GMR Sensor Rotary Knob for Direction Detection
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Solution Overview
Problem
Rotary knobs in sash locks face challenges in recognizing door lock/unlock states due to limited space, potential dirt accumulation, and complex data analysis for slotted disks, which affects operational safety and energy efficiency.
Innovation Solution
A sensor device with a pair of sensors and a counter-element arranged for circular movement, using GMR sensors and an evaluation circuit to detect direction and rotation without complex structures, enabling simple and energy-efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If incremental encoders are used in rotary knobs, then rotational direction detection is possible, but the space required increases beyond what is available in compact rotary knobs
Solution Approach 1:
The detection path is segmented into multiple discrete detection areas arranged along a circular path. Each sensor detects passage through its specific detection area, and the sequence of detection across multiple areas enables direction determination without requiring a continuous complex encoder structure.
Solution Approach 2:
The invention transitions from using a complex two-dimensional encoder disk to a one-dimensional linear arrangement of sensors along a circular path. The counter element moves linearly through sequential detection areas, converting rotational motion detection into a simpler linear detection sequence that requires less space.
2Measurement precision
If slotted disks are used for rotation detection, then rotational movement can be detected, but dirt accumulation on the slotted disk impairs operational safety
Solution Approach 1:
The mechanical slotted disk structure is replaced with a magnetic field-based detection system. The counter element with magnetic poles and GMR sensors detect rotational position through magnetic field interactions, eliminating the need for physical slots that can accumulate dirt and compromise reliability.
3Measurement precision
If slotted disks with complex structures are used, then rotation detection is possible, but the data analysis required to detect rotation direction becomes complex
Solution Approach 1:
The system prepares direction detection in advance by using multiple sensors positioned at different locations along the circular path. The sensors are arranged to detect the counter element's passage in a predetermined sequence, so that when rotation occurs, the direction is already determined by which sensor detects the passage first, eliminating complex real-time analysis.
Solution Approach 2:
The evaluation circuit continuously monitors the output signals from all sensors and uses feedback from the detection sequence to determine rotation direction. When a sensor detects the counter element's passage, this feedback signal immediately provides direction information based on the predetermined detection area arrangement, simplifying the evaluation logic.
4Measurement precision
If the reader is kept active continuously to detect door lock/unlock states, then immediate detection is possible, but energy consumption increases
Solution Approach 1:
The reader operates periodically rather than continuously, being activated only when the counter element passes through a detection area and triggers the evaluation circuit. This periodic activation based on rotational events maintains the ability to detect door lock/unlock states while significantly reducing overall energy consumption compared to continuous operation.
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 allows for accurate detection of rotation direction and change in direction without complex logic, saving space and reducing operational complexity while enhancing energy efficiency by activating controls only during short impulses.
Implementation Method 1
The sensors are preferably formed by means of GMR sensors. i.e. the counter-element is magnetized magnetically or, for example, electrically. This offers the possibility of simply being able to use the electrical resistance of the sensors as a measured variable.
Data Source
Figure 1a~1b
Figure 2a~2d
Figure 3a~3b
AI summary
A sensor device according to the invention is equipped to be used in a rotary knob (120) of a knob cylinder (100). The sensor device has at least one pair of sensors (125) and a counter-element (113). Said counter-element (113) and the at least one pair of sensors (125) are disposed so as to be movable relative to one another along a circular movement path. The counter-element (113) and the sensors (125) are located opposite one another in such a way that the detection regions (126) of the sensors (125) enclose a respective sub-region of the movement path and partially overlap one another in the region of the movement path. The movement path extends partially outside the detection regions (126) of the at least one pair of sensors (125). A rotary knob (120) according to the invention is disposed so as to be freely rotatable relative to a lock bit (111) of a profiled cylinder (110) and can be activated in such a way that, for the time of activation, the rotary knob (120) energizes an actuator which is rotationally operatively connected to the lock bit (111) in such a way that said actuator rotates the lock bit in a predetermined direction. The rotary knob (120) comprises a reader (121) which is designed to read data of a code card. Furthermore, the rotary knob (120) comprises the aforementioned sensor device.