Current methods for setting white point or white balance for managing color accuracy in televisions with LCD display panels falls into a somewhat acceptable category. Circuitry for attempting to maintain color balance with current LCD televisions requires additional electronic components and power usage to run the circuitry which falls short at providing dynamic white point balance.
White point balance or color balance on televisions relates to color temperature. Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, horticulture, and other fields. The color temperature of a light source is the temperature of an ideal black body radiator that radiates light of comparable hue or color to that of the light source. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e. those on a line from reddish/orange via yellow and more or less white to bluish white. Color temperature is conventionally expressed in degrees of Kelvin.
Color temperatures over 5,000K are called cool colors (blueish white), while lower color temperatures (2,700-3,000 K) are called warm colors (yellowish white through red).
NTSC and PAL TV norms call for a compliant TV screen to display an electrically black and white signal (minimal color saturation) at a color temperature of 6,500 K. Consumer-grade televisions noticeable deviate from this standard. Higher-end consumer-grade televisions generally have their color temperatures adjusted to 6,500 K by using a preprogrammed setting or a custom calibration. This setting is generally set at the factory. Some televisions will also have different preset points customized for retail display, normal, games, sports, etc.
Retail television modes have color temperatures that are higher around 11,000 Kelvin which puts the temperature into blue hues. The side effect of this is to make the picture appear brighter in high light environments which are typical in retail settings.
Current versions of ATSC explicitly call for the color temperature data to be included in the data stream, but old versions of ATSC allowed this data to be omitted. In this case, current versions of ATSC cite default colorimetry standards depending on the format. Both of the cited standards specify a 6,500 K color temperature.
Current digital LCD televisions use complicated circuitry to set color balance. This is generally accomplished by increasing or decreasing the base drive level to the red and blue sub-pixels with a pixel group. Considering that a 1080p television screen has a total of 2,073,600 pixel groups with three times that many sub-pixels (each pixel group has 3 pixels that converts white light to red, blue and green). Eliminating the calculations required to keep the blue and red pixels at some minimum level can result in savings in component counts, PCB traces and power required to run the circuitry.
Applicants recognize the need to use a new simple and inexpensive method or system to dynamically manage white point balance.
An apparatus, method and system for controlling white balance and color temperature by modulating the supply current for a Field Induced ElectroLuminescence (FIPEL) backlight source are described.
The present invention uses a lighting technology called Field Induced Polymer ElectroLuminescence, referred to as FIPEL lighting. The present invention makes us of a FIPEL panel or panels for a backlight system for LCD televisions in one embodiment.
FIPEL panels have the distinguishing feature of being able to emit colored light from any point on the CIE index. Embodiments make use of this feature of FIPEL light panels by setting the color balance of the television by varying the color of the light being transferred to the LCD array panel from a FIPEL backlight. This alleviates the necessity of controlling the color balance of the sub-pixel driver level on more than 4 million sub-pixels.
In another embodiment, the FIPEL panel color balanced backlight is divided into a plurality of individual panels where the color balance of each subpanel is separately controlled. This allows the television to change the color temperature of the different portions of the display to enhance the viewing experience.
To appreciate the simplicity of FIPEL devices reference
Lab quality FIPEL devices are generally fabricated on glass or suitable plastic substrates with various coatings such as aluminum and Indium tin oxide (ITO). ITO is a widely used transparent conducting oxide because of its two chief properties, it is electrical conductive and optical transparent, as well as the ease with which it can be deposited as a thin film onto substrates. Because of this, ITO is used for conducting traces on the substrates of most LCD display screens. As with all transparent conducting films, a compromise must be made between conductivity and transparency, since increasing the thickness increases the concentration of charge carriers which in turn increases the material's conductivity, but decreases its transparency. The ITO coating used for the lab devices discussed here is approximately 100 nm in thickness. In
Substrate 1 in
The differences between the two similar substrates is how ITO coating 6 is positioned. In
Dielectric layer 2 in all cases is composed of a copolymer of P(VDF-TrFE) (51/49%). The dielectric layer is generally spin coated against the non-AL coated 7 side of substrate 1 or non-ITO coated 6 of substrate 4 of the top layer (insulated side). In all cases the dielectric layer is approximately 1,200 nm thick.
