KR20180024376A - Organic light emitting display device - Google Patents

Abstract

According to the present invention, provided is an organic light emitting display apparatus, which comprises: a panel having subpixels defined by gate lines and data lines; a data driver for supplying data voltage to the data lines; a gate driver for supplying gate pulses to the gate lines; and a controller for controlling the data driver and the gate driver. Therefore, during an initialization period introduced after a sensing period among a blank period, VRPRE supplied to a sensing line can be variable in accordance with black data voltage supplied to data lines during the initialization period.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light-

The present invention relates to an organic light emitting display, and more particularly, to an organic light emitting display capable of performing external compensation through a sensing line.

Flat panel display devices (FPDs) are used in various types of electronic products including mobile phones, tablet PCs, and notebook computers. In recent years, an electrophoretic display device (EPD: Electrophoretic Display Device) has been widely used as a liquid crystal display device (LCD) and an organic light-emitting display device (OLED) .

In particular, the organic light emitting diode (OLED) uses a self-luminous element that emits light by itself, and thus has advantages such as a fast response speed, a high luminous efficiency, a high luminance, and a large viewing angle.

In the organic light emitting diode display, a characteristic deviation such as a threshold voltage (Vth) and mobility of the driving transistor occurs for each pixel for reasons of process variation, deterioration and the like. Therefore, the amount of current for driving each of the organic light emitting diodes is different, thereby causing a luminance deviation between the pixels.

In order to solve the above problem, Korean Patent Laid-Open Publication No. 10-2013-0066449 (hereinafter referred to as "Prior Art Document") discloses a technique for compensating for a change in characteristics of driving transistors included in each pixel through correction of input image data An external compensation method is disclosed.

FIG. 1 is a diagram illustrating a phenomenon in which a first line of a panel applied to a conventional organic light emitting display is displayed dark during an initialization period after a sensing period.

In the conventional organic light emitting display, sensing for external compensation is performed during a blank period during one frame period, and in particular, the sensing is performed during a sensing period during the blank period.

During the initialization period after the sensing period during the blanking period, high-level pre-voltages are supplied through the sensing lines connected to the sensing transistor. Accordingly, the first node between the driving transistor and the organic light- . The first node is connected to the source of the driving transistor.

During the initialization period, a high-level black data voltage is supplied to the data lines. In this case, the first node voltage rises and falls with the black data voltage due to a kick-back phenomenon caused by the black data voltage.

When the voltage of the first node is increased, the gate-source voltage (Vgs) of the driving transistor is lowered. When the gate-source voltage Vgs of the driving transistor is lowered, the amount of current supplied to the organic light emitting diode connected to the driving transistor is reduced, and thus the brightness of the organic light emitting diode is reduced.

The above-described phenomenon is generated in the first horizontal line 1HL provided at the top of the panel 10. [

Described in detail, after the sensing period, in the initialization period, the brightness of the subpixels disposed in the first horizontal line 1HL is reduced by the kickback phenomenon. Accordingly, as shown in FIG. 1, the first horizontal line provided in the display area 11 of the panel 10 appears dark.

SUMMARY OF THE INVENTION It is an object of the present invention, which is proposed to solve the above-mentioned problems, to provide a method of driving a plasma display panel in which, during an initialization period that comes after a sensing period during a blank period, Emitting device according to the present invention.

According to an aspect of the present invention, there is provided an organic light emitting diode (OLED) display device including a panel having subpixels defined by gate lines and data lines, a data driver supplying data voltages to the data lines, A gate driver for supplying gate pulses to the gate lines, and a control unit for controlling the data driver and the gate driver. Each of the subpixels includes: a switching transistor connected to a gate line and a data line; A driving transistor for controlling a magnitude of a current output to the organic light emitting diode according to a data voltage transmitted through the switching transistor, and a second node between the driving transistor and the organic light emitting diode And a sensing transistor connected to the sensing line and being turned on or off by a sensing pulse and sensing a characteristic of the driving transistor during a sensing period during a blank period. Wherein the data driver supplies the free voltage to the sensing line during an initialization period which is issued after the sensing period during the blank period and supplies the black data voltage to the data lines for a period shorter than the period during which the free voltage is supplied Supply. The data driver varies the alkaline voltage according to the black data voltage.

The luminance of the subpixels provided in the first horizontal line of the panel is reduced by the black data voltage that is conventionally supplied to the data lines in the initializing period that comes after the sensing period during the blank period. This phenomenon is called a kickback phenomenon.

