KR20080009476A - Plasma display panel device and driving method thereof - Google Patents

Abstract

A plasma display device and a driving method thereof are provided to correct the number of sustain discharge pulses of each subfield by the number of sustain discharge pulses in correspondence with a brightness reduction ratio corresponding to a load of each subfield. The number of a first sustain discharge pulses to be applied to each subfield is calculated by using a first image signal(S702), and then a load of each subfield is calculated by using the first image signal(S703). A brightness reduction ratio is calculated by using brightness information corresponding to the load of each subfield(S704). The number of the first sustain discharge pulses of each subfield is recalculated in correspondence with the reduction ratio of each subfield(S705). A driving signal corresponding to the number of the second sustain discharge pulses is output(S706).

Description

Plasma display device and driving method thereof

1 is an example histogram showing a load for each subfield.

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

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

4 is a graph showing the relationship between the number of sustain discharge pulses and the luminance according to the load.

5 is a graph showing the relationship between the number of sustain discharge pulses and the average efficiency according to the load.

FIG. 6 is an exemplary diagram in which luminance values and average luminance values for respective loads are recorded according to the number of sustain discharge pulses.

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

8 is a table showing the number of sustain discharge pulses of each subfield calculated by the driving method according to the embodiment of the present invention.

The present invention relates to a plasma display device including a plasma display panel (PDP) and a driving method thereof.

A plasma display device is a flat display device that displays characters or images using plasma generated by gas discharge, and has a plasma display panel in which several tens to millions or more of pixels are arranged in a matrix form according to its size.

In general, a plasma display device divides one frame into a plurality of subfields having respective weights, and displays grayscales by combining each subfield. Each subfield has a reset period, an address period, and a sustain period based on time. The reset period initializes the state of each cell to smoothly perform an address operation on the cell. The address period selects a cell to be turned on from the plurality of cells through the address discharge, and in the sustain period, a sustain discharge pulse having a high level voltage and a low level voltage alternately applied to the scan electrode and the sustain electrode in the opposite phase and held in the cell to be turned on. Discharge occurs. At this time, the number of sustain discharge pulses applied during the sustain period is proportional to the weight of the corresponding subfield.

In such a plasma display device, the main factor for determining the luminance is the number of sustain discharge pulses used during one frame. The plasma display uses about 1500 to 4000 sustain discharge pulses in one frame to obtain a peak luminance of 1000 to 1500 cd / m 2.

However, even when the same number of sustain discharge pulses is applied to the plasma display device, the luminance represented by the area on which the screen is turned on is changed, and the luminance may cause distortion of the image.

For example, as illustrated in FIG. 1, when an image signal having a load ratio of the 11th subfield among the 11 subfields is lower than that of other subfields, a gray level using the 11th subfield is displayed. Breaking phenomenon occurs. This is because, when the load of the subfield is large, the luminance is greatly reduced, and when the load is small, the luminance is hardly reduced and the luminance difference for each subfield is increased.

SUMMARY OF THE INVENTION The present invention has been made in an effort to solve a conventional problem, and to provide a plasma display device and a driving method thereof for preventing distortion of an image expression.

According to an aspect of the present invention for achieving the above object, in the driving method of the plasma display device for driving the first video signal of the input frame is divided into a plurality of sub-fields, Calculating a number of first sustain discharge pulses applied to the subfield; Calculating a load of each subfield by using the first video signal; Determining a luminance reduction ratio using luminance information corresponding to the load of each subfield; Recalculating the number of first sustain discharge pulses of each subfield as the number of second sustain discharge pulses, corresponding to the brightness reduction ratio of each subfield; And outputting a driving signal corresponding to the second sustain discharge pulse number.

According to another aspect of the present invention for achieving the above object, a plasma display panel for forming a plurality of discharge cells; A controller configured to control an input one frame first image signal 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 calculates the number of first sustain discharge pulses of each subfield and the load of each subfield by using the first video signal, determines a luminance reduction ratio corresponding to the load of each subfield, Corresponding to the luminance reduction ratio of the subfield, the number of first sustain discharge pulses of the respective subfields is recalculated as the number of second sustain discharge pulses.

