Piezoelectric sensor, and an electrical appliance, an installation or a gadget comprising at least one piezoelectric sensor

1. A piezoelectric sensor ( 2 ), comprising:

at least one piezoelectric sensor element ( 20 ) having at least two terminals (CON 2 - 1 , CON 2 - 2 ); and

a microcontroller ( 26 ) electrically connected to said at least one piezoelectric sensor element ( 20 ) and configured to read a signal (PZF 1 -VREF) indicative of a voltage (PZCOM-PZ 1 ) between the at least two terminals (CON 2 - 1 , CON 2 - 2 ), and to output at least one output signal (INTERRUPT, BUZZER, DRVEN 1 , HVEN, LED 1 , LED 2 , LED 3 , DRVP, DRVN) in response to the signal (PZF 1 -VREF) read, indicating that the piezoelectric sensor element ( 20 ) is being pressed or has been pressed by a finger;

and wherein;

the microcontroller ( 26 ) comprises at least one two or more dimensional sensitivity threshold register ( 30 ) containing at least one sensitivity threshold;

the microcontroller ( 26 ) is configured to evaluate the signal (PZF 1 -VREF) indicative of the voltage (PZCOM-PZ 1 ) depending on the sensitivity threshold, in consequence of which a sensitivity of the piezoelectric sensor ( 20 ) is defined;

and wherein: the microcontroller ( 26 ) is configured, in response to receiving at least one sensitivity threshold command from a host ( 28 ) over a serial data bus ( 27 ), to set or to adjust the sensitivity threshold in the at least one two or more dimensional sensitivity threshold register ( 30 ), wherein the serial data bus ( 27 ) for receiving sensitivity threshold commands is one of an I 2 C data bus or an SPI data bus, and whereby the microcontroller ( 26 ) is adapted:

i) after receiving the sensitivity threshold command, to continue using the at least one actual sensitivity threshold until the sensitivity threshold command has been completely processed and the at least one two or more dimensional sensitivity threshold register ( 30 ) has been updated by the microcontroller ( 26 ), and then to swap to using the updated at least one two or more dimensional sensitivity threshold register ( 30 ) with the adjusted sensitivity thresholds; or:

ii) after receiving the sensitivity threshold command, to discard any signals from all piezoelectric sensor elements ( 20 ) or at least from such piezoelectric sensor elements ( 20 ), to the sensitivity threshold of which the sensitivity threshold command relates, until the microcontroller ( 26 ) has completely processed the sensitivity threshold command and updated the at least one two or more dimensional sensitivity threshold register ( 30 );

wherein the at least one two or more dimensional sensitivity threshold register ( 30 ) comprises one or more sensitivity threshold values ( 100 ), each of which is a function of the magnitude of the voltage (PZCOM-PZ 1 ), the length of the voltage (PZCOM-PZ 1 ) window, and/or the number of voltage (PZCOM-PZ 1 ) sequences that are required to accept signal (PZF 1 -VREF) from a piezoelectric sensor element ( 20 ) as a user input;

wherein the plurality of sensitivity threshold values ( 100 ) is stored in a two-dimensional matrix in said at least one two or more dimensional sensitivity threshold register ( 30 ); and

wherein the microcontroller ( 26 ) is configured to change said sensitivity threshold values ( 100 ) stored in said two-dimensional matrix in a given row or column of said two-dimensional matrix in response to receiving the sensitivity threshold command ( 105 , 106 , 107 ).

2. The piezoelectric sensor ( 2 ) according to claim 1 , wherein: the piezoelectric sensor ( 2 ) comprises a plurality of piezoelectric sensor elements ( 20 ) and the at least one two or more dimensional sensitivity threshold register ( 30 ) comprises a plurality of sensitivity threshold values ( 100 ) each defining a sensitivity threshold; and wherein: in the microcontroller ( 26 ), each of the sensitivity thresholds is associated to a particular piezoelectric sensor element ( 20 ) or to a group of piezoelectric sensor elements ( 20 ).

3. The piezoelectric sensor ( 2 ) according to claim 2 , wherein: the microcontroller ( 26 ) is configured to adjust or to set sensitivity threshold values ( 100 ) for a plurality of piezoelectric sensor elements ( 20 ) individually in response to receiving the sensitivity threshold command.

4. The piezoelectric sensor ( 2 ) according to claim 1 , further comprising:

one or more signalling devices ( 24 , 20 , 22 ), responsive to said microcontroller ( 26 ), and configured to acoustically, haptically and/or optically signal that the pressing on the at least one piezoelectric sensor element ( 20 ) by the finger has exceeded a sensitivity threshold, is below a sensitivity threshold, or matches with a sensitivity threshold;

and wherein: the microcontroller ( 26 ) further comprises at least one signalling register and is configured, in response to receiving at least one signalling register command from the host ( 28 ) over the serial data bus ( 27 ), to set or adjust the at least one signalling register;

and wherein: the microcontroller ( 26 ) is configured to change an operating pattern according to which one of the one or more signalling devices are activated depending on the contents of the at least one signalling register.

5. The piezoelectric sensor ( 2 ) according to claim 4 , wherein: the signalling devices ( 24 , 20 , 22 ) are selected from the group of signaling devices consisting of a loudspeaker ( 22 ), a buzzer ( 24 ), any of the at least one piezoelectric sensor element(s) ( 20 ) of the piezoelectric sensor ( 2 ), and a lamp, in particular an LED ( 22 ).

