Liquid crystal device for a timepiece

Abstract

To visually distinguish switchable information or decoration and to perform this without increasing the thickness of an LCD cell, with less complexity and without taking up space.SOLUTION: The display device comprises a liquid crystal cell (2) formed from two transparent plates (4, 6), defines a useful zone (12) so as to define a visible zone of the liquid crystal cell, and incorporates electrodes forming a switchable display of an item of information and / or of a decoration. The liquid crystal cell comprises, in the useful zone, a plurality of polarisers 16, 18 arranged in a plurality of distinct zones 17, 19, respectively, on the external face 5 of one of the two transparent plates, each partially forming a switchable display. The two polarizers have different optical properties or different polarization directions between them and are configured to visually create a difference between the respective portions of the two polarizers and / or the respective portions of the switchable display in the respective discrete zones.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to the field of manufacturing liquid crystal display devices (hereinafter also referred to as "LCD devices") for watches, and more generally to the field of manufacturing liquid crystal cells (hereinafter also referred to as "LCD cells") forming such LCD devices. [Background technology]

[0002] Patent Document 1 describes an electronic display assembly with a contrast inversion function. The electronic display assembly is formed from a liquid crystal display cell having electrodes and counter electrodes that define switchable information segments so that the contrast of the entire useful zone of the display cell can be continuously changed, and a light valve formed by a liquid crystal cell having electrodes and counter electrodes that overlap the display cell and cover the entire useful zone of the display cell. Alternatively, the electronic display assembly is formed from at least two electrodes and two corresponding counter electrodes that define at least two display zones complementary to the useful zone, which can simultaneously present positive contrast (dark information on a light background) and negative contrast (bright information on a dark background), respectively. The display cell and light valve are equipped with a first front polarizer and a second rear polarizer. The term "useful zone" of the display cell or electronic display assembly is understood to mean the zone designed to be viewed by the user, in other words, the visible zone of the display cell or electronic display assembly after it is incorporated into a watch.

[0003] The '2006 patent provides similar teachings to the previous patent, but is more sophisticated in that it provides a display assembly with a color contrast inversion function designed to invert the color of the information displayed or the background on which this information is displayed when the electrodes of the display cell are activated (ON state). An intermediate polarizer located between the display cell and the light valve is also provided for this purpose. To enable contrast inversion or to distinguish various display zones within a display assembly by changing the color of their respective backgrounds, the aforementioned display assemblies are complex and cumbersome. They are formed from two liquid crystal cells stacked on top of each other. However, it should be noted that being able to distinguish display zones by the color (including white and black) of the background and / or the shade of this color, particularly the lightness and darkness, and / or the color of the displayed information can be useful for emphasizing or highlighting portions of information. In particular, this provides a visual contrast between different display zones. Thus, the separation of various display zones in an LCD display assembly provides an interesting aesthetic aspect in addition to a functional aspect, for example, by visually separating a time display zone from a date display zone or selected function. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent No. 1128240 [Patent Document 2] European Patent No. 1156360 Summary of the Invention [Problem to be solved by the invention]

[0005] The main object of the present invention is to provide a liquid crystal display device (LCD device) comprising an LCD cell for switchable display of at least one information item and / or at least one decoration, defining various zones in the useful zone of the LCD cell, at least two of which can be used for switchable display, with a visual variation between them, in particular a color difference (including white and black) between said at least two zones and / or a difference in shade of at least one color (lighter or darker) and / or a different optical effect and / or color difference in the switchable display provided in these at least two zones. The present invention therefore aims to visually distinguish said at least two zones in the useful zone of an LCD cell in an LCD display device and / or to visually distinguish switchable information or decoration in these at least two zones, in particular without increasing the thickness of a conventional LCD cell forming such an LCD display device, and with relatively little complexity and little space. [Means for solving the problem]

[0006] To this end, the present invention provides a watch display device comprising a liquid crystal cell formed from transparent first and second plates and a bead of adhesive bonding the first and second plates together and defining, together with the first and second plates, a closed space containing liquid crystals. The liquid crystal cell defines, inside the bead of adhesive, a useful zone intended to define the visible zone of the liquid crystal cell in a watch for which the display device is designed, and incorporates electrodes (hereinafter including "electrodes" and "counter electrodes") that form a switchable display of at least one information item and / or at least one decoration in the useful zone. The liquid crystal cell comprises a plurality of polarizers in the useful zone, the polarizers being arranged in a plurality of distinct zones on the outer surface of the first plate, each of which partially forms the switchable display. At least two of the plurality of polarizers have at least one different optical property or different polarization direction between them, and the watch display device is configured to visually generate a difference between at least respective portions of the at least two polarizers and / or between respective portions within each distinct zone of the switchable display.

