JP2007057633A - Plasma display panel driving circuit and plasma display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a PDP driving circuit and a plasma display device that control a discharge current upon sustain discharge by controlling an impedance in a discharge path, and thereby, that display an image with suppressed luminance without degrading the grayscale property. <P>SOLUTION: The PDP driving circuit is equipped with: a scan electrode driving circuit 501 having a sustain pulse generating circuit 511, an initialization waveform generating circuit 52, a scan pulse generating circuit 53, and a switching circuit comprising switching elements S9<SB>1</SB>, S9<SB>2</SB>, S10<SB>1</SB>, S10<SB>2</SB>; and a sustain pulse generating circuit 61. The switching circuit is configured by connecting in series a first switch comprising the switching elements S9<SB>1</SB>, S9<SB>2</SB>connected in parallel and a second switch comprising switching elements S10<SB>1</SB>, S10<SB>2</SB>connected in parallel with body diodes disposed in a direction opposite to those of the switching elements S9<SB>1</SB>, S9<SB>2</SB>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  An AC surface discharge type plasma display panel (hereinafter abbreviated as “PDP”) representative of an AC type includes a front plate made of a glass substrate formed by arranging scan electrodes and sustain electrodes for performing surface discharge, and data electrodes. And a back plate made of a glass substrate formed by arranging the electrodes in parallel so as to form a discharge space in the gap so that both electrodes form a matrix, and the outer periphery thereof is a sealing material such as glass frit It is comprised by sealing by. Discharge cells partitioned by barrier ribs are provided between both the front and back substrates, and a phosphor layer is formed in the cell space between the barrier ribs. In the PDP having such a configuration, ultraviolet light is generated by gas discharge, and phosphors of each color of red (R), green (G), and blue (B) are excited by the ultraviolet light to emit light, thereby performing color display. Is going.

  FIG. 9 is a perspective view showing the structure of the PDP 10. On the glass front plate 20 which is the first substrate, a plurality of display electrodes which are paired with a stripe-shaped scan electrode 22 and a stripe-shaped sustain electrode 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 stripe-shaped data electrodes 32 covered with a dielectric layer 33 are formed on the back plate 30 as the second substrate so as to three-dimensionally intersect the scan electrodes 22 and the sustain electrodes 23. A plurality of barrier ribs 34 are disposed on the dielectric layer 33 in parallel with the data electrodes 32, and a phosphor layer 35 is provided on the dielectric layer 33 between the barrier ribs 34. Further, the data electrode 32 is disposed at a position between the adjacent partition walls 34.

  The front plate 20 and the back plate 30 are arranged to face each other with a minute discharge space so that the scan electrode 22, the sustain electrode 23, and the data electrode 32 are orthogonal to each other, and the outer peripheral portion thereof is made of glass frit or the like. It is sealed with a sealing material. In the discharge space, for example, a mixed gas of neon (Ne) and xenon (Xe) is sealed as a discharge gas. The discharge space is partitioned into a plurality of sections by partition walls 34, and phosphor layers 35 that emit red (R), green (G), and blue (B) light are sequentially disposed in each section. A discharge cell is formed at a portion where the scan electrode 22 and the sustain electrode 23 intersect with the data electrode 32, and one adjacent pixel is formed by three adjacent discharge cells on which the phosphor layers 35 that emit light of each color are formed. The An area where the discharge cells constituting this pixel are formed becomes an image display area, and the periphery of the image display area becomes a non-display area where image display is not performed, such as an area where glass frit is formed.

FIG. 10 is an electrode array diagram of the PDP 10. N rows of scan electrodes SC _{1 to} SC _n (scan electrodes 22 in FIG. 9) and n rows of sustain electrodes SU _{1 to} SU _n (sustain electrodes 23 in FIG. 9) are alternately arranged in the row direction. Are arranged in m rows of data electrodes D _{1 to} D _m (data electrodes 32 in FIG. 9). A discharge cell C _{i, j} including a pair of scan electrodes SC _i , sustain electrodes SU _i (i = 1 to n) and one data electrode D _j (j = 1 to m) is formed in the discharge space. The total number of discharge cells C is (m × n).

  In the PDP 10 having such a configuration, color display is performed by generating ultraviolet rays by gas discharge and exciting the phosphors of R, G, and B colors with the ultraviolet rays to emit light. Further, the PDP 10 divides one field period into a plurality of subfields, and performs gradation display by being driven by a combination of subfields that emit light. Each subfield includes an initialization period, an address period, and a sustain period. In order to display image data, different signal waveforms are applied to the respective electrodes in the initialization period, the address period, and the sustain period.

  FIG. 11 is a diagram showing each drive voltage waveform applied to each electrode of the PDP 10. As shown in FIG. 11, each subfield has an initialization period, an address period, and a sustain period. Each subfield performs substantially the same operation except that the number of sustain pulses in the sustain period is changed in order to change the weight of the light emission period, and the operation principle in each subfield is also substantially the same. The operation will be described for only one subfield.

First, in the initialization period, for example, a positive pulse voltage is applied to all the scan electrodes SC _{1 to} SC _n, and the dielectric layer 24 covering the scan electrodes SC _{1 to} SC _n and the sustain electrodes SU _{1 to} SU _n is applied. Necessary wall charges are accumulated on the protective layer 25 and the phosphor layer 35. In addition, it has a function of generating priming (priming for discharge = excited particles) for reducing the discharge delay and generating the address discharge stably.

Specifically, in the half of the initializing period, holds the data electrodes _D 1 to D _m, sustain electrodes _SU 1 to SU _n in each 0 (V), the scan electrodes _SC 1 to SC _n, data electrodes D A ramp waveform voltage that gradually rises from a voltage V _{i1 that is} equal to or lower than the discharge start voltage to a voltage V _i2 that exceeds the discharge start voltage is applied to _{1 to} D _m . While this ramp waveform voltage rises, the _first weak initializing discharge occurs between scan electrodes SC _{1 to} SC _n and sustain electrodes SU _{1 to} SU _n and data electrodes D _{1 to} D _m , respectively. Negative wall voltage is accumulated on scan electrodes _SC 1 to SC _n top, to the data electrodes _D 1 to D _m and sustain electrodes _SU 1 to SU _n positive wall voltage is accumulated. Here, the wall voltage on the electrode represents a voltage generated by wall charges accumulated on the dielectric layer covering the electrode.

In the second half of the initializing period, maintaining the sustain electrodes _SU 1 to SU _n to a positive voltage Ve, the scan electrodes _SC 1 to SC _n, the voltage _{V i3} which is a discharge start voltage or less with respect to sustain electrodes _SU 1 to SU _{n Is} applied with a ramp waveform voltage that gradually falls toward voltage V _i4 exceeding the discharge start voltage. During this time, the second weak initializing discharge occurs between the scan electrodes SC _{1 to} SC _n and the sustain electrodes SU _{1 to} SU _n and the data electrodes D _{1 to} D _m , respectively. Then, negative wall voltage and sustain electrodes _SU 1 to SU _n positive wall voltage on scan electrodes _SC 1 to SC _n upper are weakened, positive wall voltage on data electrodes _D 1 to D _m upper address operation It is adjusted to a suitable value. This completes the initialization operation (hereinafter, the drive voltage waveform applied to each electrode during the initialization period is abbreviated as “initialization waveform”).

Next, in the address period, scanning is performed by sequentially applying a negative scan pulse to all the scan electrodes SC _{1 to} SC _n . Then, while scanning the scan electrodes _SC 1 to SC _n, and applies the positive write pulse voltage to the data electrodes _D 1 to D _m based on the display data. Thus, address discharge is generated between scan electrodes SC _{1 to} SC _n and data electrodes D _{1 to} D _m, and wall charges are formed on the surface of protective layer 25 on scan electrodes SC _{1 to} SC _n .

Specifically, in the address period, scan electrodes SC _{1 to} SC _n are temporarily held at voltage Vscn. Next, in the address operation of the discharge cells C _{p, 1 to} C _{p, m} (p is an integer of ₁ to n), the scan pulse voltage Vad is applied to the scan electrode SC _p and the data electrodes D _{1 to} D _m are applied. among p data electrode D _q corresponding to the video signal to be displayed on line _{(D q} data electrodes selected based on the video signal of the D ₁ to D _m) for applying a positive write pulse voltage Vd to. Thus, the discharge cells corresponding to the intersections of the scan electrodes SC _P to which the scan pulse voltage and the write pulse voltage data electrode is applied D _q is applied C _p, writing discharge _q occur. The address discharge by the discharge cell C _p, a positive voltage to the scan electrodes SC _p top of _q is accumulated, and a negative voltage is accumulated on sustain electrode SU _p top, the write operation is completed. Thereafter, the same address operation is performed until the discharge cell C _{n, q} in the _n- th row _, and the address operation is completed.

In the subsequent sustain period, applying a sufficient voltage to maintain the discharge between the fixed period, the scan electrodes _SC 1 to SC _n and sustain electrodes _SU 1 to SU _n. Thus, the scan electrodes _SC 1 discharge plasma between to SC _n and sustain electrodes _SU 1 to SU _n are generated, a period of time, to excite the phosphor to emit light layer 35. At this time, in the discharge space where the address pulse voltage is not applied in the address period, no discharge occurs and excitation light emission of the phosphor layer 35 does not occur.

