fast addressing of plasma display panels vladimir nagorny plasma dynamics corp

Fast Addressing of Plasma Fast Addressing of Plasma Display PanelsDisplay Panels

Vladimir NagornyVladimir Nagorny

Plasma Dynamics Corp.Plasma Dynamics Corp.


Addressing SpeedAddressing Speed

Frame (16.7Frame (16.7msms) ) ≥≥10 10 SubfieldsSubfields Reset ~ 300Reset ~ 300ss ·10 ·10 3 3msms Address ~ 1-1.5Address ~ 1-1.5s/line s/line

(best)(best) 5-7.5ms (500 5-7.5ms (500 lines)lines) 10-15ms 10-15ms (1000 lines) (1000 lines)

Sustain (Variable time)Sustain (Variable time)

Unless addressing Unless addressing speed better speed better (<1ms/line)(<1ms/line) Single Scan Single Scan

Low Resolution, or dim Low Resolution, or dim imageimage

High Resolution High Resolution Dual ScanDual Scan


How to make addressing faster?How to make addressing faster?

To answer this question one should first To answer this question one should first answer other questions:answer other questions:

Q1: How does address discharge work?Q1: How does address discharge work?

Q2: Which factors control/limit its speed?Q2: Which factors control/limit its speed?

Q3: Are there any alternative ways to make Q3: Are there any alternative ways to make addressing faster?addressing faster?


Q1: Starting point for addressingQ1: Starting point for addressing Reset Period

VbX

Y

V AY

V XY

XY

AY

AX

XA

(sustain gapdischarge)

VA

Assume that at the end of the reset Assume that at the end of the reset period both SG and PG discharges are period both SG and PG discharges are active, and ramp is stable. This can be active, and ramp is stable. This can be verified by measuring the Vt-curve (K. verified by measuring the Vt-curve (K. Sakita, et al., SID2001; H. Kim, et. al., Sakita, et al., SID2001; H. Kim, et. al., SID2001; S.T. de Zwart and B. Salters, SID2001; S.T. de Zwart and B. Salters, IDW2001). IDW2001).

Vt-curve is analog of the breakdown Vt-curve is analog of the breakdown voltage in 1D case and 2 electrodes. It voltage in 1D case and 2 electrodes. It positions applied voltages with respect positions applied voltages with respect to discharge conditions inside the cell, to discharge conditions inside the cell, since it shows where the balance since it shows where the balance between production of charged particles between production of charged particles and their losses is. and their losses is.

It doesn’t tell, though, anything about It doesn’t tell, though, anything about the discharge, when one applies a vector the discharge, when one applies a vector V which takes the cell off the balance.V which takes the cell off the balance.


Q1:Vt-curve – what it is and what it is Q1:Vt-curve – what it is and what it is notnot

What it is:What it is: Vt-curve depends on the wall charge surface Vt-curve depends on the wall charge surface distributiondistribution, which is not uniform and depends on real , which is not uniform and depends on real

parameters of a cell, discharge “history”, trajectory (Vparameters of a cell, discharge “history”, trajectory (VXYXY(t), V(t), VAYAY(t)) rather than final V(t)) rather than final VXYXY, V, VAYAY Vt-curve Vt-curve

transformstransforms (Figs. below) (Figs. below) it has to be it has to be measuredmeasured in every “critical” operation-wise point (after sustain in every “critical” operation-wise point (after sustain period, before and after ramps UP and Down, AFTER address discharge) otherwise actions one takes period, before and after ramps UP and Down, AFTER address discharge) otherwise actions one takes may have undesirable results. may have undesirable results.

What it isn’t:What it isn’t: As in 1D case and 2 electrodes the knowledge of the breakdown voltage gives only the reference point As in 1D case and 2 electrodes the knowledge of the breakdown voltage gives only the reference point

for comparison with voltage across the gap, the Vt-curve serves only as a reference line for 3 electrode for comparison with voltage across the gap, the Vt-curve serves only as a reference line for 3 electrode system, but it doesn’t give any information about the dynamics and the speed of the discharge.system, but it doesn’t give any information about the dynamics and the speed of the discharge.

When Va is applied, the field lines reconnect and conditions in the gap change completely. For When Va is applied, the field lines reconnect and conditions in the gap change completely. For example V=(example V=(VVXYXY, , VVAA)=(10, 70) from SIP doesn’t mean V)=(10, 70) from SIP doesn’t mean VXYXY becomes 10V above the breakdown (next becomes 10V above the breakdown (next

slide).slide).

0

0

F

VXY

VAY

1

2

3

0

0

1

2

3

4


Q1: Field reconfigurationQ1: Field reconfigurationEnd of the ramp case 1End of the ramp case 1 End of the ramp+Va(80V) case 1End of the ramp+Va(80V) case 1

End of the ramp case 2End of the ramp case 2 End of the ramp+Va(90V) case 2End of the ramp+Va(90V) case 2


Q1: Experiments with primingQ1: Experiments with primingVa=80V case 1 (3D Va=80V case 1 (3D PIC/MC)PIC/MC)After the ramp cell is emptied of After the ramp cell is emptied of all charges, address voltage all charges, address voltage applied and a weak source applied and a weak source (~1e/(~1e/s) imitating exoemission is s) imitating exoemission is placed either near the inner edge placed either near the inner edge or in the central part of the or in the central part of the cathode.cathode.

