Push-on switch, electronic apparatus using the same and method for mounting the switch

FIELD OF THE INVENTION

The present invention relates to a side-push type push-on switch for use in operating sections of various kinds of electronic apparatus. A method for mounting the switch is also included.

BACKGROUND OF THE INVENTION

There is an increasing need for inexpensive push-on switches that can be operated with a sidewise push force, or an operating force exerted in a direction parallel to the surface plane of a printed circuit board. Also, in view of the prevailing trends for downsized equipment and the preference for slim-shaped designs in the market of electronic apparatus, switches for such apparatus are requested to be small enough to satisfy various designing requirements.

A side-push type push-on switch known to meet the above-described general requirements is disclosed in Japanese Utility Model Laid-open Publication No. 51126.

FIG. 15

shows a cross-sectional side view of a conventional push-on switch, and

FIG. 16

is an exploded perspective view. As shown in

FIG. 16

, a resin case

1

that opens upward is provided in its inner recess with a pair of outer fixed contact points

2

and a central fixed contact point

3

formed integrally by insert molding. The respective fixed contact points

2

and

3

are electrically coupled with terminals

4

provided on an outside wall surface of the resin case

1

.

A rectangular movable contact

5

made of an elastic thin metal sheet is formed of a frame

5

A and a bridging arch

5

B disposed in the middle of the frame

5

A. The movable contact

5

is placed so that the frame

5

A makes contact with the outer fixed contact points

2

.

The bridging arch

5

B of movable contact

5

is held above the central fixed contact point

3

with a certain specific clearance.

Placed further above are a flexible anti-dust sheet

6

made of an insulating resin and an operating member

7

.

The operating member

7

consists of an operating section

8

protruding toward the front from an opening

1

A of side wall of case

1

, and a flat plate section

9

formed integrally behind the operating section

8

. The flat plate section

9

is provided in the middle part with a C-shaped vacancy

10

(“C-shaped” includes a square shape without one side), with its opening facing the front; the remaining central portion has a thinned area

12

at a stem region so that the central portion functions as a pushing section

11

, which pushes the contacts.

The operating member

7

is placed, at the flat plate section

9

, on a step existing around the recess of case

1

so that the pushing section

11

is located above the bridging arch

5

B of movable contact

5

.

A press board

13

is attached on the case

1

covering the flat plate section

9

of operating member

7

, with claws

13

A hooked to recesses

1

B provided on the outer wall.

Thus the flat plate section

9

is supported between the step existing around the recess of case

1

and the bottom surface of the press board

13

, and the operating member

7

can slide to-and-fro.

In the press board

13

, an “L”-shaped bracket

15

is formed downward between a pair of slits

14

. The steep-angled front face of bracket

15

contacts with the tip end

11

A of the pushing section

11

of the operating member

7

.

The above-configured conventional push-on switch is, in a normal mounting method, put on a printed circuit board and soldered, at its external connection terminals

4

, with a circuit pattern (not shown) formed on the printed circuit board (not shown) of an apparatus, with the operating section

8

protruded from the front edge.

As to the operating mechanism of the conventional push-on switch, when the operating section

8

of operating member

7

protruding from the front edge of the printed circuit board is pressed towards a direction as indicated by an arrow in

FIG. 15

, the flat plate section

9

, which is an integral part of the operating section

8

, moves together along a space formed by parallel surfaces of the case

1

and the press board

13

. The pushing section

11

moves in the same direction as well.

Since the pushing section

11

is in contact, at the tip end

11

A, with the steep-angled front face of the bracket

15

of press board

13

, the whole pushing section

11

bends downward with the thinned area

12

formed at the stem as the fulcrum. The bottom surface of tip end

11

A of pushing section

11

pushes the bridging arch

5

B of movable contact

5

down via the anti-dust sheet

6

, and then the bridging arch

5

B is reversed to mechanically contact, at its bottom surface, with the central fixed contact point

3

. The outer fixed contact points

2

and the central fixed contact point

3

are made to have an electrical contact via the movable contact

5

; or, the switch is brought to ON state.

