1. Field of the Invention
The present invention relates to a method for driving a plasma display panel.
2. Description of the Related Art
AC (alternating current) plasma display panels (to be referred to as PDP) are currently commercially available for use as thin display devices. A PDP houses two substrates consisting of a front transparent substrate and a rear substrate arranged in mutual opposition and separated by a predetermined gap. A plurality of row electrode pairs mutually forming pairs and respectively extending in the horizontal direction of the screen are formed on the inner surface of the front transparent substrate (surface opposing the rear substrate) serving as the display surface. Moreover, a dielectric layer covering each row electrode pair is formed on the inner surface of the front transparent substrate. A plurality of column electrodes extending in the vertical direction of the screen so as to intersect the row electrode pairs are formed on the rear substrate. When viewed from the display surface, display cells corresponding to pixels are formed at the intersections of the row electrode pairs and column electrodes.
Grayscale driving using a subfield method is carried out for this type of PDP so as to obtain half-tone display luminance corresponding to an input video signal.
In grayscale driving using a subfield method, display driving for one field's worth of a video signal is carried out for each of a plurality of subfields to which a number of times (or time period) light is to be emitted has respectively been assigned. In each subfield, an address step and a sustain step are carried out sequentially. In the address step, a selective discharge is selectively induced between the row electrodes and column electrodes in each display cell corresponding to an input video signal to form (or delete) a predetermined amount of wall charge. In the sustain step, only those display cells in which a predetermined amount of wall charge has been formed are made to discharge repeatedly to maintain a luminescent state accompanying that discharge. Moreover, a reset step is carried out prior to the address step in at least the first subfield. In this reset step, the amounts of wall charge remaining in all display cells are initialized by inducing a reset discharge between the pairs of row electrodes in all display cells.
Here, since the reset discharge is a comparatively strong discharge and is not involved in any manner with the contents of the image to be displayed, there was the problem of luminescence accompanying this discharge lowering image contrast.
Therefore, a PDP and driving method thereof have been proposed in which discharge delay time is attempted to be shortened by adhering magnesium oxide crystals, which exhibit cathode luminescence having a peak within a wavelength of 200 to 300 nm as a result of being excited by electron beam irradiation, to the surface of a dielectric layer covering row electrode pairs. For example, Japanese Patent Kokai No. 2006-54160 (Patent Document 1) discloses this PDP and its driving method. According to this PDP, since priming effects following discharge are made to persist for a comparatively long period of time, a weak discharge can be generated with stability. Therefore, by applying a reset pulse having a pulse waveform, in which the voltage value gradually reaches a peak voltage value with the passage of time, to the row electrodes of a PDP as described above, a weak reset discharge is made to occur between mutually adjacent row electrodes. In this process, since the emission luminance accompanying reset discharge decreases as a result of weakening this discharge, image contrast can be enhanced.
However, since it is not possible to adequately enhance so-called black contrast when displaying dark images even by using a driving method like that described above, there was the problem of being unable to provide dark images with high image quality.
An object of the present invention is to provide a driving method of a plasma display panel capable of enhancing the ability to express luminance contrast when displaying dark images.
A driving method for a plasma display panel according to a first aspect of the present invention is a method for driving a plasma display panel, in which a first substrate and a second substrate are arranged in opposition with a discharge space having a discharge gas sealed therein positioned between the first substrate and the second substrate, and in which display cells are formed at each intersection of a plurality of row electrode pairs formed on the first substrate and a plurality of column electrodes formed on the second substrate, the plasma display panel being driven corresponding to pixel data of each pixel based on a video signal, the method comprising: sequentially executing a reset step, in which the display cells are initialized to a state of an OFF mode by generating a reset discharge between ones of the row electrodes of the row electrode pairs and the column electrodes within the display cells by applying a voltage for using ones of the row electrodes as the anode and the column electrodes as the cathode, between the ones of the row electrodes and the column electrodes, and an address step, in which the display cells are changed to a state of an ON mode by causing the display cells to selectively address discharge, corresponding to the pixel data, said reset step and said address step being executed in at least a first subfield and a second subfield immediately following the first subfield when a display period of a single field in the video signal is divided into a plurality of subfields; executing a sustain step that causes a sustain discharge in only the display cells in the state of the ON mode by alternately applying a sustain pulse to the ones of the row electrode pairs and the others of the row electrode pairs in each subfield subsequent to the second subfield; and executing a microemission step in which a microemission discharge is generated between the ones of the row electrodes and the column electrodes within the display cells in the state of the ON mode by applying a voltage, using the ones of the row electrodes as the anode and the column electrodes as the cathode, between the ones of the row electrodes and the column electrodes while respectively applying a potential lower than the voltage generated between the ones of the row electrodes and the others of the row electrodes to the ones of the row electrodes and the others of the row electrodes when applying the sustain pulse immediately after the address step in the first subfield.