Specifically, in the sustain period, scan electrodes SC _{1 to} SC _n are once returned to 0 (V), and then positive sustain pulse voltage Vsus is applied to scan electrodes SC _{1 to} SC _n . Thereafter, returning the sustain electrodes _SU 1 to SU _n to 0 (V). At this time, the voltage between the discharge cell C _p having generated the address _discharge, the scan electrode SC _p upper part of _q and sustain electrode SU _p top, in addition to the positive sustain pulse voltage Vsus, scanning in the address periods electrode SC _p It is subject to and sustain electrode SU _p accumulated wall voltage in the upper, larger than the discharge start voltage, first sustain discharge is generated. A discharge cell C _p having undergone the sustain _discharge, the _q, negative voltage to the scan electrodes SC _p top so as to cancel the potential difference between the sustain electrode SU _p and scan electrode SC _P during the sustain discharge occurs is accumulated, sustain electrodes A positive voltage is accumulated on the top of SU _p . Thus, the first sustain discharge is completed. After the first sustain discharge, is applied to Vsus to the sustain electrodes _SU 1 to SU _n, then returned to the scan electrodes _SC 1 to SC _n to 0 (V). In this case, first discharge cell C _p having undergone the sustain _discharge, the voltage between the scan electrodes SC _p upper and the sustain electrode SU _p upper part of _q, in addition to the positive sustain pulse voltage Vsus, maintaining first In discharge, the wall voltages accumulated on scan electrode SC _p and sustain electrode SU _p are added to become higher than the discharge start voltage, and a second sustain discharge is generated. Thereafter, in the same manner, by applying sustain pulses alternately to scan electrodes SC _{1 to} SC _n and sustain electrodes SU _{1 to} SU _n , the number of sustain pulses is _equal to the number of sustain pulses for discharge cells C _{p and q in} which address discharge has occurred. The sustain discharge is continuously performed.

  FIG. 12 is a block diagram showing an electrical configuration of a plasma display device incorporating the PDP 10. The plasma display device shown in FIG. 12 includes an AD converter 1, a video signal processing circuit 2, a subfield processing circuit 3, a data electrode driving circuit 4, a scanning electrode driving circuit 5, a sustain electrode driving circuit 6, and a PDP 10.

  The AD converter 1 converts the input analog video signal into a digital video signal. The video signal processing circuit 2 emits and displays the input digital video signal on the PDP 10 by a combination of a plurality of subfields having different light emission period weights, and controls each subfield from the video signal of one field. Convert to data.

  The subfield processing circuit 3 generates a data electrode drive circuit control signal, a scan electrode drive circuit control signal, and a sustain electrode drive circuit control signal from the subfield data created by the video signal processing circuit 2, and drives the data electrode Output to the circuit 4, the scan electrode drive circuit 5, and the sustain electrode drive circuit 6, respectively.

As described above, in the PDP 10, n rows of scan electrodes SC _{1 to} SC _n (scan electrodes 22 in FIG. 9) and n rows of sustain electrodes SU _{1 to} SU _n (sustain electrodes 23 in FIG. 9) are alternately arranged in the row direction. The data electrodes D _{1 to} D _m (data electrodes 32 in FIG. 9) are arranged in the column direction. A discharge cell C _{i, j} including a pair of scan electrodes SC _i , sustain electrodes SU _i (i = 1 to n) and one data electrode D _j (j = 1 to m) is formed in the discharge space (m Xn) One pixel is composed of three discharge cells that are formed and emit light in red, green, and blue colors.

Data electrode driving circuit 4 are independently drives each data electrode D _j on the basis of the control signal for the data electrode driving circuit.

Scan electrode drive circuit 5 includes sustain pulse generation circuit 51 for generating sustain pulses to be applied to scan electrodes SC _{1 to} SC _n in the sustain period, and each scan electrode SC _{1 to} SC _n is independently provided. Can be driven. Then, each of the scan electrodes SC _{1 to} SC _n is independently driven based on the scan electrode drive circuit control signal.

Sustain electrode driving circuit 6 includes a sustain pulse generating circuit 61 for generating sustain pulses applied to the sustain electrodes _SU 1 to SU _n in the sustain period within, summarizes all the sustain electrodes _SU 1 to SU _n of PDP10 Can be driven. Then, driving the sustain electrodes _SU 1 to SU _n based on the control signal the sustain electrode driving circuit.

  In such a plasma display device, various power consumption reduction techniques have been proposed in order to reduce the power consumption.

  Focusing on the fact that the PDP 10 is a capacitive load as one of the technologies for reducing power consumption, LC resonance is performed between the inductor and the capacitive load of the PDP 10 by a resonance circuit including the inductor as a component, and the capacitance of the PDP 10 A so-called power recovery circuit is disclosed in which power stored in a sexual load is recovered in a capacitor for power recovery, and the recovered power is reused for driving the PDP 10 (see, for example, Patent Document 1).

In this technique, for example, the power recovered from the PDP 10 is reused to apply the sustain pulse voltage to the scan electrodes SC _{1 to} SC _n and the sustain electrodes SU ₁ to SU _n in the sustain period, and the power consumed in the sustain period is reduced. By reducing, power consumption can be reduced.

That is, the sustain pulse generation circuit 51 includes a resonance circuit including an inductor, that is, a power recovery circuit, and recovers the electric power stored in the capacitive load of the PDP 10 (capacitive load generated in the scan electrodes SC _{1 to} SC _n ). Then, the collected power is reused as drive power for scan electrodes SC _{1 to} SC _n to reduce power consumption. Also includes a power recovery circuit in sustain pulse generating circuit 61, the electric power stored in the (capacitive load generated in the sustain electrodes SU ₁ ~SU _n) PDP10 of the capacitive load is recovered, maintaining the recovered power in the structure is reused as driving power of the electrodes _SU 1 to SU _n, to reduce power consumption. This configuration will be described with reference to the drawings.

  FIG. 13 is a circuit diagram of sustain pulse generation circuit 61 provided in scan electrode drive circuit 5 and sustain electrode drive circuit 6 provided with a power recovery circuit.

  Scan electrode drive circuit 5 includes sustain pulse generation circuit 51, initialization waveform generation circuit 52, and scan pulse generation circuit 53.

The sustain pulse generation circuit 51 includes a constant voltage power source V1 having a voltage value Vsus, a power recovery unit including a coil L1, a recovery capacitor C1, switching elements S1 and S2, and backflow prevention diodes D1 and D2, and switching elements S5 and S6. And a voltage clamp part having The power recovery unit, the coil L1 PDP 10 of the capacitive load by using a (capacitive load generated in scan electrodes SC ₁ to SC _n) and the coil L1 is an inductance element by LC resonance, the power of recovery and supply I do. At the time of power recovery, the power stored in the capacitive load generated in the scan electrodes SC _{1 to} SC _n is moved to the recovery capacitor C 1 via the current backflow prevention diode D 2 and the switching element S 2. When supplying electric power, the electric power stored in the recovery capacitor C1 is moved to the PDP 10 (scan electrodes SC _{1 to} SC _n ) via the switching element S1 and the backflow prevention diode D1. Thus, scan electrodes SC _{1 to} SC _n are driven in the sustain period. Therefore, since the power recovery unit drives the scan electrodes SC _{1 to} SC _n by LC resonance without supplying power from the constant voltage power source V 1 during the sustain period, the power consumption is theoretically 0.

On the other hand, the voltage clamp unit clamps the scan electrodes _SC 1 to SC _n and supplies power to the scan electrodes _SC 1 to SC _n from the constant-voltage power supply V1 voltage value Vsus through the switching element S5 is the voltage value Vsus, Further, by clamping to the ground potential scan electrodes _SC 1 to SC _n via the switching element S6, to drive the scan electrodes _SC 1 to SC _n. Therefore, when the scan electrodes SC _{1 to} SC _n are driven by the voltage clamp unit, the power supply impedance is very small, and the rising and falling edges of the sustain pulse become steep, but the power consumption due to the supply of power from the power source. Occurs.

Thus, the sustain pulse generating circuit 51, by switching the switching elements S1, S2, S5, S6, switching power recovery unit and the voltage clamp unit, for generating a sustain pulse to be applied to scan electrodes _SC 1 to SC _n. At this time, in the sustain pulse generation circuit 51 using LC resonance, power is supplied by the power recovery unit until the voltage of the sustain pulse reaches a maximum value, and then switched to the voltage clamp unit, so that the theoretical power consumption is 0. It is possible to drive using the power recovery unit as much as possible, and to reduce the power consumption of the scan electrode drive circuit 5.

  The switching elements S1, S2, S5, and S6 are generally known elements that perform a switching operation such as a MOSFET. A MOSFET is generally a parasitic diode called a body diode (a diode generated parasitically in the structure of the MOSFET) in parallel to the portion that performs the switching operation, and the anode and cathode that are opposite to the portion that performs the switching operation. (Hereinafter, such a configuration is referred to as “reverse parallel”). For this reason, the switching element can flow a current in the forward direction with respect to the body diode even when the switching operation is in a cut-off state.

The initialization waveform generating circuit 52 includes switching elements S21 and S22 made of a generally known element that performs a switching operation such as a MOSFET, a constant voltage power source V2 having a voltage value Vset, and a constant voltage power source V3 having a negative voltage value Vad. is doing. Then, supplies power to the scan electrodes _SC 1 to SC _n from the constant-voltage power supply V2 through the switching element S21, also, a negative potential to the scan electrodes _SC 1 to SC _n from the constant-voltage power supply V3 via the switching element S22 To generate an initialization waveform. The switching element S21 is connected to the main discharge path (maintenance) from the constant-voltage power supply V2 through the body diode when the switching element S21 is cut off (hereinafter, “cutting off the switching element is abbreviated as“ off ”)”. pulse generating circuit 51, initializing waveform generating circuit 52 is connected scan pulse generating circuit 53 is commonly, path recovery power from the power and the scan electrodes _SC 1 to SC _n supplied to the scan electrodes _SC 1 to SC _n flows The switching element S22 is arranged in such a direction that current does not flow into the constant voltage power source V3 from the main discharge path through the body diode when the switching element S22 is off. Has been.

In this way, the initialization waveform generation circuit 52 generates the initialization waveform as described above. In the first half of the initialization period, the discharge start voltage is set from the voltage V _{i1 that is} lower than the discharge start voltage to the data electrodes D _{1 to} D _m . voltage _{V i2} exceeding, that generates a ramp waveform that rises gently toward the Vset, the second half of the initializing period, the discharge starting voltage from the voltage _{V i3} to be equal to or less than the discharge starting voltage with respect to sustain electrodes _SU 1 to SU _n A slope waveform that gradually falls toward the voltage V _i4 exceeding V i, that is, Vad is generated.

