Push switch

FIELD OF THE INVENTION

The present invention relates to a small push switch used in various electronic appliances.

BACKGROUND OF THE INVENTION

In the recent trend of smaller size and higher quality for electronic appliances, push switches and other electronic components are desired to be small, thin, and to generate clear handling feeling. A push switch having a longer operation stroke is demanded.

A configuration of a conventional push switch disclosed in Japanese Laid-open Patent No.3-214519 will be explained, referring to FIG.

14

and FIG.

15

.

FIG. 14

is a front sectional view of a conventional push switch

5

. In the bottom of a switch case

1

of molded resin box, two outside fixed contacts

2

coupled to a connection terminal

2

A and a central fixed contact

3

coupled to a connection terminal

3

A are fixed by insert molding. A movable contact

4

of elastic thin metal is disposed on the two outside fixed contact points

2

.

The movable contact point

4

is made of elastic thin metal plate, and includes a ring-shaped periphery

4

C and a tongue

4

A extending from the periphery

4

C toward its center. The tongue

4

A is folded in an upward slope at a junction

4

B with the periphery

4

C. The periphery

4

C of the movable contact

4

is disposed on the outside fixed contacts

2

to contact with the contacts

2

electrically. The tongue

4

A in the center faces the central fixed contact

3

in this arrangement, providing a switch contact.

An elastic element

6

is made of rubber or other elastic material, and has a columnar bar section

6

B at its upper part, and a thin conical section

6

D at its lower part. A drooping section

6

C projecting downward from a inside central part of the conical section

6

D faces the tongue

4

A of the movable contact

4

at a certain gap. An outer lower end

6

A of the conical section

6

D is disposed on the top of the periphery

4

C of the movable contact

4

.

An operation element

7

is disposed on the bar section

6

B. The periphery of a lower part

7

A of the operation element

7

is regulated by the inner periphery of a wall

1

A of the switch case

1

, thus allowing the operation element

7

to move up and down without inclination.

Two protrusions

7

B on the periphery are engaged with upper and lower grooves

1

B provided in the inner periphery of the wall

1

A of the switch case

1

, respectively. The operation element

7

is locked so as not to rotate or slip out upward. A protrusion

7

C projecting upward from the switch case

1

is an operation part.

An operation of the push switch

5

will be explained below.

The protrusion

7

C of the operation element

7

is pushed during the switch being turned off as shown in

FIG. 14

, and then, the operation element

7

pushes the elastic element

6

in the switch case

1

. This operation deforms the conical section

6

D of the elastic element

6

, and generates a clear click feel at the time of the deformation. Simultaneously, the drooping section

6

C of the elastic element

6

pushes down the tongue

4

A into the center of the movable contact

4

, and the lower side of the tongue

4

A contacts with the central fixed contact

3

. And the outside fixed contacts

2

and the central fixed contact point

3

, that is, the two connection terminals

2

A and

3

A then conduct with each other.

Then, when a pushing force to the operation element

7

is removed, the elastic element

6

and movable contact

4

return to an initial state with their own elastic restoring force, and the two connection terminals

2

A and

3

A opens again.

The push switch

5

installed in an electronic appliance will be explained.

FIG. 15

is a front view of a conventional push switch installed in an electronic appliance. The push switch

5

is disposed on a wiring board

8

with the connection terminals

2

A and

3

A connected electrically at the lower side by, e.g. soldering, and is placed immediately beneath an operation button

9

fitted to a case

10

of the appliance corresponding to the position of the operation element

7

.

The interval between the lower side of the operation button

9

and the upper side of the wiring board

8

is determined according to the height of the push switch

5

.

In the conventional push switch

5

, however, due to fluctuations of components and their combination in the electronic appliance including the switch, or to an installing state of the push switch

5

, it is difficult to set the interval between the lower side of the operation button

9

and the upper side of the wiring board

8

to be the height of the push switch

5

. If the interval is too wide, a gap between the operation button

9

and the upper side of the push switch

5

makes the operation button

9

loose. If the interval is too narrow, on the other hand, the operation button slightly pushes the operation element

7

of the push switch

5

, and this makes the sensation of manipulation of the push switch

5

dull.

