CH710005B1 - Capacitive touch glass for an electronic instrument, and method for its manufacture. - Google Patents

Abstract

The invention relates to a glass (1) with capacitive keys for a portable electronic instrument, comprising a base substrate (2) and at least one insulating film (11), which is provided with electrodes (13) of the capacitive keys. The insulating film is fixed on an outer surface of the base substrate (2), and a connection device (4, 5) is provided in the base substrate. The connection device, which comprises conductive rods (4) in holes (5), makes it possible to electrically connect the electrodes of the insulating film to a processing circuit in the portable electronic instrument equipped with the glass (1). A decorative film (16) can also be fixed by means of an adhesive film (14) on the insulating film. The invention also relates to a method of manufacturing such a glass. The portable electronic instrument may be a watch.

Description

The invention relates to a glass with capacitive keys for a portable electronic instrument, in particular for a watch.

[0002] The invention also relates to a method of manufacturing a glass provided with capacitive keys for a portable electronic instrument. The glass comprises in particular an insulating film on which are produced electrodes and at least conductive tracks respectively connecting each electrode to a connection portion.

It should be understood as an electronic instrument, any portable device, such as a wristwatch, a mobile phone, a badge or another device, which can be provided with a screen or dial for displaying information above which is a glass, which closes the case of the instrument.

[0004] The production of a glass provided with one or more transparent electrodes as capacitive keys for equipping an electronic instrument is well known in particular in the field of watchmaking or mobile telephones. Usually, several transparent electrodes, which constitute capacitive keys, are arranged on an interior face of the glass of the electronic instrument, such as a wristwatch. These capacitive keys are connected to an electronic processing circuit for the command or control of functions of the electronic instrument.

[0005] The production of such transparent electrodes on the inner face of the glass is carried out by depositing a layer of conductive oxide, which may conventionally be an oxide of tin and indium (ITO), and by etching of this conductive oxide layer. The thickness of the layer obtained is generally between 25 and 75 nm, and preferably between 45 and 55 nm. Each transparent electrode is connected by a conductive track to a connection portion at the edge of the glass of the electronic instrument to be connected, via a connector, to the electronic processing circuit in the electronic instrument.

[0006] The glass, which can be made of plastic for an electronic instrument, such as a wristwatch, must be of sufficient thickness to withstand high external pressures, for example when the watch is submerged. If the glass, which has transparent electrodes on its inner face, must be of sufficient thickness, this high thickness of the glass can interfere with the correct operation of the keyboard with capacitive keys, which is a drawback.

In the case of a digital time display watch, capacitive keys can be made in the liquid crystal display device. However, since the case of such a watch is closed by an additional glass to the liquid crystal display device, a relatively large distance remains between the finger of a user placed on the outer face of the glass and an electrode of a key. capacitive to activate. This is also a drawback.

[0008] Patent application EP 2 273 349 A2 describes a method for manufacturing a transparent element, such as a glass, which comprises capacitive keys for a portable electronic instrument. An insulating film, which carries capacitive touch electrodes connected by conductive tracks, is placed in a mold. A liquid substance is inserted into the mold, in order to be solidified and to coat at least a part of the insulating film having the electrodes of the capacitive keys. On leaving the mold, a glass is thus obtained with capacitive keys integrated into the solidified material of the glass. However, provision must be made to properly position the insulating film in the mold in order to obtain good integration of the capacitive keys in the solidified substance of the glass. In addition, only a few substances can be used to produce this glass with integrated capacitive keys, which constitutes drawbacks.

[0009] The aim of the invention is therefore to overcome the drawbacks of the state of the art by providing a glass with capacitive keys for a portable electronic instrument, which is sufficiently resistant while ensuring high sensitivity of actions of the capacitive keys. activated in particular by a user's finger.

To this end, the invention relates to a glass with capacitive keys for a portable electronic instrument, which comprises the characteristics defined in independent claim 1.

Particular embodiments of the glass with capacitive keys are defined in dependent claims 2 to 15.

