JP2008275915A - Drive device and plasma display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive device of a plasma display panel, which reduces restrictions on a voltage or a waveform applied to the plasma display panel itself and is capable of reducing noise and costs, and to provide a plasma display device. <P>SOLUTION: A sustain pulse X driving circuit 6 is provided with: a circuit which applies a voltage VX1 closer to a ground level than a voltage Vs applied in a reset period and comprises transistors Tr3 and Tr4 and a resistance R1; and a circuit which applies a voltage VX2 closer to the ground level than the voltage VX1 and comprises transistors Tr6 and Tr7 and a resistance R3. The voltage Vs is gradually lowered to the voltage VX1 and the voltage VX2 and finally lowered to the ground level. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a driving device that applies a predetermined waveform or voltage to display electrodes of a plasma display panel, and a plasma display device including the driving device.

  Generally, a plasma display panel is a flat panel display device that displays characters or images using plasma generated by gas discharge. FIG. 1 is an electrode array diagram of a general plasma display panel.

  The electrodes have a matrix configuration of m columns and n rows. Address electrodes (A1 to Am) are arranged in the column direction, and n rows of scan electrodes (Y1 to Yn) and sustain electrodes (X) are arranged in the row direction. A discharge cell as a display element is formed in a discharge space at the intersection of the scan electrode, the sustain electrode, and the address electrode forming a pair. Then, a potential difference in the form of a pulse signal is formed between the sustain electrode and the scan electrode, and discharge occurs, and the vacuum ultraviolet rays generated in this discharge process are red (R), green (G), and blue (B) phosphors of the discharge cell. To emit light.

  The driving method of the plasma display panel having the above-described configuration is described in Patent Documents 1 and 2, for example.

That is, in the conventional plasma display panel driving method, one frame is divided into many subfields having different light emission counts, and each subfield is selected with a reset period for initializing all cells and cells to be discharged. The address period is divided into a sustain period in which gradation is implemented according to the number of discharges. For example, when displaying an image with 256 gradations, one frame period is divided into eight subfields, the reset period and address period of each subfield are the same, and the sustain period is 2 ⁿ ( However, it is set to increase at a rate of n = 0, 1, 2, 3, 4, 5, 6, 7). In this manner, by changing the sustain period in each subfield, the number of sustain discharges is adjusted, and the gradation of the image can be expressed.

During the reset period in each subfield, the discharge characteristics of each discharge cell are stabilized by applying a voltage of a predetermined waveform to the scan electrode, sustain electrode, and address electrode to cause all discharge cells to discharge regardless of the previous display state. It has become. In the address period, in order to perform the ON / OFF operation of the discharge cell according to the display data, the address discharge is performed by the line sequential method. In this address period, first, a scan pulse is applied to the scan electrode, and an address pulse is selectively applied to the address electrode corresponding to the discharge cell that causes a sustain discharge in the address electrode, that is, the discharge cell to be lit. Then, a discharge occurs between the address electrode of the discharge cell to be lit and the scan electrode. During the sustain period, sustain discharge pulses are alternately applied to the sustain electrodes and the scan electrodes to perform sustain discharge, and image display of one subframe is performed.
JP 2004-29851 A JP 2006-227625 A

  In the plasma display panel, a high voltage of several tens to several hundreds of volts is applied to each electrode in order to perform the above-described driving operation. Therefore, depending on the waveform, noise is generated due to a steep current flowing in the drive circuit, and it is necessary to take measures against unnecessary radiation due to this noise. In addition, it is necessary to form a drive circuit with elements such as transistors having a large rating so as to cope with such a steep current, resulting in an increase in cost.

