KR101415345B1 - LED driving circuit for optical-volume controlling according to shifting of source voltage - Google Patents

Abstract

The present invention can minimize the change of the final LED emission amount even when the absolute value of the AC power is changed in the LED lighting driving circuit of the AC direct type and thus it is possible to maintain the stable operation state without flickering or shaking of the light even in the unstable power source state The present invention relates to an LED light driving circuit having a light amount compensating function when a power supply voltage is changed, and an LED light driving circuit having a light amount compensating function for a power supply voltage change according to the present invention includes a power supply unit to which external AC power is supplied, And an n-th LED located at a longest distance from the power supply unit, starting from a first LED located at a shortest distance from a connection point between the power supply unit and the power supply unit, A plurality of LEDs connected in series to each other and connected to the power source unit, A plurality of switching circuit units individually connected to the output terminals of the LEDs forming the LED illumination unit to form current supply channels for the LEDs; and a plurality of switching circuits connected in parallel to the connection line between the power supply unit and the first LEDs, A power supply voltage correcting part for outputting an adjusting signal of a current value supplied to the LED illuminating part when an absolute value of an input AC power is changed; and a power supply voltage correcting part for applying a reference voltage to each of the switching circuit parts on the basis of a signal inputted from the power supply voltage correcting part And a reference voltage supply unit.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED lighting circuit having an optical power compensation function for changing a power supply voltage,

The present invention relates to an LED lighting driving circuit having a light amount compensating function at the time of a power supply voltage change, and in particular, even if an absolute value change of an AC power source occurs in an LED lighting driving circuit of an AC direct type, And more particularly, to an LED light driving circuit having a light amount compensation function when a power supply voltage changes so that a stable operation state can be maintained without flickering or fluctuation of light even in a power supply state in which lighting is unstable.

LED (Light Emitting Diode) is a current driving device, and can be operated normally if a constant current is supplied stably. In particular, LEDs requiring high power have a large driving current (typically, 350 mA or more), so that the LED itself generates a lot of heat, and therefore, the deterioration rate of brightness is larger than that of LEDs at low power. This leads directly to the lifetime of the LED and is a very important factor in the lighting market.

In the case of the initial LED illumination, it is usually implemented as a buck type of a switched mode power supply (SMPS), and is implemented as a fly-back type using a transformer in consideration of an insulation function. However, a fly-back type of primary side regulation (PSR) has been proposed and developed for a short period of time.

Recently, an alternating direct type LED lighting driving method has been proposed and implemented in which the number of large reactive components is dramatically reduced.

In such an AC direct LED lighting driving method, an AC power source is directly applied to an LED column, a number of LEDs suitable for a voltage value of an AC power source varying in time is selected, and a current source is arranged in parallel . In other words, buck, fly-back, and PSR fly-back, which can be classified as a conventional SMPS (Switched Mode Power Supply) scheme, basically convert AC power to DC voltage to drive the LED, In an illumination driving method, an AC power source is basically applied to a row of LEDs.

FIG. 1 is a conceptual view of a conventional AC direct LED lighting driving circuit, which is an example of a case without a dimmer. The AC power supply 10, the rectifier rectifier 20, the plurality of LEDs 31 to 34, Current sources 41 to 44 corresponding to the number of LEDs 31 to 34, and an algorithm circuit for controlling the entire circuit.

2 is a conceptual view of a conventional AC direct type LED lighting driver circuit having a dimmer. Like FIG. 1, an AC power source 10, a rectified rectifier 20, a plurality of LEDs 31 to 34, Current sources 41 to 44 corresponding to the number of the LEDs 31 to 34 and an algorithm circuit for controlling the entire circuit and at the same time a dimmer 50 and bleeding for stable driving of the dimmer 50 ) Current source 60 as shown in Fig.

The LED driving circuit of the AC direct type according to FIGS. 1 and 2 does not require a large value inductor or a transformer as compared with the conventional SMPS type LED driving circuit, There is no need for a large value electrolytic capacitor, the control algorithm is relatively simple, and consequently, it has an advantage in the number of components, manufacturing process and module size.

However, while the LED lighting driver circuit of the AC direct type according to FIGS. 1 and 2 has the above-described advantages, when the magnitude of the AC voltage instantaneously changes, the brightness of the LED also reacts momentarily, , The brightness of the LED also periodically responds to the user's eyes, resulting in flickering of the LED lights and poor operation of the shaking.

