Patent Publication Number: US-10777108-B2

Title: Display device and method of driving the same

Description:
This application claims priority to Korean Patent Application No. 10-2017-0153373, filed on Nov. 16, 2017, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which in its entirety is herein incorporated by reference. 
     BACKGROUND 
     1. Field of Disclosure 
     The invention relates to a display device having a temperature compensation function and a method of driving the display device. 
     2. Description of the Related Art 
     A display device generally includes a display panel displaying an image and a driving circuit driving the display panel. The display panel includes gate lines, data lines, and pixels. The driving circuit generates various driving voltages required for an operation the display panel. 
     Operating characteristics of the driving circuit varies due to a difference in charge mobility depending on a temperature. 
     SUMMARY 
     Particularly, when the charge mobility decreases in a low-temperature environment, the pixels are not sufficiently turned on. 
     The invention provides a display device capable of compensating for lowered mobility of charges of gate drivers at a low temperature depending on a positional relationship with a light source unit. 
     The invention provides a method of driving the display device. 
     Exemplary embodiments of the inventive concept provide a display device including a display panel which includes a plurality of gate lines extending in a first direction and a plurality of data lines extending in a second direction crossing the first direction, a gate driver electrically connected to the gate lines, a temperature sensor which includes at least three temperature sensing circuits which are disposed adjacent to the gate driver, and a voltage generating circuit which outputs a test voltage to each of the temperature sensing circuits and outputs a clock signal, which is compensated based on a result voltage having a lowest voltage level among result voltages provided from the temperature sensing circuits, to the gate driver. 
     In an exemplary embodiment, each of the temperature sensing circuits may include a plurality of diode-connected transistors connected to each other in series. 
     In an exemplary embodiment, the gate driver may include a first gate driver and a second gate driver, the first gate driver and the second gate driver may be disposed spaced apart from each other such that the gate lines are disposed between the first gate driver and the second gate driver, and the temperature sensing circuits may be disposed adjacent to the first gate driver or the second gate driver in the first direction. 
     In an exemplary embodiment, the display panel may include a first area, a second area, and a third area, which are sequentially defined in the second direction, and the temperature sensor may include a first temperature sensing circuit disposed in the first area, a second temperature sensing circuit disposed in the second area, and a third temperature sensing circuit disposed in the third area. 
     In an exemplary embodiment, at least one temperature sensing circuit among the first, second, and third temperature sensing circuits may be disposed adjacent to the first gate driver, and at least one remaining temperature sensing circuit among the first, second, and third temperature sensing circuits may be disposed adjacent to the second gate driver. 
     In an exemplary embodiment, the temperature sensor may further include a fourth temperature sensing circuit disposed in the first area, a fifth temperature sensing circuit disposed in the second area, and a sixth temperature sensing circuit disposed in the third area, the first, second, and third temperature sensing circuits may be disposed adjacent to the first gate driver, and the fourth, fifth, and sixth temperature sensing circuits may be disposed adjacent to the second gate driver. 
     In an exemplary embodiment, a number of first diode-connected transistors included in the first temperature sensing circuit, a number of second diode-connected transistors included in the second temperature sensing circuit, and a number of third diode-connected transistors included in the third temperature sensing circuit may be equal to each other. 
     In an exemplary embodiment, a sum of the number of first diode-connected transistors, the number of second diode-connected transistors, and the number of third diode-connected transistors may be equal to a number of the gate lines. 
     In an exemplary embodiment, the first temperature sensing circuit may include a first switch, the second temperature sensing circuit may include a second switch, the third temperature sensing circuit may include a third switch, and the first, second, and third switches may be sequentially turned on, receive the test voltage from the voltage generating circuit, and output the result voltage changed depending on a temperature of the first gate driver or the second gate driver adjacent thereto to the voltage generating circuit. 
     In an exemplary embodiment, the voltage generating circuit may include a switch signal generator which generates a signal to sequentially turn on the first switch, the second switch, and the third switch, a voltage output and sensing unit which outputs the test voltage and receiving the result voltages, a compensation reference determination unit which compares voltage drops from the test voltage to the result voltages to determine a compensation reference, and a compensator which compensates for the clock signal based on the compensation reference. 
     In an exemplary embodiment, the diode-connected transistors included in each of the temperature sensing circuits may be arranged along the second direction. 
