Patent Publication Number: US-2023140320-A1

Title: Electronic device including structure for detecting rotation amount of motor

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/KR2022/010232 designating the United States, filed on Jul. 13, 2022, in the Korean Intellectual Property Receiving Office and claiming priority to Korean Patent Application No. 10-2021-0148817, filed on Nov. 2, 2021, in the Korean Intellectual Property Office, and to Korean Patent Application No. 10-2021-0173251, filed on Dec. 6, 2021, in the Korean Intellectual Property Office, the disclosures of all of which are incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     Field 
     The disclosure relates to an electronic device including a structure for detecting a rotation amount of a motor. 
     Description of Related Art 
     A portable electronic device such as a mobile device has enhanced a user portability through weight lightening and miniaturization. A width of a display bezel has decreased, and a thickness of the electronic device has decreased to miniaturize the electronic device. Even though the electronic device is miniaturized, a development of an electronic device applying a flexible display is in progress as there is a demand for the enlargement of the display. 
     In order to implement a large screen of a display and maintain portability of an electronic device, a structure for changing a display area of the display has been developed. A flexible display may have a foldable type in which displays are folded with each other, and a rollable type in which a portion of the display is rolled and stored in a housing, and is exposed to the outside of the housing when necessary. 
     Since the flexible display has a structure in which the display area of the display is changed, the electronic device including the flexible display may be required to change the display area of the flexible display or change UX. In order to change the display area of the flexible display, the electronic device may provide a method of identifying a movement distance of the flexible display to understand a degree to which the flexible display is exposed to the outside. 
     The technical problems to be achieved in this disclosure are not limited to those described above, and other technical problems not mentioned herein will be clearly understood by those having ordinary knowledge in the art to which the present disclosure belongs, from the following description. 
     SUMMARY 
     According to an example embodiment, an electronic device may comprise: a first housing, a second housing slidably coupled to the first housing, a rollable display configured to be enlarged or reduced based on a movement of the second housing, a rack gear disposed on the second housing, a pinion gear driven in engagement with the rack gear, an actuator configured to rotate the pinion gear and coupled with the pinion gear by a shaft, a first magnet surrounding at least part of the shaft, and spaced apart from the pinion gear along to the shaft, and a hall sensor spaced apart from the pinion gear in a direction perpendicular to the shaft, and a processor, wherein the processor is configured to obtain data related to a change in the magnetic force using the hall sensor and identify a rotating angle of the pinion gear based on the data related to a change in the magnetic force. 
     According to an example embodiment, a power transmission device may comprise: a motor housing including a first space and a second space distinct from the first space, a motor disposed within the first space in the motor housing, a shaft disposed within the second space extending from the motor and configured to be rotated by the motor, a partition wall separating the first space and the second space, a pinion gear disposed within the second space coupled to the shaft and including a plurality of teeth, a magnet surrounding a portion of the shaft and spaced apart from the pinion gear along to the shaft, and a hall sensor spaced apart from the pinion gear in a direction perpendicular to the rotating axis direction of the shaft, and configured to detect a magnetic force transmitted from the magnet through the shaft and the pinion gear. 
     An electronic device according to an embodiment can identify a movement distance of a flexible display by detecting a rotation angle of a motor. 
     An electronic device according to an embodiment can improve mounting efficiency of an internal space of the electronic device by fixing a magnet and a hall sensor for detecting movement of the flexible display to a designated position. 
     An electronic device according to an embodiment can change a size of a display area according to a change in a size of the flexible display by identifying an amount and direction of movement of the flexible display, and can change and provide a user environment provided through the display area. 
     The effects that can be obtained from the present disclosure are not limited to those described above, and any other effects not mentioned herein will be clearly understood by those having ordinary knowledge in the art to which the present disclosure belongs, from the following description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and advantages of certain embodiments of the present disclosure will be more apparent from the following detailed description, taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a block diagram illustrating an example electronic device in a network environment according to an embodiment; 
         FIG.  2 A  is a perspective view illustrating an electronic device in a first state, according to an embodiment; 
         FIG.  2 B  is a perspective view illustrating an electronic device in a second state according to an embodiment; 
         FIG.  3    is a diagram illustrating an internal structure in which a display of an electronic device is removed, according to an embodiment; 
         FIG.  4    is an enlarged view of area A of  FIG.  3    of an electronic device according to an embodiment; 
         FIG.  5 A  is a perspective view illustrating an electronic device and a power transmission structure of the electronic device, according to an embodiment; 
         FIG.  5 B  is a perspective view illustrating a structure of a power transmission device according to an embodiment; 
         FIG.  6    is a cross-sectional view of the power transmission device of  FIG.  5 A  taken along line B-B′ according to an embodiment; 
         FIG.  7    is a diagram illustrating a magnetic force line formed in components of a power transmission device according to an embodiment; 
         FIGS.  8 A and  8 B  are diagrams illustrating a positional relationship between a gear tooth of a pinion gear of a power transmission device and a hall sensor according to an embodiment; 
         FIGS.  9 A and  9 B  are diagrams illustrating examples of various arrangements of magnets in a power transmission device, according to an embodiment; 
         FIG.  10 A  is a diagram illustrating a magnetic force distribution formed surround a power transmission device according to an embodiment; 
         FIG.  10 B  is a diagram illustrating a magnetic force distribution formed surround a power transmission device including a metal for magnetic induction, according to an embodiment; 
         FIG.  11 A  is a diagram illustrates a relationship between a rotation angle of a pinion gear of a power transmission device and a hall sensor according to an embodiment; and 
         FIGS.  11 B and  11 C  are graphs illustrating a change in a magnetic field magnitude according to a position of a pinion gear of a power transmission device, according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
       FIG.  1    is a block diagram illustrating an example electronic device in a network environment according to an embodiment of the disclosure. 
     Referring to  FIG.  1   , an electronic device  101  in a network environment  100  may communicate with an electronic device  102  via a first network  198  (e.g., a short-range wireless communication network), or at least one of an electronic device  104  or a server  108  via a second network  199  (e.g., a long-range wireless communication network). According to an embodiment of the disclosure, the electronic device  101  may communicate with the electronic device  104  via the server  108 . According to an embodiment of the disclosure, the electronic device  101  may include a processor  120 , a memory  130 , an input module  150 , a sound output module  155 , a display module  160 , an audio module  170 , a sensor module  176 , an interface  177 , a connecting terminal  178 , a haptic module  179 , a camera module  180 , a power management module  188 , a battery  189 , a communication module  190 , a subscriber identification module (SIM)  196 , or an antenna module  197 . In an embodiment of the disclosure, at least one of the components (e.g., the connecting terminal  178 ) may be omitted from the electronic device  101 , or one or more other components may be added in the electronic device  101 . In an embodiment of the disclosure, some of the components (e.g., the sensor module  176 , the camera module  180 , or the antenna module  197 ) may be implemented as a single component (e.g., the display module  160 ). 
     The processor  120  may execute, for example, software (e.g., a program  140 ) to control at least one other component (e.g., a hardware or software component) of the electronic device  101  coupled with the processor  120 , and may perform various data processing or computation. According to an embodiment of the disclosure, as at least part of the data processing or computation, the processor  120  may store a command or data received from another component (e.g., the sensor module  176  or the communication module  190 ) in a volatile memory  132 , process the command or the data stored in the volatile memory  132 , and store resulting data in a non-volatile memory  134 . According to an embodiment of the disclosure, the processor  120  may include a main processor  121  (e.g., a central processing unit (CPU) or an application processor (AP)), or an auxiliary processor  123  (e.g., a graphics processing unit (GPU), a neural processing unit (NPU), an image signal processor (ISP), a sensor hub processor, or a communication processor (CP)) that is operable independently from, or in conjunction with, the main processor  121 . For example, when the electronic device  101  includes the main processor  121  and the auxiliary processor  123 , the auxiliary processor  123  may be adapted to consume less power than the main processor  121 , or to be specific to a specified function. The auxiliary processor  123  may be implemented as separate from, or as part of the main processor  121 . 
