KR100658268B1 - Organic light emitting display device and control method of the same - Google Patents

Abstract

An organic light emitting display device and a control method thereof are provided to increase visibility and to reduce driving sensitivity by dissymmetrically setting the luminance regulating time of a pixel unit according to the change of the surrounding light. An organic light emitting display device includes a pixel unit(100) having plural scan lines(S1~Sn), plural data lines(D1~Dm), and plural pixels(50) formed in the regions where plural scan lines and plural data lines cross each other; a scan driving unit(300) transmitting a scan signal to the scan lines; a data driving unit(500) transmitting a data signal to the data lines; and a control unit(400) dissymmetrically setting the length of luminance regulation time of the pixel unit when the brightness of the surrounding light is changed from a first state to a second state brighter than the first state and from the second state to the first state.

Description

Organic light emitting display device and control method of the same

1 illustrates a structure of a conventional organic light emitting display device.

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

3 is a graph illustrating a time delay method according to the present invention.

4 is a diagram illustrating an example of a controller employed in an organic light emitting diode display according to the present invention.

5 is a diagram illustrating an example of an A-D converter employed in a control unit according to the present invention.

6 is a block diagram illustrating a time delay implementation according to an embodiment of the present invention.

*** Description of the main symbols in the drawings ***

400: control unit 420: timer

410: light sensing unit 430: brightness control unit

The present invention relates to an organic light emitting display device and a control method thereof, and more particularly, to an organic light emitting display device and a method for controlling the luminance adjustment time interval of the pixel unit asymmetrically according to the change in the illumination intensity of the ambient light. .

Recently, various flat panel display devices having a lighter weight and a smaller volume than the cathode ray tube have been developed. In particular, a light emitting display device having excellent luminous efficiency, brightness, viewing angle, and fast response speed has been attracting attention.

Such light emitting displays include organic light emitting diodes using organic light emitting diodes (OLEDs) and inorganic light emitting diodes using inorganic light emitting diodes (LEDs). The organic light emitting diode includes an anode electrode, a cathode electrode, and an organic light emitting layer which is disposed therebetween and emits light by a combination of electrons and holes. Inorganic light emitting diodes, unlike organic light emitting diodes, include an inorganic light emitting layer, for example, a light emitting layer made of a PN bonded semiconductor.

1 illustrates a structure of a conventional organic light emitting display device.

Referring to FIG. 1, a conventional organic light emitting display device includes a pixel unit 10, a power supply unit 20, a scan driver 30, and a data driver 40.

The pixel portion 10 is electrically connected to n scan lines S1, S2, ..., Sn arranged in the row direction and m data lines D1, D2, ... Dm arranged in the column direction. The plurality of pixels 5, the first power line L1 for supplying the first power supply ELVdd to the pixel portion 10, and the second power supply line L2 for transferring the second power supply ELVss. do. In this case, the second power supply line L2 is equivalently represented and may be formed in the entire region of the pixel portion 10 to be electrically connected to each pixel 5.

The power supply unit 20 transmits the first power supply ELVdd to the first power supply line L1, transfers the second power supply ELVss to the second power supply line L2, and transmits the first power supply to the pixel unit 100. The power source ELVdd and the second power source ELVss are supplied.

The scan driver 30 supplies a scan signal to the scan lines S1, S2,... Sn so that the pixels 5 included in the pixel unit 10 are selected by the scan signal and emit light.

The data driver 40 transmits a data signal corresponding to each grayscale to be displayed by the plurality of pixels 5 to the pixel unit 10.

In the conventional organic light emitting display having the above-described configuration, since the pixel 5 emits light at a constant brightness regardless of the brightness of the ambient light, when the image corresponding to the predetermined grayscale is displayed, the ambient light is displayed in a relatively dark illuminance. The sharpness of the displayed image is lowered at the illuminance where the brightness of the surroundings is brighter than the image.

Accordingly, an object of the present invention is to solve the above-described problems of the organic light emitting diode display, and an object of the present invention is to adjust the luminance of the pixel unit according to the ambient light, and to adjust the luminance of the pixel unit according to the change of the illumination of the ambient light. The present invention provides an organic light emitting display device and a control method thereof for increasing visibility by setting differently.

