Offset Compensation for Dual Voice Coil Transducers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Electrodynamic acoustic transducers with two voice coils often experience offset issues due to manufacturing design and tolerances, leading to distorted audio output and inaccurate membrane position calculations, especially at high power levels.
Innovation Solution
An electronic offset compensation circuit is applied to the coil arrangement, adjusting the control voltage until the electromotive forces of the voice coils reach a predetermined relation, allowing the transducer to shift to a desired idle position, thereby compensating for offsets and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the first and second coils are mechanically arranged symmetrical to the pole plate in a rest position, then the transducer structure is simplified and manufacturing is easier, but the coils cannot rest in a magnetic zero position due to design specifics and manufacturing tolerances, causing membrane offset
Solution Approach 1:
The patent replaces the mechanical approach of achieving precise magnetic zero position alignment through symmetric coil arrangement with an electronic control system. The control circuit measures the actual positions of the first and second coils relative to the magnetic zero position and applies compensatory control voltages to adjust the membrane position, substituting mechanical precision requirements with electronic correction.
Solution Approach 2:
The patent changes the electrical parameters (control voltages applied to the voice coils) to compensate for positional deviations. By dynamically adjusting the voltage parameters based on measured coil positions, the system achieves accurate membrane positioning without requiring perfect mechanical symmetry in the coil arrangement.
2Device complexity
If the coils are mechanically arranged symmetrical to the pole plate, then device complexity is reduced, but audio output distortion increases at high power levels due to membrane offset from desired position
Solution Approach 1:
The patent implements a feedback control system where the actual positions of the voice coils are measured and fed back to a control circuit. The control circuit processes this information and adjusts the control voltages applied to the coils to maintain the membrane at the desired idle position, thereby eliminating audio output distortion while keeping the mechanical structure simple.
Solution Approach 2:
The patent substitutes the mechanical solution of precisely aligning coils during manufacturing with an electronic control system that actively maintains correct positioning during operation. This electronic substitution allows for simpler mechanical structures while ensuring high audio output quality through active compensation.
3Manufacturing precision
If the coils are mechanically arranged symmetrical to the pole plate, then manufacturing tolerances are easier to meet, but membrane position calculation accuracy decreases due to offset from magnetic zero position
Solution Approach 1:
The patent uses feedback from position sensors to measure the actual locations of the first and second coils relative to the magnetic zero position. This measured information is used by the control circuit to calculate accurate membrane positions and apply appropriate compensatory voltages, ensuring high measurement precision even with simple mechanical arrangements that are easier to manufacture.
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 method effectively reduces audio output distortions, enhances symmetry, and improves membrane position calculation accuracy, ensuring consistent membrane stroke in both directions and preventing damage from high excursions.
Implementation Method 1
The electrodynamic acoustic transducer comprises a membrane, a coil arrangement attached to the membrane and a magnet system being designed to generate a magnetic field transverse to a longitudinal direction of a wound wire of the coil arrangement
Implementation Method 2
a control voltage is applied to at least one of the voice coils and altered until the electromotive force Uemf1 of the first coil or a parameter derived thereof and the electromotive force Uemf2 of the second coil or said parameter derived thereof substantially reach a predetermined relation
Data Source
AI summary
A method for avoiding an offset of a membrane (3) of an electrodynamic acoustic transducer (1) having two voice coils (7, 8) is presented, wherein a control voltage (UCTRL) is applied to at least one of the voice coils (7, 8) until the electromotive force (Uemf1) of the first coil (7) or a parameter derived thereof and the electromotive force (Uemf2) of the second coil (8) or a parameter derived thereof substantially reach a predetermined relation. Furthermore, an electronic offset compensation circuit (12) is presented, which performs the above application of a control voltage (UCTRL). Finally, the invention relates to a transducer system with a transducer (1) and an electronic offset compensation circuit (12) connected to the transducer (1).