     The auxiliary processor  123  may control at least some of functions or states related to at least one component (e.g., the display module  160 , the sensor module  176 , or the communication module  190 ) among the components of the electronic device  101 , instead of the main processor  121  while the main processor  121  is in an inactive (e.g., sleep) state, or together with the main processor  121  while the main processor  121  is in an active state (e.g., executing an application). According to an embodiment of the disclosure, the auxiliary processor  123  (e.g., an image signal processor or a communication processor) may be implemented as part of another component (e.g., the camera module  180  or the communication module  190 ) functionally related to the auxiliary processor  123 . According to an embodiment of the disclosure, the auxiliary processor  123  (e.g., the neural processing unit) may include a hardware structure specified for artificial intelligence model processing. An artificial intelligence model may be generated by machine learning. Such learning may be performed, e.g., by the electronic device  101  where the artificial intelligence is performed or via a separate server (e.g., the server  108 ). Learning algorithms may include, but are not limited to, e.g., supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning. The artificial intelligence model may include a plurality of artificial neural network layers. The artificial neural network may be a deep neural network (DNN), a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted Boltzmann machine (RBM), a deep belief network (DBN), a bidirectional recurrent deep neural network (BRDNN), deep Q-network or a combination of two or more thereof but is not limited thereto. The artificial intelligence model may, additionally or alternatively, include a software structure other than the hardware structure. 
     The memory  130  may store various data used by at least one component (e.g., the processor  120  or the sensor module  176 ) of the electronic device  101 . The various data may include, for example, software (e.g., the program  140 ) and input data or output data for a command related thereto. The memory  130  may include the volatile memory  132  or the non-volatile memory  134 . 
     The program  140  may be stored in the memory  130  as software, and may include, for example, an operating system (OS)  142 , middleware  144 , or an application  146 . 
     The input module  150  may receive a command or data to be used by another component (e.g., the processor  120 ) of the electronic device  101 , from the outside (e.g., a user) of the electronic device  101 . The input module  150  may include, for example, a microphone, a mouse, a keyboard, a key (e.g., a button), or a digital pen (e.g., a stylus pen). 
     The sound output module  155  may output sound signals to the outside of the electronic device  101 . The sound output module  155  may include, for example, a speaker or a receiver. The speaker may be used for general purposes, such as playing multimedia or playing record. The receiver may be used for receiving incoming calls. According to an embodiment of the disclosure, the receiver may be implemented as separate from, or as part of the speaker. 
     The display module  160  may visually provide information to the outside (e.g., a user) of the electronic device  101 . The display module  160  may include, for example, a display, a hologram device, or a projector and control circuitry to control a corresponding one of the display, hologram device, and projector. According to an embodiment of the disclosure, the display module  160  may include a touch sensor adapted to detect a touch, or a pressure sensor adapted to measure the intensity of force incurred by the touch. 
     The audio module  170  may convert a sound into an electrical signal and vice versa. According to an embodiment of the disclosure, the audio module  170  may obtain the sound via the input module  150 , or output the sound via the sound output module  155  or a headphone of an external electronic device (e.g., an electronic device  102 ) directly (e.g., wiredly) or wirelessly coupled with the electronic device  101 . 
     The sensor module  176  may detect an operational state (e.g., power or temperature) of the electronic device  101  or an environmental state (e.g., a state of a user) external to the electronic device  101 , and then generate an electrical signal or data value corresponding to the detected state. According to an embodiment of the disclosure, the sensor module  176  may include, for example, a gesture sensor, a gyro sensor, an atmospheric pressure sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an infrared (IR) sensor, a biometric sensor, a temperature sensor, a humidity sensor, or an illuminance sensor. 
     The interface  177  may support one or more specified protocols to be used for the electronic device  101  to be coupled with the external electronic device (e.g., the electronic device  102 ) directly (e.g., wiredly) or wirelessly. According to an embodiment of the disclosure, the interface  177  may include, for example, a high-definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, or an audio interface. 
     A connecting terminal  178  may include a connector via which the electronic device  101  may be physically connected with the external electronic device (e.g., the electronic device  102 ). According to an embodiment of the disclosure, the connecting terminal  178  may include, for example, a HDMI connector, a USB connector, a SD card connector, or an audio connector (e.g., a headphone connector). 
     The haptic module  179  may convert an electrical signal into a mechanical stimulus (e.g., a vibration or a movement) or electrical stimulus which may be recognized by a user via his tactile sensation or kinesthetic sensation. According to an embodiment of the disclosure, the haptic module  179  may include, for example, a motor, a piezoelectric element, or an electric stimulator. 
     The camera module  180  may capture a still image or moving images. According to an embodiment of the disclosure, the camera module  180  may include one or more lenses, image sensors, image signal processors, or flashes. 
     The power management module  188  may manage power supplied to the electronic device  101 . According to an embodiment of the disclosure, the power management module  188  may be implemented as at least part of, for example, a power management integrated circuit (PMIC). 
     The battery  189  may supply power to at least one component of the electronic device  101 . According to an embodiment of the disclosure, the battery  189  may include, for example, a primary cell which is not rechargeable, a secondary cell which is rechargeable, or a fuel cell. 
     The communication module  190  may support establishing a direct (e.g., wired) communication channel or a wireless communication channel between the electronic device  101  and the external electronic device (e.g., the electronic device  102 , the electronic device  104 , or the server  108 ) and performing communication via the established communication channel. The communication module  190  may include one or more communication processors that are operable independently from the processor  120  (e.g., the application processor (AP)) and supports a direct (e.g., wired) communication or a wireless communication. According to an embodiment of the disclosure, the communication module  190  may include a wireless communication module  192  (e.g., a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module  194  (e.g., a local area network (LAN) communication module or a power line communication (PLC) module). A corresponding one of these communication modules may communicate with the external electronic device via the first network  198  (e.g., a short-range communication network, such as Bluetooth™, wireless-fidelity (Wi-Fi) direct, or infrared data association (IrDA)) or the second network  199  (e.g., a long-range communication network, such as a legacy cellular network, a 5G network, a next-generation communication network, the Internet, or a computer network (e.g., LAN or wide area network (WAN)). These various types of communication modules may be implemented as a single component (e.g., a single chip), or may be implemented as multi components (e.g., multi chips) separate from each other. The wireless communication module  192  may identify and authenticate the electronic device  101  in a communication network, such as the first network  198  or the second network  199 , using subscriber information (e.g., international mobile subscriber identity (IMSI)) stored in the subscriber identification module  196 . 
     The wireless communication module  192  may support a 5G network, after a 4G network, and next-generation communication technology, e.g., new radio (NR) access technology. The NR access technology may support enhanced mobile broadband (eMBB), massive machine type communications (mMTC), or ultra-reliable and low-latency communications (URLLC). The wireless communication module  192  may support a high-frequency band (e.g., the mmWave band) to address, e.g., a high data transmission rate. The wireless communication module  192  may support various technologies for securing performance on a high-frequency band, such as, e.g., beamforming, massive multiple-input and multiple-output (massive MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beam-forming, or large scale antenna. The wireless communication module  192  may support various requirements specified in the electronic device  101 , an external electronic device (e.g., the electronic device  104 ), or a network system (e.g., the second network  199 ). According to an embodiment of the disclosure, the wireless communication module  192  may support a peak data rate (e.g., 20 Gbps or more) for implementing eMBB, loss coverage (e.g., 164 dB or less) for implementing mMTC, or U-plane latency (e.g., 0.5 ms or less for each of downlink (DL) and uplink (UL), or a round trip of 1 ms or less) for implementing URLLC. 
     The antenna module  197  may transmit or receive a signal or power to or from the outside (e.g., the external electronic device) of the electronic device  101 . According to an embodiment of the disclosure, the antenna module  197  may include an antenna including a radiating element including a conductive material or a conductive pattern formed in or on a substrate (e.g., a printed circuit board (PCB)). According to an embodiment of the disclosure, the antenna module  197  may include a plurality of antennas (e.g., array antennas). In such a case, at least one antenna appropriate for a communication scheme used in the communication network, such as the first network  198  or the second network  199 , may be selected, for example, by the communication module  190  (e.g., the wireless communication module  192 ) from the plurality of antennas. The signal or the power may then be transmitted or received between the communication module  190  and the external electronic device via the selected at least one antenna. According to an embodiment of the disclosure, another component (e.g., a radio frequency integrated circuit (RFIC)) other than the radiating element may be additionally formed as part of the antenna module  197 . 
     According to certain embodiments of the disclosure, the antenna module  197  may be a mmWave antenna module. According to an embodiment of the disclosure, the mmWave antenna module may include a printed circuit board, a RFIC disposed on a first surface (e.g., the bottom surface) of the printed circuit board, or adjacent to the first surface and capable of supporting a designated high-frequency band (e.g., the mmWave band), and a plurality of antennas (e.g., array antennas) disposed on a second surface (e.g., the top or a side surface) of the printed circuit board, or adjacent to the second surface and capable of transmitting or receiving signals of the designated high-frequency band. 
     At least some of the above-described components may be coupled mutually and communicate signals (e.g., commands or data) therebetween via an inter-peripheral communication scheme (e.g., a bus, general purpose input and output (GPIO), serial peripheral interface (SPI), or mobile industry processor interface (MIPI)). 