However, according to the present invention, since the alkaline voltage supplied to the sensing line connected to each subpixel varies according to the black data voltage, the kickback phenomenon can be prevented.

Particularly, in the present invention, when the black data voltage is increased, the all pre-voltage is polled and then increased. Accordingly, in each of the subpixels provided in the first horizontal line of the panel, the voltage of the first node between the driving transistor and the organic light emitting diode is not fluctuated by the black data voltage, The brightness of the subpixels is not reduced.

More specifically, when the black data voltage is increased to a high level, the voltage of the first node is not shaken by momentarily polling and rising the free voltage, so that the first The luminance of the sub-pixels provided in the horizontal line is not reduced.

FIG. 1 is a diagram illustrating a phenomenon in which a first line of a panel applied to a conventional organic light emitting display is displayed dark during an initialization period after a sensing period. FIG.
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an organic light emitting diode (OLED) display device.
4 is a view illustrating a structure of a subpixel formed on a panel applied to an OLED display according to an embodiment of the present invention.
FIG. 5 is a diagram illustrating a configuration of a control unit applied to an organic light emitting display according to the present invention; FIG.
6 is a diagram illustrating a configuration of a data driver applied to an organic light emitting display according to an embodiment of the present invention.
7 is a diagram illustrating waveforms of signals applied to an organic light emitting display according to an embodiment of the present invention.

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

It should be noted that, in the specification of the present invention, the same reference numerals as in the drawings denote the same elements, but they are numbered as much as possible even if they are shown in different drawings.

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

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

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

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

The term " at least one " should be understood to include all possible combinations from one or more related items. For example, the meaning of 'at least one of the first item, the second item and the third item' means not only the first item, the second item or the third item, but also the second item, the second item and the third item, Means any combination of items that can be presented from more than one.

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

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

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention can be applied to various kinds of display devices using external compensation. Hereinafter, for convenience of explanation, an organic light emitting display device will be described as an example of the present invention.

FIG. 2 is a view schematically showing a configuration of an organic light emitting diode display according to the present invention, and FIG. 3 is an exemplary view showing an arrangement structure of subpixels formed on a panel applied to the organic light emitting diode display according to the present invention And FIG. 4 is a view illustrating a structure of subpixels formed on a panel applied to the organic light emitting diode display according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

First, the object of the present invention is to prevent a reduction in the luminance of the first horizontal line due to the kickback phenomenon by changing the waveform of the all-around voltage VRPRE supplied through the sensing line SL. Hereinafter, the horizontal line means a line formed by the sub-pixels 110 arranged along the gate line. Accordingly, the first horizontal line means a line formed by the sub-pixels 110 arranged along the first gate line GL1 in FIG.

For example, as shown in FIG. 1, a defect in which the luminance of the first horizontal line 1HL of the panel 10 in the conventional organic light emitting display device is reduced is smaller than that of the sub- The gate-source voltage Vgs of the driving transistors included in the sub-pixels of the other horizontal lines becomes smaller than the gate-source voltage Vgs of the driving transistors included in the sub-pixels of the other horizontal lines.

The reason why the gate-source voltage Vgs of the driving transistors of the first horizontal line is reduced is that the voltage at the first node between the driving transistor and the organic light emitting diode is shaken by a kickback phenomenon to be. The first node is connected to a sensing transistor that performs a sensing function for external compensation. The voltage of the first node is shaken because a kickback phenomenon occurs due to the overlap capacitance between the sensing line to which the sensing transistor is connected and the data line.

As described above, an object of the present invention is to change the waveform of the voltage VRPRE to prevent or minimize the kickback phenomenon.

Second, in order to achieve the above-mentioned object, the organic light emitting diode display according to the present invention is configured to change the waveform of the free voltage VRPRE.

For example, when the black data voltage is being widened, the present invention polls and rises the all-precharge voltage VRPRE.

Accordingly, an overlap capacitance due to the overlap of the data line DL and the sensing line SL is not generated. Therefore, the kickback phenomenon due to the overlap capacitance can be prevented or minimized.

Third, according to the present invention, the following effects can be expected.

