Key structure

A key structure has a support member that reduces manufacturing costs, assembly costs, and the total height of the manufactured product. The support member is mounted between a base and a key cap. The support member has a first frame and a second frame, which are both formed in a united manner by injection. The first frame has a base portion and a pair of side arms connected with the base. The side arms both have a penetrated transverse pivotal hole formed therein. The second frame is disposed between the side arms and has a pair of pivots protruded respectively from two sides thereof. The pivots are formed and mounted directly in the pivotal holes during ejection molding, and an annular channel is formed for receiving a tubular mold during ejection molding.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a key structure, particularly to a key structure having a scissor-like linkage structure which is adapted for an electronic product with keys, such as a notebook computer, a computer keyboard, a telephone, a printer or a multi-function printer, for controlling key strokes.

2. Description of the Prior Art

Keyboards are widely used with various devices, such as computers, and notebooks, to input characters and numerals. Especially concerning notebooks, space is limited and the keyboard structure is particularly important. To make a key on the keyboard easy to depress, the key is usually designed with a scissors-like linkage structure (often called a support member) to function no matter where force is exerted on the key cap. In other words, even though the force is exerted on the edge of the key cap, the force is generally equally distributed over the entire surface of the key cap by the scissors-like linkage structure. Furthermore, while space is an especially important consideration in designing keyboards for portable computing devices, key switches with scissors-like linkage structure are often the solution.

Please refer toFIG. 1, which illustrates a perspective explored view of a key structure according to the prior art. The key structure has a key cap90, a scissors-like linkage structure consisting of a first frame91and a second frame92, and a base93. The bottom ends of the first frame91and the second frame92are formed with pivots94,95respectively for connecting pivotally with pivotal seats96,97on the base93. The top ends of the first frame91and the second frame92connect pivotally to the bottom surface of the key cap90.

The first frame91and the second frame92are often formed by the injection molding technique. Connection mechanisms are provided on the middle portion of the first and second frames, so that the first and second frames are rotatably connected with each other to form the scissors-like linkage structure. However, in the conventional connection mechanism, the first frame and the second frame must be respectively formed on two independent areas during the injection molding process. Therefore, the necessary area for forming the scissors-like linkage structure is relatively large, resulting in an increase in manufacturing costs and the complication of the assembly of the inner and outer arms.

During the assembly of the scissors-like linkage structure, a step of separating the first frame and the second frame is performed first. Then, the two independent frames are sophisticatedly connected through the connection mechanism to form the scissors-like linkage structure. Therefore, the assembly process is relatively complicated and time-consuming, which induces the high assembly costs.

For solving the above-mentioned disadvantages, U.S. Pat. No. 6,706,986 published on Mar. 16, 2004 provides a scissors-like linkage structure for reducing injection molding costs and assembly costs. Please refer toFIG. 2, which shows a scissors-like linkage structure70applied in a key structure60for connecting a key cap62to a base64of the prior art. The scissors-like linkage structure70has a first frame72and a second frame74. Each of the side arms of the second frame74are formed with a first hole742and a second hole744connecting to each other. Please refer toFIGS. 3A and 3B, which respectively illustrate a side view and a top view of the conventional scissors-like linkage structure. The scissors-like linkage structure is formed in a united manner by the injection molding technique. After injection, two pivots720of the first frame72are positioned in the first holes742of the second frame74and are moved along the radial direction. A space700is formed between the first frame72and the second frame74, so that the second frame74can move in the first frame72. The next step is moving the pivots720so that they hook into the second hole744and unite together. However, unavoidably, the scissors-like linkage structure of this prior art still needs one labor assembly step, which is pushing the pivots720of the first frame72into the second holes744of the second frame74. Such step not only raises labor costs, but also increases the possibility of damage caused by improper assembly.

Moreover, the above mentioned scissors-like linkage structure70requires that the first hole742that is bigger than that of before, so that it increases the total height of the key structure and the height of the electronic device. It is therefore poorly designed for notebook computer keyboards.

