Display device

Abstract

The display device includes: a plurality of pixels connected to a plurality of scan lines, a plurality of control lines, a plurality of data lines, and a plurality of sensing lines; a scan driving unit that supplies scan signals to the plurality of scan lines and control signals to the plurality of control lines; a data driving unit that supplies one of an image data signal and a sensing data signal to the plurality of data lines; and a sensing unit that includes an analog-to-digital converter that converts sensing values ​​supplied through the plurality of sensing lines into a digital current code, and corrects the current code based on the conversion characteristics of the analog-to-digital converter, and senses the characteristics of the driving transistor based on the corrected current code.

Description

Technical Field

[0001] This invention relates to a display device and a driving method thereof, and more specifically, to a display device and a driving method thereof employing an external compensation method. Background Technology

[0002] Self-emissive display devices use multiple pixels connected to multiple scan lines and multiple data lines to display images. Each pixel has a light-emitting element and a driving transistor.

[0003] The driving transistor controls the amount of current supplied to the light-emitting element in accordance with the data signal supplied from the data line. The light-emitting element generates light of a predetermined brightness in accordance with the amount of current supplied from the driving transistor.

[0004] In order for a display device to display an image with uniform quality, the driving transistors included in each pixel should supply a uniform current to the light-emitting element in accordance with the data signal. However, the driving transistors included in each pixel have inherent characteristic values ​​that may be skewed.

[0005] As an example, the threshold voltage and mobility of the driving transistor may be set differently in each pixel or may change due to degradation caused by use, which may result in brightness deviations in the image. Summary of the Invention

[0006] One object of the present invention is to provide a display device that reflects the grayscale transformation characteristics of an analog-to-digital converter used in external compensation to correct sensing data.

[0007] Another object of the present invention is to provide a driving method for the display device.

[0008] However, the purpose of this invention is not limited to the above-described purpose, and various extensions can be made without departing from the spirit and scope of this invention.

[0009] To achieve an objective of the present invention, the display device according to various embodiments of the present invention can be driven by dividing a display period for displaying an image and a sensing period for sensing the characteristics of driving transistors respectively included in each pixel. The display device may include: a plurality of pixels connected to a plurality of scan lines, a plurality of control lines, a plurality of data lines, and a plurality of sensing lines; a scan driving unit that supplies scan signals to the plurality of scan lines and control signals to the plurality of control lines; a data driving unit that supplies one of an image data signal and a sensing data signal to the plurality of data lines; and a sensing unit including an analog-to-digital converter that converts the sensed values ​​supplied through the plurality of sensing lines into a digital current code, and corrects the current code based on the conversion characteristics of the analog-to-digital converter, and senses the characteristics of the driving transistors based on the corrected current code.

[0010] According to one embodiment, the sensing period may include: a first sensing period, during which a first sensing value is extracted based on a first sensing data signal corresponding to a first grayscale; and a second sensing period, during which a second sensing value is extracted based on a second sensing data signal corresponding to a second grayscale.

[0011] According to one embodiment, the data driving unit may supply the first sensing data signal to at least one of the plurality of pixels during the first sensing period, and supply the second sensing data signal to at least one of the plurality of pixels during the second sensing period.

[0012] According to one embodiment, the characteristics of the driving transistor may include mobility characteristics and threshold voltage characteristics, and the sensing unit may simultaneously calculate the mobility characteristics and threshold voltage characteristics of the driving transistor using the first sensing value and the second sensing value.

[0013] According to one embodiment, the analog-to-digital converter may generate a first current code corresponding to the first sensed value and a second current code corresponding to the second sensed value.

[0014] According to one embodiment, the sensing unit may further include: a code correction unit, which corrects the first current code and the second current code to a first correction code and a second correction code respectively based on the first sensing value and the second sensing value supplied to the analog-to-digital converter; and a compensation unit, which calculates the first correction code and the second correction code to jointly calculate the mobility characteristic and the threshold voltage characteristic of the driving transistor, and determines the compensation value of the image data based on the calculated mobility characteristic and the threshold voltage characteristic.

[0015] According to one embodiment, the code correction unit may include: a gain determination unit that determines a first gain corresponding to the first sensing value and a second gain corresponding to the second sensing value; and a calculation unit that applies the first gain to the first current code to calculate the first correction code, and applies the second gain to the second current code to calculate the second correction code.

[0016] According to one embodiment, the gain determination unit may include a lookup table, which is configured with a plurality of reference gains corresponding to a plurality of pre-set reference voltages.

[0017] According to one embodiment, the gain determination unit may further include an interpolation unit that interpolates a portion of the plurality of reference voltages to the first sensing value and the second sensing value respectively to calculate the first gain and the second gain.

[0018] According to one embodiment, the sensing unit may further include a memory for storing at least one of the first correction code and the second correction code.

[0019] According to one embodiment, the sensing unit may further include: a code correction unit, which corrects the first current code and the second current code to a first correction code and a second correction code based on the first grayscale and the second grayscale, respectively; and a compensation unit, which calculates the first correction code and the second correction code to jointly calculate the mobility characteristic and the threshold voltage characteristic of the driving transistor, and determines the compensation value of the image data based on the calculated mobility characteristic and the threshold voltage characteristic.

[0020] According to one embodiment, the code correction unit may include: a gain determination unit that determines a first gain corresponding to the first gray level and a second gain corresponding to the second gray level; and a calculation unit that applies the first gain to the first current code to calculate the first correction code, and applies the second gain to the second current code to calculate the second correction code.

[0021] According to one embodiment, the gain determination unit may include: a lookup table, which is configured with multiple reference gains corresponding to multiple pre-defined reference gray levels.

[0022] According to one embodiment, the code correction unit may include: a gain determination unit that determines a first gain corresponding to the first grayscale and a second gain corresponding to the second grayscale; and a calculation unit that applies the first gain to the first sensed value to calculate a first sensed correction value, and applies the second gain to the second current code to calculate a second sensed correction value. Alternatively, the analog-to-digital converter may convert the first sensed correction value and the second sensed correction value into the first correction code and the second correction code, respectively.

[0023] According to one embodiment, the pixel located on the i-th horizontal line (where i is a natural number) among the plurality of pixels may include: a light-emitting element; a first transistor, corresponding to the voltage of the first node to control the current flowing from the first power supply to the second node, and the first transistor being equivalent to the driving transistor; a second transistor, connected between the first node and one of the plurality of data lines, and its gate electrode being connected to the i-th scan line; a third transistor, connected between the second node and the j-th sensing line, and its gate electrode being connected to the i-th control line; and an energy storage capacitor, connected between the first node and the second node.

[0024] According to one embodiment, the length of the control signal supplied during the sensing period may be longer than the length of the control signal supplied during the display period.

[0025] According to one embodiment, a portion of the control signal supplied to the i-th control line during the sensing period may overlap with the scan signal supplied to the i-th scan line, and the control signal may be supplied for a longer period than the scan signal.

[0026] To achieve an objective of the present invention, the driving method of the display device according to various embodiments of the present invention may include: a step of supplying a first sensing data signal corresponding to a first grayscale to a pixel during a first sensing period; a step of supplying a first sensing value generated based on the first sensing data signal from the pixel to an analog-to-digital converter during the first sensing period; a step of correcting a first current code corresponding to the first sensing value to a first correction code in accordance with the grayscale transformation characteristics based on the analog-to-digital converter; a step of supplying a second sensing data signal corresponding to a second grayscale to the pixel during a second sensing period; a step of supplying a second sensing value generated based on the second sensing data signal from the pixel to the analog-to-digital converter during the second sensing period; a step of correcting a second current code corresponding to the second sensing value to a second correction code in accordance with the transformation characteristics; and a step of calculating the mobility characteristics and threshold voltage characteristics of the driving transistor of the pixel together using the first correction code and the second correction code. The first sensing data signal and the second sensing data signal may be different from each other.

