FIELD OF THE INVENTION
[0001] The present invention relates to a push switch used for various kinds of electronic
apparatuses, and, more particularly, the invention relates to a small push switch
having a long operation stroke.
BACKGROUND OF THE INVENTION
[0002] Conventionally, a switch disclosed in Japanese Patent Application Non-Examined Publication
No. H8-203380 is widely known. Hereinafter, the structure of the conventional push
switch as an example is described referring to Fig. 5 which shows the cross sectional
front view of the conventional switch, and to Fig. 6 which shows the exploded perspective
view of the same.
[0003] In Fig. 5 and Fig. 6, a resinous case 310 is formed to have a shape of a box having
an opening at the upper side thereof. On the inner side of the bottom of the case
310, a short fixed contact unit 320 having a terminal 321 and a long contact unit
330 having a terminal 331 are disposed.
[0004] A contact slip 340 is formed by bending a belt shaped elastic thin metal plate to
have a shape like a character of U. The contact slip 340 has an upward bent portion
341 at one end thereof. The other end of the contact slip 340 is formed to have two
leg portions 343 and 344. The two leg portions 343 and 344 are bent at the bent portions
342 as shown in Fig. 6. The two leg portions 343 and 344 have respective movable contact
portions 345 and 346 at the respective ends thereof. At around the bent portion 342,
a connecting portion 347 is formed for connecting the two leg portions 343 and 344.
The movable contact portions 345 and 346 are disposed in the case 310 in such a manner
as to touch the inner side of the bottom of the case 310.
[0005] A resinous cover 350 is disposed on the upper side of the case 310 in such a manner
as to close the upper side opening of the case 310. At one end of the cover 350 a
downward protrusion is formed. A supporting portion 351, viz., the front end of the
downward protrusion of the cover 350 presses downward the upward bent portion 341
of the contact slip 340, whereby the movable contact units 345 and 346 elastically
contact to the inner side of the bottom of the case 310 with predetermined pressing
force.
[0006] A resinous operation unit 360 is disposed in such a manner as to extend from the
space between the two leg portions 343 and 344 of the contact slip 340 to the outside
of the cover 350 through a hole 352 formed through the central portion of the cover
350. That is, the operation unit 360 is supported to be movable up and down by the
hole 352, and, the upper end portion 361 thereof protrudes though the hole 352. A
pressing portion 362 formed on the outer side-wall of the operation unit 360 touches
the upper side of the connecting portion 347 of the contact slip 340. The pressing
portion 362 is pressed upward by the elastic force of the contact slip 340 and touches
the lower side of the cover 350 as shown in Fig. 5.
[0007] In the state shown in Fig. 5, one movable contact portion 345 contacts to the long
fixed contact unit 330, but the other movable contact portion 346 does not contact
to neither of the contact units, accordingly the terminals 321 and 331 are not electrically
connected.
[0008] Hereinafter, the operation of the push switch having the above structure is described.
[0009] When the upper end portion 361 of the operation unit 360 is pressed downward, the
pressing portion 362 presses the connecting portion 347 of the contact slip 340 downward,
whereby the contact slip 340 rotates on the upward bent portion 341 supported by the
supporting portion 351 of the cover 350, whereby the bent portion 342 bends further,
also the movable contact portions 345 and 346 are elastically pressed and slide on
the inner side of the bottom of the case 310, whereby the movable contact portion
346 comes to contact to the short fixed contact unit 320 in the state that the other
movable contact portion 345 is in contact with the long fixed contact unit 330. As
a result, the terminals 321 and 331 are electrically connected through these contact
units. The operation unit 360 is pressed further downward until the lower end portion
363 of the operation unit 360 touches the inner side of the bottom of the case 310
as shown in Fig. 7 and stop the downward movement.
[0010] After that, when the force pressing the upper end portion 361 of the operation unit
360 is removed, the connecting portion 347 presses the pressing portion 362 of the
operation unit 360 upward with the elastic restoring force of the contact slip 340,
whereby the push switch comes back to the state as shown in fig. 5.
