersection a cube-shaped vertex. Thus a plate having a reflective surface with a catadioptric relief composed of a multitude of reflex reflectors makes it possible to return almost all of an incident ray towards its source (i.e. car headlights). This technical effect is very useful for the problem of viewing said plates in the dark or more generally for lack of ambient or natural light. For the manufacture of such plates and with reference to FIG. 2, it is known to use a mold 2 allowing a material 24 intended for molding a plate element, to confer, after hardening, a catadioptric relief 25 on a of these surfaces. However, the manufacturing by molding reflex reflectors is expensive because it requires very precise molds making them expensive and complex to manufacture and prepare. As a result, beyond a certain plate size, manufacturing by molding is inconceivable because generating excessive resources and costs, or even for formats beyond a certain size, molds that do not exist on the market and almost impossible to manufacture. As an illustration, a mold for the manufacture of plate element with a dimension of 200 mm by 200 mm can reach 150,000 C.

In addition, the molding is an operation requiring significant waiting times (especially for the solidification of the plate element), which increases the production time. For these reasons, the use of retro-reflectors has so far been limited to small areas and only in the fields of cycles and automobiles, and more recently on road markings. Reflex reflectors are sometimes made in the form of small parts that are arranged on larger support parts by different means, which leads to additional installation costs and increased complexity. The present invention aims in particular to provide a plate element manufacturing method having a surface having a catadioptric relief and having a lower cost compared to the state of the art. It is another object of the present invention to provide a plate member manufacturing method and apparatus having a surface having catadioptric relief in a continuous manner, thereby reducing production times. For this purpose, the invention relates to a device for printing a relief on a plate element, characterized in that the device comprises a non-planar printing surface and that at least a part of this surface comprises a relief complementary to a catadioptric relief. Advantageously but optionally, the invention comprises at least one of the following features: the surface is cylindrical; the complementary relief comprises a complementary pattern with three planar surfaces arranged at their intersection with a projecting vertex in which said surfaces planes are two to two perpendicular, the pattern being evenly distributed on the complementary relief, - the patterns of the complementary relief are distributed so that all the vertices are equidistant, - the device has a cylinder shape having a diameter of from 150 mm to 250 mm and preferably from about 200 mm.

Of course these numerical values are given for illustrative purposes only and do not constitute a limitation of the present invention. In particular, it should be noted that the catadioptric principle remains valid by homothety.

The invention also relates to an assembly for printing a plate element, characterized in that it comprises a printing device according to the invention, and a support element for supporting said plate element between the support member between the printing device.

Advantageously but optionally, the support element comprises a plane. Advantageously but optionally, the support element comprises a cylinder.

The invention also relates to a method of manufacturing a plate member having a surface having a catadioptric relief, the method comprising the following steps: - providing a plate member for receiving a catadioptric relief on its surface, - printing a catadioptric relief at the surface of the plate member by means of a printing device according to the invention, so as to unroll the printing surface on the surface of the plate member. Advantageously but optionally, the method comprises the following step beforehand: - heating the plate element.

Other characteristics, objects and advantages of the present invention will appear on reading the detailed description which follows, with reference to the appended figures, given by way of non-limiting examples and in which: FIG. 1 is a representation schematic of a 2-dimensional catadioptric relief; FIG. 2 is a diagrammatic representation of a mold for molding a retro-reflective relief according to the state of the art; FIG. 3 is a representation of a device for printing a catadioptric relief on a plate element according to a possible embodiment of the present invention, - Figure 4 is a representation of a device for printing a catadioptric relief on a plate element according to a FIG. 5 is a representation of the catadioptric pattern obtained by the printing method according to the invention seen from above according to one embodiment of the present invention. Possible embodiment of the present invention, - Figure 6 is a view of the pattern of Figure 5 in section VI-VI, - Figure 7 is a view of the pattern of Figure 5 in section VII-VII, - Figure 8 is a diagrammatic representation of a plate obtained according to a process of the present invention; FIG. 9 is a diagrammatic representation of a plate obtained according to a process of the present invention; FIG. 10 is a graph showing a process of FIG. printing according to a possible embodiment of the present invention.

