Display device

Abstract

The disclosure relates to a display apparatus. The display apparatus includes a first pixel including a first organic light emitting diode, an initialization voltage generator for generating a first initialization voltage to be supplied to an anode of the first organic light emitting diode, and a timing controller including a first lookup table in which a plurality of first initialization voltage values corresponding to a plurality of maximum luminances are recorded, the timing controller being configured to determine a value of the first initialization voltage based on reception information related to a target maximum luminance and the first lookup table.

Description

[0001] This application is a divisional application of the invention filed on October 11, 2018, with application number 201811182498.2 and entitled "Display Device and Driving Method Thereof".

[0002] Cross-referencing related applications

[0003] This application claims priority and benefit to Korean Patent Application No. 10-2017-0144924, filed with the Korean Intellectual Property Office on November 1, 2017, the entire disclosure of which is incorporated herein by reference. Technical Field

[0004] Some aspects of exemplary embodiments of this disclosure relate to display devices and driving methods thereof. Background Technology

[0005] With the development of information technology, the importance of display devices as the connection medium between users and information has increased. Therefore, display devices such as liquid crystal displays, organic light-emitting diode displays, and plasma display panels are being used more and more frequently.

[0006] Among these display devices, organic light-emitting diodes (OLEDs) use organic light-emitting diodes (OLEDs) to display images, which generate light through the recombination of electrons and holes. OLEDs have a relatively high response time and are driven with relatively low power consumption.

[0007] Organic light-emitting display devices display target images to users by writing data voltages representing target grayscale into each pixel and allowing multiple organic light-emitting diodes to emit light corresponding to the data voltages.

[0008] Typically, multiple organic light-emitting diodes (OLEDs) are configured, including red, blue, and green OLEDs. Because the organic materials in OLEDs have different band gaps, multiple OLEDs emit light of different wavelengths.

[0009] The amount of driving current supplied to organic light-emitting diodes (OLEDs) of multiple colors can be set differently depending on the emission efficiency of the organic material. For example, a relatively small driving current can be supplied to OLEDs of colors with organic materials that have high emission efficiency.

[0010] However, under low-brightness conditions where the driving current is very small, it may be necessary to charge the capacitor of the corresponding organic light-emitting diode for a relatively long period of time, and therefore, color dragging may occur where the corresponding organic light-emitting diode emits light later than other organic light-emitting diodes of different colors.

[0011] The information disclosed in this background section is only intended to enhance the understanding of the background art, and therefore, the information may include information that does not constitute prior art. Summary of the Invention

[0012] Some example embodiments include a display device and a driving method for the display device that can eliminate or mitigate color drag by controlling the initialization voltage according to brightness conditions.

[0013] According to some example embodiments of the present disclosure, a display device includes: a first pixel including a first organic light-emitting diode; an initialization voltage generator configured to generate a first initialization voltage to be supplied to the anode of the first organic light-emitting diode; and a timing controller including a first lookup table recording a plurality of first initialization voltage values ​​corresponding to a plurality of maximum brightness, the timing controller being configured to determine the value of the first initialization voltage based on received information related to a target maximum brightness and the first lookup table.

[0014] Multiple first initial voltage values ​​can be obtained by adding a first offset value to the value of the first power voltage to be supplied to the cathode of the first organic light-emitting diode.

[0015] Each of the first offset values ​​can be inversely proportional to the magnitude of the corresponding maximum brightness.

[0016] Multiple maximum brightness levels can include a reference maximum brightness level. The first offset value at the reference maximum brightness level can be 0.

[0017] The first offset value corresponding to the first maximum brightness group that exceeds the reference maximum brightness among a plurality of maximum brightness can be less than 0.

[0018] The first offset value corresponding to the second maximum brightness group, which is less than the reference maximum brightness among a plurality of maximum brightness groups, can be greater than 0.

[0019] The first electrical voltage can be inversely proportional to the magnitude of the target's maximum brightness.

[0020] The first power voltage can have a specific voltage value when the target maximum brightness corresponds to the reference maximum brightness, and a voltage value lower than the specific voltage value when the target maximum brightness corresponds to the first maximum brightness group.

[0021] The first power voltage can have a voltage value equal to or greater than a specific voltage value when the target maximum brightness corresponds to the second maximum brightness group.

[0022] Regardless of the target's maximum brightness, the second electrical voltage supplied to the anode of the first organic light-emitting diode can have a fixed value.

[0023] The display device may further include a second pixel, the second pixel including a second organic light-emitting diode (OLED), the second OLED having an organic material with a band gap different from that of the organic material of the first OLED. The timing controller may further include a second lookup table recording a plurality of second initialization voltage values ​​corresponding to a plurality of maximum brightness values, and the timing controller may be configured to determine the value of the second initialization voltage based on received information related to a target maximum brightness and the second lookup table. An initialization voltage generator may be configured to generate a second initialization voltage to be supplied to the anode of the second OLED.

[0024] Multiple first initialization voltage values ​​can be obtained by adding a first offset value to the value of a first power voltage to be supplied to the cathode of a first organic light-emitting diode, and multiple second initialization voltage values ​​can be obtained by adding a second offset value to the value of a first power voltage to be supplied to the cathode of a second organic light-emitting diode.

[0025] Multiple maximum brightness levels can include a reference maximum brightness level. The first and second offset values ​​at the reference maximum brightness level can be 0.

[0026] The first offset value corresponding to the first maximum brightness group that exceeds the reference maximum brightness among a plurality of maximum brightness can be less than 0, and the second offset value corresponding to the first maximum brightness group can be less than the first offset value.

[0027] The first offset value corresponding to the second maximum brightness group, which is less than the reference maximum brightness among a plurality of maximum brightness groups, can be greater than 0, and the second offset value corresponding to the second maximum brightness group can be less than the first offset value.

[0028] The first power voltage may have a specific voltage value when the target maximum brightness corresponds to the reference maximum brightness, and the first power voltage may have a voltage value lower than the specific voltage value when the target maximum brightness corresponds to the first maximum brightness group.

[0029] The first power voltage can have a voltage value equal to or greater than a specific voltage value when the target maximum brightness corresponds to the second maximum brightness group.

[0030] Regardless of the target's maximum brightness, the second electrical voltage supplied to the anode of the first organic light-emitting diode and the anode of the second organic light-emitting diode can have a fixed value.

