Hermetic sealing structure for electronic keyboard apparatus

Abstract

This disclosure describes an electronic keyboard arrangement which is sealed to prevent the introduction into the internal keyboard electronics of such contaminants as exist in the operating environment. The seal is so constructed as to allow the keyboard switches to operate independently from the seal. The seal is also designed to adapt to varying sizes and shapes of keyboard mounted switch bodies and is adhesively bonded to the interfacing portions of the bodies adjacent to the seal thereby hermetically sealing the area containing electronic components, including switches, from all atmospheric contaminants.

Description

BACKGROUND OF THE INVENTION

This invention relates to keyboards and more particularly to electronic system keyboards.

Historically, electronic keyboards have found application primarily in non-deleterious environments such as offices and environments designed for computer habitation. As electronic keyboards are put to use in increasing numbers in the more harsh environments encountered in factories, it has become desirable to protect the internal keyboard electronics from damage due to liquids, dust, dirt and metal chips. Several keyboard designs providing protection for internal keyboard electronics from harsh environments have been developed over the past decade.

A type of environmental seal design employed is one incorporating the seal into the keyboard switch or key assembly itself. Such environmentally sealed keys are, of course, more expensive than the readily available, standard keys of the nonsealed variety. Also, most are electrical rather than mechanical in nature, providing, upon activation, an increase in inductance or capacitance, for example, giving rise to a pulse representing a struck character. Such electrical keys may be fraught with "bounce" problems so often associated with activation of keys of that type. In addition, keyboards employing such sealed keys are designed to use those unique keys, and therefore, such a sealing system does not possess retrofit capabilities for providing environmental seals to existing keyboard systems, and such a sealing system is not readily adaptable to other keyboard and keyboard switch configurations.

Another type of environmental seal design employed is one which makes use of an impervious membrane in combination with a coordinated key design. Keyboards using this type of seal display excellent sealing characteristics. This type of seal, however, requires the use of specially designed keyboard switches for coordination with the sealing membrane, and in some cases, requires the use of a conductive membrane. Again, such designs are more expensive than the readily available, standard keyboards that do not require keyboard switches coordinated with an environmental seal. As such designs are designed for a particular keyboard switch and membrane combination, they are not easily incorporated in retrofit efforts for providing environmental seals to existing keyboard systems, and are also not readily adaptable to other keyboard and keyboard switch configurations.

A third type of environmental seal design employed is one which utilizes an elastic, impervious membrane which attaches to the keyboard housing and has provisions for extension through the membrane of the keyboard switch keyshafts, providing a seal around the keyshafts while allowing keyboard switch actuation motion of the keyshafts through the membrane. This type of seal design is not expensive in comparison to the other types of seals hereinbefore described, and may be used in connection with standard and readily available keyboard and keyboard switch configurations. This design lends itself to retrofit efforts for providing environmental seals to existing keyboard systems, and is readily adaptable to other keyboard and keyboard switch configurations. One drawback of such a design, however, is that the keyboard switches do not act independently from the membrane, but rather the keyboard switch keyshafts slide through the sealing membrane with keyboard switch actuation. Such sliding action can result in keys sticking in the up or down position, or positions between, and may result in keys that are difficult to depress.

Applicant herein discloses a new type of electronic keyboard seal designed to prevent the entry of liquids, dust, dirt and metal chips onto an internal electronic circuit board. The present invention provides an environmental seal through the use of an elastic, impervious membrane secured to the internal surface of the front cover plate, suspended across all of the openings in the front cover plate, and adhesively bonded to the keyboard switches. This seal is not only inexpensive, but may also be used with standard and readily available keyboard and keyboard switch configurations. It lends itself to retrofit efforts for providing environmental seals to existing keyboard systems, and is readily adaptable to other keyboard and keyboard switch configurations. Furthermore, it overcomes the single drawback of the prior art designs utilizing an elastic impervious membrane in that the membrane in the present invention is secured to the keyboard switch bodies and does not seal around the keyboard switch shafts, thereby allowing the keyboard switches to function independently from the membrane, resulting in no sticking keys or difficult key operation due to interference between the membrane and the keyboard switch shaft.

SUMMARY OF THE INVENTION

The invention consists of an electronic keyboard arrangement which is sealed to prevent the introduction into the internal keyboard electronics of such contaminants as exist in the operating environment, the seal being so constructed as to allow the keyboard switches to operate independently from the seal.

The seal is constructed primarily of a shield, an adhesive for bonding the shield to the keyboard switch bodies, and a retainer for holding the shield in place. The shield consists of a pliable membrane, such as rubber, impervious to dust, dirt, liquids, metal chips and other contaminants that may be encountered in a factory atmosphere, secured to the internal surface of the front cover plate in such a fashion as to shield the electronic circuit board from such contaminants. The membrane is cut to such a size and in such a shape as to be capable of encompassing all of the openings in the front cover plate of the electronic keyboard when applied to the internal surface of that front cover plate about a periphery enclosing all of the openings. The membrane has punched in it a pattern of apertures corresponding in size, shape and position to the shaft shoulders on the keyboard switches, rendering the membrane capable of being seated about all of the shoulders, rather than interference fitted on the keyboard switch shafts, thereby allowing the to operate independently from the membrane.

