KR100578840B1 - A power supply in a lighting emitting device - Google Patents

Abstract

The present invention relates to a power supply for a light emitting display device having a reference potential selection circuit for providing a stable data voltage to a data driver of the light emitting display device.

The power supply device for a light emitting display device according to the present invention includes an external reference potential supply unit for supplying an external reference potential (VCIRex); A reference potential generator which converts the external power into a stabilized DC reference potential VCIR when the voltage of the external power Vci input from the outside changes; A reference potential selection unit for selecting and outputting any one reference potential input from the external reference potential supply unit or the reference potential generation unit; And a voltage converter configured to convert the stabilized reference potential VCIR 'output from the reference potential selector into a plurality of internal DC power supplies used in the driver.

According to the present invention, by selectively providing a stable voltage among the stabilized reference potential and the external reference potential inside the data driver of the light emitting display device, it is possible to prevent nonuniformity such as luminance due to a change in the data voltage.

Organic EL, power supply, reference potential, LDO, data driver

Description

Power supply for a light emitting display device {A power supply in a lighting emitting device}

1 is a diagram showing the light emission principle of an organic EL.

2 is a diagram illustrating a pixel circuit of a general organic EL.

3 is a diagram illustrating an organic EL display panel using an active driving method using a thin film transistor (TFT) according to an embodiment of the present invention.

4 is a schematic block diagram of an organic EL display device according to an embodiment of the present invention.

5 is a schematic configuration diagram of a reference potential selection circuit of a power supply for a light emitting display device according to an embodiment of the present invention.

FIG. 6 is a diagram illustrating classification of various reference potentials of a power supply for a light emitting display device according to an embodiment of the present disclosure according to a voltage value level.

7 is a view showing a power supply for a light emitting display device having a reference potential stabilization circuit according to an embodiment of the present invention.

8A and 8B illustrate a reference potential stabilization circuit of a power supply for a light emitting display device implemented with an LDO regulator according to a specific embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for a light emitting display device, and more particularly, to a power supply for a light emitting display device having a reference potential selection circuit for providing a stable data voltage to a data driver of the light emitting display device.

An organic electroluminescence (EL) display device is a device for displaying an image by controlling an amount of current flowing through these organic materials by dividing an organic material emitting light when the current flows into pixels in a matrix form. Such an organic EL display device is expected to be a next generation display device due to advantages such as low voltage driving, light weight, wide viewing angle, and high speed response.

1 is a diagram showing the light emission principle of organic EL, respectively.

In general, an organic EL display device is a display device for electrically exciting a fluorescent organic compound to emit light, and is capable of displaying an image by driving voltage or current by driving N × M organic light emitting cells. As shown in FIG. 1, the organic light emitting cell structure has a structure of an indium tin oxide (ITO) pixel electrode, an organic thin film, and a metal layer, and the organic thin film has a good balance between electrons and holes to improve light emission efficiency. In order to achieve this, a multi-layered structure including an emitting layer (EML), an electron transport layer (ETL), and a hole transport layer (HTL) is formed, and a separate electron injection layer (EIL) is used. ) And a hole injecting layer (HIL).

As such a method of driving the organic light emitting cell, there are a simple matrix method and an active matrix method using a TFT. In the simple matrix method, the anode and the cathode are orthogonal and the line is selected and driven, whereas the active driving method is a driving method in which a TFT and a capacitor are connected to respective pixel electrodes to maintain a voltage by capacitor capacitance.

2 is a diagram illustrating a pixel circuit of a general organic EL.

As shown in Fig. 2, the pixel circuit includes an organic EL element OLED, two transistors SM and DM and a capacitor Cst. For example, the two transistors SM and DM may be formed as PMOS transistors.

The driving transistor DM has a source connected to the power supply voltage VDD, and a capacitor Cst connected between the gate and the source. The capacitor Cst maintains the gate-source voltage of the driving transistor DM for a predetermined period, and the driving transistor DM corresponds to a voltage held by the capacitor Cst, that is, a voltage between the gate and the source. Output the current. The switching transistor SM transfers the data signal from the data line Dm to the driving transistor DM in response to the selection signal from the current scan line Sn.

