KR20050040386A - Driving method and apparatus of plasma display panel - Google Patents

Abstract

The present invention relates to a plasma display panel driving method and apparatus which can reduce driving stress by lowering the automatic power control level in a screen saver mode of a plasma display panel used as a PC monitor. In the plasma display panel driving method according to the present invention, for a plasma display panel used as a monitor of a personal computer, there are a plurality of sub-fields for time division gray scale display for each frame as a display period, and each sub-field A sustain period in the frame, comprising a reset period, an address period, and a sustain discharge period, in which sustain pulses are alternately applied to all discharge cells to generate sustain discharge in the selected discharge cells in the address period. Automatic power control is performed according to the automatic power control level inversely proportional to the load ratio, which is the ratio of the number of discharge cells to be displayed to the total discharge cells, and is stored in advance when the image signal input from the outside is a still image signal. Plasma display to display protected images on screen A method of driving a panel, the method comprising: (a) generating a still image signal when an image input from the outside is a still image; And (b) lowering the brightness of the displayed image when displaying the screen protection image on the screen according to the still image signal.

Description

Plasma display panel driving method and apparatus {Driving method and apparatus of plasma display panel}

The present invention relates to a method for driving a plasma display panel, and more particularly, in a screen saver mode of a plasma display panel used as a PC monitor, to reduce the stress of the driving unit by lowering the automatic power control (APC) level. The present invention relates to a plasma display panel driving method capable of preventing a shortened life.

1 is a perspective view showing an internal structure of a conventional three-electrode surface discharge plasma display panel. FIG. 2 is a cross-sectional view illustrating a configuration of a unit display cell of the panel of FIG. 1.

Referring to the drawings, between the front and rear glass substrates 10 and 13 of the conventional surface discharge plasma display panel 1, the address electrode lines A _R1 , A _G1 , ..., A _Gm , A _Bm ), Dielectric layers 11 and 15, Y electrode lines (Y ₁ , ..., Y _n ), X electrode lines (X ₁ , ..., X _n ), fluorescent layer 16, partition wall 17 ) And a magnesium monoxide (MgO) layer 12 as a protective layer.

The address electrode lines A _R1 , A _G1 ,..., A _Gm , A _Bm are formed in a predetermined pattern on the front side of the rear glass substrate 13. The lower dielectric layer 15 is entirely applied in front of the address electrode lines A _R1 , A _G1 ,..., A _Gm , A _Bm . In front of the lower dielectric layer 15, barrier ribs 17 are formed in a direction parallel to the address electrode lines A _R1 , A _G1 ,..., A _Gm , A _Bm . These partitions 17 function to partition the discharge area of each discharge cell and to prevent optical cross talk between each discharge cell. The fluorescent layer 16 is formed between the partition walls 17.

The X electrode lines (X ₁ , ..., X _n ) and the Y electrode lines (Y ₁ , ..., Y _n ) are the address electrode lines (A _R1 , A _G1 , ..., A _Gm , A _Bm ) is formed in a predetermined pattern on the back of the front glass substrate 10 to be orthogonal to each other. Each intersection sets a corresponding discharge cell. Each X electrode line (X ₁ , ..., X _n ) and each Y electrode line (Y ₁ , ..., Y _n ) have a conductivity and a transparent electrode line made of a transparent conductive material such as indium tin oxide (ITO). Metal electrode lines for heightening are formed in combination. The front dielectric layer 11 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 12 for protecting the panel 1 from a strong electric field, for example, a magnesium monoxide (MgO) layer, is formed by applying the entire surface to the back of the front dielectric layer 11. The plasma forming gas is sealed in the discharge space 14.

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

3 is a block diagram illustrating a conventional driving device of the plasma display panel of FIG. 1.

A typical driving device 2 of the plasma display panel 1 includes an image processor 26, a logic controller 22, an address driver 23, an X driver 24, and a Y driver 25. The image processing unit 26 converts an external analog image signal into a digital signal, for example, an internal image signal, for example, 8-bit red (R), green (G), and blue (B) image data, a clock signal, vertical and horizontal, respectively. Generate synchronization signals. The logic controller 22 generates driving control signals S _A , S _Y , and S _X according to an internal image signal from the image processor 26.

In this case, the driving unit such as the address driver 23, the X driver 24, and the Y driver 25 receives input from the driving control signals S _A , S _Y , and S _X , and generates respective driving signals. The applied driving signal to each of the electrode lines.

