Display device

Abstract

A display device is disclosed. The display device includes a display panel including a plurality of pixels; a scan driving section supplying a scan signal to a plurality of scan lines connected to each of the pixels and supplying a sensing signal to a plurality of sensing lines connected to each of the pixels; a data driving section supplying a data signal corresponding to image data to a plurality of data lines connected to each of the pixels; a sensing section sensing a threshold voltage of a first transistor included in each of the pixels through each reception line connected to each of the pixels and correcting the sensed threshold voltage based on a voltage drop caused by at least one of an internal resistance of the data line and an internal resistance of the reception line; and a timing control section generating the image data by changing input image data based on the corrected threshold voltage.

Description

Technical Field

[0001] This invention relates to display devices, and more specifically to display devices and driving methods thereof. Background Technology

[0002] With the advancement of information technology, the importance of display devices, as the connection medium between users and information, has received increasing attention. Correspondingly, the use of display devices such as liquid crystal displays (LCDs), organic light-emitting displays (OLEDs), and plasma displays (Plasma displays) is increasing.

[0003] Each pixel of the display device can emit light with a brightness corresponding to the data voltage supplied through the data line. The display device can display image frames by combining the light emitted by each pixel.

[0004] Each data line can be connected to multiple pixels. Therefore, a scan driver is needed to provide a scan signal for selecting the pixel from among the multiple pixels to which a data voltage should be supplied. The scan driver can be configured as a shift register, thereby providing scan signals with on-level values ​​sequentially on a scan line basis.

[0005] In addition, receiving lines can be connected to multiple pixels as needed to sense the movement of the driving transistor of the pixel, threshold voltage characteristics, degradation characteristics of the light-emitting element, etc. Summary of the Invention

[0006] One object of the present invention is to provide a display device that senses the voltage drop caused by the wiring resistance of the data line and the receiving line, thereby correcting the threshold voltage sensed in each pixel, and externally compensating the data signal to each pixel with an amount corresponding to the corrected threshold voltage.

[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 the aforementioned objective, one aspect of the present invention provides a display device.

[0010] The display device may include: a display panel including a plurality of pixels; a scan driving unit that supplies scan signals to a plurality of scan lines connected to each of the pixels and supplies sensing signals to a plurality of sensing lines connected to each of the pixels; a data driving unit that supplies data signals corresponding to image data to a plurality of data lines connected to each of the pixels; a sensing unit that senses the threshold voltage of a first transistor included in each of the pixels through a receiving line connected to each of the pixels, and corrects the sensed threshold voltage based on the voltage drop caused by at least one of the internal resistance of the data line and the internal resistance of the receiving line; and a timing control unit that generates the image data by changing the input image data based on the corrected threshold voltage.

[0011] The sensing unit may include: a threshold voltage sensing unit for sensing the threshold voltage of the first transistor; a voltage drop sensing unit for sensing the voltage drop, taking at least two pixels selected from the plurality of pixels that are connected to the j-th (j is a natural number greater than 1) data line and the j-th receive line as objects, and using the sensed voltage drop to calculate the voltage drop for each of the object pixels; an offset voltage calculation unit for calculating an offset voltage to compensate for the voltage drop; and an offset voltage addition unit for adding the threshold voltage sensed for the object pixel to the offset voltage and outputting it.

[0012] The selected at least two pixels may include: a first pixel disposed on a first horizontal line of the display panel; and a second pixel disposed on a last horizontal line of the display panel.

[0013] Alternatively, the sensing unit and the data driving unit may be configured together on one side of the display panel.

[0014] Alternatively, the scan driving unit may supply scan signals and sensing signals to the scan line and sensing line connected to the first pixel, respectively, and the data driving unit may supply a reference voltage determined based on the threshold voltage sensed for the first pixel to the data line connected to the first pixel.

[0015] Alternatively, the reference voltage may be a voltage obtained by adding the voltage of the first power supply and the threshold voltage sensed by the first transistor for the first pixel.

[0016] It is possible that the voltage drop sensed for the selected at least two pixels includes the voltage drop caused by the internal resistance of the line to which the first power supply is applied.

[0017] Alternatively, the voltage drop sensing unit may calculate the maximum voltage drop by differentially analyzing the first voltage drop sensed for the first pixel and the second voltage drop sensed for the second pixel.

[0018] Alternatively, the voltage drop sensing unit may interpolate the maximum voltage drop based on the number of horizontal lines configured with the plurality of pixels, thereby calculating the voltage drop for each of the object pixels.

[0019] The object pixel may include: a first transistor connected between a first power source and a second node, and including a gate electrode connected to the first node; a second transistor connected between the j-th data line and the first node, and including a gate electrode connected to one of the plurality of scan lines; a third transistor connected between the second node and a third node connected to the j-th receiving line, and including a gate electrode connected to one of the plurality of sensing lines; an energy storage capacitor connected between the first node and the second node; and a light-emitting element including a first electrode connected to the second node and a second electrode connected to the second power source.

[0020] Alternatively, the display panel may further include: a sensing capacitor connected between the fourth node and a ground point to store the voltage applied to the fourth node and to transmit the stored voltage to the sensing unit, wherein the fourth node is connected to the third node via the j-th receiving line.

[0021] Alternatively, the voltage drop sensing unit may sense the voltage drop for the selected at least two pixels based on the voltage transmitted from the sensing capacitor.

[0022] Another aspect of the invention for achieving the stated objective provides a method for driving a display device.

[0023] A method for driving a display device may include: a step of sensing a threshold voltage of a first transistor included in each of the pixels via a receiving line connected to a plurality of pixels; a step of calculating a voltage drop caused by the internal resistance of a plurality of data lines and a plurality of receiving lines connected to each of the pixels; a step of correcting the sensed threshold voltage based on the calculated voltage drop; and a step of generating image data based on the corrected threshold voltage and supplying data signals corresponding to the image data to each of the data lines.

[0024] The step of calculating the voltage drop may include: sensing the voltage drop for at least two pixels selected from each object pixel connected to the j-th (j is a natural number greater than 1) data line and the j-th receive line; using the sensed voltage drop to calculate the voltage drop for each of the object pixels; calculating an offset voltage to compensate for the calculated voltage drop; and adding the offset voltage and the threshold voltage sensed for each of the object pixels to output the result.