The present invention is particularly advantageous in that it provides a property of light reflection towards the source by avoiding the use of a retroreflective coating sheet arranged on a panel. The present invention also relates to a method and a device for producing a reflective plate made of plastic material, in which shapes are made in relief on one side of the plate, intended to give it a reflective surface state. With reference to FIG. 3, a device according to the invention is intended for printing a catadioptric relief on a plate element. According to a preferred embodiment of the present invention, the device is made in the form of a cylinder 3 comprising a non-planar printing surface (cylindrical), at least a part of this surface comprising a complementary relief 31 to a catadioptric relief. This cylinder may be hollow or full; a solid cylinder providing the advantage of having an additional mass for exerting a force necessary for printing the catadioptric relief on the plate element 4 resting on a printing medium 40. The printing medium 40 can be produced on the shape of a support plane and is part of a printing assembly further comprising an element 39 for holding the cylinder 3, the cylinder obviously retaining a freedom of rotation about its main axis. With reference to FIG. 4, the support 40 may advantageously be made in the form of a support cylinder 40 arranged parallel to the printing cylinder 3, the plate element 4 flowing between the two cylinders during printing. catadioptric relief. The support cylinder 40 exerts a support force F2 on the plate element 4 and rotates in the direction R2, in the opposite direction to the direction of rotation R of the cylinder 3. Thus, continuous manufacture of plate elements can be envisaged for a similar to rolling.

Preferably, but not limited to, the cylinder-shaped device has a length L of about 650 mm and a diameter D ranging from 150 mm to 250 mm and preferably about 200 mm. However, the cylinder may be of a larger size for example having a diameter of about 300mm.

Advantageously, this cylinder is made of treated steel and the complementary relief 31 of copper or treated steel and / or chromed. Such materials or their equivalents in terms of mechanical property are known from the state of the art and will not be more detailed.

This printing cylinder allows, by means of a rotation of the latter on a plate element 4, to print a catadioptric relief on its surface.

The cylinder 3 exerts a force F on the plate element 4. This force F (using the support force F2) is due in part to its mass (hence the importance of the choices of materials and the fact that the cylinder is full) and can, on the other hand, be assisted by additional means (not shown) of the printing assembly which would exert pressure in the direction of the force F to increase the contact force at the point 37 between the impression cylinder 3 and the plate element 4, this force being sufficiently large so that the complementary relief 31 of the cylinder 3 can print a catadioptric relief 41 on the plate element 4. Advantageously, the plate element is in methacrylate.

It should be noted that in order to obtain an optimal impression of the catadioptric relief, the plate element is in a slightly viscous state (softening of the material), a state controlled by temperature. Preferably, the temperature must be controlled to a value slightly greater than the glass transition temperature (Tg), that is to say the temperature at which a Young's modulus drop is observed. The glass transition temperature is a function of the material used; for example: Tg PMMA (polymethyl methacrylate) = 105-115 ° C., Tg PC (polycarbonate) = 150 ° C., Tg PS (polystyrene) = 90-100 ° C.

Thus, in order to optimize the impression of the catadioptric relief, the plate element is heated prior to the printing of the relief, in particular using any means for controlling the temperature of the plate element known to the state of the art and able to maintain the temperature of the plate member at a temperature slightly higher than the glass transition temperature.

The advantage of using a cylinder instead of, for example, of a printing device in the form of a plate is to be able to use this cylinder for plate elements having variable widths and especially a length not limited by the printing device. Indeed, the use of a printing device in the form of a plate for example limits the dimensions of the plate element to be printed. In addition, to make a flat-shaped printing device of large size requires a manufacturing cost of this device, for the same reasons as the manufacture of a mold as described above. Thus the manufacture of the plate elements by a printing cylinder can be carried out continuously.

Referring to Figure 5, we will see more precisely the constitution of the relief obtained by printing the complementary relief 31 of the surface 30 of the printing cylinder 3 according to a possible embodiment of the present invention. Figure 5 is a projected representation of the relief obtained by printing the complementary relief 31 of the cylinder seen from above.

