Method for manufacturing liquid crystal display device and liquid crystal display device

Abstract

The present invention relates to a method for manufacturing a liquid crystal display device (1; 30), the liquid crystal display device comprising a reflective or transflective liquid crystal unit (2; 32), the liquid crystal unit (2; 32) comprising a transparent front substrate (4) located on the side of an observer (6) and a transparent rear substrate (8), the liquid crystal display device (1; 30) being provided with a reflective polarizing film (18; 34) for absorbing a first component of light (20) entering the liquid crystal unit (2; 32) through the front substrate (4) and reflecting a second component of the light (20) polarized in a direction orthogonal to the direction of the first component, the method comprising: forming a convex structure of the reflective polarizing film (18; 34) so ​​that it has a decorative and / or functional shape, the shape being visible to an observer (6) through the front substrate (4) of the liquid crystal unit (2; 32), and then fixing the reflective polarizing film (18; 34) to the lower side (22) of the rear substrate (8).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a liquid crystal display device and a liquid crystal display device obtained by the method. In particular, the present invention relates to a manufacturing method for providing a liquid crystal display device with a decorative and / or functional pattern, which is visible through a transparent display surface of the liquid crystal display device. Background Art

[0002] The present invention relates to display devices of the digital type, ie display devices capable of displaying information in alphanumeric form, as distinct from analogue display devices which display information by means of one or more pointers which move relative to a scale.

[0003] A well-known class of digital display devices is the liquid crystal display device. These liquid crystal display devices generally comprise a liquid crystal cell formed by a transparent front substrate on the observer's side and a rear substrate, which may be transparent or opaque, extending parallel to and at a distance from the front substrate. The two substrates are generally connected to each other by a sealing frame which defines a sealed enclosure in which the liquid crystal composition is confined. Finally, the front and rear substrates are coated on their opposite faces with conductive transparent electrodes and counter electrodes; the application of an electric field between an electrode and a corresponding counter electrode changes the optical properties of the liquid crystal composition at the intersection of the relevant electrode and counter electrode.

[0004] In the scope of the present invention, we are concerned with the following types of liquid crystal cells:

[0005] -Twisted nematic or "TN" type;

[0006] -Super twisted nematic or "STN" type;

[0007] -Guest Host type;

[0008] - Vertical Alignment or "VA"; and

[0009] -Electrically controlled birefringence or "ECB" type.

[0010] In order to be able to operate in reflective mode, a TN, STN, guest-host or VA or ECB liquid crystal cell must be equipped with a reflective polarizer, which is usually stacked / laminated on the lower surface of the rear substrate and whose function is to reflect light that enters the liquid crystal cell through the front surface / front side of the rear substrate and passes through the entire liquid crystal cell until it is reflected on the polarizer.

[0011] There are several types of reflective polarizers, which provide either specular reflection or diffuse / diffuse reflection, depending on the situation. The first type of reflective polarizer consists of an absorptive / transmissive polarizer. This type of polarizer absorbs a first component of light and transmits another component of light polarized in a direction perpendicular to the first component. To form a reflective polarizer, the underside of the absorptive / transmissive polarizer is equipped with a reflector, such as a thin metal layer of aluminum or silver, on which the light transmitted by the absorptive / transmissive polarizer is reflected and returned upward through the liquid crystal cell toward the viewer.

[0012] In the case of a transflective / transflective liquid crystal cell that is both reflective and transmissive, the polarizer must be partially reflective and transmissive. In order to obtain such a partially reflective and transmissive polarizer, one solution consists in reducing the thickness of the metal layer coating the absorptive polarizer to very low values ​​- in the order of a few nanometers, which is precisely controlled. In addition, such a transflective liquid crystal cell is equipped with a backlight device arranged under the rear substrate, which emits light through the partially reflective / transmissive polarizer to the top of the liquid crystal cell.

[0013] Another solution to allow TN, STN, guest-host, VA or ECB type liquid crystal cells to operate in reflective mode is to provide such liquid crystal cells with a reflective / transmissive polarizer that reflects the polarization component of the light in one direction and transmits the polarization component of the light in an orthogonal direction. This type of reflective / transmissive polarizer can be of the "co-extruded multilayer birefringent interference polarizer" type (for example, the polarizer sold by 3M under the brand "Dual Brightness Enhancement Film") or of the "wire grid polarizer" type. The reflective / transmissive polarizer is fixed to the underside of the rear substrate, for example by lamination, and a black or colored / colored background layer is subsequently added to absorb the light that must not be reflected. In the case where it is desired to obtain a semi-transmissive and semi-reflective liquid crystal cell, the black or colored background layer will only partially absorb to allow the light generated by the backlight device arranged below the rear substrate to pass.

[0014] There is also a display device including a liquid crystal cell having a single polarizer disposed on an upper surface of a front substrate thereof and a metal reflector disposed between the front substrate and a rear substrate thereof.

