Laundry drying machine and control method of laundry drying machine

Abstract

The present invention relates to a laundry drying machine including a cabinet, a drum rotatably installed in the cabinet to accommodate articles to be dried, and an electric field generator spaced apart from the drum and generating an electric field inside the drum when supplied with power. The electric field generator includes a positive electrode spaced apart from the drum, fixed to the cabinet, and applying an electric field to the articles to be dried accommodated in the drum, a power supply unit supplying power to the positive electrode, and a matcher provided in the cabinet and matching a power source impedance with a load side impedance. In a state where the power is stopped being applied to the positive electrode, the drum rotates at a preset agitating rotational speed, and the agitating rotational speed is greater than 0 and less than 50 rpm, thereby having an effect that the articles to be dried can slide along an inner circumferential surface of the drum without falling.

Description

TECHNICAL FIELD

[0001] The present application relates to a laundry drying machine and a control method thereof, and more particularly, to a laundry drying machine capable of generating high frequency and drying a subject to be dried by dielectric heating, and a control method thereof. BACKGROUND

[0002] In recent years, a clothes treating apparatus performing a drying cycle to remove moisture from clothes has been developed. The conventional clothes treating apparatus supplies hot air to a drum in which clothes are accommodated to dry the clothes, thereby greatly reducing a drying time of the clothes and sterilizing and disinfecting the clothes.

[0003] However, this type of drying machine uses heat transferred from the heated air to increase the temperature of water contained in the clothes to cause evaporation of the water. Since the heat is transferred from the air having a low specific heat to the water having a high specific heat, the actual temperature of the water does not increase much compared to the temperature of the heated air, and its drying performance is low compared to the consumed energy.

[0004] In addition, in order for the water contained in the clothes to reach an evaporation temperature, the temperature in the drum must reach a high temperature of 100 degrees Celsius or more, and thus there is a problem in that the high-temperature air comes into contact with the clothes, causing denaturation and damage to the clothes.

[0005] In addition, such a drying machine is also equipped with an exhaust system for discharging moisture evaporated from the clothes to the outside of the drying machine. In this case, since the heated air is continuously discharged, the temperature inside the drum inevitably decreases, and the operation time of the heater also increases, and thus there is a problem in that energy consumption and drying time increase.

[0006] In order to solve this problem, a high frequency (RF) laundry drying machine has been developed, which vibrates and heats moisture absorbed in the clothes.

[0007] In the high frequency (RF) laundry drying machine, in order to solve the overheating problem when the RF power is used for a long time, and in order to uniformly heat the subject to be dried by mixing the subject to be dried, there is a process of rotating the drum at only 50 rpm in the absence of an RF power supply.

[0008] However, in this process, the subject to be dried rotates in the drum by means of centrifugal force and falls down due to the effect of gravity during the rotation. Therefore, there is a problem in that the subject to be dried shrinks due to such mechanical forces.

[0009] US patent US 9200402B discloses a dielectric heating type laundry dryer.

[0010] In this dryer, a negative electrode and a positive electrode are rotatably provided, and when RF power of a predetermined frequency is applied, an electric field is generated to heat moisture contained in clothes.

[0011] On the other hand, since both the negative electrode and the positive electrode are provided in a rotating form, in order to form a constant electric field, the drum must be substantially stopped.

[0012] However, when the internal temperature of the object to be dried rapidly increases as described above, there is a problem that local overheating occurs inside the object to be dried. In particular, when the object to be dried is a dyed synthetic fiber, there is a problem of color transfer due to local overheating. In the case of a synthetic fiber, if the temperature exceeds 50 degrees Celsius, color transfer can occur.

[0013] Meanwhile, US patent US 9447537B discloses a laundry dryer that uses electrodes to dielectrically heat an object to be dried.

[0014] In the above invention, the positive electrode is fixed, and the drum as a negative electrode is provided in a rotatable state.

[0015] In the above invention, when the drying process starts, RF power is applied to the positive electrode while the drum is stopped. While the drum is stopped, impedance matching is easy, and after impedance matching, continuous heating is possible, which is effective for rapidly heating moisture contained in the object to be dried.

[0016] However, even in this case, there is a problem that the internal temperature of the object to be dried rapidly increases, causing local overheating.

[0017] In this case, in order to prevent local overheating inside the clothes, after heating the object to be dried for 90 seconds, the supply of RF current is stopped, and the drum is rotated for 5 seconds to mix the object to be dried.

[0018] However, in this method, since dielectric heating is performed again in a state where heat inside the object to be dried is not sufficiently discharged, there is a problem that the internal temperature of the object to be dried continuously increases as the drying cycle progresses.

[0019] Further, in this method, the matcher must perform impedance matching in less than 7 seconds in order to supply RF power again, and in this process, power consumption can occur, so there is a problem in that the entire drying time increases.

[0020] Further, in the case of heating after sufficiently discharging internal heat, the energy and time required for dielectric heating again are large, so there is a problem in that drying efficiency decreases.

[0021] Further, in the process of mixing the articles to be dried, the articles to be dried can move downward due to the centrifugal force of the drum, and the clothes can shrink.

[0022] On the other hand, Korean Publication Patent KR 2018-0085201A discloses a dryer that simultaneously performs RF drying and hot air drying.

[0023] In such a dryer, a negative electrode and a positive electrode are rotatably provided, and when RF power of a predetermined frequency is applied, an electric field is generated to heat moisture contained in the clothes. Therefore, in order to form a constant electric field, the drum must be substantially stopped.

[0024] Accordingly, the dryer also stops the drum to perform heating, and repeats the operation of rotating the drum to prevent the clothes from being locally overheated, thereby increasing energy consumption and drying time.

[0025] The dryer can perform hot air drying while rotating the drum to solve the problem of increased drying time. However, when dielectric heating and hot air drying are simultaneously performed, power consumption can be very large.

[0026] Further, while the articles to be dried are heated in a dielectric heating manner inside, the articles to be dried are also heated in a hot air drying manner outside, thereby causing damage to the articles to be dried.

[0027] Therefore, it is necessary to develop a technology capable of minimizing energy consumption while shortening drying time.

[0028] On the other hand, Korean Publication Patent KR 2007-0056287A discloses a hot air type dryer. In this dryer, the drum is constantly rotated at a rotational speed of 50 rpm in order to uniformly supply hot air to the articles to be dried during the drying process.

[0029] In this case, the articles to be dried are rotated by centrifugal force and move upward in the drum and fall down by the action of gravity. In this case, the drying performance can be improved by increasing the contact area with the hot air while the articles to be dried fall, but there is a problem in that the articles to be dried are shrunk. SUMMARY

[0030] TECHNICAL PROBLEM

[0031] The present invention aims to improve the problems of the conventional laundry dryer and the control method of the laundry dryer as described above, and an object of the present invention is to provide a laundry dryer and a control method of the laundry dryer capable of preventing color transfer in the articles to be dried.

[0032] Another object of the present invention is to provide a laundry dryer and a method of controlling the same, which can prevent local overheating of the articles to be dried.

[0033] Another object of the present invention is to provide a laundry dryer and a control method of the laundry dryer, which can heat the articles to be dried accommodated in the drum while the drum rotates in a dielectric heating type dryer.

[0034] Another object of the present invention is to provide a laundry dryer and a control method of the laundry dryer, which can improve the drying efficiency of a dielectric heating type dryer requiring a large amount of energy and time to perform dielectric heating.

[0035] Another object of the present invention is to provide a laundry dryer and a method of controlling the same, which can minimize energy consumption during drying.

[0036] Another object of the present invention is to provide a laundry dryer and a control method of the laundry dryer, which can prevent color transfer of the articles to be dried regardless of the size of the laundry dryer.

[0037] Another object of the present invention is to provide a laundry dryer and a method of controlling the same, which can prevent damage to a matcher or the like due to reflected waves generated according to rotation of the drum.

[0038] Another object of the present invention is to provide a laundry dryer and a control method of the laundry dryer, which can save time and energy required for impedance matching.

[0039] Another object of the present invention is to provide a laundry dryer and a control method of the laundry dryer, which can prevent the articles to be dried from falling during mixing of the articles to be dried.

[0040] Another object of the present application is to provide a laundry drying machine and a method of controlling the same, which can reduce shrinkage of an article to be dried and provide a similar degree of shrinkage to natural drying.

[0041] Technical Solution

[0042] To achieve the above object, a laundry drying machine according to the present application can include a cabinet, a drum rotatably installed in the cabinet to accommodate an article to be dried, an electric field generator spaced apart from the drum and generating an electric field inside the drum when powered, and an exhaust duct discharging air inside the drum.

[0043] The electric field generator can include a positive electrode spaced apart from the drum, fixed to the cabinet, and applying an electric field to the article to be dried accommodated in the drum.

[0044] The electric field generator can further include a power supply unit (power supply unit) supplying power (power) to the positive electrode.

[0045] The electric field generator can further include a matcher disposed in the cabinet and matching an impedance of a power source with an impedance of a load side.

[0046] In this case, when power (electric power) is applied to the positive electrode, the drum can rotate.

[0047] When power is applied to the positive electrode, the drum rotates at a predetermined drying rotational speed, and when the application of power to the positive electrode is stopped, the drum rotates at a predetermined agitation rotational speed.

[0048] The drying rotational speed can be less than the agitation rotational speed.

[0049] The positive electrode can be formed in an arc shape that encloses a predetermined angle range with the rotational axis of the drum as a center.

[0050] In this case, while power is applied to the positive electrode, the drum can rotate at a rotational speed of more than times the angle (rad) formed by the positive electrode and less than 7 rpm.

[0051] The drum can include a drum body formed in a cylindrical shape and accommodating the article to be dried therein, and a notch part connected to the drum body and bent inward from an outer peripheral surface of the drum body.

[0052] The notch part can include a connection part formed in a ring shape and connected to the drum body, and a positive electrode receiving part bent inward in a radial direction at the connection part and forming a space for accommodating the positive electrode.

[0053] The positive electrode can be spaced apart from the notch portion at a predetermined interval, and can be formed in a circular arc shape concentric with the notch portion.

[0054] The matcher can continuously match the power source impedance and the impedance of the load side while the drum is rotated at a drying rotational speed.

[0055] The laundry dryer according to an embodiment of the present application can further include a drum motor providing a driving force to rotate the drum, and a control unit disposed inside the cabinet and controlling the drum motor and the electric field generator.

[0056] In this case, the control unit can simultaneously operate the matcher and the drum motor.

[0057] The control unit can measure a temperature of the laundry to be dried, and operate the drum motor to maintain the temperature of the laundry to be dried at 50 degrees Celsius or less.

