Display device for compensating degradation and compensation method thereof

Abstract

A display device for compensating for degradation and a compensation method thereof are disclosed. The display device according to the present invention comprises: a display panel including a plurality of sub-pixels for displaying an image; a memory configured to store a lookup table including gain values; and a degradation compensation unit configured to compensate for degradation of degraded sub-pixels based on a sensing voltage input from the display panel and update the lookup table by measuring the brightness of an image displayed on the display panel.

Description

Technical Field

[0001] The present invention relates to a display device and a degradation compensation method. Background Art

[0002] With the development of multimedia, the demand for flat panel displays is increasing. As a result, flat panel display devices such as liquid crystal display devices, plasma display devices, and organic light emitting display devices have been commercialized. Among these flat panel display devices, organic light emitting display devices are currently widely used due to their high response speed, high brightness, and excellent viewing angle.

[0003] However, the brightness characteristics of the organic light emitting display panel may deteriorate due to degradation of the organic light emitting device after a certain period of time. As the driving time increases, the degradation rate of the organic light emitting diode may increase, and the brightness characteristics may deteriorate rapidly. Summary of the invention

[0004] An object of the present invention is to provide a display device capable of compensating for degradation and a method for compensating for the degradation thereof.

[0005] Another object of the present invention is to provide a display device and a compensation method thereof capable of improving image compensation efficiency by measuring the brightness of an actual image and updating a lookup table.

[0006] To achieve these objectives and other features, a display device according to an example of the present invention may include: a display panel including a plurality of sub-pixels for displaying an image; a memory configured to store a lookup table including gain values; and a degradation compensation unit configured to compensate for degradation of degraded sub-pixels based on a sensing voltage input from the display panel and to update the lookup table by measuring the brightness of an image displayed on the display panel.

[0007] The degradation compensation unit may include: a lookup table updating unit, which is configured to write a new lookup table by measuring the brightness of the image displayed on the display panel to update the lookup table stored in the memory; a gain value reading unit, which is configured to read the gain value of the lookup table stored in the memory; and a data modulation unit, which is configured to modulate data input to the display panel based on the gain value from the gain value reading unit.

[0008] The lookup table updating unit may include: a brightness measuring unit, which is configured to measure the brightness of an image displayed on the display panel; a gain value calculating unit, which is configured to calculate the gain value based on the brightness measured in the brightness measuring unit; and a lookup table writing unit, which is configured to write the new lookup table based on the gain value calculated in the gain value calculating unit.

[0009] The brightness of the image displayed on the display panel may be measured by a camera. The camera may be a charge coupled device camera.

[0010] The brightness measurement unit may measure the brightness of the degraded region of the display panel and the brightness of a reference brightness measurement region of the display panel. The reference brightness measurement region may be a surrounding region of the degraded region. The distance between the reference brightness measurement region and the degraded region may be equal to the sum of the widths of 15 to 20 sub-pixels.

[0011] The gain value calculation unit may calculate the gain value based on the brightness of the degradation area of ​​the display panel and the reference brightness of the reference brightness measurement area. At this time, the reference brightness of the reference brightness measurement area may be an average value of brightness of a plurality of positions of the reference brightness measurement area.

[0012] The lookup table writing unit may write the new lookup table by calculating gain values ​​of a plurality of degradation regions.

[0013] According to an example of the present invention, a method for compensating for degradation of a display device may include: measuring the brightness of an image displayed on a display panel of the display device; calculating a gain value based on the measured brightness; writing a lookup table based on the calculated gain value and updating a previous lookup table using the lookup table to which the write operation was performed; modulating data according to the updated lookup table; and applying the modulated data to the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic block diagram according to an embodiment of the present invention.

[0015] Figure 2 is a schematic block diagram of a sub-pixel of an organic light emitting display device according to an embodiment of the present invention.

[0016] Figure 3 is a circuit diagram of a sub-pixel of an organic light emitting display device according to an embodiment of the present invention.

[0017] Figure 4 is a block diagram illustrating a detailed structure of a degradation compensation unit of an organic light emitting display device according to an embodiment of the present invention.

[0018] Figure 5 is a block diagram illustrating a structure of a lookup table updating unit of an organic light emitting display device according to an embodiment of the present invention.

[0019] Figure 6 2 is a diagram showing a lookup table before updating and a lookup table after updating according to an embodiment of the present invention.

[0020] Fig. 7A and 7B 1 and 10 are views conceptually showing brightness compensation by a lookup table before updating and brightness compensation by a lookup table after updating, respectively.

[0021] Figure 8 is a flowchart illustrating a method of driving an organic light emitting display device according to an embodiment of the present invention.

[0022] Fig. 9 is a diagram illustrating an image of a display panel captured by a camera according to an embodiment of the present invention.

[0023] Fig.10 is a diagram illustrating luminance measurement results in a degraded area and a reference luminance measurement area obtained by a camera.

[0024] Fig.11 is a view showing calculation of a gain value according to the luminance of a degraded area and the luminance of a reference luminance measurement area.

[0025] Fig.12 1 is a view showing a lookup table that is newly written (ie, a write operation is newly performed) and updated in the organic light emitting display device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0026] The advantages and features of the present invention and the methods for achieving these advantages and features will become clear through the embodiments described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided to make the disclosure of the present invention sufficient and complete to help those skilled in the art to fully understand the scope of the present invention, which is limited only by the scope of the appended claims.

