Pushbutton plate and touch panel

Abstract

Push button plate (18) with at least one convex reaction surface (34a-d) configured to be bent in a predetermined pressure direction (32), the push button plate (18) comprising: a first electrode (36) which is arranged on a convex surface of the reaction surface (34a-d); a second electrode (40) which is arranged in the reaction surface (34a-d) below the first electrode (36) with respect to the pressure direction (32) and is electrically connected to the first electrode (36) by a wire (38); and a third electrode (42) which is arranged on a different section of the push-button plate (18) than the reaction surface (34a-d), wherein the second electrode (40) and the third electrode (42) are configured to be electrically connected to each other when the reaction surface (34a-d) is bent in the pressure direction (32).

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present invention relates to a push button sheet and a touch panel with the push button sheet. 2. Description of the related technology

[0002] In a touch panel used in a mobile device, etc., a dome-shaped, convex part can be arranged on a surface of the touch panel so that an operator can touch a predefined position on the touch panel without looking at the touch panel (e.g., see JP 2011 - 086 491 A, JP 2012 - 195 254 A and JP H09 - 017 278 A).

[0003] On the other hand, it is a known technique to place an operating button outside of a display (or detection area) of a touch panel and to place a detection electrode electrically connected to the operating button in the detection area, so that the actuation of the operating button is recognized as actuation of the detection electrode (e.g. see JP 2017 - 021 471 A).

[0004] During a robot's learning process, an operator often uses a handheld programming device while watching the robot. In such cases, the operator must determine the position of a button on the programming device solely by touch. Similarly, with a dedicated programming device, the operator can determine the button's position by touch alone if the button is configured as a convex part. However, according to current technology, a convex button is often activated not only by touch but also by pressing down on it.

[0005] If, however, a standard mobile device (e.g., a tablet) with a flat touchscreen is used as a programming handheld, the operator cannot determine the button's position by touch. Although a programming handheld may have the function of vibrating when the operator touches a predefined position on the hanger, the operator cannot feel the vibration if wearing gloves, etc.

[0006] Alternatively, the button can be configured to respond when the operator merely touches it. However, in such a case, the operator may accidentally press the button. Although the sheet with the convex part of the push button can be placed on the tablet so that the tablet responds when the button is pressed, the sheet with the convex part can obstruct the use of the tablet for purposes other than teaching, making it necessary to remove the sheet with the convex part.

[0007] US 2011 / 0089011A1 describes a switch module. The switch module is positioned opposite a keypad area. The switch module comprises a transparent FPC board, a transparent conductive film, an electrode, a metal dome that is in contact with a portion of the transparent conductive film and can come into contact with the electrode through deformation, and an LED. Light emitted by the LED and directed perpendicular to the thickness of the transparent FPC board is reflected by a reflective area on the transparent FPC board toward the keypad area. SUMMARY OF THE INVENTION

[0008] The present invention relates to a snap fastener plate according to claim 1. Claims 2 to 6 describe particularly advantageous embodiments of the snap fastener plate according to claim 1.

[0009] One aspect of the present disclosure is a snap-button plate with at least one convex reaction surface configured to be bent in a predetermined pressure direction, the snap-button plate comprising: a first electrode arranged on a convex surface of the reaction surface; a second electrode arranged in the reaction surface below the first electrode with respect to the pressure direction and electrically connected to the first electrode; and a third electrode arranged on a different section of the snap-button plate than the reaction surface, the second electrode and the third electrode being configured to be electrically connected to each other when the reaction surface is bent in the pressure direction.

[0010] Another aspect of the present disclosure is a touch panel with a push-button plate. BRIEF DESCRIPTION of the DRAWINGS

