LED Presence and Color Detection Sensor for PCB Testing
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Solution Overview
Problem
Existing methods for testing the presence, brightness, and color of LEDs on printed circuit boards are time-consuming and costly, requiring extensive manual verification and complex calibration, especially when determining color and brightness.
Innovation Solution
A method and apparatus using a sensor with color receptors and an oscillator connected to a processor, allowing for quick and accurate testing of LEDs with constant current or current pulses, featuring a simple assembly and minimal setup, which includes a device with a housing, output probe, and additional probes to provide a single output signal proportional to light detected, and includes protection against overpowering and reverse wiring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual verification of LEDs is performed on a fully rendered printed circuit board, then the operation of LEDs can be verified, but the process is time-consuming and requires powering up the complete board
Solution Approach 1:
The invention separates the LED testing function from the complete PCB assembly by using a standalone sensor device that can test LEDs independently. The sensor unit is a separate component that interfaces with the PCB through simple connections, allowing LED verification without requiring the entire board to be powered up or assembled.
Solution Approach 2:
The sensor device performs LED testing before final PCB assembly or power-up. By conducting preliminary LED presence and functionality checks during manufacturing or assembly stages, the invention prevents defective LEDs from reaching final product, saving time in the long run by avoiding rework or field failures.
2Reliability
If test fixtures with fiber optics are constructed to verify LED operation, then LED testing can be performed, but the fixtures are bulky and expensive
Solution Approach 1:
The invention replaces complex mechanical and optical test fixtures with an electronic sensor-based system. Instead of using bulky fiber optic assemblies and mechanical positioning devices, the patent employs electronic sensors that can be integrated into simple PCB test points, dramatically reducing device complexity while maintaining testing capability.
Solution Approach 2:
The sensor device creates an electrical copy or representation of the LED's light output through photodetection. Rather than physically examining the LED with complex optical equipment, the sensor converts the optical signal into an electrical signal that can be processed electronically, simplifying the overall testing system.
3Measurement precision
If color and brightness of LEDs are determined with extensive calibration, then accurate color and brightness measurement is achieved, but the process requires time-intensive set-up and complex calibration procedures
Solution Approach 1:
The invention uses sensors with multiple color receptors that directly measure different wavelength components of LED light. By changing the measurement parameters from single-wavelength detection to multi-wavelength simultaneous detection, the system achieves accurate color and brightness measurement without requiring iterative calibration procedures.
Solution Approach 2:
The sensor device is designed to perform multiple functions simultaneously: detecting LED presence, measuring brightness, and determining color temperature. This multi-functionality is achieved through a single integrated sensor assembly with multiple receptors, eliminating the need for separate calibration procedures for each measurement type.
4Reliability
If known sensor methods are used to verify LED presence, then verification is achieved, but the sensors cannot sample fast enough when LEDs are biased with current pulses
Solution Approach 1:
The invention employs periodic sampling of the LED output synchronized with the current pulse frequency. The sensor takes measurements at specific intervals that correspond to the LED's active periods, allowing accurate detection of pulsed LEDs. This periodic measurement approach enables the system to capture fast transient signals that continuous sampling might miss.
Solution Approach 2:
The sensor system is designed with dynamic response characteristics that match the speed of modern LED switching. The oscillator and processor are configured to operate at frequencies capable of detecting and measuring fast pulsed LED signals, making the system adaptable to high-speed LED operation rather than being limited by slower sensor response times.
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
Enables faster and more accurate determination of LED presence, brightness, and color, reducing the time and cost associated with previous methods by allowing quicker sampling and more precise measurements, even when LEDs are biased with current pulses.
Implementation Method 1
a sensor having a plurality of color receptors... provides an output signal proportional to light detected from the LED
Implementation Method 2
the LED is biased either with constant current or with a current pulse
Implementation Method 3
light emitting diode (LED)... provides an output signal proportional to light detected from the LED
Data Source
AI summary
A method and apparatus for determining a color and brightness of an LED, when the LED is biased with a current pulse. The apparatus includes a sensor having a plurality of filters and an output probe connected to the sensor, the output probe providing a color output and a brightness output in a single signal. The sensor may further include an input probe connected to the sensor providing power and a ground probe connected to the sensor providing a grounded connection to the sensor. The plurality of filters in the sensor are preferably configured in a matrix array of color receptors having different colors. The method of this invention utilizes pulsing/dynamic sampling to determine a frequency and/or a brightness of the LED output.