[0015] Existing liquid crystal display devices including TN type, STN type, guest-host type, VA type or ECB type display cells therefore display information in the form of alphanumeric characters or icons that stand out on a uniform flat background layer of specular reflection or diffuse reflection type. As a result, there is little possible variation in appearance between these existing liquid crystal display devices, making it difficult for manufacturers to stand out. Likewise, objects equipped with such liquid crystal display devices, such as watches, have very similar appearances. Summary of the invention

[0016] One of the objects of the present invention is to overcome the above problems by providing a manufacturing method which makes it possible to manufacture a reflective or transflective liquid crystal display device whose appearance can be infinitely varied. Another object of the present invention is to provide a reflective or transflective liquid crystal display device with an original aesthetic appearance.

[0017] To this end, the present invention relates to a method for manufacturing a liquid crystal display device, the liquid crystal display device comprising a reflective or semi-transmissive and semi-reflective liquid crystal unit, the liquid crystal molecules of the liquid crystal unit are arranged / oriented in a planar / horizontal or vertical / vertical manner, the liquid crystal unit comprises a transparent front substrate and a transparent rear substrate located on the observer side, the rear substrate extends below the front substrate parallel to the front substrate and at a certain distance from the front substrate, the front and rear substrates are connected to each other by a sealing frame, the sealing frame defines a sealed housing, the liquid crystal composition is confined in the sealed housing, the front substrate and the rear substrate are coated with conductive transparent electrodes on their opposite surfaces. The invention relates to a liquid crystal display device comprising a plurality of liquid crystal display devices, wherein the liquid crystal display device comprises a plurality of electrodes and a counter electrode, wherein the optical properties of the liquid crystal composition are changed by applying an electric field at the intersection between the electrodes and the corresponding counter electrode, the liquid crystal display device is provided with a reflective polarizing film, the reflective polarizing film being arranged to absorb a first component of light entering the liquid crystal cell through the front substrate and reflect a second component of the light polarized in a direction orthogonal to the direction of the first component, the manufacturing method comprising the steps of forming a convex / embossed / concave-convex structure of the reflective polarizing film so as to have a decorative and / or functional shape which is visible to an observer through / transmitting the front substrate of the liquid crystal cell, and then fixing the reflective polarizing film to the lower side / bottom side of the rear substrate.

[0018] -According to a specific embodiment of the present invention:

[0019] - forming a relief structure of the reflective polarizing film by pressing it against a mold having a concave-convex shape corresponding to the shape desired to be imprinted on the reflective polarizing film;

[0020] - Pressing the polarizing film against the mold having a concave-convex shape by generating a gas vacuum;

[0021] - the reflective polarizing film is heated while it is pressed against the mold having a concavo-convex shape;

[0022] - The reflective polarizing film is formed into a relief structure by insert injection molding;

[0023] - once the reflective polarizing film has been formed into a relief structure, a transparent leveling layer and an adhesive layer are successively deposited on the upper surface of the reflective polarizing film, by means of which the reflective polarizing film is fixed to the liquid crystal cell;

[0024] - immediately after forming the reflective polarizing film into a relief structure and depositing the transparent leveling layer, applying the liquid crystal cell to the transparent leveling layer and curing the transparent leveling layer;

[0025] - the adhesive layer is formed of an optically clear adhesive, also called optically clear adhesive or "OCA", which takes the form of a pressure-sensitive / pressure-sensitive film laminated / laminated onto the transparent planarization layer or is dispensed as a liquid adhesive layer onto the transparent planarization layer;

[0026] - the light-transmissive adhesive is partially diffusely reflective;

[0027] - Depositing a transparent leveling layer on the back side of the reflective polarizing film;

[0028] - the transparent leveling layer deposited on the upper surface of the reflective polarizing film, and possibly on the back surface of the reflective polarizing film, is obtained by means of a photopolymerizable resin;

[0029] - the transparent planarization layer deposited on the upper surface of the reflective polarizing film, and possibly on the back surface of the reflective polarizing film, is polymerized by ultraviolet radiation;

[0030] - providing a diffusing layer on the upper surface of the reflective polarizing film before forming the relief structure, so as to produce at least a partial diffuse reflection;

[0031] - the reflective polarizing film comprises a reflective polarizer combined with an at least partially absorbing background layer arranged on the back side of the reflective polarizer;

[0032] - the at least partially absorbing background layer is black or colored;

[0033] - the black or colored background layer is an ink layer or a laminate film, which is applied to the back side of the reflective polarizer before the reflective polarizer is formed, so that the black or colored background layer is formed simultaneously with the reflective polarizer, or is applied to the back side of the reflective polarizer after the reflective polarizer is formed;

[0034] - when the background layer is partially absorbent, the backlight is arranged below the background layer;

[0035] - the reflective polarizing film comprises a reflective polarizer combined with an absorptive polarizer bonded / adhered to the back side of the reflective polarizer, the assembly consisting of the two polarizers, reflective and absorptive, forming a relief structure at the same time;

[0036] - the reflective polarizing film comprises an absorbing polarizer in combination with an at least partially reflective polarizer (a polarizer having at least partial reflectivity) arranged below the absorbing polarizer;

[0037] - the reflector is a metal reflector;

[0038] - When the reflector is partially reflective, the backlight is arranged below the reflective polarizing film.

