KR20010002340A - Method For Driving Display Of Passive Matrix Type and Apparatus Thereof - Google Patents

Abstract

PURPOSE: A drive apparatus and a method for simple matrix type displayer are provided to control the level of a floating voltage applied to a data electrode using the floating voltage and a switching element, thereby preventing the cross talk due to the influence of voltage supplied to non-driven pixels. CONSTITUTION: The drive apparatus and method for simple matrix type displayer comprises a PAEL(Plasma Address Electro-Luminescence) panel(42), a cathode driver(44), an anode driver(46), first/second data drivers(48,50), a floating voltage generator(58), a switch controller(56), a data pulse generator(52) and a timing controller(54). The cathode driver(44) and the anode driver(46) respectively drive the cathode lines(Km) and anode lines(Am) of the PAEL panel(42). The data drivers(48,50) respectively drive even and odd data lines(Dn-1, Dn) of the PAEL panel(42). The generator(58) are commonly connected to the data drivers. The switch controller(56) is connected to the generator(58). The timing controller(54) is commonly connected to the drivers(48,50) and the controller(56).

Description

Method and device for driving simple matrix display device {Method For Driving Display Of Passive Matrix Type and Apparatus Thereof}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of driving a display device driven by a simple matrix method, and more particularly, to a method and an apparatus for driving a simple matrix display device capable of preventing mis-discharge.

Recently, as the demand for flat panel display devices increases, liquid crystal displays (LCDs), field emission displays (FEDs), plasma display panels (PDPs), and plasma address liquid crystals BACKGROUND ART Researches on plasma address liquid crystal (PALC) display devices, electroluminescence (EL) display devices, and the like are being actively conducted. The LCD uses the electro-optical properties of the liquid crystal to display an image by driving the liquid crystal cell according to the video signal to adjust the light transmission amount. The PDP element displays an image by addressing and holding a discharge cell using discharge. The PALC display uses an electric discharge to address liquid crystal cells to display an image. The EL display device uses electroluminescence, and uses a mechanism of inducing and emitting light in the light emitting layer by applying an electric field to the fluorescent compound.

Among them, the simple matrix type of LCD and the PALC and EL display elements are driven in a simple matrix type. However, the simple matrix type driving method has a limitation in improving performance due to a crosstalk problem. Hereinafter, the problem of the simple matrix type driving method will be described in detail with reference to the EL display element.

Referring to Fig. 1, the structure of a general EL display element is shown.

In FIG. 1, the panel is formed on the first and second insulating layers 6 and 10, the light emitting layer 8 located between the first and second insulating layers 6 and 10, and the first insulating layer 10. And a transparent electrode 4 formed between the second insulating layer 6 and the substrate 2. The first and second insulating layers 6 and 10 are made of a dielectric material and have a predetermined capacitance value. The light emitting layer 8 is made of ZnS, Mn, or the like, and is excited by electrons to emit light to generate visible light. The back electrode 12 is a scanning electrode made of a metal material such as Al. The transparent electrode 4 is used as a data electrode to which data is applied.

When a voltage is applied between the back electrode 12 and the transparent electrode 4 in the EL display element of this structure, electrons in the light emitting layer 8 are accelerated by an electric field as shown in Fig. 2A. The accelerated electrons impinge on the light emitting center made of the phosphor material as shown in FIG. 2B to excite the light emitting center 8A. The light emitting center 8A is excited and then transitions to the ground state to emit visible light. When an AC pulse signal is applied to the back electrode 12 and the transparent electrode 4, the polarity of the electric field is reversed, and the electrons continuously excite the light emitting center 8A.

FIG. 3 briefly shows a simple matrix structure of the EL display element, and FIG. 4 shows a drive waveform supplied to the simple matrix display element of FIG.

The EL display element shown in FIG. 3 has a pixel cell 14 provided at an intersection of the first to fourth scan electrode lines K1 to K4 and the first to third data electrode lines D1 to D3. . Scan signals as shown in FIG. 4 are sequentially supplied to the first to fourth scan electrode lines K1 to K4. Whenever the scan signal is supplied to the first to fourth data electrode lines D1 to D3, a data signal corresponding to the scan line is synchronously supplied. In this case, each pixel cell 14 may be configured as an equivalent circuit in which the capacitor C and the diode D are connected in parallel. Here, the first to fourth scan electrode lines K1 and K2 are commonly connected to ground. When a scan signal is supplied to the first scan electrode line K1 and a data signal is supplied to the first to third data electrode lines D1 to D3, a data signal having a voltage value proportional to the luminance level is supplied. Accordingly, pixel cells included in the first scan lines emit light according to data voltage values. However, when an arbitrary voltage is applied to the first data electrode line D1, the voltage difference with the ground level of the second to fourth scan electrode lines K2 to K4 crossing the first data electrode line D1 may be caused. Data voltages are charged in the pixel cells included in the first column line. The charge voltage is discharged to the second scan electrode line K2 when the second scan line is driven, and excessive leakage current flows in the second scan electrode line K2, which may cause device breakdown, and between pixel cells. There is a problem that crosstalk occurs.

