Reduced noise key unit

Information

  • Patent Grant
  • 6672781
  • Patent Number
    6,672,781
  • Date Filed
    Thursday, April 27, 2000
    24 years ago
  • Date Issued
    Tuesday, January 6, 2004
    20 years ago
Abstract
A key unit of a keyboard apparatus having at least one bumper extending from the key unit for cushioning the impact of the key unit against the enclosure of the keyboard apparatus when the key unit assumes a depressed position and/or when the key unit resumes a non-depressed position, thereby eliminating or reducing the feedback noise, while retaining the benefits of a pre-loaded feature for the key unit.
Description




FIELD OF INVENTION




The present invention relates generally to a keyboard apparatus used for electronic equipment such as personal computers, typewriters, calculators, word processors and the like, and, more particularly, to a key unit in a keyboard apparatus, as well as the keyboard apparatus itself, wherein the key unit is adapted to reduce the noise which is typically generated when a key unit is pushed or returns from the depressed position and hits the top plate of a keyboard or other type of shell around the key unit.




BACKGROUND OF THE INVENTION




Keyboards are known as signal input devices that allow transmission of a relevant signal to a host device in response to the mechanical pressure being applied to a certain key unit out of a plurality of key units disposed in a predetermined positional relationship on a board in an electronic device or equipment. While keyboards are used in a variety of different electronic devices, the keyboards utilized in these devices usually perform the same function. Namely, an individual key unit of a plurality of key units of a keyboard usually consists of a key button that can be depressed by application of the mechanical pressure to the top of the key button, urging the key unit into movable contact with a contact point on a conductive membrane formed on a circuit substrate of the keyboard, which produces an electrical connection and causes a signal to be sent to the host device. Examples of various keyboard devices and their operation are well known in the art and disclosed in U.S. Pat. Nos. 4,677,600, 5,516,996 and 5,565,865.




Generally, there are many types of different key units that can be utilized in a keyboard. For example, U.S. Pat. No. 5,456,541 describes resilient rubber, spring and mechanical types of key units. Similarly, a resilient rubber key unit is described in U.S. Pat. No. 5,565,865.




In a conventional key unit, the key unit has a resilient pad, usually made of a resilient rubber or silicon rubber material, and a plastic keycap that is mounted on top of the resilient pad. The plastic keycap extends in the axial direction through the pre-determined opening in the top plate of the keyboard to accommodate the axial movement of the pad and keycap in response to the mechanical pressure in the axial direction that is applied by the keyboard operator to the top surface of the plastic keycap. The resilient pad is mounted over a conductive membrane sheet structure.




Electrical conductivity is provided in a conventional conductive membrane sheet structure below the resilient pad which is formed by stacking a lower sheet and an upper sheet, on which conduction layers are formed respectively. The bottom surface of the resilient pad has a stem portion that moves in unison with the pad in the axial direction and affects the contact between the fixed contact on the lower sheet of the conductive membrane sheet structure formed on a circuit substrate and the movable contact of the upper sheet. The upper and lower sheets of the conductive membrane sheet structure are separated from each other by a predetermined gap or an air pocket formed by the spacer inserted therebetween. When the stem portion of the resilient pad urges the movable contact of the upper sheet into physical contact with the fixed contact of the lower sheet an electrical circuit is established. Alternatively, electric conductivity is provided by a semi membrane or a PCB type of conductive membrane, which comprise a single conductive layer formed on a membrane sheet or circuit substrate. When the stem portion of the resilient pad is urged in the axial direction a conductive portion of the stem portion completes an electric circuit between a fixed row contact point and a fixed column contact point.




In addition, a conventional key unit may have a “pre-loaded” feature which is accomplished by using a flange on the keycap to limit the axial movement of the key unit. The flange contacts a pair of plastic ribs which are fixedly suspended from the inner surface of a top plate of the keyboard apparatus. These plastic ribs act as a stop and limit the axial movement of the key unit when it returns from a depressed position to its normal position.




The pre-loading is typically used to add stability and insure a constant height of the keycap. However, because the keycap is pre-loaded, each time a user depresses and thereafter releases the key unit, the flange of the keycap, strikes against the plastic ribs creating an undesirable impact and noise, often referred to as “feedback noise.” Therefore, there is a need for an improved keyboard apparatus, in which the key units of the keyboard apparatus have the “pre-loaded” feature and associated advantages, but do not produce the impact and noise associated with the operation of conventional key units. Reduction of the impact and noise associated with the operation of keyboards in personal computers is particularly desirable because these devices are often used in enclosed public places, such as schoolrooms, on airplanes, and in large open office spaces that are subdivided into individual work areas, where the noise can be distracting and degrade productivity.




