CH716960A2 - Liquid crystal display device. - Google Patents

Abstract

An aspect of the present invention relates to a liquid crystal display device (18), the display device comprising: two opposite transparent substrates designated respectively front substrate (14) and rear substrate (26), the front substrate being the one arranged on the observer side, the front and rear substrates being provided on their internal faces with transparent structured electrodes (16, 24), the superposition of which defines pixels of switchable shape between two optical states, the electrodes being connected to a voltage source by the 'intermediary of a control circuit, forming a cell closed by a sealing frame to receive in the space delimited by the substrates and the sealing frame a liquid crystal composition; and a decorative pattern (28) in direct contact with the front substrate or the rear substrate. Such a display device can be integrated into a timepiece or jewelry piece, for example.

Description

Technical area

The invention relates to a liquid crystal display device, a dial assembly for a timepiece comprising a dial and such a display device. The invention also relates to a timepiece and / or jewelry piece comprising such a display device as well as a method of manufacturing such a liquid crystal display device.

Technological background

[0002] Liquid crystal display devices have been well known in the watchmaking field since the seventies. Back then, liquid crystal displays were used to show or hide different segments that together formed digits for p. ex. indicate the time.

Currently, the possibilities offered by liquid crystal displays have developed well. For example, a decoration printed on plastic film can be placed between the polarizers of the display. The display can selectively show different parts of the printed decoration. The transparent plastic film can receive a decoration digitally printed by inkjet. The inks in the image can be opaque or semi-transparent to achieve color filters. The film and its print are laminated by means of an optically transparent adhesive film on the back side of the liquid crystal cell. It is also possible to laminate the film and its printing on the front face of the liquid crystal cell. The adhesive film typically has a height of between 15 µm and 100 µm.

Another possibility is to decorate the front face of the upper polarizer with ink printing, most often by screen printing. Obviously, it is possible to decorate the rear face of the rear polarizer with ink printing, also most often by screen printing.

On the other hand, there are color matrix liquid crystal displays. These use color filters (red, green, blue and black) to filter the color of the pixels of the matrix (red, green or blue) or mask the areas between the pixels (with black). These color filters are generally placed on the inside face of the front substrate of the liquid crystal cell, under the transparent electrode. These filters are produced by digital printing or by application of photostructurable resins which are structured in a chemical bath by the photolithography process. Introducing the filters into the cell under the electrode adds a technological complication to the process in the sense that after having produced these multiple color filters, it is necessary to add a planarization layer on which the transparent electrode is deposited.

General description of the invention

A first aspect of the invention relates to a liquid crystal display device (LCD), the display device comprising: two opposite transparent substrates designated respectively front substrate and rear substrate, the front substrate being the one disposed side observer, the front and rear substrates being provided on their internal faces with transparent structured electrodes, the superposition of which defines a pixel of switchable shape between two optical states, the electrodes being connected to a voltage source via a circuit of control, forming a cell closed by a sealing frame to receive in the space delimited by the substrates and the sealing frame a liquid crystal composition. The device further comprises a decorative pattern in direct contact with the front substrate and / or the rear substrate

It will be appreciated that the fact of having direct contact between the decorative pattern and one of the substrates allows several advantages: A) The alignment of the decorative pattern with respect to the switchable shaped pixel of the liquid crystal display is better because the scenery and the shape pixel are closer. On the one hand, alignment can be achieved more easily (eg optically) with respect to the conductive tracks during the watch manufacturing process, before different optical films prevent precise visualization of the conductive tracks. B) On the other hand, parallax is reduced to the thickness of the substrate alone (e.g. when thin substrates, 50-300 µm thick, are used, parallax is very low and the resulting optical defects are not are not visible to the naked eye). C) Reduced parallax and precise alignment achieve a fine, high-detail image that harmonizes well with the pixel shape of the LCD. There is thus no crosstalk and the shape pixel can cover exactly the desired area of the scenery, regardless of the viewing angle, resulting in a high quality moving image. D) Because the decorative layer is in direct contact with the LCD substrate and without a backing film, it is closest to the reflector, allowing a high resolution image with very small apertures to reflect more light. The reflectivity of the image is thus improved, since light rays reflected at a large angle of incidence are less likely to be absorbed.

[0008] The transparent structured electrodes can be made of indium-tin oxide (ITO), or of indium-zinc oxide (IZO) or any other transparent electrode commonly used in the manufacture of electronic displays.

