CN102958233B - Power drive circuit and light source device for light emitting diode light source - Google Patents

Abstract

The invention relates to a light source device, which comprises a light emitting module, wherein a first end of the light emitting module is coupled with a floating voltage. In addition, the light source device of the invention also comprises a first charge pump circuit and a second charge pump circuit. The first charge pump circuit and the second charge pump circuit respectively have an output terminal coupled to the second terminal of the light emitting module and have an input terminal coupled to a reference voltage, and the reference voltage is associated with the floating voltage. Particularly, the first charge pump circuit and the second charge pump circuit alternately output driving currents from the output end according to the reference voltage to drive the light emitting diode element in the light emitting module. The invention also provides a power supply driving circuit of the light emitting diode light source. The light source device has thinner volume, and the power driving circuit of the light-emitting diode light source can provide stable driving current to drive the light-emitting diode without being externally connected with a power correction factor loop.

Description

Power drive circuit and light source device for light emitting diode light source

technical field

The invention relates to a power driving circuit, in particular to a power driving circuit and a light source device of a light emitting diode light source.

Background technique

FIG. 1A is a conventional power drive circuit for light emitting diodes. Please refer to FIG. 1A , the power driving circuit 100 can generate a driving current I1 to drive the LED 120 to emit light. The existing power driving circuit 100 includes a rectifying circuit 102 , a rectifying and filtering circuit 104 and a driving circuit 106 . The rectification circuit 102 can be coupled to the mains AC, and output the direct current power DC to the rectification and filtering circuit 104 . Therefore, the rectification and filtering circuit 104 can provide the input voltage Vin to the driving circuit 106 after filtering the direct current power supply DC.

The driving circuit 106 includes a switch 112 , a diode 114 and a capacitor C. The switch 112 couples the anode of the diode 114 to the input voltage Vin, and the cathode of the diode 114 is grounded through the capacitor C and coupled to the anode of the LED 120 . In addition, the LED 120 is connected in parallel with the capacitor C.

FIG. 1B is another conventional LED power drive circuit. Please refer to FIG. 1B , the power driving circuit 140 also includes a rectifying circuit 102 , which is coupled to the mains AC and provides a DC power. In addition, the power supply circuit 140 also includes a switch 112 , a diode 114 and an inductor L. Wherein, the cathode terminal of the diode 114 is coupled to the rectifier circuit 102 to couple to the direct current power supply DC, and the anode terminal of the diode 114 is grounded through the switch 112 . In addition, the anode terminal of the diode 114 is also coupled to the cathode terminal of the LED 122 . The LED 122 is connected in series with the LED 120 , wherein the anode of the LED 120 is also coupled to the cathode of the diode 114 via an inductor L.

When the switch 112 is turned on, the inductor L can store the driving current I1. In contrast, when the switch 112 is turned off, the driving current I1 can be output to drive the LEDs 120 and 122 to emit light. In this prior art, since the inductor L is a current element, it is easy to generate electromagnetic interference. In addition, the inductor L is large and heavy, thus affecting the volume and weight of the overall power driving circuit 140 .

Contents of the invention

Therefore, one of the objects of the present invention is to provide a power drive circuit for a light emitting diode light source, which can provide a stable driving current to drive the light emitting diode light source without an external power correction factor circuit.

In addition, another object of the present invention is to provide a light source device that can have a lighter and thinner volume.

A power supply driving circuit for an LED light source provided by an embodiment of the present invention is suitable for outputting a driving current from an output terminal to drive the LED light source. The power drive circuit provided by this embodiment includes an adjustable constant current source, a first resistor, a second resistor, a first switch, a second switch, a third switch, a fourth switch, a first capacitor and a second capacitor. An adjustable constant current source produces a constant current. The first terminal of the first resistor is coupled to an adjustable constant current source, and its potential is a floating voltage, while the potential of the second terminal of the first resistor is a switch control voltage. The first terminal of the second resistor is coupled to the second terminal of the first resistor, and the potential of the second terminal of the second resistor is a reference voltage. The first terminal of the first switch is coupled to the second terminal of the second resistor and the second terminal thereof is coupled to the first node for coupling to the reference voltage. When the voltage of the first node is lower than the switch control voltage, the first switch is turned on. The action of the second switch is opposite to that of the first switch, and the first end of the second switch is coupled to the first node, and the second end of the second switch is coupled to the output end. Similarly, the third switch operates synchronously with the second switch, the first end of the third switch is coupled to the second end of the second resistor, the second end of the third switch is coupled to the second node, and when the voltage of the second node is less than the voltage of the switch When the voltage is controlled, the third switch is turned on. Relatively, the fourth switch operates synchronously with the first switch. Wherein, the first end of the fourth switch is coupled to the second node, and the second end of the fourth switch is coupled to the output end. In addition, the first terminals of the first capacitor and the second capacitor are coupled to the floating voltage, and the second terminals of the two are respectively coupled to the first node and the second node.