That is, the address driver 23 processes the address signal S _A among the drive control signals S _A , S _Y , and S _X from the logic controller 22 to generate a display data signal, and generates the displayed display. The data signal is applied to the address electrode lines. The X driver 24 processes the X driving control signal S _X among the driving control signals S _A , S _Y , and S _X from the logic controller 22 and applies the X driving control signal S _X to the X electrode lines. The Y driver 25 processes the Y driving control signal S _Y among the driving control signals S _A , S _Y , and S _X from the logic controller 22 and applies the Y driving control signal S _Y to the Y electrode lines.

4 is a timing diagram illustrating a conventional driving method of the plasma display panel of FIG. 1.

Referring to the drawing, a unit frame is divided into eight subfields SF1, ..., SF8 to realize time division gray scale display. Each subfield SF1, ..., SF8 is divided into a reset period (not shown), an address period A1, ..., A8, and a sustain discharge period S1, ..., S8. do.

The luminance of the plasma display panel is proportional to the length of the sustain discharge cycles S1, ..., S8 occupied in the unit frame. The lengths of the sustain discharge cycles S1, ..., S8 occupy a unit frame are 255T (T is the unit time). At this time, a time corresponding to 2n is set in the sustain discharge period Sn of the nth subfield SFn. Accordingly, when the subfield to be displayed among the eight subfields is appropriately selected, it can be seen that display of 256 gray levels can be performed including all zero (zero) gray levels that are not displayed in any of the subfields.

FIG. 5 is a timing diagram illustrating driving signals applied to electrode lines of the plasma display panel of FIG. 1 in a unit sub-field of FIG. 4.

In FIG. 5, reference numeral S _{AR1 ..ABm} denotes a driving signal applied to each address electrode line (A _R1 , A _G1 ,..., A _Gm , A _{Bm in} FIG. 1), and S _{X1 .. Xn} denotes an X electrode. Drive signal applied to the lines (X ₁ , ..., X _n of FIG. 1), and S _{Y1 ..Yn} is applied to each Y electrode line (Y ₁ , ..., Y _n of FIG. 1). Indicates a driving signal.

Referring to the drawing, in the reset period PR of the unit sub-field SF, first, the voltage applied to the X electrode lines X ₁ ,..., X _n is set from the ground voltage V _G to the second. for the voltage (V _S) for example, then continue to rise to 155 volts (V). Here, the ground voltage V _G is applied to the Y electrode lines Y ₁ ,..., Y _n and the address electrode lines A _R1 , A _G1 ,..., A _Gm , A _Bm .

Next, the voltage applied to the Y electrode lines Y ₁ ,..., Y _n is third from the second voltage V _S , for example, from 155 volts V to a second voltage than the second voltage V _S. The highest voltage V _SET + V _{S that} is as high as the voltage V _SET is continuously raised to, for example, 355 volts (V). Here, the ground voltage V _G is applied to the X electrode lines X ₁ ,..., X _n and the address electrode lines A _R1 , A _G1 ,..., A _Gm , A _Bm .

Next, in the state where the voltage applied to the X electrode lines X ₁ ,..., X _n is maintained at the second voltage V _S , the Y electrode lines Y ₁ ,..., Y _n The voltage applied to) is continuously lowered from the second voltage V _S to the ground voltage V _G. Here, the ground voltage V _G is applied to the address electrode lines A _R1 , A _G1 ,..., A _Gm , and A _Bm .

Accordingly, in the address period (PA), leading address is applied to a display data signal to the electrode lines, the the second voltage (V _S) lower fourth voltage (V _SCAN) to bias the Y-electrode line than the (Y ₁ As a scan signal of the ground voltage V _G is sequentially applied to the ..., Y _n ), smooth addressing may be performed. The display data signal applied to each of the address electrode lines A _R1 , A _G1 , ..., A _Gm , A _Bm has a positive address voltage V _A when the discharge cell is selected, and a ground voltage when the discharge cell is not. (V _G ) is applied. Accordingly, when the display data signal of the positive address voltage V _A is applied while the scan pulse of the ground voltage V _G is applied, wall charges are formed by the address discharge in the corresponding discharge cell. Wall charges do not form. Here, for more accurate and efficient address discharge, the second voltage V _S is applied to the X electrode lines X ₁ ,..., X _n .

In the sustain discharge period PS that follows, the second voltage V _S is applied to all of the Y electrode lines Y ₁ , ..., Y _n and the X electrode lines X ₁ , ..., X _n . The display sustain pulse is alternately applied, causing a discharge for display retention in the discharge cells in which wall charges are formed in the corresponding address period PA.

6 is a graph schematically illustrating the principle of automatic power control in a conventional plasma display panel.