[0009] According to one embodiment, the liquid crystal cell may comprise one or more liquid crystal alignment layers arranged on the electrodes. Preferably, the one or more liquid crystal alignment layers impose a nematic liquid crystal mode arranged in a helix ("twisted nematic") or a nematic liquid crystal mode in a super helix ("super-twisted nematic"). ) liquid crystal in the liquid crystal cell. Other modes can be considered, such as the VA mode (for "vertical alignment") or the ECB mode (for "electrically controlled birefringence" or other variations deriving from the combination of the aforementioned modes).

The decorative pattern can be arranged on an outer surface of the front or rear substrates. Preferably, the decorative pattern is disposed on the outer surface of the back substrate.

According to a preferred embodiment, the decorative pattern is aligned with the structured electrodes.

The decorative pattern can be an image complementary to the shaped pixels defined by the electrodes.

The decorative pattern may be a digitally printed decorative pattern, optionally by inkjet, or comprise a structured ink layer. Digital printing refers to a process for printing a digital image on a substrate. Examples of digital printing methods include inkjet printing and laser printing. In inkjet printing processes, the image is formed by the projection of ink droplets onto the substrate. The ink can include pigments and / or dyes as colorants. The ink may or may not be photosensitive. The decorative pattern is preferably digitally printed by inkjet.

[0014] Alternatively or additionally, the decorative pattern may comprise one or more layers of structured photosensitive resins and / or one or more structured decorative thin layers (metallic, absorbent dielectric (eg: TiAION, WO, TiN ...) or dielectric mirror).

The set of layers forming the decorative pattern is carried directly by the front substrate or the rear substrate.

The front substrate and / or rear substrate may have a thickness in the range from 50 μm to 1 mm, preferably in the range from 80 μm to 0.5 mm.

According to one embodiment, the front substrate is associated with a front absorbent and transmissive polarizer. In addition, the rear substrate is associated with a reflective and absorbent rear polarizer. The decorative pattern is disposed between the rear substrate and the rear polarizer.

According to one embodiment, the front substrate is associated with a front absorbent and transmissive polarizer. In addition, the rear substrate is associated with a reflective and absorbent rear polarizer. The decorative pattern is disposed between the front substrate and the front polarizer.

According to one embodiment, the front substrate is associated with a front absorbent and transmissive polarizer. In addition, the rear substrate is associated with a reflector. The decorative pattern is disposed between the front substrate and the front polarizer.

The liquid crystal composition may include a dichroic dye. The rear substrate is then associated with a reflector. The decorative pattern can be disposed either on the outer surface of the front substrate or between the rear substrate and the reflector.

[0021] According to one embodiment, the liquid crystal composition comprises a dichroic dye. The front substrate is associated with a transmissive absorbent polarizer. The rear substrate is associated with a reflector. The decorative pattern can be arranged either between the front polarizer and the front substrate, or between the rear substrate and the reflector.

[0022] According to one embodiment, the liquid crystal composition comprises a dichroic dye. The rear substrate is associated with an absorbent reflective rear polarizer. The decorative pattern can be disposed between the rear polarizer and the rear substrate.

The display can be reflective, emissive or transflective. By transflective display is meant a hybrid reflective and transmissive display. The display is transmissive in the sense that a backlight is arranged behind the rear substrate. The display is also reflective in the sense that incident ambient light is reflected by a semi-reflective, semi-transparent reflector behind the back substrate. In the case of a transflective display, the semi-reflective and semi-transparent reflector will combine the property of reflecting ambient light while allowing light from the backlight to be transmitted.

The rear polarizer can be replaced by a transflective polarizer. A backlighting device may be disposed at the rear of the transflective polarizer.

The rear polarizer can be replaced by a transparent absorbent polarizer. A backlighting device may be disposed at the rear of the transflective polarizer.

According to a particular embodiment of the invention the decorative pattern is in direct contact with the front substrate and with the rear substrate and in which the decorative pattern is made in at least two complementary pattern portions one of the the other is the juxtaposition of the two complementary pattern portions forming said decorative pattern.

A second aspect of the invention relates to a piece of timepiece and / or jewelry (eg a watch) and / or a piece of portable electronics (eg smart sportswear, portable measuring instruments, etc. etc ...) and / or non-portable (eg home automation) comprising a liquid crystal display device as described above.

