WO2005057542A1

WO2005057542A1 - Apparatus and method of driving plasma display panel

Info

Publication number: WO2005057542A1
Application number: PCT/KR2004/003282
Authority: WO
Inventors: Hwan Yu Kim; Dae Jin Myoung; Geun Soo Lim; Jun Hak Lee; Jung Hwan Kim
Original assignee: Lg Electronics Inc.
Priority date: 2003-12-15
Filing date: 2004-12-14
Publication date: 2005-06-23
Also published as: KR100551122B1; KR20050059520A

Abstract

The present invention relates to an apparatus and method of driving a plasma display panel in which a signal distortion can be minimized. The driving apparatus of a plasma display panel of the present invention comprises a first gamma correcting unit for performing a first inverse gamma correction of data supplied from the exterior; a gradation-processing unit performing a gradation-processing of the first inverse gamma-corrected data; and a second gamma correcting unit for performing a second inverse gamma correction of the gradation-processed data.

Description

APPARATUS AND METHOD OF DRIVING PLASMA DISPLAY PANEL

Technical Field The present invention relates to an apparatus and method of driving a plasma display panel, and more particularly, to an apparatus andmethod of driving a plasma display panel in which a signal distortion can be minimized.

Background Art According to the development and spread of an information processing system, an importance of a display device being visual information transmitting means is being increased. Cathode Ray Tube (CRT) , which is used as most of the display devices, has a disadvantage of large-sizing, high operation voltage and display distortion. Recently, a flat display device such as Liquid Crystal Display (LCD) , Field Emission Display (FED) and Plasma Display Panel (PDP) for solving the disadvantage of the CRT is being developed. The PDP uses a vacuum ultraviolet ray, which is generated at the time of discharging an inert mixing gas, to excite phosphor and emit light, thereby displaying an image. The PDP has an advantage of not only easy slimness and large-sizing, but also easy manufacture caused by its simple structure and also, a high luminance and efficiency of light emission. In particular, an alternate-current surface discharge type PDP has an advantage of low-voltage driving and a long lifetime since a wall discharge is stored at a surface at the time of discharge and electrodes are protected from sputtering caused by the discharge. Referring to FIG. 1, the alternate-current surface discharge type PDP includes a front glass substrate 1 having an upper electrode 9; and a rear glass substrate 2 having an address electrode 4. The front glass substrate 1 and the rear glass substrate 2 are spaced apart in parallel with each other, and a barrier rib 3 is interposed between the front glass substrate 1 and the rear glass substrate 2. Mixing gas such as Ne+Xe, He+Xe, and He+Ne+Xe is injected into a discharge space, which is provided by the front glass substrate 1, the rear glass substrate 2 and the barrier rib 3. The upper electrode 9 is paired within one plasma discharge channel. Each of the upper electrodes 9 includes a transparent electrode with a large width; and a metal bus electrode with a small width. The metal bus electrode is connected to an edge and at one side of the transparent electrode. Any one of the paired upper electrodes 9 being a scan electrode performs a facing discharge with the address electrode 4 in response to a scan pulse supplied for an address period and then, performs a surface discharge with an adjacent upper electrode 9 in response to a sustain pulse supplied for a sustainperiod. Further, the other upper electrode 9 paired with the scan electrode is a sustain electrode for jointly supplying the sustain pulse. An upper dielectric layer 7 and a passivation film 8 are layered on the front glass substrate 1 having the upper electrodes 9. The upper dielectric layer 7 functions to limit a discharge current at the time of plasma discharge and also store the wall charge at the time of discharge. The passivation film 8, which is generally formed of oxide magnesium (MgO) , prevents the upper dielectric layer 7 from being damaged due to the sputtering generated at the time of the plasma discharge and enhances a radiation efficiency of a secondary electron. A lower dielectric layer 6 is formed on the rear glass substrate

