CN101646290A - Led drive circuit - Google Patents

Abstract

An LED drive circuit that drives an LED is provided with: a rectifying circuit that converts an alternating voltage into a pulsating current; a constant current circuit; and an over-temperature protection portion that limits an output of the constant current circuit, wherein the LED and the constant current circuit are connected in series on an output side of the rectifying circuit.

Description

Led drive circuit

Technical field

The present invention relates to the led drive circuit of driving LED (light-emitting diode).

Background technology

LED is because of its low-power consumption and feature of long life, in more and more wide field---be not only display unit and in lighting apparatus etc.---is applied.In lighting apparatus, use a plurality of LED to obtain required illumination.

Then its life-span can shorten LED if receive the electric current that surpasses load current value.Therefore, LED need drive with constant current, the electric current restriction perhaps is set makes that not having the electric current that surpasses pre-sizing flows through wherein.

General lighting apparatus uses commercial AC 100V power supply mostly.Thereby, if use the LED lighting apparatus to replace incandescent lamp etc., then preferably should as lighting apparatus such, the LED lighting apparatus is arranged to also use commercial AC 100V power supply.

The example (referring to JP-A-2000-260578) of the configuration of the conventional led drive circuit that can in the LED lighting apparatus, use shown in Figure 20.Conventional led drive circuit shown in Figure 20 is with constant current driven LED, and is provided with: bridge diode 2; Resistance R 20_2; And constant-current circuit A20.Constant-current circuit A20 is provided with: NPN transistor Q20; Resistance R 20_1; And Zener diode ZD20.

The input side of bridge diode 2 is connected to commercial AC 100V power supply 1, the outlet side of bridge diode 2 is connected to led module 3, this led module 3 is the modules with a plurality of LED coupled in series, promptly, cathode output end that is had from bridge diode 2, reaches resistance R 20_1 and is connected in series in proper order with this led module 3, NPN transistor Q20.The end of resistance R 20_2 is connected to the tie point that bridge diode 2 and led module 3 link together.The base stage of NPN transistor Q20 is connected to the other end of resistance R 20_2 and the negative electrode of Zener diode ZD20.The anode of Zener diode ZD20 is connected to the tie point that resistance R 20_1 and bridge diode 2 link together.

Utilize this configuration, the AC voltage of exporting from commercial AC100V power supply 1 carries out full-wave rectification by bridge diode 2, thereby obtains the pulsating voltage that its peak value is about 141V.In constant-current circuit A20, the base potential of NPN transistor Q20 is by the Zener voltage V of Zener diode ZD20 _ZAnd become constant by clamper.Therefore, be V if make the base stage of NPN transistor Q20 and the voltage between the emitter _BEO20, then the both end voltage of resistance R 20_1 is represented as (V _Z-V _BEQ20), and if to make the resistance value of resistance R 20_1 be R _{20_1}, the electric current that then flows through resistance R 20_1 is represented as (V _Z-V _BEQ20)/R _{20_1}, the electric current that resistance R 20_1 is flow through in this expression is constant.That is, the electric current that flows through led module 3 is constant, and is represented as (V _Z-V _BEQ20)/R _{20_1}

Usually, the voltage of Zener diode presents positive temperature characterisitic (promptly, along with temperature raises, voltage rises), and the voltage between transistorized base stage and the emitter presents negative temperature characterisitic (that is, along with temperature raises, voltage descends), and resistance presents positive temperature characterisitic (that is, along with temperature raises, resistance value rises).Therefore, constant-current circuit A1 presents positive temperature characterisitic (that is, along with temperature raises, constant current value rises).Thereby in conventional led drive circuit shown in Figure 20, the electric current that the temperature rising may cause dropping on outside the predetermined value flow among the LED.

In conventional led drive circuit shown in Figure 20, all be not provided for temperature at led module 3 or led drive circuit self rise carry out overtemperature protection under the condition with higher components and parts or circuit.Thereby, if if its ambient temperature rises highly singularly or the anode terminal of led module 3 and cathode terminal between be short-circuited, then the worst led module 3 or the led drive circuit of may causing damages.And if apply excessive load, then incandescent lamp will lose efficacy and its filament disconnection with open circuit mode, and each free semiconductor components and devices of led module 3 and led drive circuit constitutes, and will lose efficacy with short-circuit mode.Therefore, led drive circuit must be made for,, also can not smolder or on fire even at led module 3 or constitute under the worst condition that arbitrary components and parts of led drive circuit are short-circuited.

The protection device and the temperature sensing device that have multiple general use are such as POSISTOR (semistor) ((registered trade mark) made by Japanese Murata Manufacturing Co. Ltd.).Yet, these devices all have lower rated voltage and lower rated power, and do not generating constant DC voltage, the substitute is source power supply is connected directly under led drive circuit and the situation with the pulsating current driving LED, its application is restricted.

Summary of the invention

The object of the present invention is to provide with the pulsating current driving LED and have the led drive circuit of overheat protective function.

To achieve these goals, led drive circuit driving LED of the present invention, and comprise: the rectification circuit that alternating voltage is converted to pulsating voltage; Constant-current circuit; And the overtemperature protection portion that the output of constant-current circuit is limited, wherein LED and constant-current circuit are connected in series on the outlet side of rectification circuit.

And this overtemperature protection portion can comprise: the PNP transistor; And resistance, this resistance has negative temperature coefficient, and is arranged between transistorized base stage of PNP and the emitter.And the transistorized emitter and collector of PNP can be connected to the path of circulate among from the constant current of constant-current circuit output.In either case; for example; overtemperature protection portion also can comprise constant-current source; this constant-current source is connected in series with the resistance with negative temperature coefficient, and wherein the magnitude of voltage between transistorized base stage of PNP and the emitter is the product that multiplies each other and obtain by with the constant current value of constant-current source and the resistance value with resistance of negative temperature coefficient.Perhaps this overtemperature protection portion also can comprise: resistive element; this resistive element is connected in series with the resistance with negative temperature coefficient, and wherein the magnitude of voltage between transistorized base stage of PNP and the emitter is the product that current value and the resistance value with resistance of negative temperature coefficient of the electric current by will flowing through resistance with negative temperature coefficient and resistive element multiplies each other and obtain.

Perhaps, this overtemperature protection portion can comprise: NPN transistor; And resistance, this resistance has negative temperature coefficient, and is arranged between the base stage and emitter of NPN transistor, and wherein the emitter and collector of NPN transistor is connected to the path of circulate among from the constant current of constant-current circuit output.

And this led drive circuit also can comprise switching circuit, and this switching circuit switches the conducting and the disconnection of constant-current circuit, and wherein LED, constant-current circuit and switching circuit are connected in series on the outlet side of rectification circuit, and overtemperature protection portion control switch circuit.In this case, for example, this overtemperature protection portion can comprise: bipolar transistor, and this bipolar transistor is presented bias current to the control terminal of switching circuit; And resistance, this resistance has negative temperature coefficient, and the one end is connected to the base stage of bipolar transistor, and wherein the base stage of bipolar transistor and the magnitude of voltage between the emitter change according to the resistance value with resistance of negative temperature coefficient.Perhaps, this overtemperature protection portion can comprise: NPN transistor, and this NPN transistor will be pulled out to the bias current that the control terminal of switching circuit is presented; And resistance, this resistance has positive temperature coefficient, and the one end is connected to the base stage of NPN transistor, and wherein the base stage of NPN transistor and the magnitude of voltage between the emitter change according to the resistance value with resistance of positive temperature coefficient.And; this overtemperature protection portion also can comprise: constant-current source; this constant-current source is connected in series with the resistance that has the resistance of negative temperature coefficient or have a positive temperature coefficient, wherein the base stage of bipolar transistor or NPN transistor and the magnitude of voltage between the emitter be by with the constant current value of constant-current source with have the resistance of negative temperature coefficient or have the product that the resistance value of the resistance of positive temperature coefficient multiplies each other and obtains.Perhaps; this overtemperature protection portion also can comprise resistive element; this resistive element is connected in series with the resistance that has the resistance of negative temperature coefficient or have a positive temperature coefficient, wherein the base stage of bipolar transistor or NPN transistor and the magnitude of voltage between the emitter be by will flow through resistance with negative temperature coefficient or have the resistance of positive temperature coefficient and the value of the electric current of resistive element with have the resistance of negative temperature coefficient or have the product that the resistance value of the resistance of positive temperature coefficient multiplies each other and obtains.

Perhaps, in drive circuit of the present invention, this overtemperature protection portion can comprise: NPN transistor, and this NPN transistor will be pulled out to the bias current that constant-current circuit is presented; And resistance, this resistance has positive temperature coefficient, and is arranged between the base stage and emitter of NPN transistor.And; for example; this overtemperature protection portion also can comprise: constant-current source; this constant-current source is connected in series with the resistance with positive temperature coefficient, and wherein the base stage of NPN transistor and the magnitude of voltage between the emitter are the products that multiplies each other and obtain by with the constant current value of constant-current source and the resistance value with resistance of positive temperature coefficient.Perhaps; this overtemperature protection portion also can comprise: resistive element; this resistive element is connected in series with the resistance with positive temperature coefficient, and wherein the base stage of NPN transistor and the magnitude of voltage between the emitter are the products that value and the resistance value with resistance of positive temperature coefficient of the electric current by will flowing through resistance with positive temperature coefficient and resistive element multiplies each other and obtain.In either case; this overtemperature protection portion also can comprise: another resistance; this another resistance has positive temperature coefficient, and is arranged with the resistance branch with positive temperature coefficient, and another resistance that wherein has positive temperature coefficient is arranged on to constant-current circuit to be presented on the path of bias current.

