KR100480157B1 - Driving method of plasma display panel - Google Patents

Abstract

The present invention relates to a method of driving a plasma display panel which can prevent linear reversal of gray scales and express linear gray scales.

In the method of driving a plasma display panel according to the present invention, a first luminance weight is assigned to a plurality of subfields, and a second luminance weight is set by subtracting an amount of light generated in the address period from the first luminance weight. It includes.

Description

Driving method of plasma display panel {DRIVING METHOD OF PLASMA DISPLAY PANEL}

The present invention relates to a method of driving a plasma display panel, and more particularly, to a method of driving a plasma display panel to prevent linear inversion and to express linear gray scales.

Plasma Display Panel (hereinafter referred to as "PDP") is a display device using visible light generated from a phosphor when vacuum ultraviolet rays generated by gas discharge excite the phosphor. PDP is thinner and lighter than Cathode Ray Tube (CRT), which has been the mainstay of display means, and has the advantage of being able to realize high definition large screen. PDP is composed of a plurality of discharge cells arranged in a matrix form, one discharge cell constitutes a pixel of the screen.

1 is a perspective view showing a discharge cell structure of a conventional three-electrode AC surface discharge type PDP.

Referring to FIG. 1, a discharge cell of a conventional three-electrode AC surface discharge type PDP is formed on a first electrode 12Y and a second electrode 12Z formed on an upper substrate 10, and on a lower substrate 18. The address electrode 20X is provided.

The upper dielectric layer 14 and the passivation layer 16 are stacked on the upper substrate 10 having the first electrode 12Y and the second electrode 12Z side by side. In the upper dielectric layer 14, wall charges generated during plasma discharge are accumulated. The protective layer 16 prevents damage to the upper dielectric layer 14 due to sputtering generated during plasma discharge and increases emission efficiency of secondary electrons. As the protective film 16, magnesium oxide (MgO) is usually used.

The lower dielectric layer 22 and the partition wall 24 are formed on the lower substrate 18 on which the address electrode 20X is formed, and the phosphor layer 26 is coated on the surfaces of the lower dielectric layer 22 and the partition wall 24. The address electrode 20X is formed in the direction crossing the first electrode 12Y and the second electrode 12Z.

The partition wall 24 is formed in parallel with the address electrode 20X to prevent ultraviolet rays and visible light generated by the discharge from leaking to the adjacent discharge cells. The phosphor layer 26 is excited by ultraviolet rays generated during plasma discharge to generate visible light of any one of red, green, and blue. Inert gas for gas discharge is injected into the discharge space provided between the upper substrate 10, the lower substrate 18, and the partition wall 24.

Such a PDP is driven by dividing one frame into several subfields having different discharge times in order to express gray levels of an image. Each subfield is further divided into a reset period for uniformly discharging the discharge, an address period for selecting the discharge cells, and a sustain period for expressing the gray scale according to the number of discharges.

For example, when the image is to be displayed with 256 gray levels, the frame period (16.67 ms) corresponding to 1/60 second is divided into eight subfields SF1 to SF8 as shown in FIG. In addition, each of the eight subfields SF1 to SF8 is divided into an address period and a sustain period. Here, the reset period and the address period of each subfield are the same for each subfield, while the sustain period is 2 ⁿ (n = 0,1,2,3,4,5,6,7) in each subfield. Is increased.

3 is a waveform diagram showing a driving method of a conventional three-electrode alternating surface discharge type PDP.

Referring to FIG. 3, one subfield is divided into a reset period for initializing the entire screen, an address period for writing data while scanning the entire screen in a linear order manner, and a sustain period for maintaining the light emission state of the cells in which the data is written. Lose.

First, in the reset period, the reset waveform RP is supplied to the first electrode lines Y1 to Ym. When the reset waveform RP is supplied to the first electrode lines Y1 to Ym, a reset discharge is generated between the first electrode lines Y1 to Ym and the second electrode lines Z1 to Zm to initialize the discharge cell. do.