SUMMARY OF THE INVENTION




It is an object of the current invention to provide a keyboard apparatus that either eliminates or reduces the “feedback noise” during its operation.




Another object of the current invention is to provide an improved key unit which may be one of a variety of different types that has “pre-loaded” functionality and eliminates the above-mentioned feedback noise and impact, thereby providing a cost-effective solution to keyboard manufacturers, without limiting them to only one type of key unit.




A further object of the present invention is to provide an improved key unit for various types of electronic devices that utilize a keyboard with one or a plurality of key units, where the improved key unit contains means for cushioning the impact of a key unit against the top enclosure of a keyboard, thereby eliminating the feedback noise, and at the same time retaining the benefits of a “pre-loaded” feature for a key unit.




These and other objects of the invention are accomplished by providing a key unit having at least one resilient bumper positioned on or extending from the key unit which cushions the impact of the key unit against the top plate of the keyboard when the key unit returns from a depressed position to a normal pre-loaded position. The resilient bumper may be incorporated in a variety of different types of key units such as a resilient rubber type, spring type, mechanical type or any other type of key unit that may or may not contain a plastic keycap that covers the movable portions or key pad of the key unit.




These and other objects of the invention are accomplished by providing a key unit that is able to assume a depressed position comprising in one embodiment a member movable in a defined direction in response to pressure, the member having at least one resilient bumper. The key unit is a component of an apparatus that has a stop that restricts the movement of the key unit when the key unit is returned from the depressed position. In addition, the bumper of the key unit is movable into contact with the stop of the apparatus when the key unit is pushed or returned from the depressed position.




These and other objects of the invention are accomplished by providing an apparatus comprising at least one such key unit.











BRIEF DESCRIPTION OF THE DRAWINGS




These and other objects, features and advantages of the invention, its construction and operation will be best understood from the following detailed description of preferred embodiments of the present invention, taken in conjunction with the accompanying drawings, of which:





FIG. 1

is a disassembled view of a key unit according to the present invention;





FIG. 2

is a disassembled view of a first type of a key unit according to the present invention;





FIG. 3A

is a disassembled view of a second type of a key unit according to the present invention;





FIG. 3B

is a disassembled view of a third type of a key unit according to the present invention;





FIG. 4

is a disassembled view of a fourth type of key unit according to the invention;





FIG. 5

is a disassembled view of a fifth type of a key unit according to the present invention; and





FIG. 6

is a sectional view of a key unit according to the present invention similar to that shown in FIG.


5


.











DETAILED DESCRIPTION OF THE INVENTION




The key unit according to the present invention will now be discussed with reference to the drawings in

FIGS. 1 through 6

in which like reference numerals denote corresponding parts.

FIG. 1

illustrates a key unit


61


according to the present invention comprising a member


60


having bumpers


62




a


and


62




b


. In operation, the member


60


is moveable in the directions shown by the arrow A. Member


60


is included in an apparatus having a stop


64


which impacts bumpers


62




a


and


62




b


when member


60


moves upwards in the direction shown by arrow A. Member


60


assumes a depressed position in response to a condition, such as pressure exerted by a keyboard operator on the key unit


61


, and in the absence of the condition, resumes a normal position. Member


60


is either a single restorative component, as shown, or includes at least one restorative component, which is capable of responding to the absence of a condition, such as pressure, by restoring attached or physically proximate components to their normal position. The restoration component of member


60


is resilient or otherwise acts against the condition (i.e., the pressure exerted by the keyboard operator). In the absence of the condition, member


60


resumes a non-depressed position, which restores other components of the key unit which are attached to member


60


or physically proximate to member


60


to their normal position. Member


60


may produce a counter force in response to pressure and may store energy which, in the absence of pressure, restores attached or physically proximate components to their normal position.




