KR20050009580A - Transient cross-talk preventing method of big matrix display - Google Patents

Abstract

PURPOSE: A method for preventing temporary crosstalk of a large screen display is provided to prevent the flow of a leakage current to a data electrode by applying a sawtooth reset pulse having the same negative pulse as a scan pulse to the data electrode. CONSTITUTION: According to the method for preventing temporary crosstalk of a large screen display, a data pulse(501) is supplied to a number of data electrodes. A scan pulse(503) is supplied to the data electrodes by being synchronized to the data pulse. A number of positive sawtooth reset pulses are supplied to a number of scan electrodes in order to remove charges charged in a cell where the scan pulse and the data pulse are supplied.

Description

Transient cross-talk preventing method of big matrix display}

The present invention applies a plurality of sawtooth reset pulses to a scan electrode or a data electrode to prevent crosstalk between data and scan when driving a matrix display having a large capacitor component to prevent current from flowing in the data electrode toward the scan electrode. Or a method for preventing cross talk between cells.

In the general matrix structure, the display can be driven with the same driving conditions only when the charge charged in the cell is removed. This is inevitable in simple matrix displays. Therefore, in most driving, a reset pulse is applied to remove the leakage current applied to the cell.

In the matrix type display, since the capacitance component is very large and has diode characteristics, it is basically discharged by applying a reset pulse of a sawtooth wave immediately before the scan pulse, which has an energy that does not affect the cell before the scan pulse, rather than applying a normal reset pulse to the cell. Let's do it. As a result, the reverse current does not flow even if a reverse bias occurs due to the phase difference between the waveform of the data electrode and the scan pulse.

The voltage applied to the cell as a whole depends on the previous and current voltages applied to the cell. The damage to a cell by this can be either large or small. This is inevitable in the matrix, but controlling it with the right energy can prevent reverse currents flowing into the cell without damaging the cell, which in turn prevents crosstalk.

Recently, various flat display devices capable of reducing weight and volume, which are disadvantages of cathode ray tubes, have been developed. Such flat panel displays include Liquid Crystal Display (LCD), Field Emission Display (FED), Plasma Display Panel (PDP) and Electro-Luminescence (EL). Etc. In such flat display devices, research and development are being actively conducted to increase the brightness, contrast, and color purity of flat display devices in order to improve display quality.

The double FED displays an image using light generated by colliding electrons emitted from the field emission array with the phosphor. The FED may be a tip type (FE type), a flat type (MIM or MIS type), or a surface conduction type (SCE type).

In the FED type field emission display device, a voltage is applied to a gate electrode to apply an electric field to an electron emission portion to emit electrons from a cone-shaped protrusion made of silicon or molybdenum. In the MIM type or MIS type field emission display device, a stacked structure including a metal, an insulator layer, a semiconductor layer, and the like is formed, and electrons are injected into and passed through the insulator layer from the metal layer side by using a tunnel effect. Withdraw. In addition, in the SCE type field display device, current flows in the in-plane direction of a thin film formed on a substrate, thereby emitting electrons from a pre-formed electron emitting portion (generally, a minute crack portion present in the conduction region of the thin film).

Among them, the planar FED has a structure in which a metal, an insulating layer, and a semiconductor layer are stacked, and emits electrons using a tunnel effect. The planar FED can be driven at a lower voltage of about 10V to about 10V lower than the tip type FED, and also has an advantage that the electrons are emitted in a straight line and the emission efficiency is high. Therefore, research on planar FED has been actively conducted in recent years.

1 is a cross-sectional view illustrating a pixel cell of a general planar field emission display device according to an exemplary embodiment of the prior art.

In the above embodiment, the pixel cell of the planar field emission display device includes an upper substrate 100, a lower substrate 102, and a field emission array formed on the lower substrate 102 on which the anode electrode 104 and the phosphor 106 are stacked. 108.

Referring to FIG. 1, the field emission array 108 is formed on the scan electrode 114 formed on the lower substrate 102, the insulator layer 112 formed on the scan electrode 114, and the insulator layer 112. The data electrode 110 is formed. The scan electrode 114 receives a scan pulse from a scan driver not shown. The data electrode 110 receives a data pulse from a data driver not shown. The insulator layer 112 insulates the scan electrode 114 and the data electrode 110.

In order to display an image, a positive voltage is applied to the anode electrode 104 on the upper substrate 100. In addition, a scan pulse of negative polarity (−) is applied to the scan electrode 114 on the lower substrate 102, and a data pulse of positive polarity (+) is applied to the data electrode 110. In this way, some electrons of the scan electrode 114 are tunneled to the insulator layer 14 and accelerated toward the phosphor 106. The electrons thus accelerated collide with the phosphor 106 of red (R), green (G), and blue (B) to excite the phosphor 106. At this time, visible light of any one of red (R), green (G), and blue (B) is generated in accordance with the phosphor 106 to display an image.