  The scan pulse generation circuit 53 includes switching elements S31 and S32 made of a generally known element that performs a switching operation such as a MOSFET, a constant voltage power source V4 having a voltage value Vscn, and a backflow prevention that prevents a current flowing into the constant voltage power source V4. Diode D31, capacitor C31, and IC31, which is a Scan IC that generates scanning pulse waveforms by outputting one of the powers input to the two input ports by switching. Yes.

In the address period, scanning is performed by sequentially applying a negative scan pulse to all the scan electrodes SC _{1 to} SC _n . Therefore, in the writing period, the switching element S31 is made conductive (hereinafter, the conduction of the switching element is abbreviated as “on”) and supplied from the constant voltage power supply V4 via the backflow prevention diode D31 and the switching element S31. The power of the voltage value Vscn is input to one input port of the IC 31. Also, the switching element S22 of the initialization waveform generating circuit 52 is turned on, and the power of the negative voltage value Vad supplied from the constant voltage power supply V3 via the switching element S22 is input to the other input port of the IC31. Then, one of the power and power supplied from the power and the constant-voltage power supply V3 supplied from the constant-voltage power supply V4 is selected by IC 31, are configured to be supplied to the scan electrodes SC ₁ to SC _n. That, IC 31 is the timing of applying the negative scan pulse power from the constant-voltage power supply V3, when the other switching operation to supply power from the constant-voltage power supply V4 to scan electrodes SC ₁ to SC _n .

Note that the switching element S32 is turned off in the writing period and turned on in the initialization period and the sustain period. This is because the same power is input to the two input ports of the IC 31 by turning on the switching element S32 so that the same power is supplied to the scan electrodes SC _{1 to} SC _n regardless of the switching state of the IC 31. It is to make it.

  Switching of the switching elements S1, S2, S5, S6, S21, S22, S31, S32 and the IC 31 is controlled based on the subfield control signal generated in the subfield processing circuit 3.

  Further, in order to electrically isolate sustain pulse generation circuit 51 from initialization waveform generation circuit 52, switching element S9 and switching element S9 are provided on the main discharge path between sustain pulse generation circuit 51 and initialization waveform generation circuit 52. S10 is inserted in series, and the body diodes are inserted in opposite directions (hereinafter referred to as “back-to-back connection”). With such a configuration, if switching elements S9 and S10 are simultaneously turned off, the current flowing from sustain pulse generating circuit 51 to initialization waveform generating circuit 52 and the initializing waveform generating circuit 52 to sustain pulse generating circuit 51 are switched. Any of the current flowing into the current can be cut off, and the sustain pulse generation circuit 51 can be electrically separated from the initialization waveform generation circuit 52.

  This is for preventing the influence of the constant voltage power source V1 of the sustain pulse generating circuit 51 having a lower potential when the power is supplied from the constant voltage power source V2 of the initialization waveform generating circuit 52, and When power is supplied from the constant voltage power supply V3 having a negative potential in the initialization waveform generation circuit 52, it is affected by a higher potential, that is, the ground potential of the sustain pulse generation circuit 51 (hereinafter abbreviated as “GND”). This is to prevent it from occurring.

  When power is supplied from the constant voltage power supply V2, there is a possibility that current flows from the constant voltage power supply V2 having the voltage value Vset to the constant voltage power supply V1 having a lower potential through the main discharge path. Since the potential of the path is lower than the potential Vset of the constant voltage power source V2, it becomes difficult to generate the original drive voltage waveform. Further, when power is supplied from the constant voltage power supply V3 having a negative voltage value Vad, current may flow from GND having a higher potential than the constant voltage power supply V3 to the constant voltage power supply V3 through the main discharge path. In this case, the potential of the main discharge path rises higher than the negative voltage value Vad of the constant voltage power supply V3, and it becomes difficult to generate the original drive voltage waveform.

However, in the initialization period in which driving is performed in the scan electrodes _SC 1 to SC _n by an initialization waveform generation circuit 52, by turning OFF the switching element S9, S10, initializing waveform generating circuit sustain pulse generating circuit 51 52 Can be electrically isolated from such a current flow. Therefore, during the period in which scan electrodes SC _{1 to} SC _n are driven by sustain pulse generation circuit 51, switching elements S 9 and S 10 are turned on to electrically connect sustain pulse generation circuit 51 to the main discharge path, In the initialization period or the like, switching elements S9 and S10 are turned off to electrically isolate sustain pulse generating circuit 51 from the main discharge path.

The period in which driving is performed in the scan electrodes SC ₁ to SC _n by sustain pulse generating circuit 51, main discharge of the constant-voltage power supply V3 potential is lower than the constant voltage source V2 and the GND potential is higher than the constant voltage power supply V1 Although it must be electrically isolated from the path, it can be done by turning off the switching elements S21, S22. This is because the switching element S21 is arranged so that the body diode of the switching element S21 is cut off from the current flowing from the constant voltage power supply V2 to the main discharge path, and the body diode of the switching element S22 is This is because the switching element S22 is arranged so as to cut off the current flowing from the main discharge path to the constant voltage power source V3.

The sustain pulse generating circuit 61 in the sustain electrode driving circuit 6 includes a constant voltage power source V5 having a voltage value Vsus, a coil L2, a recovery capacitor C2, switching elements S3 and S4, and backflow prevention diodes D3 and D4. and parts, they consist of a voltage clamp unit having a switching element S7, S8, PDP 10 of the capacitive load (sustain electrodes _SU 1 capacitive load generated in the to SU _n) and by resonating the coil L2, the recovery capacitor C2 The power is collected, but the operation is the same as that of the sustain pulse generation circuit 51, and thus the description is omitted.

  On the other hand, in the PDP, it is important to display an image in an easy-to-view manner as well as to reduce power consumption. Various proposals have been made regarding a technique for brightly displaying an image so that the image is easy to see.

  As a technique for brightly displaying an image, a technique for controlling the number of sustain pulses in the sustain period is disclosed. In this technique, the principle that a discharge cell appears brighter as the number of times of light emission generated in the sustain period is increased. For example, one field is changed from the first subfield to the eighth subfield (hereinafter referred to as the first subfield). (SF1), and the second subfield is abbreviated as “SF2”), the number of sustain pulses of SF1 is 1, the number of sustain pulses of SF2 is 2, and the following SF3 to SF8 When the number of sustain pulses is 4, 8, 16, 32, 64, 128, respectively, the number of sustain pulses from SF1 to SF8 is doubled to 2, 4, 8, 16, 32, 64, 128, 256, respectively. 2 times mode, 3 times mode in which the number of sustain pulses from SF1 to SF8 is tripled, 4 times mode in which the number of sustain pulses is quadrupled, and subfield sustain pulses. Is changed from 1 × to 2 ×, 3 ×, and 4 × (hereinafter, the magnification of the number of sustain pulses is abbreviated as “luminance magnification”) to control the number of times of light emission in the sustain period, thereby increasing the brightness of the screen. Can be adjusted. By using this technique, the average brightness (APL: Average Picture Level) of the image is detected, the luminance magnification is switched based on the detected APL, and when the APL is low, the luminance magnification is increased to increase the dark image. Can be displayed brighter (see, for example, Patent Document 2).

Or, by applying the phenomenon that the sustain discharge is strongly generated and the brightness is increased when the slope of the sustain pulse waveform is steep, the APL is detected and the driving time by the power recovery unit is controlled based on the detected APL, and the APL is low In the image, a technique for increasing the brightness by generating a strong sustain discharge by making the slope of the sustain pulse waveform steep is disclosed (for example, see Patent Document 3).
Japanese Examined Patent Publication No. 7-109542 JP-A-8-286636 JP 2001-184024 A

  According to the above-described technique, the maximum value of the brightness of the discharge cell (hereinafter referred to as “peak luminance”) is increased by increasing the number of sustain pulses in the sustain period or generating a strong sustain discharge by sharpening the sustain pulse waveform. The discharge cell can be brightly illuminated to display a dynamic image.

  However, according to the above-described technique, it is possible to brightly display the image by causing the discharge cell to emit light brightly. On the other hand, since the discharge cell emits light brightly, a dark region or the like in the image is also displayed brightly. Thus, a whitish image without black tightening, that is, an image with a so-called black floating may be displayed. In particular, when watching a movie or the like with a lot of dark scenes that frequently display dark images, there is a risk that the quality of the images will be lost if black floats.

  Or, when the surroundings of the plasma display device and the brightness of the displayed image are not balanced, such as when the surroundings are darkened and the plasma display device is viewed unnecessarily brightly, The displayed image may feel dazzling.

  In such a case, in the above-described prior art, brightness adjustment is performed by signal processing such as so-called contrast adjustment, and a black image or an image that does not feel dazzling is displayed. For example, in a plasma display device that displays an image with 1024 gradations from luminance values 0 to 1023, when the peak luminance is set to a luminance value 511 that is half of the maximum luminance value 1023 by contrast adjustment, the contrast is reduced by half, that is, the brightness is reduced by half. It is possible to display the selected image.

  However, in such brightness adjustment by contrast adjustment or the like, for example, by setting the peak luminance to a luminance value 511 that is half of the maximum luminance value 1023, image display is not performed with 512 gradations from luminance values 0 to 511. The gradation of the displayed image is impaired.

  The present invention has been made in view of such problems, and by controlling the impedance in the discharge path, the discharge current flowing through the discharge path during the sustain discharge is controlled, and the brightness is obtained without impairing the gradation. An object of the present invention is to provide a PDP driving circuit and a plasma display device capable of displaying an image with reduced noise.

