AC等離子顯示面板中光環型邊界殘影的實驗研究-韓國電子工程dissertation  Experimental Study on Halo-Type Boundary Image Sticking

in 42-in. AC Plasma Display Panel

Choon-Sang Park and Heung-Sik Tae

School of Electrical Engineering and Computer Science, Kyungpook National University,

1370 Sankyuk-Dong, Buk-Gu, Daegu, 702-701, Korea

Young-Kuk Kwon, Seung Beom Seo, Eun Gi Heo, Byung-Hak Lee, and Kwang Sik Lee

R&D Team, PDP Division, Samsung SDI Co., Ltd. Korea

Abstract

When displaying the square-type image with peak luminance for about 500 hours in 42-in. PDP-TV with high Xe (15 %) content, the luminance and IR (828 nm) emission of the non-discharge region adjacent to the discharge region were observed in comparison with the discharge region and non-discharge region far away from the discharge region, under the two different image patterns, such as the dark and full white backgrounds.  http://ukthesis.org/Thesis_Writing/Accounting_Assignment/Engineering/  特別是，鹵素型邊界相鄰的放電區域的非放電區域中觀察到影像殘留。 In

particular, the halo-type boundary image sticking was observed in the non-discharge region adjacent to the discharge region. Under the dark background, the IR was initiated the fastest and the luminance was the highest in the regions adjacent to the discharge region, whereas under the full white background, the IR was initiated the fastest in the region adjacent to the discharge region but its luminance was higher than that of the discharge region and lower than that of the region far away from the discharge region. 素型的邊界影像殘留現象是由于MgO和熒光體層的MgO對相鄰的放電區域，這一點通過Vt靠近曲線，Mg的檔案中，在非放電區域的再沉積SEM分析證實。The halo-type boundary image sticking phenomenon is due to the re-deposition of the MgO on both the MgO and phosphor layers in the non-discharge region adjacent to the discharge region, which is confirmed by the Vt close curve, Mg-profile and SEM analyses.
 

1. Introduction

One of issues related with the image quality in an AC PDP is image sticking problem. In particular, the sticking problem tends to become serious as the Xe partial pressure increases. Although the iterant strong sustain discharge during a sustain-period is known to induce an image sticking problem, the image sticking phenomenon is not still fully understood [1, 2, 3, 4]. Especially, the cause for an image sticking phenomenon in the non-discharge region adjacent to the discharge region is not clear. This paper

focuses on examining the boundary image sticking, that is, an image sticking phenomenon in the non-discharge region adjacent to the discharge region, and finding its culprit. In this paper, the luminance and IR (828 nm) emission of the non-discharge region adjacent to the discharge region were observed in comparisonwith the discharge region and non-discharge region far away from the discharge region, under the two different image patterns, such as the dark and full white backgrounds, when displaying the square-type image with peak luminance for about 500 hours in 42- in. PDP-TV with high Xe (15 %) content.#p#分頁標題#e#

2. Halo-type Boundary Image Sticking Pattern

Fig. 1 shows the commercial 42-in. ac-PDP module with a boxtype barrier rib and the optical-measurement systems employed in Fig. 1. Schematic diagram of experimental setup. this experiment. The color analyzer (CA-100 plus), imaging colorimeter (Prometric PM Series), pattern generator, signal generator and the photo-sensor amplifier (Hamamatsu, C6386) were used to measure the luminance of the local region and entire region, IR emission and Vt close curve, respectively. To produce the halo-type boundary image sticking, the entire region of the 42- inch panel was changed to the dark and full white background images immediately after the square-type image with peak

luminance was displayed for about 500 hours. The driving method with a selective reset waveform was adopted. The frequency for the sustain-period was 200 kHz, and the sustain voltage was 206V.

The gas chemistry in the experiment was Ne-Xe (15%)-He (35%). Fig. 2 shows that the luminance difference among the regions, A(discharge region), B(non-discharge region adjacent to the discharge region), and C(non-discharge region far away from the discharge region) was observed under the dark background and full-white background images after the iterant 500 hours strong sustain discharge. As shown in Fig. 2 (a), the image sticking occurred in the regions A and B. Under the dark background produced only by the weak reset discharge, the luminance of the discharge region A, i.e., image sticking cells was observed to be higher than that of the non-discharge region C. In particular, the non-discharge region adjacent to the discharge region, i.e., boundary region, showed the highest luminance, and its shape appeared a kind of bright circle. Resultantly, the region B is called ‘the halo-type boundary image sticking under dark background’.