[0011] The above-mentioned and other objectives, features and advantages of the present invention are made clearer by the following description of preferred embodiments of this invention with reference to the accompanying drawings, wherein: Fig. Figure 1 is a view showing a structural example of a touch panel with a push-button plate according to the present disclosure; Fig. Figure 2 is a schematic configuration view of the push button plate; Fig. Figure 3 is a view showing another structural example for each reaction surface of the push-button plate; Fig. Figure 4a is a view that explains an example of a recognition result of the touch panel when a user touches a specific response area of ​​the push button plate; Fig. Figure 4b is a view that explains an example of a recognition result of the touch panel when the user touches a specific response area of ​​the push button plate; Fig. 5 is a view that schematically shows a position and electrical connection relationship of electrodes in a multitude of reaction surfaces; Fig. Figure 6a is a perspective view showing a preferred example of an electrode structure; Fig. Figure 6b is a side view showing a preferred example of an electrode structure; Fig. Figure 7a is a view showing an example of a structure to prevent an incorrect response from the touch panel; Fig. Figure 7b is a view that shows another example of the structure to avoid an incorrect response from the touch panel; Fig. Figure 8a is a perspective view showing another preferred example of an electrode structure; Fig. Figure 8b is a side view showing another preferred example of the electrode structure; Fig. Figure 9a is a view showing a preferred example of the shape of the electrode in one pressure direction; Fig. Figure 9b is a view showing another preferred example of the shape of the electrode in the direction of pressure; Fig. Figure 9c is a view showing another preferred example of the shape of the electrode in the direction of pressure; and Fig. Figure 10 shows an application example for the touch panel with the push button plate. DETAILED DESCRIPTION

[0012] Fig. Figure 1 is a schematic representation of a mobile device (tablet) 10 according to a preferred embodiment. The tablet 10 has a main body 12, a display section 14, such as an LCD, attached to the main body 12, a touch panel 16 overlapping at least a portion of the display section 14, a push-button panel 18 attached to at least a portion of the surface of the touch panel 16 (in this case, on it), and a control section 20, such as a processor configured to perform various processes (e.g., displaying a predetermined image on the display section 14) depending on an operation (touching or pressing, etc.) by an operator (user) on the touch panel 16 or the push-button panel 18. In this respect, the aforementioned components, with the exception of the push-button panel 18, can be the same as conventional components.

[0013] Fig. Figure 2 is a side cross-section showing a schematic configuration of the touch panel 16 and the push-button plate 18 mounted on the touch panel 16. For example, the touch panel 16 can be a capacitive touch panel of the surface or projection type, having a laminated structure consisting of a protective cover 22, a transparent electrode membrane or electrode pattern layer 24, and a glass substrate 26. The touch panel 16 can detect where on the touch panel 16 an operator's finger touches or approaches it (i.e., a touch position) by measuring a change in capacitance through a sensor, etc., when the operator's finger touches or approaches the touch panel 16. Furthermore, a touch panel of the resistive membrane type, etc., where the operator must physically deform the surface of the touch panel (the conductive object), can be excluded as a possible touch panel 16 of the embodiment.

[0014] The push-button plate 18 has: a (preferably transparent) plate element 28, such as a soft resin, which has some flexibility and adhesion; and a conductive element (electrode) 30, which is made of conductive material, such as metal, to enable single and multiple scanning as described below. The plate element 28 has at least one convex reaction surface which is bendable in a predetermined pressure direction (in this case, a direction that is generally perpendicular to the plate surface or to the surface of the touch panel 16) 32. As shown in Fig. As shown in Figure 1, in this embodiment four hollow, convex sections 34a to 34d are formed as the first to fourth reaction surfaces.

[0015] As a conductive element 30, at least one of the hollow convex sections (in the drawing, the hollow convex section 34a) has: a first electrode (layer) 36, which is arranged on a convex surface (specifically, an upper surface of the convex section) of the reaction surface 34a; and a second electrode (layer) 40, which is arranged within the reaction surface 34a and below the first electrode 36 with respect to the pressure direction 32 (specifically, a lower surface of the plate element 28) and is electrically connected to the first electrode 36 by a transparent wire or an extra-thin wire 38, etc., which is not visible to the naked eye. Therefore, if the finger, etc.When the operator's finger comes into contact with or near the first electrode 36, the second electrode 40 reacts electrically (specifically, static electricity from the surface of the touch panel 16 flows via the first electrode 36 and the second electrode 40 to the operator's finger, or the electrostatic capacitance between the touch panel 16 and the second electrode 40 is changed). This alters the electrostatic capacitance of the touch panel 16, and the same effect can then be achieved as if the operator touched or approached a section of the touch panel 16 directly below the reaction area 34a. A protective film can be placed on the first electrode 36; this protective film is not shown.