[0027] The shapes, sizes, proportions, angles, quantities, etc. disclosed in the accompanying drawings for describing the embodiments of the present invention are exemplary, and therefore, the present invention is not limited to the details shown in the drawings. The same reference numerals represent the same components throughout the application. In addition, in the following description of the present invention, when a detailed description of a known related art is determined to unnecessarily obscure the focus of the present invention, its detailed description may be omitted herein. In the case of using the terms "including", "having" and "comprising" mentioned in this specification, other components may be added unless the term "only" is used.

[0028] When analyzing components, they should be interpreted as including a margin of error even if not explicitly stated.

[0029] When describing a positional relationship, for example, when the positional relationship between two parts is described as "on", "above", "below", "after", etc., one or more other parts may be set between the two parts, unless "immediately" or "directly" is used.

[0030] When describing a time relationship, for example, when the time sequence is described as "after", "subsequently", "next", "before", etc., discontinuous situations may also be included unless "immediately" or "directly" is used.

[0031] Although the terms "first", "second", etc. are used to describe various components, these components are not substantially limited by these terms. These terms are merely used to distinguish one component from other components. Therefore, within the scope of the technical spirit of the present invention, the first component described below may also be substantially the second component.

[0032] When describing components in the specification, terms such as "first", "second", "A", "B", "(a)", and "(b)" may be used. These terms are only used to distinguish one component from other components, and the nature, sequence, order, or number of the corresponding components are not limited by these terms. When a component is described as being "connected to" or "joined to" another component, it may not only be directly connected or in contact with the other component, but it should also be understood that other components may be inserted therebetween, or other components may be connected, joined, or in contact therebetween.

[0033] In the specification, "display device" may include display devices in a narrow sense, such as a liquid crystal module (LCM), an OLED module, and a quantum dot (QD) module including a display panel and a driver driving the display panel. In addition, the display device may also include: laptop computers, televisions, and computer monitors as finished products or final products including LCMs, OLED modules, and QD modules; device displays including car displays or other types of vehicles; and set electronic devices, set devices, or set equipment such as mobile electronic devices (such as smart phones or electronic tablets).

[0034] Therefore, the display device in the specification may include: a display device in a narrow sense, such as an LCM, an OLED module, a QD module, etc.; and an application product or a unit device that is an end consumer device including an LCM, an OLED module, a QD module, etc.

[0035] In addition, in some cases, they may be separately expressed: an LCM, an OLED module, and a QD module including a display panel and a driver may be expressed as a "display device" in some cases, and an electronic device as a finished product including the LCM, OLED module, or QD module may be expressed as a "unit device." For example, a display device in a narrow sense may be a concept including a display panel such as a liquid crystal display (LCD) panel, an OLED panel, or a QD display panel, and a source printed circuit board (PCB) as a controller for driving the display panel, and a unit device may be a concept further including a unit PCB as a unit controller electrically connected to the source PCB to control the entire unit device.

[0036] The display panel used in the embodiments of the present invention may be a display panel of all types, such as a liquid crystal display panel, an OLED panel, a QD display panel, an electroluminescent display panel, etc. However, the present invention is not limited to a specific display panel, such as a display panel whose frame can be bent using the flexible substrate of the OLED panel of the embodiments of the present invention and the backplane support structure under the flexible substrate. In addition, the display panel used in the display device according to the embodiments of the present invention does not limit the shape or size of the display panel.

[0037] For example, when the display panel is an OLED panel, the display panel may include a plurality of gate lines, a plurality of data lines, and a plurality of pixels formed in the intersection area of ​​the gate lines and the data lines. In addition, each pixel may include: an array of thin film transistors (TFTs) as elements for selectively applying voltage to each pixel; an OLED layer on the array; and an encapsulation substrate or an encapsulation layer disposed on the array to cover the OLED layer. The encapsulation layer may protect the TFT and OLED layers from external impacts and prevent moisture or oxygen from penetrating into the OLED layer. In addition, the layer formed on the array may include an inorganic light-emitting layer, such as a nano-sized material layer or a quantum dot.

[0038] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. All components of each display device according to all embodiments of the present invention are operably connected and configured.

[0039] Figure 1 is a schematic block diagram according to the present invention. Figure 2 is a schematic block diagram of a sub-pixel of an organic light emitting display device according to an embodiment of the present invention.

[0040] like Figure 1 As shown, the organic light emitting display device 1 includes an image processing unit 110, a degradation compensation unit 150, a memory 160, a timing control unit 120, a gate driving unit 130, a data driving unit 140, a power supply unit 180, and a display panel PAN including a plurality of sub-pixels SP.

[0041] The image processing unit 110 outputs image data provided from the outside and driving signals for driving various devices. For example, the driving signals from the image processing unit 110 may include a data enable signal, a vertical synchronization signal, a horizontal synchronization signal, and a clock signal.

[0042] The sensing voltage Vsen is provided from the data driving unit 140 to the degradation compensation unit 150. The degradation compensation unit 150 modulates the input image data Idata of each sub-pixel SP of the current frame based on the gain value of the lookup table stored in the memory 160, and then provides the modulated image data Mdata to the timing control unit 120. In addition, the degradation compensation unit 150 performs a write operation on the lookup table LUT (or writes to the lookup table LUT), and provides the written lookup table LUT to the memory 160 to update the lookup table of the memory 160.