The adhesive coating is applied to the surface of the pliable membrane facing away from the front cover plate, whereby the seating of the pliable membrane about all of the keyboard switch shaft shoulders results in the membrane becoming adhesively bonded to the keyboard switch shoulders and switch bodies.

The retainer consists of a stamped retaining frame made of a rigid material, such as steel, for holding the membrane in place against the internal surface of the front cover plate. The retaining frame is stamped in a shape and to the perimetric dimensions of a periphery on the front cover plate enclosing all of the openings, so that placing the retaining frame against the pliable membrane about its perimeter, and tightening the frame against the internal surface of the front cover plate by means of internal spacer supports, results in the pliable membrane being compressed between the retaining frame and the front cover plate, thereby forming a seal about the periphery on the internal surface of the front cover plate enclosing all of the openings.

Any contaminants, therefore, that pass through the front cover plate openings are stopped by the pliable membrane shield which is compressively sealed about its periphery and adhesively sealed around the membrane apertures for shaft extension therethrough, thereby prohibiting the passage of such contaminants into the internal keyboard electronics.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of the electronic keyboard showing the keyboard switch keytops, the front cover plate, the pliable membrane, the stamped retaining frame, the spacer supports, and the electronic circuit board with keyboard switches attached thereto.

FIG. 2 is a plan view of the keyboard with successive layers broken away to reveal the underlying structure.

FIG. 3 is an enlarged side sectional view taken along line 3--3 of FIG. 2.

DETAILED DESCRIPTION

In FIG. 1 there is shown in exploded perspective view, an electronic keyboard consisting of an electronic circuit board 10, a stamped retaining frame 12, a pliable membrane 14, and a front cover plate 16.

The electronic circuit board 10 has drilled in it holes 20 for the extension in an inward direction therethrough it of screws 22. Attached to the interior face 18 of the electronic circuit board 10 are keyboard switches 24 consisting of keyboard switch bodies 26, keyboard switch shoulders 28, keyboard switch shafts 30 and keyboard switch keytops 32, see also FIGS. 2 and 3. For clarity, all but one row of the keyboard switches 24 and the keyboard switch keytops 32 have been illustrated in dashed lines. Front cover plate 16 has stamped in it a number of openings 34 for extension therethrough of keyboard switch keytops 32, and has attached to its internal surface 35, about a periphery around all of the stamped openings 34 and at points between those stamped openings 34, a number of threaded studs 36, see also FIG. 3. The pliable membrane 14 has punched in it a number of round holes 38 for extension therethrough of studs 36, see also FIG. 2, and a number of square holes 40 for extension therethrough of the keyboard switch shoulders 28 and the keyboard switch shafts 30. The pliable membrane 14 also has formed pockets 42 corresponding to the grouping of the keyboard switches 24 to facilitate adhesive bonding of the pliable membrane 14 to the keyboard switch bodies 26. The stamped retaining frame 12 has punched in it a number of round holes 44 for extension therethrough of studs 36, see also FIG. 2, and has stamped in it a large opening 46 for encompassing all of the punched square holes 40 within the formed pockets 42 on the pliable membrane 14. Also shown in the exploded perspective view in FIG. 1 are hexagonal spacer supports 48 which are interposed between the stamped retaining frame 12 and the electronic circuit board 10 to provide support for the electronic keyboard and proper spacing between the front cover plate 16 and the electronic circuit board 10, see also FIG. 3. For clarity, only a few of the hexagonal spacer supports 48 are illustrated.

In FIG. 2 there is shown a plan view of the electronic keyboard showing successive layers broken away from right to left exposing the underlying structures. The far right area of FIG. 2 shows the top view of the front cover plate 16 with its stamped openings 34 and the keyboard switch keytops 32 extending therethrough. Breaking away the front cover plate 16 to expose the first underlying structure in FIG. 2 reveals the top view of pliable membrane 14 seated over the keyboard switch bodies 26 so that only the keyboard switch shoulders 28 and keyboard switch shafts 30 which extend through the punched square holes 40 of the pliable membrane 14 are exposed. Also seen on pliable membrane 14 are the punched round holes 38 for extension therethrough of studs 36. Breaking away the pliable membrane to expose the next underlying structure in FIG. 2 reveals the keyboard switch bodies 26, with keyboard switch shoulders 28 and keyboard switch shafts 30, connected to the electronic circuit board 10. Stamped retaining frame 12 is shown with punched round holes 44 for extension therethrough of studs 36. Finally, breaking away a corner of stamped retaining frame 12 to expose the last underlying structure of FIG. 2 reveals the electronic circuit board 10 with attached hexagonal spacer supports 48 attached to screws 22, see FIG. 3.

