KR20200123331A - Display device and method for controlling brightness of the same - Google Patents

Abstract

According to an embodiment of the present invention, a display device includes: a display area including pixels connected to scan lines, emission control lines, and data lines; and a display driver for driving the pixels in response to input image data, timing signals, and luminance selection signals; and a control unit which divides a first luminance region and a second luminance region based on a predetermined reference luminance level and controls the luminance of the display area in a first luminance control mode and a second luminance control mode, respectively, in the first luminance region and the second luminance region. A first gamma data set includes gamma data corresponding to a sample luminance level set such that the emission time of the pixels is reduced within a range of 10% or less compared to the reference luminance level, thereby preventing luminance reversal from occurring between luminance levels.

Description

A display device and its luminance control method TECHNICAL FIELD

Embodiments of the present invention relate to a display device and a method for adjusting brightness thereof.

In general, the display device determines display luminance for each gray level through gamma setting. For example, the display device may generate a data signal corresponding to each gray level by using gamma data set in advance for predetermined reference gray levels, and display an image with a luminance corresponding to the data signal.

In addition, the display device may select one of a plurality of preset luminance levels (eg, dimming levels) and adjust the luminance of the display area according to the selected luminance level. For example, the display device can adjust the luminance of the display area by determining a luminance level in response to an initial setting or a luminance selection signal according to a user input, and generating a data signal using gamma data corresponding to each luminance level. have.

An object of the present invention is to provide a display device and a method for adjusting brightness thereof.

A display device according to an embodiment of the present invention drives the pixels in response to a display area including pixels connected to scan lines, emission control lines, and data lines, and input image data, timing signals, and luminance selection signals. And a display driving unit. The display driver divides a first luminance region and a second luminance region based on a predetermined reference luminance level, and a first luminance control mode and a second luminance control mode in the first luminance region and the second luminance region, respectively. A luminance control unit that controls the luminance of the display area, gamma data corresponding to the reference luminance level, a first gamma data set corresponding to sample luminance levels of the first luminance area, and a sample luminance of the second luminance area And a storage unit in which a second gamma data set corresponding to the levels is stored. The first gamma data set includes gamma data corresponding to a sample luminance level set such that the emission time of the pixels is reduced within a range of 10% or less compared to the reference luminance level.

In an embodiment, the luminance control unit, in the first luminance control mode, adjusts the light emission time of the pixels and gamma data of reference grayscales according to each luminance level belonging to the first luminance region to adjust the luminance of the display region. And, in the second luminance control mode, the luminance of the display region may be controlled by adjusting gamma data of the reference grayscales according to respective luminance levels belonging to the second luminance region.

In an embodiment, the luminance control unit includes: a mode selection unit for selecting one of the first and second luminance control modes in response to the luminance selection signal; A duty control unit controlling the emission time of the pixels to be reduced by corresponding to each luminance level in the first luminance control mode, and controlling the emission time of the pixels to be maintained at a predetermined time in the second luminance control mode; And a gamma control unit configured to output reference gamma data according to each luminance level corresponding to the luminance selection signal with reference to the storage unit in the first and second luminance control modes.

In one embodiment, the mode selector includes section information on the first and second luminance regions, and selects any one of the first and second luminance control modes using the section information. I can.

In an embodiment, the duty controller may output a light emission start signal having a pulse width corresponding to the light emission time of the pixels.

In an embodiment, the display device may further include a light emission control driver configured to sequentially supply light emission control signals to the light emission control lines in response to the light emission start signal.

In an embodiment, in the first luminance control mode, the duty controller may adjust and output a pulse width of the emission start signal so that an off duty of the emission control signal increases as the luminance level decreases.

In an embodiment, in the second luminance control mode, the duty control unit may output the light emission start signal so that the off duty of the light emission control signal remains constant regardless of the luminance level.

In an embodiment, the display device may further include a scan driver that sequentially supplies scan signals to the scan lines so as to be synchronized with a gate-off period of the emission control signal.

In an embodiment, in the first and second luminance control modes, the gamma controller may differentially adjust and output gamma data of reference grayscales according to the luminance level.

In an embodiment, the display device may further include a data driver generating data signals corresponding to the input image data by using gamma data of the reference grayscales and supplying the data signals to the data lines. .

In an embodiment, the storage unit comprises, for each of the reference luminance level, sample luminance levels of the first luminance region, and sample luminance levels of the second luminance region, reference gamma voltages corresponding to the reference gradations are It may include a multi-view programming (MTP) register that is stored repeatedly.

In an embodiment, the sample luminance levels of the first luminance region may include a sample luminance level in which the emission time of the pixels is set in a range of 90% to 95% compared to the reference luminance level.

According to an embodiment of the present invention, a method for adjusting luminance of a display device includes a predetermined reference luminance level, at least one standard luminance level lower than the reference luminance level, and at least one standard luminance level higher than the reference luminance level. Setting standard luminance levels; Setting and storing gamma data for reference gray scales for each of the standard luminance levels; Executing a first brightness control mode or a second brightness control mode in response to the brightness selection signal; And adjusting the luminance of the display area by adjusting the gamma data and the emission time of the pixels according to each luminance level in the first luminance control mode, and the gamma data according to each luminance level in the second luminance control mode. And adjusting the brightness of the display area. The standard luminance levels include a sample luminance level set such that the emission time of the pixels decreases by a range within 10% compared to the reference luminance level.

In one embodiment, in the first luminance control mode, as the luminance level decreases, the emission time of the pixels is reduced. In the second luminance control mode, the emission time of the pixels is constant regardless of the luminance level. Can be maintained.

In an embodiment, in the step of setting the standard luminance levels, a luminance level in which the emission time of the pixels is set in a range of 90% to 95% compared to the reference luminance level may be set as one of the standard luminance levels.

According to the display device and the luminance adjusting method thereof according to an exemplary embodiment of the present invention, a luminance reversal phenomenon may be prevented from occurring between luminance levels, and luminance of a display area may be naturally adjusted according to each luminance level.

1 is a block diagram showing a display device according to an exemplary embodiment of the present invention.
2 is a circuit diagram showing a pixel according to an embodiment of the present invention.
3 is a waveform diagram illustrating an exemplary embodiment of driving signals input to the pixel of FIG. 2.
4 is a graph showing a change in luminance according to a luminance level according to an embodiment of the present invention.
5 is a graph illustrating a method of adjusting luminance of a display device according to an exemplary embodiment of the present invention.
6 is a graph showing a difference in luminance between luminance levels in a second luminance region.
7 is a waveform diagram of a light emission control signal for explaining a duty adjustment method applied to a first luminance region.
8 is a graph showing a deviation between an actual luminance measured in the first luminance region and a target luminance according to sample luminance levels of a first luminance region set according to an embodiment of the present invention.
9 is a waveform diagram of a light emission control signal for explaining the luminance inversion phenomenon of FIG. 8.
10 is a graph showing on/off characteristics of a transistor for explaining the luminance inversion phenomenon of FIG. 8.
11 and 12 are graphs showing actual luminance measured in the first luminance region according to sample luminance levels in the first luminance region set according to another embodiment of the present invention.
13 is a block diagram showing a brightness control unit and a storage unit according to an embodiment of the present invention.
14 is a flowchart illustrating a method of adjusting luminance of a display device according to an exemplary embodiment of the present invention.

In the present invention, various modifications can be made and various forms can be applied, and specific embodiments will be illustrated in the drawings and described in detail in the text. However, the present invention is not limited to the embodiments disclosed below, and may be changed in various forms and implemented. In addition, in the description below, expressions in the singular also include expressions in the plural unless the context clearly includes only the singular.

