Patent Publication Number: US-2023162670-A1

Title: Display device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. § 119 to Korean Patent Application No. 10-2021-0160527 filed on Nov. 19, 2021 in the Korean Intellectual Property Office (KIPO), the disclosure of which is incorporated by reference herein in its entirety. 
     1. Technical Field 
     Example embodiments of the present disclosure relate generally to a display device. More particularly, example embodiments of the present disclosure relate to a display device capable of measuring a temperature of a display panel. 
     2. Description of the Related Art 
     In general, when current flows through pixels included in a display panel as a display device performs a display operation, a temperature of each of the pixels may increase. Such a temperature increase may change the characteristics of each of the pixels, which eventually results in an afterimage on the display panel. To prevent afterimages due to temperature increases in the pixels, the display device may perform a technique of temperature afterimage compensation by compensating for image data that is to be applied to the pixels (or pixel blocks) according to the temperature of each of the pixels (or an average temperature of each of the pixel blocks). However, to perform the temperature afterimage compensation, the display device has to accurately identify the temperature of each of the pixels (or the average temperature of each of the pixel blocks). 
     To accomplish this, a conventional display device may include a temperature sensor mounted on a rear surface of a display panel to measure temperatures of all pixels (or average temperatures of all pixel blocks) or measure temperatures of some pixels (or average temperatures of some pixel blocks), and predict temperatures of the remaining pixels (or average temperatures of the remaining pixel blocks) through interpolation. However, since this display device includes the temperature sensor on the rear surface of the display panel, a manufacturing cost of the display device may be increased, and there may be a limitation as to how small the display device can be made. 
     Another conventional display device may employ a technique of accumulating image data applied to each of pixels (or each of pixel blocks) while a display operation is performed, and predicting a temperature of each of the pixels (or an average temperature of each of the pixel blocks) based on the accumulated image data. However, since the technique does not reflect a characteristic deviation between display panels (e.g., the same products), a characteristic deviation between pixels within the display panel, and an external environment temperature at which the display panel operates, the temperature of each of the pixels (or the average temperature of each of the pixel blocks) may not be accurately identified. 
     SUMMARY 
     Example embodiments of the present disclosure provide a display device that does not include a temperature sensor so that it can be manufactured at a low cost and in a small size. In addition, the display device reflects all of a characteristic deviation between display panels, a characteristic deviation between pixels within the display panel, and an external environment temperature at which the display panel operates to accurately identify temperatures of the pixels, thereby enabling temperature afterimage compensation to be accurately performed on image data that is to be applied to the pixels. 
     Example embodiments of the present disclosure also provide a display device that does not include a temperature sensor so that it can be manufactured at a low cost and in a small size. In addition, the display device reflects all of a characteristic deviation between display panels, a characteristic deviation between pixels within the display panel, and an external environment temperature at which the display panel operates to accurately identify temperatures of pixel blocks, thereby enabling temperature afterimage compensation to be accurately performed on image data that is to be applied to the pixel blocks. 
     According to example embodiments of the present disclosure, there is provided a display device including: a display panel including a plurality of pixels; a display panel driver configured to drive the display panel; a memory device configured to store a reference current-temperature model that is set for the display panel, a global offset of the display panel, which is calculated based on the reference current-temperature model in a manufacturing stage of the display panel, and a local offset of the display panel, which is calculated based on a characteristic difference between the pixels in the manufacturing stage; and a panel temperature determiner configured to measure sensing currents flowing through the pixels when a temperature sensing voltage is applied to the pixels, calculate correction sensing currents by applying the global offset and the local offset to the sensing currents, and determine temperatures of the pixels by substituting the correction sensing currents into the reference current-temperature model. 
     The display device may further include a temperature afterimage compensator configured to perform temperature afterimage compensation on image data that is to be applied to the pixels based on the temperatures of the pixels. 
     In the manufacturing stage, an average temperature of the display panel is measured by a temperature sensing device. 
     In the manufacturing stage, initial sensing currents flowing through the pixels when the temperature sensing voltage is applied to the pixels are measured, an average of the initial sensing currents is calculated, and a difference between a current mapped to the average temperature in the reference current-temperature model and the average of the initial sensing currents is determined as the global offset. 
     In the manufacturing stage, initial sensing currents flowing through the pixels when the temperature sensing voltage is applied to the pixels are measured, an average of the initial sensing currents is calculated, and a difference between each of the initial sensing currents and the average of the initial sensing currents is determined as the local offset. 
     A frame in which the display panel operates includes an active period and a vertical blank period, and the panel temperature determiner performs a sensing current measurement operation of measuring the sensing currents during the vertical blank period. 
     The panel temperature determiner performs the sensing current measurement operation for one pixel row during the vertical blank period. 
     The panel temperature determiner does not perform the sensing current measurement operation during the vertical blank period in a preset low gray level frame. 
     The panel temperature determiner determines the frame as the preset low gray level frame when a maximum gray level of image data of the frame is less than a reference gray level, determines the frame as the preset low gray level frame when a minimum gray level of the image data of the frame is less than the reference gray level, or determines the frame as the preset low gray level frame when an average gray level of the image data of the frame is less than the reference gray level. 
     The panel temperature determiner performs a panel temperature determination operation of determining the temperatures of the pixels after the sensing current measurement operation for all of the pixels is completed. 
     According to example embodiments of the present disclosure, there is provided a display device including: a display panel including a plurality of pixels, which are grouped into pixel blocks; a display panel driver configured to drive the display panel; a memory device configured to store a reference current-temperature model that is set for the display panel, a global offset of the display panel, which is calculated based on the reference current-temperature model in a manufacturing stage of the display panel, and a local offset of the display panel, which is calculated based on a characteristic difference between the pixel blocks in the manufacturing stage; and a panel temperature determiner configured to measure sensing currents flowing through the pixels when a temperature sensing voltage is applied to the pixels, calculate sensing current averages of the pixel blocks, calculate correction sensing current averages by applying the global offset and the local offset to the sensing current averages, and determine temperatures of the pixel blocks by substituting the correction sensing current averages into the reference current-temperature model. 
     The display device may further include a temperature afterimage compensator configured to perform temperature afterimage compensation on image data that is to be applied to the pixel blocks based on the temperatures of the pixel blocks. 
     In the manufacturing stage, an average temperature of the display panel is measured by a temperature sensing device. 
     In the manufacturing stage, initial sensing currents flowing through the pixels when the temperature sensing voltage is applied to the pixels are measured, an average of the initial sensing currents is calculated, and a difference between a current mapped to the average temperature in the reference current-temperature model and the average of the initial sensing currents is determined as the global offset. 
     In the manufacturing stage, initial sensing currents flowing through the pixels when the temperature sensing voltage is applied to the pixels are measured, an average of the initial sensing currents is calculated, initial sensing current averages of the pixel blocks are calculated, and a difference between each of the initial sensing current averages of the pixel blocks and the average of the initial sensing currents is determined as the local offset. 
     A frame in which the display panel operates includes an active period and a vertical blank period, and the panel temperature determiner performs a sensing current measurement operation of measuring the sensing currents during the vertical blank period. 
     The panel temperature determiner performs the sensing current measurement operation for one pixel row during the vertical blank period. 
     The panel temperature determiner does not perform the sensing current measurement operation during the vertical blank period in a preset low gray level frame. 
     The panel temperature determiner determines the frame as the preset low gray level frame when a maximum gray level of image data of the frame is less than a reference gray level, determines the frame as the preset low gray level frame when a minimum gray level of the image data of the frame is less than the reference gray level, or determines the frame as the preset low gray level frame when an average gray level of the image data of the frame is less than the reference gray level. 