[0011] In the above, the stroke of the push switch is constituted with a pre-stroke comprising
the move of the operation unit 360 starting from the original state of Fig. 5 till
the state that the terminals 321 and 331 are electrically connected by the contact
between the movable contact portion 346 of the contact slip 340 and the short fixed
contact unit 320, and, an over-stroke comprising the move of the operation unit 360
starting from the state of the above pre-stroke till the state that the lower end
portion 363 of the operation unit 360 touches the inner side of the bottom of the
case 1. Therefore, the total stroke is considerably long.
[0012] However, in the above conventional push switch, the contact slip 340 is formed in
such a manner that an elastic thin metal plate is bent to have a shape like a character
of U having thin two leg portions 343 and 344. Therefore, careful attention have to
be paid in handling during transport and assembling for preventing the intertwining
and the deformation of the contact slip 340. Furthermore, the assembling of the switch
is difficult and inefficient because the assembling is performed in such a manner
that the contact slip 340 is set in the case 310 pressing the contact slip 340 with
the supporting portion 351 of the downward protrusion of the cover 350 and the pressing
portion 362 of the operation unit 360.
SUMMARY OF THE INVENTION
[0013] The present invention addresses the above problems in the conventional push switch,
and aims to provide a push switch in which the component parts are handled without
difficulty, and assembling productivity is superior, also operation stroke is long.
[0014] For realizing the above aim, the push switch of the present invention comprises:
(a) a switch substrate which has an outer fixed contact unit and a central fixed contact
unit, both of which are fixed to the switch substrate and the contact portions of
the respective fixed contact units are exposed from the upper side of the switch substrate,
also has respective contact terminals extended outward from the respective fixed contact
units,
(b) a movable contact unit which is formed with an elastic thin metal plate, and has
an outer annular portion placed on the outer fixed contact units, also has a tongue
shaped portion which faces toward the central fixed contact unit forming a predetermined
insulation gap between the tongue shaped portion and the central fixed contact unit,
(c) an elastic unit which is formed with an elastic material, and has a conical portion
having an opening at the lower side thereof, an upward protrusion and a downward protrusion
which protrudes downward from the upper end of the opening, and, presses the outer
annular portion of the movable contact unit with the lower end portion of the conical
portion,
(d) an operation unit which is disposed on the elastic unit in such a manner as to
be movable up and down, and, has a protrusion at the lower end periphery thereof for
preventing the slip off of the operation unit, and
(e) a cover which is fixed to the periphery of the switch substrate, and holds the
operation unit with the surrounding wall thereof in such a manner as to be movable
up and down without the upward slip off of the operation unit, also has a hole, through
which the operation unit protrudes, at the upper central portion thereof,
wherein, when the upper end portion of the operation unit is pressed, the conical
portion of the elastic unit elastically deforms first, whereby the downward protrusion
in the conical portion presses the tongue shaped portion of the movable contact unit,
whereby the tongue shaped portion touches the central fixed contact unit, next at
least one of the upward protrusion or the downward protrusion of the elastic unit
deforms, whereby the protrusion formed at the lower end periphery of the operation
unit touches the switch substrate. The above structure realizes a push switch in which
component parts are handled without difficulty, and the assembling productivity is
superior, also the operation stroke is long.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015]
Fig. 1 shows a cross sectional front view of a push switch in an exemplary embodiment
in the present invention,
Fig. 2 shows an exploded perspective view of the push switch in the exemplary embodiment
in the same,
Fig. 3A, Fig. 3B and Fig. 3C are cross sectional front views showing the states of
operations of the push switch in the exemplary embodiment in the same,
Fig. 4A, Fig. 4B and Fig. 4C are perspective views showing the shapes of cavities
and cuttings formed on the protrusions of the elastic unit of the push switch in the
exemplary embodiment in the same,
Fig. 5 shows a cross sectional front view of an example of conventional push switches,
Fig. 6 shows an exploded perspective view of the same, and
Fig. 7 is an cross sectional front view showing the state of an operation of the same.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Hereinafter, an exemplary embodiment in the present invention is described referring
to illustrations. Fig. 1 is a cross sectional front view showing a push switch in
an exemplary embodiment in the present invention, and Fig. 2 shows an exploded perspective
view of the push switch in the same.
