Titanium oxide (TiO2) has a high adhesive force regardless of the type of substrate coated therewith, and exhibits photocatalytic activity when light (mainly, ultraviolet light) that may cause a photo-excited reaction is radiated thereto.
In particular, a photocatalytic reaction using titanium oxide has antibacterial and deodorization effects, and is often employed for air cleaning. For example, a method of eliminating odors in air in such a manner that a photocatalytic reaction occurs by irradiating a photocatalytic filter coated with titanium oxide (a TiO2 ceramic form filter) with ultraviolet light while air passes through the photocatalytic filter has been widely used.
Titanium oxide is typically used in the form in which it is coated on a base, rather than being used per se. Therefore, the shape of a photocatalytic filter coated with titanium oxide is generally determined according to the shape of the base.
Deodorization using titanium oxide is mainly employed in medium-large air conditioners, whereas it is rarely employed in compact or home air cleaners.
In a large air conditioner having a large flow amount of air and a large flow area of air, deodorization may be performed without any problems as long as the air conditioner generates intense ultraviolet light and includes a large-sized photocatalytic filter.
However, in a compact air cleaner, the size of a photocatalytic filter is limited, the size of a device for generating ultraviolet light is limited, and the flow amount of air is small. Accordingly, it is necessary to develop an air cleaner having a deodorization effect above a certain level even when the compact air cleaner has a compact photocatalytic filter and generates weak ultraviolet light. In particular, electricity consumption as well as noise must be considered in a home air cleaner. However, since conventional techniques focus on medium-large air conditioners, there is hardly any technology suitable to adapt to new environments.
When ultraviolet light is intensively radiated with the intention of increasing the efficiency of a photocatalytic filter in a compact air cleaner, the material in a region, to which the ultraviolet light is intensively radiated, is rapidly transmuted or the large quantity of electricity is consumed in the state in which the efficiency of the photocatalytic filter is not ensured. In addition, the costs of the compact air cleaner will be increased in that more UV LEDs are installed and UV LEDs have a short service life.
In addition, it may be expected that the air cleaner has increased efficiency when it uses UV LEDs, each having a peak wavelength of about 270 nm known as a wavelength range in which titanium oxide is most well absorbed. However, since the irradiance of ultraviolet light radiated from the UV LED having a peak wavelength of 270 nm is actually considerably weak compared to power used in the air cleaner, deodorization efficiency may be poor even though the UV LEDs having a peak wavelength of 270 nm are used in the air cleaner.
The shape or dimension of a photocatalytic filter, and the relationship between the photocatalytic filter and an ultraviolet light source must be newly researched such that the photocatalytic filter has high efficiency even when having a small size. In particular, the shape or dimension of the photocatalytic filter is closely related with air resistance, and thus a fan applied to a compact air cleaner has limited standard or performance. Therefore, in order for the compact air cleaner to have own function, it is important to smoothly maintain the flow of air by reducing resistance to the flow of air.
Moreover, there is a need to find a method of manufacturing a photocatalytic filter such that the photocatalytic filter itself may have high photocatalytic activation efficiency. The technique that can obtain a higher deodorization effect only by a photocatalytic filter having a small volume is one of techniques required for compact air cleaners.
In addition, when a compact air cleaner is configured of UV LEDs and photocatalytic filters, the arrangement order of fans and filters is a major consideration. Conventional medium-large air conditioners first filter out dust through dust collection filters and then perform deodorization using photocatalytic filters. However, these filters are major components that cause the pressure of air to be lowered. Therefore, even when this structure is applied to compact air cleaners, the photocatalytic filters may not properly exhibit functions compared to the case that it applied to the medium-large air conditioners.
In addition, harmful bacteria floating in air must be eliminated in home. In this case, it is difficult to apply HEPA filters, known to filter out bacteria, to small air cleaners since the HEPA filters have strong air resistance. Furthermore, when air resistance is increased due to the installation of the HEPA filters, this may rather affect the deodorization reactions of photocatalytic filters. Accordingly, it is necessary to find alternative methods for efficiently eliminating bacteria without interrupting the air flow in air cleaners.
In particular, the vehicle interior is a space that requires the installation of an air cleaner having high deodorization efficiency since odors due to smoking are rarely removed from the vehicle interior. Since the vehicle interior is very small, there is a need for an air cleaner which has the significant ability to purify air without occupying a large space. In particular, since the vehicle rolls heavily, the air cleaner need to have a structure that is properly maintained at a fixed position and to be easily installed, under such environments. In particular, since most of vehicle air cleaners are options provided from vehicle manufacturers, there is a problem in that the air cleaners installed in a vehicle cannot be continuously used other vehicles. Therefore, the demand for portable air cleaners will increase in the technical field of vehicle air cleaners.
In addition, when an air cleaner is used for a vehicle, the air cleaner is used only during the operation of the vehicle, and thus a use pattern in which the air cleaner operates and stops is repeated. According to the experiment of such a use pattern for an air cleaner having a photocatalytic filter, it may be seen that, when the air cleaner stops for a long time and operates again, odors are discharged from the outlet port of the air cleaner in the initial stage of operation thereof, compared to the case in which the photocatalytic filter is not applied to the air cleaner. Considering that the vehicle air cleaner having a small size repeatedly operates and stops and the operation time of the vehicle is short, customers may feel displeasure with odors discharged from the air cleaner whenever the vehicle is operated, resulting in a deterioration in satisfaction for product use.
Moreover, if it is difficult to perform the maintenance of an air cleaner and manufacture it by the overemphasis of functions thereof, commercial values are deteriorated and a user experiences inconvenience. For this reason, there is a need for an air cleaner which has a simple structure, is easily manufactured, and is convenient for maintenance.