JP2007108778A - Driving method of plasma display panel and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase luminance and to provide a PDP of high definition and high image quality, by improving the contrast ratio by suppressing unnecessary discharge during image display, making driving fast, by suppressing discharge delay, significantly improving flickers, roughness, etc., of a screen due to writing defects and decrease in discharge probability of a starting pulse in a sustain period, and to improve the light emission efficiency of the PDP, by reducing reactive power of discharge during the sustain period. <P>SOLUTION: There is provided a driving method of the plasma display panel, having a plurality of discharge cells having pairs of first and second electrodes, the driving method being characterized as having an initialization period for initialization, wherein a pulse having, such a waveform that the mean value of a voltage variation rate during rising is 1 to 9V/μs, and the voltage variation rate when the voltage begins to drop is larger than the mean value of the voltage variation rate during the rising is applied to the discharge cells. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a driving method of a plasma display panel used for image display of a computer, a television or the like, and an image display device using the driving method.

[Panel structure]
In recent years, image display apparatuses such as computer displays and televisions have been desired to be increased in size, and accordingly, plasma display panels (hereinafter abbreviated as PDPs) have attracted attention as thin and lightweight displays.

  Conventional PDPs are generally configured as shown in FIG.

  In FIG. 5, a strip-shaped scan electrode group 19a and a strip-shaped sustain electrode group 19b are formed on the front substrate 11, and the electrode groups 19a and 19b are covered with a dielectric glass layer 17 made of lead glass or the like. The surface of the dielectric glass layer 17 is covered with a protective layer 18 made of an MgO vapor deposition film or the like. On the back substrate 12, a band-shaped data electrode group 14 and an insulating layer 13 made of lead glass or the like covering the surface are provided, and a partition wall 15 is disposed thereon. The front substrate 11 and the rear substrate 12 are combined so that the respective electrode groups are orthogonal to each other. The partition wall 15 is bonded to the back substrate 12 and is in contact with the front substrate 11. The front substrate 11 and the rear substrate 12 are opposed and sealed in parallel with each other by a partition wall 15 at an interval of about 100 to 200 microns.

  By selectively applying a voltage between the electrode groups 19a, 19b on the front substrate 11 and the data electrode group 14 on the rear substrate 12, charges generated by the gas discharge at the intersection of the selected electrodes are dielectric glass. The AC pulse voltage is applied between the electrode group 19a and the electrode group 19b on the front substrate 11 after an address operation for accumulating the pixel information for one screen by scanning the electrode to which the voltage is to be applied. The discharge cells selected in the address operation emit light all at once by the sustain discharge operation to apply an image to display an image. Since the discharge occurs in a space separated by the front substrate 11, the rear substrate 12, and the partition 15, the light emission does not diffuse. That is, the partition wall 15 has a purpose of defining the distance between the front substrate 11 and the back substrate 12 and a purpose of performing display with high resolution.

  Further, when performing color display, the phosphor 16 is applied to the periphery of the discharge space blocked by the barrier ribs. Phosphors are produced by converting ultraviolet rays generated by discharge into visible light. Therefore, phosphors of three primary colors, red (R), green (G), and blue (B), are used, and the emission intensity of each is increased. By appropriately adjusting, color display becomes possible.

  As the discharge gas, in the case of monochromatic display, a mixed gas centered on neon that emits light in the visible range during discharge, and in the case of color display, xenon that emits light during discharge in the ultraviolet region. Is selected. Assuming the use of PDP under atmospheric pressure, the gas pressure is usually set in the range of about 200 Torr to 500 Torr so that the inside of the substrate is reduced with respect to the external pressure. FIG. 2 shows an electrode matrix diagram of a conventional PDP.

  Next, a conventional PDP driving method will be described with reference to FIG.

  In FIG. 3, first, an initialization pulse is applied to the scan electrode groups 19a1 to 19aN to initialize wall charges in the discharge cells of the panel. Next, a scanning pulse is simultaneously applied to the first electrode 19a1 of the scanning electrode group 19a, and a writing pulse is simultaneously applied to the lines 141 to 14M corresponding to the discharge cells for displaying the data electrode group 14, thereby performing a writing discharge to perform the surface of the dielectric layer. Accumulate wall charges. Next, a scanning pulse is applied simultaneously to the second electrode 19a2 of the electrode group 19a, and a writing pulse is simultaneously applied to the lines 141 to 14M corresponding to the discharge cells for displaying the data electrode group 14, thereby performing a writing discharge on the surface of the dielectric layer. Accumulate wall charges. Subsequently, a wall image corresponding to a cell to be displayed in the same continuous scan is sequentially accumulated on the surface of the dielectric layer, thereby writing a latent image for one screen.

  Next, in order to perform a sustain discharge, the data electrode group 14 is grounded, and a sustain pulse is alternately applied to the scan electrode group 19a and the sustain electrode group 19b. A discharge occurs when the potential of the dielectric surface exceeds the discharge start voltage, and the main discharge of the display cell selected by the writing pulse is maintained during the period in which the sustain pulse is applied (sustain period). After that, by applying a narrow erase pulse, an incomplete discharge occurs and the wall charges disappear, so that erase is performed.

  As described above, in the conventional PDP driving method, display is performed by a series of sequences of an initialization period, a writing period, a sustain period, and an erasing period. In the case of displaying a television image, the image is composed of 60 frames per second in the NTSC system. Originally, the plasma display panel can express only two gradations of lighting or extinguishing, so in order to display an intermediate color, the lighting time of each color of red (R), green (G), and blue (B) is time-divided, A method is used in which one frame is divided into several subfields and intermediate colors are expressed by combinations thereof.

  FIG. 4 shows a subfield dividing method when 256 gradations of each color are expressed in a conventional plasma display panel. The ratio of the number of sustain pulses to be applied within the discharge sustain period of each subfield is binary weighted as 1, 2, 4, 8, 16, 32, 64, 128, and 256 gradations are obtained by combining these 8 bits. Is expressed.

  However, the above-described conventional driving method has a problem that the entire panel emits light due to the discharge generated when the initialization pulse preceding the writing period and the erasing pulse after the sustain period are applied, thereby reducing the contrast.

