Patent Publication Number: US-10777135-B2

Title: Controlling circuit for compensating a display device and compensation method for pixel aging

Description:
TECHNICAL FIELD 
     The disclosure relates to a display method, and in particular, to a compensation method for pixel aging and a controlling circuit for compensating a display device. 
     BACKGROUND 
     With the rapid advance and continual progress in technology, the organic light emitting diode (OLED) technology has been provided and widely used in various applications such as TV, computer monitor, notebook computer, mobile phone or PDA. In general, the OLED display includes many OLED pixel circuits arranged in the form of a matrix, and each OLED pixel circuit includes an OLED element and a corresponding driving circuit. However, pixels of the conventional OLED device are controlled by thin-film transistors (TFT). Consequently, the pixels of the conventional OLED device inherit the disadvantages of the TFTs and would be aged along with using time. 
     SUMMARY 
     An aspect of the disclosure provides a compensation method for pixel aging. The compensation method is applicable to a controlling circuit of a display device having a display panel and comprises: receiving a display content by the controlling circuit; predicting by the controlling circuit an aging of each of a plurality of pixels of the display panel resulting from the display content in order to obtain an aging prediction; generating a display data by the controlling circuit to compensate the display panel according to the aging prediction; and outputting the display data by the controlling circuit. 
     Another aspect of the disclosure provides a controlling circuit for compensating a display device. The controlling circuit includes a receiving circuit, a calculation circuit and an output circuit. The receiving circuit is configured to receive a display content. The calculation circuit is coupled to the receiving circuit and configured to predict an aging of each of a plurality of pixels of a display panel of the display device resulting from the display content in order to obtain an aging prediction, and generate a display data to compensate the display panel according to the aging prediction. The output circuit is coupled to the calculation circuit and configured to output the display data. 
     To make the aforementioned more comprehensible, several embodiments accompanied with drawings are described in detail as follows. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. 
         FIG. 1A  illustrates a block diagram of a display device according to an embodiment of the disclosure. 
         FIG. 1B  illustrates a block diagram of a controlling circuit according to an embodiment of the disclosure. 
         FIG. 2  illustrates a flowchart of a compensation method according to an embodiment of the disclosure. 
         FIG. 3  illustrates a schematic diagram of an aging model according to an embodiment of the disclosure. 
         FIG. 4A  and  FIG. 4B  illustrate schematic diagrams of predicting an aging of each pixel of the display panel resulting from the display content according to an embodiment of the disclosure. 
         FIG. 5  illustrates a schematic diagram of compensating the display content by using the predicted aging resulting from the display content and the compensation values stored in the storage according to an embodiment of the disclosure. 
         FIG. 6  illustrates a flowchart of a compensation method according to an embodiment of the disclosure. 
         FIG. 7A ,  FIG. 7B  and  FIG. 7C  illustrate schematic diagrams of a partial sensing operation according to an embodiment of the disclosure. 
         FIG. 8  illustrates a schematic diagram of sensing the aging of the over-aged pixel by performing the partial sensing operation on the display panel according to an embodiment of the disclosure. 
         FIG. 9  illustrates a schematic diagram of compensating the display panel by using the sensed aging of the over-aged pixel and the compensation value stored in the storage according to an embodiment of the disclosure. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1A  illustrates a block diagram of a display device according to an embodiment of the disclosure. Referring to  FIG. 1A , the display device  100  includes a controlling circuit  110 , a storage  120  and a display panel  130 , where the controlling circuit  110  is coupled to the storage  120  and the display panel  130 . 
     The controlling circuit  110  is configured to receive an externally input display content such as RGB data, execute instructions for carrying out the compensation method of the embodiments of the disclosure in order to output display data to a display driver of the display panel  130 , such that the display driver may drive the display panel  130  to properly display images according to the display data output by the controlling circuit  110 . In some embodiment, the controlling circuit  110  is implemented as including a time controller (TCON). In some embodiments, the controlling circuit  110  is implemented as including the time controller and further including a processor such as a central processing unit (CPU), other programmable general-purpose or specific-purpose microprocessors, a digital signal processor (DSP), a programmable controller, an application specific integrated circuit (ASIC), a programmable logic device (PLD), other similar devices, or a combination thereof, for example. It should be noted that the disclosure is not limited thereto. 