As a technical means for achieving the above object, one side of the present invention includes a pixel portion including a plurality of scan lines and a plurality of data lines and a plurality of pixels formed in an area where the plurality of scan lines and the plurality of data lines cross each other, A scan driver that transmits a scan signal to each of the plurality of scan lines, a data driver that transmits a data signal to each of the plurality of data lines, and a brightness of the ambient light changes from a first state to a darker state than the first state And a controller configured to asymmetrically set a time interval during which the luminance of the pixel unit is adjusted when the second state is changed from the second state to the first state.

Another aspect of the organic light emitting diode display according to the present invention comprises the steps of (a) setting the brightness adjustment time of the pixel portion corresponding to the case where the brightness of the ambient light changes from the first state to the second state darker than the first state, ( b) setting the luminance adjustment time of the pixel portion corresponding to the case where the ambient light changes from the second state to the first state, (c) outputting a detection signal corresponding to the brightness of the ambient light, Checking the change of the ambient light according to the detection signal, (d) selecting any one of step (a) or step (b) according to the result of step (c) and (e) the According to (a) to step (d) it provides a method for controlling an organic light emitting display device comprising the step of adjusting the luminance of the pixel portion.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

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

Referring to FIG. 2, the light emitting display device according to the present invention includes a pixel unit 100, a power supply unit 200, a scan driver 300, a controller 400, and a data driver 500.

The pixel portion 100 has a portion where n scan lines S1, S2, ..., Sn arranged in the row direction and m data lines D1, D2, ... Dm arranged in the column direction cross each other. A plurality of pixels 50 and a first power line L1 for supplying a first power supply ELVdd to the pixel unit 100 and a second power supply line L2 for transferring a second power supply ELVss are included. do. In this case, the second power supply line L2 is equivalently expressed and is formed in the entire region of the pixel portion 100 to be electrically connected to each pixel 50.

The power supply unit 200 transmits the first power supply ELVdd to the first power supply line L1, transfers the second power supply ELVss to the second power supply line L2, and transmits the first power supply to the pixel unit 100. The power source ELVdd and the second power source ELVss are supplied.

The scan driver 300 supplies a scan signal to the scan lines S1, S2,... Sn so that the pixels 50 included in the pixel unit 100 are sequentially selected by the scan signal and emit light.

The controller 400 adjusts the luminance of the pixel unit 100 according to the ambient light. That is, even in the dark illumination of the ambient light, the displayed image can be clearly recognized even if the luminance of the pixel unit 100 is low, so that the luminance of the pixel unit 100 is adjusted low by applying a low voltage. On the other hand, when the ambient light is bright and the luminance of the pixel unit 100 is high to recognize the displayed image clearly, the luminance of the pixel unit 100 is adjusted to a high level by applying a high voltage. The controller 400 includes a light detector 410, a timer 420, and a brightness controller 430.

The light detector 410 outputs a detection signal corresponding to the ambient light so that the luminance of the pixel unit 100 is adjusted according to the detection signal.

The timer 420 sets a different time interval for adjusting the luminance of the pixel unit 100 in accordance with a situation of changing the illuminance of the ambient light in the brightness boundary region in which the illuminance of the ambient light changes. That is, when the ambient light changes from the first state to the second state darker than the first state, the time required to adjust the luminance of the pixel unit 100 may change from the second state to the first state. In this case, the luminance of the pixel unit 100 is set to be shorter than the time required to adjust the luminance.

The brightness controller 430 generates a gamma correction signal corresponding to the ambient light and adjusts the data signal according to the generated gamma correction signal.

The data driver 500 transmits a data signal corresponding to each gray scale to be displayed by the plurality of pixels 50 to the pixel unit 100.

3 is a graph illustrating a time delay method according to the present invention.

Referring to FIG. 3, on the graph, reference numeral L3 shows the time required to adjust the luminance change and the luminance of the pixel portion in the situation where the ambient light changes from the bright illuminance to the dark illuminance. In this case, it is possible to know the time required for the luminance change and the brightness to be adjusted in the situation where the ambient light changes from the dark illuminance to the bright illuminance.