[0027] According to one embodiment, the first correction code may be calculated by applying a first gain corresponding to the first sense value or the first gray level to the first current code, and the second correction code may be calculated by applying a second gain corresponding to the second sense value or the second gray level to the second current code.

[0028] According to one embodiment, the driving method for the display device may further include the step of compensating for input image data based on the mobility characteristics and the threshold voltage characteristics.

[0029] (Invention Effects)

[0030] The display device and driving method of the present invention can be applied according to the magnitude of the voltage input to the analog-to-digital converter and / or the level of grayscale supplied during sensing, to differentiate the gain used for correcting the current code. Therefore, the actual conversion deviation of the analog-to-digital converter based on the input or grayscale can be reflected more accurately in the correction of the current code, thereby greatly reducing the compensation error of external compensation methods based on two-point current sensing. Thus, compensation efficiency can be maximized, and image quality can be improved.

[0031] However, the effects of the present invention are not limited to those described above, and various extensions can be made without departing from the spirit and scope of the present invention. Attached Figure Description

[0032] Figure 1 This is a block diagram illustrating the display device involved in various embodiments of the present invention.

[0033] Figure 2It means Figure 1 A diagram showing an example of the pixels and sensing elements included in a display device.

[0034] Figure 3 It means Figure 1 A timing diagram illustrating an example of the operation of a display device.

[0035] Figure 4 It means Figure 1 A timing diagram of an example of the operation of a display device during sensing.

[0036] Figure 5 It is used to illustrate based on Figure 2 A diagram illustrating an example of the grayscale transformation characteristics of an analog-to-digital converter included in the sensing unit.

[0037] Figures 6a to 6c It means Figure 2 A block diagram of an example of a code correction unit included in the sensing unit.

[0038] Figure 7a It means Figure 6a A diagram illustrating an example of the gain determination section included in the code correction section.

[0039] Figure 7b It means Figure 6b and Figure 6c A diagram illustrating an example of the gain determination section included in the code correction section.

[0040] Figure 8 It means Figure 6a The diagram shows other examples of the gain determination section included in the code correction section.

[0041] Figure 9 It means Figure 2 A block diagram of an example of a compensation unit included in the sensing unit.

[0042] Figure 10 This is a graph that schematically illustrates the error rate of the external compensation methods involved in various embodiments of the present invention.

[0043] Figure 11 This is a sequence diagram illustrating the driving methods of the display device according to various embodiments of the present invention. Detailed Implementation

[0044] Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the accompanying drawings. The same reference numerals are used for the same constituent elements in the drawings, and repeated descriptions of the same constituent elements are omitted.

[0045] Figure 1 This is a block diagram illustrating the display device involved in various embodiments of the present invention.

[0046] Reference Figure 1 The display device 1000 may include a pixel unit 100, a scan driving unit 200, a data driving unit 300, a sensing unit 400, a power supply unit 500, and a timing control unit 600.

[0047] Display device 1000 can be a flat panel display device, a flexible display device, a curved display device, a foldable display device, or a bendable display device. Furthermore, the display device can be used with transparent display devices, head-mounted display devices, wearable display devices, etc. Additionally, display device 1000 can be used with various electronic devices such as smartphones, desktop computers, smart tablets, TVs, and monitors.

[0048] On the other hand, the display device 1000 can be implemented using an organic light-emitting display device, a liquid crystal display device, or the like. However, this is just an example, and the configuration of the display device 1000 is not limited to this. For example, the display device 1000 can be a self-emissive display device that includes inorganic light-emitting elements.

[0049] In one embodiment, the display device 1000 can be driven in a manner that distinguishes between a display period for displaying an image and a sensing period for sensing the characteristics of the driving transistors included in each pixel PX.

[0050] The pixel unit 100 includes a plurality of pixels PX configured to be connected to data lines DL1 to DLm (where m is a natural number), scan lines SL1 to SLn (where n is a natural number), control lines CL1 to CLn, and sensing lines SSL1 to SSLm. The plurality of pixels PX can receive voltage supplies from a first power supply VDD and a second power supply VSS from an external source.

[0051] On the other hand, Figure 1 The diagram shows n scan lines SL1 to SLn, but the present invention is not limited thereto. As an example, one or more control lines, scan lines, light emission control lines, sensing lines, etc., can be added to the pixel section 100 corresponding to the circuit structure of the pixel PX.

[0052] In one embodiment, the plurality of transistors included in the pixel PX may be N-type oxide thin-film transistors. For example, the oxide thin-film transistor may be a low-temperature polycrystalline oxide (LTPO) thin-film transistor. However, this is an example, and N-type transistors are not limited thereto. For example, the active pattern (semiconductor layer) included in the transistor may include inorganic semiconductors (e.g., amorphous silicon, polysilicon) or organic semiconductors. Furthermore, at least one of the plurality of transistors included in the display device 1000 and / or the pixel PX may be replaced with a P-type transistor.

[0053] The timing control unit 600 can generate a data drive control signal DCS, a scan drive control signal SCS, and a power drive control signal PCS in correspondence with a synchronization signal supplied from an external source. Specifically, the data drive control signal DCS generated by the timing control unit 600 may be supplied to the data drive unit 300, the scan drive control signal SCS generated by the timing control unit 600 may be supplied to the scan drive unit 200, and the power drive control signal PCS generated by the timing control unit 600 may be supplied to the power supply unit 500.

[0054] Furthermore, the timing control unit 600 can supply image data CDATA compensated based on input image data IDATA to the data driving unit 300. The input image data IDATA and the compensated image data CDATA can include multiple grayscale information included in the grayscale range set in the display device.

[0055] Data-driven control signals (DCS) can include a source-start signal and a clock signal. The source-start signal controls the start point of data sampling. The clock signal can be used to control the sampling operation.

[0056] The scan drive control signal SCS can include a scan start signal, a control start signal, and a clock signal. The scan start signal controls the timing of the scan signals. The control start signal controls the timing of the control signals. The clock signal can be used to shift the scan start signal and / or the control start signal.

[0057] The power drive control signal PCS can control the supply and voltage level of the first power supply VDD and the second power supply VSS.

[0058] The timing control unit 600 can also control the operation of the sensing unit 400. For example, the timing control unit 600 can control the timing of supplying a reference voltage to a plurality of pixels PX through sensing lines SSL1 to SSLm and / or the timing of sensing the current generated in the pixels PX through sensing lines SSL1 to SSLm.

[0059] The scan drive unit 200 can receive a scan drive control signal SCS from the timing control unit 600. Having received the scan drive control signal SCS, the scan drive unit 200 can supply scan signals to scan lines SL1 to SLn and control signals to control lines CL1 to CLn.

[0060] As an example, the scan drive unit 200 can sequentially supply scan signals to scan lines SL1 to SLn. By sequentially supplying scan signals to scan lines SL1 to SLn, multiple pixels PX can be selected on a horizontal line basis. For this purpose, the scan signal can be set to a gate on-state voltage (e.g., a logic high level), causing the transistors included in the multiple pixels PX to be turned on.

