TW201406204A - Universal type dimming control device for LED driver - Google Patents

Abstract

A universal type dimming control device for an LED driver includes a power supply unit, a high level limiting unit, a low level limiting unit and a dimming control unit. The high level limiting unit can output a first level voltage corresponding to the variation of the dimming signals. The low level limiting unit can be driven and conducted by the first level voltage for correspondingly outputting a second level voltage. The dimming control unit can output a DC control level voltage corresponding to the second level voltage for driving the LED driver to adjust LED brightness. Through the above design, the universal type dimming device of the present invention is applicable to variously kinds of LED drivers, and can freely select a resistance signal, a DC electrical signal and a pulse width modulation signal as a dimming signal source, so as to have larger market competitive advantage.

Description

General-purpose dimming control device for LED driver

The present invention relates to a dimming control device, and more particularly to a dimming control device for an LED driver.

The conventional LED dimming method is roughly divided into primary side dimming and secondary side dimming. Regarding primary side dimming, the most commonly used is Triac dimming. This dimming method used to be mainly used in tungsten filament bulbs. It is also widely used in LED lamps. The principle of operation is to change the conduction angle of the input voltage. In order to change the output current, the advantages of the primary side dimmer are that the structure is simple and the installation is convenient, but the disadvantage is that the matching between the dimmers and the LED driver is not good, and the LED lamp is easily flickered and the efficiency is low.

The most common dimming methods in secondary side dimmers can be divided into DC voltage signal dimming and pulse width modulation signal dimming. The dimming design for LED drivers has the following two architectures.

As shown in FIG. 1, the front stage 101 of the LED driver 100 is a power factor adjustment stage, and a flyback converter is used as the main line. The rear pole 102 is mainly a DC/DC converter 103, and the dimming function is handled by an integrated IC 200 mounted on the DC/DC converter 103. However, the integrated IC 200 with dimming function is only applicable to a single dimming signal, such as a pulse width modulation signal (PWM signal) or a 1-10 V DC signal (V _dc). Signal) cannot be used for various dimming signals, so once the user wants to use different types of dimming signals, it is inevitable that the integrated IC 200 must be replaced.

As shown in FIG. 2, the previous stage 101 of the LED driver 100 is mainly based on buck conversion or boost conversion, and power factor correction, and the rear stage 102 is DC/DC conversion, mainly based on a flyback converter, and dimming. The function is implemented by the dimming controller 201 mounted on the rear pole 102. The dimming controller 201 mainly corrects the dimming signal through a comparator (not shown) and an amplifier (not shown), and then outputs a change LED. The feedback state of the driver 100 is used to achieve the dimming effect. Due to different designs, the dimming signal that can be received can only be a pulse width modulation signal, a DC signal or a resistance signal. The dimming controller 201 cannot be commonly used for both pulse width modulation signals and DC signals. Or a dimming signal source such as a resistor signal, so the dimming controller 201 has poor applicability.

Therefore, the object of the present invention is to provide a general-purpose dimming control device for driving LED drivers for LED dimming, and for PWM signals, DC signals and resistance signals as dimming signals.

Therefore, the general-purpose dimming control device of the LED driver of the present invention is suitable for being mounted on the LED driver, and can input a dimming signal, and can drive the LED driver to change according to the dimming signal change. The controlled LED brightness, the dimming signal is selected from the group consisting of a resistor signal, a DC signal, and a pulse width modulation signal, and the general-purpose dimming control device includes a power supply unit that provides a DC output. A high level limiting unit, a low level limiting unit, and a dimming control unit.

The high level limiting unit is electrically connected to the output end of the power supply unit, and has two dimming signal terminals for inputting the dimming signal, and is rootable According to the dimming signal change, a first level voltage is output correspondingly. The low level limiting unit is electrically connected between the output end of the power supply unit and the high level limiting unit, and can be driven to be turned on when the first level voltage of the input is greater than a threshold, and the corresponding output is Two level voltage. The dimming control unit is electrically connected to the low level limiting unit and is electrically connected to the LED driver, and includes a filter capable of filtering the second level voltage and outputting a corresponding one for driving the LED driver to be modulated. A low-pass filter circuit for DC control level voltage of LED brightness.

