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Mobile Phone Patent Abstract
A key button switch structure for use in a handheld mobile phone,
comprises an input button 1 having a push-down pressure transmitting
projection A1 and a button inclination preventing projection B 3
both projected from a bottom surface of the input button, integrally
with the input button. Two electrodes A9 and B 10 are formed on
a substrate 8 fixed to a body casing 6. A dome-like switch contact
7 is provided to be pushed down by the push-down pressure transmitting
projection A1 of the input button when the input button is depressed,
thereby to electrically contact both the two electrodes. Thus, since
the button inclination preventing projection B 3 is provided, even
in the case that an action center line of the dome-like switch contact
is not coincident with an input pressure center line of the input
button, when the input button is depressed, the electrodes A9 and
B 10 formed on the substrate 8 are surely electrically interconnected
by the dome-like switch contact effectively uniformly collapsed
by the push-down pressure transmitting projection A1 of the input
button.
Mobile Phone Patent Claims
What is claimed is
1. A key button switch structure comprising: an input button having
a first projection, two electrodes formed on a substrate, and a
dome-like switch contact to be pushed down by said first projection
of said input button when said input button is depressed, thereby
to electrically contact both said two electrodes, wherein said input
button further comprises means for preventing inclination of said
input button when an action center line of said dome-like switch
contact is not coincident with an input pressure center line of
said input button and said input button is depressed, wherein said
means for preventing inclination comprises a second projection that
is spaced from said first projection and that contacts said substrate
when said input button is depressed, and wherein said input button
has a bottom surface that is sloped continuously from a distal end
of said first projection to a base of said second projection.
2. A key button switch structure comprising: an input button having
a first projection on a bottom surface of said input button; two
electrodes on a substrate; a dome-like switch contact arranged to
be pushed down by said first projection when said input button is
depressed, thereby to electrically contact both said two electrodes;
and a button inclination preventing projection on the bottom surface
of said input button, wherein said bottom surface is sloped continuously
from a distal end of said first projection to a base of said button
inclination preventing projection.
3. A key button switch structure comprising: an input button having
two projections spaced apart on a bottom surface of said input button;
two electrodes on a substrate; and a dome-like switch contact arranged
to be pushed down by one of said two projections when said input
button is depressed and the other of said two projections contacts
said substrate, so that said dome-like switch contact electrically
contacts both said two electrodes, wherein said bottom surface is
sloped continuously from a distal end of said one projection to
a base of said other projection.
4. The key button switch structure of claim 1, wherein said first
projection extends a same distance from said bottom surface as said
second projection.
Mobile Phone Patent Description
BACKGROUND OF THE INVENTION
The present invention relates to a key button structure for use
in a handheld mobile phone and its similar instrument, and more
specifically to a key button switch structure which can be incorporated
in a handheld mobile phone and its similar instrument, and which
comprises an input button having a projection, two electrodes formed
on a substrate, and a dome-like switch contact to be pushed down
by the projection of the input button when the input button is depressed,
thereby to electrically contact both the two electrodes, and a method
for forming such a key button structure.
Referring to FIG. 8, there is shown a diagrammatic section view
of one example of this type key button switch structure realized
in the prior art. The shown example includes an input button 21
having a projection 22, two electrodes A 29 and B 30 formed on a
substrate 28, and a dome-like switch contact 27, which are located
as shown. The input button 21 is formed integrally with a button
connection part 25 so that when the input button 21 is depressed,
the projection 22 pushes down the dome-like switch contact 27 to
cause the dome-like switch contact 27 to electrically contact both
the two electrodes A 29 and B 30.
FIG. 8 illustrates a typical example of the above mentioned prior
art key button switch structure in which a center line 31 of the
input button 21 is coincident with a center line 32 of the dome-like
switch contact 27. Accordingly, when a depressing pressure or force
is applied to the input button 27, the dome-like switch contact
27 is collapsed in an ideal fashion as shown in FIG. 9, with the
result that an electrical interconnection is obtained between the
two electrodes A 29 and B 30. In FIG. 9, the arrows "a"
and "b" diagrammatically illustrate the input pressure.
