Method of driving a light source, light source apparatus for performing the method, and display apparatus having the light source apparatus
View Patent ↗A method of driving a light source, a light source apparatus for performing the method, and a display apparatus having the light source apparatus are disclosed in accordance with one or more embodiments. In the method, a plurality of light source strings connected in parallel is driven by applying a driving voltage to a first terminal of the light source strings. A peak current due to a voltage deviation of each of the light source strings is switch-controlled to uniform an average current of the light source strings. Thus, a peak current flowing through light source strings in accordance with a voltage deviation of the light source strings is switch-controlled, so that an average current of the light source strings may be uniformly maintained. Therefore, a voltage deviation is not consumed as power, so that damage to circuit elements due to heat may be prevented.
1. A method of driving a light source having a plurality of light source strings, the method comprising:
driving the plurality of light source strings with a driving voltage applied to a common first terminal of the light source strings; and
for each respective light source string, determining an over-time integral of current passed through the respective light source string and based on the determined integral, switch-controlling wise limiting a duration of when peak current passes through the respective light source string so as to thereby maintain a predetermined average current in each respective one of the light source strings.
2. The method of claim 1 , wherein the maintaining of the predetermined average current in each respective one of the light source strings is carried out in synchronization with a respective one of a plurality of dimming signals respectively provided for controlling a luminance of each respective one of the light source strings.
3. The method of claim 2 , wherein for each respective light source string, the corresponding switch-controlling wise limiting of the duration of when peak current passes through has a frequency that is greater than a maximum switching frequency used for the respective one of the dimming signals.
4. A light source apparatus comprising:
a light source module comprising a plurality of light source strings that are connected to receive a driving voltage through a common first terminal thereof; and
a multi-channel current control part having a plurality of control lines respectively connected to respective second terminals of each of the light source strings, the multi-channel current control part including a plurality of current control circuits adapted to switch-control wise limit respective durations of when respective peak currents pass through the respective light source strings so as to thereby maintain a predetermined average current in each respective one of the light source strings.
5. The light source apparatus of claim 4 , wherein:
each of the current control circuits is adapted to limit a flowing time of the respective peak current of the light string in response to an over-time integral of the respective peak current of the respective light source string rising to hit a predetermined limit level.
6. The light source apparatus of claim 5 , wherein each of the current control circuits comprises:
a filter connected to the respective second terminal of the respective one of the light source strings, the filter adapted to determine an over-time integral of the respective peak current flowing through the respective light source string so as to output a comparison signal by which duration of the peak flow is determined;
a control transistor comprising an input electrode connected to the second terminal of the respective light source string and an output electrode connected to the filter; and
a comparator adapted to output an output signal to a control electrode of the control transistor, the output signal controlling a turn-on or a turn-off of the control transistor in accordance with a comparison result of a reference signal and the comparison signal.
7. The light source apparatus of claim 6 , wherein the current control circuit further comprises an input part connected to an output terminal of the comparator and a control electrode of the control transistor to receive a dimming signal controlling a luminance of the light source string.
8. The light source apparatus of claim 7 , wherein for each respective light source string, the corresponding switch-controlling wise limiting of the duration of when peak current passes through has a frequency greater than a maximum switching frequency used for the respective one of the dimming signals.
9. The light source apparatus of claim 7 , further comprising:
a multi-channel voltage detecting part connected to the second terminals of the light source strings to detect a detection voltage from the light source strings; and
a light source driving part adapted to control a generation of the driving voltage in accordance with the detection voltage.
10. The light source apparatus of claim 9 , wherein:
the multi-channel voltage detecting part comprises a plurality of detection circuits connected to second terminals of the light source strings, and wherein:
each of the detection circuits comprises:
a resistor connected to a second terminal of each of the light source strings;
a diode connected to the resistor; and
an input part connected to the resistor and the diode to receive the dimming signal.
