JP2012079965A - Power unit for led drive - Google Patents

Abstract

A manufacturer or user of a power supply device can freely set the light emission intensity of an LED from a plurality of stages as required.
A regulator unit that stabilizes a DC input for a regulator to generate a DC output, an output detection unit 12 that detects the DC output, and a feedback signal for stabilizing control based on a voltage detected by the output detection unit. A feedback circuit 14 is provided for input to the feedback terminal FB of the regulator unit, and a load LED is driven and illuminated with a DC output stabilized by the regulator unit. A bias amount adjusting circuit 18 in which a resistance value is variable by combining a plurality of bias amount setting resistors and switches is inserted between the reference DC power supply and the feedback terminal of the regulator unit, and the light emission of the LEDs is performed by switching the switches. Strength can be set freely from multiple levels.
[Selection] Figure 1

Description

  The present invention relates to a power supply device for driving an LED. More specifically, the output power can be changed by switching a switch provided inside, and the light emission intensity of the LED as a load can be freely selected from a plurality of stages. The present invention relates to an LED driving power supply device that can be used. This technique is useful for a power supply device for LED lighting, a power supply device for LED signboards, and the like.

  As a power supply device for driving an LED as a load, a current detection resistor is connected to the cathode side of the LED, and feedback is controlled so that the voltage drop at the current detection resistor is kept constant, thereby controlling the LED. There is a circuit configuration that keeps brightness constant by driving with current (see Patent Document 1). In such a conventional power supply device, the output current is set to a predetermined value.

  However, even with the same LED driving power supply device, there are cases where it is desired to change the light emission intensity (brightness) of the LED in accordance with the use conditions and the place of use. Therefore, the power supply device manufacturer needs to prepare a plurality of models set to various output current values according to the user's request.

JP 2003-152224 A

  The problem to be solved by the present invention is to allow the manufacturer or user of the power supply apparatus to freely set the light emission intensity of the LED from a plurality of stages as required.

  The present invention provides a regulator unit that stabilizes a DC input for a regulator to obtain a DC output, an output detection unit that detects the DC output, and a feedback signal for stabilizing control based on a voltage detected by the output detection unit. In a power supply device that includes a feedback circuit that inputs to a feedback terminal of a regulator unit and drives an LED that is a load with a DC output stabilized by the regulator unit, a resistance value combining a plurality of bias amount setting resistors and switches A bias amount adjustment circuit that can be made variable is inserted between a reference DC power supply and the feedback terminal of the regulator unit, and the LED emission intensity can be freely set from a plurality of stages by switching operation of the switch. It is the power supply device for LED drive characterized by these. In the present invention, the number of LEDs serving as a load is not limited to one, and even when a plurality of LEDs are provided in parallel, they can be driven in the same manner, and the light emission intensity can be changed.

  For example, the output detection unit is a current detection resistor connected between the cathode side of the LED serving as a load and the ground, and the feedback circuit includes first and second LED current adjustment resistors connected in series. A feedback signal provided in parallel with the current detection resistor and obtained by dividing the first and second LED current adjustment resistors is input to the feedback terminal of the regulator unit, and the LED as a load is controlled by constant current control. It is configured to drive.

  Alternatively, the output detection unit includes first and second voltage detection resistors connected in series, and is connected in parallel to the LED serving as a load, and the feedback circuit includes the first and first voltage connected in series. Two LED current adjustment resistors are provided in parallel with the second voltage detection resistor, and a feedback signal obtained by dividing the first and second LED current adjustment resistors is input to the feedback terminal of the regulator unit. And it can also be set as the structure which drives said LED used as load by constant voltage control.

  In the LED driving power supply device according to the present invention, the feedback terminal of the regulator unit is pulled up from the reference DC power source with the bias amount setting resistor, and the bias amount setting resistor is selected by the switch. When the manufacturer or the user switches the switch, the light emission intensity of the LED can be freely set from a plurality of stages. This eliminates the need for power supply manufacturers to prepare multiple models with various output current values according to the user's request, and it can be handled with a single model, facilitating production management and inventory management. , Management costs can be reduced.

  Even when the required brightness changes, it can be easily adjusted to an appropriate brightness simply by operating the switch, so that power consumption can be reduced and electricity costs can be saved.

The circuit diagram which shows one Example of the power supply device for LED drive which concerns on this invention. The circuit diagram which shows the other Example of the power supply device for LED drive which concerns on this invention. The circuit diagram which shows the other Example of the power supply device for LED drive which concerns on this invention. The circuit diagram which shows the other Example of the power supply device for LED drive which concerns on this invention.