A third aspect of the invention relates to a method of manufacturing a liquid crystal display device. The method comprises: providing a front substrate and a rear substrate, the front and rear substrates being provided on their internal faces with transparent structured electrodes, the superposition of which defines pixels of switchable shape between two optical states ; the provision of a seal frame on the internal face of one of the two substrates; o sealing the two substrates together to define a space delimited by the substrates; o filling the space delimited by the substrates with a liquid crystal composition; and the application of a decorative pattern in direct contact with the front substrate or the rear substrate.

The application of the decorative pattern can comprise: o either digital printing of the decorative pattern, preferably by inkjet, o or the application and structuring, preferably by photolithography, of a photosensitive resin, o or the physical or chemical vapor deposition of a thin metallic and / or dielectric layer (typically less than 10 microns and preferably less than 1 micron) and the structuring of the deposited thin layer, preferably by photolithography, or a combination of these methods of applications.

The combination of these application methods can allow the application of several decorative layers in order to achieve more complex decorations with different degrees of resolution or fineness.

[0031] According to yet another aspect, the invention relates to a dial assembly for a timepiece comprising a dial and a liquid crystal display device, the display device comprising: two opposite transparent substrates designated respectively front substrate and rear substrate, the front substrate being that arranged on the observer side, the front and rear substrates being provided on their internal faces with transparent structured electrodes, the superposition of which defines pixels of switchable shape between two optical states, the electrodes being connected to a source voltage through a control circuit, forming a cell closed by a sealing frame to receive in the space delimited by the substrates and the sealing frame a liquid crystal composition; and a decorative pattern in direct contact with the front substrate and / or with the rear substrate, said dial bearing a static image complementary to that of the decorative pattern of the display device. We could thus have, for example, the dial which forms the sky with fixed stars, and the decorative motif could represent certain planets, comets or other celestial objects (natural satellites or not) which will be represented by the liquid crystal display device. dynamically.

Brief description of the drawings

Other features and characteristics of the invention will emerge from the detailed description of certain advantageous embodiments presented below, by way of illustration, with reference to the accompanying drawings which show: Fig.1: a view in section of a liquid crystal display device of a watch according to one embodiment of the invention; Fig.2: a top view of an electrode for a liquid crystal display of a watch according to one embodiment of the invention; Fig.3: a sectional view of a liquid crystal display device of a watch according to one embodiment of the invention; and Fig.4: a front view of a dial assembly for a timepiece comprising a dial and a liquid crystal display device according to the invention.

Detailed description of several embodiments of the invention

[0033] FIG. 1 illustrates a reflective liquid crystal display device 10 of a watch according to one embodiment of the invention. The display device 10 comprises an absorbing and transmissive front polarizer 12 (absorbing for light polarization and transmissive for orthogonal polarization), a transparent front substrate 14, a structured transparent front electrode 16, a front alignment layer 18. , a liquid crystal composition 20, a back alignment layer 22, a structured transparent back electrode 24, a back substrate 26, a decorative pattern 28, a reflective and transmissive back polarizer 30 and a black background 32 (or, according to a other embodiment, colored). Alternatively, the rear polarizer 30 can be an absorbing and transmissive polarizer associated with a reflector. The display device 10 is reflective in the sense that the incident surrounding light 34 is used as a light source for the display. Incident surrounding light 34 passes through the various layers of display device 10 in the order listed above, is reflected on rear polarizer 30, and returns to the user's eye. The superposition of the structured electrodes 16, 24 defines a set of shaped pixels switchable between two optical states. The electrodes 16, 24 are connected to a voltage source (not shown) via a control circuit (not shown). The application of a voltage (or the absence of application) makes it possible to perform a switching between the two optical states of the liquid crystals 20.

The front substrate 14 and the rear substrate 26 can be made of glass or plastic. The substrates 14, 26 are oppositely arranged to create a liquid crystal cell 36 between the front substrate and the rear substrate. The liquid crystal cell 36 which includes the front electrode 16, the front alignment layer 18, the liquid crystal composition 20, the rear alignment layer 22 and the rear electrode 24. The alignment layers 18, 22 causes the liquid crystal 20 to assume a helical configuration when no electric field is applied by the electrodes 16, 24. The alignment layers 18, 22 may be, e.g. eg, polyimide. Depending on the orientation of the polarizers 12, 30, the display device 10 can operate in a "normally white" mode, that is to say a mode in which light is reflected when no electric field is applied to the liquid crystal, or in "normally black" mode, that is to say a mode in which light is not reflected when no electric field is applied to liquid crystals. The other optical state is reached when an electric field is applied between the electrodes 16, 24.