A light source device provided by an embodiment of the present invention includes a light emitting module, the first end of which is coupled to a floating voltage; the second light emitting module includes at least one light emitting diode element. In addition, the light source device in the embodiment of the present invention further includes an adjustable constant current source, a first resistor, a second resistor, a first charge pump circuit, and a second charge pump circuit. An adjustable constant current source produces a constant current. The first terminal of the first resistor is coupled with a constant current and its potential is a floating voltage, and the potential of the second terminal of the first resistor is a switch control voltage. The first terminal of the second resistor is coupled to the second terminal of the first resistor, and the potential of the second terminal of the second resistor is a reference voltage. The first charge pump circuit and the second charge pump circuit respectively have output terminals coupled to the second terminal of the light emitting module, and have input terminals coupled to the reference voltage. In particular, the first charge pump circuit and the second charge pump circuit output driving current from the output end to the light emitting module in turn according to the reference voltage, so as to drive the light emitting diode element.

In an embodiment of the present invention, the above-mentioned first charge pump circuit includes, for example, a first switch, a second switch, and a first capacitor, the first end of the first switch is coupled to the input end of the first charge pump circuit, and the first end of the first switch The second terminal is coupled to the first node, wherein when the voltage of the first node is lower than the switch control voltage, the first switch is turned on; the action of the second switch is inverse phase to that of the first switch, and the first terminal of the second switch is coupled connected to the first node, and its second terminal is coupled to the output terminal of the first charge pump circuit; the first terminal of the first capacitor is coupled to the floating voltage, and its second terminal is coupled to the first node.

In an embodiment of the present invention, the above-mentioned second charge pump circuit includes, for example, a third switch, a fourth switch, and a second capacitor. The first terminal of the third switch is coupled to the input terminal of the second charge pump circuit, and the second terminal of the third switch is coupled to the second node, wherein when the voltage of the second node is lower than the switch control voltage, the third switch conducts The action of the fourth switch is opposite to that of the third switch, and the first terminal of the fourth switch is coupled to the second node, while the second terminal is coupled to the output terminal of the second charge pump circuit; the second capacitor The first end of the FD is coupled to the floating voltage, and the second end is coupled to the second node.

Since the first switch is synchronous with the fourth switch, and the second switch is synchronous with the third switch, and the action of the first switch is opposite to that of the second switch, the first capacitor and the second capacitor will discharge the light-emitting diode element in turn, which can Simply use the adjustable constant current source, when the current value in the constant current source is increased, a larger voltage difference (Vref-V _FG ) will be generated, and a larger LED driving current can be generated at this time. In this way, the present invention does not need an external power factor correction circuit, thereby reducing the overall volume and weight of the circuit.

The above description is only an overview of the embodiments of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , the following preferred embodiments are specifically cited below, and are described in detail as follows in conjunction with the accompanying drawings.

Description of drawings

FIG. 1A and FIG. 1B are conventional power supply driving circuits for light emitting diodes.

FIG. 2 is a circuit block diagram of a light source device according to a preferred embodiment of the present invention.

FIG. 3 is a circuit diagram of a power supply circuit according to a preferred embodiment of the present invention.

FIG. 4 is a circuit diagram of a driving current generating circuit according to a preferred embodiment of the present invention.

Detailed ways

In order to further explain the technical means and effects of the present invention to achieve the intended purpose of the invention, the specific implementation of the power drive circuit and light source device for the light-emitting diode light source proposed according to the embodiment of the present invention will be given below in conjunction with the accompanying drawings and preferred embodiments. Ways, methods, steps, structures, features and effects are described in detail below.

FIG. 2 is a circuit block diagram of a light source device according to a preferred embodiment of the present invention. Please refer to FIG. 2 , the light source device 200 provided in this embodiment includes a power driving circuit 202 and a light emitting module 204 . Wherein, the light emitting module 204 is, for example, a light emitting diode light source, which has at least one (for example, one, or a plurality of series or parallel connection) light emitting diode elements 206 . In this embodiment, the anode terminal of the LED element 206 is coupled to the power driving circuit 202 . Thus, the power driving circuit 202 can output the driving current I1 to drive the light emitting diode element 206 in the light emitting module 204 to emit light.

Please continue to refer to FIG. 2 , the power driving circuit 202 at least includes a driving current generating circuit 216 . The driving current generating circuit 216 is coupled to the light emitting module 204 and to the reference voltage Vref. Therefore, the driving current generation circuit 216 can output the driving current I1 to drive the light emitting module 204 according to the reference voltage Vref, so as to light the LED element 206 .

