WO2016047964A1

WO2016047964A1 - Alternating-current led drive circuit

Info

Publication number: WO2016047964A1
Application number: PCT/KR2015/009759
Authority: WO
Inventors: 조홍수; 신소봉
Original assignee: 메를로랩 주식회사
Priority date: 2014-09-24
Filing date: 2015-09-17
Publication date: 2016-03-31
Also published as: KR20160035780A; KR101626360B1

Abstract

The present invention relates to an alternating-current LED drive circuit which can significantly improve flicker-free characteristics and at the same time implement a high power factor and a stable dimming function through the constant normal operation of a dimmer.

Description

AC LED Drive Circuit

An embodiment of the present invention relates to an AC LED driving circuit. For example, flicker free characteristics are greatly improved and a high power factor is realized, while stable dimming function is always possible through normal operation of the dimmer. The present invention relates to an AC LED driving circuit.

AC LED driving circuit proposed to drive LED under AC power has advantages of simple manufacturing process, low defect rate and long life compared with Switched mode power supply (SMPS) method.

Referring to Figure 1, Figure 1 is a view showing a conventional general AC LED driving circuit, the AC LED driving circuit is a basic principle to sequentially control the current source, high efficiency and long life and reliability and reduction of the size of LED lighting, etc. It has several advantages.

Meanwhile, the AC LED driving circuit has a weak point in terms of flicker generation, and the present applicant has proposed Korean Patent No. 1414902 (name: “AC LED Driving Circuit”).

FIG. 2 conceptually shows such an “AC LED driving circuit”. As shown in FIG. 2, when the LED is insufficient when the LED is driven, an insufficient voltage is supplied from the voltage charger to eliminate the light off phenomenon and thereby flicker. Improve properties. Power factor characteristics are also improved by the switch control function, which allows the voltage charger to maintain a fixed current value even beyond the peak of the supply voltage.

In detail, the AC LED driving circuit according to FIG. 2 eliminates the flicker phenomenon and improves the power factor as described above. Another function of LED lighting is dimming (hereinafter, the term “dimming”) is used. It was relatively weak in terms of

Applicant has applied for an additional independent current path (I_HOLD) for driving a dimmer for dimming in a typical AC LED driving circuit through Korean Patent No. 1357916 (name of the invention: “Dimming system of lighting device using light emitting element”). We propose a method of forming).

Figure 3 shows the AC LED driving circuit of the dimming system of the lighting device using such a light emitting device.

In addition, a technique for applying the proposed dimming method to Korean Patent No. 11414902 of the present applicant is not currently provided, and thus, a situation is required.

In other words, the general AC LED driving circuit is a method of controlling the current source according to the magnitude of the voltage by simply driving the dimmer by the conventional dimming method. Therefore, the brightness of the light naturally occurs according to the waveform of the input voltage changed through the dimmer. This allows for instant dimming.

In contrast, since the AC LED driving circuit according to FIG. 2 maintains a constant current regardless of the magnitude of the voltage, in order to implement a dimming function, a function of changing the amount of LED current according to a dimming angle is provided. Required.

An embodiment of the present invention provides an AC LED driving circuit capable of implementing a stable dimming function through the normal operation of the dimmer while the flicker free characteristic is greatly improved and a high power factor is realized.

An AC LED driving circuit according to an embodiment of the present invention includes a power supply including a dimmer receiving an AC voltage of an AC power source and a rectifying circuit for the output voltage of the dimmer, an LED lighting unit connected to an output terminal of the rectifying circuit; And a current channel switching unit connected to an output terminal of the LED lighting unit to form a current supply channel of the LED lighting unit, and connected in parallel to a connection line between the power supply unit and the LED lighting unit to charge voltage from the power supply unit and to the LED lighting unit. A voltage driver configured to selectively supply a charging voltage to the LED lighting unit having a switching function for the LED lighting unit, and a LED driving unit including a charging voltage switching control unit to control a switching function of the voltage charging unit, between the rectifying circuit and an input terminal of the LED lighting unit. An input terminal at a connection line between a connection line and an output end of the LED lighting unit and the rectifier circuit A voltage controlled current source (VCCS) to which the output terminals are respectively connected, a common resistor commonly connected to an output line of the voltage controlled current source and a connection line between the output terminal of the LED lighting unit and the rectifier circuit, and the voltage controlled current source A reference voltage supply unit connected in parallel on a connection line including the common resistor between the output terminal of the output terminal and the rectifier circuit and applying a positive reference voltage to the voltage controlled current source, the voltage controlled current source connected in series with the common resistor. An output voltage is input to a negative voltage of the voltage controlled current source, and a current supplied to the LED driver from the rectifier circuit is included in a negative feedback path, and a connection line between the output terminal of the rectifier circuit and the dimmer driver. Is connected to sense the dimming angle of the voltage input to the dimmer driver Based on the value of humming angle it may include a reference voltage phase converter for generating a control voltage for the variable drive current of the LED driving unit included in the LED driving unit.

The reference voltage phase converter may convert an input signal from the rectifier circuit phase-cut in the dimmer into a pulse type signal and then convert the converted pulse into a reference voltage.

In addition, the reference voltage phase conversion unit is connected to the output terminal of the rectifier circuit pulse generator for converting the phase cut (Phase cut) input signal from the dimmer in the form of a square wave (Pulse Generator), and the output terminal of the pulse generator It may include a voltage pulse converter connected to the converter for converting the pulse signal changed in the pulse generator into a reference voltage.

