AU2015293775B2

AU2015293775B2 - Trim for electric switch and method of assembling same

Info

Publication number: AU2015293775B2
Application number: AU2015293775A
Authority: AU
Inventors: Corinne MINGOUT
Original assignee: Legrand SNC; Legrand France SA
Current assignee: Legrand SNC; Legrand France SA
Priority date: 2014-07-21
Filing date: 2015-07-17
Publication date: 2020-08-06
Anticipated expiration: 2035-07-17
Also published as: AU2015293775A1; RU2017105406A3; CO2017000073A2; EP3172751A1; BR112017000107B1; FR3023965A1; RU2017105406A; FR3023965B1; RU2678832C2; EP3172751B1; CN106605283A; BR112017000107A2; CN106605283B; ES2742890T3; WO2016012700A1

Abstract

The invention relates to trim (200) for an electric switch comprising a trim plate (210) of which a peripheral part (211) is provided with a central aperture (214) delimited by an internal edge of said peripheral part (211), characterized in that the trim plate (210) comprises a central part (212) positioned in the central aperture and surrounded by a gap (215) defined between the external edge of the central part (212) and the internal edge of the peripheral part (211) to accommodate a control button (220) for operating the electric switch surrounding the central part (212). A method of assembling such a trim (200) is also described.

Description

TRIM FOR ELECTRIC SWITCH AND METHOD OF ASSEMBLING SAME

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates to an electrical accessory. It relates more particularly to a trim unit for an electrical switch and to a method of assembling it.

TECHNOLOGICAL BACKGROUND In order to perform its functional role of electrical switching, an electrical switch conventionally includes an accessory mechanism in which two contact elements make or break contact as a function of the position of a rocking driver. The accessory mechanism is usually mounted in an accessory support that includes fastener means for fastening in a box that is fitted on or in a wall surface. The external appearance of the electrical switch is generally determined by a trim unit that comprises two separate elements: a control member that is mounted on the driver and a trim plate that is mounted on the accessory support. This conventional design implies that the control

member forms the central portion of the trim unit (the

control member being surrounded by the trim plate) and thus

offers little freedom concerning the external appearance of

the electrical switch.

"Comprises/comprising" when used in this specification

is taken to specify the presence of stated features,

integers, steps or components but does not preclude the

presence or addition of one or more other features,

integers, steps, components or groups thereof.

SUMMARY OF THE INVENTION In a first aspect of the invention, there is provided a trim unit for an electrical switch comprising a trim plate having a peripheral portion that is provided with a central recess defined by an inner edge of said peripheral portion, wherein the trim plate includes a central portion that is arranged in the central recess and that is surrounded by a gap defined between the outer edge of the central portion and the inner edge of the peripheral portion so as to receive a control member of the electrical switch surrounding the central portion. Such a structure makes it possible to enlarge the options available concerning the shape of the control member, and consequently gives greater freedom in defining the external appearance of the electrical switch. The trim unit may include the control member; the control member may thus extend in the gap. Other characteristics of the trim unit that are non limiting and advantageous are as follows: • the central portion and the peripheral portion are mounted on a first portion and a second portion respectively of a front face of a backplate; • the first portion and the second portion are interconnected by at least one bridge that is situated at the rear of the backplate; • the bridge includes two side portions that extend rearwards respectively from the first portion and from the second portion, and that form between them a gap for receiving the control member; • the rear face of the trim plate carries positioner means that ensure determined relative positioning of the central and peripheral portions of the trim plate; • said positioner means comprise keying means that are arranged in an asymmetric pattern both on the central portion and on the peripheral portion of the trim plate, and that are adapted to co-operate with counterparts that are provided on the backplate or on a tool;

- the keying means are housings that are recessed in the rear face of the central and peripheral portions; • the outer edge of the central portion has a shape that is circular; - the outer edge of the central portion has a shape that is rectangular or square; • the control member surrounds the central portion; • the gap is annular and the control member has a shape that is generally circular in a plane in which the trim plate extends; and - the control member has a shape that is generally square or rectangular in a plane in which the trim plate extends. In another aspect of the invention, there is provided a method of assembling a trim unit for an electrical switch including a trim plate, the method comprising the following steps: • cutting a central portion and a peripheral portion of the trim plate out from a block of material, the peripheral portion being provided with a central recess defined by an inner edge of said peripheral portion; and - assembling the central portion and the peripheral portion in such a manner as to form a gap between the outer edge of the central portion and the inner edge of the peripheral portion, the gap being for receiving a control member of the electrical switch. Provision may also be made for a step of mounting the central portion and the peripheral portion on a first portion and a second portion respectively of a front face of a backplate; by way of example, the first portion and the second portion are interconnected by at least one bridge that is situated at the rear of the backplate.

