Dryer and method for controlling same

Abstract

The disclosed dryer comprises: a chamber; a first electrode disposed at a first side of the chamber; a second electrode disposed at a second side of the chamber facing the first side; an RF power supply unit operated by an AC voltage input from an AC power source and applying an RF signal to the first electrode and the second electrode; an impedance matching circuit that performs impedance matching between the RF power supply unit and the first and second electrodes; and a frequency control circuit that adjusts the frequency of a switching signal for turning on or off the RF power supply unit, on the basis of a change in magnitude of the AC voltage.

Description

Dryer and control method thereof

[0001] The disclosed invention relates to a dryer capable of drying an object through dielectric heating and a method for controlling the same.

[0002] A dryer is a device capable of drying objects (e.g., clothing) by removing moisture contained within them. Various types of drying devices exist that can dry objects. For example, there are dryers that supply hot air into a drum containing the object to dry it. In the case of this method, heat is transferred from air, which has a low specific heat, to water, which has a high specific heat; consequently, the heat transfer efficiency is low, and the drying efficiency is consequently low. Furthermore, the high-temperature air supplied into the drum can damage the object.

[0003] As another example, there are dryers capable of drying objects through dielectric heating using RF (Radio Frequency). Conventional dryers utilizing dielectric heating place an object between two parallel flat electrodes and heat the water contained in the object by generating an electric field between the two electrodes. However, conventional dryers only generate an electric field of constant strength between the two electrodes and cannot adjust the strength of the electric field to reflect the impedance that changes as the object dries.

[0004] The disclosed invention provides a dryer and a control method capable of driving an RF power supply unit using alternating current power supplied from an alternating current power source.

[0005] The disclosed invention provides a dryer and a control method capable of minimizing and / or reducing high-frequency noise by adjusting the switching frequency for controlling an RF power supply according to the magnitude of the AC voltage.

[0006] A dryer according to one embodiment may include: a chamber; a first electrode disposed on a first side of the chamber; a second electrode disposed on a second side of the chamber facing the first side; an RF power supply unit that operates by an alternating current voltage input from an alternating current power source and applies an RF signal to the first electrode and the second electrode; an impedance matching circuit that performs impedance matching between the first electrode and the second electrode and the RF power supply unit; and a frequency control circuit that adjusts the frequency of a switching signal to turn the RF power supply unit on or off based on a change in the magnitude of the alternating current voltage.

[0007] A control method for a dryer comprising an RF power supply unit that operates by an AC voltage input from an AC power source and applies an RF signal to a first electrode and a second electrode, and an impedance matching circuit that performs impedance matching between the first electrode and the second electrode and the RF power supply unit, wherein the control method according to one embodiment may include: identifying a change in the magnitude of the AC voltage by means of a frequency control circuit; and adjusting the frequency of a switching signal for turning the RF power supply unit on or off based on the change in the magnitude of the AC voltage by means of the frequency control circuit.

[0008] The disclosed dryer and control method can drive an RF power supply unit using AC power supplied from an AC power source. The disclosed dryer and control method may not require a circuit structure and control process for driving an RF power supply unit using DC power. Therefore, compared to the prior art, the types of circuits included in the dryer, the size of the circuits, and the manufacturing costs of the circuits are reduced, and the circuit control method can be simplified.

[0009] The disclosed dryer and control method can minimize and / or reduce high-frequency noise by adjusting the switching frequency for controlling the RF power supply according to the magnitude of the AC voltage.

[0010] In addition, the disclosed dryer and control method enable adaptive impedance matching by adjusting the switching frequency corresponding to the AC voltage, and can adaptively respond to changes in load impedance due to the movement of the object to be dried and the progress of drying.

[0011] Figure 1 illustrates a network system implemented by various electronic devices.

[0012] FIG. 2 illustrates a dryer according to one embodiment.

[0013] FIG. 3 is a cross-sectional view of a dryer according to one embodiment.

[0014] FIG. 4 illustrates the arrangement structure of electrodes according to one embodiment.

[0015] FIG. 5 is a control block diagram of a dryer according to one embodiment.

[0016] FIG. 6 illustrates a circuit system for a drying operation of a dryer according to one embodiment.

[0017] Figures 7 and 8 illustrate the detailed circuit structure of the circuit system shown in Figure 6.

[0018] Figure 9 is a graph briefly illustrating the relationship between the change in the magnitude of the AC voltage and the frequency of the switching signal for turning the RF power supply on or off.

[0019] Figure 10 is a graph showing the switching signal applied to the RF power supply according to the change in the magnitude of the AC voltage.

[0020] Figure 11 is a graph illustrating the operation of a frequency control circuit that determines the frequency of a switching signal applied to an RF power supply according to changes in the magnitude of the AC voltage.

[0021] FIG. 12 is a flowchart illustrating a control method for a dryer according to one embodiment.

[0022] Figure 13 is a flowchart that explains in more detail the control method of the dryer described in Figure 12.

[0023] The various embodiments of this document and the terms used therein are not intended to limit the technical features described in this document to specific embodiments, and should be understood to include various modifications, equivalents, or substitutions of said embodiments.

[0024] In relation to the description of the drawings, similar reference numerals may be used for similar or related components.

[0025] The singular form of the noun corresponding to an item may include one or plural items, unless the relevant context clearly indicates otherwise.

[0026] In this document, each of the 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 of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0027] Terms such as "first," "second," or "first" or "second" may be used simply to distinguish a component from another component and do not limit the components in other aspects (e.g., importance or order).

[0028] Where any (e.g., 1st) component is referred to as "coupled" or "connected" to another (e.g., 2nd) component, with or without the terms "functionally" or "communicationly," it means that the component may be connected to the other component directly (e.g., via a wire), wirelessly, or through a third component.

[0029] Terms such as “include” or “have” are intended to specify the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in this document, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0030] When it is said that a component is "connected," "combined," "supported," or "in contact" with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.

[0031] When it is said that a component is located "on" another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.

[0032] The term “and / or” includes a combination of multiple related described components or any of the multiple related described components.

[0033] The operating principle and embodiments of the present invention will be described below with reference to the attached drawings.

[0034] Figure 1 illustrates a network system implemented by various electronic devices.

[0035] Referring to FIG. 1, the home appliance (10) may include a communication module capable of communicating with another home appliance, a user device (2) or a server (3), a user interface that receives user input or outputs information to the user, at least one processor that controls the operation of the home appliance (10), and at least one memory in which a program for controlling the operation of the home appliance (10) is stored.

[0036] The home appliance (10) may be at least one of various types of home appliances. For example, the home appliance (10) may include at least one of a refrigerator (11), a dishwasher (12), an electric range (13), an electric oven (14), an air conditioner (15), a garment care machine (16), a washing machine (17), a dryer (18), and a microwave oven (19), as illustrated.

[0037] The home appliance (10) is not limited to that exemplified in FIG. 1. For example, the home appliance (10) may include various home appliances such as a cleaning robot, a vacuum cleaner, and a television that are not illustrated in the drawing. In addition, the aforementioned home appliances are merely examples, and in addition to the aforementioned home appliances, other home appliances, user devices (2), or devices that can be connected to a server (3) to perform the operations described below may be included in the home appliance (10) according to one embodiment.