Furthermore, the assembly action of the scissors-like linkage structure70pushing the first frame72into the second frame74results in a lateral force being applied to the pivots720of the first frame72. The lateral force may cause the pivots720to break and raises the possibility of the product breaking down.

Besides, the scissors-like linkage structure70has the space700formed between first frame72and the second frame74let the second frame74move, so that the area of the mold of the scissors-like linkage structure70needs to be larger than the area of a mold of a single frame.

The inventor, after investigation and research, thus provides the present invention of logical design for reducing injection costs and reducing the number of assembly steps to overcome the above-mentioned imperfections.

SUMMARY OF THE INVENTION

The present invention provides a key structure having a scissor-like linkage structure that can reduce injection costs, reduce assembly costs, and lower the total height of a manufactured product. It applies single injection technology that form pivots directly in the pivotal holes of the scissor-like linkage structure. The present invention not only reduces the injection molding area, thereby reducing injection costs, but also avoids assembly steps completely. The present invention can save labor assembly costs, and avoid the possibility of product assembly failure.

The present invention provides a key structure comprising a base, a support member, and a key cap. The support member is connected with the base. The support member is formed in a united manner, and comprises a first frame and a second frame. The first frame has a base portion and a pair of side arms respectively connecting with two sides of the base portion. Each of the side arms has a transverse-through pivotal hole formed therein. The second frame is positioned between the side arms and has a pair of pivots protruding from two sides thereof. The pair of pivots are formed in the pivotal holes respectively. The key cap is mounted above the support member and connected to the support member.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Please refer toFIG. 4, which illustrates an exploded perspective view of a key structure of the preferred embodiment according to the present invention. The present invention provides a key structure1comprising a base10, a support member20and a key cap30. The support member20is removably connected with the base10. The key cap30is mounted above the support member20and connected to the support member.

The base10is formed with a front hook12and two rear hooks14for connecting pivotally with the support member20.

Please refer toFIGS. 5 and 6, which respectively illustrate a top view and a side view of a support member of the key structure according to the present invention. The support member20comprises a first frame21and a second frame22, which are formed by integral injection and are incorporated together during manufacturing procedure. In other words, there is no need to manufacture the first frame21and the second frame22separately and to have an additional process of assembly of the first frame21and the second frame22with each other. The first frame21has a base portion23and a pair of side arms25extending from each end of the base portion23, respectively. Each of the side arms25has a transverse-through pivotal hole250formed therein. The second frame22is positioned between the side arms25and has a pair of pivots220protruding from each side thereof. The pivots220are formed to be within the pivotal holes250respectively, and a pair of annular channels251the pivotal holes250around the pivots220, wherein the annular channels251are respectively received with a tubular mold during the injection shaping.

The support member20of the present invention has the advantage of being shaped once by injection. In other words, the support member20is assembled immediately after injecting the melted material into a single mold, i.e. the first frame21and the second frame22are formed directly in an assembled condition so that no assembly is required. Therefore, labor costs are reduced.

The mold of the support member20consists of upper and lower molds and two lateral tubular molds. The second frame22is disposed in the first frame21with an interval and without an overlapping portion. The upper and lower molds clip together to form a first frame cavity at an outer periphery, a second frame cavity at an inner side, and a pair of outward circle molding holes formed on two sides of the upper and lower molds. A pair of pivot root channels are formed between the first frame cavity and the second frame cavity. Each of the circle molding holes is received with a thin tubular mold, which extends to the inner edges of the first frame cavity. A hollow portion of the thin tubular mold connects tightly with the pivot root channel. Next, melted material is injected through injection holes of the upper mold, and expels the air in the mold cavity via exhaust holes. After injecting the material, the solid portion of the tubular mold forms the annular channel251; the hollow portion of the tubular mold and the pivot root channel form the pivot220. After it has cooled down, the tubular molds are drawn out from the two sides and separated the upper and lower molds.

