Keyboard device and manufacturing method thereof

A keyboard device and a manufacturing method of the keyboard device are provided. The keyboard device includes a base plate, a membrane circuit board and a key. A connecting structure with an upper connecting part is protruded from the base plate. The membrane circuit board includes a first film layer with an extension part. A clearance space is formed between the extension part and the base plate. An end part of the stabilizer bar of the keycap is clamped between the upper connecting part and the extension part. While the stabilizer bar is moved, the end part of the stabilizer bar is slid between the upper connecting part and the extension part. Moreover, the end part of the stabilizer bar and the extension part are interfered with each other and sunken downwardly into the clearance space.

FIELD OF THE INVENTION

The present invention relates to an input device, and more particularly to a keyboard device.

BACKGROUND OF THE INVENTION

Generally, the widely-used peripheral input device of a computer system includes for example a mouse device, a keyboard device, a trackball device, or the like. Via the keyboard device, characters or symbols can be inputted into the computer system directly. As a consequence, most users and most manufacturers of input devices pay much attention to the development of keyboard devices.

The structures and the functions of a conventional keyboard device1will be illustrated as follows. Please refer toFIGS. 1, 2 and 3.FIG. 1is a schematic top view illustrating the outer appearance of a conventional keyboard device.FIG. 2is a schematic exploded view illustrating a portion of the keyboard device ofFIG. 1.FIG. 3is a schematic cross-sectional view illustrating the assembled structure of the keyboard device ofFIG. 2. For example, the keyboard device as shown inFIGS. 1, 2 and 3is disclosed in Taiwanese Patent No. TWI512774.

The conventional keyboard device1comprises plural keys10′, a base plate11and a membrane circuit board12. The membrane circuit board12comprises plural membrane switches (not shown) corresponding to the plural keys10′. Each of the plural keys10′ comprises a keycap101, at least one scissors-type connecting element102and at least one elastic element103. The scissors-type connecting element102is connected between the keycap101and the base plate11. Moreover, the scissors-type connecting element102comprises a first frame1021and a second frame1022. The second frame1022is pivotally coupled to the first frame1021. Consequently, the first frame1021and the second frame1022can be swung relative to each other. The elastic element103is arranged between the keycap101and the base plate11. Moreover, the elastic element103comprises a contacting part (not shown).

While the keycap101of any key10′ is depressed and moved downwardly relative to the base plate11, the first frame1021and the second frame1022of the scissors-type connecting element102are switched from an open-scissors state to a stacked state. Moreover, as the keycap101is moved downwardly to compress the elastic element103, the corresponding membrane switch is pushed and triggered by the contacting part of the elastic element103. Consequently, the keyboard device1generates a corresponding key signal. When the key10′ is no longer depressed, the keycap101is moved upwardly relative to the base plate11in response to an elastic force of the elastic element103. Meanwhile, the first frame1021and the second frame1022are switched from the stacked state to the open-scissors state again, and the keycap101is returned to its original position.

The key10′ further comprises two stabilizer bars104. Each stabilizer bar104comprises a transverse bar part1041and two hook parts1042. The two hook parts1042are located at two ends of the transverse bar part1041, respectively.

The base plate11comprises a plate body112and plural connecting structures111. The plate body112is located under the membrane circuit board12. The plural connecting structures111are protruded upwardly from the plate body112and penetrated through the membrane circuit board12. Each connecting structure111comprises an upper connecting part1112and plural lateral connecting parts1113. The plural lateral connecting parts1113are connected with the upper connecting part1112. Moreover, plural locking holes1111are formed between the connecting part1112, the plural lateral connecting parts1113and the plate body112. The transverse bar part1041of the each stabilizer bar104is pivotally coupled to the keycap101of the key10′. The two hook parts1042of each stabilizer bar104are penetrated through the locking holes1111of the corresponding connecting structure111.

Please refer toFIG. 3again. While the keycap101of the key10′ is moved upwardly or downwardly relative to the base plate11, the stabilizer bars104are moved in the direction D11, the direction D12, the direction D13or the direction D14, and rotated in the direction D15or the direction D16. By this design, the key10′ is kept stable and not inclined while the key10′ is moved upwardly or downwardly relative to the base plate11. Moreover, this design is helpful to increase the strength of the keycap101.

