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Discussion Starter · #1 ·
KURO TECHNOLOGY EXPLAINED


Thread created as a reference thread to be a primer for the zero black thread . It will be linked in the first post of that thread.


I have used mostly verbal explanations of KURO technology over the last 4 years as to not break any copyright laws. I have recently received permission to use selected charts and graphs with proper reference for teaching purposes. Do not mess with copyright!!!



Patent application # 20080068304 - describes KURO technology including cell material design and driving waveform changes. (source D-Nice)


KURO technology involves two primary technologies that enable very deep black levels (MLL):
  • MgO crystals on top of or imbedded into the phosphor layer
  • Spatial discharge to initialize the panel (also to produce low light emission in first subfield)


Below is a detailed description of both technologies along with Pioneer data, charts, graphs.

MgO Crystals on top or imbedded into the phosphor layer


Every single conventional PDP display ever made has evaporated MgO on the top of the cell (see graphic below). This MgO serves two important purposes
  • MgO has high sputter resistance and thus protects the dielectric and electrode materials from high energy ions (ie – protects them from damage)
  • MgO has a relatively high secondary electron emission (gamma) which ejects electrons into the discharge space to enable the cell to turn off and on faster and operate at lower voltages.




Reference #4 p. 107.



In 2004/2005 Pioneer developed something they call CEL – crystal emissive layer that is single crystal MgO cubes that they spray onto the regular MgO evaporated layer.


This CEL-MgO greatly enhances the secondary and exo-electron emission and also emits intense UV light at 235nm which augments the excitation of the phosphor producing higher brightness. Pioneer used a combination of evaporated MgO and CEL-MgO to create the first 1080p PDP ever and class leading efficiency. However, black levels were still behind Panasonics REAL-BLACK system.


Then Pioneer developed a method to place the CEL-MgO material on top of the phosphor layer itself (or imbedded inside it) and things changed dramatically.


Now the cell had 3 MgO layers (1 evaporated layer, 2 CEL-MgO layers (top and bottom of cell). See graphic below.




Reference #2 p. 273



This enabled long lasting priming electron emission at both the Address and scan electrodes (see graphic below).




Patent app#20080068304



This in turn enables stable high speed operation even with extremely small initialization discharge (black level) to the point where only a weak spatial discharge was enough to initialize the cell (see next section)

Spatial discharge to initialize the panel (also to produce low light emission in first subfield)


As described above the CEL-MgO on phosphor development enabled the use of spatial discharge to initialize the panel and even sustain the first subfield (emit low levels of picture data).


Below is a graphic describing the difference between conventional surface discharge and KURO type spatial discharge. Notice how small and weak the initialization/reset (black level)discharge is compared to the surface type.



Reference #1 p. 278




Reference #1 p. 276




Below is the data Pioneer accumulated on the massive improvement in initialization (black level) discharge obtained by using weak spatial discharge.


Patent app#20080068304




Below is a more detailed graphic from Pioneer describing how spatial discharge is used to both initialize the panel (black level) and sustain the first subfield (low picture luminance)



Reference #3 p. 117



Below is a graph showing the improvement in black level (MLL) and the first subfield (low level picture luminance)




Reference #3 p. 117



References



1 - 21.2: Very High Contrast PDP Driving Method on Advanced CEL Cell Panel

Koji Hashimoto, Shunsuke Itakura, Tsutomu Tokunaga, Mitsuhiro Ishizuka, Shigeru Iwaoka, and Nobuhiko Saegusa

SID Symposium Digest 39 275 (2008) LINK


2 - 21.1: Advanced Discharge Cell Design with CEL Realizing Very High Contrast over 20000:1

Taro Naoi et al.

