CN1998040A

CN1998040A - Plasma display device

Info

Publication number: CN1998040A
Application number: CNA2005800239967A
Authority: CN
Inventors: 池田敏; 山田义则; 足达克己; 西谷干彦; 后藤真志
Original assignee: Matsushita Electric Industrial Co Ltd
Current assignee: Panasonic Holdings Corp
Priority date: 2004-07-21
Filing date: 2005-07-05
Publication date: 2007-07-11
Anticipated expiration: 2025-07-05
Also published as: CN100433099C

Abstract

In a plasma display device, a lighting percentage is calculated from a video signal inputted into the plasma display device, and such an output current of a DC-DC converter (140) as is equal to the discharge current for a maintenance period corresponding to that lighting percentage is fed in synchronism with the generation timing of the discharge current. With this configuration, a maintenance pulse voltage can be kept constant even if the discharge current for the maintenance period of each subfield abruptly varies.

Description

Plasma display system

Technical field

The present invention relates to as big picture, thin and light display device and by known plasma display system.

Background technology

In recent years, large-scale popularizing of image display device such as plasma display system carried out.The trickle part that this large-scale image display device connects reflection can clearly show, but the reflection confusion that the spread of voltage of supplying with owing to power supply on the contrary etc. produce is also apparent in view.In order to prevent this evils, importantly the output voltage with the supply unit of image display device keeps constant.

Plasma display system comes display map by a plurality of discharge cells of being located at Plasmia indicating panel (being designated hereinafter simply as " PDP ").The discharge current of the PDP of this moment depends on that the gray-level value of shown reflection is many.And if gray-level value increases, then the discharge current of PDP increases, and opposite if gray-level value reduces, then discharge current reduces.

At the variation of this discharge current and make an example of the supply unit of the constant plasma display system of output voltage be disclosed in the spy to open 2002-351379 communique (hereinafter referred to as " patent documentation 1 ").This supply unit detects the variation of the output voltage that produces when discharge current changes, and carries out FEEDBACK CONTROL, so that output voltage is constant.

Yet the supply unit that patent documentation 1 is put down in writing returns to the control of original voltage after the variation that detects output voltage, therefore is difficult to make output voltage to keep constant under discharge current situation jumpy.

Summary of the invention

The present invention is the invention in order to address the above problem just, and its purpose is to provide a kind of plasma display system, even also can make output voltage keep constant under the discharge current of PDP situation jumpy and with correct gray-level value display map.

In order to address the above problem, the present invention is a kind of plasma display system, wherein during 1 (field) by during having an initialization, a plurality of sons formation during writing and during keeping, Plasmia indicating panel comprises having scan electrode, keep a plurality of discharge cells of electrode and data electrode, by discharge cell is discharged during keeping or do not discharge and on Plasmia indicating panel display map, this plasma display device comprises: keep the pulse voltage applying unit, it is to scan electrode and keep electrode and apply the pulse voltage of keeping that makes a plurality of discharge cells discharge usefulness; Light the rate calculating part, the rate of lighting of its discharge ratio of interior a plurality of discharge cells during keeping with regard to each son field calculating expression in advance by image signal; Power feeding section, it is to keeping pulse voltage applying unit supply capability; And control part, it is according to lighting rate, and the pulse voltage applying unit is kept in control, so that it is constant to keep pulse voltage.

Description of drawings

Fig. 1 is the exploded perspective view of structure of the PDP of expression embodiment of the present invention 1;

Fig. 2 is the figure of configuration of electrode of the PDP that is used for plasma display system of expression embodiment of the present invention 1;

Fig. 3 is the son figure that constitutes in 1 of plasma display system of expression embodiment of the present invention 1;

Fig. 4 is the figure of drive waveforms of the PDP of expression embodiment of the present invention 1;

Fig. 5 A is the figure that changes the time of the rate of lighting of each the son field in representing 1;

Fig. 5 B is the figure that changes the time of the rate of lighting of each the son field in representing 1;

Fig. 5 C is the figure that changes the time of the rate of lighting of each the son field in representing 1;

Fig. 5 D is the figure that changes the time of the rate of lighting of each the son field in representing 1;

Fig. 6 is the circuit diagram of power feeding section of the plasma display system of embodiment of the present invention 1;

