User-interface assembly and method for integrating touch assembly into user-interface assembly

A user-interface assembly disclosed herein comprises: a supporting frame; a part for providing a switch function to the user-interface assembly and to be received in a recess formed in the supporting frame; and an overlay for covering and adhering to an upper surface of the supporting frame and an upper surface of the part by a back adhesive when the part is received in the recess; wherein a transition zone is provided around the part under the overlay, which transition zone extends at least from a sidewall of the recess toward the part such that the overlay can smoothly transit from the upper surface of the supporting frame to the upper surface of the part. Also disclosed herein is a corresponding method for integrating a touch assembly into a user-interface assembly. A flat design of a user-interface assembly can be achieved in a cost effective manner.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is the national stage entry of International Patent Application No. PCT/CN2017/081596, filed on Apr. 24, 2017.

TECHNICAL FIELD

The present disclosure relates to a user-interface assembly and a method for integrating a touch assembly into a user-interface assembly.

BACKGROUND ART

A touch screen and a membrane switch are usually incorporated into electrical systems as user input devices. They are usually integrated with a supporting frame or an enclosure part to form a user-interface assembly of an electrical system. For cosmetic demanding applications or other demanding applications like requirement of water or dust proof, seamless and flat design is required for an outer surface of the user interface assembly.

The seamless design is generally achieved by adhesively laminating a flexible cover sheet or overlay onto the entire outer surface of the user-interface assembly. Because of manufacturing tolerances of thickness dimensions of the touch screen and the membrane switch, as well as tolerances of corresponding dimensions of the supporting frame, there is always a challenge when trying to achieve a visually flat appearance of the overlay covering the touch screen, the membrane switch, and the supporting frame. More specifically, the challenge to achieve a visually flat appearance of the overlay comes from the mismatched dimensions (height difference) between the touch screen and the corresponding recess on the supporting frame, and the mismatched dimensions between the membrane switch and the corresponding recess on the supporting frame.

FIG. 1shows a partial sectional view of a portion of the user-interface assembly according to the prior art. As shown inFIG. 1, the user-interface assembly has a visually unflat appearance.

One approach known to the person skilled in the art is to control the tolerance of each part to a smallest level. However, strict tolerance control inevitably increases the manufacturing cost.

Another known approach to integrate the touch screen and switch keys providing a flat design is to etch circuits of the switch onto the indium tin oxide (ITO) layer of the touch screen. It eliminates layers of membrane switch and thus avoids the unflatness caused by the mismatched dimensions between the membrane switch and the supporting frame. However, the special process of etching customized switch circuits onto the touch screen is considerably expensive compared to the commonly used membrane switch. Moreover, the unflatness caused by the mismatched dimensions between the touch screen and the supporting frame is still not resolved.

SUMMARY OF THE DISCLOSURE

In view of the problems existing in the prior art, an object of the present disclosure is to provide a user-interface assembly and a method for integrating a touch assembly into a user-interface assembly.

For achieving this object, in one aspect, provided is a user-interface assembly, comprising: a supporting frame; a part for providing a switch function to the user-interface assembly and to be received in a recess formed in the supporting frame; and an overlay for covering and adhering to an upper surface of the supporting frame and an upper surface of the part by a back adhesive when the part is received in the recess; wherein a transition zone is provided around the part under the overlay, which transition zone extends at least from a sidewall of the recess toward the part such that the overlay can smoothly transit from the upper surface of the supporting frame to the upper surface of the part.

According to an optional embodiment, the transition zone is achieved at least by forming an adhesive-free zone such that the overlay can not be adhered to a portion of the upper surface of the supporting frame and/or a portion of the upper surface of the part in the transition zone.

According to an optional embodiment, the transition zone is achieved at least by a flexible portion of a top layer of the part extending outward from a body of the part, wherein the flexible portion has a smaller thickness than a thickness of the body.

According to an optional embodiment, the adhesive-free zone is formed by removing a corresponding portion of the back adhesive.

According to an optional embodiment, in an assembled state, the back adhesive is adhered to the flexible portion; and/or the part is formed by laminating a serial of individual layers.

According to an optional embodiment, a thickness of a thickest portion of the part can be equal to, bigger or smaller than a depth of the recess.

According to an optional embodiment, the user-interface assembly further comprises a touch screen which is received in an additional recess formed in the supporting frame.

According to an optional embodiment, the part is a hard printed circuit board.

According to an optional embodiment, the part is a membrane switch.

In another aspect, provided is a method for integrating a touch assembly into a user-interface assembly, the touch assembly having a top surface and a bottom surface, the user-interface assembly having a supporting frame and a recess for receiving the touch assembly, and the method comprising: placing the top surface of the touch assembly on a flat table; positioning the supporting frame at a predetermined position relative to the touch assembly such that at least one portion of the touch assembly is located within the recess; and injecting a flowable adhesive into a gap between the portion of the touch assembly and a corresponding portion of the recess from a direction of a bottom of the supporting frame to fix the touch assembly onto the supporting frame, so that an amount of the injected flowable adhesive can be adapted according to a different volume of the gap.