[0007] The present invention has the advantage of achieving its primary objectives using a single LCD cell without the need for an additional light valve overlaying the LCD cell. In other words, the watch display device of the present invention can comprise only one base assembly formed by two transparent plates joined by a bead of adhesive and defining a space between them containing liquid crystal. Therefore, the display takes up very little space, does not increase the thickness of the LCD display device used in the watch, and is relatively simple.

[0008] In a typical embodiment, the at least two polarizers of the plurality of polarizers extend in substantially the same geometric plane.

[0009] In a first variant of the general embodiment, the at least two polarizers of the plurality of polarizers are juxtaposed and have respective contours, with a portion of one contour running alongside a portion of the other.

[0010] In a second variant of the general embodiment, a first polarizer of the at least two polarizers of the plurality of polarizers has an opening in which a second polarizer of the at least two polarizers is disposed, and the second polarizer has an outer contour that extends along the contour of the opening.

[0011] The typical embodiment has the advantage of taking up very little space as it does not increase the thickness of the conventional LCD cells that form the LCD watch display device. [Brief explanation of the drawings]

[0012] The invention will now be explained in more detail with reference to the accompanying drawings, given as non-limiting examples, in which: [Figure 1] 3 is a cross-sectional view along section line II in FIG. 2 of an LCD cell forming a first variant of the first main embodiment of the watch display device according to the present invention. [Figure 2] FIG. 2 is a top view of the watch display device shown in FIG. [Figure 3] FIG. 10 is a cross-sectional view of an LCD cell forming a second variant of the first main embodiment. [Figure 4] FIG. 6 is a cross-sectional view along line IV-IV in FIG. 5 of an LCD cell forming a third variant of the first main embodiment. [Figure 5] FIG. 5 is a top view of the watch display device shown in FIG. 4. [Figure 6] 2 is a cross-sectional view, similar to FIG. 1, of an LCD cell forming a first variant of the second main embodiment of the watch display device according to the invention; [Figure 7] FIG. 10 is a cross-sectional view of an LCD cell forming a second variant of the second main embodiment. [Figure 8]FIG. 10 is a cross-sectional view of an LCD cell forming a third variant of the second main embodiment. [Figure 9] 1 is a top view of a particular variation of a watch display device according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0013] 1 and 2, an LCD cell 2 forming a first variant of the first main embodiment of the watch display device according to the invention will be described.

[0014] The watch display device generally comprises a liquid crystal cell 2 formed from a first transparent plate 4, a second transparent plate 6, and a bead of adhesive 8 joining the first and second plates and defining a closed space containing liquid crystals 10. The liquid crystal cell defines a useful zone 12 inside the bead of adhesive, which useful zone 12 is intended to define the visible zone of this cell in a watch for which the display device is designed, and the liquid crystal cell incorporates two sets of electrodes 34 and 36 on the inner surface of the first transparent plate 4 and two sets of electrodes 35 and 37 on the inner surface of the second transparent plate 6, the two sets of electrodes 35 and 37 being arranged opposite the two sets of electrodes 34 and 36, respectively, and at least partially overlapping these electrodes to form a switchable display 30 of at least one item of information and / or at least one decoration in the useful zone. It should be noted that a "set of electrodes" is generally understood to mean "at least one electrode," and the reference numerals may refer to either a set of electrodes or one or more electrodes within the set. In the example shown in Figure 2, each set of electrodes comprises a plurality of electrodes that define segments for the display of the conventional digits "0" through "9" in an LCD clock display (each set of electrodes is represented in the figure by solid lines to simplify the drawing).