In addition, a driving method for a plasma display panel according to another aspect of the present invention is a method for driving a plasma display panel, in which a first substrate and a second substrate are arranged in opposition with a discharge space having a discharge gas sealed therein positioned between the first substrate and the second substrate, and in which display cells are formed at each intersection of a plurality of row electrode pairs formed on the first substrate and a plurality of column electrodes formed on the second substrate, the plasma display panel being driven corresponding to pixel data of each pixel based on a video signal, and the method comprising: sequentially executing a reset step, in which the display cells are initialized to a state of an OFF mode by generating a reset discharge of the display cells, an address step, in which the display cells are changed to a state of an ON mode by causing the display cells to selectively address discharge corresponding to the pixel data, and a microemission step, in which the display cells in the state of the ON mode are caused to microemission discharge, said reset step, said address step and said microemission step being executed in a first subfield when a display period of a single field in the video signal is divided into a plurality of subfields; wherein, in the reset step, the reset discharge is generated between ones of the row electrodes of the row electrode pairs and the column electrodes by applying a voltage, using the ones of the row electrodes as the anode and the column electrodes as the cathode, between the ones of the row electrodes and the column electrodes, and in the microemission step, together with generating the microemission discharge between the column electrodes and the ones of the row electrodes in the display cells in the state of the ON mode by applying a voltage, using the ones of the row electrodes as the anode and the column electrodes as the cathode, between the ones of the row electrodes and the column electrodes, a potential of the same polarity as a potential applied to the ones of the row electrodes is applied to the other row electrodes of the row electrode pairs.
A plasma display panel, in which display cells are formed at each intersection of a plurality of row electrode pairs formed on a first substrate and a plurality of column electrodes formed on a second substrate, the first substrate and second substrate being arranged in mutual opposition with a discharge space, in which a discharge gas has been sealed, positioned there between, is driven in the manner described below. Namely, a reset step, in which each display cell is initialized to an off mode by generating a reset discharge between one of the row electrodes of the row electrode pairs and the column electrodes in all of the display cells in each first and second subfield of each field, and an address step, in which the display cells are changed to an on mode by causing the display cells to selectively address discharge corresponding to pixel data, are executed sequentially. In this process, a microemission step is executed immediately after the address step in the first subfield in which a microemission discharge is generated between ones of the row electrodes and column electrodes within those display cells in the state of the one mode by applying a voltage, using the ones of the row electrodes as the anode and the column electrodes as the cathode, between both electrodes. Since this microemission discharge is generated between ones of the row electrode pairs formed on the first substrate and column electrodes formed on the second substrate, the level of emission luminance accompanying a sustain discharge, which is generated between each row electrode (one row electrode, other row electrodes) serving as row electrode pairs formed only on the first substrate, is lower than that of sustain discharge.
Here, in the microemission step, potentials lower than the voltage generated between ones of the row electrodes and the others of row electrodes during application of a sustain pulse while applying a voltage as described above between ones of the row electrodes and the column electrodes, are respectively applied to the ones of the row electrodes and the others of the row electrodes so as to prevent erroneous discharge between each of the row electrodes serving as row electrode pairs.
Accordingly, according to this form of driving, since a microemission discharge having a low emission luminance accompanying a sustain discharge in comparison with that sustain discharge can be reliably generated, differences in luminance between each gradation expressing low luminance can be minimized, thereby enhancing the ability to express luminance contrast when expressing dark images.
As shown in
Column electrodes D1 to Dm each arranged extending in the longitudinal direction (vertical direction) of a two-dimensional display screen, and row electrodes X1 to Xn and row electrodes Y1 to Yn, each arranged extending in the lateral direction (horizontal direction), are formed in the PDP 50. Row electrode pairs forming a pair with mutually adjacent row electrodes (Y1,X1), (Y2,X2), (Y3,X3), . . . (Yn,Xn) respectively serve as a first display line to an nth display line in the PDP 50. A discharge cell (display cell) PC serving as a pixel is formed at the respective intersections of each display line and each column electrode D1 to Dm (areas surrounded with alternating long and short dashed lines in
As shown in
A magnesium oxide layer 13 is formed on the surfaces of the dielectric layer 12 and augmented dielectric layer 12A. Furthermore, magnesium oxide layer 13 contains a secondary electron releasing material, which demonstrates cathode luminescence (CL) having a peak within 200 to 300 nm, and particularly within 230 to 250 nm, as a result of being excited by irradiation with an electron beam, in the form of magnesium oxide crystals (to be referred to as CL luminescence MgO crystals). These CL luminescence MgO crystals are obtained by vapor phase oxidation of magnesium vapor generated by heating magnesium, and have, for example, a polycrystalline structure consisting of mutually interlocking cubic crystals or a cubic single crystal structure. The mean particle diameter of the CL luminescent MgO crystals is 2000 Angstroms or more (result of measurement using the BET method).
