KR100928477B1 - Apparatus for driving light emitting diode and method for driving the same - Google Patents

Abstract

PURPOSE: A method and a device for driving an LED are provided to suppress an overcurrent due to disconnection of a line by controlling the on/off of the switches according to the size of the unit driving current supplied to each LED group. CONSTITUTION: A driving switching element(Tr) switches a driving current according to a driving voltage. A sensing resistor(Rs) is connected between the source electrode of the driving switching element and the first node. The driving integrated circuit(DIC) controls the size of the driving voltage according to the sensing voltage of both ends of the sensing resistance. A plurality of switches(S1-S3) are connected to the first node. The plurality of control resistors(Rc1-Rc3) are connected to the plurality of switches. The plurality of control resistors are commonly connected to the first node. The plurality of LED groups(LGR1-LGR3) receives the plurality of unit driving currents. A driving current controller(DCC) controls the on/off of the switches according to the size of the unit driving current supplied to each LED group.

Description

Light emitting diode driving device and driving method thereof {APPARATUS FOR DRIVING LIGHT EMITTING DIODE AND METHOD FOR DRIVING THE SAME}

The present invention relates to a light emitting diode driving apparatus, and more particularly, to a light emitting diode driving apparatus and a driving method thereof capable of preventing damage to the light emitting diode from an overcurrent.

In general, when lighting a light emitting diode (Light Emitting Diode) to turn on, the temperature rise of the junction (Junction) should be considered.

When driving the LEDs connected in parallel, when a line in one LED group is disconnected, a driving current is supplied into the remaining LED groups except for the LED group including the disconnected line. Therefore, the light emitting diodes in the remaining light emitting diode groups are supplied with a relatively large driving current. As a result, a problem arises in that the temperature of the junction surface of the light emitting diode rises and the light emitting diode is broken.

The present invention has been made to solve the above problems, and detects the magnitude of the unit driving current supplied to each LED group, and controls the on / off of the switches in accordance with the detection result of the disconnection of the line It is an object of the present invention to provide a light emitting diode driving apparatus capable of suppressing the generation of overcurrent and a driving method thereof.

A light emitting diode driving apparatus according to the present invention for achieving the above object, the drive switching element for switching the drive current according to the drive voltage sense resistor connected between the source electrode and the first node of the drive switching element the sense resistor A plurality of switches commonly connected to the first node. A plurality of switches commonly connected to the first node are independently connected to each of the switches and are commonly connected to the first node. A plurality of control resistors a plurality of light emitting diode groups each receiving a plurality of unit driving currents divided from a driving current switched by the driving switching element, sensing a magnitude of a unit driving current supplied to each of the light emitting diode groups, According to the detection result, the driving current controller which controls the on / off of the switches is included. Characterized in that.

Each LED group includes a plurality of LED chips connected in series with each other, and a terminal resistor connected to each of the LED chips located at the outermost side of each LED group, and at the other outermost edge of each LED group. Each of the located light emitting diode chips is commonly connected to a second node, and each light emitting diode chip includes a plurality of light emitting diodes connected in parallel with each other.

The driving current controller includes a driving winding connected in series to one end of each of the terminal resistors of each LED group, and each switch is turned on or off according to a unit driving current flowing through the corresponding driving winding, One side of each driving winding is commonly connected to the third node.

The driving current control unit further includes a diode connected in parallel to each driving winding, and each diode is connected to the driving winding so as to be disposed in a reverse direction with respect to the light emitting diode included in each light emitting diode group. do.

High frequency bypass ultrafast diode connected between the drain electrode of the driving switching element and the second node A high frequency current control inductor connected between the drain electrode and the third node Connects between the first node and the third node A first power factor improving diode connected between the second node and the fourth node; a second power factor improving diode and a first resistor connected in series between the fourth node and the fifth node; A third power factor improving diode connected between the first node and the fifth node. A first rectifying filter capacitor connected between the second node and the fifth node. The third rectifier filter capacitor connected between the first node and the fourth node. 2 Rectifier filter capacitor Rectifying bridge diode connected between the first node, the second node, the sixth node and the seventh node The sixth furnace A first anti-electromagnetic capacitor connected between the ground and a seventh node; a second anti-electromagnetic capacitor connected between the ground and a seventh node; a first anti-noise capacitor connected between the sixth node and the seventh node; Noise filter for suppressing electromagnetic waves connected between the seventh node, the eighth node, and the ninth node A first input terminal to which the first AC power supply for surge protection semiconductor resistance element connected in parallel between the eighth node and the ninth node is supplied A second input terminal supplied with a fuse second AC voltage connected between the second node and the eighth node and a load protection thermistor connected between the ninth node, a PWM dimming terminal, an internal power supply terminal, and a linear dimming terminal of the driving integrated circuit The reset terminal of the driving integrated circuit and the ground capacitor connected between the tenth node and the first node which are commonly connected to each other. A grounding resistor connected between the one node, a grounding terminal of the driving integrated circuit is connected to the first node, and an output terminal of the driving integrated circuit is connected to a gate electrode of the driving switching element; The current sensor input terminal is connected to the source electrode of the driving switching element, and the input terminal of the driving integrated circuit is connected to the second node.

In addition, the driving method of the light emitting diode driving apparatus according to the present invention for achieving the above object, between the drive switching element for generating a drive current according to the drive voltage, between the source electrode and the first node of the drive switching element; A driving integrated circuit for controlling the magnitude of the driving voltage according to a connected sense resistor, a sense voltage across the sense resistor, a plurality of switches commonly connected to the first node, and a plurality of switches respectively. A light emitting device includes a plurality of light emitting diode groups, each independently connected and a plurality of control resistors commonly connected to a first node, and a plurality of light emitting diode groups each of which receives a plurality of unit driving currents divided from a driving current from the driving switching device. A method of driving a diode driving device, the method comprising: sensing the magnitude of a unit driving current supplied to each of the LED groups And controlling the on / off of the switches according to the sensing result.

The LED driving apparatus and driving method thereof according to the present invention have the following effects.

In the present invention, the magnitude of the unit driving current supplied to each LED group can be sensed, and the on / off of the switches can be controlled according to the detection result to suppress generation of overcurrent due to disconnection of the line. Therefore, breakage of the light emitting diode can be prevented.

1 is a view showing a light emitting diode driving apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the LED driving apparatus according to the present invention includes a driving switching element Tr generating a driving current according to a driving voltage, a source electrode SE of the driving switching element Tr, and a first switching element. A sensing resistor Rs connected between one node n1, a driving integrated circuit DIC for adjusting a magnitude of the driving voltage according to a sensing voltage across the sensing resistor Rs, and the first node A plurality of switches S1, S2, and S3 commonly connected to n1 and a plurality of switches independently connected to each of the switches S1, S2, and S3, and commonly connected to the first node n1. A plurality of light emitting diode groups LGR1, LGR2, and LGR3, each of which receives a plurality of unit driving currents divided from the control resistors Rc1, Rc2, and Rc3 and the driving current from the driving switching element Tr. And the unit driving current supplied to each of the LED groups LGR1, LGR2, and LGR3. Sense, and it includes a drive current controller (DCC) for controlling the on / off state of the switches (S1, S2, S3) according to the detection result.

Each LED group LGR1, LGR2, LGR3 includes a plurality of light emitting diode chips LC and one terminal resistor Rt1, Rt2, and Rt3 connected in series with each other. Although three light emitting diode groups are shown in FIG. 1, the present invention may include two or more light emitting diode groups.

Here, the plurality of light emitting diode chips LC included in one light emitting diode group are connected to each other in series, so that the light emitting diode chips LC positioned at one outermost side of the light emitting diode chips LC, that is, FIG. According to 2, the uppermost light emitting diode chip LC is connected to the first node n1. In other words, each of the light emitting diode chips LC located at the top of each of the light emitting diode groups LGR1, LGR2, and LGR3 is commonly connected to the second node n2.

In addition, the terminal resistance included in one light emitting diode group is the light emitting diode chip LC located at the outermost side of the other light emitting diode chips LC located in the light emitting diode group, that is, the lowermost portion according to FIG. 2. It is connected to the light emitting diode chip LC located.

Meanwhile, each light emitting diode chip LC includes a plurality of light emitting diodes LD connected in parallel with each other. Although one light emitting diode chip LC includes three light emitting diodes LD in FIG. 1, each light emitting diode chip LC according to the present invention may include two or more light emitting diodes LD.

In particular, the driving current controller DCC includes a plurality of driving windings CO1, CO2, and CO3 and a plurality of diodes D1, D2, and D3.

One side of each of the driving windings CO1, CO2, and CO3 is connected to one side of the terminal resistors Rt1, Rt2, and Rt3 provided in each of the light emitting diode groups LGR1, LGR2, and LGR3. The other side of each of the driving windings CO1, CO2, and CO3 is commonly connected to the third node n3. In other words, each of the driving windings CO1, CO2, and CO3 is connected to one side of each of the terminal resistors Rt1, Rt2, and Rt3 and the third node n3. Each of the driving windings CO1, CO2, and CO3 is used to detect whether the unit driving current is normally supplied to each of the LED groups LGR1, LGR2, and LGR3. One driving winding is responsible for one LED group. Then, it is detected whether the unit driving current is normally supplied to the light emitting diode chips LC in the light emitting diode group.

When a unit driving current is normally supplied to one LED group, a unit driving current flows normally in the driving winding, and a magnetic force is generated in the driving winding according to the unit driving current. Make it on On the other hand, when an abnormality such as a disconnection occurs in one LED group and the unit driving current is not normally supplied, the unit driving current does not flow through the driving winding, and magnetic force is no longer generated from the driving wire. The switch is turned off.

One driving winding is responsible for turning on and off one switch. 3 shows three drive windings and three switches corresponding to each of them. The number of these windings and switches for driving varies depending on the number of LED groups.

On the other hand, this drive winding is located close to the switch to supply the magnetic force described above as a coil to the switch. That is, FIG. 2 is a view showing a reed relay switch. As shown in FIG. 2, the pair of driving windings CO1 and the switch S1 in the present invention function as a reed relay switch. do. In the present invention, one reed relay switch determines whether there is a unit driving current in one LED group, and drives switching by controlling the combined resistance values of the control resistors Rc1, Rc2, and Rc3 according to the determination result. The magnitude of the voltage to be applied to the source electrode SE of the device Tr is controlled.

In addition, diodes D1, D2, and D3 connected in parallel to the respective driving windings CO1, CO2, and CO3 are included. In order to prevent this, the driving winding is connected to have a reverse direction with respect to the light emitting diodes LD included in each of the light emitting diode groups LGR1, LGR2, and LGR3.

On the other hand, the light emitting diode driving apparatus according to the present invention, the high-speed bypass ultrafast diode (HD) connected between the drain electrode (DE) of the drive switching element (Tr) and the second node (n2), and the drain A high frequency current control inductor L2 connected between the electrode DE and the third node n3, and a load stabilization electrolytic capacitor C9 connected between the second node n2 and the third node n3. ), A first power factor improving diode D4 connected between the second node n2 and the fourth node n4, and the fourth node n4 and the fifth node n5 in series with each other. A second power factor improving diode D5 and a first resistor R1 connected to each other, a third power factor improving diode D6 connected between the first node n1 and the fifth node n5, and And a first rectifying filter capacitor C5 connected between the second node n2 and the fifth node n5, and the first node n1 and the fourth node n4. A rectifying bridge diode connected between a second rectifying filter capacitor C8 connected to the first node n1, a second node n2, a sixth node n6, and a seventh node n7. (BD), a first electromagnetic wave preventing capacitor C3 connected between the sixth node n6 and earth, and a second electromagnetic wave preventing capacitor connected between the ground and the seventh node n7 ( C4), the first noise preventing capacitor C2 connected between the sixth node n6 and the seventh node n7, the sixth node n6, the seventh node n7, and the seventh node. Electromagnetic wave suppression noise filter L1 connected between the eighth node n8 and the ninth node n9, and a surge protection semiconductor resistor connected in parallel between the eighth node n8 and the ninth node n9. A component RV, a fuse FS connected between the first input terminal to which the first AC power source AC1 is supplied, and the eighth node n8, and a second to which the second AC voltage AC2 is supplied; Input terminal and above A load protection thermistor connected between the ninth node n9; TH) and a grounding capacitor connected between the tenth node n10 and the first node n1, in which the PWM dimming terminal, the internal power supply terminal, and the linear dimming terminal of the driving integrated circuit DIC are connected to each other in common. And a grounding resistor R2 connected between the reset terminal of the driving integrated circuit DIC and the first node n1.

The ground terminal of the driving integrated circuit DIC is connected to the first node n1, and the output terminal of the driving integrated circuit DIC is connected to the gate electrode of the driving switching element Tr. The current sensor input terminal of the integrated circuit DIC is connected to the source electrode SE of the driving switching element Tr, and the input terminal of the driving integrated circuit DIC is connected to the second node n2.

The bridge diode BD includes four diodes D7 connected to each other.

The light emitting diode driving apparatus shown in FIG. 2 is a light emitting diode lighting ballast using a driving integrated circuit (DIC) of the HV9910. The driving integrated circuit (DIC) has a total of eight pins (first to eighth pins). . That is, the driving integrated circuit DIC includes an input terminal corresponding to the first pin, a current sensor input terminal corresponding to the second pin, a ground terminal corresponding to the third pin, an output terminal corresponding to the fourth pin, and a fifth The PWM dimming terminal corresponding to the pin, the internal power supply terminal corresponding to the sixth pin, the linear dimming terminal corresponding to the seventh pin, and the reset terminal corresponding to the eighth pin are included.

The driving integrated circuit DIC outputs a pulse width modulation (PWM) signal through an output terminal, and supplies the PWM signal to the gate electrode of the driving switching device Tr. At this time, the duty ratio of the PWM signal is changed by the voltage across the sensing resistor Rs, and the voltage formed across the sensing resistor Rs is the drain electrode of the driving switching element Tr. As the drain current increases due to some cause, the voltage across both ends of the sense resistor Rs also increases because it is proportional to the current flowing in DE). The voltage across the sense resistor Rs is also reduced.

When the voltages formed at both ends of the sensing resistor Rs are supplied to the current sensor input terminal of the driving integrated circuit DIC, the PWM signal from the driving integrated circuit DIC is transferred to the driving switching element Tr through the output terminal. Is supplied to the gate electrode.

The pulse width of the PWM signal supplied to the gate electrode of the driving switching element Tr is controlled by the voltage input through the current sensor input terminal. If the voltage is high, the pulse width of the PWM signal is narrowed (duty ratio). On the other hand, the lower this voltage, the wider the pulse width of the PWM signal (duty duty ratio). As a result, the magnitude of the drain current flowing through the driving switching element Tr is controlled by the voltage across the sensing resistor Rs.

According to the present invention, the voltage across the sensing resistor Rs, that is, the voltage of the source electrode SE is changed according to the unit driving current in the LED group. When described in detail with reference to Figures 3a and 3b as follows.

3A is a diagram for explaining an operation when a line in any one LED group is disconnected.

FIG. 3A illustrates a state in which a line in the first LED group LGR1 is disconnected among the three LED groups LGR1, LGR2, and LGR3. Accordingly, the unit driving current cannot be supplied into the first LED group LGR1. Therefore, the driving current supplied to the LED groups LGR1, LGR2, and LGR3 through the drain electrode of the driving switching element Tr is divided into two unit driving currents instead of three, and each divided unit driving current is divided into two. Are supplied to the second light emitting diode group LGR2 and the third light emitting diode group LGR3, respectively. At this time, in the related art, each of the two unit driving currents has a problem of further increasing, but the present invention prevents the unit driving current from increasing as follows.

That is, when the line in the first LED group LGR1 is disconnected, the first LED group LGR1 is no longer able to call a unit driving current, and the first LED group LGR1 is in a state. Magnetic force is not generated from the driving winding CO1. Then, the first switch S1 constituting one reed relay switch together with the first driving winding CO1 is turned off. As the first switch S1 is turned off, the first control resistor and the source electrode SE are electrically separated from each other, thereby increasing the combined resistance value applied to the source electrode SE.

Comparing the synthetic resistance value in the normal state in which no disconnection occurs in any LED group and the synthetic resistance value in the state as shown in FIG. 3A is as follows. Here, assume that the resistance values of the first to third control resistors are all the same as Rx.

In the normal state in which disconnection does not occur in any LED group, the combined resistance value Rn is expressed by Equation 1 below.

Rn = (Rs * Rx / 3) / (Rs + Rx / 3)

As shown in FIG. 3A, the combined resistance value Rcut1 when the line of the first LED group LGR1 is disconnected is represented by Equation 2 below.

Rcut1 = (Rs * Rx / 2) / (Rs + Rx / 2)

As can be seen by comparing the synthesis resistance value according to Equation 1 and the synthesis resistance value according to Equation 2, it can be seen that the synthesis resistance value according to Equation 2 is larger than the synthesis resistance value according to Equation 1. That is, since the sense resistor Rs and the first to third control resistors Rc1, Rc2, and Rc3 are connected in parallel with each other, the total synthesized resistance value increases as these resistors are electrically disconnected from the circuit.

As the synthesis resistance increases, the voltage across the sensing resistor Rs in FIG. 3A increases more than the voltage across the sensing resistor Rs in FIG. 1. Accordingly, the driving integrated circuit DIC in FIG. 3A outputs a PWM signal having a lower pulse width than the driving integrated circuit DIC in FIG. 1. Accordingly, the driving switching element Tr in FIG. 3A provides a lower driving current (drain current) than the driving switching element Tr in FIG. 1. As a result, the driving current in FIG. 3A is lower than the driving current in FIG. 1, and the magnitude of each unit driving current supplied to the second and third light emitting diode groups LGR3 by being divided therefrom as the driving current decreases. Since it becomes low, generation | occurrence | production of the overcurrent by the disconnection of a circuit is suppressed.

FIG. 3B is a diagram for describing an operation when lines in any two LED groups are disconnected.

3B illustrates a state in which lines in the first and second light emitting diode groups LGR2 of the three light emitting diode groups LGR1, LGR2 and LGR3 are disconnected. Accordingly, the unit driving current cannot be supplied into the first and second LED groups LGR2. Therefore, the driving current supplied to the LED groups LGR1, LGR2, and LGR3 through the drain electrode of the driving switching device Tr is supplied to the third LED group LGR3 as it is. At this time, the present invention controls the magnitude of the driving current as follows so that this large value of driving current is not supplied to the third LED group LGR3 as it is.

That is, when the lines in the first and second LED groups LGR1 and LGR2 are disconnected, the unit driving current can no longer be called to the first and second LED groups LGR1 and LGR2. No magnetic force is generated from the first driving winding CO1 in the first light emitting diode group LGR1 and the second driving winding CO2 in the second light emitting diode group LGR2. Then, the second switch constituting one reed relay switch together with the first switch S1 constituting one reed relay switch together with the first driving reel CO1 and the second driving reel CO2 ( As S2 is turned off, the first and second control resistors Rc1 and Rc2 and the source electrode SE are electrically separated from each other, thereby increasing the combined resistance value applied to the source electrode SE.

As shown in FIG. 3B, the combined resistance values Rcut1 and 2 when the lines of the first and second LED groups LGR1 and LGR2 are disconnected are represented by Equation 3 below.

Rcut1,2 = (Rs * Rx) / (Rs + Rx)

As can be seen by comparing the composite resistance values according to Equations 1 and 2 with the composite resistance values according to Equation 3, it is understood that the synthetic resistance values according to Equation 3 are larger than the synthetic resistance values according to Equations 1 and 2, respectively. Can be. That is, since the sense resistors Rs and the first to first control resistors Rc1, Rc2, and Rc3 are connected in parallel to each other, the total synthesized resistance value increases as these resistors are electrically disconnected from the circuit.

On the other hand, although not shown, when the line in the third LED group LGR3 is disconnected, the third switch S3 is turned off.

As described above, in the present invention, whether the line in the LED group is disconnected is checked and the value of the driving current is controlled by adjusting the synthesis resistance accordingly. Therefore, damage to the light emitting diodes can be prevented by preventing overcurrent protection due to line breakage.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of.

1 is a view showing a light emitting diode driving apparatus according to an embodiment of the present invention;

2 shows a reed relay switch

3A is a diagram for explaining an operation when a line in any one LED group is disconnected.

3B is a view for explaining an operation when lines in any two LED groups are disconnected;

Claims (6)

A driving switching element for switching the driving current according to the driving voltage; A sense resistor connected between the source electrode of the driving switching element and the first node; A driving integrated circuit configured to adjust a magnitude of the driving voltage in accordance with a sensing voltage across the sensing resistor; A plurality of switches commonly connected to the first node; A plurality of control resistors independently connected to each of the switches and commonly connected to the first node; A plurality of light emitting diode groups each receiving a plurality of unit driving currents divided from the driving current switched by the driving switching element; And a driving current controller for sensing the magnitude of the unit driving current supplied to each of the LED groups and controlling the on / off of the switches according to the detection result. The method of claim 1, Each light emitting diode group includes a plurality of light emitting diode chips connected in series with each other, and a terminal resistor connected to each of the light emitting diode chips located at the outermost side of each light emitting diode group; Each of the light emitting diode chips located at the outermost side of each light emitting diode group is commonly connected to a second node; And, Each light emitting diode chip includes a plurality of light emitting diodes connected in parallel with each other. The method of claim 2, The drive current control unit A drive winding connected in series to one side of each of the terminal resistors of each group of LED groups; Each switch is turned on or off depending on the unit drive current flowing in the corresponding drive winding; And, A light emitting diode drive device, characterized in that one side of each drive winding is commonly connected to a third node. The method of claim 3, wherein The drive current control unit, A diode further connected in parallel to each drive winding; And, Wherein each diode is connected to the driving winding so as to be arranged in a reverse direction with respect to the light emitting diodes included in each light emitting diode group. The method of claim 4, wherein An ultra fast diode for high frequency bypass connected between the drain electrode of the driving switching element and the second node; A high frequency current control inductor connected between the drain electrode and the third node; A load stabilizing electrolytic capacitor connected between the second node and the third node; A first power factor improving diode connected between the second node and a fourth node; A second power factor improving diode and a first resistor connected in series between the fourth node and the fifth node; A third power factor improving diode connected between the first node and the fifth node; A first rectifying filter capacitor connected between the second node and the fifth node; A second rectifying filter capacitor connected between the first node and the fourth node; A rectifying bridge diode connected between the first node, the second node, a sixth node, and a seventh node; A first electromagnetic wave preventing capacitor connected between the sixth node and a ground; A second electromagnetic wave preventing capacitor connected between the ground and a seventh node; A first noise preventing capacitor connected between the sixth node and the seventh node; A noise filter for suppressing electromagnetic waves connected between the sixth node, the seventh node, the eighth node, and the ninth node; A surge protection semiconductor resistance element connected in parallel between the eighth node and the ninth node; A fuse connected between the first input terminal to which the first AC power is supplied and the eighth node; A load protection thermistor connected between a second input terminal supplied with a second AC voltage and the ninth node; A grounding capacitor connected between the first node and a tenth node having a common PWM dimming terminal, an internal power supply terminal, and a linear dimming terminal of the driving integrated circuit; A grounding resistor connected between the reset terminal of the drive integrated circuit and the first node; A grounding terminal of the driving integrated circuit is connected to the first node; An output terminal of the driving integrated circuit is connected to a gate electrode of the driving switching element; A current sensor input terminal of the driving integrated circuit is connected to a source electrode of the driving switching element; And an input terminal of the driving integrated circuit is connected to a second node. The magnitude of the driving voltage is varied according to a driving switching device for generating a driving current according to a driving voltage, a sensing resistor connected between a source electrode of the driving switching device and a first node, and a sensing voltage across both ends of the sensing resistor. A driving integrated circuit for controlling, a plurality of switches commonly connected to the first node, a plurality of control resistors independently connected to each of the switches and commonly connected to the first node, and the drive switching A driving method of a light emitting diode driving apparatus comprising a plurality of light emitting diode groups each receiving a plurality of unit driving currents divided from a driving current from an element, Detecting a magnitude of a unit driving current supplied to each of the LED groups; And, And controlling the on / off of the switches according to the detection result.

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