JP2018181454A - Driver with dc luminous load and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for micro dimming and unlighting in a driver for driving a DC luminous load and a lighting device, constituted of a step-down converter including a control circuit (integrated circuit) on the high side.SOLUTION: A driver 2 has an integrated circuit Z1 constituted of a step-down converter where a switching element Q1, a reactor L1 and a smoothing capacitor C6 are connected in series with a DC power supply E, and a regenerative diode D1 is connected in parallel with the series circuit of the reactor L1 and the smoothing capacitor C6, and performing ON/OFF control of the switching element Q1 having a reference potential at the junction of the switching element Q1 and the reactor L1, and a bypass circuit 3 connected in parallel with a DC luminous load 4. The integrated circuit Z1 has current detection means for detecting the current flowing to the DC luminous load 4, and a current control means for controlling the current flowing to the DC luminous load in response to an external dimming signal, and the bypass circuit 3 performs ON/OFF operation according to the dimming signal.SELECTED DRAWING: Figure 1

Description

The present invention relates to a drive device and a lighting device that perform light control on a DC light emission load.

The electrical energy used for lighting in major technologically advanced countries is said to reach about 15% of the total power generation in each country, and there is a need to reduce the electrical energy from the viewpoint of global environmental issues. With such requirements in mind, LEDs (Light Emitting) are used as light sources that consume less power and have a longer life than incandescent bulbs and fluorescent lamps used in conventional lighting devices.
A lighting apparatus provided with a light emitting load such as a direct current light emitting device such as a diode) or an organic EL (Electro-Luminescence) has attracted attention.

Furthermore, in recent years, as described in Patent Document 1, for the purpose of contributing to improvement of production efficiency in a home or an office, development of a room lighting device capable of dimming is being promoted.
Dimming is to change the brightness of the illumination based on information from inside and outside the illumination device.

As a switching power supply of a conventional lighting apparatus, as shown in FIG. 4, a switching power supply comprising a switching power supply comprising a step-down converter and a light emitting diode (LED) connected in parallel to the output terminal of the switching power supply is known. (Patent Document 1). In the conventional lighting device, since the switching element of the step-down converter is a high-side switching element in the circuit, a driving voltage based on the potential side higher than the ground level is driven from the input voltage to the constant voltage power source. Generate through. Further, the control circuit is connected to the ground level, and a control signal is transmitted from the control circuit via the level shift circuit to turn on / off the high side switch element. Here, the control circuit power supply Vcc is supplied from another power supply, and is also used for the drive voltage on the high side from the control circuit power supply Vcc via the bootstrap diode.

Patent No. 5825433

However, the switching power supply device of Patent Document 1 is not considered on the premise of dimming. For this reason, when dimming control by an external signal is performed, in particular, dimming to turn off, the circuit current of the constant voltage power supply connected to the input voltage and the drive circuit of the switching element flows to the light emitting diode (LED). , There is a problem that can not completely turn off.

The present invention provides a drive device and a lighting device capable of dimming light to a light emitting load with respect to a direct current light emitting load.

According to one aspect of the present invention, a DC power supply, a DC light emission load, and a drive device for converting energy obtained from the DC power supply and outputting the energy to the DC light emission load, wherein the DC power supply includes a switching element, a reactor, and smoothing. A step-down type converter in which a capacitor is connected in series, a regenerative diode is connected in parallel to a series circuit of the reactor and the smoothing capacitor, and a DC voltage stepped down by controlling the switching element ON / OFF is supplied to the DC light emission load And a control circuit that turns on / off the switching element with a connection point between the switching element and the reactor as a reference potential, and a bypass circuit connected in parallel to the DC light emitting load, the control The circuit includes current detection means for detecting the current flowing to the DC light emission load, and a dimming signal from the outside And current control means for controlling the current flowing to the direct current light emitting load, and the bypass circuit bypasses the current flowing to the direct current light emitting load when the dimming signal is at a minute dimming or extinguishing level. It is characterized by

According to the present invention, it is possible to provide a drive device and a lighting device capable of extinguishing and minute dimming with respect to a DC light emitting load.

