KR101072769B1 - driving circuit for passive matrix organic light emitting diode - Google Patents

Abstract

The present invention discloses a passive organic light emitting device driving circuit. According to this, the driving current supply transistors of the respective output circuit sections are turned on when the driving current switching transistors of the respective output circuit sections are turned on by electrically connecting the outputs of the driving current supply transistors in the output circuit sections of the data driver section to one common terminal. The driving current deviation of each data line due to the deviation of the threshold voltage can be mutually corrected to supply the same, and the organic light emitting diode of the pixel corresponding to each data line is driven with the same amount of driving current averaged by the common terminal. Therefore, the luminance non-uniformity between the data lines can be prevented and the quality of the passive organic light emitting device can be improved.

Passive organic light emitting device, drive circuit, data line, drive current, drive current supply transistor, common terminal, brightness, threshold voltage

Description

Driving circuit for passive matrix organic light emitting diode

1 is a circuit diagram showing a driving circuit of a general passive organic light emitting diode (PMOLED), a state diagram of the switching switch of the selection switch for the scan driver during precharge.

Fig. 2 is a circuit diagram showing a driving circuit of a general passive organic light emitting diode (PMOLED), showing a switching state of a selection switch for a scan driver in selecting a first scan line.

3 is a detailed circuit diagram showing an output circuit section for each data line of a conventional passive organic light emitting diode (PMOLED).

4 is a circuit diagram showing a passive organic light emitting device driving circuit according to the present invention.

Fig. 5 is a detailed circuit diagram showing one output circuit portion of a passive organic light emitting element driving circuit according to the present invention, in which a common terminal is electrically connected to a driving current supply transistor in the output circuit portion.

Fig. 6 is a detailed circuit diagram showing each output circuit portion of a passive organic light emitting element driving circuit according to the present invention, in which a common terminal is electrically connected to a driving current supply transistor in each output circuit portion.

7 is a detailed circuit diagram illustrating each output circuit part of a passive organic light emitting device driving circuit according to the present invention, in which a common terminal is electrically connected to a driving current supply transistor in an output circuit part of each data line corresponding to red, green, and blue colors. Schematic.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive matrix organic light emitting diode (PMOLED) driving circuit, and more particularly, passive organic light emitting diodes for preventing luminance deviation between data lines by supplying the same driving current to each data line. It relates to an element driving circuit.

Recently, various flat panel displays have been developed to solve heavy weight and large volume, which are disadvantages of conventional cathode ray tubes (CRTs). These flat panel displays include plasma display panels (PDPs), liquid crystal displays (LCDs), field emission displays (FEDs), and organic light emitting diodes (OLEDs). Etc.

The organic light emitting diode is receiving great attention as a next generation flat panel display, and passive matrix organic light emitting diode (PMOLED) and active matrix organic light emitting diode (active matrix organic light emitting) according to the driving method of the organic light emitting diode. diode: AMOLED).

The driving section for emitting light of the passive organic light emitting diode (PMOLED) includes a precharging section for precharging charges to parasitic capacitors of pixels present in the organic light emitting diode panel, and a driving section for driving the pixels of the organic light emitting diode. It is divided into a driving section and a discharging section for discharging a charge.

1 and 2 are circuit diagrams illustrating a driving circuit of a general passive organic light emitting diode (PMOLED). FIG. 1 is a diagram illustrating a switching state of a selection switch for a scan driver during precharge, and FIG. 2 illustrates a first scan line selection. Fig. 1 shows the switching state of the selection switch for the scan driver.

As shown in FIGS. 1 and 2, a general passive organic light emitting diode driving circuit includes a panel 10, a scan driver 20, and a data driver 30.

