Transducer driver
A circuit for driving a transducer in a mid-air haptic system includes a voltage source, a voltage sink, a current source, a trickle capacitor, a storage capacitor, a haptic system transducer, a first switch, a second switch, and a third switch. Using these components, a portion of the charge required for switching a transducer is sourced from the decoupling capacitance. When the switching completes, additional charge is transferred immediately from the power supply back into the decoupling capacitance. This acts to lower the peak current by fully utilizing 100% of a switching waveform for transfer of charge from the power supply to capacitors local to the transducer.
1. A circuit comprising:
a voltage source;
a voltage sink;
a current source having a current source first end and a current source second end;
a trickle capacitor having a trickle capacitor first end and a trickle capacitor second end;
a storage capacitor having a storage capacitor first end and a storage capacitor second end;
a haptic system transducer having a transducer first end and a transducer second end;
a first switch having a first switch first end and a first switch second end;
a second switch having a second switch first end and a second switch second end;
a third switch having a third switch first end and a third switch second end;
wherein the current source first end is connected to the voltage source;
wherein the current source second end is connected to the trickle capacitor first end and is connected to the first switch first end;
wherein the first switch second end is connected to the third switch first end and is connected to the second switch first end and is connected to the transducer first end;
wherein the third switch second end is connected to the storage capacitor first end; and
wherein the second switch second end, the transducer second end, the storage capacitor second end and the trickle capacitor second end are connected to the voltage sink.
2. The circuit as in claim 1 wherein the current source, the first switch, the second switch and the third switch are located on an integrated circuit.
3. The circuit as in claim 2 , wherein the voltage source, the voltage sink, the transducer, the storage capacitor, and the trickle capacitor are discrete components.
4. The circuit as in claim 2 , wherein the storage capacitor and the trickle capacitor are located on the integrated circuit.
5. The circuit as in claim 2 , wherein when the first switch is closed, charge accumulated on the trickle capacitor is transferred onto the transducer.
6. The circuit as in claim 2 , wherein when the first switch is open the current from the current source flows into the trickle capacitor charging the capacitor towards the amount of the voltage source.
7. The circuit as in claim 2 , wherein when the second switch is closed the charge on the transducer is discharged into the voltage sink.
8. The circuit as in claim 2 , wherein when the second switch is open the transducer is prevented from discharging into the voltage sink.
9. A circuit comprising:
a voltage source;
a voltage sink;
a current source having a current source first end and a current source second end;
a trickle capacitor having a trickle capacitor first end and a trickle capacitor second end;
a first storage capacitor having a first storage capacitor first end and a first storage capacitor second end;
a first haptic system transducer having a first transducer first end and a first transducer second end;
a first switch having a first switch first end and a first switch second end;
a second switch having a second switch first end and a second switch second end;
a third switch having a third switch first end and a third switch second end;
a second storage capacitor having a second storage capacitor first end and a second storage capacitor second end;
a second haptic system transducer having a second transducer first end and a second transducer second end;
a fourth switch having a fourth switch first end and a fourth switch second end;
a fifth switch having a fifth switch first end and a fifth switch second end;
a sixth switch having a sixth switch first end and a sixth switch second end;
wherein the first current source first end is connected to the voltage source;
wherein the first current source second end is connected to the trickle capacitor first end and is connected to the first switch first end, and is connected to the fourth switch first end;
wherein the first switch second end is connected to the third switch first end and is connected to the second switch first end and is connected to the first transducer first end;
wherein the fourth switch second end is connected to the sixth switch first end and is connected to the fifth switch first end and is connected to the second transducer first end;
wherein the third switch second end is connected to the first storage capacitor first end;
wherein the sixth switch second end is connected to the second storage capacitor first end;
wherein the second switch second end, the fifth switch second end, the first transducer second end, the second transducer second end, the first storage capacitor second end, the second storage capacitor second end, and the trickle capacitor second end are connected to the voltage sink.
10. The circuit as in claim 9 wherein the current source, the first switch, the second switch, the third switch, the fourth switch, the fifth switch and the sixth switch are located on an integrated circuit.
11. The circuit as in claim 8 , wherein when the first switch and the fourth switch are closed charge accumulated on the trickle capacitor is transferred onto the first transducer and second transducer.
12. The circuit as in claim 8 , wherein the first switch and the fourth switch are open, the current from the current source flows into the trickle capacitor.
13. The circuit as in claim 8 , wherein the second switch and the fifth switch are closed, the charge on the first transducer and the second transducer is discharged into the voltage sink.
14. The circuit as in claim 8 , wherein the second switch and the fifth switch are open, the first transducer and the second transducer are prevented from discharging into the voltage sink.
15. A circuit comprising:
a voltage source;
a voltage sink;
a current source having a current source first end and a current source second end;
a trickle capacitor having a trickle capacitor first end and a trickle capacitor second end;
a storage capacitor having a storage capacitor first end and a storage capacitor second end;
a haptic system transducer having a transducer first end and a transducer second end;
a first switch having a first switch first end and a first switch second end;
a second switch having a second switch first end and a second switch second end;
a third switch having a third switch first end and a third switch second end;
a first Zener diode having a first anode and a first cathode;
a second Zener diode having a second anode and a second cathode;
wherein the current source first end is connected to the voltage source;
wherein the current source second end is connected to the trickle capacitor first end and is connected to the first switch first end and is connected to the first cathode;
wherein the first switch second end is connected to the third switch first end and is connected to the second switch first end and is connected to the second cathode and is connected to the transducer first end;
wherein the third switch second end is connected to the storage capacitor first end; and
wherein the second switch second end, the transducer second end, the storage capacitor second end, the first anode, the second anode and the trickle capacitor second end are connected to the voltage sink.
16. The circuit as in claim 15 , wherein when the first switch is closed, charge accumulated on the trickle capacitor is transferred onto the transducer.
17. The circuit as in claim 16 , wherein when the first switch is closed, current from the current source is also provided to the trickle capacitor and the transducer.
18. The circuit as in claim 15 , wherein when the first switch is open the current from the current source flows into the trickle capacitor.
19. The circuit as in claim 15 , wherein when the second switch is closed, the charge on the transducer is discharged into the ground sink.
20. The circuit as in claim 15 , wherein when the second switch is open, the transducer is prevented from discharging into the ground sink.