JP2008134372A - Driving circuit of plasma display panel and plasma display panel module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving circuit of plasma display panel (PDP) which can reduce power loss of a reset diode and permits surface mount of the reset diode. <P>SOLUTION: A resistance is connected to the reset diode which resets residual energy of a recovery coil, the residual energy is consumed by the resistance and the reset diode is made low-loss, whereby a PDP module which improves reliability, reduces cost and is suited for forming a hybrid IC with peripheral semiconductors can be provided. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a driving circuit and a PDP module for a plasma display panel (hereinafter abbreviated as “PDP”) that performs display using alternating current discharge, and in particular, the residual energy of a recovery coil used in a power recovery circuit. Related to reset technology.

  In recent years, PDPs have been put to practical use as display panels that replace CRTs because they are self-luminous, have good visibility, are thin, can display large screens, and display at high speed.

  The main power consumption in this PDP is to drive the discharge power that contributes to the display and the capacitance (hereinafter referred to as “panel capacitance”) formed between the scan electrode (Y electrode) and the sustain electrode (X electrode). Reactive power to be.

Reactive power does not contribute to the display. Therefore, in order to reduce reactive power, the PDP drive circuit includes a power recovery circuit that forms a resonance circuit with a panel capacitance and an inductance provided outside, and recovers and re-supplys the power stored in the panel capacitance. Is provided. The power recovery circuit is described in Patent Documents 1 and 2, for example.
JP 2002-278512 A JP 11-352927 A

  The general power recovery circuit described above is shown in FIG. Hereinafter, with reference to FIG. 1 of Patent Document 1, a problem of a power recovery circuit of a conventional PDP will be described.

  The operation sequence in which a driving voltage is applied to the PDP to cause a sustain discharge (also referred to as a sustain discharge) starts with a power supply operation for supplying power from the power recovery circuit side to the panel capacity of the PDP. Here, it is assumed that the PDP is sustain-driven from the X electrode side. That is, the panel capacitor Cp starts to be charged through the switch SW2, the diode D032, the coil 65, and the diode D034 from the recovery capacitor C3 in which the power recovered from the panel capacitance Cp is stored. Since the discharge starts when the charge voltage to the PDP exceeds the discharge start voltage, the switch SW4 is closed even during the charging of the panel capacitance Cp, and the sustain voltage (also referred to as the discharge sustain voltage) Vs is applied to the PDP to increase the discharge at once. .

  Next, after a certain period of time (about several μs) after the discharge is finished, the operation shifts to an operation for recovering the electric power stored in the panel capacitor Cp (an electric power recovery operation). That is, the electric power charged in the panel capacitance Cp is recovered by the recovery capacitor C3 through the diode D033, the coil 64, and the diodes D031, SW1. Thereafter, the switch SW3 is closed, the residual voltage of the PDP (panel capacitance Cp) is lowered to the reference potential, and the driving ends.

  Next, sustain drive is performed in the same manner from the opposite electrode (here, Y electrode) side. Thereafter, the X electrodes 14 and the Y electrodes 15 coming out from both sides of the panel capacitance Cp are alternately driven to continue (maintain) the sustain discharge.

  By the way, if the switch SW4 is closed while the power is being supplied from the coil 65 to the PDP (panel capacitance Cp) in the process of the power supply operation described above, charging of the diode D032 and the coil 65 that are turned on (conduction) is prevented. The sustain voltage Vs is applied in the direction. Accordingly, the current of the coil 65 rapidly becomes zero, and the current further flows in the negative direction (in the direction of the recovery capacitor C3) for the reverse recovery time (trr) of the diode D032. The diode D032 is a large diode capable of flowing a recovery current of about several tens of amperes, and the trr time is considerably longer than that of a small product. When the switch SW4 is turned on, a current of about 6.5 A flows in the negative direction when measured (when trr = 0.1 μs in a 42-inch PDP). That is, after the power supply operation is finished, residual energy charged in the negative direction remains in the coil 65, and unless this energy is discharged, the surrounding stray capacitance is charged and harmonic ringing occurs, and EMI (Electromagnetic Interference) ) Interfering. For this reason, a diode D037 is added, and the residual energy of the coil 65 is discharged by a closed circuit formed by the coil 65, the diode D037, and the switch SW4. Note that discharging the residual energy of the coil 65 to the initial state is referred to as “reset” for the sake of convenience in order to avoid mixing with the sustain discharge. A diode for discharging residual energy (here, D037) is particularly referred to as a “reset diode”.