Please refer toFIGS. 2 and 3again. The plate body112of the base plate11comprises plural accommodation spaces114, which are in slot forms. The positions of the accommodation spaces114are determined according to movable ranges of the hook parts1042of the corresponding stabilizer bars104. That is, the positions of the accommodation spaces114are substantially located under the movable ranges of the hook parts1042. The membrane circuit board12comprises an extension part125. The accommodation spaces114are covered by the extension part125. While each stabilizer bar104is moved with the keycap101, only the hook parts1042of the stabilizer bar104are contacted with the extension part125of the membrane circuit board12. In addition, the hook parts1042and the extension part125are sunken downwardly into the accommodation spaces114of the plate body112. That is, while the stabilizer bar104is moved, the stabilizer bar104is not directly contacted with the plate body112of the base plate11. Since the stabilizer bar104does not directly collide with the plate body112of the base plate11, the sound resulted from the collision will be reduced. In such way, the efficacy of reducing the noise is achieved.

As mentioned above, the plate body112of the base plate11comprises the slot-form accommodation spaces114for reducing the noise, and the extension part125of the membrane circuit board12is used to cover the accommodation spaces114and support the hook parts1042of the stabilizer bar104. However, since the extension part125of the membrane circuit board12is made of a soft material and there is no supporting structure under the extension part125, the action of the stabilizer bar104is not stable. In other words, the function of stabilizing the key10′ by the stabilizer bar104is largely reduced.

Recently, the trend of designing the keyboard device1is toward miniaturization. Consequently, the diameter of the stabilizer bar104is gradually reduced. After the hook part1042of the stabilizer bar104is penetrated through the corresponding locking hole1111of the connecting structure111, the vacant spaces between the hook part1042and the upper connecting part1112and the plural lateral connecting parts1113of the connecting structure111become larger. Consequently, while the stabilizer bar104is moved with the keycap101, the hook part1042of the stabilizer bar104readily collides with the upper connecting part1112and the plural lateral connecting parts1113to generate a sound. Especially, the sound-reducing design of the conventional keyboard device1results in another drawback. After the hook part1042is sunken downwardly into the corresponding accommodation space114and the hook part1042is moved upwardly in response to an elastic force of the extension part125, the hook part1042strongly collides with the upper connecting part1112of the connecting structure111because of the elastic force. Consequently, the intensity of the sound becomes louder. Generally, the sound from collision is unpleasant noise to the user.

In other words, the conventional keyboard device1needs to be further improved.

SUMMARY OF THE INVENTION

An object of the present invention provides a keyboard device having a function of reducing noise. An end part of a stabilizer bar is clamped between an upper connecting part of a connecting structure of a base plate and an extension part of a first film layer of a membrane circuit board. While the stabilizer bar is moved, the end part of the stabilizer bar is slid between the upper connecting part and the extension part. Moreover, the end part of the stabilizer bar and the extension part are interfered with each other, and the end part of the stabilizer bar and the extension part are sunken downwardly into a clearance space between the extension part and the base plate.

In accordance with an aspect of the present invention, there is provided a keyboard device. The keyboard device includes a membrane circuit board, a base plate and a key. The membrane circuit board includes a membrane switch, a first film layer and a second film layer. The first film layer and the second film layer are stacked on each other. The first film layer includes an extension part. The extension part is extended over a periphery of the second film layer. The base plate includes a plate body and a connecting structure. The plate body is located under the membrane circuit board. The connecting structure is protruded upwardly from the plate body and penetrated through the membrane circuit board. The connecting structure includes an upper connecting part and a lateral connecting part. The lateral connecting part is connected with the upper connecting part. A locking hole is formed between the connecting part, the lateral connecting part and the plate body. The plate body is located under the extension part. A clearance space is formed between the extension part and the plate body. The key includes a keycap and a stabilizer bar. While the keycap is moved downwardly relative to the membrane circuit board, the membrane switch is triggered. The stabilizer bar is connected between the keycap and the base plate. An end part of the stabilizer bar is penetrated through the locking hole and clamped between the upper connecting part and the extension part. While the keycap is moved upwardly or downwardly relative to the base plate, the end part of the stabilizer bar is slid between the upper connecting part and the extension part, the end part of the stabilizer bar and the extension part are interfered with each other, and the end part of the stabilizer bar and the extension part are sunken downwardly into the clearance space.