[0017] In Fig. 1 and Fig. 2, on the upper side of a resinous plate shaped switch substrate
110, a shallow cavity 111 is formed. In the cavity 111, a central fixed contact unit
120 is disposed at the central position of the cavity 111, and two outer fixed contact
units 130 are disposed symmetrically about the central fixed contact unit 120 at the
positions outer than the central fixed contact unit 120. The contact units 120 and
130 are fixed to the substrate 110 by insert formation, and are exposed from the upper
side of the switch substrate 110, also have substantially same height. On outer sides
of the switch substrate 110, contact terminals 121 and 131 are disposed. One terminal
121 is electrically connected to the central fixed contact unit 120, and the other
terminal 131 is electrically connected to the outer fixed contact unit 130.
[0018] A movable contact unit 140 formed with an elastic thin metal plate has a shape shown
in Fig. 2. That is, the movable contact unit 140 comprises an outer annular portion
141, a tongue shaped portion 142 disposed at the central position of the outer annular
portion 141. The tongue shaped portion 142 bends upward at a connecting portion 143
which connects the tongue shaped portion 142 to the outer annular portion 141.
[0019] The outer annular portion 141 is placed on the outer fixed contact units 130. The
tongue shaped portion 142 is disposed in such a manner as to face toward the central
fixed contact unit 120 forming a predetermined insulation gap between the tongue shaped
portion 142 and the central fixed contact unit 120.
[0020] An elastic unit 150 formed with an elastic insulating material comprises a thin conical
portion 151 which has an opening at the lower side thereof, an upward protrusion 153
which is formed on the upper side of the conical portion 151 and has predetermined
dimensions, and a downward protrusion 156 which protrudes downward from the upper
end of the opening of the conical portion 151 and has predetermined dimensions. On
the upper end side 154 of the upward protrusion 153, a round cavity 155 having predetermined
dimensions is formed, and at the lower end side of the downward protrusion 156, a
round cavity 157 having predetermined dimensions is formed.
[0021] The diameters and the depth of the cavities 155 and 157 are determined in such a
manner that, when the elastic unit 150 is deformed by pressing downward the upper
end side 154 of the upward protrusion 153, the thin conical portion 151 bends backward
first, next the downward protrusion 156 compressibly deforms, last the upward protrusion
153 compressibly deforms.
[0022] The lower end portion 152 of the conical portion 151 of the elastic unit 150 is placed
on the outer annular portion 141 of the movable contact unit 140, and presses downward
the outer annular portion 141 onto the outer fixed contact units 130.
[0023] On the upward protrusion 153 of the elastic unit 150, a resinous operation unit 160
is disposed. The upward protrusion 153 engages with a cavity 161 formed at the lower
side of the operation unit 160. In this case, the flat surface of the upper end side
154 of the upward protrusion 153 touches the flat surface of the lower side of the
upper portion of the operation unit 160.
[0024] The operation unit 160 further comprises two protrusions 162 on the two different
positions of the outer side-wall thereof and a protrusion 163 which protrudes outward
from the lower end of the outer side-wall thereof.
[0025] On the inner side-wall of a resinous cover 170, two grooves corresponding to the
two protrusions 162 of the operation unit 160 are formed, and a surrounding wall 172
having a cavity corresponding to the protrusion 163 are formed, at the respective
corresponding positions. The two protrusions 162 of the operation unit 160 engage
with the two grooves of the cover 170, and the protrusion 163 of the operation unit
160 engages with the cavity of the surrounding wall 172 of the cover 170. By engaging
the outer side-wall of the operation unit 160 with the inner side-wall of the cover
170 as described in the above, the operation unit 160 is supported to be movable up
and down without the rotation and without the upward slip off of the operation unit
160.
[0026] The cover 170 is fixed to the switch substrate 110 by caulking after inserting protrusions
112 formed on the periphery of the upper side of the switch substrate 110 into the
cuttings 173 formed at the lower end periphery of the cover 170.
[0027] The assembling of the push switch in this exemplary embodiment having the above structure
is performed in such a manner that the component parts are placed on the switch substrate
110 in the order of the movable contact unit 140 first, next the elastic unit 150,
then the operation unit 160, last the cover 170 and these are fixed by the above caulking.