[0038] The server (3) may include a communication module (including a communication circuit) capable of communicating with another server, home appliance (10), or user device (2), at least one processor capable of processing data received from another server, home appliance (10), or user device (2), and at least one memory capable of storing a program for processing data or processed data. This server (3) may be implemented as various computing devices such as a workstation, cloud, data drive, or data station. The server (3) may be implemented as one or more servers physically or logically separated based on functions, detailed configurations of functions, or data, and may transmit and receive data and process the transmitted and received data through communication between each server.

[0039] The server (3) can perform functions such as managing user accounts, registering home appliances (10) associated with user accounts, and managing or controlling the registered home appliances (10). For example, a user can create a user account by accessing the server (3) through a user device (2). A user account can be identified by an ID and password set by the user. The server (3) can register home appliances (10) to the user account according to a set procedure. For example, the server (3) can register, manage, and control home appliances (10) by linking identification information of the home appliance (10) (e.g., serial number or MAC address, etc.) to the user account. The user device (2) may include a communication module capable of communicating with the home appliance (10) or the server (3), a user interface that receives user input or outputs information to the user, at least one processor that controls the operation of the user device (2), and at least one memory in which a program for controlling the operation of the user device (2) is stored.

[0040] The user device (2) may be carried by the user or placed in the user's home or office, etc. The user device (2) may include, but is not limited to, a personal computer, terminal, portable telephone, smartphone, handheld device, wearable device, etc.

[0041] A program, i.e., an application, for controlling the home appliance (10) can be stored in the memory of the user device (2). The application may be sold with the user device (2) already installed, or it may be downloaded and installed from an external server.

[0042] By running an application installed on the user device (2), the user can connect to the server (3) to create a user account, and communicate with the server (3) based on the logged-in user account to register the home appliance device (10).

[0043] For example, if the home appliance (10) is operated in accordance with the procedure guided by the application installed on the user device (2) so that the home appliance (10) can be connected to the server (3), the home appliance (10) can be registered to the user account by registering the identification information of the home appliance (10) (e.g., serial number or MAC address, etc.) to the user account on the server (3).

[0044] The user can control the home appliance (10) using an application installed on the user device (2). For example, when the user logs into the user account using an application installed on the user device (2), the home appliance (10) registered to the user account appears, and when the user inputs a control command for the home appliance (10), the control command can be transmitted to the home appliance (10) through the server (3).

[0045] A network may include both wired and wireless networks. Wired networks include cable networks or telephone networks, etc., and wireless networks may include all networks that transmit and receive signals via radio waves. Wired and wireless networks may be connected to each other.

[0046] The network may include a wide area network (WAN) such as the Internet, a local area network (LAN) formed around an access point (AP), and / or a short-range wireless network that does not pass through an access point (AP). The short-range wireless network may include, for example, Bluetooth (IEEE 802.15.1), Zigbee (IEEE 802.15.4), Wi-Fi Direct, Near Field Communication (NFC), Z-Wave, etc., but is not limited to those exemplified.

[0047] The access point (AP) can connect a home appliance (10) or a user device (2) to a wide area network (WAN) to which a server (3) is connected. The home appliance (10) or the user device (2) can be connected to the server (3) through the wide area network (WAN).

[0048] The access point (AP) can communicate with a home appliance (10) or user device (2) using wireless communication such as Wi-Fi (IEEE 802.11), Bluetooth (IEEE 802.15.1), or Zigbee (IEEE 802.15.4), and can connect to a wide area network (WAN) using wired communication, but is not limited thereto.

[0049] According to various embodiments, the home appliance (10) may be directly connected to the user device (2) or server (3) without going through the access relay (AP).

[0050] The home appliance (10) can be connected to a user device (2) or server (3) via a long-distance wireless network or a short-distance wireless network.

[0051] For example, the home appliance (10) can be connected to the user device (2) via a short-range wireless network (e.g., Wi-Fi Direct).

[0052] As another example, the home appliance (10) can be connected to a user device (2) or server (3) via a wide area network (WAN) using a long-distance wireless network (e.g., a cellular communication module).

[0053] As another example, a home appliance (10) can be connected to a wide area network (WAN) using wired communication and can be connected to a user device (2) or a server (3) through the wide area network (WAN).

[0054] If the home appliance (10) can connect to a wide area network (WAN) using wired communication, it may operate as a connection relay. Accordingly, the home appliance (10) can connect other home appliances to the wide area network (WAN) to which the server (3) is connected. Additionally, other home appliances can connect the home appliance (10) to the wide area network (WAN) to which the server (3) is connected.

[0055] The home appliance (10) can transmit information regarding operation or status to other home appliances, user devices (2), or servers (3) via a network. For example, the home appliance (10) can transmit information regarding operation or status to other home appliances, user devices (2), or servers (3) when a request is received from the server (3), when a specific event occurs in the home appliance (10), or periodically or in real time. When the server (3) receives information regarding operation or status from the home appliance (10), it can update the stored information regarding operation or status of the home appliance (10) and transmit the updated information regarding operation and status of the home appliance (10) to the user devices (2) via a network. Here, updating information may include various operations that change existing information, such as adding new information to existing information or replacing existing information with new information.

[0056] The home appliance (10) can obtain various information from other home appliances, user devices (2), or servers (3) and provide the obtained information to the user. For example, the home appliance (10) can obtain information related to the functions of the home appliance (10) (e.g., recipes, laundry methods, etc.) and various environmental information (e.g., weather, temperature, humidity, etc.) from the server (3), and can output the obtained information through a user interface.

[0057] The home appliance (10) may operate according to control commands received from other home appliances, user devices (2), or servers (3). For example, if the home appliance (10) has obtained prior approval from a user to operate according to control commands from servers (3) even without user input, the home appliance (10) may operate according to control commands received from servers (3). Here, the control commands received from servers (3) may include, but are not limited to, control commands entered by the user through user devices (2) or control commands based on pre-set conditions.

[0058] The user device (2) can transmit information about the user to the home appliance (10) or server (3) through a communication module. For example, the user device (2) can transmit information about the user's location, health status, preferences, schedule, etc. to the server (3). The user device (2) can transmit information about the user to the server (3) upon the user's prior approval.

[0059] The home appliance (10), user device (2), or server (3) may determine control commands using technology such as artificial intelligence. For example, the server (3) may receive information regarding the operation or status of the home appliance (10) or information regarding the user of the user device (2), process it using technology such as artificial intelligence, and transmit the processing result or control command to the home appliance (10) or user device (2) based on the processing result.

[0060] The dryer (1) described below may correspond to the aforementioned home appliance (10).

[0061] FIG. 2 illustrates a dryer according to one embodiment.

[0062] Referring to FIG. 2, the dryer (1) may include a cabinet (1a) forming an exterior and a drum (20) rotatably installed within the cabinet (1a). The internal space of the drum (20) may form a chamber (20a) for receiving an object.

[0063] The cabinet (1a) may be provided in a roughly cuboidal shape. The cabinet (1a) may include a top cover (1b) forming the top surface, a front cover (1c) forming the front surface, and a base forming the bottom surface. For example, the front cover (1c), top cover (1b), and base forming the cabinet (1a) may each be provided separately and assembled. As another example, some components forming the cabinet (1a) (e.g., front cover, top cover, base) may be formed integrally.

[0064] An input port (31) is provided on the front of the cabinet (1a) for inserting or withdrawing an object, such as clothing (not shown), into or out of the drum (20). The dryer (1) may include a door (50) provided to open and close the input port (31) formed in the front cover (1c). After opening the door (50), the user can insert or discharge an object into or out of the drum (20) through the input port (31). When the input port (31) is closed and the dryer (1) starts operating, a door lock can lock the door (50).