     Exemplary embodiments of the inventive concept provide a display device including a display panel which includes a plurality of gate lines extending in a first direction and a plurality of data lines extending in a second direction crossing the first direction and includes a first area, a second area, and a third area, which are sequentially defined along the second direction, a gate driver which outputs a gate signal to the gate lines and disposed in the first, second, and third areas, a temperature sensor which includes a first temperature sensing circuit disposed in the first area, a second temperature sensing circuit disposed in the second area, and a third temperature sensing circuit disposed in the third area which are adjacent to the gate driver, and a voltage generating circuit which outputs a test voltage to each of the first, second, and third temperature sensing circuits and outputs a clock signal, which is compensated based on first, second, and third result voltages provided from the first, second, and third temperature sensing circuits respectively, to the gate driver. 
     In an exemplary embodiment, the voltage generating circuit may compare the test voltage with each of the first, second, and third result voltages and compensate for the clock signal based on a voltage having a largest voltage drop among voltage drops from the test voltage to the first, second, and third result voltages. 
     In an exemplary embodiment, the gate driver may include a first gate driver and a second gate driver, the first gate driver and the second gate driver may be disposed to be spaced apart from each other such that the gate lines are disposed between the first gate driver and the second gate driver, and the first, second, and third temperature sensing circuits may be disposed adjacent to the first gate driver or the second gate driver in the first direction. 
     In an exemplary embodiment, at least one temperature sensing circuit among the first, second, and third temperature sensing circuits may be disposed adjacent to the first gate driver, and at least one remaining temperature sensing circuit among the first, second, and third temperature sensing circuits may be disposed adjacent to the second gate driver. 
     In an exemplary embodiment, the temperature sensor may further include a fourth temperature sensing circuit disposed in the first area, a fifth temperature sensing circuit disposed in the second area, and a sixth temperature sensing circuit disposed in the third area, the first, second, and third temperature sensing circuits may be disposed adjacent to the first gate driver, and the fourth, fifth, and sixth temperature sensing circuits may be disposed adjacent to the second gate driver. 
     In an exemplary embodiment, each of the first, second, and third temperature sensing circuits may include a plurality of diode-connected transistors connected to each other in series. 
     Exemplary embodiments of the inventive concept provide a method of driving a display device, which includes a display panel including a gate driver and first, second, and third temperature sensing circuits integrated in an area adjacent to the gate driver, including sequentially providing a test voltage to the first, second, and third temperature sensing circuits, sequentially receiving first, second, and third result voltages, which are voltage-dropped from the test voltage, from the first, second, and third temperature sensing circuits respectively, comparing the test voltage with each of the first, second, and third result voltages, and controlling a voltage level of a clock signal applied to the gate driver based on a result voltage having a largest voltage drop among the first, second, and third result voltages. 
     In an exemplary embodiment, the test voltage may be provided after a predetermined time elapses from a time point at which the display device is turned on. 
     In an exemplary embodiment, the method may further include generating a switch signal to provide the test voltage to one of the first, second, and third temperature sensing circuits. 
     According to the above, although a positional relationship between the display panel and the light source unit is changed, the voltage level of gate-on and -off voltage is compensated based on the result voltage having the largest voltage drop among the result voltages sensed by the temperature sensing circuits. That is, the voltage level of gate-on and -off voltage may be compensated for the lowered mobility of the charges of the thin film transistors at the lowest temperature. Accordingly, the phenomenon in which the pixel is not sufficiently turned on may be effectively prevented from occurring. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other advantages of the invention will become readily apparent by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein: 
         FIG. 1  is a block diagram showing an exemplary embodiment of a display device according to the invention; 
         FIG. 2  is a plan view showing an exemplary embodiment of some elements of a display device according to the invention; 
         FIG. 3  is a plan view showing an exemplary embodiment of a display panel according to the invention; 
         FIG. 4  is a block diagram showing an exemplary embodiment of a voltage generating circuit and an equivalent circuit diagram showing a temperature sensor according to the invention; 
         FIG. 5A  is a view showing a test voltage and a result voltage according to an exemplary embodiment of the invention; 
         FIG. 5B  is a view showing a test voltage and a result voltage according to another exemplary embodiment of the invention; 
         FIG. 6  is a flowchart showing an exemplary embodiment of a compensation operation of a gate driver according to the invention; 
         FIG. 7  is a plan view showing another exemplary embodiment of a display panel according to the invention; and 
         FIG. 8  is a plan view showing still another exemplary embodiment of a display panel according to the invention. 