When the pressure on the operating section

8

is withdrawn, the pushing section

11

is pushed back to its upper position by an elastic restorative force of the bridging arch

5

B of movable contact

5

, and slides along the bracket

15

to return to the original position; thus, the switch returns to the OFF state as shown in FIG.

15

.

In the above-configured conventional push-on switch, the pushing section

11

needs to be provided in the operating member

7

; therefore, a C-shaped vacancy

10

has to be formed in the flat plate section

9

and a thinned area

12

must be created at the stem. In order to meet the stricter requirements for downsizing, it is desired for the length of the pushing section

11

of operating member

7

to be shorter, the thickness of the thinned area

12

is to be reduced a step further, and also the size of the movable contact

5

is to be still smaller. This means that it is necessary to make more precise machining for the dies and molds, and to provide more severe controls over, for example, the flow characteristics of resin materials, the conditions for operating the molding machines, as well as the maintenance of precision dies and molds and other items. This inevitably results in a higher cost.

Conventionally, the mounted switches are fixed only by soldering the terminals

4

on a printed circuit board. Therefore, the conventional switches are vulnerable to operating forces exerted in parallel with the printed circuit board. Enhancement of the mounting strength has been an outstanding item that needs improvement with the conventional push-on switches.

The present invention addresses the above tasks for improvement, and aims to provide a compact side-push type push-on switch. Die and mold machining and preparation of constituent parts for the push-on switch of the present invention are easier and lower in total cost. In the push-on switches of the present invention, operating forces exerted onto the switch are encountered by the end-face at the edge of a printed circuit board.

SUMMARY OF THE INVENTION

A switch of the present invention comprises:

an insulating resin case containing a main body of a switch mechanism formed in a front-open cavity, where a central fixed contact point and an outer fixed contact point are fixed on the inner surface of a recess;

a domed movable contact housed in the recess, the movable contact constituting the switching contact element coupled with the fixed contact points; and

an operating body supported by a cover so that it can move to-and-fro for pushing at the rear end the domed movable contact.

The resin case is provided with an overhang which stretches (extends) horizontally from the case in the upper part of a region corresponding to the main body of the switch mechanism for a distance greater than the size of main body region. The overhang is provided with terminals, electrically coupled with the central fixed contact point and the outer fixed contact point, respectively.

Thus, a complex mechanism conventionally needed for converting a sidewise operating force into a switching action is replaced by a simple structure. Namely, in a side-push type push-on switch of the present invention, the domed movable contact is pushed directly by the rear end of an operating body which can move to-and-fro in the direction of the operating force.

The constituent components of the above-configured push-on switch are of simple construction, so they can be prepared through simple and easy procedures of mold machining and/or other manufacturing processes at low cost. In addition, the push-on switch operates with a superior functional feeling.

Furthermore, the push-on switch of the present invention is mounted on a printed circuit board with the back wall of the case, in the main body region, making contact with the end-face of a cut provided in a printed circuit board while a bottom of the overhang is immediately contact on to the upper surface of the printed circuit board, and the terminals provided in the overhang are connected with respective circuit patterns on the printed circuit board. Therefore, the operating force applied to the operating body is ultimately encountered by the end-face of the printed circuit board in an area behind the main body. Thus high connection reliability is ensured in the present push-on switches with respect to the printed circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a cross-sectional view of a push-on switch in a first exemplary embodiment of the present invention.

FIG. 2

is a perspective view of the push-on switch, as a finished product.

FIG. 3

is an exploded perspective view of the push-on switch.

FIG. 4

is a cross-sectional view of the push-on switch, in a state of being pushed.

FIG. 5A

is a perspective view showing a method for mounting the push-on switch.

FIG. 5B

is a perspective view showing another method for mounting the push-on switch.

FIG. 6

is a perspective view in part of an electronic apparatus, showing a state where the push-on switch is mounted on a printed circuit board.

FIG. 7A

is a cross-sectional view showing a state where the push-on switch is put on a printed circuit board with a slight dislocation.