The pulse generator may also include a first resistor connected to an output terminal of the rectifier circuit, a second resistor connected in series with the first resistor, and an OP amplifier in which a positive input terminal is connected in parallel between the first resistor and the second resistor. The voltage pulse converter may include a low pass filter connected to an output terminal of the OP amplifier.

The pulse generator may also include a first resistor connected to an output terminal of the rectifier circuit, a second resistor connected in series with the first resistor, and an OP amplifier in which a positive input terminal is connected in parallel between the first resistor and the second resistor. The voltage pulse converter may include an integrator connected to an output terminal of the OP amplifier and a sample and hold circuit connected to an output terminal of the integrator.

In addition, the voltage pulse converter is connected to the output terminal of the rectifier circuit generates a sampling time signal based on the output voltage output through the rectifier circuit, and generates a sampling time reference signal for controlling the sample hold circuit based on the generated signal It may further include wealth.

The voltage charging unit of the LED driver may include a capacitor connected to a connection line between the power supply unit and the LED lighting unit, and a first MOS FET installed on the connection line between the capacitor and the LED lighting unit to perform a switching function. The voltage switching controller may include a second MOS FET connected to the capacitor-side contact of the first MOS FET, a first resistor disposed on a connection line between the capacitor-side contact of the first MOS FET and the second MOS FET. An output terminal connected to a second MOS FET, and a second OP common to which a reference voltage and an output voltage of the second MOS FET are input, an output terminal of the second MOS FET, and a second common connection to the current channel switching unit. The current channel switching unit includes a resistor, and an output terminal is connected to the third MOS FET and the third MOS FET connected to the output terminal of the LED lighting unit, and a reference voltage is input to the input terminal. A second OP amplifier to which the output voltage of the third MOS FET is input, and a third resistor provided on a connection line between an output terminal of the third MOS FET and a second resistor of the charging voltage switching controller; A reference voltage VREF1 input to the first OP amplifier of the charging voltage switching controller, a reference voltage VREF2 input to the second OP amplifier of the current channel switching unit, and a second resistor and a third resistor are as follows.

The condition of may be established.

The voltage charging unit of the LED driver may include a capacitor connected to a connection line between the power supply unit and the LED lighting unit, and a first MOS FET installed on the connection line between the capacitor and the LED lighting unit to perform a switching function. The voltage switching controller may include a second MOS FET connected to the capacitor-side contact of the first MOS FET, a first resistor disposed on a connection line between the capacitor-side contact of the first MOS FET and the second MOS FET. An output terminal connected to a second MOS FET, and a second OP common to which a reference voltage and an output voltage of the second MOS FET are input, an output terminal of the second MOS FET, and a second common connection to the current channel switching unit. The current channel switching unit includes a resistor, and a third MOS FET connected to an output terminal of the LED lighting unit, an output terminal is connected to the third MOS FET, and a reference voltage is input to the input terminal. And a second OP amplifier to which the output voltage of the third MOS FET is input, respectively, wherein the reference voltage VREF1 is input to the first OP amplifier of the charging voltage switching controller and the second OP amplifier is input to the second OP amplifier of the current channel switching unit. When the condition of VREF1 < VREF2 is established between the reference voltages VREF2, and when the supply voltage value of the power supply unit is set to V1 and the voltage value necessary for the normal operation of the LED lighting unit and the current channel switching unit to VT, the first MOS FET is When V1> VT, an open state, a short state when V1 ≦ VT, and a transition to a short state when V1 = VT may be performed.

The voltage charging unit of the LED driver may include a capacitor connected to a connection line between the power supply unit and the LED lighting unit, and a first MOS FET installed on the connection line between the capacitor and the LED lighting unit to perform a switching function. The voltage switching controller may include a second MOS FET connected to the capacitor side contact of the first MOS FET, a first resistor disposed on a connection line between the second MOS FET and the capacitor side contact of the first MOS FET, An output terminal connected to a second MOS FET and commonly connected to a first OP amplifier to which a reference voltage and an output voltage of the second MOS FET are input, an output terminal of the second MOS FET, and an output terminal of the current channel switching unit, respectively; And a fourth resistor disposed on a connection line between a second resistor, the second resistor, and an output terminal of the second MOS FET, wherein the current channel switching unit is the LED lighting unit. And a second OP amplifier connected to an output terminal of the third MOS FET and an output terminal connected to the third MOS FET, wherein a reference voltage and an output voltage of the third MOS FET are respectively input to an input terminal, wherein the charging voltage switching controller The reference voltage VREF1 input to the first OP amplifier of the reference voltage VREF2 input to the second OP amplifier of the current channel switching unit and the second resistor and the fourth resistor

The condition of may be established.

The dimmer driver further includes a MOS FET in which the voltage control current source is connected to a drain line between the output terminal of the rectifier circuit and the first LED part, a source is connected to the common resistor, and a gate is connected to the reference voltage supply part. And the reference voltage supply unit includes a resistor connected to an internal supply (Iref) and an output terminal of the MOS FET, a gate of the MOS FET is connected on a connection line of the current source and the resistor, and the resistor is the common. It may be connected in parallel on the connection line between the resistor and the rectifier circuit.

The LED lighting unit may include an n-th LED lighting unit located at a longest distance from the output terminal of the rectifying circuit, starting with a first LED lighting unit located at a shortest distance from the output terminal of the rectifying circuit, and the current channel switching unit may be configured to be the first LED lighting unit To n-th LED lighting units may be individually connected to form a current supply channel for the corresponding LED lighting unit.

According to the exemplary embodiment of the present invention, the AC LED driving circuit enables a significant improvement in flicker free characteristics and a high power factor while at the same time allowing the normal operation of the dimmer at all times.

