GB2609000A

GB2609000A - An air purifier

Info

Publication number: GB2609000A
Application number: GB2110216.5A
Authority: GB
Inventors: Ha Duc
Original assignee: Omega Dot Ltd
Current assignee: Omega Dot Ltd
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2023-01-25
Anticipated expiration: 2041-07-15
Also published as: GB2609000B; GB202110216D0

Abstract

An air purifier 10 comprising a housing 100, a fan 130, and air filter 131 and a UV-C radiation source 132 for disinfecting air drawn through the housing. The air purifier additionally comprises a plurality of sensors 112 configured to detect at least one characteristic of air quality and at least one characteristic of human presence or absence. The air purifier further comprises a microcontroller 134 configured to selectively control the fan and the UV-C radiation source to operate the air purifier in one of a plurality of operation modes in dependence on information received from the plurality sensors. The multiple modes have the fan speed and UV-C radiation are operated at different intensities depending on the mode, with the modes of operation able to be chosen based on the plurality of sensors.

Description

AN AIR PURIFIER

TECHNICAL FIELD

The present invention relates to an air purifier, and more specifically to an air purifier incorporating a UV-C radiation source.

BACKGROUND

Air purifiers are devices used to improve indoor air quality that use a fan to draw air through an air filter to remove undesirable elements from the air. These undesirable elements include contaminants, allergens, germs and viruses. Air purifiers are used in commercial, residential and medical settings to improve air quality.

It is known to use short-wavelength ultraviolet (UV-C) light to disinfect tools, surfaces or substances because it has the ability to kill or inactivate microorganisms by destroying their nucleic acids and disrupting their DNA. UV-C enabled air purifiers use UV-C technology and its germicidal, virucidal and fungicidal properties in combination with filters to increase their effectiveness.

The effectiveness of air purifiers at removing undesirable elements from the air, or clean air delivery rate (CADR), is related to the type of air filters and the amount of air drawn, which is dictated by the size and speed of the fans. Large commercially graded air purifiers can provide a suitable CADR at low fan speeds producing little noise or discomfort to nearby people. However, such larger air purifiers are difficult to move and are typically affixed to an air handler unit or a heating, ventilation and air conditioning unit. Smaller stand-alone commercially graded air purifiers are also available, providing a flexible and portable solution to users. However, such smaller air purifiers may need to operate at high fan speeds to produce a suitable CADR, resulting in noise and discomfort to nearby people.

SUMMARY OF THE INVENTION

According to an aspect of the invention, there is provided an air purifier comprising: a housing; a fan for drawing air through the housing; an air filter; a UV-C radiation source for disinfecting air drawn through the housing; a plurality of sensors configured to detect at least one characteristic of air quality and at least one characteristic of human presence or absence; and, a microcontroller configured to selectively control the fan and the UV-C radiation source to operate the air purifier in one of a plurality of operation modes in dependence on information received from the plurality sensors.

The air purifier advantageously provides air that is both filtered by an air filter and irradiated by a UV-C radiation source to maximise the removal and/or incapacitation of undesirable elements from the air. Moreover, the air purifier comprises a plurality of operation modes that allow the air purifier to tailor its operation in different situations depending on the CADR required and whether UV-C radiation is required. In addition, the air purifier is capable of selectively controlling the fan and the UV-C radiation source in dependence of information received by sensors, which advantageously allows for the control of the air purifier to be at least partly automated.

In embodiments of the invention, the microcontroller may be configured to selectively control the UV-C radiation source to operate at a plurality of different UV-C radiation intensities. Operating the UV-C radiation source at lower UV-C radiation intensities advantageously saves energy and reduces unnecessary exposure to the components of the air purifier, particularly to the air filter. On the other hand, operating the UV-C radiation source at higher UV-C radiation intensities advantageously maximises the germicidal effectiveness of the UV-C radiation source.

In embodiments of the invention, the plurality of operation modes may comprise: a first mode in which the fan and the UV-C radiation source are not operated; a second mode in which the fan is operated at a fan speed which is dependent on a detected air quality; a third mode in which the fan is operated at a first speed and the UV-C radiation source is operated at a first intensity; a fourth mode in which the fan is operated at a second speed and the UV-C radiation source is operated at a second intensity.

The provision of at least four operation modes each controlling the fan and the UV-C radiation source differently allows the air purifier to flexibly tailor its operation in response to changes in the air purifier's environment.

Each of the first speed and the first intensity may be lower than the second speed and second intensity, respectively. The provision of a first speed and a second speed provides the air purifier with the option to select the lower first speed, which will produce less noise and be more comfortable to a nearby user, or to select a higher second speed, which will achieve a greater CADR. The provision of a lower first intensity and a higher second intensity allows the air purifier to select a UV-C intensity suited to the selected fan speed such that the UV-C intensity will sufficiently irradiate the given air flowrate, therefore saving energy. Moreover, the provision of a lower first intensity advantageously reduces the damage to the air purifier's components from direct exposure to UV-C radiation compared to the higher second intensity. In addition, the provision of a lower first intensity reduces the amount of blue tint visible on the filter through the inlet holes of the air purifier housing when the UV-C radiation source is switched on compared to the higher second intensity. This reduces possible user anxiety about direct exposure to UV-C radiation.

