Direct digital drive audio system and method

• US 20050192685A1
• Filed: 05/05/2004
• Published: 09/01/2005
• Est. Priority Date: 02/02/2004
• Status: Active Grant

• Current Assignee: Trimble Navigation Limited (Trimble Inc.)
• Original Assignee: Trimble Navigation Limited (Trimble Inc.)
• Inventors: Puckette, Robert
• Granted Patent: US 7,472,048 B2
• Time in Patent Office: Days
• US Class Current: 700/94
• CPC Class Codes: H04R 1/005 using digitally weighted transducing elements
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones

Abstract

A direct digital drive audio system and method system and method are presented. The direct digital drive system and method utilizes a digital signal to directly drive the speakers. In one exemplary implementation, an audio system includes a sample register, an convergence adjustment component, an accumulated error register, a digital driver and a speaker. The sample register is coupled to the convergence adjustment component which is coupled to the accumulated error register and the digital driver which in turn is coupled to the speaker. The sample register holds an audio sample. The convergence adjustment component calculates the error for each sample. The accumulated error register stores an accumulated error. The digital driver determines whether to drive on a positive digital value, drive on a negative digital value or not drive. The speaker creates audio sounds based upon a signal from the digital driver.

Claims

1. An audio system comprising:

a sample register for holding an audio sample;

a convergence adjustment component for calculating the error for each sample, said convergence adjustment component communicatively coupled to said sample register;

an accumulated error register for storing an accumulated error, said accumulated error register communicatively coupled to said convergence adjustment component;

a driver for driving a digital signal to a speaker, wherein said driver determines whether to drive a positive digital value, drive a negative digital value or not drive a value to said speaker, said driver communicatively coupled to said accumulator error register; and

a speaker for creating audio sounds based upon a signal from said driver, said speaker communicatively coupled to said driver.

2. An audio system of claim 1 wherein said audio sample is a digitized sample of an analog audio signal.

3. An audio system of claim 1 wherein said sample register holds said audio sample for a sample period.

4. An audio system of claim 1 wherein said convergence adjustment component is a free input adder that adds a previous error to a new error and said new error is determined by subtracting the input to the convergence adjustment component from the output of the convergence adjustment component.

5. An audio system of claim 1 wherein said speaker is communicatively coupled between two digital differential outputs permitting both negative and positive differential pulse signals derived by delta-sigma techniques to be applied to the speaker.

6. An audio system of claim 1 wherein said driver includes a first output and a second output wherein:

said first output is driven high and said second output is grounded for a positive logical one drive value;

said second output is driven high and said first output is grounded for a negative logical one drive value; and

said first output and said second output are grounded for a zero logical drive value.

10. An audio method of claim 1 wherein determining said drive status includes utilization of delta-sigma techniques.

11. An audio method of claim 1 wherein said speaker is driven from two digital signals permitting both negative and positive differential signals to be applied to the speaker.

8. An audio method comprising:

obtaining an audio sample;

determining a drive status associated with said audio sample;

driving a speaker cone with a digital signal in accordance with said drive status.

7. An audio system of claim 8 wherein said speaker comprises a first speaker lead and a second speaker lead which are alternatively coupled to said first output and said second output depending upon said cumulative error, and intermediate values are achieved by pulsing said first speaker lead and second speaker lead.

9. An audio method of claim 8 wherein obtaining an audio sample comprises digitizing an analog audio signal.

12. An audio method of claim 8 further comprising:

driving a first output high while a second output is grounded for a positive logical one drive value;

driving said second output high while said first output is grounded for a negative logical one drive value; and

grounding said first output and said second output for a zero logical drive value.

13. An audio method of claim 8 wherein alternatively coupling a first speaker lead and a second speaker lead to said first output and said second output depending upon said cumulative error.

14. An audio method of claim 13 wherein intermediate values are achieved by pulsing said first speaker lead and said second speaker lead.

15. An electronic processing system comprising:

a bus for communicating audio information;

a processor coupled to said bus, said processor for processing said information;

a memory coupled to said bus, said memory for storing said audio information; and

an audio system coupled to said bus, said audio system for creating sounds by driving digital signals directly to a speaker.

16. An electronic processing system of claim 15 wherein said audio system comprises:

a sample register for holding an audio sample;

an convergence adjustment component for calculating the error for each sample, said convergence adjustment component communicatively coupled to said sample register;

an accumulated error register for storing an accumulated error, said accumulated error register communicatively coupled to said convergence adjustment component;

a driver for driving a digital signal to a speaker, wherein said driver determines whether to drive a positive digital value, drive on a negative digital value or not drive a value to said speaker, said driver communicatively coupled to said accumulator error register; and

a speaker for creating audio sounds based upon a signal from said driver, said speaker communicatively coupled to said driver.

17. An electronic processing system of claim 15 wherein said audio sample is a digitized sample of an analog audio signal and said sample register holds said audio sample for a sample period.

18. An electronic processing system of claim 15 wherein said convergence adjustment component is a free input adder that adds a previous error to a new error and said new error is determined by subtracting an input to said adder from an output of said adder.

19. An electronic processing system of claim 15 wherein said driver includes a first output and a second output and:

said first output is driven high and said second output is grounded for a positive logical one drive value;

said second output is driven high and said first output is grounded for a negative logical one drive value; and

said first output and said second output are grounded for a zero logical drive value.

20. An electronic processing system of claim 15 wherein said speaker comprises a first speaker lead and a second speaker lead which are alternatively coupled to said first output and said second output depending upon said cumulative error.