KR101238008B1 - Light Emitting Device, Light Emitting Display equipping the same and method for driving thereof - Google Patents

Abstract

The present invention provides a display panel including a pixel portion including a plurality of pixel circuits formed in an area where a plurality of data lines and a plurality of scan lines intersect, and a dummy pixel portion including a plurality of dummy pixel circuits, and a plurality of scan lines. Scan driver for sequentially applying scan signals to the plurality of pixel circuits and dummy pixel circuits, a data driver for transferring data signals to the plurality of data lines, and a current for measuring a current flowing in the dummy pixel portion The present invention provides an electroluminescence display device including a current detector and a data corrector for correcting a data signal according to the amount of current measured by the current detector.

Description

Light Emitting Device, Light Emitting Display equipping the same and method for driving

1 is a pixel circuit diagram of a general electroluminescent display.

2 is a block diagram illustrating an electroluminescent display device according to an exemplary embodiment of the present invention.

3 is a circuit diagram illustrating a pixel circuit of a pixel unit and a dummy pixel circuit of a dummy pixel unit of an electroluminescent display according to an exemplary embodiment of the present invention.

4 is a block diagram illustrating a data correction unit of an electroluminescent display device according to an exemplary embodiment of the present invention.

5 is a block diagram illustrating a display panel of an electroluminescent display device according to an exemplary embodiment of the present invention.

The present invention relates to an electroluminescent display and a driving method thereof.

2. Description of the Related Art In recent years, the importance of flat panel displays (FPDs) has been increasing with the development of multimedia. In response, various types of liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), light emitting device (light emitting device), etc. Flat panel displays have been put to practical use.

In particular, the organic light emitting display device has a high response time with a response speed of 1 ms or less, low power consumption, and self-emission. In addition, there is no problem in viewing angle, which is advantageous as a moving image display medium regardless of the size of the device. In addition, low-temperature manufacturing is possible, and the manufacturing process is simple based on the existing semiconductor process technology has attracted attention as a next-generation flat panel display device in the future.

In general, an organic light emitting display device is a display device that electrically excites fluorescent organic compounds and emits light, and performs voltage driving or current driving of N × M organic light emitting diodes (OLEDs) arranged in a matrix form. Programming to express an image. The organic light emitting display device may be driven by a passive matrix method and an active matrix method using a thin film transistor. The passive matrix method forms the anode and the cathode so as to be orthogonal and selects and drives the line, whereas the active matrix method connects the thin film transistor to each indium tin oxide (ITO) pixel electrode and is connected by a capacitor capacitance connected to the gate electrode of the thin film transistor. Drive according to the maintained voltage.

2 is a circuit diagram illustrating a pixel circuit of an organic light emitting display device.

Referring to FIG. 2, the pixel circuit receives data through a switching transistor MS and a switching transistor MS which transmit a data signal from the data line Dm in response to a selection signal from the scan line Sn. A capacitor Cgs for storing a signal, a driving transistor MD for generating a driving current according to a data signal stored in the capacitor Cgs, and an organic light emitting diode OLED for performing a light emitting operation according to the driving current do.

The amount of current flowing through the organic light emitting diode OLED can be expressed as follows.

In the active matrix type organic light emitting display device including the pixel circuit as described above, the luminance is adjusted as the amount of current flowing through the organic light emitting diode OLED. Therefore, the uniformity of the thin film transistor, in particular, the uniformity of the threshold voltage Vth and mobility must be ensured.

The thin film transistor used in the organic light emitting display device may be formed using amorphous silicon or low temperature polycrystalline silicon. The polycrystalline silicon has a field effect mobility of about 100 to 200 times greater than that of the amorphous silicon, and thus the thin film transistor using the polycrystalline silicon. The need for this is increasing.

Polycrystalline silicon can be manufactured by crystallizing amorphous silicon using an excimer laser annealing method, etc. Since the excimer laser has a narrow pulse width during the crystallization process, the excimer laser is repeatedly irradiated several times. It will crystallize amorphous silicon. At this time, since the pulse of the excimer laser is uneven, the grain size is uneven for each region. Therefore, the characteristics are different between the thin film transistors including the polycrystalline silicon semiconductor layer formed in each pixel, so that uniformity may not be secured, thereby causing variation in luminance between the pixels.

In addition, the characteristics of the semiconductor layer made of the polycrystalline silicon layer may be degraded due to electrical stress as the display device is used. Therefore, since the threshold voltage continuously changes over time, it is not possible to express the desired luminance by applying the same data voltage, thereby degrading the quality of the video image.

Accordingly, an object of the present invention is to provide an electroluminescent display device and a driving method thereof capable of improving the quality of a screen.

In order to achieve the above technical problem, the present invention includes a pixel portion including a plurality of pixel circuits formed in an area where a plurality of data lines and a plurality of scan lines intersect, and a dummy pixel portion including a plurality of dummy pixel circuits. A display panel configured to sequentially apply scan signals to a plurality of scan lines, a scan driver to select a plurality of pixel circuits and dummy pixel circuits, a data driver to transfer data signals to the plurality of data lines, and a dummy pixel An electroluminescent display device includes a current sensing unit for measuring a current flowing through a unit, and a data correction unit for correcting a data signal according to the amount of current measured by the current sensing unit.