SID Symposium Digest 39 271 (2008) LINK


3 - Improved discharge characteristics using MgO single-crystal particles and advanced CEL structure

Taro Naoi, Hai Lin, Atsushi Hirota, Eishiro Otani, and Kimio Amemiya

J. Soc. Inf. Display 17 113 (2009) LINK


4 - High-contrast driving method for advanced CEL structure with magnesium oxide single-crystal powder in ACPDP

Koji Hashimoto, Shunsuke Itakura, Kazuaki Sakata, Tsutomu Tokunaga, Mitsuhiro Ishizuka, Shigeru Iwaoka, and Nobuhiko Saegusa

J. Soc. Inf. Display 17 107 (2009) LINK
 

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Thank you for your efforts in presenting this material. The following portion of the patent application discusses how utilization of the magnesium oxide single crystals allow increasing intensity of pdp and improves dark contrast due to reset discharges being performed at a center (spaced away from the panel face) reducing the light emissions. Very interesting. The paragraph [0132] below has nice explanation.


[0042] According to such a drive, at the reset discharges, cations within the discharge gas collide against the secondary electron emission material in advancing toward the side of the column electrodes, and they emit secondary electrons into the discharge space. The discharge initiation voltage of the pixel cells becomes low owing to a priming action based on such secondary electrons, and hence, comparatively weak reset discharges can be induced. Consequently, owing to the weak reset discharges, a light emission intensity involved in the discharges lowers, so that a display in which a dark contrast is enhanced can be presented. Further, the reset discharges are induced between the row electrodes on one side, formed on the side of the front transparent substrate and the column electrodes formed on the side of the rear substrate.


[0043] Therefore, discharge light which is externally emitted from the side of the front transparent substrate becomes less than in a case where the reset discharges are induced between the row electrodes both of which are formed on the side of the front transparent substrate, so that further enhancement in the dark contrast can be attained. Besides, immediately after the address step of the head subfield as stated above, a voltage with the row electrodes on one side, in the row electrode pairs set as an anode side and the column electrodes set as a cathode side is applied between both the electrodes, thereby to induce minute light emission discharges between the column electrodes and the row electrodes on one side within the pixel cells being in the states of the light-up mode. Since the minute light emission discharges are generated between the row electrodes on one side, in the row electrode pairs formed on the side of the front transparent substrate and the column electrodes formed on the side of the rear substrate, a light emission intensity involved in the discharges is lower than in sustain discharges which are generated between the row electrodes formed on the side of the front transparent substrate. In other words, it is permitted to represent an intensity level which is lower than an intensity level that is visually recognized in a case where the sustain discharges are induced only once. Therefore, the intensity difference between gradations representing low intensities becomes smaller, so that a gradation representation capability in the case of representing a dark image is heightened.


[0132] Further, in general, in a PDP, also reset discharge incurs light emissions. The light emissions ascribable to the reset discharge have no relation to the gradation display of an image. Therefore, when the light emissions ascribable to the reset discharge are recognized at a panel face in case of displaying an image of intensity "0", or the like, the dark contrast of the image lowers. In contrast, in the PDP of the embodiment, the reset discharge is performed by the opposed discharges between the row electrodes Y and the column electrodes D, and the opposed discharges occur at the central parts of the discharge cells C spaced from the panel face (the surface of the front glass substrate 10). Accordingly, when the PDP of the embodiment is compared with the case where the reset discharge is performed by the surface discharges between row electrodes at positions near the panel face, the light emissions ascribable to the reset discharge as are recognized at the panel face become less, so that the dark contrast of the image to be displayed can be enhanced.


[0139] In addition, with the PDP, as shown in FIG. 5, the CL emission MgO crystals mixed in the fluorophor layer 17 are arranged at the positions of the surface of the fluorophor layer 17 exposed to the interior of the discharge cells C, whereby the initial electrons can be emitted into the discharge cells C efficiently without being hampered by fluorophor grains contained in the fluorophor layer 17. Therefore, the discharge initiation voltage of the address discharge can be lowered more.


[0151] Since the PDP shown in FIGS. 1 through 4 has the CL emission MgO crystals contained as the MgO crystals 17B and mixed in the fluorophor layer 17, it has the effect of enhancing the intensity of the PDP, in addition to the effect of enhancing the dark contrast as stated above.
 

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Discussion Starter · #6 ·
Thanks Jonsey11,


I posted the patent text here in the past along with verbal explanations but I'm not sure many people like to read patents like we do
I tried to explain it in simpler terminology in the first post with some easy to understand graphics. The patent definitely has more detail for those interested in further understanding.