[0016] The push-button plate 18 has a third electrode 42, which is arranged on a different section of the push-button plate 18 than the reaction surface 34a (in this case, within a second reaction surface 34b), and the second electrode 40 and third electrode 42 are configured to be in contact (electrically connected) with each other when the convex surface (or the first electrode 36) of the reaction surface 34a is pressed in the pressure direction 32. Specifically, a fourth electrode 46 is further arranged within the first reaction surface 34a between the first electrode 36 and the second electrode 40, and the fourth electrode 46 is electrically connected to the third electrode 42 by an extra-thin wire 44, etc. The fourth electrode 46 is configured to come into contact with the second electrode 40 when the reaction surface 34a is pressed and bent in the pressure direction 32.Therefore, when the fourth electrode 46 comes into contact with the second electrode 40, a static electricity flows via the third electrode 42 and the fourth electrode 46 from the surface of the touch panel 16 to the operator's finger (or an electrostatic capacitance of the touch panel surface is changed), producing the same effect as if the operator were to touch or approach a section of the touch panel 16 directly below the reaction area 34b.

[0017] In the example of Fig. 2. Each reaction surface (or the hollow convex section) is configured as a hemispherical (dome-shaped) form, each of the first, second, third, and fourth electrodes is configured as a conductive layer (electrode layer), and the first electrode 36 and the fourth electrode 46 are configured on the outer (front) surface and the inner (back) side, respectively, of the plate element that forms the convex section of the first reaction surface 34a. However, the structure of the electrodes is not limited to the structure as such. For example, as in Fig. 3 shown, each reaction surface (only the first reaction surface 34a is in Fig. 3 shown) can be formed as a prismatic or columnar shape which can be bent in the pressure direction 32, and a circumferential edge of the fourth electrode 46 can be supported by the plate element 28 within the reaction surface 34a.

[0018] Fig. 4a explains an example of a recognition result of touch panel 16 when the operator contacts (or touches) the first response surface 34a, and Fig. 4b explains the recognition result when the operator then presses the first reaction surface 34a. As in Fig. As shown in 4a, when the operator's finger 48 etc. touches the first reaction surface 34a (or the first electrode 36), a state is created in which only a section of the touch panel corresponding to the first reaction surface 34a is touched.

[0019] Next, as in Fig. As shown in Figure 4b, when the operator's finger 48, etc., presses on the first reaction surface (hollow convex section) 34a, causing the hollow convex section to bend, the third electrode 42 within the second reaction surface 34b also reacts electrically as described above, and a state is then established in which two touch panel areas, corresponding to the first reaction surface 34a and the second reaction surface 34b respectively, are being touched. Thus, in this embodiment, different results of touch input can be achieved by touching the reaction surface and pressing the same reaction surface.

[0020] In this disclosure, an operation in which only the portion of the touch panel corresponding to the operator's contacted response area responds (is recognized as input), as if the operator were touching the first electrode 36 (and not pressing the hollow convex section 34a by a certain volume), is referred to as a "single-tap." Furthermore, an operation in which not only the portion of the touch panel corresponding to the operator's contacted response area, but also another portion of the touch panel (in this case, the second response area 34b) responds, as if the operator were pressing the hollow convex section 34a by a certain volume in the direction of pressure 32, is referred to as a "multi-tap." Therefore, the single-tap can occur if the operator touches any response area, but the multi-tap occurs only if the operator presses any response area downwards.

[0021] In this disclosure, one side of the push button plate attached to the touch panel is referred to as the “bottom side (or bottom surface)” and the opposite side of the push button plate is referred to as the “top side (or top surface)”.

[0022] Fig. Figure 5 explains an application example of the aforementioned Multi-Tap and schematically shows the position and electrical connection (or wiring) of the electrodes in four reaction surfaces 34a to 34d. In this example, the first electrode 36, the fourth electrode 46, and the second electrode 40 can also be referred to as the A-layer, B-layer, and C-layer, respectively, and the reaction surfaces 34a to 34d have the same electrode structure.

[0023] As with reference to Fig. As explained in section 2, the B-layer of the first reaction surface 34a is electrically connected to the C-layer of the second reaction surface 34b. Therefore, when the first reaction surface 34a is pressed, the C-layer of the first reaction surface 34a is electrically connected to the C-layer of the second reaction surface 34b, and the Multi-Tap, as shown in [reference missing], [action missing]. Fig. As shown in Figure 4b, this can be realized. Similarly, the B-layer of the second reaction surface 34b is electrically connected to the C-layer of the third reaction surface 34c. Thus, when the second reaction surface 34b is pressed, the C-layer of the second reaction surface 34b is electrically connected to the C-layer of the third reaction surface 34c, and the multi-tap can be realized.