The residual energy (electric power) accumulated in the coil 65 is obtained by 1 / 2Li ² × (number of pulses per second). Considering the case where a white peak image is received by the current product (for example, a plasma display display device equipped with a 42-inch PDP) and the number of discharge pulses is maximum (for example, 700 shots / 16.7 ms), L = 0.3 μH , If the number of pulses per second is 42,000, and the power is calculated based on the measured current waveform, it is necessary to reset by consuming about 0.3 W (watts) of power. This consumption is mostly performed by the reset diode D037, resulting in a heat loss determined by the product of the forward voltage (Vf) and the flowing current.

  For this reason, conventionally, a surface mount type diode (for example, SMA type diode) cannot be used as the reset diode D037. Generally, a large self-standing diode (for example, a diode enclosed in a TO-220 type semiconductor package). Is used. If necessary, heat sink mounting must also be considered. These circumstances increase the cost (part price, board mounting cost, etc.).

  In addition, the reset diode is required to be made as small and low-loss component as possible in order to promote IC integration with other peripheral semiconductor components.

  On the other hand, in the power recovery operation from the PDP (panel capacity Cp), there is no problem of necessity that the power supply is interrupted during supply. However, the actual situation is to shorten the power recovery time as much as possible, increase the number of sustain pulses by that amount, and increase the brightness, and the interruption is still performed during the power recovery.

  As described above, during the power recovery operation, power is recovered from the panel capacitance Cp to the recovery capacitor C3 through the diode D033, the coil 64, the diode D031, and the switch SW1. At this time, even near the end of power recovery, there is a loss such as electrode resistance, so that all the power stored in the panel capacitance Cp of the PDP cannot be recovered, and a voltage component remains in the panel capacitance Cp. For this reason, as described above, even when the switch SW3 is closed and the power recovery is interrupted in the middle of the power recovery due to the shortening of time, residual energy is generated in the coil 6 for the same reason as described above.

  In other words, current flows from the recovery capacitor C3 to the coil 64 through the trr of the diode D031 in the reverse direction (direction on the PDP side), and residual energy is generated in the coil 6.

  Therefore, a reset diode D036 is added, and the residual energy of the coil 64 is reset by a closed circuit formed by the reset diode D036, the coil 64, and the switch SW3. Accordingly, the reset diode D036 also has a power loss of about 0.3 W (watts), which is almost the same as described above, so that large parts are used and it is difficult to reduce the size.

  On the other hand, FIG. 4 of Patent Document 2 shows that a resistor is connected to a reset diode for resetting the residual energy of the recovery coil, and current damping (braking) is performed by the resistor. The technique shown in FIG. 4 is described as a technique for increasing luminous efficiency by increasing the coil energy of the power recovery circuit to generate an overshoot waveform at the leading edge of the sustain pulse waveform.

  However, although the details will be described later, the resistor is for the purpose of current damping (braking), has a resistance value as small as about 1Ω, and is intended to reduce ringing components superimposed on the current waveform, etc. It is not possible to reduce the power consumption.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a driving circuit for a plasma display panel that can reduce the power loss of the reset diode and enable the surface mounting of the reset diode.

  A voltage source that is approximately half of the discharge sustaining voltage of the plasma display panel is connected to the panel electrode through a bidirectional switch circuit composed of a semiconductor switch and a high-speed diode (trr = 0.1 μs or less) and a recovery coil. A semiconductor switch is connected between the discharge sustaining power supply and between the reference potential, and a diode and a resistor (3 to 50Ω) having a discharge sustaining voltage side as a cathode between the connection point of the bidirectional switch circuit and the coil to the discharge sustaining power supply. A series circuit of a diode and a resistor (3 to 50Ω) having a reference potential as the anode side is connected between the connection point and the reference potential, and the residual energy of the recovery coil is almost equal to this resistance. The power loss of the diode having the discharge sustaining voltage side as the cathode and the diode having the reference potential side as the anode is reduced. And wherein the door.

  According to the present invention, by connecting a resistor of 3 to 50Ω in series with the reset diode, it is possible to share the power loss with the resistor and to reduce the power loss in the reset diode accordingly. As a result, a reset diode with low power consumption that can be surface-mounted can be used, and the cost can be reduced.

  Hereinafter, the best mode of the present invention will be described in detail with reference to the drawings. In each figure, elements having a common function are indicated by the same reference numerals, and those that have been described once will not be described repeatedly.