Perhaps, in drive circuit of the present invention, this overtemperature protection portion can comprise: npn bipolar transistor, and this npn bipolar transistor is presented bias current to the bias current terminal of constant-current circuit; Control is with the npn bipolar transistor and first constant-current source, and this control is connected to the base stage of npn bipolar transistor respectively with the npn bipolar transistor and first constant-current source, and is used to control bias current; Resistance, this resistance has positive temperature coefficient, and the one end is connected to the base stage of control with NPN transistor; And second constant-current source, this second constant-current source is connected in series with the resistance with positive temperature coefficient, and wherein control is by with the constant current value of second constant-current source and have the product that the resistance value of the resistance of positive temperature coefficient multiplies each other and obtains with the base stage of NPN transistor and the magnitude of voltage between the emitter.Perhaps, overtemperature protection portion can comprise: npn bipolar transistor, and this npn bipolar transistor is presented bias current to the bias current terminal of constant-current circuit; Control is connected to the base stage of npn bipolar transistor with npn bipolar transistor and resistive element, this control respectively with npn bipolar transistor and resistive element, and is used to control bias current; Resistance, this resistance has positive temperature coefficient, and the one end is connected to the base stage of control with NPN transistor; And constant-current source, this constant-current source is connected in series with the resistance with positive temperature coefficient, and wherein control is by with the constant current value of constant-current source and have the product that the resistance value of the resistance of positive temperature coefficient multiplies each other and obtains with the base stage of NPN transistor and the magnitude of voltage between the emitter.Perhaps, this overtemperature protection portion can comprise: npn bipolar transistor, and this npn bipolar transistor is presented bias current to the bias current terminal of constant-current circuit; Control is with the npn bipolar transistor and first resistive element, and this control is connected to the base stage of npn bipolar transistor respectively with the npn bipolar transistor and first resistive element, and is used to control bias current; Resistance, this resistance has positive temperature coefficient, and the one end is connected to the base stage of control with npn bipolar transistor; And second resistive element, this second resistive element is connected in series with the resistance with positive temperature coefficient, and wherein control is the product that the value of the electric current by will flowing through the resistance with positive temperature coefficient and second resistive element and the resistance value with resistance of positive temperature coefficient multiply each other and obtain with the base stage of NPN transistor and the magnitude of voltage between the emitter.

And for example, this constant-current circuit can comprise: first resistance; Zener diode; And first bipolar transistor, the emitter of this first bipolar transistor is connected to an end of first resistance, and the base stage of this first bipolar transistor is connected to an end of Zener diode.Perhaps, this constant-current circuit can comprise: first bipolar transistor; Second bipolar transistor; First resistance, an end of this first resistance is connected to the base stage of second bipolar transistor; And second resistance, this second resistance is arranged between the base stage and emitter of first bipolar transistor, wherein the base stage of the collector electrode of first bipolar transistor and second bipolar transistor links together, and the emitter of the base stage of first bipolar transistor and second bipolar transistor links together.

And for example, this switching circuit can comprise: thyristor or bidirectional triode thyristor; And first resistance, this first resistance is arranged between the gate pole and negative electrode of thyristor or bidirectional triode thyristor.

And, comprise also that at led drive circuit switching circuit, this switching circuit switch under the situation of the conducting of constant-current circuit and disconnection, wherein LED, constant-current circuit and switching circuit are connected in series on the outlet side of rectification circuit, thereby overtemperature protection portion control switch circuit, this switching circuit comprises: thyristor or two-way one pole thyristor; And first resistance, this first resistance is arranged between the gate pole and negative electrode of thyristor or bidirectional triode thyristor, this overtemperature protection portion can comprise: resistance, this resistance has positive temperature coefficient, and is arranged on the path that is used for presenting to the gate pole of thyristor or bidirectional triode thyristor bias current; And resistive element, this resistive element is arranged between the cathode output end of the gate pole of thyristor or bidirectional triode thyristor and rectification circuit.And this overtemperature protection portion also can comprise: electric capacity, this electric capacity and resistive element are connected in parallel.

And, comprise that at led drive circuit switching circuit, this switching circuit switch under the situation of the conducting of constant-current circuit and disconnection, wherein LED, constant-current circuit and switching circuit are connected in series on the outlet side of rectification circuit, thereby overtemperature protection portion control switch circuit, switching circuit comprises: thyristor or bidirectional triode thyristor; And first resistance, this first resistance is arranged between the gate pole and negative electrode of thyristor or bidirectional triode thyristor, this overtemperature protection portion can comprise: resistance, and this resistance has positive temperature coefficient, and the one end is connected to the gate pole of thyristor or bidirectional triode thyristor; And resistive element, this resistive element is arranged between the cathode output end of the other end of the resistance with positive temperature coefficient and rectification circuit.And; this overtemperature protection portion also can comprise: another resistance; this another resistance has positive temperature coefficient; and be arranged with the resistance branch with positive temperature coefficient, another resistance that wherein has positive temperature coefficient is arranged on to the gate pole of thyristor or bidirectional triode thyristor to be presented on the path of bias current.

And, when constant-current circuit reaches predetermined temperature or when higher, this overtemperature protection portion can limit the output of constant-current circuit.

And, when led module reaches predetermined temperature or when higher, this overtemperature protection portion can limit the output of constant-current circuit.

Description of drawings

Fig. 1 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the first embodiment of the present invention.

Fig. 2 is the diagrammatic sketch that the configuration of led drive circuit according to a second embodiment of the present invention is shown.

Fig. 3 is the diagrammatic sketch of configuration that the led drive circuit of a third embodiment in accordance with the invention is shown.

Fig. 4 is the diagrammatic sketch of configuration that the led drive circuit of a fourth embodiment in accordance with the invention is shown.

Fig. 5 is the diagrammatic sketch that the configuration of led drive circuit according to a fifth embodiment of the invention is shown.

Fig. 6 is the diagrammatic sketch that the configuration of led drive circuit according to a sixth embodiment of the invention is shown.

Fig. 7 A is the diagrammatic sketch of example that the configuration of led drive circuit according to a seventh embodiment of the invention is shown.

Fig. 7 B is the diagrammatic sketch of another example that the above-mentioned configuration of led drive circuit according to a seventh embodiment of the invention is shown.

Fig. 8 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the eighth embodiment of the present invention.

Fig. 9 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the ninth embodiment of the present invention.

Figure 10 is the diagrammatic sketch of example that the configuration of constant-current circuit is shown.

Figure 11 is the diagrammatic sketch of another example that the configuration of constant-current circuit is shown.

Figure 12 is the diagrammatic sketch of another example that the configuration of constant-current circuit is shown.

Figure 13 is the diagrammatic sketch of another example that the configuration of constant-current circuit is shown.

Figure 14 is the diagrammatic sketch of example that the configuration of switching circuit is shown.

Figure 15 is the diagrammatic sketch of another example that the configuration of switching circuit is shown.

Figure 16 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the tenth embodiment of the present invention.

Figure 17 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the 11st embodiment of the present invention.

Figure 18 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the 12nd embodiment of the present invention.

Figure 19 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the 13rd embodiment of the present invention.

Figure 20 is the diagrammatic sketch that conventional led drive circuit is shown.

Figure 21 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the 14th embodiment of the present invention.

Figure 22 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the 15th embodiment of the present invention.

Figure 23 is the diagrammatic sketch that illustrates according to the configuration of the led drive circuit of the 16th embodiment of the present invention.

Embodiment

Below with reference to accompanying drawing description each embodiment according to led drive circuit of the present invention.Led drive circuit according to the present invention is used to lighting apparatus, electronic display system etc.

＜the first embodiment 〉

Shown in Fig. 1 according to the configuration of the led drive circuit of the first embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 1 comprises: bridge diode 2; Constant-current circuit A1 and B1; PNP transistor Q1; Resistance R 1; And such as the negative temperature coefficient resister RN1 (hereinafter referred to as " NTC resistance R N1 ") of NTC thermistor.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A1 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A1 is connected to another output of bridge diode 2.The emitter of PNP transistor Q1 is connected to the negative electrode of led module 3, and the collector electrode of PNP transistor Q1 is connected to the bias current terminal T3 of constant-current circuit A1 by resistance R 1.And NTC resistance R N1 is arranged between the base stage and emitter of PNP transistor Q1, and constant-current circuit B1 is arranged between another output of the base stage of PNP transistor Q1 and bridge diode 2.

PNP transistor Q1 is driven by constant-current circuit B1, and presents bias current to the bias current terminal T3 of constant-current circuit A1.In the led drive circuit of present embodiment shown in Figure 1, by to limiting to the bias current that the bias current terminal T3 of constant-current circuit A1 presents by resistance R 1 by PNP transistor Q1, thereby the output of restriction constant-current circuit A1, thereby this constant-current circuit A1 presents constant current driving LED module 3 to led module 3.Utilize this design, the load of PNP transistor Q1 reduces, thereby smaller transistor is used for PNP transistor Q1 becomes possibility, to limit the output of constant-current circuit A1.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A1) set at constant-current circuit A1.

In the led drive circuit of present embodiment shown in Figure 1, along with ambient temperature rises, the resistance value of NTC resistance R N1 reduces, and causes the base stage of PNP transistor Q1 and the voltage between the emitter to reduce.Therefore, the bias current of presenting to the bias current terminal T3 of constant-current circuit A1 reduces, and consequently the constant current value of constant-current circuit A1 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 1 reaches predefined specified level or when higher, PNP transistor Q1 is placed in off-state, does not consequently present bias current to the bias current terminal T3 of constant-current circuit A1.Therefore, constant-current circuit A1 is placed in off-state.

NTC resistance R N1 is being arranged under the base stage and the situation between the emitter of PNP transistor Q1, by setting its resistance value for suitable value, for NTC resistance R N1, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And constant-current circuit B1 presents base current to PNP transistor Q1, and its constant current value equals the 1/h of the bias current presented to the bias current terminal T3 of constant-current circuit A1 _FE(h here _FEBe the h parameter of PNP transistor Q1).The overtemperature protection operation that will cause PNP transistor Q1 to be in off-state is taken into account; by setting its constant current value for suitable value; for constant-current circuit B1, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

＜the second embodiment 〉

According to a second embodiment of the present invention the configuration of led drive circuit shown in Fig. 2.The led drive circuit of present embodiment shown in Figure 2 is provided with: bridge diode 2; Constant-current circuit A2 and B2; PNP transistor Q2; Resistance R 2; And negative temperature coefficient resister (hereinafter referred to as " NTC resistance ") RN2.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The negative electrode of led module 3 is connected to the emitter of PNP transistor Q2.The constant current terminal T1 of constant-current circuit A2 is connected to the collector electrode of PNP transistor Q2, and the constant current terminal T2 of constant-current circuit A2 is connected to another output of bridge diode 2.And the collector electrode of PNP transistor Q2 is connected to the bias current terminal T3 of constant-current circuit A2 by resistance R 2.And NTC resistance R N2 is arranged between the base stage and emitter of PNP transistor Q2, and constant-current circuit B2 is arranged between another output of the base stage of PNP transistor Q2 and bridge diode 2.