  In the driving method described in Patent Document 1, the potential for selecting the scan electrode in the address period has a voltage equivalent to that of the sustain discharge period, and has a voltage opposite to that of the sustain electrode and equivalent to the voltage of the sustain discharge period. Is applied to the scan electrode. Further, a resistor is inserted in the output stage of the switching element in order to increase the impedance of the switching element. In this way, the address data driver can have a low withstand voltage and a simplified power supply configuration, and can suppress the generation of noise at the falling edge of the sustain discharge pulse, between the address electrode and the scan electrode, and Abnormal discharge is prevented from occurring between the address electrode and the sustain electrode.

  The plasma display device described in Patent Literature 2 applies a setup driving unit that applies a rising pulse to the scan electrode during the reset period, and applies a first falling ramp pulse before the rising pulse is applied to the scan electrode, A set-down driver for applying a second falling ramp pulse after a rising pulse is applied to the scan electrode, and a voltage substantially the same as the voltage of the rising pulse in the scan electrode during the address period after the reset period; By providing a scan pulse driving unit that applies a scan pulse, the high withstand voltage transistor that has been conventionally required is eliminated, thereby reducing the cost.

  However, since the driving method described in Patent Document 1 and the plasma display device described in Patent Document 2 place restrictions on the voltage and waveform applied to the plasma display panel itself, the characteristics of the plasma display panel are improved. This may not be applicable when a drive waveform or voltage that can improve display quality is required. Further, the plasma display device described in Patent Document 2 does not mention noise countermeasures.

  Accordingly, the present invention provides, for example, a driving device and a plasma display device that can reduce the voltage and waveform restrictions applied to the plasma display panel itself, reduce noise, and reduce costs in a plasma display panel driving device. It is an issue to provide.

  In order to solve the above-described problem, the drive device according to claim 1 is a drive device that applies a predetermined voltage to the electrodes of the plasma display panel in order to cause a display element of the plasma display panel to discharge. Voltage applying means for applying a voltage having a potential closer to the ground level than the predetermined voltage to the electrode is provided.

  Hereinafter, a drive device according to an embodiment of the present invention will be described. A driving apparatus according to an embodiment of the present invention includes voltage applying means for applying a voltage having a potential closer to the ground level than a predetermined voltage applied to an electrode of a plasma display panel. In this way, when the potential is dropped from the predetermined voltage to the ground level, the peak current can be dispersed by dropping to the ground level via a potential closer to the ground level than the predetermined voltage. A steep current can be prevented from flowing and noise can be reduced. Further, since the current is reduced, the rating of the element used for the driving device can be lowered, so that the cost can be reduced.

  Moreover, the voltage application means may be comprised with the switching element. By doing so, a voltage having a potential closer to the ground level than a predetermined voltage can be applied to the electrode by switching the switching element.

  In addition, a plurality of switching elements of the voltage applying means may be connected in series. By doing in this way, the electric current by the diode formed in a switching element can be suppressed.

  Further, the voltage applying means may be connected in series with a switching element, a current suppressing means for suppressing a current flowing through the voltage applying means. By doing in this way, since the electric current which flows into a drive device can further be reduced, cost can be reduced.

  Further, a plurality of voltage applying means may be provided, and the plurality of voltage applying means may apply different voltages. By doing so, a predetermined voltage can be set to the ground level via a plurality of potentials, and by providing a plurality of potentials, a waveform required by the specifications of the plasma display panel can be easily generated.

  Further, a control means for switching from a voltage applying means for applying a voltage having a potential close to a predetermined voltage to a voltage applying means for gradually applying a voltage having a potential close to a ground level may be provided for the plurality of voltage applying means. . By doing so, since the peak current can be further dispersed, the steep current does not flow, and the rating of the element used in the driving device can be lowered, so that the cost can be reduced.

  Moreover, you may provide the drive apparatus as described in any one of Claims 1 thru | or 6 in a plasma display apparatus. By doing so, it is possible to reduce noise during the driving operation of the plasma display apparatus and to reduce the cost.

