Power supply device, display device including the power supply device, and driving method using the same
The described technology relates generally to a power supply, a display device including the same, and a driving method thereof to reduce power consumption of the display device. Embodiments include a power source voltage controller sensing a panel current flowing in the display panel and controlling a feedback voltage according to the panel current and the power source voltage, and a DC-DC converter generating a power source voltage according to the feedback voltage to respectively supply it to the plurality of light emitting elements.
1. A power supply employable for supplying a power source voltage including a first power source voltage and a second power source voltage to a panel including a plurality of elements, the power supply comprising:
a power source voltage controller to generate panel current data corresponding to a total current flowing in the plurality of elements of the panel by varying the second power source voltage within a predetermined range and fixing the first power source voltage, to obtain a power source voltage-panel current characteristic curve based on the panel current data of the second power source voltage, the power source voltage-panel current characteristic curve representing a change of the total current of the second power source voltage, to determine a target voltage value based on the power source voltage-panel current characteristic curve, and to control a feedback voltage for controlling the second power source voltage to be at least substantially equal to the target voltage value; and
a DC-DC converter to generate the first and second power source voltages, to control a voltage difference between the first and second power source voltages according to the feedback voltage, and to supply the second power source voltage to the elements, wherein
an optimization of the second power source voltage is controlled by increasing or decreasing the feedback voltage according to the target voltage value determined in the power source voltage-panel current characteristic curve, wherein:
when the second power source voltage is higher than the target voltage, the total current is limited such that the panel is not able to display a full white grayscale, and
when the second power source voltage is lower than the target voltage, unnecessary power consumption is caused to generate the second power source voltage.
2. The power supply as claimed in claim 1 , wherein
the power source voltage controller includes:
a feedback controller to generate a feedback voltage control signal corresponding to the total current, and to determine the target voltage value corresponding to the second power source voltage; and
a feedback voltage controller to control the feedback voltage according to the feedback voltage control signal, wherein the DC-DC converter uses the feedback voltage control signal to control the second power source voltage to correspond to the target voltage value.
3. The power supply as claimed in claim 2 , wherein the DC-DC converter uses the feedback voltage control signal to control the second power source voltage to at least substantially equal the target voltage value.
4. The power supply as claimed in claim 2 , wherein the feedback voltage controller includes:
a first resistor including one terminal connected to the power line;
a plurality of second resistors connected in series between a second terminal of the first resistor and a terminal supplied with a reference voltage from the DC-DC converter; and
a plurality of switches respectively connected in parallel with the plurality of second resistors, the plurality of switches to perform a switching operation according to the corresponding feedback voltage control signal among a plurality of feedback voltage control signals.
5. The power supply as claimed in claim 4 , wherein the feedback voltage is determined according to a resistance ratio between the plurality of second resistors and the first resistor.
6. The power supply as claimed in claim 1 , wherein the panel is a display panel and the plurality of elements include a plurality of light emitting elements, and wherein the DC-DC converter is to supply the second power source voltage to the light emitting elements.
7. The power supply as claimed in claim 6 , wherein
the DC-DC converter is to supply the second power source voltage to a cathode of each of the plurality of light emitting elements through a power line, and
the total current flows in the power line that includes a sensing resistor.
8. The power supply as claimed in claim 7 , wherein
the power source voltage controller further includes an amplifier to amplify a voltage difference between two terminals of the sensing resistor and to output an amplification voltage.
9. The power supply as claimed in claim 8 , wherein the power source voltage controller further includes an analog-digital converter to output the panel current data corresponding to the total current according to the amplification voltage.
10. The power supply as claimed in claim 1 , wherein the power source voltage controller includes:
a feedback controller to generate a feedback voltage control signal corresponding to the total current, to determine the target voltage value corresponding to the second power source voltage, and to generate a reference voltage data;
a digital-analog converter to generate a reference voltage according to the reference voltage data; and
a feedback voltage generator to distribute a voltage difference between the second power source voltage and the reference voltage into resistors to generate the feedback voltage, wherein the DC-DC converter uses the feedback voltage to control the second power source voltage to at least substantially equal the target voltage value.