PNP transistor Q2 is driven by constant-current circuit B2.Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A2) set at constant-current circuit A2.

In the led drive circuit of present embodiment shown in Figure 2, along with ambient temperature rises, the resistance value of NTC resistance R N2 reduces, and causes the base stage of PNP transistor Q2 and the voltage between the emitter to reduce.Thereby the constant current value of constant-current circuit A2 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 2 reaches predefined specified level or when higher, PNP transistor Q2 is placed in off-state, thereby constant-current circuit A2 is placed in off-state.

NTC resistance R N2 is being arranged under the base stage and the situation between the emitter of PNP transistor Q2, by setting its resistance value for suitable value, for NTC resistance R N2, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And constant-current circuit B2 presents base current to PNP transistor Q2, and its constant current value equals the 1/h of the output current of constant-current circuit A2 _FE(h here _FEBe the h parameter of PNP transistor Q2).The overtemperature protection operation that will cause PNP transistor Q2 to be in off-state is taken into account; by setting its constant current value for suitable value; for constant-current circuit B2, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

＜the three embodiment 〉

The configuration of the led drive circuit of a third embodiment in accordance with the invention shown in Fig. 3.The led drive circuit of present embodiment shown in Figure 3 is provided with: bridge diode 2; Constant-current circuit A3; PNP transistor Q3; Resistance R 3_1 and R3_2; And negative temperature coefficient resister (hereinafter referred to as " NTC resistance ") RN3.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A3 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A3 is connected to another output of bridge diode 2.And the emitter of PNP transistor Q3 is connected to the negative electrode of led module 3, and the collector electrode of PNP transistor Q3 is connected to the bias current terminal T3 of constant-current circuit A3 by resistance R 3_1.And NTC resistance R N3 is arranged between the base stage and emitter of PNP transistor Q3, and resistance R 3_2 is arranged between another output of the base stage of PNP transistor Q3 and bridge diode 2.

PNP transistor Q3 is driven by NTC resistance R N3 and resistance R 3_2, and presents bias current to the bias current terminal T3 of constant-current circuit A3.In the led drive circuit of present embodiment shown in Figure 3, by to limiting to the bias current that the bias current terminal T3 of constant-current circuit A3 presents by resistance R 3_1 by PNP transistor Q3, thereby the output of restriction constant-current circuit A3, thereby this constant-current circuit A3 presents constant current driving LED module 3 to led module 3.Utilize this design, the load on the PNP transistor Q3 reduces, thereby smaller transistor is used for PNP transistor Q3 becomes possibility, to limit the output of constant-current circuit A3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A3) set at constant-current circuit A3.

In the led drive circuit of present embodiment shown in Figure 3, along with ambient temperature rises, the resistance value of NTC resistance R N3 reduces, and causes the base stage of PNP transistor Q3 and the voltage between the emitter to reduce.Therefore, the bias current of presenting to the bias current terminal T3 of constant-current circuit A3 reduces, and consequently the constant current value of constant-current circuit A3 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 3 reaches predefined specified level or when higher, PNP transistor Q3 is placed in off-state, does not consequently present bias current to the bias current terminal T3 of constant-current circuit A3.Therefore, constant-current circuit A3 is placed in off-state.

NTC resistance R N3 is being arranged under the base stage and the situation between the emitter of PNP transistor Q3, by setting its resistance value for suitable value, for NTC resistance R N3, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And resistance R 3_2 presents base current to PNP transistor Q3, and the electric current that flows through resistance R 3_2 equals the 1/h of the bias current presented to the bias current terminal T3 of constant-current circuit A3 _FE(h here _FEBe the h parameter of PNP transistor Q3).The overtemperature protection operation that will cause PNP transistor Q3 to be in off-state is taken into account; set suitable value for by the current value that will flow through resistance R 3_2; for resistance R 3_2, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

Can with in the same manner configuration shown in Figure 2 is made amendment from the modification that Fig. 1 to Fig. 3 carried out.That is, constant-current circuit B2 can be replaced by the resistance with suitable resistance value.

＜the four embodiment 〉

The configuration of the led drive circuit of a fourth embodiment in accordance with the invention shown in Fig. 4.The led drive circuit of present embodiment shown in Figure 4 is provided with: bridge diode 2; Constant-current circuit A4; NPN transistor Q4; Resistance R 4_1 and R4_2; And negative temperature coefficient resister (below, be called " NTC resistance ") RN4.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A4 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A4 is connected to the collector electrode of NPN transistor Q4.The emitter of NPN transistor Q4 is connected to another output of bridge diode 2.And the negative electrode of led module 3 is connected to the bias current terminal T3 of constant-current circuit A4 by resistance R 4_1.And resistance R 4_2 is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q4, and NTC resistance R N4 is arranged between the base stage and emitter of NPN transistor Q4.

NPN transistor Q4 is driven by resistance R 4_2 and NTC resistance R N4.Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A4) set at constant-current circuit A4.

In the led drive circuit of present embodiment shown in Figure 4, along with ambient temperature rises, the resistance value of NTC resistance R N4 reduces, and causes the base stage of PNP transistor Q4 and the voltage between the emitter to reduce.Thereby the constant current value of constant-current circuit A4 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 4 reaches predefined specified level or when higher, NPN transistor Q4 is placed in off-state, thereby constant-current circuit A4 is placed in off-state.

NTC resistance R N4 is being arranged under the base stage and the situation between the emitter of NPN transistor Q4, by setting its resistance value for suitable value, for NTC resistance R N4, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And resistance R 4_2 presents base current to NPN transistor Q4, and the electric current that flows through resistance R 4_2 equals the 1/h of the output current of constant-current circuit A4 _FE(h here _FEBe the h parameter of NPN transistor Q4).The overtemperature protection operation that will cause NPN transistor Q4 to be in off-state is taken into account; become suitable value by the current settings that will flow through resistance Q4_2; for resistance R 4_2, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

＜the five embodiment 〉

According to a fifth embodiment of the invention the configuration of led drive circuit shown in Fig. 5.The led drive circuit of present embodiment shown in Figure 5 is provided with: bridge diode 2; Constant-current circuit A5 and B5; Switching circuit C5; Resistance R 5_1 and R5_2; NPN transistor Q5; And negative temperature coefficient resister (hereinafter referred to as " NTC resistance ") RN5.Switching circuit C5 is formed, make if the bias current of presenting to its control terminal T6 is equal to or greater than predetermined value, then the path between its contact terminal T4 and the contact terminal T5 becomes and conducts, and if the bias current of presenting to its control terminal T6 less than predetermined value, then the path between its contact terminal T4 and the contact terminal T5 becomes not conducting.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A5 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A5 is connected to the contact terminal T4 of switching circuit C5.The contact terminal T5 of switching circuit C5 is connected to another output of bridge diode 2.And the end of resistance R 5_1 is connected to the negative electrode of led module 3, and the other end of resistance R 5_1 is connected to the bias current terminal T3 of constant-current circuit A5 and the end of resistance R 5_2.The other end of resistance R 5_2 is connected to the collector electrode of NPN transistor Q5, and the emitter of NPNQ5 is connected to the control terminal T6 of switching circuit C5.And constant-current circuit B5 is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q5, and NTC resistance R N5 is arranged between another output of the base stage of NPN transistor Q5 and bridge diode 2.

NPN transistor Q5 is driven by constant-current circuit B5, and presents bias current to the control terminal T6 of switching circuit C5.In the led drive circuit of present embodiment shown in Figure 5, by the bias current of limit switch circuit C5, thus the output of restriction constant-current circuit A5, thus this constant-current circuit A5 presents constant current driving LED module 3 to led module 3.Utilize this design, the load of NPN transistor Q5 reduces, thereby smaller transistor is used for NPN transistor Q5 becomes possibility, to limit the output of constant-current circuit A5.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A5) set at constant-current circuit A5.

In the led drive circuit of present embodiment shown in Figure 5, along with ambient temperature rises, the resistance value of NTC resistance R N5 reduces, and causes the base stage of NPN transistor Q5 and the voltage between the emitter to reduce.Therefore, the bias current of presenting to the control terminal T6 of switching circuit C5 reduces, and consequently the constant current value of constant-current circuit A5 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 5 reaches predefined specified level or when higher, NPN transistor Q5 is placed in off-state, does not consequently present bias current to the control terminal T6 of switching circuit C5.Therefore, constant-current circuit A5 is placed in off-state.

Under the situation of the base stage that NTC resistance R N5 is connected to NPN transistor Q5,,, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong for NTC resistance R N5 by setting its resistance value for suitable value.

And constant-current circuit B5 presents base current to NPN transistor Q5, and its constant current value equals the 1/h of the bias current presented to the control terminal T6 of switching circuit C5 _FE(h here _FEBe the h parameter of NPN transistor Q5).The overtemperature protection operation that will cause NPN transistor Q5 to be in off-state is taken into account; by setting its constant current value for suitable value; for constant-current circuit B5, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

＜the six embodiment 〉

According to a sixth embodiment of the invention the configuration of led drive circuit shown in Fig. 6.The led drive circuit of present embodiment shown in Figure 6 is provided with: bridge diode 2; Constant-current circuit A6 and B6; Switching circuit C6; Resistance R 6_1 and R6_2; NPN transistor Q6; And such as the positive temperature coefficient resistor RP6 (hereinafter referred to as " PTC resistance R P6 ") of PTC thermistor.Switching circuit C6 is formed, make if the bias current of presenting to its control terminal T6 is equal to or greater than predetermined value, then the path between its contact terminal T4 and the contact terminal T5 becomes and conducts, less than predetermined value, then the path between its contact terminal T4 and the contact terminal T5 becomes not conducting as if the bias current of presenting to its control terminal T6.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A6 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A6 is connected to the contact terminal T4 of switching circuit C6.The contact terminal T5 of switching circuit C6 is connected to another output of bridge diode 2.And the end of resistance R 6_1 is connected to the negative electrode of led module 3, and the other end of resistance R 6_1 is connected to the bias current terminal T3 of constant-current circuit A6 and the end of resistance R 6_2.The other end of resistance R 6_2 is connected to the collector electrode of control terminal T6 and the NPN transistor Q6 of switching circuit C6, and the emitter of NPN transistor Q6 is connected to another output of bridge diode 2.And constant-current circuit B6 is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q6, and PTC resistance R P6 is arranged between the base stage and emitter of NPN transistor Q6.