The organic EL element OLED has a cathode connected to a reference voltage Vss and emits light corresponding to a current applied through the driving transistor DM. Here, the power supply Vss connected to the cathode of the organic EL element OLED is a voltage having a lower level than the power supply VDD, and a ground voltage or the like may be used.

On the other hand, the data voltage of the organic EL display generates a data voltage by a DC / DC converter (mainly using a charge pump method) inside the data driver integrated circuit using an external power supply, which is the luminance of the display panel. This affects Brightness and Contrast. At this time, when the voltage of the external power supply or noise occurs, the data voltage is shaken, thereby affecting the brightness or contrast of the panel.

An object of the present invention for solving the above problems is to provide a power supply device for a light emitting display device having a reference potential stabilization circuit that can selectively supply a stable reference potential to the data driver integrated circuit even when the external power source fluctuates. It is for.

As a means for achieving the above object, the power supply for a light emitting display device according to the present invention,

A power supply device for supplying power to a data driver of a light emitting display device,

An external reference potential supply for supplying an external reference potential (VCIRex);

A reference potential generator which converts the external power into a stabilized DC reference potential VCIR when the voltage of the external power Vci input from the outside changes;

A reference potential selection unit for selecting and outputting any one reference potential input from the external reference potential supply unit or the reference potential generation unit; And

A voltage converter configured to convert the stabilized reference potential VCIR ′ output from the reference potential selector into a plurality of internal DC power supplies used in the driver, respectively.

Characterized in that it comprises a.

The apparatus may further include a controller configured to directly use the stabilized reference potential output from the reference potential selector or to distribute the stabilized reference potential to be converted into a plurality of internal DC power sources used in the data driver. Can be.

Here, the power supply determination unit for determining the voltage variation of the external power supply may further include.

Here, the reference potential generator stabilizes the external power input from the outside using an operational amplifier (OP-AMP), and the operational amplifier (OP-AMP) adjusts the data on / off voltage level input to the data driver. It is characterized by outputting one fixed output voltage by adjusting its potential voltage to be determined.

Here, the reference potential generator stabilizes the external power using a low voltage drop (LDO) regulator, and the low voltage drop (LDO) regulator inputs a voltage distributed by resistors connected internally to its output terminal from the outside. Compared to the external power source is characterized in that for outputting a fixed output voltage.

On the other hand, as another means for achieving the above object, the light emitting display device according to the present invention,

A light emitting display device comprising: a plurality of data lines transferring a data voltage corresponding to an image signal, a plurality of scanning lines transferring a selection signal, and a plurality of pixel circuits electrically connected to the scanning lines and the data lines,

a scan driver for sequentially applying a selection signal to each of the n scan lines;

a data driver which applies data voltages corresponding to image signals to the m data lines;

A panel controller which controls an R, G, B signal, a clock signal, and vertical and horizontal synchronization signals and sequentially provides the scan driver and the data driver;

Select the external reference potential (VCIRex) or the stabilized DC reference potential (VCIR) by receiving an external reference potential (VCIRex) or converting an external power source (Vci) input from the outside into a stabilized DC reference potential (VCIR). A power supply device for converting the selected reference potential into a plurality of internal DC power sources used in the data driver; And

A display panel for displaying an image by driving n × m light emitting cells by the signals provided by the scan driver and the data driver, and by the power provided by the power supply device.

Characterized in that it comprises a.

According to the present invention, by providing the data voltage of the driving unit IC of the organic EL light emitting display selectively among the stabilized reference potential and the external reference potential, it is possible to prevent the unevenness of the luminance of the organic EL light emitting display apparatus.

Hereinafter, the configuration and operation of a power supply for a light emitting display device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a view showing an organic EL display panel using an active driving method using a TFT according to an embodiment of the present invention.

Referring to FIG. 3, the organic EL display device includes an organic EL display panel 600, a data driver 400, and a scan driver 500.

