KR20060124487A - Electron emission display and control method of the same - Google Patents

Abstract

An electron emission display and a control method thereof are provided to secure a constant current value, by making a pixel unit display a predetermined image by controlling the input video data in applying a predetermined signal, and measuring and compensating the current flowing in the pixel unit which is displaying the image. An electron emission display includes a pixel unit(100) having plural scan lines(S1~Sn) and plural data lines(D1~Dm) and anode electrodes(Anode) formed over the entire region; a scan driving unit(200) successively transmitting a scan signal to the scan lines; a data driving unit(300) applying the data signal to plural data lines; a power supply unit(600) applying power to the scan and data driving units; a current measuring unit(400) measuring the current flowing in the anode electrodes; and a control unit(500) for generating a control signal by comparing the current measured in the current measuring unit with a pre-set reference current value, when the pixel unit displays a predetermined image by receiving a predetermined signal, and controlling the power supply unit by the control signal.

Description

ELECTRON EMISSION DISPLAY AND CONTROL METHOD OF THE SAME

1 is a diagram illustrating a structure of a conventional electron emission display device.

2 is a diagram illustrating an example of an electron emission display device according to an exemplary embodiment.

3 is a diagram illustrating an example of a controller employed in the electron emission display of FIG. 2.

4 is a view showing an example of an electron emission element employed in the electron emission display device according to the present invention.

5 is a flowchart illustrating an operation of an electron emission display device according to an exemplary embodiment.

6 is a diagram illustrating an example of a data driver employed in an electron emission display device according to the present invention.

FIG. 7A illustrates a change in luminance of a pixel unit according to driving of the conventional electron emission display. FIG. 7B illustrates a change in luminance of a pixel unit according to the driving of the electron emission display.

*** Description of the main symbols in the drawings ***

100: pixel portion 63, 400: current measuring portion

200: scan driver 500: comparator

300: data driver 600: reference current setting unit

700: correction unit

The present invention relates to an electron emission display device and a control method thereof. More particularly, the present invention relates to an electron emission display device and a method of controlling the same, which display a predetermined image when a specific signal is applied and measure and compensate a current flowing therein. will be.

In general, a flat panel display (FPD) is a device for manufacturing a container in a vacuum state by placing a sidewall between two substrates facing each other, and placing a suitable material inside the container to display a desired screen. The importance is increasing with the development of multimedia. In response to this, various flat panel displays, such as liquid crystal displays (LCDs), plasma display panels (PDPs), electron emission displays, and the like, have been developed and put into practical use.

In particular, the electron-emitting display device can be realized as a flat panel display having low power consumption without distortion of the image while maintaining excellent characteristics of the cathode ray tube (CRT) by using a phenomenon in which the phosphor emits light by an electron beam like the cathode ray tube (CRT). It is likely to be attracting attention as a next-generation display that has great potential and satisfactory in terms of viewing angle, high-speed response, high brightness, high definition, and thinness.

The electron emission display device has a structure of a triode tube having a cathode, an anode, and a gate electrode. Specifically, a cathode electrode generally used as a scan electrode is formed on a substrate, and an insulating layer having holes on the cathode electrode and a gate electrode generally used as a data electrode are stacked. An emitter, which is an electron emission source, is formed in the hole and contacts the cathode electrode.

The electron emission display device configured as described above concentrates a high electric field on an emitter and emits electrons by a quantum mechanical tunnel effect, and electrons emitted from the emitter are applied by a voltage applied between the cathode electrode and the anode electrode. By accelerating and colliding with the RGB fluorescent layer formed on the anode, the phosphor is emitted to represent an image. As the emitted electrons collide with the fluorescent layer and the phosphor emits light, the brightness of the displayed image is changed according to the input video data value.

1 illustrates a structure of a conventional light emitting display device.

Referring to FIG. 1, a conventional light emitting display device includes a pixel unit 10, a scan driver 20, a data driver 30, and a power supply 40.

The pixel portion 10 includes n scan lines S1, S2,... Sn, m data lines D1, D2, ... Dm, and an anode electrode ANODE, and the scan lines S1, S2, Sn is formed in the region where the data lines D1, D2, ... Dm cross each other. The anode ANODE may be formed over the entire region of the pixel portion 10, and may be formed in a plurality of stripe shapes formed in the row direction similarly to the scan lines S1, S2,... Similar to the data lines D1, D2, ... Dm, they may be formed in a plurality of stripes formed in the column direction, or may be formed in a mesh form. In addition, any one of the scan lines S1, S2, ... Sn and the data lines D1, D2, ... Dm is used as the cathode electrode, and the other one is used as the gate electrode.

The scan driver 20 sequentially applies a scan signal to the plurality of scan lines S1, S2, ... Sn.

The data driver 30 applies a data signal corresponding to the input video data DATA to the plurality of data lines D1, D2, ... Dm.