By changing the waveform of the all-one voltage VRPRE, the overlap capacitance between the data line DL and the sensing line SL is not generated, and thereby, the kickback phenomenon due to the overlap capacitance can be prevented or minimized have. Therefore, the phenomenon that the first nodes included in the subpixels of the first horizontal line are shaken by the kickback phenomenon can be prevented or minimized. Thus, the luminance of the sub-pixels of the first horizontal line can be prevented from being reduced.

The organic light emitting display according to the present invention includes subpixels 110 defined by gate lines GL1 to GLg and data lines DL1 to DLd as shown in FIGS. A data driver 300 for supplying data voltages Vdata to the data lines DL1 to DLd, a gate driver 200 for supplying gate pulses to the gate lines GL1 to GLg, A controller 400 for controlling the data driver 300 and the gate driver 200, and a sensing unit for performing sensing for external compensation on the subpixels and collecting sensing data. The sensing unit may be included in the data driver 300 or independently of the data driver 300. Hereinafter, an organic light emitting display device in which the sensing unit is provided in the data driver 300 will be described as an example of the present invention.

4, the panel 100 defines a region in which the subpixels 110 and the subpixels 110 are formed and outputs a signal for supplying a driving signal to the pixel driving circuit PDC, Lines DL, GL, PLA, PLB, SL and SPL are formed.

A data voltage is supplied to the data line DL, a gate pulse is supplied to the gate line GL, a first driving power source EVDD is supplied to the first driving power line PLA, The second driving power source EVSS is supplied to the first driving power line PLB and the alkaline voltage VRPRE is supplied to the sensing line SL and the sensing transistor SPL is connected to the sensing pulse line SPL. Tsw2) is turned on or off.

At least three of the sub-pixels 110 form one unit pixel 120. In the following description, four subpixels 110 (red subpixel R, white subpixel W, green subpixel G and blue subpixel B), as shown in FIG. 3, The present invention will be described by way of an example in which one unit pixel 120 is formed. Particularly, FIG. 3 shows two unit pixels 120 composed of a red subpixel R, a white subpixel W, a green subpixel G and a blue subpixel B.

In this case, one sensing line (SL) may be commonly connected to the unit pixel (120). Therefore, when d data lines DL1 to DLd are formed on the horizontal line of the panel 100, the number k of the sensing lines SL is d / 4. However, the sensing line may be provided for each sub-pixel.

Each of the plurality of subpixels 110 may include a pixel driving circuit PDC and an organic light emitting diode (OLED) as shown in FIG.

For example, each of the sub-pixels 110 includes a switching transistor Tsw1 connected to a gate line GL and a data line DL, an organic light emitting diode OLED outputting light, a switching transistor Tsw1, And a driving transistor Tdr and a sensing transistor Tsw2 for controlling the magnitude of a current output to the organic light emitting diode according to a data voltage Vdata transmitted through the organic light emitting diode. The sensing transistor Tsw2 is connected to the first node n1 and the sensing line SL between the driving transistor Tdr and the organic light emitting diode OLED and is turned on or off by the sensing pulse SP. And senses the characteristics of the driving transistor during a sensing period during a blank period. The second node n2 connected to the gate of the driving transistor is connected to the switching transistor Tsw1. A storage capacitance Cst is formed between the second node n2 and the first node n1. Components other than the organic light emitting diode (OLED) form the pixel driving circuit (PDC).

In the above description, the structure of the subpixel 110 for performing external compensation has been described with reference to FIG. 4. However, the subpixel 110 may be formed in various structures in addition to the structure shown in FIG. 4 . The specific structure of the subpixel for performing external compensation and the specific method of external compensation are beyond the scope of the present invention. Thus, an example of a subpixel for external compensation and an external compensation method are briefly described or omitted with reference to FIGS. 3 and 4. FIG.

For example, an object of the present invention is to prevent luminance reduction of a first horizontal line due to a kickback phenomenon in an organic light emitting display device performing external compensation. Thus, the structure of the subpixel for external compensation and the method of performing external compensation can be selected from the various subpixel structures and various external compensation methods currently proposed for external compensation. For example, the structure of the subpixel for external compensation and the method of performing external compensation can be applied to structures and methods disclosed in a number of patents, including Japanese Laid-Open Patent Application No. 10-2013-0066449 And the invention disclosed in Application No. 10-2013-0150057 and Application No. 10-2013-0149213 filed by the present applicant may also be applied.