Fig. 7 A is the figure of characterization curve, the rate of lighting and the output current of DC-DC converter and the relation of output voltage when this family curve represents that current controling signal is made as parameter;

Fig. 7 B is the figure that expression is used for the relation of rate of lighting that the output voltage maintenance of DC-DC converter is constant and current controling signal;

Fig. 8 is the circuit block diagram of the plasma display system of embodiment of the present invention 1;

Fig. 9 A is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 1;

Fig. 9 B is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 1;

Fig. 9 C is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 1;

Fig. 9 D is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 1;

Fig. 9 E is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 1;

Fig. 9 F is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 1;

Figure 10 is the circuit diagram of power feeding section of the plasma display system of embodiment of the present invention 2;

Figure 11 A is the figure of the relation of the expression second current controling signal Vadj and triangle wave voltage Trw and pwm signal Cmp;

Figure 11 B is the figure of the relation of the expression second current controling signal Vadj and triangle wave voltage Trw and pwm signal Cmp;

Figure 12 is the circuit block diagram of the plasma display system of embodiment of the present invention 2;

Figure 13 A is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 2;

Figure 13 B is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 2;

Figure 13 C is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 2;

Figure 13 D is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 2;

Figure 13 E is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 2;

Figure 13 F is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 2;

Figure 14 A is the figure that changes the time of expression primary side electric current with the relation of the output current of second current controling signal and DC-DC converter and output voltage;

Figure 14 B is the figure that changes the time of expression primary side electric current with the relation of the output current of second current controling signal and DC-DC converter and output voltage;

Figure 14 C is the figure that changes the time of expression primary side electric current with the relation of the output current of second current controling signal and DC-DC converter and output voltage;

Figure 14 D is the figure that changes the time of expression primary side electric current with the relation of the output current of second current controling signal and DC-DC converter and output voltage.

Among the figure: the sub-field transformation circuit of 104-, 120-lights the rate counting circuit, 130-storer, 140, the 141-DC-DC converter, 160-microcomputer, 172,182-keeps pulse voltage and apply circuit.

Embodiment

Followingly embodiments of the present invention are described with reference to accompanying drawing.

(embodiment 1)

Fig. 1 is the exploded perspective view of structure of the PDP1 that is used for plasma display system of expression embodiment of the present invention 1.PDP1 has the front substrate 2 and back substrate 3 of relative configuration.From front substrate 2 sides, in front on the front glass plate 4 of substrate 2, scan electrode 5 with keep electrode 6 parallel to each other in pairs and be formed with how right.And, form dielectric layer 7 to cover this scan electrode 5 with the mode of keeping electrode 6, form protective seam 8 in the mode that covers this dielectric layer 7.Form a plurality of data electrodes 10 parallel to each other on the back glass plate 9 of substrate 3 overleaf, form dielectric layer 11 in the mode that covers this data electrode 10.And, on the side in the surface of this dielectric layer 11 and next door 12, form luminescent coating 13.And then, in by the discharge space 14 of front substrate 2 and back substrate 3 clampings, enclose discharge gas.

Fig. 2 is the figure that the electrode of the PDP1 that is used for plasma display system of expression embodiment of the present invention 1 disposes.Arrange m column data electrode D1～Dm (data electrode 10 of Fig. 1) on line direction, (with the direction of row quadrature) alternately is arranged with the capable electrode SUS1～SUSn (Fig. 1 keep electrode 6) that keeps of n line scanning electrode SCN1～SCNn (scan electrode 5 of Fig. 1) and n on column direction.And, at a pair of scan electrode SCNi, ((j=1～m) clover leaf part forms discharge cell 24, and this discharge cell 24 is formed with m * n in discharge space with a data electrode Dj for i=1～n) to keep electrode SUSi.

Method as driving PDP1 adopts sub-field type.Sub-field type is that 1 field interval is divided into a plurality of sons field, comes the mode of display gray scale grade by this combination of a little.At this, each son field has the weight (hereinafter referred to as " gray shade scale weight ") of the gray shade scale of expression reflection.