In the drawings, some constituent elements that are not directly related to the features of the present invention may be omitted in order to clearly indicate the present invention. In addition, some of the components in the drawings may have their size or ratio somewhat exaggerated. Throughout the drawings, the same or similar components are assigned the same reference numerals and reference numerals as much as possible even though they are displayed on different drawings, and redundant descriptions will be omitted.

1 is a block diagram showing a display device 10 according to an exemplary embodiment of the present invention. According to an exemplary embodiment, the organic light emitting display device is illustrated in FIG. 1 by way of example, but the type of the display device 10 according to the present invention is not limited thereto.

Referring to FIG. 1, a display device 10 according to an exemplary embodiment of the present invention includes a display area 100 including a plurality of pixels PX, and a display driver for driving the pixels PX. Includes 200.

The display area 100 includes scan lines S0 to Sn and emission control lines E1 to En, and data lines D1 to crossing the scan lines S0 to Sn and emission control lines E1 to En. Dm), and pixels PX connected to the scan lines S0 to Sn, emission control lines E1 to En, and data lines D1 to Dm. In describing the embodiments of the present invention, the term "connection" may mean a physical and/or electrical connection. For example, the pixels PX may be electrically connected to the scan lines S0 to Sn, the emission control lines E1 to En, and the data lines D1 to Dm.

The scan lines S0 to Sn are connected between the scan driver 210 of the display driver 200 and the pixels PX. The scan lines S0 to Sn transfer scan signals output from the scan driver 210 to the pixels PX. The scan signals control timing at which a data signal is input to each pixel PX.

The emission control lines E1 to En are connected between the emission control driver 220 of the display driver 200 and the pixels PX. The emission control lines E1 to En transfer emission control signals output from the emission control driver 220 to the pixels PX. The emission control signals control the emission time of each pixel PX.

The data lines D1 to Dm are connected between the data driver 230 of the display driver 200 and the pixels PX. The data lines D1 to Dm transfer data signals output from the data driver 230 to the pixels PX. The data signals control the emission luminance of each pixel PX.

The pixels PX receive respective scan signals, emission control signals, and data signals from the scan lines S0 to Sn, the emission control lines E1 to En, and the data lines D1 to Dm. Further, the pixels PX receive driving power from a power supply unit (not shown). For example, the pixels PX may receive a first power ELVDD as a high potential driving power and a second power ELVSS as a low potential driving power. The pixels PX emit light having a luminance corresponding to a data signal in each light emission period. Meanwhile, when a data signal corresponding to a black gray scale (0 gray scale) is supplied to each pixel PX, the corresponding pixel PX may maintain a non-emission state even during the light emission period of the frame.

In an exemplary embodiment, the pixels PX may be self-emission-type pixels including respective light-emitting devices, but are not limited thereto. For example, the type, structure, and/or driving method of the pixels PX may be variously changed according to exemplary embodiments.

The display driver 200 drives the pixels PX in response to input image data DATA, timing signals, and a luminance selection signal SEL. The display driver 200 performs operations of the scan driver 210, the emission control driver 220 and the data driver 230, and the scan driver 210, the emission control driver 220, and the data driver 230. It may include a control unit 240 for controlling. Depending on the embodiment, the scan driver 210, the emission control driver 220, the data driver 230, and/or the controller 240 may be integrated into one driver IC, but the present invention is not limited thereto.

The scan driver 210 receives the first control signal CONT1 from the control unit 240 and supplies the scan signal to the scan lines S0 to Sn in response to the first control signal CONT1. For example, the scan driver 210 receives a first control signal CONT1 including a scan start signal (eg, a sampling pulse input to the first scan stage) and a scan clock signal, and scan lines ( S0 to Sn) can be sequentially outputted. According to an embodiment, the scan driver 210 sequentially outputs scan signals to the scan lines S0 to Sn so as to be synchronized with the gate-off period of each light emission control signal supplied to the light emission control lines E1 to En. can do. For example, during a period in which the emission control signal of the gate-off voltage is supplied to the pixels PX of the first horizontal line through the first emission control line E1, the scan driver 210 A scan signal of a gate-on voltage for selecting the pixels PX of the first horizontal line may be output through (S1). When the pixels PX are selected in units of horizontal lines by each scan signal, the selected pixels PX receive a data signal of a corresponding frame from the data lines D1 to Dm. Depending on the embodiment, the scan driver 210 may be formed or mounted on a display panel together with the pixels PX, or may be formed inside a driving IC.

The emission control driver 220 receives the second control signal CONT2 from the controller 240 and supplies the emission control signal to the emission control lines E1 to En in response to the second control signal CONT2. For example, the light emission control driver 220 receives a second control signal CONT2 including a light emission start signal (eg, a sampling pulse input to the first light emission stage) and a light emission clock signal, and controls light emission in response thereto. Light emission control signals may be sequentially output to the lines E1 to En. Depending on the embodiment, the light emission control driver 220 may be formed or mounted on the display panel together with the pixels PX, or may be formed inside the driving IC. In addition, the emission control driver 220 may be integrated into one gate driver together with the scan driver 210, or may be formed or mounted separately from the scan driver 210.

In one embodiment, the emission control signal may have a gate-off voltage of a predetermined level and duty. The pixels PX receiving the emission control signal are controlled to non-emit light during a period in which the emission control signal has a gate-off voltage, and correspond to a data signal during a period in which the emission control signal has a gate-on voltage. Thus, it can be set in a state in which light can be emitted.

The data driver 230 receives the third control signal CONT3 and the image data DATA from the controller 240 and generates a data signal corresponding to the third control signal CONT3 and the image data DATA. . The generated data signal is output to the data lines D1 to Dm. For example, the data driver 230 receives the third control signal CONT3 and image data DATA including a source sampling pulse, a source sampling clock, and a source output enable signal, and the corresponding horizontal Data signals corresponding to the pixels PX selected during the period may be output to the data lines D1 to Dm. Depending on the embodiment, the data driver 230 may be formed or mounted on the display panel together with the pixels PX, or may be formed inside the driver IC.

The control unit 240 receives timing signals and image data DATA from an external (for example, a host processor), and corresponds to the timing signals and image data DATA, the scan driver 210 and the emission control driver ( 220) and the data driver 230 are driven. For example, the control unit 240 receives timing signals including a vertical synchronization signal (VSYNC), a horizontal synchronization signal (HSYNC), and a main clock signal (MCLK), and controls first, second, and third controls in response thereto. Signals CONT1, CONT2, and CONT3 may be output. The first, second and third control signals CONT1, CONT2, and CONT3 are supplied to the scan driver 210, the emission control driver 220, and the data driver 230, respectively. In addition, the controller 240 may rearrange the image data DATA according to a specification and/or a driving mode of the display panel, and output the rearranged image data DATA to the data driver 230. The image data DATA input to the data driver 230 is used to generate a data signal. Depending on the embodiment, the controller 240 may be configured as a timing controller, or may be configured as a signal controller including a timing controller.

In an exemplary embodiment of the present invention, the display device 10 includes information on a plurality of preset luminance levels, and may be driven with a luminance corresponding to a selected luminance level among the luminance levels. According to an embodiment, the luminance levels are for stepwise adjustment of the luminance of the display area 100, that is, the luminance of the pixels PX according to each luminance level. For example, a plurality of preset dimming levels It can be composed of.

In this case, the control unit 240 receives the luminance selection signal SEL from the outside, and the scan driving unit 210 emits light so that the luminance of the display area 100 is adjusted to a luminance level corresponding to the luminance selection signal SEL. The control driving unit 220 and/or the data driving unit 230 may be controlled. According to an embodiment, the luminance selection signal SEL may be a signal corresponding to a luminance level according to an initial setting or a signal corresponding to a luminance level selected according to a user input.

