Piezoelectric user interface arrangement, and method for driving piezoelectric elements in a user interface arrangement
Piezoelectric user interface arrangement comprises a voltage converter for controllably generating voltage waveforms driving one or more piezoelectric elements. The voltage converter has a control input. A controller is coupled to said control input to control an output voltage of said voltage converter. The controller has one or more scaling inputs. The controller forms said control signals to make said output voltage follow a target waveform as a function of time. The controller is configured to scale said target waveform on the basis of scaling information received through said one or more scaling inputs.
1 . A piezoelectric user interface system, comprising:
a voltage converter configured to controllably generate voltage waveforms for driving one or more piezoelectric elements, wherein the voltage converter has at least one control input; and
a controller coupled to the at least one control input and configured to control an output voltage of the voltage converter by applying control signals to the at least one control input, wherein the controller has one or more scaling inputs;
wherein the controller is configured to;
form the control signals to make the output voltage follow an original target waveform as a function of time;
determine that the original target waveform cannot be followed; and
in response to determining that the original target waveform cannot be followed, scale the original target waveform based on scaling information received through the one or more scaling inputs so as to allow the output voltage to deviate from the original target waveform and follow the scaled target waveform.
2 . The piezoelectric user interface system according to claim 1 , wherein the controller is configured to scale an amplitude of the original target waveform on the basis of the scaling information.
3 . The piezoelectric user interface system according to claim 1 , wherein the controller is configured to scale a length in time of the original target waveform on the basis of the scaling information.
4 . The piezoelectric user interface system according to claim 1 , wherein the scaling input comprises a configuring input for receiving at least a part of the scaling information in advance as configuration information.
5 . The piezoelectric user interface system according to claim 1 , wherein the scaling input comprises a feedback input for receiving at least a part of the scaling information dynamically as feedback information during the generation of a voltage waveform.
6 . The piezoelectric user interface system according to claim 5 , wherein the feedback input comprises a voltage feedback input for receiving feedback of the output voltage.
7 . The piezoelectric user interface system according to claim 5 , wherein the feedback input comprises a current feedback input for receiving feedback of an output current of the voltage converter.
8 . The piezoelectric user interface system according to claim 1 , wherein the scaling input comprises an internal input for using a quantity internal to the controller as the scaling information.
9 . The piezoelectric user interface system according to claim 1 , wherein:
the voltage converter comprises a boost converter that comprises a power switch for closing and opening a current path through a boost inductor,
the control signals comprise switching pulses to the power switch, and
the controller is configured to change at least one of the duty cycle and the switching frequency of the switching pulses for controlling the output voltage.
10 . A method for operating a piezoelectric user interface system, comprising:
controllably generating, by a voltage converter of the piezoelectric user interface system, voltage waveforms for driving one or more piezoelectric elements, wherein the voltage converter has at least one control input; and
controlling, by a controller of the piezoelectric user interface system coupled to the at least one control input, an output voltage of the voltage converter by applying control signals to the at least one control input, wherein the controller has one or more scaling inputs;
wherein controlling the output signal comprises:
forming, by the controller, the control signals to make the output voltage follow an original target waveform as a function of time;
determining, by the controller, that the original target waveform cannot be followed; and
in response to determining that the original target waveform cannot be followed, scaling, by the controller, the original target waveform based on scaling information received through the one or more scaling inputs so as to allow the output voltage to deviate from the original target waveform and follow the scaled target waveform.