Referring to the drawings, in general, according to Automatic Power Control (APC), the ratio of the discharge cells that are turned on (ON) of the discharge cells of the entire screen, the sustain electrode in the sustain discharge period in one frame according to the load ratio Control the number of sustain pulses applied to the line pairs. At this time, the number of sustain pulses in the unit frame is inversely related to the load ratio.

In other words, if the load ratio is small, the number of sustain pulses in the unit frame is increased to increase the brightness of the displayed image. If the load ratio is large, power consumption can be reduced by reducing the number of sustain pulses in the unit frame. In the example of the figure, when the load ratio is L1, the number of sustain pulses in the unit frame becomes N1. When the load ratio decreases to L2, the number of sustain pulses in the unit frame increases to N2, and when the load ratio reaches L4. The number of sustain pulses in the unit frame becomes N4, and the number of sustain pulses in the unit frame has an inverse relationship with the load factor.

In addition, when a still image without a change in image signal is input for a predetermined time in a plasma display panel used as a monitor of a personal computer (PC), a screen saver mode is entered according to user's setting to protect screen and consume power. Will be lowered.

In this case, the screen saver mode of the plasma display panel has a low load rate to be close to the minimum load rate. Therefore, when the plasma display panel is driven by the automatic power control (APC), the number of sustain pulses in the unit frame is close to the maximum, thereby causing a large stress and sleep deterioration in the driving circuit unit and the panel.

The present invention is to solve the above problems, in the screen saver mode of the plasma display panel used as a PC monitor, by reducing the level of the automatic power control (Automatic Power Control (APC)) to reduce the stress of the drive unit and the resulting lifetime An object of the present invention is to provide a plasma display panel driving method capable of preventing shortening.

In the plasma display panel driving method according to the present invention for achieving the above object, there is a plurality of sub-fields for time division gray scale display for each frame as the display period for the plasma display panel used as a monitor of a personal computer Each sub-field has a reset period, an address period, and sustain discharge periods, and sustain pulses alternately applied to all discharge cells are applied to the sustain discharge period to generate sustain discharge in the discharge cells selected in the address period. Automatic power control is performed according to an automatic power control level in which the number of sustain pulses in the frame is inversely proportional to the load ratio, which is the ratio of the number of discharge cells to be displayed for all the discharge cells, and the image signal input from the outside is stopped. In case of video signal In the driving method of the plasma display panel shown in, (a) generating a still image signal when the image is a still image input from the outside; And (b) lowering the brightness of the displayed image when displaying the screen protection image on the screen according to the still image signal.

In the step (a), (a1) determining whether the image input from the outside is a still image and detecting a still image; and (a2) if the image input from the outside is a still image, It is preferred to have a step of producing.

In the step (a1), when there is no key input of the personal computer for a time longer than a preset reference time, it is preferable to determine the image input from the outside as a still image.

In the step (b), it is preferable to reduce the brightness of the screen by reducing the number of sustain pulses in the frame.

At this time, it is preferable to reduce the number of sustain pulses in the frame by lowering the automatic power control level according to the still image signal from the step (a).

In the plasma display panel driving apparatus according to another aspect of the present invention, for a plasma display panel used as a monitor of a personal computer, there are a plurality of sub-fields for time division gray scale display for each frame as a display period, and each sub- The field has a reset period, an address period, and a sustain discharge period, and sustain pulses alternated to all discharge cells are applied to the sustain discharge period to generate sustain discharge in the discharge cells selected in the address period. Automatic power control is performed in accordance with the automatic power control level inversely proportional to the load ratio, which is the ratio of the number of discharge cells to be displayed to the total discharge cells, and in advance when the image signal input from the outside is a still image signal. Plasma D displaying the saved screen protection image on the screen In the driving device of the play panel, still image sensing unit for generating a still image signal when the image input from the outside of the still image; And a brightness controller which lowers the brightness of the displayed image when displaying the screen protection image on the screen according to the still image signal.

The still image detector may be configured to determine whether an image input from the outside is a still image and to detect a still image, and a still image signal to generate a still image signal when the external image is a still image. It is preferable to have a generation part.

According to the present invention, in the screen saver mode of a plasma display panel used as a monitor of a PC, an automatic power control (APC) level is reduced to reduce driving stress, thereby preventing a shortening of the lifetime of the plasma display panel. can do.

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

7 is a flowchart schematically illustrating a method of driving a plasma display panel according to an exemplary embodiment of the present invention. FIG. 8 is a flowchart schematically illustrating a method of displaying a still image by the plasma display panel driving method of FIG. 7. FIG. 9 is a block diagram schematically illustrating a plasma display panel driving apparatus for implementing the method of driving the plasma display panel of FIG. 7.

