Miniaturized Optical Proximity Sensor Molded Infrared Shield
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Solution Overview
Problem
Existing optical proximity sensors rely on metal shields for crosstalk reduction, which are difficult to manufacture in high volumes, costly, and prone to detachment, making them unsuitable for smaller, more reliable devices.
Innovation Solution
The design eliminates the need for a metal shield by using a substrate with wire bond pads, an infrared light emitter, a light detector, an integrated circuit, spacers, and molded infrared light pass and cut components to minimize crosstalk and interference, while maintaining high performance and manufacturability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal shield is used to reduce crosstalk between light emitter and light detector, then optical isolation is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent integrates the light emitter, light detector, and optical isolation structures into a single substrate. The optically opaque regions are formed directly on the substrate surrounding the light emitter, eliminating the need for separate metal shields and their associated complex assembly processes.
Solution Approach 2:
The patent removes the metal shield component entirely from the design. Instead of using a separate metal shield for optical isolation, the invention uses optically opaque regions formed directly on the substrate, simplifying the overall device structure and manufacturing process.
2Reliability
If a metal shield is used to reduce crosstalk, then optical isolation is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines the substrate and optical isolation structures into a single integrated component. The optically opaque regions are formed directly on the substrate during the same manufacturing process, eliminating the need for separate metal shield components and reducing overall manufacturing cost.
Solution Approach 2:
The patent replaces expensive metal shields with inexpensive optically opaque regions formed directly on the substrate. This substitution significantly reduces material costs and manufacturing expenses while maintaining effective optical isolation.
3Reliability
If a metal shield is used to reduce crosstalk, then optical isolation is improved, but device reliability decreases due to detachment issues
Solution Approach 1:
The patent integrates the optical isolation structures directly into the substrate, eliminating separate metal shield components that require assembly. This integration ensures permanent optical isolation without the risk of detachment or misalignment during device operation.
Solution Approach 2:
The patent removes the metal shield component entirely, eliminating the assembly step of attaching metal shields to the sensor. This extraction of the problematic component resolves the detachment issues and simplifies the overall device architecture.
4Area of moving object
If the sensor size is reduced for smaller devices, then device compactness is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent integrates all components (light emitter, light detector, optical isolation structures) into a single substrate with a compact footprint of approximately 4.0 mm x 2.0 mm. This integration eliminates the need for precise alignment of separate components, reducing manufacturing precision requirements despite the small size.
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
This approach results in a smaller, more reliable optical proximity sensor with reduced crosstalk and interference, lower manufacturing costs, and improved reliability, achieving an 85% reduction in footprint compared to previous designs.
Implementation Method 1
an infrared light emitter mounted atop the substrate and electrically connected to at least one of the wire bond pads
Implementation Method 2
a light detector mounted atop the substrate and electrically connected to at least one of the wire bond pads
Implementation Method 3
a molded substantially optically non-transmissive infrared light cut component disposed between the first and second molded optically transmissive infrared light pass components and over portions of the substrate, the molded substantially optically non-transmissive infrared light cut component configured to block and absorb scattered or reflected light so as to minimize optical crosstalk
Data Source
AI summary
Various embodiments of a miniaturized optical proximity sensor are disclosed. In one embodiment, an ambient light sensor and a light detector are mounted on first and second spacers, which in turn are mounted to a top surface of an integrated circuit die-attached to a substrate. An optically-transmissive infrared pass compound is molded over the ambient light sensor, the light detector, the integrated circuit, a light emitter and peripheral portions of the substrate. Next, an optically non-transmissive infrared cut compound is molded over the optically-transmissive infrared pass compound to provide a miniaturized optical proximity sensor having no metal shield but exhibiting very low crosstalk characteristics.