CN102956188A - Method and device for fiving plasma display device - Google Patents

Abstract

The invention provides a method and a device for realizing self-adaptive frequency control of a plasma display device, which aims at solving the problem of the plasma display panel (PDP) display device in the prior art that the picture is unfavorable because of overflow of field synchronous signal corresponding to the waveform caused by the frequency deviation of an inputted signal. The invention adopts the technical scheme that the device comprises a signal frequency detector, an average image grade value detector, a waveform time length calculator, a time comparator and an average image grade value converter, wherein the signal frequency detector is used for detecting signal frequency of an external input image; the average image grade value detector is used for detecting an average image grade value of the external input image; the waveform time length calculator is used for calculating total time length of one field output waveform; the time comparator is used for comparing the total time length of the field waveform with the periodic length of a field synchronous signal to obtain maintaining pulse number to be deleted; and the average image grade value converter is used for updating and converting the average image grade value according to the result of the time comparator. The method and the device have the advantage that the display effect and the stability of the plasma display device can be improved.

Description

A kind of method and apparatus that drives plasma display panel device

Technical field

The present invention relates to field of display, especially relate to the method and apparatus that a kind of plasma display is realized adaptive frequency control.

Background technology

Plasmia indicating panel, when the HF voltage guiding discharge, discharge gas produces vacuum ultraviolet (Vacuum Ultraviolet ray), makes the light-emitting phosphor between interlayer, and display frame.The advantage of plasma display panel device is thin thickness and lightweight, and it is very large and have a high-resolution display device to produce size.

For the gray level of concrete manifestation image, drive plasma display panel device by a frame being divided into the several subfields with different amount of luminescence.Each subfield was divided into for the reset cycle that evenly produces discharge, was used for selecting the addressing period of discharge cell, was used for keeping the cycle according to discharge count amount concrete manifestation gray level.For example: when 256 gray level display images, will be divided into 8 subfields corresponding to 1/60 second frame period (16.67ms).Each subfield again is divided into reset cycle, addressing period and keeps the cycle, and the reset cycle of each subfield is identical with addressing period.But keep cycle and discharge number thereof in each subfield and keep number of pulses by the increase of certain ratio.Because keep the cycle difference in each subfield, so gray level that can the concrete manifestation image.

When deviation appears in the frequency of outside input picture, can directly cause the cycle of frame data to be lower than 16.67ms, at this moment these frame data overflow with respect to field sync signal that (at present two kinds of main TV broadcasting systems are NT and PAL in the world, we judge that according to the signal frequency detector then input signal belongs to NT standard or pal mode, produce the field sync signal of standard according to the standard of input signal, but the signal of input is NT or the pal mode of standard not necessarily, the deviation of the meeting frequency of occurrences, generation time is poor thus), cause display to produce flicker (Flicker) phenomenon, image quality is reduced.

Summary of the invention

The object of the invention is to: for the problem of prior art existence, provide a kind of plasma display to realize the method and apparatus of adaptive frequency control, the PDP display overflows because frequency input signal deviation waveform causes relative field sync signal in the prior art to solve, and causes occuring the bad problem of picture.

Goal of the invention of the present invention is achieved through the following technical solutions:

A kind of plasma display is realized the method for adaptive frequency control, it is characterized in that, the method may further comprise the steps: (1) gathers field sync signal Cycle Length, the average image grade point (the average image grade of outside input picture, AVERAGE PICTURE LEVEL is called for short APL), keep the T.T. length of umber of pulse A and a field wave shape; (2) deduct the field sync signal Cycle Length with the T.T. length of a field wave shape and obtain the time span that waveform overflows part; The time span of then overflowing part with waveform is divided by each time span of keeping pulse, and what obtain needing deletion keeps umber of pulse N, if remove the result remainder is arranged, then the result is rounded up to and is immediate integer; (3) then from always keep number, sequentially find from big to small the value of first difference that is less than or equal to A and N as new the average image grade point, the at last the average image grade point output that this is new also is applied in the plasma display driving voltage waveform, realizes adaptive frequency control.

Preferably, the field sync signal Cycle Length described in the step (1) is to judge according to the frequency of outside input picture to obtain.

Preferably, the field wave shape described in the step (1) T.T. length acquisition methods be: at first obtain correspondence according to the average image grade point of outside input picture and keep umber of pulse; Then keep umber of pulse and each according to correspondence and keep the time span that the cycle of pulse obtains total sustain discharge cycle of a field wave shape; The time span that at last time span in total sustain discharge cycle is added the resetting of a field wave shape, addressing period obtains the T.T. length of a field wave shape.

Preferably, always keeping number for always keeping number in the average image grade point table described in the step (3).