[0015] According to the invention, the liquid crystal cell 2 comprises a plurality of polarizers in the useful zone 12, more particularly two sets of polarizers 16 and 18 in the example shown, which are arranged in a plurality of distinct zones on the outer surface 5 of the first plate 4, namely in two distinct zones 17 and 19 in the example shown. Each of the electrodes 34 to 37 overlaps a polarizer 16, 18 of the plurality of polarizers and a polarizer 20 arranged on the outer surface 7 of the second transparent plate 6, in such a way that together they form a switchable display 30. Also, generally speaking, at least two of the polarizers (i.e. the two polarizers 16, 18 in the variant shown) each overlap at least one pair of electrodes 34 and 35, 36 and 37, respectively, which are arranged to form a portion 30A, 30B of the switchable display 30 in each distinct zone 17, 19 through which the polarizer extends. It should be noted that in the illustrated example, each of the two polarizers 16, 18 overlaps at least one pair of electrodes such that each distinct zone of the polarizer forms part of the switchable display 30. In other words, each polarizer in the plurality of polarizers forms part of the switchable display 30.

[0016] Generally speaking, the at least two polarizers of the plurality of polarizers have at least one different optical property or different polarization direction between them, and the LCD cell is arranged to produce a visual difference between at least respective portions of the at least two polarizers and / or respective portions of the switchable display in each of the at least two respective distinct zones in the watch display device. In the illustrated example, the two polarizers 16 and 18 have a visual difference between them in the display device, particularly in the LCD cell 2, i.e., in combination with the polarizer 20 arranged oppositely on the outer surface of the second plate 6. Also, portions 30A, B of the switchable display 30 in each distinct zone 17, 19 visually indicate a change when these portions of the switchable display are activated.

[0017] 1 and 2, polarizers 16 and 18 are preferably rear polarizers located beneath plate 4, the lower plate, and polarizer 20 is a front polarizer, the only polarizer, located advantageously on the outer surface 7 of second plate 6, the upper plate. Preferably, as shown, single polarizer 20 extends across the entire useful surface 12 of LCD cell 2, advantageously slightly around the periphery of this useful surface. It should be noted that in a particular variant, LCD cell 2 is reversed in its orientation in the watch, so that polarizers 16 and 18 are front polarizers and polarizer 20 is the rear polarizer. This particular variant is not preferred in view of the aesthetic advantages of a unitary front polarizer spanning the entire useful surface 12, since gaps between rear polarizers are less visible to the user of the watch than the same gaps between front polarizers.

[0018] Specifically, the three polarizers 16, 18, and 20 are identical in material and absorbing and transmissive. In a watch, the LCD display device is placed above a transparent dial, particularly an analog display that can be at least partially viewed through the LCD display device, and has a color different from that of the polarizers. However, the polarizer 16 has a polarization direction that is orthogonal to the polarization directions of the polarizers 18 and 20 in the LCD cell 2, and the polarizers 18 and 20 have the same polarization direction. Because the LCD cell in this case is a TN type, the separate zone 17 has a relatively light background (corresponding to the color of the dial), the analog display portion 30A has positive contrast, and overlapping activated electrode pairs produce relatively dark segments. Meanwhile, the separate zone 19 has a relatively dark background, the analog display portion 30B has negative contrast, and overlapping activated electrode pairs produce relatively light segments (corresponding to the color of the dial). In this way, the zone 17 within the useful zone 12 always allows the viewer to see what is underneath through the LCD display device, particularly the analog display and dial; only the activated segments of the switchable display obscure this background. In contrast, zone 19 within useful zone 12 allows the background to be seen only through activated segments of the switchable display. It should be noted that, as in the other variants described below, polarizer 18 is advantageously covered at its rear face with a reflective film to enhance contrast. In another configuration of the watch, the LCD cell is arranged as the dial of an analog display, i.e., beneath the hands of this analog display. While the configuration of the LCD display device according to the invention is advantageously incorporated into watches with analog displays, the display device according to the invention can also be incorporated into electronic watches without analog displays.

[0019] In a first general variant, the different optical property between the two polarizers is a difference in color.

[0020] In a second general variant, the different optical property between the two polarizers is a difference in shade of a given color, i.e. a difference in lightness.