  In order to achieve such an object, the PDP driving circuit of the present invention drives a plasma display panel having a plurality of scan electrodes and sustain electrodes constituting a display electrode pair to generate a sustain discharge in the display electrode pair. A drive circuit is characterized in that the impedance from a circuit provided for generating a sustain discharge to a scan electrode or a sustain electrode is variable.

  According to this configuration, the discharge current flowing during the sustain discharge is controlled by changing the impedance in the path from the circuit provided in the PDP drive circuit to the scan electrode or the sustain electrode in order to generate the sustain discharge, An image with reduced brightness can be displayed without impairing gradation.

  The PDP driving circuit drives the PDP by applying voltages having different driving waveforms to the scan electrode and the sustain electrode of the PDP in each period of the subfield having the initialization period, the address period, and the sustain period. A scan electrode drive circuit connected to the electrodes and a sustain electrode drive circuit connected to the sustain electrodes, the scan electrode drive circuit and the sustain electrode drive circuit in each sustain period of a plurality of subfields constituting one field A sustain pulse generation circuit for generating a sustain pulse to be applied to the scan electrode or the sustain electrode may be provided, and the impedance from the sustain pulse generation circuit to the scan electrode or the sustain electrode may be variable.

  According to this configuration, by changing the impedance in the discharge path, which is the path from the sustain pulse generating circuit to the scan electrode or the sustain electrode, the discharge current flowing through the discharge path during the sustain discharge is controlled, and the gradation is improved. An image with reduced brightness can be displayed without loss.

  The scan electrode driving circuit is provided between the sustain pulse generating circuit and the scan electrode and generates an initializing waveform to be applied to the scan electrode during the initializing period, and the sustain pulse generating circuit is initialized. A switching circuit provided between the waveform generation circuit and electrically separating the initialization waveform generation circuit and the sustain pulse generation circuit; You may comprise so that the impedance to a scanning electrode may be made variable. According to this configuration, the impedance in the discharge path can be made variable by making the impedance in the switch circuit provided for electrically separating the initialization waveform generating circuit and the sustain pulse generating circuit variable.

  Further, the switch circuit is maintained from the first switch and the initialization waveform generation circuit configured by a plurality of switching elements connected in parallel that can cut off a current flowing from the sustain pulse generation circuit to the initialization waveform generation circuit. And a second switch constituted by a plurality of switching elements connected in parallel capable of interrupting a current flowing to the pulse generation circuit, and the plurality of those constituting the first switch and the second switch You may comprise so that the impedance in a switch circuit may be made variable by selectively turning on a switching element. According to this configuration, the initialization waveform generation circuit and the sustain pulse generation circuit can be electrically separated by simultaneously turning off the first switch and the second switch, and further, the first switch The impedance in the switch circuit can be made variable by selectively conducting a plurality of switching elements connected in parallel constituting the second switch.

  The sustain pulse generation circuit is connected in parallel with a power recovery unit that recovers the power accumulated in the capacitive load of the electrode of the PDP in a recovery capacitor by LC resonance and reuses the recovered power for driving the PDP. A power supply clamp switch configured by a plurality of switching elements to clamp the electrode of the PDP to the power supply potential, and a ground clamp switch configured by a plurality of switching elements connected in parallel to clamp the electrode of the PDP to the ground potential; A plurality of switching elements constituting the power clamp switch and the ground clamp switch are selectively turned on to vary the impedance in the power clamp switch and the ground clamp switch, thereby causing the scan pulse or Maintenance power The impedance to be configured to be variable. According to this configuration, the impedance in the power clamp switch or the ground clamp switch is varied by selectively conducting a plurality of switching elements connected in parallel that respectively form the power clamp switch and the ground clamp switch, thereby discharging. The impedance in the path can be made variable.

  Further, the sustain pulse generating circuit included in the scan electrode driving circuit includes a power recovery coil and a scan that recover LC in the recovery capacitor as recovered power by causing LC resonance with the capacitive load of the scan electrode. A power recovery unit having a power supply coil for supplying the recovered power stored in the recovery capacitor by LC resonance with the capacitive load of the electrode as supply power to the capacitive load of the scan electrode, and one end connected to the power supply potential and the scan electrode A power supply clamp switch for clamping the power supply potential to the power supply potential and a clamp portion having a ground clamp switch for clamping the scan electrode to the ground potential, and the other end of the power supply clamp switch is connected in series with the power supply clamp switch and the power supply potential via the power supply clamp switch To multiple switching elements connected in parallel that can cut off the current flowing to The switch circuit is configured to vary the impedance in the switch circuit by selectively conducting a plurality of switching elements constituting the switch circuit, thereby varying the impedance from the sustain pulse generating circuit to the scan electrode. You may comprise as follows. According to this configuration, by turning off all of the plurality of switching elements constituting the switch circuit, it is possible to cut off the current flowing into the power supply potential via the power supply clamp switch. By selectively conducting, the impedance in the path for supplying current from the recovery capacitor to the scan electrode can be varied, thereby making the impedance in the discharge path variable.

  In addition, the switch circuit may be configured by connecting in parallel at least one switching element and at least one diode arranged in a direction to cut off the current flowing to the power clamp switch. According to this configuration, the impedance in the path for supplying current from the recovery capacitor to the scan electrode can be varied depending on whether the switching element is turned on or not.

  The scan electrode driving circuit has a scan pulse generation circuit that generates a scan pulse to be applied to the scan electrode in the address period, and the scan pulse generation circuit has different voltage values in order to generate the scan pulse in the address period. It has a plurality of switching elements that can switch the constant voltage power source and apply it to the scan electrodes and change the passage path of the sustain pulse in the sustain period, and maintain by selectively conducting the plurality of switching elements in the sustain period It is also possible to change the pulse passage path, thereby making the impedance from the sustain pulse generating circuit to the scan electrode variable. According to this configuration, the plurality of switching elements included in the scan pulse generation circuit are selectively turned on in the sustain period to change the sustain pulse passage path, and the sustain pulse passes through a smaller number of switching elements. When passing through a large number of switching elements, switching is performed when passing through the switching elements in parallel. Thereby, the impedance in the discharge path can be made variable.

  In addition, the plasma display device of the present invention is arranged in parallel to the first substrate with a plurality of scan electrodes and sustain electrodes arranged in parallel on the first substrate and constituting the display electrode pair, with the discharge space interposed therebetween. A PDP having a plurality of data electrodes arranged on a second substrate in a direction intersecting with the scanning electrodes and forming a discharge cell with a display electrode pair, and any of the PDP driving circuits described above Features. According to this configuration, the impedance in the discharge path from the sustain pulse generating circuit to the scan electrode or the sustain electrode can be made variable to control the discharge current flowing through the discharge path during the sustain discharge, without impairing the gradation. A plasma display device capable of displaying an image with reduced brightness can be configured.

  According to the present invention, the PDP drive circuit can control the discharge current during the sustain discharge by controlling the impedance in the discharge path, thereby displaying an image with reduced luminance without impairing the gradation. In addition, a plasma display device can be provided.

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

(Embodiment 1)
FIG. 1 is a circuit diagram of a PDP drive circuit according to Embodiment 1 of the present invention. The structure and electrode arrangement of the PDP 10 to be driven by the PDP drive circuit in the present embodiment are the same as those of the PDP 10 shown in FIGS. 9 and 10, and the PDP drive circuit in the present embodiment is the PDP 10 Each drive voltage waveform applied to each electrode is the same as the drive voltage waveform shown in FIG. 11, and the electrical configuration of the plasma display apparatus incorporating the PDP drive circuit and PDP 10 in this embodiment is shown in FIG. Since it is the same as the block diagram of the electrical configuration shown, a description of each configuration and operation is omitted.

As shown in FIG. 1, the PDP drive circuit according to the first embodiment of the present invention includes a scan electrode drive circuit 501 provided with a power recovery circuit and a sustain pulse generation circuit 61. The scan electrode drive circuit 501 includes a sustain pulse generation circuit 511. And an initialization waveform generation circuit 52, a scan pulse generation circuit 53, and a switch circuit composed of switching elements S9 ₁ , S9 ₂ , S10 ₁ , S10 ₂ .

  The sustain pulse generation circuit 511 includes a constant voltage power source V1 having a voltage value Vsus, a power recovery unit, and a voltage clamp unit. The power recovery unit is a coil L1, a recovery capacitor C1, switching elements S1 and S2, and a backflow prevention unit. Diodes D1 and D2 are provided. The voltage clamp section includes a switching element S5 that is a power clamp switch and a switching element S6 that is a ground clamp switch.

In sustain pulse generation circuit 511, the power recovery unit and the voltage clamp unit are switched by switching switching elements S1, S2, S5, and S6, and a sustain pulse to be applied to scan electrodes SC _{1 to} SC _n is generated. . In the power recovery unit, by using the coil L1 which is an inductance element, LC resonance is caused between the capacitive load of the PDP 10 (capacitive load generated in the scan electrodes SC _{1 to} SC _n in FIG. 10) and the inductance of the coil L1, Collect and supply power. The voltage clamping unit clamps the scan electrodes _SC 1 to SC _n and supplies power to the scan electrodes _SC 1 to SC _n from the constant-voltage power supply V1 voltage value Vsus through the switching elements S5 to the voltage value Vsus, also, by clamping to the ground potential scan electrodes _SC 1 to SC _n via the switching element S6, to drive the scan electrodes _SC 1 to SC _n.

The initialization waveform generating circuit 52 includes switching elements S21 and S22 made of generally known elements that perform a switching operation such as a MOSFET, a constant voltage power supply V2 having a voltage value Vset having a higher potential than the constant voltage power supply V1, and a negative voltage And a constant voltage power supply V3 having a voltage value Vad. Then, supplies power to the scan electrodes _SC 1 to SC _n from the constant-voltage power supply V2 through the switching element S21, also, a negative potential to the scan electrodes _SC 1 to SC _n from the constant-voltage power supply V3 via the switching element S22 Is supplied to generate an initialization waveform. The switching element S21 is arranged in such a direction that its body diode cuts off the current flowing from the constant voltage power supply V2 to the main discharge path, and the switching element S22 is the current flowing from the main discharge path to the constant voltage power supply V3 by the body diode. It is arranged in the direction to shut off.

