KR20190078181A - Display device and method of driving thereof - Google Patents

Abstract

A display device capable of reducing the power consumption according to the present invention comprises: a display panel displaying an image and including a gate line and data line; and a panel driving unit driving the display panel by applying a signal to the display panel and supplying a reference voltage (DDVDH) with a level determined according to gradation of the image displayed on the display panel.

Description

DISPLAY APPARATUS AND METHOD OF DRIVING THEREOF [0002]

The present invention relates to a display device capable of reducing power consumption and a driving method thereof.

Recently, with the development of multimedia, the importance of display devices is increasing. In response to this, display devices such as a liquid crystal display device, a plasma display device, and an organic light emitting display device have been commercialized. Of these display devices, an organic light emitting display device has been widely used at present because it has a high response speed, a high luminance, and a good viewing angle.

Particularly, since such a display device can be reduced in size and weight, it is usefully applied to portable information devices such as mobile phones, tablet computers, and notebook computers. However, since the portable information device is supplied with power through a limited power supply device such as a battery, it is necessary to reduce the power consumption as much as possible in order to use the information device for a long time. However, there has been a limit in reducing power consumption in a liquid crystal display device or an organic light emitting display device which are mainly used at present.

It is an object of the present invention to provide a display device and a driving method thereof that can reduce power consumption by supplying not only a data voltage but also a reference voltage at a low voltage in realizing a low gray level image.

A display device according to the present invention includes a display panel for displaying an image and including a gate line and a data line, a driving circuit for driving the display panel by applying a signal to the display panel, And a panel driver for supplying the reference voltage DDVDH.

The panel driver includes a gate driver for applying a gate signal to the gate line, a data driver for applying a data voltage to the data line, a timing controller for driving the gate driver and the data driver, A power supply voltage unit for generating a voltage and driving the gate driver, the data driver and the timing controller to generate a plurality of reference voltages, and a controller for controlling the power supply voltage according to the control signal, A gamma reference voltage unit for selecting one reference voltage among a plurality of reference voltages input from the plurality of reference gamma voltage tables and selecting one reference gamma voltage table among a plurality of reference gamma voltage tables according to the selected reference voltage, .

Wherein the voltage control unit comprises: a comparator for generating a plurality of gradation reference levels having different levels and for comparing the gradation of the image data input from the external system with a set value; and a control unit for generating and outputting a control signal according to the comparison result And a control signal generator.

The power supply voltage unit includes a level determination unit for analyzing and determining a plurality of gradation reference levels according to a control signal of the voltage control unit and a reference voltage generation unit for generating a plurality of reference voltages having different voltage levels according to the analysis of the level determination unit Wherein the plurality of gradation reference levels correspond one-to-one with a plurality of reference voltages.

The gamma reference voltage unit may include a reference voltage selector for selecting a reference voltage corresponding to a gradation reference level of an image from a plurality of reference voltages input from a power supply voltage unit according to a control signal, A memory for storing a gamma voltage table and a plurality of reference gamma voltage tables for selecting one of a plurality of reference gamma voltage tables according to a selected reference voltage outputted from the reference voltage selector, And a gamma reference voltage generator for outputting a reference gamma voltage table selected by the gamma reference voltage selector to a data driver based on a gamma reference voltage, wherein the plurality of reference gamma voltage tables correspond to a plurality of reference voltages, Respectively.

According to another aspect of the present invention, there is provided a method of driving a display device, the method comprising: analyzing image data from an external system to determine a level of a plurality of gradation reference levels corresponding to the gradation of the image data; A step of generating a plurality of reference voltages corresponding to the plurality of gradation reference levels, a step of selecting a reference voltage corresponding to a gradation reference level of the image data among the plurality of reference voltages, Selecting one reference gamma voltage table in the gamma voltage table, and converting the pixel data into a data voltage using the selected reference gamma voltage table and supplying the data voltage to the data line.

In the present invention, the image data is analyzed to generate a plurality of reference voltages having different levels according to the gradation of the image data. Then, a low level reference voltage is applied to the low gradation image and a high level reference voltage is applied to the high gradation image Is applied.