[0043] The modulated image data Mdata and the driving signal modulated by the degradation compensation unit 150 are provided to the timing control unit 120. The timing control unit 120 writes and outputs a gate timing control signal GDC for controlling the driving timing of the gate driving unit 130 and a data timing control signal DDC for controlling the driving timing of the data driving unit 140 based on the driving signal from the image processing unit 110.

[0044] The timing control unit 120 controls driving timings of the gate driving unit 130 and the data driving unit 140 to obtain at least one sensing voltage Vsen from each sub-pixel SP and provides the obtained sensing voltage Vsen to the degradation compensation unit 150 .

[0045] The gate driving unit 130 outputs a scan signal to the display panel PAN in response to the gate timing control signal GDC provided from the timing control unit 120. The gate driving unit 130 outputs the scan signal through a plurality of gate lines GL1 to GLm, where m may be a positive number such as a positive integer. In this case, the gate driving unit 130 may be formed in the form of an integrated circuit (IC) and may be formed in the display panel by directly depositing various patterns and layers, but is not limited thereto.

[0046] The data driving unit 140 outputs a data voltage to the display panel PAN in response to a data timing control signal DDC input from the timing control unit 120. The data driving unit 140 samples and latches a digital data signal DATA provided from the timing control unit 120 and converts it into an analog data voltage based on a gamma voltage. The data driving unit 140 outputs the data voltage through a plurality of data lines DL1 to DLn, where n may be a positive number such as a positive integer.

[0047] In addition, the data driving unit 140 provides the sensing voltage Vsen input from the display panel PAN to the degradation compensation unit 150 through the sensing voltage readout line.

[0048] In this case, the data driving unit 140 may be mounted on the top surface of the display panel PAN in the form of an integrated circuit (IC), or may be formed by directly stacking various patterns and layers on the display panel PAN, but is not limited thereto.

[0049] The power supply unit 180 outputs a high potential driving voltage EVDD and a low potential driving voltage EVSS, etc., and provides them to the display panel PAN. The high potential driving voltage EVDD and the low potential driving voltage EVSS are provided to the display panel PAN through the power line. At this time, the voltage from the power supply unit 180 is applied to the data driving unit 140 or the gate driving unit 130 to drive them.

[0050] The display panel PAN displays an image based on the data signal and the scan signal from the data driving unit 140 and the gate driving unit 130 and the power from the power supply unit 180 .

[0051] The display panel includes a plurality of sub-pixels SP for displaying an image. The sub-pixels SP may include red sub-pixels, green sub-pixels, and blue sub-pixels. In addition, the sub-pixels SP may include white sub-pixels, red sub-pixels, green sub-pixels, and blue sub-pixels. The white sub-pixels, red sub-pixels, green sub-pixels, and blue sub-pixels may be formed in the same region or may be formed in different regions.

[0052] The lookup table of degradation compensation gain values ​​is stored in the memory 160. In addition, the update timing of the lookup table is also stored in the memory, and this update timing is notified to the user through the display panel. For example, the update timing can be determined by the number of driving times or the driving time. That is, as long as the set number of driving times and the driving time are satisfied, the lookup table LUT can be repeatedly updated.

[0053] The update cycle of the lookup table LUT may be always the same or may be changed. The degradation of the organic light-emitting layer of the organic light-emitting device may be accelerated as the number of driving times or driving time passes. Therefore, as the number of driving times or driving time passes, the lookup table LUT may be updated in a shorter cycle rather than the same cycle.

[0054] Furthermore, the lookup table LUT may be periodically updated.

[0055] For example, when the organic light emitting display device 1 is installed in a vehicle such as a car, the update cycle of the lookup table LUT is when the user visits a car repair shop to check or repair his car. In addition, in the case where the organic light emitting display device 1 is adapted for use in an electronic mobile device such as a smart phone or a tablet PC, the update cycle of the lookup table LUT is when the user visits a mobile device dealer or a repair shop.

[0056] The lookup table LUT stored in the memory 160 is formed in various types. For example, the lookup table LUT may be formed as a table type of gain values ​​corresponding to the sensing voltage Vsen and may be stored in the form of a first order function or a second order function of the sensing voltage Vsen and the gain value.

[0057] like Figure 2 As shown, one subpixel SP may be connected to a gate line GL1, a data line DL1, a sensing voltage readout line SRL1, and a power line PL1. The number of transistors and capacitors and a driving method of the subpixel SP (or each subpixel SP) are determined according to a circuit configuration.

[0058] Figure 3is a circuit diagram illustrating each sub-pixel SP of the organic light emitting display device 1 according to an embodiment of the present invention.

[0059] like Figure 3 As shown, the organic light emitting display device 1 according to the present invention includes a gate line GL, a data line DL, a power line PL, and a sensing line SL that cross each other to define a sub-pixel SP. A driving TFT DT, an organic light emitting device D, a storage capacitor Cst, a first switch TFT ST1, and a second switch TFT ST2 are disposed in the sub-pixel SP.

[0060] The organic light emitting device D includes an anode connected to the second node N2, a cathode connected to an input terminal of a low potential driving voltage EVSS, and an organic light emitting layer disposed between the anode and the cathode.

[0061] The driving TFT DT controls the current Id flowing through the organic light emitting device D according to the gate-source voltage Vgs. The driving TFT DT includes a gate connected to the first node N1, a drain connected to the power line PL providing the high potential driving voltage EVDD; and a source connected to the second node N2.

[0062] The storage capacitor Cst is connected between the first node N1 and the second node N2.

