Membrane button key structure with a built-in speaker

FIELD OF THE INVENTION

The present invention relates to a membrane button key structure for electronic devices and particularly a membrane button key structure with a built-in speaker.

BACKGROUND OF THE INVENTION

Due to continuous innovations of electronic techniques and rapid developments of digital technologies, 3C information products have become indispensable outfits and helpful working tools for many people. 3C information products include notebook computers, mobile phones, personal digital assistants (PDAs), Palm computers (Palms) and the like. PDA, because of its powerful functions, user-friendliness and light and compact size, has been widely accepted by consumers. In addition, PDA can also include many other functions such as to access the Internet in a wireless fashion, communication, and video/audio enabling. It has becomes a prevailing trend of the information product development nowadays.

Refer to

FIG. 1

for a conventional PDA. It includes a casing

10

, a display panel

12

and a membrane key

14

. The casing

10

has a plurality of openings formed on the surface to match and accommodate the display panel

12

and the membrane key

14

. The keys

140

of the membrane key

14

are extending above the openings. Users can depress the keys

140

to perform the operations of the PDA. The information are displayed on the display panel

12

.

Refer to

FIG. 2

for the membrane key of adopted by conventional techniques. The membrane key

20

includes a four-way key

21

and a plurality of hot keys

22

. The keys

21

and

22

are interconnected by a membrane

23

. The entire membrane key

20

is integrally formed from a pliable rubber. The four-way key

21

has four bulged points

24

located on a lower side of four corners. Each hot key

22

also has a bulged point

22

located thereunder. There is a circuit board

25

located below the membrane key

20

. The circuit board

25

has a plurality of touch switches

26

located on the surface thereof. The bulged points

24

below the keys

21

and

22

correspond to the touch switches

26

of the circuit board

25

. Users may enter input commands on the PDA by depressing the keys

21

and

22

to move the bulged points

24

located therebelow in contact with the touch switches

26

of the circuit board

25

. The input commands are processed and the results are displayed on the display panel (not shown in the drawings).

These days, PDA equipped with video/audio or mobile phone capabilities has become a hotly pursued trend. One of the critical elements to achieve the aforesaid functions is the speaker. To make the PDA competitive, it must by lean and light, and has a big enough display screen. To meet those requirements, conventional techniques of PDA have fully utilized the internal space of the casing for the configuration of the necessary elements and keys. It is very difficult to allocate an additional space for the speaker. When trying to adopt the conventional techniques to add the speaker on the front side of the PDA without increasing the total size, the size of the display panel has to be shrunk. To keep the speaker on the front side of the PDA without reducing the size of the display panel, total size of the PDA should be increased. To install the speaker on the rear side of the PDA will increase the total thickness. Besides, when the speaker is located on the rear side of the PDA, the audio quality is not desirable. When it is coupled with the mobile phone, the voice output from the rear side has the risk of being eavesdropped.

Because of the conventional techniques have difficulty to include the speaker in the PDA and still meet the requirements of lean and light and a large enough display screen, it is necessary to develop new techniques to resolve the problem.

SUMMARY OF THE INVENTION

Therefore the primary object of the invention is to provide a membrane button key structure with a built-in speaker to offer PDAs or the related electronic products with audio function without increasing the thickness and size of the product, or reducing the size of the display screen.

The membrane button key structure with a built-in speaker of the invention is adopted for use on PDAs or the related electronic products. The PDA includes a circuit board which has a plurality of touch switches and a carved opening on the surface thereof. The invention includes a membrane key, a bottom lid and a speaker. The membrane key consists of a four-way key and a plurality of hot keys interconnected by a membrane which is integrally made from a pliable rubber. The four-way key has four bulged points located on bottom side of four corners. Each hot key also has a bulged point located on the bottom in the center thereof. When the membrane key is coupled above the circuit board, each key located under the membrane key corresponds to a touch switch of the circuit board. The center of the four-way key is above the carved opening. The bottom lid is under the carved opening and forms a housing compartment with the four-way key for housing the speaker in the middle thereof. The space between the speaker and the four-way key becomes an upper acoustic chest and the space between the speaker and the bottom lid becomes a lower acoustic chest.

