Panasonic Corporation

Takahiko Origuchi

Hidehiko Shoji

Mitsuo Ueda

Takateru Sawada

Tomoyuki Saito

Hideki Nakata

Kazuhiro Yamada

Toshiyuki Maeda

Minoru Takeda

Yasuaki Mutou

Akira Yawata

Hiroko Yamamoto

The image display quality is improved by uniforming the display luminance. For that purpose, the plasma display device has a plasma display panel, and image signal processing circuit. Image signal processing circuit includes loading correcting section. Section includes number-of-lit-cells calculating section for calculating the number of discharge cells to be lit for each display electrode pair in each subfield, load value calculating section for calculating the load value of each discharge cell based on the calculation result by number-of-lit-cells calculating section, correction gain calculating section for calculating the correction gain of each discharge cell based on the calculation result by load value calculating section and the positions of the discharge cells, and correcting section for subtracting, from an input image signal, the result derived by multiplying the input image signal by the output from correction gain calculating section.

Plasma display device and plasma display panel driving method

A voltage of sustain electrodes is lowered from Veto a ground potential at a time point immediately before a first SF (sub-field). Then, a pulsed positive voltage is applied to data electrodes at a starting time point of a setup period of the first SF. Immediately before this, a large amount of negative wall charges is stored on the sustain electrodes and positive wall charges are stored on the data electrodes, and therefore application of the pulsed positive voltage to the data electrodes generates strong discharges between the sustain electrodes and the data electrodes. After that, application of a ramp voltage to scan electrodes is started at a time point, generating setup discharges between the scan electrodes and the sustain electrodes.

Plasma display device and method of driving the same

Display luminance is uniformized to enhance image display quality. A sustain pulse generating circuit generates sustain pulses by selecting any one of a plurality of driving patterns, according to an all-cell light-emitting rate and a partial light-emitting rate. A loading correction part of the image signal processing circuit includes: number of lit cells calculator for calculating the number of discharge cells to be lit in each display electrode pair, in each subfield; load value calculator for calculating a load value of each discharge cell, according to the calculation result in number of lit cells calculator; correction gain calculator for calculating a correction gain of each discharge cell, according the calculation result in load value calculator, the driving pattern selected, and the position of the discharge cell; and corrector for correcting an input image signal, according to the output from correction gain calculator.

A first ramp waveform (RW) rising from a first potential (Vscn) to a second potential (Vscn+Vset) is applied to a plurality of scan electrodes (SCi) in a first period (tto t), and a driving waveform dropping from a third potential (Ve) to a fourth potential (0V) is applied to a plurality of sustain electrodes (SUi) before the first period (tto t), and the plurality of sustain electrodes are held at the fourth potential (0V) in the first period (tto t). At this time, a second ramp waveform (RW) rising from a fifth potential (0 V) to a sixth potential (Vd) according to change of a potential of the first ramp waveform (RW) is applied to a plurality of data electrodes (Dj) in a second period (tto t) that starts at a starting time point (t) of the first period (tto t) and is shorter than the first period (tto t), thereby preventing generation of strong discharges between the plurality of data electrodes (Dj) and the plurality of scan electrodes (SCi).

Driving device, driving method and plasma display apparatus

Display luminance is uniformized and the brightness is enhanced. A plasma display device has image signal processing circuit including loading correction part. The loading correction part has: number of lit cells calculator for calculating the number of discharge cells to be lit in each display electrode pair, in each subfield; load value calculator for calculating a load value of each discharge cell, according to the calculation result in number of lit cells calculator; correction gain calculator for calculating a correction gain of each discharge cell, according to the position of the discharge cell and the calculation result in load value calculator, such that the correction gain is smaller in the central portion than in the peripheral portion on the plasma display panel's image display surface; and corrector for subtracting the multiplication result of the output from correction gain calculator and an input image signal, from the input image signal.

In a two-phase driving operation that is performed in at least a sub-field having a largest luminance weight, a first ramp waveform that drops from a first potential to a second potential is applied to a plurality of first scan electrodes, a second ramp waveform that drops from a third potential that is higher than the first potential to a fourth potential that is higher than the second potential is applied to a plurality of second scan electrodes in a setup period, and a scan pulse is sequentially applied to the plurality of first scan electrodes, and then a scan pulse is sequentially applied to the plurality of second scan electrodes in a write period. The two-phase driving operation is employed to prevent a discharge failure during a write discharge.

Driving device and driving method of plasma display panel, and plasma display apparatus

A stable address discharge in a plasma display device is generated without increased voltage to cope with increase in the cumulative current-carrying time of a panel with high luminance. A cumulative time calculating circuit for calculating cumulative current-carrying time of the panel and a driving circuit for driving the panel. The driving circuit delivers collected power to the display electrode pairs and clamps each voltage of the display electrode pairs to power-supply voltage and base potential. A sustain period has a period, during which the voltage of the display electrode pairs is clamped to base potential, between the sustain pulse for generating the last sustain discharge in the sustain period and the immediately preceding sustain pulse. The length of the period is changed according to the cumulative current-carrying time calculated by the cumulative time calculating circuit.

Plasma display device and method for driving plasma display panel

In a plasma display panel apparatus, luminance when a display state of a panel is all-black is reduced. In a first period, in which a first ramp waveform dropping from a first potential to a second potential is applied to a plurality of scan electrodes, within a setup period, a second ramp waveform dropping from a third potential to a fourth potential is applied to a plurality of sustain electrodes in a second period in the case of not all-black, and a third ramp waveform dropping from the third potential to a fifth potential is applied to the plurality of sustain electrodes in a third period which is longer than the second period in the case of all-black. In addition, a scan pulse is not applied to the plurality of scan electrodes in a write period in the case of all-black.

