CH715285B1 - Object fitted with an electro-optical display device. - Google Patents

Abstract

The invention relates to an object, in particular a portable object such as a timepiece or a smart phone, this object comprising an electrooptical display device provided with an optically active element whose optical properties can be modified by application. of an electric current or voltage between at least one electrode and a corresponding counter-electrode between which the optically active element is disposed, the object also comprising a frame (2) which delimits an opening (4) in which the electrooptical display device is arranged, the object also comprising an external electronic supply and control device (31) as well as elements (32, 34, 36) for the electrical connection of the electrooptic display device to the device external electronic supply and control (31), the external electronic supply and control device (31), m same as the electrical connection elements (32, 34, 36), being masked by the frame (2) of the object, the electro-optical display device defining an active opaque display area (38) whose surface is smaller on the surface of the opening (4) delimited by the frame (2), so that, even when the electro-optical display device is activated and that it displays information, it remains between the active display area ( 38) and the edges of the frame (2) a transparent area (40), while an area located under the active display area (38) is hidden.

Description

Description Technical Field of the Invention The present invention relates to an object provided with an electrooptical display. More specifically, the invention relates to an object such as a timepiece or a smart phone which includes a frame delimiting an opening in which the electrooptical display device is arranged.

BACKGROUND OF THE INVENTION The present invention relates to the field of electrooptical display devices. These electro-optical display devices conventionally comprise at least one substrate which serves as a support for an optically active element placed between at least one electrode and a corresponding counter-electrode and the optical properties of which can be modified by application of a voltage or an electric current. Among the display devices which meet this definition, mention may in particular be made of liquid crystal display devices (also known by their Anglo-Saxon name Liquid Crystal Display devices or LCD devices), organic light-emitting diode cells (also known by their Anglo-Saxon name Organic Light Emitting Diode devices or OLED devices), electrochromic display devices or even electrophoretic display devices.

As an illustrative example only, we can consider the case of a liquid crystal display device for example of the nematic helical type (Twisted Nematic or TN in English terminology) which comprises a front substrate which extends parallel to and away from a rear substrate. These front and rear substrates are joined together by means of a sealing frame which delimits a sealed enclosure in which the liquid crystal is confined. Electrodes and counter-electrodes are structured on the facing faces of the front and rear substrates. By applying an electrical voltage between a given electrode and counter electrode, it is possible to modify the optical properties of the liquid crystal at the point of intersection between this electrode and this counter electrode.

To ensure the proper functioning of a liquid crystal display device, it is necessary to connect the electrodes and the counter-electrodes of the latter to an electronic supply and control device located at least partly in the exterior of the display device. To this end, one of the two substrates, usually the rear substrate, is provided larger than the front substrate and this additional surface is used to extend the electric electrodes carried by the substrate with electrically conductive tracks. rear out of the sealing frame of the display. Likewise, the electrodes carried by the front substrate are transferred to the rear substrate, for example by means of electrically conductive balls dispersed in the sealing frame. These electrically conductive balls are in contact on the one hand with the electrodes, and on the other hand with conductive tracks which run on the rear substrate and which make it possible to extend these electrodes outside the sealed enclosure delimited by said sealing frame. Using electrical connectors, it is possible to connect the conductive tracks, and consequently the electrodes and counter-electrodes of the liquid crystal display device, to the external electronic power supply and control device.

There are many applications nowadays in which an object, in particular a portable object, is equipped with a device for displaying information such as a needle display device or else a device for electro-optical display, for example a liquid crystal display device of the type succinctly described above. Examples that immediately come to mind include timepieces such as wristwatches and cellphones. Such portable objects include a frame (also called "middle" in the particular case of wristwatches) which delimits an opening closed by a crystal. This glass has an upper surface facing the side of an observer and a lower surface, opposite the upper surface, facing the interior side of the portable object. The display device, for example liquid crystal or needle, is intended to display information which will be perceptible by the user through the opening delimited by the frame of the portable object.

