KR100844776B1 - Organic light emitting display device and dirving method thereof - Google Patents

Abstract

An OLED(Organic Light Emitting Display) device and a driving method thereof are provided to enhance visibility by generating variation data corresponding to optic detection signals. A pixel unit(100) includes scan lines, light emitting control lines, data lines, and plural pixels. A scan driver(200) applies scan and light emitting control signals to the scan lines. A data driver(300) applies data signals to the data lines. An optic sensor(700) generates an optic detection signal corresponding to the intensity of external lights. A first controller(400) selects a gamma value corresponding to the lightness of the external lights, generates a gamma compensation signal corresponding to the selected gamma value, and adjusts a gray scale voltage of the data signals. A second controller(500) generates a selection signal by comparing the optic detection signal with a reference value and provides data, which is varied corresponding to the selection signal, to the data driver. A third controller(600) supplies a luminance control signal for adjusting the pulse width of light emitting control signals to the scan driver. The first and second controllers are selectively driven based on the lightness of ambient lights.

Description

Organic electroluminescent display and driving method thereof

1 is a block diagram illustrating an organic electroluminescent display device according to an exemplary embodiment of the present invention.

FIG. 2 is a block diagram illustrating an embodiment of the configuration of the first controller illustrated in FIG. 1.

3 is a diagram illustrating an example of the A / D converter illustrated in FIG. 2.

4 is a diagram illustrating an example of the gamma correction circuit illustrated in FIG. 2.

5A to 5B are diagrams illustrating gamma curves according to the gamma correction circuit of FIG. 4.

6 is a block diagram illustrating an example of a configuration of a second control unit shown in FIG. 1.

7A to 7D are diagrams illustrating an example of calculating target saturation data for each subpixel using the saturation change matrix shown in FIG. 6.

FIG. 8 is a diagram illustrating an example of the configuration of the third control unit illustrated in FIG. 1.

FIG. 9 is a table illustrating an embodiment of a lookup table illustrated in FIG. 8.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent display, and more particularly, to a control unit for reducing power consumption and / or improving outdoor visibility and an organic electroluminescent display including the same.

Recently, various flat panel displays have been developed to reduce weight and volume, which are disadvantages of cathode ray tubes. The flat panel display includes a liquid crystal display, a field emission display, a plasma display panel, and an organic light emitting display.

Among the flat panel displays, an organic light emitting display device displays an image using organic light emitting diodes (OLEDs) that generate light by recombination of electrons and holes.

Such an organic electroluminescent display device has been greatly expanded in the application fields such as PDA, MP3, DSC, etc. in addition to mobile phones due to various advantages such as excellent color reproducibility and thin thickness.

However, since the organic light emitting display emits light according to a change in the amount of current, a high current consumption is required when emitting bright light, and thus, low power is required for various display applications.

However, if the driving voltage of the image is simply lowered collectively to reduce the power consumption of the organic electroluminescent display having different emission levels according to the change in the amount of current, the brightness of the unwanted portion of the image is reduced and thus the image quality is deteriorated. There is this.

In addition, the portable display device, which is a representative application example of the organic light emitting display device, has characteristics of being exposed to various environments, and thus the visibility of the image displayed on the portable display device may vary depending on the surrounding environment such as ambient illumination. have. In particular, the visibility of the image displayed on the portable display device may be sharply degraded under sunlight having a much higher ambient illumination than the brightness of the image.

Accordingly, there is a demand for the development of an organic light emitting display device capable of improving visibility in response to a surrounding environment.

It is an object of the present invention to provide an organic electroluminescent display and a driving method thereof for reducing power consumption and / or improving outdoor visibility in response to a user's request.

In order to achieve the above object, a first aspect of the present invention provides a plurality of scanning lines for transmitting a scanning signal and a plurality of light emitting control lines for providing a light emission control signal, a plurality of data lines for transmitting a data signal, and the scanning lines and light emission control. A pixel portion including a plurality of pixels respectively connected to a line and a data line; A scan driver for sequentially generating the scan signal and the emission control signal and applying the scan signal to the plurality of scan lines; A data driver for generating the data signal and applying the data signal to the data line; An optical sensor for generating a light detection signal corresponding to the intensity of external light; A first control unit which selects a gamma value corresponding to the brightness of the ambient light detected by the optical sensor, and outputs a gamma correction signal corresponding to the selected gamma value to adjust the gray voltage of the data signal; Generating a selection signal by comparing the photo-sensing signal with a preset reference value, and providing data (R'G'B 'Data) of changing input image data (RGB Data) to the data driver in response to the selection signal; A second control unit; And a third controller configured to provide a brightness control signal for adjusting the pulse width of the light emission control signal to the scan driver, and when the illumination is equal to or less than a predetermined reference value according to the brightness level of the ambient light detected by the optical sensor. According to an aspect of the present invention, there is provided an organic electroluminescent display device in which the first control unit operates and the second control unit operates when the illuminance exceeds the reference value.