[0021] According to an important feature of the main embodiment, the at least two polarizers of the plurality of polarizers extend substantially in the same geometric plane, preferably in the same geometric plane 40. More generally, all polarizers in the plurality of polarizers extend substantially in the same geometric plane, preferably all in the same geometric plane 40.

[0022] According to a specific feature of the present invention, a first polarizer of at least two of the plurality of polarizers has an opening in which a second polarizer of the at least two of the plurality of polarizers is disposed, the second polarizer having an outer contour that extends along the contour of the opening. In the first variant described in this case, the polarizer 16 has an opening 14 in which the polarizer 18 is disposed, the dimensions of the polarizer 18 corresponding to the dimensions of the opening. Thus, the outer contour of the polarizer 18 extends along the contour of the opening 14. The term "extend" is understood to have a standard dictionary definition, i.e., "extend close to, in particular parallel to, the opening." The gap between the two contours that extend alongside each other is minimal and is intended to be barely visible, or preferably invisible to the user. In a major embodiment, the first and second polarizers are disposed in substantially the same geometric plane, preferably in the same geometric plane, so that the polarizer 18 is disposed inside the opening 14 of the polarizer 16. To ensure that any gaps are minimal and preferably invisible, specific manufacturing methods are required to position polarizer 16 very accurately relative to polarizer 18. To this end, target / guide marks can be provided on at least one of the two transparent plates 4 and 6 above and below the bead of adhesive 8, such as that shown in Figure 1, with the target / guide marks outside of useful zone 12. These target / guide marks allow for precise alignment of the polarizer with the alignment marks in a fixed, defined relationship when the polarizer is placed on the outer surface of the final transparent plate.

[0023] In the embodiment shown in FIGS. 1 and 2, four decorative annular portions 22, 23, 24, and 25 are also provided and are arranged on the outer surface 5 of the lower plate 4 around the polarizer 16, which has a circular outer contour. These decorative portions are arranged in the same geometric plane as the polarizers 16 and 18 (it should be noted that the polarizers and decorative annular portions are shown in perspective in FIG. 2 relative to the elements above them). Each decorative annular portion has an inner diameter substantially equal to the radius of the polarizer 16. Furthermore, because the inner contours of the decorative portions extend along the outer contour of the polarizer 16, the gaps between these elements are also minimal and preferably invisible to the user. These decorative portions can vary. In a first example, they are portions of a colored opaque film. In a second example, they are color filters that transmit a certain amount of light, allowing the elements located below them to be seen or identified. It should be noted that in the first variant, the decorative portions are not polarizers, since the respective zones of the decorative portions are not provided with switchable displays. However, particularly for aesthetic reasons and to prevent the peripheral edges of the top / front polarizer 20 from being visible, this top / front polarizer also covers the decorative portions 22 to 25, since it extends over the entire useful surface 12 of the LCD cell 2. In a second variant, the decorative portions can be formed by the polarizers. However, no electrodes are provided facing these polarizers, so that the polarizers have a purely decorative function. Conventionally, the polarizers and the decorative portions are glued to the corresponding transparent plates.

[0024] FIG. 3 shows a second variant of the first main embodiment. All elements similar to those in the first variant will not be described again. The liquid crystal cell 42 includes a first transparent plate 4, which is the lower plate of the LCD cell 42. Two polarizers 44 and 46 are arranged beneath this plate 4, with the polarizer 46 having an opening 14A through which the polarizer 44 is placed. As with the first variant, the contour / edge of the polarizer 44 extends along the contour / edge of the opening. This second variant differs from the first variant in that the rear surface of the polarizer 46 is covered with a reflective film 48. The second variant is also distinguished from the first variant in that the assembly formed by the polarizer 46 and the reflective film 48 has a relief that visually creates a periodic or other pattern visible to the user of the watch incorporating the LCD cell 42.

[0025] 4 and 5, an LCD cell 52 forming a third variant of the first main embodiment of the watch display device according to the invention will be described, with reference to which reference numerals already described will not be repeated here.

[0026] In a third variant, at least two polarizers are provided generally side-by-side, the two polarizers having respective contours, with part of one contour running alongside part of the other.

