KR102423587B1 - Organic light emitting diode display device - Google Patents

Abstract

In a driving method of an organic light emitting diode display including a plurality of pixels, an off ratio, which is a ratio of a non-emission period to a frame time, is determined according to a dimming level, a black gray voltage is adjusted according to the determined off ratio, and the plurality of pixels are framed. A plurality of pixels are driven to emit light based on a plurality of gray voltages including a black gray voltage adjusted during a light emission period during a non-emission period corresponding to the determined OFF ratio during the frame time. Accordingly, power consumption may be reduced in the organic light emitting diode display to which the AID dimming technology is applied.

Description

A driving method of an organic light emitting display device, and an organic light emitting display device {ORGANIC LIGHT EMITTING DIODE DISPLAY DEVICE}

The present invention relates to a display device, and more particularly, to an organic light emitting display device and a driving method thereof.

An organic light emitting diode display displays an image using an organic light emitting diode (OLED) that emits light by recombination of electrons and holes. Such an organic light emitting display device has a fast response speed and is driven with low power consumption, so it is in the spotlight as a next-generation display.

A dimming technique for changing all grayscale voltages using a gray scale at a predetermined luminance level (eg, a maximum luminance level) in order to implement a dimming mode of the organic light emitting diode display, one frame A dimming technique for controlling the length of a light emitting section (or a non-emission section) in the interior has been developed. On the other hand, the dimming technology for controlling the length of the light emitting section may be called AID (AMOLED Impulsive Driving) dimming technology. Therefore, even at a high dimming level (low luminance level), panel mura due to a driving current deviation may not occur.

However, since the driving current is not reduced in the AID dimming technology, it is preferable to apply a power consumption reduction method suitable for the AID dimming technology.

SUMMARY OF THE INVENTION One object of the present invention is to provide a method of driving an organic light emitting diode display capable of reducing power consumption in an organic light emitting diode display to which AMOLED Impulsive Driving (AID) dimming technology is applied.

Another object of the present invention is to provide an organic light emitting diode display capable of reducing power consumption in an organic light emitting diode display to which AID dimming technology is applied.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and may be variously expanded without departing from the spirit and scope of the present invention.

In order to achieve one object of the present invention, in the method of driving an organic light emitting diode display including a plurality of pixels according to embodiments of the present invention, an OFF ratio, which is a ratio of a non-emission period to a frame time, is determined according to a dimming level, , a black gradation voltage is adjusted according to the determined off-ratio, the plurality of pixels do not emit light during the non-emission period corresponding to the determined off-ratio during the frame time, and the adjusted black during the light emitting period of the frame time The plurality of pixels are driven to emit light based on a plurality of gray voltages including the gray voltage.

In an embodiment, the black gradation voltage may decrease as the off ratio increases.

In an exemplary embodiment, the amount of decrease in the black gray voltage may be determined within a range in which the luminance of a pixel to which the reduced black gray voltage is applied is maintained.

In an embodiment, the plurality of pixels may include PMOS transistors. When the black gray voltage is adjusted, a gate high voltage for turning off the PMOS transistors may be adjusted.

In an exemplary embodiment, the gate high voltage may be decreased by an amount equal to the decrease amount of the black gray voltage.

In an embodiment, enable information indicating whether to adjust the black gradation voltage in the black gradation voltage setting register, threshold information indicating at least one off ratio threshold defining a plurality of off ratio ranges, and a unit of the black gradation voltage Decrease amount information indicating the decrease amount may be stored.

In an embodiment, when the enable information is checked to adjust the black gray voltage according to the determined off ratio, and the enable information indicates that the black gray voltage is adjusted, the determined off ratio is used as the off ratio An off-ratio range to which the determined off-ratio belongs from among the plurality of off-ratio ranges is determined compared with a threshold, and the black gradation voltage by a multiplication value of the unit reduction amount indicated by the reduction amount information and a coefficient corresponding to the determined off-ratio range This can be reduced.

In an exemplary embodiment, other grayscale voltages other than the black grayscale voltage among the plurality of grayscale voltages may be decreased in proportion to a decrease amount of the black grayscale voltage.

In an embodiment, at least some of the gray voltages other than the black gray voltage among the plurality of gray voltages may not decrease even if the black gray voltage is decreased.

In an embodiment, the light emitting section and the non-emission section may be divided by a light emission control signal applied to the plurality of pixels.

In order to achieve another object of the present invention, in an organic light emitting diode display according to embodiments of the present invention, an OFF ratio, which is a ratio of a non-emission period to a frame time, is determined according to a display panel including a plurality of pixels and a dimming level. and adjusting the black gray voltage according to the determined off ratio, the plurality of pixels do not emit light during the non-emission period corresponding to the determined off ratio during the frame time, and during the light emission period of the frame time, the adjusted and a driver driving the plurality of pixels to emit light based on a plurality of gray voltages including a black gray voltage.

In an embodiment, the driving unit includes an off-ratio determiner that determines the off-ratio according to the dimming level, a voltage adjuster that adjusts the black gray voltage according to the determined off-ratio, and the adjusted black gray voltage. a grayscale voltage generator generating the plurality of grayscale voltages, a scan driver applying a scan signal to the plurality of pixels, and the adjusted black as a data voltage to each of the plurality of pixels while the scan signal is applied a data driver that applies a gray voltage corresponding to image data among the plurality of gray voltages including a gray voltage, and generates a light emission control signal based on the determined off-ratio, and sends the light emission control signal to the plurality of pixels It may include a light emission control unit for applying the.

