JP5092276B2 - Plasma display panel driving method and plasma display device - Google Patents

Description

  The present invention relates to a driving method of a plasma display panel and a plasma display device used for a wall-mounted television or a large monitor.

  A typical AC surface discharge type panel as a plasma display panel (hereinafter abbreviated as “panel”) has a large number of discharge cells formed between a front plate and a back plate arranged to face each other. In the front plate, a plurality of display electrode pairs each consisting of a pair of scan electrodes and sustain electrodes are formed in parallel with each other on the front glass substrate, and a dielectric layer and a protective layer are formed so as to cover the display electrode pairs. Yes. The back plate has a plurality of parallel data electrodes on the back glass substrate, a dielectric layer so as to cover them, and a plurality of barrier ribs in parallel with the data electrodes formed on the back glass substrate. A phosphor layer is formed on the side walls of the barrier ribs. Then, the front plate and the back plate are arranged opposite to each other so that the display electrode pair and the data electrode are three-dimensionally crossed and sealed, and a discharge gas containing, for example, 5% xenon is enclosed in the internal discharge space. Has been. Here, a discharge cell is formed at a portion where the display electrode pair and the data electrode face each other. In the panel having such a configuration, ultraviolet light is generated by gas discharge in each discharge cell, and phosphors of red, green, and blue colors are excited and emitted by the ultraviolet light to perform color display.

  As a method of driving the panel, a subfield method, that is, a method of performing gradation display by combining subfields to emit light after dividing one field period into a plurality of subfields. Each subfield has an initialization period, an address period, and a sustain period. In the initialization period, an initialization discharge is generated, and wall charges necessary for the subsequent address operation are formed on each electrode. In the address period, address discharge is selectively generated in the discharge cells to be displayed to form wall charges. In the sustain period, a sustain pulse is alternately applied to the display electrode pair composed of the scan electrode and the sustain electrode, and a sustain discharge is generated in the discharge cell in which the address discharge is generated, and the phosphor layer of the corresponding discharge cell is caused to emit light. The image is displayed.

  As a circuit for applying a sustain pulse to a display electrode pair, a so-called power recovery circuit that can reduce power consumption is generally used (see, for example, Patent Document 1). Patent Document 1 focuses on the fact that each of the display electrode pairs is a capacitive load having an interelectrode capacitance of the display electrode pair, and uses a resonance circuit including an inductor as a constituent element. Has been disclosed, and a power recovery circuit is disclosed in which the electric charge stored in the interelectrode capacitance is recovered in a power recovery capacitor, and the recovered charge is reused for driving the display electrode pair.

  On the other hand, with the recent increase in screen size and definition of panels, various efforts have been made to improve the light emission efficiency and brightness of the panel. For example, studies are being made to significantly increase the luminous efficiency by increasing the xenon partial pressure. However, when the xenon partial pressure is increased, the variation in the timing at which discharge occurs increases, and the emission intensity varies from discharge cell to discharge cell, resulting in non-uniform display brightness. In order to improve this non-uniform brightness, a driving method is disclosed in which, for example, a sustain pulse with a steep rise is inserted at a rate of once every several times so that the timing of the sustain discharge is aligned and the display brightness is made uniform. (For example, refer to Patent Document 2).

Further, when the xenon partial pressure is increased, when a high-luminance image is displayed after a still image or the like is displayed for a long time, the still image may be recognized as an afterimage, which may impair image display quality. In order to reduce such an afterimage phenomenon, a method of suppressing a decrease in image display quality by moving a display position of an image in which an afterimage is likely to occur is disclosed (for example, see Patent Document 3).
Japanese Examined Patent Publication No. 7-109542 JP-A-2005-338120 JP-A-8-248934

  However, according to the method described in Patent Document 3, the degree of recognition of the afterimage is reduced to some extent, but the afterimage phenomenon itself is not reduced. In addition, since image processing such as moving the display position of the image is used in combination, the image may not be displayed faithfully.

  The panel driving method and the plasma display apparatus of the present invention have been made in view of these problems, and reduce the afterimage phenomenon itself while performing faithful image display, and make the display luminance of each discharge cell uniform. An object of the present invention is to provide a panel driving method and a plasma display device.