In an embodiment, the control unit 240 converts reference gamma data (eg, gamma voltages for predetermined reference gray levels) (VGAM) corresponding to the input luminance selection signal SEL to the data driver 230. Can supply. For example, the controller 240 may output gamma voltages of reference grayscales according to a luminance level corresponding to the luminance selection signal SEL to the data driver 230. Then, the data driver 230 generates data signals corresponding to the input image data (or image data converted from the input image data) (DATA) using gamma voltages of the reference gray levels, and converts the data signals into data. It can be supplied by lines (D1 to Dm). Accordingly, the luminance of the pixels PX may be adjusted according to the selected luminance level.

In addition, the control unit 240 may gradually change the gate-off period of the light emission control signal for luminance levels within a predetermined range, for example, luminance levels belonging to a low luminance region below a predetermined reference luminance level. For example, for the luminance levels in the low luminance region, the control unit 240 adjusts the pulse width of the emission start signal in response to the emission time of the pixels PX set according to each luminance level, and adjusts the same. The generated light emission start signal may be included in the second control signal CONT2 and supplied to the light emission control driver 220. Accordingly, the light emission control driver 220 may output a light emission control signal having an on/off duty corresponding to the selected luminance level. When the luminance is adjusted by changing the on/off duty of the emission control signal, the luminance of the display region 100 can be more effectively adjusted even in a low luminance region driving the display region 100 with a relatively low driving current.

To this end, the control unit 240 may include a luminance control unit 250 for controlling the luminance of the display area 100 in response to the luminance selection signal SEL. In addition, the display driving unit 200 may further include a storage unit (not shown) for storing information necessary for the operation of the luminance control unit 250. Depending on the embodiment, the storage unit may be configured inside the control unit 240, but is not limited thereto.

The luminance control unit 250 includes a low luminance region including luminance levels lower than the reference luminance level (hereinafter, referred to as “first luminance region”) based on a predetermined reference luminance level, and a luminance higher than the reference luminance level. A high luminance region including levels (hereinafter, referred to as a “second luminance region”) may be classified, and the luminance of the display region 100 may be controlled in a different manner according to the luminance region to which each luminance level belongs. The reference luminance level may be considered to be included in the first luminance area or the second luminance area, or may be considered to be overlapped in the first luminance area and the second luminance area. For example, the luminance controller 250 controls the luminance of the display region 100 by executing a first luminance control mode in the first luminance region, and in a second luminance region in a different manner from the first luminance control mode. The luminance of the display area 100 may be controlled by executing the driven second luminance control mode.

According to an embodiment, the luminance control unit 250 may execute the first luminance control mode when the luminance level according to the luminance selection signal SEL belongs to the first luminance region. In one embodiment, the luminance control unit 250, during the period in which the first luminance control mode is executed, the emission time of the pixels PX according to each luminance level belonging to the first luminance region (for example, "on Duty") and gamma data VGAM of the reference grayscales may be adjusted to control the luminance of the display area 100.

Meanwhile, when the luminance level according to the luminance selection signal SEL belongs to the second luminance region, the luminance control unit 250 may execute the second luminance control mode. In an embodiment, the luminance control unit 250 adjusts gamma data VGAM of reference grayscales according to each luminance level belonging to the second luminance region during a period in which the second luminance control mode is being executed, so that the display region ( 100) brightness can be controlled. In addition, the luminance control unit 250 maintains the emission time of the pixels PX at a preset value (for example, a predetermined maximum emission time) regardless of the luminance level during the period in which the second luminance control mode is executed. I can.

For convenience, in the following description, based on the emission time of the pixels PX applied to the second luminance control mode, the emission duty according to each luminance level will be set. For example, when the on duty of the pixels PX is 100% (or the off duty is 0%) at a certain luminance level, the emission time of the pixels PX corresponds to the second luminance control mode. It may mean that the maximum light emission time is set. In addition, when the on-duty of the pixels PX at different luminance levels is 90% (or the off-duty is 10%), the emission time of the pixels PX is in the second luminance control mode. It may mean that the light emission time is set to approximately 90% of the corresponding maximum light emission time.

As described above, the display device 10 according to an embodiment of the present invention divides luminance regions around a predetermined reference luminance level, and controls the luminance of the display region 100 in a different manner for each luminance region. do. For example, the display device 10 controls the luminance of the display region 100 through a gamma adjustment method in which gamma data VGAM is adjusted according to the luminance level in a high luminance region including luminance levels equal to or higher than the reference luminance level, In a low luminance region including luminance levels lower than the reference luminance level, a gamma adjustment method and a duty adjustment method for adjusting the emission time of the pixels PX may be applied in combination to control the luminance of the display region 100. have. Accordingly, in terms of the luminance characteristics and power consumption of the display device 10, the luminance of the display area 100 can be efficiently and naturally adjusted according to the luminance level.

2 is a circuit diagram showing a pixel PX according to an embodiment of the present invention. According to an embodiment, the pixel PX illustrated in FIG. 2 may be any one of the pixels PXL disposed in the display area 100 of FIG. 1. For example, the pixel PX shown in FIG. 2 may be a pixel disposed on an n (n is a natural number)-th horizontal line and an m-th vertical line of the display area 100, and pixels in the display area 100 (PX) may have substantially the same or similar structure to each other.

Referring to FIG. 2, a pixel PX according to an embodiment of the present invention includes a light emitting element LD for generating light having a luminance corresponding to a data signal DS, and controlling the light emitting element LD. It may include a pixel circuit (PXC) for.

The first power ELVDD and the second power ELVSS may have different potentials. For example, the first power ELVDD may be set as a high potential power source, and the second power ELVSS may be set as a low potential power source. A potential difference between the first power ELVDD and the second power ELVSS, that is, a voltage applied therebetween, may be greater than the threshold voltage of the light emitting element LD.

The light emitting device LD is connected between the first power ELVDD and the second power ELVSS. For example, one electrode (for example, an anode electrode) of the light emitting device LD is connected to the first power ELVDD via the pixel circuit PXC, and the other electrode of the light emitting device LD (for example, , Cathode electrode) may be connected to the second power ELVSS. The light emitting device LD emits light with a luminance corresponding to a driving current supplied from the pixel circuit PXC.

Depending on the embodiment, the light emitting device LD may be an organic light emitting diode (OLED) including an organic light emitting layer, but is not limited thereto. For example, in another embodiment, ultra-small inorganic light emitting devices as small as nanoscale to microscale may constitute a light source unit of each pixel PX.

The pixel circuit PXC is connected between the first power source ELVDD and the light emitting element LD. Further, the pixel circuit PXC includes at least one scan line including a scan line of a corresponding horizontal line, for example, an n-th scan line (hereinafter referred to as “scan line” or “current scan line”) (Sn), and a data line of the vertical line. , For example, it is connected to the m-th data line (hereinafter referred to as “data line”) Dm. Meanwhile, the location of the pixel circuit PXC is not limited thereto. For example, in another embodiment, the pixel circuit PXC may be connected between the light emitting element LD and the second power ELVSS. The pixel circuit PXC generates a driving current corresponding to the data signal DS supplied from the data line Dm.

In an embodiment, the pixel circuit PXC may include first to sixth transistors M1 to M6 and a storage capacitor Cst. Depending on the embodiment, all of the first to sixth transistors M1 to M6 may be transistors of the same type. For example, all of the first to sixth transistors M1 to M6 may be P-type transistors. However, the present invention is not limited thereto. For example, in another embodiment of the present invention, all of the first to sixth transistors M1 to M6 are N-type transistors, or at least one of the first to sixth transistors M1 to M6 is P Type transistors and the rest may be N type transistors.