11. A display apparatus comprising:
a display panel adapted to display an image;
a light source module comprising a plurality of light source strings that are connected to receive a driving voltage through a common first terminal thereof; and
a multi-channel current control part having a plurality of control lines respectively connected to respective second terminals of each of the light source strings, wherein the multi-channel current control part includes a plurality of current control circuits adapted to switch-control wise limit respective durations of when respective peak currents pass through the respective light source strings so as to thereby maintain a predetermined average current in each respective one of the light source strings.
12. The display apparatus of claim 11 , wherein the multi-channel current control part comprises a plurality of current control circuits and each current control circuit comprises:
a filter connected to a second terminal of a first one of the light source strings, the filter adapted to determine a frequency of the peak current flowing through the first light source string to output a comparison signal by which the frequency is determined;
a control transistor comprising an input electrode connected to the second terminal of the first light source string and an output electrode connected to the filter; and
a comparator adapted to output an output signal to a control electrode of the control transistor, the output signal controlling a turn-on or a turn-off of the control transistor in accordance with a comparison result of a reference signal and the comparison signal.
13. The display apparatus of claim 12 , wherein the current control circuit further comprises an input part connected to an output terminal of the comparator and a control electrode of the control transistor to receive a dimming signal controlling a luminance of the light source string.
14. The display apparatus of claim 13 , wherein for each respective light source string, the corresponding switch-controlling wise limiting of the duration of when peak current passes through has a frequency greater than a maximum switching frequency used for the respective one of the dimming signals.
15. The display apparatus of claim 13 , further comprising:
a multi-channel voltage detecting part connected to the second terminals of the light source strings to detect a detection voltage from the light source strings; and
a light source driving part adapted to control a generation of the driving voltage in accordance with the detection voltage.
16. The display apparatus of claim 15 , wherein:
the multi-channel voltage detecting part comprises a plurality of detection circuits connected to second terminals of the light source strings, and wherein:
each of the detection circuits comprises:
a resistor connected to a second terminal of each of the light source strings;
a diode connected to the resistor; and
an input part connected to the resistor and the diode to receive the dimming signal.
17. A light source apparatus comprising:
a light source module comprising a plurality of light source strings that are connected in parallel, the light source strings adapted to receive a driving voltage through a first terminal thereof; and
a multi-channel current control part connected to a second terminal of each of the light source strings, the multi-channel current control part adapted to switch-control a peak current due to a voltage deviation of the light source strings to uniformly maintain an average current of the light source strings,
wherein:
the multi-channel current control part comprises a plurality of current control circuits connected to the light source strings, and
each of the current control circuits comprises:
a filter connected to a second terminal of a first one of the light source strings, the filter adapted to determine a frequency of the peak current flowing through the first light source string to output a comparison signal by which the frequency is determined;
a control transistor comprising an input electrode connected to the second terminal of the first light source string and an output electrode connected to the filter; and
a comparator adapted to output an output signal to a control electrode of the control transistor, the output signal controlling a turn-on or a turn-off of the control transistor in accordance with a comparison result of a reference signal and the comparison signal.
18. A display apparatus comprising:
a display panel adapted to display an image;
a light source module comprising a plurality of light source strings that are connected in parallel, the light source strings adapted to receive a driving voltage through a first terminal thereof; and
a multi-channel current control part connected to a second terminal of each of the light source strings and adapted to uniformly maintain an average current of each of the light source strings by switch-controlling a peak current due to a voltage deviation of the light source strings,
wherein:
the multi-channel current control part comprises a plurality of current control circuits connected to the light source strings, and
each of the current control circuits comprises:
a filter connected to a second terminal of a first one of the light source strings, the filter adapted to determine a frequency of the peak current flowing through the first light source string to output a comparison signal by which the frequency is determined;
a control transistor comprising an input electrode connected to the second terminal of the first light source string and an output electrode connected to the filter; and
a comparator adapted to output an output signal to a control electrode of the control transistor, the output signal controlling a turn-on or a turn-off of the control transistor in accordance with a comparison result of a reference signal and the comparison signal.