KR100739627B1 - Plasma display and driving method thereof - Google Patents

Abstract

The plasma display device drives an image signal of one frame input into a plurality of subfields. Here, the plasma display device detects whether a video signal of one frame is a peak image, and allocates and applies a greater number of first total sustain discharge pulses than a peak image when the peak image is a peak image. When the peak image signal lasts for a predetermined time, the second total sustain discharge pulse number less than the first total sustain discharge pulse number is allocated and applied.

Sustain discharge pulse, peak image, subfield, afterimage

Description

Plasma Display and Driving Method {PLASMA DISPLAY AND DRIVING METHOD THEREOF}

1 is a schematic plan view of a plasma display device according to an exemplary embodiment of the present invention.

2 is a schematic block diagram of a controller of a plasma display device according to an exemplary embodiment of the present invention.

3 is a diagram illustrating an example of a peak image.

FIG. 4A illustrates a histogram distribution of a peak image, and FIG. 4B illustrates a distribution of a histogram of a general image.

5 is a look-up table showing the total number of sustain discharge pulses corresponding to the APC level.

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 that displays text or an image by using plasma generated by gas discharge.

Such a plasma display device divides an image signal of an input frame into a plurality of subfields and combines the subfields to express gray scales. Each subfield includes an address period and a sustain period, expressed as a temporal operation change. The address period is a period for selecting a discharge cell that is turned on and a discharge cell that is not turned on, and the sustain period is used to apply a sustain discharge pulse to perform discharge for actually displaying an image in the discharge cell set as the discharge cell to be turned on in the address period. It is a period.

On the other hand, the luminance of the plasma display device is determined by the total number of sustain discharge pulses applied in the sustain period of one frame. In addition, the plasma display device adjusts the total number of sustain discharge pulses applied to one frame according to a load ratio of an input image signal to maintain a constant power consumption. In this case, in case of a low load image, the total number of sustain discharge pulses is increased to improve luminance, but when the low load image is changed to another image after a long duration, the image sticking phenomenon of the previous frame is overlapped. This happens.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma display device and a driving method thereof for preventing afterimage phenomenon and improving luminance.

According to a feature of the present invention for achieving the above object, there is provided a driving method of a plasma display device for dividing and driving the video signal of one frame input into a plurality of subfields. The driving method includes detecting whether the image signal of the one frame is a peak image having a first gray level in a predetermined area and a second gray level lower than the first gray level in the remaining area; If the image signal of the one frame is a peak image, assigning the first total sustain discharge pulse number to the peak image more than if it is not a peak image and applying the same to the peak image; And when the peak image signal lasts for a predetermined time, allocating a second total sustain discharge pulse number less than the first total sustain discharge pulse number to the peak image and applying the same to the plasma display device. The detecting of the peak image may include detecting a distribution of a histogram of the image signal of one frame; And calculating a value of an average signal level of the image signal of the one frame. Here, when the distribution of the histogram is distributed only in the first grayscale and the second grayscale and the value of the average signal level is smaller than a predetermined value, it is determined as the peak image.

According to another feature of the present invention, a plasma display device is provided. The plasma display device includes a plasma display panel for forming a plurality of discharge cells; A controller configured to control an image signal of one input frame to be divided into a plurality of subfields; And a driving unit which drives the plasma display panel according to a control signal of the controller, wherein the controller is configured such that the image signal of the one frame has a first gray level in a predetermined area and a second area lower than the first gray level in the other area. Detecting whether the peak image has a gray level and when the image signal of one frame is the peak image, the first total sustain discharge pulse number of the total sustain discharge pulses applied to one frame is allocated to the peak image to display the plasma image. Control to apply to the panel. The controller may be configured to allocate a second total sustain discharge pulse number less than the first total sustain discharge pulse number to the peak image and apply it to the plasma display panel when the peak image signal lasts for a predetermined time. To control. The controller may be configured to, when the distribution of the histogram of the video signal of one frame is distributed only to the first gray level and the second gray level, and the value of the average signal level of the video signal of one frame is smaller than a predetermined value. Judging by the peak image.

