* This article is for Japan and translated for reference.
The number of consumers who wish to implement measures to protect themselves from novel coronavirus infection and change their living spaces into a safe environment that is easy to live in is increasing around the world. And now expectations are growing for "ionizers and ozonizers" embedded in air purifiers and air conditioners, etc. to improve the air with ion and ozone effects. To deliver consumer electronics that incorporate air modification features to consumers around the world, we need easy-to-handle devices that can generate concentrated ions and ozone according to use cases. We spoke with a manager who is involved with Murata product planning about the operating principles of ionizers and ozonizers and the strengths of Murata's modules as well as the evidence for PM2.5 removal.
Generating ions and ozone by applying a high voltage
--Please tell us about the differences between an ionizer and an ozonizer.
An ionizer ionizes air molecules to generate and emit ions (O2-, OH-, N2+, etc.). Some products also emit ozone (O3) together with the ions. On the other hand, an ozonizer efficiently generates and emits ozone from oxygen molecules (O2). It does not generate ions. They have generators with different structures and are offered as separate products.
--Under what principles do they respectively generate ions and ozone to achieve effects such as removing particles suspended in the air, sterilization, and deodorization?
In an ionizer, a high DC voltage is applied to a needle electrode to create a charge concentration and a corona discharge, which causes electrons to be exchanged between molecules by energizing the surrounding air molecules (Figure 4). Then the molecules that received the electrons become negative ions. At Murata, we are also able to generate ozone when applying a high voltage by adopting our own ion generation structure.
Ions have an electric charge, and they attract and capture suspended particles with that Coulomb force to remove them from the air. Generally, this feature is used to clean dust, etc. in the air.
In an air purifier, etc. a method that uses a filter to remove particles is also used. However, by using it in combination with an ionizer, it can promote the capture of dust and particles to effectively remove dust, etc. with the filter.
--So under what principles does an ozonizer operate?
In an ozonizer, a high AC voltage is applied to a ceramic substrate that forms an electrode internally to create an electrical discharge on the surface of the substrate (Figure 5). When that happens, the oxygen molecules separate due to the electrical discharge energy and become oxygen atoms. These separated oxygen atoms combine with other oxygen molecules to create ozone.
Ozone has oxidizability. We use this property to make it possible to sterilize, disinfect, and deodorize.
Developed by applying accumulated high-voltage technologies and ceramic substrate technologies
--How long and under what circumstances have ionizers and ozonizers been developed at Murata?
Murata started ionizer development from around 2004 based on the negative ion fad around 2000. Negative ions attracted attention not only as what were referred to as "soothing negative ions" at the time but also as a method for removing PM2.5 and other particles that are detrimental to one's health, and negative ion generators started to be equipped in various consumer electronics.
High-voltage power source technologies and ceramic substrate technologies, etc. were required to create negative ion generators. Murata has assembled a set of technologies that are required in a negative ion generator through the development of high-voltage resistors, high-withstanding-voltage capacitors, and high-voltage transformers that were preceded by flyback transformers. In addition, we thought that we could develop higher-performance ion generators by applying Murata's core technology of ceramic firing and its many years of experience in lamination technology. This is how the company started the development of ionizers.
Then we succeeded in developing ionizers that achieve high reliability in a compact module. Later, we successfully developed an ozonizer product that generates only ozone by adding further improvements to the ion generator structure that uses a ceramic substrate.
--At roughly what scale is the company currently producing ionizers and ozonizers?
Currently, the number of inquiries aimed at novel coronavirus measures is increasing, and we are shipping 400,000 to 500,000 modules per month including both the Japanese and overseas markets. We think that the number will further increase if ionizers and ozonizers are equipped as standard features in air conditioners, etc. as lifestyles adjust to the new normal going forward.
High-reliability Murata modules that can achieve combined effects
--Many companies have undertaken the development of technologies aimed at sterilization and deodorization, etc. using ions and ozone, etc., which are equipped in consumer electronics. Please tell us about the advantages of Murata's technologies for ionizers and ozonizers.
The ability to generate both ions and ozone in one ionizer module is a unique feature of Murata's ionizers. This makes it possible to create an applied product that can be expected to have multiple effects such as sterilization and deodorization as well as air purification when incorporated into an air purifier or air conditioner.
Moreover, Murata's generator is able to generate ions and ozone at a low voltage. By achieving a low voltage, it has a low failure rate, keeps foreign substances from adhering to the generator, and suppresses corrosion of the discharge needle to provide a long service life.
--From the point of view of the user, if they operate an air purifier or other device, they would like to experience an immediate effect, so that is a welcome feature.
However, because ozone is a gas that may affect the human body, it is dangerous to unnecessarily generate a high concentration in a device, etc. that is used all the time. With Murata's products, it is possible to generate a high concentration of ozone in a scenario where people are not involved and suppress the generation of ozone in other situations. We have also prepared ionizer models that suppress the ozone generation rate as much as possible.
Because regulations are applied to the ozone generation amount depending on the country or region of use, such ozone concentration control is important to create applied equipment that conforms with the laws and ordinances of the destination.
--So it is not the case that a high concentration should be created unnecessarily.