FIG. 7B

is a cross-sectional view showing a state after the push-on switch is mounted and soldered on a printed circuit board.

FIG. 8

is a cross-sectional view of a push-on switch in a second exemplary embodiment of the present invention.

FIG. 9

is a cross-sectional view of the push-on switch in a state of being pushed.

FIG. 10

is a perspective view of a push-on switch in a third exemplary embodiment of the present invention.

FIG. 11

is an exploded perspective view of the push-on switch.

FIG. 12

is a perspective view in part of an electronic apparatus, showing how a push-on switch in a fourth exemplary embodiment is mounted thereon.

FIG. 13

is a perspective view in part of an electronic apparatus, showing a state after a push-on switch in a fifth exemplary embodiment is mounted on the printed circuit board.

FIG. 14

is a perspective view of another example, showing a state after mounting.

FIG. 15

is a cross-sectional view of a conventional push-on switch.

FIG. 16

is an exploded perspective view of the conventional push-on switch.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention are described in the following with reference to the drawings.

First Embodiment

FIG. 1

shows a cross-sectional side view of a push-on switch in accordance with a first exemplary embodiment of the present invention;

FIG. 2

shows a perspective view; and

FIG. 3

is an exploded perspective view.

As shown in the

FIGS. 1-3

, a case

21

made of an insulating resin contains a main body

24

of a switch mechanism formed in a front-open recess

21

A, where a central fixed contact point

22

and two outer fixed contact points

23

disposed symmetrically at both sides of the central fixed contact point

22

are provided integrally by an insert molding method in the inner back wall of the recess so that these fixed contact points are exposed to approximately the same height from the wall surface.

The resin case

21

is provided with an overhang

25

which stretches (extends) horizontally in the directions towards both sides and towards the rear from the resin case

21

in the upper part of the main body

24

of the switch mechanism so as to have a size greater than the size of the main body.

The overhang

25

is provided in the rear comers at the right and the left with connection terminals

26

, which are electrically coupled respectively with the central fixed contact point

22

and the outer fixed contact points

23

. Each of the connection terminals

26

consists of a parallel part

26

A which extends along the side and rear walls of overhang

25

and a protrusion part

26

B which stretches sidewise from the parallel part

26

A at the same level as the bottom surface of the overhang

25

.

Although the connection terminal

26

is compatible with the reflow soldering by the parallel part

26

A alone, the extrusion part

26

B contributes to an increase in the connection stability after soldering.

A round domed movable contact

27

made of an elastic metal sheet is housed in the recess

21

A of case

21

with the circumferential edge placed on the outer fixed contact points

23

, so that it opposes the central fixed contact point

22

with a certain predetermined clearance between the contact point

22

and a rear surface of a dome summit

27

A of contact

27

.

In the front of the domed movable contact

27

, a flexible insulating sheet

28

is provided for sealing the recess

21

A of case

21

closed against dust and supporting the domed movable contact

27

.

The insulating sheet

28

not only determines the location of the domed movable contact

27

itself, but it regulates a relative positioning of movable contact

27

with the fixed contact points

22

and

23

.

The insulating sheet

28

may be provided with a pressure sensitive adhesive layer or a sticking agent layer on its surface. These layers further increase a positional accuracy of the movable contact

27

against the fixed contact points

22

and

23

and assure the long-term contact reliability.

An operating body

29

is provided in front of the domed movable contact

27

, via the insulating sheet

28

. The operating body

29

can move to-and-fro to push at its rear end pushing part

29

A the domed movable contact

27

at the dome summit

27

A.

A flange

29

B of the operating body

29

can slide to-and-fro while being guided by a wall

21

B protruding forward from the case

21

, so the operating body

29

can move together. An operating part

29

C provided in the front of flange

29

B protrudes through an opening

30

A of a cover

30

attached to the case

21

.

The cover

30

is attached and fixed to the case

21

, as shown in

FIG. 2

, by hooking claws

30

B in trenches

21

C provided in the case

21

at the right and left.