The liquid crystals 20 of the display device 10 are arranged in several units (also called shaped pixels), defined by the structured electrodes 16, 24, independently switchable in the sense that the optical state of a first pixel shape does not affect the optical state of a second shape pixel directly adjacent to the first shape pixel. The different shaped pixels are switched thanks to a voltage delivered by the structured electrodes 16, 24. Fig. 2 illustrates a possible structuring of the electrodes 16, 24. Pixels of shape 38i (in black in FIG. 2) in the shape of crescents are defined in order to be able to selectively switch the state of the liquid crystals situated at the level of pixels of shape 38i. , between the front electrode 16 and the rear electrode 24. A switching shape pixel 38i may cover one or more elements of the decorative layer. These elements can be continuous parts of the decorative pattern and / or pixels forming said decorative pattern in the case of a high resolution image. The shape pixels can be arranged regularly (eg for raster displays) or not. The shape of the shape pixels is not limited. As indicated above, they may have eg a crescent shape, or more simply a rectangular or square shape when viewed from above the display.

The front substrate 14 and / or the rear substrate 26 have a thickness comprised in the range ranging from 50 μm to 1 mm, preferably in the range ranging from 80 μm to 0.5 mm. According to a first embodiment, the decorative pattern 28 is digitally inkjet printed directly onto the outer surface of the rear substrate 26. The pattern may include absorbent areas and transparent areas allowing light to (partially) pass through. through the decorative pattern to reach the rear polarizer 30.

It will be appreciated that the fact of printing the decorative layer directly on the substrate 26 mitigates several drawbacks of the solutions proposed by the prior art. In particular, the alignment between the elements of the decorative pattern and the switching segments 38 is more precise. Alignment can generally be achieved with an accuracy of 5 µm or less, as the decorative pattern 28 is very close to the switching segments 38 defined by the structured electrodes 16,24 compared to prior art solutions. This has the consequence that the switching segments 38i cover exactly the desired areas of the decorative pattern, regardless of the viewing angle of the display device. By "exactly" it is understood that the offset is less than 5 µm and therefore will not be visible to the naked eye by the user. The aesthetic will appear flawless. On the other hand, alignment can be performed optically with respect to the switching segments 38 during the manufacture of the display, before other layers prevent viewing of the electrodes, in particular the structure of the electrodes. It should also be noted that the parallax is reduced to the sole thickness of the substrate. The use of thin substrates (50 to 300 µm) makes it possible to reduce parallax so that the resulting optical defects are not perceptible to the naked eye. In addition, even though the decorative pattern 28 includes very small transparent openings, more light can be reflected because the decorative pattern 28 is directly below the substrate and without a backing film between the decorative layer and the back polarizer 30. The rays Light reflected at a large angle of incidence is then less likely to be absorbed. The reflectivity (and therefore the visibility) of the decorative pattern 28 is thus improved compared to the prior art.

According to a second embodiment of the invention, the decorative pattern 28 can be applied to the outer surface of the front substrate 14 instead of being applied to the outer surface of the rear substrate 26 (see first embodiment) . It is obviously possible to combine the first and the second embodiment in order to obtain a display device comprising two decorative patterns.

According to a third embodiment of the invention, one or more photo-structurable resins can be deposited and structured by photolithography on the outer surface of the front substrate 14 and / or on the outer surface of the rear substrate 26. The resins can be colored or black and be arranged to form a decorative pattern 28 after deposition.

[0040] According to a fourth embodiment of the invention, the decorative pattern 28 may be a thin metallic layer (eg, an aluminum layer, a gold layer, a silver layer, a layer of chromium) and / or dielectric (eg a layer of colored oxy-nitrides) deposited by physical or chemical vapor deposition. The decorative motif 28 can be structured, in particular by photolithography-etching. It is also possible to perform deposition and structuring in a single step by deposition through a mask.

It should be noted that it is possible to combine the decorative patterns 28 described above in order to produce a decorative pattern 28 on the outer surface of the front substrate and / or on the outer surface of the rear substrate comprising a decorative pattern carried out as indicated above.

According to other embodiments, other arrangements of polarizers and decorative pattern can be contemplated. For example, the front substrate can be associated with an absorbing and transmissive front polarizer and the rear substrate can be associated with a reflector. The decorative pattern is disposed between the front substrate and the front polarizer.

