The present invention relates to the area of switches which are used for making and breaking
of electrical connections between electrical wires. In particular, the invention relates to a push
type switch assembly that can be used for automotive applications.
Background of the Invention:
Switches are used to make electrical connections between electrical wires. Many electrical
system failures result from bad contacts of electrical switches. The bad contacts may result
from contamination at contact surfaces or terminals, or may result from wearing of the
contact surfaces and/or terminals.
A variety of pivotable switches have been provided that try to incorporate a self-cleaning
mechanism. For instance, Japanese Patent No. JP3662659 discloses a pivotable push button
switch that includes a knob which can be actuated by a user. The knob is partially housed
within the housing and upon actuation exhibits a pivotal movement with respect to a pivot
axis. A spring is provided between the housing and the knob to provide a restoring force to
the knob. The housing is provided with an input terminal and an output terminal. A bottom
potion of knob includes a moving contact element. In this case, the moving contact element is
NOT in constant electrical contacting relationship with either the input terminal or the output
terminal. In this case, a tip of the moving contact element has a U-shaped bottom surface
which upon actuation, butts the input and the output terminals thereby providing an electrical
path between the input and the output terminals. In this case, the moving contact element in
addition to merely butting the input and the output terminals, also slides over the input and
the output terminals and thus, can be said to have a self-cleaning construction.
However, a push button switch that incorporates a self-cleaning construction is difficult to
make. At best, push button switches that break oxide layer formed on the top surface of the
contacts have been developed. In a typical construction, the fixed contact is located above the
moving contact and the moving contact is made to strike hard the fixed contact thereby
breaking the oxide layer.
It has been felt that the constructions of the prior art push button switch incorporating self- cleaning construction are having one or another known disadvantage. Thus, there exists a
need to provide a push button switch which is simple in terms of its construction, which is
easy to manufacture, which can be manufactured at a reasonable price, which occupies less
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space, which has high precision and which can be used for low current applications and
which incorporates self-cleaning construction.
SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts in a simplified format that are
further described in the detailed description of the invention. This summary is neither
intended to identify key or essential inventive concepts of the invention, and nor is it intended
for determining the scope of the invention.
In accordance with an embodiment, the present invention provides a push type switch
assembly, comprising a pair of fixed terminals. The switch assembly further comprises a push
button adapted to exhibit a to-and-fro motion with respect to the pair of fixed terminals in
response to receiving an actuating force. The switch assembly furthermore comprises a
movable member disposed between the pair of fixed terminals and the push button, the
movable member being adapted to make a butt contact with the pair of fixed terminals and
thereafter glide over the pair of fixed terminals.
To further clarify advantages and features of the present invention, a more particular
description of the invention will be rendered by reference to specific embodiments thereof,
which is illustrated in the appended drawings. It is appreciated that these drawings depict
only typical embodiments of the invention and are therefore not to be considered limiting of
its scope. The invention will be described and explained with additional specificity and detail
with the accompanying drawings.
BRIEF DESCRIPTION OF THE FIGURES:
In order that the invention may be readily understood and put into practical effect, reference
will now be made to exemplary embodiments as illustrated with reference to the
accompanying drawings, where like reference numerals refer to identical or functionally
similar elements throughout the separate views. The figures together with a detailed
description below, are incorporated in and form part of the specification, and serve to further
illustrate the embodiments and explain various principles and advantages, in accordance with
the present invention where:
Figure 1 illustrates an exploded view of the push type switch assembly in accordance with an
embodiment of the present invention; and
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Figure 2(A) illustrates a front view of the movable member in accordance with an
embodiment of the invention;
Figure 2(B) illustrates a perspective view of the movable member in accordance with an
embodiment of the invention;
Figure 3(A) illustrates the push type switch assembly in a non-actuated state;
Figure 3(B) illustrates the push type switch assembly in an actuated state wherein the
movable member makes a butt contact with the pair of fixed terminals;
Figure 3(C) illustrates the push type switch assembly in an actuated state wherein the
movable member glides over the pair of fixed terminals;
Figure 4(A) illustrates the positional relationship between the movable member and the fixed
terminals when the push button is in a non-actuated state, which corresponds to Figure 3(A);
Figure 4(B) illustrates the movable member making a butt contact with the pair of fixed
terminals in response to the push button being actuated, which corresponds to Figure 3(B);
and
Figure 4(C) illustrates the movable member gliding over the pair of fixed terminals in
response to further continued actuation of the push button, which corresponds to Figure 3(C);
It may be noted that to the extent possible, like reference numerals have been used to
represent like elements in the drawings. Further, skilled artisans will appreciate that elements
in the drawings are illustrated for simplicity and may not have been necessarily been drawn
to scale. For example, the dimensions of some of the elements in the drawings may be
exaggerated relative to other elements to help to improve understanding of aspects of the
present invention. Furthermore, the one or more elements may have been represented in the
drawings by conventional symbols, and the drawings may show only those specific details
that are pertinent to understanding the embodiments of the present invention so as not to
obscure the drawings with details that will be readily apparent to those of ordinary skill in the
art having benefit of the description herein.