The cover

30

may be attached and fixed to the case

21

also by other means; for example, providing a dowel (not shown) at the front of case

21

and hammering it flat after it penetrates through a hole provided in the cover

30

.

Now in the following, operation of the above-configured push-on switch in the present embodiment is described.

FIG. 1

shows the push-on switch in an OFF state. When the operating body

29

is pressed at operating part

29

C in a direction as indicated by an arrow, the operating part

29

C moves straight, without any dislocation or tilting, in the direction of the arrow, guided at the flange

29

B by the inner surface of wall part

21

B of case

21

. Pushing part

29

A of the operating body

29

pushes, via insulating sheet

28

, the domed movable contact

27

at the dome summit

27

A.

When the strength of the pressing force goes beyond a certain level, the domed movable contact

27

reverses, which is accompanied a click feeling, to contact with the central fixed contact point

22

at the rear surface at dome summit

27

A. Thus the central fixed contact point

22

and the outer fixed contact points

23

are brought into electrical conduction via the domed movable contact

27

. The two terminals

26

provided in the overhang

25

are brought into electrical contact accordingly. Now the push-on switch is ON, as shown in FIG.

4

.

The domed movable contact

27

is regulated in the position by the insulating sheet

28

and kept in a certain predetermined position during the pressing operation; therefore,

1) a clear click-feeling is generated every time when it is pushed with a certain force, providing a stable electrical contact between the central fixed contact point

22

and the outer fixed contact points

23

, and

2) the operational action of pushing proceeds smoothly, since there is no slide resistance between the pushing part

29

A of operating body

29

and the upper surface of domed movable contact

27

.

When the pressure exerted on the operating body

29

is withdrawn, the domed movable contact

27

restores its original shape with a self restorative elastic force, and returns the operating body

29

to the initial location, bringing the switch to its OFF state as shown in FIG.

1

.

At this state, since the front surface of flange

29

B is in contact with the rear surface of cover

30

, the operating body

29

rests at a certain predetermined position.

As described above, in a push-on switch in the present embodiment, when an operating force is applied to the operating part

29

C, the operating body

29

moves in the same direction in which the operating force is applied and the pushing part

29

A, which is the rearmost part of the operating body

29

, pushes the domed movable contact

27

directly. Thus the push-on switch has a simple structure, using simple constituent components. They can be manufactured through an easy mold machining or other machining processes at low cost. The above-configured side-push type push-on switch provides also a superior feeling of operation.

Next, a method for mounting a push-on switch in the present embodiment, as well as an electronic apparatus containing the push-on switch, are described.

FIGS. 5A and 5B

show methods for mounting a push-on switch in the present exemplary embodiment onto a printed circuit board. There are two methods for mounting, as shown respectively in FIG.

5

A and FIG.

5

B.

A first method for mounting is shown in

FIG. 5A. A

rectangular cut

32

slightly larger than the size of case

21

in the region of main body

24

is provided in the front end of printed circuit board

31

. The cut

32

has a width slightly greater than a width of the main body

24

, and a depth substantially identical to a depth of the main body

24

including the thickness of cover

30

. Two lands

34

are provided on the printed circuit board

31

so that they respectively surround the cut comers, and the lands

34

are each connected with a circuit pattern

33

formed on the printed circuit board

31

.

A push-on switch is held at the overhang

25

provided in the upper part of case

21

to be positioned so that the region of main body

24

is just above the cut

32

of printed circuit board

31

.

And then, it is lowered as indicated by an arrow to have the region of main body

24

inserted in the cut

32

, until the bottom surface of overhang

25

comes in contact with the upper surface of printed circuit board

31

. Then, as shown in

FIG. 6

, the terminal

26

provided in the overhang

25

is positioned on the land

34

of printed circuit board

31

, and the back wall surface of case

21

in the region of main body

24

is in contact against the end-face of the cut

32

.

Finally, after the terminal

26

is connected to the land

34

, an electronic apparatus is completed with the operating part

29

C protruded from the front edge of printed circuit board

31

.