     According to an embodiment of the disclosure, commands or data may be transmitted or received between the electronic device  101  and the external electronic device  104  via the server  108  coupled with the second network  199 . Each of the electronic devices  102  or  104  may be a device of a same type as, or a different type, from the electronic device  101 . According to an embodiment of the disclosure, all or some of operations to be executed at the electronic device  101  may be executed at one or more of the external electronic devices  102 ,  104 , or  108 . For example, if the electronic device  101  should perform a function or a service automatically, or in response to a request from a user or another device, the electronic device  101 , instead of, or in addition to, executing the function or the service, may request the one or more external electronic devices to perform at least part of the function or the service. The one or more external electronic devices receiving the request may perform the at least part of the function or the service requested, or an additional function or an additional service related to the request, and transfer an outcome of the performing to the electronic device  101 . The electronic device  101  may provide the outcome, with or without further processing of the outcome, as at least part of a reply to the request. To that end, a cloud computing, distributed computing, mobile edge computing (MEC), or client-server computing technology may be used, for example. The electronic device  101  may provide ultra-low latency services using, e.g., distributed computing or mobile edge computing. In an embodiment of the disclosure, the external electronic device  104  may include an internet-of-things (IoT) device. The server  108  may be an intelligent server using machine learning and/or a neural network. According to an embodiment of the disclosure, the external electronic device  104  or the server  108  may be included in the second network  199 . The electronic device  101  may be applied to intelligent services (e.g., smart home, smart city, smart car, or healthcare) based on 5G communication technology or IoT-related technology. 
       FIG.  2 A  is a perspective view illustrating an electronic device in a first state, according to an embodiment, and  FIG.  2 B  is a perspective view illustrating an electronic device in a second state according to an embodiment. 
     Referring to  FIGS.  2 A and  2 B , an electronic device  200  may comprise a first housing  210  and a second housing  220  movably coupled to a portion of the first housing  210 . According to an embodiment, the first housing  210  may include a first surface  211 , a second surface  212  facing the first surface  211 , and a first side frame  213  extending substantially in a perpendicular direction (e.g., in the z-axis direction) along a periphery of the first surface  211 . According to an embodiment, the first side frame  213  may include a first side surface  2131 , a second side surface  2132  extending from one end of the first side surface  2131 , and a third side surface  2133  extending from another end of the first side surface  2131 . According to an embodiment, the first housing  210  may include a first space that is at least partially closed from the outside through the first surface  211  and the first side frame  213 . 
     According to an embodiment, the second housing  220  may include a third surface  221 , a fourth surface  222  facing the third surface  221 , and a second side frame  223  extending substantially in a perpendicular direction (e.g., in the z-axis direction) along a periphery of the third surface  221 . According to an embodiment, the second side frame  223  may include a fourth side surface  2231  facing in an opposite direction to the first side surface  2131 , a fifth side surface  2232  extending from one end of the fourth side surface  2231  and coupled to a portion of the second side surface  2132 , and a sixth side surface  2233  extending from another end of the fourth side surface  2231  and at least partially coupled to the third side surface  2133 . In an embodiment, the fourth side surface  2231  may extend from a structure other than the third side surface  221  and may be coupled to the third side surface  221 . 
     According to an embodiment, the first surface  211  of the first housing  210  and the second surface  221  of the second housing  220  may be substantially the same plane. 
     According to an embodiment, the second housing  220  may include a second space that is at least partially closed from the outside through the third surface  221 , the fourth surface  222 , and the second side frame  223 . According to an embodiment, the first surface  211  and the third surface  221  may be disposed to form a rear surface of the electronic device  200  at least partially. For example, the first surface  211 , the third surface  221 , the first side frame  213 , and the second side frame  223  may be formed of a polymer, a coated or colored glass, a ceramic, a metal (e.g., aluminum, stainless steel (SUS), or magnesium), or a combination of at least two of the materials. 
     According to an embodiment, the electronic device  200  may include a flexible display  230  disposed to be supported by the first housing  210  and the second housing  220 . According to an embodiment, the flexible display  230  may include a plane portion supported by the second housing  220  and a bendable portion extending from the plane portion and supported by the first housing  210 . For example, the flexible display  230  may be disposed on the first surface  211  of the first housing  210  and the third surface  221  of the second housing  220 . The flexible display  230  may be formed as a substantially continuous surface by the first surface  211  and the third surface  221  formed as substantially the same surface. 
     According to an embodiment, the bendable portion of the flexible display  230  may be disposed so as not to be exposed (e.g., visible. As used herein, the terms “exposed” and “visible” may be used interchangeably to describe the bendable or hidden portions of the extendible display when the display is extended or the display is enlarged) to the outside in the first space of the first housing  210  in a state in which the electronic device  200  is closed, and exposed to the outside so as to extend from the plane portion while being supported by the first housing  210  in a state in which the electronic device  200  is opened. Accordingly, the electronic device  200  may be an electronic device of rollable type in which a display screen of the flexible display  230  is enlarged according to an opening operation according to movement of the first housing  210  from the second housing  220 . 
     According to an embodiment, the first housing  210  of the electronic device  200  may be at least partially inserted into the second space of the second housing  220  and movably coupled to a portion of the second housing in an x-axis direction. 
     According to an embodiment, in an open state, the flexible display  230  may be supported by the first housing  210  and/or the second housing  220  so that both ends have curved edges. 
     According to an embodiment, the electronic device  200  may automatically change to an open state and a closed state through a power transmission device (e.g., the power transmission device  300  of  FIG.  3   ) disposed in the first space and/or the second space. For example, when the processor (e.g., the processor  120  of  FIG.  1   ) of the electronic device  200  detects an event for changing the open/closed state of the electronic device  200 , the processor may be set to control an operation of the first housing  210  through an actuator  260 . In an embodiment, the first housing  210  may be manually protruded from the second housing  220  through a user&#39;s operation. 
     The processor (e.g., the processor  120  of  FIG.  1   ) of the electronic device  200  may display an object in various ways in response to a display area corresponding to a certain amount of protrusion of the first housing  210  and may control to execute an application program. 
     According to an embodiment, the electronic device  200  may include at least one of an input device  203 , a sound output device  207 , a sensor module  204 , a camera module  205 , a key input device (not shown), and an indicator (not shown). 
     According to an embodiment, the input device  203  may be referred to as a microphone. The input device  203  may include a plurality of microphones disposed to detect the direction of sound. The sound output device  207  may be a speaker. 
     According to an embodiment, the sensor module  204  may generate an electrical signal or data value corresponding to an internal operating state of the electronic device  200  or an external environmental state. 
     According to an embodiment, the camera module  205  may be disposed on the front surface of the second housing  220  of the electronic device  200 . A camera device may include a camera module including a plurality of cameras disposed on the rear surface of the electronic device  200 . According to an embodiment, the camera devices may include one or a plurality of lenses, an image sensor, and/or an image signal processor. According to an embodiment, the camera module  205  may be disposed under the flexible display  230  and may be configured to photograph a subject through a portion of an activation area of the flexible display  230 . 
     According to an embodiment, the electronic device  200  may include at least one antenna (not shown). 
       FIG.  3    is a diagram illustrating an internal structure in which a display of an electronic device is removed, according to an embodiment.  FIG.  4    is an enlarged view of area A of  FIG.  3    of an electronic device according to an embodiment. 
     Referring to  FIG.  3   , an electronic device  200  may include a first housing  210 , a second housing  220 , a display  230 , and a power transmission device  300 . 
     According to an embodiment, the first housing  210  may include a first surface  211  and a second surface  212  (e.g., the second surface  212  of  FIG.  2 A ) facing in a direction opposite to the first surface  211 . A second housing  220  may include a third surface  221  facing a same direction as the first surface  211  and a fourth surface  222  facing in a direction opposite to the third surface  221 . The second housing  220  may be slidably coupled to a portion of the first housing  210  in a first direction (+x-axis direction). 