When displaying a low-grayscale image and a high-grayscale image in a display device of a general structure, the data voltage applies a low voltage and a high voltage through the data lines, respectively, but the reference voltage applied to the gamma reference voltage portion, The power consumption is increased due to the use of the high voltage reference voltage when the low gradation image is implemented, since it is always the same regardless of the gradation of the image.

On the other hand, in the present invention, a low-level reference voltage is applied to a low-gradation image and a high-level reference voltage is supplied to an image of a high gradation, so that power consumption can be reduced in implementing a low- .

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically shows a display device according to the present invention. Fig.
2 is a block diagram showing the structure of a voltage control unit of a display device according to the present invention;
3 is a block diagram showing a structure of a power supply voltage part of a display device according to the present invention;
4 is a block diagram showing the structure of a gamma reference voltage part of a display device according to the present invention;
5 is a flow chart showing a method of driving a display device according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims.

The shapes, sizes, ratios, angles, numbers, and the like disclosed in the drawings for describing the embodiments of the present invention are illustrative, and thus the present invention is not limited thereto. Like reference numerals refer to like elements throughout the specification. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. In the case where the word 'includes', 'having', 'done', etc. are used in this specification, other parts can be added unless '~ only' is used. Unless the context clearly dictates otherwise, including the plural unless the context clearly dictates otherwise.

In interpreting the constituent elements, it is construed to include the error range even if there is no separate description.

In the case of a description of the positional relationship, for example, if the positional relationship between two parts is described as 'on', 'on top', 'under', and 'next to' Or " direct " is not used, one or more other portions may be located between the two portions.

In the case of a description of a temporal relationship, for example, if the temporal relationship is described by 'after', 'after', 'after', 'before', etc., May not be continuous unless they are not used.

The first, second, etc. are used to describe various components, but these components are not limited by these terms. These terms are used only to distinguish one component from another. Therefore, the first component mentioned below may be the second component within the technical spirit of the present invention.

It is to be understood that each of the features of the various embodiments of the present invention may be combined or combined with each other, partially or wholly, technically various interlocking and driving, and that the embodiments may be practiced independently of each other, It is possible.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a structure of a display device according to the present invention.

1, the display apparatus according to the present invention includes a display panel 100 and a panel driver 200 for driving the display panel 100. [ Although the organic light emitting display panel 100 is illustrated as the display panel 100 in the drawing, the present invention is not limited to the organic light emitting display panel but may be applied to various display panels such as a liquid crystal display panel. Therefore, hereinafter, the display panel 100 will be described as an organic electroluminescence display panel, but this description may be applied to other display panels such as a liquid crystal display panel and the like.

The display panel 100 includes a plurality of sub-pixels SP. The plurality of sub-pixels SP are formed in a region defined by a plurality of gate lines GL and a plurality of data lines DL which intersect with each other. A plurality of driving voltage lines PL1 are formed in the display panel 100 in parallel with the plurality of data lines DL and supplied with the driving voltage from the panel driving unit 200. [

Each of the plurality of sub-pixels SP may be any one of a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel. One unit pixel for displaying one image may include an adjacent red sub-pixel, a green sub-pixel, a blue sub-pixel and a white sub-pixel, or may include a red sub-pixel, a green sub-pixel and a blue sub-pixel. Each of the plurality of sub-pixels SP includes an organic light emitting diode OLED and a pixel circuit PC.

The organic light emitting diode OLED is connected between the pixel circuit PC and the second power supply line PL2 and emits a monochromatic color light by emitting light in proportion to an amount of data current supplied from the pixel circuit PC . The organic light emitting diode OLED includes an anode electrode (or a pixel electrode) connected to the pixel circuit PC, a cathode electrode (or a reflective electrode) connected to the second driving power supply line PL2, an anode electrode And a light emitting layer formed between the cathode electrodes and emitting light of any one of red, green, blue, and white, and outputting the light. Here, the light emitting layer may have a structure of a hole transporting layer / an organic light emitting layer / an electron transporting layer or a structure of a hole injecting layer / a hole transporting layer / an organic light emitting layer / an electron transporting layer / an electron injecting layer. Furthermore, the light emitting layer may further include a functional layer for improving the luminous efficiency and / or lifetime of the organic light emitting layer.