In the case of attempting to form magnesium single crystals by vapor phase oxidation having a large particle diameter in which the mean particle diameter of 2000 Angstroms or more, it is necessary to raise the heating temperature when generating magnesium vapor. Consequently, the length of the flame in which the magnesium and oxygen react becomes longer, and the temperature difference between the flame and the surroundings increases. As a result, a larger number of magnesium single crystals are formed having an energy level corresponding to the peak wavelength of CL luminescence as previously described (for example, that in the vicinity of 235 nm or within 230 to 250 nm) the larger the particle diameter of the magnesium oxide single crystals formed by vapor phase oxidation.
In addition, in comparison with typical vapor phase oxidation, vapor phase oxidation magnesium single crystals formed by increasing the amount of vaporized magnesium per unit time to increase the reaction zone between magnesium and allow the magnesium to react with more oxygen has an energy level corresponding to the peak wavelength of the CL luminescence.
A magnesium oxide layer 13 is formed by adhering these CL luminescence MgO crystals to the dielectric layer 12 by a method such as spraying or electrostatic coating. Furthermore, the magnesium oxide layer 13 may also be formed by forming a magnesium oxide thin film on the surface of the dielectric layer 12 by vapor deposition or sputtering, and then adhering CL luminescence MgO crystals thereon.
On the other hand, each column electrode D is formed on the rear substrate 14 arranged in parallel with the front transparent substrate 10 in a direction perpendicular to the row electrode pairs (X,Y) at those locations in opposition to transparent electrodes Xa and Ya in each row electrode pair (X,Y). A white column electrode protective layer 15 covering the column electrodes D is further formed on the rear substrate 14. A barrier 16 is formed on this column electrode protective layer 15. This barrier 16 is formed in the shape of a ladder by lateral walls 16A, which respectively extend in the lateral direction of a two-dimensional display screen at those locations corresponding to bus electrodes Xb and Yb of each row electrode pair (X,Y), and longitudinal walls 16B, which extend in the longitudinal direction of a two-dimensional display screen at each of the intermediate locations between mutually adjacent column electrodes D. Moreover, as shown in
Furthermore, the phosphor layer 17 contains a secondary electron releasing material in the form of MgO crystals (including CL luminescence MgO crystals) in a form as shown in, for example,
Here, the magnesium oxide layer 13 is mutually enclosed between the discharge space S and gap SL of each discharge cell PC as a result of magnesium layer 13 being in contact with lateral walls 16A as shown in
The driving control circuit 56 first converts an input video signal to 8-bit pixel data that represents all of the luminance levels of each pixel in 256 gradations, followed by performing multiple gradation processing comprising error diffusion processing and dither processing on this pixel data. Namely, in the initial error diffusion processing, the upper 6 bits of the pixel data are designated as display data, while the remaining lower 2 bits are designated as error data. The result of weighted addition of error data in the pixel data corresponding to each peripheral pixel is reflected in the display data to obtain 6 bits of error diffusion processing pixel data. According to this error diffusion processing, the luminance of the lower 2 bits in raw pixels is artificially expressed by peripheral pixels, thereby enabling expression of gradation luminance equivalent to the 8 bits of pixel data with fewer than 8 bits, and namely 6 bits, of display data. Next, the driving control circuit 56 performs dither processing on the 6 bits of error diffusion processing pixel data obtained by this error diffusion processing. In this dither processing, a plurality of mutually adjacent pixels are designated as a single pixel unit, and the error diffusion processing pixel data corresponding to each pixel in this single pixel unit is respectively assigned a dither coefficient comprised of mutually different coefficient values followed by addition of these dither coefficients to obtain dither addition pixel data. As a result of adding these dither coefficients, in the case of viewing in pixel units as previously described, luminance equivalent to 8 bits can be represented with only the upper 4 bits of dither addition pixel data. Therefore, as shown in
Moreover, the driving control circuit 56 supplies various control signals for driving the PDP 50 having the previously described structure to a panel driver composed of the X electrode driver 51, the Y electrode driver 53 and the address driver 55 in accordance with an emission driving sequence as shown in
The panel driver, namely The X electrode driver 51, the Y electrode driver 53 and the address driver 55, generates various drive pulses as shown in
Furthermore,
