Clothes dryer

Abstract

A clothes dryer includes: a cabinet; a drum configured to rotate in the cabinet; a plurality of electrodes between the cabinet and the drum; a radio frequency (RF) power supply configured to apply a voltage to the plurality of electrodes to generate an electric field for dielectric heating of an object accommodated in the drum; and at least one lifter provided in the drum, formed of a metal material, electrically floated, and configured to rotate with the drum, each of the at least one lifter including a first portion in contact with the drum and a second portion bent from the first portion and facing an inner side of the drum.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation of International Application No. PCT / KR2024 / 005917, filed on May 2, 2024, which is based on and claims priority to Korean Patent Application No. 10-2023-0086110, filed on Jul. 3, 2023, and Korean Patent Application No. 10-2023-0166130, filed on Nov. 24, 2023, in the Korean Intellectual Property Office, the disclosures of which are incorporated by reference herein in their entireties.BACKGROUND1. Field

[0002] The disclosure relates to a clothes dryer, and more particularly, to a clothes dryer capable of drying an object through dielectric heating.2. Description of Related art

[0003] A dryer is a device that dries laundry with hot dry air. The dryer is configured to dry an object to be dried by rotating a drum in which the object to be dried is received at a low speed while allowing hot air to pass inside the drum.

[0004] The dryer includes a cabinet that forms an exterior thereof, a drum rotatably installed inside the cabinet, a drive device that drives the drum, and a hot air supplier that supplies hot air into the rotating drum.

[0005] When the dryer is operated after inserting the object to be dried into the drum, the drum is rotated by the operation of the drive device, and at the same time, hot air is supplied to the drum through the hot air supplier, thereby drying the object inside the drum.

[0006] Such a drying method of rotating the drum has a problem of causing damage to the laundry, such as abrasion and shrinkage. In recent years, research has been continuously conducted on drying an object to be dried while reducing damage to the laundry.SUMMARY

[0007] Provided is a clothes dryer capable of uniformly drying an object to be dried through dielectric heating.

[0008] Further, provided is a clothes dryer capable of reducing capacitance variation of electrodes according to rotation of an object to be dried inside a drum.

[0009] Further still, provided is a clothes dryer having an electrically floating lifter inside a drum.

[0010] Further still, provided is a clothes dryer capable of improving capacitance through an electrically floating lifter inside a drum.

[0011] Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments.

[0012] According to an aspect of the disclosure, a clothes dryer includes: a cabinet; a drum configured to rotate in the cabinet; a plurality of electrodes between the cabinet and the drum; a radio frequency (RF) power supply configured to apply a voltage to the plurality of electrodes to generate an electric field for dielectric heating of an object accommodated in the drum; and at least one lifter provided in the drum, formed of a metal material, electrically floated, and configured to rotate with the drum, each of the at least one lifter including a first portion in contact with the drum and a second portion bent from the first portion and facing an inner side of the drum.

[0013] Adjacent electrodes of the plurality of electrodes may be separated by a first gap, and a first length of the first portion may be shorter than the first gap.

[0014] The at least one lifter may include a plurality of lifters, and the first gap is overlapped by one or more of the plurality of lifters.

[0015] The plurality of lifters may be at regular intervals in a circumferential direction inside the drum.

[0016] A second length of the second portion may be smaller than a radius of the drum.

[0017] A first angle between the drum and the second portion may be at least 90 degrees.

[0018] The plurality of electrodes may be spaced apart along an outer circumference of the drum.

[0019] The clothes dryer may further include a direct current (DC) power supply configured to provide DC power to the RF power supply.

[0020] The at least one lifter may be fixed to the drum by at least one of adhesion, welding, or screws.

[0021] Adjacent lifters of the plurality of lifters may be separated by a second gap, and the second portion may cover the second gap as the first angle increases.

[0022] The clothes dryer may further include a controller configured to control the RF power supply, the at least one lifter may include a plurality of lifters, and the controller may be further configured to adjust a speed of the drum to compensate for an increase in a friction coefficient of an inner wall of the drum according to a number of the plurality of lifters.

[0023] The controller may be further configured to compensate for the increase in the friction coefficient of the inner wall of the drum by adjusting a rotational direction of the drum in a direction opposite to a bending direction of the second portion.

[0024] According to an aspect of the disclosure a clothes dryer includes: a cabinet; a drum configured to rotate in the cabinet; a plurality of electrodes spaced apart along an outer circumference of the drum between the cabinet and the drum; a radio frequency (RF) power supply configured to apply a voltage to the plurality of electrodes to generate an electric field for dielectric heating of an object accommodated in the drum; a direct current (DC) power supply configured to provide DC power to the RF power supply; and at least one lifter in the drum and configured to rotate with drum, the at least one lifter being electrically floated and being formed of metal without electrical connection.

[0025] Each of the at least one lifter may include: a first portion in contact with the drum, and a second portion bent from the first portion and facing an inner side of the drum.

[0026] The at least one lifter may include a plurality of lifters at regular intervals in a circumferential direction inside the drum.

[0027] Adjacent electrodes of the plurality of electrodes may be separated by a first gap, and a first length of the first portion may be shorter than the first gap.

[0028] A second length of the second portion may be smaller than a radius of the drum.

[0029] A first angle between the drum and the second portion may be at least 90 degrees.

[0030] Adjacent lifters of the plurality of lifters may be separated by a second gap, and the second portion may cover the second gap as the first angle increases.

