The present invention relates generally to electronic devices, and more specifically to graphical displays for electronic devices.
Display screens, which may be integrated or separate from electronic devices, may provide graphical output (and input in some cases) for electronic devices. These displays may include a glass or transparent plastic covering a light transmitting layer. For example, liquid crystal displays (LCD) operate by backlight a layer of liquid crystal arranged in an optical matrix. The liquid crystals change orientation based on an electrical current. As the crystals are re-oriented, they align with different color filters to vary the colors displayed at each pixel of the display. The display may also include a polarizer to block light having a predetermined polarization transmitted through or into the liquid crystals. However, moisture may seep into and out of the polarizer, which may include one more layers. As moisture seeps into or out of the polarizer, one or more layers of the polarizer may change in shape or dimension, which may affect the shape and/or dimension of the display. For example, as the display bows or bends, spaces or gaps may be created between the display and an enclosure of the display. These spaces or gaps may allow light, for example, from side-firing or other backlights, to escape around the edges of the display. Additionally, the bowing or bending of the display may cause concentrated stresses at attachment points of the display and enclosure, which may lead to cracks or mechanical failure.
Examples of embodiments described herein may take the form of an electronic display configured to provide a visual output. The electronic display includes an optical shutter such as a light transmitting layer configured to transmit at least one color of light and a first polarizer operably connected to the optical shutter. The first polarizer includes an optical filter layer, a protective layer and a moisture barrier positioned on a first surface of either the optical filter or the protective layer.
Other examples of embodiments described herein may take the form of a mobile electronic device. The electronic device may include a processor configured to receive and execute instructions and a display in communication with the processor and configured to provide a visual output. The display includes a transmitting layer and at least one polarizer. The at least one polarizer includes a triacetyl cellulose layer, polyvinyl alcohol layer, and a water impermeable layer positioned on at least one surface of the tri acetyl cellulose layer or the polyvinyl alcohol layer.
Yet other examples of embodiments described herein may take the form of an electronic display configured to provide a visual output. The electronic display may include an optical shutter and a polarizer operably connected to the optical shutter. The polarizer may include an optical filter layer, a protective layer, a reflective polarizer film, and a moisture barrier positioned on a first surface of either the optical filter, the protective layer, or the reflective polarizer film.
This disclosure relates generally to a display including a moisture barrier or layer to prevent moisture seepage between one or more components or layers of the display. The display may provide output and/or input functions for an electronic device, such as a smart phone, tablet, laptop, desktop computer, or the like. For example, the display may present a graphical user interface, show text, images, video, and the like, as well as display other types of visual output. Additionally, the display may include one more sensors for providing input, such a capacitive grid or infrared grid to sense capacitive, resistive, and/or proximal inputs.
In some embodiments, the display may include one or more light polarizers, two or more substrates, and a transmitting layer for producing light. One or both of the polarizers may include a protective layer such as a triacetyl cellulose (TAC) layer, an optical filter such as a polyvinyl Alcohol (PVA) layer, one or more retarders, and one or more adhesives, such as pressure sensitive adhesive (PSA), that secures other layers together. The polarizer also includes a moisture barrier or blocking layer, such as a water impermeable material or component. The moisture barrier may be a separate layer or component, or the moisture barrier may be incorporated into one of the other layers of the display stack. The moisture barrier may substantially prevent moisture from seeping into or out of select layers or portions of the display. For example, the moisture barrier may be positioned over, under, nearby, or adjacent, at least a portion of the PVA layer to prevent moisture from escaping from the PVA layer or entering into the PVA layer. In other embodiments, the moisture barrier may be positioned over one or more of the layers above the PVA layer, such as above the TAC layer, which may be positioned above the PVA layer within the stack of the polarizer.
As the moisture barrier may be substantially impermeable to fluids such as water, it may prevent moisture from penetrating one or more of the layers of the display. This may substantially prevent one or more layers of the display from warping or otherwise changing dimension or shape due to moisture changes such as increases or decreases in humidity. This is because the PVA layer (or other optical filter) may change in shape or dimension as it absorbs or releases moisture. The moisture barrier may thus cause the moisture level within the display stack, for at least the PVA layer, to remain substantially constant, even as the outside environment varies. Thus, in a humid environment the moisture level within the PVA layer of the display stack may be substantially the same as the moisture level in a desert or dry environment. The moisture barrier may help the display in providing relatively consistent performance across different environments, as well as help to ensure that at least one of the dimensions of the various layers of the display may remain substantially constant, regardless of the outer environment of the display.
Turning now to the figures,
In some embodiments, adhesive, glue, or other fastening members may be used to secure the display 102 to the enclosure 104.