[0031] According to an aspect of this disclosure, a method for driving a display device is provided, the method comprising: receiving information relating to a target maximum brightness via a timing controller; determining, via the timing controller, a value of a first initialization voltage corresponding to the target maximum brightness using a first lookup table constructed in the timing controller; initializing an amount of charge accumulated in the first organic light-emitting diode by supplying the first initialization voltage to the anode of the first organic light-emitting diode of the first pixel via an initialization voltage generator; and allowing the first organic light-emitting diode to emit light corresponding to a target grayscale having a brightness equal to or less than the target maximum brightness.

[0032] Multiple first initial voltage values ​​corresponding to multiple maximum brightness values ​​can be recorded in a first lookup table. These multiple first initial voltage values ​​can be obtained by adding a first offset value to the value of the first power voltage to be supplied to the cathode of the first organic light-emitting diode. Attached Figure Description

[0033] Some aspects of exemplary embodiments will now be described more fully with reference to the accompanying drawings; however, these embodiments may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be exhaustive and comprehensive, and will fully convey the scope of the exemplary embodiments to those skilled in the art.

[0034] In the accompanying drawings, dimensions may be exaggerated for clarity. It will be understood that when an element is referred to as "located between two elements," the element can be the only element between those two elements, or there may be one or more intermediate elements. Throughout the text, the same reference numerals refer to the same elements.

[0035] Figure 1 This is a diagram illustrating a display device according to some exemplary embodiments of the present invention.

[0036] Figure 2 This is a diagram illustrating the first pixel according to some exemplary embodiments of the present invention.

[0037] Figure 3 This is a diagram illustrating the first initialization voltage when the target maximum brightness is equal to the reference maximum brightness, according to some exemplary embodiments of the present invention.

[0038] Figure 4 This is a diagram illustrating the first initialization voltage when the target maximum brightness is greater than the reference maximum brightness, according to some exemplary embodiments of the present invention.

[0039] Figure 5 This is a diagram illustrating the first initialization voltage when the target maximum brightness is less than the reference maximum brightness, according to some exemplary embodiments of the present invention.

[0040] Figure 6 This is a diagram illustrating examples of a first initialization voltage, a first power voltage, and a second power voltage based on a target maximum brightness according to some exemplary embodiments of the present invention.

[0041] Figure 7 This is a diagram illustrating a display device according to some exemplary embodiments of the present invention.

[0042] Figure 8 This is a diagram illustrating an embodiment of a pixel unit according to some exemplary embodiments of the present invention.

[0043] Figure 9 This is a diagram illustrating another embodiment of a pixel unit according to some exemplary embodiments of the present invention.

[0044] Figure 10 This is a diagram illustrating the color dragging phenomenon.

[0045] Figure 11 This is a diagram illustrating the first and second pixels according to some exemplary embodiments of the present invention.

[0046] Figure 12 This is a diagram illustrating a first initialization voltage and a second initialization voltage when the target maximum brightness is equal to the reference maximum brightness, according to some exemplary embodiments of the present invention.

[0047] Figure 13 This is a diagram illustrating a first initialization voltage and a second initialization voltage when the target maximum brightness is greater than a reference maximum brightness, according to some exemplary embodiments of the present invention.

[0048] Figure 14 This is a diagram illustrating a first initialization voltage and a second initialization voltage when the target maximum brightness is less than the reference maximum brightness, according to some exemplary embodiments of the present invention. Detailed Implementation

[0049] In the following description, aspects of some exemplary embodiments are described in more detail with reference to the accompanying drawings, enabling those skilled in the art to readily practice this disclosure. This disclosure may be implemented in various different forms and is not limited to the exemplary embodiments described herein.

[0050] To clearly describe this disclosure, certain irrelevant or repetitive descriptions may be omitted, and throughout the specification, the same or similar reference numerals are used to designate the same or similar components. Therefore, the same reference numerals may be used in different figures to identify the same or similar elements.

[0051] Furthermore, for better understanding and ease of description, the dimensions and thicknesses of each component illustrated in the accompanying drawings are arbitrarily shown, but this disclosure is not limited thereto. For clarity, the thicknesses of certain parts and regions have been exaggerated.

[0052] Figure 1 This is a diagram illustrating a display device according to some exemplary embodiments of the present invention.

[0053] refer to Figure 1 A display device according to some exemplary embodiments of the present invention includes a processor 9, a driver IC 10, a scan driver 20, an emission control driver 30, a pixel unit 40, and a DC-DC converter 50. The driver IC 10 may include a timing controller 11, an initialization voltage generator 12, and a data driver 13.

[0054] Processor 9 can be a general-purpose processing device. For example, processor 9 can be an application processor (AP) of a mobile phone. As another example, processor 9 can be a host system.

[0055] The processor 9 can supply the control signals and image signals required for displaying the image to the driver IC 10. For example, the control signals may include data enable signals, vertical synchronization signals, horizontal synchronization signals, target maximum brightness, etc.

[0056] The target maximum brightness can be the brightness at the maximum grayscale value to be displayed on the current display device. When defining the grayscale of a pixel in an image signal for a frame as unit image data, the unit image data can, for example, have 8 bits. With 8 bits, 256 grayscale values ​​can be represented. The minimum grayscale (grayscale 0) can be the darkest, and the maximum grayscale (grayscale 255) can be the brightest. In this case, the brightness can be defined as the target maximum brightness when all pixels in pixel unit 40 emit light with the maximum grayscale value.

[0057] According to some exemplary embodiments of the present invention, the unit of the target maximum brightness is specified as nit. That is, pixel unit 40 can display partially (spatially) dark and bright images based on the image signal, or display dark and bright images based on frames (time). However, the maximum brightness of the image is limited by the target maximum brightness.

[0058] The target maximum brightness can be set manually when the user operates the display device, or automatically using algorithms linked to the illuminance sensor.

[0059] The timing controller 11 converts the control signals and image signals supplied from the processor 9 to suit the specifications of the driver IC 10, and supplies the required control signals and image signals to the scan driver 20, the transmit control driver 30, and the data driver 13.

[0060] In this embodiment, the timing controller 11 includes a first lookup table (LUT1) in which a plurality of first initialization voltages corresponding to a plurality of maximum brightness are recorded. The timing controller 11 can determine the value of the first initialization voltage based on received information related to the target maximum brightness and the first lookup table (LUT1). In some embodiments, the first lookup table (LUT1) may exist outside the timing controller 11.