A kind of device of as claimed in claim 1 method is characterized in that, this device comprises:

The signal frequency detector is for the signal frequency of surveying outside input picture;

The average image grade point detector, the average image grade point that is used for outside input picture detects;

Waveform time span counter is for the T.T. length of calculating an output waveform;

The time comparer is used for the T.T. length and field sync signal Cycle Length of a field wave shape relatively, and needing to obtain the umber of pulse of keeping of deletion;

The average image grade point converter is used for averaging image gradation value renewal conversion according to the result of time comparer.

Compared with prior art, the present invention changes the umber of pulse of keeping of control waveform by the frequency according to the outside input picture that is detected by the signal frequency detector, so that the waveform of driving voltage changes to some extent, overcome exist in the prior art in plasma display apparatus because outside input picture Frequency generated is when changing, drive waveforms is kept umber of pulse and is remained unchanged and cause waveform to overflow with respect to field sync signal, and cause the flicker of plasma display panel device, affect the problem of its display effect and stability, and then can improve the stability of plasma display display effect and display.

Description of drawings

Fig. 1 has illustrated when image normally shows that a field wave shape is with respect to the synoptic diagram of field sync signal.

Fig. 2 is when the input picture frequency anomaly has been described, the waveform that may occur relatively and the synoptic diagram of field sync signal when overflowing.

Fig. 3 is the process flow diagram that key step of the present invention has been described.

Fig. 4 has illustrated according to of the present invention dynamically to adjust synoptic diagram for APL with the APL curve of external image frequency dynamic adjustment.

Embodiment

The present invention is described in detail below in conjunction with the drawings and specific embodiments.

Embodiment

Fig. 1 has illustrated when image normally shows that a field wave shape is with respect to the synoptic diagram of field sync signal.

As shown in Figure 1, in the PDP display packing, a two field picture is divided into a plurality of subfields, and each subfield comprises reset addressing cycle (reset cycle and addressing period are collectively referred to as) and sustain discharge cycle.Here describe as an example of the gray scale of 6 subfields example.One two field picture temporarily is divided into six subfields, and each subfield comprises reset addressing cycle A1 ~ A6 and sustain discharge cycle S1 ~ S6.One field wave shape Len req is T=SUM (A1:A6)+SUM (S1:S6) just, and namely reset addressing cycle A1 ~ A6 summation adds sustain discharge cycle S1 ~ S6 summation.Last keeps the distance that pulse does not exceed the synchronizing signal rising edge the normal display waveform of image.As under the NT standard, field sync period then needs T＜=16.67ms for fixing 16.67ms.

Fig. 2 is when the input picture frequency anomaly has been described, the waveform that may occur relatively and the synoptic diagram of field sync signal when overflowing.

As shown in Figure 2, Wave data has final stage to keep pulse to overflow and since signal overflow the change that must occur on the picture.Keeping pulse overflows and refers to: when field sync signal becomes 1 by 0, keep pulse and still and do not finish.Describe as an example of the gray scale of 6 subfields example equally, when plasma display panel device receives the NT signal, one field wave shape Len req is T=SUM (A1:A6)+SUM (S1:S6) just〉16.67ms, then this moment the waveform spillover has occured, the bad phenomenon such as flicker may appear in picture.

Fig. 3 is the process flow diagram of key step of the present invention.

As shown in Figure 3, plasma display panel device APL according to the present invention comprises signal frequency detector for the signal frequency of outside input picture with the control device of external image frequency dynamic adjustment; The APL detecting device that is used for the APL detection of outside input picture; Be used for calculating the waveform time span counter of an output waveform time span; Be used for the T.T. length and field sync signal Cycle Length of a field wave shape relatively, and needing obtain the time comparer of keeping umber of pulse of deletion; Be used for being used for according to the result of time comparer the APL converter of APL conversion.

When external image is inputted, calculate frequency input signal by the signal frequency detector, then (this is prior art: at present can to draw the field sync signal Cycle Length according to frequency input signal, two kinds of main TV broadcasting systems are NT and PAL in the world, judge that according to the signal frequency detector input signal belongs to NT standard or pal mode, then, produce the field sync signal of standard according to the standard of input signal), the APL detecting device calculates the APL value of input picture, and can calculate the time spans of all sustain discharge phases of a field wave shape, i.e. the T.T. length of a field wave shape by the periodic quantity that waveform time span counter is kept pulse according to APL value and known each.For example to keep umber of pulse be A to APL detecting device total APL value correspondence of calculating input picture, it is the always individual umber of pulse of keeping of total A of this field wave shape, each cycle of keeping pulse is T1, the time span Ta=A*T1 in total sustain discharge cycle of a field wave shape then, the time span Tb=SUM (A1:A6) in the reset addressing cycle of one field wave shape, i.e. A1 among Fig. 1 or Fig. 2 ~ A6 time sum.T.T. length T=the Ta+Tb of one field wave shape.