[0039] The present invention also relates to a liquid crystal display device, which includes a reflective or semi-transmissive and semi-reflective liquid crystal unit, the liquid crystal molecules of which are arranged / oriented in a planar / horizontal or vertical manner, the liquid crystal unit including a transparent front substrate and a transparent rear substrate located on the observer side, the rear substrate extending parallel to the front substrate and at a certain distance from the front substrate below the front substrate, the front and rear substrates are connected to each other by a sealing frame, the sealing frame defines a sealed shell, the liquid crystal composition is confined in the sealed shell, the front substrate and the rear substrate are coated with conductive transparent electrodes and counter electrodes on their relative surfaces, the optical properties of the liquid crystal composition are changed by applying an electric field at the intersection between the electrodes and the corresponding counter electrodes, the liquid crystal display device is provided with a reflective polarizing film to absorb a first component of light entering the liquid crystal unit through the front substrate and reflect a second component of the light polarized in a direction perpendicular to the first component, the reflective polarizing film has a decorative and / or functional convex pattern portion visible to the observer through the front substrate of the liquid crystal unit, and the reflective polarizing film is fixed to the lower side of the rear substrate.

[0040] According to a specific embodiment:

[0041] - the reflective polarizing film comprises a reflective polarizer combined with an at least partially absorbing background layer arranged on the back side of the reflective polarizer;

[0042] - the at least partially absorbing background layer is black or colored;

[0043] - The black or colored background layer is an ink layer or laminate film applied to the back side of the reflective polarizer;

[0044] - a reflective polarizing film comprising a reflective polarizer combined with an absorptive polarizer bonded to the back of the reflective polarizer, the assembly consisting of two polarizers, the reflective and the absorptive, forming a relief structure;

[0045] - the reflective polarizing film comprises an absorbing polarizer in combination with an at least partially reflective polarizer arranged below the absorbing polarizer;

[0046] - the reflector is a metal reflector;

[0047] - When the reflector is partially reflective, the backlight is arranged below the latter.

[0048] The invention also relates to a timepiece comprising a display device of the above type.

[0049] Thanks to these characteristics, the present invention provides a method for manufacturing a reflective or transflective liquid crystal display device that displays letters, numbers or other information on a relief background that has innovative aspects that are very different from each other. This result is achieved by teaching the imprinting of a relief shape on a reflective polarizing film that is visible to the naked eye of the watch wearer when the wearer views the effective display surface of the liquid crystal cell. In particular, in the case where the liquid crystal display device according to the present invention is installed in a watch, the reflective polarizing film can form a relief structure so that it has a texture that imitates the appearance of a traditional watch dial: "Clous de Paris", "Côtes de Genève", etc. de Genève), textured effects, sunrays / sunbursts, engine-turned or "guillochage" dials, etc. It is also possible to emboss the reflective polarizing film with simple height variations in order to highlight the presence of the active display surface of the liquid crystal cell, areas showing segments or areas with or without texture. Finally, by means of the invention it is also possible to emboss the reflective polarizing film with graphic patterns, such as plant patterns, or patterns inspired by embossed decorations / carved patterns, coin surfaces, sculptures or even bas-reliefs. Thus, the invention enables manufacturers of watches or other electronic products comprising reflective or transflective liquid crystal display devices to offer their customers objects that are aesthetically novel and stand out from the competition, while using conventional liquid crystal technology that is well mastered and therefore reliable and inexpensive. The possibility of easily changing the background decoration of the liquid crystal display device provided by the invention allows the manufacturer to have a wide variety of products, each with a different aesthetic appearance, but based on a common technological platform, which makes it possible to share the production costs. For example, the shapes of the segments and icons of the liquid crystal cells according to the invention can be common to several display devices, which still have different decorative and / or technological elements. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Other characteristics and advantages of the invention will become more apparent from the following detailed description of an embodiment of the method according to the invention, an example of which is given entirely by way of non-limiting illustration with reference to the accompanying drawings, in which:

[0051] - Figure 1 is a cross-sectional view of a liquid crystal display device including a liquid crystal cell provided with a reflective polarizing film including a reflective polarizer combined with a black or colored background layer.

[0052] - Figure 2 is a cross-sectional view of a liquid crystal display device including a liquid crystal cell provided with a reflective polarizing film including an absorbing polarizing film combined with a metal reflector.

[0053] - Figure 3 is a schematic cross-sectional view of a reflective polarizing film comprising a reflective polarizer and a black background layer provided with a convex pattern, wherein the cavities / recesses of the reflective polarizing film are filled with a transparent leveling layer.

[0054] - Figure 4 is similar to Figure 3 , where the transparent leveling layer itself is coated with an optically clear adhesive layer.

[0055] - Figure 5 A reflective polarizing film is shown bonded to the underside of the rear substrate of a liquid crystal cell via an optically clear adhesive layer.

[0056] - Figure 6 is a schematic cross-sectional view of a reflective polarizing film bonded directly to the underside of the rear substrate of a liquid crystal cell via a transparent planarization layer.