The present invention relates to a method for driving a panel having a plurality of discharge cells each having a display electrode pair composed of a scan electrode and a sustain electrode, wherein an initialization period for generating an initializing discharge in one discharge cell, and a discharge The sustain period is composed of a plurality of subfields having an address period for generating an address discharge in the cell and a sustain period for generating a sustain discharge in a discharge cell in which an address discharge is generated by applying a sustain pulse to the display electrode pair. And generating a sustain discharge using a reference sustain pulse and a specific pulse whose rise is more gradual than the reference sustain pulse, and a specific pulse that is continuous twice or more and a reference pulse that is a reference that is continuous twice or more DOO alternately caused to generate, based on the lighting rate for each sub-field, and configured to control the number of consecutive occurrences of a particular pulse and the reference pulse, the point If the rate is lower than a predetermined value, characterized by many to Rukoto successive occurrence count than when the lighting rate is high. By this method, it is possible to provide a panel driving method capable of reducing the afterimage phenomenon itself while performing faithful image display and making the display luminance of each discharge cell uniform.

In addition, the plasma display device of the present invention includes a panel including a plurality of discharge cells each having a display electrode pair including a scan electrode and a sustain electrode, and a plurality of fields each having an initialization period, an address period, and a sustain period. A sustain pulse generating circuit that generates a sustain discharge in the discharge cell by alternately applying a sustain pulse to the display electrode pair in the sustain period during the sustain period, and the sustain pulse generating circuit is provided between the electrodes of the display electrode pair. The power recovery unit that resonates the capacitance and the power recovery inductor to apply a voltage to the display electrode pair, and the clamp unit that clamps the display electrode pair to the power supply voltage or the ground potential, and the sustain pulse rise time Is a reference pulse whose capacitance is less than half of the resonance period between the capacitance between the electrodes and the power recovery inductor, and a specific pulse whose rise time is longer than the reference pulse. DOO well as configured to generate the sustain discharge was used to generate a reference pulse particular pulse and consecutive two or more times consecutive two or more times alternately, based on the lighting rate for each sub-field, particular pulse and reference It is configured to control the number of continuous generations of pulses, and when the lighting rate is lower than a predetermined value, the number of continuous generations is increased as compared with the case where the lighting rate is high . With this configuration, it is possible to provide a plasma display device capable of reducing the afterimage phenomenon itself while performing faithful image display and making the display luminance of each discharge cell uniform.

  Further, in the plasma display apparatus of the present invention, the sustain pulse generation circuit may be configured to alternately generate a specific pulse that is continued four times or more and a reference pulse that is continuous four times or more.

  According to the present invention, it is possible to provide a panel driving method and a plasma display device capable of reducing the afterimage phenomenon itself while performing faithful image display and making the display luminance of each discharge cell uniform. .

  Hereinafter, a plasma display device according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment)
FIG. 1 is an exploded perspective view showing a structure of panel 10 according to the embodiment of the present invention. On the glass front plate 21, a plurality of display electrode pairs 28 made up of the scan electrodes 22 and the sustain electrodes 23 are formed. A dielectric layer 24 is formed so as to cover the scan electrode 22 and the sustain electrode 23, and a protective layer 25 is formed on the dielectric layer 24. A plurality of data electrodes 32 are formed on the back plate 31, a dielectric layer 33 is formed so as to cover the data electrodes 32, and a grid-like partition wall 34 is formed thereon. A phosphor layer 35 that emits red, green, and blue light is provided on the side surface of the partition wall 34 and on the dielectric layer 33.

  The front plate 21 and the back plate 31 are arranged to face each other so that the display electrode pair 28 and the data electrode 32 intersect each other with a minute discharge space interposed therebetween, and the outer periphery thereof is sealed with a sealing material such as glass frit. Has been. In the discharge space, for example, a mixed gas of neon and xenon is enclosed as a discharge gas. In the present embodiment, a discharge gas having a xenon partial pressure of about 10% is used to improve luminance. The discharge space is partitioned into a plurality of sections by partition walls 34, and discharge cells are formed at the intersections between the display electrode pairs 28 and the data electrodes 32. These discharge cells discharge and emit light to display an image.

  Note that the structure of the panel 10 is not limited to the above-described structure, and for example, the panel 10 may include a stripe-shaped partition wall.

  FIG. 2 is an electrode array diagram of panel 10 in accordance with the exemplary embodiment of the present invention. In panel 10, n scanning electrodes SC1 to SCn (scanning electrode 22 in FIG. 1) and n sustaining electrodes SU1 to SUn (sustaining electrode 23 in FIG. 1) long in the row direction are arranged and long in the column direction. M data electrodes D1 to Dm (data electrode 32 in FIG. 1) are arranged. A discharge cell is formed at a portion where one pair of scan electrode SCi (i = 1 to n) and sustain electrode SUi (i = 1 to n) intersects with one data electrode Dj (j = 1 to m). , M × n discharge cells are formed in the discharge space. As shown in FIGS. 1 and 2, scan electrode SCi and sustain electrode SUi are formed in parallel with each other, and therefore, between scan electrodes SC1 to SCn and sustain electrodes SU1 to SUn. There is an interelectrode capacitance Cp.