     
    
    
     DETAILED DESCRIPTION 
     The invention may be variously modified and realized in many different forms, and thus specific embodiments will be exemplified in the drawings and described in detail hereinbelow. However, the invention should trot be limited to the specific disclosed forms, and be construed to include all modifications, equivalents, or replacements included in the spirit and scope of the invention. 
     It will be further understood that the terms “includes” and/or “including”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     The use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of the invention. It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. “At least one” is not to be construed as limiting “a” or “an.” “Or” means “and/or.” 
     In the drawings, proportions and dimensions of components are exaggerated for clarity. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
     Hereinafter, the invention will be explained in detail with reference to the accompanying drawings. 
       FIG. 1  is a block diagram showing an exemplary embodiment of a display device DD according to the invention. 
     Referring to  FIG. 1 , the display device DD includes a display panel  100  and a driving circuit  200 . The driving circuit  200  includes a signal controller  210 , a voltage generating circuit  220 , a gate driver  230 , a data driver  240 , and a temperature sensor  250 . 
     The display panel  100  generates an image corresponding to image data applied thereto. The display panel  100  may be, but not limited to, a liquid crystal display panel. In an exemplary embodiment, as an example, the display panel  100  may employ various display panels as long as the display panels are light-receiving type display panels. 
     The display panel  100  includes a plurality of data lines DL 1  to DLm, a plurality of gate lines GL 1  to GLn, and a plurality of pixels PX. 
     The gate lines GL 1  to GLn extend in a first direction DR 1  and are arranged in a second direction DR 2  crossing the first direction DR 1 . The data lines DL 1  to DLm extend in the second direction DR 2  and are arranged in the first direction DR 1 . 
     The data lines DL 1  to DLm and the gate lines GL 1  to GLn define pixel areas, and the pixels PX are arranged in the pixel areas, respectively, and display the image.  FIG. 1  shows a pixel PX connected to a first data line DL 1  and a first gate line GL 1  as a representative example. 
     The pixel PX displays one of primary colors or one of mixed colors. The primary colors include red, green, and blue colors, and the mixed colors include white, yellow, cyan, and magenta colors, but the color displayed by the pixel PX should not be limited thereto or thereby. 
     The signal controller  210  (or timing controller) receives control signals CS and image data RGB from an external source (not shown). The signal controller  210  transmits a first control signal CONT 1  to the data driver  240  and transmits a second control signal CONT 2  to the gate driver  230 . The first control signal CONT 1  is used to control the data driver  240 , and the second control signal CONT 2  is used to control the gate driver  230 . 
     The voltage generating circuit  220  receives a power supply voltage VIN from the outside thereof and receives a clock control signal CPV and a vertical start signal STV from the signal controller  210 . 
     The voltage generating circuit  220  generates driving voltages in response to the clock control signal CPV and the vertical start signal STV and generates clock signals CKV based on the driving voltages. Each clock signal CKV may have a waveform having a gate-on voltage level and a gate-off voltage level. The clock signals CKV may be applied to the gate driver  230 . 
     The gate driver  230  transmits gate signals to the gate lines GL 1  to GLn in response to the second control signal CONT 2  from the signal controller  210 . The gate driver  230  may be integrated in a predetermined area of the display panel  100 . In an exemplary embodiment, the gate driver  230  may be implemented by a circuit including an amorphous silicon thin film transistor (“a-Si TFT”) and using an amorphous silicon gate. 
     Due to temperature characteristics of the a-Si TFT for the gate driver  230 , a difference in charge mobility may occur depending on the temperature of a-Si TFT. In particular, the mobility of the charges may be lowered at low temperature. When the gate-on voltage level applied to the gate lines GL 1  to GLn becomes lower at low temperature, a phenomenon in which the pixel PX is not sufficiently turned on occurs. The driving circuit  200  includes the temperature sensor  250  to compensate for the lowered mobility of the charges at low temperature. 
     The temperature sensor  250  may be integrated in a predetermined area of the display panel  100 . In detail, since the temperature sensor  250  is provided to compensate for the difference in charge mobility due to the temperature of the gate driver  230 , the temperature sensor  250  may be disposed adjacent to the gate driver  230 . The temperature sensor  250  receives a test voltage VT 1  and a switch signal CB from the voltage generating circuit  220  and transmits a result voltage VT 2  adjusted depending on the temperature to the voltage generating circuit  220 . 
     The voltage generating circuit  220  controls the level of the gate-on voltage and/or the gate-off voltage based on the result voltage VT 2  provided from the temperature sensor  250  and outputs the clock signal CKV to the gate driver  230 . 