The effect of the invention: through the design of the high level limiting unit, the low level limiting unit and the dimming control unit, in addition to making the universal dimming device of the invention applicable to a plurality of LED drivers, the selection of the dimming signal In addition, it is also free to choose the resistor signal, DC signal and pulse width modulation signal as the dimming signal source, and has a competitive advantage in the market.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments of the invention.

Before the present invention is described in detail, it is noted that in the following description, similar elements are denoted by the same reference numerals.

As shown in FIGS. 3 and 4, the first preferred embodiment of the general-purpose dimming control device for the LED driver of the present invention is suitable for electrical connection to be mounted on an LED driver 9, for driving the LED driver 9 to be modulated. Controlling the brightness of the LED 800, and the general-purpose dimming control device can be electrically connected to install a variable resistor, a DC voltage source and a pulse width modulator, and optionally One of the resistor signal, the Vdc signal, and the PWM signal is selected as the dimming signal source.

The LED driver 9 includes an EMI unit 901 electrically connected to an AC power source 900, a bridge rectifier unit 902, a transformer 903, and an electrical connection to the secondary side of the transformer 903. An output rectifying unit 904 for driving the LED 800, a constant current/constant voltage control unit (FC/CV controller unit) 905 electrically connected to the output end of the output rectifying unit 904, and an electrical connection to the output of the constant current/constant voltage control unit 905 The end feedback unit 906, and a power factor adjustment/pulse width adjustment control unit (PFC/PWM controller unit) 907 electrically connected to the output end of the feedback unit 906 and the primary side of the transformer 903. The general-purpose dimming control device of the present invention is electrically connected to the constant current/constant voltage control unit 905, and can be used to control the magnitude of the feedback current output by the constant current/constant voltage control unit 905, thereby driving the LED driver 9 to adjust Change the purpose of LED 800 brightness.

The general-purpose dimming control device includes a power supply unit 3, a low level limiting unit 5 electrically connected to the output end of the power supply unit 3, and an electrical connection to the output of the power supply unit 3 and the low level. a high level limiting unit 4 for limiting the dimming signal between the units 5 and an electrical connection to the output of the low level limiting unit 5 for electrically connecting to the constant current/constant voltage control unit 905 The dimming control unit 6 and the general-purpose dimming control device directly acquire the required power from the LED driver 9.

The power supply unit 3 includes a power supply element V _O , a first resistor R ₁ electrically connected between the anode of the power supply element V _O and the low level limiting unit 4 and the high level limiting unit 5 , and a parallel connection V _O negative electrode of the power supply device of the first resistor R ₁ of the constant voltage element ZD _1. In this embodiment, the power supply component V _O is a storage capacitor, and the power can be obtained from the LED driver 9 . However, when implemented, the power supply component V _O can also be an independently powerable battery component. The voltage stabilizing element ZD ₁ is an arrester diode, the cathode thereof is electrically connected to the first resistor R ₁ , and the anode thereof is electrically connected to the negative pole of the power supply element V _O and grounded, and the voltage stabilizing element ZD ₁ are both in the oN state to the outer design variable resistance R _a combined resistance variation range.

The high level limiting unit 4 includes a second resistor R ₂ and a voltage stabilizing circuit 41. The voltage stabilizing circuit 41 includes a third resistor R ₃ , a fourth resistor R ₄ , and an adjustable precision shunt regulator 411 . The adjustable precision shunt regulator 411 has a cathode (-), an anode (+) and a reference pole (ref), and the anode is grounded. In this embodiment, the adjustable precision shunt regulator 411 is TL431. The second resistor R ₂ is electrically connected between the cathode of the voltage stabilizing element ZD _{1 and} the cathode of the adjustable precision shunt regulator 411 , and the third resistor R ₃ is electrically connected to the adjustable precision shunt regulator 411 . Between the reference pole and the cathode, the fourth resistor R ₄ is electrically connected between the reference pole and the anode of the adjustable precision shunt regulator 411. The voltage stabilizing circuit 41 further has two dimming signal terminals Dim+ and Dim- respectively connected to the cathode and the anode of the adjustable precision shunt regulator 411, and the dimming signal terminals Dim+ and Dim- are available for the The variable resistance, the adjustable DC power supply or the pulse width modulator is connected to correspond to the input resistance signal, the DC signal and the pulse width modulation signal, and the resistance of the third resistor R ₃ and the fourth resistor R ₄ is much larger than the resistance The resistance of the variable resistor R _a .