     The panel temperature determiner performs a panel temperature determination operation of determining the temperatures of the pixel blocks after the sensing current measurement operation for all of the pixels is completed. 
     According to example embodiments of the present disclosure, there is provided a display device including: a display panel including a plurality of pixels; a display panel driver configured to drive the display panel; a memory device configured to store a reference current-temperature model that is set for the display panel, a global offset of the display panel, which is calculated based on the reference current-temperature model, and a local offset of the display panel, which is calculated based on a characteristic difference between the pixels; and a panel temperature determiner configured to measure sensing currents flowing through the pixels when a temperature sensing voltage is applied to the pixels, calculate correction sensing currents by applying the global offset and the local offset to the sensing currents, and determine temperatures of the pixels by adjusting the reference current-temperature model with the correction sensing currents. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative, non-limiting example embodiments of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings. 
         FIG.  1    is a block diagram illustrating a display device according to example embodiments of the present disclosure. 
         FIG.  2    is a diagram illustrating a display panel included in the display device of  FIG.  1   . 
         FIG.  3    is a circuit diagram illustrating an example of a pixel included in the display device of  FIG.  1   . 
         FIG.  4    is a block diagram illustrating a panel temperature determiner included in the display device of  FIG.  1    determining a temperature of a pixel. 
         FIG.  5    is a diagram illustrating an example in which a sensing current measurement operation and a panel temperature determination operation for a pixel are performed in the display device of  FIG.  1   . 
         FIG.  6    is a flowchart illustrating a calculation of a global offset stored in a memory device included in the display device of  FIG.  1   . 
         FIG.  7    is a diagram for describing a calculation of a global offset stored in a memory device included in the display device of  FIG.  1   . 
         FIG.  8    is a flowchart illustrating a calculation of a local offset stored in a memory device included in the display device of  FIG.  1   . 
         FIGS.  9 A and  9 B  are diagrams for describing a calculation of a local offset stored in a memory device included in the display device of  FIG.  1   . 
         FIG.  10    is a flowchart illustrating a panel temperature determiner included in the display device of  FIG.  1    determining whether to perform a sensing current measurement operation based on image data of a frame. 
         FIG.  11    is a block diagram illustrating a display device according to example embodiments of the present disclosure. 
         FIG.  12    is a diagram illustrating a display panel included in the display device of FIG.  11 . 
         FIG.  13    is a block diagram illustrating a panel temperature determiner included in the display device of  FIG.  11    determining a temperature of a pixel. 
         FIG.  14    is a flowchart illustrating a calculation of a local offset stored in a memory device included in the display device of  FIG.  11   . 
         FIG.  15    is a diagram for describing a calculation of a local offset stored in a memory device included in the display device of  FIG.  11   . 
         FIG.  16    is a block diagram illustrating an electronic device according to example embodiments of the present disclosure. 
         FIG.  17    is a diagram illustrating an example in which the electronic device of  FIG.  16    is implemented as a smart phone. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, example embodiments of the present disclosure will be explained in detail with reference to the accompanying drawings. 
       FIG.  1    is a block diagram illustrating a display device according to example embodiments of the present disclosure,  FIG.  2    is a diagram illustrating a display panel included in the display device of  FIG.  1   ,  FIG.  3    is a circuit diagram illustrating an example of a pixel included in the display device of  FIG.  1   , and  FIG.  4    is a block diagram illustrating a panel temperature determiner included in the display device of  FIG.  1    determining a temperature of a pixel. 
     Referring to  FIGS.  1  to  4   , a display device  100  may include a display panel  110 , a display panel driver  120  (also referred to as a display panel driving circuit), a memory device  130 , and a panel temperature determiner  140  (also referred to as a panel temperature determining circuit). In addition, the display device  100  may further include a temperature afterimage compensator  150  (also referred to as a temperature afterimage compensating circuit). In an example embodiment, the display device  100  may be an organic light emitting display device. However, since the above configuration has been provided for illustrative purposes, a type of the display device  100  is not limited thereto. 
     The display panel  110  may include a plurality of pixels P. In this case, the pixels P may include a red display pixel, a green display pixel, and a blue display pixel. As shown in  FIG.  2   , the pixels P may be arranged in rows and columns within the display panel  110 . The display panel  110  may perform a display operation in a unit of a frame, and one frame in which the display panel  110  operates may include an active period and a vertical blank period. 
     The pixel P may have a structure in which a sensing current SC is output through a sensing line SL when a temperature sensing voltage TSV is applied through a data line DL. For example, as shown in  FIG.  3   , the pixel P may include a driving transistor DT, a switching transistor ST, a sensing transistor MT, a storage capacitor CST, and an organic light emitting diode OLED. The driving transistor DT may include a first terminal configured to receive a high power supply voltage ELVDD, a second terminal connected to a second node N 2 , and a gate terminal connected to a first node N 1 . The switching transistor ST may include a first terminal connected to the data line DL, a second terminal connected to the first node N 1 , and a gate terminal connected to a gate line GL. The sensing transistor MT may include a first terminal connected to the second node N 2 , a second terminal connected to the sensing line SL, and a gate terminal connected to a sensing control line ML. The storage capacitor CST may include a first terminal connected to the first node N 1 , and a second terminal connected to the second node N 2 . The organic light emitting diode OLED may include a first terminal (e.g., an anode) connected to the second node N 2 , and a second terminal (e.g., a cathode) connected to a low power supply voltage ELVSS. 
     When the display operation is performed by the display panel  110 , the sensing current SC of the pixel P may be measured in the vertical blank period of the one frame. For example, as shown in  FIG.  3   , the temperature sensing voltage TSV applied through the data line DL may flow through the switching transistor ST (e.g., when the switching transistor ST is turned on by a gate signal GS) to be applied to the first node N 1 , and the sensing current SC may flow through the driving transistor DT due to the temperature sensing voltage TSV stored in the storage capacitor CST, so that the sensing current SC may flow through the sensing transistor MT (e.g., when the sensing transistor MT is turned on by a sensing control signal MS) to be output through the sensing line SL. In this case, even when the same temperature sensing voltage TSV is applied, the sensing current SC may vary according to a temperature PTEMP of the pixel P. For example, when the same temperature sensing voltage TSV is applied, the sensing current SC may be increased as the temperature PTEMP of the pixel P becomes higher, and the sensing current SC may be decreased as the temperature PTEMP of the pixel P becomes lower. Therefore, the display device  100  may predict the temperature PTEMP of the pixel P by applying the same temperature sensing voltage TSV (e.g., a voltage of 5 V) to the pixel P, and measuring the sensing current SC flowing through the pixel P. 
     The display panel driver  120  may drive the display panel  110 . To accomplish this, the display panel driver  120  may include a gate driver, a data driver, a sensing driver, a timing controller, and the like. The display panel  110  may be connected to the gate driver through gate lines GL, connected to the data driver through data lines DL, and connected to the sensing driver through sensing control lines ML, and the timing controller may be connected to the gate driver, the data driver, and the sensing driver. 
     The gate driver may provide gate signals GS to the display panel  110  through the gate lines GL. In other words, the gate driver may provide the gate signals GS to the pixels P. 
     The data driver may provide data signals DS (or data voltages) to the display panel  110  through the data lines DL. In other words, the data driver may provide the data signals DS to the pixels P. When a sensing current measurement operation for the pixels P is performed, the data driver may provide the temperature sensing voltage TSV to the pixels P through the data lines DL. 