In order to achieve the above object, a second aspect of the present invention provides a method of driving an organic light emitting display device that displays an image in response to a data signal, a scan signal, and a light emission control signal. If the ambient light is greater than or equal to the reference value, the chroma signal of the input image data is changed to convert the data signal, and if the ambient light is less than or equal to the reference value, the gamma value is adjusted in response to the ambient light. First step; Generating the data signal in response to the converted video signal; And a third step of adjusting the pulse width of the emission control signal by grasping the sum of the image data.

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

1 is a block diagram illustrating an organic electroluminescent display device according to an exemplary embodiment of the present invention.

Referring to FIG. 1, an organic light emitting display device according to an exemplary embodiment of the present invention includes a pixel unit 100, a scan driver 200, a data driver 300, and first to third controllers 400, 500, and 600. And an optical sensor 700.

The pixel unit 100 includes a plurality of pixels 110 connected to scan lines S1 to Sn, emission control lines EM1 to EMn, and data lines D1 to Dm. Here, one pixel 110 may include at least two subpixels each having an organic light emitting diode and emitting light of different colors.

The pixel unit 100 is supplied from the first power source ELVdd and the second power source ELVss, the scan signal and the emission control signal supplied from the scan driver 200, and the data driver 300. An image is displayed in response to the data signal.

The scan driver 200 generates a scan signal and a light emission control signal. The scan signals generated by the scan driver 200 are sequentially supplied to the respective scan lines S1 to Sn, and the emission control signals are sequentially supplied to the respective emission control lines EM1 to EMn.

In this case, the emission control signal is controlled by the luminance control signal provided from the third control unit 600, and the overall brightness of the pixel unit 100 according to the change in the pulse width of the controlled emission control signal. Is adjusted.

The data driver 300 receives image data converted by at least one of the first and second controllers 400 and 500 and generates a data signal corresponding thereto. The data signal generated by the data driver 300 is supplied to the data lines D1 to Dm to be synchronized with the scan signal and transferred to each pixel 110.

The first controller 400 generates a detection signal corresponding to the brightness of the ambient light sensed by the optical sensor 700, selects a gamma value according to the detected signal, and outputs a gamma correction signal corresponding to the selected gamma value. The brightness of the pixel unit 100 is controlled by adjusting the gray voltage of the data signal.

In addition, the second controller 500 generates a selection signal for selecting any one of at least three modes by comparing the light detection signal Ssens input from the optical sensor 700 with a preset reference value. The data converter 400 stores the input image data RGB data or the change data R'G'B 'data in which the input image data RGB data is changed in response to the selection signal.

At this time, the first control unit 400 operates in the case of illuminance below a predetermined reference value according to the brightness level of the ambient light sensed by the optical sensor 700, and in the case of the illuminance above the reference value, the second control unit 500 It is characterized by the operation.

More specifically, the second control unit 500 determines the change of the input image data RGB data according to the light detection signal input from the optical sensor 700, and determines the luminance and / or the input image data RGB data. Generate and change the change data (R'G'B 'Data) with the saturation value. At this time, the change data (R'G'B 'Data) is generated by applying at least two modes in response to the selection signal, and the change data (R'G'B' Data) stored in the second control unit (500). Alternatively, the input image data RGB data is input to the data driver 300.

That is, the second control unit 500 saturates the input image data RGB data to improve visibility when the light detection signal Ssens corresponding to the case where the ambient light is equal to or greater than a reference value, such as strong sunlight, is supplied. Change data (R'G'B 'Data) having an increased value is generated. In addition, when generating the change data (R'G'B 'Data), by selecting any one of at least two modes of controlling to change the input image data (RGB Data) in response to the light detection signal (Ssens) By generating change data (R'G'B 'Data), it is possible to correspond to the intensity of external light in more various ways.

In addition, the optical sensor 700 includes a photosensitive device such as a transistor or a photodiode to sense the intensity of external light and generates a photosensitive signal Ssens corresponding thereto. The light detection signal Ssens generated by the light sensor 700 is supplied to the first control unit 400 and / or the second control unit 500.

In addition, the third controller 600 serves to provide the scan driver 200 with a luminance control signal for adjusting the pulse width of the light emission control signal provided from the scan driver 200, and thereby the pixel unit 100. The amount of current flowing through the control panel is adjusted, and the overall brightness of the pixel unit 100 is adjusted by preventing current above a predetermined value from flowing in the pixel unit 100.

