Device and method of monitoring ground connection of moving equipment with insulative bearing arrangement

• US 7,589,537 B1
• Filed: 04/05/2006
• Issued: 09/15/2009
• Est. Priority Date: 04/05/2006
• Status: Expired due to Fees

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Kraz, Vladimir
• Primary Examiner(s): NGUYEN, HOAI AN D
• Application Number:
  US11/400,164
• Time in Patent Office: 1,259 Days
• Field of Search: 324/658, 324/649, 324/600, 324/519, 324/686, 324/538, 324/558, 324/559, 324/500, 324/537, 324/765, 324/662, 324/663, 324/509, 735/143.2, 361/181
• US Class Current: 324/658
• CPC Class Codes: G11B 33/1493 Electro-Magnetic Interference [EMI] or Radio Frequency Interference [RFI] shielding; grounding of static charges
• CPC Class Codes: G11B 5/40 Protective measures on heads, e.g. against excessive temperature G11B5/31 takes precedence; protection against wear G11B5/255 ; protective structure of the head: see under structures, e.g. G11B5/3106

Abstract

A device and method of monitoring ground connection of moving equipment with insulative bearing arrangement is provided that does not use a spring contact that wears out and fails. The device provides a reliable method to monitor the ground connection of the moving equipment with an insulative bearing.

Claims

1. An object, comprising:

a moving member;

a stationary member separated from the moving member by an insulative bearing and electrically connected to the moving member; and

a circuit that measures a parasitic capacitance between the moving member and the stationary member in order to determine a ground connection to the moving member,

wherein the circuit further comprises an output signal whose amplitude changes depending on the grounding connection of the moving member,

wherein the circuit further comprises a rectifier circuit that rectifies the output signal to generate a rectified output signal and a device that compares the amplitude of the rectified output signal and a reference signal to generate a comparator output signal that indicates the grounding connection of the moving member, and

wherein the rectifier circuit further comprises a diode coupled to the output signal, a capacitor and a resistor in parallel, coupled between an output of the diode and ground.

2. An object comprising:

a moving member;

a stationary member separated from the moving member by an insulative bearing and electrically connected to the moving member; and

a circuit that measures a parasitic capacitance between the moving member and the stationary member in order to determine a ground connection to the moving member,

wherein the circuit further comprises an oscillator that generates a signal having a frequency wherein the frequency of the oscillator depends on the connection to the moving member, and

wherein the circuit further comprises a bandpass filter coupled to the oscillator wherein the bandpass filter is tuned to a frequency of the oscillator when a good connection to the moving member exists and an output signal from the bandpass filter is compared to a reference signal to generate a signal indicating a status of the connection to the moving member.

3. An object, comprising:

a moving member;

a stationary member separated from the moving member by an insulative bearing and electrically connected to the moving member; and

a circuit that measures a parasitic capacitance between the moving member and the stationary member in order to determine a ground connection to the moving member,

wherein the circuit further comprises an oscillator that generates a signal having a frequency wherein the frequency of the oscillator depends on the connection to the moving member, and

wherein the circuit further comprises a frequency counter coupled to the oscillator that determines the frequency of the oscillator and generates a signal indicating a status of the connection to the moving member.

4. A device of monitoring the grounding of an object having a moving member and a stationary member separated by an insulative bearing and electrically connected to the moving member, the device comprising:

a circuit that measures a parasitic capacitance between a moving member and a stationary member; and

a ground circuit that indicates a ground connection to the moving member,

wherein the circuit that determines the grounding connection further comprises an output signal whose amplitude changes depending on the grounding connection of the moving member,

wherein the circuit that determines the grounding connection further comprises a rectifier circuit that rectifies the output signal to generate a rectified output signal and a device that compares the rectified output signal and a reference signal to generate a comparator output signal that indicates the grounding connection of the moving member, and

wherein the rectifier circuit further comprises a diode coupled to the output signal, a capacitor and a resistor in parallel, coupled between an output of the diode and ground.

5. A device of monitoring the grounding of an object having a moving member and a stationary member separated by an insulative bearing and electrically connected to the moving member, the device comprising:

a circuit that measures a parasitic capacitance between a moving member and a stationary member; and

a ground circuit that indicates a ground connection to the moving member,

wherein the circuit further comprises an oscillator that generates a signal having a frequency wherein the frequency of the oscillator depends on the connection to the moving member, and

wherein the circuit further comprises a bandpass filter coupled to the oscillator wherein the bandpass filter is tuned to a frequency of the oscillator when a good connection to the moving member exists and an output signal from the bandpass filter is compared to a reference signal to generate a signal indicating a status of the connection to the moving member.

6. A device of monitoring the grounding of an object having a moving member and a stationary member separated by an insulative bearing and electrically connected to the moving member the device comprising:

a circuit that measures a parasitic capacitance between a moving member and a stationary member; and

a ground circuit that indicates a ground connection to the moving member,

wherein the circuit further comprises an oscillator that generates a signal having a frequency wherein the frequency of the oscillator depends on the connection to the moving member, and

wherein the circuit further comprises a frequency counter coupled to the oscillator that determines the frequency of the oscillator and generates a signal indicating a status of the connection to the moving member.

7. A method for monitoring the grounding of an object having a moving member and a stationary member separated by an insulative bearing and electrically connected to the moving member, the method comprising:

measuring a parasitic capacitance between the moving member and the stationary member of the device; and

determining a grounding connection to the moving member based on the measured parasitic capacitance,

wherein determining the ground connection further comprises generating, using an oscillator, a signal having a frequency wherein the frequency of the oscillator depends on the connection to the moving member, and

wherein determining the ground connection further comprises tuning a bandpass filter to a frequency of the oscillator when a good connection to the moving member exists and comparing an output signal from the bandpass filter to a reference signal to generate a signal indicating a status of the connection to the moving member.

8. A method for monitoring the grounding of an object having a moving member and a stationary member separated by an insulative bearing and electrically connected to the moving member, the method comprising:

measuring a parasitic capacitance between the moving member and the stationary member of the device; and

determining a grounding connection to the moving member based on the measured parasitic capacitance,

wherein determining the ground connection further comprises generating, using an oscillator, a signal having a frequency wherein the frequency of the oscillator depends on the connection to the moving member, and

wherein determining the ground connection further comprises using a frequency counter coupled to the oscillator to determine the frequency of the oscillator and generate a signal indicating a status of the connection to the moving member.