Flutter reduction apparatus and method

• US 20060012361A1
• Filed: 07/16/2004
• Published: 01/19/2006
• Est. Priority Date: 07/16/2004
• Status: Active Grant

• Current Assignee: Auto Meter Products Incorporated
• Original Assignee: Auto Meter Products Incorporated
• Inventors: Schubert, Thomas A.
• Granted Patent: US 7,230,418 B2
• Time in Patent Office: Days
• US Class Current: 324/160
• CPC Class Codes: G01P 1/04 Special adaptations of driving means
• CPC Class Codes: G01P 1/07 Indicating devices, e.g. for remote indication indicating working conditions of vehicles G07C5/00
• CPC Class Codes: G01P 3/44 for measuring angular speed G01P3/56 takes precedence

Abstract

A tachometer circuit including a flutter reduction circuit and a tachometer is described. The tachometer circuit cancels pointer flutter in the tachometer without adversely affecting pointer response.

Claims

1. A tachometer circuit comprising:

a tachometer; and

a flutter reduction circuit electrically coupled to and driving said tachometer, said flutter reduction circuit generating a voltage to cancel ripple voltages.

2. The tachometer circuit of claim 1, wherein the input signals comprise pulses from an engine.

3. The tachometer circuit of claim 1, wherein said flutter reduction circuit comprises:

a high pass filter circuit; and

a tachometer driver circuit electrically coupled to said high pass filter circuit, said high pass filter circuit filtering the unwanted input voltages and generating the voltage to cancel ripple voltages.

4. The tachometer circuit of claim 3, wherein said high pass filter circuit further comprises:

an operational amplifier; and

a voltage divider electrically coupled to said operational amplifier.

5. The tachometer circuit of claim 4, wherein said voltage divider further comprises two resistors in connected series.

6. The tachometer circuit of claim 4, wherein said operational amplifier outputs the voltage that is used to cancel rippled voltages.

7. The tachometer circuit of claim 4, wherein said operational amplifier is biased by a bias signal from said driver integrated circuit.

8. A flutter reduction circuit for use with a tachometer, said flutter reduction circuit comprising:

a high pass filter circuit; and

a driver circuit electrically coupled to said high pass filter circuit, said high pass filter circuit passing unwanted input signals to a first circuit within the driver adapted to cancel out the signals and said high pass filter circuit generating a voltage to cancel ripple voltages.

9. The flutter reduction circuit of claim 8, wherein said high pass filter circuit further comprises:

an operational amplifier; and

a voltage divider electrically coupled to said operational amplifier.

10. The flutter reduction circuit of claim 9, wherein said voltage divider further comprises two resistors in connected series.

11. The flutter reduction circuit of claim 9, wherein said operational amplifier outputs the voltage that is used to cancel rippled voltages.

12. The flutter reduction circuit of claim 9, wherein said operational amplifier is biased by a bias signal from said driver integrated circuit.

13. The flutter reduction circuit of claim 8 wherein the input signals comprise pulses from an engine.

14. A tachometer circuit comprising:

means for inputting a pulsed ignition signal;

means for converting the pulsed ignition signal to a voltage;

means for converting the voltage into a first signal; and

means for canceling pointer flutter in a tachometer using the first signal.

15. A method of operating a tachometer circuit, said method comprising:

inputting a pulsed ignition signal;

converting the pulsed ignition signal to a voltage;

converting the voltage into a first signal; and

canceling pointer flutter in a tachometer using the first signal.

16. The method of claim 15 further comprising the act of filtering unwanted voltages based on a frequency of the ignition signal.