  The present invention is characterized in that a resistor is connected to a reset diode that resets the residual energy of the recovery coil. When the residual energy of the recovery coil is reset, if there is no resistance, the residual energy is converted into heat loss mainly by the reset diode. For this reason, currently, for example, a reset diode encapsulated in a TO-220 type semiconductor package is used in consideration of heat dissipation. Therefore, a resistor is connected to the reset diode, and the heat loss is shared by the resistor to reduce the heat loss imposed by the reset diode. Thereby, a surface mount type reset diode can be used, and cost reduction can be achieved. In addition, a hybrid IC with a peripheral semiconductor can be realized.

  Note that if the resistance value is too small, the heat sharing by the resistance is reduced, and if the resistance is too large, ringing is likely to occur. Therefore, the resistance value of the resistance is set to 3Ω to 50Ω.

  FIG. 1 is a schematic diagram of a sustain discharge driving circuit of a plasma display panel according to Embodiment 1 of the present invention. FIG. 2 is a diagram schematically showing the voltage waveform and current waveform of each part in the drive circuit of FIG.

  The present invention relates to a Y electrode drive circuit and an X electrode in a sustain period (discharge sustain period) in which a PDP (plasma display panel) is alternately driven to sustain discharge from the Y electrode (scan electrode) side and the X electrode (sustain electrode) side. The present invention relates to a power recovery circuit of a drive circuit. Therefore, hereinafter, the power supply and the power recovery operation of the power recovery circuit according to the present invention in the sustain period will be mainly described, and the description of the driving of the PDP in the reset period and the address period will be omitted.

  In FIG. 1, a PDP 14 is a known PDP having a three-electrode surface discharge structure. In a PDP having a three-electrode surface discharge structure, a plurality of pairs of Y electrodes and X electrodes extending in the screen row direction are generally arranged in the screen vertical direction. Although not shown, a plurality of address electrodes extending in the screen vertical direction are arranged in the screen row direction. A display cell (not shown) is formed at each intersection of each display line and each address electrode formed by a pair of Y electrode and X electrode.

  As is well known, the driving of the PDP 14 first initializes (resets) all display cells during the reset period. Next, a display cell to be lit in the address period is selected. Specifically, while applying a scan pulse (scan pulse) from the scan circuit 13 to each Y electrode, a process of applying a display pulse synchronized with this from the address drive circuit (not shown) to the address electrode is performed. Wall charges are formed on the display cells to be generated. Thereafter, a sustain pulse (discharge sustaining pulse) is alternately applied to the PDP 14 from the Y electrode driving circuit 100Y and the X electrode driving circuit to light up the display cell in which the wall charges are formed.

  The Y electrode drive circuit 100Y that drives the PDP 14 from the Y electrode side collects power from the sustain circuit 110Y that sustains the Y electrode and the panel capacitance Cp (not shown) of the PDP 14, and supplies power to the panel capacitance Cp. Power recovery circuit 120Y. The X electrode drive circuit 100X that drives the PDP 14 from the X electrode side is configured in the same manner as the Y electrode drive circuit 100Y, and includes a sustain circuit 110X that sustains the X electrode and a power recovery circuit 120X. Hereinafter, the detailed configurations of the Y electrode drive circuit 100Y and the X electrode drive circuit 100X will be described. However, the Y electrode drive circuit 100Y and the X electrode drive circuit 100X have the same configuration, and are representatively represented by the Y electrode drive circuit 100Y. The detailed configuration will be described. In the Y electrode driving circuit 100Y and the X electrode driving circuit 100X, corresponding elements having the same function are denoted by the same reference numerals, and when it is necessary to distinguish, subscripts y, Let x be attached.

  The sustain circuit 110Y includes switches 1 and 2 configured by semiconductor switches (for example, MOSFETs). The switches 1 and 2 are connected in series, one of which is connected to a power supply (hereinafter referred to as “sustain power supply”) that supplies a sustain voltage (discharge sustaining voltage) Vs to the PDP, and the other is connected to a reference potential (here, It is connected to the ground potential hereinafter referred to as “GND”. Further, a midpoint (symbol a in FIG. 1) that is a connection point between the switch 1 and the switch 2 is connected to the Y electrode via the scan circuit 13. Note that the middle point of the sustain circuit 110X on the X electrode side is indicated by symbol b.

  The power recovery circuit 120Y includes a recovery capacitor 3 that recovers power from the panel capacitance Cp of the PDP and supplies the recovered power, a semiconductor switch, and a high-speed diode, and a bidirectional switch that switches the polarity of the flowing current bidirectionally. The circuit 130Y, the recovery coil 6 for causing series resonance with the panel capacitance Cp of the PDP, the diodes 9 and 11 for resetting the residual energy accumulated in the recovery coil 6, and the resistors connected in series to the reset diodes 9 and 11, respectively. 10 and 12.

