KR100796684B1 - Plasma display and driving method thereof - Google Patents

Abstract

The plasma display device calculates a load ratio of each subfield from a plurality of image data corresponding to one frame, converts the plurality of image data into a plurality of subfield data, respectively, and outputs a control signal. The plasma display device converts the first image data of the first frame into the first subfield data according to the load ratio of at least one subfield, and the second image data having the same gray level as the first image data of the second frame. Is converted into second subfield data different from the first subfield data. In this way, the luminance deviation according to the load ratio can be reduced.

PDP, subfield, load factor, subfield generation

Description

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

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

2 illustrates a subfield arrangement according to an embodiment of the present invention.

3 is a schematic block diagram of a control unit according to an embodiment of the present invention.

4A and 4B are diagrams illustrating generation of subfield data in the second and first subfield generators of the controller of FIG. 3, respectively.

5 is a flowchart illustrating a method of generating subfield data in a control unit according to an embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display device and a driving method thereof, and more particularly to a method for allocating sustain discharge pulses.

The plasma display device is a device that displays characters or images using plasma generated by gas discharge. In general, a plasma display device is driven by dividing a frame into a plurality of subfields having respective luminance 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 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 the display panel of the plasma display device, a plurality of row electrodes and a plurality of column electrodes are formed, and discharge cells are formed at points where the row electrodes and the column electrodes intersect. Accordingly, the magnitude of the current flowing through the plurality of row electrodes varies according to the number of light emitting cells in each subfield, and thus the magnitude of the voltage drop also varies. Then, the smaller the number of light emitting cells, the smaller the magnitude of the voltage drop, and the higher the luminance in one discharge cell. That is, the luminance represented by one subfield may vary depending on the number of light emitting cells, so that the total gray scale represented by the combination of a plurality of subfields may vary. However, when the number of light emitting cells is large, the luminance change is not large due to the saturation characteristic even when the number of light emitting cells is different, but when the number of light emitting cells is small, the luminance change according to the number of light emitting cells may be large.

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 compensating a luminance varying depending on the number of light emitting cells in a subfield.

In order to solve this problem, according to one embodiment of the present invention, a plasma display device including a plurality of discharge cells, a control unit and a driving unit is provided. The control unit divides one frame into a plurality of subfields having respective weights, calculates a load ratio of each subfield from the plurality of video data corresponding to one frame, and converts the plurality of video data into a plurality of subfield data, respectively. It converts and outputs a control signal. The driver drives the plurality of discharge cells in accordance with a control signal from the controller. In this case, the controller converts the first image data of the first frame into the first subfield data according to the load ratio in the at least one subfield, and the second image data having the same gray level as the first image data of the second frame. Is converted into second subfield data different from the first subfield data.

In this case, the control unit may include a load ratio determination unit that determines a load ratio of each subfield from the plurality of image data, and a subfield generation determination unit that detects image data using a subfield in which the load ratio satisfies a predetermined condition among the plurality of image data. A first subfield generator for converting the detected image data into subfield data in a first manner, and converting at least one image data other than the detected image data among the plurality of image data into subfield data in a second manner It may include a second subfield generating unit.

According to another embodiment of the present invention, there is provided a driving method of a plasma display device which divides and drives one frame into a plurality of subfields having respective weights. The driving method includes calculating a load factor in each subfield from a plurality of image data input during one frame, determining a subfield having a first load rate range,

Converting at least one first image data using a subfield having a first load ratio range into subfield data in a first manner, and at least one of image data other than the first image data among the plurality of image data And converting the second image data into the subfield data in a second method different from the first method.

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.

A plasma display device and a driving method thereof according to an exemplary embodiment of the present invention will now be described in detail with reference to the accompanying drawings.

1 is a schematic conceptual diagram of a plasma display device according to an exemplary embodiment of the present invention, and FIG. 2 is a diagram illustrating an arrangement of subfields 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 sustain electrode driver 400, and a scan electrode driver 500. ).

The plasma display panel 100 includes a plurality of address electrodes (hereinafter referred to as "A electrodes") A1-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-Xn) and scan electrodes (hereinafter referred to as" Y electrodes ") (Y1-Yn). In general, the X electrodes X1 to Xn are formed corresponding to the respective Y electrodes Y1 to Yn, and the row electrodes are formed by the adjacent X and Y electrodes. The Y electrodes Y1-Yn and the X electrodes X1-Xn are arranged to be orthogonal to the A electrodes A1-Am, and the A electrodes A1-Am and the X and Y electrodes X1-Xn and Y1-. The discharge space at the intersection of Yn) forms the discharge cell 110.