There are in the prior art objects, in particular portable objects such as a wristwatch or a smart phone, which include a second electro-optical display device disposed above the first device. display. An example of such an object is a wristwatch which includes a helical nematic liquid crystal display device disposed above a second electrooptical display device. The front substrate through which the information displayed by the liquid crystal display device is visible has a dimension equal to or substantially the same as that of the opening delimited by the middle part of the wristwatch, while the rear substrate is larger than the front substrate in order to provide sufficient surface area to be able to arrange all the elements necessary for the electrical connection of the liquid crystal display device to its external electronic supply and control device. The portion of the rear substrate which exceeds the dimensions of the front substrate and which is used for fixing the electrical connection elements extends under the middle of the wristwatch and is therefore invisible to the user.

In these embodiments of the prior art, the active surface of the upper electrooptical display device, that is to say the extent over which such an electrooptic display device can display information, is substantially equal to the extent of the opening delimited by the frame of the object. This is very suitable in the case of an object such as a wristwatch which comprises two superimposed display devices of the electrooptical type. Indeed, the device

CH 715 285 B1 of upper electro-optical display is arranged so that, when it does not display information, it is semi-transparent and lets see the information displayed by the lower electro-optical display device. This solution is however much less suitable in the case where the lower display device is not an electrooptical display device. This is for example the case if the object such as a wristwatch is equipped, for example, with a dial above which the indicator hands move. Indeed, as the electrooptical display device which is arranged above the needle display device is disposed between two polarizers, less than 50% of the external light which falls on this electrooptical display device will penetrate the inside the watch case, so that the dial and the hands that move above it will appear dark and will be difficult for the user to perceive.

There is therefore a need in the prior art for an object, in particular a portable object such as a wristwatch or a smart phone, comprising a frame which delimits an opening through which it is possible to see, not only the information displayed by the electro-optical display device, but also the information displayed by a second display device arranged under the electro-optical display device, while masking the construction elements as well as the electrical connection elements whose view would harm the aesthetic appearance of the object.

Summary of the invention The present invention aims to meet the needs described above as well as others by providing an object, in particular a portable object such as a timepiece or a smartphone, provided with a first electro-optical display device and optionally with a second display device arranged under the electro-optical display device, the information displayed respectively by the first electro-optical display device and by the second display device 'display being perceptible through the opening delimited by the frame with which the object is equipped. In particular, all the elements necessary for the electrical connection of the first electrooptical display device to its external electronic supply and control device must remain imperceptible to the user. To this end, the present invention relates to an object, in particular a portable object such as a timepiece or a smart phone, this object comprising an electrooptical display device provided with an optically active element, the optical properties can be modified by applying an electric current or voltage between at least one electrode and a corresponding counter-electrode between which the optically active element is disposed, the object also comprising a frame which delimits an opening in which the electro-optical display device is arranged, the object also comprising an external electronic supply and control device as well as elements for the electrical connection of the electro-optical display device to the external electronic supply and control device, the external electronic power and control device, as well as the electrical connection elements, being masked by the frame of the object, the electrooptical display device defining an active opaque display area whose surface is less than the surface of the opening delimited by the frame, so that , even when the electrooptical display device is activated and that it displays information, there remains between the active display area and the edges of the frame a transparent area, while an area located under the active display area is hidden.

Thanks to these characteristics, the present invention provides an object, in particular a portable object such as a wristwatch or a smart phone, provided with an electrooptical display device including an active opaque display area having a surface which is less than that of the opening delimited by the frame of the object. Consequently, even when the active display area displays information, there remains around this active display area and up to the edge of the object frame, a transparent area devoid of any displayed information through which one perceives. very distinctly what is located under the electrooptical display device. The user therefore has a direct and clear view of what is located under the transparent area. Conversely, the active display area of the electrooptical display device being opaque, we do not perceive what is located under this active display area. An object is thus obtained, in particular a wristwatch, which can be described as mysterious since the active display area of the electrooptic device is surrounded by a transparent area which does not allow anything to be seen from the external electronic device of power supply and control as well as elements for the electrical connection of the electrooptical display device to the external electronic power supply and control device, so that the active display area seems to be connected to nothing.

