KR101042090B1 - Alternative current light emitting diode circuit having constant current protecting circuit - Google Patents

Abstract

The present invention relates to an AC light emitting diode circuit having a constant current circuit, and more particularly, to an AC light emitting diode circuit having a constant current circuit such that illuminance and output are constant even when alternating current is used as a power source for driving the light emitting diode. . Such an AC light emitting diode circuit having a constant current circuit of the present invention is an AC light emitting diode circuit having an AC light emitting diode portion composed of a plurality of AC light emitting diodes driven by an AC power source (AC). A constant current unit controlling the current of the AC power source AC to be constantly output; A first diode having an anode connected to the AC light emitting diode unit and a cathode connected to an input terminal of the constant current unit; A second diode having an anode connected to the AC power source and a cathode connected to an input terminal of the constant current unit; And a third diode having a cathode connected to the AC light emitting diode unit and an anode connected to an output terminal of the constant current unit. A fourth diode having a cathode connected to the AC power source and an anode connected to an output terminal of the constant current unit; It is configured to include.

AC light emitting diode, constant current circuit

Description

Alternative current light emitting diode circuit having constant current protecting circuit

The present invention relates to an alternating light emitting diode circuit having a constant current circuit, and more particularly to an alternating light emitting diode circuit having a constant current circuit such that illuminance and output are constant even when alternating current is used as a power source for driving a light emitting diode. .

Light emitting diodes are being developed to have high brightness and high power, and are being used for lighting purposes. Light emitting diodes are generally driven at a relatively low direct current (DC) in structure, but methods such as connecting a plurality of light emitting diodes in a forward and reverse direction in order to directly drive a high voltage alternating current (AC) It is being developed and used.

In general, home and industrial lighting devices are used by connecting directly to the alternating current. In the case of a direct current driving LED, a method of adjusting the output pulse width in the rectifier may be used.

On the other hand, in the case of an incandescent lamp that emits light by heating the filament can be directly connected to the alternating current, the brightness can be adjusted by using a triac (Triac) element. Triacs are bidirectional power devices that can control bidirectional current communication with gate voltage.

Since the light emitting diode of the AC drive is also directly connected to the AC, the current changes when there is a difference in the input voltage according to the AC characteristic, so that the output of the AC light emitting diode is not constant. In addition, even when the temperature of the light emitting diode rises, the light output of the light emitting diode changes.

Hereinafter, an AC light emitting diode circuit according to the prior art will be described with reference to the accompanying drawings.

1 is a circuit diagram of an AC light emitting diode according to the prior art.

As shown in FIG. 1, the AC light emitting diode circuit according to the related art includes an AC light emitting diode circuit 1 connected to both terminals of an AC power source AC, and first to third resistors R1, R2, and R3. ) And overcurrent protection element (RT).

Here, the AC light emitting diode circuit 1 includes two or more first AC light emitting diodes D1 such that the anode and the cathode are connected to the AC power AC opposite to each other as the AC power periodically changes in magnitude and direction with time. And a second AC light emitting diode D2. The first AC light emitting diodes D1 and the second AC light emitting diodes D2 may be configured in plural in an array form.

Meanwhile, an anode of the first AC light emitting diode D1 and a first resistor R1 are connected to one side of the AC power supply, and an overcurrent protection element RT is connected to the cathode of the second AC light emitting diode D2 and one side of the AC power supply. Are connected in parallel. A second resistor R2 is connected to the cathode of the first AC light emitting diode D1 and the other side of the AC power supply, and a third resistor R3 is connected to the anode of the second AC light emitting diode D2 and the other side of the AC power source. It is connected in parallel.

However, such a conventional technology has the following problems.

First, when there is a difference in the input voltage according to the AC characteristics, the current is changed, accordingly there was a problem that the output of the AC light emitting diode is not constant.

Second, when the AC light emitting diode is continuously turned on, the temperature of the light emitting diode is increased, and thus a problem of gradually becoming brighter as the light gets hot and gradually gets hot. This phenomenon becomes more severe as the current changes, which causes a problem of inconvenience to the user and lowering the reliability of the product.

The present invention has been made in order to solve such a conventional problem, the present invention is to provide a constant current by using a constant current circuit even when AC is used as a power source for driving the light emitting diode by controlling the current of the AC power supply to a constant It is an object of the present invention to provide an AC light emitting diode circuit having a constant current circuit such that the illuminance and output of the light emitting diode circuit are constant.