In the address period, the scan pulse SP is sequentially applied to the first electrode lines Y1 to Ym. The data pulse Dp synchronized with the scan pulse SP is applied to the address electrode lines X1 to Xn. At this time, address discharge occurs in the discharge cells to which the data pulse Dp and the scan pulse SP are applied.

In the sustain period, the first and second sustain pulses SUSPy and SUSPz are supplied to the first electrode lines Y1 to Ym and the second electrode lines Z1 to Zm. At this time, sustain discharge is generated in the discharge cells in which the address discharge is generated.

In such a PDP, the brightness is determined by Equation 1.

Where B is brightness, A is subfield mapping information, k is the number of subfields, N is the subfield weight, and s is the one-discharge brightness of the sustain pulse.

Gain is obtained using the ratio of the number of sustains to the number of tones. In other words, gain = total sustain number / (gradation level -1). For example, when the total number of sustain is 255 and the total number of gray is 256, the gain is set to "1".

The subfield mapping information indicates selection information of the address period. For example, it is set to "1" if the discharge cell is selected in the address period, and to "0" if not selected in the address period. N represents a weight of the subfield corresponding to the current subfield number k. s represents the brightness generated by one sustain discharge.

For example, in a plasma display panel, the gain is set to 1 and includes 12 subfields, and the weight of the subfields is 1, 2, 4, 8, 16, 32, 32, 32, 32, 32, 32, 32 If set to 32, the brightness of the PDP is set as shown in Table 1.

Gradation Subfield weights brightness One 2 4 8 16 32 32 32 32 32 32 32 0 × × × × × × × × × × × × 0S One O × × × × × × × × × × × 1S 2 × O × × × × × × × × × × 2S ... ... ... 31 O O O O O × × × × × × × 31S 32 × × × × × O × × × × × × 32S ... ... ... 255 O O O O O O O O O O O O 255S

Here, "x" indicates that gradation is not expressed, and "O" indicates that gradation is expressed. As can be seen from Table 1, the PDP includes 12 subfields, and 256 gray levels are obtained using luminance weights of 1, 2, 4, 8, 16, 32, 32, 32, 32, 32, 32, and 32. Will be represented.

Table 1 shows the brightness of the PDP considering only the light generated by the sustain discharge. However, the PDP that is actually driven generates light not only by sustain discharge but also by reset discharge and address discharge. As such, when gray scales are represented including reset discharges, address discharges, and sustain discharges, gray level reverse phenomenon occurs as shown in FIG. 4. In other words, there is a case where the brightness of the PDP expressed in the gray level of n-1 is set brighter than the brightness of the PDP expressed in the gray level of n (n is a natural number).

In detail, as shown in Table 1, subfields having luminance weights of 1, 2, 4, 8, and 16 should be selected to represent 31 gray levels. Thus, in order to express 31 gray levels, address discharge occurs in five subfields. In contrast, in order to express 32 gray levels, a subfield having a luminance weight of 32 should be selected. Therefore, in order to express 32 gradations, address discharge occurs in one subfield. At this time, the luminance inversion between 31 and 32 gradations is generated by the light generated by the address discharge. In other words, 31 gradations generate light that is brighter than 32 gradations.

The brightness of the PDP including the light generated in the actual reset discharge and the address discharge is determined by Equation 2.

Where L is the number of subfields that are initially reset, r is the one discharge brightness of the reset pulse, and a is the one discharge brightness of the address pulse.

L represents the number of subfields in which reset discharge occurs. For example, if the PDP includes 12 subfields and a reset discharge occurs in these 12 subfields, L is set to 12.

In Equation 2, a matrix such as Equation 3 may be derived.

On the other hand, in the conventional PDP, in order to stabilize the sustain discharge in the sustain period, a sustain pulse pair is additionally supplied for each subfield. The brightness of the PDP including light generated in the sustain pulse pair is determined by Equation 4.

