Backlight driving circuit and display apparatus
View Patent ↗A backlight driving circuit that provides backlight to a display panel of a display apparatus includes a power supply unit configured to supply power, a converter configured to convert and output a voltage of the supplied power, a light-emitting module supplied with the outputted voltage from the converter and providing the backlight, a switch connected to an output terminal of the light-emitting module and controlling an operation of the light-emitting module, a feedback resistor connected to an output terminal of the switch and sensing a voltage of a current flowing in the light-emitting module, a short-circuit sensing resistor connected between a ground of the power supply unit and a ground of the feedback resistor, and a short-circuit sensor configured to sense a voltage value of a current applied to the feedback resistor or the short-circuit sensing resistor according to whether the switch is switched on or off.
1. A backlight driving circuit that provides backlight to a display panel of a display apparatus, the backlight driving circuit comprising:
a power supply unit configured to supply power;
a converter configured to:
convert a voltage of the supplied power; and
output the converted voltage;
a light-emitting module supplied with the outputted voltage from the converter, the light-emitting module being configured to provide the backlight;
a switch connected to an output terminal of the light-emitting module, the switch being configured to control an operation of the light-emitting module;
a feedback resistor connected to an output terminal of the switch, the feedback resistor being configured to sense a voltage of a current flowing in the light-emitting module;
a short-circuit sensing resistor connected between a ground of the power supply unit and a ground of the feedback resistor; and
a short-circuit sensor configured to sense a voltage value of a current applied to the feedback resistor or the short-circuit sensing resistor according to whether the switch is switched on or off, thereby determining whether the backlight driving circuit is short-circuited.
2. The backlight driving circuit as claimed in claim 1 , wherein the short-circuit sensor is further configured to sense the voltage value of the current applied to the short-circuit sensing resistor to determine whether the backlight driving circuit is short-circuited if the switch is switched off.
3. The backlight driving circuit as claimed in claim 2 , wherein the short-circuit sensor is further configured to determine that the backlight driving circuit is short-circuited if:
the switch is switched off; and
the voltage value of the current applied to the short-circuit sensing resistor and sensed by the short-circuit sensor is less than a particular value.
4. The backlight driving circuit as claimed in claim 3 , wherein the short-circuit sensor is further configured to determine that the backlight driving circuit is short-circuited if:
the switch is switched off; and
the voltage value of the current applied to the short-circuit sensing resistor and sensed by the short-circuit sensor is:
less than the particular value; and
sensed for a preset time.
5. The backlight driving circuit as claimed in claim 4 , wherein the preset time is 80 msec.
6. The backlight driving circuit as claimed in claim 1 , wherein the short-circuit sensor is further configured to sense the voltage value of the current applied to the feedback resistor to determine whether the backlight driving circuit is short-circuited if the switch is switched on.
7. The backlight driving circuit as claimed in claim 6 , wherein the short-circuit sensor is further configured to determine that the backlight driving circuit is short-circuited if:
the switch is switched on; and
the voltage value of the current applied to the feedback resistor and sensed by the short-circuit sensor is less than a particular value.
8. The backlight driving circuit as claimed in claim 7 , wherein the short-circuit sensor is further configured to determine that the backlight driving circuit is short-circuited if:
the switch is switched on; and
the voltage value of the current applied to the feedback resistor and sensed by the short-circuit sensor is:
less than the particular value; and
sensed for a preset time.
9. The backlight driving circuit as claimed in claim 8 , wherein the short-circuit sensor is further configured to determine whether the voltage value of the current applied to the feedback resistor and sensed by the short-circuit sensor is less than the particular value only if:
the preset time is greater than a time for which the switch is switched on; and
the switch is switched on when the switch is repeatedly switched on and off.
10. The backlight driving circuit as claimed in claim 8 , wherein the preset time is 80 msec.
11. The backlight driving circuit as claimed in claim 1 , wherein the short-circuit sensor comprises:
a first comparator configured to compare the voltage value of the current applied to the feedback resistor with a first reference voltage value;
a second comparator configured to compare the voltage value of the current applied to the short-circuit sensing resistor with a second reference voltage value;
a mode selector configured to:
select a mode according to whether the switch is switched on or off; and
output a comparison result of one of the first and the second comparators according to the selected mode;
a timing counter configured to determine whether the comparison result output from the mode selector is maintained for a preset time; and
a signal generator configured to:
sense whether the backlight driving circuit is short-circuited by using the comparison result of the one of the first and second comparators output from the mode selector selected according to whether the switch is switched on or off; and
generate a short-circuit sensing signal configured to protect a device of the backlight driving circuit if it is sensed that the backlight driving circuit is short-circuited.
12. The backlight driving circuit as claimed in claim 1 , wherein the short-circuit sensing resistor senses whether the backlight driving circuit is short-circuited in response to the switch being turned off.
13. The backlight driving circuit as claimed in claim 1 , wherein the feedback resistor senses whether the backlight driving circuit is short-circuited in response to the switch being turn on.
14. A display apparatus, comprising:
an image processor configured to process a signal of an input image;
a display panel configured to display the image having the processed signal; and
a backlight driving circuit configured to provide backlight to the display panel, the backlight driving circuit comprising:
a power supply unit configured to supply power;
a converter configured to:
convert a voltage of the supplied power; and
output the converted voltage;
a light-emitting module supplied with the outputted voltage from the converter, the light-emitting module being configured to provide the backlight;
a switch connected to an output terminal of the light-emitting module, the switch being configured to control an operation of the light-emitting module;
a feedback resistor connected to an output terminal of the switch, the feedback resistor being configured to sense a voltage of a current flowing in the light-emitting module;
a short-circuit sensing resistor connected between a ground of the power supply unit and a ground of the feedback resistor; and
a short-circuit sensor configured to sense a voltage value of a current applied to the feedback resistor or the short-circuit sensing resistor according to whether the switch is switched on or off, thereby determining whether the backlight driving circuit is short-circuited.