First, in the first half of the first reset step R1 of subfield SF1, the Y electrode driver 53 applies a positive polarity reset pulse RP1Y1, in which the change in potential at the front edge over time has a gradual waveform as compared with a sustain pulse to be described later, to all row electrodes Y1 to Yn. Furthermore, the peak potential of reset pulse RP1Y1 is higher than the peak potential of the sustain pulse and lower than the peak potential of a reset pulse RP2Y1 to be described later. In addition, during this time, the address driver 55 sets column electrodes D1 to Dm to the state of a ground potential (0 volts). Moreover, during this time, the X electrode driver 51 respectively applies a reset pulse RP1X, which has the same polarity as the reset pulse RP1Y1 and a peak potential capable of preventing surface discharge between row electrodes X and Y accompanying application of the reset pulse RP1Y1, to all row electrodes X1 to Xn. Furthermore, during this time, the X electrode driver 51 may set all row electrodes X1 to Xn to a ground potential (0 volts) instead of applying reset pulse RP1x if surface discharge does not occur between row electrodes X and Y. Here, during the first half of the first reset step R1, a weak first reset discharge is respectively generated between row electrodes Y and column electrodes D in all discharge cells PC corresponding to the application of reset pulse RP1Y1 as described above. Namely, during the first half of first reset step R1, by applying a voltage between row electrodes Y and column electrodes D with the row electrodes Y serving as the anode and the column electrodes D serving as the cathode, a discharge in which current flows from the row electrodes Y to the column electrodes D (to be referred to as a column cathode discharge) is generated in the form of the first reset discharge as described above. A wall charge having negative polarity is formed near the row electrodes Y and a wall charge having positive polarity is formed near column electrodes D in all discharge cells PC corresponding to this first reset discharge.
Next, in the second half of first reset step R1 of subfield SF1, the Y electrode driver 53 generates a reset pulse RP1Y2, having a negative polarity in which the potential at the front edge changes gradually over time, and applies that reset pulse RP1Y2 to all row electrodes Y1 to Yn. Furthermore, the negative peak potential of reset pulse RP1Y2 is set to a potential that is higher than the peak potential of a writing scanning pulse SPw having negative polarity to be described later, or in other words, is set to a potential near 0 volts. Namely, if the peak potential of reset pulse RP1Y2 is lower than the peak potential of writing scanning pulse SPw, a strong discharge is generated between row electrodes Y and column electrodes D, and the wall charge formed in the vicinity of column electrodes D diminishes considerably, thereby causing the address discharge in first selective writing address step W1w to become unstable. During this time, the X electrode driver 51 sets all row electrodes X1 to Xn to a ground potential (0 volts). Furthermore, the peak potential of reset pulse RP1Y2 is the minimum potential that allows the second reset discharge described above to be reliably generated between row electrodes X and Y in consideration of the wall charges respectively formed in the vicinities of row electrodes X and Y corresponding to the first reset discharge. Here, in the second half of first reset step R1, the second reset discharge is generated between row electrodes X and Y in all discharge cells PC corresponding to application of reset pulse RP1Y2 as previously described. Due to this second reset discharge, the wall charge formed in the vicinity of each row electrode X and Y in each discharge cell PC is deleted, and all discharge cells PC are initialized to an off mode. Moreover, a weak discharge is also generated between row electrodes Y and column electrodes D in all discharge cells PC corresponding to application of the reset pulse RP1Y2. As a result of this weak discharge, a portion of the positive polarity wall charge formed in the vicinity of column electrodes D is deleted, and adjusted to an amount capable of properly generating the selective writing address discharge in the first selective writing address step W1w to be described later.
Next, in the first selective writing address step W1w of subfield SF1, the Y electrode driver 53 sequentially and alternatively applies a writing scanning pulse SPw having a peak potential of negative polarity to each row electrode Y1 to Yn while simultaneously applying, as shown in
Next, in microemission step LL of subfield SF1, the Y electrode driver 53 simultaneously applies a microemission pulse LP having a predetermined peak potential of positive polarity as shown in
Namely, in microemission step LL, as a result of applying microemission pulse LP to the row electrodes Y, a microemission discharge is generated between row electrodes Y and column electrodes D in discharge cells PC set to the on mode. Moreover, during this time, by applying XY discharge preventive pulse PV having the same polarity and same waveform as microemission pulse LP to the row electrodes X, the voltage between row electrodes X and Y is made to be lower than a discharge starting voltage, thereby preventing discharge between row electrodes Y and X. At this time, by making the respective peak potentials of microemission pulse LP and XY discharge preventive pulse PV mutually equal, the voltage applied between row electrodes Y and X may be set to 0 volts. However, although a voltage higher than the discharge starting voltage is applied between row electrodes X and column electrodes D if XY discharge preventive pulse PV is applied to the row electrodes X, as previously described, since a wall charge is not present in the vicinity of row electrodes X in discharge cells PC set to the on mode, there is no generation of a discharge between row electrodes X and column electrodes D.