The liquid crystal composition can include a dichroic dye. In this case, different arrangements can also be contemplated. According to a first example, the rear substrate is associated with a reflector. The decorative pattern can then be arranged either on the outer surface of the front substrate or between the rear substrate and the reflector. According to a second example, the front substrate is associated with a transmissive absorbing polarizer and the rear substrate is associated with a reflector. The decorative pattern can then be arranged either between the front polarizer and the front substrate or between the rear substrate and the reflector. According to a third example, the rear substrate is associated with an absorbent reflective rear polarizer. The decorative pattern can then be placed between the rear polarizer and the rear substrate.

According to one embodiment of the invention, the display device 10 can be transflective. In this case, the display device 10 comprises a backlight 40 arranged behind a semi-transparent black background 32 (see Fig. 3). In another embodiment, the semi-transparent black background 32 could be replaced by an absorbent / transparent polarizer. In another embodiment of a transflective display device, the rear polarizer 30 could be replaced by a reflective / transmissive polarizer partially effective in its reflective function, and the darkfield 32 would be replaced by an absorbent / transmissive polarizer or a semi-reflective background. -absorbent. In another embodiment, the rear polarizer assembly 30 and the black field 32 would be replaced by a transflective polarizer. The backlight emits light 42 and may include one or more inorganic light emitting diodes and / or one or more organic light emitting diodes.

According to one embodiment of the invention, the display device 10 can be transmissive. In this case, the display device 10 comprises a backlight 40 arranged at the rear of a display device characterized in that the rear polarizer 30 is an absorbing / transmissive polarizer and that there is no longer any black background.

An example of application of such a display device in watchmaking or jewelry consists of the production of a moon phase by the combination of a high resolution decorative pattern of the moon with a cell liquid crystal whose electrode segments are arranged to form a multitude of crescents (see Fig. 2) which, aligned with the decorative pattern of the moon, make it possible to display the evolution of the phases of the moon. The liquid crystal display device is used to hide the parts of the moon which are currently hidden by the Earth's shadow. It is also possible that the electrodes include other segments to display additional information such as time, date, day, weather, barometric, altimetric information or to animate decorative or playful elements such as twinkling stars in the starry sky around the moon. It should be noted that the present invention also has an interest in sportswear type products.

One can also consider according to a variant of the invention to do the same with an eclipse of the sun or of the moon, the pattern being an image of a star and the display device comprising a plurality of switchable shaped pixels. defined by transparent structured electrodes and representing shaped segments capable of representing a moving image of said star in order to represent said eclipse. Of course, other celestial objects such as comets, natural satellites or not can be represented in a similar manner on the display in a dynamic manner.

It will be noted that when the device is combined with a transflector at the rear, the associated backlighting device can emit an adjustable color to better match the reality of the colors of the object of the pattern to be represented, in particular during partial eclipses or total.

In Figure 4 is shown a dial assembly 44 for a timepiece (not shown) comprising a dial 46 and a liquid crystal display device 48 of the type described in connection with Figures 1 to 3 The display device 48 is visible through a window 50 provided in the dial 46. In the illustrated example, the dial 46 comprises a still image which forms the sky with fixed stars 52, and the decorative pattern of the display. represents a moon in the form of several pixels of form 38i as described previously in connection with FIG. 2, said pattern possibly representing the evolution of the phases of the moon dynamically. Alternatively, the decorative pattern could represent, in the form of a set of shaped pixels, certain planets, comets or other celestial objects (natural satellites or not) which will be represented by the liquid crystal display device in a dynamic manner.

While particular embodiments have just been described in detail, those skilled in the art will appreciate that various modifications and alternatives to these may be developed in light of the overall teaching provided by the present disclosure of invention. Therefore, the specific arrangements and / or methods described herein are intended to be given by way of illustration only, without the intention of limiting the scope of the invention, which is determined by the scope of the appended claims.

Claims (22)