[0057] - Figure 7 is a schematic cross-sectional view of a reflective polarizing film formed into a relief structure having a diffusing layer on its upper surface that produces at least partial diffuse reflection.

[0058] - Figure 8 is a schematic cross-sectional view showing that a reflective polarizing film provided with a diffusion layer is bonded to the lower side of a rear substrate of a liquid crystal cell by means of an optically clear adhesive layer.

[0059] - Fig. 9 is a schematic cross-sectional view showing a reflective polarizing film bonded by means of an optically diffusely reflective adhesive layer, the reflective polarizing film comprising a reflective polarizer combined with a black or colored background layer and on which a transparent planarizing layer has been deposited.

[0060] - Fig.10 Schematically shown is a cross-sectional view of an assembly formed by a reflective polarizer and an absorptive polarizer, which are formed into a relief structure and fixed to the underside of the rear substrate of a liquid crystal cell via a transparent leveling layer and an adhesive layer, with a backlight device arranged below the stack.

[0061] - Fig.11 is a schematic cross-sectional view of a liquid crystal cell provided with a reflective polarizer which, once formed into a relief structure, receives in a cavity on its rear side a transparent planarizing layer to which an absorbing polarizer is laminated / laminated on its flat face, the assembly being completed by a backlight arrangement arranged below the liquid crystal cell.

[0062] - Fig.12 A cross-sectional view of a liquid crystal cell provided with a reflective polarizing film comprising an absorbing polarizer combined with a reflective reflector is schematically shown.

[0063] - Fig.13 is similar to Fig.12 A view of a backlight device arranged below a liquid crystal unit,

[0064] - Fig.14 is a view of a watch equipped with a liquid crystal unit whose reflective polarizing film arranged at the lower part of the liquid crystal display device has formed a convex structure to display a jade relief-like image through the effective display surface of the liquid crystal unit. DETAILED DESCRIPTION

[0065] Figure 1 1 is a cross-sectional view of a liquid crystal display device generally indicated by reference numeral 1. The liquid crystal display device 1 comprises a liquid crystal cell 2, which comprises a transparent front substrate 4 located on the side of an observer 6 and a rear substrate 8, which is also transparent, extending below the front substrate 4, parallel to the front substrate 4 and at a distance from the front substrate 4. The two substrates, the front substrate 4 and the rear substrate 8, are connected to each other by a sealing frame 10, which defines a sealed housing 12, in which a liquid crystal composition is confined. The front substrate 4 and the rear substrate 8 are coated with conductive transparent electrodes 14 and counter electrodes 16 on their opposite surfaces. The optical properties of the liquid crystal composition are changed by applying an electric field at the intersection between the electrode 14 and the corresponding counter electrode 16. The liquid crystal cell 2 is provided with a reflective polarizing film 18, which is arranged to absorb a first component of light 20 entering the liquid crystal cell 2 through the front substrate 4 and reflect a second component of the light polarized in a direction orthogonal to the direction of the first component.

[0066] Figure 1 The liquid crystal cell 2 shown is reflective or at least semi-transmissive and semi-reflective. To this end, the liquid crystal cell 2 is provided with a reflective polarizing film 18 fixed to the lower side 22 of the rear substrate 8. The reflective polarizing film 18 comprises a reflective polarizer 24 combined with a black or colored background layer 26, which can be formed by an ink layer or a laminated film. Depending on whether the background layer 26 is partially absorbing or completely absorbing, the liquid crystal cell 2 is semi-transmissive and semi-reflective or reflective. In the case where the liquid crystal cell 2 is semi-transmissive and semi-reflective, a backlight device 28 is arranged below the reflective polarizing film 18.

[0067] The reflective polarizer 24 is bonded to the underside 22 of the rear substrate 8 by means of an adhesive layer 25 formed of an optically clear adhesive (also referred to as a light-transmissive adhesive or "OCA"). Likewise, a background layer 26 is bonded below the reflective polarizer 24 by means of an adhesive layer 27. Finally, the liquid crystal cell 2 also includes an absorbing polarizer 29, which is bonded to the upper surface 31 of the front substrate 4 by means of an adhesive layer 33.

[0068] Figure 2 is a cross-sectional view of a liquid crystal display device 30 including a liquid crystal cell 32. Figure 1 The difference of the liquid crystal display device 1 shown is that the reflective polarizing film 34 includes an absorptive polarizer 36 combined with an at least partially reflective reflector (a reflector having at least partial reflectivity) 38. When the reflector 38 (preferably but not limited to a metal reflector) is only partially reflective (only partially reflective), the liquid crystal cell 32 is semi-transmissive and semi-reflective, and the backlight device 28 is arranged below the reflective polarizing film 34.

[0069] With reference Figure 1 Similar to the described liquid crystal cell 2, the liquid crystal cell 32 is provided with an absorbing polarizer 29, which is bonded to the upper surface 31 of the front substrate 4 by means of an adhesive layer 33, and the absorbing polarizer 36 is bonded to the lower side 22 of the rear substrate 8 by means of an adhesive layer 25, and the reflector 38 is bonded to the bottom of the absorbing polarizer 36 by means of an adhesive layer 27.