On the other hand, referring to FIG. 10, there is a shown a diagrammatic
sectional view illustrating an imaginary prior art example imaged
by the inventors, in which the center line 31 of the input button
21 is not coincident with the center line 32 of the dome-like switch
contact 27. When the depressing pressure is applied to the input
button 21, since the center line 31 of the input button 21 is deviated
from the center line 32 of the dome-like switch contact 27, the
input button 21 is inclined in a direction opposite to the deviating
direction of the dome-like switch contact 27 from the input button
21 as shown in FIG. 11, with the result that the dome-like switch
contact 27 is pushed down from an slant upper position. Furthermore,
a center of a depressing force transmitting region is shifted to
the neighborhood of a point of action 35 shown in FIG. 11, so that
the dome-like switch contact 27 is not sufficiently collapsed.
In the prior art structure, therefore, it is an indispensable condition
to align respective center lines of three parts, namely, the input
button 21, the projection 22, and the dome-like switch contact 27.
The reason for this is that, since the prior art has the structure
of electrically interconnecting the electrodes A 29 and B 30 by
the dome-like switch contact 27, a depression of a center of the
dome-like switch contact 27 in a vertical direction is a necessary
condition for deforming the dome-like switch contact 27 in an ideal
fashion.
Because of a structure restriction of the dome-like switch contact,
if a deviation in a depressing force applying position and angle
exceeds a given range of tolerance, the pushing pressure applied
to the dome-like switch contact 27 from the input button cannot
sufficiently overcome rigidity of the dome-like switch contact 27,
so that the dome-like switch contact 27 is not sufficiently deformed,
with the result that the contact becomes insufficient or poor.
The dome-like switch contact is effective in thinning the input
button structure. However, the location of the input buttons greatly
depends upon the position of the dome-like switch contacts located
on the substrate. Therefore, the layout of the dome-like switch
contacts restricts changes in appearance and precludes easy model
changes. Thus, use of common parts and the degree of freedom in
appearance are hindered.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide
a key button switch structure which has overcome the above mentioned
problems of the prior art.
Another object of the present invention is to provide a key button
switch structure which can be incorporated in a handheld mobile
phone and its similar instrument and which never hinders the use
of common parts and the degree of freedom in appearance design.
The above and other objects of the present invention are achieved
in accordance with the present invention by a key button switch
structure for use in a handheld mobile phone and its similar instrument,
the key button switch structure comprising an input button having
a projection, two electrodes formed on a substrate, and a dome-like
switch contact to be pushed down by the projection of the input
button when the input button is depressed, thereby to electrically
contact both the two electrodes, wherein the input button is so
configured to uniformly transmit a push-down pressure applied to
the input button, from a bottom surface of the projection of the
input button to the dome-like switch contact in the case that an
action center line of the dome-like switch contact is not coincident
with an input pressure center line of the input button.
Specifically, the input button includes a push-down pressure transmitting
projection and a button inclination preventing projection formed
on a bottom surface of the input button, integrally with the input
button.
Preferably, the input button also includes a recess formed in the
bottom surface of the input button, at a side of the push-down pressure
transmitting projection opposite to a button inclination preventing
projection side.
According to another aspect of the present invention, there is
provided a method for forming a key button switch structure for
use in a handheld mobile phone and its similar instrument, the method
including the steps of forming an input button having a projection,
forming two electrodes on a substrate, and providing a dome-like
switch contact to be pushed down by the projection of the input
button when the input button is depressed, thereby to electrically
contact both the two electrodes, wherein the input button is so
configured to uniformly transmit a push-down pressure applied to
the input button, from a bottom surface of the projection of the
input button to the dome-like switch contact in the case that an
action center line of the dome-like switch contact is not coincident
with an input pressure center line of the input button.