It is a circuit diagram showing composition of lighting installation 1 concerning an embodiment of the present invention. The integrated circuit block diagram of the drive device 2 which concerns on embodiment of this invention is shown. Fig. 6 shows a graph of dimming signal voltage-dimming current according to an embodiment of the present invention. It is a circuit diagram which shows the structure of the illuminating device described in patent document 1. FIG.

Next, embodiments of the present invention will be described with reference to the drawings.
The embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention specify the structure, arrangement, and the like of components as described below. It is not something to do. Various modifications can be made to the embodiments of the present invention within the scope of the claims.

(Embodiment)
FIG. 1 is a circuit diagram showing a configuration of a lighting device 1 according to an embodiment of the present invention. The lighting device 1 according to the present embodiment is constituted by a drive device 2 connected to an external direct current power source E, and the drive device 2 is a direct current light emission consisting of direct current light emitting devices LED1 to LEDn according to an external light control signal. Power is supplied to the load 4.
Further, the driving device 2 includes a first terminal T1 and a second terminal T2 connected to the DC power supply E2.
Third terminal T3 connected to DC light emitting load 4 consisting of DC light emitting devices LED1 to LEDn
And a fourth terminal T4 and a fifth terminal T5 and a sixth terminal T6 for receiving the dimming signal.

The driving device 2 constitutes a step-down chopper circuit, and constitutes a bypass circuit 2 connected in parallel to the switching element Q1, the current detection resistor R1, the reactor L1, the smoothing capacitor C6 and the regenerative diode D1 and the smoothing capacitor C6. Resistors R6 to R10 and MOS
It comprises an integrated circuit Z1 which is a control circuit which turns on / off the switching element Q1 based on the FET Q2 and Q3, the photocoupler PC1, and a light control signal from the outside, and peripheral circuits thereof.

The driving device 2 according to the present embodiment turns on the switching element Q1 from the DC power supply E,
A series circuit of a current detection resistor R1, a reactor L1, and a smoothing capacitor C1.
And charge the smoothing capacitor C6 and at the same time direct light emitting devices LED1 to L
Power is supplied to the DC light emitting load 4 consisting of EDn. Next, the switching element Q1 is turned off, and the energy stored in the reactor L1 is charged to the smoothing capacitor C6 through the current detection resistor R1, the reactor L1 and the smoothing capacitor C1 via the regenerative diode D1 and the DC light emitting devices LED1 to LED1. Power is supplied to a direct current light emitting load 4 composed of LEDn.

The integrated circuit Z1 and its peripheral circuits for on / off controlling the switching element Q1 based on the light adjustment signal from the outside are composed of the integrated circuit Z1, resistors R2 to R5, capacitors C1 to C5, and a diode D2.
FIG. 2 shows an internal block diagram of the integrated circuit Z1. Integrated circuit Z1 is a start circuit STARTU
P, internal power supply Reg, oscillator OSC, flip flop FF1, logic circuit AND1, OR
1, NOR1, drive circuit DRV, error amplifier OTA, feedback control unit Feedba
ck control, bottom detection unit Bottom detection, overcurrent protection O
It consists of CP, over voltage protection OVP etc.