Since the terminal

26

is provided with the extrusion part

26

B, a push-on switch mounted on printed circuit board

31

can be soldered with a broader space to have a high connection strength, even when it is soldered by reflow soldering. Thus a rigid and stable connection can be produced through a reduced number of process steps.

It is preferred to provide the land

34

on printed circuit board

31

with a slight space from the corner of the cut

32

. Forming the land

34

in the above-described pattern arrangement will prevent cream solder, etc. from oozing out into the space of the cut

32

. This contributes to providing a stable mounting quality.

The cut

32

may be tapered narrower towards its lower part, with the case

21

also provided with the corresponding taper in the region of main body

24

. The above-described arrangement eases mounting operation of a push-on switch on a printed circuit board; namely, even if the starting position of a push-on switch is slightly dislocated, it will proceed along the tapered slope of the end-face, eventually reaching to an exact position.

It is preferred to make the width of the cut

32

, where rectangular cut

32

and side surfaces of the case

21

make contact in the region of main body

24

, only slightly larger than the width of the region of main body

24

. Under the above-described arrangement, the sides in the region of main body

24

are supported firmly by the end-faces of the rectangular cut

32

. Thus the play can be minimized, and the push-on switches can be mounted at high placement accuracy.

A second method for mounting a push-on switch in the present embodiment is shown in

FIG. 5B. A

push-on switch is held at the overhang

25

, and the case

21

in the region of main body

24

is inserted horizontally into the rectangular cut

32

from the front as indicated by an arrow. The bottom surface of overhang

25

is kept slightly off the upper surface of printed circuit board

31

.

When the back surface of the case in the region of main body

24

touches the rear end-face of cut

32

, the horizontal inserting motion is stopped, and then the push-on switch is lowered as indicated by the arrow until the bottom surface of overhang makes contact with the upper surface of printed circuit board

31

, as shown in FIG.

6

.

Finally when the terminal

26

is connected with the land

34

, an electronic apparatus is completed, with the operating part

29

C protruding from the front edge of printed circuit board

31

.

In accordance with the present method, a push-on switch in the region of main body

24

is first inserted in to a specified location inside the cut

32

of printed circuit board

31

, and then lowered for fixing. Therefore, the back end of a push-on switch can easily be brought to make contact with the rear end-face of the cut

32

.

The cut

32

may be shaped so that the gap between the end-faces gets narrower towards the rear end, with the case

21

also provided with a corresponding form in the region of main body

24

. The above arrangement eases mounting of a push-on switch on a printed circuit board; namely, even if the starting position of the region of main body

24

is slightly dislocated, it proceeds along the narrowing end-faces of the cut

32

, eventually reaching an exact location.

As described in the foregoing, a push-on switch in the present embodiment is mounted on a printed circuit board

31

with only its portion of the overhang

25

protruded above the printed circuit board

31

. So, it will provide an electronic apparatus with additional room for further downsizing and thinning.

Forming a land

34

over an extended area, in a rearward direction away from the push-on switch, may work as a good remedy for a case as shown in

FIG. 7A

, where a push-on switch is inadvertently placed on a printed circuit board

31

slightly dislocated towards the front, or a once-located push-on switch is slightly dislocated during transfer to the next process step during a manufacturing process. With the above-described land

34

of an extended area, a slightly-dislocated push-on switch may be pulled back as indicated by an arrow of

FIG. 7B

when it is soldered, by the effect of surface tension of the solder. Namely, the push-on switches may be self-aligned to the exact position in the cut

32

of printed circuit board

31

. Thus good mounting quality is obtained.

Since the bottom surface of overhang

25

is kept in close contact with the printed circuit board

31

and the back surface in the region of main body

24

is touching the rear end-face of cut

32

, operating force exerted in parallel with the printed circuit board

31

on the operating body

29

is encountered by the rear end-face of the rectangular cut

32

via the region of main body

24

. Therefore, the soldered portion connecting the land

34

and terminal

26

does not have an undesirable mechanical load applied thereto. Reliable electrical ON/OFF performance can be expected over a long period of time, even after pressing actions are repeatedly exerted on the push-on switch.