Fig. 3 is the son figure that constitutes in 1 of plasma display system of expression embodiment of the present invention 1.In embodiment 1, with 1 field interval be divided into 8 the son (SF1, SF2 ..., SF8), each son field has the gray shade scale weight of (1,2,4,8,16,32,64,128).By making this a little field make up in every way and discharge, thereby show that " 0 " arrive the gray-level value of 256 grades of " 255 ".For example, gray-level value " 7 " is to show by SF1, SF2, SF3 with gray

shade scale weight

1,2,4 are discharged, and gray-level value " 21 " is by SF1, SF3, SF5 discharge with gray

shade scale weight

1,4,16 are shown.

Each son by: carry out T1 during the initialization of initialization discharge, the discharge cell that should discharge is write T2 during the writing of discharge and makes by T3 during writing keeping that discharge cell that discharge is written into discharges simultaneously constitute.

Fig. 4 is the figure of drive waveforms of the PDP1 of expression embodiment of the present invention 1.During the initialization of son in the T1, apply ramp voltage (ramp voltage) to scan electrode SCN1～SCNn, all carrying out the initialization discharge together in the discharge cell, to the historical record (history) of the wall electric charge of each discharge cell, form the required wall electric charge of next write activity simultaneously before eliminating.During writing, in the T2, apply scanning impulse successively, and apply the write pulse corresponding with the image signal that should show to data electrode D1～Dm to scan electrode SCN1～SCNn.Then, between scan electrode SCN1～SCNn and data electrode D1～Dm, cause selectively to write discharge, only form the wall electric charge at the discharge cell that is written into discharge.And then, during keeping in the T3, at scan electrode SCN1～SCNn and keep the pulse of keeping that applies between electrode SUS1～SUSn with the proportional number of times of gray shade scale weight, only make during writing T2 carry out the discharge cell that the wall electric charge forms and keep discharge.Also carry out same action for other son fields.

Then, the discharge current to PDP1 describes.Initialization discharge during the initialization in the T1 is based on the very weak discharge of ramp voltage as shown in Figure 4, and its discharge current is compared few with the discharge current of keeping discharge.Have again, write discharge owing to during writing, produce successively by each scan electrode in the T2, thus keep to discharge and compare with whole image is discharged, few based on the discharge current that writes discharge.Thus, the discharge current of PDP1 is lacking during the initialization and during writing, and can be determined substantially by the discharge kept during keeping.And the discharge current of keeping discharge is the summation of the discharge current of each discharge cell, therefore with keep during the ratio (hereinafter referred to as " lighting rate ") of discharge cell of discharge proportional.

Fig. 5 A～Fig. 5 D is the figure that changes the time of the rate of lighting of each the son field in representing 1.The rate of lighting when Fig. 5 A represents to have shown gray-level value " 255 " in whole discharge cells of PDP1.At this moment and since during the keeping of each son all discharge cells discharge, so all the rate of lighting of son fields is 100%.Fig. 5 B is illustrated in display gray scale grade point " 255 " in half discharge cell, the rate of lighting in remaining half during display gray scale grade point " 0 ".Under this situation, half remaining discharge cell does not all discharge, and the discharge cell of half remaining picture is in the interval discharge of keeping of each son field, and therefore the rate of lighting of 1 field interval all is 50% in each son field.The rate of lighting when Fig. 5 C is illustrated in display gray scale grade point " 127 " in whole discharge cells of PDP1.At this moment, (make whole discharge cells discharges among the SF1～SF7), the son SF8 with gray shade scale weight 128 does not discharge whole discharge cells to have 7 of gray

shade scale weight

1,2,4,8,16,32,64 sons.Thus, SF1 is 100 to the rate of lighting of SF7, and the rate of lighting of SF8 is 0%.The rate of lighting when Fig. 5 D represents to show general the reflection.At this moment, according to the gray-level value of reflection, the rate of lighting of each son field is got various values.But the rate of lighting of each son is constant in during the keeping of this child field.Like this, each the son keep during in the rate of lighting can according to the discharge the discharge cell number calculate.As mentioned above, if know the rate of lighting, the discharge current in during then measurable the keeping.

Then, the mechanism that is used to supply with discharge current is described.

Fig. 6 is the circuit diagram of power feeding section that is used to supply with discharge current of the plasma display system of embodiment of the present invention 1.In embodiment 1, as the electric power feed mechanism, employing can be by the DC-DC converter 140 of first current controling signal Cont control electric power supply capacity.