6. The piezoelectric sensor ( 2 ) according to claim 4 , wherein: the microcontroller ( 26 ) is configured to use the piezoelectric sensor element ( 20 ) as the signaling device ( 20 ) on which the pressing by the finger is being detected or has been detected, to give tactile feedback by switching on and off a signal (Haptic on 1 , Haptic on 2 , Boost on, Drive) to be emitted through the piezoelectric sensor element ( 20 ).

7. The piezoelectric sensor ( 2 ) according to claim 4 , wherein: the sensitivity threshold command is transmitted in a signaling register command or vice versa.

8. The piezoelectric sensor ( 2 ) according to claim 4 , wherein: the microcontroller ( 26 ) is configured to switch on a signal (Haptic on 1 , Haptic on 2 , Boost on, Drive) to be emitted through the at least one piezoelectric sensor element ( 20 ), and during the piezoelectric emitting the signal, to switch off the signal (Haptic on 1 , Haptic on 2 , Boost on, Drive) and to measure the voltage (PZF 1 -VREF) indicative of the voltage (PZCOM-PZ 1 ) between the two terminals (CON 2 - 1 , CON 2 - 2 ) of the same at least one piezoelectric sensor element ( 20 ), and to use the measured voltage (PZF 1 -VREF) for self-calibration of the piezoelectric sensor ( 2 ).

9. The piezoelectric sensor ( 2 ) according to claim 1 , wherein: the microcontroller ( 26 ) is configured to:

use at least two sensitivity levels for interpretation of the signal (PZF 1 -VREF) indicative of the voltage (PZCOM-PZ 1 ) between the two terminals (CON 2 - 1 , CON 2 - 2 ) of the at least one piezoelectric sensor element ( 20 ) during one touch interaction; and/or

apply at least one relation stored in the microcontroller ( 26 ) to select a relation between the signal (PZF 1 -VREF) indicative of the voltage (PZCOM-PZ 1 ) between the two terminals (CON 2 - 1 , CON 2 - 2 ) of the at least one piezoelectric sensor element ( 20 ) and driving of the at least one signalling device ( 24 , 20 , 22 ) during the touch interaction.

10. An electrical appliance, an installation or a gadget ( 1 ) according to claim 1 comprising:

a host ( 28 )

a device surface ( 10 ); and

at least one piezoelectric sensor ( 2 ) according to claim 1 , arranged below the device surface ( 10 ) in such a manner that, and wherein said device surface is configured such that when the device surface ( 10 ) is being pressed with a finger, the at least one piezoelectric sensor element ( 20 ) of the piezoelectric sensor ( 2 ) proximate said device surface that is being pressed with a finger is bent, generating a voltage (V) over the at least one piezo electric sensor element ( 20 ), and connected to the host ( 28 ) via a serial data bus ( 27 );

and wherein:

the host ( 28 ) is configured to use at least one output signal (INTERRUPT, BUZZER, DRVEN 1 , DRVP, DRVN) transmitted to the host ( 28 ) from the microcontroller ( 26 ) over the serial data bus ( 27 ) as user input to the appliance, the installation or the gadget ( 1 ).

11. The electrical appliance, installation or gadget according to claim 10 , wherein:

the piezoelectric sensor ( 2 ) further comprises:

at least one signalling device ( 24 , 20 , 22 ) configured to acoustically, haptically and/or optically signal that the pressing on a piezoelectric sensor element ( 20 ) by the finger has exceeded a sensitivity threshold, is below a sensitivity threshold, or matches with a sensitivity threshold;

and wherein: the microcontroller ( 26 ) further comprises at least one signalling register and is configured, in response to receiving at least one signalling register command from the host ( 28 ) over the serial data bus ( 27 ), to set or adjust the at least one signalling register;

and wherein: the microcontroller ( 26 ) is configured to change an operating pattern according to which of the at least one signalling devices are used depending on the contents of the at least one signalling register;

and wherein the electrical appliance, the installation or the gadget ( 2 ) is configured to use the at least one signalling device ( 24 , 20 , 22 ) acoustically, haptically and/or optically to signal to that user input has been entered.

12. The electrical appliance, installation or gadget according to claim 11 , wherein: the electrical appliance, the installation or the host ( 28 ) is configured to command the microcontroller ( 26 ) to set or to adjust the sensitivity threshold between two consequent user inputs.

13. The electrical appliance, installation or gadget according to claim 10 , wherein: the electrical appliance, the installation or the gadget ( 1 ) is configured to adjust or set the sensitivity threshold for at least one piezoelectric sensor element ( 20 ) of the piezoelectric sensor ( 2 ) between the function of a touch switch and a force meter which detects a discrete number of force magnitudes.

14. The electrical appliance, installation or gadget ( 1 ) according to claim 10 , wherein:

the piezoelectric sensor element ( 20 ) is also configured to produce a signal to the at least one piezoelectric sensor element ( 20 ) to make it vibrate;

and wherein:

the electrical appliance, installation or gadget ( 1 ) is configured to calibrate the sensitivity of the at least one piezoelectric sensor element ( 20 ) by i) producing a test signal to the at least one piezoelectric sensor element ( 20 ) and ii) comparing the signal (PZF 1 -VREF) indicative of the voltage (PZCOM-PZ 1 ) of the at least one piezoelectric sensor element ( 20 ) caused by the test signal, and iii) setting or adjusting the sensitivity threshold so that the at least one piezoelectric sensor element ( 20 ) produces a user input as a response to the test signal.