Patent Publication Number: US-11030972-B2

Title: Electronic device and method for controlling same

Description:
TECHNICAL FIELD 
     The disclosure relates to an electronic device and a method for controlling thereof and more particularly, to an electronic device capable of measuring chromaticity and luminance of a display and a method for controlling thereof. 
     BACKGROUND ART 
     The display device includes a display panel for displaying an image, and is a device capable of displaying an image based on broadcast signals or image signals/image data of various formats, and is implemented as a TV or a monitor. The display panel is implemented in various types, such as liquid crystal panels, plasma panels, or the like, according to characteristics thereof, and is applied to various display devices. 
     However, differences between luminance and chromaticity, which is a light output of each pixel, are occurred in a displayed image due to problems of its electrical, physical and optical characteristics and a problem in processing. Accordingly, even if the same broadcast program is provided to the display device through public air or satellite, the color of the broadcast program shown on the display device slightly may vary depending on the display device. 
     In addition, if the light output of each pixel of high resolution display device is not uniform with each other, problems such as screen blur, or the like may occur. 
     In order to solve this problem, chromaticity and luminance regarding each pixel of the display panel have heretofore been measured using a color measuring instrument capable of measuring the chromaticity and luminance, and have been corrected the chromaticity and luminance of the display panel in the method chromaticity and luminance method. 
     However, the conventional color measuring instrument should have a color filter for various types of light sources such as LED, tungsten, or the like, and there has been a difficulty in measuring chromaticity and luminance of other types of light sources other than the light source of the type corresponding to the color filter. If the measured chromaticity and luminance are inaccurate, it may not implement satisfactory luminance and chromatic uniformity even if correction is properly performed. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Problem 
     The disclosure provides an electronic device capable of accurately measuring chromaticity and luminance of various types of light sources to solve the problems described above and a method for controlling thereof. 
     Technical Solution 
     An electronic device according to an embodiment of the disclosure comprises a sensor, a storage unit storing a color matching function (CMF), which has been pre-defined according to characteristics of a light source, and a processor configured to: acquire spectral information regarding at least one pixel of a display panel by using the sensor, acquire color stimulus values regarding the at least one pixel on the basis of the stored CMF and the acquired spectral information, and acquire a correction coefficient regarding at least one pixel of the display panel on the basis of the acquired color stimulus values. 
     The storage unit may be configured to store a CMF pre-defined by type of light source having different characteristics, and wherein the processor may be configured to select a CMF corresponding to a light source of the display panel among the stored CMFs, and acquire color stimulus values regarding the at least one pixel on the basis of the selected CMF and the acquired spectral information. 
     Also, the storage unit may be configured to further store light source spectral information pre-defined by type of light source having different characteristics, and wherein the processor may be configured to select one light source spectral information among the stored light source spectral information on the basis of a correlation between spectral information regarding the acquired at least one pixel and the stored light source spectral information, and select a CMF of a light source corresponding to the selected light source spectral information as a CMF corresponding to a light source of the display panel. 
     The electronic device of claim  2  may further include an input unit, wherein the processor may be configured to select a CMF selected according to a user input input through the input unit among the stored plurality of CMFs as a CMF corresponding to the light source of the display panel. 
     The processor may be configured to, on the basis of the color stimulus values regarding the acquired at least one pixel and a preset target color stimulus value, calculate correction coefficients for correcting color stimulus values regarding the acquired at least one pixel and store the calculated correction coefficients in the storage unit. 
     The processor may be configured to acquire the color stimulus values regarding the at least one pixel by adding up a multiplication of the color stimulus values of the stored CMF and the color stimulus values of the acquired spectral information. 
     The at least one pixel may be configured to include point light sources corresponding to red (R), green (G), blue (B), respectively, and wherein the processor may be configured to acquire spectral information and color stimulus values regarding the R, G, and B, respectively. 