1 is a view showing a conventional general AC LED driving circuit

2 conceptually illustrates one form of a conventional AC LED drive circuit;

FIG. 3 conceptually illustrates a form different from FIG. 2 of a conventional AC LED driving circuit. FIG.

4 conceptually illustrates an AC LED driving circuit according to an embodiment of the present invention;

5 is a diagram illustrating an AC LED driving circuit to which each embodiment of the LED driving unit, the dimmer driving unit, and the reference voltage phase conversion unit is applied in the AC LED driving circuit according to an embodiment of the present invention.

6 is a diagram illustrating an embodiment of a reference voltage phase shifter in FIG. 5;

7 is a view illustrating generation of a duty signal according to a dimming angle in the AC LED driving circuit of FIG. 6;

8 and 9 illustrate reference voltages according to dimming angles in the AC LED driving circuit of FIG. 6.

FIG. 10 is a view illustrating another embodiment of a pulse generator and a voltage pulse converter of a reference voltage phase shift unit in an AC LED driving circuit according to FIG. 5; FIG.

11 and 12 illustrate another embodiment of the LED driver in the AC LED driver circuit according to FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION The following detailed description of the invention refers to embodiments in which the invention may be practiced and to the accompanying drawings, which are shown by way of illustration of the embodiments. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It is to be understood that the various embodiments of the invention are different, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention with respect to one embodiment. It is also to be understood that the location or arrangement of individual components within each disclosed embodiment may be changed without departing from the spirit and scope of the invention.

The following detailed description, therefore, is not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. Like reference numerals in the drawings refer to the same or similar functions throughout the several aspects.

The terms used in the present invention have been selected as widely used general terms as possible in consideration of the functions in the present invention, but this may vary according to the intention or precedent of the person skilled in the art, the emergence of new technologies and the like. In addition, in certain cases, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the corresponding description of the invention. Therefore, the terms used in the present invention should be defined based on the meanings of the terms and the contents throughout the present invention, rather than the names of the simple terms.

When a part of the specification is said to "include" any component, this means that it may further include other components, except to exclude other components, unless specifically stated otherwise. In addition, the terms "... unit", "... module" described in the specification means a unit for processing at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. Can be.

An AC LED driving circuit according to an embodiment of the present invention will be described with reference to FIGS. 4 to 12.

4 is a view conceptually illustrating an AC LED driving circuit according to an embodiment of the present invention.

As shown, the AC LED driving circuit 100 according to an embodiment of the present invention includes a power supply 110, LED driver 120, dimmer driver 130, reference voltage phase conversion unit 140 It is composed.

The power supply unit 110 includes a dimmer 111 that receives an AC voltage from an external AC power source and a rectifier circuit 112 for an output voltage of the dimmer 111. Here, any one kind of a conventional phase-cut scheme may be selected and used as the dimmer 111, and thus, a detailed description and illustration of the dimmer 111 will be omitted in the present embodiment. In addition, the rectifier circuit 112 may be a conventional bridge circuit, so the detailed description and illustration of the rectifier circuit 112 in the present embodiment is omitted.

The LED driver 120 includes an LED lighting unit 121, a current channel switching unit 122, a voltage charging unit 123, and a charging voltage switching control unit 124.

The LED lighting unit 121 is connected to the output terminal of the rectifier circuit 112 of the power supply unit 110, but the figure illustrates the form in which the LED lighting unit 121 is formed of one LED, but this is for convenience of illustration. In addition, the LED lighting unit 121 may be formed to include a plurality of LEDs. In detail, the LED lighting unit 121 may include an n-th LED unit located at the longest distance from the first LED unit located at the shortest distance with respect to the output terminal of the rectifier circuit 112. In addition, the plurality of LED units included in the LED lighting unit 121 may be sequentially connected in series from the first LED unit to the nth LED unit, and individual LEDs included in each LED unit may be sequentially connected in series. In addition, each LED unit may be formed of one LED or two or more LEDs may be formed in a group unit.

The current channel switching unit 122 is connected to the output terminal of the LED lighting unit 121 to form a current supply channel for the LED lighting unit 121. In this embodiment, since the LED lighting unit 121 has a single configuration, the current channel switching unit 122 has a single configuration, but as described above, since the LED lighting unit 121 may be formed in plural, the current The channel switching unit 122 may also be formed in plural and individually connected to the output terminal of each LED lighting unit to form a current supply channel for the corresponding LED lighting unit. In addition, a detailed configuration of the current channel switching unit 122 will be described later with reference to FIG. 5.

The voltage charging unit 123 is connected in parallel to the connection line between the power supply unit 110 and the LED lighting unit 121 to charge the voltage from the power supply unit 110, and the voltage charging unit 123 is switched to the LED lighting unit 121. It has a function to selectively supply the charging voltage to the LED lighting unit 121.

The charging voltage switching controller 124 controls the switching function of the voltage charging unit 123.

Next, the configuration of the dimmer driver 130 will be described.

The dimmer driver 130 may include a voltage control current source 131, a common resistor 132, and a reference voltage supply unit 133.

The voltage controlled current source VCCS is connected to an input line between the rectifier circuit 112 of the power supply 110 and the input terminal of the LED lighting unit 121, and the output terminal of the LED lighting unit 121. An output terminal is connected to the connection line between the rectifier circuits 112.

The common resistor 132 is commonly connected to the output line of the voltage control current source 131 and the connection line between the output terminal of the LED lighting unit 121 and the rectifier circuit 112.

