Patent Application
20080265387
The present invention generally relates to portable electronic device displays and more particularly to an apparatus and method for preventing smudges including oils and dust from collecting on the displays.
In many portable electronic devices, such as mobile communication devices, displays present information to a user. For example, polymer-dispersed liquid crystal (PDLC) display technology can display video and text information. These optical displays, especially touch panel displays, typically comprise a transparent or a high gloss reflective surface of thermoplastic or glass layer. While these transparent layers have excellent transparency and are physically strong, they suffer both aesthetic and functional degradation due to the build up of oils and other contaminants during use. This is particularly true for the display components of products which receive significant handling, such as personal digital assistants (PDAs) and cell phones. For these displays, any type of fouling is especially undesirable as it tends to be very noticeable to the user and can result in a less than satisfactory viewing experience.
While screen protectors are available for many of these products, they do not offer an optimal solution. Most are based on anti-fouling coatings that reduce smudges, but often become scratched or otherwise degraded, necessitating that the consumer periodically replace them. Some known anti-fouling coatings comprising polymers typically become less transparent due to fabrication methods. Additionally, the fabrication processes for known anti-fouling coatings are unnecessarily complex and expensive. For example, see “Fabrication of Super Water-Repellent Surfaces by Nanosphere Lithography”, Jau-Ye Shiu et al., Mat. Res. Soc. Symp. Proc., Vol. 823, pages W11.4.1-6, 2004.
Accordingly, it is desirable to provide an apparatus and method for preventing smudges including oils and dust from collecting on the portable electronic device displays that does not degrade transparency and is easy to fabricate. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.
An apparatus and method are provided for preventing smudges including oils and dust from collecting on the portable electronic device displays that does not degrade transparency and is easy to fabricate. The apparatus comprises a plurality of islands comprising a transparent material formed on a surface of a transparent substrate. The islands comprise a diameter of between 5 and 200 nanometers and may be formed as deposited on the substrate or by reflow or other further processing. A thin film of functional groups may be formed on the islands.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and
The following detailed description of the invention 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 of the invention or the following detailed description of the invention.
An integrated solution is disclosed that helps maintain the cleanliness of display surfaces by positioning a layer or layers on the display surface that is resistant to the accumulation of smudges and facilitates the removal of smudges, such as droplets of oil, fatty acids, and other contaminants, resulting in a clean viewing area. The layer or layers comprise a roughness created by metal deposition, anneal, or reflow techniques, which may then be coated with a thin film, e.g., a self-assembled monolayer film, resulting in a low cost anti-smudge film.
The layer or layers are formed in a random manner without the use of lithographic methods. Furthermore, the processing employed is compatible with a high volume manufacturing environment with a large manufacturing base of the needed equipment in existence. In addition to the above named properties, the resulting coating also has high optically transmission and high scratch and abrasion resistance.
Although the apparatus and method described herein may be used with an exposed display surface for any type of electronic device, the exemplary embodiment as shown in
The mobile communication device 100 has a first housing 102 and a second housing 104 movably connected by a hinge 106. The first housing 102 and the second housing 104 pivot between an open position and a closed position. An antenna 108 transmits and receives radio frequency (RF) signals for communicating with a complementary communication device such as a cellular base station. A display 110 positioned on the first housing 102 can be used for functions such as displaying names, telephone numbers, transmitted and received information, user interface commands, scrolled menus, and other information. A microphone 112 receives sound for transmission, and an audio speaker 114 transmits audio signals to a user.
A keyless input device 150 is carried by the second housing 104. The keyless input device 150 is implemented as a touchscreen with a display. A main image 151 represents a standard, twelve-key telephone keypad. Along the bottom of the keyless input device 150, images 152, 153, 154, 156 represent an on/off button, a function button, a handwriting recognition mode button, and a telephone mode button. Along the top of the keyless input device 150, images 157, 158, 159 represent a “clear” button, a phonebook mode button, and an “OK” button. Additional or different images, buttons or icons representing modes, and command buttons can be implemented using the keyless input device. Each image 151, 152, 153, 154, 156, 157, 158, 159 is a direct driven pixel, and this keyless input device uses a display with aligned optical shutter and backlight cells to selectively reveal one or more images and provide contrast for the revealed images in both low-light and bright-light conditions.
Referring to
The substrate 206 protects the imaging device 208 and typically comprises plastic, e.g., polycarbonate or polyethylene terephthalate, or glass, but may comprise any type of material generally used in the industry. The thin transparent conductive coating 204 is formed over the substrate 206 and typically comprises a metal or an alloy such as indium tin oxide or a conductive polymer.