Referring to the drawings, the plasma display panel driving method 100 includes a plurality of sub-fields for time division grayscale display for each frame as a display period for a plasma display panel used as a monitor of a personal computer (Figs. 4 and 5). SFs are present, and each sub-field SF has a reset period (PR in FIG. 5), an address period (PA in FIG. 5), and a sustain discharge period (PS in FIG. 5), and a sustain discharge period. Alternate sustain pulses are applied to all the discharge cells to generate sustain discharge in the discharge cells selected in the address period PA, and the number of sustain pulses in the frame is to be displayed among all the discharge cells. Automatic power control is performed according to the automatic power control level inversely proportional to the load ratio, which is the ratio of the number of cells, and stored in advance when the externally input video signal is a still image signal. A method of driving a plasma display panel for displaying a surface protection image on a screen, the method comprising: (a) generating a still image signal when the image input from the outside is a still image (S101, S102); And (b) lowering the brightness of the displayed image (S103, S104) when displaying the screen protection image on the screen according to the still image signal.

In the step (a), (a1) determining whether the image input from the outside is a still image and detecting a still image (S101); and (a2) the still image when the image input from the outside is a still image. It is preferable to have a step (S102) for generating a signal.

At this time, in the step (a1) (S101), when there is no key input of the personal computer for a time longer than the preset reference time, it is preferable to determine the image input from the outside as a still image.

In step (b) (S103, S104), it is preferable to reduce the brightness of the screen by reducing the number of sustain pulses in the frame. At this time, it is preferable to reduce the number of sustain pulses in the frame by lowering the automatic power control level according to the still image signal from the step (a).

In the driving method 100 of the plasma display panel, there are a plurality of sub-fields SF for time division gray scale display for each frame as a display period. In addition, each sub-field SF has a reset period PR, an address period PA, and a sustain discharge period PS.

In the present embodiment, in the reset period PR, a rising ramp pulse is applied to the Y electrode lines while maintaining the address voltage applied to the address electrode lines as the reference voltage V _G as shown in FIG. 5. And discharge ramp pulses are sequentially applied to initialize all discharge cells.

As the scan signal of the ground voltage V _G is sequentially applied to the Y electrode lines Y ₁ ,..., Y _n biased with the scan voltage V _{SCAN in} the address period PA, respectively. The display data signal is applied to each of the address electrode lines of the discharge cells to be displayed with respect to the scan signal of and the address discharge is generated only in the discharge cells to be displayed to form wall charges in the discharge cells to be displayed.

In the sustain discharge period PS that follows, the second voltage V _S is applied to all of the Y electrode lines Y ₁ , ..., Y _n and the X electrode lines X ₁ , ..., X _n . The display sustain pulse is alternately applied, causing a discharge for display retention in the discharge cells in which wall charges are formed in the corresponding address period PA.

In this case, the luminance of the plasma display panel is proportional to the length of the sustain discharge period (S1, ..., S8 in FIG. 4), that is, the number of sustain pulses occupied in the unit frame. In addition, in the present embodiment, the power consumption is controlled by an automatic power control (APC). Automatic power control (APC) controls the number of sustain pulses in each frame to be inversely proportional to the load rate, where the load rate is the ratio of the number of discharge cells to be displayed among the total discharge cells.

In addition, the image board 36 detects an image signal input from the outside, and when there is no image signal input from the outside, the microcomputer of the image board 36 displays the screen protection image stored in the memory in advance on the screen. At this time, in the case of controlling the driving of the panel by the normal automatic power control (APC), the portion displayed on the entire screen is small, the load ratio is small, and the number of sustain pulses in the unit frame is large.

In order to solve this problem, the method 100 for driving a plasma display panel includes (a) steps S101 and S102, and (b) steps S103 and S104. S102 generates a still image signal when the image input from the outside is a still image, and in step (b) (S103, S104) when displaying a screen protection image on the screen according to the still image signal, Lower the brightness of the displayed image.

(A) Steps S101 and S102 for generating still image signals when the image input from the outside is a still image include steps a101 and S102. In the step (a1), it is determined whether the image input from the outside is a still image, and in step (a2), the still image is detected when the image input from the outside is the still image. Generate a signal.

In the detecting of the still image (S101), as illustrated in FIG. 8, the pattern of the currently input image signal is recognized (S201), and it is determined whether the same image signal is still according to whether the same image signal is maintained for a predetermined time (S202). You will be able to detect still images.

In this case, when the same image signal is maintained for a predetermined time or more, the image is recognized as a still image and displayed in advance in the memory (S203). Otherwise, the input image is displayed (S204).