Detailed Description of the Invention:
For the purpose of promoting an understanding of the principles of the invention, reference
will now be made to the embodiment illustrated in the drawings and specific language will be
used to describe the same. It will nevertheless be understood that no limitation of the scope of
the invention is thereby intended, such alterations and further modifications in the illustrated
device, and such further applications of the principles of the invention as illustrated therein
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being contemplated as would normally occur to one skilled in the art to which the invention
relates.
It will be understood by those skilled in the art that the foregoing general description and the
following detailed description are explanatory of the invention and are not intended to be
restrictive thereof.
As used in the description herein and throughout the claims that follow, the meaning of “a,”
“an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also,
as used in the description herein, the meaning of “in” includes “in” and “on” unless the
context clearly dictates otherwise.
Reference throughout this specification to “an aspect”, “another aspect” or similar language
means that a particular feature, structure, or characteristic described in connection with the
embodiment is included in at least one embodiment of the present invention. Thus,
appearances of the phrase “in an embodiment”, “in another embodiment” and similar
language throughout this specification may, but do not necessarily, all refer to the same
embodiment.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a
non-exclusive inclusion, such that a device that comprises a list of steps does not include only
those steps but may include other steps not expressly listed or inherent to such process or
method. Similarly, one or more devices or sub-systems or elements or structures or
components proceeded by "comprises... a" does not, without more constraints, preclude the
existence of other devices or other sub-systems or other elements or other structures or other
components or additional devices or additional sub-systems or additional elements or
additional structures or additional components.
As used herein, and unless the context dictates otherwise, the terms "coupled to", “connected
to”, “operably connected to”, “operatively connected to” are intended to include both direct
connection / coupling (in which two elements that are coupled / connected to each other
contact each other) and indirect coupling / connection (in which at least one additional
element is located between the two elements). Therefore, the terms "coupled to" and "coupled
with" are used synonymously. Similarly, the terms “connected to” and “connected with” are
used synonymously.
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Unless otherwise defined, all technical and scientific terms used herein have the same
meaning as commonly understood by one of ordinary skilled in the art to which this invention
belongs. The device, methods, and examples provided herein are illustrative only and not
intended to be limiting.
The use of any and all examples, or exemplary language (e.g. “such as”) provided with
respect to certain embodiments herein is intended merely to better illuminate the invention
and does not pose a limitation on the scope of the invention otherwise claimed. No language
in the specification should be construed as indicating any non-claimed element essential to
the practice of the invention.
Groupings of alternative elements or embodiments of the invention disclosed herein are not
to be construed as limitations. Each group member can be referred to and claimed
individually or in any combination with other members of the group or other elements found
herein. One or more members of a group can be included in, or deleted from, a group for
reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the
specification is herein deemed to contain the group as modified thus fulfilling the written
description of all Markush groups used in the appended claims.
Embodiments of the present invention will be described below in detail with reference to the
accompanying drawings.
Referring to Figure 1, which is an exploded view of the push type switch assembly (10) in
accordance with an embodiment of the invention. The push type switch assembly (10)
comprises a pair of fixed terminals (12, 14). The push type switch assembly (10) further
comprises a push button (16) adapted to exhibit a to-and-fro motion with respect to the pair of
fixed terminals (12, 14) in response to receiving an actuating force. The push type switch
assembly (10) further comprises a movable member (18) disposed between the pair of fixed
terminals (12, 14) and the push button (16), the movable member (18) being adapted to make
a butt contact with the pair of fixed terminals (12, 14) and thereafter glide over the pair of
fixed terminals (12, 14).
In an embodiment of the invention, the push type switch assembly (10) further comprises a
housing (20) and a cover (22) together defining an internal space for accommodating the pair
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of fixed terminals (12, 14) and the movable member (18). The housing (20) is provided with
an aperture (24) to allow a top portion of the push button (16) to traverse there-through.
In another embodiment of the invention, the push type switch assembly (10) further
comprises a spring member (26) disposed between a bottom portion of the push button (16)
and the cover (22) to normally maintain the movable member (18) away from the pair of
fixed terminals (12, 14). In yet another embodiment of the invention, the bottom portion of
the push button (16) is adapted to fixedly hold the movable member (18). Although not visible, an internal space of the housing (20) may be provided with a guiding
means for guiding the push button (16). The push type switch assembly (10) further
comprises a sealing element (28) that co-operates with the housing (20) to prohibit ingress of
dust, moisture and other contaminants via the aperture (24) provided in the housing (20).