[0063] When the display panel PAN is in operation, the first switch TFT ST1 applies the data voltage Vdata charged in the data line DL to the first node N1 in response to the gate signal (or scan signal) SCAN to turn on the driving TFT DT. In this case, the first switch TFT ST1 includes a gate electrode connected to the gate line GL to receive the scan signal SCAN, a drain electrode connected to the data line DL to receive the data voltage Vdata, and a source electrode connected to the first node N1.

[0064] The second switch TFT ST2 switches a current between the second node N2 and the sensing voltage readout line SRL in response to the sensing signal SEN to store the source voltage of the second node N2 in the sensing capacitor Cx of the sensing voltage readout line SRL. The second switch TFT ST2 switches a current between the second node N2 and the sensing voltage readout line SRL in response to the sensing signal SEN when the display panel PAN operates to reset the source voltage of the driving TFT DT to the initialization voltage Vpre. In this case, the gate of the second switch TFT ST2 is connected to the sensing line SL, the drain is connected to the second node N2, and the source is connected to the sensing voltage readout line SRL.

[0065] In the organic light-emitting display device 1 having such a structure, the organic light-emitting layer degrades as the driving time increases, the brightness decreases, and due to such degradation, an irreparable afterimage appears as the use time of the organic light-emitting device increases. In order to solve the brightness degradation and afterimage, it is necessary to increase the brightness to the target brightness by compensating for the degradation of the organic light-emitting layer.

[0066] According to an example of the present invention, the gain value of the sensing voltage Vsen input from the display panel PAN is stored as a lookup table LUT to compensate for degradation. Specifically, according to an example of the present invention, the degradation is compensated by updating the lookup table LUT at a set timing or a necessary time. The reason is as follows.

[0067] The lookup table LUT is made by measuring the brightness and initial sensing voltage Vsen of the display panel PAN of the organic light-emitting display device 1 before shipment. That is, before the product is shipped, the sensing voltage Vsen based on the brightness drop due to degradation occurring in the display panel PAN is measured, and the sensing voltage Vsen is made into the lookup table LUT and stored in the memory 160.

[0068] The lookup table LUT is used to compensate for degradation when a user actually uses the organic light-emitting display device 1 after the product is shipped. That is, the sensing voltage Vsen is continuously measured while the organic light-emitting display device 1 is used. The degradation compensation unit 150 reads a gain value corresponding to the measured sensing voltage Vsen from the lookup table LUT, then modulates the image data by the read gain value, and provides the modulated image data to the display panel PAN.

[0069] Therefore, increased current is supplied to a sub-pixel or region whose brightness may be reduced due to degradation (this region is composed of multiple sub-pixels, and the sub-pixel or region that has not been degraded will be referred to as a region hereinafter) to almost equally convert the reduced brightness of this region into the brightness of the non-degraded region.

[0070] However, the relationship between the gain value and the sensing voltage Vsen of the lookup table LUT made before the product leaves the factory is different from the relationship between the gain value and the sensing voltage Vsen when the organic light emitting display device 1 is actually used. This difference may lead to a reduction in the degradation compensation efficiency when the organic light emitting display device 1 is actually used, so that there may be risks in accurate compensation, thereby deteriorating the image quality of the organic light emitting display device 1.

[0071] There are various reasons for the difference between the gain value of the lookup table LUT made before shipment and the gain value of the product actually used. That is, the environment in which the lookup table LUT is made before the product is shipped may be different from the environment in which the organic light emitting display device 1 is actually used. For example, when the organic light emitting display device 1 is applied to a vehicle, the vehicle may be used in harsh environments such as high and low temperatures.

[0072] Therefore, the manufacturing environment of the lookup table LUT implemented in the factory is greatly different from the environment in which the organic light emitting display device 1 is actually used. Due to this difference, it may be difficult to use the lookup table LUT manufactured in the factory to accurately compensate for the degradation of the organic light emitting display device 1 used in a harsh environment.

[0073] In addition, since degradation may accumulate as the organic light emitting display device 1 is used for a long time, there may be a difference between the gain value of the lookup table LUT made before the product is shipped and the gain value of the lookup table LUT of the organic light emitting display device 1 in which degradation has accumulated. The increased current is supplied to the degradation compensation region, and the degradation of this region is accelerated by the increase in current, so that it may be difficult to accurately compensate for degradation of the organic light emitting display device in which degradation has accumulated for a long time.

[0074] In the embodiment of the present invention, since the lookup table LUT is rewritten at a set time or as needed to update the lookup table LUT stored in the memory, inaccurate degradation compensation caused by differences in usage environments or long-term accumulation of degradation can be prevented. This will be described in detail below with reference to the accompanying drawings.

[0075] Figure 4 is a block diagram showing the structure of the degradation compensation unit 150 according to an embodiment of the present invention.

[0076] like Figure 4 As shown, the degradation compensation unit 150 includes a lookup table updating unit 152 , a gain value reading unit 154 and a data modulation unit 156 .

[0077] The lookup table updating unit 152 updates the lookup table LUT stored in the memory 160 by performing a write operation on the lookup table LUT at a set update time or as needed. The lookup table updating unit 152 directly captures images in the degraded area and the non-degraded area of ​​the display panel PAN to directly measure the brightness in these areas, and then calculates the gain value according to the brightness difference between these areas. The lookup table updating unit 152 updates the lookup table LUT by performing a new write operation on the lookup table LUT (or newly writing the lookup table LUT) based on the calculated gain value and storing the lookup table LUT in the memory 160.