[0025] The selected at least two pixels may include: a first pixel disposed on a first horizontal line of the display panel; and a second pixel disposed on a last horizontal line of the display panel.

[0026] The step of sensing voltage drop for the selected at least two pixels may include: supplying a scan signal and a sensing signal to a scan line and a sensing line connected to the first pixel, respectively, and supplying a reference voltage determined based on a threshold voltage sensed for the first pixel to a data line connected to the first pixel.

[0027] Alternatively, the reference voltage may be a voltage obtained by adding the voltage of the first power supply and the threshold voltage sensed by the first transistor for the first pixel.

[0028] It is possible that the voltage drop for the selected at least two pixels includes the voltage drop caused by the internal resistance of the line to which the first power supply is applied.

[0029] The step of calculating the voltage drop for each of the object pixels may include: calculating the maximum voltage drop by differentially dividing the first voltage drop perceived for the first pixel and the second voltage drop perceived for the second pixel.

[0030] The step of calculating the voltage drop for each of the object pixels may include: interpolating the maximum voltage drop based on the number of horizontal lines configured with the plurality of pixels, thereby calculating the voltage drop for each of the object pixels.

[0031] (Invention Effects)

[0032] The display device and driving method of the present invention can sense the voltage drop caused by the wiring resistance of the data line and the receiving line to correct the threshold voltage sensed in each pixel.

[0033] Therefore, the threshold voltage error caused by the wiring resistance of the data line and the receiver line can be reduced, and the performance of external compensation for the threshold voltage of the driving transistors of each pixel can be further improved. Attached Figure Description

[0034] Figure 1 This is a diagram illustrating a display device according to an embodiment of the present invention.

[0035] Figure 2 This is a diagram illustrating the configuration of pixels and sensing units according to an embodiment of the present invention.

[0036] Figure 3 It is used for explanation Figure 2The waveform diagram shows the operation of the driving transistors included in the sensing unit of the sensing pixel during the threshold voltage period.

[0037] Figure 4 It is used in Figure 2 The diagram illustrates the internal resistance of the wiring within the structure of the pixels and sensing units involved.

[0038] Figure 5 It is located at Figure 4 A waveform diagram comparing the node voltages of pixels in the first pixel row and pixels in the last pixel row.

[0039] Figure 6 This is a diagram illustrating the configuration of a sensing unit according to an embodiment of the present invention.

[0040] Figure 7 It is used for explanation Figure 6 An example diagram showing the pixels that sense the voltage drop and the content of the voltage drop in the sensing unit involved.

[0041] Figure 8 It is used for explanation Figure 6 The waveform diagram shows the operation performed by the sensing unit during voltage drop sensing.

[0042] Figure 9 This is a flowchart of a driving method for a display device according to an embodiment of the present invention.

[0043] (Symbol Explanation)

[0044] 100: Display panel; 200: Timing control unit; 300: Scan drive unit; 400: Data drive unit; 500: Power management unit; 600: Sensing unit; 610: Threshold voltage sensing unit; 620: Voltage drop sensing unit; 630: Offset voltage calculation unit; 640: Offset voltage summing unit. Detailed Implementation

[0045] Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily implement them. The present invention can be implemented in various different forms and is not limited to the embodiments described herein.

[0046] To clearly illustrate the invention, irrelevant details have been omitted, and the same or similar reference numerals have been assigned to the same constituent elements throughout the specification. Therefore, the previously described reference numerals may be used in other drawings.

[0047] Furthermore, the sizes and thicknesses of the components shown in the illustrations are arbitrary for ease of explanation, and the present invention is not necessarily limited to the illustrated cases. In the accompanying drawings, the thicknesses are exaggerated to clearly show each layer and region.

[0048] Figure 1 This is a diagram illustrating a display device according to an embodiment of the present invention.

[0049] Reference Figure 1 The display device DD may include a display panel 100, a timing control unit 200, a scan drive unit 300, a data drive unit 400, a power management unit 500, and a sensing unit 600.

[0050] The display panel 100 may include multiple pixels PX[i,j]. The multiple pixels PX[i,j] may be composed of p rows (p is a natural number) and q columns (q is a natural number). Pixels PX[i,j] configured in the same row (hereinafter, horizontal lines may be used interchangeably) may be connected to the same scan line and the same sensing line. Furthermore, pixels PX[i,j] configured in the same column (hereinafter, vertical lines may be used interchangeably) may be connected to the same data line and the same receiving line. For example, a pixel PX[i,j] configured in the i-th row (i is a natural number less than p) and the j-th column (j is a natural number less than q) may be connected to the i-th scan line SL[i] and the i-th sensing line SS[i], and may also be connected to the j-th data line DL[j] and the j-th receiving line RL[j].

[0051] In the display panel 100, the area where pixels PX[i,j] are configured is the display area, and a non-display area without pixels PX[i,j] can be formed on at least one side of the display area. At least a portion of the timing control unit 200, scan drive unit 300, data drive unit 400, sensing unit 600, and power management unit 500 can be configured in the non-display area.

[0052] The timing control unit 200 can generate a scan drive control signal SCS and a data drive control signal DCS corresponding to a synchronization signal supplied from an external source. The scan drive control signal SCS can be supplied to the scan drive unit 300, and the data drive control signal DCS can be supplied to the data drive unit 400. Furthermore, the timing control unit 200 can supply the data drive unit 400 with image data cRGB that has been rearranged based on the input image data RGB supplied from an external source.

[0053] The scan drive control signal SCS can include a start signal and a clock signal. The start signal can be a signal used to control the first moment of the scan signal.

[0054] The data-driven control signal (DCS) can include a source start pulse and a clock signal. The source start pulse controls the start time of data sampling. The clock signal is used to control the sampling operation.

[0055] The scan drive unit 300 can receive the scan drive control signal SCS from the timing control unit 200, and based on the scan drive control signal SCS, sequentially supply scan signals to each scan line SL[1], SL[2], ..., SL[p]. If the scan signals are supplied sequentially, pixels PX[i,j] are selected in units of horizontal lines (or in units of pixel rows), and data signals can be supplied to the selected pixels PX[i,j].

