This relates generally to touch surfaces and, more particularly, to an injection molded touch surface having a touch sensor encapsulated therein.
Touch sensitive devices are increasingly used as input devices to a computing system. Generally, a touch sensitive device can include a touch surface to input information via touch and a touch sensor for sensing the touch on the surface. Conventional fabrication of touch sensitive devices can involve laminating the touch sensor to the touch surface using an adhesive. This approach can be problematic, however. Bubbles or voids can form between the touch sensor and the touch surface during lamination and can cause irregular capacitive dielectric between the touch sensor and an object touching the touch surface, thereby making consistent touch sensing difficult. Additionally, treating the touch surface with a primer prior to lamination may be needed to ensure proper adhesion, thereby lengthening fabrication cost and time. When the touch surface is curved or non-planar, these problems can exacerbate.
This relates to injection molding for a touch surface of a touch sensitive device to provide a substantially uniform dielectric between the touch surface and a touch sensor encapsulated therein. A single-shot injection molding method can include positioning a touch sensor inside a mold, injecting a moldable material into the mold around the positioned touch sensor, and molding the injected material to encapsulate the touch sensor at a substantially uniform distance from a surface of the molded material. A double-shot injection molding method can include positioning a touch sensor inside a mold to have a substantially uniform distance from an interior surface of the mold, injecting a first shot of a moldable material into the mold, molding the first shot to contact at least a portion of the touch sensor, injecting a second shot of a moldable material into the mold, and molding the second shot to contact at least the remaining portion of the touch sensor so as to encapsulate the touch sensor. Another molding method can include coating a touch sensor with a moldable material, positioning the coated touch sensor inside a mold, and molding the material to have a substantially uniform thickness on the touch sensor. Injection molding can advantageously provide more consistent touch sensing and reduce fabrication cost and time.
a-1c illustrate a three-dimensional view, a plan view, and a cross-sectional view, respectively, of an exemplary touch sensitive device having an injection molded flat touch surface with an encapsulated touch sensor according to various embodiments.
a-2c illustrate a three-dimensional view, a plan view, and a cross-sectional view, respectively, of an exemplary touch sensitive device having an injection molded curved touch surface with an encapsulated touch sensor according to various embodiments.
In the following description of various embodiments, reference is made to the accompanying drawings which form a part hereof, and in which it is shown by way of illustration specific embodiments which can be practiced. It is to be understood that other embodiments can be used and structural changes can be made without departing from the scope of the various embodiments.
This relates to injection molding for a touch surface of a touch sensitive device to provide a substantially uniform dielectric between the touch surface and a touch sensor encapsulated therein. A single-shot injection molding method can include positioning a touch sensor inside a mold, injecting a moldable material into the mold around the positioned touch sensor, and molding the injected material to encapsulate the touch sensor at a substantially uniform distance from a surface of the molded material. A double-shot injection molding method can include positioning a touch sensor inside a mold to have a substantially uniform distance from an interior surface of the mold, injecting a first shot of a moldable material into the mold, molding the first shot to contact at least a portion of the touch sensor, injecting a second shot of a moldable material into the mold, and molding the second shot to contact at least the remaining portion of the touch sensor so as to encapsulate the touch sensor. Another molding method can include coating a touch sensor with a moldable material, positioning the coated touch sensor inside a mold, and molding the material to have a substantially uniform thickness on the touch sensor.
Using injection molding to provide a substantially uniform dielectric between a touch surface and an encapsulated touch sensor of a touch sensitive can advantageously provide more consistent touch sensing and reduce fabrication cost and time.
a-1c illustrate a three-dimensional view, a plan view, and a cross-sectional view, respectively, of an exemplary touch sensitive device having an injection molded flat touch surface with an encapsulated touch sensor according to various embodiments. In the example of
The injected material can be plastic, acrylic, foam, epoxy, and/or the like. Generally, the injected material can be any moldable material, in various embodiments, being one or more of low cost, nonconductive, low dielectric constant, and low molding temperature and pressure. The touch sensor 110 can include a substrate of polyimide, other polycarbonates, and/or the like, with conductive traces of copper, silver, indium tin oxide (ITO), and/or the like, formed thereon for touch sensing. Generally, the touch sensor 110 can include any material that is flexible, resistant to injection molding temperatures and pressures, and capable of touch sensing.
