Patent Publication Number: US-9905158-B2

Title: Display device and power control device capable of preventing the degradation of image quality

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority from and the benefit under 35 U.S.C. § 119(a) of Korean Patent Application No. 10-2014-0141032, filed on Oct. 17, 2014, which is hereby incorporated by reference for all purposes as if fully set forth herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a display device and a power control device. 
     2. Description of the Prior Art 
     As the information society develops, display devices for displaying an image are being increasingly required in various forms, and in recent years, various display devices such as Liquid Crystal Displays (LCDs), Plasma Display Panels (PDPs), and Organic Light Emitting Display Devices (OLEDs) have been utilized. 
     The display device includes a display panel, a data drive unit and a gate drive unit. The display panel includes data lines and gate lines, and sub-pixels are defined at each point where the data lines and the gate lines intersect. The display device further includes a data drive unit which provides data signals to the data lines and a gate drive unit which provides scan signals to the gate lines. 
     A transistor is disposed at each sub-pixel defined in the display panel, and a unique characteristic value such as the threshold voltage, mobility, or the like of the transistor in each sub-pixel may change according to the drive time or the unique characteristic value deviation of the transistor between sub-pixels may occur. In another case, when the display device is an organic light emitting display device, the deviation of the degradation of the organic Light Emitting Diode (OLED) in each sub-pixel may occur. This phenomenon may generate a luminance deviation between each of the sub-pixels, thereby decreasing image quality. 
     Thus, in order to compensate for a luminance deviation between each of the sub-pixels, a compensation technique is proposed for compensating for the changes or deviations of the characteristic values of the circuit elements (e.g., transistors, organic light emitting diodes). 
     This sub-pixel luminance deviation compensation senses a voltage at a particular node of a circuit in the sub-pixel, converts the sensed voltage to a digital value and generates sensing data, and then calculates the data compensation amount of data to be supplied to each sub-pixel based on the generated sensing data, and changes the data according to the compensation amount of the calculated data and then supplies the changed data to each sub-pixel, thereby performing sub-pixel luminance deviation compensation. 
     However, sub-pixel luminance deviation compensation causes an unexpected decrease in image quality, such as by creating a block dim phenomenon along the vertical direction. 
     SUMMARY OF THE INVENTION 
     The purpose of embodiments of the present invention is to raise a question of and to provide a solution for a phenomenon of an unexpected decrease in image quality, such as a block dim phenomenon that may occur along the vertical direction, as the sub-pixel luminance deviation compensation is in progress since the sensing reference power, which serves as a reference for converting the sensed analog voltage value into a digital value, fluctuates when generating the sensing data as a basis for the sub-pixel luminance deviation compensation. 
     Another purpose of the embodiments of the present invention is to provide a display device and a power control device capable of preventing the degradation of image quality that may occur unexpectedly by performing the sub-pixel luminance deviation compensation. 
     Another purpose of the embodiments of the present invention is to provide a display device and a power control device capable of acquiring accurate sensing data by exactly generating and providing sensing reference power which serves as a reference when converting analog voltage values sensed at the sub-pixels into digital values as required and thereby enabling an accurate sub-pixel luminance deviation compensation to be performed accordingly. 
     According to an embodiment, a display device is provided, the display device including: an analog-to-digital converter that is connected to a sensing line connected to a sensing node within a sub-pixel on a display panel and converts a voltage at the sensing node sensed via a sensing line into a digital value with reference to the voltage of the sensing reference power to output sensing data; a timing controller that is connected to the analog-to-digital converter via a sensing data transmission line, calculates the data compensation amount based on the sensing data that has been input through the sensing data transmission line, and stores the calculated data compensation amount in a memory; a power generator that generates or regenerates the sensing reference power and then outputs the sensing reference power; and a power controller that, when the sensing reference power is input from the power generator, outputs the sensing reference power input from the power generator to the analog-to-digital converter or controls the power generator to regenerate the sensing reference power. 
     According to another embodiment, a display device is provided, the display device including: an analog-to-digital converter that converts an analog voltage value to a digital value based on a conversion reference voltage; and a power control device that generates the conversion reference voltage and outputs the generated conversion reference voltage to the analog to digital converter, wherein the generated conversion reference voltage is within defined ranges. 
     Further, according to another embodiment, a power control device is provided, the power control device including: a power generator that generates and outputs a sensing reference power which serves as a reference when an analog-to-digital converter converts a voltage at the sensing node on the display panel into a digital value; and a power controller that outputs a sensing reference power to the analog to digital converter when the voltage of the sensing reference power input from the power generator is within a predetermined voltage range, and controls the power generator to regenerate the sensing reference power when the voltage of the sensing reference power input from the power generator is out of the predetermined voltage range. 
     According to embodiments of the present invention as described above, a question can be raised about and a solution can be provided for a phenomenon of an unexpected decrease in image quality such as a block dim phenomenon that may occur along the vertical direction as the sub-pixel luminance deviation compensation is in progress since the sensing reference power which serves as a reference for converting the sensed analog voltage value into a digital value fluctuates when generating the sensing data as a basis for the sub-pixel luminance deviation compensation. 
     Further, according to embodiments of the present invention, a display device and a power control device can be provided which are capable of preventing the degradation of image quality that may occur unexpectedly by performing the sub-pixel luminance deviation compensation. 