[0031] The clothes dryer may further include a controller configured to control the RF power supply, and determine a rotational speed of the drum.BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above and other aspects, features, and advantages of certain embodiments of the present disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0033] FIG. 1 is a perspective view of a dryer according to an embodiment;

[0034] FIG. 2 is a cross-sectional view of the dryer of FIG. 1;

[0035] FIG. 3 is a schematic view of electrodes and a lifter according to an embodiment;

[0036] FIG. 4 is a perspective view of a lifter according to an embodiment;

[0037] FIG. 5 is a schematic cross-sectional view of the electrodes and the lifter mounted on the drum of FIG. 3;

[0038] FIG. 6 is an enlarged view of portion A of FIG. 5, illustrating the lifter according to an embodiment;

[0039] FIG. 7 is a control block diagram of a dryer according to an embodiment;

[0040] FIGS. 8 and 9 are views of the change in capacitance caused by the rotation of a lifter according to the number of lifters, according to an embodiment; and

[0041] FIG. 10 is a schematic view of an arrangement structure of electrodes according to an embodiment.DETAILED DESCRIPTION

[0042] Various embodiments of the disclosure and terms used herein are not intended to limit the technical features described herein to specific embodiments, and should be understood to include various modifications, equivalents, or substitutions of the corresponding embodiments.

[0043] In describing of the drawings, similar reference numerals may be used for similar or related elements.

[0044] The singular form of a noun corresponding to an item may include one or more of the items unless clearly indicated otherwise in a related context.

[0045] In the disclosure, phrases, such as “A or B”, “at least one of A and B”, “at least one of A or B”, “A, B or C”, “at least one of A, B and C”, and “at least one of A, B, or C” may include any one or all possible combinations of the items listed together in the corresponding phrase among the phrases.

[0046] Terms such as “first”, “second”, “primary”, or “secondary” may be used simply to distinguish an element from other elements, without limiting the element in other aspects (e.g., importance or order).

[0047] When an element (e.g., a first element) is referred to as being “(functionally or communicatively) coupled” or “connected” to another element (e.g., a second element), the first element may be connected to the second element, directly (e.g., wired), wirelessly, or through a third element.

[0048] It will be understood that when the terms “includes”, “comprises”, “including”, and / or “comprising” are used in the disclosure, they specify the presence of the specified features, figures, steps, operations, components, members, or combinations thereof, but do not preclude the presence or addition of one or more other features, figures, steps, operations, components, members, or combinations thereof.

[0049] When a given element is referred to as being “connected to”, “coupled to”, “supported by” or “in contact with” another element, it is to be understood that it may be directly or indirectly connected to, coupled to, supported by, or in contact with the other element. When a given element is indirectly connected to, coupled to, supported by, or in contact with another element, it is to be understood that it may be connected to, coupled to, supported by, or in contact with the other element through a third element.

[0050] It will also be understood that when an element is referred to as being “on” another element, it may be directly on the other element or intervening elements may also be present.

[0051] As used herein, the term “and / or” includes any and all combinations of one or more of the associated listed items.

[0052] A washing machine according to various embodiments may include a housing for accommodating various components therein. The housing may be provided in the form of a box having a laundry opening formed on one side.

[0053] Hereinafter, a clothes dryer according to various embodiments will be described in detail with reference to the accompanying drawings.

[0054] FIG. 1 is a perspective view of a clothes dryer according to an embodiment, and FIG. 2 is a cross-sectional view of the clothes dryer of FIG. 1.

[0055] As shown in FIGS. 1 and 2, a clothes dryer 1 may include a cabinet 1a that forms an exterior thereof, and a drum 20 rotatably installed within the cabinet 1a.

[0056] The cabinet 1a may be provided in a substantially hexahedral shape. The cabinet 1a may include an upper cover 1b forming an upper surface, a front cover 1c forming a front surface, and a base 1d forming a lower surface.

[0057] The front cover 1c, the upper cover 1b, and the base 1d forming the cabinet 1a may each be provided separately and assembled. As another example, some configurations forming the cabinet 1a (e.g., the front cover, the upper cover, the base) may be formed integrally.

[0058] The front of the cabinet 1a may be provided with an opening 31 for loading or unloading laundry such as clothes, which is an object to be dried, into or out of the drum 20.

[0059] The clothes dryer 1 may include a door 50 configured to open or close the opening 31 formed in the front cover 1c. After opening the door 50, a user may insert or remove the object to be dried into or from the drum 20 through the opening 31. When the opening 31 is closed and operation of the clothes dryer 1 begins, a door lock may lock the door 50.

[0060] On an upper front side of the cabinet 1a, a user interface 10 for interaction between a user and the clothes dryer 1 may be provided. The user interface 10 may obtain user input and may display various information about the clothes dryer 1.

[0061] The location of the user interface 10 is not limited to the front. The user interface 10 may be provided at different locations on the clothes dryer 1.

[0062] The user interface 10 may include a display. For example, the user interface 10 may include an inputter for acquiring user input regarding the operation of the clothes dryer 1. The inputter may include a rotatable dial and different buttons. For example, the user interface 10 may include various forms of inputter and displays.

[0063] The display may be provided as various types of display panels. For example, the display may include a liquid crystal display (LCD) panel, a light emitting diode (LED) panel, an organic light emitting diode (OLED) panel, or a micro LED panel. The display may also be used as an input device by including a touch screen.

[0064] The display may display information input by the user or information provided to the user on various screens. The display may display information related to the operation of the clothes dryer 1 as at least one of an image or text. For example, the display may display a graphic user interface (GUI) that enables control of the clothes dryer 1. In other words, the display may display user interface (UI) elements such as icons.