More specifically, the first speed may provide a minimum CADR and the value of the second speed may be at least 1.5 times greater than the value of the first speed. The fan speed being linked to a minimum CADR advantageously ensures that the air purifier provides sufficient air circulation for a given room as opposed to only providing a generic fan speed that may be unsuitable for a given room's size.

In embodiments of the invention, the microcontroller may be configured to selectively change the operation mode from any one of the first mode, the second mode or the fourth mode to the third mode when the plurality of sensors detects at least one characteristic of human presence. The microcontroller being configured with a change logic to selectively change the operating mode into the third mode as above described advantageously ensures that the air purifier is operated at a fan speed that does not produce noise that would cause discomfort to people nearby or impede conversations. It also ensures that the air purifier is operated at a UV-C radiation intensity suitable to sufficiently irradiate the air flowrate created by the fan speed and avoid user anxiety as above mentioned.

The plurality of sensors may comprise a PIR sensor and/or a light sensor and the at least one characteristic of human presence may be a motion and/or an increase in ambient light. Using a proximity infrared (PIR) sensor to detect motion is a cost effective and reliable way to determine human presence. The lack of motion detection by the PIR sensor can also be used to determine human absence. An increase in ambient light refers to the increase in illuminance over a period of time. The provision of a light sensor enables the air purifier to start purifying the air when a room's lights are turned on and to greet an approaching person with a purified airflow.

In embodiments of the invention, the microcontroller may be configured to selectively change the operation mode from the first mode to the second mode when a detected air quality is below a threshold value, and to selectively change the operation mode from the second mode to the first mode when a detected air quality is above a threshold value. The microcontroller being configured with a change logic to selectively change the operating mode between the first mode and the second mode as above described advantageously allows the air purifier to maintain a suitable level of air quality while spending the least amount of time and energy required, therefore saving energy.

The plurality of sensors may comprise a particulate matter sensor and the at least one characteristic of air quality may be a detected mass concentration of particulate matter in the air. The size of particles is directly linked to their potential for causing health problems. Small particles less than 10 micrometres in diameter pose the greatest problems, because they can get deep into a person's lungs, and some may even get into a person's bloodstream. The provision of a particulate matter sensor therefore advantageously allows the air purifier to monitor a key metric of air quality.

In embodiments of the invention, the microcontroller may be configured to selectively change the operation mode from the third mode to the fourth mode when no motion is detected for a period of time, and to selectively change the operation mode from the fourth mode to the second mode after a period of time. The microcontroller being configured with a change logic to selectively change the operating modes after certain periods of time ensures that the air purifier does not remain in an operation mode for longer than it needs to, particularly energy-intensive modes. This advantageously saves energy.

Moreover, the microcontroller being configured with a change logic to selectively change the operating mode from the third mode to the fourth mode and advantageously ensures that a thorough purification of the air is conducted when no one will be disturbed (since the lack of motion detected over a period of time indicates human absence). The microcontroller being configured with a change logic to selectively change the operating mode from the fourth mode to the second mode advantageously ensures that the air purifier will continue purifying the air if the air quality is still not suitable after the fourth mode's thorough purification.

In embodiments of the invention, the plurality of sensors may comprise a microphone and the at least one characteristic of human presence is a detected sound above a threshold value, and the microcontroller may be configured to selectively change the operation mode from the first mode to the third mode when human presence is detected.

The air purifier being able to determine a human presence by detecting sound is particularly suitable for large or open rooms with little light variation. For example in an office reception area or a hallway the light may need to be constantly switched on for safety purposes and noise may be detected by the air purifier before a person approaches the vicinity of the air purifier, allowing the air purifier to greet people with a purified airflow.

In embodiments of the invention, in the third operation mode the air purifier may operate the fan and the UV-C radiation source for a period of time, the period of time being reset when a motion is detected. The microcontroller being configured with a change logic to selectively operate the fan and the UV-C for a certain period of time that is reset upon the detection of motion advantageously saves energy as it ensures that these components are not being needlessly operated. This may be particularly useful in areas of intermittent foot traffic.

In embodiments of the invention, the housing may be substantially cylindrical and may define a fan cavity and an air purification cavity, the fan cavity being configured to receive the fan and the purification cavity being configured to receive the air filter and the UV-C radiation source. The fan cavity may be located around a longitudinal axis above the purification cavity, and the fan may be configured to draw air through inlet openings in a lower side wall of the housing into the purification cavity. A cylindrical housing allows for 360-degree air flow and so promotes more homogeneous air purification.

