KR100812000B1 - Organic light emitting display device and driving method thereof - Google Patents

Abstract

The present invention provides a pixel unit including a plurality of pixels representing a plurality of scan signals, a plurality of emission control signals, and a plurality of data signals to represent an image. Is a memory formed by modifying the n-1th frame by receiving a portion corresponding to the difference with the video data transmitted in the n-1th frame, and adjusts the luminance limitation range of the pixel unit, wherein the luminance of the nth frame is adjusted. The limiting range includes a luminance controller adjusting the first frame data formed by the video data transmitted in the n-th frame and the second frame data formed by the video data transmitted in the n-th frame, and the pixel unit. A scan driver for transmitting the light emission control signal whose pulse width is adjusted according to the scan signal and the luminance limit range; The present invention provides an organic light emitting display device including a data driver which generates the plurality of data signals using video data stored in the memory and transfers the plurality of data signals to the pixel unit.

Description

Organic electroluminescent display and driving method thereof {ORGANIC LIGHTING EMITTING DIODE DISPLAY DEVICE AND DRIVING METHOD THEREOF}

1 is a conceptual diagram illustrating a display unit of an organic light emitting display device according to the related art.

2 is a conceptual diagram illustrating a display unit of an organic light emitting display device according to the present invention.

FIG. 3 is a structural diagram showing a data structure of a video data signal transferred to the memory shown in FIG.

4 is a conceptual diagram illustrating an embodiment of a luminance controller employed in an organic light emitting display device according to the present invention.

5 is a conceptual diagram illustrating a process of generating frame data in the organic light emitting display device according to the present invention.

The present invention relates to an organic light emitting display device and a driving method thereof. More specifically, the present invention provides an organic light emitting display device and a method of driving the same, which reduce power consumption and improve contrast by limiting luminance according to an emission ratio. will be.

Recently, various flat panel display devices having a smaller weight and volume than the cathode ray tube have been developed. The flat panel display device responds to a selective scan signal by connecting a scan line and a data line to a plurality of pixels in a matrix form formed on a substrate. Drive by a method of applying a data signal to display an image.

The flat panel display is classified into a passive matrix display device and an active matrix display device according to its driving method, and an active matrix display device has advantages in terms of dual resolution, contrast, and response speed. There is this.

Such 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 of various information devices, and includes an LCD using a liquid crystal panel, an organic light emitting display using an organic light emitting element, and a plasma panel. PDPs and the like are known, and in particular, an organic light emitting display device having excellent luminous efficiency, luminance, viewing angle, and quick response time has been attracting attention.

1 is a conceptual diagram illustrating a display unit of an organic light emitting display device according to the related art. Referring to FIG. 1, the light emitting display device according to the related art includes a pixel unit 10, a data driver 20, a scan driver 30, and a power supply 40.

In the pixel unit 10, a plurality of pixels 11 are arranged and a light emitting element (not shown) is connected to each pixel 11. And n scan lines S1, S2, ... Sn-1, Sn formed in the row direction and transmitting the scan signal, and m data lines D1, D2, forming the column direction and transmitting the data signal. M m power supplies for transmitting the first power supply (Dm-1, Dm) and the first power supply (not shown) and second power supply ELVSS having a lower potential than the first power supply (ELVDD). 2 power supply lines (not shown) are arranged. The pixel unit 10 emits light by the scan signal, the data signal, the first power source ELVDD, and the second power source ELVSS to display an image.

The data driver 20 is a means for applying a data signal to the pixel unit 10. The data driver 20 is connected to the data lines D1, D2,... Dm-1, Dm of the pixel unit 10. Connected to apply a data signal to the pixel portion 10.

The scan driver 30 is a means for sequentially outputting scan signals. The scan driver 30 is connected to the scan lines S1, S2,... Pass in a line. The data signal input from the data driver 20 is applied to a specific row of the pixel unit 10 to which the scan signal is transmitted to display an image. When all rows are sequentially selected, one frame is completed.

The power supply unit 40 transfers the first power source ELVDD and the second power source ELVSS having a potential lower than that of the first power source ELVDD and the first power source ELVDD to the pixel unit 10. The current corresponding to the data signal flows in each pixel 10 by the voltage difference of the ELVSS.