[0065] The inputter may transmit an electrical signal (voltage or current) corresponding to the user input to a controller 200. The inputter may include various buttons and / or dials. For example, the inputter may include at least one of a power button for turning the power of the clothes dryer 1 on or off, a start / stop button for starting or stopping a drying operation, a drying course button for selecting a drying course, a temperature button for setting a drying temperature, and a time button for setting a drying time. The various buttons may be provided as physical buttons or touch buttons.

[0066] The dial included in the inputter may be rotatable. According to the rotation of the dial, the UI elements shown on the display may be sequentially moved. The clothes dryer 1 may perform drying according to a selected drying course. The drying course may include drying parameters, such as drying temperature and drying time. Different drying courses may be selected according to the position of the object to be dried in the drum 20, the type of the object, and / or the amount of the object.

[0067] The clothes dryer 1 may include a filter 40 detachably mounted on the front cover 1c. The filter 40 may filter out foreign matter, such as lint, that flows with the air circulating inside the drum 20.

[0068] Inside the cabinet 1a, the drum 20 may be provided in a cylindrical shape. The drum 20 may be configured to receive the object to be dried therein so that drying may be performed. The drum 20 may be configured to be rotatable under power from a motor 72. The drum 20 may be provided within the cabinet 1a to be rotatable about a rotating axis that is substantially horizontal to the ground.

[0069] An inner circumferential surface of the drum 20 may be provided with a lifter 100 configured to lift the object to be dried as the drum 20 rotates. According to the rotational speed of the drum 20, the object to be dried may repeat the motion of being lifted and dropped by the lifter 100. A detailed description of the lifter 100 will be described later.

[0070] An outer circumferential surface of the drum 20 may be provided with a roller 22 configured to support the drum 20 to rotate smoothly.

[0071] The drive device may be disposed in a lower inner portion of the cabinet 1a. The drive device may be mounted to the base 1d. The drive device may include a motor 72, and a pulley 74, and a belt 75 for transmitting the power of the motor 72 to the drum 20.

[0072] The pulley 74 may be connected to a rotating shaft 73 connected to the motor 72. When the rotating shaft 73 is rotated by the motor 72, the pulley 74 may rotate together with the rotating shaft 73. The belt 75 may be installed to be wound around an outer surface of the pulley 74 and an outer surface of the drum 20. When the belt 75 is rotated by the driving force of the motor 72, the drum 20 may rotate together with the belt 75. The drum 20 may rotate in a clockwise or counterclockwise direction.

[0073] Inside the cabinet 1a and inside the drum 20, a flow path 80 for circulating air may be formed. The flow path 80 may include an air discharge flow path 81 for discharging air from the inside of the drum 20 to the outside of the drum 20, and an air supply flow path 82 for supplying air into the drum 20.

[0074] The clothes dryer 1 may include a discharge duct 60 that forms the air discharge flow path 81. The filter 40 may be disposed at an inlet 61 of the discharge duct 60. The discharge duct 60 may penetrate the cabinet 1a, and an outlet 63 of the discharge duct 60 may be exposed to the outside of the cabinet 1a. Air entering the inlet 61 of the discharge duct 60 may be filtered as it passes through the filter 40. The filter 40 may filter out foreign matter, such as lint, contained in the air.

[0075] Inside the cabinet 1a, a fan 71 for flowing air may be provided. By rotation of the fan 71, air inside the drum 20 may be introduced into the discharge duct 60. For example, by rotation of the fan 71, air may be supplied into the drum 20 through an air supply flow path 83 and an air inlet 20b of the drum 20. The air supplied to the interior of the drum 20 may be used for drying the object to be dried.

[0076] The motor 72 may rotate the drum 20 as well as the fan 71. Although the drum 20 and the fan 71 are illustrated as being driven by a single motor 72, the disclosure is not limited thereto. A separate fan motor for driving the fan 71 may also be provided. For example, the motor 72 may be directly connected to the drum 20 to rotate the drum 20. In a case where the motor 72 is directly connected to the drum 20, the pulley 74 and the belt 75 may be omitted.

[0077] Between the cabinet 1a and the drum 20, a plurality of electrodes may be provided. In FIG. 2, two electrodes 90a and 90b (collectively 90) are shown. The electrodes 90a and 90b may be spaced apart from each other along a perimeter of the drum 20. The electrodes 90a and 90b may be disposed to be spaced apart from the cabinet 1a and the drum 20 as well. When a voltage is applied to the electrodes 90a and 90b, an electric field may be generated inside the drum 20.

[0078] The electric field generated inside the drum 20 may cause a dielectric material (e.g., water molecules) contained in the object to be dried to vibrate. When the dielectric material vibrates, dipole frictional heat may be generated to heat the dielectric material. The heated dielectric material may evaporate, thereby drying the object to be dried. The evaporated dielectric material may be discharged to the outside of the drum 20 along with the air supplied into the drum 20. In the present embodiment, the electrode 90 is shown as two electrodes for example, but is not limited thereto. For example, the electrodes may be spaced apart from each other along the perimeter of the drum, and may divide the cylindrical drum 20 into 2, 3, 6, 12, or 18 sections. The electrodes and the lifter will be described in more detail with reference to FIGS. 3 and 4 below.

[0079] FIG. 3 is a view schematically of electrodes and a lifter according to an embodiment, FIG. 4 is a perspective view of a lifter according to an embodiment, FIG. 5 is a cross-sectional view of the electrodes and the lifter mounted on the drum, of FIG. 3, and FIG. 6 is an enlarged view of portion A of FIG. 5, illustrating the lifter according to an embodiment.

