KR100553764B1 - Power supply unit for plasma display device - Google Patents

Abstract

An object of the present invention is to provide a power supply device in which a pulse voltage applied to electrode lines of a plasma display panel is easily changed by an external control signal. In order to achieve the above object, the present invention, a transformer; Switching element for switching the first DC power input to the primary side of the transformer; A feedback signal generator for outputting a feedback signal according to a second DC power output from the secondary side of the transformer; A switching controller for controlling switching of the switching element according to a reference voltage; And a reference voltage controller which generates a reference voltage by comparing the control signal inputted from the outside with the feedback signal and inputs the reference voltage to the switching controller.

Description

Power supply unit for plasma display panel

1 is a block diagram schematically illustrating a role of a power supply device in a plasma display panel.

2 is a circuit diagram showing a conventional power supply for a plasma display panel.

3 is a circuit diagram illustrating an example of a simple feedback signal generator 332.

4 is a schematic diagram of the switching controller 334 for controlling the switching element Q1 of the power supply of the plasma display device.

5 is a perspective view showing the structure of the plasma display panel.

6 is a block diagram illustrating a general driving device of the plasma display panel of FIG. 5.

FIG. 7 is a conceptual diagram illustrating a conventional address-display separation driving method for Y electrode lines of the plasma display panel of FIG. 5.

FIG. 8 is a timing diagram for describing an example of a drive signal of the panel illustrated in FIG. 5.

9 is a circuit diagram of a power supply for a plasma display panel according to an embodiment of the present invention.

10 is a circuit diagram of a reference voltage controller of a power supply according to an embodiment of the present invention.

<Explanation of symbols for main parts of the drawings>

200: image processing unit 202: logic control unit

203: Logic part 205: Panel drive part

204: Y drive unit 206: address drive unit

208: X drive unit 300: power supply unit

330, 430: DC / DC converter 332: feedback signal generator

334: switching control unit 436: reference voltage control unit

Vref: Feedback signal Vref1: Reference voltage

S1: External input signal

The present invention relates to a power supply for a plasma display panel, and more particularly to a power supply that can be applied to the panel by easily varying the pulse voltage of various levels applied to the plasma display panel by applying a control signal. will be.

1 is a block diagram schematically illustrating a role of a power supply device in a plasma display panel.

Referring to the drawings, the plasma display device includes a power supply including a rectifier 311, a power factor corrector 312, a power factor correction controller 313, a DC voltage corrector 320, and a DC / DC converter 330. A device 300, a panel driver 205, and a display panel 1 are provided. The power supply device supplies power to the panel driver 205, and the panel driver 205 discharges a panel by applying a predetermined waveform to scan electrode lines, sustain electrode lines, and address electrode lines of the panel. Causes discharge in the cell.

The rectifier 311, the power factor correcting unit 312, and the DC voltage corrector 320 of FIG. 1 convert an input AC voltage input in an AC form into a DC voltage, and generate a power factor generated in the converted DC voltage. The lowering of the factor) is corrected, and the output DC voltage in the form of DC is output to the DC / DC converter 330 by stepping up or down in the form of the required voltage.

The DC / DC converter 330 receives the DC power from the DC voltage corrector 320 and converts the DC power into DC powers of a plurality of voltages Vs, Va, Ve, Vset, Vscan, ..., and the panel driver. Supply to 205. Hereinafter, a power supply device including the DC / DC converter 330 will be described.

2 is a circuit diagram showing a conventional power supply for a plasma display panel. As shown, the plasma display panel power supply includes a rectifying unit (for example, a rectifying circuit including a smoothing capacitor C1) for converting AC power from the outside into direct current; A transformer T for transforming the DC power rectified through the rectifier into another voltage having a predetermined level and outputting the voltage; And a switching controller 334 for controlling a switching characteristic of the switching element Q1 for applying a pulse signal to the transformer T and adjusting the output voltage of the power output from the transformer. In addition, a feedback signal Vref according to the voltage value of the secondary output voltage is input from the feedback signal generator 332 to the switching controller 334, thereby performing a switching control function of the switching controller 334.

Therefore, the AC voltages V _{1 in} , V _{2 in} ,..., V _{n in} applied from the outside are respectively converted into direct currents of rectifiers including smoothing capacitors, and then the DC / DC conversion mechanism as shown in FIG. 2. Through the switch mode power supply having a power supply for the various DC voltage (Vs, Va, Ve, Vset, Vscan, ...) required for the panel driver 205. The panel driver 205 receives the DC voltages to generate waveforms to be applied to electrode lines of the plasma display panel.