     The second housing  220  may move in the first direction (+x-axis direction) or in the opposite direction (−x-axis direction) to the first direction with respect to the first housing  210  by the power transmission device  300 . The second housing  220  may be coupled to a portion of the power transmission device  300  disposed in the first housing  210 . The display  230  may be disposed on the first surface  211  of the first housing  210  and the third surface  221  of the second housing  220 . A portion of the display  230  may be fastened to the second housing  220 , and a remaining portion of the display  230  may be exposed to the outside according to the movement of the second housing  220 . The remaining portion of the display  230  may be wound and stored in the first housing  210 . For example, the exposed portion of the display  230  may face a second direction (+z-axis direction) perpendicular to the first direction (+x-axis direction). The first state, which is the open state, may be a state in which the second housing  220  is no longer moved away from the first housing  210 . For example, the first state may be a state in which a periphery far from the power transmission device  300  among the peripheries of the second housing  220  is no longer distant from the power transmission device  300 . The first state may be a state in which most of the display area of the display  230  faces the second direction (+z axis direction). The first state is a state in which the second housing  220  may move only in the first direction (+x-axis direction) so that the display  230  may be reduced. The second state, which is a closed state, may be a state in which the second housing  220  moves toward the first housing  210  and may not move any more in the first direction (+x-axis direction). For example, the second state may be a state in which a periphery far from the power transmission device  300  among the peripheries of the first housing  220  is no longer close to the power transmission device  300 . The second state may be a state in which the second housing  220  is movable in a direction opposite to the first direction (−x-axis direction), so that the display  230  may be enlarged. The third state may be a state in which the second housing  220  may move in both the first direction (+x-axis direction) or the opposite direction (−x-axis direction) to the first direction with respect to the first housing  210 . The third state may be a state in which the display  230  may be enlarged and reduced. 
     Referring to  FIG.  4   , a plate forming the third surface  221  of the second housing  220  may be coupled to a rack gear  330  having a length and extending in the first direction (+x-axis direction). The rack gear  330  may engage with the pinion gear  320  and move in the first direction (+x-axis direction) or in the opposite direction (−x-axis direction) to the first direction according to the rotation of the pinion gear  320 . By the movement of the pinion gear  320 , the second housing  220  may move in the first direction (+x-axis direction) to reduce the display  230 , or may move in the direction opposite to the first direction (−x-axis direction) to enlarge the display  230 . 
     According to an embodiment, the pinion gear  320  may be engaged with the rack gear  330 . For example, a portion of the gears of the pinion gear  320  may be engaged with a portion of the gears of the rack gear  330 . In the state of looking at the pinion gear  320  in the first direction (+x-axis direction) and a direction (+z-axis direction) perpendicular to the second direction (+y-axis direction), the rack gear  330  may move in the first direction (+x-axis direction) when the pinion gear  320  rotates counterclockwise, and move in a direction opposite to the first direction (−x-axis direction) when the pinion gear  320  rotates clockwise. 
     The actuator  310  may rotate the pinion gear  320  through a shaft coupled to the pinion gear  320 . The actuator  310  may be supported by the first housing  210 , and may convert an electrical energy into kinetic energy to transmit rotational force to the pinion gear  320 . The actuator  310  may be referred to as a motor. For example, the actuator  310  may be a step-motor. 
     In order to generate sufficient power while reducing the size of components according to the limited mounting space in the electronic device, the actuator  310  may be a step motor. The actuator  310 , which is a step motor, may provide rotation of a designated angle to the pinion gear  320 . The actuator  310  may rotate the pinion gear  320  coupled to the shaft of the actuator  310  and move the rack gear  330  according to the rotation of the pinion gear  320 . The actuator  310  may enlarge or reduce the display  230  to a designated length. 
     The hall sensor  350  may be disposed to be spaced apart from the pinion gear  320  in the second direction (+z-axis direction). The hall sensor  350  may detect the direction and magnitude of the magnetic force around the hall sensor  350 . For example, the hall sensor  350  may detect the magnetic force transmitted through the pinion gear  320 . The pinion gear  320  may transmit the magnetic force generated by magnets disposed around the axis of the actuator  310  to the hall sensor  350 . The magnets may be disposed in the motor housing  340  and disposed around the axis of the actuator  310 . 
     The hall sensor  350  may obtain data related to an intensity and direction of the magnetic force transmitted through the pinion gear  320 , and the processor (e.g., the processor  120  of  FIG.  1   ) may identify a rotation angle of the pinion gear based on data related to the change in the magnetic force. For example, the processor  120  may obtain data related to the intensity and direction of the magnetic force transmitted through the pinion gear  320  through the hall sensor  350 . As the pinion gear  320  is rotated by the actuator  310 , a distance between the gear of the pinion gear  320  and the hall sensor  350  may be changed. By changing the distance between the pinion gear  320  and the Hall sensor  350 , the intensity and direction of the magnetic force transmitted to the Hall sensor  350  may be changed. By changing the intensity and direction of the magnetic force transmitted to the hall sensor  350 , the processor  120  may obtain the rotation direction and rotation angle of the actuator  310 . 
     According to the above-described embodiment, the electronic device  200  may identify a movement distance of the second housing  220  by identifying the rotation direction and the rotation angle of the actuator  310 , and identify an area in which the display  230  is exposed in the second direction (+z-axis direction). The electronic device  200  may determine an activation area of the display  230  or set a user environment of the display  230  based on the exposed area of the identified display  230 . 
     According to the above-described embodiment, even when the hall sensor  350  and the magnet are disposed at designated positions, the electronic device  200  may identify the rotation angle and the rotation direction of the actuator  310 , thereby enabling a stable operation. For example, although accurate position measurement may be difficult due to interference by surrounding signals when the hall sensor  350  or the magnet moves, the electronic device  200  according to an embodiment may identify a rotation angle and a rotation direction of the actuator  310  without moving the hall sensor  350  or the magnet. 
     According to an embodiment, as selecting the step motor as the drive, the electronic device  200  may secure a mounting space inside the electronic device  200  and omit an encoder for identifying a rotation angle of the motor, thereby reducing the overall size of the power transmission device  300 . 
       FIG.  5 A  is a perspective view illustrating an electronic device and a power transmission structure of the electronic device according to an embodiment, and  FIG.  5 B  is a perspective view illustrating a structure of a power transmission device according to an embodiment. 
     Referring to  FIGS.  5 A and  5 B , the power transmission device  300  may include a motor housing  340 , an actuator  310 , a shaft  311 , a pinion gear  320 , a magnet set  510 , a hall sensor  350 , and/or a metal plate  520 . 
     According to an embodiment, the motor housing  340  may include a first space  591  and a second space  592 . The motor housing  340  may accommodate a portion of the drive unit  310  that is a motor, the shaft  311  of the drive unit  310 , the pinion gear  320  connected to the shaft  311 , and the rack gear  330  engaged with the pinion gear  320 . The motor housing  340  may support the components that configure the power transmission device  300  and may couple the power transmission device  300  to the second housing  220  of the electronic device  200  (e.g., the electronic device  200  of  FIG.  2   ). 
     According to an embodiment, the actuator  310  may occupy the first space  591  of the motor housing  340 . The actuator  310  may be seated on the first space  591  of the motor housing  340  and fixed in the electronic device  200 . 
     According to an embodiment, a portion of the shaft  311 , a pinion gear  320  connected to the shaft  311 , and a portion of the rack gear  330  engaged with the pinion gear  320  may be disposed in the second space  592  of the motor housing  340 . The motor housing  340  may include a partition wall  593  separating the first space  591  and the second space  592 . The partition wall  593  may include a through hole through which the shaft  311  of the actuator  310  may pass. The partition wall  593  may rotatably support the shaft  311 . The shaft  311  may extend from the actuator  310 , pass through the first partition wall  593 , and extend into the second space  592 . The shaft  311  may receive a power from the actuator  310  and rotate. The second space  592  may be surrounded by the first partition wall  593  and the second partition wall  593 . The first partition wall  593  may distinguish between the first space  591  and the second space  592 , and the second partition wall  593  may form a portion of an outer surface of the motor housing  340 . The first partition wall  593  may face the second partition wall  594 . The shaft  311  may extend from the actuator  310  and pass through the first partition wall  593 . 
     A portion of the shaft  311  passing through the first partition wall  593  may be surrounded by a first bearing (not shown), and an end portion of the shaft  311  inserted into the second partition wall  594  may be surrounded by the second bearing  530 . The inner diameters of each of the first bearing and the second bearing  530  may correspond to the diameters of the shaft  311 . 
     According to an embodiment, the pinion gear  320  may be fastened to the shaft  311 . The shaft  311  may pass through the pinion gear  320 , and the rotation shaft of the shaft  311  and the driving shaft of the actuator  310  may pass through the center of the pinion gear  320 . As the pinion gear  320  is fixed to the shaft  311 , the pinion gear  320  may rotate by rotation of the shaft  311 . The pinion gear  320  may receive power transmitted from the actuator  310  through rotation of the shaft  311 . 
     The pinion gear  320  may be engaged with the rack gear  330 . The rack gear  330  may include gear teeth  331  corresponding to the gear teeth of the pinion gear  320  formed on one surface thereof. According to the rotation of the pinion gear  320 , the rack gear  330  may move in a direction perpendicular to the rotation axis of the pinion gear  320 . By the pinion gear  320  and the rack gear  330 , the power transmission device  300  may convert the rotational motion into a linear motion. 