       FIG. 1B  illustrates a block diagram of a controlling circuit according to an embodiment of the disclosure. Referring to  FIG. 1B , in some embodiments, the controlling circuit  110  includes a receiving circuit  111 , a calculation circuit  113 , an output circuit  115 , a memory circuit  117  and a sensing control circuit  119 , wherein the receiving circuit  111 , the output circuit  115 , the memory circuit  117  and the sensing control circuit  119  are coupled to the calculation circuit  113 . In some embodiment, the receiving circuit  111 , the calculation circuit  113  and the memory circuit  117  are implemented in the processor of the controlling circuit  110 , and the output circuit  115  and the sensing control circuit  119  are implemented in the time controller of the controlling circuit  110 , but which is not limited herein. These circuits in the controlling circuit  110  cooperates to compensate the display device  100 . Details of the compensation method will be introduced in the following descriptions. 
     The storage  120  is configured to store data needed for the compensation method of the embodiments of the disclosure. The storage  120  is, for example, any type of fixed or portable random access memory (RAM), read-only memory (ROM), non-volatile memory (NVM), or similar components, or a combination of the above components. It is noted that the disclosure in not limited thereto. In some embodiments, the storage  120  includes not only the NVM but also the RAM for accelerating the process speed. 
     The display panel  130  is configured to display images through a plurality of pixels thereof. The display panel  130  is, for example, an organic light emitting display (OLED) panel, an active matrix organic light emitting display (AMOLED) panel, or other types of panel in which the pixels may age with using time. It is noted that the disclosure is not limited thereto. 
     In some embodiments, the display panel  130  is an OLED panel in which each pixel is implemented as at least an OLED pixel circuit. The illuminance of each OLED pixel circuit is controlled by a current flowing through a thin-film transistor (TFT) and the current flowing through a TFT is in accordance with the following formula:
 
 I   TFT   =K ( V   gs   −V   th ) 2 ,
 
     where I TFT  is the current flowing through the TFT; K is a constant associated with the physical structure of the TFT; V gs  is a bias difference between gate and source of the TFT; and V th  is the threshold voltage of the TFT. It is noted that the threshold voltage V th  may increase with the using time and the OLED pixel circuit is therefore being aged. In order to maintain the illuminance, the bias difference V gs  applied to the TFT needs to be increased together with the threshold voltage V th . That is to say, the processor  110  may compensate the aged pixel as long as the increment of the threshold voltage V th  is known (e.g., by predicting or by sensing). 
       FIG. 2  illustrates a flowchart of a compensation method according to an embodiment of the disclosure. Noted that the compensation method in embodiments of  FIG. 2  is applicable to the display device  100  as illustrated in  FIG. 1A  and the controlling circuit  110  as illustrated in  FIG. 1B , therefore it will be described accompanying with the elements of  FIG. 1A  and  FIG. 1B  in the following descriptions. 
     Referring to  FIG. 2 , in step S 11 , the controlling circuit  110  determines whether the display panel  130  is on or off. In some embodiments, the display device  100  is configured in a mobile electronic device such as a smart phone. As such, the display panel  130  may be turned on, for example, when a user wakes the mobile electronic device through a power button thereof or when the controlling circuit  110  wakes the display panel  130  in response to an incoming signal in order to notify the user of the incoming signal. On the other hands, the display panel  130  may be turned off, for example, when the user blacks the display panel  130  through the power button or when the mobile electronic device idles for a predetermined time. However, it should be noted that the disclosure is not limited thereto. 
     If the display panel  130  is off, the flow proceeds to step S 12  for sensing the aging of each pixel of the display panel  130 . In step S 12 , the controlling circuit  110  senses an aging of each pixel of the display panel  130  by performing a full sensing operation on the display panel  130 , in order to obtain an aging value of each pixel. The aging value is, for example, a voltage increment ΔV th  of the threshold value V th . In step S 13 , the controlling circuit  110  stores the aging value of each pixel into the storage  120 . 
     In some embodiments, the sensing control circuit  119  of the controlling circuit  110  in the step S 12  may control to sequentially charge the pixels of the display panel  130  and detect the threshold voltage V th  of each pixel, so as to obtain the voltage increment ΔV th  of each pixel. Afterwards, the controlling circuit  110  in the step S 13  may store the voltage increment ΔV th  of each pixel into the NVM of the storage  120  in form of, for example, a compensation table in which each entry is configured to record the voltage increment ΔV th  of each pixel of the display panel  130 . 
     In some embodiments, the controlling circuit  110  stores the compensation table into the NVM of the storage  120  only when the full sensing operation is finished. If the controlling circuit  110  detects the display panel  130  is turned on during the full sensing operation, the full sensing operation fails and the step S 13  is not entered. That is, no aging value sensed by the full sensing operation is stored into the NVM of the storage  120  if the full sensing operation fails. 