[0061] The initialization voltage generator 12 can generate at least one initialization voltage. For example, a first initialization voltage can be supplied to the anode of an organic light-emitting diode (OLED) included in the pixel to initialize the amount of charge accumulated in the OLED. Furthermore, for example, a third initialization voltage can be supplied to the gate terminal of a driving transistor included in the pixel to initialize the amount of charge accumulated in the gate electrode of the driving transistor. In this embodiment, the third initialization voltage is not specifically defined, but can have a fixed value. For example, when the first offset value is 0, the third initialization voltage can have a value equal to the value of the first initialization voltage.

[0062] In this embodiment, the initialization voltage generator 12 can generate a first initialization voltage with a predetermined value and supply the generated first initialization voltage to the anode of the first organic light-emitting diode of the first pixel. (See below for further details.) Figure 2 Further details are provided regarding the first pixel, the first organic light-emitting diode, and the first initialization voltage.

[0063] The data driver 13 generates data voltages to be supplied to multiple data lines D1, D2, ..., Dm by receiving control signals and image signals from the timing controller 11. The data voltages generated in the pixel row units can be simultaneously supplied to multiple data lines D1, D2, ..., Dm according to the output control signals included in the control signals.

[0064] The scan driver 20 generates scan signals to be supplied to multiple scan lines S0, S1, S2, ..., Sn by receiving control signals from the timing controller 11. In an embodiment, the scan driver 20 can sequentially supply scan signals to the multiple scan lines S0, S1, S2, ..., Sn. For example, the control signal CONT1 may include a gate start pulse GSP and multiple gate clock signals, and the scan driver 20 may be configured as a shift register to generate scan signals by sequentially passing the gate start pulse to the next stage circuit under the control of the gate clock signals.

[0065] The emission control driver 30 can supply emission control signals for determining the emission period of a plurality of pixels PX11, PX12, ..., PX1m, PX21, PX22, ..., PX2m, ..., PXn1, PXn2, ..., and PXnm to emission control lines E1, E2, ..., and En. For example, each pixel may include an emission control transistor, and the flow of current through the organic light-emitting diode (OLED) can be determined based on the on / off state of the emission control transistor to control the emission of the OLED. In some embodiments, the emission control driver 30 can be configured as a sequential emission type emission control driver that allows light to be emitted sequentially from each pixel row. In another embodiment, the emission control driver 30 can be configured as a simultaneous emission type emission control driver that allows light to be emitted simultaneously from all pixel rows.

[0066] The DC-DC converter 50 can generate multiple power voltages using a power supply. For example, the DC-DC converter 50 can generate a first power voltage and a second power voltage to be used in each pixel. In this embodiment, the first power voltage is less than the second power voltage. Figure 1 In the first embodiment, the initialization voltage generator 12 is illustrated as being spaced apart from the DC-DC converter 50. However, in another embodiment, the initialization voltage generator 12 may be integrated into the DC-DC converter 50. In yet another embodiment, at least a portion of the DC-DC converter 50 may be integrated into the driver IC 10.

[0067] Pixel unit 40 may include multiple pixels PX11, PX12, ..., PX1m, PX21, PX22, ..., PX2m, ..., PXn1, PXn2, ..., and PXnm. Each pixel can be coupled to a corresponding data line and a corresponding scan line, and receives a data voltage input corresponding to the scan signal. Each pixel allows an organic light-emitting diode to emit light corresponding to the input data voltage, and thus, pixel unit 40 displays an image screen.

[0068] Figure 2 This is a diagram illustrating the first pixel according to some exemplary embodiments of the present invention.

[0069] Reference Figure 2 The first pixel PXij includes multiple transistors M1, M2, M3, M4, M5, M6 and M7, a storage capacitor Cst1 and a first organic light-emitting diode OLED1.

[0070] The following description, by way of example, depicts a circuit configured with a P-type transistor. However, those skilled in the art can design a circuit configured with an N-type transistor by changing the polarity of the voltage applied to the gate terminal of the transistor. Similarly, those skilled in the art can design a circuit configured with a combination of P-type and N-type transistors. A P-type transistor is generally referred to as a transistor in which the amount of current flowing through the transistor increases when the voltage difference between the gate terminal and the source terminal increases in the negative direction. An N-type transistor is generally referred to as a transistor in which the amount of current flowing through the transistor increases when the voltage difference between the gate terminal and the source terminal increases in the positive direction. Transistors can be configured in various forms, such as thin-film transistors (TFTs), field-effect transistors (FETs), and bipolar junction transistors (BJTs).

[0071] One electrode of transistor M1 can be coupled to the other electrode of transistor M5, the other electrode of transistor M1 can be coupled to one electrode of transistor M6, and the gate electrode of transistor M1 can be coupled to the other electrode of storage capacitor Cst1. Transistor M1 can be referred to as the first driving transistor. Transistor M1 determines the amount of driving current flowing between the second power voltage ELVDD and the first power voltage ELVSS based on the potential difference between its gate electrode and source electrode.

[0072] One electrode of transistor M2 can be coupled to data line Dj, the other electrode of transistor M2 can be coupled to the same electrode of transistor M1, and the gate electrode of transistor M2 can be coupled to the scan line Si of the current stage. Transistor M2 can be referred to as the first scan transistor. If a scan signal with an on-level is applied to the scan line Si of the current stage, transistor M2 allows the data voltage of data line Dj to be applied to the first pixel PXij.

[0073] One electrode of transistor M3 can be coupled to the other electrode of transistor M1, the other electrode of transistor M3 can be coupled to the gate electrode of transistor M1, and the gate electrode of transistor M3 can be coupled to the scan line Si of the current stage. If a scan signal with a conduction level is applied to the scan line Si of the current stage, transistor M3 can allow transistor M1 to be diode coupled.

[0074] One electrode of transistor M4 can be coupled to the gate electrode of transistor M1, the other electrode of transistor M4 can be coupled to the third initialization voltage VINT3, and the gate electrode of transistor M4 can be coupled to the scan line S(i-1) of the previous stage. In another embodiment, the gate electrode of transistor M4 can be coupled to another scan line. If a scan signal with an on-level is applied to the scan line S(i-1) of the previous stage, transistor M4 allows the amount of charge accumulated in the gate electrode of transistor M1 to be initialized by supplying the third initialization voltage VINT3 to the gate electrode of transistor M1.

