KR100503730B1 - Apparatus and Method of Energy Recovery - Google Patents

Abstract

The present invention relates to an energy recovery device capable of reducing manufacturing costs.

The energy recovery apparatus of the present invention is for capacitive loads equivalently formed between a scan electrode and a sustain electrode, for recovering and storing energy from the capacitive loads, and for resupplying the stored energy to the capacitive loads. An energy recovery unit including a source capacitor, and between the energy recovery unit and the capacitive load to relay energy between the energy recovery unit and the capacitive load and to generate stable discharge at the capacitive load. And an energy supply unit for supplying a reference voltage to the capacitive load, and an energy relay unit installed between the energy recovery unit and the energy supply unit to relay energy between the energy recovery unit and the energy supply unit.

Description

Apparatus and Method of Energy Recovery

The present invention relates to an energy recovery apparatus and method, and more particularly, to an energy recovery apparatus and method for reducing the manufacturing cost.

Plasma Display Panels (hereinafter referred to as "PDPs") are characterized by emitting phosphors by 147 nm ultraviolet rays generated during discharge of an inert mixed gas such as He + Xe, Ne + Xe or He + Ne + Xe. An image containing graphics is displayed. Such a PDP is not only thin and easy to enlarge, but also greatly improved in quality due to recent technology development. In particular, the three-electrode AC surface discharge type PDP has advantages of low voltage driving and long life because wall charges are accumulated on the surface during discharge and protect the electrodes from sputtering caused by the discharge.

1 is a perspective view illustrating a discharge cell structure of a conventional plasma display panel.

Referring to FIG. 1, a discharge cell of a three-electrode AC surface discharge type PDP includes a scan electrode Y and a sustain electrode Z formed on the upper substrate 10, and an address electrode formed on the lower substrate 18. X). Each of the scan electrode Y and the sustain electrode Z has a line width smaller than the line widths of the transparent electrodes 12Y and 12Z and the transparent electrodes 12Y and 12Z and is formed at one edge of the transparent electrode 13Y, 13Z).

The transparent electrodes 12Y and 12Y are usually formed on the upper substrate 10 by indium tin oxide (ITO). The metal bus electrodes 13Y and 13Z are usually formed of metals such as chromium (Cr) and formed on the transparent electrodes 12Y and 12Z to reduce voltage drop caused by the transparent electrodes 12Y and 12Z having high resistance. The upper dielectric layer 14 and the passivation layer 16 are stacked on the upper substrate 10 having the scan electrode Y and the sustain electrode Z side by side. In the upper dielectric layer 14, wall charges generated during plasma discharge are accumulated. The protective layer 16 prevents damage to the upper dielectric layer 14 due to sputtering generated during plasma discharge and increases emission efficiency of secondary electrons. As the protective film 16, magnesium oxide (MgO) is usually used.

The lower dielectric layer 22 and the partition wall 24 are formed on the lower substrate 18 on which the address electrode X is formed, and the phosphor layer 26 is coated on the surfaces of the lower dielectric layer 22 and the partition wall 24. The address electrode X is formed in the direction crossing the scan electrode Y and the sustain electrode Z. The partition wall 24 is formed in a stripe or lattice shape to prevent the ultraviolet rays and the visible light generated by the discharge from leaking to the adjacent discharge cells. The phosphor layer 26 is excited by ultraviolet rays generated during plasma discharge to generate visible light of any one of red, green, and blue. Inert mixed gas is injected into the discharge space provided between the upper and lower substrates 10 and 18 and the partition wall 24.

The three-electrode AC surface discharge type PDP is driven by being divided into a plurality of subfields, and gray scale display is performed by emitting light a number of times proportional to the weight of video data in each subfield period. The plurality of subfields are driven by being divided into reset periods, address periods, sustain periods, and erase periods.

Here, the reset period is a period in which uniform wall charges are formed in the discharge cells, the address period is a period in which selective address discharge occurs in accordance with the logic value of the video data, and the sustain period is a discharge cell in which the address discharge has occurred. Is a period for maintaining the discharge.