     The sensing driver may provide sensing control signals MS to the display panel  110  through the sensing control lines ML. In other words, the sensing driver may provide the sensing control signals MS to the pixels P. 
     The timing controller may generate a plurality of control signals and provide the generated control signals to the gate driver, the data driver, and the sensing driver to control the gate driver, the data driver, and the sensing driver. In some embodiments, the timing controller may perform a predetermined processing (e.g., a deterioration compensation) on image data CIMG on which temperature afterimage compensation is performed, or on image data IMG before performing the temperature afterimage compensation. 
     The memory device  130  may store a reference current-temperature model MOD that is set for the display panel  110 , a global offset GOFS of the display panel  110 , which is calculated based on the reference current-temperature model MOD in a manufacturing stage of the display panel  110  (e.g., denoted by FACTORY in  FIG.  4   ), and a local offset LOFS of the display panel  110 , which is calculated based on a characteristic difference between the pixels P in the manufacturing stage of the display panel  110 . The reference current-temperature model MOD is a representative model that is set for the display panel  110  by a manufacturer, and may include a relationship between the sensing current SC flowing through the pixel P and the temperature PTEMP of the pixel P when a preset temperature sensing voltage TSV (e.g., a voltage of 5 V) is applied to the pixel P included in the display panel  110 . Therefore, the reference current-temperature model MOD may be set by the manufacturer (e.g., through an experiment, etc.) in consideration of a size, a resolution, backplane characteristics, and the like of the display panel  110 , and may be collectively applied to the same products of the display panel  110 . The reference current-temperature model MOD may be a linear model having an inclination of a temperature with respect to a current. In some embodiments, the reference current-temperature model MOD may be a piecewise linear model in which the inclination of the temperature with respect to the current varies for each section. 
     In an ideal case, when the same temperature sensing voltage TSV is applied to the pixels P included in the same product, in other words, the same display panel  110  at the same temperature, all of the sensing currents SC flowing through the pixels P should be equal to each other. However, since a characteristic deviation exists between pixels P included in one display panel  110  due to various aspects of a manufacturing process, even when the same temperature sensing voltage TSV is applied to the pixels P included in the display panel  110  at the same temperature, the sensing currents SC flowing through the pixels P may not be equal to each other. In addition, since a characteristic deviation exists even between the same display panels  110  (e.g., the same products) due to various aspects of the manufacturing process, even when the same temperature sensing voltage TSV is applied to the same display panels  110  at the same temperature, the sensing currents SC flowing through the display panels  110  may not be equal to each other. 
     For this reason, the memory device  130  may store the representative model that is set for the display panel  110  by a manufacturer, in other words, the reference current-temperature model MOD, and may store the global offset GOFS and the local offset LOFS of the display panel  110  when the global offset GOFS for removing the characteristic deviation existing between the display panels  110  in the manufacturing stage of the display panel  110  and the local offset LOFS for removing the characteristic deviation between the pixels P within the display panel  110  are calculated (e.g., denoted by OFFSET CALCULATION in  FIG.  4   ). Accordingly, the display device  100  may predict the temperatures PTEMP of the pixels P (e.g., a panel temperature of the display panel  110 ) by measuring the sensing currents SC flowing through the pixels P as the temperature sensing voltage TSV is applied to the pixels P when the display panel  110  operates, applying the global offset GOFS and the local offset LOFS of the display panel  110  to the sensing currents SC, and substituting an application result into the reference current-temperature model MOD. In other words, the display device  100  may adjust (or update) the reference current-temperature model MOD with the result of applying the global offset GOFS and the local offset LOFS of the display panel  110  to the sensing currents SC. A method of calculating the global offset GOFS of the display panel  110  will be described below with reference to  FIGS.  6  and  7   , and a method of calculating the local offset LOFS of the display panel  110  will be described below with reference to  FIGS.  8  to  9 B . 
     The panel temperature determiner  140  may determine the temperatures PTEMP of the pixels P in an operation stage of the display panel  110  (e.g., denoted by REAL-TIME in  FIG.  4   ). For example, the panel temperature determiner  140  may measure the sensing currents SC flowing through the pixels P as the temperature sensing voltage TSV is applied to the pixels P, calculate correction sensing currents CSC by applying the global offset GOFS and the local offset LOFS of the display panel  110  to the sensing currents SC, and determine the temperatures PTEMP of the pixels P by substituting the correction sensing currents CSC into the representative model that is set for the display panel  110  by a manufacturer, in other words, the reference current-temperature model MOD. In other words, as shown in  FIG.  4   , the sensing current SC flowing through the pixel P as the temperature sensing voltage TSV is applied to the pixel P may be measured (e.g., denoted by SENSING), the characteristic deviation existing between the display panels  110  may be removed as the global offset GOFS of the display panel  110  including the pixel P is applied to the sensing current SC, and the characteristic deviation between the pixels P within the display panel  110  including the pixel P may be removed as the local offset LOFS of the display panel  110  including the pixel P is applied to the sensing current SC. In this case, the temperature PTEMP of the pixel P may be accurately derived when the correction sensing current CSC obtained by applying the global offset GOFS and the local offset LOFS of the display panel  110  to the sensing current SC is substituted into the reference current-temperature model MOD (e.g., denoted by a look-up table (LUT) in  FIG.  4   ). For example, the value of the sensing current SC in the reference current-temperature model MOD is adjusted (or changed) based on the correction sensing current CSC. 
     The temperature afterimage compensator  150  may perform the temperature afterimage compensation on the image data IMG that is to be applied to the pixels P based on the temperatures PTEMP of the pixels P. For example, the temperature afterimage compensator  150  may receive the image data IMG that is to be applied to the pixels P from an external component (e.g., a graphic processing unit (GPU), etc.), receive the temperatures PTEMP of the pixels P from the panel temperature determiner  140 , compensate the image data IMG based on the temperatures PTEMP of the pixels P to generate compensated image data CIMG, and provide the compensated image data CIMG to the display panel driver  120 . Thereafter, the data driver included in the display panel driver  120  may convert the compensated image data CIMG into the data signal DS (e.g., the data voltage) and provide the data signals DS obtained through the conversion to the pixels P. 
     As described above, the display device  100  may include the display panel  110  including pixels P, the display panel driver  120  configured to drive the display panel  110 , the memory device  130  configured to store the reference current-temperature model MOD that is set for the display panel  110 , the global offset GOFS of the display panel  110 , which is calculated based on the reference current-temperature model MOD in a manufacturing stage of the display panel  110 , and the local offset LOFS of the display panel  110 , which is calculated based on a characteristic difference between the pixels P in the manufacturing stage of the display panel  110 , and the panel temperature determiner  140  configured to measure sensing currents SC flowing through the pixels P as a temperature sensing voltage TSV is applied to the pixels P, calculate correction sensing currents CSC by applying the global offset GOFS and the local offset LOFS of the display panel  110  to the sensing currents SC, and determine temperatures PTEMP of the pixels P by substituting the correction sensing currents CSC into the reference current-temperature model MOD. Accordingly, the display device  100  may not include a temperature sensor such that it can be manufactured at a low cost and in a small size, and may reflect all of a characteristic deviation between a plurality of the display panels  110 , a characteristic deviation between pixels P within its display panel  110 , and an external environment temperature at which its display panel  110  operates such that it can accurately identify temperatures PTEMP of the pixels P. Therefore, temperature afterimage compensation may be accurately performed on image data IMG that is to be applied to the pixels P through the temperature afterimage compensator  150 . Although the display panel driver  120  has been shown in  FIG.  1    as having a configuration that is provided separately from the panel temperature determiner  140  and the temperature afterimage compensator  150 , in some embodiments, at least two of the display panel driver  120 , the panel temperature determiner  140 , and the temperature afterimage compensator  150  may be implemented as one configuration. 
