KR101547898B1 - Led driving device - Google Patents

Abstract

The LED driving apparatus according to the present invention includes a driving circuit for converting input power into a driving voltage and providing the LED to the LED module, a sensing unit disposed between the driving circuit and the LED module for sensing a driving voltage provided to the LED module, And a protection circuit part including a first switch connected between the sensing part and the LED module, wherein the protection circuit part turns off the first switch when the driving voltage from the sensing part is equal to or higher than a predetermined first reference voltage, .

Description

LED DRIVING DEVICE

The present invention relates to an LED driving apparatus.

FPD (Flat Display Panel) As demand for TVs grows, demand for LED TVs also increases. As a result, efforts have been made to reduce the price of power supply units (SMPS) for TVs. In particular, there is an increasing need for cost reduction of LED drivers as well as cost reduction of existing power conversion converters.

Conventionally, a boost topology type LED driver has been widely used, but a buck topology type LED driver which is less expensive than a boost type LED driver has been developed.

That is, in order to supply power to an LED module having a plurality of LEDs, a buck converter, which is less expensive than an expensive insulated converter, is used to control a current flowing through the LED module by a constant current method.

However, in the case of an LED driving apparatus using a buck converter, there is no element that can control the current flowing in the LED module when the switch in the path of power supply to the LED module is short. Therefore, There is a possibility that the LED module may be damaged.

The following prior art document, Patent Document 1, relates to an LED driving circuit and method for overvoltage protection and constant current driving. That is, the patent document 1 discloses an invention that can realize an overvoltage protection function by sensing a voltage of an inductor. However, a buck converter is not used as in the present invention, and a configuration for protecting the LED module using a comparator is disclosed not.

Korean Patent Laid-Open No. 10-2011-0136537

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art described above, and it is possible to prevent breakage of the LED module and the driving circuit by blocking power supply to the LED module when the driving voltage is sensed and is higher than a predetermined reference voltage .

According to a first technical aspect of the present invention, there is provided an LED driving apparatus comprising: a driving circuit unit for converting input power into a driving voltage and providing the converted driving voltage to an LED module; A sensing unit positioned between the driving circuit unit and the LED module and sensing a driving voltage provided to the LED module; And a first switch connected between the sensing unit and the LED module; The protection circuit may turn off the first switch when the driving voltage from the sensing unit is equal to or greater than a predetermined first reference voltage.

The apparatus may further include a rectifying unit for rectifying the input power and providing rectified power to the driving circuit unit.

The driving circuit may include a buck converter that converts the input power to a low voltage driving voltage and supplies the driving voltage to the LED module.

The protection circuit may further include a first comparator for comparing the first reference voltage with a driving voltage from the sensing unit.

The first comparator may generate a low signal to turn off the first switch when the driving voltage from the sensing unit is equal to or higher than the first reference voltage.

The protection circuit compares a second reference voltage set in advance with a voltage level of an output signal of the first comparator and outputs a latch state when the voltage level of the output signal of the first comparator is equal to or lower than the second reference voltage A latch circuit portion for holding the latch circuit portion; And a second switch for performing a switching operation according to the output of the first comparator.

The latch circuit may include: a second comparator that compares the voltage level of the output signal of the first comparator with the second reference voltage; And a latch for holding the latch state when the output of the second comparator is low; . ≪ / RTI >

According to a second technical aspect of the present invention, there is provided an LED driving apparatus including: a rectifying unit for rectifying input power; A driving circuit part including a buck converter for converting a voltage from the rectifying part into a driving voltage and providing the voltage to the LED module; A sensing unit positioned between the driving circuit unit and the LED module to sense a driving voltage provided to the LED module; And a protection circuit unit located between the sensing unit and the LED module to prevent the driving voltage from being supplied to the LED module when the driving voltage from the sensing unit is equal to or higher than a predetermined first reference voltage have.

The protection circuit may include: a first comparator that compares a driving voltage from the sensing unit with the first reference voltage; And a plurality of switches connected between the sensing unit and the LED module and performing a switching operation according to an output of the first comparator; .