[0024] Furthermore, the B-layer of the third reaction surface 34c is electrically connected to the C-layer 40 of the first reaction surface 34a. Therefore, when the third reaction surface 34c is pressed, the C-layer of the third reaction surface 34c is electrically connected to the C-layer of the first reaction surface 34a, and the multi-tap can be realized. Additionally, the B-layer of the fourth reaction surface 34d is electrically connected to the C-layer 42 of the second reaction surface 34b. Therefore, when the fourth reaction surface 34d is pressed, the C-layer of the fourth reaction surface 34d is electrically connected to the C-layer of the second reaction surface 34b, and the multi-tap can be realized.

[0025] If the operator in the example of Fig. If only a specific response area is touched, only the section of the touch panel corresponding to that specific response area is recognized as the touch position (the single tap). However, if the specific response area is pressed and bent, the sections of the touch panel corresponding to multiple response areas, including the pressed response area, are recognized as touch positions (the multi-tap). In the example of Fig. When a reaction surface is pressed, the multi-tap is performed with respect to two reaction surfaces. However, depending on the wiring between the electrodes, the multi-tap can be performed with respect to three or more reaction surfaces when a reaction surface is pressed.

[0026] Fig. 6a and Fig. Figure 6b schematically shows a preferred example of the electrode structure. Fig. 6a is a perspective view of layers A to C, and Fig. Figure 6b is a side view of the layers. As described above, the operator intends to perform the single tap by touching only the first electrode (or layer A) of the designated reaction area. Therefore, it is undesirable for the fourth electrode (or layer B), which is connected to the electrode of the other reaction area, to react electrically (specifically: layer A touching layer B, static electricity from the touch panel surface flowing through layer B to layer A, or the capacitance between layer A and layer B changing).

[0027] Therefore, as in the Fig. 6a and Fig. As shown in Figure 6b, the fourth electrode 46 is configured and positioned such that it is not present in the rear projection area of ​​the first electrode 36 with respect to the pressure direction 32. Thus, by determining the shapes and positions of the first electrode 36 and the fourth electrode 46, it is possible to prevent the first electrode 36 (the A-layer) from coming into contact with the fourth electrode 46 (the B-layer), even if the first electrode 36 is moved in the pressure direction 32. Furthermore, the distance between the first electrode 36 and the fourth electrode 46 can be extended as much as possible, thereby preventing current from flowing via the B-layer (the fourth electrode) to the A-layer (the first electrode) (i.e., the false detection that the second reaction surface 34b is being touched) when the operator touches the first electrode 36.

[0028] On the other hand, the second electrode 40 is configured and positioned such that at least part of the second electrode 40 is located in a lower projection area of ​​the fourth electrode 46 (in the drawing, a lower projection area of ​​both the first electrode 36 and the fourth electrode 46) with respect to the pressure direction 32. By determining the shapes and positions of the second electrode 40 and the fourth electrode 46, the B layer (fourth electrode 46) can reliably come into contact with the C layer (second electrode 40) (i.e., the multi-tap can be performed) when the first reaction surface 34a is pressed.

[0029] Fig. 7a and Fig. Figure 7b shows another example of the reaction surface structure to prevent the fourth electrode (the B layer) and the other electrode electrically connected to the fourth electrode from triggering a reaction when the operator touches the first electrode (the A layer). In the example of Fig. 7a The first electrode 36 and the fourth electrode 46 are arranged on the front and back sides of a section (or a convex upper section) 50 of the plate element 28, and the thickness (or the distance in the pressure direction) of the section 50 is greater than in the example of Fig. 2, which prevents false detection when the operator touches the first electrode 36.

[0030] As in Fig. As shown in Figure 3, the fourth electrode 46 can be separated from the back of the convex upper section, so that an air layer 52 is formed between the first electrode 36 and the fourth electrode 46. This also prevents false detection when the operator touches the first electrode 36.