In an embodiment, the voltage adjuster may decrease the black grayscale voltage as the off ratio increases.

In an embodiment, the voltage adjuster may determine the amount of decrease in the black gray voltage within a range in which luminance of a pixel to which the reduced black gray voltage is applied as the data voltage is maintained.

In an embodiment, the plurality of pixels may include PMOS transistors, and the voltage controller may further adjust a gate high voltage for turning off the PMOS transistors when the black gray voltage is adjusted.

In an embodiment, the voltage adjuster may decrease the gate high voltage by an amount equal to the decrease amount of the black gray voltage.

In an embodiment, the driving unit may include enable information indicating whether to adjust the black gray voltage, threshold information indicating at least one off ratio threshold defining a plurality of off ratio ranges, and a unit decrease amount of the black gray voltage. It may further include a black gradation voltage setting register for storing the indicated reduction amount information.

In an embodiment, the voltage adjuster may check the enable information, and when the enable information indicates that the black gray voltage is adjusted, compare the determined off ratio with the off ratio threshold to determine the plurality of off ratios. An off-ratio range to which the determined off-ratio belongs may be determined among the ranges, and the black gray voltage may be reduced by a multiplication value of the unit reduction amount indicated by the reduction amount information and a coefficient corresponding to the determined off-ratio range.

In an exemplary embodiment, the gray voltage generator may generate the plurality of gray voltages such that other gray voltages other than the black gray voltage among the plurality of gray voltages are reduced in proportion to a decrease amount of the black gray voltage.

In an exemplary embodiment, the gray voltage generator may generate the plurality of gray voltages so that at least some of the gray voltages other than the black gray voltage are not reduced even if the black gray voltage is reduced. have.

A method of driving an organic light emitting display device, and an organic light emitting display device according to embodiments of the present invention, by adjusting a black grayscale voltage according to an AMOLED Off Ratio (AOR) determined during AMOLED Impulsive Driving (AID) dimming, Power consumption can be reduced without changing the black luminance (luminance of about 0).

In addition, the method of driving the organic light emitting display device and the organic light emitting display device according to embodiments of the present invention may further reduce power consumption by further adjusting the gate high voltage to correspond to the adjusted black gray scale voltage.

However, the effects of the present invention are not limited to the above-mentioned effects, and may be variously expanded without departing from the spirit and scope of the present invention.

1 is a flowchart illustrating a method of driving an organic light emitting diode display according to example embodiments.
2 is a diagram illustrating an example of a light emitting section and a non-emission section in one frame.
3 is a diagram illustrating an example of black luminance according to black gray voltages and off ratios.
4 is a flowchart illustrating a method of driving an organic light emitting diode display according to example embodiments.
5 is a circuit diagram illustrating an example of a pixel of an organic light emitting diode display according to exemplary embodiments.
6 is a diagram illustrating an example of current consumption when the black gray voltage and the gate high voltage are not adjusted and when the voltage is adjusted.
7 is a flowchart illustrating a method of driving an organic light emitting diode display according to example embodiments.
FIG. 8 is a diagram for explaining an example of a black gradation voltage setting register included in an organic light emitting diode display according to embodiments of the present invention.
9 is a diagram for explaining an example of adjusting a black grayscale voltage according to an off-ratio range in an organic light emitting diode display according to embodiments of the present invention.
10 is a block diagram illustrating an organic light emitting diode display according to example embodiments.
11 is a block diagram illustrating an electronic device including an organic light emitting diode display according to example embodiments.

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

1 is a flowchart illustrating a method of driving an organic light emitting display device according to embodiments of the present disclosure, FIG. 2 is a diagram illustrating an example of a light emitting section and a non-emission section in one frame, and FIG. 3 is a black gray voltage It is a diagram illustrating an example of black luminance according to s and off ratios.

Referring to FIG. 1 , in the method of driving an organic light emitting diode display according to embodiments of the present invention, an OFF ratio, which is a ratio of a non-emission period to a frame time, is determined according to a dimming level (or a luminance level) ( S110 ). As described above, the organic light emitting diode display according to embodiments of the present invention can emit light at a desired dimming level or a desired luminance level by adjusting the length of the non-emission section, that is, the length of the light emitting section, which is an AID (Active Matrix (AMOLED) Organic Light Emitting Diode) Impulsive Driving) It can be called dimming technology. In addition, the off ratio, which is a ratio of the non-emission period to the frame time, may be referred to as an AMOLED Off Ratio (AOR).

In an embodiment, the light emitting section and the non-emission section may be divided by a light emission control signal applied to a plurality of pixels included in the organic light emitting diode display. For example, as shown in FIG. 2 , a period in which the emission control signal EM has a low level within a frame time corresponding to one frame is defined as the emission period EP, and the emission control signal EM A section in which ) has a high level may be defined as a non-emission section (NEP). In the light emitting section EP, a current path from a high power voltage to a low power voltage through the organic light emitting diode is formed in each pixel, and each pixel can emit light. In the non-emission period NEP, since a current path from the high power supply voltage to the low power supply voltage is not formed, each pixel may not emit light.