In the organic light emitting display device configured as described above, when the high luminance is expressed, a large amount of current flows in the pixel portion 10, and when the low luminance is expressed, a small current flows in the pixel portion 10. In this case, when a large amount of current flows in the pixel unit 10 under high brightness, a large load is applied to the power supply unit 40, so that the power supply unit 40 needs to have a high output.

In addition, when there are many regions expressing high brightness, contrast and the like may be degraded due to glare or the like, resulting in a deterioration of image quality.

Therefore, the present invention was created to solve the problems of the prior art, the object of the present invention is to limit the amount of current flowing when the area expressing high brightness in the entire light emitting area is large to reduce the overall brightness to reduce the power consumption The present invention provides an organic light emitting display device and a driving method thereof for improving the image quality.

In order to achieve the above object, an organic light emitting display device according to an embodiment of the present invention includes a pixel unit including a plurality of pixels expressing an image by receiving a plurality of scan signals, a plurality of light emission control signals, and a plurality of data signals, and a frame from the outside. The video data is received and stored in units, and the nth frame is a memory formed by modifying the n-1th frame by receiving a portion corresponding to a difference between the video data transmitted in the n-1th frame and the pixel unit. The luminance limit range is adjusted, and the luminance limit range of the nth frame is the first frame data formed by the video data transmitted in the n-1th frame and the second frame formed by the video data transmitted in the nth frame. A luminance control unit for adjusting the data in response to data; Provided is an organic light emitting display device including a scan driver for transmitting the emission control signal of the width is adjusted and a data driver for generating the plurality of data signals using the video data stored in the memory and then transmitting the plurality of data signals to the pixel unit. It is.

An organic light emitting display device according to the present invention for achieving the above object is a pixel portion including a plurality of pixels for receiving an image by receiving a plurality of scan signals, a plurality of light emission control signals and a plurality of data signals, from outside The video data is received and stored in a frame unit, and the n th frame is a memory formed by modifying the n-1 th frame by receiving a portion corresponding to a difference between the video data transmitted in the n-1 th frame and the pixel. Adjust a negative luminance limit range, wherein the luminance limit range of the nth frame is the first frame data formed by the video data transmitted in the n-1th frame and the second data formed in the nth frame. A luminance adjusting unit for adjusting the frame data, a scan driver transferring the scan signal to the pixel unit, and the luminance unit An emission control driver for transmitting the emission control signal whose pulse width is adjusted according to a range, and a data driver for generating the plurality of data signals using video data stored in the memory and transmitting the generated data signals to the pixel unit. An electroluminescent display device is provided.

A driving method of an organic light emitting display device according to the present invention for achieving the above object is a driving method of an organic light emitting display device comprising a pixel representing an image in response to a data signal, a scanning signal and a light emission control signal. ,
In the n-th frame, transmitting only the video signal corresponding to the difference portion in the n-1th frame, the first area corresponding to the same portion as the n-1th frame and the difference between the n-1th frame Determining a second area corresponding to a portion of the pixel; summing the gray value of the data signal input to the first area and adding the gray value of the data signal input to the second area to determine the emission rate of the pixel; A method of driving an organic light emitting display device, the method comprising: adjusting the light emission time of the pixel in response to the light emission rate.

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

2 is a conceptual diagram illustrating a display unit of an organic light emitting display device according to the present invention. Referring to FIG. 2, the light emitting display device includes a pixel unit 100, a memory 200, a brightness controller 300, a data driver 400, a scan driver 500, and a power supply 600. .

In the pixel unit 100, a plurality of pixels 110 are arranged and a light emitting element (not shown) is connected to each pixel 110. And n scan lines S1, S2, ... Sn-1, Sn that are formed in a row direction and transmit scan signals, and n light emission control signal lines E1, E2, ... En that transfer emission control signals. -1, En), m data lines D1, D2, .... Dm-1, Dm formed in the column direction and transmitting the data signal, and a first power source delivering the first power source ELVDD to the pixel. The line L1 and the second power supply line L2 for transmitting the second power supply ELVSS to the pixel are arranged. In this case, the second power line L2 may be equivalently represented, and may be formed in the entire region of the pixel unit 100 to be electrically connected to each pixel 110.

The memory 200 receives a video data signal from the outside and stores the data signal in units of frames. The video data signal transmitted from the outside allows only the portion that is different from the data of the previous frame to be transmitted. Therefore, the memory 200 stores the video data of one frame and receives only the part that is different from the previous frame in the next frame, and corrects only the part that is different from the previous frame in the next frame. Stores video data input to a frame.

