WO2019048792A1

WO2019048792A1 - Method for making a colour screen for a motor vehicle lighting and/or signalling device

Info

Publication number: WO2019048792A1
Application number: PCT/FR2018/052185
Authority: WO
Inventors: Alain Buisson; Christophe LAFFETA
Original assignee: Automotive Lighting Rear Lamps France
Priority date: 2017-09-08
Filing date: 2018-09-06
Publication date: 2019-03-14
Also published as: PL3679292T3; EP3679292A1; EP3679292B1; FR3071031A1; FR3071031B1

Abstract

The invention relates to a method for making a colour screen for a motor vehicle lighting and/or signalling device. The method according to the invention comprises a step of compressing a first film (2) against a second film (10) having a greater surface area, such that the first film (2) perforates the second film (10) and thus makes a space (22) having the dimensions of the first film (2). The first and second films are made of plastic material and are of different colours. Subsequently, a step of positioning the first film (2) in the space (22) is carried out such that said space (22) is plugged and a colour screen (24A) made of plastic material according to the invention is formed.

Description

Method for producing a color screen for a lighting and / or signaling device for a motor vehicle

Technical field of the invention

[01] The present invention relates to a method of producing a plastic color screen comprising at least one film inserted in another film of different color. It relates more particularly to the manufacture of a color screen for a lighting and / or signaling device for a motor vehicle, lantern type or projector. State of the art

[02] The regulations in force require the use of lighting and signaling lights on motor vehicles: direction indicators or flashing lights, fog lamps, position lights, parking lights, reversing lights, hazard lights, daytime running lights ... The trend is to group these lights as much as possible in the same lighting device to reduce their size.

[03] The most common solution is to place at the front of the lighting device a single screen comprising areas of different colors more or less transparent. Each color is associated with a lighting or signaling function mentioned above. The lighting device then has a separate light source to illuminate each color area, which allows to use a single screen incorporating all the functions imposed by the regulations. The use of a single color screen significantly reduces the size of the lighting device compared to devices using multiple screens of different colors.

[04] Generally, the color screen is made from a transparent support on which films of different colors are superimposed. However, the transparent support and / or the superposition of the color films alters the optical properties of each film, in particular their color and their light transmission properties. In addition, the superposition of the films color on the transparent support increases the thickness of the screen, which can be problematic when you want to limit the size of the lighting device.

[05] According to another disadvantage, the color films are held on the transparent support by means of adhesives which alter the optical properties of the color films over time.

[06] The invention aims to provide an alternative to the production of a color screen for a lighting and / or signaling device for a motor vehicle. More specifically, the invention seeks to provide a method of producing a screen comprising zones of different colors, whose light transmission properties are preserved during the manufacture of the screen and over time.

Description of the invention

[07] For this, the present application proposes a method of producing a color screen for a lighting and / or signaling device for a motor vehicle, implementing the following steps:

a step of compressing a first film against a second film of greater surface area, so that the first film perforates the second film and thus makes a transition to the dimensions of the first film, the first and the second film being in plastic material and different colors; then

a step of positioning the first film in the passage so as to close off said passage.

[08] In other words, the first film is compressed against the second film in order to detach part of the second film and replace this part. The first film thus plays the role of a punch to perforate the second film, but unlike a conventional punching process, the punch played by the first film is left in the second film.

[09] The invention thus allows the realization of a color screen comprising two zones of different colors without using a support transparent as mentioned above. As a result, the optical properties of each film are preserved during the manufacture of the color screen and its thickness is limited to that of the thickest film.

[10] According to another advantage, the first film is forced into the second film so as to be maintained by the latter. No glue or chemical agent is therefore used to maintain the films, which preserves their light transmission properties over time.

[il] According to another advantage, the first and second films do not overlap. The insertion of the first film into the second film can thus be performed independently of their optical properties, offering a greater variety of use of color films.

[12] According to another embodiment, the first film and / or the second film is transparent or translucent. At least one film has a color associated with a lighting or signaling function mentioned above.

