JPH10321914A - Light-emitting equipment and illumination equipment using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain input current higher harmonics, improve efficiency and power factor, eliminate flickers from light emission of a light-emitting diode, and realize proper light-emitting operation. SOLUTION: A filter capacitor 14 is connected with a ripple voltage source via an impedance circuit 13 source of which is obtained by full-wave rectification of an AC power source 11 through a full-wave rectifier circuit 12. A light- frequency inverter circuit 15 is connected with a DC voltage from the filter capacitor as a power source. A circuit, wherein a pair of light-emitting diode groups 16, 17 formed by connecting a plurality of light-emitting diodes LEDs in series and connected in parallel with reverse polarity, is connected with output terminals of the high-frequency inverter circuit 15. A part of high-frequency output of the circuit 15 is applied to the positive pole side of the output terminals of the full-wave rectifier circuit 12, and gives high frequency oscillation. The electric potential of the positive pole side is constituted to be temporarily lower than the voltage of the AC power source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device using a light emitting diode and a lighting device using the light emitting device.

[0002]

2. Description of the Related Art As a light emitting device using a light emitting diode, for example, as shown in FIG. 6, a primary winding of a step-down transformer 2 is connected to a commercial power supply 1 of 50 Hz and 100 V. It is known that a smoothing capacitor 4 is connected to a line via a diode 3 and a plurality of series circuits 5 each including a resistor R and a light emitting diode LED are connected between both ends of the smoothing capacitor 4. This device reduces 100V to 5V AC voltage by a step-down transformer 2, rectifies it by a diode 3, and smoothes it by a smoothing capacitor 4 to convert it to a DC voltage. 5 will be applied.

[0003] The resistor R has a current-limiting function of flowing a predetermined current to the light emitting diode LED. Light emitting diode LED
Since the brightness changes depending on the flowing current, the illuminance can be adjusted by changing the value of the resistor R. In this device, assuming that the input voltage is a sine wave of 50 Hz, the input current flows only near the peak of the input voltage because the smoothing capacitor 4 has a relatively large capacity to generate a sufficient smoothed voltage. become. Therefore, the waveforms of the input voltage and the input current are as shown in FIG.

Further, as shown in FIG.
Step-down transformer 7 via the inductor 6 to the commercial power supply 1 of V
A circuit in which a pair of light emitting diode groups 8, 9 in which a plurality of light emitting diodes LED are connected in series to the secondary winding of the step-down transformer 7 have opposite polarities and are connected in parallel. Connected ones are known. In this device, since the current flows alternately through the light emitting diode groups 8 and 9, the light emitting diode LED blinks at 100 Hz.

In this device, if the input voltage is a sine wave of 50 Hz, the input current to the parallel circuit of the light emitting diode groups 8 and 9 becomes a substantially sine wave due to the inductor 6, but the phase is delayed. In addition, since the inductor 6 acts on 50 Hz, the inductance needs to be about 20 mH to 100 mH. Therefore, the input voltage, the light emitting diode L
Each waveform of the output of the ED and the input current to the light emitting diode LED is as shown in FIG.

[0006]

In the former device shown in FIG. 6, the current flowing through the light emitting diode LED is substantially constant because the smoothing capacitor 4 having a large capacity is provided. Don't feel as flicker. However, there is a problem that the input current waveform has a needle shape, which includes many harmonic components and a large peak current. If the harmonic component is large, it adversely affects substation equipment and the like, and if the peak current is large, it adversely affects the operation of a breaker and the like. Further, since the resistor R is connected in series to the light emitting diode LED, there is a problem that power loss occurs due to the resistor and the resistor generates heat. Power loss W due to resistance R at this time
Is given by the following equation, assuming that there are n resistors R and the forward voltage of the light emitting diode LED is 0.7V. Here, DCV is a voltage applied between both ends of a series circuit of the resistor R and the light emitting diode LED, and Rk is a resistance value of the resistor R. Because of the large power loss, high efficiency could not be achieved.

