Patent ID: 12210688

DETAILED DESCRIPTION OF THE INVENTION

The invention provides a keyboard membrane30and a keyboard50with the keyboard membrane30, so that the keyboard50is waterproof.FIG.3toFIG.6show several preferred embodiments of the keyboard membrane30(30a˜30d) of the invention, and the keyboard membrane30is made with a thermoplastic wear-resistant molding membrane10(hereinafter referred to as the molding membrane) ofFIG.1.

The molding membrane10comprises: a polycarbonate polyurethane layer (or polycarbonate PU layer)20and a thermoplastic polyurethane (polyurethane elastomer) layer (or thermoplastic PU layer)22, and the two PU layers20,22are combined. The molding membrane10can be molded into a thin sheet molded object with a concave-convex structure, which can be used as the keyboard membrane30for various products such as calculators, computers, laptops, wired or wireless keyboards, remote controls, and automation equipment or mechanical equipment to become a touch-pressing molded object.

A material of the polycarbonate PU layer20is polycarbonate polyurethane, a thermoplastic polyurethane elastomer formed by polymerization of polycarbonate compounds, such as polycarbonate diols (PCDL), which has excellent physical properties and mechanical properties such as hydrolysis resistance, heat resistance, wear resistance, oxidative degradation resistance and weather resistance to be capable of withstanding a temperature of −40° C.˜80° C.

The thermoplastic PU layer22is a polyester type (Ester), polyether type (Ether) or polycarbonate type thermoplastic polyurethane, which is a polymer elastomer with excellent ductility and elasticity. Preferably, a ductility of the thermoplastic PU layer22of this embodiment still has an elastic recovery rate of no less than 98% after being stretched for 300,000 times at a stretching amount of no more than 20%. Preferably, a stretching recovery rate is not less than 99%, and has excellent recovery after stretching. The thermoplastic PU layer22is softer, more stretchable and elastic than the polycarbonate PU layer20, and is suitable for molding and shaping.

Please refer toFIG.2, the polycarbonate PU layer20and the thermoplastic PU layer22are coated on a release surface of a release layer24with a liquid PU material, and are formed by drying. The release layer24can be a release paper or release membrane. The polycarbonate PU layer20is disposed on the release surface of the release layer24, and the thermoplastic PU layer22is disposed on a surface of the polycarbonate PU layer20. Through a coating method of the applicant, problems of producing fish eyes (refer to incompletely mixed and refined crystals of PU particles in a manufacturing process of extrusion or injection of PU membrane, commonly known as crystal dots) and producing bubbles by the conventional coating method can be avoided in the molding membrane10to be capable of producing the thin molding membrane10with small tolerance and uniform texture precisely, so that a thickness T is less than 0.1 mm, which is between 0.03 mm and 0.1 mm, preferably, a thickness of the molding membrane10is 0.03 mm˜0.07 mm, most preferably, the thickness T ranges from 0.05 mm˜0.06 mm, and a hardness thereof is below 85 D (inclusive) of Rockwell hardness, and has flexibility. The molding membrane10is light, thin, soft, easy to shape, and has excellent elasticity, ductility and wear resistance. In this embodiment, a thickness of the polycarbonate PU layer20is 0.04 mm or 0.05 mm, and a thickness of the thermoplastic PU layer22is 0.02 mm or 0.03 mm. The release surface of the release layer24can be patterned or matte treated, so that an outer surface of the polycarbonate PU layer20can be patterned or matted.

When the molding membrane10is to be thermoplastically molded, the molding membrane10can be molded without peeling off the release layer24or in a state where the release layer24is peeled off. If molding is carried out in a state where the release layer24is not peeled off, the release layer24is torn off after the molding membrane10is finished with molding.

With a moldability of the thermoplastic PU layer22, the molding membrane10can be molded into thin sheet molded objects of various shapes by a mold, to be used as touchable molded objects for users to press and touch, for example, being used as touchable outer layers of various electronic devices, such as but not limited to, keyboard membranes of remote controls, notebook computers, mobile phones, monitors, etc. The four types of keyboard membranes30(30ato30d) shown inFIGS.3to6can be used in electronic devices or machines with physical keys or buttons, for example, for using in keys or buttons of notebook computers, keyboards, remote controls, and mechanical operation panels.

