KR20020089875A - Method for prolonging useful life of plasma panel display by dynamically adjusting input video signal strength - Google Patents

Abstract

PURPOSE: A method for extending the effective life time of a plasma panel display by dynamically adjusting the intensity of an input video signal is provided to exclude the bad affection such as a change of color temperature or a color deflection of the plasma display panel caused by the augment of lifetime by dynamically adjusting the intensity of the video signal. CONSTITUTION: A method for extending the effective life time of a plasma panel display(PDP) by dynamically adjusting the intensity of an input video signal includes the steps of: dynamically adjusting the intensity of each of the input video signals of a red, a green and a blue discharging cells of the PDP after the PDP is used during a predetermined time, emitting a red, a green and a blue lights from the red, the green and the blue discharging cells and for compensating the reduction of the emission rate per each gray scale related to the fluorescence layer of each of the discharging cells contributing to the augment of the lifetime of the red, the green and the blue lights.

Description

METHOD FOR PROLONGING USEFUL LIFE OF PLASMA PANEL DISPLAY BY DYNAMICALLY ADJUSTING INPUT VIDEO SIGNAL STRENGTH}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to plasma display panels (PDPs) and, more particularly, to dynamic color temperature and color deflection correction methods for improving the image quality appearing on a PDP.

A method of manufacturing a conventional AC discharge plasma display panel (PDP) 10 is shown in FIG. First, two different activation layers are formed on the glass substrates 11 and 12, respectively. The perimeters of the glass substrates 11 and 12 are then sealed together. A mixed gas consisting of helium (He), neon (Ne), and xenon (Xe) (or argon (Ar)) having a predetermined mixing volume ratio is stored in the discharge space formed between the glass substrates 11 and 12. The front plate 11 is configured as one of the yura substrates 11 and 12 facing the viewer. A plurality of parallel spaced transparent electrodes 111, a plurality of parallel spaced bus electrodes 112, a dielectric layer 113, and a protective layer 114 are formed inwardly from the front plate 11. Inwardly from the corresponding backplate 12, a plurality of parallel spaced data electrodes 121, a dielectric layer 124, a plurality of parallel spaced ribs 122, and a uniform phosphor layer 123 are formed. When a voltage is applied to the electrodes 111, 112, and 121, the dielectric layers 113 and 124 discharge to the discharge cells 13 formed of adjacent spaced ribs 122. As a result, light rays with the desired color are emitted from the phosphor layer 123.

Traditionally, the PDP 10 has a front plate by sputtering and optical processing (or printing).

The transparent electrodes 111 having a plurality of parallel intervals are formed on the inner surface of the (11). Next, the plurality of parallel spaced bus electrodes 112 are formed on the transparent electrodes 111 by plating (or sputtering) and photoetching, respectively. The line impedance of the transparent electrodes 111 may be reduced by the provision of the bus electrodes 112. In the following description, two adjacent electrodes 111 (including bus electrodes 112) on the front plate 11 are described as X electrodes and Y electrodes, respectively. Three electrodes are formed by the X electrode, the Y electrode, and the corresponding data electrode 121 on the back plate 12. When a voltage is applied to the three electrodes, the dielectric layers 113 and 124 discharge to the discharge cells 13 formed by the adjacent spaced ribs 122. Therefore, ultraviolet rays are emitted from the mixed gas stored therein. In turn, the phosphor layer 123 in the discharge cell 13 is activated by ultraviolet rays. Finally, visible light is generated by the red, green and blue phosphor layers, ending with the image display.

However, in the conventional plasma display panel (PDP) 10 as shown in Fig. 2, the emissivity of the phosphor layer 123 composed of red, green, and blue light is a function of time. In other words, the phosphor layer 123 The emissivity of is lowered as the use time increases. The degree of degradation depends on the characteristics (eg, material) of the phosphor layer 123. However, the drop inevitably shortens the effective time of the PDP 10 and thus causes color temperature change (ie, degradation) and color deflection. With regard to the above-described color temperature drop, color deflection, and poor image quality occurring in the conventional PDP 10, no effective solution has been proposed by the PDP manufacturer so far. Therefore, it is desirable to provide a novel method of extending the useful life of a PDP in order to overcome the above disadvantages of the prior art.