3a

In certain embodiments, the mounting step comprises the following sub-steps performed in this order: • mounting the central portion on the first portion; - mounting the control member on the backplate; and mounting the peripheral portion on the second portion.

The mounting step may also comprise the following sub steps: - placing the backplate on a tool; and

[continued on page 41

placing the trim plate on the backplate in such a manner that positioner means of the trim plate co-operate with complementary elements of the tool. By way of example, the positioner means comprise at least one housing formed in the rear face of the central portion and/or one housing formed in the rear face of the peripheral portion. This is particularly advantageous in order to ensure relative positioning between the central portion and the peripheral portion, as explained below.

DETAILED DESCRIPTION OF EMBODIMENTS The following description of non-limiting examples given with reference to the accompanying drawings, makes it possible to understand what the invention consists of and how it can be reduced to practice. In the accompanying drawings: - Figure 1 is a front view of an accessory mechanism used in an electrical switch in accordance with the teaching of the invention; - Figure 2 is a section view of the accessory mechanism on plane A-A shown in Figure 1; - Figure 3 is a perspective view of a driver of the accessory mechanism shown in Figures 1 and 2; - Figure 4 is an exploded view showing a trim unit in accordance with the teaching of the invention together with the Figure 3 driver; - Figure 5 shows the assembled Figure 4 trim unit in its mounted position on a vertical wall; - Figure 6 shows a backplate of the trim unit shown in Figures 4 and 5; - Figure 7 is a first view of a detail of the Figure 6 backplate; - Figure 8 is a second view of a detail of the Figure 6 backplate;

- Figure 9 is a perspective view of another embodiment of a trim unit in its mounted position on a vertical wall; - Figure 10 is a front view of a trim unit of the type of trim unit shown in Figure 5, having a trim plate that presents a pattern; - Figure 11 is a front view of a trim unit of the type of trim unit shown in Figure 9, having a trim plate that presents a pattern; - Figure 12 is a rear view of the Figure 10 trim plate before being cut out; - Figure 13 is a rear view of the Figure 10 trim plate after being cut out; - Figure 14 is a front view of a tool used to assemble a trim unit including the Figure 13 trim plate; - Figure 15 is a section view on line B-B in Figure 14; - Figure 16 shows the peripheral portion of the trim plate being placed on the Figure 14 tool; and - Figure 17 shows the central portion of the trim plate being placed on the Figure 14 tool. Figures 1 and 2 show an accessory mechanism 100 (in this embodiment a switch mechanism) of an electrical switch. In the present description, the terms "front" and "rear"! are thus used relative to the direction in which the user looks at the wall surface on which the electrical switch is fitted. Thus, when the switch is installed in a room, "front" means the face facing into the room, and "rear" means the face facing the opposite way, away from the room. The accessory mechanism 100 includes an insulating base 110 that forms a support for supporting the accessory mechanism in a box such as a flush-mounted box, as explained below. The base 110 includes a body 112 from which a side wall 111 extends forwards. The base 110 is open at the front and presents a housing that is adapted to receive the other elements of the accessory mechanism. The body 112 presents a front face 112a that co operates with the inside face of the side wall 111 to define the housing. The body 112 also presents a rear face 112b remote from the front face 112a. The accessory mechanism also includes a cap 120 that is an insulating part mounted in the base (e.g. by snap fastening), and that holds the electrically-conductive parts housed in the base 110, in particular electrical connection terminals for connecting to the local electricity network. In conventional manner, the electrical-connection terminals are automatic-connection terminals, such that each of them is operable by a disconnection lever that passes through an opening formed in the wall of the base 110 so as to act on a spring blade of the corresponding terminal, which spring blade is adapted to flatten the stripped end of the electrical conductor against the cage of the connection terminal. Each disconnection lever includes a control lever 125 that is carried by the cap 120 and that is accessible to the user on the outside of said base 110. The accessory mechanism 100 also includes a brush 141 that is adapted to rock about a rocking axis between two extreme positions, so as to make or break contact between a movable contact element, e.g. a movable contact stud that is carried by the brush, and at least one stationary contact element, e.g. a stationary contact stud that is carried by a contact blade that is itself electrically connected to one of the electrical connection terminals. The accessory mechanism 100 also includes a driver 130 that is mounted to rock on the base 110 by means of two pins 133 that are formed on the driver 130 and that are engaged respectively in two corresponding bearings 118 formed in the base 110, e.g. at the top of two projecting portions 117 of the body 112 of the base 110, thus forming a rocking axis for rocking the driver 130 in the base 110. The driver 130 is an insulating part, e.g. made by molding plastics material, that includes both a connection piece for connecting to a control member, which connection piece extends in the housing formed in the base 110 as mentioned above, and also a chimney 136 that extends rearwards along a direction that is generally perpendicular to the connection piece, at the rocking axis, through an opening 124 formed in the cap 120 for this purpose. The connection piece of the driver 130 is described in greater detail below with reference to Figure 3. As can be seen clearly in Figures 1 and 2, the cap 120 is thus mounted in the housing formed in the base 110 between the body 112 of the base 110 and the connection piece of the driver 130. Finally, the accessory mechanism 100 includes resilient toggle means (not shown), e.g. a spring mounted in the chimney 136 formed on the driver 130. After passing through a hard point, the resilient toggle means are suitable for urging the brush 141 towards one or the other of its extreme positions as a function of the position of the driver 130. The accessory mechanism 100 is for mounting in a box (not shown) for fitting on, or in, a wall surface, either by surface mounting the box on the wall or by flush mounting it in the wall. To do this, the base 110 presents holes 113 that are formed respectively in tabs 114 that extend towards the outside of the base 110 from the front end of the side wall 111: each of the holes 113 is for passing the threaded shank of a screw (having a head that bears against the edge of the hole) for screw fastening in a corresponding tapped cylinder (not shown) of the box (e.g. a flush-mounted box), thereby making it possible to fasten the accessory mechanism 100 in the box.