The pixel circuit includes a first switching transistor that transfers a data signal from the data line in response to a selection signal from the scan line, a first capacitor for storing a data signal received through the first switching transistor, and data stored in the first capacitor. A first driving transistor for generating a driving current according to the signal, and an organic light emitting diode for performing a light emitting operation according to the driving current.

The dummy pixel circuit is stored in a second switching transistor that transfers a data signal from the data line in response to a selection signal from the scan line, a second capacitor for storing a data signal received through the second switching transistor, and a second capacitor. And a second driving transistor for generating a driving current according to the data signal.

The data signal applied to the dummy pixel circuit may be an average value or the mode value of the data signal applied to the pixel circuit in a predetermined region of the pixel portion.

One end of the second driving transistor may be connected to the current sensing unit.

The data correction unit receives a measurement value from the current sensing unit and converts it into a digital signal, a memory unit for storing a reference value of current flowing in the pixel unit, a measured value converted from the digital converter and a reference value stored in the memory unit. A comparator for comparing and a compensator for generating a data compensation signal according to the comparison result of the comparator may be included.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram illustrating an electroluminescent display device according to an exemplary embodiment of the present invention.

2, the electroluminescent display device 100 according to an exemplary embodiment of the present invention may include a display panel 110, a scan driver 120, a data driver 130, a controller 140, and a power supply unit (not shown). ), A current detector 150, and a data corrector 160.

The control unit 140 outputs a control signal to the scan driver 120, the data driver 130, the power supply unit 150, and the like, and the power supply unit 150 includes the scan driver 120, according to the driving control of the controller 140. The voltage required to drive the data driver 130 and the display panel 110 is output.

The scan driver 120 outputs a scan signal to scan lines connected to the scan driver 120 according to a control signal of the controller 140, thereby selecting pixel circuits located in the display panel 110.

The data driver 130 is positioned in the display panel 110 through data lines connected to the data driver 130 in synchronization with the scan signal output from the scan driver 120 according to the control signal of the controller 140. Applied to the pixel circuits. Accordingly, the display panel 110 displays an image image by emitting light from the pixel circuits in response to the data signals.

3 is a circuit diagram illustrating a display panel of an electroluminescent display device according to an exemplary embodiment of the present invention.

2 and 3, the display panel 110 includes a pixel unit 110A in which pixel circuits are located, and a dummy pixel unit 110B for detecting degradation of the pixel circuit.

The first switching transistor MS_1 and the first switching transistor MS_1 which transfer the data signal from the data line Dm in response to the selection signal from the scan line Sn of the pixel circuit 115A positioned in the pixel portion 110A. The first capacitor Cgs_1 for storing the data signal received through the first signal, the first driving transistor MD_1 for generating the driving current according to the data signal stored in the first capacitor Cgs_1, and the light emitting operation according to the driving current. It includes an organic light emitting diode (OLED) for performing.

Then, the dummy pixel unit located in (110B) dummy pixel circuit (115B) has a second switching transistor (MS_2 that carries data signals from the scan lines in response to the selection signal from the (S _D) of data lines (D1-Dm) ), A second capacitor Cgs_2 for storing a data signal received through the second switching transistor MS_2, and a second driving transistor MD_2 for generating a driving current according to the data signal stored in the second capacitor Cgs_2. ) One end O1-Om of the second driving transistor MD_2 is extended to the outside of the display panel 110 and connected to the current sensing unit 150.

The current detector 150 receives a current from one end (O1-Om) of the second driving transistor MD_2 of the dummy pixel unit 110B. The current detector 150 measures the amount of current flowing through each of the dummy pixels 115B and transmits the amount of current to the data corrector 160.

4 is a block diagram illustrating a data correction unit according to an embodiment of the present invention.

2 and 4, the data corrector 160 includes a digital converter 161, a memory 163, a comparator 165, and a corrector 167.

The digital converter 161 may convert the current value received from the current sensor 150 into a voltage and convert the current value into a digital value. The memory unit 163 may store a reference value. In this case, the reference value may be a digital value corresponding to the driving current generated by the driving transistors of the pixel circuits of the pixel unit, that is, the amount of current before the driving transistor deteriorates.

The comparator 165 compares the converted value of the digital converter 161 with the reference value of the memory unit 163, and the correction unit 167 corrects the data signal to be applied to the pixel unit according to the comparison result of the comparator 165. do. Here, the correction unit 167 may include a look-up-table (LUT) to correct the data signal. The corrected data signal is applied to the data driver 130. In this case, the controller 140 applies the corrected data signal when supplying the data signal corrected by the data corrector 160 to the data driver 130. You can control the viewpoint.

5 is a block diagram illustrating a display panel according to an exemplary embodiment of the present invention. Hereinafter, an operation of an electroluminescent display device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 2 to 5.

2 to 5, when the controller 140 outputs a control signal to the scan driver 120 and the data driver 130, the scan driver 120 scans the scan line according to the control signal of the controller 140. S1-Sn, and outputs a scan signal to the pixel unit (110A) and a dummy pixel portion (110B) of a display panel 110 via the _D S).