11. The power supply as claimed in claim 10 , wherein the power source voltage controller further includes a buffer to receive the reference voltage from the digital-analog converter and to output the reference voltage.
12. The power supply as claimed in claim 11 , wherein the feedback voltage generator includes:
a first resistor having a first terminal connected to a power line supplied with the second power source voltage from the DC-DC converter;
a second resistor having a first terminal connected to a second terminal of the first resistor, and a second terminal connected to an output terminal of the buffer; and
a capacitor having a first terminal connected to the output terminal of the buffer, and a second terminal that is grounded.
13. A display device, comprising:
a display panel including a plurality of light emitting elements, and supplied with a power source voltage including a first power source voltage and a second power source voltage;
a power source voltage controller to generate panel current data corresponding to a total current flowing in the light emitting elements of the panel by varying the second power source voltage within a predetermined range and fixing the first power source voltage, to obtain a power source voltage-panel current characteristic curve based on the panel current data of the second power source voltage, the power source voltage-panel current characteristic curve representing a change of the total current of the second power source voltage, to determine a target voltage value based on the power source voltage-panel current characteristic curve, and to control a feedback voltage for controlling the second power source voltage to be at least substantially equal to the target voltage value; and
a DC-DC converter to generate the first and second power source voltages, to control a voltage difference between the first and second power source voltages according to the feedback voltage, and to respectively supply the second power source voltage to the plurality of light emitting elements, wherein an optimization of the second power source voltage is controlled by increasing or decreasing the feedback voltage according to the target voltage value determined in the power source voltage-panel current characteristic curve, wherein:
when the second power source voltage is higher than the target voltage, the total current is limited such that the panel is not able to display a full white grayscale, and
when the second power source voltage is lower than the target voltage, unnecessary power consumption is caused to generate the second power source voltage.
14. The display device as claimed in claim 13 , wherein
the power source voltage controller is further to generate control signals based on the panel current data and the second power source voltage for controlling the feedback voltage, and
the DC-DC converter is further to generate the second power source voltage to be at least substantially equal to the target voltage value based on the generated control signals.
15. A method for driving a display device, the method comprising:
generating panel current data corresponding to a total current flowing in a plurality of light emitting elements included in a panel of the display device by varying a power source voltage, the power source voltage including a first power source voltage and a second power source voltage;
determining a target voltage value for the plurality of light emitting elements by using a power source voltage-panel current characteristic curve based on the panel current data of the second power source voltage, the power source voltage-panel current characteristic curve representing a change of the total current of the second power source voltage, the change being determined by varying the second power source voltage within a predetermined range and fixing the first power source voltage; and
adjusting the second power source voltage by controlling a feedback voltage according to the target voltage value determined in the power source voltage-panel current characteristic curve, wherein:
when the second power source voltage is higher than the target voltage, the total current is limited such that the panel is not able to display a full white grayscale, and
when the second power source voltage is lower than the target voltage, unnecessary power consumption is caused to generate the second power source voltage.
16. The method as claimed in claim 15 ,
wherein controlling the feedback voltage includes:
determining the panel current data corresponding to the total current and the target voltage value corresponding to the second power source voltage,
generating at least one of reference voltage data and a plurality of feedback voltage control signals for controlling the feedback voltage, and
controlling the feedback voltage according to the reference voltage data and/or the plurality of feedback voltage control signals; and
generating the second power source voltage by using the reference voltage data and/or the feedback voltage control signals to control the second power source voltage to at least substantially equal the target voltage value.
17. The method as claimed in claim 16 , wherein controlling the feedback voltage includes distributing the second power source voltage and a predetermined reference voltage according to a resistance ratio between a first resistor and a plurality of second resistors into a voltage, and selectively connecting the plurality of second resistors according to the plurality of feedback voltage control signals to control the resistance ratio.
18. The method as claimed in claim 15 , wherein controlling the feedback voltage includes:
determining data corresponding to the total current and the target voltage value corresponding to the second power source voltage, and
generating control signals based on the panel current data and the second power source voltage for controlling the feedback voltage; and
generating the second power source voltage based on the generated control signals to be at least substantially equal to the target voltage value.