To PTC resistance R P6 circulation electric current is arranged from constant-current circuit B6, and the resistance value of the constant current value of constant-current circuit B6 and PTC resistance R P6 set for make that NPN transistor Q6 remains on off-state at normal temperatures.And, bias current is fed to the control terminal T6 of switching circuit C6 by R6_1 and R6_2 from the negative electrode of led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A6) set at constant-current circuit A6.

In the led drive circuit of present embodiment shown in Figure 6, along with ambient temperature rises, the resistance value of PTC resistance R P6 increases, and causes the base stage of NPN transistor Q6 and the voltage between the emitter to increase.Therefore, NPN transistor Q6 makes the bias current of presenting to the control terminal T6 of switching circuit C6 reduce, and consequently the constant current value of constant-current circuit A6 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 6 reaches predefined specified level or when higher, all bias currents that NPN transistor Q6 will present to the control terminal T6 of switching circuit C6 are pulled out, and consequently do not present bias current to the control terminal T6 of switching circuit C6.Therefore, constant-current circuit A6 is placed in off-state.

In the led drive circuit of present embodiment shown in Figure 6, the bias current of presenting to switching circuit C6 by restriction, thereby the output of restriction constant-current circuit A6, thus this constant-current circuit A6 presents constant current driving LED module 3 to led module 3.Utilize this design, the load of NPN transistor Q6 reduces, thereby smaller transistor is used for NPN transistor Q6 becomes possibility, to limit the output of constant-current circuit A6.

PTC resistance R P6 is being arranged under the base stage and the situation between the emitter of NPN transistor Q6, by setting its resistance value for suitable value, for PTC resistance R P6, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And; constant-current circuit B6 presents base current to NPN transistor Q6; make NPN transistor Q6 when being placed in conducting state because of the overtemperature protection operation; all bias currents that to present to the control terminal T6 of switching circuit C6 are pulled out, as long as constant-current circuit B6 can present the 1/h that is equal to or greater than the bias current of presenting to the control terminal T6 of switching circuit Q6 _FE(h here _FEBe the h parameter of NPN transistor Q6) electric current get final product.Thereby, by setting its constant current value for suitable value,, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong for constant-current circuit B6.

＜the seven embodiment 〉

According to a seventh embodiment of the invention the example of configuration of led drive circuit shown in Fig. 7 A.The led drive circuit of present embodiment shown in Figure 7 is provided with: bridge diode 2; Constant-current circuit A7A; Switching circuit C7A; Resistance R 7_1A to R7_3A; NPN transistor Q7A; And positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP7A.Switching circuit C7A is formed, make if the bias current of presenting to its control terminal T6 is equal to or greater than predetermined value, then the path between its contact terminal T4 and the contact terminal T5 becomes and conducts, less than predetermined value, then the path between its contact terminal T4 and the contact terminal T5 becomes not conducting as if the bias current of presenting to its control terminal T6.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A7A is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A7A is connected to the contact terminal T4 of switching circuit C7A.The contact terminal T5 of switching circuit C7A is connected to another output of bridge diode 2.And the end of resistance R 7_1A is connected to the negative electrode of led module 3, and the other end of resistance R 7_1A is connected to the bias current terminal T3 of constant-current circuit A7A and the end of resistance R 7_2A.The other end of resistance R 7_2A is connected to the collector electrode of control terminal T6 and the NPN transistor Q7A of switching circuit C7A, and the emitter of NPN transistor Q7A is connected to another output of bridge diode 2.And resistance R 7_3A is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q7A, and PTC resistance R P7A is arranged between the base stage and emitter of NPN transistor Q7A.

To PTC resistance R P7A circulation electric current is arranged from resistance R 7_3A, and the resistance value of resistance R 7_3A and PTC resistance R P7A set for make that NPN transistor Q7A remains on off-state at normal temperatures.And, bias current is fed to the control terminal T6 of switching circuit C7A by R7_1A and R7_2A from the negative electrode of led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A7A) set at constant-current circuit A7A.

In the led drive circuit of the present embodiment shown in Fig. 7 A, along with ambient temperature rises, the resistance value of PTC resistance R P7A increases, and causes the base stage of NPN transistor Q7A and the voltage between the emitter to increase.Therefore, NPN transistor Q7A makes the bias current of presenting to the control terminal T6 of switching circuit C7A reduce, and consequently the constant current value of constant-current circuit A7A is restricted.When the ambient temperature of the led drive circuit of the present embodiment shown in Fig. 7 A reaches predefined specified level or when higher, all bias currents that NPN transistor Q7A will present to the control terminal T6 of switching circuit C7A are pulled out, and consequently do not present bias current to the control terminal T6 of switching circuit C7A.Therefore, constant-current circuit A7A is placed in off-state.

In the led drive circuit of present embodiment shown in Figure 7, by the bias current of limit switch circuit C7A, thus the output of restriction constant-current circuit A7A, thus this constant-current circuit A7A presents constant current driving LED module 3 to led module 3.Utilize this design, the load of NPN transistor Q7A reduces, thereby smaller transistor is used for NPN transistor Q7A becomes possibility, to limit the output of constant-current circuit A7A.

PTC resistance R P7A is being arranged under the base stage and the situation between the emitter of NPN transistor Q7A, by setting its resistance value for suitable value, for PTC resistance R P7A, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And; resistance R 7_3A presents base current to NPN transistor Q7A; make NPN transistor Q7A when being placed in conducting state because of the overtemperature protection operation; all bias currents that to present to the control terminal T6 of switching circuit C7A are pulled out, as long as resistance R 73 can be presented the 1/h that is equal to or greater than the bias current of presenting to the control terminal T6 of switching circuit Q7A _FE(h here _FEBe the h parameter of NPN transistor Q7A) electric current get final product.Thereby, set suitable value for by the current value that will flow through resistance R 7_3A, for resistance R 7_3, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

According to a seventh embodiment of the invention another example of configuration of led drive circuit shown in Fig. 7 B.By with in the same manner configuration shown in Figure 5 is made amendment from the modification that Fig. 6 to Fig. 7 carried out, that is, replace constant-current circuit B5 by using resistance R 7_3B, thereby obtain the configuration shown in Fig. 7 B.Resistance R 7_3B presents base current to NPN transistor Q7B, and the electric current that flows through resistance R 7_3B equals the 1/h of the bias current presented to the control terminal T6 of switching circuit C7B _FE(h here _FEBe the h parameter of NPN transistor Q7B).The overtemperature protection operation that will cause NPN transistor Q7B to be in off-state is taken into account; set suitable value for by the current value that will flow through resistance R 7_3B; for resistance R 7_3B, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

＜the eight embodiment 〉

Shown in Fig. 8 according to the configuration of the led drive circuit of the eighth embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 8 is provided with: bridge diode 2; Constant-current circuit A8 and B8; Resistance R 8; NPN transistor Q8; And positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP8.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A8 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A8 is connected to another output of bridge diode 2.And an end of resistance R 8 is connected to the negative electrode of led module 3, and the other end of resistance R 8 is connected to the collector electrode of bias current terminal T3 and the NPN transistor Q8 of constant-current circuit A8.The emitter of NPN transistor Q8 is connected to another output of bridge diode 2.And constant-current circuit B8 is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q8, and PTC resistance R P8 is arranged between the base stage and emitter of NPN transistor Q8.

To PTC resistance R P8 circulation electric current is arranged from constant-current circuit B8, and the resistance value of the constant current value of constant-current circuit B8 and PTC resistance R P8 set for make that NPN transistor Q8 remains on off-state at normal temperatures.And, bias current is fed to the bias current terminal T3 of constant-current circuit A8 by resistance R 8 from the negative electrode of led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A8) set at constant-current circuit A8.

In the led drive circuit of present embodiment shown in Figure 8, along with ambient temperature rises, the resistance value of PTC resistance R P8 increases, and causes the base stage of NPN transistor Q8 and the voltage between the emitter to increase.Therefore, NPN transistor Q8 makes the bias current of presenting to the bias current terminal T3 of constant-current circuit A8 reduce, and consequently the constant current value of constant-current circuit A8 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 8 reaches predefined specified level or when higher, all bias currents that NPN transistor Q8 will present to the bias current terminal T3 of constant-current circuit A8 are pulled out, and consequently do not present bias current to the bias current terminal T3 of constant-current circuit A8.Therefore, constant-current circuit A8 is placed in off-state.

In the led drive circuit of present embodiment shown in Figure 8, directly limit the output of constant-current circuit A8, thereby this constant-current circuit A8 presents constant current driving LED module 3 to led module 3 by NPN transistor Q8.Though some is heavy for the load on the NPN transistor Q8, it can reduce the size of resulting circuit.

PTC resistance R P8 is being arranged under the base stage and the situation between the emitter of NPN transistor Q8, by setting its resistance value for suitable value, for PTC resistance R P8, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And; constant-current circuit B8 presents base current to NPN transistor Q8; make NPN transistor Q8 when being placed in conducting state because of the overtemperature protection operation; all bias currents that to present to the bias current terminal T3 of constant-current circuit A8 are pulled out, as long as constant-current circuit Q8 can present the 1/h that is equal to or greater than the bias current of presenting to the bias current terminal T3 of constant-current circuit A8 _FE(h here _FEBe the h parameter of NPN transistor Q8) electric current get final product.Thereby, by setting its constant current value for suitable value,, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong for constant-current circuit B8.