  In addition, since the number of scanning lines of the panel increases as the definition becomes higher, in order to complete the scanning of all scanning pulses within a certain writing period, it is necessary to reduce the width of the scanning pulse and the writing pulse. For example, for high-definition display such as HDTV, it is necessary to drive these pulses at a very high speed of about 1.25 μs.

  However, in general, in a PDP, there is a discharge delay of about several hundred ns to several μs from when a pulse is applied to when light emission by discharge is performed, and with a pulse width of about 1.25 μs, the discharge probability decreases, This caused an extreme deterioration in image quality due to poor writing. In order to suppress this, the voltage of the write pulse must be increased. However, the data driver for driving the write pulse has a lower withstand voltage for high-speed driving, and cannot sufficiently increase the voltage of the write pulse. It had a very big problem.

  The present invention solves the above-mentioned conventional problems. As a first object, the contrast ratio is improved by suppressing unnecessary discharge during image display, or the drive speed is increased by suppressing discharge delay. , Drastically improve screen flickering, graininess, etc. due to write failure and lower discharge probability in the first pulse of the sustain period, and as a second objective, improve the luminous efficiency of the PDP by reducing the reactive power of the discharge during the sustain period Accordingly, an object is to provide a high-definition and high-quality PDP by increasing luminance.

  In order to achieve the above object, the present invention provides a driving method of a plasma display panel in which a plurality of discharge cells having first and second electrode pairs are formed, the driving method including initialization When the average value of the voltage change rate when rising during the initialization period is not less than 1 V / μs and not more than 9 V / μs, and when the voltage change rate when starting to fall increases This is a method for driving a plasma display panel, in which a pulse having a waveform larger than the average value of the voltage change rates is applied to the discharge cells.

  The present invention is also a driving method of a plasma display panel in which a plurality of discharge cells having a pair of first and second electrodes are formed, the driving method being input with an initialization period for performing initialization. A writing period in which writing is performed based on the image data, and the average value of the voltage change rate when rising during the initialization period is 1 V / μs or more and 9 V / μs or less, and falls. A pulse having a waveform larger than an average value of the voltage change rate at the time of starting voltage change is applied to the discharge cell through the first electrode, and the write pulse is passed through the first electrode during the write period. A method of driving a plasma display panel applied to the discharge cell.

  In the present invention, a first substrate on which a plurality of pairs of first and second electrodes are arranged and a second substrate on which a plurality of third electrodes are arranged are arranged at intervals, and the first and second substrates are arranged. A plasma display panel in which a plurality of discharge cells having the first, second, and third electrodes are formed, and an initialization period for performing initialization in one frame, and applying a pulse to the discharge cells. An image display device including a driving circuit for driving the plasma display panel, wherein the driving circuit has an average voltage change rate of 1 V / μs or more during the initialization period, 9 V / An image display device configured to apply to the discharge cell a pulse having a waveform that is equal to or less than μs and that has a voltage change rate when starting to decrease is greater than an average value of the voltage change rate when increasing.

  In the present invention, a first substrate on which a plurality of pairs of first and second electrodes are arranged and a second substrate on which a plurality of third electrodes are arranged are arranged at intervals, and the first and second substrates are arranged. A plasma display panel in which a plurality of discharge cells having the first, second and third electrodes are formed in between, an initialization period in which initialization is performed in one frame, and writing based on input image data An image display device including a driving period for applying a pulse to the discharge cell to drive the plasma display panel, wherein the driving circuit rises during the initialization period. A pulse having an average voltage change rate of 1 V / μs or more and 9 V / μs or less and a waveform having a waveform larger than the average value of the voltage change rate when the voltage change rate when starting to decrease is higher Through the first electrode The image display device is configured to be applied to the discharge cell for the first time and to apply the write pulse to the discharge cell through the first electrode during the write period.

  According to the present invention, there is provided a driving method of a plasma display panel in which a plurality of discharge cells having a pair of first and second electrodes are formed, the driving method having an initialization period for performing initialization, During the initialization period, the average value of the voltage change rate when it rises is 1 V / μs or more and 9 V / μs or less, and the voltage change rate when it starts to fall is the voltage change rate when it rises By using a plasma display panel driving method in which a pulse having a waveform larger than the average value is applied to the discharge cells, a remarkable effect of realizing a high-definition and very high-quality PDP can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The basic structure of the PDP panel used in the present invention is the same as the conventional one. Examination of the change in the light emission efficiency depending on the driving waveform was performed with various waveforms by amplifying the output of the arbitrary waveform generator with a high-speed high-voltage amplifier and applying it to the discharge cell of the PDP. In addition, using a principle similar to that of a Soya tower circuit used for characteristic evaluation of a ferroelectric material, etc., a change in the charge amount Q accumulated in the discharge cell due to the voltage V applied to the discharge cell is represented by a VQ Lissajous figure. By observing, a relative comparison was made of the power consumed in the discharge cells by the discharge.

  At the same time, the emission peak waveform was observed using the photodiode PD, the emission luminance was compared relative to the integrated value of the emission peak, and the emission efficiency of the PDP was compared. The contrast was measured by lighting a part of the panel white in a dark room and measuring the luminance ratio between the dark part and the bright part.

  Hereinafter, specific drive waveforms will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a timing chart showing a driving method according to the first embodiment of the present invention.

  The difference from the conventional PDP driving method is that the rising edge of the initialization pulse is raised in two stages.

  FIG. 6 shows the ratio tp / tw of the flat width of the first stage to the pulse width and the ratio V1 / Vst of the voltage of the first stage and the maximum voltage of the pulse in a stepped waveform in which the rising edge of the initialization pulse has two stages. The relationship of contrast is shown. The contrast is high within the shaded area and is not very practical outside this area. Outside this region, the luminance variation due to defective writing is large.