[0027] The expression "two juxtaposed polarizers" is understood to mean that the two polarizers have contours / peripheries in which part of the contour / periphery of the first polarizer extends alongside part of the contour / periphery of the other polarizer. "Extending alongside" indicates that the part of the contour / periphery of one polarizer closely follows, and preferably is substantially parallel to, the part of the contour / periphery of the other polarizer. These two respective parts of the two contours / peripheries can preferably have a gap (small slit) between them that is barely perceptible or imperceptible to a user of the display device according to the present invention. In a specific variant, the contours / peripheries of the juxtaposed polarizers in the useful zone 12 are covered by a narrow masking strip, as described below.

[0028] In the third variant, as shown, the LCD cell 52 comprises a front polarizer 20A, specifically an absorbing transmissive polarizer, and three juxtaposed rear polarizers 54, 55, and 56 arranged in the same geometric plane 40. Whenever two or more polarizers are juxtaposed, this is understood to mean that each polarizer is juxtaposed with at least one other polarizer. Thus, in the variant shown, the polarizers 54 and 55 are juxtaposed, with the two linear portions of the contours of each of the polarizers 54 and 55 being parallel and adjacent to each other, or substantially fused together (the edges defining these two linear portions may be substantially in contact with each other). The same is true for the polarizers 55 and 56. Again, the front polarizer extends over the entire useful zone 12, completely covering the rear polarizers 54, 55, and 56 in this useful zone. The LCD cell 52 is used to form the face of a watch with an analog display 66. The LCD cell 52 forms a circular plate with a hole in its center for the passage of the axis of the analog display's hands, and the useful zone 12 corresponds to the portion of the dial visible to a user of a watch incorporating a display device comprising the LCD cell 52. The useful surface is therefore an annular zone with outer limits corresponding to the circle defined by the watchcase flange above the LCD cell. The switchable display 50 comprises three specific displays 50A, 50B, and 50C, which are formed by three polarizers 54, 55, and 56, respectively, of a plurality of polarizers disposed on the outer surface 5 of the transparent plate 4, and which are arranged in three distinct zones 57, 58, and 59, respectively, of the useful zone 12. In the given example, the switchable display 50A displays the hours and minutes of a time interval measured in stopwatch mode, while the switchable display 50B displays the seconds and hundredths of this measured time. The display 50C displays the date and month.

[0029] A reflective film 60 is disposed below and covers the three polarizers 54 to 56. The reflective film 60 is integral and is bonded to the three polarizers in a step after bonding the polarizers to the outer surface 5 of the plate 4.

[0030] Advantageously, polarizer 54 has a different color than the two polarizers 55 and 56. In one variant, the rear polarizers have different colors. A given color can also have different shades. Generally speaking, each polarizer of the plurality of polarizers can be formed by a single polarizing film or by multiple polarizing films. In other words, each polarizer is formed by at least one polarizing film. Each polarizer can be combined with a color filter and / or an underlying reflective and / or opaque film. In one variant, the lower surface of each polarizer is covered with its own reflective film having the same dimensions as the polarizer, and each polarizer is assembled with its own reflective film before being placed on transparent plate 4. It should be noted that the color filter can extend over or under the polarizer, over or under at least two polarizers individually or together, and in particular over or under all polarizers of the plurality of polarizers. It will be understood that the possible combinations available to those skilled in the art are numerous, making it possible to obtain a variety of decorative variations with different color visual effects for the background of the LCD cell and the switchable display elements.

[0031] The third variant also has a special feature that can be provided in other variants of the first embodiment, in particular the first and second variants described above, and in the variant of the second embodiment described below. This feature consists in masking the peripheries of the polarizers of the multiple polarizers in the useful zone with an opaque material, especially when two polarizers are placed side by side (first case) or when one polarizer is placed in the opening of another polarizer (second case). The opaque material covers these peripheries and thus the contours of these polarizers in such a way that it conceals (masks) any possible gaps between two respective portions of these contours that run side by side (first case) or between two contours that run side by side (second case) to the user of the watch for which the display device is designed. In the variant shown in Figures 4 and 5, the opaque material forms two linear masking strips 62A and 62B. In this variant, the transparent plate 4 is the bottom plate of the LCD cell 52, and the plurality of polarizers 54 to 56 arranged on its outer surface are rear polarizers (it should be noted that these polarizers and masking strips are shown in perspective in FIG. 5 relative to the elements located above). In this case, an opaque material is advantageously arranged on the outer surface 5 of the plate 4, between the plate 4 and the outline of the polarizers that are covered by the opaque material in the useful zone 12.