The switching element Q1 and the switching control unit 334 are control devices for maintaining various output DC voltages Vs, Va, Ve, Vset, Vscan, ... in a desired waveform. Voltage regulation switching is performed by a voltage distribution circuit and switching elements (e.g., MOS type field effect transistors, insulated gate bipolar transistors, thyristors, etc.). When the switching element starts the switching action, the energy of the alternating current is induced from the primary winding of the transformer to the secondary winding, and the energy induced in the secondary winding is the diode (D ₁ ) and the smoothing capacitor (C ₂ ). It is output as a power supply having a direct current output voltage (V _out ) according to the turns ratio of the primary side and the secondary side of the transformer through the through.

The switching controller 334 controls the switching characteristics (switching frequency and on / off time) of the switching element Q1 according to the feedback signal Vref received from the feedback signal generator 332.

3 is a circuit diagram illustrating an example of a simple feedback signal generator 332. In FIG. 3, the feedback signal Vref is generated from a voltage distribution circuit with respect to the output voltage. As an example, the voltage Vref of the feedback signal is generated and output as follows.

Vref = (R2 + R3) / (R2 + R3 + R1) × Vout ... (Equation 1)

In FIG. 3, R2 is a variable resistor whose resistance R2 is varied by a variable resistance control signal input from the outside. Vref changes as the resistor R2 varies, and the switching controller 334 controls the switching characteristic of the switching element Q1 according to Vref. The variable resistance control signal may be supplied from a logic controller or an independent microprocessor.

4 is a schematic diagram of the switching controller 334 for controlling the switching element Q1 of the power supply of the plasma display device. The switching controller 130 outputs a pulse width modulation waveform having a predetermined frequency and duty to drive a switch mode power supply to control a DC power of a predetermined value.

The DC power source changed in the smoothing capacitor operates a control unit that performs, for example, pulse width modulation through a starting resistor. The switching element starts a switching action by the pulse width modulation waveform output from the control unit. When the switching element starts the switching action, the energy of the alternating current is maintained from the primary winding of the transformer to one or more secondary windings, and the energy induced in the secondary winding is again converted into the diode D ₁ and the smoothing capacitor C ₂ ) Is converted into DC power according to the turns ratio of the primary side and the secondary side of the transformer to be output as the DC output voltage (V _out ). Here, the switching controller 334 receives the feedback signal Vref according to the output voltage of the switch mode power supply and receives a control signal according to the change of the value thereof, thereby setting the output voltage of the switch mode power supply to a predetermined level. It serves to maintain. That is, when the switch control unit 334 is a secondary side voltage (V _out) of the DC power supply to reduce the duty of the waveform output when the increases, whereas the switch mode, the voltage output from the power supply becomes small by increasing the duty of the waveform In this case, the output voltage of the switch mode power supply is kept constant at a predetermined level. Secondary output voltages (Vs, Va, Ve, Vset, Vscan, ...) are divided by resistors (R ₁ , R ₂ , R _VR ) and applied to an integrated circuit including a Zener diode, and applied feedback signal. The potential of is compared with the ground potential, and the error amount is applied to the switching element Q1 on the primary side through the photocoupler to adjust the pulse width according to the output voltage to maintain a predetermined output voltage.

In the power supply apparatus according to the related art, as described above, the feedback signal Vref according to the secondary side output voltage is input to the switching controller 334 to adjust the switching characteristics of the primary side switching element Q1. That is, the feedback signal Vref is changed by adjusting the variable resistance of the feedback signal generator 332, and the switching characteristic of the primary switching element Q1 is adjusted by the changed feedback signal Vref.

However, pulses with various voltage levels such as Vs, Va, Ve, Vset, and Vscan applied to the plasma display panel need to be changed in accordance with the necessity for the product to actively convert the output, experimental and manufacturing needs. However, according to the conventional power supply, it is not possible to convert the output of the panel quickly and actively in applying the plasma display panel while changing the voltage level of these pulses. Applying while changing is very inconvenient and cumbersome. Therefore, there is a need for a power supply that can output while varying the output voltage through an external control signal supplied in software.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art, and an object of the present invention is to provide a power supply device in which a pulse voltage applied to electrode lines of a plasma display panel is easily changed by an external control signal. .