The address discharge and the sustain discharge of the AC surface discharge PDP driven in this way require a high voltage of several hundred volts or more. Therefore, an energy recovery apparatus is used to minimize the driving power required for the address discharge and the sustain discharge. The energy recovery apparatus recovers the voltage between the scan electrode Y and the sustain electrode Z and uses the voltage recovered as the driving voltage at the next discharge.

FIG. 2 is a view showing an energy recovery device formed on the scan electrode Y in order to volatilize the sustain discharge voltage. In practice, the energy recovery device is symmetrically installed on the sustain electrode Z with respect to the panel capacitor Cp.

Referring to FIG. 2, a conventional energy recovery apparatus includes an inductor L connected between a panel capacitor Cp and a source capacitor Cs, and a parallel connection between the source capacitor Cs and the inductor L in parallel. The first and third switches S1 and S3, the diodes D5 and D6 installed between the first and third switches S1 and S3 and the inductor L, the inductor L and the panel capacitor Cp. ) And second and fourth switches S2 and S4 connected in parallel.

The panel capacitor Cp equivalently represents the capacitance formed between the scan electrode Y and the sustain electrode Z. FIG. The second switch S2 is connected to the reference voltage source Vs, and the fourth switch S4 is connected to the ground voltage source GND. The source capacitor Cs recovers and charges the voltage charged to the panel capacitor Cp during the sustain discharge, and supplies the charged voltage to the panel capacitor Cp again.

To this end, the source capacitor Cs has a capacitance value capable of charging a voltage of Vs / 2 corresponding to half of the reference voltage source Vs. The inductor L forms a resonance circuit together with the panel capacitor Cp. The first to fourth switches S1 to S4 control the flow of current. The fifth and sixth diodes D5 and D6 prevent current from flowing in the reverse direction. In addition, the internal internal diodes D1 to D4 respectively installed in the first to fourth switches S1 to S4 also prevent the reverse current from flowing.

3 is a timing diagram and waveform diagrams illustrating on / off timings of the switches illustrated in FIG. 2 and output waveforms of the panel capacitor.

The operation process will be described in detail assuming that the panel capacitor Cp is charged with a voltage of 0 volts and the source capacitor Cs is charged with a voltage of Vs / 2 before the T1 period.

In the T1 period, the first switch S1 is turned on to form a current path from the source capacitor Cs to the first switch S1, the inductor L, and the panel capacitor Cp. When the current path is formed, the voltage of Vs / 2 charged in the source capacitor Cs is supplied to the panel capacitor Cp. At this time, since the inductor L and the panel capacitor Cp form a series resonant circuit, the panel capacitor Cp is charged with a Vs voltage that is twice the voltage of the source capacitor Cs.

In the T2 period, the second switch S2 is turned on. When the second switch S2 is turned on, the voltage of the reference voltage source Vs is supplied to the panel capacitor Cp. That is, when the second switch S2 is turned on, the voltage value of the reference voltage source Vs is supplied to the panel capacitor Cp to prevent the voltage value of the panel capacitor Cp from falling below the reference voltage source Vs. Thus, sustain discharge is stably generated. Here, since the voltage of the panel capacitor Cp has risen to Vs in the period T1, the voltage value supplied from the outside during the period T2 can be minimized (that is, the power consumption can be reduced).

In the T3 period, the first switch S1 is turned off. In this case, the panel capacitor Cp maintains the voltage of the reference voltage source Vs. In the T4 period, the second switch S2 is turned off and the third switch S3 is turned on. When the third switch S3 is turned on, a current path is formed from the panel capacitor Cp to the source capacitor Cs through the inductor L and the third switch S3 to charge the panel capacitor Cp. The voltage is recovered to the source capacitor Cs. At this time, the source capacitor Cs is charged with a voltage of Vs / 2.

In the T5 period, the third switch S3 is turned off and the fourth switch S4 is turned on. When the fourth switch S4 is turned on, a current path is formed between the panel capacitor Cp and the base voltage source GND, so that the voltage of the panel capacitor Cp drops to zero volts. In the T6 period, the state of T5 is maintained for a certain time. In fact, the AC drive pulses supplied to the scan electrode Y and the sustain electrode Z are obtained by periodically repeating the periods T1 to T6.