  This is because, in the prior art, a strong discharge is generated by applying a voltage in one stage and abrupt voltage changes, so that the entire surface emits light strongly due to an unnecessary initialization pulse, and the discharge cells in the panel vary. The variation in the wall charge amount after application of the initialization pulse due to the above causes a partial writing failure and causes the luminance variation, whereas in the first embodiment, a two-step staircase waveform is used. Thus, weak discharge is performed and sufficient wall charge is obtained, thereby improving luminance variation due to writing failure and suppressing light emission on the entire surface. In addition, by performing initialization with a plurality of weak discharges, the occurrence of abnormal light emission discharge is suppressed, so that stable initialization can be performed even with a short pulse width, so the initialization period is shortened and the drive speed is increased. Can be realized.

  As is clear from this, the PDP driving method according to the first embodiment suppresses writing defects, suppresses light emission due to the initialization pulse, widens the operating margin, and significantly improves the contrast. Very good image quality is achieved.

  In the first embodiment, the rising edge of the initialization pulse has a two-stage stepped pulse waveform, but it goes without saying that excellent image quality can be realized even with a multi-stage stepped pulse having three or more stages.

(Embodiment 2)
FIG. 7 shows a timing chart of drive waveforms according to the second embodiment of the present invention.

  The difference from the first embodiment is that the fall of the initialization pulse is raised in two stages.

  FIG. 8 shows the ratio tp / tw of the flat portion width and the pulse width of the first stage and the ratio V1 / Vst of the voltage of the first stage and the maximum voltage of the pulse in a stepped waveform in which the falling edge of the initialization pulse has two stages. The relationship of the contrast with respect to is shown. The contrast is high within the shaded area and is not very practical outside this area. Outside this region, the luminance variation due to defective writing is large.

  This is because, in the prior art, the self-erase discharge is generated due to a voltage drop in one step and a sudden voltage change, so that light emission from the entire surface due to an originally unnecessary initialization pulse occurs and is formed at the rising edge of the initialization pulse. In contrast to the fact that a part of the wall charges disappeared by the self-erasing discharge and the priming effect was reduced, the second embodiment suppresses the entire light emission by the self-erasing discharge by lowering the voltage in two steps. In addition, the extinction of excessive wall charges is also suppressed. In addition, by suppressing self-erasing discharge, stable initialization can be performed even with a short pulse width, so that the initialization period can be shortened and the drive speed can be increased.

  As is clear from this, the driving method of the PDP according to the second embodiment is very effective in that the light emission is suppressed without impairing the priming effect for facilitating the write discharge, and the contrast is remarkably improved. Excellent image quality can be achieved.

  In the second embodiment, the falling edge of the initialization pulse has a two-stage stepped pulse waveform, but it goes without saying that excellent image quality can be realized even with a multi-stage stepped pulse having three or more stages.

(Embodiment 3)
FIG. 9 shows a timing chart of drive waveforms according to the third embodiment of the present invention.

  The difference from the first embodiment is that the rising edge of the initialization pulse after the second stage is changed in five stages and driven at various average change speeds α [V / μs]. In order to investigate the dependence of the driving condition on the average rate of change of the rise, the wall charge movement amount ΔQ [pC before and after the write discharge generated when the write pulse is applied to the PDP using a wall charge measuring device. ] And the write pulse voltage Vdata [V].

  FIG. 10 shows an example of the dependence of ΔQ on Vdata when driving at various average change speeds. The voltage of the first stage of the initialization pulse was set to 180V, which is 20V lower than the discharge start voltage.

  It can be seen that by increasing Vdata, ΔQ increases, and the amount of wall charge movement due to write discharge increases. Under the condition of ΔQ of 3.5 pC or less, since the writing failure occurs, the wall charge amount is small and flickering occurs. Increasing Vdata increases the discharge probability, and the write failure decreases, so that the wall charge amount increases and normal driving is performed.

  When α is in the range up to about 6 V / μs, increasing α increases the slope of the plot of ΔQ with respect to Vdata, and normal driving is possible even at lower Vdata. In the range of α, the light emission due to the discharge of the initialization pulse is much weaker than the sustain discharge, so the contrast is not lowered. However, when α is increased to 10 V / μs or more, the contrast is significantly lowered.

  This is because if α at the rising portion is too large, a strong discharge occurs at the rising portion of the initialization pulse, and an excessive wall voltage is accumulated, so that a discharge occurs at the falling portion, so-called self-erasing discharge occurs, Since the light emission by the initialization pulse becomes strong, the contrast is lowered. Further, under such conditions, the wall voltage cannot be controlled by uniform initialization, and a write discharge failure occurs in the subsequent write period. Therefore, it can be seen that the optimum value of α is 1 ≦ α ≦ 9 [V / μs].

  As apparent from this, the wall voltage at the end of the initialization period is optimally controlled by the driving method of the PDP according to the third embodiment, and the flickering is performed without impairing the contrast by suppressing the writing discharge failure. Very good image quality can be realized in that image quality degradation such as roughness is suppressed.

  In the third embodiment, the rising edge of the initialization pulse is a five-step stepped pulse waveform, but it goes without saying that an excellent image quality can be realized even with a multi-stepped pulse having six or more steps.

  In the third embodiment, the rising edge of the initialization pulse is a multistage stepped pulse waveform. However, it goes without saying that excellent image quality can be realized not only by the rising edge but also by using a multistage stepped pulse as the falling edge.

(Embodiment 4)
FIG. 11 shows a timing chart of drive waveforms according to the fourth embodiment of the present invention.

  The difference from the conventional method is that a stepped waveform that drops the voltage in two steps at the fall of the pulse is used as the write pulse.

  FIG. 12 shows the relationship between the write pulse width PW and ΔQ at various write pulse voltages Vdata when a conventional write pulse using a simple rectangular wave is used.

  At Vdata = 60V, the writing discharge is almost normally performed at a pulse width of PW of 2.0 μs or more, but the display image quality is slightly flickered.

  By raising Vdata, the write discharge is normally performed to a region where PW is shorter, and even when PW is shortened to 1.0 μs at Vdata = 100 V, the write discharge is normally performed. For example, when the number of scanning lines increases due to high definition necessary for realizing full-spec high-definition or the like, it is possible to increase the speed of the writing pulse which is indispensable.

