Parallel WLED Light Source for Sensor Testing
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Solution Overview
Problem
Current light sources for testing image sensors, such as CCFL and incandescent lights, are temperature-sensitive, generate excessive heat, and have short lifetimes, while serially connected WLEDs require high voltages and can produce flicker noise, making them unsuitable for mass production environments.
Innovation Solution
A test apparatus using a plurality of White Light Emitting Diodes (WLEDs) connected in parallel as the light source, with a diffuser interface and resistor adjustment unit to ensure stable and uniform test light emission, reducing the required forward voltage and eliminating ripple effects in the voltage waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If CCFL is used as the light source, then the test light can be emitted, but the brightness changes with ambient temperature and flicker noise is generated
Solution Approach 1:
The patent replaces the CCFL gas discharge system with a LED electroluminescence system. LEDs are driven by direct current without ballast circuits, eliminating the electromagnetic interference and flicker noise inherent in CCFL operation. This substitution of the light generation mechanism resolves the brightness stability issue while maintaining adequate illumination intensity for sensor testing.
2Illumination intensity
If incandescent light is used as the light source, then the test light can be emitted, but excessive heat is generated and lifetime is shortened
Solution Approach 1:
The patent replaces the incandescent thermal radiation system with a LED electroluminescence system. Incandescent lights convert most energy to heat with only about 5% becoming visible light, whereas LEDs convert electrical energy directly to light with minimal heat generation. This substitution dramatically reduces heat generation while extending operational lifetime from 100 hours to over 10,000 hours.
3Reliability
If WLED with serial connection is used, then the lifetime is extended and brightness is stabilized, but high forward voltage is required and ripple effects occur
Solution Approach 1:
The patent segments the light source into multiple parallel LED units instead of using a single serial string. By connecting LEDs in parallel, each LED receives the full forward voltage directly from the power supply, eliminating the need for high-voltage boost circuits. This segmentation approach reduces the overall voltage requirement while maintaining stable brightness through individual current control of each parallel branch.
4Illumination intensity
If fluorescent light is used as the light source, then the test light can be emitted, but brightness dims in cold weather and flicker noise is generated
Solution Approach 1:
The patent replaces the fluorescent gas discharge system with a LED solid-state electroluminescence system. Fluorescent lights rely on gas discharge and phosphor excitation that are highly sensitive to temperature variations, causing brightness to dim in cold conditions. LEDs, being solid-state devices, maintain consistent performance across a wide temperature range, ensuring reliable brightness consistency for sensor testing in various environmental conditions.
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 parallel connection of WLEDs provides a stable and long-lasting test light source that is less affected by temperature and voltage changes, ensuring accurate sensor testing without the need for reflectors and minimizing heat generation.
Implementation Method 1
a plurality of light emitting diodes (LEDs) with parallel connection is utilized to be the light source for emitting a test light steadily
Implementation Method 2
The plurality of LEDs is seven-White Light Emitting Diodes (WLED) which receive working current provided by a power supply port to emit the test light
Implementation Method 3
The photo-mask includes at least one diffuser interface. The test light is diffused by the diffuser interface to the outside of the photo-mask
Data Source
AI summary
A light source of testing a sensor, a test apparatus and a method are disclosed. The test apparatus includes a light source, a photo-mask and a sensor bearing area. The light source includes a plurality of light emitting diodes with parallel connection for emitting a test light. The light source is disposed in a photo-mask. The photo-mask has a diffuser interface. The test light is then diffused to the outside of the photo-mask through the diffuser interface. The sensor bearing area is for bearing the sensor. The sensor bearing area is disposed at the outside of the photo-mask and locates at a position to enable the test light to reach. Therefore, the test light emitted by the light source is used to test the sensor.