KR20070073342A - Driving device for electron emission device and the method thereof - Google Patents

Abstract

An apparatus and a method for driving an electron emission device are provided to prevent degradation of image quality by stably adjusting a voltage between a gate electrode and a cathode electrode. An apparatus for driving an electron emission device includes a pixel unit, a data driver, a scan driver, a controller, and a power supply unit. The pixel unit includes plural electron emission devices, which are formed on cross sections of plural data and scan lines. The data driver supplies a data signal, which corresponds to image data, to the data lines. The scan driver sequentially supplies a scan signal to the scan lines. The controller outputs a reference voltage corresponding to the image level of the image data. The power supply unit supplies a source voltage, which has a voltage level corresponding to the reference voltage, to at least one of the data and scan drivers. The power supply unit supplies a brightness level source voltage(V2) after stabilizing a gate driving source voltage(V1).

Description

Driving device for electron emitting device and driving method thereof {DRIVING DEVICE FOR ELECTRON EMISSION DEVICE AND THE METHOD THEREOF}

1 is a view schematically showing a configuration of a conventional electron emission display device.

2 is a diagram illustrating a voltage application waveform for luminance control in a conventional power supply unit;

3 is a view schematically showing an example of the structure of an electron emission display device according to the present invention;

4 shows an example of a part of a pixel portion that can be employed in an electron emission display device according to the present invention;

5 illustrates an example of a power supply unit that may be employed in the electron emission display of FIG. 3.

6 illustrates an example of a controller that may be employed in the electron emission display of FIG. 3.

7 is a diagram illustrating a voltage applied by the DC / DC converter of FIG. 5.

8 is a diagram illustrating a voltage application waveform for luminance control according to the present invention.

<Description of main parts of drawing>

100 --- Pixel part 200 --- Data driver

300 --- Scan driver 400 --- Power supply

401 --- MICOM 402 --- DC / DC Converters

500 --- control unit

The present invention relates to a device for driving an electron-emitting device and a driving method thereof, and more particularly to an electron-emitting device that can be stably driven without deterioration in image quality in controlling a voltage between a gate electrode and a cathode electrode to be controlled for brightness control. A driving device and a driving method thereof are provided.

In general, a flat panel display (FPD) is a device for manufacturing a sealed container by standing a side wall between two substrates, and placing a suitable material inside the container to display a desired screen. Together, its importance is increasing. In response to this, various flat panel displays such as a liquid crystal display (LCD), a plasma panel (PDP), an electron emission display, and the like have been developed and put into practical use.

In particular, the electron-emitting display device can be implemented as a low-power flat-panel display without distorting the image while maintaining excellent characteristics of the cathode ray tube (CRT) by using phosphor emission by electron beams in the same way as the cathode ray tube (CRT). It is attracting attention as a next-generation display that is satisfactory in terms of high, viewing angle, high-speed response, high brightness, high definition, and thinness.

The electron emission display device has a structure of a triode 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 caused 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 luminance of the displayed image is changed according to the value of the input digital image signal. Specifically, the value of the digital video signal is composed of 8 bits of RGB data, respectively. That is, the value of the digital video signal may be 0 (00000000 ₍₂₎ ) to 255 (11111111 ₍₂₎ ), and thus 256 gray levels may be represented by 256 values. Luminance is expressed.

In order to adjust the luminance represented according to the value of the digital image signal, a pulse width modulation (PWM) method or a pulse modulation (PAM) method is generally used.

The PWM method modulates the pulse width of the driving waveform applied to the data electrode in accordance with the digital image signal input from the data electrode driver. 255 is input as the value of the digital image signal within the maximum available on-time. In this case, the pulse width is maximized to display the maximum luminance, and when 127 is input as the value of the digital video signal, the pulse width is 1/2 to decrease the luminance. On the other hand, in the PAM method, the pulse width is constant regardless of the input digital video signal, but the luminance is controlled by varying the pulse voltage level of the driving waveform applied to the data electrode, that is, the pulse size, according to the input digital video signal.

1 is a view schematically showing a configuration of a conventional electron emission display device. As illustrated, the electron emission display device includes a pixel unit 10, a data driver 20, a scan driver 30, a power supply 40, and a controller 50.

The pixel portion 10 includes n scan lines S1, S2,... Sn, m data lines D1, D2, ... Dm, and an anode electrode ANODE. Scan lines S1, S2, ... Sn and data lines D1, D2, ... Dm cross each other. The anode ANODE may be formed over the entire area of the pixel portion as shown in the figure, and although not shown in the figure, may be formed in a plurality of stripe shapes formed in the row direction similar to the scan lines. Similar to the data lines, a plurality of stripes may be formed in a column direction or may be formed in a mesh form.