The organic EL display panel 600 includes m data lines D1, D2, ..., Dm extending in the column direction, n scan lines S1, S2, ..., Sn extending in the row direction, and n × m. Pixel circuits. The m data lines D1, D2, ..., Dm transfer data signals representing an image signal to the pixel circuits, and the n scan lines S1, S2, ..., Sn transfer respective selection signals to the pixel circuits. . Here, the pixel circuit is formed in one pixel region 610 defined by two neighboring data lines D1, D2,..., And Dm and two neighboring scan lines S1, S2,..., Sn.

The scan driver 400 sequentially applies selection signals to the n scan lines S1, S2,..., And Sn, and the data driver 500 images the m data lines D1, D2,..., And Dm. The data voltage corresponding to the signal is applied.

In addition, the scan driver 400 and / or the data driver 500 may be electrically connected to the organic EL display panel 600, or a tape carrier adhered to and electrically connected to the organic EL display panel 600. The package may be mounted in a chip carrier package (TCP). Alternatively, the display panel 600 may be attached to a flexible printed circuit (FPC) or a film that is adhered to and electrically connected to the display panel 600 in the form of a chip.

In addition, the scan driver 400 and / or the data driver 500 may be directly mounted on the glass substrate of the organic EL display panel 600, or may be formed of the same layers as the scan line, the data line, and the thin film transistor on the glass substrate. It may be replaced with the driving circuit formed or may be directly mounted.

4 is a schematic block diagram of an organic EL display device according to an embodiment of the present invention.

Referring to FIG. 4, the organic EL display device may include a video controller 100, a panel controller 200, a power module 300, a scan driver 400, a data driver 500, and an organic EL panel 600. The various signals passing through the analog interface and the digital interface are provided to the organic EL panel 600 in the column and column directions by the scan driver 440 and the data driver 500, respectively.

Specifically, various analog signals such as R, G, B signals, and synchronization signals are input to the video controller 100 and then converted into digital signals, and the panel controller 200 controls them to sequentially scan the driver 400. And the data driver 500, the organic EL panel 600 is provided by the scan driver 400 and the data driver 500, and the power supply device 400. An n × m organic light emitting cell is driven by voltage or current by a power supply to represent an image.

5 is a schematic configuration diagram of a reference potential selection circuit of a power supply for a light emitting display device according to an embodiment of the present invention.

Referring to FIG. 5, a reference potential selection circuit of a power supply for a light emitting display device according to an exemplary embodiment of the present invention includes an external reference potential supply unit 330, a reference potential generation unit 310, and a reference potential selection unit 320. The external power determining unit 340 and the control unit 350 may be included.

The external reference potential supply unit 330 supplies an external reference potential VCIRex.

When the voltage of the external power source Vci input from the outside fluctuates, that is, when the fluctuation of the external power affects stably supplying a plurality of internal power sources, the reference potential generator 310 supplies the external power source. The output is converted into a stabilized DC reference potential (VCIR ').

The reference potential generating unit 310 is fixed to the external power applied from the outside having a voltage range of 2.5V to 3.3V to 2.0V and outputs.

In detail, the reference potential generator 310 converts the external power Vci input from the outside into a stabilized DC reference potential VCIR ′ in the power supply device for supplying power to the data driver of the light emitting display device. Done. Here, the external power input Vci input from the outside is an external power input voltage input through a battery.

In this case, the reference potential generator 310 may stabilize an external power input from the outside by using an operational amplifier (OP-AMP), and the operational amplifier (OP-AMP) may receive data input to the data driver. It adjusts its potential voltage to determine the on / off voltage level and outputs one fixed output voltage.

In addition, the reference potential generator 310 may stabilize the reference potential using a low drop out (LDO) regulator, and the low voltage drop (LDO) regulator internally at its output terminal. The output voltage fixed as one is output by comparing the voltage distributed by the connected resistors with the external power input from the outside. In general, the LDO voltage regulator may be formed of a bipolar junction transistor (BJT) or a field effect transistor (FET), which will be described later with reference to FIGS. 8A and 8B.

