Patent Application
20090141334
The present invention generally relates to portable electronic devices and more particularly to a method and apparatus for changing the appearance of 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. From a business standpoint, outstanding designs (form and appearance) may increase market share and margin.
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. Plastic snap-on covers for devices such as cell phones and MP3 players can be purchased in pre-defined patterns and colors. These snap-on covers are quite popular, and yet they provide a limited customization capability.
Known electronic devices have touch keypads, displays, function buttons and the like that appear through the housing, which alter the appearance of the housing. Furthermore, the consumer may desire to prevent the display, for example, from appearing until desired. Know methods for implementing this look include providing emissive technology such as light emitting diodes under translucent plastic or dark glass. Emissive technology requires a lot of power, and when shining through materials, requires even more power. This is a detriment to battery life. In some cases a shutter technology, like a twisted nematic liquid crystal, is used to hide displays or buttons.
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.
Accordingly, it is desirable to provide an electronic device housing having a tunable metallic appearance. 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
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. For this reason, computer graphics experts have a difficult time creating metal-looking objects. It is difficult to use reflective shutter technology that is known in the art to create a metallic-looking surface. For example, shutters made from liquid crystals, cholesteric liquid crystals, and electrochromic materials, will not look metallic. Note that electrophoretic technology (provided by the company E-ink) does not have a transparent state and will not operate as a shutter. Metallic looking paints incorporate reflective additives, such as metal flakes and mica flakes to create the enhanced shiny look, but the additives are not actively-controllable.
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.
An electronics device is described having a housing, or a region of a housing, that maintains a metallic appearance when not in use, but which transforms into a transparent housing, or region, when desired to reveal device functional elements, such as a display or a touch screen, within the portable electronics device. This transformation is accomplished by providing a surface with metal shutters that can be physically moved on application of a stimulus. A common stimulus would be an electrical signal, but other stimuli are possible. The stimulus may be triggered when the electronic device receives an RF signal or when the user takes a particular action.
The exemplary embodiments teach a surface containing metallic shutters. In many embodiments, a microelectromechanical system (MEMS) including an array of pixels can provide optical switching. In an embodiment utilizing typical solid MEMs, the housing is fabricated as a mirror array using rollable metal strips. When planar, the metal strips present a unified metallic appearance, but when each of the metal strips are rolled to the side, the housing is transparent revealing the element or elements below. Other embodiments employ a liquid form of MEMs using electrowetting or electrocapilliary responses. In one exemplary embodiment, a liquid metal alloy, such as Galinstan®, is modulated through a electrowetting effect, being displaced like a shutter. Galinstan, a registered trademark of Geratherm Medical, provides a highly metallic looking appearance, while the electrowetting technology provides aperture when activated to display the underlying elements. Galinstan is a eutectic alloy of gallium, indium, and tin which is liquid at room temperature (typically freezing at −20° C. (−4° F.)), beads up on hydrophobic surfaces, and has a high reflectivity. Another embodiment includes passivated reflectivel flakes, for example, disposed between a polar liquid and a non-polar liquid, which are modulated in an electrowetting manner. Alternatively, a non-polar fluid (i.e. oil or alkane) is combined with the reflective flakes that are passivated with an insulating oleophilic layer. It should be noted that the surface containing the metallic shutters often includes a bottom substrate and top substrate, with the shutters in between. The substrates provide both a vehicle for electrical contact, and protection from the environment.
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.
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.
A low cost reflective display technology, electrowetting light valves, may be used to produce stacked black and white shutters, colored shutters, or reflective shutters, as described herein, over a surface. Typical electrowetting devices use a low frequency voltage, including DC, to change the wetting properties of a polar fluid (water) on a hydrophobic surface. When devices incorporate a colored oil layer on the hydrophobic surface, electrical actuation moves the polar fluid to the hydrophobic layer, thereby moving the colored oil like a shutter in and out of view. The ‘open’ condition of the shutter is transparent (not black or white) so that the underlying features are visible when the oil is out of view.
Though the transition from metallic appearance to transparency and back, may be accomplished at various trigger points, it is anticipated the metallic appearance would be maintained (by disconnecting the voltage) when the portable electronic device 110 is not in use. When some action occurs, the voltage is applied and the housing becomes transparent, revealing one or more electronic elements within the housing. Examples of the electronic elements include a display 112, a touch screen 114, printed circuit board including numerous transistors, resistors, and the like making up the circuitry 216, 218, 220, 222, 226, and the key inputs 232. Examples of actions prompting the housing 120 to become transparent include an RF signal being received, a button being touched or pushed by the user, or a change detected by a proximity or motion detector.
Referring to
The transparent electrode 814 comprises, for example, indium tin oxide or PEDOT:PSS, and the reflective flakes 834 can be selected from materials such as metals like aluminum and copper, aluminized mylar, metallized plastics, mica, titania-coated mica, and diffraction grating materials. For optimal reflection, the thickness of the flakes must be sufficient to eliminate light transmission. For metallized films, this thickness is typically in the range of 100 to 300 nm as a minimum. For a metallic-looking surface, there is an optimal range for the overall size of the metal flakes (length and width). First, the size of a single pixel must be small enough that the pixelization does not attract the viewer's attention. Typically, this size is less than 500×500 micrometers, and preferably less than 350×350 micrometers. Note that the pixels may take any shape. Individual flakes must be considerably smaller than the pixel size so that the flakes do not alter the basic electrowetting behavior of the cell. Flakes that are 1/10th the area of the pixel and smaller produce good electrowetting response. However, flakes must be large enough that they create a metallic optical response, so typically they are larger than 1 micrometer. Matching the size of the flakes to the grain size of metal surface is a convenient way to select an optimal flake size.
The polar fluid is electrically connected to another electrode on the periphery of the device (not shown). An opaque material 824 overlies a portion of the substrate 822 to “hide” the spacers 816 and reflective flakes 834. When no voltage is applied across the electrodes 814, the reflective flakes 834 assume the position in the optical path as shown, giving a metal appearance to the housing. In another embodiment, the reflective flakes might be incorporated into the non-polar fluid as a mixture. In other embodiments (not shown), the reflective flakes could also be embedded into a polar fluid. Such a system would be an air-polar fluid system. The color of the reflective flakes may be modified by dyes in the polar or non-polar liquids, or filters over the surface. In this way, aluminum flakes can produce a copper or gold appearance. In some cases, the color of the underlying components may need to be adjusted to compensate for the color filter.
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.
