A vandal-proof hermetically sealed keyboard

Abstract

 Described herein is a vandal-proof hermetically sealed keyboard (1) having a printed circuit (3), a plurality of keys (4) arranged on the printed circuit (3), and a metal plate (5) for protecting the printed circuit (3), a mat (6) made of rubbery material being set between the circuit (3) and the metal protective plate (5) and being provided with a plurality of mobile shaped portions (9), which each define the keys (4), and which engage slidably in respective guide seats (8) made through the protective plate (5).

Description

[0001] The present innovation relates to a vandal-proof hermetically sealed keyboard.

[0002] From the European patent No. EP 0 585 536 there is known a vandal-proof hermetically sealed keyboard comprising a printed circuit, a plurality of snap-action actuators arranged on the printed circuit, and, for each actuator, a respective actuating key, which in turn comprises an external body surrounded by a metal outer surface plate and an internal body, which operatively faces the corresponding actuator.

[0003] The keyboard described in the European patent cited above moreover comprises an internal crush-proof layer provided with a plurality of through seats, which each receive a corresponding internal body and an elastic membrane, which is set between each metal outer surface plate and the crush-proof body and is pressed between the internal and external bodies of each key.

[0004] The hermetically sealed keyboard described above, albeit achieving its purposes with extreme success, has, however, presented production costs that are relatively high, above all on account of the large number of items involved.

[0005] The purpose of the present innovation is to provide a hermetically sealed keyboard, which will be free from the drawbacks described above and will be] inexpensive and simple to build.

[0006] According to the present innovation, a hermetically sealed vandal-proof keyboard is provided, which comprises a printed circuit, a plurality of keys arranged on the printed circuit, and a metal plate for protecting the printed circuit, the keyboard being characterized in that it comprises a mat made of rubbery material, which is set between the circuit and the metal protective plate and comprises a plurality of mobile shaped portions, each defining said keys, the protective plate having, for each key, a guide seat slidably engaged by the respective key.

[0007] The innovation will now be described in detail with reference to the attached drawings, which are provided merely by way of non-limiting example and in which:

• Figure 1 is a partial cross-sectional view of a preferred embodiment of the hermetically sealed vandal-proof keyboard built according to the teachings of the present innovation; and
• Figure 2 is a partial cross-sectional view of a second embodiment of the hermetically sealed vandal-proof keyboard of Figure 1.

[0008] With reference to Figure 1, number 1 designates, as a whole, a hermetically sealed vandal-proof keyboard designed, for example, to find application in critical industrial sectors or else in telematic transaction terminals and, in any case, in all those environments for which it is necessary to guarantee operation of the keyboard even following upon possible acts of vandalism.

[0009] The keyboard 1 comprises a printed circuit 3, a plurality of keys 4 (only one of which is illustrated in the figures) arranged on the printed circuit 3, a metal plate 5 for protecting the printed circuit 3 itself, and a mat 6 made of rubbery material, which provides a continuous coating of the circuit 3, and in turn comprises a main body 7, which is set between the circuit 3 and the plate 5 and has a substantially constant thickness S1.

[0010] The plate 5 is made of stainless steel and has, for each key 4, a guide seat 8, which is defined by a through hole passing through the plate 5 itself and is slidably engaged by the respective key.

[0011] The mat 6 comprises a plurality of mobile shaped portions 9, which each define a corresponding key 4, and, for each key 4, a compliant elastic membrane 10 for connection between the main body 7 and the shaped portion 9.

[0012] Each shaped portion 9 has a thickness S2 that is substantially equal to the thickness S1, whilst the corresponding membrane 10 has a thickness S3 that is decidedly smaller than the thickness S2, but sufficient for bestowing on the membrane 10 itself an elasticity and a stiffness such as to enable, upon each manual pressure exerted on the corresponding key 4, return of the latter into a raised resting position.

