WO2017187685A1

WO2017187685A1 - Led power supply device, and semiconductor integrated circuit

Info

Publication number: WO2017187685A1
Application number: PCT/JP2017/002873
Authority: WO
Inventors: 林　正明
Original assignee: 新電元工業株式会社
Priority date: 2016-04-27
Filing date: 2017-01-27
Publication date: 2017-11-02
Also published as: JPWO2017187685A1; JP6648264B2; TW201739319A; TWI625985B

Abstract

[Problem] To provide an LED power supply device with which it is possible to cutback an auxiliary power supply for supplying power to a control circuit for controlling the illumination of an LED lamp, and reduce the size and the manufacturing cost of the device. [Solution] When a dimming signal indicates that an LED lamp is to illuminate, a control circuit of an LED power supply device outputs a control signal to a control terminal of a feedback means so that a current corresponding to the dimming ratio stipulated by the dimming signal flows through the LED lamp. On the other hand, if the dimming signal indicates that the LED lamp is to not illuminate, the control circuit of the LED power supply device outputs a control signal to the control terminal of the feedback means so that the output voltage from a second rectification smoothing circuit becomes equal to a preset voltage lower than the output voltage outputted from the second rectification smoothing circuit when the dimming signal indicates that the LED lamp is to be illuminated.

Description

LED power supply device and semiconductor integrated circuit

The present invention relates to an LED power supply device and a semiconductor integrated circuit.

Conventionally, there is an LED power supply device 100A that controls the dimming rate of the LED lamp X in accordance with the input of a dimming signal (FIG. 3).

As such an LED power supply device 100A, when the LED lamp X configured by the LED element Xa is turned off, the current value of the LED is controlled at a constant current. S1 had to be stopped, and the auxiliary power source S2 was necessary to control the turning off. A technique for solving this problem is disclosed in Patent Document 1. When turning off the LED lamp X, based on a comparison result between a voltage value lower than the lighting start voltage of the LED element Xa set in advance as a reference value and a detection signal of the detection means RXa that detects the voltage of the LED lamp X. The voltage applied to the LED element Xa is set to a constant voltage lower than the lighting start voltage.

Thereby, the LED element Xa can be turned off in the energized state where the main power source S1 outputs an AC voltage.

Special table 2009-189184

However, the above-described conventional LED power supply device 100A requires the auxiliary power supply S2 for supplying power to the control circuit CON that controls the lighting of the LED lamp X via the regulator REG. There was a problem that the manufacturing cost increased.

In the circuit of Patent Document 1, the power supply voltage of the control circuit is often about 3.3V to 15V. However, many LED lamps increase the number of LED lamps connected in series to ensure luminance, and are often about 50V to 250V. In order to obtain a voltage of 3.3V to 15V from an output of 50V to 250V, a regulator is required, and there is a problem that a very large power loss and heat generation occur.

Accordingly, an LED power supply device that can reduce the size of the device and reduce the manufacturing cost by reducing the auxiliary power supply for supplying power to the control circuit that controls the lighting of the LED lamp and the regulator is provided. For the purpose.

An LED power supply device according to an embodiment according to one aspect of the present invention includes:
A primary circuit having a primary coil and outputting an alternating voltage to the primary coil in response to a feedback signal;
A first secondary coil that forms a transformer with the primary coil;
A second secondary coil that constitutes the transformer together with the primary coil and the first secondary coil;
A first rectifying and smoothing circuit connected to the first secondary coil;
An LED lamp connected to the first rectifying and smoothing circuit and including one or a plurality of LED elements connected in series;
Current detection means provided in the first rectifying / smoothing circuit or between the first rectifying / smoothing circuit and the LED lamp;
A second rectifying and smoothing circuit connected to the second secondary coil;
Feedback means connected to the second rectifying and smoothing circuit and outputting the feedback signal to the primary circuit based on a detection signal of the current detecting means and an output voltage of the second rectifying and smoothing circuit;
A dimming signal that is driven by power supplied from the second rectifying and smoothing circuit and that regulates the dimming rate of the LED lamp output from an external dimming unit, a detection signal of the current detection unit, and the first A control circuit for outputting a control signal for controlling the feedback signal to a control terminal of the feedback means according to an output voltage of the rectifying and smoothing circuit of 2,
The control circuit includes:
When the dimming signal indicates lighting of the LED lamp, a control signal is output to the control terminal of the feedback means so that the current of the LED lamp corresponds to the dimming rate specified by the dimming signal,
On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the output voltage of the second rectifying and smoothing circuit is output from the second rectifying and smoothing circuit when the dimming signal indicates that the LED lamp is on. The control signal is output to a control terminal of the feedback means so as to be a preset voltage lower than the output voltage to be output.