In another embodiment, the light emitting period and the non-emission period may be divided by adjusting at least one of the high power supply voltage and the low power supply voltage supplied to the plurality of pixels. For example, during the light emission period, the high power supply voltage and the low power supply voltage have a constant voltage difference, so that a current path from the high power supply voltage to the low power supply voltage is formed so that each pixel can emit light. During the non-emission period, when the voltage level of the low power supply voltage rises to the voltage level of the high power supply voltage, a current path from the high power supply voltage to the low power supply voltage is not formed, so that each pixel may not emit light. .

The black gradation voltage is adjusted according to the determined off-ratio (S130). Here, the black gradation voltage may be a gradation voltage of 0 gradation indicating the lowest luminance (or 0 luminance). Meanwhile, in the organic light emitting diode display according to embodiments of the present invention, the plurality of pixels may include PMOS transistors, and the black gray voltage may turn off a driving transistor implemented as a PMOS transistor of each pixel. It may be the highest voltage among the plurality of gray voltages (eg, 0 to 255 gray voltages).

The black gray voltage may decrease as the off ratio increases. Also, the reduction amount of the black gray voltage may be determined within a range in which the luminance of the pixel to which the reduced black gray voltage is applied is substantially maintained at 0 (eg, about 0 nt). That is, when the off-ratio is increased and the length of the light emitting period within the frame time is decreased, the luminance of the pixel to which the black gray voltage is applied may be maintained at about 0 nt even if the black gray voltage is decreased. For example, referring to FIG. 3 , in an organic light emitting diode display using a black gray voltage of about 6.4 V, even when the black gray voltage is reduced to about 5.6 V, when the off ratio (AOR) is about 22.09% or more, it is about 5.6 A pixel to which the black gradation voltage of V is applied may have a luminance of about 0 nt, and even if the black gradation voltage is reduced to about 5.5 V, when the off ratio (AOR) is about 36.80% or more, the black of about 5.5 V A pixel to which the gray voltage is applied may have a luminance of about 0 nt, and even if the black gray voltage is reduced to about 5.4 V, when the off ratio (AOR) is about 80.59% or more, the black gray voltage of about 5.4 V is applied A pixel may have a luminance of about 0 nt. Accordingly, in the organic light emitting diode display having a black luminance as shown in FIG. 3 , when the off ratio AOR is about 22.09%, the black grayscale voltage may be reduced to about 5.6 V, and the off ratio AOR may be about 22.09%. When it is 36.08%, the black gray voltage may be reduced to about 5.5 V, and when the off ratio AOR is about 80.59%, the black gray voltage may be reduced to about 5.4 V. Meanwhile, when the black gray voltage is reduced, power consumption of the organic light emitting diode display, such as power consumption for generating a plurality of gray voltages including the black gray voltage, and power consumption for charging/discharging a data line, may be reduced.

Meanwhile, in an exemplary embodiment, other grayscale voltages other than the black grayscale voltage among the plurality of grayscale voltages may be reduced in proportion to a decrease amount of the black grayscale voltage. For example, the grayscale voltage generator (or gamma voltage generator) included in the organic light emitting diode display generates other grayscale voltages by dividing the reduced black grayscale voltage, thereby reducing the grayscale in proportion to the decrease in the black grayscale voltage. voltages can be generated. In another exemplary embodiment, some or all of the gray voltages other than the black gray voltage among the plurality of gray voltages may not be decreased even if the black gray voltage is decreased. For example, the gray voltage generator generates substantially the same reference gamma voltage before and after adjusting the black gray voltage, and generates the other gray voltages based on the reference gamma voltage. It is possible to generate grayscale voltages that do not exist.

The organic light emitting diode display drives a plurality of pixels based on the determined off-ratio and the adjusted black gradation voltage ( S150 ). That is, in the organic light emitting diode display, the plurality of pixels do not emit light during the non-emission period corresponding to the determined off ratio during the frame time and include the adjusted black grayscale voltage during the light emission period of the frame time. The plurality of pixels may be driven to emit light based on grayscale voltages of .

As described above, in the method of driving an organic light emitting diode display according to embodiments of the present invention, by adjusting the black gray voltage according to the off ratio corresponding to the dimming level of the AID dimming, the black luminance (the luminance of about 0 nt) is ), power consumption of the organic light emitting diode display may be reduced.

4 is a flowchart illustrating a method of driving an organic light emitting diode display according to embodiments of the present invention, FIG. 5 is a circuit diagram illustrating an example of a pixel of an organic light emitting display according to embodiments of the present invention, and FIG. 6 is a diagram illustrating an example of current consumption when the black gray voltage and the gate high voltage are not adjusted and when the voltage is adjusted.

Referring to FIG. 4 , in the method of driving an organic light emitting diode display according to embodiments of the present invention, an OFF ratio, which is a ratio of a non-emission section to a frame time, is determined according to a dimming level (or a luminance level) ( S210 ), and the A black gradation voltage is adjusted according to the determined off-ratio (S230), a gate high voltage is adjusted according to the adjusted black gradation voltage (S250), the determined off-ratio, the adjusted black gradation voltage, and the adjusted gate A plurality of pixels may be driven based on the high voltage (S270). In the method of driving the organic light emitting diode display of FIG. 4 , the gate high voltage may be further adjusted compared to the driving method of the organic light emitting display of FIG. 1 .