According to an optional embodiment, the touch assembly integrates a touch screen and an overlay covering and adhering to the touch screen.

According to an optional embodiment, positioning the supporting frame comprises: placing and adhering a top surface of the supporting frame onto a portion of the overlay extending out of the touch screen; and/or before injecting the flowable adhesive, placing a weight body onto a backside of the touch screen.

According to an optional embodiment, the flowable adhesive is injected into the gap via injection ports formed in the supporting frame.

According to an optional embodiment, the injection ports have round shapes or slot shapes.

According to the present disclosure, a flat design of a user-interface assembly can be achieved in a cost effective manner.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Some exemplary embodiments of the present disclosure will be described hereinafter in more details with reference to the drawings to better understand the basic concept of the present disclosure.

FIG. 2shows an exploded sectional view of a user-interface assembly having seamless design, according to the first exemplary embodiment of the present disclosure.

As shown inFIG. 2, the user-interface assembly mainly comprises a supporting frame1, a part2and a touch assembly3. It shall be noted that the part2is normally but not limited to an apparatus for providing a switch function to the user-interface assembly, which could be a flexible component like a membrane switch or a hard device like a printed circuit board in the first embodiment. To simplify the following description, a membrane switch is taken as an example in the first embodiment. The touch assembly3mainly comprises a touch screen4, an overlay5larger than the touch screen4, an optical clear adhesive6disposed between the touch screen4and the overlay5and used for adhering the overlay5to the touch screen4, a first back adhesive7disposed on a backside of the touch screen4and used for adhering the touch screen4to the supporting frame1, and a second back adhesive8disposed on a backside of a portion of the overlay5extending beyond the touch screen4and used for adhering the portion of the overlay5to the supporting frame1and the membrane switch2.

The overlay5is usually a flexible polyester film having a thickness ranging from 0.1 mm to 0.3 mm, such as of 0.13 mm, 0.18 mm, or 0.25 mm.

Also can be seen fromFIG. 2, a first recess9is formed in the supporting frame1for receiving the membrane switch2and a second recess10is formed in the supporting frame1for receiving the touch screen4. A thickness of the membrane switch2is shown as Dm, while a depth of the first recess9is shown as Dfm. A distance between a bottom of the first back adhesive7and a bottom of the second back adhesive8is shown as Dt, while a depth of the second recess10is shown as Dft. Ideally, Dm and Dt should be nominally equal to Dfm and Dft respectively, to achieve a completely flat appearance on an outer surface of the overlay5.

However, during manufacturing process, these dimensions Dm, Dfm, Dt and Dft have respective tolerances. As known by the person skilled in the art, a tolerance for Dm, Dfm or Dft may be +/−0.1 mm, +/−0.15 mm, or +/−0.2 mm, and a tolerance for Dt may be +/−0.15 mm, +/−0.2 mm, +/−0.25 mm, +/−0.3 mm, or +/−0.4 mm. If these dimensions are not matched properly, the overlay5may have visually unflat appearance, in particular at sidewalls defining the first recess9and the second recess10.

To achieve visually flat appearance of the overlay5at the membrane switch2, as shown inFIG. 2, an adhesive-free transition zone11is provided above the membrane switch2adjacent to the sidewall of the first recess9, preferably along the entire sidewall of the first recess9.

FIG. 3shows a partial sectional view of a portion of the user-interface assembly in an assembled state. As shown inFIG. 3, the adhesive-free transition zone11is embodied as a cutout, preferably an annular cutout along the entire sidewall of the first recess9.

An outer periphery of the adhesive-free transition zone11is preferably aligned with the sidewall of the first recess9. According to another optional embodiment of the present disclosure, the adhesive-free transition zone11is formed across the sidewall of the first recess9so as to extend outward beyond the first recess9. A width of the adhesive-free transition zone11may be selected based on a desired flatness on the outer surface of the overlay5. The width of the adhesive-free transition zone11may be set to be 3 mm, 3.5 mm, 4 mm, 4.5 mm or other non-limiting values.

For the embodiment shown inFIG. 3, a tolerance zone12for the thickness Dm of the membrane switch2and a tolerance zone13for the depth Dfm of the first recess9may preferably be selected as shown inFIG. 4, wherein the thickness Dm of the membrane switch2and the depth Dfm of the first recess9have the same nominal value14and the tolerance zone13for the depth Dfm is above the tolerance zone12for the thickness Dm, which means that the depth Dfm of the first recess9is at least equal to the thickness Dm of the membrane switch2. With this tolerance zone setting, the assembled state as shown inFIG. 3may be achieved. During assembling, the membrane switch2is firstly placed into and adhered to the first recess9by a bottom adhesive layer (not shown separately) of the membrane switch2. Then, the overlay5with the second back adhesive8is adhered onto the supporting frame1and the membrane switch2. The adhesive-free transition zone11allows the overlay5to smoothly transit from the supporting frame1to the membrane switch2, thus making the unflatness of the overlay5visually imperceptible.