As illustrated in FIG. 2, the controller 200 divides one frame into a plurality of subfields SF1-SF11 having respective luminance weights, and each subfield includes an address period and a sustain period. The controller 200 calculates a load ratio of each subfield from a plurality of image data corresponding to one frame. The controller 200 converts image data using a subfield having a load ratio lower than a threshold value among the plurality of image data into subfield data in a second manner, and converts remaining image data into subfield data in a first manner. . At this time, the subfield data is converted into data indicating whether light emission / non-emission is performed in the plurality of subfields SF1-SF11.

In this case, in FIG. 2, one frame is composed of eleven subfields SF1-SF11 having weights of 1, 2, 3, 5, 8, 13, 20, 32, 45, 57, and 69, respectively. It can be expressed as possible. For example, the controller 200 may selectively convert 120 grayscale input data into subfield data of “11001011010” or subfield data of “01110111100”. Here, "11001011010" and "01110111100" correspond to the plurality of subfields SF1-SF11 in order, '1' indicates that the discharge cells emit light in the corresponding subfield, and '0' indicates discharge cells in the corresponding subfield. This does not emit light.

The controller 200 rearranges the subfield data with respect to each subfield to generate a control signal for driving the drivers 300, 400, and 500 in each subfield. 500). The address, sustain, and scan electrode drivers 300, 400, and 500 respectively control the A electrodes A1-Am, the X electrodes X1-Xn, and the Y electrodes Y1-Yn according to control signals from the controller 200. Drive.

Hereinafter, a method of generating subfield data according to a load ratio for each subfield by the controller 200 will be described in detail with reference to FIGS. 3 to 5.

3 is a schematic block diagram of a controller 200 according to an embodiment of the present invention, and FIGS. 4A and 4B respectively illustrate subfield data generation in the second and first subfield generators of the controller of FIG. 3. 5 is a flowchart illustrating a method of generating subfield data in the controller 200 according to an exemplary embodiment of the present invention. 4A and 4B show only subfield data of 1 to 32 gray scales among 0-255 gray scales for convenience.

As shown in FIG. 3, the control unit 200 according to an embodiment of the present invention may include a load factor calculator 210, a subfield generation determiner 220, a first subfield generator 231, and a second subfield. The generator 232 and the subfield rearrangement unit 240 are included.

The load factor calculator 210 calculates a load factor for each subfield from image data corresponding to one frame, and the subfield generation determiner 220 determines a subfield having a load factor lower than a threshold. The subfield generation determining unit 220 transfers the image data using the subfield having a load ratio lower than the threshold value among the image data of one frame to the first subfield generating unit 231 and transmits the remaining image data to the second subfield. Transfer to subfield generation unit 232. The first subfield generation unit 231 converts the received image data into subfield data in a first manner and outputs the subfield data. The second subfield generation unit 232 outputs the received image data different from the first scheme. Converted to subfield data in two ways and outputted. The subfield rearranging unit 240 rearranges the subfield data from the first and second subfield generating units 231 and 232 into subfields, and then controls the driving signals 300, 400, and 500 to drive the driving units 300, 400, and 500. Create and print

For example, the second subfield generator 231 converts the image data into subfield data as shown in FIG. 4A, and the first subfield generator 231 converts the image data into subfield data as shown in FIG. 4B. can do. In this way, image data having the same gradation can be converted to other subfield data according to the subfield load ratio. In this case, the first and second subfield generators 231 and 232 may store the subfield data corresponding to the image data in the form of a lookup table as shown in FIGS. 4B and 4A, respectively.

Specifically, the load factor calculator 210 converts the image data into subfield data using, for example, the second method of the second subfield generator 232, and discharges a plurality of discharges in each subfield from the subfield data. The load factor of each subfield is calculated by measuring the number of light emitting cells in the cell (S510). That is, the load ratio of each subfield is given by the ratio of the total number of discharge cells and the number of light emitting cells in the subfield.

The subfield generation determining unit 220 determines a subfield having a load ratio lower than a threshold value from the measured subfield load ratio (S520), and emits a light from a subfield having a load ratio lower than a threshold value among image data of one frame. Data is detected (S530). At this time, the subfield with a load factor of 0 is excluded because there are almost no light emitting cells. The subfield generation determination unit 220 transfers the first image data to the first subfield generation unit 231 and the remaining second image data to the second subfield generation unit 232 (S540). Then, the first subfield generator 231 converts the first image data into subfield data in a first manner (for example, FIG. 4B), and the second subfield generator 232 converts the second image data. The subfield data is converted into subfield data using the second method (for example, the method of FIG. 4A) (S550).