The reference voltage supply 133 is connected in parallel on a connection line including a common resistor 132 between the output terminal of the voltage controlled current source 131 and the rectifier circuit 112, and the reference voltage supply 133 is a voltage controlled current source 131. Apply a positive reference voltage to).

That is, the reference voltage supply unit 133, the common resistor 132, and the voltage control current source 131 form the dimmer driver 130 in the form of negative feedback, that is, connected in series with the common resistor 132. The output voltage of the voltage controlled current source 131 is input to the negative voltage of the voltage controlled current source 131 so that the current supplied from the rectifier circuit 112 to the LED driver 120 is supplied to the negative feedback path of the dimmer driver 130. Therefore, the current supplied to the LED driver 120 is included in the inferior path of the dimmer driver 130, and the current value flowing through the voltage control current source 131 is included in the current value supplied to the LED driver 120. Interlocked.

In more detail, the voltage difference between the positive input terminal and the negative input terminal of the reference voltage supply unit 133 with respect to the voltage controlled current source 131 directly affects the output current value of the voltage controlled current source 131. . At this time, the output current of the voltage controlled current source 131 and the common resistor 132 R connected in series thereto are applied to the negative input terminal of the voltage controlled current source 131, and between the input voltage and the output current of the voltage controlled current source 131. A negative feedback path is formed at. When the path of the current supplied to the LED driver 120 is connected in parallel to the negative feedback path, the current supplied to the LED driver 120 is applied to the common resistor 132 R to input the voltage controlled current source 131. It has a direct effect on the voltage and also on the negative feedback circuit. And this is explained by the following three cases.

First, when the current supplied to the LED driver 120 is so large that the voltage applied to the common resistor 132 R is greater than the positive input voltage V _{REF1 of the} voltage controlled current source 131, the voltage controlled current source 131 is turned off. Accordingly, the output current of the voltage control current source 131 becomes 0 so that the current output from the rectifier circuit 112 of the power supply 110 and the current supplied to the LED driver 120 become the same value. This corresponds to a condition in which the dimmer 111 is driven by a supply current for the LED driver 120.

Second, if the current supplied to the LED driver 120 is 0, the negative part for driving the dimmer 111 depends entirely on the value of the positive input voltage V _REF1 of the voltage control current source 131 and the value of the common resistor 132 R. A feedback circuit is formed, whereby the value of the output current of the voltage controlled current source 131 is also set by the positive input voltage V _{REF1 and the} value of the common resistor 132 R of the voltage controlled current source 131. At this time, the current output from the rectifier circuit 112 of the power supply unit 110 and the output current of the voltage control current source 131 is the same value, which corresponds to the condition that the dimmer 111 is driven by the dimmer driver 130. .

Third, when the value of the current supplied to the LED driver 120 is greater than 0, but the value of V _REF1 is greater than the value of the value of the current supplied to the LED driver 120 multiplied by the common resistor 132, The negative feedback circuit for driving the dimmer 111 is driven while being organically influenced by the current supplied to the LED driver 120. That is, when the current supplied to the LED driver 120 increases, ( _VREF1 − The value of the current x common resistance supplied to the LED driver is reduced, and the output current of the voltage controlled current source 131 decreases. On the other hand, when the current supplied to the LED driver 120 decreases (V _REF1 − The value of the current x common resistance supplied to the LED driver increases, so that the output current of the voltage controlled current source 131 increases.

In summary, when the current supplied to the LED driver 120 increases, the output current of the voltage controlled current source 131 decreases, and when the current supplied to the LED driver 120 decreases, the output current of the voltage controlled current source 131 increases. Complementary forms of driving are achieved. This corresponds to a condition in which the dimmer 111 is driven by the sum of the supply current for the LED driver 120 and the output current of the voltage control current source 131 of the dimmer driver 130.

The third case may be represented by the following equation, and the following equation theorem may be derived using general circuit theory in the circuit of FIG. 4.

(V _REF1 > current x common resistance supplied to the LED driver)

The output current of the voltage controlled current source = g _m V _REF1 = g _m (V _REF1 -V _RS ) = g _m (V _REF1- (output current of the voltage controlled current source + current supplied to the LED driving unit) x common resistance).

When the value of the current supplied to the LED driver 120 is not large enough as necessary to drive the dimmer 111, the output current of the voltage controlled current source 131 is supplemented with the value of the above equation. . In addition, when the value of the current supplied to the LED driver 120 becomes 0, it indicates that the output current of the voltage controlled current source 131 is determined entirely through V _REF1 and the common resistor 132 R.

On the contrary, in the case of (V _REF1 ≤ current supplied to the LED driver) ((+) input voltage of the voltage controlled current source ≤ 0), the output current of the voltage controlled current source 131 becomes 0, and the dimmer 111 ) Is driven entirely through the current supplied to the LED driver 120. That is, this case is a case where the dimmer 111 can be sufficiently driven only by the current supplied to the LED driver 120.

In conclusion, when the current supplied to the LED driver 120 is sufficient, the dimmer 111 is driven by the current supplied to the LED driver 120, and the current supplied to the LED driver 120 drives the dimmer 111. If it is insufficient in the supplement is made through the output current of the voltage control current source 131.

Next, the reference voltage phase shifter 140 will be described.

The reference voltage phase shifter 140 is connected to a connection line between the output terminal of the rectifier circuit 112 and the dimmer driver 130, and the reference voltage phase shifter 140 dimmes the voltage input to the dimmer driver 130. After detecting a dimming angle, a control voltage for varying the driving current of the LED lighting unit 121 included in the LED driving unit 120 is generated based on the detected dimming angle value. Here, the dimming angle of the input voltage with respect to the dimmer driver detected through the reference voltage phase converter is equal to the dimming angle of the input voltage with respect to the LED driver connected in parallel with the dimmer driver with respect to the power supply.