Therefore the assembling is simple and the respective component parts have shapes
which hardly deform, whereby the handling of the component parts is not difficult,
and automatic assembling can be realized without difficulty.
[0028] Hereinafter the operation of the push switch having the above structure is described.
[0029] Fig. 1 shows the state of switch-off. When the upper end side 164 of the operation
unit 160 is pressed downward, the operation unit 160 moves straight downward with
the guidance of a hole 171 of the cover 170 and the inner side of the surrounding
wall 172, whereby the flat lower side of the upper portion of the operation unit 160
presses downward the flat upper end side 154 of the upward protrusion 153 of the elastic
unit 150.
[0030] By the above operation, the thin conical portion 151 of the elastic unit 150 elastically
deforms and bends backward, whereby the lower end side of the downward protrusion
156 of the elastic unit 150 presses downward the tongue shaped portion 142 of the
movable contact unit 140, whereby the tongue shaped portion 142 contacts to the central
fixed contact unit 120 disposed on the switch substrate 110, whereby the central contact
unit 120 and the outer fixed contact units 130 (i.e., terminals 121 and 131) are electrically
connected and comes to the state of switch-on as shown in Fig. 3A.
[0031] The above operation constitutes a pre-stroke.
[0032] When the operation unit 160 is further pressed, the operation unit 160 further moves
downward, and the downward protrusion 156 elastically deforms as shown in Fig. 3B.
Last, the upward protrusion 153 of the elastic unit 150 deforms as shown in Fig. 3C,
and the operation unit 160 stops the downward movement when the protrusion 163 at
the lower end periphery of the operation unit 160 touches upper side of the switch
substrate 110.
[0033] The operation from the state of Fig. 3A to the state of Fig. 3C constitutes an over-stroke.
[0034] In the above pressing operation, the occurrence of slippage between the operation
unit 160 and the elastic unit 150 can be prevented because the upper portion of the
elastic unit 150 engages with the cavity 161 formed at the lower side of the operation
unit 160. Furthermore, the touching portions of both have flat surfaces, whereby the
elastic unit 150 is pushed substantially vertically downward and elastically deforms
without tilt.
[0035] After that, when the force pressing the operation unit 160 is removed, the elastic
unit 150 and the movable contact unit 140 come back to the state of Fig. 1 (i.e.,
state of switch-off) by the elastic restoring force of the elastic unit 150.
[0036] In the above description, round cavities 155 and 157 are respectively formed on the
upper end side 154 of the upward protrusion 153 and at the lower end side of the downward
protrusion 156 of the elastic unit 150 for setting the predetermined resilient force
and compressible dimension of the respective protrusions (153,156). However, the same
effect can be obtained by replacing each of the cavities 155 and 157 with a cross-shaped
cutting 181 which are symmetrical about the center thereof as shown in Fig. 4A, or
a round cavity having two-cutting 182 as shown in Fig. 4B, or a round cavity having
four-cutting 183 as shown in Fig. 4C.
[0037] Also, the same effect can be obtained by supporting the operation unit with the cover
to be movable up and down without rotation by shaping the outer side-wall of the operation
unit and either of the hole formed through the upper central portion of the cover
or the inner side of the surrounding wall into non-round.
[0038] In this exemplary embodiment, the following advantageous effects are obtainable.
(1) A push switch, in which the component parts thereof can be handled without difficulty,
and assembling productivity is superior, also an operation stroke comprising a pre-stroke
and an over-stroke is long, can be realized.
(2) In a push switch constituted in such a manner that, when the upper side of the
operation unit is pressed, the thin conical portion of the elastic unit elastically
deforms first, whereby the downward protrusion in the conical portion presses the
tongue shaped portion of the movable contact unit, whereby the tongue shaped portion
touches the central fixed contact unit, next the downward protrusion elastically deforms
by a predetermined dimension, last the upward protrusion elastically deforms, more
stable operation is realized in addition to the above effect.
(3) In a push switch constituted in such a manner that the setting of predetermined
resilient force and compressible dimension are set by forming the cavity having predetermined
size and depth or the cutting which is symmetrical about the center thereof having
predetermined size and depth on at least either of the upward protrusion or the downward
protrusion of the elastic unit, the setting of the resilient force in the over-stroke
and the length of the over-stroke can be set at desired values without difficulty.