The organic light emitting display device having the above configuration can reduce power consumption and / or improve outdoor visibility in response to a user's request by the operations of the first to third control units 400, 500, and 600, respectively. .

Specific configurations and operations of the first to third controllers 400, 500, and 600 will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram illustrating an embodiment of the configuration of the first controller illustrated in FIG. 1.

2, the first controller 400 includes an A / D converter 412, a counter 413, a conversion processor 414, a register generator 415, a first selector 416, and a second selector. 417 and a gamma correction circuit 418.

The A / D converter 412 compares the analog sense signal output from the optical sensor 700 with a set reference voltage and outputs a digital sense signal corresponding thereto. For example, a sensing signal of '11' is output at a stage where brightness of the surroundings is the brightest, and a sensing signal of '10' is output at a stage where the surrounding brightness is somewhat bright. In addition, the sensing signal of '01' is output at a stage where the surrounding brightness is a little dark, and the sensing signal of '00' is output at a stage where the surrounding brightness is the darkest.

The counter 413 counts a predetermined number for a predetermined time by the vertical synchronization signal Vsync supplied from the outside and outputs a counting signal Cs corresponding thereto. For example, in the case of the counter 213 referring to a binary value of 2 bits, the counter 320 is initialized to '00' when the vertical synchronization signal Vsync is input, and then shifts the clock CLK signal in sequence. Count up to '11'. When the vertical sync signal Vsync is input to the counter 320 again, the counter 320 is reset to an initialization state. In this manner, the counter 320 sequentially counts the numbers '00' to '11' during one frame period. The counting signal Cs corresponding to the counted number is output to the conversion processor 414.

The conversion processor 414 outputs a control signal for selecting a set value of each register by using the counting signal Cs output from the counter 413 and the detection signal output from the A / D converter 412. That is, when the counter 413 outputs a predetermined signal, the counter 413 outputs a control signal corresponding to the selected sensing signal, and maintains the control signal output by the counter during the period of one frame. When the next frame is reached, the control signal is reset and the control signal corresponding to the detection signal output from the A / D converter 412 is output again and maintained for one frame period. For example, if the ambient light is the brightest, the conversion processor 414 outputs a control signal corresponding to the detection signal of '11', maintains the control signal for one frame period counted by the counter 413, and maintains the ambient light. In this darkest state, the control signal corresponding to the detection signal of '00' is output and the control signal is maintained for one frame period counted by the counter 413. In addition, even when the ambient light is somewhat bright or the ambient light is somewhat dark, the control signals corresponding to the sensing signals of '10' and '01' are output and maintained, respectively, as in the above-described operation.

The register generator 415 divides the brightness of the ambient light into a plurality of stages and stores a plurality of register setting values corresponding to each stage.

The first selector 416 selects a register set value corresponding to the control signal set by the conversion processor 414 from among a plurality of register set values stored in the register generator 415.

The second selector 417 receives a setting value of 1 bit that controls on / off from the outside. When '1' is selected, the first controller 400 operates, and '0' is selected. When selected, the first control unit is turned off to selectively control brightness according to ambient light.

The gamma correction circuit 418 generates a plurality of gamma correction signals corresponding to the register setting values selected according to the control signal set by the conversion processing unit 414. At this time, the control signal corresponds to the detection signal output from the optical sensor 700, so that the gamma correction signal has a different value according to the brightness of the ambient light. The above operation occurs for each of R, G, and B.

3 is a diagram illustrating an example of the A / D converter illustrated in FIG. 2. Referring to FIG. 3, the A / D converter 412 includes first to third selectors 21, 22, 23, first to third comparators 24, 25, 26, and an adder 27. do.

The first to third selectors 21, 22, and 23 receive a plurality of gray voltages distributed through a plurality of resistor rows that generate a plurality of gray voltages VHI to VLO, and respectively, to different setting values of 2 bits. The corresponding gray scale voltage is output and determined as the reference voltages VH to VL.

The first comparator 24 compares the analog sensing signal SA with the first reference voltage VH and outputs the result. For example, '1' is output when the analog sense signal SA is greater than the first reference voltage VH, and '0' when the analog sense signal SA is less than the first reference voltage VH. Outputs

In the same way, the second comparator 25 outputs the result of comparing the analog sense signal SA and the second reference voltage VM, and the third comparator 26 outputs the analog sense signal SA and the third reference. The result of comparing the voltage VL is output. In addition, by varying the first to third reference voltages VH to VL, an area of the analog sensing signal SA corresponding to the same digital sensing signal SD may be changed.