In addition, the reference potential selection unit 320 selects and outputs any one reference potential input from the external reference potential supply unit 330 or the reference potential generation unit 310.

In addition, the external power determination unit 340 determines the voltage fluctuation state of the external power. For example, when the address of the external reference potential determination signal VCIR_EX is 0, an internal reference potential generation mode is executed to generate a stable reference potential VCIR from the external power source Vci. If the address of the signal representing the determination signal VCIR_EX is 1, the external power supply is adjusted to be used as the reference potential VCIR, and eventually output to the reference potential VCIR 'selected by the reference potential selection unit 320. do.

In addition, the control unit 350 may directly use the stabilized reference potential or distribute the stabilized reference potential to be converted into a plurality of internal DC power sources used in the driving unit. In this case, the controller 350 provides the stabilized reference potential VCIR 'to the DC / DC converter DC 360 that provides a plurality of internal power supply voltages in the -14V to 14V voltage range. In practice, the control unit 350 may distribute the stabilized reference potential VCIR 'by a simple wiring connection, or may be distributed to various internal circuits requiring the stabilized reference potential VCIR' according to a predetermined instruction. You may. Alternatively, the controller 350 may not be separately designed, but may be implemented together with the DC / DC converter 360.

Therefore, in the embodiment of the present invention, by designing a voltage stabilization circuit, for example, an operational amplifier (OP-AMP) or low voltage drop (LDO) regulator for applying a stable data voltage to the data driver integrated circuit even if the external power supply fluctuates As a result, the output voltage of the stabilization circuit is used as a reference voltage. According to this structure, the data voltage is compensated by using a stabilized power supply for the fluctuation of the external power source, thereby preventing the luminance fluctuation due to the fluctuation of the data voltage. do.

6 is a diagram illustrating the division of various reference potentials of a power supply for a light emitting display device according to an exemplary embodiment of the present disclosure according to a voltage value level.

Referring to FIG. 6, the external power source 410 is composed of Vci of 2.5 to 3.3V, where Vci of 2.5 to 3.3V is a voltage input from a battery. That is, the Vci of 2.5 to 3.3V is converted into VCIR 'of 2.0V through the stabilization circuit according to the embodiment of the present invention, and then power is supplied to each of the internal circuits of the light emitting display device using the VCIR' of 2.0V as the reference potential. Will be supplied. As shown, the output 430 of the DC / DC converter can be divided according to each use from -14 to + 14V.

7 is a diagram illustrating a power supply device for a light emitting display device having a reference potential selection circuit according to a specific embodiment of the present invention.

Referring to FIG. 7, a power supply device 300 for a light emitting display device having a reference potential stabilization circuit according to a specific embodiment of the present invention may include a reference potential generator 310, a reference potential selector 320, and a control. It includes a voltage stabilization circuit 301 consisting of a circuit 350, and also includes first and second step-up circuits 360a and 360b which are DC / DC converters. It may also include a VdOUT output amplifier 370 required when using VdOUT.

As illustrated, the reference potential generator 310 converts the external power source into a stabilized DC reference potential (VCIR) when the voltage of the external power source Vci input from the outside changes, and selects the reference potential. The unit 320 selects one reference potential input from the external reference potential supply unit or the reference potential generator 310 to output VCIR '. Here, since the reference potential generator 310, the reference potential selector 320, and the control circuit 350 are the same as those described with reference to FIG. 5, a detailed description thereof will be omitted.

In addition, the external power source Vci is an external potential input from a battery, and is set to a predetermined voltage through a zener diode, respectively, and has a voltage range of 2.5 V to 3.3 V as described above. The quality of the external power supplied can be degraded. In this case, the reference potential output at a fixed voltage value through the reference potential stabilization circuit should be used.

In addition, the first and second step-up circuits 360a and 360b, which are DC / DC converters, are for converting to various internal power sources as shown in FIG. 6, respectively, and are provided in a plurality of -14V to 14V voltage ranges. It will provide an internal supply voltage.

8A and 8B are views illustrating a reference potential stabilization circuit of a power supply for a light emitting display device implemented with an LDO regulator according to a specific embodiment of the present invention.