[0070] The following description will be made with reference to a liquid crystal cell provided with a reflective polarizing film 18 comprising a reflective polarizer 24 combined with an at least partially absorbing black or colored background layer 26. It goes without saying that this example is given purely by way of illustration and that the same method can be applied to a liquid crystal cell provided with a reflective polarizing film 34 consisting of an absorbing polarizer 36 and an at least partially reflective reflector 38.

[0071] It is desirable to emboss the reflective polarizing film 18 with a relief shape that can be seen by the naked eye of the observer 6 when the observer 6 observes the effective display surface 40 of the liquid crystal cell 2. Therefore, when the liquid crystal cell 2 is installed in, for example, a watch, the reflective polarizing film 18 can be formed with a relief structure to have a texture that imitates the appearance of a traditional watch dial: "Clous de Paris", "Côtes de Genève", etc. de Genève, textured effects, sunray / sunburst, engine-turned or “guilloché” dials, etc. The reflective polarizing film 18 can also be embossed with graphic or technical shapes, such as plant patterns, or patterns inspired by relief ornaments, coin surfaces, sculptures or even bas-reliefs.

[0072] To achieve this result, reflective polarizer 24 is embossed by pressing reflective polarizer 24 against a mold having a concave-convex shape that corresponds to the shape desired to be embossed on reflective polarizer 24. Preferably, reflective polarizer 24 is pressed against the mold having a concave-convex shape by creating a gas vacuum, and even more preferably, reflective polarizer 24 is heated, for example by radiation, during the pressing of reflective polarizer 24 against the mold having a concave-convex shape. Thus, reflective polarizer 24 faithfully conforms to even the smallest concave-convex structural details of the mold and is fixed in position when cooled. After cooling, transparent planarization layer 42 ( Figure 3 ) is deposited in the cavity of the reflective polarizer 24. Finally ( Figure 4 ), the transparent planarization layer 42 is coated with an adhesive layer 44 formed of an optically clear adhesive or an "OCA" type optically clear adhesive. The adhesive layer 44 takes the form of a pressure-sensitive film that is laminated to the transparent planarization layer 42 on the side facing the liquid crystal cell 2, or is dispensed as a liquid adhesive layer onto the transparent planarization layer 42. The adhesive layer 44 allows the reflective polarizing film 18 to be ultimately bonded to the lower side 22 ( Figure 5 ).

[0073] The black or colored background layer 26 is an ink layer or a laminate film, which is applied to the back side 46 of the reflective polarizer 24 before the reflective polarizer 24 is formed so that the black or colored background layer 26 is formed simultaneously with the reflective polarizer 24, or is applied to the back side 46 of the reflective polarizer 24 after the reflective polarizer 24 is formed.

[0074] Therefore, it should be understood that the reflective polarizer 24 can be formed first and then coated with the black or colored background layer 26, or the reflective polarizing film 18 formed by the reflective polarizer 24 and its black or colored background layer 26 can be formed immediately / simultaneously. For ease of reading and understanding, it will be assumed in the following description that we are dealing with a complete reflective polarizing film 18.

[0075] According to a specific embodiment, the relief structure is formed by pressing the entire reflective polarizing film 18 against a mold having a concave-convex shape using a gas vacuum without heating. Then, a transparent leveling layer 42 formed of a photopolymerizable adhesive, such as one that is sensitive to ultraviolet radiation, is deposited in the cavities of the reflective polarizing film 18. Before or after the transparent leveling layer 42 is polymerized, an optically clear adhesive layer 44 is deposited on the transparent leveling layer 42.

[0076] according to Figure 6 In the particular embodiment shown, immediately after embossing the reflective polarizing film 18 and depositing the planarizing layer 42 formed of a photopolymerizable resin, the reflective polarizing film 18 is applied to the liquid crystal cell 2 through its transparent planarizing layer 42 and the transparent planarizing layer 42 is polymerized by ultraviolet radiation.

[0077] According to a variation not shown in the drawings, the reflective polarizing film 18 is formed into a convex structure by a method known as insert injection molding. The method includes arranging the reflective polarizing film 18 between a mold having a concave-convex shape and a flat relative mold, the convex shape corresponding to the shape desired to be embossed on the reflective polarizer 24. A transparent material such as an epoxy resin material, a thermoplastic polymer or a silicone resin material is then injected between the relative mold and the reflective polarizing film 18. When the mold is removed, this transparent material will form a transparent leveling layer. Under the action of the injection pressure, the reflective polarizing film 18 is heated directly or by the injected transparent material, and is forced to conform to the contour of the mold. The adhesive layer can be inserted between the relative mold and the transparent material, or applied to the flat surface of the transparent leveling material once the mold is removed.