  However, the data driver generally used in the PDP has a relationship in which the slew rate of the voltage at the rise of the pulse and the withstand voltage are in conflict with each other, and a drive circuit necessary for generating such a high-voltage pulse having a fast rise. It was difficult to manufacture the material and had a big problem that the cost was very increased.

  Table 1 shows a comparison of the average discharge delay time during the write discharge when the conventional drive waveform and the drive waveform of the fourth embodiment are used.

  It can be seen that the discharge delay time is reduced by using a stepped waveform that drops the voltage in two steps at the fall of the pulse as the write pulse.

  This is because a high voltage is applied to the discharge cell only at the rising edge of the pulse to complete the discharge between the data and scan electrodes in a short time, and the discharge priming at the rising edge of the pulse causes the discharge between the sustain and scan electrodes. This is probably because the discharge delay of the generated discharge has decreased.

  As is clear from this, by using the drive waveform of the fourth embodiment, it becomes possible to improve the discharge delay and speed up the drive pulse.

  As a drive circuit for generating these stepped waveforms, the output voltage waveform of the arbitrary waveform generator is amplified by a high-speed and high-voltage amplifier and applied to the discharge cell in the fourth embodiment, but this is not limitative. Instead of adding two types of pulse voltage generators with diodes, and superimposing the second stage pulse voltage on the first stage pulse voltage to form a stepped waveform, the pulse at each stage Needless to say, it is possible to use a driver IC having a withstand voltage of about 100 V as the voltage generating circuit, and to realize a high-definition and excellent image quality PDP at low cost.

(Embodiment 5)... Staircase waveform and image quality improvement at rising edge of write pulse FIG. 13 is a timing chart of drive waveforms according to Embodiment 5 of the present invention.

  The difference from the conventional method is that a staircase waveform that increases the voltage in two steps at the rising edge of the pulse is used as the write pulse.

  FIG. 14A shows a light emission peak due to a write discharge when driving using a conventional drive waveform, and FIG. 14B shows a light emission peak due to a sustain discharge. As is clear from this figure, the light emission by the write discharge is larger than the light emission by the first sustain pulse during the sustain period, and has the same light emission peak area as the second and subsequent sustain discharges. It can be seen that light is emitted in size. For this reason, when displaying a halftone, when a low-bit subfield with a small number of pulses in the sustain period is selected for low gradation display, the luminance of the light emission by the write discharge is the light emission of these sustain discharges. Therefore, the gray scale at the time of halftone display becomes discontinuous, and when gray scale display is performed using a ramp waveform as a video signal, the display image quality at low gradation is deteriorated. When the voltage of the write pulse applied to the data electrode is reduced to suppress this, the discharge delay of the write discharge increases, causing an address failure.

  Table 2 shows a comparison result of image quality when the conventional waveform and the drive waveform of the fifth embodiment are used.

  This is because writing using a stepped waveform with two rising pulses is used as a writing pulse, light emission due to writing discharge is suppressed, and writing that is added to sustain discharge light emission when a low-bit subfield is selected. This is because the luminance of light emission due to discharge is reduced.

  As is clear from this, by using the drive waveform of the fifth embodiment, gray scale display at the time of halftone display can be improved without lowering the write pulse voltage, address failure, flicker, etc. Therefore, it is possible to realize a PDP having an image quality that is excellent in gradation reproducibility without any image quality degradation.

  In the fifth embodiment, the output voltage waveform of the arbitrary waveform generator is amplified by a high-speed high-voltage amplifier and applied to the discharge cell as a drive circuit for generating these stepped waveforms. However, the present invention is not limited to this. Instead of adding two types of pulse voltage generation circuits, the stepped waveform is formed by superimposing the second stage pulse voltage on the first stage pulse voltage to generate a pulse voltage at each stage. Needless to say, the circuit can use a driver IC having a withstand voltage of about 100 V, and can realize a high-definition and excellent image quality PDP at low cost.

(Embodiment 6)
FIG. 15 is a timing chart of drive waveforms according to the sixth embodiment of the present invention.

  The difference from the conventional driving method is that driving is performed by lowering the sustain pulse in two steps. FIGS. 16A and 16B show a voltage waveform V and a light emission peak waveform B of a sustain pulse when driven using a conventional simple rectangular wave.

  In the case of driving using a conventional simple rectangular wave, the brightness increases as the drive voltage is increased. However, if the discharge at the rising edge of the pulse becomes too strong, the pulse waveform as shown in FIG. A weak discharge occurs even at the falling edge, causing abnormal operation. This is a phenomenon generally called self-erasing discharge, and the wall voltage accumulated in the discharge cell due to the discharge at the rising portion becomes too high. This is because discharge occurs in the opposite direction. When this self-erase discharge occurs, the wall voltage accumulated by the discharge at the rising portion is lowered, so that when the discharge is performed by the next reverse pulse voltage, the effective voltage applied to the discharge gas in the cell The voltage drops and the discharge becomes unstable, causing abnormal operation.

  FIG. 17 shows an example of the voltage waveform V and the light emission peak waveform B of the sustain pulse when driven using the drive waveform in the present invention. Although the maximum value of the pulse voltage applied to the discharge cell is the same as that in FIG. 16B, no light emission is observed at the falling edge of the pulse, and it can be seen that no self-erasing discharge occurs. . This is because the sudden voltage change is mitigated by reducing the falling of the sustain pulse in two steps, and the self-erasing discharge is suppressed. At this time, the maximum value of the pulse voltage was such that the self-erase discharge did not occur up to the applied voltage at the start of discharge, that is, the discharge start voltage Vf + 150V.

  In Table 3, when the conventional simple rectangular wave is used for driving and when the driving waveform of the sixth embodiment is used for driving, the maximum value of the pulse voltage, the relative luminance, and whether or not self-erasing discharge occurs A comparison of is shown.

  As described above, the falling of the sustain pulse is lowered in two steps, so that the rapid voltage change is alleviated to suppress the self-erasing discharge, and the erasing of the wall charge in the discharge cell due to the self-erasing discharge is suppressed. Therefore, the wall voltage in the discharge cell also increases, and the amount of mobile charge due to discharge increases, so that the luminance increases.

