Single Wire Haptic Driver Circuit with Automatic Mode Switching
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Solution Overview
Problem
Existing haptic driver circuits require complex configurations and consume significant power due to the need for manual characterization and multiple control interfaces, which complicates the generation of discernible haptic signals and efficient power management in battery-powered devices.
Innovation Solution
A haptic driver circuit that employs a single input control signal for actuation and braking, transitioning between open and closed loop control modes automatically, and includes a timer for low power mode activation, allowing for efficient power conservation and simplified host device control through a single wire interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple control interfaces and manual characterization are used, then haptic actuator control capability is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent implements a single control interface that performs multiple functions: it controls both actuation and braking operations, selects between open-loop and closed-loop modes, and manages waveform playback without requiring separate digital interfaces. This universal interface reduces pin count and simplifies host device connectivity while maintaining full haptic control capability
Solution Approach 2:
The driver circuit automatically performs resonance tracking and mode selection without requiring manual characterization or host device configuration. The system self-adjusts control parameters based on real-time feedback, eliminating the need for complex pre-characterization procedures and reducing the burden on the host device
2Speed
If closed loop feedback control is used, then haptic actuator response time is improved, but power consumption increases
Solution Approach 1:
The patent dynamically switches between open-loop and closed-loop control modes based on operational requirements. During actuation phases, open-loop control is used for power efficiency, while closed-loop feedback is engaged during braking operations where precise control is critical. This dynamic adaptation optimizes the trade-off between response time and power consumption
Solution Approach 2:
The system employs periodic sampling of the haptic actuator state through the single control interface, enabling feedback control only when necessary rather than continuous monitoring. This periodic action reduces power consumption while maintaining adequate control responsiveness
3Adaptability or versatility
If waveform libraries and digital interfaces are used, then haptic effect variety is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts the waveform generation and storage functions from the host device and integrates them directly into the haptic driver circuit. Internal waveform generators provide multiple haptic effects without requiring external digital interfaces or host device memory, reducing both power consumption and system complexity while maintaining effect variety
Data Source
AI summary
Disclosed examples include methods and circuits to drive a haptic actuator, in which a single input signal from a host device has a first state representing a command to drive the actuator and a second state representing a command to stop the actuator. A control circuit provides a drive control signal to a driver circuit to drive the haptic actuator in response to the control signal transitioning to the first state, and to stop the haptic actuator in response to the control signal transitioning to the second state. A timer circuit places the circuit in a low power mode a predetermined time after the control signal transitions to the second state, or the control circuit places the circuit in the low power mode in response to a feedback signal indicating that the actuator has reached a stopped condition.