In the detecting of the still image (S101), an input image signal may be compared frame by frame, and image signals of the previous frame and the current frame may be compared to detect whether the still image is the same. In this case, whether the still image is the same may be determined as the still image when the same image signal is the same as the preset image signal of a predetermined number of consecutive frames. That is, when the number of video signals of consecutive frames corresponding to a predetermined time is the same, it may be determined as a still picture.

At this time, in the step (a1) (S101), if there is no key input of the personal computer for a time longer than the preset reference time, the image input from the outside may be determined as the still image.

Therefore, when the input video signal is the same for the number of consecutive frames corresponding to a predetermined time, and there is no key input by the keyboard of the personal computer for a predetermined time, the input image from the outside is judged as a still image, If the signal changes or there is a key input, it may be determined that the image is not a still image.

In particular, the image signal input from the outside by not only key input by a keyboard but also input from various input devices of a personal computer may be recognized as not a still image.

In the step (b) (S103, S104) of lowering the brightness of the image displayed according to the still image signal, when the still image signal is input, it is determined that the image signal input from the outside is a still image (S103). In this case, a screen protection image stored in memory in advance is displayed on the screen. In this case, when the screen protection image is displayed, the automatic power control (APC) level is lowered (S104) to lower the brightness of the displayed screen so as to reduce the stress of the driving unit.

That is, in the case of automatic power control (APC), the number of sustain pulses in a frame is controlled in inverse proportion to the load ratio. In this case, the load ratio is a ratio of discharge cells to be displayed with respect to all discharge cells. In addition, in the case of the screen protection image, the load factor is low, the number of sustain pulses in the unit frame is large, and power consumption is high, and stress on the driving unit is severe.

Therefore, according to the present invention, it is desirable to reduce the power consumption by reducing the number of sustain pulses by lowering the automatic power control (APC) level for the still image, and to reduce the stress of the driving unit. In general, the screen protection image is not a screen for the purpose of transmitting information, but is to prevent a permanent image that may be formed on the screen after a still image lasts for a predetermined time, and the brightness of the screen is not important. This is because even if the luminance of S decreases slightly, it does not matter.

Therefore, in the step (b) (S103, S104), according to the still image signal from the step (a), the automatic power control level is lowered to reduce the number of sustain pulses in the frame, thereby reducing the brightness of the screen. Lower.

The still image detecting unit 371 of FIG. 9 performs step (a), and detects a still image (S101) and generates a still image signal (S102). As shown in FIG. It may be, but may be configured to be included in the image processor 36. In addition, the functions of determining the still image signal (S103) and lowering the automatic power control level (S104) may be processed in the logic controller 32.

Here, the driving device of the plasma display panel shown in FIG. 9 is for implementing the driving method of the plasma display panel shown in FIG. 7 and the same components as the driving device of the plasma display panel shown in FIG. 3 are specifically mentioned. Except for one matter, they have the same function as shown in FIG.

FIG. 10 is a block diagram schematically illustrating a logic controller of the plasma display panel driver of FIG. 9.

Referring to the drawings, the driving controller 42 according to the present invention includes a clock buffer 45, a synchronization controller 426, a gamma correction unit 41, an error diffusion unit 412, and first-in first-out. ) Memory 411, Subfield Generator 421, Subfield Matrix 422, Matrix Buffer 423, Memory Controller 424, Frame-Memorys RFM1, ..., BFM3, Cultivation Thermal section 425, average signal level detection section 43a, power control section 43, EPIROM 44a, I ² C serial communication interface 44b, timing-signal generator 44c, and XY control section 44 ).

The clock buffer 45 converts the 26-megahertz (MHz) clock signal CLK26 from the image processor (36 in FIG. 8) into a 40-megahertz (MHz) clock signal CLK40 and outputs the converted signal. The synchronization adjusting unit 426 includes a clock signal CLK40 of 40 mega-hertz (MHz) from the clock buffer 45, an initialization signal RS from the outside, and a horizontal synchronization signal from the image processing unit (36 in FIG. 8). (H _SYNC ) and the vertical sync signal V _SYNC are input. The synchronization adjusting unit 426 outputs the horizontal synchronization signals H _SYNC1 , H _SYNC2 , and H _SYNC3 to which the input horizontal synchronization signal H _SYNC is delayed by a predetermined number of clocks, respectively. V _SYNC ) outputs vertical synchronization signals V _SYNC2 and V _SYNC3 delayed by a predetermined number of clocks, respectively.

The image data R, G, and B input to the gamma correction unit 41 have reverse nonlinear input / output characteristics in order to correct the nonlinear input / output characteristics of the cathode ray tube. Therefore, the gamma correction unit 41 processes the image data R, G, and B of the reverse nonlinear input and output characteristics to have a linear input and output characteristic. The error diffusion unit 412 reduces the data transmission error by using the first-in first-out memory 411 to move the position of the maximum sign bit, which is the boundary bit of the image data R, G, and B. FIG.

