KR100740098B1 - Plasma display device and driving method thereof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to reduce fatigue degree of eyes by adjusting the number of sustain discharge pulses according to the distance between a plasma display panel and a user. A plasma display device includes a plasma display panel(100), a driver, and a controller(200). The plasma display panel includes plural discharge cells. The driver drives the plasma display panel. The controller includes plural APC(Automatic Power Control) levels corresponding to a screen load rate of input image data and allocates sustain discharge pulses corresponding to the respective APC levels to a frame. The controller applies the APC level of a first range when a distance value between a plasma display panel and a user is smaller than a first threshold value.

Description

Plasma display device and driving method thereof {PLASMA DISPLAY DEVICE AND DRIVING METHOD THEREOF}

1 is a diagram illustrating a plasma display device according to an exemplary embodiment of the present invention.

2 is a diagram illustrating a control unit according to a first embodiment of the present invention.

3 is a diagram illustrating an APC table applied to the present invention.

4 is a diagram illustrating a control unit according to a second embodiment of the present invention.

The present invention relates to a plasma display device and a driving method thereof.

The plasma display device is a display device using a plasma display panel (PDP) that displays characters or images using plasma generated by gas discharge. In the plasma display panel, dozens to millions or more pixels (discharge cells) are arranged in a matrix form according to their size.

The display panel of the plasma display device is driven by dividing one frame into a plurality of subfields having respective weights. Light emitting cells and non-light emitting cells are selected during the address period of each subfield, and sustain discharge is performed on the light emitting cells in order to actually display an image during the sustain period. The gray level is expressed by a combination of the weights of the subfields in which the cells emit light.

In this sustain period, the luminance is determined by the number of sustain discharge pulses applied to the scan electrode and the sustain electrode, respectively. This luminance varies depending on the viewing distance of the user. That is, when the viewing distance of a person is far, the brighter the brightness, the better the emotional image quality, but if it is less than a certain distance, too bright brightness rather increases the eye fatigue to reduce the emotional image quality.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma display device and a driving method thereof capable of preventing degradation of emotional image quality when a viewing distance of a user is less than or equal to a certain distance.

According to an aspect of the present invention, a plurality of APC (Automatic Power Control) levels corresponding to a screen load ratio for a plasma display panel in which a plurality of discharge cells are formed, a driver for driving the plasma display panel, and an input image signal are provided. And a control unit for allocating a number of sustain discharge pulses corresponding to each APC level to one frame. In this case, when the distance value between the user and the plasma display panel is less than or equal to the first threshold value, the controller applies only the APC level of the first range among the plurality of APC levels.

According to another aspect of the present invention, a driving method of a plasma display device including a plurality of discharge cells and dividing and driving one frame into a plurality of subfields is provided. The driving method may include calculating a screen load ratio of image data input during the one frame, comparing a distance value between the plasma display device and a user with a threshold value, and when the distance value is greater than the threshold value, the first value; Allocating the number of sustain discharge pulses corresponding to the calculated screen load ratio among the sustain discharge pulses set from a dog to a second dog, and when the distance value is less than or equal to the threshold value, the first dog to less than the second dog. And allocating the number of sustain discharge pulses corresponding to the calculated screen load ratio among the third sustain discharge pulses.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention. Like parts are designated by like reference numerals throughout the specification.

In the present invention, the wall charge refers to a charge formed close to each electrode on the wall of the cell (eg, the dielectric layer). And the wall charge is not actually in contact with the electrode itself, but is described here as "formed", "accumulated" or "stacked" on the electrode. In addition, the wall voltage refers to the potential difference formed in the wall of the cell by the wall charge.

Now, a plasma display device and a driving method thereof according to an exemplary embodiment of the present invention will be described in detail.

First, a plasma display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIG. 1.

1 is a diagram illustrating a plasma display device according to an exemplary embodiment of the present invention.

As shown in FIG. 1, a plasma display device according to an exemplary embodiment of the present invention includes a plasma display panel 100, a controller 200, an address electrode driver 300, a scan electrode driver 400, and a sustain electrode driver 500. It includes.