     The data driver  240  drives the data lines DL 1  to DLm in response to the first control signal CONT 1  provided from the signal controller  210 . The data driver  240  may be electrically connected to one side of the display panel  100  as implemented in an independent integrated circuit or the data driver  240  may be directly mounted on the display panel  100 . In an exemplary embodiment, the data driver  240  may be implemented in a single chip or includes a plurality of chips. 
       FIG. 2  is a plan view showing an exemplary embodiment of some elements of the display device DD according to the invention. 
     Referring to  FIGS. 1 and 2 , the display panel  100  includes a display area DA and a non-display area NDA. The display area DA displays the image, and the non-display area NDA does not display the image. The non-display area NDA surrounds the display area DA. 
     The data lines DL 1  to DLm, the gate line GL 1  to GLn, and the pixels PX are arranged in the display area DA, and the gate driver  230  and the temperature sensor  250  may be arranged in the non-display area NDA. Each of the signal controller  210 , the voltage generating circuit  220 , and the data driver  240  is electrically connected to one side of the display panel  100  as implemented in an independent integrated circuit, and these components are not shown in  FIG. 2 . 
     The gate driver  230  may include a first gate driver  231  and a second gate driver  232 . In this case, the first gate driver  231  and the second gate driver  232  are disposed to be spaced apart from each other such that the display area DA is disposed between the first gate driver  231  and the second gate driver  232 , but number of gate drivers and locations thereof should not be limited thereto or thereby. That is, the gate driver  230  may include only the first gate driver  231  or the second gate driver  232  in another exemplary embodiment. 
     Each of the first gate driver  231  or the second gate driver  232  includes a plurality of shift registers. The number of the shift registers is equal to or greater than the number of the gate lines GL 1  to GLn (refer to  FIG. 1 ). In an exemplary embodiment, as an example, the first gate driver  231  includes “n” shift registers, the second gate driver  232  includes “n” shift registers, and one gate line is connected to both the first gate driver  231  and the second gate driver  232 . In addition, according to another exemplary embodiment, the first gate driver  231  includes “n/2” shift registers, the second gate driver  232  includes “n/2” shift registers, some gate lines of the gate lines GL 1  to GLn are connected to the first gate driver  231 , and the other gate lines of the gate lines GL 1  to GLn are connected to the second gate driver  232 . 
     The temperature sensor  250  may include a first temperature sensor  251  and a second temperature sensor  252 . The first temperature sensor  251  is disposed adjacent to the first gate driver  231 , and the second temperature  252  is disposed adjacent to the second gate driver  232 . The first temperature sensor  251  is disposed spaced apart from the first gate driver  231  in the first direction DR 1 , and the second temperature sensor  252  is disposed spaced apart from the second gate driver  232  in the first direction DR 1 . 
     According to another exemplary embodiment, in a case that the gate driver  230  includes only the first gate driver  231 , the second temperature sensor  252  is omitted, and in a case that the gate driver  230  includes only the second gate driver  232 , the first temperature sensor  251  is omitted. The temperature sensor  250  may be substantially simultaneously provided with the gate driver  230  in a manufacturing process. 
     According to the exemplary embodiments of the invention mentioned above, since the temperature sensor  250  is disposed adjacent to the gate driver  230 , the temperature sensor  250  may sense a variation in temperature of an area adjacent to the gate driver  230 . Accordingly, an accuracy and a reliability of the sensed temperature may be improved. 
     In the exemplary embodiment, the display panel  100  is a light-receiving type display panel, and thus a light source unit may be disposed to provide a light to the display panel  100 . The display panel  100  and the light source unit may have various positional relationships depending on products. 
       FIG. 2  shows light source units LUA, LUB, LUC, and LUD as a dotted line in areas prepared for the light source units as an example. The light source units LUA, LUB, LUC, and LUD will be referred to as first, second, third, and fourth light source units LUA, LUB, LUC, and LUD, respectively. 
     The display panel  100  has a rectangular shape including a first side  101  and a second side  101   a , which extend in the second direction DR 2 , and a third side  102  and a fourth side  102   a , which extend in the first direction DR 1 . The first light source unit LUA is disposed adjacent to the first side  101 , the second light source unit LUB is disposed adjacent to the second side  101   a , the third light source unit LUC is disposed adjacent to the third side  102 , and the fourth light source unit LUD is disposed adjacent to the fourth side  102   a.    