  An embodiment of the present invention will be described with reference to FIGS. A plasma display apparatus 1 according to an embodiment of the present invention includes a plasma display panel 2, a microprocessor 3, a sustain pulse control circuit 4, a sustain pulse Y drive circuit 5, and a sustain pulse. A pulse X drive circuit 6, an address / scan control circuit 7, a scan (scan) drive circuit 8, and an address (data) drive circuit 9 are provided.

  The plasma display panel 2 is an AC PDP (Plasma Display Panel) type panel and has a well-known three-electrode surface discharge structure. In this structure, the address electrodes A1 to Am are arranged on the rear substrate of the PDP in the vertical direction (column direction) of the panel, the scan electrodes Y1 to Yn and the sustain electrodes X are alternately arranged on the front substrate of the PDP, and It is arranged in the horizontal direction (row direction). The address electrodes A1 to Am and the scan electrodes Y1 to Yn can individually change the potential one by one. Discharge cells as display elements (not shown) are installed at intersections between pairs of address electrodes A1 to Am and adjacent scan electrodes Y1 to Yn and sustain electrode X. On the surface of the discharge cell, a layer made of a dielectric (dielectric layer), a layer for protecting the electrode and the dielectric layer (protective layer), and a layer containing a phosphor (fluorescent layer) are provided. Gas is sealed inside the discharge cell. When a discharge occurs in the discharge cell by applying a pulse voltage between the address electrodes A1 to Am, the scan electrodes Y1 to Yn, and the sustain electrode X, the gas molecules are ionized and emit ultraviolet rays. The ultraviolet light excites red (R), green (G), and blue (B) phosphors on the surface of the discharge cell to generate visible light. Thus, an image is displayed. That is, the address electrodes A1 to Am, the scan electrodes Y1 to Yn, and the sustain electrode X correspond to the electrodes of the plasma display panel.

  The microprocessor 3 performs overall control of the plasma display device 1 and generates and outputs control signals to the sustain (maintenance) pulse control circuit 4 and the address / scan control circuit 7 particularly during video display.

  The sustain pulse control circuit 4 is a sustain pulse Y drive circuit 5 that is a circuit for sustain discharge driving (sustain driving) the scan electrodes Y1 to Yn and the sustain electrode X of the plasma display panel 2. A control signal to the sustain (sustain) pulse X driving circuit 6 is generated and output.

  The sustain pulse Y drive circuit 5 generates a voltage and a waveform for sustain driving the scan electrodes Y1 to Yn of the plasma display panel 2 and outputs them to the scan (scan) drive circuit 8.

  The sustain (sustain) pulse X driving circuit 6 generates a voltage and a waveform for sustain driving with respect to the sustain electrode X of the plasma display panel 2 and directly outputs the voltage and waveform to the sustain electrode X.

  The address / scan control circuit 7 is connected to the scan control circuit 8 and the address in the reset period, address period, and sustain period based on control signals such as a vertical synchronization signal, horizontal synchronization signal, and clock signal from the microprocessor 3. A control signal for controlling the operation timing and synchronization of the (data) drive circuit 9 is generated and output to the scan (scan) drive circuit 8 and the address (data) control circuit 9.

  The scan drive circuit 8 outputs the drive waveform input from the sustain pulse Y drive circuit 5 to the scan electrodes Y 1 to Yn based on the control signal from the address / scan control circuit 7.

  The address (data) drive circuit 9 generates and outputs a drive waveform of a predetermined voltage to the address electrodes A1 to Am based on a control signal from the address / scan control circuit 7.

  Next, a circuit diagram of a sustain pulse X driving circuit 6 as a driving device according to an embodiment of the present invention will be described with reference to FIG.

  The sustain pulse X drive circuit 6 includes transistors Tr1, Tr2, Tr3, Tr4, Tr5, Tr6, Tr7, Tr8, Tr9, Tr10, resistors R1, R2, R3, R4, diodes D1, D2, and an inductor. L1, L2, a capacitor C1, and a control circuit 63 are provided.

