CN101118722B

CN101118722B - Plasma display apparatus

Info

Publication number: CN101118722B
Application number: CN2007100059541A
Authority: CN
Inventors: 竹内正宪; 上田寿男; 浅生重晴
Original assignee: Hitachi Plasma Display Ltd
Current assignee: Hitachi Consumer Electronics Co Ltd
Priority date: 2002-03-12
Filing date: 2002-12-06
Publication date: 2010-10-06
Anticipated expiration: 2022-12-06
Also published as: JP5097076B2; CN101118722A; JP2009064027A

Abstract

A PDP apparatus in which degradation in image quality such as display missing points does not occur, even if the peak luminance is increased, has been disclosed. In the PDP apparatus, the display load ratio of each subfield is detected and a sustain pulse cycle is changed according to the display load ratio of each subfield. Moreover, an adaptive sustain pulse number change means is provided, which calculates the total amount of variations in time by summing the variations in time in a display field caused by the changes in the sustain pulse cycles and increases/decreases the number of sustain pulses of each subfield according to the total amount of variations in time.

Description

Plasm display device

It is 02154574.X that the application of this division is based on application number, and the applying date is on Dec 06th, 2002, and denomination of invention is divided an application for the Chinese patent application of " plasm display device ".

Technical field

The present invention relates to the sub-field method of a kind of usefulness and provide the plasm display device that gray shade scale shows.

Background technology

Plasm display device (PDP device) has dropped into practical application as a kind of flat-panel screens, and it is a kind of thin display with high brightness.In the PDP device, because only may control each display unit or lighted or do not lighted, thereby display field is made into by a plurality of sons and forms, and joins together with the demonstration that provides gray shade scale is arranged in each display unit in the son field of being lighted.Each height field comprises an access time interval at least, selected and retention time interval of display unit in this time interval, and in this time interval, the unit of choosing is lighted.In this retention time interval, add that one keeps pulse so that discharge takes place once to keep, and brightness is by the number decision that keeps pulse.Consequently, be identical if keep the cycle of pulse, brightness is just by retention time length of an interval degree decision so.Though the most general and effective structure of son field is a kind of like this structure, in this structure interval order of the retention time of each height field increase and in a son in retention time burst length and the last height field ratio of retention time burst length be 2, but each seed field structure has been proposed recently to suppress false contouring.The present invention can be applied to any PDP device of showing with arbitrary sub-field structure.

In addition, proposed the whole bag of tricks for the PDP device, the present invention can be applied to use the PDP device of any method.Because the structure of PDP device and driving method be likewise known, omit its detailed description herein.

In the PDP device, when all the ratio (demonstration loading ratio) of unit is big in the unit that will be lighted and the whole screen, has a big holding current and flow through, owing to the effective voltage that keeps pulse can descend brightness is diminished.When realizing having the demonstration of gray shade scale with the son field, such problem can appear, promptly owing to show that to another height field the brightness ratio of loading ratio difference and each height field departs from a given relation, thereby the demonstration of gray shade scale can not be arranged normally from a son.In order to address this problem, Japanese unexamined patent open (kokai) N0.9-185343 has announced such structure, therein, by detecting the demonstration loading ratio of each height field, keeps the number of pulse to proofread and correct to keep brightness ratio to each height field.

One of problem relevant with the PDP device is the peak brightness that its peak brightness will be lower than CRT, and power consumption is big.Thereby power control is carried out in this manner, when the brightness of whole elephant when being high, in each height field, keep the number of pulse to show that has resembling than low-light level on the whole by minimizing, and when the brightness of whole elephant when being low, by be increased in keep pulse in each height field number to show that has resembling of higher brightness on the whole.As a kind of method of power controlling, Japanese unexamined patent open (kokai) N0.2000-322025 has announced such method, wherein by detecting the mean flow rate grade of whole screen, keeps the recurrence interval when brightness degree just shortens less than a certain set-point.In this way, be under the dark situation on the whole when resembling, can improve peak brightness.