[0080] As shown in FIGS. 3 to 6, a plurality of electrodes 90 may be spaced apart from each other along the perimeter of the drum 20. Each of the plurality of electrodes 90 may be provided in a plate shape having a curvature.

[0081] The plurality of electrodes 90 may be disposed along the perimeter of the drum 20 with two electrodes 90a and 90b opposite each other. The plurality of electrodes 90 may be spaced apart at regular intervals (or regular distances). The plurality of electrodes 90 may be electrically connected to a radio frequency (RF) power supply 220 on the outside of the drum 20. The plurality of electrodes 90 may be provided as fixed electrodes.

[0082] The plurality of electrodes 90 may be provided as a first electrode 90a and a second electrode 90b. The first electrode 90a may be disposed on an upper side of the drum 20, and the second electrode 90b may be disposed on a lower side of the drum 20 adjacent to the first electrode. The first electrode 90 and the second electrode 90 may have a first gap G1 therebetween. The first gap G1 may be provided between the first electrode 90 and the second electrode 90.

[0083] The plurality of electrodes 90 may be fixed between the cabinet 1a and the drum 20. Since the drum 20 is not connected to the plurality of electrodes 90, the plurality of electrodes 90 may not restrict rotation of the drum 20. Furthermore, since the plurality of electrodes 90 are disposed along the perimeter of the drum 20, the plurality of electrodes 90 may generate an electric field in various areas within the drum 20. Thus, the clothes dryer 1 according to the disclosure may generate an electric field inside the drum 20 via the plurality of electrodes 90 even while the drum 20 is rotating, and may perform drying of the object to be dried.

[0084] On the other hand, in the conventional method, electrodes were placed inside the drum or the drum 20 and the electrodes were electrically connected using wiring, thereby restricting the rotation of the drum 20 to prevent the connection between the drum 20 and the electrodes from being broken. Furthermore, in the conventional method, an electric field was generated only in a fixed area within the drum 20, so that drying by dielectric heating would not occur when the object to be dried is moved out of the electric field.

[0085] The clothes dryer 1 of the embodiment may provide an electrically floating lifter 100 inside the drum 20. The lifter 100 may be configured to increase the capacitance of the electrode 90 and reduce the capacitance variation due to tumble driving of the object to be dried inside the drum 20. The lifter 100 may be configured to raise the capacitance of the plurality of electrodes 90. The lifter 100 may be configured to minimize the rate of capacitance variation according to the behavior of the object to be dried inside the drum.

[0086] The lifter 100 may create an electric field inside the drum 20. The lifter 100 may implement the shape of an electrode inside the drum 20. The lifter 100 may implement the electric field characteristics inside the drum 20.

[0087] The lifter 100 may be provided electrically floating within the drum 20. The lifter 100 may be made of a floating metallic material that is not electrically connected within the drum 20. The lifter 100 may be electrically floating. The lifter 100 may be made of a metal that is not connected circuitously. The lifter 100 may have unspecified characteristics. The lifter 100 may include a conductive metal. The lifter 100 may be a metal with no connections. The lifter 100 may be provided with a floating potential.

[0088] The lifter 100 may be provided in an electrically floating state inside the drum 20, and the plurality of electrodes 90 may be provided outside the drum 20 in electrical connection with the RF circuitry.

[0089] The lifter 100 may be provided in an electrically floating state inside the drum 20 and may not have any specific electrodes. The lifter 100 may be provided electrically floating inside the drum 20 to minimize the rate capacitance variation according to the behavior of the object to be dried inside the drum. The lifter 100 may be provided symmetrically on the inside of the drum 20 relative to the plurality of electrodes 90 on the outside of the drum 20. The lifter 100 may function as a capacitor inside the drum 20. The lifter 100 may lower the impedance inside the drum 20 to help the drive circuitry.

[0090] The electrode impedance may vary according to a variety of factors, such as the amount of the object to be dried, the type of the object, the size of the object, the amount of water contained in the object, and the distribution state of the object.

[0091] The lifter 100 may substitute for the impedance of the rotating object to be dried inside the drum 20. The lifter 100 may be provided as a floating metal material inside the drum 20 so that the impedance may remain constant. The lifter 100 may keep the impedance of the rotating object to be dried inside the drum 20 constant. The lifter 100 may allow the impedance to remain constant by minimizing the fluctuations in the capacitor value of the rotating object to be dried inside the drum 20. For example, when the dielectric constant of air inside the drum is 1, a dielectric constant of water may be 80, and a dielectric constant of a water-soaked object to be dried may be 80 or more. The rotation of such objects may cause the capacitance to fluctuate. The lifter 100 mounted inside the drum 20 may substitute for the variation in capacitance due to the rotation of the drum. Thus, the lifter 100 may configured to reduce the rate of the capacitance variation according to the behavior of the object to be dried inside the drum 20, and to increase the absolute size to reduce the burden on the drive circuitry, e.g., the matching circuit.

[0092] The lifter 100 may be a rotating body structure inside the drum 20 that increases the capacitance of the fixed plurality of electrodes 90 and improves the characteristics of reducing the fluctuating value of the capacitance.

[0093] The lifter 100 may include a first portion 110 attached to an inner surface of the drum 20, and a second portion 120 bent from the first portion 110 and facing an inner side of the drum 20. The lifter 100 may include a shape bent into a substantially “L” shape. One side of the lifter 100 may be in contact with and attached to the inner surface of the drum 20, and the other side may be configured to protrude into the interior of the drum 20 to act as a lifter to control the rotational and / or falling behavior of the object to be dried in the clothes dryer.

