METHOD FOR MANUFACTURING AN AUTOSTEREOSCOPIC SCREEN AND METHOD FOR CONVERTING FROM A SCREEN FOR DISPLAYING A TWO-DIMENSIONAL IMAGE TO A SCREEN FOR DISPLAYING AN AUTOSTEREOSCOPIC IMAGE

Abstract

The invention relates to a manufacturing method for a screen for displaying an autostereoscopic image, including the steps of: selecting (E10) a block of pixels which are arranged in rows and columns, each pixel being composed of a plurality of sub-pixels of different colors; selecting (E11) a polarization film; manufacturing (E12, E13, E14) a lenticular array directly on the polarization film in order to form a composite film, called optical film; bonding (E15) the optical film to the block of pixels. The invention also relates to a method for converting a screen for displaying a two-dimensional image into a screen for autostereoscopic display.

Claims

1. A method for manufacturing a screen for displaying an autostereoscopic image, comprising the steps of: selecting a block of pixels which are arranged in rows and by columns, each pixel being composed of a plurality of sub-pixels of different colors, selecting a polarization film having a first optical axis, manufacturing a lenticular array directly on said selected polarization film to form a composite film, called optical film, said lenticular array having a second optical axis, and bonding said optical film on said selected block of pixels so as to obtain a polarizing and lenticular display screen having two optical axes associated respectively with a polarization function and an autostereoscopic function.

2. The method according to claim 1, wherein said step for manufacturing a lenticular array directly on said polarization film comprises: applying a layer of transparent polymerizable resin on said polarization film, implanting said lenticular array in said layer of polymerizable resin, and polymerizing said polymerizable resin so as to obtain a transparent and stable composite film integrating said lenticular array.

3. The method according to claim 2, wherein said transparent polymerizable resin is a resin, (one-component or two-component), polymerizable by UV or by chemical reaction following mixing with another component, or by the addition of heat.

4. The method according to claim 2, wherein said step consisting in implanting said lenticular array in said polymerizable resin layer consists in laminating said polarization film with a cylinder engraved with the shapes and dimensions of the desired lenticular array.

5. The method according to claim 2, wherein said step consisting in implanting said lenticular array in said polymerizable resin layer consists in printing said polarization film by means of a UV varnish printer a pattern in the shapes and dimensions of the desired lenticular array.

6. The method according to claim 2, wherein said step consisting in implanting said lenticular array in said polymerizable resin layer consists in screen printing said polarization film in the shapes and dimensions of the desired lenticular array.

7. The method according to claim 2, wherein said step consisting in implanting said lenticular array in said polymerizable resin layer consists in applying a mold on said polarization film in the shapes and dimensions of the desired lenticular array.

8. The method according to claim 2, wherein said selected polarization film is formed from a film of polyvinyl oxide stretched and laminated between two films of cellulose triacetate.

9. A method for converting a 2D screen for displaying a two-dimensional image into a 3D screen for displaying an autostereoscopic image, said 2D screen comprising at least one layer of liquid crystals forming a block of pixels, overlaid at least by a polarization film, said method comprising the steps of: peeling said polarization film off of said 2D screen, selecting a polarization film, manufacturing a lenticular array directly on said selected polarization film to form a film, called optical film, and bonding said optical film directly onto said block of pixels of said 2D screen.

10. The method according to claim 9, wherein said step for manufacturing a lenticular array directly on said polarization film comprises the: applying a layer of transparent polymerizable resin on said polarization film, implanting said lenticular array in said layer of polymerizable resin, and polymerizing said polymerizable resin so as to obtain a transparent and stable composite film integrating said lenticular array.

11. A method for manufacturing a lenticular array on a polarization film, comprising: applying a layer of transparent polymerizable resin on said polarization film, implanting said lenticular array in said layer of polymerizable resin, and polymerizing said polymerizable resin so as to obtain a transparent and stable composite film integrating said lenticular array.