  As is clear from this, by using the PDP driving method according to the sixth embodiment, the luminance is significantly increased by using at least two stepped voltage waveforms as sustain pulses for maintaining light emission, and It is possible to suppress the occurrence of self-erasing discharge, enable stable operation, and realize a PDP with high luminance and excellent image quality.

(Embodiment 7)
FIG. 18 is a timing chart of drive waveforms according to the seventh embodiment of the present invention.

  The difference from the conventional driving method is that driving is performed by changing the rising and falling edges of the sustain pulse in two stages. FIG. 19 shows a schematic diagram of a VQ Lissajous figure when driven using a conventional simple rectangular wave. In the case of driving using a conventional simple rectangular wave, the brightness increases when the drive voltage is increased, but the discharge current increases in the same way, so that the power consumption increases and the Lissajous loop remains similar. Enlarge (a → b). For this reason, the light emission rate of the PDP is hardly improved.

  FIG. 20 shows an example of a VQ Lissajous figure in the case of driving using the drive waveform in the seventh embodiment.

  It can be seen that the loop of the VQ Lissajous figure changes from a parallelogram to a distorted rhombus by making the sustain pulse into a two-step staircase waveform. At this time, in the range where the voltage of the first stage is the discharge start voltage Vf−20V or more and Vf + 30V or less, and the voltage holding time of the first stage from the rising edge of the first stage pulse to the rising edge of the second stage pulse, In the range of the discharge formation delay time Tdf−0.2 μs to Tdf + 0.2 μs, a rhombic loop distorted from the parallelogram was obtained.

  Table 4 shows a comparison of relative luminance, relative power consumption, and relative luminous efficiency when driving using a conventional simple rectangular wave and when driving using the driving waveform of the seventh embodiment.

  Although the sustain pulse has a two-step staircase waveform, the increase in power consumption is suppressed to about 15% and the light emission efficiency is improved by about 13%, although the luminance is increased by about 30%. This is because the sustain pulse has a two-step staircase waveform, so that the increase in the applied voltage applied to the discharge cell and the phase of the discharge current are aligned, so that invalid power is suppressed. The increase rate of electric power was suppressed and the discharge efficiency was improved.

  As is clear from this, the driving method of the PDP of the seventh embodiment makes it possible to significantly increase the luminance and suppress the increase in power consumption, and to achieve a PDP with high luminance and excellent image quality. It is possible to realize.

  In the seventh embodiment, the rising and falling edges of the sustain pulse are stepped pulse waveforms, but it goes without saying that excellent image quality can also be realized when only the rising edge is a stepped pulse waveform.

(Embodiment 8)
FIG. 21 shows a timing chart of drive waveforms according to the eighth embodiment of the present invention.

  The difference from the seventh embodiment is that the rising and falling edges of the sustain pulse are changed in two stages, and the voltage at the first stage of the rise is set as the cell discharge start voltage Vf, between the first stage and the second stage. The voltage change was changed sinally so as to have a maximum slope at the peak of the discharge current, and the voltage was reduced to the minimum discharge sustaining voltage Vs in the simple rectangular wave drive promptly and cos function with the stop of the discharge current. It is to drive using a waveform.

  FIG. 22 shows time-axis traces of the interelectrode voltage V and the charge amount Q, the charge amount differential value dQ / dt, and the emission peak waveform B of the discharge cell when driven using the drive waveform in the eighth embodiment. The rising and falling edges of the sustain pulse are changed in two stages, and the voltage change between the first and second stages is changed in a trigonometric function, so that the first stage discharge starts at the rising edge of the pulse. The voltage rises to the second stage after the discharge current begins to flow due to the voltage, and the phase of the voltage rise to the second stage is delayed from the discharge current, reaching the maximum slope of the voltage rise near the peak of the discharge current. I understand that. It can also be seen that a high voltage is applied to the discharge cell only during the period in which light emission is performed by discharging by decreasing the voltage to Vs as the discharge current is stopped.

  FIG. 23 shows an example of a VQ Lissajous figure in the case of driving using the drive waveform in the eighth embodiment. The loop of the VQ Lissajous figure changes to a distorted rhombus with arcs on both sides and is elongated horizontally. The phase of the voltage change between the first and second stages is determined by the discharge current. By delaying, it can be seen that even after the discharge is started in the cell, an overvoltage is further applied from the power source, and power is effectively injected into the plasma in the discharge cell.

  Table 5 shows a comparison of relative luminance, relative power consumption, and relative light emission efficiency when driven using a conventional simple rectangular wave and when driven using the drive waveform of the eighth embodiment.

  By changing the voltage immediately after the discharge current is stopped by changing the maximum slope of the voltage increase from the first stage to the second stage at the peak of the discharge current, the power consumption is reduced. It can be seen that the increase is relatively small and the luminous efficiency is improved by about 30%.

  As is clear from this, the driving method of the PDP of the eighth embodiment makes it possible to significantly increase the luminance and suppress the increase in power consumption, and to achieve a high-brightness and excellent image quality PDP. It is possible to realize.

  In the eighth embodiment, the trigonometric function is used as the continuous function of the rising voltage waveform at the second stage, but the same effect can be obtained by using other continuous functions such as an exponential function and a Gaussian function. It goes without saying that it is obtained.

(Embodiment 9)
FIG. 24 is a timing chart of drive waveforms according to the ninth embodiment of the present invention.

  The difference from the conventional driving method is that the rising edge of the sustain pulse is driven using a waveform in which the voltage increase rate is inclined in a range where the driving is not affected. By applying a slope to the rate of voltage rise at the rising edge of the pulse, the applied voltage at the maximum discharge current can be made higher than the applied voltage at the start of discharge.

  FIG. 25 shows time axis traces of the interelectrode voltage V and the charge amount Q, the charge amount differential value dQ / dt, and the emission peak waveform B of the discharge cell when driven using the drive waveform in the ninth embodiment.