The adder 27 adds all the result values output from the first to third comparators 24 to 26 and outputs them as a 2-bit digital sensing signal SD.

Assume that the first reference voltage (VH) is 1V, the second reference voltage (VM) is 2V, and the third reference voltage (VL) is 3V, and the voltage value of the analog sensing signal SA is assumed to be larger as the ambient light becomes brighter. Referring to the A / D converter represented in Figure 3 as follows. When the analog sense signal SA is smaller than 1V, the first to third comparators 24 to 26 output '0', '0' and '0', respectively, so that the adder 27 has a digital value of '00'. Output the detection signal SD. When the analog sense signal SA is between 1V and 2V, the first to third comparators 24 to 26 output '1', '0', and '0', respectively, so that the adder 27 is '01'. Outputs a digital detection signal (SD). In the same manner, when the analog sense signal SA is between 2V and 3V, the adder 27 outputs a digital sense signal SD of '10', and when the analog sense signal SA is 3V or more, the adder ( 27) outputs a digital sensing signal SD of '11'. The A / D converter 212 operates in this manner, dividing the surrounding brightness into four stages, outputting '00' at the darkest stage, '01' at the somewhat darker stage, and ' 10 'and' 11 'in the brightest stage.

4 is a diagram illustrating an example of the gamma correction circuit illustrated in FIG. 2. Referring to FIG. 4, the gamma correction circuit includes a ladder resistor 61, an amplitude adjustment register 62, a curve adjustment register 63, a first selector 64 to a sixth selector 69, and a gray voltage amplifier ( 70).

The ladder resistor 61 is configured as a reference voltage by setting the highest level voltage VHI supplied from the outside, and a plurality of variable resistors included between the lowest level voltage VLO and the reference voltage are connected in series. A plurality of gray voltages are generated through 61. In addition, when the ladder resistance 61 value is reduced, the amplitude adjustment range is narrowed, but the adjustment accuracy is improved. On the other hand, when the value of the ladder resistor 61 is increased, the amplitude adjustment range is wider, but the adjustment accuracy is lowered.

The amplitude adjustment register 62 outputs a 3-bit register setting value to the first selector 64 and a 7-bit register setting value to the second selector 65. At this time, the number of selectable gray scales can be increased by increasing the number of setting bits, and the gray scale voltage can be selected differently by changing the register setting value.

The curve adjustment register 63 outputs a 4-bit register setting value to each of the third selector 66 to the sixth selector 69. In this case, the register setting value may be changed, and the gray level voltage selectable according to the register setting value may be adjusted.

The upper 10 bits of the register values generated by the register generator 215 are input to the amplitude adjustment register 62, and the lower 16 bits are input to the curve adjustment register 63, respectively, and are selected as register setting values.

The first selector 64 selects a gray voltage corresponding to a 3-bit register setting value set in the amplitude adjusting register 62 among the plurality of gray voltages distributed through the ladder resistor 61 and outputs the gray voltage corresponding to the highest gray voltage. .

The second selector 65 selects a gray voltage corresponding to a 7-bit register setting value set in the amplitude adjusting register 62 among the plurality of gray voltages distributed through the ladder resistor 61 and outputs the gray voltage corresponding to the lowest gray voltage.

The third selector 66 divides the voltage between the gray voltage output from the first selector 64 and the gray voltage output from the second selector 65 into a plurality of gray voltages through a plurality of resistor columns, and The gradation voltage corresponding to the register setting value is selected and output.

The fourth selector 67 divides the voltage between the gray voltage output from the first selector 64 and the gray voltage output from the third selector 66 through a plurality of resistor columns and corresponds to a 4-bit register setting value. Select the gradation voltage to be output.

The fifth selector 35 selects and outputs a gray voltage corresponding to a 4-bit register setting value among the gray voltages between the first selector 31 and the fourth selector 34.

The sixth selector 36 selects and outputs a gray scale voltage corresponding to a 4-bit register setting value among the plurality of gray voltages between the first selector 31 and the fifth selector 35. By the above operation, the curve adjustment of the middle gray scale portion can be made in accordance with the register setting value of the curve adjustment register 63, so that the gamma characteristic can be easily adjusted according to the characteristics of each light emitting element. Also, to make the gamma curve characteristic convex downward, the potential difference between each gray scale becomes larger as the small gray scale is displayed. On the other hand, to make the gamma curve characteristic convex upward, the potential difference between each gray scale becomes smaller as the small gray scale is displayed. What is necessary is just to set the resistance value of each ladder resistor 61.

The gray voltage amplifier 37 outputs a plurality of gray voltages corresponding to each of the plurality of gray levels to be displayed on the pixel unit 100. 4 shows the output of the gray scale voltage corresponding to 64 gray scales.

