Cradle Position Sensing Using Magnetic Scale to Eliminate Backlash
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Solution Overview
Problem
Existing subject moving apparatuses in imaging systems, such as X-ray CT systems, face challenges in accurately detecting the position of the cradle with high precision due to backlash issues when increasing scanning speed, which affects diagnostic efficiency.
Innovation Solution
A subject moving apparatus equipped with a cradle position sensing mechanism that includes a scale unit and a sensor unit, where the scale unit is extended to cover the sliding range and the sensor unit moves relative to the scale unit to detect the position, allowing for precise calculation of the cradle's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the cradle is moved at increased speed to enlarge scanning range or shorten scan time, then productivity is improved, but measurement precision deteriorates due to backlash in rotary encoder
Solution Approach 1:
The patent replaces the mechanical rotary encoder system with a magnetic scale and sensor unit system. The magnetic scale is attached to the cradle and moves with it, while the sensor unit detects the position by reading the magnetic scale patterns. This substitution eliminates mechanical backlash and contact wear, enabling high-precision position detection even during rapid cradle movement and acceleration, thus resolving the contradiction between improved productivity and maintained measurement precision.
2Productivity
If the cradle is moved at increased speed, then productivity is improved, but reliability deteriorates due to position detection errors
Solution Approach 1:
The magnetic scale and sensor unit system replaces the mechanical rotary encoder, eliminating contact-based detection. The magnetic scale patterns remain stable during rapid movement and acceleration, providing reliable position information without the backlash and wear issues of mechanical systems, thus maintaining reliability while improving productivity.
3Device complexity
If a rotary encoder is used to detect cradle position, then device complexity is reduced, but measurement precision deteriorates under acceleration conditions
Solution Approach 1:
The patent substitutes the mechanical rotary encoder with a magnetic scale and sensor unit system. Although the magnetic scale system has different structural characteristics, it eliminates the backlash mechanism inherent in rotary encoders, providing consistent high-precision position detection during acceleration and deceleration phases of cradle movement.
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 highly precise detection of the cradle's position, improving diagnostic efficiency and enabling quick movements, thereby reducing backlash-related errors.
Implementation Method 1
a sensor unit that is moved relatively to the scale unit in directions, in which the scale unit is extended, along with the slide of the cradle in order to detect the scale of the scale unit
Data Source
AI summary
A cradle position sensing mechanism that includes a scale unit having a scale, which is used to detect the position of the cradle, formed thereon and being extended to cover a sliding range within which the cradle can be slid; and a sensor unit that moves in the directions, in which the scale unit is extended, along with the slide of the cradle so as to detect the scale of the scale unit. The cradle position sensing mechanism serves as a digital linear encoder. Based on the reading on the scale detected by the sensor, the cradle position sensing mechanism calculates the position into which the cradle is slid.