When shorten keeping the recurrence interval, keep the influence of pulse waveform distortion to become bigger, and the sustaining voltage that appointment may take place can add.Especially when showing that loading ratio is big, holding current increases, and the actual effective voltage that adds descends according to the voltage landing.Fig. 1 is that expression is 6 μ s for keeping pulse when add the pulse of given voltage, 8 μ s, and 10 μ s show the relation between effective sustaining voltage under loading ratio and this demonstration loading ratio.If effective voltage descends, such problem can appear, promptly can not cause to keep discharge, or discharge termination midway, thereby cause the generation of losing a little, perhaps say the light emission that can not realize obtaining normal brightness.In the structure that open (kokai) N0.2000-322025 of Japanese unexamined patent announces, when brightness degree hour, also promptly show loading ratio hour, keeping the recurrence interval to shorten, thereby realize among Fig. 1 breaking the represented control of broken line A with short.

Yet when the method with the son field realized representing of gray shade scale, real problem was the problem of the demonstration loading ratio in each height field.For example, in the son that has a big brightness ratio at, show that loading ratio is very little, and when in a son with little brightness ratio, showing that loading ratio is big, promptly the mean flow rate grade (demonstration loading ratio) with whole screen diminishes, and so just need shorten according to open (kokai) NO.2000-322025 of Japanese unexamined patent to keep the recurrence interval.Consequently,, keep the recurrence interval also to be shortened, at this moment will go out phenomenon and produce a little such problem of losing even have big demonstration loading ratio but have in the son of little brightness ratio.

Summary of the invention

The objective of the invention is to realize a kind of like this PDP device, wherein can not cause low-quality elephant the as display dot is lost in generation, even increase peak brightness.

To achieve these goals, in PDP device of the present invention, detected each demonstration loading ratio of sub and, changed the maintenance recurrence interval according to each demonstration loading ratio of sub.If yet the retention time interval of each height field fix, when maintenance recurrence interval of parton field changes, will cause the change of brightness ratio so.Thereby in the present invention, provide a kind of self-adaptation to keep the pulse number modifier to increase/reduces maintenance pulse number in each height field with total variation according to the time, and the total variation of time be in a display field owing to keep the variation of recurrence interval to cause that each time variation is sued for peace obtaining.

Fig. 2 is a sketch of the explanation principle of the invention.As shown in the figure, a display field is made up of to SF4 four son SF1.Keeping before the recurrence interval changes, the maintenance recurrence interval of each height field is 8 μ s, and SF1 is 80 μ s to the retention time interval of SF4,160 μ s, and 320 μ s and 640 μ s, and SF1 is 10,20,40 and 80 to the maintenance pulse number of SF4.

When the demonstration loading ratio of SF3 and SF4 less than a set-point, their maintenance recurrence interval is changed into 6 μ s, in the case, if dutycycle is fixed, pulse width will change with same ratio.If the maintenance pulse number of SF3 and SF4 remains on 40 and 80, so consequently in SF3 and SF4, produced the unoccupied time of 80 μ s and 160 μ s respectively.Then, the maintenance recurrence interval of SF1 and SF2 is maintained 8 μ s, the maintenance recurrence interval of SF3 and SF4 maintains 6 μ s, and SF1 is adjusted to 12,24,48,96 respectively to the maintenance pulse number of SF4, by this way, the sum that keeps pulse is increased to 180 from 150, thereby has improved peak brightness, and the brightness ratio of each height field has kept given relation.To keep the number of pulse in each height field and the brightness ratio of each son field is remained unchanged in order to be increased in again, need 96 μ s or longer unoccupied time, but 48 μ s shown in the figure and unoccupied time are less than the required time, thereby 48 μ s just remain as unoccupied time.Show that SF1 that loading ratio is big and the maintenance recurrence interval of SF2 still are 8 μ s, this just causes can not producing losing a little, though and the maintenance recurrence interval of SF3 and SF4 become 6 μ s because low demonstration loading ratio can not produce too and lose a little.