In the LED lamp lighting device,
The control circuit includes:
When the dimming signal indicates the lighting of the LED lamp, a control signal is output to the control terminal of the feedback means so that the LED lamp current corresponds to the dimming rate specified by the dimming signal,
On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the output voltage of the second rectifying and smoothing circuit is output from the second rectifying and smoothing circuit when the dimming signal indicates that the LED lamp is on. A control signal is output to the control terminal of the feedback means so that a first voltage lower than the output voltage is an upper limit value and a second voltage lower than the first voltage is a lower limit value. And

In the LED power supply device,
The primary circuit is
When the dimming signal indicates lighting of the LED lamp, the AC voltage is output to the primary coil according to the feedback signal so that the LED lamp current corresponds to the dimming rate specified by the dimming signal. And
On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the AC voltage is applied to the primary voltage according to the feedback signal so that the LED lamp is extinguished and drivable power is supplied to the control circuit. Output to the side coil.

In the LED power supply device,
The control circuit includes:
A dimming circuit that outputs a DC voltage corresponding to a dimming rate specified by the dimming signal;
The DC voltage is input to a non-inverting input terminal, the inverting input terminal is connected to the current detection means, and an operational amplifier that outputs a control signal so that the DC voltage and the detection signal are equal,
A voltage dividing circuit that outputs a divided voltage obtained by dividing the output voltage of the second rectifying and smoothing circuit;
The divided voltage is input to the inverting input terminal, a preset reference voltage is input to the non-inverting input terminal, a control signal is output based on the result of comparing the divided voltage and the reference voltage, and hysteresis characteristics A comparator having
The control circuit includes:
When the dimming signal indicates the lighting of the LED lamp, the control signal output by the operational amplifier is output to the control terminal of the feedback means,
When the dimming signal indicates that the LED lamp is turned off, the control signal output by the comparator is output to the control terminal of the feedback means.

In the LED power supply device,
The control circuit includes:
A first state in which the output of the operational amplifier and the control terminal of the feedback means are conducted when the dimming signal indicates lighting of the LED lamp; and A switching circuit for switching between a second state of conducting the output of the comparator and the control terminal of the feedback means;
The dimming circuit controls the operation of the switching circuit.

In the LED power supply device,
The primary circuit is
When the dimming signal indicates that the LED lamp is extinguished, the primary side according to the feedback signal so as to be less than the voltage obtained by integrating the forward voltage of the LED element and the number of stages of the LED element of the LED lamp. It is characterized by controlling the AC voltage output to the coil.

In the LED power supply device,
The number of turns of the second secondary coil is smaller than the number of turns of the first secondary coil.

In the LED power supply device,
The feedback means is an insulating signal transmission element that insulates and transmits the feedback signal based on the detected current.

In the LED power supply device,
The feedback means is a light emitting diode.

In the LED power supply device,
The primary side circuit includes a passive element that receives the feedback signal and outputs a reception signal corresponding to the received feedback signal.
The primary circuit outputs an AC voltage to the primary coil according to the received signal.

In the LED power supply device,
The passive element is a photodiode or a phototransistor.

In the LED power supply device,
The first rectifying / smoothing circuit includes:
One end is connected to the other end of the first secondary coil, the other end is connected to the first LED terminal, and the other end of the first secondary coil is directed to the first LED terminal. A first rectifying element whose direction is a forward direction;
A first output capacitor having one end connected to the first LED terminal and the other end connected to the second LED terminal;
One end connected to the second LED terminal and the other end connected to one end of the first secondary coil, a current detection resistor as the current detection means,
The second rectifying / smoothing circuit includes:
One end is connected to the other end of the second secondary coil, the other end is connected to the power supply terminal, and the direction from the other end of the second secondary coil toward the power supply terminal is the forward direction. Two rectifying elements;
And a second output capacitor having one end connected to the power supply terminal and the other end grounded.

A semiconductor integrated circuit according to an embodiment of one aspect of the present invention has a primary side coil, and outputs a primary voltage to the primary side coil in response to a feedback signal, the primary side coil, and a transformer Connected to the first secondary coil constituting the transformer, the second secondary coil constituting the transformer together with the primary coil and the first secondary coil, and the first secondary coil. A first rectifying / smoothing circuit, an LED lamp connected to the first rectifying / smoothing circuit and including one or a plurality of LED elements connected in series, and in the first rectifying / smoothing circuit, or Current detecting means provided between the first rectifying / smoothing circuit and the LED lamp, a second rectifying / smoothing circuit connected to the second secondary coil, and the second rectifying / smoothing circuit Connected to the current detection means. Signal, and provides a semiconductor integrated circuit applied to the LED power supply device including a feedback means, a based on the output voltage of the second rectifying smoothing circuit outputs the feedback signal to the primary circuit,
The semiconductor integrated circuit is:
A dimming signal that is driven by power supplied from the second rectifying and smoothing circuit and that regulates the dimming rate of the LED lamp output from an external dimming unit, a detection signal of the current detection unit, and the first A control signal for controlling the feedback signal to the control terminal of the feedback means according to the output voltage of the rectifying and smoothing circuit of No. 2,
When the dimming signal indicates lighting of the LED lamp, a control signal is output to the control terminal of the feedback means so that the current of the LED lamp corresponds to the dimming rate specified by the dimming signal,
On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the output voltage of the second rectifying and smoothing circuit is output from the second rectifying and smoothing circuit when the dimming signal indicates that the LED lamp is on. The control signal is output to a control terminal of the feedback means so as to be a preset voltage lower than the output voltage to be output.

