The present invention relates to an apparatus for a hinge key switch, and more particularly to a construction of a key switch having a rubber spring which provides vertical resistance against a key cap, movement of which operates around a hinge point, and a stopper which acts to limit that movement.
Information is input into electronic devices, such as computers and other types of data terminals, by means of a keyboard. Accordingly, the construction of the key switches of the keyboard becomes important in that the key switches must be durable and be able to be manually depressed in a consistent and easy manner. Two alternative methods of construction of these key switches have heretofore been contemplated. These two types of switches are commonly known as the “plunger-type” key switch and the “scissors-type” key switch.
Referring first to
The keyboard mounting plate 101 itself is affixed to a back plate 102. Disposed between the back plate 102 and the keyboard mounting plate 101 is a signal membrane 103. Further disposed between the keyboard mounting plate 101 and the back plate 102, a resistance mechanism is provided to bias the plunger 115 in a vertically upward direction within the confines of the chamber. This resistance mechanism can sometimes be a rubber spring 107, as shown in the figure. The rubber spring 107 acts to bias the plunger 115 in the vertically upwards direction. Overtime, however, movement of the plunger 115 is often inhibited by dust, dirt or other debris which work their way into the narrow space between the vertical sliding mechanism 116 and the vertically extended portion of the keyboard mounting plate 101. Also, because there are many interacting and moving parts, the plunger-type key switch is subject to breakage.
Referring now to
Accordingly, when key cap 205 is manually depressed in a vertically downward direction the two arms of scissor mechanism 217 rotate about pivot point 208 such that the lower portions of the two arms slide horizontally in opposite directions in the slot formed in the mounting plate 201. A rubber spring 207, formed about the scissor mechanism 217, connected to the back plate 201 and to the underside of the key cap 205, provides resistance in the vertically upward direction. When the manual depression of the key cap in the vertically downward direction ends the key cap is biased by the rubber spring 207 in a vertically upwards direction. However, it is possible that dirt, dust and other debris will lodge in the slot of the mounting plate 201, in which the lower portions of each of the arms of the scissor mechanism 217 are connected, or between the arms themselves such as to prevent proper sliding and/or movement. Also, because there are many interacting and moving parts, the scissors-type key switch is subject to breakage.
Thus, as an be seen, there remains a need for a key switch which will provide the same sort of vertical movement of the key cap when manually depressed, but will not be subject to interference by dirt, dust or other debris becoming lodged in the moving parts and which will be less subject to wear, tear and breakage.
Accordingly, the present invention is directed to a hinged key switch having a construction in which a key cap rotates about a hinge point away from the vertical axis of a resistance biasing mechanism.
In a preferred embodiment, the key cap is constructed as a single unitary form. That is, the key cap has a slightly depressed top surface, for easy gripping by a fingertip, and a ledge and finger(s) integrally connected to and extending therefrom towards the hinge point. At the end of the fingers, away from the top surface of the key cap, the fingers angle down into slots cut into a keyboard mounting plate. At a point below the surface of the keyboard mounting plate, the fingers angle back towards the main body of the key cap so as create a snap hook for securing the key cap to the keyboard mounting plate. The key cap's surface can further also have edges which angle down.
Further in the preferred embodiment, the resistance biasing mechanism comprises a circular extension, integrally connected to and extending from an underside of the key cap, and a raised circular portion of a rubber spring, integrally connected to and extending from a rubber sheet. The circular extension of the key cap and the raised circular portion of the rubber spring are formed so as to fit onto and contact one another and mutually cooperate. The rubber sheet is disposed between the keyboard mounting plate and the back plate. The rubber spring itself fits into a hollow formed in the keyboard mounting plate and operates for biasing in a vertically upwards direction against manual depression.
The present invention, including its features and advantages, will become more apparent from the following detailed description with reference to the accompanying drawings.
Referring now to
Referring now to
Disposed between keyboard mounting plate 1 and back plate 2 is a signal membrane 3. Signal membrane 3 is well known in the art and usually consists of three individual sub-layers. The signal membrane acts to carry electrical signals from the keyboard to the electronic device. The three layers consist of a top and bottom layer of which one or both act as a circuit board having conductive pathways which carry the electrical signals, while the middle layer acts as a buffer between the top and bottom layer by means of its non-conductivity.