In FIG. 3 there is shown a side sectional view of a constructed electronic keyboard with attached seal. In the constructed keyboard, the pliable membrane 14 is located on the internal surface 35 of the front cover plate 16 with the round punched holes 38 in the pliable membrane 14 positioned on the threaded studs 36 on the internal surface 35 of the front cover plate 16. Stamped retaining frame 12 is then located against pliable membrane 14 with the round punched holes 44 in the stamped retaining frame 12 positioned also on the threaded studs 36 on the internal surface 35 of the front cover plate 16, thereby trapping the pliable membrane 14 between the stamped retaining frame 12 and the front cover plate 16. The hexagonal spacer supports 48 are then tightened onto the threaded studs 36 against the stamped retaining frame 12, thereby compressing the pliable membrane 14 between the stamped retaining frame 12 and the internal surface 35 of the front cover plate 16. An adhesive 49 is applied to the surface 50 of the pliable membrane 14 facing away from the front cover plate 16, and the front cover plate 16 with attached pliable membrane 14, stamped retaining frame 12 and hexagonal spacer supports 48, is set in place over the electronic circuit board 10 with attached keyboard switches 24 such that the keyboard switch shafts 30 extend through the punched square holes 40 in the pliable membrane 14 and out the openings 34 in the front cover plate 16. The adhesively coated surface 50 at the bottom of each of the formed pockets 42 in the pliable membrane 14 is then bonded to the tops of the keyboard switch bodies 26, with the punched square holes 40 in the pliable membrane 14 being seated and adhesively bonded around the keyboard switch shoulders 28. The constructed keyboard is completed by tightening screws 22 into the hexagonal spacer supports 48, and assembling the keyboard switch keytops 32 onto the keyboard switch shafts 30 extending through the stamped openings 34 in the front cover plate 16.

The sealing membrane 14 of this electronic keyboard arrangement is secured to the front cover plate and to the keyboard switch bodies about the keyboard switch shoulders, and is not secured in any way to the keyboard switch shafts, thereby allowing the keyboard switches to operate independently from the membrane, as is illustrated by the depressed key in FIG. 3.

Thus, the described embodiments of the present invention provide a keyboard arrangement sealed to prevent the introduction into the internal keyboard electronics of such contaminants as exist in the operating environment, wherein the seal is so constructed as to allow the keyboard switches to operate independently from the seal. While particular embodiments have been shown and described, it should be understood that many other arrangements using the teachings of this disclosure could be utilized without varying from the scope and spirit of the invention or the appended claims.

Claims

What is claimed is:

1. An improved electronic keyboard comprised in part of an electronic circuit board with keyboard switches connected thereto having keyboard switch bodies, keyboard switch shafts, keyboard switch shoulders and keyboard keytops; and a front cover plate attached to the board by means of spacer supports, and having openings for extension therethrough of the keyboard switch keytops; wherein the improvement comprises:

a. a shield, having a size and shape capable of encompassing all of the openings in the front cover plate, and being secured to an internal surface of the front cover plate enclosing all of the openings in the front cover plate, said shield having apertures corresponding in size, shape, and position to the keyboard switch shoulders for receiving the shoulders;

b. an adhesive coating on a surface of said shield facing away from said front cover plate for bonding said shield to the keyboard switch bodies about the keyboard switch shoulders to prevent the introduction onto the electronic circuit board of such contaminants as may pass through the front cover plate openings, while permitting the keyboard switches to operate independently from the shield; and

c. a retainer, having for its shape and perimeter the shape and perimeter of said shield, and cooperating with the spacer supports for clamping said shield between said retainer and the front cover plate, thereby securing said shield to the internal surface of the front cover plate about the periphery of said shield and enclosing all of the openings in the front cover plate.

2. The apparatus of claim 1, wherein said shield further comprises an impervious pliable membrane, having a size and shape capable of encompassing all of the openings in the front cover plate, and having apertures corresponding in size, shape, and position to the keyboard switch shoulders.

3. The apparatus of claim 2, wherein said retainer further comprises a stamped retaining frame, having for its shape and perimeter the shape and perimeter of said shield.

4. An improved electronic keyboard comprised in part of an electronic circuit board with keyboard switches connected thereto having keyboard switch bodies, keyboard switch shafts, keyboard switch shoulders and keyboard switch keytops; and a front cover plate attached to the board by means of spacer supports, and having openings for extension therethrough of the keyboard switch keytops; wherein the improvement comprises:

a. an impervious pliable membrane, having a size and shape capable of encompassing all of the openings in the front cover plate, and being secured to an internal surface of the front cover plate enclosing all of the openings in the front cover plate, said membrane having apertures corresponding in size, shape, and position to the keyboard switch shoulders for receiving the shoulders;

b. an adhesive coating on a surface of said membrane facing away from said front cover plate for bonding said membrane to the keyboard switch bodies about the keyboard switch shoulders to prevent the introduction onto the electronic circuit board of such contaminants as may pass through the front cover plate openings, while permitting the keyboard switches to operate independently from the membrane; and

c. a stamped retaining frame, having for its shape and perimeter the shape and perimeter of said membrane, and cooperating with the spacer supports for clamping said membrane between said frame and the front cover plate, thereby securing said membrane to the internal surface of the front cover plate about the periphery of said membrane and enclosing all of the openings in the front cover plate.