[0061] Similarly, the scan drive unit 200 can supply control signals to control lines CL1 to CLn. The control signals can be used to sense (or extract) the drive current flowing through the pixels (i.e., the current flowing through the drive transistor). The timing and waveform of the supplied scan signals and control signals can be set differently depending on the display period and the sensing period.

[0062] On the other hand, Figure 1 This illustration shows a scan drive unit 200 outputting all scan signals and control signals, but it is not limited to this. For example, the scan drive unit 200 may include a first scan drive unit that supplies scan signals to the pixel unit 100 and a second scan drive unit that supplies control signals to the pixel unit 100.

[0063] The data driving unit 300 can receive data driving control signals (DCS) from the timing control unit 600. During sensing, the data driving unit 300 can supply the pixel unit 100 with data signals for pixel characteristic detection (e.g., sensing data signals). During display, the data driving unit 300 can supply the pixel unit 100 with data signals for image display based on compensated image data (CDATA).

[0064] The sensing unit 400 can generate a compensation value to compensate for the characteristic values ​​of pixel PX based on the sensing values ​​provided from the sensing lines SSL1 to SSLm. For example, the sensing unit 400 can detect and compensate for changes in the threshold voltage, movement, and characteristics of the light-emitting elements of the driving transistors included in pixel PX.

[0065] In one embodiment, the sensing unit 400 can detect a first sensing value corresponding to a first grayscale during a first sensing period, and can detect a second sensing value corresponding to a second grayscale during a second sensing period. Here, the first grayscale can be a first test grayscale used for sensing current, and the second grayscale can be a second test grayscale different from the first grayscale.

[0066] The sensing unit 400 can simultaneously calculate the threshold voltage characteristic and motion characteristic of the driving transistor of pixel PX using the calculation of the first and second sensing values, thereby compensating for the image data of the corresponding pixel PX. For example, the first and second sensing values ​​can be replaced (or transformed) with the induced current in the saturation region of the driving transistor. If the induced current and the voltage value corresponding to the first and second gray levels are applied to the current-voltage relationship in the saturation region of the driving transistor, two equations can be derived with the threshold voltage characteristic and the motion characteristic as variables. Solving the two equations allows the threshold voltage characteristic and motion characteristic of the driving transistor of the corresponding pixel PX to be calculated together.

[0067] The compensation method involved in the various embodiments of this application, which utilizes induced current for two grayscale values ​​to perform external compensation for pixel PX, can be defined as a two-point current sensing method.

[0068] In one embodiment, during the sensing period, the sensing unit 400 supplies a predetermined reference voltage (or initialization voltage) to a plurality of pixels PX via sensing lines SSL1 to SSLm, and receives current or voltage extracted from the pixels PX. The extracted current or voltage corresponds to a sensed value, and the sensing unit 400 can detect changes in the characteristics of the driving transistor based on the sensed value. Based on the detected characteristic changes, the sensing unit 400 can calculate a compensation value to compensate for the input image data IDATA. The compensation value can be provided to the timing control unit 600 or the data driving unit 300.

[0069] In one embodiment, the sensing unit 400 may include an analog-to-digital converter that converts the sensed values ​​supplied through the sensing lines SSL1 to SSLm into a digital current code. The sensing unit 400 may correct the current code in accordance with the conversion characteristics of the analog-to-digital converter, and calculate the characteristics of the driving transistor based on the corrected current code.

[0070] During the display period, the sensing unit 400 can supply the pixel unit 100 with a predetermined reference voltage for image display via the sensing lines SSL1 to SSLm.

[0071] exist Figure 1 The diagram shows a configuration of the sensing unit 400 independent of the timing control unit 600; however, at least a portion of the configuration of the sensing unit 400 may be included in the timing control unit 600. For example, the sensing unit 400 and the timing control unit 600 may be formed by a single driver IC. Further, the sensing unit 400 may be included in the data driver unit 300 or the timing control unit 600. Therefore, at least a portion of the sensing unit 400, the data driver unit 300, and the timing control unit 600 may be formed by a single driver IC.

[0072] The power supply unit 500 can supply the pixel unit 100 with a first power supply VDD and a second power supply VSS based on the power drive control signal PCS. In one embodiment, the first power supply VDD can determine the voltage of the first electrode of the driving transistor (e.g., the drain voltage), and the second power supply VSS can determine the cathode voltage of the light-emitting element.

[0073] Figure 2 It means Figure 1 A diagram showing an example of the pixels and sensing elements included in a display device.

[0074] exist Figure 2 For ease of explanation, pixel PXij, located on the i-th horizontal line and connected to the j-th data line DLj, is shown.

[0075] Reference Figure 2 The pixel PXij may include a light-emitting element LD, a first transistor T1 (driving transistor), a second transistor T2, a third transistor T3, and an energy storage capacitor Cst.

[0076] The first electrode (anode or cathode) of the light-emitting element LD is connected to the second node N2, and the second electrode (cathode or anode) is connected to the second power supply VSS. The light-emitting element LD generates light of a predetermined brightness in accordance with the amount of current supplied from the first transistor T1.

[0077] The first electrode of the first transistor T1 can be connected to the first power supply VDD, and the second electrode can be connected to the first electrode of the light-emitting element LD. The gate electrode of the first transistor T1 can be connected to the first node N1. The first transistor T1 can control the amount of current flowing to the light-emitting element LD in accordance with the voltage of the first node N1.

[0078] The first electrode of the second transistor T2 can be connected to the data line DLj, and the second electrode can be connected to the first node N1. The gate electrode of the second transistor T2 can be connected to the scan line SLi. The second transistor T2 is turned on when a scan signal is supplied to the scan line SLi, thereby transmitting the data signal from the data line DLj to the first node N1.

[0079] The third transistor T3 can be connected between the induction line SSLj and the second electrode (i.e., the second node N2) of the first transistor T1. The gate electrode of the third transistor T3 can be connected to the control line CLI. The third transistor T3 can be turned on when a control signal is supplied to the control line CLI, thereby electrically connecting the induction line SSLj and the second node N2 (i.e., the second electrode of the first transistor T1).

[0080] In one embodiment, if the third transistor T3 is turned on, the initialization voltage Vint can be supplied to the second node N2. In other embodiments, if the third transistor T3 is turned on, the current generated by the first transistor T1 can be supplied to the sensing unit 400.

[0081] The energy storage capacitor Cst can be connected between the first node N1 and the second node N2. The energy storage capacitor Cst can store the voltage corresponding to the voltage difference between the first node N1 and the second node N2.

[0082] On the other hand, in embodiments of the present invention, the circuit structure of pixel PXij is not limited to... Figure 2 As an example, the light-emitting element LD can also be located between the first power supply VDD and the first electrode of the first transistor T1.

[0083] In addition, a parasitic capacitor Cpara can also be formed between the gate electrode (i.e., the first node N1) and the drain electrode of the first transistor T1.

[0084] The induction line SSLj can be connected to an induction capacitor Cse that charges the induced voltage. Based on the voltage (or amount of charge) charged into the induction capacitor Cse, the induced current flowing to the induction line SSLj can be calculated. The induced current can be defined as the drive current in the saturation region of the first transistor T1.

[0085] In one embodiment, the sensing unit 400 connected to the sensing line SSLj may include a first switch SW1, a second switch SW2, an analog-to-digital converter 420, a code correction unit 430, a compensation unit 440, and a memory 460.