The subfield generator 421 converts the 8-bit image data R, G, and B into image data R, G, and B of the bit number corresponding to the number of subfields, respectively. For example, when grayscale driving is performed with 14 subfields in a unit frame, after converting 8-bit image data R, G, and B into 14-bit image data R, G and B, respectively, In order to reduce a data transmission error, 16 bits of image data R, G, and B are output by adding invalid data '0' of a maximum value bit (MSB) and a minimum value bit (Least Significant Bit).

The subfield matrix unit 422 rearranges 16-bit video data R, G, and B into which data of different subfields is simultaneously input, so that data of the same subfield is simultaneously output. The matrix buffer unit 423 processes the 16-bit image data (R, G, B) from the subfield matrix unit 422 and outputs it as 32-bit image data (R, G, B).

The memory controller 424 may include a red memory controller for controlling three red frame R memories (RFM1, RFM2, and RFM3), three green (G) frame memory memories (GFM1, GFM2, A green memory control unit for controlling GFM3) and a blue memory control unit for controlling the three blue frame B memories (BFM1, BFM2, BFM3). The frame data from the memory controller 424 is continuously output in units of frames and input to the rearrangement unit 425. In the drawing, reference numeral EN denotes an enable signal generated from the XY controller 44 and input to the memory controller 424 to control the data output of the memory controller 424. In addition, the reference numeral S _SYNC is generated from the XY control unit 44 to control data input / output in units of 32-bit slots in the memory control unit 424 and the rearrangement unit 425. The slot synchronization signal input to 425 is indicated. The rearrangement unit 425 rearranges and outputs 32-bit image data R, G, and B from the memory control unit 424 in accordance with the input format of the address driver (33 in FIG. 8).

On the other hand, the average signal level detector 43a detects the average signal-level ASL in units of frames from the 8-bit image data R, G, and B from the error diffusion unit 412, respectively, so that the power controller 43 To enter. The power control section 43 generates the number of discharge control data APC corresponding to the average signal-level ASL input from the average signal level detection section 43a, thereby making automatic power consumption constant in each frame. Perform the function of control. Here, the load rate means the average load rate of the load rates of each subfield of the frame. The load ratio of each subfield means a ratio of the number of cells to be displayed to the number of all cells of the plasma display panel 1. In the present embodiment, the power control unit 43 performs the automatic power control function when the load ratio of the frame exceeds 30%. In the YEPROM 44a, the X electrode lines (X ₁ , ..., X _n of FIG. 1) and the Y electrode lines (Y ₁ , ..., Y _{n of} FIG. Timing control data is stored. The discharge recovery control data APC from the power control unit 43 and the timing control data from EPIROM 44a are input to the timing-signal generator 44c through the I ² C serial communication interface 44b. The timing-signal generator 44c operates according to the input discharge count control data APC and the timing control data to generate a timing-signal. The XY control unit 44 operates in accordance with the timing-signal from the timing-signal generator 44c to output the X drive control signal S _X and the Y drive control signal S _Y.

At this time, when the still image signal is generated in the step of generating a still image signal (S102), the still image signal is input to the power control unit 43, the automatic power control unit 43 in the power control unit 43 in the still image signal In step S103, the automatic power control level may be lowered when the still image signal is input (S104).

FIG. 11 is a graph schematically illustrating automatic power control level adjustment by the method of driving the plasma display panel of FIG. 7. FIG. 12 is a graph schematically illustrating a change in power consumption according to the automatic power control level adjustment of FIG. 11.

Referring to the drawings, the principle of automatic power control operation in the power control section 43 of FIG. 10 is based on the drive-characteristic graph as shown. The curve A is a discharge recovery control data (APC) curve before the still image signal is reflected according to the present invention, and the curve B is a discharge recovery control data (APC) curve by the driving method of the plasma display panel according to the present invention.

A process of generating the drive-characteristic graph using the A curve as an example is as follows. First, the characteristics of the load factor and power are determined while varying the number of display-discharge times Ns in a unit frame. Next, the load ratios L4, L3, L2, and L1 forming the reference electric power amount are obtained for each display-discharge number Ns. The lowest display-discharge count is set at a load rate of 100 percent (%). By this principle, power control is performed as follows based on the load ratios L4, L3, L2, and L1.