The pixel circuit PC responds to the gate signal GS of the gate-on voltage level supplied from the panel driver 200 to the gate line GL and supplies the data voltage Vdd supplied from the panel driver 200 to the data line DL (Vdata) to the organic light emitting diode OLED. To this end, the pixel circuit PC includes a switching transistor, a driving transistor, and at least one capacitor formed on a substrate by a thin film transistor forming process.

In the case where the display panel 100 is a liquid crystal display panel, the display panel 100 is provided with a plurality of red (R, G, B) subpixels SP, each of which is defined by a plurality of gate lines GL and data lines DL. Red) color filter, a green (green) color filter, and a blue (blue) color filter are formed. Further, a white sub-pixel in which no color filter is formed can be provided. Each of the plurality of sub-pixels SP includes a liquid crystal layer. The liquid crystal layer is disposed between the pixel electrode and the common electrode so that the arrangement of the liquid crystal molecules in the liquid crystal layer is changed according to the voltage applied to the pixel electrode and the light transmittance of the liquid crystal layer So that the image can be displayed.

The panel driver 200 includes a timing controller 220, a gate driver 230, a data driver 240, a power voltage unit 250, a gamma reference voltage unit 260, and a power controller 270 .

The timing controller 220 controls the timing of driving the gate driver 230 and the data driver 240 according to a timing synchronization signal TSS input from an external system body (not shown) or a graphic card (not shown) do. That is, the timing controller 220 generates a gate control signal GCS and a data control signal DCS based on a timing synchronization signal TSS such as a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a dot clock Controls the driving timing of the gate driving unit 230 through the gate control signal GCS and controls the driving timing of the data driving unit 240 through the data control signal DCS so as to be synchronized with the timing.

The power supply voltage unit 250 generates a voltage and supplies the generated voltage to the timing control unit 220, the gate driving unit 230 and the data driving unit 240 so that the timing control unit 220, the gate driving unit 230, the data driving unit 240 And generates a reference voltage DDVDH and supplies the reference voltage DDVDH to the gamma reference voltage unit 260. [

The power control unit 270 analyzes the gradation of input image data RGB and outputs a control signal according to the analyzed gradation. The power control unit 270 analyzes the gradation of the image into a plurality of gradation levels, and generates and outputs control signals for each gradation level.

The power supply voltage unit 250 generates a plurality of reference voltages DDVDH1, DDVDH2,..., DDVDHn having different levels according to a control signal input from the power control unit 270, Supply. The gradation reference level of the image of the power control unit 270 and the reference voltages DDVDH1, DDVDH2, ..., DDVDHn generated by the power supply voltage unit 250 may correspond one to one. Therefore, the lowest gradation reference level of the image corresponds to the lowest level reference voltage among the plurality of reference voltages DDVDH1, DDVDH2 ... DDVDHn generated by the power supply control unit 270, Corresponding to the reference voltage of the highest level among the plurality of reference voltages DDVDH1, DDVDH2 ... DDVDHn generated by the power supply control unit 270. [

The gamma reference voltage generator 260 generates one reference voltage DDVDH of the reference voltages DDVDH1, DDVDH2, ..., DDVDHn input from the power supply voltage generator 250 according to a control signal input from the voltage controller 270, Selects one reference gamma voltage table T corresponding to the reference voltage DDVDH selected from a plurality of reference gamma voltage tables stored in the memory, and provides the selected reference gamma voltage table T to the data driver 240. [ At this time, when the reference voltages DDVDH_1, DDVDH_2,..., DDVDH_n having n levels are supplied from the power supply voltage unit 250, n gamma reference voltage tables T1, T2. ... Tn.