The present invention for achieving the above object is, in the AC light emitting diode circuit having an AC light emitting diode unit composed of a plurality of AC light emitting diodes driven by an AC power source (AC), the AC power source applied to the AC light emitting diode unit ( A constant current unit controlling the current of AC) to be constantly output; A first diode having an anode connected to the AC light emitting diode unit and a cathode connected to an input terminal of the constant current unit; A second diode having an anode connected to the AC power source and a cathode connected to an input terminal of the constant current unit; A third diode having a cathode connected to the AC light emitting diode unit and an anode connected to an output terminal of the constant current unit; And a fourth diode having a cathode connected to the AC power source AC and an anode connected to the output terminal of the constant current unit.

Here, the constant current unit is a collector connected to the cathode of each of the first diode and the second diode, the emitter is connected to one terminal of the second resistor, the base is a transistor connected to one terminal of the first resistor, the first diode and The other terminal is connected to the cathode of each of the second diodes, and one terminal is connected to the anode of the internal diode, and the other terminal is connected to the first resistor used as a bias resistor of the transistor and the anode of the zener diode, the third diode, and the fourth diode. It is preferably configured to include a second resistor and a diode inside the constant current portion, the cathode is connected to the cathode of the zener diode.

The constant current I output from the constant current unit is preferably set to ZD11 / R12 based on the voltage applied to the zener diode ZD11 and the resistance value of the second resistor R12.

In addition, the constant current output from the constant current unit is preferably output a constant current of the set value of 17mA to 20mA.

According to the present invention as described above has the following advantages.

First, even if an input value is changed due to a difference in time due to the characteristics of the AC power supplied to the AC light emitting diode, a constant current (18mA) can be supplied to the AC light emitting diode using a constant current circuit.

Second, since the AC LED is continuously turned on to maintain a constant constant current using a constant current circuit even when heat is generated from the LED, stable output can be achieved without changing the brightness (illuminance) of the AC LED. .

Third, the output of the AC light emitting diode can be made constant by supplying a rectified current to the AC light emitting diode used by directly applying alternating current to the light emitting diode. Therefore, the illuminance output from the AC light emitting diode can be kept constant, thereby providing a stable lighting effect to the user and increasing the reliability of the quality.

Fourth, according to the configuration of a constant current circuit using a diode and a zener diode used as a transistor and a load, it is easy to protect the light emitting diode even with a sudden change in the input AC voltage.

Hereinafter, a preferred embodiment of an AC light emitting diode circuit having a constant current circuit according to the present invention will be described in detail with reference to the accompanying drawings.

In addition, the terminology used in the present invention is a general term that is currently widely used as possible, but in certain cases, the term is arbitrarily selected by the applicant, and in this case, the meaning is described in detail in the description of the present invention, and a simple term is used. It is to be understood that the present invention is to be understood as a meaning of terms rather than names.

In addition, in describing the embodiments, descriptions of technical contents which are well known in the technical field to which the present invention belongs and are not directly related to the present invention will be omitted. This is to more clearly communicate without obscure the subject matter of the present invention by omitting unnecessary description.

(Configuration of Example)

FIG. 2 is a circuit diagram for explaining an AC light emitting diode circuit having a constant current circuit according to the first embodiment of the present invention.

As shown in FIG. 2, an AC light emitting diode circuit having a constant current circuit according to the present invention includes an AC light emitting diode unit 10, a first constant current unit 20, and first to fourth diodes D21 and D22 ( D23) and D24.

First, the AC light emitting diode unit 10 is a light emitting diode driven by an AC power source AC. At this time, the alternating current is periodically inverted in magnitude and direction according to time, so that the AC light emitting diode unit 10 includes two or more first AC light emitting diodes in which an anode and a cathode are connected in parallel to the AC power source AC in opposite directions. It consists of a diode D1 and a second alternating light emitting diode D2. As described above, the first AC light emitting diode D1 and the second AC light emitting diode D2 may be provided in plural in an array form. One terminal of the AC light emitting diode unit 10 is connected to one terminal of the AC power source AC, and the other terminal is connected to the anode of the first diode D21 and the cathode of the third diode D23. Meanwhile, the anode of the second diode D22 and the cathode of the fourth diode D24 are connected to the other terminal of the AC power source AC.

