Capacitance-Grating Tape with Self-Adjusting Speed Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing capacitance-grating type digital display measuring tapes face accuracy issues due to inconsistent winding circumference and difficulty in machining, leading to reduced measurement reliability and repeatability, especially with varying tape types and large measurement ranges.
Innovation Solution
A capacitance-grating type digital display measuring tape with a self-adjusting mechanism and a three-piece capacitance-grating sensor structure, including a rotating central shaft, mainspring pre-tightening disc, and double ball bearings, which ensures accurate measurement by adjusting the tape extension/retraction speed and compensating for winding inconsistencies through factory calibration and electronic digital scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-piece type capacitance-grating sensor is used to measure tape length by rotation angle, then the measurement function is realized, but the measurement accuracy cannot be guaranteed due to high requirements on coaxiality of the sensor structure
Solution Approach 1:
The capacitance-grating sensor is divided into three separate components: a transmitting board, a moving grating, and a receiving board. This segmentation allows each component to be independently positioned and adjusted, eliminating the high coaxiality requirements of the two-piece type sensor while maintaining measurement accuracy.
Solution Approach 2:
A moving grating is introduced as an intermediary element between the transmitting and receiving boards. The moving grating rotates with the tape box and interacts with the electric field from the transmitting board, enabling accurate angle measurement without requiring precise coaxial alignment of all sensor components.
2Device complexity
If the capacitance-grating sensor is coaxial with the mainspring box to directly convert rotation angle to display code, then the measurement process is simplified, but the measurement accuracy is affected by inconsistent winding circumference
Solution Approach 1:
The system dynamically tracks the actual rotation angle of the tape box through the moving grating and capacitance-grating sensor, rather than relying on a fixed coaxial relationship. This dynamic measurement approach compensates for winding inconsistencies and maintains accuracy across varying measurement ranges.
Solution Approach 2:
The capacitance-grating sensor provides continuous feedback on the actual rotation angle of the tape box. The single-chip microcomputer uses this feedback to calculate the measurement length, enabling real-time compensation for winding variations and ensuring measurement accuracy.
3Speed
If the tape body extends out or retracts into the shell too fast, then the response speed of the capacitance-grating sensor lags, but the measurement function cannot be completed
Solution Approach 1:
The self-adjusting mechanism pre-adjusts the tape extension and retraction speeds to optimal values before measurement begins. This preliminary speed adjustment ensures that the tape moves at a rate that the capacitance-grating sensor can accurately track, preventing response lag while maintaining measurement function.
Solution Approach 2:
The self-adjusting mechanism automatically monitors and adjusts the tape speed during operation based on the sensor's response characteristics. This self-service function maintains optimal measurement conditions without requiring external intervention, ensuring both speed compatibility and measurement accuracy.
4Ease of operation
If equidistant circular holes are provided in the tape to cooperate with gear for rotation, then the capacitance-grating sensor can be mounted on toothed rotating wheel, but the machining difficulty and cost increase
Solution Approach 1:
The invention extracts the measurement function from the tape structure itself and places it in a separate capacitance-grating sensor system. The tape body no longer requires complex circular holes or gear cooperation, simplifying tape manufacturing while the sensor system provides the measurement capability independently.
Solution Approach 2:
The mechanical gear-and-hole system is replaced with a capacitance-based sensing system. The moving grating and transmitting/receiving boards create an electric field interaction system that measures rotation without requiring mechanical features in the tape, reducing machining difficulty and cost.
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
The solution enhances measurement accuracy and reliability by stabilizing the tape rotation, reducing assembly complexity, and expanding the measurement range through self-adjusting mechanisms and electronic calibration, ensuring consistent and precise length measurements.
Implementation Method 1
capacitance-grating sensor and a single-chip microcomputer, wherein a rotatable central shaft is disposed in the shell in an axial direction thereof; the tape box is coaxially and fixedly connected to a position, corresponding to the back side in the shell, on the central shaft
Implementation Method 2
a mainspring configured to pre-tighten the tape box is disposed in the tape box
Data Source
AI summary
The capacitance-grating type digital display measuring tape includes a shell, a tape box, a tape body and a capacitance-grating sensor. A rotatable central shaft is disposed in the shell in an axial direction thereof. The tape box is mounted at one side in the shell close to the back side in the shell by the central shaft. A mainspring configured to pre-tighten the tape box is disposed in the tape box. The tape body is wound and collected in a groove in the outer circumference of the tape box. The capacitance-grating sensor is located in a position close to the front side in the shell. A self-adjusting mechanism is disposed at a position, corresponding to the outlet, on the inner wall of the shell. The self-adjusting mechanism automatically adjusts the speed at which the tape body extends out of or retracts into the shell.