In Equation 4, a matrix like Equation 3 is derived, and values of r, a, and s can be obtained using the matrix. In fact, the value of r (single discharge brightness of reset pulse) is 0.208815 [cd / m2], and the value of a (single discharge brightness of address pulse) is 0.413396 [cd / m2], s (single discharge brightness of sustain pulse). ) Is represented by 0.44553 [cd / m 2]. Here, the values of r, a, and s are values calculated from equations, not actual brightness, and the values of r, a, and s can be substituted to obtain brightness similar to the actual brightness.

The brightness of the PDP including the discharge brightness of the reset pulse, the discharge brightness of the address pulse, and the brightness of the sustain pulse, that is, the brightness of the PDP according to Equation 4 may be expressed as shown in Table 2.

Gradation Subfield weights brightness One 2 4 8 16 32 32 32 32 32 32 32 0 × × × × × × × × × × × × 12r + 0a + 0s + 0s One O × × × × × × × × × × × 12r + 1a + 1s + 1s 2 × O × × × × × × × × × × 12r + 1a + 2s + 1s ... ... ... 31 O O O O O × × × × × × × 12r + 5a + 31s + 5s 32 × × × × × O × × × × × × 12r + 1a + 32s + 1s ... ... ... 255 O O O O O O O O O O O O 12r + 12a + 255s + 12s

In the gradation of "0" in Table 2, only the brightness of the reset pulse generated in the 12 subfills is shown. In gray scale of " 1 ", the sustain brightness corresponding to the luminance weight of 1, the brightness by one sustain pulse pair, the brightness by 12 reset pulses, and the brightness by one address discharge appear. Further, in the gradation of "31", the sustain brightness corresponding to the luminance weight of 31, the brightness by five sustain pulse pairs, the brightness by twelve reset pulses, and the brightness by five address discharges are displayed. In the gray level of " 32 ", the sustain brightness corresponding to the brightness weight of 32, the brightness by one sustain pulse pair, the brightness by 12 reset pulses, and the brightness by one address discharge appear.

Here, when r, a, and s values are substituted for 31 gray levels, the brightness of " 20.61184 " is expressed in the PDP. In addition, when r, a, and s values are substituted for 32 gray levels, the brightness of "17.62166" is expressed in the PDP. That is, in the conventional PDP, gray level reverse phenomenon occurs, and thus, an image having linear brightness cannot be represented.

Accordingly, it is an object of the present invention to provide a method of driving a plasma display panel which can prevent linear inversion and express linear gray scale.

In order to achieve the above object, the method of driving the plasma display panel according to the present invention includes the steps of assigning primary luminance weights to a plurality of subfields, and subtracting the amount of light generated in the address period from the primary luminance weights. And setting a luminance weight.

The second luminance weight is actually a gradation expressed.

The subfield to be driven by the primary luminance weight is set.

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The secondary luminance weight is set by further subtracting light generated by a sustain pulse pair additionally supplied to each subfield. The secondary luminance weight is obtained by subtracting a luminance weight of "2" from the primary luminance weight. It features.

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Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIG. 5.

Table 3 shows the gradations of the plasma display panel according to the embodiment of the present invention.

Gradation Subfield weights brightness 0 0 2 6 14 30 30 30 30 30 30 30 0 × × × × × × × × × × × × 12r + 0a + 0s + 0s One O × × × × × × × × × × × 12r + 1a + 0s + 1s 2 × O × × × × × × × × × × 12r + 1a + 0s + 1s ... ... ... 31 O O O O O × × × × × × × 12r + 5a + 22s + 5s 32 × × × × × O × × × × × × 12r + 1a + 30s + 1s ... ... ... 255 O O O O O O O O O O O O 12r + 12a + 232s + 12s

Here, "x" indicates that gradation is not expressed, and "O" indicates that gradation is expressed. In Table 3, the gain is set to "1".

As shown in Table 3, the PDP of the present invention includes 12 subfields. In addition, the primary luminance weighting value of the PDP is set to 1, 2, 4, 8, 16, 32, 32, 32, 32, 32, 32, 32 as in the prior art. Here, the gradation actually expressed in the PDP of the present invention is expressed by subtracting light generated from a pair of sustain pulses added in order to prevent erroneous discharge during address discharge and / or sustain period at the primary luminance weighting value of the PDP.