(4) In a push switch constituted in such a manner that, the flat upper end side of
the upward protrusion of the elastic unit touches the flat lower side of the operation
unit, and the protrusion formed on one side engages with the cavity formed on the
other side, the positioning between the lower side of the operation unit and the upper
end side of the upward protrusion of the elastic unit becomes stable and the slippage
between both in the occasion of the pressing operation of the operation unit can be
prevented, whereby the elastic unit can surely be elastically deformed.
(5) In a push switch constituted in such a manner that the outer side-wall of the
operation unit and either of the hole formed through the upper central portion of
the cover or the inner side of the surrounding wall are shaped into non-round, and
the operation unit is supported by the cover to be movable up and down without rotation,
the operation unit is guided to maintain a constant facing direction without rotation
during up and down movement, whereby the elastic unit can be elastically deformed
without tilt, which enables surer switching operation.
(6) In a push switch constituted in such a manner that the outer fixed contact units
and the inner fixed contact unit are exposed from the upper side of the switch substrate
and have substantially same height, and the tongue shaped portion disposed at the
central position of the movable contact unit is bent upward at the connecting portion,
which connects the tongue shaped portion to the outer annular portion, for forming
a predetermined insulation gap between the tongue shaped portion and the central fixed
contact unit, the insulation gap between the central fixed contact unit and the tongue
shaped portion can be surely maintained, also the movable contact unit hardly deforms
as a whole even when the tongue shaped portion of the movable contact unit is strongly
pressed because the movable contact unit becomes only flat even under strong pressing
force, whereby the electric characteristic of the push switch becomes stable.
1. A push switch comprising:
(a) a switch substrate (110) having an outer fixed contact unit (130) and a central
fixed contact unit (120), wherein both contact units (130,120) are fixed to said substrate
(110), and have respective contact portions exposed from the upper side of said switch
substrate (110), also have connecting terminals (121,131) extended outward from said
respective fixed contact units (130,120);
(b) a movable contact unit (140) formed with an elastic thin metal plate, wherein
said movable contact unit (140) has an outer portion (141) placed on said outer fixed
contact unit (130), and a tongue shaped portion (142) which faces toward said central
fixed contact unit (120) forming a predetermined insulation gap between said tongue
shaped portion (142) and said central fixed contact unit (120).
(c) an elastic unit (150) formed with an elastic material, wherein said elastic unit
(150) has a conical portion (151) having an opening at the lower side thereof, an
upward protrusion (153) and a downward protrusion (156) which protrudes downward from
the upper end of said opening, and, presses said outer portion (141) of said movable
contact unit (140) with the lower end portion (152) of said conical portion (151);
(d) an operation unit (160) disposed on said elastic unit (150) in such a manner as
to be movable up and down, wherein said operation unit (160) has a protrusion (163)
at the lower end periphery of said operation unit (160) for preventing the slip off
of said operation unit (160);
(e) a cover (170) fixed to the periphery of said switch substrate (110), wherein said
cover (170) holds said operation unit (160) with a surrounding wall (172) thereof
in such a manner as to be movable up and down without the upward slip off of the operation
unit (160), and has a hole (171), through which the operation unit (160) protrudes,
at the upper central portion thereof;
wherein, when said upper end portion (164) of said operation unit (160) is pressed,
said conical portion (151) of said elastic unit (150) elastically deforms first, whereby
said downward protrusion (156) in said conical portion (151) presses said tongue shaped
portion (142) of said movable contact unit (140), whereby said tongue shaped portion
(142) contacts to said central fixed contact unit (120), next at least one of said
upward protrusion (153) and said downward protrusion (156) elastically deforms, whereby
said protrusion (163) at the lower end periphery of said operation unit (160) touches
said switch substrate (110).
2. The push switch of claim 1, wherein, when said upper end portion (164) of said operation
unit (160) is pressed, said conical portion (151) of said elastic unit (150) elastically
deforms first, whereby said downward protrusion (156) in said conical portion (151)
presses said tongue shaped portion (142) of said movable contact unit (140), whereby
said tongue shaped portion (142) contacts to said central fixed contact unit (120),
next said downward protrusion (156) elastically deforms by a predetermined dimension,
last said upward protrusion (153) elastically deforms.