     A method for controlling electronic device according to an embodiment of the disclosure may include acquiring spectral information regarding at least one pixel of a display panel, acquiring color stimulus values regarding the at least one pixel on the basis of a CMF which has been pre-defined according to characteristics of a light source of the display panel and the acquired spectral information, and acquiring a correction coefficient regarding at least one pixel of the display panel on the basis of the acquired color stimulus values. 
     The acquiring the color stimulus values may include selecting a CMF corresponding to a light source of the display panel among CMFs pre-defined by type of light source having different characteristics, and acquiring color stimulus values regarding the at least one pixel on the basis of the selected CMF and the acquired spectral information. 
     The selecting may include, on the basis of a correlation between spectral information regarding the acquired at least one pixel and light source spectral information pre-defined by type of light source having different characteristics, selecting one light source spectral information among the pre-defined light source spectral information and selecting a CMF corresponding to the selected light source spectral information as a CMF corresponding to a light source of the display panel. 
     The selecting may include selecting a CMF selected according to a user input among the stored plurality of CMFs as the CMF corresponding to the light source of the display panel. 
     The acquiring the correction coefficient may include calculating a correction coefficient for correcting color stimulus values regarding the acquired at least one pixel by the pixel unit on the basis of color stimulus values regarding the acquired at least one pixel and a preset target color stimulus value. 
     The acquiring color stimulus values may include acquiring the color stimulus values rewarding the at least one pixel by adding up a multiplication of the color stimulus value of the stored CMF and the color stimulus value of the acquired spectral information by a preset wavelength unit. 
     The at least one pixel may include point light sources corresponding to red (R), green (G), and blue (B), respectively, wherein the acquiring the color stimulus values may include acquiring spectral information and color stimulus values regarding the R, G, and B, respectively. 
     Effect of the Invention 
     According to various embodiments of the disclosure, a physical color filter is not required, thereby reducing costs, and chromatic/luminance deviation of a display can be corrected by easily changing a CMF for each light source type of the display, thereby increasing convenience. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram schematically illustrating a configuration of an electronic device according to an embodiment; 
         FIG. 2  is a view illustrating a graph of a CMF; 
         FIG. 3  is a view illustrating luminance/chromatic deviations according to a characteristic difference of a point light source and a part of the display in which the luminance/chromatic deviations corrected; 
         FIG. 4 , with respect to conventional art, is a view illustrating a method how color stimulus values are measured through a colorimeter implemented by a color filter that a CMF is reelected; 
         FIGS. 5A to 5C  are views illustrating a method for measuring color stimulus value of a point light source according to an embodiment; 
         FIG. 6  is a view illustrating a method for correcting chromaticity and luminance of a point light source by using measured color stimulus values of the point light source according to an embodiment; 
         FIG. 7  is a view illustrating a method for selecting one CMF among stored CMFs according to spectral information; 
         FIG. 8  is a block diagram schematically illustrating a configuration of an electronic device according to another embodiment; and 
         FIG. 9  is a flowchart illustrating a method for controlling an electronic device according to an embodiment of the disclosure 
     
    
    
     BEST MODE FOR IMPLEMENTING THE DISCLOSURE 
     Mode for Implementing the Disclosure 
     Before specifically describing the present disclosure, a method for demonstrating the present specification and drawings will be described. 
     First, as terms used in the present specification and claims, general terms have been selected by considering functions in diverse exemplary embodiments. However, such terms may be varied depending on an intention of those skilled in the art, a legal or technical interpretation, an emergence of a new technology, and the like. Further, some terms may be terms which are arbitrarily selected by an applicant. Such terms may be construed according to meanings defined in the present specification, and may also be construed based on general contents of the present specification and a typical technical concept in the art unless the terms are not specifically defined. 
     Further, the same reference numerals or symbols described in the accompanying drawings of the present specification denote parts or components that perform substantially the same function. For convenience of explanation and understanding, the description will be provided using the same reference numerals or symbols in different exemplary embodiments. That is, although a plurality of drawings may illustrate the components having the same reference numeral, the plurality of drawings do not mean one exemplary embodiment. 