The low level limiting unit 5 includes a diode D ₁ and a switching element Q ₁ . The diode D ₁ is electrically connected to the dimming control unit 6 with a cathode thereof. The switching element Q ₁ has a first end electrically connected to the cathode of the voltage stabilizing element ZD ₁ and is electrically connected to the diode the second end D of the body of _an anode and a cathode electrically connected to the control terminal of said adjustable precision shunt regulator 411 of the present embodiment, the switching element Q ₁ is a npn type bipolar junction transistor ( Bipolar junction transistor (BJT), the first end is a collector (C), the second end is an emitter (E), and the control end is a base (B), and the adjustable precision shunt regulator 411 is When the first level voltage (V _dim ) of the cathode terminal is greater than the forward bias voltage (V _BE ) between the control terminal and the second terminal, the first end and the second end are turned on, and when V _{dim is} greater than 1 V The diode D _{1 is} also turned on, and correspondingly outputs a second level voltage V _D . That is, when V _{dim is} greater than a threshold formed by the forward bias of the switching element Q ₁ and the diode D ₁ , the low level limiting unit 5 outputs the second level voltage V _D .

The dimming control unit 6 includes a voltage dividing circuit composed of a resistor R ₅ and a resistor R ₆ , and a low-pass filter circuit composed of a resistor R ₅ and a capacitor C ₁ , which can output the low level limiting unit 5 . After the second level voltage V _D is divided, it is filtered into a DC current control level voltage (V _ctrl ) output to modulate the feedback current output by the constant current/constant voltage control unit 905.

Hereinafter, the general-purpose dimming control device of the present invention uses three kinds of dimming signals, such as a resistor signal, a DC signal, and a pulse width modulation signal, to control the LED driver 9 to modulate the brightness of the LED 800.

Function description 1: The resistance signal of the variable resistor R _a is used as the source of the dimming signal.

A variable resistor R _{a is} connected across the dimming signal terminals Dim+ and Dim-, and the resistance of the variable resistor R _a is much smaller than the resistance of the third resistor R ₃ and the fourth resistor R ₄ . pressure element ZD ₁ in the variable resistance R _a of the resistance adjusting range are in a conducting state. At this time, the first level voltage V _{dim is} as shown in (Formula 1).

Since R _{a is} much smaller than R ₃ and R ₄ , (Formula 1) can be equivalent to (Formula 2).

Moreover, since the voltage stabilizing circuit 41 of the high level limiting unit 4 is constituted by the adjustable precision shunt regulator 411, the circuit characteristic of the adjustable precision shunt regulator 411 is used to effectively limit the maximum value of the V _dim . Avoid V _dim too large, such as (Formula 3).

When V _{dim is} greater than 1V, and the low level limiting unit 5 is turned on, the output second level voltage V _{D is} as shown in (Formula 4), and the entire general-purpose dimming control device output is used to drive the LED driver. The control level voltage V _ctrl is as shown in (Formula 5).

V _D = V _dim - V _BE - V _{D 1} (Formula 4)

Also due to V _{BE 1} + V _{D 1} 1V (Equation 6)

By bringing (Formula 2) and (Formula 6) into (Formula 5), (Formula 7) is obtained.

Since R ₂ , R ₅ , R ₆ and V _ZD1 are all fixed values, the V _ctrl level changes with the modulation of R _a , thereby changing the magnitude of the feedback current output by the constant current/constant voltage control unit 905. And achieve the purpose of dimming.

Function Description 2: The power signal of the adjustable DC voltage source V _dc is used as the dimming signal.