According to a particular embodiment of the invention, the opening which is delimited by the frame is closed by the electrooptical display device.

According to another particular embodiment of the invention, the object comprises a lens which closes the opening and which comprises an upper surface facing the outside of the object, and a lower surface facing the inside of the object and against which the electrooptical display device is fixed.

According to yet another particular embodiment of the invention, the electrooptical display device comprises a transparent front substrate by which the electrooptic display device is fixed against the lower surface of the glass, the display device electrooptics also comprising a rear substrate which extends parallel to and at a distance from the front substrate, the dimensions of the front substrate being equal to or substantially the same as those of the glass, while the dimensions of the rear substrate exceed those of the glass so to have a sufficient surface to be able to arrange the elements necessary for the electrical connection of the electrooptical display device.

CH 715 285 B1 According to yet another particular embodiment of the invention, the object comprises a second device for displaying information arranged under the electrooptic display device and at least partially visible through the transparent area.

An example which illustrates the possibilities offered by the present invention is that of a wristwatch equipped with an electro-optical display device in accordance with the present invention and further comprising a dial provided with needles arranged under the electrooptical display device. Thanks to the characteristics of the invention, the user of the wristwatch thus simultaneously sees through the opening delimited by the middle of his watch the digital information displayed by the active area of the electrooptical display device, and the analog information. displayed by the hands that move above the dial. Thanks to the invention, a hybrid watch is thus obtained provided with a display of the "screen" type and with an analog display, the appearance of which is original and innovative. However, care will be taken to note that the present invention is not limited to the use of an analog display device placed under the electrooptical display device, and that it is very possible to envisage combining a first and a second electro-optical display device between them, the second electro-optical display device then being adapted to display information in areas which are not covered by the active display area of the first electro-optical display device. We can thus choose to activate only the first electrooptical display device fixed under the glass, or else activate only the second electrooptic display device placed under the first, or else activate the first and second electrooptical display devices simultaneously.

BRIEF DESCRIPTION OF THE FIGURES Other characteristics and advantages of the present invention will emerge more clearly from the following detailed description of an embodiment of a portable object of the wristwatch type according to the invention, this example being given purely by way of non-limiting illustration only in conjunction with the appended drawing in which:

fig. 1 is a partial sectional view of a watch case, a middle part defining an opening closed by a crystal against the lower surface of which is secured an electrooptical display device of the liquid crystal display device type;

fig. 2 is a top view of the watch illustrated in FIG. 1, and fig. 3 is a view similar to that of FIG. 1 in the case where the electro-optical display device is an OLED organic light-emitting diode display device.

Detailed description of an embodiment of the invention The present invention proceeds from the general inventive idea which consists in arranging an electrooptical display device in an opening delimited by a frame of an object, in particular an object portable such as a wristwatch or smart phone. The originality of the electrooptical display device is that its dimensions are the same or slightly greater than those of the opening, but that its active display area is opaque and has a surface whose dimensions are smaller than those of the opening. Consequently, even when the electrooptical display device is activated and that it displays information, there remains between its active display area and the edges of the frame of the object a transparent area devoid of any displayed information which confers on the object is mysterious because it does not allow the user to guess what and how the electrooptical display device is connected for the needs of its power supply and its control. According to a particular embodiment of the invention, a second device for displaying information arranged under the electrooptical display device is at least partially visible through the transparent area. This second device for displaying information can be of any type: it can simply be a decorative motif; it can also be a second electro-optical display device. According to a preferred embodiment of the invention, the second display device is a dial above which the hands move. Thanks to the invention, a hybrid watch is thus obtained provided with a display of the "screen" type and with an analog display, the appearance of which is original and innovative. In particular, all the elements located under the transparent zone are perfectly visible to the user, while the elements which are located under the active display zone are imperceptible. The present invention will be described in connection with a portable object. of the wristwatch type equipped with an electrooptical display device of the liquid crystal display device type. It goes without saying that this example is given purely by way of illustration and not by way of limitation only and that the object may be something other than a timepiece. It is very generally any type of object such as a telephone or a laptop including a frame which delimits an opening through which information displayed by the electrooptical display device is perceptible. Similarly, the choice of the electrooptical display device is not limited to liquid crystal display devices and extends in particular to display devices of the organic light-emitting diode type as well as to electrophoretic display devices and electrochromic display devices. Indeed, these different types of electrooptical display devices all comprise at least one substrate which serves as a support for an optically active element (liquid crystal, for example nematic in helix or super nematic in helix or else in vertical alignment