Even when the anode electrode is formed in the form of a plurality of stripes or in the form of a mesh, generally the same voltage (Vanode) is applied to the entire anode electrode. The electron emission device including the cathode electrode, the gate electrode, and the anode electrode is formed in an area where the scan line and the data line cross each other, and either one of the scan line and the data line serves as a cathode, and the other of the scan line and the data line is a gate. It acts as an electrode.

The data driver 20 performs a function of applying a data signal corresponding to the input image data DATA to the data lines D1, D2,..., Dm. Here, the data driver of pulse width modulation (also referred to as PWM) will be described, but any data driver for adjusting the electron emission time of the electron emission device in response to the input image data is included.

The scan driver 30 sequentially applies a scan signal to the scan lines S1, S2,... Sn.

The power supply unit 40 applies a first power source Vg to the data driver 20, a second power source Vc to the scan driver 30, and a third power source Va to the anode electrode of the pixel unit. Is applied.

The controller 50 obtains an image level of the image data DATA, and then varies at least one of a voltage applied to the anode electrode, a voltage applied to the cathode electrode, and a voltage applied to the gate electrode corresponding to the obtained image level. It performs the function. Here, the image level is a concept corresponding to the brightness of the entire pixel portion 10. A high image level means that the pixel portion 10 is bright, and a low image level means that the pixel portion 10 is dark. Means that. The image level can be obtained by, for example, summing up image data DATA of one frame.

The controller 50 controls the power supply 40 to increase the anode voltage at the time of electron emission when the image level is low and to decrease the anode voltage at the time of electron emission when the image level is high. When the brightness is realized by controlling the anode voltage, not only the number of gray levels is reduced, but also the driving conditions such as the pulse width modulation method (PWM) or the amplitude modulation method (PAM) can be easily realized without changing the driving conditions.

In addition, the power supply 40 is controlled to increase the difference between the cathode voltage and the gate voltage. The controller 50 reduces the difference between the cathode voltage and the gate voltage at the time of electron emission when the image level is increased, and increases the difference between the cathode voltage and the gate voltage at the time of electron emission when the image level is decreased. ).

2 is a diagram illustrating a voltage application waveform for luminance control in a power supply unit according to the related art. As shown in the drawing, the power supply unit adjusts the cathode voltage and the gate voltage for brightness control, and the gate voltage is driven by being divided into a gate driving voltage and a control voltage. Here, the gate driving voltage is a basic voltage value V2 for gate driving regardless of luminance control, and the control voltage adjusts a width of the voltage V1 that varies according to an image input. At this time, by configuring the two voltages in series to implement a dynamic image.

However, the two voltages connected in series are driven at the same time when the power is turned on to cause instability of the panel and the power terminal due to overshoot.

SUMMARY OF THE INVENTION An object of the present invention is to provide a device for driving an electron-emitting device and a method of driving the same, which can be stably driven without deterioration in image quality in controlling the voltage between the gate electrode and the cathode electrode to be controlled for brightness control.

The driving device of the electron-emitting device according to the present invention to achieve the above object,

A pixel portion including a plurality of electron emission elements formed in an intersection region of the plurality of data lines and the plurality of scan lines; A data driver for applying a data signal corresponding to image data to the plurality of data lines; A scan driver for sequentially applying scan signals to the plurality of scan lines; A controller for outputting a reference voltage corresponding to an image level of the image data; And a power supply for applying power having a voltage level corresponding to the reference voltage to at least one of the data driver and the scan driver, wherein the power supply is configured in series with a driving power terminal and a luminance level power terminal. After stabilizing the voltage of the driving power supply stage, the characteristics of the luminance control power supply terminal are applied.

In addition, the driving method of the electron-emitting device according to the present invention in order to achieve the above object, the step of receiving a power supply signal from the outside and applying an anode driving voltage; Applying a cathode driving voltage after applying the anode driving power; Determining whether the anode driving voltage and the cathode driving voltage are applied with a reference voltage value; After determining whether the reference voltage value is applied, the method may include applying a gate driving voltage corresponding to a stabilization time point.

In particular, the gate driving voltage is characterized in that the gate driving power supply terminal V1 and the luminance level power supply terminal V2 are connected in series.

In particular, the gate driving voltage is characterized in that the voltage of the luminance level power supply terminal V2 is applied after the voltage stabilization time of the gate driving power supply terminal V1 is applied.

Here, in particular, the voltage of the luminance level power supply terminal V2 is applied by a delay signal while the stabilization time of the gate driving power supply terminal is reached.

