KR100681039B1 - Oled - Google Patents

Abstract

The present invention relates to an organic light emitting display device, a display device thereof, and a driving method thereof.

The present invention provides a data driver for applying one data signal to one data line, a scan driver for selectively applying a write scan signal and an erase scan signal to one scan line, and one data line and one scan line. When a plurality of organic light emitting elements are formed at these intersections, the data signal is stored by the write scan signal of the scan driver, and the data signal is erased by the erase scan signal, and the erase scan signal is applied according to the stored data signal. The present invention provides an organic light emitting display device including a pixel circuit unit for emitting a plurality of organic light emitting display elements to display an image.

Accordingly, the organic light emitting display device and the organic light emitting display device can be put to practical use.

Organic electroluminescence, digital drive, common scan line

Description

Organic electroluminescent element, display device thereof, driving method thereof {OLED}

1 is a conceptual diagram of a conventional active matrix organic light emitting display device.

2 is an equivalent circuit diagram of an organic light emitting display device having a conventional 3T1C pixel structure.

3 is a driving timing diagram of a conventional organic light emitting display device.

4 is a frame configuration diagram illustrating a method of digital driving using a 3T1C pixel structure of a conventional organic light emitting display device 13.

FIG. 5 is a waveform diagram illustrating application of scan signals when there are six scan lines of a conventional organic light emitting display device; FIG.

6 is a system configuration diagram of an organic light emitting display device according to a first embodiment of the present invention.

7 is an equivalent circuit diagram of an organic light emitting display device according to a first embodiment of the present invention.

8 is a driving waveform diagram of scan signals when there are six scan lines of an organic light emitting display device according to a first embodiment of the present invention;

9 is a system configuration diagram of an organic light emitting display device according to a second embodiment of the present invention.

10 is a driving waveform diagram of scan signals when there are six scan lines of an organic light emitting display device according to a second embodiment of the present invention;

The present invention relates to an organic light emitting display device, a display device thereof, and a driving method thereof.

Organic light emitting diodes (OLEDs) were self-luminous devices that emit fluorescent materials by recombination of electrons and holes. The organic light emitting display device including the organic light emitting display device is a wall-mounted or portable device because the response speed is faster, the DC driving voltage is lower, and the ultra-thin film is possible than the passive light emitting device which requires a separate light source like the liquid crystal display device. Application was possible.

Such an organic light emitting display device implements color using pixels in which red, blue, and green subpixels represent one color. At this time, the organic light emitting diode is an active matrix organic light emitting diode (active matrix) which is a method of driving using a simple matrix type organic light emitting diode (PMOLED) and a thin film transistor (TFT) as a method of driving a subpixel. OLED, AMOLED).

As the driving method of the active matrix organic light emitting diode (AMOLED), there are a current driving method, a voltage driving method, and a digital driving method. In the digital driving method of the active matrix organic light emitting diode (AMOLED), the thin film transistor (TFT) is turned on / off unlike the voltage compensation driving method or the current driving method using the TFT to drive the organic light emitting diode (OLED) with a constant current. The organic light emitting diode OLED was used as a switch to turn off.

1 is a conceptual diagram of a conventional active matrix type organic light emitting display device.

Conventionally, the active matrix organic light emitting display device 10 includes a pixel circuit part 12, a data driver 14, and two scan drivers 16 and 17.

In the conventional active matrix type organic light emitting display device 10, two first and second outputting sequential scan signals or selection signals are output through the scan line 19 to select a data line 18 to input data. It has a data driver 14 for inputting data to the data line 18 selected by the scan driver 16, 17 and the two scan drivers 16, 17.

At this time, the number of the scan drivers 16 and 17 is determined according to the pixel structure and the driving method, and the data driver 14 may be configured in the AMOLED panel or may be connected to the IC. In addition, at least one power supply line (20 in FIG. 2) exists to supply power to the pixel 13 to the active matrix organic light emitting display device 10.

In the pixel circuit 12 displaying the screen, pixels 13 including thin film transistors (TFTs) and organic light emitting diodes (OLEDs), such as 2T1C and 3T1C, were formed in a matrix form. Although the speed of the scan driver decreases, the 2T1C pixel structure does not display the screen during the scan period. However, the period of the screen being displayed is too short and the voltage applied to the power supply line VDD increases during one frame period. . In order to improve the problem of the 2T1C pixel structure, the 3T1C pixel structure and the digital driving method were devised, but the 3T1C pixel structure and the digital driving method also had problems as described below.

