Patent Application
20160131804
The present disclosure relates generally to display systems, and more particularly to the lenses used in display systems for communication devices requiring high impact and electrostatic discharge protection.
Communication devices, particularly portable communication devices such as handheld two-way radios, are increasingly being used to transmit critical data in emergency situations typically through the use of a display lens. Since these communication devices may be used under extreme environmental conditions, the display lens needs to be designed to withstand high impact. For example, ATEX certification requires the display lens to withstand a 4J steel ball impact without jeopardizing the sealing performance of the communication device.
New standards in the public safety environment are now requiring greater than 4J of impact force protection. The ability to increase impact force protection in conjunction with ESD protection is thus highly desirable.
Accordingly, there is a need for a display system that can withstand an impact force higher than 4J that also provides surface ESD protection.
The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed invention, and explain various principles and advantages of those embodiments.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
Briefly, there is provided herein, a display system comprising a display lens coated with a layer of electrostatic discharge material. The display system further comprises an inner housing layer formed of an insulative material providing structural support to the display lens and an outer housing layer formed of an antistatic material providing an electrical discharge path for discharging a charge accumulated on the display lens. A portion of the display lens is mounted between the inner housing layer and the outer housing layer.
The first housing layer 210 forms an inner housing of the display system 200 and provides structural support to the display lens 205. The structural support provided by the inner housing can withstand at least an impact force of 7J. The first housing layer 210 of the display system 200 is formed of an insulative material to provide structural support to the display system. The insulative material may be formed of a plastic, such as a polycarbonate or other thermoplastic, capable of being molded using standard molding techniques, such as injection molding or insert molding. The first housing layer 210 provides a robust joint with the display lens 205 to give primary sealing protection to the display system 200 against dust, water and other fluids.
The display lens 205 is a machined piece part formed of a plastic material capable of being molded, such as a transparent thermoplastic polymer based material. The thermoplastic lens becomes pliable or moldable above a specific temperature and return to a solid state after cooling. In accordance with the various embodiments, the lens 205 comprises flange 225 about its perimeter which provides both a means of retention and a gap area for protecting the edges of the display lens 205. A chemical bond is formed between the first and second housing layers and the flange 225.
The second housing layer 215 forms an outer housing of the display system 200. The second housing layer 215 is made of an antistatic material which, in accordance with the various embodiments, provides an electrical bridging path between the display lens 220 and a user's body. The discharge bridge provides a path for dissipating charge accumulated on the display lens 205 by providing a path to ground. In accordance with some embodiments, the antistatic material is an antistatic plastic, a mixture of polycarbonate and carbon powder, or a mixture of polycarbonate and stainless steel filler having a predetermined surface resistivity in range of 102-1011 ohm/sq. Examples of such plastics, include but are not limited to, polycarbonate (PC), acrylonitrile butadiene styrene (ABS), polycarbonate acrylonitrile butadiene styrene (PC-ABS), and polyoxymethylene (POM) plastic mixed with metal filler of aluminum, carbon, stainless steel, and graphite, to name a few. The metal filler can be in the form of powder or filler. The second housing layer 215 of the display system 200 also provides additional sealing protection to the display system 200 from dust, water and other fluids.
The first housing layer 210 is formed with the display lens 205 attached. A lower cavity portion 305 of the first housing payer 210 provides a shut off surface forming a tight fit for the plastic display lens 205 to hold the part in place before molding. The second housing layer 215 is then molded to the first housing layer 210 and the flange 225 of the display lens 205.
The first housing layer 210 of the display system 200 is designed to provide structural support to the display lens 205 through the incorporation of the lower cavity surface 305. The lower cavity surface 305 retains the lower portion 310 of the flange 225. The lower portion 310 of the flange 225 fits tightly into the lower cavity surface 305 of the first housing layer 210. The lower cavity surface 305 as shown in
In accordance with some embodiments, only a portion of the lower portion 310 of the flange 225, and not the complete lower portion 310 of the flange 225, is inserted into the first housing layer 210 thereby creating a gap 340. The gap 340 prevents damage to the edge(s) of the lens during the molding process which submits the lens to both thermal and mechanical tooling conditions. The molding of the inserted lower portion 310 of the flange 225 with the first housing layer 210 forms a robust bond between the display lens 205 and the first housing layer 210. In accordance with various embodiments, the molding of the lower portion of the display lens 205 and the cavity surface of the first housing layer 210 is done using overmolding, insert-molding, two-shot molding and other molding techniques known in the art. The robust bond between the display lens 205 and the first housing layer 210 gives primary sealing protection to the display system 200 against dust, water, and other fluids.
A bond is formed between the upper portion 315 of the flange 225 and the second housing layer 215 by molding the upper portion 315 of the flange 225 with the second housing layer 215. In accordance with some embodiments, only a portion of the upper portion 315 of the flange 225, and not the complete upper portion 315 of the flange 225, is inserted into the second housing layer 215 for molding in order to prevent any damage to the edge(s) or the display area as described previously. The bond is superior to that of previous approaches because a chemical bond is formed between the ESD material of the display lens 205 and the antistatic material of the second housing layer 215 during molding process. Upon molding, the antistatic material of the second housing layer 215 forms a bridging path with the layer of ESD material on the display lens 205 for discharge of a charge on the display lens 205 in order to provide ESD protection to the display system 200. The second housing layer 215 of the display system 200 also provides additional sealing protection to the display system 200 from dust, water and other fluids.
In accordance with the various embodiments, the robust joint between the portion of the flange 225 and the first housing layer 210 provides primary sealing protection and robustness to the display system 200, thereby allowing the display lens 205 to withstand at least an impact force of 7J. Additionally, the display lens 205 being coated with the layer of ESD material provides an electrically conductive path for electrostatic discharge from the display lens 205. The bonding of the display lens with the second housing layer 210 as previously described forms an electrical bridge or electrical path between the antistatic material of the second housing layer 215 thereby providing a path to discharge electrostatic energy. With such an arrangement, whenever the user touches the communication device 600 with his bare hand, the charge accumulated on the display lens 205 flows through the user's hand to the ground via the electrical bridge path between the display lens 205 and the second housing 215 thus providing surface ESD protection.
The display system formed in accordance with the various embodiments provide surface ESD protection to the communication devices in addition to providing sealing protection from dust, water and other fluids. The molding of the display lens between the two housing layers in accordance with the various embodiments assures robustness at the display lens to withstand at least 7J steel ball impact force without jeopardizing the sealing performance of the display system of the communication device. The improved bond and the elimination of piece parts provide an integral assembly well suited for the portable communication device products.
In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings.
The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
Moreover in this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises . . . a”, “has . . . a”, “includes . . . a”, “contains . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed.
The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2013/051438 | 7/22/2013 | WO | 00 |