As shown in Figures 1 and 2, in this embodiment of generally cylindrical shape, the side wall 111 of the base 110 presents catches 115 at a plurality of positions along its inside periphery for co-operating with anchor means for anchoring a trim unit, as described below, so as to mount the trim unit on the accessory mechanism 100. Figure 3 is a perspective view of the driver 130. The connection piece of the driver 130 presents the general shape of a disk (having a circumference that is essentially coaxial with the cylindrical side wall 111) from which four arms 131, 132, 134, 135 extend. A first arm 134 and a second arm 135 respectively extend on either side of the disk in the general direction of the rocking axis of the driver 130 (and thus in register with a pin 133). Each of the first and second arms 134 and 135 is provided with a recess 137 (in this embodiment an open recess) suitable for co-operating with a complementary portion of a control member, as explained below. A third arm 131 and a fourth arm 132 extend on respective sides of the disk in a direction that is generally perpendicular to the rocking axis of the driver 130. In the embodiment described, the first arm 134, the second arm 135, the third arm 131, and the fourth arm 132 are thus distributed regularly over the circumference of the disk. Each of the third and fourth arms 131 and 132 is terminated at its free end by a bead 139 that projects forwards. At the disk and in the general direction in which the third and fourth arms 131 and 132 extend, the connection piece of the driver 130 presents two recesses 138 (in this embodiment open recesses), that are situated on either side of the center of the disk and that are for co-operating with complementary portions of a control member of a type other than the type mentioned above.

Figure 4 is an exploded view showing a trim unit 200 in accordance with the teaching of the invention, and the driver 130. The trim unit 200 comprises a trim plate 210, in this embodiment formed by a peripheral portion 211 and by a separate central portion 212, a control member 220, and a backplate 230. The outside of the peripheral portion 211 of the trim plate 210 has a shape that is generally rectangular and presents a central recess 214, in this embodiment a circular recess having a diameter that (ignoring clearance) corresponds to the outside diameter of the control member 220, in this embodiment an annular control member, such that the circular central recess 214 can house both the annular control member 220 and also the central portion 212, which in this embodiment is in the shape of a disk, the central portion 212 being at the center of the control member 220, as can be seen clearly in Figure 5, which shows the assembled trim unit. In the general plane in which the trim plate 210 extends (which plane is parallel to the general plane in which the backplate 230 extends as described below), the control member 220 (in its mounted position as shown in Figure 5) extends along a line that forms a closed curve (in the shape of a circle in the embodiment of Figures 4 and 5). In its mounted position and while lying it in the general plane in which the trim plate 210 extends, the central portion 212 of the trim plate 210 thus extends inside the closed curve formed by the control member 220, while the peripheral portion 211 extends outside the closed curve. In other words, the trim plate 210 includes an opening (or gap) 215, in this embodiment an annular gap, defined between the inner edge of the central recess of the peripheral portion 211 and the outside edge of the central portion 212, through which the annular control member 220 emerges.

