KR100812058B1 - Organic light emitting display - Google Patents

Abstract

An organic light emitting display is provided to improve reliability of the display by electrically determining failures of pixels with accuracy. An organic light emitting display includes a scan driving unit, a data driving unit, and pixels. The scan driving unit sequentially supplies scanning signals to first scanning lines in a normal driving state, supplies the scanning signals to the first scanning lines in an inspection process, and supplies inspection signals to second scanning lines. The data driving unit includes an amplifier block. The amplifier block includes a sense amplifier(123i). The sense amplifier includes a tenth transistor(M10), an eleventh transistor(M11), a thirteenth transistor(M13), and a twelfth transistor(M12). The thirteenth transistor is connected between second electrodes of the eleventh transistor and the fourteenth transistor. First electrodes of the tenth transistor and the eleventh transistor are connected to third power(VDD).

Description

Organic Light Emitting Display

1 is a circuit diagram showing a conventional pixel.

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

3 is a diagram illustrating an example embodiment of a pixel illustrated in FIG. 2.

FIG. 4A is a waveform diagram illustrating a driving waveform supplied when the pixel illustrated in FIG. 3 is normally driven.

FIG. 4B is a waveform diagram illustrating driving waveforms supplied during the inspection process of the pixel illustrated in FIG. 3.

5 is a diagram illustrating a configuration included in the data driver to check whether a pixel is abnormal.

6 is a circuit diagram showing a connection between a data line and a sense amplifier.

<Explanation of symbols for the main parts of the drawings>

2,142: pixel circuit 4,140: pixel

110: scan driver 120: data driver

122: decoder 124: reference voltage generator

125: control unit 128: selection block

129: amplifier block 130: pixel portion

150: timing controller 1211, 1212, 121j: selection unit

1231,1232,123i: Sense Amplifier

The present invention relates to an organic light emitting display device, and more particularly, to an organic light emitting display device capable of improving reliability.

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

Among flat panel displays, an organic light emitting display device displays an image using an organic light emitting diode that generates light by recombination of electrons and holes. Such an organic light emitting display device has an advantage of having a fast response speed and being driven with low power consumption.

1 is a circuit diagram illustrating a pixel of a conventional organic light emitting display device.

Referring to FIG. 1, a pixel 4 of a conventional organic light emitting display device is connected to an organic light emitting diode OLED, a data line Dm, and a scanning line Sn to control the organic light emitting diode OLED. The pixel circuit 2 is provided.

The anode electrode of the organic light emitting diode OLED is connected to the pixel circuit 2, and the cathode electrode is connected to the second power source ELVSS. Such an organic light emitting diode (OLED) generates light having a predetermined brightness in response to a current supplied from the pixel circuit 2.

The pixel circuit 2 controls the amount of current supplied to the organic light emitting diode OLED corresponding to the data signal supplied to the data line Dm when the scan signal is supplied to the scan line Sn. To this end, the pixel circuit 2 includes a second transistor M2 connected between the first power supply ELVDD and the organic light emitting diode OLED, the second transistor M2, the data line Dm, and the scan line Sn. And a first capacitor M1 connected between the first transistor M1 and a storage capacitor Cst connected between the gate electrode and the first electrode of the second transistor M2.

The gate electrode of the first transistor M1 is connected to the scan line Sn, and the first electrode is connected to the data line Dm. The second electrode of the first transistor M1 is connected to one terminal of the storage capacitor Cst. Here, the first electrode is set to any one of a source electrode and a drain electrode, and the second electrode is set to an electrode different from the first electrode. For example, when the first electrode is set as the source electrode, the second electrode is set as the drain electrode. The first transistor M1 connected to the scan line Sn and the data line Dm is turned on when a scan signal is supplied from the scan line Sn to receive a data signal supplied from the data line Dm to the storage capacitor Cst. ). In this case, the storage capacitor Cst charges a voltage corresponding to the data signal.

The gate electrode of the second transistor M2 is connected to one terminal of the storage capacitor Cst, and the first electrode is connected to the other terminal of the storage capacitor Cst and the first power supply ELVDD. The second electrode of the second transistor M2 is connected to the anode electrode of the organic light emitting diode OLED. The second transistor M2 controls the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the organic light emitting diode OLED in response to the voltage value stored in the storage capacitor Cst. In this case, the organic light emitting diode OLED generates light corresponding to the amount of current supplied from the second transistor M2.