DETAILED DESCRIPTION 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, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, except to exclude other components unless otherwise stated. In addition, the "maintenance discharge pulse" referred to throughout the specification means a waveform applied to the electrode for the sustain discharge in the sustain period, and means not only a pulse type waveform but also various types of waveforms. In addition, since one sustain discharge is generated once in the sustain period by one sustain discharge pulse, "number of sustain discharge pulses" is used to mean "number of sustain discharges" generated in the sustain period, and "total number of sustain discharge pulses" is one. The total number of sustain discharge pulses applied to the frame is used as a meaning.

1 is a schematic plan view of 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 A1 to Am extending in the column direction, and a plurality of sustain electrodes X1 to Xn and scan electrodes Y1 to Yn extending in pairs in the row direction. Include. The sustain electrodes X1 to Xn are formed corresponding to the scan electrodes Y1 to Yn, and generally, one end thereof is commonly connected to each other. The plasma display panel 100 includes a substrate (not shown) on which the sustain and scan electrodes X1 to Xn and Y1 to Yn are arranged, and a substrate (not shown) on which the address electrodes A1 to Am are arranged. The two substrates are disposed to face each other so that the scan electrodes Y1 to Yn and the address electrodes A1 to Am and the sustain electrodes X1 to Xn and the address electrodes A1 to Am are orthogonal to each other. At this time, the discharge space at the intersection of the address electrodes A1 to Am and the sustain and scan electrodes X1 to Xn and Y1 to Yn forms a discharge cell. The structure of the plasma display panel 100 is an example, and the present invention is not limited thereto, and other structures may also be applied to the present invention.

The address electrode driver 300 receives an address electrode driving control signal from the controller 200 and applies a display data signal for selecting a discharge cell to be displayed to each address electrode A1 to Am. The scan electrode driver 400 receives a scan electrode driving control signal from the controller 200 and applies a driving voltage to the scan electrodes Y1 to Yn. The sustain electrode driver 500 receives the sustain electrode driving control signal from the controller 200 and applies a driving voltage to the sustain electrodes X1 to Xn.

The controller 200 receives image signals R, G, and B data and a synchronization signal from the outside, and outputs an address electrode driving control signal, a sustain electrode driving control signal, and a scan electrode driving control signal. The controller 200 controls one frame to be divided and driven into a plurality of subfields, and each subfield includes an address period and a sustain period when expressed as a temporal change in operation. Here, the control unit 200 according to an embodiment of the present invention is to prevent the afterimage phenomenon and to improve the brightness, the input image signal (R, G, B Data) is a predetermined image (for example, shown in FIG. Peak image), and in the case of a predetermined image (peak image), separate image processing is performed to prevent afterimage phenomenon and to improve luminance.

Hereinafter, a method of preventing afterimage phenomenon and improving luminance by the controller 200 of the plasma display device according to an exemplary embodiment of the present invention will be described in detail with reference to FIGS. 2 to 5.

2 is a schematic block diagram of a controller 200 of a plasma display device according to an exemplary embodiment of the present invention.

As shown in FIG. 2, the controller 200 of the plasma display device according to the exemplary embodiment of the present invention may include a peak image detector 220, an automatic power controller 240, a peak image processor 260, and a scan and sustain electrode driving controller ( 280). In FIG. 2, only a necessary configuration for preventing afterimages and improving luminance of the peak image is shown. Other components, such as a configuration for generating subfield data and generating address data, are omitted for convenience of description.

The peak image detector 220 determines whether the input image signal is an image in which only a predetermined area of the entire screen is a bright image and the remaining portion is a dark gray image (hereinafter, referred to as a 'peak image'). Detection is performed using distribution and average signal level (ASL).

3 is a diagram illustrating an example of such a peak image. In FIG. 3, hatched portions represent dark gray scales, and non-hatched portions represent bright gray scales. The signal as shown in FIG. 3 is an image in which only the middle part of the entire screen is light gray (for example, the highest gray scale) and the remainder is dark (for example, the minimum gray scale). The brightness quality is determined by measuring how much the brightness is. In addition, when the image as shown in FIG. 3 is turned on for a long time and is converted into another image, an image sticking phenomenon occurs. Meanwhile, in FIG. 3, the peak image shows an image in which only the middle part is a bright gray level, but this is an example, and only a portion other than the middle part is light gray and the other part is a dark gray level. The present invention described below can be applied to determine that.