In the case of member


60


being a single restorative component, exemplary embodiments of member


60


include but are not limited to a pad made of resilient material, such as silicon rubber, or any other type of rubber, a spring, a coil, an elastic band, a mechanical device operating using for example, hydraulics or magnetic forces or any other component capable of assuming a depressed position in response to a condition and in the absence of the condition, resuming a non-depressed position. If member


60


comprises a single component, bumpers


62




a


and


62




b


are attached to member


60


, or alternatively, bumpers


62




a


and


62




b


and member


60


are made as a one-piece unit.




In the case of member


60


being more than one component comprising at least one restorative component, member


60


may be a combination of hard plastic key cap or key top or any other component or combination of components used with at least one restorative component such as a pad made of resilient material, such as silicon rubber, or any other type of rubber, a spring, a coil, an elastic band, a mechanical device operating using for example, hydraulics or magnetic forces or any other component capable of assuming a depressed position in response to a condition and in the absence of the condition resuming a non-depressed position. If member


60


comprises more than one component, bumpers


62




a


and


62




b


may be attached to or manufactured as a one-piece unit with any component of member


60


which allows bumpers


62




a


and


62




b


to extend from member


60


and impact stop


64


. Bumpers


62




a


and


62




b


may be attached to or manufactured as a one-piece unit with a restorative component of member


60


as long as bumpers


62




a


and


62




b


do not excessively impede the restoration capabilities of the restorative component.




As can be seen from

FIG. 1

, bumpers


62




a


and


62




b


extend from member


60


and cushion the impact of member


60


when member


60


returns to a normal position which reduces or eliminates feedback noise. Bumpers


62




a


and


62




b


are made of resilient or cushioning material, such as silicon rubber or any other rubber or resilient material, Styrofoam, or foam. Bumpers


62




a


and


62




b


may be ribs, ridges or extensions of member


60


. As shown, bumpers


62




a


and


62




b


cushion impact between member


60


and the stop


64


of the apparatus when member


60


resumes a normal, non-depressed position. Alternatively, or in addition, bumpers


62




a


and


62




b


may cushion impact between member


60


and the stop


64


of the apparatus when member


60


assumes a depressed position. Bumpers


62




a


and


62




b


may be used for a pre-loaded key unit.





FIG. 2

illustrates a first embodiment of the present invention, key unit


102


. The key unit


102


which is able to assume a depressed position comprises a member where the member is a resilient pad


70


movable in a defined direction (up and down in the axial direction) in response to pressure. The pressure is exerted by a keyboard operator pushing the top surface


75


of resilient pad


70


. The resilient pad


70


has resilient bumpers


125




a


and


125




b


. The bumpers


125




a


and


125




b


are protrusions from the sides of the resilient pad


70


. The resilient pad


70


with bumpers


125




a


and


125




b


are movable in the axial direction into contact with stop


170


when the key unit


102


is returned from the depressed position. The stop


170


is the top plate of the keyboard having inner surface


172


and pre-determined opening


160


. The resilient pad


70


extends in the axial direction through the pre-determined opening


160


in the top plate


170


. The resilient pad


70


is preferably made of a rubber material, such as, for example, silicon rubber. A key cover


90


may be attached (directly or indirectly) to the top surface


75


of the resilient pad


70


. In that case, the keyboard operator pushes the key cover


90


to depress the key. Key cover


90


is made of plastic, or any other material which is resistant to wear due to pushing, and indicia of the key unit, such as an alphanumeric symbol or other indicia may be printed or engraved on the key cover


90


.





FIG. 3A

illustrates a second embodiment of the present invention, key unit


104


. Key unit


104


comprises a member, where the member includes a base


94


which is movable in a defined direction (up and down in the axial direction) in response to pressure exerted by a keyboard operator pushing key cover


90


thereby allowing key unit


104


to assume a depressed position. Key cover


90


may be fixed to or rest directly on the top surface (not shown) of base


94


or key cover


90


and base


94


may be manufactured as a single piece. Base


94


has bumpers


96




a


and


96




b


. Bumpers


96




a


and


96




b


protrude from the sides of base


94


and are movable in the axial direction into contact with stop


170


when the key unit


104


is returned from the depressed position. The member of key unit


104


also includes a restorative device


93


which is attached to the bottom surface of the base


94


when key unit


104


is assembled. When pressure is exerted by the keyboard operator, conductive layer


190


moves downward to cause contact which forms an electrical circuit and produces a signal to the keyboard apparatus. The restorative device acts against the pressure by the operator. When the keyboard operator ceases to apply pressure, the natural elasticity of conductive layer


190


breaks the electrical connection so that no further signal is produced to the keyboard. Restorative device


93


responds by restoring base


94


and bumpers


96




a


and


96




b


to their normal position.