A plurality of pixels included in the organic light emitting diode display according to embodiments of the present invention may include PMOS transistors, and when the black gray voltage is adjusted, a gate high voltage for turning off the PMOS transistors is adjusted. can be For example, as shown in FIG. 5 , each pixel 300 receives the data voltage transmitted by the switching transistor TSWS and the switching transistor TSWS for transmitting the data voltage in response to the scan signal SCAN. The storage capacitor CST to store, the driving transistor TDR for generating a driving current based on the data voltage stored in the storage capacitor CST, and the organic light emitting diode EL in response to the emission control signal EM. . Here, the transistors TSWS, TDR, and TEM included in each pixel 300 may be implemented as PMOS transistors. Also, when the black gray voltage VBLACK decreases as the off ratio increases, the gate high voltage VGH for turning off the transistors TSWS, TDR, and TEM may also decrease. For example, the scan signal SCAN may have a gate low voltage VGL for turning on the switching transistor TSWS or a gate high voltage VGH for turning off the switching transistor TSWS. can At this time, the gate high voltage VGH of the scan signal SCAN does not generate a leakage current through the switching transistor TSWS even when the black gray voltage VBLACK, which is the highest voltage among the plurality of gray voltages, is applied to the data line. It should be high enough to avoid Meanwhile, when the black gray voltage VBLACK, which is the highest voltage among the plurality of gray voltages, is reduced, even if the gate high voltage VGH of the scan signal SCAN is reduced to correspond to the reduced black gray voltage VBLACK. A leakage current through the switching transistor TSWS may not be generated. That is, when the black gray voltage VBLACK is decreased, even if the gate high voltage VGH is decreased, the pixel 300 may not malfunction. In an embodiment, the gate high voltage VGH may be decreased by the same amount of decrease as the decrease of the black gray voltage VBLACK. In another exemplary embodiment, the decrease amount of the gate high voltage VGH may be different from the decrease amount of the black gray voltage VBLACK. Meanwhile, although an example of a pixel structure is illustrated in FIG. 5 , the pixel of the organic light emitting diode display according to embodiments of the present invention is not limited to the pixel structure illustrated in FIG. 5 and may have various structures.

As described above, when the black gray voltage VBLACK is decreased as well as the gate high voltage VGH is also decreased, the organic light emitting diode display includes power consumption for generating the gate high voltage VGH and power consumption for charging and discharging the scan line. power consumption can be further reduced. For example, as shown in FIG. 6 , in the organic light emitting diode display using the black gray voltage VBLACK of about 6.4 V and the gate high voltage VGH of about 6.6 V, the off ratio AOR is about 41.27%. When the black gray voltage VBLACK is reduced to about 6.2 V and the gate high voltage VGH is reduced to about 6.4 V, the pixels of the organic light emitting display display the highest gray level (eg, 255 gray). When emitting light, the battery current (IBAT) is reduced from about 98.4 mA to about 97.8 mA, reducing the current consumption by about 0.61%, and when the pixels emit light at the lowest gradation (eg 0 gradation), the battery current (IBAT) is It decreased from about 46 mA to about 45.2 mA, reducing the current consumption by about 1.74%. In addition, when the off ratio AOR is about 80.59% and the black gray voltage VBLACK is reduced to about 6V and the gate high voltage VGH is reduced to about 6.2V, the pixels of the organic light emitting diode display have the highest values. When light is emitted with gradation (eg, 255 gradation), the battery current (IBAT) is reduced from about 66.7 mA to about 64.8 mA, reducing current consumption by about 2.85%, and pixels are at the lowest gradation (eg, 0 gradation) In the case of light emission, the battery current (IBAT) decreased from about 46.2 mA to about 45.2 mA, reducing the current consumption by about 2.16%. As described above, as the off-ratio AOR increases, the black gray voltage VBLACK and the gate high voltage VGH decrease, so that the current consumption of the organic light emitting diode display is reduced, and thus the power consumption of the organic light emitting display is decreased. can be reduced.

As described above, in the method of driving an organic light emitting diode display according to embodiments of the present invention, by adjusting the black gray voltage according to the off ratio corresponding to the dimming level of the AID dimming, the black luminance (the luminance of about 0 nt) is ), power consumption of the organic light emitting diode display may be reduced. Also, in the method of driving an organic light emitting diode display according to embodiments of the present invention, power consumption may be further reduced by further adjusting the gate high voltage to correspond to the adjusted black gray voltage.

7 is a flowchart illustrating a method of driving an organic light emitting diode display according to embodiments of the present invention, and FIG. 8 is a diagram illustrating an example of a black gradation voltage setting register included in the organic light emitting diode display according to embodiments of the present invention. FIG. 9 is a diagram for explaining an example of adjusting a black grayscale voltage according to an off-ratio range in an organic light emitting diode display according to embodiments of the present invention.