The first transistor M1 is a driving transistor of each pixel PX, and is connected between the first power ELVDD and the light emitting element LD. As an example, the first transistor M1 is a light emitting device through a first electrode (for example, a source electrode) and a sixth transistor M6 connected to the first power ELVDD via the fifth transistor M5. A second electrode (eg, a drain electrode) connected to LD, and a gate electrode connected to the first node N1 may be included. The first transistor M1 generates a driving current corresponding to the data signal DS supplied to the first node N1 via the data line Dm.

The second transistor M2 is connected between the data line Dm and the first electrode of the first transistor M1, and the gate electrode of the second transistor M2 is connected to the scan line Sn. The second transistor M2 is turned on when a scan signal (also referred to as a “current scan signal”) SSn of a gate-on voltage is supplied from the scan line Sn. When the second transistor M2 is turned on, the data signal DS supplied to the data line Dm is transmitted to the first electrode of the first transistor M1.

The third transistor M3 is connected between the second electrode of the first transistor M1 and the first node N1, and the gate electrode of the third transistor M3 is connected to the scan line Sn. The third transistor M3 is turned on when the scan signal SSn of the gate-on voltage is supplied from the scan line Sn. When the third transistor M3 is turned on, the first transistor M1 is connected in a diode shape.

The fourth transistor M4 is connected between the first node N1 and the initialization power Vint, and the gate electrode of the fourth transistor M4 is an initialization control line of a corresponding horizontal line, for example, a horizontal line immediately preceding it. May be the current scan line (hereinafter, referred to as “previous scan line”) (that is, the n-1th scan line Sn-1). However, the present invention is not limited thereto. For example, in another embodiment, initialization control lines separate from the scan lines may be provided. The fourth transistor M4 is turned on when the previous scan signal SSn-1 of the gate-on voltage is supplied to the previous scan line Sn-1. When the fourth transistor M4 is turned on, the first node N1 is initialized to the voltage of the initialization power Vint. According to an embodiment, the voltage of the initialization power Vint may be a voltage equal to or less than the lowest voltage of the data signal DS. For example, the voltage of the initialization power Vint may be a voltage lower than the threshold voltage of the first transistor M1 than the lowest voltage of the data signal DS. Accordingly, during each frame period, regardless of the voltage of the data signal DS supplied in the previous frame period, the data signal DS can be stably supplied to the first node N1.

The fifth transistor M5 is connected between the first power ELVDD and the first electrode of the first transistor M1, and the gate electrode of the fifth transistor M5 is a light emission control line of a corresponding horizontal line, one For example, it is connected to the n-th emission control line (hereinafter referred to as "emission control line") En. The fifth transistor M5 is turned off when the light emission control signal ESn of the gate-off voltage is supplied to the light emission control line En, and in other cases (that is, the voltage of the light emission control signal ESn). It is turned on at this gate-on voltage). When the fifth transistor M5 is turned off, the connection between the first power ELVDD and the first transistor M1 is cut off, and when the fifth transistor M5 is turned on, the first transistor M1 Is connected to the first power ELVDD.

The sixth transistor M6 is connected between the second electrode of the first transistor M1 and the light emitting element LD, and the gate electrode of the sixth transistor M6 is connected to the emission control line En. . The sixth transistor M6 is turned off when the light emission control signal ESn of the gate-off voltage is supplied to the light emission control line En, and in other cases (that is, the voltage of the light emission control signal ESn). It is turned on at this gate-on voltage). When the sixth transistor M6 is turned off, the connection between the first transistor M1 and the light emitting element LD is cut off, and when the sixth transistor M6 is turned on, the first transistor M1 is It is connected to the light-emitting element LD.

These fifth and sixth transistors M5 and M6 are light emission control transistors that control light emission of each pixel PX, and are driven according to on/off of the fifth and sixth transistors M5 and M6. It is determined whether or not a current path through which current can flow is formed. Accordingly, by adjusting the pulse duty of the emission control signal ESn for controlling the on/off of the fifth and sixth transistors M5 and M6, the emission time of each pixel PX can be adjusted.

The storage capacitor Cst is connected between the first power ELVDD and the first node N1. The storage capacitor Cst is a voltage corresponding to the data signal DS transmitted to the first node N1 and the threshold voltage of the first transistor M1 during each frame period (especially, the data programming period of each frame) To charge.

Meanwhile, the structure of the pixel circuit PXC is not limited to the embodiment illustrated in FIG. 2. For example, the pixel circuit PXC may have various currently known structures.

3 is a waveform diagram illustrating an exemplary embodiment of driving signals input to the pixel PX of FIG. 2. For example, FIG. 3 illustrates a previous scan signal SSn supplied to a previous scan line Sn-1, a current scan line Sn, a data line Dm, and an emission control line En connected to the pixel PX of FIG. 2. -1), an exemplary waveform of the current scan signal SSn, the data signal DS, and the emission control signal ESn is shown. The previous scan signal SSn-1, the current scan signal SSn, the data signal DS, and the emission control signal ESn may be supplied to the pixels PX in a frame period.

2 and 3, first, a previous scan signal SSn-1 of a gate-on voltage (for example, a low level voltage) is supplied through a previous scan line Sn-1 during an initialization period of the pixel PX. do. Accordingly, the fourth transistor M4 is turned on and the voltage of the first node N1 is initialized to the voltage of the initialization power Vint.

Thereafter, during the data programming period of the pixel PX, the current scan signal SSn of the gate-on voltage (for example, a low level voltage) is supplied through the current scan line Sn. Accordingly, the second and third transistors M2 and M3 are turned on. When the third transistor M3 is turned on, the first transistor M1 is connected in a diode shape. When the second transistor M2 is turned on, the first node N1 is connected to the data line Dm, and the data signal DS supplied to the data line Dm is transferred to the second transistor M2 and the second transistor M2. It is transferred to the first node N1 through the first transistor M1 and the third transistor M3 in order. Accordingly, a voltage corresponding to the data signal DS and the threshold voltage of the first transistor M1 (for example, a voltage difference between the voltage of the data signal DS and the threshold voltage of the first transistor M1) is first It is supplied to the node N1. The voltage supplied to the first node N1 is stored in the storage capacitor Cst.

Meanwhile, during the initialization period and the data programming period in which the previous scan signal SSn-1 and the current scan signal SSn of the gate-on voltage are supplied, respectively, a gate-off voltage (for example, A light emission control signal ESn of a high level voltage) is supplied. Accordingly, while the fifth and sixth transistors M5 and M6 remain off during the initialization period and the data programming period, it is possible to prevent the pixel PX from emitting light with unintended luminance.

Thereafter, during the light emission period EP of the pixel PX, the voltage of the light emission control signal ESn is changed to a gate-on voltage (for example, a low level voltage). Accordingly, while the fifth and sixth transistors M5 and M6 are turned on, the fifth transistor M5, the first transistor M1, the sixth transistor M6, and the light emission from the first power ELVDD. A current path leading to the second power source ELVSS is formed through the device LD in sequence. During the light emission period EP, a driving current corresponding to the voltage of the first node N1 is generated by the first transistor M1, and the driving current flows through a current path formed in the pixel PX. Accordingly, the light emitting element LD emits light with a luminance corresponding to the data signal DS. At this time, since the voltage obtained by subtracting the threshold voltage of the first transistor M1 from the voltage of the data signal DS during the data programming period is transferred to the first node N1, the threshold voltage of the first transistor M1 during the light emission period This is offset. Accordingly, the pixel PX may emit light uniformly with a luminance corresponding to the data signal DS regardless of the threshold voltage of the first transistor M1.