Second, the gate driver 200 sequentially generates gate pulses in response to a gate control signal GCS supplied from the controller 400 and sequentially supplies gate pulses to the gate lines GL1 to GLg. The gate driver 200 may be formed directly on the panel 100 together with the thin film transistor forming process of each sub pixel 110 or may be formed in an integrated circuit (IC) form and mounted on the panel. The type in which the gate driver 200 is directly formed on the panel 100 is called a gate in panel (GIP) type.

The controller 400 controls the driving of the gate driver 200 based on the timing synchronization signal TSS input from the external system and the gate control signal GCS for controlling the driving of the data driver 300 And a data control signal DCS for controlling the data control signal DCS. The specific configuration and functions of the controller 400 will be described in detail with reference to FIG.

Fourth, the data driver 300 is connected to the data lines DL1 to DLd and the sensing lines SL. The data driver 300 may supply the free voltage VRPRE to the sensing line during an initialization period that is issued after the sensing period during the blank period and may be shorter than a period during which the free voltage VRPRE is supplied And supplies the black data voltage to the data lines (DL) during a period of time. In addition, the data driver 300 performs a function of varying the free voltage VRPRE according to the black data voltage. The specific configuration and function of the data driver 300 will be described in detail with reference to FIG.

Fifth, the sensing unit performs sensing for external compensation for the subpixels, and collects sensing data. The sensing unit will be described with reference to Fig.

5 is a view illustrating an exemplary configuration of a control unit applied to the organic light emitting diode display according to the present invention.

The controller 400 transmits the sensing image data to be supplied to the pixels formed in the horizontal line on which the external compensation is performed to the data driver 300. The sensing for the external compensation is performed during the sensing period during the blank period. The controller 400 may calculate the external compensation value based on the sensing data Sdata provided from the sensing unit included in the data driver 300 in the sensing period in which the sensing is performed, In the storage unit 450.

5, the controller 400 uses the timing synchronization signal (TSS) transmitted from the external system to input the input image data ID (ID) transmitted from the external system, A data alignment unit 430 for rearranging the plurality of compensated image data Data by using the external compensation value and supplying the reordering compensated image data Data to the data driver 300, A control signal generator 420 for generating the data control signal DCS and the power control signal PCS and a control signal generator 420 for generating the sensing data Sdata transmitted from the sensing unit included in the data driver 300, A calculation unit 410 for calculating the external compensation value for compensating for a characteristic change of the driving transistor formed in each of the pixels, And an output unit 440 for outputting the compensated image data and various control signals DCS and GCS to the data driver 300 or the gate driver 200. [ ). The calculating unit 410 may be formed in the controller 400 or independently of the controller 400. Hereinafter, an OLED display according to the present invention will be described with reference to an example in which the calculating unit 410 is included in the controller 400 as shown in FIG.

6 is a diagram illustrating a configuration of a data driver applied to an OLED display according to an exemplary embodiment of the present invention. Referring to FIG.

The data driver 300 is connected to the data lines DL1 to DLd and the sensing lines SL1 to SLk. 4, when the data driver 300 includes the data voltage output unit 310 and the sensing unit 320, the data voltage output unit 310 outputs the data voltage DL to the data line DL, And the sensing unit 320 is connected to the sensing lines SL.

The data voltage output unit 310 changes the compensated image data to the data voltage Vdata and outputs the data voltage to the data line.

The data driver 300, in particular, the sensing unit 320 supplies the free voltage VRPRE to the sensing line SL during an initialization period occurring after the sensing period during the blank period, And supplies the black data voltage to the data lines DL1 to DLd for a period shorter than the period in which the all-one voltage VRPRE is supplied. In addition, the data driver 300, particularly, the sensing unit 320 varies the alkaline voltage VRPRE according to the black data voltage. In this case, the sensing unit 320 may vary the free voltage VRPRE according to the data control signal DCS transmitted from the controller 400.

7 is a diagram illustrating waveforms of signals applied to the organic light emitting diode display according to the present invention. Hereinafter, a driving method of an OLED display according to the present invention will be described with reference to FIGS. 2 to 7. FIG.

One frame period includes a display period in which an image is output through the panel 100 and a blank period in which no image is output.

The blank period includes a sensing period in which a threshold voltage or mobility of the driving transistor Tdr is sensed, and an initialization period (Initial) formed between the sensing period and the display period.

First, during the display period, gate pulses are sequentially supplied to the gate lines GL1 to Glg, and data voltages corresponding to one horizontal line are output to the data lines DL1 to DLd. Accordingly, an image is output to the panel during the display period.