[13] According to another embodiment, the first film has a thickness of between 0.375 mm and 0.8 mm, preferably of the order of 0.5 mm. By the term "thickness" is meant here the distance separating the largest opposite faces of a film.

[14] According to another embodiment, the first film is thinner than the second film. In other words, the thickness of the first film is limited to the thickness of the second film. The thickness of the second film is greater than 0.4 mm, preferably equal to or greater than 0.5 mm. According to a preferred embodiment, the thickness of the second film is chosen so that the second film has sufficient rigidity to maintain its shape. As such, the first and / or second film may be previously manufactured by a thermoforming technique.

[15] According to an alternative embodiment, the first film is positioned in the second film so as to be flush with and / or be set back from a large face of the second film. Preferably, the first film is arranged so as to be flush with a larger face of the second film, so that at the level of said face, the color screen is smooth or substantially smooth. This embodiment advantageously makes it possible to subsequently cover said face with a more homogeneous deposition of material.

[16] According to another embodiment, the first film deforms less easily than the second film, under the same mechanical stress normally applied to their larger faces. In other words, the plasticity and / or elasticity of the first film is lower than that of the second film, to facilitate the insertion of the first film in the second film, while preserving the shape of the first film. According to another advantage, this embodiment allows a better mechanical maintenance of the first film in the second film.

[17] According to another embodiment, the first film has an area of between 1 mm ² and 20 mm ² , preferably of the order of 10 mm ² .

[18] According to another embodiment, the surface of the first film has a aspect ratio of between 1: 1 and 1: 20. The outline of the first film may thus delimit an oval, circular, rectangular, square, triangular or other shape. In other words, the first film can be of varied and diverse forms.

[19] According to another embodiment, the first film and / or the second film is at least partially curved. In other words, the first and / or second film are not planar and may include one or more inflection points at one of their large faces. Preferably, the first film and the second film have the same shape, or substantially the same or the same radii of curvature.

[20] According to another embodiment, the first film and / or the second film is composed of a stack of layers. The first and / or second film may comprise at least one metallized layer. Preferably, the metallized layer is of chrome appearance, and / or of blue color. According to an alternative embodiment, the metallized layer is sandwiched between two polymeric plastic layers, polymethyl methacrylate (PMMA) or polycarbonate (PC).

[21] According to another embodiment, the method described above is reproduced so as to produce a color film comprising several first films. In other words, the method according to the invention can be implemented several times so that the first film forms in the second film geometric patterns of different colors and shapes or identical.

[22] According to another embodiment, before or before the compression step described above, the second film is positioned against an upper face of a matrix, the upper face comprising at least one opening of complementary shape to the contour of the first film so as to receive the portion of the second film which is detached by the first film during the compression step. Advantageously, the portion of the second film detached by the first film, commonly called knockout, is thus expelled into the opening present at the upper face of the matrix during the compression step. It should be noted that the term "superior" is here used arbitrarily, so that it is not intended to limit a particular arrangement of the matrix with respect to the color screen. [23] According to another embodiment, prior to the compression step, the contour of the first film is cut so as to have a shape complementary to the opening of the matrix. According to a preferred embodiment, the value of the clearance between the first film and the opening of the matrix is between 0.01 and 0.1 mm, preferably zero. In other words, the first film is shaped before the compression step so that the contour of the first film and the contour of the opening of the matrix are substantially the same, preferably identical.

[24] According to another embodiment, the largest opposite faces of the first film are connected by at least one passage. Preferably, the passage or passages extend in a normal direction to the larger faces. According to a preferred embodiment, at least one passage is made using an auxiliary punch, the auxiliary punch is inserted into the first film prior to the compression step of the first film against the second film, and the punch auxiliary is removed from the first film after the step of positioning the first film in the second film. Thus, advantageously, the auxiliary punch can be used to move the first film during the method of producing the color screen according to the invention. According to another advantage, the auxiliary punch allows to provide a passage in the first film which can be filled by a third film according to a method described above.