Emissive layer 3 is composed of a mix polymer base of poly(N-vinylcarbazole):fac-tris(2-phenylpyri-dine)iridium(III) [PVK:Ir(ppy)3] with Medium Walled Nano Tubes (MWNT). The emissive layer coating is laid onto the dielectric layer to a depth of approximately 200 nm. For the lab devices with the greatest light output the concentration of MWNTs to the polymer mix is approximately 0.04% by weight.
Carriers within the emissive layer then recombine to form excitons, which are a bound state of an electron and hole that are attracted to each other by the electrostatic force or field in the PVK host polymer, and are subsequently transferred to the Ir(ppy)3 guest, leading to the light emission.
When an alternating current is applied across the devices shown in
The frequency of the alternating current applied across the substrates of the FIPEL panel can also determine the color of light emitted by the panel. Any index on the CIE can be duplicated by selecting the frequency of the alternating current. Signal generator 5 may be of a fixed frequency which is set by electronic components or set by a computer process that is software controlled. In this embodiment, the controlling software may include instructions to balance white color or may determine the frequency based on hardware registers or data containing in the digital stream transporting the content to be displayed.
In a display system, a spatial light modulator, e.g., a pixel controllable LCD, is illuminated by the FIPEL lighting panel.
To fully appreciate the simplification of managing color temperature with the invention, the current methodology of managing color temperature is shown as
Pixel Groups 1 through 4 each contain 3 sub-pixels with their associated driver lines from column and row MUX 71. Column and row MUX 71 contains circuitry which turns on gates for individual sub-pixels in rows and columns. Some column and row MUXs provide drive current to groups of rows multiple times a second. Typically, the rows and columns are scanned from the top to the bottom of the LCD array panel. For example, the number of rows in a typical HD LCD display is 1920. Some column and row MUXs will scan groups of 16 rows where half the drive current necessary for a give sub-pixel is provided by the column drivers and half by the row drivers.
White Balance Control 12 sets a base line voltage/current level for all of the Red and Blue sub-pixels contained in the display. Typically Green sub-pixels are not affected by the color balance. The white balance control 12 will, in some televisions, send the white balance voltage and current levels directly to Column & Row MUX 71. In some televisions, the white balance voltage and current levels are sent to RGB Pixel Control. In the latter case, the white balance voltage and current levels are used by RGP pixel control as the base line on top of which the control levels for gating each individual sub-pixel are added to the white balance level then sent to Column & Row MUX 71.
Column & row MUX 71 will have a drive line that runs to each sub-pixel in a given row. Column & row MUX 71 also contains row and column address gates so that individual sub-pixels are addressed. More gates are required to access more rows of sub-pixels that are addressed at a given time the This translates directly into integrated circuits and component counts. A typical 1080×1920 HD LCD display contains 2,073,600 pixel groups with 6,220,800 sub-pixels. To provide circuitry for all of these pixels to be addressed and driven at the same time would require 120 times the gating logic as opposed to the column & row MUX addressing 16 rows at the same time.
The white balance control logic typically contains gates to impress the voltage and current levels onto the red and blue sub-pixels. There are 2,160 red and blue sub-pixels in a 1080 pixel group row and if the column & row MUX addresses 16 rows at a time then there are 34,560 gates required to manage the white balance control within column & row MUX 71.
The depiction contained in
White balance control 12 controls the frequency of frequency generators contained in frequency generator groups 62, 63 and 64.
The number of FIPEL panels shown in
It can be seen in Table 2 that it would be possible to have a FIPEL backlight where the number of FIPEL panels can range from a single panel which covers 1080 columns and 1920 rows. At the extreme of the table, it is possible to have a plurality of FIPEL panels where each panel covers 1 pixel group area in a single column and 1 pixel group area in a single row. In this case, there would be 2,073,600 FIPEL panels each capable of emitting light at a preset color temperature and absolute color from any point on the CIE index. In this extreme scenario, the LCD panel would be eliminated and the FIPEL panels would be the individual light emitters eliminating sub-pixels from the display and result in two thirds fewer control gates to provide the same resolution display panel.