[0075] One electrode of transistor M5 can be coupled to the second power voltage ELVDD, and the other electrode of transistor M5 can be coupled to the same electrode of transistor M1. The gate electrode of transistor M5 can be coupled to the emitter control line Ei. One electrode of transistor M6 can be coupled to the same electrode of transistor M1, and the other electrode of transistor M6 can be coupled to the anode of the first organic light-emitting diode OLED1. The gate electrode of transistor M6 can be coupled to the emitter control line Ei. Transistors M5 and M6 can be referred to as emitter control transistors. If an on-level emitter control signal is applied to the emitter control line Ei, transistors M5 and M6 allow the first organic light-emitting diode OLED1 to emit light by forming a current path between the second power voltage ELVDD and the first power voltage ELVSS.

[0076] One electrode of transistor M7 can be coupled to the anode of the first organic light-emitting diode OLED1, the other electrode of transistor M7 can be coupled to the first initialization voltage VINT1, and the gate electrode of transistor M7 can be coupled to the scan line Si of the current stage. In another embodiment, the gate electrode of transistor M7 can be coupled to another scan line. If a scan signal with an on-level is applied to the scan line Si of the current stage, transistor M7 allows the amount of charge accumulated in the first organic light-emitting diode OLED1 to be initialized by supplying the first initialization voltage VINT1 to the anode of the first organic light-emitting diode OLED1.

[0077] The anode of the first organic light-emitting diode OLED1 can be coupled to the other electrode of the transistor M6, and the cathode of the first organic light-emitting diode OLED1 can be coupled to the first power voltage ELVSS. Figure 2 In this diagram, capacitor Co1 can be illustrated to describe the amount of charge accumulated in the first organic light-emitting diode OLED1.

[0078] Figure 3 This is a diagram illustrating the first initialization voltage in the first embodiment when the target maximum brightness is equal to the reference maximum brightness.

[0079] As described above, the first initialization voltage VINT1 is generated by the initialization voltage generator 12. In this embodiment, the first initialization voltage VINT1 can be changed according to the target maximum brightness L_tar. For example, the timing controller 11 can search for a first initialization voltage value corresponding to the target maximum brightness L_tar from among multiple first initialization voltage values ​​corresponding to multiple maximum brightness values ​​in the first lookup table LUT1, and pass the searched first initialization voltage value to the initialization voltage generator 12. The initialization voltage generator 12 can generate the first initialization voltage VINT1 according to the passed first initialization voltage value.

[0080] In this embodiment, multiple first initialization voltage values ​​are obtained by adding a first offset value OFFSET1 to the value of a first power voltage ELVSS. Each of the first offset values ​​OFFSET1 can be approximately inversely proportional to the magnitude of the corresponding maximum brightness.

[0081] The multiple maximum brightness values ​​in the first lookup table LUT1 can include a reference maximum brightness L_ref. The first offset value OFFSET1 at the reference maximum brightness L_ref can be 0. That is, when the target maximum brightness L_tar is equal to the reference maximum brightness L_ref, the value of the first power voltage ELVSS can be approximately equal to the value of the first initialization voltage VINT1.

[0082] exist Figure 3 In this paper, we will use the case where the target maximum brightness L_tar corresponds to the reference maximum brightness L_ref as an example to describe the situation. Figure 2 The driving method for the first pixel PXij.

[0083] At time t1, the data voltage DATA(i-1)j of the previous pixel row is applied to the data line Dj, and the on-level (low-level) scan signal is applied to the previous scan line S(i-1).

[0084] Since a high-level (off-state) scan signal is applied to the current stage's scan line Si, transistor M2 is in the off state, and the data voltage DATA(i-1)j of the previous stage's pixel row is prevented from being applied to the first pixel PXij.

[0085] At this time, since transistor M4 is in the on state, the third initialization voltage VINT3 is applied to the gate electrode of transistor M1, thus initializing the amount of charge accumulated in the gate electrode of transistor M1. Because a cutoff-level emission control signal is applied to the emission control line Ei, transistors M5 and M6 are in the off state, and unnecessary emission of the first organic light-emitting diode OLED1 caused by the application of the third initialization voltage VINT3 is prevented.

[0086] At time t2, the supply of the third initialization voltage VINT3 is stopped because transistor M4 is turned off due to the scan signal at the cutoff level (high level) being applied to the scan line S(i-1) of the previous stage.

[0087] At time t3, the data voltage DATAij of the current stage's pixel row is applied, and a scan signal at the on level is applied to the scan line Si of the current stage. Therefore, transistors M2, M1, and M3 are turned on, causing the data line Dj to be electrically coupled to the gate electrode of transistor M1. Consequently, the data voltage DATAij is applied to the other electrode of the storage capacitor Cst1, and the storage capacitor Cst1 accumulates a large amount of charge corresponding to the difference between the second power voltage ELVDD and the data voltage DATAij.

[0088] At this time, since transistor M7 is in the on state, the first initialization voltage VINT1 is applied to the anode of the first organic light-emitting diode OLED1, and the first organic light-emitting diode OLED1 is pre-charged with a large amount of charge corresponding to the difference between the first initialization voltage VINT1 and the first power voltage ELVSS. In this embodiment, Figure 3 The scenario is where the target maximum brightness L_tar is equal to the reference maximum brightness L_ref and the first offset value OFFSET1 is 0. Therefore, since the first power voltage ELVSS is approximately equal to the first initialization voltage VINT1, there is no voltage difference between the two ends of the first organic light-emitting diode OLED1, and the amount of pre-charged charge in the first organic light-emitting diode OLED1 becomes 0.

[0089] At time t4, since a cutoff level scan signal is applied to the scan line Si of the current stage, the accumulation of charge in the storage capacitor Cst1 ends, the accumulated charge is held, and the initialization of the first organic light-emitting diode OLED1 ends.

[0090] At time t5, transistors M5 and M6 are turned on because a conduction-level emitter control signal is applied to the emitter control line Ei. The amount of drive current flowing through transistor M1 is controlled according to the amount of charge accumulated in storage capacitor Cst1, causing the drive current to flow through the first organic light-emitting diode OLED1. The drive current charges the capacitor Co1 of the first organic light-emitting diode OLED1, and the fully charged first organic light-emitting diode OLED1 emits light until a cutoff-level emitter control signal is applied to the emitter control line Ei.

[0091] The reference maximum brightness L_ref can be defined as the brightness at which sufficient drive current flows to a level where color dragging is not observed. The reference maximum brightness L_ref can be set individually for each product. Therefore, in Figure 3 In this study, color dragging was not observed even when the amount of pre-charged charge in the first organic light-emitting diode OLED1 was 0.