CH 715 285 B1 for a liquid crystal display device, active hole injection layers for a display device with organic light-emitting diodes, black and white particles or color particles dispersed in a fluid in the case of display devices. electrophoretic display, liquid or solid electrolyte in the case of electrochromic display devices), and sets of electrodes and counter-electrodes used to modify the optical properties of the optically active element by applying a voltage or an electric current.

Note that for the purposes of the present invention, the term active display area of an electrooptical display device the useful portion of the front surface of the electrooptical display device on which information elements can be displayed. By way of example, in the case of an electro-optical display device of the helical nematic liquid crystal type, we are dealing with two front and rear substrates which extend parallel to and at a distance from one of the other and which are joined together by a sealing frame which delimits a sealed enclosure for the confinement of the liquid crystal. A front polarizing film is attached to the top of the front substrate and its direction of polarization forms an angle of 90 ° with the direction of polarization of a rear polarizing film attached to the underside of the rear substrate. We then say that the polarizers are crossed. In this case, the information displayed by the electrooptical display device in its active display area will appear dark on a transparent background. To make the active display area appear opaque, the rear polarizing film can be combined with a reflector or else an opaque backlighting device is provided on the underside of the rear substrate. Instead of the backlighting device, an opaque film may also be suitable.

It is also possible that the polarizers are parallel, that is to say that their polarization directions are parallel to each other. Yet another embodiment consists of combining a circular polarizer fixed on top of the front substrate with a metal reflector arranged inside the liquid crystal display device, on top of the rear substrate. The active display area is therefore defined as the volume of liquid crystal between the front polarizing film and the rear polarizing film or between the circular polarizing film and the metal reflector.

Designated as a whole by the general reference numeral 1, the wristwatch box shown only partially and in section in FIG. 1 includes a frame 2 which we will hereinafter preferably call "middle". This middle part 2 defines an opening 4, for example circular, which is closed in a perfectly sealed manner by a glass 6. This glass 6 comprises an upper surface 8 turned towards the side of the user, and a lower surface 10, opposite the surface upper 8 and turned towards the inside of the wristwatch box 1. An electrooptical display device, in this case a liquid crystal display device 12, comprises a transparent front substrate 14 fixed everywhere suitable means against the lower surface 10 of the glass 6. This front substrate 14 extends parallel to and at a distance from a rear substrate 16 also transparent. The front 14 and rear 16 substrates are joined together by means of a sealing frame 18 which defines a sealed enclosure 20 for the confinement of a liquid crystal 22. The liquid crystal display device 12 is for example secured by laminating by means of an optically transparent adhesive (Optical Clear Adhesive or OCA in English terminology) against the lower surface 10 of the glass

6. The optically transparent adhesive has the advantage of avoiding the problems of parasitic optical reflections at the interface between the glass 6 and the liquid crystal display device 12. Electrodes 24 made of an electrically conductive transparent material such as tin-indium oxide (Indium Tin Oxide or ITO in English terminology) are structured on a lower face 26 of the front substrate 14 of the liquid crystal display device 12, while counter-electrodes 28, they also made of an electrically conductive transparent material, are structured on an upper face 30 of the rear substrate 16. The electrodes 24 and the counter-electrodes 28 are arranged on either side of the liquid crystal layer 22. By application of an appropriate electrical voltage between a given electrode and counter electrode, the optical properties of the liquid crystal 22 are changed at the cross point ent between the electrode and the counter electrode considered.

