KR20080069011A - Apparatus for load effect prevention and method thereof - Google Patents

Abstract

An apparatus and a method for preventing a load effect are provided to enhance reliability by using an average value of loads on respective sub-fields comprising a previous frame as a reference value that prevents the load effect of a current frame. An apparatus for preventing a load effect includes a gray scale unit(10) and a compensation unit(20). The gray scale unit represents gradation of a frame using plural sub-fields in a still screen. The compensation unit obtains an average value of loads on respective sub-fields of a previous field and adjusts a gray scale of a frame, which is represented by the gray scale unit so as to compensate for the load effect with respect to the average value. The number of sub-fields for forming the frame is 10 to 12.

Description

Apparatus for load effect prevention and method

1 is a schematic diagram conceptually illustrating a number of subfields forming one frame in a PDP.

2 is a schematic diagram showing an example of driving the frame of FIG.

3 is a graph showing the brightness according to the load and the prevention method of the load effect thereto.

4 is a graph showing a criterion used for preventing a conventional road effect.

5 is a block diagram showing an apparatus for preventing a load effect according to an embodiment of the present invention.

6 is a schematic diagram showing a previous frame and subfields used in FIG.

7 is a flowchart showing the operation sequence of FIGS. 5 and 6;

* Description of the symbols for the main parts of the drawings *

10 ... Grandfather 20 ... Ministry of Government

The present invention relates to an apparatus and method for preventing a load effect, and more particularly, to prevent a load effect generated in a display implementing a gray level of one frame using a plurality of subfields, such as a plasma display panel (PDP). An apparatus and a method thereof are provided.

Plasma Display Panels (PDPs, hereinafter referred to as 'PDPs') are flat panel displays using gas discharge (plasma) phenomenon.

PDPs, unlike liquid crystal displays (LCDs), are difficult to directly implement gradation.

For this reason, the PDP is driven by dividing one frame into a plurality of subfields.

That is, as shown in FIG. 1, one frame is formed of several (multiple) subfields, and the operation as shown in FIG. 2 is performed internally. An example in which one frame consists of eight subfields is shown, and it can be seen that the eight subfields affect the frames in order by time.

Each of the subfields requires an operation section of an address section and a sustain section. The address section determines which cell on the screen emits light. In the sustain section, the subfield is defined in the address section. The brightness of the cell is controlled by the emission sustain time.

In the PDP, the light emission holding time is numerically used, and this corresponds to the number of sustains. Here, as the number of sustains, that is, the number of sustains, the light emission sustaining time increases.

The entire screen is composed of a plurality of cells, and the ratio of cells selected to emit light among these cells is called a load. Therefore, as the number of cells selected to emit light increases, the load increases, and as the number of selected cells decreases, the load decreases. In general, the load of each subfield constituting one frame is different.

As described above, the brightness of the selected cells is determined by adjusting the number of sustains. In reality, the brightness varies depending on the load even if the number of sustains is the same.

This is called a load effect because the larger the load, the more power is consumed and the brightness is reduced by the difference in power.

When the PDP is operated, when there is a desired brightness level for a specific subfield, the number of sustains corresponding to the brightness level is defined to express the brightness.

However, even though the same sustain number is defined according to the load due to the load effect, different brightness is expressed, that is, a gradation distortion phenomenon is displayed.

Since such a load effect is directly connected to a problem of deterioration in image quality, a technique of compensating for the distortion phenomenon of gradation due to a load change is used by further increasing or decreasing the number of sustains as the load increases or decreases.

Here, the problem is that the additional increase or decrease of the number of sustains to some extent, a criterion for this is necessary.

3 is a graph illustrating brightness according to a load and a method of preventing a load effect thereof.

Referring to FIG. 3, it can be seen that a specific load value L _ref which becomes the brightness reference level is set, and the brightness of other loads L ₁ , L ₂ , L ₃ , and L ₄ is increased or decreased in accordance with the brightness of the L _ref . have.

That is, the desired brightness reference level is set over all loads, and the brightness of the other loads is adjusted according to the brightness of the reference level.

Let's summarize the above.

① A plurality of subfields constituting the same frame generally have different loads.

② The load difference occurs due to the load difference in ①.

③ Set the standard to prevent the load effect and perform brightness adjustment according to the standard.

By the above process, the load effect can be prevented, and the problem is reliability of the above criteria.

For example, the PDP uses a calculated value (tabled) used for a series of images as the reference, and applies the calculated value (hereinafter referred to as a 'calculated value') as a reference to a still picture. The following problems are encountered with sea load effect compensation.

The calculated value is a value used to implement a continuous screen, and the value is changed. This is necessary for the implementation of continuous screens, and the problem is that due to such a change in value, its reliability is reduced when used as a reference in still pictures.