In accordance with another aspect of the present invention, there is provided a manufacturing method for manufacturing the keyboard device of the present invention. Firstly, in a step (P1), a diameter of the stabilizer bar and/or a first vertical distance between a bottom surface of the upper connecting part and the extension part is changed. Consequently, an extent of the interference between the end part of the stabilizer bar and the extension part is adjusted. In a step (P2), an extensible range of the extension part is determined according to a movable range of the end part of the stabilizer bar.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer toFIGS. 4, 5 and 6.FIG. 4is a schematic top view illustrating the outer appearance of a keyboard device according to a first embodiment of the present invention.FIG. 5is a schematic exploded view illustrating a portion of the keyboard device ofFIG. 4and taken along a viewpoint.FIG. 6is a schematic exploded view illustrating a portion of the keyboard device ofFIG. 4and taken along another viewpoint. For succinctness, only one key20′ and the related components are shown inFIGS. 5 and 6.

The keyboard device2comprises plural keys20and20′, a base plate21and a membrane circuit board22. These keys20and20′ are classified into some types, e.g., ordinary keys, numeric keys and function keys. When one of the keys20and20′ is depressed by the user's finger, the keyboard device2generates a corresponding key signal to a computer (not shown), and thus the computer executes a function corresponding to the depressed key. For example, when an ordinary key is depressed, a corresponding English letter or symbol is inputted into the computer. When a numeric key is depressed, a corresponding number is inputted into the computer. In addition, the function keys (F1˜F12) can be programmed to provide various quick access functions.

FIG. 7is a schematic exploded view illustrating the membrane circuit board of the keyboard device as shown inFIG. 4. The membrane circuit board22comprises plural film layers. The thickness of each film layer is presented herein for purpose of illustration and description only. For succinctness, only one upper contact, one lower contact and one perforation are shown inFIG. 7. As shown inFIG. 7, the membrane circuit board22comprises a first film layer, a second film layer and a third film layer, which are stacked on each other. In an embodiment, an upper film layer222, a lower film layer223and an intermediate film layer224are the first film layer, the second film layer and the third film layer, respectively. A first circuit pattern2221is formed on a bottom surface of the upper film layer222. The first circuit pattern2221comprises plural upper contacts2222corresponding to the plural keys20and20′. A second circuit pattern2231is formed on a top surface of the lower film layer223. The second circuit pattern2231comprises plural lower contacts2232corresponding to the plural upper contacts2222. Each of the upper contacts2222and the corresponding lower contact2232are separated from each other by a spacing distance. Moreover, each of the upper contacts2222and the corresponding lower contact2232are collectively defined as a membrane switch221. Moreover, for maintaining the spacing distance between each upper contact2222and the corresponding lower contact2232, the intermediate film layer224is arranged between the upper film layer222and the lower film layer223. In addition, the intermediate film layer224comprises plural perforations2241corresponding to the plural upper contacts2222and the plural lower contacts2232. Preferably but not exclusively, at least one of the upper film layer222, the lower film layer223and the intermediate film layer224is made of polycarbonate (PC), polyethylene terephthalate (PET), polymethylmethacrylate (PMMA), polyurethane (PU) or polyimide (PI).

Each of the plural keys20and20′ comprises a keycap201, a connecting element202and an elastic element203. The connecting element202is connected between the keycap201and the base plate21. Through the connecting element202, the keycap201is movable upwardly or downwardly relative to the base plate21. The elastic element203is arranged between the keycap201and the base plate21. Moreover, the elastic element203comprises a contacting part2031. In an embodiment, the keycap201comprises fixed hooks2011and movable hooks2012. The fixed hooks2011and the movable hooks2012are disposed on a bottom surface of the keycap201. In an embodiment, the connecting element202is a scissors-type connecting element. Moreover, the connecting element202comprises a first frame2021and a second frame2022. The second frame2022is pivotally coupled to the first frame2021. The first frame2021is an inner frame, and the second frame2022is an outer frame.

The base plate21comprises a plate body212, plural first base plate hooks213and plural second base plate hooks214. The plate body212is located under the membrane circuit board22. The plural first base plate hooks213and the plural second base plate hooks214are protruded upwardly from the plate body212and penetrated through the membrane circuit board22.