[0086] The first switch SW1 and the second switch SW2 can be turned on alternately. If the first switch SW1 is turned on, an initialization voltage Vint is supplied to the second node N2. Therefore, the voltage of the second node N2 (i.e., the source voltage of the first transistor T1) can be initialized to the initialization voltage Vint.

[0087] If the second switch SW2 is turned on, the induced current of pixel PXij can flow to the sensing unit 400. For example, the voltage (or charge) charged into the sensing capacitor Cse can be supplied to the analog-to-digital converter 420.

[0088] The analog-to-digital converter 420 can convert the sensed value (e.g., voltage value) supplied through the sensing line SSLj during a predetermined sampling period (or sensing period) into a digital current code. For example, the first sensed value SV1 during the first sensing period can be converted into a first current code C1, and the second sensed value SV2 during the second sensing period can be converted into a second current code C2.

[0089] In one embodiment, the first current code C1 and / or the second current code C2 can be stored in the memory 460. In this case, the current codes stored in the memory 460 can be read out during code correction.

[0090] The analog-to-digital converter 420 typically includes semiconductor components such as MOS (metal oxide semiconductor). Due to process variations caused by these components, the characteristics (output characteristics or conversion characteristics) of the analog-to-digital converter 420 may differ depending on the magnitude (or grayscale) of the voltage supplied to it. Consequently, the current code output from the analog-to-digital converter 420 may not reflect the actual induced value, potentially leading to compensation errors in the measured grayscale.

[0091] In particular, in the two-point current sensing method, when the voltage difference supplied to the analog-to-digital converter 420 is large, the detection error of the characteristics of the first transistor T1 caused by the error of the sensing value can only increase, and thus the degradation compensation efficiency may decrease.

[0092] The code correction unit 430 can correct the first current code C1 and the second current code C2 into a first correction code CC1 and a second correction code CC2 based on the first sensing value SV1 and the second sensing value SV2 (or the first gray level and the second gray level), respectively. That is, the code correction unit 430 can correct the actual characteristics of the analog-to-digital converter 420 to an ideal form for calculating the threshold voltage and mobility, thereby calculating the first correction code CC1 and the second correction code CC2.

[0093] The compensation unit 440 can calculate the mobility characteristics and threshold voltage characteristics of the first transistor T1 together with the first correction code CC1 and the second correction code CC2. Based on the mobility characteristics and the threshold voltage characteristics, the compensation unit 440 can determine the compensation value COMV of the input image data IDATA.

[0094] The memory 460 can store at least one of a first current code C1, a second current code C2, a first correction code CC1, and a second correction code CC2. Furthermore, the memory 460 can include conversion characteristic association information of the analog-to-digital converter 420. This conversion characteristic association information of the analog-to-digital converter 420 can be obtained through testing performed before the display device 1000 leaves the factory, and the corresponding information can be recorded in the memory 460.

[0095] According to an embodiment, the memory 460 may also include lookup tables, etc., required for image data compensation.

[0096] On the other hand, Figure 2The illustration shows a case where multiple transistors (T1 to T3) are NMOS, but the invention is not limited thereto. As an example, at least one of the multiple transistors (T1 to T3) may be formed by PMOS.

[0097] Figure 3 It means Figure 1 A timing diagram illustrating an example of the operation of a display device.

[0098] Reference Figures 1 to 3 The display device 1000 can be driven by a display period DP for displaying images and a sensing period SP for sensing the characteristics of the first transistor T1 included in each pixel PX.

[0099] In one embodiment, during the sensing period, SP can also compensate for image data based on the sensed characteristic information.

[0100] During the display period DP, the first switch SW1 can be set to be in the on state and the second switch SW2 to be in the off state. Therefore, an initial voltage Vint, which is a constant voltage, can be supplied to the induction lines SSL1 to SSLm.

[0101] During the display period DP, the scan drive unit 200 can sequentially supply scan signals to scan lines SL1 to SLn. Furthermore, during the display period DP, the scan drive unit 200 can sequentially supply control signals to control lines CL1 to CLn.

[0102] For the i-th horizontal line, both the scanning signal and the control signal can be supplied simultaneously. Therefore, the second transistor T2 and the third transistor T3 can be turned on or off simultaneously.

[0103] If the second transistor T2 is turned on, the data signal DS corresponding to the image data can be supplied to the first node N1. If the third transistor T3 is turned on, the initialization voltage Vint can be supplied to the second node N2. Therefore, the energy storage capacitor Cst can store the voltage corresponding to the voltage difference between the data signal DS and the initialization voltage Vint.

[0104] Here, since the initial voltage Vint is set to a constant voltage, the voltage stored in the energy storage capacitor Cst can be stably determined based on the data signal DS.

[0105] If the supply of scan signals and control signals to the i-th scan line SLi and the i-th control line CLi is interrupted, then the second transistor T2 and the third transistor T3 can be disconnected.

[0106] Then, the first transistor T1 can control the amount of current (driving current) supplied to the light-emitting element LD in accordance with the voltage stored in the energy storage capacitor Cst. As a result, the light-emitting element LD can emit light with a brightness corresponding to the driving current of the first transistor T1.

[0107] In one embodiment, during the sensing period SP, the scan drive unit 200 may sequentially supply scan signals to scan lines SL1 to SLn. Furthermore, during the display period DP, the scan drive unit 200 may sequentially supply control signals to control lines CL1 to CLn.

[0108] In one embodiment, the length of the control signal supplied by SP during the sensing period can be longer than the length of the control signal supplied by DP during the display period. Furthermore, during the sensing period SP, a portion of the control signal supplied to the i-th control line CLi can overlap with the scan signal supplied to the i-th scan line SLi. The length of the control signal can be longer than the length of the scan signal. For example, the control signal supplied to the i-th control line CLi can be supplied simultaneously with the scan signal supplied to the i-th scan line SLi, and the control signal can be supplied for a longer period than the scan signal.

[0109] If both the scan signal and the control signal are supplied simultaneously, the second transistor T2 and the third transistor T3 are turned on. At this time, the first switch SW1 is in the on state. If the second transistor T2 is turned on, the sensed data signal SGV (or sensed data voltage) can be supplied to the first node N1. Simultaneously, by turning on the third transistor T3, the initialization voltage Vint can be supplied to the second node N2. Thus, the energy storage capacitor Cst can store a voltage corresponding to the voltage difference between the sensed data signal SGV and the initialization voltage Vint.

[0110] Then, if the supply of the scan signal is interrupted, the second transistor T2 is turned off. If the second transistor T2 is turned off, the first node N1 floats. Consequently, the voltage at the second node N2 rises, generating an induced current through the first transistor T1. During this voltage rise, the induced current flows through the induction line SSLj, charging the induction capacitor Cse with charge (i.e., voltage). The rate of voltage rise can vary depending on the current capability, i.e., mobility, of the first transistor T1.

[0111] Furthermore, a voltage distribution occurs between the energy storage capacitor Cst and the parasitic capacitor Cpara through the parasitic capacitor Cpara, which may cause unexpected changes in the gate-source voltage. Therefore, compensation for the voltage drop caused by the parasitic capacitor Cpara can be performed simultaneously during compensation.

