Power Cut-off Delay Circuit for Position Management
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Solution Overview
Problem
Motors continue rotating due to inertia when power is cut off, leading to detection errors in position management systems, which can be costly to resolve using absolute encoders or backup power supplies.
Innovation Solution
A power cut-off delay circuit maintains the position detecting device and storage on power supply, allowing accurate position detection and storage until inertial rotation stops, enabling the use of inexpensive incremental encoders without a backup power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an absolute encoder is used to eliminate detection errors during inertial rotation, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The power cut-off delay circuit performs preliminary action by maintaining power supply to the incremental encoder and counter circuit for a predetermined period after the main power supply is turned off. This allows the system to continue detecting position during inertial rotation before power is actually cut, eliminating detection errors without requiring expensive absolute encoders.
Solution Approach 2:
The invention replaces expensive absolute encoders with inexpensive incremental encoders by introducing a power cut-off delay circuit. The incremental encoder, which is cheaper and simpler, can achieve the same functional result when配合 with the delay circuit that ensures continuous power supply during the critical inertial rotation period.
2Measurement precision
If a backup power supply is provided to maintain position detection during power shutdown, then measurement precision is improved, but use of energy increases
Solution Approach 1:
Instead of continuously powering the incremental encoder and counter circuit, the power cut-off delay circuit implements periodic action by supplying power only during the critical period when inertial rotation occurs after power shutdown. This reduces energy consumption while ensuring position detection accuracy when needed.
Solution Approach 2:
The delay circuit performs preliminary action by anticipating the need for continued position detection after power shutdown and maintaining power supply for a predetermined period. This eliminates the need for a permanent backup power supply, reducing energy consumption while ensuring accurate position tracking during the transition period.
3Loss of time
If power is cut off immediately when the power switch is turned off, then loss of time is reduced, but measurement precision deteriorates due to inertial rotation detection errors
Solution Approach 1:
The power cut-off delay circuit performs preliminary action by automatically extending the power supply period for the position detection system beyond the main power shutdown time. This preliminary extension of power ensures that position detection continues accurately during inertial rotation, resolving the contradiction between quick power shutdown and measurement precision.
Solution Approach 2:
The power cut-off delay circuit acts as an intermediary between the main power supply and the incremental encoder/counter circuit. It mediates the power transmission by delaying the cut-off, allowing the position detection system to continue operating during the transition period when inertial rotation occurs, thus maintaining measurement precision without extending overall system shutdown time.
Data Source
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AI summary
The position management apparatus (7) of the present invention comprises: motors (35, 45) connected to a power supply (61) via a power switch (63); a position detecting device (71, 72, 62) operating by being connected to the power supply and detecting the rotational position of the motors or the drive position of driving members (31, 41) driven by the motors; position storage devices (62, 67) operating by being connected to the power supply and storing the rotational position or the drive position detected by the position detecting devices; and a power cut-off delay circuit (76) for keeping the position detecting devices and the position storage devices connected to the power supply even if the power switch is shut off from a conducting state, and for storing the rotational position or the drive position of the position storage devices after the motor has lost its rotational speed. With this, it is possible to provide a low-cost position management apparatus which accurately manages the drive position of driving members without being affected by the inertial rotation of the motor when the power supply is cut off.