LED boost converter and backlight LED driver device using the same
View Patent ↗The present disclosure discloses an LED boost converter and an LED backlight driver using the same. The LED boost converter comprises an inductive boost circuit used in different display modes for boosting an input voltage to a working voltage necessary for the operation of LED in a current display mode; a detecting circuit used in different display modes for selecting different detecting resistors for the different display modes so as to provide different detecting currents in the inductive boost circuit; and a controller used for providing a pulse width modulation signal so as to drive the inductive boost circuit, and for detecting whether a detecting voltage corresponding to the detecting current exceeds a reference voltage. The present disclosure can avoid possible element failure or abnormal protection in the 3D display mode by arranging a detecting circuit in the LED boost converter so as to offer detecting resistors corresponding to the working currents of the 2D display mode and the 3D display mode respectively.
1. An LED boost converter, comprising:
an inductive boost circuit used in different display modes for boosting an input voltage to a working voltage necessary for the operation of an LED in a current display mode;
a detecting circuit, connected to the inductive boost circuit and used in different display modes for selecting different detecting resistors for the different display modes so as to provide different detecting currents in the inductive boost circuit; and
a controller used for providing a pulse width modulation signal so as to drive the inductive boost circuit, and for detecting whether a detecting voltage corresponding to the detecting current exceeds a reference voltage, the controller including a GATE end connected to the inductive boost circuit and a current detection input end connected to the detecting circuit; and
wherein the display modes comprise a 2D display mode and a 3D display mode, and
wherein when an inductive peak current I pk _ 2D of the 2D display mode inductive boost circuit is smaller than an inductive peak current I pk _ 3D of the 3D display mode inductive boost circuit, the detecting circuit further includes:
a first resistor, with one end thereof connected to a ground, and the other end thereof connected to a source of a switching transistor of the inductive boost circuit;
a second resistor, with one end thereof connected to the source of the switching transistor together with the first resistor; and
a first switching transistor, with a grid thereof connected to a 2D/3D switching signal input end, a drain thereof connected to the other end of the second resistor, and a source thereof connected to the ground.
2. An LED boost converter, comprising:
an inductive boost circuit used in different display modes for boosting an input voltage to a working voltage necessary for the operation of an LED in a current display mode;
a detecting circuit, connected to the inductive boost circuit and used in different display modes for selecting different detecting resistors for the different display modes so as to provide different detecting currents in the inductive boost circuit; and
a controller used for providing a pulse width modulation signal so as to drive the inductive boost circuit, and for detecting whether a detecting voltage corresponding to the detecting current exceeds a reference voltage, the controller including a GATE end connected to the inductive boost circuit and a current detection input end connected to the detecting circuit; and
wherein the display modes comprise a 2D display mode and a 3D display mode, and
wherein when an inductive peak current I pk _ 2D of the 2D display mode inductive boost circuit is larger than an inductive peak current I pk _ 3D of the 3D display mode inductive boost circuit, the detecting circuit further includes:
a first resistor, with one end thereof connected to the ground, and the other end thereof connected to a source of a switching transistor of the inductive boost circuit;
a second resistor, with one end thereof connected to the source of the switching transistor together with the first resistor;
a first switching transistor, with a drain thereof connected to the other end of the second resistor, and a source thereof connected to the ground;
a third resistor; and
a second switching transistor, with a grid thereof connected to the 2D/3D switching signal input end, a drain thereof connected to a voltage supply via the third resistor and further to a grid of the first switching transistor, and a source thereof connected to the ground.
3. The LED boost converter according to claim 1 , wherein the resistance values of the first resistor and the second resistor respectively are calculated by:
R
1
=
(
R
2
D
,
R
3
D
)
max
R
2
=
R
2
D
R
3
D
R
2
D
-
R
3
D
wherein, R 2D and R 3D are the detecting resistance values in the 2D display mode and the 3D display mode respectively, which are calculated by:
R
2
D
=
U
p
I
p
k
_
2
D
R
3
D
=
U
p
I
p
k
_
3
D
wherein, U p is the reference voltage of the controller, and I pk _ 2D and I pk _ 3D are the inductive peak currents of the inductive boost circuit in the 2D display mode and 3D display mode respectively, which are calculated by:
I
p
k
_
2
D
=
I
O
_
2
D
+
V
o
_
2
D
V
IN
+
2
V
I
N
(
V
O
_
2
D
-
V
IN
)
LfV
O_
2
D
I
p
k
_
3
D
=
I
O
_
3
D
+
V
o
_
3
D
V
IN
+
2
V
I
N
(
V
O
_
3
D
-
V
IN
)
LfV
O
_
3
D
wherein, I o _ 2D and V o _ 2D are the current and the voltage needed by the LED in the 2D display mode respectively, I o _ 3D and V o _ 3D are the current and the voltage needed by the LED in the 3D display mode respectively, V IN is the input voltage, L is the inductive value of the inductive boost circuit, and f is a switching frequency of the switching transistor of the inductive boost circuit.