     Furthermore, according to embodiments of the present invention, a display device and a power control device can be provided which are capable of acquiring accurate sensing data by exactly generating and providing, as required, sensing reference power serving as a basis when converting analog voltage values sensed at the sub-pixels into digital values and accordingly, performing accurate sub-pixel luminance deviation compensation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a view showing a display device according to embodiments of the present invention; 
         FIG. 2  is a diagram showing a sensing reference power control system in a display device according to embodiments of the present invention; 
         FIGS. 3 to 4  are detailed block diagrams of an electronic control device in a sensing reference power control system in a display device according to embodiments of the present invention; 
         FIG. 5  is a flowchart showing a method of controlling a sensing reference power by a sensing reference power control system in a display device according to embodiments of the present invention; 
         FIG. 6  is a diagram exemplarily indicating a sub-pixel structure of a display device according to embodiments of the present invention; 
         FIGS. 7 and 8  are layout diagrams of an analog-to-digital converter and a sensing line in a display device according to embodiments of the present invention; 
         FIG. 9  is an exemplary view implementing a sensing reference power control system in a display device according to embodiments of the present invention; 
         FIG. 10  is a diagram for explaining an abnormal sensing reference power and an error of sensing data when the sensing data is generated using the abnormal sensing reference power; 
         FIG. 11  is a diagram for explaining a block dim phenomenon generated from a display panel when an error occurs in the sensing data due to abnormal sensing reference power; 
         FIG. 12  is a diagram for explaining preventing of occurrence of an error in sensing data when the sensing data is generated using a sensing reference power normally generated by the control of a sensing reference power, according to embodiments of the present invention; and 
         FIG. 13  is a diagram for explaining that when sensing data is generated using a sensing reference power which is normally generated by the control of the sensing reference power according to embodiments of the present invention, an error in the sensing data is prevented and thereby a block dim phenomenon in a display panel is prevented. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In designating elements of the drawings by reference numerals, the same elements will be designated by the same reference numerals although they are shown in different drawings. Further, in the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. 
     In addition, terms, such as first, second, A, B, (a), (b) or the like may be used herein when describing components of the present invention. Each of these terminologies is not used to define an essence, order or sequence of a corresponding component but used merely to distinguish the corresponding component from other component(s). In the case that it is described that a certain structural element “is connected to”, “is coupled to”, or “is in contact with” another structural element, it should be interpreted that another structural element may “be connected to”, “be coupled to”, or “be in contact with” the structural elements as well as that the certain structural element is directly connected to or is in direct contact with another structural element. 
       FIG. 1  is a view showing a display device  100  according to embodiments of the present invention. 
     Referring to  FIG. 1 , the display device  100  according to the embodiments includes a display panel  110  in which a plurality of data lines and a plurality of gate lines are arranged, a data drive unit  120  for driving a plurality of data lines, a gate drive unit  130  for sequentially driving a plurality of gate lines, and a timing controller  140  for controlling the data drive unit  120  and the gate drive unit  130 . 
     In the display panel  110 , sub-pixels are located at every point where a plurality of data lines and a plurality of gate lines cross each other. 
     The timing controller  140  starts a scan according to a timing implemented in each frame, converts image data input from an interface in correspondence to a data signal form used by the data drive unit  120 , outputs the converted image data, and controls a data driving at a proper time in correspondence with the scan. 
     The timing controller  140  may output various control signals such as a Data Control Signal (DCS), a Gate Control Signal (GCS), and the like, in order to control the data drive unit  120  and the gate drive unit  130 . 
     The gate drive unit  130 , based on the control of the timing controller  140 , sequentially supplies a scan signal of On-voltage or Off-voltage to a plurality of gate lines and sequentially drives a plurality of gate lines. 
     The data drive unit  120 , based on the control of the timing controller  140 , stores the input image data in the memory (not shown), and when a particular gate line is open, the data drive unit  120  converts a corresponding video data (Data) into analog format data voltage (Vdata) and supplies the Vdata to the plurality of data lines and thus drives the plurality of data lines. 
     Referring to  FIG. 1 , the data drive unit  120  may include M (1 or more natural number) pieces of source driver integrated circuit (S-DIC: Source Driver IC, it may also be called a data driver integrated circuit (Data Driver IC), S-DIC # 1 , . . . , a S-DIC #M), and these M source driver integrated circuits (S-DIC # 1 , . . . , S-DIC # M) may be connected to the bonding pads on the display panel  110  by a tape automated bonding method (TAB) or a chip-on-glass (COG) method or may be formed directly on the display panel  110 , and in some cases, these M source drive integrated circuits may be formed by being integrated in the display panel  110 . 
     Referring to  FIG. 1 , each of the M source driver ICs (S-DIC # 1 , . . . , S-DIC #M) is implemented by a chip on film (COF) method, and one side and the other side of the source driver IC may be connected to the display panel  110  and the source printed circuit board (S-PCB)  150 , respectively. 
     The gate drive unit  130  may be positioned on only one side of the display panel  110  as illustrated in  FIG. 1  or may be divided into two and positioned on both sides of the display panel  110 , depending on a driving manner. 
     Referring to  FIG. 1 , the gate drive unit  130  may include N (N is a natural number greater than or equal to 2) gate drive integrated circuits (G-DIC: Gate Drive unit IC, G-DIC # 1 , . . . , G-DIC #N), and such a plurality of gate drive integrated circuits (G-DIC # 1 , . . . , G-DIC # N) may be connected to the bonding pads on the display panel  110  by a tape automated bonding method (TAB) or a chip-on-glass (COG) method or may be implemented by a Gate In Panel type GIP and formed directly on the display panel  110 , and in some cases, the gate driver integrated circuits may be formed by being integrated in the display panel  110 . 
     Referring to  FIG. 1 , the timing controller  140  may be located on a control printed circuit board  160  connected with a source printed circuit board  150  via a connection means  170  such as a flexible printed circuit (FPC) or a flexible flat cable (FFC) or the like. 
     The control printed circuit board  160  may further include the power management integrated circuit (PMIC, not shown), a gamma integrated circuit (Gamma IC, not shown) and the like. 
     The display device  100  schematically illustrated in  FIG. 1  may be one among a Liquid Crystal Display (LCD) device, a Plasma Display Panel (PDP) device, an Organic Light Emitting Diode (OLED) display device, etc. 
