Led lighting device and illumination fixture

The present invention relates to an LED lighting device and a luminaire for lighting a light emitting diode.

An LED lighting device is known in which an inductor is excited by a DC power supply and a regenerative current due to electromagnetic energy stored in the inductor is passed through a light emitting diode when the DC power supply is turned off to light the light emitting diode with high efficiency. For example, a series circuit of an inductor and a light emitting diode is connected to a DC power supply via a switching element, connected in parallel to this series circuit, and LED lighting having a diode forming a closed circuit with the series circuit when the switching element is turned off. The device is known (see, for example, Patent Document 1). This conventional technique is a separately excited LED lighting device, and the switching means is controlled on and off by a PG (control means).

Further, an LED lighting device has been proposed in which a boost chopper provided with an inductor, a switching element and a diode is connected to a DC power supply, and a light emitting diode is lit by the DC output of the boost chopper (see, for example, Patent Document 2). .. This prior art is separately excited and includes a feedback circuit that feeds back the current (LED current) flowing through the light emitting diode and a detection circuit that detects the current (switching current) flowing through the switching element, and the control circuit is the LED current and switching current. The switching element is controlled on and off according to the above.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2002-184588 (Page 3, Fig. 1)</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2001-313423 (pages 5-6, Fig. 1)</text></patcit>

<p> In Patent Document 1 and Patent Document 2, in order to constantly control the current flowing through the light emitting diode, the current flowing through the light emitting diode is detected, and the control circuit controls the switching element on and off according to the detection. There is a drawback that the circuit configuration becomes complicated and expensive.</p><p> An object of the present invention is to provide a self-excited LED lighting device and a luminaire for lighting a light emitting diode with high efficiency.</p>

<p> The invention of the LED lighting device according to claim 1 includes a DC power supply; an inductor excited by the DC power supply; a light emitting diode connected in series with the DC power supply together with the inductor; a DC power supply, an inductor and a light emitting diode. With the first switching element that opens and closes the connection; with the diode connected to form a closed circuit with the inductor and the light emitting diode when the first switching element is off; the current that correlates with the current flowing through the light emitting diode. With a feedback circuit that returns to the control terminal of the first switching element to turn on the first switching element; is connected in series to the output terminal of the first switching element and detects the current flowing through the first switching element. The current detecting means is connected to the control terminal and the output terminal of the first switching element via the current detecting means, and the current is generated from the control terminal side of the first switching element according to the current detected by the current detecting means. It is characterized by including a second switching element; which changes the current fed back to the control terminal of the first switching element by the flow and feedback circuit to change the on-period of the first switching element. ..</p><p> Unless otherwise specified, in the present invention and each of the following inventions, each configuration is as follows.</p><p> The DC power supply may be a battery, one in which the AC voltage is rectified or rectified and smoothed, or one in which a chopper circuit is formed in the rectified and smoothed circuit and smoothed, or the like, which outputs a DC voltage.</p><p> The light emitting diode may be either a surface mount type or a bullet type. Further, it may be one or a plurality, and in the case of a plurality, a series connection or a series-parallel connection is allowed.</p><p> According to the present invention, a current flows through the second switching element according to the current flowing through the first switching element, and the current fed back to the control terminal of the first switching element is changed by the feedback circuit. The on / off frequency of the switching element is changed.</p><p> The invention of the LED lighting device according to claim 2 includes a DC power supply, an inductor excited by a current supplied from the DC power supply, a light emitting diode connected in series with the DC power supply together with the inductor, and a DC power supply. With a first switching element that opens and closes the connection between the inductor and the light emitting diode; when the first switching element is off, the electromagnetic energy stored in the inductor is connected so as to form a closed circuit together with the inductor and the light emitting diode. With a diode that circulates the current due to the current in the closed circuit; and with a feedback circuit that feeds back the current that correlates with the current flowing through the light emitting diode to the control terminal of the first switching element and turns on the first switching element; A resistor connected in series with the output terminal of the switching element to detect the current flowing through the first switching element; and a resistor connected via the resistor between the control terminal and the output terminal of the first switching element. A current is passed from the control terminal side of the first switching element according to the voltage across the ends, and the current fed back to the control terminal of the first switching element by the feedback circuit is changed to change the on period of the first switching element. It is characterized by having a second switching element and;</p><p> According to the present invention, a current flows from the control terminal side of the first switching element to the second switching element according to the voltage across the resistor generated by the current flowing through the first switching element, and the first by the feedback circuit. Since the current fed back to the control terminal of the switching element is changed, the on / off frequency of the first switching element is changed.</p><p> The invention of the LED lighting device according to claim 3 includes a DC power supply; an inductor excited by the DC power supply; a light emitting diode connected in series with the DC power supply together with the inductor; a DC power supply, an inductor and a light emitting diode. With a switching element that opens and closes the connection; with a diode connected to form a closed circuit with the inductor and the light emitting diode when the switching element is off; the control terminal of the switching element that correlates with the current flowing through the light emitting diode. A feedback circuit that feeds back to and turns on the switching element; a first resistor connected in series to the output terminal of the switching element; and a first resistor connected between the control terminal and output terminal of the switching element. It is characterized by having a high-impedance second resistor that acts so as to change the voltage between the control terminal and the output terminal of the switching element according to the current flowing through the first resistor.</p><p> Since the second resistor has a high impedance, the voltage between the control terminal and the output terminal of the switching element changes according to the voltage across the first resistor. Then, the voltage across the first resistor changes according to the current flowing through the first resistor.</p><p> According to the present invention, the voltage between the control terminal and the output terminal of the switching element is changed according to the current flowing through the first resistor, and the on / off frequency of the switching element is changed.</p><p> The invention of the luminaire according to claim 4 is characterized by comprising the LED lighting device according to any one of claims 1 to 3; and a luminaire main body in which the LED lighting device is arranged; And.</p><p> According to the present invention, since the self-excited LED lighting device in which the current flowing through the light emitting diode is controlled to be constant is provided, the lighting equipment can be formed at low cost.</p>