In addition, as shown in
Here, this microemission discharge is a row-side cathode discharge as previously described and is generated by microemission pulse LP having a lower pulse voltage than sustain pulse IP. Accordingly, the emission luminance accompanying the microemission discharge is lower than the emission luminance accompanying the discharge of the sustain discharge (to be described later) generated between row electrodes X and Y corresponding to sustain pulse IP.
As has been described above, a discharge is generated for the microemission discharge in microemission step LL accompanying a minute emission luminance that is lower than emission luminance accompanying the first reset discharge, but has a lower luminance level accompanying that discharge than the sustain discharge and is of a degree that allows it be used for display. In the first selective writing address step W1w executed immediately before microemission step LL, a selective writing address discharge is generated between the column electrodes D and the row electrodes Y within the discharge cell PC. Accordingly, in the subfield SF1, luminance corresponding to a gradation of luminance one step higher than luminance level 0 is expressed by luminescence accompanying the selective writing address discharge and luminescence accompanying the above-mentioned microemission discharge.
Furthermore, a wall charge having a negative polarity in the vicinity of row electrodes Y and a wall charge having a positive polarity in the vicinity of column electrodes D are respectively formed following the microemission discharge described above.
Next, in the first half of second reset step R2 of subfield SF2, the Y electrode driver 53 applies a positive polarity reset pulse RP2Y1, having a waveform in which the change in potential at the front edge over time is more gradual as compared with the subsequent reset pulse, to all row electrodes Y1 to Yn. Furthermore, the peak potential of the reset pulse RP2Y1, is higher than the peak potential of the above-mentioned reset pulse RP1Y1. In addition, during this time, the address driver 55 sets the column electrodes D1 to Dm to the ground potential (0 volts), and the X electrode driver 51 respectively applies a positive polarity reset pulse RP2x, having a peak potential capable of preventing surface discharge between the row electrodes X and Y accompanying application of the reset pulse RP2Y1, to all row electrodes X1 to Xn. Furthermore, if a surface discharge does not occur between row electrodes X and Y, the X electrode driver 51 may be made to set all row electrodes X1 to Xn to the ground potential (0 volts) instead of applying the reset pulse RP2x. A first reset discharge weaker than the column-side cathode discharge is generated in microemission step LL between the row electrodes Y and the column electrodes D within the discharge cell PC in which a discharge was not generated in microemission step LL within each discharge cell PC corresponding to the application of reset pulse RP2Y1. Namely, in the first half of second reset step R2, a column-side cathode discharge, in which current flows from the row electrodes Y to the column electrodes D, is generated for the first reset discharge by applying a voltage between both electrodes with row electrodes Y serving as the anode and column electrodes D serving as the cathode. On the other hand, in those discharge cells PC in which the microemission discharge has already been generated in the microemission step LL, a discharge does not occur even if the reset pulse RP2Y1 is applied. Thus, immediately after completion of the first half of the second reset step R2, a state results in which a negative polarity wall charge is formed in the vicinity of the row electrodes Y and a positive polarity wall charge is formed in the vicinity of column electrodes D within all discharge cells PC.
Next, in the second half of the second reset step R2 of the subfield SF2, the Y electrode driver 53 applies a negative polarity reset pulse RP2Y2, in which the change in potential at the front edge over time is gradual, to the row electrodes Y1 to Yn. Moreover, in the second half of second reset step R2, the X electrode driver 51 respectively applies a base pulse BP+ having positive polarity and a predetermined base potential to the row electrodes X1 to Xn. A second reset discharge is generated between the row electrodes X and Y in all discharge cells PC corresponding to the application of the negative polarity reset pulse RP2Y2 and the positive polarity base pulse BP+. Furthermore, the respective peak potentials of the reset pulse RP2Y2 and the base pulse BP+ are the minimum potentials that allow the second reset discharge to be reliably generated between row electrodes X and Y in consideration of the wall charges formed by the first reset discharge in the vicinity of each row electrode X and Y. In addition, the negative peak potential during reset pulse RP2Y2 is set to be higher than the peak potential of negative polarity writing scanning pulse SPw, namely to a potential near 0 volts.