     If the display panel  130  is on, the flow proceeds to step S 14  for receiving a display content. In some embodiments, the receiving circuit  111  of the controlling circuit  110  receives a display content from a device external to the display device  100 . The display content includes, for example, a plurality of consecutive image frames to be sequentially displayed. 
     In step S 15 , the controlling circuit  110  predicts the aging of each pixel resulting from the display content in order to obtain an aging prediction. Specifically, pixels of the display panel  130  may be gradually aged while displaying the display content, and the controlling circuit  110  does not sense the aging of each pixel as in the step S 12  but predicts the aging of each pixel resulting from the display content according to an aging model. The aging model indicates how the pixels of the display panel  130  decays when displaying, and it is associated with intrinsic characteristics of the pixels such as carrier mobility, threshold voltage, etc. In some embodiment, the aging model is established and stored into the NVM of the storage  120  when the display device  100  leaving the factory. As such, the aging of each pixel resulting from the display content, which is the aging prediction, can be calculated on the basis of the aging model. 
     In some embodiments, the aging model can be represented as:
 
Δ V   th_pre =β(display code−γ) α ,
 
     where the display code is a number positively related to the illuminance of an image frame of the display content, for example, an R, G or B color code of the image frame each in a range of [0, 255]; ΔV th_pre  is a predicted voltage increment of the threshold voltage V th  resulting from the image frame; and α, β and γ are constants associated with intrinsic characteristics of each pixel and are obtained according to historical or experimental data, for example. 
     It is appreciated that the form of the aging model is not limited as above. In other embodiments, the aging model can be a linear distribution, an exponential distribution, or any other distributions. Referring to  FIG. 3 , according to the intrinsic characteristics of the pixels, the aging model can be linear as the aging model AM 1 , exponential as the aging model AM 2 , or arbitrary as the aging model AM 3 , for example. In some embodiments, the aging model may further be a function of time, which is not limited herein. It is appreciated that calculations using the aging model can be implemented by circuit logics, lookup tables, etc., which is not limited herein. 
     In some embodiments, by using such aging model, the aging prediction can be obtained by inputting data (e.g., the display code) of each image frame of the display content into the aging model for calculating the aging of each pixel resulting from each image frame and accumulating the aging of each pixel resulting from each image frame. 
     Specifically, when the receiving circuit  111  receives the 1 st  image frame, the aging of each pixel resulting from the 1 st  image frame of the display content (e.g., the aging prediction of the first image frame) may be calculated by the calculation circuit  113  by inputting data of the 1 st  image frame into the aging model. The calculated aging resulting from the 1 st  image frame is then stored (e.g., as an aging table) in the RAM of the storage  120  in some embodiments. When the receiving circuit  111  receives the 2 nd  image frame, the accumulated aging of each pixel resulting from the first two image frames of the display content (e.g., the aging prediction of the first two image frames) may be calculated by the calculation circuit  113  by inputting data of the 2 nd  image frame into the aging model to obtain the aging of each pixel resulting from the 2 nd  image frame, and adding the aging resulting from the 2 nd  image frame to the aging resulting from the 1 st  image frame stored in the RAM of the storage  120 . The accumulated aging of the 2 nd  image frame is then stored in the RAM of the storage  120  (e.g., in the aging table) in some embodiments. When the receiving circuit  111  receives the 3 rd  image frame, the accumulated aging of each pixel resulting from the first three image frames of the display content (e.g., the aging prediction of the first three image frames) may be calculated by the calculation circuit  113  by inputting data of the 3 rd  image frame into the aging model to obtain the aging of each pixel resulting from the 3 rd  image frame, and adding the aging resulting from the 3 rd  image frame to the accumulated aging of the 2 nd  image frame stored in the RAM of the storage  120 . The accumulated aging of the 3 rd  image frame is then stored in the RAM of the storage  120  (e.g., in the aging table) in some embodiments. Deduced by analogy, when the receiving circuit  111  receives a current image frame which is, for example, the n th  image frame, the accumulated aging of each pixel resulting from the first n image frames of the display content (e.g., the aging prediction of the first n image frames) may be calculated by the calculation circuit  113  by inputting data of the n th  image frame f n  into the aging model to obtain the aging of each pixel resulting from the n th  image frame a n , and adding the aging of each pixel resulting from the n th  image frame a n  to the accumulated aging of the (n−1) image frames S an-1  stored in the RAM of the storage  120  as shown in  FIG. 4A  and  FIG. 4B , and the accumulated aging of the n th  image frame S an  is then stored in the RAM of the storage  120  (e.g., in the aging table) in some embodiments. 