<p> According to the invention of claim 1, the current fed back to the control terminal of the first switching element by the feedback circuit is changed according to the current flowing through the first switching element, and the on / off frequency of the first switching element is changed. Since it is changed, the current flowing through the light emitting diode can be controlled to be constant by the self-excited lighting circuit.</p><p> According to the invention of claim 2, a current flows from the control terminal side of the first switching element to the second switching element according to the voltage across the resistor generated by the current flowing through the first switching element, and the feedback circuit is used. Since the current fed back to the control terminal of the first switching element is changed and the on / off frequency of the first switching element is changed, the current flowing through the light emitting diode can be controlled to be constant by the self-excited lighting circuit. ..</p><p> According to the invention of claim 3, the voltage between the control terminal and the output terminal of the switching element is changed according to the current flowing through the first resistor connected in series with the switching element, and the on / off frequency of the switching element is changed. Is changed, so that the current flowing through the light emitting diode can be controlled to be constant by the self-excited lighting circuit.</p><p> According to the invention of claim 4, since the LED lighting device according to any one of claims 1 to 3 is provided, which is self-excited and in which the current flowing through the light emitting diode is controlled to be constant, an inexpensive lighting fixture is provided. can do.</p>

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, the first embodiment of the present invention will be described.

FIG. 1 is a circuit diagram of an LED lighting device showing the first embodiment of the present invention. The LED lighting device 1 includes a DC power supply 2, a lighting circuit unit 3, and a light emitting diode 4. The DC power supply 2 is formed so as to output a DC voltage by rectifying and smoothing a commercial AC voltage, for example. The lighting circuit unit 3 lights the light emitting diode 4. A plurality of light emitting diodes 4 are connected in series, and when a current flows, for example, white light is emitted.

The lighting circuit unit 3 has an inductor L1, a field effect transistor FET1 as a first switching element, a diode D1, a feedback circuit 5, a resistor R1 as a current detecting means, and a bipolar transistor Tr1 as a second switching means. It is configured.