[0056] Furthermore, the scan driving unit 300 can sequentially supply sensing signals to each sensing line SS[1], SS[2], ..., SS[p] based on the scan driving control signal SCS. If the sensing signals are supplied sequentially, pixels PX[i,j] are selected in units of horizontal lines (or in units of pixel rows), and the sensing unit 600 can sense characteristic information of the selected pixels PX[i,j] (e.g., the threshold voltage of the driving transistor of pixel PX[i,j], the mobility of the driving transistor, the degradation of the light-emitting element, etc.).

[0057] The data driving unit 400 can receive the data driving control signal DCS and image data cRGB from the timing control unit 200. The data driving unit 400 can supply data signals to each data line DL[1], DL[2], ..., DL[q] in accordance with the data driving control signal DCS. The data signals supplied to each data line DL[1], DL[2], ..., DL[q] can be supplied to the pixels PX[i,j] arranged on the horizontal line selected by the scan signal. For this purpose, the data driving unit 400 can supply data signals to each data line DL[1], DL[2], ..., DL[q] in a manner synchronized with the scan signal.

[0058] The power management unit 500 can supply the voltage of the first power supply VDD and the voltage of the second power supply VSS to the display panel 100. In addition, the power management unit 500 can supply an initialization voltage based on the initialization power supply Vint. Although not shown, the initialization line for supplying the initialization voltage based on the initialization power supply Vint is connected to each pixel PX[i,j] of the display panel 100.

[0059] The first power supply VDD and the second power supply VSS can generate voltages for driving the light-emitting elements included in each pixel PX[i,j] of the display panel 100. In one embodiment, the voltage of the second power supply VSS can be lower than the voltage of the first power supply VDD. For example, the voltage of the first power supply VDD can be a positive voltage, and the voltage of the second power supply VSS can be a negative voltage.

[0060] The initialization power supply Vint can be used to initialize the power supply of each pixel PX[i,j] included in the display panel 100. For example, the voltage of the initialization power supply Vint can be used to initialize the driving transistors and / or light-emitting elements included in the pixel PX[i,j].

[0061] The sensing unit 600 can sense the threshold voltage Vth (or the change of threshold voltage Vth) of the driving transistor included in each pixel PX[i,j] based on the current or voltage obtained from each receiving line RL[1], RL[2], RL[3], ..., RL[q].

[0062] Furthermore, the sensing unit 600 can sense the voltage drop generated by the internal resistance of each receiving line RL[1], RL[2], RL[3], ..., RL[q] and / or each data line DL[1], DL[2], ..., DL[q], and correct the previously sensed threshold voltage Vth based on the sensed voltage drop. The sensing unit 600 can transmit the threshold voltage Vth' corrected by the voltage drop to the timing control unit 200. Therefore, according to an embodiment of the present invention, by considering the voltage drop of each receiving line RL[1], RL[2], RL[3], ..., RL[q] and / or each data line DL[1], DL[2], ..., DL[q] to correct the threshold voltage Vth sensed once, the threshold voltage Vth of each pixel PX[i,j] can be sensed more accurately.

[0063] In one embodiment, the sensing unit 600 can also sense degradation characteristics such as the mobility of the driving transistors included in each pixel PX[i,j] and / or degradation characteristics (changes in threshold voltage) of the light-emitting elements included in each pixel PX[i,j] based on the current or voltage obtained from each receiving line RL[1], RL[2], RL[3], ..., RL[q].

[0064] The timing control unit 200 can receive image data RGB from the outside, transform the image data RGB based on the threshold voltage Vth' received from the sensing unit 600, and transmit the transformed image data cRGB to the data driving unit 400. That is, the timing control unit 200 can transform the image data RGB based on the threshold voltage Vth' that has been corrected for the voltage drop generated on each receiving line RL[1], RL[2], RL[3], ..., RL[q]. Therefore, the timing control unit 200 can reflect the threshold voltage Vth' for each pixel PX[i,j] in the transformed image data cRGB.

[0065] The data driving unit 400 can supply the data signal of the compensation threshold voltage Vth' (or the change based on the threshold voltage Vth') to each data line DL[1], DL[2], ..., DL[q] based on the image data cRGB received from the timing control unit 200.

[0066] exist Figure 1 The data driving unit 400 is shown on the upper side of the display panel 100 and the sensing unit 600 is shown on the lower side of the display panel 100, but the interpretation is not limited to this. For example, the data driving unit 400 and the sensing unit 600 may be arranged together on the upper side of the display panel 100. Alternatively, the data driving unit 400 and the sensing unit 600 may be arranged together on the lower side of the display panel 100.

[0067] For ease of explanation, the pixel PX[i,j] configured in the i-th row and j-th column can be referred to as pixel PX[i,j], the scan line SL[i] corresponding to the i-th row can be referred to as scan line SL[i], the sensing line SS[i] corresponding to the i-th row can be referred to as sensing line SS[i], the data line DL[j] corresponding to the j-th column can be referred to as data line DL[j], and the receiving line RL[j] corresponding to the j-th column can be referred to as receiving line RL[j].

[0068] Figure 2 This is a diagram illustrating the configuration of pixels and sensing units according to an embodiment of the present invention.

[0069] Reference Figure 2 Pixel PX[i,j] may include a first transistor T1, a second transistor T2, a third transistor T3, an energy storage capacitor Cst, and a light-emitting element EL.

[0070] The first transistor T1 is connected between the first power supply VDD and the second node N2 corresponding to the first electrode of the light-emitting element EL, and includes a gate electrode connected to the first node N1. Throughout this specification, the terms "first transistor T1" and "driving transistor" are used interchangeably.

[0071] The second transistor T2 can be connected between the data line DL[j] and the first node N1, and includes a gate electrode connected to the scan line SL[i]. If a scan signal is supplied through the scan line SL[i], the second transistor T2 can be turned on, and the reference voltage Vref supplied through the data line DL[j] can be transmitted to the first node N1. Here, the reference voltage Vref can be a data signal supplied to the data line DL[j] during the period of the threshold voltage Vth of the sensing drive transistor T1 (e.g., non-display period), and during periods other than the period of the threshold voltage Vth of the sensing drive transistor T1 (e.g., display period), a data signal generated based on the image data cRGB can be supplied from the data driving unit 400 to the data line DL[j].