The first end20211of the first frame2021is connected with the corresponding fixed hook2011of the keycap201. The second end20212of the first frame2021is connected with the second base plate hook214of the base plate21. The first end20221of the second frame2022is connected with the corresponding first base plate hook213of the base plate21. The second end20222of the second frame2022is connected with the movable hook2012of the keycap201. Due to the above structure, the first frame2021and the second frame2022can be swung relative to each other. Consequently, the first frame2021and the second frame2022are switched from a stacked state to an open-scissors state or switched from the open-scissors state to the stacked state. The connecting relationships between the connecting element202, the base plate21and the keycap201are presented herein for purpose of illustration and description only.

While the keycap201of any key20or20′ is depressed and moved downwardly relative to the base plate21, the first frame2021and the second frame2022of the connecting element202are switched from the open-scissors state to the stacked state. Moreover, as the keycap201is moved downwardly to compress the elastic element203, the corresponding upper contact2222is pushed and triggered by the contacting part2031of the elastic element203. Consequently, the corresponding upper contact2222is contacted with the corresponding lower contact2232through the corresponding perforation2241. In such way, the corresponding membrane switch221is electrically conducted, and the keyboard device2generates a corresponding key signal. When the keycap201of the key20or20′ is no longer depressed, the keycap201is moved upwardly relative to the base plate21in response to an elastic force of the elastic element203. Meanwhile, the first frame2021and the second frame2022are switched from the stacked state to the open-scissors state. Consequently, the keycap201is returned to its original position.

Please refer toFIGS. 4, 5 and 6again. The length L2of the key20′ is much larger than the width W2of the key20′. The key20′ further comprises two stabilizer bars204. Each stabilizer bar204is connected between the key20′ and the base plate21. The keycap201of the key20′ further comprises plural stabilizer lock parts2013. The stabilizer lock parts2013are disposed on a bottom surface of the keycap201. The base plate21further comprises plural connecting structures211. The plural connecting structures211are protruded upwardly from the plate body212and penetrated through the membrane circuit board22. Each connecting structure211comprises an upper connecting part2112and plural lateral connecting parts2113. The plural lateral connecting parts2113are connected with the upper connecting part2112. Moreover, plural locking holes2111are formed between the connecting part2112, the plural lateral connecting parts2113and the plate body212. The end parts2042of the stabilizer bars204are penetrated through the corresponding locking holes2111. In this embodiment, each stabilizer bar204further comprises a transverse bar part2041. The transverse bar part2041is inserted into the corresponding stabilizer lock part2013of the keycap201and pivotally coupled to the keycap201. The end part2042of each stabilizer bar204are hook parts, which are located at two ends of the transverse bar part2041.

FIG. 8schematically illustrates the actions of the stabilizer bar of the keyboard device as shown inFIG. 4. For succinctness, only the stabilizer bars204and the related components are shown inFIG. 8. The keycap201and the connecting element202are not shown inFIG. 8. While the keycap201of the key20′ is moved upwardly or downwardly relative to the base plate21, the stabilizer bars204are moved in the direction D21or the direction D22, and/or moved in the direction D23or the direction D24, and/or moved in the direction D25or the direction D26, and/or rotated in the direction D27or the direction D28. In addition, the transverse bar parts2041are rotated relative to the corresponding stabilizer lock parts2013of the keycap201. Consequently, while the key20′ is moved upwardly or downwardly relative to the base plate21, the key20′ is kept stable and not inclined. Moreover, this design is helpful to increase the strength of the keycap201.

Please refer toFIGS. 7, 9 and 10.FIG. 9is a schematic cross-sectional view illustrating portions of the stabilizer bar, the base plate and the membrane circuit board of the keyboard device as shown inFIG. 4and taken along a viewpoint.FIG. 10is a schematic cross-sectional view illustrating portions of the stabilizer bar, the base plate and the membrane circuit board of the keyboard device as shown inFIG. 4and taken along another viewpoint. For clearly illustrating the structures of various layers, the sizes and thicknesses of the stabilizer bar, the base plate and the membrane circuit board as shown inFIGS. 9 and 10are presented herein for purpose of illustration and description only.