However, in order to install such a conventional energy recovery device, a large manufacturing cost is generated. In detail, the devices (diodes, switching devices, etc.) used in the conventional energy recovery apparatus should have a breakdown voltage that can withstand the voltage value of the reference voltage source Vs. In addition, the fifth and sixth diodes D5 and D6 should have a fast response speed. Therefore, since a large number of devices having a fast response speed and high breakdown voltage are conventionally used, a large manufacturing cost is consumed.

Accordingly, it is an object of the present invention to provide an energy recovery apparatus and method that can reduce manufacturing costs.

In order to achieve the above object, the energy recovery apparatus of the present invention has a capacitive load equivalently formed between a scan electrode and a sustain electrode, and recovers and stores energy from the capacitive load and stores the energy stored therein. An energy recovery unit including a source capacitor for resupplying the load, and installed between the energy recovery unit and the capacitive load to relay energy between the energy recovery unit and the capacitive load, An energy supply unit for supplying a reference voltage to the capacitive load, and between the energy recovery unit and the energy supply unit to relay energy between the energy recovery unit and the energy supply unit so that a stable discharge can be generated under And an energy relay unit. The energy recovery unit includes the source capacitor. And a first switching device disposed between the capacitor and the base voltage source and turned on when energy charged in the source capacitor is supplied to the energy relay unit. The energy supply unit is connected to a reference voltage source for supplying a reference voltage. And a second switching element, and third and fourth switching elements connected in parallel between the second switching element and the ground voltage source.

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The energy relay includes a magnetic coupling inductor in which at least two coils are magnetically coupled.

The magnetic coupling inductor includes a first inductor provided between the first switching element and the source capacitor, and a second inductor provided between the second switching element and the third switching element.

And an internal diode installed inside the first switch to form a current path so that energy charged in the first inductor can be supplied to the source capacitor.

The third switching element is turned on when the second inductor is charged using energy charged in the capacitive load.

An internal diode is provided inside the third switching element and forms an electric current path so that energy charged in the second inductor can be supplied to the panel capacitor.

The fourth switching element is turned on when the ground potential is supplied to the capacitive load.

The coils of the first inductor and the second inductor are wound in the same direction.

The coils of the first inductor and the second inductor are wound in different directions.

The energy recovery method of the present invention uses a first step of charging a first inductor of a magnetic coupling inductor using energy charged in a source capacitor, and energy is supplied to a second inductor of the magnetic coupling inductor when energy is charged in the first inductor. And a third step of supplying the energy charged in the second inductor to the capacitive load equivalently formed between the scan electrode and the sustain electrode.

The energy charged in the second inductor is supplied as a capacitive load when the energy supplied to the first inductor is cut off.

The energy charged in the second inductor is charged and supplied to the capacitive load.

In the third step, the reference voltage is charged to the capacitive load.

And after the third step, supplying the voltage value of the reference voltage source as the capacitive load for a predetermined time.

A fourth step of charging the second inductor by using the energy charged in the capacitive load, a fifth step of charging energy in the first inductor when energy is charged in the second inductor, and energy charged in the first inductor Further comprising a sixth step of charging the source capacitor using.

The energy charged in the first inductor is supplied to the source capacitor when the energy supplied to the second inductor is cut off.

The energy charged in the first inductor is charged and supplied to the source capacitor.

Other objects and features of the present invention in addition to the above objects will become apparent from the description of the embodiments with reference to the accompanying drawings.

Hereinafter, exemplary embodiments of the present invention will be described with reference to FIGS. 4 to 7.

4 is a view showing an energy recovery apparatus according to an embodiment of the present invention. In FIG. 4, the energy recovery device is shown only on one side of the panel capacitor Cp. In fact, the energy recovery devices are symmetrically installed on both sides of the panel capacitor Cp.

Referring to FIG. 4, the energy recovery apparatus according to the embodiment of the present invention includes an energy (voltage and / or current) recovery unit 30, an energy supply unit 32, and an energy relay unit 34.