Also disposed between keyboard mounting plate 1 and back plate 2 is a rubber-sheet 4. Rubber sheet 4 resides on top of signal membrane 3 and is supported by both signal membrane 3 and the back plate 2.
Integrally formed on rubber sheet 4 is a resistance biasing mechanism 20 which extends upwards through slot 24 in keyboard mounting plate 1. In a preferred embodiment of the present invention, the resistance biasing mechanism 20 comprises a rubber spring 7. The rubber spring 7 is constructed of a flexible material and in the shape of a dome which has a hollow interior. The dome shape extends in an upward direction towards the key cap 5. The hollow interior of the dome allows the rubber spring 7 to be flexible, while the shape of the dome causes the rubber spring 7 to be biased towards the key cap 5. The construction of the rubber dome shape is well-known in the art, and accordingly is such that the dome is of such material and strength to create what is know as a “break-point”. That is, when pressure is applied against the dome shape, the dome temporarily collapses under the pressure allowing the key to be depressed. When the pressure is removed, the dome of the rubber spring snaps back into its original form. This movement returns the key cap to its original position. At a top portion of the dome shape a circularly-shaped extension 21 extends vertically upwards (i.e., towards the key cap 5). This circularly-shaped extension 21 from the dome has a slight angle at the horizontal plane, as shown in the figures, such that the side away from pivot point 8 is higher and has a longer length than the opposite side which is closer to the pivot point 8.
Key cap 5 is formed so that a top surface of the key cap is easily manipulated by the fingers of a hand. At one end of key cap 5 an extension 13 is provided in a generally horizontal direction buttressed at its far end by a ledge 14. At both diagonal ends of this ledge 14, there is located a finger 15 which extends a little way as shown in the figures. A second part of the finger(s) 15 then extends in a vertically downward direction at approximately a 90 degree angle from the generally horizontal plain of the extension 14. The further extension of the finger 15 fits through a slot 16 in the keyboard mounting plate, and ends in a snap hook 9. Snap hook 9 cooperates with an underside of keyboard mounting plate 1 so as to prevent key cap 5 from disengaging from its position. It is to be understood, of course, that as many or as few finger extensions and snap hooks may be used to secure key cap 5 to keyboard mounting plate 1. Such construction allows for each key switch to have as few as one pivot point 8, and to place such towards a top of the keyboard. However, it is to be further understood that the construction of the key cap can be such that the pivot point can be placed towards the bottom of the key board or even towards either of the sides.
The key cap 5, extension 13, ledge 14 and finger 15 are generally rigid but permit enough give so that the key cap can move in the vertical direction. A circular extension 6 extends from an underside of key cap 5. Circular extension 6 cooperates with a top portion of the circular extension 7. As can be seen in the figure, circular extension 7 has a slight angle at the horizontal plane which helps enable it to securely maintain contact with circular extension 6. The horizontal angle also allows for equal pressure to be applied across the dome of the rubber spring so as to allow for an even feel when manually depressed and to avoid unnecessary wear on one portion of the dome thereof.
Referring now to
Referring now to
Accordingly, the construction of the key switch of the present invention allows for a unique design in which the key cap is a single unitary structure and in which there is only one moving part. Such construction allows for a less complex key switch which nevertheless retains a sleek low profile. Thus, the key switch of the present invention is easier and cheaper to manufacture, and has both simplicity and profile which are superior to any predecessors.
In the foregoing description, the apparatus and method of the present invention have been described with reference to specific examples. It is to be understood and expected that variations in the principles of the apparatus and method herein disclosed may be made by one skilled in the art and it is intended that such modifications, changes, and substitutions are to be included within the scope of the present invention as set forth in the appended claims. The specification and drawings are accordingly to be regarded in an illustrative rather than in a restrictive sense.
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Number | Date | Country | |
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20040195082 A1 | Oct 2004 | US |