Then, in the first half of the initialization period, the initialization waveform generation circuit 52 proceeds from the voltage V _{i1 that is} equal to or lower than the discharge start voltage to the voltage V _i2 that exceeds the discharge start voltage, that is, Vset with respect to the data electrodes D _{1 to} D _m . generating a ramp waveform that gradually rises, in the latter half of the initializing period, voltage V _i4 exceeding the discharge start voltage from the voltage V _i3 to be equal to or less than the discharge starting voltage with respect to sustain electrodes SU ₁ to SU _n, i.e. towards the Vad generates a gradient waveform gradually decreasing Te, applied to scan electrodes _SC 1 to SC _n.

The scan pulse generation circuit 53 includes switching elements S31 and S32 made of a generally known element that performs a switching operation such as a MOSFET, a constant voltage power source V4 having a voltage value Vscn, and a backflow prevention that prevents a current flowing into the constant voltage power source V4. Diode D31, capacitor C31, and IC 31 that performs a switching operation. A negative scan pulse is generated in the address period and sequentially applied to scan electrodes SC _{1 to} SC _n .

The sustain pulse generating circuit 61, the same operation as sustain pulse generating circuit 511, PDP 10 of the capacitive load (capacitive load generated in the sustain electrodes _SU 1 to SU _n in FIG. 10) and the inductance of the coil L2 perform recovery and supply of electric power by LC resonance, and drives the sustain electrodes _SU 1 to SU _n.

  Switching of these switching elements S 1, S 2, S 5, S 6, S 21, S 22, S 31, S 32 and IC 31 is controlled based on a subfield control signal created in the subfield processing circuit 3.

Further, in order to electrically isolate sustain pulse generation circuit 511 from initialization waveform generation circuit 52, a body diode is maintained on the main discharge path between sustain pulse generation circuit 511 and initialization waveform generation circuit 52. a first switch including a pulse generating circuit 511 reset waveform generating circuit 52 a switching element S9 ₁ and S9 ₂ connected in parallel with each other are arranged such that the direction of interrupting the flow of current to the initialization body diode configuration and a second switch comprising a waveform generating circuit 52 from the sustain pulse generating circuit 511 is arranged such that the direction of interrupting the flow of current to the connected in parallel with each other on the switching elements S10 ₁ and S10 ₂ are connected in series A switched circuit is inserted. Thus, if off the switching element S9 ₁ and S9 ₂ and the switching element S10 ₁ and S10 ₂ simultaneously, the current flowing from the sustain pulse generating circuit 511 to the reset waveform generation circuit 52, the initializing waveform generating circuit 52 Any of the current flowing to sustain pulse generating circuit 511 can be cut off, and sustain pulse generating circuit 511 can be electrically separated from initialization waveform generating circuit 52.

The switching elements S9 ₁ , S9 ₂ , S10 ₁ , S10 ₂ can be independently controlled on / off. Further, in the first embodiment of the present invention, in the main discharge path to the case of turning on the switching element S9 ₁ and S10 _1, and if you turn on the switching element _{S9 1,} S9 2, S10 ₁ and S10 ₂ in The impedance is different.

  The inventor has found through experiments that there is a relationship between the discharge current flowing during the sustain discharge and the light emission luminance due to the sustain discharge. That is, it was found that by limiting the discharge current, the intensity of discharge can be suppressed and the light emission luminance can be suppressed. It was found that the discharge current flowing during the sustain discharge can be controlled by making the impedance of the main discharge path variable. Furthermore, in the experiments conducted by the present inventors, it was found that when the impedance in the main discharge path is increased by 22 mΩ, the emission luminance due to the sustain discharge is reduced by 10%, and when the impedance is increased by 100 mΩ, the emission luminance is reduced by 50%.

Therefore, in the first embodiment of the present invention, when the switching elements S9 ₁ and S10 ₁ are turned on, the combined impedance of the switching diodes S9 ₁ and S10 ₁ and the switching elements S9 ₂ and S10 _{2 by} the body diode, and the switching element _{S9 1,} S9 2, S10 ₁ and S10 ₂ switching element _S9 1 when you _turn, S9 2, S10 ₁ and S10 the switching element _S9 1 as the difference between the combined impedance due ₂ is 100 m [Omega, _S9 2, S10 ₁ and S10 ₂ are provided. Then, on in the sustain period, when displaying the normal image is all on the switching element _{S9 1, S9 2,} S10 1 and S10 _2, only the switching element S9 ₁ and S10 ₁ when displaying an image with reduced brightness Then, sustain pulse generation circuit 511 drives scan electrodes SC _{1 to} SC _n .

Thus, if you turn on only the switching element S9 ₁ and S10 ₁ is, 100 m [Omega impedance in the main discharge path as compared with the case of turning on all the switching elements _{S9 1, S9 2,} S10 1 and S10 ₂ The discharge current in the sustain discharge in the discharge cell can be limited to reduce the light emission luminance by 50%, that is, an image with the peak luminance reduced by 50% can be displayed.

  In the brightness adjustment according to the first embodiment of the present invention, unlike the brightness adjustment by signal processing such as contrast adjustment, the peak brightness is lowered by suppressing the light emission brightness in the discharge cell. It becomes possible to display an image without impairing the performance.

  As described above, according to the first embodiment of the present invention, the switch circuit that is inserted on the main discharge path in order to electrically isolate sustain pulse generation circuit 511 from initialization waveform generation circuit 52 is connected in parallel. A plurality of switching elements are connected by back-to-back connection, and the impedance in the main discharge path can be switched by a combination of switching elements to be turned on. When it is desired to display an image brightly, all the switching elements constituting the switch circuit are turned on to lower the impedance in the main discharge path, and a sustain discharge is generated in the discharge cell without limiting the discharge current. . If you want to display an image with reduced brightness, you can selectively turn on the switching elements that make up the switch circuit to increase the impedance in the main discharge path and generate a sustain discharge that limits the discharge current. Lower. As a result, it is possible to display an image with reduced brightness without impairing the gradation, for example, when viewing a movie with many dark scenes or viewing with a dark surrounding of the plasma display device. This makes it possible to display a black-tight image with reduced roughness without impairing the gradation.

  In the first embodiment of the present invention, it has been explained that the peak luminance is reduced by 10% when the impedance in the main discharge path is increased by 22 mΩ, and the peak luminance is reduced by 50% when the impedance is increased by 100 mΩ. Only numerical values based on the results of experiments conducted by the present inventors are shown, and the present invention is not limited to these numerical values. Since these values vary depending on the characteristics of the PDP and the characteristics of the drive circuit, an experiment was conducted to determine the relationship between the light emission luminance and impedance of the PDP used in the plasma display device. It is desirable to set a correct value.

In the first embodiment of the present invention has been described configuration is turned on only the switching element S9 ₁ and S10 ₁ to increase the impedance in the main discharge path, for example, scan electrodes SC ₁ to SC from the recovery capacitor C1 when power supply to _n, so that electric power is supplied to turn on only the switching element S9 ₁ through a switching element S9 ₁ and the switching element _S10 1, S10 ₂ of the body diode, the scan electrodes _SC 1 to SC _n from the time of power recovery to the recovery capacitor C1, may be power through a switching element S10 ₁ and the switching element S9 _1, S9 ₂ of the body diode is turned on only the switching element S10 ₁ is recovered. Even with such a configuration, the impedance in the main discharge path can be increased.

Further, in FIG. 1, the is shown the switching element _{S9 1,} S9 2, S10 ₁ and S10 ₂ as one switching element, respectively, which indicated for convenience respectively for the sake of clarity as a single switching element However, it is desirable to configure each switching element with an optimal number of elements based on the rating of the switching elements used, the maximum current that flows during driving, and the like.

  In the first embodiment of the present invention, a configuration in which the combined impedance in the switch circuit can be switched in two stages to switch between image display with normal light emission luminance and image display with light emission luminance reduced by 50% will be described. However, the present invention is not limited to this configuration, and a switch circuit may be configured so that the combined impedance can be switched in three steps or more so that the suppression of the emission luminance can be switched more finely.

(Embodiment 2)
In the first embodiment of the present invention, as shown in FIG. 1, in the switch circuit provided to electrically isolate sustain pulse generation circuit 511 from initialization waveform generation circuit 52, the combined impedance is switched to discharge current. The configuration for limiting the above has been described. However, the discharge current can be limited by switching the impedance, for example, by a power clamp switch and a ground clamp switch in the voltage clamp unit in the sustain pulse generation circuit.

  FIG. 2 is a circuit diagram of a PDP drive circuit according to Embodiment 2 of the present invention. The main part of the PDP drive circuit in the present embodiment that is different from the PDP drive circuit shown in the first embodiment is the configuration of the power clamp switch and the ground clamp switch in the voltage clamp unit. The explanation will be focused on these parts.

  As shown in FIG. 2, the PDP drive circuit according to the second embodiment of the present invention includes scan electrode drive circuit 502 and sustain pulse generation circuit 62 that include a power recovery circuit, and scan electrode drive circuit 502 includes sustain pulse generation circuit 512. And an initialization waveform generation circuit 52, a scan pulse generation circuit 53, and a switch circuit composed of switching elements S9 and S10.

Sustain pulse generating circuit 512 is composed of a constant-voltage power supply V1 and the power recovery unit and the voltage clamp portion of the voltage value Vsus, voltage clamp unit, a power supply clamp constituted by a switching element S5 _1, S5 ₂ connected in parallel A switch and a ground clamp switch configured by switching elements S6 ₁ and S6 ₂ connected in parallel are provided.