[0092] Figure 4 This is a diagram illustrating the first initialization voltage in the first embodiment when the target maximum brightness is greater than the reference maximum brightness.

[0093] exist Figure 4 In the middle, the driving method of the first pixel PXij and Figure 3 The driving methods are the same, and therefore, redundant descriptions will be omitted.

[0094] The first lookup table LUT1 includes a first maximum brightness group that exceeds the reference maximum brightness L_ref from a plurality of maximum brightness groups, and the first offset value OFFSET1 corresponding to the first maximum brightness group is less than 0. Figure 4 The case is where the target maximum brightness L_tar corresponds to any one of the first maximum brightness groups, that is, where the target maximum brightness L_tar is greater than the reference maximum brightness L_ref.

[0095] Therefore, in Figure 4 In this case, the first initialization voltage VINT1 is less than the first power voltage ELVSS.

[0096] Figure 4 This occurs when the display device is configured to emit light with high brightness. In this case, the amount of driving current supplied to the first organic light-emitting diode OLED1 is greater than... Figure 3 The amount of driving current in this case is reduced, and therefore color dragging is not observed. Therefore, in Figure 4 In this case, a reverse voltage is applied to the first organic light-emitting diode OLED1 to be initialized, so that the degradation of the first organic light-emitting diode OLED1 can be delayed.

[0097] Figure 5 This is a diagram illustrating the first initialization voltage in the first embodiment when the target maximum brightness is less than the reference maximum brightness.

[0098] exist Figure 5 In the middle, the driving method of the first pixel PXij and Figure 3 The driving methods are the same, and therefore, redundant descriptions will be omitted.

[0099] The first lookup table LUT1 includes a second maximum brightness group that is less than the reference maximum brightness L_ref among a plurality of maximum brightness groups, and the first offset value OFFSET1 corresponding to the second maximum brightness group is greater than 0. Figure 5 The case is where the target maximum brightness L_tar corresponds to any one of the second maximum brightness groups, that is, where the target maximum brightness L_tar is less than the reference maximum brightness L_ref.

[0100] Therefore, in Figure 5 In this case, the first initialization voltage VINT1 is greater than the first power voltage ELVSS.

[0101] Figure 5 This occurs when the display device is configured to emit light with low brightness. In this case, the amount of driving current supplied to the first organic light-emitting diode OLED1 is less than... Figure 3 The amount of driving current in this situation. Therefore, since capacitor Co1 is charged slowly, color dragging may be observed.

[0102] Therefore, in Figure 5 In this case, capacitor Co1 is pre-charged during the time interval t3 to t4 according to a first offset value OFFSET1 greater than 0, so that although a relatively small amount of charge is supplied to the first organic light-emitting diode OLED1 through the driving current at time t5, capacitor Co1 is fully charged at the target time, and the first organic light-emitting diode OLED1 begins to emit light. Therefore, color dragging is prevented.

[0103] Figure 6 This is a diagram illustrating an example of the first initialization voltage, the first power voltage, and the second power voltage based on the target's maximum brightness.

[0104] Reference Figure 6 Table 1 shows examples based on the first offset value OFFSET1, the first power voltage ELVSS, and the second power voltage ELVDD for the target maximum brightness L_tar. In Table 1, the unit of brightness is nits (nit), and the unit of voltage is volts (V).

[0105] exist Figure 6 In the middle, based on the first offset value OFFSET1 of the target maximum brightness L_tar and the reference... Figures 3 to 5 The description corresponds to the first offset value OFFSET1, and therefore, repeated descriptions will be omitted.

[0106] According to some exemplary embodiments of the present invention, the first power voltage ELVSS can be approximately inversely proportional to the magnitude of the target maximum brightness L_tar. In this case, regardless of the target maximum brightness L_tar, the second power voltage ELVDD can have a fixed value. Figure 6 In this context, the second power voltage ELVDD is, for example, 4.6V.

[0107] More specifically, the first power voltage ELVSS has a specific voltage value when the target maximum brightness L_tar corresponds to the reference maximum brightness L_ref. Furthermore, the first power voltage ELVSS can have a voltage value lower than the specific voltage value when the target maximum brightness L_tar corresponds to a first maximum brightness group (i.e., under high brightness conditions). Additionally, the first power voltage ELVSS can have a voltage value equal to or higher than the specific voltage value when the target maximum brightness L_tar corresponds to a second maximum brightness group (i.e., under low brightness conditions). (Refer to...) Figure 6 The reference maximum brightness L_ref is, for example, 100 nits, and the specific voltage value of the first power voltage ELVSS is, for example, -2.6V.

[0108] According to some exemplary embodiments of the present invention, under high brightness conditions, the potential difference Vd2 between the second power voltage ELVDD and the first power voltage ELVSS (see...) Figure 4 The increase ensures sufficient driving current. Under low brightness conditions, the potential difference Vd3 between the second power voltage ELVDD and the first power voltage ELVSS (see...) Figure 5 The reduction in voltage allows for lower power consumption. At this time, the potential difference Vd1 between the second power voltage ELVDD and the first power voltage ELVSS (see...) Figure 3 When the target maximum brightness L_tar is the reference maximum brightness L_ref, it becomes the reference.

[0109] Furthermore, as mentioned above, the second power voltage ELVDD can have a fixed value regardless of the target maximum brightness L_tar. However, in another embodiment, the second power voltage ELVDD and the first power voltage ELVSS can be changed such that the difference between the second power voltage ELVDD and the first power voltage ELVSS is maintained, as shown below. Figure 6 As shown.

[0110] Figure 7 This is a diagram illustrating a display device according to some exemplary embodiments of the present invention.

[0111] Reference Figure 7A display device according to some exemplary embodiments of the present invention includes a processor 9, a driver IC 10, a scan driver 20, an emission control driver 30, a pixel unit 40', and a DC-DC converter 50. The driver IC 10 may include a timing controller 11', an initialization voltage generator 12', and a data driver 13.

[0112] exist Figure 7 In the embodiment, the timing controller 11' and the initialization voltage generator 12' are... Figure 1 The timing controller 11 and the initialization voltage generator 12 in the embodiment are different. Figure 7 Other components in the illustrated embodiments and Figure 1 The other components in the illustrated embodiments are largely the same, and therefore, repeated descriptions will be omitted.

