Key switch structure

A key switch assembly for use in a keyboard employing pressure sensitive electric switches disposed within a keyboard housing is provided. The key switch assembly includes a key switch socket member integrally formed on an upper panel of the keyboard housing to project axially upward therefrom. The key switch socket member includes an inner wall portion defining a receiving bore which has formed thereon an axially extended guiding slot spaced from a pair of appropriately spaced and radially protruding guiding projections which are provided with upwardly exposed beveled surfaces. The key switch assembly also includes a key top member displaceably coupled to the key switch socket member which is formed with an axially extended key stem. The key stem is coaxially received through the receiving bore of the key switch socket member and includes an outer surface portion on which are formed a pair of axially extended guiding rails slidably engaged respectively by the guiding projections of the key switch socket member and a radially protruding guiding rib which slidably engages the guiding slot of the key switch socket member. A pair of resilient projections are provided on the key stem to resiliently engage respectively the guiding projections of the key switch socket member.

FIELD OF THE INVENTION 
The present invention relates to a key switch, more particularly, to an 
improved key switch which is user friendly and easy to install. 
DESCRIPTION OF PRIOR ART 
Referring to FIG. 1, an exploded perspective view for a conventional key 
switch is shown. In the conventional keyboard, the upper panel 10a is 
provided with a plurality of key switch socket 11a. The key switch socket 
11a has a hollow rectangular configuration for slidably receiving a key 
top 12a thereon. The bottom of the key top 12a is provided with a key stem 
13a having also a rectangular configuration. Each of the corners of the 
key stem 13a of the key top 12a is provided with a post 14a. A elastic 
plate 15a is further provided adjacent to the post 14a such that the key 
stem 13a can be readily and slidably engaged with the key switch socket 
11a. The post 14a serves a lubricator to reduce the frictional force 
between the key stem 13a and the key switch socket 11a. The key stem 13a 
may move up and down within the key switch socket 11a as it is depressed 
by a finger of a user. Consequently, the rubber base 16a disposed at lower 
portion of the key stem 13a my selectively actuate a switch disposed 
thereunder. 
Nevertheless, the matching clearance between the key stem 13a and the key 
switch socket 11a shall be precisely selected to ensure the key stem 13a 
may be readily moved with respect to the key switch socket 11a. If the 
clearance is not correctly selected or machined, the key stem 13a will be 
jammed within the key switch socket 11a. If the clearance is too large, 
the key stem 13a will roll and pitch with respect to the key switch socket 
11a. In this case, the assembling of the key stem 13a to the key switch 
11a will be difficult and a defective product will be resulted, i.e. the 
key stem 13a will be jammed within the key switch socket 11a or the key 
stem 13a will roll and/or pitch with respect to the key switch socket 11a. 
Consequently, the manufacturing cost is considerably increased. 
In light of this, there is still a room for improving the key switch. 
SUMMARY OF THE INVENTION 
It is the objective of this invention to provide an improved key switch 
structure wherein the problems encountered by the conventional key switch 
can be advantageously solved. 
In order to achieve the object set forth, the improved key switch structure 
made according to the present invention generally comprises a key switch 
socket and a key top. The key switch socket is integrally formed on the 
upper panel of the keyboard. The key switch socket has a cylindrical 
configuration defining a receiving space therein. The inner wall of the 
key switch socket is provided with a pair of fixed guiding projections 
directed inward. Each of the projections is further includes bevel 
surface. A key top which can be readily and slidably received within the 
key switch socket is provided. A key stem having cylindrical configuration 
is provided at the bottom portion of the key top wherein the key stem can 
be moved down and up within the key switch socket. The outer surface of 
the key stem is provided with a pair of guiding rails corresponding to the 
guiding projections of the key switch socket. The lower portion of the 
guiding rail is provided with a gap which in turn provides elasticity to 
the lower portion of the guiding rail. The inner lower end portion of the 
guiding rails is provided with an elastic projection. Wherein the key stem 
of the key top can be readily and slidably received within the key switch 
socket and guided by the guiding projection of the key switch socket and 
the guiding rails of the key stem. Since the guiding rails are inherited 
with elasticity, consequently, the guiding rails may stable the vertical 
movement of the key stop. On the other hand, the guiding rails may also 
contact with the guiding projections of the key switch socket, 
consequently, the jam therebetween can be advantageously avoided as the 
frictional force is reduced or eliminated. Furthermore, the rolling or 
pitching of the key stem respect to the key switch socket can also be 
avoided. In conclusion, the key top can be more easily installed onto the 
key switch socket without any problems encountered by the conventional one 
.