2 to cover address electrodes 4. The lower dielectric layer 6 functions to protect the address electrodes 4. The barrier ribs are formed on the lower dielectric layer 6 to divide the discharge space. The phosphor 5 is formed on surfaces of the lower dielectric layer 6 and the barrier ribs 3 to be excited by the vacuum ultraviolet ray, thereby generating a visible ray of red (R) , green (G) and blue (B) . A discharge mechanism of the PDP is as follows. If a voltage is applied between two electrodes of the PDP, a potential is formed within the discharge space. As gas atoms and molecules are collided and ionized by the potential, the discharge is caused within the pixel . The charged particles generated by the gas discharge are piled up on the surface of the dielectric layer 7 depending on an electrode polarity. Negative charges andpositive charges piledup on the surface of the dielectric layer 7 are called the wall charge, and a pixel voltage charged by the wall charge is called the wall voltage. If the wall charge sufficiently piled up on the surface of the dielectric layer 7 has an opposite polarity to an external voltage applied to the electrode, the wall voltage and the external voltage are offset with each other while the discharge is erased. If the wall voltage and the external voltage have the same polarity due to the opposite polarity of the external voltage, a total voltage applied to the discharge space is a sum of the external voltage and the wall voltage. If the voltage is larger than a discharge initiation voltage, the discharge is generated within the pixel. In order to embody a gradation of the image, the PDP is time-division driven in so called an Address and Display Separated (ADS) where the address period for which the pixel is selected and the sustain period for which the display discharge is generated at a selected pixel. That is, one frame period is divided into a few of sub-fields at which a sustain discharge time is differently set depending on a luminance weighted value, and each sub-field is divided into a reset period, the address period and the sustain period. For example, in case where the image is displayed using 256-level gradation, a frame period (16.67ms) corresponding to 1/60 second is divided into eight sub-fields (SFl to SF8) as shown in FIG. 8. Each of the eight sub-fields (SFl to SF8) is divided into the reset period, the address period and the sustain period as described above. The reset period and the address period of each sub-field are identical with each other every sub-field, whereas the number of the sustain period and the sustainpulse assignedto the sustain period is increased in a proportion of 2ⁿ (n=0, 1, 2, 3, 4, 5, 6, 7) at each sub-field. FIG. 3 is a block diagram schematically illustrating the PDP and its driving apparatus . In actual, the PDP additionally includes a variety of driving units in addition to driving units of FIG. 3.

Here, only main driving unit is shown for description convenience. Referring to FIG.3, a conventional PDP driving apparatus includes a gamma correcting unit 30, an error diffusion & dithering processing unit 32, a sub-field mapping unit 33, and a data driving unit 34. The PDP 37 includes a sustain electrode pair (that is, upper electrodes 9) having a scan electrode and a sustain electrode; and an address electrode intersecting with the sustain electrode pair. At an intersection of the sustain electrode pair and the address electrodes, discharge cells are arranged in matrix format. Video data (R, G, B) supplied from the exterior is inputted to the sub-field mapping unit 33 through the gamma correcting unit 30 and the error diffusion & dithering processing unit 32. The gamma correcting unit 30 performs an inverse gamma correction of red, green and blue video data to linearly convert a luminance value depending on a gradation value of the video data. For example, the gamma correcting unit 30 divides a current input value by a maximum input value, and then performs 2.2 of gamma multiplication of the divided value to correct the data. The error diffusion & dithering processing unit 32 uses Floyd-Steinberg error diffusion filter and the like to diffuse a component of quantization error of the digital video data (R, G, B) , which is inputted from the gamma correcting unit 30, to an adjacent pixel to reduce the quantization error and provide a minute gradation expression. Further, the error diffusion & dithering processing unit 32 criticalizes the input data by using a dither mask (or dither matrix) having a set threshold value corresponding to each pixel. The sub-field mapping unit 33 maps the data of the error diffusion & dithering processing unit 32 to a predetermined sub-field pattern. The data driving unit 34 latches the mapped data of the sub-field mapping unit 33 and supplies each one line of the latched data to the address electrodes of the PDP 37 at each of one horizontal period. The scan driving unit 35 is connected to the scan electrode of the PDP 37 to supply a necessary signal to the scan electrode, thereby driving the scan electrode. The sustain driving unit 36 is connected to the sustain electrode of the PDP 37 to supply a necessary signal to the sustain electrode, thereby driving the sustain electrode. However, the conventional PDP driving apparatus causes a distortion of an original signal . In detail describing this, the video data (R, G, B) inputted from the exterior is inverse gamma-corrected in the gamma correcting unit 30. After that, the inverse gamma-corrected data can be gradation-processed and supplied to the PDP 37 to be displayed through the PDP 37. Here, since the inverse gamma-corrected data different from the original signal (original data) is usedfor the gradationprocessing, thatis, since data different from the original data is used to perform the gradation processing, the distortion of the displayed image of the PDP is caused, that is, there is a little difference between the displayed image and a desired image of the original data. In actual, the inverse gamma-corrected data using a 2.2 gamma curve i s used to perform the gradation processing, an expression of a low gradation is deteriorated.