[0032] An LCD cell 72 forming a first variant of the second main embodiment of the watch display device according to the invention will now be described with reference to Figure 6. Elements already described in the first embodiment will not be described again in detail here.

[0033] In the useful zone 12, as in the first embodiment, the LCD cell 72 comprises a first plurality of polarizers 74 and 75 arranged on the outer surface 5 of the first transparent plate 4 and extending in the geometric plane 40. According to a general feature of the second embodiment, in the useful zone 12, the LCD cell 72 further comprises a second plurality of polarizers 76 and 77 arranged in a second plurality of distinct zones 82 and 84, respectively, on the outer surface 7 of the second transparent plate 6. Generally speaking, at least two polarizers 76 and 77 of the second plurality of polarizers have at least one different optical property or polarization direction between them. It should be noted that the switchable display zones are shown as in the first embodiment but are not numbered.

[0034] According to an advantageous feature, the second plurality of polarizers extend in substantially the same geometrical plane, preferably in the same geometrical plane 80 as in the example shown.

[0035] The first variant described here has two specific features. First, a first polarizer 76 of the second plurality of polarizers has an opening 78 in which a second polarizer 77 of the second plurality of polarizers is disposed, the second polarizer having an outer contour that extends along the contour of the opening. According to a second specific feature independent of the first feature, two polarizers 74, 75 of the first plurality of polarizers overlap two polarizers 76, 77 of the second plurality of polarizers, respectively, and extend into the same respective separate zones 82 and 84 in the useful zone 12. Thus, the polarizer 74 has an opening with a contour aligned with the contour of the opening 78 of the polarizer 76 in a direction perpendicular to the overall plane of the LCD cell (parallel to the geometric planes 40 and 80). Thus, the zone 82 in the useful zone 12 of the LCD cell 72 is independent of the zone 84 of this useful zone, both with respect to the background and the switchable display.

[0036] A second variant of the second embodiment will now be described with reference to Figure 7. This variant makes it possible to obtain an LCD display device with a number of zones that are visually varied for the user and that together can form relatively complex patterns that can define an original decoration.

[0037] LCD cell 92 comprises a first plurality of polarizers, polarizers 94 and 95, each partially defining a switchable display, which are arranged on the outer surface of plate 4, which in the illustrated example is the smaller plate, and a second plurality of polarizers, polarizers 96 and 97, each partially defining a switchable display, which are arranged on the outer surface of plate 6. The first plurality of polarizers extends in geometrical plane 40 and the second plurality of polarizers extends in geometrical plane 80.

[0038] The second variant has two specific features. First, at least two polarizers 96, 97 of the second plurality of polarizers are juxtaposed, each having a contour, with a portion of one contour extending alongside a portion of the other. Similarly, the two polarizers 94, 95 of the first plurality of polarizers are also juxtaposed. As a second specific feature, at least one first polarizer of the first plurality of polarizers only partially overlaps at least one second polarizer of the second plurality of polarizers. More specifically, in the variant shown, polarizer 94 partially overlaps polarizer 96 and polarizer 97, and polarizer 95 partially overlaps polarizer 96. Thus, in the useful zone, the contours of the first plurality of polarizers are not aligned with the contours of the second plurality of polarizers, and the distinct zones 104 and 105 of polarizers 94 and 95, respectively, do not overlap the distinct zones 106 and 107 of polarizers 96 and 97, respectively. As a result, this configuration means that the distinct zones of geometric plane 40 for the arrangement of the first plurality of polarizers and the distinct zones of geometric plane 80 for the arrangement of the second plurality of polarizers result in more visually varied zones than the number of first plurality of polarizers and the number of second plurality of polarizers.

[0039] In the illustrated variation, reflective film 102 is positioned only below polarizer 94, the rear polarizer.