At this time, the first reference voltage DDVDH_1 corresponding to the lowest gradation reference level corresponds to the first reference gamma voltage table T1 formed at the lowest voltage level, and the nth reference voltage DDVDH_n corresponding to the highest gradation reference level And corresponds to the n-th reference gamma voltage table Tn created at the maximum voltage level. The reference voltage corresponding to the intermediate group corresponds to the tonal voltage table created at the intermediate voltage level. Accordingly, when the input image data RGB is low in brightness, the low voltage reference voltage DDVDH is supplied to the gamma reference voltage generator 260 in the power supply voltage unit 250, .

The gate driver 230 generates a gate signal GS corresponding to a display order of an image based on a gate control signal GCS supplied from the timing controller 220 and supplies the gate signal GS to the gate line GL. The gate driver 230 may be formed in the form of a plurality of integrated circuits or may be formed directly on the substrate of the display panel 100 together with the transistor forming process of each sub pixel SP, ) May be connected to one or both sides of each.

The data driver 240 receives the pixel data DATA and the data control signal DCS from the timing controller 220 and receives a reference gamma voltage Vg selected from a plurality of reference gamma voltage tables from the reference gamma voltage unit 260, The table is supplied. The data driver 240 converts the pixel data DATA into an analog data voltage Vdata using the reference gamma voltage table selected according to the data control signal DCS and outputs the converted data voltage Vdata To the data line DL of the sub-pixel SP. The data driver 240 may be formed in a plurality of integrated circuits (IC), and may be connected to one side and / or both sides of the data line DL.

As described above, in the present invention, the image data input from the power control unit 270 is analyzed to generate a plurality of reference voltages DDVDH_1, DDVDH2, ..., DDVDH_n having different levels according to the gradation of the image data, Power consumption can be reduced by applying a low-level reference voltage to a low-gradation image and by applying a high-level reference voltage to a high-gradation image, which will be described in more detail.

Display devices such as organic electroluminescence display devices are often employed in portable electronic devices. On the other hand, it is a display device that consumes the largest amount of power among many components provided in a portable electronic device. Therefore, in order for the user to use the portable electronic device for a long time, the power consumption of the display device must be minimized.

Conventionally, when displaying an image with low grayscale and an image with high grayscale, reference voltages of the same level are all generated and applied. On the other hand, in the present invention, a reference voltage of a low level is supplied when an image of a low gradation is displayed, and a reference voltage of a high level is supplied when an image of a high gradation is displayed.

For example, conventionally, when implementing a low gradation image, a data voltage (Vdata) of 1-5 V is supplied to the data line (DL), and a data voltage (Vdata) of 6-10 V is applied to the data line (DL). Therefore, power consumption can be reduced when a low-grayscale image is realized as compared with a high-grayscale image. However, conventionally, when a high-grayscale image and a low grayscale image are implemented, the reference voltage of the same level is used, so there is a limit in reducing power consumption in realizing a low grayscale image.

On the other hand, according to the present invention, a low reference voltage is used in comparison with a high-gradation image when implementing a low-gradation image, so that power consumption by a reference voltage at a low gradation can be reduced.

Hereinafter, the structure of the panel driver 200 of the display device according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram showing the structure of a power control unit 270 according to the present invention.

2, the power control unit 270 of the display apparatus according to the present invention includes an input unit 272 for inputting image data RGB from an external system, And a control signal generator 276 for generating and outputting a control signal in accordance with the comparison result of the comparator 274. [

The comparator 274 compares the gray value of the input image data RGB with the set value. At this time, the comparator 274 receives and stores a plurality of set values, and compares the gradation of the image data RGB with the set value to determine the gradation level of the input image data RGB. For example, if one set value is stored in the comparator 274, the image is judged to be two gradations of a high gradation and a low gradation. That is, the comparator 274 compares the input image data (RGB) stored with the two gradation reference levels of the high gradation and the low gradation with the set value, and if it is larger than the set value, And if it is low, it is judged that the image corresponds to the low gradation reference level.

If the two setting values are stored in the comparator 274, the image is judged as the three gradation reference levels of the high gradation, the intermediate gradation and the low gradation. That is, the comparator 274 compares the input image data RGB with the first set value, and if the input image data RGB is larger than the first set value, the comparator 274 determines the image as an image corresponding to the high gradation reference level, If it is lower than the second set value, it is determined that the image corresponds to the relay reference level, and if it is lower than the second set value, it is determined that the image corresponds to the low gradation reference level.