Disclosure of Invention

An object of the present invention is to provide an apparatus andmethod of driving a plasma displaypanel in which a signal distortion can be minimized. The driving apparatus of a plasma display panel of the present invention comprises a first gamma correcting unit for performing a first inverse gamma correction of data supplied from the exterior; a gradation-processing unit performing a gradation-processing of the first inverse gamma-corrected data; and a second gamma correcting unit for performing a second inverse gamma correction of the gradation-processed data. The second gamma correcting unit performs the inverse gamma correction by using a higher gamma value than in the first gamma correcting unit. The first gamma correcting unit performs the first inverse gamma correction of the inputted data with a gamma value of 1.1 to 1.2. The gamma value of the second gamma correcting unit is set to provide a total of 2.2 of the second inverse gamma correction value and. the first inverse gamma correction value . The gradation-processing unit includes at least one of an error diffusion unit performing an error diffusion and a dithering processing unit. A driving apparatus of a plasma display panel of the present invention comprises a first gamma correcting unit for performing a first inverse gamma correction of data supplied from the exterior; a gradation-processing unit performing a gradation-processing by using the first inverse gamma-corrected data; and a sub-field mapping unit for mapping the gradation-processed data according to a sub-field pattern and performing a second inverse gamma correction of the data. The sub-field mapping unit performs the inverse gamma correction by using a higher gamma value than in the first gamma correcting unit. The first gamma correcting unit performs the first inverse gamma correction of the inputted data with a gamma value of 1.1 to 1.2. The gamma value of the sub-field mapping unit is set to provide a total of 2.2 of the second inverse gamma correction value and the first inverse gamma correction value. The gradation-processing unit includes at least one of an error diffusion unit performing an error diffusion and a dithering processing unit. A driving method of a plasma display panel of the present invention comprises a step of performing a first inverse gamma correction of data supplied from the exterior; a step of gradation-processing the first inverse gamma-corrected data; and a step of performing a second inverse gamma correction of the gradation-processed data. In the step of performing the second inverse gamma correction, an inverse gamma correction is performed by using a higher gamma value than in the step of performing a first inverse gamma correction. In the step of performing a first inverse gamma correction, data supplied from the exterior is inverse gamma-corrected with a gamma value of 1.1 to 1.2. In the step of performing a second inverse gamma correction, data supplied from the exterior is inverse gamma-corrected with a gamma value of 2.2, which is a total value including the inverse gamma value of the first inverse gamma correction step. In the step of gradation-processing, the first inverse gamma-corrected data is gradation-processed by using at least one method of an error diffusion process and a dithering process. Brief Description of Drawings

FIG. 1 is a perspective view illustrating a conventional three electrode AC surface discharge typed plasma display panel; Fig. 2 is a view illustrating one frame of the plasma display panel; Fig. 3 is a view illustrating a conventional driving apparatus of a plasma display panel; and Fig. 4 is a view illustrating a driving apparatus of a plasma display panel according to an embodiment of the present invention.

