WO2005041234A1

WO2005041234A1 - Electrical switch having multiple scanning and selecting ways and a single actuator

Info

Publication number: WO2005041234A1
Application number: PCT/EP2004/052413
Authority: WO
Inventors: Hervé Bricaud; Yves Pizard; David Ferraton
Original assignee: Itt Manufacturing Enterprises, Inc.
Priority date: 2003-10-15
Filing date: 2004-10-04
Publication date: 2005-05-06
Also published as: FR2861214B1; FR2861214A1

Abstract

The invention proposes a switch comprising a fixed contact holder (12) and a single upper actuator (18) for validation, which is mounted so as to move along a vertical axis in order to act on a validation trip member (14, 56), and can tilt in order to occupy several inclined selection positions, characterized in that the trip member (14) is a conducting member that is elastically deformable into a low validation position in order to establish an electrical connection between two fixed contacts (P1, P2), in that the conducting lower end of the actuator is a sphere (22) bearing on the upper face of the member (14) and in that the fixed selection contacts (C3) are arranged in a ring, with a radial clearance, around the lower conducting sphere (22) of the actuator so that the tilting of the actuator (18) is capable of causing the sphere (22) to come into contact with at least one fixed selection contact (M) in order to establish at least one selection switching way.

Description

Electrical switch having multiple scanning and selecting ways and a single actuator The invention relates to an electrical switch making it possible, by means of a single actuating member or actuator, to carry out different electrical switching operations with a view, for example, to making an electronic apparatus perform a function following choices made by selection from a menu or list on a display screen. Recent and rapidly evolving developments in telecommunication means, such as mobile radio telephones, portable computers and other devices, for which the actuation of various functions involves, for example, precise and rap id movement of a cursor on a screen, require electromechanical components of ever smaller size and, in particular in the abovementioned field, have to allow the scanning of menus, the movement of a symbol on a screen and, more generally, the combining of several electrical switching functions in a sing le component. It is especially desirable, when applied to a mobile (for example GSM or UMTS) telephone of ever decreasing size th at the user must be able to operate and control with a single han d, for such a multiple switch to be able to be thumb-operated, by being fitted onto the front main face of the telephone that bears in particular the keyboard, or on one of the two main side edges of the casing of the telephone, or beneath the main face of the telephone. The requirement for a compact control device of very small size, allowing a cursor to be moved on a screen and/or for scanning menus, such a device also being called a "navigator", is becoming increasingly important on appliances such as "mobi le telephones" or "personal digital assistants" that offer increasing numbers of functions and services involving especially choices that are proposed on one or more screens, in a manner similar to the use of a portable computer. It is thus desirable to have an electrical switch with multiple switching ways based on a single actuating member having the general form of a lever or joystick, which can be operated by a finger that acts directly on its upper free end that projects to the outside of the apparatus, or else on a button attached to this upper end. Such operations, for example by means of the underface of the thumb of the hand that is holding the apparatus, must be easy and be able to be carried out in the largest number of possible directions, very ergonomically and with low operating forces