[0094] The lifter 100 may be fixed to the drum 20. At least a portion of the lifter 100 may be attached to the inner surface of the drum 20. The lifter 100 may be fixed to the drum 20 via a separate member, such as adhesive, welding, or screws.

[0095] The lifters 100 may be provided in a plurality inside the drum 20. The plurality of lifters 100 may be spaced apart inside the drum 20 at regular intervals (or regular distances). The plurality of lifters 100 may be spaced apart in a circumferential direction inside the drum 20. The plurality of lifters 100 may be spaced apart from each other by a second gap G2. The plurality of lifters 100 may be spaced apart at uniform intervals (or uniform distances) inside the drum 20. In the embodiment, 18 lifters are shown spaced apart from each other, but embodiments are not limited thereto. The number of lifters may be varied.

[0096] The first portion 110 of the lifter 100 may be fixed to the inner surface of the drum 20. The first portion 110 of the lifter 100 may be in contact with the inner surface of the drum 20. The first portion 110 may be attached to the inner surface of the drum 20. The first portion 110 may be installed on the inner surface of the drum 20 via bonding, welding, or a separate member.

[0097] The first portion 110 of the lifter 100 may be formed in a substantially rectangular plate shape. The first portion 110 may be formed with a first depth d2 corresponding to a first depth d1 of the drum 20. The first portion 110 of the lifter 100 may have a first length L1. The first length L1 of the first portion 110 may be shorter than the first gap G1 between the plurality of electrodes 90.

[0098] The first length L1 of the first portion 110 may be shorter than the first gap G1 between the plurality of electrodes 90, so that during the rotation of the drum 20, the first portion 110 of the lifter 100 may be positioned in the first gap G1 between the electrode 90 and the electrode 90. Since the first length L1 of the first portion 110 is shorter than the first gap G1, the first portion 110 of the lifter 100 may always be positioned within the first gap G1, resulting in uniform variation characteristics.

[0099] In a case where the first length L1 of the first portion 110 of the lifter 100 is be longer, the first portion 110 of the lifter 100 may or may not be positioned in the first gap G1 between the electrodes, resulting in inconsistent variations.

[0100] The second portion 120 of the lifter 100 may be formed by being bent from the first portion 110. The second portion 120 may extend integrally from the first portion 110. The second portion 120 may have a second length L2.

[0101] The second length L2 of the second portion 120 may be provided with a length that does not affect the behavior of the object to be dried inside the drum 20. The second length L2 may be provided at a level of 10% of the diameter of the drum 20.

[0102] A first angle θ1 may be formed between the first portion 110 and the second portion 120 of the lifter 100. The first angle θ1 may be approximately 90 degrees or more. The first angle θ1 may be greater than perpendicular to the inner surface of the drum 20.

[0103] As the first angle θ1 of the lifter 100 increases, the lifter 100 may be formed such that the second portion 120 of the lifter 100 covers the first gap G1. Through this configuration, the capacitance of the external electrode 90 may be increased and the amount of variation may be reduced. For example, the second portion 120 of the lifter 100 may overlap the neighboring first portion 110 according to the first angle θ1 to cover the first gap G1.

[0104] As the second portion 120 of the lifter 100 covers the first gap G1 between the plurality of electrodes 90, the capacitance of the electrodes 90 may be increased, and the effect of reducing the amount of variation may be maximized.

[0105] FIG. 7 is a control block diagram of a clothes dryer according to an embodiment. In the following, any description that is redundant with the above description will be omitted.

[0106] As shown in FIG. 7, the clothes dryer 1 may include the motor 72 that rotates the drum 20 and the fan 71, an RF power supply 220 that applies a voltage to the plurality of electrodes 90 disposed around the drum 20, and the controller 200 that controls the RF power supply 220 to generate an electric field for dielectric heating of the object to be dried accommodated within the drum 20 via the plurality of electrodes 90.

[0107] The clothes dryer 1 may include the user interface 10, a direct current (DC) power supply 230, and a matching circuit 210.

[0108] The controller 200 may be electrically connected to the configurations of the clothes dryer 1. The controller 200 may enable control of the configurations of the clothes dryer 1. For example, the controller 200 may control the motor 72 to rotate the drum 20 and the fan 71.

[0109] The controller 200 may control the DC power supply 230, the RF power supply 220, and the matching circuit 210 to apply a voltage to the plurality of electrodes 90.

[0110] The user interface 10 may enable user input to be obtained. The user interface 10 may display various information regarding the operation of the clothes dryer 1. The user interface 10 may include an inputter for acquiring user input and a display for displaying the information.

[0111] The DC power supply 230 may convert alternating current (AC) power supplied from a commercial power source S into DC power and deliver the DC power to the RF power supply 220. The RF power supply 220 may generate an RF signal, and may apply the RF signal to the plurality of electrodes 90.

[0112] The matching circuit 210 may be provided between the RF power supply 220 and the plurality of electrodes 90. The RF signal generated by the RF power supply 220 may be delivered to the electrodes 90 via the matching circuit 210. The RF signal may cause a sinusoidal voltage to be applied to the electrodes 90.