[0072] The third transistor T3 can be connected between the second node N2 and the third node N3, and includes a gate electrode connected to the sensing line SS[i]. If a sensing signal is supplied through the sensing line SS[i], the third transistor T3 can be turned on, and the second node N2 and the third node N3 can be electrically connected to each other. Furthermore, the third node N3 can be connected to the receiving line RL[j]. Therefore, the voltage Vsen at the second node N2 is transmitted to the sensing unit 600 through the receiving line RL[j], and thus the sensing unit 600 can sense the voltage Vsen applied to the second node N2 (or the voltage applied to the first electrode of the light-emitting element EL). The third transistor T3 can be referred to as the sensing transistor.

[0073] The energy storage capacitor Cst can be connected between the first node N1 and the second node N2. The energy storage capacitor Cst can be charged with the differential voltage between the voltage of the first node N1 and the voltage of the second node N2. For example, the voltage charged to the energy storage capacitor Cst can include the value of the threshold voltage Vth of the driving transistor T1.

[0074] The light-emitting element EL may include a first electrode (or anode) connected to the second node N2 and a second electrode (or cathode) connected to the second power supply VSS. The light-emitting element EL may emit light with a brightness corresponding to the amount of driving current supplied from the first transistor T1.

[0075] On the other hand, a sensing capacitor Csa can be connected between the fourth node N4, which is connected to the third node N3 via the receiving line RL[j], and a reference power supply (e.g., a ground point). When the third transistor T3 is turned on, the sensing capacitor Csa can receive and store the voltage transmitted from the second node N2 to the third node N3 via the receiving line RL[j], and then transmit the stored voltage to the sensing unit 600. The sensing capacitor Csa can be included in the display panel 100. For example, the sensing capacitor Csa can be disposed in a non-display area of ​​the display panel 100. As an example, the sensing capacitor Csa can be disposed in the area between the display area of ​​the display panel 100 and the sensing unit 600.

[0076] In addition, at least one sensing capacitor Csa can be configured on each receiving line RL[j].

[0077] Furthermore, the first transistor T1, the second transistor T2, and the third transistor T3 can be N-type transistors, but those skilled in the art can also modify them into P-type transistors.

[0078] On the other hand, the third node N3 can be connected to the line to which the initialization power supply Vint is applied. In this case, an initialization switch SW_VINT can be connected between the third node N3 and the line to which the initialization power supply Vint is applied. Therefore, if the initialization switch SW_VINT is turned on, an initialization voltage based on the initialization power supply Vint can be supplied to the third node N3. If the third transistor T3 is also turned on, the voltage of the second node N2 can be initialized using the initialization voltage supplied to it. Figure 1 The power management unit 500 in the middle generates the initialization power Vint by outputting its power management unit.

[0079] The sensing unit 600 may include: at least one capacitor C1, C2, which receives and transmits voltage stored in the sensing capacitor Csa according to the capacitance ratio; and an analog-to-digital converter (ADC), which receives the applied voltage stored in the at least one capacitor C1, C2 and converts it into a digital signal for output.

[0080] As a specific example, the sensing unit 600 may include a sensing switch SW_SPL connected between the fourth node N4 and the fifth node N5, at least one capacitor C1, C2, at least one switch SW1, SW2, SW3, and an analog-to-digital converter (ADC).

[0081] At least one capacitor C1, C2 may include at least one of a first capacitor C1 connected between the fifth node N5 and the ground point and a second capacitor C2 connected between the sixth node N6 and the ground point.

[0082] At least one of the following switches SW1, SW2, SW3 may include at least one of the following: a first switch SW1 connected between the fifth node N5 and the sixth node N6; a third switch SW3 connected between the sixth node N6 and the seventh node N7; and a second switch SW2 connected between the sixth node N6 and the ground point.

[0083] If the sensing switch SW_SPL is turned on, the voltage charged in the sensing capacitor Csa can be transferred to the first capacitor C1 based on the ratio between the capacitance of the sensing capacitor Csa and the capacitance of the first capacitor C1.

[0084] If the first switch SW1 is turned on, the voltage that charges the first capacitor C1 can be transferred to the second capacitor C2 based on the capacitance ratio between the first capacitor C1 and the second capacitor C2. If the second switch SW2 is turned on, the second capacitor C2 can be discharged to reset it.

[0085] If the second switch SW2 is open and the third switch SW3 is closed, the voltage stored in the second capacitor C2 can be transferred to the seventh node N7. The analog-to-digital converter (ADC) can convert the voltage applied to the seventh node N7 into a digital signal for output.

[0086] Figure 3 It is used for explanation Figure 2 The waveform diagram shows the operation of the driving transistors included in the sensing unit of the sensing pixel during the threshold voltage period.

[0087] First, during the first period P1, the initialization switch SW_VINT can be in the ON state. Therefore, an initialization voltage Vint_V based on the initialization power supply Vint can be applied to the third node N3, and the initialization voltage Vint_V can be used to initialize the sensing capacitor Csa connected to the third node N3 via the receiving line RL[j].

[0088] During the second period P2, as a scan signal (which can be a high-level voltage) is supplied through scan line SL[i], the second transistor T2 is turned on. At this time, through the conduction of the second transistor T2, a reference voltage Vref is supplied to the gate electrode of the first transistor T1 via data line DL[j]. Furthermore, as a sensing signal is supplied via sensing line SS[i], the third transistor T3 is turned on, and the initialization voltage Vint_V applied to the third node N3 can be passed to the second node N2.

[0089] That is, during the second period P2, a reference voltage Vref is applied to the gate electrode (or the first node N1) of the first transistor T1, and an initialization voltage Vint_V is applied to the second electrode (or the second node N2) of the first transistor T1.

[0090] During the third period P3, as the sensing switch SW_SPL is turned on, an initialization voltage Vint_V based on the initialization power supply Vint can be supplied to the sensing unit 600. Therefore, at least one capacitor (e.g., the first capacitor C1) included in the sensing unit 600 can be initialized using the initialization voltage Vint_V.