As described above, in the conventional simple matrix driving method, excessive leakage current is generated and crosstalk between pixel cells is generated, thereby limiting performance.

Accordingly, it is an object of the present invention to provide a method and apparatus for driving a simple matrix display device capable of preventing crosstalk between pixel cells.

1 is a diagram showing the structure of a general EL display element.

2A and 2B are diagrams showing light emission in steps of the EL display element shown in FIG.

3 is a view schematically showing the structure of a simple matrix display device.

4 is a diagram illustrating a driving waveform supplied to the simple matrix display device of FIG. 3.

FIG. 5 is an equivalent circuit diagram of the pixel cell shown in FIG. 3. FIG.

6 is a diagram illustrating a pixel cell structure of a plasma address electroluminescence display device applied to a method of driving a simple matrix display device according to the present invention;

FIG. 7 is an overall electrode arrangement view of a PAEL display device in which pixel cells shown in FIG. 6 are arranged in a matrix form.

8 is a driving waveform diagram corresponding to a method of driving a PAEL display device according to an exemplary embodiment of the present invention.

9 is an equivalent circuit diagram corresponding to one column line shown in FIG. 8.

10 is a view showing a driving device of the PAEL according to an embodiment of the present invention.

In order to achieve the above objects, the method of driving the simple matrix display device according to the present invention changes the base level of the data voltage applied to the data electrodes before the scan pulses are supplied to the scan electrode lines in an arbitrary horizontal period. Characterized in that it comprises the step of preventing the discharge.

A simple matrix type display device driving apparatus according to the present invention includes a simple matrix type display device in which a cell is provided at each intersection of a data electrode line and a scan electrode line, data driving means for supplying a data signal to the data electrode lines; A scan driving means for supplying a scan signal to the scan electrode lines, a timing controller for controlling the timing of the data driving means and the scan driving means in accordance with an input signal, and a negative basis selectively to the data electrode lines through the data driving means; And a floating voltage generator for applying a floating voltage having a level and a floating voltage having a base level of zero potential, and a controller for changing a floating voltage level of the floating voltage generator under control of a timing controller. do.

Other objects and advantages of the present invention in addition to the above object will be apparent from the description of the preferred embodiment of the present invention with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 6 to 10.

FIG. 6 illustrates a pixel cell structure of a plasma addressed electroluminescence (hereinafter referred to as PAEL) display device applied to a method of driving a simple matrix display device according to the present invention.

The PAEL display element is pre- filed by the present inventor to display an image by addressing the EL display element using discharge. This PAEL display element can be reduced in price and thickness by eliminating the back light, polarization filter, and dielectric glass thin film required by the PALC display element, and has the advantages of the wide viewing angle, low power consumption, and fast response speed of the EL display element. have. The display element of the PAEL includes a plasma discharge unit 20 and an EL unit 22 as shown in FIG. The plasma discharge unit 20 includes a lower substrate 24 on which the cathode 26 and the anode 28 are formed, and a partition wall (not shown) formed vertically on the lower substrate 24. The pair of anodes 26 and cathodes 28 cause plasma discharge in units of lines. The partition wall provides a discharge space together with the lower substrate 24 and the EL unit 22, and also divides the discharge space in units of lines. The plasma discharge unit 20 addresses the EL unit 22 by using discharge. The EL portion 22 includes the light emitting layer 32 positioned between the first and second insulating layers 30 and 34, the first and second insulating layers 30 and 34, the second insulating layer 34 and the upper portion. A transparent electrode 36 is formed between the substrate 38. The first and second insulating layers 30 and 34 are made of a dielectric material and have a predetermined capacitance value. The light emitting layer 32 is made of ZnS, Mn, or the like, and is excited by electrons to emit light to generate visible light. The light emitting layer 32 generates visible light of any one of red, green, and blue colors depending on the fluorescent material. The transparent electrode 36 is used as a data electrode to which data is applied. When discharge occurs in the plasma discharge unit 20, a virtual electrode electrically shorted with the anode 28 is formed. When the virtual electrode is formed by the discharge and the data voltage is applied to the transparent electrode 36, the light emitting layer 32 accelerates electrons of the light emitting layer 8 due to the voltage difference between the virtual electrode and the transparent electrode 36. Impinging and exciting the light emits visible light.

