EP1734423B1 - Fitting of a tactile glass on a watch case - Google Patents

Abstract

The device has a tactile crystal (10) made of a transparent material such as sapphire, resistant to temperatures higher than 5000 Centigrade. The crystal has electrodes on an inner face (11) of the crystal connected by conductive paths (16) to contact zones (17) located in a connection area close to an edge (12) of crystal opposite ends of connectors (19). An enamel layer (20) is formed in the crystal, and conceals the electrode connection area. A hollow is made close to the edge of the crystal by a diamond grinding-wheel over a depth comprised between 0.1 millimeters and 0.5 millimeters. An independent claim is also included for a method of manufacturing a tactile crystal of a transparent material.

Description

TECHNICAL AREA

The present invention relates to a device for assembling a touch screen on a housing in which contact areas located near an edge of the ice for connecting structured electrodes on the underside of the ice to a module electronics contained in the case are masked and electrically isolated.

The invention will be more particularly illustrated by a wristwatch having a touch screen extending to the outer edge of the middle part.

BACKGROUND

The most common way of assembling a touch screen made of sapphire generally on the case of a wristwatch is explained below with reference to the figure 1 and at the schematic section of the figure 2 , in which contrasts and thicknesses have been greatly exaggerated for better understanding.

The wristwatch shown comprises in a known manner a housing 1 formed of a middle part 3 closed at its bottom by a bottom 5 and at its upper part by an ice 10 delimiting a compartment 7. The compartment 7 can accommodate a watch movement 8 to display time information on a dial 6. In the example shown, the display is an analog display by means of hour hands 9a, minutes 9b and 9c seconds.

It can also be seen that the lower face 11 of the ice 10 comprises five electrodes 15 forming, for example, capacitive sensors, said electrodes 15 being each connected by conducting tracks 16 to contact zones 17 situated near the edge 12 of the ice 10. The conductive network 15, 16, 17 is produced in known manner by structuring a transparent conductive oxide, such as indium tin oxide (ITO), deposited for example by evaporation on a thickness of between 25 and 25.degree. 75nm. The electrodes 15 and the conductive tracks 16 can be made virtually invisible by depositing dielectric layers in the spaces between said electrodes 15 and tracks 16, as described for example in the patent EP 1 457 865 . By against the contact areas 17, which are in contact with a connector 19 passing through an insulating gap 2 and connecting an electronic module 9, capable of detecting the presence of a finger above an electrode 15 and send a control signal to the movement 8, are much more visible.

When the glass 10 is assembled on the housing 1 by means of a bezel 13 made integral with the caseband, it is sufficient to give the bezel 13 a width sufficient to hide the contact areas 17. The document EP 1 122 620 discloses a housing whose contact areas are not masked by the window of the ice but by an opaque decorative layer intermediate the ice and the electrodes.

However, there are cases, in particular for wristwatches, in which the ice 10 extends to the outer edge of the middle part 3. The ice-cream 10 is assembled for example by gluing on the bearing surface of said caseband 3 or on a between insulating ring 2. To mask the glue joint it is necessary to perform a metallization by depositing near the edge of the ice at least a very thin layer of attachment, generally by evaporation of chromium, and possibly other metals or alloys to try to harmonize the color of the scope of the case seen through the ice with that of the rest of the caseband. For touch-sensitive windows there is then a significant risk of short-circuiting two adjacent contact areas 17, or creating parasitic capacitances.

SUMMARY OF THE INVENTION

The present invention therefore aims to overcome the disadvantages of the aforementioned prior art by providing a touch screen which can be assembled for example by gluing on the scope of the opening of a housing by masking the contact areas, without the risk of causing short circuits.

For this purpose, the invention relates to a device for assembling a touch screen, made of a transparent material, resistant to a temperature greater than 500 ° C. over the range of the opening of a housing, such as the case of a wristwatch. The touch-sensitive glass comprises, in a known manner on its internal face, a conductive network comprising transparent electrodes connected by conductive tracks to contact zones generally grouped together to form a connection area, facing the ends of connectors connected to an electronic module housed in a housing compartment. The touch screen is characterized in that it comprises near its edge an enamel deposit, at least a portion of the surface makes it possible to mask the connection area of the electrodes.