Referring to FIG. 7 , in the method of driving an organic light emitting diode display according to embodiments of the present invention, enable information, threshold information, and reduction amount information for setting a black gray voltage adjustment operation are included in the organic light emitting diode display. It may be stored in the black gradation voltage setting register (S410). In an embodiment, the enable information may indicate whether to adjust the black gradation voltage, the threshold information may indicate at least one off-ratio threshold defining a plurality of off-ratio ranges, and the reduction amount information may include: It may represent a unit decrease amount of the black gray voltage. For example, as shown in FIG. 8 , the black gray voltage setting register may store 1-bit enable information (ENABLE_INFO[0]) and enable information (ENABLE_INFO[0]) having a value of '0'. ]) indicates that the black gray voltage is not adjusted, and the enable information ENABLE_INFO[0] having a value of '1' may indicate that the black gray voltage is adjusted. Also, the black gray voltage setting register may store at least one off-ratio threshold as the threshold information, and may store four off-ratio thresholds AOR_THRESHOLD1, AOR_THRESHOLD2, AOR_THRESHOLD3, and AOR_THRESHOLD4 in the example of FIG. 8 . In addition, in the example of FIG. 8 , the black gradation voltage setting register may store 2-bit reduction amount information (DELTA_INFO[1:0]), and reduction amount information having a value of '00' (DELTA_INFO[1:0]) may indicate that the unit decrement amount of the black gradation voltage is about 0.05 V, and the decrease amount information (DELTA_INFO[1:0]) having a value of '01' indicates that the unit decrement amount of the black gradation voltage is about 0.1 V The decrease amount information DELTA_INFO[1:0] having a value of '10' may indicate that the unit decrease amount of the black gray voltage is about 0.2 V, and the decrease amount information DELTA_INFO[ 1:0]) may indicate that the unit decrease amount of the black gray voltage is about 0.3 V. Meanwhile, the enable information, the threshold information, and the decrease amount information stored in the black gray voltage setting register may be written during manufacturing of the organic light emitting diode display or updated during driving of the organic light emitting display apparatus.

In the organic light emitting diode display, a non-in-off ratio of a non-emission period to a frame time is determined according to a dimming level (or a luminance level) ( S420 ), and together with the determined off-ratio, the in-off ratio stored in the black gradation voltage setting register is determined. The black grayscale voltage may be adjusted based on the enable information, the threshold information, and the decrease amount information (S430).

In an embodiment, the enable information stored in the black gray voltage setting register may be checked ( S440 ). When the enable information has a value of '0' indicating that the black gray voltage is not adjusted (S440: NO), the black gray voltage and the gate high voltage may not be adjusted even if the off ratio is changed. When the enable information has a value of '1' indicating that the black gray voltage is adjusted (S440: YES), the off ratio range to which the determined off ratio belongs based on the threshold information stored in the black gray voltage setting register is is determined ( S450 ), and the black gradation voltage may be decreased based on the determined off-ratio range and the reduction amount information stored in the black gradation voltage setting register ( S460 ). In an embodiment, an off-ratio range to which the determined off-ratio belongs is determined from among a plurality of off-ratio ranges by comparing the determined off-ratio with the off-ratio threshold value indicated by the threshold information, and the black gradation voltage is the reduction amount information It may be reduced by a multiplication value of the indicated unit decrease amount and a coefficient corresponding to the determined off-ratio range.

For example, as shown in FIG. 9 , when the off ratio determined according to the dimming level is smaller than the first off ratio threshold AOR_THRESHOLD1 , the black gray voltage may be maintained as the basic black gray voltage DEF_VBLACK. That is, a coefficient corresponding to the first off-ratio range smaller than the first off-ratio threshold AOR_THRESHOLD1 may be 0. In addition, when the determined off-ratio is greater than or equal to the first off-ratio threshold AOR_THRESHOLD1 and falls within a second off-ratio range smaller than the second off-ratio threshold AOR_THRESHOLD2, the coefficient corresponding to the second off-ratio range is 1 , and the black gradation voltage may be decreased from the basic black gradation voltage DEF_VBLACK by a unit decrease amount ΔV indicated by the decrease amount information. In addition, when the determined off-ratio is greater than or equal to the second off-ratio threshold AOR_THRESHOLD2 and falls within a third off-ratio range smaller than the third off-ratio threshold AOR_THRESHOLD3, the coefficient corresponding to the third off-ratio range is 2 , and the black gradation voltage may be decreased by twice the unit decrease amount ΔV from the basic black gradation voltage DEF_VBLACK. In addition, when the determined off-ratio is greater than or equal to the third off-ratio threshold AOR_THRESHOLD3 and falls within a fourth off-ratio range smaller than the fourth off-ratio threshold AOR_THRESHOLD4, the coefficient corresponding to the fourth off-ratio range is 3 , and the black gradation voltage may be reduced from the basic black gradation voltage DEF_VBLACK by three times the unit decrement amount ΔV indicated by the decrease amount information. Also, when the determined off-ratio belongs to a fifth off-ratio range that is greater than or equal to the fourth off-ratio threshold AOR_THRESHOLD4, a coefficient corresponding to the fifth off-ratio range may be 4, and the black grayscale voltage is the basic black It may be reduced from the grayscale voltage DEF_VBLACK by four times the unit decrease amount ΔV indicated by the decrease amount information.

Also, in the organic light emitting diode display according to the embodiments of the present invention, the gate high voltage is further adjusted according to the adjusted black gray voltage ( S470 ), the determined off ratio, the adjusted black gray voltage, and the adjustment A plurality of pixels included in the organic light emitting diode display may be driven based on the applied gate high voltage (S480). Accordingly, power consumption of the organic light emitting diode display according to embodiments of the present invention may be reduced.

10 is a block diagram illustrating an organic light emitting diode display according to example embodiments.

Referring to FIG. 10 , an organic light emitting diode display 500 according to embodiments of the present invention includes a display panel 510 including a plurality of pixels PX, and a plurality of pixels ( A driving unit 520 for driving PX) may be included.