Furthermore, by adjusting the thickness of the overhang

25

so that the approximate center of pushing part

29

A substantially coincides with the center of printed circuit board

31

in its thickness direction, the operating force can be better absorbed by the printed circuit board. Under the above-described arrangement, stress on the portion of connection terminal

26

can be reduced still further. Thus a connection stability of the push-on switch with a printed circuit board

31

is improved a step further.

Although the above description has been made only with examples where the push-on switches are mounted with their operating parts

29

C protruded from the front edge of a printed circuit board

31

, an entire part of the push-on switch including the operating part

29

C may be mounted instead behind the front edge of a printed circuit board

31

, so that it is operated using an operating member provided in the apparatus side. Or, instead of mounting a push-on switch in a rectangular cut

32

, it may be mounted, for example, in the inside of a through hole of a certain specific form provided in a printed circuit board

31

. Irrespective of the method of mounting, the push-on switch of the present embodiment makes a significant contribution to the downsizing of electronic apparatus.

The above-described methods for mounting may be applied also to other kinds of electronic components besides the push-on switches of the present invention. The mounting method can be readily used for any of the electronic components that have an overhang in the upper part of the case, where the overhang stretches horizontally in the sidewise directions for a distance greater than the size of main body region of the case and is provided with terminals for connection.

The push-on switch in the present embodiment contains an interposed insulating sheet

28

. However, it is not an essential constituent. By eliminating it, the number of components and the manufacturing process steps becomes less, and the total cost lower.

Second Embodiment

FIG. 8

shows a cross-sectional side view of a push-on switch in a second exemplary embodiment of the present invention. The only difference from the first embodiment is that the operating body

41

is made of an elastic material in the present embodiment. The remaining portions are the same as those of the first embodiment; so, the detailed description of the remaining portions is not repeated.

A rubber material, an elastomer or other elastic resin materials can be used for the operating body

41

.

As shown in

FIG. 8

, the operating body

41

is supported by a cover

30

attached on case

21

, with the operating part

41

A protruding through an opening

30

A of the cover

30

. A front surface of flange

41

B, disposed behind the operating part

41

A, makes contact with the rear surface of cover

30

to regulate location of the operating body

41

.

The operating body

41

moves to-and-fro in the case guided by the wall

21

B of case

21

, so that the operating body

41

can push, at the pushing part

41

C, the dome summit

27

A via insulating sheet

28

.

For the other portions, the same constituent parts as in the first embodiment are used, description of which is eliminated here.

Next, operation of the push-on switch in the present embodiment is described

FIG. 8

shows the switch in an OFF state. When the operating body

41

at operating part

41

A is pressed in a direction as indicated with an arrow, the operating body

41

moves horizontally in the rearward direction and this accompanies a deformation due to elastic compression over a portion of the operating body

41

from operating part

41

A to pushing part

41

C. The pushing part

41

C pushes the domed movable contact

27

at the dome summit

27

A via the insulating sheet

28

and the dome summit

27

A sinks. When the pressing force goes beyond a certain level, the domed movable contact

27

reverses with an accompanying click feeling to come in contact with the central fixed contact point

22

at the rear surface of dome summit

27

A. Thus the central fixed contact point

22

and the outer fixed contact points

23

are brought into contact via the domed movable contact

27

. The terminals

26

are electrically connected accordingly to place the push-on switch in an ON state, as shown in FIG.

9

.

When the pressing force is withdrawn, the domed movable contact is

27

restored to its original shape by an elastic restorative force, and returns the operating body

41

to the initial location bringing the switch back to the OFF state as shown in FIG.

8

.

Since the operating body

41

is made of an elastic material in the present embodiment, it provides a longer operating stroke including a certain length due to the deflection in operating body

41

.

An appropriate material may be selected for the operating body

41

to provide desired operating stroke.