＜the nine embodiment 〉

Shown in Fig. 9 according to the configuration of the led drive circuit of the ninth embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 9 is provided with: bridge diode 2; Constant-current circuit A9 and B9; Resistance R 9; NPN transistor Q9; And positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP9_1 and RP9_2.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of anode led module 3.The constant current terminal T1 of constant-current circuit A9 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A9 is connected to another output of bridge diode 2.And an end of resistance R 9 is connected to the negative electrode of led module 3, and the other end of resistance R 9 is connected to the collector electrode of bias current terminal T3 and the NPN transistor Q9 of constant-current circuit A9 by PTC resistance R P9_2.The emitter of NPN transistor Q9 is connected to another output of bridge diode 2.And constant-current circuit B9 is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q9, and PTC resistance R P91 is arranged between the base stage and emitter of NPN transistor Q9.

To PTC resistance R P9_1 circulation electric current is arranged from constant-current circuit B9, and the resistance value of the constant current value of constant-current circuit B9 and PTC resistance R P9_1 set for make that NPN transistor Q9 remains on off-state at normal temperatures.And, bias current is fed to the bias current terminal T3 of constant-current circuit A9 by resistance R 9 and PTC resistance R 9_2 from the negative electrode of led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A9) set at constant-current circuit A9.

In the led drive circuit of present embodiment shown in Figure 9, along with ambient temperature rises, the resistance value of PTC resistance R P9_1 and PTC resistance R P9_2 increases, and causes the base stage of NPN transistor Q9 and the voltage between the emitter to increase.Therefore, NPN transistor Q9 makes the bias current of presenting to the bias current terminal T3 of constant-current circuit A9 reduce, and consequently the constant current value of constant-current circuit A9 is restricted.And, thereby also limit the bias current of presenting to the bias current terminal T3 of constant-current circuit A9 by the resistance value of using PTC resistance R 9_2.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 9 reaches predefined specified level or when higher, all bias currents that NPN transistor Q9 will present to the bias current terminal T3 of constant-current circuit A9 are pulled out, and consequently do not present bias current to the bias current terminal T3 of constant current A9.Therefore, constant-current circuit A9 is placed in off-state.

In the led drive circuit of present embodiment shown in Figure 9, the bias current that PTC resistance R 9_2 restriction is presented to the bias current terminal T3 of constant-current circuit A9, so and NPN transistor Q9 directly pulls out this bias current, drives this led module 3 thereby described constant-current circuit A9 presents constant current to led module 3.Thereby, more promptly limit the output of constant-current circuit A9.

PTC resistance R P9_1 is being arranged under the base stage and the situation between the emitter of NPN transistor Q9, by setting its resistance value for suitable value, for PTC resistance R P9_1, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And; constant-current circuit B9 presents base current to NPN transistor Q9; make NPN transistor Q9 when being placed in conducting state because of the overtemperature protection operation; all bias currents that to present to the bias current terminal T3 of constant-current circuit A9 are pulled out, as long as constant-current circuit B9 can present the 1/h that is equal to or greater than the bias current of presenting to the bias current terminal T3 of constant-current circuit A9 _FE(h here _FEBe the h parameter of NPN transistor Q9) electric current get final product.Thereby, by setting its constant current value for suitable value,, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong for constant-current circuit B9.

PTC resistance R P9_2 is applied in by resulting pulsating voltage after PTC resistance R P9_2 and resistance R 9 dividing potential drops.Therefore, thus PTC resistance R P9_2 need be configured to drop on the resistance value that rated power and rated voltage obtain with interior value by use.

Also can make amendment to configuration shown in Figure 8 and configuration shown in Figure 9 in the same manner with the modification of being carried out from Fig. 6 to Fig. 7 A.That is, constant-current circuit B8 and B9 can be replaced by the resistance with suitable resistance value.

The example of the configuration of＜constant-current circuit 〉

Then, thus shown in Figure 10ly present the constant-current circuit of constant current driving LED module to led module---be the example of the configuration of constant-current circuit A1 to A6, A7A, A7B, A8, A9 among above-mentioned first to the 9th embodiment.Constant-current circuit shown in Figure 10 is provided with: NPN transistor Q10; Resistance R 10; Zener diode ZD10; Constant current terminal T1 and T2; And bias current terminal T3.

The base stage of NPN transistor Q10 is connected to negative electrode and the bias current terminal T3 of Zener diode ZD10, the collector electrode of NPN transistor Q10 is connected to constant current terminal T1, and the emitter of NPN transistor Q10 is connected to anode and the constant current terminal T2 of Zener diode ZD10 by resistance R 10.

In addition, thus shown in Figure 11ly present the constant-current circuit of constant current driving LED module to led module---be constant-current circuit A1 to A6, A7A, A7B, A8, and the example of the configuration of A9 among above-mentioned first to the 9th embodiment.Constant-current circuit shown in Figure 11 is provided with: PNP transistor Q11; Resistance R 11; Zener diode ZD11; Constant current terminal T1 and T2; And bias current terminal T3.

The base stage of PNP transistor Q11 is connected to anode and the bias current terminal T3 of Zener diode ZD11, the emitter of PNP transistor Q11 is connected to negative electrode and the constant current terminal T1 of Zener diode ZD11 by resistance R 11, and the collector electrode of PNP transistor Q11 is connected to constant current terminal T2.

Two constant current value of the constant-current circuit shown in Figure 10 and 11 all are expressed as (V _Z-V _BE)/R, V here _ZThe Zener voltage of expression Zener diode ZD10 or ZD11, V _BEExpression NPN transistor Q10 or the base stage of PNP transistor Q11 and the voltage between the emitter, and R represents the resistance value of resistance R 10 or R11.

Constant-current circuit shown in Figure 10 and constant-current circuit shown in Figure 11 also can be used to after among the tenth to the 13 embodiment that describes.

Then, the constant-current circuit that makes electric current flow into negative temperature coefficient resister (hereinafter referred to as " NTC resistance ") or positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") shown in Figure 12---be above-mentioned first, second, the example of the configuration of constant-current circuit B1, B2, B5, B6, B8 and B9 among the 5th, the 6th, the 8th and the 9th embodiment.Constant-current circuit shown in Figure 12 is provided with: NPN transistor Q12_1 and Q12_2; And resistance R 12_1 and R12_2.

The base stage of NPN transistor Q12_1 is connected to the emitter of NPN transistor Q12_2 and the end of resistance R 12_2, and the collector electrode of NPN transistor Q12_1 is connected to the base stage of NPN transistor Q12_2 and the end of resistance R 12_1.The collector electrode of the other end of resistance R 12_1 and NPN transistor Q12_2 is connected to the constant current terminal on the side of constant-current circuit.The other end of the emitter of NPN transistor Q12_1 and resistance R 12_2 is connected to the constant current terminal on the opposite side of constant-current circuit.

In addition, the constant-current circuit that makes electric current flow into negative temperature coefficient resister (hereinafter referred to as " NTC resistance ") or positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") shown in Figure 13---be above-mentioned first, second, another example of the configuration of constant-current circuit B1, B2, B5, B6, B8 and B9 among the 5th, the 6th, the 8th and the 9th embodiment.Constant-current circuit shown in Figure 13 is provided with: PNP transistor Q13_1 and Q13_2; And resistance R 13_1 and R13_2.

The base stage of the transistorized Q13_1 of PNP is connected to the emitter of PNP transistor Q13_2 and the end of resistance R 13_2, and the collector electrode of the transistorized Q13_1 of PNP is connected to the base stage of PNP transistor Q13_2 and the end of resistance R 13_1.The other end of the emitter of the transistorized Q13_1 of PNP and resistance R 13_2 is connected to the constant current terminal on the side of constant-current circuit, and the collector electrode of the other end of resistance R 13_1 and PNP transistor Q13_2 is connected to the constant current terminal on the opposite side of constant-current circuit.

Two constant current value of the constant-current circuit shown in Figure 12 and 13 all are expressed as V _BE/ R, V here _BERepresent the voltage between each transistorized base stage and the emitter, and R represents the resistance value of each resistance.

As long as the arbitrary terminal among bias current terminal T3 and constant current terminal T1 or the T2 links together by the resistance with suitable value, then the constant-current circuit shown in Figure 10 or 11 can be used as the constant-current circuit that makes electric current flow into negative temperature coefficient resister or positive temperature coefficient resistor---be above-mentioned first, second, each constant-current circuit among constant-current circuit B1, B2, B5, B6, B8 and the B9 among the 5th, the 6th, the 8th and the 9th embodiment.

As long as the bias current terminal is arranged to be connected to the base stage of NPN transistor Q12_2 or PNP transistor Q13_2, thereby then Figure 12 or constant-current circuit shown in Figure 13 just can be used as constant-current circuit from constant current driving LED module to led module that present---be among above-mentioned first to the 9th embodiment constant-current circuit A1 to A6, A7A, A7B, A8, reach each constant-current circuit among the A9.And, these constant-current circuits also can be used to after among the tenth to the 13 embodiment that describes.

The example of the configuration of＜switching circuit 〉

Then, switching circuit shown in Figure 14---be the example of the configuration of switching circuit C5, C6, C7A and C7B among above-mentioned the 5th to the 7th embodiment.Switching circuit shown in Figure 14 is provided with: thyristor TTY14; Resistance R 14; Contact terminal T4 and T5; And control terminal T6.The gate pole of thyristor TTY14 is connected to an end of control terminal T6 and resistance R 14, and the anode of thyristor TTY14 is connected to contact terminal T4, and the other end of the negative electrode of thyristor TTY14 and resistance R 14 is connected to contact terminal T5.

Switching circuit shown in Figure 15---be another example of the configuration of switching circuit C5, C6, C7A and C7B among above-mentioned the 5th to the 7th embodiment.Switching circuit shown in Figure 15 is provided with: bidirectional triode thyristor TRI15; Resistance R 15; Contact terminal T4 and T5; And control terminal T6.The gate pole of bidirectional triode thyristor TRI15 is connected to an end of control terminal T6 and resistance R 15, and the anode of bidirectional triode thyristor TRI15 is connected to contact terminal T4, and the other end of the negative electrode of TRI15 and resistance R 15 is connected to contact terminal T5.