The inductor L1 is connected in series with the light emitting diode 4 and in series with the DC power supply 2. The inductor L1 is excited by the current supplied from the DC power supply 2, and electromagnetic energy is stored.

The field effect transistor FET1 is connected between the DC power supply 2 and the series circuit of the inductor L1 and the light emitting diode 4, and opens and closes the connection between the DC power supply 2 and the inductor L1 and the light emitting diode 4. The diode D1 is connected in parallel with the series circuit of the inductor L1 and the light emitting diode 4, and forms a closed circuit together with the series circuit when the field effect transistor FET1 is off.

The feedback circuit 5 consists of a secondary winding L1b of the inductor L1, a resistor R2 connected in series with the secondary winding L1b, and a parallel circuit of the capacitor C1. The field effect transistor FET1 side of the primary winding L1a of the inductor L1. It is connected between one end of the circuit and the control terminal of the field effect transistor FET1. The feedback circuit 5 feeds back the current flowing through the inductor L1, that is, the current correlating with the current flowing through the light emitting diode 4, to the control terminal of the field effect transistor FET1 to turn on the field effect transistor FET1. Here, the parallel circuit of the resistor R2 and the capacitor C1 adjusts the timing and the amount of current to flow the feedback current to the control terminal of the field effect transistor FET1.

Then, in parallel with the feedback circuit 5, the diode D2 is connected so that the cathode is on the control terminal side of the field effect transistor FET1. The feedback circuit 5 and the diode D2 form a closed circuit. Then, when the field-effect transistor FET1 is turned off, the charge accumulated in the control terminal of the field-effect transistor FET1 is drawn out, and the charge charge of the capacitor C1 is discharged in the closed circuit.

Then, a starting resistor R3 is connected between the input terminal (drain) and the control terminal (gate) of the field effect transistor FET1. The resistor R3 supplies a starting current to the control terminal of the field-effect transistor FET1 when the DC power supply 2 is turned on to turn on the field-effect transistor FET1.

The resistor R1 as a current detecting means is connected in series between the field effect transistor FET1 and the inductor L1 to the output terminal (source) of the field effect transistor FET1. The resistor R1 detects the current flowing through the field effect transistor FET1. That is, a voltage corresponding to the current is generated between both ends of the resistor R1.

The bipolar transistor Tr1 as the second switching means is connected to the control terminal (gate) and the output terminal (source) of the field effect transistor FET1 via the resistor R1. That is, the collector of the bipolar transistor Tr1 is connected to the control terminal of the field effect transistor FET1, and the resistor R1 is connected between the emitter and the base. As a result, the voltage across the resistor R1 is applied to the base of the bipolar transistor Tr1.

In the bipolar transistor Tr1, a current flows from the collector side to the emitter side according to the voltage across the resistor R1. Since the emitter of the bipolar transistor Tr1 is connected to the control terminal of the field effect transistor FET1 and the feedback current is supplied to this control terminal by the feedback circuit 5, the feedback current is changed according to the voltage across the resistor R1. Since the voltage across the resistor R1 is generated by the current flowing through the resistor R1, that is, the current flowing through the field effect transistor FET1, the field effect transistor by the feedback circuit 5 depends on the current flowing through the resistor R1 (the current flowing through the field effect transistor FET1). The current (feedback current) fed back to the control terminal of FET1 is changed. Then, the on-off period or the off-period of the field-effect transistor FET1 is changed by the change of the feedback current, and the on-off frequency is changed.

The resistor R1 as the current detecting means also serves as a resistor for limiting current.

A smoothing capacitor C2 and a resistor R4 are connected in parallel with the light emitting diode 4 between the inductor L1 and the light emitting diode 4. The smoothing capacitor C2 and resistor R4 confirm the connection of, for example, the light emitting diode 4. That is, when the light emitting diode 4 does not light even though the DC power supply 2 is turned on, and a predetermined voltage is detected between both ends of the smoothing capacitor C2 and the resistor R4, the lead connected to the light emitting diode 4 is detected. It can be confirmed that the light emitting diode 4 is not connected, for example, the wire is broken.