     Each of the sub-pixels formed on the aforementioned display panel  110  may include a circuit element such as a transistor, and may further include at least one capacitor, Organic Light Emitting Diode OLED, etc. according to a circuit design method, the type of the display device and the like. 
     Meanwhile, a plurality of sub-pixels is formed on the display panel  110  and a plurality of pixels P is defined. One pixel P may be configured by, as an example, three sub-pixels (a red sub-pixel, a green sub-pixel, and a blue sub-pixel) or four sub-pixels (a red sub-pixel, a white sub-pixel, a green sub-pixel, and a blue sub-pixel). 
     Meanwhile, the transistor included in the circuit elements in each sub-pixel has unique characteristic values of a threshold voltage, mobility, etc., and the unique characteristic values are changed depending on driving time. Accordingly, a deviation in the unique characteristic values between each of the transistors may occur. The deviation of the unique characteristic values between transistors in each of the sub-pixels becomes a factor which lowers the quality of the image by generating the luminance deviation between the sub-pixels. 
     To this end, the display device  100  according to embodiments of the present invention may provide a “compensation function” for compensating for the luminance deviation between the sub-pixels. 
     The display device  100  according to the embodiment of the present invention includes a structure for sensing unique characteristic values of the transistors included in the circuit in the sub-pixels in order to provide the compensation function. 
     To this end, for the display panel  110 , the “sensing line SL”, connected to the circuit in the sub-pixels, may be disposed, one to one, at each column of one sub-pixel or two or more sub-pixels. 
     These sensing lines may be arranged, as an example, in parallel with the data line. 
     In addition, one sensing line may also exist for each column of a single sub-pixel, one sensing line may exist for each column of two or more sub-pixels, and one sensing line may exist for each of the pixel columns. 
     For example, one sensing line may exist for each column of four sub-pixels (a red sub-pixel column, a white sub-pixel column, a green sub-pixel column, and a blue sub-pixel column), that is, one sensing line may exist for each pixel column. 
     Meanwhile, in order to provide a compensation function, the display device  100  according to an embodiment may include a “sensing unit” that is connected to one or more sensing lines SL and generates sensing data by converting a voltage sensed through the sensing line SL to a digital value, in addition to the configuration of the “sensing line SL”, and a “compensation unit” that converts data to be supplied to the sub-pixels for the luminance deviation compensation between the sub-pixels on the basis of the sensing data sensed and output by the sensing unit. 
     Hereinafter, the above-mentioned sensing unit is also referred to as an analog-to-digital converter (ADC) and is described, for short, as “ADC”. 
     The analog-to-digital converter (ADC) may be located in any place of the display device  100 , and as an example, one ADC may be included inside each of the source driver integrated circuits (S-DICs). 
     Further, the above-mentioned compensation unit may be located in any place inside the display device  100 . However, as an example, the compensation unit may be included inside the timing controller  140 . 
     Meanwhile, an analog-to-digital converter (ADC) which corresponds to the sensing unit requires a power serving as a reference when converting the analog voltage values that are sensed via a sensing line SL to digital values. The power required as a reference for the analog to digital conversion may be referred to as “conversion reference power” or “sensing reference power SRP. 
     The sensing reference power (conversion reference power) may fluctuate due to a variety of noise and another power source or other signals generated inside or outside of the display device  100 . That is, a voltage (sensing reference voltage or the conversion reference voltage) of the sensing reference power (conversion reference power) is not fixed and it may momentarily or intermittently vary due to noise, another power source, other signals or the like. 
     Thus, when the analog-to-digital converter (ADC) converts the sensed analog voltage value to a digital value, if the sensing reference power SRP serving as a reference fluctuates the sensed analog voltage value may be converted to the erroneous digital value and thus an error occurs due to the sensing data. 
     In this case, since the timing controller  140  corresponding to the compensation unit calculates the data compensation amount based on the erroneous sensing data, an error also occurs due to the calculated data compensation amount. Therefore, since the luminance deviation compensation is not performed suitably in sub-pixel column(s) corresponding to the analog-to-digital converter (ADC) for generating the error from the sensing data, the “block dim phenomenon” may occur along the sub-pixel column direction (e.g., vertical direction). 
     Thus, the embodiments of the present invention may sense whether the sensing reference power is normal and provides a sensing reference power control function so that the analog-to-digital converter (ADC) may use the normal sensing reference power (conversion reference power). 
     Hereinafter, a sensing reference power control function according to embodiments of the present invention will be illustrated in more detail. 
       FIG. 2  is a diagram showing a sensing reference power control system in a display device  100  according to embodiments of the present invention. 
     Referring to  FIG. 2 , the sensing reference power control system (or the conversion reference power supply control system) in the display device  100  according to embodiments of the present invention includes an analog-to-digital converter  210  for converting an analog voltage value into a digital value on the basis of the conversion reference voltage (the sensing reference voltage SRP), and a power control device  220  that generates a conversion reference voltage (sensing reference voltage SRP) and outputs the conversion reference voltage (sensing reference voltage SRP) to the analog-to-digital converter  210 , wherein the power control device  220  generates a conversion reference power (sensing reference voltage SRP) within a predetermined range (from the minimum voltage to maximum voltage) and outputs the conversion reference power (sensing reference voltage SRP) within the predetermined range to the analog-to-digital converter  210 . 
     According to the above description, the analog-to-digital converter  210 , when converting an analog voltage value into a digital value, converts analog voltage values to digital values using the sensing reference power SRP within a predetermined range (the range from the minimum voltage to the maximum voltage) which may ensure conversion accuracy and thus it is possible to improve the accuracy of the analog to digital conversion. 