In fact, the conventional pixel illustrated in FIG. 1 displays a predetermined image while repeating a process of charging a voltage corresponding to a data signal to a storage capacitor Cst and generating light of luminance corresponding to the charged voltage. . However, such a conventional organic light emitting display device has a problem in that an image of a desired luminance cannot be displayed due to a process variation.

In detail, the organic light emitting display device is currently formed through various processes (eg, LTPS). Here, a problem occurs such that a voltage applied to the anode electrode of the organic light emitting display device is changed due to the deviation of the process. In order to prevent this, conventionally, in the inspection process, the quality of the image is checked by a human eye to identify a good or defective product. However, such a test has a problem in that it does not secure reliability because it depends on the subjective judgment of the inspector.

Accordingly, an object of the present invention is to provide an organic light emitting display device capable of improving reliability.

In order to achieve the above object, the organic light emitting display device according to an exemplary embodiment of the present invention sequentially supplies the scan signal to the first scan lines during the normal driving, and supplies the scan signal to the first scan lines during the inspection process. A scan driver for supplying a test signal to the second scan lines; A data driver for supplying a test data signal to the data lines during the test process and a data signal to the data lines during the normal driving; Pixels positioned at each intersection of the first scan lines, the second scan lines, and the data lines, and supplying a voltage applied to the organic light emitting diode included in each of the test lines when the test signal is supplied to the data lines. To; The data driver determines whether the pixels are abnormal in response to the voltage supplied to the data lines during the inspection process.

Preferably, the scan signal is supplied to the k-th second scan line after the scan signal is supplied to the k-th first scan line during the inspection process period. A first transistor connected to each of the first scan line and the data line and turned on when the scan signal is supplied; A storage capacitor configured to charge a voltage corresponding to the data signal or the test data signal when the first transistor is turned on; A second transistor for supplying a current corresponding to the voltage charged in the storage capacitor to the organic light emitting diode; And a third transistor connected between the anode electrode of the organic light emitting diode and the data line and turned on when the test signal is supplied. The voltage applied to the organic light emitting diode is a voltage applied when a current is supplied from the second transistor to the organic light emitting diode in response to the inspection data signal. The data driver includes a plurality of selectors respectively connected to i (i is a natural number) data lines, a decoder for selecting any one of the plurality of selectors, and data connected to a selector selected by the decoder. Determining whether the pixels are abnormal according to i sense amplifiers electrically connected to any one of the lines, a reference voltage generator for supplying a reference voltage to the sense amplifiers, and an output result of the sense amplifiers It has a control unit for. The sense amplifiers compare the voltage applied to the organic light emitting diode supplied from the data line connected with the voltage value of the reference voltage, and supply a high or low voltage to the controller in response to the comparison result.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 6 that can be easily implemented by those skilled in the art.

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

2, an organic light emitting display device according to an embodiment of the present invention is positioned to be connected to first scan lines S11 to S1n, second scan lines S21 to S2n, and data lines D1 to Dm. The pixel unit 130 including the pixels 140, the scan driver 110 for driving the first scan lines S11 to S1n and the second scan lines S21 to S2n, and the data lines D1. To Dm), and a timing controller 150 for controlling the scan driver 110 and the data driver 120.

The scan driver 110 receives the scan driving control signal SCS from the timing controller 150. During normal driving, the scan driver 110 generates a scan signal and sequentially supplies the generated scan signal to the first scan lines S11 to S1n. In addition, the scan driver 110 generates a scan signal and an inspection signal during an initial inspection process for inspecting the pixel unit 130. The scan signal is sequentially supplied to the first scan lines S11 to S1n, and the scan signal is sequentially supplied to the second scan lines S21 to S22. Here, the inspection signal is supplied during the initial inspection process period, and is not supplied when the pixel unit 130 is normally driven.

The data driver 120 receives the data drive control signal DCS from the timing controller 150. During normal driving, the data driver 120 generates a data signal corresponding to the data and supplies the generated data signal to the data lines D1 to Dm in synchronization with the scan signal. In addition, during the inspection process period, the data driver 120 generates an inspection data signal and supplies the generated inspection data signal to the data lines D1 to Dm to be synchronized with the inspection signal. Here, the data driver 120 determines whether the pixels 140 are defective by using voltages applied to the data lines D1 to Dm during the inspection process period.