The arrangement of the fan cavity above the purification cavity advantageously allows for the design of a compact air purifier. The longitudinal axis may be defined as the centreline of the housing along its height. Moreover, the UV-C radiation source being located in the purification cavity together with the air filter advantageously avoids direct UV-C radiation from being emitted outside the air purifier and causing harm to people in its vicinity.

S

The housing may comprise an upper side wall having a plurality of outlet openings for directing air driven from the fan cavity. The outlet openings may be collectively configured to direct a cone of air upwardly away from the housing. The provision of outlet openings arranged in such a way advantageously directs purified air closer to peoples' faces, reducing the chance of them inhaling non-purified air.

In embodiments of the invention, the UV-C radiation source may be arranged proximate to the air filter to irradiate air that has passed through the air filter. Other air purifiers that comprise UV-C technology have a sequential design wherein the air is moved from a filtering section to a different UV-C irradiation section. In contrast, the arrangement of the UV-C radiation source proximate to the air filter to irradiate the air as it passes through the air filter advantageously allows for the design of a more compact air purifier.

The wavelength of the UV-C radiation emitted by the UV-C radiation source may be within the range of 100nm and 280nm, more preferably around 253.7nm. The UV-C radiation provides a radiation having a wavelength that is close to the most effective wavelengths for germicidal applications, providing the air purifier with good germicidal and virucidal abilities.

The UV-C radiation source may comprise at least two mercury vapour bulbs, each preferably configured to produce an intensity of 10pW/m2 at a distance of lm. Such UV-C radiation sources provide more than sufficient light intensity to kill airborne particles of the SARS-00V-2 virus.

The air filter may be a cylindrical filter, and preferably a 3-stage filter incorporating a nylon pre-filter stage, a HERA filter stage and an activated charcoal stage. This advantageously provides a significant removal of undesirable elements from the air as it is drawn into the purification cavity, resulting in a very effective purification of the air.

In embodiments of the invention, the air purifier may be Internet of Things (IoT) enabled. The microcontroller may be further configured to communicate wirelessly with one or more of a smartphone, remote server and cloud server to provide a data feed from the plurality of sensors and to receive control instructions.

The data feed may comprise information metrics on the air quality and human presence over a period of time. The microcontroller may be responsive to control instructions to modify one or more operating parameters of the air purifier.

The user may therefore be advantageously provided with valuable information on the foot traffic and air quality of the air purifier's location, that can be reviewed on a designated website/mobile application, and with the flexibility to change the operating parameters to fit their specific requirements. The data can be used to understand the air quality and the room condition of the space if needed, use the past data to compare with the current data to see any changes in the air quality and the room condition.

This allows the user to gain a better insight of the space of the air purifier's location.

In embodiments of the invention, the air purifier may be a compact turbo air purifier. The reduced size and weight of a compact turbo air purifier compared to a standard air purifier allow for the compact turbo air purifier to be used in a wide range of situations providing a user with greater flexibility.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred example of the present invention will now be described in detail with reference to the accompanying drawings, in which: Figure 1A shows a perspective view of an air purifier; Figure 1B shows a longitudinal cross-section of the air purifier from a side view; Figure 1C shows a longitudinal cross-section of a top casing of the air purifier from a front view; Figures 1D and lE show radial cross-sections of the air purifier; Figure 2 shows a schematic diagram of the air purifier's operation; and, Figure 3 shows a flow diagram of the change logic in accordance to which the air purifier is configured.

DETAILED DESCRIPTION

The present invention provides an improved air purifier comprising an air filter and a UV-C radiation source. The air purifier is particularly suited for commercial, public or otherwise shared spaces that require a portable and adaptable air purification solution such as offices and hospitals.

An exemplary air purifier 10 is shown in Figure 1A, with cross-sectional views of the air purifier 10 shown in Figures 1B-1E. As shown in Figure 1, the air purifier 10 comprises a housing 100 and a plurality of sensors. The housing 100 is substantially cylindrical in shape and comprises a top casing 101 and a bottom casing 102. The top casing 101 defines a lower side wall 103 towards its bottom end and an upper side wall 104 towards its upper end, in use, the lower side wall 103 being in contact with the bottom casing 102.

The diameter of the top casing 101 varies along its length, the diameter of the top casing 101 at its bottom end being greater than the diameter at its upper end and the diameter at its bottom end being equal to the diameter of the bottom casing 102. In addition, the diameter of the top casing 101 at a point between the lower side wall 103 and the upper side wall 104 is smaller than the diameter at any other point along its length, providing the housing 100 with a curved surface along a portion of its length. The housing 100 additionally comprises an upper inner wall disposed within the upper side wall 104. The upper inner wall is substantially cylindrical and parallel to the lower side wall 103.