The molding membrane10is thermoplastically molded into the keyboard membranes30of various dimensions and sizes in a mold at a temperature of 100˜250° C., for example, molding is performed in the mold by suction. Each of the keyboard membranes30can be molded with a plurality of concave-convex parts as required, as shown inFIG.3toFIG.8. The concave-convex part comprises a plurality of upwardly protruding pressing parts32, corresponding to a plurality of keys42of a key module40, and each of the keys42has a keycap44and a key foot45. Please refer toFIG.4, the concave-convex part further comprises a larger concave touch area33, which corresponds to a touch pad of an electronic device or a notebook computer. The molding membrane10is thin enough to enable the keyboard membranes30to form the touch area33.

Please refer toFIG.3toFIG.6, front, rear, left and right peripheries of the keyboard membrane30of the invention are further provided with a peripheral edge31extending outward from the pressing parts32, and the peripheral edge31can be used to wrap other parts other than the keys42of the key module40, as shown inFIGS.3A and4A. The peripheral edge31of the keyboard membrane30wraps a periphery of the key module40and wraps a bottom surface of the key module40downwards, so that parts other than the keys42can also be waterproof and dustproof. After the keyboard membrane30wraps the key module40, the waterproof and dustproof keyboard50(50a,50b) is formed as a whole. The polycarbonate PU layer20is a surface layer of the keyboard membrane30, and the thermoplastic PU layer22is an inner layer of the keyboard membrane30. When a user presses the keys42, the polycarbonate PU layer20is contacted.

Each of the pressing parts32has a rectangular or other geometrically shaped top wall34and a peripheral wall35extending downward from a periphery of the top wall34. As shown inFIGS.7,8, and10, the top wall34is located perpendicular to the peripheral wall35and defines an intersection angle341and has a flat edge located between the top wall34and the peripheral wall35. As shown inFIG.5andFIG.8, one character36or a plurality of characters36is/are engraved on the top wall34of each of the pressing parts32by laser, and the different characters36are engraved on the different pressing parts32. The characters36engraved by laser are formed by removing a material of the polycarbonate PU layer20, and a depth of engraving reaches the thermoplastic PU layer22, so each of the characters36forms a hollow part38penetrating the polycarbonate PU layer20on the top wall34, as shown inFIG.8, and the thermoplastic PU layer22is exposed at the hollow part38.

The polycarbonate PU layer20and the thermoplastic PU layer22have different colors, for example, the polycarbonate PU layer20has a dark color, while the thermoplastic PU layer22has a light color, and vice versa. Therefore, a color of the character36is a color of the thermoplastic PU layer22, which can be clearly displayed on the pressing part32. The thermoplastic PU layer22can be a color layer, which can be formed by mixing colorants or pigments to display various colors and become a color of the character36.

The keyboard membrane30after laser engraving, as shown inFIG.8, is installed on the key module40of an electronic device or a mechanical equipment, and the peripheral edge31of the keyboard membrane30wraps the key module40. Each of the pressing parts32corresponds to one of the keys42, and an inner surface of the pressing part32is bonded to the keycap44of the key42by a hot melt adhesive or a glue. For example, the hot melt adhesive is pasted on a top surface of the keycap44to bond the pressing part32to the keycap44, and each of the keys42can be pressed from each of the pressing parts32. The polycarbonate PU layer20is a surface layer of the keyboard membrane30, which makes a surface of the keyboard membrane30wear-resistant, free from hand marks, difficult for dirt to stick on the keyboard membrane30, and not sticky. Preferably, the pressing part32is bonded to the keycap44only by an inner surface of the top wall34, and the peripheral wall35of the pressing part32is not in contact with the hot melt adhesive, so that physical properties of the peripheral wall35will not be affected by the hot melt adhesive. The key module40described above is not a main object of the invention, so it will not be described in detail.

The thermoplastic PU layer22can not only be made to have different colors, but also can be made transparent or translucent to have transmittancy, so that the key module40can use backlight technology to enable LED light to penetrate through the hollow part38to make the character36glow.