The luminance adjusting unit 300 outputs a luminance control signal to limit the luminance so that the luminance of the pixel unit 100 representing the image does not exceed a predetermined level. The luminance of the pixel unit 100 is expressed higher than the case where the area of light emitted by the high luminance in the pixel unit 100 is large when the area of light emitted by the high luminance in the pixel unit 100 is small. For example, when the pixel unit 100 emits light in full white, the pixel unit 100 has higher luminance than otherwise. Therefore, when the area emitting light with high luminance as described above is large, the luminance is reduced to some degree. At this time, the luminance is changed according to the change of the area emitting light at a high luminance by varying the range in which the luminance is limited according to the area emitting light at a high luminance.

The brightness controller 300 determines the size of the frame data, which is the sum of the video data signals input in one frame, and determines that the amount of current flowing to the pixel unit 100 that emits light brightly when the size of the frame data is large is determined. If the sum is small, it is determined that the amount of current flowing through the pixel portion 100 is small. Therefore, the brightness controller 300 outputs a brightness control signal to limit the brightness when the size of the frame data signal is greater than or equal to a predetermined value, thereby reducing the overall brightness of the image represented by the pixel unit 100 to display the display. Do it.

However, when the video data input from the outside is transmitted only the part that is different from the previous frame, when the frame data is generated using only the difference part, the wrong frame data is generated, thereby adjusting the luminance appropriate for the overall brightness of the frame. You won't lose.

When the brightness of the pixel unit 100 is limited by the brightness controller 300, the amount of current flowing through the pixel unit 100 is limited, thereby eliminating the need for a high output power supply unit 600. In addition, when the luminance of the pixel unit 100 is not limited, the time for emitting the pixels to emit light is maintained for a long time, thereby increasing the luminance, thereby increasing the contrast ratio of the pixels to emit light and the pixels not to emit light. Thus, the contrast ratio of the pixel portion 100 is improved.

In this case, as a method of reducing the amount of current flowing in the pixel portion 100, when the pixel emits light, the amount of current flowing in the pixel portion 100 may be reduced by reducing the time for supplying the current.

The luminance adjusting unit 300 adjusts the pulse width of the emission control signal transmitted through the emission control signal lines E1, E2, ... En-1, En to adjust the time for which the pixel unit 100 emits light. If the pulse width is long by adjusting the light emission time to emit light within one frame, the amount of current flowing into the pixel portion 100 increases, so that the overall luminance of the pixel portion 100 does not decrease, and if the pulse width is short, the pixel portion ( The amount of current flowing into the device 100 is reduced so that the overall luminance of the pixel unit 100 is lowered. .

The data driver 400 is a means for applying a data signal to the pixel unit 100. The data driver 400 receives video data having red, blue, and green components from the memory 200 to generate a data signal. The data driver 400 applies a data signal generated by being connected to the data lines D1, D2,... Dm-1, Dm of the pixel unit 100 to the pixel unit 100.

The scan driver 500 is a means for applying a scan signal and a light emission control signal to the pixel unit 100. The scan driver 500 includes scan lines S1, S2, ... Sn-1, Sn and a light emission signal line E1. , E2, ... En-1, En) to transmit a scan signal and a light emission control signal to a specific row of the pixel unit 100. The data signal output from the data driver 400 is transmitted to the pixel 110 to which the scan signal is transmitted, and the pixel 110 to which the emission control signal is transmitted emits light according to the emission control signal.

The scan driver 500 may be divided into a scan driver circuit for generating a scan signal and a light emitting driver circuit for generating a light emission control signal, and the scan driver circuit and the light emitting driver circuit may be included in one component part and may be separate. It may be separated into components.

The data signal input from the data driver 300 is applied to a specific row of the pixel unit 100 to which the scan signal is transmitted, and a current corresponding to the data signal is transferred to the light emitting control signal so that the image is emitted by the light emitting device. Is displayed. At this time, if all the rows are sequentially selected, one frame is completed.

The power supply unit 600 transfers the first power source ELVDD and the second power source ELVSS to the pixel unit 400, and thus the data signal is transmitted at each pixel due to the difference between the first power source ELVDD and the second power source ELVSS. Allow current to flow. In this case, the amount of current flowing through the pixel unit 100 is limited by the brightness controller 300 to reduce power consumed by the pixel unit 100, thereby reducing the size of the power supply unit 600.