As described above, the comparator 274 analyzes the input image data RGB by storing a plurality of gradation setting values and determines which gradation reference level among the n gradation reference levels corresponds to the inputted image data RGB.

The control signal generator 276 generates a control signal VCNT based on the result input from the comparator 274. [ The control signal VCNT may include information on the gradation reference level classified in the comparator 274, that is, information on the number and size of the gradation reference levels. In addition, the control signal VCNT includes information on which gradation reference level the gradation level of the currently input image data (RGB) corresponds to.

The control signal generator 276 supplies the generated control signal to the power supply voltage unit 250.

Although the voltage controller 270 is configured separately from the timing controller 220 in the drawing, the voltage controller 270 may be included in the timing controller 220. [

3 is a block diagram showing the structure of the power supply voltage unit 250 of the display device according to the present invention.

3, the power supply voltage unit 250 analyzes a plurality of gradation levels according to a control signal VCNT input from the voltage controller 270, and determines a level of a reference voltage to be generated And a reference voltage generator 252 for generating first-n reference voltages DDVDH_1, DDVDH2, ..., DDVDH_n having different voltage levels according to the determination of the level determiner 251 do.

The level determination unit 251 analyzes the number and size of the gradation reference levels based on the control signal VCNT input from the voltage control unit 270 and determines the level of the reference voltage corresponding to each gradation reference level And supplies the analyzed information to the reference voltage generator 252.

The reference voltage generator 252 generates a plurality of reference voltages DDVDH_1, DDVDH2,..., DDVDH_n having different levels based on the information supplied from the level determiner 251. [ The reference voltage generator 252 may generate a plurality of reference voltages having various levels according to information on a gray level reference level input from the power controller 270. For example, when the gradation reference level is two, the reference voltage generator 252 generates a first reference voltage DDVDH_1 of 0-5V level and a second reference voltage DDVDH_2 of 6-10V level, The first reference voltage DDVDH_1 at the 0-3V level, the second reference voltage DDVDH_2 at the 4-6V level, the reference voltage at the 7-10V level The third reference voltage DDVDH_3 of FIG. The reference voltage generator 252 generates the reference voltages DDVDH_1 and DDVDH_2 ... DDVDH_n on the basis of the gradation reference level information input from the power controller 270. In this case, , DDVDH_2 ... DDVDH_n may have the same level difference from each other.

The number of reference voltages DDVDH_1 and DDVDH_2 to DDVDH_n generated by the reference voltage generator 252 is equal to the number of gradation reference levels stored in the comparator 274 of the voltage controller 270, The reference voltages DDVDH_1, DDVDH_2 ... DDVDH_n of the plurality of gradation levels correspond one to one.

4 is a block diagram showing the structure of the gamma reference voltage section 260 of the display apparatus according to the present invention.

4, the gamma reference voltage generator 260 generates a gamma reference voltage from the plurality of reference voltages DDVDH_1, DDVDH2,..., DDVDH_n input from the power supply voltage unit 250 according to a control signal VCNT, A reference voltage selection unit 262 for selecting a reference voltage DDVDH corresponding to the gradation reference level of the reference gray-scale voltages RGB, a reference voltage selection unit 262 for selecting one of the reference gamma voltage tables T1 and T2 corresponding to the plurality of reference voltages DDVDH_1, DDVDH_2 ... DDVDH_n, Tn) from the memory 262 and outputs the reference gamma voltage tables T1, T2 ... Tn from the memory 262. The memory 264 stores the reference gamma voltage tables T1, T2 ... Tn, A gamma reference voltage selection unit 266 for selecting one of a plurality of reference gamma voltage tables T1, T2, ..., Tn according to a voltage DDVDH, And a gamma reference voltage generator 268 for outputting the gamma voltage table T as a gamma reference voltage to the data driver 240 The.

