Method for multiplying current of LED light bar and associated driving circuit thereof

Patent metadata

Field	Value
Publication number	US-9538593-B2
Application number	US-201213807717-A
Country	US
Kind code	B2
Filing date	Nov 22, 2012
Priority date	Nov 14, 2012
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

The present invention provides a method for multiplying current of an LED light bar, which includes (1) providing a constant current driving chip that includes driving modules each having first to three pins and resistors; (2) providing an LED light bar, a power source, and a PWM control source; (3) connecting an end of one resistor to the third pin of one driving module and an opposite end grounded, connecting the first pin of the driving module to the negative terminal of the light bar, connecting the second pin of the driving module to the PWM control source, and connecting the positive terminal of the light bar to the power source; (4) repeating step (3) as necessary to have multiple driving modules electrically connected to the light bar; (5) activating the power source and the PWM control source to allow the driving modules to simultaneous drive the light bar.

First claim

What is claimed is:

1. A method for multiplying current of a light emitting diode (LED) light bar, comprising the following steps:
(1) providing a constant current driving chip and a plurality of resistors, wherein the constant current driving chip comprises a plurality of constant current driving modules respectively corresponding to the plurality of resistors and each of the constant current driving modules comprises first to third pins;
(2) providing a single LED light bar that comprises a plurality of LEDs, a power source, and a single pulse width modulation (PWM) control source, wherein the LED light bar has a positive terminal and a negative terminal;
(3) connecting an end of a first one of the resistors to the third pin of an associated one of the constant current driving modules and an opposite end to a ground line, connecting the first pin of the associated one of the constant current driving modules to the negative terminal of the single LED light bar, connecting the second pin of the associated one of the constant current driving modules to the single PWM control source, and connecting the positive terminal of the single LED light bar to the power source;
(4) repeating step (3) in such a way as to connect an end of a second one of the resistors to the third pin of an associated one of the constant current driving modules and an opposite end to the ground line, connecting the first pin of the associated one of the constant current driving modules to the negative terminal of the single LED light bar, connecting the second pin of the associated one of the constant current driving modules to the single PWM control source, and connecting the positive terminal of the LED light bar to a power source so as to have the plurality of constant current driving modules electrically connected to the single LED light bar, the plurality of resistors, the power source, and the single PWM control source, wherein the plurality of the constant current driving modules is collectively connected in parallel between the negative terminal of the single LED light source and the single PWM control source with the plurality of the resistors grounded by individually connecting to the ground line and wherein each of the plurality of the constant current driving modules supplies a current flowing completely through the plurality of LEDs of the LED light bar; and
(5) activating the power source and the PWM control source in order to allow the plurality of constant current driving modules to be simultaneously activated by a single signal from the PWM control source to supply the currents to the single LED light bar at the same time to drive the single LED light bar to give off light, wherein the currents supplied from the plurality of constant current driving modules that are simultaneously activated by a single signal from the PWM control source simultaneously flow through the single LED light bar to enhance brightness achieved with the LED light bar in such a way that the current supplied from each of the plurality of constant current driving modules flows completely through the LED light bar.

2. The method for multiplying current of an LED light bar as claimed in claim 1 , wherein the constant current driving modules contained in the constant current driving chip are of a number greater than two and the resistors have a number corresponding to the number of the constant current driving modules contained in the constant current driving chip.

3. The method for multiplying current of an LED light bar as claimed in claim 2 , wherein each of the constant current driving modules comprises a field-effect transistor and a voltage comparator electrically connected to the field-effect transistor, the field-effect transistor comprising a gate terminal, a source terminal, and a drain terminal, the drain terminal being electrically connected to the negative terminal of the LED light bar, the gate terminal being electrically connected to the voltage comparator, the source terminal being electrically connected to the resistor on the third pin of the constant current driving module.

4. The method for multiplying current of an LED light bar as claimed in claim 3 , wherein the voltage comparator comprises a positive pin, a negative pin, and an output pin, the positive pin being electrically connected to the PWM control source, the negative pin being electrically connected to the source terminal of the field-effect transistor, the output pin being electrically connected to the gate terminal of the field-effect transistor.

5. The method for multiplying current of an LED light bar as claimed in claim 4 , wherein the PWM control source supplies high level and low level, the high level being greater than voltage of the source terminal when the field-effect transistor is normally conducted on, the low level being less than the voltage of the source terminal when the field-effect transistor is normally conducted on, the output voltage of the voltage comparator being greater than a threshold voltage of the field-effect transistor.

6. An LED (Light Emitting Diode) light bar driving circuit, comprising a constant current driving chip, a plurality of resistors, a single LED light bar that comprises a plurality of LEDs, a power source, and a single pulse width modulation (PWM) control source, the constant current driving chip comprising a plurality of constant current driving modules respectively associated with the plurality of resistors, each of the constant current driving modules comprising first to third pins, the LED light bar having a positive terminal and a negative terminal, the positive terminal of the LED light bar being electrically connected to the power source, each of the resistors having an end connected to the third pin of an associated one of the constant current driving modules and an opposite end connected to a ground line, the first pin of the associated one of the constant current driving modules that comprises the resistor connected thereto being connected to the negative terminal of the LED light bar, the second pin being connected to the PWM control source, wherein the plurality of the constant current driving modules is collectively connected in parallel between the negative terminal of the single LED light source and the single PWM control source with the plurality of the resistors grounded by individually connecting to the ground line and wherein each of the plurality of the constant current driving modules supplies a current flowing completely through the plurality of LEDs of the LED light bar and the plurality of constant current driving modules are simultaneously activated by a single signal from the PWM control source to supply the currents to the LED light bar at the same time, wherein the currents supplied from the plurality of constant current driving modules that are simultaneously activated by a single signal from the PWM control source simultaneously flow through the single LED light bar to enhance brightness achieved with the LED light bar in such a way that the current supplied from each of the plurality of constant current driving modules flows completely through the LED light bar.

7. The LED light bar driving circuit as claimed in claim 6 , wherein the constant current driving modules contained in the constant current driving chip are of a number greater than two and the resistors have a number corresponding to the number of the constant current driving modules contained in the constant current driving chip.

8. The LED light bar driving circuit as claimed in claim 6 , wherein each of the constant current driving modules comprises a field-effect transistor and a voltage comparator electrically connected to the field-effect transistor, the field-effect transistor comprising a gate terminal,

Assignees

• Zhang Hua
• Shenzhen China Star Optoelect

Inventors

• Zhang Hua

Classifications

• H05B33/0818 Primary

  Electricity · mapped topic

• H05B45/30 Primary

  Driver circuits · CPC title

• H05B45/325

  Pulse-width modulation [PWM] · CPC title