[0065] A user interface (100) for interaction between the user and the dryer (1) may be provided on the upper front side of the cabinet (1a). The user interface (100) can receive user input and display various information regarding the dryer (1). The location of the user interface (100) is not limited to the front. The user interface (100) may be provided at various locations on the dryer (1).

[0066] The user interface (100) may include a display. Additionally, the user interface (100) may include an input section for obtaining user input regarding the operation of the dryer (1). The input section may include a rotatable dial and various buttons. Furthermore, the user interface (100) may include various types of input sections and displays.

[0067] The display may be provided as various types of display panels. For example, the display may include a Liquid Crystal Display Panel (LCD Panel), a Light Emitting Diode Panel (LED Panel), an Organic Light Emitting Diode Panel (OLED Panel), or a Micro LED Panel. The display may also be used as an input device, including a touch screen.

[0068] The display can display information entered by the user or information provided to the user on various screens. The display can display information related to the operation of the dryer (1) as at least one of an image or text. In addition, the display can display a graphic user interface (GUI) that enables control of the dryer (1). That is, the display can display UI elements such as icons.

[0069] The input unit can transmit an electrical signal (voltage or current) corresponding to user input to the control unit (300). The input unit may include various buttons and / or a dial. For example, the input unit may include at least one of a power button for turning the power of the dryer (1) on or off, a start / stop button for starting or stopping the drying operation, a drying mode button for selecting a drying mode, a temperature button for setting the drying temperature, and a time button for setting the drying time. The various buttons may be provided as physical buttons or touch buttons.

[0070] A dial included in the input section may be rotatably provided. UI elements displayed on the display may move sequentially depending on the rotation of the dial. The dryer (1) may perform drying according to a selected drying mode. The drying mode may include drying parameters such as drying temperature and drying time. Different drying modes may be selected depending on the position of the object within the drum (20), the type of object, and / or the amount of object.

[0071] The dryer (1) may include a filter (40) that is detachably mounted on the front cover (1c). The filter (40) can filter out foreign substances, such as lint, that flow with the air circulating inside the drum (20).

[0072] FIG. 3 is a cross-sectional view of a dryer according to one embodiment.

[0073] Referring to FIG. 3, a cylindrical drum (20) may be provided inside the cabinet (1a). An object may be accommodated in the internal space of the drum (20). The drum (20) may be provided to be rotatable by receiving power from a motor (72). The drum (20) may be provided inside the cabinet (1a) so as to be rotatable around a rotating axis that is approximately horizontal to the ground.

[0074] A lifter (21) may be provided on the inner surface of the drum (20) so that an object can be lifted when the drum (20) rotates. Depending on the rotational speed of the drum (20), the object may repeatedly rise and fall by the lifter (21). A roller (22) may be provided on the outer surface of the drum to support the drum (20) so that it rotates smoothly.

[0075] The drive unit may be positioned in the inner lower part of the cabinet (1a). The drive unit may be mounted on a base. The drive unit may include a motor (72), a pulley (74) and a belt (75) for transmitting power from the motor (72) to the drum (20).

[0076] The pulley (74) can be connected to a rotating shaft (73) connected to a motor (72). When the rotating shaft (73) is rotated by the motor (72), the pulley (74) can rotate together with the rotating shaft (73). A belt (75) can be installed to be wound around the outer surface of the pulley (74) and the outer surface of the drum (20). When the belt (75) is rotated by the driving force of the motor (72), the drum (20) can rotate together with the belt (75). The drum (20) can rotate clockwise or counterclockwise.

[0077] A passage (80) for circulating air may be formed inside the cabinet (1a) and inside the drum (20). The passage (80) may include an air discharge passage (81) for discharging air from inside the drum (20) to outside the drum (20), and an air supply passage (82) for supplying air into the drum (20).

[0078] The dryer (1) may include an exhaust duct (60) that forms an air exhaust passage (81). A filter (40) may be placed at the inlet (61) of the exhaust duct (60). The exhaust duct (60) may pass through the cabinet (1a), and the outlet (63) of the exhaust duct (60) may be exposed to the outside of the cabinet (1a). Air entering through the inlet (61) of the exhaust duct (60) may be filtered as it passes through the filter (40). The filter (40) may filter out foreign substances, such as lint, contained in the air.

[0079] A fan (71) for circulating air may be provided inside the cabinet (1a). By the rotation of the fan (71), air inside the drum (20) may be drawn into the exhaust duct (60). Additionally, depending on the rotation of the fan (71), air may be supplied into the drum (20) through the air supply passage (83) and the air inlet (20b) of the drum (20). The air supplied into the drum (20) may be used for drying an object.

[0080] The motor (72) can rotate not only the drum (20) but also the fan (71). Although the drum (20) and the fan (71) are exemplified as being driven by a single motor (72), this is not limited thereto. A separate fan motor (not shown) may be provided for driving the fan (71). Additionally, the motor (72) may be directly connected to the drum (20) to rotate the drum (20). When the motor (72) is directly connected to the drum (20), the pulley (74) and belt (75) may be omitted.

[0081] A plurality of electrodes (90) may be provided between the cabinet (1a) and the drum (20). For example, a first electrode (90a) and a second electrode (90b) may be provided between the cabinet (1a) and the drum (20). The first electrode (90a) and the second electrode (90b) may be spaced apart from each other along the circumference of the drum (20). Two or more first electrodes (90a) and second electrodes (90b) may be provided for each. The first electrode (90a) and the second electrode (90b) may be spaced apart from the cabinet (1a) and the drum (20).

[0082] The dryer (1) is exemplified as a drum dryer but is not limited thereto. The dryer (1) may be provided in a form having a storage space formed by shelves. The dryer (1) may not include a drum (20), in which case the position of the object placed between the first electrode (90a) and the second electrode (90b) may not change.

[0083] FIG. 4 illustrates the arrangement structure of electrodes according to one embodiment.

[0084] Referring to FIG. 4, a plurality of electrodes (90) may be arranged along the circumference of a drum (20). The plurality of electrodes (90) may be spaced apart from each other. In the case of a dryer (1) including a drum (20), each of the plurality of electrodes (90) may be provided in a plate shape having curvature. In the case of a dryer (1) not including a drum (20), each of the plurality of electrodes (90) may be provided in a flat plate shape.

[0085] A plurality of electrodes (90) may include a first electrode (90a) and a second electrode (90b). The first electrode (90a) and the second electrode (90b) may be spaced apart along the outer surface of the drum (20).

[0086] A plurality of electrodes (90) can be fixed between the cabinet (1a) and the drum (20). The drum (20) is not connected to the electrodes (90). Therefore, the electrodes (90) do not restrict the rotation of the drum (20). Additionally, since the plurality of electrodes (90) are arranged along the circumference of the drum (20), an electric field can be generated within the drum (20). Thus, the disclosed dryer (1) can generate an electric field inside the drum (20) through the electrodes (90) even while the drum (20) is rotating, and can perform drying of the object.

[0087] The number of electrodes (90) is exemplified as two, but is not limited thereto. The dryer (1) may include two or more electrodes (90).

[0088] The disclosed dryer (1) includes a circuit structure capable of supplying power suitable for drying an object. When power is supplied to the electrode (90), an electric field can be generated in the chamber (20a). The electric field generated inside the drum (20) by the electrode (90) can cause a dielectric (e.g., water molecules) contained in the object to vibrate. When the dielectric (e.g., water molecules) vibrates, dipole frictional heat is generated, and the dielectric can be heated. The object can be dried as the heated dielectric evaporates. The evaporated dielectric can be discharged outside the drum (20) along with the air supplied into the drum (20).