2 is a circuit diagram of an organic light emitting display device having a conventional 3T1C pixel structure.

The conventional organic light emitting diode 13 has a 3T1C (three TFT and one capacitor) pixel or pixel structure including first to third thin film transistors (T1 to T3) and one storage capacitor (Cst). It was.

In this case, the second thin film transistor T2 is a switch for transferring data input through the data line 18 according to a first scan signal or a write scan signal (W_Scan signal) supplied from the first scan driver 16. The storage capacitor Cst is a capacitor that stores the input data, and the first thin film transistor T1 is a switch that supplies current or voltage to the organic light emitting diode OLED by being turned on and off according to the input data. In addition, the third thin film transistor T3 shorts both ends of the storage capacitor Cst according to the second scan signal or the erase scan signal E_Scan signal supplied from the second scan driver 17 to store the storage capacitor ( It was a switch for erasing data stored in Cst) and turning off the first thin film transistor T1.

3 is a driving timing diagram of a conventional organic light emitting display device. An operation of the 3T1C pixel structure of the conventional organic light emitting display device will be described with reference to FIGS. 1 to 3.

1 to 3, the first scan signal W_Scan signal, which is an on / off control signal of the second thin film transistor T2 every one sub-field or one frame, is formed. When a low signal (on signal) is input through one scan line 19W, a data signal is input from the data driver 14 through the data line 18 to store the storage capacitor through the second thin film transistor T2. The first thin film transistor T1 is turned on / off according to this data signal, and the organic light emitting diode OLED is turned on / off to output a screen.

In addition, the signal stored in the storage capacitor Cst stores the data input while the first scan signal W_Scan signal is turned off, and the second scan signal E_Scan signal is transmitted through the second scan line 19E. When the low signal (on signal) is input, the third thin film transistor T3 is turned on to erase data stored in the storage capacitor Cst, and the first thin film transistor T1 is turned off to be discharged from the sub-field. The time for which the light emitting diode OLED was turned on was adjusted.

4 is a frame configuration diagram illustrating a method of digitally driving the 3T1C pixel structure of the conventional organic light emitting display device 13.

Referring to FIG. 4, one frame uses four first to fourth subfields SF1 to SF4 in order to display four bits, and each subfield time represents a binary weight. Had That is, each subfield time was SF2 = 2 * SF1, SF3 = 4 * SF1, SF4 = 8 * SF1. Accordingly, when the data “1010” is displayed, the organic light emitting diode OLED is emitted by turning on the first thin film transistor T1 only during the periods SF4 and SF2.

In the 3T1C pixel structure, turning on the pixel 13 was controlled by using the first scan signal (W_Scan signal) and off by using the second scan signal (E_Scan signal). If the period of the subfield is longer than the period of the first scan signal (W_Scan signal), as shown in SF3 and SF4 of FIG. 4, since the new data is input in the next subfield, the second scan signal E_Scan may or may not be used. However, if the period of the subfield is shorter than the period of the first scan signal (W_Scan signal) like SF1 and SF2, the subfield period is controlled by controlling the time that the pixel 13 is turned on by using the second scan signal (E_Scan signal). It was.

5 is a waveform diagram illustrating application of scan signals when there are six scan lines of a conventional organic light emitting display device.

Referring to FIG. 5, the first scan signal (W_Scan signal) outputs a signal sequentially turned on from # 1 to # 6, and data is input in accordance with the first scan signal (W_Scan signal). On the other hand, the second scan signal (E_Scan signal) also outputs a signal sequentially turned on signal # 1 to # 6 to erase the data stored in the pixel (13). In the case of the first subfield, since the second scan signal # 1 (E_Scan signal # 1) is on after two scan times after the first scan signal # 1 (W_Scan signal # 1) is turned on, the first The subfield outputs luminance for two scan times.