On the contrary, when showing loading ratio, also can make the maintenance discharge stability by the maintenance recurrence interval of expanding the son field greater than set-point.Particularly in the PDP device, to control and when the exomonental sum of light increases power consumption and becomes too big power consumption usually, reduce and keep the pulse sum.Thereby in the case, in each frame, to produce a unoccupied time as its result.Thereby, in this case, keep the recurrence interval so that the maintenance discharge stability is suitable by expansion.If thereby show that loading ratio is lower than set-point, then keep the recurrence interval modifier to shorten the maintenance recurrence interval of each height field, when greater than set-point, then expand the maintenance recurrence interval.Though can all be processed into all sons field the object of frequency correction, also can a handling part molecule field, comprising the son with high-high brightness, as the object of frequency correction.

Self-adaptation keeps the increase/minimizing of pulse number modifier to keep pulse number constant with the brightness ratio that keeps each son field.

In addition, as shown in Figure 1, because as change keeps the recurrence interval, effectively sustaining voltage and brightness will change, thereby an additional adaption brightness means for correcting is provided is more suitable, proofread and correct the brightness that causes owing to the variation that keeps the recurrence interval with it and change, and self-adaptation keeps the pulse number modifier according to the result who proofreaies and correct, each maintenance pulse number of sub of increase/minimizing.

In addition, effectively sustaining voltage depends on demonstration loading ratio of each son and changes, thereby correspondingly to correct this change be suitable, and self-adaptation keeps maintenance pulse number of each sub-field of pulse number modifier increases/minimizings.

When keeping the recurrence interval to be changed, if there is bigger variation in the cycle, can cause the variation that demonstration is big, thereby, carry out variation length by length, so that such variation is not perceiveed preferably through a plurality of demonstrations field.In addition, when changing the maintenance pulse, preferably carry out variation length by length through a plurality of demonstrations field according to the variation that keeps the recurrence interval.

When demonstration loading ratios of all son fields or those son fields with given brightness or higher brightness are lower than a certain set-point, make mutually and equate that control will be easier so if maintenance recurrence intervals or comprise of all sons have the maintenance recurrence interval of the parton field of that son of high-high brightness.

Description of drawings

To more be expressly understood the features and advantages of the present invention from narration below in conjunction with accompanying drawing, wherein:

Fig. 1 illustrated for the different maintenance recurrence intervals, showed loading ratio and the sketch that effectively concerns between the sustaining voltage.

Fig. 2 is the sketch of the explanation principle of the invention.

Fig. 3 is a block diagram that provides PDP device rough structure in first embodiment of the present invention.

Fig. 4 is a sketch of the process of explanation in first embodiment.

Fig. 5 is a process flow diagram that is given in the process in first embodiment.

Fig. 6 is a process flow diagram that is given in the process in first embodiment.

Fig. 7 is a process flow diagram that is given in the process in first embodiment.

Fig. 8 is a block diagram that provides PDP device rough structure in second embodiment of the present invention.

Fig. 9 is a block diagram that provides PDP device rough structure in the 3rd embodiment of the present invention.

Figure 10 is a process flow diagram that is given in the 4th process in the embodiment.

Figure 11 is a process flow diagram that is given in the 4th process in the embodiment.

Figure 12 is a process flow diagram that is given in the 4th process in the embodiment.

Figure 13 is a process flow diagram that is given in the 4th process in the embodiment.

Figure 14 is a process flow diagram that is given in the 4th process in the embodiment.

Figure 15 is when the process in the 4th embodiment of application, shows the sketch of an example of its result.