FIG. 7 illustrates an overall electrode arrangement diagram of a PAEL display device in which pixel cells illustrated in FIG. 6 are arranged in a matrix form. In FIG. 7, the m cathode lines K1 to Km and the anode lines A1 to Am are orthogonal to the n data lines D1 to Dn, and the pixel cells 40 as shown in FIG. Is provided.

8 illustrates a driving waveform corresponding to a method of driving a PAEL display device according to an exemplary embodiment of the present invention.

In the PAEL display element, data for one horizontal line is written and held normally in one horizontal period (H). 1 The horizontal period (H) is an initial period (IT) for addressing the corresponding scanning line of the EL portion by generating a discharge, a data capture period (DCT) in which data is written, and a decay for maintaining light emission. Period DT, that is, sustain period DS. In detail, during the initial period IT, a scanning pulse of about -350 V is applied to the first cathode line K1, so that a corresponding difference in the plasma portion is caused by the voltage difference between the first cathode line K1 and the first anode line A1. The discharge is generated in the discharge channel, that is, the first scan line. The virtual electrode is formed in the discharge channel where the discharge is generated, and the first anode line A1 and the first insulation layer 30 are electrically shorted, so that the first insulation layer 30 is connected to the first anode line A1. Equipotential. Subsequently, in the data capture period DCT, data pulses for one horizontal line are simultaneously supplied to the n data lines D1 to Dn. At this time, the data lines D1 to Dn are supplied with a pulse amplitude modulated (PAM) data pulse according to the gray scale value. In other words, data pulses having an amplitude corresponding to the gray scale value are supplied to the data lines D1 to Dn. When data pulses having different amplitudes, i.e., voltages, are supplied in this way, the electric field applied to the light emitting layer 32 is changed so that the intensity of light emission is changed. Then, the light emitting layer 32 maintains light emission during the sustain period DT until the potential of the virtual electrode due to the discharge is decayed until the discharge channel portion is turned off. In this manner, the first scan line is scanned during the first horizontal period H1, and the scan pulses are sequentially supplied to the second to mth cathode lines K2, K3, ..., Km-1, Km, and thus the nth scan line. When scanned up to 1 frame is completed.

However, since the PAEL display device has a simple matrix structure, when data is written, the data voltage is supplied to the discharge channel where the discharge is generated to express brightness, but the data voltage is also supplied to the other discharge channels where the discharge has not occurred. The insulating layer 30 is to be filled. For this reason, when a voltage is supplied to the second cathode line K2 to cause the discharge of the next scan line, the voltage supplied to the cathode line K2 and the previous stage hanging under the first insulating layer 30 are charged. A discharge occurs between the cathode line and the lower end of the first insulating layer in the difference between the supplied or supplied data voltage. In this case, the voltage across the lower end of the first insulating layer 30 is higher than the potential of the anode line. As described above, unwanted discharge occurs, and the light emitting layer 32 is subjected to a high voltage, which may cause damage to the light emitting layer 32. In order to prevent this, the floating voltages of the diode D and the capacitor C and the first and second switch elements SW1 and SW2 are used as an equivalent circuit corresponding to one column line shown in FIG. 9. .

In detail, in FIG. 9, Cel denotes a capacitance value of the light emitting layer 32, Cd denotes a capacitance value of the first insulating layer 30, and ch1 to chm denote anode lines A1 to Am and the first insulating layer ( 30 shows a discharge channel switch virtually existing between them. Each of the discharge channel switches ch1 to chm is turned on / turned off according to whether discharge is generated. According to the turn-on / turn-off of the first and second switches SW1 and SW2, the base level of the positive voltage maintains a '0' or negative voltage (-V) state. As shown in FIG. 8, the second switch SW2 is turned on before and after the scanning pulse is supplied. Accordingly, since the base level of the anode voltage Va maintains the negative voltage −V, a negative potential is applied to the lower end of the first insulating layer 30, so that discharge with the cathode line does not occur. Then, after the data voltage is supplied, the second switch SW2 is turned off and the first switch SW1 is turned on so that the base level of the anode voltage Va becomes '0' as conventionally. A positive voltage Va is applied to the lower end of the first insulating layer 30 to emit light by applying an electric field to the light emitting layer 32. In other words, before the data voltage is applied, the base level of the anode voltage Va is changed to a negative level to prevent erroneous discharge, and after the day voltage is applied, it is changed to the level of '0' to allow normal operation. do.