[0091] During the fourth period P4, as the initialization switch SW_VINT is turned off and the second transistor T2 remains on, the voltage Vsen of the second node N2 (or the second electrode of the first transistor T1) can rise to the differential voltage Vref-Vth between the reference voltage Vref and the threshold voltage Vth of the first transistor T1. The reference voltage Vref used to sense the threshold voltage Vth can be less than the voltage of the first power supply VDD. Therefore, if the voltage Vsen of the second node N2 rises to the differential voltage Vref-Vth, the first transistor T1 is turned off, so the voltage Vsen of the second node N2 will not rise further. At this time, the differential voltage Vref-Vth applied to the second node N2 can be transmitted to the third node N3 through the third transistor T3, and the differential voltage Vref-Vth transmitted to the third node N3 can be transmitted to the sensing capacitor Csa through the receiving line RL[j]. That is, the sensing capacitor Csa can be charged using the differential voltage Vref-Vth. The differential voltage Vref-Vth charged to the sensing capacitor Csa is transmitted to the sensing unit 600 through the sensing switch SW_SPL, which is in the ON state. The sensing unit 600 can obtain the threshold voltage Vth from the differential voltage Vref-Vth. That is, the fourth period P4 may include the moment Tsampling when sensing the threshold voltage.

[0092] For example, the sensing unit 600 can receive the transmission of the differential voltage Vref-Vth charged to the sensing capacitor Csa based on the capacitance ratio between the sensing capacitor Csa and at least one capacitor C1, C2 included in the sensing unit 600, and remove the component corresponding to the reference voltage Vref from the received differential voltage Vref-Vth, thereby sensing the threshold voltage Vth or the amount of change of the threshold voltage Vth of the first transistor T1.

[0093] Figure 4 It is used in Figure 2 The diagram illustrates the internal resistance of the wiring within the structure of the pixels and sensing units involved. Figure 5 It is located at Figure 4 A waveform diagram comparing the node voltages of pixels in the first pixel row and pixels in the last pixel row.

[0094] exist Figure 4The diagram shows the internal wiring resistance that affects the perception of the threshold voltage Vth in pixels PX[1,j] in the first pixel row and pixels PX[p,j] in the last pixel row, among the pixels located in the j-th column.

[0095] Reference Figure 4 The third node N3 and the fourth node N4 are connected to each other via the receiving line RL[j]. Therefore, at the moment of sensing the threshold voltage Vth, Tsampling, the differential voltage Vref-Vth applied to the third node N3 will be transferred to the fourth node N4. However, the voltage of the third node N3 will be transferred to the fourth node N4 by an amount corresponding to the voltage drop caused by the internal resistance Rs of the receiving line RL[j] connecting the third node N3 and the fourth node N4.

[0096] Furthermore, the reference voltage Vref supplied through the data line DL[j] may be reduced by an amount corresponding to the voltage drop VRd caused by the internal resistance Rd of the data line DL[j] and thus transferred to the first electrode of the second transistor T2.

[0097] In addition, the voltage of the first power supply VDD may also be reduced by an amount corresponding to the voltage drop VRe caused by the internal resistance Re of the line to which the first power supply VDD is applied, and thus transferred to the first electrode of the first transistor T1.

[0098] As described above, the larger the internal resistances Rs, Rd, and Re of the receiving line RL[j], the data line DL[j], and the line to which the first power supply VDD is applied, the larger the voltage drop generated in each line. Therefore, there is a problem that the threshold voltage Vth of the first transistor T1 sensed by the sensing unit 600 will vary by a amount corresponding to the voltage drop. In particular, for pixels PX[i,j], the relative wiring length from the data driving unit 400 or the sensing unit 600 varies depending on their position in the display panel 100, so the amount of variation in the threshold voltage Vth caused by the voltage drop may also be different for each pixel PX[i,j]'s configuration position.

[0099] For example, such as Figure 4As shown, when the data driving unit 400 and / or the sensing unit 600 are disposed on the upper side of the display panel 100, the data driving unit 400 is adjacent to the pixel PX[1,j] located in the first pixel row, so the wiring length of the data line DL[j] connecting the two is short. Furthermore, the sensing unit 600 is also adjacent to the pixel PX[1,j] located in the first pixel row, so the wiring length of the receiving line RL[j] connecting the two is also short. Therefore, when sensing the threshold voltage Vth for the pixel PX[1,j] located in the first pixel row, the internal resistance Rd of the data line DL[j] and / or the internal resistance Rs of the receiving line RL[j] are so small as to be negligible. Therefore, for the threshold voltage Vth sensed in the pixel PX[1,j] located in the first pixel row, the voltage drop caused by the internal wiring resistances (Rd, Rs) can be ignored.

[0100] However, the data driving unit 400 is furthest from the pixel PX[p,j] located in the last p-th pixel row, therefore the wiring length of the data line DL[j] connecting the two is also the longest. Furthermore, the sensing unit 600 is also furthest from the pixel PX[p,j] located in the last p-th pixel row, therefore the wiring length of the receiving line RL[j] connecting the two is also the longest. Therefore, when sensing the threshold voltage Vth for the pixel PX[p,j] located in the last p-th pixel row, the internal resistance Rd of the data line DL[j] and / or the internal resistance Rs of the receiving line RL[j] may be quite large. Therefore, the threshold voltage Vth sensed in the pixel PX[p,j] located in the last p-th pixel row may include a voltage drop caused by a non-negligible internal wiring resistance (Rd, Rs).

[0101] As mentioned above, for pixels PX[1,j] located in the first pixel row closest to the data driving unit 400 and the sensing unit 600, the internal resistance Rd of the data line DL[j] and / or the internal resistance Rs of the receiving line RL[j] can be ignored. Therefore, referring to Figure 4 and Figure 5 At the moment of sensing the threshold voltage Vth, Tsampling applies a voltage to the third node N3 of the pixel PX[1,j] in the first pixel row. This voltage is the differential voltage Vref-Vth between the reference voltage Vref and the threshold voltage Vth. This differential voltage Vref-Vth is stored after the sensing capacitor Csa and will be passed to the fourth node N4 as is.