In addition, in the case of the second subfield, since the second scan signal # 1 is turned on after four scan times after the first scan signal # 1 (W_Scan signal # 1) is turned on, the second subfield has four scan times. The brightness was output. As described above, after adjusting the time when the second scan signal is input after the first scan signal is input, the ratio of the luminance output by the pixel 13 for each subfield is adjusted.

However, the 3T1C pixel structure of the organic light emitting display device has a problem in that the aperture ratio of the pixel 13 itself is lower than that of the 2T1C pixel structure due to the larger number of thin film transistors and scan lines.

In addition, the digital driving method using the 3T1C pixel structure of the conventional organic light emitting display device has a problem that the speed of the scan driving units 16 and 17 decreases, and the period of time actually displayed on the screen in one frame period is longer.

In order to solve the above problems, the present invention provides an organic light emitting display device, a display device, and a driving method thereof in which an aperture ratio increases by digitally driving a 2T1C pixel structure like a 3T1C pixel structure to reduce the number of thin film transistors or scan lines. Its purpose is to.

In addition, the present invention increases the luminance life of the device by digitally driving the 2T1C pixel structure like the 3T1C pixel structure because the current density of the current flowing when the same luminance is higher is smaller as the aperture ratio is higher, and the lower the current density is, the better the luminance life is. Another object of the present invention is to provide an organic light emitting display device, a display device, and a driving method thereof.

In order to achieve the above technical problem, the present invention provides a data driver for applying one data signal to one data line, a scan driver for selectively applying a write scan signal and an erase scan signal to one scan line, and one A plurality of organic light emitting diodes are formed at the intersection of one data line and one scan line, and the data signal is stored by the write scan signal of the scan driver, and the data signal is erased by the erase scan signal. Accordingly, an organic light emitting display device including a pixel circuit unit which emits a plurality of organic light emitting diodes and displays an image until a clear scan signal is applied thereto is provided.

In this case, the organic light emitting diode is connected to an organic light emitting diode that emits light by a signal current, a storage capacitor that stores a data signal when a write scan signal and a data signal are applied, and a power supply voltage and a light emitting diode to connect to the write scan signal. The first thin film transistor supplies a signal current to the organic light emitting diode in proportion to the stored data and stops supplying the signal current to the organic light emitting diode according to the erase scan signal, and a data signal according to the write scan signal and the erase scan signal. It may include a second thin film transistor for storing or erasing in the storage capacitor.

In addition, the first and second thin film transistors may be PMOS transistors.

The scan driver may include a first scan driver that supplies a write scan signal to one common scan line, and a second scan driver that supplies an erase scan signal to one common scan line.

The apparatus may further include a selection unit for selecting whether to apply the write scan signal of the first scan driver or the erase scan signal of the second scan driver to one common scan line.

The selector may be first and second switches formed between the first scan driver and the second scan driver and the common scan line.

In addition, the selector causes the first scan driver and the second scan driver to output the write scan signal when the first scan driver and the second scan driver output the write scan signal, and the first control signal and the second scan driver to make the first scan driver and the second scan driver high-impedance, respectively. The control signal may be supplied to the first scan driver and the second scan driver.

In another aspect, the present invention provides an organic light emitting diode that emits light by a signal current, a storage capacitor that stores a data signal when a write scan signal and a data signal are applied, and a write scan signal connected between a power supply voltage and a light emitting diode. And a first thin film transistor which supplies a signal current to the organic light emitting diode in proportion to the stored data and stops supplying the signal current to the organic light emitting diode according to the erase scan signal, and a write scan signal connected to one scan line. Provided is an organic light emitting display device including a second thin film transistor to selectively apply a erase scan signal to store or erase a data signal in a storage capacitor according to a write scan signal and an erase scan signal.

In this case, the first and second thin film transistors may be PMOS transistors.

In another aspect, the present invention provides a scan signal input step of dividing a frame into a plurality of subfields and sequentially inputting a write scan signal and an erase scan signal through the same common scan line for each subfield; A data signal input step of applying a data signal to supply a signal current to the light emitting diode, and an optional step of selecting a write scan signal and a clear scan signal to determine whether to supply or stop the signal current to the organic light emitting diode A method of driving a display device is provided.

In this case, the selection step may be a switching step of switching whether the write scan signal and the erase scan signal are connected to the common scan line.

In this case, the selection step may be a control step of determining whether to provide the write scan signal and the erase scan signal to the common scan line.