[0113] The controller 200 may control the DC power supply 230 to regulate the magnitude of the voltage applied to the electrode 90. As the power supplied to the RF power supply 220 increases, the amplitude of the RF signal may increase, and the magnitude of the voltage applied to the electrode 90 may increase. The magnitude of the voltage may be represented by an effective value. The controller 200 may control the RF power supply 220 to regulate the phase of the voltage applied to the electrode 90. The controller 200 may control the DC power supply 230 to provide power to the electronic components of the clothes dryer 1.

[0114] The matching circuit 210 may match the output impedance of the RF power supply 220 with the electrode impedance of each of the plurality of electrodes 90. The matching circuit 210 may include a variable inductor and a variable capacitor. When there is a difference between the output impedance of the RF power supply 220 and the electrode impedance of the electrode 90s, reflected power may be generated from the electrodes 90, and the power transfer efficiency may be reduced. To minimize the reflected power, it is necessary to perform a matching of the output impedance of the RF power supply 220 and the electrode impedance of the electrode 90. The controller 200 may control the matching circuit 210 to perform impedance matching.

[0115] The electrode impedance may vary according to various factors, such as the amount of the object to be dried, the type of the object, the size of the object, the amount of water contained in the object, and the distribution state of the object.

[0116] For example, when a dielectric material with a high dielectric constant (e.g., water) is present between the plurality of electrodes 90, the strength of the electric field formed between the electrodes 90 may decrease as charge accumulates in the dielectric material. As the strength of the electric field decreases, the magnitude of the voltage detected at the electrode 90 may decrease, and the electrode impedance may decrease. As drying of the object to be dried progresses, the water contained in the object to be dried may be removed, so that the electrode impedance may gradually be detected to be greater.

[0117] The controller 200 may determine the electrode impedance based on the magnitude of the voltage detected at the output terminal of the matching circuit 210. The controller 200 may acquire distribution information of the object to be dried by using the electrode impedance of each of the plurality of electrodes 90. For example, the controller 200 may determine the amount of water (i.e., moisture content) contained in the object to be dried based on the detected electrode impedance. The electrode impedance detected at each of the plurality of electrodes 90 may vary according to the position of the object to be dried within the drum 20.

[0118] For example, when the drum 20 is rotated while the object to be dried is received inside the drum 20, the objects may clump together or disperse, and the electrode impedance detected at each of the plurality of electrodes 90 may be different according to the distribution state of the objects.

[0119] In the event that the electrically floating lifter 100 is provided inside the drum 20, the controller 200 may obtain information of the electrode impedance of the lifter 100. The floating lifter 100, which is not electrically connected to anything inside the drum 20, may have a constant electrode impedance, which may minimize the rate of capacitance variation according to the behavior of the object to be dried inside the drum.

[0120] The controller 200 may adjust the rotational speed of the drum 20 to compensate for an increase in the friction coefficient of the inner wall of the drum 20 according to the number of lifters 100. During the rotation of the drum 20 of the clothes dryer 1, the main behavior of the object to be dried inside may exhibit a “lift-and-fall” motion along the wall of the drum 20. At this time, the behavioral characteristics (e.g., Froude Number) of the object to be dried may have various influencing factors. Among them, the higher the friction coefficient, the better it may move along the inside of the drum 20. When the number of lifters 100 in the drum 20 is increased, the friction coefficient may increase, and thus the controller 200 may maintain the friction coefficient by reducing the rotational speed (rpm) of the drum 20.

[0121] The controller 200 may control the rotational direction of the drum 20 in a direction opposite to the bending direction of the second portion 120 of the lifter 100, e.g., in a direction in which the object to be dried falls inside the drum 20 during the rotation of the drum 20, thereby reducing the surface friction coefficient, preventing the friction coefficient from increasing.

[0122] FIGS. 8 and 9 are views of the change in capacitance caused by the rotation of a lifter according to the number of lifters, according to an embodiment. In the following, any description that is redundant with the above description will be omitted.

[0123] As shown in FIGS. 8 and 9, the lifter 100 may reduce the rate of capacitance variation according to the behavior of the object to be dried inside the drum 20. As the number of lifters 100 is increased, the change in capacitance with rotation of the lifter 100 may be observed. As when the number of lifters 100 is increased, the change in capacitance with rotation of the lifter 100 may be reduced.

[0124] For example, 3 (a), 8 (b), 12 (c), or 18 (d) lifters 100 may be installed in the drum 20. By measuring the change in capacitance when the lifter 100 is at 0°, 10°, 20°, and 30°, respectively, as the drum 20 rotates, the change in capacitance may be determined.

[0125] First, when 3 lifters (a) are installed, it may be seen that the capacitance increases from 2.8 pF to 3.0 pF, 4.5 pF, and 7 pF when the lifter 100 is at 0°, 10°, and 20°. When 3 lifters (a) are installed, the variation of the capacitance may be 311.6%.

[0126] Furthermore, when 8 lifters (b) are installed, it may be seen that the capacitance increases from 3.3 pF to 4.3 pF and then decreases from 3.9 pF to 3.2 pF when the lifter 100 is at 0°, 10°, and 20°. When 8 lifters (b) are installed, the variation of the capacitance may be 43.9%.

[0127] When 12 lifters (c) are installed, it may be seen that the capacitance increases from 2.9 pF to 3.1 pF and then decreases from 3.0 pF to 2.9 pF when the lifter 100 is at 0°, 10°, 20°, and 30°. When 12 lifters (c) are installed, the variation of the capacitance may be 14.4%.