SUMMARY OF THE INVENTION

The push switch can absorb fluctuations of components and their combination of an electronic appliance, and is prevented from looseness in an operation button of the electronic appliance including the switch, thus maintaining a clear manipulation feeling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a front sectional view of a push switch according to a first exemplary embodiment of the present invention.

FIG. 2

is a perspective exploded view of the push switch according to the first embodiment.

FIG. 3

is a front sectional view of the push switch according to the first embodiment.

FIG. 4

is a front sectional view of the push switch according to the first embodiment.

FIG. 5

is a diagram showing the relation between an operating distance and an operating force for the push switch according to the first embodiment.

FIG. 6

is a sectional view of the push switch installed in an electronic appliance according to the first embodiment.

FIG. 7A

to

FIG. 7J

are partial outline perspective views of another push switch according to the first embodiment.

FIG. 8

is a front sectional view of a push switch according to a second exemplary embodiment of the invention.

FIG. 9

is a perspective exploded view of the push switch according to the second embodiment.

FIG. 10

is a front sectional view of the push switch according to the second embodiment.

FIG. 11

is a front sectional view of the push switch according to the second embodiment.

FIG. 12

is a front sectional view of another push switch according to the second embodiment.

FIG. 13

is a front sectional view of the push switch installed in an electronic appliance according to the second embodiment.

FIG. 14

is a front sectional view of a conventional push switch.

FIG. 15

is a front view of the conventional push switch installed in an electronic appliance.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(Exemplary Embodiment 1)

FIG. 1

is a front sectional view of a push switch according to a first exemplary embodiment of the present invention, and

FIG. 2

is an exploded perspective view of the switch.

In an inner bottom

11

B of a resin-made switch case

11

of a box shape, a central fixed contact

12

and two outside fixed contacts

13

are disposed at symmetrical positions thereof being fixed by insert molding. The contacts are exposed nearly at the same heights. Connection terminals

12

A and

13

A communicating with the fixed contacts

12

and

13

, respectively, are drawn out of a side wall of the case. A columnar crimping protrusion

11

A is provided on an upper side of the switch case

11

. A movable contact

14

made of elastic thin metal plate includes a periphery

14

A of a circular ring shape, a tongue

14

B provided in the center of the contact, and a linkage

14

C linking the periphery

14

A and the tongue

14

B. The tongue

14

B is folded with an upward inclination at the linkage

14

C. In the movable contact

14

, the periphery

14

A is mounted on the outside fixed contact

13

on the switch case

11

. The tongue

14

B faces the central fixed contact

12

at a certain interval.

An elastic element

15

made of elastic insulating material includes an upward bar section

15

C and a conical section of a thin wall opening downward both being formed integrally in its lower part. A straight groove is provided in the center of the upper side of the bar section

15

C, and the other portion functions as a first deforming section

15

E. The conical section disposed in the lower part of the bar section

15

C functions as a second deforming section

15

A. The conical section as the second deforming section

15

A includes a drooping section

15

D projecting downward in its inside.

The elastic element

15

has its lower end portion

15

B of conical section disposed on the periphery

14

A of the movable contact

14

, and the movable contact

14

electrically conducts with the outside fixed contact

13

at its downward side.

When the first deforming section

15

E pushes the elastic element

15

down to deform, the first deforming section

15

E deforms by compressing elastically, and then, the second deforming section

15

A, i.e., a conical section of a thin wall buckles and deforms. That is, the width and depth of the groove are determined, so that a force for deforming the first deforming section

15

E may be smaller than a force for deforming the second deforming section

15

A.

A cover

16

has a box shape opening downward, and has a central hole

16

A in the center of its upper side. A crimping bump

11

A on the upper side of the switch case

11

is inserted in a crimping hole

16

B formed in a downward flange surface, and the upper part of crimping bump

11

A is crushed to be crimped, and is fixed to the switch case

11

.

While the cover

16

is fixed, the bar section

15

C of the elastic element

15

projects upward from the central hole

16

A, and the upper side of the lower end portion

15

B of the elastic element

15

is pushed to contact elastically with the periphery

14

A of the movable contact

14

at the lower end side of the cover

16

. An elastic force maintains a stable electrical conduction of the lower side of the periphery

14

A and the outside fixed contact

13

. The elastic force holds the elastic element

15

so as not to rotate or slip out upward.

An operation of the push switch will be explained.