Namely, if the peak potential of the reset pulse RP2Y2 is lower than the peak potential of the writing scanning pulse SPw, a strong discharge is generated between the row electrodes Y and the column electrodes D, the wall charge formed in the vicinity of column electrodes D is diminished considerably, and the address discharge of second selective writing step W2w becomes unstable. Here, due to the second reset discharge generated in the second half of second reset step R2, the wall charge formed in the vicinity of each row electrode X and Y in each discharge cell PC is deleted, and all discharge cells PC are initialized to the off mode. Moreover, a weak discharge is also generated between the row electrodes Y and the column electrodes D in all discharge cells PC corresponding to the application of reset pulse RP2Y2, and as a result of this discharge, and a portion of the positive polarity wall charge formed in the vicinity of the column electrodes D is deleted and adjusted to an amount capable of properly generating the selective writing address discharge in second selective writing address step W2w.
Next, as shown in
Next, in the sustain step I of the subfield SF2, the Y electrode driver 53 generates a single sustain pulse IP having a peak potential of positive polarity, and respectively applies that pulse to the row electrodes Y1 to Yn. During this time, the X electrode driver 51 sets the row electrodes X1 to Xn to a ground potential (0 volts), while the address driver 55 sets the column electrodes D1 to Dm to a ground potential (0 volts). A sustain discharge is then generated between the row electrodes X and Y within discharge cells PC set to the on mode in the manner described above corresponding to the application of sustain pulse IP. As a result of light radiated from the phosphor layer 17 accompanying this sustain discharge being radiated to the outside through the front transparent substrate 10, a single display emission is executed corresponding to the luminance weighting of this subfield SF1. In addition, a discharge is also generated between the row electrodes Y and the column electrodes D in the discharge cells PC set to the on mode corresponding to the application of this sustain pulse IP. Due to this discharge and the sustain discharge mentioned above, a negative polarity wall charge in the vicinity of the row electrodes Y, and positive polarity wall discharges in the vicinities of the row electrodes X and the column electrodes D are respectively formed in the discharge cells PC. Following application of this sustain pulse IP, as shown in
Next, in each selective erase address step WD of the subfields SF3 to SF14, the Y electrode driver 53 sequentially and alternatively applies a deletion scanning pulse SPD having a peak potential of negative polarity to each row electrode Y1 to Yn as shown in
Next, in sustain step I of each subfield SF3 to SF14, as shown in
Following completion of the sustain step I of the last subfield SF14, the Y electrode driver 53 applies an elimination pulse EP having a peak potential of negative polarity to all row electrodes Y1 to Yn. An elimination discharge is then generated in only those discharge cells PC in the on mode corresponding to application of this elimination pulse EP. The discharge cells PC in the on mode are changed to the state of the off mode as a result of this elimination discharge.
As has been described above, driving is executed on the basis of 16 types of pixel driving data GD as shown in
First, in a second gradation expressing luminance one level higher than a first gradation expressing a black display (luminance level 0), the selective writing address discharge for setting a discharge cell PC to the on mode is generated only in the subfield SF1 of the subfields SF1 to SF14 as shown in
Next, in a third gradation expressing luminance one level higher than the second gradation, a selective writing address discharge for setting a discharge cell PC to the on mode is generated in the subfield SF2 only of the subfields SF1 to SF14 (indicated with double circles). A selective erase address discharge for changing the discharge cell PC to the off mode is generated in the following subfield SF3 (indicated with black circles). Accordingly, luminance accompanying a single sustain discharge occurs only in the sustain step I of the subfield SF2 among the subfields SF1 to SF14 in the third gradation, and luminance corresponding to luminance level “1” is expressed.
Next, in a fourth gradation expressing luminance one level higher than the third gradation, a selective writing address discharge for setting a discharge cell PC to the on mode is first generated in the subfield SF1, and the discharge cell PC set to the on mode is made to under the microemission discharge (indicated with squares). Moreover, in this fourth gradation, a selective writing address discharge for setting the discharge cell PC to the on mode is generated only in the subfield SF2 of the subfields SF1 to SF14 (indicated with double circles), and a selective erase address discharge for changing the discharge cell PC to the off mode is generated in the following subfield SF3 (indicated with black circles). Accordingly, in the fourth gradation, since luminescence of a luminance level “α” occurs in subfield SF1, and a single sustain discharge is executed accompanying luminescence of a luminance level “1” in SF2, luminance is expressed corresponding to a luminance level of “α”+“1”.