A thermoplastic wear-resistant molding membrane10′ ofFIG.9can be thermoplastically made into the keyboard membrane30(30e) ofFIG.10in a mold, the molding membrane10′ has the polycarbonate PU layer20, the thermoplastic PU layer22, and further comprises: an intermediate polyurethane layer (or intermediate PU layer)21. The polycarbonate PU layer20and the thermoplastic PU layer22are the same as those of the first preferred embodiment, which can be understood from that embodiment.

The intermediate PU layer21in this embodiment is also a polycarbonate PU, which is the same as the polycarbonate PU layer20, but not limited thereto, and other types of thermoplastic PU can be used.

The polycarbonate PU layer20, the intermediate PU layer21and the thermoplastic PU layer22are sequentially coated with a liquid PU material on the release layer24and formed by drying. The polycarbonate PU layer20is disposed on the release surface of the release layer24, the intermediate PU layer21is disposed on a surface of the polycarbonate PU layer20, and the thermoplastic PU layer22is disposed on a surface of the intermediate PU layer21. The applicant is capable of precisely manufacturing the thin molding membrane10′ with small tolerance and uniformity by a coating method, and there are no fish eyes (crystal dots) and air bubbles inside the molding membrane10′. The thickness T of the molding membrane10′ ranges from 0.04 mm to 0.1 mm, preferably mm to 0.09 mm. The thickness T formed by the three PU layers20,21and22of this embodiment is preferably below 0.04 mm˜0.08 mm (inclusive), most preferably, the thickness T is between 0.05 mm and 0.07 mm, and a hardness of the molding membrane is below 85 D of Rockwell hardness. The molding membrane10′ is light, soft, and has excellent elasticity, ductility and wear resistance. In this embodiment, the polycarbonate PU layer20has a thickness of 0.03 mm, the intermediate PU layer21has a thickness of mm, and the thermoplastic PU layer22has a thickness of 0.02 mm. The polycarbonate PU layer20and the thermoplastic PU layer22are made to have contrasting colors of dark and light colors; and the intermediate PU layer21is transparent or translucent.

When the molding membrane10′ is thermoplastically molded, it can be molded under a state of peeling off or not peeling off the release layer24in order to be molded into the keyboard membrane30with desired shape and contour. A thickness of the keyboard membrane30is T, and a hardness thereof is below 85 D of Rockwell hardness.

FIG.10shows that the molding membrane10′ ofFIG.9is thermoplastically molded into the keyboard membrane30(30e) in a mold, and combined with the key module40to form the waterproof and dustproof keyboard50, the keyboard membrane has the concave-convex parts, comprising the upwardly protruding pressing parts32, and an inner surface of each of the pressing parts32is bonded with the keycap44of the key42of the key module40. The polycarbonate PU layer20is a surface layer of the keyboard membrane30(30e), the thermoplastic PU layer22is an inner layer of the keyboard membrane30(30e), and the intermediate PU layer21is located between the polycarbonate PU layer20and the thermoplastic PU layer22. The polycarbonate PU layer is touched by the user when operating keys or buttons of an electronic device. The intermediate PU layer21is made into a transparent or translucent layer to enable light to penetrate, or the intermediate PU layer21can be made into an opaque layer.

Each of the pressing parts32has the top wall34and the upright peripheral wall the character36or the characters36is/are engraved on the top wall34by laser, so that the top wall34forms a hollow part38′ that penetrates the polycarbonate PU layer20. Laser engraving is used to remove a material of the polycarbonate PU layer20, a depth of laser engraving (that is, a depth of the hollow part38′) is capable of reaching the polycarbonate PU layer20or even reaching the intermediate PU layer21. The intermediate PU layer21is capable of protecting the thermoplastic PU layer22during laser engraving. If the intermediate PU layer21is transparent or translucent, even if a material of the intermediate PU layer21is not removed or only partially removed, a color of the thermoplastic PU layer22can still be exposed in the hollow part38′, making the characters36of the pressing parts32have colors. When a backlight module of the key module40emits light, the light is capable of penetrating the intermediate PU layer21and passing through the hollow part38′, so that the characters36of the pressing parts32are capable of emitting light.

The keyboard membrane30of the invention has the following efficacies.