     The temperature in the display panel  100  may be changed depending on a distance from the light source unit. As an example, in a case that the display device DD (refer to FIG.  1 ) includes only the first light source unit LUA, the temperature in the area in which the first gate driver  231  is disposed may be higher than the temperature in the area in which the second gate driver  232  is disposed. On the other hand, in a case that the display device DD includes only the third light source unit LUC, a temperature of a third area DPAc of the display panel  100  may be the lowest among those of first, second, and third areas DPAa, DPAb, and DPAc of the display panel  100 . The first, second, and third areas DPAa, DPAb, and DPAc are sequentially defined along the second direction DR 2  as shown in  FIG. 2 . 
     The position of the temperature sensor  250  may be determined to sense the temperature that is appropriate to compensate for the charges by taking into account the variation in temperature of the first and second gate drivers  231  and  232 . This will be described in detail with reference to  FIG. 3 . 
       FIG. 3  is a plan view showing an exemplary embodiment of a display panel according to the invention, and  FIG. 4  is a block diagram showing an exemplary embodiment of a voltage generating circuit and an equivalent circuit diagram showing a temperature sensor according to the invention. 
     Referring to  FIGS. 3 and 4 , the temperature sensor  250  (refer to  FIG. 1 ) may include six temperature sensing circuits, for example, first, second, third, fourth, fifth, and sixth temperature sensing circuits  251   a ,  251   b ,  251   c ,  252   a ,  252   b , and  252   c . The first, second, and third temperature sensing circuits  251   a ,  251   b , and  251   c  are disposed adjacent to the first gate driver  231  and sequentially arranged in the second direction DR 2  in the order shown in  FIG. 3 . The fourth, fifth, and sixth temperature sensing circuits  252   a ,  252   b , and  252   c  are disposed adjacent to the second gate driver  232  and sequentially arranged in the second direction DR 2  in the order shown in  FIG. 3 . 
     The first and second gate drivers  231  and  232  are disposed on the first area DPAa, the second area DPAb, and the third area DPAc. The first and fourth temperature sensing circuits  251   a  and  252   a  are disposed in the first area DPAa of the display panel  100 , the second and fifth temperature sensing circuits  251   b  and  252   b  are disposed in the second area DPAb of the display panel  100 , and the third and sixth temperature sensing circuits  251   c  and  252   c  are disposed in the third area DPAc of the display panel  100 . 
     Each of the first, second, third, fourth, fifth, and sixth temperature sensing circuits  251   a ,  251   b ,  251   c ,  252   a ,  252   b , and  252   c  includes a plurality of diode-connected transistors. The first, second, third, fourth, fifth, and sixth temperature sensing circuits  251   a ,  251   b ,  251   c ,  252   a ,  252   b , and  252   c  may include the same number of thin film transistors.  FIG. 4  shows only the first, second, and third temperature sensing circuits  251   a ,  251   b , and  251   c . However, the fourth, fifth, and sixth temperature sensing circuits  252   a ,  252   b , and  252   c  may have the same circuit configuration as the first, second, and third temperature sensing circuits  251   a ,  251   b , and  251   c.    
     The first temperature sensing circuit  251   a  includes a plurality of thin film transistors TR 1 . Each of the thin film transistors TR 1  includes a control electrode, a first electrode, and a second electrode, and the control electrode is connected to the first electrode. The thin film transistors TR 1  may be connected to each other in series as shown in  FIG. 4 . As the temperature decreases, a threshold voltage of each of the thin film transistors TR 1  increases. In addition, since the thin film transistors TR 1  are connected to each other in series, a degree of the voltage drop due to the temperature change may be easily measured. 
     A sum of the numbers of thin film transistors TR 1 , TR 2 , and TR 3  of the first, second, and third temperature sensing circuits  251   a ,  251   b , and  251   c  adjacent to the first gate driver  231  may be equal to the number of the gate lines GL 1  to GLn (refer to  FIG. 1 ), but the relation between the sum of the numbers of thin film transistors TR 1 , TR 2 , and TR 3  and the number of the gate lines GL 1  to GLn should not be limited thereto or thereby. 
     The voltage generating circuit  220  includes a switch signal generator  221 , a voltage output and sensing unit  222 , a compensation reference determination unit  223 , and a compensator  224 . 
     The switch signal generator  221  includes a decoder that converts an n-bit binary code value input thereto to other information. The switch signal generator  221  outputs the switch signal CB (refer to  FIG. 1 ) to the temperature sensor  250  (refer to  FIG. 1 ). 