Here, the panel unit 10 includes a transparent insulating substrate (not shown), for example, a glass substrate, a plurality of pixels 11 arranged in a matrix form on the substrate, and a plurality of substrates intersecting each other on the substrate. Scan lines 13-1 to 13-n and data lines 15-1 to 15-n. The scan driver 20 selectively drives each scan line 13-1 to 13-n, and the data driver 30 selects and drives each data line 15-1 to 15-n. 11) emits light.

In addition, the scan driver 20 includes a plurality of selection switches 21-1 to 21-n for selectively driving the scan lines 13-1 to 13-n, and each of the selection switches 21-1 to. 21-n is electrically connected to the scan lines 13-1 to 13-n in a one-to-one correspondence. The scan driver 20 switches and connects the select switch of the corresponding scan line to ground in order to selectively drive any desired scan line. For example, to selectively emit light of the first scan line 13-1, the scan driver 20 may include a selection switch 21-1 to which the first scan line 13-1 is connected as shown in FIG. 2. Switch only to ground.

The data driver 30 also controls a plurality of output circuits 31-1 for controlling output to each of the data lines 15-1 to 15-n to selectively emit light of each pixel 11 of the panel unit 10. ˜31-n). Each output circuit section 31-1 to 31-n uses pre-charge current and drive to the corresponding data lines 15-1 to 15-n using six transistors M1 to M6 as illustrated in FIG. Output current.

Referring to the process of causing each pixel 11 of the panel unit 10 to emit light using the output circuit units 31-1 to 31-n as described above, the data driver 30 may be configured as shown in FIG. 3. The precharge current supply transistor in the state where the precharge current switching transistor M5 of the output circuits 31-1 to 31-n is turned on and the drive current switching transistor M6 is turned off. By supplying a precharge current through the M3 and M4, the parasitic capacitor Cp of the organic light emitting diode of each pixel 11 is precharged, followed by turning off the precharge current switching transistor M5 and switching the drive current. By driving the driving current through the driving current supply transistors M1 and M2 in the state where the transistor M6 is turned on, the pixel of the selected first scan line 11-1 is made to emit light as shown in FIG. 2. In this case, the driving current supplied to the pixel is represented by Equation 1 below.

However, in the conventional organic light emitting diode driving circuit, the transistors M1 to M4 for the respective output circuits 31-1 to 31-n corresponding to the respective data lines 15-1 to 15-n are the same. The gate voltage between the transistors M1 to M4 is the same for each of the output circuits 31-1 to 31-n. For example, the gate voltage of the transistor M1 for the output circuit portion 31-1 is the same as the gate voltage of the transistor M1 for the output circuit portion 31-2. Similarly, the gate voltages of the transistors M2, M3, and M4 for the output circuit 31-1 are also equal to the gate voltages of the transistors M2, M3, and M4 for the output circuit 31-2.

Therefore, since the gate voltages of the transistors M1 to M4 for the respective output circuits 31-1 to 31-n are designed to be equally applied to all data lines 15-1 to 15-n, theoretically, all It can be said that the same amount of current flows through the data lines 15-1 through 15-n, respectively. However, in practice, in the manufacturing process of the passive organic light emitting device, all the data lines are because the threshold voltage Vth of the transistors M1 to M4 manufactured for each data line 15-1 to 15-n has a slight deviation. A difference in the amount of current flowing through 15-1 to 15-n occurs, and as a result, there is a problem that luminance unevenness occurs between the data lines 15-1 to 15-n. That is, due to the current deviation in the precharge section, the luminance between the data lines 15-1 to 15-n may be uneven due to over precharge or under precharge, and also during driving. There is a problem that the luminance is more uniform between the data lines 15-1 to 15-n due to the current deviation being added.

Accordingly, an object of the present invention is to supply the driving current of each data line when the driving current switching transistor is turned on by connecting the outputs of the driving current supplying transistors of all the data lines for the passive organic light emitting device to one common terminal. The driving current is equally supplied to the pixel by mutually correcting the deviation of the driving current due to the variation of the threshold voltage of the transistor.