[0007]

(Equation 1)

Further, in the latter device shown in FIG. 8, the input current waveform is substantially sinusoidal because no smoothing capacitor is used, and harmonic components of the current can be suppressed. However, since the inductor 6 is large, the phase is delayed. There is a problem that the power factor becomes worse. Further, since the light emitting diode LED repeats blinking at 100 Hz, there is a problem that the light is perceived as flickering by human eyes.

Therefore, according to the first to third aspects of the present invention, the input current harmonic can be suppressed to a small value, the power efficiency can be improved without power loss, the power factor can be improved, and the light emitting diode can be improved. Provided is a light emitting device capable of performing a favorable light emitting operation without causing the light emission of the human eyes to flicker. Further, according to the second aspect of the present invention, the currents flowing through a pair of light emitting diode groups connected in parallel with opposite polarities can be made equal to each other, and the brightness of light emission is deviated between the light emitting diode groups. Provide no light emitting device.

Further, according to the invention of claim 4, the input current harmonics can be suppressed to a small value, the power efficiency can be improved without power loss, and the power factor can be improved.
Provided is a lighting device capable of performing a favorable lighting operation without causing light emitted from a light emitting diode to be perceived as flicker by human eyes.

[0011]

According to the first aspect of the present invention,
A smoothing capacitor is connected via an impedance circuit to a pulsating voltage source obtained by full-wave rectification of an AC power supply, and a high-frequency inverter circuit is connected using a DC voltage from the smoothing capacitor as a power supply. One or more sets of a circuit in which a pair of light emitting diodes in which the light emitting diodes are connected in series with opposite polarities and connected in parallel are connected, and a part of the high-frequency output of the high-frequency inverter circuit is used as a pulsating voltage source. In which the potential of the positive output terminal is temporarily lower than the voltage of the AC power supply.

According to a second aspect of the present invention, a smoothing capacitor is connected via an impedance circuit to a full-wave rectified pulsating voltage source of an AC power supply, and a high-frequency inverter circuit is connected using a DC voltage from the smoothing capacitor as a power supply. A pair of a plurality of light emitting diode groups in which a plurality of light emitting diodes are connected in series and having a polarity opposite to each other are connected in parallel to the output terminal of the high frequency inverter circuit via a capacitor. There is a light emitting device which is connected as a set and applies a part of the high frequency output of the high frequency inverter circuit to the positive output terminal of the pulsating voltage source to temporarily lower the potential of the positive output terminal from the voltage of the AC power supply.

According to a third aspect of the present invention, there is provided an AC power supply, a full-wave rectifier circuit connected to the AC power supply, a first capacitor connected between output terminals of the full-wave rectifier circuit, and a first inductor. A parallel resonance circuit comprising a second capacitor;
A high-frequency switching element connected between the output terminals of the full-wave rectifier circuit via a parallel resonance circuit, a primary winding of a transformer inserted in series with a first inductor of the parallel resonance circuit, a parallel resonance circuit and high-frequency switching A first diode having a cathode connected to a connection point with the element, and a series circuit including a second inductor and a smoothing capacitor connected between a positive electrode of an output terminal of the full-wave rectifier circuit and an anode of the first diode; And a second diode having a cathode connected between the negative terminal of the output terminal of the full-wave rectifier circuit and the anode of the first diode, with the cathode connected to the anode of the first diode.
There is provided a light-emitting device in which one or a plurality of sets of a circuit in which a pair of light-emitting diodes in which a plurality of light-emitting diodes are connected in series between secondary windings of a transformer are connected in parallel with opposite polarities are set.