  Transistors Tr1, Tr2, Tr3, Tr4, Tr5, Tr6, Tr7, Tr8, Tr9, Tr10 as switching elements are composed of FETs (field effect transistors), and diodes of opposite polarity are connected in parallel between the source and drain. It is formed to be.

  In the transistor Tr1, the voltage Vs is applied to the drain, and the sustain electrode X is connected to the source. In the transistor Tr2, the sustain electrode X is connected to the drain, and the source is grounded to the ground level.

  In the transistor Tr3, a voltage VX1 as a voltage closer to the ground level than a predetermined voltage is applied to the source, and one end of the resistor R1 is connected to the drain. The resistor R1 as current suppressing means has one end connected to the drain of the transistor Tr3 and the other end connected to the drain of the transistor Tr4. The transistor Tr4 has a drain connected to the other end of the resistor R1, and a source connected to the sustain electrode X. That is, the current suppressing means is connected in series to the switching element, and a plurality of switching elements are connected in series.

  The source of the transistor Tr5 is grounded to the ground level, and one end of the resistor R2 is connected to the drain. The resistor R2 has one end connected to the drain of the transistor Tr5 and the other end connected to the sustain electrode X.

  In the transistor Tr6, a voltage VX2 as a voltage closer to the ground level than a predetermined voltage is applied to the source, and one end of the resistor R3 is connected to the drain. The resistor R3 as the current suppressing means has one end connected to the drain of the transistor Tr6 and the other end connected to the drain of the transistor Tr7. In the transistor Tr7, the other end of the resistor R3 is connected to the drain, and the sustain electrode X is connected to the source. That is, the current suppressing means is connected in series to the switching element, and a plurality of switching elements are connected in series.

  In the transistor Tr8, the sustain electrode X is connected to the source, and one end of the resistor R4 is connected to the drain. One end of the resistor R4 is connected to the drain of the transistor Tr8, and the other end is applied with a voltage Vs as a predetermined voltage.

  The transistor Tr9 has a drain grounded to the ground level together with a source of the transistor Tr10, and a source connected to the anode of the diode D1. The source of the transistor Tr10 is grounded together with the drain of the transistor Tr9 to the ground level, and the drain is connected to the cathode of the diode D2. The diode D1 has an anode connected to the source of the transistor Tr9 and a cathode connected to one end of the inductor L1. The diode D2 has an anode connected to one end of the inductor L2, and a cathode connected to the drain of the transistor Tr10. One end of the inductor L1 is connected to the cathode of the diode D1, and the other end is connected to one end of the capacitor C1 together with the other end of the inductor L2. The inductor L2 has one end connected to the anode of the diode D2 and the other end connected to one end of the capacitor C1 together with the other end of the inductor L1. Capacitor C1 has one end connected to the other ends of inductors L1 and L2, and the other end connected to sustain electrode X.

  The control circuit 63 as the control means performs ON / OFF control (gate control) of the transistors in order with the transistors predetermined for each subfield based on the control signal input from the sustain pulse control circuit 4. ing.

  Here, the voltages VX1 and VX2 are set to voltages closer to the ground level than the voltage Vs applied to the sustain electrode X by the resistor R4 and the transistor Tr8. Further, the voltage VX1 and the voltage VX2 are different voltages, and the voltage VX2 is set to a voltage closer to the ground level than the voltage VX1.

  The transistors Tr1 and Tr2 give the sustain electrode X with a pulse waveform for performing the sustain operation in the sustain period. That is, the voltage Vs and the ground level are alternately applied to the sustain electrode X.

  The resistor R4 and the transistor Tr8 apply the voltage Vs to the sustain electrode X in the reset period.

  The transistor Tr3, the resistor R1, and the transistor Tr4 apply the voltage VX1 during the reset period. That is, the circuit 61 including the transistor Tr3, the resistor R1, and the transistor Tr4 corresponds to the voltage applying unit in the claims.