Emission from the edge does not Emission from the edge does not produce self-sustaining discharge produce self-sustaining discharge - it decays. - it decays.

Electron emitted in the center Electron emitted in the center produced ~4.5 times stronger produced ~4.5 times stronger avalanche than from the edge, avalanche than from the edge, and then number of particles and then number of particles increases with characteristic time increases with characteristic time ~ 43ns by itself. ~ 43ns by itself.


Q1: Summary of how discharge Q1: Summary of how discharge worksworks

Details depend on geometry, but in any case address discharge Details depend on geometry, but in any case address discharge comprises a few phases:comprises a few phases:

PrimingPriming – most likely by exoelectrons (unless external UV is present), – most likely by exoelectrons (unless external UV is present), and following amplification due to avalanches. and following amplification due to avalanches.

Fast growing Fast growing PG dischargePG discharge – source of electrons for ALL other – source of electrons for ALL other regions (due to electron diffusion), leading to growth of the regions (due to electron diffusion), leading to growth of the ion/current density everywhere, as the source (PG discharge) grows.ion/current density everywhere, as the source (PG discharge) grows.

SpreadSpread of the PG discharge and creating the SG “field channel”. of the PG discharge and creating the SG “field channel”. Depending on geometric parameters of the cell (SG vs. PG), SG Depending on geometric parameters of the cell (SG vs. PG), SG channel may be created sooner or later than PG discharge peaks. In channel may be created sooner or later than PG discharge peaks. In the latter case a strong PG discharge precedes SG discharge. the latter case a strong PG discharge precedes SG discharge.

Strong Strong SG dischargeSG discharge..

DecayDecay of a plasma due to mostly recombination after SG discharge. of a plasma due to mostly recombination after SG discharge.

It is SG discharge, which creates a large memory charge. It is SG discharge, which creates a large memory charge. Removing the scan voltage prior to plasma density decays will Removing the scan voltage prior to plasma density decays will result in lowering memory charge and may be even secondary result in lowering memory charge and may be even secondary discharge, erasing it.discharge, erasing it.


Q2: Controls/limitations of the Q2: Controls/limitations of the discharge speed?discharge speed?

Priming (statistical phase)Priming (statistical phase) Both exoemission rate, structure and strength of PG field (Va). Stronger Both exoemission rate, structure and strength of PG field (Va). Stronger

field, higher exoemission rate field, higher exoemission rate shorter delay. shorter delay.

PG dischargePG discharge Voltage across the gap, gap size ( Voltage across the gap, gap size ( ~L~L-2 -2 ) )

Creating the SG channelCreating the SG channel Mostly geometrical factors and capacitance of the dielectric near Mostly geometrical factors and capacitance of the dielectric near

address and sustain electrodes, Va. Channel can be created even at low address and sustain electrodes, Va. Channel can be created even at low Va, it will just take longer time, which makes the whole process Va, it will just take longer time, which makes the whole process analogous rather than digital.analogous rather than digital.

SG dischargeSG discharge Speed-no problem. Speed-no problem.

Decay (waste of time)Decay (waste of time) Mostly due to recombination. It requires ~0.5Mostly due to recombination. It requires ~0.5s, otherwise the memory s, otherwise the memory

charge will be reduced. Memory charge depends on actual applied charge will be reduced. Memory charge depends on actual applied voltage. No control of the decay time. voltage. No control of the decay time.


AlternativesAlternatives How about addressing How about addressing

more than one line at a more than one line at a time, achieving fast speed time, achieving fast speed for addressing a whole for addressing a whole panel rather than a single panel rather than a single line?line?

Can we make addressing Can we make addressing “digital”?“digital”?

What else can we do to What else can we do to accelerate addressing of a accelerate addressing of a single line, using what we single line, using what we have learned about the have learned about the discharge.discharge.

Movies - courtesy of Kenn Melvin: ourworld.compuserve.com/homepages/kennmelvin


Addressing the ON cellsAddressing the ON cells After SG discharge starts one can change the address voltage without After SG discharge starts one can change the address voltage without

any effect. The SG discharge IS a release button for the ON cells.any effect. The SG discharge IS a release button for the ON cells.

Memory charge differs by only 2% (actually better with the Memory charge differs by only 2% (actually better with the switch)switch)

If the cell is addressed ON, then one can apply the scan voltage If the cell is addressed ON, then one can apply the scan voltage and address the next line right after start of the SG discharge and address the next line right after start of the SG discharge without locking the line back, having large memory charge and not without locking the line back, having large memory charge and not wasting time for the decay. wasting time for the decay.


Addressing the OFF Addressing the OFF cellscells

One need to have PG discharge in OFF One need to have PG discharge in OFF cells to prevent them from being cells to prevent them from being addressed later on.addressed later on.