     Meanwhile, the conversion reference power control function described above may be applied to other general analog to digital conversions as well as an analog to digital conversion for a compensation function. 
       FIGS. 3 to 4  are detailed block diagrams of an electronic control device in a sensing reference power control system in a display device  100  according to embodiments of the present invention. 
     Referring to  FIG. 3 , a power control device  220 , which generates a sensing reference power SRP within a predetermined range (the range from the minimum voltage to the maximum voltage) and outputs the SRP to the analog-to-digital converter  210 , includes a power generator  310 , and a power controller  320 . 
     The power generator  310  generates and outputs a sensing reference power SRP which serves as a reference when an analog-to-digital converter  210  converts the voltage at the sensing node (N 1  or N 4  or any node on the sensing line SL, in  FIG. 6 ) in the sub-pixels on the display panel  110  to a digital value. 
     The power controller  320  determines whether the voltage (sensing reference voltage) of the sensing reference power SRP input from the power generator  310  is within a predetermined voltage range, and when the voltage (sensing reference voltage) of the sensing reference power SRP input from the power generator  310  is within a predetermined voltage range, the power controller  320  outputs the sensing reference power SRP input from the power generator  310  to the analog-to-digital converter  210 , and when the voltage of the sensing reference power input from the power generator  310  is out of the predetermined voltage range, the power controller  320  controls the power generator  310  to regenerate the sensing reference power SRP. 
     According to the above description, it is possible to provide a mechanism capable of regenerating the sensing reference power SRP and detailed configurations of the power control device  220  therefor so that the analog-to-digital converter  210 , when converting an analog voltage value into a digital value, may perform an accurate analog to digital conversion using the sensing reference power SRP within a predetermined range (the range from the minimum voltage to the maximum voltage) guaranteeing conversion accuracy. 
     Hereinafter, the sensing reference power control system briefly described above will be described in more detail in conjunction with the compensation system. 
     Referring to  FIG. 3 , an analog-to-digital converter  210  corresponding to the compensation unit in the compensation system is connected to a sensing line SL connected to the sensing node within the sub-pixel on the display panel  110 , and outputs the sensing data after converting the voltage of the sensing node that is sensed through the sensing line SL, based on the voltage of the sensing reference power SRP, to a digital value. 
     Referring to  FIG. 3 , the timing controller  140  corresponding to the compensation unit in the compensation system is connected to the analog-to-digital converter  210  through sensing data transmission lines SDTL (shown as Sensing Data in  FIG. 3 ), and calculates a data compensation amount based on the sensing data input through the sensing data transmission line SDTL to store in a memory  330 . 
     Thus, the data compensation amount stored in the memory  330  is utilized when driving a video in the future and the sub-pixel luminance deviation compensation is actually performed. 
     That is, when transmitting data which will be supplied to each sub-pixel to the source driver integrated circuits (S-DIC # 1 , . . . , S-DIC #M) in order to drive the video, the timing controller  140  changes the data to be transmitted and transmits the changed data to the source driver integrated circuits (S-DIC # 1 , . . . , S-DIC #M) with reference to the data compensation amount stored in the memory  330 . The source driver ICs (S-DIC # 1 , . . . , S-DIC #M) converts, using an internal digital to analog converter (DAC, not shown), the data received by itself to an analog data voltage, and outputs the converted data voltage to the corresponding data line. Thus, the luminance deviations of the sub-pixels are compensated for. 
     Referring to  FIG. 3 , the power generator  310  generates or regenerates the sensing reference power SRP that serves as a reference when the analog-to-digital converter  210  converts a voltage at the sensing node to a digital value and outputs the generated or regenerated SRP. 
     Referring to  FIG. 3 , when the sensing reference power SRP is input from the power generator  310 , the power controller  320  outputs the sensing reference power SRP input from the power generator  310  to the analog-to-digital converter  210  or controls the power generator  310  to regenerate the sensing reference power SRP. 
     According to the above description, it is possible to provide a mechanism capable of regenerating the sensing reference power SRP and a power generator  310  and a power control device  220  therefor so that the analog-to-digital converter  210  may perform, when converting an analog voltage value into a digital value, an accurate analog to digital conversion using the sensing reference power SRP within a predetermined range (the range from the minimum voltage to the maximum voltage) guaranteeing conversion accuracy. 
     Referring to  FIG. 3 , the timing controller  140  outputs, according to the sensing timing for the compensation function, the power generation control signal (PGC) that generates the sensing reference power SRP which serves as a reference at the time of sensing. 
     Accordingly, when a power generation control signal PGC is first input from the timing controller  140 , the power generator  310  generates a sensing reference power SRP and outputs the generated SRP to the power controller  320 . 
     The power controller  320  determines whether the voltage of the sensing reference power SRP output from the power generator  310  is within a predetermined voltage range, and determines whether the sensing reference power SRP output from the power generator  310  is normal or abnormal. 
     Referring to  FIG. 3 , when the sensing reference power SRP output from the power generator  310  is determined to be normal, the power controller  320  outputs the sensing reference power SRP output from the power generator  310  to the analog-to-digital converter  210 , and when the sensing reference power SRP output from the power generator  310  is determined to be abnormal, the power controller  320  outputs an Abnormal SRP Detection Signal ASRPDS meaning that the sensing reference power SRP output from the power generator  310  is abnormal to the timing controller  140 . 
     Referring to  FIG. 3 , when the Abnormal SRP Detection Signal ASRPDS is received from the power controller  320 , the timing controller  140  outputs a power re-generation control signal PRGC to the power generator  310 . 
     Accordingly, when the power re-generation control signal PRGC is input from the timing controller  140 , the power generator  310  re-generates the sensing reference power SRP and re-outputs the regenerated SRP to the power controller  320 . 
     By repeating the process as described above, the normal sensing reference power SRP from the power controller  320  is finally transmitted to the analog-to-digital converter  210 . 