FIG. 4A illustrates a histogram distribution of a peak image, and FIG. 4B illustrates a distribution of a histogram of a general image. The histogram distribution is a graph showing the distribution of gray levels in a video signal of one frame. In FIG. 4A and FIG. 4B, the histogram distribution is shown only when the total gray levels are divided into 32 steps (HIS_0, HIS_1, .... HIS_29, HIS_30, HIS_31). It can be divided into many steps or fewer steps. In the case of the peak image as shown in FIG. 3, since most of the low gradation, some of the high gradation exist in the middle portion, and little data of the remaining middle gradation exist, it has a histogram distribution as shown in FIG. 4A. . However, the general image has a histogram distribution as shown in FIG. 4B because it is evenly distributed in various gray levels.

Meanwhile, since the peak image as shown in FIG. 3 is a signal having a small average signal level and lower than a predetermined reference value, the peak image detector 220 detects the average signal level. Here, the predetermined reference value is a preset value and can be obtained through an experimental method by jumping the image of FIG. 3 as a test image. The average signal level ASL for each frame is calculated by Equation 1 below.

In Equation 1, R _{x , y} , G _{x , y} , B _{x , y} are R, G, B gray scale values in discharge cells at (x, y) positions, respectively, and N and M are horizontal and vertical frames, respectively. Is the size.

Therefore, the peak image detector 220 inputs when the histogram distribution is distributed only in low and high gray levels as shown in FIG. 4A and the average signal level ASL calculated using Equation 1 is lower than a predetermined reference value. The video signal is determined as a peak image. The peak image detector 220 transmits whether the input image signal is a peak image to the peak image processor 260. In addition, the peak image detector 220 transmits the average signal level ASL calculated using the equation 1 and whether the image is a peak image to the automatic power controller 240.

If the peak power is not a peak image, the automatic power controller 240 adjusts the automatic power control level according to the average signal level ASL received from the peak image detector 220. The total sustain discharge pulse number corresponding to the detected APC level is determined using a look-up table as shown in FIG. 5. The automatic power controller 240 transmits the determined total number of sustain discharge pulses to the scan and sustain electrode driving controller 280. Here, the APC level is preset to a plurality of levels according to the ASL, and in FIG. 5, the APC level applied by the automatic power control unit 240 is represented by 0 to 255. This is just one example and may be changed to another level. Of course it can.

5 is a look-up table showing the total number of sustain discharge pulses corresponding to the APC level. In FIG. 5, the peak image level among the APC levels is a level applied by the peak image processor 260 described below, and 0 to 255 are levels applied by the automatic power controller 240. In FIG. 5, the total number of sustain discharge pulses is denoted by symbols (Sus_peak, Sus_apc0, Sus_apc1, Sus_apc2, Sus_apc253, Sus_apc254, Sus_apc255), but are actually set to numbers. Here, in the case of the peak image, the maximum number of sustain discharge pulses is set in Sus_peak for the highest luminance, and the total number of sustain discharge pulses as the APC level is higher to set the power consumption below a certain level. Set to reduce the value of. That is, in FIG. 5, a smaller number of total sustain discharge pulses is set from Sus_peak to Sus_apc255.

The peak image processor 260 receives whether it is a peak image from the peak image detector 220 and, in the case of the peak image, determines the total sustain discharge pulse number Sus_peak corresponding to the peak image level with reference to the lookup table of FIG. 5. do. Here, Sus_peak, which is the total number of sustain discharge pulses corresponding to the peak image level, corresponds to the largest number of sustain discharge pulses, and thus the brightest image is displayed in the case of the peak image. In general, the plasma display device displays a peak image as shown in FIG. 5 to check the luminance of the plasma display device to determine the grade. In the exemplary embodiment of the present invention, a high luminance quality is obtained by allocating the largest number of sustain discharge pulses. You can get it.

