JPH10293557A - Driving method for pdp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make reproduced image display high definition and stable by allocating a mutually different line group to each field belonging to each frame and performing the addressing of a succeeding field in parallel with sustainment of each field. SOLUTION: The respective time sequential frames F are divided into an odd field f1 and an even field f2. At the time of displaying a screen of an interlace form performing addressing for setting display contents for every field f1, f2 and sustainment for ensuring luminance in order, a mutually different line group is allocated to each field f1, f2 belonging to each frame F and addressing of the succeeding fields f2, f1 is performed in parallel with the sustainment of the respective fields f1, f2. In this method, when an image scanned by an interlace form is reproduced, the display is made to be high definition and stable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of driving a PDP (Plasma Display Panel) in which an electrode pair is provided for each line of a matrix display.

2. Description of the Related Art PDPs have been widely used for applications such as television images and computer monitors with the practical use of color screens. And it is attracting attention as a large screen flat type device for high vision.

[0003]

2. Description of the Related Art As a color display device, an AC type PDP having a three-electrode structure has been commercialized. In this configuration, a pair of sustain electrodes is arranged for each line (row) of the matrix display, and address electrodes are arranged for each column. Sustain electrodes of a total number of 2n (n is the number of lines) are arranged on the same substrate surface so that “surface discharge” along the substrate surface occurs between the sustain electrodes of each line. At the time of display, addressing for forming a charge distribution according to display contents in a line-sequential manner, and sustaining for periodically generating discharge to secure luminance are sequentially performed. That is, the sustaining is started after the line scanning for one screen for addressing is completed. Such a driving method is more reliable than a method in which sustain is started sequentially from the line after scanning, and is suitable for multi-tone display including color display.

As a gradation display method of the PDP, one frame is composed of a plurality of sub-frames weighted by the number of discharges, and addressing is performed for each sub-frame to calculate the total number of discharges of each cell (display element) in one frame. The method of setting is widely known. For example, six subframes are provided, and the ratio of the lengths of the sustain periods is 1: 2:
4: 8: 16: 32. That is, so-called “binary weighting” is performed on each subframe using a geometric progression having a common ratio of “2”. As a result, it is possible to display 64 gradations with gradation levels of “0” to “63”. This display method is similarly applied to the case of reproducing an image scanned in an interlaced format like a television. However, in the case of the interlace format, each of a plurality of fields (for example, an odd field and an even field) constituting a frame is divided into a plurality of subfields having different weights.

[0005] Color display is a kind of gradation display,
This is achieved by appropriately setting the luminance ratio of the primary colors. If there are 64 gradations per primary color, the number of display colors is 6
3 ³ become.

[0006]

SUMMARY OF THE INVENTION When the number of lines is increased in order to improve resolution and adapt to HDTV broadcasting,
The time required for addressing increases. In a normal screen display, since the frame period is specified, the number of frame divisions is inevitably reduced by prolonged addressing, and there is a problem that gradation reproducibility (color reproducibility in color display) is reduced. . When the pulse width of the addressing is shortened, the probability of occurrence of a discharge error increases, and the display is easily disturbed.

SUMMARY OF THE INVENTION It is an object of the present invention to improve the definition and stabilize the display when reproducing an image scanned in an interlaced format.

[0008]

Means for Solving the Problems k which constitutes a frame
K different line groups are assigned to (k ≧ 2) fields one by one. For example, for k = 2, which is the simplest and most common, odd lines are assigned to the first field and even lines are assigned to the second field. Then, a sustain period corresponding to each field is overlapped with an addressing period of a field (next field) subsequent to that field. Here, when the preceding field is the last field of the i-th frame, the succeeding field is the first field of the (i + 1) -th frame following the i-th frame.

By overlapping the addressing period and the sustain period, the display period of each field is substantially extended by the overlap. That is, the time that can be assigned to addressing in each field becomes longer. Therefore, higher definition can be achieved by increasing the number of lines. When a field is divided into a plurality of subfields for gradation display, the number of divisions can be increased to enhance gradation.

In the case of dividing a field, overlapping the sustain period of the last subfield in the preceding field with the addressing period of the first subfield in the succeeding field is necessary to facilitate timing setting. desirable. However, the present invention is not limited thereto, and the sustain period of any one or a plurality of subfields in the preceding field may overlap with the addressing period of the first subfield in the following field. That is, it is not necessary to start the sustaining after the addressing, and the sustaining may be started at a point in time when a predetermined time has elapsed from the addressing within a period in which the charge distribution formed by the addressing is maintained. A part of the addressing of the target line group can be temporally separated from the remaining addressing.

According to a first aspect of the present invention, there is provided a PDP provided with a pair of sustain electrodes for each line of a matrix display.
In the driving method, each of the time-series frames is divided into a plurality of fields, when performing interlaced screen display that sequentially performs addressing for setting the display content for each field and sustain for securing the luminance,
A different line group is assigned to each of the fields belonging to each of the frames, and addressing of subsequent fields is performed in parallel with sustain of each of the fields.