[0102] However, for pixel PX[p, j] located in the last p-th pixel row, there is a voltage drop VRd caused by the internal resistance Rd of the data line DL[j]. Therefore, referring to Figure 4 and Figure 5At the moment of sensing the threshold voltage Vth, Tsampling, a voltage Vref-VRd is applied to the gate electrode of the first transistor T1, which is a reduction of the reference voltage Vref by an amount corresponding to the voltage drop VRd of the data line DL[j]. Furthermore, a voltage Vref-Vth-VRd is applied to the second node N2, which is a reduction of the voltage drop VRd of the data line DL[j] and the threshold voltage Vth by the reference voltage Vref. Additionally, the voltage Vref-Vth-VRd of the second node N2 is passed to the third node N3, and the voltage Vref-Vth-VRd-VRs, which is a reduction of the voltage drop VRs caused by the internal resistance Rs of the receiving line RL[j], is passed to the sensing capacitor Csa. Therefore, the voltage passed to the sensing capacitor Csa can be Vref-Vth-Vdrop, which is a reduction of the threshold voltage Vth and the voltage drop Vdrop (=VRd+VRs) of the data line DL[j] and the receiving line RL[j] by the reference voltage Vref.

[0103] In summary, the threshold voltage Vth sensed by the sensing unit 600 can vary according to the voltage drop Vdrop (=VRd+VRs) between the data line DL[j] and the receiving line RL[j], so it is necessary to correct for the voltage drop Vdrop.

[0104] Therefore, in one embodiment of the present invention, a scheme is provided in which the threshold voltage Vth of each pixel is sensed and the sensed threshold voltage Vth is corrected (or changed) based on the voltage drop Vdrop (=VRd+VRs) of the data line DL[j] and the receiving line RL[j], thereby enabling a more accurate sense of the threshold voltage Vth.

[0105] Figure 6 This is a diagram illustrating the configuration of a sensing unit according to an embodiment of the present invention.

[0106] Reference Figure 6 An embodiment of the present invention relates to a sensing unit 600, which may include a threshold voltage sensing unit 610, a voltage drop sensing unit 620, an offset voltage calculation unit 630, and an offset voltage summing unit 640.

[0107] The threshold voltage sensing unit 610 can sense the threshold voltage Vth of the driving transistor T1 included in the pixel. That is, in situations such as... Figure 2 In the circuit configuration, the data driving unit 400 and the scan driving unit 300 perform operations related to... Figure 3 The threshold voltage sensing unit 610 can sense the differential voltage Vref-Vth stored in the sensing capacitor Csa during the operation corresponding to Tsampling during the threshold voltage sensing period. Figure 2The voltage of the fourth node N4 is used to obtain the differential voltage Vref-Vth stored in the sensing capacitor Csa, and the threshold voltage Vth of each pixel is obtained from the differential voltage Vref-Vth for output.

[0108] The voltage drop sensing unit 620 can sense each object pixel (e.g., connected to the j-th (j is a natural number greater than 1) data line DL[j] and the j-th receive line RL[j]) Figure 4 Perception of at least two pixels (e.g., PX[1,j], ..., PX[p,j]) within PX[1,j], ..., PX[p,j] Figure 4 The voltage drop of PX[1,j] and PX[p,j] is calculated, and the voltage drop Vdrop for each of the object pixels is calculated using the sensed voltage drop.

[0109] For example, in such Figure 2 In the circuit configuration, the data driving unit 400 and the scan driving unit 300 perform the functions described later. Figure 7 The operation during voltage drop sensing allows the voltage VDD-Vdrop, including the voltage drop Vdrop, to be stored in the sensing capacitor Csa. The voltage drop sensing unit 620 can sense... Figure 2 The voltage at the fourth node N4 is used to obtain the voltage VDD-Vdrop stored in the sensing capacitor Csa, and the voltage drop Vdrop can be sensed from the obtained voltage VDD-Vdrop.

[0110] For example, the voltage drop sensing unit 620 can be based on... Figure 2 The voltage transmitted by the sensing capacitor Csa is used to sense the voltage drop for the at least two pixels.

[0111] The offset voltage calculation unit 630 can calculate the offset voltage Vdrop_offset for each object pixel to compensate for the calculated voltage drop.

[0112] The offset voltage adder 640 can add the offset voltage Vdrop_offset and the threshold voltage Vth sensed for each object pixel to output the corrected threshold voltage Vth'. For example, the offset voltage adder 640 can be implemented as an adder of various forms.

[0113] The threshold voltage sensing unit 610 and the voltage drop sensing unit 620 can be based on Figure 2 The circuit configuration of the sensing unit 600 shown senses the voltage (or the voltage of the fourth node N4) stored in the sensing capacitor Csa, and can sense the voltage drop or threshold voltage from the sensed voltage.

[0114] The operation of each component is explained in detail below.

[0115] Figure 7 It is used for explanation Figure 6 An example diagram showing the pixels that sense the voltage drop and the content of the voltage drop in the sensing unit involved. Figure 8 It is used for explanation Figure 6 The waveform diagram shows the operation performed by the sensing unit during voltage drop sensing.

[0116] For ease of explanation, the operation of the sensing unit 600 will be described below by referring to the multiple pixels connected to the j-th data line DL[j] and the j-th receiving line RL[j] (i.e., pixels arranged on the same vertical line) as object pixels.

[0117] In one embodiment of the invention, in order to sense the voltage drop in each pixel caused by the internal resistance Rd of the data line DL[j] and the internal resistance Rs of the receiver line RL[j], a voltage based on the first power supply VDD can be used.

[0118] As before Figure 4 As explained, one of the first pixel PX[1,j] configured on the first horizontal line and the second pixel PX[p,j] configured on the last p-th horizontal line can have its wiring internal resistance (Rd, Rs) ignored because it is adjacent to the data driving unit 400 and the sensing unit 600, while the remaining pixel can have its wiring internal resistance (Rd, Rs) maximized.