According to the pixel PX and its driving method described in FIGS. 2 and 3, whether or not a current path is formed in response to the emission control signal ESn may be determined. Accordingly, by adjusting the pulse duty of the emission control signal ESn, the emission time of each pixel PX can be adjusted.

For example, a period in which the emission control signal ESn has a gate-off voltage (eg, a period including an initialization period and a data programming period) is set as the non-emission period NEP of the pixel PX, and the emission control The period in which the signal ESn has the gate-on voltage may be set as the emission period EP of the pixel PX. Accordingly, when the gate-off voltage period (also referred to as “off duty”) of the emission control signal ESn is increased, the amount of emission of the pixel PX decreases as the non-emission period NEP of each pixel PX increases. do. Accordingly, an effect of reducing the luminance of the pixel PX can be obtained. Conversely, when the gate-on voltage period (also referred to as “on duty”) of the emission control signal ESn is increased, the emission period EP of each pixel PX increases, and the amount of emission of the pixel PX increases. . Accordingly, an effect of increasing the luminance of the pixel PX can be obtained.

4 is a graph showing a change in luminance according to a luminance level according to an embodiment of the present invention. For example, it shows a maximum luminance set at each luminance level according to an embodiment of the present invention. 5 is a graph illustrating a method of adjusting luminance of a display device according to an exemplary embodiment of the present invention.

First, referring to FIGS. 1 to 4, a maximum luminance for each luminance level may be set so that the luminance of the display area 100 gradually increases as the luminance level increases. According to an exemplary embodiment, the maximum luminance for each luminance level may be set so that natural luminance changes can be recognized according to the luminance level according to the human luminous characteristic.

In one embodiment, instead of storing gamma data for all selectable luminance levels, a reference for each of some sample luminance levels (eg, MTP tap points) (DBV[1] to DBV[L]) Gamma data may be set and stored, and reference gamma data for a corresponding luminance level may be obtained through gamma interpolation for the remaining luminance levels. Here, the reference gamma data corresponding to each luminance level may include gamma data set for each of predetermined reference grayscales for the corresponding luminance level. As an example, the reference gamma data may include gamma voltages for outputting data voltages corresponding to each reference gray level at each luminance level.

For example, when one of the sample luminance levels is selected, gamma voltages for reference gray scales stored for the selected sample luminance level may be output to the data driver 230. Meanwhile, when one of the remaining luminance levels for which gamma data is not previously stored is selected, a gamma voltage for each reference gradation corresponding to the luminance level is calculated through gamma interpolation, and the calculated gamma voltages are used in the data driver. It can be output to (230). Accordingly, the data driver 230 may generate data signals DS having voltages corresponding to respective luminance levels.

Then, the data driver 230 generates a data signal DS corresponding to the second image data DATA2 by using gamma voltages supplied from the luminance controller 250 and supplies the data to the pixels PX. Accordingly, the luminance of the display area 100 may be entirely adjusted according to each luminance level.

Depending on the embodiment, the display device 100 may include gamma data stored according to an optical compensation process performed for each sample luminance level. For example, the controller 240 may include a storage unit (memory) storing gamma data for each sample luminance level.

The optical compensation process refers to a deviation correction process for setting a gamma curve for maintaining stable display quality as a correlation between display luminance and gray scale. In order to remove or reduce the deviation between the display luminance and the actual display luminance according to the gray scale, correction of reference gamma data (eg, gamma voltages for the reference gray scales) may be repeatedly performed. The optical compensation process may be a multi-time programming (MTP) process that repeatedly corrects reference gamma data, but is not limited thereto.

According to an embodiment, in the present invention, as described above, the first luminance region and the second luminance region are divided around a predetermined reference luminance level, and the luminance of the display region 100 is determined in a different manner for each luminance region. Control. The reference luminance level refers to a specific sample luminance level that serves as a reference for classifying a first luminance region and a second luminance region among a plurality of sample luminance levels. That is, in describing an exemplary embodiment of the present invention, a sample luminance level, which is a reference for classifying a luminance region, will be referred to as a "reference luminance level" by distinguishing it from the remaining sample luminance levels.

For example, if the K-th (K is a natural number) sample luminance level (DBV[K]) with a maximum luminance of 100 nits is set as the reference luminance level, a luminance area with a maximum luminance lower than 100 nits is divided into the first luminance area. Thus, the luminance of the display area 100 can be controlled according to the first luminance control mode. And, if the luminance region having a maximum luminance of 100 nit or more (for example, when the maximum set luminance of the display device 10 is 300 nit and the corresponding luminance level is the Lth (L is a natural number greater than K) luminance level, the Kth sample luminance The luminance region from the level (DBV[K]) to the Lth sample luminance level (DBV[L]) is divided into a second luminance region, so that the luminance of the display region 100 can be controlled according to the second luminance control mode. have.

1 to 5, in the first luminance region, according to the first luminance control mode, as the luminance level increases, the off duty of the emission control signal ESn (that is, the gate-off voltage period) is decreased. The luminance of the area 100 may be increased. For example, the first luminance control mode may be an AID (AMOLED impulsive driving) mode (also referred to as a “pulse width modulation (PWM) mode”) driven by a duty adjustment method.

In an embodiment, in order to execute the first luminance control mode, an on/off duty (on duty and/or off duty) of the emission control signal ESn for each of the sample luminance levels of the first luminance region is set, and It is stored, and on/off duty may be obtained for the remaining luminance levels in the first luminance region through duty interpolation. Alternatively, in another embodiment, a plurality of luminance level groups are configured to include each sample luminance level, and on/off duty (on duty and/or off duty) of the emission control signal ESn for each luminance level group. Can also be set differentially.

Depending on the embodiment, in the first luminance region, a duty adjustment method and a gamma adjustment method may be applied together. For example, in the first luminance control mode, the duty adjustment method can be used as the main luminance control means, and the gamma adjustment method can be used as the auxiliary luminance control means. Accordingly, even in the first luminance region in which the driving current is low, the luminance of the display region 100 can be precisely controlled.

In the second luminance region, according to the second luminance control mode, gamma data may be adjusted so that gamma luminance increases as the luminance level increases. For example, the second luminance control mode may be a gamma mode driven by a gamma adjustment method.

Meanwhile, in the second luminance region, the on/off duty of the emission control signal ESn can be maintained at a constant value. For example, in the second luminance region, the on/off duty of the emission control signal ESn may be maintained at a constant value regardless of the luminance level.

Figure 6 It is a graph showing the difference in luminance between luminance levels in the second luminance region. For example, FIG. 6 shows changes in luminance according to gray levels at the lowest luminance level and the highest luminance level in the second luminance region.

4 to 6, the lowest luminance level of the second luminance region may be a reference luminance level positioned at the boundary of the first and second luminance regions, that is, the Kth sample luminance level DBV[K]. In addition, the highest luminance level of the second luminance region may be the Lth sample luminance level DBV[L], which is the last sample luminance level of the second luminance region.

In an embodiment, when the maximum set luminance of the display device 10 is 300 nits, a maximum gray scale, for example, a luminance corresponding to 255 gray scales, may be set to 300 nits at the Lth sample luminance level DBV[L]. In addition, at the Kth sample luminance level DBV[K], a luminance corresponding to 255 gray levels may be set to a luminance lower than 300 nit, for example, 100 nit. In addition, in each of the Lth sample luminance level DBV[L] and the Kth sample luminance level DBV[K], in addition to the highest grayscale, predetermined reference grayscales, such as 66, 100, and 155th grayscale, are Each target luminance can be set according to a desired gamma curve.