The complementary catadioptric relief advantageously comprises a pattern distributed evenly over the relief 31. This pattern is complementary to three surfaces 310a, 310b and 310c arranged so that each of the surfaces are perpendicular to one another at the level of the edges. 313 to 313b and 313c and so that at their intersection is a vertex at right angle (a cubic-type top 312) projecting (that is to say protuberant), vertex in which said planar surfaces 20 are two at two perpendiculars. By right angle, "perpendicular", or any equivalent term, any angle will be understood to mean a value essentially of 90 °, a fluctuation of this angle being possible, although this angle must be between 85 ° and 95 °.

As indicated above, the pattern described is distributed evenly over the complementary relief 31; this distribution is such that all the vertices 312 of the relief obtained are all equidistant from each other, this distance E being able to go from a length of 5 to 6 mm from each other and preferably from approximately 5.8 mm. The three flat surfaces as described previously of the catadioptric relief obtained, is integrated within a hexagonal structure H, this hexagonal structure allowing a mosaic construction of the repetition of said pattern Referring to Figure 6 which represents a projection according to the VI-VI section of a portion of the relief obtained by printing the pattern, it should be noted that the angle 3120 formed by the stop 313a relative to a vertical project 3124 of the cubic sum 312 is preferably about 55 °. The vertex 318a of one end of the hexagon H is such that it has between the vertical projectile 319a and the stop 317a an angle 3180 of about 35 °; the height of vertical projection 319a between the top 312a (or the top 318a) and the intersection A of the edges 317a and 313a being preferably about 1.6 mm. Consequently the horizontal projections of the edges 317a and 313a (that is to say, the projections comprising the point of intersection A of the edges 317a and 313a) are respectively 1.1 mm and 2.2 mm long.

The set of values are valid for all the cuts resulting from a rotation of the VI-VI section by an angle of + 120 ° or -20 °.

Referring to Figure 7, which shows a projection according to section VII-VII of a portion of the relief obtained by printing the pattern, the flat surface 310c has relative to the vertical projected angle 3121 of about 35 °. The top 318e of one end of the hexagon H is such that it has between the vertical projectile 319a and the 317th stop an angle 3180 of about 35 °; the height of the vertical projected 319a between the top 312a (or the top 318a) and the point of intersection E of the edges 317c and the face 310c being preferably about 2.4mm. Accordingly, the horizontal projections of the face 310c and 317c (i.e., the projections comprising the intersection point E of the edges 317c and the face 310c) are both 1.7 mm in length.

The set of values are valid for all the sections resulting from a rotation of the VII-VII section by an angle of + 120 ° or ± 120 °.

Thus, it is easy to design a catadioptric relief from this relief, such that the impression of the complementary relief allows to obtain a catadioptric relief. The catadioptric relief previously described is given as an illustration and may be of a different size, being recalled that the catadioptric principle remains valid by homothety.

With reference to FIG. 10, using the pattern of the complementary relief, it is possible to implement a method of manufacturing a plate element having a surface having a catadioptric relief, the method comprising the following steps: heating a plate member for receiving (i.e., printing) a catadioptric relief on its surface; the material of the plate element to be chosen so as to be able to print a catadioptric relief on its surface while guaranteeing a certain strength of this catadioptric relief, in particular through the time at step 101, - to supply the heated plate element - step 102, - print this catadioptric relief on the surface of the plate element with the aid of the printing device according to the invention, so as to unroll the printing surface on the surface of the plate element such as as shown in FIG. 4 - step 103.

The term "unwind" means that the printing cylinder rolls on the plate so as to print on said plate a catadioptric relief with the complementary relief 31; accordingly, the relative velocity between the printing cylinder 25 and the plate at the point of contact, i.e. at the printing area, is zero. However from the point of view of the terrestrial reference, the part in longitudinal movement can be either the plate, the cylinder, or both.