       FIG.  5    is a diagram illustrating an example in which a sensing current measurement operation and a panel temperature determination operation for a pixel are performed in the display device of  FIG.  1   . 
     Referring to  FIG.  5   , one frame  1 F in which the display panel  110  operates may include an active period FA and a vertical blank period FV, the sensing currents SC flowing through the pixels P during the vertical blank period FV of the one frame  1 F may be measured (e.g., denoted by SMP), and the temperatures PTEMP of the pixels P included in the display panel  110  may be determined in a unit of n frames nF (where n is an integer that is greater than or equal to 2) (e.g., denoted by TDP). 
     For example, the panel temperature determiner  140  may measure the sensing currents SC flowing through the pixels P during the vertical blank period FV of the one frame  1 F. In this case, since the panel temperature determiner  140  measures the sensing currents SC flowing through the pixels P only during the vertical blank period FV of the one frame  1 F, there may be a limit to the number of pixels P whose sensing currents SC are measured during the vertical blank period FV of the one frame  1 F. Therefore, the panel temperature determiner  140  may measure the sensing currents SC flowing through the pixels P included in the display panel  110  over the n frames nF. 
     For example, the panel temperature determiner  140  may perform the sensing current measurement operation SMP on one pixel row during the vertical blank period FV of the one frame  1 F. In an example embodiment, the panel temperature determiner  140  may perform the sensing current measurement operation SMP only on red display pixels, perform the sensing current measurement operation SMP only on green display pixels, or perform the sensing current measurement operation SMP only on blue display pixels when performing the sensing current measurement operation SMP on the one pixel row. In another example embodiment, the panel temperature determiner  140  may perform the sensing current measurement operation SMP on all of the red display pixels, the green display pixels, and the blue display pixels when performing the sensing current measurement operation SMP on the one pixel row. 
     In some example embodiments, the panel temperature determiner  140  may not perform the sensing current measurement operation SMP during the vertical blank period FV of the one frame  1 F under a predetermined condition (e.g., a condition in which the sensing current measurement operation SMP may be visually recognized by a user when the sensing current measurement operation SMP is performed, etc.). For example, in a low gray level frame in which image data IMG of the one frame  1 F has a relatively low gray level, when the temperature sensing voltage TSV is applied to one pixel row during the vertical blank period FV of the frame  1 F, the pixel row may be visually recognized by the user. Therefore, the panel temperature determiner  140  may not perform the sensing current measurement operation SMP during the vertical blank period FV of the one frame  1 F in a low gray level frame. This will be described in detail below with reference to  FIG.  10   . 
     Thereafter, when the sensing current measurement operation SMP for all of the pixels P included in the display panel  110  is completed, the panel temperature determiner  140  may perform a panel temperature determination operation TDP for determining the temperatures PTEMP of all the pixels P included in the display panel  110 . In this case, since the panel temperature determiner  140  measures the sensing currents SC flowing through the pixels P included in the display panel  110  over the n frames nF, the temperatures PTEMP of the pixels P included in the display panel  110  may be determined in a unit of the n frames nF (e.g., denoted by TDP). 
       FIG.  6    is a flowchart illustrating a calculation of a global offset stored in a memory device included in the display device of  FIG.  1   , and  FIG.  7    is a diagram for describing a calculation of a global offset stored in a memory device included in the display device of  FIG.  1   . 
     Referring to  FIGS.  6  and  7   , a global offset calculation method of  FIG.  6    may include measuring an average temperature T of a display panel  110  (S 110 ), applying a temperature sensing voltage TSV to pixels P of the display panel  110  (S 120 ), measuring initial sensing currents flowing through the pixels P of the display panel  110  (S 130 ), calculating an average I of the initial sensing currents (S 140 ), determining a current IR mapped to the average temperature T of the display panel  110  in a reference current-temperature model MOD (S 150 ), and determining a difference between the current IR mapped to the average temperature T of the display panel  110  and the average  1  of the initial sensing currents as a global offset GOFS (S 160 ). Since the initial sensing current of the pixel P measured in a manufacturing stage of the display panel  110  and the sensing current SC of the pixel P measured during a display operation of the display panel  110  are values that are to be substituted into the reference current-temperature model MOD, the initial sensing current of the pixel P measured in the manufacturing stage of the display panel  110  and the sensing current SC of the pixel P measured during the display operation of the display panel  110  may be determined in a unit of a current (CURRENT) axis of the reference current-temperature model MOD, and the average temperature T of the display panel  110  and the temperature PTEMP of the pixel P may be determined in a unit of a temperature (TEMP) axis of the reference current-temperature model MOD. 
     For example, the global offset calculation method of  FIG.  6    may include measuring the average temperature T of the display panel  110  (S 110 ). In this case, in the global offset calculation method of  FIG.  6   , the average temperature T of the display panel  110  may be measured by using a temperature sensing device in the manufacturing stage of the display panel  110 . The average temperature T of the display panel  110  may be used for determining the global offset GOFS of the display panel  110 , and may be an actual temperature of an environment in which the display panel  110  is manufactured (e.g., a factory, etc.) because the average temperature T of the display panel  110  is measured while the display panel  110  does not operate. For example,  FIG.  7    shows that an average temperature T of a first display panel measured by the temperature sensing device is T 1  (e.g., a temperature of an environment in which the first display panel is manufactured is T 1 ) in a situation where a global offset GOFS of the first display panel is determined, and an average temperature T of a second display panel measured by the temperature sensing device is T 2  (e.g., a temperature of an environment in which the second display panel is manufactured is T 2 ) in a situation where a global offset GOFS of the second display panel is determined. 
     Thereafter, the global offset calculation method of  FIG.  6    may include applying the temperature sensing voltage TSV to the pixels P of the display panel  110  (S 120 ), and measuring the initial sensing currents flowing through the pixels P of the display panel  110  (S 130 ). Since a sensing current measurement operation SMP for measuring sensing currents SC flowing through the pixels P is performed during a vertical blank period FV of one frame  1 F during a display operation of the display panel  110 , a sensing current measurement operation SMP for all of the pixels P included in the display panel  110  may be completed over n frames nF. However, since a sensing current measurement operation for measuring the initial sensing currents flowing through the pixels P is performed without any specific time constraint in the manufacturing stage of the display panel  110 , the sensing current measurement operation for all of the pixels P included in the display panel  110  may be performed at once during a preset time. 
     Next, when the initial sensing currents flowing through all of the pixels P included in the display panel  110  are measured, the global offset calculation method of  FIG.  6    may include calculating the average I of the initial sensing currents (S 140 ). For example,  FIG.  7    shows that an average I of initial sensing currents flowing through all of the pixels P included in the first display panel is I 1  when the average temperature T of the first display panel is T 1  in the situation where the global offset GOFS of the first display panel is determined, and an average I of initial sensing currents flowing through all of the pixels P included in the second display panel is I 2  when the average temperature T of the second display panel is T 2  in the situation where the global offset GOFS of the second display panel is determined. In this case, since all of a representative display panel, the first display panel, and the second display panel are the same products, it may be assumed that all of inclinations of temperatures with respect to currents are the same. In other words, it may be assumed that the representative display panel has a characteristic of the reference current-temperature model MOD, it may be assumed that the first display panel has a characteristic of a first current-temperature model CAN 1 , and it may be assumed that the second display panel has a characteristic of a second current-temperature model CAN 2 . As shown in  FIG.  7   , the reference current-temperature model MOD is located between the first current-temperature model CAN 1  and the second current-temperature model CAN 2 . 