Naturally, in other variants, provision could be made for the opening of the trim plate to follow a closed line that is square or rectangular (or a closed line of any other shape, e.g. triangular or oval), the control member, that is received in the opening, thus presenting a matching shape that extends along a square or rectangular closed curve (or, in general manner, a shape that corresponds to the shape of the opening). As shown more particularly in Figure 4, the backplate 230 includes a plane front face that is interrupted at a plurality of positions such that the front face defines two side portions 231, 232 (a left side portion 231 and a right side portion 232) and two central portions 233, 234 (a left central portion 233 and a right central portions 234). The unit formed by the two central portions 233, 234 is separated from the unit formed by the two side portions 231, 232 by an annular gap 243 in which the annular control member 220 is received in its mounted position. The unit formed by the left side portion 231 and by the left central portion 233 is also separated from the unit formed by the right side portion 232 and by the right central portion 234 by a generally rectangular opening 244 that is defined at each of its two ends by an arm of material 239 that connects together the left side portion 231 and the right side portion 232, and that is crossed in its center by a cylinder portion 240 (as can be seen clearly in the view of a detail in Figure 8), connecting together the left central portion 233 and the right central portion 234. As can be seen clearly in Figure 6, which shows the rear face of the backplate 230, each central portion 233, 234 is also connected to the corresponding side portion 231, 232 by means of two bridges 235. Each bridge 235 is formed by a first side wall 236 that extends rearwards from the outer periphery of the central portion 233, 234 under consideration, by a second side wall 237 that extends rearwards from an inner edge of the side portion 231, 232 under consideration, and by a rear wall 238, essentially parallel to the front face of the backplate 220 and set back relative to said backplate, and interconnecting the first side wall 236 and the second side wall 237. As a result of its shape, each bridge 235 thus serves to participate in mechanically connecting a central portion 233, 234 to a side portion 231, 232, while leaving the above-mentioned annular gap 243 free, in particular in the plane of the front face of the backplate 230, in order to receive the annular control member 220 in this annular gap 243. It should also be observed that for each bridge 235, the outer surface of the second side wall 237 presents grooves 242 that form the anchor means for coming to co operate with a corresponding catch 115 of the base 110 of the accessory mechanism 100, so as to hold the trim unit 200 on the accessory mechanism 100 as mentioned above. In this respect, the second side walls 237 of all of the bridges 235 lie in a cylinder of diameter that is substantially identical to the diameter of the cylindrical side wall 111 of the base 110 of the accessory mechanism 100 so that, while the trim unit 200 is being mounted on the accessory mechanism 100, the bridges 235 become interfitted in the housing formed by the base 110, as mentioned above. Despite the interruptions in material (annular gap 243, generally rectangular opening 244), the front face (in particular formed by the side portions 231, 232 and by the central portions 233, 234) extends over more than half the available surface area as a result of the dimensions of the backplate 230. In other words, in the plane of the front face of the backplate 230, the surface area of the front face (mainly the solid portions 231, 232, 233, 234) is greater than the combined surface area of the annular gap 243 and of the generally rectangular opening 244. The plane front face of the backplate 230 thus forms a good support for the trim plate 210, specifically for the rear face (which is also plane) of the trim plate 210, e.g. in view of assembly by adhesive bonding as explained below. On two teeth that extend rearwards respectively from the rounded outer edges of the left central portion 233 and of the right central portion 234 that define the annular gap 243, the backplate 230 respectively includes two pins 241 of generally cylindrical shape (one of which can be seen on the view of a detail in Figure 7) for co operating with corresponding recesses 221 that are formed in the annular control member 220 so that the annular control member 220 can be pivotably mounted on the backplate 230 about a pivot axis that, in the mounted position of the electrical switch, is parallel to the front face of the backplate 230, and that corresponds to the rocking axis for rocking the driver 130 on the base 110. By way of example, a lug 245 is also provided situated at the base of each pin 241 in order to limit the lateral clearance of the annular control member 220. In addition, each central portion 233, 234 also presents a slot that, in the mounted position, is designed to leave a free gap for passing a respective one of the two projecting portions 117 of the body 112 that form the bearings 118. As already described above, the control member 220 has a generally annular shape that enables it to be situated, in the general plane in which the trim plate 210 extends, inside the peripheral portion 211 of the trim plate 210, and to surround the central portion 212 of the trim plate 210. Specifically, the control member 220 comprises a main body 222 that forms a portion of a sphere such that the diameter of the main body 222 at its rear peripheral end (situated at the rear of the front face of the trim plate 210 in its mounted position) is greater than the diameter of the main body 222 at its front peripheral end (situated at the front of the front face of the trim plate 210 in its mounted position), and this gives the main body 222 of the control member 220 a barrel shape that matches the central portion 212 of the trim plate 210 as closely as possible, tapering a little from said trim plate in a forward direction. As can be seen more clearly in Figure 4, the control member 220 also includes two tabs 223 that extend rearwards from the main body 222. In the embodiment described, the two recesses 221 for receiving the cylindrical pins 241 provided on the backplate 230 are respectively formed in the two tabs 223. Finally, the control member 220 includes two projections 226 each of which extends rearwards a little from the rear edge (in this embodiment a circular rear edge) of the main body 222, over a portion only of the circumference of the rear edge that is distinct from the portions carrying the tabs 223. In the mounted position of the electrical switch (i.e. when the trim unit 200 is mounted on the accessory mechanism 100), the rear end of each tab 223 is housed in the corresponding complementary recess 137 that, as mentioned above, is formed in the driver 130 (as shown by the dashed lines in Figure 4) so that when the user rocks the control member 220 (in this embodiment about the pivot axis formed by the cylindrical pins 241, in alignment with the rocking axis of the driver 130), which also causes one of the projections 226 of the control member 220 to bear against the corresponding bead 139 of the driver 130, the driver 130 is caused to rock and the electrical switch is thus caused to switch. In order to assemble the trim unit 200 as shown in Figure 5, the central portion 212 of the trim plate 210 is fastened (e.g. by adhesive-bonding) on the central portions 233, 234 of the front face of the backplate 230; the annular control member 220 is then mounted on the backplate 230 by co-operation between the cylindrical pins 241 and the recesses 221 (e.g. by acting on the springiness of the tabs 223 during mounting). Finally, the peripheral portion 211 of the trim plate 210 is fastened (e.g. by adhesive-bonding) on the side portions 231, 232 of the backplate 230. The trim unit 200 may thus be sold in the form of a single-piece product. In the embodiment described, it should be observed that the backplate 230 (specifically its front face) and the trim plate 210 (specifically the peripheral portion 211 of the trim plate 210) have practically the same external dimensions; provision could be made for the trim plate 210 to have dimensions (length, width) that are a little greater than the dimensions of the front face of the backplate 230, so that only the trim plate 210 can be seen when the electrical switch is viewed from the front. In addition, the installer or the user purchases an accessory mechanism 100 of the type shown in Figures 1 and 2 and described above, and mounts the accessory mechanism 100, as already described above, in a box that is fitted in or on a wall surface. The installer or the user thus mounts the trim unit 200 on the accessory mechanism merely by interfitting the side wall 111 of the base 110 of the accessory mechanism 100 and the outer wall of the second side wall 237 of the bridges 235 formed at the rear of the backplate 230 (the catches 115 co-operating with the grooves 242 as explained above), and this also enables the co-operation (mentioned above) between the tabs 223 of the control member 220 and the recesses 137 of the driver 130, and thus the control of the switching of the electrical switch by means of the control member 220. It should be observed that the trim plate 210 (made up of its peripheral portion 211 and of its central portion 212) completely covers the front face of the backplate 230 (in particular the peripheral portions 231, 232 and the central portions 233, 234 of the front face of the backplate 230). In particular, the gap formed between the peripheral portion 211 and the central portion 212 extends in register with the annular gap 243 formed between the central portions 233, 234 and the side portions 231, 232 of the front face of the backplate 230. As can be seen clearly in Figure 5, the user can thus see only the edge of the backplate 230 once the trim unit 200 is mounted (by means of the accessory mechanism 100) on a wall surface. Figure 9 is a perspective view of another embodiment of a trim unit 300 in its mounted position on a vertical wall. As mentioned above, the control member is not necessarily circular but may present a shape in section that is generally rectangular or square (or, in a variant, any other shape) in the general plane in which the trim plate 310 extends, as for the control member 320 shown in Figure 9. In this embodiment, the trim plate 310 comprises a peripheral portion 311 that presents a central opening that is square, and a central portion 312 that is also square in shape. In a variant, provision could be made for the central opening and/or the central portion 312 to be rectangular in shape. The length of an outer edge of the central portion 312 (in this embodiment the length of the side of the square central portion 312) is a little shorter than the length of the corresponding inner edge of the central opening of the peripheral portion 311 (in this embodiment the length of the side of the square central opening) so as to form a gap 315 (in the general plane in which the trim plate 310 extends) between the peripheral portion 311 and the central portion 312, which gap 315 (or space) extends along a closed curve over the entire outer periphery of the central portion 312, and may thus house the control member 320 having a general shape that corresponds to the shape of the gap). As for the embodiment shown in Figure 5, the control member 320 is mounted to pivot on a backplate 330 having a front face that carries the central and peripheral portions 312, 311 of the trim plate 310. By way of example, such a backplate 330 is of the same type as the backplate 230 shown in Figures 6 and 7, except for the shape of the annular gap 243 (that is of shape that is generally square in the embodiment in Figure 9). In some circumstances, the outside of the front face of the trim plate 210, 310 presents a pattern that is to run on in continuous manner between the peripheral portion 211, 311 and the central portion 212, 312 of the trim plate 210, 310, in particular when the peripheral portion 211, 311 and the central portion 212, 312 are made by being cut out from a single block of material. As shown in Figures 10 and 11, this situation applies in particular to trim plates 410, 510 made out of wood and having an outside surface (in particular the front face) that presents grain: it is desirable for the grain visible on the central portion 412, 512 to run on from the corresponding grain on the peripheral portion 411, 511. This problem exists for materials other than wood, such as slate or brushed materials. In addition, the pattern that is to run on in continuous manner between the central portion 412, 512 and the peripheral portion 411, 512 may also be decoration provided on the front face of the trim plate (e.g. a pattern), typically when it is advantageous to place such a decoration on the front face of the trim plate before said trim plate is cut out in order to obtain the peripheral portion and the central portion. An example of a solution is described below that makes it possible to ensure that after the trim unit has been assembled, the peripheral portion and the central portion of the trim plate are arranged so as to preserve the continuity of a pattern that is present both on the peripheral portion and on the central portion of the trim plate. Figure 12 shows a rear view of the trim plate 410' before being cut out. In this figure, dashed lines show the lines of cut that subsequently enable the central portion 412 and the peripheral portion 411 to be separated, while leaving a gap or space (in this embodiment an annular gap) between the two portions. On each zone 411', 412', corresponding to a respective future portion 411, 412, at least one housing 416', 417', 418', 419' is formed in the rear face of the trim plate 410', in a manner that is asymmetrical relative to the portion under consideration. For example, in zone 412', corresponding to the central portion 412, at least one housing 418', 419' is formed that is not circularly symmetrical about the center of the central portion 412 (that has the shape of a disk in this embodiment, as mentioned above). Specifically, as a result of the circular outer shape of the central portion 412, it could be placed in any angular orientation in the absence of keying means such as housings 418', 419', as explained below. In addition, in the zone 411', corresponding to the peripheral portion 411, at least one housing 416', 417' is formed that is not symmetrical relative to the horizontal or vertical middle axis of the peripheral portion 411. Specifically, since the outer shape of the peripheral portion 411 is rectangular, only two mounting positions are possible for this portion in the absence of keying means such as the housings 416', 417'. In the embodiment shown in Figure 12, the zone 411', corresponding to the peripheral portion 411, includes (as housings) an oblong recess 416' that is formed in the top portion of the rear face of the finishing plate 410' before cutting out, and a circular recess 417' that is formed in the bottom portion of the rear face. In this embodiment, the oblong recess 416' and the circular recess 417' are made on a vertical middle axis of the trim plate 410' before cutting out. Similarly, the zone 412', corresponding to the central portion 412 includes (as housings) an oblong recess 418' that is formed in the rear face of the trim plate 410' before cutting out, in the top portion of the zone 412', and a circular recess 419' that is formed in the rear face, in the bottom portion of the zone 412'. In this embodiment, the oblong recess 418' and the circular recess 419' are made on a vertical middle axis of the trim plate 410' before cutting out. In the embodiment described, it should be observed that the housings 416', 417', 418', 419' (in the rear face of the trim plate) are situated at locations that are designed to be situated in register with recesses of the backplate 230 (in this embodiment in register with the generally rectangular opening 244) when the trim plate and the backplate are assembled together. This makes it possible for the housings 416', 417', 418', 419' to co-operate with complementary elements of a tool that is used for assembly, as described below. In a variant, provision could however be made for the housings 416', 417', 418', 419' (in the rear face of the trim plate) to be situated at locations that are designed to be situated in register with the front face of the backplate 230 when the trim plate and the backplate are assembled together. In this circumstance, it is the front face of the trim plate that presents elements, of respective shapes that are complementary to the various housings, in order to co-operate with them and constrain the peripheral portion and the central portion to be mounted in predetermined positions on the backplate.