In addition, in each of the fifth to sixteenth gradations, a selective writing address discharge for setting a discharge cell PC to the on mode is generated in subfield SF1, and the discharge cell PC set to the on mode is made to undergo the microemission discharge (indicated with squares). A selective erase address discharge for changing the discharge cell PC to the off mode is then generated only in the single subfield corresponding to that gradation (indicated with black circles). Accordingly, in each of the fifth to sixteenth gradations, after the microemission discharge is generated in the subfield SF1 and a single sustain discharge is generated in SF2, a number of sustain discharges assigned to a particular subfield is generated in each of a number of continuous subfields corresponding to that gradation (indicated with white circles). As a result, in each of the fifth to sixteenth gradations, luminance is visualized corresponding to a luminance level “α”+“total number of sustain discharges generated during the display period of one field (or one frame)”.
Namely, according to the driving as shown in
According to this driving, since regions in which luminescence patterns thereof (on state, off state) are mutually inverted within the display period of a single field are not present in combination on a single screen, false contour that occurs in such states is prevented.
Here, in the case of driving as shown in
Moreover, in the case of driving as shown in
In addition, in the case of driving as shown in
In addition, in the case of driving as shown in
In addition, in the case of driving as shown in
In addition, in the case of driving as shown in
In addition, in the PDP 50 shown in
The following provides an explanation of the action and effects obtained by employing this type of constitution with reference to
Furthermore,
On the other hand,
As shown in
Thus, as shown in
Namely, as a result of applying the reset pulses RP1Y1 and RP2Y1 as shown in
Furthermore, the waveform during the rise interval of reset pulses RP1Y1 and RP2Y1 is not limited to that having a constant slope as shown in
In addition, although the PDP 50 is driven in accordance with an emission driving sequence employing a selective erase address method as shown in
Namely, the driving control circuit 56 supplies various control signals to a panel driver for sequentially executing driving in accordance with each first reset step R1, first selective writing address step W1w and microemission step LL in first subfield SF1 during the display period of one field (one frame) as shown in
The panel driver, namely the X electrode driver 51, the Y electrode driver 53 and the address driver 55, generate various drive pulses as shown in
Furthermore,
First, in second selective writing address step W2w of each subfield SF2 to SF14, the Y electrode driver 53 sequentially and alternatively applies a writing scanning pulse SPw having a peak potential of negative polarity to each row electrode Y1 to Yn while simultaneously applying a base pulse BP− having a predetermined base potential of negative polarity to the row electrodes Y1 to Yn. During this time, the X electrode driver 51 respectively applies a base pulse BP+ having a predetermined base potential of positive polarity to the row electrodes X1 to Xn. Furthermore, each potential of the base pulse BP− and the base pulse BP+ is set so that the voltage between row electrodes X and Y during the time writing scanning pulse SPw is not applied is lower than the discharge starting voltage of discharge cell PC. Moreover, in second selective writing address step W2w, the address driver 55 first converts the pixel driving data bit corresponding to each subfield (SF2 to SF14) to a pixel data pulse DP having a pulse voltage corresponding to the logic level thereof. For example, in the case a pixel driving data bit is supplied having a logic level of 1 for setting a discharge cell PC to the on mode, the address driver 55 converts this to a pixel data pulse DP having a peak potential of positive polarity. On the other hand, in the case of a pixel driving data bit having a logic level of 0 for setting a discharge cell PC to the off mode, the address driver 55 converts this to a pixel data pulse DP having a low voltage (0 volts). The address driver 55 then applies this pixel data pulse DP to the column electrodes D1 to Dm in synchronization with the timing at which each writing scanning pulse SPw is applied one display line (m pulses) at a time. At this time, simultaneous to the writing scanning pulse SPw, a selective writing address discharge is generated between the column electrodes D and the row electrodes Y in discharge cell PC to which pixel data pulse DP has been applied at a high voltage to set to the on mode. Moreover, immediately after this selective writing address discharge, a weak discharge is also generated between the row electrodes X and Y within this discharge cell PC. In other words, after the writing scanning pulse SPw has been applied, although a voltage corresponding to base pulse BP− and base pulse BP+ is applied between row electrodes X and Y, since this voltage is set to a voltage lower than the discharge starting voltage of each discharge cell PC, discharge does not occur within discharge cell PC as a result of applying this voltage alone. However, when the selective writing address discharge is generated, a discharge is generated between the row electrodes X and Y only by the application of the voltage based on the base pulse BP− and the base pulse BP+ as a result of being induced by this selective writing address discharge. Such discharge is not generated in the first selective writing address step W1w in which the base pulse BP+ is not applied to the row electrodes X. As a result of this discharge and the selective writing address discharge previously described, this discharge cell PC is set to a state in which a positive polarity wall charge in the vicinity of row electrodes Y thereof, a negative polarity wall charge in the vicinity of row electrodes X, and a negative polarity wall charge in the vicinity of the column electrodes D are respectively formed, namely to the on mode. On the other hand, a selective writing address discharge as described above is not generated between the column electrodes D and the row electrodes Y in discharge cell PC to which a pixel data pulse DP having a low voltage (0 volts) has been applied to set to the off mode simultaneous to the above-mentioned writing scanning pulse SPw, and for this reason, a discharge does not occur between the row electrodes X and Y either. Accordingly, this discharge cell PC is maintained in the immediately previous state (off mode or on mode).