The test data signal may be set to various voltage values by an operator as a signal for checking whether the pixels 140 are abnormal. In addition, the inspection data signal may be supplied differently to each of the red, green, and blue pixels, or may be equally supplied to all the pixels 140.

The timing controller 150 generates a data drive control signal DCS and a scan drive control signal SCS in response to external synchronization signals. The data driving control signal DCS generated by the timing controller 150 is supplied to the data driver 120, and the scan driving control signal SCS is supplied to the scan driver 110. The timing controller 150 supplies the data Data supplied from the outside to the data driver 120.

The pixel unit 130 receives the first power source ELVDD and the second power source ELVSS from the outside and supplies the same to the pixels 140. Each of the pixels 140 supplied with the first power source ELVDD and the second power source ELVSS generates light corresponding to the data signal or the test data signal. Here, the first power supply ELVDD is set to a higher voltage value than the second power supply ELVSS.

3 is a circuit diagram illustrating a pixel according to an exemplary embodiment of the present invention. In FIG. 3, for convenience of description, the pixel connected to the first n th scan line S1n and the m th data line Dm will be illustrated.

Referring to FIG. 3, the pixel 140 according to the exemplary embodiment of the present invention is connected to the organic light emitting diode OLED, the data line Dm, the first scan line S1n, and the second scan line S2n. The pixel circuit 142 for controlling the diode OLED is provided.

The anode electrode of the organic light emitting diode OLED is connected to the pixel circuit 142, and the cathode electrode is connected to the second power source ELVSS. Such an organic light emitting diode (OLED) generates light having a predetermined luminance in response to a current supplied from the pixel circuit 142.

The pixel circuit 142 controls the amount of current supplied to the OLED in response to the data signal or the inspection data signal. The pixel circuit 142 transfers the voltage applied to the anode electrode of the organic light emitting diode OLED to the data line Dm when a current corresponding to the test data signal is supplied to the organic light emitting diode OLED. To this end, the recovery circuit 142 includes first to third transistors M1 to M3 and a storage capacitor Cst.

The gate electrode of the first transistor M1 is connected to the first scan line S1n, and the first electrode is connected to the data line Dm. The second electrode of the first transistor M1 is connected to the gate electrode of the second transistor M2 (driving transistor). The first transistor M1 supplies a data signal or a test data signal supplied to the data line Dm to the gate electrode of the second transistor M2 when the scan signal is supplied to the first scan line S1n.

The gate electrode of the second transistor M2 is connected to the second electrode of the first transistor M1, and the first electrode is connected to the first power source ELVDD. The second electrode of the second transistor M2 is connected to the anode electrode of the organic light emitting diode OLED. The second transistor M2 controls the amount of current flowing from the first power source ELVDD to the second power source ELVSS via the organic light emitting diode OLED in response to the voltage applied to its gate electrode.

The gate electrode of the third transistor M3 is connected to the second scan line S2n, and the first electrode is connected to the anode electrode of the organic light emitting diode OLED. The second electrode of the third transistor M3 is connected to the data line Dm. When the test signal is supplied to the second scan line Sn, the third transistor M3 is turned on to transfer a voltage applied to the organic light emitting diode OLED to the data line Dm.

One terminal of the storage capacitor Cst is connected to the gate electrode of the second transistor M2, and the other terminal of the storage capacitor Cst is connected to the first power source ELVDD. The storage capacitor Cst charges a voltage corresponding to the data signal or the test data signal when the first transistor M1 is turned on.

4A is a diagram showing a drive waveform supplied when a pixel is normally driven.

Referring to FIGS. 3 and 4A, an operation process will be described. First, a scan signal is supplied to the first scan line S1n when the pixel is normally driven. When the scan signal is supplied to the first scan line S1n, the first transistor M1 is turned on and the data signal DS supplied to the data line Dm is supplied to the gate electrode of the second transistor M2.

In this case, the storage capacitor Cst charges a voltage corresponding to the difference between the voltage of the data signal DS and the first power source ELVDD. Thereafter, the supply of the scan signal to the first scan line S1n is stopped and the first transistor M1 is turned off. Then, the second transistor M2 supplies the current corresponding to the voltage charged in the storage capacitor Cst to the organic light emitting diode OLED to generate light having the luminance corresponding to the data signal. In fact, the pixels 140 of the present invention display the image having a predetermined luminance in the pixel unit 130 while repeating the above-described process during normal driving.

4B is a view showing driving waveforms supplied during an inspection process.

