News Column

Researchers Submit Patent Application, "Circuitry for Current Regulated, Externally Controlled Led Driving", for Approval

July 30, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventor Noller, Armin (Grossbottwar, DE), filed on January 7, 2013, was made available online on July 17, 2014.

No assignee for this patent application has been made.

News editors obtained the following quote from the background information supplied by the inventors: "LED lighting is used for many environments including closed environments like inside of a car. A current driver circuit is used to provide the current of the LED and control its brightness. Different colors of LEDs require different currents to provide the same brightness. Even LEDs of the same color require current adjustment to produce the same brightness. Delivering the same maximum brightness for the LEDs inside a small, closed environment is one task. The other task is providing control over the average current of the LEDs to give the LEDs the capability of being dimmed or brightened while their maximum brightness stays the same. The dimming is generally provided by turning the LED current on and off using pulse width modulation (PWM). The above two tasks are separate from each other and they are independently achieved."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventor's summary information for this patent application: "A circuitry for driving a controlled current is disclosed. An example current driver circuit includes an input node for receiving an input current and an output node for driving an output current and a current mirror (CM) module. The CM module is configured to receive a current at its input node and drive an output current that is multiple times the input current at its output node. The circuitry further includes a solid voltage (SV) module that is configured to receive a reference voltage (VREF). The SV module is coupled to the input node of the current driver circuit and provides the VREF as the voltage of the input node of the current driver circuit. The circuit also includes a current receiving module (CR) coupled to the SV module and coupled to the input node of the current driver circuit. The CR module is configured to receive the input current of the current driver circuit. The CM module is coupled to the CR module and receives the input current of the current driver circuit. The CM module is also coupled to the output node of the current driver circuit. The CM module drives an output current from the output node of the current driver circuit that is multiple times the input current of the current driver circuit.

"The input current of the current driver circuit can be adjusted by coupling a resistor to the input node of the circuit from the first end of the resistor. The resistor or other resistive device can be coupled from the second end to a voltage source where the second end is supplied with a defined voltage. As an example, the resistor is coupled from the second end to the output node of a microcontroller. The input node of the current driver circuit has the constant voltage VREF. The input current of the current driver circuit is the difference of the supplied voltage of the voltage source and VREF divided by the value of the resistor. Therefore, the input current of the current driver circuit is adjustable by the resistor value. The output current of the current driver circuit that is multiple times the input current is also adjustable by the resistor value. The reference voltage (VREF) is a stable voltage and, as an example, is generated by the current driver circuit using a band-gap voltage reference. As an example, the current ratio between the input and output of the current driver circuit is between 10 and 1000 (e.g., 100). As another example, the current driver circuit is included in an integrated circuit chip and controls the lighting of a specific LED color while an external resistor is used for adjusting the current. Multiples of the same circuit are configured into an integrated circuit chip to provide the control for multiple LED colors.

"In another aspect, an example circuit for regulating the current of an LED includes a microcontroller configured to generate PWM waveforms. The microcontroller is coupled through a resistor to the input node of a current driver circuit while an LED is coupled to the output node of the current driver circuit. The current driver circuit is configured to drive an input current it when the output voltage of the microcontroller is on (high). The current driver circuit is also configured to provide a reference voltage (VREF) at its input node. When the output voltage of the microcontroller is on, the input current it is the ratio of the difference between the microcontroller output voltage and VREF divided by the resistor value. Therefore, the input current it is adjustable by the resistor value. The current driver circuit is also configured to drive an output current from its output node that is multiple times its input current. The output current of the current driver circuit which is the same current drawn from the LED is also adjustable by the resistor value. Therefore, the maximum LED current is adjustable by the resistor value. When the output voltage of the microcontroller is off (low), no current flows to the input node of the current driver circuit and no current is driven from the output node of the current driver circuit or the LED. By modifying the duty cycle of the PWM waveform, the microcontroller can change the average current of the LED to modify the LED brightness and dim the LED. When the duty cycle of the PWM pulses is a hundred percent a constant current i1 is drawn at the input of the current driver circuit and a constant current that is multiple times i1 is drawn from the LED. Therefore, the maximum LED brightness is adjusted by the resistor value and dimming is controlled by the PWM waveform.

"An example method is regulating an LED current by a circuit including a voltage source and a current driver circuit. The method includes generating a reference voltage (VREF) by the current driver circuit and applying the VREF to the input node of the current driver circuit. It includes receiving an input current by the input node of the current driver circuit where the input node is coupled through a resistor to the voltage supply and the input current is the difference of the supplied voltage to the resistor and the VREF divided by the resistor value. The method further includes driving an output current that is multiple times the input current from the output node of the current driver circuit and from the LED that is coupled to the output node of the current driver circuit and by changing the value of the resistor controlling the maximum current of the LED. The method also includes incorporating pulse width modulation (PWM) on the voltage source and controlling the average current of the LED. As an example, the voltage source is a microcontroller. As a further example, the current ratio between the input and output of the current driver circuit is between 10 and 1000 (e.g., 100).

"Particular implementations that couple an adjustable resistor between the PWM output of the microcontroller and the input of the current driver circuit configure one node of the current driver circuit to integrate two requirements of the current driver: maximum brightness adjustment and dimming. When the PWM duty cycle is 100 percent, and the pulses are always on, the input and the output currents are constantly flowing and an LED coupled to the output of the current driver circuit is at its maximum brightness. The resistor value is adjusted to control the maximum brightness. When the microcontroller reduces the duty cycle of the PWM waveform, dimming occurs. Therefore, with this implementation, only one node is needed on the current driver circuit to maximum brightness adjustment and to adjust dimming. When the current driver circuit is implemented in an integrated chip then only one pin is required for both maximum brightness adjustment and dimming. Multiples of the same circuit can be integrated into an integrated circuit chip to provide control for multiple LED colors and only one pin per color is required.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a circuit diagram of example current driver circuit.

"FIG. 2 is an example circuit diagram for regulating a light emitting diode.

"FIG. 3 is an example flow diagram of a method for regulating a light emitting diode."

For additional information on this patent application, see: Noller, Armin. Circuitry for Current Regulated, Externally Controlled Led Driving. Filed January 7, 2013 and posted July 17, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=4502&p=91&f=G&l=50&d=PG01&S1=20140710.PD.&OS=PD/20140710&RS=PD/20140710

Keywords for this news article include: Electronics, Light-emitting Diode, Microcontroller, Patents.

Our reports deliver fact-based news of research and discoveries from around the world. Copyright 2014, NewsRx LLC


For more stories covering the world of technology, please see HispanicBusiness' Tech Channel



Source: Electronics Newsweekly


Story Tools






HispanicBusiness.com Facebook Linkedin Twitter RSS Feed Email Alerts & Newsletters