[0058] The drum can further include at least one riser disposed at an inner circumferential surface of the drum body and formed to protrude toward a center of the drum body.

[0059] The riser can contact the laundry to be dried at least once while power is applied to the positive electrode.

[0060] To achieve the above object, in a control method of a laundry dryer including a drum accommodating laundry to be dried and a positive electrode spaced apart from the drum to generate an electric field in the drum, the control method of the laundry dryer according to the present application can include a drying step of applying power to the positive electrode and rotating the drum at a preset drying rotational speed for a preset drying time, and an agitation step of cutting off the power application to the positive electrode and rotating the drum at a preset agitation rotational speed for a preset agitation time.

[0061] The drying rotational speed and the agitation rotational speed in the drying step can be different.

[0062] The drying rotational speed in the drying step can be less than the agitation rotational speed.

[0063] In the drying step, the drum can be rotated, and the matcher can be operated to continuously match the power source impedance and the impedance of the load side.

[0064] In the drying step, the drying time can be 80 seconds or more and 100 seconds or less.

[0065] In the agitation step, the agitation time can be 3 seconds or more and 7 seconds or less.

[0066] The control method of the laundry dryer according to the present application can further include a load sensing step of rotating the drum to sense a load of the laundry to be dried before the drying step.

[0067] The drying rotation speed in the drying step can be less than the rotation speed of the drum in the load sensing step.

[0068] In the drying step, the drying rotation speed can be set in proportion to an angle range in which the arc-shaped positive electrode is disposed with the rotational axis of the drum as a center.

[0069] In the drying step, the drying rotation speed can be a multiple of an angle (rad) in which the arc-shaped positive electrode is disposed with the rotational axis of the drum as a center. or more.

[0070] In the drying step, the drying rotation speed can be 0 or more and 7 rpm or less.

[0071] To achieve the above object, a laundry dryer according to the present application can include a cabinet, a drum rotatably installed in the cabinet to accommodate articles to be dried, and an electric field generator spaced apart from the drum and generating an electric field in the drum when power is supplied.

[0072] The electric field generator can include a positive electrode spaced apart from the drum, fixed to the cabinet, and applying an electric field to the articles to be dried accommodated in the drum, a power supply unit applying power to the positive electrode, and a matcher disposed in the cabinet and matching an impedance of a power source with an impedance of a load side.

[0073] In a state in which the power is not applied to the positive electrode, the drum is rotated at a preset agitation rotation speed, and the agitation rotation speed can be greater than 0 and less than 50 rpm.

[0074] In this case, a value obtained by multiplying a radius of the drum by a square of the agitation rotation speed (rad / s) can be 0.27 times or less the magnitude of the acceleration due to gravity.

[0075] When the power is applied to the positive electrode, the drum can be rotated at a preset drying rotation speed.

[0076] The agitation rotation speed can be greater than the drying rotation speed.

[0077] The agitation rotation speed can be greater than 0 and less than 30 rpm.

[0078] Accordingly, when the drum is rotated at the preset agitation rotation speed, the articles to be dried can slide along an inner circumferential surface of the drum.

[0079] To achieve the above object, in a control method including a drum accommodating articles to be dried and a positive electrode spaced apart from the drum to generate an electric field in the drum, a control method of a laundry dryer according to the present application can include a drying step of applying power to the fixed positive electrode and rotating the drum, and an agitation step of cutting off the power applied to the positive electrode and rotating the drum.

[0080] In the agitating step, the drum is rotated at a preset agitating rotational speed, which can be greater than 0 and 30 rpm or less.

[0081] The square of the agitating rotational speed can be set to be inversely proportional to the radius of the drum.

[0082] A value obtained by multiplying the radius of the drum by the square of the agitating rotational speed (rad / s) can be 0.27 times or less the magnitude of the gravitational acceleration.

[0083] In the agitating step, the drum is rotated for a preset agitating time, and the agitating time can be 3 seconds or more and 7 seconds or less.

[0084] In the drying step, the drum can be rotated at a preset drying rotational speed, and the drying rotational speed can be less than the agitating rotational speed.

[0085] In the drying step, the drying rotational speed can be greater than 0 and 7 rpm or less.

[0086] The control method of the laundry dryer according to the present application can further include a load sensing step of rotating the drum to sense a load of the articles to be dried before the drying step.

[0087] In this case, in the load sensing step, the drum can be rotated at the agitating rotational speed.

[0088] To achieve the above object, a laundry dryer according to the present application can include a cabinet, a drum rotatably installed in the cabinet to accommodate articles to be dried, an electric field generator spaced apart from the drum and generating an electric field within the drum when power is applied, and an exhaust duct discharging air within the drum.

[0089] The electric field generator can include a positive electrode spaced apart from the drum, fixed to the cabinet, and applying an electric field to the articles to be dried accommodated in the drum, a power supply unit supplying power (electricity) to the positive electrode, and a matcher provided in the cabinet and matching a power source impedance and a load side impedance.

[0090] In this case, when the reflectivity of the electric field exceeds a predetermined ratio, the rotational speed of the drum can be reduced.

[0091] When the reflectivity of the electric field is less than or equal to the predetermined ratio, the electric field generator can increase power (electricity) applied to the positive electrode.

[0092] When the reflectivity of the electric field exceeds the predetermined ratio, the rotational speed of the drum can be reduced by 10%.

[0093] When the power applied to the positive electrode corresponds to 20% of the drying power, and the reflectance of the electric field is less than or equal to the predetermined ratio, the electric field generator can apply power corresponding to 50% of the drying power to the positive electrode.

[0094] When the power applied to the positive electrode corresponds to 20% of the drying power, and the reflectance of the electric field is less than or equal to the predetermined ratio, the electric field generator can apply power corresponding to 50% of the drying power to the positive electrode.

[0095] When the power applied to the positive electrode corresponds to 50% of the drying power, and the reflectance of the electric field is less than or equal to the predetermined ratio, the electric field generator can apply power corresponding to 100% of the drying power to the positive electrode.

[0096] When the power corresponding to the preset drying power is applied to the positive electrode, and the reflectance of the electric field reflected from the article to be dried is less than or equal to the predetermined ratio, the drum can maintain the rotational speed.

[0097] When the power is applied to the positive electrode, the drum can rotate.

[0098] To achieve the above object, in a control method of a laundry dryer including a drum accommodating an article to be dried and a positive electrode spaced apart from the drum to generate an electric field in the drum, the control method of the laundry dryer according to the present application can include a drying step of applying power to the fixed positive electrode and rotating the drum, and an agitation step of cutting off the power application to the positive electrode and rotating the drum.

[0099] In the drying step, when the reflectance of the electric field exceeds the predetermined ratio, the rotational speed of the drum can be decreased, and when the reflectance of the electric field is less than or equal to the predetermined ratio, the power applied to the positive electrode can be increased.

[0100] The drying step can include a drying entry step of applying a preset startup power to the positive electrode and rotating the drum at a preset startup rotational speed, and a rotational speed maintaining step of applying a preset drying power to the positive electrode and maintaining the rotational speed of the drum.

[0101] In the drying step, when the reflectance of the electric field exceeds the predetermined ratio after the drying entry step, the rotational speed of the drum can be decreased.

[0102] The drying step can further include a first power increase step of increasing the power applied to the positive electrode to 20% of the drying power when the reflectance of the electric field is less than or equal to the predetermined ratio after the drying entry step.

[0103] In the drying step, after the first power increase step, when the reflectance of the electric field exceeds the predetermined ratio, the rotational speed of the drum can be decreased.

[0104] The drying step can further include a second power increase step of increasing the power applied to the positive electrode to 50% of the drying power when the reflectance of the electric field is less than or equal to the predetermined ratio after the first power increase step.

[0105] In the drying step, the rotational speed of the drum can be decreased when the reflectance of the electric field exceeds the predetermined ratio after the second power increase step.

[0106] The drying step can further include a third power increase step of increasing the power applied to the positive electrode to the drying power when the reflectance of the electric field is less than or equal to the predetermined ratio after the second power increase step.

[0107] In the drying step, the rotational speed of the drum can be decreased when the reflectance of the electric field exceeds the predetermined ratio after the third power increase step.

[0108] Advantageous Effects

[0109] As described above, the laundry dryer and the control method of the laundry dryer according to the present application can achieve an effect of preventing color transfer in the laundry to be dried by maintaining the internal temperature of the laundry to be dried at 50 degrees or less.

[0110] Further, it has an effect of preventing local overheating of the laundry to be dried when the laundry to be dried is mixed by rotation of the drum.

[0111] Further, it has an effect of heating the laundry to be dried accommodated in the drum while the drum is rotated at a low speed in a state in which the positive electrode is fixed in the dielectric heating type dryer.

[0112] In the dielectric heating type dryer in which a large amount of energy and time is consumed for dielectric heating, it has an effect of improving drying efficiency by rotating the drum even in a state in which power is applied to the positive electrode.

[0113] Further, it has an effect of minimizing energy consumption by minimizing the rotational speed of the drum in the drying process and the agitation calibration.

[0114] Further, it has an effect of preventing color transfer of the laundry to be dried regardless of the size of the laundry dryer by providing the minimum rotational speed of the drum proportional to the angle around the positive electrode and the drum.

[0115] Further, it has an effect of preventing damage to a matching device or the like due to a reflected wave by controlling the rotational speed of the drum and the RF power to decrease the reflectance of the electric field.

[0116] Further, since the drying process can be started immediately without a separate impedance matching time, there is an effect of saving time and energy required for impedance matching.

[0117] Further, there is an effect in that, during mixing of the articles to be dried, by setting the rotational speed range of the drum, the articles to be dried can slide along the inner circumferential surface of the drum without falling.

[0118] Further, there is also an effect of reducing shrinkage of the articles to be dried due to mechanical force by preventing falling movement of the articles to be dried. BRIEF DESCRIPTION OF DRAWINGS

[0119] Figure 1 is a view for explaining the appearance of a laundry dryer according to an embodiment of the present application.

[0120] Figure 2 is a view of Figure 1 from another angle.

[0121] Figure 3 is a sectional view taken along Figure 2 the center line A-A.

[0122] Figure 4 is a sectional view taken along Figure 2 the center line B-B.

[0123] Figure 5 is a partial enlarged view of Figure 4 part A.

[0124] Figure 6 is a view of a state in which a front panel, an upper panel, and a side panel in a laundry dryer according to an embodiment of the present application are disassembled.

[0125] Figure 7 is a rear view of a state in which a rear panel in a laundry dryer according to an embodiment of the present application is disassembled.

