The present invention generally relates to portable electronic devices and more particularly to a method and apparatus for providing a desirable appearance for the housing thereof.
The market for electronic devices, especially personal portable electronic devices, for example, cell phones, personal digital assistants (PDA's), digital cameras, and music playback devices (MP3), is very competitive. Manufactures are constantly improving their product with each model in an attempt to cut costs and to meet production requirements.
The look and feel of personal portable electronics devices is now a key product differentiator and one of the most significant reasons that consumers choose specific models. Consumers are enamored with appearance features that reflect personal style. Consumers select them for some of the same reasons that they select clothing styles, clothing colors, and fashion accessories. From a business standpoint, outstanding designs (form and appearance) may increase market share and margin.
Many portable electronic devices have been made with metallic looking surfaces, which have great appeal to consumers. The Motorola RAZR cell phone, for example, has a magnesium housing. However, it is very difficult to provide a uniform metallic look over the entire phone surface. In a commercially available example, a thin semi-transparent gold coating is deposited on the protective transparent material overlying the LCD display. The surface looks gold until the LCD backlight is activated. Then a fraction of the LCD light penetrates the semitransparent coating to reveal the display. This scheme is inefficient with power, but more importantly, since the reflective surface is still present, the contrast of the emissive display is poor under bright lighting conditions encountered outdoors.
The other trend is the use of very high gloss materials for the housing with a focus on the aesthetic appeal of the device, which suffers a similar aesthetic and functional degradation due to scratches, scuffing, abrasions and the like. This is particularly true for products which receive significant handling, such as persona data assistants (PDAs) and cell phones. This has led to the result that any type of scratches, scuffing, or abrasions is especially undesirable as it tends to be very noticeable and can degrade both the functional and aesthetic performance of the device. This degradation may also lead to breakage of the display cover.
Many materials have been mentioned for use as hard coatings. A single layer ceramic coating including Al2O3, ZrO2, and DLC (amorphous diamond like carbon) is most common. Al2O3, commercially available as coatings of, for example, cutting tools, is hard and chemically inert, and is excellent as an anti-oxidation coating for high temperatures. It has a smooth surface with minimum friction and very low optical absorption in the visible range extending to ultraviolet. Corundum, the most stable phase of Al2O3, has a high hardness but requires a deposition temperature as high as 1000 degrees C., which is too high for coatings of electronic devices and leads to significant thermal stress. ZrO2 requires stabilization. DLC has issues with the ability to control bonding, adhesion to substrates, and absorption in the visible range. Composite layers include TiN+SiN which is not transparent, SiO2/resin which is a DVD coating, and Al2O3/SiO2/poly which is used on wood floors. Multilayer/Superlattice materials include SiON/polymer/SiON (an OLED encapsulation) as a permeation barrier and Ti/Zr/N (on cutting tools) which is non-transparent.
However, the above mentioned approaches do not provide a housing that provides a metallic appearance, that is resistance to scratches and abrasions, and that is transmissive to radio frequency signals.
Accordingly, it is desirable to provide an electronic device housing having a metallic appearance that is resistant to scratches and abrasions and is transparent to radio frequency signals. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.
Embodiments of the present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and
The exemplary embodiments described herein include several technologies wherein incorporated metal surfaces, metal particles, or shiny particles into device structures may be actuated. The grain sizes of the particles can be adjusted to achieve the desired reflections.