[0113] Pixel unit 40' includes a second pixel, the second pixel includes a second organic light-emitting diode, the second organic light-emitting diode has an organic material with a band gap different from that of the organic material of the first organic light-emitting diode OLED1.

[0114] The timing controller 11' further includes a second lookup table LUT2 in which a plurality of second initialization voltage values ​​corresponding to a plurality of maximum brightness are recorded. The timing controller 11' determines the value of the second initialization voltage based on received information related to the target maximum brightness L_tar and the second lookup table LUT2.

[0115] As described above, multiple first initialization voltage values ​​are obtained by adding a first offset value OFFSET1 to the value of the first power voltage ELVSS. In this embodiment, multiple second initialization voltage values ​​are obtained by adding a second offset value to the value of the first power voltage ELVSS. Here, the first offset value OFFSET1 and the second offset value can be different from each other, except at the reference maximum brightness L_ref. This will be discussed later. Figures 12 to 14 Describe in detail.

[0116] The initialization voltage generator 12' further generates a second initialization voltage to be supplied to the anode of the second organic light-emitting diode.

[0117] Figure 8 This is a diagram illustrating an embodiment of a pixel unit according to some exemplary embodiments of the present invention.

[0118] Reference Figure 8 A portion of pixel unit 40' is magnified and illustrated. Pixel unit 40' includes a first pixel PXij and a second pixel PXi(j+1). Figure 8In this context, the first pixel PXij specifies pixel B, and the second pixel PXi(j+1) specifies pixel C. However, the second pixel PXi(j+1) can also specify pixel A.

[0119] The first organic light-emitting diode (OLED1) of pixel B may comprise an organic material having relatively high emission efficiency (i.e., exhibiting high brightness emission compared to energy consumption). The second organic light-emitting diode (OLED2) of pixel A or C may comprise an organic material having relatively low emission efficiency (i.e., exhibiting low brightness emission compared to energy consumption). The organic light-emitting diodes of pixels A and C comprise organic materials having different band gaps from each other. However, pixel B is the object of comparison herein, and therefore, for convenience, the differences between the organic light-emitting diodes of pixel A and pixel C are ignored.

[0120] Therefore, the first organic light-emitting diode OLED1 can have a smaller light-emitting surface area than the second organic light-emitting diode OLED2. Figure 8 The illustration shows a case where pixel B has a smaller area than either pixel A or pixel C.

[0121] Green organic light-emitting diodes (OLEDs) typically offer the highest emission brightness relative to energy consumption. Therefore, the first OLED1 can be a green OLED. In this case, the second OLED2 can be a red or blue OLED. That is, pixel B can be a green pixel, pixel A a red pixel, and pixel C a blue pixel. Alternatively, pixel B can be a green pixel, pixel A a blue pixel, and pixel C a red pixel.

[0122] However, the embodiments disclosed herein are not limited thereto, and new organic materials with high emission efficiency can be developed. In this case, the first organic light-emitting diode OLED1 can be, for example, a blue organic light-emitting diode. In this case, the second organic light-emitting diode can be a green or red organic light-emitting diode.

[0123] Similarly, the first organic light-emitting diode (OLED1) can be, for example, a red organic light-emitting diode. In this case, the second organic light-emitting diode (OLED2) can be a green or blue organic light-emitting diode.

[0124] However, the first organic light-emitting diode (OLED) is not necessarily determined based on luminous efficiency. (See reference...) Figure 8 The sum of the number of pixels A and the number of pixels C is approximately equal to the number of pixels B. Therefore, if the emission efficiencies of organic materials are similar, then... Figure 8 The area of ​​the luminescent surface shown can be determined to control the emission area for each color.

[0125] Figure 8 The structure of the pixel unit 40' shown can be called a P-structure (pentile structure).

[0126] Figure 9 This is a diagram illustrating another example of a pixel unit according to some exemplary embodiments of the present invention.

[0127] Figure 9 Pixel unit 40" and Figure 8 The pixel units 40' are identical in terms of electrical coupling and configuration, and therefore, repeated descriptions will be omitted.

[0128] and Figure 8 The pixel unit 40' is different, in Figure 9 In the pixel unit 40", the light-emitting surface of each pixel can be provided as a diamond shape or a rhombus shape. Figure 9 The 40" pixel unit structure can be called a diamond P structure.

[0129] Figure 10 This is a diagram illustrating the color dragging phenomenon that occurs when the embodiments of this disclosure are not applied.

[0130] Reference Figure 10 The illustration shows the difference in emission time between pixels A, B, and C when the embodiments of this disclosure are not applied.

[0131] For example, in order to represent gray, the light emitted from the organic light-emitting diodes of pixels A, B, and C will be combined when the brightness of each of them reaches a certain level.

[0132] However, in Figure 8 and Figure 9 In the structure of pixel units 40' and 40" shown, the capacitance of the first organic light-emitting diode OLED1 per unit area of ​​pixel B can be large, and the amount of driving current flowing through the first organic light-emitting diode OLED1 of pixel B can be small. Therefore, as Figure 10 As shown, the emission time of pixel B can be later than the emission times of pixels A and C.

[0133] For this reason, only pixels A and C can emit light in the initial period. If pixel A is a red pixel and pixel C is a blue pixel, the color observed by the user could be purple. Therefore, when the user scrolls the gray screen, the user may experience a color dragging effect where purple is observed first.

[0134] Figure 11 This is a diagram illustrating the first and second pixels according to some exemplary embodiments of the present invention.

[0135] Reference Figure 11 The first pixel PXij includes multiple transistors M1, M2, M3, M4, M5, M6 and M7, a storage capacitor Cst1 and a first organic light-emitting diode OLED1. Figure 11 The first pixel PXij and Figure 2 The first pixel PXij is the same, and therefore, duplicate descriptions will be omitted.

[0136] The second pixel PXi(j+1) includes multiple transistors M1', M2', M3', M4', M5', M6', and M7', a storage capacitor Cst1', and a second organic light-emitting diode OLED2. In the second pixel PXi(j+1), the overlapping description of components corresponding to those in the first pixel PXij will be omitted.

[0137] The difference between the second pixel PXi(j+1) and the first pixel PXij is that one electrode of transistor M2' is coupled to the data line D(j+1) and the second initialization voltage VINT2 is applied to the other electrode of transistor M7'.

[0138] As described above, since the first organic light-emitting diode OLED1 of the first pixel PXij has a higher emission efficiency than the second organic light-emitting diode OLED2, a relatively small amount of driving current flows compared to the second pixel PXi(j+1).