Figure 13 shows a rear view of the trim plate 410 after being cut out, i.e. after separating the peripheral portion 411 and the central portion 412. Although the two portions 411, 412 are shown in Figure 13 in the relative position that they have before being cut out, and that they must have after being assembled on the backplate 230 so as to form a trim unit, in reality they are separate at this step of the process and their relative positioning is thus not under control. However, they can be positioned correctly in order to assemble them on the backplate 230 by means of the housings 416', 417', 418', 419' as explained below. Figures 14 and 15 show a tool 600 that is used during assembly of a trim unit in a possible implementation of the invention. The tool 600 presents a shape that is generally a rectangular plate having a large face that has dimensions that are greater than or equal to the dimensions of the trim plate 410 that is to be assembled. The tool 600 presents a central opening 610 having a shape that corresponds to the shape of the second side wall 237 of the backplate 230, in this embodiment a shape that is circular. An arm 620 passes through the central opening 610, which arm extends through the central opening 610 on a middle axis of the tool 600. The front face of the arm 620 extends in the plane of the front face 605 of the overall tool 600 (i.e. the front face of the above mentioned rectangular plate). Similarly, the rear face of the arm 620 may extend in the plane of the rear face of the tool 600. On the above-mentioned middle axis, the front face 605 of the tool 600 presents projections 616, 617, 618, 619 having shapes that are complementary to the shapes of the respective recesses 416', 417', 418', 419' formed in the rear face of the trim plate 410 as explained above and as shown in Figure 13. The projections 616, 617,