  The transistor Tr6, the resistor R3, and the transistor Tr7 apply the voltage VX2 during the reset period. That is, the circuit 62 including the transistor Tr6, the resistor R3, and the transistor Tr7 corresponds to the voltage applying unit in the claims.

  The resistor R2 and the transistor Tr5 are set to the ground level after Vs, VX1, or VX2 is applied in the reset period.

  Transistors Tr9 and Tr10, diodes D1 and D2, inductors L1 and L2, and capacitor C1 form a power recovery circuit in the sustain period.

  Next, the operation in the reset period of the sustain pulse X driving circuit 6 having the above-described configuration will be described with reference to FIG. FIG. 4 shows an example of drive waveforms applied to the scan electrodes Y1 to Yn, the sustain electrode X, and the address electrodes A1 to Am during the reset period of the sustain pulse X drive circuit 6.

  The waveform shown in FIG. 4 is a waveform in the reset period of subfields 0 to 2. Unlike the plasma display panel described in the prior art, this embodiment does not repeat the reset period, address period, and sustain period in each subfield, but provides a reset period at the beginning of one field, and then the address period and sustain period. This is a plasma display panel that repeats the above. This method has an advantage that the dark portion contrast can be increased as compared with the conventional method. However, the present invention is not limited to this method and can be applied to a conventional method. In FIG. 4, the reset period is a predetermined period at the beginning of one field, and each subfield period is a predetermined period obtained by equally dividing the reset period by the number of subfields, for example. In the following description, the drive waveform of the sustain electrode X to which the present invention is applied will be described.

  First, in subfield 0, the transistor Tr8 is turned on and the voltage Vs is applied to the sustain electrode X. Then, the potential of the sustain electrode X rises from the ground level (GND level) to Vs. Then, the transistor Tr8 is turned off and the transistor Tr5 is turned on to lower the potential of the sustain electrode X to the ground level.

  Next, in the subfield 1, the transistor Tr8 is turned on, Vs is applied to the sustain electrode X, and the potential of the sustain electrode X is raised from the ground level to Vs. Then, the transistor Tr8 is turned off and the transistors Tr3 and Tr4 are turned on to lower the potential of the sustain electrode X to VX1, which is a potential closer to the ground level than Vs. Then, the transistors Tr3 and Tr4 are turned off and the transistors Tr6 and Tr7 are turned on to lower the sustain electrode X to VX2, which is a potential closer to the ground level than the potential VX1. Then, the transistors Tr6 and Tr7 are turned off and the transistor Tr5 is turned on to lower the potential of the sustain electrode X to the ground level. That is, the peak current is dispersed by gradually lowering the potential of the sustain electrode X from Vs to the ground level at once, not via VX1 and VX2. That is, with respect to a plurality of voltage applying means, the voltage applying means for applying a voltage having a potential close to a predetermined voltage is switched to a voltage applying means for gradually applying a voltage having a potential close to the ground level.

  In subfield 2, sustain electrode X remains at the ground level, but this is due to the specifications of the plasma display panel used in the example, so when another plasma display panel is used, the drive is adapted to that specification. A waveform may be applied.

  According to this embodiment, the sustain pulse X driving circuit 6 is applied with the voltage 61 having a potential closer to the ground level than the voltage Vs applied during the reset period, and closer to the ground level than the voltage VX1. A circuit 62 for applying the voltage VX2 is provided, and the voltage VX1 and the voltage VX2 are gradually decreased from the voltage Vs to the ground level, so that the peak current flowing through the circuit can be dispersed and steep Since current can be prevented from flowing, noise can be reduced. In addition, since the current is reduced, the rating of the transistor to be used and the resistance can be lowered, so that the cost can be reduced.

  In addition, since the transistors are connected in series in the circuits 61 and 62, current due to a diode formed in the transistors can be suppressed.

  Further, by combining the voltages Vs, VX1, and VX2, it becomes easy to generate a waveform required by the specifications of the plasma display panel.