The upper film layer222of the membrane circuit board22comprises an extension part2223. The extension part2223is externally extended over a periphery of the intermediate film layer224and a periphery of the lower film layer223. Consequently, a clearance space23is formed between the extension part2223and the underlying plate body212. There is a first vertical distance S1between the bottom surface of the upper connecting part2112of the connecting structure211and the extension part2223. There is a second vertical distance S2between the bottom surface of the upper connecting part2112of the connecting structure211and the plate body212of the base plate21. When the end part2042of the stabilizer bar204is penetrated through the corresponding locking hole2111of the connecting structure211, a portion of the end part2042is clamped between the upper connecting part2112of the connecting structure211and the extension part2223of the upper film layer222. Preferably but not exclusively, the diameter S0of the stabilizer bar204is larger than the first vertical distance S1.

As mentioned above, the structure of the keyboard device is specially designed. While the keycap201of the key20′ is moved upwardly or downwardly relative to the base plate21, the end part2042of the stabilizer bar204is slid between the upper connecting part2112of the connecting structure211and the extension part2223of the upper film layer222. Moreover, the end part2042of the stabilizer bar204and the extension part2223of the upper film layer222are interfered with each other. When the end part2042of the stabilizer bar204and the extension part2223of the upper film layer222are interfered with each other, the end part2042of the stabilizer bar204and the extension part2223of the upper film layer222are sunken downwardly into the clearance space23.

In accordance with a feature of the present invention, the diameter S0of the stabilizer bar204is larger than the first vertical distance S1. The end part2042of the stabilizer bar204is clamped between the upper connecting part2112of the connecting structure211and the extension part2223of the upper film layer222. While the stabilizer bar204is moved, the end part2042of the stabilizer bar204and the extension part2223of the upper film layer222are interfered with each other. Consequently, the gap between the end part2042of the stabilizer bar204and the upper connecting part2112of the connecting structure211and the gaps between the end part2042of the stabilizer bar204and the lateral connecting parts2113of the connecting structure211are effectively reduced. While the stabilizer bar204is moved, the upper connecting part2112or the lateral connecting parts2113of the connecting structure211are not directly collided by the end part2042of the stabilizer bar204. Consequently, the unpleasing sound is reduced.

As mentioned above, the plate body212of the base plate21is located under the clearance space23. That is, the site of the base plate21corresponding to the clearance space23is not a through-hole. Consequently, the end part2042of the stabilizer bar204and the extension part2223of the upper film layer222can be sunken downwardly to a limited extent. Since the end part2042of the stabilizer bar204is not extremely sunken in the downward direction, the gap between the end part2042of the stabilizer bar204and the upper connecting part2112of the connecting structure211is not very large. Consequently, when the end part2042of the stabilizer bar204is moved upwardly to collide with the upper connecting part2112of the connecting structure211in response to an elastic force of the extension part2223of the upper film layer222, the generated sound is not very loud.

Please refer toFIGS. 8 and 9again. In this embodiment, the two clearance spaces23corresponding to the end parts2042of the two stabilizer bars204are separated from each other. Consequently, the extents of the interference between the end parts2042of the two stabilizer bars204and the extension part2223of the upper film layer222are substantially equal. In this embodiment, a portion of the lower film layer223and a portion of the intermediate film layer224are arranged between the two clearance spaces23corresponding to the end parts2042of the two stabilizer bars204. Moreover, the lower film layer223and the intermediate film layer224between the two clearance spaces23also have the function of supporting the extension part2223. Consequently, when the end part2042of the stabilizer bar204and the extension part2223are interfered with each other, the deformable extent of the extension part2223is reduced. Under this circumstance, the sunken extents of the end part2042of the stabilizer bar204toward the clearance spaces23are effectively controlled, and the gaps between the end parts2042of the stabilizer bar204and the upper connecting parts2112of the connecting structure211are effectively controlled.

Please refer toFIG. 10. As mentioned above, the site of the base plate21corresponding to the clearance space23is not a through-hole. In other words, the sunken end parts2042of the stabilizer bar204can be supported by the plate body212of the base plate21. Consequently, the operating stability of the stabilizer bar204is not adversely affected. Moreover, the extensible range S3of the extension part2223of the upper film layer222is determined according to the movable range of the end part2042of the stabilizer bar204in the direction D21, the direction D22, the direction D25and the direction D26. Consequently, even if the site of the base plate21corresponding to the clearance space23is not a through-hole, the end part2042of the stabilizer bar204and the plate body212of the base plate21do not collide with each other to generate the sound.