[0078] In order to make the information displayed by the liquid crystal cell 2 in the form of alphanumeric characters or icons stand out against the uniform diffusely reflecting background layer, a light-permeable adhesive that is at least partially diffusely reflecting can be used. Before embossing the reflective polarizing film 18, the upper surface 48 of the reflective polarizing film 18 can also be provided with a diffuse layer 50 in order to produce at least a partial diffuse reflection ( Figure 7 After the diffusion layer 50 is deposited and the reflective polarizing film 18 is printed, the diffusion layer 50 is coated with a transparent leveling layer 42 and then the reflective polarizing film 18 is bonded to the underside 22 of the rear substrate 8 of the liquid crystal cell 2 by means of an optically clear adhesive layer 44 ( Figure 8 ).

[0079] Similarly, after forming the reflective polarizing film 18 including the reflective polarizer 24 combined with the black or colored background layer 26 into a relief structure and depositing the transparent planarization layer 42 in the cavities of the reflective polarizing film 18, the reflective polarizing film 18 can be formed with the aid of the optical diffuse reflective adhesive layer 52 ( Fig. 9 ) is fixed to the lower side 22 of the rear substrate 8 of the liquid crystal cell 2.

[0080] like Fig.10 As shown, the black or colored background layer 26 applied to the back side 46 of the reflective polarizer 24 is replaced by an absorptive polarizer 54 bonded to the back side 46 of the reflective polarizer 24. The assembly formed by the reflective polarizer 24 and the absorptive polarizer 54 is then embossed, and then a transparent leveling layer 42 is deposited in the cavity of the reflective polarizer 24. This transparent leveling layer 42 is coated with an adhesive layer 44, by means of which the assembly formed by the reflective polarizer 24 and the absorptive polarizer 54 is fixed to the lower side 22 of the rear substrate 8. Finally, the backlight 28 is arranged below the liquid crystal cell 2.

[0081] Likewise, as attached to this patent application Fig.11As shown, a transparent planarization layer 56 may also be deposited in the cavity of the reflective polarizer 24 on the back side 46 of the reflective polarizer 24. The flatness of the transparent planarization layer 56 may be advantageously used for laminating other films, such as an absorbing polarizer 58. The assembly is completed by a backlight 28 arranged below the liquid crystal cell 2.

[0082] refer to Fig.12 and Fig.13 The following part of the description relates to the case of a liquid crystal cell 32 provided with a reflective polarizing film 34, which includes an absorptive polarizer 36 combined with an at least partially reflective reflector 38. When the reflector 38 (preferably but not limited to a metal reflector) is only partially reflective (has only partial reflectivity), the liquid crystal cell 32 is semi-transmissive and semi-reflective, and the backlight device 28 is arranged below the reflective polarizing film 34. The relief structure of the assembly formed by the reflective polarizing film 34 and its reflector 38 can be obtained by hot forming or cold deformation against a mold having a concave-convex shape corresponding to the shape desired to be imprinted on the reflective polarizing film 34 under the same conditions as described above with reference to the assembly formed by the reflective polarizer 24 and the black or colored background layer 26. Once the reflective polarizing film 34 is shaped, a transparent leveling layer 42 composed of a photopolymerizable resin sensitive to ultraviolet radiation, for example, is deposited in the cavity of the absorptive polarizer 36. An optically clear adhesive layer 44 is deposited on the transparent planarization layer 42 either before or after the transparent planarization layer 42 is polymerized, by which the reflective polarizing film 34 is secured to the underside 22 of the rear substrate 8 .

[0083] Fig.14 6 is a view of a watch 60 equipped with a liquid crystal cell, wherein the reflective polarizing film arranged below the liquid crystal display device has been formed into a relief structure to display a relief graphic image 62 through the effective display surface of the liquid crystal cell. It can be seen that the effective information 64 displayed by the liquid crystal display device is permanently or on demand superimposed on the graphic image 62 formed in the reflective polarizing film, which gives the watch 60 a very eye-catching and creative aesthetic appearance. Obviously, the reflective polarizing film can be shaped not to display a graphic image, but to display technical information, such as a scale that matches the information displayed by the liquid crystal display device.

[0084] It goes without saying that the present invention is not limited to the embodiment of the reflective or semi-transmissive and semi-reflective liquid crystal display device just described, and various modifications and simple variations can be envisaged by those skilled in the art without departing from the scope of the invention defined by the attached claims. It should be particularly emphasized that a "reflective polarizer" refers to a polarizer that reflects light (component) of a polarization direction and transmits light (component) orthogonal to the polarization direction. Similarly, an "absorptive polarizer" refers to a polarizer that absorbs one component of light and transmits another component of light orthogonal to the absorbed light component. It will also be noted that the present invention is applicable to reflective or transmissive liquid crystal cells, whose liquid crystal molecules are arranged in a planar manner, that is, their long axis extends parallel to the liquid crystal cell substrate, or whose liquid crystal molecules are arranged vertically, that is, their long axis extends perpendicular to the liquid crystal cell substrate. Examples of such liquid crystal cells include twisted nematic, super twisted nematic, guest-host or vertically arranged or electrically controlled birefringent liquid crystal cells.