[0078] Since a brightness measurement camera should be provided to measure the brightness of the display panel PAN, the lookup table LUT should be updated at a specific location. For example, in the case where the organic light-emitting display device 1 is installed in a car, the lookup table is updated in a car repair shop or a car dealer store having a brightness measurement camera. In addition, in the case where the organic light-emitting display device 1 is adapted for use in an electronic mobile device such as a smartphone or a tablet PC, the lookup table is updated in a repair shop or a dealer store having a brightness measurement camera. However, without being limited to these locations, the lookup table LUT may be updated at various other locations.

[0079] The sensing voltage Vsen of the display panel PAN is input to the gain value reading unit 154 from the data driving unit 140 , and a gain value corresponding to the sensing voltage Vsen is read from the lookup table LUT stored in the memory 160 to provide the read gain value to the data modulation unit 154 .

[0080] The input image data Idata of each sub-pixel of the current frame is modulated by the data modulation unit 156 based on the gain value provided from the gain value reading unit 154 , and then the modulated image data Mdata is provided to the timing control unit 120 .

[0081] A lookup table LUT including gain values ​​is stored in the memory 160 .

[0082] The lookup table LUT according to the present invention may be in a first order function form or a second order function form with respect to the sensing voltage Vsen and the gain value G. In addition, the lookup table LUT may be a table in which the sensing voltage Vsen and the gain value G correspond to each other.

[0083] The update time of the lookup table LUT may be stored in the memory 160. The memory 160 provides the update time of the lookup table LUT according to the request of the degradation compensation unit 150, and the degradation compensation unit 150 may display the update time of the lookup table LUT on the display panel PAN through the timing control unit 120 to notify the user of the update time.

[0084] Figure 5 It is shown Figure 4 Block diagram of the lookup table update unit 152.

[0085] like Figure 5 As shown, the lookup table updating unit 152 includes a brightness measuring unit 157 , a gain value calculating unit 158 ​​and a lookup table writing unit 159 .

[0086] The brightness measurement unit 157 measures the brightness of the photographed area based on the image of the display panel PAN input from the camera. At this time, the camera takes a picture of not only the degraded area but also the non-degraded area, and the brightness measurement unit 157 measures the brightness of the degraded area and the non-degraded area.

[0087] The position of the degraded area of ​​the display panel PAN can be detected by measuring the sensing voltage Vsen of the corresponding area. The degradation compensation unit 150 detects the position of the degraded area and the non-degraded area by sensing the voltage Vsen and provides it to the camera. The camera takes photos of the degraded area and the non-degraded area based on the provided information. In this case, the camera can take photos of multiple sub-pixels and areas.

[0088] The brightness measurement result of the brightness measurement unit 157 is input to the gain value calculation unit 158 ​​to calculate the gain value. At this time, the gain value calculation unit 158 ​​compares the brightness of the degraded area with the brightness of the non-degraded area to calculate the gain value.

[0089] The lookup table writing unit 159 writes the lookup table LUT by the calculated gain value, and then provides the written new lookup table LUT to the memory to update the lookup table LUT stored in the memory 160 .

[0090] The lookup table writing unit 159 writes the relationship between the sensing voltage Vsen and the gain value as a table based on the gain values ​​of multiple locations and provides it to the memory 160 , or writes the relationship between the sensing voltage Vsen and the gain value as a function and provides it to the memory 160 .

[0091] Figure 6 1 is a view showing a lookup table LUT stored in an organic light emitting display device 1 according to an example of the present invention, which shows a previous (before updating) lookup table LUT1 and an updated lookup table LUT2. In this case, the lookup tables LUT1 and LUT2 are functions representing the relationship between the gain value sensed by the display panel PAN and the sensing voltage Vsen, respectively.

[0092] Fig. 7A and 7B These are views conceptually showing brightness compensation performed by the lookup table LUT1 before updating and brightness compensation performed by the lookup table LUT2 after updating, respectively.

[0093] like Figure 6As shown, the lookup tables LUT1 and LUT2 are composed of straight lines in the form of linear functions (i.e., first-order functions). In this case, the straight line of the updated lookup table LUT2 has a larger slope than the straight line of the previous lookup table LUT1. The reason is that the current organic light-emitting display device 1 is used in a harsh environment or deteriorates for a long period of time, so more compensation is required than the first lookup table LUT1 prepared in the manufacturing factory when the organic light-emitting display device 1 is manufactured.

[0094] As a result of sensing the sensing voltage Vsen, degradation occurs in the first region X1 and the second region X2. In the lookup table LUT1 before updating, the gain value in the first region X1 is 1.032, and the gain value in the second region X2 is 1.066. On the other hand, in the updated lookup table LUT2, the gain value of the first region X1 is 1.052, and the gain value of the second region X2 is 1.111.

[0095] like Fig. 7A As shown, when the brightness of the non-degraded area is 100% and the brightness of the degraded first area X1 and the second area X2 is 95% and 90% respectively, the gain values ​​of the first area X1 and the second area X2 are G1=1.032 and G2=1.066 respectively. When the first area X1 and the second area X2 are compensated by these gain values ​​G1 and G2, the brightness of the first area X1 is about 98% (95%×1.032=98.04%), and the brightness of the second area X2 is about 96% (90%×1.066=95.94%).

[0096] Therefore, even if the brightness is compensated by the previous lookup table LUT1, the brightness of the degraded area does not become 100%, but becomes a brightness lower than 100%, so that thorough compensation cannot be achieved.