＜the ten embodiment 〉

Then, the configuration of the led drive circuit according to the tenth embodiment of the present invention shown in Figure 16.The led drive circuit of present embodiment shown in Figure 16 is provided with: bridge diode 2; Constant-current circuit A16; Switching circuit C16; Resistance R 16_1 to R16_3; And positive temperature coefficient (hereinafter referred to as " PTC resistance ") RP16.Notice that switching circuit C16 is configured to Figure 14 or shown in Figure 15.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A16 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A16 is connected to the contact terminal T4 of switching circuit C16.The contact terminal T5 of switching circuit C16 is connected to another output of bridge diode 2.And the end of resistance R 16_1 is connected to the negative electrode of led module 3, and the other end of resistance R 16_1 is connected to the bias current terminal T3 of constant-current circuit A16 and the end of resistance R 16_2.The other end of resistance R 16_2 is connected to the control terminal T6 of switching circuit C16 and the end of resistance R 16_3 by PTC resistance R P16.The other end of resistance R 16_3 is connected to another output of bridge diode 2.

Bias current is fed to the control terminal T6 of switching circuit C16 by resistance R 16_1 and R16_2 and PTC resistance R P16 from the negative electrode of led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A16) set at constant-current circuit A16.

In the led drive circuit of present embodiment shown in Figure 16, along with ambient temperature rises, the resistance value of PTC resistance R P16 increases, so the delay of the phase angle of thyristor among the switching circuit C16 or bidirectional triode thyristor, and consequently the constant current value of constant-current circuit A16 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 16 reaches predefined specified level or when higher, the gate current deficiency of thyristor among the switching circuit C16 or bidirectional triode thyristor, therefore, switching circuit C16 is placed in off-state, and constant-current circuit A16 is placed in off-state.

＜the ten one embodiment 〉

Shown in Figure 17 according to the configuration of the led drive circuit of the 11st embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 17 is provided with: bridge diode 2; Constant-current circuit A17; Switching circuit C17; Resistance R 17_1 to R17_3; Positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP17; And capacitor C AP17.Note switching circuit C17 be configured to shown in Figure 14 or 15 like that.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A17 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A17 is connected to the contact terminal T4 of switching circuit C17.The contact terminal T5 of switching circuit C17 is connected to another output of bridge diode 2.And an end of resistance R 171 is connected to the negative electrode of led module 3, and the other end of resistance R 17_1 is connected to the bias current terminal T3 of constant-current circuit A17 and the end of resistance R 17_2.The other end of resistance R 17_2 is connected to the end of control terminal T6, resistance R 17_3 of switching circuit C17 and the end of capacitor C AP17 by PTC resistance R P17.The other end of the other end of resistance R 17_3 and capacitor C AP17 is connected to another output of bridge diode 2.

Bias current is fed to the control terminal T6 of switching circuit C17 by resistance R 17_1 and R17_2 and PTC resistance R P17 from the negative electrode of led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A17) set at constant-current circuit A17.

In the led drive circuit of present embodiment shown in Figure 17, along with ambient temperature rises, the resistance value of PTC resistance R P17 increases, therefore the thyristor among the switching circuit C17 or the phase angle of bidirectional triode thyristor postpone according to the resistance value of PTC resistance R P17 and the capacitance of capacitor C AP17, and consequently the constant current value of constant-current circuit A17 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 17 reaches predefined specified level or when higher, the phase place Rotate 180 of thyristor among the switching circuit C17 or bidirectional triode thyristor °, therefore, switching circuit C17 is placed in off-state, and constant-current circuit A17 is placed in off-state.

＜the ten two embodiment 〉

Shown in Figure 18 according to the configuration of the led drive circuit of the 12nd embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 180 is provided with: bridge diode 2; Constant-current circuit A18; Switching circuit C18; Resistance R 18_1 to R18_3; And positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP18.Note switching circuit C18 be configured to shown in Figure 14 or 15 like that.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A18 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A18 is connected to the contact terminal T4 of switching circuit C18.The contact terminal T5 of switching circuit C18 is connected to another output of bridge diode 2.And the end of resistance R 18_1 is connected to the negative electrode of led module 3, and the other end of resistance R 18_1 is connected to the bias current terminal T3 of constant-current circuit A18 and the end of resistance R 18_2.The other end of resistance R 18_2 is connected to the end of PTC resistance R P18 and the end of resistance R P18_3.The other end of PTC resistance R P18 is connected to the control terminal T6 of switching circuit C18.The other end of resistance R 18_3 is connected to another output of bridge diode 2.

Bias current is fed to the control terminal T6 of switching circuit C18 by resistance R 18_1 and R18_2 and PTC resistance R P18 from the negative electrode of led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A18) set at constant-current circuit A18.

In the led drive circuit of present embodiment shown in Figure 180, along with ambient temperature rises, the resistance value of PTC resistance R P18 increases, so the phase delay of thyristor among the switching circuit C18 or bidirectional triode thyristor, and consequently the constant current value of constant-current circuit A18 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 180 reaches predefined specified level or when higher, the gate current deficiency of thyristor among the switching circuit C18 or bidirectional triode thyristor, therefore, switching circuit C18 is placed in off-state, and constant-current circuit A18 is placed in off-state.

＜the ten three embodiment 〉

Shown in Figure 19 according to the configuration of the led drive circuit of the 13rd embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 19 is provided with: bridge diode 2; Constant-current circuit A19; Switching circuit C19; Resistance R 19_1 to R19_3; Positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP19_1 and RP19_2.Note switching circuit C19 be configured to shown in Figure 14 or 15 like that.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A19 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A19 is connected to the contact terminal T4 of switching circuit C19.The contact terminal T5 of switching circuit C19 is connected to another output of bridge diode 2.And the end of resistance R 19_1 is connected to the negative electrode of led module 3, and the other end of resistance R 19_1 is connected to the bias current terminal T3 of constant-current circuit A19 and the end of resistance R 19_2.The other end of resistance R 19_2 is connected to the end of PTC resistance R P19_2 and the end of resistance R 19_3 by PTC resistance R P19_1.The other end of PTC resistance R P19_2 is connected to the control terminal T6 of switching circuit C19.The other end of resistance R 19_3 is connected to another output of bridge diode 2.

Can be with bias current from the negative electrode of led module 3 by resistance R 19_1 and R19_2 and then be fed to the control terminal T6 of switching circuit C19 by PTC resistance R P19_1 and RP19_2.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value; Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A19) set at constant-current circuit A19.

In the led drive circuit of present embodiment shown in Figure 19, along with ambient temperature rises, the resistance value of PTC resistance R P19_1 and RP19_2 increases, therefore the phase angle of thyristor among the switching circuit C19 or bidirectional triode thyristor postpones, and consequently the constant current value of constant-current circuit A19 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 19 reaches predefined specified level or when higher, the gate current deficiency of thyristor among the switching circuit C19 or bidirectional triode thyristor, therefore, switching circuit C19 is placed in off-state, and constant-current circuit A19 is placed in off-state.

＜the ten four embodiment 〉

The configuration of the led drive circuit shown in Figure 21 in the 14th embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 21 is provided with: bridge diode 2; Constant-current circuit A21, B21_1 and B21_2; NPN transistor Q21_1 and Q21_2; Resistance R 21; And positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP21.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A21 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A21 is connected to another output of bridge diode 2.The collector electrode of NPN transistor Q21_1 is connected to the negative electrode of led module 3, and the emitter of NPN transistor Q21_1 is connected to the bias current terminal T3 of constant-current circuit A21 by resistance R 21.And constant-current circuit B21_1 is connected between the negative electrode of the base stage of NPN transistor Q21_1 and led module 3.The collector electrode of NPN transistor Q21_2 is connected to the base stage of NPN transistor Q21_1, and the emitter of NPN transistor Q21_2 is identical with constant-current circuit T2, is connected to another output of bridge diode 2.And constant-current circuit B21_2 is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q21_2, and PTC resistance R P21 is arranged between the base stage and emitter of NPN transistor Q21_2.

NPN transistor Q21_1 is controlled by constant-current circuit B21_1 and NPN transistor Q21_2, thereby presents bias current to the bias current terminal T3 of constant-current circuit A21.In the led drive circuit of present embodiment shown in Figure 21, thereby the bias current that the base current restriction of NPN transistor Q21_2 control NPN transistor Q21_1 is presented to the bias current terminal T3 of constant-current circuit A21, so that the output of restriction constant-current circuit A21, thereby this constant-current circuit A21 presents constant current driving LED module 3 to led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and be applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A21) set at constant-current circuit A21.

In the led drive circuit of present embodiment shown in Figure 21, along with ambient temperature rises, then the resistance value of PTC resistance R P21 increases, and causes the base stage of NPN transistor Q21_2 and the voltage between the emitter to increase.Thereby the base current of NPN transistor Q21_1 reduces, and the bias current of presenting to bias current terminal T3 reduces, and therefore, the constant current of constant-current circuit A21 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 21 reaches predefined specified level or when higher, NPN transistor Q21_1 is placed in off-state, does not consequently present bias current to the bias current terminal T3 of constant-current circuit A21.Therefore, constant-current circuit A21 is placed in off-state.

PTC resistance R P21 is being arranged under the base stage and the situation between the emitter of NPN transistor Q21_2, by setting its resistance value for suitable value, for PTC resistance R P21, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

＜the ten five embodiment 〉

Shown in Figure 22 according to the configuration of the led drive circuit of the 15th embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 22 is provided with: bridge diode 2; Constant-current circuit A22 and B22; NPN transistor Q22_1 and Q22_2; Resistance R 22_1 and R22_2; And positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP22.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A22 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A22 is connected to another output of bridge diode 2.The collector electrode of NPN transistor Q22_1 is connected to the negative electrode of led module 3, and the emitter of NPN transistor Q22_1 is connected to the bias current terminal T3 of constant-current circuit A22 by resistance R 22_1.And resistance R 22_2 is connected between the negative electrode of the base stage of NPN transistor Q22_1 and led module 3.The collector electrode of NPN transistor Q22_2 is connected to the base stage of NPN transistor Q22_1, and the emitter of NPN transistor Q22_2 is identical with constant current terminal T2, is connected to another output of bridge diode 2.And constant-current circuit B22 is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q22_2, and PTC resistance R P22 is arranged between the base stage and emitter of NPN transistor Q22_2.