That is, the amount of current supplied to the LED lighting unit of the LED driving unit varies according to the dimming angle of the input voltage to the dimmer driving unit detected through the reference voltage phase shifting unit, and thus the flicker free characteristic of the LED driving circuit is changed. Improvements and high power factors can be realized while the dimming function of the dimmer can always be kept stable.

Next, a specific example of an AC LED driving circuit according to an exemplary embodiment of the present invention will be described with reference to FIG. 5.

That is, FIG. 5 is a diagram illustrating an example in which each embodiment of the LED driver, the dimmer driver, and the reference voltage phase shifter is applied to an AC LED driver circuit according to an exemplary embodiment of the present invention.

Therefore, the AC LED driving circuit 200 includes a power supply unit 110, an LED driver 120, a dimmer driver 130, and a reference voltage phase shifter 140, and the LED driver except for the power supply unit 110. A detailed configuration of the 120, the dimmer driver 130, and the reference voltage phase converter 140 will be described.

The power supply unit 110 includes a dimmer 111 and a rectifier circuit 112, and the dimmer 111 and the rectifier circuit 112 may be referred to with reference to FIG. 4.

The LED driver 120 includes a charge voltage switching controller 124 including a second MOS FET 124a, a first resistor 124b, a first OP amplifier 124c, and a second resistor 124d.

The second MOS FET 124a is connected to the capacitor 123a side contact of the first MOS FET 123b of the switch function included in the voltage charging unit 123.

The first resistor 124b is provided on a connection line between the capacitor 123a side contact of the first MOS FET 123b and the second MOS FET 124a.

An output terminal of the first OP amplifier 124c is connected to the second MOS FET 124a, and a reference voltage and an output voltage of the second MOS FET 124a are respectively input to the input terminal of the first OP amplifier 124c.

The second resistor 124d is commonly connected to the output terminal of the second MOS FET 124a and the current channel switching unit 122.

The current channel switching unit 122 has a third MOS FET 122a connected to the output terminal of the LED lighting unit 120 and an output terminal is connected to the third MOS FET 122a of the current channel switching unit 122. And a second OP amplifier 122b to which a reference voltage and an output voltage of the third MOS FET 122a are respectively input.

At this time, VREF1 < VREF2 between the reference voltage VREF1 input to the first OP amplifier 124c of the charging voltage switching controller 124 and the reference voltage VREF2 input to the second OP amplifier 122b of the current channel switching unit 122. Conditions must be established.

And a diode is installed on the connection line between the power supply unit 110 and the capacitor 123a and the connection line between the power supply unit 110 and the LED lighting unit 120, respectively.

With this configuration, the second OP amplifier 122b and the third MOS FET 122a of the current channel switching unit 122 form a main current source. When the voltage V1 is lower than the voltage VT required for driving the main current source and the LED lighting unit 120, the first resistor 124b and the first OP amplifier 124c of the charging voltage switching control unit 124 are charged by the charging voltage of the voltage V2. ), An auxiliary current source formed of the second MOS FET 124a and the second resistor 124d is driven to generate a voltage difference value between the source-gate of the third MOS FET 122a of the current channel switching unit 122. . When the voltage difference between the source and gate of the third channel MOS FET 122a of the current channel switch 122 is greater than the threshold voltage of the third MOS FET 122a of the current channel switch 122, the voltage charger 123 The voltage charged in the capacitor 123a is applied to the LED lighting unit 120 and the current channel switching unit 122 to supply the voltage necessary for the main current source. That is, the first MOS FET is in an open state when V1> VT, a short state when V1 ≦ VT, and a transition to a short state when V1 = VT.

The reference voltage VREF1 input to the first OP amplifier 124c of the charging voltage switching controller 124 and the reference voltage VREF2 input to the second OP amplifier 122b of the current channel switching unit 122 for the series of operations. However, the condition of VREF1 < VREF2 must be established.

In the dimmer driver 130, the voltage control current source 131 includes a fourth MOS FET 131a and a third OP amplifier 131b. That is, the third OP amplifier 131b is installed on the connection line between the gate of the fourth MOS FET 131a and the reference voltage supply unit 133, and a positive voltage is applied from the reference voltage supply unit 133 and the fourth MOS is applied. A negative voltage is applied from a parallel connection point between a connection line between the output terminal of the FET 131a and the common resistor 132 and a connection line between the LED lighting unit 121 and the rectifier circuit 112.

According to such a configuration, the g _m value of the equation in the description of the AC LED drive circuit 100 with reference to FIG. 4 can be greatly increased.

Therefore, since a circuit whose value of the output current of the voltage controlled current source 131 is independent of the g _m characteristic of the fourth MOS FET 131a is implemented, a more stable circuit configuration is possible.

In addition, the reference voltage supply unit 133 includes an internal source (133a) and a resistor (133b) connected to an output terminal of the current source (133a). Here, the voltage value of the current source 133a is input to the (+) input terminal of the third OP amplifier 131b, and the resistor 133b is connected in parallel on the connection line between the common resistor 132 and the rectifier circuit 112. do.

The reference voltage phase conversion unit 140 converts the input signal from the rectified circuit 112 phase-cut in the dimmer 111 into a pulse type signal and then converts the converted pulse into a reference voltage.

Therefore, the reference voltage phase converter 140 may include a pulse generator 141 and a voltage pulse converter 142.