[0097] On the other hand, Figure 7B As shown, when the degraded brightness of the first region X1 and the second region X2 are 95% and 90% respectively, the gain values ​​of the first region X1 and the second region X2 are G1=1.052 and G2=1.111 respectively. When the first region X1 and the second region X2 are compensated by these gain values ​​G1 and G2, the brightness x1 of the first region X1 and the brightness x2 of the second region X2 are both about 100% (x1=95%×1.052=99.94%, x2=90%×1.111=99.99%).

[0098] As described above, the degradation compensation performed by the lookup table LUT1 before updating does not increase the brightness of the corresponding area to 100%, while the degradation compensation performed by the lookup table LUT2 after updating increases the brightness of the corresponding area to about 100%. Therefore, by capturing an image displayed on the current display panel PAN, measuring the brightness, and updating the lookup table LUT1 to the new lookup table LUT2, the degradation compensation efficiency of the degraded area of ​​the organic light emitting display device 1 can be greatly improved.

[0099] Figure 8 1 is a flowchart illustrating a method of driving an organic light emitting display device in which degradation is compensated according to an embodiment of the present invention. The method of driving the organic light emitting display device 1 will be described in detail with reference to the accompanying drawings.

[0100] like Figure 8 As shown, first, the organic light emitting display device 1 is driven to display an image on the display panel PAN (step S101 ).

[0101] Subsequently, it is determined whether it is the update time of the lookup table LUT (step S102). If it is not the update time, the display panel PAN is driven by compensating for the degradation using the lookup table LUT1 before the update (step S108).

[0102] At this time, the update time of the lookup table LUT may correspond to the number of driving times or driving time of the organic light emitting display device 1. In addition, the update time of the lookup table LUT may be the inspection time or repair time of a device having an organic light emitting display device such as a car or a mobile phone.

[0103] When the organic light-emitting display device 1 is in the update time of the lookup table LUT (step S102), a camera is set on the front side of the display panel PAN to take a photo of the image displayed on the display panel PAN, and inputs the taken image photo to the brightness measurement unit 157 of the lookup table update unit 152 (step S103).

[0104] Fig. 9 is a diagram illustrating an image of the display panel PAN captured by the camera 190 .

[0105] like Fig. 9 As shown, the camera 190 is set in front of the display image of the display panel PAN. Although not shown in the figure, the camera 190 can be installed on a transport means to take a picture of the screen while moving from the front side of the display panel PAN along the short side direction or the long side direction of the display panel PAN. In addition, the camera 190 can be moved along the front and rear direction of the display panel PAN. The position of the deteriorated area is input to the camera 190, so that the camera 190 can be moved to the corresponding position by the transport means.

[0106] The camera 190 may use a CCD (Charge Coupled Device) camera, but is not limited thereto.

[0107] like Fig.10 As shown, the camera 190 takes photos of the degradation regions X1 and X2 and photos of reference luminance measuring regions S1 and S2. The reference luminance measuring regions S1 and S2 are regions that are not degraded. The camera 190 measures the luminance of the images of the degradation regions X1 and X2 and the reference luminance measuring regions S1 and S2, and calculates a gain value in the lookup table update unit 152 based on the luminance of the degradation regions X1 and X2 and the luminance of the reference luminance measuring regions S1 and S2.

[0108] Specifically, according to an example of the present invention, the surroundings of the degradation areas X1 and X2 are set as reference luminance measurement areas S1 and S2, thereby calculating the gain value based on the luminance of the degradation areas X1 and X2 and the luminance of the surrounding reference luminance measurement areas S1 and S2 (ie, reference luminance).

[0109] Therefore, when calculating the gain values ​​of the plurality of degradation regions X1 and X2, the luminance of the degradation regions X1 and X2 and the luminance of the corresponding reference luminance measurement regions S1 and S2 are measured, and the corresponding degradation occurrence regions are measured respectively to calculate the gain value of each of the degradation regions X1 and X2. For example, the gain value G1 of the first degradation region X1 is calculated by the luminance of the first degradation region X1 and the luminance of the first reference luminance measurement region S1, and the gain value G2 of the second degradation region X2 is calculated by the luminance of the second degradation region X2 and the luminance of the second reference luminance measurement region S2.

[0110] In this case, the distance d between the degradation areas X1, X2 and the reference brightness measurement areas S1, S2 is approximately equal to the sum of the widths of 15-20 sub-pixels. However, this distance is not limited thereto and may be variously set.

[0111] As described above, according to the example of the present invention, the reasons why the reference luminance measurement areas S1 and S2 are set as the surrounding areas of the degradation areas X1 and X2, respectively, are as follows.

[0112] The degradation of the organic light emitting layer may occur on the entire screen of the entire display panel PAN, but may mainly occur in a certain area. In particular, the degradation of the organic light emitting layer significantly occurs in an area where an image of constant brightness is displayed for a long time. For example, severe degradation occurs in an area where the same character or picture is displayed for a long time.

[0113] The degradation regions X1 and X2 include a plurality of sub-pixels, and the sub-pixels of the degradation regions X1 and X2 may not all have the same brightness but may have different brightnesses. In addition, the brightness around the degradation regions X1 and X2 may also be affected by the degradation regions X1 and X2.

[0114] For example, in the case of displaying an image having a specific shape, the brightness must be gradually changed from the boundary of the area where the image is displayed to the above-mentioned certain area to smoothly display the image. In addition, since the current of the same magnitude is supplied to the area where the same character or picture is displayed for a long time, not only the corresponding area but also the adjacent area can be affected by the long-term supply of the same current.