One can use different modes of the PG One can use different modes of the PG discharge for OFF (weak) and ON (strong) discharge for OFF (weak) and ON (strong) discharges. discharges.

OFF discharge being only PG discharge OFF discharge being only PG discharge can be made fast if PG is short and can be made fast if PG is short and voltage Va high. The higher voltage Va voltage Va high. The higher voltage Va (while discharge is weak, and no SG (while discharge is weak, and no SG channel formation) the better. channel formation) the better.

Natural geometry – short PG (T~LNatural geometry – short PG (T~L22), long ), long SG SG T TOFFOFF<T<TON ON (=T(=Tscan,minscan,min))

n

n'

k k'

ON OFF

ONON

t

t

t

t

scan,minT(n, k)

(n, k')

(n', k)

(n', k')

t

t

t

t

(n, k)

(n, k')

(n', k)

(n', k')

( 5 0 )

( 5 0 )

V AY

V XY

AY

AX

XA

VOFF


Dual Addressing, TDual Addressing, TOFF OFF <T<TONON

““Unlock the line”Unlock the line” “address ON “address ON andand OFF” OFF” “go to the next line” “go to the next line”

((TTaddraddr=T=TOFF OFF ))


Addressing: Short PGAddressing: Short PG

1. End of the Ramp Setup 2. Address voltage (60V) is applied

3. After OFF discharge (VOFF=50V) 4. Beginning of the ON discharge VON=60V, t=335ns


Parameters of Parameters of the OFF the OFF

dischargedischarge

Parameter /Va 30V 40V 50V 60V

Vgap, V 62 70 102 Break (ON)

, ns 270 155 118 xx

T(5000), ns 895 810 747 xx

Ni,max(105) 6.55 15 27.9 xx

Ttot, ns 770 680 472 xx


Short PG – ON dischargeShort PG – ON dischargeVVaddraddr=10V (V=10V (VONON=60V), First =60V), First

335ns335ns


TTOFFOFF>T>TONON : Advantages of Dual : Advantages of Dual AddressingAddressing

TTaddraddr=T=TONON (=T (=Tscan,minscan,min))

Larger VLarger VOFF OFF Lower VLower Vaddraddr (V (Vaddraddr=V=VONON-V-VOFFOFF), or ), or

higher possible Vhigher possible VONON

(combination of V(combination of VOFFOFF and and

common V’common V’addraddr): V): VONON=V’=V’addraddr+V+VOFFOFF

n

n'

k k'

ON OFF

ONON

t

t

t

t

scan,minT(n, k)

(n, k')

(n', k)

(n', k')

(n, k)

(n, k')

(n', k)

(n', k')

( 5 0 )

( 5 0 )

t

t

t

t

T scan,min

V AY

V XY

XY

AY

AX

XA

(sustain gapdischarge)

V OFF


Dual Addressing, TDual Addressing, TOFF OFF >T>TONON

“Unlock address ON and OFF lock go to the next line” (Taddr=TON )

TOFF>TON=Tscan,min PG is large,

Taddr=TON, Vaddr=VON - VOFF

In addition to VOFF bias, one may

decrease the voltage between

sustain electrodes (VXlock) in

order to obstruct the spread of

the discharge across SG (better

separate SG and PG discharges)

and maximize VOFF.

To maximize memory charge we

choose Vb,ramp higher than Vb by

VXlock. This is not necessary,

though.


SummarySummary Dual addressing with discharges in both ON and OFF cells has Dual addressing with discharges in both ON and OFF cells has

advantages, that come in one of three ways:advantages, that come in one of three ways: If parameters of a PDP cell allow one to achieve a fast OFF discharge If parameters of a PDP cell allow one to achieve a fast OFF discharge

(T(TOFFOFF<T<TONON=T=Tscan,minscan,min) then one can address the panel with T) then one can address the panel with TOFFOFF per line, per line,

using “Unlock the line”using “Unlock the line” “address ON and OFF” “address ON and OFF” “go to the next line” “go to the next line”

scheme.scheme.

If TIf TOFFOFF>T>TONON, then T, then Taddraddr=T=TONON, but one can either use a lower voltage for , but one can either use a lower voltage for

address drivers (Vaddress drivers (Vaddraddr=V=VON ON - V- VOFFOFF), or), or

Achieve a higher speed for the ON discharge and shorter TAchieve a higher speed for the ON discharge and shorter Taddraddr by by

combining conventional address drivers with large Vcombining conventional address drivers with large VOFFOFF bias. bias.

In any case TIn any case Taddraddr is smaller of T is smaller of TONON and T and TOFFOFF..

In a cell with short PG we obtained addressing time of ~650ns with In a cell with short PG we obtained addressing time of ~650ns with

VVaddraddr=10V, V=10V, VOFFOFF=50V.=50V.

In a cell with large PG (105-130um), TIn a cell with large PG (105-130um), TOFFOFF > T > TON ON T Taddraddr=T=TONON, and with , and with

VVXlockXlock~30-40V we obtained V~30-40V we obtained VOFFOFF>50V.>50V.

fast addressing of plasma display panels vladimir nagorny plasma dynamics corp

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