The energy recovery unit 30 recovers energy from the energy supply unit 32 and supplies the recovered energy back to the energy supply unit 32. To this end, the energy recovery unit 30 includes a source capacitor Cs and a first switch S1. The source capacitor Cs recovers and charges the voltage charged in the panel capacitor Cp during the sustain discharge, and supplies the charged voltage to the panel capacitor Cp again. The first switch S1 is turned on when energy is supplied to the energy relay 34. Here, an internal diode D1 is installed in the first switch S1 to prevent reverse current. An energy relay 34 is installed between the first switch S1 and the source capacitor Cp.

The energy supply unit 32 is connected to the reference voltage source Vs, the base voltage source GND, and the panel capacitor Cp. The energy supply unit 32 supplies energy supplied from the energy relay unit 34 to the panel capacitor Cp and re-supplies energy supplied from the panel capacitor Cp to the energy relay unit 34. In addition, the energy supply unit 32 supplies the voltage value of the reference voltage source Vs to the panel capacitor Cp.

To this end, the energy supply unit 32 includes a third switch S3 connected to the reference voltage source Vs, and second and fourth switches connected in parallel between the third switch S3 and the base voltage source GND. S2, S4). An energy relay unit 34 is installed between the second switch S2 and the third switch S3. The third switch S3 is turned on when the reference voltage Vs is supplied to the panel capacitor Cp. The second switch S2 is turned on when the voltage charged in the panel capacitor Cp is recovered to the energy recovery unit 30. (The energy charged in the panel capacitor Cp is exactly the energy relay unit 34.) The fourth switch S4 is turned on when the base voltage GND is supplied to the panel capacitor Cp. Each of the second to fourth switches S4 is provided with internal diodes D2 to D4 for preventing reverse current.

The energy relay unit 34 is installed between the energy recovery unit 30 and the energy supply unit 32 to relay energy. To this end, the energy relay 34 includes a transformer. The transformer includes a first inductor L1 (installed between Cs and S1) installed in the energy recovery unit 30 and a second inductor L2 (installed between S2 and Cp) installed in the energy supply unit 32. Equipped. The coils of the first inductor L1 and the second inductor L2 are wound in opposite directions. In addition, the winding ratios of the first inductor L1 and the second inductor L2 are experimentally set so that energy transfer can be performed smoothly. The panel capacitor Cp equivalently represents the capacitance formed between the scan electrode and the sustain electrode.

FIG. 5 is a timing diagram and waveform diagrams illustrating on / off timings of the switches illustrated in FIG. 4 and output waveforms of the panel capacitor.

The operation process will be described in detail assuming that the panel capacitor Cp is charged with a voltage of 0 volts and the source capacitor Cs is charged with a constant voltage before the T1 period.

In the T1 period, the first switch S1 is turned on. When the first switch S1 is turned on, a current path is formed from the source capacitor Cs to the first inductor L1 and the first switch S1 of the transformer. At this time, the first inductor L1 is charged with a current (or energy) supplied from the source capacitor Cs. Meanwhile, when the current is charged in the first inductor L1, the current is also charged in the second inductor L2. However, since the coils of the first inductor L1 and the second inductor L2 are wound in opposite directions, the current charged in the second inductor L2 cannot be supplied to the panel capacitor Cp. Since the internal diode D2 of the switch S2 is located in the reverse direction, the current charged in the first inductor L2 is not supplied to the ground potential GND)

In the T2 period, the first switch S1 is turned off. That is, when a constant current is charged in the first inductor L1 (that is, when the current of the first inductor L1 reaches a predetermined value), the first switch S1 is turned off. When the first switch S1 is turned off, the polarity of the second inductor L2 is reversed. At this time, the current charged in the second inductor L2 is supplied to the panel capacitor Cp. (A current path is formed because the internal diode D2 of the second switch S2 is located in the forward direction.) The T2 period lasts until the panel capacitor Cp is charged with a voltage value of Vs.