  The LED drive power supply device is a regulator unit that stabilizes the DC input for the regulator to obtain a DC output, an output detection unit that detects the DC output, and a stabilization control based on a voltage detected by the output detection unit. A feedback circuit for inputting a feedback signal to the feedback terminal of the regulator unit is provided, and an LED serving as a load is driven by a DC output stabilized by the regulator unit. The DC input for the regulator can be obtained by rectifying and smoothing the AC input from the commercial power source. In the present invention, a bias amount adjusting circuit in which a resistance value is variable by combining a plurality of bias amount setting resistors and switches is inserted between a reference DC power source and the feedback terminal of the regulator unit. That is, the feedback terminal of the regulator unit is pulled up from the reference DC power source with the bias amount setting resistor, and the bias amount setting resistor is selected by the switch. The bias amount setting resistance value can be selected by the switching operation of the switch, whereby the light emission intensity of the LED can be freely selected from a plurality of preset levels.

  FIG. 1 is a circuit diagram showing an embodiment of an LED drive power supply device according to the present invention, which is an example of an illumination power supply for driving an LED with a constant current. Basically, the regulator unit 10 that stabilizes the DC input for the regulator to obtain a DC output, the output detection unit 12 that detects the DC output, and the stabilization control based on the voltage detected by the output detection unit 12 And a feedback circuit 14 for inputting a feedback signal to the feedback terminal FB of the regulator unit 10. Here, a 4-terminal series dropper regulator IC is used as the regulator unit 10. This IC has a function of detecting a current flowing through a load (LED) by converting it into a voltage using a load current detection resistor and controlling the output current to be constant. Note that the LED 16 serving as a load is formed by arranging a plurality of LED elements in series.

  The output detection unit 12 is a current detection resistor R1 connected between the cathode side of the LED 16 serving as a load and the ground, and the feedback circuit 14 includes a first LED current adjustment resistor and a first LED current adjustment resistor connected in series. Two LED current adjustment resistors R3 are provided in parallel with the current detection resistor R1, and a feedback signal obtained by dividing the first LED current adjustment resistor R2 and the second LED current adjustment resistor R3 is supplied to the regulator unit 10. The input to the feedback terminal FB is configured to drive the LED 16 serving as a load by constant current control with a DC output stabilized by the regulator unit 10.

  Bias amount adjustment in which a plurality of (here, three) bias amount setting resistors R4, R5, R6 are provided in parallel and the resistance value is variable by combining these bias amount setting resistors R4,. The circuit 18 is configured. As the respective bias amount setting resistors R4,..., R6, resistors having different resistance values are used. The bias amount adjusting circuit 18 is inserted between the reference DC power source Vcc and the feedback terminal FB of the regulator unit 10. One end of all the bias amount setting resistors R4,..., R6 are short-circuited and connected to the reference DC power source Vcc, and the other end of each bias amount setting resistor R4,. The other common contact of the switch SW is connected to the feedback terminal FB of the regulator unit 10. Accordingly, an arbitrary bias amount setting resistor is selected depending on the contact position of the switch SW, and the feedback terminal FB of the regulator unit 10 is pulled up from the reference DC power source Vcc with the selected bias amount setting resistor. The switch SW is usually mounted on a printed board together with various resistors. The reference DC power source Vcc is a power source for operating the 4-terminal series dropper regulator IC.

  Due to the load current flowing through the LED 16 connected in series and the current detection resistor R1, a voltage drop occurs in the current detection resistor R1. The voltage drop is detected and input to the feedback terminal FB of the regulator unit 10 by the feedback circuit 14 so that the detected voltage is kept constant, thereby driving the LED 16 with a constant current. The brightness of the LED 16 is kept constant by a constant current flowing therethrough. Here, since the feedback terminal FB of the regulator unit 10 is pulled up by the bias amount setting resistor from the reference DC power source Vcc having a constant voltage, the bias amount changes when the bias amount setting resistor is changed by the switch SW. The output current of the device, that is, the current flowing through the LED 16 changes, and the brightness changes. Therefore, the light emission intensity of the LED 16 can be freely set from three levels in this embodiment by the switching operation of the switch SW. When the LED 16 is driven at a constant current, the current flowing through the LED 16 is kept constant even when the characteristics of the LED elements vary, so that the brightness can be kept constant.

  FIG. 2 is a circuit diagram showing another embodiment of the LED driving power supply device according to the present invention, which is an example of a lighting power supply for driving an LED with a constant voltage. The basic configuration may be the same as that of the above-described embodiment except for the output detection unit, and corresponding parts are denoted by the same reference numerals for easy understanding. Also here, the regulator unit 10 that stabilizes the DC input for the regulator to obtain a DC output, the output detection unit 20 that detects the DC output, and a feedback signal for stabilization control based on the voltage detected by the output detection unit 20 Is fed to the feedback terminal FB of the regulator unit 10.

  The output detection unit 20 includes a first voltage detection resistor R7 and a second voltage detection resistor R8 connected in series, and is connected in parallel to the LED 16 serving as a load. The feedback circuit 14 is connected in series. The first LED current adjustment resistor R2 and the second LED current adjustment resistor R3 connected to the second LED detection resistor R8 are provided in parallel with the first LED current adjustment resistor R2 and the second LED. A feedback signal obtained by dividing the current adjusting resistor R3 is input to the feedback terminal FB of the regulator unit 10, and the LED 16 serving as a load is driven by constant voltage control.