618, 619 thus form counterparts of the housings 416', 417', 418', 419'. Specifically, in the top region of its front face, the arm 620 presents an oblong projection 618 having a shape that is complementary to the shape of the oblong recess 418', and, in the bottom region of its front face, it presents a circular projection 619 having a shape that is complementary to the shape of the circular recess 419'. In its region situated immediately above the arm 620 (see in particular Figure 14), the front face 605 of the tool 600 presents an oblong projection 616 having a shape that is complementary to the shape of the oblong recess 416'. In its region situated immediately below the arm 620, the front face 605 of the tool 600 presents a circular projection 617 having a shape that is complementary to the shape of the circular recess 417'. It should be observed that, in its front face situated as mentioned above in the plane of the front face 605 of the tool 600, the arm 620 also presents a central recess 621 of dimensions that are sufficient to house the cylinder portion 240 when the backplate 230 is mounted on the tool 600 as explained below and as shown in particular in Figure 16. In its front face, in each of the end regions of the arm 620, the arm 620 also presents a recess 622 that is designed for potentially receiving a corresponding portion of the control member 220 while mounting the trim unit, in particular while mounting the control member 220 on the backplate 230 (the backplate 230 itself being positioned on the tool 600 as mentioned above). Figure 16 shows the peripheral portion 411 of the trim plate 410 being placed on the tool 600, thereby making it possible to mount the peripheral portion 411 on the backplate 230. It should be observed that the backplate 230 is identical to the backplate described above with reference in particular to Figure 6.