     In some embodiments, for accelerating the calculation of the aging prediction, a lookup table including a mapping between a display code and an aging is pre-stored in the memory circuit  117  of the controlling circuit  110  (e.g., a cache of the processor of the controlling circuit). As such, the aging of each pixel resulting from the n th  image frame can be calculated faster by consulting the lookup table in the memory circuit  117  according to data of the n th  image frame, instead of inputting the data of the n th  image frame into the aging model. The lookup table may be, for example, established according to the aging model, stored in the NVM of the storage  120  (e.g., when the display device  110  leaves the factory), and loaded into the memory circuit  117  before the step  15 . However, the disclosure is not limited thereto. 
     It is noted that the grey scales illustrated in the figures are corresponding to the illuminance or the increment of the threshold voltage. Referring to  FIG. 4A  and  FIG. 4B , the predicted increment of the threshold voltage a n  is calculated by inputting the n th  image frame f n  into the aging model or by consulting the lookup table which is establish based on the aging model according to the n th  image frame f n , and an accumulated aging of the n th  image frame Sa n  (e.g., the aging prediction of the first n image frames) is calculated by adding the predicted increment of the threshold voltage a n  to the accumulated aging of the (n−1) th  image frame Sa n-1  stored in the RAM of the storage  120 . 
     In step S 16 , the controlling circuit  110  determines whether the predicted aging resulting from the display content exceeds a critical aging. Specifically, if the predicted aging resulting from the display content is too obvious to be ignored by the user, the display panel  130  needs to be compensated by using not only the aging value of each pixel obtained when the display panel  130  is off and stored in the NVM of the storage  120  but also the predicted aging resulting from the display content. Otherwise, the aging values stored in the NVM of the storage  120  is enough for compensating the display panel  130 . As such, the calculation circuit  113  of the controlling circuit  110  determines whether the predicted aging resulting from the display content exceeds the critical aging in the step S 16 . 
     In some embodiments, the calculation circuit  113  sets an aging threshold as the critical aging and compares the predicted aging resulting from the display content with the aging threshold. If there is any pixel of which the predicted aging resulting from the display content is higher than the aging threshold, which means that the predicted aging resulting from the display content is too obvious to be ignored by the user, then the calculation circuit  113  determines that the predicted aging resulting from the display content exceeds the critical aging and the flow proceeds to step S 18 . Otherwise, the calculation circuit  113  determines that the predicted aging resulting from the display content does not exceed the critical aging and the flow proceeds to step S 17 . 
     In the step S 18 , the controlling circuit  110  generates a display data to compensate the pixels of the display panel  130  by using the predicted aging of each pixel resulting from the display content and the aging values stored in the storage  120 . In the step S 19 , the controlling circuit  110  outputs the display data. In some embodiments, as shown in  FIG. 5 , the aging table stores the accumulated aging Sa n  of each pixel resulting from the current image frame f n , and the compensation table stores the voltage increment ΔV th  of each pixel before the display panel is on. The calculation circuit  113  of the controlling circuit  110  may generate a display data that makes a display driver of the display panel  130  to drive the display panel  130  to display the current image frame or a next image frame while raising the bias difference between gate and source of each pixel by an addition of the accumulated aging Sa n  and the voltage increment ΔV th  of each pixel, so as to compensate the display panel  130 . Afterwards, the output circuit  115  of the controlling circuit  110  may output the display data, for example, to the display driver of the display panel  130  such that the display panel  130  can be compensated when displaying the current image frame or the next image frame according to the display data. 
     In the step S 17 , the controlling circuit  110  generates a display data to compensate the pixels of the display panel  130  by using the aging values stored in the storage  120 . In the step S 19 , the controlling circuit  110  outputs the display data. In some embodiments, the compensation table stores the voltage increment ΔV th  of each pixel, therefore the calculation circuit  113  of the controlling circuit  110  may generate a display data that makes a display driver of the display panel  130  to drive the display panel  130  to display the current image frame while raising the bias difference between gate and source of each pixel by the voltage increment ΔV th  of each pixel, so as to compensate the display panel  130 . Afterwards, the output circuit  115  of the controlling circuit  110  may output the display data, for example, to the display driver of the display panel  130  such that the display panel  130  can be compensated when displaying the current image frame according to the display data. 