The housing 100 comprises a plurality of openings. The housing 100 comprises a plurality of inlet openings radially arranged along a portion of the lower side wall 103 and a plurality of outlet openings radially arranged along a portion of the upper side wall 104. The openings being radially arranged advantageously allows for 360 degree air circulation around the air purifier 10.

The plurality of inlet openings comprises a first plurality of inlet openings 105 arranged in a plurality of rows along a length of the lower side wall 103 forming a mesh-liked surface. The plurality of inlet openings also comprises a second plurality of inlet openings 106 arranged in a row along a length of the lower side wall 103. The second plurality of inlet openings 106 comprises four openings equidistantly distributed along the lower side wall 103.

The plurality of outlet openings comprises a first plurality of outlet openings 107 located in the upper inner wall and arranged in a plurality of rows along a length of the upper inner wall forming a mesh-like surface. The plurality of outlet openings also comprises a second plurality of outlet openings 108 arranged in a row along a portion of the upper side wall 104. The first and second pluralities of outlet openings are positioned in overlapping arrangement.

Each opening of the pluralities of inlet openings and the first plurality of outlet openings has an oval shape. Each opening of the second plurality of outlet openings 108 has a tear-drop shape. It will be appreciated that in other embodiments, the housing may comprise other arrangement or number of openings. For example, in an alternative embodiment, the housing may not comprise a second plurality of inlet openings and air may only be drawn into the housing via a first plurality of inlet openings.

The housing 100 further comprises ventilation openings 109 located in the bottom casing 102 for ventilating electronic components used to control the air purifier. The air purifier 10 additionally comprises a power cable 110 and a power button 111 located in the bottom casing 102.

The air purifier comprises four proximity infrared (FIR) sensors 112, for detecting a motion, the FIR sensors radially protruding from the lower side wall 103. The air purifier 10 also comprises a light sensor 113, for detecting a change in illuminance over time, also located in the lower side wall 103.

The housing 100 comprises a handle 114 disposed at its top end for convenient transportation of the air purifier 10.

It will be appreciated that in other embodiments the air purifier may have a differently shaped housing such as for example a housing having a square, rectangular, triangular or oval cross-section. The diameter of the housing may be continuous over the length of the housing. The air purifier may comprise any number of openings and sensors arranged in any suitable way. In another embodiment, the air purifier may comprise a touch screen and the housing may comprise an opening for allowing the touchscreen to protrude from the housing.

Figure 1B shows the internal arrangement of the air purifier 10 in greater detail. The housing 100 defines a fan cavity 120, a purification cavity 121 and an electronics cavity 122. The housing 100 additionally comprises a curved top surface 123 and a flat bottom surface 124.

The fan cavity 120 receives a fan 130, the purification cavity 121 receives an air filter 131 and an UV-C radiation source 132, and the electronics cavity 122 receives a microcontroller 134 and pluralities of electronic components 140, 150. In particular, the microcontroller 134 shown in Figure 15 is a Raspberry Pi 3 model A+.

The fan cavity 120 is located around a longitudinal axis above the purification cavity 121. The purification cavity 121 is, in turn, located around the longitudinal axis above the electronics cavity 122. The longitudinal axis may be defined as the centre axis of the housing along its height. Moreover, the fan 130 is located inside the fan cavity such that its axis of rotation and the longitudinal axis are coaxial.

More specifically, the fan cavity 120, the purification cavity 121 and the electronics cavity 122 are disposed such that the centreline of the housing 100, the centreline of the fan cavity 120, the centreline of the purification cavity 121 and the centreline of the electronics cavity 122 are coaxial.

As shown in Figure 15, the fan cavity 120 extends between the upper side wall 104 and the lower side wall 103 of the top casing 101. The purification cavity 121 is contained within the lower side wall 103 of the top casing 101. The electronics cavity 122 is contained within the bottom casing 102.

In addition to the pluralities of electronic components 140, 150, discussed in more detail below, the electronics cavity 122 receives the power cable 110 and the power button 111.

The fan 130 is configured to, in use, draw air through the first plurality of inlet openings 105 and the second plurality of inlet openings 106 into the purification cavity 121. The fan 130 extends across a majority of the length of the fan cavity 120 and the diameter of the fan cavity 120 is substantially equal to the width of the fan 130 (i.e. including the width of the fan blades).

The air filter 131 is a cylindrical filter arranged in the periphery of the purification cavity 121 such that an inner surface of the air filter 131 defines a volume of the purification cavity 121 in which the filtered air can be irradiated by the UV-C radiation source 132. The air filter 131 is arranged with respect to the plurality of inlet openings 105, 106 such that all air drawn into the purification cavity 121 has been filtered by the air filter 131. More specifically, the air drawn through the first plurality of inlet openings 105 is drawn perpendicularly to the length of the air filter 131 and the air drawn through the second plurality of inlet openings 106 is drawn parallel to the length of the air filter 131. The air filter 131 is a 3-stage filter incorporating a nylon pre-filter stage, a High Efficiency Particulate Air (HEPA) filter stage and an activated charcoal stage.