In Fig. 6, the constant triangle wave voltage Trw of 142 generation cycles of triangular wave generator and DC biasing (offset).Comparer 144 is voltage and the triangle wave voltage Trw of the first current controling signal Cont relatively, and PWM (PULSE WIDTH MODULATION) signal Cmp is produced.That is, comparer 144 is higher than output " H " signal under the situation of triangle wave voltage Trw, output " L " signal under low situation at the voltage of the first current controling signal Cont.By alternately repeating these " H " signals and " L " signal, thereby can produce pwm signal Cmp.Therefore,, then can increase the dutycycle of pwm signal Cmp if increase the voltage of the first current controling signal Cont, opposite if will reduce by the voltage of the first current controling signal Cont, then can reduce dutycycle.

This pwm signal Cmp is imported into the base stage of switch with transistor T 1, the primary side electric current I 1 of gauge tap transformer (switching transformer) 146.When pwm signal Cmp is " H " signal, flow through primary side electric current I 1, for " L " signal the time, be cut off.Thus, the dutycycle of pwm signal Cmp is big more, and the primary side electric current I 1 that time per unit flows through is just many more, and the secondary side current I2 that produces via switch transformer 146 also increases pro rata with primary side electric current I 1.Secondary side current I2 supplies to the pulse voltage of keeping described later after by rectification and applies circuit 172,182 in rectification circuit 148.Like this, control the electric power supply capacity of DC-DC converter 140 by the first current controling signal Cont.

Fig. 7 A is the light rate of expression when the first current controling signal Cont is made as parameter and the family curve of the relation of the output current Io of DC-DC converter 140 and output voltage V o, and transverse axis is represented output current Io and light rate that the longitudinal axis is represented output voltage V o.

In DC-DC converter 140, if the first current controling signal Cont is made as Vc1 (V), Io is made as I with output current ₀₁(A), then output voltage V o is V ₀₁(V).Under the state that the first current controling signal Cont is remained on Vc1 if output current Io to I ₀₂(A) increase, then output voltage can be from voltage V ₀₁(V) to voltage V ₀₂(V) reduce.But, if know that output current Io is from I in advance ₀₁(A) to I ₀₂(A) increase, then the variation with output current Io is elevated to Vc2 (V) with the first current controling signal Cont from voltage Vc1 (V) simultaneously, can make output voltage V o remain on V ₀₁(V) constant.Like this, if control the first current controling signal Cont, then the output voltage V o of DC-DC converter 140 can be kept constant according to the variation of output current Io.

At this, if remove the electric power of driving circuit internal consumption, then output current Io equates with discharge current, discharge current is arranged as mentioned above again and light rate proportional.Therefore, light the variation of rate by basis and control the first current controling signal Cont, thereby the output voltage V o of DC-DC converter 140 can be kept constant.

Fig. 7 B is the figure of relation that the rate and the first current controling signal Cont are lighted in expression, based on Fig. 7 A, the voltage table of the first current controling signal Cont is shown the longitudinal axis.As mentioned above, owing to can calculate the rate of lighting of image signal in advance, so if the relation of Fig. 7 B is stored in the storage part, then, then can make output voltage V o constant by corresponding with the rate of lighting and the first current controling signal Cont is input to DC-DC converter 140.

Like this, in first embodiment of the present invention, adopt and try to achieve the rate of lighting in advance, predict discharge current and make output voltage V o keep constant feedforward control.In feedforward control, because output voltage V o does not depend on current discharge current, so the control of can going ahead of the rest.

In addition, these family curves be from DC-DC converter 140 reality to plasma display system supply capability of the present invention, as parameter, the relation that rate and output voltage V o are lighted in actual measurement obtains with the first current controling signal Cont.Have again, by this feedforward control, with the electric current I c2 that flows into rectification circuit 148 almost the electric current of equivalent flow out simultaneously as output current Io, therefore can reduce the electric capacity of the capacitor that uses in the rectification circuit 148.

Then, the circuit of article on plasma display device formation describes.

Fig. 8 is the circuit block diagram of the plasma display system 100 of embodiment of the present invention 1.In AD translation circuit 102, the image signal Sig that is imported is carried out digital conversion, in sub-field transformation circuit 104, carry out sub-field transformation then, become 8 digital sub-field signal Sbi (i=1～8).And, through a son treatment circuit 106 and data electrode driver circuit 108, display map on PDP1.Have again, according to the sub-field signal Sbi of numeral, calculate the rate of the lighting Li of each son field, generate and light rate signal Ls as the rate of the lighting counting circuit 120 of lighting the rate calculating part.