The base


94


may extend in the axial direction through the predetermined opening


160


in the top plate


170


or alternatively, only the restorative device


93


may extend through the predetermined opening


160


. The base


94


need not be made of a resilient material but may be made of plastic, or any other non-resilient material.




In an alternative embodiment, as shown in

FIG. 3B

, the member is made of base


94


and restorative device


93


. The restorative device


93


of key unit


106


is a resilient spring


92


which is connected to the bottom surface of base


94


.





FIG. 4

illustrates a fourth embodiment of the present invention in which the key unit comprises resilient pad


120


having a thick lower portion


122


and a thin upper portion


123


. In this embodiment, the stop is provided by a pair of ribs


175




a


and


175




b


on the inner surface


172


of top plate


170


. The thinner portion


123


of resilient pad


120


extends in the axial direction through the pre-determined opening


160


in the top plate


170


. Since this embodiment does not include key cover


90


, the keyboard operator applies pressure directly to the top of thinner portion


123


thereby producing movement of the pad in the axial direction. In this embodiment, the indicia of the key unit, such as an alphanumeric symbol or other indicia is printed on the top surface


174


of top plate


170


.





FIG. 5

illustrates a fifth embodiment of the present invention. As shown in

FIG. 4

, key unit


110


has a plastic keycap


130


that is mounted on top of the resilient pad


120


. The plastic keycap


130


extends in the axial direction through the pre-determined opening


160


in the top plate


170


of the keyboard to accommodate the axial movement of the resilient pad


120


and keycap


130


in response to the mechanical pressure in the axial direction that is applied by the keyboard operator to the top surface


135


of the plastic keycap


130


.




Referring to

FIGS. 4 and 5

, impact and feedback noise are reduced or eliminated by a pair of resilient bumpers


125




a


and


125




b


, preferably made of a rubber material such as silicon rubber material, that come into contact with the stop of the top plate


170


. These resilient bumpers may be ribs, ridges or extensions of the resilient pad


120


extending in the axial direction, as shown in

FIGS. 3 and 4

. The stop is preferably a pair of ribs


175




a


and


175




b


fixedly suspended from the inner surface


172


of the top plate


170


of the keyboard as shown in

FIGS. 3 and 4

. Alternatively, the stop may be provided by the top plate


170


of the keyboard itself as shown in

FIG. 2A

, or any other known means that would physically restrict the axial movement of the key unit by contact with the resilient bumpers


125




a


and


125




b


when the key unit returns from a depressed position to a normal position.




In the embodiment shown in

FIG. 5

, the plastic keycap


130


has a flange


132


that accommodates the resilient bumpers


125




a


and


125




b


through a pair of corresponding apertures


134




a


and


134




b


in the flange. This allows the resilient bumpers to come into physical contact with the stop provided by the pair of corresponding ribs


175




a


and


175




b


, instead of delimiting the axial movement of a key unit through the contact of the flange


132


and the stop, as in conventional key units known in the prior art. The flange


132


rests upon shoulder


133


of the resilient pad


120


.




Referring to

FIG. 5

, the plastic keycap


130


preferably comprises a thicker button base as the upper part of the keycap. The upper surface


135


of the button base preferably contains the indicia of the key unit such as an alphanumeric symbol or other indicia.




As shown in

FIG. 6

, in the preferred embodiments of the current invention, the resilient pad


120


is mounted over a conductive membrane sheet structure


190


that is formed by two conductive layers and a gap in-between these layers. The conductive membrane sheet structure


190


produces an electrical signal in response to the mechanical pressure applied to the key unit. The conductive connection that produces the electrical signal of the key unit according to the present invention is accomplished in the same way as the conductive connection of a conventional key unit. The bottom surface


125


of the resilient pad


120


has a stem portion


128


that moves in unison with the pad


120


in the axial direction into contact with a surface contact point on upper sheet


192


of the conductive membrane sheet structure


190


, thereby affecting the contact between the fixed contact


195


formed on the lower sheet


194


of the conductive membrane sheet structure


190


which may be formed on a circuit substrate (not shown) and the movable contact


193


of the upper sheet


192


. The upper and lower sheets are separated from each other by a predetermined gap or air pocket


191


. Alternatively a semi membrane, a PCB type of conductive membrane may be used as the means for producing an electrical signal in response to mechanical pressure enabled in the key unit. Such structure forms the electric contact and produces the signal to the keyboard apparatus in response to the contact between the stem portion


128


of the resilient pad


120


and a pre-determined contact point on the conductive membrane which may be formed on a circuit substrate.