[0089] FIG. 5 is a control block diagram of a dryer according to one embodiment.

[0090] Referring to FIG. 5, the dryer (1) may include a circuit system for performing a drying operation. For example, the dryer (1) may include a rectifier circuit (110), an RF power supply (120), a frequency control circuit (130), an impedance matching circuit (140), and an electrode (90). The dryer (1) may include a motor (72) that rotates a drum (20) and a fan (71), a user interface (e.g., including circuit) (100), and a communication interface (e.g., including communication circuit) (200). Additionally, the dryer (1) may include a control unit (e.g., including circuit) (300) that is electrically connected to and controls various electronic components.

[0091] The user interface (100) includes various circuits, can acquire user input, and can display various information regarding the operation of the dryer (1). The user interface (100) may include an input unit for acquiring user input and a display for displaying information. Additionally, the user interface (100) may include a speaker for outputting sound.

[0092] The user interface (100) can display operation information of the dryer (1). For example, the user interface (100) can display a drying mode, a drying temperature, an estimated drying time, and / or the time remaining until the end of drying. The drying mode may include predetermined drying settings (e.g., degree of drying, additional time for wrinkle prevention, drying time) depending on the type of object (e.g., shirt, duvet, underwear) and material (e.g., cotton, wool). For example, standard drying may include drying settings applicable to most objects, and duvet drying may include drying settings optimized for drying duvets.

[0093] The communication interface (200) includes various communication circuits and can perform a connection with at least one of a user device (2) or a server (3) through a network. The control unit (300) can obtain various information, various signals and / or various data from the user device (2) or the server (3) through the communication interface (200). For example, the communication interface (200) can receive a remote control signal from the user device (2). The control unit (300) can obtain firmware and / or software for the operation of the dryer (1) from the server (3) through the communication interface (200).

[0094] The communication interface (200) may include various communication circuits. The communication interface (200) may include wireless communication circuits and / or wired communication circuits. For example, a communication circuit supporting wireless communication methods such as wireless local area network (LAN), home radio frequency (RF), infrared communication, ultra-wide band (UWB) communication, Wi-Fi, Bluetooth, and Zigbee may be provided.

[0095] The control unit (300) includes various circuits and can be electrically connected to the components of the dryer (1) and can control the components of the dryer (1). For example, the control unit (300) can control the motor (72) to rotate the drum (20) and the fan (71). The control unit (300) can control the RF power supply unit (120), the frequency control circuit (130), and the impedance matching circuit (140) to supply power to the electrode (90). The control unit (300) can control the RF power supply unit (120), the frequency control circuit (130), and the impedance matching circuit (140) to improve drying efficiency while performing the drying operation of the object.

[0096] The control unit (300) may include a processor (e.g., including a processing circuit) (310) and a memory (320). The memory (320) may include volatile memory (e.g., S-RAM, D-RAM) and non-volatile memory (e.g., ROM, EEPROM). The processor (310) and the memory (320) may be implemented as separate chips or as a single chip. Additionally, multiple processors and multiple memories may be provided.

[0097] The processor (310) includes various processing circuits and can process various data and various signals using instructions, data, programs and / or software stored in memory (320). The processor (310) can generate control signals for controlling the components of the dryer (1). The processor (310) may include one core or multiple cores.

[0098] The processor (310) may be configured to perform various operations of the dryer (1). The processor (310) may perform operations of the dryer (1) according to various embodiments by executing at least one instruction, algorithm, program and / or software stored in memory (320). The processor (310) may control one or any combination of the components of the dryer (1).

[0099] The processor (310) may include various types of circuits. For example, the processor (310) may include one or more of a CPU (Central Processing Unit), GPU (Graphics Processing Unit), APU (Accelerated Processing Unit), MIC (Many Integrated Core), DSP (Digital Signal Processor), NPU (Neural Processing Unit), hardware accelerator, or machine learning accelerator. Accordingly, the processor (310) may include various processing circuits and / or multiple processors. For example, as used in this specification including the claims, the term “processor” may include various processing circuits including at least one processor, wherein at least one of the at least one processor may be configured to perform various functions described in this specification individually and / or collectively in a distributed manner. As used herein, when "processor," "at least one processor," and "one or more processors" are described as being configured to perform a plurality of functions, these terms encompass, for example and without limitation, situations in which one processor performs some of the mentioned functions and other processor(s) perform other of the mentioned functions, and also situations in which a single processor can perform all of the mentioned functions. Additionally, the at least one processor may include a combination of processors performing various of the mentioned / disclosed functions, for example, in a distributed manner. The at least one processor may execute program instructions to achieve or perform various functions.

[0100] The rectifier circuit (110) is connected to a commercial power source (AC) and can rectify AC power supplied from the commercial power source (AC). For example, the rectifier circuit (110) can convert a negative voltage of AC voltage into a positive voltage. The rectifier circuit (110) may include a full-wave rectifier circuit or a half-wave rectifier circuit. The AC voltage rectified by the rectifier circuit (110) can be input to an RF power supply unit (120).

[0101] The RF power supply unit (120) can operate by an alternating voltage input from an alternating current power source (AC). The RF power supply unit (120) can generate an RF signal and apply the RF signal to the electrode (90). Sinusoidal power can be applied to the electrode (90) by the RF signal. The control unit (300) can control the RF power supply unit (120) to adjust the RF power applied to the electrode (90). When RF power is supplied to the electrode (90), an electric field for dielectric heating of the object can be generated within the drum (20). The phase of the RF power applied to each of the plurality of electrodes (90) may be different. As RF power having different phases is applied to the plurality of electrodes (90), an electric field can be generated within the drum (20).

[0102] The frequency control circuit (130) can adjust the frequency of a switching signal to turn the RF power supply (120) on or off based on a change in the magnitude of the AC voltage. The frequency of the switching signal may also be referred to as the 'switching frequency'. The frequency control circuit (130) can be electrically connected to the control unit (300) and can adjust the switching frequency to control the operation of the RF power supply (120) according to the control of the control unit (300). For example, the frequency control circuit (130) can determine the frequency of the switching signal to control the operation of the RF power supply (120) to be smaller as the magnitude of the AC voltage increases. The magnitude of the AC voltage may represent an instantaneous value.

[0103] The frequency control circuit (130) can divide the magnitude of the AC voltage that changes over time into multiple intervals. The frequency control circuit (130) can determine a different switching frequency for controlling the operation of the RF power supply unit (120) for each of the multiple intervals. The control unit (300) can divide the magnitude of the AC voltage into multiple intervals and set multiple threshold values ​​to determine the switching frequency corresponding to each interval. The frequency control circuit (130) can determine the switching frequency of the RF power supply unit (120) by comparing the magnitude of the AC voltage with multiple threshold values.

[0104] For example, the frequency control circuit (130) can determine the frequency of the switching signal as a reference frequency if the magnitude of the AC voltage is smaller than a first threshold value. The frequency control circuit (130) can determine the frequency of the switching signal as a first frequency lower than the reference frequency if the magnitude of the AC voltage is greater than or equal to the first threshold value and smaller than a second threshold value. The second threshold value can be set to be greater than the first threshold value. The frequency control circuit (130) can determine the frequency of the switching signal as a second frequency lower than the first frequency if the magnitude of the AC voltage is greater than or equal to the second threshold value.