In other words, according to designing the driving circuit of the SMPS type LED lighting, the brightness of the LED may be changed due to the unstable AC voltage in the actual operating environment. However, in the SMPS type LED lighting driving circuit, It is clear that the AC power supply has a structural advantage in that it operates in an unstable operation even if its influence is reduced.

On the other hand, the conventional direct current type LED lighting driving circuit is basically a system for appropriately lighting the LED when the power voltage is generated. Accordingly, in the conventional direct current type LED lighting driving circuit, when the magnitude of the AC voltage changes, This flashing section also changes its behavior.

3 (a) and 3 (b), (a) shows the change of the current waveform according to the power supply change in the conventional direct current LED lighting driving circuit (without dimmer), The change of the current waveform due to the power change in the AC direct LED lighting driving circuit (without the dimmer) is shown.

As shown in the figure, when the AC voltage changes to one-degree in the LED lighting driving circuit of the AC direct type, it can be seen that the width (L ₁ , L ₂ ) of the operating region of the current source driving the maximum current becomes wider. The phenomenon occurs regardless of the presence or absence of the dimmer.

This is because the internal reference voltage for sequentially controlling the current sources in the AC direct LED lighting driving circuit is fixed, but the fluctuation occurs in the current source as the external power source changes in size only at the same frequency.

Such a phenomenon is a major factor for the user to recognize the light state of the LED light as a state of flicker and shake. This solution is very important for improving the function of the AC light emitting diode driving circuit.

Korean Patent No. 10-0969817 (Jul. 2010), " Driving Circuit Device and Control Method of LED Light " Korean Registered Patent No. 10-1021623 (Mar. 4, 2011), " LED light device with power failure compensation function "

Even when an absolute value of an alternating current power source is changed in an AC direct current LED lighting driving circuit, the change in the final LED emission amount is minimized, and accordingly, the LED lighting can be stabilized without causing flickering or shaking of the light even in an unstable power state An object of the present invention is to provide an LED light driving circuit having a light amount compensation function when a power supply voltage changes to maintain and exhibit a lighting function.

According to an aspect of the present invention, there is provided an LED light driving circuit having a light amount compensation function when a power supply voltage changes according to the present invention includes a power supply unit to which an external AC power is supplied, And an n-th LED located at a longest distance from the power source, the first LED being connected to the power source, and each LED being connected in series to the power source, A plurality of switching circuit units individually connected to output terminals of the LEDs forming the LED illumination unit to form current supply channels for the LEDs; and a plurality of switching circuits connected in parallel to the connection line between the power supply unit and the first LEDs, And outputs an adjustment signal of a current value supplied to the LED illumination unit when the absolute value of the AC power input through the power supply unit changes And a reference voltage supply unit for applying a reference voltage to each of the switching circuit units based on a signal input from the power supply voltage correction unit.

The power supply unit may further include a dimmer connected to the power supply unit to receive an AC voltage and apply an output voltage to the rectifying circuit.

The power supply voltage correction unit may include an average voltage value calculation unit connected in parallel to a connection line between the power supply unit and the first LED, an instantaneous voltage value detection unit connected in parallel to a connection line between the power supply unit and the first LED, An arithmetic unit for receiving the output voltage values of the voltage value calculating unit and the instantaneous voltage value detecting unit, calculating the difference between the two voltage values, and outputting a value obtained by multiplying the corresponding value by a specific gain; And a reference voltage value correcting unit for subtracting the total reference voltage value from the total reference voltage value to calculate a correction value of the reference voltage value and input it to the reference voltage supply unit.

The power source voltage correcting unit may be configured to convert the AC power inputted through the power source unit into a driving voltage of the LED lighting driving circuit, which is provided on a connecting line between the power source unit and either or both of the average voltage value calculating unit and the instantaneous voltage value detecting unit, And a voltage adjusting unit for lowering the voltage.

The voltage adjusting unit is connected in series to a connection line between the power supply unit and the average voltage value calculating unit, and the instantaneous voltage value detecting unit is connected in parallel to a connection line between the voltage adjusting unit and the average voltage value calculating unit.

The average voltage value calculator calculates an average voltage value by averaging the magnitude of the power source voltage based on the waveform inputted through the voltage adjuster.

The average voltage value calculator calculates an average voltage value by averaging the total magnitude of the input power source voltage for one hour or more based on a pulse waveform reference.