(< 2N). In addition, such a miniaturized component must provide its user with a tactile sensation that reflects the validity of the operations performed. Tactile sensations transmitted by the switch to the user are a very important parameter as regards its performance and its ergonomics. Touch sensitivity is such that it allows the user to perceive very fine, discontinuous or continuous, variations and thus makes it possible to transmit a very complex "message" to the user's finger or hand. The finger is thus a giver (or sender) of orders for moving a cursor on the screen and/or for selecting a position of the cursor, and it is also a sensor (or receiver) that perceives tactile information in return via the single actuating member. It is thus desirable to provide the user with tactile sensations that are produced directly in response to the movement of the finger on the actuator, that is to say in its sender function. In the case of a scanning movement, such tactile information or sensations are, for example, mechanical "clicks" corresponding to each electrical signal or pulse produced by the switch for sending to the electronic signal or data processing circuits of the apparatus. Electrical selection pulses are thus produced by "scanning" the space by manoeuvres during which the actuating member is inclined at various orientations relative to a central rest position in which it lies in what is called a vertical orientation and towards which it is returned by elastic means as soon as the user releases his action on the upper operating end. The same single operating member also allows a push-in validation operation, that is to say that the electrical validation pulse is produced by moving the actuating member vertically downwards when it is in its vertical central rest position. The objective of the research that resulted in the novel design according to the present invention was especially to provide a switch meeting the following requirements: - at least n direct switching ways for the "scanning" selection, with one electrical connection output for each of the n ways, with in addition a very high degree of modularity as regards the number n of ways, which is for example equal to eight and which is not necessarily an even number; - a validation switching way; - tactile effects in selection mode and in validation mode; - very great reliability and a lifetime of the product permitting at least one million cycles per switching way, i.e. a minimum total of nine million cycles; - perfect dust-tightness; - very good centring of the actuating axis relative to the casing of the switch; - return, without backlash, of the actuator into the vertical rest position; - a very small total height or thickness of the casing, of around 1.25 mm; and - overall external dimensions of the casing that are also small, of around 6.5 x 6.5 mm. These requirements have especially resulted in the elimination of solutions such as those described, for example, in documents US-A-6 348 664 or WO-A-02/035513, which are solutions (currently used for most joysticks with n = 4 selection switching ways and one validation way that are available on the market) which are based on the pivoting of a pin provided with lateral radial arms, each arm selectively actuating an associated monostable dome or dome portion for tripping. Such solutions involve, in fact, a very difficult segregation of the selection switching ways when they number eight or more, and result in a relatively large thickness of the casing, in substantial fragility of the radial actuating arms of the trip domes, and also make it very difficult to achieve dust-tightness. To remedy these drawbacks, a switch has already been proposed in document US-A-4 739 128 with a validation way and at least two selection ways, of the type comprising a lower body 31 , 32 made of insulating material that carries fixed contacts 44, and a single upper actuator 33, 40 having the general form of a validation push knob, the upper free end portion 33 of which can be operated by a user: a) which is mounted so as to move relative to the lower body along a generally vertical validation axis in order to act on a validation trip member 38; b) and which is mounted so as to tilt, substantially about a tilt centre 40 located approximately along the validation axis, in order to occupy several angular selection positions 26 in each of which the actuator 33, 40, 42 is inclined to the vertical and establishes an electrical connection between the conducting lower end 39 of the actuator and an associated fixed electrical selection contact 44 carried by the lower body 32. However, the above document offers no industrial design making it possible in particular to meet the abovementioned series of requirements. To remedy the said drawbacks, the invention proposes a switch of the type that has just been mentioned, characterized in that the validation trip member is a central member made of conducting material and having a domed general shape that is elastically deformable from a stable, high rest position into a low validation position in order to establish an electrical connection between two fixed contacts, in that the conducting lower end of the actuator is a sphere permanently bearing axially on the upper face of the validation trip member and in that the fixed selection contacts are arranged in a ring, with a radial clearance, around the lower conducting sphere of the actuator so that the tilting of the actuator is capable of causing the sphere to come into contact with at least one fixed selection contact (facing the internal cylindrical lateral wall of the ring) in order to establish at least one selection switching way. According to other features of the invention: - the upper face of the central trip member includes a concave central well for centring the sphere at the centre of the ring and for centring the actuator in a central vertical rest position; - the centring well has a conical or frustoconical profile; - the lower conducting sphere of the actuator is permanently pressed by spring means so as to bear against the upper face of the central trip member; - the actuator includes a compression spring that is axially interposed between an upper operating push knob and the lower conducting sphere; - the lower conducting sphere of the actuator is a conductive ball that is gripped axially between a concave seat of the actuator and the upper face of the central trip member; - the actuator includes a lower part for guiding the conductive ball, the said concave seat being formed in the said part; - the lower guiding part is mounted so as to slide axially relative to the push knob; - the switch includes stop means that determine an upper axial rest position of the actuator relative to the lower body; - it includes a tubular upper body for guiding the actuator; - it includes an annular seal that is interposed radially between a facing portion of the internal wall of the tubular upper body and a cylindrical lateral face of the actuator; - the fixed selection contacts are carried by an intermediate plate which is pierced centrally by a hole, defining the said ring, and which is housed in the lower body; - the validation trip member is interposed vertically between the horizontal bottom of the lower body and the intermediate plate that bears the fixed selection contacts; - the fixed selection contacts (C3) lie in the same horizontal plane; - the central trip member is capable of establishing an electrical contact between, on the one hand, at least one common fixed electrical contact with which the validation trip member is always in contact and, on the other hand, another fixed electrical validation contact, the said contacts lying in the horizontal bottom of the lower body; - the switch includes prevention means that prevent any tilting of the actuator when the latter is in a lower/pushed-in validation position. Other features and advantages of the invention will become apparent on reading the detailed description that follows, for the understanding of which the reader should refer to the appended drawings in which: - Figure 1 is an exploded perspective view of the main components of a first embodiment of an electrical switch according to the teachings of the invention; - Figures 2 to 7 are perspective views at an angle similar to that of Figure 1 , which illustrate the successive steps of fitting and assembling the various components illustrated in Figure 1 , until a complete switch with its closed casing, as illustrated in Figure 7, is obtained; - Figure 8 is a top view on a larger scale of the lower body; - Figure 9 is a side view along the arrow F9 of

Figure 8; - Figure 10 is a perspective top view of the intermediate plate that carries the fixed selection contacts; - Figure 11 is a perspective bottom view of the intermediate plate of Figure 10; - Figure 12 is a top view on a larger scale of the intermediate plate; - Figure 13 is a side view along the arrow F13 of Figure 12; - Figures 14 and 15 are perspective detailed views, from above and below, of the upper body forming the cover of the casing of the switch according to the invention; - Figure 16 is a view on a large scale and in cross section, in the vertical plane 16-16 of Figure 8, which illustrates the switch in the rest position; - Figure 17 is a view similar to that of Figure 16, in the vertical plane 17-17 of Figure 8; - Figure 18 is a view similar to that of Figure 16, in which the actuator is shown in a tilted selection position according to a first embodiment of the actuator, with a view to establishing a selection switching way; - Figure 19 is a view similar to that of Figure 18, in which the actuator is shown in a tilted selection position similar to that of Figure 18, but in a second embodiment of the actuator; - Figure 20 is a view similar to that of Figure 16, in which the actuator is shown in the pushed-in validation position with a view to intentionally establishing the validation switching way; - Figures 21 A to 21 D are four diagrams that show, seen from above, the central portion of the intermediate plate with the eight fixed selection contacts and the conductive switching ball in various consecutive angular positions without passing back via the stable rest position; - Figures 22 to 25 are views similar to those of Figures 16 and 18 to 20 which illustrate a second embodiment of the actuator of the switch according to the invention; - Figures 26 to 29 are views similar to that of