[0105] Although it has been exemplified that the switching frequency of the RF power supply unit (120) is adjusted by dividing the magnitude of the AC voltage input to the RF power supply unit (120) into three sections, it is not limited thereto. The magnitude of the AC voltage may be divided into three or more sections.

[0106] Conventional dryers required many power conversion circuits to convert the input voltage of the RF power supply unit (120) into a DC voltage. For example, conventional dryers required an EMI filter to remove noise included in the AC power, a power factor compensation circuit to compensate the power factor of the AC power, and a DCDC converter to convert the power output from the power factor compensation circuit into DC power suitable for the RF power supply unit (120). In conventional dryers, the RMS value of the AC voltage supplied from the AC power source was used as the input voltage of the RF power supply unit (120). In the prior art, because a continuously high voltage and / or power was applied to the RF power supply unit (120), high-frequency noise was continuously generated.

[0107] However, the disclosed dryer (1) may not require a circuit structure and control process for driving the RF power supply unit (120) using DC power. For example, the dryer (1) may not include an EMI filter, a power factor compensation circuit, and a DCDC converter. Therefore, compared to the prior art, the type of circuit included in the dryer (1), the size of the circuit, and the manufacturing cost of the circuit are reduced, and the method of controlling the circuit can be simplified.

[0108] The disclosed dryer (1) can minimize and / or reduce high-frequency noise by driving the RF power supply unit (120) using an alternating voltage and adjusting the switching frequency for controlling the RF power supply unit (120) according to the magnitude of the alternating voltage.

[0109] An impedance matching circuit (140) may be provided between an RF power supply unit (120) and a plurality of electrodes (90). An RF signal generated by the RF power supply unit (120) may be transmitted to the electrodes (90) through the impedance matching circuit (140).

[0110] The impedance matching circuit (140) can match the output impedance of the RF power supply unit (120) with the electrode impedance of the electrode (90). If there is a difference between the output impedance of the RF power supply unit (120) and the electrode impedance of the electrode (90), reflected power is generated from the electrode (90), and the power transmission efficiency is reduced. To minimize reflected power, it is necessary to perform matching between the output impedance of the RF power supply unit (120) and the electrode impedance of the electrode (90). The control unit (300) can perform impedance matching by controlling the impedance matching circuit (140).

[0111] The electrode impedance of the electrode (90) can vary depending on various factors such as the amount of object contained in the drum (20), the type of object, the size of the object, the amount of water contained in the object, and the distribution state of the object. For example, if a dielectric with a high permittivity (e.g., water) is present between the two electrodes (90), the strength of the electric field formed between the two electrodes (90) may decrease because charge accumulates in the dielectric. As the strength of the electric field decreases, the magnitude of the output voltage of the electrode (90) may decrease, and the electrode impedance may decrease. As the drying of the object proceeds, the water contained in the object is removed, so the electrode impedance may be detected to gradually increase.

[0112] As the drying of the object progresses, the rate of change in the impedance of the object may decrease. The control unit (300) can determine the degree of drying of the object based on the rate of change in the impedance of the object. The control unit (300) can determine the completion of drying based on the degree of drying of the object reaching within the allowable tolerance range of a predetermined standard degree of drying. Additionally, the control unit (300) can determine the completion of drying when the impedance value of the object becomes greater than or equal to a predetermined threshold value.

[0113] FIG. 6 illustrates a circuit system for a drying operation of a dryer according to one embodiment. FIG. 7 and FIG. 8 illustrate a detailed circuit structure of the circuit system illustrated in FIG. 6.

[0114] Referring to FIGS. 6, 7, and 8, the rectifier circuit (110) is connected to a commercial power source (AC) and can rectify AC power supplied from the commercial power source (AC). For example, the rectifier circuit (110) can convert a negative voltage of AC voltage into a positive voltage. The rectifier circuit (110) may include a full-wave rectifier circuit or a half-wave rectifier circuit. The rectifier circuit (110) may be provided as a bridge circuit including a plurality of diodes (D1, D2, D3, D4) connected in parallel and / or series. The output terminal of the rectifier circuit (110) may be connected to an input node (Vin) of an RF power supply unit (120). The AC voltage rectified by the rectifier circuit (110) may be input to the RF power supply unit (120).

[0115] The RF power supply unit (120) may be provided as a circuit including various elements for generating an RF signal. For example, the RF power supply unit (120) may include an electrolytic capacitor (Cpa1), a capacitor (Cpa2), a plurality of inductors (Lpa1, Lpa2), and a switching element (SW1). The electrolytic capacitor (Cpa1) may be connected to the Vin node and ground. The switching element (SW1) and the inductor (Lpa1) may be connected in series between the Vin node and ground. Additionally, the inductor (Lpa2) and the capacitor (Cpa2) connected in series may be placed between the N1 node connecting the switching element (SW1) and the inductor (Lpa1) and the impedance matching circuit (140).

[0116] The switching element (SW1) of the RF power supply unit (120) may correspond to a transistor. Depending on the operation of the switching element (SW1), the RF power supply unit (120) may be activated (ON) or deactivated (OFF). The operation of the RF power supply unit (120) may be controlled according to the switching signal applied to the switching element (SW1). When the switching element (SW1) is turned ON, the operation of the RF power supply unit (120) may be activated. When the switching element (SW1) is turned OFF, the operation of the RF power supply unit (120) may be deactivated.

[0117] The frequency control circuit (130) may include a plurality of D flip-flops (131-1, 131-2, ..., 131-N) connected in series. The N D flip-flops may be connected in a daisy chain manner. Each of the plurality of D flip-flops (131-1, 131-2, ..., 131-N) may include a data input pin (D), a clock pin (CLK), and an output pin (Q).

[0118] The frequency control circuit (130) may include a plurality of inverters (Inv1, Inv2, ..., InvN) that connect the data input pin (D) and output pin (Q) of each of the plurality of D flip-flops (131-1, 131-2, ..., 131-N). For example, if the output Q1 of the first D flip-flop (131-1) is inverted through an inverter and fed back to the D input, the first D flip-flop (131-1) can generate a frequency signal (fsw1) having a frequency corresponding to half the reference frequency. A reference frequency signal having a reference frequency can be generated by a frequency generator (FG). The reference frequency signal generated by the frequency generator (FG) can be input as the clock (CLK) of the first D flip-flop (131-1).

[0119] When multiple D flip-flops (131-1, 131-2, ..., 131-N) are connected in a daisy-chain manner, the second D flip-flop (131-2) can output a frequency signal (fsw2) having a frequency corresponding to 1 / 4 times the reference frequency, and the ND flip-flop (131-N) can output 1 / 2 of the reference frequency n It can output a frequency signal (fswN) having a frequency corresponding to the antinode.

[0120] The number of D flip-flops may vary depending on the design. For example, the frequency control circuit (130) may include three D flip-flops. The frequency control circuit (130) may include a first D flip-flop (131-1) having a first clock pin and a first output pin connected to a frequency generator (FG), a second D flip-flop (131-2) having a second clock pin and a second output pin connected to the first output pin of the first D flip-flop (131-1), and a third D flip-flop having a third clock pin and a third output pin connected to the second output pin of the second D flip-flop (131-2).

[0121] The frequency control circuit (130) may include a first comparator (134a) that outputs a first output value (sel1) by comparing the magnitude of the AC voltage (Vpa) with a first threshold value (Vth1), and a second comparator (134b) that outputs a second output value (sel2) by comparing the magnitude of the AC voltage (Vpa) with a second threshold value (Vth2). The first output value (sel1) of the first comparator (134a) and the second output value (sel2) of the second comparator (134b) may each correspond to a bit value.