According to an embodiment, in the second luminance region, gamma data may be set for each of the sample luminance levels DBV[K] to DBV[L] so that a target luminance can be expressed in each reference gray scale. In addition, for other luminance levels between the sample luminance levels DBV[K] to DBV[L], gamma data for each reference gray level may be obtained through gamma interpolation. That is, in the second luminance region, the luminance of the display region 100 is controlled through a gamma adjustment method, and accordingly, a maximum luminance and a gamma curve corresponding thereto can be obtained for each luminance level.

7 is a waveform diagram of a light emission control signal ESn for explaining a duty adjustment method applied to a first luminance region. According to an embodiment, in FIG. 7, as a luminance level belonging to a first luminance region, a sample luminance level that is one level lower than a reference luminance level, for example, light emission generated at the K-1th sample luminance level (DBV[K-1]) Control signal (ESn), The duty adjustment method will be described in comparison with the emission control signal ESn generated at the reference luminance level, that is, the Kth sample luminance level DBV[K].

4 to 7, in the first luminance region, the luminance of the display region 100 is controlled by differentially setting the on/off duty ratio of the emission control signal ESn according to each luminance level. I can. For example, the off duty of the light emission control signal ESn corresponding to the K-1th sample luminance level DBV[K-1] is the light emission control signal corresponding to the Kth sample luminance level DBV[K] ( ESn) may be set larger than the off duty.

Meanwhile, as the off duty of the emission control signal ESn increases, the on duty of the emission control signal ESn decreases. For example, the on duty of the emission control signal ESn at the K-1th sample luminance level DBV[K-1] is the emission control signal ESn at the Kth sample luminance level DBV[K] It may be set smaller than the on duty of. Accordingly, at the K-1th sample luminance level DBV[K-1], the emission time of the pixels PX decreases in response to the increase in off-duty, and the Kth sample luminance level DBV[K] ), the luminance of the pixels PX may be lowered overall.

8 is a graph showing a deviation between an actual luminance measured in the first luminance region and a target luminance according to sample luminance levels of a first luminance region set according to an embodiment of the present invention.

4 to 8, in the first luminance region, each sample luminance level may be set at points corresponding to different on-duties. For example, K-1 sample luminance levels may be set in the first luminance region. On the other hand, when including the K-1 sample luminance levels and a reference luminance level used for gamma and/or duty interpolation in the first luminance region, that is, the K-th sample luminance level (DBV[K]), The first luminance region can also be viewed as including K sample luminance levels.

In an embodiment, sample luminance levels of the first luminance region may be arranged at a predetermined interval or more in consideration of memory capacity or efficiency of an optical compensation process. As an example, the sample luminance levels of the first luminance region may be distributed and positioned at a point where an on duty (emission duty) corresponding to each luminance level differs by at least 10% or more. In addition, since the driving current decreases as the luminance level decreases, the sample luminance levels may be arranged in the first luminance region in consideration that more precise correction may be required for on-duty and/or gamma data.

For example, in the first luminance region, four sample luminance levels are arranged at points where the on duty including the reference luminance level is 15%, 30%, 60% and 100%, respectively, and each of the sample luminance levels The on duty and/or gamma data for the remaining luminance levels may be calculated by interpolating the on duty and/or gamma data set for each. In this case, the K-1th sample luminance level (DBV[K-1]) is located at a point where the on duty is set to 60%, and the Kth sample luminance level (DBV[K]) is set to be 100% on duty. It can be located at the point where it becomes.

In describing the exemplary embodiment of the present invention, "on duty" may be based on an on duty in the second luminance region (for example, a maximum light emission time that can be set for each pixel PX). For example, an on duty of 100% means having the same on duty as in the second luminance region, and an on duty of 60% corresponds to approximately 60% of the on duty in the second luminance region. It can mean having an on duty.

As in the above-described embodiment, as a result of arranging four sample luminance levels at points where the on duty is 15%, 30%, 60%, and 100%, respectively, and measuring the actual luminance displayed in the first luminance region, the first The luminance inversion between the last interpolation interval of the luminance region, that is, between the K-1th sample luminance level (DBV[K-1]) and the Kth sample luminance level (DBV[K]) whose on duty is 60% and 100%, respectively It can be seen that the phenomenon occurs. As an example, as a result of measuring the actual luminance change according to the luminance level for each of 11 gradations (11G) and 23 gradations (23G), the K-1th sample luminance level (DBV[K-1]) and the Kth sample Between the luminance levels (DBV[K]), the actual luminance is measured higher than the target luminance, and the deviation between the actual luminance and the target luminance is the most deepened at a point close to the Kth sample luminance level (DBV[K]). I can confirm. On the other hand, at the Kth sample luminance level (DBV[K]), since gamma data is set to represent a predetermined target luminance according to an optical compensation process such as an MTP process, at the Kth sample luminance level (DBV[K]) The measured actual luminance may be a desired target luminance or a luminance close thereto.

The above-described luminance inversion phenomenon is the last interpolation interval of the first luminance region, that is, the reference luminance level (the Kth sample luminance level (DBV[K])) and the sample luminance level immediately before it (the K-1th sample luminance level (DBV)). [K-1])) can be deepened as the interval between them increases. Due to the luminance reversal phenomenon, natural luminance adjustment according to the luminance level in the first luminance region may be difficult, and image quality characteristics of the display device 10 may be deteriorated.

9 is a waveform diagram of a light emission control signal ESn for explaining the luminance reversal phenomenon of FIG. 8. 10 is a graph showing on/off characteristics of a transistor (eg, a driving transistor of the pixel PX) for explaining the luminance inversion phenomenon of FIG. 8.

8 to 10, as the off duty of the light emission control signal ESn increases, the off bias of the driving transistor increases, and accordingly, the driving current increases. For example, the driving transistor has a different threshold voltage Vth in the on/off state, and as the off period increases, the deviation of the threshold voltage Vth may increase. Accordingly, as the off duty of the emission control signal ESn increases, the driving current increases. Accordingly, a luminance reversal phenomenon may occur in the vicinity of the Kth sample luminance level DBV[K] at which the off duty of the emission control signal ESn starts to increase due to an increase in the off-bias of the driving transistor.

For example, a luminance reversal phenomenon may occur in a luminance level range in which the duty difference from the Kth sample luminance level DBV[K] is within approximately 10%. For example, a luminance inversion phenomenon may occur between a luminance level corresponding to 95% of on-duty and a K-th sample luminance level DBV[K].

On the other hand, in the remaining section of the first luminance region (eg, a luminance level range in which the on duty is set to 90% or less), the amount of reduction in luminance due to a decrease in the emission time of the pixels PX than the increase in luminance due to an increase in the off-bias As this becomes larger, as the luminance level decreases, the actual luminance may also decrease. That is, the luminance reversal phenomenon due to an increase in the off-bias of the driving transistor may occur around the boundary between the first luminance region and the second luminance region, that is, at luminance levels immediately before the Kth sample luminance level DBV[K].

11 and 12 are graphs showing actual luminance measured in the first luminance region according to sample luminance levels in the first luminance region set according to another embodiment of the present invention.