Embodiment

Fig. 3 is a block diagram, and it has shown the rough structure of PDP device in first embodiment of the present invention.As shown in the figure, this PDP device comprises a plasma display panel 11, an address electrode driving circuit 12, signal of its output is to drive the address electrode of flat board 11, a scan electrode driving circuit 13, be added to scan electrode (Y electrode) its output one scan pulse sequence, and output reset pulse and a maintenance of maintenance pulse electrode drive circuit 14, its output is added to (the X electrode) that keeps on the electrode, reset pulse and maintenance pulse, an A/D change-over circuit 21, it produces a timing signal and video input signals is changed into digital signal, a display gray scale is adjusted circuit 22, it adjusts the vision signal number of grayscale levels by resembling processing such as high dither and error diffusion, a vision signal-SF coincidence circuit 23, how it makes up the son lighted to realize the stratified demonstration to each display unit by launching adjusted video signal with decision, and SF treatment circuit 24, it is that a son demonstration produces a drive signal, and this drive signal is to output to address electrode driving circuit 12 from SF treatment circuit 24, scan electrode driving circuit 13, and keep electrode drive circuit 14.Because the structure of the conventional PDP device of said structure and prior art is the same, therefore just omit here about waveform with other or the like detailed description.

PDP device in first embodiment comprises a SF loading ratio testing circuit 25, it detects the demonstration loading ratio of each son field, a hold period changes circuit 26, it recently changes the maintenance recurrence interval of each son field according to each son detected demonstration load, a vacant time (vacant time) counting circuit 27, it calculates the variation of vacant time when keeping the recurrence interval to be changed, a vacant time is redistributed circuit 28, it redistributes the vacant time that calculates, this time is proportional to the brightness ratio of each son field and keeps the product of recurrence interval, with a display gray scale correcting circuit 29, it distributes the maintenance pulse for by this way each section period, through increasing pulse number in a plurality of fields or reducing pulse number, to keep the continuity of brightness through a plurality of fields.Vacant time calculation circuit 27 and vacant time are redistributed circuit 28 and keep the pulse number modifier corresponding to self-adaptation.

Fig. 4 is the sketch that concerns between each process in explanation vision signal and first embodiment.As shown in the figure, at the top of a display field vertical synchronizing signal VIN is arranged, it detects the beginning of each display field.After vertical synchronizing signal VIN, the vision signal input.After all videos signal input of each display field, in the vision signal input beginning of next display field, carry out process 1.Afterwards, synchronous with each sub beginning, implementation 2 by each height field is produced drive signal, is finished once demonstration.

Fig. 5 is the process flow diagram of process 1, and Fig. 6 is the process flow diagram that is presented at the process A that carries out in the process 1.

In step 101, measure the demonstration loading ratio SFL[i of each height field SF].In step 102, the demonstration loading ratio SFL[i of each height field] and the brightness ratio SFW[i of each height field] product by for the summation of all sons to calculate the weighted mean load.Process in step 101 and step 102 is finished by a SF loading ratio testing circuit 25.

In step 103, earlier whether judge the weighted mean load less than 25%, when being equal to or greater than 25%, flow process enters step 105, process is by normally carrying out, when it less than 25% the time, flow process enters step 104, implementation A.Process in step 103 and step 104 changes circuit 26 by a hold period and a unoccupied time counting circuit 27 is finished.Process A is narrated below with reference to Fig. 6.

In step 121, input expression 6 μ s keep the variable SUS6 of pulse number and the variable SUS8 that 8 μ s keep pulse number, give initial value 0 setting unoccupied time TIM initial, and initial value 1 is provided with on the sequence number n that gives the son field.In step 122, demonstration loading ratio SFL[n when the arbitrary height field that in step 101, measures] less than 25% the time, flow process enters step 123, and when it was equal to or greater than 25%, flow process entered step 126.

In

step

123,1, it represents 6 μ s, sends the SFT[n that expression keeps the recurrence interval to].In step 124, SUS6 has increased sub and has kept umber of pulse SFP[n] such numerical value.When keeping the recurrence interval when 8 μ s change over 6 μ s, produced SFP[n] * 2 μ s unoccupied times, thereby TIM has increased corresponding numerical value in step 125, then flow process enters step 128.

And in

step

126,0, it represents 8 μ s, sends the SFT[n that expression keeps the recurrence interval to].In step 127, SUS8 has increased sub and has kept umber of pulse SFP[n] such numerical value.Because do not produce unoccupied time in the case, flow process enters step 128.