     In addition, in order to distinguish between the components, terms including an ordinal number such as “first”, “second”, etc. may be used in the present specification and claims. The ordinal number is used to distinguish the same or similar components from each other, and the meaning of the terms should not be construed as being limited due to the usage of the above-mentioned ordinal number. As an example, the components coupled to the ordinal number should not be construed as a use order, a layout order, or the like being limited by the number. The respective ordinal numbers are interchangeably used, if necessary. 
     In the present specification, the singular expression includes the plural expression unless the context clearly indicates otherwise. In the present application, the terms “include” and “consist of” designate the presence of features, numbers, steps, operations, components, elements, or a combination thereof that are written in the specification, should be understood that they do not exclude the presence or possibility of addition of one or more other features, numbers, steps, operations, components, elements, or a combination thereof. 
     A term “module”, “unit”, “part”, or the like, in the exemplary embodiment of the present disclosure is a term for referring to the component performing at least one function or operation, and such component may also be implemented in hardware or software or a combination of hardware and software. In addition, a plurality of “modules”, “units”, “parts”, or the like may be integrated into at least one module or chip and may be implemented in at least one processor (not illustrated), except for a case in which they need to be each implemented in individual specific hardware. 
     In addition, in the exemplary embodiment of the present disclosure, it will be understood that when an element is referred to as being “connected to” another element, it can be directly “connected to” the other element or other elements intervening therebetween may be present. In addition, unless explicitly described otherwise, “comprising” any components will be understood to imply the inclusion of other components rather than the exclusion of any other components. 
     Hereinafter, embodiments of the present disclosure will be explained with reference to the drawings. 
       FIG. 1  is a block diagram schematically illustrating a configuration of an electronic device according to an embodiment. 
     The electronic device  100  of the disclosure is a device measuring chromaticity and luminance of the display panel  200 . The electronic device  100  may include a sensor  110  for detecting a spectrum of the display panel  200 , a storage unit  120  for storing a color matching filter (CMF) pre-defined according to characteristics of a light source, color stimulus values calculated according to detected chromaticity and luminance, and a correction coefficient for calibrating the color stimulus values, and a processor  130  for overall control of the electronic device  100 . 
     Firstly, the sensor  110  may be configured to acquire the spectral information of the light emitted from each pixel by sensing intensity and wavelength of the light emitted from each pixel constituting the display panel  200 . Each pixel constituting the display panel  200  may be a point light source with a self-luminous type, and the point light source may output R (Red), G (Green), and B (Blue), respectively. The sensor  110  may detect the RGB color of each point light source. The sensor  110  may be implemented as an image sensor such as a CMOS or a CCD, or may be implemented as a optical sensor. 
     The storage unit  120  may be a component for storing the color matching function (CMF) corresponding to the light source to be measured. The CMF is a function used in the process of measuring to equalize the luminance and chromaticity in the display of a specific light source, and is numerical definition of a standard observer&#39;s color response. A CIE XYZ color space may be expressed as a combination of three color stimulus values X, Y, and Z: blue, green, and red, and the CMF is defined as the response function x (λ), y (λ), z (λ) of cone cells to X, Y and Z, respectively. 
     Referring to  FIG. 2 , a spectral graph according to CMF is defined at a wavelength of about 340 nm to 800 nm, and x-axis represents a wavelength of light and y-axis represents the color stimulus values.  FIG. 2  illustrates the spectral graph according to CMF (CIE-1931 CMF) defined according to the XYZ color space established in 1931 at CIE. 
     The storage unit  120  may store data in which a wavelength of the CMF is matched with the color stimulus values for each predetermined unit of a wavelength such as 1 nm unit or 5 nm unit of the CMF. Data in which the wavelength and color stimulus values of the CMF are matched may be stored in the form of a look-up table. 
