Patent Application
20170212381
The disclosure relates generally to the liquid crystal displays (LCDs) for mobile devices, and more specifically to devices and methods for LCDs that do not include a bezel.
In the world of smartphones, the bezel functions acts as a shield and protects the back of the phone display. In the early days, cellphones were almost entirely bezel—screens were tiny, and because they lacked touchscreen interaction, that was fine. Once we began to poke and swipe at our screens, though, they got bigger—and the frame that was structurally necessary to keep them stable began to get smaller and smaller.
It follows, by some logic, that the next evolutionary step would be to get rid of the bezel altogether. However, removing a bezel is not without difficulties. As provided above, the bezel offers structural support to smartphones. The bezel is often form fitted to the display screen of a phone, wrapping around the edge and extending beneath the display screen or main lens of the phone. Without bezel protection, the display is more susceptible to any point load or line load to the backside of the display screen, causing visual defects. These permanent and dynamic visual defects are often referred to as dynamic bloom, white/dark/blue spots and edge glow, but may be referred to collectively as “pressure marks.”
Accordingly, there are provided herein devices and methods that allow for bloom or pressure mark protection for a thin liquid crystal display (LCD) product without a formed metal bezel.
In a first aspect, a device is disclosed. The device includes: a liquid crystal display panel; a compression pad having a first surface facing the liquid crystal display panel and a second surface opposite the first surface, the second surface facing away from the liquid crystal display panel, the compression pad substantially filling a volume between the liquid crystal display panel and a bottom chassis; and a bottom chassis that supports the liquid crystal display panel.
In a second aspect, a method of assembling a device is disclosed. The method includes: providing a liquid crystal display panel having a display module reflector; aligning a compression pad assembly with the liquid crystal display panel, the compression pad assembly including a compression pad and a compression pad liner; and removing the compression pad liner from the compression pad.
The details of the present disclosure, both as to its structure and operation, may be understood in part by study of the accompanying drawings, in which like reference numerals refer to like parts. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the disclosure.
The present disclosure describes methods and systems for that allow for bloom or pressure mark protection for a thin LCD product without a formed metal bezel. In some embodiments, the LCD product includes a low compression force pad proximate to the back of a display module reflector, between the display and chassis, to distribute point loads, thereby reducing the occurrence of pressure marks.
In some embodiments, the metal bezel 110 has a thickness of approximately 0.150 mm. Reflector 130 may have a thickness of around 0.082 mm. Adhesive 120 has a thickness of approximately 0.03 mm to approximately 0.08 mm.
As shown, metal bezel 110 does not effectively solve bloom issues or pressure marks associated with LCD module 100. This is because point or edge loads translate through the thin metal bezel 110 and into the LCD module 100 with minimal load distribution. When the load is minimally distributed, the applied pressure is higher through the LCD module 100 (e.g., Pressure=Force/Area). The higher pressure results in more deflection through the layers of the LCD module 100 and reduces the gap between the front and back glass prisms 146, 148 containing the liquid crystal. The effect is bloom.
LCD module 100 also includes a light guide 142, a diffuser film 144, a lower prism 146, and an upper prism 148. In some embodiments, the light guide 142 is constructed from plastic and distributes light from light emitting diodes (LEDs) throughout LCD module 100. In some embodiments, diffuser film 144 is constructed from plastic and spreads light throughout the display. In some embodiments, the lower prism 146 and upper prism 148 are constructed from plastic and are brightness enhancement films that focus light. One prism 146 or 148 focuses light in the horizontal direction and the other prism 146 or 148 focuses light in the vertical direction. Also shown is a rim adhesive 150 that allows the prisms 146, 148 to be secured to LFG 140.
In some embodiments, light guide 142 has a thickness of approximately 0.45 to 0.56 mm. Diffuser film 144 may have a thickness of around 0.05 mm. Lower prism 146 may have a thickness of approximately 0.065 mm and upper prism 148 may have a thickness of approximately 0.095 mm.
LCD module 100 also includes a back polarizer 160, a lower prism 170, an upper prism 180, and a front polarizer 190. In some embodiments, the back polarizer 160 is constructed from plastic and allows light to pass at a specific polarization. In some embodiments, lower prism 170 is constructed from glass and holds a thin film transistor (TFT), which carries electrical current to the liquid crystal and forces it to either block or omit light. In some embodiments, the liquid crystal (not shown) is located between lower prism 170 and upper prism 180. In some embodiments, upper prism 180 is constructed from glass and includes a color filter for red, green, and blue (RGB). Each RGB filter is associated with a transistor that defines the color that will be visible (e.g., a pixel). In some embodiments, front polarizer 190 is constructed from plastic and allows light to pass at a specific polarization.
LCD module 200 also includes a light guide 242, a diffuser film 244, a lower prism 246, and an upper prism 248. In some embodiments, the light guide 242 is constructed from plastic and distributes light from light emitting diodes (LEDs) throughout LCD module 200. In some embodiments, diffuser film 244 is constructed from plastic and spreads light throughout the display. In some embodiments, the lower prism 246 and upper prism 248 are constructed from plastic and are brightness enhancement films that focus light. One prism 246 or 248 focuses light in the horizontal direction and the other prism 246 or 248 focuses light in the vertical direction. Also shown is a rim adhesive 250 that allows the prisms 246, 248 to be secured to LFG 240.