First, referring to FIG. 11, in this embodiment, the width of the last interpolation section of the first luminance region is reduced so that the on-duty difference is within 10%. For example, a reference luminance level for the boundary between a first luminance region and a second luminance region, that is, a point at which the on duty is 90% or more compared to the Kth sample luminance level (DBV[K]). A K-1th sample luminance level (DBV[K-1]) may be disposed at a point corresponding to the 95% range. Accordingly, the interval between the Kth sample luminance level DBV[K] and the K-1th sample luminance level DBV[K-1] may be reduced to a range in which the on-duty difference is within 10%. For example, the K-1th sample luminance level DBV[K-1] may be disposed at a point in which the on duty is set to 95%.

In one embodiment, by changing the setting position of at least one sample luminance level belonging to the first luminance region, in particular, the K-1th sample luminance level (DBV[K-1]) compared to the embodiment of FIG. 1 It is possible to decrease the width of the last interpolation section of the luminance region. For example, four sample luminance levels can be placed at points where the on duty is 15%, 45%, 95%, and 100%, respectively.

Alternatively, in another embodiment, through the addition of the sample luminance level, an additional sample luminance level may be disposed at a point corresponding to the on-duty range of 90% to 95%. For example, as in the embodiment of FIG. 8, four sample luminance levels are arranged at points where the on duty is 15%, 30%, 60%, and 100%, respectively, and one at the point where the on duty is 95%. Additional sample luminance levels can be arranged.

That is, in the present embodiment, in the first luminance region in which the duty adjustment method is adjusted, the position of at least one sample luminance level is changed so that at least one sample luminance level is disposed at a point where the on duty is 90% or more, or a new sample You can add a luminance level. Accordingly, the width of the last interpolation section of the first luminance region can be reduced so that the on-duty difference is within approximately 10%.

As described above, according to an embodiment of the present invention, the sample luminance levels set in the first luminance region are compared to the reference luminance level (Kth sample luminance level DBV[K]) of the pixels PX. It may include at least one sample luminance level (eg, K-1th sample luminance level DBV[K-1]) set to decrease the light emission time by within 10%. Accordingly, it is possible to prevent a luminance reversal phenomenon occurring at the boundary of the first luminance region adjacent to the second luminance region.

For example, a K-1th sample luminance level (DBV[K-1]) is disposed at a point corresponding to the on-duty 90% to 95% range, and the K-1th sample luminance level (DBV[K-1 ]), it is possible to set gamma data for the reference gradations so that the actual luminance is closer to the target luminance through an MTP process or the like. Accordingly, in and around the K-1th sample luminance level DBV[K-1], the actual luminance may be corrected according to the target luminance.

Referring to FIG. 12, a K-1th sample luminance level DBV[K-1] is placed at an on-duty 95% point, and a predetermined gray scale, for example, 11 gray scales 11G and 23 corresponding to a low gray scale range. As a result of measuring the actual luminance change according to the luminance level for each of the gradations 23G, it can be seen that the luminance reversal phenomenon is suppressed and the gamma curve is improved.

According to the above-described embodiment, the luminance increases according to the off-bias characteristic of the driving transistor in the boundary between the luminance regions where the off-duty of the emission control signal ESn starts to increase, for example, in the last interpolation period of the first luminance region. Can be compensated for through gamma adjustment. Accordingly, by preventing or attenuating the luminance reversal phenomenon that may occur between luminance levels in a partial section of the first luminance region (for example, the last interpolation section), the luminance of the display region can be more effectively and naturally adjusted over the entire luminance level. I can.

13 is a block diagram illustrating a brightness control unit 250 and a storage unit 260 according to an embodiment of the present invention. Depending on the embodiment, the brightness control unit 250 and the storage unit 260 may be located in the control unit 240 of FIG. 1, but are not limited thereto.

Referring to FIG. 13, the brightness control unit 250 may include a mode selection unit 252, a duty control unit 254 and a gamma control unit 256. The luminance control unit 250 may receive the luminance selection signal SEL and output the second control signal CONT2 and the reference gamma data VGAM in response thereto. On the other hand, for convenience of explanation, in FIG. 13, each of the driving blocks constituting the luminance control unit 250, that is, the mode selection unit 252, the duty control unit 254, and the gamma control unit 256 are all separately illustrated. , The mode selection unit 252, the duty control unit 254 and/or the gamma control unit 256 may be merged into one driving block and configured.

The mode selector 252 determines a luminance level corresponding to the input luminance selection signal SEL, and selects one of the first and second luminance control modes according to the luminance region to which the luminance level belongs. For example, the mode selector 252 may include section information on the first and second luminance regions, and select any one of the first and second luminance control modes using the section information. have. For example, when it is determined that the luminance level corresponding to the luminance selection signal SEL belongs to the first luminance region, the mode selector 252 selects the first luminance control mode, and the luminance selection signal SEL When it is determined that the luminance level corresponding to is belonging to the second luminance region, the second luminance control mode may be selected. Operations of the duty control unit 254 and the gamma control unit 256 may be controlled in response to the first or second luminance control mode selected by the mode selection unit 252.

The duty control unit 254 controls the emission time of the pixels PX to decrease by corresponding to each luminance level in response to the first luminance control mode, and controls the pixels in response to the second luminance control mode. The emission time of (PX) can be controlled to be maintained at a predetermined reference time. To this end, the duty controller 254 may output a light emission start signal EFLM having a pulse width corresponding to the light emission time of the pixels PX. For example, in the first luminance control mode, the duty control unit 254 adjusts and outputs the pulse width of the emission start signal EFLM so that the off duty of the emission control signal ESn increases as the luminance level decreases, In the second luminance control mode, a light emission start signal EFLM having a constant pulse width (for example, an initially set pulse width) can be output so that the off duty of the light emission control signal ESn is kept constant regardless of the luminance level. have. The light emission start signal EFLM is included in the second control signal CONT2 and supplied to the light emission control driver 220 and is used to generate the light emission control signal ESn.

The gamma control unit 256 outputs reference gamma data VGMA according to each luminance level corresponding to the luminance selection signal SEL with reference to the storage unit 260 in the first and second luminance control modes. . For example, in the first and second luminance control modes, the gamma control unit 256 may differentially adjust and output gamma data VGMA of reference grayscales according to respective luminance levels. As an example, the gamma control unit 250 outputs reference gamma data VGMA for controlling the emission luminance of the pixels PX to increase as the luminance level increases in the second luminance control mode, and in the first luminance control mode. As the luminance level increases, the gamma data VGMA of the reference gray scales may be adjusted and output so that the emission luminance of the pixels PX according to the complex adjustment of duty and gamma increases. The reference gamma data VGMA is supplied to the data driver 230 and used to generate the data signal DS.

The storage unit 260 includes gamma data corresponding to the reference luminance level (the K-th sample luminance level DBV[K]), and at least one sample luminance level belonging to the first luminance region (for example, first to K-th luminance level). A first gamma data set including gamma data corresponding to each of the first sample luminance levels DBV[1] to DBV[K-1], and at least one sample luminance level belonging to the second luminance region (for example, A second gamma data set including gamma data corresponding to each of the K+1 to L-th sample luminance levels DBV[K+1] to DBV[L] may be stored, for example, the storage unit 260. Is, for each of the reference luminance level (the Kth sample luminance level DBV[K]) and the sample luminance levels of the first and second luminance regions, reference gamma voltages corresponding to the reference gray levels are repeatedly stored. It may contain a point programming (MTP) register.

According to an embodiment, the first gamma data set stored in the storage unit 260 has an emission time of less than 10% of the pixels PX compared to the reference luminance level (Kth sample luminance level DBV[K]). It may include gamma data corresponding to at least one sample luminance level set to decrease by a range of. As an example, the first gamma data set is the K-1th sample luminance level DBV in which the emission time of the pixels PX is set to 95% compared to the reference luminance level (the Kth sample luminance level DBV[K]). Gamma data corresponding to [K-1]) may be included.