That is, as shown in FIG. 4, the calculated value set as a reference (dotted line) is continuously changed according to time, and according to the change of the value, a frame of a still picture that has performed load effect compensation according to the reference is configured. The brightness difference between the plurality of subfields (the brightness difference is generated by performing the load effect correction according to the changed criterion) is generated. This phenomenon appears to the user in the form of flickering, which leads to a problem of reduced reliability of the entire product.

The present invention has been created to improve the above problems, the load effect prevention device that can effectively prevent the load effect by presenting a fixed reference value for the still picture in the display in which one frame is formed of a plurality of sub-field and It is an object to provide a method.

This makes it possible to prevent flicker in the still picture and to satisfy the reliability of the entire product for the user.

Such a load effect preventing device and method is effective to be applied to the PDP, and therefore, another object of the present invention is to be applicable to the PDP.

In order to achieve the above object, the present invention provides a gradation unit for expressing gradation of one frame as a plurality of subfields in a still picture; And a correction unit for separately obtaining an average value of loads for each of the subfields of the previous frame, and adjusting a gray level of the frame represented by the gray level unit to perform a load effect correction based on the average value. Characterized in that made.

In this case, the frame is preferably composed of 10 to 12 subfields, and the gradation unit is configured for each subfield.

An address unit for selecting a cell to emit light; It is preferable to include a sustain section which determines the light emission sustain time of the cell selected in the address section by the number of sustains.

The correction unit may further include: an average value extracting unit obtaining an average value of loads for each subfield of a previous frame; It is preferable to include a sustain adjusting unit which performs load effect correction of each subfield of the current frame by adjusting the number of sustains based on the average value extracted by the average value extracting unit.

On the other hand, the above configuration can be applied to the plasma display panel (PDP).

Looking at the behavior of the above configuration,

CLAIMS What is claimed is: 1. A method of preventing a load effect generated when a still picture is displayed on a plasma display panel, the method comprising: separately obtaining an average value of loads for each of a plurality of subfields forming a previous frame; And performing a correction of the load effect on the subfield of the current frame corresponding to the still picture based on the average value by adjusting the number of sustains of the subfield, wherein the subfields include 10 to 12 subfields. It is preferable to be composed of dogs, and the number of sustains is preferably in the range of 0 to 12.

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

5 is a block diagram schematically illustrating an apparatus for preventing a load effect according to an exemplary embodiment of the present invention.

In the present embodiment, a display that uses a plurality of subfields to implement gradation of one frame, such as a PDP, is targeted.

Referring to FIG. 5, the apparatus for preventing a load effect according to the present embodiment includes a gradation unit 10 for expressing gradation of one frame in a plurality of sub fields in a still picture; And a correction unit 20 for separately calculating an average value of loads for each subfield of a previous frame and correcting a load effect for each subfield of a current frame corresponding to a still picture based on the average value. consist of.

The gradation unit 10 is an element for implementing gradation of one frame in a device such as a PDP. Although the gradation unit 10 is illustrated separately from each subfield in which the gradation is directly reflected, it is a concept including the subfield. May be used.

On the other hand, the frame is preferably composed of 10 to 12 sub-fields, and as shown in Figure 2, for each sub-field, an address unit for selecting a cell to emit light; It is preferable to include a sustain section which determines the light emission sustain time of the cell selected by the address section by the number of sustains.

For reference, gradation is a term that refers to the concentration transition stage from the highest concentration to the lightest effective concentration in an image image. I mean. If there are well-balanced pus from the high concentration to the middle tone (half tone) and low concentration, gradation is said to be abundant.

The correction unit 20 is a factor for preventing a load effect, and separately derives an average value L _{ref of} loads for each subfield of a previous frame and serves as a reference for a load effect prevention operation. This use of the load value of the previous frame is because the change between two adjacent frames between successive frames is not large, and the average value itself requires the entire calculation target data.

Assuming that the average value is obtained from the current frame and reflects it, the current frame is already displayed. Therefore, if the average value is obtained from this state and the brightness correction is performed to prevent the load effect, the brightness is newly adjusted. Therefore, a change in brightness may occur, which may cause discomfort to the user. Therefore, the average value of the loads for each subfield of the previous frame is used as a reference, and since there is substantially no difference between the previous frame and the current frame, it is not unreasonable to set the reference value of the current frame using the previous frame.

In the present exemplary embodiment, the previous frame is described as the immediately preceding frame. However, since the previous frame may be used in a situation in which about 60 frames per second are used, the previous frame may be used. have.

In FIG. 6, the load values of the respective subfields forming the previous frame are shown. When the current frame is a still picture, the load value of each subfield of FIG. 6 is used as a reference for the load effect correction.