In addition, one frame may consist of six subfields.

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

Example 1

6 is a system configuration diagram of an organic light emitting display device according to a first embodiment of the present invention.

Referring to FIG. 6, the active matrix organic light emitting display device 30 according to the first embodiment of the present invention includes a pixel circuit 32, a data driver 34, and two scan drivers 36 and 37. Doing.

In the pixel circuit unit 32 displaying a screen, pixels 33 including a thin film transistor (TFT) and an organic light emitting diode (OLED) having a 2T1C pixel structure are formed in a matrix form.

In addition, the active matrix type organic light emitting display device 30 includes two first and second output sequential scan signals or selection signals through the common scan line 39 in order to select a data line 38 to input data. It has a data driver 34 for inputting data to the data line 38 selected by the second scan driver 36, 37 and the two scan drivers 36, 37.

In this case, the first scan driver 36 for outputting a scan waveform for writing data to the pixel 30 and the second scan driver 37 for erasing data stored in the pixel 30 are respectively formed. It is connected to one common scan line 39 through a switch controlled by the first scan signal switches Scan SW1 and 42 and the second scan signal switches Scan SW2 and 44. When the output of the first scan driver 36 is applied to the scan line 39 by the first scan signal switch 42, the data is output to the data line 38, and the second scan signal switch 44 is used to output the data. When the output of the two scan driver 39 is applied to the scan line 39, an off signal of the pixel 33 is applied to the data line 38 to convert the 2T1C pixel structure into a 3T1C pixel structure using one scan line 39. Can be driven as

In this case, the data driver 34 may be configured on a panel or may be connected to an IC. In addition, the data driver 34 may be divided into two or more to supply the data signal to the pixel circuit unit 32. In addition, in order to supply power to the pixel 33 to the active matrix type organic light emitting display device 30, there is one power supply line (40 in FIG. 7).

7 is a circuit diagram of an organic light emitting display device according to a first embodiment of the present invention.

Referring to FIG. 7, the organic light emitting display device 33 according to the first embodiment of the present invention includes a first and second thin film transistors (PT1, PT2) and one storage capacitor (PMOS transistor), which are PMOS transistors. 2T1C (three TFTs and one capacitor) pixel or pixel structure composed of Cst).

In this case, the first thin film transistor PT1 is a switch that is turned on / off according to the input data to supply current or voltage to the organic light emitting diode OLED.

The second thin film transistor PT2 not only transfers the data input through the data line 38 according to the first scan signal or the write scan signal W_Scan signal supplied from the first scan driver 36, but also the second scan. The both ends of the storage capacitor Cst are shorted according to the second scan signal or the erase scan signal E_Scan signal supplied from the driver 37 to erase data stored in the storage capacitor Cst, and the first thin film transistor ( It is a switch for turning off PT1). Since the second thin film transistor PT2 is connected to the first scan driver 36 and the second scan driver 37 through one common scan line 39, the first scan signal switch 42 and the second scan. The scan driver connected by the signal switch 44 is selected.

The storage capacitor Cst is a capacitor that stores the input data.

8 is a driving waveform diagram of scan signals when there are six scan lines of an organic light emitting display device according to a first embodiment of the present invention.

Referring to FIG. 8, first scan signals # 1 to # 6 (W_Scan # 1 to # 6) that are driving waveforms of the first scan driver 36 and second scan signals that are drive waveforms of the second scan driver 37 are described. # 1 to # 6 (E_Scan # 1 to # 6) output the same waveform as the driving waveform of the 3T1C pixel structure of the conventional organic light emitting display device of FIG. 5, and the first scan driver 36 and the second scan driver 37 Scan signals # 1 to # 6 (scan) to be applied to the second thin film transistor PT2 of FIG. 7 at the bottom of FIG. 8 by adjusting the first scan signal switch 42 and the second scan signal switch, which are output switch control signals of FIG. Output two scan waveforms as in # 1 ~ # 6).

As shown in the lowermost part of FIG. 8, when the output of the first scan driver 36 is applied to the scan line 39 by the first scan signal switch 42, the data signal is input to the pixel 33. When the data is stored in the storage capacitor Cst and the output of the second scan driver 37 is applied to the common scan line 39 by the second scan signal switch 44, the off signal of the pixel 33 is output. The pixel 33 is turned off by input.