According to a second aspect of the present invention, in the case where each field is divided into a plurality of sub-fields having different luminance weights, and the presence or absence of light emission of a display element is selected for each sub-field to perform gradation reproduction. The addressing of the first subfield in the following field is performed in parallel with the sustain of each field.

[0013]

FIG. 1 is a schematic view of an electrode arrangement of a PDP 1 according to the present invention, and FIG. 2 is an exploded perspective view showing the internal structure of the PDP 1.

The PDP 1 is a surface discharge type PDP having a three-electrode structure. As shown in FIG. 1, the lines L1 to L of the matrix display
A pair of sustain electrodes X and Y are arranged for every n, and an address electrode A is arranged for each column. That is, a total of three electrodes correspond to the unit light emitting region EU. One sustain electrode Y of the sustain electrode pair 12 is used as a scan electrode for line selection at the time of addressing. The address electrode A is a data electrode for selecting a column. In the PDP 1, a sustain electrode pair 12 is provided for each of the lines L1 to Ln, so that a line group LA including odd-numbered lines L1, L3... L (n-1) will be described later.
And a line group LB composed of even-numbered lines L2, L4,..., Ln. The sustain electrodes X are commonly connected for each line group to simplify the drive circuit.

As shown in FIG. 2, the sustain electrodes X and Y
Each is composed of a transparent conductive film 41 and a metal film (bus conductor) 42, and is arranged on the inner surface of the glass substrate 11 on the front side. A dielectric layer 17 made of low-melting glass is provided so as to cover the sustain electrodes X and Y, and an MgO film 18 is deposited on the surface thereof. The address electrodes A are arranged on the inner surface of the glass substrate 21 on the back side. One partition 29 having a linear shape in plan view is provided between each address electrode A, and the partition 29 divides a discharge space 30 in the line direction for each sub-pixel (unit light emitting area) EU. Then, the upper part of the address electrode A and the partition 29
The phosphor layers 28 of three colors of R, G, and B for color display are provided so as to cover the wall surface on the back side including the side surfaces of. The phosphor layer 28 is locally excited by ultraviolet rays generated by surface discharge and emits visible light of a predetermined color. Each pixel EG is composed of three sub-pixels EU of R, G, B arranged in the line direction. A structure corresponding to one sub-pixel EU is a cell.

Hereinafter, a method of driving the PDP 1 will be described. In television, a frame consists of odd and even fields. In the present embodiment, different line groups LA and LB are assigned to these fields during television display. That is, the line group LA is used for displaying odd fields, and the line group LB is used for displaying even fields. This display mode is disadvantageous in terms of luminance but is advantageous in terms of resolution, as compared with a mode in which the same data is displayed two lines in each field.

FIG. 3 is a diagram showing a field configuration. To perform gradation display, the odd field f1 is divided into eight subfields sf1, sf2, sf3, sf4, sf5, s, for example.
It is divided into f6, sf7, and sf8. Similarly, the even field f2 is divided into eight subfields sf1 to sf8.
Each of the subfields sf1 to sf8 is an image of one luminance level, and each display period is composed of an address period TA and a sustain period TS that follows. In the illustrated example, the address period TA includes a reset period TAr and a scan period TAs.

The relative ratio of luminance in each of the subfields sf1 to sf8 is 1: 2: 4: 8: 16: 32: 64: 12.
The luminance of the sustain period TS of each of the subfields sf1 to sf8 is set by performing binary weighting so as to be 8. In practice, the number of sustain pulses to be applied is set.
Since the application cycle is constant, the sustain period TS becomes longer as the luminance weight increases. The length of the address period TA is determined by the total number n of lines, and is constant regardless of the luminance weight. If the total line number n is an even number, the number of lines to be addressed at one time is n / 2, and the length of the address period TA is the scan period τ (about 1 μm).
N / 2 times. Such a subfield sf1
With the combination of 8 lighting / non-lighting, 256 gradations can be realized for each of R, G, B colors.

FIG. 4 is an applied voltage waveform diagram showing an example of the driving sequence. The reset period TAr is a period for erasing wall charges of one of the line groups (here, odd-numbered lines) to be addressed to prevent the influence of the previous lighting state. A strong surface discharge occurs in response to the rise of the write pulse Pw, and a relatively large amount of wall charges is accumulated in the dielectric layer 17. Self-discharge occurs due to wall charges in response to the fall of the write pulse Pw, and the wall charges of the dielectric layer 17 disappear. The pulse Paw is applied to suppress charging of the inner wall surface on the back side.