In case that the switch is turned off, as shown in

FIG. 1

, when the elastic element

15

is pushed down, only the first deforming section

15

E of the upper part of the elastic element

15

deforms elastically as shown in FIG.

3

. The deformation corresponds to a first deforming stage in

FIG. 5

, which shows the relation between an operating distance and an operating force. After the first deforming section

15

E deforms, when a further pressing force is applied, the second deforming section

15

A of thin wall conical section of the elastic element

15

buckles to deform, thereby creating a click feel.

The lower end side of the drooping section

15

D at the inside of the second deforming section

15

A pushes the tongue

14

B of the movable contact point

14

down to have the tongue

14

B contact with the central fixed contact

12

on the bottom of the switch case

11

. As a result, the central fixed contact

12

and outside fixed contacts

13

, that is, the connection terminals

12

A and

13

A conduct with each other, and the switch is turned on, as shown in FIG.

4

. The stroke from the beginning of deformation of the second deforming section

15

A in the thin wall conical section until the switch is turned on corresponds to the second deforming stage shown in FIG.

5

.

When the pressing force on the elastic element

15

is removed, the elastic element

15

and movable contact

14

return to the initial state shown in

FIG. 1

by their own elastic restoring force, and the switch is turned off.

FIG. 6

is a sectional view of the push switch according to the embodiment installed in an electronic appliance. Being turned off, the push switch is disposed, so that the elastic element

15

may be positioned immediately beneath an operation button

19

provided in a case

18

of the electronic appliance.

A switch mounting interval between the upper side of the wiring board

17

on which the push switch is installed and the lower side of the operation button

19

varies according to dimension or combination state of the components of the electronic appliance. In this embodiment, the switch mounting interval is slightly smaller than the height of the push switch. Therefore, the push switch is installed so that the first deforming section

15

E in the upper part of the elastic element

15

abuts on the lower side of the operation button

19

, being deforming. This dimensional arrangement absorbs fluctuation of the switch mounting interval with the first deforming section

15

E provided in the upper side of the bar section

15

C of the elastic element

15

, thus eliminating looseness of the operation button

19

of the electronic appliance.

If the switch mounting interval is smaller than the maximum deforming dimension of the first deforming section

15

E of the elastic element

15

, the second deforming section

15

A of the conical section of the elastic element

15

does not deform. This prevents the handling feeling of the push switch from being influenced due to excessive pushing of the elastic element

15

.

Thus, according to the embodiment, fluctuation due to components of the electronic appliance and their combination can be absorbed, looseness of the operation button

19

does not occur, and a push switch maintaining a favorable operation feeling is obtained.

It is important to set the switch mounting interval properly in consideration of the mounting of the push switch in relation to the wiring board

17

.

In the foregoing explanation, the first deforming section

15

E of the push switch is the bar section

15

C having a straight groove in the elastic element

15

, but it may be formed as shown in

FIG. 7A

to FIG.

7

J.

FIG. 7A

shows a straight convex shape

15

d

.

FIG. 7B

shows a straight convex shape

15

d

having a circular convex part

15

e

at its center.

FIG. 7C

shows a concave shape

15

f

, a shape reverse to that shown in FIG.

7

B.

FIG. 7D

shows a ring-shaped protruding shape

15

g

.

FIG. 7E

shows a circular convex part

15

h

only at its center.

FIG. 7F

shows a cross-shaped convex shape

15

i

symmetrical about its center.

FIG. 7G

shows a cross concave shape

15

j

reverse to that shown in FIG.

7

F.

FIG. 7H

shows a convex shape

15

k

having cross shape and circular shape.

FIG. 71

shows a concave shape

151

reverse to that shown in FIG.

7

H.

FIG. 7J

shows a concentric pointed shape

15

m

in which the bar section becoming smaller in diameter toward its upper side.

These shapes may be combined, and the configuration is not particularly defined as far as the first deforming section maintains a specified deforming amount and deforms elastically with a force smaller than a force for deforming the second deforming section.