The power supply 40 applies the first power source V1 and the second power source V2 to the data driver 30, and applies the third power source V3 and the fourth power source V4 to the scan driver 20. do.

In the conventional electron emission display device as described above, as the driving time elapses, the function of the carbon nanotube (CNT) used as an emitter decreases, thereby deteriorating the electron emission device, and thus the emission current flowing through the anode electrode ANODE. The size of becomes small. Therefore, a problem arises in that an image of a desired gradation cannot be displayed.

Accordingly, an object of the present invention is to solve the above-described problem, and an object of the present invention is to allow a pixel portion to display a predetermined image when a specific signal is applied, and measure the current flowing in the pixel portion when the predetermined image is displayed. It is to compensate.

As a technical means for achieving the above object, one side of the present invention is a pixel portion in which a plurality of scan lines and a plurality of data lines are formed to cross each other, and an anode electrode is formed over the entire region, and sequentially in the plurality of scan lines. A scan driver for applying a scan signal to the data signal, and a data driver for applying a data signal to the plurality of data lines; And a power supply unit for supplying power to the scan driver and the data driver, a current measuring unit for measuring a current flowing through the anode electrode, and a pixel unit receiving a predetermined signal to display a predetermined image. The present invention provides an electron emission display device that compares the measured current with a preset reference current value, generates a control signal corresponding thereto, and controls the power supply unit by the generated control signal.

According to another aspect of the present invention, (a) applying a predetermined signal to a power supply, and adjusting the pixel unit to display a predetermined image when the predetermined signal is applied, (b) when the predetermined image is displayed, Measuring a current flowing in the pixel portion, (c) comparing the current measured in the step (b) with a preset reference current, and (d) compensating the measured current by the reference current. To provide an electron emission display device control method.

Hereinafter, the present invention will be described in detail with reference to FIGS. 2 to 6, which are attached to the preferred embodiments, which can be easily implemented by those skilled in the art.

2 is a diagram illustrating an example of an electron emission display device according to an exemplary embodiment of the present invention.

Referring to FIG. 2, an electron emission display device according to the present invention includes a pixel unit 100, a scan driver 200, a data driver 300, a current measuring unit 400, a controller 500, and a power supply unit ( 600).

The pixel unit 100 includes n scan lines S1, S2,... Sn, m data lines D1, D2, ... Dm, and an anode electrode ANODE, and the scan lines S1, S2, Sn is formed in the region where the data lines D1, D2, ... Dm cross each other. The anode ANODE may be formed over the entire area of the pixel portion 100, and may be formed in a plurality of stripe shapes formed in the row direction similar to the scan lines S1, S2,... Similar to the data lines D1, D2, ... Dm, they may be formed in a plurality of stripes formed in the column direction, or may be formed in a mesh form. One of the scan lines S1, S2, ... Sn and the data lines D1, D2, ... Dm acts as a cathode electrode, and the other acts as a gate electrode.

The scan driver 200 sequentially applies a scan signal to the plurality of scan lines S1, S2, ... Sn.

The data driver 300 applies a data signal to the plurality of data lines D1, D2, ..., D m.

The current measuring unit 400 is connected to the anode electrode ANODE of the pixel unit 100 to measure the current flowing through the anode electrode ANODE when the pixel unit 100 displays a specific gray scale. In this case, the specific gradation may be a full white gradation or an arbitrarily set image gradation.

The controller 500 compares the current measured by the current measuring unit with a preset reference current and transmits a control signal corresponding thereto to the power supply unit 600.

The power supply unit 600 applies the first power source V1 and the second power source V2 to the data driver 300, and applies the third power source V3 and the fourth power source V4 to the scan driver 200. do. In addition, the power supply unit 800 adjusts the voltage applied between the scan driver 200 and the data driver 300, that is, the voltage between the cathode electrode and the gate electrode according to the control signal output from the controller 500. The current flowing on the anode electrode ANODE of the pixel portion 100 is corrected.

Video data input to the data driver 300 when a predetermined signal is applied to the above-mentioned electron emission display device, for example, a power supply signal, an interrupt signal, and an RS-232C communication signal, and the predetermined signal is applied. By adjusting DATA, the pixel unit 100 displays a predetermined image, for example, a full white gradation or a predetermined specific image. When the pixel unit 100 displays a predetermined image, the current flowing through the anode electrode of the pixel unit 100 is measured to compensate for this.

3 is a diagram illustrating an example of a controller employed in the electron emission display of FIG. 2.

Referring to FIG. 3, the control unit includes a reference voltage setting unit 510 and a comparison unit 520.

The reference current setting unit 510 sets a reference current to compensate for the current value measured from the current measuring unit 400. The reference current may be set in advance from the outside.