Now referring to Figure 2(A) and Figure 2(B), there is shown a front view and a perspective
view of the movable member (18) in accordance with an embodiment of the invention. The
movable member (18) comprises first portions (30) located at the extremities and a base
portion (32) located between the first portions (30).
In an embodiment of the invention, the first portions (30) are in the form of curved surfaces.
In a preferred aspect of the invention, the base portion (32) is of deformable nature. Particularly, the base portion (32) is adapted to deform under application of force thereupon
and when the forces ceases to exist, is adapted to return back to its natural state.
In particular, the base portion (32) comprises a joining portion (34) which is located at about
a central location of the base portion (32). The joining portion (34) is used for fixedly holding
the movable member (18) to the bottom portion of the push button (16). The joining portion
(34) may be substantially planar and parallel to the pair of the fixed terminals (12, 14). The
base portion (32) furthermore comprises a pair of sloping / slanting / curved portions (36) that
interconnect the joining portion (34) with the first portions (30).
Now referring to Figures 3(A), 3(B) and 3(C), there is illustrated a sectional view of the push
type switch assembly (10) in different functional states. In Figure 3(A), the push type switch
assembly (10) is in non-actuated state and hence, the push button (16) is shown to protrude to
a larger distance outside the housing (20) and the movable member (18) is shown to be away
from the pair of fixed terminals (12, 14). Hence, the switch is said to be in OFF state. In
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response to the push button (16) receiving an actuating force in the direction shown by arrow
marked as “A”, the push button (16) together with the movable member (18) exhibits a
movement along the “A” direction and reaches to a state as shown in Figure 3(B).
In Figure 3(B), the movable member (18) makes a butt-contact with the pair of fixed
terminals (12 and 14) and hence, the switch comes to an ON state. It can be seen in Figure
3(B) that the bottom portion of the push button (16) is provided with a first pillar structure
(38) and the cover (24) is provided with a second pillar structure (40) which are separated
from each other or in other words, have not come in abutting relationship yet. Thus, the push
button (16) can be still actuated in the direction shown by arrow marked as “B”. However,
after the movable member (18) makes a butt-contact with the pair of fixed terminals, the
movable member, cannot exhibit any movement along the “B” direction.
Now referring to Figure 3(C), it can be seen that the first pillar structure (38) is in abutting
relationship with the second pillar structure (40) and hence, push button (16) cannot hereafter
exhibit movement along the “B” direction. Now during the transition between the states as
shown in Figure 3(B) and 3(C) i.e. transition between the movable member (18) making butt- contact with the pair of fixed terminals (12 and 14) and the first pillar structure (38) coming
to an abutting relationship with the second pillar structure (40), the movable member (18)
glides over the surface of the pair of fixed terminals (12, 14). Thus, the movable member (18)
first makes a butt-contact with the pair of fixed terminals (12 and 14) and thereafter glides
over the surface of the pair of fixed terminals. It may be noted that when the first pillar
structure (38) comes in an abutting relationship with the second pillar structure (40), the
gliding of the movable member (18) over the surface of the pair of fixed terminals is also
prohibited. Thus, coming of the first pillar structure in abutting relationship with the second
pillar structure defines a maximum gliding of the movable member over the surface of the
pair of fixed terminals.
Now referring to Figures 4(A), 4(B) and 4(C), positional relationships between the movable
member and the pair of fixed terminals is illustrated for the different functional states of the
push type switch assembly (10) shown in Figures 3(A) to 3(C).
In particular, Figure 4(A) shows the positional relationships between the movable member
(18) and the pair of fixed terminals (12, 14) when the push type switch assembly (10) is in a
state as shown in Figure 3(A) i.e. in OFF state. Here it can be seen that the movable member
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(18) is physically separated from the pair of fixed terminals (12, 14). In response to the push
button (16) receiving an actuating force, the movable member (18) exhibits movement along
a direction shown by arrow marked as “A” and reaches to a state as shown in Figure 4(B). It
can be seen in Figure 4(A) that movable member (18) is shown to have an effective length
(length between the two contact making points on the two first portions (30)) of “L1”.
In Figure 4(B), the movable member (18) and more particularly, the first portions (30) of the
movable member (18) are shown to make butt-contact with the pair of fixed terminals (12
and 14). In particular, the first portions (30) of the movable member (18) are shown to make
butt-contact at an initial location (42) on each of the fixed terminals (12 and 14). Even in
Figure 4(B) that movable member (18) has an effective length of “L1”.