Specifically, the forming of the input button includes forming
the input button integrally with a push-down pressure transmitting
projection and a button inclination preventing projection both projected
from a bottom surface of the input button.
Preferably, the forming of the input button also includes formation
of a recess in the bottom surface of the input button, at a side
of the push-down pressure transmitting projection opposite to a
button inclination preventing projection side.
The above and other objects, features and advantages of the present
invention will be apparent from the following description of preferred
embodiments of the invention with reference to the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a partial front view for diagrammatically illustrating
an input button array section of a front part of a handheld mobile
phone having a first embodiment of the key button switch structure
in accordance with the present invention;
FIG. 2 is an enlarged partial front view for diagrammatically illustrating
one input button shown in FIG. 1;
FIG. 3 is a view similar to FIG. 2 but illustrating a condition
in which a body casing and the input button are removed so that
a substrate becomes viewable;
FIG. 4 is a diagrammatic sectional view taken along the line X1-X2
in FIGS. 2 and 3, for illustrating a sectional structure of the
first embodiment of the key button switch structure in accordance
with the present invention;
FIG. 5 is a view similar to FIG. 4 but illustrating a condition
that the input button is depressed;
FIG. 6 is a view similar to FIG. 4 but illustrating a second embodiment
of the key button switch structure in accordance with the present
invention;
FIG. 7 is a view similar to FIG. 6 but illustrating a condition
that the input button is depressed;
FIG. 8 is a diagrammatic section view of one input button switch
in one example of the prior art key button switch structure in which
the center line of the input button is coincident with the center
line of the dome-like switch contact;
FIG. 9 is a view similar to FIG. 8 but illustrating a condition
that the input button is depressed;
FIG. 10 is a diagrammatic sectional view illustrating an imaginary
prior art key button switch structure in which the center line of
the input button is positioned off the center line of the dome-like
switch contact; and
FIG. 11 is a view similar to FIG. 10 but illustrating a condition
that the input button is depressed.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, there is shown a partial front view for diagrammatically
illustrating an input button array section of a front part of a
handheld mobile phone having a first embodiment of the key button
switch structure in accordance with the present invention. As shown
in FIG. 1, a plurality of input buttons 1 are located in a front
face of a body casing 6 of the handheld mobile phone.
FIG. 2 is an enlarged partial front view for diagrammatically illustrating
one input button shown in FIG. 1, and FIG. 3 is a view similar to
FIG. 2 but illustrating a condition in which the body casing 6 and
the input buttons 1 are removed so that a substrate becomes viewable.
As seen from FIG. 3, a dome-like switch contact 7 is located on
a substrate 8 which is mounted in the body casing (not shown in
FIG. 3 but shown in FIG. 2).
Referring to FIG. 4, there is shown a diagrammatic sectional view
taken along the line X1-X2 in FIGS. 2 and 3, for illustrating a
sectional structure of the first embodiment of the key button switch
structure in accordance with the present invention.
In FIG. 4, the substrate 8 and the body casing 6 of the handheld
mobile phone are fixed to each other, so that a positional relation
between the substrate 8 and the body casing 6 never changes. As
shown in FIG. 4, the input button 1 has an input pressure receiving
front face 1A exposed through an opening 6B formed in a front panel
6A of the body casing 6. The input button 1 also has a projection
A 2 and a projection B 3 formed on a bottom face which is opposite
to the pressure receiving front face 1A and which opposes to the
substrate 8. A bottom face of the projection A 2 acts as a face
for transmitting an input pressure or force received by the input
button 1 to a dome-like switch contact 7. The input button 1 is
integral at its side wall with a button connection part 5 through
a flexible junction 5A, and the shown input button 1 and not-shown
other input buttons are integral with the button connection part
5 in the form of an integral sheet. For example, the input button
1 including the projection A 2 and a projection B 3 and the button
connection part 5 can be integrally formed of plastics or a rubber
having a relative high hardness.