At this, digital sub-field signal Sbi is the signal that makes the discharge of each discharge cell or do not discharge in being illustrated in during the keeping of i son.In embodiment of the present invention 1, the 1st digital sub-field signal Sb1 keeps the value of " 1 " for the discharge cell of discharge in during the keeping of the 1st son (SF1), at the value of the discharge cell maintenance " 0 " of not discharging.Same for the sub-field signal Sb2～Sb8 of numeral.Thus, light rate counting circuit 120 and calculate the sum of each digital sub-field signal Sbi " 1 ", carry out division arithmetic, try to achieve and light rate Li with whole discharge cell numbers, by with synchronously output during the keeping of these values and each, light rate signal Ls thereby generate.

Storer 130 will be used to make the output voltage V o of DC-DC converter 140 to keep the constant rate of lighting L and the relation of the first current controling signal Cont to store as look-up table (being designated hereinafter simply as " LUT ").Microcomputer 160 is read the first current controling signal Cont according to lighting rate signal Ls, and this control signal Cont is outputed to DC-DC converter 140 with reference to the LUT of storer 130.DC-DC converter 140 is according to the first current controling signal Cont, and the pulse voltage of keeping from the pulse voltage applying unit to the conduct of being located at scan electrode driving circuit 170 and keeping electrode drive circuit 180 that keep applies circuit 172,182 supply capabilities.Keep pulse voltage and apply circuit 172,182 to scan electrode SCN1～SCNn with keep electrode SUS1～SUSn and apply the pulse voltage of keeping that equates with output voltage V o.

In addition, power circuit 190 is converted to DC voltage with the alternating voltage of source power supply, to DC-DC converter 140 supply capabilities.Have again, apply circuit 172, the 182 required electric power of each circuit block supply in addition to keeping pulse voltage from not shown power circuit.And then timing control circuit 192 generates required timing controling signal according to synchronizing signal, and offers each block.

Then, the action of article on plasma display device describes.Fig. 9 A～Fig. 9 F is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 1.In embodiment 1, illustrate: the reflection that is presented on the PDP1 only postpones the situation that 1 field interval shows with respect to the image signal Sig of previous field.

Fig. 9 A represents to be input to the image signal Sig of plasma display system.Fig. 9 B represents the discharge current Id of the PDP1 corresponding with image signal Sig.Discharge current Id is corresponding to previous image signal Sig, and the size of the discharge current Id in during the keeping of the 1st son is made as D1.For D2～D8 too.

Fig. 9 C represents from the sub-field signal Sbi of 8 numerals of sub-field transformation circuit 106 outputs.As mentioned above, by the summation of the sub-field signal Sbi of numeral " 1 " being carried out division arithmetic with whole discharge cell numbers, thus the rate of the lighting Li in can obtaining during the keeping of i son.Fig. 9 D represents from the rate of the lighting signal Ls of the sub-field signal Sbi output of numeral.Light rate signal Ls and light rate " 0 " in output during the initialization of the 1st son and during writing, rate L1 is lighted in output during keeping.Equally, light rate " 0 " in output during the initialization of No. 2 later son and during writing, rate L2～L8 is lighted in output during keeping.Fig. 9 E represents the output current Io of DC-DC converter 140.

At this,, can know its value and discharge in advance regularly according to the discharge current Di that lights rate Li prediction PDP1.Thus, the value of the output current Io of DC-DC converter 140 for " 0 ", is adjusted in during keeping and lights the discharge current Di that rate Li dopes with basis and equate during initialization of each son and in during writing.That is, in Fig. 9 B, Fig. 9 E, the output current I1 during the keeping of the 1st son is for the value identical with the discharge current D1 of PDP1, also becomes the value identical with discharge current D2～D8 for the output current I2～I8 of No. 2 later son.Have again, output current I1～I8 only each the son keep during output, these timing is synchronous with the timing that each discharge current D1～D8 produces during keeping.Thus, shown in Fig. 9 F, the output voltage V o of DC-DC converter 140 can be kept constant.