The dimensions of the front substrate 14 of the liquid crystal display device 12 are identical to or greater than those of the opening 4 delimited by the middle part 2. As for the rear substrate 16, its dimensions are larger than those of the substrate before 14 and it partially extends under the middle 2 of the wristwatch. It must in fact be borne in mind that the electrodes 24 and the counter electrodes 28 must be connected to an external electronic supply and control device 31. To this end, the rear substrate 16 is provided larger than the front substrate 14 and this additional surface area is used to extend by first electrically conductive tracks 32 made of a transparent electrically conductive material such as oxide. of tin-indium or ITO the counter-electrodes 28 carried by the rear substrate 16 outside the sealing frame 18 of the liquid crystal display device 22. Similarly, the electrodes 24 carried by the front substrate 14 are transferred to the rear substrate 16 for example by means of electrically conductive balls and dispersed in the sealing frame 18. These balls allow the electrodes 24 to be brought into electrical contact with second conductive tracks 34 also made of an electrically conductive transparent material such as of ΙΊΤΟ and which run on the rear substrate 16, making it possible to extend these electrodes 24 out of the enclosure watertight bounded by said sealing frame 18. Thanks to a flexible printed circuit 36, also known by its Anglo-Saxon name Flexible Printed Circuit or FPC, it is possible to connect the conductive tracks 32, 34 and, consequently, the electrodes 24 and the counter electrodes 28 of the liquid crystal display device 12, to the external electronic supply and control device 31 arranged on a printed circuit board 37. As the first and second conductive tracks 32, 34 are transparent and that the flexible printed circuit 36 is hidden by the middle part 2 of the wristwatch, all of these elements are invisible to the user. Preferably, the printed circuit board 37 is arranged under the liquid crystal display device 12.

CH 715 285 B1 As already indicated above, the active display area 38 of the liquid crystal display device 12 is defined by the volume of the liquid crystal 22 confined within the perimeter of the sealing frame 18 and which lies between an upper polarizer 39 and a lower polarizer 41. These polarizers 39, 41 can be crossed, that is to say that their directions of polarization form a right angle, or else parallel, it is that is, their directions of polarization extend parallel to each other. According to the invention, and as is apparent from Figs. 1 and 2 annexed to the present patent application, the extent of this active display area 38 is less than the surface of the front substrate 14. Consequently, even when the liquid crystal display device 12 is activated and that 'it displays information, there remains between its active display area 38 and the edges of the middle part 2 of the wristwatch a transparent area 40 devoid of any displayed information through which it is possible to see a second device for information display 42 arranged under the liquid crystal display device 12. This second information display device 42 can be of any type: it can simply be a decorative motif; it can also be a second electro-optical display device. According to a preferred variant embodiment of the invention illustrated in FIGS. 1 and 2, the second display device 42 is formed by a dial 44 above which the first and second hands 46 and 48 move. Thanks to the invention, a hybrid watch is thus obtained provided with a display of the "screen" type and an analog display whose appearance is original and innovative.

It goes without saying that the present invention is not limited to the embodiment which has just been described and that various modifications and simple variants can be envisaged by those skilled in the art without departing from the scope of the invention as defined by the appended claims. In particular, it will be understood that, within the meaning of the present invention, the opening delimited by the frame of the object, for example the middle part of a wristwatch, can be closed either directly by the electrooptical display device , or by a glass on a lower face of which is fixed the liquid crystal display device. Thus, as described above, the liquid crystal display device 12 can be secured against the lower surface 10 of the glass 6 by means of its front substrate 14. It can nevertheless also be envisaged to dispense with the glass 6 and to close the opening 4 delimited by the frame 2 of the portable object directly by means of the front substrate 14 of the liquid crystal display device 12.