  The drive applied to the discharge cell at the time when the discharge current and the emission peak show the maximum than the drive voltage applied to the discharge cell at the start of discharge by making the rising edge of the sustain pulse into a waveform with a slope. It can be seen that the voltage is high.

  FIG. 26 shows an example of a VQ Lissajous figure in the case of driving using the driving waveform in the ninth embodiment. By using the drive waveform in the present invention, both sides of the loop of the VQ Lissajous figure are changed to a rhombus with an inclination, and the discharge start voltage is lower than the discharge end voltage at which the charge has finished moving. It can be seen that the area inside is decreasing.

  Table 6 shows a comparison of relative luminance, relative power consumption, and relative luminous efficiency when driving using a conventional simple rectangular wave and when driving using the driving waveform of the ninth embodiment.

  Although the decrease in luminance is slight by using the drive waveform of the ninth embodiment for the sustain pulse, the light emission efficiency is improved by about 7% by reducing the power consumption by about 13%.

  As is clear from this, the PDP driving method according to the ninth embodiment makes it possible to keep power consumption low without impairing luminance, and to realize a PDP having excellent image quality with low power consumption. It is.

(Embodiment 10)... Stepped waveform for sustain pulse, probability of first occurrence FIG. 27 is a timing chart of drive waveforms in Embodiment 10 of the present invention.

  The difference from the prior art is that after the rising and falling edges of the first sustain pulse are changed in two stages in the sustain period, the first stage voltage is raised between the minimum discharge sustain voltages Vs in the simple rectangular wave drive. The voltage is increased to the peak voltage of the second stage, and is driven by using the waveform in which the voltage is decreased to Vs of the first stage as soon as the discharge is stopped.

  In general, there is a time lag between the application of a pulse voltage and the occurrence of discharge, and this discharge delay has a strong correlation with the applied voltage. The higher the voltage, the shorter the discharge delay and the narrower the distribution. It has been known. In the PDP, the gas voltage Vgas applied to the discharge gas in the discharge cell depends on the wall voltage accumulated in the dielectric covering the electrode and the drive voltage supplied from the power supply outside the cell. The discharge delay and its distribution are strongly influenced by the wall voltage.

  For this reason, the discharge generated by the first sustain pulse applied to the discharge cell at the beginning of the sustain period is strongly influenced by the wall voltage generated as a result of the write discharge prior to that, and is very unstable. This is one of the major causes of image quality degradation due to screen flicker.

  In the driving method of the tenth embodiment, the first discharge delay of the sustain pulse and its distribution are improved by making the first waveform of the sustain pulse into a two-step staircase waveform.

  28A and 28B show time axis traces of the interelectrode voltage Vscn-sus and the light emission peak waveform B of the discharge cell when driven using the conventional driving waveform and the driving waveform of the present invention.

  In the measurement of the voltage waveform and the peak emission waveform, the average of 500 scans was taken using a digital oscilloscope, and noise was removed. From this figure, by changing the first waveform of the sustain pulse in two steps, the time from the rising edge of the pulse until the light emission due to the discharge, that is, the discharge delay time decreases, and the light emission due to the discharge becomes stronger. I understand that.

  Table 7 shows the average discharge delay time of the discharge generated by the first sustain pulse in the case of driving using the conventional simple rectangular wave and the case of driving using the driving waveform of the tenth embodiment. Comparison of brightness and image quality is shown.

  By using a staircase waveform for the first sustain pulse in the sustain period, the first discharge probability is improved and the discharge delay is reduced, so that the subsequent discharge due to the sustain pulse is stabilized and image quality degradation such as flickering is reduced. The temporal average brightness is also improved by the improvement.

  As is clear from this, it is possible to realize a PDP having high luminance and excellent image quality by the PDP driving method of the tenth embodiment.

(Embodiment 11)
FIG. 29 shows a drive waveform timing chart according to Embodiment 11 of the present invention.

  The difference from the prior art is that the rising edge of the erase pulse is raised in two steps.

  FIG. 30 shows the contrast with respect to the ratio tp / tw of the flat portion width of the first stage to the pulse width and the ratio V1 / Ve of the voltage of the first stage to the maximum voltage of the pulse in a stepped waveform in which the rising edge of the erase pulse is two steps. Shows the relationship. The contrast is high within the shaded area and is not very practical outside this area. This is because, in the prior art, a voltage was applied in one step and a discharge was generated by a sudden voltage change, so that the entire surface was emitted by an originally unnecessary erase pulse, and the discharge cells in the panel varied. In contrast, the wall charge amount remaining after application of the erase pulse varies, and erroneous discharge is induced in the next drive sequence, whereas in the eleventh embodiment, weak discharge is performed by a two-step staircase waveform, Eliminates wall charges uniformly and suppresses overall light emission.

  As is clear from this, the PDP driving method according to the eleventh embodiment suppresses erroneous discharge due to residual wall charges after one driving sequence and suppresses light emission due to an erasing pulse, thereby significantly improving contrast. A very good image quality is achieved.

  In the eleventh embodiment, the rising edge of the erase pulse has a two-stage stepped pulse waveform, but it goes without saying that an excellent image quality can be realized even with a multi-stage stepped pulse having three or more stages.

  It goes without saying that excellent image quality can also be realized when the voltage of the first stage of the stepped pulse voltage waveform is a stepped pulse having a discharge start voltage Vf−50V or more and Vf + 30V or less.

  Needless to say, excellent image quality can be realized even when the maximum voltage Vsmax of the stepped pulse voltage waveform is a stepped pulse having a discharge start voltage Vf or more and Vf + 100 V or less.

(Embodiment 12)-Erase pulse fall in two stages, shortening of erase period FIG. 31 shows a timing chart of drive waveforms in Embodiment 12 of the present invention.

  The difference from the prior art is that the trailing edge of the erase pulse is lowered in two steps.

  Table 8 shows a comparison of the discharge delay time of the erasing discharge, the pulse width, and the quality of the erasing operation in the conventional erasing pulse waveform and the stepped waveform in which the erasing pulse falls in two steps.