[0112] After the voltage rises within a predetermined time, the second switch SW2 is turned on, and the induction line SSLj and the analog-to-digital converter 420 of the induction unit 400 can be connected. Thus, the analog-to-digital converter 420 can generate a current code corresponding to the voltage charged to the induction capacitor Cse (i.e., the induced value or induced current).

[0113] As described above, the code correction unit 430 can correct the current code to remove errors caused by the conversion characteristics of the analog-to-digital converter 420. This significantly reduces the compensation error of external compensation methods based on two-point current sensing, maximizes compensation efficiency, and improves image quality.

[0114] According to an embodiment, at least one sensing period SP can be performed before the display device 1000 is shipped from the factory. In this case, initial characteristic information of the first transistor T1 is stored before the display device 1000 is shipped from the factory, and this initial characteristic information can be used to compensate for the input image data IDATA, so that the pixel unit 100 can display an image with uniform image quality.

[0115] Furthermore, in actual use of the display device 1000, a sensing period SP can be executed at predetermined intervals. For example, the sensing period SP can be configured for a portion of the time the display device 1000 is turned on and / or turned off. Therefore, even if the characteristics of the first transistor T1 of each pixel PX change corresponding to the usage amount, the characteristic information can be updated in real time to reflect this in the generation of the data signal. However, this is just an example; the sensing period SP can also be inserted between predetermined display periods DP. Therefore, the pixel unit 100 can continuously display an image with uniform image quality.

[0116] Figure 4 It means Figure 1 A timing diagram of an example of the operation of a display device during sensing.

[0117] Reference Figures 2 to 4 The sensing period SP may include a first sensing period SP1 and a second sensing period SP2.

[0118] The current sensing methods during the first sensing period SP1 and the second sensing period SP2 are actually the same.

[0119] During the first sensing period SP1, a first sensing data signal GV1 corresponding to the first grayscale can be supplied to the data line DLj. The first sensing value SV1 can be generated and extracted based on the first sensing data signal GV1.

[0120] During the second sensing period SP2, a second sensing data signal GV2 corresponding to the second grayscale can be supplied to the data line DLj. The second sensing value SV2 can be generated and extracted based on the second sensing data signal GV2.

[0121] On the other hand, the first gray level and the second gray level can be values ​​set experimentally. That is, the first gray level and the second gray level can be set to minimize the errors in the motion characteristics and threshold voltage characteristics. For example, when pixel PX emits light corresponding to a gray level range of 0 to 255, the first gray level can be a gray level of 224 and the second gray level can be a gray level of 128. However, this is just an example, and the first gray level and the second gray level are not limited to these.

[0122] Figure 5 It is used to illustrate based on Figure 2 A diagram illustrating an example of the grayscale transformation characteristics of an analog-to-digital converter included in the sensing unit.

[0123] Figure 5 Based on the absolute value of the gate-source voltage |Vgs| of the first transistor T1, the output of the current code CODE corresponding to the sensed value supplied to the analog-to-digital converter 420 is shown.

[0124] Reference Figure 2 and Figure 5 The analog-to-digital converter 420 can convert the input induced value (or voltage) into a digital current code (CODE) of a predetermined number of bits.

[0125] The analog-to-digital converter 420 can act as an intermediate medium for converting the voltage charged to the inductive capacitor Cse into the current domain. For example, the analog-to-digital converter 420 can output a 12-bit current code corresponding to the input voltage.

[0126] The compensation unit 440 can determine the value of the current code CODE, which is converted into digital form by the analog-to-digital converter 420, as the induced current (i.e., the drain current of the first transistor T1) and use it in the calculation of the compensation value.

[0127] The absolute value of the gate-source voltage, |Vgs|, can be determined based on the magnitude of the data signal or the initialization voltage, Vint. For example, a larger absolute value of the gate-source voltage, |Vgs|, corresponds to higher grayscale, and a smaller absolute value of the gate-source voltage, |Vgs|, corresponds to lower grayscale. Figure 5 In this context, the grayscale corresponding to the first voltage V1 can be lower than the grayscale corresponding to the second voltage V2.

[0128] The actual current code output characteristics of the analog-to-digital converter 420 (e.g., denoted as...) Figure 5The ACC may differ from the theoretical input-output relationship or the input-output relationship subject to predetermined calibration (e.g., denoted as...). Figure 5 (ICC). For example, such as Figure 5 As shown, the theoretical input-output relationship ICC can have a form that increases linearly with the magnitude of the input voltage. However, the actual current code output characteristic ACC of the practical analog-to-digital converter 420 may have a non-linear form.

[0129] In existing methods that use a sensed data signal corresponding to a grayscale level to sense the threshold voltage and mobility of the first transistor T1, only a specific current code region can be fixed. In this case, a single gain can be applied to the corresponding range of codes in order to calibrate the output of the analog-to-digital converter 420.

[0130] However, the two-point current sensing method of this application uses sensing data signals from two grayscale regions with high compensation accuracy to sense the threshold voltage and mobility. Therefore, compensation errors may occur when a single gain is applied.

[0131] For example, when the first voltage V1 and the second voltage V2 are test voltages corresponding to two grayscale values, the difference between the actual output second code CODE2 corresponding to the first voltage V1 and the ideal first code CODE1 may be different from the difference between the actual output fourth code CODE4 corresponding to the second voltage V2 and the ideal third code CODE3. Therefore, different gain values ​​should be applied to the second code CODE2 and the fourth code CODE4. For example, a first gain could be applied to the second code CODE2 to correct (or calibrate) it to the first code CODE1, and a second gain different from the first gain could be applied to the fourth code CODE4 to correct (or calibrate) it to the third code CODE3.

[0132] If the same gain (correction value) is applied to the second code CODE2 and the fourth code CODE4, an output error will occur, and the accuracy of the sensed data (e.g., sensed current) may decrease.

[0133] The code correction unit 430 in various embodiments of the present invention can apply different gains for correcting current codes based on the absolute value of the gate-source voltage |Vgs| and / or the grayscale supplied during induction. Therefore, the actual conversion deviation of the analog-to-digital converter 420 based on the input value is more accurately reflected in the correction of the current code, thereby significantly reducing the compensation error of the compensation unit 440.

[0134] Figures 6a to 6c It means Figure 2 A block diagram of an example of a code correction unit included in the sensing unit.

[0135] Reference Figure 2 , Figures 6a to 6c The code correction unit 430 may include a gain determination unit 432 and an arithmetic unit 434, the code correction unit 430A may include a gain determination unit 432A and an arithmetic unit 434A, and the code correction unit 430B may include a gain determination unit 432B and an arithmetic unit 434B.

[0136] In one embodiment, such as Figure 6a and Figure 6b As shown, the code correction units 430 and 430A can correct the current codes (C1, C2) output from the analog-to-digital converter 420.

[0137] like Figure 6a As shown, the gain determination unit 432 can receive a first sensing value SV1 and a second sensing value SV2 supplied from the sensing line SSLj. The gain determination unit 432 can determine a first gain G1 corresponding to the first sensing value SV1, and can determine a second gain G2 corresponding to the second sensing value SV2. The first gain G1 and the second gain G2 can be supplied to the calculation unit 434.

[0138] For example, the gain determination unit 432 may include a lookup table storing multiple gains corresponding to multiple predetermined voltages (see reference). Figure 7a The gain determination unit 432 can output a first gain G1 and a second gain G2 from a lookup table for the voltages corresponding to the first sensed value SV1 and the second sensed value SV2, respectively. For example, the first gain G1 and the second gain G2 can be in digital form. However, this is just an example, and the configuration for determining the gain is not limited to this. For example, the gain determination unit 432 may include a hardware / software configuration that implements a functional expression of the relationship between the input voltage and the gain, and may further include a configuration for determining the gain by interpolating the values ​​set in the lookup table.