[0085] Reference numerals list

[0086] 1. Liquid crystal display device

[0087] 2. Liquid crystal unit

[0088] 4. Front base plate

[0089] 6. Observer

[0090] 8. Rear substrate

[0091] 10. Sealed frame

[0092] 12. Sealed housing

[0093] 14. Electrodes

[0094] 16. Counter electrode

[0095] 18. Reflective polarizing film

[0096] 20. Light

[0097] 22. Lower side

[0098] 24. Reflective Polarizer

[0099] 25. Adhesive layer

[0100] 26. Background layer

[0101] 27. Adhesive layer

[0102] 28. Backlight device

[0103] 29. Absorption polarizer

[0104] 30. Liquid crystal display device

[0105] 31. Upper surface

[0106] 32. Liquid crystal unit

[0107] 33. Adhesive layer

[0108] 34. Reflective polarizing film

[0109] 36. Absorption polarizer

[0110] 38. Reflector

[0111] 40. Effective display surface

[0112] 42. Transparent leveling layer

[0113] 44. Adhesive layer

[0114] 46. ​​Back

[0115] 48. Upper surface

[0116] 50. Diffuse layer

[0117] 52. Adhesive layer

[0118] 54. Absorption polarizer

[0119] 56. Transparent leveling layer

[0120] 58. Absorption polarizer

[0121] 60. Watch

[0122] 62. Graphics

[0123] 64. Effective information

Claims

1. A method for manufacturing a liquid crystal display device (1), the liquid crystal display device comprising a reflective or semi-transmissive and semi-reflective liquid crystal unit (2), the liquid crystal molecules of the liquid crystal unit being arranged in a planar or vertical manner, the liquid crystal unit (2) comprising a transparent front substrate (4) located on the side of an observer (6) and a transparent rear substrate (8), the rear substrate (8) extending below the front substrate (4) parallel to the front substrate (4) and spaced a certain distance from the front substrate (4), the front substrate (4) and the rear substrate (8) being connected to each other by a sealing frame (10), the sealing frame (10) defining a sealing housing (12), the liquid crystal The composition is confined in the sealed housing (12), the front substrate (4) and the rear substrate (8) are coated with conductive transparent electrodes (14) and counter electrodes (16) on their opposite surfaces, and the optical properties of the liquid crystal composition are changed by applying an electric field at the intersection between the electrode (14) and the corresponding counter electrode (16). The liquid crystal display device (1) is provided with a reflective polarizing film (18) for absorbing a first component of light (20) entering the liquid crystal cell (2) through the front substrate (4) and reflecting a second component of the light (20) polarized in a direction orthogonal to the direction of the first component. The manufacturing method comprises the following steps: A reflective polarizing film (18) is formed into a relief structure to give it a decorative and / or functional shape, which is visible to an observer (6) through a front substrate (4) of a liquid crystal cell (2), and then the reflective polarizing film (18) is fixed to the underside (22) of a rear substrate (8), wherein the reflective polarizing film (18) includes a reflective polarizer (24) combined with an absorptive polarizer (54), and the absorptive polarizer is bonded to the back side (46) of the reflective polarizer (24), and the assembly consisting of both the reflective polarizer (24) and the absorptive polarizer (54) is simultaneously formed into the relief structure.

2. The manufacturing method according to claim 1, characterized in that: A reflective polarizing film (18) is formed into a relief structure by being pressed against a mold having a concave-convex shape corresponding to a shape desired to be imprinted on the reflective polarizing film (18).

3. The manufacturing method according to claim 2, characterized in that: A reflective polarizing film (18) is pressed against a mold having a concave-convex shape by generating a gas vacuum.

4. The manufacturing method according to claim 2 or 3, characterized in that: The reflective polarizing film (18) is heated while the reflective polarizing film (18) is pressed against the mold having the concavoconvex shape.

5. The manufacturing method according to claim 1, characterized in that: The reflective polarizing film (18) is formed into a convex structure by insert injection molding.

6. The manufacturing method according to claim 2 or 3, characterized in that: Once the reflective polarizing film (18) is formed into a convex structure, a transparent leveling layer (42) and an adhesive layer (44; 52) are successively deposited on the upper surface (48) of the reflective polarizing film (18), and the reflective polarizing film (18) is fixed to the liquid crystal cell (2) with the help of the adhesive layer (44; 52).

7. The manufacturing method according to claim 5, characterized in that: Immediately after the reflective polarizing film (18) is formed into a relief structure and a transparent leveling layer (42) is deposited, a liquid crystal cell (2) is applied onto the transparent leveling layer (42) and the transparent leveling layer (42) is cured.

8. The manufacturing method according to claim 6, characterized in that: The adhesive layer (44; 52) is formed from an optically clear adhesive in the form of a pressure sensitive film laminated to the transparent planarization layer (42) or dispensed as a liquid adhesive layer onto the transparent planarization layer (42).

9. The manufacturing method according to claim 8, characterized in that: The light-transmissive adhesive is partially diffusely reflective.

10. The manufacturing method according to claim 6, characterized in that: A transparent planarization layer (56) is deposited on the back side (46) of the reflective polarizing film (18).