In step 128, a son sequence number n increases by 1, and in step 129, judges whether all to have finished each step of from 122 to 128 for all son fields, if not, then flow process is returned step 122, if finished, flow process enters step 130.

In

step

130 and 131, keep unoccupied time pulse number SUS8 and 6 μ s to keep the ratio of pulse number SUS6 to be divided into two parts according to 8 μ s, obtain 8 μ s by the increment that calculates SUS8 and SUS6 and keep final number SUS8 of pulse and 6 μ s to keep the final number SUS6 of pulse.In step 132,, obtain total maintenance pulse number SUS by SUS8 and SUS6 addition.Then, flow process is returned step 105 among Fig. 5.

In step 105, the SUS that obtains in step 132 is confirmed as keeping the sum of pulse.In step 106, keep the sum of pulse to be assigned to each height field, thereby obtain the maintenance umber of pulse SFP[i of each height field], the process in step 106 is redistributed circuit 28 by unoccupied time and is finished.

In step 107, because according to showing that the voltage landing that loading ratio causes has caused brightness decline, corresponding value is corrected.Simultaneously, owing to keep the recurrence interval change to cause that the brightness that change the caused variation of effective voltage also is corrected.In step 108, when the number that keeps pulse is changed, adjusts like this and make this variation carry out length by length through a plurality of fields.For example, when the sum that keeps pulse when 150 are increased to 180, to change length by length by this way three sons, it keeps the sum of pulse to change into 160 in next, in second next, change into 170, in the 3rd next, change into 180.Process in step 107 and step 108 is finished by display gray scale grade correcting circuit 29.

In step 109, initial value 1 is sent to symbol m, son field of its expression will be shown, and process 1 has been finished.

Fig. 7 is the process flow diagram of expression process 2.

In step 151, judge that expression keeps the SFT[m of recurrence interval], be 1 if judge its value, it is corresponding to 6 μ s, and then flow process enters step 152, as judges that its value is 0, and it is for 8 μ s, and then flow process enters step 153.In step 152, keep the recurrence interval to be set to 6 μ s, and in step 153, it is set to 8 μ s.

In step 154, what in step 106, obtain, and the maintenance pulse number SFP[m of a son of in

step

107 and 108, having adjusted] read, and will with the maintenance pulse number be set to controlled parts.In step 155, m adds 1 to finish this process.

As mentioned above, finish to process 2 and each sub-field synchronization.

Though in first embodiment,, only used 8 μ s and two ranks of 6 μ s for keeping the recurrence interval, also may provide more rank so that, for example, normal rank is 8 μ s, when showing that loading ratio is low, it changes into 6 μ s, and when showing that loading ratio is high, changes over 10 μ s.

Though in first embodiment, keep the recurrence interval to change into 6 μ s from 8 μ s, and keep the pulse sum is to be adjusted to increase length by length, but also may change over 6 μ s to the maintenance recurrence interval from 8 μ s length by length through a plurality of fields by this way, as the maintenance recurrence interval in next is made into 7.5 μ s, make 7.0 μ s to second in next, make 6.5 μ s to the 3rd in next, make 6.0 μ s to the 4th in next.

In addition, though according to show loading ratio want change to as if maintenance recurrence intervals of all son fields, but also is the maintenance recurrence interval of such son field desirable as the object that will change, this brightness of a little is greater than a certain designated value, this a little field also comprises the son field with high-high brightness, because, can produce longer unoccupied time when in the high son field of brightness ratio, shortening maintenance during the recurrence interval.In this case, the increase of the maintenance umber of pulse that causes owing to unoccupied time can be re-assigned to all sons or such parton field, and brightness of this part son is greater than a certain designated value, and this part son field also contains the son with high-high brightness.By to changing the restriction of the object that keeps the recurrence interval, the amount of operation can reduce.