  Next, a driving voltage waveform for driving panel 10 and its operation will be described. The plasma display device 1 performs gradation display by subfield method, that is, dividing one field period into a plurality of subfields and controlling light emission / non-light emission of each discharge cell for each subfield. Each subfield has an initialization period, an address period, and a sustain period. In the initializing period, initializing discharge is generated, and wall charges necessary for the subsequent address discharge are formed on each electrode. In the address period, address discharge is selectively generated in the discharge cells to emit light to form wall charges. In the sustain period, a number of sustain pulses corresponding to the luminance weight are alternately applied to the display electrode pairs, and a sustain discharge is generated in the discharge cells that have generated the address discharge to emit light.

  FIG. 3 is a diagram showing a subfield configuration in the embodiment of the present invention. FIG. 3 schematically shows a drive waveform between one field in the subfield method, and a drive voltage waveform of each subfield will be described later. In FIG. 3, one field is divided into 10 subfields (first SF, second SF,..., 10th SF), and each subfield is, for example, (1, 2, 3, 6, 11, 18, The subfield structure having luminance weights of 30, 44, 60, and 80) is shown. Further, the initialization operation is performed in all the discharge cells in the initialization period of the first SF, and the initialization operation is selectively performed in the discharge cells in which the sustain discharge is generated in the initialization period of the second SF to the tenth SF. In the sustain period of each subfield, the number of sustain pulses corresponding to the luminance weight of each subfield is applied to each display electrode pair. However, in the present invention, the number of subfields and the luminance weight of each subfield are not limited to the above values. Moreover, the structure which switches a subfield structure based on an image signal etc. may be sufficient.

  FIG. 4 is a drive voltage waveform diagram applied to each electrode of panel 10 in accordance with the exemplary embodiment of the present invention. FIG. 4 shows drive voltage waveforms in two subfields, but drive voltage waveforms in other subfields are substantially the same.

  In the first half of the initializing period of the first SF, 0 (V) is applied to the data electrodes D1 to Dm and the sustain electrodes SU1 to SUn, respectively, and the discharge start voltage with respect to the sustain electrodes SU1 to SUn is applied to the scan electrodes SC1 to SCn. A ramp waveform voltage that gently rises from the voltage Vi1 below toward the voltage Vi2 that exceeds the discharge start voltage is applied. While this ramp waveform voltage rises, a weak initializing discharge occurs between scan electrodes SC1 to SCn, sustain electrodes SU1 to SUn, and data electrodes D1 to Dm. Negative wall voltage is accumulated on scan electrodes SC1 to SCn, and positive wall voltage is accumulated on data electrodes D1 to Dm and sustain electrodes SU1 to SUn. Here, the wall voltage above the electrode represents a voltage generated by wall charges accumulated on the dielectric layer covering the electrode, the protective layer, the phosphor layer, and the like.

  In the latter half of the initialization period, positive voltage Ve1 is applied to sustain electrodes SU1 to SUn, and scan electrodes SC1 to SCn receive a discharge start voltage from voltage Vi3 that is equal to or lower than the discharge start voltage with respect to sustain electrodes SU1 to SUn. A ramp waveform voltage that gently falls toward the exceeding voltage Vi4 is applied. During this time, weak initializing discharges occur between scan electrodes SC1 to SCn, sustain electrodes SU1 to SUn, and data electrodes D1 to Dm, respectively. Then, the negative wall voltage above scan electrodes SC1 to SCn and the positive wall voltage above sustain electrodes SU1 to SUn are weakened, and the positive wall voltage above data electrodes D1 to Dm is adjusted to a value suitable for the write operation. The Thus, the initialization operation ends.

  As the drive voltage waveform in the initialization period, only the voltage waveform in the latter half of the initialization period may be applied as shown in the initialization period of the second SF in FIG. Initializing discharge is selectively generated in the discharge cells that have undergone sustain discharge in the sustain period of the field.

  In the subsequent address period, voltage Ve2 is applied to sustain electrodes SU1 to SUn, and voltage Vc is applied to scan electrodes SC1 to SCn.

  Next, the negative scan pulse voltage Va is applied to the scan electrode SC1 in the first row, and the data electrode Dk (k = 1 to m) of the discharge cell that should emit light in the first row among the data electrodes D1 to Dm. A positive address pulse voltage Vd is applied. At this time, the voltage difference at the intersection between the data electrode Dk and the scan electrode SC1 is the difference between the wall voltage on the data electrode Dk and the wall voltage on the scan electrode SC1 due to the difference between the externally applied voltages (Vd−Va). It becomes the sum and exceeds the discharge start voltage. Then, address discharge occurs between data electrode Dk and scan electrode SC1, and between sustain electrode SU1 and scan electrode SC1, positive wall voltage is accumulated on scan electrode SC1, and negative wall is applied on sustain electrode SU1. A voltage is accumulated, and a negative wall voltage is also accumulated on the data electrode Dk.