4. The LED boost converter according to claim 1 , wherein the resistance values of the first resistor and the second resistor respectively are calculated by:
R
1
=
(
R
2
D
,
R
3
D
)
max
R
2
=
R
2
D
R
3
D
R
2
D
-
R
3
D
wherein, R 2D and R 3D are the detecting resistance values in the 2D display mode and the 3D display mode respectively, which are calculated by:
R
2
D
=
U
p
I
p
k
_
2
D
R
3
D
=
U
p
I
p
k
_
3
D
wherein, U P is the reference voltage of the controller, and I pk _ 2D and I pk _ 3D are the inductive peak currents of the inductive boost circuit in the 2D display mode and 3D display mode respectively, which are calculated by:
I
p
k
_
2
D
=
I
O
_
2
D
+
V
o
_
2
D
V
IN
+
2
V
I
N
(
V
O
_
2
D
-
V
IN
)
LfV
O_
2
D
I
p
k
_
3
D
=
I
O
_
3
D
+
V
o
_
3
D
V
IN
+
2
V
I
N
(
V
O
_
3
D
-
V
IN
)
LfV
O
_
3
D
wherein, I o _ 2D and V o _ 2D are the current and the voltage needed by the LED in the 2D display mode respectively, I o _ 3D and V o _ 3D are the current and the voltage needed by the LED in the 3D display mode respectively, V IN is the input voltage, L is the inductive value of the inductive boost circuit, and f is a switching frequency of the switching transistor of the inductive boost circuit.
5. The LED boost converter according to claim 1 , wherein
when the 2D/3D switching signal input end outputs a 2D signal, the first switching transistor is cut off, and the detecting resistance value in the 2D display mode equals the resistance value of the first resistor; and
when the 2D/3D switching signal input end outputs a 3D signal, the first switching transistor is switched on, and the detecting resistance in the 3D display mode equals the resistance value of the first resistor and the second resistor in parallel.
6. The LED boost converter according to claim 1 , wherein
when the 2D/3D switching signal input end outputs a 2D signal, the second switching transistor is cut off and the first switching transistor is switched on, and the detecting resistance value in the 2D display mode equals the resistance value of the first resistor and the second resistor in parallel; and
when the 2D/3D switching signal input end outputs a 3D signal, the first switching transistor is cut off and the second switching transistor is switched on, and the detecting resistance value in the 3D display mode equals the resistance value of the first resistor.
7. An LED backlight driver, comprising:
an inductive boost circuit used in different display modes for boosting an input voltage to a working voltage necessary for the operation of an LED in a current display mode;
a detecting circuit, connected to the inductive boost circuit and used in different display modes for selecting different detecting resistors for the different display modes so as to provide different detecting currents in the inductive boost circuit; and
a controller used for providing a pulse width modulation signal so as to drive the inductive boost circuit, and for detecting whether the detecting voltage corresponding to the detecting current exceeds a reference voltage, the controller including a GATE end connected to the inductive boost circuit and a current detection input end connected to the detecting circuit; and
wherein the display modes comprise a 2D display mode and a 3D display mode, and
wherein when an inductive peak current I pk _ 2D of the 2D display mode inductive boost circuit is smaller than an inductive peak current I pk _ 3D of the 3D display mode inductive boost circuit, the detecting circuit further includes:
a first resistor, with one end thereof connected to a ground, and the other end thereof connected to a source of the switching transistor in the inductive boost circuit;
a second resistor, with one end thereof connected to the source of the switching transistor together with the first resistor; and
a first switching transistor, with a grid thereof connected to the 2D/3D switching signal input end, a drain thereof connected to the other end of the second resistor, and a source thereof connected to the ground.
8. An LED backlight driver, comprising:
an inductive boost circuit used in different display modes for boosting an input voltage to a working voltage necessary for the operation of an LED in a current display mode;
a detecting circuit, connected to the inductive boost circuit and used in different display modes for selecting different detecting resistors for the different display modes so as to provide different detecting currents in the inductive boost circuit; and
a controller used for providing a pulse width modulation signal so as to drive the inductive boost circuit, and for detecting whether the detecting voltage corresponding to the detecting current exceeds a reference voltage, the controller including a GATE end connected to the inductive boost circuit and a current detection input end connected to the detecting circuit; and
wherein the display modes comprise a 2D display mode and a 3D display mode, and
wherein when an inductive peak current I pk _ 2D of the 2D display mode inductive boost circuit is larger than an inductive peak current I pk _ 3D of the 3D display mode inductive boost circuit, the detecting circuit further includes:
a first resistor, with one end thereof connected to the ground, and the other end thereof connected to a source of a switching transistor in the inductive boost circuit;
a second resistor, with one end thereof connected to the source of the switching transistor together with the first resistor;
a first switching transistor, with a drain thereof connected to the other end of the second resistor, and a source connected to the ground reference;
a third resistor; and
a second switching transistor with a grid thereof connected to the 2D/3D switching signal input end, a drain thereof connected to a voltage supply via the third resistor, and further to a grid of the first switching transistor, and a source thereof connected to the ground.