Distance Sensing Module Light Guide Structures Total Internal Reflection
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Solution Overview
Problem
Current distance sensing technologies, such as Time of Flight (ToF) sensing devices, suffer from low light collection efficiency due to a significant portion of the light spot falling outside the sensing areas, resulting in poor light absorption by silicon-based sensing elements.
Innovation Solution
A distance sensing module is designed with a light guide layer featuring light guide structures that utilize total reflection to gather sensing light on the sensing areas, increasing light collection efficiency by directing light from the light transmission layer to the sensing areas via the principle of total reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a giant microlens (GML) is used to condense light to increase effective fill factor, then the light collection area is improved, but a portion of the focused light spot still falls outside the sensing areas, resulting in low light collection efficiency
Solution Approach 1:
The patent divides the light guiding function into multiple segments: the microlens focuses light, the light guide layer with multiple light guide structures directs the light, and the sensing areas detect the light. This segmentation allows each component to optimize its function, with the light guide structures specifically designed to channel light precisely to the sensing areas, solving the problem of light falling outside the sensing regions.
Solution Approach 2:
The light guide layer acts as an intermediary between the microlens and the sensing areas. It includes multiple light guide structures that receive light from the microlens and guide it to the sensing areas, ensuring that the focused light is properly directed and utilized, thereby improving light collection efficiency.
2Device complexity
If the sensing areas occupy only a portion of the sensing element, then the device structure is simplified, but the overall light collection efficiency is poor
Solution Approach 1:
The light guide layer serves as an intermediary structure that bridges the gap between the simple sensing area design and the need for high light collection efficiency. It captures light that would otherwise be lost and directs it to the sensing areas, maintaining structural simplicity while improving energy utilization.
Solution Approach 2:
The patent changes the optical parameters by introducing the light guide layer with specific refractive index properties. This parameter change enables total internal reflection within the light guide structures, allowing efficient light guidance to the sensing areas without increasing the complexity of the sensing elements themselves.
3Device complexity
If light is transmitted directly to sensing areas without light guide structures, then the device structure is simpler, but light loss occurs and sensing effect is reduced
Solution Approach 1:
The sensing pixel is segmented into functional layers: the light guide layer with multiple light guide structures is separated from the sensing areas. This segmentation allows the light guide structures to pre-process the light by directing it precisely to the sensing areas, improving measurement precision without significantly increasing overall structural complexity.
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 design enhances the amount of received light, improving the overall sensing effect by reducing light loss and increasing the efficiency of light utilization within the sensing pixels.
Implementation Method 1
the light guide layer includes a plurality of light guide structures, and each of the plurality of light guide structures has a first side and a second side opposite to each other. The plurality of second sides are coupled to the plurality of sensing areas. When the sensing light is transmitted to the plurality of light guide structures in the light guide layer, the sensing light may be gathered on the sensing areas via the principle of total reflection
Data Source
AI summary
A distance sensing module includes a first substrate, an upper cover, a light-emitting unit, and at least one sensing pixel. The upper cover is disposed on the first substrate to form an accommodating space. The light-emitting unit is disposed at an emitting end in the accommodating space. The sensing pixel is disposed at a receiving end in the accommodating space and includes a second substrate disposed in the accommodating space and having a top surface, sensing areas disposed in the second substrate and exposed on the top surface, a light guide layer including light guide structures having first sides connected to a light transmission layer and second sides coupled to the sensing areas, a lens layer including at least one lens, and the light transmission layer between the light guide layer and the lens layer. The light guide layer is between the second substrate and the light transmission layer.