Figure 16, which again illustrate four other embodiments of the switch according to the invention; - Figures 30 and 31 are views similar to that of Figure 16, which illustrate two alternative versions of the embodiment of the actuator illustrated in Figure 28 which include means for illuminating the push knob of the actuator; - Figure 32 is a detailed view of an illuminating diode or LED used in the switches shown in Figures 29 to 31 ; - Figure 33 is a detailed perspective view of the contact spring used in Figures 29 and 31 ; and - Figures 34 to 37 are figures illustrating the combination of a switch according to the invention with an operating or control button. Without this being limiting, a vertical, horizontal orientation will be adopted with reference to the orientation of the components in the figures. Likewise, the terms "longitudinal", "transverse" and "vertical" will be used with reference to the (L, T, V) coordinate system shown in the figures. As may be seen in Figure 1 , the electrical switch 10 according to the invention consists of an axial stacking, along the general axis A, of five main components, comprising, vertically from the bottom up: a lower body 12 carrying fixed contacts; a central validation trip member 14; an intermediate plate 16 carrying fixed selection contacts; an actuator 18; and an upper closure body 20 which, together with the lower body 12, constitutes the casing of the switch 10. In the first embodiment illustrated in particular in Figure 1 , the actuator 18 consists of an axial stacking of four components comprising, vertically from the bottom up, a conductive ball 22, a lower part 24 for guiding the ball 22, a helical compression spring 26 and an upper push knob 28 for operating the actuator 18. Finally, as may also be seen in Figure 5, a toroidal seal 30, which is a standard "O-ring" seal, is interposed radially between the push knob 28 and the upper body 20. As may be seen in Figures 2, 8 and 9, the lower body 12 consists essentially of a moulded part made of insulating plastic of square parallelepipedal general shape, the upper face of which is open in order to give access to an internal housing or cavity 32 bounded by a horizontal bottom 34. In the bottom 34, using a technique known in the field of switches, the lower body 12 includes a series of conducting pads Pi that are coplanar with the horizontal bottom 34, each pad providing a fixed contact function. In a known manner, and as may be seen in Figure 12, each conducting pad Pi belongs to a precut metal strip of conducting material, a free end of which projects laterally to the outside of the body 12 in order to form an external terminal Bi for electrical connection of the corresponding pad. Thus, considering Figure 8, the lower body 12 includes a central validation contact P1 , a peripheral conducting pad P2, which is placed substantially in the form of a ring around the central validation pad P1 and which has in particular four contact portions P2a, which are arranged as a star in the four corners of the bottom 34. The conducting peripheral pad P2 constitutes, within the meaning of the invention, a common fixed contact which is common, on the one hand, to the selection ways and, on the other hand, to the validation way of the switch 10, and also to the supply circuit for illumination means when these are provided. The conducting pad P2 is linked to two external connection terminals B2, whereas the central validation pad P1 is linked to an external connection terminal B1. The lower body 12 has here eight conducting selection pads P3 that are angularly distributed in a regular manner around the axis A, in pairs along the internal vertical lateral faces 36 that define, laterally, the cavity 32 of the support for the lower body 12. Each conducting validation pad P3 is linked to an external conducting connection terminal B3. Finally, the bottom 34 of the lower body 12 includes an additional, earth conducting pad P4, which is placed between two conducting validation pads P3 in the vertical mid-plane VMP of symmetry of the lower body 12 (see Figure 8), and which is linked to an external conducting terminal B4 on the opposite side from the conducting terminal B1 linked to the conducting validation pad P1 . The upper face 38 of the lower body 12 constitutes a horizontal bearing face for the upper body 20 and includes four positioning and crimping studs 40 for mounting and fastening the upper body 20 to the lower body 12. The lower body 12 is bounded vertically downwards by its external lower horizontal face 42, which is designed to bear, for example vertically, on a printed-circuit board (not shown) of an electronic apparatus fitted with the switch 10. As may be seen for example in Figure 16, the design of each of the external connection terminals Bi is identical, and each includes a contact portion Ti that is flush with the lower face 42 and is extended to the outside, vertically upwards, facing an outer lateral face of the body 12 by a free electrical connection branch or blade. The lower body 12 thus has twelve electrical connection terminals Bi distributed uniformly in threes along each external lateral face 37 of the insulating body 12 so as to balance the orientation and the placement of the lower body on the upper face of the printed-circuit board that carries the switch, during reflow. As may be seen in Figures 14 and 15, the upper closure body 20 of the casing of the switch 10 is, for example, a metal part or cage produced by cutting and stamping (or machining), which consists essentially of a horizontal lower closure plate 44, the lower face 46 of which is designed to bear on the upper face 38 of the lower body 12 and which has four holes 47 for passage of the crimping studs 40. The upper body 20 also includes a tubular central portion

48 that extends vertically upwards above the plate 44 and defines a vertical cylindrical internal bore 49 which opens vertically downwards in the lower face 46 and which is open vertically upwards. More precisely, the central tube 48 for guiding the actuator

18 includes an upper flange 50 that extends radially inwards in order to define a hole or orifice 52 for passage of the push knob 28 and for constituting a lower horizontal face 53 that forms an upwardly vertical stop shoulder for the push knob 28 and the actuator 18. The central trip member 14 is, in a known manner, a part made of conducting material, preferably metal, which is shaped so as to naturally occupy a stable rest position from which it can be elastically deformed into an unstable position. The part 14 is made in the general form of a dome 56 with its convexity oriented vertically upwards and is extended vertically downwards by four radial arms 57 placed regularly in the manner of a star, each arm terminating in a lower foot 58 which, in the mounted and assembled position of the components of the switch 10, permanently bears on and is in electrical contact with one of the facing portions P2a of the common conducting pad P2 of the lower body 12. The radial arms 53 and the feet 58 are housed in complementary housings 59 of the cavity 32 of the lower body 12 so as to position the trip member angularly in the body 34 and along the horizontal axes L and T without any possibility of the dome 14 moving in these directions. The largest dimension of the trip member between two opposed feet lying along a diagonal of the cavity is around 6 mm. In the stable rest position of the trip member 14, as may be seen in Figure 16, the conformation of the dome 56 is such that its central portion lies vertically above the conducting central validation pad P1 placed in the bottom 34 of the lower body 12 with a vertical clearance between them, that is to say without any electrical contact. By acting generally in a vertically downward direction on the dome 56, it is possible, in a known manner, to trip the latter, that is to say to make it "collapse", the dome deforming elastically in order to come into contact with the central conducting validation pad P1 , and to establish an electrical connection between the conducting pads P2 and P1. According to one feature of the invention, the axial central portion of the dome 56 includes a centring well 60 having a flared, substantially conical profile with its concavity oriented vertically upwards. This well 60 or "dimple" is bounded by a peripheral edge

