Press switch

BACKGROUND OF THE INVENTION

This invention relates to an improved press switch and particularly a press switch that has a simple structure for reducing impedance.

The generally known press switch for channeling or output signal is widely used in various electrical devices such as mobile phone, computer and computer peripheral devices.

FIG. 1

shows the general construction of a conventional press switch which includes a body

6

, a first elastic element

7

and a second elastic element

8

located in the body

1

, a terminal member

9

located in the body

6

above the first and second elastic elements

7

and

8

, and a press element

10

located above the terminal member

9

. When the press element

10

subjects to an external pressing force, the notch

101

at the press element

10

will press against an elastic strip

91

located on the terminal member

9

. The elastic strip

91

in turn will press against the first and second elastic element

7

and

8

whereby to enable the first elastic element

7

bridging and linking the conductive element

61

and

62

for transmitting signals.

Applicant has disclosed an improved tact switch structure in U.S. Pat. No. 6,140,596 which includes a seat body, a first elastic element, a press set, and a closure body. After the first elastic element and the press set have been assembled and disposed in the seat body, the closure body is then combined on the seat body. When an external force is exerted on the press set, the press set will drive the first elastic element to contact and conductively joint with a first and a second electrode.

The examples of the prior art set forth above are capable of channeling and output electric signal. However they all have their share of disadvantages. For instance in the first example, the first and second elastic element

7

and

8

do not have anchoring positions in the body

6

. Hence when the elastic strip

91

presses the first and second elastic element

7

and

8

, displacement of the first and second elastic element

7

and

8

will occur, and might result in poor or no connection between the conductive elements

61

and

62

. Some producers try to remedy this problem by fastening the conductive element

61

to the body

6

, and pre-connect them electrically with the first elastic element

7

. When the first and second elastic element

7

and

8

are being pressed, as long as the first elastic element

7

making contact with the conductive element

62

, electrical connection will be established for transmitting signal. The second example also has similar problem as the first example does. Both of aforesaid examples also have fabrication difficulties and problems, and will result in higher production cost.

Furthermore, as the first example has relative complex structure, it needs more time and process to assemble, and thus has higher production cost. In addition, the conductive element

61

and

62

, and the first and second elastic element

7

and

8

, and terminal member

9

are all made of metal. They have more contact points during contact, and will result in higher impedance and consequently cause signal fading.

SUMMARY OF THE INVENTION

In view of aforesaid disadvantages, it is therefore an object of this invention to provide an improved press switch that has a simple structure and may be assembled with less process and time for reducing production cost.

Another object of this invention is to provide a structure that has smaller number of contact points whereby to greatly reduce impedance so that transmitting signals won't be fading.

In order to achieve aforesaid objects, the press switch according to this invention includes a body, two terminal elements disposed in the body, a first elastic element located in the body, a press element located in the body above the first elastic element, and a face panel covering the body. When the press element subjects to an external pressing force, a second elastic element will be driven to press the first elastic element which in turn links the two terminals for output electric characteristics desired. When the press element is free from the external pressing force, the innate elastic force of the first and second elastic element will push the press element to its original position.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, as well as its many advantages, may be further understood by the following detailed description and drawings, in which:

FIG. 1

is an exploded view of a conventional press switch.

FIG. 2

is a perspective view of this invention.

FIG. 3

is an exploded view of this invention.

FIG. 4A

is a front view of this invention, with the face panel detached.

FIG. 4B

is a front view according to

FIG. 4A

, showing this invention in use.

FIG. 5

is a front view of this invention, with the face panel assembled.

FIG. 6

is a sectional view of this invention taken along line

6

—

6

in FIG.

5

.

FIG. 7A

is a sectional view of this invention taken along line

7

A—

7

A in FIG.

5

.

FIG. 7B

is a sectional view according to

FIG. 7A

, showing this invention in use.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to

FIGS. 2 and 3

, the press switch according to this invention includes a body

1

, two terminal element

2

and

2

′ mounted on the body

1

, a first elastic element

3

located in the body

1

, a press element

4

movably disposed in the body

1

above the first elastic element

3

, and a face panel

5

for covering the body

1

at the front side thereof.