An advantage of the glass with capacitive keys lies in the fact that the fixing of an insulating film with particularly transparent electrodes on an outer surface of a glass of a portable electronic instrument makes it possible to make any action on them very sensitive. capacitive keys by a finger of a user. The glass of the instrument can thus be of sufficient thickness to withstand any external force or pressure without adversely affecting the operation of the capacitive keys. These capacitive keys are sealed through the glass to an electronic processing circuit of the electronic instrument. To do this, metallized holes are made through the base substrate of the glass.

To this end, the invention also relates to a method of manufacturing a glass with capacitive keys for a portable electronic instrument, which comprises the characteristics defined in independent claims 16 or 17.

Particular steps of the manufacturing process are defined in dependent claims 18 to 22.

Advantageously, the insulating film carrying the electrodes of the capacitive keys is placed and fixed on an outer surface of the base substrate of the glass while being guided by a peripheral edge of the base substrate. Another decorative insulating film can also be attached to the insulating film with capacitive keys by means of an adhesive film and following hot lamination of the films arranged one on top of the other. A connection device with holes in the base substrate and conductive rods or conductive deposits in the holes is made before or after at least for the conductive rods. The electrodes of the insulating film are electrically connected to the connection device.

The aims, advantages and characteristics of the capacitive touch glass for a portable electronic instrument, and its manufacturing process will appear better in the following description on the basis of non-limiting embodiments illustrated by the drawings in which: FIGS. 1a and 1b represent a top view and in section along AA of FIG. 1a of an embodiment of the glass with capacitive keys according to the invention, FIG. 2 represents an exploded three-dimensional view of a first form of execution of the glass with capacitive keys according to the invention, and FIG. 3 represents an exploded three-dimensional view of a second embodiment of the glass with capacitive keys according to the invention.

In the following description, all the elements which constitute the glass with capacitive keys for a portable electronic instrument, which are well known to those skilled in the art in this technical field, will only be described in a simplified manner. Reference is made mainly in the following description to a glass with capacitive keys intended to equip a wristwatch as a portable electronic instrument. However, other portable electronic instruments can be equipped with the capacitive touch glass of the invention.

In Figures 1a and 1b, there is shown a top view and in diametral section of an embodiment of a glass with capacitive keys obtained by the manufacturing process described below. The glass 1 may be of rectangular shape as shown in FIG. 1a, but also of circular shape or of another shape to be mounted preferably above a dial in a wristwatch, not shown. As shown in section in FIG. 1b, the general shape of the lens 1 may be curved, but it may be provided that this lens is also of generally planar shape, not shown.

The glass 1 firstly comprises a base substrate 2 and at least one insulating film or a set of films or layers 3 deposited or fixed on an outer surface of the base substrate 2. The film or films are flexible. The insulating film 3 carries one or more transparent or semi-transparent electrodes as capacitive keys as explained below with reference to FIG. 2.

The base substrate 2 is designed relatively rigid and of sufficient thickness to withstand significant external forces or pressures, when the glass is mounted in the watch. This base substrate 2 may preferably be transparent in its entirety or at least in a central portion so as to allow viewing of the time indications of a dial of the watch. The base substrate 2 can also be tinted. The base substrate 2 can be made of plastic or mineral material.

The base substrate 2 comprises on its upper or outer surface at least one peripheral edge 21, which is disposed continuously or in sectors on the periphery of the base substrate. The edge is dimensioned relative to the dimensions of the insulating film or of all the films or layers 3 to facilitate mounting of the insulating film or of each film or layer successively on the outer surface of the base substrate. This edge therefore also serves as a guide for the placement of the insulating film (s) to be fixed inside the peripheral edge 21.

A small gap between the inner wall of the edge 21 and the periphery of each insulating film 3 may remain after their mounting on the outer surface of the base substrate. This difference may be less than 1 mm, for example 0.1 mm for a watch glass with a width greater than 20 mm. In addition, the thickness of the edge 21 is substantially the same as the thickness of the set of films or layers 3 fixed to the outer surface of the base substrate 2 so as to form a glass of uniform thickness.

Two wedges 22, 23 are also provided in particular on the periphery of the base substrate 2 to facilitate the mounting of the glass in a watch case. These two corners are arranged laterally, for example on two opposite sides of the base substrate and preferably in the center of each corresponding side. It can be the two sides of the glass parallel to each place of attachment of a bracelet to the watch case. The two corners 22, 23 can also be of different dimensions, for example have a different length to serve as a key when mounting the finished glass on the watch case.