The reference voltage selector 262 selects one reference voltage DDVDH among the plurality of reference voltages DDVDH_1 and DDVDH_2 to DDVDH_n according to the control signal VCNT input from the voltage controller 270, do. The reference voltage selector 254 selects the reference voltage DDVDH corresponding to the gradation reference level because the control signal VCNT includes the gradation reference level information of the input image data RGB.

At this time, when the gradation reference level is composed of two levels of a high gradation and a low gradation, and the reference voltage is also composed of two, the reference voltage selector 254 may have a simple structure such as a switch. In the case of a plurality of gradation reference levels and a plurality of reference voltages, the reference voltage selector 254 may be composed of a multiplexer and a multi-switch, but the present invention is not limited to this configuration.

A plurality of reference gamma voltage tables (T1, T2, ..., Tn) may be stored in the memory 264. At this time, the plurality of reference gamma voltage tables T1, T2, ..., Tn may be created and stored in the same number as the reference voltages DDVDH_1, DDVDH2, ... DDVDH_n generated by the power supply voltage unit 250, The plurality of reference voltages DDVDH_1, DDVDH2 ... DDVDH_n and the plurality of reference gamma voltage tables T1, T2 ... Tn correspond one to one. The plurality of reference gamma voltage tables T1, T2 ... Tn are created in the same number as the plurality of gradation reference levels of the voltage controller 270. The plurality of reference gamma voltage tables T1, One-to-one correspondence with a plurality of gradation reference levels.

The reference gamma voltages GMA1, GMA2, ..., GMA10 are set in the plurality of reference gamma voltage tables T1, T2, ..., Tn. At this time, since the plurality of reference gamma voltage tables T1, T2, ..., Tn correspond to different reference voltages, different reference gamma voltage tables T1, T2, ..., (GMA1, GMA2 ... GMA10) are set. For example, in the first reference gamma voltage table T1, the lowest reference gamma voltages GMA1, GMA2 ... GMA10 are set and the nth reference gamma voltage table Tn is set to the highest reference gamma voltages GMA1, GMA2 ... GMA10) are set. In the reference gamma voltage table between the first reference gamma voltage table T1 and the nth reference gamma voltage table Tn, reference gamma voltages GMA1, GMA2, GMA3, and GMA3 at the levels between the lowest reference gamma voltage and the highest reference gamma voltage are stored. ... GMA10) are set.

The gamma reference voltage selector 266 selects one of the plurality of reference gamma voltage tables T1, T2, ... supplied to the memory 264 according to the selected reference voltage DDVDH input from the reference voltage selector 262. [ Tn) from the reference gamma voltage table. That is, the gamma reference voltage selector 266 selects one reference gamma voltage table T among the plurality of reference gamma voltage tables T1, T2 ... Tn according to the currently input image data RGB. For example, if the currently input image data RGB is the first gradation G1 with the lowest gradation, the first reference gradation voltage table T1 is selected, and if the currently input image data RGB has the highest gradation And selects the nth reference gamma voltage table (Tn) if it is the nth gradation (Gn).

In other words, according to the present invention, one reference gamma voltage table (T) among the plurality of reference gamma voltage tables (T1, T2 ... Tn) is selected according to the gradation of input image data (RGB) A reference gamma voltage table in which a low voltage level is set is selected for the image data (RGB), and a reference gamma voltage table in which the voltage level increases as the gradation is increased is selected.

The gamma reference voltage selector 266 may include a plurality of multiplexers MUX1, MUX2, ..., MUXn, but may have various configurations such as a multi-switch.

The gamma reference voltage generator 268 outputs the specific reference gamma voltage table T selected by the gamma reference voltage selector 260 to the data driver 240 as a gamma reference voltage.

The data driver 240 receives the pixel data DATA and the data control signal DCS from the timing controller 220 and receives the reference gamma voltage table T selected from the reference gamma voltage unit 260 . The data driver 240 converts the pixel data DATA into an analog data voltage Vdata using the reference gamma voltage table T selected in accordance with the data control signal DCS and outputs the converted data voltage Vdata ) To the data line DL of the corresponding sub-pixel SP, thereby realizing an image.