LCD module 200 also includes a back polarizer 260, a lower prism 270, an upper prism 280, and a front polarizer 290. In some embodiments, the back polarizer 260 is constructed from plastic and allows light to pass at a specific polarization. In some embodiments, lower prism 270 is constructed from glass and holds a thin film transistor (TFT), which carries electrical current to the liquid crystal and forces it to either block or omit light. In some embodiments, the liquid crystal (not shown) is located between lower prism 270 and upper prism 280. In some embodiments, upper prism 280 is constructed from glass and includes a color filter for red, green, and blue (RGB). Each RGB filter is associated with a transistor that defines the color that will be visible (e.g., a pixel). In some embodiments, front polarizer 290 is constructed from plastic and allows light to pass at a specific polarization.
A main difference between
Mobile device 300 also includes a main lens 320, which may be constructed of a transparent material such as glass. Main lens 320 may be secured to the LCD module 310 via an optically clear adhesive (OCA) 330. OCA 330 may be approximately 0.15 thick and made from any suitable adhesive.
Also shown are front housing 340, which is secured to main lens 320 via main lens adhesive 350. In some embodiments, front housing is constructed from aluminum die cast and over-molded PC plastic. Main lens adhesive 350 may be any suitable adhesive and is approximately 0.25 mm thick. Proximate to and beneath LCD module 310 is compression pad 360. As shown, compression pad 360 is in contact with a reflector or reflector film (not shown) of LCD module 360. Beneath compression pad 360 is a chassis 370. As shown, chassis 370 is generally a bottom structure of mobile device 300, however in some embodiments, it may be a printed circuit board (not shown) of other internal phone component that is located beneath the LCD module 310.
In some embodiments, compression pad 360 substantially fills a volume between the LCD module 310 and chassis 370. In some embodiments, compression pad 360 effectively minimizes or removes any gaps in mobile device 300 between LCD module 310 and chassis 370. Thus, compression pad 360 is at least partially compressed between LCD module 310 and chassis 370.
The compression force on the compression pad 360 is important, because if compression force is too high, it may overstress the lens bond between main lens 320 and LCD module 330. Too much force from the compression pad 360 may force the main lens 320 to detach from the phone. If compression force is too low, the compression pad 360 may not be effective to distribute point and/or line loads.
Material properties for suitable compression pads 360 are provided in Tables 1 and 2. In some embodiments, compression pad 360 has a thickness of approximately 0.3 mm to 0.4 mm. However, it is appreciated that the thickness of the compression pad 360 may vary, depending on the size of a gap between the LCD module 310 and chassis 370. Additionally, the width and length of compression pad 360 will vary according to the display size.
In some embodiments, compression pad 360 is constructed from a compressible or pliable material such as polypropylene, polyethylene terephthalate, silicone, thermoplastic urethane, or other suitable porous materials. In some embodiments, compression pad 360 has a density of approximately 0.02 to 2.3 g/cm3. The range of densities may be dependent on the material of compression pad 360. For example, a compression pad 360 having a density of 0.02 g/cm3 to 1 g/cm3 is a highly porous compressible pad 360 and a compression pad 360 having a density of 1 g/cm3 to 2.3 g/cm3 is a nonporous compressible pad 360 such as silicone rubber. In some embodiments, compression pad 360 has a 50% compression load of approximately 0.5 to 5 N/cm2.
Also shown in
The reduction in mobile device thickness is provided in Tables 3-5. In Table 3, the mobile device thickness for a device with a display bezel is shown. Gap 2 in Table 3 provides a minimum distance used to prevent bloom or pressure marks in the mobile device using a bezel. Table 4 provides the mobile device thickness for a device without a bezel or compression pad. The Gap in Table 4 provides a minimum distance used to prevent bloom or pressure marks in the mobile device without a bezel or compression pad. Table 5 provides the mobile device thickness for a device with a compression pad.
In some embodiments, adding a pad behind a display distributes point or edge loads over an area, which results in less pressure translating through the liquid crystal layer. As the equation (Pressure=Force/Area) shows, at constant force pressure decreased if the area of applied force is increased. The reduction in pressure reduces the deflection between films and the liquid crystal layer between the two glass prisms. By reducing the deflections, light paths are less interrupted resulting in less cosmetic defects such as bloom.
Benefits associated with using a compression pad in a mobile device assembly may include:
Accordingly, the present disclosure is not limited to only those implementations described above. Those of skill in the art will appreciate that the various illustrative modules and method steps described in connection with the above described figures and the implementations disclosed herein can often be implemented as electronic hardware, software, firmware or combinations of the foregoing. To clearly illustrate this interchangeability of hardware and software, various illustrative modules and method steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled persons can implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosure. In addition, the grouping of functions within a module or step is for ease of description. Specific functions can be moved from one module or step to another without departing from the disclosure.
The various illustrative modules and method steps described in connection with the implementations disclosed herein can be implemented or performed with a general purpose processor, a digital signal processor (“DSP”), an application specific integrated circuit (“ASIC”), a field programmable gate array (“FPGA”) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor can be a microprocessor, but in the alternative, the processor can be any processor, controller, or microcontroller. A processor can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.
Additionally, the steps of a method or algorithm described in connection with the implementations disclosed herein can be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module can reside in computer or machine-readable storage media such as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium including a network storage medium. An example storage medium can be coupled to the processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium can be integral to the processor. The processor and the storage medium can also reside in an ASIC.