     Thereafter, the global offset calculation method of  FIG.  6    may include determining the current IR mapped to the average temperature T of the display panel  110  in the reference current-temperature model MOD (S 150 ). For example,  FIG.  7    shows that a current IR mapped to T 1  that is the average temperature T of the first display panel in the reference current-temperature model MOD is IR 1  in the situation where the global offset GOFS of the first display panel is determined, and a current IR mapped to T 2  that is the average temperature T of the second display panel in the reference current-temperature model MOD is IR 2  in the situation where the global offset GOFS of the second display panel is determined. In mapping the current IR to T 1 , which is the average temperature T of the first display panel, the I 1  level of the first current-temperature model CAN 1  is denoted as IR 1  in the reference current-temperature model MOD. Similarly, in mapping the current IR to T 2 , which is the average temperature T of the second display panel, the I 2  level of the second current-temperature model CAN 2  is denoted as IR 2  in the reference current-temperature model MOD. 
     Next, the global offset calculation method of  FIG.  6    may include determining the difference between the current IR mapped to the average temperature T of the display panel  110  and the average I of the initial sensing currents as the global offset GOFS (S 160 ). For example, as shown in  FIG.  7   , since the average I of the initial sensing currents flowing through all of the pixels P included in the first display panel at T 1  that is the average temperature T of the first display panel is I 1 , and the current IR mapped to T 1  that is the average temperature T of the first display panel in the reference current-temperature model MOD is IR 1 , GOFS 1 , which is a global offset GOFS of the first display panel, may be determined as IR 1 -I 1  (in other words, IR 1  minus I 1 ) that corresponds to a difference between IR 1 , which is the current IR mapped to T 1  that is the average temperature T of the first display panel in the reference current-temperature model MOD, and I 1 , which is the average I of the initial sensing currents flowing through all of the pixels P included in the first display panel. In addition, since the average I of the initial sensing currents flowing through all of the pixels P included in the second display panel at T 2  that is the average temperature T of the second display panel is I 2 , and the current IR mapped to T 2  that is the average temperature T of the second display panel in the reference current-temperature model MOD is IR 2 , GOFS 2 , which is a global offset GOFS of the second display panel, may be determined as IR 2 −I 2  (in other words, IR 2  minus I 2 ) that corresponds to a difference between IR 2 , which is the current IR mapped to T 2  that is the average temperature T of the second display panel in the reference current-temperature model MOD, and I 2 , which is the average I of the initial sensing currents flowing through all of the pixels P included in the second display panel. 
       FIG.  8    is a flowchart illustrating a calculation of a local offset stored in a memory device included in the display device of  FIG.  1   , and  FIGS.  9 A and  9 B  are diagrams for describing a calculation of a local offset stored in a memory device included in the display device of  FIG.  1   . 
     Referring to  FIGS.  8  to  9 B , a local offset calculation method of  FIG.  8    may include setting a display panel  110  to a reference condition (S 210 ), applying a temperature sensing voltage TSV to pixels P of the display panel  110  (S 220 ), measuring initial sensing currents flowing through the pixels P of the display panel  110  (S 230 ), calculating an average I of the initial sensing currents (S 240 ), and determining a difference between each of the initial sensing currents and the average I of the initial sensing currents as a local offset LOFS of the display panel  110  (S 250 ). 
     For example, the local offset calculation method of  FIG.  8    may include setting the display panel  110  to the reference condition (S 210 ). In other words, the local offset LOFS of the display panel  110  may be used to remove a characteristic deviation existing between the pixels P included in the display panel  110  due to various causes in a manufacturing process, so that the display panel  110  may be set to the reference condition to put the pixels P under the same condition. For example, in the local offset calculation method of  FIG.  8   , the display panel  110  may be set to the reference condition by applying a black display gray level to the display panel  110 . 
     Thereafter, the local offset calculation method of  FIG.  8    may include applying the temperature sensing voltage TSV to the pixels P of the display panel  110  (S 220 ), and measuring the initial sensing currents flowing through the pixels P of the display panel  110  (S 230 ). Since a sensing current measurement operation SMP for measuring sensing currents SC flowing through the pixels P is performed during a vertical blank period FV of one frame  1 F during a display operation of the display panel  110 , a sensing current measurement operation SMP for all of the pixels P included in the display panel  110  may be completed over n frames nF. However, since a sensing current measurement operation for measuring the initial sensing currents flowing through the pixels P is performed without any specific time constraint in a manufacturing stage of the display panel  110 , the sensing current measurement operation for all of the pixels P included in the display panel  110  may be performed at once during a preset time. 
     Next, when the initial sensing currents flowing through all of the pixels P included in the display panel  110  are measured, the local offset calculation method of  FIG.  8    may include calculating the average I of the initial sensing currents (S 240 ). For example,  FIG.  9 A  shows a situation where a local offset LOFS of a first display panel is determined. In  FIG.  9 A , an average I of initial sensing currents flowing through all of the pixels P included in the first display panel is shown as CAN 1 . In addition,  FIG.  9 B  shows a situation where a local offset LOFS of a second display panel is determined. In  FIG.  9 B , an average I of initial sensing currents flowing through all of the pixels P included in the second display panel is shown as CAN 2 . 
     Thereafter, the local offset calculation method of  FIG.  8    may include determining the difference between each of the initial sensing currents and the average I of the initial sensing currents as the local offset LOFS (S 250 ). For example, as shown in  FIG.  9 A , in determining a local offset LOFS of the first display panel, LOFS 1  corresponding to a difference between an initial sensing current flowing through a first pixel P 1  and the average I of the initial sensing currents (e.g., denoted by CAN 1 ) may be determined as a local offset LOFS for the first pixel P 1 , LOFS 2  corresponding to a difference between an initial sensing current flowing through a second pixel P 2  and the average I of the initial sensing currents (e.g., denoted by CAN 1 ) may be determined as a local offset LOFS for the second pixel P 2 , LOFS 3  corresponding to a difference between an initial sensing current flowing through a third pixel P 3  and the average I of the initial sensing currents (e.g., denoted by CAN 1 ) may be determined as a local offset LOFS for the third pixel P 3 , and LOFSk corresponding to a difference between an initial sensing current flowing through a k th  pixel Pk (where k is an integer that is greater than or equal to 2) and the average I of the initial sensing currents (e.g., denoted by CAN 1 ) may be determined as a local offset LOFS for the k th  pixel Pk. Similarly, as shown in  FIG.  9 B , in determining a local offset LOFS of the second display panel, LOFS 1  corresponding to a difference between an initial sensing current flowing through a first pixel P 1  and the average I of the initial sensing currents (e.g., denoted by CAN 2 ) may be determined as a local offset LOFS for the first pixel P 1 , LOFS 2  corresponding to a difference between an initial sensing current flowing through a second pixel P 2  and the average I of the initial sensing currents (e.g., denoted by CAN 2 ) may be determined as a local offset LOFS for the second pixel P 2 , LOFS 3  corresponding to a difference between an initial sensing current flowing through a third pixel P 3  and the average I of the initial sensing currents (e.g., denoted by CAN 2 ) may be determined as a local offset LOFS for the third pixel P 3 , and LOFSk corresponding to a difference between an initial sensing current flowing through a k th  pixel Pk and the average I of the initial sensing currents (e.g., denoted by CAN 2 ) may be determined as a local offset LOFS for the k th  pixel Pk. 