[0126] Figure 8 is a front view of a state in which a cabinet in a laundry dryer according to an embodiment of the present application is disassembled.

[0127] Figure 9 is a front view of a state in which a notch portion in a laundry dryer according to an embodiment of the present application is partially disassembled.

[0128] Figure 10 is a front view for explaining an electric field generator in a laundry dryer according to an embodiment of the present application.

[0129] Figure 11 is a perspective view showing an electric field generator in a laundry dryer according to an embodiment of the present application.

[0130] Figure 12 is a block diagram for explaining a control configuration scheme in a laundry drying machine according to an embodiment of the present application.

[0131] Figure 13 is a flowchart showing a procedure of a control method of a laundry drying machine according to an embodiment of the present application.

[0132] Figure 14 is a graph showing a temperature change of an object to be dried in a conventional dielectric heating type laundry drying machine.

[0133] Figure 15 is a graph showing a temperature change of an object to be dried when a control method of a laundry drying machine according to an embodiment of the present application is applied.

[0134] Figure 16 is a flowchart for explaining a procedure of controlling a rotational speed of a drum and RF power for impedance matching in a control method of a laundry drying machine according to an embodiment of the present application during a drying process.

[0135] Figure 17 is a graph showing a difference in shrinkage rate according to time when a control method of a laundry drying machine according to an embodiment of the present application is applied. DETAILED DESCRIPTION

[0136] Hereinafter, preferred embodiments of the present application will be described in detail with reference to the accompanying drawings.

[0137] As the present application can be varied and modified in various ways, embodiments are illustrated in the drawings and described in detail in the specific description. This is not intended to limit the present application to particular embodiments, but to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present application.

[0138] In describing the present application, terms such as first, second, etc. can be used to describe various components, but the components can not be limited by the terms. The above terms are used only to distinguish one component from another component. For example, a first component can be referred to as a second component, and likewise, a second component can be referred to as a first component without departing from the scope of the present application.

[0139] The term "and / or" can include a combination of a plurality of associated listed items or any one of a plurality of associated listed items.

[0140] When a component is described as being "connected" or "in contact" with another component, it may be directly connected or in contact with the other component, but it can be understood that other components may exist between the two. On the other hand, when a component is described as being "directly connected" or "directly in contact" with another component, it can be understood that there are no other components between the two.

[0141] The terminology used in this application is for describing specific embodiments only and is not intended to limit the invention. Singular expressions may include plural expressions unless the context clearly specifies otherwise.

[0142] In this application, terms such as “comprising” or “having” are intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and are to be understood as not precluding the possibility of the presence or addition of one or more other features or numbers, steps, operations, components, parts or combinations thereof.

[0143] Unless otherwise defined, all terms used herein (including technical or scientific terms) may have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms such as those defined in common dictionaries may be interpreted as having the meaning consistent with the relevant technical context, and should not be interpreted in an ideal or overly formal sense unless expressly defined in this application.

[0144] Furthermore, the following embodiments are provided to explain more completely to those skilled in the art. For clarity, the shape and size of the elements in the figures may be exaggerated.

[0145] Figure 1 The diagram shows a view for explaining the appearance of a clothes dryer according to an embodiment of the present invention. Figure 2 Show Figure 1 A view taken from another angle. Figure 3 Show along Figure 2 A sectional view taken along the centerline AA. Figure 4 Show along Figure 2 A sectional view taken along the center line BB. Figure 5 Show Figure 4 A magnified view of part A. Figure 6 This view shows a clothes dryer according to an embodiment of the present invention with the front panel, top panel, and side panels removed. Figure 7 A rear view showing a clothes dryer according to an embodiment of the present invention with the rear panel removed. Figure 8 A front view showing the housing of a clothes dryer according to an embodiment of the present invention is shown with the housing disassembled.

[0146] like Figures 1 to 8As shown, the cabinet 10, which forms an outer body of the laundry dryer 1, includes a front panel 11 constituting a front surface, a rear panel 12 constituting a rear surface, a pair of side panels 13 constituting side surfaces, an upper panel 14 constituting an upper surface, and a lower panel 15 constituting a lower surface.

[0147] The front panel 11 can be provided with an inlet 111 provided to communicate with a drum 20 described below, and a door 112 rotatably coupled to the cabinet 10 to open and close the inlet 111.

[0148] A control panel 117 is provided on the front panel 11.

[0149] The control panel 117 can be provided with an input unit 118 receiving a control command from a user, a display unit 119 outputting information of a control command selectable by the user, and a main control unit (not shown) controlling a command for performing an operation of the laundry dryer 1.

[0150] On the other hand, the input unit 118 can be configured to include a power supply request unit requesting power supply to the laundry dryer, a progress input unit allowing the user to select a desired progress among a plurality of progress, an execution request unit requesting start of the progress selected by the user, and the like.

[0151] The display unit 119 can be configured to include at least one of a display panel capable of outputting characters and / or numbers, and a speaker capable of outputting a voice signal and a sound. The user can easily grasp a current management state, a remaining time, and the like situation through the information output by the display unit 119.

[0152] Inside the cabinet 10 is provided with the drum 20 rotatably provided and providing a space for accommodating clothes (an article to be dried), a duct portion 30 supplying air to the drum 20 and discharging air inside the drum 20, and an electric field generator 40 forming an electric field inside the drum 20.

[0153] The drum 20 can include a cylindrical drum body 21 having an open front surface, a first support portion 22 rotatably supporting the front surface of the drum body 21 inside the cabinet 10, and a second support portion 23 rotatably supporting a rear surface of the drum body 21.

[0154] An inner space of the drum 20 serves as a drying chamber in which drying is performed. On the other hand, the drum 20 of the present application can serve as a negative electrode of a capacitor.

[0155] The first support portion 22 can be provided to include a first fixing body 22a fixed to the inside of the cabinet 10, and a drum inlet 22b provided to penetrate the first fixing body 22a to communicate the inlet 111 and the inside of the drum body 21.

[0156] The first fixing body 22a can be provided with an air outlet 22c communicating with the duct portion 30.

[0157] As shown in Figure 2 the air outlet 22c is a passage allowing the internal air of the drum body 21 to move to the duct portion 30, and can be provided as a through-hole provided through the first fixing body 22a.

[0158] The second support portion 23 is provided to include a second fixing body 23a fixed to the inside of the cabinet 10.

[0159] An air inlet 23b is formed in the second support portion 23, which is provided through the second fixing body 23a and communicates the inside of the drum body 21 with the inside of the cabinet 10.

[0160] The outer circumferential surface of the drum body 21 can include one or more notched portions 24 recessed in the circumferential direction. In this case, the positive electrodes 41 to be described below can be spaced apart from each other at a predetermined interval in the notched portions 24.

[0161] The detailed structure of the drum 20 will be described below.

[0162] The cylindrical drum body 21 can be rotated by means of various types of driving units 50.

[0163] For example, Figure 2 one embodiment is shown in which the driving unit 50 includes a drum motor 51 fixed inside the cabinet 10, a pulley 52 rotated by the drum motor 51, and a belt 53 connecting the circumferential surface of the pulley 52 and the circumferential surface of the drum body 21.

[0164] In this case, the side panel 13 can be provided with a roller R for rotatably supporting the circumferential surface of the drum body 21.

[0165] However, the present application is not limited thereto, and a direct driving type driving unit in which the drum motor 51 is directly connected to the drum to rotate the drum without passing through the pulley and the belt is also applicable, which also falls within the scope of the present application. For convenience, the following description will be based on the illustrated embodiment of the driving unit 50.

[0166] The duct portion 30 includes an exhaust duct 31 connected to the air outlet 22c, and a supply duct 32 connected to the air inlet 23b.

[0167] The exhaust duct 31 can serve as a passage for exhausting the air inside the drum body 21 to the outside of the cabinet 10. Accordingly, the water vapor generated from the articles to be dried can be exhausted to the outside of the cabinet 10 by the flow force of the circulation fan 33.

[0168] The exhaust duct 31 includes a suction duct 31a, a fan housing 31b, and an exhaust duct 31c.

[0169] The suction duct 31a is formed to communicate with the air outlet 22c, and can be a passage to guide air inside the drum 20 to the outside. Specifically, the suction duct 31a can provide a flow path formed downward from the air outlet 22c in the direction of gravity. For example, the suction duct 31a can be a tube having a flat shape in the front-rear direction. In this case, a lower surface of the suction duct 31a can be inclined at a predetermined angle with respect to the ground. In this configuration, water that has condensed on the inner surface of the suction duct 31a after passing through the air outlet 22c can flow downward by its own weight and be collected, and be discharged to the outside of the laundry dryer 1 by the flow force of the circulating fan 33, which will be described below. Thus, it is possible to prevent moisture from accumulating inside the suction duct 31a, thereby preventing the breeding of bacteria and the like.

[0170] The fan housing 31b is formed to communicate with the suction duct 31a, and is formed in a cylindrical shape to accommodate an impeller 33a of the circulating fan 33, which will be described below. Thereby, air passing through the suction duct 31a can flow by rotation of the impeller 33a, and be discharged to the outside of the laundry dryer 1.

[0171] One side of the exhaust duct 31c can be formed to communicate with the fan housing 31b, and the other side can be disposed outside the laundry dryer 1 through the rear panel 12. With this configuration, air discharged from the fan housing 31b can be discharged to the outside of the laundry dryer 1 through the exhaust duct 31c.

[0172] Further, the duct portion 30 can include the circulating fan 33 to move air along the exhaust duct 31. The circulating fan 33 is disposed to include the impeller 33a disposed in the exhaust duct 31, and an impeller motor 33b to rotate the impeller 33a and provide a flow force to air moving along the exhaust duct 31. For example, the impeller 33a can be accommodated in the fan housing 31b of the exhaust duct 31c to provide a flow force to air.

[0173] The supply duct 32 can be a passage to guide air outside the drum body 21 into the drum body 21. The supply duct 32 can communicate with the air inlet 23b to communicate the inside of the cabinet 10 with the drum body 21. With this configuration, when the circulating fan 33 is driven to generate a negative pressure inside the drum body 21, air outside the drum body 21 passes through the supply duct 32, passes through the air inlet 23b, and can be introduced into the inside of the drum body 21.

[0174] Meanwhile, the air flowing inside the drum 20 can be indoor air, heated air, or a combination of both.

[0175] The electric field generator 40 can be various devices capable of generating an electric field inside the drum 20. For example, the electric field generator 40 can be a device that uses an electric field generated between a positive electrode and a negative electrode to vibrate water molecules to perform heating (dielectric heating) and evaporation.

[0176] Specifically, the electric field generator 40 can include a positive electrode 41 that forms an electric field with respect to the drum 20 as a negative electrode.