FIG. 5

further shows the key cap


130


having a button base in the upper part of the key cap. The upper surface of the button base


135


may contain indicia of the key unit. The bottom base may be a thicker part of the key cap


120


.




Although the invention has been described with reference to the preferred embodiments, it will be apparent to one skilled in the art that variations and modifications are contemplated within the spirit and scope of the invention. The means for producing an electrical signal in response to mechanical pressure or movement may be any type of structure known such as a capacitive structure where the pressure changes the capacitance of circuit elements, a thermosensitive, inductive, photosensitive or piezoelectric structure. The drawings and description of the preferred embodiment are made by way of example rather than to limit the scope of the invention, and it is intended to cover withing the spirit and scope of the invention all such changes and modifications.



Claims
  • 1. A key unit of an apparatus, wherein said key unit is able to assume a depressed position, and wherein said apparatus has a stop that restricts the movement of said key unit, said key unit further comprising:a member moveable in a defined direction in response to pressure, said member having at least one bumper, said bumper moveable into contact with said stop of said apparatus, and a keycap mounted on said member, wherein said keycap comprises a flange that accommodates said at least one bumper of said member through at least one aperture in said flange into said contact with said stop of said apparatus.
  • 2. A key unit as claimed in claim 1, wherein said apparatus has an electrical signal producing means for producing an electrical signal in response to said pressure, and wherein said member is mounted in a position above said electrical signal producing means, said member having a bottom surface being movable in said defined direction by said pressure to engage said electrical signal producing means.
  • 3. A key unit as claimed in claim 1, wherein said member is a pad.
  • 4. A key unit as claimed in claim 3, wherein said pad is made of a resilient material.
  • 5. A key unit as claimed in claim 1, wherein said member and said at least one bumper of said member are made of a silicon rubber material.
  • 6. A key unit as claimed in claim 1, wherein said apparatus has a top plate having an inner surface, and wherein said stop of said apparatus comprises at least one rib fixedly suspended from said inner surface of said top plate of said apparatus in said defined direction and restricting said movement of said key unit upon said contact with said at least one bumper of said member.
  • 7. A key unit as claimed in claim 1, wherein said at least one bumper of said member extends along-side said keycap into contact with said stop of said apparatus.
  • 8. A key unit as claimed in claim 1, wherein said keycap further comprises a button base in the upper part of said keycap, said base containing the indicia of said key unit.
  • 9. An apparatus comprising:at least one key unit being able to assume a depressed position; and a stop that restricts the movement of said at least one key unit; wherein said at least one key unit comprises: a member moveable in a defined direction in response to pressure, said member having at least one bumper, said bumper moveable into contact with said stop of said apparatus, and wherein said key unit of said apparatus further comprises a keycap mounted on said member, and wherein said keycap of said key unit further comprises a flange that accommodates said at least one bumper through at least one aperture in said flange into said contact with said stop of said apparatus.
  • 10. An apparatus claimed in claim 9, wherein said member of said key unit is mounted in a position above an electrical signal producing means for producing an electrical signal in response to said pressure applied to said at least one said key unit; said member having a bottom surface being movable by said pressure in said defined direction to engage said electrical signal producing means.
  • 11. An apparatus claimed in claim 9, wherein said member of said key unit is made of a resilient material.
  • 12. An apparatus claimed in claim 9, wherein said member of said key unit and said at least one bumper of said member are made of a silicon rubber material.
  • 13. An apparatus claimed in claim 9, wherein said keycap mounted on said member for movement in unison with said member, wherein said at least one bumper of said member extends along-side said keycap into said contact with said stop of said apparatus when said key unit is returned from said depressed position.
  • 14. An apparatus claimed in claim 9, wherein said keycap of said key unit further comprises a thicker button base in the upper part of said keycap, said base containing the indicia of said key unit.
  • 15. An apparatus as claimed in claim 9, wherein said member comprises a restorative component.
  • 16. An apparatus as claimed in claim 15, wherein said restorative component is a spring.
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