This application claims the benefit of Korean Patent Application No. 10-2008-0084950 filed on Aug. 29, 2008, which is hereby incorporated by reference.
1. Field of the Disclosure
This document is directed to a plasma display apparatus.
2. Description of the Background Art
A plasma display apparatus includes a plasma display panel and a driver. The plasma display panel includes discharge cells, each of which is partitioned from the others by barrier walls. When the driver supplies a driving signal to electrodes of the plasma display panel, a discharge occurs at a discharge cell in response to the driving signal, and when the discharge excites the phosphor within the discharge cell, the phosphor emits light.
A plasma display apparatus expresses a gray level based on a combination of subfields. That is, the plasma display apparatus externally emits light during each subfield and a gray scale is represented according to a mixture of light externally emitted during each subfield.
Each subfield includes a reset period, an address period, and a sustain period. During a reset period, wall charges are uniformly created at the whole discharge cells of the display panel. A discharge cell, which will emit light, is selected during an address period. Light is emitted from the selected discharge cell during a sustain period.
Meanwhile, it becomes a critical issue to reduce costs of manufacturing the driver of flat display apparatus as its competence is overheated. Korean Patent Application Publication Nos. 2007-0106329, 2006-0121020, 2006-0121019, and 2006-0119582 disclose simplifying the circuit of driver.
The plasma display apparatus includes a plasma display panel configured to include a scan electrode, a sustain electrode, and a data electrode; and a scan driver configured to supply the scan electrode with a first driving voltage serving as a reference voltage, a second driving voltage supplied from a single voltage source, and a third driving voltage that has the same magnitude as that of the second driving voltage and has the opposite polarity of that of the second driving voltage, wherein the scan driver includes an energy recovery circuit configured to supply or recover a charged voltage, a first signal generator configured to generate the second driving voltage and a set-up signal gradually rising up to double of the second driving voltage, a second signal generator configured to generate the first driving voltage, and generate a set-down signal gradually falling to the third driving voltage and a scan signal falling to the third driving voltage, a voltage supplier configured to supply the second driving voltage, the third driving voltage, and double of the second driving voltage through the first signal generator or the second signal generator, a scan driver configured to supply a scan electrode with a driving signal generated from the energy recovery circuit, the first signal generator, and the second signal generator, and a switching unit configured to allow a voltage provided from the voltage supplier to be supplied to the first signal generator or the second signal generator.
The energy recovery circuit may supply a voltage charged to an energy storage capacitor through a first switch and an inductor, and charge the energy storage capacitor through the inductor and a second switch.
The first signal generator may include a first switch connected to a voltage source supplying the second driving voltage, wherein the first switch generates a signal sharply varying or a signal gradually varying.
The first switch may generate a signal sharply varying as being supplied with a turn-on control signal through a first input terminal and a signal gradually varying as being supplied with a turn-on control signal through a second input terminal.
A slope of the signal gradually varying may change with the magnitude of a variable resistor connected to the second input terminal.
The second signal generator may include a second switch that receives the first driving voltage and is connected to the scan driver.
The second switch may generate a signal sharply varying as being supplied with a turn-on control signal through a third input terminal and a signal gradually varying as being supplied with a turn-on control signal through a fourth input terminal.
A slope of the signal gradually varying may change with the magnitude of a variable resistor connected to the fourth input terminal.
The voltage supplier may include a capacitor that is connected to the first signal generator and the second signal generator.
The scan driver may supply the scan electrode with a driving signal generated from the energy recovery circuit, the first signal generator, and the second signal generator through a top switch or a bottom switch.
The switching unit may include a first path switch connected between the first signal generator and the voltage supplier, a second path switch connected between the second signal generator and the voltage supplier, and a third path switch connected between the voltage supplier and a common terminal of the second path switch and the second signal generator.
A voltage source supplying the second driving voltage, a first path switch of the switching unit, the voltage supplier, a third path switch of the switching unit, and a second switch of the second signal generator may be connected to each other and the second switch, the third path switch, and a bottom switch of the scan driver may be connected to each other.
A second switch of the second signal generator, a second path switch of the switching unit, the voltage supplier, and a bottom switch of the scan driver may be connected to each other.
A voltage source supplying the second driving voltage, a first switch of the first signal generator, and a bottom switch of the scan driver may be connected to each other.
A second switch of the second signal generator, a third path switch of the switching unit, and the voltage supplier may be connected to each other.
A voltage source supplying the second driving voltage, a first switch of the first signal generator, the voltage supplier, a second path switch of the switching unit, and a top switch of the scan driver may be connected to each other.