Description

LIST OF FIGURES

[0062] Further aims, features and advantages of the invention will become apparent upon reading the following description, which is provided solely by way of non-limiting example, and which refers to the accompanying figures, in which:

[0063] FIG. 1 is a synoptic schematic view of a method according to one embodiment of the invention.

[0064] FIG. 2 is a schematic view of a device making it possible to implement the step of implanting a lenticular array on a polarization film of a method according to one embodiment of the invention.

DETAILED DESCRIPTION OF ONE EMBODIMENT OF THE INVENTION

[0065] As shown in FIG. 1, a method according to a preferred embodiment comprises a step E10 for selecting a block of pixels, a step E11 for selecting a polarization film, a step E12 for applying a layer of polymerizable resin directly to the selected polarization film, a step E13 for implanting a lenticular array in the resin layer deposited on the polarization film, a step E14 for polymerizing the resin so as to obtain a transparent and stable composite film integrating the lenticular array and a step E15 for bonding the composite film thus formed on the selected block of pixels.

[0066] At least one embodiment of each of these steps will now be described in detail.

[0067] Step E10 for selecting a block of pixels consists in choosing a block of pixels with dimensions that are compatible with the targeted application. Such a block of pixels can be of any known type. The block comprises pixels arranged by rows and by columns and each pixel is composed of a plurality of sub-pixels of different colors.

[0068] Step E11 for selecting a polarization film consists in choosing a polarization film, with dimensions compatible with the selected block of pixels.

[0069] In the case of a method for converting a 2D screen into a 3D screen, steps E10 and E11 consist in peeling the polarization film off of the considered 2D screen and in selecting the block from the 2D screen to be converted as the block of pixels.

[0070] It is also possible to bond a transparent film to this polarization film in order to form a new polarization film which is then treated by the method according to the invention. It is also possible to manufacture the lenticular array directly onto a transparent film and then to bond it directly on a polarizer which is not bonded to the screen. This variant thus makes it possible to obtain a new composite film which is bonded to a screen which no longer has a polarizer, or to a screen which is already equipped with a polarizer, thus doubling the thickness of the initial polarizer by adding the thickness and the function of the additional transparent lenticular film to it. This may in particular be necessary if the lenticular array to be implanted on the polarization film must not be in direct contact with the original polarization film, but slightly spaced apart from the latter, in particular given the optical focal length requirements.

[0071] It is also possible to adapt a method of converting a 2D screen into a 3D screen according to the invention by forming a lenticular array on a transparent film, instead of forming it on a polarization film, and bonding this lenticular array thus formed directly on the surface of the 2D screen from which the original polarization film has been removed. The conversion method then consists in bonding the polarization film previously peeled off of the 2D screen or another polarization film, mounted on a rigid substrate, on the lenticular array bonded to the block of pixels of the 2D screen.

[0072] According to one embodiment of the invention, step E12 for applying a resin layer on the polarization film, step E13 for implanting a lenticular array on said polarization film and step E14 for polymerizing the resin on the polarization film are interwoven and carried out in a coordinated manner. This step can for example be implemented by the device shown schematically in FIG. 2.

[0073] To do this, an engraved metal cylinder 20 (having a polished glass surface state and grooves with shapes and dimensions conforming exactly to the lenses of the lenticular array to be produced) is placed on a platform consisting of two rollers 21, 22, for example made from rubber, which each extend in the same direction. The axes of the two rollers are therefore parallel. Each roller 21, 22 is driven in rotation by an electric motor, not shown in FIG. 2 (of course, any other means for driving each of the rollers in rotation is possible to achieve a substantially identical result). According to another variant described later, only one rubber roller is motorized.

[0074] The rollers 21, 22 are spaced apart from one another in the direction perpendicular to the direction of their axis of rotation, so as to allow the passage of UV light or visible light, but close enough to retain the engraved metal cylinder 20, which is placed on the two rollers.

[0075] The selected polarization film 25 (or the polarization film peeled off of the 2D screen in the case of a conversion of a 2D screen into a 3D screen) is conveyed between the two rubber rollers 21, 22 and the engraved cylinder 20. In other words, the polarization film 25 is sandwiched between the two rubber rollers from below, and the engraved metal cylinder from above.