Meanwhile, the cathode of the first diode D21, the anode of the third diode D23, the anode of the second diode D22, and the fourth diode D24 are connected to the first constant current unit 20. At this time, the first diode D21 is half-wave rectified by the AC output from the AC light emitting diode unit 10 to be output to the first constant current unit 20, and the second diode D21 is output from the AC power source AC. AC is half-wave rectified and output to the first constant current unit 20. The current output from the first constant current unit 20 is output to the AC LED unit 10 through the third diode D23 or through the fourth diode D24.

The first constant current unit 20 controls the current of the AC power source AC applied to the AC light emitting diode unit 10 to be constant, and includes a transistor Q11, a first resistor R11, and a second resistor ( R12), the constant current part internal diode D11, and the zener diode ZD1.

Here, the transistor Q11 is a constant current transistor, and the first resistor R11 is a bias resistor, and the collector of the transistor 11 and one terminal of the first resistor R11 are the first diode D21 and the second diode. (D22) It is connected to each cathode. The other terminal of the first resistor R11 is connected to the base of the transistor Q11 to apply a bias voltage for turning on the transistor Q11. In addition, the other terminal of the first resistor R11 is connected to the anode of the internal diode D11 of the constant current unit. Meanwhile, the emitter of the transistor Q11 is connected to one terminal of the second resistor R12. The other terminal of the second resistor R12 is connected to an anode of each of the zener diode ZD11, the third diode D23, and the fourth diode D24. At this time, the cathode of the zener diode ZD11 is connected to the cathode of the internal diode D11 of the constant current unit.

In summary, the first diode D21 has an anode connected to the AC light emitting diode unit 10, and a cathode thereof is a collector of the transistor Q11 of the first constant current unit 20 and one side of the first resistor R11. It is connected to the terminal.

An anode of the second diode D22 is connected to the AC power source AC, and a cathode of the second diode D22 is connected to the collector of the transistor Q11 of the first constant current unit 20 and one terminal of the first resistor R11.

The third diode D23 has a cathode connected to the AC light emitting diode unit 10, and the anode is connected to one terminal of the second resistor R12 and the anode of the zener diode ZD11.

A cathode of the fourth diode D22 is connected to the AC power source AC, and an anode of the fourth diode D22 is connected to one terminal of the second resistor R12 and the anode of the zener diode ZD11.

Here, the characteristics of the Zener diode ZD11 and the diode D11 inside the first constant current unit 20 will be briefly described. The Zener diode ZD11 has a temperature coefficient of about +2 mV / ° C., thus increasing the temperature. The higher the voltage, the higher. On the other hand, the forward bias of a normal diode has a temperature coefficient of -2 mV / ° C. Therefore, in the present invention, it is possible to maintain a constant voltage regardless of the temperature change of the AC light emitting diode unit 10 by performing temperature compensation using the same.

(Operation of the embodiment)

Referring to the operation of the AC light emitting diode circuit having the constant current circuit according to the present invention, when the AC power source AC is applied, the AC power source AC is the cathode of the AC light emitting diode unit 10 or the second diode D22. Is applied to. In this case, when applied to the AC light emitting diode unit 10, the power output from the AC light emitting diode unit 10 is half-wave rectified through the first diode D21 and input to the first constant current unit 20. On the other hand, when applied to the cathode of the second diode (D22) is half-wave rectified through the second diode (D22) is input to the first constant current unit 20. This operation is repeated with a constant time difference.

Next, the case where the positive AC power is output from the AC power source AC to the AC light emitting diode unit 10 will be described with respect to the current flow of the AC light emitting diode circuit having the constant current circuit according to the present invention.

When the AC power is output from the AC power source AC to the AC LED unit 10, the AC power is output to the anode of the first diode D21 through the first AC LED D1.

The first diode D21 half-wave rectifies the + AC power input to the anode and outputs it to one side of the collector of the first transistor Q11 and the first resistor R11.

When the bias voltage is applied to the first resistor R11, the first transistor Q11 is turned on, and thus the half-wave rectified current is output to the emitter of the first transistor Q11, and the emitter of the first transistor is applied. The output current outputs the first direction constant current I1 through the second resistor R12 and the fourth diode D24. In this case, the first direction constant current I1 is input to the first light emitting diode D2 of the AC light emitting diode unit 10.