Next, in sustain step I of subfield SF2, the Y electrode driver 53 generates a single sustain pulse IP having a peak potential of positive polarity, and simultaneously applies that pulse to each row electrode Y1 to Yn. During this time, the X electrode driver 51 sets the row electrodes X1 to Xn to a ground potential (0 volts), while the address driver 55 sets the column electrodes D1 to Dm to a ground potential (0 volts). A sustain discharge is then generated between the row electrodes X and Y in the discharge cells PC set to the on mode corresponding to the application of sustain pulse IP. As a result of light radiated from the phosphor layer 17 accompanying this sustain discharge being radiated to the outside through the front transparent substrate 10, a single display emission is executed corresponding to the luminance weighting of this subfield SF2. In addition, a discharge is also generated between the row electrodes Y and the column electrodes D in the discharge cells PC set to the on mode corresponding to the application of this sustain pulse IP. Due to this discharge and the sustain discharge mentioned above, a negative polarity wall charge in the vicinity of row electrodes Y, and positive polarity wall discharges in the vicinities of row electrodes X and column electrodes D are respectively formed in discharge cells PC.
Next, in an elimination step E of each subfield SF2 to SF14, the Y electrode driver 53 applies a negative polarity elimination pulse EP to the row electrodes Y1 to Yn having the same waveform as reset pulse RP2Y2 applied in the second half of the first reset step R1 and the second reset step R2. During this time, the X electrode driver 51 applies the base pulse BP+ having the predetermined base potential of positive polarity to all row electrodes X1 to Xn in the same manner as the second half of the second reset step R2. A weak elimination discharge is then generated in discharge cells PC in which a sustain discharge has been generated as previously described corresponding to this elimination pulse EP and the base pulse BP+. As a result of this elimination discharge, a portion of the wall charge formed in the discharge cell PC is deleted, and this discharge cell PC is changed to the off mode. Moreover, a weak discharge is also generated between column electrodes D and row electrodes Y in discharge cell PC corresponding to the application of this elimination pulse EP. As a result of this discharge, wall charge of positive polarity formed in the vicinity of the column electrodes D is adjusted to an amount that allows the proper generation of a selective writing address discharge in the subsequent second selective writing address step W2w. Furthermore, in each subfield SF3 to SF14, the second selective writing address step W2w is executed instead of the selective erase address step WD.
Next, in sustain step I of each subfield SF3 to SF14, as shown in
Here, in a second gradation expressing luminance one level higher than a first gradation expressing a black display (luminance level 0), a selective writing address discharge is generated only in the subfield SF1 of the subfields SF1 to SF14 based on the driving shown in
According to this driving, halftone luminance can be displayed for (N+1) gradations (N: number of subfields in the display period of one field) similar to
According to the driving shown in
Accordingly, in the driving of the PDP 50, in the case of employing driving as shown in
Furthermore, although MgO crystals are contained in the phosphor layer 17 provided on rear substrate 14 of the PDP 50 in the embodiment shown in
In addition, although microemission pulse LP and reset pulse RP2Y1 are collectively applied to the row electrodes Y in the embodiment shown in
In addition, although reset steps (R1, R2) and selective writing address steps (W1w, W2w) are sequentially executed in only the first subfield SF1 and the second subfield SF2 in the above-mentioned embodiment, this series of operations may also be similarly executed in the third subfield and beyond.
In addition, microemission step LL is executed instead of sustain step I as the step for carrying out luminescence involving a display image in the above-mentioned embodiment, but only in the first subfield SF1. However, microemission step LL may also be executed instead of sustain step I in a subfield other than the first subfield or in a plurality of subfields including the first subfield.
In addition, although a reset discharge is generated en bloc for all discharge cells in reset step R shown in
In addition, in the case of driving as shown in
This application is based on Japanese Patent Application No. 2006-291274 which is hereby incorporated by reference.
Number | Date | Country | Kind |
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2006-291274 | Oct 2006 | JP | national |