     According to an embodiment, the magnet set  510  may be disposed to surround a portion of the shaft  311 . The magnet set  510  may be disposed to be spaced apart from the pinion gear  320  in the rotational axis direction. For example, the magnet set  510  may be spaced apart from the outer circumferential surface of the shaft  311  and may surround the shaft  311 . The magnet set  510  may be spaced apart from the pinion gear  320  and disposed to contact the motor housing  340 . For example, the pinion gear  320  may be disposed in the second space  592  formed by the first partition wall  593  and the second partition wall  594  of the motor housing  340 . The pinion gear  320  may be spaced apart from each of the first partition wall  593  and the second partition wall  594  and may be positioned in the second space  592 . The magnet set  510  may be attached to the motor housing  340  and supported by the motor housing  340 . A plurality of magnets  511  may be attached to the motor housing  340  using an adhesive or an adhesive tape. The magnet set  510  may be attached to the first partition wall  593  or the second partition wall  594  of the motor housing  340 . Since a plurality of magnets  511  and  512  are coupled within the motor housing  340 , the plurality of magnets  511  and  512  may be fixed even when the actuator  310  rotates. 
     According to an embodiment, the magnet set  510  may include a plurality of magnets  511  and  512 . The plurality of magnets  511  and  512  may be symmetrical with respect to a rotation axis of the shaft  311 . For example, the first magnet  511  and the second magnet  512  may be spaced apart from the shaft  311  by substantially the same distance. The magnet set  510  may include the plurality of magnets  511  and  512 , but is not limited thereto. For example, the magnet set  510  may be formed in a doughnut shape to surround the shaft  311 . 
     According to an embodiment, the rack gear  330  may be inserted into a guide groove  342  of the motor housing  340  and disposed on one surface of the motor housing  340 . The motor housing  340  may include a guide groove  342  for guiding movement of the rack gear  330  and maintaining engagement with the pinion gear  320 . The guide groove  342  may be formed on an inner surface of the motor housing  340  forming the second space  592 . The motor housing  340  may include a support part  341  protruding from the guide groove  342  and supporting the guide groove  342  in order to support the rack gear  330 . The guide groove  342  may be formed in the first partition wall  593  and the second partition wall  594  forming the second space  592 , and the support part  341  may be in contact with the guide groove  342  and may be formed at an end of the first partition wall  593  and/or the second partition wall  594 . 
     According to an embodiment, the rack gear  330  may include a recess  337  in which gear teeth  331  are disposed, and may include a guide rail  336  having a height toward the shaft  311  than the recess  337 . For example, a distance between the recess  337  and the shaft  311  may be longer than a distance between the guide rail  336  and the shaft  311 . As the guide rail  336  is inserted into the guide groove  342 , the moving direction of the rack gear  330  may be guided, and the rack gear  330  may be supported by the guide groove  342 . 
     According to an embodiment, the hall sensor  350  may be disposed to face the pinion gear  320 . The hall sensor  350  may be spaced apart from the pinion gear  320  in a direction perpendicular to the rotation axis direction of the shaft  311 . The hall sensor  350  may detect magnetic force transmitted from the magnet set  510  through the shaft  311  and the pinion gear  320 . The hall sensor  350  may be disposed on another surface facing one surface of the motor housing  340  on which the rack gear  330  is disposed. The hall sensor  350  may detect the magnitude and direction of the magnetic force. 
     According to an embodiment, the metal plate  520  may be disposed in an area (e.g., an area facing an area in which the rack gear  330  is located with respect to the shaft  311 ) of the motor housing  340  in which the hall sensor  350  is located. 
     The metal plate  520  may be configured such that the direction of a magnetic force line emitted from the pinion gear  320  passes through the hall sensor  350  and is formed along the shape of the metal plate  520 . The metal plate  520  may increase the accuracy of detecting a magnetic field change using the hall sensor  350  according to the rotation of the pinion gear  320  by increasing the intensity of the magnetic field passing through the hall sensor  350 . The metal plate  520  may include an SPCC steel plate which is a ferromagnetic material to induce magnetic force. The metal plate  520  may face the pinion gear  320 , and the hall sensor  350  may be disposed between the methane plate  520  and the pinion gear  320 . The metal plate ( 520 ) may increase the magnetic flux in the closed loop and the hall sensor ( 350 ) may detect a change in the magnitude of the magnetic field measured according to the rotation of the pinion gear 
     According to the above-described embodiment, the power transmission device  300  may identify the rotation angle of the pinion gear  320  using the hall sensor  350 . By identifying the rotation angle of the pinion gear  320  through the hall sensor  350 , the processor  120  (e.g., the processor  120  in  FIG.  1   ) operatively connected to the hall sensor  350  may obtain a movement distance of the rack gear  330  according to rotation of the pinion gear  320 . Since the hall sensor  350  and the magnet set  510  at a fixed position are used, the electronic device  101  (e.g., the electronic device  101  of  FIG.  1   ) including the power transmission device  300  may prevent and/or reduce failure or damage of the hall sensor  350 , and may improve the accuracy of the hall sensor  350  since a change in the magnetic field is detected at a fixed position. By improving the accuracy of the hall sensor  350 , the processor  120  may secure the rotation angle of the pinion gear  320  and the accuracy of the movement of the rack gear  330 . 
       FIG.  6    is a cross-sectional view of the power transmission device of  FIG.  5 A  taken along line B-B′ of  FIG.  5 A  according to an embodiment, and.  FIG.  7    is a diagram illustrating a magnetic force line formed in components of a power transmission device according to an embodiment. 
     Referring to  FIGS.  6  and  7   , in the second space  592 , the arrangement relationship of the components of the power transmission device  300  and the flow of the magnetic force line are shown. 
     According to an embodiment, a shaft  311 , a pinion gear  320 , and a magnet set  510  may be disposed in the second space  592  of a motor housing  340 . The shaft  311  and the pinion gear  320  may be formed of a ferromagnetic material. The bearings  531  and  532  disposed in the first partition wall  593  and the second partition wall  594  may be formed of a paramagnetic material. The bearings  531  and  532  may rotatably support the shaft  311 . The motor housing  340  may accommodate the actuator  310  to fix the inside of the electronic device (e.g., the electronic device  101  of  FIG.  1   ) and rotatably support the shaft  311 . For example, the shaft  311  in the second space  592  of the motor housing  340  may be rotated by the actuator  310 . Since the first partition wall  593  and the second partition wall  594  are rotatably disposed, friction force may be generated between the shaft  311  and the first partition wall  593 , and the second partition wall  594 . In order to prevent and/or reduce damage due to friction force between the shaft  311  and the first partition wall  593  and the second partition wall  594 , a first bearing  531  disposed in the first partition wall  593  and a second bearing  532  disposed in the second partition wall  594  may be included. The first bearing  531  may surround the through portion of the shaft  311  in the first partition wall  593 . The first bearing  531  and the second bearing  532  may be formed of a ball bearing, a rolling bearing, or the like. However, it is not limited thereto, and the first bearing  531  and the second bearing  532  may be a fluid bearing. According to an embodiment, the first bearing  531  and the second bearing  532  may be formed of a paramagnetic material. 
     According to an embodiment, a plurality of magnets  511  and  512  may be disposed to face each other. The plurality of magnets  511  and  512  are disposed to be in contact with the first partition wall  593  passing through the shaft  311 , it is not limited thereto, and the plurality of magnets  511  and  512  may be disposed to be in contact with the second partition  594  facing the first partition  593 . 
     The rack gear  330  and the hall sensor  350  may face each other around the pinion gear  320  or the shaft  311 . The rack gear  330  may be in contact with the pinion gear  320  and may fill an open surface of the motor housing  340 . The hall sensor  350  may be disposed on another surface facing one surface of the motor housing  340  on which the rack gear  330  is disposed. The hall sensor  350  may be disposed at one end of the printed circuit board  590 . The other end of the printed circuit board  590  may have a connector  571 . The printed circuit board  590  may extend from the motor housing  340  and extend along the surface of the actuator  310 , and may be bent in a stepped area formed between the surface of the actuator  310  and the motor housing  340 . For example, the printed circuit board  590  may be a flexible printed circuit board (FPCB) having flexibility. The printed circuit board  590  may be electrically connected to the hall sensor  350  on one surface thereof. The printed circuit board  590  may be disposed between the hall sensor  350  and the metal plate  520 . The metal plate  520  may face the hall sensor  350  and may be attached to another surface of the printed circuit board  590 . The hall sensor  350  may be mounted on one surface of the printed circuit board  590 . The printed circuit board  590  may extend the flexible printed circuit board to the outside of the motor housing  340  to be connected to a motor connector or a main printed circuit board of the electronic device (e.g., the electronic device  101  of  FIG.  1   ). 