     According to the above description, it is possible to provide an efficient signaling system for a re-generation mechanism of the sensing reference power SRP so as to generate the sensing reference power SRP that can become an accurate reference, in order for the analog-to-digital converter  210  to accurately convert an analog voltage value into a digital value, and transmit the generated sensing reference power SRP to the analog-to-digital converter  210 . 
     The above-described power controller  320  determines whether there is an abnormality in the sensing reference power SRP generated by the power generator  310 , and determines whether to output to the analog-to-digital converter  210  or determines whether to regenerate the sensing reference power SRP. 
     Referring to  FIG. 4 , the power controller  320  will be described in more detail. 
     Referring to  FIG. 4 , the power controller  320  includes comparators  310  and  320  for comparing the voltage of the sensing reference power SRP input from the power generator  310  with a predetermined maximum voltage SRP_MAX and minimum voltage SRP_MIN, respectively; and a determination unit  430  for outputting, depending on the result of the comparison, the abnormal sensing reference power detection signal ASRPDS 1  or ASRPDS 2  to the timing controller  140 , when the voltage of the sensing reference power SRP input from the power generator  310  exceeds the maximum voltage SRP_MAX or is less than the minimum voltage SRP_MIN, that is, if the voltage of the sensing reference power input SRP input from the power generator  310  is out of the predetermined voltage range, and outputting the sensing reference power input SRP input from the power generator  310  to the analog-to-digital converter  210 , when the voltage of the sensing reference power SRP input from the power generator  310  is greater than or equal to the minimum voltage SRP_MIN or less than or equal to the maximum voltage SRP_MAX, that is, if the voltage of the sensing reference power SRP input from the power generator  310  is within the predetermined voltage range. 
     Referring to  FIG. 4 , the timing controller  140  outputs a power regeneration control signal PRGC to the power generator  310  depending on the abnormal sensing reference power detection signal ASRPDS 1  or ASRPDS 2  output from the determination unit  430  of the power controller  320 . 
     Accordingly, the power generator  310  re-generates and re-outputs the sensing reference power SRP. 
     According to the above description, it is possible to provide a detailed configuration of the power controller  320  corresponding to the important control structure, which determines whether there is an abnormality in the sensing reference power SRP generated by the power generator  310  and decides whether to output the sensing reference power to the analog-to-digital converter  210  or decides whether to regenerate the sensing reference power, so as to generate the sensing reference power SRP that can become an accurate reference, in order for the analog-to-digital converter  210  to accurately convert an analog voltage value into a digital value, and transmit the sensing reference power SRP to the analog-to-digital converter  210 . 
     Hereinafter, the above-described sensing reference power control method will be briefly described again with reference to  FIG. 5 . 
       FIG. 5  is a flowchart showing a method for controlling a sensing reference power SRP by a sensing reference power control system in a display device  100  according to embodiments of the present invention. 
     Referring to  FIG. 5 , in step S 510 , the power generator  310  generates a sensing reference power SRP depending on a power generation control signal PGC input from the timing controller  140 . 
     Hereinafter, in step S 520 , the power controller  320  determines whether the sensing reference power SRP input from the power generator  310  is abnormal. 
     As a result of the determination in step S 520 , when the sensing reference power SRP input from the power generator  310  is determined to be normal, that is, if the sensing reference power SRP input from the power generator  310  is within the normal range (which is greater than or equal to the minimum voltage and less than or equal to the maximum voltage), in step S 560 , the power controller  320  finally outputs the normal sensing reference signal SRP to the analog-to-digital converter  210 . 
     As a result of the determination in step S 520 , when the sensing reference power SRP input from the power generator  310  is determined to be abnormal, that is, if the sensing reference power SRP input from the power generator  310  is out of the normal range (the range which exceeds the maximum voltage or is less than the minimum voltage), in step S 530 , the power controller  320  increases the count value (COUNT) by one. The count value (COUNT) represents the number of times the sensing reference power SRP input from the power generator  310  is determined to be abnormal. 
     After the S 530  step, the power controller  320  determines whether the count value (COUNT) exceeds (or is greater than or equals to) a predetermined threshold count value (e.g., three) in step S 540 . 
     Here, the threshold count value (e.g., three) is information on determining whether the corresponding action on the abnormal situations of the sensing reference power SRP is required. The count value (COUNT) increases by zero, one, or two, and when the sensing reference power is determined to be normal, the count value can be reset back to zero. 
     As a determination result of step S 540 , when it is determined that the count value (COUNT) is less than or equal to a predetermined threshold count values (e.g., three), that is, if it is determined that the corresponding measurements on the abnormal situations of the sensing reference power SRP are still not necessary, the power controller  320  outputs the abnormal sensing reference power detection signal ASRPDP to the timing controller  140 . 
     The timing controller  140  outputs the power re-generation control signal PRGC to the power generator  310 . 
     Accordingly, the power generator  310  re-generates the sensing reference power SRP in step S 510 . 
     Hereinafter, by repeating the process described above, in step S 560 , the power controller  320  finally outputs the normal sensing reference signal SRP to the analog-to-digital converter  210 . 
     As a determination result of step S 540 , when it is determined that the count value (COUNT) exceeds a predetermined threshold count values (e.g., three), that is, if it is determined that the corresponding measures on the abnormal situations of the sensing reference power SRP is required, the power controller  320  or the timing controller  140  performs a corresponding process in step S 550 . 
     As an example, when the number of times (COUNT) of the abnormal situation occurrence of the sensing reference power SRP input from the power generator  310  is larger than or equal to a predetermined number (a threshold count value, for example, three or four times or possibly larger values than three or four), the power controller  320  or a timing controller  140  may output the control signal for progressing to a power-off process or a display device reset process to the power management unit (not shown). 