 According to another aspect of the invention, the control unit, the sustain pulse number calculation unit for calculating the total number of sustain discharge pulses corresponding to the load ratio of the first video signal and the number of first sustain discharge pulses for each subfield, the first A subfield data converter for converting a video signal into subfield data and outputting the address electrode driving signal to the driver; a subfield load calculator for calculating a load of each subfield with the subfield data; and a load of each subfield The memory storing the brightness reduction ratio information for each star, the brightness reduction ratio corresponding to the load of the subfield is determined, and the number of first sustain discharge pulses of each subfield is determined by the second sustain discharge pulse number corresponding to the brightness reduction ratio. Generate a sustain pulse inverse calculating section for recalculating a second pulse; and an electrode drive signal corresponding to the number of second sustain discharge pulses in each subfield received from the sustain pulse inverse calculating section. And an X / Y control unit output to the driving unit.

The second sustain discharge pulse number is obtained by dividing the first sustain discharge pulse number by the luminance reduction ratio.

The luminance reduction ratio is a luminance ratio for each of the number of sustain discharge pulses in which the luminance represented on the screen corresponding to a specific load is converted into a ratio of the maximum luminance, or an average of the luminance ratios for each of the plurality of sustain discharge pulses.

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.

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

Prior to description, the output luminance characteristics according to the screen display area and the luminance characteristics (luminance ratio, average efficiency, reduction ratio) according to the number of sustain discharge pulses according to the screen display area will be described with reference to FIGS. It demonstrates as follows.

4 is a graph showing the relationship between the number of sustain discharge pulses and the luminance according to the load, Figure 5 is a graph showing the relationship between the number of sustain discharge pulses and the average efficiency according to the load, Figure 6 is according to the number of sustain discharge pulses An exemplary diagram recording the luminance value and the average luminance value for each load. 4 to 6, the display area of the screen is displayed as a load that is proportionally changed according to the change thereof.

In order to determine the relationship between the number of sustain discharge pulses and the output luminance according to the screen display area, the number of experimental sustain discharge pulses is fixed to 40, 70, 100, 130, and the luminance of each screen is changed while varying the display area of the screen. Was measured.

The result is the luminance data for each load according to the number of sustain discharge pulses shown in FIG. 6, which is the same as FIG. 4 and FIG. 5.

4 to 6, it can be seen that the luminance is decreased as the load (that is, the screen display area) is increased in the same number of sustain discharge pulses.

Specifically, the load-specific luminance according to the number of sustain discharge pulses 40, 70, 100 and 130 is measured by the actual luminance value shown in FIG. Referring to the actual luminance value of FIG. 6, the luminance varies depending on the number of sustain discharge pulses. In particular, the larger the number of sustain discharge pulses, the higher the displayable luminance and the higher the luminance displayed for each load.

The luminance ratio for each load is determined to determine the luminance reduction for each specific discharge pulse with respect to the number of sustain discharge pulses and the load. In this case, the luminance ratio can be obtained as actual luminance / maximum luminance) * 100 at the corresponding load. The luminance ratio for each load relative to the number of sustain discharge pulses thus obtained is described in the luminance ratio column of FIG. 6.

By the way, in the luminance ratio column of FIG. 6, it can be seen that the luminance ratio for each load according to the number of sustain discharge pulses is almost the same (the error is almost insignificant) at the same load. Therefore, since the luminance at the same load is almost the same regardless of the number of sustain discharge pulses (see FIG. 5), the average efficiency of the furnace for each sustain discharge pulse number at the same load is obtained (see the average efficiency of FIG. 6). It can be set as the luminance ratio for a specific load of all sustain discharge pulses.