From 0 to L4, the highest indication-discharge count (N4) applies. In the range where the load factor is higher than L4 and below L3, the second highest indication-discharge number N3 is applied. The third highest indication-discharge count (N2) applies where the load factor is above L3 and below L2. If the load factor is higher than L2, the lowest indication-discharge number N1 is applied. Here, the load rate L1 indicates a load rate of 100 percent (%) in which all discharge cells perform display discharge.

When the intersection points P1, P2, P3, and P4 of the number of sustain pulses corresponding to the load ratio are connected to each other, a driving characteristic curve can be obtained. The display-discharge number Ns and the load ratio can be appropriately selected within a range not departing from such driving characteristics.

In the method of driving a plasma display panel according to the present invention, when a still image signal is input, the discharge count control data is generated according to the B curve by lowering the level rather than the existing A curve. Therefore, it drives with the discharge count reduced with respect to the same load factor.

In this case, the number of discharges represents the number of sustain pulses per frame. According to the present invention, the number of sustain pulses for discharging by the entire subfields is the same but the number of sustain pulses is reduced by that, and the driving stress is reduced. do. In addition, power consumption can be reduced as shown in FIG.

13 is a block diagram schematically illustrating a plasma display panel driving apparatus according to another embodiment of the present invention.

Referring to the drawings, the plasma display panel driving apparatus includes a plurality of sub-fields (SFs of FIGS. 4 and 5) for time-division grayscale display for each frame as a display period for a plasma display panel used as a monitor of a personal computer. Each sub-field SF has a reset period (PR in FIG. 5), an address period (PA in FIG. 5), and a sustain discharge period (PS in FIG. 5), and a sustain discharge period PS Alternate sustain pulses are applied to all discharge cells to cause sustain discharge in the selected discharge cells in the address period PA. The number of discharge cells to be displayed among the total discharge cells is indicated by the number of sustain pulses in the frame. Automatic power control is performed according to the automatic power control level inversely proportional to the non-loading rate, and is stored in advance when the image signal input from the outside is a still image signal. An apparatus for driving a plasma display panel for displaying a protected image on a screen, the apparatus comprising: a still image detector 571; And a brightness controller 572.

The still image detecting unit 571 generates a still image signal when the image input from the outside is a still image. The brightness controller 574 lowers the brightness of the displayed image when displaying the screen protection image on the screen according to the still image signal.

In this case, the still image detector 571 may determine whether the image input from the outside is a still image, and determine whether the still image is detected, and when the image input from the outside is a still image. It is preferable to provide a still image signal generation unit 573 for generating a still image signal.

The still image determining unit 572 may determine the still image input from the outside when there is no key input of the personal computer for a time longer than a preset reference time.

The brightness controller 574 may reduce the brightness of the screen by reducing the number of sustain pulses in the frame. In this case, the brightness controller 574 may reduce the number of sustain pulses in the frame by lowering the automatic power control level according to the still image signal from the still image detector 571.

The driving apparatus of the plasma display panel according to the present embodiment is a driving apparatus for implementing the driving method of the plasma display panel of FIGS. 7 and 8, and performs the same function as the driving apparatus shown in FIGS. 9 and 10. Like reference numerals refer to like elements that perform functions, and detailed descriptions thereof will be omitted.

The image processor 56 includes an external image signal processor 561, a scaler 562, and an interface 563. The external video signal processor 561 receives an external video signal and converts the external video signal into a signal suitable for display on the plasma display panel. In this case, the external video signal may be a TV / video input signal, a PC input signal, a digital TV signal, or a digital versatile disc (DVD) input signal. The external image signal processor 561 may be configured to convert various input signals as described above to be displayed on the plasma display panel.

When a TV / video input signal is input, the video signal is processed through a video decoder, a deinterlacer, or the like. When a PC input signal is input, an analog to digital converter is used. Through the video signal can be processed. In addition, when a digital TV signal is input, the video signal may be processed through a video processor or the like, and when a DVD input signal is input, the video signal may be processed through a TMDS receiver (Time Modulation Differential Signal Receiver).

The scaler 562 scales the image signal processed by the external image signal processor 561 to data having a size appropriate to be displayed on the plasma display panel. In this case, the luminance information for each of red, green, and blue is reflected for each pixel of the panel to be displayed in the scaler 562 during data processing.

The interface 563 is to interface with the panel 1 so that the image signal processed in the image processing unit 56 can be displayed on the panel 1. As the interface 563 method, a method based on low voltage differential signaling (LVDS) or TMDS may be used.

In this case, the still image detecting unit 571 may be included in the image processing unit 56, and may be performed by a microcomputer that is connected to an external image signal processing unit 561 or an external image signal processing unit in the image processing unit 56. will be.