Just so everyone doesn’t get confused I can try and relate the somewhat different terminology of the patent to the terminology used in the first post. Also, anyone may feel free to ask me if you want a more laymans description of anything in the patent or first post.


Paragraphs [0042] and [0043] describe secondary electron emission and spatial discharge for the initialization and 1st subfield. This is all described in the first post (see figures 8 for picture of spatial discharge X-A versus surface dischareg X-Y)


Note: Pioneer calls spatial discharge "opposed discharge" as the electrodes are opposite to each other (facing each other).

Quote:
Originally Posted by Pioneer patent app#20080068304 /forum/post/0


[0132] Further, in general, in a PDP, also reset discharge incurs light emissions. The light emissions ascribable to the reset discharge have no relation to the gradation display of an image. Therefore, when the light emissions ascribable to the reset discharge are recognized at a panel face in case of displaying an image of intensity "0", or the like, the dark contrast of the image lowers. In contrast, in the PDP of the embodiment, the reset discharge is performed by the opposed discharges between the row electrodes Y and the column electrodes D, and the opposed discharges occur at the central parts of the discharge cells C spaced from the panel face (the surface of the front glass substrate 10). Accordingly, when the PDP of the embodiment is compared with the case where the reset discharge is performed by the surface discharges between row electrodes at positions near the panel face, the light emissions ascribable to the reset discharge as are recognized at the panel face become less, so that the dark contrast of the image to be displayed can be enhanced.

[0132] (quoted above) - describes how generating spatial discharge vs surface discharge inherently reduces light output (blacker blacks) based on the location of the discharge (centre of cell vs surface of cell). This is not mentioned in post#1 because I don’t quite agree with it because the phosphor is at the bottom of the cell anyway??? The only way I see this reducing light emission is by reducing visible light emission from the MgO itself (cathodoluminescence emission above 400nm – blue light).


If you guys can explain it better to me then I might understand it better??

Quote:
Originally Posted by Pioneer patent app#20080068304 /forum/post/0


[0139] In addition, with the PDP, as shown in FIG. 5, the CL emission MgO crystals mixed in the fluorophor layer 17 are arranged at the positions of the surface of the fluorophor layer 17 exposed to the interior of the discharge cells C, whereby the initial electrons can be emitted into the discharge cells C efficiently without being hampered by fluorophor grains contained in the fluorophor layer 17. Therefore, the discharge initiation voltage of the address discharge can be lowered more.

[0139](quoted above) - describes placement of MgO on surface of phosphor (as opposed to mixed in the phosphor) to enable ejected electrons to easily enter the open cell.

Quote:
Originally Posted by Pioneer patent app#20080068304 /forum/post/0


[0151] Since the PDP shown in FIGS. 1 through 4 has the CL emission MgO crystals contained as the MgO crystals 17B and mixed in the fluorophor layer 17, it has the effect of enhancing the intensity of the PDP, in addition to the effect of enhancing the dark contrast as stated above.

[0151](quoted above) -description in that paragraph may confuse the heck out of some people without context. Like I describe in the first post, unlike normal vacuum deposited MgO the fancy CEL-MgO (single crystal type MgO) has strong UV emission when impacted by high energy particles. As you know, plasma phosphor is excited by UV from the gas discharge. So the presence of CEL-MgO augments the amount of UV generated which in turn increases the amount of light generated by the phosphors.


Basically:
Regular MgO – emits electrons under ion impact
CEL MgO – emits electrons and UV light under ion and electron impact (CL – cathodoluminescence)
Normal PDP cell - generates most UV through discharge of the gas
KURO PDP cell - generates UV through gas discharge and cathodoluminescence of the CEL MgO. As mentioned in the first post the UV generated by the MgO is relatively low wavelength 200+nm.
 
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Discussion Starter · #7 ·
Also just to clarify:


The primary reason that the blacks are blacker when using CEL-MgO is that the intense secondary electrons that it emits dramatically reduce the discharge delay and increases discharge probability for an extended period of time. In laymans terms the excess electrons produced using this material enable the gass in the cell to be ionized extremely easily even when the cell has been off for a relatively long while. This means the cell can be initialized with very weak discharges only once per frame and we all know that means very low black level.


I will clarify this in the first post later.