Many consumers like their electronic devices to have a metallic appearance. A metallic appearance is more than just a color. Yellow-orange does not provide the look of gold, nor does gray represent stainless steel. Metals look the way they do for several reasons. First, the electronic structure of metal reflects a substantial percentage of the incident light, as much as 90%, which is much greater than most other non-metal surfaces. Typical metal surfaces are smooth enough to demonstrate significant specular reflection, rather than diffuse reflection. As a result, a metal's reflective brightness varies with the surface's angle to the light source. This gives metal its characteristic angularly-dependent brightness which varies with the relative orientations of a viewer and a light source. In addition, reflection off metal surfaces is also often polarized. Metals also have grain structures which can act of a collection of small specular reflectors with a distribution of reflecting angles. This can produce a highly reflective, but granular, texture that still maintains a large angularly dependent reflection. Some decorative metals reflect light more efficiently in the yellow and red regions of the spectrum than in the blue and green regions, providing gold and copper colors. A metallic appearance is defined as a surface exhibiting bright, predominantly specular reflections, wherein the reflections vary with the angle of the light source and are a function of the material and the granular characteristics of the surface. Metallic looking paints incorporate reflective additives, such as metal flakes and mica flakes to create the enhanced shiny look, but the paints are subject to damage, such as scratching and fading.
A coating for a housing of an electronic device is provided that includes a non-conductive, doped semiconductor layer on a substrate that is transparent to signals in the radio frequency range. The semiconductor material is doped with a metal having an atomic weight composition below 10% of the combined semiconductor material and the metal, providing a metallic appearance to visible light reflected from the doped semiconductor material. The doped semiconductor material is “hard”, therefore resistant to scratches and abrasions. Optionally, a color imparting layer may be formed over the doped semiconductor material, wherein the desired color is obtained by selecting the type of material and/or thickness of the color imparting layer. The color imparting layer provides additional scratch and abrasion resistance. The doped semiconductor layer may be patterned, and a thickness selected, to provide transparency to visible light, for example, to provide viewing of a display.
Referring to
The exemplary embodiments described herein may be fabricated using known lithographic processes as follows. The fabrication of integrated circuits, microelectronic devices, micro electro mechanical devices, microfluidic devices, and photonic devices, involves the creation of several layers of materials that interact in some fashion. One or more of these layers may be patterned so various regions of the layer have different electrical or other characteristics, which may be interconnected within the layer or to other layers to create electrical components and circuits. These regions may be created by selectively introducing or removing various materials. The patterns that define such regions are often created by lithographic processes. For example, a layer of photoresist material is applied onto a layer overlying a wafer substrate. A photomask (containing clear and opaque areas) is used to selectively expose this photoresist material by a form of radiation, such as ultraviolet light, electrons, or x-rays. Either the photoresist material exposed to the radiation, or that not exposed to the radiation, is removed by the application of a developer. An etch may then be applied to the layer not protected by the remaining resist, and when the resist is removed, the layer overlying the substrate is patterned. Alternatively, an additive process could also be used, e.g., building a structure using the photoresist as a template.
Though the above described lithography processes are preferred, other fabrication processes may comprise any form of lithography, for example, ink jet printing, photolithography, electron beam lithography, and imprint lithography ink jet printing. In the ink jet printing process, pigments or metal flakes may be combined in liquid form with the oil and printed in desired locations on the substrate.
Referring to
The thickness of the semiconductor material 314 preferably is in the range of 50 to 500 nanometers. At the smaller dimensions, i.e., 50 nanometers, when light in the visible spectrum strikes the surface 316 of the semiconductor material 314, most will pass through the semiconductor material 314, reflecting off of the surface 318 of the substrate 312 (when a substrate non-transparent to visible light is selected). Some of the light entering the semiconductor material 314 will reflect off of the metal doped within the semiconductor material 314 and pass back through the surface 316 resulting in a metallic appearance for the coating 300. Regardless of the materials selected, and their thickness, the coating 300 is transparent to radiation in the radio frequency spectrum.
A second exemplary embodiment, shown in
The color imparted depends on the material selected and the thickness of the color imparting layer 420.
Referring to
Each of the embodiments described herein are examples of an apparatus and method for providing a housing, or a coating for a housing, that provides a metallic appearance, and which is resistant to scratching and the like. A desired color may be selected and the coating may be patterned to provide areas transparent to visible light for viewing within the housing, for example, the viewing of a display.
While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.