Best Mode for Carrying Out the Invention Hereinafter, referring to Fig. 4, a preferable embodiment of the present invention will be described. Fig. 4 is a view showing a driving apparatus of the plasma display panel according to the present invention. In actual, a Plasma Display Panel (PDP) includes a variety of driving units in addition to the driving unit of Fig. 4. Here, for description convenience, only main driving unit is shown. With reference to Fig. 4, the driving apparatus of the PDP of the present invention includes a first gamma correcting unit 40; an error diffusion & dithering processing unit 42; a second gamma correcting unit 44; a sub-field mapping unit 46; and data driving unit 48, which are provided between an input line and the PDP 50. The PDP 50 includes a sustain electrode pair including a scan electrode and a sustain electrode, and an address electrode intersecting with the sustain electrode pair. At an intersection of the sustain electrode pair and the address electrodes, discharge cells are arranged in matrix format. Video data R,G,B supplied from the exterior are input to the first gamma correcting unit and the error diffusion & dithering processing unit 42, where a gradation is performed. And then the video data is input to the address electrodes of the PDP 50 via the second gamma correcting unit 44, the sub-field mapping unit 46 and the data driving unit 48. The first gamma correcting unit 40 performs a first inverse gamma correction of the red, green and blue video data R, G, B. Herein, the first gamma correcting unit 40 performs a gamma correction of 1.1 to 1.2 with the original data R, G, B to minimize a distortion of the original data. In other words, first gamma correcting unit 40 performs an inverse gamma correction of the original data R, G, B to prevent a distortion of the original data. The error diffusion & dithering processing unit 42 diffuses an error value of data corresponding to the gradation to an adjacent pixel to reduce the quantization error and performs a minute gradation expression. In addition, the error diffusion & dithering processing unit 42 criticalizes the input data by using a dither mask (or dither matrix) having a predetermined threshold value corresponding to each pixel. Meanwhile, in this embodiment, an error diffusion process and a dithering process are concurrently performed for a description convenience, but only any one of the error diffusion process and the dithering process can be performed. The gradation-processed data R, G, B by the error diffusion & dithering processing unit 42 are inputted to the second gamma correcting unit 44. The second gamma correcting unit 44 performs a second inverse gamma correction of the data R, G,B (At this process, the second gamma correcting unit 44 performs the second inverse gamma correction by using a gamma value higher than in the first gamma correcting unit 40) . Here, the second gamma correcting unit 44 performs the second inverse gamma correction of the data R, G, B to provide a total of 2.2 of the first inverse gamma correction value and the second inverse gamma correction value. In other words, the inverse gamma correction value of the second gamma correcting unit 44 is set up to allow the gamma correction value of the original data R,G,B to be 2.2. Meanwhile, in the present invention, the second inverse gamma correction may be performed by a sub-field mapping unit 46. In other words, the sub-field mapping unit 46 can perform the second inverse gamma correction the gradation-processed data R,G,B by the error diffusion & dithering processing unit 42. As explained above, in the present invention, the first inverse gamma correction is performed to prevent a distortion of data supplied from the exterior (or to minimize the distortion) , and a gradation-processing is performed by using the first inverse gamma-corrected data. Accordingly, the driving apparatus of PDP of the present invention can minimize a distortion of the original signal to display the same image as the original data on the PDP 50. In other words, since a first inverse gamma-corrected data, which is similar to an original signal (an original data) , is used for the gradation-processing, a minimally distorted data is used for the gradation, thereby clearly displaying a desired image on the PDP 50. The sub-field mapping unit 46 maps the second gamma-corrected data to a predetermined sub-fieldpattern. Here, the sub-fieldmapping unit 46 can perform the second inverse gamma correction of the gradation-processed data, which is inputted from the error diffusion & dithering processing unit 42, and in this case the second gamma correcting unit 44 is removed. The data driving unit 48 latches the sub-field mapped data and provides each one line of the latched data to the address electrodes of the PDP 50 at each one horizontal period. A scan driving unit 52 is connected to scan electrodes of the PDP 50 and drives the scan electrodes by providing signal required for the scan electrodes. A sustain driving unit 54 is connected to sustain electrodes of the PDP 50 and drives the sustain electrodes by providing signal required for the sustain electrodes . As described above, in an apparatus and method of driving a plasma display panel according to the present invention, the first inverse gamma-corrected data with a gamma of 1.1 to 1.2 is gradation-processed to minimize a distortion of an original data. In addition, the gradation-processed data is second inverse gamma-corrected to provide 2.2 gamma of a total inverse gamma correction value, and then the second inverse gamma-corrected data is provided to the panel, thereby clearly displaying an original data on the panel.