       FIG.  10    is a flowchart illustrating a panel temperature determiner included in the display device of  FIG.  1    determining whether to perform a sensing current measurement operation based on image data of a frame. 
     Referring to  FIG.  10   , the panel temperature determiner  140  may analyze image data IMG of one frame  1 F (S 310 ), determine whether the one frame  1 F is a preset low gray level frame (S 320 ), not perform a sensing current measurement operation SMP on one pixel row during a vertical blank period FV of the one frame  1 F when the one frame  1 F is the preset low gray level frame (S 330 ), and perform the sensing current measurement operation SMP on the one pixel row during the vertical blank period FV of the one frame  1 F when the one frame  1 F is not the preset low gray level frame (S 340 ). In other words, the panel temperature determiner  140  may not perform the sensing current measurement operation SMP during the vertical blank period FV of the one frame  1 F in the preset low gray level frame. 
     As described above, the panel temperature determiner  140  may not perform the sensing current measurement operation SMP during the vertical blank period FV of the one frame  1 F under a predetermined condition (e.g., a condition in which the sensing current measurement operation SMP may be visually recognized by a user when the sensing current measurement operation SMP is performed, etc.). In other words, in a low gray level frame in which image data IMG of the one frame  1 F has a relatively low gray level, when a temperature sensing voltage TSV is applied to one pixel row during the vertical blank period FV of the frame  1 F, the pixel row may be visually recognized by a user. Therefore, the panel temperature determiner  140  may not perform the sensing current measurement operation SMP during the vertical blank period FV of the one frame  1 F in a preset low gray level frame. 
     In an example embodiment, the panel temperature determiner  140  may determine the one frame  1 F as the preset low gray level frame when a maximum gray level of the image data IMG of the one frame  1 F is less than a reference gray level. In another example embodiment, the panel temperature determiner  140  may determine the one frame  1 F as the preset low gray level frame when a minimum gray level of the image data IMG of the one frame  1 F is less than the reference gray level. In a still another example embodiment, the panel temperature determiner  140  may determine the one frame  1 F as the preset low gray level frame when an average gray level of the image data IMG of the one frame  1 F is less than the reference gray level. Although the determining of whether the one frame  1 F is the preset low gray level frame has been described above as being performed based on the image data IMG of the one frame  1 F, in some example embodiments, the determining of whether the one frame  1 F is the preset low gray level frame may be performed based on compensated image data CIMG of the one frame  1 F. 
       FIG.  11    is a block diagram illustrating a display device according to example embodiments of the present disclosure,  FIG.  12    is a diagram illustrating a display panel included in the display device of  FIG.  11   , and  FIG.  13    is a block diagram illustrating a panel temperature determiner included in the display device of  FIG.  11    determining a temperature of a pixel. 
     Referring to  FIGS.  11  to  13   , a display device  500  may include a display panel  510 , a display panel driver  520  (also referred to as a display panel driving circuit), a memory device  530 , and a panel temperature determiner  540  (also referred to as a panel temperature determining circuit). In addition, the display device  500  may further include a temperature afterimage compensator  550  (also referred to as a temperature afterimage compensating circuit). In an example embodiment, the display device  500  may be an organic light emitting display device. However, since the above configuration has been provided for illustrative purposes, a type of the display device  500  is not limited thereto. The display device  500  of  FIG.  11    is substantially the same as the display device  100  of  FIG.  1    except that the panel temperature determination operation is performed in a unit of pixel blocks PBL rather than the pixels P in terms of memory efficiency, and thus, redundant descriptions of the display device  500  of  FIG.  11    corresponding to the display device  100  of  FIG.  1    may be omitted. 
     The display panel  510  may include a plurality of pixels P, which are grouped into pixel blocks PBL. In this case, the pixels P may include a red display pixel, a green display pixel, and a blue display pixel. The pixel P may have a structure in which a sensing current SC is output through a sensing line when a temperature sensing voltage TSV is applied through a data line. As shown in  FIG.  12   , pixels P may be arranged in rows and columns within the display panel  510 , and adjacent pixels P may constitute one pixel block PBL. The number of pixels P constituting the pixel block PBL is not limited to that shown in  FIG.  12   . The display panel  510  may perform a display operation in a unit of a frame, and one frame in which the display panel  510  operates may include an active period and a vertical blank period. When the display operation is performed by the display panel  510 , the sensing current SC of the pixel P may be measured in the vertical blank period of the one frame. 
     The display panel driver  520  may drive the display panel  510 . To accomplish this, the display panel driver  520  may include a gate driver, a data driver, a sensing driver, a timing controller, and the like. The gate driver may provide gate signals GS to the display panel  510  through the gate lines GL. The data driver may provide data signal DS (or data voltages) to the display panel  510  through the data lines DL. When a sensing current measurement operation for the pixels P is performed, the data driver may provide the temperature sensing voltage TSV to the pixels P through the data lines DL. The sensing driver may provide sensing control signals MS to the display panel  510  through the sensing control lines ML. The timing controller may generate a plurality of control signals and provide the generated control signals to the gate driver, the data driver, and the sensing driver to control the gate driver, the data driver, and the sensing driver. In some example embodiments, the timing controller may perform a predetermined processing (e.g., deterioration compensation) on image data CIMG on which temperature afterimage compensation is performed, or on image data IMG which has not undergone the temperature afterimage compensation. 
     The memory device  530  may store a reference current-temperature model MOD that is set for the display panel  510 , a global offset GOFS of the display panel  510 , which is calculated based on the reference current-temperature model MOD in a manufacturing stage of the display panel  510  (e.g., denoted by FACTORY in  FIG.  13   ), and a local offset LOFS of the display panel  510 , which is calculated based on a characteristic difference between the pixel blocks PBL in the manufacturing stage of the display panel  510 . The reference current-temperature model MOD may be a linear model having an inclination of a temperature with respect to a current. In some example embodiments, the reference current-temperature model MOD may be a piecewise linear model in which the inclination of the temperature with respect to the current varies for each section. 
     In an ideal case, when the same temperature sensing voltage TSV is applied to the pixels P included in the same product, in other words, the same display panel  510  at the same temperature, all of the sensing currents SC flowing through the pixels P should be equal to each other. However, since a characteristic deviation exists between the pixels P included in one display panel  510  due to various aspects of a manufacturing process, even when the same temperature sensing voltage TSV is applied to the pixels P included in the display panel  510  at the same temperature, the sensing currents SC flowing through the pixels P may not be equal to each other. In other words, even when the same temperature sensing voltage TSV is applied to the pixel blocks PBL included in the display panel  510  at the same temperature, sensing current averages ASC flowing through the pixel blocks PBL may not be equal to each other. In addition, since a characteristic deviation exists even between the same display panels  510  (e.g., the same products) due to various aspects of the manufacturing process, even when the same temperature sensing voltage TSV is applied to the same display panels  510  at the same temperature, the sensing currents SC flowing through the display panels  510  may not be equal to each other. 