The pulse generator 141 is connected to the output terminal of the rectifier circuit 112, and the pulse generator 141 converts the input signal phase cut in the dimmer 111 into a square wave shape.

The voltage pulse converter 142 is connected to the output terminal of the pulse generator 141 to convert the pulse signal changed by the pulse generator 141 into a reference voltage.

6 is a diagram illustrating a specific form of the pulse generator and the voltage pulse converter.

As shown, the pulse generator 341 of the reference voltage phase shifter 340 includes a first resistor 341a connected to the output terminal of the rectifier circuit 112 and a second resistor connected in series with the first resistor 341a. And an op amp 341c in which a positive input terminal is connected in parallel between the resistor 341b and the first resistor 341a and the second resistor 341b.

In addition, the voltage pulse converter includes a low pass filter 342 connected to an output terminal of the OP amplifier 341c included in the pulse generator 341.

The rest of the configuration except for the reference voltage phase shifter 340 of FIG. 6 is the same as those of the AC LED driving circuit 200 according to the embodiment of FIG. 5, and accordingly, the reference voltage phase shifter 340 of FIG. 6. Only the reference numerals of) and the rest of the configuration of the AC LED driving circuit 300 and reference numerals and detailed description of each configuration will be omitted.

And the process of the reference voltage phase conversion of the AC LED driving circuit described with reference to FIG. 5 will be described with reference to FIG.

First, the phase cut dimmed waveform is scaled down to a low voltage, and then input to a comparator with a specific reference voltage. A pulse signal is generated as shown in FIG. 7.

When the generated duty signal is passed through a low pass filter, a signal having a different magnitude may be generated according to the duty value. That is, as shown in FIGS. 8 and 9, a high voltage when the dimming angle is high, and a low voltage signal may be generated when the dimming angle is low. It can be used as the reference voltage of and can implement dimming function.

Next, another embodiment of the pulse generator and the voltage pulse converter in the AC LED driving circuit of FIG. 5 will be described with reference to FIG. 10.

As illustrated, the pulse generator 441 of the reference voltage phase shifter 400 includes a first resistor 441a connected to an output terminal of the rectifier circuit 112 and a second resistor connected in series with the first resistor 441a. And an op amp 441c in which a positive input terminal is connected in parallel between the resistor 441b and the first resistor 441a and the second resistor 441b.

The voltage pulse converter 442 includes an integrator 442a connected to the output terminal of the OP amplifier 441c included in the pulse generator 441 and a sample hold circuit 442b connected to the output terminal of the integrator 442a. Hold Circuit).

In addition, the voltage pulse converter 442 is connected to the output terminal of the rectifier circuit 112 to generate a signal of the sampling time based on the output voltage output through the rectifier circuit 112, and the sample hold based on the generated signal The apparatus may further include a sampling time reference signal generator 442c for controlling the circuit 442b.

The rest of the configuration except for the reference voltage phase shifter 440 of FIG. 10 is the same as those of the AC LED driving circuit 200 according to the embodiment of FIG. 5, and accordingly, the reference voltage phase shifter 440 of FIG. 10. Only the reference numerals of) and the rest of the configuration of the AC LED driving circuit 400 and reference numerals and detailed description of each configuration is omitted.

5, 6, and 10, after converting the input signal of the reference voltage

phase conversion unit

140, 340, 440 into a pulse signal, and converting the converted pulse signal into a reference voltage is illustrated in FIGS. 5, 6, and 6. There may be more forms in addition to the embodiment of 10. Therefore, the reference voltage phase shifter of the present invention is not limited to the embodiment of FIGS. 5, 6, and 10, and the output terminal and the dimmer driver of the rectifier circuit 112 ( A condition for generating a control voltage for varying the driving current of the LED driver 120 based on the detected dimming angle after detecting the dimming angle of the voltage input to the dimmer driver 130 by being connected to the connection line between the 130 lines. More modifications can be made within the range to be satisfied.

11 and 12 illustrate another embodiment of the LED driver in the AC LED driver circuit of FIG. 5.

First, in the case of the AC LED driving circuit 500 of FIG. 11, the current channel switching unit 122 further includes a third resistor 122c as compared to the AC LED driving circuit 200 of FIG. 5. There is.

That is, the current channel switching unit 122 has a third MOS FET 122a connected to the output terminal of the LED lighting unit 120, and an output terminal is connected to the third MOS FET 122a of the current channel switching unit 122. The output terminal and the charging voltage switching control unit of the second OP amplifier 122b to which the reference voltage and the output voltage of the third MOS FET 122a are respectively input to the input terminal, and the third MOS FET 122a of the current channel switching unit 122. And a third resistor 122c provided on the connection line with the second resistor 124d of 124.

As described above, since the AC LED driving circuit 500 includes the third resistor 122c in the current channel switching unit 122 as compared with the AC LED driving circuit 200 of FIG. 5, FIG. 5. The same reference numerals are used for parts common to and the detailed description thereof is omitted.

The AC LED driving circuit 500 has the reference voltage VREF1 input to the first OP amplifier 124c of the charging voltage switching controller 124 and the second OP amplifier 122b of the current channel switching unit 122 according to this configuration. Between the reference voltage VREF2 input to the second resistor 124d of the charging voltage switching control unit 124 and the third resistor 122c of the current channel switching unit 122.

