KR100893480B1 - Organic light emitting display and driving method teherof - Google Patents

Abstract

An object of the present invention is to provide an organic light emitting display device and a method of driving the same, which reduce power consumption by reducing power consumption of an optical sensor unit.

The present invention operates by receiving the drive power, the optical sensor unit for selecting and outputting the gamma correction value corresponding to the ambient light; An optical sensor controller for discontinuously transferring the driving power to the optical sensor unit; And a data driver configured to receive an image signal and generate a data signal corresponding to the image signal by using the selected gamma correction value, and a driving method thereof.

Description

Organic light emitting display device and driving method thereof {ORGANIC LIGHT EMITTING DISPLAY AND DRIVING METHOD TEHEROF}

The present invention relates to an organic light emitting display device and a driving method thereof. More particularly, the present invention relates to an organic light emitting display device and a driving method thereof so as to reduce power consumption of an optical sensor unit.

 A flat panel display arranges a plurality of pixels in a matrix form on a substrate, connects scan lines and data lines to each pixel, and selectively applies a data signal to the pixels to display an image.

A flat panel display is used as a display device such as a personal information terminal such as a personal computer, a mobile phone, a PDA, or a monitor for various information devices. An LCD using an LCD, an organic light emitting display using an organic light emitting diode, and a plasma panel PDPs and the like are known, and in particular, organic electroluminescent displays having excellent luminous efficiency, luminance, viewing angle, and fast response speed have been attracting attention.

1 is a structural diagram illustrating a structure of a general organic light emitting display device. Referring to FIG. 1, the organic light emitting display device includes a pixel unit 10, an optical sensor unit 20, a data driver 30, and a scan driver 40.

The pixel portion 10 includes a plurality of pixels 11, a plurality of scan lines S1, S2 ... Sn, and a plurality of data lines D1, D2 ... Dm. The pixel 11 includes a pixel circuit and an organic light emitting diode, and the pixel circuit is connected to the scan lines S1, S2 ... Sn and the data lines D1, D2 ... Dm to transfer scan signals and data signals. In response, the current corresponding to the data signal is transmitted to the organic light emitting diode (not shown). The organic light emitting diode includes an anode, a light emitting layer, and a cathode, and when a current flows from the anode toward the cathode, the gray scale is expressed in response to the current flowing through the light emitting layer.

The optical sensor unit 20 is a means for detecting ambient light and adjusting the brightness of each pixel 11 of the pixel unit 10 in response to the ambient light to improve visibility. That is, the light sensor unit 20 increases the luminance of the pixel unit 10 when the ambient light is bright and decreases the luminance of the pixel unit 10 when the ambient light is dark.

The data driver 30 is connected to the plurality of data lines D1, D2... Dm to transmit a data signal to the pixel unit 10. The data signal is generated by receiving an image signal and transferred to the pixel unit 10. In addition, the data driver 30 sets a gamma correction value differently in response to the optical detection signal transmitted from the optical sensor unit 20.

The scan driver 40 is connected to the plurality of scan lines S1, S2 ... Sn to transfer the scan signal to the pixel unit 10 so that the data signal is transferred to the row of the pixel unit 10 selected by the scan signal. do.

In the organic light emitting display device configured as described above, the brightness of the pixel unit may be adjusted by the optical sensor unit 20 to improve visibility and reduce power consumption. However, the optical sensor unit 20 continues to drive while the organic light emitting display device is driven, and thus the optical sensor unit 20 continues to consume power.

Therefore, the effect of reducing the power consumption according to the brightness control by the power consumed by the optical sensor unit 20 is not large, and even if the low-power optical sensor unit is used, such problems continue to appear. In particular, in the case of using a battery such as a mobile phone, when the power consumption is to be reduced to increase the use time, there is a concern that the optical sensor unit cannot be used due to the problem of power consumption.

Accordingly, an object of the present invention is to provide an organic light emitting display device and a driving method thereof having low power consumption.

The first aspect of the present invention for achieving the object of the present invention, the optical sensor unit for operating by receiving a drive power, and selecting and output the gamma correction value corresponding to the ambient light; An optical sensor controller for discontinuously transferring the driving power to the optical sensor unit; And a data driver configured to receive an image signal and generate a data signal corresponding to the image signal using the selected gamma correction value.

According to a second aspect of the present invention, there is provided a method of driving an organic light emitting display device, the method comprising: discontinuously detecting ambient light in an optical sensor; And adjusting the luminance according to the intensity of the ambient light detected by the optical sensor. In the step of detecting the ambient light discontinuously, the optical sensor is driven by receiving a driving voltage and is driven by a control signal. A driving method of an organic light emitting display device in which the driving voltage is discontinuously transmitted is provided.