Then by the time comparer time span Tvsync of total waveform time span T and field sync signal relatively, if the waveform spillover greater than the field sync signal time span, then occurs in the waveform time span, this moment waveform to overflow the length of part be T-Tvsync.Each time span of keeping pulse is Ts, then need to delete N=CEILING((T-Tvsync)/Ts, 1) (the T.T. length that needs deletion to keep segment pulse is kept the time span of pulse divided by each, be rounded up to, needing to obtain the pulse number of keeping of deletion) the individual umber of pulse of keeping, could allow a field wave shape time span be less than or equal to the field sync signal time span; The value N that the APL converter draws according to comparer (needing the umber of pulse of keeping of deletion), in the APL table in storer, order finds a new APL from big to small from keep number, this value is for keeping first value less than or equal to An=A-N that finds in the umber of pulse always, new APL then is the APL that obtains after the conversion of APL converter; The at last the average image grade point output that this is new also is applied in the plasma display driving voltage waveform, realizes adaptive frequency control.

Table 1 APL sample table

In the table, SF1 ~ SF6 is the number of keeping such as Fig. 1 or each subfield shown in Figure 2, and allsf is total number of keeping

SF1	SF2	SF3	SF4	SF5	SF6	allsf
							1	2	4	8	16	32	63
1	2	4	8	16	32	63
							1	2	4	8	16	32	63
1	2	4	8	16	32	63
							1	2	4	8	16	31	62
1	2	4	8	16	30	61
							1	2	4	8	16	29	60
1	2	4	8	16	28	59
							1	2	4	8	16	27	58
1	2	4	8	16	26	57
							1	2	4	8	15	26	56
1	2	4	8	15	25	55
							1	2	4	8	15	24	54
1	2	4	8	14	24	53
							1	2	4	8	14	23	52
1	2	4	8	14	22	51
							1	2	4	8	14	21	50

Fig. 4 has illustrated according to of the present invention dynamically to adjust synoptic diagram for APL with the APL curve of external image frequency dynamic adjustment.Dotted line is the APL curve of setting among Fig. 4, and curve was compared with setting curve after the APL curve was dynamically adjusted shown in Fig. 4 solid line after conversion was dynamically adjusted through Fig. 3 embodiment A PL, only virgin curve was kept the many parts of umber of pulse and adjusted, and remainder does not adjust.

The above only is preferred embodiment of the present invention, not in order to limit the present invention, should be pointed out that all any modifications of doing within the spirit and principles in the present invention, is equal to replacement and improvement etc., all should be included within protection scope of the present invention.

Claims (5)

1. a plasma display is realized the method that adaptive frequency is controlled, and it is characterized in that the method may further comprise the steps:

(1) gather outside input picture field sync signal Cycle Length, the average image grade point, keep the T.T. length of umber of pulse A and a field wave shape;

(2) deduct the field sync signal Cycle Length with the T.T. length of a field wave shape and obtain the time span that waveform overflows part; The time span of then overflowing part with waveform is divided by each time span of keeping pulse, and what obtain needing deletion keeps umber of pulse N, if remove the result remainder is arranged, then the result is rounded up to and is immediate integer;

(3) then from always keep number, sequentially find from big to small the value of first difference that is less than or equal to A and N as new the average image grade point, the at last the average image grade point output that this is new also is applied in the plasma display driving voltage waveform, realizes adaptive frequency control.

2. a kind of plasma display according to claim 1 is realized the method for adaptive frequency control, it is characterized in that, the field sync signal Cycle Length described in the step (1) is to judge according to the frequency of outside input picture to obtain.

3. a kind of plasma display according to claim 1 is realized the method for adaptive frequency control, it is characterized in that, the field wave shape described in the step (1) T.T. length acquisition methods be: at first obtain correspondence according to the average image grade point of outside input picture and keep umber of pulse; Then keep umber of pulse and each according to correspondence and keep the time span that the cycle of pulse obtains total sustain discharge cycle of a field wave shape; The time span that at last time span in total sustain discharge cycle is added the resetting of a field wave shape, addressing period obtains the T.T. length of a field wave shape.

4. a kind of plasma display according to claim 1 is realized the method for adaptive frequency control, it is characterized in that, always keeping number for always keeping number in the average image grade point table described in the step (3).

5. device of method as claimed in claim 1 is characterized in that this device comprises:

The signal frequency detector is for the signal frequency of surveying outside input picture;

The average image grade point detector, the average image grade point that is used for outside input picture detects;

Waveform time span counter is for the T.T. length of calculating an output waveform;

The time comparer is used for the T.T. length and field sync signal Cycle Length of a field wave shape relatively, and needing to obtain the umber of pulse of keeping of deletion;

The average image grade point converter is used for averaging image gradation value renewal conversion according to the result of time comparer.

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