Please refer toFIGS. 11 and 12.FIG. 11is a schematic cross-sectional view illustrating portions of a stabilizer bar, a base plate and a membrane circuit board of a keyboard device according to a second embodiment of the present invention and taken along a viewpoint.FIG. 12is a schematic cross-sectional view illustrating portions of the stabilizer bar, the base plate and the membrane circuit board of the keyboard device ofFIG. 11and taken along another viewpoint. For clearly illustrating the structures of various layers, the sizes and thicknesses of the stabilizer bar, the base plate and the membrane circuit board as shown inFIGS. 11 and 12are presented herein for purpose of illustration and description only.

The structures and functions of the components of the keyboard device which are identical to those of the first embodiment are not redundantly described herein. In comparison with the first embodiment, the diameter S0′ of the stabilizer bar204′ is distinguished, and the second vertical distance S2′ between the bottom surface of the upper connecting part2112′ of the connecting structure211′ and the plate body212′ of the base plate is distinguished. In this embodiment, the end part2042′ of the stabilizer bar204′ is clamped between the upper connecting part2112′ and the intermediate film layer224′ of the membrane circuit board22′. Especially, the intermediate film layer224′ comprises an extension part2243′. The extension part2243′ is externally extended over a periphery of the upper film layer222′ and a periphery of the lower film layer223′. Consequently, a clearance space23′ is formed between the extension part2243′ and the underlying plate body212′. When the end part2042′ of the stabilizer bar204′ is penetrated through the corresponding locking hole2111′ of the connecting structure211′, a portion of the end part2042′ is clamped between the upper connecting part2112′ of the connecting structure211′ and the extension part2243′ of the intermediate film layer224′. Preferably, the diameter S0′ of the stabilizer bar204′ is larger than the first vertical distance SF between the bottom surface of the upper connecting part2112′ of the connecting structure211′ and the extension part2243′ of the intermediate film layer224′.

As mentioned above, the structure of the keyboard device is specially designed. While the keycap (not shown) of the key (not shown) is moved upwardly or downwardly relative to the base plate21′, the end part2042′ of the stabilizer bar204′ is slid between the upper connecting part2112′ of the connecting structure211′ and the extension part2243′ of the intermediate film layer224′. Moreover, the end part2042′ of the stabilizer bar204′ and the extension part2243′ of the intermediate film layer224′ are interfered with each other. When the end part2042′ of the stabilizer bar204′ and the extension part2243′ of the intermediate film layer224′ are interfered with each other, the end part2042′ of the stabilizer bar204′ and the extension part2243′ of the intermediate film layer224′ are sunken downwardly into the clearance space23′.

In accordance with a feature of the present invention, the diameter S0′ of the stabilizer bar204′ is larger than the first vertical distance SF. The end part2042′ of the stabilizer bar204′ is clamped between the upper connecting part2112′ of the connecting structure211′ and the extension part2243′ of the intermediate film layer224′. While the stabilizer bar204′ is moved, the end part2042′ of the stabilizer bar204′ and the extension part2243′ of the intermediate film layer224′ are interfered with each other. Consequently, the gap between the end part2042′ of the stabilizer bar204′ and the upper connecting part2112′ of the connecting structure211′ and the gaps between the end part2042′ of the stabilizer bar204′ and the lateral connecting parts2113′ of the connecting structure211′ are effectively reduced. While the stabilizer bar204′ is moved, the upper connecting part2112′ or the lateral connecting parts2113′ of the connecting structure211′ are not directly collided by the end part2042′ of the stabilizer bar204′. Consequently, the intensity of the unpleasing sound is reduced.

As mentioned above, the plate body212′ of the base plate21′ is located under the clearance space23′. That is, the site of the base plate21′ corresponding to the clearance space23′ is not a through-hole. Consequently, the end part2042′ of the stabilizer bar204′ and the extension part2243′ of the intermediate film layer224′ can be sunken downwardly to a limited extent. Since the end part2042′ of the stabilizer bar204′ is not extremely sunken in the downward direction, the gap between the end part2042′ of the stabilizer bar204′ and the upper connecting part2112′ of the connecting structure211′ is not very large. Consequently, when the end part2042′ of the stabilizer bar204′ is moved upwardly to collide with the upper connecting part2112′ of the connecting structure211′ in response to an elastic force of the extension part2243′ of the intermediate film layer224′, the generated sound is not very loud.