  One of the recovery capacitors 3 is connected to GND, and the other is connected to the bidirectional switch 130Y. One of the bidirectional switches 130Y is connected to the recovery capacitor 3, and the other is connected to the recovery coil 6. The other end of the recovery coil 6 is connected to the midpoint a of the sustain circuit 110Y. At the connection point between the bidirectional switch 130Y and the recovery coil 6, a diode 9 and a resistor 10 connected in series are connected between the sustain power source and a diode 11 and a resistor 12 connected in series are connected between the GND and the GND. It is connected.

  Here, the bidirectional switch circuit 130Y is configured by connecting a switch 4 formed of a semiconductor switch and a diode 5 connected in series thereto, and a switch 7 and a diode 8 connected in series in parallel. . However, the present invention is not limited to this, and for example, a bidirectional switch circuit having the configuration shown in FIGS. 3 and 4 may be used.

  Next, the sustain drive operation by the Y electrode drive circuit 100Y will be described with reference to the voltage and current waveforms in FIG. Since the scan circuit 13 operates in the through period during the sustain period, it will be ignored below.

  The basic period of the sustain period (for example, the period for driving the PDP from the Y electrode side or the period for driving the PDP from the X electrode side) is a power supply period T1 (T5) for charging the panel capacitor Cp as shown in FIG. And a unit sustain period T2 (T6) in which the sustain voltage Vs is applied to the PDP for a predetermined period, and a power recovery period T3 (T7) in which the energy (power) accumulated from the panel capacitance Cp is recovered. There is a drive circuit switching period T4 between the end of the previous basic period and the start of the next basic period.

  The driving operation for the sustain discharge is basically the same as that in Patent Document 1, and only the outline is described, and the operation at the time of resetting the residual energy of the recovery coil related to the present invention will be described in detail.

  The operation in the power supply period T1 will be described. In the power supply period T1, first, the switch 2x of the X electrode drive circuit 100X is closed to set the X electrodes (X1 to Xn) to the reference potential (GND) level.

  Thereafter, the Y electrode side (that is, the panel capacitance Cp) of the PDP 14 starts to be charged from the recovery capacitor 3 of the Y electrode drive circuit 100Y through the switch 4, the diode 5, and the recovery coil 6. When the voltage rises and exceeds the discharge start voltage determined by the electrode structure of the PDP, the discharge starts. At this time, the next unit sustain period T2 is entered, the switch 1 is closed, the voltage is increased to the Vs voltage, and the discharge is increased at once.

  In the unit sustain period T2, a constant voltage Vs is applied to the Y electrode for a predetermined time. In the next power recovery period T3 following the unit sustain period T2, the switch 1 is opened, and then power is recovered from the Y electrodes (Y1 to Yn) to the recovery capacitor 3 through the coil 6, the diode 8, and the switch 7. The switch 2 closes near the end of recovery and ends. Next, in the drive circuit switching period T4, the drive circuit is switched from the Y electrode drive circuit to the X electrode drive circuit in order to drive the PDP from the X electrode drive circuit 100X. Next, the same operation as described above is repeated in the X electrode driving circuit, and the sustain discharge is maintained.

  By the way, when the switch 1 is closed and the sustain voltage Vs is applied at the beginning of the unit sustain period T2, the reverse current from the sustain power source (+ Vs) to the recovery coil 6 is prevented so as to block the current flowing to the PDP side flowing in the recovery coil 6. Directional current inflow also begins. This current flows so as to charge the diode 5, the switch 4, and the recovery capacitor 3. The flow continues until determined by the reverse recovery time (trr) of the diode 5.

  In the case of the conventional power recovery circuit, as shown by the trr current waveform in FIG. 2 (5), even when a commercially available high-speed diode (trr = 0.1 μs) is used in a 42-inch PDP, it is about 6. It was observed that about 5A was flowing.

Due to the reverse current, 1/2 Li ² of energy is stored in the recovery coil 6. The residual energy accumulated in the recovery coil 6 is then reset by a closed circuit formed by the recovery coil 6, the reset diode 9, the sustain power supply (+ Vs), and the switch 1. The reset start current value is a value determined by trr (reverse recovery time) of the diode 5.

  As described in the problem section, when a 42-inch PDP uses a high-speed diode with trr = 0.1 μs for the diode 5 and a coil with L = 0.3 μH for the recovery coil 6, the reverse current is the peak current. Is about 6.5 A, and the residual energy of the recovery coil 6 is about 0.3 W. For this reason, conventionally, a diode of TO-220 type semiconductor package is used for the diode 9 for resetting the power for heat dissipation.