The display panel 510 may include a plurality of pixels PX arranged in a matrix form having a plurality of rows and a plurality of columns. Each pixel PX may include an organic light emitting diode, and the display panel 510 may be an organic light emitting diode display panel. Also, each pixel PX may include PMOS transistors.

The driver 520 may drive the plurality of pixels PX so that the plurality of pixels PX of the display panel 510 emit light. In addition, the driver 520 determines an off ratio, which is a ratio of a non-emission period to a frame time, according to the dimming level, adjusts the black gray voltage V0 according to the determined off ratio, and the plurality of pixels PX A plurality of gray voltages V0, V1, and V255 that do not emit light during the non-emission period corresponding to the determined off ratio during the frame time and include the black gray voltage V0 adjusted during the light emission period of the frame time. The plurality of pixels PX may be driven to emit light based on . In an exemplary embodiment, the driver 520 is a gray voltage generator (or gamma voltage generator) 530 that generates a plurality of gray voltages V0, V1, and V255, based on the image data RGB and RGB′. to select the plurality of grayscale voltages V0, V1, and V255 and provide the selected grayscale voltage as the data voltage VDATA to the plurality of pixels PX, the data driver 540 and the plurality of pixels PX The scan driver 550 providing the scan signal SCAN, the light emission control unit 560 providing the emission control signal EM to the plurality of pixels PX, the grayscale voltage generator 530 , and the data driver 540 ), a control unit 570 for controlling the scan driver 550 and the light emission control unit 560 may be included. Also, the control unit 570 may include an off ratio determining unit 580 and a voltage adjusting unit 590 . In an embodiment, the control unit 570 may further include a black gradation voltage setting register 595 .

The off ratio determiner 580 may determine the off ratio according to the dimming level. In an embodiment, the off ratio determiner 580 may receive a dimming signal SDIM indicating the dimming level (or luminance level) from an external device, and as the dimming level indicated by the dimming signal SDIM increases, The off ratio may be determined to increase (or as the luminance level decreases). The off-ratio determiner 580 may provide an off-ratio signal SAOR representing the determined off-ratio to the light emission control unit 560 , and the light emission control unit 560 responds to the off-ratio signal SAOR to a light emission control signal The duty cycle of (EM) can be adjusted. Also, the off-ratio determiner 580 may further provide an off-ratio signal SAOR indicating the determined off-ratio to the voltage adjuster 590 .

The voltage adjuster 590 may adjust the black grayscale voltage V0 according to the determined off-ratio indicated by the off-ratio signal SAOR. In an embodiment, the voltage adjuster 590 provides the reference black voltage REF_BLACK adjusted according to the determined OFF ratio to the gray voltage generator 530 , and the gray voltage generator 530 provides the adjusted reference black voltage. An adjusted black grayscale voltage V0 may be generated based on the voltage REF_BLACK. However, the method in which the voltage adjuster 590 adjusts the black gradation voltage V0 according to embodiments of the present invention is not limited thereto. The voltage adjuster 590 may decrease the black gradation voltage V0 as the off ratio increases. In addition, the voltage adjuster 590 controls the black gray voltage V0 within a range in which the luminance of the pixel PX to which the reduced black gray voltage V0 is applied as the data voltage VDATA is substantially maintained. reduction can be determined. Accordingly, in the organic light emitting diode display 500 , power consumption may be reduced while black luminance is not changed.

In an embodiment, the voltage controller 590 may further adjust a gate high voltage for turning off the PMOS transistors included in the plurality of pixels PX when the black gray voltage V0 is adjusted. have. For example, the voltage adjuster 590 may decrease the gate high voltage by an amount equal to the decrease amount of the black gray voltage V0.

Also, according to an embodiment, the voltage adjuster 590 may adjust the black gray voltage V0 by using the black gray voltage setting register 595 . For example, the black gray voltage setting register 595 includes enable information indicating whether the black gray voltage V0 is adjusted, threshold information indicating at least one off ratio threshold defining a plurality of off ratio ranges, and black gray level Decrease amount information indicating a unit decrease amount of the voltage V0 may be stored. In this case, the voltage adjusting unit 590 checks the enable information and, when the enable information indicates that the black gray voltage V0 is adjusted, compares the determined off-ratio with the off-ratio threshold to obtain the plurality of An off-ratio range to which the determined off-ratio belongs may be determined among the off-ratio ranges, and the black gray voltage may be reduced by a multiplication value of the unit reduction amount indicated by the reduction amount information and a coefficient corresponding to the determined off-ratio range.

Meanwhile, although FIG. 9 shows an example in which the off ratio determining unit 580, the voltage adjusting unit 590, and the black gradation voltage setting register 595 are included in the control unit 570, embodiments of the present invention are not limited thereto. does not

The gray voltage generator 530 may generate a plurality of gray voltages V0, V1, and V255 including the adjusted black gray voltage V0, and the scan driver 550 generates a plurality of pixels PX. can apply the scan signal SCAN to the , and the data driver 540 applies the adjusted black gray voltage V0 as the data voltage VDATA to each pixel PX while the scan signal SCAN is applied. A grayscale voltage selected from among the plurality of grayscale voltages V0, V1, and V255 may be applied. Meanwhile, the controller 570 receives the image data RGB received from the external device, performs predetermined image processing on the image data RGB, and transfers the image data RGB′ on which the image processing is performed to the data driver. 540 may be provided. The data driver 540 may select a grayscale voltage for each pixel PX based on the image data RGB′ on which the image processing is performed. The emission control unit 560 may generate the emission control signal EM based on the determined off-ratio and apply the emission control signal EM to the plurality of pixels PX. Accordingly, the plurality of pixels PX do not emit light during the non-emission period corresponding to the determined off-ratio, and a plurality of grayscale voltages V0 including the black grayscale voltage V0 adjusted during the light emission period; V1, V255) can emit light.