A plasma display panel power supply apparatus according to the present invention for achieving the above object, a transformer;

Switching element for switching the first DC power input to the primary side of the transformer;

A feedback signal generator for outputting a feedback signal according to a second DC power output from the secondary side of the transformer;

A switching controller for controlling switching of the switching element according to a reference voltage; And

And a reference voltage controller configured to generate a reference voltage by comparing an externally input control signal with the feedback signal and input the reference voltage to the switching controller.

The feedback signal generator outputs a feedback signal proportional to the voltage of the second DC power supply.

The reference voltage controller generates a reference voltage proportional to a voltage difference between the voltage of the feedback signal and the control signal input from the outside. At this time, the voltage of the external control signal is greater than zero and less than the voltage of the feedback signal.

On the other hand, the switching control unit may control the switching of the switching element so that the voltage of the second DC power supply inversely proportional to the magnitude of the reference voltage, on the other hand, the switching control unit is the magnitude of the reference voltage The switching of the switching element may be controlled to increase the voltage of the second DC power in proportion to.

Hereinafter, the configuration and operation of a display panel driving method according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

5 is a diagram illustrating a structure of a plasma display panel.

Referring to FIG. 5, between the front and rear glass substrates 100 and 106 of the conventional surface discharge plasma display panel 1, the address electrode lines A ₁ , A ₂ ,..., A _m , Dielectric layers 102 and 110, Y electrode lines Y ₁ , ..., Y _n , X electrode lines X ₁ , ..., X _n , fluorescent layer 112, barrier rib 114, and As a protective layer, the magnesium monoxide (MgO) layer 104 is provided, for example.

The X electrode lines X ₁ , ..., X _n and the Y electrode lines Y ₁ , ..., Y _n are address electrode lines A ₁ , A ₂ , ..., A _m . It is formed in a predetermined pattern on the back of the front glass substrate 100 to be orthogonal to the. Each intersection sets a corresponding display cell.

A driving scheme generally applied to such a plasma display panel is a method in which initialization, address, and display holding steps are sequentially performed in a unit sub-field. In the initialization step, the charge states of the display cells to be driven are made uniform. In the address step, the charge state of display cells to be selected and the charge state of display cells not to be selected are set. In the display holding step, display discharge is performed in the display cells to be selected. At this time, a plasma is formed from the plasma forming gas of the display cells performing display discharge, and the fluorescent layer 112 of the display cells is excited by ultraviolet radiation from the plasma to generate light.

6 illustrates a general driving device of the plasma display panel of FIG. 5.

Referring to the drawings, a typical driving device of the plasma display panel 1 includes an image processor 200, a controller 202, an address driver 206, an X driver 208, and a Y driver 204.

The image processing unit 200 converts an external analog image signal into a digital signal, and thus internal image signals, for example, 8-bit red (R), green (G), and blue (B) image data, clock signals, vertical and horizontal, respectively. Generate sync signals.

The logic controller 202 generates the drive control signals SA, SY, and SX according to the internal image signal from the image processor 200. The address driver 206 processes the address signal SA among the drive control signals SA, SY, and SX from the controller 202 to generate a display data signal, and generates the display data signal through the address electrode lines. To apply. The X driver 208 processes the X driving control signal SX among the driving control signals SA, SY, and SX from the controller 202 and applies the X driving control signal SX to the X electrode lines. The Y driver 204 processes the Y driving control signal SY among the driving control signals SA, SY, and SX from the controller 202 and applies the Y driving control signal SY to the Y electrode lines.

The power supply unit 300 supplies power at a level required for each circuit unit, and the operating voltages Vs, Va, Ve, Generates and supplies power at the level of Vset, Vscan, etc.

On the other hand, as a driving method of the plasma display panel 1 having the above-described structure, an address-display separation driving method mainly used is disclosed in US Patent No. 5,541,618.

FIG. 7 illustrates a conventional address-display separation driving method for the Y electrode lines of the plasma display panel of FIG. 5.

Referring to the drawings, a unit frame may be divided into a predetermined number, for example, eight subfields SF1, ..., SF8 to realize time division gray scale display. Each subfield SF1, ..., SF8 is divided into a reset section (not shown), an address section A1, ..., A8, and a sustain discharge section S1, ..., S8. do.

In each address section A1, ..., A8, a display data signal is applied to the address electrode lines AR1, AG1, ..., AGm, ABm in FIG. Scan pulses corresponding to..., Yn) are sequentially applied.

In each sustain discharge section S1, ..., S8, pulses for display discharge alternately in the Y electrode lines Y1, ..., Yn and the X electrode lines X1, ..., Xn. Is applied to cause display discharge in discharge cells in which wall charges are formed in the address periods A1, ..., A8.