  In this manner, an address operation is performed in which an address discharge is caused in the discharge cells to be lit in the first row and wall voltage is accumulated on each electrode. On the other hand, the voltage at the intersection of the data electrodes D1 to Dm to which the address pulse voltage Vd is not applied and the scan electrode SC1 does not exceed the discharge start voltage, so that address discharge does not occur. The above address operation is performed until the discharge cell in the nth row of scan electrode SCn, and the address period ends.

  In the subsequent sustain period, first, positive sustain pulse voltage Vs is applied to scan electrodes SC1 to SCn, and 0 (V) is applied to sustain electrodes SU1 to SUn. Then, in the discharge cell in which the address discharge has occurred, the voltage difference between scan electrode SCi and sustain electrode SUi is the difference between the wall voltage on scan electrode SCi and the wall voltage on sustain electrode SUi. Exceeds the discharge start voltage. Then, a sustain discharge occurs between scan electrode SCi and sustain electrode SUi, and phosphor layer 35 emits light by the ultraviolet rays generated at this time. Then, a negative wall voltage is accumulated on scan electrode SCi, and a positive wall voltage is accumulated on sustain electrode SUi. Further, a positive wall voltage is accumulated on the data electrode Dk. In the discharge cells in which no address discharge has occurred during the address period, no sustain discharge occurs, and the wall voltage at the end of the initialization period is maintained.

  Subsequently, 0 (V) is applied to scan electrodes SC1 to SCn, and sustain pulse voltage Vs is applied to sustain electrodes SU1 to SUn. Then, in the discharge cell in which the sustain discharge has occurred, the voltage difference between the sustain electrode SUi and the scan electrode SCi exceeds the discharge start voltage, so that the sustain discharge occurs again between the sustain electrode SUi and the scan electrode SCi. A negative wall voltage is accumulated on SUi, and a positive wall voltage is accumulated on scan electrode SCi.

  Thereafter, similarly, the number of sustain pulses corresponding to the luminance weight is alternately applied to scan electrodes SC1 to SCn and sustain electrodes SU1 to SUn, and a potential difference is applied between the electrodes of the display electrode pair, so that the address discharge is performed in the address period. The sustain discharge is continuously performed in the discharge cell that has caused the failure.

  At the end of the sustain period, a so-called narrow pulse-like potential difference is applied between scan electrodes SC1 to SCn and sustain electrodes SU1 to SUn, and the positive wall voltage on data electrode Dk is left while scanning. The wall voltage on the electrode SCi and the sustain electrode SUi is erased. Thus, the maintenance operation in the maintenance period is completed.

  The subsequent operation of the subfield is substantially the same as the operation of the first SF, and thus description thereof is omitted.

  Next, a panel driving method in this embodiment will be described. In the present embodiment, the panel driving method is characterized in that a sustain pulse (hereinafter referred to as “reference pulse”) serving as a reference and a sustain pulse (hereinafter referred to as “specific pulse”) that rises more slowly than the reference pulse in the sustain period. Is used to generate a sustain discharge.

  FIG. 5 is a waveform diagram schematically showing the reference pulse and the specific pulse in the embodiment of the present invention. In the present embodiment, the rise time of the specific pulse (hereinafter also referred to as “sustain pulse B”) is about 550 nsec, and the rise time of the reference pulse (hereinafter also referred to as “sustain pulse A”) is about 400 nsec. Thus, sustain pulse B rises more slowly than sustain pulse A.

  The inventor generates a sustain discharge using the sustain pulse A that is the reference pulse and the sustain pulse B that is the specific pulse, and further generates the sustain pulse B continuously, thereby improving the display quality of the image on the panel 10. Experiments have found that the improvement, specifically, the afterimage phenomenon is reduced.

  The afterimage phenomenon is a phenomenon that occurs because the emission intensity of a discharge cell changes depending on the emission history of the discharge cell. For example, an afterimage is recognized when a still image is displayed for a long time, and after the discharge cells that emit light and the discharge cells that do not emit light continue to maintain the state for a certain period of time, the entire screen emits light brightly. At this time, if the emission intensity of the discharge cell that emits light is higher than the emission intensity of the discharge cell that did not emit light, a positive afterimage is generated, and vice versa. Will occur. In addition, as the time for displaying a still image becomes longer, such an afterimage tends to become stronger.