The voltage regulator may be connected in parallel to a connection line between the rectifying circuit and the first LED to receive AC power of the power supply unit as an input signal or may be connected in parallel to a connection line between the power supply unit and the rectifying circuit, As an input signal.

In addition, a pair of resistors serially connected to the connection line of the voltage regulator connected in parallel to the connection line between the power supply unit and the rectifier circuit is provided so that the connection line to the voltage regulator is branched between the pair of resistors .

The instantaneous voltage value detecting unit may detect an instantaneous voltage value of the voltage level of the waveform when the magnitude of the power source voltage based on the waveform inputted through the voltage adjusting unit changes instantaneously.

The LED lighting driver circuit having the light amount compensation function according to the present invention may further include a common ground resistance to which the switching circuit portions are commonly grounded. The switching circuit portion may be connected to the LED output terminal of the LED driving portion And a comparator for comparing the reference voltage of the reference voltage supplier with the common voltage of the common ground resistance for the LED of the LED driver, the switching device being connected to the output of the comparator And the common voltage of the common ground resistance is changed by switching operation to either the first current path connected to the LED of the LED driving part and the second current path connected to the common ground resistance.

The switching element is a field effect transistor (MOS FET) having a drain connected to the LED output terminal of the LED driving unit, a source connected to the common ground resistance, and a gate connected to the comparator.

According to the present invention, even when the absolute value of the AC power is changed in the LED lighting driver circuit of the AC direct type, the change of the final LED emission amount is minimized, and accordingly, the LED lighting does not flicker or shake in the unstable power state It is possible to maintain and demonstrate a stable lighting function.

1 is a circuit diagram conceptually illustrating a configuration of a conventional direct current type LED driving circuit without a dimmer
Fig. 2 is a circuit diagram conceptually illustrating a dimming form of the conventional AC direct type LED driving circuit
3 is a diagram illustrating a change in current waveform according to a power supply change in a conventional AC direct type LED driver circuit
4 is a circuit diagram conceptually showing an LED lighting driver circuit having a light amount compensation function when the power supply voltage changes according to the present invention
5 is a circuit diagram conceptually showing another example of an LED light driving circuit having a light amount compensation function at the time of a power supply voltage change according to the present invention
6 is a circuit diagram showing an LED lighting driver circuit having a light amount compensation function at the time of a power supply voltage change according to an embodiment of the present invention.
7 is a circuit diagram showing an LED lighting driver circuit having a light amount compensation function at the time of power supply voltage change according to another embodiment of the present invention.
8 is a diagram illustrating a change in current waveform according to a power supply change in an LED lighting driver circuit having a light amount compensation function when a power supply voltage changes according to embodiments of the present invention

Hereinafter, an LED light driving circuit having a light amount compensation function according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

4 is a circuit diagram conceptually showing an LED light driving circuit having a light amount compensation function when a power supply voltage changes according to the present invention.

As shown in the drawings, an LED lighting driver circuit 100 (hereinafter, referred to as an LED lighting driver circuit) having a light amount compensation function according to the present invention according to the present invention includes a power supply 110, an LED lighting unit 120, A power supply voltage correction unit 140, a reference voltage value input unit 150, and a reference voltage supply unit 160.

The power supply unit 110 includes a power supply unit 111 and a rectification circuit 112. The power supply unit 110 may further include a dimmer 113. The power supply unit 111 is connected to an external AC power source (AC power source, hereinafter referred to as an 'AC power source') to receive the AC power source, and the rectifier circuit 112 receives AC power supplied through the power source unit 111 Rectify. The dimmer 113 is connected in series to the connection line between the power supply unit 111 and the rectification circuit 112 and receives the AC voltage from the power supply unit 111 and then applies the output voltage to the rectification circuit 112. Here, the dimmer 113 may be selected from any one of ordinary dimmers, and therefore, a detailed description thereof will be omitted in the present embodiment.

The LED illumination unit 120 includes a plurality of LEDs 120-1 to 120-n, that is, a first LED 120-1 located at a shortest distance from a connection point with the power supply unit 110, And an n-th LED 120-n located at the longest distance from the power source 110, starting from the power source 120-1. The first LED 120-1 is electrically connected to the power supply unit 110 and all the LEDs 120-1 to 120-n included in the first LED 120-1 and the illumination unit 120 are connected to each other Connected in series.