     For this reason, the memory device  530  may store a representative model that is set for the display panel  510  by a manufacturer, in other words, the reference current-temperature model MOD, and may store the global offset GOFS and the local offset LOFS of the display panel  510  when the global offset GOFS for removing the characteristic deviation existing between the display panels  510  in the manufacturing stage of the display panel  510  and the local offset LOFS for removing the characteristic deviation between the pixel blocks PBL within the display panel  510  are calculated (e.g., denoted by OFFSET CALCULATION in  FIG.  13   ). Accordingly, the display device  500  may predict temperatures BTEMP of the pixel blocks PBL (e.g., a panel temperature of the display panel  510 ) by measuring the sensing currents SC flowing through the pixels P as the temperature sensing voltage TSV is applied to the pixels P when the display panel  510  operates, calculating averages of the sensing currents SC for each pixel block (e.g., denoted by SC 1  to SCm) to calculate the sensing current averages ASC of the pixel blocks PBL, applying the global offset GOFS and the local offset LOFS of the display panel  510  to the sensing current averages ASC to calculate correction sensing current averages CASC of the pixel blocks PBL, and substituting the correction sensing current averages CASC into the reference current-temperature model MOD. A method of calculating the global offset GOFS of the display panel  510  may be substantially the same as the method of calculating the global offset GOFS described with reference to  FIGS.  6  and  7   , and a method of calculating the local offset LOFS of the display panel  510  will be described below with reference to  FIGS.  14  and  15   . 
     The panel temperature determiner  540  may determine the temperatures BTEMP of the pixel blocks PBL in an operation stage of the display panel  510  (e.g., denoted by REAL-TIME in  FIG.  13   ). For example, the panel temperature determiner  540  may measure the sensing currents SC flowing through the pixels P as the temperature sensing voltage TSV is applied to the pixels P, calculate the sensing current averages ASC of the pixel blocks PBL, each of which includes a plurality of pixels P, calculate the correction sensing current averages CASC by applying the global offset GOFS and the local offset LOFS of the display panel  510  to the sensing current averages ASC, and determine the temperatures BTEMP of the pixel blocks PBL by substituting the correction sensing current averages CASC into the representative model that is set for the display panel  510  by the manufacturer, in other words, the reference current-temperature model MOD. In other words, as shown in  FIG.  13   , the sensing currents SC 1  to SCm flowing through the pixels P included in the pixel block PBL as the temperature sensing voltage TSV is applied to the pixel block PBL may be measured, the average of the sensing currents SC 1  to SCm, in other words, the sensing current averages ASC may be calculated (e.g., denoted by AVERAGE in  FIG.  13   ), the characteristic deviation existing between the display panels  510  may be removed as the global offset GOFS of the display panel  510  including the pixel block PBL is applied to the sensing current average ASC, and the characteristic deviation between the pixel blocks PBL within the display panel  510  including the pixel block PBL may be removed as the local offset LOFS of the display panel  510  including the pixel block PBL is applied to the sensing current average ASC. In this case, the temperature BTEMP of the pixel block PBL may be accurately derived when the correction sensing current average CASC obtained by applying the global offset GOFS and the local offset LOFS of the display panel  510  to the sensing current average ASC of the pixel block PBL is substituted into the reference current-temperature model MOD (e.g., denoted by LUT in  FIG.  13   ). 
     The temperature afterimage compensator  550  may perform the temperature afterimage compensation on image data IMG that is to be applied to the pixel blocks PBL based on the temperatures BTEMP of the pixel blocks PBL. For example, the temperature afterimage compensator  550  may receive the image data IMG that is to be applied to the pixel blocks PBL (specifically, the image data IMG that is to be applied to the pixels P included in each of the pixel blocks PBL) from an external component (e.g., a graphic processing unit, etc.), receive the temperatures BTEMP of the pixel blocks PBL from the panel temperature determiner  540 , compensate the image data IMG based on the temperatures BTEMP of the pixel blocks PBL to generate compensated image data CIMG, and provide the compensated image data CIMG to the display panel driver  520 . Thereafter, the data driver included in the display panel driver  520  may convert the compensated image data CIMG into the data signal DS (e.g., the data voltage) and provide the data signals DS obtained through the conversion to the pixel blocks PBL (specifically, provide the data signal DS to the pixels P included in each of the pixel blocks PBL). 
     As described above, the display device  500  may include the display panel  510  including pixels P grouped into pixel blocks PBL, the display panel driver  520  configured to drive the display panel  510 , the memory device  530  configured to store the reference current-temperature model MOD that is set for the display panel  510 , the global offset GOFS of the display panel  510 , which is calculated based on the reference current-temperature model MOD in a manufacturing stage of the display panel  510 , and the local offset LOFS of the display panel  510 , which is calculated based on a characteristic difference between the pixel blocks PBL in the manufacturing stage of the display panel  510 , and the panel temperature determiner  540  configured to measure sensing currents SC flowing through the pixels P as a temperature sensing voltage TSV is applied to the pixels P, calculate sensing current averages ASC of the pixel blocks PBL, calculate correction sensing current averages CASC by applying the global offset GOFS and the local offset LOFS of the display panel  510  to the sensing current averages ASC of the pixel blocks PBL, and determine temperatures BTEMP of the pixel blocks PBL by substituting the correction sensing current averages CASC into the reference current-temperature model MOD. Accordingly, the display device  500  may not contain a temperature sensor so such that it can be manufactured in a low cost and in a small size, and may reflect all of a characteristic deviation between display panels  510 , a characteristic deviation between pixels P within the display panel  510 , and an external environment temperature at which the display panel  510  operates such that it can accurately identify the temperature BTEMP of the pixel blocks PBL. Therefore, temperature afterimage compensation may be accurately performed on image data IMG that is to be applied to the pixel blocks PBL through the temperature afterimage compensator  550 . Although the display panel driver  520  has been shown in  FIG.  11    as having a configuration that is provided separately from the panel temperature determiner  540  and the temperature afterimage compensator  550 , in some example embodiments, at least two of the display panel driver  520 , the panel temperature determiner  540 , and the temperature afterimage compensator  550  may be implemented as one configuration. 
       FIG.  14    is a flowchart illustrating a calculation of a local offset stored in a memory device included in the display device of  FIG.  11   , and  FIG.  15    is a diagram for describing a calculation of a local offset stored in a memory device included in the display device of  FIG.  11   . 
     Referring to  FIGS.  14  and  15   , a local offset calculation method of  FIG.  14    may include setting a display panel  510  to a reference condition (S 410 ), applying a temperature sensing voltage TSV to pixels P of the display panel  510  (S 420 ), measuring initial sensing currents flowing through the pixels P of the display panel  510  (S 430 ), calculating an average I of the initial sensing currents (S 440 ), calculating initial sensing current averages ASC of pixel blocks PBL (S 450 ), and determining a difference between each of the initial sensing current averages ASC of the pixel blocks PBL and the average I of the initial sensing currents as a local offset LOFS of the display panel  510  (S 460 ). 
     For example, the local offset calculation method of  FIG.  14    may include setting the display panel  510  to the reference condition (S 410 ). In other words, the local offset LOFS of the display panel  510  may be used to remove a characteristic deviation existing between the pixel blocks PBL included in one display panel  510  due to various causes in a manufacturing process, so that the display panel  510  may be set to the reference condition to put the pixel blocks PBL under the same condition. For example, in the local offset calculation method of  FIG.  14   , the display panel  510  may be set to the reference condition by applying a black display gray level to the display panel  510 . 
     Thereafter, the local offset calculation method of  FIG.  14    may include applying the temperature sensing voltage TSV to the pixels P of the display panel  510  (S 420 ), and measuring the initial sensing currents flowing through the pixels P of the display panel  510  (S 430 ). Since a sensing current measurement operation for measuring sensing currents SC flowing through the pixels P is performed during a vertical blank period of one frame during a display operation of the display panel  510 , a sensing current measurement operation for all of the pixels P included in the display panel  510  may be completed over n frames. However, since a sensing current measurement operation for measuring the initial sensing currents flowing through the pixels P is performed without any specific time constraint in a manufacturing stage of the display panel  510 , the sensing current measurement operation for all the pixels P included in the display panel  510  may be performed at once during a preset time. 