According to a fourth aspect of the present invention, in the light emitting device according to the first, second or third aspect, a blue light emitting diode is used as the light emitting diode, and light from the blue light emitting diode is transmitted through a yellow fluorescent material. In the lighting device using the white light as illumination light.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the basic configuration of the light emitting device is such that a smoothing capacitor 14 is connected via an impedance circuit 13 to a pulsating voltage source obtained by full-wave rectifying an AC power supply 11 by a full-wave rectifier circuit 12 comprising a diode bridge. A high frequency inverter circuit 15 is connected to the smoothing capacitor 14 so as to operate using the DC voltage from the smoothing capacitor 14 as a power supply.
For example, one set of a circuit in which a pair of light emitting diode groups 16 and 17 in which a plurality of light emitting diodes LED are connected in series with opposite polarities are connected in parallel with each other is connected to the output terminal 5. A part of the high-frequency output of the high-frequency inverter circuit 15 is applied to the positive terminal of the output terminal of the full-wave rectifier circuit 12, which is the positive output terminal of the pulsating voltage source. In this configuration, this potential is temporarily lower than the voltage of the AC power supply. In addition,
A plurality of pairs of light emitting diode groups may be connected to the output terminal of the high frequency inverter circuit 15.

In this configuration, the potential on the positive side of the output terminal of the full-wave rectifier circuit 12 oscillates at a high frequency due to the high frequency from the high-frequency inverter circuit 15. When the high-frequency vibration acts in the direction of supplying the current, the full-wave rectifier circuit 1
When the high-frequency vibration acts in the direction of drawing the current, the path to the input power supply is cut off by 2 and the voltage after full-wave rectification is reduced to be lower than the input voltage to draw the current through the full-wave rectifier circuit 12. By adjusting this current draw to an amount commensurate with the input voltage, the input current can flow continuously,
Input current harmonics can be reduced.

FIG. 2 is a circuit diagram specifically showing a circuit section of the impedance circuit 13 and the high-frequency inverter circuit 15. A small-capacity noise cut capacitor 18 is connected between output terminals of the full-wave rectifier circuit 12. At the same time, a first capacitor 20 is connected via a diode 19. Further, a parallel resonance circuit 23 including a first inductor 21 and a second capacitor 22 is provided, and a high-frequency switching element 24 is connected between the output terminals of the full-wave rectification circuit 12 via the parallel resonance circuit 23. . The primary winding 25a of the transformer 25 is inserted in series with the first inductor 21 of the parallel resonance circuit 23. That is, the second capacitor 22 is connected to the first inductor 21.
And the primary winding 25a of the transformer 25 are connected in parallel to a series circuit. The high-frequency switching element 24
And a capacitor 26 is connected in parallel. The high-frequency switching element 24 is composed of an FET or the like, and performs a high-frequency switching operation in a well-known self-excited or separately-excited manner.

A cathode of a first diode 27 is connected to a connection point between the parallel resonance circuit 23 and the high-frequency switching element 24, and a positive electrode of an output terminal of the full-wave rectifier circuit 12 and an anode of the first diode 27 are connected. And a series circuit of the second inductor 28 and the smoothing capacitor 14 is connected through the diode 19. A second diode 29 is connected between the negative terminal of the output terminal of the full-wave rectifier circuit 12 and the anode of the first diode 27, with the cathode thereof being the anode of the first diode 27.

The secondary winding 25 of the transformer 25
b, a parallel circuit of the pair of light emitting diode groups 16 and 17 is connected via a DC cut capacitor 30. The diode 19, the first capacitor 20, and the second inductor 28 constitute an impedance circuit 28, and the first inductor 21, the second capacitor 22, the high-frequency switching element 24, the transformer 25, and the capacitor 2
6. The first diode 27 and the second diode 29 constitute the high-frequency inverter circuit 15.

In such a configuration, the voltage from the output terminal of the full-wave rectifier circuit 12 is applied to the high-frequency inverter circuit via the diode 19, and the high-frequency inverter circuit operates. That is, the high-frequency inverter circuit has the first
By turning on and off the high-frequency switching element 24 at a frequency slightly higher than the resonance frequency determined by the circuit of the inductor 21 and the second capacitor 22 and the capacitor 26, the resonance is maintained. Then, a part of the resonance energy is transmitted through the transformer 25 to the light emitting diode group 1.
6 and 17 and the light emitting diode groups 16 and 17
Are consumed by passing a current through each of the light emitting diodes LED. The power consumption is determined by an integrated value of a current flowing through each light emitting diode LED and a forward voltage of the light emitting diode.