62. The lower face 64, which is convex in relief and oriented vertically downwards, of the well 60 constitutes the central portion of the dome 56 that is capable of coming into electrical contact, at substantially a discrete point, with the central conducting validation pad P1 facing the lower body 12. In accordance with the arrangement of the invention illustrated in the figures, the central trip member 14 is interposed axially and vertically between the bottom 34 of the lower body 12 on which it bears vertically via the lower free ends of its radial arms 58, and the intermediate plate 16 that bears the fixed selection contacts. The intermediate plate 16, which will now be described in greater detail, is designed to be housed in the cavity 32 of the lower body 12. For this purpose, as may be seen in Figures 10 and 1 1 , the intermediate plate 16 is a moulded part made of insulating plastic that is bounded by a plane horizontal lower face 65 and by a parallel upper face 66. The peripheral outline of the intermediate plate 16 is of generally square shape and is designed to allow it to be placed in the cavity 32 between the internal lateral faces 36. In the mounted and assembled position of the components, the lower face 64 bears vertically downwards on three tabs 68 that are moulded together with the lower body 12 and are placed above the plane of the bottom 34 along three lateral faces 36, respectively. As may be seen in Figure 16, the lower face 46 of the plate 44 of the upper body 20 then bears vertically on the upper face 66 of the intermediate plate 16. The plate 16 has a central hole or orifice 70 that passes vertically through the plate 16. The internal concave cylindrical periphery 72 of the hole 70 has, in the example illustrated in the figures, eight fixed selection contacts C3 that are arranged angularly, in a uniform fashion, in order to constitute a ring of fixed selection contacts that all lie in the same horizontal plane corresponding approximately to the horizontal mid-plane of the intermediate plate 16. Each fixed selection contact C3 is thus an angular sector of a conducting concave cylindrical surface of vertical axial orientation. Each contact C3 is the radially internal free end of a strip of conducting material constituting an insert embedded in the body of the intermediate plate 16 and the radially external free other end of which is shaped in the form of a conducting contact blade L3. The blade L3 extends laterally to the outside of the insulating body of the intermediate plate 16 and vertically downwards in the form of a free end strand folded down in the form of a "C" that projects vertically downwards beneath the plane of the lower horizontal face 65 and each of which is in elastic vertical bearing contact, without any slack, and in electrical contact on a facing conducting selection pad P3 in the bottom 34 of the lower body 32. The "C"-shaped branches thus ensure axial "gripping" without any slack, for reliability of the electrical contacts. Thus, in the mounted and assembled position of the components, each fixed selection contact C3 is electrically connected to a conducting selection pad P3 and therefore to an external connection terminal B3. As may be seen in the figures, each fixed selection contact C3 is separated and electrically isolated from the other two contacts 03 that are adjacent thereto by an insulating radial tab 74. The moulding of the plate 16, and therefore its overmoulding around the conducting metal strips, are carried out in a mould whose shape is such that, as may be seen in Figures 10 and 1 1 , the concave surfaces of the fixed selection contacts 03 project radially inwards from the central hole 70 of the plate 16 beyond the radially internal face 76 of each insulating radial tab 74. In view of the above, and as may be seen more particularly in Figures 21 A to 21 D, each fixed selection contact is in the form of an arc along a circle that is radially inside the circle along which the faces 76 of the tabs 74 lie. Thus, the ball is never in contact with a portion 74, 76 of insulating plastic. The intermediate plate 16 also has an additional strip, which is also made in the form of an insert and is in the form of a "C"-shaped blade L4 so as to be permanently bearing on and in electrical contact with the conducting earth pad P4 (and therefore with the electrical earth connection terminal B4), and also so that its upper horizontal face 78 lies opposite a lower tab 80 for electrically earthing the lower horizontal plate 44, and therefore the upper cage 20, the tab 80 being obtained by stamping. Thus, in the assembled position of the components, the conducting metal upper body 20 is electrically connected to the conducting earth pad P4 and therefore to the earth connection terminal B4. In the first embodiment of the invention illustrated in