FIG. 8A is a diagram schematically illustrating a reference potential stabilization circuit including a general LDO regulator 310, in which the low voltage drop (LDO) regulator inputs a voltage distributed from the outside by resistors connected internally to its output terminal. Compared to an external power supply, a single fixed output voltage is output. Where Cin represents an input capacitor and CL represents an output capacitor.

8B is an internal configuration diagram of the LDO regulator 711. The on / off controller 311, an error amplifier 312, a current limiter 313, a reference potential generator 314, Two series resistors R1 and R2 and a PMOS transistor Q1 may be included. That is, the output voltage is fixed by comparing the voltage distributed by the resistors R1 and R2 internally connected to its output terminal with an external power source. Here, Vin denotes an input signal, Vout denotes an output signal, Vss denotes a ground voltage, and CE denotes an enable signal for controlling on / off of the output voltage. It will be apparent to those skilled in the art that the LDO regulator 310 is not limited to the configuration shown in FIG. 8B and can be variously designed, that is, an LDO having various configurations different from those of FIG. 8B may be used.

As a result, according to the exemplary embodiment of the present invention, by providing a stable voltage inside the data driver of the light emitting display device, it is possible to prevent nonuniformity such as luminance due to the change of the data voltage.

While the invention has been shown and described in connection with specific embodiments thereof, it will be appreciated that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the claims. Anyone who owns it can easily find out.

According to the present invention, by selectively providing a stable voltage among the stabilized reference potential and the external reference potential inside the data driver of the light emitting display device, it is possible to prevent nonuniformity such as luminance due to a change in the data voltage.

Claims (8)

A power supply device for supplying power to a data driver of a light emitting display device, An external reference potential supply for supplying an external reference potential (VCIRex); A reference potential generator which converts the external power into a stabilized DC reference potential VCIR when the voltage of the external power Vci input from the outside changes; A reference potential selection unit for selecting and outputting any one reference potential input from the external reference potential supply unit or the reference potential generation unit; And A voltage converter configured to convert the stabilized reference potential VCIR ′ output from the reference potential selector into a plurality of internal DC power supplies used in the driver, respectively. Power supply for a light emitting display device comprising a. The method of claim 1, A light emitting display further includes a control unit for directly using the stabilized reference potential output from the reference potential selecting unit or distributing the stabilized reference potential to be converted into a plurality of internal DC power sources used in the data driver. Power supply for the device. The method of claim 1, And an external power determination unit for determining a voltage variation of the external power supply. The method of claim 1, And the reference potential generator is configured to stabilize an external power input from the outside using an operational amplifier (OP-AMP). The method of claim 4, wherein The operational amplifier (OP-AMP) outputs a single fixed output voltage by adjusting its own potential voltage for determining a data on / off voltage level input to the data driver. . The method of claim 1, And the reference potential generator is configured to stabilize the external power by using a low voltage drop (LDO) regulator. The method of claim 6, The low voltage drop (LDO) regulator outputs a fixed output voltage by comparing the voltage distributed by resistors internally connected to its output terminal with an external power source input from the outside. Feeding device. A light emitting display device comprising: a plurality of data lines transferring a data voltage corresponding to an image signal, a plurality of scanning lines transferring a selection signal, and a plurality of pixel circuits electrically connected to the scanning lines and the data lines, a scan driver for sequentially applying a selection signal to each of the n scan lines; a data driver which applies data voltages corresponding to image signals to the m data lines; A panel controller which controls an R, G, B signal, a clock signal, and vertical and horizontal synchronization signals and sequentially provides the scan driver and the data driver; Select the external reference potential (VCIRex) or the stabilized DC reference potential (VCIR) by receiving an external reference potential (VCIRex) or converting an external power source (Vci) input from the outside into a stabilized DC reference potential (VCIR). A power supply device for converting the selected reference potential into a plurality of internal DC power sources used in the data driver; And A display panel for displaying an image by driving n × m light emitting cells by the signals provided by the scan driver and the data driver, and by the power provided by the power supply device. Light emitting display device comprising a.

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