     As described above, when the abnormal situation of the sensing reference power SRP has continuously occurred a predetermined number of times or more, the display device  100  is powered off or reset and thus it is possible to turn the power on and induce the sensing reference power SRP to be under normal situations. These response measures can be adapted to a case where an abnormal situation of the sensing reference power SRP is temporarily or sporadically generated by a signal or a noise. 
     As another example, when the number of times of the abnormal situation occurrence of the sensing reference power SRP input from the power generator  310  is larger than or equal to a predetermined number (a threshold count value, three or four times or possibly bigger values than 3 or 4), the power controller  320  or the timing controller  140  may stop the compensation process. 
     As described above, when the abnormal situations of the sensing reference power SRP input from the power generator  310  has continuously occurred a predetermined number of times or more, the power controller  320  or a timing controller  140  may prevent the image quality from being degraded due to the error occurring due to the sensing data by not performing the compensation process using the sensing reference power SRP. The above described measure is a response measure that can be taken when the case of not performing the compensation process is more advantageous in terms of the image quality as compared to the case of obtaining the sensing data using an abnormal sensing reference power and proceeding the compensation process therefrom. 
     Meanwhile, the number of times that is referenced in order to power off the display device  100  or reset the display device  100  and the number of times that is referenced to determine the timing for stopping the compensation process are the same value but also may be set to be different from each other. 
     For example, the number of times (a second threshold count value) to be referenced to determine the timing for stopping the compensation process can be set to be larger than the number of times (a first threshold count value) that is referenced in order to determine the timing for cutting off the power supply of the display device  100  or resetting the display device  100 . 
     In other words, when the number of times (COUNT) of the abnormal situation occurrence of the sensing reference power SRP is greater than or equal to (or exceeds) the first threshold count value, the timing controller  140  or the power controller  320  outputs a control signal for cutting-off the power of the display device  100  and resetting the display device  100 . At this time, the number of times (COUNT) the abnormal situation of the sensing reference power SRP has occurred is not reset. 
     The timing controller  140  or the power controller  320  determines, after the display device  100  is powered on again, whether the abnormal situation of the sensing reference power SRP is maintained or has been restored to the normal situation. When it is determined that the occurred abnormal situation of the sensing reference power SRP is still maintained, the timing controller  140  or the power controller  320  may increase, once more, the number of times (COUNT) by which the abnormal situation of the sensing reference power SRP has occurred. Further, when the number of times (COUNT) becomes larger than or equal to (or exceeds) the second threshold count value, the timing controller  140  or the power controller  320  may stop the compensation process. 
     Thereafter, the timing controller  140  or the power controller  320  may output a control signal to display a message indicating that the display device  100  needs to be repaired. 
     Each of the steps of the flowchart illustrated in  FIG. 5  may be changed, such as modified, integrated or separated within the range that does not change the basic technical concept of the embodiments. 
     Meanwhile, the sensing reference power control described above is a control of the sensing reference power, which serves as a reference when the analog-to-digital converter  210  senses a voltage at the sensing node within the sub-pixel via a sensing line SL and converts the sensed voltage into a digital value, to have a desired fixed voltage. 
     In the following, referring to  FIGS. 6 and 7 , a description will be given on a sub-pixel structure in which sensing is performed by the analog-to-digital converter  210  and a sensing line arrangement structure associated therewith. 
     However, the display device  100  according to embodiments of the present invention can be a different type such as a liquid crystal display device and an organic light emitting display device, and in the following description, the sub-pixel structure and the sensing line arrangement structure for the organic light emitting display device will be explained as an example. 
       FIG. 6  is a diagram exemplarily indicating a sub-pixel structure of a display device  100  according to embodiments of the present invention. 
     Referring to  FIG. 6 , each of the plurality of sub-pixels arranged on the display panel  110  of the display device  100  according to embodiments of the present invention includes organic light-emitting diodes OLED and circuits for driving the same. 
     The organic light emitting diode drive circuit within each sub-pixel may include at least one transistor and at least one capacitor. Further, the organic light emitting diode drive circuit in each sub-pixel may further include a circuit element for the luminance deviation compensation. 
       FIG. 6  is an equivalent circuit diagram for the sub-pixels with 3T (Transistor) 1C (Capacitor) structure including the organic light emitting diode drive circuit, three transistors (T 1 , T 2 , T 3 ) and one capacitor C 1 . 
     Referring to  FIG. 6 , the first transistor T 1  among the three transistors (T 1 , T 2 , T 3 ) is a driving transistor for driving the organic Light Emitting Diode (OLED) and is connected between the driving voltage line DVL or the pattern associated with the driving voltage line DVL and the organic light emitting diode OLED. 
     Referring to  FIG. 6 , the second transistor T 2  among the three transistors (T 1 , T 2 , T 3 ) is a switching transistor which turns on or turns off depending on the presence or absence of a scan signal through the first gate line GL, and when turned-on, turns on or off the first transistor T 1  by applying a voltage at a second node N 2  (gate node) of the first transistor T 1  corresponding to the driving transistor, and the second transistor T 2  is connected between the data line DL for supplying a data voltage Vdata and the second node N 2  of the first transistor T 1 . 
     Referring to  FIG. 6 , the first node N 1  of the first transistor T 1  is a drain node or a source node and is a_node connected to the first electrode (e.g., an anode electrode or a cathode electrode) of the organic light emitting diode OLED. Here, the second electrode (e.g., a cathode electrode or an anode electrode) of the organic Light Emitting Diode (OLED) is applied with the base voltage EVSS. The second node N 2  of the first transistor T 1  is a gate node, and is applied with data voltage Vdata supplied from the data line DL through the turned-on second transistor T 2 . The third node N 3  of the first transistor T 1  is a source node or a drain node, and is applied with a driving voltage EVDD supplied from the driving voltage line DVL or the pattern connected thereto. 