[0128] When 18 lifters (d) are installed, it may be seen that the capacitance (C value) decreases from 3.1 pF to 3.0 pF and is maintained between 3.1 pF and 3.0 pF when the lifter 100 is at 0°, 10°, 20°, and 30°. When 18 lifters (d) are installed, the variation of the capacitance may be 2.96%. For example, when 3 lifters (a) are installed, the variation of the capacitance may be 311.6%, when 8 lifters (b) are installed, the variation of the capacitance may be 43.9%, when 12 lifters (c) are installed, the variation of the capacitance may be 14.4%, and when 18 lifters (d) are installed, the variation of the capacitance may be 2.96%.

[0129] As described above, it may be seen that the more the number of lifters 100 installed inside the drum 20, the less the variation of the capacitance. As the number of lifters 100 increases, the change in capacitance according to the rotation of the lifter 100 may be reduced.

[0130] As shown in an embodiment, the number of lifters 100 is not limited to 18. The number of lifters 100 may vary according to the number of electrodes.

[0131] FIG. 10 is a schematic view of an arrangement structure of electrodes according to an embodiment. In the following, any description that is redundant with the above description will be omitted.

[0132] As shown in FIG. 10, three electrodes 90a, 90b, and 90c may be disposed adjacent to each other and spaced apart along the perimeter of the drum 20. A first electrode 90a may be disposed on an upper right side of the drum 20, a second electrode 90b may be disposed on a lower side of the drum 20 adjacent to the first electrode, and a third electrode 90c may be disposed on an upper left side of the drum 20 adjacent to the first electrode. The number of electrodes is not limited to those illustrated. The number of electrodes may be varied.

[0133] Inside the drum 20, an electrically floating lifter 100 may be provided. The lifters 100 may be spaced apart at regular intervals (or regular distances) inside the drum 20. The lifter 100 may include the first portion 110 that is mounted inside the drum 20 and the second portion 120 that is bent at the first angle θ1 from the first portion 110. The lifter 100, which is electrically floated, may reduce the rate of capacitance variation according to the behavior of the object to be dried inside the drum 20 while increasing its absolute capacitance, thereby reducing the burden on the drive circuitry, e.g., the matching circuit.

[0134] According to the concept of the disclosure, by attaching the electrically floating lifters 100 to the inner wall of the rotating drum 20, the capacitance of the electrodes 90 may be increased, and the capacitance variation according to the rotation of the object inside the drum 20 may be reduced, thereby improving the efficiency of the clothes dryer 1.

[0135] The clothes dryer 1 according to an embodiment may include the cabinet 1a; the drum 20 rotatably provided inside the cabinet 1a; the plurality of electrodes 90 disposed between the cabinet 1a and the drum 20; the RF power supply 220 configured to apply a voltage to the plurality of electrodes 90 to generate an electric field for dielectric heating of an object to be dried accommodated in the drum 20; and the electrically floating lifter 100 made of a metal material and configured to rotate together with the drum 20, the lifter 100 including the first portion 110 in contact with the drum 20 and the second portion 120 bent from the first portion 110 and facing an inner side of the drum 20. According to the disclosure, the lifter may reduce the capacitance variation according to the rotation of the object inside the drum. For example, the efficiency of the clothes dryer may be improved by increasing the capacitance of the electrodes 90.

[0136] The plurality of electrodes 90 may include the first gap G1 between adjacent electrodes 90, and the first length L1 of the first portion may be shorter than the first gap G1. The first gap may be overlapped by at least one or more of the lifters.

[0137] A plurality of lifters may be provided and be disposed at regular intervals (or regular distances) in a circumferential direction inside the drum. The second length L2 of the second portion may be smaller than a radius of the drum. The first angle θ1 between the drum and the second portion may be 90 degrees or more. The plurality of electrodes 90 may be spaced apart along an outer circumference of the drum. The clothes dryer may further include a DC power supply configured to provide DC power to the RF power supply. The lifter may be fixed to the drum by at least one of adhesion, welding, or screws. The plurality of lifters may include the second gap G2 between adjacent lifters, and the second portion may cover the second gap G2 as the first angle θ1 increases.

[0138] With such lifters, the capacitance variation according to the rotation of the object inside the drum may be reduced.

[0139] The clothes dryer may further include a controller configured to control the RF power supply, wherein the controller may adjust a speed (rpm) of the drum to compensate for an increase in a friction coefficient of an inner wall of the drum according to the number of the lifters. The controller may compensate for the increase in the friction coefficient of the inner wall of the drum caused by the lifter by adjusting a rotational direction of the drum in a direction opposite to a bending direction of the second portion. By orienting the bending direction of the second portion of the lifter in a direction opposite to the rotational direction of the drum, a surface friction coefficient of the object to be dried inside the drum may be reduced.

[0140] The clothes dryer according to an embodiment may include: a cabinet; a drum rotatably provided inside the cabinet; a plurality of electrodes 90, which are spaced apart along an outer circumference of the drum between the cabinet and the drum; an RF power supply configured to apply a voltage to the plurality of electrodes 90 to generate an electric field for dielectric heating of an object to be dried accommodated in the drum; a DC power supply configured to provide DC power to the RF power supply; and a lifter rotatably provided with the drum inside the drum, the lifter including a floating metal lifter that is not electrically connected. According to the disclosure, the lifter may reduce the capacitance variation according to rotation of the object to be dried inside the drum. For example, the efficiency of the clothes dryer may be increased by increasing the capacitance of the electrodes 90.