The integrated circuit Z1 inputs the trigger pulse from the oscillator OSC to the set terminal of the flip flop FF1, and outputs it to the gate of the switching element Q1 through the logic circuit AND1 and the drive circuit DRV to turn it on. The on operation of the switching element Q1 causes a voltage drop in the current detection resistor R1, and the voltage drop is transmitted to the integrated circuit Z through the filter of the resistor R4 and the capacitor C4.
Input to the Isense terminal of 1. An error amplifier OTA is connected to the Isense terminal.
The error amplifier OTA outputs the signal to the COMP terminal connected with the capacitor C2 and the feedback control unit Feedback control. Feedback controller Feedb
ack control compares the COMP terminal voltage with the Vref terminal voltage described later,
When the voltage at the COMP terminal becomes higher, the flip flop F via the logic circuit OR1
Output H level to the reset terminal of F1. Thereby, the switching element Q1 is turned off.
Here, an external dimming signal is input to the Vref terminal through a parallel circuit of a resistor R5 and a capacitor C5. That is, the dimming signal voltage is input to the Vref terminal.
Also, the voltage drop of the current detection resistor R1 is a filter consisting of a resistor R3 and a capacitor C3
Are input to the OCP terminal of the integrated circuit Z1. Overcurrent protection OCP at the OCP terminal
And the bottom detection unit Bottom Detection is connected. Current detection resistor R
When the voltage drop of 1 exceeds the predetermined threshold value, a signal is output from the overcurrent protection OCP to the logic circuit OR1, and the switching element Q1 is turned off.
Further, when the voltage drop of the current detection resistor R1 becomes approximately zero or more, a signal is input from the bottom detection unit Bottom Detection to the oscillator OSC, and the oscillator OSC is generated.
Trigger pulse is output to turn on the switching element Q1. That is,
The bottom detection unit Bottom Detection detects that the regenerative current of the reactor L1 has ended, and turns on the switching element Q1.
Next, the diode D2 is connected to the capacitor C1 and the power supply terminal Vcc of the integrated circuit Z1,
The voltage of the divided winding of the reactor L1 is rectified to obtain the power supply terminal Vcc. The voltage of the split winding of the reactor L1 is a voltage proportional to the voltage ratio of the DC light emitting load 4 to the divided turns ratio of the reactor L1.
Further, the overvoltage protection OVP is connected to the power supply terminal Vcc, and when the voltage of the divided winding of the reactor L1 exceeds the rated voltage of the integrated circuit Z1, the on / off operation of the switching element Q1 is stopped.

As shown in FIG. 1, the drive device 2 according to the present embodiment turns ON / O the switching element Q1.
The GND of the integrated circuit Z1 to be FF-controlled is connected to the source of the switching element Q1 and the cathode of the regenerative diode. That is, it has a floating configuration connected to the high side of the step-down converter.

Here, at power-on, the integrated circuit Z1 supplies a starting current from the voltage from the DC power supply E via the reactor L1 and the DC light emitting load 4 including the DC light emitting devices LED1 to LEDn. The capacitor C1 connected to the power supply terminal Vcc of the integrated circuit Z1 due to the flow of the starting current
Starts after it is charged. The power supply of the integrated circuit Z1 after start-up rectifies and smoothes the divided winding voltage of the reactor L1 via the diode 2 as described above, thereby stopping the start-up current from the DC power supply E.
After startup, feedback control of ON / OFF of the switching element Q1 is performed so that a current corresponding to an external dimming signal voltage input to the Vref terminal of the integrated circuit Z1 flows to the resistor R1. That is, as shown in FIG. 1, since the resistor R1 and the DC light emission load 4 are connected in series, a current corresponding to the light adjustment signal voltage flows to the DC light emission load 4, and a DC light emission load corresponding to the light adjustment signal Do 4 dimming.

The bypass circuit 3 according to the present embodiment shown in FIG. 1 corresponds to the fine light adjustment and extinguishing means of the present invention.
The resistors R6 and R7, the MOSFET Q2 and the photocoupler PC1-1 that constitute the bypass circuit 3 are connected to the power supply terminal Vcc of the integrated circuit Z1 which is at the potential high side. Specifically, a series circuit of the photodiode PC1-1, the resistor R8, and the MOSFET Q2 of the photocoupler PC1 is connected between the power supply terminal Vcc and the GND terminal of the integrated circuit Z1. In addition, the Vref terminal of the integrated circuit Z1, that is, the resistor R5, the MOSF at both ends of the capacitor C5
The gate source of ETQ2 and resistor R6 are connected.
The resistors R8 to R10, the MOSFET Q3, and the phototransistor PC1-2 of the photocoupler PC1 are connected between the terminals of the smoothing capacitor C6. Specifically, a series circuit of resistors R8 and R9 and a series circuit of resistors R10 and MOSFET Q3 are connected in parallel between both terminals of the smoothing capacitor C6. With the gate and source of MOSFET Q3 across resistor R9,
The photocouplers PC1-2 are connected in parallel.