[0119] Therefore, the voltage drop sensing unit 620 can sense the voltage drop for the first pixel PX[1,j] configured on the first horizontal line and the second pixel PX[p,j] configured on the last p horizontal line among the object pixels connected to the j-th data line DL[j] and the j-th receiving line RL[j], and use the sensed voltage drop to calculate the voltage drop for each object pixel.

[0120] Reference Figure 7 and Figure 8 This describes the operation of perceptual pressure drop with the first pixel PX[1,j] as the object.

[0121] First, at the first moment TP1, the scan drive unit 300 can supply scan signals and sensing signals to the scan line SL[1] and sensing line SS[1] connected to the first pixel PX[1,j], respectively, and the data drive unit 400 can supply reference voltage Vref to the data line DL[j] connected to the first pixel PX[1,j].

[0122] At this time, the voltage of the first power supply VDD can be reduced by an amount corresponding to the voltage drop VRe caused by the internal resistance Re of the line to which the first power supply VDD is applied and applied to the first electrode of the first transistor T1.

[0123] Here, the reference voltage Vref can be different from... Figure 3During the sensing period of the threshold voltage Vth involved, it can be the voltage VDD+Vth obtained by adding the voltage of the first power supply VDD and the threshold voltage Vth sensed by the first transistor T1 for the first pixel PX[1,j]. Therefore, according to the reference voltage Vref, the first transistor T1 remains in the on state until the first electrode and the second electrode of the first transistor T1 become the same voltage, so the voltage VDD-VRe applied to the first electrode of the first transistor T1 can be applied to the second node N2 as is.

[0124] At the second moment TP2, the sensing switch SW_SPL is turned on, and at least one capacitor included in the sensing unit 600 can be initialized using the initialization voltage of the initialization power supply.

[0125] At the third moment TP3, the initialization switch SW_VINT is turned off, so the voltage VDD-VRe applied to the second node N2 at the first moment TP1 can be passed to the third node N3. Furthermore, the internal resistance Rs of the receiving line RL[j] can be ignored for the first pixel PX[1,j], so the voltage passed to the third node N3 can be applied to the fourth node N4 connected to the sensing capacitor Csa as is.

[0126] Therefore, the voltage sensed by the sensing capacitor Csa by the sensing unit 600 can be a voltage VDD-VRe that is a reduction of the voltage of the first power supply VDD by an amount corresponding to the voltage drop VRe caused by the internal resistance Re of the line to which the first power supply VDD is applied. The voltage drop Vdrop for the first pixel PX[1,j] can be equal to the voltage drop VRe caused by the internal resistance Re of the line to which the first power supply VDD is applied.

[0127] Similar to the operation of sensing voltage drop with the first pixel PX[1,j] as the object, voltage drop can also be sensed with the second pixel PX[p,j]. In the second pixel PX[p,j], the internal resistance Re of the line to which the first power supply VDD is applied can be the same as that of the first pixel PX[1,j]. For example, if the first power supply VDD is supplied to both sides of the display panel 100 (specifically the upper and lower parts), it can be assumed that the internal resistance Re of the line to which the first power supply VDD is applied is the same. However, in the second pixel PX[p,j], a voltage drop VRs of the receiving line RL[j] will be further generated. Therefore, the voltage transmitted to the fourth node N4 can be the voltage VDD minus the voltage drop VRe caused by the internal resistance Re of the line to which the first power supply VDD is applied and the voltage drop VRs of the receiving line RL[j], which is VDD-VRe-VRs. That is, the voltage drop Vdrop for the second pixel PX[p,j] can be the voltage VRe+VRs obtained by adding the voltage drop VRe caused by the internal resistance Re of the line to which the first power supply VDD is applied and the voltage drop VRs of the receiving line RL[j].

[0128] As described above, the voltage drops for the first pixel PX[1,j] and the second pixel PX[p,j] each include the voltage drop VRe caused by the internal resistance Re of the line to which the first power supply VDD is applied. Therefore, the voltage drop sensing unit 620 can calculate the maximum voltage drop VRs by subtracting the voltage drop VRe sensed for the first pixel PX[1,j] and the voltage drop VRe+VRs sensed for the second pixel PX[p,j].

[0129] like Figure 7 As shown, assuming the data driving unit 400 and the sensing unit 600 are arranged on one side of the upper part of the display panel 100, the second pixel PX[p,j] is arranged on the horizontal line furthest from the data driving unit 400 and the sensing unit 600. Therefore, the voltage drop VRs of the receiving line RL[j] connected to the second pixel PX[p,j] can be the maximum voltage drop VRs among the voltage drops for each target pixel.

[0130] The voltage drop sensing unit 620 can calculate the voltage drop for each object pixel by interpolating the maximum voltage drop based on the number of horizontal lines configured for each pixel. For example, the number of horizontal lines involved in UHD (Ultra High Definition) resolution is 2160, so if the maximum voltage drop VRs is divided into the number of horizontal lines, it can be converted into the voltage drop for each object pixel.

[0131] On the other hand, such as in Figure 7The maximum voltage drop VRs that can be confirmed in the involved paths only includes the voltage drop VRs caused by the internal resistance Rs of the receiving line RL[j], and does not include the voltage drop VRd caused by the internal resistance Rd of the data line DL[j].

[0132] However, when the data line DL[j] and the receiving line RL[j] are manufactured with the same wiring configuration through the same process, and the data driving unit 400 and the sensing unit 600 are arranged together on one side of the upper part or one side of the lower part of the display panel 100, the voltage drop VRd caused by the internal resistance Rd of the data line DL[j] and the voltage drop VRs caused by the internal resistance Rs of the receiving line RL[j] can be similar or the same. Therefore, the voltage drop sensing unit 620 according to an embodiment of the present invention calculates a value corresponding to twice the previously calculated maximum voltage drop VRs, thereby calculating the maximum voltage drop that reflects both the voltage drop VRs of the receiving line RL[j] and the voltage drop VRd of the data line DL[j].

[0133] As another example, instead of the method of multiplying the maximum voltage drop VRs by 2 by the voltage drop sensing unit 620, the offset voltage calculation unit 630 can also generate an offset voltage Vdrop_offset corresponding to twice the maximum voltage drop VRs.