(Exemplary Embodiment 2)

FIG. 8

is a front sectional view of a push switch accorfing to a second exemplary embodiment of the invention, and

FIG. 9

is an exploded perspective view of the switch. In an inner bottom of a central concave portion of a square switch case

21

made of insulating resin, a central fixed contact

22

and two outside fixed contacts

23

is disposed at symmetrical positions, being fixed by insert molding while exposing nearly at the same height. Connection terminals

22

A,

23

A communicating with the fixed contacts

22

and

23

, respectively, are drawn out outward of a side wall of the case, and a columnar crimping bump

21

A is provided at the upper side corner.

In a movable contact

24

, similarly to the contact point

14

of embodiment 1, a periphery

24

A of a circular ring shape is disposed on the outside fixed contact

23

of the switch case

21

, and a tongue

24

B folded upward at a linkage

24

C in this state and disposed in the center of the outer periphery

24

A. The tongue

24

B faces the central fixed contact

22

at a certain interval.

An elastic element

25

made of insulating elastic material includes an upper conical section

25

C and a thin wall conical section opening downward formed integrally in its lower part. The elastic element

25

has a step

25

F in the middle position of the bar section

25

C. From the step

25

F, its upper part has a circular convex shape having a slightly smaller diameter than the bar section

25

C.

The circular convex portion functions as a first deforming section

25

E, and the conical section in the lower part of the bar section

25

C functions as a second deforming section

25

A. When the elastic element

25

is pushed down and deformed, the first deforming section

25

E in the upper part of the bar section

25

C is elastically compressed and deformed, and then the second deforming section

25

A of thin wall conical section buckles to deform. That is, the diameter and height of the circular convex portion are defined so that a force for deforming the first deforming section

25

E may be smaller than a force for deforming the second deforming section

25

A.

Similarly to embodiment 1, the elastic element

25

has a drooping section

25

D in the inside of the conical section, and the lower end portion

25

B of the conical section is disposed on the periphery

24

A of the movable contact

24

. In this configuration, the drooping section

25

D faces the tongue

24

B of the movable contact

24

at a certain interval.

An operation element

26

is a resin-made box opening downward having a central hole

26

C in the center of its upper side. The operation element

26

has two engaging portions

26

D each having a convex shape in a vertical direction at a specified width outward of a side wall

26

B and stopping pawls

26

A for preventing the element from slipping out. The pawls are provided at the lower end of the side wall

26

B of positions orthogonal to the engaging portions

26

D at symmetrical positions about the center of the central hole

26

C.

The operation element

26

is disposed on the elastic element

25

, having the first deforming section

25

E of the elastic element

25

project upward through the central hole

26

C in the center of its upper side. The peripheral lower side

26

E of the central hole

26

C pushes the step

25

F of the bar section

25

C of the elastic element

25

.

The size of the central hole

26

C of the operation element

26

is defined, so that the first deforming section

25

E of the elastic element

25

may not contact with the inner peripheral wall of the central hole

26

C even if being elastically compressed to be positioned flush with the upper side of the operation element

26

.

In a tubular resin-made linkage

27

, the upper part of the operation element

26

projects upward through a center hole

27

A. A lower crimping notch

27

B of the linkage

27

is crimped and fixed to the crimping protrusion

21

A at the upper side corner of the switch case

21

, and is fitted to the switch case

21

.

The linkage

27

has, at its inner wall, a groove

27

C penetrating in the vertical direction corresponding to the engaging portion

26

D of convex shape provided in the side wall

26

B of the operation element

26

. The engaging portion

26

D is engaged with the groove

27

C without looseness, thus allowing the operation element

26

to be smoothly guided vertically. In an ordinary state in which a pushing force is not applied as shown in

FIG. 8

, the stopping pawl

26

A of the operation element

26

stops at the lower side around the center hole

27

A, and this prevents the operation element

26

from slipping out.

An engaging area between the groove

27

C and engaging portion

26

D is not illustrated in the sectional view in FIG.

8

.

In the side wall downward from the stopping pawl

26

A of the linkage

27

, a recess

27

D is formed toward radially. When moving downward of the operation element

26

, the stopping pawl

26

A can move along recess

27

D without obstacle. At the side of the recess

27

D, the stopping pawl

26

A moves while having its side guided. That is, the engaging portions

26

D and stopping pawl

26

A of the operation element

26

are regulated in their movement in the vertical direction by the groove

27

C and recess

27

D, and prevents the operation element

26

from rotation and upward slip-out.

An operation of the push switch according to this embodiment will be explained.