According to the organic light emitting display device and the driving method thereof according to the present invention, since the optical sensor unit is not continuously driven, power consumption consumed by the optical sensor unit can be reduced.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a structural diagram illustrating a structure of an organic light emitting display device according to an exemplary embodiment of the present invention. Referring to FIG. 2, the organic light emitting display device includes a pixel unit 100, an optical sensor controller 200, an optical sensor unit 300, a data driver 400, and a scan driver 500.

The pixel unit 100 includes a plurality of pixels 101, a plurality of scan lines S1, S2... Sn, and a plurality of data lines D1, D2. The pixel 101 includes a pixel circuit and an organic light emitting diode, and the pixel circuit is connected to the scan lines S1, S2 ... Sn and the data lines D1, D2 ... Dm to transfer scan signals and data signals. In response, the current corresponding to the data signal is transmitted to the organic light emitting diode (not shown). The organic light emitting diode includes an anode electrode, a light emitting layer, and a cathode electrode, and when a current flows from the anode to the cathode electrode, the light emitting layer expresses a gray level in response to the current flowing.

The optical sensor control unit 200 is a means for switching the driving power for driving the optical sensor unit 300, and cuts off the driving power transmitted to the optical sensor unit 300 at regular time intervals. The time for which the driving power is cut off can be arbitrarily designated at the manufacturing stage. Therefore, since the optical sensor unit 300 operates by receiving the driving power discontinuously by the optical sensor control unit 200, the optical sensor unit 300 operates discontinuously. The discontinuous operation of the optical sensor unit 300 means that the operation and stop are repeated while the organic light emitting display device is driven, and the time when the optical sensor unit 300 is driven by the organic light emitting display device is driven. It is not to detect ambient light continuously, but to detect ambient light only at a set time. The detection time of the ambient light can be arbitrarily designated by the designer, and the organic light emitting display device is to be discontinuously operated regardless of the normal driving and standby modes.

The optical sensor unit 300 detects ambient light, selects a gamma correction value corresponding to the ambient light, and adjusts the brightness of each pixel 101 of the pixel unit 100 according to the ambient light by gamma correction. Means to lose. That is, the optical sensor unit 300 may increase the luminance of the pixel unit 100 by gamma correction when the ambient light is bright, and reduce the luminance of the pixel unit 100 by gamma correction when the ambient light is dark.

In addition, the optical sensor unit 300 receives the driving power discontinuously by the optical sensor control unit 200 to consume power only for the time for receiving the driving power. Therefore, the power consumed by the optical sensor unit 300 is reduced.

The data driver 400 is connected to the plurality of data lines D1, D2... Dm to transmit data signals to the pixel unit 100. The data driver 400 receives an image signal from the outside, generates a data signal, and transmits the image signal to the pixel unit 100. The data driver 400 includes a gamma correction circuit 410 and gamma corrects an image signal received through the gamma correction circuit 410. At this time, the gamma correction value used for gamma correction is determined according to the intensity of the ambient light, and thus the gamma correction is changed according to the intensity of the ambient light, and the luminance is changed by the gamma correction.

The scan driver 500 is connected to the plurality of scan lines S1, S2... Sn to transfer the scan signal to the pixel unit 100 so that the data signal is transferred to the pixel unit 100 selected by the scan signal.

3 is a structural diagram illustrating a structure of an optical sensor unit employed in the organic light emitting display device illustrated in FIG. 2. Referring to FIG. 3, the optical sensor unit 300 includes an optical sensor 311, an A / D converter 312, a counter 313, a conversion processor 314, a register generator 315, and a first sensor. A selector 316 and a second selector 317 are included. The signal output from the second selector 317 is transmitted to the gamma correction circuit 410.

The light detector 311 measures the brightness of the ambient light, divides the brightness of the ambient light into a plurality of stages, and outputs an analog detection signal corresponding to the brightness of each stage.

The A / D converter 312 compares the analog sensing signal output from the light sensing unit 311 with a set reference voltage and outputs a digital sensing signal corresponding thereto. For example, the A / D converter 312 outputs a sensing signal of '11' at a stage where the ambient brightness is the brightest, and outputs a sensing signal of '10' at a stage where the ambient 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 313 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 313 referring to a binary value of 2 bits, the counter 313 is initialized to '00' when the vertical sync signal Vsync is input, and then shifts the clock CLK signal in sequence. Count up to '11'. When the vertical synchronization signal Vsync is input to the counter 313 again, the initialization state is reset. In this manner, the counter 313 sequentially counts the numbers from '00' to '11' during one frame period. The counting signal Cs corresponding to the counted number is output to the conversion processor 314.

