Surface Emitting Laser Device with Integrated Light Receiving Elements
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Solution Overview
Problem
The challenge is to create a downsized surface emitting laser device for portable information terminals that can accurately measure distance using the time of flight method without the limitations of integrated light emitting and receiving elements, which face difficulties in downsizing and maintaining distance measurement accuracy.
Innovation Solution
The device incorporates a surface emitting laser with multiple light emitting elements on a substrate, where some elements act as both light emitters and receivers, utilizing a forward bias for emission and reverse bias for reception, and an optical system to manage light output and reception, allowing for variable control of light intensity and timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate light receiving elements are provided to detect emission timing and receive reflected light, then distance measurement accuracy is improved, but device size increases making it unsuitable for portable terminals
Solution Approach 1:
The patent combines multiple light receiving elements into a single integrated element that can perform both functions: detecting the emission timing of the light emitting element and receiving the reflected light from the subject. This merging eliminates the need for separate light receiving elements, thereby reducing device size while maintaining the capability to perform accurate distance measurement using the time of flight method
Solution Approach 2:
The light receiving element is designed with multi-functionality to serve multiple purposes within the distance measurement system. It acts as both a timing detector for the emitted light and a receiver for the reflected light, allowing a single component to fulfill roles that would traditionally require separate dedicated elements, thus enabling device downsizing for portable terminals
2Volume of moving object
If light receiving elements are integrated into one, then device size is reduced, but reception of reflected light from short distance fails narrowing measurement range
Solution Approach 1:
The patent implements dynamic control of the light receiving element's operation mode. The element can switch between detecting the emission timing and receiving reflected light, and this switching is controlled adaptively based on the measurement requirements. This dynamic operation allows the integrated element to maintain reliable performance across different distance ranges, including short distances, by optimizing its reception characteristics for each specific measurement scenario
3Device complexity
If a single light receiving element detects both emission timing and reflected light, then device complexity is reduced, but light reception reliability deteriorates due to quenching operation requirements
Solution Approach 1:
The patent employs periodic action by implementing time-division multiplexing where the light receiving element alternates between different operational states. The element performs quenching operations in a periodic manner that is synchronized with the light emission and reception cycles. This periodic operation allows the single integrated element to reliably detect both emission timing and reflected light by dedicating specific time periods to each function, thereby maintaining reception reliability despite the reduced component count
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 configuration enables accurate distance measurement even in low-contrast environments, reduces the need for separate light receiving elements, and allows for a compact design suitable for portable devices without compromising measurement range or accuracy.
Implementation Method 1
a first element that emits light
Implementation Method 2
a second element that receives light which is the light emitted from the first element and reflected by the optical system
Data Source
AI summary
To enable downsizing and prevent an adverse effect on distance measurement.A surface emitting laser device includes a surface emitting section having a plurality of light emitting elements arranged on a substrate, and some of the plurality of light emitting elements are used as light receiving elements.