Electronic Pen Compact Optical Path Using Diffraction
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Solution Overview
Problem
Conventional pointing devices require a significant optical path length to detect movement, leading to increased device size and limited design flexibility.
Innovation Solution
The electronic pen incorporates a light source, a rotating body, and a first diffraction element that diffracts and reflects light to enable accurate movement detection and click operation, with a compact design achieved by optimizing the arrangement of optical elements and using a diffraction element to branch light beams, reducing the need for multiple light sources and enhancing the degree of freedom in optical element placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional pointing device uses a ball and optical image sensor to detect movement, then movement detection functionality is achieved, but the device size increases due to the required optical path length
Solution Approach 1:
The patent transitions from a two-dimensional detection plane to a three-dimensional optical path by introducing a rotating body that reflects light back along the same path. This allows the optical detection to occur in multiple dimensions (forward and backward along the optical axis) rather than requiring a large lateral space, thereby reducing device volume while maintaining detection precision
Solution Approach 2:
The patent nests the optical detection path within itself by using the rotating body to reflect light back through the same optical components (light source and detection member). This nested configuration allows the optical path to fold back on itself, eliminating the need for a large linear optical path length and reducing the overall device size
2Measurement precision
If multiple light sources are used to illuminate the ball from different directions, then movement detection accuracy is improved, but power consumption increases
Solution Approach 1:
The patent makes the single light source perform multiple functions by using the rotating body to redirect it. The same light source illuminates the ball from different effective angles as the ball rotates, providing multi-directional illumination capability without requiring multiple physical light sources, thus reducing power consumption while maintaining detection accuracy
Solution Approach 2:
The rotating ball serves its own illumination needs by reflecting light from the single light source back toward the detection member. The rotation of the ball itself creates the varying illumination angles needed for accurate movement detection, eliminating the need for external multi-directional lighting systems and reducing overall power consumption
3Volume of moving object
If a compact optical path is designed to reduce device size, then device size is reduced, but the degree of freedom in arranging optical elements is limited
Solution Approach 1:
The patent introduces dynamic elements (the rotating body) into the optical path that can change the direction and path of light in real-time. This dynamic capability allows the optical system to adapt to different configurations and maintain flexibility in arranging optical elements within a compact space, overcoming the rigidity constraints of static compact designs
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 allows for a smaller device size while maintaining accurate movement detection and click operation functionality, improving detection accuracy and reducing power consumption.
Implementation Method 1
a first diffraction element provided at an optical path from the light source to the first detection member and configured to diffract the irradiation light
Implementation Method 2
a rotating body configured to rotate and to reflect the irradiation light emitted from the light source
Data Source
AI summary
An electronic pen includes a light source configured to emit irradiation light, a rotating body configured to rotate and to reflect the irradiation light emitted from the light source, a first detection member configured to receive the irradiation light reflected by the rotating body, and a first diffraction element provided at an optical path from the light source to the first detection member and configured to diffract the irradiation light.