A second switch of the second signal generator, a third path switch of the switching unit, and a bottom switch of the scan driver may be connected to each other.
A second switch of the second signal generator and a top switch of the scan driver may be connected to each other.
An energy storage capacitor, a first switch, and an inductor of the energy recovery circuit, and a bottom switch of the scan driver may be connected to each other, a voltage source supplying the second driving voltage, a first switch of the first signal generator, and the bottom switch of the scan driver may be connected to each other, the bottom switch of the scan driver, and the inductor, a second switch, and the energy storage capacitor of the energy recovery circuit may be connected to each other, and a second switch of the second signal generator and a top switch of the scan driver may be connected to each other.
Hereinafter, exemplary embodiments will be described with reference to accompanying drawings. Other advantages, features, and accomplishments thereof will be apparent from the exemplary embodiments that will be detailed below with reference to accompanying drawings.
Referring to
The plasma display panel 110 includes scan electrodes Y1 to Yn and sustain electrodes Z1 to Zn that are parallel with each other, and data electrodes X1 to Xm that intersect the scan electrodes Y1 to Yn and the sustain electrodes Z1 to Zn. Discharge cells (DCs) correspond to intersections between the data electrodes X1 to Xm, and the scan electrodes Y1 to Yn and the sustain electrodes Z1 to Zn.
The scan driver 111 supplies a scan electrode with a second driving voltage Vs provided from one voltage source as a driving signal.
Referring to
The scan driver 111 supplies a scan electrode with a set-up signal that gradually rises from the first driving voltage Vref to the second driving voltage Vs and then gradually rises from the second driving voltage Vs to double of the second driving voltage 2 Vs during a reset period as shown in
The first driving voltage Vref may be a ground voltage. Wall charges are sufficiently created at the entire discharge cells of the plasma display panel 110 as the set-up signal is supplied.
The slope of the set-up signal rising form the first driving voltage Vref to the second driving voltage Vs may be different from that of the set-up signal rising from the second driving voltage Vs to double of the second driving voltage 2 Vs. Accordingly, it is possible to supply a set-up signal to fit for the features of the plasma display panel.
In particular, the slope of the set-up signal rising form the first driving voltage Vref to the second driving voltage Vs may be greater than that of the set-up signal rising from the second driving voltage Vs to double of the second driving voltage 2 Vs. A weak dark discharge occurs around the peak voltage of the set-up signal during the reset period. Accordingly, when the voltage at the scan electrode rises during a short time from the first driving voltage Vref to the second driving voltage Vs, sufficient wall charges may be created at the discharge cell, whereas when the voltage at the scan electrode rises during a relatively long time from the second driving voltage Vs to double of the second driving voltage 2 Vs, the amount of light emitted by the dark discharge may be decreased. This leads to improvement in contrast ratio.
After supply of the set-up signal, the scan driver 111 supplies a scan electrode with a set-down signal that gradually falls down to the third driving voltage −Vs having the same magnitude as that of the second driving voltage Vs. The supply of set-down signal causes the wall charges generated at the discharge cells to be partially eliminated, thus wall charges are uniformly created at the entire discharge cells.
The scan driver 111 supplies a scan electrode with a scan signal that falls from the first driving voltage Vref to the third driving voltage −Vs during an address period. That is, the first driving voltage Vref is supplied as a scan reference voltage and it is supplied the third driving voltage −Vs that has the same magnitude as that of the second driving voltage Vs and opposite polarity of that of the second driving voltage Vs as the lowest voltage of the scan signal. The data driver 113 supplies a data electrode with a data signal rising up to the data voltage Vd while the scan signal is supplied.
As the scan signal and data signal are supplied, there are selected discharge cells that will emit light during a sustain period.
The sustain driver 115 supplies a sustain electrode with a sustain bias signal rising up to the second driving voltage Vs while the set-down signal and scan signal are supplied. As the sustain bias signal is supplied, an address discharge may smoothly occur to select discharge cells.
The scan driver 111 and the sustain driver 115 alternately supply a scan electrode and a sustain electrode with a sustain signal rising from the first driving voltage Vref to the second driving voltage Vs during a sustain period. The supply of sustain signal enables light to be emitted from discharge cells selected during the address period.
The plasma display apparatus according to an exemplary embodiment may generate a driving signal with a single voltage source that supplies the second driving voltage Vs. Accordingly, the structure of plasma display apparatus may be simplified and manufacturing costs may be reduced. The single voltage source may be mounted in the plasma display apparatus, or provided outside the plasma display apparatus to supply the second driving voltage Vs.
