Touch Sensor Vibration Interference Mitigation
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Solution Overview
Problem
Capacitive touch sensors face interference from electric fields generated by vibration mechanisms used for providing tactile feedback, leading to inaccurate detection of contact positions due to the close proximity required for effective vibration transmission in small devices like mobile phones.
Innovation Solution
A tactile sensation providing apparatus with a tactile sensation unit that vibrates the touch sensor, a control unit to detect contact positions, and signal lines that avoid overlapping with the vibration unit, ensuring that scanning and vibration periods do not overlap to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a tactile sensation providing unit is disposed near the touch sensor to vibrate the touch sensor, then tactile feedback is provided to the operator, but the electric field generated by the vibration mechanism interferes with the detection of contact position
Solution Approach 1:
The patent divides the touch sensor into multiple detection regions (first detection region and second detection region) with different detection mechanisms. The first detection region uses a mechanism insensitive to the vibration electric field, while the second detection region handles other detection tasks, thereby isolating the detection function from the interference zone
Solution Approach 2:
Different regions of the touch sensor are assigned different detection qualities or characteristics. The first detection region is specifically designed with properties that make it resistant to the electric field interference from the vibration mechanism, while other regions may use different detection approaches
2Power
If the driving mechanism is placed close to the touch sensor for effective vibration transmission in small devices, then vibration efficiency is improved, but the electric field from the driving mechanism interferes with touch sensor detection
Solution Approach 1:
The patent introduces a signal line configuration that acts as an intermediary between the vibration mechanism and the detection system. The signal line is routed to avoid overlapping with the vibration unit, and scanning is performed during periods when vibration is not active, thereby mediating the interaction between these two components and preventing direct interference
Solution Approach 2:
The patent implements periodic scanning during periods when the vibration mechanism is not operating. This timing-based separation ensures that detection occurs when no electric field interference is present, while still maintaining the ability to provide tactile feedback when needed
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 configuration reduces the influence of tactile feedback on contact position detection, allowing for accurate detection of touch sensor positions while providing a tactile sensation.
Implementation Method 1
the touch sensor of the capacitive type forms an electric field on an entire surface of the touch sensor when a weak electrical current is supplied to a transparent conductive film and, by obtaining a change in surface charge at a position contacted by an operator's finger or the like on the conductive film, detects the position
Implementation Method 2
when a tactile sensation providing unit such as, for example, a piezoelectric element is disposed near the touch sensor so as to vibrate the touch sensor, the electric field is generated by a voltage applied for vibrating the piezoelectric element
Data Source
AI summary
A tactile sensation providing apparatus, so as to reduce an influence by provision of a tactile sensation on detection of a position by a touch sensor, includes a touch sensor 11, a tactile sensation providing unit 12 disposed near the sensor 11 and configured to vibrate the sensor 11, a touch sensor control unit 20 configured to transmit a scanning signal to the sensor 11 and, by receiving the signal from the sensor 11, to detect the position of the contact to the sensor, signal lines 16, 18 configured to transmit the signal between the sensor 11 and the control unit 20, and a tactile sensation control unit 30 configured to, based on the position of the contact detected by the control unit 20, control the providing unit 12 to vibrate the sensor 11. The providing unit 12 is disposed avoiding overlapping with the lines 16, 18.