[0139] Therefore, under low-brightness conditions where a very small amount of driving current flows, the time required to charge the capacitor Co1 of the first organic light-emitting diode OLED1 is later than the time required to charge the capacitor Co2 of the second organic light-emitting diode OLED2, and therefore, as Figure 10 The color dragging phenomenon shown may occur.

[0140] In Figures 12 to 14 The document describes a driving method for preventing color dragging.

[0141] Figure 12 The diagram illustrates the first and second initialization voltages when the target maximum brightness equals the reference maximum brightness.

[0142] exist Figure 12 In the above, the driving method of the first pixel PXij and the second pixel PXi(j+1) is similar to... Figure 3 The driving methods are largely the same, and therefore, repeated descriptions will be omitted.

[0143] In the reference maximum brightness L_ref, the first offset value OFFSET1 and the second offset value OFFSET2 can be 0. That is, when the target maximum brightness L_tar is equal to the reference maximum brightness L_ref, the first initialization voltage VINT1, the second initialization voltage VINT2, and the first power voltage ELVSS can be approximately equal to each other.

[0144] At this time, during the period from t3 to t4, the potential difference between the two ends of each of the first organic light-emitting diode OLED1 and the second organic light-emitting diode OLED2 is 0V, and therefore the amount of pre-charged charge in each of the first organic light-emitting diode OLED1 and the second organic light-emitting diode OLED2 becomes 0.

[0145] As mentioned above, the reference maximum luminance L_ref can be defined as the luminance at which sufficient driving current flows to a degree in which color dragging is not observed. Therefore, in Figure 12 Even when the amount of pre-charged charge in the first organic light-emitting diode OLED1 and the second organic light-emitting diode OLED2 is 0, color dragging is not observed.

[0146] The first power voltage ELVSS can have a specific voltage value when corresponding to the target maximum brightness L_tar and the reference maximum brightness L_ref. Furthermore, regardless of the target maximum brightness L_tar, the second power voltage ELVDD can have a fixed value. In this case, the potential difference Vd4 between the second power voltage ELVDD and the first power voltage ELVSS becomes what will be described later. Figure 13 and Figure 14 Reference.

[0147] Figure 13 The diagram illustrates the first initialization voltage and the second initialization voltage when the target maximum brightness is greater than the reference maximum brightness in the second embodiment.

[0148] As described above, the first lookup table LUT1 includes a first maximum brightness group that exceeds the reference maximum brightness L_ref among a plurality of maximum brightness groups, and the first offset value OFFSET1 corresponding to the first maximum brightness group is less than 0. Figure 13 The case in which the target maximum brightness L_tar corresponds to any one of the first maximum brightness groups is the case in which the target maximum brightness L_tar is greater than the reference maximum brightness L_ref.

[0149] In this embodiment, the second lookup table LUT2 includes a second offset value OFFSET2 corresponding to the first maximum brightness group. The second offset value OFFSET2 corresponding to the first maximum brightness group is less than the corresponding first offset value OFFSET1.

[0150] Therefore, in Figure 13 In the case where the first initialization voltage VINT1 is less than the first power voltage ELVSS, and the second initialization voltage VINT2 is less than both the first initialization voltage VINT1 and the first power voltage ELVSS.

[0151] Figure 13 The situation is where the display device is configured to emit light with high brightness. In this case, the amount of driving current supplied to the first organic light-emitting diode OLED1 and the second organic light-emitting diode OLED2 is greater than... Figure 12 The amount of driving current in this case is reduced, and therefore color dragging is not observed. Therefore, in Figure 13 In this case, a reverse voltage is applied to the first organic light-emitting diode OLED1 and the second organic light-emitting diode OLED2 to be initialized, so that the degradation of the first organic light-emitting diode OLED1 and the second organic light-emitting diode OLED2 can be delayed.

[0152] Furthermore, the first initialization voltage VINT1 is set to be greater than the second initialization voltage VINT2, so that the capacitor Co1 of the first organic light-emitting diode OLED1 can be pre-charged to a voltage higher than the voltage of the capacitor Co2 of the second organic light-emitting diode OLED2. Therefore, at time t5, the emission start time of the first organic light-emitting diode OLED1 can be further advanced than the emission start time of the second organic light-emitting diode OLED2. Therefore, referring to... Figure 10 This can reduce the interval between the emission start time of pixels A and C and the emission start time of pixel B.

[0153] The first electrical voltage ELVSS can have a voltage value lower than a specific voltage value when the target maximum brightness L_tar corresponds to the first maximum brightness group. That is, the potential difference Vd5 can be greater than Figure 12 Vd4, and therefore the drive current necessary for high-brightness driving can be guaranteed.

[0154] Figure 14 This is a diagram illustrating the first initialization voltage and the second initialization voltage when the target maximum brightness is less than the reference maximum brightness in the second embodiment.

[0155] As described above, the first lookup table LUT1 includes a second maximum brightness group that is less than the reference maximum brightness L_ref among a plurality of maximum brightness groups, and the first offset value OFFSET1 corresponding to the second maximum brightness group is greater than 0. Figure 14 The case in which the target maximum brightness L_tar corresponds to any one of the second maximum brightness groups is the case in which the target maximum brightness L_tar is less than the reference maximum brightness L_ref.

[0156] In this embodiment, the second lookup table LUT2 includes a second offset value OFFSET2 corresponding to the second maximum brightness group. The second offset value OFFSET2 corresponding to the second maximum brightness group is less than the corresponding first offset value OFFSET1.

[0157] Therefore, in Figure 14 In this scenario, the first initialization voltage VINT1 is greater than the first power voltage ELVSS, and the second initialization voltage VINT2 is less than the first initialization voltage VINT1. Alternatively, the second initialization voltage VINT2 may be greater than the first power voltage ELVSS.

[0158] Figure 14 This occurs when the display device is configured to emit light with low brightness. In this case, the amount of driving current supplied to the first organic light-emitting diode OLED1 is less than... Figure 12 The amount of driving current in this situation. Therefore, since capacitor Co1 is slowly charged, color dragging can be observed.

[0159] Therefore, in Figure 14 In this case, capacitor Co1 is pre-charged during the time interval t3 to t4 according to a first offset value OFFSET1 greater than 0, so that although a relatively small amount of charge is supplied to the first organic light-emitting diode OLED1 through the driving current at time t5, capacitor Co1 is fully charged at the target time, and the first organic light-emitting diode OLED1 begins to emit light. Therefore, color dragging is prevented.