Therefore, an object of the present invention is to perform experiments on red, green, and blue phosphor layers respectively coated on corresponding discharge cells in order to calculate the gain per gray scale for the phosphor layer of each discharge cell. Establishing a comparison table of gains by acquiring an expression to describe the relationship; Allow the control circuit of the PDP to select one of the gains from the comparison table based on the usage time to dynamically adjust the intensity of the input video signal of each discharge cell; The effective lifetime of the plasma display panel (PDP), which consists of steps of compensating for the brightness of the reduction per gray scale with respect to the phosphor layer of each discharge cell due to the increase in the use time by the red, green and blue light of each emission, is shown. To provide a way to extend. This compensates for the emissivity of the reduction, eliminating adverse effects such as shortening of lifespan, color temperature changes, and color deflections caused by the emissivity of the reduction. As a result, an image with an optimal color purity and color temperature is given, thus improving the useful life of the PDP.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken in the accompanying drawings.

1 is a flowchart illustrating a method for extending the useful life of a PDP according to the present invention;

2 is a cross-sectional view of a conventional PDP.

Typically, an image appearing on a known PDP consists of a plurality of pixels. In addition, the number of pixels is determined by the resolution of the PDP. The pixel is composed of three discharge cells capable of emitting red, green, and blue light, respectively. As such, the color of the pixels of the image appearing on the PDP is simply a combination of red, green, and blue light emitted by each discharge cell. For example, a, b, and c are gray scales of red, green, and blue light emitted by each discharge cell of each pixel of the PDP. R _p , G _p , and B _p are the brightness emitted by the unit gray scale of the phosphor layer of the red, green, and blue discharge cells of each pixel. Thus, the brightness of the red, green, and blue discharge cells may be represented by the following equations 1, 2 and 3:

Brightness of the red discharge cell = aR _p (1);

Brightness of green discharge cell = bG _p (2); And

Brightness of blue discharge cell = cB _p (3).

In addition, the brightness of the pixel is represented by the following equation 4:

Brightness of pixel = Brightness of red discharge cell + Brightness of green discharge cell + Brightness of blue discharge cell

= aR _p + bG _p + cB _p (4).

In addition, the ratio between the brightness of the red, green, and blue discharge cells is also expressed by Equation 5:

Brightness of red discharge cell: Brightness of green discharge cell: Brightness of blue discharge cell

= aR _p : bG _p : cB _p (5).

As described above, the emissivity of the phosphor layer of the PDP decreases as the use time increases. The brightness of the decrease per gray scale of the red, green, and blue discharge cells of the PDP due to the increased usage time is k _R R _p , k _G G _p , and k _B B _p , but k _R <1, k _{And G} <1, and k _B <1. Therefore, the brightness of each of the red, green, and blue discharge cells and the pixel after prolonged use may be represented by Equations 6, 7, 8, and 9, respectively:

Brightness of the red discharge cell = ak _R R _p (6);

Brightness of rust discharge cell = bk _G G _p (7);

Brightness of the blue discharge cell = ck _B B _p (8); And

Brightness of pixel = Brightness of red discharge cell + Brightness of green discharge cell + Brightness of blue discharge cell

= aR _p + bG _p + cB _p (9).

In addition, the ratio between the brightness of the red, green, and blue discharge cells may be expressed by the following equation (10):

Brightness of red discharge cell: Brightness of green discharge cell: Brightness of blue discharge cell

= ak _R R _p : bk _G G _p : ck _B B _p (10).

In comparison between Equations 5 and 10, it is found that the ratio between the brightness of the red, green, and blue discharge cells is changed, which in turn causes color deflection. It is also found that the degree of decreasing the brightness of the blue discharge cell is the largest among the discharge cells, ending with the reduction of the color temperature of the PDP.

One aspect of the present invention is to improve the emissivity of the reduction per gray scale of each discharge cell due to the increase in the use time to eliminate adverse effects such as color temperature change and color deviation of the PDP caused by the increase in use time. Therefore, red, green and blue phosphor layers coated on corresponding discharge cells are used in the experiment as detailed in the flowchart of FIG. 1. First, the emissivity of the decrease per gray scale with respect to the phosphor layer of each discharge cell due to the increase in the use time of the PDP is analyzed. Thus, the temperature function is used to calculate the gain per gray scale (e.g., α _i , β _i , or γ _i ) for each of the red, green, and blue phosphor layers of the discharge cells. The equations describing their relationship with each other are obtained as follows:

t _i <T <t _{i + 1} → α _i

t _i <T <t _{i + 1} → β _i

t _i <T <t _{i + 1} → γ _i

T _i and t _{i + 1} are the upper and lower limits of each time period and T is the usage time. Therefore, a comparison table is established with reference to the above data. Therefore, the control circuit of the PDP can select one of the gains α _i , β _i , and γ _i from the comparison table based on the usage time in order to dynamically adjust the input video signal strength of each discharge cell. Each of the red, green and blue light is then emitted from the respective discharge cells. The lights are used in turn to compensate (i.e. increase) the emissivity of the reduction per gray scale of each discharge cell due to the increase in the use time, thereby effectively reducing the lifetime, color temperature variation and color deflection of the PDP caused by the emissivity of the reduction. Eliminate adverse effects such as shortening. The result is an image with optimal color purity and color temperature. Most importantly, the useful life of the conventional PDP is greatly improved by implementing the method of the present invention.