Referring to FIGS. 3 and 4B, the operation process will be described. First, a scan signal is supplied to the first scan line S1n during the inspection process period. When the scan signal is supplied to the first scan line S1n, the first transistor M1 is turned on and the test data signal EDS supplied to the data line Dm is supplied to the gate electrode of the second transistor M2. .

In this case, the storage capacitor Cst charges a voltage corresponding to the difference between the voltage of the test data signal EDS and the first power supply ELVDD. Thereafter, the supply of the scan signal to the first scan line S1n is stopped, and the test signal is supplied to the second scan line S2n. When the test signal is supplied to the second scan line S2n, the third transistor M3 is turned on.

When the third transistor M3 is turned on, the voltage applied to the organic light emitting diode OLED corresponds to a current supplied from the second transistor M2 (that is, a current corresponding to the test data signal). Is supplied. The voltage supplied to the data line Dm is supplied to the data driver 120, and the data driver 120 checks whether the pixel 140 is abnormal using the voltage supplied to the data line Dm. Indeed, the pixel 140 of the present invention is determined whether or not defective through this inspection process.

To this end, the scan driver supplies the scan signal to the k-th second scan line S2k after the scan signal is supplied to the k-th first scan line S1k during the inspection process period.

5 is a block diagram illustrating a configuration included in a data driver to determine whether a pixel is defective.

Referring to FIG. 5, the data driver 120 of the present invention includes a selection block 128, a decoder 122, an amplifier block 129, a reference voltage generator 124, and a controller 125.

The selection block 128 includes a plurality of selection parts 1211 to 121j. Each of the selectors 1211 to 121j is connected to i data lines D (i is a natural number).

The decoder 122 selects any one of the selection units 1211 to 121j included in the selection block 128. For example, the decoder 1211 may sequentially select the first selector 1211 to the j th selector 121j.

The amplifier block 129 includes a plurality of sense amplifiers 1231 to 123i. In practice, the amplifier block 129 includes i sense amplifiers 1231 to 123i. Each of the sense amplifiers 1231 to 123i receives a predetermined voltage from the selector 1211 to 121j selected by the decoder 1211.

For example, when the first selector 1211 is selected, the first sense amplifier 1231 receives a voltage from the first data line D1, and the second sense amplifier 1232 receives the second data line ( The voltage from D2) is supplied. The i-th sense amplifier 123i receives the voltage from the i-th data line Di. That is, each of the sense amplifiers 1231 to 123i receives a predetermined voltage from any one of the data lines D connected to the selection units 1211 to 121j selected by the decoder 122.

The reference voltage generator 124 supplies a predetermined reference voltage ref to each of the sense amplifiers 1231 to 123i. Here, the reference voltage ref is experimentally determined to determine whether the pixels 140 are defective. The reference voltage generator 124 may supply different reference voltages ref to correspond to the red pixel, the green pixel, and the blue pixel. For example, a sense amplifier receives a voltage from a data line D connected to a red pixel, and a sense amplifier receives a voltage from a data line D connected to a green pixel. ref) can be supplied. Each of the sense amplifiers 1231 to 123i compares the voltage supplied from the data line D with the reference voltage Vref, and supplies the comparison result to the controller 125.

The controller 125 determines whether the pixels 140 are abnormal in response to a comparison result supplied from the sense amplifiers 1231 to 123i.

6 is a circuit diagram showing when the data line and the sense amplifier are connected. In FIG. 6, the pixel connected to the m-th data line Dm and the 1n-th scan line S1n is illustrated, and the i-th sense amplifier 123i is illustrated.

Referring to FIG. 6, the sense amplifier 123i may include the tenth transistor M10 and the eleventh transistor M11, the second transistor M11 and the fourteenth transistor M14, which are connected to each other in the form of current mirrors. A thirteenth transistor M13 connected between the electrodes, and a twelfth transistor M12 connected between the tenth transistor M10 and the second electrode of the fourteenth transistor are provided.

The first electrodes of the tenth transistor M10 and the eleventh transistor M11 are connected to the third power source VDD. The gate electrode and the second electrode of the tenth transistor M10 are electrically connected to each other.

The gate electrode of the twelfth transistor M12 is electrically connected to the data line Dm to receive a voltage applied to the organic light emitting diode OLED from the data line Dm. The gate electrode of the thirteenth transistor M13 is supplied with the reference voltage Ref.

The first electrode of the fourteenth transistor M14 is connected to the fourth power source VSS. The fourteenth transistor M14 is turned on by the enable signal EN.