The sustain pulse generating circuit 62 is composed of a constant-voltage power supply V5 and the power recovery unit and the voltage clamp portion of the voltage Vsus, the voltage clamp unit, constituted by a switching element S7 _1, S7 ₂ connected in parallel A power clamp switch and a ground clamp switch configured by switching elements S8 ₁ and S8 ₂ connected in parallel are provided.

Then, the sustain pulse generating circuit 512, is applied to the switching elements _{S1, S2, S5 1, S5} 2, S6 1, S6 scan electrodes _SC 1 switches the power recovery unit and the voltage clamp unit by switching the ₂ to SC _n generates a sustain pulse for sustain the pulse generating circuit 62, the switching elements _{S3, S4, S7 1, S7} 2, S8 1, S8 2 sustain switch the power recovery unit and the voltage clamp unit by switching electrodes SU ₁ generating a sustain pulse to be applied to to SU _n.

The switching elements S5 ₁ , S5 ₂ , S6 ₁ , S6 ₂ and the switching elements S7 ₁ , S7 ₂ , S8 ₁ , S8 ₂ can be independently controlled on / off, for example, from the constant voltage power supply V1 to the scanning electrode when supplying power to the SC ₁ to SC _n, you checked only switching element S5 ₁ and the switching element S5 _1, S5 ₂ in the case of on, the path of current for discharging flow discharge The impedance in the path is made different. Similarly, when supplying power to the sustain electrodes _SU 1 to SU _n from the constant-voltage power supply V5, in the case of turning on the switching element _S7 1, S7 ₂ if you turn on only the switching element S7 _1, discharge The impedance in the path is made different. Furthermore, in the case of releasing the power to the ground potential from the scan electrodes SC ₁ to SC _n, the impedance in the discharge path in the case where the ON and the switching element S6 _1, S6 ₂ you checked only switching element S6 ₁ to be different, in the case of releasing the power to the ground potential from the sustain electrode SU ₁ to SU _n, the discharge path in the case of turning on the switching element S8 _1, S8 ₂ if you turn on only the switching element S8 ₁ Impedance is different.

When displaying a normal image, the clamping operation is performed by the switching operation by the switching elements S5 ₁ , S5 ₂ , S6 ₁ , S6 ₂ , S7 ₁ , S7 ₂ , S8 ₁ and S8 ₂ in order to reduce the impedance in the discharge path. done was to perform the clamping operation by the switching operation of the switching element S5 _1, S6 _1, S7 1 and S8 ₁ in order to increase the impedance in the discharge path when an image is displayed with reduced brightness.

Thus, in the switching operation by the switching elements S5 ₁ , S6 ₁ , S7 ₁ and S8 ₁ , the switching operation by the switching elements S5 ₁ , S5 ₂ , S6 ₁ , S6 ₂ , S7 ₁ , S7 ₂ , S8 ₁ and S8 ₂ The impedance in the discharge path can be increased as compared with the above, and the discharge current in the sustain discharge in the discharge cell can be limited to reduce the light emission luminance and display an image with reduced brightness.

  As described above, according to the second embodiment of the present invention, the power clamp switch and the ground clamp switch of the voltage clamp unit in the sustain pulse generation circuit are configured by the plurality of switching elements connected in parallel, and the switching operation is performed. The impedance in the discharge path can be switched by a combination of switching elements. When it is desired to display an image brightly, the impedance in the discharge path is lowered by the switching operation of all the switching elements constituting the power clamp switch and the ground clamp switch, and the discharge current is not limited and maintained in the discharge cell. Generate a discharge. In addition, when you want to display images with reduced brightness, the switching elements that make up the power clamp switch and ground clamp switch are selectively switched to increase the impedance in the discharge path, and sustain discharge with limited discharge current. To reduce the luminance. As a result, it is possible to display an image with reduced brightness without impairing the gradation, for example, when viewing a movie with many dark scenes or viewing with a dark surrounding of the plasma display device. This makes it possible to display a black-tight image with reduced roughness without impairing the gradation.

In FIG. 2, since the switching element _{S5 1, S5 2, S6 1} , S6 2, S7 1, S7 2, S8 are shown _first and S8 ₂ as one switching element each, which is to clarity For convenience, each is shown as a single switching element, and it is desirable to configure each switching element with the optimum number of elements based on the rating of the switching element used, the maximum current that flows during driving, and the like.

  Further, in the second embodiment of the present invention, the configuration in which the impedances of the power clamp switch and the ground clamp switch are switched in two stages has been described. However, the present invention is not limited to this configuration, and the impedance is divided into three stages or more. A power clamp switch and a ground clamp switch may be configured so as to be switched, and the suppression of the emission luminance may be switched more finely.

Further, the second embodiment of the present invention uses all of the switching elements S5 ₁ , S5 ₂ , S6 ₁ , S6 ₂ , S7 ₁ , S7 ₂ , S8 ₁ and S8 ₂ constituting the power clamp switch and the ground clamp switch. is not limited to the configuration to switch the impedance and, some of them switching element, for example, a configuration in which using only the switching element S5 ₁ and S5 _2, the switching element _{S5 1, S5 2,} S8 1 and S8 ₂ may be performed to switch the impedance equal to configurations using.

(Embodiment 3)
In the first embodiment of the present invention, as shown in FIG. 1, the example in which the coil for LC resonance in the power recovery unit is configured only by the coil L1 has been described. However, the embodiment of the present invention is not limited to this configuration. For example, in order to change the resonance frequency between when power is recovered and when it is supplied, the coil of the power recovery unit is divided into two. It is possible to apply. In the third embodiment of the present invention, an example of this configuration will be described.

  FIG. 3 is a circuit diagram of a PDP drive circuit according to Embodiment 3 of the present invention. Note that the main part of the PDP drive circuit in this embodiment that is different from the PDP drive circuit shown in Embodiment 1 is the configuration of the sustain pulse generation circuit, and therefore, here, the description will focus on the different main parts. Do.

  As shown in FIG. 3, the PDP drive circuit according to the third embodiment of the present invention includes scan electrode drive circuit 503 having a power recovery circuit and sustain pulse generation circuit 61, and scan electrode drive circuit 503 has a sustain pulse generation circuit. 513, an initialization waveform generation circuit 52, a scan pulse generation circuit 53, and a switch circuit including a switching element S9.

The sustain pulse generation circuit 513 includes a constant voltage power source V1 having a voltage value Vsus, a power recovery unit, and a voltage clamp unit. The voltage clamp unit includes a switching element S5 that is a power clamp switch and a switching element S6 that is a ground clamp switch. And. The power recovery unit includes a coil L1A that is a power supply coil, a coil L1B that is a power recovery coil, a recovery capacitor C1, switching elements S1 and S2, and backflow prevention diodes D1 and D2. With this configuration, power recovered from the capacitive load of the PDP 10 to the recovery capacitor C1 passes through the coil L1B, and power supplied from the recovery capacitor C1 to the capacitive load of the PDP 10 passes through the coil L1A. The circuit 513 can be driven by changing the resonance frequency between when power is recovered and when it is supplied. Further, sustain pulse generating circuit 513 is connected in parallel to each other and is connected in series with switching element S5 with a contact with coil L1A interposed therebetween, and is arranged in such a direction as to cut off the current that the body diode flows into constant voltage power supply V1. and a switching element _S10 1, S10 ₂ was.

On the main discharge path between sustain pulse generation circuit 513 and initialization waveform generation circuit 52, the body diode is arranged in a direction to block the current flowing from sustain pulse generation circuit 513 to initialization waveform generation circuit 52. A switching circuit composed of the switching element S9 is inserted. Since the body diode of the switching element S6 is arranged so as to cut off the current flowing from the main discharge path to the ground potential, and the body diode of the switching element S2 is arranged so as to cut off the current flowing into the recovery capacitor C1, respectively. if element S2, S6, S9, S10 ₁ and S10 ₂ off simultaneously, the current flowing from the sustain pulse generating circuit 513 to the reset waveform generation circuit 52, flows from the initialization waveform generating circuit 52 to the sustain pulse generating circuit 513 Any of the currents can be cut off, and sustain pulse generation circuit 513 can be electrically isolated from initialization waveform generation circuit 52.

The switching elements S10 ₁ and S10 ₂ can be independently turned on / off, and when only the switching element S10 ₁ is turned on and when the switching elements S10 ₁ and S10 ₂ are turned on, It is comprised so that the impedance in a discharge path may differ.

That is, in the third embodiment of the present invention, when displaying a normal image, the switching elements S10 ₁ and S10 ₂ are turned on to reduce the impedance in the discharge path, and when displaying an image with reduced brightness, the switching element S10 by increasing the impedance at ₁ only is turned on discharge path, thereby to sustain pulse generating circuit 513 perform the driving of the scan electrodes _SC 1 to SC _n.

Thus, when you turn on only the switching element S10 _1, since the impedance becomes large in the discharge path than when you turn on the switching element S10 _1, S10 _2, to limit the discharge current in the sustain discharge in the discharge cells It is possible to display an image with reduced brightness and reduced brightness.

  As described above, according to the third embodiment of the present invention, the sustain pulse is generated in the sustain pulse generation circuit 513 in which the coil of the power recovery unit is divided into two to change the resonance frequency between when the power is recovered and when the power is recovered. In order to electrically isolate the generation circuit 513 from the initialization waveform generation circuit 52, a plurality of switching elements arranged in a direction to block the current flowing into the constant voltage power source V1 by the body diode are connected in parallel and connected to the coil L1. Provided in series with the switching element S5 with the contacts in between. And it is comprised so that the impedance in a discharge path can be switched by the combination of the switching element to turn on. If you want to display an image brightly, turn on all of the switching elements connected in parallel to lower the impedance in the discharge path, and generate a sustain discharge in the discharge cell without limiting the discharge current. Let If you want to display images with reduced brightness, you can selectively turn on multiple switching elements connected in parallel to increase the impedance in the discharge path and generate a sustain discharge that limits the discharge current. Reduce the brightness. As a result, it is possible to display an image with reduced brightness without impairing the gradation, for example, when viewing a movie with many dark scenes or viewing with a dark surrounding of the plasma display device. This makes it possible to display a black-tight image with reduced roughness without impairing the gradation.