Another object of the present invention is to prevent the luminance non-uniformity between data lines by supplying the same drive current amount averaged using one common terminal by the driving current supply transistor of each data line for the passive organic light emitting device.

In the passive organic light emitting device driving circuit according to the present invention for achieving the above object, a plurality of data lines and a plurality of scan lines are arranged to cross each other, a plurality of organic light emitting diodes corresponding to the data line and the scan line A passive organic light emitting device panel unit disposed; A data driver having a plurality of output circuits electrically connected to each of the data lines in a one-to-one correspondence; And a scan driver having a plurality of select switches electrically connected to each of the scan lines in a one-to-one correspondence, wherein each of the drive current supply transistors in each of the output circuits is configured to supply the same drive current to each of the data lines. The outputs are all electrically connected to one common terminal, and one or more driving current supply transistors of each of the output circuit units are connected in series, and the drain terminal and the source terminal of the series-connected driving current supply transistors are one common. It is characterized in that it is electrically connected to the terminal.

Preferably, the outputs of the driving current supply transistors of each of the output circuit units may be electrically connected to all common terminals corresponding to the respective colors.

Preferably, the outputs of the driving current supply transistors of each of the output circuit parts corresponding to red of the output circuit parts are all electrically connected to the common terminal for red color, and the outputs of the driving current supply transistors of each of the output circuit parts corresponding to green color are output. The silver may be electrically connected to the common terminal for green, and the output of the driving current supply transistor of each of the output circuit units corresponding to the blue may be electrically connected to the common terminal for blue.

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Hereinafter, a passive organic light emitting device driving circuit according to the present invention will be described in detail with reference to the accompanying drawings. The same code | symbol is attached | subjected to the part which has the same structure and the same action as the conventional part.

4 is a circuit diagram showing a passive organic light emitting device driving circuit according to the present invention. Referring to FIG. 4, in the passive organic light emitting diode driving circuit of the present invention, each of the output circuits 41-1 to 41-n of the data driver 30 shown in FIGS. 1 and 2 includes transistors M1 and M2. Although the output of the circuit is not electrically connected to the common terminal, each of the output circuits 41-1 to 41-n of the data driver 40 of the present invention has a driving current supply transistor M1, as shown in FIG. 5. Except for the difference of electrically connecting the output of M2) to the common terminal COM, it is the same as the conventional organic light emitting device driving circuit.

That is, each of the output circuits 41-1 through 41-n is an output circuit for controlling the output to each of the data lines 15-1 through 15-n. As shown in FIG. In order to output the precharge and driving current, a plurality of transistors, for example, six transistors M1 to M6 are included. Furthermore, the drain of the driving current supply transistor M1 of each of the output circuit portions 41-1 to 41-n to connect or disconnect the driving current output to each of the data lines 15-1 to 15-n. The portion corresponding to the source of the driving current supply transistor M2 is configured to be connected to one common terminal COM.

In other words, as shown in FIG. 6, two output circuit parts 41-1 to 41-n of the data driver 40 connected in a one-to-one correspondence with each data line 15-1 to 15-n are provided. The driving current supply transistors M1 and M2 are connected in series, and the drain terminal of the transistor M1, which is a series connection terminal of the transistors M1 and M2, and the source terminal of the transistor M2 are connected to one common terminal COM. And supplying driving current to each output circuit portion 41-1 to 41-n when the driving current switching transistor M6 of each output circuit portion 41-1 to 41-n is turned on. Compensating the deviation of the drive current between the data lines 15-1 to 15-n due to the deviation of the threshold voltages of the transistors M1 and M2, and switching the same drive current averaged by the common terminal COM to drive current switching. All data by outputting to the corresponding data lines 15-1 to 15-n through the transistor M6. The same driving current may be supplied to the pixels 11 corresponding to the lines 15-1 to 15-n.