[0013] Each shaped portion 9 is moreover coated on the outside with a respective coating cap 11, made of stainless steel and provided with an arresting edge, which is designed to co-operate with the seat 8 to prevent any possible extraction of the key 4 from the seat 8 itself. In particular, each cap 11 comprises a plane top wall 13 and an annular wall 14, which delimits peripherally the wall 13 itself and is set around the shaped portion 9. The edge 12 is fixed to the wall 14 and has an external diameter greater than an internal diameter of the seat 8.

[0014] Each wall 13 has a substantially oval shape in order to prevent any rotation of the corresponding cap 11 and is coplanar with an outer surface 15 of the plate 5 when the corresponding key 4 is set in the aforesaid raised resting position. Each wall 13 is, moreover, provided with respective identification wordings 16, which are obtained using a laser beam or by etching, and are filled with transparent and/or coloured resin.

[0015] The keyboard 1 further comprises a plurality of LEDs 17 set beneath each key 4 for lighting up the wordings 16, and a plurality of snap-action plates 18 (just one of which is illustrated), each of which is set vertically beneath the corresponding key 4 and can be activated by pressing the key 4 itself.

[0016] In particular, each plate 18 comprises four lobes 19, which rest on respective fixed electrical contacts 20, which form part of the circuit 3 and are uniformly distributed around an internal electrical contact 21, which can be activated by deformation of the plate 18.

[0017] In the embodiment illustrated in Figure 1, each key 4 is mounted together with the corresponding cap 11 within the corresponding seat 8, and is maintained by the corresponding membrane 10 and the corresponding edge 12 in the aforementioned raised resting position, starting from which, once it has been activated manually, it moves downwards in a direction parallel to its own axis, being guided by the seat 8 in the direction of the corresponding plate 18, on which it acts by means of a central pin 22 axially aligned with the plate 18 itself. The pressure applied precisely in the central point of the plate 18 causes deformation of the plate 18 itself, which comes into contact with the internal contact 21, setting it in electrical contact with the external contacts 20.

[0018] Finally, with the purpose of further protecting the plates 18, the keyboard 1 comprises a substantially continuous layer 23 of covering made of polyester material, which is set between the mat 6, i.e., the corresponding mobile shaped portion 9, and each plate 18, and is rested on a bi-adhesive spacer 24 set right up against the circuit 3.

[0019] The embodiment illustrated in Figure 2 regards a keyboard 1' similar to the keyboard 1, from which it differs above all in that, when each key 4 is set in its raised resting position, the wall 13 is set projecting with respect to the outer surface 15 of the plate 5.

[0020] In addition, the keyboard 1' comprises, for each key 4 and instead of the snap-action plate 18, a fixed electrical path 25, which is set on the printed circuit 3 and has an annular shape, just as each key 4 comprises, instead of the corresponding pin 22, a respective mobile electrical path 26 which is able to move away from and towards the corresponding path 25. Each path 25 comprises a layer 27 of coating made of graphite, an outer ring 28 provided with a plurality of internal radial appendages 29, and an inner ring 30 provided with a plurality of external radial appendages 31, arranged so that they are interspersed with the radial appendages 29.

[0021] Each path 26 has a conformation corresponding to the conformation of the corresponding path 25 and is likewise provided with a respective layer 32 of coating made of graphite so as to ensure at all times contact between the two paths 25 and 26 irrespective of the precision with which the corresponding key 4 is pressed.

[0022] Finally, the keyboard 1' comprises, for each key 4, just one LED 17, which is set within the inner ring 30.

[0023] Furthermore, the keyboard 1' differs from the keyboard 1 in that the membrane 10 of each key 4 has the shape of a truncated cone, so allowing the corresponding key to have a so-called "long" stroke (at least 1.5 mm) and, finally, in that the layer 23 and the spacer 24 are absent.

[0024] It is understood that the innovation is not limited to the embodiments described and illustrated herein, which are to be considered as examples of embodiment of the hermetically sealed keyboard, which may, instead, undergo further modifications regarding the shapes and arrangements of parts and the details of construction and assembly.