In the third embodiment of the present invention, the configuration in which the impedance in the discharge path is switched in two stages by the combination of the switching elements S10 ₁ and S10 ₂ to be turned on is not limited to this configuration. May be configured by a plurality of switching elements so as to be switched in three stages or more so that the degree of suppression of light emission luminance can be switched more finely.

Further, in Embodiment 3 of the present invention has been described a configuration of connecting the switching element _S10 1, S10 ₂ in parallel, for example, a diode D10 in place of the switching element S10 _2, the switching element S10 ₁ and the diode D10 The same effect can be obtained even in a configuration in which the two are connected in parallel.

FIG. 4 is a circuit diagram of another example of the PDP drive circuit according to Embodiment 3 of the present invention. The PDP drive circuit shown in FIG. 4 includes a scan electrode drive circuit 504 including a power recovery circuit and a sustain pulse generation circuit 61. The scan electrode drive circuit 504 includes a sustain pulse generation circuit 514, an initialization waveform generation circuit 52, It has a scan pulse generation circuit 53 and a switch circuit composed of a switching element S9. PDP drive circuit and different parts shown in the PDP driving circuit 3 shown in FIG. 4, in the sustain pulse generating circuit 514, in that a diode D10 in place of the switching element S10 ₂ of sustain pulse generating circuit 513. At this time, the diode D10 is disposed in a direction to shut off the current flowing to the body diode as well as the constant-voltage power supply V1 of the switching element S10 _1. Thus, in the initialization period and the write period, it is possible to interrupt a current by turning off the switching element S10 ₁ flows into the constant-voltage power supply V1. Then, in the sustain period, the switching element S10 ₁ When off, the impedance of the coil L1A to the switching element (S9) is turned combined impedance due to the diode D10 and switching element S10 ₁ body diode, turn on the switching element S10 ₁ Impedance can be made larger than that. Thereby, the effect similar to the above can be acquired.

3 and 4, each of the switching elements S10 ₁ and S10 ₂ is shown as one switching element, and the diode D10 is shown as one diode. However, for the sake of clarity, each of the switching elements S10 ₁ and S10 ₂ is shown as one switching element. It is only shown as an element, and it is desirable to configure each with an optimum number of elements based on the rating of the element to be used, the maximum current that flows during driving, and the like.

  Further, in the third embodiment of the present invention, in the switching element S9, the switching element S9 is formed by a plurality of switching elements connected in parallel to each other as shown in the first embodiment, and the combination of switching elements to be turned on A configuration in which the impedance is switched by the above may be further added.

In the first to third embodiments of the present invention, the sustain pulse passage path is changed by selectively conducting the IC 31 and the switching elements S31 and S32 which are Scan ICs in the scan pulse generation circuit 53, and Thereby, it can also be set as the structure which switches the impedance in a discharge path | route. FIG. 5 is a circuit diagram of scan pulse generation circuit 53 in the embodiment of the present invention. As shown in FIG. 5, the inside of the IC 31 is configured by connecting switching elements S41 and S42 in series, the other end of the switching element S41 is connected to a connection point between the switching elements S31 and S32, and the switching element S42. Is connected to the main discharge path. The connection point between the switching elements S41 and S42 are PDP10 electrodes, are connected to the scan electrodes _SC 1 to SC _n. The switching element S41 is in the direction in which the body diode to shut off the flow current through the switching element S31, S32 is to scan electrodes _SC 1 to SC _n, the switching element S42 is the body diode scan electrodes _SC 1 ~ It is arranged in such a direction as to cut off the current flowing from _SCn to the main discharge path. By switching on switching elements S41 and S42, power flows from switching element S31 or S32 and flows from the main discharge path. It is possible to supply the scan electrodes SC ₁ to SC _n by switching the electric power. In such a configuration, the switching element S31, S32, S41 and S42 are switched on to change the sustain pulse passage path, and the number of switching elements through which the sustain pulse passes is changed to change the sustain pulse from the sustain pulse generation circuit. The impedances of scan electrodes SC _{1 to} SC _n can be changed.

For example, when the switching element S42 is turned on, the switching element in the scan pulse generation circuit 53 through which the sustain pulse passes is only the switching element S42, and the impedance at that time is due to the switching element S42. Also, turning off the switching element S42, according to the main discharge path for power through the body diode in the scan electrodes SC ₁ to SC _n switching element S42 is supplied from the impedance at that time the body diode of the switching element S42 It will be a thing. Alternatively, when the switching element S42 is turned off and the switching element S41 is turned on, the impedance at that time is the impedance of the switching element S32 or the series circuit of the body diode of the switching element S32 and the switching element S41 and the body diode of the switching element S42. The combined impedance is parallel to the impedance due to. Thus, in the sustain period, by selectively turning on the plurality of switching elements S31, S32, S41, and S42 provided in the scan pulse generation circuit 53, the path through which the sustain pulse passes is changed. Thus, the impedance in the discharge path can be made variable.

  In FIG. 5, each of the switching elements S31, S32, S41, and S42 is shown as one switching element. However, this is only shown as one switching element for convenience in order to make the drawing easy to see. It is desirable to configure each switching element with an optimum number of elements based on the rating of the switching element to be operated and the maximum current that flows during driving.

  FIG. 5 shows an example in which no resistor is inserted on the wiring connecting the switching element S31 and the switching element S41. However, the present invention is not limited to this configuration. For example, a resistor is inserted there. For example, the variable width of the impedance may be further increased.

In the third embodiment from the first embodiment of the present invention, each includes a sustain pulse generating circuit to the scanning electrode driving circuit and the sustain electrode driving circuit, the scan electrodes SC ₁ to SC _n and sustain electrodes SU ₁ to SU _n In the above description, the sustain pulse is alternately applied to generate the sustain discharge. However, the present invention is not limited to this configuration. For example, even in a circuit configuration in which a sustain pulse is applied only to scan electrodes SC _{1 to} SC _n to generate a sustain discharge, the embodiment of the present invention is not limited. It is possible to apply the configuration for varying the impedance shown in the first to third embodiments.

FIG. 6 is a circuit diagram showing another example of the PDP drive circuit according to Embodiment 1 of the present invention. The PDP drive circuit shown in FIG. 6 includes a scan electrode drive circuit 506. The scan electrode drive circuit 506 includes a sustain pulse generation circuit 516, an initialization waveform generation circuit 52, a scan pulse generation circuit 53, and switching elements S9 ₁ and S9 _2. , S10 ₁ and S10 ₂ . The initialization waveform generation circuit 52, the scan pulse generation circuit 53, and the switch circuit have the same configuration as the PDP drive circuit shown in FIG. 1 and perform the same operation.

Sustain pulse generating circuit 516 is composed of a constant-voltage power supply V11 and the voltage clamp portion of the constant-voltage power supply V1 and a negative voltage value of the voltage value Vsus (-Vsus), the voltage clamp unit, the scan electrodes _SC 1 to SC _n A switching element S5 for clamping to the potential of the constant voltage power supply V1 and a switching element S6 for clamping to the negative potential of the constant voltage power supply V11 are provided. Further, in the PDP driving circuit shown in FIG. 6, the sustain electrodes _SU 1 to SU _n is connected to the ground potential.

Then, a sustain pulse having an amplitude of Vsus is applied to scan electrodes SC _{1 to} SC _n from the voltage value (−Vsus) generated by sustain pulse generation circuit 516, so that the potentials of scan electrodes SC _{1 to} SC _n are (−Vsus). ) To Vsus or Vsus to (−Vsus) to generate a sustain discharge.

For example, even in such a configuration shown in FIG. 6, by selectively turning on switching elements S9 ₁ , S9 ₂ , S10 ₁ and S10 ₂ , scan electrodes SC _{1 to} SC are supplied from sustain pulse generating circuit 516. It is possible to obtain the same effect that the impedance up to _n is varied to limit the discharge current in the sustain discharge in the discharge cell to reduce the light emission luminance.

FIG. 7 is a circuit diagram showing still another example of the PDP drive circuit according to Embodiment 1 of the present invention. Similar to the PDP drive circuit shown in FIG. 6, the PDP drive circuit shown in FIG. 7 includes a scan electrode drive circuit 506. The scan electrode drive circuit 506 includes a sustain pulse generation circuit 516, an initialization waveform generation circuit 52, and a scan pulse. and a switching circuit comprising a generator circuit 53 and the switching element _{S9 1, S9 2, S10 1} , S10 2. Further, in the PDP driving circuit shown in FIG. 7, the sustain electrodes _SU 1 to SU _n and between the ground potential, the switching element _S11 1 connected in parallel, S11 ₂ and switching element _S12 1 connected in parallel, S12 ₂ is inserted in series, and a switch circuit configured such that the body diodes are connected in back-to-back connection is inserted.

For example, in the configuration shown in FIG. 7, the impedance between the ground potential and the sustain electrodes _SU 1 to SU _n by selectively turning on the switching element _{S11 1, S11 2,} S12 1 and S12 ₂ Since it can be varied, it is possible to further increase the variable width of the impedance when driving sustain electrodes SC _{1 to} SC _n by sustain pulse generation circuit 516. The circuit configuration for connecting the PDP 10 and the ground potential is not limited to the one in which the switching elements S11 ₁ , S11 ₂ , S12 ₁ and S12 ₂ are connected to each other as shown in FIG. The present invention is not limited to the circuit configuration.

6 and 7 show an example in which the configuration for varying the impedance shown in the first embodiment is applied to another circuit example. However, the configuration shown in the second and third embodiments is shown. It is also possible to apply a configuration for changing the impedance in the same manner. The scanning electrodes _SC 1 to SC _n that may be used as the configuration for applying a sustain pulse to the sustain electrodes _SU 1 to SU _n are connected to the ground potential of course.