As seen from FIG. 3 and FIG. 4, the dome-like switch contact 7
is formed of a thin sheet in a dome shape having a function of a
leaf spring or disk spring and formed of a metal or a resin having
a good electrically conductivity. Regardless of whether or not the
dome-like switch contact 7 is collapsed, the dome-like switch contact
7 is in ceaseless contact with an electrode A 9 (outer electrode
of annular electrode) formed on the substrate 8.
Although not shown for simplification of the drawing, the dome-like
switch contact 7 is covered with a thin vinyl-based sheet so that
the dome-like switch contact 7 is retained or held on the substrate
8 and is in ceaseless contact with the electrode A 9. An electrode
B 10 (center electrode or point electrode) is formed on the substrate
8 to be positioned at a center of the electrode A 9, so that the
electrode B 10 is never in contact with the dome-like switch contact
7 when the dome-like switch contact 7 is in a non-collapsed condition.
Thus, when the input button 1 is depressed to push down a center
top portion of the dome-like switch contact 7 by the bottom face
of the projection A 2, the dome-like switch contact 7 is collapsed
to physically contact both the electrode A 9 and the electrode B
10, thereby to electrically interconnect between the electrode A
9 and the electrode B 10.
Referring to FIG. 5, there is shown a view similar to FIG. 4 but
illustrating a condition that the input button 1 is depressed.
The shown embodiment is based on the premise that a center line
11 of the input button 1 is positioned off a center line 12 of the
dome-like switch contact 7, as seen from FIG. 4. Under this premise,
the projection B3 is formed at a side edge opposite to the deviating
direction of the center line 12 of the dome-like switch contact
7 from the center line 11 of the input button 1 as shown in FIG.
4, in order to prevent the inclination of the input button when
the input button 1 is depressed to displace toward the substrate
8.
In order to uniformly transmit the push-down pressure or force
applied to a center part of the input button 1, to the bottom surface
of the projection A 2 having a center point deviated from the center
line 11 of the input button 1, an inclined part 14 is formed on
a side of the projection A 2 near to the projection B 3, as shown
in FIG. 4. With this arrangement, since the input button 1 is supported
at two points given by the projection A 2 and the projection B3,
the shape of the side of the input button 1 facing the substrate
8 is shaped to be asymmetrical so as to give an increased rigidity
to the input button 1, thereby to prevent the portion between the
projection A 2 and the projection B3 from being bowed by the depressing
pressure or force.
As seen from the above, the key button switch structure of the
shown embodiment is featured in that since a bottom surface of the
input button is formed with a push-down pressure transmitting projection
(projection A 2) and a button inclination preventing projection
(projection B 3), and since the rigidity of the input button 1 is
enhanced or stiffened, even in the case that the action center line
12 of the dome-like switch contact 7 is not coincident with the
input pressure center line 11 of the input button 1, it is possible
to prevent poor electrical contact between the electrodes A 9 and
B 10 when the input button is depressed.
Referring to FIG. 6, there is shown a view similar to FIG. 4 but
illustrating a second embodiment of the key button switch structure
in accordance with the present invention. In FIG. 6, elements corresponding
to those shown in FIGS. 4 and 5 are given the same reference numbers,
and explanation will be omitted for simplification of the description.
As seen from comparison between FIG. 4 and FIG. 6, the second embodiment
of the key button switch structure shown in FIG. 6 includes a recess
4 at a side of the projection A 2 opposite to the inclined part
14.