  Since the discharge pulse is improved by making the erasing pulse fall into a two-step staircase waveform, and the driving circuit for generating the pulse voltages of the first and second stages does not require a high breakdown voltage. This makes it possible to use a power MOSFET with a fast pulse falling slew rate, which makes it possible to further shorten the erase pulse width, thereby shortening the erase period of each subfield, which is caused by this. Increase the picture quality by allocating the surplus time to the increase of the sustain period to increase the brightness by increasing the writing period by increasing the number of scanning lines due to high definition or increasing the number of sustain pulses during the sustain period, or High brightness can be achieved.

  As is clear from this fact, the PDP driving method according to the twelfth embodiment is extremely effective in that high definition or high luminance is realized by using the surplus time generated by shortening the erase pulse width. PDP with excellent image quality is realized.

  In the twelfth embodiment, the falling edge of the erase pulse has a two-stage stepped pulse waveform. Needless to say, an excellent image quality can be realized even with a multistage stepped pulse having three or more stages.

  Needless to say, excellent image quality can be realized even when the maximum voltage Vsmax of the stepped pulse voltage waveform is a stepped pulse having a discharge start voltage Vf or more and Vf + 100 V or less.

(Embodiment 13) ... High gas pressure The difference between Embodiments 13 and 12 in Embodiment 13 is that a quaternary mixed gas of He-Ne-Xe-Ar is used as a discharge gas, which is higher than conventional 760. ˜4000 Torr sealed.

  In a PDP having a configuration similar to the conventional one (distance between electrodes d = 40 μm), He (50%)-Ne (48%)-Xe (2%), He (50%)-Ne (48%)-Xe (2 %)-Ar (0.1%), He (30%)-Ne (68%)-Xe (2%), He (30%)-Ne (67.9%)-Xe (2%)-Ar PDPs using various composition gases (0.1%) as discharge gas were prepared, and the relationship between the Pd product and the discharge start voltage was examined in each of the prepared PDPs. FIG. 32 is a graph showing the results.

  The lower part of FIG. 32 shows the brightness (discharge voltage 250 V) of the PDP using each composition gas.

  In particular, when a gas of He (30%)-Ne (67.9%)-Xe (2%)-Ar (0.1%) is used, the luminance is relatively good and the Pd product = 6 (Torr). It can be seen that even under the condition (cm) (interelectrode distance d = 60 μm and sealed pressure 1000 Torr), the discharge start voltage can be put into a practically usable discharge start voltage region (220 V or less).

  In this gas composition, the discharge start voltage has a minimum value in the vicinity of the Pd product = 4. Accordingly, the Pd product = 4 (for example, when the sealing pressure is 2000 Torr, the interelectrode distance d = 20 μm) is set. It can be seen that this is preferable.

  These absolute values (especially the discharge start voltage) change by changing the Xe amount, but the relative relationship hardly changes.

  However, when an image is actually displayed using a conventional driving waveform, discharge must be performed between one of the electrode groups 19a and 19b on the front plate and the data electrode group 14 on the back plate during the write operation. If the distance between the electrode group on the front plate and the electrode group on the back plate is shortened to about 20 μm, the conventional PDP discharge cell structure in which the phosphor layer is applied to the inner side of the barrier rib on the back plate can provide sufficient discharge. There was a big problem that space could not be secured.

  In the thirteenth embodiment, as shown in FIG. 33, driving is performed using a stepped waveform that changes the pulse voltage waveform applied to the discharge cells in two stages during the writing period and the sustain period.

  In Table 9, when a PDP having a conventional configuration with a partition wall height of 60 μm and a sealing pressure of 2000 Torr is actually displayed using the conventional drive waveform and the stepped drive waveform of the thirteenth embodiment. The evaluation results of brightness, efficiency and image quality are shown.

  In spite of the fact that the height of the partition wall and the sealing pressure are the same, in the conventional driving waveform, an address failure occurs and the image quality is hardly improved even when the initialization pulse voltage and the write pulse voltage are increased. This is because the distance between the electrodes of the front plate and the back plate is large, so that the discharge start voltage rises and the wall charge amount is not sufficiently accumulated.

  On the other hand, in the driving waveform of the thirteenth embodiment, no defective address was observed, and a good image display was possible. This is because write discharge is performed without imposing a burden on the data driver circuit even in a panel having a discharge start voltage higher than normal by using a stepped waveform for the write pulse applied to the data electrode used in the write operation. By improving the discharge delay, the write discharge is completed within the time of the pulse width of the write pulse, the wall charge amount during the write discharge is increased, and the sustain pulse applied to the discharge cell during the sustain period is also applied. This is because the discharge delay of the sustain discharge is improved by applying the stepped waveform, and the image quality deterioration such as flicker is improved by completing the sustain discharge within the pulse width of the sustain pulse. In addition, the efficiency was about 1.5 times as high as that of the conventional configuration in which Ne (95%)-Xe (5%) mixed gas was sealed at 500 Torr.

  As described above, the PDP according to the thirteenth embodiment uses a stepped waveform that changes the pulse voltage waveform applied to the discharge cell in two stages during the writing period and the sustain period, so that the discharge gas sealing pressure is high. Can realize a high-quality, high-efficiency PDP with no address failure.

  As described above, according to the present invention, the pulse voltage applied to the discharge cell uses a stepped pulse waveform having at least two steps, thereby eliminating the need for applying the priming pulse preceding the writing period and the erasing pulse after the sustain period. Suppresses light emission caused by excessive discharge, improves contrast, and reduces the discharge delay of the write discharge during the write period, thereby significantly improving the degradation of image quality due to write failure and improving the light emission efficiency of the sustain discharge during the sustain period As a result, it is possible to obtain a remarkable effect of increasing the luminance and realizing a high-definition and very high-quality PDP.