  A sustain pulse generation pattern capable of improving the afterimage phenomenon will be described with reference to the drawings. FIG. 6 is a schematic diagram showing generation patterns of the reference pulse and the specific pulse in the embodiment of the present invention. In this drawing, the sustain pulse A, which is a reference pulse, is represented as “A”, and the sustain pulse B, which is a specific pulse, is represented as “B”.

  In the present embodiment, as shown in FIG. 6, after sustain pulse B is applied to scan electrode 22 during sustain period, sustain pulse B is continuously applied to sustain electrode 23. Subsequently, after sustain pulse A is applied to scan electrode 22, sustain pulse A is subsequently applied to sustain electrode 23. After sustain pulse A is applied to scan electrode 22 and sustain electrode 23 continuously six times, sustain pulse B is again applied to scan electrode 22 and sustain electrode 23 again. This series of operations is repeated until a sustain pulse is applied to the display electrode pair 28 a predetermined number of times (the number of times the luminance weight is multiplied by the luminance magnification) in the subfield.

  As described above, in the present embodiment, after the sustain pulse B that is the specific pulse is generated twice in succession, the sustain pulse A that is the reference pulse is generated six times in succession. It is configured.

  The inventor has experimentally confirmed that the afterimage phenomenon can be reduced by using the panel driving method in the present embodiment. Although the mechanism of occurrence of the above-described afterimage phenomenon has not yet been elucidated, this afterimage phenomenon is considered to be one of the causes due to variations in the emission intensity in the discharge cells. The light emission intensity is affected by the state of wall charges in the discharge cell. In order to make the wall charges as uniform as possible, it is considered effective to generate a sustain discharge while changing the intensity of the sustain discharge. However, the wall charge state does not easily change when the intensity of the sustain discharge is changed only once. Therefore, the generation of the sustain pulse A and the sustain pulse B as described above affects the reduction of the afterimage phenomenon. It is thought to give.

  The number of consecutive occurrences of sustain pulse A and sustain pulse B is preferably set optimally according to the sign of the afterimage to be generated and its strength, but sustain pulse A and sustain pulse B are each continuous. Thus, it has been clarified that the afterimage phenomenon itself can be reduced and the display brightness of each discharge cell can be made uniform.

  Next, a driving circuit for driving the panel 10 and its operation will be described. FIG. 7 is a circuit block diagram of plasma display device 1 using panel 10 in accordance with the exemplary embodiment of the present invention. The plasma display apparatus 1 includes a panel 10, an image signal processing circuit 51, a data electrode drive circuit 52, a scan electrode drive circuit 53, a sustain electrode drive circuit 54, a timing generation circuit 55, and a power supply circuit that supplies necessary power to each circuit block. (Not shown).

  The image signal processing circuit 51 converts the input image signal sig into image data indicating light emission / non-light emission for each subfield. The data electrode drive circuit 52 converts the image data for each subfield into signals corresponding to the data electrodes D1 to Dm, and drives the data electrodes D1 to Dm.

  The timing generation circuit 55 generates various timing signals for controlling the operation of each circuit block based on the horizontal synchronization signal H and the vertical synchronization signal V, and supplies them to each circuit block. Scan electrode driving circuit 53 has sustain pulse generating circuit 100 for generating sustain pulses to be applied to scan electrodes SC1 to SCn in the sustain period, and drives each of scan electrodes SC1 to SCn based on a timing signal. Sustain electrode drive circuit 54 has sustain pulse generation circuit 200 for generating sustain pulses to be applied to sustain electrodes SU1 to SUn during the sustain period, and drives sustain electrodes SU1 to SUn based on a timing signal.

  Next, details and operation of sustain pulse generating circuits 100 and 200 will be described. FIG. 8 is a circuit diagram of sustain pulse generation circuits 100 and 200 according to the embodiment of the present invention. In FIG. 8, the interelectrode capacitance of the panel 10 is shown as Cp, and the circuit for generating the scan pulse and the initialization voltage waveform is omitted.

  Sustain pulse generation circuit 100 includes a power recovery unit 110 and a clamp unit 120. The power recovery unit 110 includes a power recovery capacitor C10, switching elements Q11 and Q12, backflow prevention diodes D11 and D12, and a resonance inductor L10. In addition, the clamp unit 120 includes a switching element Q13 for clamping the scan electrode 22 to the power source VS having a voltage value Vs, and a switching element Q14 for clamping the scan electrode 22 to the ground potential. The power recovery unit 110 and the clamp unit 120 are connected to the scan electrode 22 which is one end of the interelectrode capacitance Cp of the panel 10 via a scan pulse generation circuit (not shown because it is in a short circuit state during the sustain period). Yes.