Typically, such planar FED cells are located at the intersection of the data line and the scan line. The driving unit for driving the planar FED cell includes a data driver for supplying data pulses to the data lines, and a scan driver for supplying scan pulses to the scan lines.

FIG. 2 is a waveform diagram illustrating a driving waveform supplied to the field emission display shown in FIG. 1.

2, negative scan pulses SP are sequentially supplied to scan electrodes S of a conventional FED, and positive polarities are synchronized to negative scan pulses SP to data electrodes D. FIG. The data pulse DP is supplied. In the pixel cells supplied with the scan pulse SP and the data pulse DP, electrons are emitted by the voltage difference between the scan pulse SP and the data pulse DP.

For example, as shown in FIG. 3, when -5V scan pulse SP is applied to the first scan electrode S1 and 5V data pulse DP is applied to the data electrode D, the first scan electrode S1 is applied. ), A voltage difference of 10V is generated in the first pixel cells P1 formed in FIG. Therefore, electrons are emitted from the first pixel cells P1 supplied with the data pulse DP.

At this time, the width and / or amplitude of the data pulse DP is set differently according to the gradation. For example, the width and / or amplitude of the data pulse DP is set to be wide or high when expressing a high gray level, and the width and / or amplitude of the data pulse DP is set to be narrow or low when expressing a low gray level.

Meanwhile, electrons are not emitted because only 5V, that is, data pulses DP, is applied to the second to mth pixel cells P2 to Pm formed on the second to mth scan electrodes S2 to Sm.

Thereafter, the above process is repeated to sequentially apply the scan pulse SP and the data pulse DP to the m th scan electrode Sm to drive the first to m th pixel cells P1 to Pm to display an image. do. After the image is displayed, a positive reset pulse RP is applied to the first to m th scan electrodes S1 to Sm. When the reset pulse RP is applied to the first to mth scan electrodes S1 to Sm, the charges charged in the first to mth pixel cells P1 to Pm are removed.

However, in the conventional FED, the data pulse is also applied to the second to m th scan electrodes when the first scan electrodes are driven. A predetermined voltage is applied to the second to m-th scan electrodes supplied with the data pulses, and the capacitance of the pixel cells is increased by the predetermined voltage. On the other hand, the same phenomenon occurs when the pixel cells formed on the second to m th scan electrodes are driven.

In other words, in the conventional FED, uniformity of pixel cells is different because data pulses are applied to all scan electrodes when one scan electrode is driven. As such, when the pixel cells operate in a non-uniform state, the image quality of the FED is degraded. In addition, the driving speed is lowered and the efficiency is lowered by the capacitance value charged in the non-operated pixel cells.

As such, when one reset pulse is applied, all of the charges charged in the pixel cells are not removed. That is, in the conventional FED, since one reset pulse is applied, the uniformity of the cell is lowered.

MIM (metal insulator metal) is an electrode structure formed of a thin film in the structure, the role of the reset pulse (reset pulse) is very important because the resistance component and the capacitor component is very large. If the screen gradually goes to a large screen, the capacitance of the panel becomes large, which means that the charging time of the cell becomes longer, which causes crosstalk due to time overlap (overlap) between adjacent scan lines. In addition, there has been a problem in the uniformity of the entire screen, such as the phenomenon that the cells once charged due to the large capacitors do not discharge quickly, causing screen overlap between adjacent cells or frames.

The present invention has been made to solve the problems of the prior art, the object of which is a plurality of sawtooth waves before scanning the scan line on the scan electrode to reduce the crosstalk generated when driving the matrix type (type) screen Supply a reset pulse to the whole to prevent leakage current from flowing to the data electrode, or apply a sawtooth reset pulse with the same negative pulse as the scan pulse to prevent crosstalk of the large display. To provide a way to.

1 is a cross-sectional view of a general cell structure of a field emission display device according to an embodiment of the prior art.

FIG. 2 is a waveform diagram illustrating a method of driving the field emission display device illustrated in FIG. 1, according to an exemplary embodiment.

3 is a diagram illustrating an arrangement of pixel cells of the field emission display device illustrated in FIG. 1, according to an exemplary embodiment.

4 is a block diagram illustrating a scan drive according to an embodiment of the present invention.

5 is a scan waveform diagram of a scan driving in which a reset pulse is applied to a scan electrode according to an exemplary embodiment of the present invention.

FIG. 6 is a waveform diagram illustrating the entire data driving in which a reset pulse is applied to a data electrode according to an exemplary embodiment of the present invention.

7 is a detailed block diagram of a scan pulse driver for generating the scan pulse of FIG. 4 according to an exemplary embodiment of the present invention.