Also, in the case of a full color passive organic light emitting diode, each of the red, green, and blue pixels has different organic materials deposited for each color, so that the electrostatic capacitance of the parasitic capacitor of each pixel is different. Since the capacitance is different and the driving current is different as a result, the drain terminal of the driving current supply transistor M1 of each data line 15-1 to 15-n and the source terminal of the driving current supply transistor M2 are connected. In the configuration to connect all to the common terminal COM, it is assumed that each of the data lines 15-1 to 15-n for three-color light emission of red, green, and blue are present. In this case, after configuring one common terminal, for example, common terminals COM1 to COM3 (not shown) corresponding to each color, red data lines are between red data lines, and green data lines are green. Between the data lines, the blue data line is blue A common terminal corresponding to the drain terminal of the driving current supply transistor M1 and the source terminal of the driving current supply transistor M2 in each output circuit portion 41-1 to 41-n between the data lines is, for example, common. Both terminals can be connected to either COM1 or COM2 or COM3 (not shown).

That is, as shown in FIG. 7, the drain terminal of the driving current supply transistor M1 in each of the output circuit portions 41-1 and 41-4 for the red data lines 15-1 and 15-4. The source terminal of the driving current supply transistor M2 is electrically connected to a common terminal corresponding to red color, for example, the common terminal COM1. The drain terminal of the driving current supply transistor M1 and the source of the driving current supply transistor M2 in the respective output circuits 41-2 and 41-5 for the green data lines 15-2 and 15-5. The terminals are all electrically connected to a common terminal corresponding to green, for example common terminal COM2. The drain terminal of the driving current supply transistor M1 and the source of the driving current supply transistor M2 in the respective output circuit portions 41-3 and 41-6 for the blue data lines 15-3 and 15-6. The terminals are all electrically connected to a common terminal corresponding to blue, for example common terminal COM3.

7 shows that two data lines exist for each color, but in reality, even when there are more data lines, the driving current in each output circuit portion for each data line in the same manner is present. It is apparent that both the drain terminal of the supply transistor M1 and the source terminal of the driving current supply transistor M2 can be electrically connected to both common terminals corresponding to the corresponding color.

The light emitting process will be described using a passive organic light emitting device driving circuit having such a structure.

First, in order to emit light of the passive organic light emitting diode, the parasitic capacitor Cp of each pixel needs to be precharged. During this precharge period, the scan driver 20 supplies all of the select switches 21-1 to 21-n. Electrically connected to the terminal Vddhs so that all the pixels 31 act as parasitic capacitors Cp, and the data driver 40 is a precharge current switching transistor of each of the output circuits 41-1 to 41-n. The precharge current is supplied through the third and fourth precharge current supply transistors M3 and M4 while the M5 is turned on and the driving current switching transistor M6 is turned off.

At this time, the precharge currents of the respective output circuits 41-1 to 41-n are output to the corresponding data lines 15-1 to 15-n through the respective precharge current switching transistors M5. The parasitic capacitor Cp of each pixel is precharged as it flows to the parasitic capacitor Cp of each pixel electrically connected to the data lines 15-1 to 15-n.

After the precharging of the parasitic capacitor Cp of each pixel is completed, the scan driver 20 transfers to the selected scan line, for example, the first scan line 13-1, as the transition from the precharge period to the driving period. Switching the electrically connected select switch 21-1 from the power supply terminal Vddhs to the ground terminal so that the pixel electrically connected to the first scan line 13-1 acts as an organic light emitting diode instead of the parasitic capacitor Cp. Meanwhile, the data driver 40 turns off the precharge current switching transistor M5 and turns on the driving current switching transistor M6 to drive the first and second driving current supply transistors M1 and M2. By supplying current, only the pixel corresponding to the selected first scan line 13-1 emits light.