As a result, the organic light emitting display device 30 according to the first embodiment of the present invention can digitally drive the organic light emitting display device having the 2T1C pixel structure like the organic light emitting display device having the 3T1C pixel structure. Accordingly, the aperture ratio can be increased by reducing the number of thin film transistors or scan lines while maintaining the advantages of the digital driving method of the 3T1C pixel structure.

Example 2

9 is a system configuration diagram of an organic light emitting display device according to a second embodiment of the present invention.

Referring to FIG. 9, the organic light emitting display device 50 according to the second embodiment of the present invention includes a pixel circuit 52, a data driver 54, and two scan drivers 56 and 57. It has the same 2T1C pixel structure of the organic light emitting display device as 7 and the second thin film receives the first scan signal and the second scan signal of the first scan driver 56 and the second scan driver 57 through the common scan line 59. The organic light emitting display device 30 according to the first embodiment is the same in that the data signal is output to the transistor PT2 to write or erase the data signal.

However, the organic light emitting display device 50 according to the second exemplary embodiment of the present invention replaces the first scan signal switch 42 and the second scan signal switch 44 with the first scan driver 56 and the second scan. The driver 57 outputs a previous scan signal or a high-impedance state according to the first control signal Scan_OE1 and the second control signal Scan OE2 which are output control signals, respectively. Different from the organic light emitting display device 30 according to the embodiment. At this time, the high-impedance state is a state in which the output switches are turned off and do not affect the output.

That is, the organic light emitting display device 50 according to the second exemplary embodiment of the present invention erases the data stored in the first scan driver 56 and the pixel 53 that output a scan waveform for writing data to the pixel 53. The second scan driver 57 is connected to one common scan line 59, and the first and second control signals Scan, which are output control signals of the first scan driver 56 and the second scan driver 57, are scanned. OE1, OE2). If the first control signal Scan OE1 is on, the output of the first scan driver 56 is applied to the common scan line 59. If the second control signal Scan OE2 is off, the second scan driver 57 is applied. ) Is a high-impedance state, the waveform applied to the common scan line 59 becomes the output of the first scan driver 56. At this time, data is applied to the data line 58 to store the data in the storage capacitor Cst.

On the other hand, if the first control signal Scan OE1 is an off signal, the output of the first scan driver 56 is in the high-impedance state, and if the second control signal Scan OE2 is the on signal, the second scan driver 57 An output is applied to the common scan line 59, at which time the off signal of the pixel 53 is input to the data line 58.

In this way, the output of the first and second scan drivers 56 and 57 is controlled through one common scan line 59 by the first and second control signals Scan OE1 and OE2, and the data line A data signal and an off signal can be applied to 58 to drive the 2T1C pixel structure in the same manner as the 3T1C pixel structure using one common scan line 59.

FIG. 10 is a driving waveform diagram of scan signals when six scan lines are used in an organic light emitting display device according to a second exemplary embodiment of the present invention.

Referring to FIG. 10, the first scan signals # 1 to # 6 (W_Scan # 1 to # 6), which are driving waveforms of the first scan driver 56, are the same as in FIG. 8 when the first control signal Scan OE1 is turned on. The same waveform as the first scan signal is output, and when the first control signal Scan OE1 is off, it is in a high-impedance state.

The second scan signals # 1 to # 6 (E_Scan # 1 to # 6), which are output waveforms of the second scan driver 57, are the same as the second scan signal shown in FIG. 8 when the second control signal Scan OE2 is on. The waveform is output and a high-impedance state is output when the second control signal Scan OE2 is off.

When the first and second control signals Scan OE1 and Scan OE2, which are output control signals of the first and second scan drivers 56 and 57, are alternately turned on and off with FIG. 10, scan signals # 1 to # at the lower part of FIG. 10. As shown in 6 (Scan # 1 to # 6), two scan waveforms can be output to one common scan line 59.

At this time, when the output of the first scan driver 56 is applied to the common scan line 59 by the first control signal Scan OE1 as shown in FIG. 10, the data signal is input to the storage capacitor of the pixel 53. Cst), and when the output of the second scan driver 59 is applied to the common scan line 59 by the second control signal Scan OE2, the off signal of the pixel 53 is input to the pixel 53. Off).