Fig. 2. Image sticking pattern under (a) dark background and (b) full-white background where region A is discharge region, region B is non-discharge region adjacent to discharge region, and region C is non-discharge region far away from discharge region captured from 42-in. panel.

As shown in Fig. 2 (b), the image stickings occurred in the regions, A and B. Unlike the dark background, the luminance in region B was lower than that of region C, even though it was higher than that of region A, under the full white background. The region B is called ‘the halo-type boundary image sticking under the full white background’.

3. Experimental Results of Halo-type

Boundary Image Sticking in 42-in. AC-PDP Fig. 3 shows the changes in the IR (828 nm) emissions measured from the regions A, B, and C during the reset period under the

dark background produced only by the weak reset discharge. The IR peaks in the regions A and B were observed to be shifted to the left in comparison with that in the region C, indicating that the weak reset discharge was initiated efficiently at a lower starting discharge voltage during the reset period. In particular, the halotype boundary image sticking region (B) showed the fastest IR emission and highest luminance. 由于在復位放電的點火斜坡期間的電壓降低可以是誘導的影像殘留的罪魁禍首，主要影響因素電在復位電放期間需要詳細研究。Since the reduction of a firing voltage in the reset discharge during a ramp period may be a culprit for inducing an image sticking, the main factor affecting the reset discharge during the reset period need to be investigated in detail.#p#分頁標題#e#

Fig. 4 shows the changes in the IR (828nm) emissions measured from the regions A, B, and C during the sustain-period to investigate the IR emission characteristics under the full-white background. The IR emission data in Fig. 4 shows that the IR peaks in the region B was shifted to the left, which illustrated the same tendency as that of the reset discharge under the dark background. However, the luminance in region B was lower than that of region C, which illustrated the different tendency from that

of the reset discharge under the dark background.

In order to investigate the main reason for the discrepancy of the IR emission and luminance characteristics in the region B under the dark and full-white backgrounds, the Vt close curve was Fig. 3. Comparisons of IR (828nm) emissions measured from regions A, B, and C during reset period under dark background.

Fig. 4. Comparisons of IR (828nm) emissions measured from regions A, B, and C during sustain period under full-white background. measured in the three regions, A, B, and C. As shown in Fig. 5, the firing voltages in the sides, V(Y-A) and VI(X-A), that is, the firing voltages under the phosphor cathode condition, were decreased remarkably, whereas the firing voltages in the sides,I(X-Y), II(A-Y), III(A-X), and IV(Y-X), that is, the firing voltages under the MgO cathode condition, were decreased slightly. Table 1 shows the detailed changes in firing voltage value measured from the regions A, B, and C. In region A, the reduced voltages in the firing voltage in the Y-A and X-A discharge were about 100 and 80 V, respectively, whereas in region B, the reduced voltages in the firing voltage in the Y-A and X-A discharge were about 10-15 and 5-10 V, respectively. It is thought that the reduction of the firing voltage in the plate gap discharge is due to the deposition of MgO onto the phosphor layers, which is caused by the sputtering of the MgO induced by the iterant strong sustain discharge. Accordingly, the Vt close curve results show that the decrease in the luminance in region A is attribute to the prohibition of the visible conversion from the VUV of the phosphor layers caused by the MgO deposition onto the phosphor layers instead of the deterioration of the phosphor Fig. 5. Comparison of Vt close curves measured from regions A, B and C without initial wall charges where I : VtXY(=Discharge start threshold cell voltage between X and Y), II :

VtAY (=Discharge start threshold cell voltage between A and Y), III : VtAX (=Discharge start threshold cell voltage between A and X), IV : VtYX (=Discharge start threshold cell voltage between Y and X), V : VtYA (=Discharge start threshold cell voltage between Y and A), and VI : VtXA (=Discharge start threshold cell voltage between X and A).

Table.1. Difference of firing voltage measured from regions A,B, and C.#p#分頁標題#e#

Cathode VI 258V 324V 332V layer itself. Furthermore, it appears that the reduction of the luminance in region B is due to the deposition of MgO onto the phosphor layer, and the fast IR initiation in region B is also due to the deposition of MgO onto the MgO layer. This re-deposition of MgO onto both the MgO and phosphor layers is the main reason

for the halo-type boundary image sticking in region B.