The switching circuit unit 130 is individually connected to the output terminals of the LEDs 120-1 to 120-n forming the LED lighting unit 120. Each of the switching circuits 130 is connected to the corresponding LEDs 120-1 to 120- Lt; RTI ID = 0.0 > channel < / RTI >

The power supply voltage correction unit 140 is connected in parallel to the connection line between the power supply unit 110 and the first LEDs 120-1 of the LED lighting unit 120. The power supply voltage correction unit 140 includes a power supply unit 110, And outputs an adjustment signal of the current value supplied to the LED illumination unit 120 when the absolute value of the AC power input through the LED illumination unit 120 changes.

The reference voltage value input unit 150 detects the entire reference voltage value in the LED lighting driver circuit 100 and inputs it to the power supply voltage correction unit 140. That is, the entire reference voltage value in the LED lighting driver circuit 100 is input to the power supply voltage correction unit 140 through the reference voltage value input unit 150.

The reference voltage supply unit 160 individually applies the reference voltages REF1 to REFn to the switching circuit units 130 based on the signal input through the power supply voltage correction unit 140. [

The output value of the power supply voltage correction unit 140 is provided to the reference voltage supply unit 160 that generates the reference current or the reference voltage of the switching circuit unit 130, The current value of the supply current is controlled in conjunction with the output value of the power supply voltage correction unit 140. [

5 is a circuit diagram conceptually showing another example of an LED lighting driver circuit having a light amount compensation function according to the present invention. Referring to FIG. 5, a power supply voltage correction unit 140 includes a power supply unit 111 And the rectifying circuit 112 and receives the AC power of the power supply 110 as an input signal. A pair of resistors serially connected to the connection line of the power supply voltage correction unit 140 connected in parallel to the connection line between the power supply unit 111 and the rectification circuit 112 is provided, The connection line to the terminal 140 may be branched. In Fig. 5, the same reference numerals are used for the same components as those in Fig.

Hereinafter, an LED light driving circuit 100 (hereinafter referred to as an LED light driving circuit) having a light amount compensation function when the power supply voltage changes according to an embodiment of the present invention will be described with reference to FIG. The LED lighting driver circuit 100 according to the present embodiment is similar in overall configuration to the LED lighting driver circuit described in FIG. 4, and therefore, the same reference numerals are used for the same components as those in FIG. 4, The description will be omitted.

The LED lighting circuit 100 according to an exemplary embodiment of the present invention includes a power supply unit 110, an LED illumination unit 120, a switching circuit unit 130, a power supply voltage correction unit 140, (150), and a reference voltage supply unit (160).

The power supply unit 110 and the LED lighting unit 120 have the same configuration as the LED lighting driving circuit shown in FIG.

The switching circuit unit 130 is individually connected to the output terminals of the LEDs 121 to 124 forming the LED lighting unit 120. In other words, the switching circuit unit 130 has a plurality of configurations that are the same as the number of LEDs.

Here, the common ground resistor 133, to which the plurality of switching circuit portions 130 are commonly grounded, is further included in the LED light driving circuit 100.

The switching circuit unit 130 includes a switching device 131 and a comparator 132. The switching device 131 is connected to the LED output terminal of the LED driving unit 120 and is connected to the common grounding resistor 133, The comparator 132 compares the reference voltage of the reference voltage supply unit 160 with the common voltage of the common ground resistance 133. The switching element 130 is connected to either the first current path connected to the LEDs 121 to 124 of the LED driver 120 or the second current path connected to the common ground resistor 133 according to the output of the comparator 132 And the common voltage of the common ground resistor 133 is varied. In this embodiment, the switching element 131 is a field effect transistor (MOS) having a drain connected to the LED output terminal of the LED driving part 120, a source connected to the common ground resistance 133, and a gate connected to the comparator 132 FET), but the present invention is not limited thereto.

The power supply voltage correction unit 140 includes an average voltage value calculation unit 141, an instantaneous voltage value detection unit 142, an operation unit 143, and a reference voltage value correction unit 144. The power supply voltage correction unit 140 may further include a voltage adjustment unit 145.

The voltage adjusting unit 145 may be installed in a connection line between either or both of the average voltage value calculating unit 141 and the instantaneous voltage value detecting unit 142 and the power source unit 110. [ The voltage adjusting unit 145 functions to lower the AC power input through the power supply unit 110 to the driving voltage of the LED lighting driving circuit 100. In this embodiment, the voltage adjusting unit 145 is connected in series to the connection line between the power supply unit 110 and the average voltage value calculating unit 141, and the connection line between the voltage adjusting unit 145 and the average voltage value calculating unit 141 The instantaneous voltage value detector 142 is connected in parallel to the first embodiment, but the present invention is not limited thereto.