But look at the amazing probability data:


No MgO - 0.1

Evaporated MgO (every PDP has) - 2.3

Multple crystal MgO (ie - CEL - MgO) - 89.3


This is also a good way to not ever need floating blacks
 
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Quote:
Originally Posted by specuvestor /forum/post/19592406


Thanks much xrox. So the million $ question to panny & pio fans are: is this CEL technology 1) difficult or 2) costly to implement in panny's fab?

I thought Panny was using something like this on the VX100. The "dynamic black layer" they called it.
 

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All this makes you feel that owning a Pioneer KRP-500M is something extra. If Panasonic gets rid of floating blacks and implement absolute blacks next year(i hope..), I think Pioneer owners can be proud over the King of plasmas.
 

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Quote:
Originally Posted by trem0lo
Awesome post!! Any explanation as to why the 500m & 101 have slightly deeper blacks than other Pioneer 9g panels? Just a more efficient implementation of the CEL technology?
yes, I think it's time.. I had to wait for at least 18 months to post (for inventories to clear out and other reasons). Enjoy!



Quote:
about deeper black of KRP-500M/PRO-101FD,,,,


50 inch monitor's black level is slightly deeper than any other.


first of all, basically two reasons


1) production facility


Panel of our monitor of 50 inch are made in Kagoshima Plant, which has

latest facility of us. other panels are made in either Shizuoka or Kofu.


our Kagoshima panel has latest equipment and better than other facility.

In reality, Kagoshima's plen performs better than others.



2) unevenness of mass production

our black level is very dark and tough to control the black level for all

models, all lots. so sometimes, due to production lots, some panel's black level is deeper

than other.



the difference of chassi No, is production is from the reason of 1).


if we mixture of impact of both 1) and 2), at worst case (or best case) you will see big difference.


Our official comment is our panel performance is same for all

products/panels, but the above is reality,



Oh, technology itself is totally same between all panels.

just the preciseness of crystal emissive layer is different.


Kagoshima plant can paste that layer better than other.


crystal emissive layer is fundamental and key technology for breakthrough into KURO.

how precise we can paste is the key.

 
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What does posting that information have to do with inventory?
 

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Thanks for de-mystifying the Kuro breakthroughs. What a treat it is every time that I get to enjoy the fantastic picture.
 

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it’s very sad for me seeing such a feat being withdrawn. i have 2 pioneer panels, a 9th gen and a 6th gen and both have an amazing picture. No technology after 2 years comes close to it when it comes to black level. As for processing the circuitry is designed to be as faithful as possible to the source!
 

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As a patent attorney, I don't mind reading patents. Thank you for the analysis.


Very interesting....I wonder how hard it would be for Panny, whom I believe bought Pioneer's IP including, presumably, trade secrets, to implement the Kuro technology in their displays. Any thoughts?
 

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Thanks for clarifying Turbe, I was wondering why the 500M was darker. And thanks xrox for you clarification of my post.


Now I wonder why Panny can't do the same. Is their panel structure/ adressing so different that the Kuro tech is not compatible? Or is it a cost issue? Anyone know?
 

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Discussion Starter · #20 ·

Quote:
Originally Posted by specuvestor /forum/post/19599857


ie the million $ question still goes unanswered :p

Right now I can't give you a solid answer.


However, I have again read through the patent and the papers again and will have to edit the first post as there are some inaccurate interpretations I made. Anyway please read some new info below which I will edit into the first post later.
  • The patent describes how the CEL material is formed. A special form of vapour oxidation of Mg metal. The powder product can then be spray coated onto the panel surface or solution coated in IPA (Isopropyl alcohol).

  • Pioneer claims that extra step of forming the CEL material onto the phosphor does not raise the cost very much as long as the equipment for producing CEL type MgO and coating it is in place.

  • The “CL” or cathodoluminescence of the CEL material is only a property claim in the patent used to characterize the material. In the actual KURO panel the CEL material uniqueness is that it has strong UV photoluminescence at 235nm (wrong in first post) along with the excess long lasting emission of secondary electrons (correct in first post).

  • The CEL material on phosphor blocks visible light which means that if too much is used the panel efficiency drops
 
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