FIG. 3 shows the waveform of each part in this operation.
It becomes as shown in. For example, high frequency switching element 2
4 is turned on and off at a high frequency of 60 KHz, that is, when it is turned on and off at the timing shown in FIG. 3A, the current flowing through the high-frequency switching element 24 becomes as shown in FIG. The voltage generated across the high-frequency switching element 24 is as shown in FIG. Then, a pair of light emitting diode groups 16, 17
When the light emission output of each light emitting diode LED is viewed as a whole, it blinks in a sinusoidal manner at a high frequency of 60 KHz as shown in FIG.

On the other hand, when resonance occurs in the high-frequency inverter circuit, a current flows through the first inductor 21 in an alternating manner, and a current flows through the first inductor 21 in reverse. Since this current is blocked by the diode 19, the voltage on the cathode side of the diode 19 increases. This reaction causes the cathode side of the diode 19 to drop below the original voltage. At this time,
When the voltage drops to a voltage lower than the input voltage, current is drawn from the AC power supply 11 side.

In this way, a part of the high-frequency output of the high-frequency inverter circuit is applied to the cathode side of the diode 19, the potential on the cathode side of the diode 19 oscillates at a high frequency, and this potential drops to a voltage lower than the input voltage. Each time, current is drawn from the AC power supply 11 side.

By this operation, the waveform of the input voltage from the AC power supply 11 becomes as shown in FIG. 4A, and the waveform of the input current becomes as shown in FIG. 4B. It becomes a substantially sine wave, and the input harmonic can be suppressed to a small level.
Further, no phase shift occurs between the input voltage and the input current, and therefore, the power factor can be improved. Further, since the light emission of each of the light emitting diodes LED of the light emitting diode groups 16 and 17 blinks at a high frequency of 60 KHz as shown in FIG. 4D, the light emission does not feel as flicker to human eyes, but is continuously lit. A good light emitting operation can be performed by feeling.

Since the parallel circuit of the pair of light emitting diode groups 16 and 17 is connected to the secondary winding 25b of the transformer 25 via the DC cut capacitor 30, the current flowing through each of the light emitting diode groups 16 and 17 is controlled. Can only be exchanged,
Thereby, the currents flowing through the respective light emitting diode groups can be made equal. Therefore, there is no deviation in the brightness of light emission between the light emitting diode groups 16 and 17, and a favorable light emitting operation can be performed.

When a lighting device is constructed using such a light emitting device, a blue light emitting diode is used as each light emitting diode LED of the light emitting diode groups 16 and 17, and as shown in FIG. Is transmitted through a filter 31 containing a yellow fluorescent material to convert the blue light into white light, which is used for illumination.

That is, since blue light has a short wavelength, it is relatively easy to convert it to a longer yellow wavelength. Here, as the filter 31, a filter is used that does not convert all the blue light to yellow, but transmits half of the blue light as it is. The yellow light is light obtained by combining red light and green light. Therefore, the filter 31 combines the converted yellow light and blue light that is transmitted as it is, so that the three primary colors of RGB are combined. That is, the light emitted from the filter 31 becomes white light.

By converting all the light from each of the light emitting diodes of each of the light emitting diode groups 16 and 17 into white light based on such a principle, sufficient illumination light can be obtained, there is no flicker, and the input current can be reduced. It is possible to configure an illuminating device that can reduce the harmonics, increase the efficiency, and improve the power factor.

[0029]

As described above, according to the first to third aspects of the present invention, input current harmonics can be reduced, power efficiency can be improved without power loss, and power factor can be improved. Moreover, it is possible to provide a light emitting device capable of performing a favorable light emitting operation without the light emitted from the light emitting diode being perceived as flickering by human eyes.