This technique can also be used with the new Samsung screen technology called Electro-wetting Displays which may have backlights or have only have reflective back surfaces that reflect ambient light. A FIPEL panel of the type shown in the embodiments can provide both. When the FIPEL panel is active with this type of display, the display is using a backlight. When the FIPEL panel is turned off, the reflective back surface of the FIPEL panel is reflective. This gives the Electro-wetting Display the best of both worlds.
Although only a few embodiments have been disclosed in detail above, other embodiments are possible and the inventors intend these to be encompassed within this specification. The specification describes specific examples to accomplish a more general goal that may be accomplished in another way. This disclosure is intended to be exemplary, and the claims are intended for cover any modification or alternatives which might be predictable to a person having ordinary skill in the art. For example, other sizes and thicknesses can be used.
Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and 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 artisans may 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 exemplary embodiments.
The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein, may 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 may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. The processor can be part of a computer system that also has a user interface port that communicates with a user interface, and which receives commands entered by a user, has at least one memory (e.g., hard drive or other comparable storage, and random access memory) that stores electronic information including a program that operates under control of the processor and with communication via the user interface port, and a video output that produces its output via any kind of video output format, e.g., VGA, DVI, HDMI, display port, or any other form. This may include laptop or desktop computers, and may also include portable computers, including cell phones, tablets such as the IPAD™, and all other kinds of computers and computing platforms.
A processor may also be implemented as a combination of computing devices, e.g., 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. These devices may also be used to select values for devices as described herein.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, using cloud computing, or in combinations. A software module may reside in Random Access Memory (RAM), flash memory, Read Only Memory (ROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), registers, hard disk, a removable disk, a CD-ROM, or any other form of tangible storage medium that stores tangible, non transitory computer based instructions. An exemplary storage medium is 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 may be integral to the processor. The processor and the storage medium may reside in reconfigurable logic of any type.
In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer.
The memory storage can also be rotating magnetic hard disk drives, optical disk drives, or flash memory based storage drives or other such solid state, magnetic, or optical storage devices. Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL), or wireless technologies such as infrared, radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media. The computer readable media can be an article comprising a machine-readable non-transitory tangible medium embodying information indicative of instructions that when performed by one or more machines result in computer implemented operations comprising the actions described throughout this specification.
Operations as described herein can be carried out on or over a website. The website can be operated on a server computer, or operated locally, e.g., by being downloaded to the client computer, or operated via a server farm. The website can be accessed over a mobile phone or a PDA, or on any other client. The website can use HTML code in any form, e.g., MHTML, or XML, and via any form such as cascading style sheets (“CSS”) or other.
Also, the inventor(s) intend that only those claims which use the words “means for” are intended to be interpreted under 35 USC 112, sixth paragraph. Moreover, no limitations from the specification are intended to be read into any claims, unless those limitations are expressly included in the claims. The computers described herein may be any kind of computer, either general purpose, or some specific purpose computer such as a workstation. The programs may be written in C, or Java, Brew or any other programming language. The programs may be resident on a storage medium, e.g., magnetic or optical, e.g. the computer hard drive, a removable disk or media such as a memory stick or SD media, or other removable medium. The programs may also be run over a network, for example, with a server or other machine sending signals to the local machine, which allows the local machine to carry out the operations described herein.
Where a specific numerical value is mentioned herein, it should be considered that the value may be increased or decreased by 20%, while still staying within the teachings of the present application, unless some different range is specifically mentioned. Where a specified logical sense is used, the opposite logical sense is also intended to be encompassed.
The previous description of the disclosed exemplary embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these exemplary embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
This application is a continuation application of U.S. Ser. No. 13/844,845 filed Mar. 16, 2013, now U.S. Pat. No. 8,988,340 issued Mar. 24, 2015, the disclosure of the parent application is hereby incorporated by reference, in its entirety.
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Number | Date | Country | |
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20150199935 A1 | Jul 2015 | US |
Number | Date | Country | |
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Parent | 13844845 | Mar 2013 | US |
Child | 14666629 | US |