[0122] The frequency control circuit (130) may include a multiplexer (132) for selecting one of a plurality of frequency signals. The first output value (sel1) of the first comparator (134a) and the second output value (sel2) of the second comparator (134b) may be input to the multiplexer (132). In other words, a 2-bit selection signal may be input to the multiplexer (132).

[0123] The multiplexer (132) can output one of a plurality of frequency signals output from each of a plurality of D flip-flops (131-1, 131-2, ..., 131-N) and a reference frequency signal output from a frequency generator (FG) as a switching signal based on the first output value (sel1) of the first comparator (134a) and the second output value (sel2) of the second comparator (134b).

[0124] The frequency control circuit (130) is exemplified as including two comparators, but is not limited thereto. The frequency control circuit (130) may include two or more comparators. Depending on the number of comparators, the number of intervals for dividing the magnitude of the AC voltage and the number of bits of the selection signal input to the multiplexer (132) may vary.

[0125] The frequency control circuit (130) may include a frequency shifter (133) that finely adjusts the frequency of a switching signal output from a multiplexer (132) within a predetermined range. The frequency shifter (133) can finely adjust the frequency of a frequency signal selected by the multiplexer (132) within a predetermined range. The frequency shifter (133) may include a voltage-controlled oscillator (VCO). The frequency shifter (133) can change the frequency of a switching signal output from the multiplexer (132) based on a voltage input from the control unit (300). The switching signal output from the frequency shifter (133) can be input to a switching element (SW1) of the RF power supply unit (120).

[0126] The impedance matching circuit (140) may be provided as a circuit in which a plurality of inductors (L), a plurality of capacitors (C), and a plurality of switches (S1, S2, S3, S4, S5, S6, S7, S8, S9) are connected in series and / or in parallel. The plurality of switches (S1, S2, S3, S4, S5, S6, S7, S8, S9) included in the impedance matching circuit (140) may be opened or closed under the control of the control unit (300). Impedance matching may be performed as the plurality of switches (S1, S2, S3, S4, S5, S6, S7, S8, S9) are controlled. The impedance matching circuit (140) is exemplified as including three inductors (L) connected in parallel, three capacitors (C) connected in parallel, and nine switches, but is not limited thereto. The structure of the impedance matching circuit (140) can be varied depending on the design.

[0127] An inductor (Le) for preventing / suppressing spark generation may be provided between the impedance matching circuit (140) and the electrode (90). In FIG. 7, the inductor (Le) is illustrated as being connected to the first electrode (90a), but is not limited thereto. An inductor for preventing / suppressing spark generation may also be provided between the second electrode (90b) and the impedance matching circuit (140).

[0128] The control unit (300) can perform impedance matching corresponding to the impedance change of the object by controlling the on-off of each of the plurality of switches (S1, S2, S3, S4, S5, S6, S7, S8, S9).

[0129] It is also possible to provide multiple impedance matching circuits (140) in correspondence with the provision of multiple electrodes (90). For example, one electrode (90) and one impedance matching circuit (140) may be provided as a set.

[0130] Figure 9 is a graph briefly illustrating the relationship between the change in the magnitude of the AC voltage and the frequency of the switching signal for turning the RF power supply on or off.

[0131] Referring to the graph (900) of FIG. 9, the dryer (1) can set a threshold value to divide the magnitude of the AC voltage input to the RF power supply unit (120) into multiple sections. The dryer (1) can drive the RF power supply unit (120) at a low switching frequency at a high voltage depending on the result of comparing the magnitude of the AC voltage with the threshold value.

[0132] In the range where the magnitude of the AC voltage (Vpa) is smaller than the first threshold value (Vth1), a relatively high switching frequency (fsw1) (e.g., 27.12 MHz) may be selected. In the range where the magnitude of the AC voltage (Vpa) is greater than or equal to the first threshold value (Vth1) and smaller than the second threshold value (Vth2), an intermediate switching frequency (fsw2) (e.g., 13.56 MHz) may be selected. In the range where the magnitude of the AC voltage (Vpa) is greater than or equal to the second threshold value (Vth2), a relatively low switching frequency (fsw3) (e.g., 6.78 MHz) may be selected. Fine adjustment of the selected switching frequency may be performed through a frequency shifter (133).

[0133] When driving the RF power supply unit (120) using a DC voltage, the RMS value of the AC voltage is input to the RF power supply unit (120). When driving the RF power supply unit (120) using an AC voltage, since the magnitude of the AC voltage changes instantaneously, the magnitude of the voltage input to the RF power supply unit (120) repeatedly increases and decreases over time.

[0134] When the magnitude of the voltage input to the RF power supply unit (120) is greater than the RMS value, more noise may be generated than when the RF power supply unit (120) is driven with a DC voltage. Unlike a general power converter, a power amplifier for applying a high-frequency electric field to a drying object is vulnerable to high-frequency noise because it operates at a very high frequency of 10 MHz or higher. The disclosed dryer (1) can reduce noise by setting the switching frequency for operating the RF power supply unit (120) lower as the magnitude of the voltage input to the RF power supply unit (120) increases.

[0135] Figure 10 is a graph showing the switching signal applied to the RF power supply according to the change in the magnitude of the AC voltage.

[0136] Referring to the graph (1000) of FIG. 10, the switching element (SW1) of the RF power supply unit (120) has an input voltage (V GS It can be turned on or off based on ). The on / off period of the switching element (SW1) can be determined by the frequency of the switching signal input to the switching element (SW1) (i.e., the switching frequency). The higher the frequency of the switching signal, the shorter the on / off period of the switching element (SW1).

[0137] The dryer (1) can determine the frequency of the switching signal to a relatively high switching frequency (fsw1) when the magnitude of the alternating voltage (Vpa) is smaller than the first threshold value (Vth1). The high switching frequency (fsw1) can correspond to a reference frequency (e.g., 27.12 MHz).

[0138] The dryer (1) can determine the frequency of the switching signal as an intermediate switching frequency (fsw2) if the magnitude of the alternating voltage (Vpa) is greater than or equal to the first threshold value (Vth1) and less than the second threshold value (Vth2). The intermediate switching frequency (fsw2) can correspond to a first frequency that is lower than the reference frequency.

[0139] The dryer (1) can determine the frequency of the switching signal to a relatively low switching frequency (fsw3) if the magnitude of the alternating voltage (Vpa) is greater than or equal to the second threshold value (Vth2). The low switching frequency (fsw3) can correspond to a second frequency that is lower than the first frequency.

[0140] The first threshold value (Vth1) and the second threshold value (Vth2) can be set in various ways depending on the design. Additionally, two threshold values ​​for dividing the magnitude of the AC voltage into multiple intervals have been exemplified, but are not limited thereto. The number of threshold values ​​may also vary depending on the design. Two or more threshold values ​​may be set to divide the magnitude of the AC voltage input to the RF power supply unit (120) into three or more.

[0141] There is a trade-off between drying performance and the specifications of the circuit system. A higher threshold increases drying performance, but there is a possibility that errors may occur in the operation of the circuit system due to high frequencies. Conversely, a lower threshold improves the stability of the circuit system, but there is a possibility that drying performance may decrease as the operating range at high frequencies is reduced. The threshold can be selected by considering these trade-offs.