The scan period TAs is a period in which line-sequential addressing is performed. For the target line group,
The sustain electrode X is biased to the positive potential Vax with respect to the ground potential, and the sustain electrode Y is biased to the negative potential Vsc. In this state, each line is selected one by one sequentially from the top line, and a negative scan pulse Py is applied to the sustain electrode Y. Simultaneously with the selection of the line, the peak value V is applied to the address electrode A corresponding to the cell to be turned on.
A positive address pulse Pa of a is applied. In the cell to which the address pulse Pa is applied in the selected line, a counter discharge occurs between the sustain electrode Y and the address electrode A, and wall charges are generated. Since the sustain electrode X is biased to a potential having the same polarity as the address pulse Pa, the bias cancels the address pulse Pa and no discharge occurs between the sustain electrode X and the address electrode A.

The sustain period TS is a period in which the lighting state set by addressing is maintained in order to secure luminance according to the gradation level. First, a positive sustain pulse Ps having a peak value Vs is applied to the sustain electrode Y.
Is applied. After that, a sustain pulse Ps is alternately applied to the sustain electrode X and the sustain electrode Y. Each time the sustain pulse Ps is applied, the address period T
At the end of A, surface discharge occurs in the cells where the appropriate wall charges exist.

FIG. 5 is a diagram showing the display timing of the field. As described above, when displaying the time-series frame F including the odd field f1 and the even field f2, as shown in FIG. 5A, the display period of each field f1 and f2 overlaps a part of the display period of the subsequent field. Let it. That is, the odd field f of the i-th frame F
The even field f of the i-th frame F during one display period
The display period of the odd field f2 of the (i + 1) th frame F is overlapped with the display period of the even field f2.

More specifically, by using a buffer memory, as shown in FIG. 5B, the sustain period TS of the last subfield sf8 of the preceding field is
The first subfield sf1 in the subsequent field
Is overlapped with the addressing period TA. The addressing period TA is a period for setting display contents, and is not a period for actually displaying an image. Therefore, even if the addressing of the subfield sf1 is performed in parallel with the sustain of the preceding subfield sf8, there is no problem in display.

The odd field f1 and the even field f
In each of the two, the period during which an image is actually displayed is a period from the start of the sustain of the first subfield sf1 to the end of the sustain of the last subfield sf8. In the case of a television, the actual display period only needs to be about 16.6 ms. Therefore, by overlapping the display periods as described above, the length of the display period that can be assigned to each of the odd field f1 and the even field f2 is set. Is (16.6 + α) ms. Here, α is the time required for one addressing (that is, the length of the address period TA). Since the display period of one field is substantially extended, the number of subfields can be increased to enhance the gradation, and the pulse width of the scan pulse Py can be extended to stabilize the driving.

In the non-overlapping period, the sustain electrodes X and Y are kept at the ground potential for one line group (LB or LA) not used for display. This has the following advantages: Unlike the case where the sustain pulse Ps is applied as in the case of the line group used for the display, the charging current does not flow, so that the power consumption is reduced, and unnecessary discharge that causes a decrease in contrast is prevented. Since the sustain electrodes X and Y have the same potential, electromigration of the electrodes is reduced.

In the above embodiment, the order of the subfields sf1 to sf8 does not always need to be in the order of the weight (ascending order or descending order). For example, an optimization method of arranging the subfield sf8 having a large weight in the middle of the field can be applied. However, when sustaining of the first subfield sf1 is performed following addressing as shown in FIG. 5, each of the fields f1, f2
Is made longer than the address period TA. It is desirable that the overlap time between the preceding field and the succeeding field is set to the length (maximum value) of the address period TA.
May be shorter than the length.

[0027]

According to the first or second aspect of the present invention,
Higher definition and more stable display can be achieved when reproducing an image scanned in an interlaced format.

[Brief description of the drawings]

FIG. 1 is a schematic view of an electrode arrangement of a PDP according to the present invention.

FIG. 2 is an exploded perspective view showing an internal structure of the PDP.

FIG. 3 is a field configuration diagram.

FIG. 4 is an applied voltage waveform diagram showing an example of a driving sequence.

FIG. 5 is a diagram showing display timing of a field.

[Explanation of symbols]

 1 PDP F frame f1, f2 Field L1 to Ln Line LA, LB Line group sf1 to 8 Subfield TA Address period TS Sustain period X, Y Sustain electrode

Claims (2)

[Claims] 1. A method of driving a PDP in which a pair of sustain electrodes is provided for each line of a matrix display, wherein each time-series frame is divided into a plurality of fields, and display contents are set for each of the fields. When performing interlaced screen display in which addressing to be performed and sustaining to ensure luminance are sequentially performed, different line groups are assigned to the respective fields belonging to the respective frames, and the subsequent fields are performed in parallel with the sustain of the respective fields. A method of driving a PDP, comprising: 2. The method according to claim 1, wherein each of said fields is divided into a plurality of subfields having different luminance weights, and gradation is reproduced by selecting whether or not light emission of a display element is selected in subfield units.
2. The method of driving a PDP according to claim 1, wherein the first sub-field of the subsequent field is addressed in parallel with the sustain of each field.