     Referring to the  FIG. 6 , the third transistor T 3  among the three transistors (T 1 , T 2 , T 3 ) is connected between a fourth node N 4  in which the reference voltage Vref is supplied from the reference voltage line RVL (shown in  FIG. 6  as sensing line SL) or a pattern connected thereto and the first node N 1  of the first transistor T 1 . 
     Here, an end portion of the reference voltage line RVL which is electrically connected with the fourth node N 4  is connected to a switch SW. The switch SW selectively connects the reference voltage line RVL to either a supplying point of the reference voltage Vref or the analog-to-digital converter  210 . 
     The third transistor T 3  is a sensing transistor that is involved in compensating for the luminance deviation of the sub-pixel, and is turned on or turned off depending on whether a sense signal that is a kind of scan signal from the second gate line GL′ is supplied or not, and when turned-on, the third transistor T 3  serves to apply the reference voltage Vref to the first node N 1  of the first transistor T 1  or serves to have the voltage at the first node N 1  of the first transistor T 1  sensed by the analog-to-digital converter  210  through the reference voltage line RVL. Here, the reference voltage line RVL corresponds to the sensing line SL. 
     The analog-to-digital converter  210  senses the voltage at the sensing node based on the sensing reference power SRP and converts the sensed voltage to a digital value to generate sensing data, and transmits the generated sensing data to the timing controller  140 . 
     Here, the sensing node at which the voltage is sensed by the analog-to-digital converter  210  may be any node (including N 4 ) on the sensing line SL, and may be the first node N 1  of the first transistor T 1  when the third transistor T 3  is turned on at the voltage sensing time point. 
     Further, the voltage sensed by the analog-to-digital converter  210  is a voltage for identifying unique characteristic values of the sub-pixels SP or the change (deviation) of the unique characteristic values. 
     Here, the unique characteristic value for the sub-pixels SP corresponds to, as an example, the unique characteristic value (the threshold voltage or mobility) of the first transistor T 1  which is the drive transistor within the sub-pixel SP, or corresponds to the unique characteristic value (the threshold voltage) of the organic light-emitting diode OLED. 
     The timing controller  140  receives the sensing data, and, on the basis of the sensed data, performs a compensation process which compensates for the deviation on the unique characteristic values (the threshold voltage, mobility, etc.) of the first transistor T 1  corresponding to the driving transistor in each sub-pixel, or the unique characteristic values (the threshold voltage, etc.) of the organic light-emitting diode OLED. Here, for the compensation process, the data compensation amount which is compensated for the deviation of the unique characteristic value of the first transistor T 1  or the unique characteristic value of the organic Light Emitting Diode (OLED) is determined, and the data which will be supplied to the corresponding sub-pixel is changed depending on the determined data compensation amount and then the changed data is supplied to the source driver  120 . 
     Referring to  FIG. 6 , one capacitor C 1  is connected between the second node N 2  and the third node N 3  of the first transistor T 1  corresponding to the driving transistor, and the capacitor C 1  serves to maintain a constant voltage for a certain period of time (for example, a frame time). 
     Referring to  FIG. 6 , the change of timing of various signals (EVDD, EVSS, Vdata, Scan Signal, Sense Signal, etc.) necessary to drive the 3T1C structured sub-pixels is controlled by the timing controller  140 . 
       FIGS. 7 and 8  are layout diagrams of an analog-to-digital converter  210  and a sensing line SL in a display device  100  according to embodiments of the present invention. 
     Referring to  FIG. 7 , a single sensing line SL may be disposed at each column of one sub-pixel or at each column of two or more sub-pixels. 
     Alternatively, as shown in  FIG. 8 , a case is exemplified where one pixel is constituted by four sub-pixels, and one sensing line SL may be disposed at each column of one pixel column. The sensing line SL is connected with the four sub-pixels at the same time. 
     Referring to  FIGS. 7 and 8 , one analog-to-digital converter  210  is connected to one or more sensing lines SL and is included in a single source driver IC. 
     That is, one source driver integrated circuit (S-DIC) may include one analog-to-digital converter  210 , and one analog-to-digital converter  210  may include a plurality of channels connected to a plurality of sensing lines SL. 
     According to the description above, in order to compensate for sub-pixel luminance deviation, it is possible to provide a sensing structure capable of sensing the unique characteristic value of the first transistor T 1  corresponding to the driving transistor in each sub-pixel or the unique characteristic value of the organic light emitting diode OLED. 
       FIG. 9  is an exemplary view implementing a sensing reference power control system in a display device  100  according to the embodiments of the present invention. 
     As mentioned above, the analog-to-digital converter  210  which corresponds to the sensing unit may be located in any place of the display device  100 , and as an example, the ADC  210  may be included inside each of the source driver integrated circuit (S-DIC). Further, the compensation unit may be located in any place inside the display device  100 , however, as an example, the compensation unit may be included inside the timing controller  140 . 
       FIG. 9  is an implementation example of a case where the analog-to-digital converter  210  corresponding to the sensing unit is included inside the source driver IC (S-DIC), and the compensation unit is included in the inside of the timing controller  140 . 
     Referring to  FIG. 9 , each of M source driver integrated circuits (S-DIC # 1 , . . . , S-DIC #M) has a built-in analog-to-digital converter  210  and is connected to the timing controller  140  via the sensing data transmission line SDTL. Here, the sensing data transmission line SDTL may be, as an example, a low voltage differential signaling (LVDS) method-based transmission line. 
     Referring to  FIG. 9 , a timing controller  140  including a compensation unit may be connected to the power generator  310  via a signal communication line SCL. Here, the signal communication line SCL may be an inter integrated circuit (I2C) protocol-based communication line for accessing the on-board chip or an external memory. 