A push-on switch in the present embodiment may be fabricated so that an operating body

41

can undergo a further elastic deformation after the push-on switch is brought into an ON state; namely, the push-on switch may provide an over stroke in the pressing operation. In the above-described configuration, however, attention has to be paid to avoid applying too much load to the contact points section formed of the domed movable contact

27

, central fixed contact point

22

and outer fixed contact points

23

.

Furthermore, a push-on switch in the present embodiment may be assembled, by making use of the elastic force of the operating body

41

, in a way that the operating body

41

itself and the domed movable contact

27

are normally pressed backward for a slight amount. Under the above-described way of fabrication, dislocating of assembled components is curtailed. Significance of this way of fabrication is revealed when the push-on switch is used in, for example, a portable electronic apparatus, where generation of abnormal sounds due to rattling of constituent components can be avoided.

The rattling sound as well as contacting noise may be prevented more effectively by disposing an apparatus side operating member always in contact with the operating part

41

A of operating body

41

so that a certain amount of compression force is present therein.

A method for mounting the push-on switch of the present invention and the state after mounting on a printed circuit board remain the same as those in the first embodiment, so description thereof is omitted here.

Although the operating part

41

A, the flange

41

B and the pushing part

41

C in the present embodiment have been formed integrally as a single-piece operating body

41

, it may be fabricated otherwise. Namely, for example, first making the flange part with a solid material and then combining an elastic operating part and an elastic pushing part together; or combining an integrated elastic body constituting the operating part and the pushing part with the flange part.

Third Embodiment

FIG. 10

shows a perspective view of a push-on switch in a third exemplary embodiment of the present invention.

FIG. 11

is an exploded perspective view of the push-on switch.

As shown in the

FIGS. 10 and 11

, the push-on switch in the present embodiment comes without operating body and cover, as compared with the counterpart in the first embodiment.

Namely, an insulating resin case

51

contains a main body

54

of a switch mechanism formed in a front-open recess

51

A, where a central fixed contact point

52

and two outer fixed contact points

53

, which are disposed symmetrically at both sides of the central fixed contact point

52

, are provided integrally by an insert molding method in an inner recess of the case

51

so that these fixed contact points are exposed from a wall surface of the recess. The resin case

51

is provided with an overhang

55

which stretches horizontally in directions towards both sides and towards the rear from the resin case

51

in the upper part of a region corresponding to the region of main body

54

so as to have a size greater than the size of main body region.

The central fixed contact point

52

and the outer fixed contact points

53

are electrically connected respectively with terminals

56

provided on the overhang

55

, like in the first embodiment.

A domed movable contact

27

is housed in the recess

51

A of case

51

with the circumferential edge placed on the outer fixed contact points

53

, so that it opposes the central fixed contact point

52

keeping a certain predetermined clearance from the reverse surface of the dome summit

27

A. And a flexible insulating sheet

28

is provided for sealing the recess

51

A closed and supporting the domed movable contact

27

at the front surface at the dome summit

27

A for regulating the location. the basic structure remains the same as that in the first embodiment.

The above-configured push-on switch operates on the same basic principle s the first embodiment. So, only a brief description is made here.

Since the push-on switch in the present embodiment has no operating part appearing outside, it is operated by operating pressure given, via insulating sheet

28

, to the domed movable contact

27

using an apparatus side operating member (not shown).

When the pressing force goes beyond a certain level, the domed movable contact

27

reverses and is accompanied by a click feeling to come into contact with the central fixed contact point

52

at the rear surface at dome summit

27

A. Thus the central fixed contact point

52

and the outer fixed contact points

53

are brought into electrical contact, and the corresponding terminals

26

are brought into electrical contact.

When the operating pressure is withdrawn, the domed movable contact

27

is restored to its original shape by an elastic restorative force, and the switch returns to an OFF state.

The method for mounting the push-on switch in the present embodiment and the state after mounting on a printed circuit board are the same as in the first embodiment. So, description of thereof omitted here.