The body

1

has a compartment

11

for housing operation movement, two side walls

12

and

12

′ located at two lateral sides of the compartment

11

, two slots

13

and

13

′ formed respectively in the side walls

12

and

12

′ communicating with the compartment

11

, two stepwise flanges

14

and

14

′ formed respectively at one end of the side walls

12

and

12

′, and an opening

15

formed between the flanges

14

and

14

′ communicating with the compartment

11

. The compartment

11

borders a rear wall of the body

1

which has two symmetrical through holes

16

formed therein. At the front side of the side walls

12

and

12

′, there are a plurality of cavities

17

formed respectively at two lateral sides thereof. Each cavity

17

has a protrusive stub

18

extended outward.

The terminal element

2

and

2

′ have respectively a plate

21

and

21

′ each has a fastening member

22

and

22

′ which can engage with the cavity

17

and the protrusive stub

18

; and a contact finger

23

and

23

′ which may pass through the through holes

16

into the compartment

11

.

The first elastic element

3

is made of an elastic metal and has two ends engageable with the slots

13

and

13

′ (also shown in FIG.

4

A).

The press element

4

has a press head

41

at the top connecting with a neck section

42

located thereunder. The neck section

42

connects with two legs

43

located at two lateral sides which form a trough

44

therebetween. The trough

44

holds a second elastic element

45

therein. The second elastic element

45

is preferably made from rubber. After assembly, the second elastic element

45

is located above the first elastic element

3

. When the press head

41

subjects to an external pressing force and moves the second elastic element

45

downward, the first elastic element

3

will also be pressed downward (referring to FIG.

4

B). The front side of the neck section

42

further has a dimple

46

which is used for sensing the downward movement of the press element

4

(functional details will be explained later).

The face panel

5

has an elastic tongue plate

51

which has a bulged point

52

formed at the tip thereof mating against the dimple

46

when the press element

4

is moved down. At the periphery of the face panel

5

, there are a plurality of fastening elements

53

each has a step ring

54

and a bore

55

formed therein for engaging with the cavity

17

and the stub

18

.

FIGS. 4A and 4B

show this invention has been assembled for use. When the press head

41

receives an external pressing force, the neck section

42

will be moved downward through the opening

15

. Consequently the second elastic element

45

will be moved downward and presses the first elastic element

3

downward. As a result, the first elastic element

3

will make contact with the contact fingers

23

and

23

′ (shown in

FIG. 4B

) thereby establish an electric conduction link to output electric characteristics. When the external pressing force is absent from the press head

41

, the innate elastic force of the first and second elastic element

3

and

45

will push the press element

4

upward to its original position.

Referring to

FIGS. 5 and 6

, when this invention is assembled completely, the face panel

5

is fastened to the body

1

at the front side thereof. This may be done by engaging the bores

55

with the stubs

18

, and pressing the step ring

54

against the cavity

17

until reaching the bottom thereof to make the edge of the step ring

54

skew upward slightly for the bore

55

engaging with the stub

18

firmly and to have the free end of the stub

18

extended outside the front surface of the face panel

5

(shown in FIG.

6

). Then heat melt the free end of the stubs

18

to fill the fastening elements

53

with melted resin for forming a firm and secured engagement between the body

1

and face panel

5

. The fastening thus formed is tightly sealed without gap and may enhance electric characteristics output by the press switch.

Referring to

FIGS. 7A and 7B

, when the press element

4

is pressed downward, the bulged point

52

at the elastic tongue plate

51

will slide on the front surface of the neck section

42

, and will generate a click tremble or sound when reaching the dimple

46

(shown in

FIG. 7B

) whereby users may sense or. hear that the press switch has made electric contact. When the external pressing force is released, the press element

4

will be pushed upward to its original position by the innate elastic force of the first and second elastic element

3

and

45

, and electric contact between the contact finger

23

and

23

′ will be cutoff (also shown in FIG.

4

A).

The construction of this invention is simple, and may be assembled with less processes at a lower cost. Number of contact points is also less, and thus may greatly reduce impedance and may keep output signal from fading.

It may thus be seen that the objects of the present invention set forth herein, as well as those made apparent from the foregoing description, are efficiently attained. While the preferred embodiment of the invention has been set forth for purpose of disclosure, modifications of the disclosed embodiments of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.