  The power recovery unit 110 causes the interelectrode capacitance Cp and the inductor L10 to resonate with each other so as to rise and fall the sustain pulse. When the sustain pulse rises, the charge stored in the power recovery capacitor C10 is transferred to the interelectrode capacitance Cp via the switching element Q11, the diode D11, and the inductor L10. When the sustain pulse falls, the charge stored in the interelectrode capacitance Cp is returned to the power recovery capacitor C10 via the inductor L10, the diode D12, and the switching element Q12. In this way, the sustain pulse is applied to the scan electrode 22. Thus, since the power recovery unit 110 drives the scan electrode 22 by LC resonance, power consumption is reduced. The power recovery capacitor C10 has a sufficiently large capacity compared to the interelectrode capacitance Cp, and is charged to about Vs / 2, which is half of the voltage value Vs of the power supply VS so as to serve as a power supply for the power recovery unit 110. ing.

  The clamp unit 120 connects the scan electrode 22 to the power source VS via the switching element Q13, and clamps the scan electrode 22 to the voltage Vs. Further, the scanning electrode 22 is grounded via the switching element Q14 and clamped to 0 (V). In this way, the clamp unit 120 drives the scanning electrode 22. Therefore, the impedance at the time of voltage application by the clamp part 120 is small, and a large discharge current due to a strong sustain discharge can be flowed stably.

  Thus, sustain pulse generating circuit 100 applies sustain pulses to scan electrode 22 using power recovery unit 110 and clamp unit 120 by controlling switching elements Q11, Q12, Q13, and Q14. Note that these switching elements can be configured using generally known elements such as MOSFETs and IGBTs.

  Sustain pulse generation circuit 200 clamps power recovery unit 210 having power recovery capacitor C20, switching elements Q21 and Q22, backflow prevention diodes D21 and D22, and resonance inductor L20, and sustain electrode 23 at voltage Vs. A switching element Q23 for clamping and a clamping part 220 having a switching element Q24 for clamping the sustain electrode 23 to the ground potential, and is connected to the sustain electrode 23 which is one end of the interelectrode capacitance Cp of the panel 10. The operation of sustain pulse generating circuit 200 is the same as that of sustain pulse generating circuit 100, and thus description thereof is omitted.

  Note that the period of LC resonance between the inductor L10 of the power recovery unit 110 and the interelectrode capacitance Cp of the panel 10 and the period of LC resonance between the inductor L20 of the power recovery unit 210 and the interelectrode capacitance Cp (hereinafter referred to as “resonance period”). Can be obtained by the calculation formula “2π√ (LCp)”, where L is the inductance of the inductors L10 and L20. In this embodiment, inductors L10 and L20 are set so that the resonance period in power recovery units 110 and 210 is about 1000 nsec.

  Next, the operation of the sustain pulse generation circuit will be described with reference to FIG. FIG. 9 is a waveform diagram of a reference pulse in the embodiment of the present invention. Here, sustain pulse generating circuit 100 on the side of scan electrode 22 will be described, but sustain pulse generating circuit 200 on the side of sustain electrode 23 has the same circuit configuration, and its operation is also substantially the same. First, sustain pulse A that is the reference pulse shown in FIG. 9 will be described.

(Period T11)
At time t1, switching element Q11 is turned on. Then, electric charge starts to move from the power recovery capacitor C10 to the scan electrode 22 through the switching element Q11, the diode D11, and the inductor L10, and the voltage of the scan electrode 22 starts to rise.

(Period T21)
In the sustain pulse A, the switching element Q13 is turned ON at time t21 before the time ½ of the resonance period elapses from time t1. Then, since the scan electrode 22 is connected to the power source VS through the switching element Q13, the scan electrode 22 is clamped to the voltage Vs. When scan electrode 22 is clamped to voltage Vs, the voltage difference between scan electrode 22 and sustain electrode 23 exceeds the discharge start voltage in the discharge cell in which the address discharge has occurred, and a sustain discharge occurs.

  As described above, in the present embodiment, the resonance period between the inductor L10 and the interelectrode capacitance Cp is set to about 1000 nsec, and the rise of the sustain pulse applied to the scan electrode 22, that is, from time t1 to time t21. The period T11 is set to about 400 nsec, which is shorter than 1/2 of the resonance period.

(Period T3)
At time t31, switching element Q12 is turned on. Then, charge starts to move from the scan electrode 22 to the capacitor C10 through the inductor L10, the diode D12, and the switching element Q12, and the voltage of the scan electrode 22 starts to drop. Since the inductor L10 and the interelectrode capacitance Cp form a resonance circuit, the voltage of the scan electrode 22 decreases to near 0 (V) at a time after about half of the resonance period has elapsed from the time t3. To do.

(Period T4)
At time t4, switching element Q14 is turned on. Then, since the scan electrode 22 is directly grounded through the switching element Q14, the scan electrode 22 is clamped to 0 (V).