Claims

1. A vandal-proof hermetically sealed keyboard (1) (1') comprising a printed circuit (3), a plurality of keys (4) arranged on the printed circuit (3), and a metal plate (5) for protecting the printed circuit (3), the keyboard (1) (1') being characterized in that it comprises a mat (6) made of rubbery material, which is set between the circuit (3) and the metal protective plate (5), and in that it comprises a plurality of mobile shaped portions (9), which each define said keys (4), the metal protective plate (5) having, for each key (4), a guide seat (8) slidably engaged by the corresponding key (4).

2. The keyboard according to Claim 1, characterized in that the mat (6) made of rubbery material coats the printed circuit (3) in a continuous way and comprises a main body (7) , which has a thickness (S1) that is substantially equal to the thickness (S2) of each mobile shaped portion (9), and for each key (4), a compliant elastic membrane (10) forming a connection between the main body (7) and the mobile shaped portion (9) themselves.

3. The keyboard according to Claim 2, characterized in that it comprises, for each key (4), a cap (11) for coating the key (4), said cap (11) being provided with an arresting edge (12), designed to co-operate with the guide seat (8) of the corresponding key (4) in order to prevent any possible extraction of the key (4) from the seat (8) itself.

4. The keyboard according to Claim 3, characterized in that each cap (11) is made of stainless steel and is provided with respective identification wordings (16) obtained by means of a laser beam or by etching, said wordings (16) being filled with transparent and/or coloured resin.

5. The keyboard according to Claim 4, characterized in that the mat (6) made rubbery material is made of transparent silicone rubber.

6. The keyboard according to Claim 5, characterized in that each cap (11) comprises a top portion (13) set coplanar with a top surface (15) of said protective plate (5) with the key (4) set in a raised resting position.

7. The keyboard according to Claim 6, characterized in that it comprises, for each key (4), a snap-action plate (18), which can be actuated by means of pressure exerted by the corresponding key (4), each key (4) comprising a central pin (22) set axially aligned with the corresponding snap-action plate (18).

8. The keyboard according to Claim 7, characterized in that it comprises a substantially continuous covering layer (23), made of polyester material and set between said mat (6) and each snap-action plate (18).

9. The keyboard according to Claim 8, characterized in that each snap-action plate (18) comprise four lobes (19) resting on respective fixed electrical contacts (20), which are uniformly distributed around an internal electrical contact (21), which can be activated by deformation of the snap-action plate (18).

10. The keyboard according to Claim 5, characterized in that each cap (11) comprises a top portion (13) set so that it projects with respect to a top surface (15) of said protective plate (5) for protecting the key (4) set in a raised resting position.

11. The keyboard according to Claim 10, characterized in that it comprises, for each key (4), a fixed electric path (25) set on the printed circuit (3) and having an annular shape, each key (4) comprising a respective mobile electrical path (26) set on an internal face of the corresponding mobile shaped portion (9) and free to move together with the corresponding mobile shaped portion (9) away from and towards the corresponding fixed electrical path (25).

12. The keyboard according to Claim 11, characterized in that the fixed electrical path (25) comprises an outer ring (28) provided with a plurality of internal radial appendages (29) and an inner ring (30) provided with a plurality of external radial appendages (31), which are arranged interspersed with the internal radial appendages (29) of the outer ring (28).

13. The keyboard according to Claim 12, characterized in that each mobile electric path (26) and each fixed electric path (25) comprise a layer (27) (32) of coating made of graphite.

14. The keyboard according to Claim 13, characterized in that it comprises a light source (17), which is set on the inside of the inner ring for lighting up the wordings (16) of the corresponding key (4).

15. The keyboard according to any one of Claims 6 to 14, characterized in that each top portion (13) has a substantially oval shape in order to prevent any rotation of the corresponding cap (11).

16. The vandal-proof hermetically sealed keyboard substantially as described with reference to any one of the annexed drawings.

Drawing