THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
NATURE OF THE INVENTION

SELF-LOCIKING IN RUBBER KEY PAD
numbered as dated
A) FIELD OF TECHNOLOGY:
1. This invention relates to elastic material design and specifically to rubber key and more particularly to effective and optimal way of designing a self locking key for key boards used in medical equipments more so like Ultrasound scanning machines.
2. The present invention relates to the structure of a soft key having a particular application in the field of manufacture of keypads for medical equipments. Market forces require that medical device manufacturers produce an ever-increasing variety of keypads with versatile and easy to use designs. The present invention is a novel step in the direction, which carries an industrial usage and commercially viable in the field of manufacturing of keypads for medical equipments.
B) DESCRIPTION OF PRIOR ART:
3. Hardware keyboards are designed to communicate with the electronic device acting
as a user interface. It is customary to get soft touch to the keyboard for user ease.
It is mandatory that the soft keys installed be firmly struck to the keyboard.
Needed, then, is a soft material dropped on to the hardware, which can firmly
attach itself to the keyboard. In a given situation, use of adhesives or glue to lay
down the soft material on to the hardware is undesirable if there is a means to
avoid using them. Needed, then, is a soft material that can automatically lock itself
to the hardware or the keyboard.

4. A conventional structure of the keypad comprises of a membrane circuit, a flat frame mounted on the membrane circuit to hold a set of key switches in respective openings. As stated above needed then is a soft material that can automatically lock itself to the hardware or the keyboard. In general the function of a key in a keyboard can be summarized as follows;
5. The depression of the key causes the projection to urge the contact the next layer where it activates printed wire assembly (PWA). Upon releasing the pressure to the key, the key should return to natural-bias position in which the electrical terminals are not electrically connected. Upon depression of the key it causes a second distorted position in which the electrical terminals are connected.
6. Common way of having a spring structure for the up and down motion of the key is undesirable as the functionality of the key then becomes dependent on at least two components namely; the key and then the appropriate positioning of the key with respect to the base PWA on which it is attached. Failure of any one of components can make the whole key nonfunctional. Needed then is a soft material key which can lock itself to the keyboard and establish the up and down movement without help of any other agency such as a separate fastener.
C) OBJECT OF THE INVENTION:
7. It is the primary object of the invention to invent a rubber key which has a self locking property.
8. It is another object of the invention to invent a soft keypad, which can operate (move up and down) on the PWA without help of any external material such as a fastener.

9. It is another object of the invention is to invent a tapering portion that can easily be depressed into the hole of a PWA.
10. It is another object of the invention to invent a sufficiently long tapering portion which can be pulled from the other side of the key board.
11. It is another object of the invention to invent a keypad without any additional adhesive to fix to a keyboard.
12. It is another object of the invention to invent a keypad that can be easily assembled to the PWA without the use of any additional tools
D) PROPOSED SOLUTION:
13. To accommodate the needs mentioned above and to circumvent the problems mentioned above we have designed a rubber keypad with a self locking property.
14. The key designed to have fastening mechanism in rubber keypad where in it has to activate the keys in printed wire assembly (PWA's) the pip will enforce the key pad rigidly into the PWA and making it firm in its position. The length of the pip is kept sufficiently long to hold and pull from the other side of the key hole. Due to the pull the change in length of the rubber key forces to change the circular dimension the pip. The pip is given the entry chamber to make it possible to enter in the hole given in PWA. The stress on pulling the pip makes the diameter of the pip slender. This helps the pip to easily pass through the hole on the PWA, which is smaller in size than the diameter of the pip in its normal position. The expansion of the pip after pulling is done makes to hold the PWA and fasten rigidly to the PWA. This eliminates the natural way of fixing by using temporary fasteners in PWAs

The presented method provides flexibility of manufacturing the key with less accuracy to get into the hole of key board. This also reduces the rejection and very high precession tooling processes.
E) BEST METHOD OF PERFORMANCE OF INVENTION WITH BRIEF DESCRIPTION OF DIAGRAM
15. To summarize, the scheme presented here is implemented by designing key pad as given in the figure in an Ultrasound scanner. The key consists of flat side, marked as 1 in Figure A, which resides at the surface of the flexible keypad for human interaction. The flat side consists of a rod shaped, marked as 2 in Figure A portion with a tapering end, which is pushed into key board or PWA, marked as 3 in Figure B through a key hole provided for to facilitate the purpose, marked as 4 in Figure B. Once pushed into the key hole the tapering portion of the key is pulled from the other side of the PWA as shown in Fig D and so the diameter of the key reduces and when released gets an auto lock because the diameter again increases back marked as 5 in Figure E.
F) SCOPE OF THE INVENTION:
16. The invention may be used in manufacturing keypads, more particularly keypads used in Medical Equipments like Ultrasound devices or any other like medical device components. The advantage(s) of this invention is to provide a simple but effective solution and invent a rubber key which has a self locking property. As the primary object of the invention being to invent a soft key which can operate (move up and down) in PWA without help of any external material such as a spring and that can easily be depressed into the keyhole of a PWA and to invent a key without any additional adhesive to fix to a keyboard the invention is novel and carries wide

public utility in the field of manufacturing of keyboards used more particularly in medical devices.
17. Although the invention has been described with reference to specific embodiments, this invention is not to be construed in limiting sense. Various modification(s) of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined.

G) WE CLAIM:
The flexible and stretchable key with self-locking capability is claimed. We claim:
1. A keypad comprising.
i) A depressible keypad which can self lock to the keyboard or PWA;
ii) A one-piece keypad element comprising a pip or multiples of it
iii) A key wherein a feature to pull the pip reducing its diameter makes it insertable into the key hole and upon release locks itself to the key board.
2. A key which sticks to the key board without any adhesive of additional fasteners
3. A key assembly as in claim 1, wherein the region of the tapering portion long enough to pull from the other side of the keyboard.
4. A key material as in claim 1, wherein the diameter of the rod portion reduces upon
pulling and again retain back it diameter upon release.
5. A key, which automatically locks to the key board without any adhesive or any external support.
6. An assembly comprising:
i) a plurality of keys mounted, for depression, to a substrate; and wherein
each key includes a face which the user can depress and a depending annular wall, defining a cavity, arranged to confront a contacting electrical circuit.


To,
The Controller of Patents, The Patent office, At Chennai.