The UV-C radiation source 132 comprises at least two UV-C bulbs parallel to and equidistantly spaced with respect to the longitudinal axis of the air purifier 10. The light emitting portion of each of the at least two UV-C bulbs extends across a majority of the length of the purification cavity 121. Each of the UV-C bulbs are a 5 W UV-C mercury vapour bulb configured to each produce an intensity of 10 pW/m2 at a distance of 1 m. In a preferred embodiment, the diameter of the purification cavity is 106 mm and the furthest distance that air can be from the bulb in the purification cavity is 53 cm such that each of the UV-C bulbs is capable of producing a light intensity more than sufficient to incapacitate an airborne particle of the SARS-00V-2 virus (90 pW/cm2). It will however be appreciated that in alternative embodiments the air purifier may comprise any type and number of UV-C bulbs as long as they provide sufficient germicidal effectiveness.

In use, the UV-C radiation source 132 being switched on creates UV-C radiation. Direct UV-C radiation is blocked by the air filter 131, particularly the HEPA filter stage and the housing 100. While it can be possible to perceive a blue tint in the air filter 131 through the plurality of inlet openings 105, 106 depending on the intensity of the UV-C radiation source, it causes no harm to people in the vicinity of the air purifier 10.

The curved top surface 123 of the housing 100 has the shape of an inverted cone, the vertex of the cone being located proximate to the fan 130 such that it extends into the fan cavity 120.

Figure 1C shows the airflow produced by the air purifier 10 in use according to an embodiment of the invention. When the fan 130 and the UV-C radiation source 132 are switched on, air is circulated through the air purifier 10 as follows: (i) the air is drawn into the purification cavity 121 through the first plurality of inlet openings 105 by a rotation of the fan 130, the air being filtered by the air filter 131 located in the periphery of the purification cavity 121; (ii) the filtered air is drawn through the purification cavity 121 upwardly towards the fan cavity 120 by the rotation of the fan 130, the filtered air being irradiated by the UV-C radiation source 132; (iii)the filtered and irradiated air is made to travel upwardly through the fan cavity 120 by the rotation of the fan 130; and, (iv)the filtered and irradiated air is driven from the fan cavity 130 through the first plurality of outlet openings 107 and then the second plurality of outlet openings 108, the shape of the curved top surface 123 directing the filtered and irradiated air in the shape of an upwardly and radially expanding cone.

In the case of the UV-radiation source 132 being switched off, i.e., not being operated, the above steps are carried out except that the air is not irradiated by the UV-C radiation source 132.

Figure 1D shows a radial cross-section, where a plane orthogonal to the longitudinal axis of the air purifier 10 intersects a first proximal point of the electronics cavity 122 adjacent to the purification cavity 121.

Figure 1D shows the air purifier 10 to comprise a plurality of electronic components 140 that cooperate with the microcontroller 134 shown in Figure 15. In the embodiment shown in Figure 1D, the plurality of electronic components 140 comprises an expansion board 141, a digital potentiometer 142, a pair of relays IA3, a breakout board 144 and a microcontroller accessory component such as Raspberry Pi hat 145.

The plurality of electronic components 140 also comprises a plurality of sensors such as a temperature and humidity sensor 146, a sound sensor 147 and a gas sensor 148. In particular, the gas sensor is a volatile organic compound (VOC) and eCO2 gas sensor. In use, air circulates through the electronics cavity 122 via the ventilation openings 109 allowing each sensor to detect their respective physical characteristics.

In other embodiments, the plurality of sensors may comprise any other sensor, for example it may additionally comprise a pressure sensor arranged in any suitable way.

Figure lE shows a radial cross-section where a plane orthogonal to the longitudinal axis of the air purifier 10 intersects a distal point of the electronics cavity 122 adjacent to a bottom surface 124 of the housing 100.

Figure lE shows the air purifier 10 to comprise a plurality of electronic components 150 that cooperate with other components of the air purifier 10. In the embodiment shown in Figure 1E, the plurality of electronic components 150 comprises a 3 V to 12 V power supply 151, a 5 V AC/DC convertor 152, and a pair of UV-C radiation source ballasts 154 for controlling and regulating energy delivered to the UV-C radiation source. The plurality of electronic components 150 also comprises a particulate matter sensor 153 that is able to detect PM1, PM2.5 and PM10. PM"X" means that the particulate matter sensor can detect particulate matter that has a size of "X" micron/micrometre/ pm or less in width. For example, PM2.5 means particulate matter size 2.5 micron/micrometre/pm or less in width. In use, air circulates through the electronics cavity 122 via the ventilation openings 109 allowing the particulate matter sensor 153 to detect a particulate matter concentration of the air surrounding the air purifier 10.