Because the second back adhesive8has a certain thickness, the membrane switch2and the first recess9also may use other tolerance zone settings, as long as the tolerance zone settings can ensure that the thickness of the membrane switch2is at most equal to the sum of the depth of the first recess9and the thickness of the second back adhesive8.

FIG. 5shows a partial sectional view of a portion of the user-interface assembly in an assembled state, according to the second exemplary embodiment of the present disclosure.

In the second embodiment, it would be better to assemble a flexible component to perform the switch function as shown inFIG. 5. A membrane switch21is formed such that a flexible portion22extends outward from and in flush with a top of a body23of the membrane switch21. The flexible portion22has a smaller thickness than the body23. The flexible portion22preferably extends along the entire periphery of the body23so as to form a ring shape, as shown inFIG. 6which shows a sectional view of the membrane switch21. In the embodiment, the flexible portion22may form a transition zone24and a corresponding portion of the touch assembly has a back adhesive25.

According to one exemplary embodiment of the present disclosure, the membrane switch21may be formed by laminating a serial of individual layers. For example, the layers from top to bottom may comprise a graphic layer as a top layer, an electro-static discharge (ESD) layer, a spacer layer, one or more circuit layers and a bottom adhesive layer. According to one exemplary embodiment of the present disclosure, the top layer of the membrane switch21is a flexible polyester layer with or without ESD shielding capability and therefore the top layer may be extended intentionally to create the transition zone. That is to say, a portion of the top layer acts as the flexible portion22.

The flexible portion22may extend to the sidewall of the first recess9or be spaced from the sidewall by a distance. A width of the transition zone24is measured from the sidewall to the body23, as shown inFIG. 5. The width of the transition zone24preferably may be set to be 3 mm, 3.5 mm, 4 mm, 4.5 mm or other non-limiting values.

In this case as shown inFIG. 5, a thickness of the membrane switch21is smaller than the depth of the first recess9.

FIG. 7shows another case based on the same concept as inFIG. 5in a partial sectional view. However, in this case as shown inFIG. 7, the thickness of the membrane switch21is larger than the depth of the first recess9.

In either case, the back adhesive25may keep continuously in the transition zone24and is adhered to the top layer of the membrane switch21without the need of being cut out as inFIG. 3. Because of the flexibility of the top layer of the membrane switch21in the transition zone24, and also because of the absence of the bottom adhesive layer of the membrane switch21in the transition zone24, the overlay5may smoothly transit from the supporting frame1to the membrane switch21, thus making the unflatness of the overlay5visually imperceptible.

It should be noted that the flexible portion22even may be omitted such that the back adhesive25extends across a gap formed between the sidewall of the first recess and the membrane switch.

For the cases as shown inFIG. 5andFIG. 7, as shown inFIG. 8, the tolerance zone13for the depth of the first recess and the tolerance zone12for the thickness of the membrane switch preferably may be set symmetrically along the nominal value14.

These embodiments described above are based on the same technical concept that a transition zone is created for example by forming a cavity under the overlay, which transition zone at least extends to the sidewall of the first recess such that the overlay can smoothly transit from the supporting frame to the membrane switch rather than change abruptly at the sidewall.

Of course, the technical concept also may be applied to transition at the sidewall of the second recess.

However, the touch assembly3is usually provided as a pre-assembled structure such that it is hard to apply the above technical concept. In this case, a method for integrating the touch assembly3into the user-interface assembly is provided, which method can achieve a flat appearance on the outer surface of the overlay5. The method uses a thickness adjustable adhesion technique to achieve a flat appearance.

Specifically, as shown inFIG. 9, the touch assembly3(with the second back adhesive8on its overlay5) is firstly placed upside down on a flat table26. Then the supporting frame1is aligned, placed and adhered onto the overlay5of the touch assembly3via the second back adhesive8. At this time, the touch screen4can still be moved up and down within the second recess of the supporting frame1due to the flexibility of the overlay5. The assembling process continues by placing a weight body27onto the backside of the touch screen4. The overlay5of the touch assembly3is now flatly mating with the flat table26under the pressure of the weight body27. A flowable adhesive28is then injected into a gap between the backside of the touch screen4and a bottom of the second recess through injection ports29formed in the supporting frame1by any kind of adhesive injection tools30.

In this case, the depth of the second recess should be larger than a distance between the backside of the touch screen4and the bottom of the second back adhesive8.

It should be noted that although the membrane switch and the first recess are not shown inFIG. 9, they also may be incorporated into the user-interface assembly.

FIG. 10shows one non-limiting example of the injection ports29that have slot shapes.FIG. 11shows another non-limiting example of the injection ports29that have round shapes. It should be understood by the person skilled in the art that the injection port may have any suitable shape.

Of course, the thickness adjustable adhesion technique also may be used to integrate the membrane switch into the user-interface assembly, for example by forming at least one injection port extending to the bottom of the first recess. In this case, the bottom adhesive layer of the membrane switch may be omitted.

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the present disclosure. The attached claims and their equivalents are intended to cover all the modifications, substitutions and changes as would fall within the scope and spirit of the present disclosure.