The average voltage value calculation unit 141 calculates the average voltage value V _PL by averaging the magnitude of the power source voltage based on the waveform inputted through the voltage adjustment unit 145. In the present embodiment, the average voltage value calculator 141 calculates the average voltage value V _PL by averaging the total magnitude of the input power supply voltage for one hour or more on the basis of the pulse waveform. In addition,

The instantaneous voltage value detector 142 detects the instantaneous voltage value V _PS when the magnitude of the power source voltage of the waveform reference input through the voltage adjuster 145 is instantaneously changed.

The calculating unit 143 receives the output voltage values of the average voltage value calculating unit 141 and the instantaneous voltage value detecting unit 142 and calculates the difference between the two voltage values V _PL and V _PS . And outputs K (V _PS -V _PL ) which is a value obtained by multiplying the gain K by the reference voltage value correcting unit 144. Here, the specific gain K corresponds to a compensation gain for adjusting the degree of correction of the voltage value (or current value).

The reference voltage value correction unit 144 subtracts the output voltage value of the operation unit 143 from the total reference voltage value in the LED illumination driving circuit 100 to obtain a correction value V _{COMP_REF} = V _REFO -K (V _PS- V _PL ), and then inputs the correction value of the reference voltage value thus calculated to the reference voltage supply unit 160. Here, the entire reference voltage value V _{REFO in the} LED drive circuit 100 is input from the reference voltage value input unit 150 to the reference voltage value correction unit 144.

The reference voltage supply unit 160 applies the reference voltages REF1 to REF4 to the switching circuit units 130 based on the signal input from the reference voltage value correction unit 144. [

The average voltage value V _PL of the average voltage value calculating unit 141 and the instantaneous voltage value of the instantaneous voltage value detecting unit 142 V _PS) is the same, the value of the current supplied to the switching circuit 130 follows the LED lighting driving circuit 100, the reference voltage of the total (V _REFO), has the instantaneous voltage value (V _PS if the power is shaken) - mean The current value for the switching circuit part 130 is corrected according to the value of the voltage value V _PL .

7 is a circuit diagram conceptually showing another example of an LED lighting driver circuit having a light amount compensation function when a power supply voltage is changed according to an embodiment of the present invention. As shown in FIG. 7, The voltage adjusting unit 145 is connected in parallel to the connection line between the power supply unit 111 and the rectifying circuit 112 to receive the AC power of the power supply unit 110 as an input signal. Here, a pair of resistors connected in series are provided in the connection line of the voltage regulator 145 connected in parallel to the connection line between the power supply unit 111 and the rectifier circuit 112, and the voltage regulator 145, Lt; RTI ID = 0.0 > line. ≪ / RTI >

The LED light driving circuit having the light amount compensating function in the power supply voltage change of FIG. 7 is entirely the same as that of FIG. 6 except that the circuit configurations of FIG. 6 are shown as a block diagram. Therefore, detailed description of the block configurations of FIG. 7 is omitted.

FIG. 8 is a diagram illustrating a change in current waveform according to a power supply change in an LED lighting driver circuit having a light amount compensation function when a power supply voltage changes according to embodiments of the present invention, wherein (a) (B) corresponds to the case where there is a dimmer.

As it can be seen, while in the event of an abrupt change in size of the power supply current waveform is widened in width (L _1, L ₂₎ and its size can be confirmed that becomes smaller as H ₁ (or H _2). That is, when the power source voltage suddenly increases, the current range of the current source is reduced instead of the maximum operating range of the current driving current source, so that the amount of light of the LED lighting unit is kept similar.

Also, if the value of the AC power source suddenly decreases, the magnitude of current of the current source increases, and it is easy to estimate that the amount of light of the LED illumination unit is maintained at a similar level.

As can be seen from the embodiments of FIGS. 4 to 8, the LED light driving circuit having the light amount compensation function when the power supply voltage changes according to the present invention is characterized in that, in the LED lighting driving circuit of the AC direct type, Even if the absolute value changes, the change of the final LED emission amount is minimized, and accordingly, the LED illumination can maintain and exhibit stable lighting function without causing flickering or shaking of the light even in an unstable power state.