As described above, the push-on switches in the present embodiment can be provided using fewer components, and the shape of case

51

can be much simplified, as compared with the first embodiment. Thus a push-on switch that is cheaper and superior in operational function is provided.

Fourth Embodiment

FIG. 12

is a perspective view showing a push-on switch and an electronic apparatus in part, or a printed circuit board on which the switch is mounted, in a fourth exemplary embodiment of the present invention. As compared with that in the first embodiment, a case

61

of the present embodiment is provided with a protrusion

63

for forming a protrusion/recess area in the region of main body

62

.

The protrusion

63

is provided in two places symmetrically located at both sides of the center line with respect to the width of the case

61

; the protrusions

63

reach upward to an overhang

64

, and downward to the level of a skirt line of case

61

.

As to the structure of other parts and the operation, they remain the same as in the first embodiment. So, description thereof is omitted here.

As shown in

FIG. 12

, a cut

66

of a printed circuit board

65

is provided at the rear end with recesses

67

for accepting protrusions

63

of case

61

.

The push-on switch in the present embodiment is mounted on the printed circuit board

65

with the protrusions

63

engaged in the recesses

66

. By being mounted as above, the push-on switch can be held firmly in the place until it is finally fixed by soldering.

When an operating force is exerted in an oblique direction, movement of the switch is resisted by an engaged structure formed of the protrusions and the recesses, besides a pair of side-faces of the cut

66

. Thus the stress due to the oblique force is better absorbed in the present embodiment by the engaged structure, to provide an enhanced mounting strength.

Since the engaged structure keeps the push-on switch fixed firmly at the central zone including its right and left vicinities, where the influence of operating force is the greatest, the mounting stability is significantly increased. Shape, location, numbers, etc. of the engaging structure are optional.

Fifth Embodiment

FIG. 13

is a perspective view in part of an electronic apparatus, showing a push-on switch in a fifth exemplary embodiment of the present invention mounted on a printed circuit board. The push-on switch in the present embodiment differs from the first embodiment in the way a terminal

71

is provided and in the method by which it is mounted on a printed circuit board.

The push-on switch in the present embodiment is mounted on a printed circuit board in a way such that a push-on switch similar to that in the first embodiment is held upside down. Namely, the top surface of the overhang

25

of case

21

in the first embodiment is positioned at the bottom in the present embodiment, and the bottom surface is placed in contact with the upper surface of printed circuit board

72

to be fixed thereon.

In the present embodiment, a connection terminal

71

provided in the overhang

25

is devised so that it can be connected and fixed by soldering on a circuit pattern

73

of printed circuit board

72

.

As to the structure of other parts and the operation, they remains the same as in the first embodiment. So, no detailed description thereof is repeated here.

Since the push-on switch in the present embodiment is disposed on a printed circuit board

72

with the broad contact area of the overhang

25

down, it can stand alone by itself in a stable manner. This means that the soldering and other procedures can be performed with ease, because the push-on switch is positioned stably thereon. And the operating forces may be dispersed by the broad contact area, so the push-on switch does not easily topple down.

Furthermore, the printed circuit board

72

does not need to be provided with a rectangular cut in the present embodiment, which saves a processing cost.

Still further, the cover

74

may be provided with a reinforcement terminal

74

A, as shown in

FIG. 14

, in addition to the terminal

71

. When the reinforcement terminal

74

A is soldered and fixed on a land

76

of printed circuit board

75

, the mounted strength is further enhanced. The reinforcement terminal

74

A may be utilized also for an anti-electrostatic purpose by electrically connecting the land

76

with the grounding line of the electronic apparatus.

As described in the foregoing, the present invention provides a side-push type push-on switch having a superior operational property. It is mounted and fixed on a printed circuit board with a structure where an operating force is encountered by the end-face of the printed circuit board.

Furthermore, mold machining, manufacturing of constituent components, etc. can be conducted with ease and be less expensive in the present invention even when the push-on switches are miniature-size.

Electronic apparatus can still be downsized and thinned by introducing the push-on switches of the present invention.