KR20070056852A - Electron emission display for brightness control communication - Google Patents

Abstract

An electron emission display for brightness control communication is provided to increase response speed and efficiency of the electron emission display by minimizing delay time in voltage variable communication for brightness control. An electron emission display for brightness control communication includes a pixel unit(100), a data driving unit(200) for applying data signals to the pixel unit, a scan driving unit, a control unit and a D/A(Digital/Analog) converter. The scan driving unit(300) applies scan signals to the pixel unit. The control unit(500) calculates the sum of the image data signals inputted from the data driving unit and the scan driving unit and obtains the image level from the result. The D/A converter(400) converts the image level of an 8-bit parallel signal into a corresponding analog voltage level.

Description

Electronic emission display for brightness control communication {Electron Emission Display for brightness Control Communication}

1 is a view schematically showing a configuration of an electron emission display device for luminance control communication according to the related art.

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

FIG. 3 shows an example of a part of a pixel portion that can be employed in the electron emission display device shown in FIG. 1; FIG.

4 illustrates an example of a controller that may be employed in the electron emission display of FIG. 1.

5A-5C schematically illustrate a process of a data signal applied to the converter of FIG.

<Description of main parts of drawing>

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

300 --- Scan driver 400 --- D / A converter

500 --- control unit

The present invention relates to an electron emission display device for luminance control communication, and more particularly, to an electron emission display device for luminance control communication that can improve response speed and efficiency by minimizing a voltage variable communication delay time for luminance control. will be.

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, and 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 illustrating a configuration of an electron emission display device for luminance control communication according to the related art. 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 intersect, one of the scan line and the data line acts 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. In the present invention, a pulse width modulation (also referred to as PWM) data driving unit will be described. However, any data driving unit for adjusting the electron emission time of the electron emitting device in response to the input image data is the scope of the present invention. Included in

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

The power supply 40 includes a microcomputer 41 and a D / A converter 42. The first power supply VS1 is applied to the data driver 20, and the second power supply VS2 is applied to the scan driver 30. And the third power source VS3 is applied to the anode electrode.

The controller 50 includes a frame memory 51, a LUT 52, and an operation unit 53, and after obtaining an image level of the image data DATA, a voltage applied to the anode electrode corresponding to the obtained image level. And at least one of a voltage applied to the cathode electrode and a voltage applied to the gate electrode. 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. ).

On the other hand, in the above-described electron emission display device for controlling the brightness, the operation unit of the control unit converts the voltage level through the microcomputer of the power supply unit. At this time, as the number of pins of the microcomputer increases, the speed decreases.

Therefore, problems such as a communication delay time of a variable voltage according to data transmitted to the D / A converter through the microcomputer occur.

An object of the present invention is to provide an electronic emission display device for luminance control communication that can improve response speed and efficiency by minimizing a voltage variable communication delay time for luminance control.

In order to achieve the above object, an electron emission display device for luminance control communication according to the present invention comprises: a pixel portion; A data driver for applying a data signal to the pixel unit; A scan driver for applying a scan signal to the pixel portion; A control unit obtaining an image level by summing image data signals inputted from the data driver and the scan driver; It is characterized in that it comprises a D / A converter for receiving the video level of the control unit as an 8-bit parallel signal and converts it to a voltage level corresponding to the video level.

In particular, the video level of the control unit is divided into a frame data section, a logic interface section and a level conversion section is applied, and the conversion time of the voltage level of the level conversion section is characterized in that 200 ~ 300 ~.

In particular, the D / A converter converts the voltage level in the level conversion period applied from the controller, and the 8-bit interface time is 20 kHz.

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

2 is a view schematically showing an example of the structure of an electron emission display device according to the present invention. Referring to FIG. 2, the electron emission display device according to the present invention includes a pixel unit 100, a data driver 200, a scan driver 200, a D / A converter 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 the plurality of pixels 50 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 D / A converter 400 applies the first power source V1 and the second power source V2 to the scan driver 300, and the third power source V3 and the fourth power source V4 to the data driver 200. ) Is applied. In addition, the D / A converter 400 according to the control signal output from the control unit 500, the voltage applied between the scan driver 300 and the data driver 200, that is, the difference between the voltage between the cathode electrode and the gate electrode The luminance of the pixel unit 100 is compensated for by adjusting the voltage or the voltage applied to the anode.

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.

3 is a diagram illustrating an example of a part of a pixel unit that may be employed in the electron emission display device illustrated in FIG. 1. As shown therein, the pixel unit 100 includes an electron emission substrate 120 and an image forming substrate 130. In addition, the spacer 140 may be further included to maintain a constant distance 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 have at least one first opening 126 at the intersection 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.

4 is a diagram illustrating an example of a controller that may be employed in the electron emission display of FIG. 1. 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.

5A to 5C schematically illustrate a process of a data signal applied to the converter of FIG. 1. As shown in FIG. 5A, an image level of the controller is divided into a frame data section, a logic interface section, and a level converting section, and the conversion time of the voltage level in the level converting section is within 200 mW-300 mW. When the voltage is adjusted to the divided section, natural brightness control is possible without screen shaking.

As shown in FIGS. 5B and 5B, the D / A converter 400 converts a voltage level in a level conversion period applied by the controller, and an 8-bit interface time takes about 20 ms. In other words, the interface time is performed within 20 mW, and the voltage variation is made within 200 mW-300 mW.

In addition, the D / A converter 400 adjusts the image level output from the controller 500 to a voltage level corresponding thereto, and when the image level is high, the voltage is lowered, and when the image level is low, the voltage is reduced. Raised.

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 electronic emission display device for the luminance control communication of the present invention can minimize the voltage variable communication delay time for the luminance control to improve the response speed and efficiency.

Claims (6)

A pixel portion; A data driver for applying a data signal to the pixel unit; A scan driver for applying a scan signal to the pixel portion; A control unit obtaining an image level by summing image data signals inputted from the data driver and the scan driver; And a D / A converter which receives an image level of the controller as an 8-bit parallel signal and converts the image level into a voltage level corresponding thereto. The method of claim 1, And an image level of the controller is divided into a frame data section, a logic interface section, and a level converting section. The method of claim 1, And the D / A converter converts the voltage level in the level conversion period applied by the control unit. The method of claim 3, wherein And the conversion time of the voltage level in the level conversion section is 200 mW-300 mW. The method of claim 1, And an 8-bit interface time of the D / A converter is 20ms. The method of claim 1, And the D / A converter is a power supply unit.

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