11. The manufacturing method according to claim 10, characterized in that: The transparent planarization layer (42) deposited on the upper surface (48) of the reflective polarizing film (18) and / or the transparent planarization layer (56) deposited on the back surface (46) of the reflective polarizing film (18) are obtained by photopolymerizable resin.

12. The manufacturing method according to claim 11, characterized in that: A transparent planarization layer (42) deposited on the upper surface (48) of the reflective polarizing film (18) and / or a transparent planarization layer (56) deposited on the back surface (46) of the reflective polarizing film (18) is polymerized by ultraviolet radiation.

13. The manufacturing method according to any one of claims 1 to 3, characterized in that: Prior to forming the relief structure, the upper surface (48) of the reflective polarizing film (18) is provided with a diffusing layer (50) to produce at least partial diffuse reflection.

14. The manufacturing method according to any one of claims 1 to 3, characterized in that: A reflective polarizing film (18) includes a reflective polarizer (24) combined with an at least partially absorbing background layer (26) disposed on a back side (46) of the reflective polarizer (24).

15. The manufacturing method according to claim 14, characterized in that: The at least partially absorbing background layer (26) is black or colored.

16. The manufacturing method according to claim 15, characterized in that: The black or colored background layer (26) is an ink layer or a laminated film, which is applied to the back side (46) of the reflective polarizer (24) before the reflective polarizer (24) is formed so that the black or colored background layer (26) is formed simultaneously with the reflective polarizer (24), or is applied to the back side (46) of the reflective polarizer (24) after the reflective polarizer (24) is formed.

17. The manufacturing method according to claim 14, characterized in that: When the background layer (26) is partially absorptive, the backlight device (28) is arranged below the background layer (26).

18. The manufacturing method according to any one of claims 1 to 3, characterized in that: The reflective polarizing film (34) includes an absorbing polarizer (36) combined with an at least partially reflective reflector (38) disposed below the absorbing polarizer (36).

19. The manufacturing method according to claim 18, characterized in that: The reflector (38) is a metal reflector.

20. The manufacturing method according to claim 18, characterized in that: When the reflector (38) is partially reflective, the backlight (28) is disposed beneath the reflective polarizing film (34).

21. A liquid crystal display device (1), comprising a reflective or semi-transmissive and semi-reflective liquid crystal unit (2), wherein the liquid crystal molecules of the liquid crystal unit are arranged in a planar or vertical manner, wherein the liquid crystal unit (2) is formed by a transparent front substrate (4) located on the side of an observer (6) and a transparent rear substrate (8), wherein the rear substrate (8) extends below the front substrate (4) parallel to the front substrate and at a certain distance from the front substrate, wherein the front substrate (4) and the rear substrate (8) are connected to each other by a sealing frame (10), wherein the sealing frame (10) defines a sealing housing (12), wherein a liquid crystal composition is confined in the sealing housing, wherein the front substrate (4) and the rear substrate (8) are coated on their opposite surfaces with a coating. The liquid crystal display device (1) is provided with a conductive transparent electrode (14) and a counter electrode (16), and the optical properties of the liquid crystal composition are changed by applying an electric field at the intersection between the electrode (14) and the corresponding counter electrode (16), the liquid crystal display device (1) is provided with a reflective polarizing film (18) to absorb a first component of light entering the liquid crystal cell (2) through the front substrate (4) and reflect a second component of the light polarized in a direction orthogonal to the direction of the first component, the reflective polarizing film (14) has a decorative and / or functional convex portion, the convex portion is visible to an observer (6) through the front substrate (4) of the liquid crystal cell (2), and the reflective polarizing film (18) is fixed to the lower side (22) of the rear substrate (8), wherein The reflective polarizing film (18) includes a reflective polarizer (24) bonded to an absorptive polarizer (54) bonded to the back side (46) of the reflective polarizer (24), the assembly of the reflective polarizer (24) and the absorptive polarizer (54) forming a relief structure.

22. The liquid crystal display device according to claim 21, characterized in that: A reflective polarizing film (18) includes a reflective polarizer (24) combined with an at least partially absorbing background layer (26) disposed on a rear surface (46) of the reflective polarizer.

23. The liquid crystal display device according to claim 22, characterized in that: The at least partially absorbing background layer (26) is black or colored.

24. The liquid crystal display device according to claim 23, characterized in that: The black or colored background layer (26) is an ink layer or laminate film applied to the back side (46) of the reflective polarizer (24).

25. The liquid crystal display device according to claim 21, characterized in that: The reflective polarizing film (34) includes an absorbing polarizer (36) combined with an at least partially reflective reflector (38) disposed below the absorbing polarizer (36).

26. The liquid crystal display device according to claim 25, characterized in that: The reflector (38) is a metal reflector.

27. The liquid crystal display device according to claim 25, characterized in that: When the reflector (38) is partially reflective, the backlight (28) is arranged below the reflector.

28. A timer, comprising the liquid crystal display device according to any one of claims 21 to 27.

Images