In the key button switch structure shown in FIG. 4, the projection
B 3 is formed to prevent inclination of the input button 1, and
since the input button 1 is supported at the two points given by
the projection A 2 and the projection B3, the inclined part 14 is
formed to extend from the projection A 2 to a base of the projection
B3 so as to give an increased rigidity, thereby to prevent the portion
between the projection A 2 and the projection B3 from being bowed
by the depressing pressure or force. As a result, when the input
button 1 is depressed, the inclination of the input button 1 is
prevented as shown in FIG. 5. However, the center of the transmission
of the input depressing pressure is still at the neighborhood of
a point of action 15, and therefore, the collapse of the dome-like
switch contact 7 often becomes unstable because of an error in manufacturing.
In order to overcome this problem, the recess 4 is formed in the
embodiment shown in FIG. 6. FIG. 7 is a view similar to FIG. 6 but
illustrating a condition that the input button 1 is depressed. The
example shown in FIG. 7 is different from the example shown in FIG.
5 in that since the recess 4 is formed, an apparent boundary plane
is created at a left side of the projection A 2 in the drawing,
so that the rigidity is increased in the neighborhood of the boundary
plane, with the result that the efficiency of the transmission of
the input depressing pressure or force is elevated. Thus, the pressure
transmitted to the bottom surface of the projection A2 shown in
FIG. 6 is uniformized over the bottom surface of the projection
A2, so that an ideal push-down pressure or force is transmitted
to the dome-like switch contact 7, and therefore, a good electrical
conduction is surely obtained between the electrode A9 and the electrode
B10.
As seen from the above, the above mentioned first and second embodiments
of the key button switch structure in accordance with the present
invention is characterized in that in a key button switch which
has a large depressing area and which can be used in a handheld
mobile phone and the like, since the push-down pressure transmitting
projection and the button inclination preventing projection are
formed on and integrally with the bottom surface of the input button,
the following advantages can be obtained: (1) It is possible to
improve the thinning and the weight-reducing of an instrument having
the key button switch structure; (2) It is possible to increase
the extent of utilization of existing parts, to increase the yield
of production, to reduce the size of the instrument, to facilitate
the handling, to freely design the size and the specification, and
to increase the degree of freedom in appearance design; and (3)
It is possible to improve a working procedure until the key button
switch structure is incorporated into the body casing.
The present invention has been explained with reference to the
handheld mobile phone having the key button switch structure in
accordance with the present invention. However, the present invention
is in no way limited to the key button switch structure of the handheld
mobile phone, but can be applied to any instrument and apparatus
which can have the key button switch structure.
As seen from the above, according to the present invention, even
in the case that the action center line of the dome-like switch
contact is not coincident with the input pressure center line of
the input button, the inclination of the input button is prevented,
so that the variation in the contact angle between the bottom surface
of the push-down pressure transmitting projection and the contacting
region of the dome-like switch contact is minimized, thereby to
uniformly transmit the push-down pressure applied to the input button,
from the bottom surface of the push-down pressure transmitting projection
of the input button to the dome-like switch contact.
Furthermore, since the recess is formed at the side of the push-down
pressure transmitting projection opposite to the input button center
line side, the rigidity of the input button in the periphery of
the push-down pressure transmitting projection is adjusted, to uniformize
the push-down pressure applied from the bottom surface of the push-down
pressure transmitting projection. Therefore, even if the center
line of the dome-like switch contact is deviated from the center
line of the input button, it is possible to surely contact the dome-like
switch contact to both the electrodes A and B.
Accordingly, it is possible to improve the thinning and the weight-reducing
of an instrument having the key button switch structure which has
a large depressing area and which can be used in a handheld mobile
phone and the like.
It is possible to increase the extent of utilization of existing
parts, to increase the yield of production, to reduce the size of
the instrument, to facilitate the handling, to freely design the
size and the specification, and to increase the degree of freedom
in appearance design; and
It is possible to improve a working procedure until the key button
switch structure is incorporated into the body casing.
The invention has thus been shown and described with reference
to the specific embodiments. However, it should be noted that the
present invention is in no way limited to the details of the illustrated
structures but changes and modifications may be made within the
scope of the appended claims. |