GB2165696A - Keyboards - Google Patents

Abstract

A keyboard is covered by a close-fitting film 20 of flexible material, conforming to the contours of the fret 10 and keys 12 of the keyboard without affecting the normal tactile operation of the keys. The film 20 is applied by vacuum-forming on the keyboard itself and prevents water, sand or other foreign bodies entering through the spaces around the keys. <IMAGE>

Description

SPECIFICATION Sealed keyboard This invention relates to a keyboard for a portable computer or other apparatus.

Portable computers and other apparatus with keyboards are now in widespread use in the field, and therefore require protection against water, sand or other foreign bodies entering the apparatus through the spaces surrounding the movable keys. It is now known to provide a rubber membrane underlying the fret which receives the keys, the keys being attached to one side of this membrane and (upon depression) serving to displace respective contact elements, which are on the other side of the membrane, into contact with the underlying printed circuit board. This membrane thus prevents water or other substances entering the apparatus, but does not prevent water or sand or other foreign bodies passing down the sides of the keys, the water possibly freezing and the sand or other foreign bodies possibly otherwise causing the keys to jam.

In accordance with this invention, there is provided a keyboard which is covered by a close-fitting film of flexible material, conforming to the contours of the fret and keys of the keyboard without affecting the normal tactile operation of the keys. Conveniently the protective film is applied by vacuum forming.

In this arrangement, the protective film prevents any water, sand or other foreign bodies even entering the spaces around the keys, so that the possibility is eliminated of the keys jamming from freezing water or sand etc.

An embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawing, the single figure of which is a sectional view of a portion of a keyboard.

In the example shown, the keyboard comprises a fret 10 with apertures in which respective keys 12 are disposed. A rubber membrane 14 underlies the fret and the keys are attached to the upper surface of membrane 14. Each key is depressible (through about 2 mm) against the resilience of the rubber membrane, to displace a contact element 16 (which is mounted on the lower surface of the membrane opposite the respective key) into contact with a printed circuit board 18 which underlies the membrane.

The keyboard assembly is covered by a close-fitting film 20 of flexible material, which in this case is transparent, conforming to the contours of the fret and keys. This protective film does not affect the normal tactile operation of the keys, but does prevent any water, sand or other foreign bodies passing into the spaces around the individual keys.

Preferably the film 20 is applied by vacuum forming so as to ensure a close and exact fit.

Preferably the keyboard assembly (of fret, keys and rubber membrane) is placed on a larger sheet of card, then the film 20 is applied (by vacuum forming) over the keyboard and the card. Then, the keyboard is cut away from the card by severing the vacuum-formed film around the periphery of the keyboard.

Preferably the protective film is not removed from the keyboard, and the keyboard is ready to be assembled into the case of the apparatus: such a case is shown at 22 with fixing for keyboard at 24.

In the example shown, surlin film was used, its thickness being 75 microns before the vacuum forming, and was found to withstand 106 depressions of the keys.

1. A keyboard comprising a plurality of resiliently depressible keys located within respective, conforming apertures of a supporting fret, and a close-fitting film of flexible material covering the keyboard, said close-fitting film being shaped in-situ to conform to the contours of the fret and keys of the keyboard without affecting the normal tactile operation of the keys.

2. A keyboard as claimed in claim 1, in which the close-fitting flexible film is vacuum formed onto said keyboard.

3. A keyboard substantially as herein described with reference to the accompanying drawing.

4. A method of applying a sealed, protective cover to a keyboard which comprises a plurality of resiliently depressible keys within respective apertures of a supporting fret, said method comprising placing a sheet of flexible film over the keyboard, then forming said film to a close-fitting relation with the keyboard, so as to conform to the contours of the fret and keys of the keyboard with affecting the normal tactile operation of the keys.

5. A method as claimed in claim 4, in which said film is formed to said close-fitting relation with the keyboard by vacuum-forming.

6. A method as claimed in claim 5, in which the keyboard is placed on a card of larger size, then the film is applied by vacuum forming to cover the keyboard and surrounding margin of the card, and then the covered keyboard is cut from the card by severing the vacuum-formed film around the periphery of the keyboard.