[0031] Furthermore, as in Fig. As shown in Figure 7b, a spacer (in the drawing, a layer) 54 is positioned between the first electrode 36 and the fourth electrode 46 (in the drawing, between the first electrode 36 and the plate element 28 (or the convex surface)). This spacer is made of a material such as polyimide, fluorine-based resin, or epoxy resin with a lower dielectric constant than the material forming the plate element 28. This also prevents false detection when the operator touches the first electrode 36. On the other hand, a high-dielectric element, such as that used in a conventional capacitor, is not preferable because such an element can transmit the contact of the finger (or the change in electrical charge).Therefore, at least one of the shape, size, and material of the object located between the first electrode 36 and the fourth electrode 46 can be chosen or determined such that the fourth electrode 46 does not react electrically (specifically, the static electricity of the touch panel surface is not absorbed by the finger from the first electrode 36 via the fourth electrode 46, etc., or the electrostatic capacitance between the first electrode 36 and the fourth electrode 46 is not changed) when an operator touches the first electrode. This prevents the occurrence of multi-tap when the operator only touches the first electrode 36.

[0032] Fig. 8a and Fig. Figure 8b schematically shows another preferred example of the electrode structure. Fig. Figure 8a is a perspective view of layers A to C, and Fig. Figure 8b is a side view of the layers. In this example, the second electrode 40 (the C layer) has a first electrode piece 40a, which is electrically connected to the first electrode 36 (the A layer) by an extra thin wire 38, etc., and a second electrode piece 40b, which is connected to the electrode of the other reaction surface (e.g., the third electrode 42, as in Figure 8b). Fig. 2 shown) is electrically connected by an extra thin wire 44, etc. The fourth electrode 46 (the B-layer) is configured such that the first electrode piece 40a is electrically connected to the second electrode piece 40b when the reaction surface 34a is pressed and bent in the pressure direction 32.

[0033] Specifically, the fourth electrode 46 is configured and positioned such that at least part of it is located in the forward projection area of ​​both the first electrode piece 40a and the second electrode piece 40b with respect to the pressure direction 32. By determining the shapes and positions of the second electrode 40 and the fourth electrode 46, the B-layer (fourth electrode 46) can contact both the first electrode piece 40a and the second electrode piece 40b, thus electrically connecting the electrode pieces and enabling the multi-tap to be performed when the first reaction surface 34a is pressed. Since the fourth electrode is not electrically connected to the other electrode, no change in capacitance with respect to the fourth electrode 46 (i.e., the multi-tap) occurs even if the operator touches the first electrode 36.

[0034] As in Fig. 6a or Fig. As shown in Figure 8a, to ensure the transparency of the push-button plate, it is preferable that each layer of a reaction surface (in this case the first reaction surface 34a) has a plurality of (five in the drawing) electrodes (or electrode pieces).

[0035] Fig. Figures 9a to 9c show a preferred example of the electrode shape, viewed in the pressure direction of the reaction surface. In the example of Fig. 6a (6b) Each of the electrodes corresponding to the A-layer, the B-layer and the C-layer has a round shape, and the A-layer and the B-layer are contained within the C-layer when viewed (from above) in the direction of pressure 32, as shown in Fig. 9a shown.

[0036] However, the electrode structure is not limited to this. For example, as in Fig. As shown in 9b, each of the electrodes corresponding to the A-layer, the B-layer and the C-layer has a rod shape or a rectangular shape, and the C-layer can be partially overlapped with the A-layer and the B-layer when viewed (from above) in the direction of pressure 32.

[0037] Alternatively, as in Fig. As shown in Figure 9c, each of the electrodes corresponding to the A-layer, B-layer, and C-layer has a mesh shape consisting of extra-thin wires, and the C-layer can partially overlap with the A-layer and B-layer when viewed (from above) in the direction of pressure 32. Thus, each electrode can have any shape and structure as long as the single tap and the multiple tap, as explained above, can be realized.

[0038] Fig.Figure 10 shows an application example for the touch panel with the push-button sheet according to the present disclosure. In this example, a mobile terminal 10, such as a tablet, with the touch panel 16 is used as a programming handheld device for teaching a multi-joint robot 56 via wireless communication, etc. The robot 56 has a movable part 58, such as a hand, which is configured to move and rotate with respect to three mutually orthogonal drive axes (X, Y, Z).

