FAST RESPONSE CAPACITIVE GAUGING SYSTEM FEATURING STEEP SLOPE FILTER DISCRIMINATION CIRCUIT
First Claim
Patent Images
1. A capacitive sensing system for measuring the height of a laser head above a plastic work piece, said system comprising:
- a laser head nozzle forming a first plate of a capacitor;
the plastic work piece forming a dielectric portion of the capacitor;
a capacitive-responsive radio frequency oscillator operably coupled to the capacitor, said oscillator providing an output; and
a high-frequency, high-order bypass filter to process the output from the oscillator to measure minute changes in capacitance of the capacitor.
1 Assignment
0 Petitions
Accused Products
Abstract
The high speed, high accuracy capacitive gauging system employs an oscillator fed through steep slope filter that is discriminates between very small changes in capacitance even in the presence of electrical noise. During intervals when the probe tip is retracted, the oscillator frequency is calibrated to match the sweet spot in the center of the linear operative region of the steep slope filter. This calibrates the system to overcome the effects of varying temperature and humidity in the manufacturing environment.
-
Citations
20 Claims
-
1. A capacitive sensing system for measuring the height of a laser head above a plastic work piece, said system comprising:
-
a laser head nozzle forming a first plate of a capacitor;
the plastic work piece forming a dielectric portion of the capacitor;a capacitive-responsive radio frequency oscillator operably coupled to the capacitor, said oscillator providing an output; and a high-frequency, high-order bypass filter to process the output from the oscillator to measure minute changes in capacitance of the capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A sensing system for a laser, the system comprising:
-
a laser having a nozzle; an actuation mechanism coupled to the nozzle; a capacitive sensing system comprising a capacitor formed of the nozzle and a polymer work piece; a capacitive response oscillator operably coupled to the capacitive sensing system, said capacitive response oscillator varying from a first radio frequency to a second radio frequency in response to changes in capacitance of the capacitive sensing system; a high-order bypass filter to process an output signal from the capacitive response oscillator, said high-order bypass filter being a greater than 4th order bypass filter; and a radio frequency detector configured to convert a varying output of the filter into a varying voltage, wherein said actuator mechanism is operably coupled to the radio frequency detector to move the nozzle in response to the varying voltage. - View Dependent Claims (11, 12, 13, 14)
-
-
15. A capacitive gauging system for a laser, said system comprising:
-
a capacitor formed from a structural portion of the laser and a polymer work piece; a radio frequency oscillator configured to detect changes in capacitance of the capacitor; a high-frequency high-order bypass filter coupled to the oscillator, said bypass filter being a greater than 4th order filter to measure minute changes in an output of the radio frequency oscillator; and a gain stage coupled to the radio frequency detector, said gain stage configured to drive a laser head drive mechanism. - View Dependent Claims (16, 17, 18, 19, 20)
-
Specification