The conditions of

With this configuration, the second OP amplifier 122b, the third MOS FET 122a and the third resistor 122c of the current channel switching unit 122 form a main current source. When the voltage V1 is lower than the voltage VT required for driving the main current source and the LED lighting unit 120, the first resistor 124b and the first OP amplifier 124c of the charging voltage switching control unit 124 are charged by the charging voltage of the voltage V2. ), An auxiliary current source formed of the second MOS FET 124a and the common resistor 132 is driven to generate a voltage difference value between the source-gate of the third MOS FET 122a of the current channel switching unit 122. When the voltage difference between the source and gate of the third channel MOS FET 122a of the current channel switch 122 is greater than the threshold voltage of the third MOS FET 122a of the current channel switch 122, the voltage charger 123 The voltage charged in the capacitor 123a is applied to the LED lighting unit 120 and the current channel switching unit 122 to supply the voltage necessary for the main current source. That is, the first MOS FET is in an open state when V1> VT, a short state when V1 ≦ VT, and a transition to a short state when V1 = VT.

The reference voltage VREF1 input to the first OP amplifier 124c of the charging voltage switching controller 124 and the reference voltage VREF2 input to the second OP amplifier 122b of the current channel switching unit 122 for the series of operations. In addition, between the second resistor 124d R2 of the charging voltage switching controller 124 and the third resistor 122c of the current channel switching unit 122.

The condition must be established.

In addition, the AC LED driving circuit 600 according to FIG. 12 is different from the AC LED driving circuit 200 according to FIG. 5 in that the charging voltage switching controller 124 further includes a fourth resistor 124e. .

That is, the charging voltage switching controller includes a second MOS FET 124a, a first resistor 124b, a first OP amplifier 124c, a second resistor 124d, and a fourth resistor 124e.

The fourth resistor 124e is on the connection line between the output terminal of the third MOS FET 122a of the current channel switching unit 122 and the negative voltage input terminal of the first MOS FET 124a of the charging voltage switching controller 124. At the same time, the output terminal of the third MOS FET 122a of the current channel switching unit 122 is connected in parallel with the second resistor 124d of the charging voltage switching control unit 124.

The reference voltage VREF1 input to the first OP amplifier 124c of the charging voltage switching controller 124 and the reference voltage VREF2 input to the second OP amplifier 122b of the current channel switching unit 122 and the second resistor 124d. ) And the fourth resistor 124e

The conditions of

The operation of the AC LED driving circuit 600 according to FIG. 10 described above will be understood based on the AC

LED driving circuits

200 and 500 according to FIGS. 5 and 11.

As can be seen through the above-described embodiment of Figures 4 to 12, the AC LED driving circuit according to the present invention, it is possible to significantly improve the flicker free characteristics and to implement a high power factor (power factor) At the same time, the dimmer always operates normally.

As described above, the present invention has been described in detail by specific embodiments such as specific components and the like, but the drawings are provided to help a more general understanding of the present invention, and the present invention is limited to the above embodiments. In other words, various modifications and variations are possible to those skilled in the art to which the present invention pertains.

Therefore, the spirit of the present invention should not be limited to the described embodiments, and all the things that are equivalent to or equivalent to the scope of the claims as well as the following claims will belong to the scope of the present invention.

The present invention can be widely used in the LED drive circuit.

Claims

A power supply unit including a dimmer receiving an AC voltage of an AC power source and a rectifier circuit for the output voltage of the dimmer;

An LED lighting unit connected to an output terminal of the rectifier circuit, a current channel switching unit connected to an output terminal of the LED lighting unit to form a current supply channel of the LED lighting unit, and a parallel connection line between the power supply unit and the LED lighting unit; An LED driver including a voltage charging unit configured to charge voltage from a power supply and selectively supply a charging voltage to the LED lighting unit having a switching function for the LED lighting unit, and a charging voltage switching control unit controlling a switching function of the voltage charging unit;

A voltage controlled current source (VCCS) having an input terminal and an output terminal connected to the connection line between the rectifying circuit and the input terminal of the LED lighting unit and the connection line between the output terminal of the LED lighting unit and the rectifying circuit, and the voltage controlled current source. The voltage is controlled in parallel on a connection line including a common resistor commonly connected to an output line of the LED lighting unit and a connection line between the output terminal of the LED lighting unit and the rectifier circuit and the common resistor between the output terminal of the voltage controlled current source and the rectifier circuit. And a reference voltage supply unit configured to apply a positive reference voltage to a current source, wherein an output voltage of the voltage controlled current source connected in series with the common resistor is input as a negative voltage of the voltage controlled current source so that the LED driver is driven from the rectifying circuit. A dimmer driver including a current supplied to the negative feedback path;

LED lighting unit included in the LED driving unit based on the value of the dimming angle is detected after sensing the dimming angle (dimming angle) of the voltage input to the dimmer driving unit connected to the connection line between the output terminal of the rectifier circuit and the dimmer driving unit AC LED driving circuit including a reference voltage phase shift unit for generating a control voltage for varying the drive current.
The method of claim 1,

And the reference voltage phase converting unit converts an input signal from the rectifying circuit phase-cut in the dimmer into a pulse signal and converts the converted pulse into a reference voltage.
The method of claim 1, wherein the reference voltage phase conversion unit,

A pulse generator connected to an output terminal of the rectifier circuit and converting an input signal phase cut in the dimmer into a square wave form;

And a voltage pulse converter connected to an output terminal of the pulse generator to convert a pulse signal changed by the pulse generator into a reference voltage.
The method of claim 3, wherein

The pulse generator includes a first resistor connected to an output terminal of the rectifier circuit, a second resistor connected in series with the first resistor, and an OP amplifier in which a positive input terminal is connected in parallel between the first resistor and the second resistor. ,