Next, the operation of the LED lighting device 1 will be described.

When the DC power supply 2 is turned on, the field effect transistor FET1 is turned on by the start-up resistor R3. Then, when the field-effect transistor FET1 is turned on, the current supplied from the DC power supply 2 flows through the path of the field-effect transistor FET1, the resistor R1, the inductor L1 and the light emitting diode 4, the light emitting diode 4 lights up, and the inductor L1 is lit. Electromagnetic energy is stored. At this time, the feedback current flows through the control terminal of the field effect transistor FET1 by the feedback circuit 5, and the field effect transistor FET1 keeps on.

Then, when a predetermined current flows through the field-effect transistor FET1, the field-effect transistor FET1 is turned off. Then, a current flows through the closed circuit of the feedback circuit 5 and the diode D2, and the electric charge accumulated in the control terminal of the field effect transistor FET1 is extracted by the feedback current, and the electric charge of the capacitor C1 is discharged.

Further, the current due to the electromagnetic energy stored in the inductor L1 flows in the closed circuit of the inductor L1, the light emitting diode 4 and the diode D1, the light emitting diode 4 lights up, and the electromagnetic energy of the inductor L1 is consumed. Since the light emitting diode 4 is lit by the regenerative current due to the electromagnetic energy stored in the inductor L1, the light emitting diode 4 is lit with high efficiency. Then, when a current is flowing through the inductor L1, a feedback current flows through the feedback circuit 5, and this feedback current is delayed and supplied to the control terminal of the field effect transistor FET1 to turn on the field effect transistor FET1. Hereinafter, the above is repeated.

Then, a current flows from the collector of the bipolar transistor Tr1 to the emitter according to the current flowing through the resistor R1 (voltage across the resistor R1), and the feedback current supplied to the control terminal of the field effect transistor FET1 is changed by the feedback circuit 5. To. As a result, the on-off period or the off-period of the field-effect transistor FET1 is changed to change the on-off frequency. Then, the on / off frequency of the field effect transistor FET1 is changed according to the current flowing through the resistor R1, so that the current flowing through the light emitting diode 4 is controlled to a preset constant current.

Next, a second embodiment of the present invention will be described.

FIG. 2 is a circuit diagram of an LED lighting device showing a second embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In the LED lighting device 6 shown in FIG. 2, in the LED lighting device 1 shown in FIG. 1, the diode D1 and the inductor L1 are connected so that the resistor R1 as the current detecting means is connected to the connection point A1 of the field effect transistor FET1 and the diode D1. It is connected in between.

A current flowing through the field effect transistor FET1 or a current due to electromagnetic energy stored in the inductor L1 flows through the resistor R1. Then, as in the LED lighting device 1 shown in FIG. 1, a current flows from the collector side to the emitter side of the bipolar transistor Tr1 according to the current flowing through the resistor R1, the on / off frequency of the field effect transistor FET1 is changed, and the light emitting diode 4 The current flowing through the current is controlled to a preset constant current.

Next, a third embodiment of the present invention will be described.

3 to 4 are circuit diagrams of an LED lighting device showing a third embodiment of the present invention. The same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

The LED lighting device 7 shown in FIG. 3 is the LED lighting device 1 shown in FIG. 1 in which a resistor R5 for limiting current is connected between the connection point A2 of the resistor R1 and the inductor L1 and the diode D1. The resistor R5, together with the resistor R1, sets the current flowing through the light emitting diode 4 to a predetermined current value.

Further, the LED lighting device 8 shown in FIG. 4 is an LED lighting device 6 shown in FIG. 2 in which a resistor R6 for limiting current is connected between the connection point A1 of the field effect transistor FET1 and the resistor R1 and the diode D1. Is. The resistor R6, together with the resistor R1, sets the current flowing through the light emitting diode 4 to a predetermined current value.

