KR100573136B1 - Method and apparatus for driving display panel - Google Patents

Abstract

The panel driving method according to the present invention is characterized in that the power consumption control is performed according to a cumulative average load ratio obtained by accumulating and averaging load rates of two or more frames.

Conventional power consumption control has been a constraint for improving the image quality of display panels by uniformly limiting the increase in luminance for reasons of product reliability.

According to the present invention, the cumulative average load ratio is newly defined, and power consumption control is performed at two or more levels accordingly. According to the present invention, if the cumulative average load ratio is less than or equal to a predetermined threshold value, the luminance can be improved by appropriately raising the power consumption level within a range that does not substantially add a load to the display panel. At this time, when the increased power consumption level may cause the reliability of the product to deteriorate, that is, when the cumulative average load rate exceeds a predetermined threshold, the power consumption level is restored.

Therefore, high quality of the display panel can be realized while maintaining the reliability of the display panel product.

Description

Display panel driving method and apparatus {Method and apparatus for driving display panel}

1 is a view showing the structure of a conventional three-electrode surface discharge plasma display panel.

FIG. 2 shows a typical driving apparatus of the plasma display panel shown in FIG. 1.

FIG. 3 shows a conventional address-display separation driving method for Y electrode lines of the plasma display panel of FIG. 1.

FIG. 4 is a timing diagram for explaining an example of a drive signal of the panel shown in FIG. 1.

5 is a graph illustrating a relationship between luminance and power consumption according to a load ratio of a plasma display panel.

6 is a flowchart illustrating a panel driving method according to an embodiment of the present invention.

7 is a graph showing a load ratio and power consumption for explaining power consumption control by the panel driving method of the present invention.

8 is a graph showing a relationship between load ratio and luminance for explaining power consumption control according to the panel driving method of the present invention.

9 is a block diagram illustrating a panel driving apparatus according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method and a driving apparatus for a display panel for displaying a screen by applying a sustain pulse to an electrode structure forming a display cell such as a plasma display panel (PDP). The present invention relates to a driving method and an apparatus.

1 is a view showing the structure of a conventional three-electrode surface discharge plasma display panel.

Referring to FIG. 1, between the front and rear glass substrates 100 and 106 of a conventional surface discharge plasma display panel 1, address electrode lines A ₁ , A ₂ ,..., A _m , Dielectric layers 102 and 110, Y electrode lines Y ₁ , ..., Y _n , X electrode lines X ₁ , ..., X _n , fluorescent layer 112, barrier rib 114, and As a protective layer, the magnesium monoxide (MgO) layer 104 is provided, for example.

The address electrode lines A ₁ , A ₂ ,..., A _m are formed in a predetermined pattern on the front side of the rear glass substrate 106. The lower dielectric layer 110 is applied in front of the address electrode lines A ₁ , A ₂ ,..., A _m . In front of the lower dielectric layer 110, barrier ribs 114 are formed in a direction parallel to the address electrode lines A ₁ , A ₂ ,..., A _m . The partition walls 114 function to partition the discharge area of each display cell and to prevent optical interference between the display cells. The fluorescent layer 112 is formed between the partition walls 114.

The X electrode lines X ₁ , ..., X _n and the Y electrode lines Y ₁ , ..., Y _n are address electrode lines A ₁ , A ₂ , ..., A _m . It is formed in a predetermined pattern on the back of the front glass substrate 100 to be orthogonal to the. Each intersection sets a corresponding display cell. Each X electrode line (X ₁ , ..., X _n ) and each Y electrode line (Y ₁ , ..., Y _n ) are transparent electrode lines (X _na ) made of a transparent conductive material such as indium tin oxide (ITO). , Y _na ) and metal electrode lines X _nb and Y _nb for increasing conductivity may be formed. The front dielectric layer 102 is formed by applying the entire surface to the rear of the X electrode lines (X ₁ ,..., X _n ) and the Y electrode lines (Y ₁ ,..., Y _n ). A protective layer 104 for protecting the panel 1 from a strong electric field, for example, a magnesium monoxide (MgO) layer, is formed by applying a front surface to the back of the front dielectric layer 102. The plasma forming gas is sealed in the discharge space 108.