According to the second aspect of the present invention, the currents flowing through a pair of light emitting diode groups connected in parallel with opposite polarities can be made equal, and the brightness of light emission between the light emitting diode groups can be increased. According to the fourth aspect of the present invention, it is possible to suppress the input current harmonics, reduce power loss, improve efficiency, and reduce power consumption. Rate can be improved,
In addition, it is possible to provide a lighting device that can perform a good lighting operation without the light emitted from the light emitting diode being perceived as flickering by human eyes.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic circuit configuration illustrating an embodiment of the present invention.

FIG. 2 is a diagram showing a specific circuit configuration of the embodiment.

FIG. 3 is a waveform chart of the operation of the high-frequency switching element and the output of the light-emitting diode in the embodiment.

FIG. 4 is a waveform chart of an input voltage, an input current, and a light-emitting diode output in the embodiment.

FIG. 5 is a diagram illustrating a configuration of a light-emitting portion when the embodiment is used for a lighting device.

FIG. 6 is a circuit configuration diagram showing a conventional example.

FIG. 7 is a waveform chart of an input voltage and an input current in the conventional example.

FIG. 8 is a circuit diagram showing another conventional example.

FIG. 9 is a waveform chart of an input voltage, an input current, and a light emitting diode output in the conventional example.

[Explanation of symbols]

 11 AC power supply 12 Full-wave rectifier circuit 13 Impedance circuit 14 Smoothing capacitor 15 High-frequency inverter circuit 16, 17 Light emitting diode group

Claims (4)

[Claims] A smoothing capacitor is connected via an impedance circuit to a full-wave rectified pulsating voltage source of an AC power supply, and a high-frequency inverter circuit is connected using a DC voltage from the smoothing capacitor as a power supply. One or more sets of a circuit in which a pair of light emitting diode groups in which a plurality of light emitting diodes are connected in series with opposite polarities are connected in parallel to the output terminal are connected, and one of the high frequency outputs of the high frequency inverter circuit is connected. A light emitting device for applying a voltage to the positive output terminal of the pulsating voltage source to temporarily lower the potential of the positive output terminal from the voltage of the AC power supply. 2. A smoothing capacitor is connected via an impedance circuit to a pulsating voltage source obtained by full-wave rectifying an AC power supply, and a high-frequency inverter circuit is connected using a DC voltage from the smoothing capacitor as a power supply. One or more sets of a circuit in which a pair of light emitting diode groups in which a plurality of light emitting diodes are connected in series with opposite polarities are connected in parallel to each other through a capacitor in series with a capacitor are connected to the output terminal. A light emitting device wherein a part of a high frequency output of an inverter circuit is applied to a positive output terminal of the pulsating voltage source to temporarily lower a potential of the positive output terminal from a voltage of the AC power supply. 3. An AC power supply, a full-wave rectifier circuit connected to the AC power supply, a first capacitor connected between output terminals of the full-wave rectifier circuit, a first inductor and a second capacitor. A parallel resonance circuit, a high-frequency switching element connected between output terminals of the full-wave rectifier circuit via the parallel resonance circuit, and a primary winding of a transformer inserted in series with a first inductor of the parallel resonance circuit A first diode having a cathode connected to a connection point between the parallel resonance circuit and the high-frequency switching element; and a first diode connected between a positive electrode of an output terminal of the full-wave rectifier circuit and an anode of the first diode. A series circuit of a second inductor and a smoothing capacitor; and a cathode connected between a negative electrode of an output terminal of the full-wave rectifier circuit and an anode of the first diode. A second diode connected on the side of the transformer, and a pair of light emitting diode groups in which a plurality of light emitting diodes are connected in series between the secondary windings of the transformer are connected in parallel with opposite polarities. A light emitting device, wherein one or more sets are connected as a set. 4. The light emitting device according to claim 1, wherein a blue light emitting diode is used as the light emitting diode, and light from the blue light emitting diode is converted into white light by transmitting a yellow fluorescent material. An illumination device characterized in that the white light is used as illumination light.