[25] According to another embodiment, the auxiliary punch is mounted on a punch so that the auxiliary punch is projecting from a bearing face of the punch, and said bearing face is superimposed substantially or preferably perfectly to the first film when punched by the auxiliary punch. According to a preferred embodiment, the bearing face is of identical shape to the first film so that the first film is in contact with the entire bearing face during its punching by the auxiliary punch.

[26] The present invention also relates to a lighting and / or signaling device for a motor vehicle comprising a color screen made according to one of the methods described above.

Description of figures

[27] The characteristics of the invention mentioned above, as well as others, will emerge more clearly on reading the following description of the exemplary embodiments below, with reference to the appended drawings in which:

FIGS. 1 to 3 illustrate the steps of a first example of a method of producing a color screen according to the invention;

FIG. 4 illustrates a front view of a color screen obtained according to the method illustrated in FIGS. 1 to 3;

FIGS. 5 and 6 illustrate a step of shaping a first film prior to the process illustrated in FIGS. 1 to 3. FIGS. 7 to 11 illustrate the steps of a second example of a method of producing a color screen according to the invention;

FIG. 12 illustrates a front view of a color screen obtained according to the method illustrated in FIGS. 7 to 11;

FIGS. 13 and 16 illustrate a step of shaping a first film prior to the process illustrated in FIGS. 7 to 11.

Detailed description of the invention

[28] As a reminder, the invention proposes a method of producing a color screen for a lighting and / or signaling device for a motor vehicle, comprising zones of different colors, whose transmission properties of the light are preserved during screen making and over time.

[29] Figures 1 to 4 describe a first example of manufacture of a color screen according to the invention. As illustrated in Figure 1, a first step of the method consists in maintaining a first film 2 against a punch 4. More specifically, the first film 2 is held against a bearing face 6 of the punch by reversible holding means. For example, the holding means may designate a double-sided adhesive interposed between the punch 4 and the first film 2, or suction means opening on the bearing surface 6, suction-type. The first film

2 is configured to cover the entire bearing face 6 without exceeding it.

[30] The first film 2 is made of plastic, in particular polymethyl methacrylate (PMMA) or polycarbonate (PC). It can be colorless or colored, transparent or translucent. The first film 2 may also include inclusions or irregularities present intentionally inside and / or on the outside of the film, in order to modify the incidence of a light beam passing therethrough. For example, the first film 2 may comprise prisms of defined structure and angle, to meet the requirements of the regulations in the field, known to those skilled in the art. The first film 2 may be composed of a stack of layers. The stack of layers may comprise a metallized layer. The metallized layer can be covered on each side by an adhesive layer, itself covered on one side by a layer of ABS and, on the other hand by a layer of PMMA and a protective layer.

[31] The thickness of the first film, defined as the distance separating its largest faces 8, is between 0.375 mm and 0.5 mm. According to the present example, its thickness is 0.5 mm.

[32] According to another step of the method, a second film 10 is disposed on a matrix 12 so as to completely cover a cavity 14 opening on an upper face 16 of the matrix 12. The cavity 14 defines an opening 18 at the level of the upper face 16, whose contour is of complementary shape to the contour of the bearing face 6. More specifically, the contour of the opening 18 is slightly greater than the contour of the bearing face to allow the insertion of a portion of the punch 4 in the cavity 14. In other words, the value of the cutting clearance between the punch 4 and the die 12 is less than 0.5 mm, preferably this value tends to zero.

[33] The second film 10 is also made of plastic, in particular polymethyl methacrylate (PMMA) or polycarbonate (PC). It can be colorless or colored, transparent or translucent. The second film 10 may also include inclusions or irregularities intentionally present inside and / or on the outside of the film, in order to modify the incidence of a light beam passing therethrough. The thickness of the second film, defined as the distance separating its largest faces 9, may be equal to the first film 2. As illustrated in FIG. 1, the thickness of the second film is preferably greater than the thickness of the first film. film 2 for the reasons indicated below. According to the present example, the thickness of the second film 10 is 1 mm. It should be noted that the first film 2 and the second film 10 are of visual appearance and / or of different colors in order to delimit visually distinctive zones. The second film 10 differs from the first film 2 in that it deforms more easily than the first film to allow easier insertion and better maintenance of the first film by the second film.