A driving scheme generally applied to such a plasma display panel is a method in which initialization, address, and display holding steps are sequentially performed in a unit sub-field. In the initialization step, the charge states of the display cells to be driven are made uniform. In the address step, the charge state of display cells to be selected and the charge state of display cells not to be selected are set. In the display holding step, display discharge is performed in the display cells to be selected. At this time, a plasma is formed from the plasma forming gas of the display cells performing display discharge, and the fluorescent layer 112 of the display cells is excited by ultraviolet radiation from the plasma to generate light.

2 illustrates a general driving device of the plasma display panel of FIG. 1.

Referring to the drawings, a typical driving device of the plasma display panel 1 includes an image processor 200, a controller 202, an address driver 206, an X driver 208, and a Y driver 204. The image processing unit 200 converts an external analog image signal into a digital signal, and internal image signals, for example, 8-bit red (R), green (G) and blue (B) image data, clock signals, vertical and horizontal, respectively. Generate synchronization signals. The controller 202 generates the driving control signals SA, SY, and SX according to the internal image signal from the image processor 200. The address driver 206 processes the address signal SA among the drive control signals SA, SY, and SX from the controller 202 to generate a display data signal, and generates the display data signal through the address electrode lines. To apply. The X driver 208 processes the X driving control signal SX among the driving control signals SA, SY, and SX from the controller 202 and applies the X driving control signal SX to the X electrode lines. The Y driver 204 processes the Y driving control signal SY among the driving control signals SA, SY, and SX from the controller 202 and applies the Y driving control signal SY to the Y electrode lines.

As a driving method of the plasma display panel 1 having the above-described structure, an address-display separation driving method mainly used is disclosed in US Pat.

FIG. 3 illustrates a conventional address-display separation driving method for Y electrode lines of the plasma display panel of FIG. 1.

Referring to the drawings, a unit frame may be divided into a predetermined number, for example, eight subfields SF1, ..., SF8 to realize time division gray scale display. Each subfield SF1, ..., SF8 is divided into a reset section (not shown), an address section A1, ..., A8, and a sustain discharge section S1, ..., S8. do.

In each address section A1, ..., A8, a display data signal is applied to the address electrode lines AR1, AG1, ..., AGm, ABm in FIG. Scan pulses corresponding to..., Yn) are sequentially applied.

In each sustain discharge section S1, ..., S8, pulses for display discharge alternately in the Y electrode lines Y1, ..., Yn and the X electrode lines X1, ..., Xn. Is applied to cause display discharge in discharge cells in which wall charges are formed in the address periods A1, ..., A8.

The luminance of the plasma display panel is proportional to the number of sustain discharge pulses in the sustain discharge sections S1, ..., S8 occupied in the unit frame. When one frame forming one image is represented by eight subfields and 256 gray levels, each subfield is sequentially held at a ratio of 1, 2, 4, 8, 16, 32, 64, and 128 in order. The number of pulses can be assigned. In order to obtain luminance of 133 gray levels, cells may be addressed and sustained and discharged during the subfield 1 period, the subfield 3 period, and the subfield 8 period.

The number of sustain discharges allocated to each subfield may be variably determined according to the weights of the subfields according to the APC (Automatic Power Control) step. In addition, the number of sustain discharges allocated to each subfield is. Various modifications are possible in consideration of gamma characteristics or panel characteristics. For example, the gradation level assigned to subfield 4 may be lowered from 8 to 6, and the gradation level assigned to subfield 6 may be increased from 32 to 34. In addition, the number of subfields forming one frame can be variously modified according to design specifications.

FIG. 4 is a timing diagram for explaining an example of a driving signal of the panel shown in FIG. 1. X) and drive signals applied to the scan electrodes Y1 to Yn. Referring to FIG. 4, one subfield SF includes a reset period PR, an address period PA, and a sustain discharge period PS.

The reset period PR initializes the wall charge state of all cells by applying reset pulses to the scan lines of all groups and forcibly performing a write discharge. The reset period PR is performed before entering the address period PA, which is carried out over the entire screen, thus making it possible to create a wall distribution of wall charges with a fairly even and desired distribution. The cells initialized by the reset period PR have similar wall charge conditions in the cells. The address period PA is performed after the reset period PR is performed. At this time, in the address period PA, the bias voltage Ve is applied to the common electrode X, and the scan electrodes Y1 to Yn and the address electrodes A1 to Am are simultaneously turned on at the cell positions to be displayed. Select the display cell. After the address period PA is performed, the sustain discharge period PS is performed by alternately applying the sustain pulses Vs to the common electrodes X and the scan electrodes Y1 to Yn. During the sustain discharge period PS, a low level voltage VG is applied to the address electrodes A1 to Am. In PDP, the brightness is adjusted by the number of sustain discharge pulses. If the number of sustain discharge pulses in one subfield or one TV field is large, the luminance increases.