An LED power supply device according to an aspect of the present invention includes a primary side coil that includes a primary side coil and outputs an AC voltage to the primary side coil in response to a feedback signal, and a primary side coil and a transformer that form a first transformer. A secondary side coil, a second secondary side coil that constitutes a transformer together with the primary side coil and the first secondary side coil, a first rectifying and smoothing circuit connected to the first secondary side coil, An LED lamp connected to the first rectifying / smoothing circuit and including one or a plurality of LED elements connected in series, in the first rectifying / smoothing circuit, or between the first rectifying / smoothing circuit and the LED lamp Connected to the second rectifying / smoothing circuit connected to the second secondary coil, the second rectifying / smoothing circuit connected to the current detecting means, and the detection signal of the current detecting means, Based on the output voltage of the rectifying and smoothing circuit, the feedback A dimming signal that is driven by the power supplied from the second rectifying and smoothing circuit and that regulates the dimming rate of the LED lamp that is output from the external dimming means; And a control circuit for outputting a control signal for controlling the feedback signal to the control terminal of the feedback means according to the detection signal of the current detection means and the output voltage of the second rectifying and smoothing circuit.

In particular, when the dimming signal indicates the lighting of the LED lamp, the control circuit outputs the control signal to the control terminal of the feedback means so that the current of the LED lamp corresponds to the dimming rate specified by the dimming signal. On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the output voltage of the second rectifying and smoothing circuit is output from the second rectifying and smoothing circuit when the dimming signal indicates that the LED lamp is on. A control signal is output to the control terminal of the feedback means so as to be a preset voltage lower than the output voltage.

Thereby, when the dimming signal indicates the lighting of the LED lamp, a constant current is supplied to the LED lamp through the first secondary coil so that the LED lamp is lit from the primary circuit, and A driving power supply voltage is supplied to the control circuit via the two secondary coils.

On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the LED lamp is extinguished and drivable power is supplied to the control circuit from the primary side circuit.

As described above, the LED power supply device according to one aspect of the present invention reduces the auxiliary power supply for supplying power to the control circuit that controls the lighting of the LED lamp, thereby reducing the size and manufacturing cost of the device. Reduction can be achieved.

FIG. 1 is a diagram illustrating an example of a configuration of an LED power supply device 100 according to the first embodiment. FIG. 2 is a waveform diagram showing an example of operation waveforms for switching between LED lighting and LED extinguishing of the LED power supply device 100 shown in FIG. FIG. 3 is a diagram illustrating an example of the configuration of a conventional LED power supply device 100A.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

First embodiment

FIG. 1 is a diagram illustrating an example of the configuration of the LED power supply device 100 according to the first embodiment.

As shown in FIG. 1, the LED power supply device 100 according to the embodiment includes, for example, a primary circuit FC1, an LED lamp X, a first LED terminal TX1, a second LED terminal TX2, and a first LED Secondary coil L2a, second secondary coil L2b, first rectifying / smoothing circuit A1, second rectifying / smoothing circuit A2, current detecting means RX, feedback means YA, and amplifier capacitor C And a control resistor R and a control circuit (semiconductor integrated circuit) CON.

The first LED terminal TX1 is connected to the anode side of the LED lamp X including one or a plurality of LED elements XA connected in series.

The second LED terminal TX2 is connected to the cathode side of the LED lamp X.

The first secondary coil L2a constitutes a transformer Z together with the primary coil L1 and the second secondary coil L2b.

The LED lamp X includes one or a plurality of LED elements XA connected in series.

The primary side circuit FC1 includes a primary side coil L1 and an AC power source S. The primary side circuit FC1 outputs an AC voltage generated from the AC power source S to the primary side coil L1 in response to the feedback signal FBS.

More specifically, as shown in FIG. 1, the primary circuit FC1 includes a passive element YB that receives the feedback signal FBS and outputs a reception signal corresponding to the received feedback signal FBS. The primary circuit FC1 outputs an alternating voltage to the primary coil L1 in accordance with the received signal. The passive element YB is, for example, a photodiode or a phototransistor.

For example, when the feedback signal FBS indicates the lighting of the LED lamp X, the primary side circuit FC1 applies an AC voltage to the primary side coil in accordance with the feedback signal FBS so that a constant current that can be turned on flows through the LED lamp X. It outputs to L1.

In other words, when the dimming signal AS indicates the lighting of the LED lamp X, the primary side circuit FC1 provides the feedback signal FBS with a current of the LED lamp X corresponding to the dimming rate specified by the dimming signal AS. Accordingly, an AC voltage is output to the primary coil L1.