If the illuminance of the ambient light is divided into four stages of the first state, the second state, the third state, and the fourth state according to the brightness, and it is assumed that the brightness is brighter from the first state to the fourth state, For example, in the situation where the ambient light is changed from the second state to the third state, the delay time TD1 for adjusting the luminance of the pixel unit 100 from 100 candela (Cd) to 200 candela (Cd) is set as the ambient light. In the situation where the state changes from the third state to the second state, the luminance of the pixel unit 100 is set to be shorter than the delay time TD2 required to be adjusted from 200 candelas (Cd) to 100 candelas (Cd). That is, when the brightness of the ambient light changes from the first state to the fourth state direction, the time taken to adjust the brightness of the pixel unit 100 takes as much as TD1. When the brightness of the ambient light changes from the fourth state to the first state direction, The time taken to adjust the luminance of the pixel unit 100 takes as much as TD2. As described above, dividing the illuminance of the ambient light into the first state, the second state, the third state, and the fourth state is an example for explaining the embodiment according to the present invention in detail, and the illuminance of the ambient light may be performed in any of a plurality of steps. The above-described operation can be performed by dividing into.

On the other hand, the pixel unit 100 expresses an image with brighter brightness when the ambient light is relatively bright illuminance. Therefore, when the ambient light changes from the bright illuminance to the dark illuminance, the pixel portion 100 expresses high brightness and does not respond quickly to the ambient light, but the visibility is good. On the other hand, when the ambient light changes from dark illuminance to bright illuminance, when the ambient light does not brighten quickly in response to the ambient light, the visibility of the image expressed by the pixel unit 100 is degraded, and the change in luminance should correspond to the ambient light quickly. Therefore, the brightness adjustment time interval when the ambient light changes from the dark illumination to the bright illumination is shorter than the brightness adjustment time interval when the ambient light changes to the dark illumination. do.

4 is a diagram illustrating an example of a controller employed in an organic light emitting diode display according to the present invention.

Referring to FIG. 4, the brightness controller 430 included in the controller 400 includes an A / D converter 431, a counter 432, a conversion processor 433, a register generator 434, and a first selector. 435, a second selector 436, and a gamma correction unit 437.

The A / D converter 431 compares the analog sensing signal output from the light sensing unit 410 with a set reference voltage and outputs a digital sensing signal corresponding thereto. For example, the illumination intensity of the ambient light is divided into a plurality of stages of the first state, the second state, the third state, and the fourth state, and when the ambient light changes from the light intensity to the dark intensity, the reference voltages of each stage are set to VH1, Set to VM1 and VL1, respectively. When the ambient light changes from dark to bright illuminance, the reference voltages are set to VH3, VM3, and VL3 for each brightness level, and the reference voltages when the luminance of the pixel portion is not asymmetrically adjusted are VH2, VM2, Set to VL2. The reference voltage set as described above is compared with the analog sensing signal to output a sensing signal of '11' when the ambient brightness is the fourth state, and output a sensing signal of '10' when the ambient brightness is the third state. . In addition, when the ambient brightness is the second state, a detection signal of '01' is output, and when the ambient brightness is the first state, a detection signal of '00' is output. As described above, dividing the illuminance of the ambient light into the first state, the second state, the third state, and the fourth state is an example for explaining the embodiment according to the present invention in detail, and the illuminance of the ambient light may be performed in any of a plurality of steps. The above-described operation can be performed by dividing into.

The counter 432 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 432 referring to a binary value of 2 bits, the counter 432 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 432 again, the initialization state is reset. 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 433. In this case, the timer 420 includes a first timer 420a and a second timer 420b, and when the ambient light changes from dark to bright illuminance, a short time for adjusting the luminance of the pixel unit 100 is set. The first timer 420a is selected, and when the ambient light changes from bright illuminance to dark illuminance, the second timer 420a is selected in which the time for adjusting the luminance of the pixel unit 100 is set to be long. The timing signal Ts output from the selected first timer 420a or the second timer 420b is transmitted to the counter 432. In addition, the counter 432 controls the vertical synchronization signal Vsync in response to the timing signal Ts.