In the plasma display panel, APC (Automatic Power Control) is performed to limit the power consumption for reasons of reliability of the product.

5 is a graph illustrating a relationship between luminance and power consumption according to a load ratio of a plasma display panel. Referring to Figure 5 will be described APC (Automatic power control) as follows.

Referring to the luminance curve L, the luminance of the display panel is maintained at a substantially constant level up to a predetermined load factor. In this case, the luminance curve L means luminance per unit area. According to the APC, the luminance per unit area is reduced in accordance with an increase in the load rate to prevent an increase in power consumption.

Until a predetermined load factor, the luminance per unit area is maintained at a constant level. Therefore, referring to the power consumption curve P, the power consumption increases according to the load rate up to a predetermined load rate. Above a predetermined load rate, the power consumption is kept substantially constant according to the load ratio. In the plasma display panel, the number of sustain discharge pulses is reduced, thereby reducing the luminance per unit area and controlling the power consumption.

For example, in the case of 10 subfields SF1 to SF10 per frame, an APC table in which the number of sustain discharge pulses Ns is determined according to the load rate steps APC128 to APC1 is illustrated in Table 1 below.

SF1 SF2 … SF9 SF10 Ns APC128 One 2 … 32 64 314 APC127 2 4 … 43 85 456 : : : : : : : APC1 7 14 … 448 896 2200

Referring to Table 1, the load ratio decreases toward the bottom of the table. That is, in the APC, the larger the load ratio, the smaller the number of sustain discharge pulses.

However, this conventional APC operation is performed based on a single luminance curve as shown in FIG. 5.

According to the conventional APC of the display panel, the maximum power consumption is limited to a certain level or less as the load rate is increased based on the load rate per frame. Therefore, there is no choice but to limit the increase in luminance, which is an important factor of image quality, above a certain load factor.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a panel driving method and apparatus for improving luminance within a range that does not substantially add a load to a display panel.

The display panel driving method according to the present invention for achieving the above technical problem, it characterized in that the power consumption control according to the cumulative average load rate of the cumulative average load rate of two or more frames.

The panel driving method may alternatively perform power consumption control among two or more power consumption control reference curves according to the cumulative average load ratio.

The panel driving method may determine whether the cumulative average load rate belongs to an area divided by one or more threshold values, and select one of the number of power consumption control reference curves to perform power consumption control. Can be.

The panel driving method includes detecting a load rate per frame from input image data; Calculating the cumulative average load ratio; Selecting one of two or more power consumption control levels according to the cumulative average load ratio; And determining the number of sustain pulses according to the selected power consumption control level.

According to an aspect of the present invention, there is provided a display panel driving apparatus including: a load rate detection unit configured to detect a load rate per frame from input image data; A cumulative average load ratio calculating unit for calculating an average cumulative average load ratio by accumulating load rates of two or more frames; A storage unit storing two or more levels of power consumption control reference tables; A selection unit for selecting one of the two or more reference tables according to the cumulative average load ratio; And a holding pulse number setting unit configured to determine the number of holding pulses by the selected reference table.

The selector may determine whether the cumulative average load rate belongs to an area divided by one or more threshold values, and select one of the power consumption control reference tables corresponding to the number of the divided areas stored in the storage.

Hereinafter, the configuration and operation of a display panel driving method and apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the plasma display panel, the APC controls power consumption so that the plasma display panel operates in a safety operating area. In other words, the luminance, which is an important factor of image quality, is limited because of the reliability of the product.

The present invention has been devised to improve the luminance within a range that does not substantially add a load to the display panel. In the present invention, the concept of the cumulative average load ratio K is proposed as a criterion for determining whether to substantially add a load to the display panel. The cumulative average load ratio K is a cumulative average of load rates of two or more image frames, and may be calculated as shown in Equation 1 below.

Here, LR (n) means a load rate for each frame. In this case, the number of frames for calculating the integral period, that is, the cumulative average load rate may be determined as two or more values according to the display panel. The larger the integration section, the smaller the contribution of the load factor of one frame to the cumulative average load factor K. The designer can appropriately determine the size of the integration period in consideration of the frequency of applying the high quality APC mode according to the present invention and the degree of reliability of the product.