In the T3 period, the third switch S3 is turned on. When the third switch S3 is turned on, the voltage value of the reference voltage source Vs is supplied to the panel capacitor Cp to prevent the voltage value of the panel capacitor Cp from falling below the reference low voltage source Vs, As a result, sustain discharge is stably generated. Here, since the voltage value of the panel capacitor Cp has risen to Vs in the T2 period, the voltage value supplied from the outside during the T3 period can be minimized (that is, the power consumption can be reduced).

In the T4 period, the second switch S2 is turned on. When the second switch S2 is turned on, a current path leading to the panel capacitor Cp, the second inductor L2, and the second switch S2 is formed so that the voltage charged in the panel capacitor Cp is second. It is supplied to the inductor L2. At this time, the second inductor L2 is charged with a predetermined current. Meanwhile, when the current is charged in the second inductor L2, the current is also charged in the first inductor L1. However, since the coils of the second inductor L2 and the first inductor L1 are wound in opposite directions, the current charged in the first inductor L1 is not supplied to the source capacitor Cs. Since the internal diode D1 of the switch S1 is located in the reverse direction, the current charged in the first inductor L1 is not supplied to the ground potential GND)

In the period T5, the second switch S2 is turned off. When the second switch S2 is turned off, the polarity of the first inductor L1 is reversed. At this time, the current charged in the first inductor L1 is supplied to the source capacitor Cs. (A current path is formed because the internal diode D1 of the first switch S1 is located in the forward direction.) That is, the source Capacitor Cs recovers energy from panel capacitor Cp via a transformer.

In the period T6, the fourth switch S4 is turned on. When the fourth switch S4 is turned on, the panel capacitor Cp is connected to the ground voltage source GND. In fact, the energy recovery device of the present invention provided on both sides of the panel capacitor Cp alternately repeats the periods of T1 to T6 to supply AC drive pulses to the panel capacitor Cp.

Meanwhile, the energy recovery device of the present invention may not be provided with two diodes D5 and D6 as compared with the conventional energy recovery device shown in FIG. 2. Here, in the present invention, a transformer is installed instead of two diodes D5 and D6, but such a transformer has a lower installation cost than diodes D5 and D6 having high breakdown voltage. Therefore, the production cost is reduced by using the energy recovery device of the present invention.

6 is a view showing an energy recovery apparatus according to another embodiment of the present invention. In FIG. 6, the energy recovery device is shown only on one side of the panel capacitor Cp. In fact, the energy recovery device is installed on both sides symmetrically with respect to the panel capacitor Cp.

Referring to FIG. 6, an energy recovery apparatus according to another embodiment of the present invention includes an energy (voltage and / or current) recovery unit 40, an energy supply unit 42, and an energy relay unit 44.

The energy recovery unit 40 recovers energy from the energy supply unit 42 and re-supplies the recovered energy to the energy supply unit 42. To this end, the energy recovery unit 40 includes a source capacitor Cs and a first switch S1. The source capacitor Cs recovers and charges the voltage charged in the panel capacitor Cp during the sustain discharge, and supplies the charged voltage to the panel capacitor Cp again. The first switch S1 is turned on when energy is supplied to the energy relay 44. Here, an internal diode D1 is installed in the first switch S1 to prevent reverse current. An energy relay 44 is provided between the first switch S1 and the source capacitor Cp.

The energy supply 42 is connected to the reference voltage source Vs, the base voltage source GND, and the panel capacitor Cp. The energy supply unit 42 supplies energy supplied from the energy relay unit 44 to the panel capacitor Cp and re-supplies energy supplied from the panel capacitor Cp to the energy relay unit 44. In addition, the energy supply unit 42 supplies the voltage value of the reference voltage source Vs to the panel capacitor Cp.

To this end, the energy supply unit 42 includes a third switch S3 connected to the reference voltage source Vs, and second and fourth switches connected in parallel between the third switch S3 and the ground voltage source GND. S2, S4). An energy relay 44 is installed between the second switch S2 and the third switch S3. The third switch S3 is turned on when the reference voltage Vs is supplied to the panel capacitor Cp. The second switch S2 is turned on when the voltage charged in the panel capacitor Cp is recovered to the energy recovery unit 30. (The energy charged in the panel capacitor Cp is exactly the energy relay unit 44.) The fourth switch S4 is turned on when the base voltage GND is supplied to the panel capacitor Cp. Each of the second to fourth switches S2 is provided with internal diodes D2 to D4 for preventing reverse current.