As described above, according to the present invention, power consumption can be reduced when implementing a low-grayscale image as compared with a high-grayscale image, and when implementing a low grayscale image as compared to implementing a high grayscale image, It is possible to reduce the power consumption by the reference voltage at a lower gradation than in the prior art.

Hereinafter, a display device driving method according to the present invention will be described in detail with reference to FIG.

5 is a flow chart showing a method of driving a display device according to the present invention.

5, when the image data RGB is input from the external system in step S101, the voltage controller 270 analyzes the input image data RGB to adjust the gradation of the image data RGB And determines which level of the plurality of gradation reference levels corresponds to the gradation of the image data RGB (S102).

Next, a plurality of gradation reference levels set in the voltage controller 270 are analyzed to generate a plurality of reference voltages DDVDH_1, DDVDH2,..., DDVDH_n corresponding one-to-one with the plurality of gradation reference levels (S103). At this time, the plurality of reference voltages DDVDH_1, DDVDH2, ... DDVDH_n have the same level difference. For example, when n reference voltages DDVDH_1, DDVDH2, ... DDVDH_n are generated and the maximum reference voltage is 10 V, the level difference between the reference voltages DDVDH_1, DDVDH2, ... DDVDH_n is 10 / ).

Thereafter, a reference voltage DDVDH corresponding to the gradation reference level corresponding to the image data RGB among the plurality of reference voltages DDVDH_1, DDVDH2, ..., DDVDH_n is selected and output (S104) Selects one of the plurality of reference gamma voltage tables (T1, T2 ... Tn) stored in the memory 264 based on the reference gamma voltage table (T) (Step S105).

The plurality of reference gamma voltage tables T1, T2, ..., Tn correspond to a plurality of reference voltages DDVDH_1, DDVDH2, ... DDVDH_n. That is, since one reference gamma voltage table T is created for one reference voltage DDVDH, when the reference voltage DDVDH is supplied by the image data RGB, the reference gamma voltage table T corresponding thereto is And a data voltage Vdata according to the reference gamma voltages GMA1, GMA2, ..., GMA10 set in the reference gamma voltage table T is applied to the data lines.

Table 1 and Table 2 are tables illustrating a reference gamma voltage table of a display device according to the present invention. At this time, when the image data RGB is divided into two gradation reference levels and two reference voltages DDVDH_1 and DDVDH_2 are supplied from the power supply voltage unit 250 and two reference gamma voltage tables T1 and T2 are formed Is a reference gamma voltage table.

T1 Voltage (V) DDVDH_1 10 GMA1 9 GMA2 8 GMA3 7 GMA4 6 GMA5 5 GMA6 4 GMA7 3 GMA8 2 GMA9 One GMA10 0

T2 Voltage (V) DDVDH_2 5 GMA1 4 GMA2 4 GMA3 4 GMA4 4 GMA5 4 GMA6 4 GMA7 3 GMA8 2 GMA9 One GMA10 0

The reference voltage DDVDH_1 is 10 V and the reference gamma voltages GMA1, GMA2 ... GMA10 are in the range of 0-10 V when the input image data RGB is a high gray level image, as shown in Table 1 . On the other hand, as shown in Table 2, when the image data RGB is a low gradation image, the reference voltage DDVDH_1 is 5V and the reference gamma voltages GMA1, GMA2 ... GMA10 are in the range of 0-5V I have.

In the case where the gradation reference level is composed of n, n reference gamma voltage tables are also generated, and a plurality of reference gamma voltage tables have a reference voltage (DDVDH) difference of 10 / n (V) The reference gamma voltages GMA1, GMA2 ... GMA10 in the reference gamma voltage table are also changed.

As can be seen from Tables 1 and 2, the reference voltage (DDVDH_1) supplied to the high gradation image is also outputted as a high voltage, and the reference gamma voltages (GMA1, GMA2 ... GMA10) are also outputted as high voltages. On the other hand, in the case of a low-grayscale image, a low voltage is also output for the reference voltage DDVDH_1 supplied, and a low voltage is also outputted for the reference gamma voltages GMA1, GMA2 ... GMA10

In the case of a general display device, the reference voltage (DDVDH) of a fixed level (that is, a high voltage) is always supplied regardless of the gradation level of an image. In contrast, in the present invention, Therefore, the power consumption of the display device can be reduced.