  Therefore, in order to share the electric power provided by the reset diode 9 described above, in this embodiment, the resistor 10 is inserted into the above-described closed circuit that resets the residual energy of the recovery coil 6. Specifically, a resistor 10 is added between the reset diode 9 and the sustain power source (+ Vs). If the resistor 10 is added, power can be consumed by the resistor 10 and power consumed by the reset diode 9 can be reduced.

  In this embodiment, a surface mount diode (for example, SMA type) is used as the reset diode 9 in order to reduce the cost. The SMA type has a rated power consumption of about 0.2 W, and in consideration of load reduction due to a temperature rise, the reset diode 9 is charged with 0.1 W. For this reason, 0.2 W is assigned to the resistor 10. When the resistance 10 was experimentally obtained under these conditions, it was about 3Ω.

  FIG. 2 (3) shows an actual measurement waveform when 4.7Ω which is slightly larger than 3Ω is used as the resistance value of the resistor 10. FIG.

  (3) and (5) in FIG. 2 show the comparison of the consumption period of the residual energy in the case of this example and in the case of no resistance. In this example, in the case of this example, the resistance per unit time is shown. Since the power consumption is large, the consumption period is shortened. Thereby, the power consumption of the reset diode 9 is reduced, and the reset current converges in a short time, so that the reliability is improved.

  As a result of experimenting with the resistance value of the resistor 10 being varied, the period of power consumption is shortened and the power loss is effectively lost up to about 50Ω, but if it is increased more than this, the period of power consumption remains unchanged. It is observed that ringing increases as the amount of charge in the surrounding stray capacitance increases, and the upper limit resistance value is limited.

  The residual energy of the recovery coil 6 is reset not only when the power supply period T1 shifts to the unit sustain period T2, but also when the power recovery period T3 shifts to the drive circuit switching period T4.

  Specifically. The power recovery period T3 ends by closing the switch 2 near the end of power recovery. However, at this time, there is a loss due to the electrode resistance or the like of the PDP, and 100% cannot be recovered, and a voltage remains in the PDP (panel capacitance Cp). Further, in a state where the recovery time is shortened and the number of sustain pulses is generally increased correspondingly, the switch 2 is turned on while the voltage remains in the PDP.

  At this time, the reverse current recovery characteristic of the diode 8 causes the current to reverse from the current through the path from the recovery capacitor 3 to the switch 7, the diode 8, the recovery coil 6, and the switch 2 so that the recovery current of the coil 6 is blocked. It flows in the direction (see (5) in FIG. 2). As a result, residual energy is generated in the coil 6, but energy reset is performed in the closed circuit of the recovery coil 6, the switch 2, GND, the resistor 12, and the reset diode 11 as described above.

  Also here, in order to make the loss of the reset diode 11 about 0.1 W or less, like the resistor 10, the resistor 12 is assigned a loss of about 0.2 W. The measured current waveform when the resistance values of the resistors 10 and 12 are 4.7Ω is (3) in FIG.

  As described above, according to the present embodiment, surface mounting can be achieved by setting the reset diode for resetting the residual energy accumulated in the recovery coil to about 0.1 W or less that can be surface mounted. It is possible to reduce the component unit price and the man-hour (that is, cost) for mounting the component on the board. Further, the time during which the reset current flows can be shortened, and the reliability is improved. In addition, since power consumption is reduced, a hybrid IC with a peripheral semiconductor can be realized.

  Further, if the loss sharing resistors 10 and 12 are arranged on the sustain power supply (+ Vs) side and the GND side, a diode chip in which reset diodes 9 and 11 are integrated into an IC as surrounded by a dotted frame 25 in FIG. By using, it is possible to reduce the number of parts mounting man-hours (that is, cost).

  Note that FIG. 4 of Patent Document 2 discloses that a resistor is connected in series to a reset diode for resetting the residual energy accumulated in the recovery coil.

  This disclosure is described in the invention in which the coil energy of the power recovery circuit is increased to generate an overshoot waveform exceeding the sustain voltage Vs at the leading edge of the sustain (discharge sustaining) pulse waveform to increase the light emission efficiency. .

  Hereinafter, in order to explain the difference between this known example and the embodiment according to the present invention, an outline of the operation will be described with reference to FIG. 4 of the known example.