In one embodiment of the present invention, a technique is proposed to solve the brightness of the reduction of each discharge cell of the PDP resulting from an increase in the use time. In detail, after a predetermined usage time, the control circuit of the PDP obtains one of the gains α _i , β _i , and γ _i from the comparison table based on the usage time T to dynamically adjust the input video signal strength of each discharge cell. You can choose. As a result, the red, green and blue light emitted from the discharge cells are changed. The light of the change is used to compensate (ie increase) the emissivity of the decrease per gray scale of each discharge cell due to the increase in the use time. The ratio between the gains α _i , β _i , and γ _i of the compensation is expressed by the following equations (11) and (12):

α _i : β _i : γ _i = k _G k _B : k _R k _B : k _R k _G (11)

max (α _i , β _i , γ _i ) ≤ 1 (12)

In addition, the red, green, and blue discharge cells and the brightness of the pixel after compensation may be expressed by Equations 13, 14, 15, and 16, respectively:

Brightness of the red discharge cell after compensation = (ak _{R ai} ) R _p (13);

Brightness of the green discharge cell after compensation = (bk _G β _i ) G _p (14);

Brightness of the blue discharge cell after compensation = (ck _B γ _i ) B _p (15); And

Brightness of pixel after compensation = Brightness of red discharge cell after compensation + Brightness of green discharge cell after compensation + Brightness of blue discharge cell after compensation

= (ak _R α _i ) R _p + (bk _G β _i ) G _p + (ck _B γ _i ) B _p (16).

In view of Equations 11 to 16, the ratio between the brightness of red, green and blue discharge cells after compensation can be expressed by Equation 17 below:

Brightness of red discharge cell after compensation: Brightness of green discharge cell after compensation: Brightness of blue discharge cell after compensation = aR _p : bG _p : cB _p (17).

Comparison of Equations 17 and 5 finds that the ratio between the brightness of the red, green and blue discharge cells returns to the true ratio, ending with the total exclusion of the adverse effects caused by the emissivity of the reduction of the phosphor layers.

In another embodiment of the present invention, a technique is proposed to solve the brightness of the decrease per gray scale of each of the red, green and blue discharge cells of the PDP due to the increase in the use time. In detail, the brightness of each of the red, green, and blue discharge cells and the pixel is represented by the following equations 18, 19, 20, and 21, respectively:

Brightness of the red discharge cell = a (R _p -T _R ) (18);

Brightness of the green discharge cell = b (G _p -T _G ) (19);

Brightness of the blue discharge cell = c (B _p -T _B ) 20; And

Brightness of pixel = Brightness of red discharge cell + Brightness of green discharge cell + Brightness of blue discharge cell

= aR _p + bG _p + cB _p -aT _R -bT _G -cT _B (21);

However, aT _R , bT _G , and cT _B are the brightness of the reduction of the respective red, green, and blue discharge cells due to the increase in the use time. The brightness of the decrease may also cause adverse effects such as the effective life of the PDP, color temperature change and shortening of the color deflection. One feature of the present invention is to improve the emissivity of the reduction per gray scale of each discharge cell due to the increase in the use time, thereby eliminating adverse effects such as color temperature and color deflection of the PDP caused by the increase in use time. . Therefore, the red, green and blue phosphor layers coated on the corresponding discharge cells are used for the experiment as detailed in the flowchart of FIG. First, the emissivity of the decrease per gray scale with respect to the phosphor layer of each discharge cell resulting from the increase of the usage time of PDP is analyzed. The temperature function is then used to calculate the brightness of the reduction per gray scale (e.g., T _Ri, T _Gi and T _Bi ) for each of the red, green, and blue phosphor layers of the discharge cells. Their relationship to cell usage time is described below:

t _i <T <t _{i + 1} → T _Ri

t _i <T <t _{i + 1} → T _Gi

t _i <T <t _{i + 1} → T _Bi

T _i and t _{i + 1} are the upper and lower limits of each time period and T is the usage time. Therefore, a comparison table is established with reference to the above data. In addition, the control circuit of the PDP can select one of T _Ri , T _Gi , and TB _i from the comparison table based on the usage time in order to dynamically adjust the input video signal strength of each discharge cell. Each of the red, green and blue light is then emitted from the respective discharge cells. The lights are used in turn to compensate (i.e. increase) the emissivity of the reduction per gray scale of each discharge cell due to the increase in the service time and the effective lifetime, color temperature change and color deflection of the PDP caused by the emissivity of the reduction. Eliminate adverse effects such as shortening. The result is an image with optimal color purity and color temperature. Most importantly, the useful life of the conventional PDP is greatly improved by implementing the method of the present invention.

Any of the above embodiments of the present invention is provided to solve the brightness of the reduction of each discharge cell of the PDP due to the increase in the use time. After a predetermined use time, the control circuit of the PDP can select one of T _Ri , T _Gi , and TB _i from the comparison table based on the use time T to increase the intensity of the input video signal of each discharge cell. As a result, red, green and blue light emitted from the discharge cells are increased. This increase is used in turn to compensate (ie increase) the emissivity of the decrease per gray scale of each discharge cell due to the increase in the use time.

In addition, based on the results of the experiment, such as T _Ri , T _Gi , and TB _i , the brightness of the decrease per gray scale for each discharge cell due to the increase in the use time can be expressed by the following equations 22, 23, and 24. have.

T _Ri = k _Ri R _p (22);

T _Gi = k _Gi G _p (23); And

TB _i = k _Bi B _p (24);

Where T _Ri , T _Gi and TB _i are the brightness compensation coefficients obtained by trials. In addition, ak _Ri , bk _Gi , and ck _Gi increase the brightness for the red, green, and blue discharge cells. Thus, the discharge cells of compensation and the brightness of the pixel can be represented by the following equations 25, 26, 27 and 28, respectively:

Brightness of the red discharge cell after compensation = a (1 + k _Ri ) R _p -aT _Ri (25);

Brightness of the green discharge cell after compensation = b (1 + k _Gi ) G _p -bT _Gi (26);

Brightness of the blue discharge cell after compensation = c (1 + k _Bi ) B _p -cT _Bi (27); And

Brightness of compensating posterior pixel = brightness of red discharge cell after compensation + brightness of green discharge cell after compensation + brightness of red discharge cell after compensation = aR _p + bG _p + cB _p (28).

In short, the method of the present invention compensates (i.e. increases) the emissivity of the reduction per grayscale of each discharge cell due to the increase in the use time, thereby adversely affecting the color temperature change and color deflection of the PDP caused by the increase in the use time. Can be excluded by dynamically adjusting the input video signal strength. The result is an image with optimal color purity and color temperature. Most importantly, the useful life of the conventional PDP is greatly improved.

Having described the invention by means of specific embodiments, many modifications and variations may be made by those skilled in the art without departing from the scope and spirit of the invention as set forth in the claims.

Claims (4)

In a plasma display panel (PDP), a method for extending the useful life thereof (a) dynamically adjusting the intensity of each input video signal of the red, green and blue discharge cells of the PDP after a predetermined usage time; (b) emitting red, green and blue lights from the red, green and blue discharge cells; (c) utilizing the red, green and blue light of the radiation to compensate for the emissivity of the decrease per gray scale for the phosphor layer of each discharge cell due to the increase in the service time, The method consists of steps. The method of claim 1, In step (c) (c1) In order to calculate the gain per gray scale of the phosphor layer of each discharge cell, an experiment is performed on the red, green, and blue phosphor layers respectively coated on the corresponding discharge cells, and then at the usage time of each discharge cell. Establishing a comparison table for the gains by obtaining equations to describe the relation in relation to the gains; (c2) allow the control circuit of the PDP to select one of the gains from the comparison table based on the usage time to dynamically adjust the intensity of the input video signal of each of the discharge cells; (c3) compensating for the brightness of the decrease per gray scale for each phosphor layer of each of the discharge cells due to an increase in the service time by each of the red, green and blue light of the emission, A PDP life extension method further comprising auxiliary steps. The method according to claim 1 or 2, And the gain per gray scale for the phosphor layer of each discharge cell is time dependent. The method according to claim 1 or 2, And the gain per gray scale for the phosphor layer of each discharge cell is a value that depends on the use time and the material forming the phosphor layer.