In this case, the free voltage VRPRE having a high level can be output to the sensing line SL. Accordingly, the voltage Vn1 of the first node may be changed to various values.

Second, when the sensing period arrives during the blank period, sensing is performed on the driving transistors Tdr provided on any one of the horizontal lines forming the panel. In this case, the mobility or the threshold voltage of the driving transistors Tdr may be sensed. As described above, various sensing methods currently used can be applied to the sensing method during the sensing period.

During the sensing period, sensing data voltages may be supplied to the data lines. The alkaline voltage VRPRE having a low level is supplied to the sensing line SL. In this case, the voltage Vn1 of the first node may be 0V.

The controller 400 calculates the external compensation value for each subpixel using the sensing data collected during the sensing period. The control unit 400 converts the input image data into the compensated image data using the calculated external compensation values, and supplies the compensated image data to the data driver 300 during the frame period after the sensing period. Lt; / RTI >

Third, the data driver 300, in particular, the sensing unit 320 supplies the free voltage VRPRE to the sensing line during the initialization period, which is issued after the sensing period during the blank period, And supplies the black data voltage (VBdata) to the data lines for a period shorter than the period in which the pre-voltage is supplied. In this case, the data driver 300, particularly, the sensing unit 320 varies the alkaline voltage according to the black data voltage VBdata.

For example, when the black data voltage (Vdata) is increased, the data driver 300 polls and rises the all-prime voltage like the area indicated by X1 in FIG.

Accordingly, as shown in FIG. 7, in the initialization period, the voltage Vn1 of the first node is not instantaneously increased by the kickback phenomenon, but is kept constant.

Fourth, after the black data voltage VBdata is polled, the controller 400 controls the data driver 300 and the gate driver 200 to output an image to the panel 100. That is, after the black data voltage VBdata is polled, the display period of another frame period starts.

When the black data voltage is polled, the data driver 300 may poll the free voltage VRPRE after polling as shown by X2 in FIG. By this operation, the voltage (Vn1) of the first node can be further stabilized, and the influence between the initialization period and the display period can be reduced.

By changing the waveform of the all-one voltage VRPRE, the overlap capacitance between the data line DL and the sensing line SL is not generated, and thereby, the kickback phenomenon due to the overlap capacitance can be prevented or minimized have. Therefore, the phenomenon that the first nodes included in the subpixels of the first horizontal line are shaken by the kickback phenomenon can be prevented or minimized. Thus, the luminance of the sub-pixels of the first horizontal line can be prevented from being reduced.

It will be understood by those skilled in the art that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: panel 200: gate driver
300: Data driver 400: Timing controller
110: subpixel 120: unit pixel
410: Calculator 420: Control signal generator
430: Data sorting unit 440: Output unit
450: storage unit 310: data voltage output unit
320: sensing unit

Claims (6)

A panel having subpixels defined by gate lines and data lines; A data driver for supplying data voltages to the data lines; A gate driver for supplying gate pulses to the gate lines; And a control unit for controlling the data driver and the gate driver,
Each of the subpixels includes: a switching transistor connected to a gate line and a data line; An organic light emitting diode for outputting light; A driving transistor for controlling a magnitude of a current output to the organic light emitting diode according to a data voltage transmitted through the switching transistor; And a sensing transistor connected to a first node between the driving transistor and the organic light emitting diode and a sensing line, the sensing transistor being turned on or off by a sensing pulse and sensing a characteristic of the driving transistor during a sensing period during a blank period and,
Wherein the data driver supplies the free voltage to the sensing line during an initialization period which is issued after the sensing period during the blank period and supplies the black data voltage to the data lines for a period shorter than the period during which the free voltage is supplied Supply,
Wherein the data driver varies the free voltage according to the black data voltage. The method according to claim 1,
The data driver includes:
And polling and rising the alkaline voltage when the black data voltage is increased. 3. The method of claim 2,
The data driver includes:
And when the black data voltage is polled, polling and raising the all-free voltage. The method according to claim 1,
And the voltage of the first node is kept constant. The method according to claim 1,
And the control unit controls the data driver and the gate driver to output an image to the panel after the black data voltage is polled. The method according to claim 1,
Wherein,
The method includes calculating an external compensation value for each subpixel using the sensing data collected during the sensing period, converting the input image data into compensated image data using the calculated external compensation values, The organic light emitting display device according to claim 1,

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