[0115] Although the adjacent regions affected by these degraded regions X1 and X2 are not sensed as degraded regions, their brightness may be slightly reduced compared to other regions (eg, regions not affected by the degraded regions X1 and X2 ).

[0116] Therefore, if other areas except the surrounding areas of the degraded areas X1 and X2 are set as reference brightness measurement areas to calculate the gain value, even if the degraded areas X1 and X2 are compensated by the calculated gain value, a brightness difference will occur between the degraded areas X1, X2 after the degradation compensation and their surrounding areas. In other words, a brightness difference will occur between the degraded areas X1, X2 whose degradation is compensated and an area whose brightness is slightly reduced due to the influence of the degradation.

[0117] Although such a brightness difference is very small, since the brightness changes sharply at the boundary between the degradation areas X1 and X2 , the user's eyes can clearly recognize the subtle brightness difference.

[0118] According to an example of the present invention, since peripheral regions of the degradation regions X1 and X2 are set as reference luminance measurement regions S1 and S2 , there is no luminance difference between the degradation regions X1 and X2 where degradation is compensated and the reference luminance measurement regions S1 and S2 .

[0119] In particular, in the present invention, since the distance d between the degraded regions X1, X2 and the reference brightness measurement regions S1, S2 is equal to the sum of the widths of 15-20 sub-pixels, there is no brightness difference between the degraded regions X1, X2 whose degradation is compensated and the surrounding regions of the degraded regions X1, X2. In addition, there is no brightness difference between the degraded regions X1, X2 whose degradation is compensated and other regions where degradation has not occurred.

[0120] If the distance d between the degraded regions X1, X2 and the reference brightness measurement regions S1, S2 is less than the sum of the widths of 15-20 sub-pixels, the brightness of the reference brightness measurement regions S1, S2 is significantly reduced compared to the brightness of other regions that are not degraded (i.e., 100% brightness). Therefore, in the case where the degraded regions X1, X2 are compensated by the gain values ​​calculated based on the reference brightness measurement regions S1, S2, the user recognizes the brightness difference between the degraded regions X1, X2 where the degradation is compensated and the non-degraded regions.

[0121] If the distance d between the degradation region X1, X2 and the reference brightness measurement region S1, S2 is greater than the sum of the widths of 15-20 sub-pixels, the user may recognize the brightness difference between the degradation compensated degradation region X1, X2 and the surrounding region of the degradation region X1, X2.

[0122] Each of the reference luminance measurement areas S1, S2 may be photographed a plurality of times. Since luminance around the degradation areas X1 and X2 has a slight difference depending on a position, a spot may occur at a boundary due to a luminance difference depending on a degradation compensation position.

[0123] According to an example of the present invention, by photographing a plurality of positions of each of the reference brightness measurement areas S1, S2 and determining the average value of the brightness of the plurality of photographed positions as the reference brightness, the brightness difference depending on the position can be minimized. For example, in the present invention, 8 points of each of the reference brightness measurement areas S1, S2 can be photographed, and the average brightness value thereof can be determined as the reference brightness. However, the present invention is not limited thereto, and the average brightness value can be determined as the reference brightness by photographing the positions of 7 points or less or 9 points or more.

[0124] Return to reference Figure 8 , the brightness measuring unit 157 of the lookup table updating unit 152 analyzes the captured image input from the camera 190 to measure the brightness of the corresponding area (step S104), and the gain value calculating unit 158 ​​calculates the gain value based on the measured brightness (step S105).

[0125] Fig.11 is a view showing calculation of a gain value according to the luminance of the degradation regions X1 and X2 and the luminance of the reference luminance measurement regions S1 and S2.

[0126] like Fig.11 As shown, the measured brightness of the first degradation region X1 is 95%, and the measured brightness of the first reference brightness measurement region S1 is 100%. Therefore, in order to increase the brightness of the first degradation region X1 (95%) to the brightness of the first reference brightness measurement region S1 (100%), the gain value G1 should be set to G1=100 / 95=1.052.

[0127] In addition, the measured brightness of the second degradation area X2 is 90%, and the measured brightness of the second reference brightness measurement area S2 is 100%. Therefore, in order to increase the brightness of the second degradation area X2 (90%) to the brightness of the second reference brightness measurement area S2 (100%), the gain value G2 should be set to G2=100 / 90=1.111.

[0128] Return to reference Figure 8 , after the gain value is calculated and written into the new lookup table LUT (step S106 ), the lookup table LUT stored in the memory 160 is updated by the new lookup table LUT (step S107 ).

[0129] Fig.12 is a view showing a lookup table LUT that is newly written and updated in the organic light emitting display device 1 according to an example of the present invention.

[0130] like Fig.12 As shown, a function of the sense voltage Vsen measured in the degradation region with respect to the gain value corresponding to the sense voltage Vsen can be written as a lookup table LUT. In this case, the x-axis (horizontal axis) is the sense voltage Vsen, and the y-axis (vertical axis) is the gain value.

[0131] At this time, since the gain value of the sensing voltage Vsen measured in the first degradation area X1 is 1.052, and the gain value G2 of the sensing voltage Vsen measured in the second degradation area X2 is 1.111, the lookup table LUT of the linear form of the first-order function can be written by connecting these coordinates (i.e., a write operation is performed on the lookup table LUT).