[0177] A specific shape of the positive electrode 41 will be described below.

[0178] The electric field generator 40 can include a matcher 42 connected to the positive electrode 41 to supply a predetermined frequency of current to the positive electrode 41. The matcher 42 can be supported by being coupled to the lower panel 15.

[0179] The matcher 42 can be electrically connected to the positive electrode 41 to adjust an inductance or a capacitance so as to be tuned to a predetermined frequency. In addition, the matcher 42 can match an impedance of a high frequency power source to an impedance of a load side. The matcher 42 can include a variable inductance and a variable capacitance. As for a detailed configuration of the matcher 42, any means known in the art can be employed, and thus a description of the detailed configuration will be omitted.

[0180] Meanwhile, the matcher 42 can include a heat sink (not shown) and a cooling fan. With this configuration, air inside the cabinet 10 can recover heat when passing through the heat sink, and the cooling fan can cause the heated air to be introduced into the cabinet 10, and the heated air can be introduced into the drum 20 again to support drying of the articles to be dried.

[0181] The electric field generator 40 can include a power supply unit 43 electrically connected to the matcher 42 to perform power supply.

[0182] The power supply unit 43 is electrically connected to the matcher 42 to supply a constant frequency current to the positive electrode 41. Thereby, when power is applied to the positive electrode 41, an electric field can be generated in the drum 20.

[0183] In the present embodiment, the power supply unit (power supply unit) 43 can refer to an RF power device (RF power source). The drum 20 is connected to the power supply unit 43 of a fixed frequency together with the control unit 100 through the matcher 42 to measure appropriate power, drying, load size, and time setting of the end of drying, and perform a drying process. In this case, a preferred operation frequency of the power source 21 is in the range of 1 MHz to 50 MHz.

[0184] RF power can be applied by the power supply unit 43 when the articles to be dried are tumbled and / or stopped.

[0185] A drying process of the object to be dried will be described hereinafter.

[0186] In addition, the laundry dryer 1 according to the present application can further include a filter unit F, which is a device for removing foreign substances such as lint and dust generated during the drying process of laundry such as clothes.

[0187] As for the detailed configuration of the filter unit F, any device known in the art can be employed, and the detailed description thereof will be omitted.

[0188] The electric field generator 40 can be directly controlled by the control unit 100.

[0189] The control unit 100 is configured to control the operation of the laundry dryer 1 according to a user input applied through the input unit 118. The control unit 100 can be constituted by a printed circuit board and elements mounted on the printed circuit board. When a user inputs a control command, such as selection of a clothes treatment course or operation of the laundry dryer 1, through the input unit 118, the control unit 100 can control the operation of the laundry dryer 1 according to a preset algorithm.

[0190] The specific control contents of the control unit 100 in the present application will be described hereinafter.

[0191] Figure 9 is a front view of a notch portion in a laundry dryer according to an embodiment of the present application in a partially disassembled state, Figure 10 is a front view for explaining an electric field generator in a laundry dryer according to an embodiment of the present application, Figure 11 is a perspective view for explaining an electric field generator in a laundry dryer according to an embodiment of the present application.

[0192] The configuration of the positive electrode 41 and the drum 20 in the laundry dryer 1 according to an embodiment of the present application will be described with reference to Figure 4 , Figure 5 and Figures 9 to 11 .

[0193] The drum 20 can include a drum body 21, a first support portion 22, a second support portion 23, a notch portion 24, a lifter 25, and a ground electrode 26. Meanwhile, detailed descriptions of the first support portion 22 and the second support portion 23 will be omitted in order to avoid repetition of the above-described descriptions.

[0194] The drum body 21 is formed in a hollow shape so that the object to be dried can be accommodated in an internal space. In other words, the drum body 21 can be formed in a cylindrical or ring shape.

[0195] The notch portion 24 is formed in a ring shape and is connected to the drum body 21 to rotate integrally.

[0196] In this case, the drum body 21 is manufactured in a plurality, and can be coupled to the recessed portion 24, or can be integrally formed with the recessed portion 24.

[0197] Specifically, the recessed portion 24 can be formed by indenting a portion of the outer circumferential surface of the cylindrical drum body 21 inward in the radial direction.

[0198] Specifically, the recessed portion 24 can include a connection portion 24a formed in a ring shape and connected to the drum body 21, and a positive electrode receiving portion 24b bent inward in the radial direction at the connection portion 24a and forming a space for accommodating the positive electrode 41.

[0199] Thereby, a portion of the drum 20 in which the recessed portion 24 is formed can have a reduced diameter. In other words, when viewed from the outside of the drum 20, the recessed portion 24 can be in the form of a groove recessed inward in the circumferential direction on the outer circumferential surface of the drum body 21.

[0200] The drum body 21 can be alternately disposed with the recessed portion 24. For example, three drum bodies 21 can be disposed, two recessed portions 24 can be disposed, and one recessed portion 24 can be disposed between two drum bodies 21. In other words, two recessed portions 24 can be disposed at a predetermined distance from each other. However, the number of recessed portions 24 and the number of drum bodies 21 are not limited thereto, and can vary depending on the overall size of the drum 20.

[0201] On the other hand, the recessed portion 24 can be provided with an air inlet 24c to communicate the inside of the drum body 21 with the inside of the cabinet 10. Thereby, air outside the drum 20 can be introduced into the drum 20 through the air inlet 24c.

[0202] Specifically, when the circulation fan 33 is driven and air inside the drum 20 is suctioned into the exhaust duct 31, a negative pressure can be generated inside the drum 20, and air outside the drum 20 can be forcibly introduced into the hollow (portion) of the drum 20 through the air inlet 24c of the recessed portion 24.

[0203] Such air flow can quickly remove water vapor evaporated from the articles to be dried. In addition, the air flow causes moisture inside the articles to be dried to evaporate to additionally remove moisture from the articles to be dried. In addition, when power is applied to the positive electrode 41 and the matcher 42 to generate heat, it can be cooled to extend the lifespan.

[0204] Meanwhile, at least one lifter 25 can be provided at the inner circumferential surface of the drum 20. For example, three lifters 25 can be provided at fixed intervals (120 degrees). The lifter 25 can be fixedly coupled to the inner circumferential surface of the drum body 21 and the inner surface of the notch portion 24, and can be formed in a shape protruding from the inner circumferential surface of the drum body 21 and the inner surface of the notch portion 24 toward the rotation axis of the drum 20. The lifter 25 can be provided to be in contact with the articles to be dried accommodated in the drum 20. With this configuration, when the drum 20 rotates, the articles to be dried can be rotated together with the drum 20 to a predetermined angle while being supported by the lifter 25, and then fall to the lower side by their own weight. In this process, the articles to be dried can be naturally mixed. In other words, the articles to be dried can be agitated by the lifter 25, tumbling motion of the articles to be dried can be enhanced, and the articles to be dried can be uniformly heated while being shaken around the rotation axis of the drum 20.

[0205] Accordingly, it has an effect in that bunching by the lifter 25 on the articles to be dried can be inhibited.

[0206] On the other hand, the rotating conductive drum 20 is connected to the ground electrode 26 by direct rotation or capacitive coupling connection. For example, the ground electrode 25 can be selectively activated or continuously connected only when RF power is applied.

[0207] The connection between the ground electrode and the drum body 21 can be continuously activated during the motion. Alternatively, the connection between the ground electrode and the drum body 21 can be selectively connected at the time of rotation or stop.

[0208] The positive electrode 41 can include a positive electrode plate 41a, an air passage hole 41b, a support frame 41c, a coupling frame 41d, and a fixing panel 41e.

[0209] The positive electrode plate 41a can have an arc shape cut from a ring shape at a predetermined angle and a ring plate. For example, the positive electrode plate 41a can be disposed on a concentric circle with respect to the center axis of the drum body 21, and can be an arc plate formed in a range of 120 degrees with the rotation axis of the drum body 20 as the origin. In other words, the positive electrode 41 can have a ring shape cut into one-third.

[0210] Meanwhile, in the present embodiment, the positive electrode plate 41a is configured in a pair and disposed to face each other, but is not limited thereto.

[0211] In addition, both ends of the positive electrode plate 41a can be formed to extend outward in a radial direction to be fixedly coupled to the coupling frame 41d to be described below.

[0212] Multiple air passage holes 41b can be formed in the positive electrode plate 41a, and these air passage holes can be formed to correspond to the positions of the air inlets 24a in the recess 24. With this configuration, air from outside the roller 20 can flow into the roller 20.

[0213] Specifically, when the circulating fan 33 is driven and the air inside the drum 20 is drawn into the exhaust pipe 31, a negative pressure can be generated inside the drum 20, and the air outside the drum 20 can be forcibly introduced into the hollow (partial) part of the drum 20 through the air passage hole 41b.

[0214] Furthermore, it has the effect of cooling the overheated positive electrode plate 41a when air passes through the air channel hole 41b through the positive electrode plate 41a.

[0215] The support frame 41c can be formed to extend downward from the positive electrode plate 41a in the direction of gravity. The support frame 41c can contact the upper outer peripheral surface of the exhaust pipe 31c provided on the lower side, and the positive electrode plate 41a can be supported by the support frame 41c.

[0216] The connecting frame 41d can be configured to connect a pair of positive electrode plates 41a to each other. Specifically, the connecting frame 41d is formed as a flat strip with one end bent, and the pair of positive electrode plates 41a are respectively fixedly connected to two planes at the bent end. In this case, the bending angle of the connecting frame 41d is formed to correspond to the shape of the two ends of the positive electrode plates 41a.

[0217] Two connecting frames 41d can be provided to correspond to the positions of the two ends of the positive electrode plate 41a. With this configuration, both ends of the positive electrode plate 41a can be fixed to the connecting frames 41d.

[0218] The fixing panel 41e can be formed in the shape of a flat plate, and its two ends in the longitudinal direction can be respectively connected to the connecting frame 41d. Thus, the fixing panel 41e is used to fix the positive electrode plate 41a to maintain a constant distance. In other words, multiple positive electrode plates 41a can be maintained at a predetermined distance by the fixing panel 41e, and can maintain a predetermined distance from the roller 20 even when the roller 20 is rotating.

[0219] The positive electrode 41 can be disposed below the roller 20 and can be spaced apart from the roller body 21 and the notch 24 at a predetermined distance.

[0220] The positive electrode 41 can be positioned to correspond to the position of the recess 24 formed on the outer peripheral surface of the roller body 21.

[0221] With this configuration, when the articles to be dried are placed inside the drum 20, the positive electrode 41 can apply a sufficient electric field to the articles to be dried even if they are gathered in the lower portion of the drum body.