As shown in FIG. 3 and FIG. 5, the adjustable DC voltage source V _dc of the present invention has a voltage range of 1-10 V. At this time, according to the circuit characteristics of the adjustable precision shunt regulator 411, the first standard The bit voltage V _{dim is} as shown in (Expression 8).

Further introducing (Equation 8) and (Equation 6) into (Equation 5), we can derive (Equation 9), the V _ctrl level will vary linearly with V _dc , and when V _{dc is} greater than the threshold of 1 V, The LED driver 9 can be driven to dim, so the dimming can be performed by changing the voltage value of the adjustable DC voltage source V _dc .

Function Description 3: Pulse width modulation signal V _{PWM is} used as the source of dimming signal.

As shown in FIGS. 3 and 6, the duty cycle of the _PWM signal V _PWM is D, the amplitude is V _{PWM, amp} , and the period is Ts. The second level voltage V _D across the diode D ₁ is (Equation 10), and since V _D is a pulse width modulation signal, the average value of V _D is (Equation 11).

V _D = V _PWM - V _{BE 1} - V _{D 1} (Equation 10)

V _{D , amp} × D = ( V _{PWM , amp} - V _{BE 1} - V _{D 1} ) × D (Equation 11)

In addition, the second level voltage V _D is filtered by the low pass filter circuit of the dimming control unit 6 to form a DC control level voltage V _ctrl , and V _ctrl is an average value of V _D , so V _{ctrl is} as in Equation 12 ) shown. Further, by introducing (Formula 6) and (Formula 11) into (Formula 12), V _ctrl as shown in (Formula 13) can be obtained.

V _ctrl = ( V _{PWM , amp} -1) × D (Equation 13)

According to (Formula 12), since V _{PWM and amp} are constant values, V _ctrl will change with the duty cycle of the pulse width modulation signal, so by adjusting the size of the duty cycle of the pulse width modulation signal, Reach the purpose of dimming.

According to the above three dimming function descriptions, the general-purpose dimming control device of the present invention can be applied to any one of a resistance signal, a DC signal, and a pulse width modulation signal as a dimming signal source, and has a precise dimming function, and The overall circuit design is quite simple, so the user can arbitrarily select one of the dimming signal sources according to the requirements of the use, and it is no longer necessary to change the dimming device to change the dimming signal source, which is more than the conventional dimming device. Competitive in the market.

In addition, when the user no longer needs to drive the LED driver 9 to perform LED dimming, the user does not need to remove the general-purpose dimming control device, and only needs to interrupt the resistance of the dimming signal terminals Dim+ and Dim-. The input of the signal, DC signal or pulse width modulation signal does not affect the normal operation of the LED driver 9, and the dimming function of the general-purpose dimming control device can be re-enabled in the future.

Furthermore, it must be noted that the general-purpose dimming control device of the present invention can be applied to other single-stage or two-stage designs with constant current control design, in addition to the LED driver 9 structure shown in FIG. The architecture of the LED driver, such as the two dual-stage LED driver architectures shown in Figures 1 and 2.

As shown in FIG. 7, the second preferred embodiment of the general-purpose dimming control device for the LED driver of the present invention differs from the first embodiment only in that the voltage regulator circuit 41 of the high-level limiting unit 4 is designed. For convenience of explanation, only the differences between the present embodiment and the first embodiment will be described below.

This high level limiting unit 41 of the voltage regulator circuit 4 comprises a zener diode ZD _2, the zener diode ZD ₂ is connected with its cathode to the second resistor R ₂ to the switching element Q ₁ of The control terminal is grounded with its anode, and the dimming signal terminals Dim+ and Dim- are electrically connected to the cathode and the anode of the Zener diode ZD ₂ , respectively. By the characteristics of the Zener diode ZD ₂ , the maximum value of V _dim is limited to a reverse conduction voltage equal to or less than the magnitude of the Zener diode ZD ₂ .

When these dimming signal is connected across a variable resistor R _a, V _dim and V _ctrl respectively according to (Formula 2) shown, V _ctrl level (Formula 7) of the variable resistor likewise with R _a The change of the tone changes, thereby driving the LED driver to modulate the brightness of the LED.