3. The push switch of claim 1 or 2, wherein the resilient force and compressible dimension
of said elastic unit (150) is set at respective predetermined values by forming one
of a cavity having predetermined size and depth, and, a cutting which is symmetrical
about the center thereof and has predetermined size and depth, on at least one of
said upward protrusion (153) and said downward protrusion (156) of said elastic unit
(150).
4. The push switch of claim 1 or 2, wherein the flat surface of said upper end side (154)
of said upward protrusion (153) touches the flat surface of the lower side of said
operation unit (160), and, a protrusion formed on one side engages with a cavity formed
on the other side.
5. The push switch of claim 3, wherein the flat surface of said upper end side (154)
of said upward protrusion (153) touches the flat surface of the lower side of said
operation unit (160), and, a protrusion formed on one side engages with a cavity formed
on the other side.
6. The push switch of claim 1 or 2, wherein the outer side-wall of said operation unit
(160) and one of said hole (171) formed through upper central portion of said cover
(170) and inner side of said surrounding wall (172) are shaped into non-round, whereby
said operation unit (160) is held by said cover (170) in such a manner as to be movable
up and down without rotation.
7. The push switch of claim 3, wherein the outer side-wall of said operation unit (160)
and one of said hole (171) formed through upper central portion of said cover (170)
and inner side of said surrounding wall (172) are shaped into non-round, whereby said
operation unit (160) is held by said cover (170) in such a manner as to be movable
up and down without rotation.
8. The push switch of claim 4, wherein the outer side-wall of said operation unit (160)
and one of said hole (171) formed through upper central portion of said cover (170)
and inner side of said surrounding wall (172) are shaped into non-round, whereby said
operation unit (160) is held by said cover (170) in such a manner as to be movable
up and down without rotation.
9. The push switch of claim 5, wherein the outer side-wall of said operation unit (160)
and one of said hole (171) formed through upper central portion of said cover (170)
and inner side of said surrounding wall (172) are shaped into non-round, whereby said
operation unit (160) is held by said cover (170) in such a manner as to be movable
up and down without rotation.
10. The push switch of to claim 1 or 2, wherein said outer fixed contact unit (130) and
said central contact unit (120), both of which are exposed from the upper side of
said switch substrate (110), have substantially same height, and, said tongue shaped
portion (142) disposed at the central position of said movable contact unit (140)
is bent upward at said connecting portion (143), which connects said tongue shaped
portion (142) to said outer portion (141), for forming a predetermined insulation
gap between said tongue shaped portion (142) and said central fixed contact unit (120).
11. The push switch of claim 3, wherein said outer fixed contact unit (130) and said central
contact unit (120), both of which are exposed from the upper side of said switch substrate
(110), have substantially same height, and, said tongue shaped portion (142) disposed
at the central position of said movable contact unit (140) is bent upward at said
connecting portion (143), which connects said tongue shaped portion (142) to said
outer portion (141), for forming a predetermined insulation gap between said tongue
shaped portion (142) and said central fixed contact unit (120).
12. The push switch of claim 4, wherein said outer fixed contact unit (130) and said central
contact unit (120), both of which are exposed from the upper side of said switch substrate
(110), have substantially same height, and, said tongue shaped portion (142) disposed
at the central position of said movable contact unit (140) is bent upward at said
connecting portion (143), which connects said tongue shaped portion (142) to said
outer portion (141), for forming a predetermined insulation gap between said tongue
shaped portion (142) and said central fixed contact unit (120).
13. The push switch of claim 5, wherein said outer fixed contact unit (130) and said central
contact unit (120), both of which are exposed from the upper side of said switch substrate
(110), have substantially same height, and, said tongue shaped portion (142) disposed
at the central position of said movable contact unit (140) is bent upward at said
connecting portion (143), which connects said tongue shaped portion (142) to said
outer portion (141), for forming a predetermined insulation gap between said tongue
shaped portion (142) and said central fixed contact unit (120).