NPN transistor Q22_1 is controlled by resistance R 22_2 and NPN transistor Q22_2, thereby presents bias current to the bias current terminal T3 of constant-current circuit A22.In the led drive circuit of present embodiment shown in Figure 22, thereby the bias current that the base current restriction of NPN transistor Q22_2 control NPN transistor Q22_1 is presented to the bias current terminal T3 of constant-current circuit A22, so that the output of restriction constant-current circuit A22, thereby this constant-current circuit A22 presents constant current driving LED module 3 to led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A22) set at constant-current circuit A22.

In the led drive circuit of present embodiment shown in Figure 22, along with ambient temperature rises, the resistance value of PTC resistance R P22 increases, and causes the base stage of NPN transistor Q22_2 and the voltage between the emitter to increase.Thereby the base current of NPN transistor Q22_1 reduces, and therefore the bias current of presenting to bias current terminal T3 reduces, and consequently the constant current value of constant-current circuit A22 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 22 reaches predefined specified level or when higher, NPN transistor Q22_1 is placed in off-state, does not consequently present bias current to the bias current terminal T3 of constant-current circuit A22.Therefore, constant-current circuit A22 is placed in off-state.

PTC resistance R P22 is being arranged under the base stage and the situation between the emitter of NPN transistor Q22_2, by setting its resistance value for suitable value, for PTC resistance R P22, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

＜the ten six embodiment 〉

Shown in Figure 23 according to the configuration of the led drive circuit of the 16th embodiment of the present invention.The led drive circuit of present embodiment shown in Figure 23 is provided with: bridge diode 2; Constant-current circuit A23; NPN transistor Q23_1 and Q23_2; Resistance R 23_1 to R23_3; And positive temperature coefficient resistor (hereinafter referred to as " PTC resistance ") RP23.

The input of bridge diode 2 is connected to commercial AC 100V power supply 1, and an output of bridge diode 2 is connected to the anode of led module 3.The constant current terminal T1 of constant-current circuit A23 is connected to the negative electrode of led module 3, and the constant current terminal T2 of constant-current circuit A23 is connected to another output of bridge diode 2.The collector electrode of NPN transistor Q23_1 is connected to the negative electrode of led module 3, and the emitter of NPN transistor 23_1 is connected to the bias current terminal T3 of constant-current circuit A23 by resistance R 23_1.And resistance R 23_2 is connected between the negative electrode of the base stage of NPN transistor Q23_1 and led module 3.The collector electrode of NPN transistor Q23_2 is connected to the base stage of NPN transistor Q23_1, and the emitter of NPN transistor R23_2 is identical with constant current terminal T2, is connected to another output of bridge diode 2.And resistance 23_3 is arranged between the base stage of the negative electrode of led module 3 and NPN transistor Q23_2, and PTC resistance R P23 is arranged between the base stage and emitter of NPN transistor Q23_2.

NPN transistor Q23_1 is controlled by resistance R 23_2 and NPN transistor Q23_2, thereby presents bias current to the bias current terminal T3 of constant-current circuit A23.In the led drive circuit of present embodiment shown in Figure 23, thereby the bias current that the base current restriction of NPN transistor Q23_2 control NPN transistor Q23_1 is presented to the bias current terminal T3 of constant-current circuit A23, so that the output of restriction constant-current circuit A23, thereby this constant-current circuit A23 presents constant current driving LED module 3 to led module 3.

Carry out full-wave rectification from the AC voltage of commercial AC100V power supply 1 output by bridge diode 2, be about the pulsating voltage of 141V and it is applied to led module 3 thereby obtain its peak value.Therefore, the electric current that flows through led module 3 also becomes pulsation, and its peak value equals the value (constant current value of constant-current circuit A23) set at constant-current circuit A23.

In the led drive circuit of present embodiment shown in Figure 23, along with ambient temperature rises, the resistance value of PTC resistance R P23 increases, and causes the base stage of NPN transistor Q23_2 and the voltage between the emitter to increase.Thereby the base current of NPN transistor Q23_1 reduces, and the bias current of presenting to bias current terminal T3 reduces, and therefore, the constant current value of constant-current circuit A23 is restricted.When the ambient temperature of the led drive circuit of present embodiment shown in Figure 23 reaches predefined specified level or when higher, NPN transistor Q23_1 is placed in off-state, does not consequently present bias current to the bias current terminal T3 of constant-current circuit A23.Therefore, constant-current circuit A23 is placed in off-state.

PTC resistance R P23 is being arranged under the base stage and the situation between the emitter of NPN transistor Q23_2, by setting its resistance value for suitable value, for PTC resistance R P23, can use the lower device of its rated power or its withstand voltage not high device, and can not go wrong.

And resistance R 23_3 presents base current to NPN transistor Q23_2, and the electric current that flows through resistance 23_2 is used to control NPN transistor Q23_1, and this NPN transistor Q23_1 presents bias current to the bias current terminal T3 of constant-current circuit A23.As long as set the resistance value of resistance R 23_3 for suitable value; even do not reach temperature at the overtemperature protection operating and setting; when led module 3 grades become unusually (short circuit or near short circuit) cause applying under the voltage condition beyond the regular event scope to constant-current circuit A23; the base stage of NPN transistor Q23_2 and the voltage between the emitter rise; the base stage of NPN transistor Q23_1 and the voltage between the emitter reduce; the bias current of presenting to bias current terminal T3 reduces, so the constant current value of constant-current circuit A23 is restricted.Thereby, the overheating protection circuit that resistance R 23_3 can be limited with the constant current value of doing constant-current circuit A23.

＜other 〉

In switching circuit shown in Figure 14, thyristor TTY14 can replace with photosensitive thyristor, and in switching circuit shown in Figure 15, bidirectional triode thyristor TRI15 can replace with photosensitive bidirectional triode thyristor.For this reason, the cathode leg on the input side needs ground connection.

The commercial in Japan 100V voltage that provides is provided the input voltage of led drive circuit of the present invention.By setting the circuit constant of led drive circuit of the present invention for suitable value, thus can be with other country at the commercial voltage that provides or the alternating voltage after the step-down input voltage as led drive circuit of the present invention.

And, by led drive circuit of the present invention being added protection device, can provide safer LED drive unit such as current fuse.

And, in each figure of the Fig. 1 to 19 Figure 10 to Figure 15 and Figure 21 to 23, not only can be connected to the negative electrode of led module with present the constant-current circuit of electric current or an end of resistance to corresponding resistance with plus or minus temperature coefficient, thus but also can be by setting current value or resistance value for anode that suitable value is connected to led module.

For example, in the situation of Fig. 1, the end of NTC resistance R N1 is connected to the negative electrode of led module 3, and in the situation of Fig. 5, the end of constant-current circuit B5 is connected to the negative electrode of led module 3.Each end also can be connected to the anode of led module 3.

Thus, guaranteed before constant-current circuit A1 to A19 starts, make constant-current circuit A1 to A19 and switching circuit C5 to C19 conducting and disconnection reliably or limit it.

And; by from the switching circuit shown in the constant-current circuit shown in Figure 10 to 13 and Figure 14 and 15, suitably selecting constant-current circuit and switching circuit respectively; and they are suitably connected, thereby the led drive circuit that is equipped with overheat protective function can be connected between the anode of bridge diode and led module.

Overtemperature protection portion is the part that is formed by thermistor etc., and the resistance value of this thermistor has bigger variation with temperature, and when superheating phenomenon takes place when the restriction electric current.Thermistors etc. are arranged near heating region or its, and it is overheated to detect.And that light adjusting circuit is set is identical with the incandescent lamp of control light etc. with some back level at the AV power supply, light adjusting circuit also can be set with control light in a circuit according to the invention.

Claims (29)

1. led drive circuit, this led drive circuit driving LED is characterized in that, comprising:

Rectification circuit, described rectification circuit converts alternating voltage to pulsating voltage;

Constant-current circuit; And

Overtemperature protection portion, described overtemperature protection portion limits the output of described constant-current circuit,

Wherein said LED and described constant-current circuit are connected in series on the outlet side of described rectification circuit.

2. led drive circuit as claimed in claim 1 is characterized in that,

Described overtemperature protection portion comprises:

The PNP transistor; And

Resistance, described resistance has negative temperature coefficient, and is arranged between transistorized base stage of described PNP and the emitter.

3. led drive circuit as claimed in claim 2 is characterized in that,

The transistorized described emitter and collector of described PNP is connected to the path of circulate among from the constant current of described constant-current circuit output.

4. led drive circuit as claimed in claim 2 is characterized in that,

Described overtemperature protection portion also comprises:

Constant-current source, described constant-current source is connected in series with the described resistance with described negative temperature coefficient,

Magnitude of voltage between transistorized described base stage of wherein said PNP and the described emitter is the product that multiplies each other and obtain by with the constant current value of described constant-current source and the resistance value with described resistance of described negative temperature coefficient.

5. led drive circuit as claimed in claim 2 is characterized in that,

Described overtemperature protection portion also comprises:

Resistive element, described resistive element is connected in series with the described resistance with described negative temperature coefficient,

Magnitude of voltage between transistorized described base stage of wherein said PNP and the emitter is the product that current value and the resistance value with described resistance of described negative temperature coefficient by the electric current that will flow through described resistance with described negative temperature coefficient and described resistive element multiplies each other and obtain.

6. led drive circuit as claimed in claim 1 is characterized in that,

Described overtemperature protection portion comprises:

NPN transistor; And

Resistance, described resistance has negative temperature coefficient, and is arranged between the base stage and emitter of described NPN transistor,

The described emitter and collector of described NPN transistor is connected to the path of circulate among from the constant current of described constant-current circuit output.