In the first to third embodiments, the field-effect transistor FET1 as the first switching element may be a bipolar transistor, and the bipolar transistor Tr1 as the second switching element is a field-effect transistor. It may be.

Next, a fourth embodiment of the present invention will be described.

FIG. 5 is a circuit diagram of an LED lighting device showing a fourth embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

In the LED lighting device 9 shown in FIG. 5, in the LED lighting device 1 shown in FIG. 1, a resistor R7 as a first resistor is connected instead of a resistor R1 as a current detecting means, and a bipolar as a second switching means is connected. A second resistor R8 is connected in place of the transistor Tr1. That is, the resistor R7 is connected in series to the output terminal (source) of the field-effect transistor FET1 and is inserted between the field-effect transistor FET1 and the connection point A3 of the inductor L1 and the diode D1. Further, the resistor R8 is connected to the control terminal (gate) and the output terminal (source) of the field effect transistor FET1 via the resistor R7. The resistor R8 has a high resistance value (high impedance), for example, 100 KΩ.

Further, instead of the feedback circuit 5, the feedback circuit 10 including the secondary winding L1b of the inductor L1, the resistor R9, and the series circuit of the capacitor C3 is the field effect transistor FET1 side of the primary winding L1a of the inductor L1 and the electric field. Effect It is connected between the control terminals of the transistor FET1.

The feedback circuit 10 feeds back the current flowing through the inductor L1, that is, the current correlating with the current flowing through the light emitting diode 4, to the control terminal of the field effect transistor FET1 to turn on the field effect transistor FET1. Further, when the field-effect transistor FET1 is turned off, the charge charge of the capacitor C3 is discharged in the closed circuit with the diode D2, and the charge accumulated in the control terminal of the field-effect transistor FET1 is drawn out.

Further, a smoothing capacitor C2 is connected in parallel with the light emitting diode 4 between the inductor L1 and the light emitting diode 4.

Of the resistors R7 and R8 connected between the control terminal (gate) and output terminal (source) of the field-effect transistor FET1, the resistor R8 has a high impedance, so that the control terminal of the field-effect transistor FET1 and the resistor R8 The voltage between the output terminals acts so as to change substantially depending on the voltage across the resistor R7. Then, the current flowing through the field effect transistor FET1 flows through the resistor R7, and a voltage corresponding to the current is generated between both ends of the resistor R7.

Then, when the current flowing through the field effect transistor FET1 changes, the voltage across the resistor R7 changes. As a result, the voltage between the control terminal and the output terminal of the field effect transistor FET1 changes, so that the on period or the off period of the field effect transistor FET1 is changed, and the on / off frequency is changed. As a result, the current flowing through the light emitting diode 3 is controlled to a preset constant current.

As described above, the on / off frequency of the field effect transistor FET1 is changed according to the current flowing through the resistor R7, so that the current flowing through the light emitting diode 4 is controlled to a preset constant current.

The resistor R7 as the first resistor also serves as a resistor for limiting current.

Next, a fifth embodiment of the present invention will be described.

FIG. 6 is a circuit diagram of an LED lighting device showing a fifth embodiment of the present invention. The same parts as those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

The LED lighting device 11 shown in FIG. 6 connects the diode D1 and the inductor in the LED lighting device 9 shown in FIG. 5 so that the resistor R7 as the first resistor is connected to the connection point A4 of the field effect transistor FET1 and the diode D1. It is connected between L1.

A current flowing through the field effect transistor FET1 or a current due to electromagnetic energy stored in the inductor flows through the resistor R7. Then, as in the LED lighting device 9 shown in FIG. 5, the on / off frequency of the field effect transistor FET1 is changed according to the current flowing through the resistor R7, so that the current flowing through the light emitting diode 4 is a preset constant current. Is controlled by.

Next, a sixth embodiment of the present invention will be described.

7 to 8 are circuit diagrams of an LED lighting device showing a sixth embodiment of the present invention. The same parts as those in FIGS. 5 to 6 are designated by the same reference numerals, and the description thereof will be omitted.