[0039] The touch panel 16 has six touch switches 60 (X+, X-, Y+, Y-, Z+, Z-) for moving the movable part 58 along the X, Y, and Z axes of the robot 56 and six touch switches 62 (X+, X-, Y+, Y-, Z+, Z-, to which an arc is added) for rotating the movable section 58 about the X, Y, and Z axes of the robot 56. When the push button plate 18 with twelve reaction surfaces (the hollow, convex parts) is applied to the touch panel 16, each of the push buttons 60 and 62 functions as a push button capable of single-tap and multi-tap operation.

[0040] For example, if the operator touches the X button while searching for its position by touch alone, the robot's movable part 58 will not move. Conversely, if the operator presses the X+ button, the movable part 58 can only be moved in the + direction along the X-axis. This prevents operator error if the operator accidentally touches the response surface. Even if the mobile terminal 10 is used for a different purpose (e.g., for editing a browser or text) than the programming handheld, the mobile terminal can still be used while the push-button plate 18 is placed on the touch panel 16. For example, if a browser link displayed on the response surface 34a is tapped only once, without pressing the response surface 34a, operation can be performed similarly to when the push-button plate 18 is not in use.In other words, if the tablet is not used as a programming handheld device, the effort of removing the push-button plate from the tablet can be saved.

[0041] As described above, by using the push-button plate 18 of the present disclosure in the touch panel 16, different input results can be achieved between the time the operator touches the button and the time the operator presses the same button, thus enabling different inputs compared to the prior art. Furthermore, by appropriately selecting the material of the push-button plate 18 (plate element 28), the plate can be easily attached to or detached from the touch panel 16. Therefore, even if the touch panel 16 is a commercial product, a user-friendly touch panel can be provided depending on its intended use.

[0042] According to the present disclosure, the various input results can be achieved between the time the operator touches the response area of ​​the push-button panel and the time the operator presses the same response area, and the various input results can be achieved even if the number of response areas is relatively small. Furthermore, depending on the setting of the touch panel, an operator error that could occur if the operator accidentally touches the response area can be avoided.

Claims

[1] Push button plate (18) with at least one convex reaction surface (34a-d) configured to be bent in a predetermined pressure direction (32), the push button plate (18) comprising: a first electrode (36) which is arranged on a convex surface of the reaction surface (34a-d); a second electrode (40) which is arranged in the reaction surface (34a-d) below the first electrode (36) with respect to the pressure direction (32) and is electrically connected to the first electrode (36) by a wire (38); and a third electrode (42) which is arranged on a different section of the push-button plate (18) than the reaction surface (34a-d), wherein the second electrode (40) and the third electrode (42) are configured to be electrically connected to each other when the reaction surface (34a-d) is bent in the pressure direction (32). [2] Push button plate (18) according to claim 1, further comprising a fourth electrode (46) arranged between the first electrode (36) and the second electrode (40) and electrically connected to the third electrode (42), wherein the fourth electrode (46) is configured to come into contact with the second electrode (40) when the reaction surface (34a-d) is bent in the pressure direction (32). [3] Push button plate (18) according to claim 2, wherein the fourth electrode (46) is positioned such that the fourth electrode (46) is not contained in a lower projection area of ​​the first electrode (36) with respect to the pressure direction (32). [4] Push button plate (18) according to claim 2 or 3, wherein at least one shape, size and material of an object located between the first electrode (36) and the fourth electrode (46) is determined such that an electrostatic capacitance between the first electrode (36) and the fourth electrode (46) is not changed when an operator touches the first electrode (36). [5] Push button plate (18) according to claim 1, further comprising a fourth electrode (46) arranged between the first electrode (36) and the second electrode (40), wherein the second electrode (40) has a first electrode piece (40a) which is electrically connected to the first electrode (36) and a second electrode piece (40b) which is electrically connected to the third electrode (42) and not electrically to the first electrode (36), and wherein the fourth electrode (46) is configured to electrically connect the first electrode piece (40a) to the second electrode piece when the reaction surface (34a-d) is bent in the direction of pressure (32). [6] Push button plate (18) according to any one of claims 2 to 5, wherein the first electrode (36) is formed on an outer surface of a convex section of a plate material which forms a hollow convex part which defines the reaction surface (34a-d), and the fourth electrode (46) is formed on an inner surface of the convex section. [7] Touch panel (16) comprising the push button plate (18) of any one of claims 1 to 6.

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