Referring to Fig. 8 showing the profile of a plate member 4 whose surface 87 has been printed with a printing device, the plate member 4 comprises a body 80 supporting said surface 87 The plate element is preferably made of methacrylate material and may be transparent and optionally tinted in the mass. Subsequent to the implementation of a catadioptric relief on the surface 87 of the plate member 4, it may be expected to coat the surface 87 with a thin layer 88 of reflective paint or varnish. The fineness of this layer must be sufficient to maintain the intrinsic light reflection properties due to the catadioptric relief of the surface of the plate element resulting from the transformation, in order to ensure the necessary levels of reflection and to correspond to the fields of reflection. color defined in the standards relating to road signs. Subsequently, it is possible to cover the surface 86 of the plate element 4 (intended to receive light emissions from the outside) of a colored, transparent or opaque film 89 which supports the decoration necessary for the presentation of the information. the required signaling (eg traffic or road safety information). Thus, as shown in FIG. 8, a light beam 90 arriving on the surface 86 of the plate element 4 is reflected towards its source thanks to the repeated catadioptric pattern of the relief printed on the surface 87, once having through layer 89 and body 80 of the plate member.

With reference to FIG. 9, the completed panel may be installed like any signboard on an element such as a post 11. For this purpose, it is provided at the end of the embodiment of the arrangement on the plate element 4 of fixing means 92, these fixing means are known from the state of the art and will not be more detailed. In addition, the arrangement of a bottom element 93 is advantageously provided for reinforcing the solidity of the plate element 4 as well as serving as a sealing and sealing element (especially at the level of the means). 92) to protect the integrity of the catadioptric relief 87. Moreover, such a bottom may advantageously have a white color on its surface 933 in the direction of the plate element 4, in order to improve the visibility of the element. plate in full brightness (ie in daylight).

It is understood that the embodiments which have just been described are not limiting in nature and that they can receive any desirable modifications without departing from the scope of the present invention. In particular, the numerical values previously described are given by way of example and are not intended to limit the scope of the present invention. The set of numerical values mentioned above are given by way of example and do not constitute a limitation of the present invention.

Claims (11)

REVENDICATIONS1. Device for printing a relief on a plate element (4), characterized in that the device (3) comprises a non-planar printing surface (30) and that at least a part of this surface comprises a relief (31) complementary to a catadioptric relief. 2. Device according to claim 1, wherein the surface (30) is cylindrical. 3. Device according to claim 1 or 2, wherein the complementary relief (31) comprises a complementary pattern with three planar surfaces (310a, 310b and 310c) arranged having at their intersection a salient apex (312) in which said planar surfaces (310a, 310b and 310c) are two to two perpendicular, the pattern being evenly distributed on the complementary relief (31). 4. Device according to claim 1 to 3, wherein the patterns of the complementary relief (31) are distributed so that all the vertices (312) are equidistant. 5. Device according to one of claims 1 to 4, which has a cylinder shape having a diameter ranging from 150 mm to 250 mm and preferably about 200 mm. 25 6. Assembly for the printing of a plate element (4), characterized in that it comprises a printing device (3) according to one of claims 1 to 5, and a support element ( 40) for supporting said plate member (4) between the support member (40) between the printing device (3). 30 7. Printing assembly according to the preceding claim, wherein the support member (40) comprises a plan.20 The printing assembly of claim 6, wherein the support member (40) comprises a cylinder. 9. Print assembly according to claim according to one of claims 6 to 8, characterized in that it comprises means for controlling the temperature of the plate member adapted to maintain the temperature of the plate member. at a temperature slightly above the glass transition temperature. A method of manufacturing a plate member (4) having a surface having a catadioptric relief (31), the method comprising the steps of: - providing (102) a plate member (4) for receiving a catadioptric relief (31) on its surface, - printing (103) a catadioptric relief (31) on the surface of the plate element (4) by means of a printing device according to one of claims 1 to 6 , so as to unroll the printing surface (30) on the surface (87) of the plate member (4). 11. The manufacturing method according to the preceding claim, which comprises previously the following step: - Heat (101) the plate member (4) at a temperature slightly above the glass transition temperature. 20