On the other hand, when the feedback signal FBS indicates that the LED lamp X is extinguished, the primary side circuit FC1 supplies the AC voltage to the primary side so that the LED lamp X is extinguished and drivable power is supplied to the control circuit CON. It outputs to the coil L1.

In other words, when the dimming signal AS indicates that the LED lamp X is extinguished, the primary side circuit FC1 outputs the feedback signal FBS so that the LED lamp X is extinguished and drivable power is supplied to the control circuit CON. Accordingly, an AC voltage is output to the primary coil L1.

More specifically, when the dimming signal AS indicates that the LED lamp X is extinguished, the primary side circuit FC1 integrates the forward voltage of the LED element XA and the number of stages of the LED element XA of the LED lamp X. The AC voltage output to the primary coil L1 is controlled in accordance with the feedback signal FBS so as to be less than the value.

The first rectifying / smoothing circuit A1 is connected to the first secondary coil L2a and the first rectifying / smoothing circuit A1, for example, as shown in FIG. The first rectifying / smoothing circuit A1 rectifies the induced voltage of the first secondary coil L2a and supplies it to the LED lamp X via the first and second LED terminals TX1, TX2. ing.

The first rectifying / smoothing circuit A1 includes, for example, a first rectifying element (diode) D1, a first output capacitor C1, and a current detecting means RX as shown in FIG.

For example, as shown in FIG. 1, the first rectifying element D1 has one end (anode) connected to the other end of the first secondary coil L2a and the other end (cathode) connected to the first LED terminal TX1. The diode is connected and has a forward direction from the other end of the first secondary coil L2a toward the first LED terminal TX1.

The first output capacitor C1 has one end connected to the first LED terminal TX1 and the other end connected to the second LED terminal TX2.

As described above, the second secondary coil L2b constitutes the transformer Z together with the primary coil L1 and the first secondary coil L2a.

The second secondary coil L2b is set so that the induced electromotive force is smaller than the induced electromotive force of the first secondary coil L2a. For example, the number of turns of the second secondary coil L2b is set to be smaller than the number of turns of the first secondary coil L2a.

Note that the number of turns of the second secondary coil L2b is set to be smaller than the number of turns of the first secondary coil L2a.

Further, as shown in FIG. 1, for example, the current detection means RX is a current detection resistor having one end connected to the second LED terminal TX2 and the other end connected to one end of the first secondary coil L2a. is there. In the example shown in FIG. 1, it is provided in the first rectifying / smoothing circuit A1. However, the current detection means RX may be provided between the output of the first rectifying / smoothing circuit A1 and the LED lamp X.

The current detection means RX outputs a detection signal SRX corresponding to the current flowing through one end.

The second rectifying / smoothing circuit A2 is connected to the second secondary coil L2b. The second rectifying / smoothing circuit A2 supplies an output voltage VC obtained by rectifying the induced voltage of the second secondary coil L2b to the control circuit CON via the power supply terminal TS.

The second rectifying / smoothing circuit A2 includes, for example, a second rectifying element D2 and a second output capacitor C2, as shown in FIG.

For example, as shown in FIG. 1, the second rectifying element D2 has one end (anode) connected to the other end of the second secondary coil L2b and the other end (cathode) connected to the power supply terminal TS. The diode is such that the direction from the other end of the second secondary coil L2b toward the power supply terminal TS is the forward direction.

Further, for example, as shown in FIG. 1, the second output capacitor C2 has one end connected to the power supply terminal TS and the other end grounded (connected to the ground terminal TGND).

Further, the feedback means YA is connected to the output of the second rectifying / smoothing circuit A2.

More specifically, the feedback means YA is connected between the power supply terminal VC (output of the second rectifying / smoothing circuit A2) and the signal terminal TOUT, for example, as shown in FIG. The feedback means YA outputs a feedback signal FBS to the primary side circuit FC1 based on the flowing current.

That is, the feedback means YA is based on the detection signal SRX of the current detection means RX and the output voltage VC of the second rectifying / smoothing circuit A2 (as described later, the control circuit CON outputs via the signal terminal TOUT. Based on the control signal, the feedback signal FBS is output to the primary circuit FC1.

This feedback means YA is an insulating signal transmission element that insulates and transmits the feedback signal FBS based on the detection signal SRX of the current detection means RX and the output voltage VC of the second rectifying and smoothing circuit A2. More specifically, as shown in FIG. 1, for example, the feedback means YA has an anode connected to the power supply terminal TS and a cathode connected to the signal terminal TOUT (one end of the current detection means RX via an amplifier capacitor C described later). To) the connected light emitting diode.

The cathode of this light emitting diode corresponds to the control terminal TYA. By supplying the control signal SC to the control terminal TYA, the current flowing through the light emitting diode changes. That is, as described later, the control circuit CON supplies a control signal to the control terminal TYA, whereby the feedback signal FBS is controlled.

The amplifier capacitor C is connected between the control terminal TYA (signal terminal TOUT) and the inverting input terminal (signal terminal TOP) of the operational amplifier OPA.