[0222] In addition, the positive electrode 41 can be disposed in the space of the notch portion 24 formed inwardly recessed based on the outer circumferential surface of the drum body 21. For example, the positive electrode 41 can be disposed corresponding to two notch portions 24 between which a predetermined interval is formed. In this case, the two positive electrodes 41 can be fixed to the pair of fixing panels 41e so as to maintain the distance therebetween.

[0223] With this arrangement, the positive electrode 41 and the outer circumferential surface of the drum body 21 as a negative electrode can be alternately disposed in the axial direction.

[0224] Meanwhile, the width and circumference of the positive electrode 41 and the ratio thereof can be varied.

[0225] The positive electrode 41 can be made of bare metal or insulated metal. An insulator can be coated on the positive electrode 41. Conversely, the drum 20 can be made of a conductive material (i.e., metal) or an insulating material coated with a conductive layer.

[0226] Meanwhile, the notch portion 24 of the drum 20 is spaced apart from the positive electrode 41. Accordingly, the positive electrode 41 is fixed in space, whereas the drum 20 can rotate. The drum 20 can freely rotate clockwise and counterclockwise about the rotation axis. In addition, since the drum 20 does not come into contact with the positive electrode 41, the rotational speed can be freely varied.

[0227] In other words, the positive electrode 41 and the drum 20 can be disposed to be relatively rotatable. In this case, the articles to be dried (clothes) can be disposed between the fixed positive electrode 41 and the rotating conductive drum 20.

[0228] For example, the positive electrode 41 can be disposed in the space formed in the notch portion 24 and can be disposed in a radial direction perpendicular to the outer circumferential surface of the drum body 21. Thereby, the articles to be dried can be located in the space disposed perpendicular to each other by the positive electrode 41 and the outer circumferential surface of the drum body 21.

[0229] With this configuration, when RF power is applied through the power supply unit 43, the electric field between the positive electrode 41 and the drum 20 electrically penetrates the notch portion 24, the electric field can be formed in the inner space of the drum 20, and the moisture contained in the articles to be dried can be heated and evaporated while being vibrated by the electric field.

[0230] More specifically, the positive electrode 41 can generate an RF (Radio Frequency) capacitive coupling effect by maintaining an electric field required for drying the articles to be dried in relation to the drum 20. In other words, a relatively low RF frequency is preferably used to minimize a parasitic capacitance generated in the drum 20 as a negative electrode. For example, a frequency of 10 MHz or more and 15 MHz or less can be used for the positive electrode 41. In this case, in order to improve energy efficiency, the articles to be dried are preferably close to the drum 20 and the positive electrode 41. Meanwhile, the parasitic capacitance is independent of a capacitance of the articles to be dried themselves, and can be defined as an arbitrary capacitance between the positive electrode 41 and the drum 20.

[0231] An AC current can be generated on a capacitive circuit by a semi-conductive (wet) load of the articles to be dried, and a single-frequency RF generation current is applied between at least one fixed positive electrode 41 and the rotating drum 20, so that dielectric heating can be performed on the articles to be dried.

[0232] Figure 12 is a block diagram for explaining a control configuration in a laundry dryer according to an embodiment of the present application.

[0233] Referring to Figures 1 to 3 and Figure 12 , a configuration for control in the present application will be described as follows.

[0234] First, the control unit 100 can be in signal or electrical connection with the input unit 118 and the display unit 119. Thereby, when a user inputs a control command to the input unit 118, the input unit 118 can transmit information about the control command to the control unit 100, and the control unit 100 can store the information. Further, the control unit 100 can transmit information about the user-input control command to the display unit 119 to display the information to the user. Further, the control unit 100 can transmit information such as a load of the articles to be dried, a drying progress state, and a time required for drying, etc. to the display unit so that the display unit 119 can inform the user.

[0235] Further, the control unit 100 is connected to the sensor unit 101 and the door switch unit 102. The sensor unit 101 can measure a temperature of the articles to be dried, an air flow amount inside the drum 20, etc. The door switch unit 102 can inform the control unit 100 whether the door 112 is opened or closed with respect to the drum 20, and can inform the control unit 100 whether the door 112 is locked or released when the door 112 is closed. Further, the control unit 100 can transmit a control signal to the door switch unit 102 to selectively open and close the door 112, and can transmit a control signal to selectively lock and release the door when the door is closed.

[0236] Further, the control unit 100 can be connected to the drum motor 51. Thereby, the control unit 100 can drive the drum motor 51 to rotate or stop the drum 20, control the rotational speed of the drum 20, and switch the rotational direction of the drum 20.

[0237] Further, the rotational speed of the drum 20 can be tracked by the control unit 100. This is to determine the optimal power adjustment in the drying cycle, since water is gradually evaporated from the articles to be dried.

[0238] Further, the control unit 100 can be connected to the impeller motor 33b. Thereby, the control unit 100 can rotate or stop the circulation fan 33 by driving the impeller motor 33b, and can control the rotational speed of the circulation fan 33. Accordingly, the control unit 100 can control the air discharge amount in the drum 20.

[0239] Further, the control unit 100 can control the electric field generator 40. In other words, the control unit 100 can control the power supply unit 43 to apply power to the positive electrode 41, and can cut off the power application. In addition, the control unit 100 can control the matcher 42 to match the source impedance with the impedance on the load side. With this configuration, the control unit 100 can apply a stable electric field to the articles to be dried to perform dielectric heating on the articles to be dried.

[0240] Specifically, the control unit 100 can control at least one of the RF power, the impedance Z, the RF reflection coefficient, the VSWR, etc. to be changed in real time, so as to transmit optimal energy to the articles to be dried. The control unit 100 uses these measured values to determine the type, size, and wetting of the load, and the optimal time to end the drying process.

[0241] Meanwhile, the control unit 100 can transmit a notification signal or a message to the user before the drying starts and at the end of the drying process. The notification signal can be notified in a visual manner through the display unit 119, or in an audible manner through a speaker (not shown), as described above. The message can also be sent to the user's mobile phone in the form of a text message, for example, using the SMS protocol.

[0242] Figure 13 FIG. 1 is a flowchart showing a program of a control method of a laundry dryer according to an embodiment of the present application, Figure 16 FIG. 2 is a flowchart for explaining a procedure of controlling the rotational speed of a drum and RF power for impedance matching in a control method of a laundry dryer according to an embodiment of the present application in a drying process.

[0243] A method of controlling a laundry dryer according to an embodiment of the present application will be described with reference to Figures 1 to 3 and Figures 9 to 16 A method of controlling a laundry dryer according to an embodiment of the present application will be described with reference to

[0244] The control method of the laundry dryer of the present application can include a drying preparation step (S10), a load sensing step (S20), a drying step (S30), an agitation step (S40), and a cooling step (S60).

[0245] In the drying preparation step (S10), the articles to be dried are accommodated in the drum 20, and a drying course can be set by a user's control input. When the articles to be dried are put into the drum 20, they are placed at the bottom of the drum 20 under the action of gravity, and the articles to be dried are in contact with the notch portion 24 provided near the positive electrode 41 and the drum main body 21 having electrical conductivity.

[0246] In the drying preparation step (S10), the user can input information on the material and the number of the articles to be dried through the input unit 118, and the input unit 118 can transmit the information to the control unit 100.

[0247] In this case, information on the evaporation heat of each material of the articles to be dried can be pre-stored in the control unit 100. Thereby, the control unit 100 can set the magnitude of the energy applied to the articles to be dried according to the material and the size of the articles to be dried.

[0248] In the load sensing step (S20), the washing amount can be determined by sensing the load of the articles to be dried.

[0249] The washing amount can be determined by measuring the current value of the drum motor 51 and sensing the load acting on the drum motor 51 while the drum 20 is rotating.

[0250] For example, when the drum 20 is controlled to rotate at a speed at which a predetermined washing amount is sensed, as the washing amount increases, a greater current must be applied to the drum motor 51. Thereby, the control unit 100 can control the current value applied to the drum motor 51. Thereby, the control unit 100 can calculate the washing amount according to the sensed current value of the drum motor 51.

[0251] On the other hand, in the load sensing step (S20), the drum 20 can be rotated at a predetermined agitation rotational speed w m The agitation rotational speed w m will be described in detail in the agitation step (S40).

[0252] Meanwhile, the control unit 100 can pre-store a moisture content according to a material of the articles to be dried. Thereby, the control unit 100 can predict an evaporation time of moisture contained in the articles to be dried according to an amount of energy applied to the articles to be dried, based on information about a material and an amount of the articles to be dried collected through the drying preparation step (S10) or the load sensing step (S20). Further, the control unit 100 can transmit the predicted moisture evaporation time to the display unit 119, and the display unit 119 can display the predicted time to the user.

[0253] In the drying step (S30), the control unit 100 can apply power to the positive electrode 41 and rotate the drum 20 to evaporate moisture contained in the articles to be dried by dielectric heating.

[0254] Specifically, the control unit 100 can apply power to the positive electrode 41 to generate an electric field with respect to the drum 20 as a negative electrode. In this state, RF power can be applied to the drum 20 and the articles to be dried. In this case, a current applied to the positive electrode 41 can be maintained at a predetermined frequency by the matcher 42, and a source impedance of the high-frequency power source and an impedance of a load side can be continuously matched by the matcher 42.

[0255] The control unit 100 can control the matcher 42 and the power supply unit 43 to measure appropriate power, a drying, a load size, and a drying end time, and perform a drying process. In this case, a preferred operation frequency of the power source 21 is in a range of 1 MHz to 50 MHz.

[0256] Through this configuration, the positive electrode 41 maintains an electric field required for drying the articles to be dried with respect to the drum 20 to generate a radio frequency (RF) capacitive coupling effect. In this case, it is preferable to use a relatively low RF frequency to minimize a parasitic capacitance generated in the drum 20 as a negative electrode. For example, for the positive electrode 41, a frequency of 10 MHz or more and 15 MHz or less can be used.

[0257] Accordingly, it is possible to generate an alternating current through a semi-conductive (wet) load of the articles to be dried in a capacitive circuit, and the articles to be dried can be dielectrically heated by generating a current through application of an RF of a single frequency between at least one positive electrode 41 and the drum 20.

[0258] In the drying step (S30), the control unit 100 can apply RF power to the positive electrode 41 for a preset drying time td. For example, the control unit 100 can apply RF power to the positive electrode 41 for a period of time of 80 seconds or more and 100 seconds or less, and preferably, for a period of time of 90 seconds.