In addition, though the demonstration loading ratio of each height field is judged respectively, and when being judged as when low, after in each height field, keeping the recurrence interval and keeping pulse number to be calculated, calculate total maintenance pulse number, in the time of also may and finding each value, shorten maintenance recurrence intervals of all son fields at the demonstration loading ratio of at first judging all son fields all less than a certain set-point.In the case, just the maintenance pulse number of each son field being multiply by that all will be made changes the ratio that front and back keep the recurrence interval, thereby obtains being easy to operate.Equally in the case, if keep the recurrence interval to want the object of change to be limited in such one a little, this brightness ratio of a little contains the son field with high-high brightness greater than a certain set-point and this a little field, and operational ton just can further reduce so.

Fig. 8 is a block diagram that provides PDP device rough structure in second embodiment of the present invention.Relatively can be clear that it and Fig. 3 that the difference of the PDP device in it and first embodiment is to have added that here a planar surface temperature sensing circuit 31 and one keep pulse number that circuit 32 is set.By increase keeping the number of pulse, the temperature of dull and stereotyped 11 bright area rises, if become too big in a bright area and the temperature difference of not putting bright area, may cause the damage of flat board 11.For fear of this situation, in second embodiment, the rising of temperature is monitored by planar surface temperature sensing circuit 31, and the maintenance pulse number is provided with circuit 32 when detecting the temperature rising above a certain set-point, suppresses to keep the rising of the increase of pulse number with the minimizing temperature.

Fig. 9 is a block diagram that provides PDP device rough structure in the 3rd embodiment of the present invention.Relatively can be clear that it and Fig. 8 that the difference of the PDP device in it and second embodiment is to have added a still image testing circuit 33.Owing to the rising of plate temperature causes dull and stereotyped damage to be because some bright area and not put the temperature difference of bright area caused.Under the situation of motion video, because some bright area and non-some bright area are unfixing, thereby the unlikely temperature difference that the part takes place, and under the situation of still image, produce the temperature difference easily partly, thereby in the PDP device of the 3rd embodiment, when still image testing circuit 33 detected a still image, it was just notified and keeps pulse number that circuit 32 this situations are set.Keeping pulse number that circuit 32 is set is static and the planar surface temperature is the increase that will suppress to keep pulse number under the high situation at image.

In above-described first to the 3rd embodiment, having described by shortening keeps the recurrence interval to increase the example that keeps pulse number, but also can be such situation, when showing that loading ratio is big, by prolonging, rather than shorten that to keep the recurrence interval to obtain stable discharge more desirable.In described below the 4th embodiment, describe such example, wherein in a certain height field, kept the recurrence interval to be shortened; And in another height field, keep the recurrence interval to be extended.

PDP device in the 4th embodiment of the present invention and the PDP device in first embodiment as shown in Figure 3 have similar structure, wherein carry out same process as shown in Figure 4, but the content of process are different.

Figure 10 is a process flow diagram of process 1 in the 4th embodiment.

As shown in figure 10, in the process 1 of the 4th embodiment, up to step 102, its process is identical with first embodiment.Subsequent in step 201, from calculate the weighted mean load, and consider power consumption, temporarily determine total pulse number TSUSO that keeps.In step 202,, calculate the maintenance umber of pulse SEPO[i of each height field] according to the brightness ratio of son field from total maintenance pulse number TSUSO.

Then in step 203, carry out process B, the maintenance recurrence interval of each height field is changed in process B.Afterwards from the process of step 204 to 208 be identical from step 105 to 109 process in the first embodiment.

Figure 11 is the process flow diagram that is given in the process B that carries out in the process 1.In process B, n, the maintenance recurrence interval SET[i of each height field] and unoccupied time TIM all in step 211, be initialized as 0.In step 212, corresponding to each height field loading ratio SFL[n] each the son maintenance recurrence interval SFT[n] temporarily decide based on the table that in Figure 11, provides.This table is provided for hold period and changes circuit 26.After further completing

steps

213 and 214, said process is repeated in each height field.

In step 215, the T.T. STIMI in the retention time interval in a field is by the maintenance recurrence interval SFT[i of each height field that the front is determined] multiply by keep pulse number SFP[i] calculate.In step 216, judge whether STIMI surpasses the maximal value STIMO of interval T.T. of retention time in the field.If do not surpass, just may increase and keep the pulse sum, thereby just can be in step 217 implementation C, in process C, keep the sum of pulse to be increased, if surpass, implementation D in step 218, in process D, keep the pulse sum to be reduced, be necessary because reduce the sum of maintenance pulse.