In the above-described operation, the curve is adjusted by installing a gamma correction circuit for each of the R, G, and B groups so that R, G, and B obtain almost the same luminance characteristics in consideration of variations in the light emitting device's own characteristics. The amplitude and the curve through the register 63 and the amplitude adjustment register 62 may be set differently for each of R, G, and B.

5A to 5B are diagrams illustrating gamma curves according to the gamma correction circuit of FIG. 4.

5A shows that the amplitude of the lower level gray voltage can be adjusted by changing the lower level gray voltage according to the 7-bit register setting value set in the amplitude adjusting register 62 without changing the upper level gray voltage. A1 is a gamma curve corresponding to a detection signal in a state where the ambient brightness is the darkest, and A2 is a gamma curve corresponding to a detection signal in a state where the ambient brightness is somewhat dark.

In addition, reference numeral A3 denotes a gamma curve corresponding to a detection signal in a state where the surrounding brightness is somewhat bright, and reference numeral A4 denotes a gamma curve corresponding to a detection signal in a state where the ambient brightness is the brightest. In this case, when the amplitude voltage of the gray scale voltage is to be adjusted small, the second selector may be set to select the highest level voltage by adjusting the register setting value of the amplitude adjusting register 62. Also, when the amplitude voltage of the gradation voltage is to be largely adjusted, the second selector is set to select the lowest level voltage.

FIG. 5B shows that the gamma curve is adjusted by changing only the gray level voltage of the middle level without changing the high level gray level voltage and the low level gray level voltage according to the register setting value set in the curve adjusting register 63. A 4-bit register setting value is input to each of the third selector 33 to the sixth selector 36, and four gamma values corresponding to the register setting value are selected to generate a gamma curve. The off voltage Voff is a voltage corresponding to black gradation (gradation value 0), and the on voltage Von is a voltage corresponding to white gradation (gradation value 63). The degree of change of the slope of the curve C2 is larger than the change of the slope of the curve corresponding to C1 and smaller than the degree of change of the slope of the C3 curve. By changing the setting value of the gamma adjustment register through FIGS. 5A and 5B, the gray scale voltage is changed to generate a gamma curve, thereby adjusting the brightness of each of the pixels 110 included in the pixel unit 100. Able to know.

6 is a block diagram illustrating an example of a configuration of a second control unit shown in FIG. 1.

Referring to FIG. 6, the second controller 500 includes a comparator 510, a controller 520, a first calculator 530, a chroma change matrix 535, a second calculator 540, and a reference lookup table unit ( 545, and a memory 550.

The comparison unit 510 outputs a selection signal Ssel for selecting any one of at least three modes by comparing the light detection signal Ssens supplied from the optical sensor 700 with a preset reference value.

More specifically, the comparator 510 sets at least three modes based on a preset reference value corresponding to the magnitude of the light sensing signal Ssens, and outputs a selection signal Ssel corresponding thereto. For convenience, hereinafter, it will be assumed that the comparator 510 sets three modes in response to the light detection signal Ssens.

For example, when the light detection signal Ssens belongs to the minimum range among preset reference values, that is, when the intensity of external light is within the weakest range, the comparator 510 does not change the input image data RGB data. Set to the first mode to avoid the output, and output a selection signal Ssel corresponding thereto.

When the light detection signal Ssens belongs to the maximum range among preset reference values, for example, when the intensity of the external light is within the strongest range, such as when the sunlight is directly incident, the comparator 510 may input the input image. The third mode may be set to control the saturation and / or luminance of the RGB data to be changed as much as possible, and the corresponding selection signal Ssel may be output.

In addition, in other cases, that is, when the light detection signal Ssens falls between a minimum range and a maximum range of preset reference values, for example, when sunlight is indirectly incident, the comparator 510 may generate input image data RGB. The second mode is controlled to change the saturation and / or luminance of the data), and a corresponding selection signal Ssel may be output. At this time, in the second mode, the change value is set to be smaller than that in the third mode. The selection signal Ssel output from the comparator 510 is input to the controller 520.

However, in the exemplary embodiment of the present invention, when the illuminance is less than or equal to a preset reference value according to the brightness level of the ambient light sensed by the optical sensor 700, the first controller 400 operates, and when the illuminance is greater than or equal to the reference value, Since the control unit 500 operates, substantially the second control unit 500 preferably operates in the second mode and the third mode.

The controller 520 determines whether to change the input image data RGB data in response to the selection signal Ssel input from the comparator 510.