When the dimming signal terminals Dim+ and Dim- are connected to the _DC power source V _dc , the first level voltage V _dim is equal to V _dc , so V _dim is further as shown in (Expression 14), and V _ctrl can be further derived as described above. The result of (Formula 9). Therefore, V _ctrl also changes linearly with V _dc change, which in turn allows the LED driver to adjust the brightness of the LED as V _dc changes.

When the dimming signal such end Dim +, Dim- across a PWM signal V _PWM, the voltage across the diode D _1, V _D and the (Formula 10) the same, it is possible to further push the (formula 13) V _ctrl . Therefore, the V _ctrl will also change with the duty cycle of the pulse width change signal, and can also drive the LED driver to modulate the LED brightness.

The general-purpose dimming control device of this embodiment is also applicable to various LED drivers using a constant current control design.

In summary, through the design of the high level limiting unit 4, the low level limiting unit 6 and the dimming control unit 6, in addition to making the universal dimming device of the present invention applicable to a plurality of LED drivers 9, In the choice of optical signal, it is also free to choose the resistor signal, DC signal and pulse width modulation signal as the dimming signal source, and can accurately dim, but has a wide range of applications, and the overall circuit design is quite simple and easy. It is manufactured with low cost and has a competitive advantage in the market. Therefore, the object of the present invention can be achieved.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent.

3‧‧‧Power supply unit

R ₅ , R ₆ ‧ ‧ resistance

V _o ‧‧‧Power supply unit

C ₁ ‧‧‧ capacitor

R ₁ ‧‧‧first resistance

800‧‧‧LED

ZD ₁ ‧‧‧ Voltage Regulator

9‧‧‧LED driver

4‧‧‧High level limit unit

AC‧‧‧AC power supply

R ₂ ‧‧‧second resistance

901‧‧‧Electromagnetic filter circuit

41‧‧‧Variable circuit

902‧‧‧Bridge rectifier unit

411‧‧‧Adjustable Precision Shunt Regulator

903‧‧‧Transformer

904‧‧‧Output rectifier unit

ZD ₂ ‧‧‧Jenner diode

905‧‧‧Constant current / constant voltage control unit

Dim+, Dim-‧‧‧ dimming signal end

R ₃ ‧‧‧third resistor

906‧‧‧Return unit

R ₄ ‧‧‧fourth resistor

907‧‧‧Power factor adjustment / pulse width adjustment control unit

5‧‧‧low level limit unit

D ₁ ‧‧‧ diode

R _a ‧‧‧resistance signal

Q ₁ ‧‧‧Switching elements

V _dc ‧‧‧DC signal

6‧‧‧ dimming control unit

V _PWM ‧‧‧ pulse width modulation signal

1 is a functional block diagram of a dimming control design of a conventional LED driver; FIG. 2 is a functional block diagram of another conventional dimming control design of an LED driver; FIG. 3 is a general-purpose dimming control device for an LED driver of the present invention; First A preferred embodiment is a functional block diagram of an LED driver; FIG. 4 is a circuit diagram of the first preferred embodiment with a resistance signal as a dimming signal source; FIG. 5 is a DC of the first preferred embodiment. The signal is a circuit diagram of a dimming signal source; FIG. 6 is a circuit diagram of the first preferred embodiment with a pulse width modulation signal as a dimming signal source; and FIG. 7 is a general-purpose dimming control device for the LED driver of the present invention. A circuit diagram of a second preferred embodiment.

3‧‧‧Power supply unit

R ₄ ‧‧‧fourth resistor

V _o ‧‧‧Power supply unit

5‧‧‧low level limit unit

R ₁ ‧‧‧first resistance

D ₁ ‧‧‧ diode

ZD ₁ ‧‧‧ Voltage Regulator

Q ₁ ‧‧‧Switching elements

4‧‧‧High level limit unit

6‧‧‧ dimming control unit

R ₂ ‧‧‧second resistance

R ₅ , R ₆ ‧ ‧ resistance

41‧‧‧Variable circuit

C ₁ ‧‧‧ capacitor

411‧‧‧Adjustable Precision Shunt Regulator

905‧‧‧Constant current / constant voltage control unit

Dim+, Dim-‧‧‧ dimming signal end

R _a ‧‧‧Variable resistor

R ₃ ‧‧‧third resistor

Claims (12)