This will be described in detail as follows. As described in the above-mentioned prior art, the inversion of luminance is generated by light generated by the address discharge, the reset discharge, and the single discharge of the sustain pulse. Therefore, in order to prevent the reverse inversion of luminance, the light generated by the address discharge, the reset discharge, and the one time discharge of the sustain pulse may be subtracted from each subfield.

As described in Equation 4, the one-discharge brightness (a) of the address pulse and the one-discharge brightness (s) of the sustain pulse have almost similar values. In addition, the one-time discharge brightness of the reset pulse generates light having a lower brightness than the one-time discharge brightness of the address pulse and the one-time discharge brightness of the sustain pulse. In addition, the reset pulse is included in all subfields regardless of the address discharge. Therefore, if the brightness of the address discharge and the one-time discharge brightness of the sustain pulse are subtracted from all the subfields, the reverse phenomenon of the luminance can be prevented.

Therefore, in Table 3 according to an embodiment of the present invention, the primary luminance weighting values are 1, 2, 4, 8, 16, 32, 32, 32, 32, 32, 32, 32, and address discharge brightness and one time sustain. The luminance weight value actually expressed is set by subtracting the subfield weight value of "2" in consideration of the discharge brightness of the pulse. That is, the PDP of the present invention as shown in Table 3 has a luminance weight of 0, 0, 2, 6, 14, 30, 30, 30, 30, 30, 30, 30.

Meanwhile, as shown in Table 4, in order to express the gray scale of "31", when the gain is 1, the first to fifth subfields are driven. At this time, the gray scale of "22" is actually expressed in the PDP. That is, in the present invention, the subfield to be driven is set using the primary luminance weight. At this time, the gray scale is actually expressed by subtracting the light generated by the address discharge and the one time sustain pulse discharge at the first luminance weighting value.

In fact, in the PDP driven as shown in Table 4, linear gray scales are represented without reversal of gray scales as shown in FIG. In detail, when the values of r, a, and s are substituted in the gray scale of "31", the brightness of "16.60207" is expressed in the PDP. In addition, when r, a, and s values are substituted in the gray level of "32", the brightness of "16.730606" is expressed in the PDP. That is, in the PDP of the present invention, the gray level reversal phenomenon does not occur, and thus an image having linear brightness is represented.

As described above, according to the driving method of the plasma display panel according to the present invention, the gray scale is reversed by setting the gray scale by subtracting the brightness caused by the address discharge and the brightness of one additional sustain pulse pair inserted in all subfields. The phenomenon can be prevented. Accordingly, the plasma display panel of the present invention can express an image having linear brightness.

 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.

1 is a perspective view showing a discharge cell structure of a conventional three-electrode AC surface discharge type plasma display panel.

2 illustrates a plurality of subfields included in one frame of a conventional plasma display panel.

3 is a waveform diagram showing driving waveforms supplied to a conventional plasma display panel.

4 is a graph showing luminance according to gray scales displayed in a conventional plasma display panel.

5 is a graph showing luminance according to gray scales displayed in a plasma display panel according to an exemplary embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

10: upper substrate 12Y: first electrode

12Z: second electrode 14,22: dielectric layer

16: protective film 18: lower substrate

20X: address electrode 24: partition wall

26: phosphor layer

Claims (7)

In a driving method of a plasma display panel in which one frame is divided into a plurality of subfields, and each of the plurality of subfields includes an address period and a sustain period. Assigning primary luminance weights to the plurality of subfields; And subtracting an amount of light generated in the address period from the primary luminance weight to set a secondary luminance weight. The method of claim 1, And a gradation in which the second luminance weight is actually expressed. The method of claim 1, And a subfield to be driven by the primary luminance weight. delete The method of claim 1, And the second luminance weight is set by subtracting light generated by a pair of sustain pulses additionally supplied to each subfield. delete The method of claim 5, wherein And the secondary luminance weight is obtained by subtracting a luminance weight of "2" from the primary luminance weight.