The controller 520 transmits the input image data RGB data to the first calculator 530 or stores the input image data RGB data in the memory 450 according to whether the determined input image data RGB data is changed.

For example, the controller 420 stores the input image data RGB data when the intensity of external light is the weakest among the selection signals Ssel, that is, when the selection signal Ssel corresponding to the first mode is supplied. 550).

In other cases, that is, when the selection signal Ssel for selecting the second and third modes is supplied, the controller 420 transmits the input image data RGB data to the first calculator 530. , And transmits the selection signal (Ssel) input to the second operation unit 540.

The first calculator 530 generates the pixel chroma data Sout corresponding to the input image data RGB data transmitted from the controller 520 with reference to the chroma change matrix 535.

For example, the first calculator 530 calculates each subpixel input data (Rin, Gin, Bin) and chroma change matrix 535 included in the input image data (RGB Data) to target saturation for each subpixel. The data Rs, Gs, and Bs may be calculated and the pixel saturation data Sout may be generated using the data Rs, Gs, and Bs.

Here, the target saturation data Rs, Gs, and Bs for each subpixel may be calculated using the saturation change matrix 435. A method of calculating target saturation data Rs, Gs, and Bs for each subpixel will be described later with reference to FIGS. 7A to 7D.

The pixel saturation data Sout is calculated from the target saturation data Rs, Gs, and Bs for each subpixel, and is set to the maximum value among the target saturation data values Rs, Gs, and Bs for each subpixel, or For example, the pixel may be set to a predetermined value corresponding to the difference between the maximum value and the minimum value of the target saturation data values Rs, Gs, and Bs for each subpixel.

The pixel saturation data Sout generated in the first calculator 530 is supplied to the second calculator 540.

The second calculator 540 changes the data R ′ from the reference lookup table 545 in response to the pixel chroma data Sout and the selection signal Ssel supplied from the first calculator 530 and the controller 520, respectively. G'B 'Data) is extracted and stored in the memory 550.

More specifically, the second calculator 540 may include one of a first chroma and luminance lookup table LUT and a second chroma and luminance lookup table included in the reference lookup table 545 in response to the selection signal Ssel. Select.

The second calculator 540 extracts change data R'G'B 'data having chroma and luminance values corresponding to the pixel chroma data Sout from the selected lookup table.

Here, the chroma lookup table and the luminance lookup table mean a table referred to to extract the chroma change value and the luminance change value corresponding to the pixel chroma data Sout, respectively.

In this case, the first chroma and luminance lookup tables and the second chroma and luminance lookup tables may store different chroma and / or luminance values corresponding to the same pixel chroma data Sout. For example, the first saturation and luminance lookup table selected by the selection signal Ssel for selecting the second mode may be less than the second saturation and luminance lookup table selected by the selection signal Ssel for selecting the third mode. The saturation and / or luminance values may be set low.

On the other hand, when the pixel saturation data Sout which is not stored in the reference lookup table 545 is input, the second calculator 540 is configured to compare the pixel saturation data Sout among the values stored in the reference lookup table 545. The change data R'G'B 'Data may be extracted by referring to two adjacent values. For example, the second calculator 540 changes the linear interpolation between a maximum value among smaller values than the input pixel chroma data Sout and a change value corresponding to a minimum value among the values larger than the pixel chroma data Sout. Data R'G'B 'Data may be extracted.

The memory 550 stores input image data RGB data transmitted from the controller 520 or change data R'G'B 'data supplied from the second calculator 540. The input image data RGB data or the change data R'G'B 'data stored in the memory 550 is input to the data driver 300.

7A to 7D are diagrams illustrating an example of calculating target saturation data for each subpixel using the saturation change matrix shown in FIG. 6.

Referring to FIGS. 7A to 7D, the first calculator 530 may determine input data (Rin, Gin, and Bin) for each subpixel included in the chroma change matrix 535 (A) and the input image data (RGB Data). By multiplying, the target saturation data Rs, Gs, and Bs for each subpixel may be calculated (FIG. 7A).

Saturation change matrix (535, A) is a matrix to adjust the saturation using the saturation coefficient (k) to determine the saturation control, the input data for each subpixel by the value of the saturation factor (k) The target saturation data Rs, Gs, and Bs for each subpixel are calculated by converting the values of (Rin, Gin, and Bin).

The saturation change matrix 535, A is set in consideration of the white balance of the pixel, and a matrix as shown in Fig. 7B is generally used (Fig. 7B).

That is, the first calculator 530 multiplies the chroma change matrix 535 and A of the sub-pixel sub-input data (Rin, Gin, and Bin) shown in FIG. 7B to target sub-pixel target saturation data (Rs, Gs, and Bs). ) Can be calculated.