[0134] Therefore, the sensing unit 600 of the present invention can sense the voltage drop Vdrop (=VRd+VRs) of the data line DL[j] and the receiving line RL[j], and correct the threshold voltage Vth of each pixel PX[i,j] accordingly with the amount of the sensed voltage drop Vdrop, thereby outputting the corrected threshold voltage Vth'.

[0135] Figure 9 This is a flowchart of a driving method for a display device according to an embodiment of the present invention.

[0136] Reference Figure 9 The driving method of the display device may include: step S100 of sensing the threshold voltage of the first transistor included in each pixel through each receiving line connected to a plurality of pixels; step S110 of calculating the voltage drop caused by the internal resistance of each data line and each receiving line connected to each pixel; step S120 of correcting the threshold voltage based on the calculated voltage drop; and step S130 of generating image data based on the corrected threshold voltage and supplying a data signal corresponding to the image data to each data line.

[0137] Step S110, which calculates the voltage drop, may include: sensing the voltage drop for at least two pixels among the object pixels connected to the j-th (j is a natural number greater than 1) data line and the j-th receive line; calculating the voltage drop for each of the object pixels using the sensed voltage drop; calculating an offset voltage to compensate for the voltage drop; and adding the offset voltage and the threshold voltage sensed for each of the object pixels and outputting the result.

[0138] The at least two pixels may include a first pixel disposed on a first horizontal line of the display panel and a second pixel disposed on a last horizontal line of the display panel.

[0139] The step of sensing the voltage drop for the at least two pixels may include the following steps: supplying a scan signal and a sensing signal to a scan line and a sensing line connected to the first pixel, respectively, and supplying a reference voltage determined based on a threshold voltage sensed for the first pixel to a data line connected to the first pixel.

[0140] The reference voltage may be a voltage obtained by adding the voltage of the first power supply and the threshold voltage sensed by the first transistor for the first pixel.

[0141] The voltage drop across the at least two pixels may include the voltage drop caused by the internal resistance of the line to which the first power supply is applied.

[0142] The step of calculating the voltage drop for each of the object pixels may include the step of calculating the maximum voltage drop by differentiating the first voltage drop perceived for the first pixel and the second voltage drop perceived for the second pixel.

[0143] The step of calculating the voltage drop for each of the object pixels may include interpolating the maximum voltage drop based on the number of horizontal lines configured for each of the object pixels, thereby calculating the voltage drop for each of the object pixels.

[0144] Here, the display device can be interpreted as Figures 1 to 9 The display device involved is DD. Furthermore, the driving method for the display device may include... Figures 1 to 8 The structure and operation method of the display device DD are described in the text.

[0145] Up to this point, the accompanying drawings and detailed descriptions of the invention have been provided merely as illustrative purposes and are not intended to limit or restrict the scope of the invention as defined in the claims. Therefore, those skilled in the art will understand that various modifications and equivalent embodiments can be achieved. Consequently, the true scope of protection of this invention should be determined by the technical concept outlined in the claims.

Claims

1. A display device, comprising: The display panel includes multiple pixels; The scanning drive unit supplies scanning signals to a plurality of scanning lines connected to each of the pixels and sensing signals to a plurality of sensing lines connected to each of the pixels; The data driving unit supplies data signals corresponding to image data to multiple data lines connected to each pixel; The sensing unit senses the threshold voltage of the first transistor included in each pixel through each receiving line connected to each pixel, and corrects the sensed threshold voltage based on the voltage drop caused by the internal resistance of the data line and the internal resistance of the receiving line. as well as The timing control unit generates the image data by modifying the input image data based on the corrected threshold voltage. The sensing unit includes: The voltage drop sensing unit selects at least two pixels from the plurality of pixels that are connected to the j-th data line and the j-th receive line as objects, senses the voltage drop, and uses the sensed voltage drop to calculate the voltage drop for each of the object pixels, where j is a natural number greater than or equal to 1. The selected at least two pixels include: The first pixel is disposed on the first horizontal line of the display panel; and The second pixel is positioned at the last horizontal line of the display panel; The voltage drop sensing unit calculates the maximum voltage drop by subtracting the first voltage drop sensed for the first pixel and the second voltage drop sensed for the second pixel.

2. The display device according to claim 1, wherein, The sensing unit includes: The threshold voltage sensing unit senses the threshold voltage of the first transistor; The offset voltage calculation unit calculates the offset voltage to compensate for the voltage drop; and The offset voltage summing unit adds the threshold voltage perceived by the target pixel to the offset voltage and outputs the result.

3. The display device according to claim 2, wherein, The sensing unit and the data driving unit are together disposed on one side of the display panel.

4. The display device according to claim 2, wherein, The scanning drive unit supplies scanning signals and sensing signals to the scanning line and sensing line connected to the first pixel, respectively. The data driving unit supplies a reference voltage, determined based on a threshold voltage sensed for the first pixel, to the data line connected to the first pixel.

5. The display device according to claim 4, wherein, The reference voltage is obtained by adding the voltage of the first power supply and the threshold voltage sensed by the first transistor for the first pixel.

6. The display device according to claim 1, wherein, The voltage drop sensing unit interpolates the maximum voltage drop based on the number of horizontal lines configured for each pixel, thereby calculating the voltage drop for each object pixel.

7. The display device according to claim 2, wherein, The object pixels include: The first transistor is connected between a first power source and a second node, and includes a gate electrode connected to the first node; A second transistor is connected between the j-th data line and the first node, and includes a gate electrode connected to one of the plurality of scan lines; A third transistor is connected between the second node and a third node connected to the j-th receiving line, and includes a gate electrode connected to one of the plurality of sensing lines; An energy storage capacitor is connected between the first node and the second node; and The light-emitting element includes a first electrode connected to the second node and a second electrode connected to a second power source.

8. The display device according to claim 7, wherein, The display panel further includes: a sensing capacitor connected between the fourth node and a ground point to store the voltage applied to the fourth node and to transmit the stored voltage to the sensing unit, wherein the fourth node is connected to the third node through the j-th receiving line.

9. The display device according to claim 8, wherein, The voltage drop sensing unit senses the voltage drop for the selected at least two pixels based on the voltage transmitted from the sensing capacitor.

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