Displacement Measurement Head with Early-Stop Phase Detection
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Solution Overview
Problem
Absolute position detection type displacement measuring devices consume a large amount of power due to the need for multiple circuits to operate continuously to acquire phase information across various scales.
Innovation Solution
A displacement measuring device with a detection head that outputs two periodic signals, a demodulator to convert these signals into rectangular scale signals, and a phase detector that stops processing once sufficient phase information is acquired, reducing unnecessary power consumption by switching between multi-drive and single drive signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple circuits operate continuously to acquire phase information across various scales, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic action by controlling circuits to operate only when needed for phase information acquisition. The control circuit activates demodulation and phase detection circuits periodically based on whether phase information is already acquired, rather than maintaining continuous operation. This periodic activation pattern reduces power consumption while ensuring measurement precision is maintained when required.
Solution Approach 2:
The patent applies dynamics by making the operational state of various circuits changeable based on acquisition status. The control circuit dynamically adjusts which circuits are active - switching between states where some circuits operate and others remain inactive. This dynamic control allows the system to adapt power consumption levels according to the current measurement needs and already-acquired information.
2Measurement precision
If all circuits operate until phase information about all scales is acquired, then measurement completeness is improved, but power consumption increases
Solution Approach 1:
The patent extracts and processes phase information for each scale separately and independently. The control circuit identifies which scales have already had their phase information acquired and excludes those from further processing. This extraction approach allows the system to obtain complete measurement information while avoiding unnecessary operation of circuits for scales that are already measured, thereby reducing power consumption.
Solution Approach 2:
The patent implements feedback through the control circuit that monitors the acquisition status of phase information across different scales. Based on this feedback about which scales have been measured, the control circuit adjusts the operation of demodulation and phase detection circuits accordingly. This feedback mechanism ensures measurement completeness is achieved while preventing unnecessary power consumption from redundant operations.
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
Minimizes power consumption by stopping circuit operations once phase information for all scales is acquired, improving power efficiency and reducing unnecessary power usage.
Implementation Method 1
A capacitive encoder includes a main scale and a detection head that is relatively movable to the main scale and detects relative displacement to the main scale. A number of electrodes are disposed on the main scale and the detection head. A periodic capacity change is generated in the electrode patterns according to the relative displacement between the main scale and detection head.
Data Source
AI summary
There is provided a displacement measuring device that minimize unnecessary power consumption and improves power efficiency.A displacement measuring device includes a main scale and a detection head that is provided in such a manner as to be relatively displaceable to the main scale and outputs a periodic signal having a phase to be changed according to relative displacement to the main scale.The detection head outputs, as the periodic signal, a coarse scale signal having a coarse period and a fine scale signal having a fine period. A coarse phase detector calculates, from two pieces of phase information acquired from the coarse scale signal, the average phase of the coarse scale signal. A fine phase detector calculates, from four pieces of phase information acquired from the fine scale signal, the average phase of the fine scale signal. The coarse phase detector calculates the average phase of the coarse scale signal from the two pieces of phase information and, then, stops operating without the completion of the operation of the fine phase detector.