Here, if the value of the saturation coefficient k is greater than 1, the saturation increases, and if it is less than 1, the saturation decreases. When the saturation coefficient k has a value of 1, the saturation change matrices 535 and A become a unit matrix of 3x3, so that the saturation is not changed (Fig. 7C).

In addition, when the saturation coefficient k value is 0, as shown in FIG. 7D, all subpixel target saturation data Rs, Gs, and Bs are set to be equal to the ratio of the white balance, and thus gray image without saturation. (Fig. 7d)

FIG. 8 is a diagram illustrating an example of the configuration of the third control unit illustrated in FIG. 1. Referring to FIG. 8, the third control unit 600 controls the brightness according to the emission rate of the pixel unit 100, which is a data summing unit 621, a lookup table 622, and the like. The brightness control driver 623 is included.

The data summing unit 621 determines the size of the frame data, which is the sum of the video data input to each of the pixels 110 emitting light during one frame. That is, the sum of video data input to each of the plurality of pixels 110 emitting light for one frame is called frame data, and is called frame data. When the size of the frame data is large, the emission rate of the pixel unit 100 is high, This means that there are many pixels 110 for displaying a high gradation image.

That is, if the size of the frame data is large, it means that the amount of current flowing through the entire pixel portion 100 is large. If the size of the frame data is greater than or equal to a predetermined value, the luminance of the pixel portion 100 is controlled to control the entire pixel portion 100. Decrease the brightness. In addition, when the brightness of the pixel unit 100 decreases, the pixel 110 that emits light has a high luminance and maintains a large brightness difference from the pixel 110 that does not emit light, that is, a large contrast ratio.

On the other hand, when the brightness of the pixel unit 100 does not decrease, the light emission time of the pixels 110 emitting light is kept long, so that the luminance is increased. Accordingly, the luminance of the pixel 110 and the pixels 110 that do not emit light are increased. The contrast ratio will increase. That is, as the contrast ratio between the pixel 110 that emits light and the pixel 110 that does not emit light increases, the image may be seen more clearly.

The lookup table 622 stores information about the ratio between the light emission period and the non-light emission period of the emission control signal corresponding to the upper 5 bit values of the frame data. The information stored in the lookup table 622 may be used to determine the brightness of the pixel unit 100 that emits light for one frame.

The luminance control driver 623 outputs a luminance control signal when the size of the frame data of the pixel unit 100 is greater than or equal to a predetermined size, and the emission control signal input to the pixel unit 100 in response to the output luminance control signal. Adjust the ratio between the light emitting section and the non-light emitting section. In this case, if the luminance control ratio is continuously increased in proportion to the increase of the luminance of the pixel unit 100, when the luminance of the pixel unit 100 becomes very high, the screen may not be sufficiently bright due to excessive luminance control. It simply results in a drop in overall brightness. Therefore, the maximum control range of the luminance is set to appropriately adjust the brightness of the entire pixel portion 100.

FIG. 9 is a table illustrating an embodiment of a lookup table illustrated in FIG. 8. 9 illustrates a lookup table 622 in which the emission ratio is limited to 50% of the maximum value according to the luminance of the pixel unit 100.

Referring to FIG. 9, when the ratio of the light emitting area of the pixel portion 100 is 36% or less of the entire pixel portion 100, the luminance of the pixel portion 100 is not limited, and When the ratio of the light emitting area is 36% or more of the entire pixel portion 100, the luminance of the pixel portion 100 is limited so that the area in which the pixel portion 100 emits light at the maximum luminance increases. Also increase. In this case, the ratio of the light emitting area is a variable determined by Equation 9 below.

In addition, the maximum limiting ratio is limited to 50% in order to prevent excessive luminance limitation, so that even if most of the pixels 110 emit light at the maximum luminance, the luminance limiting ratio does not become 50% or more.

According to the present invention, by adjusting the brightness according to the ambient light, the brightness according to the amount of light emitted by the pixel portion has the effect of improving the visibility and power consumption, adaptive input signal size that can not recognize the deterioration of image quality By reducing power consumption, power consumption can be maximized by reducing power consumption without significantly affecting image quality.

In addition, the visibility can be improved by changing the input image data in response to the surrounding environment such as the intensity of the external light. In particular, when exposed to external light of a predetermined illuminance, the change data which increases the saturation of the input image data, etc. is generated and By displaying the corresponding video, visibility can be improved even under strong sunlight.