When APC is performed according to the cumulative average load rate K, power consumption control may be performed by reflecting a substantial increase in the load rate of the display panel. If the load rate suddenly increases in one frame, but the cumulative average load rate of several frames before and after the frame is small, the actual load rate of the display panel is not high. In this case, according to the cumulative average load ratio, the power consumption is not lowered suddenly in the frame.

6 is a flowchart illustrating a panel driving method according to an embodiment of the present invention.

Referring to FIG. 6, first, a load factor is detected from image data (S100).

The load factor is determined by the ratio of the number of display cells turned on and the total display cells.

After step S100, the cumulative average load ratio is calculated (step S102).

After step S102, an APC reference table to be applied is selected according to the cumulative average load ratio K (step S104). At least two APC reference tables are provided. One of these two or more APC reference tables is selected according to the cumulative average load factor. In this case, two or more APC reference tables are obtained from different power consumption curves according to load ratios, and luminance curves per unit area according to load ratios.

For example, in step S104, two or more APC reference tables are prepared, and based on a predetermined threshold m, the first APC reference table is selected if the cumulative average load ratio K≥m, and the second APC reference table is selected if the cumulative average load ratio K <m. It can be implemented to. Here, the threshold m is a value that can be obtained through the test, depending on the structural electrical characteristics of the display panel. In addition, when the threshold for distinguishing the cumulative average load rate K is two or more, for example, when the threshold values m1 and m2 are applied, it is determined whether the cumulative average load rate K falls within a range of K <m1, m1≤K <m2, and K≥m2 Accordingly, it may be implemented to select one of three APC reference tables.

The APC reference table may have a form as shown in Table 1, and two or more different APC reference tables may be implemented by differently setting the number of sustain discharge pulses for each subfield according to the load ratio step (APC128 to APC1).

After the step S104, from the selected APC reference table, the number of sustain pulses is determined according to the load ratio of the current frame (step S106). According to the determined number of sustain pulses, a panel driving signal as shown in FIG. 4 is generated to drive the display panel.

7 is a graph showing a relationship between load ratio and power consumption for explaining power consumption control by the panel driving method of the present invention, and includes a first APC curve and a second APC curve.

Here, the first APC curve is a low power consumption mode, the second APC curve is a high power consumption mode. Here, the first APC curve may consume power equivalent to that of the conventional art. In addition, the second APC curve consumes more power than the first APC curve, and implements high brightness for the same load rate.

In performing APC, the selection of the first APC curve or the second APC curve is determined according to the cumulative average load ratio K. For example, when the cumulative average load ratio K is greater than a predetermined reference value, the APC is performed to follow the first APC curve, which is a low power consumption mode. In addition, when the cumulative average load ratio K is smaller than a predetermined reference value, APC is performed to follow the second APC curve, which is a high power consumption mode. For example, based on the predetermined threshold m, the cumulative average load ratio K ≥ m may be selected to select the first APC reference table in low power consumption mode, and if the cumulative average load ratio K <m, the second APC reference table in high power consumption mode may be implemented. Can be.

8 is a graph showing a relationship between load ratio and luminance for explaining power consumption control by the panel driving method of the present invention, and includes a first APC curve and a second APC curve. The first APC curve and the second APC of FIG. 8 correspond to the first APC curve and the second APC curve of FIG. 9, respectively.

Referring to FIG. 8, the luminance of the display panel is increased when the second APC curve in the high power consumption mode is selected for the same load ratio than when the first APC curve is selected.

7 and 8 illustrate only a two-step APC mode, but those skilled in the art will understand that the APC mode may be implemented in three or more APC modes according to the cumulative average load ratio.

FIG. 9 is a block diagram illustrating a panel driving apparatus according to an exemplary embodiment of the present invention, wherein the load ratio detector 900, the cumulative average load ratio calculator 902, the APC reference table 906, and the selector 904 are illustrated. And a holding pulse number setting unit 908.

The load factor detection unit 900 detects a load factor per frame from the input video data IN.

The cumulative average load factor calculation unit 902 calculates a cumulative average load factor obtained by accumulating and averaging load rates of two or more detected frames.

The storage unit 906 stores two or more levels of power consumption control reference tables. 9 shows an example in which two reference tables are provided as first and second APC reference tables. Here, the first and second APC reference tables may correspond to the first APC curve and the second APC curve shown in FIGS. 7 and 8, respectively. Although two reference tables are illustrated in the drawing, three or more reference tables may be provided according to design specifications.