In the base substrate 2, there is also provided a connection device, which consists of conductive rods 4 arranged in a series of holes 5 made through the base substrate. The holes 5 with the conductive rods or deposits 4 are positioned facing an inner or lower surface of the insulating film mounted on the base substrate 2. Preferably, the number of conductive rods 4 is equal to the number of electrodes of the capacitive keys. provided on the insulating film. If 12 capacitive keys are provided, 12 holes 5 and 12 conductive rods 4 or conductive deposits are required in the holes. Preferably, the holes 5 and the conductive rods 4 are arranged on a line, which may lie parallel and close to one side of the base substrate. The inner dimension of the holes corresponds to the outer dimension of the conductive rods or conductive deposits, which entirely occupy the holes. The holes are for example less than 1 mm in diameter and are regularly spaced from one another. The conductive rods or the conductive deposits 4 protrude slightly on either side of the holes to facilitate the electrical connection of the conductive rods or deposits.

The connection device therefore makes it possible to electrically connect a connection portion of the insulating film, which comprises conductive pads connected by conductive tracks to the transparent electrodes of the capacitive keys. Preferably, the electrodes, the conductive tracks and the conductive pads are arranged on an inner or lower surface of the insulating film 3 to be facing the outer surface of the base substrate and to facilitate the electrical connection to the connection device 4, 5.

It should be noted that another type of connection device can be provided for electrically connecting the electrodes of the capacitive keys to an electronic processing circuit in the watch case. Vertical grooves on one edge of the base substrate 2 can be made and conductive deposits, for example ITO, can be made in the grooves. The grooves are of identical size and regularly spaced, and each conductive deposit can be electrically connected to the corresponding electrode of the finished capacitive touch glass. It can also be imagined that the insulating film with capacitive keys ends in a tab with connection pads, which are each connected to a corresponding electrode, in order to bend the tab over an edge of the base substrate to come and connect an electrical connector in the watch box.

FIG. 2 shows in detail a three-dimensional and exploded view of the various elements of the glass 1 with capacitive keys of a first embodiment. As can be seen, there is provided a set 3 of films or layers to be fixed on the outer surface of the base substrate 2. However, in a simple case, it is clear that only an insulating film can be provided. 11 to be fixed by gluing or hot lamination on the outer surface of the base substrate 2. The insulating film 11 carries transparent electrodes 13 preferably on an inner surface of the film facing the outer surface of the base substrate 2. It can 12 transparent electrodes 13 regularly spaced in series of 3 electrodes on the inner surface of the insulating film 11 may be provided. All the transparent electrodes of the capacitive keys can be of equivalent size in order to occupy the major part of the inner surface of the insulating film 11. Conductive tracks connect the transparent electrodes to connection pads of the insulating film to establish a connection to the connection device 4, 5. The conductive tracks, the electrodes and the connection pads, which can all be transparent, are produced by chemical etching of a layer of conductive oxide (ITO).

According to Figure 2, it can be provided above the insulating film 11 to have an adhesive film of the OCA type 14 and still above a decorative film 16. Each film or layer 11, 14, 16 can be of identical dimension to be able to be easily guided by the peripheral edge 21 of the base substrate 2 during their assembly. The insulating film 11, the adhesive film 14 and the decorative insulating film 16 can be attached to each other before mounting the set of films or layers 3 on the upper surface of the base substrate. However, preferably as each film is of suitable dimension so as to be able to be easily guided by the peripheral edge 21 during their mounting, each film is mounted successively from the upper surface of the base substrate 2. Once the mounting of the films is completed, it can be mounted successively. be carried out a hot lamination to fix in particular the insulating film 11 to the decorative film 16 by means of the adhesive film 14. The insulating film can be simply glued to the upper surface of the base substrate 2 with the connection pads in direct contact with the conductive rods 4 or conductive deposits emerging from the holes 5 of the connection device.