In other embodiments, the plurality of electronic components may comprise any other combination of components.

Figure 2 schematically shows the function of the microcontroller 134 in operating the air purifier 10. It shows the microcontroller 134 to be able to receive sensor input regarding air quality, room condition and detection of human presence as well as control instructions from any one of a smartphone, a remote server and a cloud server.

In the example shown in Figure 2, the plurality of sensors detect: (i) air quality characteristics comprising particulate matter (PM1, PM2.5 and PM10), total VOC and formaldehyde; (ii) room condition characteristics comprising humidity, temperature and light; and, (iii)human presence/absence characteristics comprising sound, motion and light.

The information sent by the air purifier 10 to the cloud server includes all the information received through the plurality of sensors. In a preferred embodiment of the invention, the information provided to the user via the cloud server shows changes in each of air quality, room condition and human presence (e.g., foot traffic) in the vicinity of the air purifier 10 over a period of time, the information including a breakdown of the characteristics detected by each respective sensor (e.g., each of PM1, PM2.5 and PM10). In alternative embodiments the information may only comprise characteristics detected by a single or any number of sensors. The information is stored in the air purifier 10 for a fixed period before being erased.

The microcontroller 134 is also shown to control the fan 130 and the UV-C radiation source 132 and to send information to a cloud server. In particular, the microcontroller 134 is shown to control the fan speed, the switching on/off of the fan, the UV-C intensity and the switching on/off of the UV-C radiation source.

The microcontroller 134 is configured to control the fan speed of fan 130 depending on the airflow that is required to provide a suitable CADR for a particular room. CADR is expressed in cubic meters per hour (m3/h) and is calculated as follows: CADR = Air Changes per hour (ACH) (h-1) x volume (m3). Air Changes per hour refers to the number of times that the total air in a room has been purified. An CADR calculated using ACH =1 may be suitable, but an ideal CADR is calculated using ACH 2.

Figure 3 shows a flowchart of an exemplary way in which the microcontroller 134 uses the information provided by the sensors to control the fan 130 and the UV-C radiation source 132.

The microcontroller 134 is configured to selectively control the fan 130 and the UV-C radiation source 132 to operate the air purifier 10 in one of a plurality of operation modes in dependence on information received from the plurality of sensors.

The plurality of operation modes comprises: a first mode ("Mode 1" or "Sleep") in which the fan 130 and the UV-C radiation source 132 are not operated; a second mode ("Mode 2" or "Idle") in which the fan 130 is operated at a fan speed which is dependent on a detected air quality and the UV-C radiation source is not operated; a third mode ("Mode 3" or "Live") in which the fan 130 is operated at a first speed and the UV-C radiation source 132 is operated at a first intensity; and, a fourth mode ("Mode 4" or "Boost") in which the fan 130 is operated at a second speed and the UV-C radiation source 132 is operated at a second intensity.

As shown in Figure 3, when the air purifier 10 is selectively controlling the fan 130 and the UV-C radiation source 132 to operate in any one of the operation modes, there are a set of conditions which will result in the microcontroller 134 selectively changing from one operation mode to another operation mode when at least one of the conditions is fulfilled. If none of the conditions for a given mode are fulfilled, there are no changes to the operation mode unless a mode has been configured to comprise an additional timer that may stop the operation of at least one component.

When the air purifier 10 is controlling the fan 130 and the UV-C radiation source 132 to operate in the first mode, the condition to be fulfilled for the microcontroller 134 to selectively change into the second mode is the particular matter concentration of particular matter above a particle size of 2.5 mm (PM2.5) being greater than 25 pg/m3.

When the air purifier 10 is controlling the fan 130 and the UV-C radiation source 132 to operate in the first mode, the conditions to be fulfilled for the microcontroller 134 to selectively change into the third mode are any one of: the PR sensor detecting a motion; the light sensor detecting a light increase; and, the sound sensor detecting a sound greater than 50 dB.

The microcontroller 134 may be configured to change the operation mode in response to a sudden increase in ambient light e.g., over seconds or milliseconds, advantageously excluding the effect of sunrise or variable weather in the increase of ambient light. When the air purifier 10 is controlling the fan 130 and the UV-C radiation source 132 to operate in the second mode, the condition to be fulfilled for the microcontroller 134 to selectively change into the first mode is the PM2.5 sensor detecting a reading lesser than 25 pg/m3.

When the air purifier 10 is controlling the fan 130 and the UV-C radiation source 132 to operate in the second mode, the conditions to be fulfilled for the microcontroller 134 to selectively change into the third mode are any one of: the PR sensor detecting a motion; and, the light sensor detecting a light increase.

When the air purifier 10 is controlling the fan 130 and the UV-C radiation source 132 to operate in the third mode, the condition to be fulfilled for the microcontroller 134 to selectively change into the fourth mode is for the PR sensor to not detect a motion during a period of time, such as 10 minutes.