Figures 1 to 20, the actuator 18 consists of four axially stacked parts. The upper push knob 28 is a tubular part that is closed at its upper free end by a horizontal partition 82 and is open at its lower free end so that the lower part 24 for guiding and centring the conductive ball 22 is mounted so as to slide axially and telescopically inside the push knob 28, with axial interposition of the helical compression spring 26 that is permanently in a compressed state so as to be permanently tending to "increase" the axial length of the actuator 18. For this purpose, the lower axial end of the spring 26 bears axially on the upper end face 84 of the piece 24 whose lower free end, which permanently projects axially downwards out of the internal bore 86 of the push knob 26, has a downwardly oriented concave seat 88 that rotationally accommodates the upper portion of the spherical ball 22. The respective shape and dimensions of the concave seat 88 and of the conductive ball 22 are such that the ball 22 can never escape from the seat 88. According to the first embodiment, these dimensions are such that the contact between the ball 22 and the seat is established along a circular edge 89 of the seat 88. The body of the push knob is made of a conducting material (metal) or of an insulating material. The tubular body of the push knob 28 is staged and includes an upper portion 28S of smaller diameter, the outside diameter of which is approximately equal to the inside diameter of the hole 52. It also includes a lower portion 281 of larger diameter, which is permanently housed inside the tubular portion 48. The upper and lower portions of the push knob 28 are separated by an external radial flange 90, the horizontal upper face 92 of which constitutes a stop shoulder which, through the action of the helical compression spring 26, is returned in upward axial abutment against the horizontal lower face 53 of the flange 50, thus defining the vertical rest position of the push knob 28 relative to the upper body 20. The flange also has a peripheral fillet 55 for ensuring that there is a linear contact in the tilted position (see Figure 18). The lower portion 28I also includes an outer radial groove 94 that permanently houses the O-ring seal 30, the dimensions of which are such that it is mounted so as to be radially compressed between the radial bottom of the groove 94 and the wall of the vertical cylindrical internal bore 49. In addition, above the radial flange 90, the upper portion 281 of the actuating push knob includes a profiled inner radial groove 96 which, as will be explained later, allows the tilting movements of the actuator 18 relative to the upper body 20 and the lower body 12 of the casing of the switch. The use of a ball of very small size (for example about 0.7 mm), made of very hard steel and coated with a coating made of a very strong precious metal alloy (for example very wear- resistant PbNi on a metal ball), makes it possible to minimize the area coated with the precious metal of the conducting member that it constitutes and makes it possible to reduce wear through its rolling on the dome of the conducting member, and to substantially reduce the amount of machining if the ball is a standard commercial part produced in very high volume. As may be seen in Figure 16, the diameter of the ball is such that, in the centred rest position, there remains a substantially uniform radial gap J between the peripheral surface of the ball and the fixed selection contacts C3 that constitute the teeth of the ring of selection contacts according to the invention. The operation and use of the electrical switch 10 will now be described according to the first embodiment that was described above in detail. In the stable rest position, illustrated especially in Figures

16 and 17, owing to the relative preloading of the compression spring 26 and of the central trip member 14, the latter is in its stable rest state with the central portion of the dome 56 in the "high" position. Owing to the action of the spring 26, the conductive ball 22 is gripped axially between the guiding part 24, 88 and the trip member 14. More precisely, the ball bears on and is in electrical contact with the upper face 61 of the well 60. Unlike the concave seat 88, the profile of the flared well 60 is such that it allows the conductive ball 22 to leave the well for the purpose of making a selection. The selection or scanning function and the associated tactile sensation may be achieved, for all combinations of the various embodiments and versions described and shown, in two different modes depending on the dimensions and the force/deflection diagram that are chosen for the compression spring 26 and the trip member 14. In a first embodiment illustrated in figure 18, the conductive electrical switching ball 22 escapes from the well 60 when the actuator is tilted through an angle α relative to the vertical axis a, without "actuating" the dome 56. According to this embodiment, the electrical scanning selection switching way is closed without causing the validation switching way to be closed. The tilting generally takes place about a tilt centre C lying on the axis A. The tactile effect is obtained by the conducting member formed by the ball 22 escaping from the well and "striking" the internal radial periphery of the central hole 70, providing a radial "snapping" effect. This tactile sensation or effect may be amplified in the configurations that will be described later, shown in Figures 26 and 27 (and their combinations with versions of hemispherical end-pieces) by the radial elastic deformation of the lower end portion of the compression spring 26. A central trip member in the form of a dome without a well 60 may also be used in all the configurations if the tactile selection effect is not desired, for example in applications for games in which the minimum of effort to manipulate the joystick is desired, in order to minimize finger fatigue suffered by the user, and in which, on the contrary, it is the speed of the scanning selection action that is desired. Tilting the actuator 18 causes compression of the spring 26, the vertical component Fv of which is that exerted by the conductive ball 22 on the dome 56. When the tilt angle reaches its maximum value, which is about 10 degrees in the examples shown, the value of this component Fv remains less than the force to actuate the dome and therefore the latter is not "collapsed". The compression of the spring 26 generates a horizontal component Fh (zero in the rest state, = 0) which increases progressively as the compressive force of the compression spring increases when the angle passes from 0 to 10 degrees. Towards the end of the tilting, the value of the component Fh becomes greater than the horizontal component of the force Fr for retaining the conductive ball in the well of the dome 56. The value of the retention force Fr depends on the diameter of the ball