     In some embodiments, the processor of the controlling circuit  110  loads the compensation table stored in the NVM of the storage  120  into the RAM of the storage  120  after determining that the display panel  130  is on in the step S 11  and before the flow proceeds to the step S 17  or the step S 18 , such that data of the compensation table can be quickly used in the step S 17  or the step S 18 . 
     It is noted that the compensation method illustrated in embodiments of  FIG. 2  allows the aging resulting from the display content be compensated timely during the display panel  130  displaying images corresponding to the display content. Therefore, a critical aging occurred during the user using the display panel  130  is timely compensated. As such, the user is not supposed to perceive the aging on the display panel  130  when adopting the introduced compensation method. 
       FIG. 6  illustrates a flowchart of a compensation method according to another embodiment of the disclosure. Noted that the compensation method in embodiments of  FIG. 6  is applicable to the display device  100  as illustrated in  FIG. 1A  and the controlling circuit  110  as illustrated in  FIG. 1B , therefore it will be described accompanying with the elements of  FIG. 1A  and  FIG. 1B  in the following descriptions. Also noted that steps S 21  to S 27  are similar to the step S 11  to S 17  described in the embodiments of  FIG. 2 , therefore details of steps S 21  to S 27  are not repeated herein. Instead of generating the display data for compensating the pixels on the basis of a predicted aging, the controlling circuit  110  senses the aging of the pixels that have a predicted aging exceeds the critical aging and generates the display data for compensating the pixels on the basis of the actually sensed aging in the embodiments of  FIG. 6 . As such, more accurate compensation can be performed. 
     Referring to  FIG. 6 , the flow proceeds to step S 28  after it is determined in step S 26  by the calculation circuit  113  that the predicted aging of at least one pixel resulting from the display content exceeds the critical aging. The calculation circuit  113  predicts an over-aged pixel among the pixels in the step S 28 , and the sensing control circuit  119  senses the aging of the over-aged pixel by performing a partial sensing operation on the display panel in step S 29 . Specifically, the over-aged pixel is a pixel of which the predicted aging resulting from the display content exceeds the critical aging or the predicted voltage increment ΔV th_pre  exceeds the aging threshold set by the calculation circuit  113 . For shortening the sensing time, the sensing control circuit  119  only senses the aging of part of the pixels including the over-aged pixels instead of sensing all pixels of the display panel  130 . 
     In some embodiments, there are multiple over-aged pixels on the display panel  130 , the sensing control circuit  119  performs the partial sensing operation on the display panel  130  for sensing the aging of the over-aged pixels. For instance, as shown in  FIG. 8 , all pixels of the display panel  130  may be divided into two groups, i.e., the first group G 1  and the second group G 2 , where the first group G 1  includes all of the over-aged pixels and the second group G 2  does not include any over-aged pixel. The sensing control circuit  119  then senses the aging of the pixels in the first group G 1 , in order to obtain a partial sensing result ΔV th_p  which indicates the aging (e.g., increment of the threshold voltage) of each pixel in the first group G 1 . 
     It is noted that the partial sensing operation senses fewer pixels than (or same pixels as) the full sensing operation, therefore the operation time of the partial sensing operation is not longer than the operation time of the full sensing operation. It is also noted that since the partial sensing operation is performed during a display time of the display content and should not be noticed by the user, it needs to shorten the sensing time for sensing each pixel and its accuracy is sacrificed in some cases. Therefore, the accuracy of the full sensing operation is higher than the accuracy of the partial sensing operation in some embodiments. 
       FIG. 7A ,  FIG. 7B  and  FIG. 7C  illustrate schematic diagrams of a partial sensing operation according to an embodiment of the disclosure. For illustrating the partial sensing operation, as shown in  FIG. 7A , it is assumed that the size of the display panel  130  is 3840 pixels*2160 lines, the frame rate is 120 Hz, and a blanking time between each two of the consecutive image frames of the display content is 40 line-time. As such, when displaying images corresponding to the display content, it takes about 8.3 ms (i.e., 1 s/120) per image frame, and the line-time is about 3.77 μs (i.e., 8.3 ms/(2160+40)) per line. For not being noticed by the user, the partial sensing operation has to be finished in a time shorter than the blanking time (i.e., 40*3.77 μs). 