The control resistor R is connected between the power supply terminal TS (the output of the second rectifying and smoothing circuit A2) and the feedback means YA (the anode of the light emitting diode).

Further, the control circuit CON is driven by the power (output voltage VC) supplied from the second rectifying / smoothing circuit A2 via the power supply terminal TS.

The control circuit CON is supplied with a dimming signal AS that regulates the dimming rate of the LED lamp X output from an external dimming means (not shown) via the input terminal TIN, and is detected by the current detection means RX. The signal SRX is supplied via the signal terminal TOP, and the output voltage (power supply voltage) VC of the second rectifying / smoothing circuit A2 is supplied via the power supply terminal TS.

The control circuit CON supplies a control signal SC for controlling the feedback signal FBS to the control terminal TYA of the feedback means YA via the signal terminal TOUT according to the dimming signal AS, the detection signal SRX, and the output voltage VC. It is designed to output.

For example, when the dimming signal AS indicates the lighting of the LED lamp X, the control circuit CON feeds back the control signal so that the current of the LED lamp X corresponds to the dimming rate specified by the dimming signal AS. Output to the control terminal (cathode) TYA of YA.

Then, the feedback means YA outputs a feedback signal FBS indicating the lighting of the LED lamp X to the primary side circuit FC1.

Thereby, when the dimming signal AS indicates the lighting of the LED lamp X, a constant current is applied to the LED lamp X via the first secondary coil L2a so that the LED lamp X is lit from the primary circuit FC1. In addition to being supplied, a driving power supply voltage is supplied to the control circuit CON via the second secondary coil L2b.

On the other hand, when the dimming signal AS indicates that the LED lamp X is extinguished, the control circuit CON determines that the output voltage VC of the second rectifying and smoothing circuit A2 is when the dimming signal AS indicates that the LED lamp X is on. A control signal is output to the feedback means YA so as to be a preset voltage lower than the output voltage output from the second rectifying / smoothing circuit A2. *

More specifically, when the dimming signal AS indicates that the LED lamp X is extinguished, the control circuit CON determines that the output voltage of the second rectifying / smoothing circuit A2 indicates that the dimming signal AS is lit on the LED lamp X. Control so that the first voltage Vth1 lower than the output voltage output from the second rectifying and smoothing circuit A2 is the upper limit and the second voltage Vth2 lower than the first voltage Vth1 is the lower limit. The signal is output to the control terminal TYA of the feedback means YA.

The feedback means YA outputs a feedback signal FBS indicating that the LED lamp X is turned off.

As described above, the primary circuit FC1 integrates the forward voltage of the LED element XA and the number of stages of the LED element XA of the LED lamp X in accordance with the feedback signal FBS indicating that the LED lamp X is turned off. The AC voltage output to the primary coil L1 is controlled so as to be less than the voltage (turns off the light).

Further, when the LED lamp X is turned off, the output voltage VC of the second rectifying and smoothing circuit A2 is the output voltage VC output from the second rectifying and smoothing circuit A2 when the dimming signal AS indicates the lighting of the LED lamp X. The first voltage Vth1 lower than the first voltage Vth1 is set as the upper limit value, and the second voltage Vth2 lower than the first voltage Vth1 is set as the lower limit value (voltage ripple control).

Therefore, when the LED lamp X is turned off, the output voltage VC controlled between the first voltage Vth1 and the second voltage Vth2 is supplied to the control circuit CON. That is, when the dimming signal AS indicates that the LED lamp X is extinguished, the primary side circuit FC1 supplies the control circuit CON with power that can be driven and the LED lamp X is extinguished.

Thus, an auxiliary power supply for supplying power to the control circuit CON that controls the lighting of the LED lamp X becomes unnecessary.

Here, as shown in FIG. 1, for example, the control circuit CON includes a dimming circuit AC, an operational amplifier OPA, a comparator COMP, a voltage dividing circuit RD, a switching circuit SW, and an internal power supply SX.

The dimming circuit AC outputs a DC voltage corresponding to the dimming rate defined by the dimming signal AS.

In the operational amplifier OPA, a DC voltage is input to the non-inverting input terminal, the inverting input terminal is connected to one end of the current detection means RX, and the detection signal SRX is input. The operational amplifier OPA outputs a control signal to the control terminal TYA via the switching circuit SW and the signal terminal TOUT so that the DC voltage VA is equal to the average value of the detection signal SRX.

The voltage dividing circuit RD outputs a divided voltage VD obtained by dividing the output voltage (power supply voltage) VC output from the second rectifying and smoothing circuit A2. For example, as shown in FIG. 1, the voltage dividing circuit RD has one end connected to the power supply terminal TS, the other end grounded (connected to the ground terminal TGND), and a divided voltage obtained by dividing the output voltage VC. It is designed to output.