Referring to
After supply of the set-up signal, the scan driver 111 may supply a scan electrode with a set-down signal falling down to a fourth driving voltage −Vs that is lower than the first driving voltage Vref and higher than the third driving voltage −Vs. According to supply of the set-down signal falling to the fourth driving voltage −V4 higher than the third driving voltage −Vs, the amount of wall charges created at the discharge cells, which will be eliminated, may be controlled.
The driving signal supplied during an address period and a sustain period of the second subfield SF2 is identical to the driving signal supplied during the first subfield SF1, and thus, the detailed descriptions will be omitted. Although it has been described in the exemplary embodiment that the first subfield SF1 abuts the second subfield SF2, both may be apart from each other.
The energy recovery circuit 310 supplies a voltage charged at an energy storage capacitor Cs through a first switch Q1 and an inductor L, and electrically charges the energy storage capacitor Cs through the inductor L and a second switch Q2. While the energy recovery circuit 310 supplies or recovers a charged voltage, the inductor L makes resonance with the plasma display panel Cp. A first diode D1 and a second diode D2 block a current flowing from the cathode to the anode. A third diode D3 clamps a voltage higher than the second driving voltage Vs, and a fourth diode D4 clamps a voltage lower than the first driving voltage Vref.
The first signal generator 320 supplies the second driving voltage Vs and generates a set-up signal gradually rising up to the second driving voltage Vs or double of the second driving voltage 2 Vs. The first signal generator 320 includes a first switch S1 connected to a voltage source supplying the second driving voltage Vs. The first switch S1 generates a signal sharply varying when a turn-on control signal is supplied through a first input terminal T1 and a signal gradually varying when a turn-on control signal is supplied through a second input terminal T2. The slope of the signal gradually varying changes with the magnitude of a variable resistor Rv1 connected to the second input terminal T2.
The second signal generator 330 does not only generate the first driving voltage Vref but also a set-down signal gradually falling to the third driving voltage −Vs and a scan signal falling to the third driving signal −Vs. The second signal generator 330 includes a second switch S2 that receives the first driving voltage Vref and is connected to the scan driver 350. The second switch S2 generates a signal sharply varying when a turn-on control signal is supplied through a third input terminal T3 and a signal gradually varying when a turn-on control signal is supplied through a fourth input terminal T4. The slope of the signal gradually varying changes with the magnitude of a variable resistor Rv2 connected to the fourth input terminal T4.
The voltage supplier 340 supplies the second driving voltage Vs, the third driving voltage −Vs, and double 2 Vs of the second driving voltage through the first signal generator 320 or the second signal generator 330. The voltage supplier 340 includes a capacitor C that is connected to the first signal generator 320 and the second signal generator 330.
The scan driver 350 supplies a driving signal generated from the energy recovery circuit 310, the first signal generator 320, and the second signal generator 330 to a scan electrode through a top switch St or a bottom switch Sb.
The switching unit 360 allows a voltage provided from the voltage supplier 340 to be supplied to the first signal generator 320 or the second signal generator 330. For this purpose, the switching unit 360 includes a first path switch Spath1 connected between the first signal generator 320 and the voltage supplier 340, a second path switch Spath2 connected between the second signal generator 330 and the voltage supplier 340, and a third path switch Spath3 connected between a common terminal of the second path switch Spath2 and the second signal generator 330 and the voltage supplier 340.
Hereinafter, the operation of the scan driver will be described in detail with reference to drawings.
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At this time, the slope of the set-up signal gradually rising from the first driving voltage Vref to the second driving voltage Vs and the slope gradually rising from the second driving voltage Vs to double 2 Vs of the second driving voltage Vs vary with the variable resistor Rv1. Accordingly, as the magnitude of the variable resistor is controlled, the slope of the set-up signal may be controlled correspondingly.
Referring to
When a turn-on control signal is supplied through the first input terminal T1 after supply of the set-up signal and the bottom switch Sb turns on, the voltage of scan electrode sharply falls from double 2 Vs of the second driving voltage Vs to the second driving voltage Vs.
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As described above, since the second driving voltage Vs supplied from a single voltage source may be provided as a driving signal in the exemplary embodiment, the structure of the scan driver may be simplified. A set-down pulse switch and a sustain down switch may be shared in use.
Meanwhile, the path shown in
Thereafter, the path shown in
After supply of the set-up signal during the second subfield SF2 shown in
The exemplary embodiment may reduce manufacturing costs of a plasma display apparatus by driving the plasma display apparatus through a single power source.
Embodiments of the invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
Number | Date | Country | Kind |
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10-2008-0084950 | Aug 2008 | KR | national |
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Number | Date | Country | |
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20100053037 A1 | Mar 2010 | US |