  Prior to supplying power from the recovery capacitor CP31 to the PDP (CP1), the known operation is to close the SW 34 in advance and connect the recovery capacitor L31 to the PDP (CP1) via the SW31 and the diode DD31. Energy is stored such that the supply voltage is equal to or higher than the sustain voltage Vs of TP2 (sustain power supply terminal). Thereafter, the SW 34 is turned off, and this energy is given to the PDP (CP1) to increase it to the TP2 voltage Vs or higher.

  When the applied current from the SW31, the diode DD31, and the recovery coil L31 to the PDP becomes zero, the voltage of the PDP (CP1) reaches the maximum peak, and thereafter, the diode DD31 that is turned off starts to be discharged in the reverse direction. .

  Here, if the diode DD31 is a high speed type and the reverse recovery time (trr) is short (for example, around trr = 0.1 μs), the PDP (CP1) can hardly be discharged, and the PDP (CP1) is the maximum. Keeps the voltage. However, since it is necessary to lower the intent of the invention of the known example, a soft recovery type diode (trr = 0.3 μs) having the characteristics shown in FIG. It is described that the current can flow in the direction. That is, a current is passed from the PDP (CP1) to the recovery capacitor CP31 side for a time defined by the reverse recovery time (trr) of the soft recovery type (trr), and the terminal TP1 of FIG. As shown in the voltage waveform, the voltage of PDP (CP1) is lowered.

When the current defined by the reverse recovery time (trr) has finished flowing, the diode DD31 is turned off. At this time, the recovery coil L31 has an energy of 1/2 Li ^{2 due to} the peak current (i) that has flowed during the soft recovery time. (Residual energy) is saved. This residual energy is longer than when a high-speed diode with a short reverse recovery time is used because the soft recovery time is long.

  Therefore, in order to reset this large coil energy, a closed circuit of the recovery coil L31, the diode DD35, the resistors R31, SW33, and the diode DD33 is configured. A resistor R31 is inserted in the closed circuit for resetting the coil energy as in the present invention.

  However, unlike the present invention, this resistor R31 is described as a resistor for current damping in Patent Document 2. And 3.3Ω / 3W is used in parallel (total value 1.1Ω / 9 watts).

  The reason for adopting this resistance value is not clearly described in Patent Document 2, but is presumed to be due to the following reason. That is, if the resistance value of the resistor R31 is large, the effect of current damping is enhanced, but since the residual energy is large, the generated voltage increases correspondingly, for example, it is considered that the EMI cannot be increased and the resistance value cannot be increased. .

  In the method described in the known example of Patent Document 2, a soft recovery type is indispensable for the diode DD31 that determines the coil energy, which increases the residual coil energy. For this reason, it is necessary to release (reset) a large amount of stored energy without causing ringing while performing current damping (braking) by resistance insertion. Therefore, the resistance value of the resistor R31 is set to about 1Ω. That is, the role of the resistor R31 in Patent Document 2 is current damping (preventing ringing caused by the inductive component), and is not intended to reduce the power consumption of the diode DD35. Here, there is a big difference between the present invention and Patent Document 2.

  Further, in Patent Document 2, no particular consideration is given to resetting the residual energy of the recovery coil that occurs when recovering power from the PDP. This is considered to be not considered because the diode DD32 uses a normal high-speed diode with a short reverse recovery time and has a relatively small residual energy as compared with the case of the soft recovery diode. Also from this point, it can be read that the power consumption reduction of the reset diode of the present invention is not aimed.

  As described above, according to the present invention, by connecting a resistor of 3 to 50Ω in series with the reset diode (a larger resistance value is more effective for power sharing), the resistance is accumulated in the recovery coil. The power loss due to the residual energy is shared, and the power loss in the reset diode can be reduced accordingly. As a result, a reset diode that can be surface-mounted can be used, and the cost can be reduced.

  In the above-described embodiment, the bidirectional switch circuit 130Y is configured by connecting in parallel the switch 4 and the diode 5 connected in series and the switch 7 and the diode 8 connected in series. It is not limited to this. 3 and 4 are modifications thereof. The configuration of this modification is well known, and corresponding elements in FIGS. 3 and 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the power recovery circuit 120 of the first embodiment described above, power is supplied from the recovery capacitor 3 to the PDP 14 (panel capacity Cp) in the power supply period T1 and the PDP 14 (panel capacity Cp in the power recovery period T3) with one recovery coil 6. ) To the recovery capacitor 3. The present invention is applied to the power recovery circuit 120. However, the present invention is not limited to this case. For example, the present invention can also be applied to the case where two coils, that is, a series resonance coil for power supply in the power supply period T1 and a series resonance coil for power recovery in the power recovery period T3 are used.