[0259] On the other hand, in a conventional dielectric heating type dryer, when power is applied to the positive electrode, the drum stops without rotating. This enables the matcher to continuously heat after impedance matching at the start of drying, and thus, it can efficiently heat the moisture contained in the article to be dried at high speed.

[0260] However, when the internal temperature of the article to be dried rapidly increases as described above, there is a problem that local overheating occurs inside the article to be dried.

[0261] In particular, when the article to be dried is a dyed synthetic fiber, there is a problem that color transfer occurs due to local overheating. In the case of a synthetic fiber, if the temperature exceeds 50 degrees Celsius, color transfer can occur.

[0262] To solve this problem, the conventional dryer rotates the drum for 5 seconds to mix the article to be dried after 90 seconds of drying. However, since dielectric heating is performed again in a state in which heat inside the article to be dried is not sufficiently discharged, there is a problem that the internal temperature of the article to be dried continuously increases as the drying cycle proceeds.

[0263] Reference Figure 14 With consideration of the temperature change of the article to be dried, it can be seen that the temperature change inside the article to be dried when the article to be dried is dried using the conventional dielectric heating method. The process of applying RF power for 90 seconds while the drum is stopped, stopping the application of RF power for 5 seconds, and then rotating the drum is repeated for 36 cycles, and as a result, it can be seen that the internal temperature of the article to be dried increases to 145 degrees Celsius.

[0264] In addition, in the case in which heating is performed again after internal heat is sufficiently discharged, the energy and time required to perform dielectric heating again are large, and thus, there is a problem that the drying efficiency decreases.

[0265] Therefore, it is necessary to control so that local overheating does not occur while maintaining heating of the article to be dried.

[0266] To solve this problem, in the drying step (S30) of the present invention, the control unit 100 rotates the drum 20 while applying power to the positive electrode 41. In other words, in the drying step (S30), the control unit 100 rotates the drum 20 at a predetermined drying rotational speed wd.

[0267] In this case, the rotational speed of the drum 20 can be slower than the rotational speed of the drum 20 in the load sensing step (S20) or the rotational speed of the drum 20 in the agitation step (S40) described below.

[0268] Specifically, the rotational speed range of the drum 20 in the drying step (S30) can be determined from two aspects.

[0269] First, the rotational speed of the drum 20 in which local overheating does not occur in the drying step (S30) is derived in the following manner.

[0270] In order to prevent color transfer to the articles to be dried, the temperature of the articles to be dried should be maintained at 50 degrees Celsius or less. To this end, it is necessary to maintain a low temperature rise per heating time. The temperature rise per unit time is as follows.

[0271] [Equation 1]

[0272]

[0273] In this case, ΔT denotes the amount of temperature rise (°C), and Δt denotes the heating time (sec). In addition, Cp is the specific heat of the dielectric (J / kg·K), f is the frequency (Hz), and ρ is the density of the dielectric (kg / m 3 ).

[0274] Meanwhile, Pv is the power absorbed per unit volume of the dielectric, and it can be expressed as the following equation.

[0275] [Equation 2]

[0276] P v = 2π·f·ε0·ε"E 2

[0277] In this case, ε" refers to the relative electric loss coefficient, and E refers to the electronic density.

[0278] Here, when considering the moving distance generated according to the rotation of the drum 20, the above Equations 1 and 2 are combined to obtain the following equation.

[0279] [Equation 3]

[0280]

[0281] When the outside temperature is 20 degrees Celsius, the temperature change must be 30 degrees or less in order to maintain the temperature of the articles to be dried at 50 degrees Celsius or less. From this, the minimum rotational speed of the drum 20 in the drying step (S30) is determined by the following equation.

[0282] [Equation 4]

[0283]

[0284] In this case, θ (rad) denotes an angle at which the positive electrode 41 is located with respect to the rotational axis of the drum 20, and α denotes the rotational speed of the drum 20. Thus, in the present application, the rotational speed of the drum 20 is proportional to the angle at which the positive electrode 41 is located with respect to the rotational axis of the drum 20.

[0285] For example, if 4000 W of RF power at a frequency of 13.56 MHz is applied to the positive electrode, and the arc-shaped positive electrode 41 is rotated around the drum 20 at an angle (range) of 120 degrees (2π / 3), the minimum rotational speed in the drying step (S30) of the present application is 1.6 rpm. Further, considering that the minimum rotational speed α of the drum 20 is proportional to θ (rad), the proportional relationship between the angle at which the positive electrode 41 is rotated around the drum 20 and the minimum rotational speed of the drum 20 is as follows.

[0286] [Equation 5]

[0287]

[0288] In other words, the minimum rotational speed of the drum 20 is 12 / 5π times the angle at which the positive electrode 41 is rotated around the drum 20, with the rotational axis of the drum 20 as the origin.

[0289] Meanwhile, in the drying step (S30), the control unit 100 can rotate the drum 20 while maintaining the rotational speed of the drum 20 at 7 rpm or less.

[0290] Specifically, in the dielectric heating type RF dryer, as the rotational speed of the drum 20 increases, the load increases, and thus it is difficult for the matcher 42 to match the source impedance with the load-side impedance. Thus, when the rotational speed of the drum 20 exceeds 7 rpm, dielectric heating can not be performed on the inside of the article to be dried.

[0291] Therefore, in the drying step (S30), the control unit 100 can rotate the drum 20 at an angle of 12 / 5π times or more the angle at which the positive electrode 41 is rotated around the drum 20, and the rotational speed is 7 rpm or less.

[0292] With this configuration, the control method of the laundry dryer according to the embodiment of the present application has the effect of preventing the occurrence of color transfer by maintaining the temperature of the article to be dried at 50 degrees Celsius or less while removing moisture from the article to be dried by dielectric heating of the inside of the article to be dried.

[0293] Further, in this method, the matcher 42 takes about 7 seconds to match the impedance in order to supply RF power again. Thus, there is a problem in that power can be wasted during this process, and the entire drying time increases.

[0294] To solve this problem, in the drying step (S30) of the present application, the control unit 100 rotates the drum 20 while applying power to the positive electrode 41. In this case, the rotation speed of the drum 20 can be slower than the rotation speed of the drum 20 in the load sensing step (S20), or the rotation speed of the drum 20 in the agitation step (S40) described below.

[0295] Further, in the drying step (S30) of the present application, when the reflectance of the electric field exceeds a predetermined ratio, the control unit 100 reduces the rotation speed of the drum, and when the reflectance of the electric field is less than or equal to the predetermined ratio, the control unit can increase the power applied to the positive electrode.

[0296] Specifically, the drying step (S30) includes a drying entry step (S31), a first power increase step (S33), a second power increase step (S35), a third power increase step (S37), and a rotation maintenance step (S39).

[0297] In the drying entry step (S31), the control unit 100 can apply a preset startup power Pi to the positive electrode 41, and rotate the drum 20 at a preset startup rotation speed Wi. In other words, when power starts to be applied to the positive electrode 41 according to the control command of the control unit 100, the power supply unit 43 can apply power corresponding to the preset startup power Pi to the positive electrode 41.

[0298] For example, in the drying entry step (S31), the control unit 100 can apply power of 100 W or more and 200 W or less to the positive electrode 41 through the power supply unit 43, and rotate the drum 20 at a rotation speed of 5 rpm or more and 10 rpm or less.

[0299] After the drying entry step (S31), the control unit 100 can obtain the reflectance through the matcher 42. In other words, the matcher 42 can measure the electric field reflected wave reflected from the drying object and returned, which the control unit 100 compares with the electric field incident wave generated at the positive electrode 41 to obtain the reflectance of the electric field (S32).

[0300] In this case, when the reflectance of the electric field exceeds a predetermined ratio, the control unit 100 can reduce the rotation speed of the drum 20. For example, when the reflectance of the electric field exceeds 5%, the rotation speed of the drum 20 can be reduced by 10% (S32a). In other words, the rotation speed W of the drum 20 can be 90% of the startup rotation speed (W = 0.9 x Wi).

[0301] Then, the control unit 100 can repeat the process of reducing the rotation speed of the drum 20 until the reflectance of the electric field of the drum 20 is less than or equal to a predetermined ratio. If the rotation speed is reduced n times, the rotation speed W of the drum 20 can be (0.9) n× Wi (W = (0.9) n × Wi).

[0302] Meanwhile, when the reflectance of the electric field is less than or equal to a predetermined ratio, the control unit 100 can perform a first power increase step (S33). For example, when the reflectance of the electric field is 5% or less, the first power increase step (S33) can be performed.

[0303] In the first power increase step (S33), the control unit 100 can increase the power P applied to the positive electrode 41. For example, when the reflectance of the electric field is 5% or less, the control unit 100 can deliver RF power equivalent to 20% of the preset drying power Pd to the positive electrode 41 through the power supply unit 43 (P = 0.2 x Pd).

[0304] Meanwhile, the rotational speed W1 of the drum 20 in the first power increase step (S33) can maintain the rotational speed W of the drum 20 in the previous step. In other words, if the rotational speed of the drum 20 is decreased after the drying entry step (S31), the decreased rotational speed of the drum 20 is maintained (W1 = (0.9) n × Wi), if the rotational speed of the drum 20 is not decreased after the drying entry step (S31), the starting rotational speed can be maintained (W1 = Wi).

[0305] When the reflectance of the electric field is less than or equal to a predetermined ratio, power equivalent to 20% of the preset drying power can be applied to the positive electrode.

[0306] After the first power increase step (S33), the control unit 100 can obtain the reflectance through the matcher 42. In other words, the matcher 42 can measure the electric field reflection wave reflected from the article to be dried and returned, and the control unit 100 compares it with the electric field incidence wave generated from the positive electrode 41 to obtain the reflectance of the electric field (S34).

[0307] In this case, when the reflectance of the electric field exceeds a predetermined ratio, the control unit 100 can decrease the rotational speed W of the drum 20. For example, when the reflectance of the electric field exceeds 5%, the rotational speed of the drum 20 can be decreased by 10% (S34a). In other words, the rotational speed W of the drum 20 can be 90% of the starting rotational speed (W = 0.9 x W1).

[0308] Then, the control unit 100 can repeat the process of decreasing the rotational speed of the drum 20 until the reflectance of the electric field of the drum 20 is less than or equal to a predetermined ratio. If the rotational speed is decreased n times, the rotational speed W of the drum 20 can be (0.9) n × W1 (W = (0.9) n × W1).

[0309] Meanwhile, when the reflectance of the electric field is less than or equal to a predetermined ratio, the control unit 100 can perform a second power increase step (S35). For example, when the reflectance of the electric field is 5% or less, the second power increase step (S35) can be performed.