When the selected reference gamma voltage table T is provided to the data driver 240, the data driver 240 generates a reference gamma voltage table T selected according to the data control signal DCS input from the timing controller 220, And supplies the converted data voltage Vdata to the data line DL of the corresponding sub-pixel SP to implement an image.

While a great many are described in the foregoing description, it should be construed as an example of preferred embodiments rather than limiting the scope of the invention. Therefore, the invention should not be construed as limited to the embodiments described, but should be determined by equivalents to the appended claims and the claims.

100: display panel 200:
220: timing controller 230: gate driver
240: Data driver 250: Power supply voltage part
260: gamma reference voltage section 270: voltage control section

Claims (11)

A display panel displaying an image, the display panel including a gate line and a data line; And
And a panel driver for applying a signal to the display panel to drive the display panel and supplying a reference voltage (DDVDH) of a level determined according to a gray level of an image displayed on the display panel. The plasma display apparatus according to claim 1,
A gate driver for applying a gate signal to the gate line;
A data driver for applying a data voltage to the data line;
A timing controller for driving the gate driver and the data driver;
A voltage controller for analyzing the gradation of the image and outputting a control signal according to the analyzed gradation;
A power supply voltage unit for generating a voltage to drive the gate driver, the data driver, and the timing controller to generate a plurality of reference voltages; And
Selects one reference voltage among a plurality of reference voltages input from the power supply voltage unit according to the control signal, selects one reference gamma voltage table (T) among a plurality of reference gamma voltage tables according to the selected reference voltage, And a gamma reference voltage section provided to the driving section. 3. The apparatus according to claim 2,
A comparison unit which generates a plurality of gradation reference levels having different levels and compares the gradation of the image data input from the external system with a set value; And
And a control signal generator for generating and outputting a control signal according to the comparison result of the comparator. The power supply unit according to claim 3,
A level determination unit for analyzing and determining a plurality of gradation reference levels according to a control signal of the voltage control unit; And
And a reference voltage generation unit for generating a plurality of reference voltages having different voltage levels according to the analysis of the level determination unit. The display device according to claim 4, wherein the plurality of gradation reference levels correspond one-to-one with a plurality of reference voltages. The apparatus of claim 4, wherein the gamma reference voltage unit comprises:
A reference voltage selection unit for selecting a reference voltage corresponding to a gradation reference level of the image from a plurality of reference voltages input from the power supply voltage unit according to a control signal;
A memory for storing a plurality of reference gamma voltage tables corresponding to the plurality of reference voltages;
A gamma reference voltage selector for receiving the plurality of reference gamma voltage tables from the memory and selecting one of a plurality of reference gamma voltage tables according to a selected reference voltage output from the reference voltage selector; And
And a gamma reference voltage generator for outputting the reference gamma voltage table selected by the gamma reference voltage selector to a data driver as a gamma reference voltage. The display device according to claim 6, wherein the plurality of reference gamma voltage tables correspond one-to-one with a plurality of reference voltages. The display device according to claim 6, wherein a plurality of reference gamma voltages are set in each reference gamma voltage table. The display device according to claim 6, wherein the reference gamma voltage table in which a low voltage level is set is selected when the gradation of the input image is low, and the reference gamma voltage table in which the voltage level increases as the gradation is increased. The display device of claim 6, wherein the gamma reference voltage selector includes a plurality of multiplexers. Analyzing image data from an external system to determine which level of the plurality of gradation reference levels corresponds to the gradation of the image data;
Analyzing the plurality of gradation reference levels to generate a plurality of reference voltages corresponding to the plurality of gradation reference levels;
Selecting a reference voltage corresponding to a gradation reference level of image data among a plurality of reference voltages;
Selecting one reference gamma voltage table from among a plurality of reference gamma voltage tables based on the selected reference voltage; And
And converting the pixel data into a data voltage using the selected reference gamma voltage table and supplying the data voltage to the data line.

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