Display device and method of driving the same
A display device includes a light emitting diode array including a plurality of light emitting diodes, a monitoring circuit configured to generate a monitoring signal corresponding to a forward voltage of a first light emitting diode of the plurality of light emitting diodes, a backlight controller configured to control the amount of current flowing to the light emitting diode array, and a first luminance compensation circuit configured to increase the amount of current flowing to the light emitting diode array in response to the monitoring signal.
1. A display device comprising:
a display portion including a plurality of pixels;
a light emitting diode array including a plurality of light emitting diodes and configured to emit light toward the display portion;
a monitoring circuit configured to generate a monitoring signal corresponding to a forward voltage of a first light emitting diode of the plurality of light emitting diodes;
a backlight controller configured to control the amount of current flowing to the light emitting diode array; and
a first luminance compensation circuit configured to increase the amount of current flowing to the light emitting diode array in response to the monitoring signal,
wherein the backlight controller comprises:
a first transistor connected between the light emitting diode array and a ground;
a first amplifier including an output terminal connected to a gate electrode of the first transistor;
a second transistor including a gate electrode connected to a first node, and connected between a power voltage and the first amplifier;
a second amplifier including a first input terminal to which a backlight control signal is input; and
a third transistor including a gate electrode connected to an output terminal of the second amplifier, and connected between the first node and the ground.
2. The display device of claim 1 , wherein the first luminance compensation circuit increases the amount of current flowing to the light emitting diode array when the forward voltage of the first light emitting diode is decreased.
3. The display device of claim 1 , wherein the monitoring circuit comprises a first monitoring amplifier that includes a first input terminal connected to an anode of the first light emitting diode, a second input terminal connected to a cathode of the first light emitting diode, and an output terminal configured to output a first voltage difference between the anode and the cathode.
4. The display device of claim 3 , wherein the monitoring circuit further comprises a second monitoring amplifier that includes a first input terminal connected to a reference voltage of the first light emitting diode, a second input terminal connected to the output terminal of the first monitoring amplifier, and an output terminal configured to output a second voltage difference between the first voltage difference and the reference voltage as the monitoring signal.
5. The display device of claim 4 , wherein the reference voltage of the first light emitting diode is the forward voltage of the first light emitting diode at a predetermined reference temperature.
6. The display device of claim 1 , wherein the backlight controller further comprises a fourth transistor that includes a gate electrode connected to the first node and is connected between the power voltage and the third transistor.
7. The display device of claim 6 , wherein the first luminance compensation circuit comprises a fifth transistor that includes a gate electrode configured to receive the monitoring signal and is connected between the first node and the ground.
8. The display device of claim 7 , further comprising an analog-to-digital (A/D) converter configured to convert the monitoring signal to a digital color coordinate control signal.
9. The display device of claim 8 , further comprising a second luminance compensation circuit configured to decrease the amount of current flowing to the light emitting diode array in response to the digital color coordinate control signal.
10. The display device of claim 9 , wherein the second luminance compensation circuit comprises a variable resistor connected between the third transistor and the ground, and a resistance value of the variable resistor changes in response to the digital color coordinate control signal.
11. The display device of claim 9 , wherein the second luminance compensation circuit decreases the amount of current flowing to the light emitting diode array when the forward voltage of the first light emitting diode is increased.
12. The display device of claim 8 , further comprising:
a first lookup table that includes a plurality of first color coordinate weight values maintaining color coordinate values of red and green with a reference value and decreasing a color coordinate value of blue as a temperature of the light emitting diode array is increased from a predetermined reference temperature; and
an image data generator configured to select one of the plurality of first color coordinate weight values that corresponds to the digital color coordinate control signal from the first lookup table and to generate an image data signal using the selected one of the plurality of first color coordinate weight values.
13. The display device of claim 12 , further comprising a second lookup table that includes a plurality of second color coordinate weight values maintaining the color coordinate value of blue with the reference value and decreasing the color coordinate values of red and green as the temperature of the light emitting diode array is decreased from the predetermined reference temperature,
wherein the image data generator selects one of the plurality of second color coordinate weight values corresponding to the digital color coordinate control signal from the second lookup table and generates the image data signal using the selected one of the plurality of second color coordinate weight values.
14. A display device comprising:
a display portion including a plurality of pixels;
a backlight circuit including a plurality of light emitting diodes and configured to emit light toward the display portion;
an analog-to-digital (A/D) converter configured to provide a color coordinate control signal to the backlight circuit in response to a monitoring signal; and
a monitoring circuit configured to generate the monitoring signal corresponding to a forward voltage of one of the plurality of light emitting diodes acrd to provide the monitoring signal to the backlight circuit and the A/D converter,
wherein the backlight circuit is configured to adjust luminance of the emitted light in response to the monitoring signal and the color coordinate signal, and
wherein the monitoring circuit comprises a first monitoring amplifier that includes a first input terminal connected to an anode of the one of the plurality of light emitting diodes, a second input terminal connected to a cathode of the one of the plurality of light emitting diodes, and an output terminal configured to output a first voltage difference between the anode and the cathode.
15. The display device of claim 14 , wherein
the backlight circuit increases the luminance by increasing the amount of current flowing to the plurality of light emitting diodes when an ambient temperature of the plurality of light emitting diodes increases from a reference temperature, and
the backlight circuit decreases the luminance by reducing the amount of current flowing to the plurality of light emitting diodes when the ambient temperature decreases from the reference temperature.