BRIEF DESCRIPTION OF NUMERALS 
11 upper panel of keyboard 
12 guiding projection 
13 bevel surface 
14 guiding slot 
20 key cap 
21 key stem 
22 guiding rail 
23 gap 
24 resilient projection 
25 curved surface 
26 guiding rib 
31 pressing portion 
40 membrane switch 
50 bottom plate 
10a upper panel of keyboard 
11a key switch socket 
12a key top 
13a key stem 
14a post 
15a resilient plates 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
Referring to FIGS. 2, 3, and 4, showing the key switch structure made 
according to the present invention in exploded perspective view, cross 
sectional view and top plan view. The key switch made according to the 
present invention generally comprises a key switch socket 10 and a key top 
20. The key switch socket 10 is integrally formed on the upper panel 11 of 
the keyboard. The key switch socket 10 has a cylindrical configuration 
defining a receiving space therein. The inner wall of the key switch 
socket 10 is provided with a pair of fixed guiding projections 12 directed 
inward. Each of the projections 12 is further includes bevel surface 13. 
The inner wall of the key switch socket 10 can be further provided with at 
least a guiding slot 14. In the preferred embodiment of the present 
invention, one guiding slot 14 is provided. 
A key top 20 can be readily and slidably received by the key switch socket 
10. A key stem 21 is provided at the bottom portion of the key top 20 and 
the key stein 21 can be moved down and up within the key switch socket 10 
when it is depressed by the finger of the user. The outer surface of the 
key stem 21 is provided with a pair of guiding rails 22 corresponding to 
the guiding projections 12 of the key switch socket 10. The lower portion 
of the guiding rail 22 is provided with a pair of gaps 23 directed 
downward. By this arrangement, the lower portion of the guiding rail 22 is 
provided with resiliency. The inner lower end portion of the guiding rails 
22 is thus provided with a resilient projection 24 having a curve surface 
25 thereof. The outer surface of the outer surface of the key stem 21 is 
provided with a guiding rib 26 corresponding to the guiding slot 14 of the 
key switch socket 10. By this arrangement, the key top 20 can be correctly 
install onto the key switch socket 10 without the possibility of mistake. 
The key stem 21 of the key top 20 is slidably received within the key 
switch socket 10 such that the guiding projections 12 of the key switch 
socket 10 is slidably engaged with the guiding rails 22 of the key stem 21 
and the guiding slot 14 of the key switch socket 10 is also cooperatively 
engaged with the guiding ribs 26 of the key stem 21 such that the key stem 
21 may move vertically down and up within the key switch socket 10. 
As clearly shown in FIG. 3, when the key top 20 is depressed, the key stem 
21 is moved downward such that the pressing portion 31 of the elastic 
actuating member 30 will actuate the membrane switch 40 disposed at the 
upper surface of the bottom plate 50, i.e. the switch is On. When the 
external force is released, the key top 20 is bounced back by the 
potential force of the elastic actuating member 30 such that the member 
switch 40 is resumed to opened position as the pressing portion 31 is 
removed therefrom, i.e. the switch is resumed to Off. By this arrangement, 
the member switch can be selectively switched on by the downward movement 
of the key stem 21 of the key top 20. Since the elastic actuating member 
30 and the membrane 40 are known to the skilled in the art, accordingly, 
not detailed description is given. 
Since the key switch socket 10 and the key stem 21 all have the cylindrical 
configuration which can be readily and centrally positioned. On the other 
hand, the key stem 21 can be readily guided for vertical movement within 
the key switch socket 10 by the help of the guiding projections 12 and the 
guiding rails 22. 
Besides, the key stem 21 can be further stabled for vertical movement by 
the guiding slot 14 and the guiding ribs 26. On the other hand, the 
guiding projection 12 of the key switch socket 10 is provided with bevel 
surface 13 and the guiding rails 22 and the resilient projection 24 are 
all with elasticity, consequently, the guiding projections 12 can be 
readily received within the guiding rails 22 of the key stem 21. In light 
of this, the assembling can be readily done. 
Besides, in use of the key switch of the present invention, when the key 
stem 21 is moved upward, the resilient projection 24 of the key stem 20 is 
limited by the guiding projection 12 of the key switch socket 10, 
accordingly, the key stem 21 will not escape from the key switch socket 
12. On the other hand, the resilient projection 24 is provided with curve 
surface 25 which serves as a buffer, consequently, the noise generated 
from contact between the resilient projection 24 and the guiding 
projection 12 can be reduced or even eliminated. 
Since the guiding rails 22 are provided with a resilient structure, 
consequently, the guiding rails 22 may stable the vertical movement of the 
key stop 21. On the other hand, the guiding rails 22 may also contact with 
the guiding projections 12 of the key switch socket 10, consequently, the 
jam therebetween can be advantageously avoided as the frictional force is 
reduced or eliminated. Furthermore, the rolling or pitching of the key 
stem 21 respect to the key switch socket 10 can also be avoided. In 
conclusion, the key top 20 can be more easily installed onto the key 
switch socket 10 without any problems encountered by the conventional one. 
While particular embodiment of the present invention has been illustrated 
and described, it would be obvious to those skilled in the art that 
various other changes and modifications can be made without departing from 
the spirit and scope of the invention. It is therefore intended to cover 
in the appended claims all such changes and modifications that are within 
the scope of the present invention.