  Thus, the rise time of sustain pulse A is about 400 nsec, which is set to be shorter than ½ of about 1000 nsec of the resonance period between inductor L10 and interelectrode capacitance Cp.

  FIG. 10 is a waveform diagram of a specific pulse in the embodiment of the present invention. Next, sustain pulse B, which is a specific pulse with a slower rise than the reference pulse shown in FIG. 10, will be described.

(Period T12)
At time t1, switching element Q11 is turned on. Then, electric charge starts to move from the power recovery capacitor C10 to the scan electrode 22 through the switching element Q11, the diode D11, and the inductor L10, and the voltage of the scan electrode 22 starts to rise. Since the inductor L10 and the interelectrode capacitance Cp form a resonance circuit, the voltage of the scan electrode 22 rises to near Vs at a time after a half of the resonance period has elapsed from the time t1.

(Period T22)
In the sustain pulse B, the switching element Q13 is turned ON at time t22 after a time ½ of the resonance period has elapsed from time t1. Then, since scan electrode 22 is directly connected to power supply VS through switching element Q13, scan electrode 22 is clamped at voltage Vs, and a sustain discharge is generated.

  In sustain pulse B, the rise of the sustain pulse applied to scan electrode 22, that is, the time period T12 from time t1 to time t22 is set to about 550 nsec. In sustain pulse B, period T22 is set shorter than period T21 by an amount corresponding to the rise time longer than sustain pulse A, and the length of one cycle from the rise to the fall of sustain pulse A and sustain pulse B is set. Is not changing.

  The operations in (period T3) and (period T4) are the same as those in sustain pulse A.

  Thus, the rise time of the sustain pulse A, which is the reference pulse, is about 400 nsec, which is set to be shorter than 1/2 of about 1000 nsec of the resonance period between the inductor L10 and the interelectrode capacitance Cp, and is a specific pulse. The rise time of sustain pulse B is about 550 nsec, and is set longer than ½ of the same resonance period.

  The above is the operation of the sustain pulse generation circuit for generating the sustain pulse A and the sustain pulse B in the present embodiment. As described above, the switching for controlling the voltage application to the display electrode pair by the power recovery unit By controlling the time during which the elements (switching elements Q11 and Q21) are kept ON, two types of sustain pulses having different rising edges are generated. Then, the sustain pulse A, which is a reference pulse, and the sustain pulse B, which is a specific pulse whose rise is more gradual than the reference pulse, are successively generated, thereby improving the image display quality on the panel 10.

  In this embodiment, the configuration in which the specific pulse is generated twice continuously and the reference pulse is generated six times in succession has been described. However, the present invention is not limited to this configuration. FIG. 11 is a schematic diagram showing another example of the generation pattern of the reference pulse and the sustain pulse in the embodiment of the present invention. For example, as shown in FIG. 11, the specific pulse may be generated four times in succession and the reference pulse may be generated four times in succession. Or although not illustrated, the structure which generate | occur | produces a specific pulse 3 times continuously and the structure which generates 5 times continuously may be sufficient. In this embodiment, the display quality of the image is improved by generating specific pulses continuously, and how many times the reference pulse and specific pulse are generated each time depends on the characteristics of the panel and the panel. It is desirable to set the optimal value according to the specifications.

  In the present embodiment, the configuration in which the reference pulse is set to be shorter than 1/2 of the resonance period and the specific pulse is set to be longer than 1/2 of the resonance period has been described. However, the configuration is not limited to this configuration. For example, the specific pulse may be set shorter than ½ of the resonance period, and the reference pulse may be set shorter than that.

  Further, in the present embodiment, no particular mention has been made of driving according to the brightness of the image, but the number of consecutive occurrences of the reference pulse and the specific pulse, for example, based on the APL of the image signal or the lighting rate for each subfield. It does not matter as a configuration for controlling. For example, an image in which an afterimage phenomenon is likely to occur is a case where a high-luminance region exists in a low-luminance background, and thus the lighting rate of the entire screen is low. Also, the afterimage phenomenon is recognized as an afterimage for an image having a high luminance on the entire screen. Therefore, when the lighting rate is low, a sustain pulse generation pattern giving priority to suppression of the afterimage phenomenon may be used, and when the lighting rate is high, a sustain pulse generation pattern giving priority to suppression of the variation in emission intensity for each discharge cell may be used.

  Further, in the present embodiment, one field is divided into 10 subfields (first SF, second SF,..., 10th SF), and each subfield is (1, 2, 3, 6, 11, 18, 30, 44, 60, 80), but the present invention is not limited to the above values for the number of subfields and the luminance weight of each subfield.