If the average efficiency is obtained in this way, the luminance reduction ratio can be easily obtained by considering only the load. The luminance reduction ratio is a degree indicating how much the luminance at the load is reduced at the maximum luminance, which corresponds to the average efficiency at the load.

Referring to the average efficiency column of FIG. 6, for example, when the number of sustain discharge pulses is 130 and the load is 15, the luminance reduction ratio is 77, which is the average efficiency, and the degree of reduction is 23. (The luminance reduction ratio calculated using the average efficiency is almost the same as the luminance reduction ratio calculated using the luminance ratio or the actual luminance.)

As a result, the luminance difference between the subfields due to the area difference of the screen is turned on to compensate for the reduction of the luminance according to the load, thereby reducing the luminance error between the subfields, thereby preventing the gradation distortion.

Therefore, the embodiment of the present invention compensates the number of sustain discharge pulses as much as the brightness reduction ratio in order to compensate for the brightness reduction according to the load and re-determines the number of sustain discharge pulses of the corresponding subfield.

A plasma display device according to an embodiment of the present invention will now be described with reference to FIG. 2. 2 is a schematic diagram of a plasma display device according to an exemplary embodiment of the present invention. As illustrated in FIG. 2, the plasma display apparatus includes a plasma display panel 100, a controller 200, an address driver 300, a scan electrode driver 400, and a sustain electrode driver 500.

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 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 controller 200 receives an image signal from the outside and outputs an address driving control signal, a sustain electrode driving control signal, and a scan electrode driving control signal. To this end, the controller 200 displays an image by dividing one frame into a plurality of subfields having a weight. In this case, the controller 200 adjusts the number of sustain discharge pulses of each subfield by using the load of each subfield and the luminance reduction ratio according to the load to prevent gradation distortion due to the difference in the area (that is, the load) on which the screen is turned on. .

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

The sustain electrode driver 500 receives the sustain electrode driving control signal from the controller 200 and applies a driving voltage to the sustain electrode. The scan electrode driver 400 receives a scan electrode driving control signal from the controller 200 and applies a driving voltage to the scan electrode.

Here, the operation of the controller 200 shown in FIG. 2 will be described in more detail with reference to FIG. 3. 3 is a block diagram of a control unit according to an embodiment of the present invention.

As shown in FIG. 3, the control unit 200 includes a gamma correction unit 210, a sustain pulse number calculator 220, a subfield data converter 230, a subfield load calculator 240, and a sustain pulse number. The inverse calculator 250, the memory 260, and the X / Y controller 270 are included.

The gamma correction unit 210 receives an image signal and performs gamma correction to output the image signal to the sustain pulse number calculation unit 220 and the subfield data conversion unit 230.

The sustain pulse calculator 220 calculates an average signal level (ASL) for each frame from the input image signals R, G, and B data, and automatically controls power according to the calculated average signal level. Detect power control level. The APC level is preset to a plurality of levels (0 to 255) in accordance with the ASL.

In general, detecting whether the input image signal data is data that consumes a lot of power is called detection of a load ratio. In an embodiment of the present invention, detection of a load ratio is determined based on an average signal level ASL. It is shown that it is, but other well-known methods are also possible. For example, a method of determining through subfield data may be used.

The sustain pulse number calculation unit 220 stores a lookup table in which total sustain discharge pulse number information applied to one frame for each APC level is recorded, and the total sustain discharge pulse number corresponding to the APC level using the lookup table. The number of sustain discharge pulses for each subfield is determined.

The subfield data converter 230 converts an image signal provided by the gamma correction unit 210 into subfield data and outputs the address signal to the address electrode driver 300 as an address electrode driving signal.

The subfield load calculator 240 calculates the load of each subfield by using the subfield data converted by the subfield data converter 230.

The sustain pulse reverse calculation unit 250 receives the sustain discharge pulse number information (the number of sustain discharge pulses per subfield or / and the total number of sustain discharge pulses) from the sustain pulse number calculation unit 220, and the subfield load calculator 240 Load of each subfield, and the number of sustain discharge pulses for each subfield whose luminance reduction is compensated using the received information and luminance information (luminance ratio and average efficiency) for each subfield load previously stored 1) and calculates it to the X / Y control unit 270.