FIG. 3 is a structural diagram showing a data structure of a video data signal transferred to the memory shown in FIG. Referring to FIG. 3, the data structure of the video data signal includes an instruction code unit 410 for identifying the type of the video data signal, and an address for knowing which region of the frame the video data signal is input to. And a data signal unit 430 to which a video data signal is input.

The command code unit 410 is a part for identifying the transmitted video data signal, and the command code unit 410 is used to decode the video data signal.

The address unit 420 stores information for identifying a start point and an end point in a frame so as to determine in which part of the memory the video data is to be stored.

The data signal unit 430 stores video data representing an image and is stored in a specific area of the memory according to a time point and an end point stored in the address unit 420 to be used for generating a data signal.

4 is a conceptual diagram illustrating an embodiment of a luminance controller employed in an organic light emitting display device according to the present invention. Referring to FIG. 4, the luminance controller 300 includes a data analyzer 310, a data adder 320, a lookup table 330, and a luminance control driver 340.

The data analyzer 310 determines the viewpoint and the end point by the address unit in the data structure of the video data signal so as to determine the area of the portion that is different from the previous frame and the area of the portion that does not differ from the previous frame.

The data summing unit 320 extracts information on frame data obtained by summing video data having information on red, blue, and green input to one frame. In the frame data, all the video data for one frame are summed up. If the data value of the frame data is large, the data includes a lot of high grays. If the data value of the frame data is small, the data of the high grays is small. It can be seen that. That is, the emission rate of the pixel portion can be determined according to the size of the frame data. Luminescence is defined by Equation 1 below.

At this time, the data summing unit 320 grasps the video data delivered to the current frame (n-th frame), generates first frame data using the video data delivered to the previous frame (n-1th frame), and then generates the current frame. The second frame data is generated using the video data transferred to the. The emission rate is determined according to the area occupied by the first frame data, the second frame data, and the respective frame data in the current frame.

The emission rate is generated using the first frame data and the second frame data according to Equation 2 below.

Here, n-1 frame data refers to video data representing an n-1 th frame, and n frame data refers to video data transmitted in n frames. In addition, the predetermined area means the area of the second frame identified by the time point and the end point identified by the address unit.

In the lookup table 330, the light emission period of the light emission control signal is designated according to the data value of the light emission rate. In addition, the width of the light emitting section is specified using the upper bits of the light emitting rate so as to reduce the size of the lookup table 330. For example, the width of the light emission period is determined in correspondence with the upper five bits of the data value of the light emission rate.

As the size of the light emission rate increases, the luminance of the pixel unit 100 gradually increases, and when the luminance exceeds a predetermined brightness, the luminance of the pixel unit 100 is limited. In addition, as the luminance of the pixel unit 100 increases, a ratio that is gradually limited is further increased to prevent an excessive increase in the luminance of the pixel unit 100.

At this time, if the luminance is uniformly limited in accordance with the increase in the luminance of the pixel portion 100, the luminance of the pixel portion 100 may be excessively limited by the limitation of the luminance when the luminance is very high. It doesn't provide a bright screen and simply drops the overall brightness. Therefore, by setting a range that limits the luminance to the maximum, a range that is limited when the entire pixel portion 100 represents white is prevented from falling below a range that limits the luminance limitation of the pixel portion 100.

If the size of the frame data does not exceed the predetermined size, the luminance is not limited. If the luminance is not high, the luminance is not limited.

5 is a conceptual diagram illustrating a process of generating frame data in the organic light emitting display device according to the present invention. a represents the n-1th frame and b represents the nth frame.

First, a denotes a state in which the total sum of video data representing the n-th frame is 100, and b denotes that the total sum of video data representing the n-th frame represents 120. In this case, it is assumed that the n-th frame has a partial area that is different from the n-1th frame occupies an area of 1/10 of one frame. The sum of the video data of the parts having the difference is 30 in the n-1th frame and 50 in the nth frame. Therefore, the video data input in the nth frame is delivered with only the difference part from the outside, and when the sum of the video data transferred from the outside is 50, the nth frame is brighter than the n-1th frame. In addition, there is a fear that the brightness control unit will recognize a very dark frame. Therefore, 95 is obtained by substituting Equation 2 above and obtaining the sum of the n-th frame data. When the frame data is 95, the frame data of the n-th frame originally corresponds to 120, but the error is smaller than that of adding only the video data input from the outside.

