Passive Rotary Knob Angle Detection on Touch Screen
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Solution Overview
Problem
Capacitive sensor arrays struggle to accurately detect the rotational angle of passive dials that partially or fully overlap touch screens, as existing technologies require conductive elements and on-board electronics, limiting their application in space-constrained environments like cars.
Innovation Solution
Implementing a capacitive sensor array system that uses a plurality of conductive indexes on a passive dial, which rotate and create capacitive coupling with the touch screen, allowing the touch screen controller to detect the dial's rotational angle through capacitance changes, without the need for on-board electronics or power, using conventional capacitive sensing techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional capacitive sensing techniques are used to detect passive dials, then the dial structure is simplified without on-board electronics, but measurement precision of rotational angle deteriorates due to partial overlap and capacitance signal ambiguity
Solution Approach 1:
The dial is segmented into multiple conductive indexes (at least two) that are distributed around the rotational perimeter. Each index independently generates capacitive coupling with the touch screen, allowing the system to detect rotational position through multiple discrete capacitance signals rather than relying on a single ambiguous signal, thereby improving measurement precision while maintaining structural simplicity
Solution Approach 2:
The conductive indexes serve as intermediaries between the passive dial and the capacitive sensor array. These indexes create controlled capacitive coupling with the touch screen surface, translating mechanical rotation into detectable electrical signals without requiring electronics on the dial itself, thus resolving the contradiction between structural simplicity and detection precision
2Ease of manufacture
If passive dials without on-board electronics are used, then ease of manufacture and adaptability improve, but reliability of angle detection deteriorates in harsh conditions
Solution Approach 1:
The passive dial with conductive indexes utilizes the touch screen's own capacitive sensing capability to detect rotation, eliminating the need for separate power sources, electronics, or complex sensing mechanisms on the dial. The dial essentially uses the touch screen's field for detection, improving ease of manufacture while maintaining reliability through the robustness of capacitive sensing in harsh environments
Solution Approach 2:
The conductive indexes serve multiple functions: they maintain the passive mechanical structure of the dial for ease of manufacture, while simultaneously enabling reliable angle detection through capacitive coupling. The same structural elements that simplify manufacturing also provide the sensing function, ensuring reliability without adding complexity
3Measurement precision
If conductive indexes are added to passive dial, then measurement precision of rotational angle improves through multiple capacitance signals, but device complexity increases
Solution Approach 1:
The conductive indexes are merged with the existing dial structure rather than being separate components. The indexes are integrated into the dial body or attached as simple conductive elements, combining the mechanical rotation function with the electrical sensing function in a single unified structure, thus improving measurement precision without significantly increasing overall device complexity
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
Enables reliable detection of the rotational angle of passive dials in touch screens, even in harsh conditions, by converting capacitance signals into digital values for precise angle calculation, enhancing user interface functionality in space-constrained applications.
Implementation Method 1
Capacitive sensor technology functions by measuring the capacitance of a capacitive sensor element (i.e., sensor), and evaluating for a change in capacitance caused by a conductive element that touches or is near the sensor.
Implementation Method 2
the at least one of the indexes are proximate to a face of the active area and move in conjunction with a rotation of the passive dial
Data Source
AI summary
An apparatus and method for detecting the angle of passive rotary knob partially located on a touch screen are described. In embodiments the apparatus includes a touch screen having an array of sensors and a dial that includes a base and a knob attached to the base and rotatable relative to the base. The knob includes a plurality of conductive elements, each positioned a distance from a center point of the knob. A controller is also included, coupled to the touch screen, and configured to receive signals generated by one or more sensors of the array in response to the sensors detecting one or more of the conductive elements. The controller can determine a rotational angle of the knob based on the signals generated by the one or more of the sensors in the array while a portion of the knob does not overlap the array of sensors.