Exploring a popular Japanese air purifier.

This device is hugely popular in Japan and India. It claims to clean your home environment by creating charged molecules of hydrogen and oxygen from water in the air, that are then surrounded by water molecules until they find airborne contaminants like spores and viruses, and by extracting a hydrogen atom from the target they disable it, converting back to water in the process.
Sounds wonderful, but is hard to prove without a hugely complex lab. What I can prove is that they produce trace levels of ozone. But I'd like to stress that the levels produced are very low and diffused thoroughly into the air by a powerful fan system.

These are most certainly not in the league of the ionic breeze type air purifiers that put out undesirably high levels of ozone. I'd describe the plasmacluster units as putting out a level on a par with natural outdoor air.

Many of the marketing videos show excitable Japanese youths running around in white overalls demonstrating how the units can remove strong odours applied to thin fabric sheets, defeating the smell abilities of tracker dogs. There are also timelapse videos showing things like a piece of bread remaining mould free in a sealed container with a plasmacluster emitter, or a setup passing a mist of flu virus through a chamber with a plasmacluster emitter and showing reduced petri dish growth.
But as I demonstrated in the video, that is partly - if not completely down to the smellable ozone concentration in an enclosed space. (You can smell ozone at just 0.1 parts per million.)

The construction inside this unit is amazing. Totally over-engineered to the traditional Japanese levels that we'd expect. From the power supply and control PCB to the breathtakingly beautiful emitters with their strangely retro, but time tested circuitry - everything is just well engineered for reliability and safety. Although made in China, it's definitely made to strict Japanese standards.

The fan is a low voltage electronic unit. Most likely brushless with four connections for power, control and probably feedback. It also has a thermal fuse which breaks power to the fan and plasmacluster emitters. It's surprisingly quiet, even at full power which it ramps up to in distinct steps. It pushes through a huge volume of air to diffuse the treated air into the room.

The emitter units are very intriguing. There are a multiple of modules used per unit, probably according to the space it is intended for. In this unit there are four modules, but it alternates between two pairs at a rate of about 1Hz. This may be to spread the duty for longer emitter-needle life.
The emitter circuitry is powered at 12V and has polarity protection. Internally the voltage is stepped up in two stages, firstly to about 100V where it charges a capacitor until the threshold of a SIDAC is reached, whereupon the capacitor is dumped through a high turn ratio high voltage transformer to step it up to a level where the ionisation/corona can occur at the needles.

A particular oddity is that there is no reference to mains ground, but instead the metal rings in front of the needles are connected to one end of the high voltage winding and the two needles each have their own high voltage diode referenced to the other end of the winding in opposing polarities, so that one needle is active on the positive pulse and one on the negative pulse. This does result in a separate positive and negative charge appearing in front of the emitter units simultaneously, but probably as alternate high speed bursts.

The needle in front of an opposite polarity ring does predictably result in a slight corona discharge and the resultant low level ozone production.

So my thoughts on this unit? It's really well made. The circuitry is formal and there's a surprising amount of protection built in. It's very hard to test whether the unit does produce the plasmacluster effect they describe. My own thoughts are that it is a well engineered ozone generator that produces a level of ozone similar to normal outdoor air.
Ozone occurs in nature and has an important cleaning effect in the environment. In a sealed building with no natural airflow, any ozone that enters with outdoor air is quickly absorbed by contaminants leaving the air "stagnant". As such I approve of ozone production at naturally occurring levels, and the use of a powerful fan stirring that into the air is a good approach.

Sharp may be trying to avoid the attention of the faux medical "experts" who like to loudly announce that everything causes cancer.

These machines only create naturally occurring levels of ozone in the air.

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