The keyboard membrane30is molded and shaped in one piece, which is dustproof and waterproof. The keyboard membrane30wraps the keys42and wraps a periphery and a bottom surface of the key module40by the peripheral edge31, so that the keyboard membrane30and the key module40form the waterproof and dustproof keyboard50, preventing dirt, liquid, and moisture from entering the keyboard50. Thus a keyboard of an electronic device or an independent keyboard, such as notebook computers and keyboards used by special forces for military purposes, is still waterproof even when wading in water in order to maintain usability.

A surface layer of the keyboard membrane30is formed by the polycarbonate PU layer20, which has a property of wear resistance and can be used for a long period of time without wear. The polycarbonate PU layer20is subjected to a wear resistance test with a soft rubber weighing 350 grams, and is capable of withstanding more than 15,000 times of friction without breaking.

Physical and chemical properties of the polycarbonate PU layer20are stable, a surface of the keyboard membrane30is stable, does not change, is not easy to get dirty, and is not sticky, and a tactile impression of fingers on surface layers of the pressing parts32(that is, the polycarbonate PU layer20) is fresh and clean and not sticky. Moreover, the polycarbonate PU layer20is weather-resistant, and a usability thereof will not be affected in extreme weather environments.

The keyboard membrane30is extremely thin (not more than 0.1 mm), soft and has excellent ductility, and can be precisely thermoplastically molded, and an intersection angle341or a bending position between a junction of the top wall34and the peripheral wall35of the pressing part32can be precisely, completely and beautifully molded and shaped. A ductility of the thermoplastic PU layer22is excellent, and can be stretched to more than twice a length, so the molding membrane10is capable of meeting particularly large demands for ductility at angles of the molded object, and the intersection angle341or a bending position of the keyboard membrane30can be molded and shaped smoothly without breaking.

The keyboard membrane30of the invention is formed of at least two PU layers of two different materials, is thin and soft, and the thermoplastic PU layer22provides excellent elasticity. The shaped keyboard membrane30is also thin and has excellent elasticity. When the pressing part32is pressed, the peripheral wall35can be easily deformed, flexed and elastically recovered. A keystroke (press-recover) of tapping the pressing part21and the key42is clear, providing excellent tactile impression and handfeel of tapping. Since the keyboard membrane30is thin and soft, the user only needs to press the key42effortlessly. The keyboard membrane30has an excellent stretching recovery rate, so that the pressing part32has an excellent recovery after being tapped. According to the applicant's experiment, the pressing part32has an elastic recovery rate of 99% after being tapped tens of thousands of times.

Furthermore, the keyboard membrane30is thin, soft and has excellent elasticity, and the adjacent pressing parts32will not pull against one another, so the user can easily tap the keyboard50.

A keystroke of tapping the pressing part21of the keyboard membrane30is stable and reliable, even after a long period of use, and invalid keystroke will not occur.

The molding membrane10has no fish eyes and air bubbles, and there will be no crystal dots and air holes in the molded keyboard membrane30. When a light of a backlight module passes through the characters36, the light will not be refracted or scattered, and will not cause consumers to consider the keyboard membrane to be a defective product.

The molding membrane10is thin and uniform, and a manufacturing tolerance thereof is small, a tolerance of thickness can be 0.005 mm˜0.01 mm, such as 0.025 mm, so that the keyboard membrane30of the invention with a thickness of less than 0.1 mm can be precisely engraved by laser.

The keyboard membrane30is engraved by laser from the front polycarbonate PU layer20toward an inner direction, and laser engraving operation is simple and easy to implement.

The thermoplastic PU layer22is used as a color layer, which can be toned into different colors to make the characters36have different colors. The thermoplastic PU layer22of this embodiment is made white with white pigments, such as titanium white or calcium carbonate, while the polycarbonate PU layer20is made black, so the two PU layers20,22form contrasting colors of light color and dark color, making the characters36distinct. In addition, the molding membrane10can be added with graphene to make the keyboard membrane30conductive electrically.

Although the invention has been disclosed as above with the embodiments, it is not intended to limit the invention. A person having ordinary skill in the art to which the invention pertains can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, scope of protection of the invention shall be subject to what is defined in the pending claims.