     Next, when the initial sensing currents flowing through all of the pixels P included in the display panel  510  are measured, the local offset calculation method of  FIG.  14    may include calculating the average I of the initial sensing currents (S 440 ). For example,  FIG.  15    shows a situation where the local offset LOFS of the display panel  510  is determined. In  FIG.  15   , the average I of the initial sensing currents flowing through all of the pixels P included in the display panel  510  has been shown as CAN. 
     Thereafter, the local offset calculation method of  FIG.  14    may include calculating the initial sensing current averages ASC of the pixel blocks PBL (S 450 ). For example, when assuming that one pixel block PBL includes m pixels P, the initial sensing current average ASC of the pixel block PBL may be an average of m initial sensing currents flowing through the m pixels P included in the pixel block PBL. 
     Next, the local offset calculation method of  FIG.  14    may include determining the difference between each of the initial sensing current averages ASC of the pixel blocks PBL and the average I of the initial sensing currents as the local offset LOFS of the display panel  510  (S 460 ). For example, as shown in  FIG.  15   , in determining the local offset LOFS of the display panel  510 , LOFS 1  corresponding to a difference between an initial sensing current average ASC of a first pixel block PBL 1  and the average I of the initial sensing currents (e.g., denoted by CAN) may be determined as a local offset LOFS for the first pixel block PBL 1 , LOFS 2  corresponding to a difference between an initial sensing current average ASC of a second pixel block PBL 2  and the average I of the initial sensing currents (e.g., denoted by CAN) may be determined as a local offset LOFS for the second pixel block PBL 2 , LOFS 3  corresponding to a difference between an initial sensing current average ASC of a third pixel block PBL 3  and the average I of the initial sensing currents (e.g., denoted by CAN) may be determined as a local offset LOFS for the third pixel block PBL 3 , and LOFSk corresponding to a difference between an initial sensing current average ASC of a k th  pixel block PBLk and the average I of the initial sensing currents (e.g., denoted by CAN) may be determined as a local offset LOFS for the k th  pixel block PBLk. 
       FIG.  16    is a block diagram illustrating an electronic device according to example embodiments of the present disclosure, and  FIG.  17    is a diagram illustrating an example in which the electronic device of  FIG.  16    is implemented as a smart phone. 
     Referring to  FIGS.  16  and  17   , the electronic device  1000  may include a processor  1010 , a memory device  1020 , a storage device  1030 , an input/output (I/O) device  1040 , a power supply  1050 , and a display device  1060 . Here, the display device  1060  may be the display device  100  of  FIG.  1    or the display device  500  of  FIG.  11   . In addition, the electronic device  1000  may further include a plurality of ports for communicating with a video card, a sound card, a memory card, a universal serial bus (USB) device, other electronic devices, etc. In an example embodiment, as illustrated in  FIG.  17   , the electronic device  1000  may be implemented as a smart phone. However, the electronic device  1000  is not limited thereto. For example, the electronic device  1000  may be implemented as a cellular phone, a video phone, a smart pad, a smart watch, a tablet PC, a car navigation system, a computer monitor, a laptop, a head mounted display (HMD) device, etc. 
     The processor  1010  may perform various computing functions. The processor  1010  may be a micro processor, a central processing unit (CPU), an application processor (AP), etc. The processor  1010  may be coupled to other components via an address bus, a control bus, a data bus, etc. Further, the processor  1010  may be coupled to an extended bus such as a peripheral component interconnection (PCI) bus. 
     The memory device  1020  may store data for operations of the electronic device  1000 . For example, the memory device  1020  may include at least one non-volatile memory device such as an erasable programmable read-only memory (EPROM) device, an electrically erasable programmable read-only memory (EEPROM) device, a flash memory device, a phase change random access memory (PRAM) device, a resistance random access memory (RRAM) device, a nano floating gate memory (NFGM) device, a polymer random access memory (PoRAM) device, a magnetic random access memory (MRAM) device, a ferroelectric random access memory (FRAM) device, etc and/or at least one volatile memory device such as a dynamic random access memory (DRAM) device, a static random access memory (SRAM) device, a mobile DRAM device, etc. 
     The storage device  1030  may include a solid state drive (SSD) device, a hard disk drive (HDD) device, a compact disc-read only memory (CD-ROM) device, etc. 
     The I/O device  1040  may include an input device such as a keyboard, a keypad, a mouse device, a touch-pad, a touch-screen, etc, and an output device such as a printer, a speaker, etc. In some example embodiments, the I/O device  1040  may include the display device  1060 . 
     The power supply  1050  may provide power for operations of the electronic device  1000 . For example, the power supply  1050  may be a power management integrated circuit (PMIC). 
     The display device  1060  may display an image corresponding to visual information of the electronic device  1000 . In an example embodiment, the display device  1060  may be an organic light emitting display device. The display device  1060  may be connected to other components through buses or other communication links. In this case, the display device  1060  may not include a temperature sensor so that it can be manufactured at a low cost and in a small size, and may reflect all of a characteristic deviation between display devices  1060  (e.g., the same products), a characteristic deviation between pixels within the display device  1060 , and an external environment at which the display device  1060  operates so that it can accurately identify temperatures of the pixels (or temperatures of pixel blocks). Therefore, temperature afterimage compensation may be accurately performed on image data that is to be applied to the pixels (or the pixel blocks). 
     In an example embodiment, the display device  1060  may include a display panel including pixels, a display panel driver configured to drive the display panel, a memory device configured to store a reference current-temperature model that is set for the display panel, a global offset of the display panel, which is calculated based on the reference current-temperature model in a manufacturing stage of the display panel, and a local offset of the display panel, which is calculated based on a characteristic difference between the pixels in the manufacturing stage of the display panel, and a panel temperature determiner configured to measure sensing currents flowing through the pixels as a temperature sensing voltage is applied to the pixels, calculate correction sensing currents by applying the global offset and the local offset of the display panel to the sensing currents, and determine temperatures of the pixels by substituting the correction sensing currents into the reference current-temperature model. Since theses are described above with reference to  FIGS.  1  to  10   , duplicated description related thereto will not be repeated. 
     In another example embodiment, the display device  1060  may include a display panel including pixels grouped into pixel blocks, a display panel driver configured to drive the display panel, a memory device configured to store a reference current-temperature model that is set for the display panel, a global offset of the display panel, which is calculated based on the reference current-temperature model in a manufacturing stage of the display panel, and a local offset of the display panel, which is calculated based on a characteristic difference between the pixel blocks in the manufacturing stage of the display panel, and a panel temperature determiner configured to measure sensing currents flowing through the pixels as a temperature sensing voltage is applied to the pixels, calculate sensing current averages of the pixel blocks, calculate correction sensing current averages by applying the global offset and the local offset of the display panel to the sensing current averages of the pixel blocks, and determine temperatures of the pixel blocks by substituting the correction sensing current averages into the reference current-temperature model. Since theses are described above with reference to  FIGS.  11  to  15   , duplicated description related thereto will not be repeated. 
     The present disclosure may be applied to a display device and an electronic device including the display device. For example, the present disclosure may be applied to a smart phone, a cellular phone, a video phone, a smart pad, a smart watch, a tablet PC, a car navigation system, a television, a computer monitor, a laptop, a head mounted display device, an MP 3  player, etc. 
     The foregoing is illustrative of example embodiments of the present disclosure and is not to be construed as limiting thereof. Although a few example embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in the example embodiments without departing from the scope of the present disclosure. Accordingly, all such modifications are intended to be included within the scope of the present disclosure as set forth in the claims.