Phase Difference Detector Using Velocity-Adaptive Clock Pulses
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Solution Overview
Problem
Existing phase difference detection devices experience low precision due to delays in detecting phase differences, especially at high rotation velocities, and are prone to errors from noise, leading to inaccurate rotation position measurements.
Innovation Solution
A phase difference detection device utilizing a reference counter synchronized with a first clock pulse, a velocity detection unit to acquire rotation velocity information, and a pulse conversion unit to output a second clock pulse based on the velocity information, allowing for precise latching and counting of phase differences between a reference signal and a detection signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the frequency of the excitation signal is raised to prevent counter reset before latching, then the measurement reliability is improved, but the device complexity increases
Solution Approach 1:
The invention divides the phase difference detection into two separate counting paths: one for detecting phase difference at the rising edge of the detection signal, and another for detecting phase difference at the falling edge. This segmentation allows each counter to operate independently with its own latching mechanism, preventing the counter reset problem without requiring excessive increase in excitation signal frequency.
Solution Approach 2:
The invention implements preliminary latching of the counter value before the counter is reset. By latching the count value at the appropriate edge of the detection signal and then resetting the counter afterward, the system ensures that the phase difference measurement is captured before potential reset occurs, maintaining measurement reliability without increasing device complexity.
2Measurement precision
If two counters are used to detect phase difference for each cycle, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The invention segments the detection function by using one counter for rising edge detection and another counter for falling edge detection. Each counter is dedicated to a specific edge type, allowing precise phase difference measurement for each cycle while maintaining clear functional separation that simplifies the control logic compared to a single counter handling both edges.
Solution Approach 2:
The invention introduces edge detection circuits as intermediaries that identify the rising and falling edges of the detection signal. These intermediary components trigger the appropriate counter operations, enabling precise phase difference measurement without requiring complex direct control logic in the counters themselves.
3Adaptability or versatility
If the period of the detection signal becomes longer than the excitation signal period at high rotation velocity, then the adaptability is improved, but the measurement precision deteriorates due to counter reset
Solution Approach 1:
The invention performs preliminary latching of the counter value at the appropriate edge of the detection signal before the counter is reset in the next cycle. This preliminary action ensures that the phase difference measurement is captured and preserved even when the detection signal period becomes longer than the excitation signal period at high rotation velocities, preventing measurement precision deterioration.
Solution Approach 2:
The invention implements a feedback mechanism where the latched counter value is used to determine the phase difference, and this information is fed back to control the resetting timing of the counter. This feedback loop ensures that the counter is reset only after the measurement is captured, maintaining measurement precision across a wide range of rotation velocities.
Data Source
Figure 1
Figure 2(a)~2(d)
Figure 3(a)~3(g)
AI summary
A phase difference detection device able to detect a phase with a high precision is provided. A phase difference detection device 4 detecting a phase difference θ between an excitation signal Ss and a second detection signal Sd in accordance with a rotation position θ of a rotary body 101 has a reference counter 13 performing a count in synchronization with a first clock pulse CLK1 and reset when the excitation signal Ss causes zero cross down, a velocity detection unit 19 acquiring information capable of specifying the rotation velocity of the rotary body 101, a pulse conversion unit 21 outputting a second clock pulse CLK2 by using, as a pulse interval Tp, a time specified based on the information acquired by the velocity detection unit 19 and required for the rotation of the rotary body 101 by an angle corresponding to 1 count of the reference counter 13, and a phase counter 23 in which a count value counted by the reference counter 13 is set at an initial value for each fall of a second detection signal Sd, and which performs count in synchronization with the second clock pulse CLK2.