As mentioned above, the site of the base plate21′ corresponding to the clearance space23′ is not a through-hole. In other words, the sunken end parts2042′ of the stabilizer bar204′ can be supported by the plate body212′ of the base plate21′. Consequently, the operating stability of the stabilizer bar204′ is not adversely affected. Moreover, the extensible range S3′ of the extension part2243′ of the intermediate film layer224′ is determined according to the movable range of the end part2042′ of the stabilizer bar204′. Consequently, even if the site of the base plate21′ corresponding to the clearance space23′ is not a through-hole, the end part2042′ of the stabilizer bar204′ and the plate body212′ of the base plate21′ do not collide with each other to generate the sound.

Please refer toFIGS. 13, 14 and 15.FIG. 13is a schematic perspective view illustrating a membrane circuit board of a keyboard device according to a third embodiment of the present invention and taken along a viewpoint and taken along a viewpoint.FIG. 14is a schematic perspective view illustrating the membrane circuit board ofFIG. 13and taken along a viewpoint and taken along another viewpoint.FIG. 15is a schematic cross-sectional view illustrating portions of a stabilizer bar, a base plate and the membrane circuit board of the keyboard device according to the third embodiment of the present invention. The structures and functions of the components of the keyboard device which are identical to those of the first embodiment are not redundantly described herein.

In the first embodiment as shown inFIGS. 6 and 7, the edges22231,22232and22233of the extension part2223are fixed edges, and the edge22234of the extension part2223is a floated edge. In the upper film layer222″ of this embodiment, the edge22231″ of the extension part2223″ is a fixed edge, and the edges22232″,22233″ and22234″ of the extension part2223″ are floated edges. In comparison with the first embodiment, the two clearance spaces23″ corresponding to the end parts2042″ of the two stabilizer bars204″ are not separated from each other by the lower film layer223″ and the intermediate film layer224″. That is, the two clearance spaces23″ corresponding to the end parts2042″ of the two stabilizer bars204″ are collaboratively defined as the same clearance space.

The present invention further comprises a manufacturing method for manufacturing the keyboard device of the present invention.FIG. 16is a flowchart illustrating a manufacturing method for manufacturing a keyboard device according to an embodiment of the present invention. The manufacturing method comprises steps P1 and P2.

In the step P1, a diameter of the stabilizer bar and/or a first vertical distance between a bottom surface of the upper connecting part and the extension part is changed, so that an extent of the interference between the end part of the stabilizer bar and the extension part is adjusted. The tactile feel of depressing the key and the sound-reducing efficacy after depressing the key will be enhanced.

In the step P1, the end part of the stabilizer bar is clamped between the upper connecting part and the extension part of the first film layer, and the first film layer is selected from at least one of the upper film layer and the intermediate film layer of the membrane circuit board according to the diameter of the stabilizer bar and a second vertical distance between the upper connecting part and the plate body, wherein the first vertical distance between the upper connecting part and the extension part is smaller than the diameter of the stabilizer bar.

In the step P2, an extensible range of the extension part is determined according to a movable range of the end part of the stabilizer bar. That is, portions of the film layers that are not selected in the step P1 are removed. Consequently, the clearance spaces are formed between the extension part and the underlying plate body. Consequently, the end part of the stabilizer bar and the film layer selected in the step P1 are interfered with each other to achieve the clearance efficacy.

In the example ofFIG. 9, the selected film layer in the step P1 is the upper film layer222. In addition, a portion of the end part2042of the stabilizer bar204is clamped between the upper connecting part2112and the upper film layer222. The portions of the lower film layer223and the intermediate film layer224corresponding to the extension part2223of the upper film layer222are removed. Consequently, the region between the extension part2223of the upper film layer222and the underlying plate body212of the base plate21is hollow and defined as the clearance space23.

In the example ofFIG. 11, the selected film layer in the step P1 is the intermediate film layer224′. In addition, a portion of the end part2042′ of the stabilizer bar204′ is clamped between the upper connecting part2112′ and the intermediate film layer224′. The portions of the upper film layer222′ and the lower film layer223′ corresponding to the extension part2243′ of the intermediate film layer224′ are removed. Consequently, the end part2042′ of the stabilizer bar204′ can be placed on the extension part2243′ of the intermediate film layer224′, and the region between the extension part2243′ of the intermediate film layer224′ and the underlying plate body212′ of the base plate21is hollow and defined as the clearance space23′.