Next, a case where a predetermined time elapses and the AC power source second diode D22 + AC power source is output will be described.

When + AC power is output from the AC power source AC to the second diode D22, the second diode D22 half-wave rectifies the + AC power input to the anode to collect the collector and the first resistor (Q1) of the first transistor Q11. Output to one side of R11).

As the bias voltage is applied to the first resistor R11, the first transistor Q11 is turned on, and thus the half-wave rectified current is output to the emitter of the first transistor Q11, The current output to the emitter outputs the second direction constant current I2 through the second resistor R12 and the third diode D23. In this case, the second directional current D2 is input to the second AC light emitting diode D2 of the AC light emitting diode unit 10.

By such an operation, it can be seen that the constant current power is repeatedly supplied to the first AC light emitting diode D1 and the second AC light emitting diode D2 of the AC light emitting diode unit 10. At this time, the AC power generated from the AC power source AC is basically the first to fourth diodes (D21), (D22), (D23), and (D24) of the present invention, even if the size and direction of the AC power are periodically reversed according to the characteristics thereof. And it can be seen that it is repeatedly rectified and constant current according to the configuration of the first constant current unit 20 is repeatedly output in one set direction. In other words, it can be seen that the rectified and constant current, but the stable current is supplied to the AC light emitting diode unit 10 in the same way as the AC.

Here, the constant current I output from the first constant current unit 20 is determined as ZD11 / R12, which is a voltage applied to the zener diode ZD11 and a resistance value of the second resistor R12. Therefore, even when heat is generated or the temperature change occurs in the AC light emitting diode unit 10, a constant voltage can be maintained. Therefore, a constant current can be supplied to the AC light emitting diode unit 10. At this time, the base voltage Vb of the transistor Q11 is a value obtained by adding the zener diode voltage Vzd11 to the forward voltage drop Vf of the diode D11. That is, Vb = Vf + Vzd11, which is equivalent to the base-emitter voltage Vbe plus the zener diode voltage Vzd11. In this case, since the value of the forward voltage drop Vf of the diode D11 is 0.6v and the base-emitter voltage Vbe is also 0.6v, the value of ZD11 / R12 may be canceled. At this time, the constant current I supplied to the first and second AC light emitting diodes D1 and D2 is preferably configured to be a constant current set among 17 mA to 20 mA.

3 is a circuit diagram illustrating an AC light emitting diode circuit having a constant current circuit according to a second embodiment of the present invention.

The basic configuration of the AC light emitting diode circuit having the constant current circuit according to the second embodiment of the present invention is similar to that of the first embodiment of the present invention, but the configuration of the constant current circuit is different. That is, as shown in FIG. 3, it consists of the AC light emitting diode part 10, the 2nd constant current part 30, and the 1st-4th diode D21 (D22), D23 (D24).

Here, the configurations of the AC light emitting diode unit 10 and the first to fourth diodes D21, D22, D23, and D24 are the same as those of the first embodiment of the present invention, and thus detailed description thereof will be omitted.

The second constant current unit 50 performs negative feedback with two transistors and is used as a constant current source. The 21st transistor Q21, the 22nd transistor Q22, the 21st resistor R21, and the 22nd resistor R22 are used as the constant current source. It consists of. In this case, the collector of the twenty-first transistor Q21 and one terminal of the twenty-first resistor R21 are connected to the cathodes of the first diode D21 and the second diode D22, respectively. The emitter of the twenty-first transistor Q21 is connected to the base of the twenty-second transistor Q22 and one terminal of the twenty-second resistor R22. The other terminal of the twenty-first resistor R21 is connected to the emitter of the twenty-first transistor Q21 and the collector of the twenty-second transistor Q22. The other terminal of the twenty-second resistor R22 and the emitter of the twenty-second transistor Q22 are connected to an anode of the third diode D23 and the fourth diode D24.

Referring to the operation of the AC light emitting diode circuit having the constant current circuit according to the second embodiment of the present invention, when the AC power source AC is applied, the AC power source AC is the AC light emitting diode unit 10 or the second diode ( Is applied to the cathode of D22). In this case, when applied to the AC light emitting diode unit 10, the power output from the AC light emitting diode unit 10 is rectified through the first diode D21 and input to the second constant current unit 30. On the other hand, when applied to the cathode of the second diode (D22) is rectified through the second diode (D22) is input to the second constant current unit 30. This operation is repeated with a constant time difference.