     In some embodiments, the partial sensing operation can be an in-display sensing operation which is performed in the frame time of the current image frame as shown in  FIG. 7B . Specifically, when an over-aged pixel is on the N th  line, the sensing control circuit  119  may sense the aging of the over-aged pixel on the N th  line after updating data of the N th  line and before updating data of the (N+1) th  line. The operation time (e.g., M line-time) for sensing the over-aged pixel on the N th  line is not longer than the original blanking time (e.g., 40 line-time), therefore some time (e.g., (40-M) line-time) between the current image frame and a next image frame can be reserved. As such, the partial sensing operation can be completed and the partial sensing result can be obtained before displaying the next image frame, without being noticed by the user. 
     In some embodiments, the partial sensing operation can be an in-blanking sensing operation which is performed in the blanking time between the current image frame and the next current frame as shown in  FIG. 7C . Specifically, the in-blanking sensing operation is performed after the current image framed is displayed and before the next image frame starts being displayed. When an over-aged pixel is on the N th  line, the sensing control circuit  119  locates and sets the line to be sensed (i.e., the N th  line) before starting to sense the over-aged pixel on the N th  line. Comparing to the aforementioned in-display sensing operation, the in-blanking sensing operation needs an additional time for locating and setting the N th  line. For not being noticed by the user, the total time of said additional time for locating and setting the N th  line and the sensing time (e.g., M line-time) for sensing the over-aged pixel on the N th  line is not longer than the original blanking time (e.g., 40 line-time). As such, the partial sensing operation can be completed and the partial sensing result can be obtained before displaying the next image frame, without being noticed by the user. 
     After the partial sensing result is obtained, in step S 30 , the calculation circuit  113  of the controlling circuit  110  may generate a display data to compensate the pixels of the display panel by using the sensed aging of the over-aged pixel and the aging values stored in the storage. In the step S 31 , the output circuit  115  of the controlling circuit  110  outputs the display data. In some embodiments, the pixels of the display panel  130  are divided into the first group G 1  and the second group G 2 , and the partial sensing result ΔV th_p  indicating the aging (e.g., increment of the threshold voltage) of each pixel in the first group G 1  is obtained. The calculation circuit  113  then generate a display data for driving the display panel  130  to display images corresponding to the display content. As shown in  FIG. 9 , the display data is generated for compensating the pixels in the first group G 1  by using the partial sensing result ΔV th_p  and compensating the pixels in the second group G 2  by using the aging values stored in the NVM of the storage  120  (e.g., the compensation table stores the voltage increment ΔV th  of each pixel). Afterwards, the output circuit  115  of the controlling circuit  110  may output the display data, for example, to the display driver of the display panel  130  such that the display panel  130  can be compensated when displaying images according to the display data. 
     Referring to  FIG. 9 , for the first group G 1 , the calculation circuit  113  may generate the display data that makes a display driver of the display panel  130  to drive the pixels in the first group G 1  to display the next image frame by raising the bias difference between gate and source of each pixel in the first group G 1  by the partial sensing result ΔV th_p . On the other hand, for the second group G 2 , the display data makes the display driver of the display panel  130  to drive the pixels in the second group G 2  to display the next image frame by raising the bias difference between gate and source of each pixel in the second group G 2  by the voltage increment ΔV th  of each pixel in the second group G 2 . Afterwards, the output circuit  115  of the controlling circuit  110  may output the display data, for example, to the display driver of the display panel  130  such that all pixels of the display panel  130  can be compensated when displaying the next image frame according to the display data. 
     It is noted that the compensation method illustrated in embodiments of  FIG. 6  performs a fast sensing on the pixels that are predicted to be over-aged without being noticed by the user, which therefore allows the aging resulting from the display content be compensated timely and accurately during the display panel  130  displaying images corresponding to the display content. Therefore, a critical aging occurred during the user using the display panel  130  is timely and accurately compensated. As such, the user is not supposed to perceive the aging on the display panel  130  when adopting the introduced compensation method as well. 
     In summary, the compensation method for pixel aging and the controlling circuit for compensating the display device in embodiments of the disclosure predict an aging resulting from a display content, and compensate pixels of the display panel according to the predicted aging. As such, compensation for the aging resulting from the display content can be completed during the display time of the display content, thus the display quality can be maintained. In some embodiments, an actual aging of pixels predicted to be over-aged due to the current image frame is rapidly sensed by using a partial sensing operation before displaying the next image frame. As such, the pixels of the display panel can be timely and accurately compensated without being noticed by the user when displaying images corresponding to the display content. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed embodiments without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the disclosure covers modifications and variations provided that they fall within the scope of the following claims and their equivalents.