Once the push button (16) is further actuated in the direction shown by arrow marked as “B”,
the movable member (18) cannot exhibit any movement along the “B” direction but rather
starts exhibiting deformation along a direction shown by arrow marked as “C”. In particular,
the pair of sloping / slanting / curved portions (36) that interconnect the joining portion (34)
with the first portions (30) now deforms to become substantially planar and parallel to the
pair of the fixed terminals (12, 14). Hence, it can be seen that the length between the two
contact making points on the two first portions (30) becomes equal to “L2”, which is greater
than “L1”.
Now referring to Figure 4(C), when the sloping / slanting / curved portions (36) are in the
process of deforming, the first portions (30) of the movable member (18) glide over the
surface of the pair fixed terminals i.e. they glide from the initial location (42) to a final
location (44). When the first portions (30) are gliding from the initial location (42) to a final
location (44), the first portions (30) wipe a portion of the surface of the pair of fixed terminals
(12, 14).
Thus, it can be seen that the switch constructed in accordance with the teachings of the
present invention breaks the oxide layer formed on the top surface of the pair of fixed
terminals while making the butt-contact and pushes oxide particles and other contaminants
that may be present on the surface of pair of fixed terminals to a corner location (where the
hindrance caused may be said to be minimum).
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Apart from the above, it can be seen that the number of components forming part of the
switch is very less. Actually speaking, there are only 7 parts (including the sealing member).
Also, it becomes possible to manufacture the fixed terminals and cover together and hence,
the number of components becomes substantially less. This result in substantial cost benefit,
ease of manufacturing, reduction in the time spent in assembling and various other
advantages.
While specific language has been used to describe the disclosure, any limitations arising on
account of the same are not intended. As would be apparent to a person in the art, various
working modifications may be made to the method in order to implement the inventive
concept as taught herein. The figures and the foregoing description give examples of
embodiments. Those skilled in the art will appreciate that one or more of the described
elements may well be combined into a single functional element. Alternatively, certain
elements may be split into multiple functional elements. Elements from one embodiment may
be added to another embodiment. For example, orders of processes described herein may be
changed and are not limited to the manner described herein. The scope of embodiments is by
no means limited by these specific examples. Numerous variations, whether explicitly given
in the specification or not, such as differences in structure, dimension, and use of material,
are possible. The scope of embodiments is at least as broad as given by the following claims.

WE CLAIM:

1. A push type switch assembly (10), comprising:
a pair of fixed terminals (12, 14);
a push button (16) adapted to exhibit a to-and-fro motion with respect to the
pair of fixed terminals (12, 14) in response to receiving an actuating force;
characterized by:
a movable member (18) disposed between the fixed terminals (12, 14) and the
push button (16), the movable member (18) being adapted to make a butt contact with
the pair of fixed terminals (12, 14) and thereafter glide over the pair of fixed terminals
(12, 14). 2. The switch assembly as claimed in claim 1, further comprising a housing (20) and a
cover (22) together defining an internal space for accommodating the pair of fixed
terminals (12, 14) and the movable member (18). 3. The switch assembly as claimed in claim 2, comprising a spring member (26)
disposed between a bottom portion of the push button (16) and the cover (22) to
normally maintain the movable member (18) away from the pair of fixed terminals
(12, 14). 4. The switch assembly as claimed in claim 3, wherein the bottom portion of the push
button (18) is adapted to fixedly hold the movable member (18). 5. The switch assembly as claimed in claim 2, wherein an internal space of the housing
(20) is provided with a guiding means for guiding the push button (18). 6. The switch assembly as claimed in claim 1, wherein the movable member (18)
comprises:
first portions (30) located at the extremities of the movable member (30), the
first portions (30) being in the form of curved surfaces; and
a base portion (32) located between the first portions (30), the base portion
(32) being deformable.
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7. The switch assembly as claimed in claim 6, wherein the first portions (30) are adapted
to make butt-contact with the pair of fixed terminals (12, 14) and thereafter glide over
the surface of the pair of fixed terminals. 8. The switch assembly as claimed in claim 7, wherein the first portions (30) are adapted
to wipe a portion of the surface of the pair of fixed terminals (12, 14) when gliding on
said surface.
9. The switch assembly as claimed in claim 8, wherein the bottom portion of the push
button (16) is provided with a first pillar structure (38) and the cover (22) is provided
with a second pillar structure (40) that comes into abutting relationship with each
other to define a maximum gliding of the movable member (18) over the surface of
the pair of fixed terminals (12, 14).