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

3 is a view schematically showing an example of the structure of an electron emission display device according to the present invention. Referring to FIG. 3, the electron emission display device according to the present invention includes a pixel unit 100, a data driver 200, a scan driver 300, a power supply unit 400, and a controller 500.

The pixel unit 100 includes n scan lines S1, S2,... Sn, m data lines D1, D2, ... Dm, and an anode electrode ANODE, and scan lines S1, S2. , ... Sn) and a plurality of pixels are formed in a region where the data lines D1, D2, ... Dm cross each other. In this case, the anode electrode ANODE may be formed over the entire area of the pixel portion 100, and any one of the scan lines S1, S2,... Sn and the data lines D1, D2,... It may be used as a cathode electrode and the other one may be used as a gate electrode.

The data driver 200 applies a data signal corresponding to the input video data DATA to the plurality of data lines D1, D2,..., Dm.

The scan driver 300 sequentially applies a scan signal to the plurality of scan lines S1, S2,... Sn.

The power supply unit 400 includes a microcomputer 401 and a DC / DC converter 402, applies a first power source (Vg) to the data driver 200, and a second power source to the scan driver 300. A third power source Va is applied to Vc and the anode electrode of the pixel unit 100.

The controller 500 compensates for the degradation of the phosphor of the pixel unit by varying the voltage according to the driving time and / or the magnitude of the total video data input during one frame period.

Hereinafter, the sum of video data input to each of the plurality of pixels during one frame is called frame data.

In more detail, the lifetime information of the pixel according to the driving time and / or the lifetime information of the pixel according to the size of the frame data are stored, and the voltage level between the gate electrode and the cathode electrode is adjusted according to the stored information, or the anode electrode ANODE. The control signal to adjust the voltage level of the output.

4 is a diagram illustrating an example of a portion of a pixel portion that may be employed in the electron emission display device according to the present invention. As shown therein, the pixel unit 100 includes an electron emission substrate 120 and an image forming substrate 130. In addition, the electronic device may further include a spacer 140 that maintains a constant gap between the electron emission substrate 120 and the image forming substrate 130.

The electron emission substrate 120 is a substrate that emits electrons in response to the voltage between the cathode electrode 122 and the gate electrode 124. The back substrate 121, the cathode electrode 122, the insulating layer 123, and the gate are provided. The electrode 124 and the electron emission part 125 are provided.

The back substrate 121 may be, for example, a glass or silicon substrate. When the back substrate 121 is formed by back exposure using a carbon nanotube (CNT) paste as the electron emission unit 125, a transparent substrate such as a glass substrate is preferable. .

The cathode electrode 122 may be formed in a stripe shape on the rear substrate. The cathode electrode 122 is supplied with a data signal or a scan signal applied from the data driver or the scan driver. The cathode electrode 122 may be a conductor and may be a transparent conductor such as indium tin oxide (ITO), for the same reason as the back substrate 121.

The insulating layer 123 is formed on the back substrate 121 and the cathode electrode 122, and electrically insulates the cathode electrode 122 from the gate electrode 124. The insulating layer 123 may be made of an insulating material, for example, PbO and SiO ₂ mixed glass.

The gate electrode 124 is disposed on the insulating layer 123 in a predetermined shape, for example, in a direction crossing the cathode electrode 122 on a stripe, and each data signal or scan signal applied from the data driver or the scan driver. Is supplied. The gate electrode 124 is made of a metal having good conductivity, such as at least one conductive metal material selected from gold (Au), silver (Ag), platinum (Pt), aluminum (Al), chromium (Cr), and alloys thereof. Can be. The insulating layer 123 and the gate electrode 124 include at least one first opening 126 in the intersection region of the cathode electrode 122 and the gate electrode 124 so that the cathode electrode 122 is exposed.

The electron emission unit 125 is electrically connected to and positioned on the cathode electrode 122 exposed by the first opening 126, and includes a carbon nanotube; Nanotubes by graphite, diamond, diamond-like carbon or a combination thereof; Or a nanowire of Si or SiC.

The image forming substrate 130 is a substrate for forming an image by collision of electrons emitted from the electron emission substrate 120 to emit light. The image forming substrate 130 includes a front substrate 131, an anode electrode 132, a phosphor 133, and a light shielding film. 134 and a metal reflective film 135.

The front substrate 131 is preferably made of a transparent material such as glass so that light emitted from the phosphor 133 is transmitted to the outside.