[0142] For example, since the waveform of the AC voltage output from the AC power source is a sine wave, the RMS value of the AC voltage is 0.707 times the peak voltage (Vpeak). The second threshold value (Vth2) can be set to 0.707 times the peak voltage (Vpeak). The first threshold value (Vth1) can be set to 0.35 times the peak voltage (Vpeak). The first threshold value (Vth1) can correspond to 50% of the second threshold value (Vth2).

[0143] Figure 11 is a graph illustrating the operation of a frequency control circuit that determines the frequency of a switching signal applied to an RF power supply according to changes in the magnitude of the AC voltage.

[0144] As described above, the frequency control circuit (130) may include a multiplexer (132), a first comparator (134a), and a second comparator (134b). The first comparator (134a) may output a first output value (sel1) by comparing the magnitude of the AC voltage (Vpa) with a first threshold value (Vth1). The second comparator (134b) may output a second output value (sel2) by comparing the magnitude of the AC voltage (Vpa) with a second threshold value (Vth2).

[0145] Referring to the graph (1100) of FIG. 11, the first output value (sel1) of the first comparator (134a) and the second output value (sel2) of the second comparator (134b) may each correspond to a bit value. The first output value (sel1) and the second output value (sel2) each have 1 bit, and a selection signal having 2 bits may be input to the multiplexer (132).

[0146] The multiplexer (132) can output one of a plurality of frequency signals output from each of a plurality of D flip-flops (131-1, 131-2, ..., 131-N) and a reference frequency signal output from a frequency generator (FG) as a switching signal in response to input of a selection signal.

[0147] For example, when the selection signal is 00, the multiplexer (132) can select a reference frequency signal having a reference frequency (e.g., 27.12 MHz) as a switching signal. When the selection signal is 10, the multiplexer (132) can select a first frequency signal having a first frequency (e.g., 13.56 MHz) as a switching signal. When the selection signal is 11, the multiplexer (132) can select a second frequency signal having a second frequency (e.g., 6.78 MHz) as a switching signal.

[0148] It is exemplified that a 2-bit selection signal is input to the multiplexer (132), but is not limited thereto. The frequency control circuit (130) may include two or more comparators. Depending on the number of comparators, the number of bits of the selection signal input to the multiplexer (132) may vary.

[0149] FIG. 12 is a flowchart illustrating a control method for a dryer according to one embodiment.

[0150] Referring to FIG. 12, the dryer (1) can identify a change in the magnitude of the alternating voltage applied to the RF power supply unit (120) (1201). For example, the frequency control circuit (130) and / or control unit (300) of the dryer (1) can identify the instantaneous value of the alternating voltage applied to the RF power supply unit (120). The dryer (1) can identify whether the magnitude (i.e., instantaneous value) of the alternating voltage applied to the RF power supply unit (120) increases or decreases.

[0151] The dryer (1) can adjust the frequency of a switching signal to turn the RF power supply (120) on or off based on a change in the magnitude of the AC voltage (1202). The frequency of the switching signal may also be referred to as the 'switching frequency'. For example, the frequency control circuit (130) can determine the frequency of the switching signal to control the operation of the RF power supply (120) to be smaller as the magnitude of the AC voltage increases.

[0152] The frequency control circuit (130) of the dryer (1) can divide the magnitude of the AC voltage that changes over time into multiple intervals. For example, the control unit (300) of the dryer (1) can divide the magnitude of the AC voltage into multiple intervals and set multiple threshold values ​​to determine the switching frequency corresponding to each interval. The frequency control circuit (130) can compare the magnitude of the AC voltage with the multiple threshold values ​​and determine a different switching frequency for controlling the operation of the RF power supply unit (120) for each interval.

[0153] Each of the plurality of comparators (134a, 134b) included in the frequency control circuit (130) can output a result of comparing the magnitude of the AC voltage and a plurality of threshold values ​​as a bit value. The bit value output from each of the plurality of comparators (134a, 134b) can be input to the multiplexer (132) as a selection signal.

[0154] The multiplexer (132) can output one of a plurality of frequency signals output from each of a plurality of D flip-flops (131-1, 131-2, ..., 131-N) and a reference frequency signal output from a frequency generator (FG) as a switching signal in response to input of a selection signal.

[0155] The frequency of the switching signal output from the multiplexer (132) can be finely adjusted within a predetermined range by the frequency shifter (133). The switching signal having the finely adjusted frequency can be input to the switching element (SW1) of the RF power supply (120). The switching element (SW1) can repeatedly turn on and off based on the switching signal. Depending on whether the switching element (SW1) is on or off, the RF power supply (120) can be activated (ON) or deactivated (OFF).

[0156] In this way, the disclosed dryer (1) can use an alternating voltage to operate the RF power supply (120) and adjust the switching frequency to control the RF power supply (120). Through this, the complexity of the circuit system can be reduced while minimizing the generation of high-frequency noise caused by the use of alternating voltage.

[0157] Figure 13 is a flowchart that explains in more detail the control method of the dryer described in Figure 12.

[0158] Referring to FIG. 13, the dryer (1) can identify a change in the magnitude of the alternating voltage applied to the RF power supply unit (120) (1301). Step 1301 corresponds to step 1201 of FIG. 12.

[0159] The frequency control circuit (130) of the dryer (1) can determine the frequency of the switching signal as a reference frequency if the magnitude of the AC voltage is smaller than a first threshold value (1302, 1303). The frequency control circuit (130) can determine the frequency of the switching signal as a first frequency lower than the reference frequency if the magnitude of the AC voltage is greater than or equal to the first threshold value and smaller than a second threshold value (1304, 1305). The second threshold value can be set to be greater than the first threshold value. The frequency control circuit (130) can determine the frequency of the switching signal as a second frequency lower than the first frequency if the magnitude of the AC voltage is greater than or equal to the second threshold value (1306).

[0160] Although it has been exemplified that the switching frequency of the RF power supply unit (120) is adjusted by dividing the magnitude of the AC voltage input to the RF power supply unit (120) into three sections, it is not limited thereto. The magnitude of the AC voltage may be divided into three or more sections, and a switching frequency corresponding to each section may be determined.

[0161] A dryer according to one embodiment may include: a chamber; a first electrode disposed on a first side of the chamber; a second electrode disposed on a second side of the chamber facing the first side; an RF power supply unit that operates by an alternating current voltage input from an alternating current power source and applies an RF signal to the first electrode and the second electrode; an impedance matching circuit that performs impedance matching between the first electrode and the second electrode and the RF power supply unit; and a frequency control circuit that adjusts the frequency of a switching signal to turn the RF power supply unit on or off based on a change in the magnitude of the alternating current voltage.

[0162] The above frequency control circuit can determine the frequency of the switching signal to be smaller as the magnitude of the AC voltage increases.

[0163] The frequency control circuit can determine the frequency of the switching signal as a reference frequency if the magnitude of the AC voltage is smaller than a first threshold value. The frequency control circuit can determine the frequency of the switching signal as a first frequency lower than the reference frequency if the magnitude of the AC voltage is greater than or equal to the first threshold value and smaller than a second threshold value. The second threshold value may be greater than the first threshold value. The frequency control circuit can determine the frequency of the switching signal as a second frequency lower than the first frequency if the magnitude of the AC voltage is greater than or equal to the second threshold value.