10 shows a driving device of a PAEL according to an embodiment of the present invention. The driving device of the PAEL of FIG. 10 includes a PAEL panel 42, a cathode drive unit 44 for driving cathode lines K1 to Km of the PAEL panel 42, and anode lines of the PAEL panel 42 ( The anode driver 46 for driving A1 to Am and the first data driver for driving the odd-numbered data lines D1, D3,..., Dn-3, Dn-1 of the PAEL panel 42 ( 48, a second data driver 50 for driving even-numbered data lines D2, D4,..., Dn-2, and Dn of the PAEL panel 42, and first and second data drivers 48. Floating voltage generator 58 connected in common with reference numeral 50, switch controller 56 connected to floating voltage generator 58, first and second data drivers 48, 50, and switch controller 56. ), And a timing controller 54 commonly connected to the negative electrode driver 44, the positive electrode driver 46, and the data pulse generator 52. PAEL panel 42 has a configuration as shown in FIG. The cathode driver 44 sequentially supplies the scanning pulses to the m cathode lines K1 to Km every initial period IT of one horizontal period under the control of the timing controller 54. The anode driver 46 supplies a common voltage capable of causing discharge to the scanning pulses supplied to the m anode lines A1 to Am under the control of the timing controller 54. Each of the first and second data drivers 48 and 50 may include the odd-numbered data lines D1, D3,..., Dn-3, and Dn-1 and even-numbered data lines for each data capture period DCT of one horizontal period. Data for one horizontal line is supplied to D2, D4, ..., Dn-2, Dn). The data pulse generator 52 generates a pulse amplitude modulated data pulse according to the gradation level under the control of the timing controller 54 and supplies it to the first and second data drivers 48 and 50. The timing controller 54 generates and supplies timing signals necessary for the cathode driver 44, the anode driver 46, and the data pulse generator 52 in response to the vertical and horizontal synchronization signals included in the input signal. In addition, the timing controller 54 supplies timing signals to the switch controller 56 to select the floating voltage level as described above. The switch controller 56 selectively turns on / turns off the first and second switches SW1 and SW2 of the floating voltage generator 58 in accordance with a timing signal from the timing controller 54 to thereby float the voltage level. That is, the base level of the anode voltage Va is selected. The floating voltage generating unit 58 supplies the floating voltage selected under the control of the switch control unit 56 to the data lines D1 to Dn through the first and second data driving units 48 and 50, thereby causing the electric discharge and the EL to be discharged. It is possible to prevent damage to the parts.

As described above, according to the method and apparatus for driving the simple matrix display device according to the present invention, the influence of the voltage supplied to the undriven pixel by changing the level of the floating voltage applied to the data electrode using the floating voltage and the switch element. This can prevent crosstalk problems. As a result, a simple matrix display device can be improved in performance. In addition, according to the method and apparatus for driving the simple matrix display device according to the present invention, only the PAEL display device is described, but it can be easily applied to all the display devices of the simple matrix type.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (6)

In a driving method of a simple matrix display device in which a cell is provided at each of intersection points of a data electrode line and a scan electrode line, A simple matrix display comprising the step of varying the base level of the data voltage applied to the data electrode lines to prevent mis-discharge before the scan pulses are supplied to the scan electrode lines in an arbitrary horizontal period. Device driving method. The method of claim 1, And the base level of the data voltage is varied to have a negative level. The method of claim 1, And changing the base level of the data voltage to have a zero level after the erroneous discharge prevention step. A simple matrix display device in which a cell is provided at each intersection of the data electrode line and the scan electrode line; Data driving means for supplying a data signal to the data electrode lines; Scan driving means for supplying a scan signal to the scan electrode lines; A timing controller which controls timing of the data driving means and the scan driving means in accordance with an input signal; A floating voltage generator for applying a floating voltage having a negative base level and a floating voltage having a base level of zero potential to the data electrode lines through the data driving means; And a control unit for changing the floating voltage level of the floating voltage generator according to the control of the timing controller. The method of claim 4, wherein The control unit A floating voltage having a negative base level is applied before a scan pulse is supplied to the scan electrode lines. And a floating voltage having a ground level of zero potential is applied to the data electrode lines after the scanning pulse is supplied. The method of claim 4, wherein The simple matrix display device is a drive device for a simple matrix display device, characterized in that the display device for addressing the electroluminescence device by plasma discharge.