The transparent material resistant to a temperature greater than 500 ° C. may be a mono or polycrystalline material, for example a quartz, a spinel or a corundum, in particular sapphire. It is also possible to use an amorphous material, such as an inorganic glass, insofar as its softening point is greater than the temperature necessary to effect enamel deposition.

According to a first embodiment, the deposit of email has the form of a ribbon following the inner contour of the ice and whose width is at least equal to the width of the connection area.

It is also desirable for the conductive network to be structured on a non-discontinuous surface.

For this purpose, a hollow is made in the inner face of the ice, the contour of which substantially corresponds to at least that of the connection area, the enamel is deposited in one or more steps until it reaches a thickness of barely greater than the depth of the recess, then polishing is carried out to put the surface of the enamel at the same level as that of the ice before performing the structuring of the conductive network.

According to a second embodiment, enamel deposition is performed in a groove formed in the thickness of the ice, said groove having a depth at least equal to the width of the connection area.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 représente une montre-bracelet à glace tactile en vue de dessus ;
• la figure 2 correspond à une demi-coupe selon la ligne II-II de la figure 1 pour une montre-bracelet de l'art antérieur ;
• la figure 3 correspond à une demi-coupe selon la figure II-II de la figure 1 pour une montre-bracelet selon l'invention:

• les figures 4 à 6 représentent les différentes étapes d'un procédé permettant de réaliser une glace tactile selon l'invention, selon un premier mode de réalisation, et
• la figure 7 représente une glace tactile selon un deuxième mode de réalisation de l'invention.

Other features and advantages of the present invention will appear in the following description illustrated by a wristwatch given for illustrative and non-limiting, with reference to the accompanying drawings in which;

• the figure 1 represents a touch-screen wristwatch in top view;
• the figure 2 corresponds to a half-section along the line II-II of the figure 1 for a wristwatch of the prior art;
• the figure 3 corresponds to a half-section according to Figure II-II of the figure 1 for a wristwatch according to the invention:

• the Figures 4 to 6 represent the various steps of a method for producing a touch screen according to the invention, according to a first embodiment, and
• the figure 7 represents a touch screen according to a second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The Figures 1 and 2 have already been described to indicate which was the closest prior art, and will be described hereinafter only the figures 4 and following in which the same references are used to designate identical elements of the wristwatch.

On the figure 3 , which corresponds to a half-cut along line 11.11 of the figure 1 passing through two sensors 15, a conductive track 16 and a contact zone 17, it can be seen that the edge 12 of the ice 10 extends to the outer surface of the middle part 3 and that the said ice 10 is no longer maintained by means of a bezel attached to the caseband 3. The inner face 11 of the ice 10 has near its edge an enamel deposit 20 which extends over the entire connection area 18 (shown in dotted lines on the figure 1 ) where the five contact zones 17 of the five electrodes 15 are grouped together.

It is possible to perform this enamel deposit only at said connection area 18 and to metallize the remaining portion of the scope of the housing where there is no risk of short circuit, then proceed to assembly, for example by gluing. This procedure requires an additional step, which increases the cost, and it may be difficult, if not impossible to find the same shade and the same shade for enamel and metallization, which is troublesome when the aesthetic appearance also of importance. Therefore, it is preferred to perform the email deposition in the form of a continuous ribbon running around the ice 10 and having a width at least equal to the width of the connection area 18, so that can see the same hue all around the case.

Depending on the type of housing, it is also possible to mount the screen 10 with a plastic seal interposed.

Referring now to Figures 4 and 6 a method for producing a touch screen according to the invention is indicated hereinafter, the material constituting said mirror being, for example, a sapphire.