[0132] In addition, according to an example of the present invention, a lookup table LUT can be formed by measuring the brightness of three or more degradation areas and the brightness of the reference brightness measurement area of ​​the surrounding area to calculate three or more gain values. In this case, the lookup table LUT can be in the form of a linear function connecting the coordinates of the gain value G relative to the three or more sensing voltages Vsen, or in the form of a curve of a second-order function.

[0133] Refer again Figure 8 , the organic light emitting display device 1 is driven by compensating the degradation using the updated lookup table LUT (step S108). That is, after the gain value reading unit 154 of the degradation compensation unit 150 reads the gain value of the lookup table LUT stored in the memory, the data modulation unit 156 modulates the image data Idata by the gain value to provide the modulated image data Mdata to the display panel PAN for displaying an image.

[0134] As described above, according to an example of the present invention, an image displayed on the organic light emitting display device 1 is directly photographed at an update time or a required time to measure the brightness of the image, and then the lookup table is updated to compensate for the degradation of the organic light emitting display device. Therefore, even if the organic light emitting display device 1 is used in a harsh environment or when degradation accumulates for a long time, the degradation can be accurately compensated.

[0135] The features, structures, effects, etc. described in the above examples of the present application are included in at least one example of the present application and are not necessarily limited to only one example. In addition, the features, structures, effects, etc. described in at least one example of the present application can be combined or modified with respect to other examples by a person of ordinary skill in the art to which the present application belongs. Therefore, the contents related to these combinations and modifications should also be interpreted as being included in the scope of the present application.

[0136] The present application is not limited to the above-mentioned embodiments and drawings. It will be obvious to a technician with common knowledge in the technical field to which the present application belongs that various substitutions, modifications and changes can be made without departing from the technical spirit of the present invention. Therefore, the scope of the present application is defined by the attached claims, and all changes and modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as included in the scope of the present application.

Claims

1. A display device, comprising: A display panel, the display panel comprising a plurality of sub-pixels for displaying an image; a memory configured to store a lookup table including gain values; as well as a degradation compensation unit configured to compensate for degradation of a degraded sub-pixel based on a sensing voltage input from the display panel, The degradation compensation unit is further configured to update a previous lookup table stored in the memory by measuring the brightness of an image displayed on the display panel during actual use of the display device after the device leaves the factory, wherein the previous lookup table includes a lookup table prepared before the display device leaves the factory, wherein the degradation compensation unit is configured to measure the brightness of the degraded area of ​​the display panel and the brightness of a reference brightness measurement area of ​​the display panel where no degradation has occurred, compare the brightness of the degraded area with the brightness of the reference brightness measurement area, and calculate a gain value for compensating the sub-pixels in the degraded area based on a ratio of the brightness of the degraded area to the brightness of the reference brightness measurement area, and The reference luminance measurement region is a surrounding region of the deteriorated region.

2. The display device according to claim 1, wherein the degradation compensation unit comprises: a lookup table updating unit configured to write a new lookup table by measuring the brightness of an image displayed on the display panel to update the lookup table stored in the memory; a gain value reading unit, the gain value reading unit being configured to read a gain value of a lookup table stored in the memory; as well as A data modulation unit is configured to modulate data input to the display panel based on the gain value from the gain value reading unit.

3. The display device according to claim 2, wherein the lookup table updating unit comprises: a brightness measuring unit configured to measure the brightness of an image displayed on the display panel; a gain value calculation unit configured to calculate the gain value based on the brightness measured in the brightness measurement unit; as well as A lookup table writing unit is configured to write the new lookup table based on the gain value calculated in the gain value calculating unit. The display device according to claim 3 , wherein the brightness of the image displayed on the display panel is measured by a camera. The display device of claim 4 , wherein the camera comprises a charge coupled device camera. 6 . The display device according to claim 3 , wherein the luminance measuring unit measures the luminance of the degraded region and the luminance of the reference luminance measurement region. 7 . The display device according to claim 6 , wherein a distance between the reference luminance measurement region and the degraded region is equal to a sum of widths of 15 to 20 sub-pixels. The display device according to claim 6 , wherein the gain value calculation unit calculates the gain value. 9 . The display device according to claim 8 , wherein the reference brightness of the reference brightness measurement area is an average value of brightnesses of a plurality of positions of the reference brightness measurement area. 10 . The display device according to claim 3 , wherein the lookup table writing unit writes the new lookup table by calculating gain values ​​of a plurality of degradation regions.

11. A method for compensating for degradation of a display device, the method comprising: measuring the brightness of an image displayed on a display panel of the display device during actual use of the display device after shipment; Calculating a gain value based on the measured brightness; writing a lookup table based on the calculated gain value and using the written lookup table to update a previous lookup table during the actual use after the display device is shipped, the previous lookup table including a lookup table made before the display device is shipped; modulating the data according to the updated lookup table; as well as applying the modulated data to the display panel, The calculated gain values ​​include: The brightness of the degraded area of ​​the display panel and the brightness of the reference brightness measurement area where no degradation has occurred are measured by a camera. comparing the brightness of the degraded area with the brightness of the reference brightness measurement area to calculate the gain value for compensating the sub-pixels in the degraded area based on a ratio of the brightness of the degraded area to the brightness of the reference brightness measurement area, The reference luminance measurement region is a surrounding region of the deteriorated region.

12. The method of claim 11, wherein measuring brightness comprises: A photo of the image is taken by the camera.

13. The method of claim 11, wherein updating the lookup table comprises: The previous lookup table is updated based on the gains of the plurality of degraded regions.

Images