It should be noted that the connection device 4, 5 can be made in the base substrate 2 before mounting the film or films 11, 14, 16 on the upper surface of the base substrate. However, the connection device can also be produced after the mounting of the films 11, 14, 16, in particular the insertion of the conductive rods 4 in the holes 5 or the conductive deposits in the holes. These conductive deposits can be obtained by etching a layer of ITO or by a metal paste or by a conductive metal material, just like the conductive rods.

FIG. 3 shows in detail a three-dimensional and exploded view of the various elements of the glass 1 with capacitive keys of a second embodiment. Unlike the first embodiment presented with reference to FIG. 2, another adhesive film 18 is provided here, which is arranged between the insulating film 11, which bears the capacitive keys 13, and the upper surface of the substrate. base 2. This other adhesive film 18 comprises an arrangement of holes adapted to come exactly on the conductive holes 4, 5 of the base substrate 2. Thus after having arranged for example all the films on top of each other above the base. outer surface of the base substrate, a hot lamination of the set of films can be performed allowing the adhesive films to properly fix the set of films to the base substrate while being guided by the peripheral edge 21 of the substrate. base 2.

Of course as indicated with reference to Figure 2, it can be made the holes 5 with the conductive rods 4 or the conductive deposits in the base substrate 2 before or after mounting the set of films. It can for example be carried out first of all the holes 5 in the base substrate, then the placement of each film 11, 14, 16, 18 successively on the base substrate, their fixing by hot rolling and finally inserting the rods. conductors 4 in holes 5 or deposit metal or ITO in holes 5.

Once the glass 1 with capacitive keys is completed in the first and second embodiments presented with reference to Figures 2 and 3, an electrical connection must still be made when the glass is mounted in the watch case. To do this, there is generally provided a connector, in particular of the Zebra type, which passes through the watch face, to connect the connection terminals of a printed circuit board carrying a processing circuit, and to connect the conductive holes 4 opening into coaster 1.

From the description which has just been given, several variants of the glass with capacitive keys for a portable electronic instrument, and its manufacturing process can be designed by those skilled in the art without departing from the scope of the invention defined by the claims. Provision can be made to place the transparent electrodes on an upper surface of the insulating film and to provide metallized holes through the insulating film to connect the metallized holes of the base substrate. Several insulating films with capacitive keys can be provided and arranged fixed one on the other while ensuring a connection to the metallized holes of the base substrate. It can be provided first of all to fix the insulating film on the outer surface of the base substrate, to introduce the conductive rods into the holes of the substrate for connection to the electrodes of the insulating film, and then finally to fix the other films to the base substrate. above the insulating film.

Claims (22)

