An electrical ionizer comprising a fan (5) for producing a laminar flow of air; a positive
ion emitter (6b) for ejecting positive ions into the flow of air; a negative
ion emitter (6a) for ejecting negative ions into the flow of air; a positive
voltage supply (27) to the positive
ion emitter; a
negative voltage supply (28) to the negative ion emitter; and a
microprocessor (30) for controlling the positive and negative voltages to obtain a desired
ion balance in the flow of air. The fan (5) is a crossflow fan, resulting in a highly uniform and laminar beam of air along the entire length of the fan, with reduced gaps in the air flow and consistent velocity of air, improving
ion balance. The use of a crossflow fan also enables the operating mechanism to be contained within a simple “teardrop” profile, and for operative parts of the device, for example the motor, the bearings, and
electronics such as printed circuit boards to be housed outside the air flow, thereby eliminating a possible source of
contamination of the air flow. For a
comparable size of ionizer
enclosure, approximately twice the
mass flow, at higher velocities, can be generated as a similar conventional device using axial fans, and at reduced
noise levels.