For example, as shown in FIG. 1, the voltage dividing circuit RD includes a first voltage dividing resistor RD1 having one end connected to the output of the second rectifying / smoothing circuit A2 through a power supply terminal TS, and one end having a first end. And a second voltage dividing resistor RD2 connected to the other end of the voltage dividing resistor RD1 and having the other end connected to the ground terminal TGND.

The voltage dividing resistor RD outputs a voltage between the other end of the first voltage dividing resistor RD1 and one end of the second voltage dividing resistor RD2 as a divided voltage VD.

The comparator COMP receives a divided voltage VD at its inverting input terminal and a preset reference voltage VB at its non-inverting input terminal, and controls the control signal based on the result of comparing the divided voltage VD and the reference voltage VB ( Voltage). This comparator COMP has a hysteresis characteristic.

For example, as shown in FIG. 1, the reference voltage VB is output from the reference power supply B.

The switching circuit SW also includes a first state in which the output of the operational amplifier and the control terminal TYA (signal terminal TOUT) of the feedback means YA are conducted when the dimming signal AS indicates the lighting of the LED lamp X, and the dimming When the signal AS indicates that the LED lamp X is extinguished, the second state in which the output of the comparator and the control terminal TYA (signal terminal TOUT) of the feedback means YA are conducted is switched.

Note that the dimming circuit AC controls the operation of the switching circuit SW (switching between the first state and the second state) in accordance with the dimming signal AS.

That is, the control circuit CON outputs the control signal output from the operational amplifier OPA to the control terminal TYA in the first state of the switching circuit SW described above.

Thus, when the dimming signal AS indicates the lighting of the LED lamp X, the control circuit CON outputs the control signal output from the operational amplifier OPA to the control terminal TYA of the feedback means YA via the signal terminal TOUT. .

That is, the control circuit CON outputs the control signal SC to the control terminal (cathode) TYA of the feedback means YA so that the current of the LED lamp X corresponds to the dimming rate specified by the dimming signal AS.

On the other hand, the control circuit CON outputs the voltage output from the comparator COPM to the control terminal TYA in the second state of the switching circuit SW described above.

Thus, when the dimming signal AS indicates that the LED lamp X is extinguished, the control circuit CON outputs the voltage output by the comparator COMP to the control terminal TYA of the feedback means YA.

That is, the control circuit CON becomes less than the voltage obtained by integrating the forward voltage of the LED element XA and the number of stages of the LED element XA of the LED lamp X (turns off), and the output voltage VC supplied to the control circuit CON is the first voltage The control signal SC is output to the control terminal (cathode) TYA of the feedback means YA so that the first voltage Vth1 becomes the upper limit value and the second voltage Vth2 becomes the lower limit value.

Note that the internal power supply SX supplies a voltage based on the output voltage VC supplied to the power supply terminal TS to each component of the control circuit CON.

Next, an example of the operation of the LED power supply apparatus 100 having the above configuration will be described with reference to FIG.

FIG. 2 is a waveform diagram showing an example of operation waveforms for switching between turning on and off the LED power supply device 100 shown in FIG.

As shown in FIG. 2, for example, when the mode is LED lighting (dimming), the control circuit CON responds to the on-duty of the dimming signal AS (DC voltage VA output from the dimming circuit AC). The switching circuit SW is set to the first state, and the control signal output from the operational amplifier OPA is output to the control terminal TYA.

The primary side circuit FC1 outputs an AC voltage to the primary side coil L1 so that a constant current that can be lit on the LED lamp X flows according to the feedback signal FBS.

Thereby, the current ILED of the LED lamp X flows according to the on-duty of the dimming signal AS, that is, the dimming rate specified by the dimming signal AS. Thereby, the LED voltage VLED of the LED lamp X corresponding to the dimming rate specified by the dimming signal AS is obtained.

At this time, the output voltage VC output from the second rectifying / smoothing circuit A2 changes so as to correlate with the LED voltage VLED.

On the other hand, when the mode is LED off, the ON duty of the dimming signal AS becomes zero, the control circuit CON sets the switching circuit SW to the second state, and the control signal output from the comparator COMP is the control terminal. Output to TYA.

Then, the primary side circuit FC1 is less than a voltage obtained by integrating the forward voltage of the LED element XA and the number of stages of the LED element XA of the LED lamp X in accordance with the feedback signal FBS indicating that the LED lamp X is turned off. The AC voltage output to the primary side coil L1 is controlled (to turn off the light).

By the operation as described above, the LED power supply device 100 does not require an auxiliary power supply for supplying power to the control circuit CON that controls the lighting of the LED lamp X.