  The waveform shown in FIG. 4 is arbitrarily determined depending on the characteristics of the plasma display panel, and is not limited to FIG.

  Further, the voltages VX1 and VX2 are not limited to two and may be one or three or more. Of course, in that case, it is necessary to connect the circuit corresponding to the circuits 61 and 62 to the sustain electrode X accordingly.

  In the above-described embodiments, the sustain (sustain) pulse X drive circuit 6 has been described. However, the sustain (sustain) pulse Y drive circuit 5 and the address (data) drive circuit 9 can be similarly applied.

  Further, although applied in the reset period in the above-described embodiments, it can be similarly applied to waveforms applied in the address period and the sustain period.

  In the above-described embodiments, FETs are used as switching elements, but bipolar transistors may be used.

  According to the embodiment described above, the following sustain pulse X driving circuit 6 can be obtained.

(Supplementary Note 1) In the sustain pulse X driving circuit 6 for applying the voltage Vs to the sustain electrode X of the plasma display panel 2 in order to cause the display element of the plasma display panel 2 to discharge,
A sustain pulse X drive circuit 6 comprising a circuit 61 for applying a voltage VX1 having a potential closer to the ground level than the voltage Vs to the sustain electrode X.

  According to the sustain pulse X driving circuit 6, when the potential is lowered from the voltage Vs to the ground level, the voltage VX1 having a potential closer to the ground level than the voltage Vs is set to the ground level and then the peak is obtained. Since the current can be dispersed, it is possible to prevent a steep current from flowing through the sustain (sustain) pulse X driving circuit 6, thereby reducing noise. Further, since the current is reduced, the rating of the element used for the sustaining (sustain) pulse X driving circuit 6 can be lowered, so that the cost can be reduced.

  In addition, the Example mentioned above only showed the typical form of this invention, and this invention is not limited to an Example. That is, various modifications can be made without departing from the scope of the present invention.

It is explanatory drawing of the plasma display panel in a prior art. 1 is a block diagram of a plasma display apparatus according to an embodiment of the present invention. FIG. 2 is a circuit diagram of a sustain pulse X driving circuit of the plasma display device shown in FIG. 1. FIG. 3 is a waveform diagram showing a drive waveform in a reset period of the sustain pulse X drive circuit shown in FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma display apparatus 2 Plasma display panel 6 Sustain (sustain) pulse X drive circuit (drive apparatus)
61 circuit (voltage application means)
62 circuit (voltage application means)
63 Control circuit (control means)
X Sustain electrode (electrode)
Tr3 transistor (switching element)
Tr4 transistor (switching element)
Tr6 transistor (switching element)
Tr7 transistor (switching element)
R1 resistance (current suppression means)
R3 resistance (current suppression means)
Vs voltage (predetermined voltage)
VX1 voltage (voltage with potential close to ground level)
VX2 voltage (voltage with potential close to ground level)

Claims (7)

In the driving device for applying a predetermined voltage to the electrodes of the plasma display panel in order to cause discharge in the display element of the plasma display panel,
A driving apparatus comprising voltage applying means for applying a voltage having a potential closer to a ground level than the predetermined voltage to the electrode.   The driving apparatus according to claim 1, wherein the voltage applying unit is configured by a switching element.   The drive device according to claim 1, wherein a plurality of the switching elements of the voltage application unit are connected in series.   4. The voltage application unit includes a current suppression unit configured to suppress a current flowing through the voltage application unit in series with the switching element. 5. The drive device described.   5. The driving apparatus according to claim 1, wherein a plurality of the voltage applying units are provided, and the plurality of voltage applying units apply different voltages to each other.   Control means for switching from the voltage applying means for applying a voltage having a potential close to the predetermined voltage to the voltage applying means for gradually applying a voltage having a potential close to the ground level is provided for the plurality of voltage applying means. The driving device according to claim 1, wherein the driving device is characterized in that:   A plasma display device comprising the driving device according to claim 1.

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