In an ordinary state in which a pushing force is not applied as shown in

FIG. 8

, the first deforming section

25

E of the elastic element

25

projecting through the upper side of the operation element

26

is pushed by a pushing force applied through an operation button (not shown) of an electronic appliance. The button is slightly larger than the central hole

26

C of the operation element

26

. As a result, as shown in

FIG. 10

, the first deforming section

25

E is compressed and deforms elastically until the push button abuts on the upper side of the operation element

26

. The deforming at this moment corresponds to the first deforming stage in FIG.

5

.

Upon being further pushed down, the operation element

26

is pushed by the operation button, and the operation element

26

straightly moves down while the engaging portions

26

D and stopping pawl

26

A are guided by the groove

27

C and side of the recess

27

D. Simultaneously, the peripheral lower side

26

E of the central hole

26

C applies a downward pushing force to the step

25

F of the bar section

25

C of the elastic element

25

.

When the pushing force to the step

25

F exceeds a predetermined value, the second deforming section

25

A in the thin wall conical section of the elastic element

25

buckles to deform, and generates a click feel. Simultaneously, the lower end side of the drooping section

25

D in the inside pushes the tongue

24

B of the movable contact point

24

down to have the tongue contact with the central fixed contact

22

on the switch case

21

. Then, the central fixed contact

22

and outside fixed contacts

23

, that is, the connection terminals

22

A and

23

A conduct with each other, thus having the switch turned on, as shown in FIG.

11

.

In this explanation, the stroke from beginning of the deformation of the second deforming section

25

A until the switch is turned on corresponds to the second deforming stage in FIG.

5

.

When the switch according to this embodiment is mounted, similarly to embodiment 1, in consideration of fluctuations of dimensions and combination of components of the electronic appliance, only the first deforming section

25

E of the elastic element

25

deforms slightly. This arrangement has the operation button of the electronic appliance positioned at a predetermined clearance against the operation element

26

. This eliminates looseness of the operation button.

Since the first deforming section

25

E is deformed by a smaller force than the second deforming section

25

A of the conical section of the elastic element

25

, the push switch can be installed while having a desired operation feeling.

Thus, the switch of the embodiment, similarly to embodiment 1, can be installed while absorbing fluctuations of components of the electronic appliance and their combination, is prevented from looseness of operation button, and generates a favorable operation feeling.

If the operation button of the electronic appliance has a hinge shape and is pressed obliquely in the switch of the embodiment, the operation element

26

is guided by the linkage

27

, and can be moved up and down smoothly. Therefore, the switch generates a favorable feeling stably at its manipulation.

According to the embodiment, the first deforming section

25

E of the elastic element

25

projects upward through the central hole

26

C of the operation element

26

. However, as shown in a sectional view of another switch in

FIG. 12

, the upper side of an elastic element

28

may be covered with an operation element

29

. This switch can be installed, while having only a first deforming section

28

A deform slightly. At this moment, a silencing measure may preferably be employed for its manipulation.

The push switch of the embodiment can be used in a operation unit for telephoto imaging operation or wide-angle imaging operation at a zoom operation unit of a video camera, as shown in a front view of the switch installed in an electronic appliance shown in FIG.

13

.

In this case, two push-ON switch are arranged and soldered on a wiring board

30

, and an operation button

31

of seesaw action for pushing the push switches is provided thereon in a case

32

of the electronic appliance.

In this case, when changing over from telephoto imaging operation to wide-angle imaging operation, or from wide-angle imaging operation to telephoto imaging operation, the lower side of the operation button

31

collides against an operation plane of the push switch. This generates a colliding noise, which is recorded together with an image. In the push switch of the embodiment shown in

FIG. 8

, the first deforming section

25

E in the upper part of the elastic element

25

projects to the upper part of the operation element

26

. Therefore, the lower side of the operation button

31

collides against the first deforming section

25

E of the elastic element

25

, so that the first deforming section

25

E functions as a shock absorber. This prevents the colliding noise from being generated. Even if the operation button

31

is pushed obliquely to press the push buttons, the switch of the embodiment assures a smooth and favorable operation since the operation element

26

moves up and down smoothly.

Thus, the push switch of the embodiment does not require a cushion member adhered to the upper or lower side of the operation button, the colliding noise can be eliminated easily, and its operation efficiency is excellent.