LED Drive Circuit with Reverse Steering Diode for Noise Suppression
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Solution Overview
Problem
Naked LEDs in local circuits without active drive electronics are prone to unintended lighting due to induced noise on the drive signal conductor, and existing methods for vitality checking are not compatible, posing safety risks in applications like railroad signaling.
Innovation Solution
A light emitting diode (LED) drive circuit with a forward and reverse circuit configuration, including steering diodes and resistors, that applies a reverse voltage to counteract induction noise and includes a processor for monitoring current and voltage to ensure proper operation, thereby preventing unintended light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a naked LED is used in a local circuit without active drive electronics, then the circuit complexity is reduced and ease of manufacture is improved, but the LED may light inadvertently due to induced noise on the drive signal conductor
Solution Approach 1:
A reverse steering diode is introduced as an intermediary protective element between the drive signal conductor and the naked LED. This diode conducts during reverse half-cycles and counteracts induced noise, preventing inadvertent LED lighting while maintaining circuit simplicity and manufacturing ease
Solution Approach 2:
The reverse steering diode provides preliminary protection by being pre-configured in the circuit to counteract induced noise before it can cause the LED to light inadvertently. This preventive measure addresses the reliability concern without adding complex active drive electronics
2Measurement precision
If hardware check pulses are used for vitality checking of an LED drive circuit, then the ability to verify circuit operation is improved, but naked LEDs will flash if quickly turned ON-OFF-ON or OFF-ON-OFF
Solution Approach 1:
Instead of using traditional hardware check pulses that quickly switch the LED ON-OFF-ON, the invention inverts the approach by using a reverse steering diode to maintain a steady reverse bias during check operations. This prevents the harmful flashing effect while still enabling vitality checking through monitoring the reverse current
3Reliability
If a reverse bias voltage is applied directly to a light emitting element to prevent light emission, then protection from unintended lighting is improved, but the LED cannot be properly driven in forward direction
Solution Approach 1:
The circuit dynamically switches between reverse bias protection mode (when the LED should be off) and forward drive mode (when the LED should be on). The reverse steering diode provides reverse bias during half-cycles for protection, while the forward steering diode enables proper forward driving during other half-cycles, resolving the contradiction between protection and operability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents unintended lighting of LEDs due to noise induction and allows for integrity checking of the LED drive circuit without turning the LEDs on, enhancing safety and reliability in applications like railroad signaling.
Implementation Method 1
a reverse steering diode electrically connected in series with the resistor, wherein the series combination of the reverse steering diode and the resistor is electrically connected between the first and second terminals, wherein the series combination of the reverse steering diode and the resistor is structured to conduct current in a second direction with respect to the first and second terminals in order that the light emitting diodes are not illuminated
Implementation Method 2
a number of light emitting diodes electrically connected in series, and a forward steering diode electrically connected in series with the light emitting diodes, wherein the series combination of the forward steering diode and the light emitting diodes is electrically connected between the first and second terminals, and wherein the series combination is structured to conduct current in a first direction with respect to the first and second terminals in order to illuminate the light emitting diodes
Data Source
AI summary
A light emitting diode (LED) circuit includes first and second terminals, a forward circuit including a number of LEDs electrically connected in series, and a forward steering diode electrically connected in series with the LEDs. The series combination of the forward steering diode and the LEDs is electrically connected between the first and second terminals, and is structured to conduct current in a first direction with respect to the first and second terminals in order to illuminate the LEDs. A reverse circuit includes a resistor, and a reverse steering diode electrically connected in series with the resistor. The series combination of the reverse steering diode and the resistor is electrically connected between the first and second terminals, and is structured to conduct current in an opposite second direction with respect to the first and second terminals such that the LEDs are not illuminated. An LED drive circuit is also disclosed.