The selecting unit 904 selects one of the first APC reference table 906a and the second APC reference table 906b according to the inputted cumulative average load ratio. If three or more reference tables are provided, the selector 904 selects one of three or more reference tables according to the input cumulative average load ratio. The selection unit 904 may be implemented to determine whether the cumulative average load rate belongs to an area divided by one or more threshold values, and select one of the reference tables stored in the storage unit 906 according to the determination result. . Here, the number of reference tables stored in the storage unit 906 is equal to the number of regions divided by the one or more threshold values.

The sustain pulse number setting unit 908 determines the sustain pulse according to the load ratio from the selected reference table. The number of sustain pulses is allocated to a plurality of subfields constituting one frame, respectively.

The panel driving method according to the present invention described above can also be embodied as computer readable codes on a computer readable recording medium. Computer-readable recording media include any type of recording device that stores programs or data that can be read by a computer system. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, hard disk, floppy disk, flash memory, optical data storage, and the like. Here, the program stored in the recording medium refers to a series of instruction commands used directly or indirectly in an apparatus having an information processing capability such as a computer to obtain a specific result. Thus, the term computer is used to mean all devices having an information processing capability for performing a specific function by a program, including a memory, an input / output device, and an arithmetic device, regardless of the name actually used. Even in the case of a device for driving a panel, its use is limited to a specific field of panel driving, and in reality, it is a kind of computer. The panel driving apparatus according to the present invention illustrated in FIG. 9 may be implemented by being included in the logic controller 202 illustrated in FIG. 2.

In particular, the panel driving method according to the present invention is written in a schematic or ultra-high-speed integrated circuit hardware description language (VHDL) or the like on a computer, and connected to a computer-programmable integrated circuit such as a field programmable gate array (FPGA). Can be implemented. The recording medium includes such a programmable integrated circuit. The recording medium also includes an application specific integrated circuit (ASIC) in which logic circuits for driving the panel are integrated.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, according to the panel driving method and apparatus of the present invention, it is possible to implement a high picture quality by improving luminance than conventional power consumption control.

Until now, power consumption control, commonly referred to as APC, has been a constraint for improving the image quality of display panels by uniformly limiting the increase in luminance due to product reliability.

According to the present invention, the cumulative average load ratio is newly defined, and power consumption control is performed at two or more levels accordingly. According to the present invention, if the cumulative average load ratio is less than or equal to a predetermined threshold value, the luminance can be improved by appropriately raising the power consumption level within a range that does not substantially add a load to the display panel. At this time, when the increased power consumption level may cause the reliability of the product to deteriorate, that is, when the cumulative average load rate exceeds a predetermined threshold, the power consumption level is restored.

Therefore, high quality of the display panel can be realized while maintaining the reliability of the display panel product.

The invention is not limited to the examples described above and represented in the drawings. Those skilled in the art taught by the above-described embodiments, many modifications to the above-described embodiments are possible by substitution, erasure, merging, etc. within the scope and object of the present invention described in the following claims.

Claims (7)

A display panel driving method comprising controlling power consumption according to a cumulative average load ratio obtained by accumulating and loading load rates of two or more frames. The method of claim 1, And controlling the power consumption by selecting one of two or more power consumption control reference curves according to the cumulative average load ratio. The method of claim 2, A display panel for determining whether the cumulative average load ratio belongs to an area divided by one or more threshold values, and selecting one of the power consumption control reference curves for the number of the divided areas to perform power consumption control; Driving method. The method of claim 1, Detecting a load rate per frame from the input image data; Calculating the cumulative average load ratio; Selecting one of two or more power consumption control levels according to the cumulative average load ratio; And And determining the number of sustain pulses according to the selected power consumption control level. A load rate detector for detecting a load rate per frame from the input image data; A cumulative average load ratio calculating unit for calculating an average cumulative average load ratio by accumulating load rates of two or more frames; A storage unit storing two or more levels of power consumption control reference tables; A selection unit for selecting one of the two or more reference tables according to the cumulative average load ratio; And And a holding pulse number setting unit configured to determine the number of holding pulses according to the selected reference table. The method of claim 5, wherein the selection unit, And determining whether the cumulative average load ratio belongs to an area divided by one or more threshold values, and selecting one of the power consumption control reference tables as many as the number of the divided areas stored in the storage unit. Device. A recording medium having recorded thereon a program for executing the method of any one of claims 1 to 4 on a computer.

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