According to another embodiment of the invention illustrated in FIG. 3, an OLED organic light emitting diode display is used. Referred to as a whole by the general reference numeral 50, this OLED display device comprises a transparent front substrate 52 which serves as a support for a stack of organic layers 54 sandwiched between an anode 56 and a cathode 58. All of the layers of the OLED display device 50 is protected from humidity by means of a cover 60 which defines a sealed enclosure in which a humidity absorbing device 62 is arranged. As a variant, all of the layers of the OLED display device 50 can be protected by depositing thin layers. These thin layers can be deposited by atomic layer deposition, a technique better known by its Anglo-Saxon name Atomic Layer Deposition or ALD. A flexible printed circuit 64 makes it possible to connect the OLED display device 50 to an external electronic supply and control device 66 arranged on a printed circuit board 68 via conductive tracks 70 which extend outside the sealed enclosure delimited by the cover 60. Preferably, the printed circuit board 68 is disposed under the OLED display device 50. The active display area 72 of the OLED display device 50 is defined by the overlap area between the anode 56 and cathode 58. This active display area 72 has a metallic appearance in the absence of a circular polarizer, and will have a dark appearance if such a circular polarizer is used. According to the invention, and as is apparent from FIG. 3, the extent of the active display area 72 is less than the area of the opening 4 delimited by the frame 2 of the portable object. Consequently, even when the OLED display device 50 is activated and it displays information, there remains between its active display area 72 and the edges of the frame 2 of the portable object a transparent area 74 devoid of any displayed information through which it is possible to see a second display device 42 such as a dial 44 above which the first and second hands 46, 48 move. In the example shown in FIG. 3, the OLED display device 50 is of the bottom emission type (bottom emission in English terminology), that is to say that the light emerges from the OLED display device 50 through the front substrate 52. It is therefore quite possible to close the opening 4 delimited by the frame 2 of the portable object by means of the front substrate 52. Of course, it is also possible to close the opening 4 by means of a glass 6 and securing the OLED display device 50 against the lower surface 10 of the glass 6 via its front substrate 52. In the case where the OLED display device 50 is of the top emission type (top emission in English terminology), that is to say in the case where light emerges from the OLED display device on the side opposite to the front substrate 52, it may be envisaged to close the opening 4 delimited by the frame 2 of the portable object directly by means of the cover 60 of the disp OLED display positive 50, or by securing the cover 60 against the lower surface 10 of the glass 6. In the case where the OLED display device 50 is protected from moisture by depositing thin layers on the assembly of its layers, the OLED display device 50 is fixed against the lower surface 10 of the glass 6 by means of the thin layers.

Nomenclature [0027]

1. Wrist watch box

2. Frame

CH 715 285 B1

4. Opening

6. Ice

8. Upper surface

10. Bottom surface

12. Liquid crystal display device

14. Front substrate

16. Rear substrate

18. Sealing frame

20. Waterproof enclosure

22. Liquid crystal

24. Electrodes

26. Lower face

28. Counter electrodes

30. Upper side

31. External electronic power and control device

32. First electrically conductive tracks

34. Second electrically conductive tracks

36. Flexible printed circuit

37. Printed circuit board

38. Active display area

39. Upper polarizer

40. Transparent area

41. Lower polarizer

42. Second display device

44. Dial

46, 48 First and second needle

50. OLED organic light-emitting diode display

52. Front substrate

54. Stack of organic layers

56. Anode

58. Cathode

60. Lid

62. Moisture absorbing device

64. Flexible printed circuit

66. External electronic power and control device

68. Printed circuit board

CH 715 285 B1

70. Guide tracks

72. Active display area

74. Transparent area

Claims (14)