  Hereinafter, Embodiment 2 according to the present invention will be described with reference to FIG. FIG. 5 is a schematic diagram of a sustain driving circuit of the plasma display panel according to the second embodiment of the present invention. Since the Y electrode driving circuit and the X electrode driving circuit for driving the PDP 14 have the same configuration, the suffixes x and y are omitted in FIG. Also, elements having the same functions as those in FIG. 1 are denoted by the same reference numerals, and redundant description thereof is omitted.

  As is clear from FIG. 5, the power recovery circuit 120A of the electrode drive circuit 100A according to the present embodiment is different from the first embodiment in that the power supply path from the recovery capacitor 3 to the PDP 14 and from the PDP 14 to the recovery capacitor 3 The power recovery path is different.

  Therefore, the bidirectional switch circuit 130A is separated on the coil side. Specifically, the switch 4 constituted by a semiconductor switch and the diode 5 connected in series thereto, and the switch 7 and the diode 8 similarly connected in series are separated on the coil side. A series resonance coil (hereinafter simply referred to as “coil”) 61 for supplying power is connected to the switch 4 and the diode 5 connected in series in the bidirectional switch circuit 130A, and the bidirectional switch circuit 130A is connected in series. A series resonance coil (hereinafter simply referred to as “coil”) 62 for power recovery is connected to the switch 7 and the diode 8.

  That is, the power supply path in the power supply period T1 is the recovery capacitor 3 → switch 4 → diode 5 → coil 61 → PDP14, and the power recovery path in the power recovery period T3 is PDP14 → coil 62 → diode 8 → switch 7 → The recovery capacitor 3 is obtained.

  In the above-described power recovery circuit 120A, when the power supply period T1 shifts to the unit sustain period T2, a current flows through the coil 61 in the opposite direction to that until now, and energy is accumulated. This stored residual energy must be reset (released). Therefore, the reset diode 9 is inserted between the connection point between the bidirectional switch 130A (the switch 4 and the diode 5 connected in series) and the coil 61 and the sustain power source (+ Vs). Thus, the residual energy is reset by a closed circuit formed by the coil 61, the reset diode 9, the sustain power source (+ Vs), and the switch 1. At this time, in order to share the electric power provided by the reset diode 9, in this embodiment as well, the resistor 10 is inserted into the above-described closed circuit that resets the residual energy of the coil 61 as in the first embodiment. . Specifically, a resistor 10 is added between the reset diode 9 and the sustain power source (+ Vs). If the resistor 10 is added, power can be consumed by the resistor 10 and power consumed by the reset diode 9 can be reduced.

  Also in this embodiment, a surface mount diode (for example, SMA type) is used as the reset diode 9 in order to reduce the cost. The SMA type has a rated power consumption of about 0.2 W, and in consideration of load reduction due to a temperature rise, the reset diode 9 is charged with 0.1 W. For this reason, 0.2 W is assigned to the resistor 10.

  A diode 31 is inserted between the connection point between the bidirectional switch 130A and the coil 61 and GND. This diode 31 is for reducing the influence of negative noise, and a large current does not flow, and a surface mount type diode (for example, SMA type) is used similarly to the reset diode 9. Of course, a resistor may be inserted.

  Further, not only when shifting from the power supply period T1 to the unit sustain period T2, but also when shifting from the power recovery period T3 to the drive circuit switching period T4, residual energy is accumulated in the coil. That is, a current flows through the coil 62 in the opposite direction to that of the current, and energy is accumulated.

  For example, when switching from the power recovery period T3 to the drive circuit switching period T4, if the recovery time is shortened and the switch 2 is turned on while the voltage remains in the PDP, the coil 62 is reversed. Current flows in the direction and energy is stored. This stored residual energy must be reset (released). Therefore, the reset diode 11 is inserted between the connection point between the bidirectional switch 130A (the switch 7 and the diode 8 connected in series) and the coil 62 and GND. Thereby, the residual energy is reset by a closed circuit formed by the coil 62, the switch 2, GND, and the reset diode 11. At this time, in order to share the electric power provided by the reset diode 11, the resistor 11 is inserted into the above-described closed circuit that resets the residual energy of the coil 62 in the present embodiment as well as the first embodiment. .

  Specifically, a resistor 12 is added between the reset diode 11 and GND. If the resistor 12 is added, power can be consumed by the resistor 12 and power consumed by the reset diode 11 can be reduced. Also here, in order to make the loss of the reset diode 11 about 0.1 W or less, like the resistor 10, the resistor 12 is assigned a loss of about 0.2 W.