The LED lighting device 11 shown in FIG. 7 is the LED lighting device 9 shown in FIG. 5 in which a resistor R9 for limiting current is connected between the connection point A3 of the resistor R7 and the inductor L1 and the diode D1. The resistor R9, together with the resistor R7, sets the current flowing through the light emitting diode 4 to a predetermined current value.

The LED lighting device 13 shown in FIG. 8 is the LED lighting device 11 shown in FIG. 6 in which a resistor R10 for limiting current is connected between the connection point A4 of the field effect transistor FET1 and the resistor 7 and the diode D1. .. The resistor R10, together with the resistor R7, sets the current flowing through the light emitting diode 4 to a predetermined current value.

In the fourth to sixth embodiments, the field effect transistor FET1 as the switching element may be a bipolar transistor.

Next, a seventh embodiment of the present invention will be described.

FIG. 9 is a schematic side view of a partially cutout of the LED lighting fixture showing the seventh embodiment of the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

The luminaire 14 shown in FIG. 9 is a directly attached luminaire arranged on the ceiling surface 15, and includes the LED lighting device 1 shown in FIG. 1 and the luminaire main body 16.

The luminaire main body 16 has an opening 16a on the lower surface and is formed in a box shape, and a substrate 17 is arranged inside. A plurality of light emitting diodes 4 connected in series are arranged on the substrate 17 so as to face the opening 16a. The luminaire body 16 is supported by the adapter 19 by connecting tubes 18 and 18 having a predetermined length provided on the upper surface side.

The adapter 19 is formed in a substantially columnar shape, and houses the LED lighting device 20 inside. The LED lighting device 20 is obtained by removing the light emitting diode 4 from the LED lighting device 1. The adapter 19 is connected to a hook ceiling 21 arranged on the ceiling surface 15. Then, the lead wires 22 and 22 are derived from the output terminal of the LED lighting device 20, and the lead wires 22 and 22 are connected to the substrate 17 through the connecting tubes 18 and 18.

In the lighting fixture 14, the current flowing through the light emitting diode 4 is controlled to be constant by the control of the LED lighting device 20, and the synchrotron radiation from the light emitting diode 4 is made constant. Further, since it is provided with the self-excited LED lighting device 1, it can be formed at low cost.

The luminaire body 16 is not limited to a box shape, and may have a circular shape or any other shape. Further, the luminaire 14 is not limited to the direct-mounted luminaire, and its use is not limited to a hanging luminaire, an embedded luminaire such as a downlight, and the like.

<figref num="1">The circuit diagram of the LED lighting apparatus which shows the 1st Embodiment of this invention.</figref><figref num="2">The circuit diagram of the LED lighting apparatus which shows the 2nd Embodiment of this invention.</figref><figref num="3">The circuit diagram of the LED lighting apparatus which shows the 3rd Embodiment of this invention.</figref><figref num="4">Similarly, a circuit diagram of another LED lighting device.</figref><figref num="5">The circuit diagram of the LED lighting apparatus which shows the 4th Embodiment of this invention.</figref><figref num="6">The circuit diagram of the LED lighting apparatus which shows the 5th Embodiment of this invention.</figref><figref num="7">The circuit diagram of the LED lighting apparatus which shows the 6th Embodiment of this invention.</figref><figref num="8">Similarly, a circuit diagram of another LED lighting device.</figref><figref num="9">FIG. 6 is a schematic side view of a partial cutout of a lighting fixture showing a seventh embodiment of the present invention.</figref>

Code description

D1 ... Diode FET1 ... 1st switching element or field effect transistor as switching element L1 ... Inductor R1 ... Resistance as current detection means R7 ... 1st resistance R8 ... 1st 2 resistance Tr1 ... Bipolar transistor as the second switching element 1,6,7,8,9,11,12,13 ... LED lighting device 2 ... DC power supply 4 ... Light emitting diode 5 , 10 ... Feedback circuit 14 ... Lighting equipment 16 ... Lighting equipment body