The memory 260 stores luminance information for each load as shown in FIG. 6. In some cases, the memory 260 may store only average efficiency information for each load.

The X / Y controller 270 generates a sustain electrode driving signal corresponding to the number of first luminance compensation sustain discharge pulses received from the sustain pulse inverse calculator 250, and provides the sustain electrode driving signal to the sustain electrode driver 500. The scan electrode driving signal corresponding to the number of compensation sustain discharge pulses is generated and provided to the scan electrode driver 400.

Herein, a driving method of the plasma display device according to an exemplary embodiment of the present invention will be described with reference to FIGS. 7 and 8. 7 is a flowchart illustrating a method of driving a plasma display device according to an exemplary embodiment of the present invention, and FIG. 8 is a table illustrating the number of sustain discharge pulses of each subfield calculated by the driving method according to an exemplary embodiment of the present invention.

As shown in FIG. 7, when an external image signal is received by the plasma display device (S701), the gamma correction unit 210 performs gamma correction to the sustain pulse number calculation unit 220 and the subfield data conversion unit 230. Is provided.

The sustain pulse number calculation unit 220 calculates the load ratio for the video signal and grasps the sustain discharge pulse number Pt1 of each subfield reflecting the total number of sustain discharge pulses and each weight through the stored lookup table using the load ratio. The sustain discharge pulse number Pt1 of each subfield is provided to the sustain pulse inverse calculation unit 250 (S702).

The subfield data converter 230 converts an image signal provided by the gamma correction unit 210 into subfield data, outputs the address signal as an address electrode driving signal, and provides the subfield data to the subfield load calculator 240. . The subfield load calculation unit 240 calculates the load of each subfield by using the received subfield data (R, G, B data), and maintains the load information of each subfield. (S703).

The sustain pulse inverse calculation unit 250 receives the sustain discharge pulse number Pt1 of each subfield to the sustain pulse number calculation unit 220 and receives load information of each subfield from the subfield load calculation unit 240. In operation S704, the average efficiency Pa of each subfield is determined through the memory 260.

Then, the sustain pulse inverse calculator 250 matches the average efficiency Pa and the number of sustain discharge pulses Pt1 of each subfield for the same subfield and substitutes the following Equation 1 to calculate luminance of each subfield. The sustain discharge pulse number Pt2 is calculated again (S705).

Pt2 = Pt1 / Pa

In Equation 1, the number of sustain discharge pulses Pt1 of the corresponding subfield is calculated in a state where the luminance is reduced by (100% -Pa%) by the load. Therefore, multiplying 1 / Pa by the fat-dielectric pulse number Pt1 compensates for the number of sustain discharge pulses Pt2 that can represent 100%.

For example, when the total number of sustain discharge pulses calculated by the sustain pulse number calculation unit 220 is 513, and the load of each subfield is as shown in FIG. 8A, the sustain discharge first calculated for the 11th subfield is shown. The number of pulses Pt1 is 148 which is 513 * (296/1024), and the number of sustain discharge pulses Pt2 which have been compensated for luminance is compensated by the average efficiency of 0.76 to 172 which is {513 * (296/1024)} / 0.76.

The sustain pulse inverse calculation unit 250 provides the X / Y control unit 270 with the number of sustain discharge pulses Pt2 of each subfield recalculated by Equation (1). Then, the X / Y control unit 270 generates a sustain / scan driving signal corresponding to the received sustain discharge pulse number Pt2 and provides it to the scan electrodes and the sustain electrode driving units 400 and 500 (S706).

On the other hand, in the above-described embodiment of the present invention, although the average efficiency is used to re-determine the number of sustain discharge pulses compensated for luminance reduction, the luminance ratio may be used instead of the average efficiency. In the case of using the average efficiency, only the load may be considered. In the case of using the luminance ratio, the total number of sustain discharge pulses and the load may be considered.