When the air purifier 10 is controlling the fan 130 and the UV-C radiation source 132 to operate in the fourth mode, the conditions to be fulfilled for the microcontroller 134 to selectively change into the third mode are any one of: the PR sensor detecting a motion; and, the light sensor detecting a light increase.

When the air purifier 10 is controlling the fan 130 and the UV-C radiation source 132 to operate in the fourth mode, the condition to be fulfilled for the microcontroller 134 to selectively change into the second mode is for a period of time, such as 30 minutes, to elapse.

The air purifier having a set of conditions and the ability of sensing human presence allow it to be an automated air purifier. The air purifier can therefore be designed with only 1 physical button, which is the ON/OFF button, functioning as a plug and play product with a default automated setting and always being switched ON. Moreover, any changes to the air purifier settings or operation can be conducted wirelessly, allowing the majority of physical controls to be removed from its design. The air purifier therefore avoids having surfaces that will be touched by multiple people, reducing the chances of contagion between users and prevents changes being made to the air purifier settings due to accidental touch.

The conditions for the changing of operation modes and the operating parameters can be customised by a user to suit their needs. A user can additionally override the conditions for the changing of operation modes by selecting an operation mode. For example, in other embodiments input from other sensors, such as the gas sensor, may be used to selectively change between the first mode and the second mode.

One or more operating parameters such as the fan speed or the UV-C intensity, the operation modes and the conditions for the changing of operation modes can be modified through control instructions received by the air purifier 10 wirelessly from any one of a smartphone, a remote server and a cloud server. The modification of the parameters, the modes or the conditions for the changing of the operation modes are preferably carried out through a designated website and/or mobile application.

Table 1 below details the parameters that can be controlled by a user (shown underlined and italicised) and the ranges within which the parameters may be varied, according to an example.

Sleep Idle Live Boost Mode 1 2 3 4 Input FIR FIR FIR FIR sensors Light Light PM2.5 Light PM2.5 PM2.5 PM2.5 Sound Fan OFF ON ON, if fan speed 5-50 ON, 2nd fan speed 20-40 minute minute UV-C OFF OFF ON, rt ON, 2nd

UV-C UV-C

intensity intensity timer timer Change if PM2.5 >5-25 pg/m3, set mode 2 if FIR == ON, set mode 3 if FIR == OFF for /-5 If FIR == set mode ON, Logic if FIR == ON, set mode 3 if PM2.5 <5-25 pg/m3, set mode 1 minutes if light =sudden 3 if light == sudden if light == sudden increase set mode 4 if FIR == ON, reset 5-60 minute timer set mode 3 When timer goes, set mode 2 increase increase set mode 3 if Sound > 40- set mode 3 55dB set mode 3 Table 1 -Operating modes In a preferred embodiment of the invention, the microcontroller 134 is configured to control the fan 130 to operate at a first fan speed when operating in the third mode and to operate at a second fan speed when operating in the fourth mode, as shown in Table 1. The microcontroller 134 is configured to operate the fan 130 at a first fan speed that will provide an ideal CADR for a particular room, or as close to an ideal CADR as it is possible while maintaining the noise level of the air purifier 10 below a noise level. The noise level is preferably in a range between 40 and 65 dB, more preferably 50dB. The value of the second fan speed is preferably at least 1.5 times greater than the value of the first fan speed.

For example, the ideal CADR for a room of 180 m3 would be 360 m3/h or 100 litres per second (assuming an empty room) may be achieved with a fan speed of 6000 rpm. In certain embodiments a user may input room information and the microcontroller 134 will calculate the suitable CADR and corresponding first fan speed and second fan speed. In alternative embodiments, the air purifier may provide a CADR calculated with any ACH value. The fan 130 is configured to operate at a first speed ranging between 1500 rpm to 9100 rpm. The fan is more preferably configured to operate at a first speed ranging between 5000 rpm and 7000 rpm. The fan is further preferably configured to operate at a first speed that is about 6000 rpm.

In a preferred embodiment of the invention, the microcontroller is further configured to control the UV-C radiation source 132 to operate at a first intensity when operating in the third mode and to operate at a second intensity when operating in the fourth mode. The value of the second intensity is preferably at least twice the value of the first intensity. For example, the UV-C radiation source 132 may be configured to operate at 3559 itW/Cm2 in the third mode and 7118 iiW/cm2 in the fourth mode.

In further embodiments, other operating parameters may be modifiable. For example, a user may be able to disable any one of the plurality of sensors or use the PM1 readings instead of the PM2.5 readings for changing operation modes.