In addition, when generating the change data, one of at least two modes of controlling to change the input image data in response to the light detection signal may be selected to generate the change data, thereby more variously corresponding to the intensity of the external light.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (17)

A plurality of scanning lines for transmitting a scan signal and a plurality of light emitting control lines for providing a light emission control signal, a plurality of data lines for transmitting a data signal, and a plurality of pixels respectively connected to the scanning lines, light emitting control lines, and data lines A pixel portion; A scan driver for sequentially generating the scan signal and the emission control signal and applying the scan signal to the plurality of scan lines; A data driver for generating the data signal and applying the data signal to the data line; An optical sensor for generating a light detection signal corresponding to the intensity of external light; A first control unit which selects a gamma value corresponding to the brightness of the ambient light detected by the optical sensor, and outputs a gamma correction signal corresponding to the selected gamma value to adjust the gray voltage of the data signal; Generating a selection signal by comparing the photo-sensing signal with a preset reference value, and providing data (R'G'B 'Data) of changing input image data (RGB Data) to the data driver in response to the selection signal; A second control unit; And A third controller configured to provide a brightness control signal for adjusting a pulse width of the light emission control signal to the scan driver; The first control unit operates when the illuminance is lower than a predetermined reference value according to the brightness level of the ambient light detected by the optical sensor, and when the illuminance exceeds the reference value, the second control unit operates. delete The method of claim 1, And the data driver receives the image data converted by the second controller, generates a data signal corresponding to the image data, and transmits the generated data signal to a data line. The method of claim 1, The first control unit, An analog-digital converter for converting the analog sense signal output from the optical sensor into a digital sense signal; A counter for counting a predetermined number during a period of one frame and generating a counting signal corresponding thereto; A conversion processor for outputting a control signal corresponding to the digital detection signal and the counting signal;  A register generator for dividing the brightness of the ambient light into a plurality of stages and storing a plurality of register setting values corresponding to each stage; A first selector for selecting and outputting one register set value from among the plurality of register set values in response to a control signal set by the conversion processor from among a plurality of register set values stored in the register generator; And And a gamma correction circuit configured to generate a gamma correction signal according to the control signal of the conversion processor. The method of claim 4, wherein And the first controller further comprises a second selector to control on and off of the first controller. The method of claim 1, The second control unit, A comparator for comparing a sensing signal by the optical sensor with a preset reference value and outputting a selection signal for selecting any one of at least three modes; A controller configured to determine whether to change the input image data in response to the selection signal; A first calculator configured to generate pixel chroma data corresponding to the input image data transmitted from the controller; A second calculator configured to extract change data corresponding to the pixel chroma data and the selection signal; And And a memory configured to store the input image data transmitted from the controller or the change data supplied from the second calculator. The method of claim 6, And a chroma change matrix referred to by the first calculator. The method of claim 7, wherein And the first calculator calculates target saturation data for each subpixel by calculating subpixel input data and the chroma change matrix included in the input image data, and generates the pixel saturation data using the same. Electroluminescent display. The method of claim 7, wherein And a reference lookup table, which is referred to by the second calculator and includes a first saturation and luminance lookup table and a second saturation and luminance lookup table. The method of claim 9, The second calculator selects one of the first chroma and luminance lookup tables and the second chroma and luminance lookup tables in response to the pixel chroma data and the selection signal, and extracts the change data from the selected lookup table. An organic electroluminescent display. The method of claim 1, The third control unit, A data summing unit for generating frame data by summing video data input for one frame period; A lookup table that stores information on brightness control of the pixel unit according to the size of the frame data; And And a luminance control driver for outputting a luminance control signal according to the information stored in the lookup table to adjust a ratio between an emission period and a non-emission period of the emission control signal. The method of claim 11, And the lookup table is applied to the current frame based on the information on the immediately previous frame. The method of claim 11, And the ratio of the emission period to the non-emission period of the pixel portion is determined according to the size of the frame data. A driving method of an organic light emitting display device for displaying an image in response to a data signal, a scanning signal, and a light emission control signal, When the ambient light is measured by an optical sensor and the ambient light is more than the reference value, the chroma signal of the input image data is changed to convert the data signal, and the ambient light is measured by the light sensor. A first step of adjusting a gamma value in response to ambient light; Generating the data signal in response to the converted video signal; And And a third step of adjusting the pulse width of the emission control signal by grasping the sum of the image data. The method of claim 14, The first step is Determining whether to change the input image data in response to a detection signal output from the optical sensor; Generating pixel chroma data corresponding to the input image data; And And extracting change data in response to the pixel saturation data and the switch signal. The method of claim 15, And storing the changed data in a memory. The method of claim 14, Generating frame data by summing video data input during one frame period; And And outputting a luminance control signal according to the pre-stored information corresponding to the frame data to adjust a ratio of the light emission period to the non-light emission period of the light emission control signal.

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