Claims 1. Object, in particular a portable object such as a timepiece or a smart phone, this object comprising an electrooptical display device provided with an optically active element whose optical properties can be modified by application of a current or electrical voltage between at least one electrode and a corresponding counter electrode between which the optically active element is disposed, the object also comprising a frame (2) which delimits an opening (4) in which the electro-optical display device, the object also comprising an external electronic supply and control device (31; 66) as well as elements (32, 34, 36; 64, 70) for the electrical connection of the display device electrooptical to the external electronic power supply and control device (31; 66), the external electronic power supply and control device (31; 66), m same as the electrical connection elements (32, 34, 36; 64, 70), being masked by the frame (2) of the object, the electrooptical display device defining an active opaque display area (38; 72) whose surface is less than the surface of the opening ( 4) delimited by the frame (2), so that, even when the electrooptical display device is activated and that it displays information, it remains between the active display area (38; 72) and the edges of the frame (2) a transparent area (40; 74), while an area located under the active display area (38; 72) is hidden. 2. Object according to claim 1, characterized in that the opening (4) delimited by the frame (2) is closed by the electrooptical display device. 3. Object according to claim 1, characterized in that it comprises a glass (6) which closes the opening (4) and which comprises an upper surface (8) facing the outside of the object, and a lower surface (10) turned towards the interior side of the object and against which the electro-optical display device is fixed. 4. Object according to claim 2, characterized in that the electro-optical display device comprises at least one transparent front substrate (14; 52) by which the electro-optical display device closes the opening (4) delimited by the frame (2 ), the transparent front substrate (14; 52) serving as a support for the optically active element which is arranged between at least one electrode and a corresponding counter-electrode and whose optical properties are modified by application of a voltage or a current between the electrode and the corresponding counter electrode. 5. Object according to claim 3, characterized in that the electro-optical display device comprises at least one transparent front substrate (14; 52) by which the electro-optical display device is fixed against the lower surface (10) of the glass. (6), the transparent front substrate (14; 52) serving as a support for the optically active element which is arranged between at least one electrode and a corresponding counter-electrode and the optical properties of which are modified by application of a voltage or a current between the electrode and the corresponding counter-electrode. 6. Object according to one of claims 4 and 5, characterized in that the electrooptical display device also comprises a rear substrate (16) transparent which extends parallel to and at a distance from the front substrate (14), the dimensions of the front substrate (14) being equal to or greater than that of the opening (4) delimited by the frame (2), while the dimensions of the rear substrate (16) exceed those of the front substrate (14) in order to have 'A sufficient surface to be able to arrange the elements (32, 34, 36) necessary for the electrical connection of the electrooptical display device to the external electronic device (31) supply and control. 7. Object according to claim 6, characterized in that the electrooptical display device is a liquid crystal display device (12), and in that the front (14) and rear (16) substrates are joined together by means of a sealing frame (18) which delimits a sealed enclosure (20) for the confinement of a liquid crystal (22), a volume of liquid crystal (22) comprised between an upper polarizer (39) and a polarizer lower (41) or between a polarizer and a metal reflector defining the active display area (38) of the liquid crystal display device (12). 8. Object according to claim 7, characterized in that it comprises a flexible printed circuit (36) which makes it possible to connect the liquid crystal display device (12) to the external electronic device (31) supply and control via electrically conductive tracks (32, 34) which extend outside the sealed enclosure (20) delimited by the sealing frame (18). 9. Object according to one of claims 4 and 5, characterized in that the electrooptical display device is an OLED display device (50) whose transparent front substrate (52) serves as a support for a stack of organic layers (54) sandwiched between an anode (56) and a cathode (58), the OLED display device (50) being protected from humidity by means of a cover (60) which defines a sealed enclosure in which a moisture absorbing device (62) is arranged, or else by depositing thin layers on the stack formed by the anode (56) and the cathode (58) between which the stack of organic layers extends (54). CH 715 285 B1 10. Object according to claim 9, characterized in that the active display area (72) of the OLED display device (50) is defined by the overlap area between the anode (56) and the cathode (58) . 11. Object according to one of claims 9 and 10, characterized in that it comprises a flexible printed circuit (64) which makes it possible to connect the OLED display device (50) to an external electronic device (66) of supply and control via conductive tracks (70) which extend outside the sealed enclosure defined by the cover (60) or by the thin layers. 12. Object according to one of claims 1 to 11, characterized in that it comprises a second display device (42) of information arranged under the electrooptical display device and at least partially visible through the area transparent (40). 13. Object according to claim 12, characterized in that the external electronic device (31; 66) for supply and control is arranged under the second display device (42). 14. Object according to one of claims 1 to 12, characterized in that the external electronic device (31; 66) for supply and control is arranged under the electrooptical display device.