[0139] The gain can be set within the range of 0 to 1. This gain can be determined by input / output testing (experiment) of the analog-to-digital converter 420 before the product leaves the factory.

[0140] The arithmetic unit 434 can receive the supply of a first current code C1 and a second current code C2 from the analog-to-digital converter 420, and can receive the supply of a first gain G1 and a second gain G2 from the gain determination unit 432. The arithmetic unit 434 can apply the first gain G1 to the first current code C1 to generate a first correction code CC1. Similarly, the arithmetic unit 434 can apply the second gain G2 to the second current code C2 to generate a second correction code CC2. For example, the arithmetic unit 434 may include a multiplier that performs a digital multiplication operation between the current code and the gain.

[0141] Therefore, the first correction code CC1 and the second correction code CC2 can have digital values. The first correction code CC1 and the second correction code CC2 can be supplied to the compensation unit 440.

[0142] On the other hand, according to the embodiment, at least a portion of the sensing values ​​(SV1, SV2), current codes (C1, C2), gains (G1, G2), and correction codes (CC1, CC2) can be stored in a memory such as a line buffer and read when required for the corresponding operation.

[0143] In one embodiment, such as Figure 6b As shown, the gain determination unit 432A can receive a first gray level TG1 and a second gray level TG2 corresponding to the sensing data signal supplied to pixel PXij by SP during sensing. The gain determination unit 432A can determine a first gain G1 corresponding to the first gray level TG1, and can determine a second gain G2 corresponding to the second gray level TG2. The first gain G1 and the second gain G2 can be supplied to the arithmetic unit 434A.

[0144] That is, different from Figure 6a Implementation examples, Figure 6b The gain determination unit 432A can determine the gain based on the input grayscale used for pixel emission. For example, the gain determination unit 432A may include a lookup table storing multiple gains corresponding to multiple predetermined grayscales (or reference grayscales) (see reference). Figure 7b The gain determination unit 432 can output the first gain G1 and the second gain G2 corresponding to the first gray level TG1 and the second gray level TG2 from the lookup table, respectively.

[0145] The arithmetic unit 434A can apply a first gain G1 to the first current code C1 to calculate the first correction code CC1, and can apply a second gain G2 to the second current code C2 to calculate the second correction code CC2. The configuration and operation of the arithmetic unit 434A are similar to... Figure 6a The arithmetic unit 434 is essentially the same, so repeated explanations are omitted.

[0146] In one embodiment, such as Figure 6cAs shown, the code correction unit 430B can perform analog calculations to provide the analog-to-digital converter 420 with a first inductive correction value CSV1 and a second inductive correction value CSV2.

[0147] That is, different from Figure 6b Implementation examples, Figure 6c The code correction unit 430B can provide the analog-to-digital converter 420 with the result of the correction operation (e.g., analog operation) on the sensed values ​​(SV1, SV2).

[0148] The gain determination unit 432B can receive a first gray level TG1 and a second gray level TG2 corresponding to the sensing data signal supplied by SP to pixel PXij during sensing. The gain determination unit 432B can determine a first gain G1 corresponding to the first gray level TG1 and a second gain G2 corresponding to the second gray level TG2. The first gain G1 and the second gain G2 can be supplied to the arithmetic unit 434B. In one embodiment, the first gain G1 and the second gain G2 can have analog voltage values.

[0149] The arithmetic unit 434B can receive a first sensing value SV1 and a second sensing value SV2 in analog form. The arithmetic unit 434B can apply a first gain G1 to the first sensing value SV1 to calculate a first sensing correction value CSV1, and can apply a second gain G2 to the second sensing value SV2 to calculate a second sensing correction value CSV2. The arithmetic unit 434B may include an analog multiplier that performs analog multiplication operations.

[0150] The first induction correction value CSV1 and the second induction correction value CSV2 can be provided to the analog-to-digital converter 420.

[0151] As described above, the gain used to correct the current code can be appropriately determined based on the voltage level of the sensed values ​​(SV1, SV2) supplied to the analog-to-digital converter 420 or the grayscale (TG1, TG2) used for sensing.

[0152] Figure 7a It means Figure 6a A diagram illustrating an example of the gain determination section included in the code correction section.

[0153] Reference Figure 6a and Figure 7a The gain determination unit 432 may include a lookup table with a reference gain RG corresponding to a set reference voltage RV.

[0154] The reference gain RG for each of the first reference voltage RV1 to the ninth reference voltage RV9 can be determined through testing performed before the product leaves the factory. In one embodiment, for the voltage between the first reference voltage RV1 and the second reference voltage RV2, the gain can be determined as the reference gain RG corresponding to the first reference voltage RV1, i.e., 0.692. Similarly, for the voltage between the second reference voltage RV2 and the third reference voltage RV3, the gain can be determined as the reference gain RG corresponding to the second reference voltage RV2, i.e., 0.688.

[0155] Conversely, for the voltage between the first reference voltage RV1 and the second reference voltage RV2, the gain can be determined as the reference gain RG corresponding to the second reference voltage RV2, i.e., 0.688, and for the voltage between the second reference voltage RV2 and the third reference voltage RV3, the gain can be determined as the reference gain RG corresponding to the third reference voltage RV3, i.e., 0.680.

[0156] However, this is just an example, and the method of determining the gain from a lookup table based on the magnitude of the voltage supplied to the gain determination unit 432 is not limited to this.

[0157] Figure 7b It means Figure 6b and Figure 6c A diagram illustrating an example of the gain determination section included in the code correction section.

[0158] Reference Figure 6b , Figure 6c as well as Figure 7b The gain determination units 432A and 432B may include a lookup table containing a reference gain RG corresponding to a pre-set reference gray level RGL.

[0159] That is, different from Figure 7a The gain applicable to the current code can be determined by referring to the grayscale of the image data supplied for sensing.

[0160] The reference gain RG for each of the first reference grayscale G0 to the ninth reference grayscale G255 can be determined by testing performed before the product leaves the factory.

[0161] The method of determining gain using a lookup table has been referenced. Figure 7a Detailed explanations have been provided, therefore repeated explanations have been omitted.

[0162] For example, in the case of two-point current sensing of 192 grayscale G192 and 128 grayscale G128, the output of the analog-to-digital converter 420 before applying gain can be 1408 codes for 192 grayscale G192 and 945 codes for 128 grayscale G128. However, based on the lookup tables of the gain determination units 432A and 432B, the values ​​can be determined to be different from each other, that is, the gain of 192 grayscale G192 is 0.680 and the gain of 128 grayscale G128 is 0.672.

[0163] Therefore, when sensing 192 grayscale G192, the final correction code is determined to be code 957 (1408×0.680, after removing the decimal places), and when sensing 128 grayscale G128, the final correction code is determined to be code 635 (945×0.672, after removing the decimal places).

[0164] As described above, the gain of the current code used for correction is reflected according to the grayscale distinction supplied for external compensation, thereby reducing or minimizing the compensation error caused by the conversion characteristics of the analog-to-digital converter 420.

[0165] Figure 8 yes Figure 6a The diagram shows other examples of the gain determination section included in the code correction section.