[0160] Furthermore, the first initialization voltage VINT1 is set to be greater than the second initialization voltage VINT2, so that the capacitor Co1 of the first organic light-emitting diode OLED1 can be pre-charged to a voltage higher than the voltage of the capacitor Co2 of the second organic light-emitting diode OLED2. Therefore, at time t5, the emission start time of the first organic light-emitting diode OLED1 can be further advanced than the emission start time of the second organic light-emitting diode OLED2. Therefore, referring to... Figure 10 This can reduce the interval between the emission start time of pixels A and C and the emission start time of pixel B.

[0161] The first electrical voltage ELVSS can have a voltage value equal to or higher than a specific voltage value when the target maximum brightness L_tar corresponds to the second maximum brightness group. That is, the potential difference Vd6 is equal to or less than a specific voltage value. Figure 12 The Vd4 value enables a reduction in power consumption.

[0162] The first lookup table LUT1 and the second lookup table LUT2 mentioned above can be configured using a storage device (e.g., a memory).

[0163] According to some example embodiments of this disclosure, in a display device and its driving method, the initialization voltage is controlled according to brightness conditions, so that color dragging can be eliminated or mitigated.

[0164] Electronic or electrical devices and / or any other related devices or components according to embodiments of the invention described herein can be implemented using any suitable hardware, firmware (e.g., application-specific integrated circuits), software, or a combination of software, firmware, and hardware. For example, various components of these devices can be formed on an integrated circuit (IC) chip or a separate IC chip. Furthermore, various components of these devices can be implemented on flexible printed circuit films, tape-on-a-package (TCP), printed circuit boards (PCBs), or formed on a substrate. Additionally, various components of these devices can be processes or threads that run on one or more processors in one or more computing devices, execute computer program instructions, and interact with other system components to perform the various functions described herein. The computer program instructions are stored in memory, which can be implemented in the computing device using standard memory devices (e.g., random access memory (RAM)). The computer program instructions can also be stored in other non-transitory computer-readable media (e.g., CD-ROMs, flash drives, etc.). Furthermore, those skilled in the art will recognize that, without departing from the spirit and scope of exemplary embodiments of the invention, the functions of various computing devices can be combined or integrated in a single computing device, or the functions of a particular computing device can be distributed across one or more other computing devices.

[0165] This document has disclosed aspects of exemplary embodiments, and although specific terminology has been used, it is used and interpreted in a general and descriptive sense only and not for limiting purposes. In some instances, as will be apparent to those skilled in the art at the time of filing this application, features, characteristics, and / or elements described in connection with particular embodiments may be used alone or in combination with features, characteristics, and / or elements described in connection with other embodiments, unless expressly stated otherwise. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of this disclosure as set forth in the appended claims and their equivalents.

Claims

1. A display device, comprising: The first pixel includes a first light-emitting diode; as well as An initialization voltage generator is configured to generate a first initialization voltage to be supplied to the anode of the first light-emitting diode. The first initialization voltage is determined by adding a first offset value to the value of the first power voltage to be supplied to the cathode of the first light-emitting diode. The first offset value is determined based on the target's maximum brightness.

2. The display device according to claim 1, wherein, The first first offset value corresponding to the first maximum brightness in the first offset value is different from the second first offset value corresponding to the second maximum brightness which is different from the first maximum brightness in the first offset value.

3. The display device according to claim 2, wherein, When the first maximum brightness is greater than the second maximum brightness, the first first offset value in the first offset value is less than the second first offset value in the first offset value.

4. The display device according to claim 2, in, The third first offset value in the first offset value that corresponds to the reference maximum brightness is 0.

5. The display device according to claim 4, in, The reference maximum brightness is less than the first maximum brightness and greater than the second maximum brightness, and Wherein, the first offset value in the first offset value is less than 0.

6. The display device according to claim 5, wherein, The second first offset value in the first offset value is greater than 0.

7. The display device according to claim 6, wherein, The first power voltage is determined based on the magnitude of the target's maximum brightness.

8. The display device according to claim 6, in, First power voltage: It has a specific voltage value when the target maximum brightness corresponds to the reference maximum brightness; and The voltage value is lower than the specific voltage value when the target maximum brightness corresponds to the first maximum brightness.

9. The display device according to claim 8, wherein, The first power voltage has a voltage value equal to or greater than the specific voltage value when the target maximum brightness corresponds to the second maximum brightness.

10. The display device according to claim 9, wherein, Regardless of the target's maximum brightness, the second electrical voltage supplied to the anode of the first light-emitting diode has a fixed value.

11. A display device, comprising: The first pixel includes a first light-emitting diode; as well as An initialization voltage generator is configured to generate a first initialization voltage to be supplied to the anode of the first light-emitting diode. The first initialization voltage corresponding to the first maximum brightness is different from the first initialization voltage corresponding to the second maximum brightness, which is different from the first maximum brightness. The first initialization voltage is determined by adding a first offset value to the value of the first power voltage to be supplied to the cathode of the first light-emitting diode. The first offset value is determined based on the target's maximum brightness.

12. The display device according to claim 11, wherein, The first first offset value corresponding to the first maximum brightness in the first offset value is different from the second first offset value corresponding to the second maximum brightness in the first offset value.

13. The display device according to claim 12, wherein, When the first maximum brightness is greater than the second maximum brightness, the first first offset value in the first offset value is less than the second first offset value in the first offset value.

14. The display device according to claim 12, in, The third first offset value in the first offset value that corresponds to the reference maximum brightness is 0.

15. The display device according to claim 14, in, The reference maximum brightness is less than the first maximum brightness and greater than the second maximum brightness, and Wherein, the first offset value in the first offset value is less than 0.

16. The display device according to claim 15, wherein, The second first offset value in the first offset value is greater than 0.

17. The display device according to claim 16, wherein, The first power voltage is determined based on the magnitude of the target's maximum brightness.

18. The display device according to claim 16, in, First power voltage: It has a specific voltage value when the target maximum brightness corresponds to the reference maximum brightness; and The voltage value is lower than the specific voltage value when the target maximum brightness corresponds to the first maximum brightness.

19. The display device according to claim 18, wherein, The first power voltage has a voltage value equal to or greater than the specific voltage value when the target maximum brightness corresponds to the second maximum brightness.

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