The injection molding process can be controlled such that the encapsulated sensor 110 can lie at a substantially uniform distance d from the touchable surface 130 of the body 120. This can be done by forming a substantially uniform thickness d of the injected material on the touch sensor 110 substantially free of any voids, bubbles, or other imperfections either in the material or between the material and sensor. As a result, capacitive coupling between an object touching the touchable surface 130 and the touch sensor 110 can be consistent at any location on the surface. Additionally, the injected material can form a substantially uniform capacitive dielectric. Hence, the touch sensitive device 100 can advantageously provide consistent touch sensing.
a-2c illustrate a three-dimensional view, a plan view, and a cross-sectional view, respectively, of an exemplary touch sensitive device having an injection molded curved touch surface with an encapsulated touch sensor according to various embodiments. In the example of
It is to be understood that other shapes are also possible for the touchable surface and the encapsulated touch sensor to conform thereto according to various embodiments.
The touch sensor in the desired configuration can be secured in place inside the mold so that the sensor does not move during subsequent processing (310). The touch sensor can be secured in various ways, such as pins, sliders, lifters, hooks, vacuum, and so on. In some embodiments, the touch sensor can be secured only on its undersurface so that the top surface (i.e., the surface closest to the device's touchable surface) can have a continuous covering of injected material without holes at securing locations caused by the securing tools. In additional or alternatively, the touch sensor can be secured at its sides for similar reasons. Having the continuous covering of injected material can help ensure the consistent capacitive coupling and substantially uniform dielectric described previously.
A shot (i.e., an amount sufficient to fill the mold) of moldable material for forming the body of the touch sensitive device can be injected into the mold around the touch sensor (315). The shot can be controlled so that the injected material can form a touchable surface that is a substantially uniform distance from the touch sensor (320). The control can also ensure that the touch sensor does not move during injection, that the injected material encapsulates the touch sensor while conforming to the mold, and that there are few or no voids, bubbles, or other imperfections in the formed body. Various parameters of the shot can be controlled, such as its temperature, pressure, flow, and so on. In some embodiments, control can be performed by a microprocessor controller.
The injected material can be cured, for example, by air or fluid cooling, to harden the injected material (325). The cured material with the encapsulated touch sensor can be released from the mold for further processing (330). In some embodiments, a protective coating can be applied over the cured material after release from the mold. In some embodiments, an anti-reflective layer can be applied over the cured material after release from the mold.
A first shot of moldable material can be injected into the mold (415). The shot can be controlled so that it is injected at a particular position of the mold (420). For example, the shot can be controlled to contact only a portion of the touch sensor to form a cosmetic or aesthetic layer on the touch sensor. The shot can also be controlled to form some portions of the touch sensitive device, e.g., some portion of the touch surface to be a substantially uniform distance from the touch sensor. The shot can also be controlled to avoid moving the touch sensor during injection and to avoid forming imperfections in the material or between the material and sensor. The injected material can be cured in a similar manner to that described previously (425).
A second shot of moldable material can be injected into the mold around the sensor (430). The second shot can be either the same material or a different material than the first shot, depending on the requirements of the touch sensitive device. The shot can be controlled so that the injected material has a touchable surface that is a substantially uniform distance from the touch sensor (435). The shot can also be controlled either to encapsulate the first cured shot along with the touch sensor or to bond with the first cured shot to complete encapsulation of the touch sensor. The temperature, pressure, flow, and the like can be controlled as described previously.
The injected material can be cured in a similar manner to that described previously (440). The cured device having a touchable surface and an encapsulated touch sensor can be released from the mold for further processing (445).
It is to be understood that additional shots can also be injected into the mold in a multi-shot process. It is further to be understood that the order of the injections can be changed so that the encapsulating shot can be injected first.
The coating material can be molded around the touch sensor to conform to the mold shape (520). In some embodiments, additional coating material can be injected into the mold as needed. The molding can be controlled to ensure that the touch surface formed by the coating material is a substantially uniform distance from the touch sensor (525). Pressure on the coating material, heat applied thereto, and the like can be controlled to distribute the coating material around the touch sensor to encapsulate the sensor. The temperature, pressure, and flow of injected material, if any, can also be controlled.
The coating material can be cured in a similar manner to that described previously (530). The cured material with the encapsulated touch sensor can be released from the mold for further processing (535). In some embodiments, the cured material can be subjected to post-molding finishing to further adjust its thickness, as needed, to provide the desired thickness of the coating material on the touch sensor and hence the desired substantially uniform distance between the touch surface and the encapsulated touch sensor.
Additional methods to those of
The electronic mouse, mobile telephone, media player, and personal computer of
Although embodiments describe touch sensors, it is to be understood that proximity and other types of sensors can also be used.
Although embodiments have been fully described with reference to the accompanying drawings, it is to be noted that various changes and modifications will become apparent to those skilled in the art. Such changes and modifications are to be understood as being included within the scope of the various embodiments as defined by the appended claims.
This application is a divisional of U.S. patent application Ser. No. 12/641,169, filed Dec. 17, 2009, the entire disclosure of which is incorporated herein by reference.
Number | Date | Country | |
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Parent | 12641169 | Dec 2009 | US |
Child | 12985261 | US |