FIG. 8 is a detailed block diagram of a data pulse driver generating the data pulse of FIG. 5 according to an embodiment of the present invention.

<Description of Major Symbols in Drawing>

100: upper substrate 102: lower substrate

104: anode electrode 106: phosphor

108: field emission array 110: data electrode

112: insulating layer 114: scan electrode

401: scan pulse driver 402: timing controller

403: First buffer 404: Photo coupler

405: second buffer 406: drive integrated circuit

407: ground 501: data pulse

502: positive reset pulse 503: scan pulse

602: negative reset pulse

701: sawtooth waveform reset pulse generator (in scan pulse)

801: sawtooth waveform reset pulse generator (in data pulse)

In order to achieve the above object, the present invention provides a crosstalk prevention method for a large screen matrix display, the method comprising: supplying data pulses to a plurality of data electrodes, and sequentially scanning the scan pulses to the plurality of scan electrodes in synchronization with the data pulses; And supplying a plurality of sawtooth-shaped positive reset pulses to the plurality of scan electrodes to remove charges charged in the cells supplied with the scan pulses and the data pulses.

In the present invention, the scan electrodes are preferably supplied with one positive sawtooth waveform reset pulse to each of the plurality of scan electrodes after the scan pulses are supplied to the one scan electrode.

In the present invention, the sawtooth-type reset pulse is preferably supplied between the scan pulses supplied to the i (i is an integer greater than or equal to 0) th scan electrode and the i + 1 th scan electrode.

In the present invention, the sawtooth reset pulse is preferably set in the same phase as the phase at which the i (i is an integer greater than or equal to zero) the falling end of the sawtooth reset pulse and the phase at which the i + 1 th scan pulse starts rising.

In the present invention, preferably, the plurality of sawtooth waveform negative reset pulses are supplied to the plurality of data electrodes instead of the plurality of sawtooth reset pulses supplied to the plurality of scan electrodes.

In the present invention, after the data pulses are supplied to the plurality of data electrodes, a step of supplying one negative sawtooth waveform reset pulse to each of the plurality of data electrodes is provided.

In the present invention, the sawtooth reset pulse is preferably supplied between the data pulses supplied to the i (i is an integer greater than or equal to 0) and the i + 1 th data electrode.

In the present invention, the sawtooth reset pulse is preferably set in the same phase as the phase at which the i-th sawtooth reset pulse starts to fall and the i + 1th data pulse starts to rise.

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

4 is an overall block diagram of a scan driver according to an embodiment of the present invention.

In the above embodiment, the scan driver includes a scan pulse driver 401, a timing controller 402, a first buffer 403, a photo coupler 404, a second buffer 405, a drive integrated circuit 406, and a ground ( 407).

The part indicated by the dotted line is the core of the present invention. The input voltage is supplied to the Vdd terminal of the driving IC 406 around the driving direct element (hereinafter referred to as the driving IC) 406 so that the reset pulse voltage and 0V are supplied. The switch element is used to control the voltage, and the input voltage is controlled to the Vss terminal of the driver IC by using the switch element to apply -Vd and 0V. It is possible to allow the voltage applied to the driving IC 406 (the voltage applied between Vdd and Vss) not to be fixed at a constant level but to be positive or negative.

For example, in order to produce a waveform as shown in FIG. 5, the timing controller 402 operates a switch such that the Vss terminal of the driving IC is selected as 0V or -Vd as shown in FIG. 7, and the scan pulse is a switch element of -Vd voltage. Outputs when is shorted. At non-scanning time, switch Q3 is grounded to the ground terminal.

Since the remaining portions except for the dotted line are the same as the configuration of the prior art, the description thereof is omitted (see Publication No. 2002-0087692). The remaining circuits excluding the dotted lines are provided to the first buffer 403, the photocoupler 404, and the second buffer 405 to transfer the control signal output from the timing controller 402 and the timing controller to the driving IC 405. It is composed.

5 is an overall waveform diagram of a scan pulse wave generated in the scan driver according to an embodiment of the present invention.

In this embodiment, the scan pulse includes a plurality of reset pulses, and the reset pulses overlap the data pulse rising portions.

Referring to FIG. 7, the reset pulse is applied to the scan electrode in the form of a positive sawtooth wave just before the start of the scan pulse. The reason is that negative charge is accumulated in the scan electrode by the negative scan pulse, so that it is discharged by the positive reset pulse.

If the phase of the data pulse and the scan pulse are different, that is, the data pulse is ahead of the scan pulse, the cell is charged with charge. If this continues, leakage current flows between cells, so that a voltage other than the actual voltage may be applied.