Claims

What Is Claimed Is:

1. A driving apparatus of a plasma display panel, the apparatus comprising: a first gamma correcting unit for performing a first inverse gamma correction of data supplied from the exterior; a gradation-processing unit performing a gradation-processing of the first inverse gamma-corrected data; and a second gamma correcting unit for performing a second inverse gamma correction of the gradation-processed data.

2. The apparatus as set forth in claim 1, wherein the second gamma correcting unit performs the inverse gamma correction by using a higher gamma value than the gamma value of the first gamma correcting unit.

3. The apparatus as set forth in claim 1, wherein the first gamma correcting unit performs the first inverse gamma correction of the inputted data in a gamma value of 1.1 to 1.2.

4. The apparatus as set forth in claim 3, wherein the gamma value of the second gamma correcting unit is set in 2.2 gamma that is a sum the inverse gamma correction value of the first gamma correction unit and the second gamma correction unit

5. The apparatus as set forth in claim 1, wherein the gradation-processing unit includes at least one of an error diffusion unit which performs error diffusion and a dithering processing unit which performs dithering.

6. A driving apparatus for a plasma display panel, the apparatus comprising: a first gamma correcting unit for performing a first inverse gamma correction of data supplied from the exterior; a gradation-processing unit performing a gradation-processing by using the first inverse gamma-corrected data; and a sub-field mapping unit for mapping the gradation-processed data according to a sub-field pattern and performing a second inverse gamma correction of the data.

7. The apparatus as set forth in claim 6, wherein the sub-field mapping unit performs the inverse gamma correction by using a higher gamma value than the gamma value of the first gamma correcting unit.

8. The apparatus as set forth in claim 6, wherein the first gamma correcting unit performs the first inverse gamma correction of the inputted data in a gamma value of 1.1 to 1.2.

9. The apparatus as set forth in claim 8, wherein the gamma value of the sub-field mapping unit is set in 2.2 gamma that is a sum the inverse gamma correction value of the first gamma correction unit and the sub-field mapping unit

10. The apparatus as set forth in claim 6, wherein the gradation-processing unit includes at least one of an error diffusion unit which performs error diffusion and a dithering processing unit which performs dithering.

11. A driving method of a plasma display panel, the method comprising: a step of performing a first inverse gamma correction of data supplied from the exterior; a step of gradation-processing the first inverse gamma-corrected data; and a step of performing a second inverse gamma correction of the gradation-processed data.

12. The method as set forth in claim 11, wherein, in the step of performing the second inverse gamma correction, the inverse gamma correction is performed by using a higher gamma value than the value in the step of performing the first inverse gamma correction.

13. The method as set forth in claim 11, wherein, in the step of performing the first inverse gamma correction, the data supplied from the exterior is inverse gamma-corrected in a gamma value of 1.1 to 1.2.

14. The method as set forth in claim 13, wherein, in the step of performing the second inverse gamma correction, the data supplied from the exterior is inverse gamma-corrected in a gamma value of 2.2, which is a total value including the inverse gamma value of the first inverse gamma correction step.

15. The method as set forth in claim 11, wherein, in the step of gradation-processing, the first inverse gamma-corrected data is gradation-processed by using at least one method of an error diffusion process and a dithering process.