     Meanwhile, the CMF may be differently defined according to the type of light source. As various light sources for displays have been developed, the luminance and chromaticity of the display may be able to be more accurately uniformed by using the color stimulus values X, Y, and Z measured using CMF corresponding to the characteristics of each light source. In particular, when it comes to a light source having a narrow half-width, a difference between the spectral graph and visual recognition characteristics have been occurred according to CIE-1931 CMF, so that a CMF suitable for each type of light source was defined. 
     Accordingly, the storage unit  120  may store a plurality of different CMFs pre-defined by type of light source to be measured. 
     The storage  120  may be realized as one of a hard disk drive (HDD), a solid state drive (SSD), a dynamic RAM (DRAM) memory, a static RAM (SRAM) memory, a ferroelectric RAM (FRAM) memory, a flash memory, or the like. 
     Meanwhile, the processor  130  controls the overall operations of the electronic device  100 . Specifically, the processor  130  may acquire spectral information regarding at least one pixel of the display panel  200  by using the sensor  110 , and the color stimulus values X, Y, and Z may be acquired for R, G, and B regarding at least one pixel, respectively, according to the acquired spectral information. Specific explanation thereof will be made hereinafter with reference to  FIGS. 5A to 5C . 
       FIG. 3  is a view illustrating luminance/chromatic deviations according to a characteristic difference of a point light source and a part of the display in which the luminance/chromatic deviations corrected. 
     Respective self-luminous light sources constituting the display panel  200  may be different in their characteristics of chromaticity and luminance in a process of processing. Accordingly, even if the same RGB values are output as shown in  FIG. 3(A) , chromaticity and luminance perceived by human eyes for each pixel may all be different. 
     Accordingly, a process is required to uniformly correct chromaticity and luminance of each pixel of the display panel  200 , as shown in  FIG. 3B , and the conventional luminance/chromatic correction was performed through a colorimeter. The conventional colorimeter includes a sensor  40  capable of sensing chromaticity and luminance for each pixel of the display panel  200 , as shown in  FIG. 4 . 
     The sensor  40  may include an imaging lens, a color filter wheel, a neutral density filter wheel, a shutter, and a CCD detector, and the colorimeter may use such sensors to measure XYZ values for R, G, and B regarding each pixel of the display panel  200 , respectively. 
     Based on the measured XYZ value and a preset target XYZ value (reference XYZ value), a correction coefficient (3×3 matrix data) may be calculated to correct the measured XYZ value to the target XYZ value, and the calculated correction coefficient is input to the display panel  200  and used to correct chromaticity and luminance characteristics of each light source. Accordingly, as illustrated in  FIG. 3B , each pixel of the display panel  200  may be able to express uniform chromaticity and luminance. 
     However, the method of measuring the XYZ value for each pixel of the display panel  200  using the colorimeter  40  had a disadvantage in that it cannot be used in all display panels having different types of light sources. Since the color filter of the colorimeter  40  reflects the CMF according to the characteristics of a specific type of light source, a colorimeter with another color filter was needed to measure chromaticity and luminance of a light source with a different type other than a light source of the corresponding specific type. That is, a colorimeter having a plurality of different color filters was required to measure chromaticity and luminance of a display panel having a plurality of different types of light sources. 
     The electronic device  100  of the disclosure, without physically implementing the color filter, may store the spectral information of the CMF, and acquire the XYZ value regarding each pixel of the display panel by using the stored spectral information and the spectral information of each pixel of the display panel, and furthermore, may store the pre-defined CMF by type of different light sources and acquire the XYZ value by using a CMF corresponding to types of respective light sources of the display panel. The correction coefficient for each pixel of the display panel may be calculated based on the acquired XYZ value. 
     Hereinafter, a method of acquiring XYZ values of respective light sources of the display panel using CMFs corresponding to the light source types of the display panel will be described in detail with reference to  FIGS. 5A to 5C . 
