Abstract: An air purifier according to the present disclosure includes: a memory for storing a flow rate/pressure differential correlation graph with regard to each filter utilization state; a pressure differential sensor for measuring a pressure differential, which is a difference in pressure between the front and rear ends of the filter; and a filter replacement time management unit for determining the time to replace the filter according to a result of matching a pressure differential of the filter, which is measured by the pressure differential sensor at a preset cycle, and the flow rate of air flowing into the filter during pressure differential measurement with the flow rate/pressure differential correlation graph for each utilization state.

Abstract: An air purifier according to an embodiment of the present invention may comprise: a memory for storing a flow rate/pressure differential correlation graph with regard to each filter utilization state; a pressure differential sensor for measuring a pressure differential, which is a difference in pressure between the front and rear ends of the filter; and a filter replacement time management unit for determining the time to replace the filter according to a result of matching a pressure differential of the filter, which is measured by the pressure differential sensor at a preset cycle, and the flow rate of air flowing into the filter during pressure differential measurement with the flow rate/pressure differential correlation graph for each utilization state.

Abstract: The present invention relates to a robot cleaner system and a method of controlling a robot cleaner. When cleaning start information is received, a control unit (17) of the robot cleaner scans one cleaning area (30), thus calculating a cleaning time. The control unit performs cleaning of the cleaning area. When a signal transmitted from a transmission device (20) is received, the control unit detects which transmitter transmitted the signal. The control unit determines whether a time for which a signal transmitted from a same transmitter has been received is equal to or longer than a preset period. If the time is shorter than the preset period, the control unit continuously performs cleaning. If the time for which the transmitted signal has been received is equal to or longer than the preset period, the control unit moves the robot cleaner until a signal transmitted from another transmitter is received.