As can be seen in Figure 16, the backplate 230 is initially placed on the tool 600 (the rear face of the backplate 230 in contact with the front face of the tool 600) so that the second side wall 237 of the backplate 230 comes into contact with the central opening 610 of the tool 600. Since the second side wall 237 and the opening 610 are circular, the final positioning of the backplate 230 on the tool 600 is, for example, obtained by verifying the alignment of the side edges of the backplate 230 and of the tool 600 (the two parts having the same dimension in a given direction, in this embodiment along the horizontal edge of the backplate 230), or by verifying the alignment of the outer side edges of the arms 620 and of the corresponding inner edges of the generally rectangular opening 244. The projections from the front face 605 of the tool 600, in particular the projections 616, 617 formed on the front face 605 outside the arm 620, are thus situated in the generally rectangular opening 244 and they extend beyond the front face of the backplate 230. Specifically, to do this, it should be observed that the height of each of the projections 616, 617, 618, 619 is greater (by at least 1 millimeter (mm)) than the thickness of the backplate 230 in its regions forming its front face (in particular the side portions 231, 232 and the central portions 233, 234 mentioned above). The peripheral portion 411 of the trim plate 410 may thus be placed on the backplate 230 so that the oblong recess 416' (shown in Figure 13) co-operates (by complementary shapes) with the oblong projection 616, and so that the circular recess 417' (shown in Figure 13) co operates (by complementary shapes) with the circular projection 617. As a result of the difference in shape between the oblong elements (oblong recess 416', oblong projection 616) and the circular elements (circular recess 417', circular projection 617), there is only one possible way of positioning the peripheral portion 411 on the tool 600. It should be observed that the same one-position result is obtained by using only one of the two positioner elements on the tool 600 (e.g. the circular projection 617) and the complementary element on the peripheral portion 411 (in this embodiment the circular recess 417 '), whenever the rectangular edges of the peripheral portion 411 are in alignment with the edges of the backplate 230. However, the use of two positioner elements, as in the embodiment shown in the figures, makes it easier to position the peripheral portion 411 on the tool 600, and thus on the backplate 230 positioned beforehand on the tool 600 as explained above. Before positioning the peripheral portion 411 on the tool 600, the side portions 231, 232 of the front face of the backplate 230 can be covered with a suitable adhesive, so that by placing the peripheral portion 411 on the tool 600, it is possible to bond the peripheral portion 411 adhesively on the backplate 230 (possibly by applying pressure on the front face of the peripheral portion 411). Figure 17 shows the central portion 412 of the trim plate 410 being placed on the tool 600, thereby making it possible to mount the central portion 412 on the backplate 230. As can be seen in Figure 17, and as described below, the central portion 412 is put into place after the peripheral portion 411 has been put into place, as described above with reference to Figure 16. However, it should be observed that it is entirely possible for the central portion 412 to be placed on the tool 600 (and thus mounted on the backplate 230) before the peripheral portion 411, using the same process as that described above. Putting the central portion 412 into place before the peripheral portion 411 may even be desirable, e.g. when the shape of the control member 220 makes it necessary, as explained above with reference to Figures 4 and 5. Either way, at the beginning of the method of putting the central portion 412 into place, the backplate 230 is positioned on the tool 600 (the rear face of the backplate 230 in contact with the front face of the tool 600), as indicated above with reference to Figure 16. The projections from the front face 605 of the tool 600, in particular the projections 618, 619 formed on the front face of the arm 620, are thus situated in the generally rectangular opening 244 and they extend beyond the front face of the backplate 230. The central portion 412 of the trim plate 410 may thus be placed on the backplate 230 so that the oblong recess 418' (shown in Figure 13) co-operates (by complementary shapes) with the oblong projection 618, and so that the circular recess 419' (shown in Figure 13) co operates (by complementary shapes) with the circular projection 619. As a result of the difference in shape between the oblong elements (oblong recess 418', oblong projection 618) and the circular elements (circular recess 419', circular projection 619), there is only one possible way of positioning the central portion 412 on the tool 600. It should be observed that the same one-position result is obtained by using only one of the two positioner elements on the tool 600 (e.g. the circular projection 619) and the complementary element on the central portion 412 (in this embodiment the circular recess 419 '), whenever the circular edge of the central portion 412 is in alignment with respective outer edges of the central portions 233, 234 of the backplate 230, and whenever the positioner element is not situated at the center of the central portion 412. However, the use of two positioner elements, as in the embodiment shown in the figures, makes it easier to position the central portion 412 on the tool 600, and thus on the backplate