The first comparator may output a low signal to turn off the plurality of switches when the driving voltage from the sensing unit is equal to or higher than the first reference voltage.

The protection circuit includes a second comparator for receiving an output signal of the first comparator and comparing the voltage level of the output signal with a preset reference voltage; And a latch for holding the latch state when the output of the second comparator is low; As shown in FIG.

The LED driving apparatus according to the present invention detects a driving voltage provided to the LED module in the sensing unit and cuts off the power supply to the LED module when the reference voltage is equal to or higher than a preset reference voltage, .

1 is a block diagram of an LED driving apparatus according to an embodiment of the present invention.
2 is a block diagram of an LED driving apparatus according to another embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

1 is a block diagram of an LED driving apparatus according to an embodiment of the present invention.

Referring to FIG. 1, the LED driving apparatus according to the present invention may include a rectifying unit 100, a driving circuit unit 200, a sensing unit 300, a protection circuit unit 400, and an LED module 500.

At this time, the rectifying unit 100 may rectify the input power and output the rectified power. The driving circuit unit 200 converts the power supplied from the rectifying unit 100 into a driving voltage and provides the driving voltage to the LED module 500.

Meanwhile, the LED driving apparatus according to the present invention may further include an EMI filter 110 for removing noise. The driving circuit unit 200 includes a PFC 210 for compensating a power factor, a buck converter 220 for converting an input power source to a driving voltage of a low voltage and providing the driving voltage to the LED module 500, And a buck controller 230 for controlling the converter.

That is, when the AC input power source is inputted, noise can be removed through the EMI filter 110 and supplied to the rectifier unit 100. After that, the rectified voltage is converted into DC power by the rectifier 100 and then input to the power factor correction circuit part 210 for power factor correction and then input to the buck converter 220. In the buck converter 220, the input power may be converted into a low voltage driving voltage and may be provided to the LED module 500.

However, in the case of an LED driving apparatus without the conventional protection circuit unit 400, a method of controlling the current of the LED module 500 by the switching operation of the switch 240 through the coil 510 is configured. That is, when the switch 240 is turned on, the current flowing through the coil 510 gradually increases. When the predetermined current value is reached, the switch 240 is turned off, The current flowing through the coil 510 is gradually reduced. The above-described turn-on / off operation of the switch 240 is repeated, so that the current flowing through the LED module 500 can be constantly controlled.

However, if the drain-source of the switch 240 is short-circuited, there is no element that can control the current flowing in the LED module 500, The current flowing through the coil 500 and the coil 510 increases. There is a problem that the LED module 500 may be broken.

Accordingly, the LED driving apparatus of the present invention may further include the sensing unit 300 and the protection circuit unit 400 in the above-described configuration.

The sensing unit 300 may be positioned between the driving circuit unit 200 and the LED module 500 and sense a driving voltage provided to the LED module 500. The protection circuit unit 400 may include a first switch 410 connected between the sensing unit 300 and the LED module 500. When the driving voltage from the sensing unit 300 is a pre- The first switch 410 may be turned off if the first reference voltage Vref1 is greater than the first reference voltage Vref1.

More specifically, the protection circuit 400 may further include a first comparator 420 for comparing the first reference voltage Vref1 with a driving voltage from the sensing unit 300.

The sensing unit 300 senses a driving voltage provided to the LED module 500 from the driving circuit unit 200 and provides the sensed driving voltage to the first comparator 420. The first comparator compares a first reference voltage Vref1 set in advance with a driving voltage from the driving circuit unit 200 and generates a low signal when the driving voltage is equal to or higher than the first reference voltage Vref1, The first switch 410 may be turned off. That is, when the driving voltage provided to the LED module 500 is equal to or greater than the first reference voltage Vref1, the first switch 410 is turned off beforehand, thereby cutting off the power supply to the LED module 500 . Thus, it is possible to prevent the LED module 500 from being damaged.

2 is a block diagram of an LED driving apparatus according to another embodiment of the present invention.

Referring to FIG. 2, the protection circuit 400 compares the voltage level of the output signal of the first comparator 420 with the second reference voltage Vref2 set in advance, A latch circuit 440 for maintaining a latch state when the voltage is equal to or lower than the reference voltage Vref2 and a second switch 430 for performing a switching operation according to an output of the first comparator 420. [

The latch circuit 440 may include a second comparator for comparing the voltage level of the output signal of the first comparator with the second reference voltage Vref2 and a second comparator for comparing the voltage level of the output signal of the first comparator with the voltage level of the output signal of the first comparator, And may further include a latch portion.

More specifically, the first comparator 420 may output a low signal when the driving voltage provided from the sensing unit 300 becomes higher than the first reference voltage Vref1.

The second comparator may compare the voltage level of the low signal with the second reference voltage (Vref2), and the latch unit may compare the voltage level of the low signal with the second reference voltage 2 < / RTI > reference voltage Vref2, the latch state can be maintained.

Meanwhile, the second comparator may output a low signal, and the low signal may be input to the second switch 430 to turn off the second switch 430. Accordingly, the first switch 410 may be turned off, thereby preventing power supply to the LED module 500, thereby preventing damage to the LED module 500.

That is, the LED driving apparatus including the buck converter 220 according to the present invention detects the driving voltage provided to the LED module 500 in the sensing unit 300, The LED module 500 and the driving circuit unit 200 can be prevented from being damaged by including the protection circuit unit 400 that cuts off the power supply to the LED module 500 when the voltage is equal to or greater than the reference voltage Vref1.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

100: rectification part
200:
300:
400: protection circuit
410: first switch
420: first comparator
430: second switch
440: latch circuit part
500: LED module

Claims (11)

A driving circuit for converting the input power to a driving voltage and providing the LED to the LED module;
A sensing unit positioned between the driving circuit unit and the LED module and sensing a driving voltage provided to the LED module; And
A protection circuit part including a first switch connected between the sensing part and the LED module; Lt; / RTI >
The protection circuit unit includes:
A first comparator for comparing the first reference voltage with a driving voltage from the sensing unit;
A latch circuit for comparing a second reference voltage set in advance with a voltage level of an output signal of the first comparator and maintaining a latch state when the voltage level of the output signal of the first comparator is lower than the second reference voltage; And
And a second switch for performing a switching operation in accordance with the output of the first comparator,
And turns off the first switch when the driving voltage from the sensing unit is equal to or greater than a predetermined first reference voltage.
The method according to claim 1,
And a rectifier for rectifying the input power source and providing rectified power to the driving circuit unit.
The driving circuit according to claim 1,
And a buck converter for converting the input power to a low voltage drive voltage and supplying the drive voltage to the LED module.
delete The apparatus of claim 1, wherein the first comparator comprises:
And generates a low signal to turn off the first switch when the driving voltage from the sensing unit is equal to or higher than the first reference voltage.
delete The semiconductor memory device according to claim 1, wherein the latch circuit portion
A second comparator for comparing a voltage level of the output signal of the first comparator with the second reference voltage; And
A latch for holding the latch state when the output of the second comparator is low; And the LED driving device.
A rectifying section for rectifying input power;
A driving circuit part including a buck converter for converting a voltage from the rectifying part into a driving voltage and providing the voltage to the LED module;
A sensing unit positioned between the driving circuit unit and the LED module to sense a driving voltage provided to the LED module; And
And a protection circuit unit located between the sensing unit and the LED module and interrupting the supply of the driving voltage to the LED module when the driving voltage from the sensing unit is equal to or higher than a predetermined first reference voltage,
The protection circuit unit includes:
A first comparator for comparing the driving voltage from the sensing unit with the first reference voltage;
A second comparator receiving an output signal of the first comparator and comparing the voltage level of the output signal with a predetermined reference voltage; And
A latch for holding the latch state when the output of the second comparator is low; Further comprising:
9. The semiconductor memory device according to claim 8,
And a plurality of switches connected between the sensing unit and the LED module and performing a switching operation in accordance with the output of the first comparator; Further comprising:
10. The apparatus of claim 9, wherein the first comparator comprises:
And outputs a low signal to turn off the plurality of switches when the driving voltage from the sensing unit is equal to or higher than the first reference voltage.
delete

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