According to the plasma display panel driving method according to the present invention, in the screen saver mode of the plasma display panel used as a PC monitor, the automatic power control (APC) level is lowered to reduce the stress of the driving unit, and thereby the plasma It is possible to prevent shortening the life of the display panel.

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, it is merely an example, and those skilled in the art may realize various modifications and equivalent other embodiments therefrom. I can understand. Accordingly, the true scope of protection of the invention should be defined only by the appended claims.

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

FIG. 2 is a cross-sectional view illustrating a configuration of a unit display cell of the panel of FIG. 1.

3 is a block diagram illustrating a conventional driving device of the plasma display panel of FIG. 1.

4 is a timing diagram illustrating a conventional driving method of the plasma display panel of FIG. 1.

FIG. 5 is a timing diagram illustrating driving signals applied to electrode lines of the plasma display panel of FIG. 1 in a unit sub-field of FIG. 4.

6 is a graph schematically illustrating the principle of automatic power control in a conventional plasma display panel.

7 is a flowchart schematically illustrating a method of driving a plasma display panel according to an exemplary embodiment of the present invention.

FIG. 8 is a flowchart schematically illustrating a method of displaying a still image by the plasma display panel driving method of FIG. 7.

FIG. 9 is a block diagram schematically illustrating a plasma display panel driving apparatus for implementing the method of driving the plasma display panel of FIG. 7.

FIG. 10 is a block diagram schematically illustrating a logic controller of the plasma display panel driver of FIG. 9.

FIG. 11 is a graph schematically illustrating automatic power control level adjustment by the method of driving the plasma display panel of FIG. 7.

FIG. 12 is a graph schematically illustrating a change in power consumption according to the automatic power control level adjustment of FIG. 11.

13 is a block diagram schematically illustrating a plasma display panel driving apparatus according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

22, 32, 52: logic controller 26, 36, 56: image processor

371, 571: Still image detection unit 572: Still image determination unit

573: still image signal generation unit 574: brightness adjustment unit

Claims (10)

For a plasma display panel used as a monitor of a personal computer, there are a plurality of sub-fields for time division gray scale display for each frame as a display period, each sub-field being a reset period, an address period, and a sustain discharge period. And sustain pulses alternately applied to all discharge cells in the sustain discharge period to generate sustain discharge in the discharge cells selected in the address period, and the number of sustain pulses in the frame is applied to all the discharge cells. Automatic power control is performed according to an automatic power control level inversely proportional to the load ratio, which is the ratio of the number of discharge cells to be displayed. In the driving method of the plasma display panel, (a) generating a still image signal when the image input from the outside is a still image; And and (b) lowering the brightness of the displayed image when displaying the screen protection image on the screen according to the still image signal. The method of claim 1, In step (a), (a1) determining whether the image input from the outside is a still image and detecting a still image; (a2) generating a still image signal when the image input from the outside is a still image; The method of claim 2, In the step (a1), And determining that the image input from the outside is a still image when there is no key input of the personal computer for a time longer than a preset reference time. The method of claim 1, In step (b), And driving the plasma display panel to reduce the brightness of the screen by reducing the number of sustain pulses in the frame. The method of claim 4, wherein And the number of sustain pulses in the frame is reduced by lowering the automatic power control level in accordance with the still image signal from step (a). For a plasma display panel used as a monitor of a personal computer, there are a plurality of sub-fields for time division gray scale display for each frame as a display period, each sub-field being a reset period, an address period, and a sustain discharge period. And sustain pulses alternately applied to all discharge cells in the sustain discharge period to generate sustain discharge in the discharge cells selected in the address period, and the number of sustain pulses in the frame is applied to all the discharge cells. Automatic power control is performed according to an automatic power control level inversely proportional to the load ratio, which is a ratio of the number of discharge cells to be displayed, and when the image signal input from the outside is a still image signal, a previously stored screen protection image is displayed on the screen. In the driving apparatus of the plasma display panel, A still image detector generating a still image signal when the image input from the outside is a still image; And And a brightness controller which lowers the brightness of the displayed image when the screen protection image is displayed on the screen according to the still image signal. The method of claim 6, The still image detection unit, A still image determination unit detecting a still image by determining whether the image input from the outside is a still image; And a still image signal generator configured to generate a still image signal when the image input from the outside is a still image. The method of claim 7, wherein The still image determination unit, And a non-key input of the personal computer for a time longer than a preset reference time to determine the image input from the outside as a still image. The method of claim 6, The brightness control unit, And driving the plasma display panel to reduce the brightness of the screen by reducing the number of sustain pulses in the frame. The method of claim 9, And the number of sustain pulses in the frame is reduced by lowering the automatic power control level according to the still image signal from the still image detection unit.