The plasma display panel 100 includes a plurality of address electrodes (hereinafter referred to as "A electrodes") A1 to Am extending in the column direction, and a plurality of sustain electrodes extending in pairs with each other in the row direction (hereinafter, " X electrodes "(X1 to Xn) and scan electrodes (hereinafter referred to as" Y electrodes ") (Y1 to Yn). In general, the X electrodes X1 to Xn are formed corresponding to the respective Y electrodes Y1 to Yn, and the display for displaying images in the sustain period between the X electrodes X1 to Xn and the Y electrodes Y1 to Yn. Perform the action. The Y electrodes Y1 to Yn and the X electrodes X1 to Xn are arranged to be orthogonal to the A electrodes A1 to Am. At this time, the discharge space at the intersection of the A electrodes A1 to Am and the X and Y electrodes X1 to Xn and Y1 to Yn forms the cell 12. The structure of the plasma display panel 100 is an example, and a panel having another structure to which the driving waveform described below may be applied may also be applied to the present invention.

The controller 200 receives an image signal from the outside and outputs an A electrode driving control signal, an X electrode driving control signal, and a Y electrode driving control signal. The controller 200 divides and drives one frame into a plurality of subfields, and each subfield is composed of a reset period, an address period, and a sustain period.

The address electrode driver 300 receives an A electrode driving control signal from the controller 200 and applies a display data signal for selecting a discharge cell to be displayed to each A electrode.

The scan electrode driver 400 receives a Y electrode driving control signal from the controller 200 and applies a driving voltage to the Y electrode.

The sustain electrode driver 500 receives the X electrode driving control signal from the controller 200 and applies a driving voltage to the X electrode.

FIG. 2 is a diagram illustrating the control unit shown in FIG. 1, and FIG. 3 is a diagram illustrating an APC table applied to the present invention.

As shown in FIG. 2, the control unit includes an inverse gamma correction unit 210, an error diffusion unit 220, a subfield data generation unit 230, a distance information calculation unit 240, and an automatic power control unit. 250) and sustain discharge pulse generator 260. The " APC unit "

The inverse gamma correction unit 210 performs inverse gamma correction on R (Red), G (Green), and B (Blue) image data to fit the plasma display panel 100.

The error diffusion unit 220 increases the expressive power of the gray level by diffusing some bits of the image data corrected by the inverse gamma correction unit 210 to adjacent pixels. In this case, when the input image data corresponds to the characteristics of the plasma display panel 100, the inverse gamma correction unit 210 may be removed. When the input image data does not need to spread some bits of the image data, the error diffusion unit ( 220 may be removed.

The subfield data generator 230 maps the image data output from the error diffusion unit 220 into the subfield data, and then transfers the mapped subfield data to the address electrode driver 300. Here, the subfield data is data indicating whether or not the discharge cells corresponding to the image data are turned on in the plurality of subfields. For example, one frame consists of eight subfields SF1 to SF8 having weights of 1, 2, 4, 8, 16, 32, 64, and 128, respectively, and the discharge cells represent 19 gray levels out of 0 to 255 gray levels. In this case, the subfield data of the corresponding discharge cell is "11001000" in the order of the subfields SF1 to SF8. Here, '1' indicates that the discharge cell is turned on in the corresponding subfield, and '0' indicates that the discharge cell is not turned on in the corresponding subfield.

The distance value calculator 240 calculates a distance value between the user and the plasma display panel 100 and outputs the distance value to the APC unit 250. In this case, when the user uses the remote controller, the distance between the remote controller and the plasma display panel 100 may be automatically input through a sensor or a distance value may be directly input by the user.

The APC unit 250 detects the screen load ratio from the image data output from the error diffusion unit 420 and calculates an APC level according to the detected screen load ratio. The number of sustain discharge pulses corresponding to the APC level is allocated and output to the sustain discharge pulse generator 260. In this case, the APC unit 250 applies some of the APC levels among the plurality of APC levels according to the distance values input from the distance value calculator 240.

Specifically, when the distance value input from the distance value calculator 240 does not correspond to the near mode 1, the APC unit 250 applies a plurality of APC levels (0 to 255), and the input distance value is near. In the case of mode 1, only some APC levels 10 to 255 of the plurality of APC levels 0 to 255 are applied. At this time, when the screen load ratio corresponds to the plurality of APC levels 1 to 9, the number of sustain discharge pulses corresponding to the APC level 11 is all assigned. You can also divide the near-field mode into more than one detail. That is, when the input distance value corresponds to the near mode 1, if only some APC levels 10 to 255 of the plurality of APC levels 0 to 255 are applied, the range value smaller than the close mode 2 corresponds to the plurality of APC levels. Only some of the APC levels 45 to 255 of the APC levels 0 to 255 may be applied. Here, the short range mode 1 corresponds to the case where the input distance value is smaller than the first threshold value, and the short range mode 2 corresponds to the case where the input distance value is smaller than the second threshold value smaller than the first threshold value.

