A method and device for monitoring operation of a high voltage generator which converts an input voltage into an output voltage which is higher than the input voltage, by measuring at least one first physical quantity which is representative of the input voltage; deriving at least one parameter from the at least one measured first physical quantity; comparing the at least one parameter with a second measured physical quantity which is representative of the magnitude of the output voltage; and producing a response when a predetermined minimum differential exists between the at least one parameter and the second measured physical quantity.

In an electrostatic spray gun, particularly a hand spray gun, for coating workpieces with liquid or powdery coating material, the integrated or atached high-voltage cascade comprises a carrier plate of sintered ceramic that is printed with interconnects and capacitor surfaces. The diodes of the high-voltage cascade can also be printed onto a corresponding carrier plate.

An improved power supply for an electrostatic spray gun device having a voltage multiplier circuit adjusts to variations in the output load conditions of the multiplier circuit and dynamically modifies the operational loadline of the multiplier circuit in order to maintain optimal operating conditions for the spray gun device notwithstanding output load variations. The power supply utilizes a loadline manipulation circuit coupled to a feedback circuit that monitors the output load, and the manipulation circuit, in response to a feedback signal from the feedback circuit that is proportional to the output load, varies the input voltage level to the multiplier circuit to modify the loadline of the power supply in response to varying load conditions. The manipulator means of the power supply has memory means to store a variety of external commands which will control the manipulation means and a user interface to enter the external commands into the memory. The power supply also comprises a voltage limiting circuit coupled to the output of the multiplier circuit which regulates the output voltage level of the multiplier circuit so that when the output load current increases above a predetermined maximum level the output voltage is reduced to reduce the high voltage stress on the multiplier circuit and high voltage circuitry and reduce the amount of insulation that must surround the multiplier circuit and high voltage circuitry of the power supply in order to insulate it from ground potential.

A high magnitude potential supply comprises a first circuit for generating a first signal related to a desired output high magnitude potential across a pair of output terminals of the supply, a second circuit for generating a second signal related to an output current from the high magnitude potential supply, and a third circuit for supplying an operating potential to the high magnitude potential supply so that it can produce the high magnitude operating potential. The third circuit has a control terminal. A fourth circuit is coupled to the first and second circuits and to the control terminal. The fourth circuit receives the first and second signals from the first and second circuits and controls the operating potential supplied to the high magnitude potential supply by the third circuit. A fifth circuit is provided for disabling the supply of operating potential to the high magnitude potential supply in certain conditions so that no high magnitude operating potential can be supplied by it. The fifth circuit is also coupled to the control terminal.

A high magnitude potential supply comprises a first circuit (220, 224) for generating a first signal related to an output high magnitude potential (KV) across a pair of output terminals (113 and ground) of the supply, a second circuit (210, 218) for generating a second signal related to a desired output current from the high magnitude potential supply, and a third circuit (Q2B, Q2C, Q7 and associated components) for supplying an operating potential (VCT) to the high magnitude potential supply so that it can produce the high magnitude operating potential. The third circuit has a control terminal (COMP terminal of 86). The supply further comprises a fourth circuit (86) coupled to the first (220, 224) and second (210, 218) circuits and to the control terminal (COMP terminal of 86). The fourth circuit (86) receives the first and second signals from the first (220, 224) and second (210, 218) circuits and controls the operating potential supplied to the high magnitude potential supply by the third circuit (Q2B, Q2C, Q7 and associated components). The supply further comprises a fifth circuit (84, 240, 242, 244) for disabling the supply of operating potential to the high magnitude potential supply so that no high magnitude operating potential can be supplied by it. The fifth circuit (84, 240, 242, 244) is also coupled to the control terminal (COMP terminal of 86).