In addition, in embodiment 1, illustrated with respect to the image signal Sig that is imported, discharge current Id postpones 1 field interval and situation about producing, but be under 2 the situation at this timing period, light rate signal Ls and also postpone 2 amount by making, thereby can be suitable for the present invention.Postponing with respect to image signal Sig to produce more than 3 under the situation of discharge too.

As mentioned above, calculate the rate of the lighting Li of each son field in advance, light rate Li, the output voltage V o of DC-DC converter can be controlled to be constant according to this.

(embodiment 2)

Figure 10 is the circuit diagram of power feeding section that is used to supply with discharge current of the plasma display system of embodiment of the present invention 2.In this embodiment 2, as the electric power feed mechanism, employing can be according to the DC-DC converter 141 of the first current controling signal Cont and second current controling signal Vadj control electric power quantity delivered.

In Figure 10, triangular wave generator 142 produces the triangle wave voltage of constant period, and the triangle wave voltage of generation becomes the triangle wave voltage Trw that has been set biasing in bias control circuit 143, and is imported into comparer 144.The bias of triangle wave voltage Trw is decided by the second current controling signal Vadj.And voltage and the triangle wave voltage Trw of 144 couples first current controling signal Cont of comparer compare, output PWM (PULSE WIDTH MODULATION) signal Cmp.

Under the situation of the voltage constant of Vadj, the cycle of triangle wave voltage Trw and biasing are all constant, and the dutycycle of the pwm signal Cmp that produces from comparer 144 only depends on the first current controling signal Cont.This state is equivalent to the operating state of the DC-DC converter 140 that is used for plasma display system in the embodiment of the present invention shown in Figure 61.That is, with respect to the rapid variation of the discharge current of PDP, by feedforward control, the output voltage V o that may be controlled to DC-DC converter 140 is constant.

But, the unpredictable variations such as change that produce source power supply in fact sometimes, output voltage V o change.In addition, as the main cause of output voltage V o change, consider the difference of the use part of plasma display system.Because use the difference of part, output current Io and the actual discharge electric current of only setting by feedforward control is inconsistent sometimes.Taking into full account in the product manufacturing on the basis of difference of part, must carry out the volume production design, the influence that difference caused that therefore reduces this part is important.

In the plasma display system of embodiment of the present invention 2, further by the FEEDBACK CONTROL second current controling signal Vadj, thereby replenish above-mentioned feedforward control, suppress the change of output voltage V o.

Below, the action of the second current controling signal Vadj is described.The second current controling signal Vadj is by relatively the value of the output voltage V o of DC-DC converter 141 and the value of reference voltage generate.The value of so-called reference voltage is meant the desired value of output voltage V o.

Figure 11 A and Figure 11 B are the figure of the relation of the expression second current controling signal Vadj and triangle wave voltage Trw and pwm signal Cmp.In Figure 11 A, the expression output voltage V o situation higher than reference voltage.At this moment, the magnitude of voltage of the second current controling signal Vadj rises, in the biasing increase of bias control circuit 143 intermediate cam wave voltage Trw.Thus, the dutycycle of pwm signal Cmp reduces, and the output current Io of DC-DC converter 141 reduces, so output voltage V o reduction, approaches reference voltage.Have, Figure 11 B is the situation that output voltage V o is lower than reference voltage again, and the magnitude of voltage of the second current controling signal Vadj descends, and the biasing of triangle wave voltage Trw reduces.Therefore, the dutycycle of pwm signal Cmp increases, and the output current Io of DC-DC converter 141 increases, so output voltage V o increase, near reference voltage.

Like this, the plasma display system of embodiment of the present invention 2 even there is the change that can't expect of generations such as source power supply, also can suppress the change of output voltage V o by FEEDBACK CONTROL, returns to reference voltage.Have again,, also can detect the change of the output voltage V o that produces by this difference, come FEEDBACK CONTROL output current Io by the second current controling signal Vadj even the use part of plasma display system there are differences.Thus, even also can suppress the change of unpredictable output voltage V o in this case.

In addition, in Figure 11 A and Figure 11 B,, also can constitute the biasing of first current controling signal Cont control triangular wave, can also constitute the biasing of two control signal control triangular waves though the second current controling signal Vadj has controlled the biasing of triangular wave.Also have, can't be directly for the high value and reference voltage when comparing at output voltage V o, can will compare after the output voltage V o dividing potential drop.