     In a case that a switch of each of the first, second, third, fourth, fifth, and sixth temperature sensing circuits  251   a ,  251   b ,  251   c ,  252   a ,  252   b , and  252   c  is separately turned on, the switch signal CB may include six information signals. On the other hand, in a case that the first and fourth temperature sensing circuits  251   a  and  252   a  arranged in the first area DPAa are substantially simultaneously turned on, the second and fifth temperature sensing circuits  251   b  and  252   b  arranged in the second area DPAb are substantially simultaneously turned on, and the third and sixth temperature sensing circuits  251   c  and  252   c  arranged in the third area DPAc are substantially simultaneously turned on, the switch signal CB may include three information signals. The first temperature sensing circuit  251   a  includes first switches SW 1  and SW 1   a , the second temperature sensing circuit  251   b  includes second switches SW 2  and SW 2   a , and the third temperature sensing circuit  251   c  includes third switches SW 3  and SW 3   a . The voltage output and sensing unit  222  outputs the test voltage VT 1  to the temperature sensor  250  (refer to  FIG. 1 ). In a case that the first switches SW 1  and SW 1   a  are turned on in response to the switch signal CB, the test voltage VT 1  is applied to the first temperature sensing circuit  251   a . In a case that the second switches SW 2  and SW 2   a  are turned on in response to the switch signal CB, the test voltage VT 1  is applied to the second temperature sensing circuit  251   b . In a case that the third switches SW 3  and SW 3   a  are turned on in response to the switch signal CB, the test voltage VT 1  is applied to the third temperature sensing circuit  251   c.    
     The voltage output and sensing unit  222  receives the result voltage VT 2 . The result voltage VT 2  has a voltage level dropped from the test voltage VT 1  by the sum of the threshold voltages of the thin film transistors of the corresponding temperature sensing circuit. 
     The compensation reference determination unit  223  includes comparators. The compensation reference determination unit  223  receives a plurality of result voltages VT 2  from the first, second, third, fourth, fifth, and sixth temperature sensing circuits  251   a ,  251   b ,  251   c ,  252   a ,  252   b , and  252   c  and determines the result voltage VT 2  having the largest voltage difference from the test voltage VT 1  among the result voltages VT 2  as a compensation reference. 
     The compensator  224  controls the level of the gate-on voltage and/or the gate-off voltage based on the determined result of the compensation reference determination unit  223  and outputs the clock signal CKV to the first and second gate drivers  231  and  232 . The compensator  224  may determine a compensation level of the gate-on voltage and/or the gate-off voltage depending on the voltage difference between the test voltage VT 1  and the result voltage VT 2  using a look-up table or by calculating a voltage between predetermined maximum and minimum values of the compensation level by a linear interpolation or other operations. However, the compensation operation by the compensator  224  is not limited thereto. It may be changed in various ways. 
       FIG. 5A  is a view showing a ground voltage GND, the test voltage VT 1 , and the result voltage VT 2  according to an exemplary embodiment of the invention. In detail, the result voltage VT 2  indicates the result voltage measured when the third light source unit LUC (refer to  FIG. 2 ) is disposed in the area adjacent to the third side  102  (refer to  FIG. 2 ) of the display panel  100 . 
     Referring to  FIGS. 2, 3, and 5A , the first and fourth temperature sensing circuits  251   a  and  252   a  are arranged in the area nearest to the third light source unit LUC (refer to  FIG. 2 ), and the third and sixth temperature sensing circuits  251   c  and  252   c  are arranged in the area farthest from the third light source unit LUC (refer to  FIG. 2 ). 
     Among voltage drop amounts VD 1 , VD 2 , VD 3 , VD 1   a , VD 2   a , and VD 3   a  of the first, second, third, fourth, fifth, and sixth temperature sensing circuits  251   a ,  251   b ,  251   c ,  252   a ,  252   b , and  252   c , the voltage drop amount VD 3  and VD 3   a  of the third and sixth temperature sensing circuits  251   c  and  252   c  is the largest voltage drop amount. 
     That is, the temperature of the areas in which the third and sixth temperature sensing circuits  251   c  and  252   c  are respectively disposed is the lowest temperature. Accordingly, the temperature compensation may be performed based on the voltage drop amounts VD 3  and VD 3   a  of the third and sixth temperature sensing circuits  251   c  and  252   c  to compensate for the lowered mobility of charges of the thin film transistors in the first and second gate drivers  231  and  232 . 