Claims

CLAIMS1. An air purifier comprising: a housing; a fan for drawing air through the housing; an air filter; a UV-C radiation source for disinfecting air drawn through the housing; a plurality of sensors configured to detect at least one characteristic of air quality and at least one characteristic of human presence or absence; and, a microcontroller configured to selectively control the fan and the UV-C radiation source to operate the air purifier in one of a plurality of operation modes in dependence on information received from the plurality sensors.
2. The air purifier of claim 1, wherein the microcontroller is configured to selectively control the UV-C radiation source to operate at a plurality of different UV-C radiation intensities.
3. The air purifier of claim 1 or claim 2, wherein the plurality of operation modes 20 comprises: a first mode in which the fan and the UV-C radiation source are not operated; a second mode in which the fan is operated at a fan speed which is dependent on a detected air quality; a third mode in which the fan is operated at a first speed and the UV-C radiation source is operated at a first intensity; and, a fourth mode in which the fan is operated at a second speed and the UV-C radiation source is operated at a second intensity.
4. The air purifier of claim 3, wherein each of the first speed and the first intensity is lower than the second speed and the second intensity, respectively.
5. The air purifier of claim 3 or claim 4, wherein the first speed provides a minimum Clean Air Delivery Rate (CADR) and the value of the second speed is at least 1.5 times greater than the value of the first speed.
6. The air purifier of and of claims 3 to 5, wherein the microcontroller is configured to selectively change the operation mode from any one of the first mode, the second mode or the fourth mode to the third mode when the plurality of sensors detects at least one characteristic of human presence.
7. The air purifier of claim 6, wherein the plurality of sensors comprises a PIR sensor and/or a light sensor and wherein the at least one characteristic of human presence is a motion and/or an increase in ambient light.
8. The air purifier of any one of claims 3 to 7, wherein the microcontroller is configured to selectively change the operation mode from the first mode to the second mode when a detected air quality is below a threshold value, and to selectively change the operation mode from the second mode to the first mode when a detected air quality is above a threshold value.
9. The air purifier of claim 8, wherein the plurality of sensors comprises a particulate matter sensor and the at least one characteristic of air quality is a detected mass concentration of particulate matter in the air.
10. The air purifier of any one of claims 3 to 9, wherein the microcontroller is configured to selectively change the operation mode from the third mode to the fourth mode when no motion is detected for a period of time, and to selectively change the operation mode from the fourth mode to the second mode after a period of time.
11. The air purifier of any one of claims 3 to 10, wherein the plurality of sensors comprises a microphone and the at least one characteristic of human presence is a detected sound above a threshold value, and wherein the microcontroller is configured to selectively change the operation mode from the first mode to the third mode when human presence is detected.
12. The air purifier of any one of claims 3 to 11, wherein in the third operation mode the air purifier operates the fan and the UV-C radiation source for a period of time, the period of time being reset when a motion is detected.
13. The air purifier of any one of the preceding claims, wherein the housing defines a fan cavity and an air purification cavity, the fan cavity being configured to receive the fan and the purification cavity being configured to receive the air filter and the UV-C radiation source.
14. The air purifier of claim 13, wherein the fan cavity is located around a longitudinal axis above the purification cavity, and the fan is configured to draw air through inlet openings in a lower side wall of the housing into the purification cavity.
15. The air purifier of claims 13 or 14, wherein the housing comprises an upper side wall having a plurality of outlet openings for directing air driven from the fan cavity.
16. The air purifier of claim 15, wherein the outlet openings are collectively configured to direct a cone of air upwardly away from the housing.
17. The air purifier of any one of the preceding claims, wherein the housing is substantially cylindrical.
18. The air purifier of any one of the preceding claims, wherein the UV-C radiation source is arranged proximate to the air filter to irradiate air that has passed through the air filter.
19. The air purifier of any one of the preceding claims, wherein the wavelength of the UV-C radiation emitted by the UV-C radiation source is within the range of 100nm and 280nm, more preferably around 253.7nm.
20. The air purifier of any one of the preceding claims, wherein the UV-C radiation source comprises at least two mercury vapour bulbs, each preferably configured to produce an intensity of 10pW/m2 at a distance of lm.
21. The air purifier according to any one of the preceding claims, wherein the air filter is a cylindrical filter, and preferably a 3-stage filter incorporating a HEPA filter stage and an activated charcoal stage.
22. The air purifier of any one of the preceding claims, which is Internet of Things (IoT) enabled.
23. The air purifier of any one of the preceding claims, wherein the microcontroller is further configured to communicate wirelessly with one or more of a smartphone, remote server and cloud server to provide a data feed from the plurality of sensors and to receive control instructions.
24. The air purifier of claim 23, wherein the data feed comprises information metrics on the air quality and human presence over a period of time.
25. The air purifier of claim 23 or claim 24, wherein the microcontroller is responsive to control instructions to modify one or more operating parameters of the air purifier.
26. The air purifier of any one of the preceding claims, wherein the air purifier is a compact turbo air purifier.