In the table of mentioning in front, list according to impulsive load,, when loading ratio is big, keep the recurrence interval to be extended when a loading ratio hour hold period is shortened than the only maintenance recurrence interval.

Figure 12 is the process flow diagram of expression process C.In step 221, be sent among the vacant time T IM at the difference STM0-STM1 of STIM0 and foregoing STIM1.Then in step 222, unit of account time UNIT_T, it is by the brightness ratio of each height field being multiply by the maintenance recurrence interval SFT[i of each height field], and with first son SF[1] calculate as a reference, this UNIT_T will use when changing holding frequency.In step 223, unit of account keeps umber of pulse UNIT_N, and it is by the brightness ratio SFW[n of each son SF] divided by the brightness ratio SFW[1 of first son] and summation calculate, this UNET_N will use when changing holding frequency.

Being necessary recently increases the number that keeps pulse for each height field according to brightness, also be, for example, if at SF[1] in increase by one and keep pulse, so at SF[2] in just need to increase by two pulses to keep brightness ratio constant, thereby when at SF[1] in increase by one and keep pulse, constant in order to keep brightness ratio, in a whole frame, will increase maintenance umber of pulse UNIT_N.Also promptly, when keeping umber of pulse to change, UNIT_N is a units.In the case, also be necessary to make retention time increase UNIT_T in the whole frame.Also be that UNIT_T remains on a constant desired unit interval of the brightness ratio in the field increasing the maintenance umber of pulse.

In step 224, vacant time T IM is removed by UNIT_T, can have what UNIT_Ts thereby calculate.Also promptly, calculate the number of the UNIT_Ns that can increase.In the case, fractional part is by integer.Then, the result who calculates be multiply by the number of the UNIT_Ns that calculates to calculate the number SUS of the maintenance pulse that should increase.In step 225, SUS is added on the TSUSO that in Figure 10 step 201, calculates to calculate increasing and keeps the later maintenance pulse number TSUS of pulse.

Keep the sum of pulse just to increase like that as described above.

Figure 13 is a process flow diagram that provides process D.Relatively can be clear that it and Figure 12 that it and process C difference only are execution in step 226 with replacement execution in step 225, and other step is identical.In the step 226, from TSUSO, deduct SUS to reduce the number that keeps pulse.

Figure 14 is the process flow diagram that is given in the process of carrying out in the 4th embodiment 2.In step 231, each (m) son field is provided with one keeps pulsed drive cycle SFT[m].In step 232, be provided with the output of each height field and keep the number SFP[m of pulse], according to the SFT[m that is provided with in the above described manner] and SFP[m] carry out the maintenance behavior of m son field.Then m increases by 1 in step 233, carries out m+1 the maintenance behavior in the son field by repeating step 231 and 232.

Figure 15 is a sketch, and it provides an example of the process that causes the 4th embodiment, this figure and Fig. 2 correspondence.As shown in the figure, before hold period changed, SF1 was 8 μ s to the maintenance recurrence interval of SF4, SF1 to total retention time of SF4 be 1200 μ s, be 150 and keep the sum of pulse.Because the demonstration loading ratio of SF1 and SF2 is big, must prolong the maintenance recurrence interval of SF1 and SF2, but the loading ratio of SF3 and SF4 is little, thereby can be shortened rather than prolong their maintenance recurrence interval.

Describe such example among the figure, wherein the process in the 4th embodiment is used to above-mentioned situation, supposes in SF1 and SF2 keeping the recurrence interval to extend to 10 μ s, and foreshorten to 6 μ s in SF3 and SF4.Consequently the retention time of SF1 has increased by 20 μ s, from 80 μ s to 100 μ s, the retention time of SF2 has increased by 40 μ s, from 160 μ s to 200 μ s, the retention time of SF3 has reduced by 80 μ s, the retention time of SF4 has reduced by 180 μ s, and the retention time in the entire frame has reduced by 180 μ s, thereby causes the generation of unoccupied time.