[0164] The frequency control circuit may include: a plurality of D flip-flops connected in series; a first comparator that outputs a first output value by comparing the magnitude of the AC voltage with the first threshold value; a second comparator that outputs a second output value by comparing the magnitude of the AC voltage with the second threshold value; and a multiplexer that outputs one of a plurality of frequency signals output from each of the plurality of D flip-flops and a reference frequency signal output from a frequency generator as the switching signal based on the first output value and the second output value.

[0165] The above frequency control circuit may further include a frequency shifter that finely adjusts the frequency of the switching signal output from the multiplexer within a predetermined range.

[0166] The above frequency control circuit may further include an inverter connecting the data input pin and output pin of each of the plurality of D flip-flops.

[0167] The plurality of D flip-flops may include: a first D flip-flop including a first clock pin and a first output pin connected to the frequency generator; a second D flip-flop including a second clock pin and a second output pin connected to the first output pin of the first D flip-flop; and a third D flip-flop including a third clock pin and a third output pin connected to the second output pin of the second D flip-flop.

[0168] A control method for a dryer comprising an RF power supply unit that operates by an AC voltage input from an AC power source and applies an RF signal to a first electrode and a second electrode, and an impedance matching circuit that performs impedance matching between the first electrode and the second electrode and the RF power supply unit, wherein the control method according to one embodiment may include: identifying a change in the magnitude of the AC voltage by means of a frequency control circuit; and adjusting the frequency of a switching signal for turning the RF power supply unit on or off based on the change in the magnitude of the AC voltage by means of the frequency control circuit.

[0169] Adjusting the frequency of the switching signal may include determining the frequency of the switching signal to be smaller as the magnitude of the alternating voltage increases.

[0170] Adjusting the frequency of the switching signal may include: determining the frequency of the switching signal as a reference frequency if the magnitude of the AC voltage is smaller than a first threshold value; determining the frequency of the switching signal as a first frequency lower than the reference frequency if the magnitude of the AC voltage is greater than or equal to the first threshold value and smaller than a second threshold value, wherein the second threshold value is greater than the first threshold value; and determining the frequency of the switching signal as a second frequency lower than the first frequency if the magnitude of the AC voltage is greater than or equal to the second threshold value.

[0171] The disclosed dryer and control method can drive an RF power supply unit using AC power supplied from an AC power source. The disclosed dryer and control method may not require a circuit structure and control process for driving an RF power supply unit using DC power. Therefore, compared to the prior art, the size of the circuit and the manufacturing cost of the circuit are reduced, and the circuit control method can be simplified.

[0172] The disclosed dryer and control method can minimize high-frequency noise by adjusting the switching frequency for controlling the RF power supply according to the magnitude of the AC voltage.

[0173] In addition, the disclosed dryer and control method enable adaptive impedance matching by adjusting the switching frequency corresponding to the AC voltage, and can adaptively respond to changes in load impedance due to the movement of the object to be dried and the progress of drying.

[0174] Meanwhile, the disclosed embodiments may be implemented in the form of a storage medium that stores instructions executable by a computer. The instructions may be stored in the form of program code, and when executed by a processor, they may generate a program module to perform the operation of the disclosed embodiments.

[0175] A device-readable storage medium may be provided in the form of a non-transitory storage medium. Here, 'non-transitory storage medium' simply means that it is a tangible device and does not contain a signal (e.g., electromagnetic waves), and the term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily. For example, a 'non-transitory storage medium' may include a buffer in which data is stored temporarily.

[0176] Methods according to the various embodiments disclosed in this document may be provided as part of a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or distributed online (e.g., download or upload) through an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., downloadable app) may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0177] As described above, the disclosed embodiments have been explained with reference to the attached drawings. Those skilled in the art will understand that the present invention may be practiced in forms different from the disclosed embodiments without changing the technical spirit or essential features of the invention. The disclosed embodiments are illustrative and should not be interpreted restrictively.

Claims

1. Chamber; A first electrode disposed on the first side of the chamber; A second electrode disposed on the second side of the chamber facing the first side; An RF power supply unit that operates by an AC voltage received from an AC power source and applies an RF signal to the first electrode and the second electrode; An impedance matching circuit that performs impedance matching between the first electrode and the second electrode and the RF power supply unit; and A dryer comprising: a frequency control circuit for adjusting the frequency of a switching signal to turn the RF power supply on or off based on a change in the magnitude of the above AC voltage.

2. In Paragraph 1, The above frequency control circuit is, A dryer that determines the frequency of the switching signal to be smaller as the magnitude of the above alternating voltage increases.

3. In Paragraph 1, The above frequency control circuit is, If the magnitude of the above AC voltage is smaller than the first threshold value, the frequency of the switching signal is determined as the reference frequency, and If the magnitude of the above AC voltage is greater than or equal to the first threshold value and less than the second threshold value, the frequency of the switching signal is determined to be a first frequency lower than the reference frequency, and the second threshold value is greater than the first threshold value, and A dryer that determines the frequency of the switching signal to a second frequency lower than the first frequency when the magnitude of the above alternating voltage is greater than or equal to the above second threshold value.

4. In Paragraph 3, The above frequency control circuit is Multiple D flip-flops connected in series; A first comparator that outputs a first output value by comparing the magnitude of the above AC voltage and the above first threshold value; A second comparator that outputs a second output value by comparing the magnitude of the AC voltage and the second threshold value; and A dryer comprising: a multiplexer that outputs one of a plurality of frequency signals output from each of the plurality of D flip-flops and a reference frequency signal output from a frequency generator as the switching signal based on the first output value and the second output value.

5. In Paragraph 4, The above frequency control circuit is A dryer further comprising a frequency shifter including a circuit that adjusts the frequency of the switching signal output from the multiplexer within a predetermined range.

6. In Paragraph 4, The above frequency control circuit is A dryer further comprising an inverter connecting the data input pin and output pin of each of the plurality of D flip-flops.

7. In Paragraph 5, The above plurality of D flip-flops are A first D flip-flop including a first clock pin and a first output pin connected to the frequency generator above; A second D flip-flop comprising a second clock pin and a second output pin connected to a first output pin of the first D flip-flop; and A dryer comprising a third D flip-flop including a third clock pin and a third output pin connected to the second output pin of the second D flip-flop.

8. In Paragraph 4, A dryer in which the first output value of the first comparator and the second output value of the second comparator each include a bit value.

9. A method for controlling a dryer comprising an RF power supply unit that operates by an AC voltage input from an AC power source and applies an RF signal to a first electrode and a second electrode, and an impedance matching circuit that performs impedance matching between the first electrode and the second electrode and the RF power supply unit, Identifying changes in the magnitude of the AC voltage by means of a frequency control circuit; A method for controlling a dryer, comprising: adjusting the frequency of a switching signal for turning the RF power supply on or off based on a change in the magnitude of the AC voltage by the above frequency control circuit.

10. In Paragraph 9, Adjusting the frequency of the above switching signal is, A method for controlling a dryer comprising determining the frequency of the switching signal to be smaller as the magnitude of the AC voltage increases.

11. In Paragraph 9, Adjusting the frequency of the above switching signal is, If the magnitude of the above AC voltage is smaller than the first threshold value, the frequency of the switching signal is determined as the reference frequency; If the magnitude of the AC voltage is greater than or equal to the first threshold value and less than the second threshold value, the frequency of the switching signal is determined to be a first frequency lower than the reference frequency, and the second threshold value is greater than the first threshold value; A method for controlling a dryer comprising: determining the frequency of the switching signal to a second frequency lower than the first frequency when the magnitude of the alternating voltage is greater than or equal to the second threshold value.

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