22, on the shape and on the dimensions of the well 60, and it is proportional to the component Fv, which itself varies proportionally with Fh during tilting, and the conducting member formed by the ball 22 suddenly escapes from the well 60, thus creating a snapping effect followed by the sudden stopping of the ball. Since the dome 56 is itself a resilient member, it sags slightly, but without collapsing, thus contributing to the snapping effect of the ball 22 as it leaves the well 60. The validation way is closed (Figure 20) by bearing vertically downwards on the actuator 18. The downward travel of the actuator firstly (over a pretravel of 0.2 to 0.3 mm) compresses the spring 26 until its turns are touching. The continuation of the descent of the actuator (the total travel of which is equal to about 0.4 to 0.5 mm) is then transmitted to the dome 56 via rigid parts 24 and 22 thus causing the trip member 12 to collapse. This continuation of the descent of the actuator 18 "locks" the actuator in the vertical orientation by cooperation of the upper portion 28S of the push knob 28 with the hole 52 for its passage. Thus, in the validation position illustrated in Figure 20, it is no longer possible to tilt the actuator 18 into a selection position. By an accurate choice of the preloading of the compression spring 26 relative to the elastic dome force 56 and relative to the kinetics of the ball 22 (in "selection" mode and in "validation" mode), the dome may also be collapsed without the turns of the spring becoming touching. To do this, it is necessary, after a travel of 0.2 - 0.3 mm of the actuator, for the compressive force of the spring 26 to reach the value of the dome force, then to exceed it during the continuation of the travel of the actuator. However, it is also necessary, during tilting of the actuator into the selection position, for the vertical compressive component of the spring 26 to remain less than the dome force. According to the second embodiment illustrated in Figure 19, the conductive ball 22 escapes from the housing or well 60 (during tilting of the actuator 18) by "actuating" the dome 56 of the central trip member 14, which "collapses", producing a very substantial tactile sensation. According to this second embodiment, the closing of the selection switching way, corresponding to the angular tilt orientation of the actuator, is accompanied by the almost simultaneous closing of the validation switching way by the trip member 14. The advantage of this second embodiment is that it provides an excellent tactile sensation, superior to that obtained by the conductive ball simply escaping from the well. In return, the software of the electronic apparatus fitted with the switch 10, which analyses all the signals and changes of state, manages this "parasitic" switching of the validation switching way. For this purpose and by way of example, the interface (not shown) of the electronic apparatus has its inputs connected to the nine switching signal outputs (eight selection ways and one validation way of the switch) and employs the following algorithm. The interface permanently scans the state of these nine outputs (0 state = "open" switching way and 1 state = "closed" switching way). When a "selection" and/or (inclusive) "validation" signal is detected, the interface temporarily records this information and, after a predetermined hold time T (for example T = 25 ms), the interface performs a new scan. The hold time T makes it possible to circumvent the chronology of the change of state of the "selection" outputs relative to that of the "validation" output. If the (or possibly both) "selection" output(s) is(are) again detected in the 1 state, this (or optionally both these) "selection" output(s) is(are) confirmed in the 1 state, whatever the state of the "validation" output. If only the "validation" output is again detected in the 1 state, the validation output must firstly be "authorized" in order to be confirmed in the 1 state. Authorization of the "validation" consists in verifying that, during the scanning which preceded that of the "temporary" scanning, the state of the "selection" was the 0 state. This makes it possible to avoid any risk of confusion if the actuator tilted in "selection" mode in one selection way is very slightly released and then again tilted in "selection" mode and whether, during this operation, the "selection" electrical contact was opened and then closed again, whereas the "validation" electrical contact remained closed (a risk that depends on the abovementioned chronology and that it is preferable to eliminate). In the second embodiment with "collapse" of the dome 56, the snapping effect obtained when the actuator is tilted into a selection function (α = 10 degrees in the examples shown) is the sum of two simultaneous phenomena. A first snapping effect is due to the ball 22 escaping from the well 60 of the dome 56 and to it stopping in contact with the contact ring. This effect is amplified by the additional relaxation of the compressing spring resulting from the sagging of the dome during its collapse. A second effect is caused by the dome sagging, the tactile effect of which is transmitted to the actuator via the rigid intermediate parts. The tactile effect resulting from these two phenomena is of course greater than that described above in the first embodiment with no sagging of the dome 56. The continuation of the descent of the actuator (0.4/0.5 mm of total travel) will of course also "lock" the actuator in the vertical position. During validation, the compression of the spring 26, resulting from it bearing vertically on the actuator, causes the dome to collapse as soon as the compressive force reaches and then exceeds the dome force (after a pretravel of 0.2 - 0.3 mm). As may be seen in Figures 21 A to 21 D, the design according to the invention makes it possible to perform a "circular scan" in the selection position. This is because, after the actuator has been tilted in order to establish a first selection switching way (Figure 21A), it is then possible, without releasing the actuator, to make it rotate about the axis A and about the centre C (for example clockwise in the figures) in order to establish a new switching way with the immediately adjacent fixed contact C3, and so on. As may be seen in the figures, the conductive sphere 22 is always in contact with at least one contact C3. The shape of the contacts C3 may provide the user with a tactile sensation of the passage from one contact C3 to the next. Likewise, upon tilting the actuator for a selection action, the ball 22 may land directly on two contacts 03 (Figure 210). With suitable processing software, it is thus possible to have a switch with sixteen selection switching ways. In the embodiment illustrated in figures 22 to 25, the lower portion of the actuator 18 is modified in that the lower part 24 mounted so as to slide telescopically inside the push knob 28 is made as a single piece with the conductive "ball" 22 which is then, as may be seen in the figures, in the form of a lower hemisphere formed at the lower free end of the part 24 which permanently extends axially to the outside of the lower portion 281 of the push knob 28. In the same manner as the ball 22 according to the first embodiment, which may be a solid metal ball, or else a ball coated with a layer of an electrically conductive coating, and especially a metal coating, the sphere 22 formed as one piece with the guiding part 24 may be made of metal, or made of an insulating material coated with a layer of conductive material. In the latter situation, it is unnecessary for the upper cylindrical body of the guiding part 24 itself to be conducting. The convex cylindrical peripheral surface of the guiding element 24 may for example be provided with a coating layer that has a low friction coefficient in cooperation with the internal wall of the bore 49 and/or may be insulating. All the modes of actuation and operation of the switch illustrated in Figures 22 to 25 are the same as that just described above with reference to the first embodiment. However, it should be noted that the conductive sphere 22 is not, of course, capable of rolling over the central trip member 14, but can only slide over the upper face of the latter. In the embodiment illustrated in Figure 26, the lower part 24 for guiding the conductive ball 22 is omitted. Consequently, it is the last lower turn 27 of the helical compression spring 26 that is directly in contact with the upper portion of the ball 22, this lower end turn 22 internally defining the concave seat 88 for guiding and retaining the ball 22. The radial elasticity of the lower portion of the spring may also increase the snapping effect at the moment when the ball escapes. All the modes of actuation and operation of the switch illustrated in Figures 22 to 25 are the same as that just described above with reference to the first embodiment. The embodiment of the actuator 18 illustrated in Figure 27 again includes a lower part 24 for guiding and retaining the conductive ball 22, with a lower concave seat 88 of conical profile. However, the cylindrical upper body of the part 24 is housed axially inside the lower free end portion of the compression spring 26. Thus, the part 24 is mounted so as to slide indirectly and telescopically relative to the push knob 28. The spring 26 is advantageously of a greater length and it acts, via its lower end turn 27, on an outer radial flange 25 of the part 24. The embodiment illustrated in Figure 28 is generally similar to the first embodiment, but it should be noted that the upper body of the tubular guiding part 24 is hollow so as to be able to house a longer compression spring 26, which is accommodated in the internal bore 23 of the part 24. In the embodiment shown in Figure 29, the guiding part 24 has a lower end-piece comprising the conductive hemisphere 22, and is fitted axially into the body of the part 24. This design makes it possible for the conducting member formed by the hemisphere 22 to be electrically isolated from the push knob 28 and from the earthed upper conducting cage 20. Examples of illumination means integrated into the push knob 28 of the actuator will now be described, especially with reference to Figures 30 and 31. The illumination of a button 1 18, which is the visible part inserted into the upper push knob 28 of the actuator 18 (see