[0076] The polarization film is held stretched, to keep it tangent to the two rubber rollers and the engraved metal cylinder. This tensioning action of the polarization film can be obtained by any type of means.

[0077] The UV resin is then deposited in contact with the metal cylinder on the surface of the polarization film, upstream of this cylinder. The arrow 26 schematically shows the pouring of the resin upstream of the cylinder. The upstream side of the cylinder is defined by the direction of rotation of the cylinder and of the advance of the polarization film (from right to left in the illustration of FIG. 2). In other words, the resin is deposited just before the film 25 passes under the cylinder 20. This displacement of the polarization film in a direction, called the direction of advance, perpendicular to the axis of rotation of the rubber rollers and of the engraved cylinder is obtained by friction of the film between the rubber rollers and the engraved cylinder.

[0078] The synchronized rotation of the two rubber rollers 21, 22, the engraved cylinder 20, and the movement of the polarization film 25 along the direction of advance forces the resin to pass under the engraved cylindrical roller 20.

[0079] According to a variant of the invention, only one rubber roller is motorized and drives the engraved film, the engraved cylinder and the other rubber roller by friction.

[0080] When the resin passes under the metal cylinder between the latter and the film stretched on its surface, said resin polymerizes and freezes due to the flow of UV light and/or visible light that it receives between the rubber rollers, which together form a diaphragm.

[0081] Depending on the resin used, it may be necessary to treat the surface of the engraved cylinder to ensure that the resin adheres better to the polarization film than to the metal cylinder so that the film carries the cured resin as it exits between the engraved cylinder and the rubber rollers.

[0082] The polarization film 25 thus obtained has, on its surface, the negative of the engravings of the cylinder 20, made of transparent material, forming a lenticular array which perfectly conforms in pitch and focal length to the targeted lenticular array.

[0083] Thus and as schematically shown in FIG. 2, the polarization film 25 at the outlet of the device (on the left in the figure) has a lenticular array on the surface of the film, while the surface of the film upstream of the device has no array.

[0084] The emission of UV and/or visible light 27 can be obtained by any known means. The method can nevertheless be facilitated by preventing an increase in temperature during the various stages of the described method leading to geometric alterations of the metal cylinder and/or of the polarization film. Therefore, an infrared filter and ventilation can advantageously be implemented during the implantation operations of the lenticular array to avoid such a temperature increase and thus to improve the results of the method according to this embodiment, in particular.

[0085] Finally, the last step, E15, which bonds the composite film thus formed on the selected block of pixels, can be carried out by any known means. In particular, this bonding step can be implemented by the same means as the step of bonding a conventional polarization film onto a standard 2D block of pixels. This is, in particular, one of the advantages of a method according to the invention, which can be integrated without particular difficulties into a 2D screen manufacturing method by simply modifying the step of manufacturing the polarization film, in order to design autostereoscopic screens, thus substantially reducing the manufacturing costs of such screens.

[0086] The described method is only one embodiment of the invention. It is also possible to carry out the invention by replacing the use of an engraved metal cylinder with the implementation of a UV varnish printer directly onto the polarization film to form the desired lenticular array. It is also possible to screen print said polarization film with the shapes and dimensions of the desired lenticular array. It is also possible to apply a mold to the polarization film, this mold being in the same shape and dimensions of the desired lenticular array.

[0087] According to another embodiment, it is also possible to produce the lenticular array with a UV resin which has a relatively high refractive index with a lens profile corresponding to a focal length which is much shorter than the desired one. It is then possible to modify the focal length by embedding the first lenticular array with a resin of much lower refractive index in order to compensate for the modification of the voluntarily chosen radius of curvature. The advantage of such a method lies in the fact that, in the latter case, the active diopter is embedded in the heart of a device integrating two transparent components with two different indices. In this case, the lenticular array can be completely included between two flat surfaces. On one side, the screen surface, and on the other, a glass or plastic plate acting as a protective and finishing plate, either slightly frosted or anti-reflective or the like.