[0166] Reference Figures 6a to 8 The gain determination unit 432 may include a lookup table 4321 and an interpolation unit 4322.

[0167] Lookup table 4321 can include the relationship between voltage and gain or the relationship between grayscale and gain. Lookup table 4321 has been referenced. Figure 7a or Figure 7b Detailed explanations have been provided, therefore repeated explanations have been omitted.

[0168] In one embodiment, the interpolation unit 4322 can interpolate a portion of the plurality of reference voltages RV to a first sensed value SV1 to calculate a first gain G1 corresponding to the first sensed value SV1, and can interpolate a portion of the plurality of reference voltages RV to a second sensed value SV2 to calculate a second gain G2 corresponding to the second sensed value SV2. For example, referring to... Figure 7a and Figure 8 For the voltage between the first reference voltage RV1 and the second reference voltage RV2, the gain corresponding to the corresponding voltage can also be determined by using various interpolation methods of the first reference voltage RV1, the second reference voltage RV2, the first reference gain (e.g., 0.692), and the second reference gain (e.g., 0.688).

[0169] In one embodiment, the interpolation unit 4322 can interpolate a portion of the plurality of reference gray levels RGL to a first gray level TG1 to calculate a first gain G1 corresponding to the first gray level TG1, and can interpolate a portion of the plurality of reference gray levels RGL to a second gray level TG2 to calculate a second gain G2 corresponding to the second gray level TG2. For example, referring to... Figure 7b and Figure 8 For gray levels between 192 (G192) and 224 (G224), the gain corresponding to the gray level can be determined by using various interpolation methods of 192 (G192), 224 (G224), reference gain RG-0.680, and reference gain RG-0.688.

[0170] Therefore, the gain used to correct the current code can be appropriately determined based on the voltage level of the sensed values ​​(SV1, SV2) or the grayscale values ​​(TG1, TG2) used for sensing. This reduces the error in the current code caused by the conversion characteristics of the analog-to-digital converter 420.

[0171] Figure 9 It means Figure 2 A block diagram of an example of a compensation unit included in the sensing unit.

[0172] Reference Figures 1 to 9 The compensation unit 440 may include a lookup table 442, a first arithmetic unit 444, and a second arithmetic unit 446.

[0173] The compensation unit 440 can calculate the motion characteristics and threshold voltage characteristics of the first transistor T1 using the first correction code CC1 and the second correction code CC2. Based on the calculated motion characteristics and threshold voltage characteristics, the compensation unit 440 can determine the compensation value COMV of the image data IDATA.

[0174] When displaying images and performing sensing, the source voltage Vs is fixed at the initialization voltage Vint. Therefore, for a predetermined grayscale, the degradation of the first transistor T1 can be compensated by adjusting the gate voltage of the first transistor T1.

[0175] That is, the compensation value COMV can be the value used to adjust the data signal (i.e., the voltage supplied to the gate electrode of the first transistor T1) corresponding to a predetermined gray level.

[0176] Lookup table 442 can output the first gate-source voltage Vgs_dis corresponding to the input image data IDATA. For example, lookup table 442 may include a digital-to-analog converter. Furthermore, lookup table 442 can be updated to reflect the relationship between the new input image data IDATA and the gate-source voltage Vgs_dis each time image data is compensated.

[0177] For example, if the first gray level corresponding to the first sensed data signal GV1 is supplied to lookup table 442, then lookup table 442 can output the first gate-source voltage corresponding to the first gray level. If the second gray level corresponding to the second sensed data signal GV2 is supplied to lookup table 442, then lookup table 442 can output the second gate-source voltage corresponding to the second gray level.

[0178] The first arithmetic unit 444 can calculate the gain G and bias OS for compensating the gate-source voltage Vgs_dis based on the first correction code CC1 and the second correction code CC2. The first correction code CC1 can correspond to the first induced current, and the second correction code CC2 can correspond to the second induced current.

[0179] The first arithmetic unit 444 can calculate the gain G, which includes mobility characteristics, and the bias OS, which includes threshold voltage characteristics, based on the following [Mathematical Formula 1].

[0180] [Mathematical Expression 1]

[0181]

[0182] Here, Id can be the drive current, β can be a variable including mobility characteristics, Vgs can be the gate-source voltage, and Vth can be the threshold voltage.

[0183] In [Mathematical Formula 1], the drive current Id is applied with a first induced current (e.g., Id1) corresponding to the first correction code CC1 or a second induced current (e.g., Id2) corresponding to the second correction code CC2, and the gate-source voltage Vgs is based on the first induced data signal ( Figure 4 GV1) or second sensing data signal ( Figure 4 The constant of GV2), β and Vth are variables.

[0184] Therefore, the first arithmetic unit 444 can calculate β and Vth by solving two sets of equations based on the first induced current Id1 and the second induced current Id2. The gain G includes the mobility characteristic β, which can be multiplied onto the gate-source voltage Vgs_dis. The bias OS can include the threshold voltage Vth characteristic, which can be added onto the first gate-source voltage Vgs_dis. That is, the first arithmetic unit 444 can simultaneously calculate the mobility characteristic β and the threshold voltage Vth characteristic of the first transistor T1 using the first correction code CC1 and the second correction code CC2.

[0185] The second arithmetic unit 446 can calculate a compensation value COMV for compensating the gate-source voltage Vgs_dis. In one embodiment, the second arithmetic unit 446 can multiply the gain G on the first gate-source voltage Vgs_dis and add the bias OS to the calculated value. Thus, a compensation value COMV can be calculated for one input image data IDATA corresponding to one pixel PX. The compensation value COMV is equivalent to updating the gate-source voltage Vgs_dis. The input image data IDATA can be compensated based on the compensation value COMV to correspond to the voltage of the updated data signal.

[0186] As described above, the mobility characteristic β and threshold voltage Vth characteristic of the first transistor T1 can be simultaneously calculated based on the first correction code CC1 and the second correction code CC2 (i.e., the induced current) sensed through a two-point current sensing method, thereby compensating for the input image data. Since the characteristic deviation of the analog-to-digital converter 420 used for sensing is corrected, the errors in the calculated mobility characteristic β and threshold voltage Vth characteristic are greatly reduced, maximizing compensation efficiency and improving image quality.

[0187] Figure 10 This is a graph that schematically illustrates the error rate of the external compensation methods involved in various embodiments of the present invention.

[0188] Reference Figure 10 The error rate of the external compensation method based on the driving current sensing for the first gray level and the second gray level can vary depending on the value of the first gray level and the value of the second gray level.

[0189] Figure 10 This indicates the grayscale error rate when the source voltage of the first transistor T1 is initialized to 1.5V. Specifications such as G255, G224, and G192 may refer to the first and second grayscale values ​​set for two-point current sensing.

[0190] The display device 1000 according to various embodiments of the present invention can reflect errors caused by the conversion characteristics of the analog-to-digital converter based on the magnitude of the voltage supplied to the analog-to-digital converter in two-point current sensing. That is, when performing current sensing for a first gray level, a first gain corresponding to the first gray level or the first sensing value can be applied to the current code, and when performing current sensing for a second gray level, a second gain corresponding to the second gray level or the second sensing value can be applied to the current code.

[0191] Therefore, errors caused by the conversion characteristics of the analog-to-digital converter can be removed or minimized, such as Figure 10As shown, this can significantly improve the error rate of external compensation based on two-point current sensing. Therefore, it can improve the degradation compensation efficiency of pixels and display devices, as well as image quality.

