Angle Sensor Multiturn Encoding Optical Disc
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current angular sensors for steering columns, such as those in motor vehicles, face challenges in accurately encoding the position over multiple turns due to their reliance on absolute coding over one revolution, which is insufficient for precise positioning, especially at startup, and often require complex mechanical or optical systems that occupy valuable space.
Innovation Solution
An angle sensor with a rotating disc featuring an annular surface divided into cells that transform an incident light beam into an optical code, conveyed by a movable light guide to a fixed photodetector, where the position of the signal relative to the detector determines the turn, utilizing computer-generated holograms and a spiral groove to encode both angular position and turn, reducing the sensor's thickness by integrating the photodetector and light guide on the same plane.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetic technologies with mechanical gear solutions are used to code multiple turns, then the angular position can be encoded over several turns, but the device complexity increases and the volume occupied increases
Solution Approach 1:
The patent replaces mechanical gear solutions with an optical encoding system. A transparent disc with radial opaque zones rotates with the steering column, and light sources positioned at different radii project through the disc to photodetectors. The presence or absence of light signals encodes both the angular position and the turn number, eliminating complex mechanical gears while achieving multi-turn encoding precision.
Solution Approach 2:
The patent uses multiple light sources positioned at different radial distances from the rotation axis to encode multiple turns. Each radial position corresponds to a different turn number, allowing the system to distinguish between turns by detecting which combination of light sources has their beams transmitted through the transparent disc. This dimensional approach (using radial position as an additional encoding dimension) enables multi-turn encoding without mechanical complexity.
2Measurement precision
If magnetic technologies with mechanical gear solutions are used to code multiple turns, then the angular position can be encoded over several turns, but the volume occupied by the sensor increases
Solution Approach 1:
The patent replaces mechanical gear solutions with an optical encoding system. A transparent disc with radial opaque zones rotates with the steering column, and light sources positioned at different radii project through the disc to photodetectors. The presence or absence of light signals encodes both the angular position and the turn number, eliminating complex mechanical gears while achieving multi-turn encoding precision.
Solution Approach 2:
The patent arranges light sources and photodetectors in a compact configuration where multiple light sources are positioned at different radii around the rotation axis, and photodetectors are arranged to receive light from multiple radial positions. This nested arrangement allows multiple encoding functions (angular position and turn number detection) to be integrated in a compact space, reducing the overall sensor volume.
3Duration of action of moving object
If incremental counting of revolutions is used, then the position can be tracked over multiple turns, but the precision at startup is lost
Solution Approach 1:
The patent uses a transparent disc with pre-configured radial opaque zones that encode both the angular position and turn number in a single static configuration. When the steering column starts up, the light sources immediately project through the disc to photodetectors, providing absolute position information from the first moment without requiring incremental counting or initialization sequences. The encoding pattern is预先 prepared on the disc, enabling immediate precise position determination.
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 solution enables precise encoding of the steering wheel's position over multiple turns with a compact design, reducing the overall size of the sensor module and improving accuracy by using a single photodetector to process a single light signal's position change, thereby addressing the limitations of existing systems.
Implementation Method 1
said cells transforming an incident light beam into an optical signal conveying a code of the angular position
Implementation Method 2
said signal then being conducted by a light guide to a fixed photodetector
Implementation Method 3
a fixed photodetector connected to means for processing said code
Data Source
Figure 1~2a
Figure 2b~2c
AI summary
The sensor has a rotating disk (1) endowed of a peripheral annular surface (11) divided by coding cells of an angular position of the disk. A light guide (8) is movable in rotation along an axis parallel to a rotation axis of the disk, and an arm (7) is integrated with the light guide, where the arm is driven in radial speed direction by the rotating disk. The arm displaces the light guide relative to a photo detector (4), and the light guide presents a rectilinear speed section (10) tangentially oriented to the disk.