The invention aims at installing the speaker below the four-way key of the membrane key without increasing the total thickness and size of the PDA, or reducing the size of the display screen. The circuit board below the four-way key is properly carved to coupled with a bottom lid to form a housing compartment with the four-way key. Therefore, the speaker may be installed in the PDA to generate a desired audio effect without increasing the total thickness and size of the PDA, or reducing the size of the display screen. In order to form the carved opening on the circuit board, the circuit layout on the circuit board has to be properly designed to prevent from being interrupted. In addition, the interior of the four-way key and function keys is formed in a hollow manner to increase the acoustic space of the acoustic chest to improve the sound quality of the speaker. The bulged points to contact the touch switches of the circuit board are maintained. The membrane connecting the keys has troughs formed on the bottom thereof to communicate with the hollow space of the hollow keys so that the space of the acoustic chest may be increased to improve the sound quality of the speaker.

The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:

FIG. 1

is a perspective view of a conventional PDA.

FIG. 2

is a schematic view of a conventional membrane button key.

FIG. 3

is a schematic view of a circuit board of the invention.

FIG. 4

is a schematic view of a membrane button key structure of the invention.

FIG. 5

is a bottom view of the membrane key of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The membrane button key structure with a built-in speaker of the invention has a housing compartment formed on the bottom of the membrane key to house a speaker so that the coupled electronic product such as a PDA can equip with audio function without increasing the total thickness or size of the product, or reducing the size of the display screen. Details of the invention are depicted below referring to the embodiment.

The membrane button key structure with a built-in speaker of the invention is adopted on PDAs or related electronic products. Whatever the products, they must have a circuit board

30

located therein to couple with the membrane button key structure. Refer to

FIG. 3

for an embodiment of the invention, the circuit board

30

has a plurality of touch switches

32

and a carved opening

34

.

Referring to

FIG. 4

, the membrane button key structure of the invention includes a membrane key

40

, a bottom lid

41

and a speaker

42

. The membrane key

40

consists of a four-way key

43

and a plurality of hot keys

44

. The keys

43

and

44

are connected by a membrane

45

integrally made from a pliable rubber. The four-way key

43

have four bulged points

46

formed at four corners on the bottom side thereof. Each hot key

44

also has a bulged point

46

located on the bottom side in the center. When the membrane key

40

is coupled with the circuit board

30

thereabove, each bulged point

46

on the bottom of the membrane key

40

corresponds to one touch switch

32

of the circuit board

30

. In addition, the four-way key

43

is located above the carved opening

34

. The periphery of the carved opening

34

also has four touch switches

32

corresponding to the four bulged points

46

of the four-way key

43

. The bottom lid

41

is located below the carved opening

34

of the circuit board

30

to form a housing compartment with the four-way key

43

to accommodate the speaker

42

. When the speaker

42

is held in the housing compartment, the extra space it forms with the four-way key

43

becomes an upper acoustic chest

47

of the speaker

42

, while another extra space it forms with the bottom lid

41

becomes a lower acoustic chest

48

of the speaker

42

.

As the speaker is housed in the space formed below the four-way key and the carved opening of the circuit board, it can provide the audio effect without increasing the total thickness and size of the PDA, or reducing the size of the display panel. In order to form the carved opening on the circuit board, the circuit design of the circuit board has to take special considerations to spare the opening required to avoid circuit interruption.

In addition, the size of the acoustic chest directly affects the audio quality of the speaker. In order to improve the quality of the speaker, the four-way key

43

and the hot keys

44

of the invention are made with a hollow interior. Only the bulged points

46

required to contact the touch switches on the circuit board remain. The bottom of the membrane

45

is formed with troughs

49

to connect and communicate with the hollow interior of every key

43

and

44

, and the compartment (upper acoustic chest) formed below the four-way key

43

to form a greater space for the upper acoustic chest (as shown in FIG.

5

). Thus audio quality of the speaker can be improved.

While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment 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.