Then, the circuit of article on plasma display device formation describes.The circuit block diagram of the plasma display system 101 of embodiment of the present invention 2 during Figure 12.

Different with the plasma display system 100 of embodiment of the present invention 1 is: import feedback voltage control circuit 150, not only by the first current controling signal Cont, also control DC-DC converter 141 by the second current controling signal Vadj.

Feedback voltage control circuit 150 usefulness comparers 154 detect the difference of output voltage V o with the reference voltage V ref that exports from reference voltage generating circuit 152 of current DC-DC converter 141.And, generate the second current controling signal Vadj according to this difference, and output to DC-DC converter 141.Output voltage V o with keep pulse voltage and equate, control the output current Io of DC-DC converter 141 according to keeping pulse voltage.

DC-DC converter 141 is according to the first current controling signal Cont and the second current controling signal Vadj, applies circuit 172,182 supply capabilities to the pulse voltage of keeping of being located at scan electrode driving circuit 170 and keeping electrode drive circuit 180.Keep pulse voltage and apply circuit 172,182 to scan electrode SCN1～SCNn with keep electrode SUS1～SUSn and apply the pulse voltage of keeping that equates with output voltage V o.

Then, the action of article on plasma display device describes.Figure 13 A～Figure 13 F is the figure of output signal of each circuit block of the plasma display system of expression embodiment of the present invention 2.Same with above-mentioned embodiment 1, illustrate: be presented at reflection on the PDP1 and only postpone 1 field interval with respect to the image signal Sig of previous field and show.

Figure 13 A represents to be input to the image signal Sig of plasma display system.Figure 13 B represents the discharge current Id of the PDP1 relative with image signal Sig.Discharge current Id is corresponding to previous image signal Sig, and the size of the discharge current Id in the T3 during the keeping of the 1st son is expressed as D1.For D2～D8 too.Figure 13 C represents from the sub-field signal Sbi of 8 numerals of sub-field transformation circuit 104 outputs.As mentioned above, by the summation of the sub-field signal Sbi of numeral " 1 " being carried out division arithmetic, thereby can obtain the rate of the lighting Li in the T3 during the keeping of i son with whole discharge cell numbers.Figure 13 D represents from the rate of the lighting signal Ls of the sub-field signal Sbi output of numeral.Light rate signal Ls at T1 during the initialization of the 1st son and during writing T2 output light rate " 0 ", rate L1 is lighted in T3 output during keeping.Equally, rate " 0 " is lighted in T2 output at T1 during the initialization of No. 2 later son and during writing, and rate L2～L8 is lighted in T3 output during keeping.Figure 13 E represents the output current Io of DC-DC converter 140, and Figure 13 F represents this output voltage V o.

At this,, can know its value and discharge in advance regularly according to the discharge current Di that lights rate Li prediction PDP1.Thus, the value of the output current Io of DC-DC converter 140 during initialization of each son T1 and write during be " 0 " in the T2, during keeping, be adjusted in the T3 and light the discharge current Di that rate Li dopes with basis and equate.That is, in Figure 13 B, Figure 13 E, the output current I1 of T3 also becomes the value identical with discharge current D2～D8 for the value identical with the discharge current D1 of PDP1 during the keeping of the 1st son for the output current I2～I8 of No. 2 later son.Have, output current I1～I8 is T3 output during the keeping of each son only again, and these are regularly synchronous with each discharge current D1～D8 timing that T3 produces during keeping.By such feedforward control, shown in Figure 13 F, the output voltage V o of DC-DC converter 140 can be kept constant.

Figure 14 A～Figure 14 D is the figure that changes the time of expression primary side electric current I c1 with the relation of the output current Io of the second current controling signal Vadj and DC-DC converter 141 and output voltage V o.

Figure 14 A represents that the time of primary side electric current I c1 changes.In Figure 14 A, the moderate change that dots is exactly the variation from the primary side electric current I c1 of power circuit 190 supplies.For example source power supply change, irregular cycle of primary side electric current I c1, with keep corresponding to each of son during the discharge current that produces of T3 and the cycle of output current Io jumpy compare very longly, be the cycle that can fully follow the trail of by FEEDBACK CONTROL.In addition, for convenience of description, the period ratio actual cycle of illustrated primary side electric current I c1 is short.Have again, each son field (SF1, SF2 ..., SF8) keep during the fierceness of primary side electric current I c1 in the T3 change expression and be used to generate the conducting of primary side electric current I c1 of output current Io and the repetition of cut-out.