In some embodiments, the display 102 may span between two inner edges 110, 112 of the enclosure 104. The display 102 may be configured to be in contact with the inner edges 110, 112 of the enclosure so that there may be little or no space between the inner edges 110, 112 of the enclosure 104 and the display edge 102. In other words, the edges of the display 102 may be substantially flush with the inner edges 110, 112 of the enclosure 104. This type of positioning may prevent light from leaking around edges of the display 102, helping to ensure that the only light emitted from the electronic device 100 may be emitted through the display 102. However, as discussed in more detail below with respect to
The display 102 may include multiple layers arranged in a stack.
In some embodiments, the transmitting layer 118 may have a liquid crystal layer, an optical shutter, or another light characteristic varying sub-layer, one or more color filters 102, and drive members or transistors 122. The transistors 122 may be thin film transistors (TFT) or other switching members and may change the orientation or alignment of the liquid crystals by varying an electrical current applied thereto. As the liquid crystals are re-oriented they may be aligned with a different color filter 120, so that as light is transmitted (e.g., from a backlight) through the light transmitting layer 118 the color of the light may vary as the liquid crystals vary in alignment. For example, a backlight (not shown) may transmit a white light through the display 102, and the orientation of the light crystals (and thus alignment with a particular color filter) may determine the color output for a particular pixel of the display 102.
The filter substrate 116 and the transistor substrate 124 may support the color filters 120 and the transistors 122, respectively. Each the filter substrate 116 and the transistor substrate 124 may be transparent to allow light to be transmitted into and out of the transmitting layer 118. Accordingly, in some embodiments, the filter substrate 116 and the transistor substrate 124 may be glass, plastic, or other similar transparent materials.
The first and second polarizers 114, 126 may selectively block light, based on the polarization of that light. Specifically, the first polarizer 114 may be positioned on a front of the display 102 and may block light transmitted with a predetermined polarization transmitted from the transmitting layer 118 from being transmitted out of the display 102, and the second polarizer 126 may be positioned on a back or rear of the display 106 and block light transmitted with a predetermined polarization from being transmitted into the transmitting layer 118.
Each polarizer 114, 126 may include one or more sub-layers.
The surface treatment layer 130 may be a coating such as an anti-glare and/or an anti-reflection coating to minimize glare and/or reflection from the display 102. In these instances, the surface treatment layer 130 may be applied as a thin coating to the first polarizer 114. The coating layer 132 may be combined with the surface treatment layer 130 or may be separate therefrom. In some instances, the coating layer 132 may be a hard coating that may help to maintain the chemical composition of the polarizer 114, as well as may help to reduce scratches or the like from damaging the polarizer 114, as the polarizer may form the outer surface of the display 102.
The first and second protective layers or TAC layers 134, 138 may be positioned on either side of the PVA layer 136. The TAC layers 134, 138 may form protective layers for the PVA layer 136, as the PVA layer 136 may be fragile and/or dimensionally unstable. The TAC layers 134, 138 may assist in maintaining the dimensions of the PVA layer 136, as well as prevent the PVA layer 136 from cracking or the like. It should be noted that other materials other than TAC may be used as protective layers for the PVA layer 136. For example, other cellulose polymers, ester polymers such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), olefinic polymers such as cyclo-olefin polymer (COP), amorphous polyolefin such as polypropylene (PP) and polypropylene (PE), or the like, may be used in place of TAC.
The PVA layer 136, which is a polarized optical filter, may be a polarizing dichroic film or may otherwise include a dichroic dye. For example, the PVA layer 136 may be a directional optical filter to selectively block light with predetermined polarizations. As briefly described above, the PVA layer 136 may be stretched to form a thin film and as such may be relative fragile and/or dimensionally unstable. Thus, the PVA layer 136 may be sandwiched between the two TAC layers 134, 136, which provide structure and protection.
The first retarder layer 140 may be operably connected to a bottom surface of the second TAC layer 138. The second retarder layer 144 may be operably connected to the first retarder 140 by the first adhesive member 142. The retarders 140, 144 may retard certain wavelengths of light at predetermined angles and/or directions. In this manner, the retarders 140, 144 may compensate and/or improve the oblique angle quality of the display 102.
The first adhesive member 142 may interconnect the first retarder 140 to the second retarder 144. The second adhesive member 146 may interconnect the second retarder 140 to the filter substrate 116, or in the case of the second polarizer 126, may connect to the substrate 108. The adhesive members 142, 146 may be positioned at discrete locations within their respective layers (e.g., at the corners of the preceding layer) or may form their own layer within the stack. In some embodiments, the adhesive members 142, 146 may be layers of pressure sensitive adhesive (PSA) or other similar adhesive.