       FIG. 5B  is a view showing the ground voltage GND, the test voltage VT 1 , and a result voltage VT 2   a  according to another exemplary embodiment of the invention. In detail, the result voltage VT 2   a  indicates the result voltage measured when the first light source unit LUA (refer to  FIG. 2 ) is disposed in the area adjacent to the first side  101  (refer to  FIG. 2 ) of the display panel  100 . 
     Referring to  FIGS. 2, 3, and 5B , the first, second, and third temperature sensing circuits  251   a ,  251   b , and  251   c  are arranged in the area nearest to the first light source unit LUA (refer to  FIG. 2 ), and the fourth, fifth, and sixth temperature sensing circuits  252   a ,  252   b , and  252   c  are arranged in the area farthest from the first light source unit LUA (refer to  FIG. 2 ). 
     Among voltage drop amounts VD 1 , VD 2 , VD 3 , VD 1   a , VD 2   a , and VD 3   a  of the first, second, third, fourth, fifth, and sixth temperature sensing circuits  251   a ,  251   b ,  251   c ,  252   a ,  252   b , and  252   c , the voltage drop amount VD 1   a , VD 2   a , and VD 3   a  of the fourth, fifth, and sixth temperature sensing circuits  252   a ,  252   b , and  252   c  is the largest voltage drop amount. 
     That is, the temperature of the areas in which the fourth, fifth, and sixth temperature sensing circuits  252   a ,  252   b , and  252   c  are respectively disposed is the lowest temperature. Accordingly, the temperature compensation may be performed based on the voltage drop amounts VD 1   a , VD 2   a , and VD 3   a  of the fourth, fifth, and sixth temperature sensing circuits  252   a ,  252   b , and  252   c  to compensate for the lowered mobility of charges of the thin film transistors in the first and second gate drivers  231  and  232 . 
     According to the exemplary embodiments above, although the positional relationship between the display panel  100  and the light source unit is changed in various ways, the voltage levels of the gate-on and -off voltages are compensated based on the result voltage having the largest voltage drop amount among the result voltages sensed by the temperature sensing circuits. That is, the voltage levels of the gate-on and -off voltages are adjusted to compensate for the lowered mobility of charges in the gate drivers of the lowest temperature, and thus the phenomenon in which the pixel PX is not sufficiently turned on is effectively prevented from occurring. 
       FIG. 6  is a flowchart showing an exemplary embodiment of a compensation operation of the gate driver  230  according to the invention. 
     Referring to  FIGS. 1 and 6 , the power of the display device DD is turned on (S 10 ). The voltage generating circuit  220  outputs the test voltage VT 1  to the temperature sensor  250  after a predetermined time and receives the result voltages VT 2  (S 20 ). The predetermined time may be an aging time for stabilizing the liquid crystal molecules in the display panel  100  by giving an electrical signal to the display panel  100  during a certain time. 
     The voltage generating circuit  220  compares the voltage drops of temperature sensing areas (S 30 ). The temperature sensing areas correspond to the areas in which the temperature sensing circuits are disposed, and the area in which the thin film transistors are connected to each other in series is defined as one temperature sensing area. 
     The voltage generating circuit  220  performs the temperature compensation operation based on the maximum value among the voltage drops (S 40 ). Accordingly, since the voltage levels of the gate-on and -off voltages are adjusted to compensate for the lowered mobility of charges in the gate drivers of the lowest temperature, the mobility of the charges of the thin film transistors in the gate driver  230  at low temperature may be compensated. Accordingly, the phenomenon in which the pixel PX is not sufficiently turned on may be effectively prevented from occurring. 
       FIG. 7  is a plan view showing another exemplary embodiment of a display panel according to the invention. In  FIG. 7 , the same reference numerals denote the same elements in  FIG. 3 , and thus detailed descriptions of the same elements will be omitted. 
     Referring to  FIGS. 1 and 7 , a temperature sensor  250  includes a first temperature sensing circuit  251   d , a second temperature sensing circuit  252   d , and a third temperature sensing circuit  251   e.    
     The first temperature sensing circuit  251   d  is disposed in a first area DPAa, the second temperature sensing circuit  252   d  is disposed in a second area DPAb, and the third temperature sensing circuit  251   e  is disposed in a third area DPAc. 
     At least one temperature sensing circuit of the first, second, and third temperature sensing circuits  251   d ,  252   d , and  251   e  is disposed adjacent to the first gate driver  231 , and at least one temperature sensing circuit of remaining temperature sensing circuits is disposed adjacent to the second gate driver  232 . 