As described above, in the LED power supply device according to one aspect of the present invention, the primary side circuit FC1 that includes the primary side coil L1 and outputs an AC voltage to the primary side coil L1 according to the feedback signal FBS, and the primary side A first secondary coil L2a constituting the coil L1 and the transformer Z; a second secondary coil L2b whose induced electromotive force is smaller than the induced electromotive force of the first secondary coil L2a; A first rectifying / smoothing circuit A1 connected to the secondary coil L2a, and an LED lamp X including a plurality of LED elements XA connected to the first rectifying / smoothing circuit A1 and connected in series, The second rectifying / smoothing connected to the current detection means RX included in the first rectifying / smoothing circuit A1 or between the first rectifying / smoothing circuit A1 and the LED lamp X and the second secondary coil L2b. Circuit A2 and second Feedback means YA connected to the rectifying / smoothing circuit A2 and outputting the feedback signal FBS to the primary circuit FC1 based on the detection signal of the current detecting means RX and the output voltage of the second rectifying / smoothing circuit A2, and a second Driven by the electric power supplied from the rectifying / smoothing circuit A2, and according to the dimming signal AS that regulates the dimming rate of the LED lamp X, the detection signal of the current detecting means RX, and the output voltage of the second rectifying / smoothing circuit A2. And a control circuit CON that outputs a signal to the feedback means YA.

In particular, when the dimming signal AS indicates the lighting of the LED lamp X, the control circuit CON feeds back the control signal so that the current of the LED lamp X corresponds to the dimming rate specified by the dimming signal AS. When the dimming signal AS indicates that the LED lamp X is extinguished, the control signal is output so that the output voltage of the second rectifying and smoothing circuit A2 becomes a preset voltage. Output to the control terminal TYA of the feedback means YA (ripple control).

Thereby, when the dimming signal AS indicates the lighting of the LED lamp X, a constant current is applied to the LED lamp X via the first secondary coil L2a so that the LED lamp X is lit from the primary circuit FC1. In addition to being supplied, a power supply voltage for driving is supplied to the control circuit CON via the second secondary coil L2b.

On the other hand, when the dimming signal AS indicates that the LED lamp X is extinguished, the primary circuit FC1 extinguishes the LED lamp X and supplies drivable power to the control circuit CON.

Thus, the LED power supply device according to one aspect of the present invention reduces the auxiliary power supply for supplying power to the control circuit CON that controls the lighting of the LED lamp X, thereby reducing the size and manufacturing of the device. Cost can be reduced.

Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and the equivalents thereof. *

100 LED power supply device FC1 primary side circuit X LED lamp TX1 first LED terminal TX2 second LED terminal L2a first secondary coil L2b second secondary coil A1 first rectifying and smoothing circuit A2 second Rectifying and smoothing circuit RX Current detecting means YA Feedback means C Capacitor for amplifier R Control resistor CON Control circuit (semiconductor integrated circuit)
AC dimmer circuit OPA operational amplifier COMP comparator RD voltage divider circuit SW switching circuit SX internal power supply