For example, when image data of 19 gradations, 20 gradations, and 21 gradations occupies (1/3) each region in one frame, the subfield data converted by FIG. 4A is "11111000000", "01010100000", "11010100000". At this time, the load rates of the subfields SF1, SF2, SF3, SF4, SF5, SF6 are 67%, 100%, 33%, 100%, 33%, and 67%, respectively. Then, the luminance characteristic in the subfield with the 33% load factor may be different from the luminance characteristic in the subfield with the different load factor.

Accordingly, the subfield generation determining unit 220 determines the subfields SF3 and SF5 having a load ratio lower than a threshold value (for example, 40%), and determines the image data using the corresponding subfields SF3 and SF5. do. That is, the 19th gradation video data uses the corresponding subfields SF3 and SF5. Then, the subfield generation determination unit 220 transfers the 19th gradation image data to the second subfield generation unit 232, and the second subfield generation unit 232 transmits the 19th gradation image data as shown in FIG. 4B. 10010100000 ". In this way, the load rates of the subfields SF1, SF2, SF3, SF4, SF5, SF6 are 67%, 67%, 0%, 100%, 0%, and 100%, respectively. Therefore, the subfield whose load factor (except 0%) is lower than the threshold value disappears.

As described above, according to the exemplary embodiment of the present invention, since the image data which makes the subfield load ratio lower than the threshold value can be converted into other subfield data, the subfield in which the luminance characteristic difference occurs because the load ratio is lower than other subfields can be eliminated. Can be.

In the exemplary embodiment of the present invention, image data corresponding to a subfield lower than a threshold is converted into other subfield data. However, in the subfield having a low load factor, since there are practically fewer light emitting cells, there is little influence on the luminance deviation, so that image data corresponding to a subfield falling between two threshold values (first and second threshold values) is different from other subfields. You can also convert it to data.

In addition, although an embodiment of the present invention uses two types of subfield data generation methods, three or more subfield data generation methods may be used.

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 exemplary embodiment of the present invention, the luminance deviation may be reduced by generating the subfield data differently according to the load ratio of the subfield.

Claims (10)

In the driving method of a plasma display device for dividing and driving one frame into a plurality of subfields having respective weights, Calculating a load ratio in each subfield from a plurality of image data input for one frame, Determining a subfield having a first load ratio range, Converting at least one first image data using the subfield having the first load ratio range into subfield data in a first manner, and Converting at least one second image data of the image data excluding the first image data among the plurality of image data into subfield data in a second manner different from the first scheme Driving method comprising a. The method of claim 1, And wherein the first load factor range includes a load factor between a first threshold value and a second threshold value. The method of claim 2, And the first threshold is zero. The method according to any one of claims 1 to 3, The subfield data converted by the first method and the subfield data converted by the second method are different for image data having at least one of a plurality of grayscales. The method according to any one of claims 1 to 3, The step of calculating the load factor, Converting the plurality of image data into a plurality of subfield data in the second manner, respectively; and Calculating a load ratio of each subfield from the plurality of subfield data by the number of cells emitting light in each subfield; Driving method comprising a. A plurality of discharge cells, A frame is divided into a plurality of subfields having respective weights, a load ratio of each subfield is calculated from the plurality of image data corresponding to the one frame, and the plurality of image data are respectively converted into a plurality of subfield data. A control unit for outputting a control signal, and A driving unit for driving the plurality of discharge cells in accordance with the control signal from the controller; Including; The control unit converts the first image data of the first frame into first subfield data according to the load ratio in at least one subfield, and the second image data having the same gray level as the first image data of the second frame. Converting into second subfield data different from the first subfield data. The method of claim 6, The control unit, A load ratio determination unit that determines a load ratio in each subfield from the plurality of image data; A subfield generation determination unit for detecting image data using a subfield having the load ratio between a first threshold value and a second threshold value among the plurality of image data; A first subfield generator for converting the detected image data into subfield data in a first manner, and A second subfield generator for converting at least one image data other than the detected image data among the plurality of image data into subfield data in a second manner; Plasma display device comprising a. The method of claim 7, wherein The first subfield data is generated when image data having the same gray level as the first image data is converted to the first method. And the second subfield data is generated when image data having the same gray level as the first image data is converted in the second manner. delete The method of claim 7, wherein And the first threshold is zero.

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