Further, the sustain pulse generation circuit 516 in FIGS. 6 and 7 does not describe the power recovery circuit formed by the coil L1, the diodes D1 and D2, the switching elements S1 and S2, and the recovery capacitor C1 shown in FIG. However, the same power recovery circuit may be provided in the sustain pulse generation circuit 516 shown in FIGS. FIG. 8 is a circuit diagram showing still another example of the PDP drive circuit according to Embodiment 1 of the present invention. The PDP drive circuit shown in FIG. 8 includes a scan electrode drive circuit 508. The scan electrode drive circuit 508 includes a sustain pulse generation circuit 518, an initialization waveform generation circuit 52, a scan pulse generation circuit 53, and switching elements S9 ₁ and S9 _2. , S10 ₁ and S10 ₂ . At this time, for example, as shown in FIG. 8, in the sustain pulse generation circuit 518, a power recovery circuit is formed by the coil L1, the diodes D1, D2 and the switching elements S1, S2 excluding the recovery capacitor C1, and the drain terminal of the switching element S1 and The source terminal of the switching element S2 may be directly connected to the ground potential.

  In the embodiment of the present invention, it is possible to adopt a configuration in which some or all of the configurations shown in the first to third embodiments are combined, thereby further increasing the variable width of the impedance. It is also possible to enlarge it.

  Further, in the first to third embodiments of the present invention, a generally known insulated gate type having a feature that a part or all of the switching elements are low loss and easy to control even during high voltage operation. A bipolar transistor (IGBT) may be used. In addition, since a parasitic diode is not generated in the IGBT due to its structure, it is desirable to provide a diode corresponding to a body diode generated parasitically in the MOSFET.

  In the first to third embodiments of the present invention, the impedance in the discharge path may be switched between the sustain period of one subfield and the sustain period of another subfield. There is no need to keep the impedance constant throughout the sustain period. For example, the impedance is switched between the first half and the second half of one sustain period, or the impedance is increased by a predetermined number of sustain pulses in one sustain period. It is possible to freely set a combination of impedance switching in the sustain period, such as a configuration in which all the remaining impedances are lowered.

  According to the PDP driving circuit and the plasma display device according to the present invention, the discharge current at the time of the sustain discharge is controlled by controlling the impedance in the discharge path, thereby reducing the luminance without impairing the gradation. Since display can be performed, it is useful as a PDP driving circuit and a plasma display device.

1 is a circuit diagram of a PDP drive circuit according to Embodiment 1 of the present invention. Circuit diagram of the PDP drive circuit in Embodiment 2 of the present invention Circuit diagram of the PDP drive circuit in Embodiment 3 of the present invention The circuit diagram of the other example of the PDP drive circuit in Embodiment 3 of this invention Circuit diagram of scan pulse generation circuit in an embodiment of the present invention The circuit diagram which showed another example of the PDP drive circuit in Embodiment 1 of this invention FIG. 5 is a circuit diagram showing still another example of the PDP drive circuit according to Embodiment 1 of the present invention. FIG. 5 is a circuit diagram showing still another example of the PDP drive circuit according to Embodiment 1 of the present invention. Perspective view showing structure of PDP Electrode arrangement of the PDP The figure which shows each drive voltage waveform applied to each electrode of the PDP The block diagram which shows the electrical constitution of the plasma display apparatus incorporating the same PDP Circuit diagram of scan electrode drive circuit with power recovery circuit and sustain pulse generation circuit with sustain electrode drive circuit

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AD converter 2 Video signal processing circuit 3 Subfield processing circuit 4 Data electrode drive circuit 5,501,502,503,504,506,508 Scan electrode drive circuit 6 Sustain electrode drive circuit 10 Plasma display panel (PDP)
20 (made of glass) front plate 22 scan electrode 23 sustain electrode 24, 33 dielectric layer 25 protective layer 30 (made of glass) back plate 32 data electrode 34 partition 35 phosphor layer 51, 61, 62, 511, 512 513, 514, 516, 518 Sustain pulse generation circuit 52 Initialization waveform generation circuit 53 Scan pulse generation circuit C1, C2 Recovery capacitor C31 Capacitor L1, L2, L1A, L1B Coil D1, D2, D3, D31, D4, D10 Diode S1 , S2, S3, S4, S5, S5 ₁ , S5 ₂ , S6, S6 ₁ , S6 ₂ , S7, S7 ₁ , S7 ₂ , S8, S8 ₁ , S8 ₂ , S9, S9 ₁ , S9 ₂ , S10, S10 _{1, S10 2, S11 1,} S11 2, S12 1, S12 2, S21, S22, S31, S32, S41, S 42 Switching element V1, V2, V3, V4, V5 Constant voltage power supply IC31 ScanIC

Claims (9)

A plasma display panel driving circuit for driving a plasma display panel having a plurality of scan electrodes and sustain electrodes constituting a display electrode pair to generate a sustain discharge in the display electrode pair,
A plasma display panel driving circuit, wherein an impedance from a circuit provided for generating the sustain discharge to the scan electrode or the sustain electrode is variable. A plasma display for driving the plasma display panel by applying voltages having different drive waveforms to the scan electrode and the sustain electrode of the plasma display panel in each period of a subfield having an initialization period, an address period, and a sustain period A panel drive circuit,
A scan electrode driving circuit connected to the scan electrode;
A sustain electrode drive circuit connected to the sustain electrode,
Each of the scan electrode drive circuit and the sustain electrode drive circuit includes a sustain pulse generation circuit that generates a sustain pulse to be applied to the scan electrode or the sustain electrode in each sustain period of a plurality of subfields constituting one field. ,
2. The plasma display panel driving circuit according to claim 1, wherein an impedance from the sustain pulse generating circuit to the scan electrode or the sustain electrode is variable. The scan electrode driving circuit includes:
An initialization waveform generation circuit that is provided between the sustain pulse generation circuit and the scan electrode and generates an initialization waveform applied to the scan electrode in the initialization period;
A switch circuit provided between the sustain pulse generation circuit and the initialization waveform generation circuit for electrically separating the initialization waveform generation circuit and the sustain pulse generation circuit;
3. The plasma display panel drive circuit according to claim 2, wherein the impedance from the sustain pulse generating circuit to the scan electrode is made variable by making the impedance in the switch circuit variable. The switch circuit includes a first switch configured by a plurality of switching elements connected in parallel and capable of interrupting a current flowing from the sustain pulse generation circuit to the initialization waveform generation circuit, and the initialization waveform generation circuit And a second switch configured by a plurality of switching elements connected in parallel capable of interrupting a current flowing from the sustain pulse generation circuit to the sustain pulse generation circuit,
4. The impedance in the switch circuit is made variable by selectively conducting a plurality of switching elements constituting the first switch and the second switch. Plasma display panel drive circuit. The sustain pulse generating circuit includes: a power recovery unit that recovers power accumulated in a capacitive load of the electrode of the plasma display panel in a recovery capacitor by LC resonance and reuses the recovered power for driving the plasma display panel; A power clamp switch configured to clamp the electrodes of the plasma display panel to a power supply potential and a plurality of switching elements connected in parallel; and a ground potential to the electrodes of the plasma display panel A clamp portion having a ground clamp switch for clamping to
By selectively conducting the plurality of switching elements constituting the power clamp switch and the ground clamp switch, impedances in the power clamp switch and the ground clamp switch are varied, thereby causing the sustain pulse generating circuit to 3. The plasma display panel driving circuit according to claim 2, wherein the impedance to the scanning electrode or the sustaining electrode is variable. The sustain pulse generating circuit included in the scan electrode driving circuit is:
A power recovery coil that recovers the power accumulated in the capacitive load of the scan electrode by LC resonance with the capacitive load of the scan electrode as a recovered power and the LC load with the capacitive load of the scan electrode and the LC load A power recovery unit having a power supply coil for supplying the recovered power accumulated in the recovery capacitor as supply power to the capacitive load of the scan electrode;
A clamp unit having one end connected to a power supply potential, a power supply clamp switch for clamping the scan electrode to the power supply potential, and a ground clamp switch for clamping the scan electrode to the ground potential;
A switch composed of a plurality of switching elements connected in parallel to the other end of the power clamp switch, connected in series with the power clamp switch and capable of interrupting a current flowing to the power supply potential via the power clamp switch With circuit,
The impedance in the switch circuit is made variable by selectively conducting a plurality of switching elements constituting the switch circuit, thereby making the impedance from the sustain pulse generating circuit to the scan electrode variable. The plasma display panel drive circuit according to claim 2, wherein: 7. The plasma according to claim 6, wherein the switch circuit is configured by connecting in parallel at least one switching element and at least one diode arranged in a direction to cut off a current flowing to the power clamp switch. Display panel drive circuit. The scan electrode drive circuit has a scan pulse generation circuit that generates a scan pulse to be applied to the scan electrode during the address period,
The scan pulse generation circuit switches a constant voltage power source having a different voltage value to generate the scan pulse in the address period and applies it to the scan electrode, and changes the passage path of the sustain pulse in the sustain period. A plurality of switching elements that can be switched, and selectively switching the plurality of switching elements in the sustain period to change a passage path of the sustain pulse, thereby causing the sustain pulse generation circuit to the scan electrode. 3. The plasma display panel drive circuit according to claim 2, wherein the impedance of the plasma display panel is variable. A plurality of scan electrodes and sustain electrodes arranged in parallel on the first substrate and constituting a display electrode pair, and the scan electrodes on a second substrate arranged opposite to the first substrate across a discharge space A plasma display panel having a plurality of data electrodes arranged in a direction intersecting with each other and forming a discharge cell with the display electrode pair;
A plasma display device comprising the plasma display panel drive circuit according to claim 1.

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