That is, when the distance value input from the distance value calculator 240 does not correspond to the near field mode 1, the number of sustain discharge pulses may be set from a maximum of 1020 to at least 150 corresponding to the detected screen load ratio. When the distance value input from the value calculator 240 corresponds to the short range mode 1, the number of sustain discharge pulses may be set up to 986 to 150 in correspondence to the detected screen load ratio. In addition, when the distance value input from the distance value calculator 240 corresponds to the short range mode 2, the number of sustain discharge pulses may be set up to 866 to 150 in correspondence to the input screen load ratio. As the distance between the user and the plasma display panel 100 increases, the maximum number of sustain discharge pulses allocated to the user decreases, thereby reducing eye fatigue.

In this case, as shown in Equation 1, the screen load ratio may be calculated as an average signal level ASL of an image signal input for one frame.

,

,

은 각각 R, G, B 영상 데이터의 계조 레벨이며,

는 한 프레임이며,

은 한 프레임동안 입력된 R, G, B 영상 데이터의 데이터 개수이다.here,

,

,

Are the gradation levels of R, G, and B image data, respectively.

Is one frame,

Is the number of data of R, G, B image data input during one frame.

The sustain discharge pulse generator 260 generates a predetermined number of sustain discharge pulses from the APC unit 250 and outputs them to the scan electrodes and the sustain electrode drivers 400 and 500.

On the other hand, as shown in Fig. 4, the screen load ratio may be obtained from the subfield data. That is, the APC unit 250 'calculates the number of cells to be turned on for each subfield from the subfield data of the image data obtained by the subfield data generator 230, and calculates the number of cells to be turned on for each subfield. The screen load ratio of the image data input for one frame may be detected by multiplying the weight of each subfield.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

According to the present invention, by adjusting the brightness according to the viewing distance, eye fatigue is reduced, thereby preventing the degradation of the emotional image quality.

Claims (9)

A plasma display panel in which a plurality of discharge cells are formed; A driving unit driving the plasma display panel; It includes a plurality of APC (Automatic Power Control) level corresponding to the screen load ratio for the input image data, and a control unit for allocating a number of sustain discharge pulses corresponding to each APC level in one frame, The control unit, And applying only an APC level of a first range of the plurality of APC levels when a distance value between a user and the plasma display panel is equal to or less than a first threshold value. The method of claim 1, The control unit, And applying only an APC level of a second range narrower than the first range among the plurality of APC levels when the distance value is less than or equal to a second threshold value smaller than the first threshold value. The method of claim 2, The maximum number of the sustain discharge pulses set at the APC level of the first range is smaller than the maximum number of the sustain discharge pulses set at the plurality of APC levels, And a maximum number of sustain discharge pulses set at the APC level of the second range is smaller than a maximum number of sustain discharge pulses set at the APC level of the first range. The method of claim 3, Each of the APC levels of the first and second ranges includes an APC level corresponding to a minimum number of sustain discharge pulses. The method according to any one of claims 1 to 4, The control unit, When the screen load ratio is not included in the APC level of the first range when the distance value is smaller than the first threshold value, the number of sustain discharge pulses corresponds to any one APC level of the APC level of the first range. Plasma display device to assign. The method of claim 5, Wherein the one APC level is an APC level corresponding to the maximum number of sustain discharge pulses among the APC levels of the first range. A driving method of a plasma display device including a plurality of discharge cells and driving one frame into a plurality of subfields. Calculating a screen load ratio of the image data input during the one frame; Comparing the distance value between the plasma display device and the user with a threshold value; Allocating the number of sustain discharge pulses corresponding to the calculated screen load ratio among first to second set sustain discharge pulses when the distance value is greater than the threshold value, and Allocating the number of sustain discharge pulses corresponding to the calculated screen load ratio among the sustain discharge pulses set from the first dog to the third dog smaller than the second dog when the distance value is less than or equal to the threshold value. Method of driving a plasma display device comprising a. The method of claim 7, wherein And the screen load ratio is detected from an average signal level of image data input during the one frame. The method of claim 7, wherein And the screen load ratio is detected from subfield data of image data input during the one frame.

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