The conversion processor 314 outputs a control signal for selecting the set value of each register by using the counting signal Cs output from the counter 313 and the detection signal output from the A / D converter 312. That is, the conversion processing unit 314 outputs a control signal corresponding to the selected detection signal when the counter 313 outputs a predetermined signal and maintains the control signal output during the period of one frame by the counter. When the next frame is reached, the output control signal is reset and the control signal corresponding to the detection signal output from the A / D converter 312 is output again and maintained for one frame period. For example, the conversion processor 314 outputs a control signal corresponding to the detection signal of '11' when the ambient light is the brightest and maintains the control signal for one frame period counted by the counter 313. If the ambient light is the darkest state, a 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 313. 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 for one frame period, as in the above-described operation.

The register generator 315 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 316 selects a register set value corresponding to the control signal set by the conversion processor 314 from among a plurality of register set values stored in the register generator 315.

The second selector 317 receives a setting value of 1 bit for controlling on and off from the outside, and when '1' is selected, the second selector 317 receives a signal output from the first selector 316 and gamma correction circuit 410. When '0' is selected, the off voltage is output so that the brightness can be selectively controlled according to the ambient light.

The gamma correction circuit 410 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 314. At this time, the control signal corresponds to the detection signal output from the light sensing unit 311, so that the gamma correction signal has a different value according to the brightness of the ambient light. The above operation is performed for each of R, G, and B.

4 is a diagram illustrating an example of the gamma correction circuit shown in FIG. 2. Referring to FIG. 4, the gamma correction circuit 410 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 scale. It operates by including the 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 315 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 68 selects and outputs a gray scale voltage corresponding to a 4-bit register setting value among the gray voltages between the first selector 64 and the fourth selector 67.

The sixth selector 69 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 64 and the fifth selector 68. By the above operation, the curve adjustment of the intermediate gray scale portion is made possible according to 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 70 outputs a plurality of gray voltages corresponding to each of the plurality of gray levels to be displayed on the pixel unit 100.

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.

5 is a circuit diagram showing the structure of a pixel according to the present invention. Referring to FIG. 5, the pixel 101 includes a first transistor M1, a second transistor M2, a capacitor Cst, and an organic light emitting diode OLED.

The first transistor M1 has a source connected to the first power supply ELVDD, a drain connected to the organic light emitting diode OLED, and a gate connected to the first node N1 to correspond to the voltage of the first node N1. The driving current flows from the source to the drain.

The second transistor M2 has a source connected to the data line Dm, a drain connected to the first node N1, and a gate connected to the scan line Sn to correspond to a scan signal transmitted through the scan line Sn. The data signal flowing through the data line Dm is transmitted to the first node N1.

In the capacitor Cst, the first electrode is connected to the first power source ELVDD and the second electrode is connected to the first node N1 to maintain the voltage of the first node N1.

The organic light emitting diode OLED includes an anode electrode, a cathode electrode and a light emitting layer positioned between the anode electrode and the cathode electrode, the anode electrode is connected to the drain of the first transistor M1 and the cathode electrode is the first power source ELVDD. It is connected to a second power supply ELVSS having a lower voltage. When the current flows from the anode electrode toward the cathode electrode, the brightness is changed according to the amount of current flowing to express the gray scale.

While preferred embodiments of the present invention have been described using specific terms, such descriptions are for illustrative purposes only and it is understood that various changes and modifications may be made without departing from the spirit and scope of the following claims. You must lose.

1 is a structural diagram illustrating a structure of a general organic light emitting display device.

2 is a structural diagram illustrating a structure of an organic light emitting display device according to an exemplary embodiment of the present invention.

3 is a structural diagram illustrating a structure of an optical sensor unit employed in the organic light emitting display device illustrated in FIG. 2.

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

5 is a circuit diagram showing the structure of a pixel according to the present invention.

Claims (7)

An optical sensor unit operating by receiving driving power and selecting and outputting a gamma correction value corresponding to ambient light; An optical sensor controller for discontinuously transferring the driving power to the optical sensor unit; And And a data driver configured to receive an image signal and generate a data signal corresponding to the image signal using the selected gamma correction value. The method of claim 1, The optical sensor unit An optical sensing unit configured to output an analog sensing signal corresponding to the brightness of the ambient light; An analog-digital converter for converting the analog sense signal 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 steps and storing a plurality of the correction values corresponding to each step; A first selector for selecting and outputting one correction value in response to the control signal set by the conversion processing unit among the plurality of correction values stored in the register generation unit; And And a second selector configured to output one of the correction value and a predetermined signal output from the first selector. The method of claim 2, The data driver, And a gamma correction circuit configured to generate a gamma correction signal in response to the signal output from the second selector. delete In a method of driving an organic light emitting display device, Discontinuously detecting ambient light in an optical sensor; And Comprising the step of adjusting the brightness in response to the intensity of the ambient light detected by the optical sensor,  In the step of detecting the ambient light discontinuously, the optical sensor is driven by receiving a driving voltage, the driving voltage is discontinuously transmitted by a control signal. delete The method of claim 5, wherein And adjusting the luminance, wherein the luminance is adjusted by changing a gamma correction value.

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