[34] According to another so-called compression step illustrated in Figure 2, the punch 4 and the die 12 are aligned and brought together so that the first film 2 compresses the second film 10 to detach and drop part 1 1 of the second film in the bottom 20 of the cavity 14. Of course, the cavity 14 is deep enough to accommodate the portion 1 1 or opening of the second film. In other words, the first film 2 punches the second film 10 so as to form a passage 22 through the second film. Preferably, the passage 22 normally extends to the larger faces 9 of the second layer 10.

[35] According to another so-called positioning step illustrated in Figure 3, the punch 4 and the die 12 are then spaced apart so as to position the first film 2 in the passage 22. Preferably, the first film 2 is positioned so that flush a large face 9 of the second film 10. According to a variant not shown, the first film 2 is positioned to be set back from the large faces 9 of the second film 10.

[36] The method described here thus makes it possible to obtain a color screen 24A as illustrated in FIG. 4, comprising a first film 2 inserted in a second film 10 in order to delimit at the level of the same surface distinct zones. visually. For example, the first film and the second film can respectively be of chrome appearance and red color or vice versa. Advantageously, the first film 2 does not protrude from the second film 10, which on the one hand makes it possible to form a color screen 24A whose thickness is limited to the thickest film, in this case the second film 10, and secondly to allow a more homogeneous recovery of the color screen 24A by another layer if necessary, for example a protective layer. Indeed, the first film 2 can be positioned so as to flush with a large face 9 of the second film to form a smooth surface, favorable to the deposition of a regular layer. According to another advantage, the first and second films do not overlap this which preserves the light transmission properties of each film.

[37] In the example described above, it should be noted that the first film 2 is of shape and dimensions adapted to superimpose perfectly on the bearing face 6 of the punch 4 (see Figure 1). However, it may turn out that this is not the case and it is necessary to pre-format the first movie. FIGS. 5 and 6 illustrate a method of shaping the first film 2 of punching the first film against the die 12 so as to remove the portions 26 of the first film 2 protruding from the bearing face 6. Of course, the steps illustrated in Figures 5 and 6 are carried out prior to the steps illustrated in Figures 1 to 3.

[38] Figures 7 to 12 now illustrate a second embodiment of a method of a color screen 24B according to the invention. This example differs from the first example in that the first film 2 is now held at the punch 4 by means of auxiliary punches 28.

For this, the first film is placed on an auxiliary die 30 so as to completely cover two separate cavities 32 and opening on an upper face 34 of the auxiliary die 30. Each cavity 32 thus defines an opening 36 at the upper face 34 Each auxiliary punch 28 is of complementary shape to the openings 34 of the auxiliary die 30, so that the value of the cutting clearance between the auxiliary punches 28 and the auxiliary die 30 is less than 0.5 mm, preferably this value tends towards zero. The punch 4 is positioned above the first film 2 so that each auxiliary punch 28 is vis-à-vis with a cavity 32.

[39] The punch 4 and the auxiliary die 30 are then brought together so that each auxiliary punch 28 completely passes through the first film 2 as illustrated in FIG. 8. Thus, advantageously, the auxiliary punches 28 hold the first film 2 against the bearing surface 6 of the punch, thus playing the role of holding means described above. As illustrated in FIGS. 9 and 10, the auxiliary punches 28 are configured to hold the first film 2 to the punch 4 during the process of producing a color screen described above. More specifically, the side walls 38 of the auxiliary punches 28 are configured to maintain the first film 2 by a mechanical friction phenomenon. For this purpose, the side walls 38 may comprise a graining or grooves (not shown in the figures) to promote this phenomenon. Figures 9 and 11 represent steps similar to those shown in Figures 1 to 3.