230 positioned beforehand on the tool 600 as explained above. Before positioning the central portion 412 on the tool 600, the central portions 233, 234 of the front face of the backplate 230 can be covered with a suitable adhesive, so that by placing the central portion 412 on the tool 600, it is possible to bond the central portion 412 adhesively on the backplate 230 (possibly by applying pressure on the front face of the central portion 412). The single positioning of the peripheral portion 411 on the tool 600 and the single positioning of the central portion 412 on the same tool 600 make it possible to obtain the desired relative positioning between the central portion 412 and the peripheral portion 411, and thus to provide continuity of the pattern presented by their respective front faces, as can be seen in Figure 10.

Claims

CLAIMS:

1. A trim unit for an electrical switch comprising a trim

plate having a peripheral portion that is provided with a

central recess defined by an inner edge of said peripheral

portion, wherein the trim plate includes a central portion

that is arranged in the central recess and that is

surrounded by a gap defined between the outer edge of the

central portion and the inner edge of the peripheral portion

so as to receive a control member of the electrical switch

surrounding the central portion.

2. A trim unit according to claim 1, wherein the central

portion and the peripheral portion are mounted on a first

portion and a second portion respectively of a front face of

a backplate, and wherein the first portion and the second

portion are interconnected by at least one bridge that is

situated at the rear of the backplate.

3. A trim unit according to claim 2, wherein the bridge

includes two side portions that extend rearwards

respectively from the first portion and from the second

portion, and that form between them a gap for receiving the

control member.

4. A trim unit according to any one of claims 1 to 3,

wherein the rear face of the trim plate carries positioner

means that ensure determined relative positioning of the

central and peripheral portions of the trim plate.

5. A trim unit according to claim 4, wherein said

positioner means comprise keying means that are arranged in

an asymmetric pattern both on the central portion and on the peripheral portion of the trim plate, and that are adapted to co-operate with counterparts that are provided on a backplate or on a tool.

6. A trim unit according to claim 5, wherein the keying

means are housings that are recessed in the rear face of the

central and peripheral portions.

7. A trim unit according to any one of claims 1 to 6,

wherein the outer edge of the central portion has a shape

that is circular.

8. A trim unit according to any one of claims 1 to 6,

wherein the outer edge of the central portion has a shape

that is rectangular or square.

9. A trim unit according to any one of claims 1 to 8,

including the control member.

10. A method of assembling a trim unit for an electrical

switch including a trim plate, the method comprising the

following steps: • cutting a central portion and a peripheral portion of

the trim plate out from a block of material, the peripheral

portion being provided with a central recess defined by an

inner edge of said peripheral portion; and - assembling the central portion and the peripheral

portion in such a manner as to form a gap between the outer

edge of the central portion and the inner edge of the

peripheral portion, the gap being for receiving a control

member of the electrical switch.

11. An assembly method according to claim 10, comprising a

step of mounting the central portion and the peripheral

portion on a first portion and a second portion respectively

of a front face of a backplate, the first portion and the

second portion being interconnected by at least one bridge

that is situated at the rear of the backplate.

12. An assembly method according to claim 11, wherein the

mounting step comprises the following sub-steps performed in

this order:

• mounting the central portion on the first portion;

- mounting the control member on the backplate; and

- mounting the peripheral portion on the second

portion.

13. An assembly method according to claim 11 or claim 12,

wherein the mounting step comprises the following sub-steps:

• placing the backplate on a tool; and

- placing the trim plate on the backplate in such a

manner that positioner means of the trim plate co-operate

with complementary elements of the tool.

14. An assembly method according to claim 13, wherein the

positioner means comprise at least one housing formed in the

rear face of the central portion or of the peripheral

portion.