Timing chart of driving method of plasma display panel in Embodiment 1 of the present invention Electrode matrix diagram of conventional plasma display panel Timing chart of conventional plasma display panel driving method Schematic of a subfield of a conventional plasma display panel driving method Configuration diagram showing a conventional plasma display panel The figure which shows the relationship of the contrast with respect to tp / tw and V1 / Vst in Embodiment 1 of this invention. Timing chart of driving method of plasma display panel in embodiment 2 of the present invention The figure which shows the relationship of the contrast with respect to tp / tw and V1 / Vst in Embodiment 2 of this invention. Timing chart of driving method of plasma display panel in Embodiment 3 of the present invention The figure which shows an example of the dependence of (DELTA) Q with respect to Vdata at the time of driving with various average change speeds using the drive method of the plasma display panel in Embodiment 3 of this invention. Timing chart of driving waveform of plasma display panel in Embodiment 4 of the present invention The figure which shows the relationship between write pulse width PW and (DELTA) Q in the various write pulse voltage Vdata at the time of using the conventional rectangular wave-like write pulse. Timing chart of driving waveform of plasma display panel according to embodiment 5 of the present invention (A) The figure which shows the time-axis trace of the light emission peak waveform B by the drive voltage waveform V and the write discharge at the time of driving using the conventional drive waveform, (b) It driven using the conventional drive waveform Of time axis trace of light emission peak waveform B due to drive voltage waveform V and sustain discharge at the time Timing chart of driving waveform of plasma display panel in Embodiment 6 of the present invention (A) FIGS. (B) and (a) showing the time-axis traces of the voltage waveform V of the sustain pulse and the light emission peak waveform B when driven using a conventional simple rectangular wave. FIG. Figure The figure which shows the time-axis trace of the voltage waveform V of the sustain pulse at the time of driving using the drive waveform in Embodiment 6 of this invention, and the light emission peak waveform B Timing chart of driving waveform of plasma display panel in embodiment 7 of the present invention Schematic diagram of VQ Lissajous figure when driven using conventional simple rectangular wave The figure which shows an example of the VQ Lissajous figure at the time of driving using the drive waveform in Embodiment 7 of this invention Timing chart of driving waveform of plasma display panel according to embodiment 8 of the present invention The figure which shows the time-axis trace of the voltage V between electrodes of the discharge cell and the charge amount Q at the time of driving using the drive waveform in Embodiment 8 of this invention, the differential value dQ / dt of charge amount, and the light emission peak waveform B The figure which shows an example of the VQ Lissajous figure at the time of driving using the drive waveform in Embodiment 8 of this invention. Timing chart of driving waveform of plasma display panel according to embodiment 9 of the present invention The figure which shows the time-axis trace of the voltage V between the electrodes of the discharge cell and charge amount Q at the time of driving using the drive waveform in Embodiment 9 of this invention, the differential value dQ / dt of charge amount, and the light emission peak waveform B The figure which shows an example of the VQ Lissajous figure at the time of driving using the drive waveform in Embodiment 9 of this invention Timing chart of driving waveform of plasma display panel according to the tenth embodiment of the present invention FIGS. 4A and 4B are diagrams showing time axis traces of a discharge cell interelectrode voltage Vscn-sus and a light emission peak waveform B when driving using a conventional driving waveform and a driving waveform according to the present invention. Timing chart of driving waveform of plasma display panel according to embodiment 11 of the present invention The figure which shows the relationship of the contrast with respect to tp / tw and V1 / Ve in Embodiment 11 of this invention. Timing chart of driving waveform of plasma display panel according to embodiment 12 of the present invention The figure which shows the relationship between Pd product and discharge start voltage in various discharge gas composition Timing chart of driving waveform of plasma display panel according to embodiment 13 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Front substrate 12 Back substrate 13 Insulator layer 14 Data electrode group 15 Partition 16 Phosphor 17 Dielectric glass layer 18 Protective layer 19a Electrode group 19b Electrode group

Claims (4)

A method of driving a plasma display panel in which a plurality of discharge cells having first and second electrode pairs are formed,
The driving method is:
It has an initialization period for performing initialization,
During the initialization period, the average value of the voltage change rate when rising is 1 V / μs or more and 9 V / μs or less, and
A method of driving a plasma display panel, wherein a pulse having a waveform having a voltage change rate when starting to fall is greater than an average value of the voltage change rate when rising is applied to the discharge cells. A method of driving a plasma display panel in which a plurality of discharge cells having first and second electrode pairs are formed,
The driving method is:
An initialization period for performing initialization, and a writing period for performing writing based on input image data,
During the initialization period, the average value of the voltage change rate when rising is 1 V / μs or more and 9 V / μs or less, and the voltage change rate when starting to decrease is the voltage change rate when rising Applying a pulse having a waveform larger than an average value to the discharge cell through the first electrode;
A method for driving a plasma display panel, wherein a writing pulse is applied to the discharge cell through the first electrode during the writing period. A first substrate on which a plurality of pairs of first and second electrodes are arranged and a second substrate on which a plurality of third electrodes are arranged are arranged at an interval, and the first substrate is disposed between the first and second substrates. A plasma display panel in which a plurality of discharge cells having second and third electrodes are formed;
An image display device comprising an initialization period for performing initialization in one frame, and a driving circuit for applying a pulse to the discharge cells to drive the plasma display panel,
The drive circuit is
During the initialization period, the average value of the voltage change rate when rising is 1 V / μs or more and 9 V / μs or less, and
An image display device configured to apply, to the discharge cell, a pulse having a waveform in which a voltage change rate when starting to fall is larger than an average value of the voltage change rates when rising. A first substrate on which a plurality of pairs of first and second electrodes are arranged and a second substrate on which a plurality of third electrodes are arranged are arranged at an interval, and the first substrate is disposed between the first and second substrates. A plasma display panel in which a plurality of discharge cells having second and third electrodes are formed;
A driving circuit for driving the plasma display panel by applying a pulse to the discharge cells, and including an initialization period for performing initialization in one frame and a writing period for performing writing based on input image data; An image display device comprising:
The drive circuit is
During the initialization period, the average value of the voltage change rate when it rises is 1 V / μs or more and 9 V / μs or less, and the voltage change rate when it starts to fall is the voltage change rate when it rises Applying a pulse having a waveform larger than an average value to the discharge cell through the first electrode;
An image display device configured to apply a write pulse to the discharge cell through the first electrode during the write period.

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