The conversion processor 433 maintains the detection signal output from the light detector 410 while the counter 432 counts a predetermined number. That is, when the counter 432 outputs the counting signal Cs, the sensing signal transmitted from the A / D converter 431 is output, and the sensing signal output by the counter 432 for one frame period is maintained. . When the next frame is reached, the detection signal is reset and the A / D converter 431 receives the detection signal and maintains the detection signal for one frame period. For example, the conversion processor 433 outputs a detection signal of '11' when the ambient light is in the fourth state and maintains it for one frame period that the counter 432 counts, and '00' if the ambient light is in the first state. The detection signal may be output and maintained for one frame period counted by the counter 432. In addition, when the ambient light is in the third state or the ambient light is in the second state, the sensing signals of '10' and '01' are output and maintained for one frame period, respectively, as in the above-described operation.

The register generator 434 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 435 selects a register set value corresponding to the control signal set by the conversion processor 433 from among a plurality of register set values stored in the register generator 434.

The second selector 436 receives a 1-bit setting value for controlling on and off from the outside, and when '1' is selected, the above-described brightness control unit 430 performs an operation, and '0' When selected, the brightness controller 430 is turned off to selectively control the brightness according to the ambient light.

The gamma correction unit 437 generates a plurality of gamma correction signals corresponding to the register setting values selected according to the detection signals held by the conversion processing unit 433.

5 is a diagram illustrating an example of an A / D converter employed in a control unit according to the present invention.

Referring to FIG. 5, the A / D converter includes first to third selectors 131, 132, and 133, first to third comparators 134, 135, and 136, and an adder 137.

The first to third selectors 131, 132, and 133 receive a plurality of gray voltages distributed through a plurality of resistors for generating a plurality of gray voltages VHI to VLO, and are set differently according to a change in brightness of ambient light. The gray level voltage corresponding to is outputted to determine the reference voltages VH to VL.

The first comparator 134 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 135 outputs the result of comparing the analog sense signal SA with the second reference voltage VM, and the third comparator 136 compares the analog sense signal SA with 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 137 adds all the result values output from the first to third comparators 134 to 136 and outputs them as a 2-bit digital sensing signal SD.

For example, the first reference voltage VH is set to 1V, the second reference voltage VM is set to 2V, and the third reference voltage VL is set to 3V, and the voltage value of the analog sensing signal SA is bright for ambient light. The A / D converter shown in FIG. 4 is assumed to be larger as follows. When the analog sense signal SA is smaller than 1 V, the first to third comparators 134 to 136 output '0', '0' and '0', respectively, so that the adder 137 is a digital of '00'. Output the detection signal SD. When the analog sense signal SA is between 1V and 2V, the first to third comparators 134 to 136 output '1', '0', and '0', respectively, so that the adder 137 is '01'. Outputs a digital detection signal (SD). In the same way, when the analog sense signal SA is between 2V and 3V, the adder 137 outputs a digital sense signal SD of '10', and when the analog sense signal SA is 3V or more, the adder ( 137 outputs a digital sensing signal SD of '11'.

6 is a block diagram illustrating a time delay implementation according to an embodiment of the present invention.

A description with reference to FIG. 6 is as follows. Implementation of the time delay method according to the present invention is implemented in the first step (ST100) to the seventh step (ST700).

The first step ST100 is to set the luminance adjustment time of the pixel portion corresponding to the case where the ambient light changes from a relatively dark illuminance to a bright illuminance. On the other hand, the illuminance of the ambient light may be arbitrarily divided into a plurality of stages, and may be applied at any stage if the ambient light changes from a relatively dark illuminance to a bright illuminance among the plurality of stages. In this case, the time required for the brightness of the pixel portion set in the first timer to be adjusted from a relatively low luminance to a high luminance is set in the second timer to be selected in a situation where the ambient light changes from a relatively bright illuminance to a dark illuminance. Make it shorter than the time required.

The second step ST200 is a step of setting the luminance adjustment time of the pixel portion corresponding to the case where the ambient light changes from bright illuminance to dark illuminance. In this case, the time required for the brightness of the pixel unit set in the second timer to be adjusted from a relatively high luminance to a low luminance is set in the first timer selected in a situation where the ambient light changes from a relatively dark illuminance to a bright illuminance. Set longer than required time.

The third step ST300 is a step of outputting a detection signal corresponding to the brightness of the ambient light and checking a change state of the ambient light according to the detection signal.