  A diode 39 is inserted between the connection point between the bidirectional switch 130A and the coil 62 and the sustain power source (+ Vs). The diode 39 is for reducing the influence of positive noise, and a large current does not flow, and a surface mount type diode (for example, SMA type) is used in the same manner as the reset diode 11. Of course, a resistor may be inserted.

  As described above, also in this embodiment, surface mounting can be achieved by setting the reset diode for resetting the residual energy accumulated in the coils (61 and 62) to about 0.1 W or less that can be surface mounted. Therefore, it is possible to reduce the unit cost and the man-hour (that is, cost) for mounting the component on the board. Further, the time during which the reset current flows can be shortened, and the reliability is improved. In addition, since power consumption is reduced, a hybrid IC with a peripheral semiconductor can be realized.

  Further, if the resistors 10 and 12 for sharing the loss are arranged on the sustain power supply (+ Vs) side and the GND side, the reset diode 9, the diode 31, the diode 39, and the reset are surrounded by the dotted line frames 25 A 1 and 25 A 2 in FIG. If a diode chip in which the diode 11 is integrated into an IC is used, it is possible to reduce the number of parts mounting steps (that is, cost).

1 is a schematic diagram of a sustain drive circuit of a plasma display panel according to Embodiment 1 of the present invention. It is the figure which showed typically the voltage waveform and current waveform of each part in the drive circuit of FIG. 4 is another form of the bidirectional switch circuit shown in FIG. The diode polarity of the bidirectional switch circuit shown in FIG. 3 is reversed. It is a schematic diagram of the sustain drive circuit of the plasma display panel according to the second embodiment of the present invention.

Explanation of symbols

1 Switch 2 Switch 3 Recovery Capacitor 4 Switch 5 Diode 6 Recovery Coil 8 Diode 9 Reset Diode 10 Resistor 11 Reset Diode 12 Resistor 13 Scan Circuit 14 PDP
25 dotted line frame 25A1 dotted line frame 25A2 dotted line frame 31 diode 39 diode 100 electrode drive circuit 100A electrode drive circuit 110 sustain circuit 120 power recovery circuit 120A power recovery circuit 130 bidirectional switch circuit 130A bidirectional switch circuit

Claims (6)

  Connected to the panel electrode through a coil and a bidirectional switch circuit consisting of a semiconductor switch and a high-speed diode from a voltage source that is almost half the discharge sustain voltage of the plasma display panel, between this panel electrode and the discharge sustain power source, and between the reference potential A semiconductor switch is connected, and a series circuit of a diode and a resistor having a discharge sustaining voltage side as a cathode is connected between the discharge sustaining power source from a connection point between the bidirectional switch circuit and the coil, and the connection point A driving circuit for a plasma display panel, wherein a series circuit of a diode and a resistor having a reference potential on the anode side is connected between the reference potentials. In the plasma display panel drive circuit according to claim 1,
A driving circuit for a plasma display panel, wherein the resistance value is 3 to 50Ω. In the plasma display panel drive circuit according to claim 1,
The diode connected between the connection point of the bidirectional switch circuit and the coil, the discharge sustaining power source, and the reference potential is configured as an IC, and a resistor is connected between the IC and the discharge maintaining power source and the reference potential. A driving circuit for a plasma display panel. In a plasma display panel module comprising a plasma display panel, a scan circuit, an X electrode drive circuit, and a Y electrode drive circuit,
The X electrode drive circuit and the Y electrode drive circuit each include a sustain circuit and a power recovery circuit,
The power recovery circuit is connected to a panel electrode through a coil and a bidirectional switch circuit composed of a semiconductor switch and a high-speed diode from a voltage source almost half of the discharge sustain voltage of the plasma display panel. A semiconductor switch is connected between the reference potential and a series circuit of a diode and a resistor having a discharge sustain voltage side as a cathode between a connection point between the bidirectional switch circuit and the coil and a discharge sustain power source, A plasma display panel module comprising a series circuit of a diode and a resistor having a reference potential on the anode side connected between the connection point and a reference potential. The plasma display panel module according to claim 4, wherein
A plasma display panel module, wherein the resistance value of the power recovery circuit is 3 to 50Ω. The plasma display panel module according to claim 4, wherein
The diode connected between the connection point of the bidirectional switch circuit and the coil of the power recovery circuit, the discharge sustaining power source, and the reference potential is configured as an IC, and a resistor is connected between the IC and the discharge maintaining power source and the reference potential. A plasma display panel module, characterized in that is connected.

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