If keep the number of pulse to increase by 1 in SF1, SF2 keeps the number of pulse need increase by 2,4,8 respectively in SF4 so, and the required unit interval is 1 * 10 μ s+2 * 10 μ s+4 * 6 μ s+8 * 6 μ s=102 μ s.Unoccupied time is 180 μ s as previously mentioned, thereby just may increase the unit of number that keeps pulse, and the number of the maintenance pulse from SF1 to SF4 becomes 11,22,44,88 respectively, and unoccupied time is 78 μ s.Consequently, because can increase the retention time that keeps pulse number 10% and each son field more suitably is set compared with original state, the deterioration that resembles quality as losing display dot does not just take place.Though keep the recurrence interval to change over 6 μ s or 10 μ s in this example, also can go the change cycle to arrive more suitably numerical value with the table that provides among Figure 11 from 8 μ s.

As previously mentioned, the maintenance recurrence interval of a part of son is shortened and the situation that keeps the recurrence interval to remain unchanged in other the son has been narrated in first embodiment, and the maintenance recurrence interval of a part of son is shortened and the situation that keeps the recurrence interval to be extended in other sons has been narrated in the 4th embodiment, but also can prolongation or whole maintenance recurrence intervals of son, and in other sons, remain unchanged.This following be effectively in this case, as want power controlling, thereby will reduce the sum that keeps pulse and will produce unoccupied time.

As previously mentioned,, can realize a kind of like this PDP device, wherein,, also can not lose the such deterioration that resembles quality of display dot even increase peak brightness according to the present invention.

Claims

1. plasm display device, that uses a plurality of sons by controlling different brightness ratios lights and closes a son method that realizes that gray shade scale shows, comprising:

Plasma display panel (PDP), it has a plurality of scan electrodes and keeps electrode, they extend and are positioned to mutual vicinity along same direction, and a plurality of address electrode, and address electrode is along with described a plurality of scan electrodes with keep the perpendicular direction of electrode bearing of trend to extend;

Testing circuit detects each demonstration load ratio of described a plurality of son;

Keep the recurrence interval modifier, recently change the maintenance recurrence interval of each height field according to the demonstration load that detects by described testing circuit; And

Self-adaptation keeps the pulse number modifier, by the time in a display field that causes owing to the variation that keeps the recurrence interval is changed summation, the total variation of computing time, and according to the total variation of time increase/reduce each the son maintenance pulse number.

2. the plasm display device of claim 1 also comprises:

Described self-adaptation keeps the increase/minimizing of pulse number modifier to keep the number of pulse so that keep the brightness ratio of each son field.

3. the plasm display device of claim 1 also comprises the adaption brightness means for correcting, change to proofread and correct the brightness that keeps the variation of recurrence interval to cause owing to each son field,

Wherein said self-adaptation keeps the pulse number modifier to control the number of the maintenance pulse of each son field according to the correction result of described adaption brightness means for correcting.

4. the plasm display device of claim 1, the demonstration loading ratio that wherein keeps recurrence interval modifier group field be during less than a set-point, shortens maintenance recurrence interval of each son, and when greater than this set-point, then prolong it.

5. the plasm display device of claim 1 wherein keeps the recurrence interval modifier to change and comprises a part of sub the maintenance recurrence interval of the son field with high-high brightness, or changes the maintenance recurrence interval of all son fields.

6. the plasm display device of claim 1 wherein keeps the recurrence interval modifier by this way keeping the value of recurrence interval when changing beginning to change over desired value, and promptly it changes length by length through a plurality of display fields.

7. the plasm display device of claim 1, wherein should keep recurrence interval control device when demonstration loading ratios of all son fields during less than given demonstration loading ratio, or brightness ratio is greater than the demonstration loading ratio of the son of given brightness ratio during less than described given demonstration loading ratio, and the maintenance recurrence interval of all sons is changed over same one-period.