In some embodiments, the power drive circuit 202 further includes a bridge rectifier circuit 212 and a power circuit 214 . The bridge rectifier circuit 212 is coupled to an AC power source AC, and generates an input voltage Vin to the power circuit 214 . Thus, the power supply circuit 214 can generate the reference voltage Vref to the driving current generation circuit 216 according to the input voltage Vin.

FIG. 3 is a circuit diagram of a power supply circuit according to a preferred embodiment of the present invention. Please refer to FIG. 3 , the power supply circuit 214 provided in this embodiment includes resistors R1 and R2 , and an adjustable constant current source 302 . Wherein, the input end of the adjustable constant current source 302 is coupled to the first end of the resistor R1, and the output end thereof is coupled to the ground potential GND and coupled to the bridge rectifier circuit 212 to generate the constant current Ic. In addition, the potential of the first terminal of the resistor R1 is defined as the floating voltage V _FG , and the potential of the second terminal thereof is defined as the switch control voltage Vsw and is coupled to the first terminal of the resistor R2 . The second end of the resistor R2 is coupled to the driving current generating circuit 216, and its potential is the reference voltage Vref. The following relationship can be obtained from Figure 3:

Vref-Vsw=Ic×R2

Vsw-V _FG =Ic×R1

FIG. 4 is a circuit diagram of a driving current generating circuit according to a preferred embodiment of the present invention. Please refer to FIG. 4 , the driving current generating circuit 216 includes charge pump circuits 402 and 404 , and the actions of the two are opposite to each other. In addition, the input terminals of the charge pump circuits 402 and 404 are commonly coupled to the power supply circuit 214 to be coupled to the reference voltage Vref, and the output terminals thereof are commonly coupled to the light emitting module 204 to supply the driving current I1 to the light emitting module 204 in turn. In this embodiment, the output terminals of the charge pump circuits 402 and 404 are coupled to the anode terminal of the LED device 204 , and the cathode terminal of the LED device 204 is coupled to the floating voltage V _FG .

Please continue to refer to FIG. 4 , the charge pump circuit 402 includes switches 412 and 414 and a capacitor C1 . Wherein, the first end of the switch 412 is coupled to the input end of the charge pump circuit 402 to be coupled to the reference voltage Vref, and the second end of the switch 412 is coupled to the first node N1. In addition, the first terminal of the switch 414 is also coupled to the node N1 , and the second terminal is coupled to the output terminal of the charge pump circuit 402 . A first terminal of the capacitor C1 is coupled to the floating voltage V _FG , and a second terminal is coupled to the node N1. Wherein, the action of the switch 412 is opposite to that of the switch 414 .

Similarly, charge pump circuit 404 includes switches 416 and 418 and capacitor C2. A first terminal and a second terminal of the switch 416 are respectively coupled to the input terminal of the charge pump circuit 404 and the node N2. The first terminal and the second terminal of the switch 418 are respectively coupled to the node N2 and the output terminal of the charge pump circuit 404 . In addition, a first terminal of the capacitor C2 is coupled to the floating voltage V _FG , and a second terminal thereof is coupled to the node N2 . Wherein, the action of the switch 416 is synchronous with that of the switch 414 , and the action of the switch 418 is synchronous with that of the switch 412 .

Please continue to refer to FIG. 3 and FIG. 4. When the potential of the voltage V LED1 of the node N1 is lower than the switch control voltage Vsw, the switch 412 is turned on, and the switch 414 is turned off. At this time, the reference voltage Vref charges the capacitor C1. On the other hand, since switches 416 and 414 are synchronized, and switch 418 is synchronized with switch 412, switch 416 is off and switch 418 is on. At this time, the capacitor C2 will discharge along the path of the switch 418 . Therefore, the charge pump circuit 404 outputs the driving current I1 from the output terminal to the light emitting module 204 to drive the light emitting diode element 206 to emit light.

Relatively, when the potential of the voltage V LED2 of the node N2 is lower than the switch control voltage Vsw, the switch 416 is turned on, and the switch 418 is turned off. In addition, the switch 412 is turned off synchronously with the switch 418 , and the switch 414 is turned on synchronously with the switch 416 . At this time, the capacitor C1 will discharge along the path of the switch 414 . At this time, the charge pump circuit 402 outputs the driving current I1 to the light emitting module 204 from the output terminal. On the other hand, the reference voltage Vref will charge the capacitor C2. It can be seen from the above that the charge pump circuits 402 and 404 output the driving current I1 to the light emitting module 204 in turn.