[40] This second exemplary embodiment makes it possible to obtain a color screen 24B as illustrated in FIG. 12, comprising a first film 2 inserted in a second film 10 in order to visually delimit distinct zones at the same level. area. Unlike the first example described above, the first film 2 now comprises two passages 40 formed by the auxiliary punches 28. This embodiment is particularly advantageous for providing openings in the first film which may optionally be closed by a third film not shown, according to one of the methods described above. In other words, this second embodiment of the invention can make it possible to form films comprising a first film inserted in a second film and a third film inserted in the first film. The three films may be the same or different to form a complex nested pattern. [41] In this second example, it should be noted that the first film 2 is of shape and dimensions adapted to superimpose perfectly on the bearing face of the punch 4 (see Figure 8). However, this may not be the case and it is necessary to pre-format the first movie. FIGS. 13 to 16 illustrate a method of shaping the first film 2 of punching the first film against the auxiliary die 30 so as to remove the portions 40 of the first film 2 protruding from the bearing face 6. Naturally, the steps illustrated in Figures 13 to 16 are carried out prior to the steps illustrated in Figures 7 to 1 1.

[42] It should be noted that in the examples described above the films are flat. However, as mentioned above, the invention is not limited to the use of flat films. The skilled person can therefore easily adapt the above examples to make curved screens from first (s) and second (s) curved films.

[43] Of course, various other modifications to the device according to the invention may be contemplated within the scope of the appended claims.

Claims

1. A method of producing a color screen (24A, 24B) for a lighting and / or signaling device for a motor vehicle implementing the following steps:

a step of compressing a first film (2) against a second film

(10) of larger surface, so that the first film (2) perforates the second film (10) and thereby makes a passage (22) to the dimensions of the first film (2), the first and the second film being made of plastic and of different colors; then

- A positioning step of the first film (2) in the passage (22) so as to close said passage (22).

2. Method according to one of the preceding claims, characterized in that the first film (2) has a thickness of between 0.3 mm and 0.8 mm, preferably of the order of 0.5 mm.

3. Method according to one of the preceding claims, characterized in that the first film (2) is thinner than the second film (10).

4. Method according to the preceding claim, characterized in that the first film (2) is positioned in the second film (10) so as to be flush and / or recessed from a large face (9) of the second film (10). ).

5. Method according to one of the preceding claims, characterized in that the first film (2) is less easily deformed than the second film (10) under the same mechanical stress normally applied to their larger faces (8, 9) .

6. Method according to one of the preceding claims, characterized in that the first film (2) and / or the second film (10) is at least partially curved.

7. Method according to one of the preceding claims, characterized in that the first film (2) and / or the second film (10) is composed of a stack of layers.

8. Method according to one of the preceding claims, characterized in that the method is reproduced so as to produce a color screen comprising a plurality of first films (10).

9. Method according to one of the preceding claims, characterized in that prior to the compression step, the second film (10) is positioned against an upper face (16) of a matrix (12), the upper face ( 16) comprising at least one opening (14) of shape complementary to the contours of the first film (2) so as to receive the portion (1 1) of the second film (10) which is detached by the first film (2) during the compression step.

10. Method according to the preceding claim, characterized in that prior to the compression step, the contour of the first film (2) is cut so as to have a shape complementary to the opening (18) of the matrix (12) .

1 1. Method according to the preceding claim, characterized in that the value of the cutting clearance between the first film (2) and the opening (18) of the matrix (12) is between 0.01 and 0.1 mm.

12. Method according to one of the preceding claims, characterized in that the largest faces (8) opposite the first film (2) are connected by at least one passage (40).

13. Method according to the preceding claim, characterized in that at least one passage (40) is formed by means of an auxiliary punch (28), and in that the auxiliary punch (28) is inserted into the first film (2) prior to the step of compressing the first film against the second film (10), and in that the auxiliary punch (28) is removed from the first film (2) after the step of positioning the first film ( 2) in the second film (10).

14. Method according to the preceding claim, characterized in that the auxiliary punch (28) is mounted on a punch (4) so that the auxiliary punch (28) is projecting from a bearing face (6) of the punch (4) and that said face support (6) is superimposed substantially or preferably perfectly to the first film (2) during its punching by the auxiliary punch (28).

15. Method according to the preceding claim, characterized in that the bearing face (6) is of identical shape to the first film (2) so that the first film (2) is in contact with the entire bearing face ( 6) when punched by the auxiliary punch (28).