7. A method as claimed in claim 4, in which the keyboard is assembled into its intended apparatus without at any time removing the formed covering film.

8. A method as claimed in claim 4, and substantially as herein described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Sealed keyboard This invention relates to a keyboard for a portable computer or other apparatus. Portable computers and other apparatus with keyboards are now in widespread use in the field, and therefore require protection against water, sand or other foreign bodies entering the apparatus through the spaces surrounding the movable keys. It is now known to provide a rubber membrane underlying the fret which receives the keys, the keys being attached to one side of this membrane and (upon depression) serving to displace respective contact elements, which are on the other side of the membrane, into contact with the underlying printed circuit board. This membrane thus prevents water or other substances entering the apparatus, but does not prevent water or sand or other foreign bodies passing down the sides of the keys, the water possibly freezing and the sand or other foreign bodies possibly otherwise causing the keys to jam. In accordance with this invention, there is provided a keyboard which is covered by a close-fitting film of flexible material, conforming to the contours of the fret and keys of the keyboard without affecting the normal tactile operation of the keys. Conveniently the protective film is applied by vacuum forming. In this arrangement, the protective film prevents any water, sand or other foreign bodies even entering the spaces around the keys, so that the possibility is eliminated of the keys jamming from freezing water or sand etc. An embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawing, the single figure of which is a sectional view of a portion of a keyboard. In the example shown, the keyboard comprises a fret 10 with apertures in which respective keys 12 are disposed. A rubber membrane 14 underlies the fret and the keys are attached to the upper surface of membrane 14. Each key is depressible (through about 2 mm) against the resilience of the rubber membrane, to displace a contact element 16 (which is mounted on the lower surface of the membrane opposite the respective key) into contact with a printed circuit board 18 which underlies the membrane. The keyboard assembly is covered by a close-fitting film 20 of flexible material, which in this case is transparent, conforming to the contours of the fret and keys. This protective film does not affect the normal tactile operation of the keys, but does prevent any water, sand or other foreign bodies passing into the spaces around the individual keys. Preferably the film 20 is applied by vacuum forming so as to ensure a close and exact fit. Preferably the keyboard assembly (of fret, keys and rubber membrane) is placed on a larger sheet of card, then the film 20 is applied (by vacuum forming) over the keyboard and the card. Then, the keyboard is cut away from the card by severing the vacuum-formed film around the periphery of the keyboard. Preferably the protective film is not removed from the keyboard, and the keyboard is ready to be assembled into the case of the apparatus: such a case is shown at 22 with fixing for keyboard at 24. In the example shown, surlin film was used, its thickness being 75 microns before the vacuum forming, and was found to withstand 106 depressions of the keys. CLAIMS

1. A keyboard comprising a plurality of resiliently depressible keys located within respective, conforming apertures of a supporting fret, and a close-fitting film of flexible material covering the keyboard, said close-fitting film being shaped in-situ to conform to the contours of the fret and keys of the keyboard without affecting the normal tactile operation of the keys.

2. A keyboard as claimed in claim 1, in which the close-fitting flexible film is vacuum formed onto said keyboard.

3. A keyboard substantially as herein described with reference to the accompanying drawing.

4. A method of applying a sealed, protective cover to a keyboard which comprises a plurality of resiliently depressible keys within respective apertures of a supporting fret, said method comprising placing a sheet of flexible film over the keyboard, then forming said film to a close-fitting relation with the keyboard, so as to conform to the contours of the fret and keys of the keyboard with affecting the normal tactile operation of the keys.

5. A method as claimed in claim 4, in which said film is formed to said close-fitting relation with the keyboard by vacuum-forming.

6. A method as claimed in claim 5, in which the keyboard is placed on a card of larger size, then the film is applied by vacuum forming to cover the keyboard and surrounding margin of the card, and then the covered keyboard is cut from the card by severing the vacuum-formed film around the periphery of the keyboard.

7. A method as claimed in claim 4, in which the keyboard is assembled into its intended apparatus without at any time removing the formed covering film.

8. A method as claimed in claim 4, and substantially as herein described with reference to the accompanying drawing.