This application claims priority to Korean Patent Application No. 2002-18018, filed Apr. 2, 2002, which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an apparatus and method for controlling a power supply of a display panel driving system, and more particularly, to an apparatus and method for controlling automatic adjustment of a power supply of a display panel driving system, by automatically adjusting a voltage of the power supply of the display panel driving system to have an optimal image quality based on a sensed image state.
2. Description of the Related Art
As shown in FIG. 1, a related art general plasma display panel driving system includes a scan electrode driving board 110, a plasma display panel (PDP) 120, a common electrode driving board 130 and an address driver integrated circuit (IC) 140.
A driving sequence of the related art PDP 120 is divided into a reset period, a scan period and a sustain period, which are repeated. In the reset period, a display hysteresis is removed by discharging all cells and simultaneously eliminating wall charges. In the scan period, the cells are selected by matrix configuration due to a combination of raw electrodes and column electrodes so that an address discharge is formed. In the sustain period, an image is displayed while repeatedly charging and discharging the cells, which are selected in the scan period, using an energy recovery process.
A driving sequence comprised of respective operation periods of a PDP driving system is disclosed in, U.S. Pat. No. 4,866,349.
As shown in FIG. 2, stable direct current (DC) voltages such as a sustain circuit driving voltage Vs (160-190V DC), a reset circuit driving voltage Vset (200-230V DC) of the scan electrode driving board 110, a bias circuit driving voltage Ve (180-200V DC) of the common electrode driving board 130, a scan circuit voltage Vscan (60-80V DC) and an address circuit voltage Va (60-80V DC) are supplied to the PDP driving system by a general panel power supply circuit including a rectifying circuit 210 and a plurality of DC/DC converters 220-1 to 220-6, so that the above-described driving sequence comprised of the respective operation periods of the PDP driving system is performed.
Changes in the voltages supplied to the PDP driving system directly affect the contrast and brightness of an image, and thus the voltages must be controlled in consideration of a deviation of the panel performance.
According to the prior art, as shown in FIG. 3, supply voltage is manually adjusted by a control circuit for voltage adjustment including a general flyback DC/DC converter circuit. Since an output voltage Vs,sense which is sensed at a point connecting a resistor R2 and a variable resistor VR1 though feedback control, follows a reference voltage Vref of an error amplifier 30-2, the voltage Vs,sense satisfies Equation 1:                                           V                          s              ,              sense                                =                                                                      R                  2                                                                      R                    1                                    +                                      R                    2                                                              ⁢                              V                s                                      ≈                          V              ref                                      ⁢                  
                ⁢                              V            2                    =                                    (                              1                +                                                      R                    1                                                        R                    2                                                              )                        ⁢                          V              ref                                                          (        1        )            
In Equation 1, R1 is a resistance value of the variable resistor VR1. It can be seen from Equation 1 that a driving voltage Vs of the panel varies according to the resistance value R1 of the variable resistor VR1.
Conventionally, the various driving voltages, for example, Vs, Vset, Va and Ve, in a PDP set manufacturing process are manually adjusted using the variable resistor in the circuit as shown in FIG. 3, so that an image is adjusted to have the best possible image quality.
Thus, according to the prior art, there are problems in that, for example, a manufacturing process of the PDP driving system is complex. Also, it is difficult to accurately adjust an image during mass production by manually adjusting the driving voltages required by the PDP driving system using the variable resistor.
To solve the above-described problems, it is an object of the present invention to provide an apparatus and method for controlling automatic adjustment of a power supply of a display panel driving system, in order to automatically adjust driving voltages of a display panel by sensing contrast information and brightness information, which are affected by changes in the driving power supply, and driving the plasma display panel to have the best possible image quality based on the sensed contrast information and brightness information.
According to an aspect of the present invention, an apparatus for automatically controlling automatic adjustment of a power supply of a display panel driving system comprises a look-up table which stores power supply control data for controlling a display panel driving power supply corresponding to predetermined image information; a sensor which senses the predetermined image information from an image signal output from the display panel; a control circuit which converts the image information sensed by the sensor into digital data, reads power supply control data corresponding to a value of the digital data of the image information from the look-up table, and generates a power supply control signal corresponding to the power supply control data; and a power supply adjusting circuit which automatically changes a predetermined voltage of the power supply supplied to a display panel driving circuit according to the power supply control signal.
According to another aspect of the present invention, a method for controlling a power supply of a display panel driving system comprises (a) sensing with a sensor predetermined image information from an image signal output from a display panel, (b) reading from a look-up table power supply control data corresponding to the sensed predetermined image information, (c) generating a pulse-width modified power supply control signal from the read power supply control data, and (d) controlling a display panel driving power supply according to the pulse-width modified power supply control signal.
Additionally, a computer-readable medium including a set of instructions is provided, wherein the instructions include (a) sensing with a sensor image information from an image signal output from a display panel, (b) reading from a look-up table power supply control data corresponding to the sensed image information, (c) generating a pulse-width modified power supply control signal from the read power supply control data, and (d) controlling a display panel driving power supply according to the pulse-width modified power supply control signal.