The data driver 130 displays data signals through data lines D1-Dm connected to the data driver 130 in synchronization with the scan signal output from the scan driver 120 according to a control signal of the controller 140. The pixel 110 is applied to the pixel portion 110A and the dummy pixel portion 110B of the panel 110. The data signal corresponding to each pixel circuit 115A is applied to the pixel portion 110A. An average value or a mode value of a data signal applied to a predetermined region of the pixel portion 110A may be applied to the dummy pixel portion 110B.

Here, referring to FIG. 5, the dummy pixel unit 110 may have a plurality of dummy pixel circuits Pd1-Pdm, and each of the dummy pixel circuits Pd1-Pdm has a predetermined period A11 of the pixel unit 110A. -Anm) can be represented. That is, since the characteristics of the thin film transistors in adjacent regions are similar when forming the thin film transistor, the degree of deterioration of the thin film transistor may also be similar.

For example, "Pd1" of the dummy pixel circuit may represent the "A11-An1" section of the pixel unit 110A. Therefore, the average value or the mode of the data signal in the "A11-An1" section may be applied to the "Pd1" dummy pixel circuit. In addition, by measuring a current value flowing in the “Pd1” dummy pixel circuit and determining the degree of deterioration, data of the pixel circuits in the “A11-An1” section may be compensated.

The pixel unit 110A of the display panel 110 displays an image image by emitting light from the pixel circuits in response to the data signals, and the dummy pixel unit 110B receives current flowing through the dummy pixel circuits. Transfer to the detection unit 150.

The current detector 150 measures the amount of current applied from each of the dummy pixel circuits Pd1-Pdm of the dummy pixel unit 110B and transmits the amount of current to the data driver 160.

The digital converter 161 of the data driver 160 converts the measured value corresponding to the current applied from the dummy pixel unit 110B into a voltage, converts the measured value into a digital value, and transmits the converted value to the comparator 165. The comparator 165 receives the reference value from the setting memory 163, compares the converted measurement value received from the digital converter 161 with the reference value, and transmits the difference to the correction unit 167. Here, the reference value may be a digital value of the amount of current measured before the driving transistor is degraded.

The correction unit 167 generates a compensation signal to be applied to the data driver 130 according to the difference between the converted measured value and the reference value, and transmits the compensation signal to the data driver 130. In this case, the controller 140 may control the correction unit 167 to control a time point at which the compensation signals are applied to the data driver 130.

The data driver 130 may receive compensation signals and apply each compensation signal to pixel circuits positioned in corresponding regions of the pixel unit 110A.

As described above, the electroluminescent display device according to an exemplary embodiment of the present invention includes a dummy pixel part to measure a decrease in driving current according to the deterioration degree of the thin film transistor, thereby reflecting it in the data signal. Thus, the quality of the screen can be improved by reducing the luminance deviation of each pixel circuit.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. You will understand that. Therefore, since the embodiments described above are provided to fully inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

The present invention has the effect of reducing the luminance deviation of each pixel circuit and improving the screen quality of the electroluminescent display.

Claims (8)

A display panel including a pixel portion including a plurality of pixel circuits formed in an area where a plurality of data lines and a plurality of scan lines intersect, and a dummy pixel portion including a plurality of dummy pixel circuits; A scan driver for sequentially applying a scan signal to the plurality of scan lines to select the plurality of pixel circuits and the dummy pixel circuits; A data driver for transmitting a data signal to the plurality of data lines; A current sensing unit for measuring a current flowing in the dummy pixel unit; And Including a data correction unit for correcting the data signal according to the amount of current measured from the current sensing unit, The pixel circuit may include a first switching transistor configured to transfer a data signal from the data line in response to a selection signal from the scan line, a first capacitor for storing the data signal received through the first switching transistor, And a first driving transistor for generating a driving current according to a data signal stored in the first capacitor, and an organic light emitting diode for performing a light emitting operation according to the driving current. delete The method of claim 1, The dummy pixel circuit may include a second switching transistor configured to transfer a data signal from the data line in response to a selection signal from the scan line, a second capacitor for storing the data signal received through the second switching transistor; And a second driving transistor for generating a driving current according to the data signal stored in the second capacitor. The method of claim 3, wherein And a data signal applied to the dummy pixel circuit is an average value or a mode value of a data signal applied to a pixel circuit in a predetermined region of the pixel portion. The method of claim 3, wherein One end of the second driving transistor is connected to the current sensing unit. The method of claim 1, The data correction unit receives a measurement value from the current sensing unit and converts it into a digital signal, a memory unit for storing a reference value of the current flowing in the pixel unit, the measured value and the memory converted in the digital conversion unit And a compensator for comparing a reference value stored in the unit and a compensator configured to generate a data compensation signal according to a comparison result of the comparator. The method of claim 6, And the reference value is a driving current initially generated by driving transistors of pixel circuits of the pixel portion. The method of claim 6, And a data compensation signal generated by the data compensator is transmitted to a data driver and applied to corresponding pixel circuits of the pixel part.

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