     Referring to  FIG.  7   , a magnetic force line moving in the second space may form a closed curve. The first magnet  511  and the second magnet  512  may be disposed to face each other. A polarity of a surface of the second magnet  512  facing the first magnet  511  may be the same as a polarity of a surface of the first magnet  511  facing the second magnet  512 . For example, the polarities of the surfaces of the first magnet  511  and the second magnet  512  facing the shaft  311  may be the same. The facing surfaces of the first magnet  511  and the second magnet  512  may be the same as N pole or the same as S pole. The direction of the magnetic flux m 1  transmitted from the first magnet  511  to the shaft  311  may be a direction in which the first magnet  511  faces the shaft  311 . The direction of the magnetic flux m 2  transmitted from the second magnet  512  to the shaft  311  may be a direction in which the second magnet  512  faces the shaft  311 . Since the shaft  311  and the pinion gear  320  are formed of a ferromagnetic material, a magnetic field may be strongly formed. 
     The direction of the magnetic flux m 3  formed in the shaft  311  may be parallel to the rotation axis of the shaft  311 . The direction of the magnetic flux m 4  formed in the pinion gear  320  may be formed in a direction toward the metal plate  520 . The metal plate  520  may be formed of a ferromagnetic material, and thus a magnetic force line may be guided toward the metal plate  520 . The magnetic flux m 5  passing through the hole sensor  350  may be formed in a direction toward the metal plate  520  by the magnetic force induced by the metal plate  520 . Inside the metal plate  520 , a direction of the magnetic flux m 6  may face the magnet set  510 , which is an extending direction of the metal plate  520 . 
     According to an embodiment, the magnetic force line formed in the second space  592  of the motor housing  340  may form a closed curve formed along the magnet set  510 , the shaft  311 , the pinion gear  320 , and the metal plate  520 . The direction of the magnetic force in the second space  592  of the motor housing  340  may be formed in a clockwise direction. However, it is not limited thereto, and when the polarity of the arranged magnet set  510  is changed, the direction of the magnetic force may be formed in a counterclockwise direction. For example, when the polarities of the surfaces of the first magnet  511  and the second magnet  512  facing each other are N pole, the direction of the magnetic flux may be formed clockwise as shown in  FIG.  7   . For another example, when the polarities of the surfaces of the first magnet  511  and the second magnet  512  facing each other are S pole, the direction of operation may be formed in a counterclockwise direction. 
     According to the above-described embodiment, the magnitude and direction of the magnetic force formed in the second space  592  may be detected through the hall sensor  350 . The hall sensor  350  may identify the magnetic force that changes according to a change in distance between the rotating pinion gear  320  and the hall sensor  350 , and the processor (e.g., the processor  120  of  FIG.  1   ) may detect a rotation angle and a rotation direction of the pinion gear based on the changed magnetic force. 
     According to an embodiment, the metal plate  520  may induce the magnetic force formed in the shaft  311  and the pinion gear  320  to the metal plate  520 . For example, a magnitude of a magnetic field formed in a direction from the pinion gear  320  toward the metal plate  520  may be greater than a magnitude of a magnetic field formed in a direction from the pinion gear  320  toward a direction opposite to the metal plate  520 . By disposing the metal plate  520  in contact with the hole sensor  350 , the magnitude of the magnetic field formed around the hole sensor  350  may be large. Since the intensity of the magnetic force passing through the hole sensor  350  may be increased, the accuracy of detecting a change in the direction of the magnetic force and a change in the magnitude of the magnetic force may be increased through the hole sensor  350 . 
       FIGS.  8 A and  8 B  are diagrams illustrating a positional relationship between a gear tooth of a pinion gear of a power transmission device and a hall sensor according to an embodiment. 
     Referring to  FIGS.  8 A and  8 B , the power transmission device  300  may comprise a pinion gear  320  and a hall sensor  350 . The first magnet  511  and the second magnet  512  may be disposed above and below the shaft  311 . 
     According to an embodiment, magnetic force may be transmitted from the magnet set  510  to the hall sensor  350  via the shaft  311  and the pinion gear  320 . The hall sensor  350  may be disposed between the pinion gear  320  and the metal plate  520 . Depending on the distance between the hall sensor  350  and the pinion gear  320 , the magnitude of the magnetic force transmitted to the hall sensor  350  may be different. 
     According to an embodiment, the pinion gear  320  may include a gear tooth  321  and a gear root  322 . As the pinion gear  320  rotates, the tooth  321  and the gear root  322  may alternately face the hall sensor  350 . The distance d 1  between the gear tooth  321  and the hole sensor  350  when the gear tooth  321  of the pinion gear  320  faces the hall sensor  350  may be shorter than the distance d 2  between the surface of the gear root  322  and the hole sensor  350  when the gear root  322  of the pinion gear  320  faces the hall sensor  350 . 
     Since the distance d 1  is shorter than the distance d 2 , the magnitude of the magnetic force transmitted from the pinion gear  320  when the gear tooth  321  faces the metal plate  520  may be greater than the magnitude of the magnetic force transmitted from the pinion gear  320  when the gear root  322  of the pinion gear  320  faces the metal plate  520 . 
     According to an embodiment, since the gear tooth  321  and the gear roots  322  alternately face the hall sensor  350  or the metal plate  520  when the pinion gear  320  rotates, the intensity and direction of the magnetic force may change periodically. 
     According to the above-described embodiment, the power transmission device  300  or the electronic device including the power transmission device  300  may detect the rotation angle of the pinion gear  320  by detecting the change in magnetic force according to the rotation of the pinion gear  320 , and may identify the movement distance of the rack gear engaged with the pinion gear  320 . 
       FIGS.  9 A and  9 B  are diagrams illustrating examples of various arrangements of magnets in a power transmission device, according to an embodiment. 
     Referring to  FIG.  9 A , a power transmission device  300  may include a actuator  310 , a shaft  311 , and a plurality of magnet set  910 . The plurality of magnet set  910  may form a magnetic field connected to a hall sensor  350  (e.g., the hall sensor  350  of  FIG.  5 B ) through the shaft  311  and the pinion gear  320  (e.g., the pinion gear  320  of  FIG.  4   ) connected to the shaft  311 . 
     According to an embodiment, the magnet set  910  may include a plurality of magnets  911 ,  912 ,  913 , and  914 . The plurality of magnets  911 ,  912 ,  913 , and  914  may be symmetrically disposed around the shaft  311 . For example, the first magnet  911  may be disposed to face the second magnet  912 , and the third magnet  913  may be disposed to face the fourth magnet  914 . A distance between the first magnet  911  and the shaft  311  may be the same as a distance between the second magnet  912  and the shaft  311 . A distance between the third magnet  913  and the shaft  311  may be the same as a distance between the fourth magnet  914  and the shaft  311 . The first magnet  911  and the third magnet  913  may be point-symmetrical to the second magnet  912  and the fourth magnet  914  with respect to the center of the shaft  311 . In a state in which the magnets  911 ,  912 ,  913  and  914  are disposed to surround the shaft  311  of the actuator  310 , the magnetic flux transmitted to the shaft  311  as a whole may be maintained, since the total amount of magnetic flux induced from the magnets  911 ,  912 ,  913  and  914  may not change even when the vibration of the shaft  311  is generated by the operation of the actuator  310  and is biased to one side. 
     Referring to  FIG.  9 B , a power transmission device  300  may include an actuator  310 , a shaft  311 , and a magnet  920 . The magnet  920  may include a round magnet. The magnet  920  may form a magnetic field connected to a hall sensor  350  through the shaft  311  and the pinion gear  320  connected to the shaft  311 . The magnet  920  may surround a portion of the outer circumference surface of the shaft  311 . A distance between the outer circumference surface of the shaft  311  and the inner circumference surface of the magnet  920  may be constant. The magnetic flux transmitted to the shaft  311  may be maintained as a whole, since the total amount of magnetic flux induced from the magnet  920  may not change even when the shaft  311  is biased to one side. 
     According to the above-described embodiment, since the total amount of magnetic flux transmitted to the shaft  311  may be maintained, the power transmission device  300  may improve the accuracy of the amount of change in magnetic flux detected through the hall sensor  350  for detecting magnetic flux transmitted through the shaft  311  and the pinion gear  320 . By providing improved accuracy of the change in magnetic flux detected through the hall sensor  350 , the electronic device  101  including the power transmission device  300  may accurately detect an increased distance of the display according to the movement of the rack gear  330 . The electronic device  101  may control the activation area of the display according to the size of the display, and may adjust the size of the image displayed on the display. 
