Keyboard allowing for simple, cost-effective production

Details Keyboard allowing for simple, cost-effective production Keyboard allowing for simple, cost-effective production

2002-09-25

2004-11-23

Colilla, Daniel J. (Department: 2854)

Typewriting machines

Key-board or key lever-actuating mechanism

Key-cap or key-stem structure

C400S472000

Reexamination Certificate

active

06821036

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to computer systems and other devices having keyboards and more particularly to keyboards. Even more particularly, the present invention relates to a simpler and more cost-effective way of designing and producing the keys on such keyboards.
BACKGROUND OF THE INVENTION
As is well-known, in various devices including personal computers (PC) and electronic desk calculators, a keyboard to be operated by a user is constructed so that each of a plurality of keys is capable of movement through an upstroke/downstroke (hereinafter referred to as “up/down movement” in this specification). The functions required of such keys include, in addition to a function of allowing the key top to move up and down, a function of operating a switch provided on a circuit board at a position below each key, and a function of returning the key top to the home position after allowing the key top to be depressed, and also include, as a function for enabling a user to feel improved key response when operating the key, a function of stopping the key from shifting in any direction other than the vertical direction when the key top moves up and down.
FIG. 6
shows an example of a known structure of a key having such functions. In
FIG. 6
are illustrated a key top
1
forming a key face, reference numeral
2
denotes an up/down mechanism which supports the key top
1
so that the key top
1
can move up and down, and reference numeral
3
denotes a rubber dome for returning the key top to the home position.
The up/down mechanism
2
is constituted by a pair of arms
4
and
5
, a top plate
6
, and a fixing member
7
. In this up/down mechanism
2
, the arms
4
and
5
are rotatably connected to each other by a shaft
4
a
so as to operate as a pantograph or scissor, thereby enabling movement in the up/down direction. The top plate
6
is rotatably connected at its one end to the arm
4
and slidably engages with the arm
5
at the other. The top plate
6
has a function of operating as an element for reinforcing the arms
4
and
5
when the arms
4
and
5
expand or contract, and a function of receiving the top end of the rubber dome
3
. The fixing member
7
slidably fixes the lower ends of the arms
4
and
5
on an unillustrated base plate.
The rubber dome
3
is made of an elastic material, which is a kind of rubber or the like. The rubber dome
3
is placed inside the up/down mechanism
2
and its top end is brought into abutment against the lower surface of the top plate
6
of the up/down mechanism
2
. A downwardly-projecting projection is provided on the reverse side of the top end of the rubber dome
3
to operate a switch in a membrane sheet (circuit board) provided on the unillustrated base plate.
In the thus-constructed key, when a user depresses the key top
1
, the up/down mechanism
2
operates so as to contract. The rubber dome
3
is thereby compressed and deformed to move its top end downward. With the downward movement of the top end, the unillustrated projection provided on the reverse side of the top end presses the switch, thereby enabling the key top
1
operation to be detected.
The compressed and deformed rubber dome
3
has a force for restoring its original shape. When the user stops pressing the key top
1
downward, the top plate
6
is moved upward by the restoring force of the rubber dome
3
to expand the up/down mechanism
2
, thereby returning the key top
1
to the home position.
There are problems associated with a key having the above-described construction in that the structure of the up/down mechanism
2
is particularly complicated and the parts cost and assembly cost are therefore high. As is well-known, a keyboard has a plurality of keys, assembly of the parts of each key is time-consuming, and the total number of parts is considerably large. Therefore it is important to solve the above-described problem.
The number of parts of the up/down mechanism
2
may, of course, be reduced in any number of ways. From the viewpoint of maintaining the desired stability of the key during up/down movement, however, it must be said that it is difficult to reduce the number of parts without sacrificing other desirable characteristics of the key—such as stability, feel, consistency, etc. Therefor, it is an object of the present invention to provide kays on a keyboard which provide a user with the desired feel and stability of current keyboards but which may be produced using fewer parts and at a lower cost.
SUMMARY OF THE INVENTION
The inventors of the present invention have studied eagerly with this object and found it effective to form a plurality of keys as one integral component. However, problems described below arise in a case where a plurality of keys are formed as one integral component.
As shown in FIG.
5
(
a
), in a case where keys are formed by combining a key member
11
and a cover
12
, a plurality of (e.g., two) key tops
11
a
formed on the key member
11
so as to project upward therefrom are fitted in holes
12
a
formed in the cover
12
.
Ordinarily, the above-described key member
11
and cover
12
are provided as molded resin components. Any combination of a plurality of components, including such molded resin components, entails a problem relating to a working error.
A predetermined tolerance is given on each of the distance P
1
between key tops
11
a
and the distance P
2
between the holes
12
a
determined at the time of resin molding. For example, in a case where a row of a plurality of keys is formed such that each of the distances P
1
and P
2
between the keys placed at the opposite ends exceeds 100 mm, a tolerance of typically ±0.25 mm exists. In this case, if the distance P
1
of the resin molded key member
11
includes a working error of −0.25 mm and if the distance P
2
of the cover
12
includes a working error of +0.25 mm, a total error of 0.50 mm exists between the two distances.
Then, when the key top
11
a
of the key member
11
is fitted around the hole
12
a
of the cover
12
shown in FIG.
5
(
b
), the center of the key top
11
a
is out of alignment with the center of the hole
12
a
, even though each of the key member
11
and the cover
12
has the accuracy within the tolerance.
If such a misalignment exists, interference may occur between the key top
11
a
and the hole
12
a
to impede the up/down movement of the key top
11
a
. To avoid this interference, a clearance is set between the outside diameter of the key top
11
a
and the inside diameter of the hole
12
a
by factoring in an error within the above-described tolerance.
However, a state where the amount of misalignment of the key top
11
a
with the hole
12
a
in one direction is so large that a portion of the gap
13
around the key cap
11
a
narrows or disappears, as shown in FIG.
5
(
b
), is undesirable in terms of appearance. For this reason, the clearance may be increased to ensure that the gap
13
is continuously formed along the entire perimeter of the key top
11
a
. From the keys with an increased clearance, however, a user may have the impression that the working accuracy of the entire PC is low. Also, the possibility of foreign objects or the like entering through the gap
13
is increased.
The above-described problems become more serious if the number of keys continuously arranged to form one integral component is increased or if the length of the integral component is increased.
The above-described problems can of course be solved if the working error at the time of molding of each of the key member
11
and the cover
12
is reduced. However, this is not an effective solution of the problems since use of means for reducing the working error of the molded resin components leads directly to a considerable increase in mold cost.
A computer system in accordance with the present invention provided by considering the above-described problems has a keyboard of a construction in which a plurality of keys arranged in a continuous row at least in one direction are supported on a frame having

Affiliated with

Also associated with

Rating

Keyboard allowing for simple, cost-effective production does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Keyboard allowing for simple, cost-effective production, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Keyboard allowing for simple, cost-effective production will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3362234