And the voltage pulse converter comprises a low pass filter connected to an output terminal of the OP amplifier.
The method of claim 3, wherein

The pulse generator includes a first resistor connected to an output terminal of the rectifier circuit, a second resistor connected in series with the first resistor, and an OP amplifier in which a positive input terminal is connected in parallel between the first resistor and the second resistor. ,

The voltage pulse converter includes an integrator connected to an output terminal of the OP amplifier and a sample and hold circuit connected to an output terminal of the integrator.
The method of claim 3, wherein

The voltage pulse converter may be connected to an output terminal of the rectifier circuit to generate a sampling time signal based on an output voltage output through the rectifier circuit, and to control the sample and hold circuit based on the generated signal. AC LED drive circuit further comprising.
The method of claim 1,

The voltage charging unit of the LED driver includes a capacitor connected to a connection line between the power supply unit and the LED lighting unit, and a first MOS FET installed on the connection line between the capacitor and the LED lighting unit to perform a switching function.

The charge voltage switching controller may include a second MOS FET connected to the capacitor-side contact of the first MOS FET, a first resistor disposed on a connection line between the capacitor-side contact of the first MOS FET and the second MOS FET. And an output terminal connected to the second MOS FET and commonly connected to a first OP amplifier to which a reference voltage and an output voltage of the second MOS FET are input, an output terminal of the second MOS FET, and the current channel switching unit. A second resistor,

The current channel switching unit includes a third MOS FET connected to an output terminal of the LED lighting unit, a second OP amplifier connected to an output terminal of the third MOS FET, and a reference voltage and an output voltage of the third MOS FET are respectively input to the input terminal. Including,

A condition of VREF1 < VREF2 is established between the reference voltage VREF1 input to the first OP amplifier of the charging voltage switching controller and the reference voltage VREF2 input to the second OP amplifier of the current channel switching unit,

When the supply voltage value of the power supply unit is set to V1, and the voltage value necessary for normal operation of the LED lighting unit and the current channel switching unit is set to VT, the first MOS FET is open when V1> VT, and V1. An alternating current LED driving circuit comprising a short circuit state when ≤ VT and a short circuit state when V1 = VT.
The method of claim 1,

The voltage charging unit of the LED driver includes a capacitor connected to a connection line between the power supply unit and the LED lighting unit, and a first MOS FET installed on the connection line between the capacitor and the LED lighting unit to perform a switching function.

The charge voltage switching controller may include a second MOS FET connected to the capacitor-side contact of the first MOS FET, a first resistor disposed on a connection line between the capacitor-side contact of the first MOS FET and the second MOS FET. And an output terminal connected to the second MOS FET and commonly connected to a first OP amplifier to which a reference voltage and an output voltage of the second MOS FET are input, an output terminal of the second MOS FET, and the current channel switching unit. A second resistor,

The current channel switching unit includes a third MOS FET connected to an output terminal of the LED lighting unit, a second OP amplifier connected to an output terminal of the third MOS FET, and a reference voltage and an output voltage of the third MOS FET are respectively input to an input terminal; A third resistor disposed on a connection line between an output terminal of the third MOS FET and a second resistor of the charging voltage switching controller;

The reference voltage VREF1 input to the first OP amplifier of the charging voltage switching controller, the reference voltage VREF2 input to the second OP amplifier of the current channel switching unit, and a second resistor and a third resistor are as follows.

AC LED drive circuit, characterized in that the conditions of.
The method of claim 1,

The voltage charging unit of the LED driver includes a capacitor connected to a connection line between the power supply unit and the LED lighting unit, and a first MOS FET installed on the connection line between the capacitor and the LED lighting unit to perform a switching function.

The charge voltage switching controller may include a first resistor disposed on a connection line between a second MOS FET connected to the capacitor side contact of the first MOS FET, the second MOS FET, and the capacitor side contact of the first MOS FET. And a first connection connected to an output terminal of the second MOS FET and a reference voltage and an output voltage of the second MOS FET to an input terminal, a common connection to an output terminal of the second MOS FET, and an output terminal of the current channel switching unit. A second resistor, a fourth resistor disposed on a connection line between the second resistor and an output terminal of the second MOS FET;

The current channel switching unit may include a third MOS FET connected to an output terminal of the LED lighting unit and a second OP amplifier connected to an output terminal of the third MOS FET, and a reference voltage and an output voltage of the third MOS FET are respectively input to an input terminal. Including,

The reference voltage VREF1 input to the first OP amplifier of the charging voltage switching controller, the reference voltage VREF2 input to the second OP amplifier of the current channel switching unit, and a second resistor and a fourth resistor are as follows.

AC LED drive circuit, characterized in that the conditions of.
The method according to any one of claims 7 to 9,

The dimmer driving unit includes a MOS FET in which the voltage control current source is connected to a drain line at a connection line between the output terminal of the rectifier circuit and the first LED unit, a source is connected to the common resistor, and a gate is connected to the reference voltage supply unit. ,

The reference voltage supply unit includes a resistor connected to an internal supply (Iref) and an output terminal of the MOS FET, a gate of the MOS FET is connected on a connection line of the current source and a resistor, and the resistor is connected to the common resistor; AC LED drive circuit, characterized in that connected in parallel on the connection line between the rectifier circuit.
The method of claim 1,

The LED lighting unit includes an n-th LED lighting unit located at the longest distance from the output terminal of the rectifying circuit, starting with the first LED lighting unit located at the shortest distance from the output terminal of the rectifying circuit.

And the current channel switching unit is individually connected to an output terminal of each of the first to n th LED lighting units to form a current supply channel for the corresponding LED lighting unit.