When the dimming signal voltage is equal to or higher than the threshold voltage of the gate of the MOSFET Q2 of the bypass circuit 3,
The photodiode PC1-1 of the photocoupler PC1 is turned on, and the phototransistor PC1-2 of the photocoupler PC1 that is at the potential low side is turned on, and the MOSFET Q is turned on.
Turn 3 off. As a result, the bypass circuit 3 is turned off and is not discharged via the resistor R10.
When the dimming signal voltage becomes zero or less than the threshold voltage of the gate of the MOSFET Q2 of the bypass circuit 3, the integrated circuit Z1 stops the switching operation of the switching element Q1.
As a result, although the integrated circuit Z1 can not obtain the power supply voltage Vcc from the divided winding of the reactor L1, it starts the start circuit STARTUP and supplies the power supply voltage Vcc from the DC power supply. Here, by supplying the power supply voltage Vcc from the DC power supply, the circuit current of the integrated circuit Z1 flows in the DC light emission load 4.
However, MOSF of bypass circuit 3 which discharges the circuit current of integrated circuit Z1 at the same time as the dimming signal voltage becomes zero or less than the threshold voltage of the gate of MOSFET Q2 of bypass circuit 3
The ETQ 3 is turned on to bypass the circuit current flowing to the DC light emitting load 4. By this,
It enables minute dimming or extinguishing of the DC light emission load 4.

FIG. 3 shows a graph of dimming signal voltage-dimming current according to the embodiment of the present invention.
When the dimming signal voltage becomes lower than a predetermined value (10% or lower in FIG. 3), the switching element Q1 is turned off, the circuit current (approximately 2 mA) of the integrated circuit Z1 flows into the DC light emission load 4, and Become. Adjustment of the minute dimming current is possible by adjusting the bias value of the gate voltage of the MOSFET Q3 and the resistance value of the resistors R8 and R9.

As described above, the driving device 2 of the step-down converter including the control circuit (integrated circuit Z1) on the high side turns on the bypass circuit 3 in response to the dimming signal to switch the bypass circuit 3 off or on. Even when the value of d is lowered, minute dimming and extinguishing can be achieved.

As mentioned above, although the present invention was described by the embodiment, it should not be understood that the statement and the drawings which form a part of this disclosure limit the present invention. Various alternative embodiments, examples and operation techniques will be apparent to those skilled in the art from this disclosure. That is, of course, the present invention includes various embodiments and the like which are not described herein. Accordingly, the technical scope of the present invention is defined only by the invention-specifying matters according to the scope of claims appropriate from the above description.
For example, the DC power supply of the drive device 2 may be a DC voltage obtained from a commercial AC power supply via an AC rectifying and smoothing circuit configured of a bridge rectifier and a smoothing capacitor.

Reference Signs List 1 lighting device 2 driving device 3 bypass circuit 4 direct current light emission load C1 to C5 capacitor C6 smoothing capacitor D1 and D2 diode E direct current power source L1 reactor LED1 to LEDn direct current light emitting device PC1 photocoupler Q1 switching element Q2 and Q3 MOSFET
R1 Current Sense Resistor R2 to R10 Resistor Z1 Integrated Circuit

Claims (2)

In a DC power supply, a DC light emission load, and a drive device for converting energy obtained from the DC power supply and outputting the energy to the DC light emission load, a switching element, a reactor, and a smoothing capacitor are connected in series to the DC power supply. A step-down type converter in which a regenerative diode is connected in parallel to a series circuit of smoothing capacitors and supplies a DC voltage, which is stepped down by controlling the switching element ON / OFF, to the DC light emitting load, the switching element and the reactor And a bypass circuit connected in parallel to the DC light emission load, wherein the control circuit flows to the DC light emission load. The DC light emitting load according to the current detecting means for detecting the current and the dimming signal from the outside And a current control means for controlling the current flowing, the bypass circuit, when the dimming signal is small dimming or off level, driving apparatus characterized by bypassing the current flowing to the DC light emission load.   The lighting device according to claim 1, comprising the drive device and the direct current light emitting load.