       FIGS. 5A to 5C  are views illustrating a method for measuring color stimulus value of a point light source according to an embodiment. 
     As illustrated in  FIG. 5A , with respect to the display panel  200 , which is a type of a point light source is A, the sensor  110  of the electronic device  100  measures spectra for R, G, B, respectively, of each pixel of the display panel  200 . Based on the measured spectra, the processor  120  may acquire spectral information on R, G, and B, respectively, for each pixel of the display panel  200 .  FIG. 5A  is a graph showing spectral information (S 1  to Sn) for R of respective pixels. 
     Since chromaticity and luminance of each pixel of the display panel  200  are different from each other, the spectral graph of each pixel may also be shown differently as illustrated in  FIG. 5A . 
     Meanwhile, the storage unit  120  of the electronic device  100  may store a plurality of different CMFs pre-defined according to characteristics of respective light sources. For example, as illustrated in  FIG. 5B , the storage unit  120  may store CMFs corresponding to characteristics of an A type light source to an n type light source ( 51 - 1  to  51 - n ), respectively. 
     In this case, the processor  130  may select a CMF corresponding to the light source of the display panel  200  among the plurality of CMFs ( 51 - 1  to  51 - n ). A method for selecting the CMF may be implemented in various ways. 
     According to an embodiment, the processor  130  may select a CMF of a light source having a spectral characteristic most similar to spectral information of at least one among spectral information for each acquired pixel as a CMF corresponding to a light source of the display panel  200 . The spectral information (S 1  to Sn) for each pixel is slightly different, but is generally similar as it includes a common type of light sources. Thus, the processor  130  may select a CMF of a light source having spectral information most similar to spectral information (S 1  to Sn) of each pixel among the plurality of CMFs stored in the storage unit  120 . 
     In order to compare the spectral information, the storage unit  120  may further store a plurality of light source spectral information pre-defined by type of light source having different characteristics. In other words, the CMF and the light source spectral information may be matched by type, respectively, and be stored in the storage unit  120 . 
     As illustrated in  FIG. 7 , the processor  130  may calculate at least one spectral information among the spectral information (S 1  to Sn) regarding each pixel acquired and a correlation between light source information by type stored in the storage unit  120 , respectively. The processor  130  may select the A light source having the light source spectral information indicating the highest correlation (97%) with the acquired at least one spectral information among the plurality of stored light source spectral information, and select the CMF of the selected A light source as a CMF corresponding to the A light source of the display panel  200 . Since a method for calculating the correlation between the two data is widely known, a detailed description will be omitted. 
     Meanwhile, the processor  130  may select the CMF selected by the user among a plurality of stored CMFs  51 - 1  to  51 - n . To this end, the electronic device  100 ′ according to another embodiment of the disclosure may further include an input unit  140  that may receive a user input for selecting a CMF, as shown in  FIG. 8 . The input unit  140  may be implemented as a well-known configuration such as a physical button, a keypad, a touch panel, or the like, and may be obviously understood in the art, and thus a detailed description thereof will be omitted. 
     The selected CMF may be represented by a graph indicating spectral information of the tristimulus value functions x (λ), y (λ), z (λ). 
     Meanwhile, as shown in  FIG. 5C , the processor  130  may integrate the spectral information (S 1 ˜Sn) for an R of each pixel and a product of the color stimulus value functions x (λ), y (λ), z (λ) of the selected CMF, respectively, to calculate the color stimulus values X, Y and Z for the R of each pixel. Specifically, the processor  130  may multiply the spectral information S 1  of R of a first pixel and the color stimulus value functions x (λ), y (λ), and z (λ) of the stored CMF by preset wavelength unit (1 nm or 5 nm, etc.), respectively, to calculate the color stimulus values X, Y, and Z for R of the first pixel by adding the multiplied values. 