Claims

A primary circuit having a primary coil and outputting an alternating voltage to the primary coil in response to a feedback signal;
A first secondary coil that forms a transformer with the primary coil;
A second secondary coil that constitutes the transformer together with the primary coil and the first secondary coil;
A first rectifying and smoothing circuit connected to the first secondary coil;
An LED lamp connected to the first rectifying and smoothing circuit and including one or a plurality of LED elements connected in series;
Current detection means provided in the first rectifying / smoothing circuit or between the first rectifying / smoothing circuit and the LED lamp;
A second rectifying and smoothing circuit connected to the second secondary coil;
Feedback means connected to the second rectifying and smoothing circuit and outputting the feedback signal to the primary circuit based on a detection signal of the current detecting means and an output voltage of the second rectifying and smoothing circuit;
A dimming signal that is driven by power supplied from the second rectifying and smoothing circuit and that regulates the dimming rate of the LED lamp output from an external dimming unit, a detection signal of the current detection unit, and the first A control circuit for outputting a control signal for controlling the feedback signal to a control terminal of the feedback means according to an output voltage of the rectifying and smoothing circuit of 2,
The control circuit includes:
When the dimming signal indicates lighting of the LED lamp, a control signal is output to the control terminal of the feedback means so that the current of the LED lamp corresponds to the dimming rate specified by the dimming signal,
On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the output voltage of the second rectifying and smoothing circuit is output from the second rectifying and smoothing circuit when the dimming signal indicates that the LED lamp is on. The LED power supply apparatus, wherein the control signal is output to a control terminal of the feedback means so as to be a preset voltage lower than the output voltage.
The control circuit includes:
When the dimming signal indicates the lighting of the LED lamp, a control signal is output to the control terminal of the feedback means so that the LED lamp current corresponds to the dimming rate specified by the dimming signal,
On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the output voltage of the second rectifying and smoothing circuit is output from the second rectifying and smoothing circuit when the dimming signal indicates that the LED lamp is on. A control signal is output to the control terminal of the feedback means so that a first voltage lower than the output voltage is an upper limit value and a second voltage lower than the first voltage is a lower limit value. The LED power supply device according to claim 1.
The primary circuit is
When the dimming signal indicates lighting of the LED lamp, the AC voltage is output to the primary coil according to the feedback signal so that the LED lamp current corresponds to the dimming rate specified by the dimming signal. And
On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the AC voltage is applied to the primary voltage according to the feedback signal so that the LED lamp is extinguished and drivable power is supplied to the control circuit. It outputs to a side coil. The LED power supply device of Claim 1 characterized by the above-mentioned.
The control circuit includes:
A dimming circuit that outputs a DC voltage corresponding to a dimming rate specified by the dimming signal;
The DC voltage is input to a non-inverting input terminal, the inverting input terminal is connected to the current detection means, and an operational amplifier that outputs a control signal so that the DC voltage and the detection signal are equal,
A voltage dividing circuit that outputs a divided voltage obtained by dividing the output voltage of the second rectifying and smoothing circuit;
The divided voltage is input to the inverting input terminal, a preset reference voltage is input to the non-inverting input terminal, a control signal is output based on the result of comparing the divided voltage and the reference voltage, and hysteresis characteristics A comparator having
The control circuit includes:
When the dimming signal indicates the lighting of the LED lamp, the control signal output by the operational amplifier is output to the control terminal of the feedback means,
The LED power supply device according to claim 1, wherein when the dimming signal indicates that the LED lamp is turned off, the control signal output by the comparator is output to a control terminal of the feedback means.
The control circuit includes:
A first state in which the output of the operational amplifier and the control terminal of the feedback means are conducted when the dimming signal indicates lighting of the LED lamp; and A switching circuit for switching between a second state of conducting the output of the comparator and the control terminal of the feedback means;
The LED power supply device according to claim 4, wherein the dimming circuit controls an operation of the switching circuit.
The primary circuit is
When the dimming signal indicates that the LED lamp is extinguished, the primary side according to the feedback signal so as to be less than the voltage obtained by integrating the forward voltage of the LED element and the number of stages of the LED element of the LED lamp. The AC voltage output to the coil is controlled. The LED power supply device according to claim 3.
The LED power supply device according to claim 2, wherein the number of turns of the second secondary coil is smaller than the number of turns of the first secondary coil.
The power supply device for LED according to claim 2, wherein the feedback means is an insulated signal transmission element that insulates and transmits the feedback signal based on the detected current.
The LED power supply apparatus according to claim 8, wherein the feedback means is a light emitting diode.
The primary side circuit includes a passive element that receives the feedback signal and outputs a reception signal corresponding to the received feedback signal.
10. The LED power supply device according to claim 9, wherein the primary circuit outputs an AC voltage to the primary coil in accordance with the received signal.
The LED power supply device according to claim 10, wherein the passive element is a photodiode or a phototransistor.
The first rectifying / smoothing circuit includes:
One end is connected to the other end of the first secondary coil, the other end is connected to the first LED terminal, and the other end of the first secondary coil is directed to the first LED terminal. A first rectifying element whose direction is a forward direction;
A first output capacitor having one end connected to the first LED terminal and the other end connected to the second LED terminal;
One end connected to the second LED terminal and the other end connected to one end of the first secondary coil, a current detection resistor as the current detection means,
The second rectifying / smoothing circuit includes:
One end is connected to the other end of the second secondary coil, the other end is connected to the power supply terminal, and the direction from the other end of the second secondary coil toward the power supply terminal is the forward direction. Two rectifying elements;
The LED power supply device according to claim 1, further comprising: a second output capacitor having one end connected to the power supply terminal and the other end grounded.
A primary side circuit that has a primary side coil and outputs an AC voltage to the primary side coil in response to a feedback signal; a first secondary side coil that constitutes a transformer with the primary side coil; and the primary side coil; A second secondary coil constituting the transformer together with the first secondary coil; a first rectifying / smoothing circuit connected to the first secondary coil; and the first rectifying / smoothing circuit. LED lamps including one or a plurality of LED elements connected in series, and provided in the first rectifying / smoothing circuit or between the first rectifying / smoothing circuit and the LED lamp. Connected to the second rectifying / smoothing circuit connected to the second secondary coil, the second rectifying / smoothing circuit connected to the second rectifying / smoothing circuit, the detection signal of the current detecting means, and the second Based on the output voltage of the rectifying and smoothing circuit A semiconductor integrated circuit applied the serial feedback signal to the LED power supply device and a feedback means for outputting to the primary circuit,
The semiconductor integrated circuit is:
A dimming signal that is driven by power supplied from the second rectifying and smoothing circuit and that regulates the dimming rate of the LED lamp output from an external dimming unit, a detection signal of the current detection unit, and the first A control signal for controlling the feedback signal is output to a control terminal of the feedback means in accordance with an output voltage of the rectifying and smoothing circuit 2;
When the dimming signal indicates lighting of the LED lamp, a control signal is output to the control terminal of the feedback means so that the current of the LED lamp corresponds to the dimming rate specified by the dimming signal,
On the other hand, when the dimming signal indicates that the LED lamp is extinguished, the output voltage of the second rectifying and smoothing circuit is output from the second rectifying and smoothing circuit when the dimming signal indicates that the LED lamp is on. The semiconductor integrated circuit, wherein the control signal is output to a control terminal of the feedback means so as to be a preset voltage lower than the output voltage.