On the other hand, the peak image processing unit 260 is a total sustain discharge pulse corresponding to the peak image level when continuously input for a predetermined time of the peak image in order to prevent the image sticking phenomenon occurs in the peak image Change the number. That is, the peak image processor 260 drops the total number of sustain discharge pulses to Sus_apc0 or Sus_apc1 and the like other than Sus_peak when the peak image is continuously input for a predetermined time. As such, when the peak image persists for a predetermined time, image sticking may be prevented by reducing the total number of sustain discharge pulses allocated to the peak image. Here, the predetermined time is a time at which image sticking occurs when the peak image is continuously input, and can be obtained through an experimental method.

Then, the peak image processing unit 260 transmits the information about the total number of sustain discharge pulses determined for the peak image to the scan and sustain drive control unit 280.

The scan and sustain electrode driving controller 280 is configured to apply the total sustain discharge pulses transmitted from the automatic power controller 240 or the peak image processor 260 to the scan electrodes Y1 to Yn and the sustain electrodes X1 to Xn. The control signal is generated and transmitted to the scan electrode driver 400 and the sustain electrode driver 500.

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.

As described above, according to the present invention, the peak image is detected, and in the case of the peak image, the maximum total number of sustain discharge pulses is increased to improve luminance, and the total number of sustain discharge pulses is reduced when the peak image is sustained for a predetermined time. This can prevent afterimage phenomenon.

Claims (11)

A driving method of a plasma display device which drives a video signal of one frame input into a plurality of subfields. Detecting whether the image signal of the one frame is a peak image having a predetermined region having a first gray scale and the remaining region having a second gray scale lower than the first gray scale; When the image signal of the one frame is a peak image, assigning the first total sustain discharge pulse number to the peak image than the non-peak image and applying the same to the peak image; And If the peak image signal lasts for a predetermined time, assigning the second total sustain discharge pulse number less than the first total sustain discharge pulse number to the peak image and applying the same to the plasma display device; Method of driving the device. The method of claim 1, Detecting whether it is the peak image, Detecting a distribution of a histogram of the video signal of one frame; And And calculating a value of an average signal level of the image signal of the one frame. The method of claim 2, And determining that the peak image is distributed when the histogram is distributed only in the first gray level and the second gray level, and the value of the average signal level is smaller than a predetermined value. The method according to any one of claims 1 to 3, And the first gray level is the highest gray level among the gray levels displayed on the plasma display device, and the second gray level is the lowest gray level among the gray levels displayed on the plasma display device. The method according to any one of claims 1 to 3, And the predetermined area corresponds to a center portion of a screen of the plasma display device. The method according to any one of claims 1 to 3, And the first total sustain discharge pulse number is the largest number of the total number of sustain discharge pulses applied to one frame. A plasma display panel forming a plurality of discharge cells; A controller configured to control an image signal of one input frame to be divided into a plurality of subfields; And A driving unit driving the plasma display panel according to a control signal of the controller; The control unit, Detects whether the video signal of one frame is a peak image having a first gray level in a predetermined region and the second gray level lower than the first gray scale, and if the video signal of one frame is a peak image. The first total sustain discharge pulse number of the total sustain discharge pulses applied to the frame is allocated to the peak image and applied to the plasma display panel. When the peak image signal lasts for a predetermined time, the first total sustain pulse is applied. And a second total sustain discharge pulse number less than the discharge pulse number is assigned to the peak image to be applied to the plasma display panel. delete The method of claim 7, wherein The control unit, When the histogram distribution of the image signal of one frame is distributed only in the first gray level and the second gray level, and the value of the average signal level of the image signal of the one frame is smaller than a predetermined value, the plasma is determined as the peak image. Display device. The method according to claim 7 or 9, The first gray level is the highest gray level among the gray levels displayed on the plasma display panel, and the second gray level is the lowest gray level among the gray levels displayed on the plasma display panel. The method according to claim 7 or 9, And the predetermined area corresponds to a central portion of a screen of the plasma display panel.

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