The pivot220of the support member20has a thicker root adjacent to the second frame22, i.e., the pivot220has a portion, which is located within the pivotal hole250, with a diameter smaller than that of the remainder of the pivot220outside the pivotal hole250.

The first frame21comprises a pair of front shafts252and a pair of rear shafts254which are respectively formed on the opposited ends of the side arms25. The front shafts252are adjacent to the base portion23, and the rear shafts254are positioned on ends of the side arms25. The front shafts252are pivotally connecting to the bottom of the key cap30, and the rear shafts254are pivotally connected to the rear hooks14of the base10.

The second frame22comprises a central port226, a transverse shaft222and a pair of shafts224. The transverse shaft222is aligned with the front shafts252of the first frame21, and the shafts224are aligned with the rear shafts254of the first frame21. The transverse shaft222is pivotally connected to the front hook12of the base10, and the shafts224are pivotally connected to the bottom of the key cap30.

The base portion23of the first frame21is formed with an outward oblique surface232. The oblique surface232is against a bottom surface of the key cap30, when the support member20is raised in a crisscross manner (usually by an elastic dome). Therefore, the oblique surface232has the functions of stopping and positioning. In other words, when the support member20is raised to a predetermined position, the oblique surface232props up the bottom surface of the key cap30and stops the support member20from continuing to rise.

A central portion of the side arms25of the first frame21has a width being substantially equal to that of a bottom surface of the key cap30. Each of the side arms25are formed with an outward oblique surface258on the central portion thereof. The oblique surfaces258of the side arms25are forced against two sides of the bottom surface of the key cap30, when the key cap30is depressed. Therefore, the key cap30is supported better when it is depressed to the end, and performs better.

In this embodiment, the first frame21further has a pair of stopping blocks256which extend inwardly from ends of the side arms25respectively. The base10is formed with a pair of stoppers16corresponding to the pair of stopping blocks256. The stopping blocks256are forced against the stoppers16when the key cap30is depressed. The stoppers16hold and stop the stopping blocks256in place when a key is depressed. The stoppers16stop the key from wavering or rotating and ensure equilibrium when a key is depressed, so that the stability and balance of the key are enhanced.

Please refer toFIG. 7, which illustrates a top view of a support member of the key structure of the second embodiment according to the present invention. The different sized key needs a different sized support member. By applying the character of integral injection to the present invention, support members of different sizes are possible. Therefore, the shape of the present invention is not limited by the above embodiments. The second embodiment provides a support member20a, which comprises a first frame21aand a second frame22a. The first frame21ahas a base portion23aand a pair of side arms25aconnected with two sides of the base portion23a. Each of the side arms25ahas a transverse-through pivotal hole250aformed therein. The second frame22ais positioned between the side arms25aand has a pair of pivots220aprotruding from two sides thereof. The pair of pivots220aare mounted in the pivotal holes250arespectively and form an annular channel around the pivots220a. The first frame21acomprises a pair of front shafts252a, a pair of rear shafts254a, which are respectively formed on two sides of the side arms25a, and a pair of stopping blocks256aprotruding from the inner sides of the side arms25a. The second frame22acomprises a central port226a, a transverse shaft222aand a pair of shafts224a.

A summary of the characteristics and advantages of the present invention is as follows:

1. The support member (or called scissors-like linkage structure) is formed in a united manner by integral injection technology. The second frame is pivotally connected to the first frame directly. The present invention does not need labor for separating frames and assembling. It simplifies the assembly processes and saves time and labor, thereby reducing labor costs.

2. The present invention reduces the mold area of injection, and is almost equal to one frame, thereby saving on mold costs and reducing the occupied space effectively.

3. The support member is formed compactly, which controls the total height to about the height of the pivotal hole, and does not increase the total height, therefore, it is beneficial for the development of notebook computers.

4. The oblique surfaces258are forced against the bottom surface of the key cap30after the key cap is depressed, and the oblique surface232is forced against the bottom surface of the key cap30when the support member20rises. The support member20ensures a smoother feeling when typing.