7. led drive circuit as claimed in claim 1 is characterized in that, also comprises:

Switching circuit, described switching circuit switch the conducting and the disconnection of described constant-current circuit,

Wherein said LED, described constant-current circuit and described switching circuit are connected in series on the outlet side of described rectification circuit, and

Described overtemperature protection portion controls described switching circuit.

8. led drive circuit as claimed in claim 7 is characterized in that,

Described overtemperature protection portion comprises:

Bipolar transistor, described bipolar transistor is presented bias current to the control terminal of described switching circuit; And

Resistance, described resistance has negative temperature coefficient, and the one end is connected to the base stage of described bipolar transistor,

The described base stage of wherein said bipolar transistor and the voltage between the emitter change according to the resistance value with described resistance of described negative temperature coefficient.

9. led drive circuit as claimed in claim 7 is characterized in that,

Described overtemperature protection portion comprises:

NPN transistor, described NPN transistor will be pulled out to the bias current that the control terminal of described switching circuit is presented; And

Resistance, described resistance has positive temperature coefficient, and the one end is connected to the base stage of described NPN transistor,

The described base stage of wherein said NPN transistor and the voltage between the emitter change according to the resistance value with described resistance of described positive temperature coefficient.

10. led drive circuit as claimed in claim 8 is characterized in that,

Described overtemperature protection portion also comprises:

Constant-current source, described constant-current source is connected in series with the described resistance with described negative temperature coefficient,

The described base stage of wherein said bipolar transistor and the magnitude of voltage between the emitter are the products that multiplies each other and obtain by with the constant current value of described constant-current source and the resistance value with described resistance of described negative temperature coefficient.

11. led drive circuit as claimed in claim 9 is characterized in that,

Described overtemperature protection portion also comprises:

Constant-current source, described constant-current source is connected in series with the described resistance with described positive temperature coefficient,

The described base stage of wherein said NPN transistor and the magnitude of voltage between the emitter are the products that multiplies each other and obtain by with the constant current value of described constant-current source and the resistance value with described resistance of described positive temperature coefficient.

12. led drive circuit as claimed in claim 8 is characterized in that,

Described overtemperature protection portion also comprises:

Resistive element, described resistive element is connected in series with the described resistance with described negative temperature coefficient,

The described base stage of wherein said bipolar transistor and the magnitude of voltage between the emitter are the products that value and the resistance value with described resistance of described negative temperature coefficient by the electric current that will flow through described resistance with described negative temperature coefficient and described resistive element multiplies each other and obtain.

13. led drive circuit as claimed in claim 9 is characterized in that,

Described overtemperature protection portion also comprises:

Resistive element, described resistive element is connected in series with the described resistance with described positive temperature coefficient,

The described base stage of wherein said NPN transistor and the magnitude of voltage between the emitter are the products that value and the resistance value with described resistance of described positive temperature coefficient by the electric current that will flow through described resistance with described positive temperature coefficient and described resistive element multiplies each other and obtain.

14. led drive circuit as claimed in claim 1 is characterized in that,

Described overtemperature protection portion comprises:

NPN transistor, described NPN transistor will be pulled out to the bias current that described constant-current circuit is presented; And

Resistance, described resistance has positive temperature coefficient, and is arranged between the base stage and emitter of described NPN transistor.

15. led drive circuit as claimed in claim 14 is characterized in that,

Described overtemperature protection portion comprises:

Constant-current source, described constant-current source is connected in series with the described resistance with described positive temperature coefficient,

The described base stage of wherein said NPN transistor and the magnitude of voltage between the emitter are the products that multiplies each other and obtain by with the constant current value of described constant-current source and the resistance value with described resistance of described positive temperature coefficient.

16. led drive circuit as claimed in claim 14 is characterized in that,

Described overtemperature protection portion also comprises:

Resistive element, described resistive element is connected in series with the described resistance with described positive temperature coefficient,

The described base stage of wherein said NPN transistor and the magnitude of voltage between the emitter are the products that value and the resistance value with described resistance of described positive temperature coefficient by the electric current that will flow through described resistance with described positive temperature coefficient and described resistive element multiplies each other and obtain.

17. led drive circuit as claimed in claim 14 is characterized in that,

Described overtemperature protection portion also comprises:

Another resistance, described another resistance has positive temperature coefficient, and is arranged with the described resistance branch with described positive temperature coefficient,

Described another resistance that wherein has described positive temperature coefficient is set to described constant-current circuit to be presented on the path of described bias current.

18. led drive circuit as claimed in claim 1 is characterized in that,

Described overtemperature protection portion comprises:

Npn bipolar transistor, described npn bipolar transistor is presented bias current to the bias current terminal of described constant-current circuit;

Control is with the npn bipolar transistor and first constant-current source, and described control is connected to the base stage of described npn bipolar transistor respectively with the npn bipolar transistor and first constant-current source, and is used to control described bias current;

Resistance, described resistance has positive temperature coefficient, and the one end is connected to the base stage of described control with npn bipolar transistor; And

Second constant-current source, described second constant-current source is connected in series with the described resistance with described positive temperature coefficient,

Wherein said control is the product that multiplies each other and obtain by with the constant current value of described second constant-current source and the resistance value with described resistance of described positive temperature coefficient with the described base stage of NPN transistor and the magnitude of voltage between the emitter.

19. led drive circuit as claimed in claim 1 is characterized in that,

Described overtemperature protection portion comprises:

Npn bipolar transistor, described npn bipolar transistor is presented bias current to the bias current terminal of described constant-current circuit;

Control is connected to the base stage of described npn bipolar transistor with npn bipolar transistor and resistive element, described control respectively with npn bipolar transistor and resistive element, and is used to control described bias current;

Resistance, described resistance has positive temperature coefficient, and the one end is connected to the base stage of described control with NPN transistor; And

Constant-current source, described constant-current source is connected in series with the described resistance with described positive temperature coefficient,

Wherein said control is the product that multiplies each other and obtain by with the constant current value of described constant-current source and the resistance value with described resistance of described positive temperature coefficient with the described base stage of npn bipolar transistor and the magnitude of voltage between the emitter.

20. led drive circuit as claimed in claim 1 is characterized in that,

Described overtemperature protection portion comprises:

Npn bipolar transistor, described npn bipolar transistor is presented bias current to the bias current terminal of described constant-current circuit;

Control is with the npn bipolar transistor and first resistive element, and described control is connected to the base stage of described npn bipolar transistor respectively with the npn bipolar transistor and first resistive element, and is used to control described bias current;

Resistance, described resistance has positive temperature coefficient, and the one end is connected to the base stage of described control with NPN transistor; And

Second resistive element, described second resistive element is connected in series with the described resistance with described positive temperature coefficient,

Wherein said control is the product that value and the resistance value with described resistance of described positive temperature coefficient of the electric current by will flowing through described resistance with described positive temperature coefficient and described second resistive element multiplies each other and obtain with the described base stage of NPN transistor and the magnitude of voltage between the emitter.

21. led drive circuit as claimed in claim 1 is characterized in that,

Described constant-current circuit comprises:

First resistance;

Zener diode; And

First bipolar transistor, the emitter of described first bipolar transistor are connected to an end of described first resistance, and the base stage of described first bipolar transistor is connected to an end of described Zener diode.

22. led drive circuit as claimed in claim 1 is characterized in that,

Described constant-current circuit comprises:

First bipolar transistor;

Second bipolar transistor;

First resistance, an end of described first resistance is connected to the base stage of described second bipolar transistor; And

Second resistance, described second resistance are arranged between the base stage and emitter of described first bipolar transistor,

The described base stage of the collector electrode of wherein said first bipolar transistor and described second bipolar transistor links together, and the emitter of the described base stage of described first bipolar transistor and described second bipolar transistor links together.

23. led drive circuit as claimed in claim 7 is characterized in that,

Described switching circuit comprises:

Thyristor or bidirectional triode thyristor; And

First resistance, described first resistance is arranged between the gate pole and negative electrode of described thyristor or described bidirectional triode thyristor.

24. led drive circuit as claimed in claim 7 is characterized in that,

Described switching circuit comprises:

Thyristor or bidirectional triode thyristor; And

First resistance, described first resistance are arranged between the gate pole and negative electrode of described thyristor or described bidirectional triode thyristor,

And

Described overtemperature protection portion comprises:

Resistance, described resistance has positive temperature coefficient, and is arranged on to the described gate pole of described thyristor or described bidirectional triode thyristor and presents on the path of bias current; And

Resistive element, described resistive element are arranged between the cathode output end of the described gate pole of described thyristor or described bidirectional triode thyristor and described rectification circuit.

25. led drive circuit as claimed in claim 24 is characterized in that,

Described overtemperature protection portion comprises:

Electric capacity, described electric capacity and described resistive element are connected in parallel.

26. led drive circuit as claimed in claim 7 is characterized in that,

Described switching circuit comprises:

Thyristor or bidirectional triode thyristor; And

First resistance, described first resistance has positive temperature coefficient, and is arranged between the gate pole and negative electrode of described thyristor or described bidirectional triode thyristor,

And

Described overtemperature protection portion comprises:

Resistance, described resistance has positive temperature coefficient, and the one end is connected to the described gate pole of described thyristor or described bidirectional triode thyristor; And

Resistive element, described resistive element are arranged between the cathode output end of the other end of the described resistance with described positive temperature coefficient and described rectification circuit.

27. led drive circuit as claimed in claim 26 is characterized in that,

Described overtemperature protection portion also comprises:

Another resistance, described another resistance has positive temperature coefficient, and is arranged with the described resistance branch with described positive temperature coefficient,

Described another resistance that wherein has positive temperature coefficient is arranged on to the described gate pole of described thyristor or described bidirectional triode thyristor to be presented on the path of bias current.

28. led drive circuit as claimed in claim 1 is characterized in that,

When described constant-current circuit reaches predetermined temperature or when higher, described overtemperature protection portion limits the described output of described constant-current circuit.

29. led drive circuit as claimed in claim 1 is characterized in that,

When described led module reaches predetermined temperature or when higher, described overtemperature protection portion limits the described output of described constant-current circuit.

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