Vibrotactile Driver Circuit Using Bipolar AC Sources
Solution Overview
Problem
Conventional driver circuits for vibrotactile actuators in haptic devices are unipolar and generate potentially dangerous 200V peak-to-peak voltage, making it difficult to build integrated circuits that can safely drive such high voltages and posing safety risks to users.
Innovation Solution
A driver circuit configuration using two AC voltage sources, one positive and one negative, 180 degrees out of phase, with a capacitive element and regulating element to generate a peak-to-peak voltage greater than 200V, allowing for safer and more efficient operation of vibrotactile actuators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional unipolar driver circuit is used to generate 200V peak-to-peak voltage for vibrotactile actuators, then the haptic feedback performance is achieved, but the safety risk to users increases due to potentially dangerous high voltage exposure
Solution Approach 1:
The driver circuit is segmented into two separate AC voltage sources (first and second AC voltage sources) operating at different phase angles, rather than using a single unipolar voltage source. This segmentation allows the circuit to generate the required peak-to-peak voltage while maintaining lower instantaneous voltage levels, reducing safety risks to users.
Solution Approach 2:
The circuit employs two AC voltage sources operating at different phase angles (e.g., 0 degrees and 60 degrees) to create a periodic voltage waveform. This periodic action with phase shifting enables the generation of high peak-to-peak voltage across the actuator while keeping individual voltage sources at safer levels, thus resolving the safety contradiction.
2Device complexity
If an integrated circuit is used to reduce size and cost of the driver circuit, then the device compactness and cost are improved, but the manufacturing complexity increases substantially for circuits capable of driving 200V
Solution Approach 1:
The driver circuit is divided into multiple separate AC voltage sources and control circuits operating at lower voltages, rather than requiring a single integrated circuit capable of 200V operation. This segmentation allows each component to be manufactured using standard low-voltage IC processes, avoiding the substantial manufacturing complexity associated with high-voltage integrated circuits.
Solution Approach 2:
The patent introduces phase-shifting circuitry and voltage combination networks as intermediary elements that enable the synthesis of high peak-to-peak voltage from multiple lower-voltage AC sources. These intermediaries allow the system to achieve high-voltage functionality without requiring high-voltage integrated circuit fabrication.
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 provides a safer and more efficient means to generate haptic feedback, enabling a more immersive experience in virtual reality systems while reducing the risk of electrical hazards associated with high voltage.
Implementation Method 1
The first AC voltage source is 180 degrees out of phase with the second AC voltage source. In embodiments where the first AC voltage source and the second AC voltage source have a same peak-to-peak voltage of (|Vmax|), the configuration of the driver circuit is such that the peak-to-peak voltage as seen by the vibrotactile actuator is greater than |Vmax|.
Data Source
AI summary
A haptic device comprises a wearable material configured to a portion of a user. A vibrotactile actuator is coupled to the wearable material and provides haptic feedback in accordance with a drive signal. A driver circuit is electrically coupled to the vibrotactile actuator and provides the drive signal to the vibrotactile actuator. The driver circuit includes an alternating current (AC) voltage source assembly that has a first AC voltage source and a second AC voltage source, each having a terminal. The terminal of the first AC voltage source is electrically coupled to the vibrotactile actuator. A capacitive element electrically is coupled to the terminal of the negative AC voltage source and a regulating element. The regulating element includes a first coupling point and a second coupling point. The first coupling point is electrically coupled to the capacitive element and the vibrotactile actuator, and the second coupling point is grounded.