In an exemplary embodiment, the gray voltage generator 530 may select the black gray voltage V0 from other gray voltages V1 and V255 except for the black gray voltage V0 among the plurality of gray voltages V0, V1, and V255. ), a plurality of gray voltages V0, V1, and V255 may be generated to be reduced in proportion to the decrease amount. For example, when the black gray voltage V0 is reduced, the gray voltage generator 530 divides the reduced black gray voltage V0 or the reduced reference black voltage REF_BLACK to set other gray voltages V1, By generating V255), it is possible to generate the grayscale voltages V1 and V255 reduced in proportion to the decrease amount of the black grayscale voltage V0. In another exemplary embodiment, the gray voltage generator 530 may include at least a portion of the other gray voltages V1 and V255 except for the black gray voltage V0 among the plurality of gray voltages V0, V1, and V255. A plurality of grayscale voltages V0, V1, and V255 may be generated so that the voltage V0 is not decreased even if the voltage V0 is decreased. For example, the gray voltage generator 530 generates substantially the same reference gamma voltage before and after the black gray voltage V0 is adjusted, and generates different gray voltages V1 and V255 based on the reference gamma voltage. Accordingly, it is possible to generate grayscale voltages V1 and V255 that are not reduced even when the black grayscale voltage V0 is reduced.

As described above, in the organic light emitting diode display 500 according to embodiments of the present invention, black luminance (about 0 nt) is adjusted by adjusting the black gradation voltage V0 according to the off ratio corresponding to the dimming level of the AID dimming. ), power consumption of the organic light emitting diode display 500 may be reduced. In addition, in the organic light emitting diode display 500 according to embodiments of the present invention, the gate high voltage is further adjusted to correspond to the adjusted black gray scale voltage V0, so that the organic light emitting diode display 500 consumes more power. can be reduced.

11 is a block diagram illustrating an electronic device including an organic light emitting diode display according to example embodiments.

Referring to FIG. 11 , the electronic device 800 includes a processor 810 , a memory device 820 , a storage device 830 , an input/output device 840 , a power supply 850 , and an organic light emitting display device 860 . can do. The electronic device 800 may further include various ports capable of communicating with a video card, a sound card, a memory card, a USB device, or the like, or communicating with other systems.

The processor 810 may perform certain calculations or tasks. According to an embodiment, the processor 810 may be a microprocessor, a central processing unit (CPU), an application processor (AP), or the like. The processor 810 may be connected to other components through an address bus, a control bus, and a data bus. Depending on the embodiment, the processor 810 may also be connected to an expansion bus such as a Peripheral Component Interconnect (PCI) bus.

The memory device 820 may store data necessary for the operation of the electronic device 800 . For example, the memory device 820 may include Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Flash Memory, Phase Change Random Access Memory (PRAM), and Resistance (RRAM). Non-volatile memory devices such as Random Access Memory), Nano Floating Gate Memory (NFGM), Polymer Random Access Memory (PoRAM), Magnetic Random Access Memory (MRAM), Ferroelectric Random Access Memory (FRAM), etc. and/or Dynamic Random Access (DRAM) memory), static random access memory (SRAM), and a volatile memory device such as mobile DRAM.

The storage device 830 may include a solid state drive (SSD), a hard disk drive (HDD), a CD-ROM, and the like. The input/output device 840 may include input means such as a keyboard, a keypad, a touch pad, a touch screen, and a mouse, and an output means such as a speaker and a printer. The power supply 850 (eg, a battery) may supply power required for the operation of the electronic device 800 .

The organic light emitting diode display 860 may use AID dimming technology. Also, the organic light emitting diode display 860 may reduce power consumption without changing the black luminance by adjusting the black grayscale voltage according to the off ratio corresponding to the dimming level of the AID dimming. In addition, the organic light emitting diode display 860 may further reduce power consumption by further adjusting the gate high voltage to correspond to the adjusted black gray scale voltage.

According to an embodiment, the electronic device 800 includes a digital TV (Digital Television), a 3D TV, a personal computer (PC), a home electronic device, a laptop computer, a tablet computer (Table Computer), a mobile phone ( Mobile phone, smart phone, personal digital assistant (PDA), portable multimedia player (PMP), digital camera (Digital Camera), music player (Music Player), portable game console It may be any electronic device including the organic light emitting display device 860 such as a portable game console and navigation.

The present invention can be applied to any organic light emitting display device and an electronic device including the same. For example, the present invention can be applied to TV, digital TV, 3D TV, PC, home electronic device, notebook computer, tablet computer, mobile phone, smart phone, PDA, PMP, digital camera, music player, portable game console, navigation, etc. have.

Although the above has been described with reference to the embodiments of the present invention, those skilled in the art can variously modify and change the present invention within the scope without departing from the spirit and scope of the present invention described in the claims below. You will understand that you can.