With respect to the polarizer 114 as shown in
As moisture may travel into and through the TAC layers 134, 138, fluids such as water may enter into the PVA layer 136. As described above, the PVA layer 136 may be somewhat dimensionally unstable and when additional moisture is absorbed or released, the PVA layer 136 may change shape and/or dimension. For example, the PVA layer 136 may bow or bend, see, for example,
As the PVA layer 136 absorbs moisture, it may change in shape and/or in one or more dimensions.
Just as moisture may enter and be absorbed, moisture may escape from the PVA layer 136.
As the display 102 is secured to the substrate 108 by the fastening members 106, with changes in the shape or dimensions of the display 102 (that is, the PVA layer 136), the strain in the display 102 may be concentrated at the point of contact with the fastening members 106. This increased strain may increase the likelihood of mechanical failure of the display 102 and/or cracks within the display 102. Further, as with the display 102 in
In order to prevent the PVA layer 136 from becoming misshapen due to moisture absorption or moisture loss, a moisture barrier layer may substantially prevent moisture from entering or exiting the PVA layer 136.
The moisture barrier 210 may be separate from the TAC layer 134, coated onto the TAC layer 134, or mixed into the TAC layer 134. The moisture barrier 210 may be positioned on an inner or outer surface of the TAC layer 134.
In some embodiments, the polarizer 214 may include a second moisture barrier.
Furthermore, in some embodiments, the moisture barriers 210, 212 may be combined with the surface treatment layer 130 and/or the hard coating layer 132. In these embodiments, the thickness of the polarizer 214 stack may remain substantially the same, while providing the functionality of the moisture barrier 210, 212.
It should be noted that although
As one example, the rear polarizer may include a moisture barrier as a bottom layer.
With reference to
Additionally, as shown in
In some embodiments, the moisture barriers 210, 212, 310 may be transparent inorganic materials that have an optical transmittance equal to or greater than 85%. In some embodiments, the optical transmittance may be equal to or greater than 90%. Additionally, the moisture barriers 210, 212, 310 may have a water permeability or water transmittance characteristic that may range between ten grams per square meter per day per atmospheric pressure to one gram per square meter per day at atmospheric pressure. However, these values are for illustrative purposes only, and other values are envisioned.
In some embodiments, the moisture barriers 210, 212, 310 may be silicon oxide (SiO, SiO2, SiOx) or aluminum oxide (Al2O3, AlOx). The “x” provided for the oxygen component for silicon oxide and aluminum oxide is meant to indicate that the “x” may be an arbitrary number for the oxidation state of the base layer. In other embodiments, the moisture barriers 210, 212 may be magnesium oxide, sodium oxide, or oxides of metals in Periods 3 and 4 of the periodic table. In yet other embodiments, the moisture barrier 210, 212, 310 may be a clay material, or a mixture containing clay components. Also, in embodiments including the second barrier 212, the first moisture barrier 210 may be the same as or different from the second moisture barrier 212, 310. For example, the first moisture barrier 210 may be silicon oxide whereas the second moisture barrier 212 may be aluminum oxide. However, in other embodiments, the two moisture barriers 210, 212 may be substantially the same.
The moisture barrier(s) 210, 212, 310 may be applied as a separate layer, may be a coating for one of the other layers, or may be combined with one of the layers of polarizer 214. For example, the moisture barriers 210, 212, 310 may be vacuum deposited on the TAC layer(s) 134, 138, may be sprayed onto the TAC layer(s) 134, 138, or may be applied by a wet coating by water based solvents or other solvent types.
In some embodiments, the moisture barrier 210, 212, 310 may be applied across the entire length and width of the TAC layer(s) 134, 138. However, in other embodiments, the moisture barrier 210, 212 may only be applied along a portion of the length and/or width. In some instances, moisture may be positioned on only a portion of the TAC layer(s) 134, 138.
The foregoing description has broad application. For example, while examples disclosed herein may focus on displays for electronic devices, it should be appreciated that the concepts disclosed herein may equally apply to polarizers used in other applications. Similarly, although the moisture barrier may be discussed with respect to PVA, the techniques disclosed herein are equally applicable to other resin films or filters. Accordingly, the discussion of any embodiment is meant only to be an example and is not intended to suggest that the scope of the disclosure, including the claims, is limited to these examples.
This application claims the benefit of priority pursuant to 35 U.S.C. §119(e) of U.S. provisional application No. 61/592,578 filed 30 Jan. 2012 entitled “Moisture Barrier for Electronic Displays,” which is hereby incorporated herein by reference in its entirety.
Number | Date | Country | |
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61592578 | Jan 2012 | US |