The present invention is not limited to the above-described embodiment, but may be applied to other types of light emitting devices such as a light emitting diode It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

100: LED light driving circuit 110:
111: power supply unit 112: rectifier circuit
113: dimmer 120: LED lighting part
120-1: first LED 120-2: second LED
120-3: Third LED 120-n: Control LED
130: switching circuit unit 131: switching element
132: comparator 133: common ground resistance
140: Power supply voltage correction unit 141: Average voltage value calculation unit
142: instantaneous voltage value detector 143:
144: Reference voltage value correcting unit 145: Voltage adjusting unit
150: reference voltage value input unit 160: reference voltage supply unit

Claims (12)

A power supply unit including a power supply unit to which an external AC power is supplied and a rectification circuit of an AC power supply to be applied through the power supply unit;
An LED lighting unit including an n-th LED located at a longest distance from a power source, the first LED being located at a shortest distance from a connection point with the power source unit, the first LED being connected to the power source unit and each LED being connected in series;
A plurality of switching circuit units individually connected to output terminals of the LEDs forming the LED illumination unit to form current supply channels for the LEDs;
An average voltage value calculation unit connected in parallel to a connection line between the power supply unit and the first LED, an instantaneous voltage value detection unit connected in parallel to a connection line between the power supply unit and the first LED, And an output voltage value of the operation unit is subtracted from the total reference voltage value in the LED lighting driving circuit to output a reference voltage value And a reference voltage value correcting unit for inputting the correction value to the reference voltage supplying unit.
And a reference voltage supply unit for applying a reference voltage to each of the switching circuit units based on a signal input from the power supply voltage correction unit. The method according to claim 1,
Wherein the power supply further comprises a dimmer connected to the power supply and adapted to receive an AC voltage and apply an output voltage to the rectifier circuit. delete The method according to claim 1,
The power supply voltage correcting unit may be configured to reduce the AC power input to the connection line between any one or both of the average voltage value calculating unit and the instantaneous voltage value detecting unit and the power supply unit to the driving voltage of the LED lighting driving circuit And a voltage adjusting unit for adjusting the amount of power supplied to the light source. 5. The method of claim 4,
Wherein the voltage adjusting unit is connected in series to a connection line between the power supply unit and the mean voltage value calculating unit and the instantaneous voltage value detecting unit is connected in parallel to a connection line between the voltage adjusting unit and the mean voltage value calculating unit. LED lighting driving circuit with light amount compensation function. 6. The method of claim 5,
Wherein the average voltage value calculating unit calculates an average voltage value by averaging a power supply voltage level of the waveform reference input through the voltage adjusting unit. The method according to claim 6,
Wherein the average voltage value calculating unit calculates an average voltage value by averaging the total magnitude of the input power supply voltage for one hour or more based on a pulse waveform reference. 6. The method of claim 5,
Wherein the voltage regulator is connected in parallel to a connection line between the rectifying circuit and the first LED to receive an AC power of the power supply as an input signal or to be connected in parallel to a connection line between the power supply and the rectifier circuit, And a light amount compensating function at the time of a power supply voltage change. 9. The method of claim 8,
Wherein a pair of resistors connected in series is connected to a connection line of the voltage regulator connected in parallel to a connection line between the power supply unit and the rectification circuit so that the connection line to the voltage regulator is branched between the pair of resistors An LED light driving circuit having a light amount compensation function when the power supply voltage changes. 5. The method of claim 4,
Wherein the instantaneous voltage value detector detects an instantaneous voltage value of a voltage level of the waveform when the magnitude of the power source voltage of the waveform reference inputted through the voltage adjuster changes instantaneously, LED lighting driving circuit. The method according to claim 1,
Further comprising a common ground resistance to which the switching circuit portions are commonly grounded,
The switching circuit includes a switching element connected to the LED output terminal of the LED driving part and connected to the common ground resistance, and a comparator for comparing a reference voltage of the reference voltage supplying part with a common voltage of the common grounding resistance, Wherein the switching element switches to either the first current path connected to the LED of the LED driving part and the second current path connected to the common ground resistance in accordance with the output of the comparator, And the voltage of the power source voltage is varied. 12. The method of claim 11,
Wherein the switching element is a field effect transistor (MOS FET) having a drain connected to an LED output terminal of the LED driving unit, a source connected to the common ground resistance, and a gate connected to the comparator. LED lighting driving circuit with function.

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