In summary, the present invention has at least the following advantages:

1. The embodiment of the present invention does not use an inductor as an energy storage element, so there is no problem of electromagnetic interference.

2. Since the embodiment of the present invention configures at least two charge pump circuits, they will supply the driving current in turn to drive the light-emitting diode element when the voltage stored in the capacitor is lower than the default voltage value, so that the reference voltage Vref and the floating voltage V _FG can be changed The voltage difference changes the driving current so that the current is proportional to the input voltage. Therefore, the present invention does not require an additional power correction factor circuit.

3. Because in the charge pump circuit, one end of the capacitor is coupled to a floating voltage instead of the ground voltage, and this floating voltage is associated with the reference voltage, so the driving current will not be affected by the drift of the reference voltage.

4. In this circuit, since there is no large inductance that generates a magnetic field, no high-power electromagnetic waves will be generated.

5. The power consumed in the power supply circuit is only the power consumed by the current flowing through the resistors R1 and R2, so the power loss of the present invention is very low.

The above description is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this field Those skilled in the art, without departing from the scope of the technical solution of the present invention, may use the technical content disclosed above to make some changes or modify them into equivalent embodiments with equivalent changes, but if they do not depart from the content of the technical solution of the present invention, the Technical Essence Any simple modifications, equivalent changes and modifications made to the above embodiments still fall within the scope of the technical solution of the present invention.

Claims (4)

1. a power driving circuit for LED source, be suitable for, from output output driving current to drive described LED source, it is characterized in that, described power driving circuit comprises:

Adjustable constant current source, produces continuous current;

First resistance, its first end couples the input of described adjustable constant current source, and the current potential of described first end is floating voltage, and the current potential of the second end of described first resistance is switch control voltage;

Second resistance, its first end is coupled to the second end of described first resistance, and the current potential of the second end of described second resistance is reference voltage;

First switch, its first end couples the second end of described second resistance and its second end is coupled to first node, to couple described reference voltage, when the voltage of described first node is less than described switch control voltage, described first switch conduction;

Second switch, its action and described first switch inverse, and the first end of described second switch is coupled to described first node, its second end is then coupled to described output;

3rd switch, with described second switch synchronization action, the first end of described 3rd switch couples the second end of described second resistance and its second end is coupled to Section Point, when the voltage of described Section Point is less than described switch control voltage, and described 3rd switch conduction;

4th switch, with described first switch synchronization action, and the first end of described 4th switch is coupled to described Section Point, and its second end is then coupled to described output;

First electric capacity, its first end couples described floating voltage, and its second end is then coupled to described first node; And

Second electric capacity, its first end couples described floating voltage, and its second end is then coupled to described Section Point.

2. a light supply apparatus, is characterized in that comprising:

Adjustable constant current source, produces continuous current;

First resistance, its first end couples the input of described adjustable constant current source, and the current potential of described first end is floating voltage, and the current potential of the second end of described first resistance is switch control voltage;

Second resistance, its first end is coupled to the second end of described first resistance, and the current potential of the second end of described second resistance is reference voltage;

Light emitting module, comprises at least one light-emitting diode, and the first end of described light emitting module couples described floating voltage;

First charge pump circuit, has the output of the second end coupling described light emitting module, and the input with the second end being coupled to described second resistance is to couple described reference voltage; And

Second charge pump circuit, there is the output of the second end coupling described light emitting module, and couple the input of the second end of described second resistance, described first charge pump circuit and described second charge pump circuit give described light emitting module, to drive described light-emitting diode from output output driving current in turn according to the voltage of the voltage of the output of described first charge pump circuit, the output of described second charge pump circuit and described switch control voltage.

3. light supply apparatus according to claim 2, is characterized in that, described first charge pump circuit comprises:

First switch, its first end couples the input of described first charge pump circuit, and its second end is coupled to first node, when the voltage of described first node is less than described switch control voltage, described first switch conduction;

Second switch, its action and described first switch inverse, and the first end of described second switch is coupled to described first node, its second end is then coupled to the output of described first charge pump circuit; And

First electric capacity, its first end couples described floating voltage, and its second end is then coupled to described first node.

4. light supply apparatus according to claim 2, is characterized in that, described second charge pump circuit comprises:

3rd switch, its first end couples the input of described second charge pump circuit, and its second end is coupled to Section Point, and when the voltage of described Section Point is less than described switch control voltage, described 3rd switch conduction;

4th switch, its action and described 3rd switch inverse, and the first end of described 4th switch is coupled to described Section Point, its second end is then coupled to the output of described second charge pump circuit; And

Second electric capacity, its first end couples described floating voltage, and its second end is then coupled to described Section Point.