JP2011113958A - Highly-efficient ac led lighting-up circuit assembling capacitive reactance element and rush current preventing circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED lighting-up circuit utilizing a commercial power source or the other AC power source and generating no high frequency noises at high efficiency. <P>SOLUTION: The highly-efficient lighting-up circuit can attain high efficiency by using a capacitive reactance element for a current limiting element of an LED. A rush current flowing time and conduction starting of an electronic switch are delayed by a delay circuit since rush current transitionally flowing at the time of starting lighting-up is circulated to a bypass circuit and the electronic switch such as a transistor is arranged on the LED in series, and the LED is protected by flowing regular current after the rush current does not flow. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an energy-saving and high-efficiency AC LED lighting circuit in the technical field related to lighting equipment and lighting equipment.

  As prior art, prior art documents relating to AC LED lighting circuits were investigated, and there are the following documents (1) to (7) that seem to be partially related.

Prior literature (1)

  As for FIG. 4, this circuit aims at high efficiency using capacitive reactance. However, after full-wave rectification with 5 rectifiers, the voltage is constant with 6 constant voltage diodes and a constant voltage is output. This voltage is supplied to 7 LEDs and 8 bleeder resistors (resistors that pass a wasteful current in order to operate the circuit stably) through 10 current limiting resistors that cause loss. Furthermore, as a power source for the automatic flashing circuit, a current must always flow through 6 constant voltage diodes. The reasons for the reduced efficiency are 8 and 10 resistors and 6 constant voltage diodes.

  In addition, the 16 capacitors connected to the base circuit of the 15 transistors darken around the 13 light receiving elements and light up after repeated blinking when entering the lighting operation. It is thought to be a thing. Regardless of the brightness of the surroundings, the inrush current generated when an AC voltage is applied to the circuit is made to flow through the constant voltage diode 6 as described above to be a constant voltage, but continues to flow even in the steady state thereafter. Obviously.

  Also in FIG. 5, full-wave rectification is performed by 25 rectifiers, stabilized by 26 constant voltage diodes, and a constant voltage is output. The inrush current generated when an AC voltage is applied in a dark state is handled by a constant voltage diode as in FIG. 4. However, inrush current also flows through 27 LEDs, so 30 in series. A current limiting resistor must be inserted. Furthermore, since 28 bleeder resistors are connected in parallel, there is a disadvantage that the loss increases.

Prior literature (2)

    With respect to FIG. 6, this circuit uses 38 capacitive reactance elements instead of LED current limiting resistors to improve efficiency. However, in order to protect 43 LEDs from inrush current, after full-wave rectification by 40 rectifiers, 41 constant voltage diodes are connected in parallel. Since the voltage of the constant voltage diode 41 needs to be higher than the terminal voltage of the 43 LED, the inrush current first flows through the 43 LED having a low terminal voltage, and the current gradually increases, so that the terminal voltage of the 43 LED is increased. When the voltage becomes high and becomes equal to the 41 constant voltage diode voltage, the current flows through the 41 constant voltage diode for the first time. After that, 41 constant voltage diodes and 43 LEDs flow, so that 43 LEDs cannot be completely protected from inrush current, and 43 LEDs have the disadvantage of deteriorating.

  Also, if the forward voltage at the maximum current of the 43 LEDs exceeds the maximum current of the 43 LEDs due to the variation in the characteristics of the 41 constant voltage diodes, the temperature characteristics of the 43 LEDs, etc., the current that originally flows through the 43 LEDs is the constant voltage of 41 There is also a risk of flowing through the diode.

Prior literature (3)

As for FIG. 7, this circuit uses 48 capacitors as a current limiting element of 51 LEDs to improve efficiency. However, since there is no inrush current prevention circuit, the voltage is divided by the resistors R ₁ R ₂ of 47 and 49 and then full-wave rectified by 50 rectifiers to drive 51 LEDs. Therefore, the loss of the resistors 47 and 49 is increased, the power consumption is increased, and the LED at the start of lighting is a short time, but a current larger than the current at the steady state flows, causing deterioration of the LED 51. There are drawbacks.

Prior literature (4)

  With respect to FIG. 8, this circuit uses 57 capacitors as current limiting elements to improve efficiency. However, since an inrush current always flows through 62 LEDs having a low terminal voltage in the initial stage, it is necessary to insert 61 current limiting resistors in series. Therefore, the loss of 58 resistors is added to the loss of 61 current limiting resistors, which reduces the efficiency and causes inrush current to flow through 62 LEDs.