Referring to
The TN stack layer 306 utilizes, for example, twisted nematic liquid crystal (TNLC) display technology employing TN optical shutter material in an optical shutter layer 313 and the TN segment electrodes 308 to provide optical shutter operation. While TNLC technology is described herein for the optical shuttering operation, the optical shutter layer 313, sandwiched between the TN backplane electrodes 310 and the TN polymer segment electrodes 308, can alternatively be made using TNLC technology (such as twisted nematic or super twisted nematic liquid crystals), polymer-dispersed liquid crystal (PDLC) technology, ferro-electric liquid crystal technology, electrically-controlled birefringent technology, optically-compensated bend mode technology, guest-host technology, and other types of light modulating techniques which use optical shutter material 313 such as TN polymer material, PDLC material, cholesteric material, or electro-optical material. The electric field created by the electrodes 308, 310 alter the light transmission properties of the TNLC optical shutter material 313, and the pattern of the TN segment electrode layer 308 defines pixels of the display. These pixels lay over the images 151, 152, 153, 154, 156, 157, 158, 159 shown in
Beneath the TN stack layer 306 is an electroluminescent (EL) stack layer 316 separated from the TN stack layer 306 by an ITO ground layer 318. The EL stack layer 316 includes a backplane and electrodes which provide backlight for operation of the display 300 in both ambient light and low light conditions by alternately applying a high voltage level, such as one hundred volts, to the backplane and electrode. The ITO ground layer 318 is coupled to ground and provides an ITO ground plane 318 for reducing the effect on the capacitive sensor layer 304 of any electrical noise generated by the operation of the EL stack layer 316 or other lower layers within the display 300. Beneath the EL stack layer 316 is a base layer 320 which may include one or more layers such as a force sensing switch layer and/or a flex base layer. The various layers 302, 304, 306, 318, 316 and 320 are adhered together by adhesive layers applied therebetween.
Conventional operation of the display 300 is illustrated in
During the same time period 410, the voltages 404, 406, 408 supplied to the TN backplane 310 and the TN segment electrodes 308 are switched between a positive voltage, typically about five volts, and zero volts. The voltage 406 of the portion of the TN segment electrodes 308 that are turned “on” to render corresponding portions of the display 300 over such portion of the TN segment electrodes 308 relatively transparent are switched opposite to the voltage 404 of the TN backplane 310 (i.e., when the voltage 304 of the TN backplane is high, the voltage 406 of the “on” portion of the TN segment electrodes 308 is low). Conversely, the voltage 408 of the portion of the TN segment electrodes 308 that are turned “off” optically shutter corresponding portions of the display 300 over such portion of the TN segment electrodes 308 because their voltage is switched in the same manner as the voltage 404 of the TN backplane 310. It can be seen from
Those skilled in the art will appreciate that other types of imaging devices 200, 300 may be utilized as exemplary embodiments, including, for example, transmissive, reflective or transflective liquid crystal displays, cathode ray tubes, micromirror arrays, and printed panels.
Referring to
The highest water contact angle observed on a flat surface is approximately 120 degrees. It has long been recognized that some surfaces that are not flat exhibit water contact angles much greater than 120 degrees, however. For instance, it is known in nature that the lotus plant that grows in muddy rivers and lakes has leaves that remain clean. The microscopic structure and surface chemistry of the lotus leaves prevent them from getting wet. Water drops roll off of the leafs surface, taking mud and contaminants (smudges) with them (called the lotus effect). The leaf of the lotus plant contains small “bumps” that change the contact angle to a larger magnitude. This larger contact angle is indicative of low surface attraction which allows the water to roll off of the leaf.
“Cassie's law” describes how roughing up a surface increases the effective contact angle θ, for a liquid on a surface. Cassie's law states:
cos θc=γ1 cos θ1+γ2 cos θ2
where θ1=contact angle for component 1 with areal fraction γ1, and
θ2=contact angle for component 2 with areal fraction γ2.
When the second component is air with a contact angle of 180 degrees and since cosine (180)=−1, the equation becomes:
cos θc=γ1(cos θ1+1)−1
Therefore, when γ1 is small and θ1 is large, a large contact angle θc is provided.
“Superhydrophobic” materials with water contact angles in excess of 150 degrees are very well known. Many methods of fabricating them have been described. Such surfaces are very resistant to maintaining water thereon. It is very important to realize, however, that such surfaces are not necessarily oleophobic or is there necessarily a correlation between water and oleic acid contact angles. For example, surfaces have been created which have water contact angles greater than 150 degrees but oleic acid contact angles of less than 10 degrees. Understanding this distinction is very important since flat surfaces typically do not exhibit oleophobic behavior.
In accordance with the exemplary embodiments described herein, an apparatus and method of creating a layer which is both hydrophobic and oleophobic that helps prevent smudges, including oils and dust, from collecting on the display surfaces is shown in
In another embodiment, layers utilizing appropriate thicknesses of tin oxide covered with diamond-like carbon, or tin oxide covered with a layer of tin covered with a layer of diamond-like like carbon will grow “nodules” when annealed in nitrogen, resulting in structures similar to that shown in the picture shown in
These structures of
Referring again to
These various exemplary embodiments provide a transparent cover to the display that is abrasion resistant and prevents smudges, including oils, dust, and other contaminants from collecting on the display's surface.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, 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.