Through the above description, the embodiment of the present invention compensates Pt1 of each subfield with Pt2 capable of 100% luminance, and prevents the luminance difference between each subfield from increasing due to the difference in the displayed area of the screen. Prevents distortion.

The embodiments of the present invention described above are not implemented only through the apparatus and the method, but may be implemented through a program for realizing a function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded. Implementation can be easily implemented by those skilled in the art from the description of the embodiments described above.

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 distortion of the image expression is prevented by compensating for the luminance difference between the subfields depending on the area where the screen is turned on.

Claims (9)

A driving method of a plasma display device which drives a first video signal of one input frame divided into a plurality of subfields. Calculating a number of first sustain discharge pulses applied to each subfield using the first video signal; Calculating a load of each subfield by using the first video signal; Determining a luminance reduction ratio using luminance information corresponding to the load of each subfield; Recalculating the number of first sustain discharge pulses of each subfield as the number of second sustain discharge pulses, corresponding to the brightness reduction ratio of each subfield; And And outputting a driving signal corresponding to the second sustain discharge pulse number. The method of claim 1, The relationship between the first sustain discharge pulse number and the second sustain discharge pulse number is expressed by the following equation. Pt2 = Pt1 / Pa Pt2: Recalculated second sustain discharge pulse number, Pt1: Number of first sustain discharge pulses, Pa: Luminance reduction ratio. The method according to claim 1 or 2, And the luminance reduction ratio is an average of luminance ratios of a plurality of sustain discharge pulses in which luminance represented on a screen corresponding to a specific load is converted into a ratio of maximum luminance. The method according to claim 1 or 2, And the luminance reduction ratio is a luminance ratio obtained by converting the luminance represented on the screen corresponding to a specific load from the number of sustain discharge pulses into a ratio with the maximum luminance. A plasma display panel forming a plurality of discharge cells; A controller configured to control an input one frame first image signal 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, The first sustain discharge pulse number of each subfield and the load of each subfield are calculated using the first video signal, the luminance reduction ratio corresponding to the load of each subfield is determined, and the luminance of each subfield is obtained. And a second oil discharge pulse number of each of the subfields is recalculated as a second sustain discharge pulse number in response to the reduction ratio. The method of claim 5, The control unit, A sustain pulse number calculation unit for calculating a total number of sustain discharge pulses corresponding to the load ratio of the first video signal and a number of first sustain discharge pulses for each subfield;  A subfield data converter converting the first image signal into subfield data and outputting the address electrode driving signal to the driver; A subfield load calculation unit calculating a load of each subfield using the subfield data; A memory that stores luminance reduction ratio information for each subfield in each load; A sustain pulse inverse calculating section which grasps the brightness reduction ratio corresponding to the load of the subfield and recalculates the first sustain discharge pulse number of each subfield as the second sustain discharge pulse number in response to the brightness reduction ratio; , And an X / Y control unit for generating an electrode driving signal corresponding to the number of second sustain discharge pulses of each subfield received from the sustain pulse inverse calculating unit and outputting the electrode driving signal to the driving unit. The method according to claim 5 or 6, The relationship between the first sustain discharge pulse number and the second sustain discharge pulse number is expressed by the following equation. Pt2 = Pt1 / Pa Pt2: Recalculated second sustain discharge pulse number, Pt1: Number of first sustain discharge pulses, Pa: Luminance reduction ratio. The method of claim 7, wherein And the luminance reduction ratio is an average of luminance ratios of a plurality of sustain discharge pulses in which luminance represented on a screen corresponding to a specific load is converted into a ratio of maximum luminance. The method of claim 7, wherein And the luminance reduction ratio is a luminance ratio obtained by converting the luminance expressed on the screen corresponding to a specific load from the number of sustain discharge pulses into a ratio with the maximum luminance.

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