The energy relay unit 44 is installed between the energy recovery unit 40 and the energy supply unit 42 to relay energy. To this end, the energy relay 44 includes a transformer. The transformer is provided with a first inductor L1 (installed between Cs and S1) installed in the energy recovery unit 40 and a second inductor L2 (installed between S2 and Cp) installed in the energy supply unit 42. Equipped. The coils of the first inductor L1 and the second inductor L2 are wound in the same direction. In addition, the winding ratios of the first inductor L1 and the second inductor L2 are experimentally set so that energy transfer can be performed smoothly. The panel capacitor Cp equivalently represents the capacitance formed between the scan electrode and the sustain electrode.

FIG. 7 is a timing diagram and waveform diagrams illustrating on / off timing of the switches illustrated in FIG. 6 and an output waveform of the panel capacitor.

The operation process will be described in detail with the assumption that the panel capacitor Cp is charged with a voltage of 0 volts and the source capacitor Cs is charged with a constant voltage before the T1 period.

In the T1 period, the first switch S1 is turned on. When the first switch S1 is turned on, a current path is formed from the source capacitor Cs to the first inductor L1 and the first switch S1 of the transformer. At this time, the first inductor L1 is charged with a current (or energy) supplied from the source capacitor Cs. Meanwhile, when the current is charged in the first inductor L1, the current is also charged in the second inductor L2. At this time, since the coils of the first inductor L1 and the second inductor L2 are wound in the same direction, the current charged in the second inductor L2 is supplied to the panel capacitor Cp. The current path is formed because the internal diode D2 of S2 is located in the forward direction. This T1 period lasts until the panel capacitor Cp is charged with the voltage value of Vs.

In the T2 period, the third switch S3 is turned on. When the third switch S3 is turned on, the voltage value of the reference voltage source Vs is supplied to the panel capacitor Cp to prevent the voltage value of the panel capacitor Cp from falling below the reference low voltage source Vs, As a result, sustain discharge is stably generated. Here, since the voltage value of the panel capacitor Cp rises to Vs in the T1 period, the voltage value supplied from the outside during the T2 period can be minimized (that is, the power consumption can be reduced).

In the T3 period, the second switch S2 is turned on. When the second switch S2 is turned on, a current path leading to the panel capacitor Cp, the second inductor L2, and the second switch S2 is formed, so that the energy charged in the panel capacitor Cp is second. It is supplied to the inductor L2. At this time, the second inductor L2 is charged with a predetermined current. Meanwhile, when the current is charged in the second inductor L2, the current is also charged in the first inductor L1. At this time, since the coils of the second inductor L2 and the first inductor L1 are wound in the same direction, the current charged in the first inductor L1 is supplied to the source capacitor Cs. Since the internal diode D1 of the switch S1 is located in the forward direction, a current path is formed), that is, the source capacitor Cs recovers energy from the panel capacitor Cp via the transformer.

In the T4 period, the fourth switch S4 is turned on. When the fourth switch S4 is turned on, the panel capacitor Cp is connected to the ground voltage source GND. In fact, the energy recovery device of the present invention provided on both sides of the panel capacitor Cp alternately repeats the periods of T1 to T4 to supply AC drive pulses to the panel capacitor Cp.

On the other hand, the energy recovery device according to another embodiment of the present invention may not be provided with two diodes (D5, D6) compared to the conventional energy recovery device shown in FIG. Here, in the present invention, the transformer 34 is installed in place of the two diodes D5 and D6, but such a transformer 34 has a lower installation cost than the diodes D5 and D6 having higher breakdown voltages. Therefore, the production cost is reduced by using the energy recovery device of the present invention.

As described above, according to the energy recovery apparatus and method according to the present invention, since a transformer is installed to relay energy between the source capacitor and the panel capacitor, a diode is not additionally installed, thereby reducing manufacturing costs.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

1 is a perspective view showing a discharge cell structure of a conventional three-electrode AC surface discharge type plasma display panel.