The luminance of the plasma display panel is proportional to the number of sustain discharge pulses in the sustain discharge sections S1, ..., S8 occupied in the unit frame. When one frame forming one image is represented by eight subfields and 256 gray levels, each subfield is sequentially held at a ratio of 1, 2, 4, 8, 16, 32, 64, and 128 in order. The number of pulses can be assigned. In order to obtain luminance of 133 gray levels, cells may be addressed and sustained and discharged during the subfield 1 period, the subfield 3 period, and the subfield 8 period.

FIG. 8 is a timing diagram for explaining an example of a driving signal of the panel shown in FIG. 5, in which an address electrode A, a common electrode X, and a scan electrode are located in one subfield SF in an ADS driving method of an AC PDP. The drive signal applied to (Y1 to Yn) is shown. Referring to FIG. 4, one subfield SF includes a reset period PR, an address period PA, and a sustain discharge period PS.

The reset period PR initializes the wall charge state of all cells by applying reset pulses to the scan lines of all groups and forcibly performing a write discharge. The reset period PR is performed before entering the address period PA, which is carried out over the entire screen, thus making it possible to create a wall distribution of wall charges with a fairly even and desired distribution. The cells initialized by the reset period PR have similar wall charge conditions in the cells. The address period PA is performed after the reset period PR is performed. At this time, in the address period PA, the bias voltage Ve is applied to the common electrode X, and the scan electrodes Y1 to Yn and the address electrodes A1 to Am are simultaneously turned on at the cell positions to be displayed. Select the display cell. After the address period PA is performed, the sustain pulse Vs is alternately applied to the common electrodes X and the scan electrodes Y1 to Yn to perform the sustain discharge period PS. During the sustain discharge period PS, a low level voltage VG is applied to the address electrodes A1 to Am. In PDP, the brightness is adjusted by the number of sustain discharge pulses. If the number of sustain discharge pulses in one subfield or one TV field is large, the luminance increases.

As can be seen in the timing diagram of FIG. 8, the waveforms applied to the electrode lines of the plasma display panel have various levels such as Vs, Va, Ve, Vset, and Vscan.

9 is a circuit diagram of a power supply for a plasma display panel according to an embodiment of the present invention. The power supply for the plasma display panel disclosed in FIG. 9 includes a transformer T, a switching element Q1, a feedback signal generator 332, a switching controller 334, and a reference voltage controller 436. The capacitor C1 on the primary side and the diode D1 and capacitor C2 on the secondary side are for enhancing voltage smoothness, and the number thereof may be increased as necessary.

The transformer T is a transformer for a switch mode power supply, and has a characteristic suitable for converting a rectangular pulse voltage applied from the primary side into a rectangular pulse voltage of another level. The switching element Q1 connected to the lower end of the transformer T switches the first DC power at a predetermined frequency and / or on / off time according to a control signal applied from the switching controller 334. According to the switching characteristic of the switching element Q1, the square pulse voltage of the converted voltage level is output to the secondary side of the transformer T.

The feedback signal generator 332 connected in parallel at the secondary side of the transformer T generates a feedback signal Vref having a voltage proportional to the secondary voltage V _out induced at the transformer secondary output side. The feedback signal generator 332 of FIG. 9 may be configured in the same way as the circuit configuration of FIG. 3, but is not necessarily limited thereto. The feedback signal Vref having a voltage proportional to the output voltage V _out of the secondary side may be used. Anything that generates) may be used.

The switching controller 334 adjusts the switching of the switching element according to the reference voltage Vref1 generated by the feedback signal Vref and the external input signal S1 from the reference voltage controller 436. According to the reference voltage (Vref1) input from 436 serves to maintain the output voltage of the switch mode power supply to a predetermined level.

The reference voltage controller 436 generates a reference voltage Vref1 by comparing the externally input control signal S1 with the feedback signal Vref. Then, a signal having a reference voltage Vref1 is input to the switching controller 334.