[0040] The LCD cell 92 also includes a decorative film 100 juxtaposed with a polarizer 94 in a separate zone of the lower geometric plane 40, and two decorative films 98, 99 juxtaposed with polarizers 96, 97 in two separate zones of the upper geometric plane 80. Alternatively, the upper geometric plane 80 includes a single decorative film having openings in which the polarizers 96 and 97 are positioned, and the polarizers 96, 97 together fill the openings. The decorative films may be formed by color filters, polarizers, or other films that are opaque or reflective, flat or raised. These decorative films do not contribute to the switchable display of the LCD cell 92, but they contribute to the appearance of the LCD cell within the useful zone 12, visually distinguishing various zones within the useful zone and defining the decorative zone configuration.

[0041] FIG. 8 shows a third variant of the second main embodiment of the present invention. This variant differs from the second variant by masking the peripheral edges of the polarizers 94 and 95 and the decorative film 100, which extend in the lower geometric plane, in the useful zone, thereby masking the contours of these elements, which extend alongside each other. The LCD cell 112, like the third variant of the first embodiment, includes masking strips 114 and 115 made of opaque material. This variant differs from the second variant by masking the peripheral edges of the polarizers 96 and 97 and the decorative films 98 and 99, which extend in the upper geometric plane and are juxtaposed, in the useful zone, thereby masking the contours of these elements, which extend at least partially alongside each other, in the useful zone. For this purpose, the LCD cell 112 includes masking strips 116, 117, and 118 made of opaque material arranged above the peripheral edges. Generally speaking, the masking strip is formed by an opaque material covering the contours of the polarizers in the second plurality of polarizers so as to obscure (mask) any possible gaps between two respective portions of these contours running one alongside the other or between two contours running one alongside the other to the user of the watch for which the display device is designed. In the example shown, if in addition to said second plurality of polarizers there are decorative films arranged in the same upper geometrical plane 80, the opaque material also covers the contours of these decorative films in the useful zone.

[0042] FIG. 9 is a top view of a dial 120 formed by a display device including a liquid crystal cell 122 according to the present invention. The LCD cell 122 is fabricated in a manner similar to that described in the first or second embodiment variants, and the masking strips 132, 134, and 136 are arranged as described in the first or second embodiment variants. Multiple polarizers are arranged in separate zones 124, 126, 128, and 130. At least one of the polarizers arranged in zone 130 has three openings, and three polarizers are arranged in the three openings, each of which has at least one optical property or polarization direction different from the polarizer with the three openings. The dial 120 is attached to a watch with an analog display 66 that shows the current hour, minute, and second. The switchable display of the LCD cell 122 is configured to be used for the watch's stopwatch function. Thus, the seconds, minutes, and hours of a time interval are displayed in separate circular zones 124, 126, and 128, respectively. Separate zone 130 may display a symbol 138 related to at least one function of the watch, such as the activation of the "Bluetooth" function or the battery level. The letters "S," "M," and "H" are also part of the switchable display and may appear only when the stopwatch function is activated. This configuration is particularly advantageous when the switchable display in zones 124, 126, and 128 is desired for other information as well. In an alternative embodiment dedicated to only the stopwatch function, these letters may be obtained by using ink disposed on the dial or, possibly, on the LCD cell. In the illustrated example, zone 124 has a visual difference from zones 126 and 128, which may be a different color, including gray, or a different shade of a given color. The switchable display portion of zone 124 is of the positive contrast type, while the switchable display portions of zones 126 and 128 are of the negative contrast type.

Claims

1. A watch display device comprising a liquid crystal cell (2, 42, 52, 72, 92, 112, 122) formed from a first plate (4) and a second plate (4) that are transparent, and a bead of adhesive (8) that joins the first plate and the second plate and defines, together with the first plate and the second plate, a closed space containing a liquid crystal (10), said liquid crystal cell defines, inside the bead of adhesive, a useful zone (12) intended to define the visible zone of this cell in a watch for which said display device is designed, and incorporates electrodes (34, 35, 36, 37, 34A, 35A, 36A, 37A) forming in said useful zone a switchable display (30) of at least one item of information and / or at least one decoration, the liquid crystal cell comprises a plurality of polarizers (16, 18, 44, 46, 54, 55, 56, 74, 76, 94, 95) in the useful zone (12), the plurality of polarizers being arranged in a plurality of distinct zones (17, 19, 57, 58, 59, 104, 105) respectively on the outer surface (5) of the first plate, each of which partially forms the switchable display; A clock display device characterized in that at least two polarizers of the plurality of polarizers have at least one different optical property or different polarization direction between them, and the clock display is arranged to visually create a difference between at least respective portions of the at least two polarizers and / or between respective portions within each separate zone of the switchable display.