At this time, the drain terminal of the first driving current supply transistor M1 and the second driving current supply in the output circuit portions 41-1 to 41-n electrically connected to the respective data lines 15-1 to 15-n. Since the source terminal of the transistor M2 is electrically connected to one common terminal COM, the source terminal of the transistor M2 is supplied through the first and second transistors M1 and M2 from each output circuit part 41-1 to 41-n. The driving current flows to the common terminal COM, and each output circuit portion 41-1 to 41-n is driven as the driving current of each output circuit portion 41-1 to 41-n is concentrated by the common terminal COM. The driving currents between the data lines 15-1 to 15-n and the output circuits 41-1 to 41-n electrically connected to the data lines 15-1 to 15-n due to the threshold voltage deviation of the transistors M1 and M2 are mutually corrected.

Accordingly, as the driving currents of all the output circuit parts 41-1 to 41-n are concentrated at the common terminal COM, the output circuit parts 41-1 to electrically connected to the respective data lines 15-1 to 15-n. After the amount of drive current between 41-n is mutually corrected, the averaged drive current, that is, the same drive current, is again applied to the corresponding data line through the drive current switching transistor M6 of each output circuit portion 41-1 to 41-n. It is output as (15-1 to 15-n). The output driving current flows to the organic light emitting diodes of the pixels electrically connected to the data lines 15-1 to 15-n, and thus the organic light emitting diodes of the pixels corresponding to all the data lines 15-1 to 15-n are generated. The diodes emit light at the same drive current value.

Therefore, the present invention drives the organic light emitting diodes of the pixels corresponding to each of the data lines 15-1 to 15-n by the same driving current, so that the data lines 15-1 to 15-n due to the deviation of the driving currents. The luminance nonuniformity phenomenon can be prevented.

Meanwhile, the present invention exemplifies a configuration in which two driving current supply transistors M1 and M2 and two precharge current supply transistors M3 and M4 are connected in series, but one may be configured.

As described above, the passive organic light emitting diode driving circuit according to the present invention electrically connects the outputs of the driving current supply transistors in each output circuit portion of the data driver to one common terminal for switching the driving current of each output circuit portion. When the transistor is turned on, the drive current deviation of each data line due to the deviation of the threshold voltage of the drive current supply transistor of each output circuit part can be controlled to be supplied equally, and the same amount of drive current averaged by the common terminal is further controlled. The organic light emitting diodes of the pixels corresponding to each data line may be driven to prevent luminance unevenness between the data lines and to improve the quality of the organic light emitting diodes. On the other hand, the present invention is not limited to the contents described in the drawings and detailed description, it is obvious to those skilled in the art that various modifications can be made without departing from the spirit of the invention. .

Claims (4)

A passive organic light emitting device panel unit in which a plurality of data lines and a plurality of scan lines are arranged to cross each other, and a plurality of organic light emitting diodes are disposed corresponding to the data lines and the scan lines; A data driver having a plurality of output circuits electrically connected to each of the data lines in a one-to-one correspondence; And A scan driver having a plurality of selection switches electrically connected to each of the scan lines in a one-to-one correspondence; In order to supply the same drive current to each of the data lines, the outputs of the respective drive current supply transistors in the plurality of output circuit sections are all electrically connected to one common terminal, One or more driving current supply transistors of each of the output circuit units are connected in series, and the drain and source terminals of the series connected driving current supply transistor are electrically connected to one common terminal. Driving circuit. The passive organic light emitting diode driving circuit according to claim 1, wherein the outputs of the driving current supply transistors in the plurality of output circuit sections are all electrically connected to a common terminal corresponding to each color. 3. The driving current supply transistor of claim 2, wherein the outputs of the driving current supply transistors of each of the output circuit parts corresponding to red of the output circuit part are electrically connected to the common terminal for red color, and each of the output circuit parts of the output circuit part corresponding to green color is formed. The output of the passive organic light-emitting device driving circuit, characterized in that all of the output is electrically connected to the common terminal for green, the output of the drive current supply transistor of each of the output circuit portion corresponding to the blue are all electrically connected to the common terminal for blue. delete

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