Figure 14 B represents the second current controling signal Vadj that changes corresponding to primary side electric current I c1.The change long with respect to the cycle of primary side electric current I c1, the second current controling signal Vadj is to the directive effect of eliminating described change.

Shown in Figure 11 A, under the situation that primary side electric current I c1 increases, output current Io increases, and output voltage V o raises.Feedback voltage control circuit 150 detects the fact that this output voltage V o raises, and the voltage of the second current controling signal Vadj is risen, so the dutycycle of DC-DC converter 141 reduces.Consequently, can suppress the increase of output current Io, output voltage V o is kept constant.Have, shown in Figure 11 B, under the situation that primary side electric current I c1 reduces, output current Io reduces again, and output voltage V o reduces.Feedback voltage control circuit 1 50 detects the fact that output voltage V o reduces, and the voltage of the second current controling signal Vadj is descended, so dutycycle increases.Thus, can suppress the minimizing of output current Io specifically, output voltage V o is kept constant.Figure 14 C and Figure 14 D represent the output current Io and the output voltage V o of DC-DC converter 141.

In addition, in embodiment 1, illustrated with respect to the image signal Sig that is imported, the situation that makes discharge current Id postpone 1 field interval and produce, but be under 2 the situation at this timing period, light rate signal Ls and also postpone 2 amount by making, thereby can be suitable for the present invention.Even postponing with respect to image signal Sig to produce more than 3 under the situation of discharge too.

As mentioned above, calculate the rate of lighting Li of each son in advance, light rate Li according to this, export with keep during the output current Io of the DC-DC converter that equates of the discharge current Id of T3, be constant with voltage Vo feedforward control.Have, the change at unpredictable source power supply etc. can suppress the change of output voltage V o by FEEDBACK CONTROL again.

In addition, in the extremely many high-fineness PDP of discharge cell, PDP is split into a plurality of scanning blocks, supplies with a lot of electric power when keeping of each scanning block discharged.Import among this high-fineness PDP by the plasma display system that will the present invention relates to, keep the required electric power of discharge thereby can supply with, and foot phenomenon not often not.Thus, can obtain the PDP of aniconia inequality, clear display image.

(industrial utilizability)

Even owing in the discharge current of PDP situation jumpy, also can provide a kind of will failing Go out voltage keep constant, with the plasma display system of correct gray-level value display map, so this The plasma display system of invention is useful as large-scale picture display device etc.

Claims

1. plasma display system, wherein 1 field interval by during having an initialization, write during and keep during a plurality of sons constitute, Plasmia indicating panel comprises a plurality of discharge cells that have scan electrode, keep electrode and data electrode, by described discharge cell is discharged during described keeping or do not discharge and on described Plasmia indicating panel display map

This plasma display device comprises:

Keep the pulse voltage applying unit, it applies the pulse voltage of keeping that makes described a plurality of discharge cell discharge usefulness to described scan electrode and the described electrode of keeping;

Light the rate calculating part, the rate of lighting of the discharge ratio of the described a plurality of discharge cells in it calculates during described the keeping of expression by described image signal with regard to each son field in advance;

Power feeding section, it is to the described pulse voltage applying unit supply capability of keeping; With

Control part, it controls described power feeding section according to the described rate of lighting, so that described to keep pulse voltage constant.

2. plasma display system according to claim 1 is characterized in that,

Described control part has feedforward control portion, and it is asked for first current controling signal and be input to described power feeding section according to the described rate of lighting,

By controlling the output current of described power feeding section according to described first current controling signal, thereby the output voltage of described power feeding section is kept constant.

3. plasma display system according to claim 2 is characterized in that,

Described control part also comprises FEEDBACK CONTROL portion, and it is asked for second current controling signal and be input to described power feeding section according to the output voltage of described power feeding section,

By controlling the output current of described power feeding section according to described first current controling signal and described second current controling signal, thereby the output voltage of described power feeding section is kept constant.

4. according to each described plasma display system in claim 2 or 3, it is characterized in that,

Described feedforward control portion has and will light the storage part that corresponding described first current controling signal of rate is stored in advance with described.