       FIG.  10 A  is a diagram illustrating a magnetic force distribution formed surround a power transmission device according to an embodiment and  FIG.  10 B  is a diagram illustrating a magnetic force distribution formed surround a power transmission device including a metal for magnetic induction, according to an embodiment. 
     Referring to  FIG.  10 A , the magnetic force passing from a magnet set  510  to a shaft  311 , a pinion gear  320 , and a hall sensor  350  may form a closed loop. The shaft  311  and the pinion gear  320  may be formed of a material having ferromagnetic material. Components disposed around the shaft  311  and the pinion gear  320  in the power transmission device  300  may be formed of a paramagnetic material. The magnetic force may tend to be strongly distributed in the ferromagnetic material. 
     According to an embodiment, the first magnet  511  may form a magnetic force toward the shaft  311  which is a ferromagnetic material and the second magnet  512  may form a magnetic force toward the shaft  311  which is a ferromagnetic material. A surface of the first magnet  511  facing the shaft  311  may have the same polarity as a surface of the second magnet  511  facing the shaft  311 . The polarity of the surface facing the shaft  311  of the first magnet  511  may be an N pole, and the polarity of the surface facing the shaft  311  of the second magnet  512  may be an N pole. The magnetic force of the first magnet  511  transmitted to the shaft  311  and the magnetic force of the second magnet  512  may have the same polarity and may spread to both sides at the point of meeting. The magnetic force transmitted to the pinion gear  320  along the shaft  311  may be formed in a direction of returning to the magnet set  510 . In a region away from the magnet set  510  along the shaft  311 , the influence of the magnetic field by the magnet set  510  may be further away. 
     Referring to  FIG.  10 B , since the hole sensor  350  is in contact with the metal plate  520 , the metal plate  520  may change a flow of a magnetic field formed in the power transmission device  300 . The metal plate  520  is a ferromagnetic body and may attract magnetic force transmitted to the outside of the shaft  311  and the pinion gear  320  to the metal plate  520 . For example, the metal plate  350  may concentrate the magnetic force transmitted from the pinion gear  320  and change the direction of the magnetic force to the direction of the length of the metal plate  350 . 
     According to an embodiment, the metal plate  350  may amplify the intensity of the magnetic field measured through the hall sensor  350  by enhancing the intensity of the magnetic force and amplify not only a component perpendicularly passing through the hall sensor  350  but also a magnetic force component in the parallel direction to the hall sensor  350 . Through the arrangement of the metal plate  520 , amount of change in magnetic force of two directions may largely occur, and the hall sensor  350  may obtain a rotation direction and a rotation degree of the pinion gear  320 . For example, the permeability of the magnetic force may be high, and the magnetic force may be induced to adjacent metals. Through the metal plate  520  formed close to the pinion gear  320 , the magnetic force may form a closed loop connecting the magnet set  510 , the shaft  311 , and the metal plate  520 . By the metal plate  520 , a larger magnetic force is formed around the hall sensor  350 , and thus the hall sensor  350  may increase accuracy of detecting the magnetic force. 
       FIG.  11 A  is a diagram illustrating an example relationship between a rotation angle of a pinion gear of a power transmission device and a hall sensor according to an embodiment  FIGS.  11 B and  11 C  are graphs illustrating a change in a magnetic field magnitude according to a position of a pinion gear of a power transmission device, according to an embodiment. 
     Referring to  FIG.  11 A , the pinion gear  320  may include a plurality of gear teeth  321   a  and  321   b . The plurality of gear tooth  321   a  and  321   b  may be 10, and the angle (Θ 1 ) between the gear teeth may be 36 degrees. 
     According to an embodiment, when the gear tooth of the plurality of gear teeth  321   a  and  321   b  of the pinion gear  320  approach the hole sensor  350 , the magnitude of the magnetic force S detected through the hole sensor  350  may increase. For example, when the first gear tooth  321   a  is disposed close to the hall sensor  350 , the magnetic force detected by the hole sensor  350  in the z-axis direction may be stronger than the magnetic force when a surface of a gear root between the first gear tooth  321   a  and the second gear tooth  321   b  faces the hole sensor  350 . 
     When the gear tooth of the plurality of gear teeth  321   a  and  321   b  of the pinion gear  320  approach the hole sensor  350 , the magnetic force in the x-axis direction may change. For example, when the first gear tooth  321   a  is disposed close to the hole sensor  350  and then moved away, the influence of the first gear tooth  321   a  is large, and thus the magnetic force in the x-axis direction may decrease. At a point where the influence of the second gear tooth  321   b  is greater than the influence of the first gear tooth  321   a , the magnetic force in the x-axis direction may increase. 
     According to an embodiment, when the surface of the gear root between the plurality of gear teeth  321   a  and  321   b  of the pinion gear  320  faces the hall sensor  350 , the magnetic force in the z-axis direction may be weak, and the magnetic force in the x-axis direction may change. For example, when the surface of the gear root moves away from the hole sensor  350 , the influence of the second gear tooth  321   b  increases, and thus the magnetic force in the x-axis direction may increase. 
     Referring to  FIG.  11 B , the magnitude of the magnetic field in the z-axis direction obtained through the hole sensor  350  may have an upper end value when it is 12 degrees, and then, may have an upper end value at a period of 36 degrees. The magnitude of the magnetic field in the z-axis direction obtained through the hall sensor  350  may have a lower end value when it is 30 degrees, and then, may have a lower end value at a period of 36 degrees. 
     The hall sensor  350  may detect rotation by 1/10 per period based on the upper end value. For example, the hall sensor  350  may detect rotation by 36 degrees per period based on the upper end value. 
     Referring to  FIG.  11 C , the electronic device  101  or the power transmission device  300  may identify a rotation direction of the pinion gear  320  based on the amount of change in the magnetic field in the z-axis direction and the amount of change in the magnetic field in the x-axis direction obtained through the hall sensor  350 . 
     When the pinion gear  320  rotates clockwise as shown in  FIG.  11 A , the magnetic field in the x-axis direction may be in a decreasing trend when the magnitude of the magnetic field in the z-axis direction obtained through the hall sensor  350  has an upper end value. When the pinion gear  9320  is rotated counterclockwise unlike  FIG.  11 A , the magnetic field in the x-axis direction may be increasing trend when the magnitude of the magnetic field in the z-axis direction obtained through the hall sensor  350  has an upper end value. 
     According to the above-described embodiment, the electronic device  101  may detect that the actuator  310  rotates in a forward direction or in a reverse direction by comparing the magnitude of the magnetic field in the x-axis direction and the magnitude of the magnetic field in the z-axis direction through the hall sensor  350 . According to an embodiment, the electronic device  101  may identify whether the display is being enlarged or the display is being reduced based on detecting the rotation direction of the actuator  310 . 
     According to an embodiment, the size of the activation area of the display may be identified based on the period of the upper end value of the magnetic field in the z-axis direction detected through the hall sensor  350 . 
     According to an example embodiment, an electronic device (e.g., the electronic device  200  of  FIG.  4   ) may comprise: a first housing(e.g., the first housing  210  of  FIG.  4   ), a second housing(e.g., the second housing  220  of  FIG.  4   ) slidably coupled to the first housing, a rollable display (e.g., the flexible display  230  of  FIG.  2 B ) configured to be enlarged or reduced based on a movement of the second housing, a rack gear (e.g., the rack gear  330  in  FIG.  4   ) disposed on the second housing, a pinion gear (e.g., pinion gear  320  in  FIG.  4   ) driven in engagement with the rack gear, an actuator (e.g., drive unit  310  in  FIG.  4   ) configured to rotate the pinion gear and coupled with the pinion gear by a shaft, a first magnet (e.g., first magnet  511  in  FIG.  5 B ) surrounding at least part of the shaft, and spaced apart from the pinion along to the shaft, and a hall sensor (e.g., hall sensor  350  in  FIG.  4   ) spaced apart from the pinion gear in a direction perpendicular to the shaft, and a processor (e.g., the processor  120  in  FIG.  1   ), wherein the processor is configured to obtain data related to a change in the magnetic force using the hall sensor and identify a rotating angle of the pinion gear based on the data related to a change in the magnetic force. 
     According to an example embodiment, the electronic device may further comprise a second magnet (e.g., the second magnet  512  of  FIG.  5 B ) facing the first magnet, with respect to the shaft, and the polarity of each of the first magnet and the second magnet facing the shaft may be the same. 