The comparator 520 compares the preset reference current from the reference current setting unit 510 with the current Ia measured by the current measuring unit 400 and outputs a control signal corresponding thereto.

4 is a view showing an example of an electron emission element employed in the electron emission display device according to the present invention.

Referring to FIG. 4, the electron emission device according to the present invention includes a back substrate 51, a cathode electrode 52, an insulating layer 53, a gate electrode 54, an emitter 55, and a front substrate 60. ), An anode electrode 61, a phosphor 62, and a current measuring unit 63.

The back substrate 51 may be a glass or silicon substrate, and when the emitter 55 is formed by back exposure using a CNT, that is, a carbon nanotube, a transparent substrate such as a glass substrate may be used.

The cathode electrode 52 may be formed in a stripe shape on the rear substrate. The cathode electrode 52 is supplied with a data signal or a scan signal applied from the data driver or the scan driver. The cathode electrode 52 may be a conductor and may be a transparent conductor such as indium tin oxide (ITO) for the same reason as the back substrate 51.

The insulating layer 53 is formed on the rear substrate 51 and the cathode electrode 52, and electrically insulates the cathode electrode 52 and the gate electrode 54. The insulating layer 53 may be made of an insulating material such as PbO and SiO ₂ mixed glass.

The gate electrode 54 is disposed on the insulating layer 53 in a predetermined shape, for example, in a direction crossing the cathode electrode 52 on a stripe, and each data signal or scan applied from the data driver or the scan driver. The signal is supplied.

The emitter 55 is electrically connected on the cathode electrode 52 and includes carbon nanotubes; Nanotubes by graphite, diamond, diamond-like carbon or a combination thereof; Or nanowires of Si or SiC.

The front substrate 60 may be made of a transparent material so that the light emitted from the phosphor 62 may emit well to the outside.

The anode electrode 61 is applied with a high-voltage positive voltage to accelerate the electrons e emitted from the emitter 55 better, thereby accelerating the electrons e toward the phosphor 62. In addition, the anode electrode 61 may be made of a transparent material such as an ITO electrode so that light emitted from the phosphor 62 is well emitted to the outside.

The phosphor 62 emits light by the collision of electrons e emitted from the emitter 55 and is selectively disposed on the anode electrode 61 at arbitrary intervals.

The current measuring unit 63 has a form in which a series resistor Rs is connected between the anode electrode 61 and the ground power supply GND. When electrons emitted from the electron emission device are accelerated at the anode electrode ANODE and collide with the phosphor 62 to emit light, the emission current flows through the anode electrode ANODE, and the current is detected using the series resistance Rs. can do.

5 is a flowchart illustrating an operation of an electron emission display device according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the electron emission display device according to the present invention operates through the first step ST100 to the sixth step ST600.

The first step ST100 is to apply a predetermined signal to the electron emission display device. In this case, the predetermined signal may be a signal to which power is applied, an arbitrarily set interrupt signal, or a signal due to RS-232C communication.

The second step ST200 is a step of adjusting the video data DATA so that the pixel unit 100 displays a predetermined image at a time when a predetermined signal of the first step ST100 is applied. In this case, the predetermined image displays an image displaying full white gradation or a predetermined image.

The third step ST300 is a step of calling a preset reference current from the outside.

The fourth step ST400 is a step of measuring a current flowing through the anode electrode ANODE of the pixel unit 100 in the first step ST100 and the second step ST200. In this case, as an example of a method of measuring current, a series resistor may be connected between the anode electrode ANODE and the ground power supply GND, and the voltage across the series resistor may be measured.

The fifth step ST500 is a step of comparing the current measured in the fourth step ST400 with the reference current called in the third step ST300.

The sixth step ST600 is to increase the voltage applied between the cathode electrode and the gate electrode until the current measured according to the result value of the fifth step ST500 becomes the reference current value.

6 is a diagram illustrating an example of a data driver employed in an electron emission display device according to the present invention.

Referring to FIG. 6, the data driver includes a serial-parallel converter 310, a pulse width modulator 320, and a level adjuster 330.

The serial-parallel converter 310 converts sequentially input video data DATA into parallel video data and outputs the parallel video data. In this case, the input video data DATA may be adjusted to display a specific image, for example, an image corresponding to the full white gray level, at an arbitrary time point.

The pulse width modulator 320 outputs a data signal obtained by pulse width modulating the parallel video data DATA output from the serial-parallel change unit 310. In this case, when the parallel video data is high grayscale data, the data signal output from the pulse width modulator 320 has a wide pulse width, and when the parallel video data is low grayscale data, the pulse width modulator The data signal output at 320 has a narrow pulse width.