1. A liquid crystal display device, the display device comprising: two opposite transparent substrates designated respectively front substrate and rear substrate, the front substrate being that arranged on the observer side, the front and rear substrates being provided on their internal faces with transparent structured electrodes whose superposition defines pixels of switchable shape between two states optical, the electrodes being connected to a voltage source via a control circuit, forming a cell closed by a sealing frame to receive in the space delimited by the substrates and the sealing frame a composition of crystals liquids; and a decorative pattern in direct contact with the front substrate and / or with the rear substrate. 2. Display device according to claim 1 characterized in that the decorative pattern is disposed on an outer surface of the front or rear substrates. 3. Display device according to claim 1 or 2, characterized in that the decorative pattern is disposed on the outer surface of the rear substrate. 4. Display device according to any one of the preceding claims characterized in that the decorative pattern is aligned with the structured electrodes. 5. Display device according to claim 4, characterized in that the decorative pattern is an image complementary to the shaped pixels defined by the electrodes. 6. Display device according to any one of the preceding claims, characterized in that the decorative pattern comprises at least one structured ink layer, photosensitive or not, at least one structured thin metallic or structured dielectric layer, or a combination of these different layers, all of these decorative layers being carried directly by the front substrate or the rear substrate. 7. A display device according to any one of claims 1 to 6, wherein the front substrate is associated with an absorbing and transmissive front polarizer and wherein the rear substrate is associated with a reflective and absorbing rear polarizer, and wherein the decorative pattern is disposed between the rear substrate and the rear polarizer. 8. A display device according to any one of claims 1 to 6, wherein the front substrate is associated with an absorbing and transmissive front polarizer and wherein the rear substrate is associated with a reflective and absorbing rear polarizer, and wherein the decorative pattern is disposed between the front substrate and the front polarizer. 9. A display device according to any one of claims 1 to 6, wherein the front substrate is associated with an absorbing and transmissive front polarizer and wherein the rear substrate is associated with a reflector and wherein the decorative pattern is arranged. between the front substrate and the front polarizer. 10. A display device according to any one of claims 1 to 6, wherein the liquid crystal composition comprises a dichroic dye and wherein the rear substrate is associated with a reflector and wherein the decorative pattern is disposed either on the back. outer surface of the front substrate is between the rear substrate and the reflector. 11. A display device according to any one of claims 1 to 6, wherein the liquid crystal composition comprises a dichroic dye, wherein the front substrate is associated with a transmissive absorbent polarizer and wherein the rear substrate is associated with. a reflector and in which the decorative pattern is disposed either between the front polarizer and the front substrate or between the rear substrate and the reflector. A display device according to any one of claims 1 to 6, wherein the liquid crystal composition comprises a dichroic dye, wherein the rear substrate is associated with an absorbent reflective rear polarizer and wherein the decorative pattern is disposed. between the rear polarizer and the rear substrate. 13. A display device according to any one of claims 7, 8 or 12, in which the rear polarizer is replaced by a transflective polarizer and in which a backlighting device is arranged at the rear of the transflective polarizer. 14. A display device according to any one of claims 7, 8 or 12, wherein the rear polarizer is replaced by a transmissive absorbent polarizer and wherein a backlighting device is disposed at the rear of the transflective polarizer. 15. A display device according to claim 13 or 14 wherein the backlighting device emits a light whose color is adjustable. 16. A display device according to any one of claims wherein the decorative pattern is in direct contact with the front substrate and with the rear substrate and wherein the decorative pattern is made in at least two complementary pattern portions one. on the other, the juxtaposition of the two complementary pattern portions forming said decorative pattern. 17. A dial assembly for a timepiece comprising a dial and a display device according to any one of claims 1 to 16, said dial bearing a static image complementary to that of the decorative pattern of the display device. 18. Timepiece and / or jewelry comprising a display device according to any one of the preceding claims. 19. Timepiece and / or jewelry according to claim 18, characterized in that the pattern is an image of a star, the display device comprising a plurality of switchable shaped pixels defined by the transparent structured electrodes and representing shaped segments capable of representing an animated image of said star. 20. Timepiece and / or jewelry according to claim 19, characterized in that the star is the moon and in that the plurality of switchable shaped pixels defined by the transparent structured electrodes and represent segments in the form of. crescents representing the phases of the moon. 21. A method of manufacturing a liquid crystal display device, the method comprising: the provision of a front substrate and a rear substrate, the front and rear substrates being provided on their internal faces with transparent structured electrodes, the superposition of which defines pixels of shape switchable between two optical states; the provision of a frame of seals on the internal face of one of the two substrates; sealing the two substrates together to define a space delimited by the substrates; filling the space delimited by the substrates with a liquid crystal composition; and applying a decorative pattern in direct contact with the front substrate or the rear substrate. 22. The manufacturing method according to claim 20, wherein the application of the decorative pattern comprises: o either digital printing of the decorative motif, preferably by inkjet, o either the application and structuring, preferably by photolithography, of a photosensitive resin, o either the physical or chemical vapor deposition of a thin metallic and / or dielectric layer and the structuring of the deposited layer, preferably by photolithography, or a combination of these application methods.