In displaying a predetermined image on a plasma display panel, occurrence of an initializing bright point can be suppressed to reduce the maximum voltage in an all-cell initializing operation, light emission in the all-cell initializing operation is suppressed to reduce the black luminance, and the contrast is sharpened. In driving the plasma display panel, one field period includes a plurality of subfields having a setup period for causing initializing discharge in discharge cells, an address period, and a sustain period. One field period includes at least one subfield for applying ramp waveform voltage increasing in the setup period to the scan electrodes. The maximum voltage of the ramp waveform voltage can be varied. When a predetermined image establishing a previously determined condition is displayed, the ramp waveform voltage is generated whose maximum voltage is smaller than when an image other than the predetermined image is displayed, and a positive voltage is applied to the data electrodes at least while the ramp waveform voltage having the smaller maximum voltage is applied to the scan electrodes.

Plasma display device and method of driving plasma display panel

Crosstalk between adjacent discharge cells is reduced for a stable sustain discharge. A plasma display panel has scan electrodes and sustain electrodes arranged so that the positions of the corresponding scan electrode and sustain electrode are alternately interchanged in each display electrode pair, and image signal processing circuit converts an image signal into image data indicating light emission and no light emission in each discharge cell in each subfield. The image signal processing circuit generates the image data so that a combination of image data is avoided. One of two adjacent discharge cells having side-by-side scan electrodes is lit and the other of the discharge cells is unlit in one subfield of a plurality of subfields forming one field, and the one of the discharge cells is unlit and the other of the discharge cells is lit in a subfield after the one subfield in the same field.

Plasma display device and drive method of plasma display panel

One field period includes a plurality of subfields each having (i) an initialization period in which a gradually descending sloping waveform voltage is applied to a scan electrode, (ii) a writing period in which a negative scan pulse voltage is applied to the scan electrode, and (iii) a sustain period. A sloping waveform voltage is generated by switching a minimum voltage in the sloping waveform voltage between a first voltage and a second voltage that has a lower voltage value than that of the first voltage. A number of subfields, in which an initialization is carried out by the sloping waveform voltage having the minimum voltage as the second voltage, is increased when a temperature of a plasma display panel is determined to be low as compared with when the temperature is determined to be not low.

A stable address discharge is generated and number of unlit cells is decreased without heightening the voltage necessary for generating an address discharge. For this purpose, the device includes a plasma display panel and a driving circuit for driving the plasma display panel, in which the driving circuit drives the plasma display panel having a sub-field group formed of two or more continuous sub-fields for controlling addressing provided in one field period, so as not to generate sustain discharge in the discharge cell not causing sustain discharge and also in the subsequent sub-fields, the discharge cell is initialized by applying a ramp waveform voltage descending gently to the scan electrode, the lowest voltage of the ramp waveform voltage of the sub-field included in the sub-field group is made different from the lowest voltage of the ramp waveform voltage of the sub-field not included in the sub-field group.

Plasma display device and driving method of plasma display panel

A first ramp waveform rising from a first potential (Vi) to a second potential (Vi) is applied to a plurality of scan electrodes (SC) in a first half period of a setup period, and a third ramp waveform rising from a fifth potential (a ground potential) to a sixth potential (Vi, Vi') is applied to a plurality of sustain electrodes (SU) in a period, which is shorter than the first half period, within the first half period. A second ramp waveform dropping from a third potential (Vi) to a fourth potential (Vi) is applied to the plurality of scan electrodes (SC) in the second half period following the first half period, and a fourth ramp waveform dropping from a seventh potential (Ve) to an eighth potential (Vi, Vi&#x2032;) is applied to the plurality of sustain electrodes (SU) in a period, which is shorter than the second half period, within the second half period. Then, a peak value of the third ramp waveform and a peak value of the fourth ramp waveform are changed based on a state of a plasma display panel.

Plasma display device and driving method thereof

Disclosed here is a method for driving a plasma display panel and a plasma display device capable of providing image display with a high contrast ratio and excellent quality by stabilizing an address discharge. According to the method, which is the method for driving a plasma display panel in which discharge cells are formed at intersections of scan electrodes, sustain electrodes and data electrodes, the field&#x2014;that contains at least one sub-field having the all-cell initializing operation&#x2014;and the field&#x2014;that is formed of sub-fields having the selective-cell initializing operation only&#x2014;are set at a ratio of 1:N (where, N takes an integer of 1 or greater). At the same time, at least in one sub-field of the field having the selective-cell initializing operation only, the scan-pulse width employed for the selective-cell initializing field is determined longer than the scan-pulse width employed for the field containing the all-cell initializing operation.

Plasma display device and method for driving the same

In a plasma-display-panel driving method, a field period is divided into a plurality of sub fields, each of which has an address period for allowing discharge cells to selectively generate an address discharge and a sustain period for allowing the discharge cells having generated the address discharge to generate a sustain discharge by a number of times corresponding to a brightness weight. In the sustain period, a period for setting display electrode pairs to the base potential is disposed between the sustain pulse for causing the final sustain discharge in the sustain period and the previous sustain pulse. In a time interval corresponding to the lighting ratio of the discharge cells in the sub field after applying to the display electrode pairs a voltage for generating the final sustain discharge, a voltage for reducing the potential difference between electrodes of the display electrode pairs is applied to the display electrode pairs. Accordingly, it is possible to generate a stable address discharge and thus to reduce a crosstalk without increasing the voltage for generating the address discharge.

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Osaka, Japan

Takahiko Origuchi