The anode electrode 132 is preferably made of a transparent material such as an ITO electrode so that light emitted from the phosphor 133 is transmitted to the outside. The anode electrode 132 accelerates the electrons emitted from the electron emitting device even better. To this end, a high voltage positive voltage is applied to the anode electrode 132 to accelerate the electrons toward the phosphor 133.

The phosphor 133 emits light due to the collision of electrons emitted from the electron emission substrate 120, and is selectively disposed on the anode electrode 132 at random intervals. Examples of the G phosphor, that is, the phosphor that develops green color include, for example, ZnS: Cu, Zn ₂ SiO ₄ : Mn, ZnS: Cu + Zn ₂ SiO ₄ : Mn, Gd ₂ O ₂ S: Tb, Y ₃ Al ₅ O ₁₂ : Ce, ZnS: Cu, Al, Y ₂ O ₂ S: Tb, ZnO: Zn, ZnS: Cu, Al + In ₂ O ₃ , LaPO ₄ : Ce, Tb, BaO · 6Al ₂ O ₃ : Mn, (Zn, Cd) S: Ag, (Zn, Cd) S: Cu, Al, ZnS: Cu, Au, Al, Y ₃ (Al, Ga) ₂ O ₁₂ : Tb, Y ₂ SiO ₅ : Tb, or LaOCl: Tb Can be used. In addition, the B phosphor, i.e., a phosphor that develops blue color, may be, for example, ZnS: Ag, ZnS: Ag, Al, ZnS: Ag, Ga, Al, ZnS: Ag, Cu, Ga, Cl, ZnS: Ag + In ₂ O. _{3, Ca 2 B 5 O 9} Cl: Eu 2 +, (Sr, Ca, Ba, Mg) 10 (PO 4) 6 Cl 2: Eu 2 +, Sr 10 (PO 4) 6 C 2: Eu 2+, ^{_{BaMgAl 16 O 26: Eu 2 +}} , CoO, Al 2 O 3 Added ZnS: Ag, ZnS: Ag or Ga can be used. Further, the R phosphor, i.e., the phosphor emitting red color, may be, for example, Y ₂ O ₂ S: Eu, Zn ₃ (PO ₄ ) ₂ : Mn, Y ₂ O ₃ : Eu, YVO ₄ : Eu, (Y, Gd) BO ₃ : Eu, γ-Zn ₃ (PO ₄ ) ₂ : Mn, (ZnCd) S: Ag, (ZnCd) S: Ag + In ₂ O ₃ , or Fe ₂ O ₃ Added Y ₂ O ₂ S: Eu can be used.

The light shielding film 134 is disposed at random intervals between the phosphors 133 to absorb and block external light and prevent optical crosstalk, thereby improving contrast ratio.

The metal reflective film is formed on the phosphor 133 to better focus electrons emitted from the electron emission substrate 120, and reflects light emitted from the phosphor 133 to the front substrate 131 by collision of electrons. To improve reflection efficiency. On the other hand, if the metal reflecting film serves as an anode electrode, the formation of the anode electrode 132 is optional and may be an unnecessary component.

FIG. 5 is a diagram illustrating an example of a power supply unit that may be employed in the electron emission display of FIG. 3. As shown therein, the power supply unit 400 includes a microcomputer 401 and a DC / DC converter 402.

The microcomputer 401 receives the controlled image level from the controller 500 and outputs a voltage level corresponding thereto. That is, a function of generating a reference voltage Vref corresponding to the image level is performed.

More specifically, the microcomputer 401 adjusts the image level output from the controller 500 to a voltage level corresponding thereto, and when the image level is high, decreases the voltage, and when the image level is low, the microcomputer 401 outputs the voltage. Raised. Here, when the output voltage is adjusted to the cathode voltage level or the gate voltage level, when the image level is high, the cathode or gate voltage is lowered, and when the image level is low, the cathode or gate voltage is increased.

The DC / DC converter 402 measures a voltage applied to the data driver 200 and the scan driver 300, that is, a difference between the cathode electrode and the gate electrode according to the control signal output from the microcomputer 401. The luminance of the pixel unit 100 is compensated by adjusting the voltage applied to the anode or the anode.

FIG. 6 is a diagram illustrating an example of a controller that may be employed in the electron emission display of FIG. 3. As shown therein, the controller 500 includes a frame memory 501, a LUT 502, and an operation unit 503.

The frame memory 501 stores an input video signal and outputs data of one frame of the frame.

The look up table (LUT) 502 stores a data conversion index for each step by dividing the average value of the reference luminance level of the image signal data into detailed steps of light and dark of the screen according to the average value. Alternatively, the LUT 240 may not be provided separately, but may be implemented in logic in the calculator 503.