The fourth step ST400 is a step of selecting condition 1 or condition 2 according to the result of the third step ST300. For example, it is assumed that the ambient light is divided into the first state to the fourth state in the order of the brightness, and the brightness of the ambient light decreases from the first state to the fourth state. Condition 1 includes: (a) ambient light in a first state → second state; Third state; When changing to the fourth state: Check whether the current illuminance is in the second state, the third state, or the fourth state, (b) When the ambient light changes from the second state to the third state and the fourth state. : Check whether the current illuminance is in the third state or the fourth state. (C) When the ambient light changes from the third state to the fourth state: Check whether the current illuminance is in the fourth state. At this time, when the check result is (no), the detection signal output from the light detecting unit 410 is detected again.

The fifth step ST500 is a step of checking whether the given condition 2 is satisfied according to the result of the third step ST300. Condition 2 is (a) when the ambient light changes from the fourth state to the third state, the second state, and the first state: check whether the current illuminance is in the third state, the second state, or the first state, respectively. (b) When the ambient light changes from the third state to the second state and the first state: check whether the current illuminance is the second state or the first state, respectively, (c) The ambient light is in the second state → In case of changing to 1 state: Check whether the current illuminance is in the 1st state. At this time, when the check result is (no), the detection signal output from the light detecting unit 410 is checked again.

The sixth step ST600 is to drive the brightness controller when the result of the fourth step ST400 and the fifth step ST500 is YES.

The seventh step ST700 is a step of adjusting the luminance of the pixel unit in response to the control signal output according to the driving of the brightness controller performed in the sixth step ST600.

Although the technical idea of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above-described embodiment is for the purpose of description and not of limitation. In addition, it will be understood by those skilled in the art that various modifications are possible within the scope of the technical idea of the present invention.

According to the organic light emitting diode display and a control method thereof according to the present invention, visibility is increased by asymmetrically setting the time for adjusting the luminance of the pixel portion according to the change of ambient light, and the sensitivity of driving the device can be reduced.

Claims (8)

A pixel portion including a plurality of scan lines and a plurality of data lines and having a plurality of pixels formed in an area where the plurality of scan lines and the plurality of data lines cross each other; A scan driver transferring a scan signal to each of the plurality of scan lines; A data driver transferring a data signal to each of the plurality of data lines; And When the brightness of the ambient light changes from a first state to a second state that is brighter than the first state and when changing from the second state to the first state, the length of time that the luminance of the pixel portion is adjusted is asymmetric. An organic light emitting display device comprising a control unit set to. The method of claim 1, The interval of the luminance adjustment time when the ambient light changes from the second state to the first state is longer than the interval of the luminance adjustment time when the ambient light changes from the first state to the second state. Organic light emitting display set. The method of claim 1, The control unit A light detector for outputting a detection signal corresponding to ambient light; A timer configured to differently set the luminance adjustment time according to the detection signal and output a timing signal corresponding to the luminance adjustment time; And And a brightness controller configured to generate a gamma correction signal corresponding to the ambient light and adjust the data signal according to the gamma correction signal. The method of claim 3, wherein The timer is A first timer selected when the ambient light changes from a first state to a second state; And A second timer selected when the ambient light changes from the second state to the first state, And the luminance control time interval of the second timer is set longer than that of the first timer. The method of claim 3, wherein The brightness control unit A counter for counting a predetermined number during a period of one frame and generating a counting signal corresponding thereto; A conversion processor for holding the sense signal while the counter counts the predetermined number;  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 configured to select and output one register set value among the plurality of register set values in response to a sensing signal held by the conversion processor among the plurality of register set values stored in the register generator; And And a gamma correction circuit configured to generate a gamma correction signal corresponding to the detection signal. The method of claim 5, The brightness controller further includes a second selector that controls on and off of the brightness controller. (a) setting a luminance adjustment time of the pixel portion corresponding to the case where the brightness of the ambient light changes from the first state to the second state darker than the first state; (b) setting the luminance adjustment time of the pixel portion corresponding to the case where the ambient light changes from the second state to the first state; (c) outputting a detection signal corresponding to the brightness of the ambient light and checking a change of the ambient light according to the detection signal; (d) selecting any one of step (a) or step (b) according to the result of step (c); And (e) controlling the luminance of the pixel unit according to steps (a) to (d). The method of claim 7, wherein And the interval of the luminance adjustment time of step (a) is set to be shorter than the interval of the luminance adjustment time of step (b).

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