A general-purpose dimming control device for an LED driver, which is suitable for being mounted on the LED driver for inputting a dimming signal, and capable of driving the LED driver to be controlled according to the dimming signal change LED brightness, the dimming signal is selected from the group consisting of a resistor signal, a DC signal, and a pulse width modulation signal. The general-purpose dimming control device includes: a power supply unit that provides a continuous current output; a bit limiting unit electrically connected to the output end of the power supply unit, and having two dimming signal terminals for inputting the dimming signal, and correspondingly outputting a first level voltage according to the dimming signal change; The low level limiting unit is electrically connected between the power supply unit output end and the high level limiting unit, and can be driven to be turned on when the input first level voltage is greater than a threshold value, and the corresponding output is a second a level control voltage; and a dimming control unit electrically connected to the low level limiting unit and electrically connected to the LED driver, including a filter capable of filtering the second level voltage and corresponding output The LED driver to drive the LED brightness modulation control low pass filter circuit DC level voltage. The general-purpose dimming control device for an LED driver according to the first aspect of the invention, wherein the dimming control unit further comprises an electrical connection between the output of the low-level limiting unit and the low-pass filter circuit. The second level voltage can be divided and processed and output to the voltage dividing circuit of the low pass filter circuit. The general-purpose dimming control device for an LED driver according to claim 2, wherein the low-level limiting unit includes a cathode electrically connected to the voltage dividing circuit and can be driven to be turned on to output the a second level voltage to the diode of the voltage dividing circuit, and a switching element having a first end, a second end and a control end, the first end being electrically connected to the output end of the power supply unit, The second end is electrically connected to the anode of the diode, and the control end is electrically connected to the first level voltage output end of the high level limiting unit, and the control end of the switching element is driven by the first level voltage The first end and the second end are turned on to drive the diode to conduct and output the second level voltage. The general-purpose dimming control device for an LED driver according to claim 3, wherein the switching element is an npn bipolar junction transistor, the first end is a collector, and the second end is an emitter The control terminal is the base. The general-purpose dimming control device for an LED driver according to claim 3, wherein the high-level limiting unit includes an electrical connection between the output end of the power supply unit and the control end of the switching element. a second resistor, and a voltage stabilizing circuit electrically connected to the control terminal and grounded. The general-purpose dimming control device for an LED driver according to claim 5, wherein the voltage stabilizing circuit comprises a synchronizing diode electrically connected to the control terminal by its cathode and grounded by an anode thereof. The dimming signal terminals are electrically connected to the cathode and the anode of the arrester diode, respectively. A general-purpose dimming control device for an LED driver according to claim 5, wherein the voltage stabilizing circuit includes a third resistor, a first a four-resistor and an adjustable precision shunt regulator having a cathode electrically connected to the control terminal, a grounded anode, and a reference pole electrically connected to the adjustable precision The cathode of the shunt regulator is connected between the reference pole and the reference pole, and the fourth resistor is electrically connected between the reference pole and the anode of the adjustable precision shunt regulator. The general-purpose dimming control device for an LED driver according to claim 7, wherein the adjustable precision shunt regulator is TL4ZD1. The general-purpose dimming control device for an LED driver according to claim 6 or 7, wherein the power supply unit includes a power supply element for direct current, a positive electrode electrically connected to the power supply element, and the a first resistor between the first end of the switching element and a voltage stabilizing element connected in parallel between the negative electrode of the power supply element and the first resistor. The general-purpose dimming control device for an LED driver according to claim 9, wherein the voltage stabilizing element is a Zener diode, and the cathode thereof is electrically connected to the first end of the switching element, and The anode is electrically connected to the negative electrode of the power supply element and grounded. The general-purpose dimming control device for an LED driver according to claim 9, wherein the power supply element is a storage capacitor. The general-purpose dimming control device for an LED driver according to claim 9, wherein the power supply element is a battery element.