  Further, in the present embodiment, the configuration in which the same inductor is used for power supply and for power recovery has been described. However, the configuration is not limited to this configuration, and different inductors are used for power supply and power recovery. For example, the power supply path and the power recovery path may be separated from each other.

  In this embodiment, the xenon partial pressure of the discharge gas is set to 10%. However, other xenon partial pressures may be used. In this case, the driving voltage may be set according to the panel.

  Further, the specific numerical values used in the present embodiment are merely examples, and it is desirable to appropriately set the values appropriately according to the characteristics of the panel, the specifications of the plasma display device, and the like.

  The panel driving method and the plasma display apparatus of the present invention can reduce the afterimage phenomenon itself while performing faithful image display, and can equalize the display luminance of each discharge cell. Useful as a device.

The disassembled perspective view which shows the structure of the panel in embodiment of this invention Electrode arrangement of the panel The figure which shows the subfield structure in embodiment of this invention Drive voltage waveform diagram applied to each electrode of the panel in the embodiment of the present invention Waveform diagram showing an outline of a reference pulse and a specific pulse in the embodiment of the present invention Schematic showing the generation pattern of the reference pulse and specific pulse The circuit block diagram of the plasma display apparatus using the panel in embodiment of this invention Circuit diagram of sustain pulse generation circuit in the embodiment of the present invention Waveform diagram of reference pulse in the embodiment of the present invention Waveform diagram of specific pulse in the embodiment of the present invention Schematic showing another example of the generation pattern of the reference pulse and the sustain pulse in the embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma display apparatus 10 Panel 21 (made of glass) Front plate 22 Scan electrode 23 Sustain electrode 24, 33 Dielectric layer 25 Protective layer 28 Display electrode pair 31 Back plate 32 Data electrode 34 Partition 35 Phosphor layer 51 Image signal processing circuit 52 Data electrode drive circuit 53 Scan electrode drive circuit 54 Sustain electrode drive circuit 55 Timing generation circuit 100, 200 Sustain pulse generation circuit 110, 210 Power recovery unit 120, 220 Clamp unit C10, C20 (for power recovery) Capacitor Cp Interelectrode capacitance Q11, Q12, Q13, Q14, Q21, Q22, Q23, Q24, Q28, Q29 Switching element D11, D12, D21, D22 (For backflow prevention) Diode L10, L20 Inductor

Claims (3)

A method of driving a plasma display panel comprising a plurality of discharge cells having a display electrode pair consisting of a scan electrode and a sustain electrode,
One field includes an initializing period for generating an initializing discharge in the discharge cell, an addressing period for generating an addressing discharge in the discharge cell, and applying a sustain pulse to the display electrode pair to generate the addressing discharge. A plurality of subfields having a sustain period for generating a sustain discharge in a discharge cell;
In the sustain period, the sustain discharge is generated using a reference sustain pulse and a specific pulse whose rise is more gradual than the reference sustain pulse, and at least two consecutive specific pulses and two or more continuous pulses. Alternately generating the reference sustain pulse, and based on the lighting rate for each subfield, configured to control the number of consecutive occurrences of the specific pulse and the reference pulse,
A method for driving a plasma display panel, wherein when the lighting rate is lower than a predetermined value, the number of consecutive occurrences of the specific pulse and the reference pulse is increased as compared with a case where the lighting rate is high. A plasma display panel having a plurality of discharge cells each having a display electrode pair consisting of a scan electrode and a sustain electrode;
One field is divided into a plurality of subfields having an initialization period, an address period, and a sustain period, and sustain pulses are alternately applied to the display electrode pairs in the sustain period to generate a sustain discharge in the discharge cells. A sustain pulse generation circuit,
The sustain pulse generating circuit includes: a power recovery unit that applies a voltage to the display electrode pair by resonating a capacitance between the electrodes of the display electrode pair and a power recovery inductor; A clamp portion for clamping to ground potential,
Using a reference pulse whose rise time of sustain pulse is less than ½ of a resonance period between the capacitance between the electrodes and the power recovery inductor, and a specific pulse having a rise time longer than the reference pulse It is configured to generate a sustain discharge, and is configured to alternately generate the specific pulse that is continuous twice or more and the reference pulse that is continuous twice or more, and based on the lighting rate for each subfield, Configured to control the number of consecutive occurrences of the pulse and the reference pulse,
When the lighting rate is lower than a predetermined value, the number of consecutive occurrences of the specific pulse and the reference pulse is increased more than when the lighting rate is high. 3. The plasma display apparatus according to claim 2, wherein the sustain pulse generation circuit is configured to alternately generate the specific pulse that is continued four times or more and the reference pulse that is continued four times or more.

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