Drivers for Capacitive Loads

A technology of capacitors and drivers, applied in the direction of using vibrating fluids, generators/motors, piezoelectric effects/electrostrictive or magnetostrictive motors, etc., can solve problems such as expensive technology
CN104335475BActive Publication Date: 2018-07-10TEXAS INSTR INC
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
TEXAS INSTR INC
Publication Date
2018-07-10

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Abstract

The present invention provides a device (100) and method for driving a piezoelectric transducer (PZT). The H-bridge (116) includes switches (S1-S4), and the H-bridge (116) is coupled to the inductor L through terminals SWP and SWM and it functions as a buck-boost circuit (110). The control circuit (118) receives a control signal from the main processor (103) indicating the desired power output and frequency of PZT recovery (104). Based on current and / or voltage sensing from the buck-boost circuit terminals (SWP, SWM, BST), the control circuit (118) generates a pulse width modulated (PWM) signal, which is used to control the switches (S1- S4) Thus enabling the buck-boost circuit (110) to provide the charge on capacitor C from the battery (101) coupled to the H-bridge (116) at the appropriate time.
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Description

technical field

[0001] The present invention relates generally to drivers for capacitive loads, and more particularly to drivers configured to drive piezoelectric transducers in the audio frequency band. Background technique

[0002] In many applications, increased robustness and reduced cost are desired. One application with this desire is mobile space devices, this approach is twofold, reducing cost and increasing robustness, that is, changing the human-machine interaction part of mobile devices by separating speaker and haptic functions. To achieve this goal, piezoelectric transducers can be affixed to the screen to vibrate the screen, allowing the screen to act as a speaker or a touchscreen with tactile feedback (eg, vibration feedback indicating a key touch).

[0003] One problem, however, is that piezoelectric transducers are typically high capacitive loads (eg, 1 μF) and it is difficult to drive these transducers with sufficient mass to act as speakers and with suffi...

Claims

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