Patent ID: 7538556

Claim:
A method of evaluating a spot-type ionizer in which a driving voltage is applied to a discharge needle for corona discharge to generate plus ions and minus ions and, with air externally supplied, ion air containing the plus ions and the minus ions generated from the discharge needle is blown in a spot manner from a nozzle opening onto a target to neutralize static electricity, the method including: placing the spot-type ionizer above and apart from a measurement plate of a charge-plate monitoring device; attaching a grid using a metal net to the nozzle opening of the ionizer; setting an air pressure of the compressed air at a predetermined value and setting a use distance between the measurement plate and the nozzle opening at a predetermined distance; operating the spot ionizer to measure by the charge-plate monitoring device an ion balance and an ion balance variation for comparison with respective threshold values, and if the ion balance and the ion balance variation are equal to or lower than the respective threshold values, making a determination as accepted, and if the ion balance and the ion balance variation are larger than the respective threshold values, making a determination as failed; if the determination is made as accepted regarding the ion balance and the ion balance variation, with the measurement plate being charged with a predetermined start voltage by the charge-plate monitoring device, measuring a static elimination time until the predetermined start voltage is decreased to a predetermined static-elimination voltage by an operation of the ionizer; comparing the static elimination time with a predetermined threshold time, if the static elimination time is longer than the threshold time, measuring the static elimination time while increasing the air pressure, and determining an air pressure with the static elimination time being equal to or shorter than the threshold time as an optimal air pressure with the set use distance; and generating an acceptance result for the grid with a combination of the set use distance and the optimal air pressure as a use condition.