500: organic light emitting display device
510: display panel
520: driving unit
580: off non-determining part
590: voltage regulator
530: gradation voltage generator
550: scan driver
540: data driver
560: light emission control

Claims (20)

A method of driving an organic light emitting diode display including a plurality of pixels, the method comprising:
determining an off-ratio, which is a ratio of a non-emission period to a frame time, according to a dimming level;
adjusting a black gradation voltage according to the determined off-ratio; and
The plurality of pixels do not emit light during the non-emission period corresponding to the determined OFF ratio during the frame time, and emit light based on a plurality of gray voltages including the adjusted black gray voltage during the light emission period of the frame time. and driving the plurality of pixels to do so. The method of claim 1 , wherein the black gray voltage decreases as the off ratio increases. The method of claim 2 , wherein the amount of the decrease in the black gray voltage is determined within a range in which a luminance of a pixel to which the reduced black gray voltage is applied is maintained at zero. The method of claim 1 , wherein the plurality of pixels include PMOS transistors, and the method of driving the organic light emitting display device comprises:
and adjusting a gate high voltage for turning off the PMOS transistors when the black gray voltage is adjusted. 5 . The method of claim 4 , wherein the gate high voltage is decreased by an amount equal to a decrease amount of the black gray scale voltage. The method of claim 1,
Enable information indicating whether the black gradation voltage is adjusted in the black gradation voltage setting register, threshold information indicating at least one off-ratio threshold defining a plurality of off-ratio ranges, and decrement amount information indicating a unit decrease amount of the black gradation voltage The method of driving an organic light emitting display device, characterized in that it further comprises the step of storing. The method of claim 6 , wherein the adjusting of the black gradation voltage according to the determined off-ratio comprises:
checking the enable information;
determining an off-ratio range to which the determined off-ratio belongs from among the plurality of off-ratio ranges by comparing the determined off-ratio with the off-ratio threshold when the enable information indicates that the black gray voltage is adjusted; and
and reducing the black gradation voltage by a multiplication value of the unit reduction amount indicated by the reduction amount information and a coefficient corresponding to the determined off-ratio range. The method of claim 1 , wherein other grayscale voltages other than the black grayscale voltage among the plurality of grayscale voltages are reduced in proportion to a decrease amount of the black grayscale voltage. The method of claim 1 , wherein at least some of the gray voltages other than the black gray voltage among the plurality of gray voltages are not reduced even if the black gray voltage is reduced. The method of claim 1 , wherein the emission section and the non-emission section are divided by a light emission control signal applied to the plurality of pixels. a display panel including a plurality of pixels; and
an off ratio that is a ratio of a non-emission section to a frame time is determined according to a dimming level, and a black gray voltage is adjusted according to the determined off ratio, and the plurality of pixels have the ratio corresponding to the determined off ratio during the frame time An organic light emitting diode display comprising: a driver configured to emit light based on the plurality of gray voltages including the adjusted black gray voltage during the light emission period during the frame time and to drive the plurality of pixels to emit light. 12. The method of claim 11, wherein the driving unit,
an off ratio determiner configured to determine the off ratio according to the dimming level;
a voltage adjusting unit for adjusting the black gray voltage according to the determined off ratio;
a grayscale voltage generator configured to generate the plurality of grayscale voltages including the adjusted black grayscale voltage;
a scan driver for applying a scan signal to the plurality of pixels;
a data driver that applies a grayscale voltage corresponding to image data among the plurality of grayscale voltages including the adjusted black grayscale voltage as a data voltage to each of the plurality of pixels while the scan signal is applied; and
and a light emission controller configured to generate a light emission control signal based on the determined off-ratio and apply the light emission control signal to the plurality of pixels. The organic light emitting diode display of claim 12 , wherein the voltage adjuster decreases the black grayscale voltage as the off ratio increases. The organic light emitting display of claim 13 , wherein the voltage adjuster determines the amount of decrease in the black gray voltage within a range in which luminance of a pixel to which the reduced black gray voltage is applied is maintained as the data voltage. Device. 13. The method of claim 12, wherein the plurality of pixels comprises PMOS transistors;
and the voltage adjuster further adjusts a gate high voltage for turning off the PMOS transistors when the black gray voltage is adjusted. The organic light emitting diode display of claim 15 , wherein the voltage adjuster decreases the gate high voltage by an amount equal to a decrease amount of the black gray voltage. The method of claim 12, wherein the driving unit,
Black gray voltage storing enable information indicating whether the black gray voltage is adjusted, threshold information indicating at least one off ratio threshold defining a plurality of off ratio ranges, and reduction amount information indicating a unit decrease amount of the black gray voltage The organic light emitting diode display further comprising a setting register. 18. The method of claim 17, wherein the voltage regulator,
Check the enable information,
when the enable information indicates that the black gray voltage is adjusted, comparing the determined off-ratio with the off-ratio threshold to determine an off-ratio range to which the determined off-ratio belongs among the plurality of off-ratio ranges;
and decreasing the black gradation voltage by a multiplication value of the unit reduction amount indicated by the reduction amount information and a coefficient corresponding to the determined off-ratio range. 13. The method of claim 12, wherein the gray voltage generator is configured to generate the plurality of gray voltages such that other gray voltages other than the black gray voltage among the plurality of gray voltages are reduced in proportion to a decrease amount of the black gray voltage. an organic light emitting display device. 13. The method of claim 12, wherein the gray voltage generator is configured to generate the plurality of gray voltages so that at least some of the gray voltages other than the black gray voltage are not reduced even if the black gray voltage is reduced. An organic light emitting display device, characterized in that.

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