     According to an example embodiment, the magnet may include a through hole through which the shaft passes. 
     According to an example embodiment, the electronic device may further comprise: a printed circuit board (e.g., printed circuit board  590  in  FIG.  6   ) having a surface connected to the hall sensor and a metal plate (e.g., metal plate  520  in  FIG.  6   ) disposed on another surface of the printed circuit board. 
     According to an example embodiment, the pinion gear may overlap the metal plate, when looking at the metal plate from above. 
     According to an example embodiment, the pinion gear may be disposed between the first magnet and the actuator. 
     According to an example embodiment, the first magnet may be disposed between the pinion gear and the actuator. 
     According to an example embodiment, the pinion gear and the shaft may comprise a ferromagnetic material. 
     According to an example embodiment, the electronic device may further comprise: a motor housing (e.g., motor housing  340  in  FIG.  3   ) surrounding the actuator and surrounding a portion of the pinion gear, and comprising a paramagnetic material, wherein the magnet may be disposed within the motor housing. 
     According to an example embodiment, the motor housing may include a partition wall (e.g., the first partition wall  593  or the second partition wall  594  of  FIG.  5 B ) rotatably supporting the shaft and a bearing disposed between the partition wall and the shaft. 
     According to an example embodiment, the first magnet may be attached to a surface facing the pinion gear of the support on which the bearing is disposed. 
     According to an example embodiment, a magnetic force line generated by the first magnet may include a closed curve passing through the first magnet, the shaft, and the pinion gear. 
     According to an example embodiment, a magnitude and direction of a magnetic field detected by the hall sensor may change based on a distance between a tooth of the pinion gear and one surface of the hall sensor. 
     According to an example embodiment, the processor may be configured to identify a movement distance of the pinion gear, based on a change in a magnetic field passing through the hall sensor. 
     According to an example embodiment, the processor may be configured to identify a rotational direction of the pinion gear, based on a change in a magnetic field passing through the hall sensor and a change in a magnetic field in a fourth direction perpendicular to the hall sensor. 
     According to an example embodiment, a power transmission device(e.g., power transmission device  300  in  FIG.  5 A ) may comprise: a motor housing (e.g., motor housing  340  of  FIG.  5 B ) including a first space (e.g., the first space  591  of  FIG.  5 B ) and a second space (e.g., the second space  592  of  FIG.  5 B ) distinct from the first space, a motor (e.g., the drive unit  310  of  FIG.  5 A ) disposed within the first space in the motor housing, a shaft (e.g., the shaft  311  of  FIG.  5 B ) disposed within the second space, the shaft extending from the motor and configured to be rotated by the motor, a partition wall (e.g., the partition wall  593  of  FIG.  5 B ) separating the first space and the second space, a pinion gear (e.g., pinion gear  320  of  FIG.  5 B ) disposed within the second space, the pinion gear coupled to the shaft and including a plurality of teeth, a first magnet (e.g., a plurality of magnets  511  and  512  of  FIG.  5 B ) surrounding a portion of the shaft and spaced apart from the pinion gear along to the shaft; and a hall sensor (e.g., hall sensor  350  of  FIG.  5 B ) spaced apart from the pinion gear in a direction perpendicular to the rotating axis direction of the shaft, and configured to detect a magnetic force transmitted from the first magnet through the shaft and the pinion gear. 
     According to an example embodiment, the power transmission device may further comprise: a rack gear (e.g., the rack gear  330  of  FIG.  5 A ) including a plurality of teeth disposed on a plane having a length and engaging with the pinion gear. 
     According to an example embodiment, the power transmission device may further comprise a second magnet (e.g., the second magnet  512  of  FIG.  5 B ) facing the first magnet (e.g., the first magnet  511  of  FIG.  5 B ) with respect to the shaft, and wherein a polarity of surfaces of the first magnet and the second magnet facing each other may be the same. 
     According to an example embodiment, the first magnet may include a through hall through which the shaft passes. 
     According to an example embodiment, the power transmission device may further comprise: a printed circuit board (e.g., printed circuit board  590  in  FIG.  5 B ) having a surface connected to the hall sensor, and a metal plate (e.g., the metal plate  520  of  FIG.  5 B ) disposed on another surface of the printed circuit board. 
     According to an example embodiment, the pinion gear may overlap the metal plate, when viewed in a direction from the pinion gear toward the hall sensor. 
     According to an example embodiment, the pinion gear may be disposed between the first magnet and the motor. 
     The electronic device according to an embodiment may be one of various types of electronic devices. The electronic devices may include, for example, a portable communication device (e.g., a smartphone), a computer device, a portable multimedia device, a portable medical device, a camera, a wearable device, a home appliance, or the like. According to an embodiment of the disclosure, the electronic devices are not limited to those described above. 
     It should be appreciated that an embodiment of the disclosure and the terms used therein are not intended to limit the technological features set forth herein to particular embodiments and include various changes, equivalents, or replacements for a corresponding embodiment. With regard to the description of the drawings, similar reference numerals may be used to refer to similar or related elements. It is to be understood that a singular form of a noun corresponding to an item may include one or more of the things, unless the relevant context clearly indicates otherwise. As used herein, each of such phrases 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, or all possible combinations of the items enumerated together in a corresponding one of the phrases. As used herein, such terms as “1st” and “2nd,” or “first” and “second” may be used to simply distinguish a corresponding component from another, and does not limit the components in other aspect (e.g., importance or order). It is to be understood that if an element (e.g., a first element) is referred to, with or without the term “operatively” or “communicatively”, as “coupled with”, “coupled to”, “connected with”, or “connected to” another element (e.g., a second element), the element may be coupled with the other element directly (e.g., wiredly), wirelessly, or via a third element. 
     As used in connection with an embodiment of the disclosure, the term “module” may include a unit implemented in hardware, software, or firmware, or any combination thereof, and may be interchangeably used with other terms, for example, “logic,” “logic block,” “part,” or “circuitry”. A module may be a single integral component, or a minimum unit or part thereof, adapted to perform one or more functions. For example, according to an embodiment of the disclosure, the module may be implemented in a form of an application-specific integrated circuit (ASIC). 
     An embodiment as set forth herein may be implemented as software (e.g., the program  140 ) including one or more instructions that are stored in a storage medium (e.g., an internal memory  136  or an external memory  138 ) that is readable by a machine (e.g., the electronic device  101 ). For example, a processor (e.g., the processor  120 ) of the machine (e.g., the electronic device  101 ) may invoke at least one of the one or more instructions stored in the storage medium, and execute it, with or without using one or more other components under the control of the processor. This allows the machine to be operated to perform at least one function according to the at least one instruction invoked. The one or more instructions may include a code generated by a complier or a code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Wherein, the “non-transitory” storage medium is a tangible device, and may not include a signal (e.g., an electromagnetic wave), but this term does not differentiate between where data is semi-permanently stored in the storage medium and where the data is temporarily stored in the storage medium. 
     According to an embodiment of the disclosure, a method according to an embodiment of the disclosure may be included and provided in a computer program product. The computer program product may be traded as a product between a seller and a buyer. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., a compact disc read only memory (CD-ROM)), or be distributed (e.g., downloaded or uploaded) online via an application store (e.g., PlayStore™), or between two user devices (e.g., smart phones) directly. If distributed online, at least part of the computer program product may be temporarily generated or at least temporarily stored in the machine-readable storage medium, such as memory of the manufacturer&#39;s server, a server of the application store, or a relay server. 
     According to an embodiment of the disclosure, each component (e.g., a module or a program) of the above-described components may include a single entity or multiple entities, and some of the multiple entities may be separately disposed in different components. According to an embodiment of the disclosure, one or more of the above-described components may be omitted, or one or more other components may be added. Alternatively or additionally, a plurality of components (e.g., modules or programs) may be integrated into a single component. In such a case, according to an embodiment of the disclosure, the integrated component may still perform one or more functions of each of the plurality of components in the same or similar manner as they are performed by a corresponding one of the plurality of components before the integration. According to an embodiment of the disclosure, operations performed by the module, the program, or another component may be carried out sequentially, in parallel, repeatedly, or heuristically, or one or more of the operations may be executed in a different order or omitted, or one or more other operations may be added. 
     While the disclosure has been illustrated and described with reference to an embodiment, it will be understood that the embodiment are intended to be illustrative, not limiting. It will be further understood by those skilled in the art that various changes in form and detail may be made without departing from the true spirit and full scope of the disclosure, including the appended claims and their equivalents. It will also be understood that any of the embodiment(s) described herein may be used in conjunction with any other embodiment(s) described herein.