Prior literature (5)

  With respect to FIG. 9, this circuit uses only 66 capacitors as current limiting elements. Extremely high efficiency is obtained. However, the 68 LEDs are destroyed by the inrush current that flows at the start of lighting, making it difficult to put into practical use. Also, since 68 LEDs are lit in half wave, flicker is also a problem.

Prior literature (6)

  With respect to FIG. 10, this circuit reduces losses and improves efficiency, but the method is quite different. In order to drive 72 LED units, 73 constant current circuits are used. The voltage applied to the constant current circuit is automatically controlled by the minimum voltage detection device 74 so as to apply the minimum voltage capable of constant current operation, thereby increasing the efficiency.

Prior literature (7)

  As for FIG. 11, this circuit aims to improve efficiency, but the circuit system is different. As a switching element, power loss is reduced by a phase control circuit using 82 thyristors.

List of the above prior art documents

Prior Art (1) Circuit Diagram 1 of Japanese Patent Application Laid-Open No. 2007-59247 (FIG. 4)
Prior Art (1) Circuit Diagram 2 of Japanese Patent Application Laid-Open No. 2007-59247 (FIG. 5)
Prior Art (2) Circuit diagram of Japanese Patent Laid-Open No. 11-97747 (FIG. 6)
Prior Document (3) Circuit diagram of Japanese Patent Laid-Open No. 2008-107370 (FIG. 7)
Prior Art (4) Circuit diagram of Japanese Patent Laid-Open No. 2000-306865 (FIG. 8)
Prior Art (5) Circuit diagram of Japanese Patent Laid-Open No. 2003-332625 (FIG. 9)
Prior Document (6) Circuit diagram of JP-A-2006-278304 (FIG. 10)
Prior Document (7) Circuit diagram of JP-A-6-242733 (FIG. 11)

It is humankind's responsibility to prevent global warming by reducing greenhouse gas CO ₂ . Energy saving is also promoted in the field of lighting, and prior art documents relating to lighting fixtures and lighting devices using LEDs as light sources have been published, and products are also commercially available. However, although it has greatly saved energy compared to conventional incandescent bulbs, it is still not enough when considering efficiency.
The present invention relates to an electronic circuit for lighting an LED with a commercial power source or other AC power source with high efficiency without generating noise.

  To provide a stable lighting circuit that protects an LED from an inrush current that flows excessively at the start of lighting and a high efficiency by using a capacitive reactance element in an LED lighting circuit using a commercial power supply or an AC power supply With the goal.

  In order to solve the above-described problem, a capacitive reactance (a low-loss capacitor) is mainly used as a current limiting element that determines a steady-state current value flowing through the LED. However, an excessively large inrush current for charging the capacitive reactance element flows at the start of LED lighting, and the LED is damaged as shown in the prior art (5). In order to prevent this, the inrush current is bypassed by the varistor element only at the start of lighting. In addition, current is not supplied to the varistor during steady operation.

  Thus, the current flowing through the LED keeps the transistor connected in series with the LED in a cut-off state and does not flow while the inrush current is excessively flowing. After charging of the capacitive reactance element is completed, a steady-state current is allowed to flow through the LED.

  Thus, according to the present invention, as shown in the prior art (1), (3), and (4), the current limiting element has almost capacitive reactance without using a current limiting resistor that causes loss. In order to protect the LED from excessive inrush current without flowing the inrush current as shown in prior documents (1), (2), (3), (4), It is possible to provide a safe LED lighting circuit with few failures.

  Further, since a phase control circuit, a high-frequency switching circuit and the like as shown in the prior document (7) are not used in the circuit, no high-frequency noise is generated.

A miniature light bulb used as a night light in ordinary homes is about 5 W, and the power consumption of the three LEDs when using the lighting circuit of the present invention that obtains the same brightness is 1/20 as shown in FIG. It is about 0.25W. Since a highly efficient AC LED light bulb lighting circuit that can be used for other lighting devices in general can be provided, it can contribute to the reduction of greenhouse gas CO ₂ and contribute to the prevention of global warming.

  As an example, the total power consumption is about 500,000 kW when there are about 50 million households in Japan and two nightlight bulbs 5W are used in each house. In the lighting circuit of the present invention, the power consumption when using three LEDs at a brightness is 0.25 W, and when two LEDs are used, the power consumption is 0.5 W, and the power consumption is 25,000 kW for all stations. The reduction effect of 475,000 kW can be expected.