In a first step represented in figure 4 , a hollow 14 is made near the edge 12 of the ice 10 by means of a diamond grinding wheel to a depth of between 0.1 mm and 0.5 mm, depending on the thickness of the ice 10.

In a second step represented in figure 5 in one or more steps, an enamel deposit 20 is carried out by the known techniques of spraying, buffering or screen-printing soaking, each step being followed by a firing, until a slight overflow of the enamel is obtained above of the inner face of the ice.

According to a step not shown, it polishes the entire inner surface of the ice so as to eliminate any discontinuity between the enamel layer and the rest of the ice.

In a last step, represented by the figure 6 structuring of the conductive network 15, 16, 17 made with a transparent conductive oxide, such as indium tin oxide (ITO), is not better described as well known in the art. skilled in the art. The ice 10 can then be assembled on the scope 4 of the middle part with the interposition of an adhesive joint, and then pressing.

Referring now to the figure 7 a second embodiment is shown. As can be seen, the edge 12 of the ice 10 is machined to obtain a groove 25 in which the enamel layer 20 is formed. This embodiment has the advantage of making the porosities invisible in the mass of enamel, to facilitate machining and polishing operations including at the opening of the groove 5. This embodiment also makes it possible to carry out a polishing much easier to the surface where should be structured contact areas 17, without the risk of creating discontinuity areas that can have a detrimental effect on the conductive tracks 16 connecting the sensors 15 and the contact areas 17_

In the above description, the invention has been illustrated by a flat touch screen, but it is obvious that the invention also applies to all curved glass.

Claims (10)

1. Device including a tactile crystal (10), assembled on the shoulder (4) of the aperture of a case (1), said crystal being made of a transparent material resistant to temperatures higher than 500°C, and including on the inner face (11) thereof transparent electrodes (15) forming sensors, connected by conductive paths (16) to contact zones (17) located in a connection area (18) close to the edge (12) of the crystal (10) opposite the ends of the connectors (19) of an electronic module (9) contained in a compartment (7) of the case (1), the edge (12) of the crystal (10) including a deposition of enamel (20) at least one part of the surface of which conceals the connection area (18), such that assembly is achieved without covering by a bezel.
2. Device according to claim 1, characterized in that the enamel deposition (20) is carried out in a hollow (14) machined in the inner face (11) of the crystal (10) at least at the connection area (18).
3. Device according to claim 1, characterized in that the enamel deposition (20) is carried out in a groove (25) machined in the thickness of the crystal (10) at least at the connection area (18).
4. Device according to claim 1, characterized in that the transparent material forming the crystal is a mono or polycrystalline material for example a quartz, spinelle or corundum.
5. Device according to claim 4, characterized in that the material forming the crystal is sapphire.
6. Device according to claim 1, characterized in that the transparent material forming the crystal is an amorphous material, such as a mineral glass.
7. Device according to claim 1, characterized in that the hue of the enamel layer (20) matches that of the case (1).
8. Device according to claim 1, characterized in that the tactile crystal (10) is assembled on the shoulder (4) of the case (1) by bonding.
9. Device according to any of the preceding claims, characterized in that the compartment (7) of the case (1) further includes a watch movement (8) and a dial (6) to form a timepiece with at least partially tactile control.
10. Method of manufacturing a tactile crystal (10) of a transparent material resistant to temperatures higher than 500°C including on the inner face (11) thereof a conductive network (15, 16, 17) including electrodes (15), conductive paths (16) and contact zones (17) forming a connection area (18) including the steps of:

    - machining a hollow (14) in the inner face (11) of the crystal (10), or a groove (25) in the thickness thereof whose contour at least substantially corresponds to that of the connection area (18);

    - forming an enamel deposition (20) in the hollow (14) or in the groove (25);

    - polishing the protruding enamel surface to place it at the same level of the non-enamelled surface of the crystal, and

    - structuring the conductive network (15, 15, 17) on the inner enamelled surface and non-enamelled surface of the crystal (10).

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