The average value L _ref of the subfield load of the previous frame is an example,

L _ref = (L ₁ + L ₂ + L ₃ +… + L _n ) / n

n: number of subfields

L _n : Load of subfields

Can be obtained.

The point of this embodiment is to provide a separate reference for preventing the load effect of the still picture, and the reference is set so that it is fixed without being changed, so that the load L ₁ , L of the subfield of the previous frame is fixed. ₂ , L ₃ ,.. One load may be selected from L _n and used instead of the average value.

However, the load L ₁ , L ₂ , L ₃ ,... Of the subfield of the previous frame. Since L _{ref, which} is an average value of L _n , will approximate an average value of the loads of the current subfield, the degree (width) of brightness adjustment performed at the time of the load effect correction is less than that of selecting another criterion. Since the heterogeneity between the current frame and the previous frame where the prevention of the load effect is performed can be reduced to provide a comfortable screen to the user, it is preferable to use the average value L _ref as a reference.

The correction unit 20 corrects the load effect for each subfield of the current frame corresponding to the still picture based on the average value L _ref obtained as described above. For example, in the PDP, the number of sustains for determining the brightness of each subfield is determined. It will be performed by increasing or decreasing. At this time, the number of sustain used preferably has a range of 0 to 12.

Looking at the correction unit 20 described above in more detail, the average value extraction unit for obtaining the average value of the load for each sub-field of the previous frame; It may be configured to include a sustain adjustment unit for performing a load effect correction of each sub-field of the current frame by adjusting the number of sustains based on the average value extracted by the average value extraction unit, the operation of the load effect prevention device of such a configuration Referring to FIG. 7, first, the loads L ₁ , L ₂ , L ₃ ,... For each of the plurality of subfields forming the previous frame. In addition, the average value L _ref of L _n is separately obtained through the average value extracting unit (S 110), and the load effect correction for the sub field of the current frame corresponding to the still picture based on the average value L _ref is performed. It is performed by the adjustment (S 120).

In the above, although the average value extracting section and the sustain adjusting section are elements of the correcting section, the sustain adjusting section may be configured in association with the gray scale section, and the configuration may be the same as the conventional one or may be changed. That is, since the sustain part of the gradation part and the sustain adjustment part of the correction part have the same function, the two elements can be combined and used as one. In this case, the correction unit separately obtains an average value of loads for each of the subfields of the previous frame, and adjusts the gray level of the frame represented by the grayscale unit so that load effect correction is performed based on the average value. The brightness of each subfield-determined by the number of sustains.

In summary, the load effect prevention apparatus according to the present embodiment described above,

① Obtain average value of loads for each subfield forming the previous frame

② The average value (fixed) is used as a reference for preventing the load effect of the current frame.

In the end, a fixed average value is presented as a reference for removing the load effect, and the average value is a value that is different from the calculated value (tabled) used in the continuous image in the case of the PDP. .

As described above, the apparatus and method for preventing a load effect according to the present invention uses a separate value obtained by averaging values of loads for each subfield forming a previous frame as a reference for preventing a load effect of a current frame. do.

Through this, flicker in the still image, which has been a problem in the past, can be prevented, and the user can satisfy the reliability of the entire product.

Claims (8)

A gradation unit for expressing gradation of one frame in a plurality of sub fields in a still picture; And A correction unit for separately obtaining an average value of loads for each of the subfields of the previous frame, and adjusting the gray level of the frame represented by the gray level unit to perform a load effect correction based on the average value Load effect prevention device comprising a. The method of claim 1, And 10 to 12 subfields constituting the frame. The method of claim 1, The gradation unit for each subfield An address unit for selecting a cell to emit light; Sustain section which determines the light emission sustain time of the cell selected in the address section by the number of sustains Load effect prevention device comprising a. The method of claim 1, The corrector comprises: an average value extractor for calculating an average value of loads for each subfield of a previous frame; A sustain adjusting unit which performs load effect correction of each subfield of the current frame by adjusting the number of sustains based on the average value extracted by the average value extracting unit. Load effect prevention device comprising a. Plasma display panel (PDP) equipped with the load effect prevention apparatus of any one of Claims 1-4. In the method for preventing a load effect generated when the still picture of the plasma display panel is represented, Separately obtaining an average value of loads for each of the plurality of subfields forming the previous frame; Performing a correction of a load effect on a subfield of a current frame corresponding to a still picture based on the average value by adjusting the number of sustains of the subfield Load effect prevention method comprising a. The method of claim 6, The sub-field is 10 to 12, characterized in that the load effect prevention method. The method of claim 6, The sustain number is a load effect prevention method, characterized in that it has a range of 0 to 12.

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