  A plurality (three in this case) of bias amount setting resistors R4, R5, and R6 are provided in parallel. As the respective bias amount setting resistors R4,..., R6, resistors having different resistance values are used. These bias amount setting resistors R4,..., R6 and the switch SW are combined to constitute a bias amount adjusting circuit 18 having a variable resistance value. The bias amount adjusting circuit 18 is inserted between the reference DC power source Vcc and the feedback terminal FB of the regulator unit 10. One end of all bias amount setting resistors R4,..., R6 are short-circuited and connected to the reference DC power source Vcc, and the other end of each bias amount setting resistor R4,. SW is connected to the feedback terminal FB of the regulator unit 10. Therefore, any one bias amount setting resistor is selected according to the contact position of the switch SW, and the feedback terminal FB of the regulator unit 10 is pulled up from the reference DC power source Vcc with the selected bias amount setting resistor. It becomes.

  The output voltage is divided by the first voltage detection resistor R7 and the second voltage detection resistor R8 connected in series. The feedback circuit 14 inputs the voltage to the feedback terminal FB of the regulator unit 10 so that the voltage is kept constant, thereby driving the LED 16 at a constant voltage. Here, since the feedback terminal FB of the regulator unit 10 is pulled up by the bias amount setting resistor from the reference DC power source Vcc having a constant voltage, the bias amount changes when the bias amount setting resistor is changed by the switch SW. The output current of the device, that is, the current flowing through the LED 16 changes, and the brightness changes. Accordingly, even in the case of constant voltage driving, the light emission intensity of the LED 16 can be freely set from among three levels by the switching operation of the switch SW.

  FIG. 3 is a circuit diagram showing another embodiment of the LED driving power supply device according to the present invention, which is an example of driving a plurality of LEDs in parallel. Since the basic circuit configuration and circuit operation excluding the load are the same as those in FIG. 1, the corresponding parts are denoted by the same reference numerals, and description thereof is omitted. A plurality (two in this case) of LEDs 16 are provided in parallel, and a resistor R9 is provided in series with each LED 16. This resistor R9 suppresses a current difference between the LEDs, and is usually set to about several hundred Ω or less.

  FIG. 4 is a circuit diagram showing another embodiment of the LED driving power supply apparatus according to the present invention, which is an example in which a plurality of LEDs are driven in parallel. Since the basic circuit configuration and circuit operation excluding the load are the same as those in FIG. 2, the corresponding parts are denoted by the same reference numerals, and description thereof is omitted. A plurality (two in this case) of LEDs 16 are provided in parallel, and a resistor R9 is provided in series with each LED 16. This resistor R9 suppresses a current difference between the LEDs, and is usually set to about several hundred Ω or less.

  Thus, when driving several LED16 used as load in parallel, it is preferable to provide resistance R9 in series with each LED16 and to arrange the current value which flows through each LED16. In the example shown in FIG. 3 or FIG. 4 as well, the light emission intensity of the LED 16 can be freely set from three levels by the switching operation of the switch SW.

  In the above embodiment, a four-terminal series dropper regulator IC is used. However, the present invention is not limited to this, and various isolated switching power supplies are used in addition to a step-down chopper circuit and a step-up chopper circuit. be able to.

10 regulator section 12 output detection section 14 feedback circuit 16 LED
18 Bias adjustment circuit 20 Output detector

Claims (3)

A regulator unit that stabilizes the DC input for the regulator to obtain a DC output, an output detection unit that detects the DC output, and a feedback signal for stabilization control based on a voltage detected by the output detection unit. In a power supply device that includes a feedback circuit that inputs to a terminal and drives an LED that is a load with a DC output stabilized by the regulator unit,
A bias amount adjustment circuit in which a resistance value is variable by combining a plurality of bias amount setting resistors and switches is inserted between a reference DC power supply and a feedback terminal of the regulator unit, and LED emission is performed by switching the switches. A power supply device for driving an LED, wherein the strength can be freely set from a plurality of stages.   The output detection unit is a current detection resistor connected to the cathode of the LED serving as a load, and the feedback circuit includes first and second LED current adjustment resistors connected in series in parallel with the current detection resistor. 2. The LED according to claim 1, wherein a feedback signal obtained by dividing the first and second LED current adjustment resistors is input to the feedback terminal of the regulator unit, and the LED serving as a load is driven by constant current control. Driving power supply.   The output detection unit includes first and second voltage detection resistors connected in series. The output detection unit is connected in parallel to the LED serving as a load. The feedback circuit includes first and second feedback circuits connected in series. The LED current adjustment resistor is provided in parallel with the second voltage detection resistor, and a feedback signal obtained by dividing the first and second LED current adjustment resistors is input to the feedback terminal of the regulator unit. The LED driving power supply device according to claim 1, wherein the LED as a load is driven by constant voltage control.

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