A refrigerator including a compressor, a condenser, and an expansion unit that constitute a refrigeration cycle, an evaporator that evaporates a refrigerant that has passed through the expansion unit, a heating unit that provides heat for defrosting the evaporator, and a frost sensor unit that is provided at one side of the evaporator to sense the amount of frost on the evaporator, the frost sensor unit including a sound-source transmitting unit that generates a sound-source of a first volume to the evaporator, and a sound-source receiving unit that receives a sound-source of a second volume formed after the sound-source transmitted by the sound-source transmitting unit reflects from or passes through the evaporator, and a controller that controls the heating unit to generate heat, when the difference between the first volume and the second volume reaches a predetermined value.

A refrigerator including a compressor, a condenser, and an expansion unit that constitute a refrigeration cycle, an evaporator that evaporates a refrigerant that has passed through the expansion unit, a heating unit that provides heat for defrosting the evaporator, and a frost sensor unit that is provided at one side of the evaporator to sense the amount of frost on the evaporator, the frost sensor unit including a sound-source transmitting unit that generates a sound-source of a first volume to the evaporator, and a sound-source receiving unit that receives a sound-source of a second volume formed after the sound-source transmitted by the sound-source transmitting unit reflects from or passes through the evaporator, and a controller that controls the heating unit to generate heat, when the difference between the first volume and the second volume reaches a predetermined value.

A refrigerating and air-conditioning apparatus that performs defrosting operation, the refrigerating and air-conditioning apparatus including: a refrigerant circuit in which a compressor, a first heat exchanger, an expansion device, a second heat exchanger, and a four-way valve are connected to each other by pipes to allow refrigerant to circulate through the refrigerant circuit; a temperature sensor configured to measure a temperature of the compressor; and a heat generation control unit configured to increase a temperature of the compressor when the heat generation control unit detects a decrease in a value measured by the temperature sensor in defrosting operation performed on the first heat exchanger.

A refrigerating and air-conditioning apparatus that performs defrosting operation, the refrigerating and air-conditioning apparatus including: a refrigerant circuit in which a compressor, a first heat exchanger, an expansion device, a second heat exchanger, and a four-way valve are connected to each other by pipes to allow refrigerant to circulate through the refrigerant circuit; a temperature sensor configured to measure a temperature of the compressor; and a heat generation control unit configured to increase a temperature of the compressor when the heat generation control unit detects a decrease in a value measured by the temperature sensor in defrosting operation performed on the first heat exchanger.

A refrigerator is configured such that a controller may control the frost detecting operation to be differently performed on the basis of at least one of a room temperature and a set reference temperature. Thus, precise frosting detection may be performed and power consumption due to the frosting detection may be minimized, and power consumption efficiency may be improved.

A refrigerator is configured such that a controller may control the frost detecting operation to be differently performed on the basis of at least one of a room temperature and a set reference temperature. Thus, precise frosting detection may be performed and power consumption due to the frosting detection may be minimized, and power consumption efficiency may be improved.

The present invention provides a control method of a refrigerator, comprising: a first defrosting step of defrosting an evaporator and terminating the defrosting when the evaporator reaches a first temperature; a step of detecting pressure difference by means of a differential pressure sensor for measuring pressure difference between a first thru-hole, disposed between the evaporator and an inlet through which air flows in from a storage compartment, and a second thru-hole disposed between the evaporator and an outlet through which the air is discharged into the storage compartment; and a second defrosting step of additionally defrosting the evaporator if the measured pressure difference is greater than a configured pressure.

The present invention provides a control method of a refrigerator, comprising: a first defrosting step of defrosting an evaporator and terminating the defrosting when the evaporator reaches a first temperature; a step of detecting pressure difference by means of a differential pressure sensor for measuring pressure difference between a first thru-hole, disposed between the evaporator and an inlet through which air flows in from a storage compartment, and a second thru-hole disposed between the evaporator and an outlet through which the air is discharged into the storage compartment; and a second defrosting step of additionally defrosting the evaporator if the measured pressure difference is greater than a configured pressure.

A system includes a conductive element. The system also includes a resonant circuit having a sensing capacitor arranged such that an amount of target material in a sensing zone of the sensing capacitor changes a capacitance of the sensing capacitor, wherein the conductive element is electrically isolated from at least part of the resonant circuit. The system also includes a resonant circuit analyzer configured to detect a resonant frequency of the resonant circuit and to output a digitized analyzer signal based on the resonant frequency. The system also includes a processor configured to receive the digitized analyzer signal, to determine a target material estimate based on the digitized analyzer signal, and to output the target material estimate or a signal derived from the target material estimate to an output device.

A system includes a conductive element. The system also includes a resonant circuit having a sensing capacitor arranged such that an amount of target material in a sensing zone of the sensing capacitor changes a capacitance of the sensing capacitor, wherein the conductive element is electrically isolated from at least part of the resonant circuit. The system also includes a resonant circuit analyzer configured to detect a resonant frequency of the resonant circuit and to output a digitized analyzer signal based on the resonant frequency. The system also includes a processor configured to receive the digitized analyzer signal, to determine a target material estimate based on the digitized analyzer signal, and to output the target material estimate or a signal derived from the target material estimate to an output device.