2 is a circuit diagram showing a conventional energy recovery device.

FIG. 3 is a timing diagram illustrating on-off timing of switches included in the energy recovery device shown in FIG. 2.

4 is a circuit diagram showing an energy recovery apparatus according to an embodiment of the present invention.

FIG. 5 is a timing diagram illustrating on-off timing of switches included in the energy recovery device illustrated in FIG. 4.

6 is a circuit diagram showing an energy recovery apparatus according to another embodiment of the present invention.

FIG. 7 is a timing diagram illustrating on-off timing of switches included in the energy recovery device illustrated in FIG. 6.

<Description of Symbols for Main Parts of Drawings>

10: upper substrate 12Y, 12Z: transparent electrode

13Y, 13Z: bus electrode 14, 22: dielectric layer

16: protective film 18: lower substrate

24: partition 26: phosphor layer

30,40: energy recovery unit 32,42: energy supply unit

34,44: energy relay

Claims (19)

A capacitive load equivalently formed between the scan electrode and the sustain electrode, An energy recovery unit including a source capacitor for recovering and storing energy from the capacitive load and resupplying the stored energy to the capacitive load; The reference voltage is provided between the energy recovery unit and the capacitive load so as to relay energy between the energy recovery unit and the capacitive load and to generate stable discharge at the capacitive load. An energy supply unit for supplying, And an energy relay unit disposed between the energy recovery unit and the energy supply unit to relay energy between the energy recovery unit and the energy supply unit. The method of claim 1, The energy recovery unit, And a first switching device disposed between the source capacitor and the base voltage source and turned on when the energy charged in the source capacitor is supplied to the energy relay unit. The method of claim 2, The energy supply unit A second switching element connected to a reference voltage source for supplying the reference voltage; And third and fourth switching elements connected in parallel between the second switching element and the base voltage source. The method of claim 3, wherein The energy relay unit, And at least two coils have magnetically coupled inductors magnetically coupled. The method of claim 4, wherein The magnetic coupling inductor, A first inductor provided between the first switching element and the source capacitor; And a second inductor provided between the second switching element and the third switching element. The method of claim 5, And an internal diode installed in the first switch to form a current path so that energy charged in the first inductor can be supplied to the source capacitor. The method of claim 5, And the third switching device is turned on when the second inductor is charged using energy charged in the capacitive load. The method of claim 7, wherein And an internal diode provided inside the third switching element and forming a current path so that energy charged in the second inductor can be supplied to the panel capacitor. The method of claim 3, wherein And said fourth switching element is turned on when a ground potential is supplied to said capacitive load. The method of claim 5, And the coils of the first inductor and the second inductor are wound in the same direction. The method of claim 5, And the coils of the first inductor and the second inductor are wound in different directions. In the energy recovery method comprising a reference voltage source for supplying a reference voltage so that a stable sustain discharge can occur, A first step of charging the first inductor of the magnetic coupling inductor using energy charged in the source capacitor, A second step of charging energy to a second inductor of the magnetic coupling inductor when energy is charged to the first inductor; And a third step of supplying the energy charged in the second inductor to a capacitive load that is equivalently formed between the scan electrode and the sustain electrode. The method of claim 12, The energy charged in the second inductor is supplied to the capacitive load when the energy supplied to the first inductor is cut off. The method of claim 12, Energy charged in the second inductor is charged and at the same time supplied to the capacitive load energy recovery method. The method of claim 12, In the third step, the energy recovery method characterized in that the reference voltage is charged to the capacitive load. The method of claim 12, And after the third step, supplying the voltage value of the reference voltage source to the capacitive load for a predetermined time. The method of claim 12, A fourth step of charging the second inductor by using the energy charged in the capacitive load; A fifth step of charging energy to the first inductor when energy is charged to the second inductor; And a sixth step of charging the source capacitor using the energy charged in the first inductor. The method of claim 17, The energy charged in the first inductor is supplied to the source capacitor when the energy supplied to the second inductor is cut off. The method of claim 17, Energy charged in the first inductor is charged and supplied to the source capacitor at the same time energy recovery method.