High impedance diagnostic for gun driver and method
AssigneeNordson Corporation
InventorPeter W. Estelle
Life of this patent
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Abstract
An apparatus for detecting a high impedance load on an output of a driver circuit having a power switching circuit providing output signals to a coil. Each output signal results from a drive signal that has a waveform comprising a higher magnitude initial peak period followed by a lower magnitude hold period. The driver circuit has a feedback circuit providing a difference signal as a function of a difference between an output signal and a corresponding drive signal. A diagnostic circuit connected to the driver circuit provides a high impedance error signal in response to detecting the difference signal crossing a threshold magnitude during a higher magnitude initial peak period of a drive signal.
Claims25
An apparatus for use with a fluid dispensing gun having a driver circuit with a load connected thereto, the driver circuit having a power switching circuit providing output signals to a gun coil in the load, each output signal occurring in response to a drive signal having a waveform comprising a higher magnitude initial peak period followed by a lower magnitude hold period, the apparatus comprising:
- a diagnostic circuit connected to the driver circuit, said diagnostic circuit providing a high impedance error signal in response to detecting during only the higher magnitude initial peak period of the drive signal, a voltage of the output signal exceeding a predetermined value, the high impedance error signal representing a high impedance of the load.
An apparatus for detecting a high impedance of a load connected to a driver circuit of a fluid dispensing gun, the driver circuit having a power switching circuit providing output signals to a gun coil in the load, each output signal resulting from a drive signal that has a waveform comprising a higher magnitude initial peak period followed by a lower magnitude hold period, the driver circuit further having a feedback circuit providing a difference signal as a function of a difference between an output signal and a corresponding drive signal, the apparatus comprising:
- a source of a reference signal;
- and
- a diagnostic circuit connected to the driver circuit, said diagnostic circuit providing a high impedance error signal in response to detecting the difference signal crossing a magnitude represented by said reference signal, the high impedance error signal representing a high impedance of the load.
An apparatus for detecting a high impedance of a load connected to a driver circuit of a fluid dispensing gun, the driver circuit having a power switching circuit providing output signals to a gun coil in the load, each output signal resulting from a drive signal that has a waveform comprising a higher magnitude initial peak period followed by a lower magnitude hold period, the driver circuit further having a feedback circuit providing a difference signal as a function of a difference between an output signal and a corresponding drive signal, the apparatus comprising:
- a source of a reference signal;
- and
- a diagnostic circuit connected to the driver circuit, said diagnostic circuit providing a high impedance error signal in response to detecting the difference signal crossing a magnitude represented by said reference signal during a stable portion of the higher magnitude initial peak period, the high impedance error signal representing a high impedance of the load.
An apparatus for detecting a high impedance of a load in an output circuit that includes a coil of a fluid dispensing gun, the apparatus comprising:
- a driver circuit adapted to be electrically connected to the output circuit, the driver circuit providing an output signal resulting from a drive signal having a waveform comprising a higher magnitude initial peak period followed by a lower magnitude hold period;
- said driver circuit having a switch for terminating the output signal;
- and
- a diagnostic circuit connected to said driver circuit, said diagnostic circuit providing a high impedance error signal to said switch in response to a voltage of said output signal exceeding a threshold magnitude.
An apparatus for detecting a high impedance of a load in an output circuit that includes a coil of a fluid dispensing gun, the apparatus comprising:
- a driver circuit adapted to be electrically connected to the output circuit, the driver circuit providing an output signal resulting from a drive signal having a waveform comprising a higher magnitude initial peak period followed by a lower magnitude hold period;
- said driver circuit comprising
- a detector connected to the output circuit for detecting a feedback signal through the coil in response to said output signal, and
- an error amplifier connected to said detector and providing a difference signal as a function of a difference between said output signal and said drive signal;
- and
- a diagnostic circuit connected to said driver circuit, said diagnostic circuit providing a high impedance error signal in response to said difference signal exceeding a threshold magnitude.
A method of detecting a high impedance of a load having a coil on an output of a driver circuit of a fluid dispensing gun, the method comprising:
- providing a drive signal having a waveform comprising a higher magnitude initial peak period followed by a lower magnitude hold period;
- applying an output signal to the coil in response to the drive signal;
- and
- providing a high impedance error signal in response to detecting a voltage magnitude of the output signal crossing a threshold magnitude.
A method of detecting a high impedance of a load having a coil on an output of a driver circuit of a fluid dispensing gun, the method comprising:
- providing a drive signal having a waveform comprising a higher magnitude initial peak period followed by a lower magnitude hold period;
- applying an output signal to the coil in response to the drive signal,
- producing a difference signal as a function of a difference between the output signal and the drive signal;
- and
- providing a high impedance error signal in response to a sample of the difference signal exceeding a threshold magnitude.
Dependencies are inferred from the claim text.