The level adjuster 330 adjusts the voltage level of the data signal output from the pulse width modulator 320 according to the first and second power supplies V1 and V2 applied from the power supply 800, thereby adjusting the data line ( D1, D2, ... Dm) function to output. More specifically, the high level voltage of the data signal output from the level adjuster 330 corresponds to the voltage of the first power source V1, and the low level voltage corresponds to the voltage of the second power source V2. Therefore, as the voltage of the first power source V1 and / or the voltage of the second power source V2 is changed, the high level voltage and / or the low level voltage of the data signal is changed. If the data lines D1, D2, ... Dm are used as cathodes, the electron emitting element emits electrons when the data signal has a low level voltage, that is, the voltage of the second power source V2, The power supply can change the voltage difference between the gate electrode and the cathode electrode at the time of electron emission by changing the voltage level of the second power supply V2. In this case, the voltage level of the first power source V1 may be fixed or may be changed as the voltage level of the second power source V2 is changed. Further, if the data lines D1, D2, ... Dm are used as the gate electrodes, the electron-emitting device emits electrons when the data signal has a high level voltage, that is, the voltage of the first power supply VS1. Therefore, the power supply may change the voltage difference between the gate electrode and the cathode electrode at the time of electron emission by changing the voltage level of the first power supply VS1. In this case, the voltage level of the second power supply VS2 may be fixed or may be changed as the voltage level of the first power supply VS1 is changed.

FIG. 7A illustrates a change in luminance of a pixel unit according to driving of the conventional electron emission display. FIG. 7B illustrates a change in luminance of a pixel unit according to the driving of the electron emission display.

Referring to FIGS. 7A and 7B, it can be seen that in the conventional electron emission display device before correction, the luminance of the pixel portion gradually decreases as the driving time elapses. This is due to the deterioration of the electron emission display due to the reduced function of the emitter. On the other hand, after the correction, that is, in the electron emission display device according to the present invention, the luminance of the pixel portion decreases according to the elapsed driving time, but the luminance remains constant for a predetermined period of time.

Although the technical spirit of the present invention has been described in detail according to the above preferred embodiment, it should be noted that the above embodiment is for the purpose of description and not of limitation. In addition, it will be understood by those skilled in the art that various modifications are possible within the scope of the technical idea of the present invention.

According to an electron emission display device and a control method thereof according to the present invention, when a predetermined signal is applied, the pixel unit displays a predetermined image by adjusting input video data, and at this time, by measuring and correcting current flowing through the pixel unit, The current value can be obtained. In addition, by displaying the full white gray level in a predetermined image, the influence of the error of the current value measurement can be minimized, and the lifespan of the electron emission display device can be increased by the current compensation operation described above.

Claims (14)

A pixel portion in which a plurality of scan lines and a plurality of data lines are formed to cross each other, and an anode electrode is formed over the entire region; A scan driver which sequentially applies a scan signal to the plurality of scan lines; A data driver for applying a data signal to the plurality of data lines; And A power supply unit applying power to the scan driver and the data driver; A current measuring unit measuring a current flowing through the anode electrode; And When the pixel unit receives a predetermined signal to display a predetermined image, the current measured by the current measuring unit is compared with a preset reference current value to generate a control signal corresponding thereto, and to generate the control signal. And an electron emission display device controlling the power supply unit. The method of claim 1, The control unit includes a reference current setting unit for setting a reference current to compensate for the current measured by the current measuring unit; And And a comparator for comparing the measured current with the reference current and outputting the control signal corresponding thereto. The method of claim 1, And the data line is connected to any one of a cathode electrode and a gate electrode, and the other of the cathode electrode and the gate electrode is connected to the scan line. The method of claim 3, wherein And the power supply unit compensates the measured current by adjusting a level of a voltage applied between the cathode electrode and the gate electrode. The method of claim 1, The predetermined signal is an electron emission display device which is a signal transmitted at a time of power-on or a predetermined signal. The method of claim 1, And the predetermined image is an image when the pixel portion displays a full white gray level, or a preset image. The method of claim 1, And the current measuring unit connects a series resistor between the anode electrode and a ground power source. (a) applying a predetermined signal to a power supply unit and adjusting the pixel unit to display a predetermined image when the predetermined signal is applied; measuring current flowing in the pixel portion when the predetermined image is displayed; (c) comparing the current measured in step (b) with a preset reference current; (d) compensating for the measured current by the reference current. The method of claim 8, Wherein (a) is a time when the power is turned on, or a time when a predetermined signal is applied. The method of claim 9, And applying the predetermined signal using an RS-232C communication method. The method of claim 9, And said predetermined signal is an interrupt signal. The method of claim 8, In the step (b), the pixel unit displays a full white gray scale or displays a predetermined image. The method of claim 10, And (c) is a step of connecting a series resistor between an anode electrode and a ground power supply and measuring a voltage across the series resistor when the operation of step (b) occurs. The method of claim 8, And (e) adjusting the magnitude of the voltage applied between the cathode electrode and the gate electrode to compensate for the measured current.

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