[0192] Figure 11 This is a sequence diagram illustrating the driving methods of the display device according to various embodiments of the present invention.

[0193] Reference Figure 11 The driving method of the display device can, during a first sensing period, supply a first sensing data signal corresponding to a first grayscale (or a first test grayscale) to the pixel (S100), and during the first sensing period, supply a first sensing value generated based on the first sensing data signal from the pixel to the analog-to-digital converter (S200), and correct a first current code corresponding to the first sensing value to a first correction code based on the grayscale transformation characteristics based on the analog-to-digital converter (S300). Furthermore, the driving method of the display device can, during a second sensing period, supply a second sensing data signal corresponding to a second grayscale to the pixel (S400), and during the second sensing period, supply a second sensing value generated based on the second sensing data signal from the pixel to the analog-to-digital converter (S500), and correct a second current code corresponding to the second sensing value to a second correction code based on the transformation characteristics (S600). Then, the driving method of the display device can use the first correction code and the second correction code together to calculate the mobility characteristics and threshold voltage characteristics of the driving transistor of the pixel (S700).

[0194] In one embodiment, the first grayscale and the second grayscale are different from each other, thereby the first sensed data signal and the second sensed data signal have different voltage levels.

[0195] In one embodiment, the first correction code can be calculated by applying a first gain corresponding to the first sensing value or the first gray level to the first current code, and the second correction code can be calculated by applying a second gain corresponding to the second sensing value or the second gray level to the second current code.

[0196] On the other hand, the mobility characteristics and threshold voltage characteristics of the driving transistor can be calculated simultaneously during the first and second sensing periods. Compared to the external compensation sensing method in the prior art, where the operations for sensing the mobility characteristics and the operations for sensing the threshold voltage characteristics are different, the driving method of the display device of the present invention can simultaneously calculate the mobility characteristics and threshold voltage characteristics using two induced currents induced during the first and second sensing periods. Therefore, the sensing time can be shortened and the accuracy of real-time sensing can be improved.

[0197] In one embodiment, the driving method of the display device may further include compensating for input image data based on the calculated characteristics of the driving transistors (S800).

[0198] The driving method for this display device has been passed... Figures 1 to 9 Detailed explanation is provided, therefore repeated explanations are omitted.

[0199] As described above, the display device and its driving method according to the embodiments of the present invention can be applied by differentiating the gain used for correcting the current code based on the magnitude of the voltage input to the analog-to-digital converter 420 and / or the level of grayscale supplied during sensing. Therefore, the actual transformation deviation of the analog-to-digital converter 420 based on the input or grayscale is more accurately reflected in the correction of the current code, thereby greatly reducing the compensation error of external compensation methods based on two-point current sensing. Thus, compensation efficiency can be maximized, and image quality can be improved.

[0200] The above describes various embodiments of the present invention. However, those skilled in the art should understand that various modifications and changes can be made to the present invention without departing from the spirit and scope of the invention as described in the claims.

Claims

1. A display device that is driven by dividing a display period for displaying an image and a sensing period for sensing characteristics of a drive transistor included in each pixel, respectively, the display device comprising: a plurality of pixels connected to a plurality of scan lines, a plurality of control lines, a plurality of data lines, and a plurality of sensing lines; a scan driving section that supplies a scan signal to the plurality of scan lines and supplies a control signal to the plurality of control lines; a data driving section that supplies one of an image data signal and a sensing data signal to the plurality of data lines; a sensing section that includes an analog-digital converter that converts a sensing value supplied through the plurality of sensing lines into a digital current code, corrects the current code in reflection of a conversion characteristic of the analog-digital converter, and senses characteristics of the drive transistor based on the corrected current code, the sensing period including a first sensing period in which a first sensing value is extracted based on a first sensing data signal corresponding to a first gray scale and a second sensing period in which a second sensing value is extracted based on a second sensing data signal corresponding to a second gray scale; the analog-digital converter generating a first current code corresponding to the first sensing value or the first gray scale and a second current code corresponding to the second sensing value or the second gray scale; the sensing section further including: a code correction section that corrects the first current code to a first corrected code based on a first gain corresponding to the first sensing value or the first gray scale and corrects the second current code to a second corrected code based on a second gain corresponding to the second sensing value or the second gray scale; and the code correction section including: a look-up table in which a plurality of reference gains corresponding to a plurality of reference voltages or a plurality of reference gray scales that have been set are set; and an interpolation section that interpolates a part of the plurality of reference voltages set to the first sensing value and the second sensing value, respectively, to calculate the first gain and the second gain or interpolates a part of the plurality of reference gray scales set to the first gray scale and the second gray scale, respectively, to calculate the first gain and the second gain.

2. The display device according to claim 1, wherein the data driving section supplies the first sensing data signal to at least one of the plurality of pixels in the first sensing period, and supplies the second sensing data signal to at least one of the plurality of pixels in the second sensing period.

3. The display device according to claim 1, wherein the characteristics of the drive transistor include mobility characteristics and threshold voltage characteristics, and the sensing section simultaneously calculates the mobility characteristics and the threshold voltage characteristics of the drive transistor using the first sensing value and the second sensing value.

4. The display device according to claim 3, wherein the sensing section further includes: ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The compensation section calculates the first correction code and the second correction code to calculate the mobility characteristic and the threshold voltage characteristic of the drive transistor together, and determines a compensation value of image data based on the calculated mobility characteristic and threshold voltage characteristic.

5. The display device according to claim 4, wherein The code correction section includes: a gain determination section that determines the first gain corresponding to the first sensed value and the second gain corresponding to the second sensed value; and a calculation section that calculates the first correction code by applying the first gain to the first current code and calculates the second correction code by applying the second gain to the second current code.

6. The display device according to claim 5, wherein The gain determination section includes the lookup table and the interpolation section, The sensing section further includes a memory that stores at least one of the first correction code and the second correction code.

7. The display device according to claim 1, wherein The code correction section includes: a gain determination section that determines the first gain corresponding to the first gray scale and the second gain corresponding to the second gray scale; and a calculation section that calculates the first correction code by applying the first gain to the first current code and calculates the second correction code by applying the second gain to the second current code.

8. The display device according to claim 1, wherein The code correction section includes: a gain determination section that determines the first gain corresponding to the first gray scale and the second gain corresponding to the second gray scale; and a calculation section that calculates a first sensed correction value by applying the first gain to the first sensed value and calculates a second sensed correction value by applying the second gain to the second sensed value, The analog-digital converter converts the first sensed correction value and the second sensed correction value into the first correction code and the second correction code, respectively.

9. The display device according to claim 1, wherein The pixel located at the i-th horizontal line among the plurality of pixels includes: a light emitting element; a first transistor that controls a current flowing from a first power supply to a second node in response to a voltage of a first node, and that corresponds to the drive transistor; a second transistor connected between the first node and one of the plurality of data lines, and having a gate electrode connected to an i-th scan line; a third transistor connected between the second node and a j-th sensing line, and having a gate electrode connected to an i-th control line; and an energy storage capacitor connected between the first node and the second node, where i is a natural number, and the length of the control signal supplied during the sensing period is longer than the length of the control signal supplied during the display period, a portion of the control signal supplied to the i-th control line during the sensing period overlaps with the scan signal supplied to the i-th scan line, and the control signal is supplied for a longer time than the scan signal. ​ ​

Images