These are the circuit diagrams of one Example of this invention. These are the external appearance of the LED bulb of one Example of this invention. These are graphs showing the relationship between the power supply voltage and the power consumption of the circuit using three LEDs according to one embodiment of the present invention.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram. Reference numeral 3 denotes a capacitive reactance element (low loss capacitor) that determines the value of the current flowing through the LED in a steady state.

  A varistor 8 is used for the purpose of bypassing an excessive inrush current that flows excessively at the start of lighting. The varistor voltage is selected to be higher than the sum of the forward voltage of the 7 LEDs in the steady state and the saturation voltage of the 9 transistors. In the steady state, the current flows only to the 7 LEDs and flows to the 8 varistors. I am trying not to.

  The 12 resistors are for determining the maximum value of the inrush current flowing through the varistor. Since the peak allowable current value of the varistor No. 8 is large, the value of the resistance value of 12 can be set very low compared to the value of the capacitive reactance of 3, so that high efficiency can be realized.

  The resistors 6 and 10 determine the base current of the 9 transistors and, in combination with the 11 capacitors, form a delay circuit that delays the start of conduction of the 9 transistors during the inrush current flow time.

  As a result, while the inrush current is flowing, the 9 transistor is cut off, protecting the LED from the inrush current. In a steady state, a steady current continues to flow through the LED.

  The resistor 10 determines the base current and delay time of the transistor 9, and discharges the capacitor 11 when the connection to the commercial power supply or other AC power supply is cut off, and the next lighting starts. This is to prepare for the inrush current at the time.

  The charging time constant determined from 11 capacitors and 6 and 10 resistors is selected to be larger than the time during which the inrush current flows, and the discharging time constant is made as small as possible.

  The time of inrush current flowing at the start of lighting is obtained from the capacitance value of the capacitive reactance element of approximately 3, the resistance value of 12 resistors, and the impedance of the commercial power supply or AC power supply.

  The resistor 4 is for discharging the charge charged in the capacitive reactance element 3 and is connected for the purpose of preventing electric shock.

  The fuse No. 2 is provided for an excessive current that flows when a malfunction occurs in the lighting circuit, and is used for safety purposes. The fuse of 2 is not limited to the current operation type fuse, and a temperature operation type fuse may be used. Reference numeral 5 denotes a diode bridge rectifier circuit.

  As described above, the varistor 8 is used to flow an inrush current that flows excessively, and a bidirectional or unidirectional noise absorbing diode may be used. In addition, the transistor 9 has a switching action, and it is a matter of course that not only a bipolar transistor but also an FET may be used.

  In the embodiment of FIG. 1, the number of LEDs can correspond to about 1 to 24 in the case of a commercial power supply of 100V. Naturally, it can support 200V line. Depending on the number of LEDs used, the capacity of the capacitive reactance element of 3, the operating voltage value of 8 varistor, the resistance value of 6 resistor, the capacity of 11 capacitor, etc. need to be changed. In order to further increase the number of LEDs, a plurality of the circuits can be used.

Industrial applicability

  The present invention, as a new high-efficiency lighting circuit for LED bulbs that replace incandescent bulbs, is naturally applicable to household lighting fixtures and devices, but lighting devices can be used in public facilities, offices, factories, transportation facilities, etc. It can be used in all fields, and can greatly contribute to energy reduction in each field.

1 Commercial power supply or other AC power supply 2 Normal blown type or thermal fuse 3 Capacitive reactance element (low loss capacitor)
4 Discharge resistor 5 Rectifier diode or diode bridge 6 Delay time and bias current setting resistor 7 LED
8 Varistor or noise absorbing diode 9 Transistor or FET
DESCRIPTION OF SYMBOLS 10 Discharge resistor 11 Delay time setting capacitor 12 Inrush current maximum value setting resistor 13 Inrush current flow direction 14 Steady current flow direction 15 Inrush current prevention circuit 16 Appearance of three types of LED bulbs using the lighting circuit of the present invention 17 Power supply voltage vs. power consumption characteristics of three lighting circuits LED of the present invention

Claims (1)

  In an LED lighting circuit that uses a commercial power source or other AC power source, a capacitive reactance is used as an LED current limiting element to increase energy efficiency and excessively flow into the capacitive reactance element at the start of lighting Bypassing the inrush current to the varistor circuit and delaying the start of conduction of the transistor connected in series with the LED while the inrush current flows through the varistor, the steady current flows after the inrush current stops flowing to the LED. , High-efficiency lighting circuit that protects LEDs from inrush current.