Scanned Beam Display Input via Stylus Timing Correlation
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Solution Overview
Problem
Existing portable scanned beam displays face challenges in providing an effective input function due to the bulkiness of two-dimensional hardware structures required for accurate position detection, which are not suitable for smaller form factor devices like mobile phones.
Innovation Solution
A scanned beam display system that uses a stylus with a photodiode to detect the timing of illumination by a laser beam, correlating it with horizontal and vertical sync signals to determine the X-Y position, allowing for precise input detection without the need for bulky hardware, and optionally using a retroreflector for passive operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two-dimensional hardware structures (capacitive sensing arrays, resistive sensing arrays, wire grid arrays, optical coupling arrays, pressure sensing arrays) are used for position detection, then measurement precision is improved, but device complexity and volume increase making them unsuitable for portable devices
Solution Approach 1:
The patent replaces mechanical/optical hardware sensing structures with a scanned beam optical system. Instead of using capacitive, resistive, or pressure sensing arrays that require two-dimensional hardware structures, the invention uses a light source to scan across the display surface and detect stylus position through optical interactions (light absorption, reflection, or transmission), thereby eliminating bulky hardware while maintaining position detection precision
Solution Approach 2:
The patent transitions from two-dimensional array structures to a time-based one-dimensional scanning approach. Position information is encoded in the temporal dimension through scan timing rather than spatial arrangement of sensors, allowing position detection without requiring a two-dimensional hardware sensing matrix
2Measurement precision
If two-dimensional hardware structures are used for position detection, then measurement precision is improved, but volume of the device increases
Solution Approach 1:
The patent replaces voluminous hardware sensing arrays with a compact scanned beam optical system that uses light to detect stylus position, dramatically reducing device volume while maintaining position detection precision
Solution Approach 2:
The patent encodes position information in the time domain through scan timing rather than using spatially distributed sensors, enabling high-precision position detection with minimal device volume
3Volume of moving object
If a scanned beam system is used for input detection, then device compactness is improved, but the ability to detect input actions may be insufficient
Solution Approach 1:
The patent implements a multi-functional scanned beam system where the same optical scanning mechanism detects multiple input modalities including stylus position, stylus presses (through light absorption), and finger touches (through light reflection or transmission), providing versatile input detection without increasing device volume
Solution Approach 2:
The patent uses light as an intermediary to detect various input actions. The scanned beam interacts with different objects (stylus, finger) through optical properties (absorption, reflection, transmission), enabling the system to distinguish between different input types using the same compact scanning hardware
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 precise and accurate input detection for portable devices, allowing for the use of scanned beam displays in smaller form factors while maintaining a compact design, supporting both two-dimensional and three-dimensional location information, and rotational input capabilities.
Implementation Method 1
The DMD image projector projects a visible image and further projects sequences of infrared illumination patterns that allow the location of the stylus to be determined
Implementation Method 2
The stylus comprises a photodetector that is responsive to infrared radiation at a point toward which the stylus is directed
Implementation Method 3
A light receiving device receives invisible light reflected by a retroreflector of an indicating device that indicates any position on the surface to be scanned
Data Source
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AI summary
Briefly, in accordance with one or more embodiments, an input device may be utilized in conjunction with a scanned beam display (100) or the like, or may be based on the scanning platform as used in a scanned beam display such as a MEMS based scanner. An input event such as illumination of a photodetector or reflection of a scanned beam off of a retroreflector (210) may be correlated with a timing event of the scanning platform such as a refresh signal, or a horizontal and vertical sync signals. The correlation of the timing event may be representative of an X-Y location, and in some embodiments of a Z location, that may be utilized to provide input data back to a host device.