     In  FIG. 7 , the first and third temperature sensing circuits  251   d  and  251   e  are disposed adjacent to the first gate driver  231 , and the second temperature sensing circuit  252   d  is disposed adjacent to the second gate driver  232 , but locational relationships between temperature sensing circuits and gate drivers should not be limited thereto or thereby. 
     In another exemplary embodiment, the first temperature sensing circuits  251   d  disposed in the first area DPAa and the second temperature sensing circuits  252   d  disposed in the second area DPAb may be disposed adjacent to the first gate driver  231 , and the third temperature sensing circuit  251   e  disposed in the third area DPAc may be disposed adjacent to the second gate driver  232 . In still another exemplary embodiment, the first temperature sensing circuit  251   d  disposed in the first area DPAa may be disposed adjacent to the first gate driver  231 , and the second temperature sensing circuits  252   d  disposed in the second area DPAb and the third temperature sensing circuits  251   e  disposed in the third area DPAc may be disposed adjacent to the second gate driver  232 . 
     Referring to  FIGS. 2 and 7  again, although the display device DD (refer to  FIG. 1 ) includes at least one of the first light source unit LUA, the second light source unit LUB, the third light source unit LUC, and the fourth light source unit LUD, the lowest temperature area may be sensed by the first, second, and third temperature sensing circuits  251   d ,  252   d , and  251   e . Accordingly, the voltage level of the clock signal CKV applied to the first and second gate drivers  231  and  232  may be corrected based on temperature information of the lowest temperature area. As a result, the phenomenon in which the pixel PX (refer to  FIG. 1 ) is not sufficiently turned on may be effectively prevented from occurring. 
       FIG. 8  is a plan view showing still another exemplary embodiment of a display panel according to the invention. In  FIG. 8 , the same reference numerals denote the same elements in  FIG. 3 , and thus detailed descriptions of the same elements will be omitted. 
     Referring to  FIGS. 1 and 8 , a temperature sensor  250  includes first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, and tenth temperature sensing circuits  251   f ,  251   g ,  251   h ,  251   i ,  251   j ,  252   f ,  252   g ,  252   h ,  252   i , and  252   j . The first, second, third, fourth, and fifth temperature sensing circuits  251   f ,  251   g ,  251   h ,  251   i , and  251   j  are disposed adjacent to the first gate driver  231 , and the sixth, seventh, eighth, ninth, and tenth temperature sensing circuits  252   f ,  252   g ,  252   h ,  252   i , and  252   j  are disposed adjacent to the second gate driver  232 . 
     The display panel is divided into first, second, third, fourth, and fifth areas DPA 1 , DPA 2 , DPA 3 , DPA 4 , and DPA 5 , and the first, second, third, fourth, and fifth areas DPA 1 , DPA 2 , DPA 3 , DPA 4 , and DPA 5  are sequentially defined in the second direction DR 2 . 
     The first, second, third, fourth, and fifth temperature sensing circuits  251   f ,  251   g ,  251   h ,  251   i , and  251   j  are disposed in the first, second, third, fourth, and fifth areas DPA 1 , DPA 2 , DPA 3 , DPA 4 , and DPA 5  respectively, and the sixth, seventh, eighth, ninth, and tenth temperature sensing circuits  252   f ,  252   g ,  252   h ,  252   i , and  252   j  are disposed in the first, second, third, fourth, and fifth areas DPA 1 , DPA 2 , DPA 3 , DPA 4 , and DPA 5  respectively. 
     The number of the temperature sensing circuits may be changed depending on a size of the display panel  100 . As an example, as the size of the display panel  100  increases, the number of the temperature sensing circuits may increase. In addition, in order to sense the lowest temperature area in more detail, the display panel may be divided into more areas. Accordingly, the number of the temperature sensing circuits may increase. The number of the temperature sensing circuits should not be limited to the above-mentioned exemplary embodiments and may be changed in various ways. 
     As described above, optimal exemplary embodiments have been disclosed in the drawings and the specification. Although specific terms have been used herein, these are only intended to describe the exemplary embodiments above and are not intended to limit the meanings of the terms or to restrict the scope of the accompanying claims. Accordingly, those skilled in the art will appreciate that various modifications and other equivalent exemplary embodiments are possible from the above exemplary embodiments. Therefore, the scope of the claims should be defined by the technical spirit of the specification.