In this case, for example, the switching controller 334 reduces the duty of the waveform output when the reference voltage Vref1 received from the reference voltage controller 436 becomes large, and conversely, receives the input from the reference voltage controller 436. When the reference voltage Vref1 decreases, the switching characteristic of the switching element Q1 is changed to increase the duty of the waveform, thereby converting the output voltage of the switch mode power supply to a predetermined level. That is, the switching controller 334 may control the switching of the switching element Q1 such that the voltage V _out of the second DC power supply increases in inverse proportion to the magnitude of the reference voltage Vref1. On the other hand, the switching controller 334 increases the duty of the waveform output when the reference voltage Vref1 received from the reference voltage controller 436 increases, and conversely, the reference received from the reference voltage controller 436. When the voltage Vref1 decreases, the switching characteristic of the switching element Q1 is changed to reduce the duty of the waveform, thereby converting the output voltage of the switch mode power supply to a predetermined level. That is, the switching controller 334 may control the switching of the switching element Q1 such that the voltage of the second DC power supply increases in proportion to the magnitude of the reference voltage Vref1.

Secondary output voltages (Vs, Va, Ve, Vset, Vscan, ...) generated by the switching control of the switching controller 334 are divided by the resistors R ₁ , R ₂ , R _VR to generate a Zener diode. It is applied to the integrated circuit, and compares the applied reference voltage with the ground potential, and applies the error amount to the switching element Q1 on the primary side through the photocoupler to adjust the pulse width according to the output voltage, thereby providing a predetermined output voltage. Keep it. The switching controller 334 may be the same as the circuit configuration of FIG. 4, but is not necessarily limited thereto.

The external control signal S1 may be input from the logic unit 203 of FIG. 6 or a separate microprocessor, and the second DC power supply V _out may be the Y driver 204, the address driver 206 of FIG. 6, or the like. It may be output to the X driver 208 or the like.

10 is a circuit diagram of a reference voltage controller 436 of a power supply according to an embodiment of the present invention. The reference voltage controller 436 receives a feedback signal Vref from the feedback signal generator 332 and an external control signal S1 input from the logic unit 203 or a microprocessor, and receives a voltage proportional thereto. It may include an output differential amplifier. In FIG. 10, assuming that R1 = R3 and R2 = R4, the reference voltage Vref1 output from the reference voltage controller 436 is as follows.

...(식 2)

... (Equation 2)

At this time, 0 <S1 <Vref. That is, the voltage of the external control signal S1 is greater than zero and smaller than the voltage of the feedback signal Vref.

According to Equation 2, the reference voltage Vref1 output from the feedback signal generator 332 is proportional to the voltage difference between the feedback signal Vref and the external control signal S1. In this case, the external control signal S1 is received in software from the logic unit 203 or the microprocessor. The logic unit 203 or the microprocessor for applying the external control signal S1 should include a waveform of the external control signal S1 so as to adjust the voltage V _out of the second DC power supply.

The best embodiments have been disclosed in the drawings and specification above. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the plasma display panel power supply apparatus according to the present invention has the following effects.

First, according to the power supply apparatus for a plasma display panel according to the present invention, pulse voltages Vs and Va applied to scan (Y) electrode lines, common (X) electrode lines, and address electrode lines of the plasma display panel. , Ve, Vset, Vscan, ... can be easily changed by the external control signal S1.

Second, pulses having various voltage levels applied to the plasma display panel can be applied to the panel electrode lines while varying through an external control signal, thereby quickly and actively converting the output of the panel.

Third, an external control signal for adjusting pulses having various voltage levels applied to the panel can be easily defined and changed by being programmed in a logic unit or a microprocessor or the like, which is very convenient for experimentation and manufacturing process and speed of development. To improve.

The invention is not limited to the examples described above and represented in the drawings. Those skilled in the art taught by the above-described embodiments, many modifications to the above-described embodiments are possible by substitution, erasure, merging, etc. within the scope and object of the present invention described in the following claims.

Claims (6)

Transformers; Switching element for switching the first DC power input to the primary side of the transformer; A feedback signal generator for outputting a feedback signal according to a second DC power output from the secondary side of the transformer; A switching controller for controlling switching of the switching element according to a reference voltage; And a reference voltage controller for generating a reference voltage by comparing an externally input control signal with the feedback signal and inputting the reference voltage to the switching controller. The method of claim 1, The feedback signal generator outputs a feedback signal proportional to the voltage of the second DC power supply. The method of claim 1, And the reference voltage controller generates a reference voltage proportional to a voltage difference between the voltage of the feedback signal and the externally input control signal. The power supply device for a plasma display panel of claim 3, wherein the voltage of the external control signal is greater than zero and less than the voltage of the feedback signal. The method of claim 3, And the switching controller controls the switching of the switching element such that the voltage of the second DC power is increased in inverse proportion to the magnitude of the reference voltage. The method of claim 3, And the switching controller controls the switching of the switching element so that the voltage of the second DC power is increased in proportion to the magnitude of the reference voltage.

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