Therefore, when the 21st transistor Q21 is biased by the 21st resistor R21 and turned on, a voltage is applied to the 22nd resistor R22 which is an emitter resistor. When the base-emitter voltage is applied to the base of the twenty-second transistor Q22 according to the voltage output through the twenty-second resistor R22, the twenty-second transistor Q22 is turned on. At this time, as the twenty-second transistor Q22 is turned on, the base current of the twenty-first transistor Q21 is classified so that a negative feedback which reduces the current output through the twenty-first transistor Q21 is performed so that the current flows constantly. . Here, the magnitude of the constant current to be determined may be determined by the value of the second resistor Q22, which is an emitter resistor. For example, when the emitter resistance value of the 22nd resistor R22 is Re, the base-emitter voltage of the second transistor is Vbe, and the constant current value to be obtained is I, the emitter resistance value Re = Can be obtained as Vbe / I2. Therefore, the stable current can be supplied to the AC light emitting diode unit 10.

Although the present invention has been described with various examples as described above, the present invention is not necessarily limited to these examples, and various modifications can be made without departing from the spirit of the present invention. Therefore, the examples disclosed in the present invention are not intended to limit the technical idea of the present invention but to explain the present invention, and the scope of the technical idea of the present invention is not limited by these examples. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

1 is a circuit diagram for explaining an AC light emitting diode circuit according to the prior art;

2 is a circuit diagram for explaining an AC light emitting diode circuit having a constant current circuit according to a first embodiment of the present invention;

3 is a circuit diagram illustrating an AC light emitting diode circuit having a constant current circuit according to a second embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

10. AC light emitting diode part 20: First constant current part

30: second constant current portion

D1, D2: AC light emitting diodes D21, D22, D23, D24: diode

R11, R12: first and second resistor ZD11: zener diode

Claims (4)

In an AC light emitting diode circuit having an AC light emitting diode unit 10 composed of a plurality of AC light emitting diodes driven by an AC power source AC, A constant current unit controlling the current of the AC power source AC applied to the AC light emitting diode unit 10 to be constantly output; A first diode (D21) having an anode connected to the AC light emitting diode unit 10 and a cathode connected to an input terminal of the constant current unit; A second diode D22 having an anode connected to the AC power source and a cathode connected to an input terminal of the constant current unit; A third diode D23 having a cathode connected to the AC light emitting diode unit 10 and an anode connected to an output terminal of the constant current unit; And, A fourth diode D24 having a cathode connected to the AC power source and an anode connected to an output terminal of the constant current unit; AC light emitting diode circuit having a constant current circuit comprising a. The method of claim 1, The constant current unit, The collector is connected to the cathode of each of the first diode D21 and the second diode D22, the emitter is connected to one terminal of the second resistor R12, and the base is connected to one terminal of the first resistor R11. A transistor Q11 to be connected, The first terminal is connected to the other terminal of the cathode of each of the first diode (D21) and the second diode (D22), one terminal of the anode of the internal diode (D11), and used as a bias resistor of the transistor (Q11) ( R11), The second resistor R12 having the other terminal connected to the anode of the zener diode ZD11, the third diode D23 and the fourth diode D24; And a constant current circuit internal diode (D11) having a cathode connected to the cathode of the zener diode (ZD11). The method of claim 2. The constant current I output from the constant current unit is determined by ZD11 / R12 by the voltage applied to the zener diode ZD11 and the resistance value of the second resistor R12. Light emitting diode circuit. The method of claim 1, The constant current unit, A collector is connected to the cathode of each of the first diode D21 and the second diode D22, the emitter is connected to one terminal of the twenty-second resistor R22, and the base is connected to one terminal of the twenty-first resistor R21. A twenty-first transistor Q21 to be connected; The twenty-first resistor R21 connected to the cathode of each of the first diode D21 and the second diode D22 and the collector of the twenty-second transistor Q22 and the base of the twenty-first transistor Q21; The twenty-second resistor R22 having the other terminal connected to an emitter of the twenty-second transistor Q22, the anode of the third diode D23 and the fourth diode D24, And a twenty-second transistor (Q22) having an emitter connected to the other terminal of the twenty-second resistor (R22) and an anode of the third diode (D23) and the fourth diode (D24). AC light emitting diode circuit having a.

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