Figure 34 et seq.) is a desirable effect for making it easier, for example, to see the position of the navigator of a mobile telephone (or PDA, etc.) in the dark. Most of the known solutions applied to current products are based on the principle of a light pipe that extends between the button and one or more LEDs (light-emitting diodes) placed on the printed-circuit board of the electronic apparatus. This light pipe complicates the assembly, generally has a low efficiency for transmitting light, and causes undesirable light leakage, for example around the button and via other interstices, especially around the button. The invention therefore proposes to place the light source directly beneath or inside the actuator. The proposed solution consists in placing the LED illustrated in detail in Figure 32 inside the actuator 18 close to its upper end. For this purpose, the upper portion 28S of the push knob has an orifice 98 allowing the light rays to directly illuminate the inside of the button since this end 28S lies inside the button. There are LEDs that have high luminosities with the following dimensions: - rectangular cross section: 0.5 x 0.6 mm; - length: 1 mm. Such LEDs are housed in the cylindrical cavity of the upper portion 28S of the push knob 28 of the actuator, the outside diameter of which is equal to 1.5 mm in the examples shown. The length of the LED 100 lies along the axis of the push knob 28 so that one 102 of the electrodes (for example the cathode) of the LED is in contact with the upper internal face 104 of the upper cavity 106 of the push knob made of an electrically conductive material, and so that its second electrode 103 (for example the anode) is in contact with the upper end turn 29 of the compression spring 26. The LED also includes a printed circuit 101 between the electrodes and a transparent casing 105. The shape of the stepped internal bore of the push knob 28 is such that it avoids any risk of a short circuit between the two electrodes 102, 103 of the LED 100 and minimizes the possibility of the LED pivoting in its housing. The compressive force applied by the compression spring 26 generates the necessary forces for the electrodes 102, 103 to bear on the conducting push knob 28 and on the compression spring 26, respectively. To make it easier to keep the spring 26 in position on the LED 100, the last turn 29 may be flared so as to "girdle" (not shown) the electrode of the lower portion of the LED 100. The electrical supply circuit for the LED 100 is as follows. The upper electrode 102, in contact with the push knob 28, is at the potential of the output corresponding to the "earth" of the cage 20, which is itself connected to the earth connection terminal B4. Because of the mobility of the actuator 18 in the tubular cavity 48 of the cage 20, it is advantageous to add an electrically conducting conical compression spring 108 having two or three turns (see Figures 31 and 33), the smallest, uppermost, turn 110 of which is elastically fitted onto the lower end-piece 1 12 of the push knob 28 of the actuator and the lower turn 1 14 of which is jammed (by radial elastic deformation of this turn) between the insulating body of the intermediate plate 16 and the base of the tubular cavity 48 of the cage 20. This conical compression spring 108 has a low force and great flexibility in order to follow all the angular and vertical movements of the actuator 28, and its function is merely to short- circuit the actuator 18/cage 20 electrical connection in order to make the electrical connection of the LED 100 reliable. Like the spring 26, the spring 108 must for this purpose be electrically conducting. The lower electrode 103, in contact with the turn 29 of the compression spring 26, is brought to the potential of the dome (and of its corresponding outputs P2 on the lower fixed contact carrier 12) via the ball 22, which is itself always pressing down on the dome 56. It is therefore necessary for the guiding piece 24 to be made of an insulating material in order to prevent a short circuit between the two electrodes 102, 103 and for its bottom to be pierced so that the lower turn 27 is in contact with the ball (see Figure 30). It is also possible to use a two-material guiding part 24, as shown in Figure 29, in which this part comprises an insulating tubular upper body 24S and a hemispherical lower end-piece 24I made of conducting material, which is fitted into the lower end of the spring 26 and the head 1 16 of which end-piece is in electrical contact with the last few lower turns of the spring 26. The orifice 98 of the push knob 28 may be closed off by a transparent material in order to optimally seal the product, although the fitting of the button may suffice in most cases in order to minimize this risk. Figures 34 to 36 show a first example of a joystick-type button 1 18, shown at rest and in cross section in Figure 34, in a tilted selection position in Figure 35, and in the pushed-in vertical position in Figure 36. Figure 34 shows the path of the light from the diode 100 through the button 118. These figures also show the relative position of the button 118 with respect to an upper wall 120 belonging to the electronic apparatus fitted with the switch 100 and its button 1 18. Figure 37 is a view similar to that of Figure 34 with a "flat" button 118. With this button, the two actuations are both in the vertical direction V, but are differentiated by acting vertically at the centre (for validation) or near the periphery of the button (for selection). Of course, the button 1 18 has fewer movements and the forces that are applied thereto are lower. The switch according to the invention makes it possible to change direction, for example along a diagonal of a screen, without releasing it and without passing back through a "neutral" or zero. The invention allows a very great modularity to be achieved by modifying the intermediate plate 16 with a different number of fixed contacts 03. The other components are identical. The "axisymmetric" components of the actuator and the ball, may advantageously be produced from metal by machining and they are then very rigid, thereby making it possible to achieve a very large number of operating cycles. The spring 26 may be omitted if the elastic force exerted permanently on the dome 14 is sufficient to ensure that the ball 22 is "gripped" axially without any play. The invention is not limited to a sphere or a portion of a sphere, but any similar shape may be used that provides the same function, for example an ellipsoid.