     Likewise, the processor  130  may integrate the multiplication of the spectral information S 1  to Sn for G of each pixel and the color stimulus value functions x (λ), y (λ), and z (λ) of the selected CMF, respectively, to calculate the color stimulus values X, Y, and Z for G of each pixel. In addition, the processor  130  may integrate the multiplication of the spectral information S 1  to Sn for B of each pixel and the color stimulus value functions x (λ), y (λ), and z (λ) of the selected CMF, respectively, to calculate the color stimulus values X, Y, and Z for B of each pixel. 
     The processor  130  may use the color stimulus values X, Y, and Z for the acquired R, G, and B of each pixel and target color stimulus values X′, Y′, and Z′ pre-stored in the storage unit  120  to calculate the correction coefficients for correcting the color stimulus values X, Y, and Z of each pixel. As shown in  FIG. 6 , the processor  130  may calculate correction coefficient with a 3×3 matrix data form that converts input video signals R, G, and B into output video signals R′, G′, and B′ for correcting to convert the color stimulus values X, Y, and Z of each pixel outputting an image signal input to the display panel  200  to be measured into the target color stimulus values X′, Y′, and Z′. 
     The calculated correction coefficient may be input to the display panel  200  to uniformly correct luminance and color of each pixel of the display panel  200 . 
       FIG. 9  is a flowchart illustrating a method for controlling an electronic device according to an embodiment of the disclosure. 
     Firstly, spectral information on at least one pixel of the display panel is acquired (S 910 ). 
     Thereafter, color stimulus values for at least one pixel are acquired based on the CMF and the acquired spectral information pre-defined according to characteristics of the light source of the display panel (S 920 ). In this case, the CMF corresponding to the light source of the display panel may be selected among the CMFs pre-defined by type for each light source having different characteristics from each other, and the color stimulus values regarding at least one pixel may be acquired based on the selected CMF and the acquired spectral information. Specifically, the spectral information acquired by each predetermined wavelength unit and the color stimulus values regarding at least one pixel may be acquired by weighted summing up with the stored CMF data. 
     Particularly, the CMF corresponding to the light source having the highest correlation may be selected as a CMF corresponding to the light source of the display panel by calculating a correlation between the acquired spectral information regarding at least one pixel and the spectral information by the stored light source. 
     In another embodiment, a user may directly select a CMF suitable for a light source of a display panel among a plurality of stored CMFs. 
     Thereafter, a correction coefficient regarding at least one pixel of the display panel is acquired based on the acquired color stimulus values (S 930 ). In this case, based on the acquired color stimulus values regarding at least one pixel and the predetermined target color stimulus values, a correction coefficient for correcting the color stimulus values regarding the acquired at least one pixel may be calculated by pixel unit. 
     According to various embodiments of the disclosure, when measuring the chromaticity and the luminance of the light source, the CMF corresponding to the light source to be measured does not need to be implemented as a color filter, respectively, and cost reduction and an increase of convenience may be occurred by calculating in software. 
     The method for controlling an electronic device according to various embodiments described above may be implemented as a program and stored in various recording media. In other words, a computer program which is processed by various processors to execute the above-described various control methods may be stored and used in a recording medium. 
     For example, a non-transitory computer readable medium may be provided that stores a program the performs acquiring spectral information regarding at least one pixel of the display panel, acquiring color stimulus values regarding at least one pixel based on the CMF pre-defined according to characteristics of the light source of the display panel and the acquired spectral information, acquiring a correction coefficient regarding at least one pixel of the display panel based on the acquired color stimulus values. 
     The non-transitory computer readable recording medium refers to a medium that stores data and that can be read by devices. In detail, the above-described various applications or programs may be stored in the non-transitory computer readable medium, for example, a compact disc (CD), a digital versatile disc (DVD), a hard disc, a Blu-ray disc, a universal serial bus (USB), a memory card, a read only memory (ROM), and the like, and may be provided. 
     While the present disclosure has been shown and described with reference to various embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents.