KR20130102830A - Led driving circuit - Google Patents

Abstract

PURPOSE: An LED driving circuit is provided to reduce the size and weight of the LED driving circuit by directly driving an LED with a utility AC voltage without using an SMPS. CONSTITUTION: A rectifier (20) rectifies an AC voltage from a utility AC voltage into a DC voltage. A current commutator (30) applies the DC voltage from the rectifier to a power supply unit. An output controller (60) controls the current which is supplied from the power supply unit to an LED. A current controller (50) controls the current which is supplied to the output controller. An output delay unit (70) delays the current which is supplied from the power supply unit to the LED. [Reference numerals] (10) Power unit; (20) Rectifier; (30) Current commutator; (40) Power supply unit; (50) Current controller; (60) Output controller; (70) Output delay unit; (80) Light-emitting unit

Description

LED DRIVING CIRCUIT

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an LED driving circuit for driving a light emitting unit including at least one light emitting diode (LED), and more particularly to an LED driving circuit capable of driving an LED directly using a commercial AC power source without using a transformer or the like will be.

Recently, with the development of semiconductor technology, light emitting diodes (LEDs) have been mass-produced, and light emitting diodes that consume about 1/10 of the power consumed to obtain the same illuminance as ordinary light bulbs have been attracting attention as eco-friendly energy. However, since the conventional general bulb uses an AC power source of 220V, a separate power source device is not required, but the light emitting diode can be driven only by the DC power source. Therefore, in order to use a light emitting diode device, a switching mode power supply (hereinafter referred to as SMPS) for rectifying an AC power of 220 V to DC and converting a rectified DC voltage into a DC voltage of a required size is essential .

8 schematically shows a circuit configuration of an SMPS used in a conventional LED driving apparatus. Referring to FIG. 8, the SMPS includes a rectifier circuit for rectifying the AC input power, a power transformer for smoothing the current output from the rectification circuit, a power factor adjustment circuit for compensating the power factor degraded by the electrolytic capacitor used for smoothing in the rectification process, A ripple voltage prevention circuit for blocking the ripple voltage between the rectification part and the power supply part, a feedback control circuit for stabilizing the output voltage, an overvoltage and an overcurrent protection circuit, and the like.

However, since the lifetime of an LED is more than 50,000 hours, the life span of a lighting fixture depends on the lifetime of the SMPS, because the life of the electrolytic capacitor included in the SMPS is very short, as is well known. Therefore, even if the LED is a semi-permanent device, there is a problem in that the SMPS needs to be changed several times for the permanent use of the luminaire.

In addition, the power factor adjustment circuit included in the conventional SMPS circuit has a non-polar capacitor for improving the power factor, thereby causing the LED to repeatedly turn on and off, thereby causing the insulation breakdown phenomenon and causing the lighting device to fail.

    It is technically difficult to eliminate the noise phenomenon by the AC input power supply and to keep the harmonic ratio of the power factor adjusting circuit below a proper value only by the pulsating voltage prevention circuit included in the existing SMPS.

    In addition, it is pointed out that the existing SMPS has a problem that it is difficult to apply to the lighting apparatus because the circuit itself is complicated and the volume and weight are increased due to a large number of component parts.

In order to solve such problems, Patent Document 1 discloses an LED driving device and a driving device in which a pulsating current which is inputted through a commercial rectifier (AC) power supply and passed through a bridge rectifier is rectified and smoothed by using a capacitor The constant current is controlled to flow in the first driving unit by limiting the voltage of the pulsating current in the second driving unit and the voltage is limited by cutting the upper waveform according to the voltage of the light emitting unit to supply the constant current of the pulse .

However, according to Patent Document 1, the first driver for limiting the current supplied to the light emitting portion and the second driver for limiting the voltage supplied to the light emitting portion include a plurality of regulators and capacitors, There is a problem as you use it.

In addition, the components of Patent Document 1 can not implement all of the functions of the existing SMPS, which makes it difficult to perfectly cope with the SMPS.

Patent Document 1: Korean Published Patent Application No. 10-2011-0102523 (Publication Date: September 19, 2011)

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a driving apparatus capable of directly driving a light emitting diode with a commercial AC voltage without using an SMPS.

Another object of the present invention is to provide a LED driving circuit having a high power factor and a low harmonic ratio by prolonging the lifetime of the LED for more than 10 years.

It is another object of the present invention to achieve low power consumption and miniaturization of an LED driver circuit.

According to an aspect of the present invention, there is provided an LED driving circuit for driving an LED lamp by supplying a current to the LED lamp, the LED driving circuit comprising: a rectifier for rectifying an AC voltage supplied from a commercial AC voltage to a DC voltage; A power supply unit for supplying a current so that a constant current flows through the at least one LED; A current switching unit for applying the DC voltage provided from the rectifying unit to the power supply unit at a constant voltage regardless of the size of the commercial AC voltage; An output control unit for controlling a current supplied from the power supply unit to the LED so that a constant current flows through the LED; A current controller for detecting an overcurrent and a fluctuating current from a current supplied from a power supply and controlling a current supplied to the output controller; And an output delay unit that receives the rectified DC voltage from the rectifying unit and delays the current from the power supply unit to the LED.

In addition, the power supply of the present invention is an amplifier type current source, the + input terminal connected to the current conversion unit, the output terminal connected to the resistor (R12), connected to the output terminal through the resistor (R8) to form a negative feedback circuit An amplifier comprising an input terminal, the output delay comprising a transistor (Q4) and a resistor (R15) between the rectifier and the LED, a resistor (R13) and a resistor connected between a connection point between the rectifier and the LED and ground; A series connection structure of R14, a collector of the transistor Q4 is connected to the rectifier, an emitter is connected to the resistor R15, and a base is a connection point of the resistor R17 and the resistor R18. The resistor R15 is connected to an output terminal of the amplifier to provide a delayed current to the power supply, and the current controller is a resistor R9 and a p-type transistor between the output terminal of the power supply and ground. The collector of the p-type transistor Q2 is connected to the resistor R9, the base is connected to the output terminal of the power supply unit, the emitter is grounded, and the output control unit is connected between the LED and the ground Wherein the gate of the MOSFET Q1 is connected to the output terminal of the amplifier AMP through a collector of the p-type transistor Q5 and a resistor R12, The source of the MOSFET Q1 is grounded through a resistor R10, and the current flowing through the LED is controlled by a resistor R10.

In addition, the present invention is a p-type transistor (Q5) is a power supply is a transistor type current source, the base is connected to the current switching unit, the collector is connected to the base through the resistor (R11), the emitter is connected to the current control unit The output delay unit includes a transistor Q4 and a resistor R15 between the rectifier and the LED, and a series connection of a resistor R13 and a resistor R14 connected between a connection point between the rectifier and the LED and ground. And a collector of the transistor Q4 connected to the rectifier, an emitter connected to the resistor R15, a base connected to a connection point between the resistor R17 and the resistor R18, and the resistor R15 is connected to the collector of transistor Q5 to provide a delayed current to the power supply, and the current controller includes a resistor R9 and a p-type transistor Q2 between the emitter and ground of the power supply. A collector of the p-type transistor Q2 is connected to the resistor R9, a base is connected to an output terminal of the power supply unit, an emitter is grounded, and an output control unit is connected between the LED and the ground, The base of the p-type transistor Q6 is connected to the emitter of the power supply 40, the collector is connected to the LED, and the emitter is grounded via the resistor R10 , And the current flowing through the LED is controlled by the resistor (R10).

On the other hand, the present invention includes a MOSFET (Q7) the power supply is a MOSFET-type current source, a gate is connected to the current switch, a drain is connected to the gate through a resistor (R11), the source is connected to the current control unit The output delay unit includes a transistor Q4 and a resistor R15 between the rectifier and the LED, and a series connection structure of a resistor R13 and a resistor R14 connected between a connection point between the rectifier and the LED and ground. The collector of the transistor Q4 is connected to the rectifier, the emitter is connected to the resistor R15, the base is connected to the connection point of the resistor R17 and the resistor R18, and the resistor R15 is connected to the rectifier. A current connected to the drain of a MOSFET Q7 to provide a delayed current to the power supply, wherein the current controller includes a resistor R9 and a p-type transistor Q2 between the source and the ground of the power supply; Collector of (Q2) The emitter is grounded and the output control part includes a MOSFET Q1 and a resistor R10 between the LED and the ground, and the MOSFET Q1 and the resistor R10 are connected between the LED and the ground, and the base of the MOSFET Q1 is connected to the output terminal of the power supply part. Q1 is connected to the source of the power supply 40, the drain is connected to the LED, the source is grounded via a resistor R10 and the current flowing through the LED by resistor R10 is controlled .

Meanwhile, the present invention is characterized in that the power supply unit includes a first power supply unit supplying current to a first LED including one or more LEDs and a second power supply unit supplying current to a second LED including one or more LEDs, The control unit includes a first output control unit for controlling the current supplied to the first LED, and a second output control unit for controlling the current supplied to the second LED. The current control unit controls the current supplied to the first output control unit And a second current control unit for controlling the current supplied to the second output control unit, wherein the output delay unit comprises: a first output delay unit for delaying the current delivered from the first power supply unit to the first LED; And a second output delay unit for delaying the current delivered from the second power supply unit to the second LED.

The current switching unit of the present invention includes a switch for transmitting a current to the power supply unit in a different path depending on the magnitude of the commercial AC voltage.

The current switching unit of the present invention includes a resistor R4 and a resistor R5 connected in series between the switch and ground and a resistor R6 and a resistor R7 connected in series between the switch and ground, The switch is connected to one of the resistor R4 and the resistor R6 and the connection point between the resistor R4 and the resistor R5 and the connection point between the resistor R6 and the resistor R7 are connected by a line, And the power supply unit is connected to the line so that a current or voltage is applied to the power supply unit.

Further, in the present invention, a forward diode (D1) is connected between the rectifying part and the LED to prevent reverse flow of current to the LED.

The present invention is characterized in that a capacitor (C1), a diode, and a resistor (R14) are connected between the base of the transistor (Q2) of the current controller and the ground.

The rectifying unit of the present invention is characterized by including a bridge circuit composed of four diodes and a resistor.

As described above, according to the present invention, LED light can be linearly controlled by current to remove noise, have a high power factor, and achieve a low harmonic ratio.

In addition, according to the present invention, the problem that the overcurrent is supplied to the LED to shorten the lifetime of the light emitting diode can be solved, and the smoothing electrolytic capacitor and the switching transformer are not used to convert AC into DC, The lifetime of the LED lamp can be increased, and the LED driving device can be made compact and lightweight.

According to the present invention, the LED driving circuit can be used for both 220 V and 110 V, which are commercial AC powers, through a simple switching operation, and the LED light emitting portion can be easily expanded.

1 is a block diagram of an LED driving apparatus according to a preferred embodiment of the present invention;
2 is a circuit configuration diagram of an OP amplifier type LED driver circuit according to a first preferred embodiment of the present invention;
FIG. 3 (a) is a graph showing the current waveform of the AC voltage, and FIG. 3 (b) is a graph showing the current waveform of the rectified voltage through the rectifier circuit.
4 is a conceptual diagram illustrating a circuit configuration of a light emitting unit in which a plurality of LED devices are connected in series according to a preferred embodiment of the present invention.
5 is a circuit configuration diagram of a transistor-type LED driver circuit according to a second preferred embodiment of the present invention.
6 is a circuit configuration diagram of a MOSFET-type LED driver circuit according to a third preferred embodiment of the present invention;
FIG. 7 is a circuit configuration diagram of an OP amp common two-circuit type LED driver circuit in which LED drivers are arranged in parallel according to a fourth preferred embodiment of the present invention; FIG.
8 is a circuit configuration diagram schematically showing a circuit configuration of a conventional SMPS.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood by those skilled in the art that these embodiments are only for describing the present invention more specifically and that the scope of the present invention is not limited by these embodiments.

 1 is a block diagram schematically showing a configuration of an LED driving circuit according to a preferred embodiment of the present invention.

1, an LED driving circuit according to an embodiment of the present invention includes a power supply 10, a rectifier 20, a current converter 30, a power supply 40, a current controller 50, A control unit 60, an output delay unit 70, and a light emitting unit 80 including one or more LEDs.

 The power supply unit 10 is a device for supplying power to the LED driving circuit, and uses a commercial AC voltage such as 220 V or 110 V as a power source.

The rectifying unit 20 rectifies the AC power applied from the power supply unit 10 to generate a DC voltage and supplies the generated DC voltage to the current converting unit 30, the power supply unit 40, and the light emitting unit 80.

The current converting unit 30 applies the DC voltage supplied from the rectifying unit 20 to the current supplying unit 40 through a different path according to the magnitude of the commercial AC voltage. The present invention can use an LED driving circuit for both commercial power supplies of 110 V and 220 V through the current converting unit 30. [

The power supply unit 40 may be implemented as an amplifier, a p-type transistor, or a MOSFET as a current source that amplifies a voltage or current applied from the current conversion unit 30 and supplies a current necessary for driving the light emitting unit 80. In addition, the power supply unit includes one or more resistors to control the input voltage or current to constitute a bias circuit.

The current control unit 50 detects the overcurrent and the fluctuating current from the current supplied from the power supply unit 40 and adjusts the current supplied to the output control unit 50.

The output control unit 60 controls an output current flowing through the light emitting unit composed of one or more LED lamps and amplifies the current supplied from the power supply unit 40 to flow through the light emitting unit 80, ).

The output delay unit 70 receives a DC voltage rectified by the rectification unit 20 and includes a transistor and at least one resistor and delays the current from the power supply unit 40 to the light emitting unit 60. Accordingly, the current flowing in the light emitting unit 80 is slowly raised for a predetermined time, thereby preventing shocks from occurring in the light emitting diode due to a sudden increase in power at the beginning of the driving.

2 is a configuration diagram showing an LED driving circuit according to the first embodiment of the present invention.

As shown in FIG. 2, the LED driving circuit according to the first embodiment of the present invention uses an amplifier-type (OP amp) current source as a power supply unit.

The rectification section 20 includes a bridge circuit composed of four diodes and a resistor R1. The bridge circuit is connected to both ends of the power supply section 10, and the resistor R1 and the p-type transistor Q3 are connected in series between the + terminal and the ground of the bridge circuit at the connection point P1, The emitter of the transistor Q3 is grounded. A resistor R3 is connected to the connection point P2 and one end of the resistor R3 is connected to the base of the transistor Q3 through the resistor R2.

The current converting section 30 is composed of a switch 32 and resistors R4, R5, R6 and R7. The switch 32 of the current converting section 30 is connected at one end to a connection point P3 between the resistor R3 and the resistor R2 and the other end is selectively connected to the resistor R4 or the resistor R6, And R5 and the resistors R6 and R7 are connected in series and are disposed between the switch 32 and the ground and the connection point P4 and the resistor R6 of the resistor R4 and the resistor R5 and the resistor R6 The connection point P7 is shorted to the line. The point P8 on the line is connected to the positive terminal of the amplifier AMP, and the voltage of the connection point P8 is applied to the positive terminal of the amplifier AMP.

The power supply unit 40 includes an amplifier AMP, a resistor R11 connected between the output of the amplifier and the + input terminal of the amplifier, a resistor R11 connected between the output of the amplifier and the input terminal of the amplifier R8 and a resistor R12 connected to the output of the amplifier. The amplifier AMP is an operational amplifier and has two differential inputs (+, -) and one output terminal, and the + input terminal of the amplifier AMP is connected to the connection point P8 in the current conversion section 30.

The + input terminal and the output terminal of the amplifier AMP are connected by a resistor R11 to form a bias circuit, and the negative input terminal of the amplifier AMP is connected to the input terminal of the amplifier AMP through a resistor R8 Terminal to form a negative feedback circuit.

The current control unit 50 includes a resistor R9 and a p-type transistor Q2. The current control unit 50 includes a resistor R9 and a p-type transistor Q2 connected in series between the output terminal of the amplifier AMP and the ground and one end of the resistor R9 connected to the collector of the p- And the emitter of the p-type transistor Q2 is grounded. The base of the p-type transistor Q2 is connected to the collector by a disconnection. A capacitor C1, a diode ZD and a resistor R16 are connected between the base of the p-type transistor Q2 and the ground, do.

The output controller 60 includes a MOSFET transistor Q1 and a resistor R10. The drain of the MOSFET transistor Q1 is connected to the light emitting portion 80 and the gate thereof is connected to the output terminal of the amplifier AMP through the transistor Q5 and the resistor R12. The source of the MOSFET transistor Q1 is grounded via a resistor R10. The output controller 60 can adjust the power supplied to the light emitting unit 80 by adjusting the resistor R10.

The output delay unit 70 includes resistors R13, R14 and R15 and a p-type transistor Q4. The resistors R13 and R14 are connected in series to the connection point P6 between the rectifying section 20 and the light emitting section 80 and the connection point P13 between the resistors R13 and R14 is connected to the base of the p- And one terminal of the resistor R14 is grounded. The collector of the p-type transistor Q4 is connected to the connection point P5 between the rectification part 20 and the light emitting part 80. The emitter of the p-type transistor Q4 is connected to the output of the amplifier AMP through the resistor R15 Terminal and the resistor R11.

The light emitting unit 80 is a device to which a plurality of LEDs are connected and a forward diode D1 is connected between the rectifying unit 20 and the light emitting unit 80 to prevent reverse flow of current flowing through the light emitting unit. 4, which illustrates a circuit configuration of a light emitting unit in which a plurality of LED devices are connected in series according to a preferred embodiment of the present invention, a current supplied from an LED driving circuit flows through a plurality of LEDs connected in series, Thereby causing the light emitting portion 80 to emit light.

The operation of the amplifier type LED driving circuit according to the first embodiment of the present invention will now be described. First, the AC voltage input from the power supply unit 10 is rectified to a DC voltage by the rectifying unit 20 and connected to the connection points P1, P2, P5, And is applied to the light emitting portion 80.

Referring to Fig. 3, the AC power supply provided from the power supply unit 10 has the waveform shown in Fig. 3 (a). When this AC power source passes through the bridge circuit of the rectifying section 20, it is rectified to the waveform shown in FIG. 3 (b), and the AC power source is rectified to the DC voltage by the resistor R1 of the rectifying section 20.

 When a DC voltage is applied to the connection points P1 and P2, a current flows through R3 and R2, and a voltage is applied to the base end of the transistor Q3 to turn on the transistor Q3. Assuming that the voltage applied through the connection point P2 is Va and the voltage at the connection point P3 is Vb when the transistor Q3 is on, Vb is the voltage division value of the resistors R3 and R2. That is, the voltage Vb is expressed by the following equation (1).

… (수학식 1)

... (1)

The voltage Vb is applied to the switch 32 in the current switching unit 30 and the switch 32 is connected to either the resistor R4 or the resistor R6 depending on whether the voltage is a value of a commercial power source, And the current flows. For example, when the power input from the power source is 110V and the switch 32 is connected to the resistor R4, the current flows through the resistors R4, R5 and R7, and the voltage Vc at the connection point P8 flows through the resistors R4, As shown in FIG. Accordingly, the voltage Vc applied to the + terminal of the amplifier is expressed by the following equation (2).

… (수학식 2)

... (2)

Here, R5 // R7 is the equivalent resistance of the parallel connection of R5 and R7, and has the following relationship.

… (수학식 3)

... (3)

On the other hand, when the power input from the power supply unit is 220V and the switch 32 is connected to the resistor R6, the voltage Vc at the connection point P8 becomes a voltage distribution value of the resistors R5, R6 and R7. Therefore, the voltage Vc 'applied to the + terminal of the amplifier is expressed by the following equation (4).

… (수학식 4)

... (4)

Here, R5 // R7 represents the equivalent resistance of the parallel connection of R5 and R7.

Referring to the above equations (2) and (4), the voltage is twice as large as the case of 110V when the input power is 220V.

… (수학식 5)

... (5)

Referring to Equations (2) to (5), the LED driving circuit of the present invention is designed so that the same voltage is applied to the input terminal of the amplifier AMP in order to use the circuit elements without changing the circuit elements for both 110V and 220V . Therefore, Vc must be equal to Vc ', and R4, R5, R6, and R6 that satisfy the following equation (6) are selected and used.

… (수학식 6)

... (6)

A part of the output of the amplifier AMP is applied to the p-type transistor Q5 through the resistor R12 connected to the amplifier output terminal and at the same time is fed back through the resistor R8 to the negative input terminal of the amplifier AMP, Is fed back to the positive input terminal through the resistor R11.

When the p-type transistor Q5 to which the current is applied through the amplifier AMP is turned on, a current flows from the collector of the p-type transistor Q5 to the current control section 50 through the resistor R17 via the emitter . Accordingly, the MOSFET Q1 whose gate is connected to the collector of the transistor Q5 is also turned on by the voltage of the transistor Q5, and current flows from the collector to the emitter via the emitter. The current passing through the emitter flows to the ground through the resistor R10 and the following current also flows in the light emitting portion 80 so that a large number of LEDs included in the light emitting portion 80 emit light.

… (수학식 7)

... (7)

Therefore, the current flowing through the LED of the light emitting portion 80 can be simply controlled linearly by changing the size of the resistor R10.

On the other hand, when the voltage Va is applied to the connection points P5 and P6 from the power supply section 10 via the rectifying section 20, current flows through the resistors R13 and R14 and the difference between the base and emitter voltages of the p- If the threshold voltage is larger than the transistor driving threshold voltage, the p-type transistor Q4 is turned on. When the p-type transistor Q4 is turned on, the current delayed by the characteristics of the transistor included in the output delay unit 70 flows through the collector of the p-type transistor Q4 via the emitter, To the output terminal of the amplifier AMP at the connection point P11 and to the positive input terminal of the amplifier AMP through the resistor R11.

By the operation of the output delay unit 70, the current supplied to the light emitting unit can be gradually increased for a predetermined period of time at the beginning of driving the LED driving circuit. Therefore, shocks can be prevented from occurring in the plurality of LED elements constituting the light emitting portion through the output delay portion 70, so that smooth lighting can be performed, and the glare of the light emitting diode can be prevented.

4 is a circuit configuration diagram of an LED driving circuit according to a second preferred embodiment of the present invention.

The transistor type LED driver circuit according to the second embodiment of the present invention is different from the amplifier type LED driver circuit according to the first embodiment in that the transistor Q2 is used as the power supply unit 40, The current control unit 50, the output delay unit 70 and the light emitting unit 80 are the same except for the power supply unit 10, the rectification unit 20, the current conversion unit 30, the current control unit 50, Therefore, the description of the overlapping components will be omitted below, and the difference will be mainly described.

As shown in FIG. 4, the power supply unit of the transistor-type LED driving circuit according to the second embodiment of the present invention includes a p-type transistor Q4 and a resistor R11. The base of the p-type transistor Q4 is connected to the connection point P7 in the current conversion unit 30 and the collector is connected to the resistor R15 of the output delay unit 70. The base and collector are connected to the resistor R11 And controls the voltage input to the base of the p-type transistor Q4. The emitter of the p-type transistor Q4 is connected to the resistor R9 of the current control unit 50 and to the base of the p-type transistor Q1 of the output control unit.

The current control unit 50 includes a resistor R9 and a p-type transistor Q2. The current control unit 50 includes a resistor R9 and a p-type transistor Q2 connected in series between the output terminal of the amplifier AMP and the ground and one end of the resistor R9 connected to the collector of the p- And the emitter of transistor Q2 is grounded. The base of the p-type transistor Q2 is connected to the collector by a disconnection. A capacitor C1, a diode ZD and a resistor R16 are connected between the base of the p-type transistor Q2 and the ground, do.

The output controller 60 includes a p-type transistor Q6 and a resistor R10. The collector of the p-type transistor Q1 is connected to the light emitting portion 80 composed of a plurality of LEDs, and the emitter is grounded via the resistor R10.

The output delay unit 70 includes resistors R13, R14 and R15 and a p-type transistor Q4. The resistors R13 and R14 are connected in series to the connection point P6 between the rectifying section 20 and the light emitting section 80 and the connection point P13 between the resistors R13 and R14 is connected to the base of the p- And one terminal of the resistor R14 is grounded. The collector of the p-type transistor Q4 is connected to the connection point P5 between the rectification part 20 and the light emitting part 80. The emitter of the p-type transistor Q4 is connected to the resistor R15, Type transistor Q5 of the power supply unit 40 to the connection point P11 between the resistor R11 and the collector of the p-type transistor Q5.

The light emitting unit 80 includes a plurality of LEDs connected in series and a forward diode D1 is connected between the rectifying unit 20 and the light emitting unit 80 to prevent reverse current flow through the light emitting unit.

The operation of the transistor type LED driver circuit according to the second embodiment of the present invention will be described. First, the AC voltage input from the power supply section 10 is rectified to a DC voltage in the rectification section 20 and is supplied to the current conversion section 30, (70) and the light emitting portion (80).

A current flows from the voltage across the connection point P2 through the resistor R3 and the current flows from one of the resistors R4 and R5 or one of the resistors R6 and R7 according to the connection point of the switch 32 of the current conversion unit 30. [ Path, and some current is applied to the base of the p-type transistor Q5 of the power supply unit 40. [ When the p-type transistor Q5 to which the current is applied is turned on, a part of the current amplified by the collector of the p-type transistor Q5 via the emitter flows through the resistor R9 of the current control section 50 to the transistor Q2 And a part of the current amplified in the collector of the p-type transistor Q5 via the emitter is applied to the base of the transistor Q6 of the output control unit 60. [ Accordingly, when the p-type transistor Q6 is turned on, a current flows from the collector of the p-type transistor Q6 to the emitter via the light emitting portion 80, and thus, in the light emitting portion 80, The light is emitted. The current flowing through the LED of this light emitting portion 80 can be simply controlled by changing the size of the resistor R10.

6 is a circuit configuration diagram of a MOSFET-type LED driver circuit according to a third preferred embodiment of the present invention.

The MOSFET type LED driving circuit according to the third embodiment of the present invention differs from the amplifier type LED driving circuit according to the first embodiment in that the MOSFET Q7 is used as the power supply part and only the power supply part 10, 20, the current converting unit 30, the current controlling unit 50, the output delay unit 70, and the light emitting unit 80 are basically the same as the amplifier type LED driving circuit. Therefore, the description of the overlapping components will be omitted below, and the difference will be mainly described.

As shown in FIG. 6, the power supply unit of the MOSFET-type LED driver circuit according to the third embodiment of the present invention includes a MOSFET Q7 and a resistor R15. The gate of the MOSFET Q7 is connected to the connection point P7 in the current converting portion 30 and the drain is connected to the resistor R15 of the output delay portion 70. The gate and the drain of the MOSFET Q7 are connected by a resistor R11 And controls the voltage input to the gate. The source of the MOSFET Q7 is connected to the resistor R9 of the current control unit 50 at the connection point P11 and to the gate of the MOSFET Q1 of the output control unit.

The current control unit 50 includes a resistor R9 and a p-type transistor Q2. The current control unit 50 includes a resistor R9 and a p-type transistor Q2 connected in series between the output terminal of the amplifier AMP and the ground and one end of the resistor R9 connected to the collector of the p- And the emitter of transistor Q2 is grounded. The base of the p-type transistor Q2 is connected to the collector by a disconnection. A capacitor C1, a diode ZD and a resistor R16 are connected between the base of the p-type transistor Q2 and the ground, do.

The output control unit 60 includes a MOSFET Q1 and a resistor R10. The drain of the MOSFET Q1 is connected to the light emitting portion 80 composed of a plurality of LEDs, and the source is grounded via the resistor R10.

The output delay unit 70 includes resistors R13, R14 and R15 and a p-type transistor Q4. The resistors R13 and R14 are connected in series at a connection point P6 between the rectification part 20 and the light emitting part 80 and the connection point between the resistor R13 and the resistor R14 is connected to the base of the p- , And one terminal of the resistor R14 is grounded. The collector of the p-type transistor Q4 is connected to the connection point P5 between the rectification part 20 and the light emitting part 80. The emitter of the p-type transistor Q4 is connected to the resistor R15, To the node P11 between the drain of the MOSFET Q7 of the power supply unit 40 and the resistor R11.

The light emitting unit 80 includes a plurality of LEDs connected in series and a forward diode D1 is connected between the rectifying unit 20 and the light emitting unit 80 to prevent reverse current flow through the light emitting unit.

In the operation of the MOSFET type LED driver circuit, when an AC voltage is applied from the power supply portion to the LED driver circuit, the rectified current is rectified by the rectifier portion, and the rectified DC voltage is applied to the LED lighting portion 60.

The operation of the MOSFET type LED driving circuit according to the third embodiment of the present invention will now be described. First, the AC voltage input from the power supply unit 10 is rectified to a DC voltage in the rectifying unit 20 and connected to the connection points P1, P2, P5, And is applied to the light emitting portion 80.

A current flows from the voltage applied to the connection point P2 through the resistor R3 and the signal path of one of the resistors R4 and R5 or the resistors R6 and R7 is changed in accordance with the connection point of the switch 32 of the current transformer 30 And the voltage Vc across both ends of the resistors R5 and R7 is applied to the gate of the MOSFET Q7 of the power supply unit 40. [ When the MOSFET Q7 is turned on at the applied voltage, a part of the current amplified via the source at the drain of the MOSFET Q7 flows through the resistor R9 of the current control part 50 to the collector of the transistor Q2 and to the base A part of the amplified current is supplied to the MOSFET Q1 of the output control unit 60. [ When the MOSFET Q1 is turned on by the voltage at the connection point between the emitter of the transistor Q7 and the resistor R9 of the current control unit 50, So that a large number of LEDs emit light in the light emitting unit 80. The current flowing through the LED of this light emitting portion 80 can be simply controlled by changing the size of the resistor R10.

7 is a circuit configuration diagram of an OP amp common two-circuit type LED driver circuit in which LED drivers are arranged in parallel according to a fourth embodiment of the present invention.

 The OP amplifier common two-circuit type LED driver circuit according to the fourth embodiment of the present invention includes a power supply section 10, a rectification section 20 for rectifying the AC voltage supplied from the power supply section 10, A first power supply unit 40 including a first amplifier AMP for receiving a positive terminal voltage from the current converting unit 30 and providing an amplified voltage, A first current control unit 50 for receiving the current amplified from the power supply unit 40 and for limiting the current to transmit the amplified current to the first current control unit 50 and a current control unit 50 for receiving the current from the first current control unit 50, A first output delay unit 70 for slowly raising the current flowing through the first light emitting unit 80 for a predetermined period of time to prevent the occurrence of shock of the LED at the initial stage of driving, (AMP '), receives the + terminal voltage from the current converting unit 30, A second current control unit 50 'for receiving the amplified current from the second power supply unit 40' to limit the current to the current, and a second current control unit 50 ' A second output control part 60 'for receiving a current from the second light emitting part 80' and controlling the current so that a constant current flows through the second light emitting part 80 ' And a second output delay unit 70 'for slowly rising to prevent the shock of the LED.

As described above, according to the present invention, by implementing the circuit for driving the first light emitting unit and the second light emitting unit by respectively adding the power supply units at the connection point P7 of the current switching unit, two or more light emitting units can be separated The power required for the light emitting unit can be appropriately adjusted and used, and the light emitting unit can be freely extended.

The transistor of the present invention can be implemented not only as a p-type transistor but also as an n-type transistor, and the resistor can be implemented as an active element as well as a passive element.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention. Therefore, the technical scope of the present invention should not be limited to the described embodiments, but should be determined by the scope of the claims as well as the following claims.

10: power supply
20:
30: current conversion unit
40: Power source
50:
60:
70: Output delay unit
80: light emitting unit

Claims (15)

A rectifying unit for rectifying the AC voltage supplied from the commercial AC voltage to a DC voltage;
A power supply unit for supplying a current so that a constant current flows through the at least one LED;
A current switching unit for applying the DC voltage provided by the rectifying unit to the power supply unit at a constant voltage regardless of the magnitude of the commercial AC voltage;
An output control unit for controlling a current supplied from the power supply unit to the LED so that a constant current flows through the LED;
A current controller for detecting an overcurrent and a fluctuating current from a current supplied from the power supply unit and controlling a current supplied to the output controller; And
And an output delay unit configured to receive the DC voltage rectified by the rectifier and delay the current transferred from the power supply unit to the LED. The method of claim 1,
The power supply unit is an amplifier-type current source and includes a + input terminal connected to the current switching unit, an output terminal connected to the resistor R12, a negative input terminal connected to the output terminal through a resistor R8 to form a negative feedback circuit Comprising an amplifier configured,
The output delay unit includes a transistor Q4 and a resistor R15 between the rectifier and the LED, and a series connection structure of a resistor R13 and a resistor R14 connected between a connection point between the rectifier and the LED and ground. The collector of the transistor Q4 is connected to the rectifier, the emitter is connected to the resistor R15, the base is connected to the connection point of the resistor R17 and the resistor R18, and the resistor R15. Is connected to the output terminal of the amplifier to provide a delayed current to the power supply,
The current control unit includes a resistor R9 and a p-type transistor Q2 between the output terminal of the power supply unit and the ground, a collector of the p-type transistor Q2 is connected to the resistor R9, An output terminal of the power supply unit, the emitter is grounded,
The output control unit includes a MOSFET Q1 and a resistor R10 between the LED and the ground and the gate of the MOSFET Q1 is connected to the output of the amplifier AMP through a collector and a resistor R12 of a p- ), And the source of the MOSFET (Q1) is grounded via a resistor (R10), and the current flowing through the LED is controlled by a resistor (R10). The method of claim 1,
The power supply includes a p-type transistor (Q5) having a base connected to the current switching unit, a collector connected to the base through a resistor (R11), and an emitter connected to the current control unit,
The output delay unit includes a transistor Q4 and a resistor R15 between the rectifier and the LED, and a series connection structure of a resistor R13 and a resistor R14 connected between a connection point between the rectifier and the LED and ground. The collector of the transistor Q4 is connected to the rectifier, the emitter is connected to the resistor R15, the base is connected to the connection point of the resistor R17 and the resistor R18, and the resistor R15. Is connected to the collector of transistor Q5 to provide a delayed current to the power supply,
The current control unit includes a resistor R9 and a p-type transistor Q2 between the emitter and the ground of the power supply unit. The collector of the p-type transistor Q2 is connected to the resistor R9, An output terminal of the power supply unit, the emitter is grounded,
The output control unit includes a p-type transistor Q6 and a resistor R10 between the LED and the ground, the base of the p-type transistor Q6 is connected to the emitter of the power supply unit 40, Wherein the emitter is connected to the LED and the emitter is grounded via a resistor R10 and controls a current flowing in the LED by a resistor R10. The method of claim 1,
Wherein the power supply portion includes a MOSFET (Q7) having a gate connected to the current switching portion, a drain connected to the gate via a resistor (R11), and a source connected to the current control portion,
The output delay unit includes a transistor Q4 and a resistor R15 between the rectifier and the LED, and a series connection structure of a resistor R13 and a resistor R14 connected between a connection point between the rectifier and the LED and ground. The collector of the transistor Q4 is connected to the rectifier, the emitter is connected to the resistor R15, the base is connected to the connection point of the resistor R17 and the resistor R18, and the resistor R15. Is connected to the drain of the MOSFET Q7 to provide a delayed current to the power supply,
The current control unit includes a resistor R9 and a p-type transistor Q2 between the source and the ground of the power supply unit. The collector of the p-type transistor Q2 is connected to the resistor R9, Connected to the output terminal of the supply section, the emitter is grounded,
The output control unit includes a MOSFET Q1 and a resistor R10 between the LED and the ground, the gate of the MOSFET Q1 is connected to the source of the power supply unit 40, the drain is connected to the LED , The source is grounded via a resistor (R10), and the current flowing through the LED is controlled by a resistor (R10). The method according to any one of claims 1 to 4,
Wherein the current switching unit includes a switch for transmitting a current to the power supply unit in a different path depending on a magnitude of a commercial AC voltage. The method of claim 5, wherein
Wherein the current switching unit includes a resistor R4 and a resistor R5 connected in series between the switch and ground and a resistor R6 and a resistor R7 connected in series between the switch and ground, Connected to one of the resistor (R4) and the resistor (R6)
A connection point between the resistor R4 and the resistor R5 and a connection point between the resistor R6 and the resistor R7 are connected by a line and the power supply unit is connected to the line, And an LED driving circuit for driving the LED driving circuit. The method according to any one of claims 1 to 4,
And a forward diode (D1) for preventing reverse flow of current to the LED is connected between the rectifying part and the LED. The method according to any one of claims 1 to 4,
Wherein a capacitor (C1), a diode, and a resistor (R14) are connected between a base of the transistor (Q2) of the current control unit and the ground. The method according to any one of claims 1 to 4,
Wherein the rectifying section includes a bridge circuit composed of four diodes and a resistor. The method according to any one of claims 1 to 4,
Wherein the power supply comprises a first power supply supplying current to a first LED comprising one or more LEDs and a second power supply supplying current to a second LED comprising one or more LEDs,
The output control unit includes a first output control unit for controlling the current supplied to the first LED and a second output control unit for controlling the current supplied to the second LED,
Wherein the current control unit includes a first current control unit for controlling a current supplied to the first output control unit and a second current control unit for controlling a current supplied to the second output control unit,
The output delay unit includes a first output delay unit delaying the current delivered to the first LED from the first power supply unit and a second output delay unit delaying the current delivered from the second power supply unit to the second LED And an LED driving circuit for driving the LED driving circuit. 11. The method of claim 10,
Wherein the current switching section includes a switch for transmitting a current to the first and second power supply sections in a different path depending on the magnitude of the commercial AC voltage. The method of claim 11,
Wherein the current switching unit includes a resistor R4 and a resistor R5 connected in series between the switch and ground and a resistor R6 and a resistor R7 connected in series between the switch and ground, Connected to one of the resistor (R4) and the resistor (R6)
A connection point between the resistor R4 and the resistor R5 and a connection point between the resistor R6 and the resistor R7 are connected by a line and the first and second power supply units are respectively connected to the power supply unit Current or voltage is applied to the LED driving circuit. The method of claim 11,
A first forward diode (D1) is connected between the rectifying part and the first LED to prevent reverse current of the current to the first LED, and between the rectifying part and the second LED, , And a second forward diode (D1) for the second forward diode (D1) is connected. The method of claim 11,
Wherein a capacitor (C1), a diode, and a resistor (R14) are connected between a base of the transistor (Q2) of each of the first and second current control portions and the ground. The method of claim 11,
Wherein the rectifying section includes a bridge circuit composed of four diodes and a resistor.

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