The sense amplifier 123i supplies a low or high voltage to the controller 125 in response to a result of comparing the voltage input to the gate electrode of the twelfth transistor M12 with the reference voltage Ref. In detail, when the voltage of the organic light emitting diode OLED input to the gate electrode of the twelfth transistor M12 is lower than the voltage of the reference voltage Ref, the voltage of the low L is supplied to the controller 125. In other cases, a high voltage is supplied. Such a sense amplifier 123i is currently used in various general applications.

4B and 6, the scan signal is first supplied to the first scan line S1n, and the storage capacitor Cst is charged with a voltage corresponding to the test data signal. Thereafter, the scan signal is supplied to the second scan line S2n to turn on the third transistor M3.

Then, the voltage applied to the organic light emitting diode OLED is supplied to the sense amplifier 123i in response to the current supplied from the second transistor M2 in response to the voltage charged in the storage capacitor Cst. In this case, the sense amplifier 123i compares the voltage applied to the organic light emitting diode OLED with the reference voltage Ref and supplies a voltage corresponding to the comparison result to the controller 125. At this time, the controller 125 determines whether the pixel 140 is normal in response to the comparison result.

For example, the controller 125 may determine that the pixels 140 are in normal operation when the high H signal is input, and determine that the pixels 140 are abnormal when the low L signal is input. Can be. In this case, the controller 125 controls the reference voltage generator 124 to find the reference voltage Ref to which the high H signal is input while lowering the reference voltage Ref. Then, whether the pixel 140 is used is determined using the voltage value of the reference voltage Ref to which the high H signal is input.

For example, the pixel 140 may be determined to be defective if the reference voltage Ref is lowered below the voltage applied to the anode electrode of the OLED when expressing white luminance. In fact, in the present invention, it is possible to determine whether the pixels 140 are defective while changing the voltage of the reference voltage Ref in various forms.

The above detailed description and drawings are merely exemplary of the present invention, but are used only for the purpose of illustrating the present invention and are not intended to limit the scope of the present invention as defined in the meaning or claims. Accordingly, those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical protection scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

As described above, the organic light emitting display device according to the embodiment of the present invention determines whether the pixels are defective by using a voltage applied to the organic light emitting diode during the initial inspection process. Therefore, it is possible to accurately determine whether or not the pixels are electrically defective, thereby ensuring reliability.

Claims (6)

A scan driver for sequentially supplying scan signals to the first scan lines during normal driving, supplying the scan signals to the first scan lines during the inspection process, and supplying the scan signals to the second scan lines; A data driver for supplying a test data signal to the data lines during the test process and a data signal to the data lines during the normal driving; Pixels positioned at each intersection of the first scan lines, the second scan lines, and the data lines, and supplying a voltage applied to the organic light emitting diode included in each of the test lines when the test signal is supplied to the data lines. To; And the data driver detects whether the pixels are abnormal in response to the voltage supplied to the data lines during the inspection process. The method of claim 1, And the test signal is supplied to the k-th second scan line after the scan signal is supplied to the k-th first scan line during the inspection process period. The method of claim 2, Each of the pixels A first transistor connected to the first scan line and the data line and turned on when the scan signal is supplied; A storage capacitor configured to charge a voltage corresponding to the data signal or the test data signal when the first transistor is turned on; A second transistor for supplying a current corresponding to the voltage charged in the storage capacitor to the organic light emitting diode; And a third transistor connected between the anode electrode of the organic light emitting diode and the data line, the third transistor being turned on when the test signal is supplied to the organic light emitting display device. The method of claim 3, wherein And the voltage applied to the organic light emitting diode is a voltage applied when a current is supplied from the second transistor to the organic light emitting diode in response to the inspection data signal. The method of claim 4, wherein The data driver a plurality of selectors respectively connected to i (i is a natural number) data lines, A decoder for selecting any one of the plurality of selection units; I sense amplifiers electrically connected to any one of the data lines connected to the selector selected by the decoder; A reference voltage generator for supplying a reference voltage to the sense amplifiers; And a controller configured to determine whether the pixels are abnormal in response to an output result of the sense amplifiers. The method of claim 5, The sense amplifiers compare the voltage applied to the organic light emitting diode supplied from the data line connected with the voltage value of the reference voltage, and supply a high or low voltage to the controller in response to the comparison result. An organic light emitting display device.

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