However, by applying the sawtooth waveform reset pulse to the scan electrode at the time when the scan pulse and the data pulse are in phase, the sawtooth waveform reset pulse is already applied to the scan electrode before the data pulse rises. Accordingly, even when the charge charged in the data electrode is discharged and the next data pulse is input to the data electrode, the charge charged in the cell cannot exist due to the sawtooth waveform reset pulse, thereby reducing the leakage current between the data electrode and the scan electrode. have.

As described above, the reason why the reset pulse of the sawtooth waveform is applied to the scan electrode is that the current of the reset pulse is different depending on the pulse width and the voltage. This is because a reverse bias on the electrode damages the cell.

This function is very effective for the cell's reliability and lifespan because it is a means to extend the life of the cell.

6 is a waveform diagram of a sawtooth waveform reset pulse applied to a data electrode according to an exemplary embodiment of the present invention.

In this embodiment, the data pulse comprises a plurality of reset pulses.

Referring to FIG. 6, a conventional scan pulse is applied to the scan electrode, but the data pulse generated from the data electrode is output in synchronization with the scan pulse, but when this is completed (or before), a negative sawtooth pulse is applied to the data electrode. By resetting the cell, leakage current can be reduced. The reason why the negative sawtooth pulse is applied is to cause the positive charge charged in the data electrode by the positive data pulse to be discharged by the negative sawtooth wave.

7 is a detailed block diagram of a scan pulse driver according to an embodiment of the present invention.

In the above embodiment, the scan pulse driver includes a reset pulse generator 701, a scan pulse generator, a push-pull switch, and an output terminal.

Referring to FIG. 7, when a scan pulse is generated, a scan pulse waveform of -Vd is generated while Q4 is shorted and Q3 is shorted or opened, and a reset pulse resets the sawtooth waveform of Vr with Q3 shorted and Q2 shorted or opened. Generate a waveform. The values of Vr and -Vd can be changed by level shift, and the generated scan pulse and reset pulse are output from the scan output terminal.

8 is a detailed block diagram of a data pulse driver according to an exemplary embodiment of the present invention.

In the above embodiment, the data driver for generating a sawtooth waveform reset pulse includes a data pulse generator, a reset pulse generator 801, a push-pull switch, and a data pulse output stage.

Referring to FIG. 8, in order to generate a data pulse, Q2 is shorted and Q3 is shorted or opened, and a 5V data pulse waveform is generated by the above operation. Q4 is shorted and Q3 is shorted or opened, and the sawtooth waveform of -Vd is generated. A reset pulse is generated. The generated data pulse and reset pulse are output at the data output terminal.

As described above, according to the present invention, by supplying a positive or negative sawtooth reset pulse to the data electrode or the scan electrode, it is possible to remove the charged particles accumulated in the cell and to allow the leakage current to flow to the data electrode. prevent.

And, by removing the leakage current as described above has the effect of preventing the crosstalk.

As described above, although described with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and modified within the scope of the present invention without departing from the spirit and scope of the present invention described in the claims below. It will be appreciated that it can be changed.

Claims (8)

Supplying data pulses to the plurality of data electrodes; Sequentially supplying scan pulses to a plurality of scan electrodes in synchronization with the data pulses; And a plurality of sawtooth-type positive polarity reset pulses are supplied to the plurality of scan electrodes in order to remove charges charged in the cells supplied with the scan pulses and the data pulses. The method of claim 1, wherein after the scan pulse is supplied to the one scan electrode, one positive sawtooth waveform reset pulse is supplied to each of the plurality of scan electrodes. The large screen as claimed in claim 1 or 2, wherein the sawtooth waveform reset pulse is supplied between the scan pulses supplied to the i (i is an integer greater than or equal to 0) th scan electrode and the i + 1 th scan electrode. How to prevent crosstalk in matrix displays. The crosstalk of a large-area matrix display according to claim 3, wherein the phase at which the i (i is an integer greater than or equal to 0) stops falling and the phase at which the i + 1 th scan pulse starts rising is the same. Prevention method. Supplying data pulses to the plurality of data electrodes; Sequentially supplying scan pulses to a plurality of scan electrodes in synchronization with the data pulses; And a plurality of sawtooth-type negative reset pulses are supplied to the plurality of data electrodes to remove the charges charged in the scan pulses and the cells supplied with the data pulses. The method of claim 5, wherein after the data pulses are supplied to the plurality of data electrodes, one negative sawtooth waveform reset pulse is supplied to each of the plurality of data electrodes. 7. The large screen as claimed in claim 5 or 6, wherein the sawtooth waveform reset pulse is supplied between the data pulses supplied to the i (i is an integer greater than or equal to 0) and the i + 1 th data electrode. How to avoid crosstalk in matrix displays. 8. The method of claim 7, wherein the phase at which the sawtooth waveform reset pulse falls and the phase at which the i + 1 th data pulse begins to rise are the same.