The calculator 503 determines an image level using the image data DATA of one frame. The more data corresponding to the high gray level is in the image data DATA of one frame, the higher the image level is, and the more the data corresponding to the lower gray level is included in the image data DATA of one frame, the lower the image level is.

For example, the calculator 503 may obtain an image level by using the sum of the image data DATA corresponding to one frame stored in the frame memory 501. More specifically, the calculator 503 may obtain the sum of the image data DATA corresponding to one frame, and then determine and output the upper 8 bits of the sum as the image level.

The average value calculated for the obtained predetermined frame is compared with the average value of the reference luminance level stored in the LUT 502. As the luminance level of the predetermined frame is large and small, it is determined whether to select one of the voltage applied to the anode electrode, the voltage applied to the cathode electrode, and the voltage applied to the gate electrode to adjust the corresponding voltage. do.

7 is a diagram illustrating a voltage applied by the DC / DC converter of FIG. 5. As shown in the drawing, the DC / DC converter 402 sequentially applies the anode driving voltage Va, the cathode driving voltage Vc, and the gate driving voltage Vg when the power supply of the driving device of the electron-emitting device is applied. Done. Here, the gate driving voltage Vg is applied in series with the gate driving power supply terminal V1 and the luminance level power supply terminal V2.

8 is a diagram illustrating a voltage application waveform for luminance control according to the present invention. As shown in FIG. 2, after the gate driving power supply terminal V1 and the brightness level power supply terminal V2 connected in series with the gate driving voltage Vg are determined, the stabilization time of the gate driving power supply terminal V1 is determined. The luminance level power supply terminal V2 is applied by the delay signal.

More specifically, when it is determined that the stabilization time is reached by first applying the gate driving power supply terminal V1 when the gate driving voltage Vg is applied, the luminance level power supply terminal V2 of the luminance level power supply terminal V2 is stabilized at the stabilization time. The voltage is applied. At this time, the voltage of the luminance level power supply terminal V2 is applied after the stabilization time is reached by the delay signal while the stabilization time is reached.

Therefore, it is possible to provide a dynamic image by stably applying the brightness control voltage when the power is applied.

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.

As described above, the driving device and the driving method of the electron-emitting device of the present invention can be stably driven without deteriorating the image quality in controlling the voltage between the gate electrode and the cathode electrode to be adjusted for the brightness control. .

Claims (10)

A pixel portion including a plurality of electron emission elements formed in an intersection region of the plurality of data lines and the plurality of scan lines; A data driver for applying a data signal corresponding to image data to the plurality of data lines; A scan driver for sequentially applying scan signals to the plurality of scan lines; A controller for outputting a reference voltage corresponding to an image level of the image data; A power supply unit configured to apply power having a voltage level corresponding to the reference voltage to at least one of the data driver and the scan driver, The power supply unit is configured in series with a driving power supply terminal and a brightness level power supply, the driving device of the electron-emitting device, characterized in that for applying the voltage of the brightness control power supply after the stabilization of the voltage of the driving power supply. The method of claim 1, And the control unit includes a frame memory, a look-up table, and a calculation unit. The method of claim 1, The power supply unit driving device of the electron-emitting device, characterized in that composed of a microcomputer and a DC / DC converter. The method of claim 3, wherein The DC / DC converter is a driving device of the electron-emitting device, characterized in that for sequentially applying the driving voltage, the cathode driving voltage and the gate driving voltage. The method of claim 4, wherein And the gate driving voltage is applied in series with the gate driving power supply terminal (V1) and the luminance level power supply terminal (V2). The method of claim 3, wherein And the luminance level power supply terminal (V2) is applied to the gate driving voltage by a delay signal after the stabilization time of the gate driving power supply terminal (V1) is determined. Receiving an external power supply signal and applying an anode driving voltage; Applying a cathode driving voltage after applying the anode driving power; Determining whether the anode driving voltage and the cathode driving voltage are applied with a reference voltage value; And applying a gate driving voltage corresponding to a stabilization time point after determining whether the reference voltage value is applied. The method of claim 7, wherein In the step of applying the gate driving voltage, the gate driving voltage is applied to the gate driving power supply terminal (V1) and the luminance level power supply terminal (V2) in series are applied. The method of claim 8, The gate driving voltage is a method of driving an electron-emitting device, characterized in that the voltage of the brightness level power supply terminal (V2) is applied after the voltage stabilization time of the gate driving power supply terminal (V1). The method of claim 9, And the voltage of the luminance level power supply terminal (V2) is applied by a delay signal while the stabilization time of the gate driving power supply terminal is reached.

Images