[0310] In the second power increase step (S35), the control unit 100 can increase the power P applied to the positive electrode 41. In other words, when the power applied to the positive electrode 41 corresponds to 20% of the drying power Pd, and the reflectance of the electric field is less than or equal to a predetermined ratio, the power supply unit 43 can apply power corresponding to 50% of the drying power Pd to the positive electrode 41 according to a control command of the control unit 100.

[0311] For example, when the reflectance of the electric field is 5% or less, the control unit 100 can apply radio frequency power corresponding to 50% of the preset drying power Pd (P = 0.5 × Pd) to the positive electrode 41 through the power supply unit 43.

[0312] Meanwhile, in the second power increase step (S35), the rotational speed W2 of the drum 20 can maintain the rotational speed W of the drum 20 in the previous step. In other words, if the rotational speed of the drum 20 is decreased, the decreased rotational speed of the drum 20 (W2 = (0.9) n × W1) is maintained, and if there is no rotational speed decrease after the drying entry step (S31), the starting rotational speed Wi (W2 = Wi) can be maintained.

[0313] After the second power increase step (S35), the control unit 100 can obtain the reflectance of the electric field through the matching unit 42. In other words, the matching unit 42 can measure the electric field reflected wave reflected from the articles to be dried and returned, and the control unit 100 compares it with the electric field incident wave generated from the positive electrode 41 to obtain the reflectance of the electric field (S36).

[0314] In this case, when the reflectance of the electric field exceeds a predetermined ratio, the control unit 100 can decrease the rotational speed W of the drum 20. For example, when the reflectance of the electric field exceeds 5%, the rotational speed of the drum 20 can be decreased by 10% (S36a). In other words, the rotational speed W of the drum 20 can be 90% of the starting rotational speed (W = 0.9 × W2).

[0315] Then, the control unit 100 can repeat the process of decreasing the rotational speed of the drum 20 until the reflectance of the electric field of the drum 20 is less than or equal to a predetermined ratio. If the rotational speed is decreased n times, the rotational speed W of the drum 20 can be (0.9) n × W2 (W = (0.9) n × W2).

[0316] Meanwhile, when the reflectance of the electric field is less than or equal to a predetermined ratio, the control unit 100 can perform a third power increase step (S37). For example, when the reflectance of the electric field is 5% or less, the third power increase step (S37) can be performed.

[0317] In the third power increase step (S37), the control unit 100 can increase the power P applied to the positive electrode 41. In other words, when the power applied to the positive electrode 41 corresponds to 50% of the drying power (Pd) and the reflectance of the electric field is less than or equal to a predetermined ratio, the power supply unit 43 can apply power corresponding to 100% of the drying power Pd according to a control instruction of the control unit 100.

[0318] For example, when the reflectance of the electric field is 5% or less, the control unit 100 can apply a preset drying power Pd to the positive electrode 41 through the power supply unit 43. For example, the drying power Pd can be 4000 W.

[0319] Meanwhile, in the third power increase step (S37), the rotational speed W3 of the drum 20 can maintain the rotational speed W of the drum 20 in the previous step. In other words, if the rotational speed of the drum 20 is decreased, the decreased rotational speed (W3 = (0.9) n × W2) of the drum 20 is maintained, and if there is no rotational speed decrease after the drying entry step (S31), the startup rotational speed Wi (W3 = Wi) can be maintained.

[0320] After the third power increase step (S37), the control unit 100 can obtain the reflectance through the matcher 42. In other words, the matcher 42 can measure the electric field reflection wave reflected from the articles to be dried and returned, and the control unit 100 compares it with the electric field incidence wave generated from the positive electrode 41 to obtain the reflectance of the electric field (S38).

[0321] In this case, when the reflectance of the electric field exceeds a predetermined ratio, the control unit 100 can decrease the rotational speed W of the drum 20. For example, when the reflectance of the electric field exceeds 5%, the rotational speed of the drum 20 can be decreased by 10% (S38a). In other words, the rotational speed W of the drum 20 can be 90% of the startup rotational speed (W = 0.9 × W3).

[0322] Then, the control unit 100 can repeat the process of decreasing the rotational speed of the drum 20 until the electric field reflectance of the drum 20 is less than or equal to a predetermined ratio. If the rotational speed is decreased n times, the rotational speed W of the drum 20 can be (0.9) n × W3 (W = (0.9) n × W3).

[0323] On the other hand, when the reflectance of the electric field is less than or equal to a predetermined ratio, the control unit 100 can perform a rotation maintaining step (S39). For example, when the reflectance of the electric field is 5% or less, the rotation maintaining step (S39) can be performed.

[0324] In the rotation maintaining step (S39), the control unit 100 can apply the drying power Pd to the positive electrode 41 and maintain the rotational speed of the drum 20 to dry the articles to be dried. In other words, when the drying power Pd is applied to the positive electrode 41 and the reflectance of the electric field reflected from the articles to be dried is less than or equal to a predetermined ratio, the control unit 100 can maintain the rotational speed of the drum 20.

[0325] Specifically, in the rotation maintaining step S39, the control unit 100 can continuously maintain the drying power Pd applied to the positive electrode 41 in the third power increasing step (S37). Also, in the rotation maintaining step (S39), the final rotational speed Wf of the drum 20 can maintain the rotational speed W of the drum 20 in the previous step. In other words, if the rotational speed of the drum 20 is decreased in the previous step, the decreased rotational speed of the drum 20 (Wf = (0.9) n × W3) is maintained, and if the drum 20 is not decreased after the drying entering step (S31), the starting rotational speed Wi (Wf = Wi) can be maintained.

[0326] With this configuration, the control method of the laundry dryer according to the embodiment of the present application has an effect of removing moisture from the articles to be dried by dielectric heating of the inside of the articles to be dried, preventing local overheating of the articles to be dried by rotation of the drum 20, and preventing color transfer by maintaining the temperature of the articles to be dried at 50 degrees Celsius or less.

[0327] In particular, in the dielectric heating type dryer in which the positive electrode 41 is fixed and the drum 20 is rotated, the control method of the laundry dryer according to the embodiment of the present application can have an effect of heating the articles to be dried accommodated in the drum while the drum is rotated.

[0328] In this case, since the reflectance of the electric field is reduced by controlling the rotational speed of the drum and the RF power, the drying process can be immediately started without a separate impedance matching time, thus having an effect of saving time and energy required for impedance matching.

[0329] In addition, there is also an effect of preventing damage to equipment (such as a matcher) due to a reflected wave.

[0330] In addition, in the drying step (S30), the articles to be dried can be contacted with the lifter 25 at least once by the rotation of the drum 20, and the effect of preventing local overheating can be increased when the articles to be dried are mixed by the lifter 25.

[0331] Meanwhile, in the drying step (S30), the control unit 100 can drive the circulation fan 33 to discharge the humid air existing in the drum 20 to the outside. Meanwhile, the air outside the drum 20 can be introduced into the drum 20.

[0332] With this configuration, the water vapor of the articles to be dried can be evaporated by the air flow. In addition, the overheated positive electrode 41 and the matcher 42 can be cooled by this air flow.

[0333] Meanwhile, as another embodiment, in the drying step (S30), the control unit 100 can measure the temperature of the articles to be dried through the sensor unit 101, and when the temperature of the articles to be dried is equal to or higher than a preset reference temperature, the control unit can control the rotation speed of the drum 20 to maintain the internal temperature of the articles to be dried at 50 degrees or less.

[0334] Meanwhile, in the agitation step (S40), the control unit 100 can cut off the power applied to the positive electrode 41, and rotate the drum 20 to mix the articles to be dried.

[0335] Specifically, in the agitation step (S40), the control unit 100 cuts off the power applied in the drying step (S30) to stop the dielectric heating, and the drum 20 can rotate at a preset agitation rotation speed w m .

[0336] With this configuration, overheating due to long-term use of the power supply unit 43 can be prevented, and at the same time, the effect that the articles to be dried can be uniformly mixed and heated.

[0337] In this case, the rotation speed of the drum 20 in the agitation step (S40) is faster than the rotation speed of the drum 20 in the drying step (S30). In other words, the drying rotation speed wd is less than the agitation rotation speed w m . For example, the agitation rotation speed w m may be 30 rpm.

[0338] On the other hand, in a conventional hot air supply type dryer, the drum is constantly rotated at a speed of 50 rpm in order to uniformly supply hot air to the articles to be dried during the drying process.

[0339] In this case, the articles to be dried are rotated and move upward inside the drum under the action of centrifugal force, and then descend under the action of gravity. In this case, by increasing the contact area with hot air when the articles to be dried fall, the drying performance can be improved, but there is a problem that the articles to be dried are shrunk due to mechanical force.

[0340] In contrast, in the dielectric heating type dryer, the inside of the article to be dried is heated, and it is necessary to mix and heat the article to be dried uniformly, but it is not necessary to generate a falling motion that causes the article to be dried to shrink.

[0341] In other words, in the dielectric heating type dryer, it is necessary to reduce the shrinkage of the article to be dried by preventing the article to be dried from falling during the agitation of the article to be dried.

[0342] To solve this problem, in the agitation step (S40) according to the embodiment of the present application, the control unit 100 controls the drum motor 51 to rotate the drum 20 at a rotational speed of less than 50 rpm. In other words, in the agitation step (S40) according to the embodiment of the present application, the agitation rotational speed w m is less than 50 rpm.

[0343] Specifically, in the agitation step (S40), the agitation rotational speed w m may be obtained in the following manner.

[0344] In the agitation step (S40), when the drum motor 51 is driven by the instruction of the control unit 100, the drum 20 rotates around the rotational axis, and the article to be dried can move along the inner circumferential surface of the drum 20.

[0345] Specifically, that is, the rotational axis of the drum 20 can be disposed in parallel with the ground, or can be disposed at a predetermined angle with the ground. In this case, when the article to be dried is put into the drum 20, the article to be dried is gathered in the portion of the drum 20 close to the ground under the action of gravity. In addition, at least a portion of the article to be dried is in contact with the inner circumferential surface of the drum 20. In addition, the article to be dried is in a state of being pressed by the weight at the inner circumferential surface of the drum 20.

[0346] When the drum 20 starts to rotate, the inner circumferential surface of the drum 20 in contact with the article to be dried starts to rotate. In this case, the article to be dried also rotates around the rotational axis of the drum 20 together with the inner circumferential surface of the drum under the action that the article to be dried presses the inner circumferential surface of the drum 20 by the gravity or the inertial force.

[0347] In this case, the maximum speed of the article to be dried can be the speed of the drum 20. However, the speed of the article to be dried can be reduced due to the gravity, air resistance, etc.