2. 10. The display device of claim 1, wherein the polarizers extend in substantially the same geometric plane (40).

3. 3. The display device of claim 2, wherein the at least two polarizers (54, 55, 56, 94, 95) of the plurality of polarizers are juxtaposed, the two polarizers having respective contours, at least a portion of one of the contours extending alongside at least a portion of the other.

4. 4. The display device of claim 3, wherein a first polarizer (16, 48, 74) of the at least two polarizers of the plurality of polarizers has an opening (14, 14A) in which a second polarizer of the at least two polarizers of the plurality of polarizers is disposed, the second polarizer having an outer contour that extends along the contour of the opening.

5. 4. The display device of claim 3, wherein an opaque material (62A, 62B, 114, 115) covers the polarizer contours of the plurality of polarizers so as to mask any possible gaps between two portions of each of the contours, one portion of which runs alongside the other, or between two contours, one of which runs alongside the other, to a user of a watch for which the display device is designed.

6. 6. A display device according to claim 5, characterized in that the first plate (4) is the bottom plate of the liquid crystal cell and the polarizer of the plurality of polarizers is the rear polarizer of the liquid crystal cell.

7. 7. The display device of claim 6, wherein the opaque material is arranged on the outer surface (5) of the first plate (4) between the plate and the periphery of the polarizer, the contour of which is covered by the opaque material.

8. 8. A display device according to claim 1, wherein a single polarizer (20, 20A) is arranged on the outer surface (7) of the second plate (6), this second plate being the top plate, and wherein the single polarizer is the front polarizer of the liquid crystal cell (2, 42, 52).

9. 9. A display device according to claim 8, characterized in that the single polarizer extends over the entire useful surface (12) of the liquid crystal cell.

10. 8. The display device of claim 1, wherein the plurality of polarizers is a first plurality of polarizers, the plurality of distinct zones is a first plurality of distinct zones, the liquid crystal cell (72, 92, 112) is provided with a second plurality of polarizers (76, 77, 96, 97) in the useful zone (12), the second plurality of polarizers being arranged in second plurality of distinct zones (82, 84, 106, 107) respectively on the outer surface (7) of the second plate (6), and at least two polarizers of the second plurality of polarizers have at least one different optical property or different polarization direction between them.

11. 11. The display device of claim 10, wherein the second plurality of polarizers extend in substantially the same geometric plane (80), and at least two of the second plurality of polarizers (96, 97) are juxtaposed, the two polarizers having respective contours, and at least a portion of one of the contours extending alongside at least a portion of the other.

12. 12. The display device of claim 11, wherein the second plurality of polarizers extend in substantially the same geometric plane (80), a first polarizer (76) of the second plurality of polarizers has an opening (78) in which a second polarizer (77) of the second plurality of polarizers is disposed, and the second polarizer has an outer contour that extends along the contour of the opening.

13. 12. The display device of claim 11, wherein an opaque material (116, 117, 118) covers the polarizer contours (96, 97) of the second plurality of polarizers so as to mask, to a user of a watch for which the display device is designed, any possible gaps between two respective portions of two contours that run one alongside the other, or between two contours that run one alongside the other.

14. 8. A display device according to claim 1, wherein the different optical properties between the two polarisers are colour differences.

15. 11. The display device of claim 10, wherein the difference in optical property between two polarizers in the second plurality of polarizers is a difference in color.

16. 8. A display device according to claim 1, wherein the different optical properties between the two polarizers are different shades of gray.

17. 11. The display device of claim 10, wherein the difference in optical property between two polarizers in the second plurality of polarizers is a difference in tint.

18. 8. A display device according to claim 1, wherein the first plate is a bottom plate of the liquid crystal cell and at least one of the plurality of polarizers has a rear surface covered by a reflective film (60, 48, 102).

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