[0141] The lifter may include a first portion in contact with the drum, and a second portion bent from the first portion and facing an inner side of the drum. The plurality of electrodes 90 may include the first gap G1 between adjacent electrodes 90, and the first length L1 of the first portion may be shorter than the first gap G1. A plurality of lifters may be provided and be disposed at regular intervals (or regular distances) in a circumferential direction inside the drum. The second length L2 of the second portion may be smaller than a radius of the drum. The first angle θ1 between the drum and the second portion may be 90 degrees or more. The plurality of lifters may have the second gap G2 between adjacent lifters, and the second portion may cover the second gap G2 as the first angle θ1 increases. With such lifters, the capacitance variation according to the rotation of the object to be dried inside the drum may be reduced. The rate of capacitance variation of the electrodes 90 according to the rotation of the lifter caused by the tumble behavior of the drum may be minimized.

[0142] The clothes dryer may further include a controller configured to control the RF power supply, and the controller may determine a rotational speed of the drum.

[0143] According to an embodiment, the object to be dried may be uniformly dried through dielectric heating.

[0144] According to an embodiment, the capacitance of the electrode (e.g., external electrode) disposed in a circumferential direction outside the drum may be increased.

[0145] According to an embodiment, the capacitance variation according to the rotation of the object to be dried inside the drum may be reduced.

[0146] According to an embodiment, the capacitance may be improved through the lifter inside the drum.

[0147] According to an embodiment, the efficiency of the clothes dryer may be increased by increasing the capacitance of the electrodes.

[0148] According to an embodiment, during the tumble operation of the object to be dried having a dielectric constant, the rate of capacitance variation of the external electrode may be reduced, and the rate of load variation may be reduced.

[0149] The effects to be obtained from the disclosure are not limited to those mentioned above, and other effects not mentioned will be apparent to a person skilled in the art to which the disclosure belongs from the following description.

[0150] Although specific embodiments have been illustrated and described above, the disclosure is not limited to the embodiments described above, and it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the gist of the technical spirit of the invention described in the claims below.

Claims

1. A clothes dryer comprising:a cabinet;a drum configured to rotate in the cabinet;a plurality of electrodes between the cabinet and the drum;a radio frequency (RF) power supply configured to apply a voltage to the plurality of electrodes to generate an electric field for dielectric heating of an object accommodated in the drum; andat least one lifter provided in the drum, formed of a metal material, electrically floated, and configured to rotate with the drum, each of the at least one lifter comprising a first portion in contact with the drum and a second portion bent from the first portion and facing an inner side of the drum.

2. The clothes dryer of claim 1, wherein adjacent electrodes of the plurality of electrodes are separated by a first gap, andwherein a first length of the first portion is shorter than the first gap.

3. The clothes dryer of claim 2, wherein the at least one lifter comprises a plurality of lifters, andwherein the first gap is overlapped by one or more of the plurality of lifters.

4. The clothes dryer of claim 3, wherein the plurality of lifters are at regular intervals in a circumferential direction inside the drum.

5. The clothes dryer of claim 3, wherein a second length of the second portion is smaller than a radius of the drum.

6. The clothes dryer of claim 5, wherein a first angle between the drum and the second portion is at least 90 degrees.

7. The clothes dryer of claim 1, wherein the plurality of electrodes are spaced apart along an outer circumference of the drum.

8. The clothes dryer of claim 1, further comprising:a direct current (DC) power supply configured to provide DC power to the RF power supply.

9. The clothes dryer of claim 1, wherein the at least one lifter is fixed to the drum by at least one of adhesion, welding, or screws.

10. The clothes dryer of claim 6, wherein adjacent lifters of the plurality of lifters are separated by a second gap, andwherein the second portion covers the second gap as the first angle increases.

11. The clothes dryer of claim 1, further comprising a controller configured to control the RF power supply,wherein the at least one lifter comprises a plurality of lifters, andwherein the controller is further configured to adjust a speed of the drum to compensate for an increase in a friction coefficient of an inner wall of the drum according to a number of the plurality of lifters.

12. The clothes dryer of claim 11, wherein the controller is further configured to compensate for the increase in the friction coefficient of the inner wall of the drum by adjusting a rotational direction of the drum in a direction opposite to a bending direction of the second portion.

13. A clothes dryer comprising:a cabinet;a drum configured to rotate in the cabinet;a plurality of electrodes spaced apart along an outer circumference of the drum between the cabinet and the drum;a radio frequency (RF) power supply configured to apply a voltage to the plurality of electrodes to generate an electric field for dielectric heating of an object accommodated in the drum;a direct current (DC) power supply configured to provide DC power to the RF power supply; andat least one lifter in the drum and configured to rotate with drum, the at least one lifter being electrically floated and being formed of metal without electrical connection.

14. The clothes dryer of claim 13, wherein each of the at least one lifter comprises:a first portion in contact with the drum, and a second portion bent from the first portion and facing an inner side of the drum.

15. The clothes dryer of claim 14, wherein the at least one lifter comprises a plurality of lifters at regular intervals in a circumferential direction inside the drum.

16. The clothes dryer of claim 15, wherein adjacent electrodes of the plurality of electrodes are separated by a first gap, and a first length of the first portion is shorter than the first gap.

17. The clothes dryer of claim 16, wherein a second length of the second portion is smaller than a radius of the drum.

18. The clothes dryer of claim 17, wherein a first angle between the drum and the second portion is at least 90 degrees.

19. The clothes dryer of claim 18, wherein adjacent lifters of the plurality of lifters are separated by a second gap, andwherein the second portion covers the second gap as the first angle increases.

20. The clothes dryer of claim 13, further comprising a controller configured to control the RF power supply, and determine a rotational speed of the drum.

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