According to the organic light emitting display device and the driving method thereof according to the present invention, the power consumption can be reduced in the organic light emitting display device, the manufacturing cost can be reduced by reducing the size of the power supply. And contrast can be raised and visibility can be made high.

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.

Claims (13)

A pixel unit including a plurality of pixels that receive a plurality of scan signals, a plurality of emission control signals, and a plurality of data signals to represent an image; A memory configured to receive and store video data from the outside in units of frames, wherein the nth frame is formed by modifying the n-1th frame by receiving a portion corresponding to a difference from the video data transmitted in the n-1th frame; The luminance limit range of the pixel unit is adjusted, and the luminance limit range of the nth frame is formed by first frame data formed by video data transmitted in the n-1th frame and video data transmitted in nth frame. A brightness controller for adjusting the second frame data; A scan driver for transmitting the light emission control signal whose pulse width is adjusted according to the scan signal and the luminance limitation range to the pixel unit; And And a data driver which generates the plurality of data signals using the video data stored in the memory and transfers the plurality of data signals to the pixel unit. The method of claim 1, And the second frame data corresponds to a difference from the first frame data. The method of claim 1, And the luminance limit range is determined in correspondence to the area of the image formed by the first frame data and the area of the image formed by the second frame data. The method of claim 1, The brightness control unit, A data analyzer to determine an area of an image formed by the second frame data; The area of the image formed by the first frame data in the nth frame and the image formed by the second frame data correspond to the area of the image formed by the second frame data determined by the data analyzer. A data summing unit that grasps an emission rate of the nth frame using an area; A lookup table in which a pulse width of the light emission control signal is specified in correspondence with the light emission rate determined by the data summing unit; And And a luminance control driver for outputting a control signal corresponding to the pulse width of the emission control signal. The method of claim 1, And a time period during which the pixel unit emits light by the pulse width of the emission control signal. A pixel unit including a plurality of pixels that receive a plurality of scan signals, a plurality of emission control signals, and a plurality of data signals to represent an image; A memory configured to receive and store video data from the outside in units of frames, wherein the nth frame is formed by modifying the n-1th frame by receiving a portion corresponding to a difference from the video data transmitted in the n-1th frame; The luminance limit range of the pixel unit is adjusted, and the luminance limit range of the nth frame is formed by first frame data formed by video data transmitted in the n-1th frame and video data transmitted in nth frame. A brightness controller for adjusting the second frame data; A scan driver transferring the scan signal to the pixel unit; A light emission control driver for transmitting the light emission control signal whose pulse width is adjusted according to the luminance limit range; And And a data driver which generates the plurality of data signals using the video data stored in the memory and transfers the plurality of data signals to the pixel unit. The method of claim 6, The second frame data is a portion corresponding to a difference from the first frame data. The method of claim 6, And the luminance limit range is determined in correspondence to the area of the image formed by the first frame data and the area of the image formed by the second frame data. The method of claim 8, And the video data includes information about a viewpoint and an end point in one frame, and grasps an image area formed by the second frame data based on the viewpoint and the end point. The method of claim 6, The brightness control unit, A data analyzer to determine an area of an image formed by the second frame data; The area of the image formed by the first frame data in the nth frame and the image formed by the second frame data correspond to the area of the image formed by the second frame data determined by the data analyzer. A data summing unit that grasps an emission rate of the nth frame using an area; A lookup table in which a pulse width of the light emission control signal is specified in correspondence with the light emission rate determined by the data summing unit; And And a luminance control driver for outputting a control signal corresponding to the pulse width of the emission control signal. The method of claim 6, And a time period during which the pixel unit emits light by the pulse width of the emission control signal. A driving method of an organic light emitting display device comprising a pixel representing an image in response to a data signal, a scanning signal, and a light emission control signal. transmitting only an image signal corresponding to a difference part in an n−1 th frame in an n th frame; Identifying a first area corresponding to the same part as the n-1th frame and a second area corresponding to a part different from the n-1th frame; Summing the gradation values of the data signals input to the first area and summing the gradation values of the data signals input to the second area to determine the light emission rate of the pixel; and A method of driving an organic light emitting display device, the method comprising adjusting a light emitting time. The method of claim 12, And a light emission time of the pixel is controlled by a pulse width of a light emission control signal.

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