1. Glass (1) with capacitive keys for a portable electronic instrument, the glass comprising a base substrate (2), and at least one insulating film (3, 11) which is provided with electrodes (13) of the capacitive keys, characterized in that the insulating film is fixed on an outer surface of the base substrate (2), and a connection device (4, 5) is provided on or in the base substrate for electrically connecting the electrodes of the insulating film, and intended to be connected to a processing circuit in the portable electronic instrument, which is equipped with the glass (1). 2. Glass (1) with capacitive keys according to claim 1, characterized in that the electrodes (13) are arranged on a first surface of the insulating film (3, 11), which is fixed on the outer surface of the base substrate ( 2). 3. Glass (1) with capacitive keys according to claim 1, characterized in that the insulating film (3, 11) is a flexible film with the electrodes (13) arranged only on a first surface of the insulating film, which is fixed on the outer surface of the base substrate (2). 4. Glass (1) with capacitive keys according to claim 1, characterized in that the insulating film (3, 11) is fixed to the outer surface of the base substrate (2) by means of a first adhesive film ( 18) following a hot rolling operation. 5. Glass (1) with capacitive keys according to claim 1, characterized in that the outer surface of the base substrate (2) comprises a peripheral edge (21), and in that the insulating film (3, 11) is fixed. on the outer surface of the base substrate (2) inside the peripheral edge (21). 6. Glass (1) with capacitive keys according to claim 5, characterized in that the peripheral edge is dimensioned with a small gap of less than 1 mm between the inner wall of the peripheral edge and the periphery of the insulating film (3, 11) for facilitate the guiding and mounting of the insulating film on the outer surface of the base substrate. 7. Glass (1) with capacitive keys according to claim 1, characterized in that the glass comprises a decorative film (16) which is fixed to the insulating film (11). 8. Glass (1) with capacitive keys according to claim 7, characterized in that the decorative film (16) is fixed to the insulating film by means of a second adhesive film (14) following a lamination operation. hot. 9. Glass (1) with capacitive keys according to claim 1, characterized in that the glass comprises the insulating film (11) fixed to the outer surface of the base substrate (2) by means of a first adhesive film ( 18), and a decoration film (16) fixed to the insulating film (11) by means of a second adhesive film (14), and in that the assembly consisting of the first adhesive film (18), the insulating film (11), the second adhesive film and the decoration film are fixed on the outer surface of the base substrate as a result of a hot rolling operation. 10. Glass (1) with capacitive keys according to claim 9, characterized in that the dimension of each film is identical, and in that the outer surface of the base substrate comprises a peripheral edge (21) dimensioned with a small lower gap. at 1 mm between the inner wall of the peripheral edge and the periphery of the set of films to facilitate guiding and mounting of the films on the outer surface of the base substrate. 11. Glass (1) with capacitive keys according to claim 10, characterized in that the thickness of the peripheral edge (21) corresponds to the thickness of all the films to form a glass of uniform thickness. 12. Glass (1) with capacitive keys according to claim 1, characterized in that the connection device comprises conductive rods or conductive deposits (4) arranged in a series of holes (5) made through the base substrate or in a series of vertical grooves made on one edge of the base substrate (2). 13. Glass (1) with capacitive keys according to claim 12, characterized in that the number of holes (5) or grooves, and of conductive rods or deposits (4) corresponds to the number of electrodes of the capacitive keys, and in that the electrodes (13) on a first surface of the insulating film are connected by respective conductive tracks to conductive pads of a connection portion, the conductive pads being connected directly to the conductive rods or deposits. 14. Glass (1) with capacitive keys according to claim 13, characterized in that the holes (5) with the conductive rods or deposits (4) are arranged on a line corresponding to the arrangement of the conductive areas of the connection portion. insulating film. 15. Glass (1) with capacitive keys according to claim 14 characterized in that the holes (5) with the rods or conductive deposits (4) are regularly spaced. 16. A method of manufacturing a glass (1) with capacitive keys according to one of claims 1 to 15, characterized in that it comprises the steps of: - making the connection device (4, 5) in the base substrate (2), and - fixing the insulating film (3, 11) on the outer surface of the base substrate, the insulating film comprising on a first surface, the electrodes (13), which are connected by respective conductive tracks to conductive pads of a portion connection, the connection portion being directly connected to the connection device. 17. A method of manufacturing a lens (1) with capacitive keys according to one of claims 1 to 15, characterized in that it comprises the steps of: - fixing the insulating film (3, 11) on the outer surface of the base substrate, the insulating film comprising on a first surface, the electrodes (13), which are connected by respective conductive tracks to conductive pads of a portion connection, and - making the connection device (4, 5) in the base substrate (2), so that the connection device is directly connected to the connection portion. 18. A method of manufacturing a glass (1) with capacitive keys according to one of claims 16 and 17, characterized in that the insulating film is fixed to the outer surface of the base substrate by means of a first adhesive film (18) and by means of hot lamination. 19. A method of manufacturing a glass (1) with capacitive keys according to one of claims 16 to 18, characterized in that a decorative film (16) is attached to the insulating film (3, 11) before or after making the connection device in the base substrate (2). 20. A method of manufacturing a glass (1) with capacitive keys according to claim 19, characterized in that the decorative film (16) is fixed to the insulating film by means of a second adhesive film (14). and by means of hot rolling. 21. A method of manufacturing a glass (1) with capacitive keys according to one of claims 16 and 17, for which the base substrate (2) comprises a peripheral edge (21) of similar dimension to the insulating film, characterized in that the insulating film (3, 11) is arranged and guided by the peripheral edge to be fixed on the outer surface of the base substrate. 22. A method of manufacturing a glass (1) with capacitive keys according to one of claims 16 and 17, characterized in that for the realization of the connection device, conductive rods or conductive deposits (4) are made in holes (5) of the base substrate (2).