14 is a flowchart illustrating a method of adjusting luminance of the display device 10 according to an exemplary embodiment of the present invention. In describing the embodiment of FIG. 14, redundant descriptions of parts that are similar or identical to those of the above-described embodiments will be omitted.

Referring to FIG. 14, a method for adjusting luminance of the display device 10 according to an embodiment of the present invention includes a standard luminance level setting step (ST10), a gamma data storage step (ST20), and a luminance selection signal input step (ST30). , A first or second luminance control mode execution step ST40 and a luminance control step ST50 of the display area may be included.

<ST10: Standard luminance level setting step>

First, a predetermined reference luminance level (for example, a K-th sample luminance level (DBV[K])), at least one standard luminance level lower than the reference luminance level, so that the luminance of the display device 10 can be set step by step ( For example, first to K-1th sample luminance levels (DBV[1] to DBV[K-1]), and at least one standard luminance level higher than the reference luminance level (for example, K+1th to A plurality of standard luminance levels including the Lth sample luminance level (DBV[K] to DBV[L]) may be set. According to an embodiment, the standard luminance levels may be set to include at least one luminance level set so that the emission time of the pixels PX decreases by within 10% compared to the reference luminance level.

<Gamma data storage step (ST20)>

Next, gamma data for each of the standard luminance levels may be set and stored. For example, through the MTP process, gamma data for reference gray levels may be set for each of the standard luminance levels. In addition, the set gamma data may be stored in the storage unit 260.

<Luminance selection signal input step (ST30)>

Next, the luminance selection signal SEL may be input to the luminance control unit 250. According to an embodiment, the luminance selection signal SEL may be a control signal input to the luminance controller 250 in response to an initial setting or a luminance level selected according to a user input.

<First or second luminance control mode execution step (ST40)>

Next, a luminance level corresponding to the input luminance selection signal SEL is determined, and accordingly, the first or second luminance control mode is executed. For example, when the luminance level corresponding to the luminance selection signal SEL belongs to the first luminance region, the first luminance control mode is executed, and the luminance level corresponding to the luminance selection signal SEL is in the second luminance region. If so, the second luminance control mode can be executed.

<Level of brightness adjustment of the display area (ST50)>

Next, the brightness of the display area 100 is adjusted according to the executed first or second brightness control mode. For example, in the first luminance control mode, the luminance of the display area 100 is adjusted by differentially adjusting the emission time and gamma data of the pixels PX according to each luminance level, and in the second luminance control mode, The luminance of the display area 100 may be adjusted by differentially adjusting only gamma data according to the luminance level of.

Through the above-described process, the luminance of the display area 100 may be adjusted according to each luminance level.

Although the technical idea of the present invention has been described in detail according to the above-described embodiments, it should be noted that the above embodiments are for the purpose of explanation and not for the limitation thereof. In addition, those of ordinary skill in the technical field of the present invention will appreciate that various modifications are possible within the scope of the technical idea of the present invention.

The scope of the present invention is not limited to the content described in the detailed description of the specification, but should be defined by the claims. In addition, the meaning and scope of the claims, and all changes or modified forms derived from the concept of equivalents thereof should be construed as being included in the scope of the present invention.

10: display device 100: display area
200: display driver 210: scan driver
220: light emission control driving unit 230: data driving unit
240: control unit 250: luminance control unit
260: storage

Claims (16)

A display area including pixels connected to scan lines, emission control lines, and data lines; And
A display driver configured to drive the pixels in response to input image data, timing signals, and luminance selection signals,
The display driver,
A first luminance region and a second luminance region are divided based on a predetermined reference luminance level, and a first luminance control mode and a second luminance control mode are used in the first luminance region and the second luminance region, respectively. A luminance control unit for controlling luminance; And
Gamma data corresponding to the reference luminance level, a first gamma data set corresponding to sample luminance levels of the first luminance region, and a second gamma data set corresponding to sample luminance levels of the second luminance region are stored Includes wealth,
The first gamma data set includes gamma data corresponding to a sample luminance level set such that the emission time of the pixels is reduced within a range of 10% or less compared to the reference luminance level. The method of claim 1,
The brightness control unit,
In the first luminance control mode, the luminance of the display region is controlled by adjusting light emission times of the pixels and gamma data of reference grayscales according to respective luminance levels belonging to the first luminance region,
In the second luminance control mode, the luminance of the display region is controlled by adjusting gamma data of the reference grayscales according to respective luminance levels belonging to the second luminance region. The method of claim 1,
The brightness control unit,
A mode selector for selecting one of the first and second luminance control modes in response to the luminance selection signal;
A duty control unit controlling the emission time of the pixels to be reduced by corresponding to each luminance level in the first luminance control mode, and controlling the emission time of the pixels to be maintained at a predetermined time in the second luminance control mode; And
And a gamma control unit configured to output reference gamma data according to each luminance level corresponding to the luminance selection signal with reference to the storage unit in the first and second luminance control modes. The method of claim 3,
The mode selector includes section information on the first luminance region and the second luminance region, and selects any one of the first and second luminance control modes by using the section information. The method of claim 3,
The duty control unit outputs a light emission start signal having a pulse width corresponding to light emission time of the pixels. The method of claim 5,
The display device further comprising: a light emission control driver sequentially supplying light emission control signals to the light emission control lines in response to the light emission start signal. The method of claim 6,
The duty control unit, in the first luminance control mode, adjusts and outputs a pulse width of the emission start signal such that an off duty of the emission control signal increases as the luminance level decreases. The method of claim 7,
The duty control unit, in the second luminance control mode, outputs the light emission start signal so that the off duty of the light emission control signal is kept constant regardless of the luminance level. The method of claim 6,
The display device further comprising: a scan driver sequentially supplying scan signals to the scan lines so as to be synchronized with the gate-off period of the emission control signal. The method of claim 3,
The gamma control unit differentially adjusts and outputs gamma data of reference grayscales according to the luminance level in the first and second luminance control modes. The method of claim 10,
The display device further comprising: a data driver generating data signals corresponding to the input image data using gamma data of the reference grayscales and supplying the data signals to the data lines. The method of claim 10,
The storage unit may repetitively store reference gamma voltages corresponding to the reference grayscales for each of the reference luminance level, sample luminance levels of the first luminance region, and sample luminance levels of the second luminance region. A display device comprising a point programming (MTP) register. The method of claim 1,
The sample luminance levels of the first luminance region include a sample luminance level in which the emission time of the pixels is set in a range of 90% to 95% compared to the reference luminance level. Setting standard luminance levels including a predetermined reference luminance level, at least one standard luminance level lower than the reference luminance level, and at least one standard luminance level higher than the reference luminance level;
Setting and storing gamma data for reference gray scales for each of the standard luminance levels;
Executing a first brightness control mode or a second brightness control mode in response to the brightness selection signal; And
In the first luminance control mode, the gamma data and the emission time of pixels are adjusted according to each luminance level to adjust the luminance of the display area, and in the second luminance control mode, the gamma data is adjusted according to each luminance level. And adjusting the luminance of the display area,
The standard luminance levels include a sample luminance level set such that the emission time of the pixels decreases by a range within 10% compared to the reference luminance level. The method of claim 14,
In the first luminance control mode, as the luminance level decreases, the emission time of the pixels decreases,
In the second luminance control mode, the luminance control method of the display device, wherein the emission time of the pixels is kept constant regardless of the luminance level. The method of claim 14,
In the step of setting the standard luminance levels, a luminance level at which the emission time of the pixels is set in a range of 90% to 95% compared to the reference luminance level is set to one of the standard luminance levels. .

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