Claims

CLAIMS 1. Electrical switch (10) with a validation way and at least two selection ways, of the type comprising a lower body (12) made of insulating material that carries fixed contacts (Pi), and a single upper actuator (18) having the general form of a validation push knob, the upper free end portion (28) of which can be operated by a user: a) which is mounted so as to move relative to the lower body (12) along a generally vertical validation axis (A) in order to act on a validation trip member (14, 56); b) and which is mounted so as to tilt in order to occupy several angular selection positions in each of which the actuator (18) is inclined to the vertical and establishes an electrical connection between the conducting lower end of the actuator and an associated fixed electrical selection contact carried by the lower body (12), characterized in that the validation trip member (14) is a central member made of conducting material and having a domed general shape that is elastically deformable from a stable, high rest position into a low validation position in order to establish an electrical connection between two fixed contacts (P1 , P2), in that the conducting lower end of the actuator is a sphere (22) permanently bearing axially on the upper face of the validation trip member (14) and in that the fixed selection contacts (03) are arranged in a ring, with a radial clearance (J), around the lower conducting sphere (22) of the actuator so that the tilting of the actuator (18) is capable of causing the sphere (22) to come into contact with at least one fixed selection contact (C3) in order to establish at least one selection switching way. 2. Switch according to Claim 1 , characterized in that the upper face of the central trip member (14, 56) includes a concave central well (60) for centring the sphere (22) at the centre of the ring and for centring the actuator (18) in a central vertical rest position. 3. Switch according to the preceding claim, characterized in that the centring well (60) has a conical or frustoconical profile. 4. Switch according to either of Claims 2 and 3, characterized in that the lower conducting sphere of the actuator (22) is permanently pressed by spring means so as to bear against the upper face of the central trip member (14). 5. Switch according to the preceding claim, characterized in that the actuator (18) includes a compression spring (26) that is axially interposed between an upper operating push knob (28) and the lower conducting sphere (22). 6. Switch according to any one of the preceding claims, characterized in that the lower conducting sphere of the actuator is a conductive ball (22) that is gripped axially between a concave seat (88) of the actuator (18, 24) and the upper face of the central trip member (14). 7. Switch according to the preceding claim taken in combination with Claim 5, characterized in that the actuator includes a lower part (24) for guiding the conductive ball (22), the said concave seat (88) being formed in the said part. 8. Switch according to Claim 7, characterized in that the lower guiding part (24) is mounted so as to slide axially relative to the push knob (28). 9. Switch according to any one of the preceding claims, characterized in that it includes stop means (53, 92) that determine an upper axial rest position of the actuator (18, 28) relative to the lower body. 10. Switch according to any one of the preceding claims, characterized in that it includes a tubular upper body (48) for guiding the actuator (28). 1 1. Switch according to the preceding claim, characterized in that it includes an annular seal (30) that is interposed radially between a facing portion of the internal wall (49) of the tubular upper body (48) and a cylindrical lateral face (94) of the actuator. 12. Switch according to any one of the preceding claims, characterized in that the said fixed selection contacts (C3) are carried by an intermediate plate (16) which is pierced centrally by a hole (70), defining the said ring, and which is housed in the lower body. 13. Switch according to Claim 12, characterized in that the validation trip member (14) is interposed vertically between the horizontal bottom (34) of the lower body (12) and the intermediate plate (16) that bears the fixed selection contacts (C3). 14. Switch as claimed in any one of the preceding claims, characterized in that the fixed selection contacts (C3) lie in the same horizontal plane. 15. Electrical switch according to any one of the preceding claims, characterized in that the central trip member (14) is capable of establishing an electrical contact between, on the one hand, at least one common fixed electrical contact (P2) with which the validation trip member (14) is always in contact and, on the other hand, another fixed electrical validation contact (P1 ), the said contacts lying in the horizontal bottom (34) of the lower body (12). 16. Switch according to any one of the preceding claims, characterized in that it includes prevention means that prevent any tilting of the actuator when the latter is in a lower/pushed-in validation position.