DRIVERS AND METHODS FOR DRIVING A LOAD

• US 20090003628A1
• Filed: 07/28/2008
• Published: 01/01/2009
• Est. Priority Date: 01/26/2007
• Status: Active Grant

• Current Assignee: Chartoleaux KG LLC (Intellectual Ventures LLC), JM Electronics Ltd LLC (Intellectual Ventures LLC)
• Original Assignee: JM Electronics Ltd LLC (Intellectual Ventures LLC)
• Inventors: Kirn, Larry
• Granted Patent: US 8,538,040 B2
• Time in Patent Office: Days
• US Class Current: 381/96
• CPC Class Codes: H04R 3/007 Protection circuits for transducers

Abstract

Embodiments of the present invention provide methods and devices for controlling a command signal applied to a load. In embodiments of the invention, current through and voltage across a load are determined and the values of both are used to generate a hybrid control signal. For example, in some embodiments the hybrid control signal is generated by taking a weighted summation of the current and voltage control signals. In other embodiments, a percentage of the difference between the current and voltage control signals is added to one of the current or voltage control signals to generate the hybrid control signal. In one embodiment, a potentiometer is used to generate the hybrid control signal.

Claims

1. A method of driving a load with an amplifier, the method comprising:

applying a command voltage to the load;

generating a voltage control signal representative of a voltage across the load;

generating a current control signal representative of a current through the load;

combining the voltage control signal and the current control signal to generate a hybrid control signal; and

adjusting the command voltage based on the hybrid control signal.

2. The method of claim 1, further comprising, prior to said combining, manipulating the current control signal in response to detecting a peak in the command voltage to the load.

3. The method of claim 2, wherein said manipulating the current control signal comprises attenuating the current control signal.

4. The method of claim 2, wherein said manipulating the current control signal comprises filtering the current control signal.

5. The method of claim 1, further comprising, prior to said combining, manipulating the voltage control signal in response to detecting a peak in the command voltage to the load.

6. The method of claim 1, wherein said combining comprises taking a weighted summation of the current control signal and the voltage control signal.

7. The method of claim 1, wherein said combining comprises generating the hybrid control signal having a value between the current control signal and the voltage control signal.

8. The method of claim 6, wherein said combining comprises calculating a difference between the current control signal and the voltage control signal and adding a percentage of the difference to one of the current control signal or the voltage control signal.

9. The method of claim 8, wherein said combining further comprises:

applying the voltage control signal and the current control signal to a potentiometer having a wiper; and

setting the wiper based on the percentage.

10. The method of claim 9, wherein the percentage changes over time, and wherein the wiper setting changes as the percentage changes.

11. The method of claim 8, wherein the load has expected impedance characteristics, and wherein the percentage is chosen according to the expected impedance characteristics.

12. The method of claim 8, wherein the percentage is 70.7 percent, and wherein the percentage is added to the voltage control signal to achieve constant power operation.

13. The method of claim 1, wherein the voltage control signal and the current control signal are both voltages, and wherein said combining comprises applying both the voltage control signal and the current control signal to a voltage divider.

14. The method of claim 1, wherein the load comprises a loudspeaker.

15. A method of improving bass performance of a loudspeaker receiving audio input, the method comprising:

determining a threshold frequency below which to apply hybrid control; and

controlling operation of an amplifier driving the loudspeaker for frequencies at or below the threshold frequency, wherein said controlling comprises;

applying a command voltage to the loudspeaker;

generating a voltage control signal representative of a voltage across the loudspeaker;

generating a current control signal representative of a current through the loudspeaker;

combining the voltage control signal and the current control signal to generate a hybrid control signal; and

adjusting the command voltage based on the hybrid control signal.

16. The method of claim 15, wherein the threshold frequency is 2 kHz.

17. The method of claim 15, wherein the threshold frequency is above 100 Hz.

18. A driver for driving a load, the driver comprising:

an amplifier configured to apply a command signal to the load;

a voltage sensor configured to generate a voltage control signal indicative of a voltage across the load;

a current sensor configured to generate a current control signal indicative of a current through the load;

a controller having a first input terminal, a second input terminal, and an output terminal, wherein the controller is configured to;

receive the voltage control signal at the first input terminal;

receive the current control signal at the second input terminal; and

generate a hybrid control signal at the output terminal based on both the voltage control signal and the current control signal; and

a feedback device configured to receive the hybrid control signal and configured to modify the command signal based on the hybrid control signal.

19. The driver of claim 18, further comprising:

a first manipulator coupled between the voltage sensor and the controller; and

a second manipulator coupled between the current sensor and the controller;

wherein the first and second manipulators are configured to manipulate the voltage and current control signals, respectively, in response to detecting a peak in the command signal.

20. The driver of claim 19, wherein the second manipulator is configured to attenuate the current control signal.

21. The driver of claim 19, wherein the second manipulator is configured to filter the current control signal.

22. The driver of claim 19, wherein the first manipulator is configured to attenuate the voltage control signal.

23. The driver of claim 19, wherein the first manipulator is configured to filter the voltage control signal.

24. The driver of claim 18, wherein the voltage sensor comprises a second amplifier having a first input terminal, a second input terminal, and an output terminal, wherein the first and second input terminals are configured to measure a voltage across the load, and wherein the output terminal of the second amplifier is coupled to the first input terminal of the controller.

25. The driver of claim 18, wherein the current sensor comprises:

a resistive element configured to couple between the load and a reference voltage so that a voltage across the resistive element will be indicative of a current through the load; and

a third amplifier having a first input terminal, a second input terminal, and an output terminal, wherein the first and second input terminals of the third amplifier are configured to measure a voltage across the resistive element, and wherein the output terminal of the third amplifier is coupled to the second input terminal of the controller to deliver the current control signal indicative of the current through the load.

26. The driver of claim 25, wherein the reference voltage is a ground.

27. The driver of claim 18, wherein the controller comprises a voltage divider having a first input terminal, a second input terminal, and an output terminal, wherein the voltage divider further comprises a first resistive element between the first input terminal and the output terminal and a second resistive element between the second input terminal and the output terminal, wherein the voltage divider is configured to generate the hybrid control signal at the output terminal, and wherein the hybrid control signal is a voltage between the voltage control signal and the current control signal.

28. The driver of claim 27, wherein the hybrid control signal represents the sum of:

a percentage of a difference between the voltage control signal and the current control signal; and

one of the current control signal or the voltage control signal.

29. The driver of claim 28, wherein the percentage is 70.7%, and wherein the percentage of the difference is added to the voltage control signal for constant power operation.

30. The driver of claim 28, wherein the voltage divider further comprises a potentiometer having a wiper, and wherein the percentage is set by the wiper.

31. The driver of claim 18, wherein the load comprises a loudspeaker.

32. An audio system, the system comprising:

a loudspeaker; and

a driver comprising;

an amplifier configured to apply a command signal to the loudspeaker;

a voltage sensor configured to generate a voltage control signal indicative of a voltage across the loudspeaker;

a current sensor configured to generate a current control signal indicative of a current through the loudspeaker;

a controller having a first input terminal, a second input terminal, and an output terminal, wherein the controller is configured to;

receive the voltage control signal at the first input terminal;

receive the current control signal at the second input terminal; and

generate a hybrid control signal at the output terminal as a function of both the current control signal and the voltage control signal; and

a feedback device configured to receive the hybrid control signal and configured to modify the command signal based on the hybrid control signal.