[0348] As a result, when the radius of the drum 20 is r, the article to be dried contained in the drum 20 rotating at the agitation rotational speed w m The maximum speed v of the article to be dried in the drum 20 rotating at the agitation rotational speed w mthe product of v = r x w m ).

[0349] Therefore, when the mass of the article to be dried is m, the maximum kinetic energy (Ek) of the article to be dried in the agitating step (S40) is as follows.

[0350]

[0351] On the other hand, when the article to be dried moves upward along the inner circumferential surface of the drum in the direction of gravity by the rotation of the drum 20, a potential energy Ep can be generated from the point close to the ground to the height difference h of the position where the article to be dried moves in the drum 20. Therefore, when the article to be dried moves by the drum, the potential energy Ep is as follows.

[0352] Ep = mgh

[0353] In this case, in order for the article to be dried to move downward, the potential energy Ep must be greater than the kinetic energy Ek (Ep > Ek).

[0354]

[0355] Further, even if the potential energy Ep is greater than the kinetic energy Ek, in the case where the point is too high inside the drum 20, falling due to gravity can occur. Therefore, at an appropriate height h, the potential energy Ep must be greater than the kinetic energy Ek. In other words, when the cross section (circle) of the drum 20 is considered as a reference, even if a part of the article to be dried moves to the upper semicircular region of the drum 20, falling motion due to gravity can occur. Therefore, the entire article to be dried must have a potential energy Ep greater than the kinetic energy Ek in the lower semicircular region of the drum 20.

[0356] In this case, considering that in the present embodiment, the positive electrode 41 is formed in a range of 120 degrees with respect to the rotation axis of the drum 20, and the article to be dried is heated in the range of the positive electrode 41, it can be seen that the article to be dried is distributed in a range of up to 120 degrees with respect to the rotation axis of the drum 20. In other words, it can be seen that it is symmetrically distributed in a range of 60 degrees based on the vertical line. Therefore, in order for all of the articles to be dried to be located in the lower semicircular region of the drum 20, the article to be dried must move only in a range of 30 degrees based on the rotation axis of the drum 20.

[0357] The height h in this case is summarized as follows using the radius r of the drum 20.

[0358]

[0359] Therefore, if set as the above formula, the agitating rotation speed w mmay have the following range.

[0360]

[0361] In other words, the square of the agitation rotational speed can be set in inverse proportion to the radius of the drum.

[0362] The value obtained by multiplying the radius of the drum by the square of the agitation rotational speed (rad / s) can be 0.27 times or less the magnitude of the acceleration due to gravity.

[0363] For example, if the radius r of the drum 20 is 30 cm and the agitation rotational speed w m may be about 28.4 rpm.

[0364] However, the above range means that the speed of the articles to be dried does not decrease due to gravity, air resistance, etc., and when the moving speed of the articles to be dried decreases due to gravity, air resistance, etc., even if the agitation rotational speed w m is increased, the falling motion of the articles to be dried does not occur. Accordingly, the difference in rotational speed in this regard is included in the spirit and scope of the present application.

[0365] Thus, in the case where the falling motion of the articles to be dried does not substantially occur, the agitation rotational speed w m may be 30 rpm or less.

[0366] With this configuration, when the drum 20 is rotated at the agitation rotational speed w m , the articles to be dried can slide along the inner circumferential surface of the drum.

[0367] On the other hand, Figure 17 is a graph showing the difference in shrinkage rate generated according to time when the control method of the laundry dryer according to an embodiment of the present application is applied.

[0368] The graph shows the shrinkage rate of cotton when the drum is rotated at 30 rpm or less for the entire period (0 minutes), rotated at 50 rpm for the first 20 minutes and then rotated at 30 rpm or less, rotated at 50 rpm for the first 40 minutes and then rotated at 30 rpm or less, and rotated at 50 rpm for the entire period (80 minutes).

[0369] In other words, as the time of the falling motion occurring as the drum is rotated at 50 rpm increases, the shrinkage rate also increases in proportion. Therefore, if the drum 20 is driven at 30 rpm or less in all the agitation steps (S40), the shrinkage rate of the articles to be dried (generally about 4 to 5%) can be reduced to 1.5%.

[0370] Accordingly, according to the present application, it is possible to reduce the shrinkage of the articles to be dried due to mechanical force by preventing the falling motion of the articles to be dried.

[0371] Meanwhile, in the agitation step (S40), the control unit 100 can drive the circulating fan 33 to discharge the humid air present in the drum 20 to the outside. At the same time, the air outside the drum 20 can be introduced into the drum 20.

[0372] With this configuration, the water vapor evaporation of the articles to be dried can be induced by the air flow. In addition, the overheated positive electrode 41 and the matcher 42 can be cooled by this air flow.

[0373] In the agitation step (S40), the control unit 100 can stop applying the RF power for a preset agitation time tm and rotate only the drum 20. For example, the control unit 100 can stop applying the RF power and rotate only the drum 20 for a period of 3 seconds or more and 7 seconds or less, preferably for a period of 5 seconds, and then rotate only the drum 20.

[0374] Meanwhile, the drying step (S30) and the agitation step (S40) are repeated until a preset dryness is reached (S50). In this case, the dryness can be determined based on the load of the articles to be dried according to whether the load of the articles to be dried in the drying preparation step (S10) is reduced to a preset level, and the dryness can be determined by the temperature change or humidity inside the drum. In addition, the dryness can also be determined by calculating the time required for drying by considering the applied RF power and the heat capacity of each material of the articles to be dried. For example, the drying step (S30) and the agitation step (S40) can be repeatedly performed 36 times for 1 hour.

[0375] Referring to Figure 15 , considering the temperature change of the articles to be dried to which the control method of the laundry dryer according to the embodiment of the present application is applied, the temperature difference from the first cycle to the last 36th cycle is very small, and it can be seen that the temperature is maintained below 50 degrees.

[0376] Accordingly, according to the present application, the control unit 100 has the effect of maintaining the internal temperature of the articles to be dried below 50 degrees to prevent color transfer from occurring in the articles to be dried.

[0377] Meanwhile, in the cooling step (S60), when the laundry reaches the preset dryness, the control unit 100 cools the laundry. The cooling refers to a process of drying the laundry by using the circulating fan 33 without operating the electric field generator 40. In other words, when the laundry reaches the preset dryness, the control unit 100 drives the circulating fan 33 for a predetermined time and rotates the drum 20. Thereby, the laundry accommodated in the drum 20 is rotated along the drum 20, and the laundry is dried according to the air flow formed by the circulating fan 33.

[0378] After the cooling step (S60), the overall drying process of the laundry dryer according to the embodiment of the present application is completed.

[0379] Although the present application has been described in detail by specific embodiments, it is intended to describe the present application in detail, and the present application is not limited thereto. It is obvious that those skilled in the art can modify or improve the present application within the scope of the technical spirit of the present application.

[0380] All simple modifications or changes of the present application belong to the scope of the present application, and the specific protection scope of the present application will be interpreted by the appended claims.

Claims

1. A clothes dryer, comprising: chassis; A roller is rotatably mounted in the housing to hold the items to be dried; as well as An electric field generator, spaced apart from the drum, is configured to generate an electric field inside the drum when powered. The electric field generator includes: A positive electrode, spaced apart from the drum, is fixed to the housing and configured to apply an electric field to the object to be dried contained in the drum; A power supply unit is configured to supply power to the positive electrode; and A matching circuit, housed within the chassis, is configured to match the power supply impedance with the load-side impedance. The drum is configured to rotate at a preset agitation speed when power supply to the positive electrode is stopped. The positive electrode is formed as an arc shape encompassing a predetermined angular range with the rotation axis of the roller as the origin. The roller is a negative electrode that generates an electric field between itself and the positive electrode. When power is applied to the positive electrode, the roller rotates at a preset drying speed. The stirring speed is greater than 0 rpm and less than 50 rpm, and is greater than the drying speed.

2. The clothes dryer according to claim 1, wherein, Multiplying the radius of the drum by the square of the agitation speed (rad / s) yields a value that is 0.27 times or less of the acceleration due to gravity.

3. The clothes dryer according to claim 1, wherein, The stirring speed is greater than 0 rpm and less than 30 rpm.

4. A clothes dryer, comprising: chassis; A roller is rotatably mounted in the housing to hold the items to be dried; as well as An electric field generator, spaced apart from the drum, generates an electric field inside the drum when powered. The electric field generator includes: A positive electrode, spaced apart from the drum, is fixed to the housing and applies an electric field to the object to be dried contained in the drum; A power supply unit that supplies power to the positive electrode; and A matching circuit, housed within the chassis, matches the power supply impedance to the load-side impedance. The positive electrode is formed as an arc shape encompassing a predetermined angular range with the rotation axis of the roller as the origin. The drum is a negative electrode that generates an electric field between itself and the positive electrode. When power is not applied to the positive electrode, the drum rotates at a preset agitation speed. When power is applied to the positive electrode, the drum rotates at a preset drying speed, where the agitation speed is greater than the drying speed. When the drum rotates at the agitation speed, the object to be dried slides along the inner circumferential surface of the drum.

5. A control method for a clothes dryer, the clothes dryer comprising a drum for accommodating items to be dried and a positive electrode spaced apart from the drum, the positive electrode being used to generate an electric field in the drum, the control method comprising: The drying step involves applying power to the fixed positive electrode and rotating the drum at a preset drying speed. as well as The agitation step involves cutting off the power applied to the positive electrode and rotating the drum. The roller is a negative electrode that generates an electric field between itself and the positive electrode. The positive electrode is formed as an arc shape surrounding a predetermined angular range with the rotation axis of the roller as the origin. In the agitation step, the drum rotates at a preset agitation speed, which is greater than 0 rpm and less than 30 rpm, and is greater than the drying speed.

6. The control method for a clothes dryer according to claim 5, wherein, The square of the agitation speed is inversely proportional to the radius of the drum.

7. The control method for a clothes dryer according to claim 5, wherein, Multiplying the radius of the drum by the square of the agitation speed (rad / s) yields a value that is 0.27 times or less of the acceleration due to gravity.

8. The control method for a clothes dryer according to claim 5, wherein, In the agitation step, the drum rotates for a preset agitation time, and the agitation time is more than 3 seconds and less than 7 seconds.

9. The control method for a clothes dryer according to claim 5, wherein, In the drying step, the drying speed is greater than 0 rpm and less than or equal to 7 rpm.

10. The control method for a clothes dryer according to claim 5 further includes: Prior to the drying step, a load sensing step is performed by rotating the roller to sense the load on the object to be dried. In the load sensing step, the drum rotates at the agitation speed.

Images