     The power generator  310  which is connected with the timing controller  140  via a signal communication line SCL and generates a sensing reference power SRP may be, as an example, a gamma-integrated circuit (Gamma IC). 
     As described above, it is possible for the power generator  310  to generate the sensing reference power SRP to be implemented by the gamma-integrated circuit corresponding to the existing configuration required for video driving and thus enabling to reduce the number of components. 
     Referring to  FIG. 9 , the power generator  310  is connected to a power controller  320  via a first power supply line PL 1  and thus may transmit the sensing reference power to the power controller  320 . 
     Further, the power controller  320  is connected to each of M source driver integrated circuits (S-DIC # 1 , . . . , S-DIC #M) and may transmit the sensing reference power to the analog-to-digital converter  210  incorporated in each of M source driver integrated circuits (S-DIC # 1 , . . . , S-DIC #M). 
     The power controller  320  may be connected to the timing controller  140  via a detection signal line DSL. Thus, when the regeneration of the sensing reference power is required, the power controller  320  may transmit the abnormal sensing reference power detection signal ASRPDS to the timing controller  140 . 
     On the other hand, the power controller  320  may be implemented in another single integrated circuit, or it may be implemented as a circuit on a source printed circuit board  160  by using an integrated circuit implementing the comparators  410  and  420  and a Metal Oxide Silicon Field Effect Transistor (MOSFET). 
     In the following, referring to  FIGS. 10 to 13 , a description will be given of the block dim phenomenon preventing effect due to the sensing reference power control according to embodiments of the present invention. 
       FIG. 10  is a diagram for explaining an abnormal Sensing Reference Power (SRP) and an error of sensing data generated using the abnormal SRP.  FIG. 11  is a diagram for explaining a block dim phenomenon generated from a display panel  110  when an error occurs from the sensing data due to the abnormal sensing reference power SRP. 
     Referring to  FIG. 10 , in a case where the sensing reference voltage control according to embodiments of the present invention is not used, when the analog-to-digital converter ADC converts the sensed analog voltage value to a digital value, the sensing reference power SRP serving as a reference can fluctuate. That is, the voltage of the sensing reference power SRP is not fixed to a desired value and may change due to the noise or other signals or the like. 
     In such a case, when the analog-to-digital converter ADC converts the sensed analog voltage value into a digital value, even the converted digital value is not accurate. 
     Thus, inaccurate sensing data is generated by the analog-to-digital converter ADC. 
     Due to the error of the sensing data, the data compensation amount which is calculated by the timing controller  140  corresponding to the compensation unit is also inaccurate, and as a result, the sub-pixel luminance deviation compensation is not properly done and which leads to a poor image quality. 
     Referring to  FIG. 11 , the “block dim phenomenon” may occur in regions  810  and  820  corresponding to the columns of the sub-pixel which receives the data voltage from the source driver integrated circuits (in the case of  FIG. 11 , S-DIC # 1  and S-DIC #K) including the analog-to-digital converter ADC which generated the error of the sensing data and thus leads to a poor image quality. 
       FIG. 12  is a diagram for explaining preventing of occurrence of errors in sensing data when generating the sensing data using the sensing reference power SRP which is normally generated by the control of a sensing reference power SRP according to embodiments of the present invention.  FIG. 13  is a diagram for explaining that when generating sensing data using the sensing reference power SRP which is normally generated by the control of a sensing reference power SRP according to embodiments of the present invention, an error in the sensing data is prevented and thereby a block dim phenomenon in a display panel is prevented. 
     Referring to  FIG. 12 , in a case where a sensing reference voltage control according to embodiments of the present invention is used, when the analog-to-digital converter  210  converts the sensed analog voltage value to a digital value, the sensing reference power SRP serving as a reference can be accurately generated without fluctuation. That is, despite the influence of noise or other signals, the voltage of the sensing reference power SRP is generated at a desired fixed value. 
     Therefore, the analog-to-digital converter ADC may convert the sensed analog voltage value to an accurate digital value and accurately generate the sensing data that can accurately compensate for the sub-pixel luminance deviation. 
     Therefore, the timing controller  140  corresponding to the compensation unit can accurately calculate the data compensation amount based on the accurate sensing data. As a result, the sub-pixel luminance deviation compensation is performed appropriately, and as shown in  FIG. 13 , the poor image quality such as the block dim phenomenon can be prevented. 
     According to embodiments of the present invention as described above, when generating sensing data serving as a basis for the sub-pixel luminance deviation compensation, since the sensing reference power serving as a reference when converting the sensed analog voltage value into a digital value fluctuates, a problem of a decrease in the unexpected image quality such as a block dim phenomenon along the vertical direction, due to the sub-pixel luminance deviation compensation process, is likely to occur and a solution therefor can be provided. 
     Further, according to embodiments of the present invention, provide are a display device  100  and a power control device  220  capable of preventing the degradation of image quality that may occur unexpectedly by performing the sub-pixel luminance deviation compensation. 
     Furthermore, according to embodiments of the present invention, provided are a display device  100  and a power control device  220  capable of acquiring accurate sensing data by exactly generating and providing, as required, sensing reference power serving as a reference when converting analog voltage values sensed at the sub-pixels into digital values and accordingly performing an accurate sub-pixel luminance deviation compensation. 
     The above description and the accompanying drawings provide an example of the technical idea of the present invention for illustrative purposes only. Those having ordinary knowledge in the technical field, to which the present invention pertains, will appreciate that various modifications and changes in form, such as combination, separation, substitution, and change of a configuration, are possible without departing from the essential features of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate the scope of the technical idea of the present invention, and the scope of the present invention is not limited by the embodiment. The scope of the present invention shall be construed on the basis of the accompanying claims in such a manner that all of the technical ideas included within the scope equivalent to the claims belong to the present invention.