As a result, the organic light emitting display device 50 according to the second embodiment of the present invention can also digitally drive the organic light emitting display device having the 2T1C pixel structure like the organic light emitting display device having the 3T1C pixel structure. Accordingly, the aperture ratio can be increased by reducing the number of thin film transistors or scan lines while maintaining the advantages of the digital driving method of the 3T1C pixel structure.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. I can 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.

According to this configuration, the present invention has the effect of increasing the aperture ratio by digitally driving the 2T1C pixel structure like the 3T1C pixel structure by reducing the number of thin film transistors or scan lines.

In addition, in the present invention, since the current density of the current flowing at the same luminance is smaller as the aperture ratio is higher, and the luminance density is better as the current density is lower, the 2T1C pixel structure is digitally driven like the 3T1C pixel structure to increase the luminance life of the device. Can be.

Accordingly, the organic light emitting display device and the organic light emitting display device can be put to practical use.

Claims (13)

A data driver for applying one data signal to one data line; A scan driver for selectively applying a write scan signal and an erase scan signal to one scan line; A plurality of organic light emitting diodes are formed at a position where the one data line and the one scan line cross each other, the data signal is stored by a write scan signal of the scan driver, and the data is erased by the erase scan signal. And a pixel circuit unit which erases a signal and emits the plurality of organic light emitting diodes to display an image until the erase scan signal is applied according to the stored data signal. The method of claim 1, The organic light emitting device is An organic light emitting diode emitting light by a signal current; A storage capacitor which stores the data signal when the write scan signal and the data signal are applied; Connected between a power supply voltage and the light emitting diode to supply a signal current to the organic light emitting diode in proportion to data stored according to the write scan signal, and then stop supply of the signal current to the organic light emitting diode according to the erase scan signal. A first thin film transistor; And a second thin film transistor configured to store or erase the data signal in the storage capacitor according to the write scan signal and the erase scan signal. The method of claim 2, And the first and second thin film transistors are PMOS transistors. The method of claim 3, wherein The scan driver includes an first scan driver for supplying the write scan signal to the one common scan line, and a second scan driver for supplying the erase scan signal to the one common scan line. Light emitting display. The method according to any one of claims 1 to 4, And a selector for selecting whether to apply the write scan signal of the first scan driver or the erase scan signal of the second scan driver to the one common scan line. The method of claim 5, And wherein the selector is a first switch or a second switch formed between the first scan driver, the second scan driver, and the common scan line. The method of claim 6, The selector is configured to cause the first scan driver and the second scan driver to output the write scan signal when the first scan driver and the second scan driver output the write scan signal, and to turn the first scan driver and the second scan driver into a high-impedance state. And a control signal and a second control signal are supplied to the first scan driver and the second scan driver. An organic light emitting diode emitting light by a signal current; A storage capacitor for storing the data signal when the write scan signal and the following data signal are applied; Connected between a power supply voltage and the light emitting diode to supply a signal current to the organic light emitting diode in proportion to the data stored according to the write scan signal described below, and then stop supply of the signal current to the organic light emitting diode according to the erase scan signal. A first thin film transistor; An organic field connected to one scan line and selectively including a write scan signal and an erase scan signal to store or erase the data signal in the storage capacitor according to the write scan signal and the erase scan signal; Light emitting element. The method of claim 8, The first and second thin film transistors are organic light emitting diodes, characterized in that the PMOS transistor. A scan signal input step of dividing one frame into a plurality of subfields and sequentially inputting a write scan signal and an erase scan signal for each subfield through the same common scan line; A data signal input step of applying a data signal to supply a signal current to the organic light emitting diode during the subfield; And selecting the write scan signal and the erase scan signal to determine whether to supply a signal current to the organic light emitting diode or to stop the organic light emitting display device. The method of claim 10, And wherein the selecting step is a switching step of switching whether the write scan signal and the erase scan signal are connected to the common scan line. The method of claim 10, And wherein the selecting step is a control step of determining whether to provide the write scan signal and the erase scan signal to the common scan line. The method according to claim 11 or 12, wherein And one frame includes six subfields.

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