For the identification of the MgO re-deposition, the SEM and Mgprofile analyses were measured. Fig. 6 shows the comparisons of SEM image captured from regions A, B, and C. Although the region B is non-discharge area, the morphology of region B is similar to that of the discharge region, i.e., region A. The change in the morphology of the MgO surface in the region B is presumably due to the re-deposition of the MgO induced by the sputtering of the MgO made by the iterant strong sustain

discharge in the discharge region A adjacent to the non-discharge region B. B區MgO的陰極的條件下擊發電壓下降，這表示再沉積的MgO有助于降低點火電壓As shown in Table 1, the firing voltages are decreased in region B under the MgO cathode condition, which means that the re-deposition of MgO contributes to lowering the firing voltage.

Region C Region B Region A
Fig. 6. Comparisons of MgO surface SEM image measured from regions A, B, and C. Fig. 7 shows the comparisons of Mg-profile on the red phosphor layer measured from the regions A, B, and C where the Mgprofile means the intensity of the Mg sputtered with time from the red phosphor layer when the Ar ions strike the surface of the red

phosphor layer. As shown in Fig. 7, the Mg intensity in the regions A and B were observed to be shifted upward in comparison with that in the region C, indicating that the Mg was re-deposited onto the phosphor layer. The Mg species sputtered were dominantly re-deposited in the discharge region A, whereas the Mg species sputtered were slightly re-deposited even in the non-discharge region B adjacent to the discharge region A. The re-deposition of Mg on the phosphor layer much affects the discharge characteristics especially under the phosphor cathode condition. Therefore, the firing voltage in the region A where the Mg species sputtered were dominantly re-deposited was the lowest, as shown in the Vt close curve analysis. Furthermore, the firing voltage in the region B where the Mg species sputtered were slightly re-deposited was lower than that of the nondischarge region C where the Mg species sputtered were not redeposited.

It is concluded that the re-deposition of Mg onto both the MgO layer and phosphor layer can contributes to the enhancement of the discharge characteristics such as a firing voltage, IR emission,but the re-deposition of Mg onto the phosphor layer deteriorates the conversion efficiency of the phosphor layer from VUV into visible, thus resulting in lowering the luminance.#p#分頁標題#e#

Fig. 7. Comparisons of Mg-profile on the red phosphor layer  measured from regions A, B, and C.

4. Conclusion

The sticking problem tends to become serious as the Xe partial pressure increases. Thus, the image sticking needs to be solved urgently for the realization of a high image quality in AC-PDP.However, the image sticking phenomenon has not been exactly understood so far. In particular, the cause for the halo-type boundary image sticking phenomenon in the non-discharge region adjacent to the discharge region is not clear. Vt靠近曲線實驗結果，根據掃描電鏡（SEM）和Mg的剖面分析，鹵代-型邊界影像殘留現象的主要原因是MgO和熒光體層上的再沉積的MgO。As a result of the Vt close curve, SEM and Mg-profile analyses, the main reason for the halo-type boundary image sticking phenomenon is the redeposition of MgO onto both the MgO and phosphor layers. It is expected that this experimental result can contribute to eliminating the halo-type boundary image sticking of the PDPTV.

5. References

[1] Heung-Sik Tae, Jin-Won Han, Sang-Hun Jang, Byeong-No Kim, Bhum Jae Shin, Byung-Gwon Cho, and Sung-Il Chien, “Experimental observation of image sticking phenomenon in AC plasma display panel,” IEEE Trans. Plasma Science,Vol. 32, No. 6, pp.2189-2196, 2004.

[2] Jin-Won Han, Heung-Sik Tae, Sung-Il Chien, and Bhum Jae Shin, “Experimental study on temperature-dependent characteristics of temporal dark boundary image sticking in 42 in. AC-PDP,” SID’05 Digest, pp.1036-1039, 2005.

[3] Choon-Sang Park, Byung-Gwon Cho, Jin-Won Han, Heung- Sik Tae, Sung-Il Chien, Dong Ho Lee, and Bhum Jae Shin,“Driving waveform for removing temporal dark image

sticking in AC plasma display panel,” IDW/AD’05 Digest,pp.1465-1468, 2005.

[4] Tadayoshi Kosaka, Koichi Sakita, and Keiichi Betsui, “Firing voltage fluctuation phenomenon caused by gas density nonuniformity in PDPs,” IDW/AD’05 Digest,