Separating the generator and the power supply to improve the degree of design flexibility of applied equipment
In addition, because we adopt a structure that separates the generator and high-voltage power supply, the high degree of mechanical design freedom when embedded in applied equipment can be said to be an advantage. The mounting position may be restricted, because it generates a high voltage. However, the use of an isolation structure increases the degree of freedom when equipped. Moreover, the generated ions and ozone must be radiated or dispersed onto the object using a fan, etc. However, when the generator and high-voltage power supply are placed in the same location, they may interfere with the airflow. With Murata's modules, it is easy to place them in separate locations to create an ideal environment.
--The fact that they are highly reliable and easy to embed in applied equipment would seem to be a significant advantage in extending applied equipment going forward.
Murata's ionizer and ozonizer modules are offered in a form that reconciles the generator and high-voltage power supply specifications to achieve the best performance. There are many user companies that procure each component from different companies to configure the applied equipment. However, if the power supply voltage is too high, the ozone generation may become too high and damage the generator, and if it is too low, the ions and ozone may not be emitted. By designing both together, we tailor and offer effective and high-reliability products.
Preparing products with optimized specifications according to use cases
--Please introduce the lineup of ionizers and ozonizers that the company currently offers.
We have prepared four types of ionizers for cases in which an air purification feature based on the constant use of negative ions is required such as in air purifiers and air conditioners. Within those products, we have assembled a type of ionizer that generates ozone and a type that conversely suppresses it is much as possible to allow for the user to make a selection according to the required feature. The ionizers include types that input a DC power supply and types that input an AC power supply. Thus far, we released AC input products that support AC220 to 240V, but in the spring of 2021 we also plan to release a product with an AC100 to 120V input. In addition, we also have products with different output line lengths to connect the generator and high-voltage power supply in consideration of customer ease of use.
In addition to these four types, we have also prepared models that generate positive ions and models that can effectively remove electricity by embedding them in dryers, etc.
Meanwhile, we have prepared an ozonizer for cases that require sterilizing and deodorizing features only. Currently, we have prepared four types of ozonizers that generate different amounts of ozone. With an on/off feature through an external signal, user companies can set an ozone concentration suitable for the device. In addition, we also have products that are equipped with a heater that can be used even in high-humidity environments. These products are expected to be used in high-humidity environments such as dishwashers and washing machines, etc. Going forward, we plan to release products that can generate a higher amount of ozone.
--So you have considered the use cases and assembled products with the necessary specifications.
We plan to think about the use cases in greater detail while expanding the lineup in the future. When considering global expansion, some have expressed the opinion that AC input modules are easy to handle for Europe and Asia. In the case of previously adopted digital equipment, there was a DC input inside the equipment, so we used that voltage and had customers adopt DC input-type products. However, it is thought that an AC input is needed in order to have "new normal" sterilization features become standard equipped features in every device.
--Please introduce evidence for the effects that can be obtained in the expected applications.
This is an introduction to the results of an in-house evaluation by Murata of the airborne PM2.5 cleaning effect using negative ions generated with an ionizer (Figure 6). A particle size of 2.5 mm or less is called "PM2.5." However, of the particles that were floating in the test space, approximately 85% had a particle size between 0.3 mm and 0.5 mm, approximately 10% were between 0.5 mm and 0.7 mm, and approximately 5% had a size of 0.7 mm or more.
Of these particles, the particles with a size between 0.3 mm and 0.5 mm will continue to float in the air if they are left as is. We verified that running an ionizer promotes the capture of such particles and that particles with the same size had been reduced by more than 40% after 60 minutes.
--PM2.5 is a type of air pollution that has become a problem in China, South Korea, and all of eastern Asia. Looking at these results, an ionizer is essential to maintain one's health.
In addition, ionizers and ozonizers have sterilizing and disinfecting effects.
It was thought that the spread of the novel coronavirus would settle down worldwide, but it has continued on a larger scale through second and third waves. It is believed that continuing to carry out some sort of measures will become essential. I hope that Murata's ionizers and ozonizers can make even a small social contribution in the new normal lifestyle.
Ionizers and ozonizers secretly remove unseen threats
Due to the coronavirus pandemic, people around the world have been forced to live with an awareness that unseen threats are definitely present in their surroundings. However, we are living not only with the coronavirus but also with many unseen threats such as PM2.5, bacteria, and allergens, etc. If we can be clearly aware of those threats similar to the coronavirus and implement measures without fail, we can lead safer, healthier, and higher-quality lives.
Murata says that it will continue to develop and offer ionizers and ozonizers with more effective characteristics going forward to meet the needs of global consumers who have become conscious of living space hygiene and purification. However, because these are tools for supporting measures to combat unseen threats, those effects tend to be difficult to experience. Accordingly, Murata is carrying out tests anticipating various use cases together with universities and evaluation organizations in order to clearly demonstrate the efficacy of ionizers and ozonizers and will continue its efforts to obtain evidence. This article introduced evidence for the efficacy with respect to PM2.5. In addition, we also have test results for various types of efficacy such as deodorizing and mold prevention, etc.
Features that remove unseen threats are becoming essential features that should naturally be equipped in air conditioners and other consumer electronics due to increased consumer awareness of health management and hygiene control. It appears that Murata's ionizers and ozonizers are becoming essential for secretly supporting our health.